Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2020-2022
  • 1990-1994  (1,011)
  • 1985-1989  (861)
  • 1850-1859
  • 1991  (1,011)
  • 1988  (861)
  • Inorganic Chemistry  (1,412)
  • Atomic, Molecular and Optical Physics  (460)
Material
Years
  • 2020-2022
  • 1990-1994  (1,011)
  • 1985-1989  (861)
  • 1850-1859
Year
  • 101
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2091-2100 
    ISSN: 0009-2940
    Keywords: Perylene ; Terrylene ; Quaterrylene ; Oligorylenes ; Oligo(1,4-naphthylene)s ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A homologous series of oligo(1,4-naphthylene)s from the binaphthyl 6 to the sexinaphthylene derivative 10 were synthesized successively. The Pd(O)-catalyzed reaction between aryl bromides and arylboronic acids was used as a coupling method. By appropriate choice of the stoichiometry, the method allowed isolation of the intermediates 20 and 21. Under the influence of potassium in 1,2-dimethoxyethane the 1,4-bridged naphthylenes 6 - 10 were partially cyclized to perylene and terrylene units. This anionic cyclization displayed a high regioselectivity. Complete cyclization to the oligorylenes 3b, 4b and 5b was achieved under the influence of AlCl3 and CuCl2 on the bichromophoric systems 24, 25 and 28. The synthetic sequence allowed substitution by tert-butyl groups, so that the oligorylenes 2b, 3b, 4b and 5b were amenable to spectroscopic investigations. The trends in absorption maxima and fluorescence are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 102
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2141-2143 
    ISSN: 0009-2940
    Keywords: Sulfur-carbon compounds, bicyclic ; Titanocene chelate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfur Compounds, 143.  -  Synthesis and Characterisation of the New Bicyclic Sulfur-Carbon Compounds C6H8S8, C4H4S7, and C4H4S8The reaction of Cp4Ti2C2S4 (1) with two equivalents of the bissulfenyl chloride 1,2-C2H4(SCl)2 affords the new bicyclic compound C6H8S8 (2). Treatment of 1 with one equivalent of SxCl2 (x = 1, 2) results in Cp2TiC2S5 (3) and Cp2TiC2S6 (4), respectively, which on reaction with 1,2-C2H4(SCl)2 give the asymmetric bicyclic polysulfides C4H4S7 (5) and C4H4S8 (6), respectively.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 103
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2181-2184 
    ISSN: 0009-2940
    Keywords: Stannyl complexes ; Oxidative addition of Sn - C bonds ; Phosphinoalkylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition Metal Stannyl Complexes, 4.  -  Palladium and Platinum Complexes with Chelatting Phosphinoalkylstannyl Ligands by Oxidative Addition of Sn - C BondsReaction of (Ph3P)4Pd with two equivalents of Ph2PCH2CH2-SnR3 (R = Ph, Me) gives the Pd(II) stannyl complexes trans-Pd(PPh2CH2CH2SnR2)2 (2) by oxidative addition of two Sn - R groups and elimination of R - R. Products corresponding to earlier steps of the reaction are obtained by the reaction of (Ph3P)2Pt(C2H4) with Ph2P(CH2)nSnR3 (n = 2, 3). The phenylderivatives Ph2P[CH2]nSnPh3 afford the Pt(II) complexes (Ph3P)(Ph)PtPPh2[CH2]nSnPh2 (3), in which the two phosphorus atoms are cis-configurated, while Ph2PCH2CH2SnMe3 gives the Pt(IV) complex cis,cis,cis-(Me)2Pt(PPh2CH2CH2SnMe2)2 (3) as stable product.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 104
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2203-2207 
    ISSN: 0009-2940
    Keywords: Iron, mono-, bis-, and tris(tricarbonyl) complexes ; 9,10-Diboraanthracene, 9,10-dihydro-9,10-dimethyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mono-, Di-, and Tricomplexation of 9,10-Dihydro-9,10-dimethyl-9,10-diboraanthracene with Fe(CO)3 Complex FragmentsReaction of 9,10-dihydro-9,10-dimethyl-9,10-diboraanthracene (1c) with (CO)3Fe(C8H14)2 gives green (CO)3Fe(η6-1c) (2c), red [(CO)3Fe]2(η4,η6-1c) (3c), and orange [(CO)3Fe]3(η4,η4,η6-1c)(4c). The constitutions of 2c, 3c, 4c are derived from NMR and MS data and confirmed by X-ray structure analyses. In 2c the Fe(CO)3 group is η6-bonded to the heterocycle of planar 1c. 3c is formed from 2c by complexation of the diene of the benzo ring in anti position. In 4c both benzo rings of 2c are η4-bonded to the Fe(CO)3 groups anti to the η6-bonded Fe(CO)3 group.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 105
    ISSN: 0009-2940
    Keywords: 1-Alken-3-ynes ; Manganese(III) acetate ; Propargyl radical ; Ligand-transfer reaction ; Electron-transfer reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of the Propargylic Radical Stabilization by Carbon-Chain Length in Manganese(III)-Mediated Reactions of 1-Alken-3-ynes. - A Facile Synthetic Way to Long-Chain 4-Acetoxy-5-alkynoic AcidsBy investigation of reactions of 1-alken-3-ynes RC ≡ C - CH = CH2 4 with acetic acid/acetic anhydride, mediated by manganese(III) acetate, it has been found that the stabilization of propargylic radical adducts depends on the carbon-chain length of R in 4. R = C8H17 is shown to be the “critical” chain length when ligand transfer reaction appears to be the only way of stabilization of intermediates, thus providing a facile one-step access to long-chain 4-acetoxy-5-alkynoic acids. The dependence of the product ratios on the AcOH/Ac2O ratio has also been demonstrated.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 106
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2057-2063 
    ISSN: 0009-2940
    Keywords: Conformation analysis ; Lithium compounds ; Schiff bases ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ether-solvated lithium derivative of pinacolone anil (2a) is shown to be a centrosymmetric dimer (1) by X-ray diffraction analysis. Each lithium atom is bound to two nitrogen atoms, to the oxygen atom of diethyl ether, and weakly to two carbon atoms of a phenyl ring, but not to the vinyl moiety of the enamide anion. Despite conformational deconjugation, 1 is methylated at the carbon atom by methyl iodide. 1H-NMR shifts of 1 in solution are solvent-dependent. The results are discussed with respect to the “syn effect” in 1-azaallyl anions. The molecular structure of the dianil 3 of 2,2,7,7-tetramethyl-3,6-octanedione shows that a CH proton may approach the π face of an aromatic carbon atom down to a nonbonding distance of 274 A without causing much strain.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 107
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2075-2084 
    ISSN: 0009-2940
    Keywords: 1,3-Butadienes, polyalkyl ; Allenes ; Rearrangement ; propargylic, SN2′ ; 1,3-Dienes, orthogonal ; Organocuprates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically Hindered Double Bond Systems, 2.  -  On the Preparation of Highly Substituted 1,3-DienesHighly alkylated 1,3-dienes may be prepared by treatment of 2-butyne-1,4-diol derivatives with organocuprates in good yield. Thus, the 2,3-dialkylated butadienes 6a - d are obtained by treating the diacetate 4 with two equivalents of the cuprates prepared from the Grignard reagents 5a - d with CuBr/LiBr. Analogously, meso-14 is converted into a mixture of the di-tert-butyl-2,4-hexadienes (Z,E)- and (Z,Z)-15. The procedure may be extended to the synthesis of unsymmetrically substituted 1,3-dienes by either treating the appropriate diacetates with two equivalents of the same cuprate as examplified by the conversion of 18 into 19a and 19b or by employing a stepwise approach in which only one reactive acetate leaving group is available for the cuprate reagent at any given time, thus allowing the change of the organometallic reagent in the course of the synthesis (preparation of the dienes 26 from the monoacetates 22). The mechanisms of these reactions as well as those of several reactions leading to sideproducts are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 108
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2113-2118 
    ISSN: 0009-2940
    Keywords: Halo(trimethylsilyl)benzenes, carbodesilylation and elimination of ; Carbodesilylation ; Elimination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Halo(trimethylsilyl)benzenes with Electrophiles and Bases - Carbodestlylation and Elimination as Competitive ReactionsElimination to dehydrobenzenes takes place as competitive reaction in the base-catalyzed carbodesilylation of 1-halo-2-(trimethylsilyl)benzenes 1 with carbonyl compounds 2 in the presence of furans 3, 6. Elimination is preferred with increasing leaving tendency of the halides (I 〉 Br 〉 〉 Cl 〉 〉 F) and with decreasing reactivity of the carbonyl compounds. Exclusive elimination to 1,2-didehydrobenzenes - which are trapped with furans - occurs in the reaction when no electrophiles are present.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 109
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2119-2125 
    ISSN: 0009-2940
    Keywords: Didehydropyridines, synthesis of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Didehydropyridines from (Trimethylsilyl)pyridinesHalogen-substituted (trimethylsilyl)pyridines 2, 3, 5 - 7 and trifluoromethylsulfonyloxy-substituted (trimethylsilyl)pyridines 9b, 11b are obtained from 2- and 3-halopyridines 1, 4 or hydroxypyridines 8, 10, and 12. Reactions of the 3- and 2-(trimethylsilyl)pyridines 2,9b and 11b with bases in the presence of furans 15 give only protodesilylation or hydrolysis products but no indication is found for the formation of a 2,3-didehydropyridine. 3-Bromo-4-(trimethylsilyl)pyridine (5a) reacts with KOCMe3 in the presence of furan (15a) to give a mixture of products from which the isoquinoline derivative 20 and the tert-butoxypyridines 23, 24 are formed by addition to 3,4-didehydropyridine. Under comparable conditions far higher yields of 3,4-didehydropyridines are obtained by treatment of the 3-halo-2,4-bis(trimethylsilyl)pyridines 7 with strong bases.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 110
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2145-2146 
    ISSN: 0009-2940
    Keywords: Pyridinium salts ; Ring opening, nucleophilic ; Retro-ene reaction, intramolecular ; 1H-Imidazo[1,2-α]pyrimidines, 2,3-dihydro ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Chloro-4,5-dihydroimidazole (1) reacts with 4-(dimethylamino)pyridine to yield the stable pyridinium salt 2, which on treatment with some C  -  H acids produces 1,2,3,5-tetrahydroimidazo[1,2-α]pyrimidines 6.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 111
    ISSN: 0009-2940
    Keywords: Phosphametallacyclopropanes ; Isolobal building blocks ; Lewis basic behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXVII. - Synthesis, Structure and Reactivity of Phosphametallacyclopropanes with Isolobal ER (E = N,P,As,Sb) and Fe(CO)4 Building BlocksThe phosphidometallates \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} {[M] = (η5-C5H5)M-(CO)2}, resulting from the metal hydride complexes H[M]PPh2H [M = Cr (1), Mo (2), W (3)] by reduction with nBuLi, react with the geminal dihalides RECl2 to give the three-membered phosphametallacyclopropanes [ER = NC6F5 (M = Cr (1a), Mo (2a), W (3a)), PPh (M = Cr (1b), Mo (2b), W (3b)), PC6H11 (M = Cr (1c), Mo (2c), W (3c)), P-tBu (M = Cr (1d), Mo (2d), W (3d)), P(2,4,6-(tBu)3C6H2) (M = Cr (1e), Mo (2e), W (3e)), As(2,4,6-(tBu)3C6H2) (M = Cr (1f), Mo (2f), W (3f)), Sb-tBu (M = Cr (1g), Mo (2g))]. Reaction of Br2Fe(CO)4 with the corresponding dilithium compounds \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} affords the phosphido-bridged heterodimetallic complexes . According to X-ray structural analyses in 2a and 2f the P - E bond distances are shortened while the Mo - E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give P-tBu (4d), Sb-tBu (4g)]. By this reaction the antimony-containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by X-ray structural analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 112
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2191-2195 
    ISSN: 0009-2940
    Keywords: Heterodimetallic complexes ; phosphido-bridged ; Molybdenum complexes ; Rhenium complexes ; Proton exchange, isolobal ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton Exchange in Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 Against Cationic IB Metal Phosphane SpeciesDecacarbonyldirheniumreacts with hexacarbonylbis(η-cyclopentadienyl)dimolybdenum and diphenylphosphane to give Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 (1) with a Mo  -  Re bond as ascertained by an X-ray structure analysis. The bridging H atom of the heteronuclear metal-metal bond in 1 is deprotaned with DBU. The redox condensation reaction of the obtained anion1 and triphenylphosphane IB metal cations gave Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 [M = Au (2), Ag (3), and Cu (4)] containing an MReMo triangle. Their yields increase in the sequence of compounds 4 〈 3 〈 2. 1, 1-, and 2 were characterized by cyclovoltammetric measurements, NMR, IR, and UV/Vis spectra.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 113
    ISSN: 0009-2940
    Keywords: A-Frame complexes ; SO2-bridged complexes ; S, SO, and SO2 ligands ; Insertion reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Sulfur-, Sulfur Monoxide-, and Sulfur Dioxide-Bridged Dimetallic Complexes of the Type [M(CO)(dppm)]2(μ-S)(μ-L) and [(CO)3M'(dppm)2MX](μ-L') (M = Rh, Ir; M' = Mo, W, Mn; L = SO, SO2; L' = S, SO2; X = Cl, CO)The homo- and heterodimetallic complexes [M(CO)(dppm)]2-(μ-S)(μ-SO2) (M = Rh, Ir) (2a, b), [(CO)3M'(dppm)2MCl](μ-SO2) (M' = Mo, W; M = Rh, Ir) (4a - c), and [(CO)3Mn(dppm)2- Rh(CO)] (6) by passing sulfur dioxide through their solutions. The X-ray structure analysis of 5a shows the SO2 ligand in a bridging position, whereas one CO ligand is semibridging. Treatment of the same starting materials with thiirane S-oxide does not lead to the corresponding SO-bridged dimers, with the only exception of 1b, which yields the new SO complex [(Ir(CO)(dppm)]2(μ-S)(μ-SO) (3b). Passing H2S through a solution of 6, the sulfur-bridged complex [(CO)3Mn(dppm)2- Rh(CO)](μ-S) (8) is formed, accompanied by H2 elimination.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 114
    ISSN: 0009-2940
    Keywords: Trinuclear carbonyl complexes ; Molybdenum complexes ; Manganese complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; σ,α-Hydrocarbon bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-bridged Metal Complexes, XXI. - Addition of Tetracarbonylosmate and -ruthenate to Coordinated Unsaturated Hydrocarbons: Trinuclear Complexes with two σ,α-Allyl, Methylallyl, Cyclohexadiene, Cycloheptadiene, Cyclohexadienyl, Cycloheptatrien, and “Thiophene” Bridges The addition of organometallic nucleophiles [M(CO)4]2- (M = Os, Ru) to [(Cp)(ON)(OC)Mo(allyl)]+, [Cp(OC)2Mo(butadiene)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Mn(benzene)]+, [(OC)3Mn(thiophene)]+, [(OC)3-Mo(cycloheptatrienyl)]+ leads to the heterotrimetallic η1:η2-, η1:η3-, η1:η4-, η1:η5-, η1:η6-hydrocarbon-bridged complexes 1 - 7. The structures of cis-(OC)4Os[(μ-η1:η4-C7H9)Fe(CO)3]2 (4), cis-(OC)4Os[(μ-η1:5-C6H6-Mn(CO)3]2 (6), and cis-(OC)4Os-[μ-η1:η6-C7H7-Mo(CO)3]2 (7b) have been determined by X-ray analysis. The fluxional behaviour of 6 in solution has been studied in a temperature range from - 70 to +60°C. The comparison of observed and calculated 1H-NMR data indicates a 1,2-shift mechanism (ΔG+ = 49 kJ/mol).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 115
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2279-2287 
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines, lithiated ; Deprotonation ; Alkylation ; Deuteration ; Regioselectivity ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5,6-Dihydro-5-methylene-4H-1,2-oxazine 1 is smoothly converted by n-butyllithium into 1-Li which reacts with electrophiles such as D2O, carbonyl compounds, dimethyl sulfide, or an azo diester to give the γ-adducts 4a-4f. On the other hand, alkylation of 1-Li occurs exclusively at C-4 of the heterocycle and provides the α-adducts 3g and 3h. These reactions require the activation of 1-Li by tetramethylethylenediamine. Treatment with allyl bromide and methyl acrylate affords mixtures of regioisomers 3 and 4. 1,2-Oxazine 5 with a conjugated C = C bond is less acidic than 1 but is also converted into 1-Li, whilst compound 6, lacking the 6-methoxy group, is not deprotonated under standard conditions. The dianion of 1,2-oxazine 7 is generated by employing an excess of n-butyllithium. This dianion displays a similar regiochemical behavior as 1-Li. Deuterium is exclusively incorporated into the γ-position to give product 8, while methylation occurs at C-4 to produce 9. 1,2-Oxazine 3g with an additional 4-methyl group can also be metalated and affords γ-adducts 10 and 11 upon reaction with D2O or acetone. Treatment with methyl iodide gives a 3:1 mixture of regioisomers 12 and 13. Deuteration of 1,2-oxazines 14 and 16 bearing a 3-CF3 or 3-CO2Et substituent requires more severe deprotonation conditions to provide the γ-adducts 15 and 17 in moderate yields. MNDO calculations of neutral 1,2-oxazines, the corresponding carbanions, and the lithium compounds allow an insight into the structure and charge distribution of these species, and also an estimation of the relative acidities. The regioselectivity of reactions of 1-Li is discussed on the basis of these semiempirical calculations and comparison with related ambident nucleophiles.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 116
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2307-2313 
    ISSN: 0009-2940
    Keywords: Cycloadditions ; Cyclobutenes ; Cyclopropanes ; Tetracyclooctanes ; Photoreactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoreaction of 3,6-Dihydrophthalic Anhydride with AlkynesThe title compound 1 and various alkynes undergo photocycloadditions to give cyclobutenes 3 and/or tetracyclooctane derivatives 4. The proportion varies from 100% cyclobutene (3d) to 100% tetracyclooctane (4e, 1) according to the substituents on the alkyne and the temperature.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 117
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2335-2342 
    ISSN: 0009-2940
    Keywords: Cyclopentenes, 4-methylene-, synthesis of ; Cyclohexenones, 5-methylene-, synthesis of ; Tri(methylene)-methane chromium complexes ; [3 + 2]Cycloadditions with tri(methylene)methane complexes ; Carbene chromium complexes for organic synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 53.  -  4-Methylenecyclopentenes and 5-Methylenecyclohexenones from “Fischer Carbene” Chromium Complexes, Allenes, and AlkynesA method is described for the two-step construction of 4-methylenecyclopentenes 6 and 5-methylenecyclohexenones 7 from Fischer carbene chromium complexes, allenes, and alkynes. In the first step a tri(methylene)methane complex 3 is generated by the addition of the carbene chromium complex (CO)5Cr = C(0Et)Ph (1) to the allene 2. The second step involves an addition of 3 to alkynes HC≡CR [5: R = Ph (a), SiMe3 (b)] at 75°C to give 6 and/or 7 in high chemical yields. The product ratios strongly depend on the substituents R.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 118
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2378-2378 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 119
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2381-2389 
    ISSN: 0009-2940
    Keywords: Platinum complexes ; 1,2-Ethanediamines, 1,2-diaryl- ; Antitumor activity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various erythro- and threo-configurated dichloro[1-(hydroxyphenyl)-2-phenyl-1,2-ethanediamine]platinum(II) complexes were synthesized with the hydroxy group located in either the 2-, 3-, or 4-position of the phenyl ring (38-40). The diastereoisomeric 1-(3-hydroxyphenyl)-2-phenyl-1,2-ethanediamines (31, 32) and threo-1-(2-hydroxyphenyl)-2-phenyl-1,2-ethanediamine (30) were obtained by reduction of the 1,2-diazidoethanes and subsequent ether cleavage. The configuration of the threo-1,2-diazido-1-(2-methoxyphenyl)-2-phenylethane (5) was elucidated by X-ray analysis. The reduction of the erythro-1,2-diaryl-1,2-diazidoethanes, substituted with a methoxy group in ortho or para position, results in elimination reactions with formation of side products. The desired 1,2-diaryl-1,2-ethanediamines were finally synthesized via either an aziridine derivative 21 or by reduction of the respective dioximes 27, 28. The diamine ligands were converted into the corresponding dichloroplatinum(II) complexes 38 - 40.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 120
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2417-2422 
    ISSN: 0009-2940
    Keywords: Organosodium compounds ; Fluorenide carbanions ; Solvatation effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomeric, Tetrameric, and Polymeric Sodium Fluorenide · S [S = Me2N(CH2)2N(Me)(CH2)2NMe2, Me2N(CH2)nNMe2 (n = 2, 3)]The metallation of fluorene with sodium butanide (NanBu) in the presence of N bases yields solvated sodium fluorenide. Base adducts with bi- and tridentate N-chelating ligands have been isolated: Na(fluorenide)(pmdta) (1 [PMDTA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]n (2) [TMEDA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]4) (3) [TMPDA = Me2N(CH2)3NMe2]. According to X-ray diffraction studies monomeric (1), polymeric (2), and cyclic-tetrameric (3) structures are present in the crystal. These pronounced structural variations are explained on the basis of ionic contact aggregates where together with coulomb interactions the steric requirements of the ligands become rather important. Contact distances between Na ions and several C atoms of the carbanion may vary (ca. 260 - 300 pm) and definite coordination numbers become meaningless.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 121
    ISSN: 0009-2940
    Keywords: Aspartame ; L-Aspartyl-L-phenylalanine methyl ester ; Rhodium complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXIII1).  -  Aspartame as Tridendate Ligand in Organometallic Complexes: Preparation and Structure of Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me]Aspartame reacts with [Cp*RhCl2]2 in the presence of base to give the title complex 1 with the deprotonated tridendate dipeptide ester as ligand.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 122
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 75-81 
    ISSN: 0009-2940
    Keywords: Hexaphosphines, polycyclic ; Bicyclo[3.1.0]hexaphosphine ; Tricyclo[3.1.0.02.6]hexaphosphine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of the Polycyclohexaphosphines P6(C5Me5)4 and P6(C5Me5)2The cyclotriphosphine (PC5Me5)3 (1) decomposes in boiling benzene to give the bicyclo[3.1.0]hexaphosphine P6(C5Me5)4 (2) which yields the tricyclo[3.1.0.02.6] hexaphosphine P6(C5Me5)2 (3) in boiling xylene. The structures of 2 and 3 have been determined by 31P-, 13C-, and 1H-NMR spectroscopy and by X-ray crystallography. 3 represents the first member of a new class of polyphosphines. The specific thermolysis of 1 and 2 under comparatively mild conditions is based on the easy homolytic cleavage of P  -  C5Me5 bonds in these compounds.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 123
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 93-95 
    ISSN: 0009-2940
    Keywords: Phosphasilaethenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Knowledge of the “Silanephosphimine” (Phosphasilaethene) tBu2Si = PSitBu31,2)The lithium phosphide 3 acts as a source for the “silanephosphimine” 2. Thermolysis of 3 at 80-120°C in the presence of Li⊕ (tBu3Si⊖PH), CH2 = CMe2, or CH2 = CHCH = CH2 leads to products 4, 7 or 8, whose formation is interpretable by the reaction of the reactants with intermediately formed 2.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 124
    ISSN: 0009-2940
    Keywords: Diazaferrocene derivative ; Iron complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocycles as Ligands, X1).  -  2,2′,5,5′-Tetra-tert-butyl-1,1′-diazaferrocene - Stabilization of the Diheterometallocene Structure by Steric ShieldingStable 2,2′,5,5′-tetra-tert-butyl-1,1′-diazaferrocene (3) is obtained by the reaction of the corresponding lithiopyrrole with FeCl2. The X-ray analysis reveals a distorted sandwich structure influenced by repulsive interactions presumably both between the nitrogen atoms and the bulky tert-butyl substituents.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 125
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 115-127 
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines ; Deprotonation, stereoselective ; Substitution with retention of configuration ; Ring opening, reductive ; Amino alcohols ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 6-(trimethylsilyl)methyl-substituted 1,2-oxazine 1 can smoothly be deprotonated with n-butyllithium at C-4 to give a lithiated species which reacts with a variety of electrophiles to provide the new 1,2-oxazines 5 - 16 in good yields. Besides the preparative aspect of these transformations, the high stereoselectivity of many reactions is also interesting from a mechanistic point of view. By deprotonation of the 4-deuterated compound 5a it has been proven that n-butyllithium removes exclusively the proton (or deuteron) cis to the 6-CH2SiMe3 group. Also, in most cases the reaction of lithiated 1 with electrophiles occurs with overall retention of configuration to afford preferentially cis-1,2-oxazines (series a). A mechanistic proposal for this highly stereoselective deprotonation process, which seems to be governed by the 1,2-oxazine oxygen, is discussed including a comparison with a recently reported ab initio calculation dealing with oxime ethers. Similar deprotonation/substitution reactions are described for 1,2-oxazines 14, 2, 3, and 4. Possibly due to a differing carbanion structure a deviating behavior is observed in some cases. Several acidinduced and reductive ring-opening reactions of 1, 6a, 8a, and 14a demonstrate the potential of 4-substituted 1,2-oxazines for the stereoselective synthesis of polyfunctionalized compounds.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 126
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 129-139 
    ISSN: 0009-2940
    Keywords: Quinoxalinium salts ; Redox systems ; Electrochemistry ; Radical cations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical and Spectroscopic Characterization of N,N′-Dialkylquinoxalinium Redox SystemsThe outstanding position of the 1,4-isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations. Diquaternary salts [(R+)2(quin)](X-)2, R = Me, Et; quin = quinoxaline, 2,3- and 6,7-dimethyl- and 2,3,6,7-tetramethylquinoxaline, X- = BF4- or SbCl6- (4a - g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis. Cyclic voltammetry of the two-step redox systems of the Weitz type showed two reversible one-electron reductions with an extraordinarily stable radical cation intermediate (lg Kc 12). The redox potentials are less negative than those of the 4,4′-bipyridinium systems but also less positive in comparison to the values of N,N′-dialkylphenazinium compounds. The radical cation intermediates which include a TCNQ- salt cannot only be characterized by ESR, but also by absorption spectroscopy in comparison to the respective dications.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 127
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 163-173 
    ISSN: 0009-2940
    Keywords: Nitro compounds, aromatic ; Nitrite exchange by nucleophiles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleophilic Substitution of Nitrite in Nitrobenzenes, Nitrobiphenyls, and NitronaphthalenesAromatic compounds, accessible only by multistep procedures, can be synthesized easily by nucleophilic substitution of nitrite in nitrobenzenes, nitrobiphenyls, and nitronaphthalenes. Thus, meta-substituted phenols 3, 4, and 7 are obtained from 1,3-dinitrobenzene (1) and meta-substituted nitrobenzenes 6, as well as 3,5-disubstituted phenols 10 and 5-substituted resorcinol derivatives 11 from 3,5-disubstituted nitrobenzenes 9. The unsymmetrically substituted nitrobiphenyls 13, 15, 17, 19, 21, 23, 24, and 26 are also available by nitrite exchange from the corresponding easily accessible dinitrobiphenyls 16, 18, 20, 22, and 25. A nitrite exchange with nucleophiles is easily possible in the 1,5-disubstituted naphthalenes 29, 34, while in the case of the 1,8-disubstituted naphthalenes 31, 36 only the chloro derivative 36 undergoes this exchange under much stronger conditions in low yield.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 128
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 199-202 
    ISSN: 0009-2940
    Keywords: Borane adduct ; Organoboron compound, reducing agent ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organoboron Compounds, II1,2) - Preparation, Structure, and Reactions of Lithium [Cyano(triphenylphosphoranylidene)-methyl]trihydroborate(-1)(Cyanomethylene)triphenylphosphorane (5) adds borane (from 2) with formation of phosphorane-borane 6, which cannot be rearranged. 6 reacts with butyllithium to afford a crystalline lithium compound 9, which contains four tetrahydrofuran molecules. The X-ray structure analysis of 9 is reported, 9 is acting as a reducing agent towards halogeno and carbonyl compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 129
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3-dienes ; Insertion of alkynes and isocyanides into M = C bonds ; 2H-Pyrrole complexes of chromium and tungsten ; [1+2+2] Cycloaddition reactions of carbene complexes, alkynes and isocyanides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 501). - 2H-Pyrrole Complexes by a Stepwise Insertion of Alkynes and Isocyanides into M=C Bonds of Carbene Chromium or Tungsten Complexes2H-Pyrrole complexes 6a, b are obtained in two step by [1+2+2] cycloaddition reactions of the carbene complex (CO)5W=C(OEt)C6H5 (1d), the alkyne EtO-C≡CH (2) and isocyanides R1-NC 4a, b [R1 = CH3, c-C6H11). Ln=C(OEt)R 1 [LnM = Cr(CO)5, W(CO)5; R = C6H5, CH3] reacts with 2 to give 1-metalla-1,3-dienes 3a-d. (E)/(Z)-3d and 4 yield 6a, b via 1-aza-1,2,4-pentatriene complexes 5, which are open-chain precursors of 6. 2H-Pyrrole complexes 11 and 14 are synthesized in overall [2+1+2] cycloadditions withe reversed connectivity, or formation of 1-chroma-1,3-dienes 10 and 13 by condensation of the methylcarbene complex 1a with acid amides, and cyclisation again with isocyanides 4.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 130
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 247-248 
    ISSN: 0009-2940
    Keywords: 6-Hydrindanones ; Heart glycosides ; Bicyclo[4.3.0]nonanone ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3a-Hydroxy-6-hydrindanones of type 10 and 11 can be obtained by acid-catalyzed or Lewis acid-promoted cyclization reactions of ene-ketals of type 6 and 7. The compounds described are interesting building blocks for biologically active heart glycosides.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 131
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 259-264 
    ISSN: 0009-2940
    Keywords: Alkynylphosphines ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination Ability of Alkynylphosphines RnP(C≡C - R')3 - nAlkynylphosphines RP(C≡C-R')2 (2) react with one equivalent of octacarbonyldicobalt to yield selectively the η2-μ side-on-coordinated alkyne complexes (R)(R' - C≡C)P[(η2-C≡C-R')Co2(CO)6] (6); with another equivalent of Co2(CO)8 the dicoordinated compounds (R)P[(η2-C≡C-R')Co2(CO)6]2 (7) are obtained. 7 may also be synthesized directly by the reaction of 2 with two equivalents of Co2(CO)8. However, P(C≡C-Ph)3 yields with two equivalents of Co2(CO)8 the cyclic Co2P2C2 system {(Ph-C≡C)(R')P[(η2-C≡C-Ph)Co2(CO)5]} 2 (4) [R' = (η2-C≡C-Ph)Co2(CO)6]. Decarbonylation of 6a gives the six-membered cyclic compound {(Ph)(Ph - C ≡ C)P[(η2-C ≡ C - Ph)Co2(CO)5]}2 (8), while 6b yields the cluster Co3(CO)9(μ3-PtBu) (9). The structure of (tBu)P[(η2-C ≡ C - H)Co2)CO)6]2 (7b) is elucidated by an X-ray analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 132
    ISSN: 0009-2940
    Keywords: Digallium tetrabromide · 2 dioxane, reaction with alkyalithium compounds ; Lithium tetraalylgallantes ; Lithium-carbon-gallium bridge ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Ga2Br4 · 2 Dioxane with (Trimethylsilyl)methyllithium and Neopentyllithium  -  Synthesis and Molecular Structure of Lithium Tetraalkylgallanates(III) with Li-C-Ga BridgesGa2Br4 · 2 dioxane reacts with (trimethylsilyl)methyllithium or neopentyllithium to yield in n-pentane/diethyl ether solution besides elemental gallium exclusively the disproportionation product trialkylgallane. In pure n-pentane the dioxane adducts of the corresponding lithium tetraalkylgallantes (R = —CH2SiMe3 2; R = —CH2CMe3 4) are formed. 2 and 4 are also synthesized by the reaction of GaBr3 with alkyl lithium in the molar ratio 1:4. The crystal structure of 2 shows a dioxane-bridged dimer and Li-C-Ga bridges with lithium probably bound by the C-H s̰-bonds of the central carbon atoms.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 133
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 329-331 
    ISSN: 0009-2940
    Keywords: Imino phosphines ; Allyl anions ; Silyl migration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of an Imino(phosphoranylidenemethyl)phosphine: A New Hetero Allyl AnionReaction of the (dichlorophosphinyl)methylphosphonium salt 1 with three equivalents of sodium bis(trimethylsilyl)amide (2) in THF at - 78°C leads to the P-(phosphoranylidenemethyl)-substituted iminophosphine 4. Compound 4 is probably formed via 3 by 1,3-silyl migration. According to an X-ray analysis, 4 can be described as a hetero allyl anion with a 3- center-4-electron bond C1-P1-N1. Oxidative addition of sulfur or selenium results in formation of the imino(thioxo)phosphorane 8 or imino(selenoxo)phosphorane 9.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 134
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 365-369 
    ISSN: 0009-2940
    Keywords: Heterocyclodecadiynes, X-ray investigations of, PE spectra of ; Calculations, HF-SCF, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray investigations on the ten-membered heterocyclodiynes 1 - 4 reveal a chair-like conformation for all four compounds. The triple bonds are oriented parallel to each other, the distances between them varying between 3.10 Å (2) and 2.91 Å (1). All triple bonds are slightly bent, the deviation from 180° varies between 6 - 10°. The photoelectron spectra of 1 and 3 - 6 have been recorded. The first six bands have been assigned by comparing them with related species and MO calculations. In the case of 3 - 6, the HOMO is predicted to be a long pair combination. The splitting between the in-plane π-linear combinations η-i, η+i ranges from 0.9 eV (5) up to 1.5 eV (4).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 135
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 383-386 
    ISSN: 0009-2940
    Keywords: Diels-Alder reaction ; Cycloaddition ; Benzocycloheptenes ; Tetracyanoethylenes ; Triazolinediones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diels-Alder reactions of 5H-benzocycloheptene (1) with tetracyanoethylene (TCNE) afforded the [2+2] and [4+2] cycloadducts 7, 8, and 10 and the benzodicyanoheptafulvalene 9. The norcaradiene product 10 was synthesized independently by cycloaddition of TCNE to 7H-benzocycloheptene (3). The addition of 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) to 3 gave bis-urazole 13, which was formed by ene reaction followed by [4+2] cycloaddition. The spirocycloheptatriene 15 gave with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) the bisurazole 16.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 136
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 137
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 423-426 
    ISSN: 0009-2940
    Keywords: Bis(perfluoroisopropylseleno)mercury ; Silane, (perfluoroisopropylseleno)trimethyl ; Selenoketone, bis(trifluoromethyl) ; [4 + 2] Cycloadditions ; Retro Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Scavenging of Hexafluoroselenoacetone by Cycloadditions with Dienes and Preparation of Hg[SeCF(CF3)2]2 and (CH3)3SiSeCF(CF3)2Bis(perfluoroisopropylseleno)mercury (2) was obtained from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-diselenetane (1) and HgF2 in DMF, and (perfluoroisopropylseleno)trimethylsilane (3) from 2 and (CH3)3Sil. The reaction of 2 with (C2H5)2All as well as the pyrolysis of 1 yield a deep purple liquid in very small amounts, not sufficient for further characterisation, which is assumed to be hexafluoroselenoacetone (4). However, 4 is formed as an intermediate in the reaction of hexafluoropropene with CsF and selenium and can be trapped by isoprene or anthracene to form 5a, 5b, and 6, respectively. In boiling benzene a transformation of (CF3)2C=Se from 6 to 2,3-dimethyl-1,3-butadiene is accomplished yielding 7 in a retro Diels-Alder cleavage.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 138
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 475-480 
    ISSN: 0009-2940
    Keywords: 1,3-Azaphosphole, annulation to pyridine ; 2-Phosphaindolizines ; Pyridinium bromides, 1,2-dialkyl ; Phosphorus(III) chloride, condensation with CH2 groups ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 139
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 487-491 
    ISSN: 0009-2940
    Keywords: Bis[3-(2,3-dihydroxyphenoxy)propyl]amine hydrochloride ; 99mTc uptake ; Technetium, radiopharmaceutical containing ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Chelates of Medical Interest, III. - 99mTc Complexes with Tetradentate Dicatechol LigandsThe dicatechol ligand bis[3-(2,3-dihydroxyphenoxy)propyl]-amine hydrochloride, DIPACE (6), reduces the 99m[TcO4]- ion to lower valent 99mTc and subsequently forms a complex with the reduced 99mTc. The structure of benzylbis[3-(2,2-dimethyl-1,3-benzodioxol-4-yloxy)propyl]amine (4) is determined by X-ray crystallography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 140
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 509-513 
    ISSN: 0009-2940
    Keywords: 2-Aminoethyl phosphate complexes ; Magnesium complexes ; Calcium complexes ; Zinc complexes ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystalline magnesium, calcium, and zinc 2-aminoethyl phosphate complexes containing the monoanions PEAH⊖ have been prepared as the tetrahydrates (Ca, Zn) and the hexahydrate (Mg), and their structures determined by single-crystal X-ray methods. The structures of monoclinic Ca(PEAH)2·4 H2O and Zn(PEAH)2·4 H2O (space group C2/c) both contain polymeric chains with metal ions connected by bridging phosphate groups. The zinc atoms are in a tetrahedral environment of four oxygen atoms, while the calcium atoms are found to be hexacoordinated with two additional oxygen atoms from water molecules in axial positions. The triclinic Mg(PEAH)2·6 H2O (space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document}) contains discrete complex units with hexacoordinate magnesium atoms octahedrally surrounded by six oxygen atoms, four of which from water molecules in the equatorial plane and two from phosphate groups in axial positions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 141
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2785-2790 
    ISSN: 0009-2940
    Keywords: Enol ether ; Allylsilane ; Bromo ether ; 1,4-Diene ; Alkoxyalkylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The α,β-dibromo ethers 2, in situ generated from the vinyl ethers 1 and bromine, react with the allylsilanes 3 in the presence of ZnCl2 to give the β-bromo ethers 4. Treatment of 4 with Na in diethyl ether yields 1,4-dienes 5 in 62-79% overall yield.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 142
    ISSN: 0009-2940
    Keywords: Cycloadditions, dipolar ; Electron-transmission spectroscopy ; Norbornane systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of six 7-substituted norbornadienes with seven sulfonyl azides has been investigated. The products consist of either the novel azatetracyclic system 1 or the stereoisomeric bicycles 2 or of a mixture of them. The chemical behaviour of 1 has been studied. Mechanistically the results may be rationalized within the frame of the Mazzocchi-Houk model. The theoretical predictions of this model, concerning the π*and σ* energies, were confirmed experimentally by using electron-transmission spectroscopy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 143
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 957-965 
    ISSN: 0009-2940
    Keywords: Chromium complexes ; Carbene ligands ; alkenyl-substituted ; [2 + 1] Cycloaddition ; Vinylcyclopropane→cyclopentene rearrangement ; Cyclopropanes ; donor-acceptor-substituted ; Pyrrole derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Vinylcyclopropane and Cyclopentene Derivatives from Alkenyl-Substituted Chromium Carbene Complexes: Competition between Formal [2 + 1] and [3 + 2] Cycloadditions.The alkenyl-substituted chromium carbene complexes 1 - 4 were synthesized following the method of Aumann which starts from the corresponding aldehydes. At 80°C the styryl-substituted complex 1 and electron-deficient olefins smoothly provide vinylcyclopropane derivatives 6,8, 10, and 12 in good yields. On the other hand, methyl acrylate and the anisyl- and furyl-substituted vinylcarbene complexes 2 and 3 give mixtures of the expected vinylcyclopropanes and of cyclopentene derivatives. The pyrrolyl-substituted complex 4 and methyl acrylate exclusively afford the cyclopentenes 24a/b which are the result of a hitherto unprecedented formal [3 + 2] cycloaddition of the vinylcarbene complex to the olefin. However, there are strong arguments suggesting the corresponding vinylcyclopropanes as intermediates. The very smooth vinylcyclopropane→cyclopentene rearrangement probably occurs via zwitterionic intermediates that are wellstabilized by donor and acceptor substituents. Hydrolysis of 24a/b to the cyclopentanone derivatives 25a/b demonstrates that this new route to five-membered carbocycles should have synthetic potential.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 144
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1017-1023 
    ISSN: 0009-2940
    Keywords: Borates, triorgano-oxy, potassium salts ; N-Lewis base - diorgano(silyloxy)boranes ; Bicyclo[2.2.1]heptanes, heteroatom-containing, diastereomeric ; P-Lewis base - triorganoboranes, monocyclic, unsaturated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: OrganosubstitutedBicyclic and Monocyclic Compounds from 2,5-Dihydro-1,2,5-oxasilaboratolates1a)The potassium salts of the cyclic anions of (A: R, R′ = CH3; B: R = C2H5, R′ = CH3; C: R = C6H5, R′ = CH3 react with [(CH3)2NCH2]Br in THF to yield the bicyclic compounds 1a (X-ray crystal structure analysis), 1b/1b' (endo/exo-C2H5), and 1c/1c' (endo/exo-C6H5). D (R=CH3, R'=C6H5) reacts with [(CH)32NCH2]Br to form a 1:4 mixture of 1d together with the heterocycle (3d) with elimination of (CH3)2N-C3H7. - From A - D and CIP(C6H5)2 the six-membered heterocycles (2a-d) are obtained in yields of ca. 90%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 145
    ISSN: 0009-2940
    Keywords: Zirconium porphyrins ; Hafnium porphyrins ; Porphyrin double deckers ; Metal bisporphyrinates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of new zirconium and hafnium bisporphyrinate double deckers M(P)2 (M=Zr, Hf; P=OEP, TPP)2,3) is described. The complexes are characterized by UV/Vis/NIR and 1H-NMR spectroscopy and cyclic voltammetry. As compared with M=Ce, the redox potentials or the energies of the nearinfrared absorption bands of the corresponding radical cations [M(P)2]+ are lower by ≍ 0.2 V or higher by ≍ 2000 cm-1, respectively, Hence, there is a stronger π-π interaction between the porphyrin ligands as compared with the cerium analogues due to the smaller ionic radii of Zr(IV) and Hf(IV). X-ray crystallography of Zr(TPP)2 confirms the sandwich-like structure of the compound and the close proximity of the porphyrin ligands.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 146
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1083-1087 
    ISSN: 0009-2940
    Keywords: Calcium bis-L-pyroglutamate ; Lithium L-pyroglutamate ; Pyroglutamate coordination and conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calcium bis-L-pyroglutamate and lithium L-pyroglutamate are prepared by reaction of the metal hydroxides with L-pyroglutamic acid in aqueous solution. In the solid state calcium bis-L-pyroglutamate adopts a layer structure, built up by sixteen-membered rings consisting of four L-pyroglutamate ligands bridging four calcium centers by their carboxylate groups. All three oxygen donors of the L-pyroglutamate ligands are attached to metal centers. The calcium atom lies at the center of a slightly distorted octahedron formed by four carboxylate oxygens and two amide oxygen atoms. Lithium L-pyroglutamate also features a layer structure. All three oxygen donors of the L-pyroglutamate ligand have contacts with metal atoms. The coordination sphere of the lithium atom is a slightly distorted tetrahedron consisting of three carboxylate oxygen atoms and one amide oxygen atom. The investigation of aqueous solutions of the compounds by multinuclear NMR (1H, 13C, 17O) indicates extensive electrolytic dissociation in dilute solutions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 147
    ISSN: 0009-2940
    Keywords: Technetium complexes ; Isocarbonyl ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Carbonyl Syntheses, XX. - Simple Method for the Preparation of Tc(CO)3 Complexes: Synthesis, Structures, and Reactivity of the Novel Cubane-Type Cluster Na[Tc3(CO)9(OCH3)4]Carbonyltechnetium complexes of type LTc(CO)3 are accessible along a simple route from Na[Tc3(CO)9(OCH3)4] (2) which represents a novel alkoxy complex of cubane-type geometry (single-crystal X-ray diffraction study). 2 is an isolable product of the incomplete carbonylation of sodium pertechnetate (1) conducted in methanol. Under carbon monoxide pressure, 2 yields the binary metal carbonyl Tc2(CO)10 (3), pentamethyl-cyclopentadiene gives the halfsandwich complex (η5-C5Me5)Tc(CO)3 (4), and with benzene/hydrochloric acid the ionic complex [(η6-C6H6)Tc(CO)3]Cl (5) is formed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 148
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1131-1133 
    ISSN: 0009-2940
    Keywords: Alkanetellurenyl pseudohalides ; Alkanetellurenyl pseudochalcogenides ; Tellurenyl pseudohalides, pseudochalcogenides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Stable Alkanetellurenyl Pseudohalides and Pseudochalcogenides: (Me3Si)3CTeX (X=- CN, - SCN, - SeCN, - NCO, - N3) and (Me3Si)3CTe-Y - TeC(SiMe3)3 (Y=- NCN-, - NSN-)The first stable and isolable alkanetellurenyl pseudohalides and pseudochalcogenides, tris(trimethylsilyl)methanetellurenyl cyanide, thiocyanate, selenocyanate, isocyanate, azide (2-6) as well as bis[tris(trimethylsilyl)methyltelluro]carbodiimide and -sulfur diimide (7, 8) are obtained in high yields by the reaction of tris(trimethylsilyl)methanetellurenyl iodide (1) with the silver or potassium salts of the respective pseudohalides or pseudochalcogenides. 5-8 are also the first alkyltellurium(II) compounds with Te-N bonding. All compounds have been characterized by 1H-, 13C-, 125Te-NMR, mass, and IR spectroscopy.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 149
    ISSN: 0009-2940
    Keywords: Tetracyclo[6.2.1.02,6.05,10]undecaphosphane ; 3,4,7,9,11-pentaorganyl ; Undecaphospha-2,8-ethanonoradamantane ; Undecaphosphane(5) ; Phosphanes, polycyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Chemistry of Phosphorus, 211. - Pentaisopropyltetracycloundecaphosphane, P11iPr5 - Preparation and Structure Determination by Nuclear Magnetic ResonancePentaisopropyltetracycloundecaphosphane (1) has been obtained by reaction of iPrPCl2 with P4 and magnesium and subsequent thermolysis of the crude reaction product, and has been isolated in 91% purity. According to NMR-spectroscopic investigations, 1 has a constitution analogous to that of the hydrocarbon 2,8-ethanonoradamantane, thus being 3,4,7,9,11-pentaisopropyltetracyclo[6.2.1.02,6.05,10]undecaphosphane Compound 1 is formed as a mixture of two configurational isomers 1a and 1b, which differ from each other in their spatial arrangements of the isopropyl groups at P3 and P4.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 150
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1167-1169 
    ISSN: 0009-2940
    Keywords: Anion-cation interactions ; Carbonyl metalates ; Chromium complexes ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of KSi with M(CO)6 (M=Cr, Mo, W) and Cr(CO)5NMe3 - Crystal Structure of [K(DME)2]2[Cr2(CO)10] (DME=1.2-Dimethoxyethane)M(CO)6 (M=Cr, Mo, W) and Cr(CO)5NMe3 are reduced by KSi in DME during several days with formation of the anions [M2(CO)10]2⊖. These can be obtained from a DME/toluene solution as pale yellow or orange crystals of [K(DME)2]2[M2(CO)10] [M=Cr (1), Mo (2), W (3)]. A crystal structure determination of the chromium compound shows that strong interactions between the [Cr2(CO)10]2⊖ and the K⊕ ions exist in the solid state, leading to the formation of one-dimensional polymeric chains. 2 and 3 are isomorphous to 1 (powder diffraction, Rietveld method).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 151
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1191-1198 
    ISSN: 0009-2940
    Keywords: Bond cleavage ; C—C kinetics of ; Radicals, stability of ; Geminal substituents, energetic interaction of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of Substituents on the Strength of C-C Bonds, 10. - Resonance Stabilization of Alkyl Radicals by Two Geminal Cyano GroupsThe activation parameters of the homolytic cleavage of the Cq - Cq bonds of several dialkylated malonodinitriles (2-5) and of 1,1,2,2-tetracyanoethane (7) and the heat of dissociation of 6 in solution have been determined. Together with the ground state strain of the radical precursors (obtained from the heats of combustion or EFF calculations) the steric influence on the dissociation process has been determined. The resonance stabilization energy of α,α'-dicyanoalkyl radicals then calculated was (12.4 ± 0.9) kcal/mol. This result is discussed within the concept of capto-dative stabilization. The destabilizing interaction of two geminal cyano groups is apparently the same in the ground state of 2 - 7 and the radicals generated from them.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 152
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1203-1206 
    ISSN: 0009-2940
    Keywords: Dithienylethylene ; Cyclodimerization ; Photoinduced electron transfer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,1-Di-2-thienylethanol (1) undergoes light-induced (Δ 〉 400 nm) dehydration to afford 1,1-di-2-thienylethylene (2). Compound 2 is selectively converted into 1,6-cyclodimers under thermal or photochemical conditions. In these latter case the non-aromatic Diels-Alder adduct 3 can be characterized. An ET mechanism involving a methyldithienylcarbenium ion (9) as electron acceptor and a chain mechanism is proposed to account for the products.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 153
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2085-2090 
    ISSN: 0009-2940
    Keywords: 5H-Dibenz[c,e]azepines ; Imidates ; alkyl ; heterocyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocycles with an Azaallyl System, 4.  -  5H-Dibenz[c,e]azepines with Donor Groups at the 7-Position5H-Dibenz[c,e]azepines substituted with a methoxy (1) or methylthio group (10) at the 7-position have been synthesized from 6,7-dihydro-5H-dibenz[c,e]azepin-5-one (5) by regioselective O- or S-alkylation with methyl trifluoromethansulfonate and subsequent NH-deprotonation. According to the spectroscopic properties the semicyclic 7-membered alkyl imidates exist exclusively in the benzenoid 5H structure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 154
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2127-2139 
    ISSN: 0009-2940
    Keywords: Marine natural products ; Hemiketal formation, selective ; Denticulatins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total synthesis of the denticulatins 1 is described. Key feature is the efficient generation of the C-1-to-C-9 building block 37 by three consecutive stereoselective carbon - carbon bond-forming steps using chiral allylboronates. The C-10-to-C-17 building block was obtained by kinetic Sharpless resolution of an allylic alcohol followed by an Ireland-Claisen rearrangement.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 155
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 156
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2147-2147 
    ISSN: 0009-2940
    Keywords: Tricyclo[3.3.0.03,7]octanes ; Samarium iodide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,5-Dimethylbicyclo[3.3.0]octan-3,7-dione (2) was converted into 1,5-dihydroxy-3,7-dimethyltricyclo[3.3.0.03,7]octane (3) in the presence of Sml2 in 76% yield.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 157
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2161-2164 
    ISSN: 0009-2940
    Keywords: Gold(I) 2,4,6-tri(isopropyl)thiophenolate, hexamer ; Aurate(I), bis[2,4,6-tri(isopropyl)thiophenolato] ammonium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiolato Complexes of Monovalent Gold. Synthesis and Structure of [(2,4,6-iPr3C6H2S)Au]6 and (NH4)[(2,4,6-iPr3C6H2S)2Au]Reaction of Au(CO)Cl with 2,4,6-tri(isopropyl)thiophenol affords hexameric gold(I) thiolate [(2,4,6-iPr3C6H2S)Au]6 (1). According to an X-ray analysis 1 forms a centrosymmetrical twelve-membered Au - S ring in the chair conformation with the linearly coordinated Au atoms at the mid-edges and the S atoms at the corners of the heterocycle. When the reaction of 2,4,6-tri(isopropyl)thiophenol is carried out with AuI in liquid ammonia the thiolato complex [(2,4,6-iPr3C6H2S)2Au]- -NH+4 (2) is obtained. It crystallizes as NH4 · 2 · 3 NH3. The gold atom in 2 is linearly coordinated by two thiolato S atoms. The ammonium cation forms hydrogen bonds with three NH3 solvate molecules.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 158
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2165-2170 
    ISSN: 0009-2940
    Keywords: Titanocene complexes ; Zirconocene complexes ; Cyclopropene complexes ; Metallacyclobutenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metallacyclobutenes via η2-Cyclopropene Complexes of Titanocene and Zirconocene(η2-Cyclopropene)(trimethylposphane) complexes of titanocene (4, 5) and zirconocene (8) are obtained in good yields by the reaction of 1,2-diphenylcyclopropene (2) or 4,8-dioxaspiro[2.5]oct-1-ene (3) with bis(trimethylphosphane)titanocene (1) and (1-butene)(trimethylphosphane)zirconocene (7), respectively. In solution the new complexes 4 and 8 rearrange smoothly above room temperature to give the metallacyclobutene derivatives 6 and 9. All new compounds were characterized by spectroscopic methods (31P, 1H, 13C NMR), and the crystal structure of 9 was determined by an X-ray analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 159
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2185-2190 
    ISSN: 0009-2940
    Keywords: Cyclopentadienes, mono-, bis-, tris- ; DNMR ; Molybdenum, η5-complexes ; Tungsten, η5-complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation reactions of cyclopentadienyl-substituted chlorosilanes CpSiMe2Cl (Cp = C5H5, C5HMe4) with a number of phenols [C6H5OH, 1,3-C6H4(OH)2, 1,4-C6H4(OH)2, 1,3,5-C6H3(OH)3] in the presence of excess base led to six novel molecules containing up to three cyclopentadienyl groups {e.g. 1,3,5-C6H3[OSiMe2(C5Me4H)]3). The dynamic behavior of 1,4-C6H4[OSiMe2(C5H5)]2 (2) was investigated by temperature-variable 1H NMR and the reaction rate of the degenerate 1,2-silicon shift determined. C6H5OSiMe2(C5H5) (1) and (2) were treated with NaH, (MeCN)3M(CO)3 (M = Mo, W), and Mel to give the η5-complexes C6H6OSiMe2 - (C5H4)M(CO)3Me (8: M = Mo, 9: M = W) and 1,4-C6H4[OSiMe2-(C5H4)M(CO)3Me]2 (10: M = Mo, 11: M = W) in good yields. The X-ray crystal structure of 11 was determined.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 160
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2223-2225 
    ISSN: 0009-2940
    Keywords: Lithium, two-coordinate ; Lithium-nitrogen heterocycle ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [LiN(SiMe3)Ar]2 (1, Ar = 2,6-iPr2C6H3) is prepared by the reaction of HN(SiMe3)Ar with nBuLi in n-hexane. This compound with an unusual structure contains a four-membered [LiN]2 heterocycle with two solvent-free two-coordinate Li centers. Its molecular structure represents the first solid-state X-ray analysis of an uncomplexed [LiN]2 dimer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 161
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2249-2254 
    ISSN: 0009-2940
    Keywords: Vanadium alkoxides ; Haptens ; NMR, 51V ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several new oxovanadium alkoxides and alkoxides/chlorides of the composition VOCl3-n(OR)n (n = 1, R = CPh3; n = 2 and 3, R = CPh3, iBu, cyclopentyl, tert-pentyl, octyl; n = 3, R = dodecyl, 3-methylbutyl) and the mixed ester VO(OiBu)- (OCPh3)2 have been prepared. The compounds VO(OiBu)2OR' have been synthesized, where R' is a functionalized long-chain alkyl group [  -  (CH2)8OH,  -  (CH2)6NH(FMOC),  -  (CH2)6NH2,  -  C(O)(CH2)5C(O)OMe, p-C6H4CN, p-C6H4NH2]. The chloride/carboxylate VOCl2{O2C(CH2)5CO2H} has also been obtained. The compounds are characterized, inter alia, by 51V-NMR spectroscopy. Typical 51V shift ranges are observed for specific ligand functionalities (chloride, alkoxide, carboxylate). δ(51V) values also depend on the steric requirement of the groups R and the coordination number. The importance of the functionalized esters as potential triggers for the production of abzymes with phosphatase activity is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 162
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2265-2277 
    ISSN: 0009-2940
    Keywords: Inositol ethers ; Mesogens ; Liquid crystals, thermotropic ; Hydrogen bonding ; Supramolecular structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Liquid-Crystalline Properties of myo- and scyllo-Inositol Multi EthersSelectively alkylated myo- and scyllo-inositol ethers were obtained by multi-step syntheses starting from commercially available myo-inositol. Necessary conversions of axial hydroxy groups into equatorial ones were achieved using either potassium superoxide (KO2) or potassium nitrite (KNO2) as oxygen nucleophiles for the transformation of myo- into scyllo- inositol derivatives. Polarizing microscopic and thermoanalytical studies of numerous members of three families (6, 13, and 20) of inositol ethers reveal for most of them thermotropic liquid-crystalline behavior. Furthermore, in case of the two long-chain scyllitol tetraethers 13d and e an unusual thermopolymorphism has been found. The number, position, and stereochemical arrangement of alkyl chains attached to the inositol cores strongly influence the mesogenic properties of these biomolecule derivatives, chemically vicinal diols and tetrols. The self-assembly of the studied inositol multi ethers to columnar mesophases of “supramolecular structures” is discussed considering geometrical features of these molecules and their capabilities to aggregate by hydrogen bonding.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 163
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 345-352 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The near-ultraviolet spectrum of a dinaphthonorbornadiene is reported and is interpreted using simple exciton theory that treats this molecule as a dimer of naphthalene. It shows examples of weak, intermediate, and strong coupling for the interaction of the three observed bands of naphthalene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 164
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 387-397 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coherent dynamics of multilevel systems is of interest for the elucidation of energy disposal and multiphoton chemistry of polyatomic molecules. We compare the analytical solutions for coherent multiphoton excitation of two sparse multilevel model systems: (1) The spin-J system consisting of N = (2J + 1) equally spaced levels with the radiative coupling being determined by the xth component of the angular momentum. (2) The equally coupled N level system. The transition amplitudes for system (1) are always periodic, which is in contrast to the nonperiodic behavior exhibited by system (2) for N 〉 3.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 165
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 437-447 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A formulation is presented of the effects of van der Waals interaction on infrared intensities. The theory takes account of induction and dispersion interactions (including charge interpenetration) and is applicable to fluids of arbitrary density. The transition moments are developed from generalized van der Waals-induced moments, and expressions are obtained for the adsorption coefficient in terms of generalized charge densities and charge-density (hyper)susceptibilities. Explicit expressions are given also of the integrated absorption coefficient in terms of multipoles, and (hyper)polarizabilities and their derivates, and the usefulness of this formulationin interpreting experimental data is illustrated by several examples. The relevance of the induction and dispersion interactions to allowed and to forbidden transitions made allowed is discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 166
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 455-486 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction between theory and experiment in the field of molecular core electron spectroscopies is reviewed. Those aspects that distinguish the theoretical descriptions of core and valence electron spectra are analyzed in particular. Differences in the theoretical approaches to atomic and molecular spectra in terms of scattering and many-body theories are commented on. The molecular core electron spectroscopies are analyzed from a common point of view with respect to molecular orbital theory, many-body theory, and the role of localization and local selection rules. A brief analysis is presented for the particularities that enter the calculations of core hole spectra. Solutions are described to computational problems posed by the quasi-bound, highly excited nature of core hole states and by the large electronic relaxation following their creation. Two areas where the interaction between theory and experiment is particularly fruitful are briefly reviewed, namely, the theory of vibronic excitations in core electron spectra and the theory of the core photoelectron chemical shift.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 167
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 585-592 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A non-local generalization K(r, r') of the kinetic energy t(r) such that t(r) = ∫K(r, r') dr' is defined using the idempotency property of the Hartree-Fock first-order density matrix. This is, in turn, related by means of an explicit differential equation to the non-local exchange energy density X(r, r'). The relationship is illustrated for a couple of examples: with the Fermi-hole in a uniform electron gas, of importance in the local density version of density functional theory, and with inhomogeneous electron systems.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 168
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 605-613 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total energies, in the Hückel theory, of a large number of polyhex molecules and some containing a four-membered ring have been calculated and analyzed. The results confirm that within a set of isomers the number of Kekulé structures is the dominant variable. It is proposed that this term should be recognized as the aromatic term. The remaining contributions to the energy can be attributed to local features of the molecule. Comparison with the Hess-Schaad analysis of the same energies indicates that this treatment is simpler, more complete, and closer to the original concept of aromaticity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 169
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 170
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 11-17 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The common quantum mechanical problem for the total class of saturated hydrocarbons has been stated and solved within the framework of the effective Hamiltonian method. A quantum mechanical substantiation of the transferability of the electronic structure characteristics (bond dipole moments, bond energies, and bond force constants) as well as the investigation of the origin of transferability have been considered for the stated class of chemical compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 171
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 59-70 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simple net sign analysis has been carried out for particle in one- and two-dimensional boxes and harmonic oscillators. The conclusion that no simple rule for the ordering of eigenvalues of two-dimensional systems can be drawn is conjectured. Cyclobutadiene, naphthalene, benz-cyclobutadiene, biphenylene, biphenyl, and p-terphenyl are found to behave topologically as particle in either type of potential. Benzene, anthracene, naphthacene, and pentacene are found to behave topologically as particle in a two-dimensional harmonic oscillator. This analysis provides the physical basis for the net sign approach in the signed graph theory.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 172
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 123-130 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We propose a fomula that directly gives an estimate of the value of a Gaussian integral through only one multiplication. Using this formula, we may neglect about 60%-80% of integrals in quantum chemical ab initio calculations, without any loss in precision theoretically. Such a large molecule as ATP with 183 STOS using the STO-2G method has been calculated utilizing this technique, and only 31 CPU hours of VAX 11/730 were spent on integrals.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 173
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 163-172 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A basis set of evenly spaced S-type Gaussian functions with common exponents is examined. Formulas for common one- and two-electron integrals are derived. Because of thesymmetry of this basis set, a very compact two-electron integral list is produced. The number of two-electron integrals that must be stored is approximately eight times the number of basis functions. Use of this basis set in an SCF calculation is examined. Numerical results show that this approach works well for molecules containing only small atoms such as hydrogen, helium, or lithium, but that the method has problems with the core orbitals of heavier atoms. Procedures for augementing this basis set in calculations involving heavier atoms are examined.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 174
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 227-228 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 175
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 231-231 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 176
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The correlated, size-consistent, ab initio effective valence-shell dipole operator (μv) method is used to calculate dipole moments and transition dipole moments of the CH molecule and transition dipole moments of the CH+ ion as a function of internuclear distance. The dipole and transition dipole moments computed here compare well with those of other accurate ab initio methods. The transition dipole moments are then used to calculate oscillator strengths and radiative lifetimes for the A → X and B → A transitions of the CH+ ion and the A → X transition of the CH molecule. Comparisons are made with the best available theoretical and experimental lifetimes. Finally, the CH ground-state dipole moment function is used to evaluate overtone intensities and to examine simple models of the CH overtone intensities in polyatomic molecules.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 177
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 299-308 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mulliken's model for the intensity of charge-transfer absorption bands in donor/acceptor complexes is extended to transition-metal compounds. Attention is focused on the analysis of systems containing a central metal ion and symmetrically equivalent π-acceptor ligands. The theory is illustrated for a one-donor/two-acceptor complex in D2d point symmetry. Results are stated for symmetries of commonly occurring transition-metal compounds that display well-documented metal-to-ligand charge-transfer transitions.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 178
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 325-330 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Drawing on the results of an analysis of the nature of the pulse that generates complete transfer of population from one to another level in a system with a discrete spectrum, a generalization of the method of stimulated emission pumping is proposed. It is shown that a small subset of the Fourier components of the optimal pulse will, if their relative amplitudes are the same as in the optimal pulse, generate almost as efficient a population transfer, thereby generating the opportunity to prepare a system in a selected state with a selected population.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 179
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 309-324 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Model studies are reported aimed at accounting for the abrupt dependence of radiationless decay-rate constants on excess energy (known as channel-three decay in the case of S1 benzene) in singlet and triplet manifolds of benzene and azabenzenes. The favored model involves La(ππ*) state, strongly distorted along an out-of-plane coordinate, crossing the ground-state potential at an energy close to the minimum of the lowest excited state. The results are compared with experimental observations on benzene and three azabenzenes. Implications for photochemical reactions are also discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 180
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 353-370 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper, the density matrix formalism has been applied to treat ultrafast time-resolved absorption spectroscopy. We have shown that in the femto-second (fs) pump-probe experiments, the observed time-resolved absorption spectra consist of the contributions from the population (i.e., incoherent contribution) and the coherence (i.e., the phase of the system). The adiabatic approximation has been used to derive the expressions for ultrafast time-resolved spectra. We have also shown that the dynamics of the coherence will result in quantum beat. Numerical calculations have been performed to demonstrate the theoretical results.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 181
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 411-422 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C6H6 Raman scattering activities calculated from harmonic model ab initio Hartree-Fock 6-311 ++ G(d, p) polarizability derivatives (and harmonic force fields calculated at the same level) accurately simulate experiment (to within 1% for the a1g modes). Accurate predictions are also made for the e2g modes (to within 5% for ν7 and ν9, and more poorly for ν6 and ν8 [in Fermi resonance with ν6 + ν1]) and for the e1g out-of-plane mode, ν10. Only the ν6 in-plane CCC bending mode scattering activity is found to be anomalous. Systematic variation of the basis set indicates that the benzene scattering activities and depolarization ratios are strongly dependent on inclusion of both carbon and hydrogen atom diffuse functions in the basis set. Predictions are also made for 12C6D6 and for unmeasured intensities in 13C6H6. Measurements of a1g mode scattering activities in the latter molecule are predicted to be useful in testing the harmonic Hartree-Fock Raman intensity model.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 182
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 347-360 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Any matrix can be expanded on a basis of SU(2) normalized irreducible tensorial matrices, NITM, defined in terms of 3-j symbols or coupling coefficients of SU(2). The NITM transform under rotations according to Wigner's matrices. If one dimension of an NITM is odd and the other even, the tensor has half-integer rank. A simple NITM basis consists of all NITM having the same numbers of rows and columns as the expanded matrix. A compound NITM basis consists of two or more simple bases, each spanning a corresponding block in the expanded matrix. The choice of NITM basis for expanding an effective Hamiltonian matrix is a crucial step in formulating a model. To illustrate the use of a compound NITM basis, including nonsquare NITM, an effective sp-type overlap-free superposition Hamiltonian is constructed and applied to the photoelectron ionization potential spectrum of water.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 183
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 409-414 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a recent work, Csvinszky formulated a variational density-functional approach for the investigation of the spatial generalization of Kato's theorem by March. In the previous work, a 10-electron model system (filled K and L shells) was considered. In the present work, the investigation is extended to two other cases: a 28-electron model system (filled K, L, and M shells) and a 60-electron model system (filled K, L, M, and N shells). As in the previous work, several expressions are adapted for the kinetic-energy functional of the electrons and the intriguing question of identifying the “best” kinetic-energy functional is raised and discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 184
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 421-428 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new type of correlation functional derived from the second-order expression for the correlation energy of an atom is proposed. The derived correlation potential contains one free parameter, which is determined by fitting the known pair correlation energy. The calculations with this potential in the Kohn-Sham approximation give rather accurate values for the matrix elements of different operators.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 185
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 457-473 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the Heisenberg Lie algebra of the nondegenerate harmonic oscillator leads to a basis {J+, J0, J-} of LASU(2). The Hamiltonian of the system is proportional to J0, and the basis elements give rise to irreducible tensors in the associative enveloping algebra of the Heisenberg Lie algebra. The construction of these irreducible tensors is studied with special attention being paid to the case in which they act upon a single vector space spanned by the harmonic oscillator basis functions. A tensor coupling rule is developed, and useful application is made of it in the calculation of general expressions for vibrational operators and their matrix elements. Throughout, the value of the additional algebraic quantum numbers (l, m) is emphasized.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 186
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 501-510 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In excited states of atoms and molecules, as well as in time-dependent situations, the one-electron density no longer suffices to completely characterize the electronic state; in addition, one now requires information about the electronic phase or the current density. We show that, for a stationary electronic state, the continuity equation of quantum fluid dynamics represents a differential equation for the electronic phase, which must be solved subject to certain periodicity conditions. These periodicity conditions arise from the nodal topology of the wave function and give rise to quantized vortices of current. The consequences of writing an electronic “wave function” for a many-electron system directly in terms of the single-particle density and phase have been investigated. We have shown that such a procedure leads to the appearance of an “internal magnetic vector potential.” We also establish the connection between the electronic phase and the geometrical (“Berry”) phase accompanying the adiabatic transport of a quantal system around a closed loop in parameter space. This leads to a generalization of the current density concept and allows us to discuss the geometrical phase in terms of the circulation of this current in parameter space.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 187
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 188
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 39-45 
    ISSN: 0009-2940
    Keywords: 1,3,2,4,6-Dithiatriazines ; CNS Polycycles, structure determination ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of Alkenes to 5-(Trifluoromethyl)-1,3,2,4,6-dithiatriazinesDechlorination of 1,3-dichloro-5-(trifluoromethyl)-1,3,2,4,6-dithiatriazine (1) with Ph3Sb gives (CF3CN3S2)n (2) in quantitative yield. By 1,3-addition of alkenes (dicyclopentadiene, cyclopentene, cis- and trans-2-butene, propene, and ethene) to 2 the corresponding penta- (4a), tri-(5a), and bicyclic ring systems 6a, 6b, 7, 8a, 8b, and 9 are prepared in 65-85% yields. The molecular structures of 6a and 7 were determined by single-crystal X-ray analysis; the other structures were derived from NMR data. The NMR analyses are in accordance with MNDO calculations. For 4a and 5a only the thermodynamically favoured anti-isomers are found, as expected from these calculations; for 6 and 8 they show satisfactory agreement for anti/syn-proportions as determined by NMR spectroscopy. The product distribution corresponds to a symmetry-allowed alkene addition to a singlet dithiatriazine.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 189
    ISSN: 0009-2940
    Keywords: Sulfur diimides ; 1,3-Cycloaddition, reductive ; 1,2,4,3-Thiadiazaboretidines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of 1,2,4,3-Thiadiazaboretidines. Crystal Structure of 2,4-Di-tert-butyl-3-phenyl-1,2,4,3-thiadiazaboretidineReaction of sulfur diimides with alkyl(aryl)bis(methylthio)boranes leads to reductive 1,3-cycloaddition of the NSN sequence with formation of the 1,2,4,3-thiadiazaboretidines 2a-g. NMR (1H, 11B, 13C, 15N, 29Si), mass spectra and the results of the X-ray analysis of 21 are reported and discussed. The 11B chemical shifts have been calculated for 3-phenyl-1,2,4,3-thiadiazaboretidine and some related model compounds by the IGLO method and correlate acceptably with the experimental values.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 190
    ISSN: 0009-2940
    Keywords: Metal atom synthesis ; Clusters ; Electrochemistry ; Cyclic voltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Atoms in the Synthesis of Metal Clusters, II1). - Reactions of Substituted Cyclopentadienes and Nickelocene with Nickel and Iron AtomsBy vaporizing nickel atoms into solutions of tert-butyl-substituted cyclopentadienes in methylcyclohexane mononuclear sandwich compounds (1, 4, and 6 as main products) as well as tri- and tetranuclear clusters are prepared. With mono- and di-tert-butyl-substituted cyclopentadienes as ligands the new clusters 2 and 5 are obtained. In the reaction with 1,2,4-tri-tert-butylcyclopentadiene 6 is the only observed product. Hindered rotation around the metal-ligand bond vector is observed for 4 even at room temperature. When treating 1 with nickel atoms cluster 2 is formed, indicating some importance of 1 during the formation of 2 in the above reaction. Clusters 2 and 5 contain hydrido ligands, which could be identified in the case of tris(1,3-di-tert-butyl-η5-cyclopentadienyl)trinickel dihydride (5) by a single crystal structure determination as μ3-H bridges. A tetrahedral structure is found for the cluster 2 by X-ray crystallography. With the aid of MS, IR, magnetic measurements, and cyclovoltammetric investigations 2 is identified as a mixture of 2a and 2b bearing one or three bridging hydrogens, respectively. In general 2a, 2b, and 5 show a rich redox chemistry with reversible redox couples between -2 and +2. Reaction of iron atoms, nickelocene, and mesitylene in methylcyclohexane at -120°C leads unexpectedly to cluster 3, tetrakis(η5-cyclopentadienyl)tetranickel trihydride and a not yet identified (η5-cyclopentadienyl)mesityleneiron complex. Possible formation routes for 1-6 are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 191
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 333-336 
    ISSN: 0009-2940
    Keywords: Phosphine ligand ; Anthracene ; Nickel(II) complexes ; Palladium(II) complexes ; Cyclometallated chelate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 4 was synthesized from dipotassium 1,8-anthracenedisulfonate (9) and potassium diphenylphosphide (Ph2PK). On reaction of 4 with nickel(II) chloride and bis-(benzonitrile)palladium(II) chloride, cyclometallation of the C - H bond in anthracene 9-position led to the square-planar chelate complexes 11 and 13, respectively. In the case of the palladium complex 13, the cyclometallated structure was proved by X-ray structure analysis. Treatment with aqueous potassium cyanide did not remove nickel from 11, but converted 11 into 12 by substitution of chloride with cyanide, demonstrating the high stability of these cyclometallated chelate complexes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 192
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 353-356 
    ISSN: 0009-2940
    Keywords: Benzocyclopropene ; 1,3-Dihydroisobenzofurans ; Yb(fod)3 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experiments Concerning the Reactions of Benzocyclopropene under Yb(fod)3 Catalysis1,3-Dihydroisobenzofuran derivatives 3a - e and 5a - c are obtained by reactions of α,β-unsaturated carbonyl compounds with benzocyclopropene (1). The yields increase by addition of Yb(fod)3. Aromatic aldehydes react in the same way. Yb(fod)3 has no influence on the reactions of α,β-unsaturated hydrazones with 1.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 193
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 357-363 
    ISSN: 0009-2940
    Keywords: Heterodiynes, medium-sized ; [2.2](2,5)-Thiophenophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Heterocyclic Diynes and their Reaction with CpCo(CO)2The preparation of the heterocyclic diynes 1,6-dithia-3,8-cyclodecadiyne (1b), thia-3,8-cyclodecadiyne (11), 1-thia-6-selana-3,8-cyclodecadiyne (12), oxa-3,8-cyclodecadiyne (13), 1,6-dioxa-3,8-cyclodecadiyne (14), 1-oxa-6-thia-3,8-cyclodecadiyne (15), 1,6-diselena-3,8-cyclodecadiyne (26), thia-3,9-cyclounde-cadiyne (22a), thia-3,13-cyclopentadecadiyne (22b) and its selena analogues 23a, 23b is described. The thia and monoselena compounds are obtained by a thia- or selenacyclization of the corresponding dibromides. Compound 26 has been obtained by a Misumi coupling reaction. The thiacycloalkadiynes of medium-sized rings (10, 11) react with CpCo(CO)2 to yield [2,2](2,5)thiophenophane derivatives. Acyclic thiadialkynes or thiacycloalkadiynes of larger ring size (22b) with CpCo(CO)2 by [2 + 2 + 2] cycloaddition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 194
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 387-390 
    ISSN: 0009-2940
    Keywords: Peroxy compounds ; Cobaloximes ; Oxygen insertion ; Radicals, alkoxy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkoxy radicals have been generated by photochemical reactions of (alkylperoxy)cobaloximes 1. The occurrence of alkoxy radicals has been proved by characteristic cyclization and β-scission reactions of the reactive intermediates.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 195
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 271-274 
    ISSN: 0009-2940
    Keywords: Phosphacumulenes ; Cumulenes ; Calculations, MNDO, SCF ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound phosphabutatriene possesses two energetically closely spaced frontier orbitals, as in methylenephosphane and in phosphaallene. They are built up from the π system or the s̰ orbital of phosphorus by interaction with neighboring π bonds. The extension of these frontier orbitals over all (heavy) atoms makes self-dimerization to different cyclobutane derivatives feasible. Substituent effects on the ordering of s̰ and π are analyzed. Vibrational analyses indicate P=C vibrations of low intensity which decrease with increasing length of the heterocumulene chain. The analysis is extended to the two next higher homologs, which are hitherto experimentally unknown.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 196
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 227-232 
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxiranes ; Ketones, α,β-unsaturated ; (E)-Chalcones ; (E)-2′-Hydroxychalcones ; 2-Cycloen-1-ones ; Caroate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of epoxides 3a - r is achieved in excellent yields by reaction of the α,β-unsaturated ketones 1a-c, 4,4′-disubstituted (E)-chalcones 1d-o, and 2′-hydroxy-4-substituted (E)-chalcones 1p - r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl)dioxirane (2b). This method constitutes a useful alternative to the Weitz-Scheffer epoxidation (alkaline H2O2) of such electronpoor substrates.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 197
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 241-245 
    ISSN: 0009-2940
    Keywords: 2-Norbornyl cations, 5,5,6,6-tetramethyl- ; Tetracyclo[4.2.2.12,5.01,6]undec-3-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 5,5,6,6-Tetraalkyl-2-norbornyl CationsWhen the 6,6-dimethyl-2-norbornyl cation (9) is generated from the tosylhydrazone 5 by way of the diazonium ion 8, a 2H label is distributed equally between positions 1 and 2 of the exo-alcohol 10. The degeneracy of 9, previously derived from solvolytic studies, is thus confirmed for the deaminative route. 5,5,6,6-Tetramethyl-2-norbornanone (25) and tetracyclo[4.2.2.12,5.01,6]undecan-3-one (31) are prepared by using Diels-Alder methodology. The corresponding tosylhydrazones 26 and 32 are employed as precursors for the 5,5,6,6-tetramethyl-2-norbornyl and tetracyclo[4.2.2.12,5.01,6]undec-3-yl cations (11 and 12). Again, the distributions of 2H labels are close to 1 : 1. The angular distortions expected from repulsive interactions of the methyl groups in 11 and from cyclobutane annulation in 12 do not affect the relative energies of the bridged ions.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 198
    ISSN: 0009-2940
    Keywords: (η2-Alkene)(η5-cyclopentadienyl)organylnickel(II) complexes, stability and reactivity of ; Cyclopentadienyl ligands, substituted ; Chelating alkenylcyclopentadienyl ; Nickel complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various Coordinations in (η2-Alkene)(η5-cyclopentadienyl)organylnickel(II) ComplexesA series of (η2-alkene)(η5-cyclopentadienyl)organylnickel(II) complexes with substituted cyclopentadienyl ligands is synthesized in order to compare the structures, the thermal stabilities, and chemical reactivities. In (allyl)(η5-Cp')Ni compounds the allyl moiety is η3-coordinated when Cp'=C5H5, C5Me5 (1), C5Ph5 (2), indenyl (3), [Hydridotri(pyrazolyl)borato] (4) (as an equivalent of the cyclopentadienyl ligand), and [C5H4((CH2)3CH=CH2)] (22). It is found that the [(η2-alkene)alkyl(η5-Cp')nickel] compounds [Cp'=C5Me5; alkene=C2H4, alkyl=Me (10), Et (9) or alkene=(1 - 2-η2)-1,3-butadiene, alkyl=Me (11); Cp'=C5Ph5; alkene=C2H4, alkyl=Me (12)] are thermally more stable and less reactive than their η5;- C5H5 analogues; the largest increase in thermal stability is observed when the η5-Cp' and the η2-alkene functions are connected by substitution of the cyclopentadienyl ligand with an alkenyl group of suitable chain length. In the case of compounds of the general type [(η5-C5R4((CH2)nCH=CH2))-(ligand)Ni(II)] with Ph3P as the ligand these complexes are cationic [R=H, n=3 (14+) or R=Me, n=2 (17+)]. On the other hand, the compounds with anionic ligands are neutral complexes (R=H, n=3, ligand=methyl (19), ethyl (20), isopropyl (21) or R=Me, n=3 and ligand=iodide (24), bromide (25), methyl (26), ethyl (27)]. In 14+, 17+, 19 - 21 and 24 - 27 the C=C bond of the alkenyl group is η2-coordinated to the nickel atom. X-ray structures have been determined for 4 and 25.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 199
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 481-486 
    ISSN: 0009-2940
    Keywords: Tris[3-(2,3-dihydroxyphenoxy)propyl]amine hydrochloride containing ; 99mTc uptake ; Technetium, radiopharmaceutical ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Chelates of Medical Interest, I. - 99mTc Complexes with Hexadentate Tricatechol LigandsThe tricatechol ligand tris[3-(2,3-dihydroxyphenoxy)propyl]-amine hydrochloride, TRIPACE (9), is prepared from tris(3-chlorpropyl)amine (5) and the potassium salt of 2,2-dimethyl-1,3-benzodioxol-4-ol (7). This ligand is capable of reducing the 99m[TcO4]- ion to lower valent 99mTc and subsequent complexation of the reduced 99mTc ion. The structures of 5 and of tris[3-(2,2-dimethyl-1,3-benzodioxol-4-yloxy)propyl]amine (8) are determined by X-ray diffraction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 200
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 515-517 
    ISSN: 0009-2940
    Keywords: Manganese complexes ; Aggregation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influencing the Aggregation of Manganese Complexes by Different Bases: Formation of [Mn(O2CCF3)2(py)4] and [Mn3(O2CCF3)6(benz)6]Manganese powder reacts quantitatively with trifluoroacetic acid to yield Mn(O2CCF3)2 (1). The aggregation of 1 is directed by different N-containing bases. Pyridine (py) forms the mono-nuclear complex [Mn(O2CCF3)2(py)4] (2), while benzonitrile (benz) yields the trinuclear complex [Mn3(O2CCF3)6(benz)6] (3). The X-ray structures of 2 and 3 are described.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...