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  • 2020-2022
  • 1990-1994  (1,011)
  • 1985-1989  (861)
  • 1850-1859
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  • 201
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 523-526 
    ISSN: 0009-2940
    Keywords: Titanium complexes ; Short bonds, Ti - N ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of [Dimethylamino(thiocarbonyl)thioamido]titanium(IV) Dihalides - Compounds with Short Ti - N BondsReaction of Me2NC(S)SN(SiMe3)2 (1) with TiCl4 and TiBr4 yields (2) and (3). Treatment of 2 and 3 with pyridine (py) leads to the solvates · 3 py [2a (X=Cl), 3a (X=Br)]. These adducts have been characterized by X-ray structure determination.
    Additional Material: 1 Ill.
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  • 202
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 551-561 
    ISSN: 0009-2940
    Keywords: Conformational analysis ; Spiro[4.5]decanes ; Allylboration, transition state models ; Ketals, chiral, cleavage by Lewis acids ; Calculations, MNDO and SYBYL ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behaviour of 10-X-substituted 1,4-dioxa-and 1,4,6-trioxaspiro[4.5]decanes 1 - 4 has been studied by 13C-, 19F- and 1H-NMR spectroscopy. Two X-ray analyses (of 2a,e) are presented, and their implications to cleavage reactions of chiral acetals are discussed. Participation of twist boat forms in the conformeric equilibrium of at least 1c has been made plausible by observing 13C,19F-NMR coupling constants. The ratios of axial to equatorial conformer in 1 - 4 have been calculated by molecular mechanics.
    Additional Material: 2 Ill.
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  • 203
    ISSN: 0009-2940
    Keywords: Manganates, carbonyl, trinuclear ; Indium-manganese clusters ; Spiro cluster ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Trinuclear Carbonylmanganates and Their Reaction Products with InCl3; X-ray Structure Determinations of K3[Mn3(μ-CO)2(CO)10], [(C6H5)4As]2[(μ-H)Mn3(μ-CO)10], [{(C6H5)3P}2N]2[μ-H)Mn3(CO)12], [(C6H5)4As]2[{μ-H)Mn3(CO)12}2(μ4-In)] und [(C6H5)4As]2[{(μ-H)Mn3(CO)12}(μ3-In){Mn(CO)5}Cl]Mn2(CO)10 reacts with KOH in aqueous solution to give the potassium carbonylmanganate K3[Mn3(μ-CO)2(CO)10] (1). The trianion 1 is isoelectronic with Fe3(CO)12 and is protonated with methanol to form the μ-hydrido cluster [(μ-H)Mn3;-(CO)12]3⊖, which is precipitated with [{(C6H5)3P}2N]Cl as [{(C6H5)3P}2N]2[(μ-H)Mn3(CO)12] (2), whereas the carbonyl-bridged μ-hydrido species [(μ-H)Mn3(μ-CO)2(CO)10]2⊖ seems to be trapped as the [(C6H5)4As]⊕ salt 3. The reaction of 3 with InCl3 yields the Mn-In clusters [(C6H5)4As]2[{(μ-H)Mn3(CO)12}2;-(μ4-In) (4) and [(C6H5)4As]2[{(μ-H)Mn3(CO)12}(μ3-In){Mn(CO)5}Cl] (5). X-ray structure analyses have been carried out for the compounds 1 - 5.
    Additional Material: 7 Ill.
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  • 204
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 493-496 
    ISSN: 0009-2940
    Keywords: Phosphaalkene ethers ; 1,3-Oxaphospholes, dihydro- ; 1,3-Oxaphosphorines, tetrahydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New σ2λ3-P=C - O Systems: Stable Non-Conjugated Phosphaalkene Ethers - Synthesis and ReactivityNon-conjugated cyclic phosphaalkene ethers (2, 4, 6) are obtained by cyclocondensation of (2- or 3-hydroxyalkyl)phosphanes 1, 3 with N-arylpivalimidoyl chlorides. Hydrolysis of 2, 4 with H2O (→7, 8), addition of hydrogen compounds (HCl, HSPh, MePhPH) (→ 9-12), and oxidation with air (→ 14) are studied. The reactivity of the title compounds and of benzoxaphospholes are compared.
    Additional Material: 1 Tab.
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  • 205
    ISSN: 0009-2940
    Keywords: cis;-2-Boryl-1-stannylalkenes ; Addition reactions ; Exchange reactions ; Solvent-controlled reactions ; Tin - Element bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Behaviour of cis;-2-Boryl-1-stannylalkenes Against (Dimethylamino)trimethylstannane, Methoxytrimethylstannane, and Methanol - Formation of New Tin - Element Bonds, Examples of Solvent-Controlled ReactionsWhen alkene derivatives1 [Me3Sn(R1)C=C(R)BR2], with the trimethylstannyl- and the dialkylboryl group in cis position at the C=C double bond, are treated with (dimethylamino)-trimethylstannane (4), methoxytrimethylstannane (5), or methanol, the product distribution depends remarkably on the solvent [hexane or tetrahydrofuran (THF)]. In hexane, 1a, b (R1=H, R=Et, Pr) react with 4 to give the B-dimethylamino compounds 6a, b in high yields as a result of addition and rearrangement. Other derivatives 1 do not react with 4 in hexane. Under the same conditions in hexane some alkenes 1 react with 5 to yield the B-methoxy derivatives 8, which are analogous to 6. A complex mixture of various products is obtained from the reaction of 1 with methanol in hexane. If the same reactions are carried out in THF, many compounds 1 react with 4 and 5 to eliminate tetramethyltin and give dihydro- 1,2,5-azonia- (7) or dihydro-1,2,5-oxoniastannaboratoles (9), respectively. The reaction with methanol in THF also leads to the oxonia-stannaboratoles 9, this time by elimination of methane. Pure samples of compound 9g are obtained as the crystalline THF adduct 9g-THF. A mechanism is proposed involving adduct formation at the boryl group, followed by intramolecular reactions depending on the donor quality of the respective solvent.
    Additional Material: 1 Ill.
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  • 206
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 671-672 
    ISSN: 0009-2940
    Keywords: Azines ; Bis(azines) ; Macrocycles ; Tetraazapolyenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new macrocyclic bis(azine) 2 forming yellow microcrystals has been prepared in 72% yield by treating the diketone 1 with hydrazine hydrate under high-dilution conditions. In contrast to the UV/Vis spectrum of the “open-chain” azine 4, that of 2 shows characteristic features of a polyene chromophore containing (Z)-configurated double bonds.
    Additional Material: 1 Ill.
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  • 207
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 683-689 
    ISSN: 0009-2940
    Keywords: Metallacycles ; Titanium complexes ; Vanadium complexes ; Chromium complexes ; Amides, silylated ; Electrochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic Metal(IV)AmidesSynthesis and structure of cyclic amide complexes of quadrivalent titanium, vanadium, and chromium are described, and their electrochemical behavior is investigated by cyclic voltammetry. The novel amides of formula ML2 {M=Ti, (3b); M=V, (3c); M=Cr, (3d); L=[(CH3)3SiNCH2CH2NSi(CH3)3]} are formed by reaction of the halide adducts MCl3(THF)3 with the dilithium salt Li2L with concomitant disproportionation. Formation of 3d proceeds via the complex [3 d]⊖ and requires additional oxidation with oxygen or iodine. An X-ray crystalstructure determination of 3b reveals the titanium atom in strongly distorted tetrahedral environment with approximate symmetry D2d. The amide complexes 3b -d are monomeric, thermally stable, and sublime readily without decomposition; they are very sensitive to water and soluble in all common organic solvents.
    Additional Material: 3 Ill.
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  • 208
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 707-712 
    ISSN: 0009-2940
    Keywords: Osmium mesitylene complexes ; Os - R bonds, formation of ; Osmium aryl hydrido compounds ; Cyclohexene, generation from C6H11MgX ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of [(Mes)Os(CO)Cl2] (3) with PhLi in benzene gives the diphenylosmium compound [(Mes)OsPh2(CO)] (6) whereas with PhMgBr [(Mes)OsPh(CO)Br] (7) is obtained. Treatment of 3 with TolMgBr in benzene or ether affords almost exclusively the monoaryl complex [(Mes)OsTol(CO)Br] (8). Compound 3 reacts with C6H11MgCl to give both [(Mes)Os(C6H11)2(CO)] (9) and [(Mes)Os(C6H10)(CO)] (10) in 60 and 30% yield, respectively. With C6H11MgBr, complex 10 is mainly obtained. Reaction of 7 and 8 with Na/Hg in THF/EtOH gives nearly quantitatively the arylhydridoosmium complexes [(Mes)Os-C6H4R(CO)H] (14, 15). The analogous hydrido methyl compound [(Mes)OsCH3(CO)H] (13) reacts with CCl4 to produce [(Mes)OsCH3(CO)Cl] (17), which is not accessible from 3 and LiCH3 or CH3MgX. The X-ray structure analysis of 10 reveals that the cyclohexene is coordinated in the endo configuration.
    Additional Material: 1 Ill.
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  • 209
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 753-756 
    ISSN: 0009-2940
    Keywords: Metal chelates ; Tetrachloroimidodiphosphates of Al, Ga, In, Sn, Ti ; Metallaheterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Imidodiphosphates of Aluminum, Gallium, Indium, Tin, and Titanium.Me3SiN[P(O)Cl2]2, (1) and Me3SnN[P(O)Cl2]2 (2) are synthesized from NaN[P(O)Cl2]2 and Me3SiCl or Me3SnCl, respectively. Treatment of 1 with AlCl3, GaCl3 InCl3, Me2SnCl2, and TiCl4 yields (3), (4), (5), (6), and (7), respectively. Reaction of LiN[P(O)Ph2]2 with TiCl4 leads to (8). NMR spectra demonstrate that the tetrachloroimidodiphosphate ligand coordinates through the oxygen atoms towards the metal atom.
    Additional Material: 1 Tab.
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  • 210
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 757-759 
    ISSN: 0009-2940
    Keywords: Rhenium(VII) ; Aza compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Ph3P=NRe(NC6H3iPr2;-2,6)3 - An Aza-Rhenium (VII) Compound.Ph3PNReO3 (1) reacts with three equivalents of 2,6-diisopropylphenyl isocyanate with evolution of CO2 to give the title compound 2. The X-ray single crystal structure of 2 exhibits a rhenium atom tetrahedrally coordinated to four nitrogen atoms (space group P 3).
    Additional Material: 1 Ill.
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  • 211
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 769-771 
    ISSN: 0009-2940
    Keywords: Silaethene ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reactivity of Silaethene Me2Si=C(SiMe3)2: Stereospecificity of Diels-Alder Reactions with Hexadienes1,2)[4 + 2] Cycloaddition of trans,trans;- and cis,trans;-2,4-hexadiene to silaethene Me2Si=C(SiMe3)2 (1) takes place stereo-specifically in one step with formation of 3 and 4, respectively. In addition, both reactions lead to ene products 5, 6.
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  • 212
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 773-775 
    ISSN: 0009-2940
    Keywords: Alkyne complexes ; Clusters ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of undecacarbonyl(acetonitrile)triiron (1) with 1,4-dimethoxy-2-butyne (2) yields the alkyne complexes decacarbonyl(μ3;-η2-Verbar-1,4-dimethoxy-2-butyne)triiron (3) and nonacarbonyl(μ3;-η2;-⊥-1,4-dimethoxy-3-butyne)triiron (4). The crystal structure determination of 2 shows that the alkyne ligand is coordinated strictly parallel to one iron-iron edge.
    Additional Material: 1 Tab.
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  • 213
    ISSN: 0009-2940
    Keywords: PE spectroscopy ; Lone-pair interaction ; Orbitals, localized ; Orbitals, precanonical ; 1,5-Diketones, polycyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five polycyclic 1,5-diketones 1 - 4 and 6 are synthesized and studied by means of He(Iα) PE spectroscopy. Comparison of the spectra indicates significant differences in Orbital Interaction Through Bond, which is explained by computational methods, especially by analyses of the precanonical MOs. The lone pair splitting observed in diketone 1, ΔI(n)=0.75 eV, seems to be the largest one ever found in a 1,5-diketone, obviously due to a favourable zigzag topology of the σ frame. In addition, coupling reactions and photoreactivity are studied in compound 6, which seemed to be well suited for Orbital Interaction Through Space. The crystal structure of 6 and its photoproduct 21 is solved by X-ray crystallography.
    Additional Material: 4 Ill.
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  • 214
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 827-832 
    ISSN: 0009-2940
    Keywords: Conformations, solid state ; Conformers in solution ; UV-Vis transition energies and CO/CO dihedral angles ; CO/CO rotational barriers ; Calculations, CNDO/S-CI, MMP1, PIMM / PE spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromophoric Systems, 2. - Conformation and Absorption of Light in (2-Alkoxyvinyl)ethanedionesThe unusual color properties of yellow 1,2-bis(4,5-dihydrofuran-3-yl)ethane-1,2-dione (1) and colorless 1,2-bis(5,6-dihydro-4H-pyran-3-yl)ethane-1,2-dione (2) in the solid state and in solution are investigated by crystal structure analysis, UV-Vis, PE, and 13C-NMR spectroscopy as well as by reparameterized force-field calculations. Dione 1 takes an antiperiplaner CO/CO conformation of its chromophore in the solid state whereas dione 2 is twisted in this respect by 102°. In solution both chromophores are not planar, but 1 is less distorted (ca. 142°) than dione 2 (ca. 126°). The calculated rotational barrier for CO/CO twisting amounts to 0.9 kcal mol-1 for 1 and to 2.2 kcal mol-1 for 2.
    Additional Material: 7 Ill.
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  • 215
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 867-873 
    ISSN: 0009-2940
    Keywords: Diels-Alder reaction ; Captodative effect ; Calculations, MNDO-PM3 ; Allenic dienophiles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of captodative (c,d) substitution of some olefins and allenes has been investigated by MNDO-PM3 calculations. These results are compared with the Diels-Alder reactions of α-sulfur-substituted allenecarboxylates. α-Sulfonyl allenecarboxylates 6 are a new class of stable gem-diacceptor-substituted allenes.
    Additional Material: 2 Ill.
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  • 216
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 947-956 
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Alkenes ; α-Oxo- ; 1,2,4-Trioxolanes ; acyl- ; 3,3′-Bi-1,2,4-trioxolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ozonolyses of α-Oxo-alkenes: On the Existence of α-Oxo-ozonidesOzonolyses of nine acyclic (1a-i) and of two cyclic (14, 29) α-Oxo-alkenes on polyethylene or in pentane afforded in eight cases (1d-i, 14, 29) isolable α-Oxo-ozonides. α-Diozonides (9) are obtained from five of the acyclic α-Oxo-alkenes (1a, b, d, g, h). All isolated ozonides are labile; the 2,4-dinitrophenylhydrazones of the α-Oxo-ozonides, however, are very stable. Decomposition of the α-Oxo-ozonides affords not only the hitherto known fragments, but non-peroxidic isomers (8) of the ozonides, too.
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  • 217
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 971-972 
    ISSN: 0009-2940
    Keywords: Isocyanide-cyanide rearrangement ; Bridgehead reactivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steric Hindrance of the Isocyanide-Cyanide Rearrangement in a Bridgehead PositionThe activation barrier of the isocyanide-cyanide rearrangement of 13-isocyano-1,4,5,8,9,12-hexamethyltriptycene (5) is the highest of all known isocyanides. The special position of this compound can be explained by a strong increase of strain enthalpy during the isomerization. This is due to the cage-like inclusion of the isocyano group in the bridgehead position by the methyl groups in the positions 1, 8, and 9.
    Additional Material: 2 Tab.
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  • 218
    ISSN: 0009-2940
    Keywords: Phosphaallyl complexes ; Chalcogenes ; Düron, enneacarbonyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, XV. - Reaction of the Phosphaallyl Complex (η5-C5Me5)(CO)Fe{η3-P[CH(SiMe33)2](CHC=O}} with Chalcogenes as well as with Fe2(CO)9The (η3-phoshaalyl)iron complex (η5-C5Me5)(CO)Fe{η3-P(CH(SiMe3)2](CHC=O)} (1) is oxidized by sulfur and selenium to afford the methylenethioxo- and methyleneselenoxophosphorane complexes 4 and 5 with an anti-configuration of the CH(SiMe3)2 substituent relative to iron. The chalcogene atoms are attached to the phosphorus atom of the ligand and do not participate in the bonding to the metal Equivalent amounts of 1 and Fe2(CO)9 lead to the phosphaalkenyl complex 6 with an Fe - C σ bond. On the other hand, a large excess of Fe2(CO)9 converts 1 as well as 6 into the cluster compound 7 featuring the bridging 1-oxa-4-phosphabutadiene ligand (η5-C2Me5)(CO)2Fe - C(O) - CH=P - CH(SiMe3)2. Constitution and configuration of all compounds have been elucidated by spectroscopic methods (IR, 1H, 13C, 31P NMR, and MS). In addition complexes 5 and 7 have been characterized by single crystal X-ray diffraction analyses.
    Additional Material: 3 Ill.
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  • 219
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 849-859 
    ISSN: 0009-2940
    Keywords: tert-Leucine ; Diazotation ; Butanoic acid, (S)-2-chloro-3,3-dimethyl-, and derivatives ; Aziridinones ; α-Lactams ; Amino acids, α-alkyl-, and esters ; Oxazolidine-2,5-diones ; Circular dichroism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Chiral, Nonracemic Aziridinone (α-Lactam)1,2)(S)-tert-Leucine [(S)-14] is diazotized affording a mixture of the expected α-chloro and α-hydroxy acids (S)-15 and (S)-16 and the rearranged β-chloro and β-hydroxy acids (R)-12 and (S)-11. Separation produces a 51% yield of pure (S)-15 (e.e. ° 97.4%) which is converted via the acid chloride (S)-17 into the α-chloro amides (S)-18a and b (e.e.=99.0 and 95.2%, respectively). On treatment with tBuOK, the latter is converted into the α-lactam (R)-22b (59%, e.e. ° 91.0%, [α°=-293.7), which is accompanied by small amounts of its ring-opening product (R)-23b. Only the α-amino ester (R)-23 a is formed from the α-chloro amide (S)-18a and tBuOK. While the enantiomers of the halo amides 13, 18a, b, 24a, b and of the 3-pentyl esters of the hydroxy acid 16 are separated by GC on chiral columns, the α-lactam 22b and the α-amino esters 23a, b require conversion into separable derivatives without involving the stereogenic center. Thus, alkaline hydrolysis of 22b as well as acidic cleavage of 23 yield the α-amino acids 25 which are cyclized to the oxazolidine-2,5-diones 26 by means of bis(trichloromethyl) carbonate (“triphosgene”). As shown by the high enantiomeric excess of the products derived from (S)-tert-leucine [(S)-14] none of the reactions described results in a considerable degree of racemization. Authentic samples of 11 and 12 are synthesized from the Reformatzky product 21. The absolute configurations of the major enantiomers derived from (S)-14 are based on the retention on chiral GC columns, the signs of optical rotations, and CD spectra. The mechanism of the rearrangement leading to the β-hydroxy and β-chloro acids (S)-11 and (R)-12 is interpreted in terms of a stereospecific 1,2-methyl shift occurring simultaneously with the ring cleavage of the (protonated) α-lactone (R)-2 (R=tBu) which is the crucial intermediate formed in the diazotization of (S)-14.
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  • 220
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1035-1039 
    ISSN: 0009-2940
    Keywords: Titanium complex ; Diazadiene ligand ; Envelope structure ; Benzyl compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diazadiene Complexes of Electron-Deficient Transition Metals: Synthesis, Properties, and Structure of CpTi(diazadiene)ClThe electron-deficient 1,4-diazadiene (DAD) complex CpTi-(DAD)Cl (3), [DAD=1],4-bis(4-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene] is prepared either by reduction of CpTiCl3 (1) with magnesium in the presence of free DAD (2) or by the reaction of 1 with Na2DAD. NMR spectroscopic and X-ray diffraction analysis of 3 indicate that the bonding of the DAD ligand has σ2,π-metallacyclopentene rather than η4;-π character. As a result of steric repulsion between the Cp ring and methyl groups of the DAD ligand 3 exhibits a supine (exo) geometry for DAD coordination is solid state. Substitution reaction of 3 affords the novel complex CpTi(DAD)R (R=CH2Ph).
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  • 221
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Carbenes ; Silaethenes ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: UV photolysis of diazo(pentamethyldisilanyl)methyl ketones 1b - d generates acylsilenes (3-oxo-1-sila-1-propenes) 3 as reactive intermediates, which can be trapped by enolizable carbonyl compounds in an ene-type reaction. With non-enolizable carbonyl compounds or ethyl acetate, they undergo a [4 + 2] cycloaddition. In contrast to the photolysis in the absence of these carbonyl compounds, a Wolff rearrangement of 1b - d (or the derived carbenes) to silyl ketenes 5b - d is observed as a competitive reaction.
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  • 222
    ISSN: 0009-2940
    Keywords: Chalcogen-chalcogen bonds ; Selenium ; Selenide (2,4,6-tri-tert-butylphenyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Properties of Chalcogen-Chalcogen Bonds, XV1). - Lithium 2,4,6-Tri-tert-butylphenylselenide: Synthesis, Structure, and Reactions with Formation of Se - P, Se - C, Se - Si, Se - Sn, and Se - Au BondsBis(2,4,6-tri-tert-butylphenyl)diselenide (1) is reduced by lithium triethylhydridoborate to give lithium 2,4,6-tri-tert-butyl-phenylselenide (2) in high yield. 2 crystallizes with three molecules of tetrahydrofuran coordinated to lithium ([2(THF)3] ≡ 2a, space group P&1macr; Z =4). The monomeric compound 2a contains four-coordinate lithium bonded to two-coordinate selenium. 2 (LiSeR) reacts with the nonmetal and metal halides tBu2PCl, CH2Cl2, Me3SiCl, Me3SnCl, and Ph3PAuCl to give tBu2PSeR (3), RSeCH2Cl (4), (RSe)2CH2 (5), Me3SiSeR (6), Me3SnSeR (7), and the novel gold(I) selenophenolate derivative Ph3PAuSeR (8)(R = 2,4,6-tri-tert-butylphenyl).
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  • 223
    ISSN: 0009-2940
    Keywords: Fluorophosphoranes ; Donor-acceptor interaction ; Azonium salts ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the tetrafluorophosphoranes RPF4 [R = CH3, C6H5, C6F5, (CH3)3SiCH2, and 2,5-(CH3)2C6H3] with N,N,Ń-trimethyl-N′-(trimethylsilyl))ethylenediamine (1) yields the corresponding triflurophosphoranes 2-6 by cleavage of the Si - N bond and elimination of (CH3)3SiF. In an analogous reaction the difluorophosphoranes R1R2PF2N(CH3)CH2CJ2N-(CH3)2 (R1 = R2 = C6H5, 7: R1 = C6H5, R2 = C4H4N, 8) are formed. Some of these N,N,Ń-trimethylethylenediamine-substituted di- and trifluorophosphoranes react with PF5 as a Lewis acid to form the corresponding azonium hexafluorophosphates 9-12 as a result of fluoride abstraction and intramolecular (CH3)2N→P donor-acceptor interaction. Compound 13 shows dynamic behaviour in solution. An exchange process is observed for the axial and equatorial fluorine atoms by 19F- and 31P-NMR spectroscopy. An X-ray structure analysis of the compounds 10 - 12 reveals the expected trigonal-bipyramidal geometry at phosphorus. The ethylenediamine ligand is found to form a chelate ring, whereby one axial and one equatorial site are bridged. The coordinative P - N bonds are very long (up to 207 pm).
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  • 224
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1357-1362 
    ISSN: 0009-2940
    Keywords: Copper complexes ; Macrocyclic ligands, N-functionalized ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: trans-N2S2-Macrocyclic Ligands with Pendant Carboxylic Groups. - Synthesis of 6,7,8,9,15,16,17,18-Octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine-8,17-diacetic Acid (H2L1); Structures of Corresponding Copper ComplexesThe macrocyclic ligand with pendant carboxylic groups 6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine-8,17-diacetic acid (H2L1) and its Ni(II) and Cu(II) complexes, [NiL1]3(H3O·ClO4)4·H2O (1) and [Cu(HL1)]ClO4·1.5 H2O (2), have been prepared. The coordination properties of H2L1 towards Ni(II) and Cu(II) in aqueous solutions are independent on the pH according to UV/Vis-spectral measurements. The structures of 2 and of [CuL2]ClO4 (3) with HL2 = 6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclodetradecine-8-acetic acid have been determined by X-ray crystallography. In 2, all six donor atoms of the ligand are coordinated, forming an octahedron. Due to their size the metal atoms are not incorporated in the ligand cavity. The ligand is folded in such a way, that the N-donor atoms are in trans, and the S-(and O-)donor atoms in cis positions. In 3, the five donor atoms form a rather regular bipyramid with the N atoms in the axial positions. The stereochemistry of the ligands in the complexes 2 and 3 is discussed.
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  • 225
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1373-1375 
    ISSN: 0009-2940
    Keywords: Samarium complexes ; Iron complexes ; Lanthanides, organo- ; Heterodimetallic complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organolanthanide(II) Chemistry: Synthesis and Structure of [Cp*Sm(μ-OC)2FeCp*]2The tetranuclear complex [Cp*Sm(μ-OC)2FeCp*]2 (3) has been prepared by reaction of Cp*2Sm(THF)2 with [Cp*Fe(CO)2]2 and structurally characterized by single-crystal X-ray diffraction.
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  • 226
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1397-1402 
    ISSN: 0009-2940
    Keywords: Cyclobutane-1,3-diones ; Cyclobutane-1,3-dithiones ; Radical anions ; Diradical dianions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4-Bis(diphenylmethylene)-1,3-cyclobutanedione (1) is transformed into its sulphur analogues 2 and 3 with Lawesson's or Davy's reagent 5a,b. An X-ray structural analysis is performed on 3. The electrochemistry of these compounds is surveyed. The products of the electrochemical reduction exhibit ESR spectra, which could not be attributed to the radical anions 1-•, 2-•, and 3-•. Extensive semiempirical AM1/Cl calculations suggest the spectra to correspond to the diradical dianions. The experimental data are discussed in terms of the theoretical results.
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  • 227
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1425-1429 
    ISSN: 0009-2940
    Keywords: Allenes ; Hetero Diels-Alder reactions ; Catalysis, heterogeneous ; Glutaraldehyde ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several cycloaddition reactions of 1-alkoxy-1,2-propadienes 1 with 1-oxa-1,3-dienes 2, catalyzed by acid-free silica gel, are described. The resulting 3,4-dihydro-3-methylene-2H-pyrans 3 are transformed into synthetically interesting glutaraldehyde derivatives 10 - 13.
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  • 228
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1347-1352 
    ISSN: 0009-2940
    Keywords: 1α4,2,4,6-Thiatriazines, preparation, structures ; 1α4,2,4,6-Thiatriazinium cations ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: FluorothiatriazinesFrom the reaction of (ClCN)2(ClSN) (1) with AgAsF6 in liquid SO2 (ClCN)2(SN)⊕ AsF⊖06 (2) is obtained in quantitative yield. With CsF 2 gives (ClCN)2(FSN) (3), which slowly dismutates at room temperature to form (ClCN)(FCN)(FSN) (4) and 1. Fluorination of 1 with SbF3 yields (FCN)2(FSN) (5). With AsF5 5 forms the salt (FCN)2(SN)⊕ AsF⊖ (6). The cation of 6 is transformed by NOCl or CsBr into the corresponding neutral derivatives (FCN)2(ClSN) (7) and (FCN)2(BrSN) (8), respectively. The gas-phase structure of 5 was determined by electron diffraction. The influence of the different exocyclic substituents on the bond properties in this ring system is explained by means of MNDO calculations.
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  • 229
    ISSN: 0009-2940
    Keywords: μ-(Ethynediyl)bis(pentacarbonylrhenium) ; Acetylide-bridged carbonyl metal clusters ; Iron carbonyl complexes ; Cobalt carbonyl complexes ; Platinum carbonyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dirhenioethyne (OC)5Re-C≡C-Re(CO)5 as Building Block for the Synthesis of Carbonyl Metal ClustersThe dimetallated ethyne (OC)5Re-C≡C-Re(CO)5 (1) reacts with (Ph3P)2Pt(η2-C2H4), Fe2(CO)9, and Co2(CO)8 to give the acetylide-bridged complexes PtRe2(μ3-η1:η1:η2-C≡C)(CO)9-(PPh3)2 (2), FeRe2(μ3-μ1:η1:η2-C≡C)(CO)13 (3), and Co2Re2-(μ4-η1:η1:η2:η2-C≡C)(CO)14 (4), resp., whose structures have been determined by X-ray diffraction. These reactions of (CO)5Re-C≡C-Re(CO)5 proceed similarly to those of the isolobal organic acetylenes, but with formation of metal-metal bonds.
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  • 230
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1403-1409 
    ISSN: 0009-2940
    Keywords: Paracyclothiophenophane ; Photodesulfurization ; Pyrolysis ; Reductive ring opening reaction ; [n] Paracyclophane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dithia[3]paracyclo[3](2,4)- and -(2,5)thiophenophanes 〈dithia-[3.3](2,4)- and -(2.5)PTP〉 (3, 7, 9) are obtained by the coupling reaction of the corresponding bis(chloromethyl)- and bis(mercaptomethyl)arenes. Desulfurization of the dithia[3.3]PTPs 3, 7, 9 by photolysis affords the thia[2.3]PTPs 15, 16, 17 and [2.2]PTPs 14, 18, 19, 20 The pyrolysis of the disulfone 12 gives the symmetrical thiophenophane 13. The dynamics of the ring inversion, the UV spectra, and the reductive ring opening with Raney-Ni (W-7) of the obtained PTPs are discussed.
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  • 231
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1481-1483 
    ISSN: 0009-2940
    Keywords: Interstellar chemistry ; Polycarbon nitride radicals ; Neutralization-reionization mass spectrometry ; Tandem mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title radicals, thought to be of prime importance in the genesis of interstellar organic molecules, are accessible in the gas phase by neutralization of the corresponding CnN+ ions (n = 2-5) using tandem mass spectrometry methods (neutralization-reionization mass spectrometry). Collision-induced dissociation reactions of mass-selected CnN+ are in keeping with the connectivity of a “carbon rod” bearing a nitrogen atom at one terminus.
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  • 232
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    Keywords: Charge-transfer complexes ; Electrical conductivity ; Tetrathiafulvalenes ; Tetracyanobenzoquinodimethane ; Dicyanobenzoquinodiimine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LIV1). - Conducting CT Complexes of Tetrathiafulvalene (TTF) with Tetracyanobenzoquinodimethane (TCNQ) and N,Ń-Dicyanobenzoquinodiimine (DCNQI) - A ComparisonX-ray structure analysis and electrical conductivity together with ESR data of the CT complex DCNQI/TTF · 2 H2O (3/2 · 2 H2O) are presented and compared with those of the wellknown TCNQ/TTF (1/2).
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  • 233
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    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
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  • 234
    ISSN: 0009-2940
    Keywords: 1,3-Diborapentafulvene ; Iron tricarbonyl complexes ; Slipped triple-decker ; Calculations, ab initio, EH ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of 1,3-Dihydro-1,3-diborapentafulvene Derivatives with Fe(CO)3 Fragments: Syntheses, Crystal and Electronic Structure of μ-(η4: η5-1,3-Dihydro-1,3-diborapentafulvene)-bis(tricarbonyliron) ComplexesReactions of the 1,3-diborapentafulvene derivatives 1a-c with (CO)3Fe(C8H14)2 lead to the violet dinuclear complexes 3a-c, which possess a slipped triple-decker structure. The X-ray structure analyses of 3b,c reveal that one Fe(CO)3 group is pentahapto-coordinated to the 1,3-diborole frame of C2B2C=C, whereas the other interacts with the Y-shaped B2C=C unit. The latter resembles the interaction of Fe(CO)3 with trimethylenemethane. An MO calculation indicates that the formation of 3 occurs by distortion of 1 · Fe(CO)3; the slippage of Fe(CO)3 from η5 to η4 bonding is followed by η5 coordination of the second Fe(CO)3 group.
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  • 235
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1525-1530 
    ISSN: 0009-2940
    Keywords: 1,3-Diphosphabenzene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, NMR spectra, and X-ray molecular structures of three (2-hetero-)1,3-diphosphabenzenes are reported which constitute an isoelectronic triade of compounds with BH2, CH, and N bridging units between the two phosphorus atoms. The remaining three carbon atoms of the rings are part of a 2-methallylic system. The 2-borataheterocycle 3 has been prepared by the reaction of CH2 = C(CH2)PPh2)2 (1) with Me2S—BH2Br to give an intermediate 2 still containing the exocyclic olefinic bond. Treatment of 2 with a base, deprotonation of one ring CH2 group, and proton migration from the other one to the olefinic CH2 group afford the 5-methyl-1λ5-phospha-3-phosphonia-2-boratabenzene 3. The PBP unit is tilted by 144.0(2)° against the planar C3P2 part of the ring. A heterocyclic precursor 4 for the carbon analog is generated from 1 and CH2I2, which on reaction with a strong base yields the diphosphabenzene 5 with a fully planar ring skeleton. For the synthesis of the aza analog 7, CH2=C(CH2Cl)2 is treated with HN(PPh2)2 to give the precursor 6, which can be deprotonatad at nitrogen and carbon with a base. In the crystals of 7, two independent molecules of very similar structure are present. The molecules show planar heterocycles.
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  • 236
    ISSN: 0009-2940
    Keywords: Gold complexes ; Palladium complexes ; Platinum complexes ; Rhodium complexes ; Iridium complexes ; 3′-Azido-3′-deoxythymidine ; 3′-Isocyano-3′-deoxythymidine ; Anti-HIV ; Antiinflammatory activity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LX.  -  Metal Complexes of 3′-Azido-3′-deoxythymidine (AZT) and 3′-Isocyano-3′-deoxythymidineMetal complexes of N-3-deprotonated 3′-azido-3′-deoxythymidine (AZT  -  H+), (AZT  -  H+)AuPR3 (R = Me, Et, Ph) (2, 3, 4), trans-(AZT  -  H+)2Pd(NH3)2 (5), [(n-Bu3P)(AZT  -  H+) M(μ-Cl)2M(AZT  -  H+)(n-Bu3P)] (M = Pd, Pt) (6, 7), trans-(Ph3P)2Pd(AZT  -  H+)2 (8), cis-(Ph3P)2Pt(AZT -  H+)(Cl) (9), and complexes of 3′-isocyano-3′-deoxythymidine (L), (Et3P)(L)- PdCl, (11), (12), (n-Bu3P)(L)PtCl2 (13), [(Ph3P)2(L)PtCl](BF4) (14), (η5-C5Me5)(L)RhCl2 (15), and (η5-C5Me5)(L)IrCl2 (16) have been prepared and characterized by IR and NMR spectra, 2 by X-ray crystallography. 2, 4, and 9 show an anti-HIV activity very similar to AZT; 2 exhibits antiinflammatory activity.
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  • 237
    ISSN: 0009-2940
    Keywords: Ferrocenes ; Cyclopentadienes, disilyl- ; Silatropic rearrangement ; Lithium cyclopentadienides ; Metallocene, trinuclear, mixed-metal ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetrahydro-4,4,8,8-tetramethyl-4,8-disila-s-indacenyl anion (LH) reacts with or without cyclopentadienyl anion (Cp-) and Fe2Cl4(THF)3 to give the mixed ferrocenes CpFe(LH) and (LH)2Fe in 50 and 63% yield, respectively. Near room temperature and in solution CpFe(LH) exists as a pair of enantiomers (syn-3a/b). According to an X-ray analysis both enantiomers are present in a single crystal. Compound 3 consists of a ferrocene linked to a cyclopentadiene by two Me2Si groups such that the acidic Cp proton points towards the iron. Temperature-dependent NMR spectra show that syn-3a and syn-3b are non-rigid molecules which are interconverted by 1,2-silatropic bond shifts (Ea = 49.2 ± 2.9 kJmol-1). Three more isomers (anti-3a, anti-3b, and the spiro derivative 3c), though present only in low concentration, are engaged in the rearrangement. (LH)2Fe is also non-rigid and exists as a pair of diastereomers (4a and 4b). The isomers of 3 and 4 undergo hydrolysis (e.g., syn-3a/3b gives [(Me2SiOSiMe2)Cp]FeCp (5) among others) and deprotonation. The latter yields CpFe(L-) (7) and (L-)2Fe (8), which are characterized by NMR spectroscopy. 7 forms crystals with [Li(TMEDA)]+ as counterion, and an X-ray analysis shows that lithium and iron are located at opposite sides of the strongly folded ligand L. The reaction of 7 with CrCl2(THF) gives the trinuclear stacked metallocene 9 in 47% yield. 9 has two unpaired electrons which are located essentially in the center of the molecule.
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  • 238
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1679-1680 
    ISSN: 0009-2940
    Keywords: Bond activation, C — H, C — C ; Transition-metal ions ; Tandem mass spectrometry ; Geminal dialkyl effect ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the internal energy content, due to the operation of a geminal dialkyl effect, the Fe+ -mediated dehydrogenation of α,α-dimethyl-substituted ketones preferably involves the more substituted alkyl chain.
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  • 239
    ISSN: 0009-2940
    Keywords: Nonclassical T1(I)-T1(I) interactions ; Thallium, fulvalene complex ; (Cyclopentadienyl)thallium complex ; 5,5′;-Pentafulvalene, 1,1′;,3,3′;-tetra-tert-butyl-dithallium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (1,1′,3,3′-Tetra-tert-butyl-5,5′-pentafulvalene)dithallium - Synthesis and Crystal Structure: a Contribution to the Discussion of Nonclassical TI(I)-TI(I) InteractionsReaction of 1,1′,3,3′-tetra-tert-butyl-5,5′-dihydropentafulvalenediyldilithium with stoichiometric amounts of thallium chloride affords the dinuclear complex (η5:(η5-tBu4C10H4)Tl2 (2). Compound 2 is air-and moisture-sensitive, and photolabile. It crystallizes in the space group P•1 and consists of two (cyclopentadienyl)thallium units which are connected by a central C-C bond and twisted against each other by 70°. The monomeric units of 2 form a two-dimensional polymer with a zick-zack chain of T1 atoms and a periphery of substituted cyclopentadienyl ligands. Rather short T1-T1 contacts of 3.760 and 3.998 Å are formed within a dimeric substructure. The geometry of the cyclopentadienyl ligands around the shortest T1-T1 bond is similar to that predicted by the theory for weak T1-T1 interactions.
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  • 240
    ISSN: 0009-2940
    Keywords: Allenes, highly strained ; Strain  -  structure correlation ; Hybridization effects, 13C, 13C coupling constants ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(tetramethylcyclopropylidene)methane (5) was prepared by treating 1-(dichloroethenylidene)-2,2,3,3-tetramethylcyclopropane (3) with tert-butyllithium in the presence of 2,3-dimethyl-2-butene. The parent allene 6 was obtained along a new route from bis(1-bromocyclopropyl) ketone (11) with low-valent titanium. Both 5 and 6 show unusually intense allene stretching bands in the IR spectra, and the signals of their central carbon atoms appear at remarkably high field in the 13C-NMR spectra. The unique structural features of 5 and 6, as evidenced by an X-ray crystal structural analysis of 5 and 1Jcc values, agree remarkably well with theoretical predictions made by semiempirical (MNDO) and ab initio (4-31G) calculations and on the basis of the simple picture offered by the hybridization model using the iterative maximum overlap (IMO) approach.
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  • 241
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1727-1731 
    ISSN: 0009-2940
    Keywords: Conformational analysis ; Benzene, donor-acceptor-substituted ; Benzene ring, distortion of ; Hydrogen bonding, intramolecular ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray crystallographic analysis of the mono-, di-, and tri-potassium salts 2b - d of trinitrophloroglucinol (2a) show their benzene rings to become considerably more distorted on successive deprotonation. A parallel increase in C - C, and a decrease in C - O and C - N bond lengths leading to a radialenetype structure is also observed. For 2b, two chemically different molecules are found in the crystal which differ in their hydrogen-bond pattern as well as in their average bond lengths and deviation of their benzene rings from planarity. AM1 calculations show that for 2b,d a multitude of structures, differing widely in the deviation of their benzene cores form planarity, can exist within a small energy range ( 〈 3 kcal/mol). The experimental and computational results are discussed in terms of a model that emphasizes “push-pull” interactions as the main cause for the distortions of the benzene rings in compounds of type 1 and 2.
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  • 242
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1747-1755 
    ISSN: 0009-2940
    Keywords: 4H-Pyrazole-4-thiones, 3,3,5,5-tetraalkyl-3,5-dihydro ; Thiiranes, 3,3-dialkyl-2-alkylidene ; 1,3-Pentadiene-3-thiol, 2,4-dimethyl ; Photolysis ; Extrusion of molecular nitrogen ; (E)/(Z) Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetraalkyl-1-pyrazolin-4-ones 5 react with hydrazine to afford the hydrazones 6 which are transformed into the thiones 7 in high yields by treatment with disulphur dichloride in the presence of triethylamine. Selective excitation of the azo chromophor of 7a with 350-nm light gives rise to the isopropylidenethiirane 8, besides molecular nitrogen, in a very clean reaction; at almost quantitative conversions, less than 2% of byproducts are observed, and about 10% of 8 have isomerized to the pentadienethiol 9. Photolysis of the stereoisomers cis- and trans-7b yields mixtures of the alkylidenethiiranes (E)-and (Z)-10 with (E)/(Z) ratios of 35:65 and 49:51. The results are interpreted in terms of diastereomeric bis-orthogonal (cis- and trans-21) and mono-orthogonal thioxyallyl diradicals (E)- and (Z)-23 which cyclize to furnish (E)- and (Z)-10. There seems to be a qualitative resemblance between the photochemical and thermal stabilities in the series of 4-substituted tetramethyl-1-pyrazolines, viz. 7a 〈 12 〈 5a, 13, similar to that suggested by Engel for 2,3-diazabicyclo[2.2.2]oct-2-ene derivatives.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1757-1775 
    ISSN: 0009-2940
    Keywords: Octabisvalene, 3-, 2,3-, and (Z)-3,7-(di)functionalized derivatives ; NMR Analysis, 13C,13C coupling constants ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalized OctabisvalenesQuadricyclanone (13) is the starting material for a five-step synthesis of 3-cyanooctabisvalene (24, 19% total yield), cyclooctatetraene for a six-step synthesis of (Z)-3,7-dicyanooctabisvalene (58, 7% total yield). By decyanation of 24, the parent octabisvalene (1) is produced. NMR data, including 13C,13C coupling constants, are presented.
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  • 244
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    Keywords: Aminocarbene complexes of iron ; N-Vinylaminocarbene complexes ; π-Allyl,σ-complexes of iron ; N-(2-Propenyl)aminocarbene complexes ; Methylenation of ketene imines by carbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses with Transition Metal Complexes, 52 1). - N-Vinylaminocarbene and N-(2-Propenyl)aminocarbene Complexes by Addition of Ketene Imines to Carbene Iron ComplexesKetene imines R(Me)C = C = NPh (2, R = Me, Et, i-Pr) form 1 : 1 adducts with the carbene iron complex (CO)4,Fe=C(OEt)Ph (1). The initial step of the reaction involves an attack of the nitrogen atom of 2 at the carbene carbon atom of 1 and a subsequent rearrangement to give N-vinylaminocarbene complexes (E/Z)-4. In a parallel process with different regiochemistry the central carbon of the CCN unit is attached to the carbene carbon to yield π-allyl,σ-complexes (E/Z)-3. Alkylation of 3a with [Et3O]BF4 leads to the formation of a cationic N-(2-propenyl)-aminocarbene complex 6a. Protonation of 4 with trifluoroacetic acid results in a ring contraction to give the four-membered metallacycles 7. X-ray data are reported for prototypes (Z)-4c and 6a.
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  • 245
    ISSN: 0009-2940
    Keywords: Conformational analysis ; “Push-pull” interaction ; Benzene ring, deformation to boat and twist-boat forms ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray analyses of three 1,3,5-tris(alkylamino)-2,4,6-trinitrobenzenes (alkyl = iPr, neopentyl, tBu; 1d - f) show their benzene rings to be highly distorted towards boat (1d iPrNH2) and twist-boat (1e,f) forms. The patterns found for intramolecular donor-acceptor interaction and hydrogen bonding depend on the conformation of the benzene core: boat structures have the “stern” amino group strongly donating to the “bow” nitro group in the para position and two stronger hydrogen bonds between the substituents on the “side” of the boat, whereas twist-boat structures have two amino groups strongly interacting with the nitro group in their common ortho position to which there are also two strong hydrogen bonds. 1d - f undergo conformational exchange on the 13C-NMR time scale at room temperature. Cooling to 220 K allows detection of all carbon signals and shows C1 symmetry to be present. AM1 calculations reproduce the distortions of 1d - f. Computations on several 2,4,6-tridonor-substituted 1,3,5-trinitrobenzenes indicate that the pronounced deviations from planarity in 1a - f originate largely from electronic effects.
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  • 246
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1739-1746 
    ISSN: 0009-2940
    Keywords: Nitrilimines ; Phosphorus heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions involving the λ3-phosphorus atom of N-[bis(diisopropylamino)phosphanyl)]-C-[(bis(diisopropylamino) -thio-phosphoranyl)nitrilimine (1) are reported. Addition of elemental sulfur or selenium to 1 leads, by a formal [1 + 4] cycloaddition, to 1,3,4,2λ5-thiadiazaphosphole 3a or 1,3,4,2λ5-selenodiazaphosphole 3b in 85 and 84% yield, respectively. Reactions of 1 with dimethyl acetylenedicarboxylate and tetracyanoethylene afford the corresponding [2 + 4] adducts 1,2,3λ5-diazaphosphinine 6 (80% yield) and 1,2,4,3λ5-triazaphosphinine 10 (80% yield). Phenyl azide reacts with 1 with loss of nitrogen to give 1,2,4,3λ5-triazaphosphole 15 (74% yield), while the reaction of 1 with α-diazo ketone 17 leads with conservation of the N2 grouping to the formation of 1,2,4,3λ5-triazaphosphole 20 (85% yield). Addition of methyl trifluoromethanesulfonate to 1 affords N-[bis(diisopropylamino)methylphosphonioyl]-C-[bis(diisopropylamino)thiophosphoranyl]nitrilimine 22. In contrast to 1, the new stable nitrilimine 22 is strongly electrophilic. [2 + 3] cycloadditions are observed with ethyl vinyl ether, styrene, methyl acrylate and phenylacetylene to furnish the corresponding pyrazolines 23 - 25 and pyrazole 26 in good yields. Water adds to 22 by a 1,3-addition process to give hydrazine 27 (88% yield). The lithium salt 30 of [bis(diisopropyl-amino)thiophosphoranyl](diazo)methane reacts with [bis(pentafluorophenyl)](chloro)phosphane to afford the corresponding diazo compound 32 (50% yield) while the reaction with (chloro)(phenyl)[2,4,6-tris(trifluoromethyl)phenyl]phosphane furnishes nitrilimine 33 in 82% yield. Only 1,3-addition reactions with water or diisopropylamine leading to hydrazine 34 (65% yield) and hydrazone 35 (54% yield) are observed on treatment with this new poorly reactive nitrilimine.
    Additional Material: 10 Ill.
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  • 247
    ISSN: 0009-2940
    Keywords: Azaoctabisvalenes ; Heterocycles, novel ; Carbonitriles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Aza- and syn-3,7-Diazaoctabisvalene. - Syntheses, X-ray Structural Analyses, Novel HeterocyclesPreparatively useful routes for 3-aza- and syn-3,7-diazaoctabisvalenes have been designed based on well available materials. Thus, 7-cyano-3-azaoctabisvalene (4) becomes available in a six- (five-) step synthesis from the valence tautomers 7-cyanotropilidene ⇄ 7-cyanonorcaradiene (7 ⇄ 8) (derived dioxides 9/10) in an overall yield of ca. 30%, syn-3,7-diazaoctabisvalene (5) in a three-step synthesis from muco-diazidotetrol 30a in ca. 25% overall yield. For 4 and 5 spectroscopic (e.g. 15N-NMR resonances, 13C,13C coupling constants) and structural details (X-ray analyses) are determined. 4 and 5 serve as starting materials for the construction of several novel heteropolycyclic skeletons (e.g. 46, 48, 50, 51, 52, 54).
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  • 248
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1805-1807 
    ISSN: 0009-2940
    Keywords: 1,3-Dithietane 1,1,3,3-tetroxides, substituted ; Nonafluorobutanesulfonates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of 1,3-Dithietane 1,1,3,3-Tetroxide (Disulfene) by NonafluorobutanesulfonatesSilyl and alkyl esters of nonafluorobutanesulfonic aicd are extremely powerful substitution reagents for disulfenes. Starting from trans-2,4-trimethylsilyldisulfene (1) and methyl nonafluorobutanesulfonate (11), 2,4-dimethyl-2,4-bis(trimethylsilyl)-1,3-dithietane 1,1,3,3-tetroxide (2) is prepared. 2 is hydrolyzed to 2,4-dimethyl-1,3-dithietane 1,1,3,3-tetroxide (3). Rapid H/D exchange reaction of 3 with D2O leads to 4. Compound 3 is deprotonated by aqueous potassium hydroxide and a potassium salt is obtained, the structure of which is most probably 5a. 2,2,4,4-Tetramethyl-1,3-dithietane 1,1,3,3-tetroxide (7) is obtained from 5 and methyl iodide, i.e. the ring system remains intact, whereas hydrolysis furnishes the ring-opened product 6.  -  Three new routes for the synthesis of methyl nonafluorobutanesulfonate (11) via the silver salt 9 or dimethyl sulfate (96% yield) or nonafluorobutanesulfonic anhydride (10) are described.
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  • 249
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1831-1835 
    ISSN: 0009-2940
    Keywords: [6]Paracyclophanes ; Dewar isomers ; Prismane isomers ; Photo valence isomerization ; Quantum yields ; Activation energy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation in the wavelength range of λ = 270 - 320 nm of 8,9-bis(N-cyclohexylcarbamoyloxymethyl)-[6]paracyclophane(1b) in dilute fluid solutions produces the 1,4-Dewar isomer 2b in a quantum yield of 2.8% while the quantum yield of the rearomatization is 19% in heptane at room temperature. A photostationary equilibrium may be attained which depends strongly on the wavelength of irradiation. At λ = 290 nm 76% of the [6]paracyclophane isomer 1b is obtained whereas at λ = 310 nm 83% of the Dewar isomer 2b is formed in ethanol. The thermal back reaction 2b → 1b follows the Arrhenius law (Ea = 95.9 ± 4.0 kJ/mol, lg A = 10.6 ± 0.4 in heptane). By irradiating 1b with λ 〈 270 nm the prismane isomer 3b is formed via the Dewar isomer 2b.
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  • 250
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1865-1866 
    ISSN: 0009-2940
    Keywords: Carbonyl carbenes ; Oxygen ylides ; Displacement, nucleophilic, intramolecular ; Carbenes ; Ylides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crown Ethers from o-Quinone Diazides and OxetaneThe carbenes 11, generated by photolysis of the di- and tetrachloro-o-quinone diazides 10, react with oxetane in a 1:3 ratio to give the 15-membered crown ethers 19. In the presence of methanol, the oxonium ions 12 are trapped with formation of 1-(aryloxy)-3-methoxypropanes (13). In the absence of additional nucleophiles, 12 reacts with oxetane until the chain length is appropriate for inverting intramolecular attack of the aryl oxide at the α-carbon atom of the oxonium ion (18 → 19).
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  • 251
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1867-1869 
    ISSN: 0009-2940
    Keywords: Carbenes, nucleophilic ; Cyclohexadienylidenes ; Pyrylium ions ; Carboxonium ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Vinylogous Oxycarbenes with MethanolThe carbenes 16 and 30 were generated in methanol/sodium methoxide by photolyses of 2-methylchromone tosylhydrazone (14) and 3,5-dimethoxy-4,4-dimethyl-2,5-cyclohexadienone tosylhydrazone (28), respectively. Neither 16 nor 30 accept methanol at the carbenic site to give products of a formal O - H insertion. Carbene 16 affords 2-methoxy-2-methyl-2H-1-benzopyran (19) by way of the benzopyrylium ion 17. The same ether was obtained from the independently prepared perchlorate of 17. Protonation of 30 was followed by demethylation of the delocalized carboxonium ion 31 to give 5-methoxy-6,6-dimethyl-2,4-cyclohexadienone (33) as the only product.
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  • 252
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1885-1885 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 253
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1885-1885 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 254
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    Keywords: (Diisoalkylamino)boradiylbenzene derivatives ; Borolo[3,2-b]borole ; 2,8-Diborabicyclo[3.2.1]octa-3,6-diene ; Borylation of benzene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twofold Borylation of Benzene Derivatives with (Diisoalkylamino)boradiyl UnitsThe reaction of subvalent boron species generated by the defluorination of difluoro(diorganylamino)borane with Na/K alloy in the presence of 1,4-disubstituted benzene derivatives leads to products which contain two (diorganylamino)boradiyl units and two remaining double bonds which are located on the substituted C atoms. Compounds 5 to 8 exhibit structures based on a 2,8-diborabicyclo[3,2,1]octa-3,6-diene skeleton while 9 shows a skeleton with a 1,3a,4,6a-tetrahydroborolo[3,2-b]borole structure. The latter structure corresponds to that of 1 obtained in the same reaction with benzene. The compounds are characterized by elemental analyses and spectroscopically [MS, NMR (1H, 11B, 13C, 15N, 19F, 29Si)]. X-ray structure analyses are presented for 1, 6, 7, 8, and 9.
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  • 255
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1923-1929 
    ISSN: 0009-2940
    Keywords: 1,3,2,4-Diphosphadisiletanes, 1,3-bis(tert-butylmercurio)-substituted ; Mercury - phosphorus bond ; 1,3-Diphospha-2,4-disilabicyclo[1.1.0]butanes ; Silicon inversion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Facile Synthesis of 1,3-Diphospha-2,4-disilabicyclo[1.1.0]butanes and Isomerization by Silicon InversionDilithiation of the PH positions of the P2Si2 cyclobutanes 2a - h with n-BuLi and treatment with tBuHgCl leads to the 1,3-bis(tert-butylmercurio) compounds 3a - h. According to NMR spectroscopy and X-ray structural analysis the tert-butylmercurio groups at phosphours occupy trans configuration. Photolysis of solutions of 3a - d and 3f, g in toluene yields the corresponding 1,3-diphospha-2,4-disilabicyclo[1.1.0]butanes 1a - d and 1f, g. Interestingly, the dimercury compound 3e (R = mesityl and tert-butoxy) is quite stable in visible light, probably due to intramolecular donor (tBuO) acceptor (Hg) stabilization. Starting from 3b, the light-induced elimination of the tBuHg groups gives the expected exo,endo-P2Si2-bicyclo[1.1.0]butane 1b only as intermediate. The final product of the latter photolysis is the CMe3/CMe3-exo,exo isomer 1b′. The formation of 1b′ from 1b is an irreversible silicon inversion process caused by unfavourable interaction of the endo substituents in 1b. In comparison, the exo,endo isomer of 1g (R = isityl and CMe3 at silicon) does not rearrange to the Me3C/Me3C-exo,exo derivative 1g′ under similar photolysis conditions or when heated at 140°C for several days. The route to 1,3-diphospha-2,4-disilabicyclo[1.1.0]butanes 1 described herein allows the synthesis of new derivatives which cannot be prepared from disilenes and white phosphorus.
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  • 256
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    Keywords: Antitumor agents ; Antiviral agents ; Acyclonucleosides ; Pyrimidines ; Acetales ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2,4-bis-O-trimethylsilyluracil (2) and 5-fluoro-2,4-bis-O-trimethylsilyluracil (3), respectively, with acetals 4a - m of various aliphatic and aromatic aldehydes in the presence of trimethylsilyl trifluoromethanesulfonate (5) at - 30°C gives the 1-(1'-alkoxyalkyl)- and 1-(1'-alkoxy-1'-phenylmethyl)-pyrimidines 6a - m and the corresponding 5-fluorouracil derivatives 7a - f in 40 - 91% yield.
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  • 257
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2041-2046 
    ISSN: 0009-2940
    Keywords: 1,3-Diradicals, energy well, singlet-triplet splitting ; 1,3-Cyclopentanediyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Cyclopentanediyls - Intermediates or Transition States?The energy well of the singlet diradicals 4a and 6 has been determined by the oxygen trapping technique to be 2.7 and 1.9 kcal/mol, respectively. From the oxygen and temperature dependence of the trapping rate of the diradical 4a activation barriers of 2.2 and 4.9 kcal/mol have been derived for the mutual interconversion of the spin isomers with the triplet being the ground state.
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  • 258
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1973-1976 
    ISSN: 0009-2940
    Keywords: 2-Phosphonioallene ligands ; Metallobis(methylene)phosphoranes ; Nickel complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of 2-Phosphonioallene ComplexesThe reaction of the chlorobis(methylene)phosphorane 1 with reactive olefin complexes of nickel and platinium affords the 2-phosphonioallene complexes 4b and 6a,b. The structure of this new class of three-electron donor ligands, involving a lowcoordinated phosphorus (V) cation, has been elucidated by NMR spectroscopy and a single-crystal X-ray study of 6a. The reaction proceeds via a metallobis(methylene)phosphorane intermediate, which could be isolated in the case of the (Et3P)2Pt complex 3a.
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  • 259
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1997-2000 
    ISSN: 0009-2940
    Keywords: Electrophilic aromatic substitution ; Sulfodestannylation ; Isocyanates, sulfonyl, aromatic ; Sulfonyl compounds ; Trialkylarylstannanes, application of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 260
    ISSN: 0009-2940
    Keywords: Charge-transfer complexes ; Conductivity ; Redox systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LVI. - Crystal Structures and Conductivities of the CT Complexes TTF/2-X-5-Me-DCNQI (X = Cl, Br, I) from Tetrathiafulvalene and 2-Halogeno-N,N′-dicyano-5-methyl-1,4-benzoquinone DiimineIn contrast to microcrystalline powders single crystals of the title complexes show low conductivities (&10; 〈 sigma-5 Scm-1). These properties are based on a peculiar mixed stack arrangement of donor and acceptor molecules within the crystal lattice (space group P21/n).
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  • 261
    ISSN: 0009-2940
    Keywords: Heterobimetallic complexes ; Tungsten complexes ; Iron complexes ; Ruthenium complexes ; Manganese complexes ; Rhenium complexes ; Diene bridges, σ,π-C6, -C7, and -C8 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal Complexes, XX. - Nucleophilic Addition of Carbonyl Metallates to Cationic Hexadienyl, Cyclohexadienyl, Cycloheptadienyl, and Cyclooctadienyl Complexes of Iron and Ruthium: Heterobimetallic Complexes with η1:η4, -C6, -C7, and -C8 Hydrocarbon BridgesThe addition of Re(CO)-5, Mn(CO)-5, and [(η5-C5H5)W(CO)3]- to the cationic dienyl complexes [(η5-dienyl)M(CO)3]+ (M = Fe, Ru; dienyl = hexadienyl, cyclohexadienyl, cycloheptadienyl, cyclooctadienyl, bicyclo[5.1.0]octadienyl) gives the heterobimetallic η1:η4-hydrocarbon-bridged complexes 1 - 4, 6, 7. In solution the initial nucleophilic adduct 2e of [(η5-cyclo-hexadienyl)Ru(CO)3]+ and [Re(CO)5]- rearranges to the complex 3, in which the Re(CO)5 group is bound to a sp2 carbon atom. By using Mn(CO)-5 also the products of electron transfer between cation and anion have been observed. The crystal structures of (OC)3Fe(μ-η4:η1-hexadiene)Re(CO)5 (1), (OC)3Ru(μ-η4:η1-cyclohexadiene)Re(CO)5(3), (OC)3Fe(η4:η4-C7H9 - C7H9)Fe(CO)3 (5), (OC)3Ru(μ-η4:η1-cyclooctadiene)Re-(CO)5 (6b), and of (OC)3Fe(η4:η1-bicyclo[5.1.0]octadiene)-Re(CO)5 (7) have been determined by X-ray diffraction.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2259-2262 
    ISSN: 0009-2940
    Keywords: Hydroborate ; triethyl ; sodium salt ; Sodium  -  arene addition compound ; Mesitylene ; Tricoordinated H atoms ; Solid-solid phase transformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystalline Sodium Triethylhydroborate  -  Formation and CharacterizationTwo equiv. of NaHBEt3 (1) and one equiv. of mesitylene form a crystalline compound, which is characterized by DSC and by a single-crystal X-ray structure analysis at 190 K as the solid phase 2.
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  • 263
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2297-2301 
    ISSN: 0009-2940
    Keywords: Aromatic substitution, electrophilic ; Azo compounds, synthesis of ; Diazonium compounds, aromatic, coupling reaction of, with trialkylarylstannanes ; Trialkylarylstannanes, application of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for the preparation of aromatic diazene derivatives 3a  -  1, 5, 7a, b, 9 under very mild conditions is described. The reaction of trialkylarylstannanes with nitro-substituted benzenediazonium tetrafluoroborates leads, by strict ipso substitution, to the corresponding diaryldiazenes in satisfactory to high yields. Due to the excellent leaving group quality of the stannyl group azo compounds may be prepared which are not accessible by normal electrophilic azo coupling. The products can be valuable precursors, obtained by reduction to the amines or other derivatizations, for consecutive aromatic compounds.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2209-2216 
    ISSN: 0009-2940
    Keywords: Tetrazatetraborocanes ; Boron-nitrogen ring compounds ; [2 + 3] Cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight-Membered BN Rings (RBNR')4 from Four-Membered BN Rings (RBNtBu)2 by an Exchange NtBu/NR'Reactions of the four-membered BN ring compounds (RBNtBu)2 (1a - e: R = Me, Et, iPr, iBu, Pr) with azides R'N3 (R' = PhCH2, Pr, iBu, Ph) and with the nitrone PhHC=N(Me)=O are studied. The five-membered ring [=(Me)B=N(tBu)-N=N-(PhCH2)N=] (2a) is formed from the four-membered ring 1a and PhCH2N3 in the ratio 1:2. An exchange of NtBu for NR' with elimination of tBuN3 is observed, however, in the reaction of the ring compounds 1b -d with R'N3. Instead of four-membered BN rings, the six-membered BN ring (RBNR')3 (3a: R/R' = Et/PhCH2) and the eight-membered BN rings (RBNR')4 (4a -h: R/R' = iPr/PhCH2, iBu/PhCH2, iPr/Pr, iBu/Pr, iPr/iBu, iBu/iBu, Et/Ph, iBu/Ph) are formed, respectively. The NMR spectra reveal diastereotopic methylene protons (Et, Pr, iBu, PhCH2) and methyl groups (iPr, iBu) and thus elucidate the tub-like structure of the eight-membered rings. 3a and 4a crystallize in the space group P2,/c. The reaction of the four-membered rings 1c - e with the nitrone gives five-membered rings [=(R)B=N(tBu)=B(R)=N(Me) - O=] (5c - e). Both of the reactions of the four-membered rings with azides and with the nitrone can be rationalized in terms of a similar sequence of reaction steps.
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  • 265
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2245-2248 
    ISSN: 0009-2940
    Keywords: Half-sandwich complexes ; Iridium complexes ; cyclo-Sulfido ligands ; cyclo-Selenido ligands ; Iridacycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cp*Ir(PMe3)Cl2 (1) reacts with chalcogenide ligand sources such as (NH4)Sx (x ≍ 10), (NEt4)2Se6, and H2Se to yield the half-sandwich complexes Cp*Ir(PMe3)(Sn) [n = 4 (2a), 6 (4a)] and Cp*Ir(PMe3)(Sen) [n = 2 (5b), 4 (2b)]. Desulfurization of 4a by PPh3 leads to Cp*Ir(PMe3)(S5) (3a), while both 4a and 3a react with excess P(nBu)3 to give 2a. The geometries of the cyclo-oligochalcogenide ligands in 4a and 2b have been determined by X-ray crystallography.
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  • 266
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2255-2258 
    ISSN: 0009-2940
    Keywords: Boranes, amino-vinyl ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: η2- and η4-[(Dimethylamino)vinylborane]iron Carbonyl Complexes1)Amino-vinylboranes can act as η2 (via the C = C bond) and as η4 ligands (via the C = C and B = N group) in iron carbonyl complexes. From bromo(dimethylamino)vinylborane and (dime-thylamino)methylvinylborane and Fe2(CO)9 [η2-bromo(dimethylamino)vinylborane] tetracarbonyliron (1) and tetracarbonyl[η2-(dimethylamino)methylvinylborane]iron (2), respectively, are formed in the absence of light. The η2 coordination via the C = C group in 1 is proved by an X-ray structure analysis. The C2BN frame is trans-arranged. By the action of light, 1 and 2 are transferred into the very unstable tetrahapto complexes [η4-bromo(dimethylamino)vinylborane]tricarbonyliron (3) and tricarbonyl[η4-(dimethylamino)methylvinylborane]- iron (4), which can only be investigated in solution. By using tert-butyl(dimethylamino)vinylborane the reaction leads, even in the absence of light, directly to [η4-tert-butyl(dimethylamino)vinylborane)tricarbonyliron (5), a compound likewise easily unstable. The transition of the η2 into the η4 complexes can be followed IR- and 11B-NMR-spectroscopically.
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  • 267
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2303-2306 
    ISSN: 0009-2940
    Keywords: Electrochemistry ; 1-Nitroalkenes, reduction of ; Oximes ; Amines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Nitroalkenes are reduced in high yields at -0.3 to -0.5 V (vs. SCE) at a mercury or graphite cathode to oximes. At higher cathodic reduction potentials (- 1.1 V) primary amines are selectively obtained in fair yields. Nitroalkadienes are selectively reduced at the double bond conjugated with the nitro group to either the oxime or amine.
    Additional Material: 4 Tab.
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  • 268
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2315-2321 
    ISSN: 0009-2940
    Keywords: Tetraethylphthalocyanine, metal complexes of ; Isocyanide complexes, bridged ; Porphyrines ; Semiconductors, organic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Soluble (Tetraethylphthalocyaninato)iron(II) and -cobalt(II) CompoundsThe (tetraethylphthalocyaninato)iron and -cobalt compounds Et4PcFe (9), Et4PcCo (8), and Et4PcH2 (7) have been synthesized starting from 3,4-dibromoacetophenone (1) via the corresponding dinitrile 5 or isoindolenine 6, respectively. Et4PcFe (9) reacts with tBuNC, p-diisocyanobenzene (dib), and me4dib to form the bisaxially coordinated compound Et4PcFe(tBuNc)2 (10) and the oligomers [Et4PcFe(dib)]n (11) and [Et4PcFe- (me4dib)]n (12). All of the synthesized compounds, except the oligomers with a chain length of more than 8 - 14 units, are soluble in organic solvents such as chloroform or toluene. The new compounds were characterized by 1H-, 13C-NMR, 13C-CP/NMR, UV/Vis, and IR spectra. In addition the redox properties of Et4PcCo (8) were studied by cyclic voltammetry and spectroelectrochemical methods. The Mößbauer spectra of the (phthalocyaninato)iron compounds 9, 11, and 12 demonstrate the bridged structure of [Et4PcFe(L)]n (L = dib, me4dib) (11, 12). The powder conductivity of [Et4PcFe(dib)]n (11) (σRT = 5·10-6 S/cm) is ca. 106 times higher than that of Et4PcFe (9) (σRT = 9·10-12 S/cm). After doping with iodine the oligomers 11 and 12 show an increase in conductivity of 105 and 104, respectively (σRT ≍ 10-2 S/cm for [Et4PcFe(dib)I0.85]n).
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  • 269
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2357-2359 
    ISSN: 0009-2940
    Keywords: Heptasulfanes, cyclic ; Pentasulfane, linear ; Polysulfanes, organic, HPLC of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Titanocene pentasulfide, Cp2TiS5 (1) reacts with Ph3CCl (4), C2H4(SCl)2 (6), and CH3C6H3(SCl)2 (9) to give the corresponding polysulfanes (Ph3C)5 (5), C2H4S7 (7), and CH3C6H3S7 (8) which have been characterized by NMR, mass, and Raman spectroscopy. By interconversion reactions the mentioned polysulfanes yield homologous molecules with up to 11 sulfur atoms which have been separated by reversed-phase HPLC. Linear relationships between the capacity factor and the number of sulfur atoms in the molecule have been derived for each series, and retention indices have been calculated.
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  • 270
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2373-2375 
    ISSN: 0009-2940
    Keywords: Cycloaddition ; Perchlorocyclopentadiene ; Vinyl halides ; Haloethenes ; Vinyl cations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Stereochemistry of the Reaction between Vinyl Halides and Perchlorocyclopentadiene: Cycloaddition via Vinyl CationsIn the presence of aluminium chloride vinyl halides react with perchlorocyclopentadiene to yield stereoselectively bicyclic compounds (e.g. 2a), the structure of which is determined in two cases (2a, b) by X-ray analysis. Vinyl cations are proposed as intermediates.
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  • 271
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2401-2404 
    ISSN: 0009-2940
    Keywords: Niobium complexes ; Tantalum complexes ; Siloxy group ; Silylamide ; Silylimide ; NMR, 17O ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multiple Bonds Between Main-Group Elements and Transition Metals, XCVI. - Niobium and Tantalum Complexes Having Imido LigandsThe new niobium and tantalum complexes 2b and 2c of formula M[N(SiMe3)2]2(NSiMe3)(OSiMe3) (M = Nb, b; Ta, c) are accessible by the reaction of the oxychlorides MOCl3 with the lithium amide LiN[Si(CH3)3]2 in 36 and 27% isolated yield, respectively.
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  • 272
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2411-2416 
    ISSN: 0009-2940
    Keywords: Sulfur imides, N-(fluoroformyl)-, preparation of, reactions with AsF5 ; Isocyanatosulfonium salts, preparation and structures of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isocyanatosulfonium SaltsRR'SF2 reacts with Me3SiNCO to give the corresponding N-(fluoroformyl)sulfur imides FC(O)NSRR' [R = NMe2, R' = F (7); R' = CF3 (9)]. From these AsF5 abstracts F- with formation of isocyanatosulfonium salts ONC - SRR' + AsF-6 [R = F, R' = CF3 (6); R = NMe2, R' = F (8); R = NMe2, R' = CF3 (10)]. The spectroscopic properties of the fluoroformyl derivatives and of the isocyanato salts are discussed. The structures of 8 and 10 are determined by X-ray analyses.
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  • 273
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    Keywords: Fischer carbene complexes, anionic ; Carbene, methoxy(pentacarbonylrheniopropyl) ; Chromium complexes ; Molybdenum complexes ; Tungsten complexes ; Rhenium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal Complexes, XXII1). - Addition of Anionic Fischer Carbene Complexes to Coordinated Unsaturated Hydrocarbons with C - C CouplingThe addition of [(OC)5MC(OMe)CH2]- (M = Cr,W) to the cationic complexes [(OC)5Re(C2H4)]+ and [(OC)3M' (λ7-C7H7)]+ (M' = Cr, Mo) affords the bimetallic hydrocarbon-bridged complexes (OC)5M = C(OMe)CH2CH2CH2Re(CO)5 (1) and (OC)5M = C(OMe)CH2C7H7 - λ6 - M'(CO)3 (2), respectively. The structures of 1a and 2d have been determined by X-ray diffraction.
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  • 274
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2453-2456 
    ISSN: 0009-2940
    Keywords: Arsolyl anion ; Heteroaromatics ; Gallium compounds ; Arsoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The permethylated arsolyl anion C4Me4AsLi(TMEDA) (5) has been prepared; its crystal structure (determined by X-ray diffraction) revealed an aromatic heterocycle comparable to the homologous pyrrolyl and phospholyl anions.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2475-2480 
    ISSN: 0009-2940
    Keywords: Ethylenes, 1,1-diactivate ; Michael acceptors ; 1-Oxa-1,3-butadienes ; Hetero Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title class of 1,1-diactivated ethylenes has been prepared in two steps from aldehydes and t-butyl acrylate by (i) DABCO-catalyzed coupling to give t-butyl 2-(hydroxyalkyl)-2-propenoates 11 and (ii) low-temperature Jones oxidation, followed by swift work up at low temperature. The resulting t-butyl 2-methylene-3-oxoalkanoates 12 are stabilized by sterically demanding and also by aromatic groups R. For primary unhindered alkyl groups, stability is low. The compounds enter into Michael reactions, hetero Diels-Alder additions with enol ethers, and self-dimerization.
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  • 276
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    Keywords: Oxanorbornadiene → oxepine isomerization, limitations ; [6 + 4] Tropone dimerization ; Diene enone [4 + 2] photocycloaddition, intramolecular ; Oxaquadricyclanes, X-ray structure, thermolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Transformations, 761). - Studies in the Area of the Oxanorbornadiene → Oxepine Isomerization. An Intramolecular Diene/Enone [4 + 2] PhotocycloadditionAt room temperature, the “tropone-annulated” oxanorborna diene 2b dimerizes regio- and stereospecifically to give a [6 + 4] adduct (5). Direct photoexcitation of this adduct induces intramolecular diene/enone [4 + 2] addition to 16 followed by a [2 + 2] cycloaddition to provide the dodecacycle 17. An X- ray crystal structure analysis of 17 documents the influence of the heteroatom and of the quasi-bisected ester functions on the length of the three types of oxaquadricyclane - three-membered ring bonds. Direct and sensitized excitation of 2b, c produces polymers; yet, after changing the troponoid chromophor (9, 10) oxaquadricyclane formation takes place (13, 14). In the thermolysis of the annulated oxaquadricyclanes (13, 14) the different cyclopropane C - C bonds are cleaved at a comparable rate.
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  • 277
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    Keywords: 1-Thia-3-azoniabutatriene salts ; 2-Azoniaallene salts ; 1,3-Dipolar cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Thia-3-azoniabutatriene salts 1 react with alcohols, carbonyl compounds, diazo alkanes, nitrile oxides, nitrones, enamines, and 1,3-butadienes in all cases at the C=S double bond to yield new types of 2-azoniaallene salts (3, 9a, b, 13a, b, 18, 22) and other imines (2, 20). An X-ray diffraction analysis for 9b, the reaction product of 1b with 9-diazofluorene, confirms the proposed constitution.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2523-2529 
    ISSN: 0009-2940
    Keywords: Cyclohexane ; Liquid crystals ; Oxygen effect ; Scyllitol ; Stereochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2,3,4,5,6-Hexa(eq)alkylcyclohexane Model Compounds for Structure-Property Comparisons of Saturated Discotic Liquid CrystalsThe new hydrocarbon (1α, 2β, 3α, 4β, 5α, 6β)-hexahexylcyclohexane (19) and a number of new and differently functionalized scyllo-hexaalkylcyclohexane derivatives (16a, b, 18a - c) with identical stereochemistry were synthesized stereospecifically starting from simple chemical materials. In comparison to the known scyllitol hexaester 1 and the hexaether 2 none of the novel compounds 16, 18, and 19 were thermomesomorphic. This extreme difference in the thermotropic liquid-crystalline behaviour of the hexa(eq)hydroxycyclohexane (scyllitol) derivatives 1 and 2 on the one hand and of our varied hexa(eq)alkylcyclohexans 16, 18, and 19 on the other obviously is a function of the presence and the position of the element oxygen within the side chains of these symmetric star-/disc-shaped compounds. Details concerning this oxygen effect are discussed briefly.
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  • 279
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    Keywords: Triarylamines ; Cation radicals ; Electrochemistry ; Redox catalysts ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 21 triarylamines (1n - 1z, 1za, 1zb) and triarylamine analogs (2a, 2b, 3a, 3b, 4a, 4b) with substituents in at least all three p positions and some of their cation-radical hexachloroantimonates have been synthesized. The electrochemical behavior has been studied by cyclic voltammetry. Most of the compounds show chemically and electrochemically reversible first oxidation waves in the formation of the cation radicals. With the exception of 4a and 4b, the second wave for the formation of the dication is chemically irreversible. The UV spectra of the triarylamine cation radicals have been obtained in the presence of a slight excess of SbCl5. A good Hammett correlation between the first anodic potential of only p-substituted triarylamines and the σ/σ values has been established. Some redox-catalytic properties of triarylamine cation radicals are described.
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  • 280
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    Keywords: Oxaquadricyclanes ; Donor-acceptor cyclopropanes ; Calculations, AM1, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Medium and Large Rings, XXX1). - Regioselective Thermolysis of Oligomethylene Oxaquadricyclanedicar-boxylic Esters to 3,6-Alkanooxepinedicarboxylic Esters - X-ray Structural Analyses and Semiempirical CalculationsX-ray structural analyses and semiempirical calculations for the oxaquadricyclanes 1 - 3 are discussed. The regioselectivity observed for the thermolyses of 1 - 3 (exclusive formation of 3,6-alkanooxepines 6) is in line with the assumption that preferential cleavage of the long C - C bonds between the donor and acceptor substituents of the cyclopropane rings determines the reaction course.
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  • 281
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    Keywords: Homopyrroles, mono- and bicyclic ; [3 + 2] Cycloadditions of N-vinylaminocarbene iron complexes to alkynes ; 5-Aza-1-ferra-1,3,6-trienes ; Intramolecular cyclopropanation, metal-induced ; 2H-Pyrrolium tricarbonyl iron complexes ; Pyridine, 1,2-dihydro-, tricarbonyl iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 561). - Homopyrroles and Dihydropyridines from N-Vinylamino-carbene Iron Complexes and Alkynes by Cyclisation of Intermediate 5-Aza-1-metalla-1,3,6-trienes2,3-Homopyrroles 5 and dihydropyridines 7, 8 are obtained by the light-induced addition of alkynes 4a - d (RC = CR1; R, R1 = H, CH3, C6H5, CO2CH3) to the N-vinylaminocarbene iron complex (= 3-aza-1-ferra-1,4-diene) 3. The formation of the N-heterocycles 5 and 7 as well as that of the pyrrolium carbonylferrates 6 can be explained by assuming the chelated 5-aza-1-ferra-1,3,6-trienes A to be key intermediates in this reaction. Stereochemical considerations lead to the conclusion that the ring expansion of the 4 1/2-membered ring of 3 to the 6 1/2-membered ring of A occurs without prior ≡ decomplexation by the insertion of a C = C unit into the M = C bond. NMR measurements and MNDO calculations suggest that the bicyclic homopyrroles 5 are in equilibrium with the novel monocyclic homopyrrole species 9. The structure of 6c has been established by X-ray diffraction analysis.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2609-2612 
    ISSN: 0009-2940
    Keywords: Matrix isolation ; Elimination of HCl, photochemically ; Flash pyrolysis ; Calculations, ab initio ; Photochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: HCl Elimination from Ethanesulfenyl Chloride and Chlorodimethyl SulfideThioacetaldehyde (5) is prepared by matrix photolysis of ethanesulfenyl chloride (3) or thiirane (4) and by flash pyrolysis of allyl ethyl sulfide (6). Matrix irradiation of 3 or 5 with 222-nm light results in a dehydrogenation, and a mixture of thiirene (7), ethynethiol (8), and thioketene (9) is formed. Flash pyrolysis of chlorodimethyl sulfide (1) yields ethenethiol (11) together with thiirane (4), whereas ethanesulfenyl chloride (2) gives ethene under the same conditions. The identification of thioacetaldehyde (5) is based on the comparison between the experimental and calculated IR spectra.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2633-2635 
    ISSN: 0009-2940
    Keywords: Allenes, sterically shielded ; synthesis of ; Organocuprates ; 1,4-Addition ; 1,6-Addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the sterically shielded allenes 2 and 5 by 1,6-and 1,4-addition of organocuprates to acceptor-substituted enynes and diynes, respectively, is described. Treatment of the di-tert-butyl-substituted allenes 2 with aqueous base does not cause double bond isomerization; whereas ester 2a is converted into the corresponding β-allenic acid, ketone 2b yields the 2H-pyran 6.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2637-2639 
    ISSN: 0009-2940
    Keywords: NMR, 13C, solid-state ; Calixarenes ; Conformations ; Guest-host chemistry ; Macrocyclic compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentiality of 13C (CPMAS) NMR as a conformational probe for the oligomeric macrocycles p-(tert-butyl)calix-[n]arenes (n = 4, 6, 8) and their alkoxy/acetoxy derivatives in the solid state is explored.
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  • 285
    ISSN: 0009-2940
    Keywords: Metallacyclic systems ; Vanadium ; Molybdenum ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses and Structures of Cyclic and Acyclic Compounds Containing Vanadium(V) and Molybdenum(VI)The reaction of (C2F5)2P(Cl)=NSiMe3 (2) with Cl3V=NSiMe3 in CH2Cl2 yields the eight-membered ring [(C2F5)2PN2VCl2]2 (3). (CF3)2P(Cl)=NSiMe3 (1) reacts with VOCl3 to form the eight-membered ring [(CF3)2PN]3NVCl2 (4). A six-membered ring [Ph2PN]2NVCl2 (5) can be isolated from the reaction of Ph2P(Cl)=NSiMe3 with VOCl3. 1 reacts quantitatively with MoO2Cl2 and MoOCl4 to form [MoOCl3-O-P(CF3)2=N-SiMe3]4 (6) and (CF3)2P(Cl)=N-MoOCl3 (7), respectively. The molecular structures of 3, 5, and 6 have been determined by X-ray diffraction.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2677-2684 
    ISSN: 0009-2940
    Keywords: Phosphaalkenes, C-halo, C-metal ; “Phospha-isonitrile” ; Phosphinylidenemethylene ; Phosphaalkyne, E/Z isomers ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C-Halophosphaalkenes (1, 2) were prepared in high yield by a one-pot synthesis from HCX3 or CI4 and Mes* PCl2 (Mes* = supermesityl = 2,4,6-tri-tert-butylphenyl). The C-iodophosphaalkenes Mes* P = Cl2 (1 C) and Mes*P = CHI (2c) undergo halogen-metal exchange with n-BuLi at low temperatures. The resulting carbenoids Mes*P = CILi (11 c) and Mes*P = CHLi (6) reacted with ClMMe3 (M = Si, Ge, Sn) to give Mes*P=CIMMe3 [(Z)-13: M = Ge; (Z)-14: M = Sn] or Mes*P = CHMMe3 (8-10), respectively. Further reaction of (Z)-13 and (Z)-14 with nBuLi and ClMMe3 gave Mes*P=C(MMe3 (18: M=Ge; 19: M = Sn). The carbenoid (Z)-11 c decomposed at -85°C; instead of the expected “phosphaisonitrile” Mes*P = C : (21), only Mes*C≡P (15) was obtained which lends experimental support to the theoretically predicted instability of 21.
    Additional Material: 2 Tab.
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  • 287
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2697-2704 
    ISSN: 0009-2940
    Keywords: Clusters, trinuclear and tetranuclear ; Iron clusters ; Ruthenium clusters ; Azoalkane and nitrene bridging ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Azoalkane- und Nitrene-Bridged Carbonyl Metal Clusters of Iron and RutheniumBy using cluster buildup reactions, the new azoalkane-bridged clusters Ru3(CO)9(RN=NR) (3a, R=Me, 3b, R=Et), Fe2Ru(CO)9(EtN=NEt) (4), Ru4(CO)12(RN=NR) (5a, R=Me, 5b, R=Et), and FeRu3(CO)12(EtN=NEt) (6) were obtained. Upon attempts to prepare further such compounds, the N-N bond was cleaved resulting in nitrene-bridged clusters including the new compound Fe4(CO)11(μ4-NEt)2 (9). Cluster buildup starting from Ru3(CO)9(μ3-NPh)2 resulted in Ru4(CO)11(μ4-NPh)2 (10) and FeRu3(CO)11(μ4-NPh)2 (11). The crystal structures of 5b and 9 as well as some reactions of the nitrene-bridged clusters are described.
    Additional Material: 8 Tab.
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  • 288
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2725-2729 
    ISSN: 0009-2940
    Keywords: Gold complexes ; Selenium ligands ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Triphenylphosphine)(selenourea)gold(I) chloride [Ph3PAuSeC- (NH2)2]+ Cl- (1) and the corresponding dppm derivative dppm[AuSeC(NH2)2]22+ 2l- (2) are prepared from SeC- (NH2)2 and the appropriate chloro(phosphine)gold(I) complex. The reaction between 1 and aqueous Na2CO3 leads to the neutral complex μ-selenido{bis[(triphenylphosphine)gold(I)]} (Ph3PAu)2Se (3). An analogous reaction with 2 leads to a dark red oil, which has not yet been characterized. The reaction between 3, Ph3PAuCl, and AgSbF6 leads to the ionic complex [(Ph3PAu)3Se]+SbF6- (4) in good yield. X-ray structure analyses of 1,2, and 3 confirm the expected linear geometry at the gold atom and reveal short intramolecular Au - Au contacts for 2 and 3. Short nonbonding distances between the nitrogen atoms of the amino groups and the chloride ions in the crystal structures of 1 and 2 probably indicate hydrogen bonds.
    Additional Material: 4 Tab.
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  • 289
    ISSN: 0009-2940
    Keywords: L-α-Aspartyl-L-phenylalanine, cyclisation of ; Dipeptides, cyclic ; Metal complexation by cyclic dipeptides ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ester cleavage of aspartame (L-α-aspartyl-L-phenylalanine methyl ester, 1) by equimolar quantities of NaOH is accompanied by intramolecular cyclisation to sodium 3-benzyl-6-(carboxylatomethyl)-2,5-dioxopiperazine (2). The solid-state structure of the crystalline tetrahydrate has been determined by single-crystal X-ray diffraction analysis. The cations are arranged in strings, and each sodium atom is in a distorted octahedral environment of six oxygen atoms, including a β-carboxylato (O1) and an oxo function (O4) of two different dioxopiperazines and four water molecules. No nitrogen coordination is observed. Through the ligand bridging (O1, O4) of the metals and a set of hydrogen bonds involving the amide and carboxylate groups and all water molecules a three-dimensional network is established.
    Additional Material: 2 Ill.
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  • 290
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2747-2748 
    ISSN: 0009-2940
    Keywords: η2-Thiocarbene complex, amphiphilic ; Molybdenum, carbene complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbonyl(η5-cyclopentadienyl)(trimethylphosphane)[η2-(methylthio)phenylcarbene]molybdenum Tetrafluoroborate - an Amphiphilic Carbene ComplexThe title complex 1 adds the electrophile SMe+ as well as the nucleophilic PMe3 at the carbene carbon to form the complexes 2 and 3, respectively.
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  • 291
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 529-535 
    ISSN: 0009-2940
    Keywords: Perylene dyes ; Hydrocarbons polycyclic ; Fluorescent dyes ; Fluorescent labelling ; Fluorescent tracer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Nonsymmetrically Substituted Perylene Fluorescent DyesA general method for the preparation of perylene-3,4:9,10-tetracarboxdiimides 1 with two different substituents at the nitrogen atoms is described: The easily prepared symmetrical tetracarboxdiimides 1 (R1=R2) are transformed into carboxdiimide anhydrides 2 and condensed with primary amines to the corresponding tetracarboxdiimides 1 (R1 ≢ R2). Applications as fluorescent tracers in biochemistry and polymer chemistry are discussed.
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  • 292
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 563-569 
    ISSN: 0009-2940
    Keywords: Allylboration reaction ; Stereoselectivity in electrophilic attack on C—C double bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the addition of α-substituted allylboronates 4 (X=H, Cl, Br, OCH3, SCH3] to aldehydes have been measured. The results have been used to differentiate between different models that have been advanced to account for the high proportion of (Z)-configurated homoallyl alcohols 5 formed in allylboration reactions. Attempts have been made in this context to detect ate-complex formation between benzylboronates and aldehydes.
    Additional Material: 3 Ill.
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  • 293
    ISSN: 0009-2940
    Keywords: Hetero Diels-Alder reaction ; Knoevenagel reaction ; D-Homoestrones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tandem Knoevenagel hetero Diels-Alder reaction of the secoestrone derivative 8 with dimethylbarbituric acid (9a). Meldrum's acid (9b), and the pyrazolones 13a-c stereoselectively affords the D-homoestrone derivatives 11a, 12, and 14a-c, respectively, with the 16α,17aα configuration in excellent yield. In the reaction of 8 with 9a, b only one diastereomer can be detected, whereas in the reaction of 8 with 13a-c a small amount of the isomeric adducts 15a-c has also been found.
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  • 294
    ISSN: 0009-2940
    Keywords: syn-Azo azides ; Triaziridines, cis,cis-trialkyl- ; Stabilization, kinetic ; Ring expansion ; Calculations, MMX ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The as yet unknown route to triaziridines by the addition of nitrenes to the π side of the N=N bond is achieved intramolecularly by the photolysis (thermolysis) of syn-azo azide substrates with high proximity; the yields reflect the sterical (and possibly inductive) influences of the skeleton. The product composition is rather independent of the exciting light; intramolecular azo → azide energy transfer is assumed. The kinetic skeleton stabilization of the triaziridines permits the synthesis of 17 (18) by the thermolysis of 7 (8) at 200°C with the product composition deviating only marginally from that of the photolysis. Attempts towards enlargement of the triaziridines to N3X rings (X=CHR, O, NR) lead exclusively to products of intramolecular fragmentation.
    Additional Material: 3 Tab.
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  • 295
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 677-681 
    ISSN: 0009-2940
    Keywords: Bromozirconate(IV) ; Di-μ-bromooctabromodizirconate(2-) ; Tri-μ-Bromohexabromodizirconate(-) ; Tetratellurium(2+) ; Tribromotellurium(+) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ZrBr4 reacts with Te2Br in a sealed evacuated ampoule at 210°C in quantitative yield to afford (Te24⊕)(Zr2Br210⊖) as blueblack, moisture-sensitive crystals. The crystal-structure determination shows, that (Te4)(Zr2Br10) consists of planar, nearly square Te24⊕ and Zr2Br210⊖ ions, that form edge-sharing double octahedra. Both ions possess crystallographic 2/m (C2h) symmetry. At temperatures above 250°C (Te4)(Zr2Br10) decomposes with cleavage of Te -Te bonds into (TeBr3⊕)(Zr2Br9⊖), which forms yellow, hygroscopic crystals. (TeBr3)(Zr2Br9) can also be obtained by the reaction of two equivalents of ZrBr4 with TeBr4 at 260°C. The crystal structure is built of Zr2Br9⊖ ions, that form face-sharing double octahedra, and of pyramidal TeBr3⊕ ions. Each TeBr3⊕ ion exhibits three Te - Br contacts to two different Zr2Br9⊖ ions, resulting in a strongly deformed octahedral coordination for the Te atom. The Zr2Br9 double octahedra and the TeCl6 octahedra are connected by common edges and corners to infinite chains.
    Additional Material: 5 Ill.
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  • 296
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 713-717 
    ISSN: 0009-2940
    Keywords: Transition metal complexes with 1-selenoglucose ; Glucose as ligand ; Selenoglucose ; Carbohydrates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LVII. - 1-Selenoglucose as Ligand in Metal ComplexesReactions of the in situ-prepared anion of acetylated 1-selenoglucose with chloro complexes give the compounds R'3 PAuSeR (R'=Me, El, Ph), cis;-(Ph3P)2Pt(SeR)2 and (η5C5H5)2Ti(SeR)2 (SeR=2,3,4,6-tetra-O-acetyl-1-seleno-β-D-glucopyranosato-Se). The complexes (η5-C5H5)(OC)2FeSeR and (OC)3M(μ-SeR)2M(CO)3 (M=Fe, Ru) are prepared by the reaction of the diselenide RSeSeR with the dinuclear compound [η5-C5H5Fe(CO)2]2 and M3(CO)12 (M=Fe, Ru), respectively.
    Additional Material: 4 Tab.
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  • 297
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 743-751 
    ISSN: 0009-2940
    Keywords: Stannyl complexes ; Hydride complexes ; Three-center bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Stannyl Complexes, 3. - Metal, Hydrogen, Tin Three-Center Bonding in Group VI Hydrido Stannyl ComplexesThe hydrido stannyl complex (π-1,3,5-Me3C6H3)(CO)2Cr(H)-SnPh3 (1) is prepared by photochemical reaction of (π-1,3,5-Me3C6H3)(CO)3Cr with HSnPh3. The 119SnHCr coupling constant (327.6 Hz) and an X-ray structure analysis [Sn - H 202(4), Cr - H 159(4), Cr - Sn 270.16(6) pm] show that the Sn - H bond is coordinated in an η2 fashion. The complexes (CO)4(R3P)-W(H)SnPh3 (R3P=Ph3P, MePh2P) (2) and (CO)3(dppe)M(H)-SnR3 (M=Cr, SnR3=SnPh3; M=Mo, SnR3=SnMe3, SnPh3; M=W, SnR3=SnMe3, SnPh2Me, SnPh3) (4 - 6) are obtained either by thermal reaction of (CO)4(R3P)W(THF) or (CO)3(dppe)ML (L=THF, acetone) with HSiR3, or by photochemical reaction of (CO)4(dppe)M with HSnPh3. Reaction of (CO)4(Ph3P)W(THF) with HSnMe3 yields (CO)4(Ph3P)W(Sn-Me3)2 (3). The Sn,M,H coupling constants in the complexes 2 and (CO)3(dppe)M(H)SnR3 (M=Cr, Mo) are in the range of 250 - 315 Hz and therefore these complexes seem to contain an η2-coordinated stannane. Contrary to this, the SnWH coupling constants in (CO)3(dppe)W(H)SnR3 are considerably lower (70 - 90 Hz), suggesting complete oxidative addition of the H - Sn bond. The complexes (CO)3(dppe)M(H)SnPh3 decompose in benzene solution at room temperature to give, inter alia, hexaphenyldistannane. Ph6Sn2 · 2 C6H6 crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ R\bar 3 $\end{document} (Z=1); in the crystal lattice the benzene molecules are perpendicular to the three-fold axis of symmetry of the distannane molecule.
    Additional Material: 2 Ill.
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  • 298
    ISSN: 0009-2940
    Keywords: Squaric acid ; ester amides of ; diamides of ; Coupling reagents ; Biopolymers ; Anticancer agents ; Conjugates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of squaric acid diethyl ester (1) with a slight excess of a primary or secondary amine 2 in ethanol, dichloromethane or aqueous buffer (pH 7) at 20°C for 0.3-12 h gives the squaric acid amide esters 3 in mostly excellent yields. Treatment of 3 with amines 2 or 4 in organic solvents in the presence of triethylamine or in aqueous buffer (pH 9) leads to the corresponding symmetrical and unsymmetrical squaric acid diamides 5, respectively. The reaction can be followed by UV spectroscopy.
    Additional Material: 2 Tab.
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  • 299
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1259-1264 
    ISSN: 0009-2940
    Keywords: Carbenoids ; Configurational stability ; Organolithium compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbenoids 2 undergo at -110°C a bromine/lithium exchange reaction with 1,1-dibromo alkanes. This leads to partial equilibration of the carbenoids 2 during their generation from the 1,1-dibromo compound 1. In the absence of the precursor 1, the carbenoids 2 have been found to be configurationally stable at -110°C.
    Additional Material: 1 Ill.
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  • 300
    ISSN: 0009-2940
    Keywords: Tetrahedranes, organometallic ; 1,3-Diphospha-2-propanone derivatives ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Diphosphenes, XX1). - Synthesis and Properties of the Tetrahedrane [(η5-C5Me5)(CO)2-FeP-PtBu]Fe2(CO)6 and the Metalated 1,3-Diphospha-2-propanones [(η5-C5Me5)(CO)2Fe-PC(O)-PR]Fe2(CO)6 [R = tBu, 2,4,6-(CF3)3C6H2]The reaction of [η5-C5Me5)(CO)2FeP(SiMe3)2 (1) with tBuPCl2 (2a) affords the metalated cyclotetraphosphane [(η5-C5Me5)-(CO)2FeP-PtBu]2 (4a) besides the metal-substituted cyclotriphosphane (η5-C5Me5(CO)2Fe-P[PtBu]2 (5a) and the diphosphane (η5-C5Me5)(CO)2FeP(SiMe3)P(Cl)tBu (3a), which are detected in the reaction mixture by 31P-NMR spectroscopy. Treatment of 4a with excess of Fe2(CO)9 leads to the tetrahedrane [(η5-C5Me5)(CO)2FeP-PtBu]Fe2(CO)6 (6a) and the 1,3-diphospha-2-propanone derivative [(η5-C5Me5)(CO)2FePC(O)-P-tBu]Fe2(CO)6 (7a). Similarily, an analogous complex 7c is obtained from the reaction of in situ prepared (η5-C5Me5)-(CO)2FeP=P-C6H2(CF3)3-(2,4,6) with an excess of Fe2(CO)9.
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