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  • 1
    Electronic Resource
    Electronic Resource
    Electronic Interactions in Saturated and Unsaturated [1.1.1]-, [2.1.1]-, [2.2.1]-, and [2.2.2]Triblattanes  -  PE-Spectroscopic Investigations (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2299-2307 
    Details
    ISSN: 0009-2940
    Keywords: Triblattanes ; PE ; Orbital sequence ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(I)-PE spectra of the parent [1.1.1]-, [2.1.1]-, [2.2.1]-, and [2.2.2]triblattanes 1-4, of their unsaturated or ketonic congeners 5-13 and benzo derivatives 14-20 have been recorded. For 1-4, the energy difference between the highest occupied orbitals (e” and a' mainly localized at the central bicyclo-[2.2.2]octane unit) and the subsequent MOs increases with increasing number of ethano bridges. This observation is rationalized by using a first-order perturbation-theoretical approach. The analysis of the PE spectra of the exo-methylene (5-7), ketone (8-10), and endo-olefinic derivatives (11-13) unveils a strong π/σ mixing. The splitting of the π-bands in 7 (0.95 eV) and 13 (1.0 eV), respectively, is traced back to a stronger π/σ mixing of the e MOs as compared to the a2 MOs. An analogous interaction causes the splitting of the first bands of the ketones 8-10 (0.45-1.49 eV). For the benzo derivatives 14-20 the split of the π-bands is relatively small (0.35-0.7 eV).
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261019
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  • 2
    Electronic Resource
    Electronic Resource
    Substituenteneffekte auf die Struktur von Spiropentan (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2503-2512 
    Details
    ISSN: 0009-2940
    Keywords: Spiropentanes, derivates of, molecular structures of, substituent effects in ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects on the Structure of SpiropentaneIn order to investigate the influence of substituents on the bond lengths of the spiropentane framework, the molecular structures of the spiropentane derivates 1-7 have been determined by X-ray analysis. The π acceptor substituents (CO, CO2R, Ph) shorten the distal bond of the substituted three-membered ring by δ = -0.02 Å. The vicinal bonds are lengthened by δ/2. The π donor-s̰ acceptor groups have the opposite effect [δ(Cl2) = 0.019, δ(F2) = 0.056 Å]. The influence of several substituents is additive. The longer peripheral bond [1.530(14) Å] is varied to the same degree as the shorter central bond [1.482(9) Å]. The second three-membered ring of the spiropentane system is not affected. These results are explained qualitatively by considering the valence MO′s of a distorted spiropentane. Quantum chemical calculations using a 3-21 G basis set confirm this picture.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251124
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of 1-Azacyclododeca-3,8-diynes and 1,6-Diazacyclododeca-3,8-diynes (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2113-2118 
    Details
    ISSN: 0947-3440
    Keywords: Medium-sized rings ; Cyclizations ; Alkynes ; Heterocycles ; Multicomponent reactions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of N,N′-dialkyl- and N,N′-diaryl-1,6-diazacyclodeca-3,8-diynes was achieved by reaction of alkyl- or arylamines with 1,4-dihalobut-2-yne under dilution conditions in yields of 5-15%. The compounds synthesized by this procedure were the N,N′-dimethyl (2b), N,N′-diethyl (2c), N,N′-diisopropyl (2d), N,N′-di-tert-butyl (2e), N,N′-dicyclohexyl (2f), N,N′-diphenyl (2g), and N,N′-di-p-tolyl (2h) derivatives. The parent compound 2a was obtained in ca. 40% yield by heating 2d with α-chloroethylchloroformate (20). Using 1,9-dibromonona-2,7-diyne (10) and methylamine or isopropylamine, respectively, the corresponding N-alkyl-1-azacyclodeca-3,8-diynes 4b and 4d were synthesized under dilution conditions. By heating 4d with 20 we obtained 1-azacyclodeca-3,8-diyne (4a). As side products of the cyclization reactions the trimers 18 and tetramers 12 and 19 were isolated and characterized. N-methyl-1-azacycloundeca-3,9-diyne (14b) was prepared by reaction of 1,10-dibromodeca-3,8-diyne (13) with methylamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971013
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  • 4
    Electronic Resource
    Electronic Resource
    Replacement of One CO Unit in Dicarbonyl(η5-cyclopentadienyl)cobalt Derivatives by Bis(tert-butylsulfonyl)acetylene (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 629-632 
    Details
    ISSN: 1434-1948
    Keywords: Alkyne complexes ; Carbonyl complexes ; Cobalt ; CO replacement ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of dicarbonyl(η5-cyclopentadienyl)cobalt (1) and some of the Cp-ring substituted congeners with bis(tert-butylsulfonyl)acetylene (BTSA) results in the replacement of one CO group by the BTSA moiety. The variation of the yields and reaction times indicates a dependence of the reactivity of 1-6 with BTSA as a function of substituents. X-ray investigations of the products show that the alkyne unit is strongly bound to the metal.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Reactions of 1,8-Diheterocyclotetradeca-4,11-diynes with (η4-Cycloocta-1,5-diene)(η5-cyclopentadienyl)cobalt (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 499-504 
    Details
    ISSN: 1434-1948
    Keywords: Alkynes ; Heterocycles ; Cyclizations ; Cobalt ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The following monocyclic and bicyclic 14-membered diynes were treated with [CpCo(cod)]: 1-oxacyclotetradeca-4,11-diyne (2), 1,8-dioxacyclotetradeca-4,11-diyne (3), cyclotetradeca-4,11-diynone (4), cyclotetradeca-4,11-diyne-1,8-dione (5), 1,1,8,8-tetramethyl-1,8-disilacyclotetradeca-4,11-diyne (6), 1-allyl-1-azacyclotetradeca-4,11diyne (7), 1,8-dipropyl-1,8-diazacyclotetradeca-1,11-diyne (8), 1,8-diallyl-1,8-diazacyclotetradeca-4,11-diyne (9), 1,8-diazabicyclo[6.6.4]octadeca-4,11-diyne (10), 1,8-diazabicyclo[6.6.6]eicosa-4,11-diyne (11), 1,10-diazabicyclo[8.6.6]docosa-13,19-diyne (12) and 1,12-diazabicyclo[10.6.6]tetracosa-15,21-diyne (13). In all cases we obtained an intramolecular cyclobutadiene complex stabilized with a CpCo fragment (15-26). For 3 we could isolate, besides the cyclobutadiene complex 16, the trimerization product 28. In the cases of 15, 16, 18, 20, 23, 25, and 26 the structure of the cylobutadiene complexes could be confirmed by X-ray studies. Common to all structures is a boat-like conformation of the tricyclic unit containing the cyclobutadiene ring. The two cycloheptene units adopt a chair conformation in which the heteroatom is removed from the metal center.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and Structural Properties of Bridged 1,8-Diazacyclotetradeca-4,11-diynes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2803-2809 
    Details
    ISSN: 1434-193X
    Keywords: Alkynes ; Cyclizations ; Nitrogen heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 1,8-diazacyclotetradeca-4,11-diyne (4) was accomplished by reaction of 1,6-dibromo-3-hexyne (11) with ammonia. Similarly, the preparation of 1-azacyclotetradeca-4,11-diyne (5) was achieved from 1,13-dibromotrideca-3,11-diyne (10) and ammonia. The reaction of α,ω-diamines of linear hydrocarbons of the chain length C4 to C10 with 11 yielded the corresponding bicyclic diynes 23-29. The reaction of 4 with 11 yielded 1,8-diazabicyclo[6.6.6]icosa-4,11,16-triyne (14). Similarly, the reaction of 4 with 1,4-dibromo-2-butyne yielded 1,8-diazabicyclo[6.6.4]octadeca-4,11,16-triyne (31). The molecular structures of 1,8-diisopropyl-1,8-diazacyclotetradeca-4,11-diyne (13a), as well as of 14, 24, 27 and 31 were studied by means of the X-ray technique. It was found that 13a adopts a chair-like conformation (C2h) with an equatorial orientation of the isopropyl groups. In 14, 24, 27, and 31 the 14-membered rings adopt a twist-boat conformation. The distance between the nitrogen atoms varies between 4.662(2) and 5.189(2) Å. In the case of 14, 24 and 27 the nitrogen atoms are pyramidalized and point inside the cage while in 31 the substituents at each nitrogen atom and the nitrogen atoms are situated in one plane.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation and Structures of Cyclotetradeca-4,11-diynone, Cyclotetradeca-4,11-diyne-1,8-dione, Their Exomethylene Derivatives, and 1,8-Dioxacyclotetradeca-4,11-diyneDedicated to Professor Gottfried Huttner on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1545-1550 
    Details
    ISSN: 0947-3440
    Keywords: Medium-sized rings ; Alkynes ; Conformation analysis ; Ketones ; Cyclizations ; Ether ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The following 14-membered ring diynes have been synthesized: cyclotetradeca-4,11-diynone (4), cyclotetradeca-4,11-diyne-1,8-dione (6), the corresponding exomethylene derivatives 5 and 7, as well as 1,8-dioxacyclotetradeca-4,11-diyne (8). The synthesis of the diketal of 4 was achieved by the reaction of the ethylene ketal of 1,5-dibromopentan-3-one (9) with the dilithium salt of 1,8-nonadiyne. Similarly, the diketal of 6 was prepared from the dilithium salt of the ethylene ketal of 1,8-nonadiyn-5-one 11 with 9. The unprotected ketones 4 and 6 were obtained by treating the ketals 10 and 14, respectively, with HCl. The ketones 4 and 6 were transformed to the exomethylene derivatives by a Wittig reaction. The reaction of the dilithium salt of 5-oxanona-1,8-diyne (16a) with 1,5-dibromo-3-oxapentane (15) yielded 8. X-ray investigations of single crystals of 6 and 8 revealed chair conformations with a zig-zag arrangement, employing two anti orientations of the two chains between the triple bonds. A zig-zag arrangement of the chain containing the carbonyl group was also found in 4. In 3b and 7 Ci symmetry was found, with only one anti conformation in each chain. Molecule 6 crystallizes with C2h symmetry and 8 with a center of symmetry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970734
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation and Properties of Stelladiones (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 171-176 
    Details
    ISSN: 1434-193X
    Keywords: Stelladiones ; Photoelectron spectroscopy ; Calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tricyclo[3.3.0.03,7]octane-2,4-dione (2,4-stelladione, 3), tricyclo[3.3.0.03,7]octane-2,6-dione (2,6-stelladione, 4), and 2-oxotricyclo[3.3.0.03,7]octane-6-thione (5) were synthesized. Key steps in the procedures were a Paterno-Büchi reaction followed by an oxetane splitting with a strong base. Structure analysis on single crystals of 4 and 5 revealed long central C-C bonds (1.59 Å) of the stellane skeleton. The He(I) photoelectron spectra of 3, 5, and 4-methylenetricyclo-[3.3.0.03,7]octan-2-one (9) were recorded and interpreted on the basis of quantum-mechanical calculations (HF-SCF, 6-31G* basis). The large energy difference between the first PE bands of 3 (0.8 eV) is due to a strong interaction between the lone pairs on the oxygen atoms and the σ frame.
    Type of Medium: Electronic Resource
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