The molecular structure of a germacyclobutane by gas electron diffraction and ab initio molecular orbital calculations

Autor: Haaland, Arne, Samdal, Svein, Strand, Tor G., Tafipolsky, Maxim A., Volden, Hans Vidar, van de Heisteeg, Bartholomeus J.J., Akkerman, Otto S., Bickelhaupt, Friedrich
Zdroj: Journal of Organometallic Chemistry; May 1997, Vol. 537 Issue: 32-40 p217-221, 5p
Abstrakt: The molecular structure of 1,1,3,3-tetramethylgermacyclobutane has been determined by gas electron diffraction supplemented by ab initio calculations at the HF/6–31G* and MP2/6-31G* levels. Structure refinement of a CS model with the differences between symmetry inequivalent Ge-C and C-C bond distances fixed at the HF values yielded the bond distances Ge-C = 197.5(3) and C-C = 156.7(2)pm (endocyclic) and Ge-C = 195.9(3) and C-C = 152.9(2)pm (exocyclic). The endocyclic valence angles are ∢CGeC = 75.3(2)°, ∢GeCC = 89.5(2)° and ∢CCC = 100.7(3)°. The exocyclic ∢CGeC = 108.8(8)°. The central ring is non-planar with a puckering angle of 24(2)°, the barrier to planarity is estimated to be V0 = 4.2(8)kJ mol−1. Optimisation of the structure of 1,1-dimethylgermacyclopropane at the HF/6-31G* level yields ∢CGeC valence angles of 47.5° (endocyclic) and 116.2° (exocyclic).
Databáze: Supplemental Index
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