Comparison of the electron diffraction and ab initio structures of neopentane and di-tert-butyl methane
by Siam, K.; Ewbank, J. D.; Schaefer, Lothar
The mol. structures of neopentane (NP) and di(tert-butyl) methane (DTBM) were detd. by ab initio gradient-geometry refinements on the 4-21G level. The structure calcd. for DTBM agrees with the steric deformations previously inferred by an exptl. underdetd. electron-diffraction anal. (Baretll and Bradford, 1977). The av. C-C bond distance is stretched by 0.008 Å from the neopentane ref. value (exptl. value 0.008 Å). The central C-C-C bond angle is opened to the extreme value of 124.2° (exptl. value 125-128(6)°). The Me carbons in adjacent tert-Bu groups are twisted away from the perfectly staggered positions by 11.6-16.5° (exptl. value 15 ± 6°). Calcd. av. C-H and C-C bond distances (rg) are 1.118(10) and 1.536(3) Å, resp., for NP (exptl. values 1.114(8) and 1.537(3) Å); and 1.118(10) and 1.544(3) Å, resp., for DTBM (exptl. values 1.122(15) and 1.545(5) Å). Calcd. results for DTBM provide important structural trends, including significant differences in individual C-H and C-C bond distances, and asymmetry of tert-Bu and Me groups, not established exptl.
- Journal
- Journal of Molecular Structure-Theochem
- Volume
- 30
- Issue
- 1-2
- Year
- 1986
- Start Page
- 155-160
- URL
- https://dx.doi.org/10.1016/0166-1280(86)80094-x
- ISBN/ISSN
- 0166-1280
- DOI
- 10.1016/0166-1280(86)80094-x