Helene Schei, Quang Shen, Robert F. Cunico
1980
Citations
0
Influential Citations
14
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract The structure of 1 -chloro-1 -si labicyclo( 2.2.2 )octane is determined by gas-phase electron diffraction. The molecule is found to have a large amplitude twisting motion with a double minimum quartic potential function of the form V (φ) = V o [1 + (φ/φ o ) 4 - 2(φ/φ o ) 2 ]. Least-squares analysis of the experimental data gives values of 1.4(0.8) kcal mole − for V o and 17.5(2.5)° for φ o . Other structural parameters for the “quasi- C 3v ” cage-like molecule include: r g (Si-Cl) = 2.061(3) A, r g (Si-C) = 1.863(3) A, r g (C-C av ) = 1.559(2) A, and r g (C-H av ) = 1.098(7) A. Several valence angles exhibit large deviations from tetrahedral values, e.g. ∠Cl-Si-C 2 = 114.6(0.2)°, ∠Si-C 2 -C 3 = 105.8(0.4)°, ∠C 2 -C 3 -C 4 = 114.2(1.2)°, ∠C- 3 -C 4 -C 5 = 111.4(0.8)° and ∠C 2 -Si-C 6 = 103.9(0.2)°. Many of the structural features in this strained polycyclic compound. Including the nature of the quartic potential function, can be rationalized in terms of a simple molecular mechanics model. A new method for the calculation of an analytical Jacobian of the intensity function with respect to parameters of the potential function is also discussed.