γ-1-phenylsilatrane crystallizes in the monoclinic space group P21/n, with a 8.475, b12.949, c 11.122 » and β 90.86°. The structure was determined by direct methods and was refined to R 0.078 for 1687 observed reflexions and 0.081 for all 1813 reflexions. The →Si bond length is 2.132(4), SiC is 1.894(5) ». The mean SiO bond distance is 1.656 Å, angle NSiC is 179.0(2)°. The average NSiO, CSiO and OSiO angles are 83.6, 96.4 and 123.5°. By use of published data for six other silatrane molecules, some structural features were established. Thus, the length of the N→Si bond is affected by the other apical substituents of the silicon atom, the number of oxygen atoms attached to it and steric effects. Increase in the length of the dative N→Si bond is accompanied by further distortion of the trigonal bipyramidal configuration and of the tetrahedron around the nitrogen atom. The relatively long SiC(sp2) bond may be due to decrased dπpπ interaction. The crystalline modifications (α, β, ψ) of the 1-phenyl-derivative possibly result from rapid ring-inversion in solution.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
- Materials Chemistry