AN ELECTRON DIFFRACTION INVESTIGATION OF SERIES OF COMPOUNDS SICLN(NCO)4-N (N=1,2,3)

The molecular structures of the sequence SiCln(NCO)4-n (n = 1,2,3) were determined by gas-phase electron diffraction. The observed Si-N bond lengths are 1.646 ± 0.008 Å in SiCl3(NCO), 1.687 ± 0.004 Å in SiCl2(NCO)2 and 1.684 ± 0.003 Å in SiCl(NCO)3; the valence angles at the nitrogen were found to be 138.0 ± 0.4°, 136 ± 1° and 145 ± 2° respectively. The Si-Cl bond length in SiCl3- (NCO) is 2.014 ± 0.005 Å; it agrees well with that found in SiCl4 (2.015 ± 0.002 Å); similarly, the Si-N bond length in SiCl(NCO)3 (1.684 ± 0.005 Å) is very close to that found in Si(NCO)4, 1.688± 0.003 Å. SiCl3(NCO) has C1 symmetry, while C2 and C3 symmetries best represent the diffraction data for SiCl2(NCO)2 and SiCl(NCO)3. © 1969.