Nuclear magnetic resonance spectra of some silyl and trimethylsilyl pseudohalides

Proton, 13C, 15N, and 29Si n.m.r. spectra have been recorded for SiH3(CN), SiH3(NCY)(Y = O, S, or Se), and SiMe3(CN) at room temperature or below, as has the 77Se spectrum of SiH3(NCSe). The spectra show no sign of the presence of other isomers, nor of any intermolecular exchange that is fast on the n.m.r. time scale. The n.m.r. parameters are given, together with T1 and nuclear Overhauser enhancement measurements, for SiMe3(CN) at three different temperatures. The spin-rotation contribution to relaxation appears to be dominant.