Nuclear magnetic resonance and infrared studies of N^15-substituted trimethylsilyl-, -germyl-, and -stannylanilines. A Test of (p->d)-.pi. interactions in Group IV nitrogen bonds

Abstract

Infrared and proto n magnetic resonance spectra of the aniline-N14 and -N15 isotopomers and their N-trimethylsilyl, -germyl, and -stannyl derivatives have been measured and compared. Nmr assignments have been checked by comparisons of proton spectra at 60 and 100 Mcps; by proton-N15 heteronuclear experiments at 9400 G; and by observation of N15 satellites. The one-bond "5-H couplings can be interpreted (on the assumption of a dominant Fermi spin-spin interaction, small radial variations for nitrogen wave functions, and equal distributions of s character in the sigma bonds) in terms of pyramidal arrangements of bonds at nitrogen. The relation of the stereochemical situation at nitrogen to the question of (p-->d)-pi or (p-->p)-pi bonding involving nitrogen is discussed.