The 2‐imino‐1,3‐selenazolidine group bonded to phosphorus and silicon: a multinuclear magnetic resonance study

A tris(imino)phosphane (3), its sulfide [3(S)], an iminodiphenylphosphane (4), and an iminotrimethylsilane (5), in all of which the imino group belongs to a pseudo ‐ephedrine‐derived 2‐imino‐1,3‐selenazolidine ring, were prepared and studied by multinuclear magnetic resonance ( 1 H, 13 C, 15 N, 29 Si, 31 P, 77 Se NMR). By application of various 1D and 2D NMR techniques, NMR parameters such as the isotope induced chemical shifts 1 Δ 14/15 N( 31 P) for 4, 1 Δ 14/15 N( 29 Si) for 5, numerous coupling constants and chemical shifts could be obtained. The absolute sign of 1 J ( 29 Si, 15 N) (>0) was determined for 5. The largest values so far for 3 J ( 77 Se, 31 P) (198.0 Hz in 3 and 194.0 Hz in 4) were observed, and the absolute sign of these coupling constants 3 J ( 77 Se, 31 P) > 0 was determined, together with the signs of various other coupling constants involving 77 Se or 31 P. Copyright © 2001 John Wiley & Sons, Ltd.