Multinuclear magnetic resonance studies. Part 2. Diphosphanes and dithioxodi-λ5-phosphanes

Abstract

Carton-13 and phosphorus-31 n.rn.r. spectra have been obtained for a number of tetra-alkyldiphosphanes and tetra-alkyldithioxodi-λ⁵-phosphanes of general formulae (R¹R²P)₂ and [R¹R²(S)]₂ respectively. Some analogous compounds with phenyl substituents have also been studied. Satellite resonances in ³¹P resonance due to W.-containing isotopomers have been examined. The data are treated, together with ¹H n.m.r. studies where appropriate, to obtain (P,P) and (P,C) coupling constants, as well as ¹³C and ³¹P chemical shifts. These n.m.r. parameters are discussed in terms of steric interactions and stereoisomerism. The values of |¹J_pp| for both series of compounds increase markedly as the size of the substituents increases. and this effect correlates with an increase in δ_p.