Nuclear magnetic resonance studies of scrambling reactions in solutions of tetra-alkyl- and tetra-aryl-diphosphanes

Abstract

The ³¹P-{¹H} nuclear magnetic resonances of certain tetra-alkyldiphosphanes are broadened on dissolution in methylene dichloride, the effect increasing with time. Simultaneously, the ¹³C-{¹H} and ¹H spectra indicate ‘decoupling’ from ³¹P. These observations suggest breakage of the P–P bond, and mixtures of certain diphosphanes give n.m.r. spectra which indicate exchange of parts, with the formation of new mixed species. The ³¹P chemical shifts and P–P coupling constants for such species are presented and discussed. In two cases ¹³C data have also been obtained.