31P–31P SPIN-SPIN COUPLINGS IN SYMMETRICAL AND UNSYMMETRICAL DERIVATIVES OF P(NMeNMe)3P

Abstract

The syntheses and characterization of seven new unsymmetrical derivatives of the type YP(NMeNMe)₃PZ are reported. Where Y = O or NPh: Z = S, Se, Br⁺ and where Y = a lone pair, Z = Br⁺ Also reported are the new symmetrical derivatives where Y = Z = (OC)₅W or (OC)₃Ni and the new monovalent cage cations YP(NMeCH₂)₃CMe⁺ where Y = Ph₃C and Br. Conductivity and ³¹P nmr evidence for the formulation of the phosphonium cations is presented. ³J³¹P³¹P couplings, obtained directly from the ³¹P nmr spectra of the unsymmetrical derivatives, are found to rise upon successively oxidizing the phosphorus atoms, and a rationale is offered. This coupling is also extracted from the ¹⁸³W and ⁷⁷Se satellite peaks in the ³¹P spectra of the symmetrical derivatives where Y = Z = (OC)₅W and Se, respectively.

A self-consistent set of assignments of the ³¹P chemical shifts is arrived at for YP(NMeNMe)₃PZ compounds and the useful role of LIS reagents in analyzing their proton spectra is delineated. The ¹³C nmr spectral parameters of these derivatives are also presented.