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

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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.