Unsymmetrical bisphosphorus ligands. Phosphorus-31 and carbon-13 nuclear magnetic resonance and mass spectral measurements

Abstract

The unsymmetrical bisphosphorus ligands of the type RPhP[CH₂]₆PPh₂(R = Me, Et, and cyclohexyl), R₂P[CH₂]_nPPh₂(R = Me and Et, n= 3 and 4), RPhP[CH₂]₄PPh₂(R = Me and Et), and EtPhP[CH₂]₃PPh₂ have been characterized by ³¹P and ¹³C n.m.r. spectroscopy and by mass spectral measurements. The variation in the ³¹P chemical shift is explained in terms of the steric requirements of the substituent groups attached to phosphorus and the ¹³C n.m.r. of the trimethylene-bridged diphosphines are compared and contrasted with their dimethylene-bridged analogues.