Determination of 3J(31P31P) and 13C31P coupling constants in 1,6-diphosphatriptycene from carbon-13 n.m.r. lone pairs effects on 13C31P couplings

The ³¹P? ³¹P and ¹³C? ³¹P coupling constants in 1,6-diphosphatriptycene have been obtained from analysis of its proton decoupled ¹³C n.m.r. spectra. More accurate data, however, resulted from simultaneous analysis of the proton decoupled ¹³C spectra and ³¹P(¹³C) satellite spectra. The ¹³C? ³¹P couplings are strongly influenced by the proximity and orientation of the phosphorus lone pair electrons. The first ³¹P? ³¹P coupling in an aromatic diphosphine is reported.