A DIPOLE-MOMENT ANALYSIS OF ARYLPHOSPHINES AND PHOSPHOLES

A dipole moment analysis of P-phenylphosphines, P-phenylphospholane and P-butylphosphole enables their P(3p-C(2pπ) and C(2pπ)-P(3d) electronic interactions, involving the phenyl or phosphyl group, the former interaction being the greater, to be discussed. It appears that the phosphole system can be regarded as weakly 'aromatic' in the sense that the P(3p)-C(2pπ) mesomeric effect is small, and much lower than the similar effect in pyrrole. An attempt was made to explain the dipole moment of P-phenylphosphole in terms of its two mesomeric moments (m(P-phenyl) and m(P-phosphyl)). Finally, the dipole moments of phosphacymantrene and 3,4-dimethylphosphacymantrene are analysed and their ring-moments and (ring-Mn(CO)3)-moments determined. © 1990.