Studies in structural chemistry - Dipole moments in relation to molecular structure

Abstract

The dipole moments of p-chlorophenyldichlorophosphine (2.28 D) and p-bromophenyldichlorophosphine (2.04 D) have been determined in benzene at 35 °C. Applying the method of Smith et al., the formal charge distribution in and the dipole moments of a few organophosphines and arsines have been evaluated. The difference in the moment between the observed and the calculated moments are explained on the basis of back bonding and hyperconjugative effect in alkylhaloarsines. The mesomeric effect operating in the aromatic systems are evaluated by comparing the moments with the corresponding aliphatic ones. In unsaturated compounds the differences are attributed to mesomeric effects involving the expansion of arsenic valence shell.