Magnetic non-equivalence in some derivatives of tetracoordinate phosphorus

Abstract

Magnetic nonequivalence of chemically equivalent protons and methyl groups has been observed in a number of phosphorus compounds containing chloromethyl or isopropyl groups attached to an asymmetric tetracoordinate phosphorus atom. The observed spectra have been interpreted on the basis of conformational averaging of chemical shifts and coupling constants, assuming that rotation about phosphorus-carbon bonds is rapid on the NMR time scale. The effects of solvents on the NMR spectra suggest that dipole-dipole association occurs in the pure compounds and that weak complexes are formed between the phosphorus derivatives and aromatic solvents.