Nuclear magnetic resonance study of intramolecular electronic effects in diphenyl sulfides, sulfoxides, and sulfones

A nuclear magnetic resonance (n.m.r.) method has been applied to the study of variations in electron density in the aromatic rings of para-disubstituted diphenyl sulfides, sulfoxides and sulfones. The n.m.r. response of the aromatic ring protons has been determined as a function of the nature of the para substituents and particularly as a function of the nature of the bridging group between the rings. Certain diphenyl ethers and diphenyl methanes have been investigated for comparison purposes. The results establish that a transmission mechanism is operative through sulfur in diphenyl sulfides that is not effective when the bridging function is sulfoxide or sulfone. The extent to which transmission is operative even in the sulfides is dependent on the precise nature of the para substituents, in particular whether they are donors or acceptors and the manner in which they interact with the remainder of the molecule.