Alan P. Marchand

NMR studies of rigid bicyclic systems. IV. NMR evidence regarding the nature and extent of molecular (polar solute-aromatic solvent) interactions in solution

Abstract The NMR spectrum of 1,4,7,7-tetrachloro-2,2,3,3-tetradeuterionorbomane (Ib) has been obtained in monosubstituted benzene solvents. The AA′BB′ NMR patterns of Ib thus obtained have been analyzed with the aid of the LAOCOON III computer program. The results of this analysis compared with the results of a similar solvent effect study involving Ib and 2-substituted-m-xylenes as solvents suggest the importance of the resonance contribution of the substituent X to the overall aromatic solvent effect. The Engler-Laszlo general solvation model appears to offer the best overall explanation of these results. Prior observations regarding the solvent effect of pyridine on the NMR spectrum of Ib have been reexamined and explained in terms of the general solvation picture.