The 1H n.m.r. spectra of an extensive series of complexes, cis- and trans-MX2L2, M2X4L2, and [Ph4P][MX3L](M = PdII or PtII, X = Cl, Br, I, or CN, and L = Me3P or Me3As) as well as AuXL have been measured. The spectra of MX2L2 were correlated with stereochemistry and, from an analysis of the spectra of the cis-isomers, 2JPP was evaluated. The complexes, trans-MX2(Me3P)(Me3As) were also studied to give 2JPH and 4JPH for trans-isomers. The relationship of the n.m.r. parameters to the bonding in the complexes is discussed.