Steric and Electronic Effects on the 103Rh NMR Chemical Shifts of RhI(cyclooctadiene) Compounds Bearing NDonor Ligands

In order to study electronic and steric effects on (delta)(103Rh), the 103Rh-NMR spectra of a series of [Rh(cod)L2] complexes (with L = nitrogen, oxygen, or chloride) have been measured by gradient-enhanced HMQC (1H,103Rh) NMR spectroscopy. Density functional computations of representative examples have been performed at the GIAO-B3LYP level of theory. The obtained experimental values of 103Rh shifts fit the generally observed trend of coordinating ligands in the first coordination sphere of the metal: P < N < O. Calculated 103Rh shifts agreed to within 8 % with experimental values. The computational results indicate that the Rh-N bond distance has a larger influence on the chemical shift than the N-Rh-N angle.