The Lewis acid-base interaction between pyridine bases and various O-alkyl dithiocarbonates and β-diketonates of NiII has been studied by n.m.r. spectroscopy. There is correlation between the isotropic contact shifts of the H2 and H3 protons of pyridine bases and the Taft σ* values of the substituent group R in [Ni(S2COR)2]. An explanation, based on a detailed study of the change in energy levels of the individual metal d orbitals, is proposed for the observed correlation which implies the relative strength of the Lewis acid-base interaction can be inferred from contact-shift studies. The observed trend in relative isotropic shifts of the protons at the 3-Me, 4-Me, and H4 positions and the absolute isotropic shifts of the H2 protons on the spin-delocalization mechanism is also discussed.
|Number of pages||4|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 1975|