Nuclear magnetic resonance studies of Lewis acid-base interactions. Part II. A correlation between isotropic contact shifts and taft σ* values for some pyridine base adducts of nickel(II) bis(O-alkyl dithiocarbonates) and bis(β-diketonates)

Yau Y. Lim, Kee L. Chua

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Abstract

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.

Original languageEnglish
Pages (from-to)1917-1920
Number of pages4
JournalJournal of the Chemical Society, Dalton Transactions
Issue number19
DOIs
Publication statusPublished - 1975
Externally publishedYes

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