Reactant or reagent? Oxidation of H2 at electronically distinct nickel-thiolate sites [Ni2(μ-SR)2]+ and [Ni–SR]+

Abstract

The chemical bond between a Lewis-acidic metal and a Brønsted/Lewis-basic sulphur donor provides M–S structures with functional properties that are relevant for a variety of processes such as the heterolytic cleavage of H₂. Direct comparison of reactivity properties between molecular M–S structures can be difficult owing to divergent electronic properties of stabilizing ligand scaffolds. This work reports on a mechanistic study of stoichiometric H₂ oxidation at electronically distinct [Ni₂(μ-SR)₂]⁺ and [Ni–SR]⁺ structures that derive from the same 1,4-terphenyldithiophenol ligand. In this context, the effect of metal containing side-products such as [HNi(PMe₃)₄]⁺ on overall H₂ oxidation reactivity displayed by Ni–S structures has been investigated quantitatively in addition to external parameters such as solvent and H₂ pressure.