Symmetric triazolylidene Ni(II) complexes applied as oxidation catalysts

A set of related Ni(II) complexes of N-heterocyclic carbene ligands (NHC) [trans-X2Ni(NHC)(2)] (X = Cl, I) bearing linear straight chain alkyl wingtip substituents have been synthesised and fully characterised. Single crystal XRD data revealed symmetrically aligned Ni(II) centres within square planar coordination of trans halide, trans NHC ligands. The complexes were used for the catalytic oxidation of alkanes under mild conditions in conjunction with tert-butyl hydroperoxide as an oxidant. Under optimised reaction conditions, the catalytic results pointed to good activities of circa 15% and 19% for cyclohexane and n-octane respectively. Furthermore, the catalytic systems are shown to be very efficient for the oxidation of linear alcohols to corresponding ketones. (C) 2018 Elsevier Ltd. All rights reserved.