LAUSR

Half-sandwich nickel complexes bearing a variety of mesoionic N-heterocyclic carbene ligands (η5-cyclopentadienyl)-iodo-{1-(R)-3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium-5-yl}nickel; where R = phenyl (3a); 2-ethoxy-2-oxoethyl (3b); propyl (3c); benzyl (3d) were synthesized by the reaction of nickelocene with the respective triazolium salts. The complexes were characterized by HRMS and multi-nuclear NMR, and the solid state structures of 3c and 3d were elucidated by single crystal X-ray diffraction analysis in which both complexes displayed a trigonal planar geometry. As catalysts for the oxidation of n-octane in the presence of oxidants under mild reaction conditions, all the complexes showed activity for the substrate yielding a range of oxygenated products. Under optimized reaction conditions, catalyst 3c with lighter substituents on the triazolium ring exhibited the highest catalytic activity of 15% total conversion to products. With H2O2 as the more productive oxidant, the preferential activation of internal carbons led to the observation of a mixture of octanones as the dominant product stream of the oxidation reaction.