PerspectiveOrganometallic Chemistry

Catalysis by nickel in its high oxidation state

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Science  13 Mar 2015:
Vol. 347, Issue 6227, pp. 1203-1204
DOI: 10.1126/science.aaa7553

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Summary

An oxidation state is a numerical value, assigned to an atom in a compound or ion, based on a set of rules such that the sum of the oxidation states equals the overall charge on the entity. The transfer of valence electrons changes the oxidation state of an atom, so oxidation states can help predict chemical reactivity. Nowhere is this concept more exploited than in catalysis with transition metals, which can readily access a variety of oxidation states. Small molecules or ions that bind to the metal as ligands influence the metal's molecular and electronic geometries, and the resulting changes in oxidation state can drive reactions of these ligands. On page 1218 of this issue, Camasso and Sanford (1) report an exquisite example of tuning the reactivity of a nickel (Ni) catalyst by the introduction of ligands and oxidants suitable to access an uncommon oxidation state, NiIV (2). They used the high oxidation state of Ni to drive the formation of carbon bonds to heteroatoms, specifically oxygen, sulfur, and nitrogen.