Thermal Hydrogen-Atom Transfer from Methane: The Role of Radicals and Spin States in Oxo-Cluster Chemistry

Hydrogen-atom transfer (HAT), as one of the fundamental reactions in chemistry, is investigated with state-of-the-art gas-phase experiments in conjunction with computational studies. The focus of this Minireview concerns the role that the intrinsic properties of gaseous oxo-clusters play to permit HAT reactivity from saturated hydrocarbons at ambient conditions. In addition, mechanistic implications are discussed which pertain to heterogeneous catalysis. From these combined experimental/computational studies, the crucial role of unpaired spin density at the abstracting atom becomes clear, in distinct contrast to recent conclusions derived from solution-phase experiments. The need for spin: Owing to its importance for numerous chemical processes, the nature of hydrogen-atom transfer (HAT) has become a major area of research. This Minireview shows the intrinsic requirements that enable gaseous oxo clusters to bring about HAT reactivity from saturated hydrocarbons at room temperature, thus revealing the crucial role of unpaired spin density at the abstracting atom. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.