Structure and electronic properties of Pd(III) complexes

Despite the rich chemistry of palladium in oxidation states of 0, +2, and +4, no Pd-III coordination compounds have been reported until the 1980s. Moreover, while Pd complexes are among the most commonly used catalysts in organometallic chemistry, the first organometallic Pd-III complexes have only been reported in 2006. Since then, a significant number of Pd-III complexes have been isolated, characterized, and proposed as active catalytic intermediates in the functionalization of C-H bonds, oxidatively induced C-C bond formation reactions, as well as radical insertion and addition reactions. This review provides an overview of the synthesis and spectroscopic characterization of mononuclear and dinuclear Pd-III complexes. A detailed understanding of the steric and electronic properties of Pd-III complexes should provide insight for the development of novel catalysts for multi-electron redox reactions and various organometallic transformations. (C) 2012 Elsevier B.V. All rights reserved.