Approaches to alkane functionalization with Tp′Pt and (nacnac)Pt reagents

Abstract

In this perspective article we give an overview of our studies of C–H activation with platinum over the past decade. The scorpionate ligand Tp′ (Tp′ = hydrotris(3,5-dimethylpyrazolyl)borate) has exhibited the ability to stabilize both Pt(IV) and Pt(II) complexes due to flexibility between κ3 and κ2 binding modes. Control of the Tp′ coordination mode and Pt oxidation state is tightly coupled with acid/base chemistry. This ability allowed us to model a spectrum of intermediates in C–H activation reactions, including Pt(IV) alkyl hydrides, five-coordinate Pt(IV) silyl hydrides, and Pt(II) benzene complexes. We have been able to observe sturdy Pt(II) benzene complexes and probe their equilibria with the respective C–H activated Pt(IV) species in the presence of an added ligand. We have also taken steps toward functionalizing hydrocarbons with Tp′Pt by dehydrogenation of alkanes and by arylation of olefins. We have recently turned to bidentate nacnac (nacnac = N-phenyl-β-enamineimine) ligands in the hopes of catalytically functionalizing hydrocarbons.Key words: C–H activation, reductive elimination, Tp′Pt, five-coordinate, β-diiminate.