Employing Aryl-Linked Bis-mesoionic Carbenes as a Pincer-Type Platform to Access Ambient-Stable Palladium(IV) Complexes.

Abstract

The study of palladium(IV) species has great implications for PdII /PdIV -mediated catalysis. However, most of the PdIV complexes rapidly decompose under ambient conditions, which makes the isolation, characterization and further reactivity study very challenging. The reported ancillary ligand platforms to stabilize PdIV species are dominated by chelating N-donors such as bipyridines. In this work, we present two PdIV complexes with scarcely used C-donors as the supporting platform. The anionic aryl donor and MIC (MIC=mesoionic carbene) are combined in a [CC'C]-type pincer framework to access a series of ambient-stable PdIV tris(halido) complexes. Their synthesis, solid-state structures, stability, and reactivity are presented. To the best of our knowledge, the work presented herein reports the first isolated PdIV -MIC as well as the first PdIV carbene-based aryl pincer.