Dialkylgallium Complexes with Alkoxide and Aryloxide Ligands Possessing N‑Heterocyclic Carbene Functionalities: Synthesis and Structure

Methods for the synthesis of dialkylgalium compounds with alkoxide or aryloxide ligands possessing N-heterocyclic carbene functionalities have been established. As a result, the synthesis of a series of dialkylgallium complexes Me₂Ga­(O,C) (<b>1</b>, <b>3</b>–<b>5</b>), and Me₂Ga­(O,C)·Me₃Ga (<b>2</b>, <b>6</b>) is described, where (O,C) represents an alkoxide or aryloxide monoanionic chelate ligand with an N-heterocyclic carbene functionality. All complexes have been fully characterized using spectroscopic and X-ray techniques. The presence of a strongly basic NHC functionality in alkoxide or aryloxide ligands resulted in the formation of monomeric Me₂Ga­(O,C) species. The reaction of those complexes with the Lewis acid Me₃Ga leads to Me₂Ga­(O,C)·Me₃Ga adducts (<b>2</b> and <b>6</b>) with a strong Me₃Ga–O dative bond. The effect of (O,C) ligands with various steric and electronic properties on the structure of obtained Me₂Ga­(O,C) and Me₂Ga­(O,C)·Me₃Ga has been discussed on the basis of spectroscopic data. Finally, the bond valence vector model has been used to estimate the effect of a chelating (O,C) ligand on strains in complexes <b>1</b>–<b>6</b> on the basis of X-ray data