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) (1, 3–5), and Me2Ga(O,C)·Me3Ga (2, 6) 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 (2 and 6) 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 1–6 on the basis of
X-ray data.