Group 13 metal (Al, Ga, In, Tl) complexes supported by heteroatom-bonded carbene ligands

• The synthesis, structural characterization and reactivity of group 13 metal heteroatom-bonded complexes is reviewed.
• N-Heterocyclic carbene (NHC) group 13 species are dominant in the field and typically form robust and thermally stable entities of the type (NHC)MX3.
• NHC ligands may also stabilize low valent Ga, In and Tl compounds.
• This class of compounds constitutes an emerging class of robust species of potential usefulness in catalysis.

The present contribution comprehensively reviews the synthesis, structural characterization and current applications of group 13 metal complexes supported by heteroatom-bonded carbene ligands. Detailed structural analysis and comparison of the structure/reactivity trends of group 13 metal carbene species constitute the primary purpose of the present contribution. The current use and applications of this class of compounds are also discussed. In general, such adducts have been thoroughly characterized (both in solution or in the solid state) and structural data, frequently supported by theoretical investigations, provided insight into the stability/reactivity of the adducts formed. While essentially dominated by Arduengo-type NHC adducts, N- and P-bonded cyclic and acyclic carbene complexes of Al, Ga and In have also been recently described, including the recent use of “carbon(0) ligands”. In general, recent developments in carbene group 13 species exploit the improved stability of the resulting metal complexes for either the isolation/characterization of unprecedented structural motifs or the production of robust group 13 metal reagents subsequently used for organic substrates functionalization or in catalysis.