Well-defined organo-gallium complexes as Lewis acids for molecular catalysis: Structure–stability–activity relationships

• The well-defined organo-gallium compounds that have been used as catalyst in molecular chemistry are reviewed.
• Structure–activity relationships are established.
• Structure–stability relationships are established.

While the coordination chemistry of gallium is very rich, only a few applications of organo-gallium compounds as catalysts for molecular transformations have been reported. Nevertheless, some studies containing both families of X-ray characterized species and their catalytic activity allow the establishment of a structure–activity and a structure–stability relationship. They show that coordination compounds of gallium enable reactions that encroach upon the territory of transition metals. The interest of using specific ligands in gallium catalysis is also becoming clear in classical Lewis acid chemistry. In this review, the physical properties of gallium complexes are analyzed and related to their ability to activate alkynes toward nucleophilic additions, peracetic acid toward olefin epoxidation, and aldehydes toward hetero Diels–Alder reactions.

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