Gallium and Indium Complexes in Organic Synthesis

Abstract

Gallium and indium complexes have developed as versatile substitutes for standard Lewis acid catalysts enabling its efficient applicability toward various synthetic methodologies. In comparison to group 13 halides, In(III) and Ga(III) halides are considered as softer Lewis acid catalyst, due to its large atomic size which promotes the activation of several functional groups under extremely mild conditions. Clearly evident from the fact that gallium and indium metal have low-slung ionizing energy of 5.99 and 5.8eV, respectively, enabling it to undergo SET (single electron transmission) reactions. Owing to the divergent physical properties such as non-reactivity toward air and moisture, making it suitable to recycle and recover economically while being inexpensive and non-toxic favors easy handling of reactions. Gallium and indium halides have been successfully used as potential Lewis acid catalysts in various organic transformations e.g. allylation, radical reactions, cycloaddition reactions, alkylation, coupling reactions etc. In this article, we seek to analyze the widespread use and applications of gallium and indium complexes in organic synthesis.