Reactive main group metal complexes of the neutral NNNN macrocycle, Me4TACD

Currently, there is considerable interest in introducing molecularly defined main group metal compounds as precursors and model complexes of homogeneous catalysts for various bond cleavage and forming transformations. With a focus on the NNNN macrocyclic ligand Me<inf>4</inf>TACD (N,N′,N′′,N′′′-tetramethyl-1,4,7,10-tetraazacyclododecane), this review summarizes the versatility of the ligand Me<inf>4</inf>TACD for the stabilization of reactive main group s- and p-block (group 1, 2, 12-14) metals. Metal hydrides, hydrocarbyls and silyls are often monomeric and catalyze alkene hydrofunctionalisations. In contrast to the rich coordination chemistry of d- and f-block transition metals using a plethora of ligands, main group metals still leave room for new structures and reactivities, aligning with the current efforts to develop a systematic understanding in s- and p-block metal-ligand combinations.