Multinuclear oxo-bridged manganese complexes with a bulky substituted benzoate ligand: novel species obtained by using steric control.

A sterically hindered carboxylate ligand is used to synthesize the first transition metal complex containing both bis-mu-oxo and bis-mu-carboxylato groups, [Mn2(mu-O)2(mu-ArtolCO2)2(bpy)2]+. However, methyl substitution on the chelating bipyridine ligand results in the formation of a strikingly different and novel hexanuclear species, [Mn6(mu-O)4(mu3-O)4(mu-ArtolCO2)2(dmb)6]4+. Steric interactions between the bridging carboxylates and chelating pyridine-based ligands determine the nuclearity of the complexes formed.