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-μ-oxo and bis-μ-carboxylato groups, [Mn2(μ-O)2(μ-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(μ-O)4(μ3-O)4(μ-ArtolCO2)2(dmb)6]4+. Steric interactions between the bridging carboxylates and chelating pyridine-based ligands determine the nuclearity of the complexes formed.