Characterization of a dinuclear Mn(II) tri(μ-carboxylato) complex with the hindered hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (=TpiPr2) ligand: intramolecular hydrogen bonding interaction between the protonated TpiPr2 and Mn-coordinating carboxylate li

A dinuclear Mn(II) di(μ-hydroxo) complex having hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (=TpiPr2) reacted with benzoic acid to yield a dinuclear Mn(II) tri(μ-carboxylato) complex, TpiPr2Mn-(μ-OBz)3-Mn(TpiPr2H). X-ray crystallography reveals the unsymmetrical coordination environments for the manganese centers. One of the two TpiPr2 ligands, which bound to the five-coordinated Mn center, is protonated by the action of the third carboxylic acid and the resulting non-Mn-binding N–H moiety forms an intramolecular hydrogen bond with the oxygen donor of a carboxylate ligand. Steric congestion in the bimetallic core results in the large separation of the manganese centers bridged by the syn-anti carboxylate ligand.