Crystal structure of a seven-coordinate manganese(II) complex with tris(pyridin-2-ylmethyl)amine (TMPA)

Abstract

Structural analysis of (acetato-κ2 O,O′)(methanol-κO)[tris(pyridin-2-ylmethyl)amine-κ4 N,N′,N′′,N′′′]manganese(II) tetraphenylborate, [Mn(C2H3O2)(C18H18N4)(CH3OH)](C24H20B) or [Mn(TMPA)(Ac)(CH3OH)]BPh4 [TMPA = tris(pyridin-2-ylmethyl)amine, Ac = acetate, BPh4 = tetraphenylborate] by single-crystal X-ray diffraction reveals a complex cation with tetradentate coordination of the tripodal TMPA ligand, bidentate coordination of the Ac ligand and monodentate coordination of the methanol ligand to a single MnII center, balanced in charge by the presence of a tetraphenylborate anion. The MnII complex has a distorted pentagonal–bipyramidal geometry, in which the central amine nitrogen and two pyridyl N atoms of the TMPA ligand, and two oxygen atoms of the acetate ligand occupy positions in the pentagonal plane, while the third pyridyl nitrogen of TMPA and the oxygen from the methanol ligand occupy the axial positions. Within the complex, the acetate O atoms participate in weak C—H...O hydrogen-bonding interactions with neighboring pyridyl moieties. In the crystal, complexes form dimers by pairs of O—H...O hydrogen bonds between the coordinated methanol of one complex and an acetate oxygen of the other, and weak π-stacking interactions between pyridine rings. Separate dimers then undergo additional π-stacking interactions between the pyridine rings of one moiety and either the pyridine or phenyl rings of another moiety that further stabilize the crystal.