Manganese(ii) chemistry of a new N3O-donor chelate ligand: synthesis, X-ray structures, and magnetic properties of solvent- and oxalate-bound complexes

Abstract

The synthesis and characterization of a new N₃O donor ligand N-benzyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine (bpppa) is reported. Treatment of bpppa with Mn(II)(ClO₄)₂·6H₂O in acetonitrile solution yielded the mononuclear [(bpppa)Mn(CH₃CN)(H₂O)](ClO₄)₂ (1) which was characterized by X-ray crystallography, elemental analysis, IR spectroscopy, mass spectrometry, and a solution magnetic moment measurement. Admixture of equimolar equivalents of bpppa and Mn(II)(ClO₄)₂·6H₂O in methanol solution, followed by addition of 0.5 or 1 equivalents of sodium oxalate, yielded the binuclear complex [{(bpppa)Mn}₂(μ-C₂O₄)](ClO₄)₂ (2), which was characterized by X-ray crystallography, elemental analysis, IR spectroscopy, mass spectrometry, and solid-state magnetic measurements. While 1 is mononuclear, the formation of the binuclear oxalate derivative 2 indicates that use of the bpppa ligand does not enable isolation of a complex that is structurally relevant to a proposed 1 ∶ 1 Mn(II)–oxalate adduct in the catalytic cycle of the oxalate degrading enzyme oxalate decarboxylase.