Synthesis and catalytic activity of manganese(II) complexes of pentanedioic acid;: X-ray crystal structure of [Mn(phen)2(H2O)2][Mn(O2C(CH2)3CO2)(phen)2H2O](O2C(CH2)3CO2)•12H2O (phen = 1,10-phenanthroline)

Reaction of manganese(II) acetate tetrahydrate with pentanedioic acid gives [Mn(O2C(CH2)(3)CO2)]. H2O (1). Complex 1 reacts with 1,10-phenanthroline (phen) (similar to 1:3 mol ratio) in ethanol giving the mono-phenanthroline complex [Mn(O2C(CH2)(3)CO2) (phen)] (2). Using less phenanthroline (similar to 1 mol of 1:2 mol phenanthroline) in an ethanol-water solvent mixture gives the bis-phenanthroline complex [Mn(phen)(2)(H2O)(2)] [Mn(O2C(CH2)(3)CO2) (phen)(2)H2O] (O2C(CH2)(3)CO2). 12H(2)O (3) which was characterised using X-ray crystallography. Complex 3 contains two independent mononuclear manganese(II) species, the dication [Mn(phen)(2)(H2O)(2)](2+) and the neutral manganese pentanedioate complex [Mn(O2C(CH2)(3)CO2) (phen)(2)(H2O)], along with a non-coordinated (O2C(CH2)(3)CO2)(2-) counter dianion. In the dication [Mn(phen)(2)(H2O)(2)](2+) the manganese atom is coordinated to four nitrogen atoms from two chelating phenanthroline ligands and two oxygen atoms from two cisoid water molecules. In the neutral fragment [Mn(O2C(CH2)(3)CO2) (phen)(2)(H2O)] the metal atom is coordinated to four nitrogen atoms from two chelating phenanthroline ligands, one oxygen atom from a unidentate (O2C(CH2)(3)CO2)(2-) ligand and one oxygen atom from a water molecule which is cis with respect to the coordinated carboxylate oxygen of the pentanedioate ligand. IR, magnetic and conductivity data for the complexes are given. All three complexes are catalysts for the disproportionation of H2O2 in the presence of added imidazole. (C) 1998 Elsevier Science S.A. All rights reserved.