Mn(CH3CO2)(2) . 4H(2)O reacts with ethanolic solutions of hexanedioic and heptanedioic acids (ca 1:1 mol ratio) to produce the respective manganese(II) complexes [Mn(O2C(CH2)(4)CO2)H2O] (1) and [Mn(O2C(CH2)(5)CO2)] (2). Subsequent reaction of 1 and 2 with 1,10-phenanthroline (phen) (ca 1:2 mol ratio) in aqueous ethanol gives [Mn(O2C(CH2)(4)CO2)(phen)(2)H2O]. 7H(2)O (3) and [Mn(phen)(2)(H2O)(2)][Mn(O2C(CH2)(5)CO2 (phen)(2)H2O](O2C(CH2)(5)CO2). 12.5H(2)O (4), respectively. Complexes 3 and 4 have been structurally characterised. The asymmetric unit in 3 has a manganese(II) atom coordinated to four nitrogen atoms from two chelating phenanthroline ligands, one oxygen atom from a unidentate (O2C(CH2)(4)CO2)(-2) ligand and one oxygen atom from a water molecule which is in a cisoid position with respect to the diacid ligand. The asymmetric unit in 4 contains two mononuclear manganese(II) species, the dication [Mn(phen)(2)(H2O)(2)](2+) and the neutral manganese heptanedioate complex [Mn(O-2(CH2)(5)CO2)(phen)(H2O)], along with a non-coordinated (O2C(CH2)(5)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)(5)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)(5)CO2)(2-) ligand and one oxygen atom from a water molecule which is cis with respect to the coordinated carboxylate oxygen of the heptanedioate ligand. IR, magnetic and conductivity data for the complexes are given. All four complexes are catalysts for the disproportionation of H2O2 in the presence of added imidazole. (C) 1997 Elsevier Science Ltd.