Manganese(II) complexes of hexanedioic and heptanedioic acids: X-ray crystal structures of [Mn(O2C(CH2)4CO2(phen)2H2O] · 7H2O and [Mn(phen)2(H2O)2][Mn(O2C(CH2)5CO2) [phen)2H2O](O2C(CH2)5CO2) · 12.5H2O