Abstract
An acyclic hexadentate diimine ligand, H4L1, was prepared in situ in methanol by the condensation of 1,4-diformyl-2,3-dihydroxybenzene (1) with 2-aminoethanol, and complexed directly with two equivalents of Mn-II(OAc)(2)center dot 4H(2)O or Mn-III(OAc)(3)center dot 2H(2)O, or with one equivalent of each. All three of these one-pot reactions gave the mixed-valent tetrametallic complex [(Mn2Mn2III)-Mn-II(L-1)(2)(OAc)(2)(solvents)(4)], [2(solvents)(4)]. An X- ray crystal structure determination on [2(MeOH)(4)]center dot 2MeOH revealed a centre of inversion in the middle of the complex. The four metal ions are in an almost planar array, sandwiched by two offset ligands which provide all of the equatorial donors, with the axial sites occupied by acetate ions and methanol molecules. The two manganese(II) ions are seven coordinate and centrally located, whereas the two manganese(III) ions are Jahn-Teller elongated octahedra and are located in the outer sites. Magnetic analysis of an air-dried sample, [2(MeOH)(2)(H2O)(2)]center dot 3H(2)O, showed that weak antiferromagnetic interactions between the manganese ions dominate, resulting in a low ground spin state.