Single-molecule magnets: Novel Mn8 and Mn9 carboxylate clusters containing an unusual pentadentate ligand derived from pyridine-2,6-dimethanol

Abstract

The reactions of the MnIII3 and MnIIMnIII2 complexes [Mn3O(O2CEt)6(py)3] [CIO4] and [Mn3O(O2CEt)6(py)3] with pyridine-2,6-dimethanol (pdmH2) afford the mixed-valence MnII6MnIII2 octanuclear complex [Mn8O2(py)4(O2 CEt)8(L)2][CIO4]2 (1) and the MnII7MnIII2 enneanuclear complex [Mn9(O2CEt)12(pdm)(pdmH)2 (L)2] (2), respectively. Both compounds contain a novel pentadentate ligand, the dianion of (6-hydroxymethylpyridin-2-yl)-(6-hydroxymethylpyridin-2-ylmethoxy)-methanol (LH2), which is the hemiacetal formed in situ from the Mn-assisted oxidation of pdmH2. Complex 1 crystallizes in the monoclinic space group P21/n with the following cell parameters at -160 °C: a = 16.6942(5) Å, b = 13.8473(4) Å, c..