Heptanuclear and decanuclear manganese complexes with the anion of 2-hydroxymethylpyridine

The synthesis and magnetic properties are reported of two new clusters [Mn10O4(OH)(2)(O2CMe)(8)(hmp)(8)](ClO4)(4) (1) and [Mn-7(OH)(3)(hmp)(9)Cl-3](Cl)(ClO4) (2). Complex 1 was prepared by treatment of [Mn3O(O2CMe)(6)(py)(3)](ClO4) with 2-(hydroxymethyl)pyridine (hmpH) in CH2Cl2, whereas 2 was obtained from the reaction of MnCl2.4H(2)O, hmpH, and (NBu4MnO4)-Mn-n in MeCN followed by recrystallization in the presence of (NBu4ClO4)-Cl-n. Complex 1.2py.10CH(2)Cl(2).2H(2)O crystallizes in the triclinic space group P (1) over bar. The cation consists of 10 Mn-III ions, 8 mu(3)-O2- ions, 2 mu(3)-OH- ions, 8 bridging acetates, and 8 bridging and chelating hmp(-) ligands. The hmp(-) ligands bridge through their O atoms in two ways: two with mu(3)-O atoms and six with mu(2)-O atoms. Complex 2.3CH(2)Cl(2).H2O crystallizes in the triclinic space group P (1) over bar. The cation consists of four Mn-II and three Mn-III ions, arranged as a Mn-6 hexagon of alternating Mn-II and Mn-III ions surrounding a central Mn-II ion. The remaining ligation is by three mu(3)-OH- ions, three terminal chloride ions, and nine bridging and chelating hmp- ligands. Six hmp- ligands contain mu(2)-O atoms and three contain mu(3)-O atoms. The Cl- anion is hydrogen-bonded to the three mu(3)-OH- ions. Variable-temperature direct current (dc) magnetic susceptibility data were collected for complex 1 in the 5.00-300 K range in a 5 kG applied field. The chi(M)T value gradually decreases from 17.87 cm(3) mol(-1) K at 300 K to 1.14 cm(3) mol(-1) K at 5.00 K, indicating an S = 0 ground state. The ground-state spin of complex 2 was established by magnetization measurements in the 0.5-3.0 T and 1.80-4.00 K ranges. Fitting of the data by matrix diagonalization, incorporating only axial anisotropy (D (S) over cap (2)(z)), gave equally good fits with S = 10, g = 2.13, D = -0.14 cm(-1) and S = 11, g = 1.94, D = -0.11 cm(-1). magnetization versus dc field scans down to 0.04 K reveal no hysteresis attributable to single-molecule magnetism behavior, only weak intermolecular interactions.