Harden Nicholas C, Bolcar Milissa A, Wernsdorfer Wolfgang, Abboud Khalil A, Streib William E, Christou George
Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA.
Inorg Chem. 2003 Nov 3;42(22):7067-76. doi: 10.1021/ic0348906.
The synthesis and magnetic properties are reported of two new clusters Mn(10)O(4)(OH)(2)(O(2)CMe)(8)(hmp)(8)(4) (1) and Mn(7)(OH)(3)(hmp)(9)Cl(3)(ClO(4)) (2). Complex 1 was prepared by treatment of Mn(3)O(O(2)CMe)(6)(py)(3) with 2-(hydroxymethyl)pyridine (hmpH) in CH(2)Cl(2), whereas 2 was obtained from the reaction of MnCl(2).4H(2)O, hmpH, and NBu(n)(4)MnO(4) in MeCN followed by recrystallization in the presence of NBu(n)(4)ClO(4). Complex 1.2py.10CH(2)Cl(2).2H(2)O crystallizes in the triclinic space group P1. The cation consists of 10 Mn(III) ions, 8 mu(3)-O(2)(-) 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).H(2)O crystallizes in the triclinic space group P1. 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 (DS(z)(2)), 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.
报道了两个新的簇合物Mn(10)O(4)(OH)(2)(O(2)CMe)(8)(hmp)(8)(4) (1)和Mn(7)(OH)(3)(hmp)(9)Cl(3)(ClO(4)) (2)的合成及磁性。配合物1是通过在二氯甲烷中用2-(羟甲基)吡啶(hmpH)处理Mn(3)O(O(2)CMe)(6)(py)(3)制备的，而配合物2是由氯化锰·4水合物、hmpH和正丁基铵四氧化锰在乙腈中反应，然后在正丁基铵高氯酸盐存在下重结晶得到的。配合物1·2py·10CH(2)Cl(2)·2H(2)O结晶于三斜空间群P1。阳离子由10个Mn(III)离子、8个μ(3)-O(2)(-)离子、2个μ(3)-OH(-)离子、8个桥连乙酸根和8个桥连及螯合的hmp(-)配体组成。hmp(-)配体通过其O原子以两种方式桥连：两个与μ(3)-O原子相连，六个与μ(2)-O原子相连。配合物2·3CH(2)Cl(2)·H(2)O结晶于三斜空间群P1。阳离子由四个Mn(II)和三个Mn(III)离子组成，排列成一个由交替的Mn(II)和Mn(III)离子构成的Mn(6)六边形，围绕着一个中心Mn(II)离子。其余的配位是由三个μ(3)-OH(-)离子、三个端基氯离子和九个桥连及螯合的hmp(-)配体提供的。六个hmp(-)配体含有μ(2)-O原子，三个含有μ(3)-O原子。Cl(-)阴离子与三个μ(3)-OH(-)离子形成氢键。在5.00 - 300 K范围内，在5 kG的外加磁场中收集了配合物1的变温直流(dc)磁化率数据。χ(M)T值从300 K时的17.87 cm(3) mol(-1) K逐渐降至5.00 K时的1.14 cm(3) mol(-1) K，表明基态为S = 0。配合物2的基态自旋通过在0.5 - 3.0 T和1.80 - 4.00 K范围内的磁化测量确定。仅考虑轴向各向异性(DS(z)(2))，通过矩阵对角化对数据进行拟合，得到S = 10、g = 2.13、D = -0.14 cm(-1)和S = 11、g = 1.94、D = -0.11 cm(-1)时拟合效果同样良好。磁化强度与直流磁场扫描至0.04 K时，未发现归因于单分子磁性行为的磁滞现象，仅存在弱的分子间相互作用。
