混合价四核锰配合物[Mn4O2(ClCH2COO)7(bipy)2]•H2O的合成、晶体结构及性质研究

在乙腈溶液中, 由混合价三核锰配合物Mn₃O(ClCH₂COO)₆(py)₂]•(H₂O) (py为吡啶)与2,2′-联吡啶(bipy)反应合成了混合价(Mn₃^IIIMn^II)四核锰配合物Mn₄O₂(ClCH₂COO)₇(bipy)₂]•H₂O. 采用元素分析、红外光谱、热分析和X射线单晶衍射法确定了其组成和结构. 标题化合物晶体属于三斜晶系, 空间群P-1, 晶胞参数: a＝0.89854(13) nm, b＝1.4027(2) nm, c＝1.9037(3) nm, α＝93.518(3)°, β＝96.736(3)°, γ＝94.875(3)°, V＝2.3680(6) nm³, Z＝2, D_c＝1.734 g/cm³, F(000)＝1238, GOF＝1.036, R₁＝0.0592, wR₂＝0.1162 I＞2σ(I)]. 在标题化合物中, 配位结构单元中心为一蝶型Mn₄(μ₃-O)₂]^7＋多核簇, 含有2个Mn₃(μ₃-O)单元, 具有近似C₂对称轴. 4个Mn离子均为六配位, 外围配体为7个氯乙酸根和2个2,2′-联吡啶, 处于变形的八面体环境. 变温磁化率研究表明标题化合物在整体上表现为反铁磁性耦合作用, 但在低温下的磁相互作用较为复杂.

Synthesis, Structure and Properties of Mixed-Valence Tetranuclear Manganese Complex [Mn4O2(ClCH2COO)7(bipy)2]•H2O

The reaction of trinuclear manganese complex Mn₃O(ClCH₂COO)₆(py)₂]•(H₂O) with 2,2′-bipyridine in CH₃CN led to the new mixed valence tetranuclear Mn₃^IIIMn^II complex of formulation Mn₄O₂(ClCH₂COO)₇(bipy)₂]•H₂O. The structure and chemical composition of title complex were determined by elemental analysis, IR spectrum, thermal analysis and X-ray diffraction analysis. The crystal structure belongs to triclinic system with space group P-1 and a＝0.89854(13) nm, b＝1.4027(2) nm, c＝1.9037(3) nm, α＝93.518(3)°, β＝96.736(3)°, γ＝94.875(3)°, V＝2.3680(6) nm³, Z＝2, D_c＝1.734 g/cm³, F(000)＝1238, GOF＝1.036, R₁＝0.0592, wR₂＝0.1162 I＞2σ(I)]. The analysis of the crystal structure indicates that the title complex has a butterfly Mn₄(μ₃-O)₂]^7＋core, which consists of two Mn₃(μ₃-O) units, with approximate C₂ symmetric axis. The four manganese atoms are all six-coordinated with seven chloroacetate acid anions and two 2,2′-bipyridine molecules, forming distorted octahedron configuration. Variable temperature magnetic susceptibility of the title complex showed the existence of intramolecular antiferromagnetic interaction, and it was intricate at relatively low temperature.