Structural Distortions upon Oxidation in Heteroleptic [Cp₂W(dmit)] Tungsten Dithiolene Complex: Combined Structural, Spectroscopic, and Magnetic Studies

Four different cation radical salts are obtained upon electrocrystallization of [Cp2W(dmit)] (dmit = 1,3-dithiole-2-thione-4,5-dithiolato) in the presence of the BF4−, PF6−, Br−, and [Au(CN)2]− anions. In these formally d1 cations, the WS2C2 metallacycle is folded along the S···S hinge to different extents in the four salts, an illustration of the noninnocent character of the dithiolate ligand. Structural characteristics and the charge distribution on atoms, for neutral and ionized complexes with various folding angles, were calculated using DFT methods, together with the normal vibrational modes and theoretical Raman spectra. Raman spectra of neutral complex [Cp2W(dmit)] and its salts formed with BF4−, AsF6−, PF6−, Br−, and [Au(CN)2]− anions were measured using the red excitation (λ = 632.8 nm). A correlation between the folding angle of the metallacycle and the Raman spectroscopic properties is analyzed. The bands attributed to the CC and C−S stretching modes shift toward higher and lower frequencies by about 0.3−0.4 cm−1 deg−1, respectively. The solid state structural and magnetic properties of the three salts are analyzed and compared with those of the corresponding molybdenum complexes. Temperature dependence of the magnetic susceptibility shows the presence of one-dimensional antiferromagnetic interactions in the BF4−, PF6−, and [Au(CN)2]− salts, while an antiferromagnetic ground state is identified in the Br− salt below TNéel = 7 K. Interactions are systematically weaker in the tungsten salts than in the isostructural molybdenum analogs, a consequence of the decreased spin density on the dithiolene ligand in the tungsten complexes.以[二(环戊二烯基)钨(dmit)]（dmit = 1,3-二硫杂环戊烯-2-硫酮-4,5-二硫醇根）为原料，在BF₄⁻、PF₆⁻、Br⁻及[Au(CN)₂]⁻阴离子存在下通过电结晶反应，可获得四种结构各异的阳离子自由基盐。在这些形式上为d¹的阳离子中，四种盐内的WS₂C₂金属杂环沿S···S铰链呈现出不同程度的折叠形变，这正是二硫代配体非无辜特性的直观佐证。针对不同折叠角度下的中性及离子化配合物，借助密度泛函理论（Density Functional Theory, DFT）方法完成了结构特征、原子电荷分布的计算，同时还对其正则振动模式与理论拉曼光谱进行了计算。采用波长632.8nm的红光激发，测定了中性配合物[二(环戊二烯基)钨(dmit)]及其与BF₄⁻、AsF₆⁻、PF₆⁻、Br⁻及[Au(CN)₂]⁻阴离子形成的盐的拉曼光谱。研究了金属杂环折叠角度与拉曼光谱特性之间的构谱关联：对应C=C与C-S伸缩振动的谱带分别以约0.3~0.4 cm⁻¹·deg⁻¹的速率向高频与低频方向偏移。对BF₄⁻、PF₆⁻及[Au(CN)₂]⁻三种盐的固态结构与磁学特性展开分析，并与对应钼系配合物进行对比。磁化率的温度依赖性测试显示，BF₄⁻、PF₆⁻及[Au(CN)₂]⁻盐体系中存在一维反铁磁相互作用；而Br⁻盐在奈尔温度（T_Néel=7K）以下则呈现反铁磁基态。钨系配合物的磁相互作用整体弱于同构钼系类似物，这源于钨配合物中二硫烯配体上的自旋密度有所降低。