Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
Inorg Chem. 2010 Mar 15;49(6):2649-55. doi: 10.1021/ic9016195.
Reactions of dirhenium decacarbonyl with the two azoaromatic ligands, L(a) = (2-phenylazo)pyridine and L(b) = (4-chloro-2-phenylazo)pyridine (general abbreviation of the ligands is L) afford paramagnetic rhenium(II) complexes, [Re(II)(L(*-))(2)(CO)(2)] (1) (S = 1/2 ground state) with two one-electron reduced azo-anion radical ligands in an octahedral geometrical arrangement. At room temperature (300 K) the complexes 1a-b, showed magnetic moments (mu(eff)) close to 1.94 mu(B), which is suggestive of the existence of strong antiferromagnetic interactions in the complexes. The results of magnetic measurements on one of the complexes, 1b, in the temperature range 2-300 K are reported. The above complexes showed two cathodic and two anodic responses in cyclic voltammetry where one-electron oxidation leads to an unusual redox event involving simultaneous reduction of the rhenium(II) and oxidation of the second ligand via intramolecular electron transfer. The oxidized complexes 1a(+) and 1b(+) are air stable and were isolated as crystalline solids as their tri-iodide (I(3)(-)) salts. The structures of the two representative complexes, 1b and [1b]I(3), as determined by X-ray crystallography, are compared. The anionic complexes, 1 and 1 were characterized in solution by their spectral properties.
双羰基二铼与两种偶氮芳族配体，L(a)=(2-苯偶氮)吡啶和 L(b)=(4-氯-2-苯偶氮)吡啶（配体的通用缩写为 L）反应，得到顺磁性铼(II)配合物，[Re(II)(L(*-))(2)(CO)(2)]（1）（S = 1/2 基态），其中两个单电子还原的偶氮阴离子自由基配体呈八面体几何排列。在室温（300 K）下，配合物 1a-b 表现出接近 1.94 μB 的磁矩（μ(eff)），这表明在配合物中存在强烈的反铁磁相互作用。报道了其中一个配合物 1b 在 2-300 K 温度范围内的磁测量结果。上述配合物在循环伏安法中显示出两个阴极和两个阳极响应，其中单电子氧化导致异常的氧化还原事件，涉及铼(II)的同时还原和通过分子内电子转移氧化第二个配体。氧化的配合物 1a(+)和 1b(+)在空气中稳定，并作为其三碘化物（I(3)(-))盐分离为结晶固体。通过 X 射线晶体学确定了两个代表性配合物 1b 和 [1b]I(3)的结构，并进行了比较。通过其光谱性质在溶液中对阴离子配合物1和1进行了表征。
