Gupta Parna, Butcher Ray J, Bhattacharya Samaresh
Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Kolkata 700 032, India.
Inorg Chem. 2003 Aug 25;42(17):5405-11. doi: 10.1021/ic0343713.
Reaction of 2-(arylazo)phenols (H(2)ap-R; R = OCH(3), CH(3), H, Cl, and NO(2)) with [Os(PPh(3))(2)(CO)(2)(HCOO)(2)] affords a family of organometallic complexes of osmium(II) of type [Os(PPh(3))(2)(CO)(ap-R)] where the 2-(arylazo)phenolate ligand is coordinated to the metal center as a tridentate C,N,O-donor. Structure of the [Os(PPh(3))(2)(CO)(ap-H)] complex has been determined by X-ray crystallography. All the [Os(PPh(3))(2)(CO)(ap-R)] complexes are diamagnetic and show characteristic (1)H NMR signals and intense MLCT transitions in the visible region. They also show emission in the visible region at ambient temperature. Cyclic voltammetry on the [Os(PPh(3))(2)(CO)(ap-R)] complexes shows a reversible Os(II)-Os(III) oxidation within 0.39-0.73 V vs SCE, followed by a reversible Os(III)-Os(IV) oxidation within 1.06-1.61 V vs SCE. Coulometric oxidation of the [Os(PPh(3))(2)(CO)(ap-R)] complexes generates the Os(III)(PPh(3))(2)(CO)(ap-R) complexes, which have been isolated as the hexafluorophosphate salts. The [Os(III)(PPh(3))(2)(CO)(ap-R)]PF(6) complexes are one-electron paramagnetic and show axial ESR spectra. In solution they behave as 1:1 electrolytes and show intense LMCT transitions in the visible region. The [Os(III)(PPh(3))(2)(CO)(ap-R)]PF(6) complexes have been observed to serve as mild one-electron oxidants in a nonaqueous medium.
2 -（芳基偶氮）苯酚（H₂ap - R；R = OCH₃、CH₃、H、Cl和NO₂）与[Os(PPh₃)₂(CO)₂(HCOO)₂]反应，得到了一系列锇（II）的有机金属配合物[Os(PPh₃)₂(CO)(ap - R)]，其中2 -（芳基偶氮）酚盐配体作为三齿C、N、O供体与金属中心配位。[Os(PPh₃)₂(CO)(ap - H)]配合物的结构已通过X射线晶体学确定。所有的[Os(PPh₃)₂(CO)(ap - R)]配合物都是抗磁性的，在可见区域显示出特征性的¹H NMR信号和强烈的MLCT跃迁。它们在室温下在可见区域也有发射。对[Os(PPh₃)₂(CO)(ap - R)]配合物进行循环伏安法研究表明，相对于饱和甘汞电极（SCE），在0.39 - 0.73 V范围内有可逆的Os(II) - Os(III)氧化，随后在1.06 - 1.61 V范围内有可逆的Os(III) - Os(IV)氧化。对[Os(PPh₃)₂(CO)(ap - R)]配合物进行库仑氧化生成了[Os(III)(PPh₃)₂(CO)(ap - R)]⁺配合物，这些配合物已被分离为六氟磷酸盐盐。[Os(III)(PPh₃)₂(CO)(ap - R)]PF₆配合物是单电子顺磁性的，并显示出轴向电子自旋共振（ESR）光谱。在溶液中，它们表现为1:1电解质，并在可见区域显示出强烈的配体到金属中心的电荷转移（LMCT）跃迁。已观察到[Os(III)(PPh₃)₂(CO)(ap - R)]PF₆配合物在非水介质中可作为温和的单电子氧化剂。
