Polynuclear osmium-dioxolene complexes: comparison of electrochemical and spectroelectrochemical properties with those of their ruthenium analogues
Polynuclear osmium-dioxolene complexes: comparison of electrochemical and spectroelectrochemical properties with those of their ruthenium analogues
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DOI：
10.1039/b004858p
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发表时间：
2000-01-01
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影响因子：
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通讯作者：
Ward, MD
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作者：
Barthram, AM;Reeves, ZR;Ward, MD
[Os（bipy）（2）Cl-2]的反应（bipy= 2，2 ′-bipyridine）与聚二氧杂环戊烯配体3，4，3 ′，4 ′-四羟基联苯（H4 L1）、2，3，6，7-三羟基-9-苯基咕吨-3-酮（H3 L2）或2，3，6，7，10，11-六羟基苯并菲（H6 L3）反应，得到配合物[{Os（bipy）（2）}（2）（μ-L-1）][PF 6]（2），[{Os（bipy）（2）}（2）（mu-L-2）][PF 6]（3）和三核配合物[{Os（bipy）（2）}（3）（mu-L-3）][PF 6]（3）分别简称为[Os-2（L-1）]（2+）、[Os-2（L-2）]（3+）和[Os-2（L-3）]（3+）。在这些配合物中，两个或三个{Os-III（bipy）（2）（OO）}片段通过共轭桥连配体连接（其中OO表示任何氧化态的二氧戊环结合位点）。配合物表现出丰富的电化学行为，显示金属为中心的Os-III-Os-II夫妇（作为还原）和配体为中心的夫妇（作为氧化）的组合。UV/维斯/NIR光谱电化学分析在所有可接近的氧化态下对所有三种络合物进行，并且参考单核模型络合物[Os-III（bipy）（2）（cat）][PF 6]（H（2）cat=邻苯二酚）对光谱电化学进行了检查，并且对其进行了晶体学表征。与先前描述的钌类似物的比较是有趣的，由于它们不同的内部氧化态分布。而单核配合物[Os-III（bipy）（2）（cat）]（+）含有与儿茶酚盐配位的Os-III（氧化金属，还原配体），处于相同氧化态的钌类似物是[Ru-II（bipy）（2）（sq）]（+）（sq= 1，2-苯并半醌单阴离子），即还原金属和氧化配体。同样的行为模式持续在双核和三核配合物，并导致有趣的差异，在电化学性能的钌和锇同系物。
Reaction of [Os(bipy)(2)Cl-2] (bipy=2,2'-bipyridine) with the poly-dioxolene ligands 3,4,3',4'-tetrahydroxybiphenyl (H4L1), 2,3,6,7-trihydroxy-9-phenylxanthen-3-one (H3L2) or 2,3,6,7,10,11-hexahydroxytriphenylene (H6L3) afforded the complexes [{Os(bipy)(2)}(2)(mu-L-1)][PF6](2), [{Os(bipy)(2)}(2)(mu-L-2)][PF6](3), and the trinuclear complex [{Os(bipy)(2)}(3)(mu-L-3)][PF6](3) abbreviated as [Os-2(L-1)](2+), [Os-2(L-2)](3+) and [Os-2(L-3)](3+), respectively. In these complexes two or three {Os-III(bipy)(2)(OO)} fragments are linked by the conjugated bridging ligands (where OO denotes a dioxolene binding site in any oxidation state). The complexes exhibit rich electrochemical behaviour, displaying a combination of metal-centred Os-III-Os-II couples (as reductions) and ligand-centred couples (as oxidations). UV/VIS/NIR spectroelectrochemical analysis was carried out on all three complexes in all accessible oxidation states, and the spectra were assigned with reference to the mononuclear model complex [Os-III(bipy)(2)(cat)][PF6] (H(2)cat=catechol) which was also examined spectroelectrochemically, as well as being crystallographically characterised. The comparison with the previously described ruthenium analogues is interesting due to their different internal oxidation state distribution. Whereas the mononuclear complex [Os-III(bipy)(2)(cat)](+) contains Os-III co-ordinated to a catecholate (oxidised metal, reduced ligand), the ruthenium analogue in the same oxidation state is [Ru-II(bipy)(2)(sq)](+) (sq=1,2-benzosemiquinone monoanion), i.e. reduced metal and oxidised ligand. The same pattern of behaviour persists in the dinuclear and trinuclear complexes, and leads to interesting differences in the electrochemical properties of the ruthenium and osmium congeners.