Rhodium Assisted C-H Activation of Benzaldehyde Thiosemicarbazones and Their Oxidation via Activation of Molecular Oxygen

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• 作者：Rama Acharyya ; Swati Dutta ; Falguni Basuli ; Shie-Ming Peng ; Gene-Hsiang Lee ; Larry R. Falvello ; and Samaresh Bhattacharya
• 刊名：Inorganic Chemistry
• 出版年：2006
• 出版时间：February 6, 2006
• 年：2006
• 卷：45
• 期：3
• 页码：1252 - 1259
• 全文大小：168K
• 年卷期：v.45,no.3(February 6, 2006)
• ISSN：1520-510X

文摘

The benzaldehyde thiosemicarbazones are found to undergo oxidation at the sulfur center upon reaction with[Rh(PPh₃)₃Cl] in refluxing ethanol in the presence of a base (NEt₃). A group of organorhodium complexes areobtained from such reactions, in which the oxidized thiosemicarbazones are coordinated to rhodium as tridentateCNS donors, along with two triphenylphosphines and a hydride. From the reaction with para-nitrobenzaldehydethiosemicarbazone, a second organometallic complex is obtained, in which the thiosemicarbazone is coordinatedto rhodium as a tridentate CNS donor, along with two triphenylphosphines and a hydride. Reaction of the benzaldehydethiosemicarbazones with [Rh(PPh₃)₃Cl] in refluxing ethanol in the absence of NEt₃ affords another group oforganorhodium complexes, in which the thiosemicarbazones are coordinated to rhodium as tridentate CNS donors,along with two triphenylphosphines and a chloride. Structures of representative complexes of each type of complexeshave been determined by X-ray crystallography. In all of the complexes, the two PPh₃ ligands are trans. All of thecomplexes show intense MLCT transitions in the visible region. Cyclic voltammetry on these complexes shows aRh(III)-Rh(IV) oxidation on the positive side of SCE. Redox responses of the coordinated thiosemicarbazones arealso displayed by all of the complexes.