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摘要
A new Pt-2(II,II) complex with the formula Pt-2(TPAB)Me-4 (1), where TPAB = 1,2,4,5-tetrakis(5-(p-C tau-H15Ph)-7-azaindol-1-yl)benzene, has been synthesized. This molecule has excellent solubility in common solvents, which enabled our investigation of its reactions with a variety of oxidants to form Pt-2(IV,IV) species and the reverse reactions of the Pt-2(IV,IV) species back to 1 via reduction. Despite the lack of direct Pt...Pt interactions, the two Pt centers in 1 display distinct bimetallic cooperativity mediated by the central phenyl ring of the TPAB ligand. The most unusual Finding is that the reactivity of I with MeOTf is highly dependent on the amount of molecular oxygen present in the reaction medium. In the absence of O-2, the reaction of 1 with MeOTf produced [Pt-2(IV,IV)(TPAB)Me-6][OTf](2) (6), while in the presence of O-2, complex 7, Pt-2(IV,IV)(TPAB)Me-4(OTf)(2), was obtained. Compound 1 was found to react readily with O-2 at one atmosphere and ambient temperature to produce an insoluble and not yet fully characterized solid that further reacts with MeOTf to produce 7 quantitatively. NMR and single-crystal X-ray diffraction analyses established that the two Pt-IV centers in 6 are five-coordinate with a square-pyramidal geometry, while in 7 the two Pt-IV centers are six-coordinate with an octahedral geometry. Most significantly, the central phenyl ring of the TPAB ligand was transformed to a cyclohexyldienyl in 7, while it remains unchanged in 6. Complex 1 also reacts readily with other oxidants such as CHCl3, PhICl2, Br-2 (CBr4), I-2, and H2O2 to produce Pt-2(IV,IV)(TPAB)Me4X2 (X = Cl, 2; Br, 3; 1, 4; OH, 5). The structures of 2-5 are similar to that of 7, showing the generality of the central phenyl ring mediated oxidation of the Pt-2(II,II) system. Complexes 2 and 7 call be reduced and converted back to complex 1 via reactions with BH4-, its established by NMR experiments.
- 出版日期2010-2-22
