1205548-87-3Relevant articles and documents
New bimetallic reactivity in Pt2II,III/Pt2 IV,IV transformation mediated by a benzene ring
Zhao, Shu-Bin,Cui, Qian,Wang, Suning
scheme or table, p. 998 - 1003 (2010/04/25)
A new Pt2 II,II complex with the formula Pt 2(TPAB)Me4 (1), where TPAB = 1,2,4,5-tetrakis(5-(/p-C 7H15Ph)-7-azaindol- l-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 Pt2 IV,IV species and the reverse reactions of the Pt2IV,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 1 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 [Pt2 IV,IV(TPAB)Me6][OTf]2 (6), while in the presence of O2, complex 7, Pt2IV,IV(TP AB)Me4(OTf)2, was obtained. Compound 1 was found to react readily with O2 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 PtIV centers in 6 are five-coordinate with a squarepyramidal 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), I2, and H2O2 to produce Pt2IV,IV(TPAB)Me4X2 (X = Cl, 2; Br, 3; I,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 Pt2IV,IV system. Complexes 2 and 7 can be reduced and converted back to complex 1 via reactions with BH4-, as established by NMR experiments.
