Electrochemistry, Chemical Reactivity, and Time-Resolved Infrared Spectroscopy of Donor–Acceptor Systems [(Qx)Pt(papy)] (Q = Substituted o-Quinone or o
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- 作者：Naina Deibel ; David Schweinfurth ; Stephan Hohloch ; Milan Delor ; Igor V. Sazanovich ; Michael Towrie ; Julia A. Weinstein ; Biprajit Sarkar
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：January 21, 2014
- 年：2014
- 卷：53
- 期：2
- 页码：1021-1031
- 全文大小：571K
- ISSN：1520-510X
文摘
The donor鈥揳cceptor complex [(O,NQ2鈥?/sup>)Pt(pap0)] (1; pap = phenylazopyridine, O,NQ0 = 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone), which displays strong 蟺-bonding interactions and shows strong absorption in the near-IR region, has been investigated with respect to its redox-induced reactivity and electrochemical and excited-state properties. The one-electron-oxidized product [(O,NQ鈥⑩€?/sup>)Pt(pap0)](BF4) ([1]BF4) was chemically isolated. Single-crystal X-ray diffraction studies establish the iminosemiquinone form of O,NQ in [1]+. Simulation of the cyclic voltammograms of 1 recorded in the presence of PPh3 elucidates the mechanism and delivers relevant thermodynamic and kinetic parameters for the redox-induced reaction with PPh3. The thermodynamically stable product of this reaction, complex [(O,NQ鈥⑩€?/sup>) Pt(PPh3)2](PF6) ([2]PF6), was isolated and characterized by X-ray crystallography, electrochemistry, and electron paramagnetic resonance spectroscopy. Picosecond time-resolved infrared spectroscopic studies on complex 1b (one of the positional isomers of 1) and its analogue [(O,OQ2鈥?/sup>)Pt(pap0)] (3; O,OQ = 3,5-di-tert-butyl-o-benzoquinone) provided insight into the excited-state dynamics and revealed that the nature of the lowest excited state in the amidophenolate complex 1b is primarily diimine-ligand-based, while it is predominantly an interligand charge-transfer state in the case of 3. Density functional theory calculations on [1]n+ provided further insight into the nature of the frontier orbitals of various redox forms and vibrational mode assignments. We discuss the mechanistic details of the newly established redox-induced reactivity of 1 with electron donors and propose a mechanism for this process.
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