Cyclic Voltammetry of Palladium(II) Complexes with Tridentate Arsine Ligands. Separation of the Two Single-Electron Transfer Steps of the Pd(II) 
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- 作者：Alison J. Downard ; Alan M. Bond ; Andrew J. Clayton ; Lyall R. Hanton ; and David A. McMorran
- 刊名：Inorganic Chemistry
- 出版年：1996
- 出版时间：December 18, 1996
- 年：1996
- 卷：35
- 期：26
- 页码：7684 - 7690
- 全文大小：230K
- 年卷期：v.35,no.26(December 18, 1996)
- ISSN：1520-510X
文摘
A detailed electrochemical study of the reduction of thefive-coordinate complexes[Pd(mtas)2]2+ and[Pd(ptas)2]2+(mtas = bis(2-(dimethylarsino)phenyl)methylarsine;ptas = bis(2-(dimethylarsino)phenyl)phenylarsine) hasbeenundertaken in acetonitrile and dichloromethane. When cyclicvoltammetry is carried out in acetonitrile at roomtemperature using conventional scan rates, the main voltammetricfeature is a single apparently quasireversibletwo-electron reduction step. A small peak due to reduction of thePd(I) dimer[Pd2(L3)2]2+(L3 = mtas, ptas)formed in a follow-up reaction is also observed. At lowertemperatures and faster scan rates, splitting of thetwo-electron reduction and associated oxidation peak occurs, enablingthe thermodynamics and kinetics of theindividual one-electron steps to be examined. The intermediatemonomeric Pd(I) species are thermodynamicallyunstable with respect to disproportionation, but slow (relative to theexperimental time scale) electrode kineticsfor the Pd(I/0) couples and slow kinetics for thedisproportionation reaction enable separation of theresponsesfor the Pd(II/I) and Pd(I/0) couples. Indichloromethane, the Pd(I) complexes are thermodynamically stableoverpotential ranges of ca. 180 and 20 mV for[Pd(ptas)2]+ and[Pd(mtas)2]+, respectively.Examination of theelectrochemical data allows rationalization of the trends instabilities of the Pd(I) species.