Electron Delocalization in Spectroelectrochemically and Computationally Characterized [Pt{(-BrCF)NCH═C(Cl)NEt}Cl(py)] Formed by Electrochemical Oxidation of [Pt{(-BrCF)NCH═C(Cl)NEt}Cl(py)].

[Pt{(-BrCF)NCH═C(Cl)NEt}Cl(py)] () is the product of the hydrogen peroxide oxidation of the Pt anticancer agent [Pt{(-BrCF)NCHCHNEt}Cl(py)] (). Insights into electron delocalization and bonding in [Pt{(-BrCF)NCH═C(Cl)NEt}Cl(py)] () obtained by electrochemical oxidation of have been gained by spectroscopic and computational studies. The process is chemically and electrochemically reversible on the short time scale of voltammetry in dichloromethane (0.10 M [BuN][PF]). Substantial stability is retained on longer time scales enabling a high yield of to be generated by bulk electrolysis. IR and visible spectroelectrochemical studies on the oxidation of to and the reduction of back to confirm the long-term chemical reversibility. DFT calculations indicate only a minor contribution to the electron density (13%) resides on the Pt metal center in , indicating that the oxidation process is extensively ligand-based. Published X-ray crystallographic data show that is present in only one structural form, while NMR data on the dissolved crystals revealed the presence of two closely related structural forms in an almost equimolar ratio. Solution-phase EPR spectra of are consistent with two closely related structural forms in a ratio of about 90:10. The average value for the frozen solution spectra (2.0567 for the major species) is significantly greater than the 2.0023 expected for a free radical. Crystal field analysis of the EPR spectra leads to an estimate of the 5d() character of around 10% in . Analysis of X-ray absorption fine structure derived from also supports the presence of a delocalized singly occupied metal molecular orbital with a spin density of approximately 17% on Pt. Accordingly, the considerably larger electron density distribution on the ligand framework (diminished Pt character) is proposed to contribute to the increased stability of compared to that of .