title: EPR spectroscopic characterization of a monomeric PtIIIspecies produced via electrochemical oxidation of the anticancer compound trans-[PtII{(p-HC6F4)NCH2CH2NEt2}Cl(py)].
abstract: The bulk oxidative electrolysis of a 2mM solution of trans-[PtII{(p-HC6F4)NCH2CH2NEt2}Cl(py)] in highly non-coordinating dichloromethane (0.05M [Bu4N][B(C6F5)]) media leads to the formation of about 14% of the PtIIIspecies trans-[PtIII{(p-HC6F4)NCH2CH2NEt2}Cl(py)]+. The EPR spectrum of this electro-synthesized formally PtIIIspecies shows Pt-hyperfine coupling with gx~gy>gz~ge, and is broadly consistent with the simple crystal field theory prediction for 5d7PtIIIin an elongated tetragonal environment where the unpaired electron is in a 5d(z2) orbital. The crystal field calculations lead to an estimate of the 5d(z2) character of around 37% and indicate partial delocalization of the unpaired electron onto the orbitals of the surrounding ligands. Transient cyclic voltammetric and steady-state microelectrode studies in the same media as used for bulk electrolysis exhibit a chemically reversible one electron oxidation process under their shorter time scale conditions. Analysis of X-ray diffraction data obtained from a single crystal of trans-[PtII{(p-HC6F4)NCH2CH2NEt2}Cl(py)] shows the square planar geometry of the ligands around the Pt metal center and the 'W' arrangement of the ethyl groups on the ligand is explained in terms of agostic interactions.
authors.affiliation: School of Chemistry, Monash University, Clayton, 3800, VIC, Australia.
authors.forename: Ruchika
authors.initials: R
authors.lastname: Ojha
authors.affiliation: School of Physics, Monash University, Clayton, 3800, VIC, Australia.
authors.forename: John F
authors.initials: JF
authors.lastname: Boas
authors.affiliation: School of Chemistry, Monash University, Clayton, 3800, VIC, Australia. Electronic address: glen.deacon@monash.edu.
authors.forename: Glen B
authors.initials: GB
authors.lastname: Deacon
authors.affiliation: College of Science, Technology & Engineering, James Cook University, Townsville, QLD 4811, Australia. Electronic address: peter.junk@jcu.edu.au.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Junk
authors.affiliation: School of Chemistry, Monash University, Clayton, 3800, VIC, Australia. Electronic address: alan.bond@monash.edu.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Bond
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004572:Electrolysis; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D005459:Fluorides / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D008024:Ligands; D011725:Pyridines; D010984:Platinum; D005459:Fluorides
keywords: Anticancer agents; EPR spectroscopy; Electrochemical generation of monomeric Pt(III) species