EPR spectroscopic characterization of a monomeric ptᴵᴵᴵ species produced via electrochemical oxidation of the anticancer compound trans-[Ptᴵᴵ{(p-HC₆F₄)NCH₂CH₂NEt₂}Cl(py)]
Journal Publication ResearchOnline@JCUAbstract
The bulk oxidative electrolysis of a 2 mM solution of trans-[Pt-II{(p-HC6F4)NCH2CH2NEt2)Cl(py)] in highly non coordinating dichloromethane (0.05 M [Bu4N][B(C6F5)]) media leads to the formation of about 14% of the Pt-III species trans-[pt(III){(p-HC6F4)NCH2CH2NEt2}Cl(py)](+). The EPR spectrum of this electro-synthesized formally Pt-III species shows Pt-hyperfine coupling with g(x) similar to g(y) > g(z) similar to g(e), and is broadly consistent with the simple crystal field theory prediction for 5d(7) Pt-III in an elongated tetragonal environment where the unpaired electron is in a 5d(z(2)) orbital. The crystal field calculations lead to an estimate of the 5d(z(2)) 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-[pt(II){(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.
Journal
Journal of Inorganic Biochemistry
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Volume
162
ISBN/ISSN
0162-0134
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Pages Count
7
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Elsevier
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DOI
10.1016/j.jinorgbio.2016.01.015