title: Reversibly reducible cis-dichloroplatinum(II) and cis-dichloropalladium(II) complexes of bis(1-methylimidazol-2-yl)glyoxal.
abstract: Complexes cis-MCl2(big), big=bis(1-methylimidazol-2-yl)glyoxal, M=Pt, Pd, were prepared and characterized through electrochemistry, spectroscopy, and for M=Pt, by X-ray structure analysis. The seven-membered chelate ring formed through N,N' coordination of the ligand big shows a boat conformation in agreement with density functional theory (DFT) calculation results. No significant intermolecular interactions were observed for the platinum compound. Both the PdII and PtII complexes undergo reversible one-electron reduction in CH2Cl2/ 0.1 M Bu4NPF6; the reduced palladium compound disintegrates above -30 degrees C. Electron paramagnetic resonance (EPR), UV-vis, and IR spectroelectrochemistry studies were employed to study the monoanions. The anion radical complex [cis-PtCl2(big)]*- exhibits a well-resolved EPR spectrum with small but well-detectable g anisotropy and an isotropic 195Pt hyperfine coupling of 12.2 G. DFT calculations confirm the spin concentration in the alpha-semidione part of the radical complex with small delocalization to the bis(imidazolyl)metal section. The results show that EPR and electroactive moieties can be linked to the cis-dichloroplatinum(II) group via imidazole coordination.
authors.affiliation: Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.
authors.forename: Ece
authors.initials: E
authors.lastname: Bulak
authors.forename: Markus
authors.initials: M
authors.lastname: Leboschka
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schwederski
authors.forename: Orkan
authors.initials: O
authors.lastname: Sarper
authors.forename: Tereza
authors.initials: T
authors.lastname: Varnali
authors.forename: Jan
authors.initials: J
authors.lastname: Fiedler
authors.forename: Falk
authors.initials: F
authors.lastname: Lissner
authors.forename: Thomas
authors.initials: T
authors.lastname: Schleid
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006037:Glyoxal / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009944:Organoplatinum Compounds / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D009944:Organoplatinum Compounds; D006037:Glyoxal