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Article Citation - WoS: 1Electrochemistry of Acetate-, Carbonate-, Sulfate-, and Dihydrogenphosphate-Bridged Dirhodium(ii) Complexes(verlag Z Naturforsch, 2003) Yaman, SO; Önal, AM; Isci, HComplexes, [Rh-2(B-B)(4)L-2](n) (B-B = CH3CO2-, L = CH3CN, H2O, Cl-, Br-, SCN-; B-B CO32-, SO42-, H2PO4-, L = H2O, Cl-, Br-, SCN-) were prepared and their cyclic voltammograms (CV) and electronic absorption spectra were measured in solution. The CV of the complexes exhibits a reversible one-electron transfer from a metal-based orbital. Constant potential electrolysis at the oxidation peak potential of [Rh-2(O2CCH3)(4)(NCCH3)(2)] in acetonitrile yielded [Rh-2(O2CCH3)(4)(NCCH3)(2)](+), a mixed valent Rh(II)-Rh(III) cation complex. The formation of the mixed valent complex was monitored by measuring electronic absorption spectra of the solution in situ during the oxidative electrolysis. The reductive electrolysis of the mixed valent complex solution, in the same electrolysis cell, yielded the original electronic absorption spectrum of the starting complex. The changes in the oxidation and reduction potentials of the complexes with different axial ligands, L = H2O, Cl-, Br-, SCN-, are correlated to the relative energy changes of HOMO and LUMO of the complexes, which indicates the metal-axial ligand sigma- and pi-bonding interactions. Spectroscopic and CV data indicate that the degree of a-interaction is Cl- > Br- > SCN-, and that of pi-interaction is Br- > SCN- > Cl-.Article Citation - WoS: 13Electrochemical and Quantum Chemical Studies on Mitomycin and Adriamycin(Elsevier, 2003) Özalp-Yaman, S; Önal, AM; Türker, LIn-situ spectroelectrochemical redox behaviour of two prominent chemotherapeutic agents, mitomycin and adriamycin were studied at constant potential. AM 1 (UHF) type quantum chemical calculations on the neutral as well as radical anion and cation forms of mitomycin and adriamycin were performed. (C) 2003 Elsevier Science B.V. All rights reserved.Article Citation - WoS: 14Citation - Scopus: 19Electrochemistry of nickel(II) complexes with N,N'-bis(3,5-di-tert-butylsalicylidene)polymethylenediamines(Pergamon-elsevier Science Ltd, 2005) Özalp-Yaman, S; Kasumov, VT; Önal, AMThe electrochemical oxidation of several N,N'-polymethylenebis(3,5-di-tert- butylsalicylaldiminato)nickel(II) complexes, Ni(L-x), has been studied by cyclic voltammetry and in situ UV-Vis spectroscopy in DMF Cyclic voltammograms of Ni(L-x) (x = 1-4) complexes displayed two-step oxidation processes under nitrogen gas atmosphere. The first oxidation peak potentials of all the Ni(II) complexes corresponds to the reversible one-electron oxidation process of the metal center, yielding Ni(III) species. EPR spectrum of the electrolysis solution was recorded after one electron transfer at liquid nitrogen temperature also confirms the formation of [Ni-III (L-3)](+) species (g(x) > g(y) > g(z)) with a (2)A(1)(d(z)(2))(1) ground state. Upon addition of pyridine to one electron oxidised solutions a new penta coordinated species, [Ni-III(L-3)Py](+) (g(perpendicular to) > g(parallel to), a(parallel to)(N-14) = 8 G), was produced. The second oxidation peak of the complexes was assigned as the ligand based oxidation, generating a coordinated phenoxy radical species. (c) 2005 Elsevier Ltd. All rights reserved.
