Synthetic, electrochemical and structural aspects of a series of ferrocene-containing dicarbonyl β-diketonato rhodium(I) complexes
2005; Elsevier BV; Volume: 358; Issue: 8 Linguagem: Inglês
10.1016/j.ica.2005.02.010
ISSN1873-3255
AutoresJeanet Conradie, T. Stanley Cameron, M.A.S. Aquino, Gert J. Lamprecht, Jannie C. Swarts,
Tópico(s)Metal complexes synthesis and properties
ResumoTreatment of [Rh(β-diketonato)(cod)] with CO resulted in better yields of [Rh(FcCOCHCOR)(CO)2] than by treating [Rh(Cl)(CO)2]2 with FcCOCH2COR, R = CF3 (Hfctfa), CH3 (Hfca), Ph (Hbfcm, Ph = phenyl) and Fc (Hdfcm, Fc = ferrocenyl). The single crystal structure of the fctfa rhodium(I) complex [C16H10F3FeO4Rh], monoclinic, C 2/c(15), a = 13.266(3) Å, b = 19.553(3) Å, c = 13.278(3) Å, β = 100.92(2)°, Z = 8 showed both rotational and translational displacement disorders for the CF3 group. An electrochemical study revealed that the formal reduction potential, E0′, for the electrochemically reversible one electron oxidation of the ferrocenyl group varied between 0.304 (for the fctfa complex) and 0.172 V (for the dfcm complex) versus Fc/Fc+ in a manner that could be directly traced to the group electronegativities, χR, of the R groups on the β-diketonato ligands, as well as to the pKa′ values of the free β-diketones. Anodic peak potentials, Epa,Rh, for the dominant cyclic voltammetry peak associated with rhodium(I) oxidation were between 0.718 (bfcm complex) and 1.022 V (dfcm complex) versus Fc/Fc+. Coulometric experiments implicated a second, much less pronounced anodic wave for the apparent two-electron RhI oxidation that overlaps with the ferrocenyl anodic wave and that the redox processes associated with these two RhI oxidation waves are in slow equilibrium with each other.
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