12267-22-0Relevant academic research and scientific papers
Electrochemical and density functional theory study of bis(cyclopentadienyl) mono(β-diketonato) titanium(IV) cationic complexes
Kuhn, Annemarie,Conradie, Jeanet
, p. 257 - 264 (2010)
The electrochemical behaviour of fluorinated bis(cyclopentadienyl) mono(β-diketonato) titanium(IV) complexes, of general formula [Cp 2Ti(R′COCHCOR)]+ClO4- with Cp = cyclopentadienyl and R′, R = CF3, C4H 3S; CF3, C4H3O; CF3, Ph (C6H5); CF3, CH3; CH3, CH3; Ph, Ph and Ph, CH3 is described. Both metal and ligand based redox processes are observed. The chemically and electrochemically reversible TiIV/TiIII couple is followed by an irreversible ligand reduction at a considerably more negative (cathodic) potential. A comparison of the ligand reduction in its free and chelated state indicates that the β-diketonato ligand (R′COCHCOR)- in [Cp2Ti(R′COCHCOR)]+ClO4- is electroactive at more negative potentials. A theoretical density functional theory (DFT) study shows that a highly localized metal centred frontier orbital dominates the TiIV/TiIII redox chemistry resulting in a non-linear relationship between the formal redox potential (E°′) and the sum of the group electronegativities of the R and R′ groups, χR + χR′, of the ligand. Linear relationships, however, are obtained between the DFT calculated electron affinity (EA) of the complexes and χR + χR′, the pKa of the free β-diketones R′COCH2COR and the carbonyl stretching frequency, vCO, of the complexes. The DFT calculated electronic structure of the second reduced species [Cp 2Ti(β-diketonato)]- shows that it is best described as Ti(III) coupled to a β-diketonato radical.
Synthesis, crystal structure and electrochemistry of tetrahedral mono-β-diketonato titanocenyl complexes
Erasmus, Elizabeth,Conradie, Jeanet,Muller, Alfred,Swarts, Jannie C.
, p. 2277 - 2283 (2007)
The synthesis of a variety of tetrahedral β-diketonato titanium(IV) complexes of the type [(C5 H5)2 Ti (CH3 COCHCOR)]+ ClO4- with R = CF3, OCH3, C6H5, CH3 and Fc is described. The TiIII/TiIV couples and the Fc/Fc+ couple exhibited chemically and electrochemically reversible cyclic voltammetric behaviour. The formal reduction potential of the TiIII/IV couple increased as the group electronegativity of the R group of the β-diketonato ligand increased. Bulk electrolysis showed that one electron was transferred in the TiIII/IV couple and one electron in the ferrocenyl/ferrocenium redox couple in the ligand. The crystal structure for the R = OCH3 complex showed that this β-keto-ester binds through the carbonyl oxygen of the ester group and not the ether oxygen.
