Syntheses, crystal structure and theoretical modelling of tetrahedral mono-β-diketonato titanocenyl complexes

A comparative investigation on three novel bis(cyclopentadienyl) mono(β-diketonato) titanium(IV) complexes, [Cp2TiIV(R1COCHCOR2)]+ClO4− (Cp = η5-C5H5), i.e. [Cp2Ti(tfba)]+, [Cp2Ti(tfth)]+ and [Cp2Ti(tfba)]+ where tfba = CF3COCHCOC6H5−, tfth = CF3COCHCOC4H3S− and tffu = CF3COCHCOC4H3O−, has been performed based on structural data and DFT calculations. The preparation of [Cp2TiIV(β-diketonato)]+ClO4− involves the reaction of Cp2TiCl2 with AgClO4 and the respective β-diketones. The crystal structures show that the structures are isomorphous. All the complexes exhibit π-stacking between one Cp ring and the aromatic R-group ring, i.e. the C6H5, C4H3S and C4H3O fragments, respectively. The DFT calculations show that the formal 16-electron count of these d0 titanium(IV) complexes is increased via Ti ← O π bonding. The bonding mode in the [Cp2Ti(β-diketonato)]+ complexes is different from that in Cp2Ti(OR)2 and Cp2Ti(dioxolene) complexes.

Graphical abstractCrystallographic and computational study of new titanocenyl complexes of the type [Cp2Ti(CF3COCHCOR)]+ClO4−, where R = C6H5, C4H3S and C4H3O.Figure optionsDownload full-size imageDownload as PowerPoint slide