Syntheses and spectra of chromium-titanium complexes bridged by carboxylate substituted cyclopentadienyl group: The structure of Cp2Ti(CH3){[OC(O)C5H4]Cr(NO)2Cl}

Mono-demethylation of Cp₂Ti(CH₃)₂ in dichloromethane with 1 M equivalent of [η⁵-(C₅H₄COOH)]Cr(CO)₂NO (5), [η⁵-(C₅H₄COOH)]Cr(NO)₂X] (X = Cl 6, X = I 7) and [η⁵-(C₅H₄COOH)]W(CO)₃CH₃ (8) gives Cp₂Ti(CH₃){[OC(O)C₅H₄]Cr(CO)₂NO} (9), Cp₂Ti(CH₃){[OC(O)C₅H₄]Cr(NO)₂Cl} (10), Cp₂Ti(CH₃){[OC(O)C₅H₄]Cr(NO)₂I} (11) and Cp₂Ti(CH₃){[OC(O)C₅H₄]W(CO)₃CH₃} (12), respectively. The structure of 10 has been solved by X-ray diffraction studies. One of the nitrosyl groups is located at the site away from the exocyclic carbonyl carbon of the Cp(Cr) ring with twist angle of 178.1°. All the data reveals that Cp₂Ti(CH₃)- is a strong electron-donating group. The opposite correlation was observed on the chemical shift assignments of C(2)-C(5) in compounds 5-12, using HetCOR NMR spectroscopy, as compared with the NMR data of their ferrocene analogues. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of ¹³C NMR data and those of 10 are compared with the calculations via density functional B3LYP correlation- exchange method.