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.