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 Cp 2 Ti(CH 3 ) 2 in dichloromethane with 1 M equivalent of [η 5 -(C 5 H 4 COOH)]Cr(CO) 2 NO ( 5 ), [η 5 -(C 5 H 4 COOH)]Cr(NO) 2 X] (X = Cl 6 , X = I 7 ) and [η 5 -(C 5 H 4 COOH)]W(CO) 3 CH 3 ( 8 ) gives Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]Cr(CO) 2 NO} ( 9 ), Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]Cr(NO) 2 Cl} ( 10 ), Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]Cr(NO) 2 I} ( 11 ) and Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]W(CO) 3 CH 3 } ( 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 Cp 2 Ti(CH 3 )– 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 13 C NMR data and those of 10 are compared with the calculations via density functional B3LYP correlation- exchange method.