tert-Butyl isocyanide reacts with the m 3 -alkylidyne complex [{TiCp*(m-O)} 3 (m 3 -CH)] (1, Cp* h 5 -C 5 Me 5 ) to give a single insertion into a m 3 -carbon ± titanium bond and the formation of the new derivative [{TiCp* (m-O)} 3 (m 3 -h 2 -HCCNtBu)] (3). Similar reactions of 2,6-Me 2 C 6 H 3 NC and 2,4,6-Me 3 C 6 H 2 NC with the complexes [{TiCp*(m-O)} 3 (m 3 -CR)] (R H (1), Me (2)) in a 1:2 molar ratio at room temperature lead to the double insertion compounds
Curiously, when the reactions with 2,6-Me 2 C 6 H 3 NC are carried out in a 1:1 molar ratio, diinsertion products 6 or 8, and unchanged m 3 -alkylidyne complex 1 or 2, respectively, are detected. From the mixture of 6 and 1 the monoinsertion product 10) is formed slowly at room temperature. However, it is necessary to heat the mixture of 8 and 2 at 130 8C for five days to observe some evolution; this finally leads to the zwitterionic compound [{TiCp*(m-O)} 3 -
Complex 1 also reacts with excess carbon monoxide at room temperature to produce only compound [{TiCp*(m-O)} 3 ] 2 (m 6 -L)] (L C 6 H 2 O 4 ) (5), in which the organic ligand L connects two Ti 3 O 3 cores. The molecular structures of complexes 9 and 11 have been determined by X-ray diffraction analyses.