Fluctuating Behavior and Ligand-Dependent Reactivity of Isocyanates with Bis(pentafulvene)titanium Complexes.

Reactions of bis(π-η5:σ-η1-pentafulvene)titanium complexes with isocyanates result in selective insertions of either one or two equivalents of RN═C═O into the two frustrated Ti-Cexo bonds under mild conditions. Depending on the pentafulvene ligand, K1O- and K1N-amidato titanium complexes are obtained and comprehensively characterized by single crystal X-ray diffraction and NMR and IR spectroscopy. In case of single insertion products, the reactivity of the second pentafulvene ligand is investigated with respect to E-H cleavage reactions (alcohols, amines) and insertion reactions of multiple-bond-containing substrates (ketones, nitriles). Transformations of the obtained K1N- to the respective K1O-amidato complexes are observed and investigated by DFT studies and variable temperature NMR experiments.