LAUSR

The reactions of the monopentafulvene complexes Ti1a and Ti1b with the general formula [Cp*Ti(Cl)(π-η5:σ-η1-C5H4═CR2)] (R = p-tolyl (Ti1a); CR2 = adamantylidene (Ti1b)) with the bidentate P,O-ligand precursor L1, featuring a diphenylphosphine and a hydroxyl functional group, are reported, yielding the corresponding complexes Ti2a and Ti2b in good yields as the result of deprotonation. A chloride/methyl exchange reaction and subsequent reaction with B(C6F5)3 was envisaged to yield the corresponding cationic complexes. Instead, the methylation reactions of Ti2a and Ti2b with methyllithium or methylmagnesium bromide selectively yielded the doubly methylated titanium complexes Ti3a and Ti3b with abstraction of LiCl and the lithium salt of the bidentate P,O-ligand. To avoid this reaction, the P,O-ligand precursor L2 was prepared, featuring a carbonyl group instead of the hydroxyl functional group. This change in the general reaction sequence allowed the preparation of a new family of cationic titanium complexe...