Reactions of Secondary Allylamines with Bis(η5:η1‑pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

The N–H and C–H bond activation reactions at ambient conditions of seven different secondary allyl amines (Aa–g) with bis­(η5:η1-pentafulvene)titanium complexes (1) have been investigated. Bis­(η5:η1-adamantylidenepentafulvene)­titanium (1a) reacts with N-allylaniline (Aa), N-allylbenzylamine (Ac), N-allyl-tert-butylamine (Ad), N-allylcyclohexylamine (Ae), and N-allyl-2-methylaniline (Af) to give the 1-azabutadiene complexes 2a,c–f with high yields. They are the first complexes of the CH2-terminated monoazadiene RNCHCHCH2. Using bis­(η5:η1-di-p-tolylpentafulvene)­titanium (1b), which exhibits a less Brønsted basic Cexo center, and Aa, the β-C–H bond activation can be slowed down so much that the agostic interaction between the titanium center and the C–H bond is detectable via NMR measurements at room temperature. In the reactions of the titanium azabutadiene complexes 2a,b and 3a with carbon monoxide a ligand exchange is observed, forming the titanocene dicarbonyls 4a,b.