Synthesis, characterization and functionalization of titanium κ1N amidinato complexes from carbodiimides

Abstract

A series of titanium amidinato complexes were synthesized by stoichiometric insertion reactions of carbodiimides into bis(π–η⁵:σ–η¹-pentafulvene)titanium complexes. NMR studies and single-crystal X-ray diffraction showed κ¹N coordination of the former carbodiimides to the metal center. DFT calculations were performed, confirming the clear preference for a single nitrogen atom coordinating to the metal center with a high energy transition state for the formation of a chelating heteroallyl ligand. Depending on the pentafulvene ligand, additional insertion reactions of carbodiimides into the remaining Ti–C_exo bond were observed. This allows for a stepwise insertion of the corresponding carbodiimides and offers the possibility to further functionalize the complexes. The reactivity of the remaining pentafulvene ligand is further demonstrated in reactions with H-acidic and multiple bond substrates.