Reactions of [Ti(η5-C5Me4SiMe2Cl)Cl3] with Diamines, a Suitable Approach to Prepare Mono- and Dinuclear Cyclopentadienyl-silyl-amido Titanium Complexes with Constrained and Unstrained Structures

Complex [Ti(η5-C5Me4SiMe2Cl)Cl3] (1) reacts with NH2(CH2)nNH2 (n = 3, 4), under appropriate reaction conditions, to yield the corresponding di- and mononuclear constrained-geometry cyclopentadienyl-silyl-amido complexes [Ti{η5-C5Me4SiMe2-κ-N(CH2)n/2}Cl2-]2 (n = 3, 2a; 4, 2b) and [Ti{η5-C5Me4SiMe2-κ-N(CH2)nNH2}Cl2] (n = 3, 3a; 4, 3b). Complexes 2a and 2b are obtained as pure compounds when the reaction is carried out in a 1(Ti):1.5(diamine) molar ratio, while the derivatives 3 cannot be selectively prepared. Treatment of 1 with NH2(CH2)5NH2 gives the dinuclear derivative [Ti{η5-C5Me4SiMe2-κ-N(CH2)2.5-}Cl2]2 (2c) as a single complex, regardless of the reaction stoichiometry. On monitoring these reactions by NMR spectroscopy, the formation of the transient asymmetrical dinuclear complexes [TiCl2{η5-C5Me4SiMe2-κ-N(CH2)nNH-η5-C5Me4SiMe2}TiCl3] (n = 3, 4a; 4, 4b; 5, 4c) is observed. The analogue dinuclear complex [TiCl2{η5-C5Me4SiMe2-κ-N(CH2)3NMe-η5-C5Me4SiMe2}TiCl3] (6) is synthesized, on a preparative scale, ...