摘要:
Complex [Ti(eta(5)-C5Me4SiMe2Cl)Cl-3] (1) reacts with NH2(CH2)(n)NH2 (n = 3, 4), under appropriate reaction conditions, to yield the corresponding di- and mononuclear constrained-geometry cydopentadienyl-silyl-amido complexes [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)(n/2)}Cl2-](2) (n = 3, 2a; 4, 2b) and [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)(n)NH2}Cl-2] (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)(5)NH2 gives the dinuclear derivative [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)(2.5)-}Cl-2](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{eta(5)-C5Me4SiMe2-kappa-N(CH2)(n)NH-eta(5)-C5Me4SiMe2}TiCl3] (n = 3, 4a; 4, 4b; 5, 4c) is observed. The analogue dinuclear complex [TiCl2{eta(5)-C5Me4SiMe2-kappa-N(CH2)(3)NMe-eta(5)-C5Me4SiMe2}TiCl3] (6) is synthesized, on a preparative scale, by treatment of 1 with an equimolar amount of N-methylpropylenediamine, which is transformed into the mononuclear derivative [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)(3)NHMe}Cl-2] (7) upon addition of a further equivalent of the diamine. However, treatment of 1 with 1 equiv of N-methylpropylenediamine proceeds with the formation of the mononuclear constrained-geometry compound [Ti{eta(5)-CsMe4SiMe2-kappa-N(CH2)(3)NHMe center dot HCl}Cl-2] (5). The reaction of 1 with 2 equiv of NH2(CH2)(3)NMe2 or NHMe(CH2)(3)NMe2 specifically affords, respectively, a mononuclear cyclopentadienyl-silyl-amido derivative with constrained geometry, [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)(3)NMe2}Cl-2] (8), or unconstrained geometry, [Ti{eta 5-C5Me4SiMe2NMe(CH2)(3)-kappa-NMe}Cl-2] (9). When the reaction with NHMe(CH2)(3)NHMe is monitored by NMR spectroscopy, the mononuclear intermediate [Ti{eta(5)-C5Me4SiMe2NMe(CH2)(3)NHMe}Cl-3] (11) and the dinuclear complex [Ti{eta(5)-C5Me4SiMe2NMe(CH2)(1.5)-}Cl-3](2) (12) are observed. The dinuclear complex [Ti{eta(5)-C5Me4SiMe2NMe(CH2)(3)-} Cl-3](2) (13) is synthesized by treatment of 1 with 1 equiv of NHMe(CH2)(6)NHMe. All the reported compounds were characterized