M−Cl/Si−Cl Preferential Reactivity in Chlorosilyl-Substituted Cyclopentadienyl Early Transition Metal Complexes in Reactions with Amines: Key to Understanding the Nature of the Final Product

The reaction of [Ti(η5-C5Me4SiMe2Cl)Cl3] (1) with 1 equiv of different ethylenediamines, NHR(CH2)2NR′R′′, regiospecifically affords cyclopentadienyl-silyl-amido derivatives with constrained-geometry, [Ti{η5-C5Me4SiMe2-κ-N(CH2)2NR′R′′}Cl2] (R′ = R′′ = H, 2a; R′ = H, R′′ = Me, 2b; R′ = R′′ = Me, 2c) or unstrained structure, [Ti{η5-C5Me4SiMe2NMe(CH2)2-κ-NMe}Cl2] (3). Treatment of 1 with 1.5 equiv of ethylenediamine gives a mixture of 2a and the transient complex [Ti{η5-C5Me4SiMe2NH(CH2)2NH2}Cl3] (4), which is transformed into 2a upon addition of a base. The reaction of 1 with N,N,N′-trimethylethylenediamine permits the synthesis and isolation of the complex [Ti{η5-C5Me4SiMe2NMe(CH2)2NMe2}Cl3] (5). Compound 1 reacts with 0.5 equiv of NH2(CH2)2NH2 to yield a mixture of 2a along with the tethered dinuclear cyclopentadienyl-silyl-amido compound [Ti{η5-C5Me4SiMe2-κ-N(CH2)-}Cl2]2 (6).