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(eta(5)-C5Me4SiMe2Cl)Cl-3] (1) with 1 equiv of different ethylenediamines, NHR-(CH2)(2)NR'R '', regiospecifically affords cyclopentadienyl-silyl-amido derivatives with constrained geometry, [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)(2)NR'R ''}Cl-2] (R' = R '' = H, 2a; R' = H, R '' = Me, 2b; R' = R = Me, 2c) or unstrained structure, [Ti{eta(5)-C5Me4SiMe2NMe(CH)(2)-kappa-NMe)Cl-2] (3). Treatment of 1 with 1.5 equiv of ethylenediamine gives a mixture of 2a and the transient complex [Ti{eta(5)-C5Me4SiMe2NH(CH2)(2)NH2}Cl-3] (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{eta(5)-C5Me4SiMe2NMe(CH2)(2)NMe2]Cl-3](5). Compound 1 reacts with 0.5 equiv of NH2(CH2)(2)NH2 to yield a mixture of 2a along with the tethered dinuclear cyclopentadienyl-silyl-amido compound [Ti{eta(5)-C5Me4SiMe2-kappa-N(CH2)-} Cl-2](2) (6).