Synthesis, structure, and reactivity of rac-Me(2)Si(indenyl)(2)Zr(NMe(2))(2)

The amine elimination reaction of (SBI)H-2 (3, Me(2)Si(1-indenyl)(2)) and Zr(NMe(2))(4) (2) affords rac-(SBI)Zr(NMe(2))(2) (4) in 65% isolated yield, This reaction proceeds via initial formation of a mono(indenyl) intermediate, (eta(5)-C(9)H(6)SiMe(2)C(9)H(7))Zr(NMe(2))(3) (6). Intermediate 6 reacts reversibly with a second equivalent of 2 to form a binuclear complex, {mu-eta(5):eta(5)-Me(2)Si(1-indenyl)(2)}{Zr(NMe(2))(3)}(2) (6), which was prepared independently by the reaction of 3 and 2 equiv of 2. Complex 6 also undergoes reversible intramolecular amine elimination to form rac-4 and meso-4. The equilibrium between 6 and 4 + NMe(2)H strongly favors 6. rac-4 is the kinetic product of the intramolecular amine elimination of 6, the thermodynamic rac-4/meso-4 ratio is 4/1, and the rac-4/meso-4 isomerization is catalyzed by NMe(2)H. Therefore, the removal of NMe(2)H from the reaction mixture is the most important factor in controlling the yield of 4 and the rac-4/meso-4 ratio. The molecular structures of rac-4 and meso-5 have been determined by X-ray crystallography. rac-4 is cleanly converted to rac-(SBI)ZrCl2 (rac-1, 100% NMR) by reaction with Me(3)SiCl and to rac-(SBI)ZrMe(2) (rac-7, 92% isolated) by reaction with AlMe(3).