Patent ID: 8629292

Claim:
A method of making a stereo-enriched ansa-metallocene compound having formula (I): E(CpR A n ) 2 M(NR 2 ) m (I), the method comprising: reacting a compound having formula (II): E(CpR A n ) 2 M A 2 (II) with an unchelated amine compound having formula (III): M(NR 2 ) m X p L q (III); wherein: M is Ti, Zr, Hf, Cr, Sc, Y, La, or a lanthanide; Cp is a cyclopentadienyl, indenyl, or fluorenyl group; E is a substituted or unsubstituted bridging chain of 3 to 8 carbon atoms or 2 to 8 silicon, germanium, or tin atoms, wherein any substituents on atoms of the bridging chain independently are H or a hydrocarbyl group having up to 18 carbon atoms; each R independently is H, a hydrocarbyl, hydrocarbylsilyl, hydrocarbylamino, Or hydrocarbyloxide group having up to 18 carbon atoms, or each NR 2 group is a heterocyclic group having up to 18 carbon atoms; each R A independently is H or a hydrocarbyl, hydrocarbylsilyl, hydrocarbylamino, or hydrocarbyloxide group having up to 18 carbon atoms; m is 2, p is 2, and q is 0, 1, or 2 when M is Ti, Zr, or Hf; m is 1, p is 2, and q is 0, 1, 2, or 3 when M is Cr, Sc, Y, La, or a lanthanide; n is 0, 1, 2, 3, or 4 when Cp is an indenyl group; n is 1, 2, 3, or 4 when Cp is a cyclopentadienyl or a fluorenyl group; each M A independently is Li, Na, K, SiR B 3 , AlR B 2 , SnR B 3 , ½ Mg, ½ Zn, MgX, or ZnX, wherein R B is an alkyl group having up to 18 carbon atoms; each X independently is triflate, a halide, or a sulfonate; and each L independently is a neutral Lewis base donor ligand.