Method of obtaining a catalyst

A catalyst is prepared by combining a bis(cyclopentadienyl)zirconium compound which may be represented by one of the following general formulae: (A-Cp)MX1X2 (A-Cp)MX'1X'2 (A-Cp)ML; and (Cp*)(CpR)MX1 wherein: M is a metal selected from the Group consisting of titanium (Ti), zirconium (Zr) and hafnium (Hf); (A-Cp) is either (Cp)(Cp*) or Cp-A'-Cp* and Cp and Cp* are the same or different substituted or unsubstituted cyclopentadienyl radicals; A' is a covalent bridging group containing a Group IV-A element; L is an olefin, diolefin or aryne ligand; X1 and X2 are, independently, selected from the Group consisting of hydride radicals, hydrocarbyl radicals, substituted-hydrocarbyl radicals, organo-metalloid radicals and the like; X'1 and X'2 are joined and bound to the metal atom to form a metallacycle, in which the metal, X'1 and X'2 form a hydrocarbocyclic ring having from about 3 to about 20 carbon atoms; and R is a substituent on one of the cyclopentadienyl radicals which is also bound to the metal atom. with a second compound comprising a cation capable of donating a proton and a bulky, labile anion comprising a plurality of boron atoms capable of stabilizing the zirconium cation formally having a coordination number of 3 and a valence of +4 which is formed as a result of the combination, said second compound having one of the following general formulae: [L'-H][(CX)a(BX')mX''b]<c-> Wherein: L'-H is either H<+>, ammonium or a substituted-ammonium radical having up to 3 hydrogen atoms replaced with a hydrocarbyl or substituted-hydrocarbyl radical, a phosphonium or substituted-phosphonium radical having up to 3 hydrogen atoms replaced with a hydrocarbyl or substituted-hydrocarbyl radical and the like; B and C are, respectively, boron and carbon; X, X' and X'' are radicals selected, independently, from the Group consisting of hydride radicals, halide radicals, hydrocarbyl or substituted-hydrocarbyl radicals, organo-metalloid radicals and the like; a and b are integers >/= 0; c is an integer >/= 1; a + B + c = an even-numbered integer from 2 to about 8, and m is an integer ranging from 5 to about 22. [L'-H][[[(CX3)a'(BX4)m'(X5)b']<c'->]2M<n+>] <d-> Wherein: L'-H is either H<+>, ammonium or a substituted-ammonium radical having up to 3 hydrogen atoms replaced with a hydrocarbyl or substituted-hydrocarbyl radical, a phosphonium or substituted-phosphonium radical having up to 3 hydrogen atoms replaced with a hydrocarbyl or substituted-hydrocarbyl radical and the like; B, C, M and H are, respectively, boron, carbon, a transition metal and hydrogen; X3, X4 and X5 are radicals selected, independently, from the Group consisting of hydride radicals, halide radicals, hydrocarbyl or substituted-hydrocarbyl radicals, organo-metalloid radicals and the like; a' and b' are the same or a different integer >/= 0; c' is an integer >/= 2; a' + b' + c' = an even-numbered integer from 4 to about 8; m' is an integer from 6 to about 12; n is an integer such that 2c'- n = d' and d is an integer >/= 1. Many of the catalysts thus formed are stable and isolable and may be recovered and stored. The catalysts may be preformed and then used to polymerize olefins or the catalysts may be formed in situ during polymerization by adding the separate components to the polymerization reaction. The catalysts will be formed when the two components are combined at a temperature within the range from about -100 DEG C to about 300 DEG C. The catalysts thus prepared afford better control of polymer molecular weight and are not subject to equilibrium reversal. The catalysts thus produced are also less pyrophoric than the more conventional Ziegler-Natta olefin polymerization catalysts.