Replacement in Transition Metal Alkyl Compounds and Polymerization Activity

Ligand Replacement in Transition Metal Alkyl Compounds and Polymerization Activity 

Zr(allyl)4 + C3H3Br Zr(allyl)3Br + C3H3C3H6 Zr(allyl)3Br + C3H3Br — Zr(allyl)2Br2 + C3H3C3H5 (9) 

Similar reactions occur with all aliphatic halides and the rates of substitution are related to the degree of ionic character of the carbon-halogen bond. For preparation purposes, trityl bromide or propargyl bromide are more convenient than allyl bromide. The compounds obtained are listed in Table XI. They were obtained pure and characterized fully. Zr (allyl) 3Br and Zr(allyl)2Br2 are sufficiently soluble in toluene for polymerizations to be initially homogeneous. Their relative reactivities are listed in Table XI. In all cases hydrogen was used to reduce the molecular weight of the polymer formed. In this respect the polymer derived from Zr (allyl )3Br was more readily modified than that from Zr (allyl) 4, but in order to avoid 

Polymerization of Ethylene by Zirconium Alkyl Halides in Toluene at 80°C. Concentration 3.00 X 10 3 mole liter-1 Ethylene Partial Pressure 10 atm.Hydrogen Partial Pressure 10 atm (9, 16) 

Compound (C2H6)20 (mole liter-1) X 10 Relative reactivities 

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