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The effect of the concentrations of propylene oxide and the catalyst (salen)CoDNP/[PPN]Cl ((salen)CoDNP : [PPN]Cl = 1 : 1, mol/mol) on the kinetics of the copolymerization of CO 2 and propylene oxide at 0.5 MPa and 20°C has been studied. The reaction proceeds at a constant rate after an induction period, and the value of this period varies with the reagent concentrations. The steady state reaction rate increases linearly with the propylene oxide concentration in the range 5.0-14.3 mol/L. At high catalyst con centrations, such as (5.2-7.3) × 10 -3 mol/L, the reaction rate is first order in the catalyst; at concentrations below 5 × 10 -3 mol/L, the reaction rate is second order in the catalyst. Molecular mass increases in proportion to the propylene oxide conversion, that is consistent with a living polymerization process. A regioregular copolymer with 96% head to tail (HT) connectivity of propylene oxide has been obtained.

The products of the reactions of polymethylalumoxane (MAO) with triisobutylaluminum (TIBA), rac Me 2 Si(2 Me,4 PhInd) 2 ZrCl 2 (1) with MAO (1 + MAO), and (1 + MAO) + TIBA were studied by 1 H NMR at different molar ratios of the components. When the ratio Al TIBA /Al MAO is ~6, the reaction between MAO and TIBA involves the replacement of the methyl group of MAO by isobutyl groups and the formation of isobutylmethylalumoxane or mixed isobutylmethylalumoxane structures. When the TIBA content in the system increases to 30 mol.%, these structures are rearranged to form products with a low degree of association. With the equimolar ratio of the reactants, the main reaction products are tetraisobutylalumoxane and polyisobutylalumoxane. The 1 + MAO system with the molar ratio Al MAO /Zr = 50 affords a MAO bonded monomethyl monochloride derivative [L 2 ZrCl µ Me] δ+ [MAO] δ-. An in crease in this ratio to 150 produces intermediate binuclear complexes [L 2 ZrCl µ Me MeZrL 2 ] + [MAO] -and [Me 2 Al (µ Me) 2 ZrL 2 ] + [MAO] -. The addition of TIBA induces the replacement of the ZrMe groups by isobutyl groups at the first step of the interaction and formation of nonidentified reaction products at the subsequent steps.Metallocene cationic complexes of Group IVB ele ments are highly efficient catalysts for olefin homo and copolymerization. A catalyst system is formed by the reaction of a metallocene complex with an activator (cocatalyst). The concept that catalytic intermediates (precursors of the active site) are alkylmetal cationic complexes bonded to a counterion 1-4 was confirmed by numerous spectroscopic data. 5-7 Polymethylalum oxane (MAO) ( O-Al(Me) ) n (n = 4-30) contain ing a considerable amount of free or partially bound trimethylaluminum (TMA) (up to 30 mol.% with re spect to aluminum) is most frequently used as a co catalyst. 8 When activating the starting metallocene dichlo ride L 2 ZrCl 2 (L are hapto bonded cyclopentadienyl, indenyl, or fluorenyl ligands), MAO bears numerous func tions: it acts as an alkylating agent (Scheme 1, reac tion (1)), cation generating agent (reaction (2)), and, in addition, purifies the reaction medium from moisture ad mixtures. Scheme 1 L 2 ZrCl 2 + MAO L 2 ZrMeCl (1) L 2 ZrMeCl + MAO L 2 Zr + Me...ClMAO -The MAO activated catalysts are most active at low metallocene concentrations (1•10 -5 -1•10 -7 mol L -1 ) and high cocatalyst/catalyst molar ratios (1•10 3 -1•10 4 ). Disadvantages of MAO are its high cost and instability during storage. Other most popular activators are fluoaryl boranes and fluoaryl borates. 8 However, their use as acti vators is restricted, because they have no components interacting with humidity admixtures in the reaction me dium and can activate only dimethylated metallocenes. Nevertheless, there are examples for the efficient activa tion of metallocene dichlorides by a combined activator including borates and triisobutylaluminum (TIBA). 9-13 Some workers 14-16 propose an approach to metallo cene activation based on the treatment of the metallocene dichloride ...