Copolymerization of Ethylene and Vinyl Fluoride by Self-Assembled Multinuclear Palladium Catalysts

The self-assembled multinuclear Pd^II complexes {(Li-OPO^OMe2)PdMe(4-5-nonyl-pyridine)}₄Li₂Cl₂ (C, Li-OPO^OMe2 = PPh(2-SO₃Li-4,5-(OMe)₂-Ph)(2-SO₃^--4,5-(OMe)₂-Me-Ph)), {(Zn-OP-P-SO)PdMe(L)}₄ (D, L = pyridine or 4-Bu-pyridine, [OP-P-SO]^3- = P(4-^tBu-Ph)(2-PO₃^2--5-Me-Ph)(2-SO₃^--5-Me-Ph)), and {(Zn-OP-P-SO)PdMe(pyridine)}₃ (E) copolymerize ethylene and vinyl fluoride (VF) to linear copolymers. VF is incorporated at levels of 0.1-2.5 mol% primarily as in-chain -CH₂CHFCH₂- units. The molecular weight distributions of the copolymers produced by D and E are generally narrower than for catalyst C, which suggests that the Zn-phosphonate cores of D and E are more stable than the Li-sulfonate-chloride core of C under copolymerization conditions. The ethylene/VF copolymerization activities of C-E are over 100 times lower and the copolymer molecular weights (MWs) are reduced compared to the results for ethylene homopolymerization by these catalysts.