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)}(4)Li(2)Cl(2) (C, Li-OPO(OMe2) = PPh(2-SO(3)Li-4,5-(OMe)(2)-Ph)(2-SO(3)(−)-4,5-(OMe)(2)-Me-Ph)), {(Zn-OP-P-SO)PdMe(L)}(4) (D, L = pyridine or 4-(t)Bu-pyridine, [OP-P-SO](3−) = P(4-(t)Bu-Ph)(2-PO(3)(2−)-5-Me-Ph)(2-SO(3)(−)-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 -CH(2)CHFCH(2)- 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.