Reaction of vinyl chloride with transition metal complexes

Insertion polymerization of polar monomers such as vinyl chloride (VC) may offer better control of molecular weight, molecular weight distribution, tacticity, microstructure and other properties of the product. However, it has never been evidentially achieved. This dissertation describes studies of the reaction of VC with transition metal catalysts, which are directed to the long-term objective of developing metal catalysts for the insertion polymerization/copolymerization of VC.; When no free radicals are generated, VC reacts with both early and late metal alkyl complexes L_nMR(+) by a net 1,2 insertion to yield L_nMCH₂CHClR(+) species which undergo β-Cl elimination to yield L_nMCl(+) species and the corresponding olefin. β-Cl elimination is the major obstacle to insertion polymerization of VC.; In an effort to circumvent β-Cl elimination, reactions of VC with L₂Pd{lcub}C(=O)Me{rcub}+ complexes were investigated. VC reacts with L₂Pd{lcub}C(=O)Me{rcub}+ species by 2,1 insertion to yield O-chelated L₂Pd{lcub}CHClCH₂C(=O)Me{rcub}+ products. The VC 2,1 insertion regiochemistry is favored because the alternative 1,2 insertion products, L₂Pd{lcub}CH₂CHClC(=O)Me{rcub} +, would be destabilized by placement of the electron-withdrawing Cl and acyl substituents on the same carbon atom. However, L₂Pd{lcub}CHClCH ₂C(=O)Me)+ species do not react further with VC, CO or ethylene due to the stability of the chelate ring and low migratory aptitude of the -CHClCH₂C(=O)Me group.; In contrast, VC reacts with Cp₂Zr{lcub}η2-C(=O)Me{rcub}(CO) + by 1,2-insertion and subsequent β-Cl elimination to yield methyl vinyl ketone (MVK). MVK reacts with 2 equiv of Cp₂Zr{lcub}η 2-C(=O)Me{rcub}(CO)+ to yield a dinuclear dication, which is formulated as a 1:1 adduct of Cp₂Zr{lcub}κ2-OC(Me)(CH=CH ₂)C(=O)Me{rcub} and Cp₂Zr{lcub}η2-C(=O)Me{rcub}(CO) +.; In an effort to develop catalysts for electron-withdrawing-group-directed 2,1 VC insertion polymerization, L_nPd(CHCl₂)X, L _nPd(n-C₃F₇)X and L_nPd(CH ₂Cl)X (X = Cl or alkyl) complexes were synthesized. Cationic L _nPd(CHCl₂)(L′)+ and L _nPd(n-C₃F₇)(L′) + (L′ = L_nPd(CHCl₂)Cl, NMePh₂) species do not react with VC due to the weak coordination capability of VC. Nevertheless, these species do react with ethylene and CO to form the corresponding adducts, which, however, do not insert due to the poor migratory aptitude of alkyls.