Ethylene-4-methyl-1-pentene copolymers of complex chain architecture using α-diimine Ni(ii) catalysts: synthesis, 13C NMR assignment and understanding the chain-walking mechanismElectronic supplementary information (ESI) available: 1H, 1H-1H TOCSY, and 1H-1H COSY experiments of run 6 in Table 1. A Tg plot for runs 1-6. Ethyl, propyl, and butyl branch distribution. See DOI: 10.1039/c3py01508d

Ethylene (E) and 4-methyl-1-pentene (4M1P) are copolymerized using an α-diimine Ni( ii ) catalyst with MAO (methylaluminoxane) or Et 2 AlCl (diethylaluminium chloride) as the cocatalyst. A series of copolymers with a 4M1P comonomer content ranging from 0.94 to 36.73 mol% are obtained. A detailed 13 C NMR assignment is presented and this thorough analysis has opened up the first full description of this interesting family of copolymers. Manifold branched copolymers are obtained with no noticeable differences in the branching distribution by using MAO or Et 2 AlCl. The resonance assignments are correlated with the chain-walking mechanism: branching analysis shows that the total amount of 2,1 insertion of the comonomer, followed by backward migration of the nickel active species along the polymer chain, is higher than that of 1,2 inserted 4M1P. E/4M1P copolymers were synthesized with an α-diimine Ni( ii ) catalyst with MAO or Et 2 AlCl as the cocatalyst affording a branching structure.