956376-05-9Relevant academic research and scientific papers
Correlation of metal spin-state in α-diimine iron catalysts with polymerization mechanism
Allan, Laura E. N.,Shaver, Michael P.,White, Andrew J. P.,Gibson, Vernon C.
, p. 8963 - 8970 (2008/10/09)
The α-diimine iron complexes, R′,R″[N,M]FeCl2 (R′R″[N,M] = R′-N=CR″-CR″=N-R′, where R′ = tert-butyl (tBu), cyclohexyl (Cy) and R′ = phenyl (Ph), para-fluorophenyl (F-Ph), para-bromophenyl (Br-Ph), para-methylphenyl (Me-Ph), or para-methoxyphenyl (MeO-Ph)), are found to polymerize styrene through a catalytic chain transfer (CCT) mechanism. Magnetic moment measurements indicate that Fe(III) complexes containing these ligands possess intermediate (S = 3/2) spin-state iron centers. In contrast, Fe(III) complexes bearing proton (R″ = H) and para-dimethylaminophenyl (R″ = NMe2-Ph) substituents are high-spin and are efficient atom transfer radical polymerization (ATRP) catalysts. Hammett plots show a linear correlation of the substituent constant, σ, with polymerization rate and polymer molecular weight, respectively.
