Correlation of metal spin-state in α-diimine iron catalysts with polymerization mechanism

被引：58

作者：

Allan, Laura E. N. ^{[1
]}

Shaver, Michael P. ^{[1
]}

White, Andrew J. P. ^{[1
]}

Gibson, Vernon C. ^{[1
]}

机构：

[1] Univ London Imperial Coll Sci Technol & Med, Dept Chem, London SW7 2AZ, England

来源：

INORGANIC CHEMISTRY | 2007年 / 46卷 / 21期

关键词：

D O I：

10.1021/ic701500y

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The alpha-diimine iron complexes, (R',R '')[N,N]FeCl2 ((R',R '')[N,N] = 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 paradimethylaminophenyl (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, sigma, with polymerization rate and polymer molecular weight, respectively.

引用

页码：8963 / 8970

页数：8

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