N-heterocyclic carbene (NHC) adducts of iron?trihalide FeX3 (X = Cl, Br), FeX3(IDipp) (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and FeX3(HIDipp) (HIDipp = 1,3-Bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene) were prepared and investigated for catalytic activity in initiators for continuous activator regeneration atom?transfer radical polymerization (ICAR ATRP). Cyclic voltammetry (CV) showed a single reversible redox process and a redox potential (E1/2) of about -480 mV (X = Cl) and -350 mV (X = Br), which indicated that FeX3(NHC)s might be efficient catalysts for ICAR ATRP. All FeX3(NHC)s were found to be active catalysts for ICAR ATRP of methyl methacrylate?(MMA) and styrene (St). While each FeX3(NHC) showed almost the same activity, using FeBr3(NHC)s resulted in better controllability. For example, ICAR ATRP of MMA, using 50 ppm of FeCl3(HIDipp) or FeBr3(HIDipp) as a catalyst and azobis(isobutyronitrile) (AIBN) as a thermal radical initiator in 50% (v/v) anisole at 60 �C,? reached 65% conversion in 24 h and gave poly(MMA) with a molecular weight distribution (Mw/Mn) of 1.44 and 1.20 respectively. ICAR ATRP of St was also investigated. The conversion reached 44% in 48 h and the polymerization was well controlled, giving poly(St) with Mw/Mn =? 1.15, using 50 ppm of FeBr3(IDipp) and AIBN in 50% (v/v) anisole at 60 �C. The number average molecular weight (Mn) corresponded well with theoretical values, as conversion increased in polymerizations of both MMA and St. 

FeX<sub>3</sub>(NHC) catalyzed ICAR ATRP of MMA and St

248th National Meeting (2014)

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FeX3(NHC) catalyzed ICAR ATRP of MMA and St

FeX₃(NHC) catalyzed ICAR ATRP of MMA and St