Fe acac 3

Iron(iii) acetylacetonate (Fe(acac)₃) and diethyl phosphite (DEP) were purchased from J&K (Beijing, China) and diluted to 0.06 mol L⁻¹ solution in toluene. Al(ⁱBu)₃ (1.0 mol L⁻¹ in toluene) was a commercial product of Akzo Nobel and used as received. 1,3-Butadiene was supplied by Jinzhou Petrochemical Corporation in China and purified by passing through four columns packed with activated molecular sieves (4 Å) and KOH prior to use. Toluene and THF were refluxed over sodium/diphenylketyl under nitrogen and then distilled before use. All other commercial chemicals were used as received.
¹H NMR spectra were recorded on a Varian Unity-400 MHz spectrometer at 125 °C in C₆D₄Cl₂. IR spectra was recorded on BRUKE Vertex-70 FIR spectrophotometer. The molecular weights and molecular weight distributions of the polymers were estimated by gel permeation chromatography (GPC) on a PL-GPC 220 high-temperature chromatograph at 150 °C. 1,2,4-Trichlorobenzene containing 0.05% (w/v) BHT was used as eluent at a flow rate of 1.0 mL min⁻¹ and the values of M_n and M_w/M_n were calculated by using polystyrene calibration. The melting points were estimated on a Q100 DSC (TA Instruments) under nitrogen atmosphere. The samples were heated and cooled down at a rate of 10 °C min⁻¹.