title: (Tetramethyltetraazaannulene)chromium chloride: a highly active catalyst for the alternating copolymerization of epoxides and carbon dioxide.
abstract: A tetramethyltetraazaannulene complex incorporating a chromium(III) metal center has been shown to be highly active toward the copolymerization of cyclohexene oxide and carbon dioxide to afford poly(cyclohexene carbonate) in the presence of [PPN]N3 [PPN+=bis(triphenylphosphoranylidene)ammonium] as a cocatalyst. An asymptotical rate increase was observed, leveling at 2 equiv of cocatalyst with a maximum turnover frequency of 1300 h(-1) at 80 degrees C. A benefit of this new catalyst system over that of the previously studied less-active (salen)CrX system is that the (tmtaa)CrCl catalyst has a much lower propensity toward the formation of a cyclic carbonate byproduct throughout the copolymerization reaction.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA. djdarens@mail.chem.tamu.edu
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Darensbourg
authors.forename: Shawn B
authors.initials: SB
authors.lastname: Fitch