Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

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Cohen, C.T. et al.

Copolymerization of cyclohexene oxide and carbon dioxide using (salen)Co(III) complexes: synthesis and characterization of syndiotactic poly(cyclohexene carbonate).

Synthetic routes to a series of new (salen-1)CoX (salen-1 = N,N'-bis(salicylidene)-1,2-diaminoalkane; X = halide or carboxylate) species are described and the X-ray crystal structures of two (salen-1)CoX (salen- = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane; X = Cl, I) complexes are presented. (R,R)-(salen-)CoX (X = Cl, Br, I, OAc, pentafluorobenzoate (OBzF(5))) catalysts are active for the copolymerization of cyclohexene oxide (CHO) and CO(2), yielding syndiotactic poly(cyclohexene carbonate) (PCHC), a previously unreported PCHC microstructure. Variation of the salen ligand and reaction conditions, as well as the inclusion of [PPN]Cl ([PPN]Cl = bis(triphenylphosphine)iminium chloride) cocatalysts, has dramatic effects on the polymerization rate and the resultant PCHC tacticity. Catalysts rac-(salen-)CoX (salen- = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminopropane; X = Br, OBzF(5)) have high activities for CHO/CO(2) copolymerization, yielding syndiotactic PCHCs with up to 81% r-centered tetrads. Using Bernoullian statistical methods, PCHC tetrad and triad sequences were assigned in the (13)C NMR spectra of these polymers in the carbonyl and methylene regions, respectively.[1]

References

Copolymerization of cyclohexene oxide and carbon dioxide using (salen)Co(III) complexes: synthesis and characterization of syndiotactic poly(cyclohexene carbonate). Cohen, C.T., Thomas, C.M., Peretti, K.L., Lobkovsky, E.B., Coates, G.W. Dalton transactions (Cambridge, England : 2003) (2006) [Pubmed]

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