# title
Perfectly Alternating and Regioselective Copolymerization of Carbonyl Sulfide and Epoxides by Metal-Free Lewis Pairs.

# abstract
The preparation of perfectly alternating and regioslective copolymers derived from the copolymerization of carbonyl sulfide (COS) and epoxides by metal-free Lewis pair catalysts composed of a Lewis base (amidine, guanidine, or quaternary onium salts) and a Lewis acid (triethyl borane) is described. Colorless and highly transparent copolymers of poly(monothiocarbonate) were successfully obtained with over 99% tail-to-head content and high molecular weight (up to 92.5kgmol-1 ). In most instances, oxygen-sulfur exchange reactions (O/S ERs), which would generate random thiocarbonate and carbonate units, were effectively suppressed. The turnover frequencies (TOF) of these Lewis pair catalyzed processes were as high as 119h-1 at ambient temperature.

# authors[].organizations[].label
Texas A&M Engineering Experiment Station (TEES)

# authorList[]
Yang, J., Wu, H., Li, Y., Zhang, X., & Darensbourg, D. J.