Ab initio calculations of the polymerization pathways of isocyanic acid HNCO

The structures, energies, vibrational frequencies and the polymerization pa thways of isocyanic acid, HNCO, into various chain polymers consisting of u p to 15 HNCO molecules have been investigated by the semi-empirical PM3/VST O-3G(d) method and by ab initio HF and MP2 calculations employing the 6-31G (d,p) basis set. In accord with earlier literature studies, it was found th at the most stable structure of isocyanic acid is not linear and the polyme rization of HNCO to oxo (keto) cyanuric acid is thermodynamically the most favorable. (C) 2001 Elsevier Science B.V. All rights reserved.