Basis set effects on the stability of the Cl2O3 isomers using B3P86 and B3LYP methods of density functional theory

Four Cl2O3 isomers have been calculated using density functional theory wit h B3P86 and B3LYP functionals and various basis sets. The energy hypersurfa ces of Cl2O3 are very flat and the relative energies of the isomers which h ave hypervalent characters such as ClOCl(O)O and ClClO3 are strongly depend ent on the basis sets. The stability for Cl2O3 isomers are in the order of (1)ClOOOCl(C-s), (2)ClOOOCl(C-2), (3)ClClO3 and (4)ClOCl(O)O with ClOCl(O)O being most stable. We suggest that at least the cc-pV6Z(-ghi) basis set fo r Cl and the cc-pVTZ basis set for O are required to obtain reliable relati ve stabilities of Cl2O3 isomers with hypervalent characters. (C) 1999 Elsev ier Science B.V. All rights reserved.