Structure and binding energies of halogenated hydroxymethoxy radical–water hydrogen-bonded complexes: HOC(X)(Y)O·nH2O (n = 0, 1, 2 and X, Y = H/F/Cl)

The structure, hydrogen bonding and binding energy of hydroxymethoxy radical–water complexes, HOC(X)(Y)O·nH2O (n = 0, 1, 2 and X, Y = H/F/Cl), have been investigated using MP2 method with the 6-311++G(d, p) basis set. Hessian calculations have been done to check the nature of the equilibrium geometry. The energy values of selective HOC(X)(Y)O·nH2O complexes (n = 0,1) have also been calculated by CCSD/aug-cc-pVDZ and CCSD/aug-cc-pVTZ methods. The HOC(X)(Y)O·nH2O complexes (n = 1, 2 and X, Y = H/F/Cl) have been found to possess cyclic structures with binding energies between 8.0 and 22.2 kcal/mol. Cooperative effect on the hydrogen bond energy is found to be quite significant for the HOC(X)(Y)O·2H2O complexes. The effect of type and number of halogen atoms bonded to the central carbon atom of HOC(X)(Y)O radical on structure, hydrogen bonding, Mulliken spin, Mulliken charge and vibrational frequency is discussed.