Structure and binding energies of halogenated hydroxymethoxy radical-water hydrogen-bonded complexes: HO-C(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, HO-C(X)(Y)-O center dot nH(2)O (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 HO-C(X)(Y)-O center dot nH(2)O complexes (n = 0,1) have also been calculated by CCSD/aug-cc-pVDZ and CCSD/aug-cc-pVTZ methods. The HO-C(X)(Y)-O center dot nH(2)O 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 HO-C(X)(Y)-O center dot 2H(2)O complexes. The effect of type and number of halogen atoms bonded to the central carbon atom of HO-C(X)(Y)-O radical on structure, hydrogen bonding, Mulliken spin, Mulliken charge and vibrational frequency is discussed. (C) 2012 Elsevier B.V. All rights reserved.