DFT study on the mechanism of trimolecular radical reactions: isomerisation in small clusters

ABSTRACT

Structural and thermodynamic properties of 48 trimolecular clusters containing one radicl and two protic molecules (H₂O, NH₃, H₂O₂, CH₃OH, HOCl) were studied at B3LYP/6-311++G(3df,3pd) level of theory. These radical-clusters have non-cyclic structures and are stabilised via two inter-molecular hydrogen bonding interactions. The calculated enthalpies of formation of the radical-clusters were generally in the range of ?30 to ?50 kJ/mol. The calculated activation energies (E_a) of the intra-cluster hydrogen transfers were smaller than 70 kJ/mol. Also, structures and thermodynamics of 15 cyclic molecular clusters as well as multi-hydrogen transfers in them were investigated. The results showed that the stability of the cyclic clusters and activation energies of the multi-hydrogen transfers depend on the cluster size.