Structures of catechol(H2O)1,3 clusters in the S0 and D0 states

The structures of neutral catechol, catechol(H2O)(1), and catechol(H2O)(3) are investigated by IR/R2PI spectroscopy and ab initio calculations at the HF and MP2 level of theory. Furthermore, the structure of the ionic catechol(H2O)(1)(+) cluster is derived from resonant IR-photodissociation spectroscopy as well as ab initio calculations. Trans-linear arrangements are obtained for the neutral (S-0) and ionic (D-0) ground state of the catechol(H2O)(1) cluster. In the case of the neutral catechol(H2O)(3) cluster (S-0 state) a cyclic and a pi -bonded structure are discussed which are of similar stability. From the IR spectrum of catechol(H2O)(3) it can be derived that the cyclic structure is the most probable arrangement. The calculated OH stretching frequencies of this structure are in good agreement with the experimentally observed values.