Effect of the intermolecular hydrogen bond conformation on the structure

A. N. OLDANI; J. C. FERRERO; G. A. PINO *

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Año: 2009 vol. 11 p. 10409 - 10416

1463-9076

The structure and reactivity of p-CrOH(NH3)2 and p-CrOH(H2O)(NH3) complexes were studied using mass resolved one colour REMPI and LIF spectroscopy together with DFT calculations. At the excitation energy of this work, the S1 state of p-CrOH(NH3)2 shows a sub-nanosecond lifetime, as determined by time resolved LIF spectra, as a consequence of an hydrogen transfer process that results in  NH4(NH3) as a reaction product. Substitution of NH3 by H2O closes the reaction channel as evidenced by the absence of ESHT reaction products, (H3O(NH3) or NH4(H2O)) and results in a dramatic effect on the S1 lifetime of the p-CrOH(H2O)(NH3) complex which rises to (12 2) ns. According to DFT calculations the most stable conformer of the p-CrOH(H2O)(NH3) complex is a cyclic structure, in which H2O acts as the H acceptor of the phenolic OH group (c-OH-H2O-NH3). However, ESHT process is energetically not allowed, upon electronic excitation.