Hydrogen bonded and nonhyphen;hydrogen bonded van der Waals clusters: Comparison between clusters of pyrazine, pyrimidine, and benzene with various solvents

摘要

Solutendash;solvent clusters of pyrazine, pyrimidine, and benzene (solutes) and CnH2n+2(n=1,2), NH3, and H2O (solvents) are studied by the techniques of supersonic molecular jet spectroscopy and twohyphen;color timehyphen;ofhyphen;flight mass spectroscopy (twohyphen;color TOFMS). Spectral shifts, van der Waals (vdW) modes, dissociation energies, and vdW modendash;solute mode vibronic couplings are characterized for most of the observed clusters. Based on these data and previous results for hydrocarbon systems, cluster geometries can be suggested. Lennardhyphen;Jones potential (6hyphen;12hyphen;1) calculations are also performed for these clusters and in all instances for which comparisons can be readily made, calculated and experimentally estimated geometries and binding energies agree completely. Clusters ofNhyphen;heterocyclic solutes and H2O are not observed experimentally. Systematics and trends among the clusters reported herein and those previously reported are discussed and analyzed.