title: Infrared predissociation spectroscopy of M+ (C6H6)(1-4)(H2O)(1-2)Ar(0-1) cluster ions, M = Li, Na.
abstract: Infrared predissociation (IRPD) spectra of Li(+)(C(6)H(6))(1-4)(H(2)O)(1-2)Ar(0-1) and Na(+)(C(6)H(6))(2-4)(H(2)O)(1-2)Ar(1) are presented along with ab initio calculations. The results indicate that the global minimum energy structure for Li(+)(C(6)H(6))(2)(H(2)O)(2) has each water forming a π-hydrogen bond with the same benzene molecule. This bonding motif is preserved in Li(+)(C(6)H(6))(3-4)(H(2)O)(2)Ar(0-1) with the additional benzene ligands binding to the available free OH groups. Argon tagging allows high-energy Li(+)(C(6)H(6))(2-4)(H(2)O)(2)Ar isomers containing water-water hydrogen bonds to be trapped and detected. The monohydrated, Li(+) containing clusters contain benzene-water interactions with varying strength as indicated by shifts in OH stretching frequencies. The IRPD spectra of M(+)(C(6)H(6))(1-4)(H(2)O)(1-2)Ar are very different for lithium-bearing versus sodium-bearing cluster ions emphasizing the important role of ion size in determining the most favorable balance of competing noncovalent interactions.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Jordan P
authors.initials: JP
authors.lastname: Beck
authors.forename: James M
authors.initials: JM
authors.lastname: Lisy
mesh_terms: D001128:Argon / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D011789:Quantum Theory; D012964:Sodium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D001128:Argon; D008094:Lithium; D012964:Sodium; D001554:Benzene