Infrared predissociation spectroscopy of M+ (C6H6)(1-4)(H2O)(1-2)Ar(0-1) cluster ions, M = Li, Na

J Phys Chem A. 2011 May 5;115(17):4148-56. doi: 10.1021/jp1107526. Epub 2011 Apr 12.

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Argon / chemistry*
  • Benzene / chemistry*
  • Lithium / chemistry*
  • Quantum Theory
  • Sodium / chemistry*
  • Spectrophotometry, Infrared
  • Water / chemistry*

Substances

  • Water
  • Argon
  • Lithium
  • Sodium
  • Benzene