Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance work on Wednesday 27th March 2019 from 11:00 AM to 1:00 PM (GMT).

During this time our website performance may be temporarily affected. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 17, 2014
Previous Article Next Article

Microsolvation of the acetanilide cation (AA+) in a nonpolar solvent: IR spectra of AA+–Ln clusters (L = He, Ar, N2; n ≤ 10)

Author affiliations

Abstract

Infrared photodissociation (IRPD) spectra of mass-selected cluster ions of acetanilide (N-phenylacetamide), AA+–Ln, with the ligands L = He (n = 1–2), Ar (n = 1–7), and N2 (n = 1–10) are recorded in the hydride stretch (amide A, νNH, νCH) and fingerprint (amide I–III) ranges of AA+ in its 2A′′ ground electronic state. Cold AA+–Ln clusters are generated in an electron impact ion source, which predominantly produces the most stable isomer of a given cluster ion. Systematic vibrational frequency shifts of the N–H stretch fundamentals (νNH) provide detailed information about the sequential microsolvation process of AA+ in a nonpolar (L = He and Ar) and quadrupolar (L = N2) solvent. In the most stable AA+–Ln clusters, the first ligand forms a hydrogen bond (H-bond) with the N–H proton of trans-AA+ (t-AA+), whereas further ligands bind weakly to the aromatic ring (π-stacking). There is no experimental evidence for complexes with the less stable cis-AA+ isomer. Quantum chemical calculations at the M06-2X/aug-cc-pVTZ level confirm the cluster growth sequence derived from the IR spectra. The calculated binding energies of De(H) = 720 and 1227 cm−1 for H-bonded and De(π) = 585 and 715 cm−1 for π-bonded Ar and N2 ligands in t-AA+–L are consistent with the observed photofragmentation branching ratios of AA+–Ln. Comparison between charged and neutral AA(+)–L dimers indicates that ionization switches the preferred ion–ligand binding motif from π-stacking to H-bonding. Electron removal from the HOMO of AA+ delocalized over both the aromatic ring and the amide group significantly strengthens the C[double bond, length as m-dash]O bond and weakens the N–H bond of the amide group.

Graphical abstract: Microsolvation of the acetanilide cation (AA+) in a nonpolar solvent: IR spectra of AA+–Ln clusters (L = He, Ar, N2; n ≤ 10)

Back to tab navigation

Supplementary files

Publication details

The article was received on 27 Jan 2014, accepted on 24 Feb 2014 and first published on 20 Mar 2014


Article type: Paper
DOI: 10.1039/C4CP00401A
Citation: Phys. Chem. Chem. Phys., 2014,16, 7980-7995

  •   Request permissions

    Microsolvation of the acetanilide cation (AA+) in a nonpolar solvent: IR spectra of AA+–Ln clusters (L = He, Ar, N2; n ≤ 10)

    M. Schmies, A. Patzer, M. Schütz, M. Miyazaki, M. Fujii and O. Dopfer, Phys. Chem. Chem. Phys., 2014, 16, 7980
    DOI: 10.1039/C4CP00401A

Search articles by author

Spotlight

Advertisements