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          Institute: Fritz-Haber-Institut     Collection: Molecular Physics     Display Documents

ID: 221521.0, Fritz-Haber-Institut / Molecular Physics
Infrared Spectroscopy of Gas-Phase Cr+ Coordination Complexes: Determination of Binding Sites and Electronic States
Authors:Moore, David T.; Oomens, Jos; Eyler, John R.; Helden, Gert von; Meijer, Gerard; Dunbar, Robert C.
Date of Publication (YYYY-MM-DD):2005-04-22
Title of Journal:Journal of the American Chemical Society
Journal Abbrev.:J. Am. Chem. Soc.
Issue / Number:19
Start Page:7243
End Page:7254
Copyright:2005 American Chemical Society
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Infrared spectra were recorded for a series of gas-phase Cr+ complexes using infrared multiphoton dissociation (IRMPD) in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The functionalized aromatic ligands (acetophenone, anisole, aniline, and dimethyl aniline) offer a choice of either aromatic ring- or n-donor-base binding sites. Use of the FELIX free electron laser light source allowed convenient, rapid scanning of the chemically informative wavelength range from approximately 500 to 1800 cm-1, which in many cases characterized the preferred site of metal binding, as well as the electronic spin state of the complex. Mono-complex ions, Cr+(ligand), for anisole, aniline, and dimethyl aniline and bis-complex ions, Cr+(ligand)2, for anisole, aniline, and acetophenone were produced by ligand attachment to laser-desorbed Cr+ ions in the FT-ICR cell. The photodissociation yields plotted as a function of wavelength were interpreted as approximations to the infrared absorption spectra and were compared with computed spectra of different possible geometries and spin states. Clear-cut diagnostic features in the spectra of the acetophenone, anisole, and aniline complexes showed the sites of Cr+ attachment to be the carbonyl oxygen site for acetophenone (bis-complex) and the ring- site for anisole and aniline (both mono- and bis-complexes). The bis-complexes of aniline and anisole are low-spin (probably doublet) states, while the mono-complexes of these same ligands are high-spin (sextet) states. The dimethyl aniline complex gave a cluttered spectrum in poor agreement with calculations, which may reflect a mixture of binding-site isomers in this case.
External Publication Status:published
Document Type:Article
Communicated by:Gerard Meijer
Affiliations:Fritz-Haber-Institut/Molecular Physics
External Affiliations:FOM-Inst. for Plasma Physics "Rijnhuizen", Nieuwegein, The Netherlands; Chemistry Dept., Univ. of Florida, Gainesville, FL, USA.
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