| Characterizing hydrogen bonding and proton transfer in 2:1 FH:NH3 and FH:collidine complexes through one- and two-bond spin-spin coupling constants across hydrogen bonds. | |
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MedLine Citation:
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PMID: 16863125 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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Ab initio equation-of-motion coupled cluster singles and doubles calculations have been carried out on a variety of 2:1 FH:NH(3) complexes (F(b)H(b):F(a)H(a):NH(3)) to investigate the effects of structural changes on one- and two-bond spin-spin coupling constants across F(a)-H(a)-N and F(b)-H(b)-F(a) hydrogen bonds and to provide insight into experimentally measured coupling constants for 2:1 FH:collidine (2:1 FH:2,4,6-trimethylpyridine) complexes. Coupling constants have been computed for 2:1 FH:NH(3) equilibrium structures and proton-transferred perpendicular and open structures at 2:1 FH:NH(3), FH:pyridine, and FH:collidine geometries. (2h)J(Fa)(-)(N), (1)J(Fa)(-)(Ha), and (1h)J(Ha)(-)(N) exhibit expected dependencies on distances, angles, and the nature of the nitrogen base. In contrast, one- and two-bond coupling constants associated with the F(b)-H(b)-F(a) hydrogen bond, particularly (2h)J(F)()b(-)(F)()a, vary significantly depending on the F-F distance, the orientation of the hydrogen-bonded pair, and the nature of the complex (HF dimer versus the anion FHF(-)). The structure of the 2:1 FH:collidine complex proposed on the basis of experimentally measured coupling constants is supported by the computed coupling constants. This study of the structures of open proton-transferred 2:1 FH:NH(3), FH:pyridine, and FH:collidine complexes and the coupling constants computed for 2:1 FH:NH(3) complexes at these geometries provides insight into the role of the solvent in enhancing proton transfer across both N-H(a)-F(a) and F(b)-H(b)-F(a) hydrogen bonds. |
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Authors:
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Janet E Del Bene; José Elguero |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The journal of physical chemistry. A Volume: 109 ISSN: 1089-5639 ISO Abbreviation: J Phys Chem A Publication Date: 2005 Dec |
Date Detail:
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Created Date: 2006-07-25 Completed Date: 2007-06-18 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9890903 Medline TA: J Phys Chem A Country: United States |
Other Details:
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Languages: eng Pagination: 10759-69 Citation Subset: - |
Affiliation:
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Department of Chemistry, Youngstown State University, Youngstown, Ohio 44555, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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