title: Geometry and spectral properties of the protonated homodimer of pyridine in the liquid and solid states. A combined NMR, X-ray diffraction and inelastic neutron scattering study.
abstract: The structure and spectral signatures of the protonated homodimer of pyridine in its complex with a poorly coordinating anion have been studied in solution in CDF(3)/CDClF(2) down to 120 K and in a single crystal. In both phases, the hydrogen bond is asymmetric. In the solution, the proton is involved in a fast reversible transfer that determines the multiplicity of NMR signals and the sign of the primary H/D isotope effect of --0.95 ppm. The proton resonates at 21.73 ppm that is above any value reported in the past and is indicative of a very short hydrogen bond. By combining X-ray diffraction analysis with model computations, the position of the proton in the crystal has been defined as d(N-H) = 1.123 Å and d(H···N) = 1.532 Å. The same distances have been estimated using a (15)N NMR correlation. The frequency of the protonic out-of-plane bending mode is 822 cm(-1) in agreement with Novak's correlation.
authors.affiliation: Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kong
authors.forename: A O
authors.initials: AO
authors.lastname: Borissova
authors.forename: S B
authors.initials: SB
authors.lastname: Lesnichin
authors.forename: M
authors.initials: M
authors.lastname: Hartl
authors.forename: L L
authors.initials: LL
authors.lastname: Daemen
authors.forename: J
authors.initials: J
authors.lastname: Eckert
authors.forename: M Yu
authors.initials: MY
authors.lastname: Antipin
authors.forename: I G
authors.initials: IG
authors.lastname: Shenderovich
mesh_terms: D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D033363:Neutron Diffraction; D011522:Protons; D011725:Pyridines / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D011522:Protons; D011725:Pyridines; C023666:pyridine