title: Combined XRD and infrared studies of pyridinium species in (PyH)(3)[PW(12)O(40)] single crystals.
abstract: The pyridinium salts of 12-tungstophosphoric acid (PyH)(3)[PW(12)O(40)]·2CH(3)CN (1) and (PyH)(3)[PW(12)O(40)] (2) have been prepared and studied by single crystal and powder X-ray diffraction (XRD) in order to characterize the crystallographic sites occupied by the pyridinium species. The three PyH(+) species are located on two unequivalent sites. Two species are linearly H-bonded to the oxygen atoms of the Keggins unit (α species), whereas the third one (β) forms a bent H-bond. In order to determine the infrared bands characterizing each type of pyridinium species in the 1650-1300 cm(-1) range, infrared spectra have been recorded from room temperature to 100 K. They reveal that only α pyridinium species give rise to the unusual splitting of the PyH(+)ν8b and ν19b modes, whereas β pyridinium species lead to a classical pyridinium spectrum.
authors.affiliation: Institut Lavoisier, UMR 8180, Université de Versailles Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Pichon
authors.forename: Pierre
authors.initials: P
authors.lastname: Mialane
authors.forename: Jérôme
authors.initials: J
authors.lastname: Marrot
authors.forename: Claude
authors.initials: C
authors.lastname: Binet
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vimont
authors.forename: Arnaud
authors.initials: A
authors.lastname: Travert
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Lavalley
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D033362:Powder Diffraction; D011726:Pyridinium Compounds / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D014414:Tungsten / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D011726:Pyridinium Compounds; D014414:Tungsten