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Abstract: 2-Hydroxymethyl-pyridine with phenacyl bromide gives 3-hydroxy-3-phenyl-pyrido[2,1-c][1,4]dihydrooxazinium bromide (1). Its structure in crystal was determined by X-ray diffraction and confirmed by FTIR spectra and B3LYP calculations. In DMSO and D2O solutions, this compound exists in equilibrium mixtures with N-phenacyl-2-hydroxymethyl-pyridinium bromide (2). The equilibrium mixture was proved by FTIR, 1H, 13C and 15N NMR spectra. Correlations between the experimental 1H and 13C NMR chemical shifts for 1 and 2 and GIAO/B3LYP/6-31G(d,p) calculated magnetic isotropic shielding tensors (σ), δ exp=a+bσ cal, are reported. A good linear relationship between the experimental and calculated data was obtained only for carbons. [Copyright &y& Elsevier]

Abstract 2-(Quinuclidinium)-alkanocarboxylates co-crystallize with 2,6-dichloro-4-nitrophenol at the ratios 1:1 and 1:2 depending on the alkyl-chain lengths. The obtained complexes have been characterized by single-crystal X-ray diffraction, UV–vis, FTIR and NMR spectroscopy. The compounds 2-(quinuclidinium)-acetate and 2-(quinuclidinium)-propionate form complexes with 2,6-dichloro-4-nitrophenol at the stoichiometric ratio 1:2, while 2-(quinuclidinium)-butyrate and 2-(quinuclidinium)-valerate at ratio 1:1. Three crystal structures of compounds of these series were determined, but no single crystals of sufficient quality could be obtained of the 2-(quinuclidinium)-butyrate complex. The B3LYP/6-311++G(d,p) approach has been used to determine structures of their isolated molecules and to interpret the IR and UV–vis spectra. Diagrams of the HOMO and LUMO of molecules have been obtained. Graphical abstract Image 1 Highlights • Quiniclidinium-alkanocarboxylates form H B complexes with 2,6-dichloro-4-nitrophenol. • Lower homologues form molecular complexes at the 1:2 ratio. • Longer homologues form proton transfer 1:1 complexes. • Molecular structures were solved by X-ray diffraction and optimized by DFT methods. • UV–vis, FTIR and NMR spectra were measured. [ABSTRACT FROM AUTHOR]

The structures of 1,3-bis(3-hydroxymethylpyridinium)propane dibromide ( 1 ), 1,3-bis(3-hydroxymethylpyridinium)propane tetrabromozincate ( 2 ) and 1,3-bis(3-hydroxymethylpyridinium)propane tetrabromocuprate ( 3 ) have been studied by X-ray diffraction, DFT, FTIR, NMR and UV–vis methods. The crystal structures of three analogous compounds are significantly different: 1 is orthorhombic, space group Fdd 2, Z = 8, 2 is triclinic, space group P 1 ¯ , Z = 2 and 3 is monoclinic, space group C 2 /c , Z = 8. The bispyridinium dication in 1 lies on the special position on the 2-fold axis. Each 3-hydroxymethyl group forms an OH⋯Br hydrogen bond, and the dications combine into three-dimensional networks through numerous CH⋯Br bonds. The IR spectra of the dibromide of 1,3-bis(3-hydroxymethylpyridinium)propane ( 1 ) and its tetrabromometallates ( 2 and 3 ) were compared and their interpretation was confirmed by calculated spectra. UV–vis spectra for tetrabromocuprate salt ( 3 ) showed significant differences between solid-phase and water solution. [ABSTRACT FROM AUTHOR]