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Hydroxypyridazinone and pyrroledione rings condensation in the reactions of hydrazine hydrate with citraconic, 2,3-dimethylmaleic, succinic and cis-cyclohexanedicarboxylic anhydrides have been conducted in the HCl aqueous solution. The pyridazine-ring condensation yields products unexpected for these conditions. They have been identified by 1 H/ 13 C NMR and X-ray diffraction. The course of the reaction toward the five- and six-membered ring condensation strongly depends on methyl and other substituents in the anhydrides and in hydrazine. The obtained products indicate that the ring condensation is controlled by the molecular strains and steric hindrances between the substituents in anhydrides and pyridazinone products. The condensation of cyclic anhydrides with hydrazines has been reduced to one-step reaction and its yield significantly increased. [ABSTRACT FROM AUTHOR]

The structure of bis(4-trimethylammoniumbenzoate) hydroiodide hydrate 1 has been studied by X-ray diffraction, B3LYP/6–311G(d,p) calculations, FTIR, Raman and NMR spectroscopic techniques. The crystal is polar in monoclinic space group Cc. Two 4-trimethylammoniumbenzoate moieties are joined by a short and asymmetric hydrogen bond of 2.45(2) Å. Water molecules are gradually released from the structure, causing shifts in the position of iodine anions, which induces their disorder. The water molecule interacts with 4-trimethylammoniumbenzoate moiety and iodide anion via two O(3)–H(1)⋯O(1) and O(3)–H(2)⋯I(1) hydrogen bonds of lengths 2.70(3) and 3.51(1) Å. Hydrogen bonds in theoretically predicted structures of 2 and 3 (in vacuum), and 4 , 5 (in DMSO) optimized by the B3LYP/6-311G(d,p) approach are slightly longer than in crystal 1 . The FTIR spectrum of 1 shows a broad and intense absorption in the 1500–400 cm −1 region, typical of short hydrogen bonds assigned to the ν as (OHO) + γ (OHO) vibrations. The correlations between the experimental 13 C and 1 H chemical shifts ( δ exp ) of the investigated compound in DMSO and the GIAO/B3LYP/6-311G(d,p) magnetic isotropic shielding constants ( σ calc ) calculated by using the screening solvation model (COSMO) are linear, δ exp = a + b σ calc , and they well reproduce the experimental chemical shifts. [ABSTRACT FROM AUTHOR]

Abstract: The location of H-atoms sites in carboxylic-acid dimers has been related to the crystal environment. It has been shown that the H-sites are coupled to the orientation of carboxylic-acid groups. Consequently, the H-bonds can be strained and the H-atoms destabilized and disordered by the symmetric crystal environment of symmetric molecules. The coupling results in the O⋯O distance contraction by about 0.015Å in carboxylic acids with disordered H-atoms, this magnitude calculated from H-bonds strain being consistent with that observed in crystal structures. This strain analysis provides an easy method of locating the H-atoms in hydrogen bonds between carboxyl groups, verifying experimental data determined by X-ray diffraction, calculating the magnitudes of O⋯O distance contraction and molecular reorientations induced by the H-atoms disordering structural effects, and predicting properties related to the H-atom dynamics. The survey of carboxylic-acid structures corroborates the effects of the molecular environment on the H-sites and hydrogen-bond dimensions. [Copyright &y& Elsevier]

Abstract: Intermolecular interactions and the role of fluorine substitution have been investigated for a halogenated-ethane anesthetic. 2-Bromo-2-chloro-1,1,1-trifluoroethane, BrClCHCF3 (Halothane), has been in situ pressure frozen in a diamond anvil cell and its structure determined by single-crystal X-ray diffraction at 1.85(5)GPa/296K. Crystal is triclinic, space group . In this racemic structure the enantiomorphic molecules are substitutionally disordered at the same general positions in that way that bromine and chlorine atoms occupy the same site at the 50:50 ratio. Despite the fact that only the Br and Cl atoms are disordered, the crystal packing is dominated by halogen⋯halogen and halogen⋯hydrogen interactions. This X-ray diffraction study provides structural explanation of considerably increased vapor pressure of Halothane compared to its hydrogenated analogue. [Copyright &y& Elsevier]

Trimethyl(trifluoromethyl)silane, (CH3)3SiCF3, has been in situ pressure frozen in a diamond anvil cell and its structure determined at 0.90(5) GPa/296 K by single-crystal X-ray diffraction. The crystal is monoclinic, space group P21/m, with the molecules lying on crystallographic mirror planes. The CH3 and CF3 groups assume the fully staggered conformation. The 14-fold coordination scheme of the molecules is similar to those in (CH3)3SiCl polymorphs, but different from that in crystalline tetramethylsilane, (CH3)4Si (TMS). The longest Si—C bond length of 1.943(12) Å observed in the crystal structure has been documented. The shortest intermolecular contacts in the structure of pressure-frozen CF3Si(CH3)3 are observed between the hydrogen atoms, and those involving fluorine atoms are longer than sums of van der Waals’ radii. These structural features explain the facile cleavage of Si—CF3 bond for CF3 group transfer in organic reactions. [Copyright &y& Elsevier]

Abstract: The structure of 4-hydroxy-1-methylpiperidinium perchlorate has been characterized by X-ray diffraction, FTIR, Raman and NMR spectroscopies, and by DFT calculations. The crystals belong to orthorhombic Pbca group. The piperidine ring has a chair conformation with the hydroxyl and methyl groups in the equatorial positions. The hydroxyl group interacts by bifurcated O–H···O hydrogen bonds with the ClO4 − anion of 2.905(5) and 3.045(5)Å. Two optimized structures of the title compound have been calculated by the B3LYP/6–31G(d,p) approach. In one of them the anion is involved in the N+–H···O hydrogen bonds of 2.629Å, while in the other the anion interacts electrostatically with the N+ atom of the 4-hydroxy-1-methylpiperidinium cation. In aqueous solution two 4-hydroxy-1-methylpiperidinium perchlorates are in the conformational equilibrium. Their conformations are discussed on the basis of the NMR spectra. The solid state FTIR spectrum is consistent with the X-ray data. [Copyright &y& Elsevier]

The method of exhaustive methylation has been applied for investigating tautomeric stability and its temperature variation of 6-hydroxy-5-methyl-3-pyridazinone (1) and its N-phenyl derivative (2)—two model compounds chosen for studying tautomeric transformations of pyridazine medicinal drugs, either in the process of their production, or then their activity in the living tissue. The resulting N-methylated and O-methylated products were separated, and characterized by 1H NMR and X-ray diffraction. The methylation of 1 and 2 in the dimethyl sulfate as well as in its aqueous solution leads predominantly to the O-methylated forms, but the rising temperature favours the N-methylation. [Copyright &y& Elsevier]

A novel anhydrous 1:1 and 2:1 complexes of quinoline betaine (QB) with perchloric acid have been prepared and their structures determined by X-ray diffraction. The 1:1 complex betaine is protonated and the carboxylate group forms a hydrogen bond with the ClO4 ion: O⋯O distance is 2.820(3) A˚. In the 2:1 complex, the carboxylate group of a pair of QB molecules are bridged by a proton to form dimeric cation in non-planar configuration, [(QB)2H]+, featuring a very strong hydrogen bond of the length 2.453(3) A˚. The FTIR spectrum of the 1:1 complex shows a strong absorption at ca. 3100 cm−1 due to the νOH vibration. Broad and intense absorption in the 1500–400 cm−1 region in the spectrum of the 2:1 complex is typical for the very short hydrogen bonds. B3LYP calculations predict slightly shorter hydrogen bonds with different orientation of the ring vs. COOH group than these observed in crystals. [Copyright &y& Elsevier]

A novel and unique crystalline three-component complex was formed of 2-(1-piperidine)ethanol, p -hydroxybenzoic acid and water at the ratio 1:1:1. Its structure has been determined by single-crystal X-ray diffraction. This is an example of a hydrogen-bonded interaction between amino alcohol and benzoic acid molecules. Water acts as a bridge between molecules. The molecules are linked through medium-strong OH⋯O hydrogen bonds from 2.665(6) to 2.813(6) Å and NH⋯O one 2.744(5) Å in length. The molecular structure of 2-(1-piperidinium)ethanol p -hydroxybenzoate hydrate has been characterized by FTIR and Raman spectra and optimized at the B3LYP/6−311++G(d,p) level of theory. The potential energy distributions (PED) have been used to assign the vibrational spectra. Charge delocalization was analyzed using the natural bond orbital (NBO) methods. [ABSTRACT FROM AUTHOR]

The 1:1 complex of piperidine-4-carboxylic acid (isonipecotic acid, P4C) with 2,6-dichloro-4-nitrophenol (DCNP), has been investigated by single-crystal X-ray analysis, Raman and FTIR spectroscopy and theoretical calculations. The hydrogen-bonded-ion-pair complex is observed in the crystalline state with the O⋯H⋯OOC hydrogen bond of 2.453(16) Å. FTIR spectrum shows a broad absorption in the 1600–400 cm −1 region characteristic of very short OHO hydrogen bond, broken by the Evans holes. The complexes are joined through N H⋯O into a H-bonding network. The N H⋯O mode appears as a broad band in the range of 3100–2000 cm −1 . In the structure optimized at the B3LYP/6–311 + +G(d,p) level of theory the proton is transferred from DCNP to P4C, and molecules are joined through the O⋯HOOC hydrogen bond of 2.640 Å. The experimental and theoretical infrared spectra are discussed. Detail interpretation of the vibrational spectra has been carried out with the use of computed Potential Energy Distribution (PED). [ABSTRACT FROM AUTHOR]

( R / S )-Piperidine-3-carboxylic acid (P3C, nipecotic acid) forms a stable 1:1 hydrogen-bonded complex with 2,6-dichloro-4-nitrophenol (DCNP). Both, in crystal and in the optimized theoretically structure by the B3LYP/6-311 + +G(d,p) approach the proton is transferred from DCNP to P3C. The ( R ) and ( S )-stereoisomersic complexes of piperidinium-3-carboxylic acid 2,6-dichloro-4-nitrophenolate, P3C + H·DCNP − , aggregate into centrosymmetric cyclic dimers through the COOH⋯O − and N + H⋯ONO hydrogen bonds of 2.57(1) and 3.06(1) Å, respectively, which in turn are linked into a ladder-type cyclamer through the C H⋯Cl hydrogen bonds of 3.71(1) Å. The title compound is characterized by single-crystal X-ray analysis, Raman and FTIR spectroscopies. The structures of the complexes of the ratio 1:1 (monomer), 2:2 (dimer) and 4:4 (cyclamer) of P3C + H·DCNP − units are optimized by the B3LYP/6-311 + + G(d,p) approach and compared with the solid-state experimental structure. Detail interpretation of the vibrational spectra has been carried out by computing Potential Energy Distribution (PED). Charge delocalization has been analyzed using the Natural Bond Orbital (NBO) method. [ABSTRACT FROM AUTHOR]

Abstract: The ionophoric antibiotic lasalocid acid has been converted to a novel 6-bromohexyl ester (LASBR) and its structure has been determined in the crystal by X-ray diffraction and in solution by NMR and FT-IR methods. In the crystal two symmetry-independent LASBR molecules are present. The structure of LASBR in solution is slightly different because the strongest intramolecular C(1)Hogen bond in the pseudo-aromatic ring becomes partially broken and a new hydrogen bond between O(4)H and carbonyl group C(13)ed. LASBR forms complexes with Li+, Na+ and K+ cations of exclusively 1:1 stoichiometry. The structures of complexes have been studied and visualized using semi-empirical calculation based on results of spectrometric and spectroscopic investigation. It is demonstrated that in contrast to lasalocid acid the novel ester forms preferential complexes with Li+ cation. [Copyright &y& Elsevier]

Abstract: 4-Nitrophenyl[bis(benzylthio)]methane was synthesized and used in structural study by X-ray diffraction combined with NMR and spectrophotometric method. In the crystal structure the molecule assumes the conformation where the acidic H-atom is difficult to access due to sterical hindrances of three surrounding phenyls. The acidic properties of 4-nitrophenyl[bis(benzylthio)]methane have been compared and discussed with the analogous disulfonyl carbon acid 4-nitrophenyl[bis(benzylsulfonyl)]methane. [Copyright &y& Elsevier]

• Structure of 8 - hydroxyquinoline betaine monohydrate was solved by X-ray. • The one proton of disordered water molecules is shared between two half-occupied sides. • Three broad bands classify the FTIR spectrum as the ABC type. • PED are used to assign the bands in the vibrational spectrum. • Hirshfeld surface, Mulliken atomic charges, MEP, HOMO-LUMO were computed. • The assignment of 1H and 13C resonance signals are based on the 2D measurements. Molecular structure and properties of 8-hydroxyquinoline betaine monohydrate (1-carboxymethyl-8-hydroxyquinolinium inert salt monohydrate) were studied by X-ray diffraction, DFT calculations, FTIR and NMR spectra. In the crystals, 8-hydroxyquinoline betaine and water are bonded by an intermolecular and asymmetric COO···H 2 O hydrogen bond of 2.782(3) Å. The water molecules are disordered so that one of the proton is shared between two half occupied sites. The hydroxyl group of quinoline is bonded to the neighboring molecule by the O−H···OOC hydrogen bond of 2.571(3) Å. The molecular geometry, Hirshfeld surface, Mulliken atomic charge distribution, molecular electrostatic potential, frontier molecular orbitals, vibrational wavenumbers, magnetic isotropic shielding constants were determined using the density functional theory (DFT/B3LYP) with 6–311++G(d,p) basis set. The FTIR spectrum shows a characteristic ABC structure, typical of medium-short hydrogen bonds. The potential energy distribution (PED) was used to assign the bands in the vibrational spectrum. 1H and 13C NMR spectra were analyzed. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Intermolecular interactions in a synthesized C-acid, 4-nitrophenyl[bis(ethylsulfonyl)]methane have been analysed and its structure determined by X-ray diffraction. The molecular packing in the crystal is governed by CH…O. The dimensions of the hydrogen bonds and the shortest non-bonded distances are also determined. The possible implications in the formation of the hydrogen bonded complexes with the strong organic bases are also discussed. [Copyright &y& Elsevier]

Abstract: The 2:2 hydrogen-bonded complex between Kemp’s triacid (KTA) and 1,1,3,3-tetramethylguanidine (TMG) has been synthesised and studied by X-ray diffraction and by FT-IR spectroscopy. Cocrystals of KTA–TMG belong to the monoclinic system and crystallize in the space group is P2 1 with a =10.5017(3)Å, b =7.9504(3)Å, c =11.8910(4)Å, β =104.004(4)° and Z =2. The ring of the KTA monoanion molecule exhibits a chair conformation with all three carboxylic groups in the axial positions and all three methyl groups in the equatorial positions. In the crystal of the complex, cooperative systems involving inter- and intra-molecular hydrogen bonds are formed. In the solid state two protonated TMG molecules and two deprotonated KTA molecules form a dimer in which three-dimensional hydrogen-bonded networks are found. [Copyright &y& Elsevier]

Abstract: Crystal structure of monensin A rubidium salt dihydrate, [Rb(C36H61O11)·2H2O], has been studied by X-ray diffraction, FT-IR spectroscopy and PM5 semiempirical methods. The crystal space group is P212121 with a =12.6153(7), b =16.4841(10), c =19.4840(12) and Z =4. The Rb–O bond lengths are between 2.788(7) and 2.901(6)Å. The carboxyl group of monensin A is deprotonated and engaged in two intramolecular O(11)–H···O(1) of 2.52(1)Å and O(10)–H···O(2) of 2.60(1)Å hydrogen bonds with hydroxyl groups, accompanied with formation of a pseudo-cyclic structure. This structure is stabilised by the coordination of the Rb+ cation by oxygen atoms. Two water molecules are involved in the weak intermolecular hydrogen bond between the different species forming a supramolecule. The IR spectrum of the crystal is consistent with the results obtained by the X-ray study and provides spectroscopic evidence for the complex formation. The calculated structure and the structural parameters of the monensin A rubidium salt are comparable with those determined by the X-ray study. [Copyright &y& Elsevier]

Abstract: The 2:2 hydrogen-bonded cocrystals between Kemp’s triacid (KTA) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) have been prepared and characterized by X-ray diffraction and FT-IR spectroscopy. Cocrystals of KTA–TBD (2:2) belong to the monoclinic system and its space group is P21/n with a =12.3016(7)Å, b =11.8130(6)Å, c =14.3279(7)Å, β =101.15(1)° and Z =4. The KTA mono anion ring has a chair conformation with all three carboxylic groups in the axial positions and all three CH3 groups in the equatorial positions. In the crystal of the complex the cooperative systems involving inter- and intra-molecular hydrogen bonds are formed. In the solid state two protonated TBD molecules and two deprotonated KTA molecules form a dimer in which three-dimensional hydrogen-bonded networks have been found. The nature of these hydrogen bonds is well reflected by the proton vibrations in the FT-IR spectra of the crystal studied. The negative ion mode ESI-MS spectrum of the cocrystal indicated the existence of a KTA monoanion. The fragmentation pathways of this anion are discussed. [Copyright &y& Elsevier]

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: Azido-tetrazolo tautomeric conversions have been investigated by NMR, X-ray and semiempirical calculations in a series of new 7(8)-methylated azolopyridazines. The transannular effects of the triazole- and tetrazole-ring fusion with pyridazine have been compared, and the thermodynamic equilibrium of the 7- to 8-methyl conversions of the 6-azido-7(8)-methyltetrazolopyridazines monitored in the function of temperature by 1H NMR shifts of the pyridazine hydrogens. General rules governing the azido-tetrazolo conversions in azolopyridazines have been formulated and based on the molecular structure and strains induced in the pyridazine ring by its substituents. [Copyright &y& Elsevier]

Crystals of the Schiff base derivative of gossypol with 3,6,9-trioxa-decylamine were examined using X-ray diffraction, FT-IR and CPMAS spectroscopy. The Schiff base crystallizes as a racemate in the space group C2/c with a=24.390(5), b=12.026(2), c=14.810(3) A˚, β=102.78(3)°, and Z=4. The results of the FT-IR, and CPMAS study of the crystals are in agreement with the X-ray data. The FT-IR spectrum of the crystals shows that the OH groups at position 1,1′ and 6,6′ as well as the N16–H proton are involved in weak intermolecular and intramolecular hydrogen bonds, respectively. The FTIR and CP-MAS spectral behaviour is in agreement with the crystallographic results demonstrating the existence of the enamine-enamine tautomeric form of the Schiff base studied. [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]

The complex of 2-(hydroxymethyl)-1-methyl-piperidine [2-(1-methyl-piperidine)-methanol] (MPMe) and p -hydroxybenzoic acid (HBA) crystallizes as a hydrate. HBA interacts through the OH···O and NH···O hydrogen bonds with MPMe. The water mediated hydrogen-bonded bridge molecules MPMe and HBA. The structure of 2-(hydroxymethyl)-1-methyl-piperidinium p -hydroxybenzoate hydrate has been characterized by X-ray diffraction, FTIR and NMR spectroscopy and optimized at the B3LYP/6-311++G(d,p) level of theory. The potential energy distributions, PED, have been used to assign the vibrational spectra. The GIAO/B3LYP/6-311++G(d,p) calculated magnetic isotropic shielding constants have been used to interpret the chemical shifts in the 1 H and 13 C NMR spectra. [ABSTRACT FROM AUTHOR]

The molecular structure of 1,2-di(3-hydroxymethylpyridinium)ethane dibromide ( 1 ) has been characterized by X-ray diffraction, B3LYP/6-311++G(d,p) calculations, FTIR, Raman and NMR spectra. The crystals are monoclinic, space group C2/c . 1,2-Di(3-hydroxymethylpyridinium)ethane dication and hydrogen-bonded bromide anions in crystals are located at the inversion center. The both CH 2 OH groups are engaged in two equal length hydrogen bonds with bromide anions. Two structures ( 2 ) and ( 3 ) were optimized at the B3LYP/6-311++G(d,p) level of theory. The optimized complex ( 2) resembles the crystal structure, while complex ( 3 ) is preferred energetically. The O⋯Br − hydrogen bonds distances are: 3.289(2) Å in crystals ( 1 ), but in the optimized structures ( 2 ) and ( 3 ) they are 3.303 Å and 3.461 Å, respectively. The investigated complex is additionally stabilized by the N + ⋯Br − electrostatic attractions. The potential energy distributions (PED) were used for the assignments of IR and Raman frequencies in the experimental and calculated spectra of the title compound. The FTIR spectrum of ( 1 ) is consistent with the X-ray results. Interpretation of the 1 H and 13 C NMR spectra in DMSO- d 6 has been based on 2D experiments. The calculated GIAO/B3LYP/6-311++G(d,p) magnetic shielding constants have been used to predict 1 H and 13 C chemical shifts for the optimized structures of ( 2 ) and ( 3 ). [ABSTRACT FROM AUTHOR]

The structure of the complex of dimethylphenyl betaine (DMPB) with dichloroacetic acid (DCA) ( 1 ) has been investigated by X-ray diffraction, FTIR and Raman spectroscopy, and B3LYP/6-311 + + G(d,p) calculations. The crystal is monoclinic, space group P 2 1 . The acid is connected with betaine through the O H⋯O hydrogen bond of 2.480(2) Å. In the optimized structure the short, asymmetric O⋯O distance is 2.491 Å. FTIR spectrum shows a broad absorption in the 1500–400 cm −1 region characteristic of very short O H⋯O hydrogen bond caused by Fermi resonance between νOH and overtones of δOH and γOH. In the Raman spectrum this broad absorption is not observed. The potential energy distributions (PED) were used for the assignments of IR and Raman frequencies in the experimental and calculated spectra. The FTIR and Raman spectra of the crystal complex are consistent with the X-ray results. [ABSTRACT FROM AUTHOR]

The 1:2 complex ( 1 ) of dimethylphenyl betaine (DMPB) with two molecules of 2,6-dichloro-4-nitro-phenol (DCNP) was prepared and characterized by X-ray diffraction, B3LYP/6-311++G(d,p) and B3LYP-D3/6-311++G(d,p)calculations, FTIR and NMR spectroscopies. The crystal is monoclinic, space group P 2 1 / c with Z = 4. The protons at the oxygen atoms of phenols are bonded to each oxygen atoms of the DMPB carboxylate group by two nonequivalent H-bonds with the O H⋯O distances of 2.473(5) and 2.688(4) Å. Both H-bonds in the optimized structures 2 (in vacuum), 3 (in DMSO solution) and dispersion-correlated functional (D3) 4 (in vacuum) are comparable and are slightly shorter than O(6) H(O6)⋯O(2) in the crystal. The FTIR spectrum of 1 shows a broad absorption in the 3400–2000 cm −1 region corresponding to a longer hydrogen bond and a broad absorption in the 1800–500 cm −1 region caused by the shorter H-bond. The relations between the experimental 13 C and 1 H chemical shifts ( δ exp ) of the investigated compound 1 in DMSO solution and GIAO/B3LYP/6-311++G(d,p) magnetic isotropic shielding constants ( σ calc ) obtained by using the screening solvation model (COSMO) for 3 are linear and reproduce well the experimental chemical shifts described by the equation: δ exp = a + b σ calc . [ABSTRACT FROM AUTHOR]

Abstract: A complex between a new N-phenylamide of monensin A (M-AM1) and sodium chloride has been synthesised and studied by X-ray diffraction and FT-IR spectroscopy. The crystal structure of the complex between M-AM1 and sodium chloride with acetonitrile was examined using X-ray diffraction and discussed in detail. Its structure is stabilised by coordination of the Na+ cation with oxygen atoms. The Na–O bond lengths are between 2.382(2) and 2.562(2)Å. The chloride anion is involved in a weak intermolecular hydrogen bond between different species forming a supramolecule. The ESI-MS spectra indicate that the amide forms stable complexes of exclusively 1:1 stoichiometry with Na+ cations. The FT-IR spectrum of the crystal is consistent with the results obtained by the X-ray study and provides spectroscopic evidence for the complex formation. Due to its specific structural properties N-phenylamide of monensin A efficiently binds sodium chloride. The result of the PM5 semiempirical calculation is in agreement with the spectroscopic data and allows visualisation of the structure of the M-AM1–Na+ complex. The new amide of monensin A has been additionally tested in view of its antimicrobial properties. It shows great activity towards some strains of Gram-positive bacteria (MIC=6.25–12.5μg/ml). [Copyright &y& Elsevier]

Abstract: The crystal structure of the 1:1 complex of lasalocid acid with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) has been studied by X-ray diffraction, FT-IR spectroscopy and 1H NMR. The crystal space group is P212121 with a =11.401(2)Å, b =13.393(3)Å, c =30.063(6)Å and Z =4. In the crystal of the complex a cooperative system involving inter and intramolecular hydrogen bonds is formed. The protonated TBD and two ends of the lasalocid acid anion are hydrogen bonded. These NH⋯O hydrogen bonds are, with a length of 2.907(9) and 2.930(8)Å, relatively long. In the crystal structure the oxygen atoms of the carboxylate group are involved in three intramolecular hydrogen bonds of different length: O(4)O(1) of 2.848(7)Å, O(8)O(1) of 2.938(6)Å and O(3) O(2) of 2.460(8)Å. In chloroform and acetonitrile solutions the crystal structure of the 1:1 complex is only partially preserved, and additionally a new structure, in which the ketone carbonyl group is hydrogen bonded, is formed. The structures have been modeled using the semiempirical PM5 method. [Copyright &y& Elsevier]

• 5-(Quinolinium)-valeric acid bromide hydrates form centrosymmetric and asymmetric dimers. • Water is a bridge between 5-(quinolinium)-valeric acid cations and bromide anions. • The DFT calculations were used to optimize isolated structures of monomer and dimer. • PED are used to assign the bands in the vibrational spectrum. • The NBO, MEP and QTAIM methods were used to characterize the optimized structures. The molecular structure and properties of 5-(quinolinium)-valeric acid bromide monohydrate are characterized by X-ray diffraction, B3LYP/6–311++G(d,p) calculations, FTIR and NMR spectra. Two molecules of this compound are hydrogen bonded through two water molecules and two bromide anions into centrosymmetric dimers, which are arranged in a strongly anisotropic layered structure. The structures of monomer and dimer of the title complex are optimized at the B3LYP/6–311++G(d,p) level of theory. The conformations of the valeric acid unit in the crystalline monohydrate and in isolated molecules (monohydrates and anhydrous forms) are compared. The experimental and theoretical infrared spectra are discussed. The FTIR spectrum shows an absorption in the 3500–2700 cm−1 region attributed to the νCOOH···OH 2 and νBr−···H 2 O. The potential energy distributions (PED) are used to assign bands in the IR spectrum of the monomer. The 1H and 13C NMR chemical shifts are assigned by two-dimensional techniques, COSY, HSQC and HMBC. Charge delocalization is analyzed using the natural bond orbital (NBO) method and it is shown in molecular electrostatic potential (MEP) maps. The bent conformations of the computed structures are characterized by the QTAIM method. Image, graphical abstract [ABSTRACT FROM AUTHOR]

N- Methylpyrrolidine betaine (N- carboxymethyl- N- methyl-pyrrolidinium, inner salt, MPRB) cocrystallizes with p -hydroxybenzoic acid (HBA) at the 1:1 ratio. The complex is characterized by single-crystal X-ray diffraction, FTIR and NMR spectra. The pyrrolidinium ring adopts an envelope conformation with the methyl group in axial and the carboxymethyl substituent in the equatorial positions. In the cocrystal the COO⋯HO and COO⋯HOOC hydrogen bonds are of 2.574 (4) and 2.586 (4) Å, respectively. The molecular geometry, Hirshfeld surface, natural bond orbitals (NBO), molecular electrostatic potential (MEP), vibrational wavenumbers, magnetic isotropic shielding constants were performed using the density functional theory (DFT/B3LYP) with 6–311++G (d,p) basis set. The molecular structures of isolated 1:1 and 1:2 complexes were optimized. The potential energy distribution (PED) of the IR vibrational modes were used to assign the bands in the IR spectrum. Diagrams of the HOMO and LUMO of components and complex are presented. Theoretical and experimental results are in a good agreement. Image 1 • The 1:1 complex of N-methylpyrrolidine betaine with p -hydroxybenzoic acid was prepared. • Structure of complexes were characterized by X-ray diffraction, FTIR and NMR spectra. • The structures of 1:1 and 1:2 complexes were optimized by the B3LYP/6-311++G(d,p) approach. • The molecules are linked through the OH∙∙∙OOC and COOH∙∙∙OOC hydrogen-bonds. • The IR and NMR experimental and computed spectra were discussed. [ABSTRACT FROM AUTHOR]