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1.
Eric Busseron Dr. Camille Romuald Frédéric Coutrot Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(33):10062-10073
High‐yield, straightforward synthesis of two‐ and three‐station [2]rotaxane molecular machines based on an anilinium, a triazolium, and a mono‐ or disubstituted pyridinium amide station is reported. In the case of the pH‐sensitive two‐station molecular machines, large‐amplitude movement of the macrocycle occurred. However, the presence of an intermediate third station led, after deprotonation of the anilinium station, and depending on the substitution of the pyridinium amide, either to exclusive localization of the macrocycle around the triazolium station or to oscillatory shuttling of the macrocycle between the triazolium and monosubstituted pyridinium amide station. Variable‐temperature 1H NMR investigation of the oscillating system was performed in CD2Cl2. The exchange between the two stations proved to be fast on the NMR timescale for all considered temperatures (298–193 K). Interestingly, decreasing the temperature displaced the equilibrium between the two translational isomers until a unique location of the macrocycle around the monosubstituted pyridinium amide station was reached. Thermodynamic constants K were evaluated at each temperature: the thermodynamic parameters ΔH and ΔS were extracted from a Van′t Hoff plot, and provided the Gibbs energy ΔG. Arrhenius and Eyring plots afforded kinetic parameters, namely, energies of activation Ea, enthalpies of activation ΔH≠, and entropies of activation ΔS≠. The ΔG values deduced from kinetic parameters match very well with the ΔG values determined from thermodynamic parameters. In addition, whereas signal coalescence of pyridinium hydrogen atoms located next to the amide bond was observed at 205 K in the oscillating rotaxane and at 203 K in the two‐station rotaxane with a unique location of the macrocycle around the pyridinium amide, no separation of 1H NMR signals of the considered hydrogen atoms was seen in the corresponding nonencapsulated thread. It is suggested that the macrocycle acts as a molecular brake for the rotation of the pyridinium–amide bond when it interacts by hydrogen bonding with both the amide NH and the pyridinium hydrogen atoms at the same time. 相似文献
2.
R. Jagan D. Sathya K. Sivakumar 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(5):374-380
In the salt 1‐methylpiperazine‐1,4‐diium bis(dihydrogen phosphate), C5H13N22+·2H2PO4−, (I), and the solvated salt 2‐(pyridin‐2‐yl)pyridinium dihydrogen phosphate–orthophosphoric acid (1/1), C10H9N2+·H2PO4−·H3PO4, (II), the formation of O—H...O and N—H...O hydrogen bonds between the dihydrogen phosphate (H2PO4−) anions and the cations constructs a three‐ and two‐dimensional anionic–cationic network, respectively. In (I), the self‐assembly of H2PO4− anions forms a two‐dimensional pseudo‐honeycomb‐like supramolecular architecture along the (010) plane. 1‐Methylpiperazine‐1,4‐diium cations are trapped between the (010) anionic layers through three N—H...O hydrogen bonds. In solvated salt (II), the self‐assembly of H2PO4− anions forms a two‐dimensional supramolecular architecture with open channels projecting along the [001] direction. The 2‐(pyridin‐2‐yl)pyridinium cations are trapped between the open channels by N—H...O and C—H...O hydrogen bonds. From a study of previously reported structures, dihydrogen phosphate anions show a supramolecular flexibility depending on the nature of the cations. The dihydrogen phosphate anion may be suitable for the design of the host lattice for host–guest supramolecular systems. 相似文献
3.
Jonathan D. Webb Véronique S. Laberge Stephen J. Geier Douglas W. Stephan Prof. Dr. Cathleen M. Crudden Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(16):4895-4902
We report herein that the reaction between a series of Hantzsch’s ester analogues 1 a – d with the Lewis acidic species B(C6F5)3 results in facile transfer of hydride to boron. The main products of this reaction are pyridinium borohydride salts 2 a – d , which are obtained in high to moderate yields. The N‐substituted substrates (N‐Me, N‐Ph) reacted in high yield 90–98 % and the connectivity of the products were confirmed by an X‐ray crystallographic analysis of the N‐Me borohydride salt 2 a . Unsubstituted Hanztsch’s ester 1 a reacted less effectively generating only 60 % of the corresponding borohydride salt, with the balance of the material sequestered as the ester‐bound Lewis acid–base adduct 3 a . Formation of the Lewis acid–base adduct could be minimized by increasing the steric bulk about the ester groups as in 1 d . The connectivity of the carbonyl‐bound adduct was confirmed by an X‐ray crystallographic analysis of 3 e the product of the reaction of methyl ketone 1 e with B(C6F5)3. We also explored the generation of these pyridinium salts by employing frustrated Lewis pair methodology. However, the reaction of mixtures of the corresponding pyridine and B(C6F5)3 with hydrogen gas only resulted in formation of trace amounts of the pyridinium borohydride, along with the Lewis acid–base adduct of the starting material and B(C6F5)3. The 1,2‐dihydropyridine adduct was the final product of this reaction. This was ascribed to the low basicity of the pyridine nitrogen and the complicating formation of an ester bound Lewis acid–base adduct. 相似文献
4.
A Reversible Proton Relay Process Mediated by Hydrogen‐Bonding Interactions in [FeFe]Hydrogenase Modeling
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Kai‐Ti Chu Dr. Yu‐Chiao Liu Yi‐Lan Huang Cheng‐Huey Hsu Dr. Gene‐Hsiang Lee Prof. Dr. Ming‐Hsi Chiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):10978-10982
A reversible and temperature‐dependent proton‐relay process is demonstrated for a Fe2 complex possessing a terminal thiolate in the presence of nitrogen‐based acids. The terminal sulfur site (St) of the complex forms a hydrogen‐bond interaction with N,N‐dimethylanilinium acid at 183 K. The Fe2 core, instead, is protonated to generate a bridging hydride at 298 K. Reversibility is observed for the tautomerization between the hydrogen‐bonded pair and the Fe–hydride species. X‐ray structural analysis of the hydrogen‐bonded species at 193 K reveals a short N(H)???St contact. Employment of pyridinium acid also results in similar behavior, with reversible proton–hydride interconversion. DFT investigation of the proton‐transfer pathways indicates that the pKa value of the hydrogen‐bonded species is enhanced by 3.2 pKa units when the temperature is decreased from 298 K to 183 K. 相似文献
5.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(9):682-687
To enable a comparison between a C—H…X hydrogen bond and a halogen bond, the structures of two fluorous‐substituted pyridinium iodide salts have been determined. 4‐[(2,2‐Difluoroethoxy)methyl]pyridinium iodide, C8H10F2NO+·I−, (1), has a –CH2OCH2CF2H substituent at the para position of the pyridinium ring and 4‐[(3‐chloro‐2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium iodide, C9H9ClF4NO+·I−, (2), has a –CH2OCH2CF2CF2Cl substituent at the para position of the pyridinium ring. In salt (1), the iodide anion is involved in one N—H…I and three C—H…I hydrogen bonds, which, together with C—H…F hydrogen bonds, link the cations and anions into a three‐dimensional network. For salt (2), the iodide anion is involved in one N—H…I hydrogen bond, two C—H…I hydrogen bonds and one C—Cl…I halogen bond; additional C—H…F and C—F…F interactions link the cations and anions into a three‐dimensional arrangement. 相似文献
6.
Jos J. Campos‐Gaxiola Susana P. Arredondo Rea Ramn Corral Higuera Herbert Hpfl Adriana Cruz Enríquez 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(1):48-52
Two organic–inorganic hybrid compounds have been prepared by the combination of the 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium cation with perhalometallate anions to give 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium tetrachloridocobaltate(II), (C12H12N2)[CoCl4], (I), and 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium tetrachloridozincate(II), (C12H12N2)[ZnCl4], (II). The compounds have been structurally characterized by single‐crystal X‐ray diffraction analysis, showing the formation of a three‐dimensional network through X—H...ClnM− (X = C, N+; n = 1, 2; M = CoII, ZnII) hydrogen‐bonding interactions and π–π stacking interactions. The title compounds were also characterized by FT–IR spectroscopy and thermogravimetric analysis (TGA). 相似文献
7.
The cooperativity between the dihydrogen bond and the N???HC hydrogen bond in LiH–(HCN)n (n=2 and 3) complexes is investigated at the MP2 level of theory. The bond lengths, dipole moments, and energies are analyzed. It is demonstrated that synergetic effects are present in the complexes. The cooperativity contribution of the dihydrogen bond is smaller than that of the N???HC hydrogen bond. The three‐body energy in systems involving different types of hydrogen bonds is larger than that in the same hydrogen‐bonded systems. NBO analyses indicate that orbital interaction, charge transfer, and bond polarization are mainly responsible for the cooperativity between the two types of hydrogen bonds. 相似文献
8.
Marc Renom‐Carrasco Piotr Gajewski Dr. Luca Pignataro Prof. Johannes G. de Vries Prof. Umberto Piarulli Prof. Cesare Gennari Dr. Laurent Lefort 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9528-9532
The use of an equivalent amount of an organic base leads to high enantiomeric excess in the asymmetric hydrogenation of N‐benzylated 3‐substituted pyridinium salts into the corresponding piperidines. Indeed, in the presence of Et3N, a Rh‐JosiPhos catalyst reduced a range of pyridinium salts with ee values up to 90 %. The role of the base was elucidated with a mechanistic study involving the isolation of the various reaction intermediates and isotopic labeling experiments. Additionally, this study provided some evidence for an enantiodetermining step involving a dihydropyridine intermediate. 相似文献
9.
Norman Lu Mani Alagesan Chi-Liang Ho Rong-Jyun Wei Chih-Chieh Kung Jung-Shan Chang Yuh-Sheng Wen Ling-Kang Liu 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(12):1007-1011
It is possible that fluorous compounds could be utilized as directing forces in crystal engineering for applications in materials chemistry or catalysis. Although numerous fluorous compounds have been used for various applications, their structures in the solid state remains a lively matter for debate. The reaction of 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridine with HX (X = I or Cl) yielded new fluorous ponytailed pyridinium halide salts, namely 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium iodide, C8H9F3NO+·I−, (1), and 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium chloride, C8H9F3NO+·Cl−, (2), which were characterized by IR spectroscopy, multinuclei (1H, 13C and 19F) NMR spectroscopy and single‐crystal X‐ray diffraction. Structure analysis showed that there are two types of hydrogen bonds, namely N—H…X and C—H…X. The iodide anion in salt (1) is hydrogen bonded to three 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations in the crystal packing, while the chloride ion in salt (2) is involved in six hydrogen bonds to five 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations, which is attributed to the smaller size and reduced polarizability of the chloride ion compared to the iodide ion. In the IR spectra, the pyridinium N—H stretching band for salt (1) exhibited a blue shift compared with that of salt (2). 相似文献
10.
Orhan Büyükgüngr Mustafa OdabasÛoglu 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(3):o105-o106
Two cyclic eight‐membered hydrogen‐bonded rings exist in the title compound, 2C5H7N2+·C4H2O42−, involving the 2‐aminopyridinium and maleate ions. The dihedral angle between the two pyridinium rings hydrogen bonded to the maleate ion is 74.80 (4)°. The maleate anion lies on a twofold axis and is linked to the pyridinium cations by intermolecular N—H⃛O hydrogen bonds. The heterocycle is fully protonated, which enables amino–imino tautomerization. 相似文献
11.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(8):593-599
The salts 3‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium saccharinate, C9H10F4NO+·C7H4NO3S−, (1), and 3‐[(2,2,3,3,3‐pentafluoropropoxy)methyl]pyridinium saccharinate, C9H9F5NO+·C7H4NO3S−, (2), i.e. saccharinate (or 1,1‐dioxo‐1λ6,2‐benzothiazol‐3‐olate) salts of pyridinium with –CH2OCH2CF2CF2H and –CH2OCH2CF2CF3meta substituents, respectively, were investigated crystallographically in order to compare their fluorine‐related weak interactions in the solid state. Both salts demonstrate a stable synthon formed by the pyridinium cation and the saccharinate anion, in which a seven‐membered ring reveals a double hydrogen‐bonding pattern. The twist between the pyridinium plane and the saccharinate plane in (2) is 21.26 (8)° and that in (1) is 8.03 (6)°. Both salts also show stacks of alternating cation–anion π‐interactions. The layer distances, calculated from the centroid of the saccharinate plane to the neighbouring pyridinium planes, above and below, are 3.406 (2) and 3.517 (2) Å in (1), and 3.409 (3) and 3.458 (3) Å in (2). 相似文献
12.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(4):343-349
Neutralization of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridine with hydrohalo acids HX (X = Cl and Br) yielded the pyridinium salts 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium chloride, C9H10F4NO+·Cl−, (1), and 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium bromide, C9H10F4NO+·Br−, (2), both carrying a fluorous side chain at the para position of the pyridinium ring. Single‐crystal X‐ray diffraction techniques revealed that (1) and (2) are isomorphous. The halide anions accept four hydrogen bonds from N—H, ortho‐C—H and CF2—H groups. Two cations and two anions form a centrosymmetric dimeric building block, utilizing complimentary N—H…X …H—Csp 3 connections. These dimers are further crosslinked, utilizing another complimentary Csp 2—H…X …H—Csp 2 connection. The pyridinium rings are π‐stacked, forming columns running parallel to the a axis that make angles of ca 44–45° with the normal to the pyridinium plane. There are also supramolecular C—H…F—C interactions, namely bifurcated C—H…F and bifurcated C—F…H interactions; additionally, one type II C—F…F—C halogen bond has been observed. 相似文献
13.
Sin C. James Yvonne G. Lawson Nicholas C. Norman A. Guy Orpen Michael J. Quayle 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):427-429
Two pentahalo(N‐donor)bismuthate(III) salts, bis[hydrogen bis(4‐picoline)(1+)] pentabromo(4‐picoline‐N)bismuthate(III), (C12H15N2)2[BiBr5(C6H7N)], (I), and bis(pyridinium) pentachloro(pyridine‐N)bismuthate(III), (C5H6N)2[BiCl5(C5H5N)], (II), are described which show modest deviations from octahedral geometry at bismuth. In (I), the cations comprise two 4‐picoline molecules sharing a proton and in (II), pyridinium cations are present. The anion in (I) has twofold and that in (II) has mirror crystallographic symmetry. Both structures show a layered packing formed by the anions with the cations between the layers. Ring–ring interactions seem important in (I), whilst in (II), N/C—H?Cl—Bi hydrogen bonding is abundant. 相似文献
14.
John Giantsidis Mark M. Turnbull 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):334-335
The title compound, 2‐amino‐5‐carboxypyridinium chloride, C6H7N2O2+·Cl?, was isolated from a 1 M HCl aqueous solution containing 2‐amino‐5‐cyanopyridine. The structure is held together by extensive hydrogen bonding between the chloride ions and the carboxylic acid, amino and pyridinium H atoms. The molecules pack as sheets, with the sheets at a distance of 3.21 (3) Å from one another. 相似文献
15.
Propane pyrolysis is studied in the presence and the absence of dihydrogen between 743 and 803 K, in the propane pressure range 10–100 Torr, and at 20–254 Torr dihydrogen pressure. In unpacked Pyrex reactors, dihydrogen accelerates propane dehydrogenation and demethanation. The reaction is modeled by a conventional homogeneous free‐radical chain mechanism. Propane pyrolysis is strongly inhibited by the walls of reactors packed with stainless steel, zirconium, or palladium foils. Adding dihydrogen to propane still increases the rates of product formation. The reaction in these packed reactors is modeled by the kinetic scheme proposed for the homogeneous reaction and by the heterogeneous process H. ⇄ ½H2 (w2)(−w2) of chain termination and initiation. In the absence of dihydrogen, step (−w2) is negligible and precise values of uptake coefficients of hydrogen atoms are obtained at 773 K: 0.31 for stainless steel 0.10 for zirconium 0.05 for palladium In the presence of dihydrogen, steps (w2) and (−:w2) are instantaneously at equilibrium. The latter system should be useful to study any reaction of hydrogen atoms in the temperature range. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 340–364, 2000 相似文献
16.
Jonathan C. Parrish Rudong Shan Edward E. Knaus Michael N. G. James 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):107-109
This analysis establishes the rotameric orientation of the pyridyl‐ring N atom of the title compound, C17H21N3O4·0.5C6H6, as antiperiplanar (ap) to the 1,4‐dihydropyridine H‐4, the absence of an intramolecular hydrogen bond between the 1,4‐dihydropyridine NH and the pyridyl‐N atom, and the unusual planarity of the 1,4‐dihydropyridine ring. 相似文献
17.
P. Balamurugan R. Jagan K. Sivakumar 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(3):o109-o113
The title compounds, 2‐chloroanilinium dihydrogen phosphate (2CADHP) and 4‐chloroanilinium dihydrogen phosphate (4CADHP), both C6H7NCl+·H2PO4−, form two‐dimensional supramolecular organic–inorganic hybrid frameworks. In 2CADHP, the dihydrogen phosphate anions form a double‐stranded anionic chain generated parallel to the [010] direction through O—H...O hydrogen bonds, whereas in 4CADHP they form a two‐dimensional supramolecular net extending parallel to the crystallographic (001) plane into which the cations are linked through strong N—H...O hydrogen bonds. 相似文献
18.
Graham Smith Urs D. Wermuth 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(1):o5-o10
The 1:1 proton‐transfer compounds of l ‐tartaric acid with 3‐aminopyridine [3‐aminopyridinium hydrogen (2R,3R)‐tartrate dihydrate, C5H7N2+·C4H5O6−·2H2O, (I)], pyridine‐3‐carboxylic acid (nicotinic acid) [anhydrous 3‐carboxypyridinium hydrogen (2R,3R)‐tartrate, C6H6NO2+·C4H5O6−, (II)] and pyridine‐2‐carboxylic acid [2‐carboxypyridinium hydrogen (2R,3R)‐tartrate monohydrate, C6H6NO2+·C4H5O6−·H2O, (III)] have been determined. In (I) and (II), there is a direct pyridinium–carboxyl N+—H...O hydrogen‐bonding interaction, four‐centred in (II), giving conjoint cyclic R12(5) associations. In contrast, the N—H...O association in (III) is with a water O‐atom acceptor, which provides links to separate tartrate anions through Ohydroxy acceptors. All three compounds have the head‐to‐tail C(7) hydrogen‐bonded chain substructures commonly associated with 1:1 proton‐transfer hydrogen tartrate salts. These chains are extended into two‐dimensional sheets which, in hydrates (I) and (III) additionally involve the solvent water molecules. Three‐dimensional hydrogen‐bonded structures are generated via crosslinking through the associative functional groups of the substituted pyridinium cations. In the sheet struture of (I), both water molecules act as donors and acceptors in interactions with separate carboxyl and hydroxy O‐atom acceptors of the primary tartrate chains, closing conjoint cyclic R44(8), R34(11) and R33(12) associations. Also, in (II) and (III) there are strong cation carboxyl–carboxyl O—H...O hydrogen bonds [O...O = 2.5387 (17) Å in (II) and 2.441 (3) Å in (III)], which in (II) form part of a cyclic R22(6) inter‐sheet association. This series of heteroaromatic Lewis base–hydrogen l ‐tartrate salts provides further examples of molecular assembly facilitated by the presence of the classical two‐dimensional hydrogen‐bonded hydrogen tartrate or hydrogen tartrate–water sheet substructures which are expanded into three‐dimensional frameworks via peripheral cation bifunctional substituent‐group crosslinking interactions. 相似文献
19.
Takeo Fukunaga Setsuo Kashino Hiroyuki Ishida 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o718-o722
Tartronic acid forms a hydrogen‐bonded complex, C5H5NO·C3H4O5, (I), with 2‐pyridone, while it forms acid salts, namely 3‐hydroxypyridinium hydrogen tartronate, (II), and 4‐hydroxypyridinium hydrogen tartronate, (III), both C5H6NO+·C3H3O5−, with 3‐hydroxypyridine and 4‐hydroxypyridine, respectively. In (I), the pyridone molecules and the acid molecules form R(8) and R(10) hydrogen‐bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N—H⋯O and O—H⋯O hydrogen bonds to form a hydrogen‐bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxylate groups in (II) and (III). 相似文献
20.
Jan Janczak Genivaldo Julio Perptuo 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(6):o330-o334
Crystals of the title compounds, namely 1‐(diaminomethylene)thiouron‐1‐ium perchlorate, C2H7N4S+·ClO4−, 1‐(diaminomethylene)thiouron‐1‐ium hydrogen sulfate, C2H7N4S+·HSO4−, 1‐(diaminomethylene)thiouron‐1‐ium dihydrogen phosphate, C2H7N4S+·H2PO4−, and its isomorphic relative 1‐(diaminomethylene)thiouron‐1‐ium dihydrogen arsenate, C2H7N4S+·H2AsO4−, are built up from a nonplanar 1‐(diaminomethylene)thiouron‐1‐ium cation and the respective anion linked together via N—H...O hydrogen bonds. Both arms of the cation are planar, but they are twisted with respect to one another around the central N atom. Ionic and extensive hydrogen‐bonding interactions join oppositely charged units into layers in the perchlorate, double layers in the hydrogen sulfate, and a three‐dimensional network in the dihydrogen phosphate and dihydrogen arsenate salts. This work demonstrates the usefulness of 1‐(diaminomethylene)thiourea in crystal engineering for the formation of supramolecular networks with acids. 相似文献