π-Bond cooperativity and anticooperativity effects in resonance-assisted hydrogen bonds (RAHBs)

2006 ◽  
Vol 62 (5) ◽  
pp. 850-863 ◽  
Author(s):  
Valerio Bertolasi ◽  
Loretta Pretto ◽  
Gastone Gilli ◽  
Paola Gilli
Keyword(s):  
Hydrogen Bonds ◽  
Local Defect ◽  
Bond Polarity ◽  
X Ray ◽  
Extensive Analysis ◽  
Cooperativity Effects ◽  
Structural Database ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Bond cooperativity effects, which are typical of `resonant' chains or rings of π-conjugated hydrocarbons, can also occur in hydrogen-bonded systems in the form of σ-bond and π-bond cooperativity or anticooperativity. σ-Bond cooperativity is associated with the long chains of O—H...O bonds in water and alcohols while σ-bond anticooperativity occurs when the cooperative chain is interrupted by a local defect reversing the bond polarity. π-Bond cooperativity is the driving force controlling resonance-assisted hydrogen bonds (RAHBs), while π-bond anticooperativity has never been considered so far and is investigated here by studying couples of hydrogen-bonded β-enolone and/or β-enaminone six-membered rings fused through a common C=O or C—C bond. The effect is studied by X-ray crystal structure determination of five compounds [(2Z)-1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione enol (1), (2Z)-1-(2-hydroxy-5-chlorophenyl)-3-phenyl-1,3-propanedione enol (2), (2Z)-1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione enol (3), (2Z)-1-(2-hydroxy-4-methyl-5-chlorophenyl)-3-phenyl-1,3-propanedione enol (4) and dimethyl(2E)-3-hydroxy-2-{[(4-chlorophenyl)amino]carbonyl}pent-2-enedioate (5)] and by extensive analysis of related fragments found in the CSD (Cambridge Structural Database). It is shown that fusion through the C=O bond is always anticooperative and such to weaken the symmetric O—H...O...H—O and N—H...O...H—N bonds formed, but not the asymmetric O—H...O...H—N bond. Fusion through the C—C bond may produce either cooperative or anticooperative hydrogen bonds, the former being more stable than the latter and giving rise to a unique resonance-assisted ten-membered ring running all around the two fused six-membered rings, which can be considered a type of tautomerism never described before.

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Synthesis, crystal structure and biological activity of copper(II) complex with 4-nitro-3-pyrazolecarboxylic ligand

2020 ◽  
Vol 85 (7) ◽  
pp. 885-895
Author(s):  
Milica Kosovic ◽  
Sladjana Novakovic ◽  
Zeljko Jacimovic ◽  
Nedeljko Latinovic ◽  
Nada Markovic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biological Activity ◽  
Octahedral Coordination ◽  
Biological Research ◽  
Coordination Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Database ◽  
Commercial Fungicide

The reaction of 4-nitro-3-pyrazolecarboxylic acid and Cu(OAc)2?H2O in ethanol resulted in a new coordination compound [Cu2(4-nitro-3- -pzc)2(H2O)6]2H2O (4nitro-3pzc = 4-nitro-3-pyrazolecarboxylate). The compound was investigated by means of single-crystal X-ray diffraction and infrared spectroscopy. The biological activity of the complex was also tested. In the crystal structure of [Cu2(4nitro-3-pzc)2(H2O)6]2H2O, the Cu(II) ion is in a distorted [4+2] octahedral coordination due to the Jan?Teller effect. A survey of the Cambridge Structural Database showed that the octahedral coordination geometry is generally rare for pyrazole-bridged Cu(II) complexes. In the case of Cu(II) complexes with the 3-pyrazolecarboxylato ligands, no complexes with a similar octahedral coordination geometry have been reported. Biological research based on determination of the inhibition effect of the commercial fungicide Cabrio top and the newly synthesized complex on Ph. viticola were performed using the phytosanitary method.

Dimer oder nicht dimer, das ist hier die Frage: Zwei benachbarte I3–--Ionen eingeschlossen in Hohlr¨aumen einer komplexen Wirtsstruktur

2010 ◽  
Vol 65 (12) ◽  
pp. 1462-1466 ◽  
Author(s):  
Michaela K. Meyer ◽  
Jürgen Graf ◽  
Guido J. Reiß
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Dimensional Network ◽  
Oder Nicht ◽  
Bonding Interaction ◽  
Hydrogen Bonded

[Me(HO)2P-(CH2)10-P(O)OHMe]2[I3]2・MeHO(O)P-(CH2)10-P(O)OHMe (1) was synthesized and characterized by IR, Raman and NMR spectroscopy. Its structure was determined by singlecrystal X-ray diffraction (T = 100 K; space group P1̄). The structure consists of decane-1,10-diyl-bis- (methylphosphinic acid) molecules and the analogous mono-protonated cations in a ratio 1:2 connected with each other by strong O-H···O hydrogen bonds to form a two-dimensional network. Between these hydrogen-bonded layers, there are elongated cavities each containing two triiodide anions. The intermolecular I· · · I distance of the two enclosed triiodide anions is 3.6317(4) Å and should be considered as an interhalogen bonding interaction.

Conformational analysis: crystallographic, molecular mechanics and quantum chemical studies of C—H...O hydrogen bonding in the flexible bis(nosylate) derivative of catechol

2004 ◽  
Vol 60 (5) ◽  
pp. 598-608 ◽  
Author(s):  
Orde Quentin Munro ◽  
Lynette Mariah
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Lattice ◽  
Molecular Mechanics ◽  
Quantum Chemical ◽  
Critical Role ◽  
Crystalline Solid ◽  
Molecular Architecture ◽  
X Ray ◽  
Hydrogen Bonded

The single-crystal X-ray diffraction analysis of 2-{[(4-nitrophenoxy)sulfonyl]oxy}phenyl 4-nitrophenyl sulfate (4) reveals that an interesting intermolecular or extended structure (a one-dimensional hydrogen-bonded polymer) is formed because of pairs of intermolecular (aryl)C—H...O(nitro) hydrogen bonds between the C 2 symmetry monomer units. The axis of the hydrogen-bonded polymer runs co-linear with the [101] face diagonal of the monoclinic unit cell. Molecular mechanics calculations using a modified version of the MM+ force field and a random conformational search algorithm have been used to locate the important low-energy in vacuo conformations of (4). The MM-calculated conformation of (4) that most closely matches the X-ray structure lies some 26.5 kJ mol−1 higher in energy than the global minimum-energy conformation, consistent with the notion that the crystallographically observed molecular architecture of (4) is a local energy minimum in the absence of its crystal lattice environment. Since the X-ray conformation of (4) was correctly calculated only when all of the neighbouring molecules in the crystal lattice were included in the simulation, hydrogen bonding and other non-bonded interactions in the crystal lattice clearly dictate the experimentally observed conformation of (4). Quantum chemical calculations (AM1 method) confirm the critical role played by the intermolecular (aryl)C—H...O(nitro) hydrogen bonds in controlling the crystallographically observed conformation of (4) and show that self-recognition in this system by hydrogen bonding is favoured on electrostatic grounds. Collectively, the molecular simulations suggest that because the lowest-energy molecular conformation of (4) does not permit the formation of an extended hydrogen-bonded `supramolecular' structure, it is not the preferred conformation in the crystalline solid state.

Crystal and Molecular Structure of 4-Arylhexahydro-1H,3H-pyrido[1,2-c]pyrimidine-1,3-dione Derivatives

2002 ◽  
Vol 57 (11) ◽  
pp. 1315-1319 ◽  
Author(s):  
Irena Wolska ◽  
Franciszek Herold
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Phenyl Ring ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
Saturated Ring ◽  
Centrosymmetric Dimers

The X-ray crystal structure determination of 4-(2-methylphenyl)hexahydro-1H,3H-pyrido[ 1,2-c]pyrimidine-1,3-dione (2) and 4-(3-methylphenyl)hexahydro-1H,3H-pyrido[1,2-c]- pyrimidine-1,3-dione (3) is reported. The crystal structures show the formation of centrosymmetric dimers via intermolecular N-H···O hydrogen bonds. The saturated ring adopts a slightly distorted halfchair conformation in both 2 and 3. In either compound the planar phenyl ring is twisted with respect to the pyrimidine-1,3-dione fragment.

scholarly journals Isostructural Inorganic–Organic Piperazine-1,4-diium Chlorido- and Bromidoantimonate(III) Monohydrates: Octahedral Distortions and Hydrogen Bonds

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1361
Author(s):  
Maciej Bujak ◽  
Dawid Siodłak
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Ligand Exchange ◽  
Structural Parameters ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Hydrogen Bond Interactions ◽  
Hybrid Crystals ◽  
Structural Database ◽  
Hydrogen Bonded Systems

Halogenidoantimonate(III) monohydrates of the (C4H12N2)[SbX5]·H2O (X = Cl, 1 or Br, 2) formula, crystallizing in the same monoclinic space group of P21/n, are isostructural, with an isostructurality index close to 99%. The single crystal X-ray diffraction data do not show any indication of phase transition in cooling these crystals from room temperature to 85 K. Both hybrid crystals are built up from [SbX6]3– octahedra that are joined together by a common edge forming isolated bioctahedral [Sb2X10]4– units, piperazine-1,4-diium (C4H12N2)2+ cations and water of crystallization molecules. These structural components are joined together by related but somewhat different O/N/C–H···X and N–H···O hydrogen bonded systems. The evolution of structural parameters, notably the secondary Sb–X bonds along with the associated X/Sb–Sb/X–X/Sb angles and O/N/C–H···X hydrogen bonds, as a function of ligand exchange and temperature, along with their influence on the irregularity of [SbX6]3– octahedra, was determined. The comparison of packing features and hydrogen bond parameters, additionally supported by the Hirshfeld surface analysis and data retrieved from the Cambridge Structural Database, demonstrates the hierarchy and importance of hydrogen bond interactions that influence the irregularity of single [SbX6]3– units.

scholarly journals The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

2010 ◽  
Vol 6 ◽  
Author(s):  
Kari Raatikainen ◽  
Massimo Cametti ◽  
Kari Rissanen
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystal ◽  
Halogen Bonding ◽  
Relative Strength ◽  
Supramolecular Interactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Database ◽  
Non Covalent Interactions ◽  
Covalent Interactions

The series of haloanilinium and halopyridinium salts: 4-IPhNH3Cl (1), 4-IPhNH3Br (5), 4-IPhNH3H2PO4 (6), 4-ClPhNH3H2PO4 (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH3Cl (3, CURGOL), 4-FPhNH3Cl (4, ANLCLA), 4-BrPhNH3H2PO4, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Based on the X-ray data it was possible to highlight the balance between non-covalent forces acting in these systems, where the relative strength of the halogen bonding C–X···A− (X = I, Br or Cl) and the ratio between the halogen and hydrogen bonds [C–X···A− : D–H···A−] varied across the series.

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