Theoretical study of molecular interactions of sulfur ylide with HF, HCN, and HN3

The molecular interactions between sulfur ylide (SY) and HX molecules (X = F, CN, and N₃) were investigated using the MP2 method at 6-311++G(2d,2p) basis set. Three different patterns including non-classical hydrogen bond (HB) H···C and classical HB H···X were found for complex formation between SY and HX molecules. Stability of the H···C type complexes are greater than H···X complexes. Quantum theories of atoms in molecules, natural bond orbitals, and energy decomposition analysis methods have been applied to analyze the intermolecular interactions. Good correlations have been found between the interaction energies (SE), the second-order perturbation energy E ⁽²⁾ and the charge transfer qCT in the studied systems.     

Theoretical study of molecular interactions of sulfur ylide with HSX (X = F, Cl, and Br) molecules

The molecular interactions between sulfur ylide (SY) and HSX molecules (X = F, Cl and Br) were investigated using the MP2 method with the 6-311++G (2d, 2p) basis set. The SY (CH₂=SH₂) have two reactive sites: CH₂ (denoted as C-interaction) and SH₂ (S-interaction) that both could interact with three atoms of HSX molecules. The results show that S···C, X···C, and H···C interactions (C-interactions) is preference over the X···S, H···S, and H···X interactions. Quantum theories of atoms in molecules and natural bond orbitals methods have been applied to analyze the intermolecular interactions. Good correlations have been found between the interaction energies, the second-order perturbation energies E⁽²⁾, and the charge transfer qCT in the studied systems.     

Synthesis and crystal structure of 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate

The compound 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate has been prepared and characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. The crystal and molecular structure were further confirmed using single crystal X-ray diffraction. The crystal structure has been found to be stabilized by intermolecular C–H···O interaction generating bifurcated hydrogen bonds whereas the C–H···N interactions generate chain of molecules. The intramolecular N–H···N hydrogen bond forms a ring with S(7) graph-set motif.     

Theoretical study of bifurcated hydrogen bonding effects on the 1J(N,H), 1hJ(N,H), 2hJ(N,N) couplings and 1H, 15N shieldings in model pyrroles

According to the density functional theory calculations, the X···H···N (X?N, O) intramolecular bifurcated (three‐centered) hydrogen bond with one hydrogen donor and two hydrogen acceptors causes a significant decrease of the ^1hJ(N,H) and ^2hJ(N,N) coupling constants across the N? H···N hydrogen bond and an increase of the ¹J(N,H) coupling constant across the N? H covalent bond in the 2,5‐disubsituted pyrroles. This occurs due to a weakening of the N? H···N hydrogen bridge resulting in a lengthening of the N···H distance and a decrease of the hydrogen bond angle at the bifurcated hydrogen bond formation. The gauge‐independent atomic orbital calculations of the shielding constants suggest that a weakening of the N? H···N hydrogen bridge in case of the three‐centered hydrogen bond yields a shielding of the bridge proton and deshielding of the acceptor nitrogen atom. The atoms‐in‐molecules analysis shows that an attenuation of the ^1hJ(N,H) and ^2hJ(N,N) couplings in the compounds with bifurcated hydrogen bond is connected with a decrease of the electron density ρ_H···N at the hydrogen bond critical point and Laplacian of this electron density ?²ρ_H···N. The natural bond orbital analysis suggests that the additional N? H···X interaction partly inhibits the charge transfer from the nitrogen lone pair to the σ*_{N? H} antibonding orbital across hydrogen bond weakening of the ^1hJ(N,H) and ^2hJ(N,N) trans‐hydrogen bond couplings through Fermi‐contact mechanism. An increase of the nitrogen s‐character percentage of the N? H bond in consequence of the bifurcated hydrogen bonding leads to an increase of the ¹J(N,H) coupling constant across the N? H covalent bond and deshielding of the hydrogen donor nitrogen atom. Copyright © 2010 John Wiley & Sons, Ltd.     

A computational study of 1:1 and 1:2 complexes of nitryl halides (O2NX) with HCN and HNC

Quantum calculations at the MP2/cc-pVTZ have been used to examine 1:1 and 1:2 complexes between O₂NX (X = Cl, Br) with HCN and HNC moieties. The interaction of the lone pair of the HCN(HNC) with the σ-hole and π-hole of O₂NX molecules and hydrogen bonding between lone pairs of X and O of O₂NX with H of HCN and HNC have been considered in 1:1 complexes. The 1:1 complexes can easily be differentiated using the stretching frequency of the N–X bond. Thus, those complexes with σ-hole and H···O₂NX interactions show a blue shift of the N-X bond stretching while a red shift is observed in the complexes along the π-hole and H···XNO₂ interactions. In the 1:2 complexes, the cooperative and diminutive energetic effects have been analyzed using the many-body interaction energies. The nature of the interactions has been characterized with the Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) methodologies. Stabilization energies of 1:1 and 1:2 complexes including the variation of the zero-point vibrational energy (ΔZPVE) are in the range 3–9 kJ mol^?1 and 21–40 kJ mol^?1, respectively.     

Nature of MoH···I bonds in Cp2Mo(L)H···I‐C≡C‐R Complexes (L=H,CN, PPh2, C(CH3)3; R=NO2, Cl,Br, H,OH, CH3, NH2)

The nature of the MoH···I bond in Cp₂Mo(L)H···I‐C≡C‐R (L= H, CN, PPh₂, C(CH₃)₃; R=NO₂, Cl, Br, H, OH, CH₃, NH₂) was investigated using electrostatic potential analysis, topological analysis of the electron density, energy decomposition analysis and natural bond orbital analysis. The calculated results show that MoH···I interactions in the title complexes belong to halogen‐hydride bond, which is similar to halogen bonds, not hydrogen bonds. Different to the classical halogen bonds, the directionality of MoH···I bond is low; Although electrostatic interaction is dorminant, the orbital interactions also play important roles in this kind of halogen bond, and steric interactions are weak; the strength of H···I bond can tuned by the most positive electrostatic potential of the I atom. As the electron‐withdrawing ability of the R substituent in the alkyne increases, the electrostatic potential maximum of the I atom increases, which enhances the strength of the H···I halogen bond, as well as the electron transfer.     

Crystal Structures of [Cu2(bpy)2(H2O)(OH)2(SO4)]·4H2O and [Cu(bpy)(H2O)2]SO4 with bpy = 2, 2′‐Bipyridine

Two sulfato Cu^II complexes [Cu₂(bpy)₂(H₂O)(OH)₂(SO₄)]· 4H₂O ( 1 ) and [Cu(bpy)(H₂O)₂]SO₄ ( 2 ) were synthesized and structurally characterized by single crystal X—ray diffraction. Complex 1 consists of the asymmetric dinuclear [Cu₂(bpy)₂(H₂O)(OH)₂(SO₄)] complex molecules and hydrogen bonded H₂O molecules. Within the dinuclear molecules, the Cu atoms are in square pyramidal geometries, where the equatorial sites are occupied by two N atoms of one bpy ligand and two O atoms of different μ₂—OH groups and the apical position by one aqua ligand or one sulfato group. Through intermolecular O—H···O and C—H···O hydrogen bonds and intermolecular π—π stacking interactions, the dinuclear complex molecules are assembled into layers, between which the hydrogen bonded H₂O molecules are located. The Cu atoms in 2 are octahedrally coordinated by two N atoms of one bpy ligand and four O atoms of two H₂O molecules and two sulfato groups with the sulfato O atoms at the trans positions and are bridged by sulfato groups into ¹[Cu(bpy)(H₂O)₂(SO₄)_2/2] chains. Through the interchain π—π stacking interactions and interchain C—H···O hydrogen bonds, the resulting chains are assembled into bi—chains, which are further interlinked into layers by O—H···O hydrogen bonds between adjacent bichains.     

On the Correlation between the Blue Shift of Hydrogen Bonding and the Proton Donor-Proton Acceptor Distance

It is demonstrated that in all types of hydrogen bonds (X—H…Y) there is a balance between the long-range attractive orbital interactions and short-range Pauli/nucleus repulsions. When the proton acceptor approaches the proton donor from distance, the hydrogen bonding energy becomes more negative at relatively large distance, goes through a minimum, and then starts to become less negative when the short-range repulsive forces come into effect.Meanwhile, the X--H bond length increases at relatively large distances, goes through a maximum and starts to shorten when the short-range repulsive forces come into effect. Whether the hydrogen bond is red or blue shifted is dictated by the energy minimum position. If at the energy minimum position the X—H bond length is shorter than that for the free monomer, the hydrogen bond is blue shifted and vice versa. Further studies demonstrate that the recent report about the correlation of C—H bond lengths with proton donor-acceptor distance in F3C—H…OH2 and F3C—H…Cl^- is not fully correct because the authors conducted an inappropriate comparison. Furthermore, it is shown for the first time that the Pauli/nucleus repulsion theory is applicable to the blue-shifted hydrogen bonds in the X—H…π complexes and the blue-shifted lithium bonds in the X—Li…Y complexes.     

Hydrogen bonding characterization of XH2NH2···HNO(X = B,Al, Ga) complexes: A theoretical investigation

The complexes of XH₂NH₂···HNO(X = B, Al, Ga) are characterized as head to tail with hydrogen bonding interactions. The structural characteristics can be confirmed by atoms in molecules (AIM) analysis, which also provide comparisons of hydrogen bonds strengths. The calculated interaction energies at G2MP2 level show that stability of complexes decrease as BH₂NH₂···HNO > AlH₂NH₂···HNO > GaH₂NH₂···HNO. On the basis of the vibrational frequencies calculations, there are red‐shifts for ν(X1? H) and blue‐shifts for ν(N? H) in the complexes on dihydrogen bonding formations (X1? H···H? N). On hydrogen bonding formations (N? H···O), there are red‐shifts for ν(N? H) compared to the monomers. Natural bond orbital (NBO) analysis is used to discuss the reasons for the ν(X1? H) and ν(N? H) stretching vibrational shifts by hyperconjugation, electron density redistribution, and rehybridization. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Time-Dependent Density Functional Theory Study on Hydrogen and Dihydrogen Bonding in Electronically Excited State of 2-Pyridone–Borane–Trimethylamine Cluster

In this work, the intermolecular dihydrogen and hydrogen bonding interactions in electronically excited states of a 2-pyridone (2PY)–borane–trimethylamine (BTMA) cluster have been theoretically studied using time-dependent density functional theory method. Our computational results show that the S₁ state of 2PY–BTMA cluster is a locally excited state, in which only 2PY moiety is electronically excited. The theoretical infrared (IR) spectra of the 2PY–BTMA cluster demonstrate that the N–H stretching vibrational mode is slightly blue-shifted upon the electronic excitation. Moreover, the computed IR spectrum of the 2PY–BTMA cluster exhibits no carbonyl character due to the extension of the C=O bond length in the S₁ state. However, the N–H bond is shortened slightly upon photoexcitation. At the same time, the H···H and H···O distances are obviously lengthened in the S₁ sate by comparison with those in ground state. In addition, the electron density of the carbonyl oxygen is diminished due to the electronic excitation. Consequently, the proton acceptor ability of carbonyl oxygen is decreased in the electronic excited state. As a result, it is demonstrated that the intermolecular dihydrogen and hydrogen bonds are significantly weakened in the electronically excited state.     

O–H···C hydrogen bond in the methane–water complex

Quantum chemical calculations were performed at different levels of theory (SCF, DFT, MP2, and CCSD(T)) to determine the geometry and electronic structure of the HOH···CH₄ complex formed by water and methane molecules, in which water is a proton donor and methane carbon (sp³) is an acceptor. The charge distribution on the atoms of the complex was analyzed by the CHelpG method and Hirshfeld population analysis; both methods revealed the transfer of electron charge from methane to water. According to the natural bond orbital (NBO) analysis data, the charge transfer upon complexation is caused by the interaction between the σ orbital of the axial С–H bond of methane directed along the line of the O–H···C hydrogen bridge and the antibonding σ* orbital of the О–H bond of the water molecule. Topological analysis of electron density in the HOH···CH₄ complex by the AIM method showed that the parameters of the critical point of the bond between hydrogen and acceptor (carbon atom) for the O–H···C interaction are typical for Н-bonded systems (the magnitude of electron density at the critical point of the bond, the sign and value of the Laplacian). It was concluded that the intermolecular interaction in the complex can be defined as an Н bond of O–H···σ(С–H) type, whose energy was found to be 0.9 kcal/mol in MP2/aug-cc-pVQZ calculations including the basis set superposition error (BSSE).     

Studies of two different types of intramolecular C–H···F–C interactions from polyfluorinated diiodometal(II) diimine complexes

The X‐ray crystal structures of the polyfluorinated complexes [5,5′‐bis(HCF₂CF₂CF₂CF₂CH₂OCH₂)‐2,2′‐bpy]MI₂ ( 55‐8F‐PtI ₂ and 55‐8F‐PdI ₂ where M = Pt and Pd, respectively) were obtained. These two structures are found to show not only two different types of intramolecular, six‐membered cyclic C–H···F–C interactions (F₂C–H···F–C and HC–H···F–C) as important structural features but also alternating fluorinated and non‐fluorinated layers. The F₂C–H···F–C interactions, which are close to the metal core, are much better structurally characterized in this type of complexes with fluorous ponytails at the 5,5′ positions than those previously reported at the 4,4′ positions. The molecular planes of (bpy)MI₂ are extended by self‐matching, using two C–H···I hydrogen bonds and one C–H···F–C blue‐shifting hydrogen bond. The F₂C–H···F–C hydrogen bonds interact at the supramolecular level such that one polyfluorinated ponytail of the title compounds is transoid without an intramolecular C–H···F–C interaction, while the other polyfluorinated ponytail is cisoid with an intramolecular C–H···F–C interaction. Why one ponytail is cisoidal while the other is transoidal will be explained. Furthermore, the second type of C–H···F–C interactions involving the methylene H atom has been identified for the first time. In addition, these two metal structures are studied by density functional theory (DFT).     

A comparative study of some lithium and hydrogen‐bonded complexes: Ab initio and QTAIM studies

The nature of the interactions of cyanide with lithium and hydrogen halides was investigated using ab initio calculations and topological analysis of electron density. The computed properties of the lithium‐bonded complexes RCN···LiX (R = H, F, Cl, Br, C?CH, CH?CH₂, CH₃, C₂H₅; X = Cl, Br) were compared with those of corresponding hydrogen‐bonded complexes RCN···HX. The results show that both types of intermolecular interactions are “closed‐shell” noncovalent interactions. The effect of substitution on the interaction energy and electron density at the bond critical points of the lithium and hydrogen bonding interactions is similar. In comparison, the interaction energies of lithium‐bonded complexes are more negative than those of hydrogen‐bonded counterparts. The electrostatic interaction plays a more important role in the lithium bond than in the hydrogen bond. On complex formation, the net charge and energy of the Li atom decrease and the atomic volume increases, while the net charge and energy of the H atom increase and the atomic volume decreases. © 2013 Wiley Periodicals, Inc.     

Ein lamellarer Schichtverband auf der Grundlage von Wasserstoffbrücken und π‐Stapelung: Kristallstruktur des Lithiumkomplexes [Li{C6H4(SO2)2N}(H2O)3] und ein Vergleich mit anderen Metall(I)‐benzol‐1, 2‐di(sulfonyl)amiden

The title complex, obtained by treating ortho‐benzenedisulfonimide (HZ) with LiOH in aqueous solution, has been characterized by low‐temperature X‐ray diffraction (triclinic, space group P&1macr;, Z' = 1). The lithium cation is bonded to one sulfonyl oxygen atom and three water molecules in a distorted tetrahedral configuration [Li‐O 189.3(3)‐201.2(3) pm, O‐Li‐O 98.5(2)‐123.2(2)?]. The zero‐dimensional [Li(Z)(H₂O)₃] complexes, which display an intramolecular O(W)‐H···O hydrogen bond, are cross‐linked via five O(W)‐H···O/N/O(W) interactions and a remarkably short C‐H···O bond (H···O 217 pm, C‐H···O 170?) to form a two‐dimensional assembly comprising an internal polar lamella of metal cations, (SO₂)₂N groups and water molecules, and hydrophobic peripheral regions consisting of protruding benzo groups. In the packing, alternate carbocycles drawn from adjacent layers set up a π‐stacking array of parallel aromatic rings (intercentroid distances 349 and 369 pm, cycle spacings 331 and 336 pm). In a short survey, the currently known crystal packings of seven M^IZ · n H₂O (n ≥ 0) complexes are examined and compared.     

Polysulfonylamine. CLXXVIII Onium‐Salze des Benzol‐1,2‐di(sulfonyl)amins (HZ): Eine zweite Kristallform des Ammonium‐Salzes NH4Z·H2O und Kristallstruktur des Bis(triphenylphosphoranyliden)ammonium‐Salzes [Ph3PNPPh3]Z

Polysulfonylamines. CLXXVIII. Onium Salts of Benzene‐1,2‐di(sulfonyl)amine (HZ): A Second Crystal Form of the Ammonium Salt NH₄Z·H₂O and Crystal Structure of the Bis(triphenylphosphoranylidene)ammonium Salt [Ph₃PNPPh₃]Z A dimorphic form of NH₄Z·H₂O, where Z^? is N‐deprotonated ortho‐benzenedisulfonimide, has been obtained and structurally characterized (previously known form 1A : monoclinic, P2₁/c, Z′ = 1; new polymorph 1B : monoclinic, P2₁/n, Z′ = 1). Both structures are dominated by an abundance of classical hydrogen bonds N⁺–H/O–H···O=S/OH₂, whereby the anionic N^? function does not act as an acceptor. The major difference between the dimorphs arises from the topology of the hydrogen bond network, which is two‐dimensional in 1A , leading to a packing of discrete lamellar layers, but three‐dimensional in 1B . Moreover, the latter network is reinforced by a set of weak C–H··O/N hydrogen bonds, whereas the layered structure of 1A displays only one independent C–H···O bond, providing a link between adjacent layers. The compound [Ph₃PNPPh₃]Z ( 2 , monoclinic, P2₁/c, Z′ = 1) is the first structurally authenticated example of an ionic Z^? derivative in which the cation contains neither metal bonding sites nor strong hydrogen bond donors. This structure exhibits columns of anions, surrounded by four parallel columns of cations, giving a square array. The large cations are associated into a three‐dimensional framework via weak C–H···C(π) interactions and an offset face‐to‐face phenyl interaction, while the anions occupy tunnels in this framework and are extensively bonded to the surrounding cations by C–H···O/N^? hydrogen bonds and C–H···C(π) interactions.     

Intermolecular complexes of nido-C<Subscript>2</Subscript>B<Subscript>3</Subscript>H<Subscript>7</Subscript> with HF and LiH molecules: the theoretical studies,bonding properties and natural bond orbital (NBO) analysis

The changes in stabilization energy upon the formation of intermolecular hydrogen, dihydrogen and lithium bond complexes between C₂B₃H₇, LiH and HF have been investigated using MP2 method with aug-cc-pVDZ basis set. The interaction of HF with nido-C₂B₃H₇ could occur through the formation of B–H^?δ···^+δH–F, C–H^+δ···F^?δ–H and B–C···H–F classical and non-classical hydrogen bonds. The B–C bonds in backbone of the C₂B₃H₇ as electron donor interact with σ* orbital of HF as electron acceptor. Also interaction of LiH with nido-C₂B₃H₇ resulted in B–C···Li–H and B–H···LiH lithium bonds as well as C–H···H–Li dihydrogen bond complexes. In some of these complexes, LiH interacts with B–C bonds. Results are indicating that more stable complexes belong to interaction of HF and LiH with backbone of the nido-C₂B₃H₇. The AIM and NBO methods were used to analyze the intermolecular interactions; also the electron density at the bond critical point and the charge transfer of obtained complexes were studied.     

Supramolecular solid-state structure,potential energy surfaces and evaluation of antiproliferative effect of 2-benzothiazolylhydrazone derivatives in vitro

The in situ condensation reaction of 2-hydrazinobenzothiazole with salicylaldehyde, 3,4-dihydroxybenzaldehyde, 2,4-dihydroxybenzaldehyde, 2,5-dihydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 2-hydroxy-1-naphthaldehyde, 2-methoxy-1-naphthaldehyde, 4-methoxy-1-naphthaldehyde and 6-methoxy-2-naphthaldehyde produced 9 hydrazone Schiff bases (L1–L9, respectively) which were identified and characterized by elemental analysis, IR and NMR spectroscopy. The crystal and molecular structures of four Schiff bases (L1, L7–L9) have been determined by the single-crystal X-ray diffraction method confirming the imino form of L1 and the amino tautomeric form of L7–L9 compounds. Molecular structure analysis also confirmed that reported compounds are E-isomers relative to exo C = N imino bond. The N_hydrazino–H group of amino tautomers forms N_hydrazino–H···N_thiazolyl intermolecular hydrogen bonds shaping molecules into R ₂ ² (8) rings, while imino tautomer of L1 forms C(4) infinite helical chains via N_thiazolyl–H···N_hydrazino type of intermolecular hydrogen bond. The methoxy group (L7–L9) further shaped these primary supramolecular synthons into different supramolecular arrangements via C–H···O, C–H···N and C–H···S intermolecular hydrogen bonds. The role of aryl substituents in the shaping and stabilization of supramolecular architectures of L1, L7–L9 is supported by quantum chemical calculations. Strong antiproliferative effects on tumor cells and cytotoxic effects on fibroblasts are shown for all ligands L1–L9 with exception of L6 and L7 that had no effect on fibroblast cells.     

An insight into CH···N hydrogen bond and stability of the complexes formed by trihalomethanes with ammonia and its monohalogenated derivatives

A theoretical study of the C?H···N hydrogen bond in the interactions of trihalomethanes CHX₃ (X = F, Cl, Br) with ammonia and its halogen derivatives NH₂Y (Y = F, Cl, Br) has been carried out thoroughly. The complexes are quite stable, and their stability increases in going from CHF₃ to CHCl₃ then to CHBr₃ when Y keeps unchanged. With the same CHX₃ proton donor, enhancement of the gas phase basicity of NH₂Y strengthens stability of the CHX₃···NH₂Y complex. The C?H···N hydrogen bond strength is directly proportional to the increase of proton affinity (PA) at N site of NH₂Y and the decrease of deprotonation enthalpy (DPE) of C?H bond in CHX₃. The CHF₃ primarily appears to favor blue shift while the red‐shift is referred to the CHBr₃. The blue‐ or red‐shift of CHCl₃ strongly depends on PA at N site of NH₂Y. We suggest the ratio of DPE/PA as a factor to predict which type of hydrogen bond is observed upon complexation. The SAPT2+ results show that all C?H···N interactions in the complexes are electrostatically driven regardless of the type of hydrogen bond, between 48% and 61% of the total attractive energy, and partly contributed by both induction and dispersion energies.     

Polysulfonylamine. CLXXXIV. Kristallstrukturen molekularer Triphenylphosphangold(I)‐di(4‐X‐benzolsulfonyl)‐amide: Isomorphie und dichte Packung (X = Me,F, Cl,NO2) vs. struktursteuernde Halogenbrücken C–X···Au/O (X = Br,I)

Polysulfonylamines. CLXXXIV. Crystal Structures of Molecular Triphenylphosphanegold(I) Di(4‐X‐benzenesulfonyl)amides: Isomorphism and Close Packing (X = Me, F, Cl, NO₂) vs. Structure‐Determining C–X···Au/O Halogen Bonds (X = Br, I) In order to study the structure‐determining influence that halogen bonding can exert during the course of crystallization, solid‐state structures are compared for two previously reported and four new molecular gold(I) complexes of the type Ph₃P–Au–N(SO₂–C₆H₄–4‐X)₂, each featuring linear P,N coordination at gold and two phenyl rings with varying p‐substituents X = Me, F, Cl, NO₂, Br or I. The compounds were synthesized by reactions of Ph₃PAuX (X = Cl or I) with the corresponding silver di(arenesulfonyl)amides, crystallized from dichloromethane, and characterized by low‐temperature X‐ray diffraction. The Me, F, Cl and NO₂ congeners are isomorphic and crystallize without solvent inclusion in the chiral orthorhombic space group P2₁2₁2₁ (Z′ = 1). These structures are governed by isotropic close packing via three‐dimensional 2₁ symmetry, incidentally supported by an invariant set of C–H···O=S hydrogen bonds, CH/π interactions and π/π stackings of aromatic rings; in particular, the hard halogen atoms of the fluoro and the chloro homologues are not involved in X···Au, X···O or X···X interactions. The higher homologues, with soft halogen atoms, were obtained as a dichloromethane hemisolvate for X = Br and a corresponding monosolvate for X = I, each triclinic in the centrosymmetric space group (Z′ = 1). Here, the primary structural effect is implemented by infinite chains in which translation‐related molecules are connected for the bromo compound by a bifurcated Au···Br(2)···O=S interaction, for the iodo congener by an equivalent Au···I(2)···O=S interaction and a short halogen bond C–I(1)···O=S. The latter bond is stronger than a similar C–Br···O=S interaction and induces a conformational adjustment of the (CSO₂)₂N group from the normal twofold symmetry in the bromo compound to an energetically unfavourable asymmetric form in the iodo homologue. In both cases, pairs of antiparallel molecular catemers are associated into strands via sixfold phenyl embraces, the strands are stacked to form layers, the solvent molecules are intercalated between adjacent layers, and the crystal packings are reinforced by a number of C–H···O=S hydrogen bonds and interactions of aromatic rings.     

An insight into C?H···N hydrogen bond and stability of the complexes formed by trihalomethanes with ammonia and its monohalogenated derivatives

A theoretical study of the C? H···N hydrogen bond in the interactions of trihalomethanes CHX₃ (X = F, Cl, Br) with ammonia and its halogen derivatives NH₂Y (Y = F, Cl, Br) has been carried out thoroughly. The complexes are quite stable, and their stability increases in going from CHF₃ to CHCl₃ then to CHBr₃ when Y keeps unchanged. With the same CHX₃ proton donor, enhancement of the gas phase basicity of NH₂Y strengthens stability of the CHX₃···NH₂Y complex. The C? H···N hydrogen bond strength is directly proportional to the increase of proton affinity (PA) at N site of NH₂Y and the decrease of deprotonation enthalpy (DPE) of C? H bond in CHX₃. The CHF₃ primarily appears to favor blue shift while the red‐shift is referred to the CHBr₃. The blue‐ or red‐shift of CHCl₃ strongly depends on PA at N site of NH₂Y. We suggest the ratio of DPE/PA as a factor to predict which type of hydrogen bond is observed upon complexation. The SAPT2+ results show that all C? H···N interactions in the complexes are electrostatically driven regardless of the type of hydrogen bond, between 48% and 61% of the total attractive energy, and partly contributed by both induction and dispersion energies.