The O–H···O, O–H···N and C–H···O hydrogen bonds in 1,4-dimethylpiperazine mono-betaine monohydrate

1,4-Dimethylpiperazine mono-betaine (1-carboxymethyl-1,4-dimethylpiperazinium inner salt, MBPZ) crystallizes as monohydrate. The crystals are orthorhombic, space group Pccn. Two MBPZ molecules and two water molecules form a cyclic oligomer, (MBPZ·H₂O)₂. The O–H···O and O–H···N hydrogen bonds are of 2.769(1) and 2.902(1) Å, respectively. The dimers interact with the neighboring molecules through the C–H···O hydrogen bonds of 3.234(1) Å. The piperazine ring assumes a chair conformation with the N(4)–CH₃ and N⁺(1)–CH₂COO⁻ groups in the equatorial position and the N⁺(1)–CH₃ group in the axial one. The FTIR spectrum is compared with that calculated by the B3LYP/6-31G(d,p) level of theory.     

复合物HNO···H2O2内N-H···O蓝移氢键的理论研究

A theoretical study on the blue-shifted H-bond N-H…O and red-shifted H-bond O-H…O in the complexHNO…H_2O_2 was conducted by employment of both standard and counterpoise-corrected methods to calculate thegeometric structures and vibrational frequencies at the MP2/6-31G(d),MP2/6-31 G(d,p),MP2/6-311 q G(d,p),B3LYP/6-31G(d),B3LYP/6-31 G(d,p) and B3LYP/6-311 G(d,p) levels.In the H-bond N-H…O,the calcu-lated blue shift of N-H stretching frequency is in the vicinity of 120 cm~(-1) and this is indeed the largest theoreticalestimate of a blue shift in the X-H…Y H-bond ever reported in the literature.From the natural bond orbital analy-sis,the red-shifted H-bond O-H…O can be explained on the basis of the dominant role of the hyperconjugation.For the blue-shifted H-bond N-H…O,the hyperconjugation was inhibited due to the existence of significant elec-tron density redistribution effect,and the large blue shift of the N-H stretching frequency was prominently due tothe rehybridization of sp~n N-H hybrid orbital.     

A Molecular Hexacoordinated Triorganoaluminum Compound with Trifold Si–H···Al Coordination

The synthesis of a hexacoordinate triorganoaluminum compound Al(NapSiH)₃ ( 6 ) (NapSiH = 8‐dimethylsilylnaphthyl) is reported. Three additional Si–H ··· Al contacts complete the coordination sphere around the central aluminum atom. Structural and spectroscopic evidence is provided for an activation of the Si–H bond by the aluminum Lewis acid. This activation is however small when compared to other recently described aluminum / silane complexes. These findings are supported by the results of quantum mechanical calculations, which indicate the presence of three Si–H ··· Al three center intractions in complex 6 .     

Computational Study on the Unconventional Hydrogen‐Bonded F–H···C Systems

The F–H···YZ₂ (Y = C, Si, BH, A1H;Z = H, PH₃) systems were examined using density functional theory calculations. The main focus of this work is to demonstrate that the chemistry of Y(PH₃)₂ exhibits a novel feature which is a central Y atom with unexpected high basicity. Further, the hydrogen bond strength can be adjusted by the substitution of H atoms of YH₂ by PH₃ groups. The FH···C(PH₃)₂ system has the strongest hydrogen bond interaction, which is larger than a conventional hydrogen bond. In addition to electrostatic interaction, donor‐acceptor interaction also plays an important role in determining the hydrogen bond strength. Therefore, a carbon atom can not only be the hydrogen bond acceptor but also can create an unusual stabilized hydrogen bond complex. Also, X₃B–YZ₂ (X = H, F; Y = C, Si, BH, A1H;Z = PH₃, NH₃) systems were examined, and it was found that the bond strength is controlled predominately by the HOMO‐LUMO gap (ΔIP). The smaller the ΔIP, the larger the bond dissociation energy of the B–Y bond. In addition, NH₃ is a better electron‐donating group than PH₃, and thus forms the strongest donor‐acceptor interaction between X₃B and Y(NH₃)₂.     

New chiral macrocyclic phosphoramidate self‐associated by an intermolecular N–H ··· O = P hydrogen bond

New macrocyclic chiral phosphoramidates containing 2,5‐diaryl‐1,3, 4‐oxadiazole and L‐alanine methyl ester units were synthesized by a convenient one‐pot procedure, X‐ray analysis of one chiral macrocycle shows that the phosphoramidate molecules are self‐associated by intermolecular N–H ··· O = P hydrogen bonds, the layer stacking along the b axis forming channels parallel to the b axis. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:480–484, 2001     

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).     

Influence of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH3 complexes

The effect of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH₃ (X = F, Cl, Br, OH, H, Me) and NCH···NH₃ complexes were investigated by quantum chemical calculations. Ab initio calculations were performed using MP2 method with a wide range of basis sets. With tacking into account the BSSE and ZPVE, the values of BEs decrease. Replacement of the nonparticipatory hydrogen atom of HCCH by the electronegative atoms (F, Cl, and Br), lead to the BEs increases. The BE corresponding to the replacement of the nonparticipatory hydrogen atom of HCCH by the OH and CH₃ groups decreases. A far greater enhancement of the interaction energy arises from replacement of HCCH by the more acidic HCN. The natural bond orbital analysis and the Bader's quantum theory of atoms in molecules were also used to elucidate the interaction characteristics of these complexes. The electrostatic nature of H‐bond interactions is predicted from QTAIM analysis. In addition, the relationship between the isotropic and anisotropic chemical shifts of the bridging hydrogen and binding energy of complexes as well as electron density at N···H BCPs were investigated. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Interaction of aromatic units of amino acids with guanidinium cation: The interplay of π···π, XH···π, and M+···π contacts

Complexes formed by guanidinium cation and a pair of aromatic molecules among benzene, phenol, or indole have been computationally studied to determine the characteristics of the cation···π interaction in ternary systems modeling amino acid side chains. Guanidinium coordinates to the aromatic units preferentially in the following order: indole, phenol, and benzene. Complexes containing two different aromatic units show an intermediate behavior between that observed for complexes with only one kind of aromatic unit. Most stable structures correspond to doubly‐T shaped arrangements with the two aromatic units coordinating guanidinium by its NH₂ groups. Other structures with only one aromatic unit coordinated to guanidinium, such as T‐shaped or parallel‐stacked ones, are less favorable but still showing significant stabilization. In indole and phenol complexes, the formation of hydrogen bonds between the aromatic molecules introduces extra stabilization in T‐shaped structures. Three body effects are small and repulsive in doubly T‐shaped minima. Only when hydrogen bonds involving the aromatic molecules are formed in T‐shaped structures a cooperative effect can be observed. In most complexes the interaction is controlled by electrostatics, with induction and dispersion also contributing significantly depending on the nature and orientation of the aromatic species forming the complex. Although the stability in these systems is mainly controlled by the intensity of the interaction between guanidinium and the aromatic molecules coordinated to it, interactions between aromatic molecules can modulate the characteristics of the complex, especially when hydrogen bonds are formed. © 2014 Wiley Periodicals, Inc.     

Supramolecular Networks Extended by N–H···O Interactions between Cu‐Benzimidazole Subunits and Keggin Anions

Three new 2D/3D supramolecular architectures derived from Cu‐organic subunits and Keggin anions, [Cu^II₂(biz)₈(HPMo^VI₁₀Mo^V₂O₄₀)(H₂O)₂] · 2H₂O ( 1 ), [Cu^I₄(biz)₈(SiW₁₂O₄₀)] · 2H₂O ( 2 ) and [Cu^I₂(dmbiz)₄(Hdmbiz)₂(SiW₁₂O₄₀)] ( 3 ) (biz = benzimidazole, dmbiz = 5, 6‐dimethyl benzimidazole), were obtained under hydrothermal conditions. Single crystal X‐ray diffraction analysis reveals that compound 1 has two kinds of [Cu^II(biz)₂]²⁺ cations, which are further extended by Keggin anions into a 2D (4, 8)‐connected supramolecular network by hydrogen bonding interactions. In compound 2 , four types of [Cu^I(biz)₂]⁺ subunits link the [SiW₁₂O₄₀]^4– anions to form a 3D (2, 6)‐connected supramolecular structure. Compound 3 shows a 3D supramolecular network with a NaCl‐type topology constructed by [Cu^I(dmbiz)₂]⁺ subunits, anions, and discrete [Hdmbiz]⁺ cations. Moreover, the electrochemical and photocatalytic properties of compounds 1 and 2 were investigated.     

Phencyclone Diels-Alder adducts as a new crystalline host. Role of C---H···π and C---H···O interactions

A series of crystalline host compounds, which have a bicyclo[2.2.1]heptene-7-one system, has been synthesized and their inclusion behavior has been investigated. The cycloadduct of phencyclone and N-naphthylmaleimide forms a 1:1 crystalline inclusion complex with 2-butanone. The crystal structure indicates the presence of weak lattice forces supported by C---H···π and C---H···O interactions.     

Van Der Waals heterogeneous layer‐layer carbon nanostructures involving π···H‐C‐C‐H···π···H‐C‐C‐H stacking based on graphene and graphane sheets

Noncovalent interactions involving aromatic rings, such as π···π stacking, CH···π are very essential for supramolecular carbon nanostructures. Graphite is a typical homogenous carbon matter based on π···π stacking of graphene sheets. Even in systems not involving aromatic groups, the stability of diamondoid dimer and layer‐layer graphane dimer originates from C − H···H − C noncovalent interaction. In this article, the structures and properties of novel heterogeneous layer‐layer carbon‐nanostructures involving π···H‐C‐C‐H···π···H‐C‐C‐H stacking based on [n ]‐graphane and [n ]‐graphene and their derivatives are theoretically investigated for n = 16–54 using dispersion corrected density functional theory B3LYP‐D3 method. Energy decomposition analysis shows that dispersion interaction is the most important for the stabilization of both double‐ and multi‐layer‐layer [n ]‐graphane@graphene. Binding energy between graphane and graphene sheets shows that there is a distinct additive nature of CH···π interaction. For comparison and simplicity, the concept of H‐H bond energy equivalent number of carbon atoms (noted as NHEQ), is used to describe the strength of these noncovalent interactions. The NHEQ of the graphene dimers, graphane dimers, and double‐layered graphane@graphene are 103, 143, and 110, indicating that the strength of C‐H···π interaction is close to that of π···π and much stronger than that of C‐H···H‐C in large size systems. Additionally, frontier molecular orbital, electron density difference and visualized noncovalent interaction regions are discussed for deeply understanding the nature of the C‐H···π stacking interaction in construction of heterogeneous layer‐layer graphane@graphene structures. We hope that the present study would be helpful for creations of new functional supramolecular materials based on graphane and graphene carbon nano‐structures. © 2017 Wiley Periodicals, Inc.     

Unconventional H‐bonds: SH···N interaction

Quantum calculations at the MP2/aug‐cc‐pVDZ level are used to analyze the SH···N H‐bond in complexes pairing H₂S and SH radical with NH₃, N(CH₃)₃, NH₂NH₂, and NH₂N(CH₃)₂. Complexes form nearly linear H‐bonds in which the S? H covalent bond elongates and shifts its stretching frequency to the red. Binding energies vary from 14 kJ/mol for acceptor NH₃ to a maximum of 22 kJ/mol for N(CH₃)₃ and N(CH₃)₂NH₂. Analysis of geometric, vibrational, and electronic data indicate that the SH···N interaction involving SH is slightly stronger than that in which the closed‐shell H₂S serves as donor. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Zur Chemie in Schmelzlösungen. V. Darstellung kristalliner Halogenowolframate und Halogenomolybdate MeO · MeWO4 · nMeX2 bzw · MeO · MeMoO4 · nMeX2

Preparation and crystal growth of halogenotungstates and halogenomolybdates from molten salt solutions are described. Characteristic properties of this new class of compounds are communicated.     

A polarizable dipole–dipole interaction model for evaluation of the interaction energies for NH···OC and CH···OC hydrogen‐bonded complexes

In this article, a polarizable dipole–dipole interaction model is established to estimate the equilibrium hydrogen bond distances and the interaction energies for hydrogen‐bonded complexes containing peptide amides and nucleic acid bases. We regard the chemical bonds N? H, C?O, and C? H as bond dipoles. The magnitude of the bond dipole moment varies according to its environment. We apply this polarizable dipole–dipole interaction model to a series of hydrogen‐bonded complexes containing the N? H···O?C and C? H···O?C hydrogen bonds, such as simple amide‐amide dimers, base‐base dimers, peptide‐base dimers, and β‐sheet models. We find that a simple two‐term function, only containing the permanent dipole–dipole interactions and the van der Waals interactions, can produce the equilibrium hydrogen bond distances compared favorably with those produced by the MP2/6‐31G(d) method, whereas the high‐quality counterpoise‐corrected (CP‐corrected) MP2/aug‐cc‐pVTZ interaction energies for the hydrogen‐bonded complexes can be well‐reproduced by a four‐term function which involves the permanent dipole–dipole interactions, the van der Waals interactions, the polarization contributions, and a corrected term. Based on the calculation results obtained from this polarizable dipole–dipole interaction model, the natures of the hydrogen bonding interactions in these hydrogen‐bonded complexes are further discussed. © 2013 Wiley Periodicals, Inc.     

Synthesis,Spectroscopy and Crystal Structures of Chiral Organic Ammonium Tetrathiometalates Showing N‐H···S and C‐H···S Interactions

The reaction of ammonium tetrathiometalate (NH₄)₂[MS₄] (M = W or Mo) with the R(+) or S(?) forms of the organic amine α‐methylbenzylamine [PhCH(CH₃)NH₂] results in the formation of the corresponding non‐centrosymmetric bis(α‐methylbenzylammonium) tetrathiometalate complexes [PhCH(CH₃)NH₃]₂[MS₄] (R‐ammonium M = W 1 ; R‐ammonium M = Mo 2 ; S‐ammonium M = W 3 , S‐ammonium M = Mo 4 ) which were characterized by elemental analysis, IR, Raman, UV‐Vis and CD spectra, X‐ray powder diffractometry and single crystal X‐ray crystallography. Compounds 1 ‐ 4 crystallize in the chiral space group P2₁ and constitute the first examples of structurally characterized chiral organic ammonium group VI tetrathiometalates. The structures of 1 ‐ 4 consist of two crystallographically independent chiral organic ammonium cations and a tetrahedral tetrathiometalate dianion. The N‐H···S and C‐H···S interactions between the anions and cations organise them such that the organic ammonium ions always point towards the S atoms of [MS₄]^2?.     

Synthese und Kristallstruktur von [WNCl3 · NC–Ph]4 · 3 CH2Cl2

Synthesis and Crystal Structure of [WNCl₃ · NCPh]₄ · 3 CH₂Cl₂ The adduct of tungsten nitride trichloride with benzonitrile, [WNCl₃ · NCPh]₄, is formed by the reaction of N,N,N'-tris(trimethylsilyl)benzamidine and tungsten hexachloride in CCl₄ solution. It forms red crystal needles and was characterized by its IR spectrum and an X-ray crystal structure determination (1983 unique observed reflexions, R = 0.075). Crystal data: a = 1464.8, b = 1902.6, c = 2033.8 pm, β = 102.27°, space group C2/c, Z = 4. In the [WNCl₃ · NCPh]₄ molecule the tungsten atoms were located at the vertices of a square and are linked with one another via linear W?N? W nitrido bridges with alternating short and long bonds having average lengths of 166 and 211 pm. The N atoms of the benzonitrile ligands are in the positions trans to the W?N bonds at distances of 237 pm.