Hydrogen Bonding Properties of the Complexes of Formaldehyde and its Derivatives with HF and HCl

Summary.  The complexes of formaldehyde and some of its derivatives with HF and HCl were investigated at HF/6-311 + +G^** and MP2/6-311 + +G^** levels of theory. Interaction energies were corrected for the basis set superposition error (BSSE). The full optimizations of dimers and monomers were performed during calculations. The Bader theory of atoms-in-molecules (AIM) was also applied for the localization of bond critical points (BCP) and for the calculation the electron densities and their Laplacians at these points. The relationships between H-bond energy and parameters obtained from calculations were also studied. Received June 29, 2001. Accepted (revised) October 29, 2001     

Theoretical Study on the Structures and Properties of Hydrogen Bonding Complexes between Diazines and Water

Density functional theory B3LYP method and second-order Moller-Plesset perturbation theory MP2 method were employed to obtain the optimized geometries of the ground state and interaction energy for diazines and water complexes. The results show that the ground state complexes have strong hydrogen bonding interaction with -20.99, -16.73 and -15.31 kJ/mol after basis set superposition error and zero-point vibration energy correction for pyridazine-water, pyrimidine-water and pyrazine-water, respectively, and large red-shift for the symmetric H-O stretching vibration frequencies due to the formation of N…H-O hydrogen bond in the diazine-water complexes. The NBO analysis indicates that intermolecular charge transfer are 0.0316, 0.0255 and 0.0265 e respectively. In addition, the first singlet （n,n＊） vertical excitation energy of the monomer and the hydrogen bonding complexes between diazines and water was investigated by time-dependent density functional theory.     

吡咯与HCl和CHCl3分子间Cl(C)-H…π型氢键的理论研究

运用量子化学从头算(ab initio)方法,采用6-31G(d,p)基组对吡咯和HCl单体进行优化,结果表明MP2／6-31G(d,p)计算结果与实验结果较吻合．然后采用MP2／6-31G(d,p)方法对吡咯-HCl体系以及吡咯-CHCl3体系的分子间Cl(C)-H…π型氢键进行了理论研究,并在MP2／aug-cc-pVDZ水平计算了氢键作用能．研究表明,吡咯与HCl分子和CHCl3之间形成了Cl(C)-H…π型氢键,吡咯与HCl分子的氢键相互作用使HCl中H-Cl键长增加,振动频率减小了149cm^-1(红移);而吡咯与CHCl3之间的相互作用使CHCl3中的C-H键长减小,振动频率增加了33cm^-1(蓝移)．利用自然键轨道(NBO)分析表明电荷发生转移,吡咯-HCl体系中HCl得到0．0155e;吡咯-CHCl3体系中CHCl3得到0．0098e．     

Hydrogen Bonding versus Halogen Bonding: Spectroscopic Investigation of Gas-Phase Complexes Involving Bromide and Chloromethanes

Hydrogen bonding and halogen bonding are important non-covalent interactions that are known to occur in large molecular systems, such as in proteins and crystal structures. Although these interactions are important on a large scale, studying hydrogen and halogen bonding in small, gas-phase chemical species allows for the binding strengths to be determined and compared at a fundamental level. In this study, anion photoelectron spectra are presented for the gas-phase complexes involving bromide and the four chloromethanes, CH₃Cl, CH₂Cl₂, CHCl₃, and CCl₄. The stabilisation energy and electron binding energy associated with each complex are determined experimentally, and the spectra are rationalised by high-level CCSD(T) calculations to determine the non-covalent interactions binding the complexes. These calculations involve nucleophilic bromide and electrophilic bromine interactions with chloromethanes, where the binding motifs, dissociation energies and vertical detachment energies are compared in terms of hydrogen bonding and halogen bonding.     

Hydrogen and Halogen Bonding to Au(I) Fluorido Complexes

The hydrogen bonding in the Au(I) complex [Au(F ⋅ HF)(SPhos)] (SPhos=dicyclohexyl(2’,6’-dimethoxy[1,1’-biphenyl]-2-yl)phosphane) ( 1 a ⋅ HF) has been analysed by IR and NMR measurements, revealing the formation of an unsymmetrical bifluoride moiety. The data are in excellent agreement with DFT calculations. Comparisons to analogous complexes bearing NHC (NHC=N-heterocyclic carbene) ligands demonstrated a comparable bonding situation. The identity of the halogen bond in the compound [Au(F ⋅ IC₆F₅)(SPhos)] ( 1 a ⋅ IC₆F₅) in CD₂Cl₂ has been estimated, and van't Hoff data for the equilibrium between [Au(F)(SPhos)] ( 1 a ) and IC₆F₅ with [Au(F ⋅ IC₆F₅)(SPhos)] are ΔH⁰=−8.1(3) kJ mol⁻¹ and ΔS⁰=−36(1) J (mol K)⁻¹. The latter are also in agreement with DFT calculations. For all calculations, comparisons between an explicit and implicit solvent model were drawn. Single crystal X-ray diffraction studies were performed for [Au(F ⋅ 2IC₆F₅)(BrettPhos)] ⋅ 2IC₆F₅ (BrettPhos=2-(dicyclohexylphosphino)-3,6-dimethoxy-2’,4’,6’-triisopropyl-1,1’-biphenyl) ( 1 b ⋅ 4IC₆F₅) demonstrating the presence of halogen bonds to Au(I) fluorido complexes in the solid state.     

Supramolecular Formation via Hydrogen Bonding in Copper and Nickel Complexes with 2-Hydroxynicotinic Acid

Two complexes,Cu(HnicO)2 1 and Ni(HnicO)2(H2O)2 2 (H2nicO=2-hydroxy-nicolinic acid),were synthesized by hydrothermal reactions and structurally characterized. Complex 1 crystallizes in monoclinic,space group P21/n,with a=8.314(7),b=6.275(4),c=11.283(7),β =98.32(3)°,V=582.5(7)3,Z=2,Mr=339.74,Dc=1.937 g/cm3,F(000)=342,μ=1.908 mm-1,S =1.097,the final R=0.0284 and wR=0.0781 for 1177 observed reflections with I > 2σ(I). Complex 2 crystallizes in monoclinic,space group P21/c,with a=7.438(5),b=12.22(1),c=7.537(5),β=100.07(3)°,V=674.3(8)3,Z=2,Mr=370.95,Dc=1.827 g/cm3,F(000)=380,μ =1.487 mm-1,S=1.041,the final R=0.0335 and wR=0.0779 for 1202 observed reflections with I > 2σ(I). There are extended 3D framework structures in complexes 1 and 2 due to the N–H…O and C–H…O hydrogen bonds. The copper atom in 1 has square planar coordination,while the nickel atom in 2 adopts octahedral coordination geometry. The TG curve shows that complex 2 is stable in solid state to 150 ℃.     

Hydrogen Bonded Complexes of Acetylacetone and Methanol: HF and DFT level Study

Summary. Several possible hydrogen-bonded complexes between the tautomeric forms of acetylacetone and methanol were studied by ab initio methods using 6-311G** and D95** basis functions at the HF and DFT (B3LYP) levels of theory. The calculations were carried out for isolated molecules and solvent assisted complexes by means of the isodensity polarized model (IPCM). The theoretical frequencies were compared with the experimental IR spectrum of an equimolar mixture of acetylacetone and methanol. It was proved that the most stable H-bonded complex acetylacetone–methanol is formed between O-bonded methanol- and the enol molecule.     

Hydrogen Bonded Complexes of Acetylacetone and Methanol: HF and DFT level Study

Several possible hydrogen-bonded complexes between the tautomeric forms of acetylacetone and methanol were studied by ab initio methods using 6-311G** and D95** basis functions at the HF and DFT (B3LYP) levels of theory. The calculations were carried out for isolated molecules and solvent assisted complexes by means of the isodensity polarized model (IPCM). The theoretical frequencies were compared with the experimental IR spectrum of an equimolar mixture of acetylacetone and methanol. It was proved that the most stable H-bonded complex acetylacetone–methanol is formed between O-bonded methanol- and the enol molecule.     

Hydrogen Bonding in Phosphine Oxide/Phosphate–Phenol Complexes

To develop a new solvent‐impregnated resin (SIR) system for the removal of phenols and thiophenols from water, complex formation by hydrogen bonding of phosphine oxides and phosphates is studied using isothermal titration calorimetry (ITC) and quantum chemical modeling. Six different computational methods are used: B3LYP, M06‐2X, MP2, spin component‐scaled (SCS) MP2 [all four with 6‐311+G(d,p) basis set], a complete basis set extrapolation at the MP2 level (MP2/CBS), and the composite CBS‐Q model. This reveals a range of binding enthalpies (ΔH) for phenol–phosphine oxide and phenol–phosphate complexes and their thio analogues. Both structural (bond lengths/angles) and electronic elements (charges, bond orders) are studied. Furthermore, solvent effects are investigated theoretically by the PCM solvent model and experimentally via ITC. From our calculations, a trialkylphosphine oxide is found to be the most promising extractant for phenol in SIRs, yielding ΔH=?14.5 and ?9.8 kcal mol^?1 with phenol and thiophenol, respectively (MP2/CBS), without dimer formation that would hamper the phenol complexation. In ITC measurements, the ΔH of this complex was most negative in the noncoordinating solvent cyclohexane, and slightly less so in π–π interacting solvents such as benzene. The strongest binding is found for the dimethyl phosphate–phenol complex [?15.1 kcal mol^?1 (MP2/CBS)], due to the formation of two H‐bonds (P?O???H‐O‐ and P‐O‐H???O‐H); however, dimer formation of these phosphates competes with complexation of phenol, and would thus hamper their use in industrial extractions. CBS‐Q calculations display erroneous trends for sulfur compounds, and are found to be unsuitable. Computationally relatively cheap SCS‐MP2 and M06‐2X calculations did accurately agree with the much more elaborate MP2/CBS method, with an average deviation of less than 1 kcal mol^?1.     

四苯氧基酞菁钴及其吡啶衍生物的配合物的合成和性质

合成了2,2′,2″,2-四苯氧基酞菁钴配合物[TPhOPeCo(Ⅱ)]及其与吡啶衍生物的配合物[TPhOPcCo(Ⅱ)(L)_2](L=Py,MePy,AnPy),测定了其IR、UV-Vis、热稳定性及其在DMF中的氧化还原半波电位、电子转移速度常数和在不同电位电解下的电子吸收光谱。     

Substituent Effects on the Hydrogen Bonding Between Phenolate and HF, H2O and NH3

IntroductionSubstituent effects have been well known forthe covalently bonded systems for many years,they have found tremendous applications in medicalchemistry,biochemistry,organic chemistry,andmaterial chemistry[1] . In fact,the studies ofsubstituent effects have greatly contributed to ourunderstanding of chemical mechanisms,and theestablishments of many chemical theories haveheavily relied on the observed substituent effects.However,it turns out that little have beenknown so far the substit…     

Electrical and Spectral Properties of Manganese Dichloride Complexes with N-Oxides of Pyridine Derivatives

Polycrystalline complexes of MnCl₂ with N-oxides of pyridine, 2-picoline, and 2,6-lutidine contain a molecule of strongly retained crystallization water; two types of the labile networks of hydrogen bonds are formed on the crystal surface. Under solar radiation the long-lived F-centers are formed in the crystals, imparting a specific color to the compounds. The thermal motion of MnCl₂ complexes with lutidine N-oxide in the unit cells can be described as gas-like motion. At low temperatures the electrical conductivity is predominantly maintained by protons, whereas at high temperatures another mechanism of conductivity arises.     

吡啶与HCl和CHCl3形成分子间红移氢键和蓝移氢键的理论研究

采用量子化学从头算的MP2方法, 分别在6-31G(d,p), 6-311+G(d,p)和AUG-cc-pVDZ基组下, 研究了复合物C5H5N…HCl(1), C5H5N…HCCl3(2)和C5H5N…HCCl3(3)的分子间氢键. 计算结果表明, 在复合物1中, HCl中Cl—H键伸长, 形成Cl—H…N红移氢键; 在复合物2中, HCCl3中C—H键伸长, 形成C—H…N 红移氢键; 在复合物3中, HCCl3中C—H键收缩, 形成C—H…π蓝移氢键. 自然键轨道(NBO)分析表明, 影响氢键红移和氢键蓝移主要有3个因素: n(Y)→σ*(X—H)超共轭作用、X—H键轨道再杂化和质子供体电子密度重排. 其中, 超共轭作用属于键伸长效应, 电子密度重排和轨道再杂化属于键收缩效应. 在复合物1和2中, 由于键伸长效应处于优势地位导致形成红移氢键; 在复合物3中, 由于键收缩效应处于优势地位导致形成蓝移氢键.     

Electrical and Spectral Properties of Complexes of Pyridine N-Oxide Derivatives with Iron Trichloride

Complexes (1 : 2) of iron trichloride with N-oxides of pyridine, picolines, and 2,6-lutidine were studied by optical spectroscopy, dielectrometry, and conductometry. In solid complexes, three crystalline phases are in equilibrium; the nuclei of each of these phases can be detected in the oily state. The enthalpies of the coordination bonds are different in different phases. One of the phases of the 3-picoline N-oxide complex shows a strong orientation disorder; disappearance of the short-range order causes weakening of the coordination bonds by 1.6 kcal. The thermal motion of free base molecules in two phases of the 2,6-lutidine N-oxide complex is gaslike. In the solid phase of this complex, there is a strong distribution of the relaxation frequencies; the mean relaxation frequency is close to 220 Hz. Upon irradiation of the complexes with solar or UV light, specific coloration centers can form. Weak alternating electric fields initiate in some compounds reversible chemical reactions. The intermolecular and charge equilibria in the compounds are very labile; the energy of generation of the low-temperature electrical conductivity in them is close to 0.9 eV.     

Theoretical Study on the Hydrogen Bonding Interactions in Complexes of 5‐Hydroxytryptamine with Water

The energies, geometries and harmonic vibrational frequencies of 1:1 5‐hydroxytryptamine‐water (5‐HT‐H₂O) complexes are studied at the MP2/6‐311++G(d,p) level. Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM) analyses and the localized molecular orbital energy decomposition analysis (LMO‐EDA) were performed to explore the nature of the hydrogen‐bonding interactions in these complexes. Various types of hydrogen bonds (H‐bonds) are formed in these 5‐HT‐H₂O complexes. The intermolecular C4H5^5‐HT···O^w H‐bond in HTW3 is strengthened due to the cooperativity, whereas no such cooperativity is found in the other 5‐HT‐H₂O complexes. H‐bond in which nitrogen atom of amino in 5‐HT acted as proton donors was stronger than other H‐bonds. Our researches show that the hydrogen bonding interaction plays a vital role on the relative stabilities of 5‐HT‐H₂O complexes.     

Model potential calculations for HF and HCl

A model potential method proposed recently by the present authors has been tested successfully for HF and HCl. Calculated values of total energies, orbital energies and spectroscopic constants are quite acceptable.     

Physicochemical Properties of Water Clusters in the Presence of HCl and HF Molecules. Molecular Dynamic Simulation

The molecular dynamic method is used to study the physicochemical properties of water clusters containing HCl and HF molecules. These impurity molecules have the ability to undergo hydration in water vapor. In clusters with the same number of water molecules, large dipole moments are induced for HCl, and smaller ones, for HF. The diffusion coefficient of the impurity in the clusters is slightly lower than the analogous characteristic for water molecules and exhibits nonmonotonous behavior with increasing size of the aggregate.     

Detection of HCl and HF by TTFMS and WMS

In this work we discuss on a compact spectrometer based on DFB diode lasers for detection of chloridric and fluoridric acids. HCl and HF concentrations are determined through optical absorption of the P(4) line (lambda=1.7 microm) and the R(3) line (lambda=1.3 microm), respectively. Both lines belong to first overtone vibrational bands and their line strengths are 7.8 x 10(-21)cm/molecule for HCl and 2.8 x 10(-20)cm/molecule for HF. We chose these lines for their relative high intensities and because they are quite far from water vapour lines which represent the main interfering gas for trace-gases analysis. To detect these species we used two different high frequency modulation techniques: two-tone frequency modulation spectroscopy (f(1)=800 MHz and f(2)=804 MHz) was used for HCl while for HF we followed a simpler approach based on wavelength modulation spectroscopy (f=600 kHz). We demonstrate that the two techniques provide comparable detection limit of about 80 ppbV at atmospheric pressure. Positive testing of our spectrometer makes it suitable for in situ measurements of exhaust gases coming from waste incinerators.     

1,10-菲咯啉及其衍生物铜配合物的抗癌活性研究进展

作为一种微量生命元素,铜在生物进程中扮演着重要角色,很多铜配合物呈现抑制癌细胞增殖的活性。本文论述了以1,10-菲咯啉及其衍生物为配体的铜配合物的抗癌活性研究进展,分析了其对DNA裂解的可能机理。对比顺铂类抗癌药物,展望了铜配合物作为抗癌药物的应用前景。     

Comparative Analysis of Hydrogen,van der Waals,and Halogen Bonds in Ammonia Complexes with HCl and ClF Molecules

Russian Journal of Physical Chemistry A - Quantum chemical calculations of molecular complexes formed by ammonia and methanide (electron pair donor) with HCl and ClF molecules (acceptor) at...