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1.
Hassan S. Bazzi Siham Y. AlQaradawi Adel Mostafa El-Metwally Nour 《Journal of Molecular Structure》2008,879(1-3):60-71
The interactions of the electron donors piperazine (PIP) and N,N′-dimethylpiperazine (DMPIP) with the σ-acceptor iodine and the π-acceptors tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) were studied spectrophotometrically in chloroform at 25 °C. The electronic and infrared spectra of the resulting charge-transfer complexes were recorded, in addition to thermal analysis. The results obtained showed that the stoichiometries of the reactions are not fixed and depend on the nature of both the donor and the acceptor. The formed CT-complexes have the formulas of , [(PIP)(TCNE)2], [(PIP)(DDQ)2], , [(DMPIP)(TCNE)2] and [(DMPIP)(DDQ)2]. A general mechanism explaining the formation of triiodide complexes was suggested. 相似文献
2.
A new Zn(II) complex, [Zn(pyz)(H2O)4]pht (1) (pyz=pyrazine; pht=1,2-benzenedicarboxylate) has been hydrothermally synthesized and characterized. Complex 1 features a novel polar 3D framework with a 1D polycationic chain , between which pht2− dianions are encapsulated via the supramolecular interaction. Its powder SHG is of about three times as large as that of KH2PO4. 相似文献
3.
Franois Fillaux Alain Cousson Matthias J. Gutmann 《Journal of Molecular Structure》2006,790(1-3):122-128
Macroscopic quantum entanglement reveals an unforeseen mechanism for proton transfer across hydrogen bonds in the solid state. We utilize neutron scattering techniques to study proton dynamics in the crystal of potassiumhydrogencarbonate (KHCO3) composed of small planar centrosymmetric dimer entities linked by moderately strong hydrogen bonds. All protons are indistinguishable, they behave as fermions, and they are degenerate. The sublattice of protons is a superposition of macroscopic single-particle states. At elevated temperature, protons are progressively transferred to secondary sites at ≈0.6 Å from the main position, via tunnelling along hydrogen bonds. The macroscopic quantum entanglement, still observed at 300 K, reveals that proton transfer is a coherent process throughout the crystal arising from a superposition of macroscopic tunnelling states. 相似文献
4.
Jie-Hui Yu Qin Hou Ming-Hui Bi Zheng-Liang Lü Xiao Zhang Xue-Jian Qu Jing Lu Ji-Qing Xu 《Journal of Molecular Structure》2006,800(1-3):69-73
Four oxalate-bridged transition-metal supramolecular compounds [Co2(im)4(ox)2] 1, [Co(im)2(ox)] 2, [Mn(2,2′-bpy)(ox)] 3 and [Fe(H2O)2(ox)] 4 (im, imidazole; ox, oxalate; bpy, bipyridine) were obtained from the simple hydrothermal reactions of Mn+oxL (M, transition metal; L, aromatic N-donor ligand) system. They all exhibit the 1-D chain structures, consisting of the (or ML2+) units linked by oxalate bridges. Interestingly, the 1-D oxalate chains in the title compounds are further self-assembled into the 3-D supramolecular networks through the interchain various secondary bonding interactions. Because the units adopt the different configuration, the oxalate chains show either zigzag type as in compounds 1–3 or linear type as in compound 4. Compounds 1 and 2 are isomeric, and only in packing modes of interchain im molecules there exists the difference. 相似文献
5.
Fa-Nian Shi Filipe A. Almeida Paz Penka I. Girginova Luís Mafra Vítor S. Amaral Joo Rocha Anna Makal Krzysztof Wozniak Jacek Klinowski Tito Trindade 《Journal of Molecular Structure》2005,754(1-3):51-60
Two new compounds containing multidentate chelating organic residues of N-(phophonomethyl)iminodiacetic acid (H4pmida), [M(pyr)(H2O)4][M2(Hpmida)2(pyr)(H2O)2]·2(H2O) (where pyr=pyrazine and M=Co2+ or Ni2+ for I and II, respectively) have been synthesised and structurally characterised by single-crystal and powder X-ray diffraction, elemental analysis, infrared spectroscopy, thermal analysis and solid-state 31P MAS NMR. The compounds contain discrete binuclear anionic [M2(Hpmida)2(pyr)(H2O)2]2− units in which one pyrazine ligand bridges two M2+ cations which are completely trapped inside three five-membered chelate rings formed by the Hpmida3− ligands. These moieties close pack in the ac plane via a series of strong and highly directional O–HO hydrogen bonds leading to the formation of anionic layers. One-dimensional cationic coordination polymers are placed in-between and strongly hydrogen-bonded to these layers. The magnetic properties of these two materials are also reported. 相似文献
6.
Yan-Hong Cui Wei Quan Tian Ji-Kang Feng Zi-Zhong Liu Wei-Qi Li 《Journal of Molecular Structure》2007,810(1-3):65-72
Some η5-cyclopentadienyl cobalt dithiolene complexes CpCoS2C2R2 have been optimized at B3LYP/6-311++G(d) level. The optimized geometries agree well with experiment. The analyses of nature bond orbital and nucleus-independent chemical shift (NICS) at B3LYP/6-311++G(d) and GIAO-B3LYP/6-311++G(d) levels reveal the aromatic character of the η5-cyclopentadienyl cobalt dithiolene complexes. However, their aromaticity is weaker than that of the isolated . There are two reasons for the change of heterocyclic aromaticity of the metal dithiolene in the η5-cyclopentadienyl cobalt dithiolene complexes with respect to that of the isolated . The better equalization of bond lengths in the isolated cation is the first reason. The other reason is that the contribution to the NICS from the metallic cobalt atom is much larger in the isolated cation . The planar character of cyclopentadienyl is destroyed slightly in the complexes. At the same time, the size of cyclopentadienyl (Cp) becomes bigger than the isolated Cp−1 and this is caused by the cobalt atom in the pentagon. The π-electron delocalization causes stronger aromaticity of the Cp in the complexes than that of the isolated Cp−1. 相似文献
7.
Ying-Hua Sun Ji-Qing Xu Ling Ye Xiao-Bing Cui Yong Li Hai-Hui Yu Guang-Hua Li Guang-Di Yang Yan Chen 《Journal of Molecular Structure》2005,740(1-3):193-201
Two new interesting polyoxometalate derivatives 1 and 2 constructed of modified metal–oxo cluster ions carrying positive and negative changes, respectively, was hydrothermally prepared and structurally characterized by IR, ESR, XPS, elemental analysis and X-ray crystallography. The result of structure determination shows that compound 1 and 2 are isostructural and both contain polyoxocation and polyoxoanion, and both cation and anion are built on mixed Mo–V tetra-capped pseudo-Keggin units with P centre, [Mo8V8O40(PO4)]n−, bonded to four or two [Ni(2,2′-bipy)2H2O]2+ complexes, respectively, via terminal oxygen of the capping V atoms. Magnetism measurement indicates that there exists antiferromagnetic interaction in complex 1 and 2. 相似文献
8.
A new organically templated metal sulfate has been synthesized and characterized. At room temperature, dabcodiium hexaaquacopper(II) bis(sulfate), (C6H14N2)[Cu(H2O)6](SO4)2 crystallizes in the monoclinic symmetry (space group P21/n) with the following unit cell parameters: a = 6.9533(2), b = 12.5568(2), c = 9.9434(2) Å; β = 90.526(1)° and Z = 2. Its crystal structure is built from isolated [Cu(H2O)6]2+, and disordered ions linked together by a hydrogen-bonding network. The title compound undergoes a reversible phase transition of the first-order type at 265.7/281.8 K on heating–cooling runs. Below the phase transition temperature, the structure is fully ordered. 相似文献
9.
The molecular structures of the ground state and the first singlet excited state for , C6H5OH, C6H5O−, , C10H7OH and C10H7O−, the forms of phenol and 1-naphthol in acid and alkali solutions, were optimized by ab initio HF and configuration interaction with singlet excitations (CIS) method, respectively. Their fluorescent spectra were obtained by the time-dependent density functional theory (TD-DFT) using the B3LYP method with the 6-31+G (d) basis set. The frontier molecular orbital characteristics, fluorescent spectrum and proton affinities had been analyzed systematically in order to study different fluorescence of phenol and 1-naphthol in acid and alkali solutions. It was found that C6H5OH and are the main forms of phenol in acid solution, but C6H5O− in alkali solution; C10H7OH and C10H7O− are the main forms of 1-naphthol in alkali solution, but in acid solution. The calculated results are in good agreement with the experimental data. 相似文献
10.
B. Gervais M. Beuve G.H. Olivera M.E. Galassi R.D. Rivarola 《Chemical physics letters》2005,410(4-6):330-334
We present a simulation of liquid water radiolysis by swift carbon ions that explicitly takes into account multiple ionization of water molecules. For high linear energy transfer (LET), this process is not negligible with respect to single ionization. The rearrangement of highly ionized water molecules is consistent with production of atomic oxygen. Multiple ionizations is shown to be responsible for creation of a large amount of radicals and O2 molecules. The simulated yield reproduces very well direct optical measurements for swift ions with comparable LET. Our simulation for is in also agreement with experiment. 相似文献
11.
F. Pelascini Manuel Wesolek F. Peruch A. De Cian N. Kyritsakas P.J. Lutz J. Kress 《Polyhedron》2004,23(18):3193-3199
Dicationic iron complexes were obtained upon complexation of the ligands 6,6″-di(p-tolyl)-2,2′:6′,2″-terpyridine (L1) or 2,6-bis-(3-mesitylpyrazol-1-yl)pyridine (L2) with iron dichloride or iron trichloride. They were characterized by X-ray diffraction and FT-IR spectroscopy. Single crystal structure determinations of , and all show six-coordinate metal center. These complexes were obtained from L1FeCl2 and L2FeCl2 during recrystallization attempts. (L1)2Fe2+ was shown to be a high-spin complex, whereas (L2)2Fe2+ was shown to be low-spin. For , two independent dications of very similar geometry but with distinctive distortion were observed by X-ray analysis. 相似文献
12.
New regularities and an equation of state for liquids 总被引:1,自引:0,他引:1
Three regularities have been introduced for liquids (T < TC and ρ > ρC) based on average potential energy. The experimental data have been used to show the validity of the regularities. First, there exists near-linearity relation between and ρ for all isotherms of a liquid, where Pi and ρ are internal pressure and density, respectively. Second, changes linearly with ρ for each isotherm of any liquid, where Z and Vm are compressibility factor and molar volume, respectively. Third, a new regularity using the definition of bulk modulus and our new equation of state between reduced bulk modulus and density has been introduced, that is versus ρ must be linear for all isotherms of a liquid where Br is the reduced bulk modulus.
A new equation of state has been also derived. The density of some liquids in the extensive ranges of temperature and pressure has been calculated using the new equation of state. The densities calculated from this equation agree with experiment to better than 0.3%. The new equation of state can predict internal pressure, thermal expansion coefficient, and isothermal compressibility of liquids within experimental error. 相似文献
13.
Using a technique of laser flash photolysis coupled with vacuum ultraviolet laser-induced fluorescence spectroscopy, the rate coefficients of O(1D) reactions with N2, O2, N2O, and H2O at 295 ± 2 K have been determined to be , kO2=(4.06±0.24)×10-11, kN2O=(1.35±0.08)×10-10 and . The quoted uncertainties include estimated errors and are the 95% confidence level. The kN2 and kN2O values obtained are larger than the current NASA/JPL recommendations by 26% and 16%, respectively, although they are still within the error limits associated with the recommendations. 相似文献
14.
Kaiyu Liu Jinfeng Xu Shijun Liu Qiyuan Chen Zhongliang Xiao Daowu Yang 《Thermochimica Acta》2008,471(1-2):100-102
The excess molar enthalpies () for the binary mixtures of trimethyl phosphate (TMP) with alkanols {CH3(CH2)nOH, n = 0–3} have been measured with an isothermal calorimeter at 298.15 K and atmospheric pressure. The values are positive for all the mixtures over the whole composition range. The values increase in the order methanol < ethanol < 1-propanol < 1-butanol. The experimental results have been correlated with the Redlich–Kister equation. 相似文献
15.
S.C. Nunes V. de Zea Bermudez D. Ostrovskii Nuno V. Martins 《Journal of Molecular Structure》2008,879(1-3):72-80
Fourier Transform infrared (FT-IR) and Raman (FT-Raman) spectroscopies and Scanning Electron Microscopy (SEM) were used to investigate ionic association, hydrogen bonding and morphology in a family of sol–gel derived lithium triflate (LiCF3SO3)-doped di-urethane cross-linked poly(ε-caprolactone) (PCL(530))/siloxane hybrid electrolytes. The materials studied, with compositions ∞ > n 0.5 (where n – composition – expresses the molar ratio of PCL(530) ester repeat units per Li+ ion), are non-porous and homogeneous. The Li+ ions interact with the urethane and ester carbonyl oxygen atoms within the whole range of salt concentration analyzed, promoting the formation of hydrogen-bonded aggregates. The composition dependence of the relative concentration of “free” anions and coordinated anions (weakly coordinated anions, ion pairs or [Li(CF3SO3)2]− triplets, aggregates I ([Li2(CF3SO3)]+) and aggregates II ([Li3(CF3SO3)]2+) in all the samples is in perfect agreement with the values of the room temperature ionic conductivity reported previously. 相似文献
16.
Luminescence and luminescence excitation spectra in the vicinity of the optical–optical double resonance transitions to the I2(, vf = 8 and 9, Jf ≈ 55) levels have been measured at the bulb conditions for the I2 + Rg mixtures (Rg = He, Ar, Xe) at the rare gas pressures 2–20 Torr and room temperature. Luminescence attributed to the RgI2 complexes in the ion-pair states has been observed for the first time. It is argued that the complexes can be formed by direct optical excitation from the complexes or colliding pairs. Besides, the RgI2 complexes in the ion-pair states can be formed in nonadiabatic internal conversion processes from the one. The complexes have rather long lifetime, especially in the case of Xe, and decay radiatively and nonradiatively forming I2 molecules in different ion-pair states. 相似文献
17.
The paper presents a new method for predicting the frequency of the b1 mode, which is infrared-inactive, in complexes of the type LM(CO)5 belonging to C4V point group. The method was based on the relation λ3=λ4+[(1−δ/δ)](λ1−λ2), where δ=(λ1−λ2)/(λ1−λ2+λ3−λ4), λ1, λ2, λ3 and λ4 are the λ parameters of the , , b1 and e modes, respectively. For a large numbers of complexes of the type LM(CO)5 the average value of δ was found to be 0.80, with a standard deviation of 0.02. With the use of average value of δ, the frequencies of b1 mode were estimated. The result obtained indicated that there exists a rather good fit between observed and calculated frequencies, with a mean error of 2.7 cm−1. In addition, it was shown that the δ parameter can be used as a criterion of the correct band assignment for the complexes understudy. 相似文献
18.
Dorothy J. Gearhart Katharine L.C. Hunt James F. Harrison 《Journal of Molecular Structure》2008,858(1-3):31-38
The electronic structure of Na2C2 is studied using ab initio electronic structure methods and is compared to the companion molecule Li2C2. Both the linear D∞h and planar structures are minima on the ground state potential surface with the planar D2h conformation being the lowest energy form, similar to Li2C2. At the CCSD(t) level the planar form is more stable that the linear by 11.2 kcal/mol as compared with 7.34 kcal/mol for Li2C2. Both molecules are significantly ionic. The vibrational frequencies, atomization energy at 0 K, D0, and the standard enthalpy of formation, are calculated and compared to those of Li2C2 as well as HCCH, FCCF and ClCCCl. We find D0 and to be 331.1 and 84.92 kcal/mol for Li2C2 and 298.3 and 93.25 kcal/mol for Na2C2. We calibrate these by calculating the same quantities for HCCH, FCCF and ClCCCl. 相似文献
19.
Alvaro Cimas Jos A. Gmez Otilia M Manuel Yez Jean-Yves Salpin 《Chemical physics letters》2008,456(4-6):156-161
A computational study, in the framework of statistical kinetic theories, of the reaction of Ca2+ with urea has been carried out. The kinetically preferred products are NH3 + [CaOCNH]2+, which are the fifth products in order of stability. The second kinetically preferred products are , followed by [CaNH3]2++HNCO, whereas the most stable ones, and , appear only in residual quantities. These estimates are in agreement with the experimental evidence and provide a suitable mechanism to understand the competition between Coulomb explosion and neutral loss processes. 相似文献
20.
Ming Li Jiangfeng Xiang Simin Wu Shuoping Chen Liangjie Yuan Hua Li Hanjiang He Jutang Sun 《Journal of Molecular Structure》2007,840(1-3):119-124
Three new aminodiphosphonates, namely M(phen)(AEDPH3)2·4H2O (M = Zn, (1); Ni, (2)) and Cu(phen)(AEDPH3)2·H2O (4), in addition to the previously reported Co(phen)(AEDPH3)2·4H2O (3), Cu(2,2′-bipy)(H2O)(HEDPH2)·2H2O (5), and Cu(phen)(H2O)(HEDPH2)·2H2O (6) (AEDPH4 = 1-aminoethylidenediphosphonic acid, HEDPH4 = 1-hydroxyethylidenediphosphonic acid, phen = 1,10-phenanthroline and 2,2′-bipy = 2,2′-bipyridyl), have been synthesized and characterized. These compounds are all synthesized at the similar condition (80 °C), whereas they illustrate different frameworks. Compounds 1, 2 and 3 are isomorphous, which contain two same chelate and one six-coordinated metal ion, and display a three-dimensional (3D) supramolecular structure through hydrogen bonds and π–π stacking interactions. Compound 4 contains a chelate and a monodentate , while the Cu ion is five-coordinated. The coordination model of Cu2+ in 4 is similar to that of 5 and 6. Comparing with four aminoethylidenediphosphonates, the difference of their structures is directed to the coordination model of the metal ions, while the three copper(II) diphosphonates illustrate different structures based on the deprotonized degree of the corresponding diphosphonic acids. 相似文献