Application of Kirkwood's theory of the dielectric constant to solutes hydrogen-bonded in the water network

In a quasi-thermodynamic treatment, the partial molar polarization of a solute in a network liquid is expressed in terms of dipole moments, molalities. Kirkwood's formal correlation factors, and solute-induced changes in the correlation factors. The formal correlation factors are then resolved into explicit terms for solvent-solvent, solvent-solute and solute-solute dipole correlation, which convey specific (though limited) information about the stoichiometry and geometry of the respective hydrogen-bonding. Experimental partial molar polarizations are analyzed for aqueous solutions of p-dioxane, pyrazine, quinoxaline, acetone, pyridine, N,N,N,N-tetramethylurea, acetonitrile, and dimethylsulfoxide. The treatment does not yield unique hydrogen-bonded structures but, when combined with other evidence, it greatly limits the possibilities. Water molecules appear to donate hydrogen bonds exhaustively to ether and carbonyl oxygen atoms, and to aza-aromatic nitrogen atoms. Water molecules also appear to donate hydrogen bonds to aza-aromatic -systems, and to the triple bond in acetonitrile.     

Preparation and characterization of Mg(II)-, Ca(II) and Cd(II) complexes of 1,2-ethanediol and water

Mixed ligand complexes of different compositions were prepared with water, sulfate ion and 1,2-ethanediol as ligand. IR spectra and the thermoanalytical curves of the complexes were recorded. Oxygen atoms bound by one or two coordinate bonds to the metal ion, or by hydrogen-bonds in the crystal, were observed. As for the water molecule, 1,2-ethanediol molecules of crystal and monohydrate type were found, depending on the type of binding of the oxygen atoms.This revised version was published online in November 2005 with corrections to the Cover Date.     

Physico-chemical properties of charge transfer complexes of ferrocene and 1,1′-dimethylferrocene in methanol and cyclohexane

Summary In liquid systems, ferrocene and its 1,1-dimethyl derivative, (MeCp)₂Fe, give charge transfer complexes with C(NO₂)₄ in which the metallocene is an electron donor. The spectral absorption maxima of the complexes were established and the values of their molar extinction coefficients, _CT, equilibrium constants, K, and heats of formation, H, were determined.     

Molecular polarizability of organic compounds and their complexes: L. Molar volumes and steric structure of some schiff bases and their structural analogs in infinitely dilute solutions

Molar volumes of a wide series of Schiff bases and their structural analogs, such as N-benzyl-ideneaniline N-oxides and azo compounds, in infinitely dilute solutions were determined. Analysis of the obtained values in terms of the additivity scheme showed that molecular fragments and substituting groups in these compounds are strongly solvated by solvent molecules, which leads to deviation of most molecules from the planar arrangement of the aryl moieties and bridging groups. Most compounds in which H-chelate rings are formed due to intramolecular hydrogen bonding are characterized by contraction of molar volumes, indicating their entropy stabilization in solution via release of solvent molecules from the solvate shell upon chelation. Methods for the determination of dipole moments and Kerr constants in solution can be simplified to a considerable extent for those compounds for which the additivity scheme was applied to calculate the molar volumes.     

Thiacalix[4]arene-alkali metal assemblies: crystal structures and guest-binding capabilities of supramolecular architectures supported by metal coordination and cation-π interactions

To investigate alkali metal complexation with sulfur-linked calixarene analogues and their guest-binding properties for gaseous organic guest molecules, we elucidated a crystal structure of a cesium complex with p-H-thiacalix[4]arene (1·4H) ligands and guest-binding properties of the cesium complex (2) and the previously reported rubidium complex (3). In crystals of the complex 2, a ‘sandwich-like’ binuclear complex was formed by inter-molecular coordination of cesium cations to the thiacalixarene molecules and methanol molecules, mutually interacting by aromatic-H?S hydrogen bonding and alkali metal cation-π interactions between the alkali metal cation and thiacalixarene aromatic rings outside of the cavities. On the guest-binding behaviors both complexes 2 and 3 toward organic guest molecules, methanol, ethanol, and 1-propanol as polar molecules, the complex 2 has no methanol adsorption ability, but the complex 3 showed vapor adsorption properties for all guest molecules. In particular, both complexes exhibited a high adsorption capability toward ethanol molecule. As results of gaseous guest adsorption measurements for alcohol molecules, the guest-binding of these complexes are significantly different because the properties depend heavily on structural natures between complexes 2 and 3.     

Molecular polarizability of the organic substances and their complexes: LX. Molecular volume and spatial structure of the series of heterocycles, their structurally nonrigid derivatives, and chromium tricarbonyl π-complexes in solutions

We have analyzed the molar volumes and structures in solutions of a series of azines, azoles, conformationally nonrigid bis(2-substituted benzimidazol-1-yl)methanes, and chromium tricarbonyl complexes of arenes. For most of the compounds, the rules of molar volume additivity with respect to the bonds and groups increments hold. Molecules of bis(2-substituted benzimidazol-1-yl)methanes exist in the form of conrotatory comformers with aryl fragments being out of the plane of bridging NCN bond angle. Strong linear correlations between the molar volume and molar refraction have been revealed within the studied compounds classes. In the case of chromium tricarbonyl complexes of arenes, the coordination bond polarity has increased with growing π-donor ability of the ligand, the molar volume increment of Cr(CO)₃ has increased as well, due to transfer of π-electron density from the ligand. The simplification of dipole moment and Kerr constant determination has been demonstrated.     

Cyclopalladation of carborane tertiary amines

Conclusions Starting from, tertiary amines of the carborane series, cyclic complexes with B-Pd bonds have been obtained, which give insertion products with two molecules of diphenylacetylene, at the B-Pd bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, 1646–1649, July, 1984.     

Microscopic Models for Proton Transfer in Water and Strongly Hydrogen-Bonded Complexes with a Single-Well Proton Potential

A new mechanism and formalism for proton transfer in donor-acceptor complexes with long hydrogen bonds introduced recently [1], is applied to a proton transfer in liquid water. Structural diffusion of hydroxonium ions is regarded as totally adiabatic process, with synchronous hindered translation of two closest water molecules to and from the reaction complex as crucial steps. The water molecules induce a gated shift of the proton from the donor to the acceptor in the double-well potential with simultaneous breaking/formation of hydrogen bonds between these molecules and the proton donor and acceptor. The short-range and long-range proton transfer as structural diffusion of Zundel complexes is also considered. The theoretical formalism is illustrated with the use of Morse, exponential, and harmonic molecular potentials. This approach is extended to proton transfer in strongly hydrogen-bonded donor-acceptor complexes. In contrast to the above model [1], the short hydrogen bond between the donor and acceptor moieties, however, completely erodes the barrier along the proton transfer mode. This introduces some physical pattern differences from proton transfer reactions in truly double-well potentials with a finite proton transfer barrier at the transition configuration with respect to the environmental nuclear coordinates. The differences apply particularly to the origin of the kinetic isotope effect. We discuss explicitly details of the excess proton conductivity in aqueous solution, but the concepts and formalism apply broadly to acid-base reactions, proton conduction channels, and other strongly hydrogen-bonded O- and N-proton donor-acceptor systems.     

Conformational analysis of 2-substituted 1-nitro-and 1-bromo-1-nitroethenes

Conformational analysis of 2-trichloromethyl(ethoxycarbonyl)-1-nitro-and 2-trichloromethyl-(ethoxycarbonyl)-1-bromo-1-nitroethenes was performed using the dipole moment method, IR spectroscopy, and DFT quantum-chemical calculations (B3LYP/6-31G*). The nitro and ester (or trichloromethyl) groups in the molecules of these compounds were found to occupy trans positions with respect to the double C=C bond, i.e., the nitroalkenes have E, and their bromine-containing analogs, Z configuration; the compounds having an ethoxycarbonyl group are characterized by s-cis orientation of the C=C and C=O bonds.     

Absorption spectra and bond characteristics of Ni(II) aquoamino complexes

The spectra of five aquoamino complexes have been established by resolving the observed absorption spectra of solutions containing salts of Ni(II) and ammonia. These spectra have been used to deduce the parameters of the bonds on the assumption of octahedral symmetry. The antibonding and nepheloxet effects are found to be nonadditive and nonlinear; the behavior can be explained on the basis of the interaction between the central ion and the water molecules.     

Diffuse-Reflectance IR Spectra of Methane Adsorbed on NaZSM-5 and HZSM-5 Zeolites

Diffuse-reflectance IR spectra of methane adsorbed on high-silica NaZSM-5 and HZSM-5 zeolites point to a stronger adsorption of methane on sodium cations than on protons. For the asymmetric stretching vibration ₃, this form of adsorption is characterized by a doublet with band maxima at 2980 and 3010 cm^–1. For the fully symmetric stretching vibration ₁, it is characterized by a singlet with a maximum at 2880 cm^–1. Methane is also adsorbed on NaZSM-5 in a weaker form, which is characterized by absorption bands with maxima at 3002 (₃) and 2887 (₁) cm^–1. The weaker form of methane adsorption on acidic bridging hydroxy groups of HZSM-5 is characterized by absorption bands at 3001 and 2887 cm^–1 (₃ and ₁, respectively). A difference between this form of adsorption and weak adsorption on sodium-exchanged zeolite reveals itself in the somewhat higher intensity of the band at 2887 cm^–1. For methane adsorbed on NaZSM-5, the frequencies of deformational vibrations and a spectrum in the near IR region are obtained for the first time. It was found that the perturbance of adsorbed methane molecules is seen in the spectrum as in the low-frequency shifts of most of the bands that appear due to composite vibrations and overtones and as new adsorption bands that were not observed for gaseous methane.     

Real‐space grid representation of momentum and kinetic energy operators for electronic structure calculations

We show that the central finite difference formula for the first and the second derivative of a function can be derived, in the context of quantum mechanics, as matrix elements of the momentum and kinetic energy operators on discrete coordinate eigenkets defined on a uniform grid. Starting from the discretization of integrals involving canonical commutations, simple closed‐form expressions of the matrix elements are obtained. A detailed analysis of the convergence toward the continuum limit with respect to both the grid spacing and the derivative approximation order is presented. It is shown that the convergence from below of the eigenvalues in electronic structure calculations is an intrinsic feature of the finite difference method. © 2018 Wiley Periodicals, Inc.     

Derivative spectrophotometric determination of holmium in rare earth mixtures with 2-(diphenylacetyl)indan-1,3-dione and octylphenyl poly(ethyleneglycol) ether

The zero-order and second-order derivative absorption spectra of the system of holmium with 2-(diphenylacetyl) indan-1, 3-dione and octylphenyl poly(ethyleneglycol) ether have been determined by derivative spectrophotometry. The molar absorptivity of absorption spectra and the derivative spectra are calculated respectively. The absorbances at the absorption maxima for the holmium complex are 48.5 (at 450 nm) and 14.5 (at 460 nm) times greater than for the corresponding chloride. The derivative spectra have been used to eliminate the interference of other lanthanides, and the sensitivity is again increased by a factor of about 5. The calibration graph is linear up to 25 g/ml of holmium. The detection limit, obtained from the sensitivity of the calibration graph and for 3S _b (S_b = standard deviation of a blank without holmium,n = 11), was 0.37 g/ml of holmium. The quantification limit (10S_b was 1.2 g/ml. The method has been applied successfully to synthetic and reference samples of rare earths.     

Ring pucker in dihydroaromatic epoxides: The molecular structure ofr-1-hydroxy-t-2-methyl-t,t-3,4-epoxy-1,2,3,4-tetrahydronaphthalene

The crystal structure of the derivative of tetrahydronaphthalene with substituent epoxy, hydroxyl, and methyl groups in the more saturated ring (r-1-hydroxy-t-2-methyl-t,t-3,4-epoxy-1,2,3,4-tetrahydronaphthalene) has been determined. The hydroxyl and methyl groups are both found to beequatorial. The crystal structure is characterized by chains of molecules linked by O-H O hydrogen bonds involving the hydroxyl groups; these hydrogen bonds lie approximately parallel to theb axis. The conformations of the epoxide-bearing rings in various hydroxy epoxides are compared and shown to be similar.     

Optical and Chromaticity Characteristics of Arsenazo III Complexes of Rare-Earth Elements

Optimal conditions for the complexation of La, Nd, Sm, Tb, Dy, Gd, Ho, Er, and Yb ions with Arsenazo III were found, and molar absorptivities of the complexes were calculated. Chromaticity characteristics of the complexes were determined. The coefficients of calibration plot equations and molar coefficients of chromaticity functions were calculated for the concentration range 10–50 g of rare-earth element per 25 mL of solution. It was demonstrated that the use of the most sensitive chromaticity functions increases the sensitivity of the reaction by 1.5–2 orders of magnitude compared to the photometric method.     

Synthesis,characterization and antimicrobial activity studies of N - N ′-tetracarboxydiethyloxamide ligand and its metal(II) complexes

N-N′-tetracarboxydiethyloxamide (hereafter abbreviated as H₆L) was prepared by using L-aspartic acid and diethyl oxalate (DEO). A series of binuclear complexes of divalent metal chlorides viz. Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with H₆L have been prepared. Spectral studies (IR, UV and NMR) magnetic susceptibility, elemental analysis and molar conductance measurements confirm the formation of binuclear complexes, [M₂H₂L]/[M₂H₂L?·?4H₂O]. Electronic absorption spectra and magnetic susceptibilities suggest square-planar stereochemistry for Cu(II) and tetrahedral for Zn(II) complexes. Mn(II), Co(II), and Ni(II) coordinate two molecules of water and consequently show octahedral geometry. The in vitro antimicrobial activity of the synthesized compounds is discussed against bacterial strains such as S. aureus, S. epididermis, K. pneumonia, S. typhi, P. aerugenosa, and B. subtilis A. brasilense. The metal complexes show higher activity against all the microorganisms than the ligand.     

Importance of the Debye interaction in organic solutions: Henry's law constants for polar liquids in nonpolar solvents and vice versa

Henry's law constants have been determined for -butyrolactone (BL), ethyl acetate (EA), and 2-methyl-3-pentanol (MEP) in mixtures of iso-octane (ISO) and toluene (TOL), for BL, EA, TOL, and ISO in cinnamaldehyde (CIN) and for TOL and ISO in each other and in BL. From these data and published vapor pressures, the activity coefficients at infinite dilution and the standard molar Gibbs free energy of transfer, G ₂ ⁰ of the solutes from dilute solution in ISO to dilute solution in each solvent medium have been calculated. The different behavior patterns of BL and EA are attributed to differences in their abilities to exist in different conformations possessing different dipole moments. For polar solutes, G ₂ ⁰ decreases with increasing polarizability of the solvent and with increasing dipole moment of the solute, suggesting increased contributions from dipole-induced dipole (Debye) interactions. The sigmoidal plot of G ₂ ⁰ against the change in pair potential energy calculated from the classical expressions suggests that G ₂ ⁰ seriously underestimates the strength of the Debye interactions in comparison with the London interactions.     

Collision-induced absorption of infrared radiation by N2, O2 and CO2

The collision-induced absorption of the symmetric vibration of CO₂ has been observed in the pure gas at densities from 20.0 to 40.0 amagat and at temperatures of 273, 298, and 323 K using infrared techniques. From the integrated intensities of the bands and using the (exp ?4) model of van Kranendonk, it is possible to deduce a value for the first derivative of the quadrupole moment with respect to the vibrational coordinate. For CO₂ the contribution from quadrupole distortion to the binary absorption coefficient is reported for several temperatures. The (exp ?4) model of van Kranendonk is used to calculate the binary absorption coefficients for the fundamental vibrational bands of N₂ and O₂ at temperatures from 70 to 340 K. The parameters λ and p/σ describing the magnitude and range of the short-range collision-induced dipole moments were determined using the known experimental absorption coefficients. The contributions from atomic distortion and quadrupole distortion to the binary absorption coefficient are calculated for N₂ and O₂.     

Photochemical properties of ferrocene,cobaltocene and nickelocene and their complexes with 2,2,2-trichloroethanol in liquid phase

Summary Photochemical changes in the solutions of ferrocene, cobaltocene, nickelocene and their complexes with 2,2,2-trichloroethanol exposed to near u.v. and argon laser (=514.5 nm) radiation were investigated. The solutions of cobaltocene, nickelocene and their complexes were found to undergo photolysis, whereas ferrocene solutions are not sensitive to this kind of irradiation and the ferrocene bound in a complex undergoes photooxidation to give the ferricenium cation. The activating effect of laser irradiation of ferrocene was revealed as a tendency to complex formation. The quantum yield of the investigated photoreactions, equilibrium constant of complex formation,K, and their molar extinction coefficients, _c, were determined.