Molecular polarizability of organic compounds and their complexes: LIII. Molar volumes in solutions and steric structure of molecules of polyaryl compounds with bridging groups containing sp 2-and sp 3-hybridized carbon

The molar volumes of polyphenylmethanes, polyarylethanes, polyaryl compounds based on pyridinium cations, polyarylethylenes, and also diaryl and hetaryl ketones in various solvents were determined. Additive analysis of the molar volumes of these compounds showed that the aryl rings in their molecules are acoplanar to the bridging groups in which these rings can rotate about single bonds. The most probable is the conrotatory model of mutual orientation of the aromatic rings relative to each other. This orientation is similar to that found previously in solutions of such molecules as diphenylmethane, benzophenone, and some others, according to data of various physical methods. The possibility of substantial simplification of methods for determining the dipole moments, Cotton-Mouton constants, and Kerr constants for the compounds under consideration was demonstrated.     

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.     

Molecular polarizability of organic compounds and their complexes: XLIX. Molar volumes of polyaryl systems in solutions, extrapolated to infinite dilution, their additivity, and steric structure of the molecules

Molar volumes of a number of polyaryls and of several model systems at infinite dilution in carbon tetrachloride and benzene were determined. The molar volumes of the compounds under study are additive by bonds, groups, and molecular fragments. The dipole moments and Kerr molar constants of the compounds under study can be found by a simplified additive method. As follows from the additive analysis of the molar volumes of diphenyl, para-substituted diphenyls, heteroaromatic analogs, and a number of polyaryls, the molecules of these compounds are acoplanar in the solutions, and the degree of their acoplanarity is the same as in diphenyl.     

Molecular polarizability of organic compounds and their complexes: LVI. Molar volume and structure in a solution of the compounds with several axes of intramolecular rotation

Molar volumes in solutions of compounds like orthoformic esters, trialkyl phosphates, trialkylphosphites, substituted aziridines, cyclopropanes, cyclohexanes, boroxines, N-aryl-4-pyridones, decalines, and cyclooctane were determined and discussed. Conformations of alkyl substituents in the esters were found to be similar to the conformations of the corresponding alkanes. Molar volumes of aziridines and cyclopropanes were found to be additive with respect to the molar volumes of bond and group increments. The nature of solvation of the molecules of these compounds was found to be similar to that in the model systems which served for the calculations of the increments. Molar volumes of cyclohexane, decaline, and cyclooctane also were found to be additive with respect to the contributions of the molar volumes of increments of the corresponding bonds and groups. The solvation and the steric structure of substituted boroxines were found to be similar to those of the structurally analogous substituted benzenes. Conformations of N-aryl-4-pyridone and its substituted derivatives in solutions were found to be similar to the conformations of biphenyl and its derivatives. A possibility of simplification of the methods for determining the dipole moments and Kerr constants of compounds from their additive molar volumes was demonstrated.     

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.     

Molecular polarizability of organic compounds and their complexes: LI. Molar volumes and steric structure of intracomplex compounds in solutions at infinite dilution

Molar volumes in solutions at infinite dilution were determined for a series of intracomplex compounds of beryllium, zinc, cobalt, copper, and nickel, derived from salicyalalanilines, salicylalalkylimines, N-[(2-hydroxyphenyl)(methyl)methylene]anilines, N-[(2-hydroxyphenyl)(phenyl)methylene]aniline, as well as ethylene glycol and glycerol. An additivity scheme was constructed for calculation of the molar volumes of these compounds in solutions. Analysis of the experimental molar volumes of the systems studied showed that chelation via intramolecular complex formation almost always makes these values lower than those calculated by the additivity scheme, implying entropy stabilization of the chelates in solutions due to release of solvent molecules from the solvation shell of the molecules. It was shown that the dipole moments and Kerr constants of those compounds for which the additive scheme for calculation of molar volumes was constructed can be much easier estimated.     

Molar volumes of the KKI and KKCl molten solutions

Molar volumes in molten solutions of KKI at 973 and 1073°K and KKCl at 1073°K in the molar fraction range of 0-0.2, were determined by a gamma ray absorption method. For both systems the excess volumes were equal to zero which is consistent with theoretical considerations by Katz and Rice for alkali metal - molten salt solutions.     

Molecular polarizability of organic compounds and their complexes: LII. Molar volumes of polymeric compounds in solutions,extrapolated to infinite dilution,and steric structure of their molecules

The molar volumes in solutions at infinite dilution were determined for a series of vinyl, glycol, isoprene, and cyclopentadiene polymers and oligomers with various degrees of polymerization. An additive analysis of the molar volumes showed that molecules of vinyl, ethylene glycol, and isoprene polymers exist in solutions in elongated helical conformations. In the majority of polymer molecules, except polystyrenes, polyisoprenes, and polycyclopentadienes, there are randomly disordered regions creating additional volumes inaccessible to solvation with solvent molecules. Cyclopentadiene oligomers formed by the Diels-Alder reaction have in solution the conformation of corrugated bands. The additive scheme for calculating the molar volumes considerably simplifies the determination of the dipole moments and Kerr constants of the compounds for which this scheme has been constructed.     

Molar and Partial Molar Excess Volumes of Benzene in Methyl Ester Solutions at 25°C

Molar and partial molar excess volumes of mixtures of benzene with several methyl esters (from methanoate to decanoate) were determined, over the whole concentration range, at 25°C and atmospheric pressure from experimental densities and correlated by a suitable equation. The applicability of the Flory and Priggogine–Flory–Pattersort models for predicting molar excess volumes is tested. The calculated values with Flory and Priggogine–Flory–Patterson are similar and agree poorly with the experimental data.     

Molecular polarizability of organic compounds and their complexes: LIX. Molar volumes, intrinsic atomic solvation radii, and spatial structures of certain conformationally flexible compounds in solutions

The molar volumes and structures in individual liquids and solutions of a series of conformationally flexible compounds, such as alkanes and diaryl-substituted systems with sp ³-hybridized bridging atoms, were analyzed in terms of intrinsic solvation radii of atoms constituting the molecule. Intrinsic solvation atomic radii were determined for various molecules to show that they are larger than the van der Waals radii of the same atoms. An approach to parametrization of the intrinsic solvation radii of atoms constituting a molecule, using appropriate model compounds, was proposed. From the resulting values of intrinsic atomic solvation radii, the possible conformations of a series of diphenylmethanes, diphenylsilanes, diphenyl sulfides, diphenyl sulfoxides, and diphenyl sulfones in solutions were assessed.     

Particle bridging in dispersions by small charged molecules: chain length and rigidity, architecture and functional groups spatial position

The particle bridging behaviour of dicarboxylic acid bolaform compounds such as fumaric, oxalic,trans-beta-hydromuconic, trans,trans- and cis,cis-muconic acids were evaluated in terms of their effects on the yield stress of alpha-Al(2)O(3) dispersions. The adsorption behaviour of these additives and their effects on the particle zeta potential were also determined. This study aims to understand and identify molecular factors essential for particle bridging. Very rigid compounds like trans,trans- and cis,cis-muconic and fumaric acids were identified as excellent bridging compounds from the large increase in the maximum gel strength. This strength enhancement increases with chain length and is due to more bridging molecules located in the larger spherical cap bridging area and participating in bridging. Cis,cis-muconic acid with the same chain length as fumaric acid displayed a greater bridging capability as its bolaform carboxylate groups possessed a greater lateral reach. Trans-beta-hydromuconic acid with a more flexible backbone displayed a much diminished particle bridging capability. This study has revealed a number of new molecular structural factors essential for particle bridging attribute. These are (a) the degree of backbone rigidity, (b) chain length, (c) spatial position and (d) lateral displacement of the bolaform charged group. For fumaric, trans,trans- and cis,cis-muconic acids, the maximum gel strength was not located at the pH of zero zeta potential. A particle bridging model taking into account of electrostatic repulsive interactions between the interacting particles was proposed to explain the maximum gel strength enhancement by the bolaform compounds.     

Study of some volumetric and refractive properties of {PEG 300 (1) + ethanol (2)} mixtures at several temperatures

Molar volumes and excess molar volumes were investigated from measured density values for {PEG 300 (1) + ethanol (2)} binary mixtures at temperatures from 278.15 to 313.15 K. Both systems exhibit negative excess volumes probably due to increased interactions like hydrogen bonding and/or large differences in molar volumes of the components. Volume thermal expansion coefficients were also calculated for both binary mixtures and pure solvents. Refractive indices were also determined for all these non-aqueous mixtures and neat solvents at all temperatures. Furthermore, the Jouyban–Acree model was used for density, molar volume and refractive index correlations of the studied mixtures at different temperatures. The mean relative deviations between experimental and back-calculated density, molar volume and refractive index data were 0.07%, 0.99% and 0.01%, respectively.     

Volumetric Properties of Glycerol Formal + Propylene Glycol Mixtures at Several Temperatures and Correlation with the Jouyban–Acree Model

Molar volumes, excess molar volumes, and partial molar volumes were investigated for glycerol formal + propylene glycol mixtures from density measurements at temperatures from (278.15 to 313.15) K. Mixture compositions were varied in 0.05 in mass fraction of both components. Excess molar volumes were fitted to the Redlich?CKister equation and compared with literature values for other systems. The system exhibits positive excess volumes probably due to increased non-specific interactions. The effect of temperature on the different volumetric properties studied was also analyzed. In addition, the volumetric thermal expansion coefficients were calculated. The Jouyban?CAcree model was used for density and molar volume correlations of the mixtures at the different experimental temperatures. The mean relative deviations between experimental and calculated data are 0.04±0.03 and 0.04 ±0.05, respectively, for the density and molar volumes, using the minimum number of data points, the Jouyban?CAcree model can predict density and molar volume with acceptable accuracies (0.06±0.04 and 0.08±0.05, respectively).     

Molar excess volumes of 1,4-dioxane+ acetonitrile,n-butylamine+acetonitrile andn-butylamine+1,4-dioxane at different temperatures

Molar excess volumes and partial molar volumes are reported for binary mixtures of 1,4-dioxane + acetonitrile, n-butylamine + acetonitrile and n-butylamine + 1,4-dioxane at five different temperatures and over the complete concentration range. The Prigogine-Flory-Patterson model of solution thermodynamics has been used to predict the excess molar volumes. This work shows the importance of the three contributions: interactional, internal pressure and free volume, to the excess volume.     

Molar and partial molar excess volumes of di-n-butylamine with chloroalkanes at 25°C

Molar excess volumes and partial molar excess volumes are reported for binary mixtures of dibutylamine+dichloromethane, trichloromethane and tetrachloromethane at 25°C, over the whole concentration range. A comparative study is made between the primary and secondary amines and their mixtures with chloroalkanes. The applicability of the so-called ERAS model for predicting thermodynamic excess properties is tested here for excess molar volumes; the calculated values agree quite well with experimental data.     

Group IB organometallic chemistry: XXXV. Crystal and molecular structure of [Cu4(4-MeC6H4)-MeC-C(C6H4NMe2-2)2(C6H4NMe2-2)2], a tetranuclear organocopper compound containing bridging alkenyl and aryl groups

The crystal and molecular structure of the title compound has been determined by a single crystal X-ray diffraction study using standard Patterson and Fourier methods. The structure was refined by a block-diagonal least-square procedure to a finalR value of 0.16 for 3454 reflections. Crystals are monoclinic, space groupP2₁/c, witha 14.007(5), b 12.224(5), c 28.358(8)A?, β 99.60(1)°, andZ - 4.The molecule consists of a central rhombus-type core of copper atoms to which the alkenyl and aryl groups are bound in a bridging fashion (two electron-three center bonding). The two alkenyl and the two aryl groups each occupy adjoining edges of the Cu₄ core. The dimethylamino groups of the alkenyl ligand coordinate to copper, whereas those of the bridging aryl ligand are free. As a result the copper core is made up of copper atoms which are alternatingly two- and three-coordinate.The structure is discussed in terms of structural information now available for organocopper compounds. The geometry of the Cu₂C (bridge) moiety in organocopper cluster compounds as expected varies little with the nature of the bridging one-electron organo ligand (alkyl, alkenyl, alkynyl or aryl).     

Partial Molar Volumes and Heat Capacities of Some Analogs of Acyclovir

We have investigated acyclovir and eleven of its analogs modified in the base moiety (bicyclic and tricyclic) and ganciclovir, an analog modified in the acyclic chain. Partial molar volumes and heat capacities of aqueous solutions of five of these compounds were determined from acyclovir; density measurements are reported here. The dependence of the partial molar quantities on the number of substituted CH₂ groups were determined. For all compounds, the values of V^o₂ were evaluated by using a simple scheme of group contributions. The structural parameters of these compounds were determined by the SYBYL (Tripos, USA) package. Molecular volumes, volumes of solvation shell, as well as molecular surface areas and their atomic partition were calculated with the aid of GEPOL Version 12.1. From these data, the relative densities of the solvation shells characterizing the structure of the solvent around the solute molecules were obtained. The polarity, defined as the ratio of the surface of polar groups and atoms exposed to the solvent to the total molecular surface of the molecule studied, was evaluated. Linear dependencies were found between the densities of solvation shells and the polarity which permitted the relative densities of solvation shell is to be found.     

Reaction of diarylzinc compounds with copper(I) salts. Synthesis and characterization of arylcopper(I) compounds

The reaction of diarylzinc compounds with copper(I) salts is an excellent way of preparing stable arylcopper compounds in quantitative yields. These compounds have been characterized by IR, and by ¹H and ¹³C NMR spectroscopy. Cryoscopic molecular weight determinations show phenylcopper to be polymeric and 2-methylphenylcopper and 2,6-dimethylphenylcopper to be tetrameric in benzene. The compounds are believed to contain aryl groups bridging two copper atoms. Evidence is presented for rotation of these aryl groups around the C(1)—C(4) axis.     

Excess thermodynamic properties of binary mixtures of n-Alkanes with cycloalkanones

Molar excess enthalpies of the systems cyclopentanone/n-alkanes and cyclohexanone/n-alkanes at 298.15 K were determined by direct calorimetric measurements. Molar excess volumes of cyclopentanone and cyclohexanone/n-alkanes were determined at 298.15 and 308.15 K and of cycloheptanone/n-alkanes at 298.15 K by dilatometric measurements of volumes of mixing. The excess thermodynamic properties for a particular cycloalkanone increase with the chain length of the n-alkane, while for a given n-alkane, excess properties decrease as the size of the cycloalkanone increases.