The matrix isolation infrared spectrum of the hydroxylamine—ammonia complex

The infrared spectra of hydroxylamine and ammonia, co-condensed in nitrogen and argon matrices at ca 20 K, have been observed. A number of bands ha     

The matrix isolation infrared spectrum of the water—ammonia complex

The infrared spectra, in the 4000-200 cm⁻¹ region, of water and ammonia co-deposited in nitrogen and argon matrices have been recorded. The spectra have been interpreted in terms of a linearly hydrogen-bonded 1:1 molecular complex, consistent with the results of gas phase molecular beam electric resonance and infrared spectroscopic studies. Assignments have been made of most of the fundamental vibrations of the complex, and are in general agreement with those published by Nelander et. al. in the same two matrices, as well as in neon and krypton. The wavenumbers measured experimentally have been compared with those calculated in a recent ab initio study, with agreement of the order of 8% for the intramolecular modes of the monomer sub-units and of 16% for the intermolecular modes. The extents to which the water and ammonia monomer spectra are perturbed in the 1:1 complex, and in the linear water and ammonia dimers, have been rationalized on the basis of the relative interaction energies in the three aggregates, and correlated directly with the respective calculated hydrogen bond energies.     

Dichlorosilylene–hydrogen chloride complex: direct IR spectroscopic detection in argon matrix

A 1: 1 donor–acceptor complex between SiCl₂ and HCl was detected by matrix IR spectroscopy. The existence of the complex was previously predicted theoretically in the course of analysis of mechanisms of chemical vapor deposition (CVD) processes involving chlorosilanes. The quantum chemical calculations at the G4(MP₂) level confirmed the possibility of formation of only one stable complex upon the reaction of SiCl₂ with HCl. In addition to the complex of the simplest composition, complexes of SiCl₂ with HCl associates were observed upon matrix annealing. The only product formed upon the photolysis of the complexes of all types was trichlorosilane, a product of silylene insertion into the H–Cl bond.

     

Are matrix isolated species really “isolated”? Infrared spectroscopic and theoretical studies of noble gas-transition metal oxide complexes

In this review, we summarize our recent results on matrix isolation infrared spectroscopic studies and theoretical investigations of noble gas-transition metal oxide complexes. The results show that some transition metal oxide species trapped in solid noble gas matrices are chemically coordinated by one or multiple noble gas atoms forming noble gas complexes and, hence, cannot be regarded as isolated species. Noble gas coordination alters the vibrational frequencies as well as the geometric and electronic structures of transition metal oxide species trapped in solid noble gas matrixes. The interactions between noble gas atoms and transition metal oxides involve ion-induced dipole interactions as well as chemical bonding interactions. Periodic trends in the bonding in these noble gas-transition metal complexes are discussed.     

Spectroscopic influences of ion pairing: Infrared matrix isolation spectra of the M+BF−4 ion pair and its chlorine—fluorine analogs

The matrix isolation technique has been combined with the salt/molecule reaction for the study of contact ion pairs in matrices. The infrared spectrum of the Cs⁺BF⁻₄ ion pair shows a splitting of the triply degenerate BF⁻₄ stretching band due to cesium cation perturbation, with a splitting of nearly 200 cm⁻¹. Normal coordinate calculations support a C_3υ model for the anion, and lead to a value of ΔK of 4.1 for Cs⁺, 4.7 for K⁺ and 3.8 for Tl⁺, where ΔK is the difference in BF stretching force constant between the coordinated fluorine and the non-coordinated fluorines. Similar calculations were carried out for the Cs⁺BCl⁻₄ ion pair, and an optimal value of ΔK = 1.6 was obtained.     

Infrared spectroscopic studies of hydrogen bonded complexes of water with oxygen bases—II. Aliphatic and alicyclic ethers

The i.r. spectra, in the OH-stretching region, of solutions of water at very low concentrations in a number of aliphatic and alicyclic ethers have been recorded. The band envelopes have been resolved into a number of component peaks, and assignments proposed for these components in terms of the hydrogen bonded complexes formed. The wavenumbers, half-widths and intensities of the component bands, and the total hydrogen bonded OH-stretching intensities, have been determined and used as indicators of the relative strengths of the solute—solvent hydrogen bonds. These spectroscopic properties have also been correlated with some of the physical properties of the solvents.     

Infrared and Raman studies of hydrogen bonded complexes involving acetone,acetophenone and benzophenone—II. Raman intensity of the vCO band

The effect of hydrogen bond formation on the Raman intensity of the v_CO band of acetone, acetophenone and benzophenone complexed with phenol derivatives (pK_a = 10.30-7.75) is investigated. The Raman intensity enhancement brought about by complex formation lies between 1.1 and 2.5 and is inversely related to the Raman intensity in the free base. Linear correlations are found between the square root of the intensity enhancement and the enthalpy of complex formation, the intercepts and the slopes depending on the nature of the proton acceptor. The depolarization ratio of the carbonyl band remains practically unchanged. The results are discussed in terms of σ and π electronic densities on the carbon and oxygen atoms of the carbonyl function.     

Infrared spectral studies on the stability of some binuclear transition metal—Schiff base complexes

Some di-Schiff bases like N,N′-o-phenylene-bis-salicylaldimine (DSB₁), N,N′-m-phenylene-bis-salicylaldimine (DSB₂) and N,N′-p-phenylene-bis-salicylaldimine (DSB₃) have been synthesized by the condensation of salicylaldehyde with o-, m- and p-phenylenediamines, respectively. The synthesized complexes of Cu(II), Ni(II) and Co(II) with these ligands have been assigned their molecular structure on the basis of their elemental analyses, molecular weight determination, magnetic measurements, electronic spectra, molar volume and infrared spectral studies. The nature of bonding between metal ion and Schiff bases is studied by i.r. spectrophotometry. The shift in the band position of the groups involved in coordination has been utilized to estimate the coordination bond lengths. The value of the coordination bond length of Cu(II) complexes is shorter than the corresponding values for Ni(II) and Co(II) complexes.     

Studies of hydrogen bonding—XXVII. NMR studies of hydrogen bonding and solvent effect

The OH proton chemical shifts are reported of dilution study of 2-methyl-6-t-butylphenol (2M6TBP) and 2,6-di-t-butylphenol (2.6DTBP), and of the 1:1 association between the phenols and hexamethylphosphoramide (HMPA) in C₆H₁₂, CCl₄, CH₃NO₂, CH₃CN and C₆H₆ at 25, 35 and 50°C. Also the association of the phenols with CH₃NO₂, CH₃CN and CCl₄ has been studied. The phenol OH chemical shift, δ_f, found by extrapolation to zero concentration, shows the highest upfield shift in benzene. Contrary, on adding HMPA, the complex OH chemical shift, δ_x, shows the lowest downfield shift in benzene.The K_ass, δ_x, ΔH and ΔS values have been evaluated by using the Hiquchi plot method. Linear relationships were obtained between Δδ_x and ΔH, and log K_ass for the system 2M6TBP/HMPA in the various solvents. Furthermore, the difference in H-bond energy of a given system in an inert solvent (C₆H₁₂) and in aprotic solvent (CH₃CN), corresponds to the enthalpy of association of the given donor with CH₃CN in C₆H₁₂.The K_ass value for the system 2M6TBP/HMPA is 10 times greater in C₆H₁₂ than in C₆H₆ and CCl₄, 100 times than in CH₃NO₂ and 300 times than in CH₃CN.     

Vapor—liquid equilibria of the binary mixtures methyl chloride — methanol and dimethyl ether — methyl chloride and of the ternary mixture dimethyl ether — methyl chloride — methanol

Vapor Liquid Equilibria in mixtures of dimethyl ether, methyl chloride and methanol were investigated in a static equilibrium apparatus for temperatures 250 K < T <350 K and pressures up to 1 MPa. Temperature, pressure and the composition of the liquid and the vapor phase were determined.The consistency of the binary experimental data was checked and parameters of several g^E-models were fitted. The binary parameters were used to predict the ternary VLE and the calculated results were compared with the experimental data.     

Modeling chemoadaptive behavior: X-ray structure of the trimethylamine oxide-urea (1∶4) complex

The structure of a trimethylamine oxide (TMAO)-urea 14 complex was investigated by x-ray crystallographic methods. C₃H₉NO, 4CH₄N₂O, M_r=315.33, monoclinic P2₁/n, a=11.004(2), b=9.8259, c=15.419(2),=106.88(4), V=1595.4(2) å₃, Z=4, D_x=1.313(1) g cm^–3, monochromatized Cu (=1.5418 å),=8.94 cm^–1, F(OOO)=680, temperature = 110K, final R=0.067, for 1786 unique observed reflections. Based on these studies and comparison with related compounds a model of the interaction of urea and TMAO with proteins, especially enzymes, is proposed. This is important in the physiology of many organisms, especially elasmobranchs. The counteracting effect of TMAO on urea perturbation of protein structure and function is interpreted in terms of water structure as a balance between the structure breaking effect of urea and the structure-stabilizing effect of TMAO.     

Bubble points of hydrogen chloride–water–isopropanol and hydrogen chloride–water–isopropanol–benzene systems and liquid–liquid equilibria of hydrogen chloride–water–benzene and hydrogen chloride–water–isopropanol–benzene systems

Bubble points of the HCl–water–isopropanol and the HCl–water–isopropanol–benzene systems and liquid–liquid equilibria (LLE) of the HCl–water–benzene and the HCl–water– isopropanol–benzene systems were measured at 25–85°C and 30–70°C, respectively. The electrolyte nonrandom two-liquid model proposed by Chen et al. [C.-C. Chen, H.I. Britt, J.F. Boston, L.B. Evans, AIChE J. 28 (1982) 588–596] can satisfactorily correlate bubble points and liquid–liquid equilibria of the present mixed-solvent electrolyte systems over the entire range of temperature and concentrations using only binary adjustable parameters.     

Methanol/n-hexane system—I. Infrared studies

The association constants for different conglomerates of the methanol/n-hexane system are calculated at 303 K from a new i.r. spectra method. The thermodynamic functions, as well as the kind of polymers formed, are calculated for this system and checked with vapour pressure measurements.     

Crystal structure and thermal decomposition mechanism of the supramolecular complex of barium chloride with inositol

The single crystal of [Ba(H2O)2(C6H12O6)2Cl2] was obtained based on the phase equilibrium results. Its structure was determined by X-ray crystallographic analysis. The crystals are monoclinic and in space group C2/c with a=1.901 7(2) nm, b = 0.682 13(8) nm, c = 0.162 60(2) nm,β=96.593(2)°and V= 2.095 3(4) nm3, Z= 4, DC=1.917 g·cm-3. In its solid state, this supramolecular complex is a three-dimensional network with double layers connected by hydrogen bondings. The molecule structure of [Ba(H2O)2(C6H12O6)2Cl2] has a central barium ion that is coordinated to two water molecules, two chlorides, and four hydroxyls from the two inosi-tols. Losing the coordinating water is controlled by random nucleation and growth mechanism (n = 2/3) and 3-dimensional diffusion mechanism (n=2).     

Physicochemical studies of metal haloacetates—VI Infrared spectra of alkaline-earth metals and lead trifluoroacetates

The i.r. spectra of crystalline Mg, Ca and Pb trifluoroacetates have been investigated between 400—300 cm⁻. The trihaloacetate group vibrations are found to be more influenced by the mass and steric hindrance of the CX₃ group as compared to the electron withdrawing ability of the halogens.     

Comparison of the proton and deuteron transfer in the hydrogen (deuterium) iodide—ammonia or trimethylamine systems trapped in argon and nitrogen

Infrared spectra of ND₃/HI, NH₃ or ND₃/DI and N(CH₃)₃/DI mixtures trapped in Ar or N₂ have been recorded in order to complete our previous work [J. Am. chem. Soc. 105, 3843 (1983)] on NH₃/HI and N(CH₃)₃/HI trapped in various matrices. The same matrix effect on the rate of deuteron transfer has been evidenced but the deuteron appears to be significantly more completely transferred than the proton.