Cuprous Halides Research Articles

Comment on "Ground State Structural Anomalies in Cuprous Halides: CuCl"

Comment on "Ground State Structural Anomalies in Cuprous Halides: CuCl"

An NQR Study of Inclusion Compounds Formed Between Small Chlorine-containing Molecules and bis(N-alkylimidazolidine-2-thione)Cu(I) Halide Complexes

Abstract Twenty-five inclusion complexes formed by bis(N-alkylimidazolidine-2-thione)cuprous halides with the small, chlorine-containing guest molecules CCl4, CHCl3, CH2Cl2, CH3CCl3 or C2H2Cl2 , have been prepared. Their 63Cu and 35Cl NQR spectra have been measured over the temperature range 77-300 K. For the corresponding bromides the 79Br and/or 81Br spectra have also been investigated. The studies reveal the number and symmetry of different inclusion site. The onset of rapid reorientation of the guest molecules is indicated by the fading out of their NQR signals between 77 and 300 K, whereas the resonances from the host molecules usually persist throughout this temperature range. However, as evidenced by discontinuities in the temperature-dependence of the NQR frequencies of the hosts, sixteen of the complexes show one or more phase-changes in this temperature-range.

Ground state structural anomalies in cuprous halides: CuCl.

We have examined structural instabilities and elastic anomalies in CuCl via first-principles calculations and find that its crystal structure is not ideal zinc blende but that correlated displacements of groups of four Cu atoms lead to a more stable configuration. About 20% of the Cu atoms are estimated to be affected. The Cu-Cu distance in the C${\mathrm{u}}_{4}$ complex shrinks from 3.82 to 2.72 \AA{}, close to that of metallic Cu. The energetics of defect formation are examined also for CuBr and CuI.

A Molecular Orbital Study of the Selective Adsorption of Simple Hydrocarbon Molecules on Ag+- and Cu+-Exchanged Resins and Cuprous Halides

An extended Huckel molecular orbital (EHMO) study is undertaken for the adsorption of C 2 and C 3 hydrocarbon molecules on highly olefin-selective adsorbents, Ag + - and Cu + -exchanged sulfonic acid resins and copper(I) halides, by using a resin model and different crystal faces of halides. Consideration of the HOMO and LUMO energy levels of the adsorbate and adsorbent can give a qualitative indication of both the direction of electron transfer and the relative bond strength. Quantitative EHMO results show that for π complexation of olefins on resins, the strength of the bond follows the order Ag + > Cu + > H + . The bond strengths of olefins on Cu + exposed on different crystal faces of the halides follow the order (111) > (001) > (111), favoring Cu + with a lower coordination number. A strong anion effect on π-complexation is predicted by EHMO. For C 2 H 4 on the (111) face ofthe copper(I) halides, the bond strength order is CuCl > CuBr > CuI > CuSO 3 C 6 H 5 . The order is reversed for the (001) and (111) faces of the halides. From an analysis of the atomic orbital occupations and the net charges, a quantitative understanding of the π-complexation bond is obtained. The σ donation to the bond is substantially higher than the d-π * back-donation. For the example of C 2 H 4 on AgSO 3 C 6 H 5 , the contribution from σ donation accounts for 84% of the bond, whereas that by the d-π * back-donation accounts for only 16%. The EHMO results are in general agreement with the available experimental data.

Two different in-plane orientations in the growths of cuprous halides on MgO(001)

Heteroepitaxial growths of CuCl and CuBr, zinc-blende-structure ionic compounds, on (001) surfaces of MgO with rock-salt structure have been studied. Textured films of CuCl and CuBr with (111) orientations were grown from molecular beams at a typical substrate temperature of 333 K. We found that CuCl and CuBr had in-plane alignments with respect to the substrate lattice: CuCl[11̄0] was parallel to the MgO[110], [11̄0], [1̄1̄0] and [11̄0] axes; CuBr[11̄0] was parallel to the MgO[100], [010], [1̄00] and [01̄0] axes. This difference is explained by the change in the atomic configurations of the initial nuclei with respect to the substrate lattice arising from a 5% difference in lattice parameter between CuCl and CuBr. An atomic force microscopic observation showed no preferential nucleation of CuCl on step edges appearing on MgO(001). These results strongly suggest an occurrence of the initial nucleation on terraces of MgO(001), not at ledge and kink sites.

Empty states in cuprous halides studied with bremsstrahlung isochromat spectroscopy.

The conduction bands of cuprous halides are studied through bremsstrahlung-isochromat-spectroscopy (BIS) experiments. These results are compared with the densities of states calculated by the linear-muffin-tin-orbital (LMTO) method. The good agreement in the low-energy range permits us to determine the contributions of the different symmetries on the two sites of the three halides. On the higher-energy side BIS, as well as x-ray-absorption spectra, show that the LMTO gives better agreement when they are compared with the p states on copper in CuI than in CuCl.

Structural and magnetic studies on binary mixtures of molten noble metal halides

Neutron diffraction and magnetic susceptibility measurements have been carried out on molten cuprous halides. The structure factors of molten CuBr and CuI show a distinct prepeak caused by a chemical ordering effect. The structure of molten CuBr and CuI is interpreted in terms of local configurations similar to those in the solid phase. The magnetic susceptibilities of the molten CuCl x Br 1− x , CuCl x I 1− x and CuBr x I 1− x systems have been measured by using the Curie-Faraday method. The molten systems of CuCl-CuI and CuBr-CuI obey the Wiedemann rule, while the molten CuCl-CuBr system exhibits a large deviation.

Diamagnetic Properties of Molten Cuprous Halides and Their Mixtures

The magnetic susceptibilities of molten cuprous halides and their mixtures have been measured as a function of temperature. The temperature dependence of susceptibilities in molten CuBr and CuI show small paramagnetic deviations compared to those in molten potassium halides. The composition dependence of CuCl–CuI and CuBr–CuI melts obey the Wiedemann rule, while the molten CuCl–CuBr system exhibits a large deviation from this rule.

Splice Method in the EXAFS Analysis Applied to Cuprous Halide

The splice method in the EXAFS analysis, which was recently proposed for the direct determination of a radial distribution function (RDF), was applied to the systems with large disorder. The 4th-order cumulant expansion method cannot reproduce a strongly asymmetric RDF, while the splice method successfully gives the original RDF. Temperature dependence of the 1st nearest neighbor Br-Cu RDF in CuBr was investigated by analyzing the Br K-edge EXAFS with the splice method.

EXAFS Measurement of Molten Cuprous Halides

EXAFS measurement of molten CuCl and CuBr has been carried out near the melting temperatures in order to study the partial structure. EXAFS oscillation was clearly observed and the structural parameters for the nearest neighboring Cu-halogen pairs were obtained from standard curve fit analyses. The obtained Cu-halogen distance is, however, about 0.1A shorter than the distance obtained from neutron diffraction measurement with isotopic substitution. The result may suggest cluster formation such as a CuX trimer (X = Cl, Br) in molten cuprous halides.

Nuclear magnetic resonance chemical shifts in alkali iodides, cuprous halides and silver halides

NMR chemical shifts of 63Cu, 65Cu, 35Cl, 79Br and 127I nuclei in cuprous halides (CuCl, CuBr and CuI) and silver halides (AgCl, AgBr and AgI) were determined accurately at 294 K using magic-angle-spinning of the sample. The mechanisms of the chemical shifts are discussed qualitatively in terms of the ionic radii and electronegativities. We propose four factors determining the chemical shifts; the nearest neighbor interaction, the next nearest neighbor interaction, isolation and the covalency effect. Temperature dependences of the metal and halogen chemical shifts in alkali iodides, cuprous halides and silver halides were measured for static samples. Positive temperature dependences are observed in LiI ( 7Li and 127I), NaI ( 23Na and 127I), cuprous halides (halogen nuclei), and AgI ( 127I). On the other hand, the dependence is negative in KI ( 39K and 127I), RbI ( 87Rb and 127I), CsI ( 133Cs and 127I), cuprous halides ( 63Cu), AgCl ( 35Cl), and AgBr ( 79Br). These temperature dependences are interpreted qualitatively in terms of lattice vibration, lattice expansion and cation motion.

Preparation and Cu+‐Ion‐Conducting Properties of the Glasses in the System CuBr–Cu2MoO4–Cu3PO4

Cu+‐ion‐conducting glasses were prepared in the pseudoternary system CuBr–Cu2MoO4–Cu3PO4, and the ion‐conducting properties of the glasses obtained were compared to those of the glasses in the system CuI—Cu2MoO4—Cu3PO4, which contain CuI instead of CuBr. The CuBr—Cu2MoO4—Cu3PO4 glasses showed high ion conductivities in the range of 100 to 10−2 S · m−1 at room temperature. The change in ion‐conducting properties caused by the substitution of PO3‐4 anions for MoO2−4 anions was larger than the change caused by the substitution of Br− anions for I− anions in the glasses containing a constant amount of the cuprous halides.

Use of Harrison's potential in ZnS, NaCl and CsCl-structure solids

Harrison's overlap repulsive potential has been used for evaluating cohesive energies, bulk modulus and its pressure derivatives, Gruneisen parameter, and the volume derivatives of Gruneisen parameter for cuprous halides, silver halides and thallous halides. This potential has replaced the old and widely used Born-Mayer potential in ionic crystals. The Harrison repulsive potential has been represented by a quantum mechanical analytical potential form derived from the tight binding theory. The parameters involved in this potential form have been determined in terms of valence state energies of outermost d-electrons of Cu+, Ag+ and Tl+ ions. The results calculated in the present study have been found in good agreement with experimental data and better than those predicted from the Born potential model.

Molar Volume of Molten Cuprous Halides

Molar Volume of Molten Cuprous Halides

High Purity Cuprous and Silver Halides for Synthesis of Halide Glasses

High Purity Cuprous and Silver Halides for Synthesis of Halide Glasses

Polymorphism of allyl cyanide ?-complexes of cuprous halides. Synthesis and structure of a new modification of 2CuCl�C4H5N

Polymorphism of allyl cyanide ?-complexes of cuprous halides. Synthesis and structure of a new modification of 2CuCl�C4H5N

Synthesis and characterization of ( [formula omitted]) and ( [formula omitted])-1,2-difluoroethenediyl bisphosphonates

Cuprous halide mediated decomposition of (diethoxyphosphinyl)difluoromethylzinc bromide, (EtO) 2P(O)CF 2ZnBr, forms the title bisphosphonates in 50% isolated yield. The 19F and 31P NMR spectra of these isomeric bisphosphonates exhibit non-first order AA‘'XX’' patterns. Computer simulation permitted the determination of the J P-F, J F-F, and J P-P coupling constants for these compounds. Silylation and hydrolysis of the bisphosphonate mixture gave the silylated bisphosphonates and bisphosphonic acids respectively, as expected. Metathesis of the zinc reagent also yielded phenyl (diethoxyphosphinyl)difluoromethyl- mercury, (EtO) 2P(O)CF 2HgPh, in good yield. However, attempts to generate fluoro(diethoxyphosphinyl)carbene from this mercurial were unsuccessful.

ChemInform Abstract: Chemistry and Composition of (Trialkylsilyl)cuprates Derived from Cuprous Halides.

Synthese de trialkylsilyl cuprates a partir de dimethylphenylsilyl lithium et de CuBr•He 2 S. Etude de ces cuprates par RMN

Effect of spinning on chemical shifts in magic-angle-spinning nuclear magnetic resonance

We have found that the isotropic peak position changes depending on the spinning rate of the sample in 63Cu, 65Cu, 79Br, and 127I magic-angle-spinning nuclear magnetic resonance (NMR) of cuprous halides, CuCl, CuBr, and CuI. With the increase in the spinning rate, the 63Cu and 65Cu signals shift towards lower frequencies, while the 79Br and 127I signals shift towards higher frequencies. The magnitudes of the frequency shift are in the following order: CuCl<CuBr<CuI, and the shifts in the halogen signals are of comparable magnitudes to those in the copper signals except for the shift direction. The magnitude of the spinning-induced shift is found to be proportional to the square of the spinning rate and to the strength of the magnetic field. We have proposed that the spinning-rate-dependent shift has its origin in the Lorentz force working on Cu+ ions being forced to move fast in a strong magnetic field, and have derived formulas to explain the above phenomena. We have also checked other possibilities, and have concluded that no other mechanisms can explain the above phenomena.

Multiplet Structures of Resonant Photoemission Spectrum in Cuprous Halides

Multiplet structures of the resonant photoemission spectrum are studied in cuprous halides on the basis of an impurity Anderson model. The formation of trion (the bound state of two 3 d -holes and one conduction electron) with multiplet structures is discussed as an origin of sharp satellite peaks coexisting with Auger peaks above the 3 p -core-level photothreshold. It is shown that a small mixing of the d 9 -electron configuration to the d 10 -electron configuration of Cu atom in the ground state is important for non-vanishing intensity of the satellite far below the photothreshold. Halogen's p -levels are found to affect considerably the satellite spectrum through the mixing to Cu's 3 d -levels, leading to the spectral shape of CuCl different from that of CuI.