Showing papers on "Isostructural published in 1972"

Luminescence and Structural Properties of Thiogallate Phosphors Ce+3 and Eu+2‐Activated Phosphors. Part I

Abstract: Thiogallate compounds represented by the formula were prepared by solid‐state reaction. Single crystals of the alkaline earth derivatives were also obtained by vapor transport of the corresponding polycrystalline material. X‐ray diffraction analyses of the single crystals show that is cubic belonging to space group while and are isomorphous belonging to the orthorhombic space group . X‐ray powder diffraction results on the other derivatives indicate that they are all isostructural with the Sr analogue. The alkaline earth thiogallates are the basis of a new type of sulfide phosphor. Rare earth ions readily substitute for the alkaline earth in the host lattice resulting in phosphors that fluoresce strongly under ultraviolet and cathode rays. The luminescence properties of the host compounds and the Ce+3 and Eu+2‐Activated phosphors are described.

Effects of Interionic Coupling on the Electronic Spectra of Transition Metal Ions. The Ligand Field Spectra of CsNiCl3 and CsNiBr3

Abstract: The polarized crystal spectra of CsNiCl3, CsNiBr3, and nickel(II) doped into the isostructural magnesium salts, CsMgCl3 and CsMgBr3, have been investigated in the near infrared and visible region. The spectra can be satisfactorily interpreted using the Liehr and Ballhausen ligand field model for a d8 system in an octahedral environment. The intensities of the allowed, triplet→ triplet, transitions are essentially independent of nickel ion concentration and show the temperature dependence expected of a vibronic mechanism. On the other hand, the oscillator strengths of certain spin forbidden, triplet→ singlet, bands show a strong concentration dependence. These transitions are more intense in the spectra of the pure salts suggesting that their intensities are increased by exchange interactions between nickel ions. The intensity behavior of the multiplicity forbidden transitions in the nickel compounds is similar to that observed for a number of high spin manganese (II) salts.

Syntheses of Formato-, Acetato-, Benzoato-, and Chlorosubstituted Acetatoruthenium Complexes, and Their Properties

Abstract: Complexes with the general formula of [Ru2(RCOO)4X], where R=H, X=Cl, or Br; R=Me, X=Cl, Br, I, SCN, NO3, or MeCOO; R=ph, X=Cl, or Br, were prepared. The magnetic properties, conductivities, polarographic behavior, and infrared spectra of these complexes were investigated. All the complexes show magnetic moments of 2.84–2.96 B.M., and their susceptibilities, at from about 300 to 100°K, can be fitted to the Curie-Weiss law with negative values of the Weiss constant (θ=−30–−60°K). These complexes seem to be isostructural. Monochloroacetato-, and trichloroacetatoruthenium complexes ([Ru2(CH2ClCOO)4Cl]·2H2O and [Ru(OH)(CCl3COO)2(H2O)]) were also prepared.

The vibrational spectra and structures of rare earth oxides in the A modification

Abstract: Crystallographic studies of La2O3 and the oxides isostructural with it have failed to decide between noncentrosymmetric space group D32(P321) and the centrosymmetric space group D3d3(P3m1) for their structure. The infrared and Raman spectra of La2O3 and Nd2O3 have been obtained and the absence of coincidences between the spectra unequivocally favours the centrosymmetric space group. The vibrational spectra have been analysed using the Wilson FG matrix method and force constants for metal-oxygen and oxygen-oxygen interactions derived, assuming a quadratic central force field.

Comparison of Anomalies Observed in U‐ and Ce‐Intermetallics

Abstract: The temperature dependence of the electrical resistivity and the magnetic susceptibility has been investigated for the compounds UAl2, UAl3 and the isostructural compounds UX3 (X=Ga, In, Si, Ge, Sn), and finally for UAl4 and UGa2. The influence of a variable U concentration has been studied for the pseudobinary compounds U1−xYxAl2 and U1−xYxGa2. The results are discussed in terms of a localized‐spin‐fluctuations model. The differences and the similarities between the electrical properties of these U compounds and Ce compounds, such as CeAl2 and CeAl3, are briefly discussed.

Crystal structures of bis-(N-methyl-N-phenyldithiocarbamato)-nickel-(II) and -copper(II)

Abstract: The crystal and molecular structures of the title compounds have been determined by single-crystal X-ray diffraction methods, using conventional Patterson and Fourier heavy-atom methods, followed by block-diagonal least-squares refinement to R 0·116 (Ni) and 0·125 (Cu) for 1106 and 1202 visually estimated independent observed reflections. The compounds are isomorphous and isostructural with monoclinic unit cells, space group P21/a, containing two discrete molecules; [Ni(CS2·NMePh)2]: a= 19·30 ± 0·02, b= 6·592 ± 0·003, c= 7·658 ± 0·003 A, β= 107·8 ± 0·1°; [Cu(CS2·NMePh)2]: a= 19·40 ± 0·02, b= 6·612 ± 0·003, c= 7·701 ± 0·003 A, β= 107·5 ± 0·1°.The heavy atom in each structure occupies the special position (0,0,0), (½, ½,0) with symmetry and is necessarily planar co-ordinated by four neighbouring sulphur atoms at approximately equal distances: Ni–S 2·208(3) and 2·198(3)A, S(1)–Ni–S(2) 79·2(1)°; Cu–S 2·329(3) and 2·274(3)A, S(1)–Cu–S(2), 77·7(1)°. The remainder of the S2CNC2 ligand fragment is planar and conjugated, with normal geometry. There is evidence for hydrogensulphur intermolecular interactions. The plane of the phenyl ring lies at 82° to that of the conjugated ligand fragment in both cases, apparently as a result of steric interaction with the methyl group, and as a consequence of this both compounds are monomeric although it is usual for bis-(NN-dialkyldithiocarbamato)copper(II) derivatives to be dimeric in the solid state.

Crystal structure of platinum tetrachloride

Abstract: Platinum tetrachloride has been shown by X-ray powder methods to be isostructural with α-PtI4 and PtBr4.

Halogen nuclear quadrupole resonance and structural relationships in some complex halides of zinc and copper

Abstract: X-ray diffraction and halogen nuclear quadrupole resonance (n.q.r.) methods show that Rb3ZnBr5, (NH4)3ZnBr5, and CsZnI5 are isostructural with orthorhombic (NH4)3ZnCl5, and that Rb3ZnCl5 has the tetragonal Cs3CoCl5 structure. ZnI2,2NH3 is isomorphous with the corresponding chloride and bromide diammines. Rb2ZnBr4 and (NH4)2ZnBr4 have structures of Cs2ZnBr4 type, although the rubidium salt shows some stacking faults. In the complex chlorides 35Cl n.q.r. frequencies are grouped about 9 MHz, while the bromides have 81Br frequencies grouped around 60 MHz. The ½ → 3/2 transitions of 127I in the iodides are in the region of 76 MHz. The diammine compounds ZnBr2,2NH3 and ZnI2,2NH3 have frequencies close to the mean values for the ZnBr42- and ZnI42- ions respectively, but in the hydrates ZnCl2,l⅓H2O,ZnBr2,2H2O, β-KZnBr3,2H2O, and KZnI3,2H2O the halogen frequencies are increased. N.q.r. and X-ray data are also reported for the compound Cs3CuCl5, formed by quenching the melt. This compound slowly disproportionates at room temperature into Cs2CuCl4 and CsCl.

Low‐Temperature Magnetic Characteristics of Tetrahedral CoCl4 2−. II. Nature of the Phase Transition in [(C2H5)4N]2CoCl4

Abstract: Magnetic susceptibility measurements have been made between 1.5 and 20°K on [(C2H5)4N]2CoCl4. The results show that the CoCl4 2− tetrahedra are oriented such that their unique axes lie in or near the (001) plane while maintaining the tetragonal symmetry exhibited by the crystal at room temperature. Values for the parameters D and E have been obtained, as well as the principal g values. The results indicate that the CoCl4 2− anions in this compound behave similarly to those doped into the isostructural material [(C2H5)4N]2ZnCl4.

Low‐Temperature Magnetic Characteristics of Tetrahedral CoCl4 2−. I. g‐Tensor Orientation in Doped [(C2H5)4N]2ZnCl4

Abstract: Electron paramagnetic resonance measurements were made on single crystals of cobalt‐doped tetraethylammonium tetrachlorozincate (II) at 4.2°K. The results show that the CoCl4 2− tetrahedra are oriented in several magnetically nonequivalent directions in the host lattice, which is isostructural with the analogous cobalt compound, tetraethylammonium tetrachlorocobaltate (II). Each tetrahedron can be characterized by an effective spin S′= 12 and by the principal g values gx ′=5.44, gy ′=4.84, and gz ′=2.34. Although the individual CoCl4 2− anions exhibit only rhombic symmetry, these ions are so oriented at 4.2°K as to maintain the tetragonal axis exhibited by the crystal at room temperature.

19 F nuclear magnetic resonance spectra of fluoro-complexes of platinum and palladium

Abstract: 19 F N.m.r. spectra of [MF(PR3)3][BF4], M = Pd or Pt, unequivocally confirm the assigned structures and comparison of coupling parameters with those in isostructural hydrido-complexes suggests a very small s character for the platinum–fluorine bond.

Studies of vanadium(III) aqua chloro complexes and some related compounds

Abstract: Preparative and structural studies on several series of vanadium(111) aqua chloro complexes and related compounds are reported. Results indicate that all compounds contain vanadium(111) in pseudo-octahedral coordination. Evidence is presented from electronic, infrared, and nuclear quadrupole resonance spectra, X-ray powder diffraction, and magnetic data. The compounds of empirical formulae VX3,6H2O (X = Cl, Br), RbVCl4,6H2O, and Cs2VX5,nH2O (X = Cl, n = 4; X = Br,n = 5) are all shown to contain the green trans-[V(OH2)4X2]+ ion. For compounds of formula AI2VCl5,H2O (A = Cs, Rb, K, NH4) prior methods of preparation are reexamined and a new method of preparation is given. Physical studies confirm that these compounds contain the red complex ion [V(OH2)Cl5I2-. The salts comprise structures of two types, one for A = Cs, the other for A = K, NH4, Rb; the latter salts are isostructural with K2FeCl5,H2O. The anhydrous compounds A12VCl5 (A = Cs, Rb) are also examined and the preparation of the rubidium salt is reported for the first time. For these compounds the magnetic results are interpreted in terms of a weak antiferromagnetic interaction in a proposed polymeric structure and this is supported by other evidence. Some data are reported for VBr3 and VI3.

Disordered crystal structures of six complexes of the type, Me2XCR1R2·CF2XME2·M(CO)4(M = Mo or Cr; X = As or P; R1= F or H; and R2= H, CF3, or CL)

Abstract: Crystal structures of four compounds of the type Me2XCR1R2·CF2XMe2·M(CO)4(M = Mo or Cr; X = As or P; R1= F or H; and R2= H or Cl) have been determined, and two previously reported crystal structures of this type (R2= H or CF3) have been reinterpreted. Four compounds with R2= H are isostructural, space group Pbca, a ca. 18, b ca. 15, c ca. 13 A, Z= 8. Two compounds with R2= Cl and CF3 have structures which are quite similar to each other, the former having space group Pbca, a= 23·41, b= 12·59, c= 11·57 A, Z= 8, and the latter C2/c, a= 25·06, b= 13·27, c= 11·56 A, β= 102·8°, Z= 8. The structures were determined from diffractometer data by Patterson, electron-density, and full-matrix least-squares methods, the final R varying from 0·05–0·08 for 1200–1800 observed reflexions.The crystals all contain disordered arrangements of molecules with normal geometries and dimensions; each crystal has two molecular configurations distributed at each lattice site, the occupancy of the two orientations varying from 1 : 1 to ca. 6 : 1. The metal atoms are co-ordinated in slightly distorted octahedral arrangements to two arsenic or phosphorus atoms and to four carbonyl groups, the X–M–X angles being 82–85°. The Mo–As, Mo–P, and Cr–As bond lengths are 2·58, 2·48, and 2·43 A. The five-membered chelate rings have the usual puckered conformation, with one carbon atom displaced further (ca. 0·4 A) from the X, M, X plane than the other (ca. –0·25 A); the ligands thus have staggered conformations with X–C–C–X dihedral angles of ca. 50°. Intermolecular packing is governed by van der Waals inteactions, the most interesting feature being the disordered arrangements.

Studies of some thermally unstable complexes of group V trihalides with trimethylamine and [2H9]trimethylamine by infrared, Raman, and matrix-isolation Raman spectroscopy, normal co-ordinate analysis, and structural methods

Abstract: Low-temperature ir and Raman spectroscopy, ligand deuteriation, and matrix-isolation Raman techniques are used to determine the shapes of the thermally unstable complexes PCl3,NMe3 and PBr3, NMe3 Comparison of the observed and calculated vibrational spectra for the phosphine complexes with the similar data for AsCl3,NMe3(whose crystal structure is known) suggest that they are all isostructural and form pseudotrigonal bipyramidal molecular complexes having a stereochemically active lone pair of electrons in the equatorial plane, which can be considered to be replacing an equatorial chlorine atom in the isoelectronic Group IV complexes MX4, NMe3

Crystal and molecular structure of phenyl(triphenylsilyl)diazomethane

Abstract: Crystals of the title compound are orthorhombic, space group Pbca, a= 26·19(5), b= 9·17(2), c= 16·70(3)A, Z= 8. The molecule is monomeric, with an essentially linear C–N–N unit and planar CC(N2)Si skeleton. Principal bond lengths and angles are : N–N 1·130(16), N–C 1·280(17), mean Si–C 1·865, mean C–C(aromatic) 1·373, and C–C(exocyclic) 1·468(19)A; Si–C(N2)–C 125·7(8), Si–C–N 115·3(1·0), and C–C–N 118·8(1·2)°. The structure was determined from photographic data, and refined by full-matrix least-squares methods to R 0·117 for 1380 unique reflections. Unit-cell data for the germanium analogue show it to be isostructural.

Ueber metall-alkyl-verbindungen 13. mitt. darst. der alkali-tetramethylindate und kristallstrukturen von li(in(ch3)4) und na(in(ch3)4)

Abstract: The preparation and IR spectra of alkali tetramethylindates, M 1 [In(CH 3 ) 4 ] (M 1 = Li, Na, K, Rb, Cs), are reported. The structures of LiInMe 4 and NaInMe 4 have been determined from single-crystal X-ray intensities collected photographically. Both compounds are isostructural. They crystallize in cubic primitive lattices with one formula unit per unit cell [space group P 23 or P 4 3 m , cell dimension a = 5.394, 5.682 A resp.]. The compounds consist of regular tetrahedral InMe 4 anions and alkali cations. InC distances are 2.22, 2.20 A respectively. Each alkali cation is surrounded by the 4 nearest methyl groups in tetrahedral array. Crystal structures and IR data are in agreement with the assumption that tetramethylindate anions are isolated from alkali cations.