Crystal Structures and Properties of New Mixed-Ligand Complexes of Nickel(II) Diisobutyldithiophosphinate with Imidazole and 3,5-Dimethylpyrazole

The reaction of Ni{(i-C₄H₉)₂PS₂}₂ with imidazole and 3,5-dimethylpyrazole in ethanol gave paramagnetic (_ef = 3.02 and 3.11 BM) mixed-ligand complex compounds [Ni(Im)₂{(i-C₄H₉)₂PS₂}₂] (I) and [Ni(Pyr){(i-C₄H₉)₂PS₂}₂] (II). Single crystals were grown and the crystal structures of I and II were determined from X-ray diffraction data (CAD-4 diffractometer, Mo radiation, 1483 , R = 0.0344 for I and 2630 , R = 0.0486 for II). The crystals are monoclinic with cell dimensions a = 12.845(2), b = 10.250(1), c = 13.431(1) , = 115.89(1)°, V = 1591(1) ³, Z = 2, d _calc = 1.281 g/cm³, space group (for I); a = 11.152(3), b = 12.483(2), c = 23.389(4) , = 100.78(1)°, V = 3199(2) ³, Z = 4, d _calc = 1.191 g/cm³, space group (for II). The structures consist of discrete monomer molecules. The coordination polyhedron of the Ni atom is a compressed octahedron NiN₂S₄ (in I) and a tetragonal pyramid NiNS₄ (in II) formed by four S atoms of the two cyclic bidentate ligands i-Bu₂ and the N atoms of two monodentate ligands (Im molecules in trans-positions) or the N atom of the monodentate Pyr ligand in complexes I and II, respectively. The character of interaction between molecules I and II and molecular packing modes are considered. The electronic spectra of the complexes are consistent with the symmetry of chromophores found from X-ray data.     

New Data on the Crystal Structures of Colusites and Arsenosulvanites

The crystal structures of three minerals (arsenosulvanite, V,As-germanite, and colusite) of the general crystal chemical formula (As, Ge, Sn, Sb, V)₆S₃₂, where Cu^M, V^M are cations at interstitial positions, 0.2 x 2.0, 2.7 y 0, (space group , a = 10.527; 10.600; 10.653 ; R = 0.066; 0.046; 0.033) have been determined using single-crystal X-ray diffraction data. The minerals are the two structural modifications of the compound with the ideal formula V₂Cu₂₄As₆S₃₂; they differ from each other in the occupancy of the interstitial position 2a. In colusite, this position is occupied by the V⁵⁺ cations; in arsenosulvanite and V,As-germanite, by Cu²⁺. A characteristic feature of the structures is the presence of octahedral [ S₄]Cu₆ ( = V, Cu) complexes not directly interacting with each other and lying inside the Laves polyhedra. In the structures of arsenosulvanite and V,As-germanite, a sulvanite framework consisting of interpenetrating Laves polyhedra T₃S₄ ( = V, Cu; T = Cu, As, Ge) has been found. The sulvanite framework is statistically distributed over the sphalerite matrix. The variable composition of the minerals is due to heterovalent isomorphism in the sphalerite position 6c. Charge disbalance arising from substitution of the pentavalent arsenic cations by cations of lower valence is compensated by the appearance of additional Cu²⁺ cations. The nonstoichiometry of the compositions is explained by the presence of vacancies in the interstitial and sphalerite positions.     

On chemical bonding between molecular fragments. Closed-shell fragments

The chemical bonding between two closed-shell molecular fragments has been analyzed in terms of comparison of the antisymmetrized product of wave functions of the fragments with the wave function of a molecule composed of these fragments ^M . As a measure of the fragments' electronic structure variation upon molecule formation we took the cosine of the angles between ^M and in Hilbert space, as well as between the corresponding first-order density matrices ^M and . As an example, compounds of the type BH₃L (L=CO, NH₃, PH₃, H₂O, PF₃) have been considered. It is stressed that a necessary condition of chemical bonding between closed-shell fragments is the contribution of vacant orbitals of fragments into the bond.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 34, No. 3, pp. 3–8, May–June, 1993.Translated by L. Smolina     

Ionic Mobility, Structure, Phase Transition, and Conductivity in (NH4)3Sb4F15

Fluoride and ammonium ion dynamics in (NH₄)₃Sb₄F₁₅ was studied by ¹H and ¹⁹F NMR spectroscopy in the range 180-440 K. Types of ionic motion were determined, and their activation energies were estimated. The crystal structure of a single crystal of (NH₄)₃Sb₄F₁₅ (space group ) was solved. In the range K, a reversible phase transition has been found. Based on the experimental values of conductivity of (NH₄)₃Sb₄F₁₅ ( S/cm at T = 440 K), this antimony(III) fluoride is classified as a superionic conductor.     

Electronic Energy Structure of a Series of Chalcopyrite-Like Compounds AgGaS2–CdGa2S4–InPS4

The effect of pseudovacancies on the density of electronic states of valence electrons in AgGaS₂, CdGa₂S₄, and InPS₄ is studied both experimentally, by means of X-ray spectroscopy, and theoretically, by calculating the partial densities of electronic states using the local coherent potential. The compounds under study are the derivatives of the sphalerite structural type (doubled cell) with gradually increasing deficiency of metals from to and further to , where is a vacancy. The environment of the metal atoms remains tetrahedral, while that of the sulfur atoms changes with increasing number of vacancies from four (AgGaS₂) to three (CdGa₂S₄) and two (InPS₄). For the compounds under study, SK and PK X-ray emission and absorption spectra were recorded at a resolution of about 0.2 eV, and the local partial densities of states were calculated for all components of the compounds. The theoretical curves practically coincide in shape and energy position of fine structure elements with the corresponding experimental curves. This allowed reliable conclusions about the energy positions of electronic states at the top of the valence band and about the dependence of the SK emission and absorption spectra in the series of compounds under study on variation of the crystal structure and on the chemical composition of the nearest surroundings of sulfur atoms.     

Critical evaluation of the effective resonance energy concept and the epithermal neutron spectrum shape-factorα for reactor NAA purposes

The epithermal reactor neutron spectrum shape-factor, and the associated effective resonance energy for a given nuclide, are examined theoretically in great detail. First the necessity, meaning and importance of the choice of a reference neutron energy in a non-ideal spectrum (0) are explained. Next, the definition and practical calculation of are discussed, showing that the relation between the reasonance integrals in ideal and non-ideal spectra cannot be described adequately by two independent parameters and . The exact meaning of the logarithmic expression defining an independent of is clarified, its limits of validity are established as a function of and, as a result, it follows that relatively large systematic errors on can be introduced by its use. It is shown that is dominated by the first lowest resonance energies for a given nuclide, making its vulnerability to literature updates of resonance parameters almost equal to those of individual resonances. The effect, on the epithermal and total activation of specific nuclides, of large systematic and statistical errors on and, is calculated for a series of nuclides (different I₀/₀ and ) and irradiation facilities (different and _the), and represented graphically.Finally, the effect of important errors on and is calculated for final NAA results in terms of concentrations, botained by a comparator technique based on the¹⁹⁷Au reference nuclide. Conclusions are drawn concerning the impact of the foregoing on the usefulness of comparator type reactor NAA as an alternative to classical NAA using multi-element standards.     

Mixed-Ligand Complexes Zn(2,2′-Bipy)(ROCS2)2 with Mono- and Bidentate Ligands {\text{ROCS}}_{\text{2}}^ - (R = i-Pr, i-Bu)

The mixed-ligand complexes Zn(2, -Bipy)(i-PrOCS₂)₂ (I) and Zn(2, -Bipy)(i-BuOCS₂)₂ (II) were synthesized. Their structures were solved using the X-ray diffraction data (CAD-4 diffractometer, MoK radiation, 1873 and 1948 F _hkl , R = 0.0357 and 0.0338). The crystals are triclinic with unit cell dimensions a = 10.002(2), b = 11.080(2), c = 11.756(2) , = 78.46(3), = 75.49(3), = 63.50(3)°, V = 1122.9(4) ³, Z = 2, space group (for complex I) and a = 8.760(2), b = 12.520(3), c = 13.252(3) , = 63.93(3), = 71.10(3), = 88.01(3)°, V = 1225.2(5) ³, Z = 2, space group (for II). The structures are based on discrete monomeric molecules. The polyhedra of Zn atoms are tetragonal pyramids (ZnN₂S₃, c.n. 4+1, both bidentate and monodentate ligands coordinated to the Zn atom). The packing of molecules and the character of their interaction in the structures are considered.     

Cluster Models of Co2+ at the Cation Sites of Zeolite ZSM-5

The local structure of Co₂₊ at the -, , and -cation sites of zeolite ZSM-5 was calculated in terms of density functional theory using the cluster approach. The local geometry of the oxygen environment of Co₂₊ is characterized; it is found that the ion stabilization energy increases in the series .     

Synthesis and Crystal Structure Investigation of Trinitrotriamminerhodium(III) [Rh(NO2)3(NH3)3]

Synthesis of the complex [Rh(NO₂)₃(NH₃)₃] is described. The compound crystallizes as monoclinic colorless plates. Crystal data: a = 7.176(10), b = 10.407(2), c = 10.989(2) , = 93.27°, V = 819.3(2) ³, space group , Z = 4, d _calc = 2.367 g/cm³. The structure is molecular and built of neutral complexes having cis-facial configuration. The unit cell of the crystal contains two independent complexes.     

Crystal Structure of the Mixed-Ligand Compound [HgPhen{(C2H5)2NCS2}2] and the Character of Intermolecular Interactions in [MPhen{(C2H5)2NCS2}2] (M = Zn, Cd, Hg)

Single crystals of the mixed-ligand complex compound [HgPhen(Et₂NCS₂)₂] were obtained. The crystal structure of the compound was determined by X-ray diffraction analysis (CAD-4 diffractometer, Mo radiation, 3640 F _hkl , R = 0.0280). Triclinic crystals with cell parameters a = 10.308(2), b = 11.171(3), c = 11.552(2) , = 94.16(2), = 96.66(1), = 105.17(2)°, V = 1267.8(5) ³, Z = 2, d _calc = 1.774 g/cm³, space group . The structure is composed of discrete monomer molecules. The coordination polyhedron of the Hg atom is a distorted octahedron formed by four S atoms of the two cyclic bidentate Et₂ ligands and two N atoms of the cyclic bidentate Phen ligand. The character of interactions between [MPhen(Et₂NCS₂)₂] (M = Zn, Cd, Hg) molecules and their packing in the structure are considered.     

Untersuchungen über die diamagnetische Suszeptibilität einiger Organo (imino-oxy)silane

Diamagnetic susceptibilities of trimethyl(imino-oxy)silanes,Me ₃SiON CMeR, and dimethyldi(imino-oxy)silanes,Me ₂Si(ON CMeR)₂, containing Si–O bonds are reported. _M of these silicon compounds has been calculated theoretically from the method ofBaudet et al. and a good agreement has been obtained between the observed _M values and the corresponding calculated values. _Si in these compounds has been calculated graphically and the lower values have been explained on the basis of back-bonding to the silicon atom from the oxygen lone pair.     

Thermodynamics of NaCl in Aqueous Ethylene Glycol, Acetonitrile, and 1,4-Dioxane Mixtures from Emf Measurements at 25°C

The electromotive force of the amalgam cell {Na_xHg_1-xNaCl(m)AgClAg} has been measured at 25°C as a function of the mole fraction x of Na in amalgams and of the molality m of NaCl in (ethylene glycol + water), (acetonitrile + water), and (1,4-dioxane + water) mixed solvents, containing up to 0.8 mass fraction of the organic component, with relative permittivities 27. The relevant standard molal electromotive forces have been determined, together with the mean molal activity coefficient _± of NaCl as a function of its molality. In the case of (ethylene glycol + water) mixtures, a linear dependence of on the mass fraction of ethylene glycol is observed, which is quite unusual, The Debye-Hückel equation is applicable successfully over the whole range of molalities explored, which extends to the vicinity of the solubility limit of NaCl in each solvent. The dependence of the standard emf on the logarithm of the volume fraction of water in the aqueous-organic solvent mixtures have been analyzed in terms of Feakins and French's theory, leading to a primary hydration number 7.2 for NaCl, in good agreement with previous results employing different methods.     

Thermal decomposition of crystalline molecular sieve (C3H7)3N-AlPO4-5

The thermal decomposition of (C₃H₇)₃N-AlPO₄-5 in inert and oxidizing gas atmospheres has been studied by TG, DTG and DTA in the temperature range 303–1273 K. The removal of tripropylamine occluded in the channels of the aluminophosphate occurs in a number of steps and is strongly influenced by the gas atmosphere.

---

Zusammenfassung Die thermische Zersetzung von (C₃H₇)₃N-AlPO₄-5 wurde in inerter und oxydierender Gasatmosphäre mittels TG, DTG und DTA im Temperaturbereich von 303–1273 K untersucht. Der Austritt des in den Kanälen des Aluminiumphosphats okkludierten Tripropylamins erfolgt über eine Anzahl von Stufen und wird stark von der Gasatmosphäre beeinflußt.

---

, (C₃H₇)₃N-AlPO₄-5 303–1273 . , , .

---

---

We are grateful to Dr. V. G. Gunjikar, Mr. J. S. Gujaral and Dr. (Mrs) A. Mitra of the Special Instrument Group of our Laboratory for their co-operation in the work.     

Unusual Reaction of 1,1,1-Trimethyl(allyldifluoro)disiloxane with Hexamethyldisiloxane

The reaction of 1,1,1-trimethyl(allyldifluoro)disiloxane with hexamethyldisiloxane gives rise to previously unknown ,-bis(trimethylsiloxy)oligoallylfluorosiloxanes Me₃SiO(FRSiO) _n SiMe₃ (n = 1-3) and -(trimethylsiloxy)--allyldifluorosiloxyoligoallylfluorosiloxanes Me₃SiO(FRSiO) _m SiRF₂ (m = 1 and 2), where R = CH₂ = CHCH₂.     

Crystal Structure of Diaqua(2.2.2-cryptand)strontium Bis(thiocyanate)

The crystal structure of the title compound, [Sr(C₁₈H₃₆N₂O₈)(H₂O)₂]²⁺·2SCN^– (I), was investigated by X-ray diffractometry: space group , a = 10.724(3), b = 15.512(3), c = 16.826(4) , = 97.96(3)°, Z = 4. The structure was solved by direct methods. The full-matrix least-squares anisotropic refinement converged to R = 0.038 for all 3837 independent measured reflections (CAD-4 automatic diffractometer, ). In the structure of I, the Sr²⁺ cation (c.n. 10) lies in the cavity of the cryptand ligand and is coordinated by all of its eight heteroatoms (6O+2N) and two O atoms of the two water molecules; its coordination polyhedron is a distorted two-base-centered bicapped trigonal prism. The cryptand ligand in I has an asymmetric conformation. The crystal structure of I has interionic hydrogen bonds (formed by the H atoms of the ligand water molecules) linking the complex cations and the SCN^– anions into complex infinite chains.     

An alternative way to analyze quasi-elastic light scattering data for broadly distributed samples

In Quasi-Elastic Light Scattering (QELS), an apparent average hydrodynamic radius can be calculated from the measuredz-average translational diffusion coefficient D _z by using the Stokes-Einstein equation: withk _B,T and being the Boltzmann constant, the absolute temperature and the solvent viscosity, respectively. It is known thatR _{h, app} is not the same as R _{h z} because , especially when a sample is broadly distributed. In order to obtain R _{h z} instead ofR _{h, app}, an alternative way to analyze QELS data is proposed: at first, we manipulate the measured correlation functionb ^1/2|g ⁽¹⁾(t)| into a new function ; and then, we can analyze this new function to obtain an apparent parameter D_app and an apparent distribution width . We have shown that no matter how broadly a sample is distributed, D_app can be easily reduced to R _{h z} , and is directly related to the distribution width. In this report, besides using a simulated time correlation function, we also used two measured correlation functions of a latex dispersion with a broad particle size distibution and a polystyrene standard with a broad molecular weight distribution to demonstrate this alternative way.     

Chemical algebra. V:G-weighted distance extensions and metrics

The first formulation of the definition equation of completely-G-invariant distance extensions from the action of a compact group G onto a metric space (E, d) is reminded. A more general equation ( ) is then consistently associated to a group G mapped by a numerical functionm and acting on a metric space (E, d) mapped by another continuous numerical function. A solution of ( ) is called a G-weighted distance extension ofd. A differential form of the equation is derived in order to provide a definition of a G-weighted metricds ² = (d/)² from a non-uniform map of an Euclidean space: = #G whenG is a finite group, butds ² is also defined by continuity whenG is an infinite compact group ( = oo).     

Formation of a Dimer with a Double Hydroxo Bridge in Nitric Acid Solutions of the Nitrosotetranitrohydroxo Complex of Ruthenium(II). Crystal Structure of K2[RuNO(NO2)3(μ-OH)]2

Fine yellowish orange crystals of the binuclear complex K₂[RuNO(NO₂)₃(-OH)]₂ were obtained by the reaction of K₂[RuNO(NO₂)₄OH] with a stoichiometric amount of 0.8 M nitric acid at room temperature. The compound was investigated by IR spectroscopy, X-ray phase analysis (DRON-3M, CuK radiation), and X-ray diffraction analysis (Nonius CAD-4, MoK radiation, graphite monochromator, scan mode, 1406 reflections). The crystals are poorly soluble in water and practically insoluble in ethanol and acetone; the compound is stable when stored in air. Crystal data for H₂K₂N₈O₁₆Ru₂ are: a = 8.596(2), b = 10.111(1), c = 9.537(1) , = 104.42(1)°, V = 802.8(2) ³, space group , Z = 2, _calc = 2.691 g/cm³. The structure is built of [RuNO(NO₂)₃(- complex anions and K⁺ cations.     

Thermodynamic characteristics of the system NaNO<Subscript>2</Subscript>-NaNO<Subscript>3</Subscript>

The activities and activity coefficients of the components of the system NaNO₂-NaNO₃, obtained from experimental saturated vapor pressures measured at 798, 823, and 848 K, were used to calculate the total and excess partial molar Gibbs energies , , entropies , , and total relative and excess thermodynamic properties G, G ^ex, S, S ^ex of the system.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 10, 2004, pp. 1747–1749.Original Russian Text Copyright © 2004 by Glazov, Dukhanin, Dkhaibe, Losev.     

Nitrogen Trichloride Decomposition in the Presence of Molecular Hydrogen: I. Promotion of Nitrogen Trichloride Decomposition by Molecular Hydrogen Additives Near the Lower Self-Ignition Limit

The promotion of the branched-chain decomposition of nitrogen trichloride by molecular hydrogen additives at room temperature and 20 torr manifests itself in a decrease in the induction period and the acceleration of reactant consumption with an increase in the hydrogen concentration in the NCl₃+ H₂+ He mixtures. The emission spectrum of the H₂+ NCl₃flame contains the intense bands of NCl (b ¹⁺– X ^3–, = 1 – 0, = 0 – 1, and = 0 – 0, where is the vibrational quantum number) and the bands of a hydrogen-free compound. The latter bands can be assigned to electronically excited NCl ₂radicals formed in the H + NCl₃reaction. The calculations restrict the number of elementary reactions favoring promotion. The promotion effect in the system studied should be due to the side reaction of linear branching. The occurrence of the H + NCl₃reaction via two pathways (NHCl + 2Cl and NCl ₂+ HCl) ensures the qualitative agreement between the experimental data and calculation.