Crystal structure of Na3PO4 · 12H2O

The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is $\text{C2}\text{c}$ and a unit cell contains eight formula units. The unit cell dimensions of $\text{Na}{}_3\text{PO}{}_4\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO₆ octahedra. The hydrogen bonding scheme is given.     

The structure of a barium niobium silicon oxide with the probable composition Ba6+xNb14Si4O47 (x ⋍ 0.23)

Reaction of BaO, Nb₂O₅, and Nb in mole ratios of 2.4:1.6:1 in an evacuated silica capsule at 1250°C produces a mixture of at least two products, one of which has the probable composition $\text{Ba}{}_{\mathrm{6+x}}\text{Nb}{}_{14}\text{Si}{}_4\text{O}{}_{47}\text{(x ? 0.23)}$. This compound has an hexagonal unit cell of dimensions a = 9,034 ± 0.004 Å, c = 27.81 ± 0.02 Å, probable space group $\text{P6}{}_3\text{mcm}\text{, Z = 2}$. Its structure has been determined from 942 independent reflections collected by a counter technique and refined by least squares methods to a conventional R value of 0.062. The basic structure consists of strings of four NbO₆ octahedra sharing opposite corners, each string joined to the next by edge sharing of the end octahedra, so that the c axis corresponds to the length of a strand of seven corner-linked octahedra. Chains of three such strands are formed by corner sharing between the strands. The chains in turn are joined by NbO₆ octahedra and Si₂O₇ groups in which the SiOSi linkage is linear. Barium atoms are in sites between the chains coordinated by 13 oxygen atoms. A second site, 15 coordinated, probably has a small amount of barium as well; the fractional occupancy for barium in this site is 0.076.     

Metallierungsreaktionen an cyclometallierten komplexen des typs Mo-C6H4CH2PR2)2(M = Pd,Pt)

The complexes of type $\text{M}\text{o}\text{-C}{}_6\text{H}{}_4\text{CH}{}_2\text{P}$R₂)₂ (M = Pd, Pt) are readily deprotonated by n-Buli under various conditions yielding μ-C-bis-dilithiated species. The resulting carbanions are attacked by the electrophiles Mel, Me₃SiCl and Ph₂PCl to form the corresponding disubstituted derivatives. The reaction with AuCl . PPh₃ yields heterobimetallic complexes with two different MC σ-bonds. The compounds obtained are analytically and spectroscopically characterized.     

A kinetic study of the system γ-AlOOHAl2O3

A time-temperature study has been made of the system: $\text{γ-}\text{AlOOH (boehmite)}\text{Al}{}_2\text{O}{}_3$. The isothermal TTT diagram produced demonstrates the course of the transformation sequence, which involves a number of metastable transition alumina intermediate phases. This type of treatment allows calculation of kinetic parameters for the various transformation processes, and these may be correlated with the mechanisms operating. Kinetic aspects of variations in microstructure and crystal structure have also been studied. In particular, the progress of cation migration processes involved in the transformation γ → δ-Al₂O₃ has been followed in terms of the continuous variation of the spinel subcell parameters.     

A new tungsten trioxide hydrate, WO3 · 13H2O: Preparation,characterization, and crystallographic study

A new hydrate of tungsten trioxide, $\text{WO}{}_3\text{·}\text{1}\text{3}\text{H}{}_2\text{O}$ has been obtained by hydrothermal treatment at 120°C of an aqueous suspension of either tungstic acid gel or crystallized dihydrate. This hydrate has been characterized by different methods. A crystallographic study was carried out from X-ray powder diffraction. The hydrate crystallizes in the orthorhombic system: a = 7.359(3) Å, b = 12.513(6) Å, c = 7.704(5) Å, Z = 12. The existence of structural relationships between the hydrate, $\text{WO}{}_3\text{·}\text{1}\text{3}\text{H}{}_2\text{O}$, and the product of dehydration, hexagonal WO₃, has permitted us to propose a structural model in agreement with the experimental data. $\text{WO}{}_3\text{·}\text{1}\text{3}\text{H}{}_2\text{O}$ must be regarded as an interesting compound because its dehydration leads to a new anhydrous tungsten trioxide, hexagonal WO₃.     

Unusual route to and rearrangement of four-membered ring complexes C5H5Fe (CO) [ (C6H5)2PN(R)CH (C6H5) ]

The amine substituted phosphines (C₆H₅)₂PN(H)CH₂CH₃ and (C₆H₅)₂PN(H)CH₂C₆H₅ react with C₅H₅Fe(CO)₂CH(C₆H₅) (OCH₃) photolytically to give moderate yields of the four-membered chelate ring complexes C₅H₅$\text{Fe (CO) [(C}{}_6\text{H}{}_5\text{)}{}_2\text{PN (CH}{}_2\text{CH}{}_3\text{) C}$H (C₆H₅)] and C₅H₅$\text{Fe (CO) [(C}{}_6\text{H}{}_5\text{)}{}_2\text{PN (CH}{}_2\text{C}{}_6\text{H}{}_5\text{)C}$H(C₆H₅)], respectively. Photolysis of C₅H₅Fe(CO)₂CH(C₆H₅) (OCH₃) in the presence of (S)-(?)-diphenyl(1-phenylethylamino)phosphine leads to the isolation of C₅H₅Fe(CO)[(C₆H₅)2PNC(CH₃) (C₆H₅)]CH₂C₆H₅ which is proposed to arise from a formally 1,3-hydrogen shift rearrangement of an intermediate four-membered chelate ring complex.     

A study of the spinel materials LiTi2O4 and Li43Ti53O4 by photoelectron spectroscopy

HeI-excited valence-band ultraviolet photoelectron spectra and MgKα-excited Ti-2p X-ray photoelectron spectra are reported for the spinel materials LiTi₂O₄ and $\text{Li}{}_{\mathrm{<mtext>4</mtext><mtext>3</mtext>}}\text{Ti}{}_{\mathrm{<mtext>5</mtext><mtext>3</mtext>}}\text{O}{}_4$. The presence of a Fermi edge in the ultraviolet photoelectron spectrum of LiTi₂O₄ confirms the metallic nature of this material, although the measured density of states at the Fermi energy is much lower than that expected from an independent-electron interpretation of the magnetic susceptibility. This difference is attributed to a strong interaction of the conduction electrons with the lattice vibrations. The localization of conduction electrons that occurs in the final state in the Ti-2p X-ray photoelectron spectrum of LiTi₂O₄ is attributed to a Coulomb interaction with a core hole.     

Darstellung ylidischer metallacyclopropankomplexe durch ringverkleinerung metallacyclischer vinylketonkomplexe. Molekülstruktur von C5H5W(CO)2[(PMe3)HC-CH(COMe)]

The addition of trimethylphosphane to five-membered metallacyclic vinylketone complexes of the type Ar$\text{M(CO)}{}_2\text{(HCCHCO}$R) (I) (Ar = η⁵-aromatic ring system: C₅H₅, C₅H₄Me, C₅Me₅; R = Me, Et, n-Bu; M = Mo, W) in pentane solution results in the formation of the ylidic metallacyclopropane complexes Ar$\text{M(CO)}{}_2\text{[(PMe}{}_3\text{)-HCC}$H(COR)] (II). In these 1:1 adducts the three-membered ring is stabilized by an electron-donating phosphonium and an electron-attracting acyl substituent. The negative charge in the ylidic complexes II is localized on the central metal providing it with Lewis base properties. An extraordinary high electron density can be observed on the metal of the derivative C₅H₅$\text{W(CO)(PMe}{}_3\text{)[(PMe}{}_3\text{)HCC}$H-(COMe)] (III) which is formed by a 1:2 addition of C₅H₅W(CO)(C₂H₂)-(COMe) and PMe₃. The metallacyclopropane complexes II and III are characterized by IR, ¹H NMR, ¹³C NMR, ³¹P NMR and mass spectroscopy. For C₅H₅$\text{W(CO)}{}_2\text{[(PMe}{}_3\text{)HCC}$H(COMe)], the results of an X-ray structure determination are presented.     

Oxygen defect K2NiF4-type oxides: The compounds La2−xSrxCuO4−x2+δ

Oxygen defect K₂NiF₄-type oxides $\text{La}{}_{\mathrm{2?x}}\text{Sr}{}_{\mathrm{x}}\text{CuO}{}_{\mathrm{<mtext>4?</mtext><mtext>x</mtext><mtext>2</mtext><mtext>+\delta </mtext>}}$ have been synthesized for a wide composition range: 0 ≤ x ≤ 1.34. From the X-ray and electron diffraction study three domains have been characterized: orthorhombic compounds with La₂CuO₄ structure for 0 ≤ x < 0.10, tetragonal oxides similar to LaSrCuO₄ for 0.10 ≤ x < 1 and several superstructures derived from the tetragonal cell ( with n = 3, 4, 4.5, 5, 6) for 1 ≤ x ≤ 1.34. The compounds corresponding to 0 < x < 1 differ from the other oxides in that they are characterized by the presence of copper with two oxidation states: + 2 and + 3. A model structure for La_0.8Sr_1.2CuλO_3.4, in which copper has only the + 2 oxidation state, and for which the actual cell is tegragonal—a = 18.80₄ Å and c = 12.94 Å—has been established. The particular structural evolution of these compounds is discussed in terms of a competition between the capability of Cu(II) to be oxidized to Cu(III) and the ordering of oxygen vacancies.     

The crystal structure of a new nonstoichiometric phase Cs1−xLu3F10−x (x ⋍ 0.25)

A high-temperature phase with the formula $\text{Cs}{}_{\mathrm{1?x}}\text{Lu}{}_3\text{F}{}_{\mathrm{10?x}}\text{(x ? 0.25)}$ has been characterized during the investigation of the CsFLuF₃ system. This phase crystallizes in the monoclinic system with unit-cell dimensions a = 13.764(5) Å, b = 7.947(1) Å, c = 4.299(2)Å, β = 90.04(5)° and space group Cm (No. 8), Z = 2. The structure was solved by conventional Patterson and Fourier methods and refined by full-matrix least-squares techniques to a conventional R of 0.053 (R_w = 0.079) for 2038 independent reflections recorded on an automatic four-circle diffractometer. The structure may be regarded as built up of (Lu₃F₁₀)^? layers that may be described as corner- and edge-shared LuF₇ pentagonal bipyramids. These layers run parallel to the (001) plane. The structure extends along the third direction by cornersharing involving axial vertices of the pentagonal bipyramids. This three-dimensional framework delimits tunnels running parallel to the c direction where the Cs⁺ ions lie. The partial occupancies of both the Cs site and one out of the seven independent fluorine sites results in the nonstoichiometry.     

Synthese et structure cristalline d'un nouvel oxyde mixte “FeV3O8” (FexV1−xO2; x ⋍ 0.25)

Single crystals of a new oxide “FeV₃O₈” ($\text{Fe}{}_{\mathrm{x}}\text{V}{}_{\mathrm{1?x}}\text{O}{}_2\text{: x ? 0.25}$) have been synthesized by slowly cooling a melted mixture with the composition, 8VO₂, 3V₂O₅, Fe₂O₃. The chemical formula has been determined by electron microprobe analysis. The compound, isostructural with AlNbO₄ and VO₂(B), has a monoclinic symmetry, space group $\text{C2}\text{m}$; the unit cell dimensions are a = 12.13Å, b = 3.679 Å, c = 6.547 Å, β = 106.85°. A structural refinement based on single crystal data has been carried out. It gave an R-factor of 1.9%. This refinement indicated that the iron and vanadium cations are partially ordered, although the average cation-oxygen distances for the two six-coordinated cations were exactly the same (1.961 Å). This conjecture was supported by the calculation of the cation valences.     

Studies of spinels. VII. Order-disorder transition in the inverse germanate spinels Zn2−x(Co,Ni)xGeO4(x ⋍ 1)

A series of germanate spinels Zn_2?x(Ni, Co)_xGeO₄ has been synthesized and investigated by X-ray diffractometry and infrared spectroscopy. Synthesis at 1200°C leads to cubic phases characterized by an inverse, disordered distribution of Ge and bivalent cations (essentially Ni or Co) over the octahedral sites; however, the presence of some short-range order is suggested by the infrared spectrum. Tempering at an appropriate temperature (between 800 and 900°C, depending on the $\text{Co}\text{Ni}$ ratio) leads to tetragonal spinel phases, corresponding to the 1:1 order between Ge and bivalent cation on octahedral sites. The transformation is sluggish and proceeds at a significant rate only in a narrow temperature range, just below the transition temperature. A comparison with the behavior of known inverse, ordered titanate spinels shows that, within the family of inverse II–IV spinels M₂^IIM^IVO₄, the ratio of the octahedral cationic radii is one of the factors determining the order-disorder transition temperature, and the importance of the tetragonal distortion.     

Structural intergrowth in the CaxLa1−xFeO3−x2 system (0 ≤ x ≤ 1): An electron microscopy study

An electron microscopy and diffraction study of several samples of the system $\text{Ca}{}_{\mathrm{x}}\text{La}{}_{\mathrm{1?x}}\text{FeO}{}_{\mathrm{<mtext>3?</mtext><mtext>x</mtext><mtext>2</mtext>}}$ shows these solids to be formed by the disordered intergrowth of two out of three of the ordered terms corresponding to $\text{x = 0, x =}\text{2}\text{3}$, and x = 1 (i.e., LaFeO₃, Ca₂LaFe₃O₈, and Ca₂Fe₂O₅). The relative amounts of the intergrowing individuals vary with x and may extend down to unit cell thickness; i.e., to the level of isolated extended defects.     

Wide-band proton NMR study of a new hydrate WO3 · 13H2O in the powder form

The proton NMR of a new hydrate $\text{WO}{}_3\text{·}\text{1}\text{3}\text{H}{}_2\text{O}$ as a powder was studied between ?140 and 100°C. The lattice can be considered as “rigid” at temperatures below ?80°C. The structural water corresponding to the above formula is coordinated in the form of water molecules. Above ?80°C it undergoes thermally activated hindered rotation. The compound also retains adsorbed surface “water,” partly in the form of strongly bonded OH groups, partly in the form of water molecules. Degassing at 175°C and 10^?4 Torr removes the adsorbed molecular water but leaves OH groups bonded to the surface.     

Diatomics-in-molecules potential energy surfaces for the collision-induced dissociation of excited Li2(1Πu) by helium atoms

The 1 ¹A″, 2 ¹A″, 3 ¹A′, 4 ¹A′, and 5 ¹A′ potential energy surfaces (PES) relevant to the collision-induced dissociation (CID) process $\text{Li}{}_2\text{(}{}^1\text{Π}{}_{\mathrm{u}}\text{) +}\text{He}\text{(}{}^1\text{S}{}_{\mathrm{g}}\text{) →}\text{Li}\text{(}{}^2\text{S}{}_{\mathrm{g}}\text{) +}\text{Li}\text{(}{}^2\text{P}{}_{\mathrm{u}}\text{) +}\text{He}\text{(}{}^1\text{S}{}_{\mathrm{g}}\text{)}$ are approximated by three diatomics-in-molecules models differing from each other in the source of diatomic input. The semi-empirical model, the most realistic of the three, shows the CID to depend critically on the position of avoided crossings on the PES and on the magnitude of the non-adiabatic coupling, which is estimated numerically. The ¹A″ calculations support a qualitative two-step mechanism recently proposed by Poppe and Whitton. The ¹A′ surfaces exhibit a degree of complexity which precludes a simple picture of the CID process. The results suggest that only a quantum scattering treatment or perhaps a very detailed surface-hopping trajectory calculation will be adequate for the interpretation of the experimental observations on this reaction, and the estimation of the cross sections.     

Das System TlClPbCl2

A reinvestigation of the x-T diagram was performed using DTA and X-ray techniques. Four compounds exist in the sytem of $\text{TlCl}\text{PbCl}{}_2$. The transformations of Tl₃PbCl₅ and TlPb₂Cl₅ are discussed. The compound Tl₂PbCl₄ exists only within a temperature interval of about 20°C. A compound of the formula Tl₇Pb₃Cl₁₃ is reported for the first time. Crystallographic data of TlPb₂Cl₅, high and low Tl₃PbCl₅, and Tl₇Pb₃Cl₁₃ are presented.     

Garnet-perovskite transformations in the Sm2O3Ga2O3 and Gd2O3Ga2O3 systems

The effect of heating garnet melts to various temperatures has been investigated. The previously reported decomposition of the garnet phase due to loss of Ga₂O₃ was corroborated. However, it was also observed that when gallium oxide loss is prevented and the maximum temperature of the melt exceeds a critical value, phase separation of garnet to perovskite and β-gallium oxide occurs:

$\text{RE}{}_3\text{Ga}{}_5\text{O}{}_{12}\text{?3RE}\text{GaO}{}_3\text{+}\text{Ga}{}_2\text{O}{}_3$

.The reverse reaction will occur by reheating the two-phase mixture to the garnet melting point.     

The crystal structure of Cs[VOF3] · 12H2O

The crystal structure of $\text{Cs[VOF}{}_3\text{]}\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ has been determined and refined on the basis of three-dimensional X-ray diffractometer data (MoKα radiation). The structure is monoclinic, a = 7.710(2), b = 19.474(7), c = 7.216(2)Å, β = 116.75(1)°, V = 967.5ų, Z =8, space group Cc (No. 9). The final R and R_w were 0.0295 and 0.0300, respectively, for 1356 independent reflections and 117 variables.The structure contains two crystallographically different VOF₅ octahedra linked so as to form complex chains. Two non-equivalent octahedra share one FF edge, forming V₂O₂F₈ doublets. Two F atoms, connected to different V atoms within the doublet, form an edge in the adjacent equivalent V₂O₂F₈ unit thus continuing the chain. The VO distances are 1.583(7) and 1.595(7) Å. The VF distances are in the range 1.881-2.205 Å, mean value: 1.989 Å. The H₂O group is a crystal water molecule.     

Thermodynamics of hydrogen trapping in intermetallic compounds: Application to LaNi5H

It has been observed for several intermetallic compound/H systems that deviations from Sieverts' law of ideal solubility occur which are in the opposite direction from the deviations from ideality which occur in pure metal/H systems. The principal source of nonideality on both types of interstitial solutions arises from the changes of the relative partial molar enthalpy of H₂ solution, ΔH_H, with H content. The variations of ΔH_H with H content are, however, in the opposite directions for intermetallic/H and pure metal/H interstitial solutions. Relative partial molar entropies for solution of H₂ in the α-phase of the $\text{LaNi}{}_5\text{H}$ system are given at 298.2 K. These have been determined from calorimetric determinations of ΔH_H and measurements of . The partial entropies show unusual extrema as a function of H content. A model based on trapping of H atoms is proposed which explains the variations of ΔH_H and ΔS_H. Since the deviations from ideality arising from an increase of ΔH_H with H content seem to be limited to solids with at least two different ordered metal components, e.g., intermetallic compounds, it seems reasonable to assign the trapping sites to interstices which result from an interchange of metal atoms. This interchange may create interstices rich in those nearest-neighbor metal atoms which have the greatest affinity for H.     

Carbonyl complexes of manganese(I) with chelating phosphino-alkyl or -acyl ligands. Crystal and molecular structure of [Ph2PCH2CH2(O)CMn(CO)2(dppm)l

The phosphine Ph₂PCH₂CH₂Cl reacts with fac-[XMn(CO)₃(dppm)] (X = Cl or Br) in refluxing toluene to give the complexes cis,cis-[XMn(CO)₂(dppm)(Ph₂PCH₂CH₂Cl)] (I). Treatment of those species with Na amalgam in THF leads to the alkyl complex [Ph₂$\text{PCH}{}_2\text{CH}{}_2\text{M}$n(CO)₂(dppm)] (II), which does not react with CO under normal conditions but can be converted into cis,cis-[ClMn(CO)₂(dppm)(PPh₂Et)] by reacting with HCl (g) in ether. If the reduction of I with Na/Hg is carried out in the presence of CO the compound cis-[Ph₂$\text{PCH}{}_2\text{CH}{}_2\text{(O)CM}$n(CO)₂(dppm)] (III) is obtained. The latter has also been prepared directly from fac-[BrMn(CO)3(dppm)], Ph₂PCH₂CH₂Cl, and Na/Hg in THF, and characterized by X-ray crystallography. The crystals are monoclinic, space group P2₁/n; refinement gave R = 0.053 for 2593 reflections with I ? 2.5σ(I). The reaction of the complex fac-[O₃ClOMn(CO)₃(dppm)] with Ph₂PCH₂CH₂Cl in Cl₂CH₂ gives the salt fac-[Mn(CO)₃(dppm)(Ph₂PCH₂CH₂Cl)]ClO₄ which isomerizes to mer-[Mn(CO)₃(dppm)(Ph₂PCH₂CH₂Cl)]ClO₄ in boiling butanol. Both cationic carbonyl complexes give the acyl species III upon reduction with Na amalgam.