Synthesis of perfluorochemicals for use as blood substitutes,Part I. Electrochemical fluorination of N-methyldecahydroquinoline and N-methyldecahydroisoquinoline

Electrochemical fluorination of N-methyldecahydroquinoline afforded mainly a mixture of $\text{cis}$ and $\text{trans}$ N-(F-methyl)-F-decahydroquinoline, their rearranged isomers and F-propyl-F-cyclohexane arising from the cleavage at carbon-nitrogen bonds, in a ratio of approximately 2:4:6:3. N-Methyldecahydroisoquinoline was also fluorinated electrochemically to give a mixture of $\text{cis}$ and $\text{trans}$ N-(F-methyl)-F-decahydroisoquinoline, their rearranged isomers and 1-(F-ethyl)-2-(F-methyl)-F-cyclohexane in a ratio of approximately 4:4:6:1. No correlation was found between the $\text{cis}$ and $\text{trans}$ ratio of starting materials and that of the corresponding perfluorinated amines. Fluorination of N-methyl-1,2,3,4-tetrahydroquinoline gave much lower yields.     

Further studies of the formation of mercury barbiturate films at a mercury anode

Potential sweep and step experiments have been used to reinvestigate the electrochemistry of 5,5′-disubstituted barbituric acids at a mercury electrode and it is confirmed that while all such compounds form a monolayer of an insoluble mercury barbiturate, the mechanism and kinetics of these oxidations depend on the detailed structure of the barbiturates. The experiments have been extended to barbituric acid and 5-ethylbarbituric acid and these would suggest that when the barbiturate is not fully substituted in the 5-position, more than a monolayer of the mercury salt is formed.     

Dynamics and structure of some tricarbonylferrole-iron tricarbonyl derivatives

A series of compounds of the formula Fe₂(CO)_6-x(PR₃)_x(R′C₂R″)₂ (x = 0, R′ and R″ = Ph, R′ and R″ = H, R′ = Ph and R″ = H; x = 1, K = Ph or n-Bu, and R′ and R″ = Ph) were studied by ¹³C NMR to observe their solution properties. The tricarbonylferrole unit was found to be static from ?125 to +95° C, while the π-Fe(CO)₃ group appeared to be fluxional over the same temperature range. Definite assignments of the carbonyl carbon and ferrole ring carbon resonances have been made. A low temperature single crystal X-ray study of Fe₂(CO)₅PPh₃(PhC₂Ph)₂ demonstrated that the phosphine ligand was attached to the ferrole iron contrary to previous belief based on chemical evidence.     

Solid-state reactions between alkali persulfates and oxides of corundum structure

The effects of three corundum structure oxides, α-Al₂O₃, α-Cr₂O₃, and α-Fe₂O₃, on the thermal decomposition of sodium and potassium peroxodisulfates (persulfates) under non-isothermal static air conditions and using various oxide/persulfate molar ratios, have been thermoanalytically investigated. Compounds such as Na₃Al(SO₄)₃, K₃Al(SO₄)₃, Cr₂(SO₄)₃, K₃Cr(SO₄₃, and Na₃Fe(SO₄)₃ are identified by X-ray diffractometry and conventional chemical analysis. The molar ratios as well as temperatures of the stoichiometric formation for these compounds have been established. At higher temperatures, α-Al₂O₃ acts as a promoter catalyst for the decomposition of pyrosulfate to sulfate, whereas α-Cr₂O₃ behaves as a retarder for the decomposition of persulfate. A eutectic mixture is formed between K₃Al(SO₄) and K₂SO₄ at 675°C. Also, K₃Fe(SO₄)₃ is identified as two crystalline phases.     

Synthesis and structure of the 1,1′-trimethylenebenzene- cyclopentadienyliron cation.

1,1′-Bis(3-phenylpropyl)ferrocene reacts with AlCl₃/Al inheptane to yield 1,1′trimethylenebenzenecyclopentadienyliron hexafluorophosphate (I). The structure of complex I was established by X-ray analysis.     

The crystal and molecular structure of bis(triphenylsilicon) carbodiimide

The structure of (Ph₃SiN)₂C has been determined by single crystal X-ray diffraction. The structure was solved by direct methods and refined to R = 0.071 for 593 independent diffractometer data. The crystals are rhombohedral, R$\text{3}$ with a = b = c 18.201(20) Å, α = β = γ = 48.82(2)°, and Z = 4. The three crystallographically independent molecules each have linear SiNCNSi chains lying along the crystallographic threefold axes; in two of the molecules the central carbon atom lies on a centre of symmetry. Principal mean bond lengths and angles are: Si, 1.696(25); SiC, 1.846(20); NC, 1.164(30); CC, 1.387(14) Å; CSi, 108.2(6); and CSiC, 110.8(6)°.     

A pressure-induced nonlayered structure of indium monoselenide

An X-ray diffraction study was made on a new polymorphic phase of InSe obtained by heating a layered crystal of the 3R(γ) polytype under pressures of 40 and 50 kbar and by quenching to ambient conditions. An analysis of the diffraction intensity data collected on precession and Debye photographs gave a monoclinic structure (space group C¹_2h) with four molecules in a unit cell. Upon transformation, new, short interatomic distances characteristic of covalent bonding are formed between indium and selenium atoms that were originally located in the adjacent layers. The structure is regarded as a modified version of the nonlayered InS-type structure. In the real structure of the high-pressure phase, however, there is a small amount of disorder in the orientation of the InIn bonds. Discussion is given on the reconstructive, layer-nonlayer transformation of InSe.     

The crystal structure of copper bromide telluride

The crystal structure of CuBrTe has been determined. The compound is tetragonal with unit cell dimensions a = 16.417Å, c = 4.711Å, Z = 16, and space group I4₁/amd. Three-dimensional counterdiffraction intensity data (MoKα) were refined with full-matrix least-squares to a conventional unweighted R of 0.066. The structure consists of infinite tellurium spirals with bromine tetrahedra interspersed. Two basic types of disordered copper atoms were found. One type is at the center of the bromine tetrahedra and has several possible locations for each atom. The other type of copper lies on two possible sites in a distorted tetrahedral environment with tellurium and two bromine atoms as nearest neighbors.     

The preparation and structure of (divinylcyclohexene)nickel—phosphine complexes

Butadiene reacts with (hexatriene)nickel—phosphine complexes to give (divinylcyclohexene)nickel derivatives; the structure of the product from the reaction involving octatriene has been determined crystallographically.     

Crystal growth,properties, and structure refinements of some rhenium phosphides and arsenophosphides

Small single crystals of Re₂P and Re₃P₄ were grown in a tin flux. Their crystal structures were refined from single crystal diffractometer data to residuals of R = 0.055 and R = 0.049, respectively. The new compound ReP_2.3 was prepared. Re₆P₁₃ forms an extended solid solution with As up to Re₆As_10.7P_2.3. Re₃P₄ is diamagnetic. ReP₄ is a diamagnetic semiconductor with a band gap of 0.54 eV. Systematic trends in the structural chemistry of rhenium phosphides are discussed.     

Single-crystal growth and crystal structure refinement of CuAlO2

Single crystals of the delafossite-type compound CuAlO₂ were grown from Al₂O₃Cu₂O melt by a slow-cooling method from 1200°C. Three types were found in as-grown crystals (single crystals, short-columnar twin crystals with concave angles, and laminar twin crystals). The twinning form is similar to the spinel-type twin. CuAlO₂ is rhombohedral, $\text{R}\text{3}\text{m, a = 2.8604(7), c = 16.953(5)}\text{A}\text{?}$, Z = 3, Dx = 5.12 g/cm³ and Dm = 5.06 g/cm³. The crystal structure of CuAlO₂ was analyzed by means of single-crystal X-ray diffraction with a conventional R value = 0.038. The value of the U₁₁ component of the thermal parameter of Cu⁺ was twice as large as U₃₃.     

The structure and magnetic properties of chromium(III) molybdate

Magnetic susceptibility measurements have shown that Cr₂(MoO₄)₃ orders magnetically at 42 K. Powder neutron diffraction experiments at 295 and 5 K indicate that Cr₂(MoO₄)₃ is chemically and magnetically isostructural with the L-type ferrimagnet Fe₂(MoO₄)₃, and has a magnetic moment of 2.5 ± 0.2 μ_B per cation at 5 K. The limitations imposed on powder neutron diffraction methods by particle-size effects are discussed.     

The crystal structure of Li2WO4II: A structure related to spinel

Li₂WO₄II, synthesized at 3 kbar and 630°C, has tetragonal symmetry, $\text{I4}{}_1\text{amd}\text{, a = 11.954(2)}$ and c = 8.410(1)Å, Z = 16, D_calc = 5.78 g cm^?3. The structure was determined by countermeasuring 469 independent reflections from a single crystal and was refined up to R = 0.032 by the full-matrix least-squares method. It is based on cubic closest packing of oxygen atoms and is closely related to the β-phase structure of Mg₂SiO₄. W and Li(2) are in octahedral sites and Li(1), in tetrahedral sites. Four Li(1)O₄ tetrahedra form a Li₄O₁₂ group, WO₆ and Li(2)O₆ construct a octahedral double chain along the a axis, and four WO₆ octahedra build a W₄O₁₆ group by sharing their octahedral edges.     

Electrical properties and defect structure of rutile slightly doped with Cr and Ta

The electrical conductivity of rutile doped with 0.3–3 at % Ta or 0.1–1 at % Cr is reported as a function of oxygen pressure in the temperature range 1273–1623 K. The results are discussed in terms of a point defect model, on assuming a charge compensation of foreign impurities by usual lattice point defects. In the case of Ta-doped materials, two kinds of charge compensation by an electronic or a lattice defect may occur, according to the oxygen pressure and temperature, the essential features of which are in good agreement with the theoretical analysis. While chromium is incorporated as a trivalent species under a reducing atmosphere, the lack of ionic conductivity due to compensating lattice defects prevents any definitive conclusion about the valence state of the foreign chromium cations under oxidizing conditions. Some additional information and some conclusions are drawn concerning the transport properties of pure or doped titanium dioxide at high temperature.     

Influence of M2+ ions substitution on the structure of lanthanum hexaaluminates with magnetoplumbite structure

A series of compounds with the initial composition LaM_xAl₁₁O_18+x has been studied with x ranging from 0 to 1, and M = Mn, Co, Cu. They exhibit a more or less distorted and defective magnetoplumbite arrangement. Their effective compositions have been determined by X-ray structure refinement. The smaller the content of M²⁺, the higher the disorder in the crystal lattice, the worse the crystal growth, and more intense the diffuse scattering in (001) planes. The role of M²⁺ is compared to that of M²⁺ stabilizing γ-Al₂O₃ to give MAl₂O₄ spinels.     

Intramolecular disorder and its relation to mesophase structure in lyotropic liquid crystals

NMR SPDE measurements are reported for the lamellar (dispersions and multibilayer stacks) and hexagonal phases of sodium octanoate/octanol/D₂O mixtures. In the lamellar L_β and L_γ (gel) phases the octyl chains are rigid and perfectly ordered, while in the lamellar L_α and hexagonal phases they are flexible and disordered. In particular, the measurements show that in the fluid lamellar L_α phase, there is a marked discontinuity in the octyl chain flexibility at the C₅-C₆ segment; this behaviour is identical to that previously reported for the alkyl end-chains in smectic 4,4′-di-n-octyloxyazoxybenzene. In contrast, in the hexagonal phase, there is an effectively continuous flexibility gradient along the whole length of the octyl chain as in nematic 4,4′-di-n-octyloxyazoxybenzene. The behaviour in the lamellar phase is attributed to interference between cooperative conformational modes and localized random thermal fluctuations.     

Preparation and structure of fluorite-type (Sr,Y)Cl2.05

Anion excess colorless fluorite-type strontium-yttrium chloride has been prepared. Single crystals of the SrY compound exhibit a primitive cubic lattice with a = 6.967(1)Å. Two mutually exclusive structural models for solutions, neither of which is exact, are discussed. The first is a vacancy model in which the extra charge which results from substitution of Y³⁺ for Sr²⁺ is balanced by the simultaneous removal of a Sr²⁺Cl^? ion pair. This model requires individual ion sites to be partially occupied and nonequivalent and is strongly suggestive of vacancy ordering. Refinement in space group P1, with sites refined independenty, led to R = 0.1096. The second model describes the structure in terms of a Willis cluster of defects and includes both anion vacancies and interstitial anions. Full-matrix least squares refinement in space group Fm3m, with positions analogous to those in UO_2.12 and (Ca,Y)F_2.10, converged at R = 0.0633 for the 114 face-centered parent structure reflections whose |F|;² > σ(F²). This second model is discussed in relation to a probable true solution which involves longrange order.     

Synthesis, X-ray structure and reactions of phenylimidodecamethylvanadocene

The synthesis and X-ray structure of phenylimidodecamethylvanadocene are described. Its reactions with electrophiles, including isocyanides, which lead to loss of one pentamethylcyclopentadienyl ring (Cp) are reported.