Solid state reactions to CdTeMoO6 and its structural characterization

CdTeMoO₆ has been obtained by solid state reactions of CdMoO₄ with orth. TeO₂ at 425°C, with tetr. TeO₂ at 470°C, and with H₆TeO₆ at 490°C. Its crystal structure belongs to the tetragonal system (space group $\text{P4}\text{n}$ or $\text{P4}\text{nmm}$ with unit cell dimensions a = 5.279(2) Å, c = 9.056(2) Å. The specificity of this compound in the allylic oxidation reactions should be strictly related to its structural features, among which the presence of cis MoO₂ groups could be very important.     

The lowest quartet state of copper porphin: Zeeman experiments at 4.2 K

Zeeman experiments in a magnetic field of 75 kG on copper porphin in a single crystal of n-octane prove the lowest metastable state to be a quartet as predicted by Gouterman and colleagues. In zero magnetic field this quartet is split into two degenerate pairs, the ±$\text{1}\text{2}$ components lying at about 0.7 cm^?1 higher energy than the ±$\text{3}\text{2}$ components.     

A quadratically convergent reference state optimization procedure

A quadratically convergent procedure for the optimization of multiconfigurational reference states is presented and analyzed. The optimal reference state is determined from the energy variation principle by means of a sequence of unitary transformations of the form exp(i$\text{Λ}$exp(i$\text{k}$, where the hermitean operators $\text{Λ}$ and $\text{k}$ generate transformations of orbitals and correlation coefficients, respectively. Sample calculations are carried out within the Pariser—Parr—Pople model using a correlated reference state suggested by Clementi and Veillard. For the systems considered so far, convergence is achieved after 2–4 transformations.     

Crystal engineering in the solid state photochemistry of cyclohexenones

Previous results from our laboratory plus a simple conformational analysis argument lead to the prediction that irradiation of cyclohexenone $\text{1}$ in the solid state will give ketol $\text{2}$. An independent synthesis of $\text{2}$ plus a determination of the solid state conformation of $\text{1}$ by X-ray crystallography show this prediction to be correct.     

Conformation-specific photochemistry in the solid state

The unsymmetrical ene-dione $\text{1b}$ exists in solution as a mixture of two conformational isomers, A and B, in rapid equilibrium. Irradiation of $\text{1b}$ in this medium leads to four products, two from each conformer. In the solid state, however, compound $\text{1b}$ adopts a single conformation (A), and photolysis of crystals of $\text{1b}$ leads to a single product. The formation of one rather than two photoproducts in this instance is attributed to a unique solid state steric effect, termed steric compression.     

Reactions of cyclo-octatetraene and its derivatives - X: 1,2,3,8-Tetraphenylcyclo-octatetraene and 2,3,4,5-tetraphenylcyclo-octa-1,3,5-triene

The reaction of tetracyclone $\text{1b}$ with the cyclo-octatetraene-dimethyl acetylenedicarboxylate adduct $\text{2}$ at $\text{ca}$. 110° produces, in addition to the $\text{exo}$[4+2] Π cycloadduct $\text{3b}$ (49%), 1,2,3,8-tetraphenylcyclo-octatraene $\text{5}$ (11%), together with the diketone $\text{11}$ (5%). In a similar reaction with the esterified cyclo-octatetraene-maleic anhydride adduct $\text{13a}$, the major product $\text{14}$ (82%) is accompanied by the cyclohexa-1,3-diene $\text{15}$ and the dihydrosemibullvalene derivative $\text{16}$. Thermolysis of $\text{3b}$ at $\text{ca}$. 145° leads to the cyclobutene $\text{12}$., which on catalytic hydrogonation followed by decarbonylation at 180°–190° gives 2,3,4,5-tetraphenylcyclo-octa-1,3,5-triene $\text{19}$. Attempted thermal conversion of $\text{19}$ into a dihydrosemibullvalene failed.     

Condensation of a p-diazooxide with dimethyl acetylenedicarboxylate: formation of a spiro [4.5] Decatetraenone and a nonenolizable naphthalenone in a single reaction

The condensation of p-diazooxide $\text{1}$ with dimethyl acetylenedicarboxylate at 90°–100°C yields two C₂₆H₃₂O₉ products, corresponding to addition of two molecules of ester to one of the carbene $\text{2}$. The major product is the novel spirodecatetraenone $\text{4}$, and the minor product is the remarkable, nonenolizable naphthalenone $\text{5}$. Spirodecatetraenone $\text{4}$ is not a precursor of $\text{5}$, since the former is stable to acids and rearranges only above 200° to give the blocked azulenone $\text{8}$. A mechanism for the concomitant formation of product $\text{4}$ and $\text{5}$ is proposed.     

Reaction selectivity in solid state photochemistry

Steric compression, arising from intermolecular or intermolecular H...H non-bonded repulsive interactions generated along the reaction pathway, is used to explain abnomal solid state photoreactivity. Computer simulations of the motions involved in each case, with calculations of the resulting non-bonded steric compression energies were performed. Three systems were studied: ($\text{A}$) Enone photorearrangements, where the observed changes in the solid state photoreactivity of eight closely related α,β-unsaturated cyclohexenones are correlated with their crystal and molecular structures as determined by X-ray diffraction methods. ($\text{B}$) Failure of [2+2] photocycloadditilon of an α,β-unsaturated ketone when irradiated in the solid state despite an almost perfect crystal lattice alignment of the potentially reactive double bonds. ($\text{C}$) An unsymmetrically substituted ene-dione for which solution photoreactlon results in four products and solid state photoreaction yields only one.     

Photoisomerization of benzylidenephosphine containing phosphorus in low coordination state

$\text{E}$-Benzylidene-$\text{P}$-2,4,6-tri-$\text{t}$-butylphenylphosphine containing phosphorus in low coordination state was irradiated to give the corresponding $\text{Z}$-isomer: both isomers were isolated and characterized and the reactions with chromium(O) carbonyls were described.     

Excited triplet state spectroscopy in the infrared

A new method for the investigation of the infrared spectra of metastable $\text{excited}$$\text{electronic}$ states is presented. With a Fourier Transform infrared spectrometer as the probe and a CW Xe lamp source as the pump, the infrared spectrum of the lowest triplet state of triphenylene isolated in a N₂ matrix at 15K has been examined. CH out-of-plane wagging modes are prominent and shifted from their ground state frequencies. It is expected that when fully developed this method will provide important information on excited state force constants and potential energy surfaces.     

Kinetics and mechanism of the reaction of Ba(No3)2 with TiO2(anatase) in the solid-solid state and the liquid-solid state

The reaction of Ba(NO₃)₂ with TiO₂(anatase) was studied by TG and DTA. According to simultaneous TG and DTA, the reaction occurred sharply around the melting temperature of Ba(NO₃)₂, ～577°C, at low heating rates, and the reaction followed after melting of Ba(NO₃)₂ as the rate was raised. For the isothermal reactions the conversion α vs time relationship was given by the equation: kt = 1 - (1-α)^1/3. The relationship was shown by one straight line below 577°C, and by two lines with a bend above 577°C. The reaction rates at the earlier period above 577°C were about $\text{1}\text{5}$ smaller than those at the later period, which were nearly on the extrapolated log k vs 1/T line obtained below 577°C. The activation energy was 212 kJ mol^?1 for the solid-solid reaction and 231 kJ mol^?1 for the earlier period in the liquid-solid reaction.     

Gas chromatographic stationary phase properties of two room-temperature liquid organi salts

The gas chromatographic properties of two room-temperature liquid organic salts, triethyl-n-hexylammonium triethyl-n-hexylboride (TEHAB) and stearylmethyldipolyoxethyl(15)ammonium chloride (Ethoquad $\text{18}\text{25}$, are described. Triethyl-n-hexyl-ammonium triethyl-n-hexylboride could be used up to temperatures of 130°C but showed poor stability towards air and undesirable reactivity towards some dipolar and proton donor/acceptor solutes when used as a column packing material. In contrast, Ethoquad $\text{18}\text{25}$ had a maximum column operating temperature of 280°C, or 300°C after vacuum conditioning. From a calculation of mcReynolds' phase constants and the molar free energy, enthalpy, and entropy of solution for polarity test probes, it was established that Ethoquad $\text{18}\text{25}$ showed intermediate selectivity for dipolar and proton-donor solutes compared to results for conventional non-ionic phases. Ethoquad $\text{18}\text{25}$ is an excellent phase for the profiling of essential oils.     

The crystal structure of N-sodiohexamethyldisilazane,Na[N{Si(CH3)3}2]

The crystal structure of Na[N{Si(CH₃)₃}₂] has been determined from single-crystal x-ray diffraction data collected by counter methods. N-sodiohexamethyldisilazane crystallizes in the mono-clinic space group p21/n with unit cell parameters $\text{a}$ = 9.426(3), $\text{b}$ = 6.921(3), c = 17.974(5)Å, β = 93.83(2)°, and ?_calc = 1.04 g cm^?3 for z = 4 formula units. Least-squares refinement gave a final conventional R value of 0.034 for 1244 independent observed reflections. In the solid state the compound exists in a polymeric arrangement with an average Na-N distance of 2.355(4)Å. The methyl group are configured such that the angle of rotation of the trimethylsilyl moiety about the Si-N bond is 30° from the eclipsed position. The Si-N bond length is 1.690(5)Å, and the Si-N-Si bond angle is 125.6(1)°.     

Phase equilibria for the separation of aromatic and nonaromatic compounds using mixed solvents. Part I. The system n-heptane—toluene—N-methylpyrrolidone/monoethyleneglycol

The solvent combination of N-methylpyrrolidone (NMP) and monoethyleneglycol (MEG) is used in industry for the separation of aromatics and nonaromatics (Arosolvan process).In this paper experimental results obtained for the system n-heptane—toluene—N-methylpyrrolidone/monoethyleneglycol are presented. Liquid—liquid equilibrium compositions were obtained at three different temperatures (50°C, 60°C, 70°C). For each temperature, three different solvent compositions corresponding to weight ratios of NMP/MEG equal to $\text{50}\text{50}$, $\text{62}\text{38}$ and $\text{70}\text{30}$ were considered. The different sets of experimental results obtained are correlated using the NRTL equations.Equilibrium compositions obtained using an industrial solvent mixture (NMP/MEG-$\text{58}\text{42}$) are compared with data based on the use of purified solvents.     

The crystal and molecular structure of μ-μ-dichlorobis(hexafluorobut-2-enyl)-bis(cycloocta-1,5-dienyl)diiridium(III).

The title compound is isolated from reaction of hexafluorobut-2-yne with μ-μ-Dichlorobis(cycloocta-1,5-diene)diiridium(I) at 90°C. Crystals of the complex, solvated with deuterobenzene, are monoclinic, space group $\text{P}$2₁/$\text{n}$ with $\text{a}$ = 10.97 $\text{+}$ 0.02, $\text{b}$ = 17.96 $\text{+}$ 0.03, $\text{c}$ = 11.63 $\text{+}$ 0.02 », β = 127.4 $\text{+}$ 0.60°. The acetylene has abstracted a hydrogen atom forming a σ-bonded $\text{cis}$-vinylic group and the original cyclooctadiene, having lost a proton, is coordinated as the cycloocta-1,5-dienyl ligand. Mean bond lengths are IrCl 2.467, IrC (allylic) 2.17, IC (olefinic) 2.36 and IrC (vinylic) 2.09 ».     

Some solid state properties of enantiomers and their racemates

Heats of sublimation and fusion for l and dl-menthol, d and dl-carvoxime and d and dl-dimethyl tartrate were measured. Values of 22.9, 18.8, 21.7, 24.3, 18.5 and 26.9 $\text{kcal}\text{mole}$ and 18.2, 15.7, 24.3, 30.9, 23.3 and 36.2 $\text{cal}\text{g}$ were obtained for heats of sublimation and fusion respectively. Heats of sublimation are believed known to ±5% while heats of fusion are believed qualitatively correct. Generally good agreement was observed with literature values when available. Higher heats of fusion and sublimation are observed for the enantiomer or racemate with the higher fusion temperature. Correlation of these physical properties with the phase diagram for fusion and solubility suggest that differences in the temperature dependence of vapor pressure and solubility might be useful diagnostic tests for discontinuities in molecular packing and phase behavior in the solid state. Prediction of the temperature where racemic mixture to conglomerate transitions occur would be extremely useful for resolving racemates.     

Studies on organophosphorus compounds XLVII preparation of thiated synthons of amides,lactams and imides by use of some new p,s-containing reagents

The thionation properties of 2,4-bismethylthio-1,3,2,4-dithiadiphosphetane 2,4-disulfide, $\text{1}$, 2,4-bis(4-phen-oxyphenyl)-1,3,2,4-dithiaphosphetan is that $\text{2}$, $\text{3}$ and thionate most amides and lactams In THF at room temperature (reaction time 5 min) to give the corresponding thionated compounds. Imides are easily thionated by $\text{2}$, $\text{3}$ and $\text{4}$ In DME at 60 °C. The reactions of $\text{1}$ with amides, imides and most lactams are run at 60°C to give good yields of the corresponding thionated compounds.     

Fluorescence of ammonia-d3 from its first excited singlet state

Structured emission spectra have been observed from ND₃ excited at 2139 Å and 2144 Å. The emission is short-lived (τ_{$\text{1}\text{2}$} < 10^?10 s) and has been assigned to the ND₃($\text{A}$) → ND₃($\text{X}$) fluorescence transition.