Effect of pressure on the conductivities of HCl and KCl in water at 0°C

The electrical conductivities of hydrochloric acid and potassium chloride in water have been measured in the concentration range of 3×10 ^–4 –10 ^–3 moles-dm ^–3 at 0°C up to 3500 bar. The limiting molar conductance (₀) for HCl increases with increasing pressure, while ₀(KCl) has a maximum around 1700 bar. The excess conductance of hydrogen ion [ ₀ ^E =₀(HCl)–₀(KCl)] increases with increasing pressure. Its pressure dependence indicates that the reorientation of water molecules, which is the rate-determining step in the proton jump, becomes faster at higher pressure. This anomaly is attributed to the distortion with pressure of the hydrogen bonds in water.     

The association of sodium cholate in NaCl and urea solutions

The association of sodium cholate, SC in NaCl and urea solutions at 25 °C has been investigated using laser light scattering and conductivity techniques. The light scattering results show that the mean translational diffusion coefficient, ¯D _h decreases as SC and/or NaCl increase and SC forms secondary aggregates in solutions of high ionic strengths.The addition of urea decreases the equivalent conductance, _eq of SC and a further lowering of _eq occurs as urea concentration increases. This effect becomes more pronounced when urea is substituted by an alkyl group and an additional decrease in _eq is found with increasing alkyl chain and/or concentration. The present results provide the evidence that SC associates progressiveley and ureas decrease the hydrophobic interactions between the solvent and SC monomer resulting in less association in solutions.     

Pressure effect on proton jumps in dioxane-water mixtures at 25°C

The limiting molar conductances ^o of hydrochloric acid and potassium chloride in 2.5, 5, 10, and 15 mol% 1,4-dioxane-water mixtures were determined at 25°C as a function of pressure up to 196.1 MPa from the conductances measured in the dilute concentration range. The value of ^o(HCl) was two to three times larger than that of ^o(KCl) in each solvent mixture as well as in pure water. The excess proton conductance, as estimated by the equation [ _E ^o =^o(HCl)–^o(KCl)], increased with pressure in each solvent mixture, although the value of _E ^o itself decreased rapidly with an increase in the dioxane content. The rate of increase in _E ^o with pressure was not so large in dioxane-water mixtures as in pure water, and became smaller with an increase in the dioxane content in contrast to the cases of ethanol-water and t-butyl alcohol (TBA)-water mixtures. These results are discussed in terms of the difference between a dioxane and an ethanol or a TBA molecule in ability to stabilize the hydrogen-bonded networks of water in the water-rich region.     

Triterpene glycosides of alfalfa. III. Medicoside I

On the basis of chemical transformations and with the aid of physicochemical results, the structure of glycoside I isolated from the roots of the plantMedicago sativa has been established as hederagin 3-O-[O--L-arabinopyranosyl-(1 2)--D-glucopyranosyl-(1 2)--L-arabinopyranoside] 28-O--D-glucopyranoside. Compound (I), C₅₂H₈₄O₂₂, mp 210–212°C, [] _D ²¹ +38.4° (c 1.48; methanol). Acid hydrolysis of (I) led to hederogenin (II) — C₃₀H₄₈O₄, mp 326–330°C, [] _D ²³ +84.2° (c 0.19; pyridine. The Hakomorimethylation of glycoside (I) yielded the permethylate (IV) — C₆₅H₁₁O₂₂ [] _D ²³ +41.6° (c 1.79; methanol). The GLC analysis of the products of the methanolysis of compound (IV) showed the presence of 3,4,6-tri-O-methyl-D-glucopyranose, 2,3,4,6-tetra-O-methyl-D-glucopyranose, 3,4-di-O-methyl-L-O-arabinopyranose, and 2,3,4-tri-o-methyl-L-arabinopyranose. The alkaline hydrolysis of glycoside I gave compound (III) with mp 230–233°C, [] _D ²¹ +35.2° (c 0.21; methanol), which was identified as medicoside C. Details of the PMR spectrum are given for compound (IV) and of the IR spectrum for compound (I).Institute of the Chemistry of Plant Substances of the Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 607–610, September–October, 1986.     

Enthalpies of formation and O-O and C-O bond strengths in polyoxides RO x R′ and RO x

Bond strengths in RO-OOR, ROO-OH, and ROO-OOR (R, R = H, Me, Et, and Bu) molecules, calculated by the semiempirical quantum-chemical methods, were used to determine the enthalpies of formation of polyoxides RO _x R (x = 3, 4) and related radicals and the bond strengths (D/kcal mol^–1) in these molecules:D(ROOO-OR) = 33.2±0.9,D(ROOO-OH) = 37.5±0.7,D(R-O _x R) = 76.0±1.2,D(H-000) = 58.6,D(R-000) = 42.8±0.8. A new value of Benson's polyoxide thermochemical increment, _f H°[O-(O)₂] = 11.1±1.0 kcal mol^–1, was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2190–2193, September, 1996.     

Some remarks on the periodical change of the stability constants of the lanthanide complexes

The correlations between the values of the lgK (K = stability constant of the lanthanide complex) and the reciprocal of the ionic radius 1/r or the sum of the ionization potentials ₁ ³ I for the lanthanide ions were reviewed for different ligands. A straight-line relationship (lgK – lgK)/lgK vs. (1/r – 1/r)/(1/r) or vs. ( ₁ ³ I – ₁ ³ I)/ ₁ ³ I was found within the tetrads La-Nd, Gd-Ho, and Er-Lu.

---

Bemerkungen zum periodischen Wechsel der Stabilitätskonstanten von Lanthaniden-Komplexen

Zusammenfassung Es wurde eine Übersicht der Korrelationen zwischen den Werten von logK (K = Stabilitätskonstante der Lanthanidenkomplexe) und den reziproken Ionenradien 1/r oder der Summe der Ionisierungspotentiale ₁ ³ I für die Lanthanidenionen für verschiedene Liganden gegeben. Dabei wurde eine lineare Korrelation für (lgK – lgK)/lgK gegen (1/r – 1/r)/(1/r) oder gegen ( ₁ ³ I – ₁ ³ I)/_1/3 I innerhalb der Tetraden La-Nd, Gd-Ho und Er-Lu aufgefunden.

     

Ionic interactions in solutions. III. Derivation of the ″associated″ electrolyte formulation from the Onsager treatment of conductance

The system of equations of the Onsager treatment of conductance is rederived in a systematic way by the use of several sets of hierarchy equations generalizing to other quantities the classical Born-Bogoliubov-Green-Kirkwood-Yvon (BBGKY) hierarchy of internal force. The monitoring term of the Onsager continuity equation obtained is compared to former theoretical studies. It is inferred in particular that the perturbation on the anion-cation pair distribution for a symmetrical binary electrolyte is proportional not only to the external fieldX but also to the conductance coefficientf _A=1+X/X+ _el/ ₀. This result, called the echo effect, leads to a new formulation of molar conductance which shows a great similarity to the empirical conductance function obtained by grafting the chemical model of Bjerrum onto the conductance equations derived on the basis of the Debye approximations as proposed formerly by the author from experimental observations. The result allows a simple generalization of the conductance equation to any direct short-range anion-cation energy-potential model.     

Conductivity of Sodium Chloride in Water + 1,4-Dioxane Mixtures at Temperatures from 5 to 35°C I. Dilute Solutions

The molar and single-ion conductivities of dilute solutions of sodium chloride (C<0.01 mol-dm^–3) in binary mixtures of 1,4-dioxane with water were measured covering a broad solvent composition range at temperatures from 5 to 35°C. Accurate viscosity and permittivity data were determined for the organic solvent system. Evaluation of the limiting molar conductivity , ionic conductivities. ₊ , and _– , and the association constant K _A is based on the chemical model of electrolyte solutions, including short-range forces.     

Conductance of Selected Alkali Metal Salts in Aqueous Binary Mixtures of 2-Methoxyethanol at 25°C

Precise conductance measurements have been performed for lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, sodium perchlorate, and sodium tetraphenylborate in 2-methoxyethanol–water mixtures at four different mole fractions, i.e., 0.056, 0.136, 0.262, and 0.486 of 2-methoxyethanol (69.73 D 26.55) at 25°C in the concentration range 0.0004–0.0642 mol-dm^–3. The limiting molar conductivity °, the association constant K _A, and the association distance R for the solvent mixtures have been evaluated from the conductance concentration data using the 1978 Fuoss conductance equation. The single-ion conductances have been estimated using the reference electrolyte tetrabutylam-monium tetraphynylborate(Bu₄NBPh₄). The analysis of the data indicates that for most salts ion association is appreciable in the solvent mixtures with a mole fraction of the cosolvent of 0.262 or higher. The results have been interpreted in terms of ion-solvent interactions and structural changes in the mixed solvent media.     

Cardiac glycosides ofAcokanthera venenata

Six cardenolides have been isolated from the leaves ofAcokanthera venenata G. Don: AV-1, mp 252–255°C, [] _D ²⁰ +39.4° (MeOH); AV-2, mp 199–208°C, [] _D ²⁰ -59.3° (MeOH); AV-3, mp 269–275°C/300–304°C, [] _D ²¹ –69.8° (MeOH); AV-4, mp 279–289°C; AV-5, mp 222–225°, [] _D ²⁰ -64.3° (MeOH); and AV-6, mp 193–196°C [] _D ²⁰ –23.8° (MeOH — CHCl₃). AV-5 has been identified as acovenoside A. AV-3 is a new cardiac glycoside: it is 1-acetoxy-3-(4-O--D-glucosyl-3-O-methyl--L-talomethylosyloxy)-14-hydroxy-5, 14-card-20(22)-enolide (glucoacovenoside B).Khar'kov State Pharmaceutical Institute. All-Union Scientific Research Institute of Drug, Chemistry and Technology, Khar'kov. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 372–376, May–June, 1987.     

Percolation Effects on the Surface of a Polyimide Film Modified with Aqueous Solutions of an Alkali and Acid

A cluster structure of the surface of a polypyromellitimide film was studied by the electron microscopy and ATR IR spectroscopy methods at different steps of consecutive treatment with aqueous solutions of an alkali and acid. The effective size and fractal dimension D of polyamidoacid clusters, as well as the degree _s of the filling of the surface with the latter were calculated from the data of the electron microscopy as a function of the degree of imide group conversion into amidoacid units on the film surface. The _s and D parameters were shown to increase with a rise in : _s = 0.1–0.3 and D = 1.3–1.4 at < _cr and _s 0.6 and D 1.7 at > _cr, where _cr is a critical degree of conversion, which corresponds to the formation of a continuous physical network of polyamidoacid macromolecules or a percolation cluster. In a region close to _cr (at < _cr), the correlation length land the concentration C of the clusters vary according to the laws of the percolation theory for two-dimensional lattices: l (_cr – )^– and C (_cr – ), where = 1.3 ± 0.1 and = 0.67 ± 0.05.     

Thermal and other studies on bivalent metal selenltes

BaSeO₃·2·5H₂O(I), PbSeO₃· 2H₂O(II) and CdSeO₃·3.5H₂O(III) were prepared and analysed. Their hygroscopicity and solubility was investigated. These compounds have high thermal Stability, as shown by their TG and DTA data. IR spectra show multi-dentate coordination of selenite to cations, due to considerable splitting of the asymmetric v₃ and v₄ bands of SeO ₃ ^{2 –} in the 780-730 cm^–1 and 420-325 cm^–1 region.Tentative structures have been proposed involving bridging oxygen atoms.

---

Zusammenfassung BaSeO₃-2.5H₂O(I), PbSeO₃ · 2H₂O(II) und CdSeO₃· 3.5H₂O(III) wurden hergestellt, analysiert sowie deren Hygroskopizität und Löslichkeit untersucht. TG- und DTA-Untersuchungen erweisen die hohe thermische Stabilität dieser Verbindungen. Die IR-Spektren zeigen mehrzählige Koordination von Selenit zu Kationen, was aus einer beträchtlichen Aufspaltung der antisymmetrischenv ₃ undv ₄ Banden von SeO ₃ ^{2 –} im Bereich 780-730cm^–1 bzw. 420-325 cm^–1 hervorgeht. Es wurden versuchsweise Strukturen mit überbrückenden Sauerstoffatomen vorgeschlagen.

---

BaSeO₃· 2,5H₂O, PbSeO₃ · 2H₂O CdSeO₃ · 3,5H₂O . . - , v ₃ v ₄ SeO ₃ ² }- 780-730 420-325 ^–1. , .

     

Interaction of PM12?nVnO40?(3+n) (M=Mo, W) heteropoly complexes with nitrogen oxide

In aqueous solution, PM_12–nV_nO₄₀ ^–(3+n) (M=Mo,W) hetero-polyanions provide a much faster oxidation of NO than mononuclear VO ₂ ⁺ ions, yielding HNO₂, NO ₃ ^– and reduced HPA.

---

, PM_12–nV_nO₄₀ ^–(3+n) (M=Mo,W) , VO ₂ ⁺ , NO HNO₂ NO ₃ ^– .

     

Conductance of aqueous NaCl solutions at pressures up to 2000 atm

Electrical conductance measurements are reported for aqueous NaCl solutions at 25°C as a function of concentration up to 0.02M and pressures up to 2000 atm. The data were analyzed with the Fuoss-Hsia-Fernandez-Prini (FHFP) equation. The standard error of fit, , varies from 0.04 at 1 atm to 0.10 at 2000 atm. The increase of with pressure arises from increasing non-randomness in the distribution of errors about the FHFP equation suggesting that modifications in the theory are necessary. The pressure dependence of _O for NaCl and KCl is nearly identical.Contribution of the Scripps Institution of Oceanography, New Series     

The phenomenon of conglomerate crystallization: XXXVII: The crystallization behavior of the Cr(III) and Co(III) amine carbonates [Cr(en)2CO3]I (I) and NH4{[cis-β-Co(trien)Co3]2}(PF6)3 (II)

[Cr(en)₂CO₃]I (I), ICoO₃N₄C₅H₁₆, crystallizes from water at 21°C in space groupP2₁/c (no. 14), with lattice constantsa=7.298(4),b=8.622(8),c=17.577(6)Å,=91.29(4)°;V=1105.59 ų andd(calc; MW=359.11, Z=4)=2.157 g cm^–3. A total of 2825 data points were collected over the range of 4°250°; of these, 1855 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=37.657 cm^–1) and the transmission coefficients ranged from 0.4850 to 0.9991. The finalR(F) andR _w(F) residuals were, respectively 0.134 and 0.113. The cations exist in the lattice as the enantiomeric pair () and (). NH₄{[cis--Co(trien)CO₃]₂}(PF₆)₃ (II), Co₂P₃F₁₈O₆N₉C₁₄H₄₀, crystallizes from water at 21 °C in space groupP2₁/c (no. 14), with lattice constantsa=10.397(2),b=20.292(3),c= 27.082(4) Å,=100.30(3)°;V=3545.70 ų andd(calc; MW=983.29, Z=4)=1.842 g cm^–3. A total of 3724 data were collected over the range of 4°250°; of these, 2653 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=12.031 cm^–1) and the transmission coefficients ranged from 0.8326 to 0.99985. The finalR(F) andR _w (F) residuals were, respectively 0.104 and 0.124. The cations exist in the asymmetric unit as() and()[cis--Co(trien)CO₃]⁺ pairs. The three independent PF₆ ^– anions exhibit the usual high thermal motion typical of these species and the NH₄ ⁺ cation is either disordered or exhibits high thermal motion also (its H atoms could not be found in difference maps).     

Synthesis of some 5′-O-amino acid derivatives of uridine as potential inhibitors ofUDP-glucuronosyltransferase

Summary In an attempt to develop potential inhibitors ofUDP-glucuronosyltransferase, some 5-O-amino acid derivatives of uridine were synthesized. N-protectedL-amino acids were coupled at the 5-O-position of 2,3-O-isopropylideneuridine by esterification employing the method of symmetrical anhydrides in presence of 4-dimethylaminopyridine, 5-O-(N-benzyloxycarbonyl-O-tert.butyl-L-threonl)-23-O-isopropylideneuridine (1), 5-O-(N-tert.butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylideneuridine and (2), 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (3), and 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (4) were obtained in good yield after column chromatography on silica gel. The treatment of2 withTFA/CH₂Cl₂ (6:1) at room temperature for 30 min led to a selective removal of theBoc group without deblocking of the 2,3-O-isopropylidene group of uridine. Treatment of2 withTFA/H₂O (5:1) at room temperature for 1 h, however, released bothBoc and 2,3-isopropylidene groups. TheZ group of1 was deprotected by catalytic hydrogenolysis over 10% Pd/C/ammonium formate.

---

Synthese von 5-O-Aminosäurederivaten des Uridins als potentielle Inhibitoren derUDP-Glukuronosyl-Transferase

Zusammenfassung In einem Versuch, potentielle Inhibitoren derUDP-Glukuronosyl-Transferase zu entwickeln, wurden einige 5-O-Aminosäurederivate des Uridins synthetisiert. N-GeschützteL-Aminosäuren wurden durch Veresterung mit der 5-O-Position des 2,3-isopropylidenuridins gekuppelt (Methode der symmetrischen Anhydride in der Gegenwart von 5-Dimethylaminopyridin). Solcherweise wurden 5-O-(N-Benzyloxycarbonyl-O-tert.butyl-L-threonly)-2,3-O-isopropylidenuridin (1), 5-O-(N-tert.Butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylidenuridin (2), 5-O-(N-tert.Butyloxycarbonyl-L-leucyl)-2,3-O-isopropylidenuridin (3) und 5-O-(N-tert.Butyloxycarbonyl-L-valyl)-2,3-O-isopropylidenuridine (4) nach Säulenchromatographie (Kieselgel) in guter Ausbeute hergestellt. Die Behandlung von2 mitTFA/CH₂Cl₂ (6:1) bei Zimmertemperatur (30 min) führte zu einer selektiven Abspaltung derBoc-Gruppe ohne Deblockierung der 2,3-O-Isopropylidengruppe des Uridins. Eine Behandlung von2 mitTFA/H₂O (5:1) bei Zimmertemperatur für 1 Stunde führte hingegen zur Abspaltung sowohl derBoc als auch der 2,3-O-Isopropylidengruppe. DieZ-Gruppe von1 wurde durch katalytische Hydrogenolyse auf 10% Pd/C/Ammoniumformiat abgespalten.

     

Synthesis and Crystal Structures of Copper(I) Complexes with N-Allylhexamethylenetetraminium Chloride Obtained in Different Acidic Media

The crystals of [(CH₂)₆N₄(C₃H₅)]Cu₂Cl₃ (I), [(CH₂)₆N₄(C₃H₅)]Cu₂Cl₃ (II), and [(CH₂)₆N₄(C₃H₅)]CuCl₂ (III) complexes were electrochemically synthesized (ac) from CuCl₂ · 2H₂O and N-allylhexamethylenetetraminium chloride in ethanol solutions at pH 6, 4.5, and 3. Their structures were determined using X-ray diffraction analysis (DARCh diffractometer, MoK radiation, /2 scan mode). Complex Icrystallizes in the monoclinic system: space group A2/a, a = 24.812(6) Å, b = 8.855(3) Å, c = 12.080(2) Å, = 89.21(3)°, and Z = 8. Complex II crystallizes in the triclinic system: space group P , a = 7.618(2) Å, b = 7.048(2) Å, c = 13.150(3) Å, = 97.50(2)°, = 92.70(2)°, = 100.74(2)°, and Z = 2. The crystals of complex III are orthorhombic: space group Pmn2₁, a = 7.478(2) Å, b = 8.827(2) Å, c = 9.662(3) Å, Z = 2. The organic cation in complex I acts as a tridentate ,,-ligand; that in complex II, as a bidentate ,-ligand. In complex III, the organic cation is involved in coordination with the copper(I) atom only through one nitrogen atom.     

First and second thermodynamic mixing properties of ethylbenzene +n-alkanes: Experimental and theory

Isobaric expansibilities _P and isothermal compressibilities _T have been determined at 25 and 45°C for binary mixtures of ethylbenzene + n-tetradecane and + n-hexadecane and the corresponding excess functions (V ^E /T)_P and (V ^E /P)_T have also been obtained. With these data and supplementary literature values, the following second order mixing properties are also reported at 25°C: _S ^E , (V ^E /P)_T, C_V and (VT). All mixing quantities have been compared with the results obtained at 25°C by using the Prigogine-Flory-Patterson theory of liquid mixtures. The predicted values suggest that the ability of ethylbenzene as a breaker of the pure n-C_n orientations is similar to what we found for toluene and higher than for p-xylene.     

Preparation et proprietes physico-chimiques de l'hydrure d'aluminium AlH3γ

Résumé AlH₃ a été synthétisé. La décomposition thermique de cet hydrure ainsi que la désolvatation de Al(AlH₄)₃, (C₂H₅)₂O ont été étudiés par analyse thermogravimétrique. L'analyse thermique différentielle effectuée sur AlH₃ montre un effet exothermique dû au passage à la forme AlH₃ puis endothermique correspondant à la décomposition de la phase formée. Une structure type alanate est proposée pour AlH₃ .

---

Aluminium hydride has been synthetised. Thermogravimetry has been used to investigate the thermal decomposition of this phase and the desolvation of A1(AlH₄)₃· (C₂H₅)₂O. Differential thermal analysis of-AlH₃ shows an exothermic effect due to transformation to -A1H₃, followed by the endotherm of -AlH₃ decomposition. A structure of alanate type is proposed for -AlH₃.

---

Zusammenfassung -AlH₃ wurde synthetisiert. Die thermische Zersetzung dieses Hydrids sowie die Desolvatation von Al(AlH₄)₃·(C₂H₅)₂O wurden mittels Thermogravimetrie untersucht. Die Differentialthermoanalyse von-AlH₃ zeigt einen dem Übergang in die AlH₃ -Form entsprechenden exothermen und mit nachfolgenden endothermen Effekt, welcher der Zersetzung der gebildeten Phase entspricht. Eine Struktur von solvatfreien Alanat-Typ wird für-AlH₃ vorgeschlagen.

---

- . l(l₄)₃. (C₂H₅)₂O . l₃ , l₃. lH₃ .

---

---

Ce travail a été effectué dans le cadre d'un contrat de recherches passé par le Laboratoire de Chimie Minérale avec la Direction des Recherches et Moyen d'Essai. Nous remercions bien vivement cet organisme ainsi que le Centre de Recherches ELF ERAP de Solaize de l'aide qu'ils nous ont apportée.     

Stereochemistry of planarchiral compounds,part XIII: Crystal structure of Meso-10,10′-dibromo-2,2′-bi-(1,6-methano-[10]-annulenyl)

Summary Crystallization of the mesoform of the title compound1 from benzene-pentane in the presence of 5% of (+)(R) _p (S) _a (R) _p -1 afforded crystals, the structure of which was determined in the achiral spacegroup P2₁/a-C _2h ⁵ . The configuration (R) _p (S) _p was confirmed, the torsional angle around the 2,2-bond is 68.6° and 72.1° (C3-C2-C2-C3 and C1-C2-C2-C1, resp.). The twist of the best planes through the perimeter carbonatoms 3, 4, 5 and 7, 8, 9 (3, 4, etc., resp.) is 26.0° and 19.8°. The colours of the crystals of the stereoisomers of1 depend on the torsional angles and thereby on the conjugation of the -systems. Meso, monoclinic (70.3°): light yellow; racemate, opt. inactive (56.2°): yellow; enantiomer of the racemate (34.4°): orange (average -values).

---

Stereochemie planarchiraler Verbindungen, 13. Mitt.: Die Kristallstruktur von Meso-10,10-dibrom-2,2-bi-(1,6-methano-[10]-annulenyl)

Zusammenfassung Kristallisation der Meso-Form der Titelverbindung1 aus Benzol-Pentan in Gegenwart von 5% (+)(R) _p (S) _a (R) _p -1 lieferte Kristalle, deren Struktur in der achiralen Raumgruppe P2₁/a-C _2h ⁵ bestimmt werden konnte: Die Konfiguration (R) _p (S) _p wurde bestätigt, der Torsionswinkel um die 2,2-Bindung beträgt 68.6 bzw. 72.1° (C3-C2-C2-C3 bzw. C1-C2-C2-C1). Die Verkippung der besten Ebenen, definiert durch die Perimeter-C-Atome 3, 4, 5 und 7, 8, 9 (bzw. 3, 4, etc.) beträgt 26.0 bzw. 19.8°. Die Farben der Kristalle der Stereoisomere von1 hängen von den Torsionswinkeln und damit von der Konjugation der -Systeme ab: Meso, monoklin (70.3°): hellgelb; Racemat, opt. inaktiv (56.2°): gelb: Enantiomer des Racemates (34.4°): orange (gemittelte Werte).