An X-ray Crystallographic Study of the Related Triazenes, 1,4-Di[(<Emphasis Type="Italic">E</Emphasis>)-2-(2-nitrophenyl)-1-diazenyl]piperazine and Methyl 4-{(E)-2-(4-methylpiperazino)-1-diazenyl}benzoate

Abstract The crystal structures of methyl 4-{(E)-2-(4-methylpiperazino)-1-diazenyl}benzoate (2a) and 1,4-di[(E)-2-(2-nitrophenyl)-1-diazenyl]piperazine (3a) have been determined by single crystal X-ray diffraction analysis. The bis-triazene (3a) adopts an unusual pseudo-boat conformation in the piperazine ring, with a dihedral angle of 52.20(0.06)° between the two planes defined within the piperazine ring. The crystal structures of 2a and 3a are compared with the structure of the triazene (4) and the closely related bis-triazene (5). The piperazine ring of 2a adopts a typical chair conformation, whereas the piperazine ring of 3a adopts an unusual boat conformation. Crystal data: 2a C₁₃H₁₈N₄O₂, monoclinic, space group P2₁ /n, a = 13.849(3) ?, b = 6.577(1) ?, c = 14.904(3) ?, α = 90°, β = 96.098(3)°, γ = 90° and V = 1,349.8(4) ?³, for Z = 4. 3a C₁₆H₁₆N₈O₄, triclinic, space group P-1, a = 7.6066(6) ?, b = 8.3741(7) ?, c = 14.507(1) ?, α = 78.673(1)°, β = 81.877(1)°, γ = 73.445(1)° and V = 865.0(1) ?³, for Z = 2. Index abstract The crystal structures of methyl 4-{(E)-2-(4-methylpiperazino)-1-diazenyl}benzoate (2a) and 1,4-di[(E)-2-(2-nitrophenyl)-1-diazenyl]piperazine (3a) have been determined by single crystal X-ray diffraction analysis.     

Methyl 4-((E)-2-{3-[(3-{ (E)-2-[4-(methoxycarbonyl)phenyl]- 1-diazenyl}-5,5-dimethylhexahydro-1-pyrimidinyl)methyl]-5,5-dimethylhexahydro-1-pyrimidinyl-1-diazenyl) benzoate. X-ray crystal structure

Methyl 4-((E)-2-{3-[(3-{(E)-2-[4-(methoxycarbonyl)phenyl]-1-diazenyl}-5, 5-dimethyl hexahydro-1-pyrimidinyl)methyl]-5, 5- dimethylhexahydro-1- pyrimidinyl}-1- diazenyl) benzoate (1) has been synthesized by reaction of a mixture of formaldehyde and 2,2-dimethyl-1,3-propanediamine with p-methoxycarbonylbenzenediazonium chloride. The crystal structure of 1 has been determined by single crystal X-ray diffraction analysis. The crystals of 1 displayed problems of disorder; the asymmetric unit is built up by two independent molecules, which display disorder within a methoxycarbonyl group. The two independent molecules in the asymmetric unit are very similar, differing only slightly about the mutual orientation of the aryltriazenyl groups. With respect to the N–C–N bridge between the hexahydropyrimidinyl rings, the two equivalent fragments containing the triazene moieties are in a cis orientation. The N–N single bonds, in the range 1.319(4)–1.348(4) Å, and the N=N double bonds, in the range 1.255(5)–1.275(4) Å, indicate significant conjugations within the triazene moieties. All the hexahydropyrimidine six-membered rings adopt a chair conformation as shown by their puckering parameters. The crystal packing is determined only by simple van der Waals interactions. The crystal structure of 1 is compared with the previously reported structure of the unbranched hexahydropyrimidine analogue 2. Crystal data: 1 C29H40N8O4, triclinic, space group P-1, a = 13.9652(2), b = 14.2908(3), c = 16.6129(4) Å, = 97.279(1), = 90.872(1), = 107.385(1), V = 3133.6(1) ų, for Z = 4.     

X-ray crystallographic determination of the structure and conformation of 1,4,4-trimethyltricyclo[5.4.0.03,5]-undec-7-en-9-one and 1,4,4,8-tetramethyltricyclo[5.4.0.03,5]-undec-T-en-9-one

The crystal structure and conformation of 1,4,4-trimethyltricyclo[5.4.0.0^3,5]undec-7-en-9-one (I) and 1,4,4,8-tetramethyltricyclo[5.4.0.0^3,5]undec-7-en-9-one (II) have been determined by X-ray diffraction. In both cases the crystals are orthorhombic, P2₁2₁2₁,a=6.194 (2) (I); 7.499 (2) (II),b=7.486 (3) (I); 12.855 (3) (II),c=26.283 (7) (I); 13.928 (4) (II) Å,Z=4. The structure was solved by direct methods, and refined to anR value of 0.048 for 1534 (I) and 0.054 for 1357 (II) withI>3.0 (I). In both compounds substituted by carbonyl group ring has the distorted³E sofa conformation whereas the second one possesses the slightly deformed^7.10B boat conformation.The nomenclature of IUPAC for the name of compounds in the title is applied. However, for simplicity the numbering of the atoms in the paper follow Fig. 1a and 1b.     

Elastic Anomalies at Charge Density Wave Transitions in TaS3 and NbSe3

Abstract

The temperature dependence of the Young's modulus and internal friction of TaS₃ (orthorhombic) and NbSe₃ have been measured by the vibrating reed technique. There is a large minimum 2%, in the modulus of TaS₃ at the commensurate Peierls distortion (T_c = 222K) and the internal friction increases below T_c(ΔQ^?1 = 5×10^?5), although no critical relaxation effects are observed. On the other hand, a very small minimum, ΔE/E ~ 0.06%, is observed at the upper incommensurate transition in NbSe₃, and a small broad increase (0.03%) at the lower transition. The measurements allow estimates to be made of the stress dependence of the transition temperature and of the electron-phonon coupling constant.     

X-ray crystallographic determination of the structure and conformation of new metabolites from microbial hydroxylation by Absidia blakesleeana ATCC 10148

The crystal structure and conformation of 10R-hydroxy-1,4,4-trimethyltricyclo[5.4.0.0^3.5]undec-7-en-9-one (II) and 10S-hydroxy-1,4,4-trimethyltricyclo[5.4.0.0^3.5]undec-7-en-9-one (III) have been determined by X-ray diffraction. In both cases the crystals were monoclinic, P2₁,a=12.907 (4),b=7.484(3),c=14.179(4) Å,=110.65 (3)°,Z=4, (II);a=16.351 (5),b=7.468 (3),c=20.917 (6) Å,=91.83 (4)°,Z=8 (III). The structure was solved by direct methods, and refined to anR _w value of 0.034 for 2483 (II) and 0.053 for 3810 (III) independent reflections, withI3.0(I). There were two crystallographically independent molecules in the case ofII and four in the case ofIII. In all independent forms of both compounds the ring substituted by a carbonyl group had the distorted³E sofa conformation; whereas the second one possessed the slightly deformed^7.10B boat conformation. The crystal structures ofII andIII are stabilized by two and four intermolecular hydrogen bonds, respectively.The nomenclature of IUPAC was applied for the names of compounds, However, for simplicity, numbering of atoms was according to Figs, 1a and 1b.     

Structures of anti,Z-4,4-dimethyl-3-thiosemicarbazide, syn,E,Z-2,4-dimethyl-3-thiosemicarbazide and syn,E-1-cyclopentano-3-thiosemicarbazone

The structures of three alkyl derivatives of thiosemicarbazide are described: anti,Z-4,4-dimethyl-3-thiosemicarbazide (1), syn,E,Z-2,4-dimethyl-3-thiosemicarbazide (2), and syn,E-1-cyclopentano-3-thiosemicarbazone (3). Crystal data: for 1: triclinic, P-1 (#2), a = 5.802(1)Å, b = 6.935(1)Å, c = 8.104(2)Å, = 78.35(1)°, = 82.13(1)°, = 70.71(1)°, and Z = 2; for 2: orthorhombic, Pbca (#61), a = 9.417(3)Å, b = 8.624(2)Å, c = 15.169(3)Å, and Z = 8; for 3: triclinic, P-1 (#2), a = 6.068(3)Å, b = 8.145(4)Å, c = 8.666(5)Å, = 83.75(4)°, = 86.16(5)°, = 74.07(4)°, and Z = 2. In general, molecules are linked by N–H···S hydrogen bonds with sulfurs accepting two or three hydrogen bonds. Structures 2 and 3, which adopt the syn conformation, form N–H···N intramolecular hydrogen bonds. The solid-state structures are consistent with their infrared and proton nuclear magnetic resonance spectra.     

Structures of Eight Thio(semi)carbazones Derived from 2-Acetylpyrazine, 2-Acetythiazole and Acetophenone

Abstract  The structures of eight related thio(semi)carbazones are described. These are syn,1E-2-acetylpyrazine-3-thiosemicarbazone (1), syn,1E,4Z-2-acetylpyrazine-4-ethyl-3-thiosemicarbazone, (2) and syn,1Z-2-acetylpyrazine-4,4-dimethyl-3-thiosemicarbazone (3), syn,1E,4Z-2-acetylthiazole-4-phenyl-3-thiosemicarbazone (4), syn,1Z-phenyl-4,4-dimethyl-3-thiosemicarbazone (5), syn,1E,4Z-phenyl-4-methyl-3-thiosemicarbazone (6), syn,1E,4Z-phenyl-4-ethyl-3-thiosemicarbazone (7), syn,1E,4Z-2-acetophenone-5-(N-aminothionyl)-3-thiocarbazone (8). Crystal data: for 1: triclinic, P-1, a = 5.4053(10) ?, b = 7.435(3) ?, c = 11.772(4) ?, α = 81.70(3)°, β = 82.59(2)°, γ = 77.38(2)°, and Z = 2: for 2: triclinic, P-1, a = 7.322(3) ?, b = 7.8239(16) ?, c = 9.783(4) ?, α = 87.73(2)°, β = 79.46(3)°, γ = 80.41(2)°, and Z = 2; for 3: orthorhombic, Pnma, a = 13.5210(15) ?, b = 6.6914(5) ?, c = 11.7214(10) ?, and Z = 4; for 4: triclinic, P-1, a = 5.7058(7) ?, b = 9.8776(15) ?, c = 11.869(2) ?, α = 76.389(12)°, β = 86.364(13)°, γ = 88.322(12)°, and Z = 2; for 5: triclinic, P-1, a = 7.5362(3) ?, b = 8.6331(4) ?, c = 9.8753(4) ?, α = 91.401(4)°, β = 102.532(4)°, γ = 110.540(4)°, and Z = 2; for 6: monoclinic, P2(1)/c, a = 10.7178(4) ?, b = 5.5866(2) ?, c = 18.7647(9) ?, β = 104.392(5)°, and Z = 4; for 7: monoclinic, P2(1)/c, a = 8.9557(3) ?, b = 9.7418(4) ?, c = 13.6864(5) ?, β = 94.044(4)°, and Z = 4; for 8: triclinic, P-1, a = 9.8091(5) ?, b = 10.6173(4) ?, c = 16.4691(7) ?, α = 75.540(4)°, β = 80.305(4)°, γ = 65.192(4)°, and Z = 4. Structures 1, 2, 4, 5, 7, and 8 form intramolecular N4–H···N1 hydrogen-bonds. Structures 3 and 5 exist in the tautomeric form in which N1 is protonated. Graphical Abstract  Structures of thio(semi)carbazones were found to fall into two categories: those with intramolecular N4-H…N1 hydrogen-bonds, and those which show a tautomeric form in which N1 is protonated.      

Tris(triphenylphosphine)rhodium cyano and triphenylcyanoborate complexes: Structures and a DFT study

The structures of [Rh(CN)(PPh₃)₃](EtOH) (1), [Rh(NCBPh₃)(PPh₃)₃] (2), and [Rh(CNBPh₃)(PPh₃)₃] (3) are reported together with a density functional theory (DFT) study of the model compounds [Rh(NCBH₃)(PH₃)₃] and [Rh(CNBH₃)(PH₃)₃]. Compound 1 crystallizes in space group Pc with a = 10.4798(15) Å, b = 12.5410(18) Å, c = 19.974(3) Å and = 112.215(6)°; compound 2 crystallizes in space group with a = 12.929(2) Å, b = 14.362(2) Å, c = 17.575(3) Å and = 92.544(3)°, = 90.214(3)°, = 113.831(3)°; compound 3 crystallizes in space group with a = 12.915(2), b = 14.296(2), c = 17.664(3) Å and = 92.469(3)°, = 90.088(3)°, = 113.768(3)°. All three complexes show slight tetrahedral distortion from ideal square planar geometry (largest for 1). Differences in the reactivity and stability of 2 and 3 are interpreted according to the results of a density functional theory study.     

Theoretical Design Study on the Electronic Structures and Phosphorescent Properties of Four Iridium(III) Complexes

The geometry structures, electronic structures, absorption, and phosphorescent properties of four Ir(III) complexes have been investigated using the density functional method. Calculations of ionization potential (IP) and electron affinity (EA) were used to evaluate the injection abilities of holes and electrons into these complexes. The result also indicates that the –CF₃ substituent group on the ligand not only change the character of transition but affect the rate and balance of charge transfer. The lowest energy absorption wavelengths are located at 428 nm for 1a, 446 nm for 1b, 385 nm for 2a, and 399 nm for 2b, respectively, in good agreement with the energy gap (ΔE_L-H) trend because the HOMO–LUMO transition configurations are predominantly responsible for the S₀→S₁ transition. 2b has the 433 nm blue emission, which might be a potential candidate for blue emitters in phosphorescent dopant emitters in organic light emitting diodes (OLEDs). The study could provide constructive information for designing novel OLEDs materials in the future.

[Supplemental materials are available for this article. Go to the publisher's online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.]     

Synthesis and Structural Characterization of Hydrazine Bridged Imidazole and its Fumarate Salt

Abstract  

Hydrazine bridged imidazole (1) and its fumarate salt (2) have been synthesized and structurally characterized. Hydrazine bridged imidazole (1) crystallizes in the monoclinic, space group P2(1)/n, with a = 12.809(7) ?, b = 5.102(3) ?, c = 14.401(8) ?, β = 96.859(10)°, V = 934.3(9) ?³, Z = 2. In 1, the two imidazolyl rings are located anti-parallely above and below the benzene planes, respectively. This arrangement leads the imidazolyl rings to be in the trans conformation. In addition at each C=N bond, the larger groups linked to C and N atoms are located in the same side of the double bond, thus in the solid state the conformation of the bis-imidazole (1) is E, E.     

Structures of Three Chalcones Derived from 6-Methoxy-2-naphthaldehyde

Abstract  In the molecular structures of three new structurally related chalcone derivatives, namely (2E)-1-(2-hydroxyphenyl)-3-(6-methoxy-2-naphthyl)prop-2-en-1-one, C₂₀H₁₆O₃, I, (2E)-1-(2-chloropyridin-4-yl)-3-(6-methoxy-2-naphthyl)prop-2-en-1-one, C₁₉H₁₄ClNO₂, II, and (2E)-3-(6-methoxy-2-naphthyl)-1-pyridin-4-ylprop-2-en-1-one, III, C₁₉H₁₅NO₂, the configuration of the keto group is syn with respect to the olefinic double bond. In all three structures the molecules pack with weak intermolecular C–H···O interactions utilizing both the methoxy and keto oxygen’s in I, the methoxy oxygen in II and the keto oxygen in III. These interactions link the molecules into chains diagonally along the (011) plane of the unit cell in I and III and along the (010) plane in II. The dihedral angle between the phenyl and 2-napthyl rings in I is 31.7(3)°. In II and III the dihedral angle between the pyridyl and 2-naphthyl rings is 14.4(9)° and 1.8(9)°, respectively. C–H···O hydrogen bonding interactions influence these twist angles of these rings in I–III while weak π–π stacking interactions between naphthyl rings in I and III and also between pyridyl and naphthyl rings in II help stabilize crystal packing. [I: P2 ₁ /c, a = 7.6635(4) ?, b = 11.8047(6) ?, c = 16.7584(7) ?, β = 99.271(5)°, V = 1496.25(13) ?³; II: Pbca, a = 14.1424(4) ?, b = 6.0957(2) ?, c = 33.1458(11) ?, V = 2857.43(16) ?³; III: P2 ₁ /c, a = 11.5155(4) ?, b = 6.0020(2) ?, c = 22.4645(8) ?, β = 103.002(4)°, V = 1512.85(9) ?³]. Index Abstract  Crystal structures from three Chalcones derived from 6-methoxy-2-naphthaldehyde are reported and their geometric and packing parameters described.     

Crystal Structure and Hirshfeld Surface Analysis of Bis(3-thienoyl) Disulfide

The spectroscopic characterization (¹H, ¹³C{¹H} NMR, UV–Vis) and single-crystal X-ray diffraction (scXRD) analysis accomplished by inspection of the Hirshfeld surface of bis(3-thienoyl) disulfide (1) is described. The title compound 1 crystallizes in the monoclinic space group P2₁/n. The unit cell parameters are a?=?7.9959(3) Å, b?=?6.4348(3) Å, c?=?22.4924(9) Å, β?=?100.108(4)°, V?=?1139.32(8) ų, Z?=?4, R_gt(F)?=?0.0278, wR_ref(F²)?=?0.0667. The packing of 1 is dominated by S?O and S?S interactions, giving a 2D layer structure parallel to (101). The X‐ray crystal structure analysis revealed the packing of 1 is dominated by S?O and S?S interactions, giving a 2D layer structure parallel to (101). The intermolecular interactions in 1 were analyzed using the Hirshfeld surface method including 2D fingerprint plots and enrichment ratios (E), which shows that the most favored intermolecular contacts are the O?H and C?S indicated by E values above 1.30. The interaction energies between molecular pairs revealed the importance of the weak O?H and C?S interactions in stabilizing the molecular structure of 1.

Graphic Abstract

Single crystal X-ray structure analysis, DFT calculations and Hirshfeld surface analysis to identify intermolecular interactions within the solid state structure of bis(3-thienoyl) disulfide (1).

     

Absolute structure of (11E, 1S, 3S, 4R, 7S, 8R, 14S)-3,7-diiodo-4,8-epoxy-euniolide

3,7-Diiodo-4,8-epoxy-euniolide (2) was synthesized from euniolide (1) by the addition reaction of iodine in the presence of triphenylphosphine in CH₂Cl₂. The absolute structure of 2 was unambiguously determined by a combination of ¹H and ¹³C NMR, HREI mass spectroscopy, and x-ray single crystal analysis as (11E, 1S, 3S, 4R, 7S, 8R, 14S)-3,7-diiodo-4,8-epoxy-cembra-11,15-dien-16,14-olide. X-ray crystallographic data for 2: Orthorhombic P2₁2₁2₁ (#19), a = 10.9688(7), b = 11.3909(8), c = 16.885(1) Å, _calcd = 1.795 g cm^–3, and for Z = 4.     

Gap Reduction of C60 and C70 at High Pressure

Abstract

The absorption spectra of the C₆₀ and C₇₀ are measured at pressures up to 19 GPa. The pressure dependence of the fundamental absorption edge position E(P) is determined for both materials. The initial value of dE/dP=?0.15 eV/GPa for the stronger-absorption region of C₆₀ decreases up to ?0.019 eV/GPa at 12 GPa. The weaker-absorption region located near the fundamental absorption edge shifts slower dE/dP=?0.05 eV/GPa. For the C₇₀ the initial value of dE/dP=?0.1 eV/GPa decreases up to ?0.029 eV/GPa at 10 GPa. All pressure induced changes are reversible in this pressure range.     

Crystal and molecular structure of acetamidrazone derivatives

N ¹-acetylacetamidrazones and N ¹-benzoylacetamidrazones (1a–d) were characterized by ¹H and ¹³C NMR spectroscopy. The actual tautomeric form present has been shown to be the amide hydrazone. NMR spectra of N ¹-acetylacetamidrazones (1a,b) showed the existence of Z and E isomers in solution, while N ¹-benzoylacetamidrazones (1c,d) were present as Z isomers. The crystal structures of the amidrazones have been determined at 173 and 293 K, respectively. The amidrazones 1c and 1d crystallize in the monoclinic system: in particular for 1c space group P2₁/c, with a = 11.016(5), b = 20.594(14), c = 13.657(7) Å = 98.29(3)° V = 3066(3) ų and D _c = 1.243 g/cm³ for Z = 4; for 1d space group P2₁/a, with a = 9.410(5), b = 10.449(3), c = 14.295(11) Å = 101.04(5)° V = 1380(1) ų and D _c = 1.220 g/cm³ for Z = 4. The X-ray diffraction analysis carried out on 1c has shown the presence of three molecules in the asymmetric unit which differ for the orientation of the phenyl ring.     

Adsorption of Carboxylic Acids by Diethylenetriamine Intercalation Compound of α-Zr(HPO4)2 · H2O

Abstract

Two kinds of diethylenetriamine (2E3A) intercalation compounds of α-zirconium phosphate with different interlayer distances could be obtained by regulating the reaction time and temperature. Phase I (d = 10.2 Å) slowly transforms to Phase II(d = 15. 8 Å) with transformation enthalpy of 30 kJ-mol^?1 in 2E3A aqueous solution. The conformation of 2E3A in Phase I and Phase II were confirmed to be bent and all trans (straight) forms by³¹P MAS NMR and XRD measurements. Two phases have different adsorption behavior for gaseous carboxylic acids. Phase II can adsorb considerable amount of carboxylic acids whereas Phase I adsorb a little.     

Synthesis,spectral, X-ray diffraction and DFT studies on 1-(2-methyl-2-propenyl)-3-(2,3,4,5,6-pentamethylbenzyl)benzimidazolium chloride hydrate

A new benzimidazole based N-heterocyclic carbene (NHC) salt (1) was synthesized by the reaction of benzimidazole precursor with alkyl halide. The structure of 1 was determined by elemental analysis, FT-IR, ¹H NMR and ¹³C NMR spectroscopy tecniques and X-ray crystallography. The compound crystallized in the triclinic space group P-1 with two molecules in the unit cell. The optimization of 1 was firstly performed at B3LYP/6-311G++(d,p) level, then the theoretical spectral studies performed and compared with the experimental values. Besides the frontier molecular orbital energies and chemical reactivity analysis of 1, together with the electrostatic potential and molecular electrostatic potential analyses were performed at the same level of theory.     

Low Temperature X-ray Structures of Two Crystalline Forms (I) and (II) of the Pyrimidine Derivative and Sodium Channel Blocker BW1003C87: 5-(2,3,5-Trichlorophenyl)-2,4-diaminopyrimidine

Abstract The X-ray crystal structures of two crystalline forms of 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine, C₁₀H₇Cl₃N₄ (code name BW1003C87) (I) and (II), have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are centrosymmetric, with structure (I) in the triclinic space group P unit cell a = 6.4870(10), b = 9.216(2), c = 12.016(2) ?, α = 75.78(3)°, β = 89.95(3)°, γ = 83.45(3)°, V = 691.5(2) ?³, Z = 2 and density (calculated) = 1.544 Mg/m3; and (II) in the monoclinic space group P2₁/c, unit cell a = 12.000(2), b = 7.518(2), c = 13.450(3) ?, β = 97.87(3)°, V = 1202.0(5) ?³, Z = 4, Density (calculated) = 1.600 Mg/m3. Structure (I) includes a solvated CH₃OH in the lattice. Final R indices [I > 2sigma(I)] are R1 = 0.0427, wR2 = 0.1075 for (I) and R1 = 0.0487, wR2 = 0.1222 for (II). R indices (all data) are R1 = 0.0470, wR2 = 0.1118 for (I) and R1 = 0.0623, wR2 = 0.1299 for (II). 5-Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. Both lamotrigine and 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine (code name BW1003C87), the subject of the present study, are anticonvulsant as well as neuroprotective in models of brain ischaemia and in a model of white matter ischaemia. BW1003C87 is a sodium channel blocker which also reduces the release of the neurotransmitter glutamate. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this drug family and their biological activities. Index Abstract Rex A. Palmer, Brian S. Potter, Michael J Leach and Babur Z. Chowdhry 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine occurs in two crystalline forms whose X-ray structures are described here. The molecular conformations in (I) and (II) are quite distinct as illustrated, the ring linkage torsion angle differing by 23.5 deg. (I) has a methanol solvate molecule in the lattice.      

Crystal structure of phenyl-substituted cyclopentenes

The crystal structures of two stereoisomers of tetraphenyl- and pentaphenyl-substituted cyclopentenes 1 and 2 have been determined by X-ray analysis. An envelope conformation ¹E has been ascertained for the cis isomer 1a, whereas the cis, cis isomer 2a, which crystallizes in two different space groups, P1¯ and P2₁/n, displays a twisted ²T₁ conformation. The phenyl substituents are all tilted with respect to the cyclopentene ring in both structures. Compound 1a crystallizes in the space group P2₁/a with a = 18.553(3), b = 6.006(2), c = 19.355(5), = 102.67(4)°, and V = 2104.2(g) ų for Z = 4; compound 2a ^I crystallizes in P2₁/n with a = 10.064(2), b = 20.756(5), c = 12.245(3) Å, = 95.21(2)°, and V = 2547(1) ų for Z = 4; compound 2aII crystallizes in P1¯ with a = 10.117(3), b = 11.750(2), c = 12.359(2) Å, = 111.25(2), = 94.84(2), = 108.78(2)°, and V = 1262.3(6) ų for Z = 2.