Disordered Crystal Structure of the 1:3 Solvated Molecular Ionic Complex of 1,10-Diaza-18-crown-6 with (+)-Tartaric Acid

The disordered crystal structure of the 1:3 solvated molecular ionic complex of 1,10-diaza-18-crown-6 with (+)-tartaric acid [C₁₂H₂₈N₂O₄]²⁺·2C₄H₅O ₆ ^- ·C₄H₆O₆·1.5CH₃OH·1.7H₂O (I) was investigated by XRD analysis. Crystals I are monoclinic: space group P2 ₁, a = 9.662(2), b = 13.618(5), c = 14.316(3) , = 93.97(2)°, Z = 2. Structure I was solved by direct methods and refined by the full-matrix least-squares procedure anisotropically to R = 0.081 for all 3539 unique measured reflections (CAD-4 automatic diffractometer, CuK ). In structure I, the solvated methanol and water molecules are disordered on many sites. The DA18C6 dication is also disordered and has two different asymmetric conformations. The two tartrate anions lie on different sides of the cavity of the DA18C6 dication, whose two NH ₂ ⁺ groups each forms two H-bonds of N–H...O type with each of the tartrate anions. The (+)-tartaric acid molecule and the solvated molecules are not involved in the H-bonds with the DA18C6 dication. The molecular ionic complex I exists in crystal as a complex infinite three-dimensional supramolecular structure.     

Spatial structure of diacetyldihydroungminorine

The structure of diacetyldihydroungminorine, C₂₁H₂₅NO₇ (I), has been determined by the x-ray structural method: diffractometer, CuK radiation, 1278 reflections, R=0.089. An analysis has been made of the conformation of the (I) molecule in comparison with that observed for dihydrolycorine in solution and in the crystalline form. It was shown that the conformations of rings B, C, and D of the (I) molecule in the crystal and of dihydrolycorine in solution are identical. The lack of correspondence of the crystal-solution conformations in dihydrolycorine is connected with an inversion of the unshared electron pair of the nitrogen atom on the formation of a salt — the hydrobromide.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 105–108, January–February, 1992.     

Ritter reactions. X. Structure of a new multicyclic amide-benzene inclusion compound

5H-Dibenzo[a, d]cyclohepten-5-ol1 can undergo Ritter reaction with acetonitrile and sulfuric acid to afford either the acetamide derivative2 or the multicyclic amide3 depending on the conditions used. The X-ray structure of the inclusion compound of3 with benzene is reported here and analysed in structural terms. This material [(C₁₉H₁₈N₂O)–(C₆H₆),Cc,a=10.694(5),b=22.843(5),c=9.901(4) Å,=124.02(2)°,Z=4,R=0.054] has molecules of3 linked by –N–HO=C intermolecular hydrogen bonds to form parallel chains alongc. Additional inter-host stabilisation is achieved by face-face interactions involving one of the two benzo rings of3. A hydrogen atom of the other host benzo group participates in an edge-face interaction with the benzene guest molecule to produce the inclusion compound. Benzenebenzene inter-guest interactions provide a further, but minor, contribution to the net stability of the structure. Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82189 (10 pages).     

Two clathrates of bis(isothiocyanato)tetrakis(4-methylpyridine)magnesium(II) as a host with 4-methylpyridine as a guest

Two clathrate modifications of the title host with 4-methylpyridine (4-CH₃C₅H₄N) as a guest have been determined at –50°C. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · 2/3(4-CH₃C₅H₄N) · 1/3H₂O is trigonal, space group , witha=27.630(7),c=11.219(3) ÅV=7417(4) ų,Z=9,D _calc=1.171 g cm^–3,(CuK )=18.506 cm^–1, finalR=0.064. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · (4-CH₃C₅H₄N) is tetragonal, space group I4_l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D _calc=1.191 g cm^–3, (CuK )=18.200 cm^–1, finalR=0.071.The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.     

13C NMR spectra of a number of penta- and hexacyclic triterpenoids derived from glycyrrhetic acid

The¹³C NMR spectra of 22 derivatives of 18- and 18-glycyrrhetic acids that have been investigated and an assignment of the signals has been made. It has been shown that a modification of the carboxy group of glycyrrhetic acid leads mainly to a change in the chemical shifts of the -, -, and -carbon atoms of ring E. The assignment of a number of signals has been confirmed by the use of the shift reagent Eu(fod)_s. It has been established that the C₂₈ and C₁₆ signals are the most sensitive to a change in the C₁₈ configuration in the spectra of glycyrrhetic acid derivatives.Institute of Chemistry, Bashkir Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 645–653, September–October, 1985.     

Crystalline and molecular structure ofDL-2-amino-4-phosphonobutyric acid monohydrate

The crystalline and molecular structure ofDL-2-amino-4-phosphonobutyric acid monohydrate has been studied by means of x-ray diffraction analysis. The acid molecule exists in a zwitterionic form with a deprotonated PO₃H₂ group. In the crystalline structure there is a branched system of intermolecular hydrogen bonding and the unusual intermolecular bond C–H...O=C forming part of it has been found.Institute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2561–2565, November, 1992.     

Crystal and molecular structures of fluorinated derivatives of C60 fullerene

Two solvates of fluorinated derivatives of C₆₀ fullerene were studied by single-crystal X-ray diffraction analysis. The crystals of fluorinated fullerene solvate C₆₀F₁₈·C₆H₅Me belong to the monoclinic system with the unit cell parameters a = 11.532(2) , b = 21.501(3) , c = 16.261(2) , = 101.798(5)°. The fluorinated fullerene molecule with the approximate symmetry C _3v occupies a general position. The crystals of fluorinated fullerene solvate C₆₀F₄₈·2C₆H₃Me₃ belong to the cubic system (a = 23.138(2) ). The C₆₀F₄₈ molecule occupies the special position with the S ₆ symmetry. The experimental molecular geometry agrees with the results of quantum-chemical calculations.     

Triterpenoide. XIX. 3β‐Hydroxy‐11‐oxo‐18α‐olean‐12‐en‐28‐säure‐methyl­ester und 3,11‐Dioxo‐18α‐olean‐12‐en‐28‐säure‐methyl­ester

The X‐ray crystal structure analyses of 3β‐hydroxy‐11‐oxo‐18α‐olean‐12‐en‐28‐oic acid methyl ester ethanol solvate, C₃₁H₄₈O₄·C₂H₆O, (I), and 3,11‐dioxo‐18α‐olean‐12‐en‐28‐oic acid methyl ester, C₃₁H₄₆O₄, (II), are described. These two compounds differ only in the structure of ring A. In (I), ring A has a chair conformation, while in (II), it has a twisted boat conformation. In both compounds, ring C has a slightly distorted sofa conformation, rings B, D and E are in chair conformations, and rings D and E are trans‐fused. The asymmetric unit of (I) contains one mol­ecule of ethanol linked by hydrogen bonds with two different mol­ecules of (I).     

Interaction of dihydroxy host systems with glycols. A comparative study of the crystal structures of 1:1 molecular complexes of 1,4-butanediol with 2,5-bis(4-chlorophenyl)hydroquinone andtrans-9,10-dihydroxy-9,10-diphenyl-9,10-dihydroanthracene

The title compounds crystallize in space groupC2/c withZ=4; C₁₈H₁₂O₂Cl₂·HO(CH₂)₄OH,a=16.186(3),b=7.626(1),c=16.939(3) Å, =91.32(2)°,R _F =0.048 for 1743 observed MoK reflections; C₂₆H₂₀O₂·HO(CH₂)₄OH,a=11.881(3),b=13.009(4),c=16.689(4) Å, =110.67(2)°,R _F =0.066 for 1783 data points. Both structures feature centrosymmetric hydrogen-bonded (OH)₄ rings formed by molecular components located in special positions. Different packing modes account for the observed conformations (g ⁺ ag ^– andaaa, respectively) of 1,4-butanediol and its possible replacement by 1,2-ethanediol as a guest in the former crystal structure. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82009 (25 pages).Dedicated to Professor H. M. Powell.     

Ferrocene compounds: methyl 1′‐aminoferrocene‐1‐carboxylate

The title compund, [Fe(C₅H₆N)(C₇H₇O₂)], features one strong intermolecular hydrogen bond of the type N—H...O=C [N...O = 3.028 (2) Å] between the amine group and the carbonyl group of a neighbouring molecule, and vice versa, to form a centrosymmetric dimer. Furthermore, the carbonyl group acts as a double H‐atom acceptor in the formation of a second, weaker, hydrogen bond of the type C—H...O=C [C...O = 3.283 (2) Å] with the methyl group of the ester group of a second neighbouring molecule at (x, −y − , z − ). The methyl group also acts as a weak hydrogen‐bond donor, symmetry‐related to the latter described C—H...O=C interaction, to a third molecule at (x, −y − , z + ) to form a two‐dimensional network. The cyclopentadienyl rings of the ferrocene unit are parallel to each other within 0.33 (3)° and show an almost eclipsed 1,1′‐conformation, with a relative twist angle of 9.32 (12)°. The ester group is twisted slightly [11.33 (8)°] relative to the cylopentadienyl plane due to the above‐mentioned intermolecular hydrogen bonds of the carbonyl group. The N atom shows pyramidal coordination geometry, with the sum of the X—N—Y angles being 340 (3)°.     

Tin(IV) complexes ofSchiff bases derived from salicylaldehyde and aminoalcohols

11 and 12 molar reactions of tin(IV) chloride with theSchiff bases, HO–C₆H₄CHNROH [where R=–(CH₂)₂–, –CH₂–, –CH(CH₃)–, –(CH₂)₃–, and –CH(C₂H₅)CH₂–] have been studied in different stoichiometric ratios and derivatives of the type SnCl₄(SBH₂) and SnCl₄(SBH₂)₂ (whereSBH₂ represents theSchiff base molecule) have been isolated. These have been characterised by elemental analysis, conductivity measurements and I.R. spectral studies.     

Triphenylphosphine oxide–3‐chlorobenzoic acid (1/1)

In the title compound, C₁₈H₁₅OP·C₇H₅ClO₂, the tri­phenyl­phosphine oxide molecule forms a single directed hydrogen bond with the 3‐chloro­benzoic acid molecule, with an O⃛O=P distance of 2.607 (2) Å. The C—Cl and C=O bonds adopt a cisoid conformation in the 3‐chloro­benzoic acid molecule.     

Crystal Structure of the Bis(Picrato-O,O")Tetraaquacalcium Complex with 18-Crown-6, [Ca(Pic)2(H2O)4] · 18C6

The crystal structure of the bis(picrato-O,O")tetraaquacalcium complex with 18-crown-6, [Ca(Pic)₂(H₂O)₄] · 18C6 (I), was studied using X-ray diffraction analysis: space group C2/c, a= 20.446 Å, b= 14.985 Å, c= 16.163 Å, = 135. 41°, Z= 4. The structure of Iwas solved by the direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R= 0.047 over all 3044 measured independent reflections (CAD4 automated diffractometer, MoK radiation). In the crystal, Iis not a guest–host complex but exists as individual [Ca(Pic)₂(H₂O)₄] and 18C6 molecules joined by intermolecular hydrogen bonds and van der Waals interactions. The Ca²⁺cation (CN 8) is located on a twofold crystallographic axis, its coordination polyhedron being a distorted square antiprism. The centrosymmetrical 18C6 molecule has a crown conformation with approximate D _3d symmetry and has six neighboring water molecules (three on each side of its mean plane), which form eight hydrogen bonds involving all six O atoms of 18C6.     

6‐Amino‐5,5,7‐tri­cyano‐3,3a,4,5‐tetra­hydro‐2H‐indene‐4‐spiro­cyclo­pentane

The positions of the C=C double bonds in the title compound, C₁₆H₁₆N₄, the subject of some dispute in the literature, have been clearly identified. The cyclo­hexene ring has a distorted half‐chair conformation and the cyclo­pentene and cyclo­pentane rings adopt envelope conformations. The dihedral angles between planar fragments of the cyclo­hexene and cyclo­pentene rings and of the cyclo­hexene and cyclo­pentane rings are 7.5 (1) and 86.98 (9)°, respectively. In the crystal, intermolecular N—H?N hydrogen bonds link the mol­ecules into infinite chains running in the [10] direction.     

Conformational studies of hydantoin‐5‐acetic acid and orotic acid

Hydantoin‐5‐acetic acid [2‐(2,5‐dioxoimidazolidin‐4‐yl)acetic acid] and orotic acid (2,6‐dioxo‐1,2,3,6‐tetrahydropyrimidine‐4‐carboxylic acid) each contain one rigid acceptor–donor–acceptor hydrogen‐bonding site and a flexible side chain, which can adopt different conformations. Since both compounds may be used as coformers for supramolecular complexes, they have been crystallized in order to examine their conformational preferences, giving solvent‐free hydantoin‐5‐acetic acid, C₅H₆N₂O₄, (I), and three crystals containing orotic acid, namely, orotic acid dimethyl sulfoxide monosolvate, C₅H₄N₂O₄·C₂H₆OS, (IIa), dimethylammonium orotate–orotic acid (1/1), C₂H₈N⁺·C₅H₃N₂O₄⁻·C₅H₄N₂O₄, (IIb), and dimethylammonium orotate–orotic acid (3/1), 3C₂H₈N⁺·3C₅H₃N₂O₄⁻·C₅H₄N₂O₄, (IIc). The crystal structure of (I) shows a three‐dimensional network, with the acid function located perpendicular to the ring. Interestingly, the hydroxy O atom acts as an acceptor, even though the carbonyl O atom is not involved in any hydrogen bonds. However, in (IIa), (IIb) and (IIc), the acid functions are only slightly twisted out of the ring planes. All H atoms of the acidic functions are directed away from the rings and, with respect to the carbonyl O atoms, they show an antiperiplanar conformation in (I) and synperiplanar conformations in (IIa), (IIb) and (IIc). Furthermore, in (IIa), (IIb) and (IIc), different conformations of the acid O=C—C—N torsion angle are observed, leading to different hydrogen‐bonding arrangements depending on their conformation and composition.     

Conformational analysis of thiopeptides: (ϕ,ψ) maps of thio‐substituted dipeptides

Noncoded amino acids such as isobutyric acid have been used extensively in the process of drug design and protein engineering. This article focuses on a noncoded amino acid where the oxygen in the peptide unit is replaced with a sp² sulfur. It was hypothesized that the conformational space as well as the conformational preferences of thiopeptides will be more restricted and altered by the bulkier atom with different electrostatic properties. In vacuo conformational minima as well as associated energies for the thio‐substituted alanine dipeptides were calculated at the ab initio HF/6‐31G* level. When the bulkier sulfur atom acts as a hydrogen bond acceptor in the C₅ conformation or in the C$^{\mathrm{axial}}_{7}$ and C$^{\mathrm{equatorial}}_{7}$ conformations, the hydrogen bond lengths are much longer than that of normal peptides. Consequently, the ?, ψ dihedral angles of the C₅, C$^{\mathrm{axial}}_{7}$, and C$^{\mathrm{equatorial}}_{7}$ conformations change to accommodate the longer hydrogen bonds. The thiopeptide group is a poorer hydrogen bond acceptor and a better hydrogen bond donor than the normal peptide group. Therefore, thio‐substitution at the amino terminal leads to disfavoring of the C₇ conformations relative to the C₅ conformations and thio‐substitution at the carboxyl terminal leads to favoring of the C₇ conformations relative to the C₅ conformation. To simulate the conformations in solution, (?,ψ) conformational energy maps were calculated for the glycine and alanine dipeptides at various dielectric constants using the CFF91 force field with our previously derived parameters for the thioamide group. The results show that thio‐substitution does restrict the conformations available to amino acids residues in peptides. Thio substitution at the amino terminal introduces unfavorable interactions near ?=?120 and 120, where there are increased overlaps between S_n?1?H_β, and S_n?1?C_β atoms, respectively. Thio substitution at the carboxyl terminal restricts the conformations near ψ=60, ?60, and 180, which correspond with increase overlaps between S_n?C_β, S_n?H_β′ and S_n?N_n atoms, respectively. The effects of dithio substitutions of either the alanine or the glycine dipeptides are similar to the combined effects of the two single thio substitutions. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1026–1037, 2001     

Inclusion compounds of (±) gossypol. Structure of the gossypol-n-valeric acid (1/2) coordinato-clathrate

The crystal structure of the inclusion compound of gossypol withn-valeric acid as a guest molecule has been determined by X-ray structure analysis. The crystals of C₃₀H₃₀O₈·(C₅H₁₀O₂)₂, are triclinic, space group ,a=6.912(2),b=14.506(3),c=19.387(4) Å, =78.85(2)°, =83.92(3)°, =86.78(3)°V=1895(1) ų,Z=2,D _x=1.267 g cm^–3, (CuK )=0.768 mm^–1,T=292 K. The structure has been solved by direct methods on intensity data collected for a twinned crystal and refined to the finalR value of 0.062 for 1606 observed reflections and 470 refined parameters.Gossypol-n-valeric acid (1/2) coordinato-clathrate is not isostructural with any of the previously investigated gossypol inclusion compounds but shows some structural similarities to gossypol-acetic acid (1/1). The host and one of the carboxylic acid molecules are connected via hydrogen bonds into molecular assemblies of a column type which are further bonded to centrosymmetric dimers of the secondn-valeric acid molecule. In effect, host and guest molecules are assembled into layer-type H-bonded aggregates. Structural features common to gossypol-n-valeric acid (1/2) and other earlier reported gossypol inclusion compounds are discussed.Supplementary Data relevant to this article have been deposited with the British Library under the number SUP 82194 (9 pages)     

6β‐Hydroxy‐5β‐methyl‐20‐oxo‐19‐norpregn‐9(10)‐en‐3β‐yl acetate

In the title compound, C₂₃H₃₄O₄, which is an intermediate in the synthesis of pregnane derivatives with a modified skeleton that show potent abortion‐inducing activity, the conformation of ring B is close to half‐chair due to the presence of both the C=C double bond and the axial 5β‐methyl group. Rings A and C have conformations close to chair, while ring D has a twisted conformation around the bridgehead C—C bond. Molecules are hydrogen bonded via the hydroxyl and acetoxy groups into infinite chains. Quantum‐mechanical ab initio Roothan Hartree–Fock calculations show that crystal packing might be responsible for the low values of the angles between rings A and B, and between ring A and rings C and D, as well as for a different steric position of the methyl ketone side chain compared to the geometry of the free molecule.     

Chemistry of bicymantrenyl

Bicymantrenyl, (CO)₃MnC₅H₄C₅H₄Mn(CO)₃, can be metallated with butyllithium in THF at –60 °C into Cp rings. Quenching with electrophiles (D₂0, I₂, CO₂, and DMF) results in the formation of the corresponding bicymantrenyl derivatives with substituents predominantly at -positions.For Part 1, see Ref. I.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 971–973, April, 1996.     

6β‐Azido‐7α‐hydroxy‐17‐oxo‐5α‐androstan‐3β‐yl acetate

In the title compound, C₂₁H₃₁N₃O₄, a potential inhibitor of aromatase, all rings are fused trans. Rings A, B and C have chair conformations which are slightly flattened. Ring D has a 14α‐envelope conformation. The steroid nucleus has a small twist, as shown by the C19—C10⋯C13—C18 torsion angle of 6.6 (2)°. Ab initio calculations of the equilibrium geometry of the mol­ecule reproduce this small twist, which appears to be due to the steric effect of the 6β‐azide substituent rather than to packing effects.