Synthesis and crystal structure of 1-acetyl-3-bromo-3-phenylazetidine and 1-phenyl-2-(N-acetyl-N-formyl)-aminoethanone

1-Acetyl-3-bromo-3-phenylazetidine (1), C₁₁H₁₂BrNO, has been synthesized and characterized by spectroscopic methods and single crystal X-ray analysis. It crystallizes in the space group P2 ₁/c with a = 8.633(1), b = 7.461(1), c = 17.204(1) Å, = 98.403(7)°, V = 1096.2(2) ų, Z = 4, D _calc = 1.540 g cm^–3. The azetidine ring is nearly planar since the four atoms are within ±0.039(5) Å of the mean square plane calculated for the heterocycle. The attempt to obtain a highly strained 2-azetine derivative from the above compound gave, surprisingly, 1-phenyl-2-(N-acetyl-N-formyl)-aminoethanone (2), C₁₁H₁₁NO₃. This compound has been also characterized by spectroscopic methods and single crystal X-ray analysis. It crystallizes in the space group P2₁2₁2₁, with a = 5.4719(3), b = 8.3205(6), c = 23.298(3) Å, V = 1060.7(2) ų, Z = 4, D _calc = 1.286 g cm^–3. The aminoethanone residue is in a near planar conformation where the torsion angles are 7(2)° for N–C–C–=O and –173(2)° for N–C–C–C(Ph).     

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.     

The structure of nitrocubane: the last in the series of nitrocubanes

The structure of nitrocubane, C₈H₇NO₂, 1, reported herein, is the last to be reported in a series of nitrocubanes, ranging from mono- to octanitrocubane. Compound 1 crystallizes in the orthorhombic space group Pnma with cell dimensions a = 17.507(5), b = 6.584(2), and c = 5.832(2) Å and Z = 4. Thus the nitrocubane molecule possesses a crystallographically imposed mirror plane. Since the nitro group is in the mirror plane, it is coplanar with the C1–C6 bond in the cubane skeleton. As has been found previously, the C1–C6 bond in the cubane skeleton that is coplanar to its attached nitro groups is shortened (1.533(4) compared to an average value of 1.543(2) Å for all other cubane C–C bonds). In addition the single substitution of the nitro group into the cubane skeleton causes a tetrahedral distortion which is exhibited by alternating C–C–C angles which are greater than and less than 90°.     

Structure of adamantan-1-ammonium 1-adamantanecarboxylate

Adamantan-1-ammonium 1-adamantanecarboxylate, C₂₁H₃₃NO₂ (I) is a novel dispiro-type compound. Aminoadamantane derivatives, in which the spiro carbon atoms are part of heterocyclic rings, are of potential interest as biological active substances and antiviral agents. Complex (I) crystallizes in the centrosymmetric space group C2/c (No. 15) with eight molecules in the unit cell with a = 25.227(4), b = 6.527(1), c = 22.489(4) Å, and = 90.75(1)°. The two spiro units are a 1-adamantylammonium cation and a 1-adamantane carbonyloxy anion. The complex units are stabilized by a network of intermolecular carbonyloxy-to-amine hydrogen bonding and van der Waals cohesive forces. Germane bond lengths are: C—N = 1.479(9) and C—O (mean) = 1.25(2) Å.     

Crystal structure of the keto-enamine form of (+) (1S,2S)-2-(2-hydroxybenzylidene)amine-1-phenyl-1,3-propanediol

The title compound crystallizes in the orthorhombic space group P2₁2₁2₁, withZ=4,a=6.068(1)Å,b=10.922(1)Å, andc=21.713(2)Å. The compound is the chiral ligand of a copper complex used as an enantioselective catalyst. It crystallizes from methanol in the keto-enamine form, though the enol-imine isomer predominates in the solution. Most N-salicylideneamines studied by X-ray are enol-imines. The two tautomeric forms may interchange through anintramolecular hydrogen bond and the distances between non-H atoms in the resulting cyclic –O–H...N=C–C=C- or –C=O...H–N–C=C- fragment may be misleading, so that H atom position is the crucial factor for determination of the proper tautomeric form.     

X-ray crystal structure of 2,5-dioxo-4-imidazolidineethanesulfonamide, C5H9N3O4S

The crystal structure of 2,5-dioxo-4-imidazolidineethanesulfonamide or homocysteine sulfonamide hydantoin, C₅H₉N₃O₄S (1) was obtained by single-crystal X-ray diffraction. Crystallization of 1 occurs in the centrosymmetric monoclinic space group C2/c (No. 15) with a = 15.653(2), b = 9.6489(10), c = 11.066(2) Å, = 94.64(2), and Z = 8. Molecules are in an extended structure with a C–C–C–S torsion angle of –174.2(1). The imidazolidinedione ring is planar and the sulfonamide group has a distorted tetrahedral geometry. A three-dimensional network of intermolecular hydrogen bonding occurs within the crystal lattice involving both imidazolidinedione and sulfonamide functional groups.     

Synthesis and X-ray structure analysis of benzoic acid [1-(6-methyl-2,4-dioxo-3,4-dihydro-2H-pyran-3-yl)eth-(E)-ylidene]-hydrazide with a water molecule (C15H14N2O4?H2O)

The crystal structure of the title compound has been determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P2₁/n with cell parameters a = 7.097(1) Å, b = 19.257(1) Å, c = 10.893(1) Å, = 106.17(2), V = 1429.8(3) ų and Z = 4. The final reliability index is 0.059 for 2419 observed reflections. The molecule comprises of two six- membered rings which are abridged together through a network of C–N, N–N and C–N bonds. There are three keto functional groups and two methyl groups at various locations of the molecule. The C9 atom of methyl group and O2 of the keto group are deviated significantly from the mean plane of the molecule. Both the six-membered rings are planar and it is evident from the magnitude of their exocyclic torsion angles. The molecular structure is stabilized by few intra and intermolecular hydrogen bonds.     

First example of cocrystals of polymorphic maleic hydrazide

The first cocrystals of polymorphic maleic hydrazide with 3-methyluracil have been studied by X-ray diffraction methods. They crystallize in the orthorhombic system, space group Pmcn, a = 6.440 (1) Å, b = 6.974 (1) Å, c = 22.829 (11) Å, V = 1025.3 (5) ų, Z = 4. The asymmetric unit contains one molecule of each compound. Planar ribbons of the (1:1) molecular complex are obtained through the formation of O–H···O and O–H···N intermolecular hydrogen bonds, just forming a well-known R² ₂(8) supramolecular synthon. Supramolecular assemblies are then formed by weak C–H···O and C–H···N hydrogen bonds through adjacent antiparallel ribbons.     

Planarity of <Emphasis Type="Italic">N</Emphasis>′-(amino-2-pyridylmethylene)-hydrazide carbodithioic acid frame and crystal structure of its methyl ester dihydrate

The title compound exists in a dipolar form both in the solvent-free and in the dihydrate crystal. Unit cell dimensions: 23.303(5), 7.3100(10), 15.030(3) Å, β = 101.78(3)^∘; space group C2/c (monoclinic) with Z = 8. The molecule is flat due to extended conjugation in the central N=C(pyr)–N(3)H–N=C–S– fragment and three assisted intramolecular hydrogen bonds, one of them between the pyridine N atom (acceptor) and the N(3)H amine group as a hydrogen bond donor. As a result the molecule adopts an antiperiplanar conformation along the N–N bond and synperiplanar conformation along the neighbouring N–C bonds. Presence of two water molecules results in a very extensive network of intermolecular hydrogen bonds (eight) as compared with the crystal structure of the anhydrous compound.     

Intramolecular hydrogen bonding and tautomerism in N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine

N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine (C₁₆H₁₂N₂O) was studied by elemental analysis, IR, ¹H NMR, and UV–visible techniques and X-ray diffraction methods. The UV–visible spectrum of the compound was investigated in solutions effect polarity. The polarity of the some solvents was modifierly the additional (CF₃COOH) and [(C₂H₅)₃N]. The compound is in tautomeric equilibrium (phenol-imine O–H···N and keto-amine O···H–N forms) in polar and nonpolar solvents. The keto-amine form is observed in basic solutions of DMSO, ethanol, chloroform, benzene, cyclohexane, and in acidic solutions of chloroform and benzene, but not in acidic solutions of DMSO and ethanol. The compound crystallizes in the monoclinic, space group P2₁/a with a = 7.010(5) Å, b = 13.669(4) Å, c = 12.764(4) Å, = 101.23(4)°, V = 1199.6(10) ų, Z = 4, D _c = 1.375 g/cm³, (Mo K) = 0.088 mm^–1, R = 0.045 for 1658 reflections [I > 2(I)]. The title compound is not planar two Schiff base moieties A [C1–C11, O1] and B [N1, C12, C13, N2, C14, C15, C16] are inclined at an angle of 27.4(1)° reflecting mainly the twist about C12–N1 [C11–C12–N1–C13, 29.7(2)°]. There is a strong intramolecular hydrogen bond (O–H···N) of 2.529(2) Å.     

Effect of boron on the crystallization of amorphous Si–(B–)C–N polymer-derived ceramics

Amorphous Si–(B–)C–N polymer-derived ceramics (PDCs) with a boron content ranging from 0 to 8.3 at.%, were synthesized by thermolysis of boron-modified poly(methylvinylsilazane). Correlation of the boron content and the thermal stability of these materials in the course of annealing were investigated using high temperature thermal gravimetric analysis (HT-TGA). Furthermore, the initial crystallization of the as-thermolyzed amorphous ceramics was studied by X-ray diffraction (XRD) measurements. The increase of boron content promotes the crystallization of SiC, and inhibits the crystallization of Si₃N₄. Moreover, the ratio of α-Si₃N₄/β-Si₃N₄ in crystalline ceramic decreases with increasing boron content. Thermodynamic modeling proves the influence of boron content on driving force for crystallization. The available thermodynamic model of amorphous Si–C–N domains, nano-crystalline silicon nitride, and nano-crystalline silicon carbide treated as the separated phases has been used to interpret these results.     

Crystal and molecular structure of 1-chloro-1,2-benziodoxolin-3(1H)-one·tetra-n-butylammonium chloride

The title compound,6, a novel 11 complex of 1-chloro-1,2-benziodoxolin-3(1H)-one (5) andtetra-n-butylammonium chloride, was prepared from tetra-n-butylammoniumo-iodoxybenzoate (7) and acetyl chloride. A single crystal of6 was subjected to X-ray analysis: triclinic, space group a=10.239(2),b=11.518(2),c=11.523(3)Å; =73.20(2); =87.85(2), =87.72(2)°; R1=0.0326. The most notable structural feature of crystalline6 is the existence of a secondary bond [I· ·Cl(2), 2.943(1)Å] between the chloride ion and the iodine atom of the chlorobenziodoxolinone moiety. Further coordination at iodine includes three primary bonds: I–C [2.115(4) Å], I–O [2.145(3) Å], I–Cl(1) [2.454(1) Å]. The entire 1-chlorobenziodoxolinone-chloride sub-structure is planar and exhibits iodine-centered bond angles of 78.8(1)° [C–I–O], 92.0(1)° [C–I–Cl(1)], 97.6(1)° [Cl(2)–I–O] and 91.6(1)° [Cl(2)–I–Cl(1)]. The unit cell of6 contains two loosely packed formula units. The chlorobenziodoxolinone-chloride sub-structures occupy a common plane and exhibit a centrosymmetric relationship, while the tetra-n-butylammonium ions are situated one above and one below the plane. Bonding at the iodine atom in6 is more consistent with a 10-I-3 species electrostatically associated with the chloride ion than a 12-I-4 species such as the tetrachloroiodate ion.     

Crystallographic and conformational analysis of 2-methyl-3-(2-nitro-phenyl)-4-phenyl-[1,2,4]oxadiazolidin-5-one

Molecular and crystal structure of 2-methyl-3-(2-nitro-phenyl)-4-phenyl-[1,2,4]oxadiazolidin-5-one, C₁₅H₁₃N₃O₄, have been determined by single crystal X-ray diffraction study. The title compound is monoclinic, with a = 10.0313(8) Å, b = 9.0372(5) Å, c = 15.5964(14) Å, β = 96.926(7)^∘, Z = 4, D_x = 1.42 g/cm³, μ (Mo-K_α) = 0.105 mm⁻¹, and space group is P 2₁/c. The structure was solved by direct methods and refined to a final R = 0.036 for 1894 reflections with I > 4σ (I). The crystal structure is stabilized by C–H⋅sO type inter-molecular, C–H⋅sN and C–H⋅sO type intra-molecular, π–π stacking and edge to face (C–H⋅s π-ring) interactions. To enlighten conformational flexibility of the title molecule, selected two torsion angles are varied from −180^∘ to +180^∘ in every 10^∘ separetely and then molecular energy profile is calculated and construed.     

syn,E-1-cyclopentano-4-ethyl-3-thiosemicarbazone and syn,E-1-cyclopentano-4-phenyl-3-thiosemicarbazone

The structures of two thiosemicarbazones are described: syn,E-1-cyclopentano-4-ethyl-3-thiosemicarbazone (1) and syn,E-1-cyclopentano-4-phenyl-3-thiosemicarbazone (2). Crystal data: for 1: tetragonal, P4₃ (#78), a = b = 8.922(7) Å, c = 12.899(13) Å, and Z = 4; for 2: monoclinic a = 15.163(18) Å, b = 7.482(5) Å, c = 12.467(15) Å, = 119.04(7)°, and Z = 4. In 1, molecules are linked by hydrogen-bonding into infinite chains with non-planar 9-ring subunits in which thioamides interact with the H—N—C—N—N groups of neighbors. Thioamide groups in 2 form dimers linked by N—B···HS hydrogen-bonds with a planar 8-ring as in solid state structures of carboxylic acids. The semicarbazide syn conformation fosters formation of N—H···N intramolecular hydrogen-bonding in each structure. The solid state structures are consistent with their infrared and proton nuclear magnetic resonance spectra.     

Solid-state structure of a 1:1 adduct of 2-<Emphasis Type="Italic">t</Emphasis>-butylphenol and 3-<Emphasis Type="Italic">t</Emphasis>-butylsalicylaldehyde

The co-crystal structure of 2-t-butylphenol with 3-t-butylsalicylaldehyde (1) was obtained by single-crystal X-ray diffraction. 2-t-Butylphenol was co-crystallized with 1 equivalent of 3-t-butylsalicylaldehyde. The phase crystallizes in the monoclinic system with P2₁/c space group. The unit cell dimensions are a = 12.351(3) Å, b = 15.253(3) Å, c = 10.377(2) Å, β = 97.58(3)^∘, V = 1937.8(7) ų and Z = 4. The structure of the crystal layered by nonpolar group includes strong intramolecular and weak intermolecular hydrogen bonds. The aldehyde oxygen O2 accepts a three-centered bond through intramolecular O1–H1A⋅sO2 and intermolecular O3–H3A⋅sO2 interactions. In addition, the crystal consists of right-handed helical (P) and left-handed helical (M) chains linked by hydrogen bonding.     

Helical chirality of 1-phenacyl-1,10-phenanthrolinium bromides

Evidence for non-coplanarity of the pyridine and pyridinium rings in a series of 1-phenacyl-1,10-phenanthrolinium bromides was gleaned from ¹H-NMR data recorded in DMSO-d ₆ solution. The X-ray structure of 1-(4-chlorophenacyl)-1,10-phenanthrolinium bromide, as representative of this series, was determined in order to establish whether such a molecular distortion occurs in the solid state. The title compound crystallizes in the space group C2/c as a sesquihydrate of formula C₂₀H₁₄BrClN₂O·1.5H₂O with a = 35.7348(3) Å, b = 5.3468(1) Å, c = 21.7312(2) Å, = 116.4076(4)° and Z = 8. In the crystal, the helical chirality is manifested as a pronounced twist in the phenanthrolinium moiety, with the pyridine and pyridinium rings inclined at 6.8(2)°. This distortion is attributed to intramolecular hydrogen bonding of type C–H···N involving the methylene group and the uncharged nitrogen atom of the phenanthrolinium moiety. In the crystal, the cations surround an intricate array of water molecules and bromide ions held together by O–H···Br^– hydrogen bonds and comprising infinite chains ···Br^–···H–O–H···Br^–···, cross-linked by water molecules.     

Interfacial structure of oxidized inner pores in precursor-derived Si–C–N ceramics

Inner pore channels were commonly found in precursor-derived Si–C–N ceramics. After annealing in air at 1420 °C, their oxidation structures were investigated by analytical TEM. A carbon-rich ring was frequently observed under the silica layer inside the pore channels, which consisted of graphite-like clusters in size of 20–30 nm. Origin of such interfacial structure is due to the excessive free-carbon in the amorphous Si–C–N matrix that had survived the oxidation process. This graphitic interface could further improve the oxidation resistance of the SiO₂ over-layer. This novel interfacial structure was also found by annealing in N₂, reaffirming the effect of composition of Si–C–N matrix.     

Crystal structure of enantiomeric 3-amino-6,7-dihydro-6-hydroxy-5H-1,2,4-triazolo [3,4-b] 1,3-thiazine

The crystals of C₅H₈N₄OS are orthorhombic, space group P2₁2₁2₁ (Z=4),a=5.601(1),b=10.224(3), andc=12.233(2) Å. 1,2,4-Triazole ring is approximately planar while 1,3-thiazine ring adopts a C(5)-sofa conformation flattened at the N–C–S end with axial hydroxy group at the opposite side of the ring. The three intermolecular hydrogen bonds, N(3)...O(8), N(3)...N(2), and O(8)...N(1) form a three-dimensional hydrogen bonds network in the crystal. The structure is the first 5H-1,2,4-triazolo [3,4-b] 1,3-thiazine reported in the literature. It shows less aromatic character and smaller delocalization of electrons of the triazole ring than those in known analogs with [5,1-b] junction.     

Two-dimensional crown ether complex. Synthesis and crystal structure of [Na(N15C5)]<Subscript>2</Subscript>[Cu(mnt)<Subscript>2</Subscript>]

A novel crown ether complex [Na(N15C5)]₂[Cu(mnt)₂] (1) (where N15C5 = 2,3-naphtho-15-crown-5 and mnt = maleonitriledithiolate, [C₂S₂(CN)₂]^2–) was synthesized and characterized by elemental analysis, FT-IR spectra, UV-visible spectra and single crystal X-ray diffraction. Structural analysis reveals that the complex 1 consists of two [Na(N15C5)]⁺ complex cations and one [Cu(mnt)₂]^2– complex anion and the complex molecules are assembled into a novel 2D network by Na–N interactions. In the network, there are 34-member macrocycles formed by four sodium ions of complex cations and four complex anions through Na–N bonds. In each macrocycle, – stacking interactions occurred between two parallel naphthylene moieties of N15C5. It is interesting that the 2D network displays an open-capped wave-like sheet viewed along the crystallographic a axis.     

The role of hydrogen bonding in pseudo-macrocyclic ring formation in 2,6-dimethyl-1,3,5,7-cyclooctatetraene 1,3,5,7-tetracarboxylic acid monohydrate

2,6-Dimethyl-1,3,5,7-cyclooctatetraene-1,3,5,7-tetracarboxylic acid 3, C₁₄H₁₄O₉, was prepared by thermolysis of the corresponding semibullvalene and characterized by spectroscopic and single-crystal X-ray diffraction studies. The monohydrate of 3 crystallizes in the tetrahedral space group P-4n2, a = 11.0924(3) Å, c = 12.6799(5) Å, V = 1560.15(9) ų, Z = 4. The cyclooctatetraene ring adopts a tub-shaped conformation with a crystallograpically imposed twofold rotational symmetry, and is composed of localized C=C double bonds in the 1,3,5, and 7 positions with an average interatomic distance of 1.327 (5) Å and C–C single bonds with an average interatomic distance of 1.489(5) Å. The average C=C–C angle in the ring is 122.6(3)°. Each symmetry generated eight-membered ring contains four carboxyl groups, two of which are coplanar with the methyl groups across the C=C ring atoms. However, across the C–C bonds the carboxyl groups and the methyl groups show a torsion angle of 64.3(4)°. The presence of a water molecule in the crystal lattice generates a three-dimensional network of close hydrogen bondings between water and the carboxyl groups of multiple rings. This creates a network of orthogonal 10-membered rings between the 8-membered rings. Two given cyclooctatetraene rings are intermolecularly hydrogen bonded not only directly through their carboxyl groups but also via a bridging water molecule. This effect is rare in polycarboxylic acids and their monohydrates which bond only with water or among themselves.