N-Methyl-4-(4-nitrophenyl)-N-nitroso-1,3-thiazol-2-amine

2017

The title compound, C10H8N4O3S, is almost planar [dihedral angle between the rings = 2.2 (2)°; r.m.s. deviation for the non-H atoms = 0.050 Å]. In the crystal, C—H...O and C—H...N hydrogen bonds link the molecules into (10-2) layers.

Rearrangement products of 3-methanesulfonyl-N-methyl-N-nitroaniline.

2003

Two isomeric products (C 8 H 10 N 2 O 4 S) of the rearrangement of 3-methanesulfonyl-N-methyl-N-nitroaniline have been investigated, viz. 3-methanesulfonyl-N-methyl-2-nitroaniline, which was the main product of the rearrangement, and 5-methanesulfonyl-N-methyl-2-nitroaniline. In both molecules, the aromatic rings are appreciably deformed towards ortho-quinonoidal geometry by electronic and steric interactions. The crystal structure is stabilized, in both cases, by weak C-H...O hydrogen bonds.

4,4,4′,4′,7,7′-Hexamethyl-2,2′-spirobichroman

2000

The title compound, C23H28O2, was obtained from the reaction of acetone with meta-cresol. The molecular structure consists of two identical subunits which are nearly perpendicular to each other. The oxygen-containing rings are not planar and the molecule is chiral. The crystal structure consists of chains of molecules of the same chirality arranged along the [010] axis.

The structure and phase transition of tris(n-propylammonium) enneachlorodiantimonate (III),

1996

The crystal structure of at 298 K has been determined (monoclinic, space group Cc, a = 19.464(2) ?, b = 17.736(2) ?, c = 8.116(2) ?, , Z = 4). The structure consists of one-dimensional polyanionic chains extended along the c-axis, and n-propylammonium cations located in elongated cavities formed by polyanions. The cations are connected to chlorine atoms by hydrogen bonds. Differential scanning calorimetry, the temperature dependence of the lattice parameters and static electric permittivity studies revealed a first-order phase transition at K of an `order - disorder' type. It is related to the ordering of n-propylammonium cations that occurs on decreasing the temperature. Debye-like dispers…

Structural and electronic contributions to hyperpolarizability in methyl p-hydroxy benzoate

2006

Abstract The single crystals of methyl p-hydroxy benzoate (MPHB) are grown from methanol solution by a low temperature solution growth technique. The SHG efficiency is tested using Q-switched Nd:YAG laser of wavelength λ at 1064 nm, which is approximately 1.2 times that of urea. Vibrational spectral analysis using NIR-FT Raman and FT-IR spectra is carried out to understand the structural and electronic contributions to hyperpolarizability in MPHB. The DFT computations are also performed at B3LYP/6-311G(d,p) level to derive equilibrium geometry, vibrational wavenumbers and intensities. The results of ab initio calculations at HF/6-311G(d,p) level show that the vibrational contribution for th…

Synthesis and structure of tetrakis(tetramethylammonium) octacosachlorooctaantimonate(III) [(CH3)4N]4Sb8Cl28

2000

Abstract The reaction between antimony trichloride and tetramethylammonium chloride in nitromethane gives transparent, irregular crystals of tetrakis(tetramethylammonium) octacosachlorooctaantimonate(III) [(CH 3 ) 4 N] 4 Sb 8 Cl 28 . Crystals are triclinic, space group P-1, a =11.846(2), b =12.217(2), c=14.120(3) A , α =95.71(3), β =101.39(3), γ =118.59(3)°, V=1713.7(5) A 3 , Z =1, d c =2.193, d m =2.17(2) Mg m −3 . The structure contains a structurally novel Sb 8 Cl 28 4- anion. It is composed of eight deformed octahedra, connected with each other by faces. In cavities formed by inorganic sublattice are located two crystallographically nonequivalent tetramethylammonium cations. One of them…

Deformation of the octahedral coordination of the Sb(III) atom in the structure of bis(1,2,4-triazolium) pentachloroantimonate(III) (C2H4N3)2[SbCl5]

2002

In the title compound the [SbCl 6] 3- octahedra show high variations in their Sb-Cl bond lengths and Cl-Sb-Cl angles. There are two crystallographically non-equivalent (C 2H 4N 3) + 1,2,4-triazolium cations in the crystal structure. They are located inside the cavities formed by the [{SbCl 5} 2-] n inorganic structure. The [{SbCl 5} 2-] n chains and (C 2H 4N 3) + cations are connected with each other by the N-H...Cl and C-H...Cl hydrogen bonds. Only two chloride atoms are involved in the N-H...Cl hydrogen bonds. The N-H...Cl interactions are responsible for the changing of geometries of Sb1-Cl2 and Sb1-Cl4 bonds and corresponding Cl-Sb-Cl angles. Their influence on the geometry of [SbCl 6] …

N-(3H-Thia­zol-2-yl­idene)­nitr­amine and N-methyl-N-(thia­zol-2-yl)­nitr­amine

2003

The geometries of the thiazole ring and the nitramino groups in N-(3H-thiazol-2-ylidene)nitramine, C 3 H 3 N 3 O 2 S, (I), and N-methyl-N-(thiazol-2-yl)nitramine, C 4 H 5 N 3 O 2 S, (II), are very similar. The nitramine group in (II) is planar and twisted along the C-N bond with respect to the thiazole ring. In both structures, the asymmetric unit includes two practically equal molecules. In (I), the molecules are arranged in layers connected to each other by N-H...N and much weaker C-H...O hydrogen bonds. In the crystal structure of (II), the molecules are arranged in layers bound to each other by both weak C-H...O hydrogen bonds and S...O dipolar interactions.

5-Formyl-2-furanboronic acid at 100 K

2003

The furan ring in the title compound, C5H5BO4, is planar and each of the formyl and boronic groups makes a dihedral angle of ca 3° with this ring. The geometry of the furan ring is somewhat different to that found for substituted and unsubstituted furan structures. The mol­ecules are connected to each other in the bc plane by C—H⋯O and O—H⋯O hydrogen bonds.

1,4-Dihydro-1-methyl-4-nitriminopyridine Dihydrate

1998

Molecules of the title compound, C6H7N302.2H20, are almost planar with the NNO2 nitrimino group twisted 8 (1) ° out of the plane of the pyridine ring. The nitrimino group and CsN ring form a conju- gated 7r-electron system. These molecules together with water molecules are arranged in planes, They are con- nected with each other by O--H.-.O, O--H...N and weaker C--H..-O hydrogen bonds. Four water mol- ecules form a planar square (OH..-O--H)2 ring with O-..O distances equal to 2.741 (2) and 2.778(2)A. These rings join pairs of molecular planes into double layers, interacting otherwise by van der Waals forces.

Vibrational spectral studies of methyl 3-(4-methoxyphenyl)prop-2-enoate, a new organic non-linear optic crystal

2005

Single crystals of methyl 3-(4-methoxyphenyl)prop-2-enoate were grown by the slow evaporation technique and vibrational spectral analysis was carried out using near-IR Fourier transform Raman and Fourier transform IR spectroscopy. Ab initio quantum computations were also performed at the HF/6–311G (d,p) level to derive the equilibrium geometry, vibrational wavenumbers and intensities and first hyperpolarizability. The large NLO efficiency predicted for the first time in this new class of compounds was confirmed by powder efficiency experiments. Hartree–Fock calculations reveal that the endocyclic angle at the junction of the propeonate group and the phenyl ring is decreased from 120° by 2.5…

ChemInform Abstract: 4,4,4′,4′,7,7′-Hexamethyl-2,2′-spirobichroman.

2010

The title compound, C23H28O2, was obtained from the reaction of acetone with meta-cresol. The molecular structure consists of two identical subunits which are nearly perpendicular to each other. The oxygen-containing rings are not planar and the molecule is chiral. The crystal structure consists of chains of molecules of the same chirality arranged along the [010] axis.

Phase transitions and distortion of [BiCl6]3- octahedra in (C3H5NH3)3[BiCl 6] - DSC and single-crystal X-ray diffraction studies

2004

The DSC diagram of tris(allylammonium) hexachlorobismuthate(III), (C3H5NH3)3[BiCl6], revealed three anomalies at 152, 191 and 299 K. The structure of the salt was determined at 200 and 315 K, below and above the high-temperature phase transition at 299 K. In both phases the crystals are monoclinic. At 200 K the space group is C2/c whereas at 315 K it is C2/m. The structures, at both temperatures, are composed of [BiCl6]3− octahedra and allylammonium cations. The organic and inorganic moieties are attracted to each other by a network of the N-H. . .Cl hydrogen bonds. The relationship between corresponding parameters of the unit cells has been found. The phase transition at 299 K, of the orde…

Structure and dynamic dielectric behaviour of ferroelectric [NH2(CH3)2]3Sb2Br9(DMABA)

2000

The crystal structure of DMABA has been determined at 293 and 180 K. It crystallizes in the monoclinic P21/c space group. The structure was refined to R1 = 0.0466 for 1269 independent reflections at 293 K and R1 = 0.038 for 1728 reflections at 180 K. DMABA is isomorphous with the chlorine analogue, DMACA. Its anionic sublattice forms corrugated two-dimensional layers in the bc plane. There are two crystallographically independent, disordered dimethylammonium cations in the crystal structure. One of them occupies cavities inside the polyanionic layers; the other is located between the layers. The temperature dependence of lattice parameters has been determined between 100 and 290 K. The pres…

Tetrakis(tert-butylammonium) benzene-1,2,4,5-tetracarboxylate octahydrate

2007

In the crystal structure of the title compound, 4C4H12N+·C10H2O8 4−·8H2O, there is a centre of symmetry at the centre of the benzene ring; the asymmetric unit comprises one half-anion, two cations and four water molecules. The pyromellitate tetraanion is nonplanar; it and the cations exhibit normal geometry. The two unique carboxylate groups are twisted out of the plane of the benzene ring by about 40 and 50°. The network formed by the ions and water molecules is based on eight O—H...O and six N—H...O strong hydrogen bonds.

High temperature ferro-paraelectric phase transition in tris(trimethylammonium) nonachlorodiantimonate(III) (TMACA) studied by X-ray diffraction meth…

2000

Abstract The structure of [NH(CH3)3]3Sb2Cl9, tris(trimethylammonium) nonachlorodiantimonate(III) (TMACA) has been determined at 295 K and 373 K, below and above the high temperature ferro-paraelectric phase transition. In both phases the anionic sublattice of TMACA is built of characteristic two-dimensional (Sb2Cl93−)n polyanionic layers lying in the bc plane. In room temperature, ferroelectric phase (monoclinic, Pc space group) there are three crystallographically non-equivalent trimethylammonium [NH(CH3)3]+ cations. Two of them are located between polyanionic layers and the third one, disordered, inside the cavity formed by six SbCl63− octahedra. In the high temperature paraelectric phase…

Bis(glycylglycinium) oxalate at 100 K.

2003

The structure of the title compound, 2C(4)H(9)N(2)O(3)(+).C(2)O(4)(2-), which has been determined by X-ray diffraction, contains discrete glycylglycine (HGly-Gly)(+) cations in general positions and oxalate anions which lie across centres of inversion. Although the geometry of the (HGly-Gly)(+) cation is not significantly different compared with other structures containing this residue, a few changes in conformation are observed which indicate the presence of molecular interactions. The molecular network in the crystal consists of one nearly linear O-H...O, five N-H...O and two weak C-H.O hydrogen bonds.

N-(tert-butoxycarbonylglycyl-alpha,beta-dehydrophenylalanylglycylphenylalanyl)-4-nitroaniline.

2000

In the crystal structure of the tetrapeptide Boc0–Gly1–ΔPhe2–Gly3–Phe4–p-NA (p-NA is para-nitro­aniline), C33H36N6O8, there are two independent mol­ecules differing in conformation in the asymmetric part of the unit cell. All the amino acids in the peptide are linked trans to each other. The torsion angles in the main chain of both mol­ecules are close to the values of the type β-II turn. Two intramolecular and three intermolecular N—H⋯O hydrogen bonds stabilize the conformation of each of the mol­ecules.

Structure of N,4-dinitroaniline and its complex with sulfolane at 85 K; on the proton donor–acceptor affinity of the primary nitramine (HNNO2) group

2001

The NNO2 group of the title compound is significantly less twisted with respect to the aromatic ring in comparison to a typical secondary nitramine. The amide nitrogen is trigonally hybridized. The nitramino group is almost planar. The C—C—N—N torsion angles vary between ca 13 and 42°, whereas the twist along the N—N bond is much smaller and amounts to between ca 1 and 15°. Those twist angles are governed by a crystal packing and are much larger in the case of crystals of pure N,4-dinitroaniline in comparison to that of its complex with sulfolane. The deviations of the internal angles of the aromatic ring from 120° do not exceed 3°. The presence of the nitro group increases the C—C—C valenc…

Structure and properties of tris(tetramethylammonium) nonabromodiarsenate(III), [(CH3)4N]3[As2Br9]

2007

The new tetramethylammonium bromoarsenate(III) crystal [(CH3)4N]3 [As2Br9] has been synthesized and its phase behaviour established by differential scanning calorimetry and dilatometry. Three phase transitions are found: at 346/346 K , at 165/171 K and at 157/165 K on cooling/heating. Single-crystal x-ray diffraction studies of phases I (at 370 K) and II (at 298 K) have shown that the structure comprises discrete [As2Br9]3− anions and disordered [(CH3)4N]+ cations. Phase II crystallizes in the polar space group P31c; its polar nature was confirmed by pyroelectric measurements. Phase I has higher symmetry, P63mc or . Dielectric dispersion measurements revealed a relaxation process in the cry…

Structure and properties of N-methyl-N-(4-pyridyl)-nitramine and 1,4-dihydro-1-methyl-4-nitriminopyridine

2002

Abstract The molecular structure and spectral properties of N -methyl- N -(4-pyridyl)-nitramine ( 1 ) and 1,4-dihydro-1-methyl-4-nitriminopyridine ( 3 ) were investigated by the X-ray diffraction, FTIR, nuclear magnetic resonance (NMR) methods and DFT theoretical calculations. N -methyl- N -(4-pyridyl)-nitramine ( 1 ) crystallises in the orthorhombic Pbca space group. It is composed of two planar fragments; nitramino (N 2 O 2 ) group and the pirydyl ring. These two groups are twisted at about 70° with respect to each other, along the Ar–N bond. On the contrary, in compound 3 , they are coplanar to each other. Twist of the nitramino group in 1 with respect to the pirydyl ring leads to a sign…

Structural characterization, thermal, dielectric and spectroscopic properties of di(n-pentylammonium) pentabromoantimonate(III): [n-C5H11NH3]2[SbBr5]

2008

Abstract The di( n -pentylammonium) pentabromoantimonate(III) compound has been synthesized and studied by means of a single-crystal X-ray diffraction, differential scanning calorimetry, thermal expansion, dielectric and IR techniques. Two solid–solid phase transitions of first order: at 416/388 K and 225/224 K (heating/cooling) have been revealed. The crystal structure of [ n -C 5 H 11 NH 3 ] 2 [SbBr 5 ] has been solved at 298 K, Pna 2 1 (phase II) and at 86 K P 2 1 2 1 2 1 (phase III). The crystal structure is composed of the SbBr 5 2 - anions which form an infinite chain and four independent n -pentylammonium cations. The dielectric studies have been made in the frequency range 500 Hz–1 …

On structural phase transitions in the (C 5 H 12 N) 2 SbCl 5 crystals

2000

Abstract The results of the X-ray (at 295 and 355 K), dilatometric, differential scanning calorimetry and dielectric studies on a new piperidinium crystal, (C5H12N)2SbCl5, are presented. The anionic sublattice of the crystal is built up of infinite (SbCl52−)n chains composed of SbCl63− distorted octahedra connected with each other by corners. In voids of anionic sublattice two crystallographically independent piperidinium cations are located. At 295 K they are both in chair conformation. The compound undergoes three first-order phase transitions at 378.5 K (I→II), 339.5 K (II→III) and 205 K (III→IV). The mechanism of the (II→III) transition (Pna21→P212121) was proposed based on the X-ray da…

STRUCTURE AND PHASE TRANSITIONS IN [C(NH2)3]SbCl6 CRYSTALS

1998

Abstract The crystal structure of [C(NH2)3]SbCl6 at 298 K (monoclinic, C2/m) and 240 K (monoclinic, P21/a) has been determined. The structure consists of isolated SbCl6− anions and guanidinium cations. Differential scanning calorimetry, dilatometric and dielectric studies revealed two structural phase transitions; a first-order one at 351 K and a second-order one at 265 K. One of the two crystallographically non-equivalent anions, SbCl6−(1), disordered in the room temperature phase is postulated to contribute to the phase transition mechanism at 265 K. A ferroelastic domain structure is found below 351 K.

The phase situation and ferroelectric properties in the mixed crystals [4-NH2PyH][SbCl4(1−x)Br4x]

2008

Abstract The group of mixed crystals of general formula: [4-APyH][SbCl4(1−x) Br4x] with x ranging from 0 to 1 was studied by means of differential scanning calorimetry, dilatometry and dielectric spectroscopy. The ferroelectric properties are preserved for mixed crystals with replacement fraction, x, less than 0.30. Moreover, such a substitution of the chlorine atoms by the bromine ones significantly lowers the temperature of the structural phase transition shifting it from 240 K for pure [4-APyH][SbCl4] to about 185 K for the mixed crystals richer in bromine. The dielectric relaxation process exhibited by the mixed crystal with x = 0.90 in the radio-frequency region was analyzed and the ac…

3-Formyl-2-furanboronic acid: X-ray and DFT studies

2004

The molecule of the title compound, C5H5BO4, is almost planar with the boronic acid group inclined to the furan ring by 3.7 (1)°. DFT (density functional theory) calculations at the B3LYP/6-311+G** level of theory (with no imaginary frequencies) were used to approximate the influence of hydrogen bonding on the molecular geometry and have confirmed the planarity of the mol­ecule. No significant differences in geometrical parameters in the solid state and in the gas phase are associated with the presence of the O—H⋯O intermolecular hydrogen-bonding network. The crystal packing is characterized by O—H⋯O hydrogen-bonded dimers, which are additionally linked by O—H⋯O, as well as C—H⋯O interactio…

N-Methyl-N-(2-nitrophenyl)nitramine andN-methyl-N-(3-nitrophenyl)nitramine

2005

The structures of the two title isomeric compounds (systematic names: N-meth­yl-N,2-dinitro­aniline and N-meth­yl-N,3-di­nitro­aniline, both C7H7N3O4) are slightly different because they exhibit different steric hindrances and hydrogen-bonding environments. The aromatic rings are planar. The –N(Me)NO2 and –NO2 groups are not coplanar with the rings. Comparison of the geometric parameters of the ortho, meta and para isomers together with those of N-meth­yl-N-phenyl­nitramine suggests that the position of the nitro group has a strong influence on the aromatic ring distortion. The crystal packing is stabilized by weak C—H⋯O hydrogen bonds to the nitramine group.

Distortions of [Sb2Cl10]4– Bioctahedra and Phase Transitions in the Chloroantimonate(III) (C3H5NH3)2[SbCl5]·(C3H5NH3)Cl

2007

Bis(allylammonium)pentachloroantimonate(III) - allylammonium chloride, (C3H5NH3)2[SbCl5] · (C3H5NH3)Cl, belongs to the chloroantimonate(III) organic-inorganic salts family. The DSC studies of this compound showed two anomalies at 181 K and at 223 K. Both are associated with phase transitions, which mainly occur due to ordering-disordering processes of the organic cations. Between 181 and 223 K the structure is incommensurate. The crystal structure was determined at 298 and 86 K. At both temperatures the crystal structure consists of (C3H5NH3)+ cations, anionic distorted [Sb2Cl10]4− units and isolated Cl− ions. In the room-temperature phase two out of three, and in the low-temperature phase …

1-Nitroindoline.

2000

In the title compound, C(8)H(8)N(2)O(2), the nitramino group is planar and only slightly twisted with respect to the indoline rings. The bridgehead N--C bond is slightly shorter than in typical secondary aromatic nitramines. The N--N bond has some double-bond character. The molecules are connected by weak C--H...O hydrogen bonds, forming chains parallel to the z direction.

DSC, Dilatometric, Dielectric, and1H NMR Studies of Phase Transitions and Molecular Motions in [N(C2H5)4]3M2Cl9 (M = Sb, Bi) Crystals

1995

Results in the dependence of stoichiometry of obtained tetraethylammonium (TEA) chloroantiomonate and chlorobismuthate salts on the molar ratio of reactants used in the synthesis are presented. Seven tetraethylammonium salts are obtained: (TEA) 6 M 8 Cl 30 , TEAMCI 4 , (TEA) 3 M 2 Cl 9 (M = Sb, Bi) and (TEA) 2 SbCl 5 . Preliminary X-ray diffraction studies on (TEA) 3 M 2 Cl 9 (M = Sb, Bi) show that they are isomorphous, crystallizing at room temperature in monoclinic symmetry. The dilatometric, dielectric, and DSC studies show that (TEA) 3 Bi 2 Cl 9 undergoes two phase transitions at T c2 = 144 K and at T c1 = 322 K while (TEA) 3 Sb 2 Cl 9 undergoes three transitions at T c3 = 185, T c2 = 2…

Synthesis of chloroantimonates(III) with selected organic cations. X-ray studies of phase transition in ferroelectric tris(trimethylammonium) nonachl…

2004

Abstract The dependence of molar ratio of reactants on the formula, crystal structure and physicochemical properties of chloroantimonates(III) with different organic cations was studied. It was proved, that the compounds show preferences in crystallization of one product. The changes of the molar ratio of substrates lead to the corresponding changes of these components in crystallized products. The structure of ferroelectric chloroantimonate(III), [(CH3)3NH]3[Sb2Cl9], was determined at 165 and 95 K. It crystallizes in monoclinic space group Pc: a=9.9612(11), b=9.0714(8), c=15.1807(14) A, β=90.086(8)°, R1=0.0202, wR2=0.0405 and a=9.9138(10), b=9.0783(7), c=15.1299(14) A, β=90.026(8)°, R1=0.0…

Structure and phase transition in (C2H5NH3)3Sb2Cl 9•(C2H5NH3)SbCl4; x-ray, DSC and dielectric studies

2000

Abstract The structure of (C2H5NH3)3Sb2Cl9 • (C2H5NH3)SbCl4 at 295 K has been determined. The crystals are orthorhombic, space group Pna21 (a -16.925(3), b = 24.703(5), c = 7.956(2) Å, V = 3326.4(12) Å3 , Z = 4, dc= 2.018, dm= 2.01(1) Mg m-3). They consist of an anionic sublattice composed of two different polymeric zig-zag chains. One is built of Sb2Cl9 3- units (corner sharing octahedra) and the other one is made of corner sharing SbCl5 2-square pyramids. In the cavites between the polyanionic chains four non-equivalent ethylammonium cations are located. Three of them are disordered. The cations are connected to the anions by weak N-H...Cl hydrogen bonds. A first order phase transition of…

Disorder in the crystals of trans-4-fluoroazoxybenzene. Synthesis, spectral properties, crystal structures and DFT calculations

2005

Abstract Two crystals of trans-4-fluoroazoxybenzene were obtained using two different methods. Oxidation of 4-fluoroazobenzene provided crystals of trans-4-fluoroazoxybenzene (I) consisting of two isomers; 51% α (ONN) and 49% β (NNO) isomer. From trans-amino-azoxybenzenes in Schiemann reaction it were obtained crystals of trans-4-fluoro-NNO-azoxybenzenes (II, β isomer) containing 4.7% of the α-isomer according to the HPLC analysis. The crystal structures of I and II were determined by the X-ray diffraction method. In the crystal I two nitrogen atoms of azoxy bridge and fluorine atom are disordered. In the crystal II, there are two independent molecules of trans-4-fluoroazoxybenzene; the mol…

Structure and Phase Transitions in Ethylenediammonium Dichloride and its Salts with Antimony Trichloride

2000

During the mixing of ethylenediammonium dichloride and antimony trichloride except of reported earlier [NH3(CH2)2NH3]5(Sb2Cl11)2 · 4 H2O a new salt [NH3(CH2)2NH3](SbCl4)2 was obtained. The crystals are monoclinic at 295 K, space group C2/m, a = 13.829(3), b = 7.408(1), c = 7.588(2) A; β = 103.18(3)°; V = 756.9(3) A3; Z = 2; dc = 2.585, dm = 2.56(2) g · cm–3. The structure consists of anionic sublattice built of Sb2Cl82– units composed of two SbCl52– square pyramids connected by edge. The ethylenediammonium cations are located in anionic cavities. The cations are disordered. Each methylene carbon atom is split between two positions. The X-ray diffraction, DSC, TGA and dilatometric methods we…

Structure and properties of some nitro derivatives of N -methyl- N -phenylnitramine

2000

Abstract Ten mono-, di- and tri-nitro derivatives of N-methyl-N-phenylnitramine were prepared and investigated using spectral and electrooptical methods. Three of them, viz. N-(2, 5-dinitrophenyl)-N-methylnitramine (monoclinic, P21/c, a=8.248(2), b=11.655(2), c=10.404(2) A , β=102.57(2)°), N-(2,3-dinitrophenyl)-N-methylnitramine (monoclinic, P21/c, a=9.224(2), b=7.222(2), c=15.458(4) A , β=101.08(2)°)) and N-(3,5-dinitrophenyl)-N-methylnitramine (monoclinic, P21/n, a=9.814(2), b=12.000(2), c=8.865(2) A , β=114.94(2)°) were examined by the X-ray diffraction method. The nitramino group is nearly planar with the short N(7)–N(8) bond and strongly electron deficient N(8) atom. The nitramino grou…

Ethylammonium 2,4,5-tricarboxybenzoate

2006

9-Ethoxy-1,5,13-trimethyl-8,10-dioxatetracyclo[7.7.1.02,7.011,16]heptadeca-2,4,6,11,13,15-hexaene

2009

The reaction of ethyl acetoacetate with meta-cresol in an acidic ionic liquid yielded a complex mixture of condensation products. 4,7-Dimethylcoumarin and the title compound, C20H22O3, were isolated. The title compound shows chemical but not crystallographic mirror symmetry. The two aromatic rings are inclined at an angle of 73.55 (6)°.

Crystal structure, phase transition and ferroelectric properties of the [(CH3)3NH]3[Sb2Cl9(1 x)Br9x] (TMACBA) mixed crystals

2003

The paraelectric–ferroelectric phase transition in the [(CH3)3NH]3[Sb2Cl9(1−x) Br9x] (TMACBA) mixed crystals is investigated by the differential scanning calorimetry, dilatometric and dielectric methods. The phase transition is found at 363.5, 362.7, 360.5 and 350.9 K (on cooling) for TMACBA crystals with x = 0, 0.02, 0.17 and 0.42, respectively. The crystal structures of the pure bromine analogue (x = 1), TMABA, and the mixed crystal TMACBA (x = 0.55) are determined at 297 K. TMABA crystallizes in the trigonal space group Rc: a = 15.098(2) A, c = 21.906(4) A, Z = 3, R1 = 0.0393, wR2 = 0.0746. Its structure is built up of discrete Sb2Br93− bioctahedra and disordered trimethylammonium cation…

Aminoguanidinium(2+) aminoguanidinium(1+) hexachloroantimonate(III) at 295 and 92 K

2001

The crystal and molecular structure of the title compound, (CH(7)N(4))(CH(8)N(4))[SbCl(6)], has been determined at 295 and 92 K. It is composed of isolated [SbCl(6)](3-) octahedra and aminoguanidinium mono- and dications. One of four of the crystallographically inequivalent aminoguanidinium cations is disordered at both temperatures. Two crystallographically inequivalent [SbCl(6)](3-) octahedra were found to possess three significantly longer Sb-Cl bonds than three other octahedra. The shorter bonds are in the range 2.456 (2)-2.577 (2) A, whereas the longer ones are between 2.705 (2) and 2.931 (2) A. Each short Sb-Cl bond is located trans to a long bond. It is argued that this deformation i…

The conformation cis of N-acetyl-N-methyl-α,β-dehydroalanine N′-methylamide and saturated analogues

2007

A series of three homologous amino acids derivatives: N-acetyl-N-methyl-α,β–dehydroalanine N′-methylamide (1), N-acetyl-N-methyl-L-alanine N′-methylamide (2), and N-acetyl-N-methyl-DL-alanine N′-methylamide have been synthesised. The racemic species undergoes spontaneous separation into L and D-enantiomers. From these two chiral forms, the structure of L-enantiomer (3) was analysed. The molecules of 1 – 3 adopt the cis arrangement of the N-terminal amide bond. The molecular conformations are similar for 1 (φ, ψ = 94.6(1)°, −1.7(1)°) and 3 (φ, ψ = 111.5(1)°, −23.8(1)°), and also 2 (φ, ψ = −114.8(2)°, 29.5(2)°), if inversion through the chiral C2 carbon is considered. They are stabilised by i…

Structure, phase transitions and molecular dynamics in ferroelastic crystal pyrrolidinium hexachloroantimonate(V), [C4H8NH2][SbCl6]

2005

Abstract The crystal structure of the pyrrolidinium hexachloroantimonate(V), [C4H8NH2][SbCl6], abbreviated PCA, has been determined by means of X-ray diffraction at 300 and 340 K. The space groups are monoclinic P 2 1 / n (phase III) and orthorhombic Pmnb (phase II), respectively. The crystal undergoes two structural phase transitions: first-order type at 356/329 K (heating/cooling) from phase (I) to (II) and second-order type at 323 K from phase (II) to (III). Dielectric studies suggest the plastic crystals behaviour above 356 K (phase I). Proton spin-lattice relaxation time ( T 1 ) and second moment ( M 2 ) of polycrystalline [C4H8NH2][SbCl6] have been determined at 77–370 K, at 90 and 25…

The structure, phase transition and molecular dynamics of [C(NH2)3]3[Sb2Br9]

2005

The crystal structures of [C(NH2)3]3[Sb2Br9] (Gu3Sb2Br9) at 300 K and of [C(NH2)3]3[Sb2Cl9] (Gu3Sb2Cl9) at 90 and 300 K are determined. The compounds crystallize in the monoclinic space group: C 2/c. The structure is composed of Sb2X93− (X = Cl, Br) ions, which form two-dimensional layers through the crystal, and guanidinium cations. In Gu3Sb2Br9 the structural phase transformation of the first-order type is detected at 435/450 K (on cooling/heating) by the DSC and dilatometric techniques. The dielectric relaxation process in the frequency range between 75 kHz and 5 MHz over the low temperature phase indicates reorientations of weakly distorted guanidinium cations. The proton 1H NMR second-…

Twotrans-4-aminoazoxybenzenes

2001

Two isomeric trans-4-aminoazoxybenzenes, trans-1-(4-aminophenyl)-2-phenyldiazene 2-oxide (alpha, C(12)H(11)N(3)O) and trans-2-(4-aminophenyl)-1-phenyldiazene 2-oxide (beta, C(12)H(11)N(3)O), have been characterized by X-ray diffraction. The alpha isomer is almost planar, having torsion angles along the C(aryl)-N bonds of only 4.9 (2) and 8.0 (2) degrees. The relatively short C(aryl)-N bond to the non-oxidized site of the azoxy group [1.401 (2) A], together with the significant quinoid deformation of the respective phenyl ring, is evidence of conjugation between the aromatic sextet and the pi-electron system of the azoxy group. The geometry of the beta isomer is different. The non-substitute…

On structural phase transitions in piperidinium halogenoantimonates(III) and bismuthates(III): X-ray, calorimetric, dilatometric, dielectric and Rama…

2000

Abstract Three piperidinium analogues: (C5H10NH2)2BiCl5, (C5H10NH2)2BiBr5 and (C5H10NH2)2SbBr5 have been studied by means of differential scanning calorimetry, thermal expansion, dielectric and Raman scattering techniques. Each piperidinium salt undergoes one high-temperature structural phase transition, which has been classified as an “order–disorder” type. All transitions are connected with onset of reorientational motion of the organic cations. The X-ray studies on (C5H10NH2)2BiCl5 show that it crystallises in orthorhombic Pna21 space group. The structure has been refined to R=0.0336. It consists of one-dimensional (BiCl52−)n polyanionic chains and two non-equivalent piperidinium cations…

Structure, phase transitions and molecular motions in ferroelastic (C4H8NH2)SbCl6·(C4H8NH2)Cl

2002

The crystal structure at 293 K of the new pyrrolidinium chloroantimonate (V) analogue, (C4H8NH2)SbCl6(C4H8NH2)Cl, has been determined by x-ray diffraction as monoclinic, space group P21/c, Z = 8. The crystal is built up of isolated SbCl6- anions, two types of inequivalent pyrrolidinium cation and isolated Cl- ions. It undergoes five solid-solid phase transitions: at 351/374 K of first-order type (cooling/heating, respectively), at 356 and 152 K second order and at 135/141 and 105/134 K first order, detected by differential scanning calorimetry, dilatometric and dielectric measurements. The ferroelastic domain structure appears between 152 and 135 K. The proton nuclear magnetic resonance sec…

Crystal structure and dielectric properties of the [(CH3)2NH2]3Sb2(1-x)Bi2xCl9(DMACAB) mixed crystals

2001

Phase transitions in [(CH3)2NH2]3Sb2(1-x)Bi2xCl9 (DMACAB) mixed salts in the composition range 0≤x≤0.41 have been investigated by the pyroelectric method and dielectric measurements over the frequency range from 75 kHz to 900 MHz. The phase situation is additionally confirmed by the differential scanning calorimetry (DSC) and dilatometric techniques. A transition from the paraelectric (PE) to the ferroelectric (FE) phase is observed for crystals with 0≤x≤0.14. Pyroelectric measurements support the presence of polar phases. The dynamic dielectric behaviour of ferroelectric systems is found to be determined by the existence of two independent relaxators. The low-frequency relaxator reveals a …

N-Methyl-3-methylsulfonyl-N-nitroaniline

2005

In the title compound, C8H10N2O4S, the N—N bond length [1.3488 (18) A] indicates some double-bond character, while the torsion angle between the aromatic ring and the nitramine group [66.3 (2)°] rules out further delocalization in the mol­ecule. The geometry of the methyl­sulfon­yl substituent is quasi-tetra­hedral, as expected. The crystal packing is stabilized by C—H⋯O hydrogen bonds, with the mol­ecules arranged in chains extended along the [101] direction.

Crystal and Molecular Structure of 1,2,4-Triazolium Chloride and its Salt with Antimony Trichloride - Bis(1,2,4-triazolium) pentachloroantimonate(III…

2002

The structures of 1,2,4-triazolium chloride (C2H4N3)Cl and its derivative with antimony trichloride - (C2H4N3)2[SbCl5] · (C2H4N3)Cl containing unsubstituted 1,2,4-triazolium cations were determined. (C2H4N3)Cl crystallizes in the monoclinic system, space group P21/n with the unit cell dimensions at 86 K: a = 9.425(2), b = 8.557(2), c = 11.158(2)Å , β = 95.87(3)°; V = 895.2(3)Å3, Z=8, dc = 1.566, dm = 1.56(2) g·cm-3.At roomtemperature, crystals of (C2H4N3)2- [SbCl5] · (C2H4N3)Cl are orthorhombic, space group P212121, a = 8.318(2), b = 11.381(2), c = 19.931(4) Å, V = 1886.8(7) Å3, Z = 4, dc = 1.917, dm = 1.91(2) g·cm-3. In both crystals the 1,2,4-triazole rings are planar. The anionic sublatt…

PHASE TRANSITIONS IN HALOGENOANTIMONATE(V) CRYSTALS: [N(CH3)4]SbCl6 AND [N(C2H5)4]SbCl6

1998

Abstract New crystals of the family of alkylammonium chloroantimonates(V), [N(CH 3 ) 4 ]SbCl 6 and [N(C 2 H 5 ) 4 ]SbCl 6 , have been grown and systematically studied. X-ray studies show that [N(C 2 H 5 ) 4 ]SbCl 6 is composed of isolated cations and ideal SbCl 6 − octahedra. Differential scanning calorimetry, dilatometric and dielectric measurements reveal structural phase transitions in [N(CH 3 ) 4 ]SbCl 6 and [N(C 2 H 5 ) 4 ]SbCl 6 of first order at 236 and 345 K, respectively. The measurements of 1 H-NMR spin-lattice relaxation times, T 1 , show that mechanism of the phase transitions in [N(CH 3 ) 4 ]SbCl 6 and [N(C 2 H 5 ) 4 ]SbCl 6 is due to the reorientations of the tetraalkylammoniu…

The structure and phase transition of mixed crystals

1996

The phase transition and molecular motions of methylammonium cations are studied in the temperature range from 110 to 450 K in the (x = 0.22, 0.345) (MACAB) crystal by x-ray DSC, dilatometric, dielectric and NMR techniques. It is shown that MACAB (x = 0.22) undergoes a structural phase transition at 222 K. The second moment of the NMR line () and the temperature dependence of spin lattice relaxation time () results are interpreted in terms of ( ion dynamics. In the high-temperature phase (I) the cations undergo isotropic reorientations. In the low-temperature phase (II) only one of three cations is still disordered, whereas the two others perform a type of reorientation about their C - N ax…

Optical investigation of phase transitions in Di(Tetraethylammonium) pentachloroantimonate(III) [N(C2H5)4]2SbCl5

1997

Abstract Spontaneous changes of linear birefringence in the [N(C2H5)4]2SbCl5 crystal were measured in the temperature range 200–500 K. Presence of two phase transitions at 219 K (monoclinic to orthorhombic) and at 347 K (orthorhombic to tetragonal) was confirmed. Two new phase transitions were found: -at 438 K (tetragonal to tetragonal) and at 467 K -to cubic phase.

N-(3-Methoxypropyl)-1,8-naphthalimide

2003

In the title compound, C16H15NO3, the 1,8-naphthaleno­dicarbox­imide group is nearly planar and, in the naphthal­imide ring system, the characteristic alternating pattern of bond lengths is observed. In the crystal, the mol­ecules are connected by a weak C—H⋯O hydrogen bond and extend in the direction parallel to the b axis.

1,5-Dimethyl-2-nitrimino-1,2-dihydropyridine

2006

Methyl­ation of 5-methyl-2-nitramino­pyridine provides the title compound, C7H9N3O2, as the only product. The mol­ecule consists of two planar fragments, viz. an aromatic ring and a nitrimino substituent. The NNO2 group is twisted by 17 (2)° out of the plane of the pyridine ring. Despite a small torsion angle between these fragments, the geometry of the mol­ecule indicates the participation of the π-electrons in the C—N bond. The hydrogen bonds in the crystal structure seem to be too weak to generate any deformations observed in the mol­ecule.

2,3-Dihydro-3-methyl-2-nitrimino-1,3-thiazole

2000

The title compound ¿alternatively, 3-methyl-2-[oxido(oxo)hydrazono]-2,3-dihydro-1,3-thiazole¿, C(4)H(5)N(3)O(2)S, was obtained by methylation of N-(2-thiazolyl)nitramine. The molecule lies on a mirror plane and the thiazole ring is planar, regular in shape and aromatic. The S atom participates in the aromatic sextet via an electron pair on the 3p(z) orbital. In the crystal, the molecules are arranged in parallel layers, bound to each other by weak C-H.O and C-H.N hydrogen bonds and by S.O dipolar interactions, with an interlayer separation of 3.23 A.

Synthesis of 2-Aminothiazole Derivatives in Easy Two-Step, One-Pot Reaction

2018

On structural phase transitions inn-butylammonium chloroantimonate(III) and chlorobismuthate(III) crystals: x-ray, differential scanning calorimetry,…

1997

Numerous structural phase transitions are detected in new crystals of the n-butylammonium compounds: , and by means of differential scanning calorimetry, dilatometric and dielectric dispersion (1 kHz - 1 MHz) studies. For the transitions the basic thermodynamic data are determined. Interesting dielectric properties are found in a metastable form of the crystals. Debye-like dispersion of the electric permittivity between 30 and 800 MHz is observed around the 310 K phase transition for this crystal. The activation energy of the reorientation of the n-butylammonium cations is found to be 16 kJ . The structure of ( form) has been refined to R = 0.0439 and shows isolated units and two non-equiva…

2,4,6-Trimethyl-N-nitroaniline

2007

In 2,4,6-trimethyl-N-nitro­aniline (alternatively called mesitylnitramine), C9H12N2O2, the primary nitramino group is planar with a short N—N bond and is nearly perpendicular to the aromatic ring. The methyl group located in the para position is disordered, each H atom having half-occupancy. The mol­ecules are linked together along the [100] axis by inter­molecular N—H⋯O hydrogen bonds.

Tris(1,10-phenanthroline)zinc(II) dichromate tetrahydrate

2002

The title compound, [Zn(C12H8N2)3][Cr2O7]·4H2O, was obtained by mixing 1,10-phenanthroline (phen), potassium chromate and zinc sulfate solutions. The asymmetric unit is composed of a [Zn(phen)3]2+ cation, a Cr2O72− anion and four water mol­ecules. The ZnII ion is in a distorted octahedral environment, coordinated by six N atoms from three phen mol­ecules. The cations are connected to anions by weak C—H⋯O hydrogen bonds, with shortest H⋯O distances of ca 2.27–2.33 A. The Cr2O72− anion is in a staggered conformation. Two of the four crystallographically independent water mol­ecules are ordered, and two others are disordered, each over two sites.

Crystal structure, dielectric properties and molecular motions in ( i -C 4 H 9 NH 3 ) 3 Bi 2 Br 9

2000

Abstract The crystal structure of ( i -C 4 H 9 NH 3 ) 3 Bi 2 Br 9 at room temperature has been determined and refined to R =0.036. The crystal is orthorhombic, space group Ama 2. The structure is built up of the i -butylammonium cations and isolated Bi 2 Br 9 3− anions. The complex dielectric permittivity along the a -axis has been measured between 500 Hz and 1000 MHz in the vicinity of two phase transitions at 252 and 263 K. The dielectric response close to 252 K is well described by the Debye equation. The activation energy of the reorientation of the i -butylammonium cations is found to be 0.68 eV. The temperature dependencies of the proton relaxation time T 1 and of the second moment of…

Tetrakis(1-ethyl-1H-1,2,4-triazole-κN4)bis(nitrato-κO)copper(II) and bis(nitrato-κO)tetrakis(1-propyl-1H-1,2,4-triazole-κN4)copper(II)

2005

The copper(II) environments for tetrakis(1-ethyl-1,2,4-triazole)dinitratocopper(II), [Cu(NO 3 ) 2 (C 4 H 7 N 3 ) 4 ], and tetrakis-(1-propyl-1,2,4-triazole)dinitratocopper(II), [Cu(NO 3 ) 2 (C 5 -H 9 N 3 ) 4 ], are distorted square bipyramidal. Both structures are centrosymmetric, with the copper(II) ions located at inversion centers coordinated by four N atoms of four triazole molecules and by two O atoms of two nitrate ions in an elongated octahedral geometry. This elongation is a result of the Jahn-Teller effect. The largest distortion is that of the N-Cu-O angles, which differ from 90 by 5.68 (10)° in the ethyl and 5.59 (8)° in the propyl derivative.

Methyl 3-(4-methoxyphenyl)prop-2-enoate

2001

The title molecule, C(11)H(12)O(3), is almost planar, with an average deviation of the C and O atoms from the least-squares plane of 0.146(4)A. The geometry about the C=C bond is trans. The phenyl ring and -COOCH(3) group are twisted with respect to the double bond by 9.3(3) and 5.6(5) degree, respectively. The endocyclic angle at the junction of the propenoate group and the phenyl ring is decreased from 120 degree by 2.6(2) degree, whereas two neighbouring angles around the ring are increased by 2.3(2) and 0.9(2) degree. This is probably associated with the charge-transfer interaction of the phenyl ring and -COOCH(3) group through the C=C double bond. The molecules are joined together thro…

4-hydroxy-ONN-azoxybenzene

2000

The oxidation of 4-hydroxy­azo­benzene provided a mixture of two azoxy compounds, which were separated by column chromatography. The isomer with the higher melting point appeared to belong to the α (ONN) series, as determined by X-ray diffraction. The mol­ecule, C12H10N2O2, is almost planar. The benzene rings are twisted by 11.7 (2) (substituted) and 4.1 (1)° (unsubstituted) with respect to the ONN plane. The mol­ecules are connected to one another by strong O—H⋯O hydrogen bonds forming chains extended along [001], which are bound by much weaker C—H⋯O hydrogen bonds forming layers in the bc plane.

1-Methyl-4-nitraminopyridinium nitrate and 4-nitraminopyridinium methanesulfonate

2001

In the title compounds, C6H8N3O2+*NO3- and C5H6N3O2+*-CH3SO3-, respectively, the cations are almost planar; the twist of the nitramino group about the C-N and N-N bonds does not exceed 10 degrees. The deviations from coplanarity are accounted for by intermolecular N-H...O interactions. The coplanarity of the NHNO2 group and the phenyl ring leads to the deformation of the nitramino group. The C-N-N angle and one C-C-N angle at the junction of the phenyl ring and the nitramino group are increased from 120 degrees by ca 6 degrees, whereas the other junction C-C-N angle is decreased by ca 5 degrees. Within the nitro group, the O-N-O angle is increased by ca 5 degrees and one O-N-N angle is decr…

Structure and phase transitions in guanidinium halogenobismuthates(III)

2001

Abstract Differential scanning calorimetry (DSC), dilatometric and dielectric measurements have been used to study the phase transitions in [C(NH2)3]3BiBr6. The [C(NH2)3]3BiBr6 crystal undergoes four phase transitions: at 419, 429, 475 and 495 K (on heating). The high-temperature phase transition is clearly of first-order type and its high entropy effect allows classifying it as of the order–disorder type. X-ray diffraction studies showed that [C(NH2)3]3BiBr6 crystallises in monoclinic, centrosymmetric space group, C2/c. The anionic sublattice is composed of isolated BiBr63− octahedra. The infrared between 100 and 350 K and Raman spectra at room temperature in the frequency range related to…

β-(3,6,9-Trimethyl-9-xanthenyl)propionic acid

2007

The title compound, C19H20O3, was obtained, among other condensation products, from the reaction of meta-cresol and levulinic acid. The pyrane ring closure does not alter significantly the environment of the ethereal linkage in comparison with diaryl ethers. The deformations of the endocyclic valence angles in the benzene rings, centred on the C atoms substituted with alkyl groups, is greater than expected. The mol­ecular packing is influenced by O—H⋯O hydrogen bonds, leading to centrosymmetric dimers.

Bis(tert-butylammonium) oxalate

2006

The component species in the title compound, 2C4H12N2+·C2O42−, inter­act by way of N—H⋯O hydrogen bonds, resulting in a layered network. N and two C atoms of the cation possess site symmetry m and the C atom of the anion has site symmetry 2.

N′-(2-Fluorobenzoyl)benzohydrazide

2008

In the crystal structure of the title compound, C(14)H(11)FN(2)O(2), the molecule is centrosymmetric. The F atom is disordered over four positions, on the two ortho positions of each ring, with occupancies of 0.287:0.213 (5). In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯O and C-H⋯O hydrogen bonds.

Structure and properties of 2-cyanopyridinium perchlorate [2-CNPyH][ClO4]

2006

The crystal structure of 2-cyanopyridinium perchlorate, [2-CNPyH][ClO4], has been determined at 100 (phase II) and 293 K (phase I). It is monoclinic P 21 at 100 K and orthorhombic P 212121 at 293 K. The dynamic properties of the crystal were studied by differential scanning calorimetry, dilatometry, pyroelectric, dielectric, proton (1H NMR), chlorine (35Cl NMR) magnetic resonance spectroscopies and the infrared method. The crystal undergoes a structural phase transition () at 170 K characterized by a complex mechanism involving both 'order–disorder' and 'displacive' contributions. It reveals pyroelectric properties below 170 K. The dielectric relaxation existing over phase I is due to the m…

Structure and phase transitions in the ferroelastic [C(NH2)3]3Bi2Br9crystal

1999

Differential scanning calorimetry, dilatometric, dielectric and linear birefringence measurements have been used to study the ferroelastic [C(NH2)3]3Bi2Br9 crystal. The x-ray studies showed that it crystallizes at room temperature in the monoclinic symmetry, space group P21/m. The crystal undergoes a complex sequence of phase transitions: at 311 K, 333.5 K, 350 K, 415 K and 425 K. All phase transitions were found to be of first order type. The ferroelastic domain structure is maintained from room temperature up to 425 K. The temperature measurements of the linear birefringence and optical observations suggest the tetragonal symmetry of the parent paraelastic phase above 425 K.

Tris(N,N,N′,N′‐tetra­methyl­guanidinium) nona­bromo­dianti­monate(III)

2006

In the title compound, [NH2C(N(CH3)2)2]3[Sb2Br9], the organic cations inter­act with the isolated [Sb2Br9]3− anions by way of N—H⋯Br hydrogen bonds, leading to some deformations of the inorganic unit.

Crystal structure, phase transitions and ferroelastic properties of [(CH3)2NH2]3[Bi2Cl9]

2003

Abstract A sequence of structural phase transitions in [(CH3)2NH2]3[Bi2Cl9] (DMACB) is established on the basis of differential scanning calorimetry (DSC) and dilatometric studies. Four phase transitions are found: at 367/369, 340/341, 323/325 and 285/292 K (on cooling/heating). The crystal structure of DMACB is determined at 350 K. It crystallizes in monoclinic space group P21/n: a=8.062(2), b=21.810(4), c=14.072(3) A, β=92.63(3)°, Z=4, R1=0.0575, wR2=0.1486. The crystal is built of the double chain anions (“pleated ribbon structure”) and the dimethylammonium cations. Dielectric studies in the frequency range 75 kHz–900 MHz indicate relatively fast reorientation of the dimethylammonium cat…

Intramolecular charge delocalization and nonlinear optical properties of Methyl 3-(4-methoxy phenyl) prop-2-enoate from vibrational spectra

2005

The density functional computations of MMP are performed at B3LYP/6-31G (d,p) level to derive equilibrium geometry, vibrational wavenumbers and intensities, and first hyperpolarizability. Large NLO efficiency predicted for the first time in this new class of compounds has been confirmed by powder efficiency experiments. DFT calculation reveals that endocyclic angle at the junction of the propenoate group and the phenyl ring is decreased from 120° by 2.5°, whereas two neighbouring angles around the ring are increased by 2.1° and 1.2° respectively, associated with intramolecular charge transfer interaction. The vibrational spectra confirm the charge transfer interaction between -COOCH3 group…

Tetrakis(methylammonium) benzene-1,2,4,5-tetracarboxylate dihydrate

2006

In the title compound, 4CH6N+·C10H2O8 4−·2H2O, the complete C10H2O8 4− anion is generated by inversion; one of the unique carboxylate groups is almost coplanar with the benzene ring, perhaps as the result of intramolecular C—H...O interactions, and the other is almost perpendicular. A network of O—H...O and N—H...O hydrogen bonds helps to consolidate the crystal packing.

Preparation, crystal structure at 298 and 90 K and phase transition in (C2H5NH3)2 [SbBr5] studied by the single crystal X-ray diffraction method

2004

The reaction of antimony(III) oxide with ethylamine, in molar ratios from 1:1 to 1:10, in concentrated hydrobromic acid leads to the formation of one product - bis(ethylammonium) pentabromoantimonate( III). The structure of (C2H5NH3)2[SbBr5] was determined at 298 and 90 K, below and above the phase transition that occurs at about 158.5 K. The orthorhombic system was found in both phases, space groups Cmca and Pbca at 298 and 90 K, respectively. At both temperatures the structure consists of [SbBr6]3− octahedra connected via cis bromine atoms forming one-dimensional zig-zag [{SbBr5}2−]n chains. The ethylammonium cations fill the space between polyanionic chains. The organic and inorganic sub…

Diisopropyl [(2-hydroxy-1-naphthyl)methyl]phosphonate

2003

The bond lengths and angles in the title compound, C17H23PO4, are in accordance with anticipated values. There are two conformers in the asymmetric unit. They differ from each other in the orientation of the C and P tetrahedra. Analysis of the structure does not reveal any significant differences between the bond distances and angles of the mol­ecules in the asymmetric unit. In the crystal structure, the conformers are linked by O—H⋯O=P and C—H⋯O hydrogen bonds.

Structure of chloroantimonates(III) with an imidazolium cation: (C3H5N2)[SbCl4] and (C3H5N2)2[SbCl5]

2003

Abstract Two different chloroantimonates(III) with an imidazolium cation have been synthesized by the reaction of antimony trichloride and imidazole in an aqueous solution of hydrochloric acid. The crystals of (C3H5N2)[SbCl4] are monoclinic, space group C2/c, while (C3H5N2)2[SbCl5] crystallizes in the orthorhombic system, space group Pbcn. Both crystals are built of one dimensional zig-zag chains composed of [SbCl6]3− octahedra connected by edges and corners, respectively. The cavities between inorganic chains are filled by imidazolium cations. In both structures, one crystallographically independent imidazolium cation is rotationally disordered, and the positions of all atoms are split bet…

3-formylphenylboronic acid.

2004

The molecule of the title compound, C(7)H(7)BO(3), is planar, and the bond lengths and angles are typical. The formyl group is essentially coplanar with the benzene ring but does not influence significantly the distortion of the ring, although the formyl group does have a strong influence on the crystal packing. The geometry of the boronic acid group is typical. In the crystal structure, the molecules are linked by O-H...O hydrogen bonds.

Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints

2011

Nitramines and related N-nitro compounds have attracted significant attention owing to their use in rocket fuel and as explosives. The charge density of 1-nitroindoline was determined experimentally and from theoretical calculations. Electron-density refinements were performed using the multipolar atom formalism. In order to design the ideal restraint strategy for the charge-density parameters, R-free analyses were performed involving a series of comprehensive refinements. Different weights were applied to the charge-density restraints, namely the similarity between chemically equivalent atoms and local symmetry. Additionally, isotropic thermal motion and an anisotropic model calculated by …

Crystal and molecular structure of 1,2-dihydro-1-methyl-2-nitriminopyridine: X-ray and infrared studies

1999

Abstract The crystal and molecular structure of 1,2 dihydro-1-methyl-2-nitriminopyridine ( 1 ) at 90.0(1) K have been determined. It crystallises in an orthorhombic Pna2 1 space group with a =7.753(2), b =13.829(3) and c =6.070(1) A, Z =4, R ( F )=0.0259 for 1856 unique reflections. The pyridine ring is planar, the N(1) nitrogen atom remains sp 2 hybridised. The NNO 2 group is twisted 26° along C–N bond and 15° along N–N bond. The twist is caused by a steric hindrance and/or weak C–H⋯O hydrogen bonds. IR spectra of ( 1 ), N -(2-pyridyl)-nitramine ( 4 ) and N -methyl- N -(2-pyridyl)-nitramine ( 9 ) were recorded in solution and in the solid state. The frequencies characteristic of the nitrim…

Phase transitions in i-butylammonium halogenoantimonate(III) and bismuthate(III) crystals

1997

Abstract Differential scanning calorimetry, dielectric, thermal expansion, infrared and preliminary X-ray diffraction studies on i-butylammonium halogenoantimonate(III) and bismuthate(III) crystals are reported. All crystals: (i-C4H9NH3)2BiCl5, (i-C4H9NH3)2SbBr5, (i-C4H9NH3)3BiCl6, (i-C4H9NH3)3Bi2Br9, (i-C4H9NH3)3Sb2Br9, show one or more structural phase transitions of first order type. The values of the transition entropies suggest that the most of the phase transitions are of the order-disorder type. The infrared studies confirmed the contribution of the i-butylammonium cations in the phase transition mechanism.

Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints. Corrigendum

2011

The D e (dissociation energy) values in Table 6 of the article by Zarychta et al. [(2011). Acta Cryst. B67, 250–262] are corrected.

1H NMR, DSC, dielectric, and dilatometric studies of phase transitions and molecular dynamics in N (C2H5)4SbCl4

1994

The results of dielectric, dilatometric, 1H NMR, and DSC studies on N(C2H5)4SbCl4 crystals are presented. The title compound undergoes two phase transitions at Tc1 = 272 K reversible of first order and at Tc2 = 393 K irreversible. The values of transition entropies and enthalpies are compared with those of other tetraethylammonium halogenoantimonates and bismuthates (III). The spin-lattice relaxation times and the values of the second moments of the 1H NMR line for the N(C2H5)4SbCl4 crystal are measured in the temperature range of 70 to 400 K. Two minima of T1 are observed. They are attributed to CH3 group reorientations. The activation energies for the processes are determined.

9,9′-Bianthracenyl

2007

The title compound, C28H18, has two nearly planar anthracenyl fragments which are twisted with respect to one another by 80.54 (2)° around the central C—C bond which is very long [1.4954 (17) Å]. The structure differs from the already known polymorph [Langer, Sieler & Becker (1992). Z. Kristallogr. 199, 300–303].

2-Amino-5-butyl-4-methyl-1,3-thia­zol-3-ium nitrate

2003

The title compound, C8H15N3O3S, shows bond lengths and angles that are typical and are in accordance with expected values. The structure comprises a substituted thia­zolium ring that is connected to a nitrate ion via N-H...O hydrogen-bonding interactions.

trans-4-Bromo-ONN-azoxybenzene at 100 K.

2004

The crystal structure of the alpha isomer of trans-4-bromoazoxybenzene [systematic name: trans-1-(bromophenyl)-2-phenyldiazene 2-oxide], C(12)H(9)BrN(2)O, has been determined by X-ray diffraction. The geometries of the two molecules in the asymmetric unit are slightly different and are within approximately 0.02 A for bond lengths, approximately 2 degrees for angles and approximately 3 degrees for torsion angles. The azoxy bridges in both molecules have the typical geometry observed for trans-azoxybenzenes. The crystal network contains two types of planar molecules arranged in columns. The torsion angles along the Ar-N bonds are only 7 (2) degrees, on either side of the azoxy group.

N,N,N',N'‐Tetramethylguanidinium tetrachloroantimonate(III) at 295 and 92K

1999

The crystal structure of N,N,N',N'-tetramethylguanidinium tetrachloroantimonate(III), (C 5 H 14 N 3 )[SbCl 4 ], has been determined at 295 and 92 K. Each Sb atom is surrounded by six Cl atoms forming an irregular [SbCl 6 ] 3- octahedron. The octahedra are connected with each other in infinite zigzag chains. There is one crystallographically independent N,N,N',N'-tetramethylguanidinium cation in the crystal structure. It is linked to the [SbCl 6 ] 3- octahedra through N-H...Cl hydrogen bonds. The deformation of the octahedral coordination of the Sb III atom is related to the presence of N-H...Cl hydrogen bonds.

Orthorhombic polymorphs of twotrans-4-aminoazoxybenzenes

2002

The two isomeric compounds 4-amino-ONN-azoxybenzene [or 1-(4-aminophenyl)-2-phenyldiazene 2-oxide], i.e. the alpha isomer, and 4-amino-NNO-azoxybenzene [or 2-(4-aminophenyl)-1-phenyldiazene 2-oxide], i.e. the beta isomer, both C(12)H(11)N(3)O, crystallized from a polar solvent in orthorhombic space groups, and their crystal and molecular structures have been determined using X-ray diffraction. There are no significant differences in the bond lengths and valence angles in the two isomers, in comparison with their monoclinic polymorphs. However, the conformations of the molecules are different due to rotation along the Ar-N bonds. In the alpha isomer, the benzene rings are twisted by 31.5 (2)…

Dependence of the distortion of the square pyramids in N,N-dimethylethylenediammonium pentachloroantimonate(III) on the geometry of hydrogen bonds

2001

Abstract N ,N-Dimethylethylenediammonium pentachloroantimonate(III) crystallizes in the monoclinic system, in space group P21/c (a = 12.460(2), b = 10.252(2), c = 10.330(2) Å, β = 97.75(3)°, V = 1307.5(4) Å3, Z = 4, dc = 1.997, dm = 1.99(2) g/cm3). The crystal structure of [(CH3)2NH(CH2)2NH3][SbCl5] consists of isolated [SbCl5]2- anions and [(CH3)2NH(CH2)2NH3]2+ cations. The [SbCl5]2- anion has a distorted square pyramidal geometry, presenting one short axial and four long equatorial Sb-Cl bonds. The square pyramids are characteristically stacked one close to the other, parallel to the c axis. The voids between the anionic sublattice are filled by [(CH3)2NH(CH2)2NH3]2+ cations. The five non…

Structural characterization, thermal, dielectric, vibrational properties and molecular dynamics of (C5H5NH)3BiCl6

2009

Abstract (C5H5NH)3BiCl6 crystallizes at room temperature in the triclinic space group P 1 ¯ . The crystal is built up of the separated BiCl 6 3 - octahedral anions and pyridinium cations. Differential scanning calorimetry (DSC) and dilatometric measurements disclose structural phase transition of first-order type at 265/302 K (cooling/heating). The dielectric investigations reveal a step-wise change of the electric permittivity at Tc characteristic of the crystals with the high-temperature plastic-like phase. Temperature-dependent infrared spectra for polycrystalline samples have been taken between 20 and 306 K to clarify the cation dynamics contribution to the mechanism of the phase transi…

CCDC 623096: Experimental Crystal Structure Determination

2018

Related Article: Błażej Dziuk, Janusz B. Kyzioł, Jacek Zaleski, Krzysztof Ejsmont, Bartosz Zarychta|2018|J.Heterocycl.Chem.|55|763|doi:10.1002/jhet.3086

CCDC 623097: Experimental Crystal Structure Determination

2018

Related Article: Błażej Dziuk, Janusz B. Kyzioł, Jacek Zaleski, Krzysztof Ejsmont, Bartosz Zarychta|2018|J.Heterocycl.Chem.|55|763|doi:10.1002/jhet.3086