Conformational Comparisons Between Phenoxyacetic Acid Derivatives in Adducts and in the Free Form

1999 ◽  
Vol 52 (7) ◽  
pp. 695 ◽  
Author(s):  
Graham Smith ◽  
Catherine J. Cooper ◽  
Veena Chauhan ◽  
Daniel E. Lynch ◽  
Simon Parsons ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Single Crystal ◽  
Free Acid ◽  
Molecular Complexes ◽  
The Other ◽  
Free Form ◽  
Phenoxyacetic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dichlorophenoxy Acetic Acid

Six molecular complexes containing the herbicidally active (2,4-dichlorophenoxy)acetic acid (2,4-d) and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-t) have been prepared and studied by using single-crystal X-ray diffraction techniques. These adduct structures are 2,4-d with 4,4′-dipyridine (2 : 1 complex), and 2,4,5-t with respectively 5-nitroquinoline (1 : 1), 4,4′-dipyridine (2 : 1), 2-amino-2-thiazoline (1 : 1), 2-aminobenzothiazole (1 : 1) and 2-amino-5-ethyl-1,3,4-thiadiazole (1 : 1). The conformations of the phenoxyacetic acid molecules were found to be either synclinal (in three cases) or antiperiplanar (in the other three cases). A general review is also made about the conformational aspects of previously reported adducts of phenoxyacetic acid derivatives and how they compare to their free acid structures.

Molecular Cocrystals of Carboxylic Acids. XV. Preparation and Characterization of Heterocyclic Base Adducts With a Series of Carboxylic Acids, and the Crystal Structures of the Adducts of 2-Aminopyrimidine With 2,6-Dihydroxybenzoic Acid, 4-Aminobenzoic Acid, Phenoxyacetic Acid, (2,4-Dichlorophenoxy)acetic Acid, (3,4-Dichlorophenoxy)-acetic Acid and Salicylic Acid, and 2-Aminopyridine With 2,6-Dihydroxybenzoic Acid

1994 ◽  
Vol 47 (6) ◽  
pp. 1097 ◽  
Author(s):  
DE Lynch ◽  
G Smith ◽  
D Freney ◽  
KA Byriel ◽  
CHL Kennard
Keyword(s):  
Acetic Acid ◽  
Salicylic Acid ◽  
Carboxylic Acids ◽  
Phenoxyacetic Acid ◽  
Aminobenzoic Acid ◽  
X Ray Diffraction ◽  
Dihydroxybenzoic Acid ◽  
Heterocyclic Base ◽  
X Ray ◽  
Dichlorophenoxy Acetic Acid

The molecular adducts of the heterocyclic base 2-aminopyrimidine with the aromatic and aromatic aliphatic carboxylic acids salicylic acid, 2,6-dihydroxybenzoic acid and 4-aminobenzoic acid, phenoxyacetic acid, (2,4-dichlorophenoxy)acetic acid, and (3,4-dichlorophenoxy)acetic acid have been prepared, and their interactive modes characterized by single-crystal X-ray diffraction methods. In addition, the complexes with (4-chlorophenoxy)acetic acid, (2,3-dichlorophenoxy)acetic acid, (4-chloro-2-methylphenoxy)acetic acid and (2,4,5- trichlorophenoxy)acetic acid have been characterized by analytical methods, including infrared spectroscopy. Except for the phenoxyacetic acid adduct (2:1), all form 1:1 molecular associations in which the carboxylic acid shows a variable tendency to protonate the hetero nitrogen of the base. The 1:1 complex of 2-aminopyridine with 2,6-dihydroxybenzoic acid has also been characterized by single-crystal X-ray diffraction.

Metal Phenoxyalkanoic Acid Interactions. XXV. The Crystal Structures of (2-Formyl-6-Methoxyphenoxy)Acetic Acid and Its Zinc(II) Complex and the Lithium, Zinc(II) and Cadmium(II) Complexes of (2-Chlorophenoxy)Acetic Acid

1987 ◽  
Vol 40 (7) ◽  
pp. 1147 ◽  
Author(s):  
EJ Oreilly ◽  
G Smith ◽  
CHL Kennard ◽  
TCW Mak
Keyword(s):  
Acetic Acid ◽  
Crystal Structures ◽  
Free Acid ◽  
Rotational Symmetry ◽  
Carboxyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Third ◽  
Planar Complex ◽  
Hydrogen Bonded

The crystal structures of (2-formyl-6-methoxyphenoxy)acetic acid (1), diaquabis [(2-formyl-6-methoxyphenoxy) acetato ]zinc(11) (2), tetraaquabis [(2-chlorophenoxy) acetato ]zinc(11) (3), triaquabis [(2-chlorophenoxy) acetato ]cadmium(11) dihydrate (4) and lithium (2-chloro- phenoxy )acetate 1.5 hydrate (5) have been determined by X-ray diffraction. The acid (1) forms centrosymmetric hydrogen-bonded cyclic dimers [O…0, 2.677(6) �] which are non-planar. Complex (2) is six-coordinate with two waters [Zn- Ow , 1.997(2) �] and four oxygens from two asymmetric bidentate carboxyl groups [Zn-O, 2.073, 2.381(2) �] completing a skew trapezoidal bipyramidal stereochemistry. Complex (5) is also six-coordinate but is octahedral, with two trans-related unidentate carboxyl oxygens [mean Zn-O, 2.134(9) �] and four waters [mean Zn-O, 2.081(9) �]. The seven-coordinate complex (4) has crystallographic twofold rotational symmetry relating two :symmetric bidentate acid ligands [ Cd -O, 2.26, 2 48(:) �] and two waters [ Cd -O, 2.34(2) �] while the third water lies on this axis [ Cd -O, 2.27(2) �]. In contrast to the monomers (2)-(4), complex (5) is polymeric with tetrahedral lithium coordinated to one water and three carboxylate oxygens [mean Li-0, 1.95(1) �]. The essential conformation of the free acid is retained in complexes (2), (3) and (4) but in (5), it is considerably changed.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

Crystal Structure of Calcium Picrate Pentahydrate: A New Eight-Coordinate Stereochemistry for [M(bidentate)2(unidentate)4]

1979 ◽  
Vol 32 (2) ◽  
pp. 301 ◽  
Author(s):  
V Diakiw ◽  
TW Hambley ◽  
DL Kepert ◽  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Single Crystal ◽  
Title Compound ◽  
Lattice Site ◽  
The Other ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Triangular Face ◽  
X Ray

The crystal structure of the title compound, Ca(C6H2N307)2,5H2O, has been determined by single-crystal X-ray diffraction at 295(1) K and refined by least squares to a residual of 0.049 for 1513 'observed' reflections. Crystals are orthorhombic, Pmab, a 24.169(6), b l0.292(7), c 8.554(2) �, Z 4. The stereochemistry about the calcium has not been observed previously for the system [M(bidentate)2- (unidentate)4]; in the present structure, the calcium is coordinated by a pair of bidentate picrate ligands and the four water molecules in an array in which three of the water molecules occupy a triangular face of a square antiprism, the overall array having m symmetry. The remaining water molecule occupies a lattice site with no close interaction with the other species.

Synthesis and Structure of and Cation Distribution in the Zirconium Cluster Rb[(Zr6C)Cl15]

2008 ◽  
Vol 63 (5) ◽  
pp. 507-512 ◽  
Author(s):  
Henning W. Rohm ◽  
Martin Köckerling
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Cation Distribution ◽  
Type Structure ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coulombic Interactions ◽  
Cluster Network ◽  
Zirconium Cluster

Rb[(Zr6C)Cl15] was prepared by heating ZrCl4, Zr powder, RbCl and Al4C3 at 850 °C for 21 days. The crystal structure was determined by single crystal X-ray diffraction (space group Pmma, a = 18.484(3), b = 18.962(2), c = 9.708(1) Å, V = 2505.4(6) Å3, and Z = 4). Rb[(Zr6C)Cl15] crystallises in the Cs[Nb6Cl15]-type structure. It is built up from two interconnected types of cluster chains, one with linear Zr−Cla−a-Zr bridges, the other one with bent bridges. The rubidium cations are spread over three different sites within the cluster network which differs significantly from the cation distribution in the comparable potassium and caesium phases. The cation distribution can be rationalised considering the size of the cavities and the Coulombic interactions.

scholarly journals Diffuse scattering from the lead-based relaxor ferroelectric PbMg1/3Ta2/3O3

2011 ◽  
Vol 44 (3) ◽  
pp. 603-609 ◽  
Author(s):  
Antonio Cervellino ◽  
S. N. Gvasaliya ◽  
O. Zaharko ◽  
B. Roessli ◽  
G. M. Rotaru ◽  
...  
Keyword(s):  
Single Crystal ◽  
Atomic Structure ◽  
Diffuse Scattering ◽  
Relaxor Ferroelectric ◽  
The Other ◽  
X Ray Diffraction ◽  
Correlation Lengths ◽  
X Ray ◽  
Displacement Vectors ◽  
Polar Nanoregions

The relaxor ferroelectric PbMg1/3Ta2/3O3was studied by single-crystal neutron and synchrotron X-ray diffraction, and its detailed atomic structure modelled in terms of static Pb displacements that lead to the formation of polar nanoregions. Similar to the other members of the Pb-based relaxor family like PbMg1/3Nb2/3O3or PbZn1/3Nb2/3O3the diffuse scattering in the [H00]/[0K0] scattering plane has a butterfly shape around theh00 Bragg reflections and is orthogonal to the scattering vector forhh0 peaks. In the [HH0]/[00L] plane the diffuse scattering is elongated along the 〈112〉 directions and is orthogonal to the scattering vector forhhhreflections. It is found that a model consisting of correlated Pb displacements along the 〈111〉 directions reproduces adequately the main features of the diffuse scattering in PbMg1/3Ta2/3O3when the correlation lengths between the Pb-ion displacement vectors are longest along the 〈111〉 and shortest along the 〈11{\overline 2}〉 and 〈1{\overline 1}0〉 directions.

Soluble Pyridine Complexes Of The Ternary Gallium(III) Chalcogenide Halides (GaEX)3, With E = S, Se And X = Cl, Br

2001 ◽  
Vol 56 (8) ◽  
pp. 711-718 ◽  
Author(s):  
Stefan D. Nogai ◽  
Annette Schier ◽  
Hubert Schmidbaur
Keyword(s):  
Single Crystal ◽  
Molecular Complexes ◽  
Membered Ring ◽  
New Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pyridine Ligands ◽  
Ring Molecules ◽  
Gallium Metal ◽  
Convenient Preparation

The four ternary gallium(III) chalcogenide halides GaEX with E = S, Se and X = Cl, Br can be prepared a) from the binary gallium(III) chalcogenides Ga2E3 and halides Ga2X6, b) from gallium(I) tetrahalogallates(III) GafGaX4] and the chalcogen E, and c) from gallium metal and the dichalcogen dihalides E2X2. The new method c) was shown to be the most convenient preparation. The products are readily soluble in pyridine to give trinuclear molecular complexes [GaEX·Py]3 which are not volatile without decomposition, but can be purified by crystallization. The structures have been determined by single crystal X-ray diffraction techniques. The two chlorides are isostructural and show twisted tub-form six-membered ring molecules with the pyridine donors in axial positions. The two bromides are also isostructural, but with the pyridine ligands in two axial and one equatorial positions

Dinuclear oxofluorometallates as a new structural type of d 0 transition metal oxofluoride compound

2012 ◽  
Vol 68 (6) ◽  
pp. 602-609 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Natalia M. Laptash
Keyword(s):  
Transition Metal ◽  
Single Crystal ◽  
Structural Type ◽  
The Other ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Orthorhombic Unit Cell ◽  
Fluoride Ions ◽  
X Ray ◽  
Irradiation Process

Five isomorphous d 0 transition metal oxofluoride compounds A 3[M 2O x F11 − x ]·(AF)0.333 (A = K, Rb, NH4; M = Nb, Mo, W; x = 2, 4) have been synthesized from acid fluoride solutions, and their crystal structures have been determined by single-crystal X-ray diffraction. The basic structural building units are dinuclear M 2 X 11 (dimers) formed from NbOF5 or Mo(W)O2F4 octahedra connected by the fluorine bridging atom. In the Nb2O2F9 dimer, the O atoms occupy apical corners. In the M 2O4F7 (M = Mo, W) dimers two O atoms are also apically placed, whereas the other two O atoms are statistically disordered in equatorial planes. The arrangement of dimers is so that the hexagonal tunnels containing `free' fluoride ions are formed. During the irradiation process the orthorhombic structure of K3Nb2O2F9·(KF)0.333 transforms into a pseudo-trigonal one with a = 23.15 Å, which is the [101] diagonal of the orthorhombic unit cell. The other four trigonal crystals are merohedral twins.

The perchlorotriphenylmethyl (PTM) radical

2013 ◽  
Vol 69 (3) ◽  
pp. 255-257 ◽  
Author(s):  
Judith Guasch ◽  
Xavier Fontrodona ◽  
Imma Ratera ◽  
Concepció Rovira ◽  
Jaume Veciana
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
The Other ◽  
X Ray Diffraction ◽  
Monoclinic Symmetry ◽  
Steric Strain ◽  
High Chemical ◽  
X Ray ◽  
Cl Atoms

In spite of the considerable understanding and development of perchlorotriphenylmethyl (PTM) radical derivatives, the preparation of crystals of the pure unsubstituted PTM radical, C19Cl15, suitable for single-crystal X-ray diffraction has remained a challenge since its discovery, and only two studies dealing with the crystal structure of the unsubstituted PTM radical have been published. In one study, the radical forms clathrates with aromatic solvents [Veciana, Carilla, Miravitlles & Molins (1987).J. Chem. Soc. Chem. Commun.pp. 812–814], and in the other the structure was determinedab initiofrom powder X-ray diffraction data [Rius, Miravitlles, Molins, Crespo & Veciana (1990).Mol. Cryst. Liq. Cryst.187, 155–163]. We report here the preparation of PTM crystals for single-crystal X-ray diffraction and their resolution. The structure, which shows monoclinic symmetry (C2/c), revealed a nonsymmetric molecular propeller conformation (D3symmetry) caused by the steric strain between theortho-Cl atoms, which protect the central C atom (sp2-hybridization and major spin density) and give high chemical and thermal persistence to the PTM. The supramolecular structure of PTM shows short Cl...Cl intermolecular interactions and can be described in terms of layers formed by rows of molecules positioned in a head-to-tail manner along thecaxis.

Molecular Cocrystals of Carboxylic Acids. XVII. Spectral Characterization of the Adducts of Triphenylphosphine Oxide With Substituted Phenoxyacetic Acids and the Crystal Structure of the 1 : 1 Adduct With (4-Chloro-2-methylphenoxy)acetic Acid

1994 ◽  
Vol 47 (7) ◽  
pp. 1401 ◽  
Author(s):  
DE Lynch ◽  
G Smith ◽  
KA Byriel ◽  
CHL Kennard ◽  
AK Whittaker ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Triphenylphosphine Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acid Proton ◽  
Phosphoryl Oxygen ◽  
Phenoxyacetic Acids ◽  
Dichlorophenoxy Acetic Acid ◽  
Molecular Adducts

A series of 1:1 molecular adducts of triphenylphosphine oxide ( tppo ) with substituted phenoxyacetic acids has been prepared and characterized by using infrared, solid-state 1H and 31P n.m.r. spectroscopy, and X-ray powder diffraction methods. The crystal structure of one of these, with the herbicidally active (4-chloro-2-methylphenoxy)acetic acid ( mcpa ),[( tppo )( mcpa )], has been determined by X-ray diffraction methods. This compound is isomorphous with the tppo adduct of (2,4-dichlorophenoxy)acetic acid. The title compound has two independent and different molecular adducts in the asymmetric unit each with strong hydrogen-bonding interactions between the carboxylic acid proton and the phosphoryl oxygen of tppo [O...O, 2.579, 2.647(9)Ǻ].

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