scholarly journals Studies of azo and azoxy dyestuffs. Part 17. Synthesis and structure determination of isomeric α and β phenylazoxypyridines, N-oxides, and methiodides. A reexamination of the oxidation of phenylazopyridines and X-ray structure analyses of 4-(phenyl-α-azoxy)pyridinium methiodide and 4-(phenyl-β-azoxy)pyridine-N-oxide

1984 ◽  
Vol 62 (8) ◽  
pp. 1628-1639 ◽  
Author(s):  
E. Buncel ◽  
S. R. Keum ◽  
M. Cygler ◽  
K. I. Varughese ◽  
G. I. Birnbaum
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Inductive Effect ◽  
Heavy Atom ◽  
Direct Methods ◽  
X Ray ◽  
Proton Donors ◽  
Structure Determinations ◽  
Heavy Atom Method

In an extension of Wallach rearrangement studies into the phenylazoxypyridine series, an investigation of 4-, 3-, and 2-phenylazoxypyridines, the N-oxides, and methiodides is reported. Oxidation of 4- and 3-phenylazopyridine with peracetic acid gives rise to the α and β phenylazoxypyridine-N-oxides, contrary to previous literature reports on the obtention solely of the α isomers. 2-Phenylazopyridine, however, yields only the 2-(phenyl-α-azoxy)pyridine-N-oxide. These results are rationalized on the basis of field, resonance, and steric effects. An unprecedented reactivity difference has been observed in the reactions of the α,β isomers of phenylazoxypyridines under conditions of the Wallach rearrangement. This reactivity difference permits the isolation of the α-azoxy isomers from the α,β mixtures. Unequivocal confirmation of the structures has been obtained from X-ray crystal structure determinations of two representative compounds in this series, viz. 4-(phenyl-β-azoxy)pyridine-N-oxide (11) and 4-(phenyl-α-azoxy)pyridinium methiodide (12), which itself was formed by deoxygenation of 4-(phenyl-α-azoxy)pyridine-N-oxide, followed by methylation with methyl iodide. The crystal structure of 11 was solved by direct methods and refined by block-diagonal least squares to R = 0.041 for 2479 observed reflections. The asymmetric unit contains two independent molecules, both of which are planar. The structure of 12 was determined by the heavy-atom method and refined by full-matrix least squares to R = 0.043 for 1718 observed reflections. The molecules are not planar, the pyridine ring being rotated by 36.5° from the phenylazoxy plane. Evidence is presented for the existence of intramolecular [Formula: see text] and [Formula: see text] bonds in crystal structures of trans-azoxyarenes. The carbon atoms involved in these hydrogen bonds are ortho to the azoxy group and can act as proton donors as a result of the inductive effect of the adjacent nitrogen.

Crystal structure of o-Phenanthrolinebis(thiourea)copper(I) iodide o-phenanthroline: Stereochemistry of [M(bidentate)(unidentate)2] coordination

1977 ◽  
Vol 30 (9) ◽  
pp. 1955 ◽  
Author(s):  
SR Hall ◽  
DL Kepert ◽  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Title Compound ◽  
Direct Methods ◽  
X Ray Diffraction ◽  
Coordination Type ◽  
X Ray ◽  
Phenanthroline Ligand

The crystal structure of the title compound, [Cu{CS(NH2)2}2(phen)] I,phen, has been determined by X-ray diffraction with direct methods, and refined by least squares to a residual of 0.043 for 5383 ?observed? reflections. Crystals are triclinic, Pī, a 13.263(8), b 12.449(2), c 10.214(2) Ǻ, α 113.20(2), β 90.16(2), γ 112.72(2)�, Z 2. The coordination about the copper is pseudo-tetrahedral, distorted by the bite of the phenanthroline ligand [Cu-S, 2.295(2), 2.280(1) Ǻ; Cu-N, 2.072(4), 2.089(5) Ǻ, N-Cu-N, 81.0(2)�; S-Cu-S, 117.31(6)�; N-Cu-S, 107.7(11)-117.23(9)�]. In addition the structure provides the first example of the determination of the geometry of the uncoordinated o- phenanthro-line molecule. The stereochemistry of the [M(bidentate)(unidentate)2] coordination type is considered in terms of a repulsion model.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

The crystal structure of diamminesilver dinitroargentate, [Ag(NH3)2]Ag(NO2)2*

1977 ◽  
Vol 146 (4-6) ◽  
Author(s):  
H. M. Maurer ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Heavy Atom ◽  
Anisotropic Temperature ◽  
Light Atoms ◽  
Difference Fourier ◽  
Temperature Factors ◽  
Heavy Atom Method ◽  
Silver Atoms ◽  
Block Diagonal

AbstractThe crystal structure of diamminesilver dinitroargentate, [Ag(NHThe point positions of the silver atoms were obtained by the heavy-atom method whereas those of the light atoms were found by difference Fourier syntheses. Coordinates and anisotropic temperature factors were refined by block-diagonal least-squares methods with the result

Crystal structure of cis-Tetracarbonylbis(chloromercury)iron

1976 ◽  
Vol 29 (9) ◽  
pp. 1905 ◽  
Author(s):  
CL Raston ◽  
AH White ◽  
SB Wild
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Diffraction Data ◽  
Title Compound ◽  
Direct Methods ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Independent Molecules

The crystal structure of the title compound has been determined by direct methods from X-ray diffraction data and refined by least squares to a residual of 0.071 for 2647 'observed' reflections. Crystals are monoclinic, C2/c, a = 36.81(1), b = 11.181(2), c = 20.369(5) �, β = 95.28(3)�, Z = 32. There are four independent molecules in the asymmetric unit, all with the cis disposition of ligands (<Fe-Hg), 2.498 �; <Hg-Fe-Hg), 80.9�); in one of the molecules one of the carbonyl sites is occupied by a more substantial moiety, possibly a result of partial occupancy of HgCl as a result of disorder or decomposition.

scholarly journals The reaction of 3,5-diphenyl-1,2-dithiolium-4-olate with aniline: the crystal structure of 1-phenylimino-2-phenylamino-3-phenylindene

1987 ◽  
Vol 65 (12) ◽  
pp. 2830-2833 ◽  
Author(s):  
David M. McKinnon ◽  
Peter D. Clark ◽  
Robert O. Martin ◽  
Louis T. J. Delbaere ◽  
J. Wilson Quail
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

3,5-Diphenyl-1,2-dithiolium-4-olate (1) reacts with aniline to form 1-phenylimino-2-phenylamino-3-phenylindene (3a). Under suitable conditions, 6-phenylbenzo[b]indeno[1,2-e]-1,2-thiazine is also formed. These structures are confirmed by alternative syntheses. The molecular structure of 3a has been determined by single crystal X-ray diffraction. Compound 3a crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.777(3) Å, b = 6.130(3) Å, c = 31.327(3) Å, 3 = 99.59(1)°, and Z = 8. The structure was solved by direct methods and refined by least squares to a final R = 0.055. The molecular structure of 3a shows the three phenyl containing substituents to have the planes of their ring systems tilted between 40° and 60° from the plane of the indene system due to steric repulsions.

An X-ray structural examination of an intermediate from the cleavage of a vic-diol by iodine(I) acetate

1980 ◽  
Vol 33 (3) ◽  
pp. 671 ◽  
Author(s):  
PG Beckingsale ◽  
JM Waters ◽  
TN Waters
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Structural Examination ◽  
Space Group ◽  
X Ray

The crystal structure of a compound isolated after reaction of iodine(1) acetate with cis-cyclohexane-1,2-diol has been determined by direct methods. It is identified as 2,2'-(butane-1,4-diyl)bis(hexahydro-1,3-benzodioxole). Crystals are orthorhombic, a 8.625(2), b 7.589(1), c 26.187(5) Ǻ, space group Pbca, Z 4. Least- squares refinement brought R to 0.046.

Crystal and Molecular Structure of Dithiocyanato(triphenylarsine)mercury(II)

1975 ◽  
Vol 53 (22) ◽  
pp. 3383-3387 ◽  
Author(s):  
Joseph Hubert ◽  
André L. Beauchamp ◽  
Roland Rivest
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Coordination Number ◽  
Diffraction Data ◽  
Crystal And Molecular Structure ◽  
Heavy Atom ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heavy Atom Method

The crystal and molecular structure of dithiocyanato(triphenylarsine)mercury(II) has been determined from X-ray diffraction data. The crystals are monoclinic, space group P21/c, with a = 10.290(7), b = 21.199(23), c = 10.719(7) Å, β = 112.00(2)°, and Z = 4. The structure has been solved by the heavy-atom method and refined by block-diagonal least-squares calculations. The agreement factor R obtained for 2607 'observed' reflections is 0.030. The crystal consists of single molecules. The 'characteristic' coordination number of mercury is three, with two sulfur and one arsenic atoms at the apexes of a triangle. The nitrogen atoms of the thiocyanate groups are at 2.67 and 2.74 Å from the adjoining mercury atoms and therefore link the different molecules together.

Crystal Structure of Adeninium Trichloromercurate(II),

1975 ◽  
Vol 53 (15) ◽  
pp. 2345-2350 ◽  
Author(s):  
Monique Authier-Martin ◽  
André L. Beauchamp
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Title Compound ◽  
Heavy Atom ◽  
Chloride Ions ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
Space Group ◽  
Heavy Atom Method

The title compound belongs to space group P21/c with a = 23.99(1), b = 4.245(2), c = 25.98(1) Å, β = 117.58(7)°, and Z = 8. The structure was solved by the heavy-atom method and refined by block-diagonal least squares on 2589 independent observed reflections. All non-hydrogen atoms were refined anisotropically and some of the hydrogen atoms were located but their parameters were not refined. The final values of R and Rw were 0.042 and 0.047, respectively.The two nonequivalent mercury atoms have very similar environments. Two short Hg—Cl bonds (2.34–2.38 Å) at ∼ 165° define a quasi-molecular HgCl2 unit. Overall octahedral coordination is completed with two chloride ions at 2.76–2.84 Å and two chlorine atoms at 3.19–3.26 Å on neighboring HgCl2 quasi-molecules. HgCl6 octahedra share edges to form twofold ribbons in the b direction. This pattern of octahedra is identical with the onereported for β-NH4HgCl3. The cations are pairs of N(1)-protonated adenine molecules linked by two N(10)—H(10)… N(7) hydrogen bonds and stacked in the b direction. Water molecules act as acceptors in moderately strong hydrogen bonds with acidic protons H(1) and H(9) of adeninium ions. Other generally weaker hydrogen bonds exist between the various parts of the structure.

The determination of crystal structure of chromium(II) phosphite dihydrate, CrHPO3 2 H2O

1987 ◽  
Vol 52 (7) ◽  
pp. 1742-1747 ◽  
Author(s):  
Jiří Brynda ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová
Keyword(s):  
Crystal Structure ◽  
Heavy Atom ◽  
Cross Linking ◽  
Unit Cell Parameters ◽  
Orthorhombic Space Group ◽  
Interatomic Distances ◽  
Reliability Factor ◽  
Cell Parameters ◽  
Heavy Atom Method

The crystal structure of CrHPO3.2 H2O has been solved by the heavy atom method. The compound crystallizes in the orthorhombic space group P212121 with the unit cell parameters a = 679·25(8), b = 915·61(8), c = 752·2(1) pm, Z = 4. The structure was refined to the final reliability factor R = 0·043 for 1 040 observed reflexions (I > 1·96σ(I)). The structure consists of chains formed by CrO6 octahedra connected each other in vertices. The chains are interconnected by phosphite tetrahedra HPO3. Hydrogen bridges of water-phosphite tetrahedron and water-water types form space cross-linking of the whole structure. Bond distances Cr-O in the tetragonally distorted octahedron range from 201·2 to 304·9 pm. The interatomic distances P-O in phosphite tetrahedron are between 152·1 and 152·7 pm. The degree of the distorsion DISQ of HPO3 tetrahedron and CrO6 octahedron is discussed on the basis of known structures of phosphites and chromium(II) compounds.

Ring contraction of 4-substituted 2,6-dichlorophenols. The crystal structure of 2,2,4α,5α-Tetrachloro-1α,3α-dihydroxycyclopentane-1,4-carbolactone

1977 ◽  
Vol 30 (10) ◽  
pp. 2195 ◽  
Author(s):  
RM Christie ◽  
RW Rickards ◽  
KJ Schmalzl ◽  
D Taylor
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Major Product ◽  
X Ray Diffraction ◽  
Ring Contraction ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Counter Data

Alkaline chlorination of the 4-alkyl-2,6-dichlorophenols (2b) and (2c) proceeds through ring contraction and halolactonization to form the 4α- alkyl-2,2,5α-trichloro-1α,3α-dihydroxycyclopentane-1,4-carbolactones (4b) and (4c). Under similar conditions, 2,4,6-trichlorophenol affords the analogous 2,2,4α,5α-tetrachloro-1α,3α-dihydroxycyclopentane-1,4- carbolactone (4a) in low yield, in addition to the Hantzsch acid (3a) as the major product. The acid (3a) upon further treatment undergoes chloro-lactonization to give the lactone (4a). The structures of the lactones (4b) and (4c) follow from spectroscopic comparison with (4a), the structure of which has been established by X-ray diffraction (C6H4Cl4O4 orthorhombic a 13.485(1), b 12.348(1), c 11.371(1) Ǻ, space group Pccn, Z 8, solved by direct methods and refined by block-diagonal and full-matrix least squares to R 0.031, Rw 0.043 for 1313 unique counter data with I/σ(I) ≥ 3.0).

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