Insertion of a Water Oxygen Atom into a Phosphorus−Metal Bond:  From a P-Coordinated (Diphenylphosphino)alkyne to a Coordinated η2(O,C)-Vinyldiphenylphosphine Oxide†

1998 ◽  
Vol 17 (15) ◽  
pp. 3394-3397 ◽  
Author(s):  
Elmostafa Louattani ◽  
Isabel Moldes ◽  
Joan Suades ◽  
Joan F. Piniella ◽  
Angel Alvarez-Larena
Keyword(s):  
Oxygen Atom ◽  
Metal Bond ◽  
Water Oxygen ◽  
Water Oxygen Atom

Three Crystal Structures of Terephthalic Acid Salts of Simple Amines

2009 ◽  
Vol 64 (7) ◽  
pp. 865-870 ◽  
Author(s):  
Peter G. Jones ◽  
Jerzy Ossowski ◽  
Piotr Kus ◽  
Ina Dix
Keyword(s):  
Oxygen Atom ◽  
Crystal Structures ◽  
Terephthalic Acid ◽  
Inversion Symmetry ◽  
Supramolecular Synthons ◽  
Twofold Axis ◽  
Water Oxygen ◽  
Water Oxygen Atom ◽  
Acid Salts

Diphenethylamine forms two adducts (1 : 1, 1a and 2 : 1, 1b) with terephthalic acid (H2TPA). The former is bis(diphenethylammonium)H2TPA・TPA2− and the latter is bis(diphenethylammonium) ・TPA2−. The amine cis-2,6-dimethylpiperidine forms a hydrated 2 : 1 adduct, bis(2,6-dimethylpiperidinium) ・TPA2−・H2O (2). The crystal structures of all three compounds were determined. All H2TPA and TPA2− residues display inversion symmetry, while the water oxygen atom of 2 lies on a twofold axis. Packing analyses have identified some supramolecular synthons known from related structures.

A study of twinning in YBa2Cu3O7−x by large-angle convergent-beam electron diffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 20-21
Author(s):  
P.A. Midgley ◽  
R. Vincent ◽  
D. Cherns
Keyword(s):  
Electron Diffraction ◽  
Oxygen Atom ◽  
Strain Field ◽  
Large Angle ◽  
Convergent Beam Electron Diffraction ◽  
Orthorhombic Distortion ◽  
Beam Electron ◽  
Resultant Powder ◽  
Convergent Beam ◽  
Mesh Grid

The oxygenation of YBa2Cu3O7−x (YBCO) leads to an orthorhombic distortion of the unit cell to accommodate the extra oxygen atom. This makes the formation of twins energetically favourable with CuO4 planar unit chains running alternately along the a and b axes of the parent tetragonal structure. The geometry of this twinning is such that four possible twin variants may co-exist with the twin boundaries lying in the (110) or (110) planes of the deformed structure. The traces of these planes are not mutually perpendicular and thus the crystal is strained to allow for the mismatch. It is to the nature of this strain field that this work has been addressed.Sintered samples were prepared by crushing and dispersing the resultant powder onto a very fine Cu mesh grid. Single crystals were chemically thinned to perforation. No discernible artefacts were seen and similar results were obtained with either method.

Fast oxygen atom facility for studies related to low earth orbit activities

1992 ◽  
Author(s):  
G. CALEDONIA ◽  
R. KRECH ◽  
B. UPSCHULTE ◽  
D. SONNENFROH ◽  
D. OAKES ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Low Earth Orbit ◽  
Earth Orbit

Theoretical Studies of High Energy Oxygen Atom Chemistry

2004 ◽  
Author(s):  
M. Braunstein ◽  
J. Duff ◽  
R. Shroll ◽  
L. Bernstein ◽  
S. Adler-Golden
Keyword(s):  
Oxygen Atom ◽  
High Energy ◽  
Theoretical Studies ◽  
Atom Chemistry

Conformation and electronic structure of aromatic chloroformates

1987 ◽  
Vol 52 (4) ◽  
pp. 970-979 ◽  
Author(s):  
Otto Exner ◽  
Pavel Fiedler
Keyword(s):  
Electronic Structure ◽  
Oxygen Atom ◽  
Strong Interaction ◽  
Electron Distribution ◽  
Room Temperature ◽  
Functional Group ◽  
Dipole Moments ◽  
Carbonyl Oxygen ◽  
Nonpolar Solvents ◽  
Single Method

Aromatic chloroformates Ib-Ie were shown to exist in the ap conformation, in agreement with aliphatic chloroformates, i.e. the alkyl group is situated cis to the carbonyl oxygen atom as it is the case in all esters. While 4-nitrophenyl chloroformate (Ie) is in this conformation in crystal, in solution at most several tenths of percent of the sp conformation may be populated at room temperature and in nonpolar solvents only. A new analysis of dipole moments explained the previous puzzling results and demonstrated the impossibility to determine the conformation by this single method, in consequence of the strong interaction of adjoining bonds. If, however, the ap conformation is once proven, the dipole moments reveal some features of the electron distribution on the functional group, characterized by the enhanced polarity of the C-Cl bond and reduced polarity of the C=O bond. This is in agreement with the observed bond lengths and angles.

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