Semiconductor Alloys: Local Bond Lengths, Mixing Enthalpies, and Microclusters

1985 ◽  
Vol 46 ◽  
Author(s):  
A.B. Chen ◽  
A. Sher
Keyword(s):  
Statistical Theory ◽  
Bond Length ◽  
Local Structure ◽  
Theoretical Studies ◽  
Semiconductor Alloys ◽  
Bond Lengths ◽  
Random Alloy ◽  
Dilute Limit ◽  
Mixing Enthalpies

AbstractSeveral recent theoretical studies of the local structure of semiconductor alloys are summarized. First, dilute limit calculations of local bond lengths and mixing enthalpies are discussed. These calculations include effects due to both bond length and bondangle distortions, as well as local chemical rearrangements. Then, a new statistical theory of concentrated alloys is described. Deviations from random alloy distributions (microclusters) are predicted.

Structure of the Short-Lived Intermediate Formed during the Metal Substitution Reaction of the Mercury(II) Porphyrin Complex with Cobalt(II) Ion in Aqueous Solution Determined by the Stopped-Flow EXAFS Method

1998 ◽  
Vol 53 (4) ◽  
pp. 469-475 ◽  
Author(s):  
Kazuhiko Ozutsumi ◽  
Shintaro Ohnishia ◽  
Hitoshi Ohtaki ◽  
Masaaki Tabatab
Keyword(s):  
Bond Length ◽  
Local Structure ◽  
Substitution Reaction ◽  
Stopped Flow ◽  
Coordination Geometry ◽  
Metal Substitution ◽  
Octahedral Structure ◽  
Coordinate Structure ◽  
Bond Lengths ◽  
Additional Water

The local structure around the cobalt(II) ion in the reaction intermediate formed during the metal substitution reaction of the homodinuclear mercury(II) porphyrin (5,10,15,20-tetrakis(4- sulfonatophenyl)porphyrin; H2tpps4- ) complex with a cobalt(II) ion in an acetate buffer has been determined by the stopped-flow EXAFS method. The structure of the reactant and the product of the above reaction has also been determined by the same method. The coordination geometry around the cobalt(II) ion in the heterodinuclear intermediate, [Hg(tpps)Coll]2- , is six-coordinate octahedral with four additional water and/or acetate oxygen atoms. The Coll-N and Coll-O bond lengths in the intermediate are 212(2) and 221(1) pm, respectively. The product, [Coll(tpps)]4-, has a six-coordinate octahedral structure, the Coll-N and Coll-O bond lengths being 203(1) and 215(1) pm, respectively. The Coll-N bond length in the intermediate is ca. 9 pm longer than that in the product. The Coll-O bond length in the intermediate is also ca. 9 pm longer than that of 212(1) pm in the reactant, the cobalt(II) acetato complex, and ca. 6 pm longer than that in the product. The longer Coll-O bond in the intermediate as compared to those in the reactant and in the product appears to be responsible for the instability of the intermediate. The oxidized product, [Colll(tpps)]3-, has a six-coordinate structure with two additional Colll-O bonds. The Colll-N and Colll-O bond lengths are 189(1) and 197(2) pm, respectively, and are much shorter than those in [Coll(tpps)]4-.

scholarly journals Complex transition metal hydrides: linear correlation of countercation electronegativity versus T–D bond lengths

2015 ◽  
Vol 51 (56) ◽  
pp. 11248-11251 ◽  
Author(s):  
T. D. Humphries ◽  
D. A. Sheppard ◽  
C. E. Buckley
Keyword(s):  
Transition Metal ◽  
Bond Length ◽  
Linear Correlation ◽  
Metal Hydrides ◽  
Bond Lengths ◽  
Transition Metal Hydrides ◽  
Complex Hydrides

For homoleptic 18-electron complex hydrides, an inverse linear correlation has been established between the T–deuterium bond length and the average electronegativity of the metal countercations.

A Cd(ii)-based MOF as a photosensitive Schottky diode: experimental and theoretical studies

2017 ◽  
Vol 46 (34) ◽  
pp. 11239-11249 ◽  
Author(s):  
Shibashis Halder ◽  
Arka Dey ◽  
Aradhita Bhattacharjee ◽  
Joaquín Ortega-Castro ◽  
Antonio Frontera ◽  
...  
Keyword(s):  
Schottky Diode ◽  
Electronic Transition ◽  
Theoretical Studies ◽  
Bond Lengths ◽  
Current Conduction ◽  
Experimental And Theoretical Studies

A Cd(ii) based 2D MOF shows photosensitive Schottky diode character. Light of a certain wavelength changes some bond lengths within the MOF. This leads to the reduction in the energy needed for the allowed electronic transition showing enhanced current conduction.

Reaktionen von Azacoronanden mit Quecksilber(II)iodid: Kristallstrukturen zweier Komplexe von Hgl2 mit Diaza-15-krone-5 und Diaza-18-krone-6 /Reactions of Azacoronands with Mercury(II) Iodide: Crystal Structures of Two Complexes of Hgl2 with Diaza-15-crown-5, and Diaza-18-crown-6

1997 ◽  
Vol 52 (7) ◽  
pp. 847-850 ◽  
Author(s):  
Joachim Pickardt ◽  
Sven Wiese
Keyword(s):  
Bond Length ◽  
Crystal Structures ◽  
Iodine Atom ◽  
Bond Lengths ◽  
The Mean ◽  
Iodide Crystal

The reactions of diaza-15-crown-5 (“2.1”), and diaza-18-crown-6 (“2.2”), resp., with HgI2 in methanol afford the compounds [Hg(2.1)I][Hg2I6] (1) and [Hg(2.2)I][Hg2I6] (2), the crystal structures of which were determined. 1 consists of isolated cations [Hg(2.1)I]+ and anions [Hg2I6]2-. In the cations Hg is coordinated by one iodine atom, the two N atoms and the three O atoms of the ligand; the Hg-I distance is 262.1(3) pm, the Hg-N bond lengths are 221(2) and 238(2) pm; they are significantly shorter than the Hg-O distances, which are in the range between 262 and 271 pm. 2 consists of cations [Hg(2.2)I]+, which are bridged by the anions. In the cations of 2 Hg is coordinated by an iodine atom and by the two N atoms of the ligand, but by only three of the four O atoms. The Hg-I distance is 275.8(5) pm, the mean Hg-N bond length 234(4) pm, and the Hg-O distances vary between 285 and 304 pm. The Hg-I distance to the bridging I atom of the anion is 388.6(6) pm. The Hg-I bond lengths within the anions are slightly widened by this coordination.

Theoretical studies of the local structure and spin Hamiltonian parameters for Rh2+:ZnWO4

2014 ◽  
Vol 451 ◽  
pp. 80-83 ◽  
Author(s):  
Chang-Chun Ding ◽  
Shao-Yi Wu ◽  
Min-Quan Kuang ◽  
Yong-Kun Cheng ◽  
Li-Juan Zhang
Keyword(s):  
Local Structure ◽  
Theoretical Studies ◽  
Spin Hamiltonian ◽  
Hamiltonian Parameters

The Crystal and Molecular Structures of Bis(diethyldithiocarbamato)platinum(II) and Bis[di(2-hydroxyethyl)dithiocarbamato]platinum(II)

1992 ◽  
Vol 45 (2) ◽  
pp. 429 ◽  
Author(s):  
AT Baker ◽  
MT Emett
Keyword(s):  
Single Crystal ◽  
Bond Length ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Crystal And Molecular Structures

The structures of [Pt(S2CN(C2H5)2)2] (1) and [Pt(S2CN(C2H4OH)2)2] (2) have been determined by single-crystal X-ray diffractometry. Compound (1) crystallizes in the tetragonal space group P42/n, a 16.4692(10),c 6.2160(6) � (Z = 4); R was 0.029 for 1012 observed reflections. Compound (2) is monoclinic, space group Pc, a 6-0663(11), b 1.1784(15), c 12.5740(21) � ,β92.569(8)� (Z = 2); R was 0.019 for 1573 observed reflections. The presence of electron-withdrawing groups in the ligands of (2) appears to have little effect on the Pt-S distances but causes an increase in the C-N bond length, with the C-N bond lengths being significantly different at the 2 σ level.

Bond lengths in organic and metal-organic compounds revisited: X—H bond lengths from neutron diffraction data

2010 ◽  
Vol 66 (3) ◽  
pp. 380-386 ◽  
Author(s):  
Frank H. Allen ◽  
Ian J. Bruno
Keyword(s):  
Bond Length ◽  
Data Availability ◽  
General Level ◽  
Mean Values ◽  
Bond Lengths ◽  
Transition Metal Hydrides ◽  
Order Of Magnitude ◽  
Metal Organic ◽  
Structural Database ◽  
The Mean

The number of structures in the Cambridge Structural Database (CSD) has increased by an order of magnitude since the preparation of two major compilations of standard bond lengths in mid-1985. It is now of interest to examine whether this huge increase in data availability has implications for the mean bond-length values published in the late 1980s. Those compilations reported mean X—H bond lengths derived from rather sparse information and for rather few chemical environments. During the intervening years, the number of neutron studies has also increased, although only by a factor of around 2.25, permitting a new analysis of X—H bond-length distributions for (a) organic X = C, N, O, B, and (b) a variety of terminal and homometallic bridging transition metal hydrides. New mean values are reported here and are compared with earlier results. These new overall means are also complemented by an analysis of X—H distances at lower temperatures (T ≤ 140 K), which indicates the general level of librational effects in X—H systems. The study also extends the range of chemical environments for which statistically acceptable mean X—H bond lengths can be obtained, although values from individual structures are also collated to further extend the chemical range of this compilation. Updated default `neutron-normalization' distances for use in hydrogen-bond and deformation-density studies are also proposed for C—H, N—H and O—H, and the low-temperature analysis provides specific values for certain chemical environments and hybridization states of X.

P3Se4I: 5-Iodo-2,3,6,7-tetraselena-1,4,5-triphosphabicyclo[221]heptan, ein neues Phosphorselenaiodid / P3Se4I: 5-Iodo-2,3,6,7-tetraselena-1,4,5-triphosphabicyclo[221]heptan, a New Phosphorus Selena Iodide

1987 ◽  
Vol 42 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Roger Blachnik ◽  
Willi Buchmeier ◽  
Claudia Schneider ◽  
Ulrike Wickel
Keyword(s):  
Bond Length ◽  
Nmr Spectra ◽  
Lattice Parameters ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean

P3Se4I is formed by the reaction of molten P4Se3 and I2. P3Se4I is monoclinic, space group P21/c with the lattice parameters of a = 1130.3(3) pm, b = 654.5(2) pm, c =1420.5(4) pm, β - 117.64(2)°. d = 3.87 g cm-3 and dx = 3.82 g cm-3 for Z = 4. The structure of the molecule is derived from the structure of α-or β-P4Se3I2 by the substitution of a P−I group by a Se-atom. The P−I, P−P and Se−Se bond lengths are 249.9, 219.2 and 236.9 pm. resp. The mean P−Se bond length is 225.0 pm. The molecule is stabilized by two weak intramolecular P−Se and P−I bonds, comparable to the bonding situation in α-P4Se3I2 . The 31P NMR spectra reveal a coalescence effect, due to equilibrium between two isomeric forms of the molecules.

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