Search results for "Bond length"

Experimental and theoretical studies of the molecular and crystal structures of trialkoxy- and chlorodialkoxy-stibanes

2001

The molecular structures of triisopropoxystibane, Sb((OPr)-Pr-i)(3), and chlorodiisopropoxystibane, SbCl((OPr)-Pr-i)(2), were determined in the solid state by single crystal X-ray diffraction. Sb((OPr)-Pr-i)(3) forms discrete centrosymmetric dimers in the solid state via Sb . . .O-Sb interactions, leading to pseudo trigonal bipyramidal configurations of the four co-ordinate Sb atoms, while SbCl((OPr)-Pr-i)(2) forms chains via Sb . . .O-Sb and Sb . . . Cl-Sb bridges, resulting in five-co-ordinate Sb atoms with pseudo octahedral configurations. Comparison of the solid state structures and the density functional optimized molecular structures of Sb(OMe)(3), SbCl(OMe)(2) and their dimers reveal…

Octahedral distortion caused by hydrogen bonding in tris(diethylammonium) hexachloridoantimonate(III).

2010

The factors influencing the distortion of inorganic anions in the structures of chloridoantimonates(III) with organic cations, in spite of numerous structural studies on those compounds, have not been clearly described and separated. The title compound, [(C(2)H(5))(2)NH(2)](3)[SbCl(6)], consisting of isolated distorted [SbCl(6)](3-) octahedra that have C(3) symmetry and [(C(2)H(5))(2)NH(2)](+) cations, unequivocally shows the role played by hydrogen bonding in the geometry variations of inorganic anions. The organic cations, which are linked to the inorganic substructure through N-H...Cl hydrogen bonds, are clearly responsible for the distortion of the octahedral coordination of Sb(III) in …

Analysis of the CIPSI/DCCI approach to characterize the HF AND F2 single bond

1990

Abstract The aim of the present work is to account for the main differential correlation contributions occurring during the bond breaking process of HF and F2 molecules in an accurate and inexpensive way. Starting from the dissociation-consistent configuration interaction (DCCI) scheme by Goddard and co-workers the corresponding contributions are evaluated within the framework reported by Malrieu and co-workers, namely configuration interaction by perturbation with multiconfigurational zeroth-order wavefunction selected by iterative process (CIPSI). In addition, the DCCI scheme has been improved by introducing the dispersion effects associated with the valence MOs adjacent to the bond. The …

Theoretical Characterization of the Electronic Structure of Poly(Heteroaromatic Vinylenes)

1990

Since the pioneering work of the mid-seventies, the number of organic π-conjugated polymers, that can be made highly conducting upon appropriate chemical treatment, has grown tremendously. Among the most studied of these compounds are those based on fivemembered heteroaromatic rings, such as polythiophene (PT) and polypyrrole (PPy). The attractiveness of these polymers, relative to polyacetylene (PA) and poly(p-phenylene) (PPP), is the high chemical and thermal stability they show.1

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.

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…

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.

Coexistence of Mobile and Localized Electrons in Bis(ethylene)dithiotetrathiafulvalene(BEDT-TTF) Radical Salts with Paramagnetic Polyoxometalates: Sy…

1994

Influence of Structural Isomerism on the Electronic Properties of Extended Phthalocyanines

1993

Abstract The electronic structure of isomeric naphthalocyanines (H2Nc) is investigated using the nonempirical valence effective Hamiltonian (VEH) technique. The way the outer benzene rings are annelated (linearly as in 2,3-H2Nc or angularly as in 1,2-H2Nc) is shown to determine very important changes in the electronic properties. While similar properties to those of phthalocyanine are calculated for 1,2-H2Nc, lower oxidation potentials and red-shifted optical absorptions are predicted for 2,3-H2Nc in agreement with experimental data. The isomerism resulting from the different relative positions of the angularly annelated benzene rings in 1,2-H2Nc is shown to have almost no effect on the ele…

High-resolution Fourier transform infrared spectroscopy and analysis of the ν3 fundamental band of P4

1999

Abstract We present the first high-resolution infrared absorption study of the ν 3 fundamental of white phosphorus, P 4 . This spectrum has been analyzed using the STDS (Spherical Top Data System) software. The band center lies at 466.286 cm −1 . With the approximation ( Bζ ) 3 =− B 0 /2, we found that the ground-state bond length is r 0 =219.58 pm. This value is consistent with that of ab initio studies reported previously but significantly different from a value obtained from a Raman study.