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Cis Positions (cis + position)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Gas-phase acidity of proline from density functional computations

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2001
T. Marino
Abstract Density functional computations using the B3LYP hybrid potential coupled with the extended 6-311++G** basis set were performed to evaluate gas-phase acidity of proline ,-amino acid. The computed value of gas-phase acidity is 1403.8 kJ/mol in good agreement with the experimental counterpart (1395.0±13.8 kJ/mol) and is referred to the deprotonated species deriving from the first relative minimum of neutral proline characterized by the exo ring conformation with the carboxyl group in cis position. The most stable neutral proline isomer gives rise to a species for which the gas-phase acidity value (1384.5 kJ/mol) is also close to the experimental data. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 264,268, 2001 [source]

Ethyl 3-[1-(5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorin-2-yl)propan-2-ylidene]carbazate: a combined X-ray and density functional theory (DFT) study

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010
Youssef Arfaoui
In the title compound, C11H21N2O5P, one of the two carbazate N atoms is involved in the C=N double bond and the H atom of the second N atom is engaged in an intramolecular hydrogen bond with an O atom from the dimethylphosphorin-2-yl group, which is in an uncommon cis position with respect to the carbamate group. The cohesion of the crystal structure is also reinforced by weak intermolecular hydrogen bonds. Density functional theory (DFT) calculations at the B3LYP/6-311++g(2d,2p) level revealed the lowest energy structure to have a Z configuration at the C=N bond, which is consistent with the configuration found in the X-ray crystal structure, as well as a less stable E counterpart which lies 2.0,kcal,mol,1 higher in potential energy. Correlations between the experimental and computational studies are discussed. [source]

Two cobalt(III) mono-dimethylglyoximates isolated from one reaction

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2010
Agnieszka Czapik
The reaction of cobalt(II) nitrate hexahydrate with dimethylglyoxime (DMGH2) and 1,10-phenanthroline (phen) in a 1:1:2 molar ratio results in two CoIII mono-dimethylglyoximates having two chelating phen ligands in cis positions and the CoIII atom coordinated by six N atoms in a distorted octahedral coordination geometry. The isolated products differ in the deprotonation state of the DMGH2 ligand. In [,-hydrogen bis(N,N,-dioxidobutane-2,3-diimine)]tetrakis(1,10-phenanthroline)cobalt(III) trinitrate ethanol disolvate 1.87-hydrate, [Co2(C4H6N2O2)(C4H7N2O2)(C12H8N2)4](NO3)3·2C2H6O·1.87H2O, (I), the C2 -symmetric cation is formed with the coordination [Co(DMG)(phen)2]+ cations aggregating via a very strong O,...H+...O, hydrogen bond with an O...O distance of 2.409,(4),Å. Crystals of (I) exhibit extensive disorder of the solvent molecules, the nitrate anions and one of the phen ligands. Compound (I) is a kinetic product, not isolated previously from similar systems, that transforms slowly into (N -hydroxy- N,-oxidobutane-2,3-diimine)bis(1,10-phenanthroline)cobalt(III) dinitrate ethanol monosolvate 0.4-hydrate, [Co(C4H7N2O2)(C12H8N2)2](NO3)2·C2H6O·0.40H2O, (II), with the DMGH, ligand hydrogen bonded to one of the nitrate anions. In (II), the solvent molecules and one of the nitrate anions are disordered. [source]

One-dimensional structure of catena -poly[tetraethylammonium [tetracyanoiron(III)-,-cyano-[bis(ethylenediamine)cadmium(II)]-,-cyano] tetrahydrate]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2006
Werner Massa
The title compound, {(C8H20N)[CdFe(CN)6(C2H8N2)2]·4H2O}n, was isolated from the aqueous system Cd2+/ethylenediamine (en)/[Fe(CN)6]3, in the presence of [Et4N]Br. The crystal structure is dominated by a one-dimensional motif, viz. a negatively charged 2,2-CT (cis,trans) [,Cd(en)2,NC,Fe(CN)4,CN,]nn, chain. The Cd and Fe atoms of the anion and the N atom of the cation all lie on twofold axes. The ethyl groups of the cation are equally disordered over two orientations. The cationic building block of the chain consists of a CdII atom coordinated by two chelating en ligands, and the distorted octahedral coordination is completed by two bridging cyano ligands in cis positions. The anionic building block is an [Fe(CN)6]3, anion in which the FeIII atom is octahedrally coordinated by six cyano ligands; two of the cyano ligands, in trans positions, are bridging. The uncoordinated water molecules link neighbouring chains through O,H,N and N,H,O hydrogen bonds. [source]

Crystallographic report: A synthetic precursor for hetero-binuclear metal complexes, [Ru(bpy)(dppy)2(CO)2](PF6)2 (bpy = 2,2,-bipyridine, dppy = 2-(diphenylphosphino)pyridine)

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2004
Dai Ooyama
Abstract In the title complex, [Ru(bpy)(dppy)2(CO)2](PF6)2 (bpy = 2,2,-bipyridine, dppy = 2-(diphenylphosphino)pyridine), the ruthenium atom exhibits a slightly distorted octahedral coordination with the carbonyl ligands in cis positions. In addition, two dppy ligands coordinate to the ruthenium center through the phosphorus atoms in mutually trans positions and two pyridyl nitrogen atoms of the dppy direct toward two carbonyl ligands. Copyright © 2004 John Wiley & Sons, Ltd. [source]

1-Methyl-1-phenyl-3-[1-hydroxyimino-2-(succinimido)ethyl]cyclobutane

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2004
Muharrem Dinçer
In the title compound, C17H20N2O3, the cyclobutane ring is puckered, with a dihedral angle of 19.11,(15)°. The 1-phenyl and 3-[1-hydroxyimino-2-(succinimido)ethyl] groups are in cis positions. The molecules are linked by O,H,O and C,H,,(benzene) interactions, forming a two-dimensional network. [source]

Ni(bipy)2Ni(CN)4, a new type of one-dimensional square tetracyano complex

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2000
Juraj, ernák
The one-dimensional structure of catena -poly[[bis(2,2,-bipyridyl-1,2N,N,)-,-cyano-1:2,2N:C -dicyano-2,2C -dinickel(II)]-,-cyano- C:N], [Ni2(CN)4(C10H8N2)2]n, consists of infinite zigzag chains running parallel to the c axis. The chains are composed of paramagnetic [Ni(bipy)2]2+ cations (bricks; nickel on a twofold axis) linked by diamagnetic [Ni(CN)4]2, anions (mortar; nickel on an inversion center) via bridging cyano groups. The bridging cyano groups occupy cis positions in the cation and trans positions in the anion, giving rise to a new previously unknown CT-type chain (i.e. cis,trans -type) among square tetracyano complexes. The coordination polyhedron of the paramagnetic Ni atom (twofold symmetry) is a slightly deformed octahedron with the two Ni,N(bipy) bonds in cis positions being somewhat longer [2.112,(3),Å] than the remaining four Ni,N bonds with a mean value of 2.065,(6),Å. The bond distances and angles in the anion have typical values. [source]