Stereochemical Consequences of the Bismuth Atom Electron Lone Pair, a Comparison between MX6E and MX6Systems. Crystal and Molecular Structures of Tris[N-(P,P-diphenylphosphinoyl)-P,P-diphenylphosphinimidato]bismuth(III), [Bi{(OPPh2)2N}3], -indium(III), [In{(OPPh2)2N}3]·C6H6, and -gallium(III), [Ga{(OPPh2)2N}3]·CH2Cl2

1996 ◽  
Vol 35 (13) ◽  
pp. 3948-3953 ◽  
Author(s):  
Verónica García-Montalvo ◽  
Raymundo Cea-Olivares ◽  
Daniel J. Williams ◽  
Georgina Espinosa-Pérez
Keyword(s):  
Lone Pair ◽  
Molecular Structures ◽  
Bismuth Atom ◽  
Crystal And Molecular Structures

scholarly journals Synthesis, Characterization and Molecular Structures of some Bismuth(III) Complexes with Thiosemicarbazones and Dithiocarbazonic Acid Methylester Derivatives with Activity against Helicobacter Pylori

1995 ◽  
Vol 2 (5) ◽  
pp. 271-292 ◽  
Author(s):  
Rolf Diemer ◽  
Uwe Dittes ◽  
Bernhard Nuber ◽  
Volker Seifried ◽  
Wolfgang Opferkuch ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Coordination Sphere ◽  
Sulfur Atom ◽  
Central Atom ◽  
Lone Pair ◽  
Bidentate Ligand ◽  
Molecular Structures ◽  
Ligand Molecule ◽  
Bismuth Atom ◽  
Chlorine Atoms

The reactions of bismuth(III) nitrate pentahydrate and bismuth(III) chloride with heterocyclic thiosemicarbazones and derivatives of dithiocarbazonic acid methylester were used to synthesize the respective bismuth(III) complexes, which could be divided into five groups D-H because of their stoichiometrical properties and their molecular structures. The molecular structure and the near coordination sphere of the bismuth(III) central atom of four representative compounds were determined by single-crystal X-ray studies. Bis[1-azepanyl-4-(2-pyridyl)-2,3-diazapenta-1,3-diene-1-thiolato-N′,N3,S]bismuth(III) nitrate (5) belongs to group D. The two tridentate ligands and the nitrate ion surround the bismuth atom. The best description of the coordination sphere appears to be that of a distorted trigonal dodecahedron with one position occupied by the lone pair of the bismuth atom. Bis[1-azepanyl-4-(2-thienyl)-2,3-diazapenta-1,3-diene-1-thiolato-N3,S]bismuth(III) nitrate (9) is assigned to complex type E. Here, two deprotonated ligand molecules are coordinated to the bismuth(III) central atom as bidentate ligands. The structure of this complex can best be described as a distorted trigonal antiprism with a five-coordinated central atom. The two triangular faces are formed by the atoms S(4), N(6), O(11) and S(3), N(4) and the lone pair of the central atom. The two chelate rings are almost perpendicular to each other. Complex molecules of group F form dimeric units with bichloro-bridged bismuth atoms. The structure of di-μ-chlorobis[1-azepanyl-4-(2-pyridyl)-2,3-diazapenta-1,3-diene-1-thiolato-N′,N3,S-chloro]dibismuth(III) (15) can be described as two six-coordinated bismuth atoms, which are bound together via two bridging chlorine atoms. The two bismuth atoms Bi(1) and Bi(1a) and the two bridging chlorine atoms Cl(2) and Cl(2a) form the Bi2Cl2 plane. The two tridentate ligand molecules coordinate via the same atoms as shown in complex 5. In addition, they form two parallel planes, which are perpendicular to the Bi2Cl2 plane. With regard to the center of the Bi(1)-Bi(2) axis they are central point symmetrical, i.e. one pyridine ring lies above and the other beneath the Bi2Cl2 plane. Bismuth(III) chloride and pyridine-2-carboxaldehydethiosemicarbazone 1 b or 2-acetylpyridine-thiosemicarbazone 1 c form complexes of group G. Three chlorine atoms and a bidentate ligand are coordinated to the bismuth(III) central atom. The bidentate ligand bound to the central atom through the N(3) atom and the sulfur atom of the thioketo group. The structure of 18 is completely different from the structures of the bismuth(III) complexes discussed so far and was therefore assigned to group H. The bismuth central atom is coordinated with two ligands, which are bound in different ways. One of them is deprotonated. This ligand is bound to the central atom via the sulfur atom S(3) of the thiolate group and the N(5) atom. An interaction between the sulfur atom of the thiophene ring and the bismuth atom is not possible.The other ligand molecule is not deprotonated. This ligand is bound to the bismuth(III) cation merely via the sulfur atom S(1) of the thioketo group. The best description of the coordination sphere of the bismuth atom is that of a distorted square bipyramidal polyhedron. The square face is formed by the atoms S(3), N(5), Cl(1), the lone pair and the bismuth atom within. The axial positions are occupied by the atoms S(1) and Cl(2). The bond angle between S(1), Bi(1) and Cl(2) differs by about eight degrees from the value determined for a regular square bipyramidal polyhedron of 180 degrees.Some of the newly synthesized bismuth complexes and three ligands have been tested against several strains of Helicobacter pylori bacteria in an agar dilution test. Almost all of the listed bismuth complexes show excellent inhibitory properties with regard to growth of H. pylori already at low concentrations.

The crystal and molecular structures of the ligand (E)-Pyridine-2-carbaldehyde Pyridin-2'-ylhydrazone and the palladium(II) complex Chloro[(E)-pyridine-2-carbaldehyde pyridin-2'-ylhydrazonato]palladium(II) which involves the coordination of the ligand in its anionic form

1984 ◽  
Vol 37 (4) ◽  
pp. 739 ◽  
Author(s):  
AT Casey ◽  
BF Hoskins ◽  
IP Traverso
Keyword(s):  
Least Squares Method ◽  
Complex Structure ◽  
Lone Pair ◽  
Unit Cell ◽  
Molecular Structures ◽  
Thermal Parameters ◽  
Anionic Form ◽  
Hydrogen Atoms ◽  
Space Group ◽  
Crystal And Molecular Structures

The crystal and molecular structures of the ligand (E)-pyridine-2-carbaldehyde pyridin-2'-ylhydrazone hydrate and its complex chloro[(E)-pyridine-2-carbaldehyde pyridin-2'-ylhydrazonato]palladium(II) have been determined by single-crystal three-dimensional X-ray diffraction techniques. Crystals of the ligand are monoclinic with space group P 21/c. The unit cell, which contains four molecules of ligand together with approximately ten disordered water molecules, has the dimensions a 17.762(4), b 3,8717(11), c 18.503(4) Ǻ and β 107.99(2)°. Crystals of the complex are triclinic with space group P1, and the unit cell has the dimensions a 6.9721(3), b 9.0739(11), c 9.1304(9) Ǻ, α81.116(9), β 88.778(8) and γ 81.392(8)°; Z = 2. The ligand structure was solved by direct methods and refined with anisotropic thermal parameters for all non-hydrogen atoms and isotropic thermal parameters for hydrogen and solvent atoms. The complex structure was solved by conventional Fourier methods and refined with anisotropic thermal parameters for all non-hydrogen atoms. A full-matrix least-squares method was employed for both structures based on 1295 and 2224 statistically significant reflections giving final values of R 0.061, Rw 0.068 and R 0.028, Rw 0.030 for the ligand and complex respectively. The structure analysis of the ligand shows definite evidence of delocalization of lone pair electrons in the hydrazine moiety. The ligand in its anionic form coordinates in a tridentate manner to the palladium atom in the complex through the two pyridine nitrogen atoms and the distal nitrogen of the hydrazine residue. A square-planar array is formed by a chlorine atom occupying the fourth position. Molecular dimensions suggest that the lone pair on the proximal nitrogen is delocalized over the entire molecule. Standard valence-bond and 'increased valence' methods have been applied in order to determine resonance schemes consistent with the observed structures of both the ligand and its complex.

Cis-trans-Isomere von Diazadiphosphetidin-Derivaten: Fünf Kristall- und Molekülstrukturen / Cis-trans Isomers of Diazadiphosphetidine Derivatives: Five Crystal and Molecular Structures

1979 ◽  
Vol 34 (2) ◽  
pp. 256-261 ◽  
Author(s):  
Siegfried Pohl
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Lone Pair ◽  
Molecular Structures ◽  
Trans Isomers ◽  
Mean Values ◽  
X Ray ◽  
Crystal And Molecular Structures

AbstractThe crystal structures of the compounds [R3CP(X)NR]2(R= CH3; X=S, Te for cis isomers and X= lone pair, S, Te for trans isomers) (2-6) were determined from single crystal X-ray data. The four-membered P-N rings in the cis isomers 2 and 3 show significant deviations from planarity attributed to steric overcrowding in the molecules.The trans isomers 4-6 are planar. The P-N bond lenghts (mean values for 2-6:171.4, 170, 171.6, 169.2 and 168.3 pm)in the cis isomers are not significantly different from the corresponding lengths in the trans isomers 5 and 6.

The Solid State Conformation of Diaryl Ditellurides and Diselenides: The Crystal and Molecular Structures of (C4H3E2)2E'2 (E = O, S; E' = Te, Se)

2000 ◽  
Vol 55 (5) ◽  
pp. 361-368 ◽  
Author(s):  
Raija Oilunkaniemi ◽  
Risto S. Laitinen ◽  
Markku Ahlgrén
Keyword(s):  
Solid State ◽  
Lone Pair ◽  
Spectroscopic Properties ◽  
Molecular Structures ◽  
Dihedral Angles ◽  
Single Bond ◽  
Aromatic Rings ◽  
Bond Lengths ◽  
Crystal And Molecular Structures ◽  
Solid State Conformation

The crystal and molecular structures of dithienyl ditelluride (C4H3S)2Te2 (1), difuryl ditelluride (C4H3O)2Te2 (2), dithienyl diselenide (C4H3S)2Se2 (3), and difuryl diselenide (C4H3O)2Se2 (4) are reported in this paper and compared to those of other simple diaryl ditellurides and diselenides. The chalcogen-chajcogen bonds exhibit approximately single bond lengths [Te-Te = 2.7337(8) and 2.7240(4) Å in 1 and 2, respectively; Se-Se = 2.357(1) and 2.368(2) Å in 3 and 4, respectively], as do the chalcogen-carbon bond lengths [Te-C = 2.095(9) - 2.104(6) in 1 and 2.091(6) - 2.105(9) Å in 2; Se-C = 1.87(1) - 1.90(1) Å in 3 and 1.887(8) - 1.897(10) Å in 4]. The aromatic rings are disordered. The dihedral angles C-E-E-C range from 79(2) to 96(1)° are consistent with the concept of minimized p lone-pair repulsion of adjacent chalcogen atoms. The dependence of molecular parameters on the angle between the aromatic rings and the chalcogen-chalcogen bonds follow trends established previously for aromatic disulfides. Though the bond parameters and conformations of 1 - 4 are similar, the packing of the molecules is different. The two ditellurides 1 and 2 show short Te···Te contacts (3.900 - 4.002 Å in 1 and 4.060 - 4.172 Å in 2). The two diselenides 3 and 4 do not exhibit close chalcogen-chalcogen interactions. The NMR spectroscopic properties of 1 - 4 are discussed.

A Solvent-Dependent and Electrochemically Controlled Self-Assembling/Disassembling System

2003 ◽  
Vol 68 (9) ◽  
pp. 1647-1662 ◽  
Author(s):  
Valeria Amendola ◽  
Massimo Boiocchi ◽  
Yuri Diaz Fernandez ◽  
Carlo Mangano ◽  
Piersandro Pallavicini
Keyword(s):  
Equilibrium Mixture ◽  
Bidentate Ligand ◽  
Molecular Structures ◽  
The Self ◽  
Molar Ratio ◽  
Crystal And Molecular Structures ◽  
Self Assembling ◽  
Irreversible Oxidation ◽  
Irreversible Reduction ◽  
Metal Ligand

The bis-bidentate ligand R,S-1,2-diphenyl-N,N'-bis(2-quinolinemethylidene)ethane-1,2-diamine (ligand 4), containing two (iminomethyl)quinoline moieties separated by a cis-1,2-diphenylethylene spacer, forms stable complexes with both CuI and CuII. With CuII, the monomeric 1:1 complex [CuII(4)]2+ is obtained both in CH3CN and CH2Cl2. With CuI and overall 1:1 metal/ligand molar ratio, an equilibrium mixture is obtained in CH3CN, consisting of [CuI(4)2]+, [CuI2(4)2]2+ and [CuI2(4)(CH3CN)4]2+. The preponderant species is the two-metal one-ligand "open" complex [CuI2(4)(CH3CN)4]2+, in which each Cu+ cation is coordinated in a tetrahedral fashion by one (iminomethyl)quinoline unit and by two CH3CN molecules. Precipitation from the equilibrium mixture yields only crystals of [CuI2(4)(CH3CN)4](ClO4)2·2CH3CN, whose crystal and molecular structures have been determined. On the other hand, in the poorly coordinating CH2Cl2 solvent, only the dimeric helical [CuI2(4)2]2+ complex is obtained, when the overall metal/ligand 1:1 molar ratio is chosen. Addition of large quantities of acetonitrile to solutions of [CuI2(4)2]2+ in dichlorometane results in the formation of [CuI2(4)(CH3CN)4]2+, i.e. in the solvent-driven disassembling of the CuI helicate. While electrochemistry in CH3CN is poorly defined due to the presence of more than one CuI species, cyclic voltammetry experiments carried out in CH2Cl2 revealed a well defined behavior, with irreversible oxidation of [CuI2(4)2]2+ and irreversible reduction of [CuII(4)]2+ taking place at separate potentials (∆E ≈ 700 mV). Irreversibility and separation of the redox events are due to the self-assembling and disassembling processes following the reduction and oxidation, respectively.

Synthesis of Trispirocyclotriphosphazenes with Oxaphosphorine Rings and Their Crystal and Molecular Structures

2021 ◽  
Vol 60 (7) ◽  
pp. 5014-5020
Author(s):  
Yuji Tada ◽  
Atsushi Sunada ◽  
Riki Watanabe ◽  
Makoto Kanazawa ◽  
Keiichiro Utsumi
Keyword(s):  
Molecular Structures ◽  
Crystal And Molecular Structures
Sign in / Sign up

Export Citation Format

Share Document