N-salicylideneamino acidate complexes of oxovanadium(IV). Part 1. Crystal and molecular structures and spectroscopic properties

1994 ◽  
pp. 149 ◽  
Author(s):  
Isabel Cavaco ◽  
Jo�o Costa Pessoa ◽  
Dina Costa ◽  
Maria T. Duarte ◽  
Robert D. Gillard ◽  
...  
Keyword(s):  
Spectroscopic Properties ◽  
Molecular Structures ◽  
Crystal And Molecular Structures

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.

Gold-acetylide chemistry: the structure of the complex [Au2(μ-dppm) (C≡C—CMe3)2]

1995 ◽  
Vol 73 (1) ◽  
pp. 6-11 ◽  
Author(s):  
Nicholas C. Payne ◽  
Ravindranath Ramachandran ◽  
Richard J. Puddephatt
Keyword(s):  
Spectroscopic Properties ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Crystallography ◽  
Crystal And Molecular Structures ◽  
Cell Dimensions ◽  
Counter Data ◽  
Gold Acetylide

The complex [Au2(μ-dppm)(C≡Ct-Bu)2], 1, dppm=Ph2PCH2PPh2, is formed by reaction of [AuC≡Ct-Bu] with dppm. Compound 1, as an acetone solvate, crystallizes in the monoclinic space group P21/c with cell dimensions a = 14.047(1), b = 16.124(1), c = 17.140(3) Å, β = 103.17(2)° and four formula units per cell. The crystal and molecular structures of this salt were solved by X-ray diffraction techniques using 2634 counter data with I > 2σ(I). Refinement of 278 variables by full-matrix least squares converged at an agreement factor R = 0.023. Thermolysis of complex 1 in refluxing toluene led to intermolecular elimination of t-BuC≡CH, by combination of a t-BuC≡C ligand of one molecule of 1 with a proton from the CH2P2 group of a second, and formation of the stable tetragold(I) complex [Au4(μ3-Ph2PCHPPh2)(μ-dppm)(C≡Ct-Bu)3], 2, which was characterized by its spectroscopic properties. Keywords: acetylide complexes, gold complexes, X-ray crystallography, nmr spectroscopy, bis(diphenylphosphino)methane.

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
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