F-Element/crown ether complexes. 4. Synthesis and crystal and molecular structures of [MCl(OH2)2(18-crown-6)]Cl2.2H2O (M = samarium, gadolinium, terbium)

1987 ◽  
Vol 26 (10) ◽  
pp. 1498-1502 ◽  
Author(s):  
Robin D. Rogers ◽  
Lynn K. Kurihara
Keyword(s):  
Crown Ether ◽  
Molecular Structures ◽  
Crystal And Molecular Structures ◽  
Crown Ether Complexes

The crystal and molecular structures of two isostructural complexes: [(H3O•18-crown-6)2(ZnCl4)] and [(H3O•18-crown-6)2(MnCl4)]

1990 ◽  
Vol 68 (6) ◽  
pp. 797-803 ◽  
Author(s):  
Robert Chênevert ◽  
Daniel Chamberland ◽  
Michel Simard ◽  
François Brisse
Keyword(s):  
Crown Ether ◽  
Molecular Structures ◽  
The Other ◽  
Tetrahedral Coordination ◽  
Monoclinic System ◽  
Crystal And Molecular Structures ◽  
Hydronium Ion ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Ether Molecule

New macrocycle polyether 18-crown-6 complexes of stoichiometry [(H3O+•18-crown-6)2(MC42−)] have been synthesized for M = Zn and Mn. The two complexes are isostructural and crystallize in the monoclinic system, space group C2/c. The unit cell dimensions are as follows: a = 16.229(9), b = 11.535(3), c = 20.134(8) Å, β = 97.55(4)° and a = 16.255(6), b = 11.625(3), c = 20.122(8) Å, β = 96.54(3)° for the Zn and Mn complexes respectively. In both crystal structures (final Rw = 0.048 with 1817 reflections for Zn and Rw = 0.074 with 728 reflections for Mn), the crown ether molecule and the H3O+ cation to which it is hydrogen-bonded are disordered over two sites. The MCl42− anions, which have tetrahedral coordination, are on crystallographic twofold axes of rotation. The Mn—Cl and Zn—Cl distances average 2.270 and 2.361 Å respectively. The hydronium cation, H3O+, has pyramidal coordination. Of the two disordered crown ether molecules in the Zn and the Mn complexes, one has a slightly deformed (ttg)6 conformation while the other one may be described as having the distorted (ttg)5(ttc) conformation. These observations are in agreement with the infrared analyses of the complexes. Keywords: 18-crown-6 complexes, hydronium ion, ZnCl42−, MnCl42−, crystal structure.

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.

scholarly journals Pyrroloquinoline Quinone Aza‐Crown Ether Complexes as Biomimetics for Lanthanide and Calcium Dependent Alcohol Dehydrogenases

2021 ◽  
Author(s):  
Violeta A. Vetsova ◽  
Katherine R. Fisher ◽  
Henning Lumpe ◽  
Alexander Schäfer ◽  
Erik K. Schneider ◽  
...  
Keyword(s):  
Crown Ether ◽  
Pyrroloquinoline Quinone ◽  
Alcohol Dehydrogenases ◽  
Calcium Dependent ◽  
Crown Ether Complexes ◽  
Aza Crown Ether

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

The crystal and molecular structures of 3,3,6,6-Tetramethylbicyclo[2.2.1]heptane-2,5-dione and 6,6-Dibromo-1,3,3-Trimethylbicyclo[2.2.2] octane-2,5-dione

1982 ◽  
Vol 12 (4) ◽  
pp. 351-362 ◽  
Author(s):  
Romolo Faggiani ◽  
Colin James Lyne Lock ◽  
Nick Henry Werstiuk ◽  
Shahin Yeroushalmi
Keyword(s):  
Molecular Structures ◽  
Crystal And Molecular Structures
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