ChemInform Abstract: Syntheses and Crystal Structures of Two Novel Alkaline Uranyl Chromates A2(UO2)(CrO4)2(A: Rb, Cs) with Bidentate Coordination Mode of Uranyl Ions by Chromate Anions.

ChemInform ◽  
2012 ◽  
Vol 43 (20) ◽  
pp. no-no
Author(s):  
Oleg I. Siidra ◽  
Evgeny V. Nazarchuk ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structures ◽  
Coordination Mode ◽  
Uranyl Ions ◽  
Bidentate Coordination

ASSOCIATION OF URACIL WITH Zn2+ AND THE HYDRATED Zn2+: A DFT INVESTIGATION

2007 ◽  
Vol 06 (02) ◽  
pp. 197-212 ◽  
Author(s):  
NANA WANG ◽  
PING LI ◽  
YI HU ◽  
YUXIANG BU ◽  
WEIHUA WANG ◽  
...  
Keyword(s):  
Density Functional ◽  
Coordination Mode ◽  
Coordination Complexes ◽  
Carbonyl Oxygen ◽  
Water Molecules ◽  
Bidentate Coordination ◽  
Hydration Effect ◽  
The Density Functional Theory ◽  
Before And After ◽  
Monodentate Coordination

The association behaviors between Uracil and Zn 2+ in vacuum and in the presence of extra water molecules have been investigated systematically using the density functional theory (DFT). In these systems, the interaction of Zn 2+ with the carbonyl oxygen O 4 is systematically favored relative to O 2. For Uracil- Zn 2+ complexes, the more stable coordination mode among the possible complexes corresponds to the bidentate one, where the monodentate coordination mode is about 37 kcal/mol higher in energy relative to the bidentate case. Correspondingly, the stabilities of these structures are enhanced due to the formations of the four-membered chelate ring in the bidentate coordination processes. In the monodentate coordination complexes, the hydration effects are larger than those in the bidentate coordination complexes. The most basic center in the Uracil remains the same regardless of whether introducing the water molecules to Zn 2+ or not. The calculated Zn 2+ bonding energies in Uracil- Zn 2+( H 2 O ) complexes are reduced in comparison to those of the unhydrated Uracil- Zn 2+ complexes. Moreover, investigations of stepwise hydration of Zn 2+ in the most stable Uracil- Zn 2+ complex suggest that the successive hydration effect on the Zn 2+ site can enhance the strength of C = O bond in the Uracil- Zn 2+ complexes and reduce the association interaction of Uracil with Zn 2+. Additionally, the most acidic site of Uracil has been changed from N 1- to N 3– H group before and after introducing the Zn 2+ and there is a significant increase in the overall acidity of the system.

C-13 NMR Investigation of the Ph-Dependence of Copper(II) Complexation to Glucuronic-Acid

1986 ◽  
Vol 39 (9) ◽  
pp. 1307 ◽  
Author(s):  
IB Cook ◽  
RJ Magee ◽  
R Payne ◽  
B Ternai
Keyword(s):  
Aqueous Solution ◽  
Coordination Mode ◽  
Glucuronic Acid ◽  
Ph Dependence ◽  
Line Broadening ◽  
Bidentate Coordination ◽  
Differential Line ◽  
Ph Dependent

The interaction of paramagnetic copper(II) ions with glucuronic acid in aqueous solution was studied by differential line broadening analysis of carbon-13 n.m.r. spectra. Evidence is presented for pH-dependent complexation behaviour, with simple carboxylate complexation dominating below pH 4.5, and a more complicated bidentate coordination mode involving O 3 above pH 4.5.

New Coordination Polymers of Lanthanide(III) with Tetrazole-1-acetic Acid: Synthesis, Crystal Structures, and Magnetic Properties

2008 ◽  
Vol 61 (4) ◽  
pp. 303 ◽  
Author(s):  
Xiu-Qing Zhang ◽  
Qing Yu ◽  
He-Dong Bian ◽  
Shi-Ping Yan ◽  
Dai-Zheng Liao ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Coordination Polymers ◽  
Coordination Mode ◽  
Magnetic Measurements ◽  
Acid Synthesis ◽  
Antiferromagnetic Coupling ◽  
Bidentate Coordination ◽  
X Ray ◽  
X Ray Crystallography ◽  
Lanthanide Cations

New coordination polymers {[Ln(tza)3(H2O)2]·mH2O}n (Ln = LaIII 1 and PrIII 2, m = 2; Ln = NdIII 3, m = 1.5) and {[Sm2(tza)6(H2O)5]·H2O}n 4 (Htza = tetrazole-1-acetic acid) have been synthesized and characterized by IR spectroscopy, elemental analysis, X-ray crystallography, and magnetic measurements. The Htza ligand coordinates to the lanthanide cations through the carboxylate group in a monodentate, bridging bidentate coordination mode or bridging tridentate to two metal centres. Complexes 1 and 2 are isostructural. Complex 3 has a similar structure to 1 and 2, but the arrangement of ligands has changed. Complex 4 consists of two types of metallic molecules. Magnetic measurements show weak antiferromagnetic coupling between the metal centres in complexes 2 and 3.

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