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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
chemistry
Anion influence on the structure and magnetic properties of a series of multidimensional pyrimidine-2-carboxylato-bridged copper(II) complexes
Inorganic Chemistry, Volume 47, No. 18, Year 2008
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Description
Seven new polynuclear copper(II) complexes of formula [Cu(μ-pymca) 2] (1) (pymca- = pyrimidine-2-carboxylato), [Cu(μ-pymca)Br] (2), [Cu(μ-pymca)CI] (3), [Cu(μ-pymca)(SCN)(H 2O)]·4H2O (4), [Cu(μ-pymca)N3] (5), [Cu2(μ1,5-dca)2(pymca)2] (6) (dca = dicyanamide), and K{[μ-Au(CN)2]2[(Cu(NH 3)2)2(μ-pymca)]}[Au(CN)2] 2 (7) have been synthesized by reactions of K-pymca with copper(II) ions in the presence of different counteranions. Compound 1 is a linear neutral chain with a carboxylato bridging ligand in a syn-anti coordination mode, whereas complexes 2 and 3 consist of cationic linear chains with cis and trans bis(chelating) pymca bridging ligands. Complex 4 adopts a helical pymca-bridged chain structure. In complex 5, zigzag pymca-bridged chains are connected by double end-on azide bridging ligands to afford a unique honeycomb layer structure. Complex 6 is a centrosymmetric dinuclear system with double μ1,5-dicyanamide bridging ligands and pymca end-cap ligands. Complex 7 is made of pymca-bridged dinuclear [Cu(NH3) 2(μ-pymca)Cu(NH3)2]3+ units connected by [Au(CN)2]- anions to four other dinuclear units, giving rise to cationic (4,4) rectangular nets, which are linked by aurophilic interactions to afford a singular 3D network. Variable-temperature magnetic susceptibility measurements show that complex 1 exhibits a very weak antiferromagnetic coupling through the syn-anti (equatorial-axial) carboxylate bridge (J = -0.57 cm-1), whereas complexes 2-4 and 7 exhibit weak to strong antiferromagnetic couplings through the bis(chelating) pymca bridging ligand (J = -17.5-276.1 cm-1). Quantum Monte Carlo methods have been used to analyze the experimental magnetic data for 5, leading to an antiferromagnetic coupling (J = -34 cm-1) through the pymca ligand and to a ferromagnetic coupling (J = 71 cm-1) through the azide bridging ligands. Complex 6 exhibits a very weak antiferromagnetic coupling through the dicyanamide bridging ligands (J = -5.1 cm-1). The magnitudes of the magnetic couplings in complexes 2-5 have been explained on the basis of the overlapping between magnetic orbitals and DFT theoretical calculations. © 2008 American Chemical Society.
Authors & Co-Authors
Suárez-Varela, José
Spain, Granada
Universidad de Granada
Mota, Antonio J.
Spain, Granada
Universidad de Granada
Aouryaghal, Hakima
Morocco, Tetouan
Faculté Des Sciences de Tétouan
Cano, Joan
Spain, Barcelona
Universitat de Barcelona
Rodríguez-Diéguez, Antonio
Spain, Granada
Universidad de Granada
Luneau, Dominique
France, Villeurbanne
Laboratoire Des Multimatériaux et Interfaces
Colacio, Enrique
Spain, Granada
Universidad de Granada
Statistics
Citations: 59
Authors: 7
Affiliations: 4
Identifiers
Doi:
10.1021/ic800625w
ISSN:
00201669