| Abstract
| - The complexes [Cu2(μ-Cl)2(Cl)2(L)2] (L = dialkylpyridine-2,6-dicarboxylate; R = Et, L = depc, 1; R = i-Pr, L =dppc, 2) have been prepared and their magnetic properties studied. The crystal structures of complexes 1 and 2have been solved. Compound 1 belongs to the P1̄ space group with Z = 2, a = 8.3020(10) Å, b = 9.2050(10)Å, c = 10.065(2) Å, α = 99.040(10)°, β = 100.810(10)°, and γ = 106.502(10)° whereas 2 belongs to the C2/cspace group with Z = 8, a = 11.6360(10) Å, b = 25.906(3) Å, c = 11.76579(10) Å, and β = 107.900(10)°. Thedifferent alkyl ester substitutes produce substantial structural and electronic differences. The Cu2Cl2 core geometryis planar for 1 whereas it adopts a butterfly shape in the case of 2. Furthermore, in 2 the dppc ligand coordinatesonly by the carbonyl oxygen atoms whereas in 1 the depc ligand coordinates through carbonyl and alkoxy oxygenatoms. Magnetic susceptibility data show a ferromagnetic coupling between the two Cu(II) centers in both cases(J = 39.9(6) cm-1 for 1, and J = 51.3(5) cm-1 for 2) with very weak antiferromagnetic interactions (J ‘ = −0.59cm-1 and −0.57 cm-1 for 1 and 2, respectively). Theoretical calculations at the extended Hückel level have alsobeen carried out to further understand the electronic nature of complexes 1 and 2.
- New dinuclear copper(II) complexes doubly bridged by chloro ligands, [Cu2(μ-Cl)2(Cl)2(L)2] (L = dialkylpyridine-2,6-dicarboxylate; R = Et, depc, 1; R = i-Pr, dppc, 2), have been prepared and structurally and magnetically characterized. In these two complexes, the simple ester substitution from ethyl to isopropyl produces substantial structural and electronic consequences that are chiefly manifested through their crystal structures and magnetic properties. In particular, the Cu metal centers in complex 1 display a very unusual type of coordination where the ester groups from the L ligand are weakly bonded alternately by carbonyl and alkoxy oxygen atoms.
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