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Crystal Structure and Magnetic Properties of an Oxamato-Bridged Heterobimetallic Tetranuclear [(NiCuII)-Cu-II](2) Complex of the Rack Type

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Author(s):
Reis, Natalia V. ; Barros, Wdeson P. ; Oliveira, Willian X. C. ; Pereira, Cynthia L. M. ; Rocha, Willian R. ; Pinheiro, Carlos B. ; Lloret, Francesc ; Julve, Miguel ; Stumpf, Humberto O.
Total Authors: 9
Document type: Journal article
Source: European Journal of Inorganic Chemistry; v. N/A, n. 3-4, p. 8-pg., 2018-01-31.
Abstract

This work discusses a new heterobimetallic nickel(II)copper-(II) complex of the formula [Ni(tpa) Cu(opba)](2)center dot 6H(2)O (1) {H(4)opba = N, N'-1,2-phenylenebis(oxamic acid) and tpa = tris(2-pyridylmethyl)amine}. The molecular structure of 1 consists of neutral tetranuclear species with a 4R rack-type architecture featuring two (NiCuII)-Cu-II dinuclear units connected through two out-of-plane oxo(carboxylate-oxamate) atoms from the opba ligands. The crystal packing of 1 exhibits a supramolecular 1D arrangement of tetranuclear entities connected by hydrogen bonds and pi-pi stacking interactions. The dc magnetic properties of 1 were interpreted according to its dimer-of-dimer structure; the spin Hamiltonian being defined as {H = -J[S-Ni1 center dot S-Cu1 + S-Ni1i center dot S(Cu1)i - j(eff)(S-Cu1 center dot S-Cu1i)]}. The analysis of the magnetic data shows the occurrence of a strong intradimer antiferromagnetic coupling between the Ni-II and Cu-II ions [J = -115.2(4) cm(-1)] and a weak interdimer antiferromagnetic coupling between the Cu-II ions [j(eff) = -1.12(7) cm(-1)]. DFT-type calculations were performed to visualize the exchange pathway through the oxamate bridge and substantiate the value of J. (AU)

FAPESP's process: 15/22379-7 - Multifunctional molecular magnetic systems: synthesis and study of magnetic, luminescent and photorreactive properties of polinuclear complexes containing transition and lanthanide metal ions
Grantee:Wdeson Pereira Barros
Support Opportunities: Regular Research Grants