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Issue 16, 2013
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Copper(II) assembling with bis(2-pyridylcarbonyl)amidate and N,N′-2,2-phenylenebis(oxamate)

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We herein present the synthesis and X-ray structures of five copper(II) complexes of formulae [Cu(bpca)(CF3SO3)(H2O)]·H2O (1), [Cu(bpca)(Phpr)(H2O)]·3/2H2O (2), {[Cu(bpca)]2[Cu(opba)(H2O)]}·H2O (3), {[Cu(bpca)]2(H2opba)}2·6H2O (4) and [Cu(bpca)(EtH2opba)]n (5), where bpca = bis(2-pyridylcarbonyl)amidate, Phpr = 3-phenylpropionate, CF3SO3 = triflate (anion of the trifluoromethanesulphonic acid), H4opba = N,N′-1,2-phenylenebis(oxamic acid), and EtH3opba = monoethyl ester derivative of the H4opba. 1 and 2 are mononuclear copper(II) complexes where the copper atom is five-coordinate in distorted square pyramidal surroundings with a tridentate bpca and a water molecule (1)/carboxylate oxygen (2) building the basal plane and a triflate oxygen (1)/water molecule (2) filling the apical position. 3 is a neutral tricopper(II) complex where the [Cu(opba)(H2O)]2− unit acts as a bis-bidentate ligand toward two peripheral [Cu(bpca)]+ fragments. The three crystallographically independent copper(II) ions in 3 are five-coordinate with two nitrogen and two oxygen atoms (inner copper atom)/three bpca-nitrogen and an oxamate oxygen (outer copper atom) building the basal plane plus a water molecule (inner copper)/an oxamate oxygen (outer copper) in the apical position (inner copper atom) of somewhat distorted square pyramidal surroundings. 4 is a centrosymmetric tetracopper(II) compound where four [Cu(bpca)]+ fragments are assembled by two H2opba2− groups adopting an unusual bidentate/bis-monodentate bridging mode. The two crystallographically independent copper(II) ions in 4 are also five-coordinate having the three bpca-nitrogens in basal positions, the other two sites of the distorted square pyramid being filled by two oxygens of either a bidentate oxamate (at one copper centre) or two bis-monodentate oxamates (at the other copper atom). 5 is a zigzag chain of [Cu(bpca)(H2O)]+ units which are connected through the EtH2opba ligand adopting a bidentate/monodentate bridging mode across the monodeprotonated oxamate group. Each copper(II) ion in 5 is six-coordinate in an elongated octahedral CuN3O3 chromophore. The magnetic properties of 3–5 were investigated in the temperature range 1.9–300 K. 3 exhibits an intermediate intramolecular antiferromagnetic interaction [J = −65.8(2) cm−1 with the Hamiltonian H = −J(SCu1·SCu2 + SCu2·SCu3)] which leads to a low-lying spin doublet at low temperatures. A weak antiferromagnetic coupling between the inner copper(II) ions occurs in 4 [J = −2.36(2) cm−1, H = −JS1·S2)] and a very small intrachain antiferromagnetic interaction is observed in 5 [J = −0.17(1) cm−1 with H = −JiSi·Si+1]. These values are analyzed by means of simple orbital symmetry considerations and compared with those previously reported for parent systems.

Graphical abstract: Copper(ii) assembling with bis(2-pyridylcarbonyl)amidate and N,N′-2,2-phenylenebis(oxamate)

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Publication details

The article was received on 08 Dec 2012, accepted on 10 Feb 2013 and first published on 11 Feb 2013

Article type: Paper
DOI: 10.1039/C3DT32949F
Citation: Dalton Trans., 2013,42, 5778-5795
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    Copper(II) assembling with bis(2-pyridylcarbonyl)amidate and N,N′-2,2-phenylenebis(oxamate)

    T. R. G. Simões, R. V. Mambrini, D. O. Reis, M. V. Marinho, M. A. Ribeiro, C. B. Pinheiro, J. Ferrando-Soria, M. Déniz, C. Ruiz-Pérez, D. Cangussu, H. O. Stumpf, F. Lloret and M. Julve, Dalton Trans., 2013, 42, 5778
    DOI: 10.1039/C3DT32949F

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