Synthesis, X-ray crystal structure and magnetic properties of oxalate-bridged copper(II) complexes with 2,3-bis(2-pyridyl)pyrazine, 2,3-bis(2-pyridyl)quinoxaline and 2,2’-bipyrazine as peripheral ligands
Carranza, José Grove, Hilde Sletten, Jorunn Lloret, Francesc Julve, Miguel Kruger, Paul E. Eller, Chad Rillema, D. Paul
Carranza, José
Grove, Hilde
Sletten, Jorunn
Lloret, Francesc
Julve, Miguel
Kruger, Paul E.
Eller, Chad
Rillema, D. Paul
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2004-12
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copper,magnetic properties,N ligands,oxalate
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Carranza, José; Grove, Hilde; Sletten, Jorunn; Lloret, Francesc; Julve, Miguel; Kruger, Paul E.; Eller, Chad; Rillema, D. Paul. 2004. Synthesis, X-ray crystal structure and magnetic properties of oxalate-bridged copper(II) complexes with 2,3-bis(2-pyridyl)pyrazine, 2,3-bis(2-pyridyl)quinoxaline and 2,2’-bipyrazine as peripheral ligands. European Journal of Inorganic Chemistry, v.2004, no.24 pp.4836-4848
Abstract
Five oxalate-containing copper(ii) complexes of formula [Cu(dpq)(H2O)(ox)]·5H2O (1), [Cu(dpp)(H2O)(ox)]·H2O (2), [Cu(bpz)(ox)]n (3), [Cu2(dpp)2(H2O)2(NO3)2(ox)]·4H2O (4) and [Cu2Cl2(bpz)2(H2O)2(ox)][Cu(bpz)(H2O)2(ox)]·2H2O (5) [dpq = 2,3-bis(2-pyridyl)quinoxaline; dpp = 2,3-bis(2-pyridyl)pyrazine; bpz = 2,2′-bipyrazine; ox = oxalate] were prepared and their structures were determined by X-ray diffraction on single crystals. Complexes 1 and 2 are discrete mononuclear complexes with oxalate and dpq (1)/dpp (2) acting as bidentate ligands. Complex 3 is a neutral oxalato-bridged (2,2′-bipyrazine)copper(ii) chain where the oxalate adopts a bidentate/monodentate coordination mode, whereas 4 is an oxalato-bridged copper(ii) dinuclear complex with ox and dpp acting as bis-bidentate and bidentate ligands, respectively. The structure of 5 contains neutral [Cu(bpz)(H2O)2(ox)] (mononuclear) and [Cu2(bpz)2(H2O)2Cl2(ox)] (dinuclear) units where the bpz acts as a bidentate ligand and the oxalate group adopts the bidentate (mononuclear) and bis-bidentate (dinuclear) coordination modes. The copper atoms have distorted square pyramidal (1 and 2) and elongated octahedral (3−5) geometries: two nitrogen atoms from heterocyclic N-donors and two oxalate-oxygen atoms occupy the equatorial positions (1−5) and a water molecule (1 and 2), two oxalate-oxygen atoms (3), a water molecule and a nitrate-oxygen (4), and either two water molecules (5), mononuclear) or a chlorine atom and a water molecule (5, dinuclear) fill the axial ones. Magnetic susceptibility measurements for 3−5 in the temperature range 1.9−290 K reveal the occurrence of weak (J = −1.4 cm−1, 3) and strong (−312 and −345 cm−1 for 4 and 5, respectively; Hˆ = −J·SˆA·SˆB) antiferromagnetic interactions between the copper(ii) atoms in agreement with the out-of-plane (3) and in-plane (4 and 5) exchange pathways involved.
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Wiley
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European Journal of Inorganic Chemistry;v.2004, no.24