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Structural and Magnetic Properties of Co(II) Complexes with Tridentate ONO Pincer-Type Ligands

Veronika Chrenková *, Dušan Valigura

Institute of Chemistry, Faculty of Natural Sciences, University of SS. Cyril and Methodius, J. Herdu 2, Trnava, SK-917 01, Slovak Republic

E-mail: * veron.chrenkova@gmail.com

Abstract: Pincer type ligand 2,6-pyridinedimethanol was used as a useful tool in the preparation of the Co(II) pseudoctahedral complex together with 3,5-dinitrobenzoate counteranion. New complex of the composition [Co(pydm)2](3,5-dnbz)2 (pydm = 2,6-pyridinedimethanol, and 3,5-dnbz = 3,5-dinitrobenzoate anion) has been prepared and characterized. Its XRD structure revealed pseudooctahedral {CoN2O4} chromophore around the cobalt atom with Co—N distances significantly shorter (Co—Nav = 2.038 Ǻ) in comparison to the Co—O ones (Co—Oav = 2.142 Ǻ), which was probably the reason of its relatively high zero-field splitting parameter (D/hc = 43.6 cm–1). Positive value of the D parameter causes slow relaxation process typical for Co(II) SMM behavior. The 3,5-dinitrobenzoate counteranions are strongly bonded to the [Co(pydm)2] cation via rather strong hydrogen bonds (O∙∙∙Oav = 2.568 Ǻ) forming “quasi molecular” units. Solid state structure allowed different p-p stacking interactions of neighboring “molecular” unit aromatic rings probally leading to observation of the additional relaxation mode.

Keywords: cobalt(II) complex, pincer type ligand, 2,6-pyridinedimethanol, structure and magnetism

Full paper in Portable Document Format: acs_0296.pdf

Acta Chimica Slovaca, Vol. 11, No. 1, 2018, pp. 26—30, DOI: 10.2478/acs-2018-0005