PENTAGONAL-BIPYRAMIDAL Mn(II) AND Zn(II) COMPLEXES WITH 2′,2′″-(2,6-PYRIDINDIYLDI-ETHYLIDENE)DIOXAMOHYDRAZIDE

ABSTRACT

[Mn(H₂dapsox)Cl(H₂O)]ClċH₂O (1) and Zn(H₂dapsox)-(H₂O)₂]Cl₂ċH₂O (2) were synthesized from 2,6-diacetylpyridine (dap), oxamic acid hydrazide (sox) and MnCl₂ċ4H₂O or ZnCl₂ċ2H₂O in 1:2:1 molar ratio, employing a template approach. Based on elemental analyses, molar conductivity and magnetic susceptibility data, IR, ¹H and ¹³C NMR and EA spectra, as well as thermal analyses (DSC and TG), a pentagonal-bipyramidal (PBP) geometry for the complexes was determined. Symmetrically coordinated 2′,2′″-(2,6-pyridindiyldiethylidene)dioxamohydrazide (H₂dapsox) is located as a pentadentate ligand in the equatorial plane. The stability of the 3d metal complexes having the PBP geometry is discussed. It was found that Co(II) and Mn(II) produce the most stable complexes of this type, while the Zn(II) complex of the same geometry is much less stable.

ACKNOWLEDGMENT

This work was supported by the Ministry for Science and Technology of the Republic of Serbia.