Pentagonal-bipyramidal Mn(II) and Zn(II) complexes with 2',2'''-(2,6-pyridindiyldi-ethylidene)dioxamohydrazide

[Mn(H(2)dapsox)Cl(H2O)](ClH2O)-H-. (1) and [Zn(H(2)dapsox)(H2O)(2)](Cl2H2O)-H-. (2) were synthesized from 2,6-diacetylpyridine (dap), oxamic acid hydrazide (sox) and MnCl(2)(.)4H(2)O or ZnCl(2)(.)2H(2)O in 1:2:1 molar ratio, employing a template approach. Based on elemental analyses, molar conductivity and magnetic susceptibility data, IR, H-1 and C-13 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 (H(2)dapsox) 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.