Investigation into aroylhydrazones as chelating agents. Part 3. Synthesis and spectroscopic characterization of complexes of Mn II , Co II , Ni II , Cu II , and Zn II with 2,6-diacetylpyridine bis(benzoylhydrazone) and X-ray structure of aquachloro[2,6-diacetylpyridine bis(benzoylhydrazone)]manganese(II) chloride

Abstract

The chelating behaviour of neutral and deprotonated 2,6-diacetylpyridine bis(benzoylhydrazone)(H2dapb) has been investigated in some new complexes of MnII, CoII, NiII, CuII, and ZnII. An X-ray diffraction analysis was carried out on [Mn(H2dapb)(OH2)Cl]Cl. The crystals are monoclinic, space group P21/c, with unit-cell dimensions a= 7.065(6), b=17.096(9), c=19.446(13)Å, β= 96.89(8)°, and Z= 4. The structure was solved by the heavy-atom technique from 1 545 observed independent reflections recorded at room temperature on an automated diffractometer and refined to a final R value of 0.0329. The structure consists of [Mn(H2dapb)(OH2)Cl]+ cations and Cl– anions. The cation has a pentagonal-bipyramidal geometry, with H2dapb forming the equatorial plane and the H2O and Cl groups occupying the axial positions. The i.r. spectra suggest differences in the interaction of these metals with the hydrazone molecule.