Investigation into aroylhydrazones as chelating agents. Part 3. Synthesis and spectroscopic characterization of complexes of MnII, CoII, NiII, CuII, and ZnII 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 Mn^II, Co^II, Ni^II, Cu^II, and Zn^II. 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.