Investigation into aroylhydrazones as chelating agents. Part 2. Neutral and deprotonated ligand behaviour of 2,6-diacetylpyridine bis-(picolinoylhydrazone) in complexes of MnII, CoII, NiII, and ZnII and X-ray structure of diaqua[2,6-diacetylpyridine bis(picolinoylhydrazonato)-(2–)]manganese(II)

Abstract

The co-ordinating properties of 2,6-diacetylpyridine bis(picolinoylhydrazone)(H₂dappc) have been investigated in some new complexes of Mn^II, Co^II, Ni^II, and Zn^II characterized by spectroscopic and magnetic techniques. An X-ray diffraction analysis was carried out on Mn(dappc)·9H₂O. The crystals are monoclinic, space group C2/c, with unit-cell dimensions a= 13.96(1), b= 15.25(2), c= 13.59(1)Å, β= 109.59(8)°, and Z= 4. A total of 1 161 observed reflections have been measured by single-crystal diffractometry and refined by full-matrix least squares to R= 0.050. The manganese ion is in a pentagonal-bipyramidal environment with the dappc ligand occupying the pentagonal girdle and two water molecules in the axial sites.