Investigation into aroylhydrazones as chelating agents. Part 4. Synthesis and spectroscopic characterization of CoII, NiII, CuII, and ZnIIcomplexes of 2,6-diacetylpyridine bis(2-thenoylhydrazone) and X-ray crystal structure of bis[2,6-diacetylpyridine bis(2-thenoylhydrazonato)(2–)]dizinc(<scp>II</scp>)

Some new complexes of CoII, NiII, CuII, and ZnII with 2,6-diacetylpyridine bis(2-thenoylhydrazone)(H2dapt) have been synthesized and examined by i.r. Spectroscopy. The structure of Zn2(dapt)2 has been established by X-ray diffraction. Crystals are monoclinic, space group C2/c, with unit-cell dimensions a= 20.780(3), b= 17.162(2), c= 15.173(1)A,β= 48.85(1)&#176;, and Z= 4. The structure has been solved by the heavy-atom method and refined by full-matrix least-squares calculations to R= 0.0587 for 2119 diffractometer data. The compound is dimeric with the pyridine ring unusually bridging two zinc atoms, which have a highly distorted octahedral co-ordination. The deprotonated ligand is not planar, the hydrazone side chains being considerably twisted out of the plane of the pyridine ring.