Complexes of iron(II),iron(III) and zinc(II) with condensation derivatives of 2-acetylpyridine and oxalic or malonic dihydrazide.Crystal structure of tris[(l-(2-pyridyl)ethylidene)hydrazine]iron(II) perchlorate

摘要

Complexes of zinc and iron with N',N'2-bis[(lE)-l-(2-pyridyl)ethylidene]ethanedihydrazide (H_2L1) and N',N'~2-bis[(lE)-l-(2-pyridyl)ethylidene]propanedihydrazide (H_2L2) were prepared.Zn~(II) complexes with both ligands have an octahedral geometry.In the complex of Zn~(II) with H_2L1,the ligand is coordinated as a tridentate species in the monoanionic form,building two five-membered rings around Zn~(II).Three remaining coordination sites are occupied by water molecules,and in the outer sphere there is a ClO_4~- ion.In the other Zn11 complex,the H_2L2 ligand is coordinated in the enol form as a tetradenate species,forming a five-memebered,a six-membered and a seven-membered ring,the remaining coordination sites being occupied by water molecules,while in the outer sphere there are two ClO_4~- ions.The Fe~(III) complex with H_2L2 is a high-spin octahedral complex.The ligand is coordinated in the enol form,in a tetradentate fashion via pyridine and hydrazone nitrogens.The remaining two coordination sites in the complex are occupied by water molecules and a Cl~- ion,and in the outer sphere there are two Cl~ anions.The octahedral Fe~(III) complex obtained from the reaction of FeCl_3 centre dot 6H_2O and H_2L1 in absolute ethanol has the formula [Fe(HLl)Cl_2(H_2O)] centre dot 1.5H_2O.However,during coordination of the H_2L1 ligand to Fe~(III) in water,oxidative degradation of the side chain (-CO-CO-) and reduction of Fe~(III) to Fe~(II) occurs,affording octahedral tris(l-(2-pyridyl)ethylidenehydrazine] iron" perchlorate,as confirmed by X-ray structure analysis.