Cobalt(III), zinc(II), cadmium(II) and palladium(II) complexes with the hydrolysed and non-hydrolysed condensation products of 2-acetylpyridine with ethyl hydrazinoacetate: X-ray structure analysis of mer-bis{(E )-2-[N′-(1-pyridin-2-yl-ethylidene)hydrazino] acetato}cobalt(III) tetrafluoroborate

Four Co(III), Zn(II), Pd(II) and Cd(II) complexes with ligands derived in situ from acetylpyridine and ethyl hydrazinoacetate or hydrolysed ethyl hydrazinoacetate were prepared. An X-ray structural analysis showed that the Co(III) complex is octahedral with two tridentate (E)-2-[N′-(1-pyridin-2-yl-ethylidene)hydrazino]acetate (apha) ligands, each forming two five-membered rings with the metal ion. In the tetrahedral Zn(II) complex, only a single apha ligand was coordinated, in the same way as that in the Co(III) complex. In the case of the tetrahedral Cd(II) complex the non-hydrolysed form of (E)-2-[N′-(1-pyridin-2-yl-ethylidene)hydrazino]acetic acid ethyl ester (aphaoet) coordinated as a bidentate and the two remaining coordination sites were occupied by Cl− and CH3COO− ions. In addition, the square-planar neutral Pd(II) complex was synthesized, having the same bidentate as in the Cd(II) complex and two Cl− ions in the remaining coordination sites. Due to their being diamagnetic, all four complexes were ...