Synthesis and X-ray structure of a macrocyclic pentagonal bipyramidal complex of cobalt(II)

Abstract

Condensation of 2,9-di(1-methylhydrazino)-1,10-phenanthroline with 2,6-pyridinedicarbaldehyde in the presence of Co^II ions leads to the isolation in high yield of the seven-co-ordinate complex [Co(L¹)(H₂O)₂]²⁺. The X-ray structure of the hexafluorosilicate salt has been determined. The cobalt atom is coplanar with the five-co-ordinated nitrogens of the macrocycle and has two water molecules in axial sites. The complex crystallises in space group C_2/c with a= 13.739(3), b= 19.262(4), c= 12.860(4)Å, β= 121.55(3)°, and Z= 4. The structure was solved by a combination of Patterson and Fourier-difference techniques and refined to R= 0.089 for 2 153 diffractometer data.