Preparation, properties and X-ray structure of a cyclic compartmental Schiff base and related complexes containing d- or f-metal ions

A new compartmental ligand (H2LA) containing an N2O2 Schiff base and an O2O4 'crown like' coordination site has been prepared by reaction of 3,3'-(3,6-dioxaoctane-1,8-diyldioxy)bis(2-hydroxybenzaldehyde) with ethylenediamine and the [1 + 1] cyclic nature was confirmed by its X-ray single crystal structural determination. When reacted with d- or f-metal ions, H2LA forms mononuclear complexes where the metal ion coordinates respectively the N2O2 or the O2O4 chamber. The X-ray structure of [La(H2LA)(H2O)(4)]Cl-3 shows the ten-coordination about the metal ion is reached by the six oxygen atoms of the compartmental ligand and by the oxygen atoms of four water molecules; the chloride atoms are ionic.