The crystal structure of the eight-coordinated erbium(III) complex with the tetradentate ligand N,N′-ethylene-bis(salicylaldimine)

The crystal structure of Er(III)(salen)2(pipH) [salen=N,N′-ethylene-bis(salicylaldimine),pipH= piperidinium] has been determined by X-ray diffraction. The structure of the compound consists of [Er(salen)2]−1 anions and pipH+ cations. In the complex anion the erbium(III) ion is eight-coordinated by the donor atoms of two tetradentate salen ligands, forming a distorted square antiprism with approximate D2 symmetry. The ErO and ErN distances average respectively 2.270 and 2.511 A. This is the first structural determination of a lanthanide element complex with a tetradentate ligand.