Complexation of lanthanides by linear polyethers in propylene carbonate: a ‘crown-like’ behaviour

Abstract

The stability of lanthanide complexes with tetraglyme (2,5,8,11,14-pentaoxapentadecane) in anhydrous propylene carbonate have been determined by a competitive potentiometric method using lead as an auxiliary ion. The stability sequence exhibited by the linear polyether is very similar to sequences previously reported for 15-membered crown ethers. Furthermore, tetraglyme displays a higher affinity for the divalent Sm^II and Yb^II ions than for the corresponding trivalent ions. Longchain linear polyethers thus exhibit the co-ordination properties of the corresponding crown ligands although the macrocyclic effect of the former is less pronounced. Smaller glymes do not stabilize the +2 oxidation state of the lanthanides.