Complexes of the lanthanide metals (La–Nd, Sm–Lu) with hypophosphite and phosphite ligands: crystal structures of [Ce(H2PO2)3(H2O)], [Dy(H2PO2)3] and [Pr(H2PO2)(HPO3)(H2O)]·H2O

Abstract

Reactions of lanthanide chlorides LnCl₃ with NaH₂PO₂ in aqueous solution afforded a series of complexes [Ln(H₂PO₂)₃(H₂O)_n] (Ln = La–Tb, n = 1; Ce–Nd, Dy–Lu; n = 0) with members falling into at least four separate structural types. The crystal structures of members of two of these types, [Ce(H₂PO₂)₃(H₂O)] and [Dy(H₂PO₂)₃], have been determined for the first time, along with that of [Pr(H₂PO₂)(HPO₃)(H₂O)]·H₂O, one of a new series of complexes [Ln(H₂PO₂)(HPO₃)(H₂O)_n]·nH₂O (Ln = La–Gd, n = 1; Tb–Lu; n = 0) obtained by controlled oxidation of [Ln(H₂PO₂)₃(H₂O)_n]. The hydrated members of this series are notable due to their incorporation of chiral channels inhabited by water molecules, and to their ability reversibly to dehydrate. Steric angle sum calculations have been used to rationalise the morphologies of the new complexes.