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)]center dot H2O

Reactions of lanthanide chlorides LnCl(3) 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 t ypes. 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)]. nH(2)O (Ln=La-Gd, n=1; Tb-Lu; n=0) obtained by c ontrolled 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 a ngle sum calculations have been used to rationalise the morphologies of the new complexes.