Crystal structures of four rare-earth (La, Nd, Er, Lu) complexes with di(hydroxymethyl)phosphinic acid

The structures of four rare-earth compounds, LaL3 (I), NdL3 (II), ErL3.H2O (III), and LuL3 (IV), where HL is di(hydroxymethyl)phosphinic acid (HOCH2)P O(OH), were studied by X-ray diffraction. The crystals of complexes I and I I are isostructural. The central atom in structures I-IV is bonded to six p hosphinic O(P) atoms of six L ligands. The coordination of the metal atoms in I and II is completed to a distorted dodecahedron (6 O(P) + 2 O(C)) by t wo hydroxyl oxygen atoms of two I, ligands. The coordination polyhedron is a distorted pentagonal bipyramid (6 O(P)+ O(C)) for the Er atom in structur e III and a nearly regular octahedron (6 O(P)) fur the Lu atom in IV. The m etal atom in I-IV is hound to six L ligands Forming a layer structure. In I II, the layers are united by hydrogen bonds involving crystal water molecul es. The L ligands in structures I-IV Function either as bidentate mu (2) br idges (2 O(P); one independent ligand in I and II, two ligands in III, all three ligands in IV) or tridentate mu (3) bridges (2 O(P)+ O(C); two ligand s in I and II, one ligand in III).