The crystal structures of rare-earth diaryl- or dialkylphosphate derivatives are poorly explored. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]chloridotetrakis(methanol-κO)neodymium methanol disolvate, [Nd(C24H34O4P)Cl(CH4O)4]·2CH3OH, (1), and of the lutetium, [Lu(C24H34O4P)Cl(CH4O)4]·2CH3OH, (2), and yttrium, [Y(C24H34O4P)Cl(CH4O)4]·2CH3OH, (3), analogues have been obtained by reactions between lithium bis(2,6-diisopropylphenyl)phosphate and LnCl3(H2O)6 (in a 2:1 ratio) in methanol. Compounds (1)–(3) crystallize in the C2/c space group. Their crystal structures are isomorphous. The molecule possesses C
2 symmetry with a twofold crystallographic axis passing through the Ln and Cl atoms. The bis(2,6-diisopropylphenyl)phosphate ligands all display a κ1
O-monodentate coordination mode. The coordination polyhedron for the metal atom [coordination number (CN) = 7] is a distorted pentagonal bipyramid. Each [Ln{O2P(O-2,6-iPr2C6H3)2}2Cl(CH3OH)4] molecular unit exhibits two intramolecular O—H...O hydrogen bonds, forming six-membered rings, and two intramolecular O—H...Cl interactions, forming four-membered rings. Intermolecular O—H...O hydrogen bonds connect each unit via four noncoordinating methanol molecules with four other units, forming a two-dimensional hydrogen-bond network. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]tetrakis(methanol-κO)(nitrato-κ2
O,O′)neodymium methanol disolvate, [Nd(C24H34O4P)(NO3)(CH4O)4]·2CH3OH, (4), have been obtained in an analogous manner from NdCl3(H2O)6. Compound (4) also crystalizes in the C2/c space group. Its crystal structure is similar to those of (1)–(3). The κ2
O,O′-bidentate nitrate anion is disordered over a twofold axis, being located nearly on it. Half of the molecule is crystallographically unique (CNNd = 8). Unlike (1)–(3), complex (4) exhibits disorder of all three methanol molecules, one isopropyl group of the phosphate ligand and the NO3
− ligand. The structure of (4) displays intra- and intermolecular O—H...O hydrogen bonds similar to those in (1)–(3). Compounds (1)–(4) represent the first reported mononuclear bis[bis(diaryl/dialkyl)phosphate] rare-earth complexes.