A comprehensive review of structurally characterized rare-earth metal complexes containing anionic phosphorus ligands is presented. Since rare-earth elements form hard ions and phosphorus is considered as a soft ligand, the rare-earth metal phosphorus coordination is regarded as a less favorite combination. Three classes of phosphorus ligands, (1) the monoanionic organophosphide ligands (PR2−) bearing one negative charge on the phosphorus atom; (2) the dianionic phosphinidene (PR2−) and P3− ligands; and (3) the pure inorganic polyphosphide ligands (Pnx−), are included here. Particular attention has been paid to the synthesis, structure, and reactivity of the rare-earth metal phosphides.
