Phosphanides of calcium and their oxidation products

► Phosphanes are poor ligands for the rather hard calcium cations whereas calcium complexes with phosphane oxide ligands are feasible. ► Phosphanides and their oxidation products (phosphinites and phosphinates, and phosphonates) represent a multifaceted class of ligands in coordination chemistry. ► Phosphanides of calcium represent valuable catalysts for hydrophosphanylation reactions. ► Taking Grimm's hydride displacement law (O/NH/CH2 and O/N−/CH−/C2−) into account, structures and properties of many compounds can be attributed to phosphorus-based acids and anions. ► Phosphorus-based anions with two or three oxygen atoms (phosphinates and phosphonates) always act as bridging ligands between calcium cations.