The reaction of diethylmagnesium with diphenylphosphane yields [(THF)Mg(Et)PPh2](infinity) (1; THF = tetrahydrofuran) with bridging PPh2 ligands and average Mg-P bond lengths of 262.2 pm. The metalation reaction of MgEt2 with HPPh2 and H2PPh with a 1:2 stoichiometry gives [(THF)(4)Mg(PPh2)(2)] (2) and [(THF)(6)Mg-4(P(H)Ph)(8)] (3), respectively. Tetranuclear 3 contains three chemically different phenylphosphanide groups with characteristic P-H stretching frequencies at 2261, 2286, and 2310 cm(-1). The metathesis reaction of potassium phenylphosphanide with Call yields oligomeric (THF)(3)Ca[P(H)Ph](2) (4). A similar reaction with Srl(2) and Bal(2) gives polymeric [(THF)(2)Sr(P(H)Ph)(2)](infinity) (5) and [(THF)Ba{P(H)Ph)(2)](infinity) (6), respectively, showing one stretching frequency at 2285 cm-1. These compounds crystallize polymeric with bridging phenylphosphanide substituents. The addition of Et2O to a mixture of KPPh2 and Mg(PPh2)(2) in THF initiates the crystallization of (Et2O)K[(THF)Mg(PPh2)(3)] (7) with a strand structure and (Et2O)(x)(THF)(y)K-2[Mg(PPh2)(4)] (8) with a layer structure depending on the stoichiometry. The crystals of 8 easily lose THF and Et2O and, therefore, the content of these ethers varies. Recrystallization of 8 from hot 1,4-dioxane (diox) yields (diox)(2)K-2[Mg(PPh2)(4)] (9) with a layer structure comparable to that of 8. The central structural units are eight-membered K2Mg2P4 rings that are interconnected by P-K-P bridges. In a THF solution, the magnesiates 7-9 dissociate into the homometallic derivatives KPPh2 and Mg(PPh2)(2), as can be seen from NMR experiments.