The lithiation of potassium triisopropylsilylphosphanide yields the corresponding phosphanediide. The subsequent metathesis reaction with Srl(2) and Bal(2) in the presence of hexamethyldisiloxane gives hexalithium hexapotassium strontium hexakis(triisopropylsilylphosphanediide)bis(trimethylsilanolate ) (1) and the corresponding barium derivative (2), respectively. The alkaline earth metal atoms are surrounded octahedrally by the phosphanediide ligands. Six P-3 faces of the octahedron are capped by the K atoms, and the P-P edges of two opposite P-3 faces are bridged by the lithium atoms. The Li cations are also bonded to the Me3SiO substituents giving a coordination number of three for the alkali metals.