Cage Compounds of Heterotrimetallic Mixed Phosphanediide/Silanolate Aggregates with an Alkaline Earth Metal-Centered Phosphorus Octahedron

The lithiation of potassium triisopropylsilylphosphanide yields the corresponding phosphanediide. The subsequent
metathesis reaction with SrI2 and BaI2 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
P3 faces of the octahedron are capped by the K atoms, and the P−P edges of two opposite P3 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.