Thermolysis of the heterobimetallic phosphinidene complex {[Sb(PCy)(3)](2)L(i)6 . 6HNMe(2)} (Cy = C6H11) at 303 to 313 kelvin gives Zintl compounds containing (Sb-7)(3-) anions. The complex thus constitutes a stable molecular single-source precursor to Zintl compounds and provides a potential Low-temperature route to photoactive alkali metal antimonates. The new chemical reaction involved, which is driven thermodynamically by the formation of P-P bonds, has implications in the Low-temperature synthesis of other technologically important materials (such as gallium arsenide).