Trimethylsilylated Allyl Complexes of the Heavy Alkali Metals, M[1,3-(SiMe₃)₂C₃H₃](thf)_n (M = K, Cs)

Reaction of elemental cesium with 1,3-bis(trimethylsilyl)propene produces the corresponding substituted allyl derivative. The complex and its previously prepared potassium counterpart form the THF solvates K[1,3-(SiMe₃)₂C₃H₃](thf)_3/2 and Cs[1,3-(SiMe₃)₂C₃H₃](thf), respectively, which crystallize as coordination polymers in the solid state. In the case of the cesium complex, the packing is polymeric in two dimensions. As was previously found for the potassium complex, the cesium compound is an initiator for methyl methacrylate polymerization.