On the formation of permethylcyclopolysilanes in the würtz-type reaction of Me2SiCl2: The influence of solvent and complexing agent

Permethylcyclopolysilanes are most often prepared by Würtz-type coupling of Me₂SiCl₂ with Na K alloy in THI: When nonpolar solvents like benzene were used, only linear polysilanes (Me₂Si)_n were produced, but the addition of a catalytic amount of crown ether 18-crown-6 was found to increase significantly the amount of cyclic oligomers. The ratio of (Me₂Si)₆ to (Me₂Si)₅ decreased from 18:1 to 6:1 in the presence of crown ether in a typical synthesis in THF. An explanation based on solvated electron theory has been proposed.