 The first indication that the reaction of Si"X"4 and Si yields a higher halide Sin"X"2n+2 (n > 1) was in 1871 for the comproportionation reaction of SiCl4 vapor and Si at white heat to give Si2Cl6.This was discovered by the French chemists (1825 - 191) and (1836–1902).Since that time, it has been shown that gaseous silicon dihalide molecules (Si"X"2) are formed as intermediates in the Si/Si"X"4 reactions.