Synthesis of SnI4
Direct reaction of tin metal with iodine in methylene chloride yields SnI4 as the principal product, with formation of SnI2 as a side reaction.
Sn + 2I2 + SnI4
Sn + I2 + SnI2
SnI4 is a red-orange solid; SnI2 is a yellow-red solid.
Color due to polarizability of I–, probably involving charge transfer (I+Sn).