Tin(II) halides react with mercury compounds such as RR′Hg [R =π-C5H5Fe(CO)2, π-C5H5Mo(CO)3, π-C5H5W(CO)3, Co(CO)4, Co(CO)3(Bun3P); R = R or Cl] to yield compounds with tin–metal bond(s) such as RR′SnX2 or RSnX3. The nature of the reaction is discussed.