The effect of halides and protic reagents upon the silicon–arsenic and tin–arsenic bonds in Me3SiAsMe2 and Me3SnAsMe2 respectively has been investigated. Halogens and covalent halides have invariably caused fission of both the silicon–arsenic and the tin–arsenic bonds. Protic reagents were, however, somewhat more selective, in that whilst hydrogen sulphide and thiols caused fission of both silicon–arsenic and tin–arsenic bonds, water and ...