All four tin-carbon bonds of tetra-p-tolyltin can be successively cleaved by iodoacetic acid. Reactions with tetra-m-tolyltin are sluggish and only one tin-carbon bond is cleaved, even in the presence of an excess of the acid. Tetra-o-tolyltin does not react under similar conditions. Stene factors arc thought to be responsible for this difference in reactivity of tetratolyltins. The monocarboxylates were not isolated in case of Ph4Sn (except with CCl3COOH). Tetraphenylgermanium gives only the monocarboxylates Ph3GeOOCR', (R = CH2CI, CH2Br, CH2I), but all the Ph-Pb bonds in tetraphenyllead may be successively cleaved. Tri-p-tolyltin chloride reacts with iodoacetic acid to give a mixed chloro halocarboxylate, (p-MeC6H4)2SnC1(OOCCH2I), but attempts to prepare a mixed carboxylate by reacting (p-MeC6H4)3SnOOCCH2CI with HOOCCH2I failed.