Initial organotin chemistry

In 1849, attempts to isolate free alkyl groups led to discovery of an organostannane, (C2H5)2SnI2, which was analyzed in 1852. Coevally, aims at extension of trialkylstibine and trialkyl bismuth chemistry yielded [(C2H5)2Sn]n, finally consisting rather of (cyclic) oligostannanes than polystannanes; the latter might have been degraded to the former though. Further, those reports described conversion of (C2H5)2SnI2 or [(C2H5)2Sn]n to (C2H5)2SnO, in fact a polymer, [(C2H5)2SnO]n. These three substances were employed as starting materials for exploration of new alkylstannanes, and moreover some of the compounds thus obtained were used for synthesis of other organostannanes. Thus, e.g., dialkylstannanes (C2H5)2SnX2 (X = Br, Cl, nitrate, formate, acetate) and a number of corresponding methyl derivatives were prepared, as well as (C2H5)2SnSO4, (CH3)2SnSO4, (C2H5)2Sn(C2O4) and tetraalkylstannanes. Dinuclear tin compounds were also addressed, in particular (C2H5)3Sn–Sn(C2H5)3, (C2H5)2ISn–Sn(C2H5)2I, and (C2H5)3SnOSn(C2H5)3. The latter arose as a reversibly formed dehydration product of (C2H5)3SnOH. This hydroxide and (CH3)3SnOH served for the synthesis of trialkylstannanes R3SnX (R = ethyl: X = Br, Cl; R = ethyl or methyl: X = formate, acetate, butyrate), [(C2H5)3Sn]2SO4, [(CH3)3Sn]2SO4 and [(C2H5)3Sn]2(C2O4). Among the synthesis routes substitution and addition reactions were applied, and even the so-called Kocheshkov redistribution reaction (Kocheshkov comproportionation) was already described, namely by Buckton who thus obtained (C2H5)3SnCl. Hence, already by 1860 a diversity of organotin compounds and related reactions was established, and the base for methodical exploration of organotin compounds was laid.