Tin-containing rings

Keywords Silicon-Containing Rings / Tin-Containing Rings / Ferrocenophane /... 

One additional aspect of the chemistry of tin should be mentioned. That aspect concerns the preparation of unusual tin compounds that contain rings in which there are Sn-Sn bonds. These interesting compounds include (R2Sn)3, in which there is a three-membered ring and which is prepared by the reaction... 

The anionic binuclear monocyclic tin derivatives, 83a and 83b, containing ring saturation, were isolated from the reaction of MeSnCR or n-BuSnCl3, respectively, with Na2(EDT) in the presence of EbjNCl325 (see below). 

More complex tin-rich rings containing S, Se, and Te are known, as are systems in which heterocycles are linked by a spiro center. In the latter case, three compounds of the same composition, RgSnJXi (X = S, R = Pr and Bu X = Se, R = (Pr), have been synthesized by the routes shown in Eqs. (45) and (46). The compounds are conformationally distinct in the solid state (Fig. 7), but these forms equilibrate in solution (183). 

This section covers heterocyclic rings which contain lone pair-bearing heteroatoms within the ring so disposed as to enable additional coordination to tin, thereby generating a collection of fused, tin-containing heterocycles. These are shown in 76 and 77, bicyclic or diptych structures, and 78, a tricyclic or triptych arrangement. The term stannatrane is also commonly used in discussions of these latter systems. These compounds... 

The thermodynamic product would contain oligomers of s-caprolactone as well, formed in ring-contraction reactions (Scheme 11). Cyclics containing more than one tin atom, formed in statistically less frequent reactions of ring-expan-sion/contraction of tin-containing macrocycles. 

Scheme 11 The ring-contraction reaction of the tin-containing macro-cycies of poiy(s-caproiactone) system ieading to s-caprolactone cyclic oiigomers.

Compounds containing two primary amino groups attached to a benzene ring can be prepared by the reduction of dinitro compounds and of nitroanilines, usually with tin or stannous chloride and hydrochloric acid or with iron and very dilute hydrochloric acid. / ara-diamines may also be obtained by the reduction of aromatic amino-azo compounds (e.g., p-aminodimethylanihne from methyl orange, see Section IV,78). p-Phenylenediamine may also be prepared from p-nitroacetanilide reduction with iron and acid yields p-amino-acetaniUde,.which may be hydrolysed to the diamine. 

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