Tin complexes spirocyclic—

A redox process also occurs in the reaction of selenium diimides with bis(amino)stannylenes. Eor example, the cyclic stannylene McaSi)//-N Bu)2Su reacts in a 1 1 molar ratio with BuN=Sc=N Bu to give a spirocyclic tin complex, which reacts with a second equivalent of the stannylene to generate a Sn-Sn bond [d(Sn-Sn) = 2.85 A, /( Sn- Sn) = 13,865 Hz)] (Scheme 10.6). ... 

For the spirocyclic tin complexes 113a and 109b, the Sn—S bond lengths are much closer. They are two shorter ones, averaging 2.458 and 2.521 A, and two longer ones, averaging 2.455 and 2.516 A, respectively324. This small difference is indicative of a residual TBP character that was expressed by the ca 94 and 97% displacement toward RP. 

SCHEME 6. Relationship between trigonal bipyramid and rectangular pyramid for pentacoordinated spirocyclic germanium and tin complexes... 

This compound was characterized by X-ray studies. Two Sn—N—P—S rings join at tin to form the spirocycle. In this complex, the two rings are arranged in cA-position as illustrated in Figure 9. 

Anionic spirocyclic pentacoordinate tin species having aromatic rings, namely bis(TDT) complexes 113a324 and 113b336, were prepared in high yields by addition of halide ion to bis(toluene-3,4-dithiolato)tin, Sn(TDT)2, (equation 21). 

As in the spirocyclic five-coordinated germanium complexes discussed above, the geometry about the tin atom in some of the mono- and bi-cyclic stannates, listed in... 

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