Tetrakis distannene

The synthesis of doubly bonded tin compounds by the coupling of stannylenes, however useful, is limited by the need for a stable stannylene and often a second divalent species (for example, a carbene or isonitrile). The simplest example of this reaction is the formation of tetrakis[bis(tri-methylsilyl)methyl]distannene from two molecules of the corresponding stannylene,83 with which it is in equilibrium in solution as evidenced by NMR spectroscopy.91... 

Whereas several reports of doubly bonded tin compounds being sensitive to decomposition in air are to be found in the literature, there is only one instance of a controlled oxidation. Tetrakis[bis(trimethylsilyl)methyl]-distannene was treated with Me3NO to give the corresponding cyclo-1,3-distannoxane."2... 

Similar reactions were performed earlier photochemically from 76, which can be converted into tetrakis(2,4,6-triisopropylphenyl)distannene. 

Tetrakis(triisopropylphenyl)distannene (21-33) is obtained as an intense red solid by the photolysis or thermolysis of hexakis(triisopropylphenyl)tristannane, by way of the intermediate stannylene which can be trapped with 1,3-dienes or 1,2-diones (see Section 21.1.2) the photolytic conversion is quantitative at -78 °C. In solution at 0 °C, the stannylene slowly reverts back to the the cyclotristannane. The X-ray crystal structure has not yet been determined, but the molecule is believed to be twisted with little pyra-midalisation.68 The distannene reacts with phenylacetylene to give the distannacyclobu-tene, with rSnSn 284.0(1) pm. The distannenes 21-35 and 21-36 are formed in the disproportionation reaction shown in equation 21-10. 

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