Stannylenes disproportionation

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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