Stannenes, Distannenes, and Stannynes

Yoshiyuki Mizuhata and Norihiro Tokitoh Institute for Chemical Research, Kyoto University, Japan 

The second-row elements of the Periodic Table, such as boron, carbon, nitrogen, and oxygen are able to form multiple p r—p r bonds, resulting in the development of a wide variety of organic chemistry. 

Much attention has been focused on the chemistry of heavier congeners of alkenes, i.e., dimetallenes ( E=E E = Si, Ge, Sn, Pb), and a number of reports have appeared on their syntheses, structures, and properties Experimental and theoretical studies revealed that their structures and properties are apparently different from olefins ( C=C ). The dominant difference is their trans-bent structures 

In this section, the characteristics of the previously reported distannenes, classified into two types (i) typical examples bearing two three-coordinated Sn atoms, and (ii) tristanaallene bearing formal sp-hybridized Sn atoms, are discussed in detail. 

As mentioned above, the chemistry of distannenes, Sn=Sn , the tin analogs of ethylene, has the longest history among all heavy alkene analogs of the type E=E (E, E are heavier group 14 elements). The first stable compound with an Sn=Sn double bond, 1, was reported by Lappert et al. in 1973. Since then, distannenes 6-17 have been synthesized and characterized, and some of their parameters 

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