| SYNTHESIS |
First homocyclic lead compound A he proliferation in recent years of multiply bonded and homocyclic compounds of the heavier group 14 elements has been driven by the interest in studying the isostructural relationships of these compounds with their carbon analogs. In the latest development, chemistry professor Manfred Weidenbruch of the University of Oldenburg, in Germany, and coworkers have synthesized the first lead compound with a homocyclic ring system [J. Am. Chem. Soc., 125, 10172 (2003)]. The cyclotriplumbane (shown, R = triethylphenyl) was prepared by reacting triethylphenylmagnesium bromide with lead dibromide. This reaction has been carried out by Weidenbruch's group before using the same or bulkier phenyl substituents, which led to monomeric plumbylenes (PbR2) and diplumbenes (R2Pb5PbR2), the latter containing the first known Pb5Pb bond. In the new work, dioxane was added to suppress formation of MgBr2-bridged plumbylene molecules, which led to formation of the cyclotriplumbane. The X-ray structure reveals longer than expected Pb2Pb bonds and shows that the phenyl groups are 37° out of their ideal positions, suggesting that the lead bonds are not classic single bonds but instead are weak interactions between three singlet plumbylene molecules. |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |