The Element Tin Does What Carbon Will Not

In new experiments, scientists have found tin atoms that have bounded to ethylene, a small molecule consisting of two carbons and four hydrogen atoms. Remember that tin (element 50) is the fourth element in the carbon group; thus it should behave similar chemically to carbon. However, carbon does not undergo the same reaction with ethylene that tin does. In the 1960's chemists Robert Woodward and Roald Hoffmann illustrated that certain reactions involving carbon-containing molecules are more likely than others. Based on the symmetry of orbitals these reactions proceed in a predictable manner. Philip Power of the University of California, Davis and colleagues have demonstrated a reaction with tin that is forbidden by the Woodward-Hoffmann rules for carbon. When hydrocarbon groups were added to tin in solution, a triple bond formed which connected two tin atoms with the hydrocarbons. Then ethylene was dissolved in the solution and the tin atoms "loosened" their triple bond and picked up the ethylene molecules. If tin followed the carbon rules, the triple bond would not have broken to form rings with ethylene. This reaction is significant because it opens up further investigation of carbon's metallic and nonmetallic neighbors and their various properties. Organic chemist Lawrence Sita of the University of Maryland in College Park stated, "This could be a launching point for a number of experiments."

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Posted by Samir Gupta