Tin Alkyne Analog's On-Off Cycloaddition | September 28, 2009 Issue - Vol. 87 Issue 39 | Chemical & Engineering News
Volume 87 Issue 39 | p. 58 | Concentrates
Issue Date: September 28, 2009

Tin Alkyne Analog's On-Off Cycloaddition

A tin analog of acetylene, a compound with a rare Sn≡Sn bond, reversibly adds ethylene across the triple bond under ambient conditions
Department: Science & Technology
Keywords: cycloaddition, multiple bonding
Distannyne adds two ethylene molecules across its Sn≡Sn bond, forming this adduct; tin is red, ethylene groups are black and blue, and the carbon framework of tin's bulky phenyl substituents is gray.
Credit: Yang Peng
8739scon_fig-2_opt
 
Distannyne adds two ethylene molecules across its Sn≡Sn bond, forming this adduct; tin is red, ethylene groups are black and blue, and the carbon framework of tin's bulky phenyl substituents is gray.
Credit: Yang Peng

A tin analog of acetylene, a rare compound with a Sn≡Sn bond, is proving to have unusual reactivity: It reversibly adds two ethylene molecules across the triple bond under ambient conditions, a reaction normally forbidden to its carbon analog, report Yang Peng, Philip P. Power, and coworkers of the University of California, Davis (Science 2009, 325, 1668). Cycloaddition reactions involving alkenes or alkynes are classic transformations in organic synthesis, leading to stable products. These reactions are normally "symmetry forbidden," meaning that under standard conditions the molecular orbital overlap is insufficient for bonding to occur. This barrier can be overcome by boosting the energy of the system with heat or light. In contrast, alkene and alkyne analogs of silicon, germanium, tin, and lead can undergo cycloadditions under mild conditions. But until now, even those reactions were irreversible. The UC Davis team showed that once ethylene adds to the triple bond of the distannyne RSn≡SnR, where R is a bulky phenyl group, the ethylene molecules of the isolable adduct that forms can pop off with a gentle change in temperature or pressure.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

Leave A Comment

*Required to comment