Issue Date: July 13, 2009
Frustrated Couple Settles For Gases
A good love story is hard to come by in chemistry, so when one does come along, it's worth noting. That's the case for the Lewis acid-base pair B(C6F5)3 and P[C(CH3)3]3. The electron-deficient boron would dearly like to accept phosphorus' lone pair of electrons, and phosphorus would freely give the electrons to boron, if the bulky perfluorophenyl and tert-butyl groups weren't standing in the way. Some good has already come from this forbidden affair: The so-called frustrated Lewis pair can serve as the basis of a metal-free catalyst. In a new twist to the plot, Douglas W. Stephan of the University of Toronto and coworkers report that exposing a solution of B(C6F5)3 and P[C(CH3)3]3 to N2O leads to insertion of the gas between the phosphorus and boron. Phosphorus forgets about boron and donates its lone pair to a nitrogen atom, and the jilted boron takes an electron pair from oxygen (J. Am. Chem. Soc., DOI: 10.1021/ja904377v). Separately, Stephan's group teamed up with Gerhard Erker, Stefan Grimme, and coworkers of the University of Münster, in Germany, to use CO2 as the third party (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200901636). The reversible trapping of N2O and CO2 could provide a means of capturing the greenhouse gases for storage or for activating the molecules for chemical reactions.
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