Elusive bowtie pinned down.
Down the hall from the makers of the now-famous buckyballs, neighboring chemists have synthesized another long-sought carbonaceous compound and have given it an equally flip moniker. Their bowtie-shaped molecule, officially called spiropentadiene, but nicknamed bowtiediene, consists of five carbon and four hydrogen atoms. The compound had fascinated theoreticians -- and eluded experimentalists -- for decades because of the very strained configuration of its carbon atoms. Its simple structure would pack in so much energy that chemists could not figure out how to make it stay together.But W.E. Billups and Michael M. Haley of Rice University in Houston accepted the challenge. And in the June 19 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, they report producing the molecule.
"It's a classical molecule that will probably find its way into textbooks," William P. Dailey, an organic chemist from the University of Pennsylvania in Philadelphia, told SCIENCE NEWS. "I was very excited to hear about this."
The molecule, which resembles a bowtie with one side bent perpendicular to the other, belongs to a chemical family called the spiroalkenes, whose members possess a single carbon at their cores.
Even though they had never seenit, theoreticians were tantalized by the size and inherent instability of the hypothetical molecule, and had sought to predict its properties. Each end of the bow consists of a doubly bonded pair of carbon atoms; a hydrogen atom hangs off each outer carbon. "It's aesthetically pleasing because of its simplicity and its symmetry," says Dailey. Those double bonds, though separated in space, are close enough to interact and to greatly stress the molecule's structure, adding to its appeal to researchers.
To make bowtiediene, Billups and his co-workers placed an unusual silicon-based compound in a reaction apparatus designed to generate gaseous, high-energy compounds. They collected the product in a tube cooled by liquid nitrogen. When sufficiently chilled, the compound's carbons stayed together allowing them to perform analyses that confirmed its identity. The Rice team next plans to send a student to Germany to collaborate with researchers there in an attempt to find out whether the double bonds interact as theorized.
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| Title Annotation: | synthesis of spiropentadiene, a carbonaceous compound nicknamed bowtiediene because it is shaped like a bowtie |
|---|---|
| Publication: | Science News |
| Date: | Jul 13, 1991 |
| Words: | 347 |
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