C&EN Classifieds
Home | This Week's Contents  |  C&EN ClassifiedsSearch C&EN Online

Millennium Special Report
C&EN 75th Anniversary Issue
Related Person
Hideo Tomioka
E-mail this article to a friend
Print this article
E-mail the editor
 Table of Contents
 C&EN Classifieds
 News of the Week
 Cover Story
 Editor's Page
 Government & Policy
  Government & Policy
 ACS News
 Digital Briefs
 ACS Comments
 Career & Employment
 Special Reports
 New Products
 What's That Stuff?
 Pharmaceutical Century

 Hot Articles
 Safety  Letters

 Back Issues

 How to Subscribe
 Subscription Changes
 About C&EN
 Copyright Permission
 E-mail webmaster
August 13, 2001
Volume 79, Number 33
CENEAR 79 33 p. 11
ISSN 0009-2347
[Previous Story] [Next Story]

Serendipitous discovery may lead to organic ferromagnetic materials


A carbene derivative in the triplet state that is significantly more stable than previously observed triplet carbenes has been serendipitously discovered by chemists in Japan.

Chemistry professor Hideo Tomioka, graduate student Eri Iwamoto, and coworkers at Mie University, Tsu, generated triplet bis(9-anthryl)carbene by photolysis of a precursor diazomethane. The half-life of the carbene is 19 minutes in solution at room temperature, they report [Nature, 412, 626 (2001)].

Carbenes in the electronic triplet state have two nonbonding electrons that occupy different orbitals. Unlike their sister singlet carbenes, which have two nonbonding electrons paired in the same orbital, triplet carbenes are organic radicals. And because their two unpaired electrons have parallel spins, triplet carbenes are potentially useful as building blocks for organic ferromagnetic materials.

Triplet carbenes are notoriously transient and highly reactive species, however. The one prepared by Tomioka's team is stabilized by delocalization of the unpaired electrons onto the anthryl substituents of the carbene.

"We have generated the longest-lived triplet carbene," Tomioka tells C&EN. "The previous most stable one, which we reported in 1999, has a half-life of about nine minutes."

The latest discovery was made while the group was preparing a series of carbene precursor diazo compounds with anthryl groups as substituents.

"We asked Iwamoto, a student who had just joined our group, to prepare di(9-anthryl)diazomethane," Tomioka says. "She prepared it in about two months. Much to our surprise, the carbene generated from the diazo compound was fairly stable."

[Previous Story] [Next Story]


Chemical & Engineering News
Copyright © 2001 American Chemical Society

C&EN Classifieds
Home | Table of Contents | News of the Week | Cover Story
Business | Government & Policy | Science/Technology
Chemical & Engineering News
Copyright © 2001 American Chemical Society - All Right Reserved
1155 16th Street NW • Washington DC 20036 • (202) 872-4600 • (800) 227-5558

CASChemPortChemCenterPubs Page