Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
J Am Soc Mass Spectrom. 2013 Apr;24(4):563-72. doi: 10.1007/s13361-012-0567-8. Epub 2013 Mar 20.
A negatively charged biradical intermediate was successfully generated in the gas phase via cyclization of the deprotonated bicyclo[8.3.0]trideca-12-ene-2,7-diyn-1-one precursor. The inherent negative charge of this biradical allows its characterization via collision-activated dissociation and reactions with a variety of neutral substrates in an FT-ICR mass spectrometer. Although the biradical is unreactive toward reagents that usually react rapidly with positively charged biradicals, such as dimethyl disulfide, it reacts with the halogen-containing substrates carbon tetrachloride, carbon tetrabromide, and bromotrichloromethane via bromine or chlorine atom abstraction, which supports its biradical structure. The results presented in this study indicate that cyclizations commonly used in solution to form biradical intermediates from enediyne compounds may also occur in the gas phase.
通过脱质子的双环[8.3.0]十三碳-12-烯-2,7-二炔-1-酮前体的环化，成功地在气相中生成带负电荷的双自由基中间体。该双自由基的固有负电荷使其能够通过碰撞激活解离（CAD）以及与 FT-ICR 质谱仪中的各种中性底物进行反应来进行表征。尽管该双自由基对通常与正电荷双自由基快速反应的试剂（如二甲基二硫）没有反应性，但它会通过溴或氯原子的提取与含卤素的底物四氯化碳、四溴化碳和三氯溴甲烷发生反应，这支持了其双自由基结构。本研究的结果表明，在溶液中通常用于从烯二炔化合物形成双自由基中间体的环化反应也可能在气相中发生。
