Structure and Reactivity of Transient Carbenes

化学结构、动力学和机理B项目支持罗格斯大学的Robert A. Moss教授研究瞬态碳的结构和反应性。这项工作的科学目标是从事反应中间体的机理表征，特别是碳烯和碳离子的化学性质。它的统一主题是结构与高活性，短寿命中间体的反应性的相关性。高活性碳烯Cl-C-CN、F-C-CN、Cl-C-CF3和F-C-CF3的活化参数将被确定。研究结果将对碳烯加成反应的焓熵补偿操作产生影响。将测量[PhCX + Y- = PhCXY-]的平衡常数和热力学参数，其中X，Y = F， Cl和Br。烷基氯烃与芳香族的瞬态配合物将进行光谱和计算表征。探讨络合对碳反应性的调节作用。F-C-OPh包封在与水相容的半羧酸中，其化学性质将被探讨。最后，研究了亲核和两亲碳烯在锂盐作用下的亲性变化。卡贝烯是一种非常不寻常的碳基分子，具有极强的活性，在室温下在溶液中只存在十亿分之一秒。Carbenes可以以不同的几何形状存在，其外层电子的排列也不同，这就导致了不同的反应性。在这个研究项目中，一组详细的快速光谱测量被用来确定这些有趣分子的几何变化和反应性之间的关系。Moss教授是2014年在墨西哥举行的反应中间体和异常分子国际研讨会（ISRIUM）协调委员会主席。

The Chemical Structure, Dynamics, and Mechanisms B Program supports Professor Robert A. Moss of Rutgers University to investigate the structure and reactivity of transient carbenes. The scientific objective of this work is to engage in mechanistic characterization of reactive intermediates, especially the chemistry of carbenes and carbanions. Its unifying theme is the correlation of structure with reactivity for highly reactive, short-lived intermediates. Activation parameters will be determined for carbene-alkene additions of the highly reactive carbenes Cl-C-CN, F-C-CN, Cl-C-CF3, and F-C-CF3. The results will bear upon the operation of enthalpy/entropy compensation in carbene/alkene addition reactions. Equilibrium constants and thermodynamic parameters will be measured for [PhCX + Y- = PhCXY-], where X,Y = F, Cl, and Br. Transient complexes of alkylchlorocarbenes with aromatic partners will be spectroscopically and computationally characterized. Modulation of carbenic reactivity by complexation will be probed. The chemistry of F-C-OPh encapsulated in a water-compatible hemicarcerand will be explored. Finally, the "umpolung" or philicity alteration of nucleophilic and ambiphilic carbenes by reaction with lithium salts will be studied.Carbenes are very unusual carbon-based molecules that are extremely reactive, living only billionths of a second in solution at room temperature. Carbenes can exist in different geometries with different arrangements of their outer electrons and this can lead to different reactivities. In this research project, a detailed set of fast spectroscopic measurements is made to determine the relationship between the geometry changes and the reactivity of these interesting molecules. Professor Moss is the Chair of the Coordinating Committee of the International Symposium on Reactive Intermediates and Unusual Molecules (ISRIUM), meeting in Mexico in 2014.