Synthesis and reactivity of molecules containing strained homonuclear element-element bonds

自由基是许多化学转化的关键中间体，它们的反应涉及两个关键步骤：1.通过断裂化学键A-B形成自由基，得到两种高活性的自由基物种A(点)和B(点)。这一步骤自发地发生，或通过以热或光的形式施加能量发生；2.终止反应，这涉及到两个相似或不同的自由基之间形成键，A(点)B(点)以得到A-B。这些自由基反应大多涉及瞬变物种。相比之下，有一些已知的自由基足够稳定，可以放在货架上的瓶子里。不幸的是，由于它们的稳定性，这些物种中的许多没有足够的活性来参与一些化学转化。然而，有少数化合物在固态中含有弱键或张力键，它们在溶液中通过元素-元素键的断裂部分或完全解离。这些形成了持久的自由基--即一种寿命很长，但不能“装瓶”的激进分子。

Radicals are key intermediates in a number of chemical transformations and their reactivity involves two key steps: 1. Radical formation via breaking of a chemical bond, A-B, to give two highly reactive radical species A(dot) and B(dot). This step occurs spontaneously or through the application of energy in the form of heat or light; 2. Termination of the reaction and this involves the formation of a bond between two similar or dissimilar radicals, A(dot) + B(dot) to give A-B. Most of these radical reactions involve transient species. In contrast, there are some known radicals that are stable enough to be placed in a bottle on the shelf. Unfortunately, because of their stability, many of these species are not reactive enough to participate in a number of chemical transformations. However, there are a handful of compounds that contain weak or strained bonds in the solid state that either partially or fully dissociate in solution through breaking of the element-element bond. These form persistent radicals--i.e. a radical that has a very long lifetime, but is not "bottle-able".