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，其反应性涉及两个关键步骤：1。通过化学键A-B断裂形成自由基，得到两种高活性自由基物质A（点）和B（点）。这一步骤自发地或通过以热或光的形式施加能量而发生; 2.反应终止，这涉及在两个相似或不相似的基团A（点）+ B（点）之间形成键，得到A-B。大多数这些自由基反应涉及瞬态物种。相比之下，有一些已知的自由基足够稳定，可以放在架子上的瓶子里。不幸的是，由于它们的稳定性，这些物种中的许多物种的反应性不足以参与许多化学转化。然而，有少数化合物在固态下含有弱键或应变键，其在溶液中通过元素-元素键的断裂而部分或完全解离。 这些形成持久的自由基-即具有非常长的寿命但不能“装瓶”的自由基。

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".