Beyond carbocations: Synthesis, structure and reactivity of heavier Group 14 element cations

Carbocations represent one of the most active organic compounds. Many efforts have been paid in extending the chemistry of carbocations down the group to the heavier elements (Si, Ge, Sn and Pb). It has long been known that elements in a group share very similar properties, such as the coordination geometry and reactivity. The first results on heavier Group 14 element cations that appeared at the end of the past century corroborated this rule. However, a large number of novel heavier Group 14 element cations, many of which displayed very different coordination geometry and frontier orbital configurations compared to classical carbocations, have been synthesized in recent years utilizing specially designed ligands. As a result of the novel structure and frontier orbital configuration, some of the newly reported heavier Group 14 element cations have been used in catalysis, bond activation and small molecule activation. This review focused on the survey of synthesis, structure and reactivity of the recently reported heavier Group 14 element cations. (C) 2016 Elsevier B.V. All rights reserved.