Can N-heterocyclic germylenes behave as Lewis acids - Is there another side to Meller germylenes?

Abstract

N-Heterocyclic germylenes are known to exist in two structurally different forms, the planar Meller germylenes and the monoimino germylenes that feature an envelope structure. This essay reviews recent reports dealing with radical and cationic Meller type germylenes featuring the monoimino germylene structure, discusses their transformations and relationships, and asks the question whether indeed N-heterocyclic germylenes can be turned into Lewis acids. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2008.