Molecules with different resonance structures of similar importance, such as heterocumulenes and mesoionics, are prominent in many applications of chemistry, including ‘click chemistry’, photochemistry, switching and sensing. In coordination chemistry, similar chameleonic/schizophrenic entities are referred to as ambidentate/ambiphilic or cooperative ligands. Examples of these had remained, for a long time, limited to a handful of archetypal compounds that were mere curiosities. In this Review, we describe ambiphilicity — or, rather, ‘charge frustration’ — as a general guiding principle for ligand design and functional group transfer. We first give a historical account of organic zwitterions and discuss their electronic structures and applications. Our discussion then focuses on zwitterionic ligands and their metal complexes, such as those of ylidic and redox-active ligands. Finally, we present new approaches to single-atom transfer using cumulated small molecules and outline emerging areas, such as bond activation and stable donor–acceptor ligand systems for reversible 1e⁻ chemistry or switching.

具有相似重要性的不同共振结构的分子，例如杂积烯和介离子，在许多化学应用中都很突出，包括“点击化学”、光化学、开关和传感。在配位化学中，类似的变色龙/精神分裂症实体被称为双齿/双亲或协同配体。很长一段时间以来，这些例子都仅限于少数仅是好奇心的原型化合物。在这篇综述中，我们将双亲性——或者更确切地说，“电荷受挫”——描述为配体设计和官能团转移的一般指导原则。我们首先介绍有机两性离子的历史，并讨论它们的电子结构和应用。然后我们的讨论集中在两性离子配体及其金属配合物上，例如那些 ylidic 和氧化还原活性配体。最后，我们提出了使用累积小分子进行单原子转移的新方法，并概述了新兴领域，例如键激活和可逆 1e 的稳定供体-受体配体系统⁻化学或开关。