Trinuclear coinage metal metallacycles are obtained when two-coordinate metals are bonded to C, N or N, N anionic ligands of the proper symmetry to form cycles where metals alternate with bridging ligands. Cyclotrimers often exhibit semiplanar structures and mostly columnar or finite stacking in the solid state by means of metallophilic interactions. They show some peculiar properties with an impact on many different fields such as supramolecular architectures, luminescence, molecular recognition, host-guest chemistry, and acid-base chemistry. The comprehensive evaluation of the data shows that, depending on the nature of the central metal and bridging ligand, there is a fine balance of the energy involved in the inter-trimer bond cleavages and the energy gained from the formation of new intermolecular electrostatic interactions, proceeding occasionally to the chemical extreme of redox processes. In this review, a number of important developments are highlighted and systematically analyzed along with structural and computational data and chemical properties to rationalize and build a unifying leitmotif for this chemistry; the focus is made on the authors’ contributions in these areas.

当二配位金属键合到具有适当对称性的C，N或N，N阴离子配体上形成金属与桥连配体交替的循环时，就会获得三核纽扣金属金属环。亲环分子通常通过亲金属相互作用而表现出半平面结构，并且大多数呈固态的柱状或有限堆积。它们显示出一些独特的特性，这些特性会影响许多不同的领域，例如超分子体系结构，发光，分子识别，主体客体化学和酸碱化学。数据的综合评估表明，根据中心金属和桥联配体的性质，三聚体间键裂解所涉及的能量与新分子间静电相互作用形成所获得的能量之间存在良好的平衡，偶尔进行到氧化还原过程的化学极端反应。在这篇综述中，重点介绍了许多重要的进展，并对其进行了系统的分析，并对其结构和计算数据以及化学性质进行了分析，以合理化和构建该化学的统一主题。重点是作者在这些领域的贡献。