与阳离子作用弱的阴离子被称为非配位阴离子，虽然更准确的术语是弱配位阴离子。非配位阴离子在研究亲电试剂的活性时很有用。它们通常是配位数不饱和的金属配合物中阳离子的平衡离子（电荷相反使整体显电中性）。这些特殊的离子是均相烯烃聚合催化剂中必需的成分，其中活性催化中心配位数不饱和，是过渡金属配合物阳离子。例如，它们被用于平衡14个价电子的阳离子[(C₅H₅)₂ZrR]（R = 甲基或增长的聚乙烯长链）。由非配位阴离子衍生出的配合物已被用于催化氢化、硅氢加成反应（hydrosilylation）、低聚化（oligomerization）以及烯烃的活性聚合。非配位阴离子的普遍使用有助于增进对含抓氢键配合物的了解，其中碳氢化合物和氢是配体。非配位阴离子是许多超强酸的重要成分，因为它们通常是布朗斯特酸和路易斯酸的混合物。

Anions that interact weakly with cations are termed non-coordinating anions, although a more accurate term is 'weakly coordinating anion'. Non-coordinating anions are useful in studying the reactivity of electrophilic cations. They are commonly found as counterions for cationic metal complexes with an unsaturated coordination sphere. These special anions are essential components of homogeneous olefin polymerisation catalysts, where the active catalyst is a coordinatively unsaturated, cationic transition metal complex. For example, they are employed as counterions for the 14 valence electron cations [(C₅H₅)₂ZrR] (R = methyl or a growing polyethylene chain). Complexes derived from noncoordinating anions have been used to catalyze hydrogenation, hydrosilylation, oligomerization, and the living polymerization of olefins. The popularization of non-coordinating anions has contributed to increased understanding of agostic complexes wherein hydrocarbons and hydrogen serve as ligands. Noncoordinating anions are important components of many superacids, which result from the combination of Bronsted acids and Lewis acids.