抓氢键（又称agostic键）是一种烷基、烯基、炔基或芳基中的氢与过渡金属间形成的3c2e键。

• 抓氢键（agostic bond）用C-H⇀M或B-H⇀M表示
  • M表示过渡金属原子，半个箭头⇀表示它用空轨道接受从C-H σ键或B-H σ键上的电子形成的三中心二电子键。
• 注：半箭头⇀，Unicode代码21C0，您的浏览器可能显示为一个方框或问号等。半箭头的形状：→去掉下方的箭头。

Agostic interaction is a term in organometallic chemistry for the interaction of a coordinatively-unsaturated transition metal with a C-H bond, when the two electrons involved in the C-H bond enter the empty d-orbital of a transition metal, resulting in a three-center two-electron bond. Many catalytic transformations, e.g. oxidative addition and reductive elimination, are proposed to proceed via intermediates featuring agostic interactions. Agostic interactions are observed throughout organometallic chemistry in alkyl, alkylidene, and polyenyl ligands.