Agostic interactions, defined as 3-center–2-electron M–H–C bonds, significantly influence the structures and reactivity of organotransition metal compounds. These interactions, first recognized in the 1970s, involve the C–H bond donating electron density to a metal center, often leading to unique structural and spectroscopic characteristics. The term "agostic" was coined to describe this specific type of interaction, distinguishing it from other 3-center–2-electron bonds. Agostic interactions are common in organometallic chemistry and play a crucial role in catalytic reactions, influencing reaction mechanisms and product selectivity. The study of agostic interactions has evolved from early structural observations to a well-established area of research. Key developments include the structural characterization of the first β-agostic metal-alkyl compound, the identification of dynamic equilibria in agostic complexes, and the recognition of agostic interactions in various transition metal compounds. Agostic interactions are distinguished from anagostic interactions, which involve different bonding characteristics and are often associated with longer M–H distances and larger bond angles. Agostic interactions are particularly significant in reaction intermediates and transition states, influencing the stereochemistry and selectivity of catalytic processes. For example, in olefin polymerization, agostic interactions control the stereochemistry of the resulting polymers. The role of agostic interactions in polymerization mechanisms, such as in the insertion of olefins into transition metal bonds, has been extensively studied. These interactions are also important in the isomerization and dimerization of olefins, where they influence the spatial arrangement of molecules. The importance of agostic interactions is further highlighted by their influence on the stability and reactivity of metal complexes. Agostic interactions can stabilize reaction intermediates and influence the formation of transition states, which is critical in catalytic processes. The distinction between agostic and anagostic interactions is essential for understanding the behavior of metal complexes and their reactivity. Despite their significance, the nature of these interactions can sometimes be ambiguous, requiring careful analysis to determine the correct classification. Overall, agostic interactions are a fundamental aspect of organometallic chemistry, influencing the structures, reactivities, and catalytic properties of transition metal compounds. Their study continues to provide insights into the mechanisms of chemical reactions and the design of efficient catalysts.Agostic interactions, defined as 3-center–2-electron M–H–C bonds, significantly influence the structures and reactivity of organotransition metal compounds. These interactions, first recognized in the 1970s, involve the C–H bond donating electron density to a metal center, often leading to unique structural and spectroscopic characteristics. The term "agostic" was coined to describe this specific type of interaction, distinguishing it from other 3-center–2-electron bonds. Agostic interactions are common in organometallic chemistry and play a crucial role in catalytic reactions, influencing reaction mechanisms and product selectivity. The study of agostic interactions has evolved from early structural observations to a well-established area of research. Key developments include the structural characterization of the first β-agostic metal-alkyl compound, the identification of dynamic equilibria in agostic complexes, and the recognition of agostic interactions in various transition metal compounds. Agostic interactions are distinguished from anagostic interactions, which involve different bonding characteristics and are often associated with longer M–H distances and larger bond angles. Agostic interactions are particularly significant in reaction intermediates and transition states, influencing the stereochemistry and selectivity of catalytic processes. For example, in olefin polymerization, agostic interactions control the stereochemistry of the resulting polymers. The role of agostic interactions in polymerization mechanisms, such as in the insertion of olefins into transition metal bonds, has been extensively studied. These interactions are also important in the isomerization and dimerization of olefins, where they influence the spatial arrangement of molecules. The importance of agostic interactions is further highlighted by their influence on the stability and reactivity of metal complexes. Agostic interactions can stabilize reaction intermediates and influence the formation of transition states, which is critical in catalytic processes. The distinction between agostic and anagostic interactions is essential for understanding the behavior of metal complexes and their reactivity. Despite their significance, the nature of these interactions can sometimes be ambiguous, requiring careful analysis to determine the correct classification. Overall, agostic interactions are a fundamental aspect of organometallic chemistry, influencing the structures, reactivities, and catalytic properties of transition metal compounds. Their study continues to provide insights into the mechanisms of chemical reactions and the design of efficient catalysts.