reactanten

Reactanten is a term used in chemistry to describe transient reactive species that appear temporarily during the early stages of a reaction. These species are typically short-lived and highly reactive, existing only for a fraction of a second (or less) before either converting into final products or reverting to starting materials. The concept is used mainly in theoretical discussions and in ultrafast experiments where intermediates cannot be captured directly.

Characteristics include brief lifetimes ranging from femtoseconds to microseconds, high reactivity, and often unconventional bonding arrangements that place fragments from different reactants in a single, coordinated arrangement. They may be neutral or charged and can arise in homogeneous solutions, solid-state environments, or at catalytic interfaces. Common formation routes include photoexcitation, rapid electron transfer, or solvent cage dynamics that stabilize an otherwise fleeting configuration.

Detection and study rely on time-resolved spectroscopic techniques, such as transient absorption or infrared spectroscopy, sometimes combined with matrix isolation. Computational methods, including density functional theory and ab initio calculations, are used to propose plausible structures and reaction coordinates. However, the term is not universally adopted; in many sources such species are described as reactive intermediates or as short-lived transition-state analogs rather than as a distinct class.

Applications of the concept lie in elucidating reaction mechanisms, informing kinetic models, and guiding catalyst or solvent design to steer pathways toward desired products. Related topics include reaction mechanisms, reactive intermediates, and transient species.