A state during a reaction that the reactants may pass through - a high energy state that will not be isolated. Compare with intermediate.
On an energy diagram, the maximas (peaks) represent transitions states. A transition state represents the highest energy arrangement of atoms between two more stable forms.
The initial state of a substrate molecule bound to the active site of an enzyme. The transition state is followed by the formation of more stable intermediates prior to product formation.
Structure that forms transiently in the course of a chemical reaction and has the highest free energy of any reaction intermediate; a rate-limiting step in the reaction.
At the saddle point of a col linking two potential wells, the direction of maximum negative curvature defines the reaction coordinate; the transition state is a hypothetical system of reduced dimensionality, free to move only on a hypersurface perpendicular to the reaction coordinate at its point of maximum energy.
Saddle point on a potential energy surface separating chemical reactants from products.
a stationary point on the potential energy surface, that is, the gradient of the potential energy is equal to zero there in all directions
The activated form of a molecule that has partly undergone a chemical reaction.
transition structure Molecule or group of molecules formed during a reaction. Unstable, containing weak bonds and having high energy. Requires energy of activation to form. Vibrates at imaginary frequencies. See also "activation energy", "imaginary frequency"
the highest energy state (and the molecular configuration that corresponds to it) that exists between reactant and product in a chemical reaction.
the point of highest energy on an energy against reaction coordinate curve. [By definition the transition state is the least stable point (peak) on a reaction path; a reaction path may involve more than one transition states.
The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest energy along this reaction coordinate. At this point, assuming a perfectly irreversible reaction, colliding reactant molecules will always go on to form products.
