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In chemistry, a reaction coordinate [1] is an abstract one-dimensional coordinate chosen to represent progress along a reaction pathway. Where possible it is usually a geometric parameter that changes during the conversion of one or more molecular entities, such as bond length or bond angle. For example, in the homolytic dissociation of ...
Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram. In all three of these reactions the first step is the slow step because the activation energy from the reactants to the transition state is the highest.
[1] The PES concept finds application in fields such as physics, chemistry and biochemistry, especially in the theoretical sub-branches of these subjects. It can be used to theoretically explore properties of structures composed of atoms, for example, finding the minimum energy shape of a molecule or computing the rates of a chemical reaction.
By modeling reactions as Langevin motion along a one dimensional reaction coordinate, Hendrik Kramers was able to derive a relationship between the shape of the potential energy surface along the reaction coordinate and the transition rates of the system. The formulation relies on approximating the potential energy landscape as a series of ...
Consider the average number of particles with particle properties denoted by a particle state vector (x,r) (where x corresponds to particle properties like size, density, etc. also known as internal coordinates and, r corresponds to spatial position or external coordinates) dispersed in a continuous phase defined by a phase vector Y(r,t) (which again is a function of all such vectors which ...
Chiral ligands work by asymmetric induction somewhere along the reaction coordinate. The image to the right illustrates how a chiral ligand may induce an enantioselective reaction. The ligand (in green) has C 2 symmetry with its nitrogen, oxygen or phosphorus atoms hugging a central metal atom (in red). In this particular ligand the right side ...
In this type of plot (Figure 1), each axis represents a unique reaction coordinate, the corners represent local minima along the potential surface such as reactants, products or intermediates and the energy axis projects vertically out of the page. Changing a single reaction parameter can change the height of one or more of the corners of the plot.
Ideal Conical Intersection. In quantum chemistry, a conical intersection of two or more potential energy surfaces is the set of molecular geometry points where the potential energy surfaces are degenerate (intersect) and the non-adiabatic couplings between these states are non-vanishing.