The discussion of the adsorption structures only shows the thermodynamics of the adsorption. The reaction kinetics resulting from the reaction barriers play an essential role if we want to discuss regioselective adsorption as a prerequisite for ordered layers. Hence, we calculated the stationary points connected to the respective reaction paths leading to 6-4 and 8-4 (Figure ). The observed mechanism follows the asynchronous [2+2] cycloaddition similar to the reaction with Si(001). This means, we have just one reaction barrier, but a non-symmetric approach of the triple bond towards the surface atoms. Notably, the symmetric cycloaddition is well-known to be symmetry-forbidden. For COC on BPN, a barrier results from the formation of the first C-C bond, whereas the ring closure proceeds without further barrier or intermediate. The asymmetric cycloaddition is a result of the symmetry observed in the frontier orbitals. The HOMO of COC is a bonding π-orbital (Figure ) with a nodal plane parallel to the bonding axis (Figure ). The crystal orbitals of BPN however (Figure For the reaction leading to 6-4, a reaction barrier of 89 kJ mol -1 is observed, starting from a dispersion-bound precursor, whereas a barrier of 78 kJ mol -1 is observed for 8-4. The observed difference here is opposed to the trend in thermodynamic stability favoring the kinetics of 8-4 by 11 kJ mol -1 . This difference results only from dispersion interaction, as the precursor of 6-4 is additionally stabilized by 5 kJ mol -1 and the transition state of 8-4 by 6 kJ mol -1 (Figure ).