As the ring size of the terminal group increases, the two nitrogen-bonded CH 2 groups are pulled closer towards the oxygen and the α-carbon in the main warhead body. This results in repulsion between the oxygen and a carbon in the terminal group and attraction between the oxygen and a hydrogen in the terminal group, and these interactions strengthen as the ring size of the terminal group increases. An area of non-bonded overlap located at the center of the piperidinyl rings can also be seen.