Asymmetric Choreography in Pairs of Orthogonal Rotors.

An asymmetric mechanism for correlated motion occurring in noninteracting pairs of adjacent orthogonal 1,4-bis(carboxyethynyl)bicyclo[1.1.1]pentane (BCP) rotators 1 in the solid state is unraveled and shown to play an important role in understanding the dynamics in the crystalline rotor, Bu4 N+ [ 1 - ]·H2 O. Single crystal X-ray diffraction and calculation of rotor-rotor interaction energies combined with variable-temperature, variable-field 1 H spin-lattice relaxation experiments led to the identification and microscopic rationalization of two distinct relaxation processes.