Solid-state Dynamics of Binuclear N-Heterocyclic Carbene Au(I) Rotor with para-Phenylene Rotator

Molecular dynamics in the crystalline solid state, typically constrained by a densely packed crystal environment, may offer opportunities to control the physical properties of solid-state materials. In this work, a neutral crystalline molecular rotor featuring a para-phenylene rotator encapsulated by N-heterocyclic carbene ligands and connected via a C-Au-C rotational axis is presented. Single-crystal X-ray diffraction studies, along with variable-temperature solid-state 2H NMR spin-echo measurements, confirm the presence of 180° 2-fold rotational dynamics of the para-phenylene moiety in the solid state.