AbstractX‐ray crystal structure determinations of tetramesityldisilene (1) at 295 K, where it is bright orange, and at 173 K, where it is pale yellow, were experimentally equivalent. The thermochromism of1, therefore, is not due to changes in conformation; a vibrational origin is considered. The crystal structure of unsolvated1differs substantially from that of the toluene solvate (1·C7H8) because of different crystal packing of the two forms. These two solid‐state structures are compared with those of four other disil