Unusual motion of the n-methoxypropyl moiety observed in the photochromic crystals of an organorhodium dithionite complex with n-methoxypropyltetramethylcyclopentadienyl ligands.

The crystalline-state photochromism of a new organorhodium dinuclear complex having n-methoxypropyltetramethylcyclopentadienyl (η5-C5Me4n-C3H6OCH3) and photoresponsive dithionite (μ-O2SSO2) ligands was investigated directly by performing single-crystal X-ray diffraction experiments; a reversible conformational change of the n-methoxypropyl moiety was intriguingly observed during the course of a thermal back-reaction.