Affiliation:
1. Key Laboratory of Cluster Science of Ministry of Education School of Chemistry and Chemical Engineering Beijing Institute of Technology Liangxiang Campus Beijing 102488 China
2. The Smart Materials Research Institute Southern Federal University Sladkova 178/24 Rotov-on-Don 344090 Russian Federation
3. Institute of Physical and Organic Chemistry Southern Federal University Stachka Avenue 194/2 Rotov-on-Don 344090 Russian Federation
Abstract
AbstractA mononuclear valence tautomeric (VT) complex, [Co(pycz)2(Sq)(Cat)] (1‐trans), where pycz = 9‐(pyridin‐4‐yl)‐9H‐carbazole, Sq⋅− = 3,5‐di‐tert‐butyl‐semiquinonato, and Cat2− = 3,5‐di‐tert‐butyl‐catecholato, is synthesized in the trans configuration, which undergoes one‐step valence tautomeric transition above room temperature. Remarkably, 1‐trans can transform into its isomeric structure, [Co(pycz)2(Sq)(Sq)] (1‐cis), at temperature above 350 K in a single‐crystal‐to‐single‐crystal way by in situ molecular twist, and the resulting 1‐cis exhibits a pronounced two‐step VT transition during magnetic measurements that is rare for mononuclear VT complexes. Such drastic solid‐state structural transformation is reported in VT compounds for the first time, which is actuated by a crystal surface's melting‐recrystallization induced phase transition process. DFT calculations offer an underlying mechanism suggesting a concerted bond rotation during the structural transformation. The results demonstrate an unconventional approach that realizes structural transformation of VT complexes and the control of VT performance.
Funder
National Natural Science Foundation of China
Ministry of Science and Higher Education of the Russian Federation