Structures, Thermal Properties, and Reactivities of Cationic Rh-cod Complexes in Solid State (cod = 1,5-Cyclooctadiene).

Cationic rhodium complexes with 1,5-cyclooctadiene (cod) ligands are important organometallic compounds that are useful as precatalysts; however, their solid-state structures and thermal properties have not been adequately investigated. In this study, we synthesized [Rh(cod)L]X (L = cod, CH, PhMe; X = SbF, (FSO)N (= FSA), CFBF, CBH) and investigated their phase behaviors, crystal structures, and reactivities. The phase transitions of these salts result in disordered solid-state structures. Moreover, the structural disorder increases with a decrease in the cation symmetry in the SbF salts; [Rh(cod)(PhMe)]SbF exhibits a rotator phase, and the cations in other salts exhibit a dynamic rotational disorder. In contrast, a lower crystal symmetry with less cation disorder is observed for FSA salts. The thermal stabilities and reactivities of these salts were further investigated. FSA salts with arene ligands produce anion-coordinated complexes upon melting, and SbF salts with arene ligands produce [Rh(cod)L']SbF (L' = MeCN and SMe) via an in situ single-crystal-to-single-crystal ligand-exchange reaction.