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, C 6 H 6 , PhMe; X = SbF 6 , (FSO 2 ) 2 N (= FSA), CF 3 BF 3 , CB 11 H 12 ) 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 6 salts; [Rh(cod)(PhMe)]SbF 6 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 6 salts with arene ligands produce [Rh(cod)L' 2 ]SbF 6 (L' = MeCN and SMe 2 ) via an in situ single-crystal-to-single-crystal ligand-exchange reaction.