Thermal Properties and Crystal Structures of Rhenium(I) Carbonyl Complexes with Tridentate Ligands: Preparation of Rhenium-Containing Ionic Liquids.

Although the coordination chemistry of rhenium complexes is a rapidly expanding research field, little is known about their thermal properties. In this study, we synthesized several rhenium tricarbonyl complexes with tridentate ligands (L) having S or N as donor atoms, fac-[Re(CO)3L]X (X = Tf2N [= bis(trifluoromethanesulfonyl)amide)], PF6) and fac-[Re(CO)3LCl], and investigated their thermal properties and crystal structures. The Tf2N salts were room temperature ionic liquids. The S-coordinated complexes, having longer coordination bonds, were less thermally stable than the N-coordinated complexes. Even though fac-[Re(CO)3LCl] are bidentate coordination complexes, they were thermally more stable than the isomeric tridentate complexes fac-[Re(CO)3L]Cl.