Thermal properties and crystal structures of manganese(III)-salen complexes with the Tf2N anion [Tf2N = bis(trifluoromethanesulfonyl)amide)]

A series of salts comprising cationic manganese(III)-salen complexes and the Tf2N anion has been prepared (salen = N,N′-bis(salicylideneaminato)ethylene, Tf2N = bis(trifluoromethanesulfonyl)amide) to investigate the effects of axial ligands and substituents on their thermal properties. [Mn(salen)L2][Tf2N] (L = H2O, pyridine) and their 5-butoxysalen analogs undergo thermal desorption of the axial ligands, followed by decomposition above 250 °C. The pyridine complexes exhibit two-step ligand desorption, corresponding to the formation of a dimer and later, desorption from the dimer. Complexes with L = 3-butylpyridine and N-butylimidazole melt at 97.6 and 132.7 °C, respectively, before ligand desorption. Crystal structures of these and related complexes have been determined. [Mn(salen)(3,3′-bipyridine)][Tf2N] is a coordination polymer with higher thermal stability.

Graphical abstractA series of salts comprising cationic manganese(III)–salen complexes and the Tf2N anion have been prepared. [Mn(salen)L2][Tf2N] (L = H2O, Pyridine) and their 5–butoxysalen analogues undergo thermal desorption of the axial ligands, followed by decomposition. The pyridine complexes exhibit two-step ligand desorption. Complexes with L = 3-butylpyridine and N-butylimidazole melt near 100 °C or above, before ligand desorption. Crystal structures of these and related salts have been determined.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Manganese(III)-salen salts with Tf2N prepared and crystallographically characterized. ► [Mn(salen)L2][Tf2N] with alkylated axial ligands (L) melted near 100 °C or above. ► Thermal behaviors of the salts strongly depended on the axial ligands.