Tetranuclear manganese(ii) complexes of sulfonylcalix[4]arene macrocycles: synthesis, structure, spectroscopic and magnetic properties

Abstract

Two tetranuclear manganese(II) complexes {K⁺[Mn₄(ThiaSO₂)₂(OH)]⁻} (1) and {K⁺[Mn₄(ThiaSO₂)₂(F)]⁻} (2) have been synthesized under solvothermal conditions in methanol with p-tert-butylsulfonylcalix[4]arene (ThiaSO₂). For both complexes, the structure has been established from single-crystal X-ray diffraction. The two complexes are best described as manganese squares sandwiched between two thiacalixarene macrocycles. In both complexes, in the center of the square formed by the four manganese(II) atoms, the unexpected presence of μ₄-OH⁻ or μ₄-F⁻ gives a negative charge to the cluster. The two tetranuclear complexes exhibit strong orange luminescence behavior resulting from the symbiosis between the ThiaSO₂ and the Mn²⁺. Despite similar chemical formulation, (1) and (2) present difference in emission intensity and lifetime τ.