In situ Monitoring of the Formation of [Bis(acetylacetonato)manganese(II)] Complexes

[Bis(acetylacetonato)manganese(II)] complexes are important precursors for the synthesis of catalytic MnO nanoparticles. However, the mechanism of the formation of these materials still remains unknown. In this work, a combination of ex situ and synchrotron-based in situ powder X-ray diffraction with in situ pH, conductivity, and turbidity measurements was applied to investigate the concentration-dependent formation of [Mn(acac)(2)(H2O)(2)]; interestingly [Mn(acac)(2)(H2O)(2)] undergoes an expansion of the unit cell during the synthesis as well as upon heating. Increasing the temperature to 80 degrees C caused the conversion of solid [Mn(acac)(2)(H2O)(2)] to the trimer compound [Mn(acac)(2)](3), which occurs ex situ (in solid state), but is hindered in solution. [Mn(acac)(2)(H2O)(2)] emits light in the blue-green spectral range with emission maximum at 520 nm, measured in situ under real reaction conditions during its formation due to the instability of this compound.