Synthesis, characterization, and properties of three europium 2-propoxides:: [Eu4(OPri)10(HOPri)3]*2HOPri, Eu5O(OPri)13, and EuAl3(OPri)12

The reaction of Eu metal with HOPri/toluene solutions yielded the mixed Eu2+/Eu3+ alkoxide [Eu-4(OPri)(10)(HOPri)(3)].2HOPr(i) (1), in contrast to the other lanthanide metals, which exclusively yield trivalent lanthanide ions in the alkoxides formed. Metathesis between EuCl3 and 3KOPr(i) and stoichiometric hydrolysis yielded the square-pyramidal Eu5O(OPri)(13) (2), and metathesis with EuCl3 and 3KAI(OPri)(4) gave EuAl3(OPri)(12) (3). The structures of these compounds were determined by single-crystal X-ray diffraction. IR spectroscopic studies showed that the solid-state molecular structure of the three alkoxides remained close to intact in solution. Further characterizations were made with UV-vis spectroscopy, differential scanning calorimetry, and solubility studies. It was also found that 1 can be converted to 2 by oxidation with dioxygen, but 2 was not reduced by Eu metal to 1. The reactions of 2 and 1 with Al-4(OPri)(12) in toluene/HOPri solvent were studied by IR and UV-vis spectroscopy; 2 reacted completely to form 3 in 2 h at 75 degreesC, while 1 reacted to yield 3 and other unidentified Eu2+ containing product(s) in the same time.