Thermal dehydration of Y(TFA)(3)(H2O)(3): Synthesis and molecular structures of Y(mu, eta(1):eta(1)-TFA)(3)(THF)(H2O) (1 infinity) center dot THF and Y-4(mu(3)-OH)(4)(mu, eta(1):eta(1)-TFA)(6)(eta(1)-TFA) (eta(2)-TFA)(THF)(3)(DMSO)(H2O) center dot 6THF (TFA = trifluoroacetate)
Résumé
In order to obtain a better anhydrous precursor for various applications in materials science and catalysis, thermal dehydration reactions of Y(TFA)(3)(H2O)(3) (TFA = trifluoroacetate) (A) were investigated. Thermal treatment of A at different temperatures under vacuum (5 x 10(-2) MM) for several hours failed to give totally anhydrous yttrium trifluoroacetate (as indicated by IR). Two different complexes, a partially dehydrated [Y(mu, eta(1):eta(1)-TFA)(3)(THF)(H2O)(1 infinity)center dot THF (1) and a partially hydrolyzed [Y-4(mu(3)-OH)(4)(mu, eta(1):eta(1)-TFA)(6)(eta(1)-TFA)(eta(2)-TFA)(THF)(3)(DMSO)(H2O)] center dot 6THF (2), were obtained with good and moderate yield, respectively, by crystallization of two different thermally treated batches of A from THIP (or THF + DMSO) at room temperature. More efficient dehydration of A could be achieved at 200 degrees C in a furnace, the obtained anhydrous yttrium tris-trifluoroacetate giving Y(TFA)3(THF)2 (3) on crystallization from THF. All the products were characterized by elemental analyses, FT-IR and H-1 NMR spectroscopy as well as thermo-gravimetric analysis. In addition, single crystal X-ray structures are reported for 1 and 2, which show either a terminal (eta(1) and eta(2)) or bridging (mu, eta(1):eta(1))bonding behavior of the TFA ligand.