CHEMICAL ROUTES TO BARIUM-CERIUM OXIDES - THE QUEST FOR MIXED-METAL PRECURSORS - MOLECULAR-STRUCTURE OF BA4CE2(MU(6)-O)(THD)(4) (MU(3)-OPRI)(8)(OPRI)(2)

Various synthetic routes to Ba-Ce mixed-metal species have been invest igated No reaction was observed between Ce-2(OPri)(8)((PrOH)-O-i)(2) ( 1) and barium isopropoxide. The enhanced acidity of the alcohol molecu les of 1 has been used as a means to access to Ba-Ce species and to fi x the stoichiometry between the metals. Ba2Ce4(OPri)(20) (2) has been obtained. This species is unstable in the presence of isopropanol givi ng BaCe4(OPri)(18) (3). The reaction between 1 2,2,6,6-tetramethylhept ane-3,5-dione (thdH) and barium isopropoxide gives Ba4Ce2(mu(6)-O)(thd )(4)(mu(3)-OPri)(8)(OPri)(2) (4) independently of the stoichiometry us ed for the reac tion. The reactions between 1, barium isopropoxide and acetylacetone are more complex and different compounds, namely Ba2Ce2 O(acac)(2)(OPri) (5) or BaCe2(acac)(OPri)(9) (6) are formed depending on the experimental conditions. All compounds have been characterized by elemental analysis, FT-IR, H-1 and C-13 NMR. 4 was also characteriz ed by X-ray diffraction. Hydrolysis-polycondensation reactions have be en estimated for 4 and for 6. (C) 1998 Elsevier Science Ltd. All right s reserved.