Reactivity of mixed-metal BaCu and BaY beta-diketonatoalkoxides with Lewis bases: Molecular structures of [Ba2Cu(mu(3),eta(2)-OCHMeCH(2)NMe(2))(2)(mu,eta(2)-thd)(2)(eta(2)-thd)(2)((PrOH)-O-i)(2)], [Cu-3(mu(3)-OBu(t))(2)(eta(2)-thd)(3)] and [Ba(eta(2)-thd)(2)(TMEDA)(2)]

Reactions involving Y(thd)(3) and Cu(thd)(2) with barium tert-butoxide or 2-dimethylamino-2-propoxide were investigated. The mixed-metal complexes [YBa3(OBu(t))(6)(thd)(3)] (1) and [BaCu(OBu(t))(2)(thd)(2)](m) (3) (thdH = 2,2,6,6-tetramethylheptane-3,5-dione) were isolated in hexane. Dissolution of 3 in Et(2)O or THF afforded [Cu-3(OBu(t))(3)(thd)(3)] (4) and [Cu(thd)(2)(OBu(t))(2)(THF)(2)] (5), respectively, while [Ba(thd)(2)(TMEDA)(2)] (2) was obtained in the presence of N',N'-tetramethylenediamine. Dissolution of 1 in THF afforded a THF adduct (1a) giving 1 by sublimation at 190 degrees C/10(-3) Torr. By contrast, the reaction between the barium aminoalkoxide and Y(thd)(3) in hexane proceeded directly to the formation of homometallic compounds, whereas with Cu(thd)(2) the mixed-metal compound {Ba2Cu [OCHMeCH(2)NMe(2)](2)(thd)(4)((PrOH)-O-i)(2)} (6) was obtained by crystallization from (PrOH)-O-i. All compounds were characterized by elemental analysis, IR,H-1 NMR, ESR and TGA for the copper species. Compounds 2, 4 and 6 were characterized by single-crystal X-ray diffraction. The [Ba(thd)(2)(TMEDA)(2)] adduct is monomeric. The structures of 4 and 6 consist of triangular aggregates with Cu-3(mu(3)-OBu(t))(2)(mu-OBu(t))(thd)(3) and Ba2Cu(mu(3),eta(2)-OCHMe CH(2)NMe(2))(2)(mu,eta(2)-thd)(2)(eta(2)-thd)(2)((PrOH)-O-i)(2) cores, respectively. Compound 4 exhibits one square planar and two square pyramidal copper centres. The Cu-O bond lengths range from 1.90(2) to 2.27(2) Angstrom, the order of variation being Cu-O(thd) < Cu-mu-OR < Cu-mu(3)-OR. For compound 6, the thd, OR and (PrOH)-O-i ligands are bonded asymmetrically to the three metallic centres. Each barium atom bears a chelating thd ligand, two other thd are bridging-chelating, linking the two barium atoms, and one barium, Ba(2), to the copper atom, respectively. The nitrogen-donor sites of the two mu(3)-aminoalkoxide ligands interact with the copper and Ba(2) centres. The two isopropanol molecules are bonded to the other barium, Ball); the solvate is stabilized by intramolecular hydrogen bonds. This allows the barium atoms to reach high coordination numbers, seven and eight, and the copper atom to be pentacoordinated. The Ba-O bond lengths range from 2.59(1) to 2.87(1) Angstrom. The Ba-N bond distance is 2.85(1) Angstrom. Compounds 4 and 5 are volatile;5 loses its THF upon sublimation to yield 4.