TOWARD UNUSUAL AL-O COMPOUNDS - SYNTHESIS AND MOLECULAR-STRUCTURE OF [AL4O(OCH2CF3)11]- - STRUCTURAL CHARACTERIZATION OF A NOVEL AL4O12 CLUSTER

Reaction of Me3Al with CF3CH2OH in hexane at -78-degrees-C affords the novel crystalline complex [Al4O(H)(OCH2CF3)11] in high yield. The tit le compound crystallizes in the orthorhombic space group Pna2(1), with unit cell parameters a = 16.875(8) angstrom, b = 13.575(5) angstrom, c = 19.423(8) angstrom, V = 4449 angstrom3, Z = 4, and D(calc) = 1.82 g cm-3. Refinement converged at R = 0.072, R(w) = 0.083 for 2837 obser ved reflections (I > 2.5 sigma(I)). While the exterior is dominated by CF3CH2-groups, the core of the molecule consists of an interesting, h igh-oxygen content Al4O12 cluster. Furthermore, it is significant that the coordination sphere of the four core aluminum atoms is constitute d solely by oxygen atoms, each metal atom being five-coordinate and re siding in distorted trigonal bipyramidal environments.