REACTIVITY OF Y3(OR)7CL2(THF)2 WITH ORGANOALUMINUM REAGENTS - FORMATION OF THE YTTRIUM ALUMINUM COMPLEXES Y(OR)3(ALME3)3, Y(OR)3(ALME3)2(THF), AND Y(OR)3(ALME2)CL(THF)2 AND THE HALIDES YCL3(DME)2 AND YCL3(THF)3Y3(OR)7O (R = CME3)

The trimetallic structure of Y3(OCMe3)7Cl2(THF)2 (1), which is typically retained in reactions of yttrium tert-butoxide complexes, was easily disrupted by trimethylaluminum to generate a series of mixed-metal yttrium-aluminum compounds. 1 reacted with AlMe3 in hexanes to form Y[(mu-OCMe3)(mu-Me)AlMe2]3 (2), (Me3CO)(THF)Y-[(mu-OCMe3)(mu-Me)AlMe2]2 (3), and (Me3CO)(Cl)(THF)2Y[(mu-OCMe3)2AlMe2] (4). 2 crystallized from hexanes in the space group P31c with a = 15.842(2) angstrom, c =- 7.9994(14) angstrom, V = 1738.6(4) angstrom3, and D(calcd) = 1.002 Mg/m3 for Z = 2. Least-squares refinement of the model based on 799 reflections (\F(o)\ > 4.0sigma\F(o)\) converged to a final R(F) = 9.9%. 2 can be viewed as a tris(trimethylaluminum) adduct of Y(OCMe3)3, a unit which has not previously been isolated in a monometallic form. An octahedral coordination environment around the yttrium in 2 was generated by three doubly-bridging [(mu-OCMe3)(mu-Me)AlMe2] moieties which contain tetrahedrally-coordinated aluminum. 3 crystallized from toluene in the space group Pca2(1) with a = 14.408(4) angstrom, b = 17.216(3) angstrom, c = 12.186(2) angstrom, V = 3022.7(11) angstrom3, and D(calcd) = 1.153 Mg/m3 for Z = 4. Least-squares refinement of the model based on 1848 reflections (\F(o)\ > 3.0sigma\F(o)\) converged to a final R(F) = 4.5%. The six-coordinate octahedral environment around yttrium in 3 is similar to that of 2, except that THF and a terminal tert-butoxide ligand have replace one of the three [(mu-OCMe3)(mu-Me)AlMe2) units. 4 crystallized from THF/DME (20:1) in space group Pnma with a = 19.752(2) angstrom, b = 12.765(28) angstrom, c = 11.938(10) angstrom, V = 3010(8) angstrom3, and D(calcd) = 1.09 Mg/m3 for Z = 4. Only one chelating aluminum moiety is present in the octahedral coordination sphere of 4, and it differs from those in 2 and 3 in that it contains two bridging tert-butoxide ligands and two terminal methyl groups. YCl3(DME)2 (5) was also obtained from the 1/AlMe3 reaction mixture by crystallization from THF/DME (3:1). 5 crystallized in space group P2(1)/c with a = 11.343(5) angstrom, b = 8.855(3) angstrom, c = 15.617(9) angstrom, beta = 104.59(4)degrees, V = 1518.1(12) angstrom3, and D(calcd) = 1.64 Mg/m3 for Z = 4. Least-squares refinement of the model based on 1659 reflections (\F(o)\ > 3.0 sigma\F(o)\) converged to a final R(F) = 3.2%. The seven-coordinate complex adopts a distorted pentagonal bipyramidal geometry with chloride ions in the axial positions. The reaction of LiAlMe4 with Y3(OCMe3)7Cl2(THF)2 generated the tetrametallic complex [(THF)3Y(mu-Cl)3]Y3(mu-OCMe3)(mu-OCMe3)3(OCMe3)3-(mu4-O) (6). 6 crystallized from toluene in the space group R3BAR with a = 14.615(3) angstrom, c = 50.993(12) angstrom, V = 9433(3) angstrom3, and D(calcd) = 1.274 Mg/m3 for Z = 6. Least-squares refinement of the model based on 1344 reflections (\F(o)\ > 6.0sigma\F(o)\) converged to a final R(F) = 7.8%. 6 can be viewed as a YCl3(THF)3 unit attached to a trimetallic yttrium tert-butoxide complex similar to 1. The complex contains a tetrahedral arrangement of yttrium atoms surrounding an internal mu4-oxide ligand, and the yttrium trichloride unit is seven-coordinate as in 5.