THE USE OF TETRADENTATE (N2O2) LIGANDS TO FORM MONOMERIC, TRIMETALLIC ALUMINUM COMPLEXES

Members of the SalanH(4) class of tetradentate (-N2O2) ligand, N,N'-bis(o-hydroxybenzyl)-1,2-diaminoethane (SaleanH(4)), N,N'-bis(o-hydroxybenzyl)-1,3-diaminopropane (SalpanH(4)), N,N'-bis(o-hydroxybenzyl)-1,2-diaminobenzene (SalophanH(4)), and N,N'-bis(o-hydroxybenzyl)-1,2-diamino-4,5-dimethylbenzene (SalomphanH(4)), demonstrate a wide range of chemistry with AlMe(3). For instance, SalpanH(4) will react with 1 and 2 equiv of AlMe(3) to produce the complexes SalpanH(2)(AlMe) (1) and [SalpanAl(AlMe(2))](2) (2), respectively. When 3 equiv of AlMe(3) is added to the appropriate ligand, the novel trimetallic derivatives Salean(AlMe)(A1Me(2))(2) (3), Salpan(AlMe)(AlMe(2))(2) (4), Salophan(AlMe)(AlMe(2))(2) (5), and Salomphan(AlMe)(AlMe(2))(2) (6) result. A general feature of 3-6 is the presence of a rigid solution-state geometry as evidenced by the H-1 NMR. A crystallographic study of 3 has shown that the molecules are comprised of a central AlMe group coordinated in a planar array to the nitrogens and oxygens of the ligand. The two AlMe(2) groups each bridge an oxygen and nitrogen atom. The overall morphology of 4 and 5 is similar to that shown for 3. However, structural characterization of 4 and 5 indicates that the AlMe(2) groups are inequivalent, with one bridging the two oxygens and the other bridging the two nitrogens. Crystal data for 3: C21H31Al3N(2)O(2), space group P ($) over bar 1 (No. 2) with a = 7.946(3) Angstrom, b = 9.662(3) Angstrom, c = 15.804(6) Angstrom, alpha = 89.192(8)degrees, beta = 84.434(6)degrees, gamma = 79.926(4)degrees, V = 1189.0(7) Angstrom(3) and Z = 2. With 253 parameters refined on 2954 reflections having F > 4.0 psi(F), the final R values were R = 0.0667 and R(w) = 0.0651. Crystal data for 4: C44H66Al6N4O4, space group P ($) over bar 1 (No. 2) with a = 7.821(7) Angstrom, b = 17.890(15) Angstrom, c = 18.668(16) Angstrom, alpha = 89.10(4)degrees, beta = 89.86(4)degrees, gamma = 89.78(5)degrees, V = 2612(4) Angstrom(3), and Z = 2. With 523 parameters refined on 2068 reflections having F > 4.0 sigma(F), the final R values were R = 0.0690 and R(w) = 0.0691. Crystal data for 5: C39H47Al3N2O2, space group monoclinic P2(1) (No. 4) with a =10.881(7) Angstrom, b = 17.170(10) Angstrom, c = 11.288(7) Angstrom, beta = 113.275(12)degrees, V = 1937(2) Angstrom(3) and Z = 2. With 401 parameters refined on 4313 reflections having F > 4.0 sigma(F), the final R values were R = 0.0619 and R(w) = 0.0642.