AGGREGATION OF METALATED ORGANICS BY HYDROGEN-BONDING - SYNTHESIS AND CRYSTAL-STRUCTURES OF 2-AMINOPHENOXY-ALUMINUM AND SALEN-ALUMINUM LIGAND-SEPARATED ION-PAIRS

Ion separation of Al(2-H2NC6H4O)(2)Cl and of Al(salen)X [X(-) = Cl-, I-, CF3SO3-; H(2)salen = N,N'-bis(salicylidene)ethylenediamine] is promoted by the addition of the strong Lewis base HMPA (hexamethylphosphoramide) which stabilizes the resulting cationic aluminum species. The X-ray structure of [Al(2-H2NC6H4O)(2)(HMPA)(2)]+C1(-) (2a) shows it to be a dimer formed by two [Al(2-H2NC6H4O)2(HMPA)2](+) cations connected via two NH hydrogen bonded Cl- ions. [Al(salen)(HMPA)(2)]Cl-+(-) (4a) and [Al(salen)(HMPA)(2)](CF3SO3-)-C-+ (7a) also form dimeric aggregates but by CH ... X hydrogen bonds between the salen imine and ethylene protons and the anions, X(-). In contrast to the Cl- and CF3SO3- derivatives, [Al(salen)(HMPA)2]I-+(-) (9) forms a three-dimensional ionic lattice structure rather than distinct aggregates. If [AlCL(4)](-) is used as the counterion the weakly Lewis-basic THF is sufficient to stabilize the aluminum cation, as demonstrated by the structure of [Al(salen)(THF)(2)](+) [AlCl4](-) (10). This compound also forms an ionic lattice-type structure. The crystal data are as follows. 2a: C12H24Al0.5Cl0.5N4O2P, orthorhombic, Pnnm; a = 14.675(3); b = 15.059(3), c = 15.132(3) Angstrom; Z = 8. 4a: C56H100Al2Cl2N16O8P4 . 2C(4)H(8)O, triclinic, P (1) over bar; a = 10.821(2), b = 11.234(2), c = 32.974(7) Angstrom; alpha = 84.99(3), beta = 82.73(3), gamma = 81.38(3)degrees; Z = 2. 7a: C29H50AlF3N8O7P2S . 2C(7)H(8), monoclinic, C2/c; a = 29.591(6), b = 17.102(3), c = 18.018(4) Angstrom, beta = 97.98(3) Angstrom; Z = 8. 9: C56H100Al2I2N16O8P4, monoclinic, Pn; a 10.552(2), b = 26.060(5), c = 14.030(3) Angstrom, beta = 104.39(3)degrees; Z = 2. 10: C24H30Al2Cl4N2O4, monoclinic, C2/c; a = 28.474(6), b = 13.896(3), c = 15.532(3) Angstrom; beta = 111.80(3)degrees, Z = 8.