The Schiff base ligands [3,5-But2-2-(OH)C6H2CHNL] [L = CH2CH2NMe2 (1a), 2-(PhO)C6H4 (1b), 2-CH2C5H3N (1c), 8-C9H6N (quinoline) (1d) and 2-(PPh2)C6H4 (1e)] are accessed in good yields (>85%) via standard imine condensation reactions. Reaction of 1a–e with Me3Al at room temperature affords the corresponding complexes [(3,5-But2-2-(O)C6H2CHNL)AlMe2] (2a–e);
in the case of L = 8-quinoline, the same reaction conducted in refluxing toluene affords binuclear [3,5-But2-2-(O)C6H2CHMeN-8-C9H6N]AlMe}2 (3) by methyl migration from metal to ligand. Further reaction of the dimethyl compounds with B(C6F5)3 in CD2Cl2 or C6D6 affords the cationic systems [(3,5-But2-2-(O)C6H2CHNL)AlMe]+ (4a–e). The crystal structures of 2a, 2c, 2e and 3 have been determined. In 2a and 2c
the respective ligands bind to the metal centre via all three heteroatoms, the aluminium having a trigonal bipyramidal geometry, whereas in 2e coordination is via nitrogen and oxygen only, and the aluminium is tetrahedral. Complex 3 has a dimeric structure with the ligand adopting both tridentate and binucleating roles; the aluminium centres are trigonal bipyramidal.
通过标准的
亚胺缩合反应,可以获得希夫碱
配体[3,5-But2-2-(OH)C6H2CHNL] [L = CH2CH2NMe2 (1a)、2-(PhO)
C6H4 (1b)、2-CH2C5H3N (1c)、8-
C9H6N(
喹啉)(1d) 和 2-(PPh2) (1e)],收率良好(大于 85%)。室温下,1a-e 与 Me3Al 反应生成相应的配合物[(3,5-But2-2-(O)C6H2CHNL)AlMe2](2a-e);在 L = 8-
喹啉的情况下,在回流
甲苯中进行相同的反应,通过从
金属到
配体的甲基迁移,生成双核[3,5-But2-2-(O)C6H2CHMeN-8- ]AlMe}2(3)。二甲基化合物与 B(
C6F5)3 在 CD2Cl2 或 C6D6 中进一步反应,得到阳离子体系[(3,5-But2-2-(O)C6H2CHNL)AlMe]+(4a-e)。2a、2c、2e 和 3 的晶体结构已经确定。在 2a 和 2c 中,各自的
配体通过所有三个杂原子与
金属中心结合,铝的几何形状为三叉双锥,而在 2e 中,
配体仅通过氮和氧配位,铝的几何形状为四面体。配合物 3 具有二聚体结构,
配体同时具有三价和双核作用;铝中心为三棱双锥体。