Investigations on the interaction of dichloroaluminum carboxylates with lewis bases and water: An efficient road toward oxo- and hydroxoaluminum carboxylate complexes

摘要

A series of dichloroaluminum carboxylates [Cl _2Al(O _2CR)] _2 (were R = Ph (1a), ~tBu (1b), CHCH _2 (1c) and C _(11)H _(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H _2O performed. Compounds [Cl _2Al(O _2CR)] _2 and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl _2Al(O _2CR)] _2 equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl _2Al(λ _2-O _2CR)(py-Me) _2] [R = Ph (3a), ~tBu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H _2O in THF-toluene solution lead to oxo carboxylates [(Al _3O)(O _2CR) _6(THF) _3] [AlCl _4] [where R = Ph (4a _(THF)), ~tBu (4b _(THF)), and C _(11)H _(23) (4d _(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl) _2(OH)(O _2CC _2H _3) _2 (THF) _4][AlCl _4] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al _2(OH)(O _2C ~tBu) _2(MeCN) _6][AlCl _4) _3] (6). All compounds were characterized by elemental analysis, ~1H, ~(27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a _(THF), 4b _(THF), 4b _(py-Me)′, 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H _2O and neutral donor ligands.