Synthesis and reactions of aluminum sulfonamide alkyls and hydride

Article abstract of DOI:10.1021/om0611296

Aluminum compounds supported by a sulfonamide ligand are described. Reaction of AlEt₃ with 1 equiv of the sulfonyl amine ArNH(SO ₂-p-Tol) (Ar = 2,6-iPr₂C₆H₃, Toi = 4-MeC₆H₄) yielded the dimeric aluminum species [ArN(SO₂-p-Tol)AlEt₂]₂ (1), and reactions of AlEt₃ and AlH₃·NMe₃ with 2 equiv of ArNH(SO₂-p-Tol) yielded the aluminum bis(sulfonamide) species [ArN(SO₂-p-Tol)]₂AlEt (2) and [ArN(SO₂-p-Tol)] ₂AlH (3). The iodide species [ArN(SO₂-p-Tol)AlI ₂]₂ (4) and [ArN(SO₂-p-Tol)]₂AlI (5) were prepared by the reaction of 1 and 2 with iodine. Reaction of 3 with PhNH₂, HCCPh, and Ph₂CO yielded [ArN(SO ₂-p-Tol)]₂AlNHPh (6), [ArN(SO₂-p-Tol)] ₂AlCCPh (7), and [ArN(SO₂-p-Tol)]₂AlOCHPh ₂ (8). Treatment of 6 with BuⁿLi in n-hexane led to a ligand transfer reaction to give the dimeric lithium salt [ArN(SO ₂-p-Tol)Li(THF)₂]₂ (9). Compounds 1-4 and 7-9 have been characterized by X-ray single-crystal analysis, which disclosed that the aluminum mono(sulfonamide) compounds adopt a dimeric NSOAlNSOAl eight-membered-ring structure while the aluminum bis(sulfonamide) species are monomeric species with a five-coordinate aluminum center. Interestingly, the lithium salt 9 has a dimeric structure with an OSOLiOSOLi eight-membered-ring core. Compounds 3 and 8 are found to be active for lactide polymerization at high temperature.