A Bulky Chelating Diamidoaluminum Monohydride - Synthesis, Structure and Reactions with Me_3SnF and Heavy Group 16 Elements

摘要

The bulky chelating diamidoaluminum monohydride [ArN(CH_2)_3NAr]AlH(NMe_3) (Ar = 2,6-iPr_2C_6H_3; 1) was prepared in excellent yield from the reaction of the diamine ArN(CH_2)_3HNAr with a small excess of AlH·NMe_3 in toluene. Subsequent fluorination of 1 with Me_3SnF resulted in the formation of the aluminum monofluoride [ArN(CH_2)_3NAr]AlF(NMe_3) (2). Reaction of 1 with elemental E (E = S, Se and Te) proceeded in toluene with heating to yield the aluminum chalcogenides {[ArNH(CH_2)_3NAr]Al(μ-E)}_2 (E = S (3), Se (4), and Te (5)]. the structures of complexes 1, 2 and 4 have been determined by X-ray diffraction analyses. Compounds 1 and 2 are well-separated monomers with a central aluminum atom in a tetrahedral environment. The diamide ligand [ArN(CH_2)_3NAr]~(2-) chelates the Al atom to form a distorted six-membered AlN_2C_3 ring which features a boat conformation for 1 and a flattened chair conformation for 2. Compound 4, however, is a dimer with a central Al_2Se_2 core bearing an ideal four-membered planar ring and two six-membered AlN_2C_3 rings, both displaying a boat conformation. The latter two rings are arranged perpendicularly to the Al_2Se_2 core in a trans configuration. The IR spectra and ~1H NMR spectroscopic data of compounds 3-5 suggest that the migration of the hydrogen from selenium to one of the nitrogens at the diamide ligand is involved in the course of the reaction.