A Bulky Chelating Diamidoaluminum Monohydride − Synthesis, Structure and Reactions with Me₃SnF and Heavy Group 16 Elements

The bulky chelating diamidoaluminum monohydride [ArN(CH 2 ) 3 NAr]AlH(NMe 3 ) (Ar = 2,6‐ i Pr 2 C 6 H 3 ; 1 ) was prepared in excellent yield from the reaction of the diamine ArNH(CH 2 ) 3 HNAr with a small excess of AlH 3 ·NMe 3 in toluene. Subsequent fluorination of 1 with Me 3 SnF resulted in the formation of the aluminum monofluoride [ArN(CH 2 ) 3 NAr]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 ) 3 NAr]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 ) 3 NAr] 2− chelates the Al atom to form a distorted six‐membered AlN 2 C 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 2 Se 2 core bearing an ideal four‐membered planar ring and two six‐membered AlN 2 C 3 rings, both displaying a boat conformation. The latter two rings are arranged perpendicularly to the Al 2 Se 2 core in a trans configuration. The IR spectra and 1 H 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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)