Syntheses and structures of a four-co-ordinate monomeric dialkylaluminium complex and a cyclic trimeric alkylaluminium propeller complex with a bidentate amide ligand, Al(PhNCH2CH2NH2)Me2 and [Al(µ-PhNCH2CH2NH)Me]3

Abstract

The reaction of AlMe₃ with N-phenylethylenediamine in toluene at 0 °C yielded a mononuclear complex Al(PhNCH₂CH₂CH₂NH₂)Me₂1 as the major product and a trinuclear cyclic complex [Al(µ-PhNCH₂CH₂NH)Me]₃2 as a minor product. The trinuclear complex was obtained as the major product when the reaction was carried out at 25 °C. The crystal structure of 1 and a cis isomer of 2, where all three methyl groups on the aluminium centres occupy the cis-axial positions of a chair conformation, have been determined by single-crystal X-ray diffraction analysis. Compound 1 can be converted into 2 either by heating or by allowing the solution to stand at 23 °C for a few days. Crystal data: 1, orthorhombic, space group P2₁2₁2₁, a= 10.304(3), b= 13.172(5), c= 8.552(3)Å, Z= 4; 2, trigonal, space group P(no. 147, hexagonal setting), a=b= 16.441(7), c= 11.184(3)Å, Z= 2.