Unidentate nitrogen base adducts of aluminium trichloride

Abstract

A number of adducts of aluminium(III) chloride with unidentate nitrogen bases have been synthesized and their room-temperature single-crystal structures determined. With piperidine (pip) a mononuclear 1 : 2 adduct is formed, AlCl₃·2pip, in which the nitrogen atoms are axial in a trigonal-bipyramidal array about the metal: Al–N 2.070(5), Al–Cl 2.162(3)–2.190(3)Å. Attempts to crystallize the material from acetonitrile resulted in the formation of [Al{HNC(Me)N(CH₂)₅}₄]Cl₃·MeCN which has implications in the formation of amidines catalysed by AlCl₃; Al–N 1.851–1.857(4)Å. With 2-methylpyridine, 2-diphenylmethylpyridine and quinoline, 1:1 adducts are obtained, the latter being also monosolvated: Al–N 1.942(4), 1.954(4), 1.959(6); Al–Cl (over all three), 2.082(2)–2.112(4)Å. The structure of AlCl₃(thf)(thf = tetrahydrofuran) was also determined: Al–O 1.798(6), Al–Cl 2.098(4), 2.095(3)(× 2)Å.