Investigation of the properties and thermochemistry of some complexes of aluminium hydride with tertiary amines and diamines

Abstract

Four new complexes of aluminium hydride with quinuclidine (1 : 1 and 2 : 1), 1,4-dimethylpiperazine (1 : 1), and NNN′N′-tetramethyl-o-phenylenediamine (1 : 1) have been synthesised and characterised by chemical analysis, i.r. spectroscopy, and molecular weight measurements. The standard heats of formation of these and several other complexes of aluminium hydride have been derived from their heats of reaction with aqueous hydrochloric acid at 298·2 K. The following values were obtained for ΔH_f°/kJ mol^–1: HC[(CH₂)₂]₃N,AlH₃ 109; {HC[(CH₂)₂]₃N}₂,AlH₃ 169; Me₂N(CH₂)₂NMe₂,AlH₃ 108; Me₂N(CH₂)₃NMe₂,AlH₃ 177; MeN[(CH₂)₂]₂NMe,AlH₃ 163; o-C₆H₄(NMe₂)₂,AlH₃ 175. The results are discussed in terms of the structures and stabilities of the complexes.