摘要
Substituted bi- and tri-dentate pyrrole-piperazine precursors, C 4 H 3 NH-[2-CH 2 N(CH 2 CH 2 ) 2 NPh] (1) and C 4 H 2 NH-{2,5-[CH 2 N(CH 2 CH 2 ) 2 NPh] 2 } (2) are synthesized and the corresponding Al derivatives are afforded systematically in moderate yield. Reacting one equivalent of 1 with AlMe 3 in toluene generates an aluminum dimethyl compound, AlMe 2 {C 4 H 3 N-[2-CH 2 N(CH 2 CH 2 ) 2 NPh]} (3) in satisfactory yield. Similarly, the reaction of two equivalents of 1 and AlMe 3 affords [AlMe{C 4 H 3 N[2-CH 2 N(CH 2 CH 2 ) 2 NPh]} 2 ] (4), which on repeating recrystallization in dichloromethane produces [AlMe{C 4 H 3 N[2-CH 2 N(CH 2 CH 2 ) 2 NPh]} 2 [NH(CH 2 CH 2 ) 2 NPh]] (4a) in small quantity. Furthermore, reactions of 3 with one equivalent of 1,3-diphenylpropane-1,3-dione and 2,6-diisopropylphenol in toluene results in the aluminum methyl compounds, [AlMe(PhCOCHCOPh){C 4 H 3 N[2-CH 2 N(CH 2 CH 2 ) 2 NPh]}] (5) and [AlMe(O-2,6- i Pr 2 C 6 H 3 ){C 4 H 3 N[2-CH 2 N(CH 2 CH 2 ) 2 NPh]}] (6), respectively. Interestingly on fractional recrystallization, compound 6 affords the μ 2 -oxo bridged dialuminum compound, [{Al(O-2,6- i Pr 2 C 6 H 3 ){C 4 H 3 N[2-CH 2 N(CH 2 CH 2 ) 2 NPh]}} 2 (μ-O)] (6a) while exposed to air. Additionally, the combination of the tridentate pyrrole ligand 2 and one equivalent of AlMe 3 in toluene produces [AlMe 2 {C 4 H 2 N{2,5-[CH 2 N(CH 2 CH 2 ) 2 NPh] 2 }}] (7). Compounds 3, 4a, 5, and 6a are subjected to X-ray diffraction analysis to ensure the geometry around the Al atom. Overall, the influences of the new pyrrole-piperazine incorporated N-donor precursors on the structural factors, reactivity with small organic molecules and the associated mechanistic details are discussed.