A series of aluminium derivatives containing substituted bidentate and symmetrical tridentate pyrrolyl ligands, [C4H3NH(2-CH2NHtBu)] and [C4H2NH(2,5-CH2NHtBu)2], in toluene or diethyl ether were synthesized. Their reactivity and application for the ring opening polymerization of ε-caprolactone have been investigated. The reaction of AlMe3 with one equiv. of [C4H3NH(2-CH2NHtBu)] in toluene at room temperature affords [C4H3N(2-CH2NHtBu)]AlMe2 (1) in 70% yield by elimination of one equiv. of methane. Interestingly, while reacting AlMe3 with one equiv. of [C4H3NH(2-CH2NHtBu)] in toluene at 0 °C followed by refluxing at 100 °C, [{C4H3N(2-CH2NtBu)}AlMe]2 (2) has been isolated via fractional recrystalliztion in 30% yield. Similarly, reacting AlMe3 with two equiv. of C4H3NH(2-CH2NHtBu) generates [C4H3N(2-CH2NHtBu)]2AlMe (3) in a moderate yield. Furthermore, complex 1 can be transformed to an aluminium alkoxide derivative, [C4H3N(2-CH2NHtBu)][OC6H2(-2,6-tBu2-4-Me)]AlMe (4) by reacting 1 with one equiv. of HOC6H2(-2,6-tBu2-4-Me) in toluenevia the elimination of one equiv. of methane. The reaction of AlR3 with one equiv. of [C4H2NH(2,5-CH2NHtBu)2] in toluene at room temperature affords [C4H2N(2,5-CH2NHtBu)2]AlR2 (5, R = Me; 6, R = Et) in moderate yield. Surprisingly, from the reaction of two equiv. of [C4H2NH(2,5-CH2NHtBu)2] with LiAlH4 in diethyl ether at 0 °C, a novel complex, [C4H2N(2-CH2NtBu)(5-CH2NHtBu)]2AlLi (7) has been isolated after repeating re-crystallization. Furthermore, reacting one equiv. of C4H2NH(2,5-CH2NHtBu)2 with AlH3·NMe3 in diethyl ether generates an aluminium dihydride complex, [C4H2N(2,5-CH2NHtBu)2]AlH2 (8), in high yield. Additionally, treating 8 with one equiv. of HOC6H2(-2,6-tBu2-4-Me) in methylene chloride produces [C4H2N(2,5-CH2NHtBu)2][OC6H2(-2,6-tBu2-4-Me)]AlH (9) with the elimination of one equiv. of H2. The aluminium alkoxide complex 4 shows moderate reactivity toward the ring opening polymerization of ε-caprolatone in toluene.