Structural aspects and ring opening polymerization of ε-caprolactone using mono- and di-aluminum compounds incorporating bidentate pyrrole-morpholine ligands

• Published in: Journal of organometallic chemistry Vol. 804; pp. 35 - 41
• Main Authors: Hsiao, Hung-Chang, Datta, Amitabha, Chen, Yun-Fan, Chang, Weilun, Lee, Ting-Yu, Lin, Chia-Her, Huang, Jui-Hsien
• Format: Journal Article
• Language: English
• Published: LAUSANNE Elsevier B.V 15.02.2016; Elsevier
• Subjects: Aluminum; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Physical Sciences; Pyrrole-morpholine; Science & Technology; ε-caprolactone; Pyrrole-morpholine; ε-caprolactone; Aluminum; CYCLIC ESTERS; FUNCTIONALIZED INDENYL LIGANDS; EXCELLENT INITIATORS; CRYSTAL-STRUCTURES; ALKYL COMPLEXES; RACEMIC LACTIDE; GROUP-4 COMPLEXES; MIXED-DONOR; epsilon-caprolactone; CATALYTIC-ACTIVITY; CHIRAL LEWIS-ACID
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2015.12.030

A series of Al-compounds incorporating the bidentate pyrrole-morpholine precursor C4H3NH [2-CH2N(CH2CH2)2O] (1) and aluminum-alkyl have been conveniently synthesized and characterized by 1H and 13C NMR spectroscopy. Reacting one or two equivalents of 1 with AlMe3 in toluene afforded AlMe2{C4H3N [2-CH2N(CH2CH2)2O]} (2) and AlMe{C4H3N [2-CH2N(CH2CH2)2O]}2 (3), respectively, in moderate yield. Furthermore, compound (4), AlMe2{C4H3N [2-CH2N(CH2CH2)2O]}·AlMe3, was acquired either by the combination of 2 and one equivalent of AlMe3 or directly from the reaction between 1 and two equivalents of AlMe3. The molecular structures of 1, 2, and 4, were determined by single crystal X-ray diffractometry in solid state, showing a distorted tetrahedral arrangement around the Al atom in 2 and 4. All the aluminum compounds could effectively initiate the ring-opening polymerization (ROP) of ε-caprolactone in a well-controlled manner with molecular weight distributions (PDI = 1.03–1.49). [Display omitted] •Bi-dentate pyrrole-morpholine ligand.•Mono-aluminum and di-aluminum compounds.•Ring-opening polymerization of ε-caprolactone.