Magnesium complexes supported by pyrrolylligands: syntheses, characterizations, and catalytic activities towards the polymerization of ε-caprolactone

Abstract

The syntheses, structures and catalytic activities of five magnesium complexes supported by HL1 (HL1 = N-(1H-pyrrol-2-ylmethylene)(2-pyridinyl)methanimine), HL2 (HL2 = N-(1H-pyrrol-2-ylmethylene)-2-pyridineethanimine), HL3 (HL3 = 2-pyrrolecarbaldmethylimine), HL4 (HL4 = N-((1H-pyrrol-2-yl)methylene)(phenyl)methanimine) and HL5 (HL5 = N-((1H-pyrrol-2-yl)methylene)-2-phenylethanimine) are described. Treatment of MgⁿBu₂ with 2 equiv. of HL1, HL2, HL3, HL4 and HL5, respectively, results in the formation of Mg(L1)₂ (1), Mg(L2)₂ (2), Mg(L3)₂(THF)₂ (3), Mg(L4)₂(THF)₂ (4) and Mg(L5)₂(THF)₂ (5). All complexes have been characterized by elemental analyses and NMR studies. The solid-state structures of complexes 2, 3, and 4 have been further established by single X-ray crystallography. All complexes were found to be active catalysts for the ring-opening polymerization of ε-caprolactone.