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

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 e-caprolactone.