Copper(II) complexes with imino phenoxide ligands: synthesis, characterization, and their application as catalysts for the ring-opening polymerization of rac-lactide

Abstract

Four new copper complexes based on bidentate imino phenoxide ligands were synthesized and characterized by IR, UV–Vis spectroscopy, ESI mass spectrometry, single crystal X-ray diffraction, and electrochemistry. The crystal structures revealed that the copper(II) atoms are surrounded by phenolate oxygen and imine nitrogen atoms of two ligands in a distorted square-planar geometry. The existence of ligand-centered, as well as Cu(II)-centered quasi-reversible and reversible redox reactions are observed in the cyclic voltammetry experiments of all the complexes. All complexes are able to catalyze the ring-opening polymerization of rac-lactide yielding polymers with moderate molecular weights and moderately broad molecular weight distributions.Graphical abstract Electronic supplementary materialThe online version of this article (doi:10.1007/s00706-016-1830-7) contains supplementary material, which is available to authorized users.

Palladium complexes containing imino phenoxide ligands: synthesis, luminescence, and their use as catalysts for the ring-opening polymerization of rac-lactide

“…2 , right), i.e. the activities of the catalysts are slightly higher than those found for the copper(II) homologue complexes we reported previously [ 12 ].

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“…Complex 1 crystallizes in the monoclinic space group P 2 1 / n , complex 2 in the triclinic space group P , both with one half formula units in the asymmetric unit with the palladium atom as the inversion centre. Complex 2 is isostructural to the homologues copper(II) complex [ 12 ]. The palladium atom is coordinated by two nitrogen and two oxygen atoms with an angular sum of exact 180° indicative for a perfect planar coordination.…”

“…Ligands L1–L3 were prepared according to literature-reported procedures [ 44 , 45 ]. Polymerization experiments and characterization of the polymers were performed according to described procedures [ 12 ].…”

“…Hence, reports from almost all areas of coordination chemistry have been published up to now. Such complexes have found applications in catalysis or biochemistry or feature interesting structural, magnetic, photophysical or electrochemical properties [ 3 – 12 ].…”

Copper(II) complexes bearing cyclobutanecarboxylate and pyridine ligands: a new series of dinuclear paddle-wheel complexes

“…In the UV-Vis spectra, each complex features a broad absorption at around 700 nm with a low extinction coefficient of around 150 mol −1 dm 3 cm −1 which is characteristic of d-d transitions [10,15]. For 1 and 2, π-π* transitions of the pyridine moieties are found at ~ 255 nm (Figs.…”