Reported are the synthesis, characterization, and crystal structures of two mixed‐ligand copper(II) complexes containing bis[N‐(2,6‐diisopropylphenyl)imino]acenaphthene (o,o′‐iPr2C6H3‐BIAN). In both complexes, namely [Cu(AcOH)(o,o′‐iPr2C6H3‐BIAN)Cl2] (1) and [Cu(acac)(AcOH)(o,o′‐iPr2C6H3‐BIAN)](ClO4) (2) (acac = acetylacetonate and AcOH = acetic acid), the copper ions are in a distorted square‐pyramidal coordination environment with an acetic acid molecule in each apical position. The two imine nitrogen atoms of o,o′‐iPr2C6H3‐BIAN occupy the basal plane with the two chloride atoms and the two oxygen atoms of acac in complexes 1 and 2, respectively. Complex formation results in certain structural changes inside the rigid N−N ligand. Such changes led to an increased planarity of the o,o′‐iPr2C6H3‐BIAN backbone, and produced a nearly perpendicular angle between the naphthalene and the aromatic imine planes. In complex 2, the more perpendicular arrangement of the o,o′‐diisopropylphenyl groups shielding the copper centre was structurally allowed by the elongation of one of the metal‐to‐ligand bonds and by the relatively larger N−Cu−N bite angle. Also discussed are IR, magnetic, and UV/Vis measurements.

Various catalysts for the polymerization of carbodiimide have been investigated. In early studies, anionic polymerization techniques were employed, but the products obtained were low molecular weight oligomers. More recently, a living route using titanium(IV) complexes as initiators has been employed and the high molecular weight polymers obtained exhibit a well-ordered helical, extendedchain conformation. However, the titanium complexes are sensitive to high temperatures and the presence of oxygen or water. Herein, we report that more robust catalysts based on copper(I) and copper(II) complexes also initiate living carbodiimide polymerizations. The tolerance of these complexes to impurities is illustrated by the fact that they cleanly initiate the polymerization of carbodiimides under air and oxygen. They are even active in the presence of water, but both molecular weights and yields tend to be lower than in dry solvents. It has been shown that the catalytic activity of a copper(II) amidinato complex is almost equal that of reported titanium(IV) initiators. Analysis of these systems by gel permeation chromatography-light scattering measurements (GPC-LS) and preliminary kinetic analysis suggest this system to be living.

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ABSTRACT:The polymerization of methyl methacrylate (MMA) by Cu(II) amidinate complexes in combination with alkyl aluminum complexes is reported. The preferred alkylating agent is methylaluminoxane (MAO) in terms of improved yield and catalyst activity. Mechanistic studies indicate that the active species is a copper(I) complex.KEY WORDS Poly(methyl methacrylate) / Copper Complex / Alkyl Aluminum Complex / Lewis Acid / Controlled Polymerization / A great challenge in the polymerization field has been the development of transition metal catalysts that are active toward the polymerization of polar and functional monomers. Themes have included ligands that are alternatives to the cyclopentadienyl 1 ligand and the use of later (e.g., Group VIII) transition metals as the base metals of the catalyst. 2