Preparation of multiblock copolymers via step-wise addition of l-lactide and trimethylene carbonate.

Poly(l-lactide) (PLA) is a bioderived and biodegradable polymer that has limited applications due to its hard and brittle nature. Incorporation of 1,3-trimethylene carbonate into PLA, in a block copolymer fashion, improves the mechanical properties, while retaining the biodegradability of the polymer, and broadens its range of applications. However, the preparation of 1,3-trimethylene carbonate (TMC)/l-lactide (LA) copolymers beyond diblock and triblock structures has not been reported, with explanations focusing mostly on thermodynamic reasons that impede the copolymerization of TMC after lactide. We discuss the preparation of multiblock copolymers via the ring opening polymerization (ROP) of LA and TMC, in a step-wise addition, by a ferrocene-chelating heteroscorpionate zinc complex, {[fc(PPh2)(BH[(3,5-Me)2pz]2)]Zn(μ-OCH2Ph)}2 ([(fcP,B)Zn(μ-OCH2Ph)]2, fc = 1,1'-ferrocenediyl, pz = pyrazole). The synthesis of up to pentablock copolymers, from various combinations of LA and TMC, was accomplished and the physical, thermal, and mechanical properties of the resulting copolymers evaluated

Symmetrically and Non-symmetrically Substituted 1,1’-ferrocenes as Supporting Ligands for Divalent Metals in Catalysis

The synthesis of new polymers is motivated by the limitations of current materials. Recently, interest in copolymers containing blocks that display different or complementary properties has been increasing since these materials have potential for further performance enhancements. Inspired by recent developments in olefin polymerization catalysts, and based on the interest of the Diaconescu group in the reactivity of complexes supported by ferrocene-based chelating ligands, we developed a new ferrocene-chelating heteroscorpionate supporting ligand and investigated its applications in combination with late transition metals to redox-switchable catalysis for the production of multiblock copolymers. Additionally, we began investigations into the influence of the iron-secondary metal interactions on redox-switchable catalysis in complexes supported by symmetrically substituted, neutral ferrocene-based ligands

Synthesis and characterization of ferrocene-chelating heteroscorpionate complexes of nickel(II) and zinc(II).

The first example of a ferrocene-chelating heteroscorpionate, [Li(THF)2][fc(PPh2)(BH[(3,5-Me)2pz]2)] ((fc(P,B))Li(THF)2, fc = 1,1'-ferrocenediyl) is described. Starting from a previously reported compound, fcBr(PPh2), a series of ferrocene derivatives, fc(PPh2)(B[OMe]2), [Li(OEt2)][fc(PPh2)(BH3)], [Li(THF)2][fc(PPh2)(BH[(3,5-Me)2pz]2)] (pz = pyrazole), was isolated and characterized. Compound (fc(P,B))Li(THF)2 allowed the synthesis of the corresponding nickel and zinc complexes, (fc(P,B))NiCl, (fc(P,B))NiMe, (fc(P,B))ZnCl, and (fc(P,B))ZnMe. All compounds were characterized by NMR spectroscopy, while the zinc and nickel complexes were also characterized by X-ray crystallography. The redox behavior of (fc(P,B))NiCl, (fc(P,B))NiMe, (fc(P,B))ZnCl, and (fc(P,B))ZnMe was studied by cyclic voltammetry and supported by density functional theory calculations

Synthesis and Characterization of Ferrocene-Chelating Heteroscorpionate Complexes of Nickel(II) and Zinc(II)

The first example of a ferrocene-chelating heteroscorpionate, [Li­(THF)₂]­[fc­(PPh₂)­(BH­[(3,5-Me)₂pz]₂)] ((fc^P,B)­Li­(THF)₂, fc = 1,1′-ferrocenediyl) is described. Starting from a previously reported compound, fcBr­(PPh₂), a series of ferrocene derivatives, fc­(PPh₂)­(B­[OMe]₂), [Li­(OEt₂)]­[fc­(PPh₂)­(BH₃)], [Li­(THF)₂]­[fc­(PPh₂)­(BH­[(3,5-Me)₂pz]₂)] (pz = pyrazole), was isolated and characterized. Compound (fc^P,B)­Li­(THF)₂ allowed the synthesis of the corresponding nickel and zinc complexes, (fc^P,B)­NiCl, (fc^P,B)­NiMe, (fc^P,B)­ZnCl, and (fc^P,B)­ZnMe. All compounds were characterized by NMR spectroscopy, while the zinc and nickel complexes were also characterized by X-ray crystallography. The redox behavior of (fc^P,B)­NiCl, (fc^P,B)­NiMe, (fc^P,B)­ZnCl, and (fc^P,B)­ZnMe was studied by cyclic voltammetry and supported by density functional theory calculations

Ferrocene-bis(phosphinimine) Nickel(II) and Palladium(II) Alkyl Complexes: Influence of the Fe–M (M = Ni and Pd) Interaction on Redox Activity and Olefin Coordination

The synthesis of several novel nickel­(II) and palladium­(II) ferrocene-bis­(phosphinimine) alkyl complexes containing iron–nickel and iron–palladium interactions is reported. The redox behavior of all complexes was evaluated electrochemically and chemically; in addition, reactions with weak nucleophiles, such as acetonitrile and olefins, were also investigated. DFT calculations were performed to understand the electronic structure of the alkyl metal complexes