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We present the mechanistic understanding of an electrochemically-driven nickel-catalyzed coupling reaction. Computational analysis reveals that the spin density is mostly residing on the nickel (Ni) center when NiII is reduced to NiI. Ni-mediated halogen atom abstraction through outer-sphere electron-transfer pathway to yield coupling products under mild conditions is demonstrated. Importantly, we have elucidated the role of NiI and Ni0 for successive coupling of benzyl bromide and benzyl chloride derivatives, respectively, to corresponding bibenzyl products. The Ni-catalyst bearing a PN3P-ligand is an effective catalyst, producing a strong ligand effect on the reactivity and selectivity for the homocoupling reactions.

In the presence of a small molecular protic initiator, immortal ring-opening polymerization (ROP) of lactide (LA) is a highly efficient strategy to synthesize polylactide in a controllable manner, while using polymeric alcohol as an initiator has been less investigated. A series of polymeric alcohols (PS–OH) composed of styrene and 4.3%–18% hydroxyl functional styrene (diethyl(hydroxy(4-vinylphenyl)methyl)phosphonate, St–OH) were synthesized through reversible addition-fragmentation transfer (RAFT) polymerization. Using PS–OH as an initiator, the immortal ROP of rac-LA was catalyzed by dibutylmagnesium (MgnBu2) under various ratios of monomer to hydroxyl group within PS–OH to generate polystyrene-g-polylactide (PS–g–PLA) copolymers with different graft lengths. After thermal annealing at 115 °C, the PLA domain aggregated to nanospheres among the PS continuum. The size of the nanospheres, varying from 130.1 to 224.2 nm, was related to the graft density and length of PS–g–PLA. Nanoporous films were afforded through chemical etching of the PLA component.

(E)-1-(4-Methylphenyl)-1,3-butadiene(E-1-MPBD) synthesized via the “Wittig-type” reactionwas polymerized with the ternary catalytic system (Flu-NHC)Lu(CH2SiMe3)2/AliBu3/[Ph3C][B(C6F5)4] (Flu-NHC = C13H8CH2CH2(NCHCHN(C6H2Me3-2,4,6)C)to afford a new product containing exclusively trans-3,4 (>99%) units with perfect syndiotacticity (rrrr> 99%). The regio-3,4 tacticity was proved by the IR and NMR(1H and 13C) spectroscopic analyses, while the3,4-stereotacticity was confirmed by a model polymer with lower regularity(3,4 = 90.9%, rrrr= 49.3%) prepared by the binarycatalytic system (Am-NHC)Lu(CH2SiMe3)2/[Ph3C][B(C6F5)4] (Am-NHC= 2,6-iPrC6H3NC(C6H5)NCH2CH2(NCHCHN(C6H2Me3-2,4,6)C). The trans-planar conformation was uncovered through 2D-NOESY and 13C CPMAS NMR technologies. This represents the first stereo 3,4-syndioselectivepolymerization of 1,3-dienes achieved by a rare-earth metal basedcatalyst. Moreover, hydrogenating the resulting polymer gave the highlysyndiotactic poly(4-methylphenyl-1-butene), which cannot be achievedby any other manner at the present stage. [ABSTRACT FROM AUTHOR]