1201914-89-7Relevant academic research and scientific papers
Steric effect on construction of extended architectures of Ni(II) complexes directed by intermolecular C-H···F and C-H···O interactions
Kwak,Eom,Lee,Koo,Jang,Lee,Shin,Lah,Kim,Kim,Kim
, p. 923 - 930 (2010)
Five new Ni(II) complexes with pyridine carboxamide ligands have been synthesized and the crystal structures of three of the complexes were determined. Strong distortion effects of 6-methyl substitution were observed in the complexes with 6-methyl-substituted pyridyl bpb ligands. The C-H···F and C-H···O hydrogen bond interactions build extended architectures in the crystals studied. This result suggests that the steric effect of 6-methyl substitution plays an important role in the distortion of the structure, and the 6-methyl substitution can facilitate hydrogen bond interactions between methyl hydrogen atoms and O(carbonyl) or F atoms. Twelve Ni(II) complexes, including seven complexes reported previously, show reversible redox behavior, implying that the reduced Ni(I) state of each complex is stable in the time scale of CV measurement. The steric effect of R1 substituent and the electronic effects of X1 and X2 groups were found to be the main factors contributing to the shift of the redox potential of the Ni(II) complexes
Steric and electronic effects of tetradentate nickel(II) and palladium(II) complexes toward the vinyl polymerization of norbornene
Lee, Dong-Hwan,Lee, Jung Hwan,Eom, Geun Hee,Koo, Hyo Geun,Kim, Cheal,Lee, Ik-Mo
scheme or table, p. 1884 - 1890 (2012/01/17)
A series of Ni(II) and Pd(II) complexes bearing N4-type tetradentate ligands [Ni(X1X2-6-Me2bpb) 1] and [Pd(X1X 2-6-Me2bpb) 2]; 6-Me2bpb = N,N'-(o-phenylene) bis(6-methylpyridine-2-carboxamidate) X1 = Cl H or CH3 X2 = NO2 Cl F H CH3 or OCH3) were designed synthesized and characterized to investigate electronic and steric effects of ligand on the norbornene polymerization catalysts. Using modified methylaluminoxanes as an activator the complexes exhibited high catalytic activities for the polymerization of norbornene and the nickel complexes exhibited better catalytic activity the palladium complexes. Ni complex 1a with NO2 group on the benzene ring showed the highest catalytic activity of 4.9 × 106 g of PNBEs/molNi h and molecular weight of 15.28 × 105 g/mol with PDI 100 °C) and tend to afford higher polymerization productivities than the ones having electron-donating groups. Amorphous polynorbornenes were obtained with good solubility in halogenated aromatic solvents. A vinyl addition mechanism has been proposed for the catalytic polymerization.
