0000000000528069
AUTHOR
Thomas Schleis
Ni(II) and Pd(II) complexes of camphor-derived diazadiene ligands: steric bulk tuning and ethylene polymerization
Abstract Nickel(II) and palladium(II) centers were coordinated to a series of chiral 1,4-diazadiene ligands. The ligand backbones are camphor derivatives and the imine nitrogens are attached to independently varied 2- and 2,6-substituted aryl groups. Upon activation with methyl-aluminoxane, the dibromo nickel complexes polymerize ethylene and 1-hexene. The polymerization properties are dependent on the steric features of the aryl substituents on the imine nitrogens.
Ethylene polymerization catalysts based on nickel(II) 1,4-diazadiene complexes: the influence of the 1,4-diazadiene backbone substituents on structure and reactivity
Abstract Thermally sensitive dialkyl nickel complexes {DAD(H,H)}Ni(CH2SiMe3)2 and {DAD(Me,Me)}Ni(CH2SiMe3)2 [DAD(X,X)=2,6-iPr2C6H4–NC(X)–C(X)N–C6H4iPr2-2,6] were synthesized and were characterized by X-ray diffraction studies on single crystals. The substituents X on the backbone of the α-diimine ligand significantly influence the conformation of the 2,6-diisopropylphenyl substituents. This effect is thought to be of crucial importance for the polymerization of ethylene when {DAD(X,X)}NiBr2/MAO is used as catalyst. The influence of the catalyst structure, pressure, and temperature on the polymerization activity, molar mass, glass transition temperature, melting temperature and branching o…