New Functionalized Vinyl Monomers by Ethylene‐(Functionalized)‐Norbornene Hetero‐Trimerization Catalyzed by Cobalt(II)‐(Imino)pyridine Complexes

Abstract

On activation by MAO the (imino)pyridine cobalt(II) complex CoCl 2 N 2 Ph/i-Pr 2 catalyzes the enchainment of one norbornene (NB) molecule with two ethylene molecules to give exo-2,exo-3-ethylvinylnorbornane with high activity and complete diastereoselectivity. Turnover frequencies [TOF, mol NB (mol Co h) À1] as high as 270,000 have been obtained. The 2E-1NB hetero-trimerization reaction has been also accomplished with NBs bearing polar substituents such as norbornenemethanol and norbornenecarboxylic acid provided that the substrate is protected with triisobutylaluminum and the less sterically demanding complex CoCl 2 N 2 Ph/Me 2 is used as catalyst precursor. A mechanism for the hetero-trimerization reactions is proposed on the basis of experimental evidence.

Olefin oligomerization, homopolymerization and copolymerization by late transition metals supported by (imino)pyridine ligands

“…For cobalt systems, the dihalide precursors are expected to follow a "traditional" activation pathway, leading to a cationic alkyl propagating species [3,8,52].…”

“…Conversely, 6-phenyl or 6-naphthyl-containing ligands can be conveniently synthesized by a Suzuki coupling [34,35]. The reaction between 6-bromo-2-acetylpyridine and either phenyl-or naphthyl-boronic acid, followed by the aniline condensation affords the (imino)pyridine ligands in good yield (Scheme 3b) [3][4][5][6]8].…”

“…Stille coupling [33,34] has been used for preparing 6-heteroaryl-2-iminopyridyl ligands under mild conditions from good to high yields. In general, 2-bromo-6-iminopyridyl systems are reacted with a slight excess of the heteroaryl stannane (Scheme 3a) [3][4][5][6][7][8]. Conversely, 6-phenyl or 6-naphthyl-containing ligands can be conveniently synthesized by a Suzuki coupling [34,35].…”

“…Indeed, several (imino)pyridine Co II complexes exhibit unrivalled activity for the oligomerization of ethylene to short-chain ␣-olefins (C 4 -C 12 ) [3][4][5][6][7][8].…”

Synthesis and characterization of some water soluble Zn(ii) complexes with (E)-N-(pyridin-2-ylmethylene)arylamines that regulate tumour cell death by interacting with DNA

“…1 Apart from possible structural disparity of the metal complexes of such tridentate 2,6-bis(arylimino)pyridyl ligands, bidentate iminopyridyl based ligands were also investigated with first and second row late transition metal (Fe, Co, Ni, Cu, Zn and Pd) halides and some of them have shown exceptional catalytic activities. [2][3][4][5][6][7] These metal catalyst precursors can be prepared by addition of ligands to either anhydrous or hydrated dihalides in a suitable solvent. Complexes can be isolated as mononuclear species or, depending on both the metal halides and the degree of substitution of the pyridine ring, as centrosymmetric dinuclear molecules.…”