Chiral nickel(II) and palladium(II) catalysts bearing strong electron‐withdrawing fluorine groups: synthesis, characterization and their application in catalytic polymerization for ethylene and styrene. (9th May 2014)

• Record Type: Journal Article
• Authors: Yuan, Jianchao; Zhao, Jie; Song, Fengying; Xu, Weibing; Mu, Yanqiong; Chen, Jingjing; Zhang, Zhenghua
• Is Part Of: Applied organometallic chemistry. Volume 28:Number 7(2014:Jul.)
• Page Start: 484
• Page End: 494
• Publication Date: 2014-05-09
• Subjects: Organometallic chemistry -- Periodicals; Organometallic compounds -- Periodicals; 547.05
• DOI: 10.1002/aoc.3152
• Languages: English
• ISSNs: 0268-2605

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A series of new chiral and achiral nickel(II) and palladium(II) complexes, {bis[<italic>N</italic>, <italic>N</italic>′‐(2, 6‐diethyl‐4‐naphthylphenyl)imino]‐1, 2‐dimethylethane}dibromonickel <bold>3a</bold>, {bis[<italic>N</italic>, <italic>N</italic>′‐(4‐fluoro‐2‐methyl‐6‐<italic>sec</italic>‐phenethylphenyl)imino]‐1, 2‐dimethylethane}dibromonickel <italic>rac</italic>‐(<italic>RS</italic>)‐<bold>3b</bold>, {bis[<italic>N</italic>, <italic>N</italic>′‐(4‐fluoro‐6‐<italic>sec</italic>‐phenethylphenyl)imino]‐1, 2‐dimethylethane}dibromonickel <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3c</bold> and {bis[<italic>N</italic>, <italic>N</italic>′‐(4‐fluoro‐6‐<italic>sec</italic>‐phenethylphenyl)imino]‐1, 2‐dimethylethane}dichloropalladium <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3d</bold> were successfully synthesized and characterized. The molecular structures of representative ligand <italic>rac</italic>‐(<italic>RS</italic>)‐<bold>2b</bold>, nickel complex <bold>3a</bold>, <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3c</bold> and palladium complex <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3d</bold> were determined by X‐ray crystallography. The structures of complexes <bold>3a</bold> and <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3c</bold> have pseudo‐tetrahedral geometry about the nickel center, showing <italic>C</italic><sub>2</sub> molecular symmetry. However, the structure of palladium complex <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3d</bold> has <italic>pseudo</italic>‐square planar geometry about the palladium center, showing <italic>C</italic><sub>2</sub> molecular symmetry. Complex <bold>3e</bold> {bis[<italic>N</italic>, <italic>N</italic>′‐(2, 6‐dimethylphenyl)imino]‐1, 2‐dimethylethane}dibromonickel was also synthesized for comparison. Nickel complex <italic>rac</italic>‐(<italic>RS</italic>)‐<bold>3b</bold> bearing strong electron‐withdrawing fluorine group in the <italic>para</italic>‐aryl position and a chiral <italic>sec</italic>‐phenethyl group in the <italic>ortho</italic>‐aryl position of the ligand (one methyl group in the <italic>ortho</italic>‐aryl position) displays the highest <named-content content-type="chemicalTechnology" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">catalytic activity</named-content> for ethylene and styrene <named-content content-type="reactionType" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">polymerization</named-content>, and produced highly branched polyethylene and syndiotactic‐rich polystyrene. However, palladium complex <italic>rac</italic>‐(<italic>RR/SS</italic>)‐<bold>3d</bold> shows low <named-content content-type="chemicalTechnology" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">catalytic activity</named-content> for ethylene and styrene <named-content content-type="reactionType" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">polymerization</named-content> due to the poor leaving group, Cl, attached to palladium and the unfavorable molecular structure. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>