https://kops.uni-konstanz.de/bitstream/handle/123456789/10014/2000_CoordChemRev_203_325_Mecking.pdf;sequence=1

Cationic nickel and palladium complexes with bidentate ligands for the CC linkage of olefins

The chemistry of binuclear palladium(II) and platinum(II) complexes

Among a large variety of fine-tuning parameters for homogeneous catalysts the net charge of transition-metal complexes appear to be an interesting factor that considerably affects activation of substrates and catalytic activity in general. The electrophilicity of coordinated alkenes in transition-metal complexes can be strongly enhanced by increasing the positive net charge, resulting in strong carbocationic properties. Theoretical and experimental studies have shown that the alkene in cationic complexes is kinetically and thermodynamically more activated towards nucleophilic addition than in neutral complexes. The concept of increasing the positive complex charge is thought to be useful for the development of new catalysts for reactions in which alkenes or other unsaturated substrates are involved.

Enhancing electrophilic alkene activation by increasing the positive net charge in transition-metal complexes and application in homogeneous catalysis

https://dspace.library.uu.nl/bitstream/handle/1874/6561/12149.pdf;sequence=2

Synthesis and structural studies of phenyl( iodo) - and methyl( phenyl) palladium( II) complexes of bidentate nitrogen donor ligands

The reactivity of metal olefin complexes with non-innocent ligands (NILs) was examined. Treatment of PtCl2(diene) with the deprotonated catechol or aminophenol ligands afforded the corresponding Pt(NIL)(diene) complexes. The Pt(tBAFPh)(COD), Pt(tBAFPh)(nbd), and Pt(O2C6H2tBu2)(COD) (H2tBAFPh = 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, H2O2C6H2tBu2 = 3,5-di-tert-butylcatechol) complexes were examined by cyclic voltammetry. Treatment of Pt(tBAFPh)(COD) or Pt(tBAFPh)(nbd) with AgPF6 afforded the imino-semiquinones [Pt(tBAFPh)(COD)]PF6 or [Pt(tBAFPh)(nbd)]PF6, respectively. The [Pt(tBAFPh)(COD)] complex was unreactive toward nucleophiles, whereas the oxidized derivative, [Pt(tBAFPh)(COD)]PF6, rapidly and stereospecifically added alkoxides at the carbon trans to the phenolate. The Pt(tBAFPh)(COD), [Pt(tBAFPh)(COD)]PF6, Pt(tBAFPh)(C8H12OMe), and [Cp2Co][Pt(tBAFPh)(C8H12OMe)] complexes were characterized crystallographically.

/pdf/redox-activation-of-alkene-ligands-in-platinum-complexes-1sraz8mu9c.pdf

Agatino Spadaro

Papers

Preparation and reactions of palladium(II) and platinum(II) dienyl complexes