Jump to main content
Jump to site search

Issue 40, 2012
Previous Article Next Article

Synthesis and catalytic application of palladium imidazol(in)ium-2-dithiocarboxylate complexes

Author affiliations

Abstract

The palladium(II) dimer, [Pd(C,N-C6H4CH2NMe2)Cl]2 reacts with two equivalents of the NHC·CS2 zwitterionic ligands [NHC = IPr (1,3-diisopropylimidazol-2-ylidene), ICy (1,3-dicyclohexylimidazol-2-ylidene), IMes (1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene), IDip (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), SIMes (1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene)] in the presence of NH4PF6, to yield the cationic products [Pd(C,N-C6H4CH2NMe2)(S2C·NHC)]+. In a similar fashion, the compounds [Pd(C,N-bzq)(S2C·NHC)]+ (bzq = benzo[h]quinolinyl, NHC = ICy, IMes, IDip) are obtained from the corresponding dimer [Pd(C,N-bzq)Cl]2. The bis(phosphine) compounds [Pd(S2C·NHC)(PPh3)2]2+ (NHC = ICy, IMes, IDip, SIMes) are obtained on treatment of [PdCl2(PPh3)2] with NHC·CS2 zwitterions in the presence of NH4PF6. The reaction of [PdCl2(dppf)] with IMes·CS2 and NH4PF6 provides the complex [Pd(S2C·IMes)(dppf)]2+. The complexes [Pd(S2C·NHC)(PPh3)2](PF6)2 (NHC = IMes, IDip) were active pre-catalysts (1 mol% loading) for the conversion of benzo[h]quinoline to 10-methoxybenzo[h]quinoline in the presence of PhI(OAc)2 and methanol. The intermediacy of [Pd(C,N-bzq)(S2C·NHC)]+ was supported by the high yield of 10-methoxybenzo[h]quinoline using [Pd(C,N-bzq)(S2C·IDip)]+ to promote the same reaction. Small amounts of 2,10-dimethoxybenzo[h]quinoline were also isolated from these reactions. Using [Pd(C,N-bzq)(S2C·IDip)]+ and N-chlorosuccinimide as the oxidant led to the formation of 10-chlorobenzo[h]quinoline in moderate yield from benzo[h]quinoline. The molecular structures of [Pd(S2C·IMes)(PPh3)2](PF6)2 and [Pd(S2C·IMes)(dppf)](PF6)2 were determined crystallographically.

Graphical abstract: Synthesis and catalytic application of palladium imidazol(in)ium-2-dithiocarboxylate complexes

Back to tab navigation

Supplementary files

Publication details

The article was received on 29 Jun 2012, accepted on 15 Aug 2012 and first published on 16 Aug 2012


Article type: Paper
DOI: 10.1039/C2DT31413D
Citation: Dalton Trans., 2012,41, 12386-12394
  •   Request permissions

    Synthesis and catalytic application of palladium imidazol(in)ium-2-dithiocarboxylate complexes

    M. J. D. Champion, R. Solanki, L. Delaude, A. J. P. White and J. D. E. T. Wilton-Ely, Dalton Trans., 2012, 41, 12386
    DOI: 10.1039/C2DT31413D

Search articles by author

Spotlight

Advertisements