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Silver, Gold, Palladium, and Platinum N‑heterocyclic Carbene Complexes Containing a Selenoether-Functionalized Imidazol-2-ylidene Moiety

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journal contribution
posted on 2018-01-17, 15:54 authored by Karsten Klauke, Irina Gruber, Tim-Oliver Knedel, Laura Schmolke, Juri Barthel, Hergen Breitzke, Gerd Buntkowsky, Christoph Janiak
The selenoether-functionalized imidazolium salt N-[(phenylseleno)­methylene)]-N′-methylimidazolium chloride (LH+Cl) was transformed into the metal–carbene complexes [AgCl­(L)], [AuCl­(L)], [PdCl2(L)], and [PtCl2(L)] by the reaction with Ag2O and an additional transmetalation reaction of [AgCl­(L)] with [(THT)­AuCl], [(COD)­PdCl2], and [(COD)­PtCl2], respectively (THT = tetrahydrothiophene, COD = cyclooctadiene). The compound [AuI2Cl­(L)] was prepared by oxidation of [AuCl­(L)] with elemental iodine. The microwave-assisted decomposition of [PdCl2(L)] in the ionic liquid 1-butyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([BMIm]­NTf2) or in propylene carbonate led to the formation of Pd17Se15 nanoparticles of 51 ± 17 or 26 ± 7 nm diameter, respectively. The decomposition of the platinum complex resulted in either small Pt clusters around 1 nm size from the ionic liquid suspension or Pt nanoparticles of 3 ± 1 nm diameter in propylene carbonate. High-resolution X-ray photoelectron spectroscopy (HR-XPS) and 13C cross-polarization magic-angle spinning (CP MAS) NMR indicated that the surface of Pt clusters and crystalline Pt nanoparticles is formed by an amorphous Pt­(II)/Se shell and by carbene ligand residues.