Silver and Rhodium Complexes of Stable, Monomeric Imidazolidin‐2‐ylidenes: Synthesis, Reactivity and Decomposition Pathway

Abstract

Silver(I) complexes of the freely stable carbenes 1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene (3) and 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene (4) were prepared from the imidazolinium chlorides 1 and 2, respectively, and silver oxide. These two air-stable and light-sensitive carbene complexes [AgCl(3)] (5) and [AgCl(4)] (6) were characterized by NMR spectroscopy, and the molecular structure of 6 was confirmed by X-ray diffraction. The imidazolidin-2-thiones 7 and 8 were obtained by reaction of the silver carbene complexes 5 and 6, respectively, with elemental sulfur at ambient

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

“…The preparation of silver NHC complexes using the Ag 2 O method and the transfer of the NHC ligand to other transition metals has become a standard procedure in spite of a few reported cases where the method failed. [87] The Ag 2 O method often gives access to NHC complexes where alternative syntheses are tedious or unsuccessful.…”

The key role of R–NHC coupling (R = C, H, heteroatom) and M–NHC bond cleavage in the evolution of M/NHC complexes and formation of catalytically active species

“…Similar reactions of Cu I /NHC and Ag I /NHC complexes with sulfur afford azoline-2-thions. 186 – 188 , 207 The mechanisms of these reactions remain unexplored.…”

Heterocyclische Carbene – Synthese und Koordinationschemie

“…Das Azoliumsalz wird in der Regel an C 2 deprotoniert, und weitere azide Protonen im Azoliumsalz reagieren normalerweise nicht. Trotz einiger Berichte über erfolglose Carbentransfers87 ist die Synthese von Silber‐NHC‐Komplexen nach der Ag 2 O‐Methode mit anschließendem Transfer des Carbenliganden auf weitere Übergangsmetalle mittlerweile zu einer Routineprozedur geworden, die auch ansonsten nicht oder nur schwer zugängliche Carbenkomplexe liefert.…”