Synthetic and Structural Studies of Silver(I)‐ and Gold(I)‐ContainingN‐Heterocyclic Carbene Metallacrown Ethers
The ligands bis(imidazolium) hexafluorophosphate [RHimy-(CH2OCH2)n-HimyR][PF6]2 [Himy = –C3N2H3–, imidazolium; R = 1-naphthylmethyl, n = 2 (1a), 3 (2a); R = 9-anthracenylmethyl, n = 2 (1b), 3 (2b)] with a highly flexible polyether chain were easily prepared by the reaction of substituted imidazole with the corresponding polyglycol diiodide, followed by exchange of the anions with PF6–. Ligands 1a,b and 2a,b react with Ag2O to give monometallic AgI-containing N-heterocyclic carbene (NHC) metallacrown ethers 3a,b and 4a,b with a long and highly flexible bridging chain (CH2OCH2)n (n = 2, 3) between the two imidazolium units. Complexes 3a,b and 4a,b react with [Au(SMe2)Cl] in a transmetalation reaction to give AuI analogues 5a,b and 6a,b. Complexes 3a,b–6a,b are novel examples of a metallacrown ether with NHCs. In contrast to the use of a high-dilution technique in the preparation of polyether chain phosphane-containing metallacrown ethers, the new trans-metallacrown ethers can be prepared in concentrated solution. The structures of 3a–6a were confirmed by X-ray diffraction determination. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)