Synthesis and Structural Characterization of N-Heterocyclic Carbene Complexes of Silver(I) and Rhodium(I) from Caffeine
Organometallics2004Vol. 23(8), pp. 1928–1931
Citations Over TimeTop 10% of 2004 papers
Abstract
The imidazolium cation 1,3,7,9-tetramethylxanthinium methyl sulfate (1a) is obtained by the reaction of caffeine with dimethyl sulfate. The anion exchange of 1a gives 1,3,7,9-tetramethylxanthinium hexafluorophosphate (1b). Ligand 1a reacts with Ag2O in water to yield an N-heterocyclic carbene (NHC) silver(I) complex (2a). Similarly, ligand 1b reacts with Ag2O in DMSO to yield NHC silver(I) complex 2b in high yield. A carbene transfer reaction of 2b with [Rh(COD)Cl]2 gives NHC Rh(I) complex 3. All compounds were characterized by 1H NMR, 13C NMR, and mass spectrometry. The solid-state structures of 1b, 2b, and 3 were determined by X-ray crystallography.
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