Synthesis and Structural Characterization of Water-Soluble Gold(I) N‑Heterocyclic Carbene Complexes. An X‑ray Absorption Fine Structure Spectroscopy (XAFS) Study

Water-soluble gold(I) N-heterocyclic carbene complexes were synthesized and characterized using X-ray absorption spectroscopy (XAFS) in combination with traditional analytical techniques such as NMR, mass spectrometry, and UV–vis spectroscopy. XANES and EXAFS regions are sensitive to coordination number, ligand electronic structure, and distance around the metal center, providing information on the oxidation state and bonding structure of gold, which allows discrimination between mono- and bis-carbene species. Preliminary results showed that the catalysts are active in the hydration of terminal alkynes in aqueous media; in addition, they are highly recyclable.