Reaction of (NHC)­Au–X (X = halide) complexes with 2- or 4-mercaptopyridine under basic conditions allows for the preparation of a series of (NHC)­AuI–mercaptopyridine complexes 1–4 in high yields. All complexes have been fully characterized by means of 1H and 13C NMR spectroscopy, melting point, and elemental analysis. Single crystals of complexes 1–3 were obtained, and the solid-state structures display a linear Au­(I) center with coordination to the NHC ligand and the sulfur atom of the mercaptopyridine moiety. Interestingly, weak γ-anagostic C–H···Au interactions are found in complexes 1–3 regardless of the relative N or S position in the mercaptopyridine. Taking advantage of the free pyridine nitrogen, reaction of complexes 1 and 2 with palladium allyl chloride dimer permits the isolation of heteronuclear Au/Pd complexes 5 and 8 featuring a bridging ambidentate mercaptopyridine ligand. Further reactivity of complexes 1–3 toward B­(C6F5)3 produces complexes 6, 7, and 9, which display frustrated Lewis pair reactivity with the activation of a H–F bond.

Treatment of NHC–AuCl (NHC = IPr and IMes) complexes with equimolar amounts of KTpR2 (R = Me, H) salts in tetrahydrofuran produces in high yields the heteroleptic complexes 3–6 with the general formula NHC–Au–TpR2.

We report the synthesis and full characterization of a novel series of indole‐derived triazolium salts and their corresponding triazolylidene gold, palladium, rhodium, and iridium complexes. All new compounds were fully characterized by means of 1H and 13C NMR spectroscopy, elemental analyses, and in the case of triazoliums 1 and 2 and complexes 3, 4, and 9, by single crystal X‐ray diffraction. Gold complexes demonstrated a good catalytic performance in the hydrohydrazination of terminal alkynes producing a series of substituted hydrazones in good yields under mild reaction conditions. Additionally, the iridium complex (9) performed well in the catalytic transfer hydrogenation of ketones and aldehydes using isopropanol as hydrogen source.

Blue-LED light or direct sunlight induces cyclization in tryptamine-quinone hybrid compounds. Formation of a C-C bond between the C-2 atom of the indole and the bromo-naphthoquinone takes place in chloroform solution in air without the need for a photocatalyst. The reaction allows the presence of a bromine atom on the indole ring which can be used for subsequent cross coupling reactions. On the other hand, the bromine atom on the naphthoquinone is strictly necessary for the cyclization to occur. The cyclic products of these reactions are blue pigments with broad absorption in the visible region.