doi:10.1021/acs.organomet.4c00409engEspañol-Sánchez, BelindaGaliana-Cameo, MaríaUrriolabeitia, AsierPolo, VictorPassarelli, VincenzoPérez-Torrente, Jesús J.Castarlenas, RicardoTuning the pyridone scaffold within a Rhodium-NHC platform for gem-specific alkyne dimerization via a ligand-assisted proton shuttle mechanismART-2024-140734A series of mononuclear square-planar Rh{κ2N,O-BHetA}(η2-coe)(NHC) (BHetA = Bis-Heteroatomic Acidato) complexes have been prepared. Modifications of the pyridonato BHetA-type ligand architecture include 4-Me, 5-Me, 6-Me, 3-Br, 4-Br, 4-OMe, and 5-NO2 substitutions as well as pyrimidonato, succinimidato, and 2-piperidonato catalysts. Two structural isomers have been observed for the complexes, depending on the stereoelectronic properties of the ligand. The structure–activity relationship has been studied for gem-specific alkyne dimerization via a cooperative ligand-assisted proton shuttle mechanism. Density functional theory calculations have revealed a mechanistic pathway involving the hemilabile coordination of the BHetA ligand, CMD deprotonation, π-alkyne protonation, and reductive elimination. The increase in oxygen basicity imparted by the substituent in the pyridonato ligand is key, the 4-methyl derivative being the most active catalyst. However, a favored iminol–amide tautomerization precludes an increase in catalytic activity for the more basic saturated piperidonato catalyst.2024http://zaguan.unizar.es/record/14704010.1021/acs.organomet.4c00409http://zaguan.unizar.es/record/147040oai:zaguan.unizar.es:147040info:eu-repo/grantAgreement/ES/DGA/E42-23Rinfo:eu-repo/grantAgreement/ES/MECD/FPU17-05417info:eu-repo/grantAgreement/ES/MICINN/PID2019-103965GB-I00/AEI/10.13039/501100011033info:eu-repo/grantAgreement/ES/MICINN/PID2022-137208NB-I00Organometallics 43, 22 (2024), 2951-2962by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/openAccess