Anionic N-heterocyclic carbenes featuring weakly coordinating perfluoroalkylphosphorane moieties

• Published in: Dalton transactions : an international journal of inorganic chemistry 2023-07, Vol.52 (28), p.9553-9561
• Main Authors: Zapf, Ludwig, Radius, Udo, Finze, Maik
• Format: Article
• Language: English
• Subjects: Anions; Carbenes; Gold; Imidazoline; Ligands; Phosphines; Quantum chemistry; Selenium
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt01249b

The anionic 1-methyl-3-(tris(pentafluoroethyl)difluorophosphorane)imidazoline-2-ylidenate 3 and the 1,3-bis(tris(pentafluoroethyl)difluorophosphorane)imidazoline-2-ylidenate dianion 4 were obtained in high yield by deprotonation of {(C 2 F 5 ) 3 PF 2 }-methylimidazole 1 and the {(C 2 F 5 ) 3 PF 2 } 2 -imidazolate anion 2 . Carbenes 3 and 4 are first examples for a novel class of NHCs carrying weakly coordinating anions (WCA-NHCs). First reactions of these new ligands with elemental selenium and chloro(phosphine)gold( i ) complexes to result in an anionic selenium adduct ( 5 ) and WCA-NHC gold complexes ( 6 and 7 ) have been undertaken. The structural and spectroscopic properties of these NHC derivatives in conjunction with data from quantum chemical calculations provide an insight into the electronic and steric properties of the WCA-NHCs 3 and 4 . Especially the combination of properties such as weakly coordinating periphery combined with the coordinative carbene center, negative charge, large buried volume (% V bur ), and strong σ-donor as well as efficient π-acceptor ability render NHCs 3 and 4 unique and promising new ligands. Novel anionic N-heterocyclic carbenes featuring weakly coordinating (C 2 F 5 ) 3 PF 2 − groups at imidazoline were synthesized. These WCA-NHCs are promising ligands with enhanced donor and acceptor properties compared to neutral NHCs.