Tunable Rh(I) Fischer carbene complexes for application in the hydroformylation of 1-octene

• Published in: Journal of organometallic chemistry 2020-08, Vol.920, p.121341, Article 121341
• Main Authors: Mashabane, Tshegofatso L., Ramollo, G. Kabelo, Kleinhans, George, De Doncker, Stephen, Siangwata, Shepherd, Fernandes, Manuel A., Lemmerer, Andreas, Smith, Gregory S., Bezuidenhout, Daniela I.
• Format: Article
• Language: English
• Subjects: Ferrocenylcarbene; Fischer carbene complexes; Heterometallic complexes; Hydroformylation; p-N,N-dimethylaniline; Ruthenocenyl
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2020.121341

The preparation of a series of rhodium(I) complexes coordinated by various electronically tuneable Fischer carbene (FC) ligands, is reported. The Rh(I) metal complexes’ electronic properties could readily be modulated by variation of a p-N,N-dimethylaniline moiety with a ruthenocenyl substituent, or alternatively, substituting the carbene O-heteroatom for an amino-group. The electronic properties of the complexes were evaluated, and it was determined from the Tolman electronic parameters that the donor-ability of the FC ligands are comparable to N-heterocyclic carbenes. Furthermore, the facile control of the electronic properties of the complexes was demonstrated by mild oxidation of a ferrocenyl aminocarbene rhodium(I) complex, yielding the corresponding ferrocenium rhodium(I) complex cation. Finally, the complexes were evaluated as catalyst precursors for the hydroformylation of 1-octene. RhI Fischer carbene complexes are evaluated in the hydroformylation of 1-octene, with tailoring of the catalyst performance allowed by the tuning of the electronic properties of the electron-donating Fischer carbene ligands. [Display omitted] •The manuscript describes the synthesis and spectroscopic and structural characterisation of new Fischer carbene complexes of rhodium(I), containing ferrocenyl, ruthenocenyl, or p-N,N-dimethylaniline substituents.•The catalytic performance of the rhodium(I) Fischer carbene complexes in the hydroformylation of 1-octene was evaluated.•Chemical oxidation of the ferrocenyl aminocarbene rhodium(I) complex was investigated as a possible redox-switchable catalyst.•Improved catalytic activity (turnover frequency) was observed for ruthenocenyl Fischer carbene complexes, while improved regioselectivity (linear aldehyde formation) was achieved by the dimethylaniline Fischer carbene complexes.