A triarylated 1,2,3-triazol-5-ylidene ligand with a redox-active ferrocenyl substituent for rhodium(I)-catalyzed hydroformylation of 1-octene

A series of rhodium(I)–1,2,3-triazol-5-ylidene (trz) complexes are described, containing either a novel triarylated trz ligand A′ (N1, N3-arylated, C4-ferrocenyl) {complexes 1, [Rh(A′)Cl(cod)]; 4, [Rh(A′)Cl(CO)2]}, or N3-alkylated triazolylidenes with a C4-ferrocenyl {2, [Rh(B′)Cl(cod)]; 5, [Rh(B′)Cl(CO)2]} or C4-phenyl substituent {3, [Rh(C′)Cl(cod)]; 6, [Rh(C′)Cl(CO)2]}. The free mesoionic carbene (MIC) A′ is structurally characterized and its electronic properties evaluated by employing the complex [Pd(Br)2(iPr2-bimy)(A′)] (7) in an NMR spectroscopic analysis method. The redox activity of A′ is exploited, and the chemically oxidized precursor Aox and complex 4ox are isolated. The mesoionic carbene complexes 1– 3, as well as in situ oxidized 1ox, are used as homogeneous catalysts for the hydroformylation of 1-octene for the first time, and the influence of chemical oxidation of the catalyst on the activity and chemo- and regioselectivity of the catalyst precursor 1 is evaluated.F.D. and T.W. gratefully acknowledge financial support from the Fonds der Chemischen Industrie (FCI). G.S.S. gratefully acknowledges financial support from the University of Cape Town and the NRF-DST Centre of Excellence in Catalysis (C*Change). D.I.B. and D.A. gratefully acknowledge the National Research Foundation, South Africa (NRF 87890, 97202 and 104205), and Sasol Technology R&D Pty. Ltd., South Africa for financial support.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-0682c2018-03-31hb2017Chemistr

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

Abstract 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