Abstract:
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.
