Design, synthesis and characterization of water soluble heterobimetallic complexes and their evaluation as aqueous biphasic hydroformylation catalysts

Includes bibliographical referencesA series of new water-soluble N,O-chelating Schiff base ligands were synthesised. These ligands were reacted with ferrocenecarboxaldehyde through Schiff base condensation reactions, leading to new water-soluble ferrocenylimine mononuclear complexes. The mononuclear complexes were reacted with a dimeric rhodium precursor [RhCl(COD)]2 to produce a series of novel ferrocenylimine-Rh(I) heterobimetallic complexes. Both themononuclear and heterobimetallic complexes were found to have good solubility in water of up to 11 mg/mL. The complexes were characterised fully using various spectroscopic and analytical techniques including 1H NMR, 13C NMR spectroscopy, FT-IR spectroscopy, mass spectrometry and elemental analysis. In addition, mononuclear and heterobimetallic complexes were also synthesised as precursors to dendritic DAB-G1 structures. These were found to be water-soluble and they were also characterised using spectroscopic and analytical techniques. The two monometallic and two heterobimetallic complexes were evaluated as pre-catalysts for the aqueous biphasic hydro formylation of 1-octene.The mononuclear ferrocenyl complexes were inactive in the aqueous biphasic hydroformylation experiments. Hydroformylation using the heterobimetallic complexes showed that the pre-catalysts are active in 1-octene conversion, yielding aldehydes (linear and branched) as well as isomerisation products (cis and trans 2- and 3-octene). Linear aldehydes were more favoured with the tertiary-butyl analogue of the heterobimetallic complex. Although loss of metal from the aqueous layer was detected using ICP-OES, the catalysts exhibited good recyclability and could be reused up to 4 times

Room Temperature Hydrogenation of CO2 Utilizing a Cooperative Phosphorus Pyridone‐Based Iridium Complex

The synthesis, characterization and application of a new complex, [Ir(κ2-P,N-6-DCyPon*)(COD)] (1), where 6-DCyPon* is the anionic species, 6-dicyclohexylphosphino-2-oxo-pyridinide, is reported herein. Complex 1 was found to be an active catalyst in the hydrogenation of CO2 at room temperature. The ligand, 6-DCyPon*, is derived via deprotonation of a novel pro-ligand, 6-DCyPon (6-dicyclohexylphosphino-2-pyridone) during the synthesis of 1. The ligand is shown to participate within the reversible hydrogenation of 1, via a cooperative process, in which the species, [IrH3(κ2-P,N-6-DCyPon)(COD)] (2), was spectroscopically characterized, where 1 reacts with two equivalents of H2

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