53432-08-9Relevant academic research and scientific papers
Preparation of organocobalt complexes through CF/CH bond activation of polyfluoroaryl imines
Lu, Faguan,Sun, Hongjian,Wang, Lin,Li, Xiaoyan
, p. 110 - 113 (2014/04/03)
In this paper, we reported the CF and CH bond activation of polyfluoroimine ligands induced by CoMe(PMe3)4. The reaction of pentafluorophenylmethylidene-2,6-diisopropylaniline 1 with CoMe(PMe 3)4 afforded an ortho-chelated cobalt(I) complex [Co(PMe3)3(C6F4-ortho-CH = N-C 6H3(iso-Pr)2(ortho, ortho))] (5) via CF bond activation and subsequent elimination of methyl fluoride. Under similar reaction conditions, the reactions of polyfluoroaryl imines 2-4 with CoMe(PMe 3)4 afforded the penta-coordinate cobalt(I) complexes 6-8 via CH bond activation and subsequent elimination of methane [Co(PMe 3)3(C6H2F 2(meta, meta)-ortho-(CH = N-C6H4Cl para)] (6), [Co(PMe3)3(C6H 2F2(meta, para)-ortho-(CH = N-C6H 4Clpara)] (7), and [Co(PMe3)3(C 6HF3(meta, meta, para)-ortho-(CH = N-C6H 4Clpara)] (8). Complexes 5-8 were characterized through IR, 1H NMR, 31P NMR, 19F NMR and elemental analyses. The crystal and molecular structures of complexes 5, 6 and 8 were determined by X-ray single crystal diffraction. The reactions of 8 with MeI and EtBr afforded organic fluorides 9-10. A proposed formation mechanism of 9-10 with the oxidative addition of RX at the cobalt(I) center of 8 and reductive elimination via C,C-coupling was discussed.
Intermolecular methyl group exchange and reversible P-Me bond cleavage at cobalt(III) dimethyl halide species
Xu, Hongwei,Williard, Paul G.,Bernskoetter, Wesley H.
, p. 798 - 806 (2013/03/28)
The cobalt(III) dimethyl halide complexes cis,mer-(PMe3) 3Co(CH3)2X (X = Cl, I) were found to undergo a degenerate cobalt-to-cobalt transfer of the methyl ligands during isotopic labeling experiments. Extensive mechanistic studies exclude radical, methyl iodide elimination, and disproportionation/comproportionation pathways for exchange of the methyl groups between metals. A related cobalt(III) dimethyl complex supported by the tridentate phosphine ligand MeP(CH2CH 2PMe2)2 showed dramatically slower methyl ligand transfer, indicative of a mechanism for intermetallic exchange with a requisite phosphine dissociation. Crossover experiments between cobalt(III) dimethyl halide complexes supported by PMe3 and MeP(CH 2CH2PMe2)2 are consistent with a dicobalt transition structure in which only one cobalt center requires phosphine dissociation prior to methyl transfer. An additional methyl group scrambling process between cis,mer-(PMe3)3Co(CH3) 2I and free PMe3 was also identified during the investigation and originates from reversible P-CH3 bond cleavage.
Oxidation-reduction exchange of 2-acylenolato and trimethylphosphane ligands between d6 and d8 complexes of nickel and cobalt
Klein, Hans-Friedrich,Li, Xiaoyan,Sun, Hongjian,Beck, Robert,Fl?rke, Ulrich,Haupt, Hans-Jürgen
, p. 63 - 69 (2008/10/08)
A series of five (C:O)-dianionic 1-acyl-2-enolato ligands C(O)-C=C-O in a transmetallation reaction between 18-electron metal-d6 complexes mer-trans-NiMe(X)[C(O)-C=C-O](PMe3)2 [C=C=C6H4, X = I (1); C=C=3-CMe3-5-Me-C6H2, X = I (2); C=C=5,6-benzo-C6H2, X = I (3); C=C=3,4-benzo-cyclohexene, X = Br (4); C=C=1,2-diphenylethene, X = I (5)] and the 18-electron metal-d8 compound CoMe(PMe3)4 (1:2), undergo a reductive coupling of acyl and methylnickel functions involving the C(O)-C=C-O ligands. Subsequent migration of methyl groups between cobalt intermediates generates three products: mer-trans-CoMe2[MeC(O)-C=C-O](PMe3)2 (6-10), Ni(PMe3)4, and CoX(PMe3)3. The X-ray crystal structure of compound 7 has been determined. The methyl ligands are found in positions opposite to the O-donor functions. Upon replacing the aromatic rings in salicylaldehyde derivatives C(O)-C=C-O by more flexible cyclohexene rings or acyclic systems the reduction of Ni(IV) complexes follows a different course. (C) 2000 Elsevier Science S.A.
