Synthesis And Catalysis Of Iron, Cobalt And Nickel Complexes

This thesis focuses on synthesis, characterization and catalysis of Li, Al, Zn, Fe, Co, Ni and Pd complexes bearing new types of N,N,O-, P,N,P-, P,N,N-, N,N,N-, P,N,O-chelate ligands.Chapter 1 describes synthesis and characterization of anionic N,N,O-ligands [{N(o-ROC₅H₄)C(SiMe₃)CH(2-C₅H₄N)}]^- ([L1]^-) and neutral ligands 2-{o-ROC₆H₄-NHC(SiMe₃)CH}C₅H₄N (1.7, R = PhCH₂; 1.8, R = ⁱPr) and their metal complexes including [Li{N(o-ROC₆H₄)C(SiMe₃)CH(2-C₅H₄N)}]2 (1.3, R = PhCH₂; 1.4, R = ⁱPr), [MX₂{(o-ROC₆H₄)N=C(SiMe₃)CH₂(2-C₅H₄N)}] (1.9, R = PhCH₂, M = Ni, X = Cl; 1.10, R =ⁱPr, M=Ni, X=Cl; 1.11, R = PhCH₂, M=Ni, X=Br; 1.12, R =ⁱPr, M = Ni, X = Br; 1.13, R = PhCH₂, M = Fe, X = Cl; 1.14, R = ⁱPr, M = Fe, X = Cl; 1.15, R = PhCH₂, M = Co, X = Cl; 1.16, R = ⁱPr, M = Co, X = Cl) and [MX₂{(o-MeC₆H₄)N=C-(SiMe₃)CH₂(2-C₅H₄N)}] (M = Ni, X = Br, 1.18; M = Co, X = Cl, 1.19). The structures of complexes 1.3, 1.6, 1.12 and 1.14 were characterized by single crystal X-ray diffraction techniques. The catalytic behavior in ethylene oligomerization of complexes 1.5,1.6,1.9-1.16,1.18 and 1.19 were investigated.Chapter 2 is on synthesis and characterization of nickel complexes bearing P,N,P-, P,N,N-, N,N,N- and P,N,O-amido pincer ligands including [(o-PPh₂C₆H₄)N-(PhC=CHPR₂)]NiX (2.1a R = Ph, X = Cl; 2.1b R = Prⁱ, X = Cl; 2.1c R = Prⁱ, X = Ph; 2.1d R = Prⁱ, X = Me; 2.1e R = Ph, X = Me; 2.1f R = Prⁱ, X = Buⁿ), [(o-PPh₂C₆H₄)N(PhC=CHPPr₂ⁱ=NAr)]NiX (2.2a Ar = o-MeCe₆H₄, X = Cl; 2.2b Ar = 2,6-ⁱPr₂C₆H₃, X = Cl; 2.2c Ar = o-MeC₆H₄, X = Me), [(o-PPh₂=NArC₆H₄)N-(PhC=CHPPr₂ⁱ)]NiCl (2.3a Ar = Ph, 2.3b Ar = o-MeC₆H₄, 2.3c Ar = 2,6-ⁱPr₂C₆H₃), [(o-PPh₂=NPhC₆H₄)N(PhC=CH- PPr₂ⁱ=NPh)]NiX (2.4a X = Cl, 2.4b X = Buⁿ), [(o-PPh₂C₆H₄)N(PhC=CHPR,R₂=O)]NiCl (2.27a R₁= R₂= Ph; 2.27b R₁= Et, R₂ = Ph). The structures of complexes 2.1c, 2.2b, 2.3c and 2.4b were determined by single crystal X-ray diffraction techniques.Chapter 3 deals with catalysis of amido pincer nickel complexes toward the Kumada cross-coupling reaction. The catalytic activity of complexes 2.1a-2.4b and other two kinds of amido pincer nickel complexes in the Kumada cross-coupling reaction was tested. From the test results, we found that the amido pincer complexes of nickel are highly active catalysts in cross-coupling of aryl Grignard reagents and aryl halides. Among the catalysts tested, the P,N,P-chelate nickel complexes showed relatively low catalytic activity compared with those bearing N,N,P- and N,N,N-chelate ligands. Excessive steric hindrance of ligands led to the decline of catalytic activity of the complexes in most cases. The reactions probably proceed through the single electron transfer processes from Grignard reagents to aryl halides at the initial stage of the reactions.Chapter 4 presents catalysis of complexes 2.1a-2.4a in the Negishi cross-coupling reaction. We found that these amido pincer complexes of nickel are highly active catalysts for the Negishi cross-coupling reaction. From the test results, we found that complexes 2.1a and 2.3c exhibit relatively low catalytic activity, while complexes 2.3b and 2.4a show the highest activity. The catalysts are effective for the reactions of unactivated aryl chlorides and heteroaryl chloride with aryl and heteroaryl zinc reagents. An extremely small amount of catalyst is required in most cases and the reaction displays good functional group tolerance.