Syntheses And Catalytic Properties Of Half-sandwich Ruthenium(Ⅱ) Complexes With Chiral Schiff-Base Ligands

With their unique structures and chemical properties,half-sandwich ruthenium complexes have attracted great interest of researchers and they have been widely applied in the fields of chemical catalysis,self-assembly of supramolecular architectures,host-guest chemistry and biological anticancer activity.Synthetic reactions,structural characterization and catalytic properties were well investigated in this thesis.A series of chiral Schiff base ligands HL1*-HL8*were synthesized by condensation reactions of salicylaldehyde,5-chlorosalicylaldehyde,3,5-dibromosalicylaldehyde and 3,5-di-tert-butylsalicylaldehyde with various chiral amines.The ligands HL1*-HL8*were characterized by UV-Vis,FT-IR and ¹H NMR spectroscopies and elemental analyses.The structures of（R）-N-（1-phenylethyl）-salicylidene（HL1*）,（R）-N-（1-hydroxyethylphenyl）-5-chlorosalicylidene（HL4*）,（S）-N-（1hydroxyethylethyl）-3,5-dibromosalicylidene（HL5*）and（R）-N-（1-phenylethyl）-3,5-di-tert-butylsalicylidene（HL7*）have been unambiguously established by single-crystal X-ray crystallography.Four choloro-bridged ruthenium complexes containing different aryl groups[（η⁶-p-cymene）RuCl₂]₂,[（η⁶-C₆H₆）RuCl₂]₂,[Ru（COD）Cl₂]_n（COD=1,5-cyclooctadiene）and[RuCl₂Cp*]₂（Cp*=1,2,3,4,5-pentamethylcyclopentadiene）were prepared from industrial RuCl₃?3H₂O by the methods reported in references.Treatment of[（η⁶-p-cymene）RuCl₂]₂ with two equiv.of HL1*and HL7*in THF in the presences of Et₃N and Ag NO₃ afforded complexes（R）-[（η⁶-p-cymene）Ru（κ²-N,O-L1*）Cl]（1）and（R）-[（η⁶-p-cymene）Ru（κ²-N,O-L7*）Cl]（2）,respectively.Similarly,reactions of[（η⁶-C₆H₆）RuCl₂]₂ with two equiv.of HL5*and HL6*in CH₃OH gave complexes（S）-[（η⁶-C₆H₆）Ru（κ²-N,O-L5*）Cl]（3）and（R）-[（η⁶-C₆H₆）Ru（κ²-N,O-L6*）Cl]（4）,respectively.Interaction of[Ru（COD）Cl₂]_n with two equiv.of HL2*and HL3*in THF/DMF at reflux overnight resulted in isolation of the two complexes（R）-[（COD）Ru（κ²-N,O-L2*）Cl]（5）and（R）-[（COD）Ru（κ²-N,O-L3*）Cl]（6）,respectively.Treatment of[RuCl₂Cp*]₂ with two equiv.of HL4*and HL8*in CH₂Cl₂/CH₃OH（v/v=4:1）afforded complexes（R）-[（Cp*）Ru（κ²-N,O-L4*）Cl]（7）and（R）-[（Cp*）Ru（κ²-N,O-L8*）Cl]（8）,respectively.Additionally,we isolated an unexpected dinuclear ruthenium complex[（COD）RuCl（μ-Cl）₃Ru（COD）DMF]（6’）.Expect for the complexes 7 and 8which exhibited paramagnetic behaviors,complexes 1-6 were characterized by ¹H NMR spectroscopy.All the half-sandwich ruthenium complexes with chiral Schiff base ligands were characterized by UV-Vis and FT-IR spectroscopies along with elemental analyses.Moreover,molecular structures of complex 2 and 6’have been established by single-crystal X-ray crystallography.The electronic and photocatalytic properties for hydrogen production by water splitting of complex 2 under visible light（λ>420 nm）were also investigated.Moreover,the potential use of complex 2 in the asymmetric cyclopropanation of styrene was also explored in this thesis.