Application Of Low Valent Cobalt Complexes Supported By Trimethylphosphine In C-H,C-F Bond Activation

Cobalt belongs toâ…§family of transition metals.Because of its fine coordination activity and relatively low price,it has been widely used in organic synthesis, industrial catalysis,etc.Trivalent phosphine as a strong ligand can form stable complexes with transition metals,and can be widely found in organometallic compounds.Organocobalt compund supported by trimethylphosphine has high reaction activity and selectivity.A variety of C-H and C-F bond activation reactions are shown significant advantages in low valent transition metals complexes at present research.In this master's dissertation,application of cobalt complexes supported by trimethyphosphine in C-H and C-F bond activation are studied.The mail contents are described as follows:Reaction of cobalt complexes with alkyne compoundsActivation of C-H bond is always one of the most attractive field of organometallic study,and it is usually a key step in many catalytic processes.It has been reported that trimethylphosphine supported organocobalt compound can activate C-H bond.Alkyne complexes,especially its terminal hydrogen,is not only presence weak acidity but also has reaction activation.Reaction of multi-type alkyne complexes with CoL4Me(L=PMe₃) afforded novel organocobalt compounds by C-H bond activation in this dissertation.Reaction of alkynes with CoL₄Me afforded cobalt(I) compounds(18-19);In the reaction with(9-Anthracenyl)ethene afforded cobalt compound 20 which the hydrogen of neighbour benzene is actived.Application of low valent cobalt complexes in C-F bond activationC-F bond as one of the strongest chemical bond in organic chemistry is a challenge research field for its high bond energy and inertia.We have recently reported the reaction of CoL₄Me with ortho-fluorinated substrates containing imine anchoring groups afforded the[C-Co-F]fragment of organocobalt complexes supported by trimethylphosphine.Reaction of CoLaMe and CoLa with fluorinated substrates are selected to study and the novel C-F bond active complexes are expected to be afforded.Reaction of CoLa with 2,6-difluorindiphenylformaldehyde,a C=O bondÏ€-coordinate complex 21 was obtained.Reaction of electron-rich CoLaMe with 2,6-difluorindiphenylformaldehyde afforded the[C-Co-F]fragment of organocobalt complexes 22 expected.And CoLa react with 2,6-difluorindiphenylmethylamine also achieve C-F bond active complex 23.Reaction of acyl(hydrido) cobalt(â…¢) complexes with conjugated dialkyneTransition metal hydrido compounds play a central role in coordination catalysis, especially in the field of alkene and alkyne oligomerization and polymerization and organic synthesis.Particular attention has always been paid to these metal-hydrides in academe and industry.The research of reactive characters of M-H bond has been focused on for a long time.Compare with noble metals,nickel hydrides and cobalt hydrides show their attraction owing to the low price and environment friendly. Reaction of alkyne with cobalt hydrides complexes in normal temperature are afforded vinyl dinuclear cobalt(â…¢) compounds.Through the insertion reactions of acyl(hydrido)cobalt(â…¢) complexes(1-6) with alkynes,we try to synthesis and research the novel dinuclear or trinuclear conjugated cobalt(â…¢) complexes(7-14).All of the new complexes are characterized by IR,¹H,¹³C and ³¹P NMR.Structures of some single crystals have been confirmed by X-ray diffraction techniques.