Syntheses And Characterization Of Bis(N-Heterocyclic Carbene)borate Metal Complexes

N-Heterocyclic carbenes（NHCs）have been widely used in coordination chemistry and homogeneous catalysis since they can form stable metal-NHC bonds（NHCs）with metal center due to their strong σ-donor capacity.Recently,bis（imidazol-2-ylidene）borate ligand has attracted increasing attention due to their unique properties.Considerable number of metal complexes with bis（imidazol-2-ylidene）borate ligands have been reported and the properties of their complexes have been considerably studied.It is surprising that no iron,cobalt,complex with bis（N-heterocyclic carbene）borate ligands have been reported yet.The research presented in this thesis focused on the synthesis,characterization and reactivities of iron,cobalt,palladium complexes of bis（N-heterocyclic carbenes）borate.The substitution reaction of bis（N-heterocyclic carbene）borate rhodium（Ⅰ）and iridium（Ⅰ）complexes with isocyanide have been also studied.This thesis contains the following three sections:1.Four-coordinate Co（Ⅱ）and Fe（H）complexes with bis（N-heterocyclic carbene）borate and their magnetic propertiesThe carbene complexes（Bcteu）₂Co and（BCR）2Fe（R =tBu,neopentyl）with bis（3-tert-butylimidazol-2-ylidene）borate ligand have been synthesized.These complexes were characterized by single-crystal X-ray diffraction,suggesting that coordination geometry of lsp is square planar configuration while coordination geometry of 1_Td,2,and 3 is tetrahedral configuration.Their magnetic properties were studied by SQUID.The equilibrium of planar（S=1/2）（?）tetrahedral（S=3/2）in solution was studied by Evans method for comlexes 1sp（square planar）and 1_Td（tetrahedral）.2.Synthesis and characterization of rhodium（I）and iridium（I）carbonyl isocyanide complexes with bis（N-heterocyclic carbene）borate ligandsComplexes(Bc^tBu)Rh（CO）₂,(F₂Bc^tBu)Rh（CO）₂,(Bc^tBu)Ir（CO）2 reacted with CN-R（R =2,6-Me₂C₆H₃NC,tBu）to yield the six products containing isocyanide[(Bc^tBu)Rh（CO）（tBuNC）]（4）,[(F₂Bc^tBu)Rh（CO）（tBuNC）]（5）,[(Bc^tBu)Rh（CO）（2,6-Me₂C₆H₃NC）]（6）,[(F₂Bc^tBu)Rh（CO）（2,6-Me₂C₆H₃NC）]（7）,[(F₂Bc^tBu)Ir（CO）（tBuNC）]（8）和[(F₂Bc^tBu)Ir（CO）（2,6-Me₂C₆H₃NC）]（9）in goodyields（>95%）.These complexes have been characterized by 1H,11B,13C and 19F NMR spectroscopies,infrared spectroscopy and elemental analyses.The molecular structures of complexes 4,6 and 7 have been established by single-crystal X-ray diffraction,which confirm that the coordination configuration is square planar.IR stretching value of the CO ligands and electrochemical value of the six complexes were collected.The the electronic effects of PR₃ and RNC were evaluated by value of JR-cN-R，IR stretching value of the CO and electrochemical values.3.Synthesis and characterization of π-allylpalladium（Ⅱ）complexes with bis（imidazol-2-ylidene）borate ligands.（BcR）Pd（π-allyl）（R = Mes,10;Cy,11;tBu,12）were prepared.Reactions of 10,11 and 12 with[FeCp₂][PF₆],AgPF₆ or AgBF₄ unexpectedly yielded the B-F products（F₂BcR）Pd（π-allyl）（R = Mes,13;Cy,14;15）,respectively.These complexes have been characterized by 1^H,（11）^B,（13）^C and （19）^F NMR spectroscopies and elemental analyses.The molecular structures of 10 and 12 have been established by single-crystal X-ray diffraction studies,confirming that the coordination geometry is distorted square planar configuration.