| The polypyrazolylborate ligand are typical scorpion ligands.Different substituents on the pyrazole ring and boron atom lead to different electronic and steric effects of the ligand.In this paper,(9-BBN)bis(pyrazolyl)borate[(BBN)Bpx]-(Bp)with different substituents on the pyrazole ring and the([(BBN)B(7-azaindolyl)2]-)ligand were synthesized and reacted with Cu(PPh3)2NO3(I))or Ni Cl2(PPh2)3,giving eight agostic complexes.Based on the assumption that the agostic interaction can be used as a catalytic“switch”,the application of these metal complexes in catalytic carbene into N-H or B-H bond were realized.The research contents of this dissertation are as follows:(1)The ligand[(BBN)Bpx]-and[(BBN)B(7-azaindolyl)]2]-were synthesized in one pot reaction by mixing 9-boron bicyclo[3,3,1]nonane([{BBN}H]2,abbreviated as 9-BBN),pyrazole/7-azaindole and metal hydride(KH or Na H)in toluene under reflux.2)The reaction between[(BBN)Bpx]-or[(BBN)]B(7-azaindolyl)2]-and Cu(PPh3)2NO3(I)at a molar ratio of 1:1 at room temperature gives copper complexes 4-9,and their structures were determined by X single crystal diffraction.A blue solid Ni[BBN(3-Ph-pz)4BBN(OH)2]was obtained by the reaction of[(BBN)Bp3-Ph]-and Ni Cl2(PPh3)2 at a molar ratio of 2:1 at room temperature,accompanied by the B-N cleavage and hydrolysis.The reaction between K[(BBN)Bp3-Ph]and Ni Cl2(PPh3)2 can also generate complex 11.3)Single crystal structures show that complexes 4-9 contain C-H???Cu agostic/anagostic interactions.Previously,our group found that the agostic complex could be used as catalysts for the carbene insertion into N-H bond reaction.We proposed a new metal-ligand cooperative catalytic model:the“active-site”of catalysts is controlled by an C-H···M weak interaction which acts as a“switch”.The C-H bond leaves to create a vacant coordination site for interacting with the substrate and recoordinate to the metal after the product is eliminated,which means that the“switch”is turned“off”and“on”,respectively.In this paper,the agostic complexes were not only applied in catalytic carbene insertion into N-H bond,but also extended to the B-H bond.The result show that:different aromatic amines are feasible in N-H bond insertion reaction;in the catalytic B-H bond insertion reaction,diazoalkyl esters or aromatic esters as the carbene precursors and different Lewis base(such as pyridine,N-methyl pyrrolidine,trimethylamino)stabilized borane adducts can be used,giving moderate to good yields;the C-H···Cu bond plays as a switch in the B-H and N-H bond insertion reactions,and this weak interaction was influenced by the steric hindrance of the ligand and the coordinating ability of the solvent,resulting in different catalytic activity.The catalyst with less steric hindrance exhibits better result in non-coordinating solvents. |
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