Study On The Ligands Synthesis Of Macrocyclic Phosphine Complexes

Macrocyclic phosphine ligands are sought as ligands for transition metal complexes because of their strong binding properties.Especially for applications requiring robust compounds,macrocyclic phosphine ligands can be used as powerful auxiliary ligands.At present,these phosphine macrocycles are mainly synthesized by cyclocondensation reactions and template syntheses.In contrast,template syntheses where components are coordinated to a transition metal template before being linked together to form the macrocycle,can improve the reaction yield greatly by controlling the stoichiometry and increasing the likelihood of the macrocyclization.Due to the macrocyclic effect,macrocyclic phosphine ligands are more stable than other ligands,which means that it is more difficult to remove them from the complex,making it difficult to replace the original metal template with other transition metals to expand the applications of the macrocyclic phosphine ligands.Most macrocyclic phosphine ligands contain asymmetric phosphine groups,so there is usually a chiral problem,resulting in the appearance of diastereomers,limiting the use of macrocyclic phosphine ligands.Two macrocyclic phosphine ligands with bidentate six-membered side rings were designed and synthesized in this dissertation,in order to solve the chiral problem caused by too many types of substituents connected to the phosphorus atom,and minimize the formation of diastereomers.Then,after the treatment of the side rings,multi-step synthesis was performed to obtain the target macrocyclic phosphine ligand,and their coordination with the metal was studied.In the first part of this dissertation,the flexible linker PBn₃ was used to synthesize and isolate the six-membered ring bidentate phosphine ligand through multi-step reaction,and the configuration of its cis and trans-isomers was determined by X-ray single crystal diffraction.After the alkylation reaction of this P₂ ligand,finally obtained a relatively pure key tetradentate open-chain phosphine ligand,and successfully coordinated with Ni Cl₂ to obtain the macrocyclic compound[Ni P₄]²⁺.³¹P{¹H}NMR spectrum characteristic signal of the typical AA'BB'system to further confirm the results;In the second part of this dissertation,we used the rigid linker Ph₂P(O)NEt₂ as the synthetic material,and ^tBu Li as the lithiating agent to promote the C-H bond converted into a C-Li bond through the ortho-lithiation.The compund Cl₂P(O)OEt undergoed a alkylation reaction to synthesize a 5,10-diphosphanthene-type ligand in 50%yield.What is special is that the four carbon atoms in the six-membered ring compound come from two benzene rings,which can play a role as side rings of the tetradentate macrocyclic phosphine ligand.The solvent,lithiation temperature and ring-closure reaction conditions of the ortho-lithiation reaction are discussed in detail,and through the attempts of various reducing reagents,5,10-diphosphanthene-type bidentate and tetradentate macrocyclic phosphine ligands with P-H bond were successfully synthesized,and their coordination chemistry with metals was also studied.