Synthesis,Characterization And Catalytic Properties Of Trinuclear Ruthenium Carbonyl Complexes Based On Piconol Ligands

Pyridine methanols are a kind of important N,O dicentate ligands with good coordination ability.Different substituted groups of pyridine methanol can be used to form novel complexes with ruthenium metal.Among the ruthenium metal complexes,the ruthenium carbonyl complexes have attracted more and more attention because of their good stability and excellent catalytic activity.Based on the advantages of high catalytic activity and good stability of ruthenium carbonyl complexes.In this paper,the reaction of pyridinol derivatives with Ru₃(CO)₁₂ was investigated,five novel ruthenium carbonyl complexes were synthesized and their applications in oxidation reaction were investigated.This paper includes the following four parts:(1)Five pyridinol derivatives with different substituents were designed and synthesized 6-C₈H₆N-Py CR¹R²OH(R¹=R²=Me(L1H);R¹=R²=C₂H₅(L2H);R¹,R²=-(CH₂)₄-(L3H);R¹,R²=-(CH₂)₅-(L4H);R¹=CH₃,R²=Ph(L5H)).Then,the monoligand trinuclear ruthenium carbonyl complex was separated by reflux reaction with Ru₃(CO)₁₂ in THF[6-C₈H₆N-Py CR¹R²O](?₂-H)Ru₃(CO)₉{R¹=R²=CH₃(1a);R¹=R²=CH₂CH₃(1b);R¹-R²=-(CH₂)₄-(1c);R¹-R²=-(CH₂)₄-(1d);R¹=CH₃,R²=Ph(1e).The structures of the complexes were well characterized by NMR,IR and elemental analysis,and the structures of the three complexes were further analyzed by X-ray diffraction.The results show that the ligand hydroxyl proton deprotonated and coordinate with Ru atom and pyridine N atoms coordinate with one Ru atom,thus forming a stable five-member ring structure.(2)The catalytic activity of complex 1a-1d in Oppenauer-type oxidation reaction was investigated.The results showed that all the four catalysts exhibited good catalytic activity,among which complex 1a showed the highest catalytic activity.At the same time,the generality of the catalyst to secondary alcohols was investigated,and the catalytic mechanism was speculated by taking the complex 1a as an example.(3)The catalytic activity of complexes 1a,1b,1c and 1e in saturated C-H bond oxidation reaction was investigated.It was found that the four catalysts showed good catalytic activity,among which complex 1a showed the highest catalytic activity.At the same time,the universality of the catalyst for saturated C-H was investigated,and the catalytic mechanism was speculated by taking the complex 1a as an example.(4)The complex[?-?²-2-OC₆H₄-C(H)=N-C₆H₄-4-OMe)]₂Ru₃(CO)₈(1f)previously reported by our team was used as catalyst,oxidation of amine to nitrile catalyzed by the complex was investigated.It was found that the catalyst showed good catalytic activity.At the same time,the universality of the catalyst for the oxidation of amine was explored,and the catalytic mechanism was speculated.