Research On The Catalytic Activity Of Ruthenium Complexes Accelerated By Non-redox Metal Ions

Ruthenium complexes are among the most-known transition metal complexes and have been applied extensively as catalysts in various catalytic reactions,however,their catalytic activity always are restrained because of the influence of their structures and reaction conditions.Non-redox metal ions can regulate the catalytic property of the active redox metal ions in various biological and heterogeneous reaction processes;meanwhile,their intrinsic roles still remain elusive.In this thesis,we have studied the interaction between non-redox metal ions as Lewis acids and ruthenium complexes and the influence of Lewis acids in various catalytic reactions,including olefin epoxidation,oxidative dehydrogenation,olefin isomerization and hydrogenation reaction.In chapter ?,we exhibit the first example of that non-redox metal ions as Lewis acid can remarkably promote the catalytic oxygen atom transfer efficiency of a ruthenium complex bearing classic 2,2'-bipyridine ligand.As evidenced by electronic absorption spectra and EPR studies,both oxidation of Ru?II?by PhI?OAc?₂ and reduction of Ru?IV?=O by olefin are slow from the view of kinetics.On the other hand,adding non-redox metal ions like Al?III?can sharply improve its oxygen transfer efficiency to 100%conversion with89.9%yield of epoxide under identical conditions.Through various spectroscopic characterizations,an adduct of Ru?IV?=O with Al?III?,that is,Ru?IV?=O/Al?III?,was proposed to serve as the active species for epoxidation.In chapter ?,inspired by the above successful strategy and dioxygen activation,we demonstrate an alternative protocol that adding non-redox metal ions to cis-Ru?bpy?₂Cl₂catalyst can remarkably improve the oxidation from Ru?II?to Ru?IV?=O with dioxygen as the oxidant and promote oxidative dehydrogenation of saturated C-C bond whereas Ru?bpy?₂Cl₂ alone is very sluggish.Combined the reaction data with characterization results,an adduct of Ru?IV?=O/Sc?III?is proposed as the key active species to improve the catalytic efficiency.In chapter ?,we demonstrate a highly efficient protocol that simple non-redox metal ions as Lewis acids can dramatically promote olefin isomerization by commercially available RuH₂?CO??PPh₃?₃ complex in open flask system.Isomerization can be accomplished within short time,and satisfying selectivity for different types of unsaturated compounds can be obtained.Meanwhile,an excellent turnover number?TON?up to 17208was achieved under air,and open flask gram scale experiments further demonstrated the efficiency of RuH₂?CO??PPh₃?₃/non-redox-metals system.Through FT-IR,GC-MS,NMR and kinetics studies,it was evidenced that the addition of non-redox metal ions induced the dissociation of PPh₃ ligand,offered unoccupied coordination sites for alkene,and formed the magnesium-bridged adduct OC-Ru-H₂---Mg²⁺as the highly active species which significantly benefited the isomerization through metal hydride addition-elimination pathway.In chapter ?,we demonstrate a highly efficient protocol that simple non-redox metal ions as Lewis acids can dramatically promote hydrogenation reaction with H₂?1 atm?as hydrogen source.The protocol are suitable for different types of unsaturated compounds and satisfying configuration selectivity can be obtained.Gram scale experiment,reuse of Ru catalyst and the synthesis of trans-products as pharmaceutical molecule demonstrated the efficiency of RuH₂?CO??PPh₃?₃/non-redox-metals system.Through FT-IR,GC-MS,NMR and kinetics studies,it was evidenced that the addition of non-redox metal ions induced the dissociation of PPh₃ ligand,offered unoccupied coordination sites for substrates,and formed the scandium-bridged adduct OC-Ru?H?-H---Sc³⁺as the highly active species which significantly benefited the hydrogenation.Last but not least,one isomerization process catalyzed by OC-Ru?H?-H---Sc³⁺was included in the this hydrogenation reaction,which benefited the product selectivity.