Reactivity Of Ruthenium Carbene,Vinylidene And Allenylidene Complexes With Phosphine Ligands

Transition-metal carbenes,vinylidenes,allenylidenes and carbynes have attracted much interest due to their unique structures and reactivities,as well as their significance as catalysts or reagents in organic,drug and polymer synthesis.As a representative of the late transition metals,ruthenium is not only cheap and available,but also less toxic,which has shown great advantages in organic catalytic conversion.In this dissertation,a series of ruthenium carbenes,vinylidenes,allenylidenes and ruthenium carbynes with phosphine ligands derived from the reactions of available ruthenium complexes as starting material have been synthesized.Furthermore,the stoichemetric and catalytic properties of some complexes and reaction mechanism were investigated.This dissertation consists of the following six chapters:In chapter 1,The research progress on carbenes,vinylidenes,allenylidenes and carbynes of ruthenium were briefly reviewed.In addition,the research objectives of this thesis were also presented.In chapter 2,Ruthenium alkenylvinylidene RuCl2(=C=CHC(Me)=CH2)(PCy3)2(2-1)and RuCl2(=C=CH-C(Ph)=CH2)(PCy3)2(2-2)were synthesized and studied.we found that treatment of complex 2-1 and 2-2 in the presence of CO atmosphere produced ruthenium complex RuCl2(CO)2(PCy3)2(2-3)and corresponding organic compound 2-methylbut-l-en-3-yne and but-1-en-3-yn-2-ylbenzene,respectively.The reactivity of complex 2-1 and 2-2 with acid,such as HBF4/Et2O and 2-(diphenylphosphanyl)benzenesulfonic acid has been explored.Reactions of complex 2-1 and 2-2 with HBF4/Et2O afforded cationic five-coordinated ruthenium alkenylcarbyne complexes RuCl2(≡C-CH=CMe2)(PCy3)2(BF4)(2-4)and RuCl2(=C-CH=C(MePh))(PCy3)2(BF4)(2-5),respectively.Reactions of complex 2-1 and 2-2 with 2-(diphenylphosphanyl)benzenesulfonic acid yielded neutral six-coordinated ruthenium alkenylcarbyne complexes RuCl2(≡C-CH=C(Me)2)(o-S02(O)-C6H4-PPh2)(PCy3)(2-8)and RuC12(≡ C-CH=C(MePh))(o-SO2(O)-C6H4-PPh2)(PCy3)(2-9),respectively.Furthermore,the ruthenium complexes 2-4,2-5 and 2-9 can be deprotonated by the weak base Et3N to give the alkenylvinylidene complexes 2-1,2-2 and RuCl2(=C=CH,C(Ph)=CH2)((o-SO2(O)-C6H4-PPh2)(PCy3)(2-10),respectively.At the same time,complex 2-10 can be obtained by reaction of 2-2 with sodium 2-(diphenylphosphanyl)benzenesulfonate.In chapter 3,The reactivity of the ruthenium and osmium alkenylcarbene complexes with CO ligand RuCl2(=CHCH=CR1R2)(CO)(PPh3)2(R1=R2=Ph,3-12;R1=Me,R2=Ph,3-13;R1=R2=Me,3-14)with strong base BuOK have been studied.Experiments suggest that expected product ruthenium alkenylcarbyne complexes can’t be obtained,however,unexpected ruthenium complexes 3-16～3-18 were isolated.In addition,the possible reaction mechanism of the formation of 3-16-3-18 was proposed.Different from ruthenium,the situation of osmium alkenylcarbene complex OsCl2(=CHCH=CPh2)(CO)(PPh3)2(3-19)reacted with tBuOK was very complicated.We can’t isolate any pure osmium complex,just one osmium complex 3-20 was characterized by X-ray structure analysis.Furthermore,the possible reaction mechanism of the formation of 3-20 was proposed.In chapter 4,New ruthenium complexes with 8-(diphenylphosphanyl)quinoline ligand,such as Ru(DPPQ)2C12(4-1),[Ru(u-Cl)(DPPQ)2]2[BPh4]2(4-2)and[RuCl(DPPQ)2(Py)][BF4](4-3)were synthesized.And then the catalytic properties of cycloisomerization of alkynols were investigated.Complex 4-2,with only 1 mol%loading and without any additive,was found to be catalytically active for the endo cycloisomerization of various alkynols to the corresponding 5～8 membered endo-cyclic enol ethers in moderate to excellent yields.In particular,the 7-and 8-endo heterocyclization can be achieved efficiently.The reaction mechanism was systematically studied by reaction of complex 4-2 with stoichiometric amounts of various alkynols.Seven-,six-,and five-membered ruthenium oxacyclocarbene complexes[RuCl(=CCH2C6H4CH2CH20)(DPPQ)2](BPh4)(4-12),[RuCl(=C(CH2)5O)(DPPQ)2](BPh4)(4-12’),[RuCl(=C(CH2)4O)(DPPQ)2](BPh4)(4-13)and[RuCl(=C(CH2)3O)](BPh4)(4-14)related to intermediates in the catalytic reactions were isolated.Complex 4-12 represents the first example of benzooxacycloheptylidene transition-metal complexes.For the first time,comparative studies on the modeling reactions and catalytic activity of the series of oxacyclocarbene complexes indicated that the different catalytic activity of 4-2 for the endo-cycloisomerization of different types of alkynols can be related to the reactivity of the respective ruthenium oxacyclocarbene intermediates.In chapter 5,Complex 5-1 and 5-2 were derived from the reactions of complex[Ru(u-Cl)(DPPQ)2]2[BPh4]2(4-2)with 1,1-diphenylprop-2-yn-1-ol and 9-ethynyl-9H-fluoren-9-ol,respectively.For the first time we found that reactions of complex 5-1 and 5-2 with hydrazine or hydrozone affords acrylonitrile complexes[RuCl(N-=C-CH=CPh2)(dppq)2][BPh4](5-3)and[RuCl(N-=C-CH=(FN))(dppq)2][BPh4](5-4),respectively,this reaction involves the intermolecular attack of hydrazines at the Ca atom of the allenylidene ligand.In addition,reaction of acrylonitrile complex 5-3 and 5-4 with an excess of progarylic alcohols could release the organic acrylonitriles 3,3-diphenylacrylonitrile or 2-(9H-fluoren-9-ylidene)acetonitrile along with regeneration of allenylidene complex 5-1 and 5-2.On the basis of above stoichiometric reactions,the catalytic activity of 4-2 for the transformation of terminal propargyl alcohols and hydrazines into acrylonitriles has been investigated preliminarily.The results showed that the catalytic reaction did proceed to give the desired acrylonitrile products,albeit the yield not good.Nevertheless,our results of the catalytic reactions demonstrated that it is very promised to develop new catalytic reactions for the transformation of terminal propargylic alcohols and hydrazines into acrylonitriles via allenylidene intermediates.Moreover,the relatively poor catalytic activity of 4-2 could be probably ascribed to the relative low reactivity of the monomeric[RuCl(DPP)2]+ species is in terms of reaction with the proparylic alcohol for the formation of the allenylidene complex,as well as the relatively stronger coordination of the acrylonitrile to the ruthenium center than the propargilic alcohols.Furthermore,we found that treatment of complex 5-1 and H20 in THF led to formation of the alkenyl-carbonyl complex[Ru(-CH=CPh2)(CO)(DPPQ)2][BPh4](5-5).At last,reactions of complex 5-1 and 5-2 with P-donor nucleophile such as diphenyl(phenylethynyl)phosphane(Ph2PC=CPh)leads to the formation of a-phosphonioallenyl complex[RuCl{C(Ph2PC≡CPh)=C=CPh2}(dppq)2][BPh4](5-6)and[RuCI {C(Ph2PC≡CPh)=C=C(FN)}(dppq)2][BPh4](5-7),respectively.In chapter 6,The research work of the thesis was summarized and the future prospect of this research was also presented.