Synthesis Of Osmabenzenes And Ruthenabenzenes Based On [5+1] Cyclization Reaction

Transition-metal-containing conjugated organometallic complexes play an important role in organometallic chemistry research because they can exhibit special structural and chemical properties as well as physical properties.In this dissertation, the synthesis and characterization of several novel ruthenabenzenes,osmabenzenes and related complexes have been described.The reactivities and properties of these complexes have also been studied.This dissertation consists of six chapters:research progress in metallabenzenes; synthesis and characterization of osmabenzenes and related complexes;synthesis and characterization of osmafuran;synthesis and characterization of ruthenabenzenes; chemical and physical properties of ruthenabenzenes;conclusion and prospect.In chapter 1,the research progress of metallabenzenes are reviewed.In this chapter,the definition of metallabenzenes and the reported synthetic methods of metallabenzenes are briefly introduced.According to the main objective of this dissertation,the research progress of metallabenzenes with the metal centre of the first and the second transition series is also reviewed in this chapter.In addition,the research objectives of this dissertation are presented.In chapter 2,the synthesis and characterization of osmabenzenes and the related complexes are described.The complex Os(CHC(PPh₃)CH(OH)CCH)Cl₂(PPh₃)₂ reacts with nucleophiles SCN^- and X^- to give the unusual osmabenzenes Os(CH-C(PPh₃)CHC(SCN)CH)(SCN)₂(PPh₃)₂ and Os(CHC(PPh₃)CHCICH)I₂(PPh₃)₂ with reactive groups on the metallacycles.Furthermore,twoα,β-unsaturated ketone complexes are obtained from the reactions and well characterized.Treatment of osmabenzene[Os(CHC(PPh₃)CHC(PPh₃)CH)Cl₂(PPh₃)₂]OH with some ligands lead to the isolation of several stable osmabenzenes.In chapter 3,the stable osmafuran Os(CHC(PPh₃)C(CH₂CH₃)O)Cl(CO)(PPh₃)₂ are synthesized and characterized.Reaction of OsHCl(CO)(PPh₃)₃ with HC≡CCH(OH)C=CH afforded the stable osmafuran Os(CHC(PPh₃)C(CH₂CH₃)O)-Cl(CO)(PPh₃)₂. Chapter 4 describes the research work on the synthesis and characterization of non-metal-coordinated ruthenabenzenes.Treatment of RuCl₂(PPh₃)₃ with HC≡CCH(OH)C≡CH,Bu₄NCl and PPh₃ at room temperature by one pot reaction produces the first stable non-metal-coordinated ruthenabenzene [Ru(CHC(PPh₃)CHC(PPh₃)CH)(PPh₃)₂-Cl₂]Cl in good yield.This result shattered the former expectation that the synthetic edfforts to prepare an isolable metallabenzene of a 4d metal which is not coordinated to another metal fragment would be futile,which will expand the research field of metallabenzenes.To study the plausible mechanism for the formation of ruthenabenzene,the reaction is carried out in presence of purposely added AcOH,and the byproduct [Ru(CO)(CHC(PPh₃)CHCH₂)(CH₃COO)(PPh₃)₂]Cl is isolated and characterized.The ruthenabenzene can even be obtained from the one-pot reaction of RuCl₃,PPh₃,and HC≡CCH(OH)C≡CH in CHCl₃,although the yield is lower.Chapter 5 describes the property studies of ruthenabenzenes.Ligand substitution reactions of the ruthenabenzene with several ligands produce a series of stable ruthenabenznes with special property.Ligand substitution reactions of the ruthenabenzene indicate that the ruthenabenzene is more reactive compared to the osmabenzene with similar structure.During the further investigation of the thermal stability of the ruthenabenzene,the dominant thermal decomposition products are isolated and well characterized.In addition,the optical response of ruthenabenzenes [Ru(CHC(PPh₃)CHC(PPh₃)CH)(PPh₃)(C₁₀H₈N₂)Cl]Cl₂ and[Ru(CHC(PPh₃)CH-C(PPh₃)CH)(PPh₃)(C₁₂H₈N₂)Cl]Cl₂ with a wide range of external stimulus including physiological anions,glucose,nucleoside analogues andα-amino acids have been investigated.In tests of ruthenabcnzcne[Ru(CHC(PPh₃)CHC(PPh₃)CH)(PPh₃)-(C₁₂H₈N₂)Cl]Cl₂ with sulfhydryl-containing amino acids,cysteine is recognised by remarkable fluorescence or absorption changes.The response product is isolated and characterized as the fist mctallabenzene containing amino acid ligand.Further study shows that titration of ruthenabenzene[Ru(CHC(PPh₃)CHC(PPh₃)CH)(PPh₃)2Cl₂]Cl with thiocyanate ion also resulted in special fluorescence response,which afford the ruthenabenzene product[Ru(CHC(PPh₃)CHC(PPh₃)CH)(SCN)₂(PPh₃)₂]Cl. In the final part of the dissertation,chapter 6,the innovation of the dissertation is concluded and the prospect of this research is presented.