Synthesis And Structural Characterization Of Organometallic Multi-nuclear Clusters With 1, 2-Dichalcogenolato-o-Carborane Ligands

The synthesis and properties of dicarba-closo-dode-caboranes were first reported at the end of 1963 in both the United States and the USSR.Their chemistry is one of the most complete in the field of boranes and heteroboranes.The use of carborane clusters has been directed toward many applications in organometallic chemistry.The dissertation describes the synthesis and structural characterization of Organometallic complexes with 1,2-dichalcogenolato-1,2-dicarba-closo-dodecaborane ligands,with emphasis on the synthesis of those complexes containing metal-metal bond.The dissertation consists of the following listed contents:1.A number of 16-electron mononuclear half-sandwich Cobalt complexes containing a bidentate,chelating 1,2-dichalcogenolato-1,2-dicarba-closo-dodecaborane ligand had been synthesized and well characterized.X-ray structure revealed that there was a pseudoaromatic metalladichalcogenolene five-membered ring.These complexes could serve as promising precursors for the synthesis of mixed Cobalt-Metal clusters,due to both their unsaturation at the metal atom and the bridging or chelating properties of the sulfur or selenium atoms respectively.So we use them to react with different low valent transitional metal complexes.First are the Mo(CO)₃(NC₅H₅)₃ and W(CO)₃(NC₅H₅)₃,and get different results as di- or tri-nuclear Cobalt-Metal cluster complexes.In this serial of reactions,the cobalt center is reduced. And the structures of these complexes have been determined by X-ray crystallography.2.The 16-electron half-sandwich cobalt complexes 3S～4Se can react with Fe(CO)₅,Co₂(CO)₈,Ni(COD)₂,and get various results.The prototype of hetero-binuclear complexes containing metal-metal bondings were obtained from the reactions of Fe(CO)₅.The molecular structures of {Cp^*Co[S₂C₂(B₁₀H₁₀)]}[Fe(CO)₃] and {CpCo[S₂C₂(B₁₀H₁₀)]}[Fe(CO)₃]have been determined by X-ray crystallography. But with Co₂(CO)₈ get a close Co₃ triangle geometry complex with three Co-Co bonds.And after radiation the triangle geometry can shift to linear Co₃ geometry with two Co-Co bonds.Different reaction condition can lead to different results,and the difference in the cyclopentadiene part matters in this kind of the reactions.Complex 3S react with Ni(COD)₂ get the only linear trinuclear Co-Ni-Co product,and the structure has been solved by the X-ray analysis.3.Four binuclear iridium complexes with a chelating 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolate ligand[Ir₂(COD)₂(μ₂-E₂C₂B₁₀ H₁₀)][(Cp^*Ir)₂(μ₂-E₂C₂B₁₀H₁₀)][E=S,Se]have been synthesized through different method.The formal oxidation state of iridium in complexes[Ir(COD)Cl]₂ and (Cp^*IrCl)₂(μ₂-Cl)₂ areâ… andâ…¡respectively due to the different electron donor coordinated to the iridium center.All four complexes are characterized by IR,¹H,¹³C, ¹¹B-NMR spectra and Elemental analyses.The molecular structures of the binuclear iridium complex have been determined by X-ray crystallographic analysis,only [(Cp^*Ir)₂(μ₂-E₂C₂B₁₀H₁₀)]shows the metal-metal interaction between the two iridium atoms.Reactions of 3 or 4 with[Rh(COD)Cl]₂ can afford binuclear complexes, [Rh₂(COD)₂(μ₂-E₂C₂B₁₀H₁₀)]as red solid.In this serial of reactions,no CoRh or CoIr metal clusters were obtained,indicates the cobalt is weaker in the bonding with thiolate atoms than rhodium and iridium.4.Two rhodium complexes with sulfur or oxygen functionalized cyclopentadienyl ligands[η⁵-C₅H₄(CH₂)₂SCH₂CH₃]RhI₂,{[η⁵-C₅H₄(CH₂)₂OCH₃]RhI₂}₂ along with their cobalt analogue have been synthesized and characterized by IR,¹H-NMR spectra and Elemental analyses.The molecular structure of both the rhodium complexes have been determined by X-ray crystallographic analysis.Complexes with a pendent arm on cyclopentadienyl ligand have been tested as catalysts for ethylene and norbornene polymerization in the presence of MAO.Four Complexes kept high activities of ca. 10⁶ g PE·mol^-1Rh·h^-1 with morderate molecular weight(Mw≈10⁵ g·mol^-1) of polyethylene in the ethylene polymerization and exhibits moderate catalytic activity (10⁵ g PNB·mol^-1Rh·h^-1) for norbornene polymerization.Catalytic activities, molecular weights of polyethylene have been investigated under the various reaction conditions.