Rare Earth Metals Enone Activation

The insertion of an unsaturated molecule into a metal-ligand bond is a fundamental step for many metal-promoted transformations. The study of organolanthanide insertion allows a better understanding of the relationship between the structure and the property of organolanthanides, and some complexes with novel structures or peculiar characters can be obtained, which can't be synthesized by usual way, so people can find new ways to synthesize new organolanthanides. Furthermore, people can develop new organic synthesis methods based on the lanthanide-catalyzed theory and fasten the application of organolantanides in organic synthesis.In this thesis, we firstly studied the activation of organolanthanides on ketenes, by which 37 new organolanthanide complexes were synthesized, and four new organolanthanide reactions were found. This thesis consists of six parts. The details are as follows:In chapter 1, the activation of organolanthanides on unsaturated molecules and the reactions of the ketene organometallic complexes are introduced.In chapter 2, the first activation of lanthanocene amides on PhEtCCO was studied. It was found that PhEtCCO could insert Yb-N bond of Cp2YbN/Pr2 in THF. This is the first example of ketene insertion into the Ln-N bond. Interestingly, the reactions of Cp2LnN'Pr2 with 2 equiv PhEtCCO in toluene gived [Cp2Ln{OC(C6H4(p-CHEtCON'Pr2))=CEtPh}]2 [Ln = Yb(2), Er(3), Dy(4), Y(5)] through two ketene insertion into Ln-N bond. This is a first example that the phenyl ring can undergo conjugation addition in organometallic chemistry. Further studies revealed that the coupling-insertion was competitive with the insertion of PhEtCCO into the Yb-N bond in toluene. Even if Cp2LnN'Pr2 reacted with one equiv PhEtCCO, a little coupling reaction products were also found.In order to study the effect of the nature of nitrogen-containing ligands on the above insertions, we also studied the reaction of Cp2YbNPh2 and Cp2LnPzMe2[Ln = Yb, Er, Y] with PhEtCCO and found that Cp2YbNPh2 can't react with PhEtCCO in THF, and only mono-insertion product (Cp2Yb[OC(NPh2)=CEtPh]}2 was obtained in toluene. The reaction of Cp2LnPzMe2 with PhEtCCO can give mono-insertion products {Cp2Ln [OC(PzMe2)=CEtPh]}2 [Ln = Yb(8), Er(9),Y(10)] in either THF or toluene. These results were different from the observation in the reaction of Cp2LnN'Pr2 and PhEtCCO,indicating that ligand, steric effect, electronic effect and solvents have an important effect on the insertion of a ketene into the Ln-N bond. The above ketene insertion seems to offer a convenient way to prepare lanthanide enolate complexes.Complexes 1-10 were characterized by elemental analysis, IR, and mass spectroscopies, and the structures of complexes 2, 3, 5 and 7 were also confirmed by the X-ray crystal structure analysis. The structural data revealed that two PhEtCCO molecules are incorporated in the new ligand. The newly formed enolate ligand bridges two Yb atoms through both oxygen atoms to give a formal coordination number of 8 to each metal.In chapter 3, the reactions of Ph2CCO with Cp2LnN'Pr2 were studied. It was found that Ph2CCO could double-insert into the Ln-N bond of Cp2LnN'Pr2 through the conjugation of the phenyl ring. It is different from PhEtCCO that the newly formed ligands in the coupling-insertion of Ph2CCO into Ln-N bonds didn't undergo 1,5-H shift, so the intermediates Cp2Ln[OC(C6H5CPhCON'Pr2)CPh2] [Ln = Er(ll), Yb (12), Y(13)] of phenyl-participated conjugation addition were separated. Complexes 11-13 were characterized by elemental analysis, IR, and mass spectroscopies, and the structure of complexe 11 was also confirmed by the X-ray crystal structure analysis. Complex 11 has a monomer structure, in which each Lanthanide atom is coordinated by two /75-cyclopentadienyl group, one O atom of a enolate ligand, and one bridging O atom from a second enolate ligand to form tetrahedron geometry. The coordination number of lanthanide atom is 9.In chapter 4, a series of new organolanthanide thiolate complexes [Cp2Ln(u-SEt)]2 [Ln = Yb (15), Er (16), Sm(17),...