Theoretical Studies On The Structure And Properties Of Three Types Of Planar Tetracoordinated Carbon Complexes

In this thesis, we have investigated the stability, bonding of the complexes TML2 and TML2+(TM=Cu, Ag and Au) with planar tetracoordinate carbon as well as the reactions of AgL2+ with (tht)AuBr. Theoretically, the reaction mechanism of [Au(C3H2BR)]+(R=Me, t-Bu) catalyzing rearrangement reactions of allylic acetates was obtained. In addition, the stability, bonding of complexes of Cp*2M(C3H2) and Cp*2M(C2BCH3), as well as their activity toward AuCl have been carried out. The main content of this thesis includes three parts as follows:1. The structures and bonding of the complexes TML2 and TML2+ with planar tetracoordinate carbons (TM=Cu, Ag and Au; L=C3H2BCH3 and C3Me2BCMe3) have been investigated using density functional theory M06 method, in which L are the derivatives of 2-borabicyclo[1.1.0]but-1(3)-ene. The lengths of Au-C and Ag-C bonds in AuL2 and AgL2 are longer than those of in TML2+, whereas the lengths of Cu-C bonds in TML2 are shorter than those of in TML2+. The NBO analyses of TML2 and TML2+ reveal that the Cu-C bonds in CuL2 are conjugated ? bonds, whereas Ag-C and Au-C in TML2 (TM=Ag and Au) are a bonds. The first electron transition energies of TML2+ result from the d-? transition, and the wavelengths are close to 260 nm. Theoretically, the variations of the Gibbs free energies of the reactions of Ag(C3H2BCH3)2+ and Ag(C3Me2BCMe3)2+with (tht)AuBr indicate that the two reactions are thermodynamically favorable. We also theoretically obtained the stable Au(?) complexes (C3H2BCH3)2AuBr2+ and (C3Me2BCMe3)2AuBr2+ with planar tetracoordinate carbons from the reactions of Au(C3H2BCH3)2+and Au(C3Me2BCMe3)2+ with CsBr3.2. The rearrangement reactions of allylic acetates catalyzed by two kinds of Au(I) complexes ([Au(C3H2BR)]+, R=Me, t-Bu) with planar tetracoordinate carbon (ptC) have been theoretically investigated. Calculated result shows that the free energy barriers and the variations of energy of the reactions have no significant influence by the groups R bonded to B atom in the ligand of [Au(C3H2BR)]+ complexes. However, the free energy barriers and heat release of the [Au(C3H2BR)]+-catalyzed rearrangement reactions of allylic acetates in solvent are lower than that of [Au(NHC)]+-catalyzed by 2.2-2.8 and 0.5 kcal/mol, respectively. Therefore, the third type ligand towards C atom besides CO and NHC was proposed to have potential application in the coordination and organic chemistry.3. Based on the structures of the dicyclopentadienyl zirconium complex Cp*2ZrMe2 (Cp*=C5H5), we have designed and invesitigated the structures, bonding and NBO analysis of the ocene Cp*2M(C3H2) and Cp*2M(C2BCH3)(M=Ti, Zr, Hf) at the B3LYP levels. Moreover, the stable structures of the complexes formed by Cp*2M(C3H2) and Cp*2M(C2BCH3) with AuCl were obtained at the same level of theory. Calculated Gibbs free energies of formation of Cp*2M(C3H2)AuCl and Cp*2M(C2BCH3)AuCl are thermodynamically favorable. In addition, the structures of both Cp*2M(C3H2)AuCl and Cp*2M(C2BCH3)AuCl contain a planar tetracoordinate carbon (ptC).