Theoretical Study On The Structure And Properties Of Two Types Of Lanthanide Complexes Containing Planar Four-coordinate Carbon

Since the concept of planar tetracoordinate carbon(ptC)was proposed by Hoffinann,plenty of clusters,organic molecules and complexes containing ptCs were theoretically found to be stable and a few clusters and complexes with ptC were observed experimentally.In this work,the structure,stability,chemical bond and Infrared spectra have been investigated of the two kinds of metals complexes(C3H2BR)LnCl3 and(C3H2BR)2LnCl3(R = CH3,OH,Cl,NO2)of forming by Nd,Sm,Yb and 2-borabicyclo[1.1.0]but-1(3)-ene(2BB)derivatives.Then the structures,stability,chemical bonding and aromaticity of complexes(bis-1BB)LnCl3 and(bis-2BB)LnCl3(Ln = Sc,Y,La,Nd,Sm,Dy,Ho,Yb and Lu)have been investigated using 1-borabicyclo[1.1.0]but-2(3)-ene(1BB)and 2-borabicyclo[1.1.0]but-1(3)-ene(2BB)derivatives as the ligands.The main content of this thesis includes two parts as follows:1.In this part of the work,we have designed four kinds of derivatives of 2-borabicyclo[1.1.0]but-1(3)-ene,C3H2BR(R = CH3,OH,Cl,NO2)at the DFT level of theory.We optimized the structures of complexes(C3H2BR)LnCl3 and(C3H2BR)2LnCl3 formed by C3H2BR and LnCl3(Ln = Nd,Sm,Yb)and obtained the most stable structures.Calculation results showed that these complexes contain ptC.Comparing the coordination energy of monon-adducts with bis-adducts,the monon-adducts(C3H2BR)LnCl3 is more stable.Analysised by electron topological method(AIM),the electron density and Laplacian values of Ln-C in(C3H2BR)LnCl3 are about 0.035 and 0.110.And in bis-adducts(C3H2BR)2LnCl3 are about 0.030 and 0.100.Indicating a"dosed" shell character of the covalent bond.Both(C3H2BR)LnCl3 and(C3H2BR)2LnCl3 have strong IR activity situated at around 1600 cm-1,corresponding the the stretch vibration of B-C bonds.2.Using density functional theory(DFT),the structures,stability,chemical bonding and aromaticity of Sc,Y and lanthanide complexes bearing the derivatives of 1-borabicyclo[1.1.0]but-2(3)-ene(1BB)and 2-borabicyclo[1.1.0]but-1(3)-ene(2BB),(bis-1BB)LnCl3 and(bis-2BB)LnCl3(Ln = Sc,Y,La,Nd,Sm,Dy,Ho,Yb and Lu),have been investigated.Calculated results indicate that bis-1BB and bis-2BB to LnCl3 can form stable lanthanide complexes with LnCl3.The lengths of Ln-C and Ln-N bonds in(bis-1BB)LnCl3 and(bis-2BB)LnCl3,as well as the electron density and Laplacian values of Ln-C and Ln-N bonds in(bis-1BB)LnCl3 and(bis-2BB)LnCl3 show that are Ln-C and Ln-N are covalent bond,in which the distances of Ln-C and Ln-N bonds in(bis-1BB)LnCl3 and(bis-2BB)LnCl3(Ln = Sc,Y,La,Sm and Lu)are close to those of in(bis-NHC)LnCl3.Thus,the bis-1BB and bis-2BB are analogous to the well-established bis-NHC.The NICS(0)values in the centers of the three-and six-membered rings of these complexes show that the three-and six-membered rings have strong aromaticity.In particular,(bis-1BB)LnCl3 and(bis-2BB)LnCl3 complexes are thermodynamically favorable to be formed and contain two ptCs.Thus,a family of novel stable lanthanide complexes with ptC is theoretically obtained.The research shows that the stable coordination complexes can be formed between 1-borabicyclo[1.1.0]but-2(3)-ene(1BB)and 2-borabicyclo[1.1.0]but-1(3)-ene(2BB)derivatives and f-metal by σ-electron interaction.Theoretically,two types of lanthanide metal complexes containing ptCs were predicted to be stable.