Theoretical Study On The Interaction System Of Covalent And Non-covalent Metallic Bonds

Intermolecular interactions have been a hot topic of research in recent years,owing to their important influence in supramolecular chemistry,molecular self-assembly and materials science.Initially,people focused on the weak interaction of hydrogen-bond and halogen-bond,etc.Recently,however,the metallic-bond interactions（B···M-X）formed by coinage metal halides with other Lewis base molecules B have also attracted extensive attention due to its significance in the fields of crystal engineering and catalytic reaction.And other non-covalent metallic-bond interactions such asπ-type（π···M-X）and pseudo-πtype（pseudo-π···M-X）complexes have also been studied.A large number of experimental and theoretical studies have shown that the configuration of metallic-bond interactions were similar to hydrogen-bonds（B···HX,X=F,Cl,Br,I）and halogen-bonds（B···XY,XY are dihalogen molecules）.For example,Papadopoulos et al.proposed the golden-bond for the first time through theoretical research on the HF/H2O···AuOH complexes.Legon’s gruop also synthesized and characterized the series of complexes C2H2··MCl and C4H4··MCl（M=Cu,Ag）through by experimental methods.In this work,the type of interaction and essential characteristics of the metallic-bond systems formed by the coinage metal halide（MX）and several Lewis base molecules（PH2B/C2H2/C3H6/PH2OH,etc.）are systematically theoretical studied,and different theoretical methods and basic sets were used to optimize the structure and analyze the properties.The main content of this thesis includes the following parts:（1）The equilibrium structures,interaction energies and binding properties of ternary BrF（ClF）···AgX···BrF（ClF）（X=F,Cl,Br）complexes and the corresponding binary systems have been studied by DFT method at the X3LYP/aug-cc-pVQZ level.Through the analysis of charge transfer,topological properties and orbital interaction,the cooperative effects of the F···Ag bond and the X···Br（Cl）halogen bond in the ternary system were discussed.The results show that the cooperative effect of X···Br（Cl）halogen-bond on F···Ag bond was greater than that of F···Ag bond on X···BrB（Cl）halogen bond;and compared with the corresponding binary complexes.It was found that the interaction distances of the ternary complexes are shorter and the interaction energy are stronger.（2）The intermolecular interactions of BH₂P···MX（B=H,CH₃,F,CN,NO₂;M=Cu,Ag,Au;X=F,Cl,Br,I）were studied by ab initio method.The results show that the interaction energies are in the order Ag<Cu<Au and increased with the decrease of R_P···M.Interaction energies are strengthened when electron-donating substituents B connected to BH₂P,while electron-withdrawing substituents produce the opposite effect.For example,the strongest P···M bond（-70.95 kcal/mol）was found in CH₃H₂P···AuF,and the weakest one was in NO₂H₂P···AgI.The resonance-type of 3c/4e hyperbond P:-M-:X was recognized by NRT and NBO analysis;the competition of P:M-X?P-M:X resonance structure mainly came from superconjugation interaction;the bond order of b_P-M and b_M-X is in line with the conservation of the idealized relationship b_P-M+b_M-X≈1.In all MF-containing complexes,the P-M:F resonance structure accounts for a large proportion which leads to the covalent characters for partial ionicity of MF.The interaction energies of these Cu/Ag/Au complexes are substantially stronger than that of the halogen-bond complexes and close to strong hydrogen-bond.（3）The interactions inπ/aromaticπ/pseudo-πtype complexes of（C₂H₄/C₂H₂/C₆H₆/（CH₂）₃···MX（M=Cu,Ag,Au;X=F,Cl,Br,I））were studied by theoretical calculation at the level of wB97XD/aug-cc-pvtz,compared with the isomorphous(C₂H₄/C₂H₂/C₆H₆/（CH₂）₃···HX/YX（X=F,Cl,Br;Y=Cl,Br）complexes.The results indicate that the interactions ofπ/aromatic-π/pseudo-π···Cu/Ag/Au bonds contributed to the stability of the dimers except for（CH₂）₃···AuF.The interaction energies of all complexes reduced with the decrease of electronegativity of halogen atoms（F>Cl>Br>I）,the magnitude of the interaction intensity wasπ···M>aromatic-π···M>pseudo-π···M>π/aromatic-π/pseudo-π···H/Y and Cu>Au>Ag;and the intensity of the interaction energies in C₂H₄/C₂H₂/C₆H₆/（CH₂）₃···MX complexes changes in the order of Au>Cu>Ag.The charges transfer of most complexes from the bonding orbital(π_C-C)of the C-C bonds to the anti-bonding orbital of the MX monomers,and back-donation from the occupied orbitals of metal atoms intoπ*_C-C antibonding orbital of theπ-system.The interaction energy（-89.31kcal/mol）of（CH₂）₃···AuF is the highest in all complexes,and the charge transfer direction isσ_C-Au?σ*_C-Au.The results reveal that（CH₂）₃···AuF forms two stable coordination bonds.（4）Complexesation of phosphine oxide（H₃PO）,cis-phosphonic acid（C-PH₂OH）and trans-phosphonic acid（T-PH₂OH）with MX（M=Cu,Ag,Au;X=F,Cl,Br）were investigated by means of ab initio MP2/aug-cc-pVTZ method.For the phosphinic acid complexes,two types of Regium-bond interactions（trans and cis）were observed,which are very easily transformed from one type to another due to a low energy barrie.The variation of interaction energies are in the order of Au>Cu>Ag,F>Cl>Br.There are two main resonance types of P:MX（ωI）?P-M:X（ωII）,O:MX（ωI）?O-M:X（ωII）are recognised by NBO and NRT analysis;The competition between theωI?ωII resonance structures mainly comes from the super-conjugated interaction.In all the phosphorus-sharing complexes,the P-M:X resonance structure accounts for a large proportion,resulting in obvious covalent characteristics of the complexes.All complexes are also described in terms of their electron density characteristics.