Theoretical Study Of Rare Gas Compounds Of Insertion Type And Donor-acceptor Type

In 1962,Bartlett reported the synthesis of the first xenon compound Xe⁺[Pt F₆]^-,which opened the prelude to the research of rare gas compounds in recent decades.More and more rare gas compounds are predicted and detected through theoretical calculation and matrix isolation technology at low temperature.Among the confirmed Ng-containing compounds,Ng-insertion compounds are one of the frontier areas of chemical scientific research and have received widespread attention.The compound inserted with Ng has the general formula XNg Y(where Ng is a noble gas atom,X is hydrogen or halogen or pseudohalogen,and Y is an electronegative atom or group).At the same time,the compound Ng MX(Ng is noble gas;M is a transition metal,generally Au,Cu,Ag,etc.;X is a more electronegative atom or atomic group)is another type of compounds containing noble gases,that is,donor-acceptor type rare gas compounds.It is also a research hotspot.This paper used the ab initio method and density functional method of quantum chemistry to study three systems theoretically,a.OBNg CN and its neutral and monocationic compounds with the same number of valence electrons as OBNg CN,(2)B₃Ng N₃R₆(Ng inserted into B-R bond,Ng=Kr,Xe,Rn,R=H,F)and B₃N₃Ng R₆(Ng inserted into the N-R bond,Ng=Kr,Xe,Rn,R=H,F),(3)(CH2)_nHNCu Ng⁺(n=2,3),(CH)₄NMNg and(CH)₅NCu Ng⁺(M=Cu,Ag,Au;Ng=Ar,Kr,Xe).(1)(2)is an Ng insertion type compound,and(3)is an Ng MX type compound.This paper uses different theoretical methods to analyze the bonding nature of these Ng compounds.This thesis is mainly divided into the following three parts:1.A series of compounds with XNg Y and XNg Y⁺formulas have been reported herein.We first studied the isomerization process of OBCN compounds,and then investigated the bonding properties and stability of Ng inserted into single bond of the three isomeric structures with lower energy compounds by high-level ab initio calculations.The OBNg CN inserted compounds are thermochemically stable with respect to all dissociation channels,but for the process of releasing OBCN and free Ng.Furthermore,for the OBNg CN?Ng+OBNC and OBNg NC?Ng+OBCN two dissociation processes,they are kinetically prohibited by the relatively high free energy barrier ranging from 22.720 to 31.747 kcal·mol^-1 except for the OBKr CN and OBKr NC analogues.The NBO,AIM and Energy decomposition analysis(EDA),and adaptive natural density partitioning analyses(AdNDP)based on the molecular wavefunction revealed that there are delocalized 3c–2e?-bond in the B-Ng-C moiety and a totally delocalized 5c–2e?-bond in the O-B-Ng-C-N part for OBNg CN compound,and the B-Ng bond and Ng-C bond have some covalent character.2.Quantum chemistry computations were performed at the MP2 and B3LYP levels of theory using the basis sets aug-cc-p VDZ and def2-TZVPPD to study the noble gas compounds formed by the noble gas atom Ng(Kr,Xe,Rn)inserted into the B-H/F and N-H/F bonds of the inorganic benzene B₃N₃H₆ and its fluorine derivative B₃N₃F₆.The geometrical structures were optimized and vibrational analysis was carried out to demonstrate these structures being local minima on the potential energy surface.The thermodynamic properties of the formation process of the Ng compounds were calculated.A series of theoretical methods based on the wavefunction analysis including the NBO,AIM and ELF methods and energy decomposition analysis were used to investigate the bonding nature of the noble gas atoms and the properties of the Ng compounds.The N-Ng bond is found to be stronger than the B-Ng bond,but the B-Ng bond is of typical covalent character and the?-donation from the Ng atom to the ring B atom is the predominant contribution towards the stability of the B-Ng bond.NICS calculation shows that these Ng-containing compounds are of weak?-aromaticity.3.Here we report a new type of Ng-containing compounds formed between the Ng-M group and nitrogen heterocyclic compounds,(CH₂)_nHNCu Ng⁺(n=2,3),(CH)₄NMNg and(CH)₅NCu Ng⁺(M=Cu,Ag,Au;Ng=Ar,Kr,Xe).Quantum chemistry computations were carried out to optimize their geometric structures and calculate the dissociation energies,dissociation enthalpy,and dissociation free energy change.The stability of these donor-acceptor type rare gas complexes was inspected by investigating the three dissociation processes of the these compounds into(a)Ng,M and nitrogen heterocycle C_nN(b)C_nN+MNg⁺and(c)C_nNM+Ng,which are all endothermic and nonspontaneous,these dissociation processes are also turned out to be endergonic in nature at standard state.The NBO,AIM and Energy decomposition analysis(EDA)based on the molecular wavefunction show that the M-Ng and M-N bonds have some covalent and electrostatic characters.