The Reaction Of CO₂ With Atomic Transition Metal M^+/0/- Ions:A Theoretical Study

With the progress of industry-improvement,modern societies are confronted with aggravating the depletion of petroleum resources and burning fossil fuels.Especially,the gradually increasing emission of CO2 gas into the atmosphere from burning fossil fuels has been considered to be one of the main contributors of climate changes and global warming and leading to ultimately environmental deterioration.However,on the other hand,it is well known that CO2 can be appealing as economical C1 chemistry for replacing the non-regenerated energy to synthesize useful clean energy resources relies to its natural abundance,stable chemical property,nontoxic and nonflammable as a renewable carbon source,which attracting extensive interests to develop effectively activated routes for converting CO2.A high-level computational study on C=O bond of carbon dioxide by bare M+/0/-has been tried,in this article,benchmarks of various of Hartree-Fock exchange fractions such as HFS,B97D3,BP86,TPSS,B3LYP,TPSSh,03LYP,?B97XD,X3LYP,PW1PW,PBE1PBE,M06,BMK,BH&HLYP,B2PLYP,?B97 and M11 have also been carried out.Furthermore,the gold-standard CCSD(T)method was used to benchmark density functionals.The results revealed that the early transition metal cations and atom(Sc to Mn)have high-spin ground states for the linear[M-OCO]+ isomer,while they have low-spin ground states for the OAT[OM-CO]+isomer.For Sc,Ti,V,high-spin states are more stable for[M-OCO]+/0 and low-spin states for[OM-CO]+/0.So we could predict early 3d transition metal cations and neutrals(Sc,Ti and V)favor OAT reaction 1a.On the contrary,the late transition metals cations from Cr to Zn,[M-OCO]+ are more stable than[OM-CO]+,that is,the late transition metals cations favor binding formation,reaction 1b.Moreover,transition metal atom(Cr to Mn)could neither carry out OAT nor efficient adduct except Fe has relative stable[Fe-OCO]0.In anionic system,for early transition metal ions(Sc to Cr),[OM-CO]-are more stable than[M-OCO]-,while the others favor binding formation[M-OCO]-.Furthermore,CO2 adsorption to early 3d transition metal anions has been calculated to be much more stable than those of their cationic and neutral analogues,while late 3d transition metal cations are much more stable than those of their anionic and neutral analogues.In most case,reaction enthalpy and energy barrier of OAT for the cationic system is the highest,and the anionic system is the lowes.