Theoretical Studies On Structural Characteristics And Nitrogen Activation Of Electron-Rich Reactor

As known,one of remarkable properties of C60 is the outstanding electron-accepting ability,which makes fullerene a special molecule that is able to form a stable anion.After fluorination,C60F60 and its partially fluorinated derivatives exhibit extremely larger electron affinities than C60 because all the C-F dipoles can focus their positive ends towards the cage interior,creating extremely strong electron-attractive potential for trapping excess electrons.Excess electron combines with the fluorocarbon cage to form the solvated electron.Different from the traditional strongly bound electrons,the solvated electron is a kind of weakly bound electrons with obvious Rydberg characteristic.Due to its special dispersivity and reducibility,the solvated electron has attracted an amount of attentions in the fileds of nonlinear optical materials,superconducting materials and chemically inert species reduction.Although the structures,properties and states of solvated electron in various solvents have been explored by many researchers,studies involving the J-coupling and N2 reduction are scarce,which needs further explorations.Due to the solvated electron in fluorocarbon cage having high stability and strong reducibility,thus in this paper,the effect of solvated electron on the Internuclear Jcouplin of fluorocarbon cage is systematically investigated using the density function theory and the natural bond orbital analysis.Futhermore,the activation of nitrogen by solvated electron in perfluorocarbon cage is preliminarily characterized.The main conclusions and innovations as follow:1.Unique Solvated Electron State and Its Remarkable Enhancement Effect on Internuclear J-couplings in Fluorocarbon Cage Electron Clathrates:The excess electron is trapped in the fluorocarbon cage to form the solvated electron system(em@CnFn,m=1,2 n=20-28,36,60),which significantly affects the electronic structure and J-coupling of fluorocarbon cage.Density function theory and natural bond orbital analysis are used to analyze that how the solvated electron affects N(me)JFF-coupling constants in em@CnFn.The ground-state orbital of solvated electron in em@CnFn is a reverse 2s-orbital(rev-2s),which is attributed to the unique cage-shell orbitals which allow permeation of solvated electron into the carbon skeleton and C-F bond regions,expanding and modifying the orbital tail of solvated electron.Such a rev-2s distribution not only creates the through-solvated electron coupling(TSE),but improves the through-bond and through-space couplings(TB+TS).What’ more,owing to the cooperation and competition of the TSE and TB+TS channels,we observed an interesting quasi-hemisphere regularity:when the centering angle is smaller than 80°(∠F(?)F<80°),the TB+TS couplings act as the main coupling and do larger negative contribution to the total N(me)JFF,N(me)JFF decreases with the straight-line distance between the F atoms(dFF)and the sign is negative;when ∠F(?)F>80°,the TSE coupling serves as the main coupling and does larger positive contribution to the total N(me)JFF,N(me)JFF increases with dFF and the sign is positive.Additionally,increasing the number of solvated electrons can increase the s-electron densities over the coupling pathway,thus N(me)JFF enhances:(2e)JFF>(e)JFF>JFF.This work not only provides novel insights into the structures and properties of solvated electrons,but also helpful information for the design of the esol--based NMR probes and electronic devices.2.F Substitution Effect Induced by Solvated Electron and Its Enhancement on LongRange Internuclear JFF-couplings in Fluorocarbon Cage Electron Clathrates:Due to the perfluorocarbon cage only can bind two solvated electrons at most,which limits the enhancement of the J-coupling constants.Fortunately,we found that the solvated electron in partial fluorocarbon cage induces an F substitution effect,which further enhances the Jcoupling constants and exhibits unique J-coupling rules.In this work,we reported that the influence of F substitution effect on the electronic structures and long-range JFF-coupling constants using the density function theory and natural bond orbital analysis.Results indicate that the ground-state orbital of solvated electron in e@C20FxH20-x(x=6,8,12)is a mixed s-type orbital with the coexistence of 2s with 3 s,the 2s character occurs in the C-F bond zones and the 3s character in the C-H bond zones,which is attributed to the difference between C-F antibonding orbital and C-H antibonding orbital.Additionally,adjusting the number of F atoms of e@C20FxH20-x and the chemical environment around the coupled nuclei can further enhance the long-range 7eJFF-coupling constants.On the hand,the 7(e)JFF of e@C20FxH20-x(x=6,8,12,16,20)firstly increases and then decreases as the number of F atoms increase,and the 7(e)JFF in e@C20F8H12 is the conversion.Most importantly,7(e)JFF in e@C20F8H12 is much larger than that of e2@C20F20.On the other hand,the more the number of F atoms around the coupled nuclei,the larger the long-range 7eJFF-coupling constants.These phenomenoa orginate from the enhancing in Occ(σ*C-F)of e@C20FxH20-x(x=6,8,12,16,20),generally speaking,the greater the Occ(σ*C-F),the stronger the 7(e)JFF.This work not only provides further theoretical knowledge for the structural characterization of fluorocarbon cage electron clathrates,but also research ideas for solving the difficulties of NMR quantum computer.3.Nitrogen Activation Induced by the Confinement of Fluorocarbon Cage Electron Clathrates:Although N2 has a strong adverse electron affinity in the free gas phase,dopting the N2 into the perfluorocarbon cage electron clathrate,its electron affinity will be greatly enhanced,and the solvated electron will be directly added to the π antibond orbital(π*)of N2 to form N2-,which activates the N-N bond for the next N2 reduction.In this paper,the activation of N2 by solvated electron in perfluorocarbon cage was studied using the density functional theory and the ab initio molecular dynamics simulation,which laid a foundation for the next N2 reduction.Results show that in(N2,e)@C60F60,due to the combination of N2 with solvated electron,the NBO charge of N2 in(N2,e)@C60F60 is negative,the N-N bond is elongated,the type of N-N bond evolves from the triple bond of N2 and N2@C60F60 to the double bond of(N2,e)@C60F60,and the N-N bond stretching vibration frequency redshift.What’s more,the distribution of solvated electron on N2 exhibits the π antibond orbital characteristic.These phenomena indicate that N2 in(N2,e)@C60F60 is activated by single solvated electron.Additionally,we found that increasing the number of solvated electrons in the perfluorocarbon cage will not further improve the activation degree of N2.On the contrary,the combination of solvated electrons with N2 will be weakened due to the repulsion and competition between the two electrons,which makes the solvated electrons unable to activate N2.This work not only provides a new idea for the subsequent nitrogen reduction,but also expands the application of solvated electrons as high-energy reductants of chemical inert substances.In summary,in this paper,the density function theory and the natural bond orbital analysis are utilized to systematically explore the structures,electron distributions,properties and application of fluorocarbon cage electron clathrates,detailedly discussing the effect of solvated electron on the J-coupling and N2 activation in fluorocarbon cage.Executing a deep of exploration on the various potential properties of fluorocarbon cage electron clathrates will provide an important theoretical basis for the practical application of electron clathrates in nonlinear optical materials,nuclear magnetic resonance probes and the nitrogen reduction.