Coordination Chemistry Of Metal Complexes And Organic Bases Studied By Electrospray Ionization Mass Spectrometry And Theory

Metal-salen complexes have showed unique catalytic activity and selectivity toward asymmetric polymerization.It have proved that the structure and Lewis acidity of metal-salen complexes have a significant effect on catalytic performance.Moreover,the coordination with various organic bases is crucial to the polymerization reaction.Therefore,the gas phase structure,reaction intermediates and reactivity has been widely attention by scientists.In this thesis,the DFT calculations and electrospray ion mobility mass spectrometry was applied to study the coordination structure and bond dissociation energies of metal-salen complexes in the gas phase.The main results are summarize as follows:The structures of metal-salen complexes and organic bases have been optimized at B3 LYP level of DFT.The most stable configuration of metal-salen complexes and organic bases have been given by calculated.All structures have slightly distorted square vertebral structures.The distortion of the spatial configuration for metal-salen complexes were cause by the coordination of organic base,spatial structure of salen ligand and electronic environment.Relative energies for the electronic states of(Salen)M(M = Cr,Fe,Co)complexes was calculated by M06 and M06 L functional.The ground electronic states are the quartet,sextet and triplet states.The ground state of electronic states for the product were consistent with metal-salen complexes.The bond dissociation energy of metal-salen complexes with DMAP and N-TrIm were calculated by B3LYP/BSSE functional.Compared with the bond dissociation energy of CID experiment,the trend of BDEs obtained by theoretical calculations consisted with the experiment results.The effects of the metal centre and ligand on the structure of the metal-salen complex and the Lewis acidity was thoroughly studied.The result shows that the Lewis acidity of different metal centers decrease in the order Al ? Cr ? Fe ? Co.Lewis acidity of the complex with o-phenylenediamine skeleton are higher than frameworks complexes.The electron-donating ligand substituents increases Lewis acidity,while the electron-withdrawing ligand substituents significantly weakens the Lewis acidity.Based on the ESI ion mobility technology,the coordination mode the spirobiindane-type bimetallic complex,biphenyl-type and phenyl-tetrahydronaphthyl bimetallic complex with various hindered organic bases was studied respectively.It was found that there are four modes for the coordination of Im to the dinuclear Co complex.The steric hindrance of the axial bridging substituent and organic base decreases the coordination stability.By the ion mobility analysis,there are two coordination options for single coordination mode: exo-cavity and endo-cavity,and four coordination options for double-coordination,exo-exo,exo/endo,exo-endo,and endo-endo,and their structures and stability were studied by quantum chemical calculation.