The Spectroscopic Study Of Heteronuclear 14 Group Elementsiron Carbonyl Anions And Scandium-Nickel Carbonyl Anions

Infrared photo-dissociation spectroscopy（IRPD）is a wildly used method to study the cluster ions in the gas phase.It has high sensitivity and can give the vibrational information of mass selected ions.In this dissertation,the A₂Fe（CO）₃^-（A=Ge,Sn,Pb）and ScNi（CO）_n^-（n=2-6）cluster anions were produced by the laser vaporization supersonic cluster ion source and characterized by the mass spectrometry and infrared photo-dissociation spectroscopy.In comination with theoretical calculations,their structures were determined,and their bonding characters were discussed.This study will improve our understanding of the main-group-metal-transition-metal carbonyls anions and scandium-transition-metal carbonyl anions.It also provide new insight into the chemical properties of the heteronuclear metal clusters and their important roles in the surface catalysis.The main work is as follows:（1）The experimentally observed A₂Fe（CO）₃^-（A=Ge,Sn,Pb）anions were characterized to have Cs symmetry involving all the four CO ligands coordinated on the Fe center.The extra negative charge of the A₂Fe（CO）₃^-（A=Ge,Sn,Pb）anions is mainly located on the Fe（CO）₃ group.The iron center had 15-electron configuration and the Fe（CO）₃^-group is analogy to a group-15 element atom with big size,which binds to two carbon atoms.The A₂Fe（CO）₃^-（A=Ge,Sn,Pb）anions can be regard as been formed between Fe（CO）₃^-group and the A₂ dimmer with three metal-metal single bonds and with the iron center having 17-electron configuration.（2）The experimentally observed ScNi（CO）_n^-（n=3-6）cluster anions were been regared to formed between Ni（CO）3 groups and Sc（CO）n groups with different combinations.Natural charge population analysis showed that the positive charge of the ScNi（CO）_n^-（n=3-6）cluster anions,mainly located on the Sc atom and Sc（CO）_n group,and the Sc atoms transfer electron densities to the CO ligands.The frontier molecular orbitals of the isomers with side-on-bonded,or bridging carbonyls,are delocalizedπorbitals mainly involving the metal–carbon unit,which stabilize the whole isomers.For the isomer with only terminal carbonyls,the Sc-Ni is aσtype single bond,which is formed between a Sc 4s,3d hybrid orbital and a Cr 4s,4p,3d hybrid orbital.The Sc-Ni bonding strength decreased as more CO terminal bonded to the Sc atom,which is consistent with the evolution of the predicted Sc-Ni distances.