Application of supersonic expansion source-Fourier transform mass spectrometry to the study of the reactions of niobium cluster cations with ethylene
Abstract
The reactions of ethylene with niobium cluster cations (Nb$\sb{\rm n}\sp+$, n = 2 $-$ 13), which are generated by laser vaporization/ionization in a supersonic molecular beam system, are studied by using Fourier transform mass spectrometry. The sequential reactions of Nb$\sb2\sp+$ are believed to involve ligand-coupling, while for the larger clusters this mechanism is less important. The bonding between the Nb atoms and the C atoms of the ligand in the product ions become stronger with increasing cluster size. One of the major product ions from the reaction of Nb$\sb4\sp+$ with ethylene, $\rm Nb\sb4C\sb4\sp+$, is especially stable and believed to be the distorted 2x2x2 fcc "nanocrystal" structure observed in supersonic expansions. The dependence of the reaction rate, saturation limit, and degree of dehydrogenation on cluster size is investigated. The possible reaction mechanism and the nature of the binding between the metal center and the ligand(s) in the reaction product ions are discussed.
Degree
Ph.D.
Advisors
Freiser, Purdue University.
Subject Area
Chemistry|Organic chemistry|Analytical chemistry
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