Synthesis, Structural Characterization, and Analysis of an Isostructural Bimetallic Cluster Series

Open Access
Author:
Biltek, Scott Russell
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
July 11, 2016
Committee Members:
  • Ayusman Sen, Dissertation Advisor
  • Ayusman Sen, Committee Chair
  • Raymond Edward Schaak, Committee Member
  • John V Badding, Committee Member
  • James Hansell Adair, Outside Member
Keywords:
  • Nanocluster
  • Silver
  • Bimetallic
  • Thiol Protected
Abstract:
A series of thiol-protected metal nanoclusters of the formula Ag4M2(DMSA)4 (M=Ni, Pd, Pt) was synthesized. These clusters were synthesized by wet chemical methods and identified by electrospray ionization mass spectrometry. The clusters were characterized by UV-visible spectroscopy, tandem mass spectrometry, computational methods, and single crystal x-ray diffractometry. These structural characterization techniques revealed that the series of clusters was isostructural as well as isoelectronic, meaning that any change in the cluster properties will predominately be the result of the shift in identity of the metal M down the periodic table. The properties of the cluster series as a whole were evaluated in terms of electronic structure and stability. A stepwise blue shift was found as the metal M was substituted down the periodic table. The stability of the clusters was found to be somewhat low when M=Ni, but higher for M=Pt and M=Pd, with the palladium cluster exhibiting exceptionally high stability. The synthesis of the cluster series significantly expands the diversity of existing thiol-protected nanoclusters, an important class of compounds. The observations of the shift in properties enhances the general understanding of the structure property relationships of these clusters, potentially helping to promote more rationally designed cluster synthesis in the future. During attempts to synthesize another cluster series to confirm the observed trends, a novel effect of nickel on an existing cluster synthesis was observed. The addition of nickel to this existing synthesis did not create bimetallic clusters, but instead simply altered the size of the monometallic silver clusters synthesized. The origins of this effect were evaluated and may serve as another mechanism of size control in future cluster syntheses.