Abstract

Synthesis and characterization of silver, molybdenum and tungsten metal organic decomposition complexes is reported. Molybdenum and tungsten are of interest, in order to expand 3D printing capabilities, by providing precursors capable of forming metal structures with superior chemical and mechanical properties. In addition to using known synthetic pathways using silver precursors, molybdenum hexacarbonyl, tungsten hexacarbonyl were reacted with three ligands: ethylenediamine, diethylenetriamine, and triethylamine to develop MOD complexes. The MOD products were characterized by NMR, FTIR and thermogravimetric (TGA) analysis. Thermal decomposition mechanisms were studied by TGA. Whereas the silver MOD complexes were found to decompose to metallic silver at temperatures lower than 200°C in both inert and atmospheric conditions, the molybdenum diethylenetriamine complex and the molybdenum triethylamine complex decomposed to molybdenum metal, and only in inert conditions at temperatures well in excess of 200°C. The other molybdenum complex, as well as all of the tungsten complexes decomposed to their oxide forms at temperatures greater than 600°C in inert and atmospheric conditions. Triethylamine-tungsten complex was found to sublime at 110°C. A hard-soft acid-base theoretical analysis indicates that, as opposed to the silver complexes where electron density is more localized on the metal center, electron density is withdrawn from the metal centers in the case of molybdenum and tungsten complexes. Additional stability provided by carbonyl p-backbonding for the carbonyl ligands prevented low temperature decomposition. As a result, this work shows that molybdenum and tungsten hexacarbonyls are not suitable starting materials for creating MOD complexes when one or more of the carbonyl groups remain on the complex. The complexes may, however, be used for metal oxide deposition instead of metal deposition.

Publication Date

8-8-2022

Document Type

Thesis

Student Type

Graduate

Degree Name

Chemistry (MS)

Department, Program, or Center

School of Chemistry and Materials Science (COS)

Advisor

Scott Williams

Advisor/Committee Member

Christina Goudreau

Advisor/Committee Member

Jeremy Cody

Campus

RIT – Main Campus

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