Award Date

5-1-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Radiochemistry

Department

Chemistry

First Committee Member

Kenneth R. Czerwinski

Second Committee Member

Frederic Poineau

Third Committee Member

Alfred P. Sattelberger

Fourth Committee Member

Ralf Sudowe

Fifth Committee Member

Thomas Hartmann

Number of Pages

230

Abstract

In this work, the synthetic and coordination chemistry as well as the physico-chemical properties of binary technetium (Tc) chlorides, bromides, and iodides were investigated. Resulting from these studies was the discovery of five new binary Tc halide phases: α/β-TcCl3, α/β-TcCl2, and TcI3, and the reinvestigation of the chemistries of TcBr3 and TcX4 (X = Cl, Br). Prior to 2009, the chemistry of binary Tc halides was poorly studied and defined by only three compounds, i.e., TcF6, TcF5, and TcCl4. Today, ten phases are known (i.e., TcF6, TcF5, TcCl4, TcBr4, TcBr3, TcI3, α/β-TcCl3 and α/β-TcCl2) making the binary halide system of Tc comparable to those of its neighboring elements.

Technetium binary halides were synthesized using three methods: reactions of the elements in sealed tubes, reactions of flowing HX(g) (X = Cl, Br, and I) with Tc2(O2CCH3)4Cl2, and thermal decompositions of TcX4 (X = Cl, Br) and α-TcCl3 in sealed tubes under vacuum. Binary Tc halides can be found in various dimensionalities such as molecular solids (TcF6), extended chains (TcF5, TcCl4, α/β-TcCl2, TcBr3, TcI3), infinite layers (β-TcCl3), and bidimensional networks of clusters (α-TcCl3); eight structure-types with varying degrees of metal-metal interactions are now known. The coordination chemistry of Tc binary halides can resemble that of the adjacent elements: molybdenum and ruthenium (β-TcCl3, TcBr3, TcI3), rhenium (TcF5, α-TcCl3), platinum (TcCl4, TcBr4), or can be unique (α-TcCl2 and β-TcCl2) in respect to other known transition metal binary halides. Technetium binary halides display a range of interesting physical properties that are manifested from their electronic and structural configurations. The thermochemistry of binary Tc halides is extensive. These compounds can selectively volatilize, decompose, disproportionate, or convert to other phases. Ultimately, binary Tc halides may find application in the nuclear fuel cycle and as precursors in inorganic and organometallic chemistry.

Keywords

Fission products; Halides; Radiochemistry; Technetium compounds; Transition metal halides

Disciplines

Chemistry | Radiochemistry

Language

English


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