Title

From polymerization initiators to precursors for solid-state materials: Syntheses and structures of a series of molecular alkali and alkaline earth metal derivatives

Date of Award

2004

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor(s)

Karin Ruhlandt-Senge

Keywords

Organometallics, Magnesium amide, Thiolates, Polymerization, Alkaline earth metal

Subject Categories

Chemistry | Physical Sciences and Mathematics

Abstract

The syntheses and characterizations of a series of molecular alkali and alkaline earth organometallics are presented.

We here report the syntheses and structures of a family of novel heteroleptic magnesium amide/thiolates by ligand redistribution chemistry involving the reaction of equimolar amounts of magnesium amide and thiolates. Utilization of thiolates with different degree of steric bulk results in either monomeric or dimeric species. We then attempted to convert the target molecules into the heteroleptic magnesium thiolate/selenolate materials that in conjunction with the analogous zinc derivatives would comprise the potential precursor for the preparation of blue-green lasers and diodes.

We also studied the hydrolysis of magnesium alkoxides and aryloxides to obtain insight into the formation of brucite, Mg(OH)2, through controlled hydrolysis of molecular alkoxide and aryloxide precursors. By applying appropriate donors, we aimed to stabilize partially hydrolyzed cluster species. The resulting cluster motif has also important applications in the biochemistry field.

Heavy alkali and alkaline earth organometallics, especially the σ-bonded compounds involving heavy group 14 ligands have important applications in synthetic and polymerization chemistry. Since little is known about the exact nature of heavy alkali and alkaline earth metal tris(trimethylsilyl)silanides and -germanides, we developed synthetic routes toward the target compounds, followed by detailed characterizations. Depending on the donor added, either contact molecules or separated ions are obtained in the solid state, whereas in solution, separated ions are observed. A family of heavy alkali metal germanium hydrides was isolated while preparing the germanides. These compounds display the rare GeH 3 - anion and are believed to be the product of ether cleavage chemistry, thus demonstrating the high reactivity of the germanides.

Compounds reported here were typically characterized using single crystal X-ray diffraction, 1 H, 13 C, 29 Si, IR spectroscopy and melting point analysis.

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