A Chlorine-Free Protocol for Processing Silicon, Germanium, and Tin

Replacing molecular chlorine and hydrochloric acid with less energy- and risk-intensive reagents would dramatically improve the environmental impact of metal manufacturing at a time when demand for metals is rapidly increasing. Germanium and tin are classified as “critical” elements based on growing demand for these elements in technological applications, lack of suitable substitutes, and, for germanium, high dispersion in the environment making extraction of the element process-intensive. This thesis describes a recyclable quinone / catechol redox platform that provides an innovative replacement for elemental chlorine and hydrochloric acid in the conversion of germanium metal or tin metal to element tetrachloride substitutes. The approach described in this thesis replaces the oxidizing capacity of chlorine with molecular oxygen, and replaces germanium tetrachloride and tin tetrachloride with air- and moisture-stable germanium or tin catecholate complexes that are kinetically competent for conversion to high-purity organogermanes and organostannanes. Also described in this thesis are the conversions of tetraethyl orthosilicate and germanium dioxide to air- and moisture-stable silicon and germanium catecholate complexes, thus replacing silicon tetrachloride and germanium tetrachloride as Group 14 precursors to organosilanes and organogermanes. The germanium catecholate complex developed in this thesis generates a pure stream of germane when reacted with hydride sources