Germanium

Abstract

Organogermanium compounds have been studied less than their silicon and tin counterparts, and similar large-scale commercial or industrial uses have not been found for them. Most of the compounds known may be regarded (and are named) as derivatives R _n GeX_4-n, of germane, with one to four Ge-C bonds, and functional groups or atoms X occupying the remaining valences. Among such derivatives, the halides are valuable intermediates in the preparation of other compounds. Covalency 4 is a feature of almost all these compounds, including derivatives of the higher germanes, in which chains or rings of germanium atoms occur. The association of molecules through bridging alkyl groups, such a feature of many derivatives of elements in the first three Groups of the Periodic Table, is not observed at all with alkyl derivatives of germanium, tin, or lead. Association through functional groups, involving coordination numbers greater than 4, known to occur with a number of tin compounds, is not important for germanium. Compounds that may ionize in solution, the alkali metal derivatives, R₃GeM, are known; these too are useful intermediates in syntheses. Di(alkali metal) germanes, R₂GeM₂, also exist. Organogermyl groups have been attached to a number of other metals, including magnesium, tin, copper, silver, gold, platinum, iron, and manganese.