Germanium (pronounced jer-MAY-ni-um) is a metalloid element, a semi-metal that shares many of the physical and chemical properties of silicon. It is produced in a similar way to silicon and is used to make semiconductors and other electronic devices. Germanium is also useful for other applications, such as optical components because of its high index of refraction. In addition, it is very transparent to infrared radiation, making it important for detecting and measuring that type of electromagnetic radiation. Germanium is also used in phosphors for fluorescent lamps and has been employed in a wide variety of glass materials. It has a low mammalian toxicity and is believed to have some beneficial effects on humans when taken in small amounts as dietary supplements.
Germanium cluster anions are able to form many complexes with tetra- and hexa-coordinated elements. Two of these complexes, AdrCat2Ge (1, AdrCat = adrenaline catecholate) and AldCat3Ge(Et3NH)2 (3, AldCat = 4-formylcatecholate), were synthesized by combining germanium dioxide with the organic compounds, adrenaline and 3,4-dihydroxybenzaldehyde, respectively. Both of these complexes exhibit tetra- and hexa-coordinated germanium in their crystal structures, which were confirmed using 1H NMR spectroscopy.
The thermal behavior of these eleven-membered ring compounds was investigated using differential scanning calorimetry (DSC). Heat flow curves for the Si (9a), Ge (9b) and Sn (9c) containing ring molecules reveal that the different heteroatoms significantly influence the conformation of the rings, which can be rationalized by plane wave density functional theory calculations. Furthermore, thermogravimetric analysis (TGA) shows that the ring compounds undergo two decomposition steps at higher temperatures than silicon.