Technetium, a radioactive metal, forms two types of oxides with oxygen: Technetium dioxide with formula TcO2, and formula weight 129.906 and di-technetium heptoxide,TcO7, with formula weight 307.81. The latter is pale yellow and melts at about 119.5 degrees centigrade. Technetium also forms a compound with sulfur called technetium di-sulfide with formula weight 162.04.
Technetium forms two compounds with fluorine called technetium hexafluoride, TcF6, and technetium penta-fluoride, TcF5. Technetium hexafluoride is a greenish crystalline material that melts at 25 degrees centigrade while technetium pentafluoride is yellowish and melts at 50 degrees centigrade.
Two compounds are also formed with chlorine Technetium hexachloride TcCl6, which is greenish, melts at 25 degrees centigrade and has formula weight 310.623. and tetrachloride, TcCl4, which is reddish, melts at 300 degrees centigrade and has formula weight 239.718. With bromine only one compound is formed, tetrabromide, TcBr4, which is red brown, and has formula weight 417.523.
Technetium forms interesting compounds with carbonyl (CO) group. For example a technetium carbonyl complex has been useful for the labeling of bio molecules. Technetium complexes are also used in radioactive imaging. Radio active imaging is a non invasive method for actually distinguishing between a functional and a non functional heart tissue. Technetium 99m or 99mTc as it is popularly called is a radio-active compound of technetium that has proved superior to thalium 201 for cardiac imaging.