Technetium and Rhenium

Abstract

These two metals are less well known than many other of the second- and third-row transition metals, although interest in rhenium chemistry has recently increased. Technetium, as its name suggests, is an artifically produced element, the only such among all the d transition metals. It is thus not an element of which the majority of chemists have any direct experimental knowledge. Rhenium is a relatively rare element with few uses but with several interesting features, for example its unusual complex hydrides. These metals mark the half-way stage in the progression along the transition-metal series. The stability of the d⁵ Mn^{2 +} ion is not reflected in Tc^{2 +} and Re^{2 +}, however; the heavier metals, as usual, are more stable in higher oxidation states.