Dichloro[hydrotris(1-pyrazolyl)borato]sulfidotechnetium-(V): The first technetium complex containing a Tc=S bond

The isoelectronic [Tc=0I3+, trans-[O=Tc=O]+, and [TFNI2+groups are characteristic functional moieties for technetium in the +5 oxidation state: all the known Tc(V) compounds belong, almost invariably, to one of the three categories of terminal oxo, trans- dioxo, or nitrido complexes. 'It has been shown that the formation of a terminal TcX multiple bond may have a key importance in the preparation of 99mTc radiopharmaceuticals through the so-called "substitution route".2 We considered the possibility to extend the range of possible types of Tc(V) compounds by preparing complexes containing new terminal TcX multiple bonds. The most obvious candidate for this purpose was the [TC=sl3+ group, which constitutes the sulfido analogue of the [Tc=O]'+ group. Many terminal transition-metal-sulfido bonds have been re- ported.