Reactions with the technetium and rhenium carbonyl complexes (NEt(4))(2)[MX(3)(CO)(3)]. Synthesis and structure of [Tc(CN-Bu(T))(3)(CO)(3)](NO3) and (NEt(4))[Tc-2(mu-SCH2CH2OH)(3)(CO)(6)]

Starting from [MO(4)](-) (M = Tc, Re) the low-pressure (1 atm.) synthesis of the important starting material (NEt(4))(2)[MCl(3)(CO)(3)] could be improved in terms of yield and time. These M(I) complexes were used for the preparation of compounds containing the ''fac-M(CO)(3)'' moiety under ambient conditions. The substitution with the isocyanide ligand CN-Bu(t) is described. In the case of rhenium, IR spectroscopical investigations in the CO stretching region allowed the observation of the stepwise formation of [Re(CNBu(t))(3)(CO)(3)](+). It could be demonstrated that Tc-99 NMR spectroscopy allows similar investigations, although not all types of intermediates could be detected. The structure of the complex [Tc(CN-Bu(t))(3)(CO)(3)](NO3) was elucidated by X-ray diffraction analysis. Substitution with the protic ligand 2-mercaptoethanol HSCH2CH2OH revealed similar behaviour. Two intermediates were observed with IR spectroscopical methods. The final product was the dimer (NEt(4)) [Tc-2(mu-SCH2CH2OH)(3)(CO)(6)], the structure of which was determined by X-ray diffraction.