Complexes of technetium(I) (99Tc, 99mTc) pentacarbonyl core with π-acceptor ligands (tert-butyl isocyanide and triphenylphosphine): Crystal structures of [Tc(CO)5(PPh3)]OTf and [Tc(CO)5(CNC(CH3)3)]ClO4

A procedure was developed for preparing [99mTcX(CO)5] (X = Cl, Br, I) in a reasonable yield by high-pressure carbonylation with CO of 99mTcO4− in aqueous solutions. In the synthesis, the substantial part of the target product is accumulated in the gas phase and can be transferred from the autoclave into various solvents when relieving the pressure. Compounds [99mTcX(CO)5] (X = Cl−, Br−, I−) are stable in solutions for several hours, but in the course of longer storage they gradually decompose to give the tricarbonyl species. Substitution of the halide ligands in [99TcX(CO)5] and [99mTcX(CO)5] with tert-butyl isocyanide and triphenylphosphine was studied. The structures of the complexes [Tc(CO)5(PPh3)]OTf and [Tc(CO)5(CNC(CH3)3)]ClO4 are presented.