Characterisation via electrospray ionisation multistage mass spectrometry of three related series of nitrido technetium complexes containing phosphinothiolate and dithiocarbamate ligands

Nine nitrido technetium compounds comprising bis-substituted Tc(N)(PS)2 (1-4) (PS = bidentate phosphinothiolate ligands) and Tc(N)(dtc)2 (5, 6) derivatives (dtc = bidentate dithiocarbamate), and mixed-ligand Tc(N)(PS)(dtc) (7-9) species were subjected to electrospray ionisation mass spectrometry and MSn experiments. Bis-substituted phosphinothiolato complexes 1-4 lead to the straightforward formation of proton bound dimers. The dinuclear species do not show, under collisionally induced fragmentation processes, the formation of monomeric units but cleavages related to the ligand framework, thereby proving the high stability of the [Tc – H+ – Tc] bond. Bis-dithiocarbamate compounds 5-6 show, instead, abundant [M + H]+, [M + Na]+ and [2M + Na]+ ions, and their collisionally induced fragmentations are highly favoured with cleavages related to the C-N and C-S bonds. During these processes, the coordination of a water molecule to [MH – L]+ fragment ions is observed, as proved by the collisional induced H2O loss detected for this species. Mixed-ligand compounds 7 and 8 show the protonated molecular ions and Na+ cationised ions with fragmentation processes related to the dithiocarbamate moiety. This behaviour indicates that coordination of ether-substituted and ester-substituted dithiocarbamates to the [TcaN] group is weaker than that of phosphinothiolates. Conversely, diethyldithiocarbamate inserted in mixed complex 9, enhances both C-N and Tc-S bonds, and fragmentation processes suggest that metal-phosphinothiolate and metal-dithiocarbamate show comparable strength.