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

Abstract

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 MS(n) experiments. Bis-substituted phosphinothiolato complexes 1-4 lead to the straightforward formation of dinuclear species reasonably originating from proton bound dimers. These 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 and 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](+) product ions is observed, as proved by the collisionally induced H(2)O loss detected for this species. Mixed-ligand compounds 7 and 8 show the protonated molecules and Na(+)-cationised ions with fragmentation processes related to the dithiocarbamate moiety. This behaviour indicates that coordination of ether- and ester-substituted dithiocarbamates to the [Tc [triple chemical bond] N] 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.

Technetium and Rhenium in Five-Coordinate Symmetrical and Dissymmetrical Nitrido Complexes with Alkyl Phosphino-thiol Ligands. Synthesis and Structural Characterization

“…ESI(+) mass spectra of mixed-substituted compounds showed the protonated ([M + H] + ) and the cationized [M + Na] + molecular ion peaks. Under collision experiments, [M + H] + exhibited fragmentation processes mainly related to the dithiocarbamate moiety …”

“…In all reported Tc-and Re-phosphinothiolate complexes, the substituents at P were invariably aromatic groups, either phenyl or substituted phenyl. 17,25 It is interesting to note that variation of the carbon chain joining the P and S donor drives the coordination geometry around the metal center, even if the five-coordinate geometry is generally favored. 7 In all these five-or six-coordinated complexes, the metal coordination sphere is completely saturated by the phosphinothiolate ligand, while the corresponding monosubstituted compounds were never achieved.…”

“…Under collision experiments, [M + H] + exhibited fragmentation processes mainly related to the dithiocarbamate moiety. 17 The appearance of a singlet in the 31 P NMR spectra, (Figure S1b,d, Supporting Information) was diagnostic for the formation of mixed-substituted complexes. As observed in monosubstituted complexes, the 31 P signal was significantly broadened as well as slightly downfield shifted for technetium species compared with the corresponding signal in rhenium analogs.…”

Electrospray mass spectrometric studies of the complexational behavior of maleonitrile thiacrown ethers with various metals

“…Electrospray ionization mass spectrometry (ESI‐MS) is a well‐established method for studying complexes in the gas phase and a number of crown ether complexes have thus been studied1–4 using this methodology as thiacrown ethers form stable metal complexes with a range of transition metal ions 5–10. Moreover, the complexational behavior of transition and heavy metal ions with different thiacrowns has also been investigated,11–15 and it has been shown that the equilibrium distribution of thiacrown ether complexes in solution is reflected by the abundances of the ions, e.g. [M+H] + or [M+Na] + , in the mass spectra of the complexes obtained by ESI‐MS 16–18.…”

Estudo da degradação de reagentes liofilizados para radiodiagnóstico por cromatografia líquida de alta eficiência (HPLC) e espectrometria de massas (MS)

“…A formação de dímero de ECD observada na FIG.56 pode ser associada à presença de umidade no API. Os clusters de água são separados pela energia de ionização aplicada e as espécies de ECD reagem entre si em um processo de dimerização(87,88).…”