Electrospray mass spectrometry and tandem mass spectrometry of bimetallic oxovanadium complexes

A series of six bimetallic oxovanadium complexes (1-6 only one was purified) were investigated by electrospray quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) in negative-ion mode. Radical Molecular anions [M] were observed in S mode. Fragmentation patterns of [M] were proposed and elemental compositions of most of the product tons were confirmed on the basis of the high-resolution ESI-CID-MS/MS spectra. A complicated series of low-abundance product ions similar to lectron impact (El) ionization spectra indicated the radical character of the precursor ions. Fragment ions at m/z 241 200 and 182 seem to be the characteristic ions of bimetallic oxovanadium complexes. These ions implied the presence of a V-O-V bridge bond which light Contribute to stabilization of the radical. To obtain more information for Structural elucidation three representative bimetallic oxovanadium complexes (1-3) were analyzed further by MS in positive-ion mode. Positive-ion ESI-MS produced adduct ions of [M + H](+) [M + Na](+) and [M + K](+). The fragmentation patterns of [M + Na](+) were different than those of radical molecular anions [M](-). Relatively simple fragmentation occurred for [M + Na](+) possibly due to even-electron ion character. negative-ion MS and MS/MS spectra of the hydrolysis product of Complex I supported these finding in particular the existence of a V-O-V bridge bond