title: Electrospray mass spectrometry and tandem mass spectrometry of bimetallic oxovanadium complexes.
abstract: 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 MS mode. Fragmentation patterns of [M]*(-) were proposed, and elemental compositions of most of the product ions were confirmed on the basis of the high-resolution ESI-CID-MS/MS spectra. A complicated series of low-abundance product ions similar to electron impact (EI) ionization spectra indicated the radical character of the precursor ions. Fragment ions at m/z 214, 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 might 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 1 supported these finding, in particular, the existence of a V-O-V bridge bond.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China. wuzhijunyinger@163.com
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Wu
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Xu
authors.forename: Shi-Wei
authors.initials: SW
authors.lastname: Luo
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Fang
authors.forename: Guo-Lin
authors.initials: GL
authors.lastname: Zhang
mesh_terms: D009942:Organometallic Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014638:Vanadates / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; C075743:oxovanadium IV; D014638:Vanadates