Application of electrospray ionisation mass spectrometry to the study of dilute aqueous oligomeric anions and their reactions

mentioning

confidence: 99%

Intriguing Role of a Quaternary Ammonium Cation in the Dissociation Chemistry of Keggin Polyoxometalate Anions

Cao

Li²,

Zhang³

et al. 2011

“…Their characterization in aqueous solutions is complicated due to the occurrence of equilibrium aggregations and condensation reactions [4]. Undoubtedly, the aqueous chemistry of tungsten is challenging to all chemists interested in detecting inorganic ions.…”

mentioning

confidence: 99%

“…Three groups of ammonium and alkali-metal tungstates have been recognized by Gibbs [1], namely the orthotungstates [R 2 WO 4 (R ϭ Na, K)], the metatungstates [R 2 W 4 O 13 (R ϭ Na)], and the paratungstates [R 10 W 12 O 41 (R ϭ NH 4 ϩ , Na ϩ , K ϩ )].…”

mentioning

confidence: 99%

“…The methods employed for determination of tungstates include X-ray crystallography [9,10], and high performance liquid chromatography/ inductively coupled argon plasma (HPLC-ICP) mass spectrometry [11]. One of the problems in tungsten chemistry is that not many polyoxoanions crystallize without submitting themselves to considerable lattice disorder [4]. Moreover, the abundance of NMR-active nuclei in such complexes is low.…”

mentioning

confidence: 99%

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Generation and detection of gaseous W₁₂O₄₁^−· and other tungstate anions by laser desorption ionization mass spectrometry

Pavlov

Braida

Ogundipe

et al. 2009

The presence of a peak centered near m/z 2862, observed for the first time for the caged dodecatungstate radical-anion, [W 12 The aqueous chemistry of tungsten and its oxocompounds is complex and elusive. Their characterization in aqueous solutions is complicated due to the occurrence of equilibrium aggregations and condensation reactions [4]. Undoubtedly, the aqueous chemistry of tungsten is challenging to all chemists interested in detecting inorganic ions. The methods employed for determination of tungstates include X-ray crystallography [9,10], and high performance liquid chromatography/ inductively coupled argon plasma (HPLC-ICP) mass spectrometry [11]. One of the problems in tungsten chemistry is that not many polyoxoanions crystallize without submitting themselves to considerable lattice disorder [4]. Moreover, the abundance of NMR-active nuclei in such complexes is low. Not only techniques such as Raman spectroscopy, optical spectrophotometry, and polarography can only be used for relatively simple mixtures, but also their capabilities to discriminate among different anionic species are rather limited. Besides, Raman spectroscopy requires comparatively high analyte concentrations. The application of potentiometric techniques to polytungstates is rather problematic since the method demands the attainment of an Address reprint requests to Professor A. B.

“…Mixed Keggin POMs with Mo and W have been investigated previously by several research groups both theoretically [24] and experimentally [25,26]. In the present study, we use a straightforward method of preparing mixed addenda Keggin POMs, PMo 12-n W n O 40 3-(n = 0-12), for analysis by electrospray ionization mass spectrometry (ESI-MS) and examine their dissociation pathways and relative stability towards fragmentation by means of collision-induced dissociation (CID) experiments.…”

mentioning

confidence: 99%

Gas-Phase Fragmentation Pathways of Mixed Addenda Keggin Anions: PMo_12-nW_nO₄₀^3– (n = 0–12)

Gunaratne

Prabhakaran

Johnson

et al. 2015

Abstract. We report a collision-induced dissociation (CID) investigation of the mixed addenda polyoxometalate (POM) anions, PMo 12-n W n O 40 3-(n = 0-12). The anions were generated in solution using a straightforward single-step synthesis approach and introduced into the gas phase by electrospray ionization (ESI). Distinct differences in fragmentation patterns were observed for the range of mixed addenda POMs examined in this study. CID of molybdenum-rich anions, PMo 12-n W n O 40 3-(n = 0-2),generates an abundant doubly charged fragment containing seven metal atoms (M) and 22 oxygen atoms ( and M 7 O 22 2-fragment ions is different from that predicted by a random distribution, indicating substantial segregation of the addenda metal atoms in the POMs. Charge reduction of the triply charged precursor anion resulting in formation of doubly charged anions is also observed. This is a dominant pathway for mixed POMs having a majority (8-11) of W atoms and a minor channel for other precursors indicating a close competition between fragmentation and charge loss pathways in CID of POM anions.