Organometallic derivatives of Rh- and Ir-substituted polyoxotungstates with Keggin structure: reactivity screening by electrospray ionization mass-spectrometry

Abstract

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Keggin‐type Polyoxometalates [PW11O39MCl]5– with Noble Metals (M = Rh and Ir): Novel Synthetic Entries and ESI‐MS Directed Reactivity Screening

“…[6] These compounds are expected to provide synergism from combining POM fragments and noble metal atoms, both known by their outstanding catalytic properties. This hypothesis is strongly supported by the known examples of their chemical behavior: for example, Ru-, Ir-and Rh-containing POMs demonstrate activity in oxidation of water [7] and various organic sub- both cases, the SCN ligands are coordinated by sulfur atoms, according to 13 C NMR and IR spectroscopic data. Gas-phase fragmentation reactions of compounds 2a and 3a were also investigated by collision-induced dissociation (CID) experiments.…”

“…In this sense, we recently employed high resolution electrospray ionization mass-spectrometry (ESI-MS) as a high throughput screening tool to monitor the reactivity at the noble metal site and to optimize the reactions conditions for the preparation of organometallic complexes with Rh-C σ bond [PW 11 O 39 Rh(R)] 5-(R = Me, Ph, Fc). [13] This situation is reminiscent to that found by Cronin's group where ESI-MS provided crucial information to distinguish Dawson-type POM with a single embedded heteroatom (P, Sb), where inherent solid state disorder over two positions made X-ray single crystal analysis ambiguous. We take advantage of this approach in this work to investigate the reactivity of the [PW 11 Figure 2 by ESI mass spectrum of the resulting mixture from the reaction of (Bu 4 N) 5 [PW 11 O 39 Ir(SCN)] (3a) and an excess of NaNCS.…”

“…[17] However, IR spectroscopy cannot be considered as sufficient diagnostic tool, as the band position may be influenced by other ligand environment, and the frequency windows for N-and S-bonded www.zaac.wiley-vch.de species may partly overlap. For additional confirmation 13 C NMR spectroscopy was used. The 13 C chemical shifts for SCN ligands fall within 112-146 ppm range.…”

Gas‐Phase Fragmentation Reactions of Keggin‐Type {PW11O39M} (M = Rh, Ir, and Ru) Polyoxometalates as Fingerprints of the Ligands Attached at the Noble Metal Site

“…A salient feature of this family of heterometallic {EW 11 O 39 M} POMs is the outstanding reactivity patterns displayed by the noble metal site. These include nitride ligand transfer for M = Ru,10 unusual direct C‐metalation of acetic acid, which can be further derivatized to obtain amide‐functionalized POMs for M = Rh,5b or straightforward access to organometallic POMs for M = Rh and Ir 5c. However, intrinsic reactivity studies at the noble metal site still remain few, in part owing to the difficulties involved in the characterization of these POMs.…”

“…Electrospray ionization mass spectrometry (ESI‐MS) is a useful experimental tool for the characterization of POMs in solution,11 particularly the family of the Keggin‐type {PW 11 O 39 M} (M = Rh, Ir and Ru) compounds 5c,7,12. Moreover, ESI tandem MS is gradually becoming a very useful analytical tool in POM chemistry.…”