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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
The gas-phase fragmentation reactions of Keggin-type [PW11O39MCl]5– (M = Rh, Ir) polyoxometalates (POMs) featuring chloride terminal ligands have been investigated. Different adducts of the general formulas [PW11O39MCl + 2cat]3– and [PW11O39MCl + 3cat]2– [cat = alkylammonium cations (Me4N+, Bu4N+), alkali cations (Na+, K+) or protons] were subjected to collision-induced dissociation (CID) conditions. The (cat)Cl (cat = H+, Na+ or K+) fragments were released as a common fragmentation pathway and were taken as a fingerprint of the ligands attached at the noble metal site. Other {PW11O39ML} POMs (M = Rh, Ir) with L = thiocyanate, nitrite, methyl, phenylacetate or phenyl were identified on the basis of CID experiments. Coordination studies of thiocyanate anions and CO to {PW11O39Ru} POMs to yield the new compounds [PW11O39RuSCN]5– and [PW11O39RuCO]4– are also reported. CID experiments were also used to validate that thiocyanate and CO ligation at the Ru metal site had occurred.