Coordination-Induced Condensation of [Ta₆O₁₉]^8–: Synthesis and Structure of [{(C₆H₆)Ru}₂Ta₆O₁₉]^4–and [{(C₆H₆)RuTa₆O₁₈}₂(μ-O)]¹⁰⁻

Abstract

Reaction of [(C6H6)RuCl2]2 and Na8[Ta6O19] gives two new hybrid organometallic POM complexes, Na10[{(C6H6)RuTa6O18}2(μ-O)]·39.4H2O (Na10-1) and Na4(trans-[{(C6H6)Ru}2Ta6O19]·20H2O (Na4-2). In both cases the half-sandwich fragments {(C6H6)Ru}(2+) are coordinated as additional vertices to the {Ta3(μ2-O)3} triangles of the hexatantalate. According to NMR and ESI-MS data, the dimeric complex [{(C6H6)RuTa6O18}2(μ-O)](10-) dissociates in water with the formation of monomeric [(C6H6)RuTa6O19](6-) species (1a). X-ray structural characterization and aqueous speciation of the complexes by (13)C, (1)H, and DOSY NMR; ESI-MS; and capillary electrophoresis (CE) have been carried out.

Extraction of Nb(v) by quaternary ammonium-based solvents: toward organic hexaniobate systems

“…Methyltrioctylammonium chloride (≥97%) and Aliquat® 336 were purchased from Sigma Aldrich. Aliquat® 336 is a mixture of methyltrioctylammonium, methyldioctyldecylammonium, methyloctyldidecylammonium and methyltridecylammonium chloride, the major component 23 Na NMR spectra were acquired on a Bruker Advance 400 MHz spectrometer. 23 Na NMR spectra were referenced to a 1.0 M NaCl aqueous solution.…”

“…The co-extraction of alkali ions with hexaniobates into the organic phase, as suggested by reactions (10) and (11), was probed by 23 Na NMR since this non-invasive method affords direct evidence of the presence of the targeted element in the sample. The 23 Na NMR spectra given in Fig.…”

“…While various polyoxoniobates can be isolated in the solid state or at a near-neutral pH, 8,9 the aqueous chemistry of Nb(V) in basic media (at pH ≥ 9) is dominated by the Lindqvist ions, i.e., H 21 Few aqueous hexatantalate and hexaniobate complexes with ruthenium have also been recently reported. 22,23 The unusually high alkalinity required to form and stabilize the hexaniobate and hexatantalate ions also prevent their interaction in aqueous solutions with other polyoxometalates, like those of tungsten and molybdenum, which only exist in acidic media. 24 This has limited the studies on hexaniobate (and hexatantalate) chemistry to a narrow pHrange and mainly to their interactions with alkali cations.…”

Assessing the Electrocatalytic Properties of the {Cp*RhIII}2+‐Polyoxometalate Derivative [H2PW11O39{RhIIICp*(OH2)}]3– towards CO2 Reduction

“…To move forward, we aimed at investigating the association of the POM properties with those of a known catalyst, preferably in more “classical” solvents like acetonitrile or even water. Numerous examples of organometallic derivatives of POMs were described in the literature . For example, some of us have discussed the reaction between [Ru(arene)Cl 2 ] 2 and the monovacant POM [PW 11 O 39 ] 7– and described the [PW 11 O 39 {Ru(arene)(H 2 O)}] 5– and [{PW 11 O 39 {Ru(arene)}} 2 {WO 2 }] 8– derivatives .…”

Coordination of {C5Me5Ir}2+ to [M6O19]8– (M = Nb, Ta) – Analogies and Differences between Rh and Ir, Nb and Ta

“…The coordination of noble metals to polyniobates (PONb) and polytantalates (POTa) has received much less attention. Following the pioneering work of Proust et al on the coordination of an organometallic {( p ‐cym)Ru} 2+ ( p ‐cym = p ‐cymene) moiety to [Nb 6 O 19 ] 8– ,12 we expanded this field by coordinating {Cp*Rh} 2+ fragments to both niobium and tantalum hexametalates [M 6 O 19 ] 8–[13] to synthesize the first Pt IV ‐containing hexaniobates14 and by isolating the first complexes of hexatantalate with {(C 6 H 6 )Ru} 2+ 15. The iridium‐coordinated polyniobates and tantalates can be regarded as close structural and functional models for IrO 2 nanoparticles supported on the surfaces of Ta 2 O 5 or Nb 2 O 5 , which are very active catalysts for photo‐ and electrocatalytic water splitting 5.…”