Structure of a heteropoly blue. The four-electron reduced .beta.-12-molybdophosphate anion

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

“…Given that orthophosphate MB methods are generally performed at pH < 1, it can be expected that PMB(4e À ) will almost always be present as [H 4 PMo 12 O 40 ] 3À , with the possibility of [H 3 PMo 12 O 40 ] 4À existing at very low acid concentrations. This assignment is confirmed by the spectra of electrochemically formed PMB(4e À ) [42], characterisation of pure PMB(4e À ) at pH 1 [86], and ion-pair HPLC [56]. These two highly protonated forms of PMB(4e À ) are amongst the most intensely absorbing of any PMB species, with virtually identical absorptivities at their respective wavelength maxima (Fig.…”

DFT Calculations of the 183W NMR Chemical Shifts in Reduced Polyoxotungstates

“…some bonds are elongated). [15,[27][28][29][30] Thus, in all cases, for both the parent oxidized POM and its reduced counterparts, the structures used were the optimized ones before and after the two electrons had been introduced. This anion is a derivative of the Lindqvist anion that contains one tungsten atom in the formal oxidation state 2+ with an NO group in place of the terminal oxygen atom.…”

Redox chemistry of the Keggin heteropolyoxotungstate anion in ionic liquids

“…O40 ] nÀ species are prone to rearrangement[7,35], other electrochemically active Keggin isomers can contribute to the voltammetric response. By conducting our measurements under N 2 in an anaerobic enclosure and with dry, purified solvents and electrolytes, we have essentially eliminated additional complications from the effects of protonation.…”