Triheteropolyanions containing copper(II), manganese(II), or manganese(III)

Electrochemical Behaviour of First Row Transition Metal Substituted Polyoxotungstates: A Comparative Study in Acetonitrile

“…The solution of PW 11 Fe III in acetonitrile changed from yellow to purple and a band with the maximum at 536 nm appeared in the visible region spectrum (Figure 6), corresponding to the PW 11 Fe II anion. [10] For the PW 11 Mn III anion the characteristic bands of the Mn III O 6 chromophore, [17,53] at 493 and 524 nm (sh), disappeared during electrolyses and the electronic spectrum of the electrolysed solution showed only a charge-transfer band extending to the UV region, indicating a Mn II phore. [53,54] These results clearly show that the first reduction peak in the voltammograms of PW 11 [16,17,19] Nevertheless, the particular kinetic inertness of the Mn III / Mn II couple has been referred to for other Mn complexes.…”

“…[66] The potassium compounds of SiW 11 M (or SiW 11 ) were prepared by reported methods. [20,50,53,67] An aqueous solution of the potassium salt (0.5 mmol in 30 mL) and a solution of TBABr in 1,2-dichloroethane (4 mmol in 45 mL) were mixed and vigorously stirred. The organic phase was then collected and the 1,2-dichloroethane removed by evaporation.…”

A (Nitrido)chromium(V) Function Incorporated in a Keggin‐Type Polyoxometalate: [PW11O39CrN]5– – Synthesis, Characterization and Elements of Reactivity

“…The mechanism proposed for the intermetallic Ntransfer relies on three steps: (i) formation of a bimetallic µ-nitrido-bridged precursor, (ii) bielectronic transfer and (iii) dissociation of the resulting complex. [60][61][62] As Cr III is known to be inert, the first step could prove to be problematic in this case, [60] but we were also not successful in employing this route with the more labile Mn III centre in (tba) 4 [63] We conclude that, in order to favour the second step, more study of the electronic properties of the chosen POM systems will be required by analogy to previous studies on porphyrin systems. [64,65] Fortunately, we were more successful with the synthetic route devised by Bendix et al, [24] who showed that a variety of (nitrido)chromium complexes can be easily synthesized by the reaction of [CrCl 3 (thf) 3 ] with [(salen)MnN], which generates a source of the {CrN} 2+ function in situ, [66] and subsequent complexation with a polydentate ligand.…”

Spectroscopic Studies of Polyoxometalates and their Complexes with Lanthanide(III) Ions in Solution

“…Evaluation of the splitting of 7F0 -ι 5 D2 and 7F0 ; 5D1 excitation bands in Ln-ΡOM complexes indicates their low symmetry. Unsaturated polyanions such as SiW11O8 -39 exhibit a ligand field strength distinctly weaker than H2 O [30]. Furthermore, due to the weak nature of f -f f transitions, the sensitivity of absorption measurements are limited.…”