Comparative Spectroscopic and Electrochemical Study of V(V)-Substituted Keggin-Type Phosphomolybdates and -Tungstates

Vanadium-substituted Keggin-type heteropolyanions have been studied for a wide variety of applications, ranging from catalysis to antiviral/antimicrobial agents. While the V-substituted phosphomolybdates [PV_xMo_12−xO₄₀]^(3+x)− have been well investigated in this context, comparatively little is known about the corresponding phosphotungstates [PV_xW_12-xO₄₀]^(3+x)−. We have succeeded in synthesizing the sodium salts of the whole series [PV_xW_12−xO₄₀]^(3+x)−, for x = 1 to 6, and characterised them spectroscopically (FT-IR, UV-Vis, ³¹P-, and ⁵¹V-NMR) and electrochemically (CV and SWV). Thereby, direct comparisons between the vanadium-substituted phosphomolybdates and -tungstates, with substitution degrees from 1 to 6, can be established, which provides a solid basis for further investigations of potential applications.