Formation and Conversion of Yellow Molybdophosphonate Complexes in Aqueous-Organic Media

Abstract

Abstract The reaction of Mo(VI) with PHO32− in acidic solution containing CH3COCH3 or CH3CN led to the formation of the previously unknown 15-molybdobis(phosphonate) complex. The addition of an excess of PHO32− caused 15-molybdobis(phosphonate) to transform into 16-molybdotetrakis(phosphonate) in the CH3COCH3–water system. In the CH3CN–water system, on the other hand, the spontaneous transformation of 15-molybdobis(phosphonate) into 12-molybdobis(phosphonate) occurred in the presence of an excess of PHO32− or at greater acidities; the latter complex was also formed in aqueous media. The yellow heteropolyanions underwent electrochemical reductions, yielding mixed-valence blue species.