Multicomponent Polyanions. 35. A 31P NMR Study of Aqueous Molybdophosphates.

Abstract

Equil. in the H+-MoO42--HPO42- system [25�, 3 M NaClO4] was studied by 31P NMR spectroscopy. In accordance with earlier studies L. Lyhamn, L. Petterson, 1980) for -log[H+] .gtorsim.5.5 or Mo:P <2.5 a single series of pentamolybdodiphosphate complexes, (H+)p(MoO42-)5(HPO42-)2 (p = 8, 9, 10) is formed. For Mo:P �4 and -log[H+] �4.3 the formation of 2 molybdophosphates with different Mo:P quotients was established. Thus NMR data are in contradiction to the original emf model, which predicts a homonuclear series of (H+)p(MoO42-)9(HPO42-)1 species, and supports the findings from the combined potentiometric-spectrophotometric study.