Molybdenum magnetic shielding and quadrupolar tensors for a series of molybdate salts: a solid-state 95Mo NMR study

Abstract

A series of molybdate, MoO₄^2–, salts have been studied using solid-state ⁹⁵Mo NMR spectroscopy at applied magnetic field strengths of 11.75, 17.63 and 21.14 T. In contrast to previous investigations, the principal components of the Mo shielding and EFG tensors have been obtained, as well as their relative orientations. At the fields employed, the anisotropic Mo shielding and quadrupolar interactions make significant contributions to the observed ⁹⁵Mo central transition NMR lineshapes. Based on available structural data, the extent of distortion of the MoO₄^2– anion from T_d symmetry is reflected in the observed ⁹⁵Mo nuclear quadrupolar coupling constants for the molybdate salts with divalent cations (i.e., Ca²⁺, Sr²⁺, Cd²⁺, Ba²⁺, Pb²⁺), but no correlation is found for molybdate salts containing the monovalent alkali metal (Li⁺, K⁺, Rb⁺, Cs⁺) cations.