Electronegativity and location of anionic ligands drive yttrium NMR for molecular, surface and solid-state structures

Abstract

Yttrium is present in various forms in molecular compounds and solid-state structures; it typically provides specific mechanical and optical properties. Hence, yttrium containing compounds are used in a broad range of applications such as catalysis, lasers and optical devices. Obtaining descriptors that can provide access to a detailed structure–property relationship would therefore be a strong base for the rational design of such applications. Towards this goal, ⁸⁹Y (100% abundant spin ½ nucleus), is associated with a broad range of NMR chemical shifts that greatly depend on the coordination environment of Y, rendering ⁸⁹Y NMR an attractive method for the characterization of yttrium containing compounds. However, to date, it has been difficult to obtain a direct relationship between ⁸⁹Y chemical shifts and its coordination environment. Here, we use computational chemistry to model the chemical shift of a broad range of Y(III) molecular compounds with the goal to reveal the underlying factors that determine the ⁸⁹Y chemical shift. We show through natural chemical shift (NCS)-analysis that isotropic chemical shifts can easily help to distinguish between different types of ligands solely based on the electronegativity of the central atom of the anionic ligands directly bound to Y(III). NCS-analysis further demonstrates that the second most important parameter is the degree of pyramidalization of the three anionic ligands imposed by additional neutral ligands. While isotropic chemical shifts can be similar due to compensating effects, investigation of the chemical shift anisotropy (CSA) enables discriminating between the coordination environment of Y.