Phosphine selenides: versatile NMR probes for analyzing hydrogen OH⋯Se and halogen I⋯Se bonds

Abstract

Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for studying the structure and dynamics of various non-covalent interactions. However, often spectral parameters that are applicable for estimation of parameters of one type of non-covalent interaction will be inapplicable for another. Therefore, researchers are compelled to use spectral parameters that are specifically tailored to the type of non-covalent interaction being studied. This complexity makes it difficult to compare different types of non-covalent interactions with each other and, consequently, to establish a strict unified classification for them. This pioneering study proposes to use phosphine selenides as universal probes for investigating hydrogen and halogen bonding in solution. The study was carried out using the example of triethylphosphine selenide Et₃PSe complexes with hydrogen bonds of Se⋯HO type and R₃PSe (where R: Me, Et, n-Bu, t-Bu and Ph) with halogen bonds of Se⋯X type (where X: I and Br) in solution. The presence of non-covalent interactions was confirmed experimentally by means of ¹H, ³¹P and ⁷⁷Se NMR, as well as by quantum chemical calculation methods (optimization: PW6B95-D3/def2-QZVP; NMR: B97-2/pcsSeg-2).