Matere bond identification in non-crystalline materials by using X-ray photoelectron spectroscopy

The Re atoms in perrhenate salts can act as electrophiles and form, with nucleophiles, adducts assembled via Re⋯O interactions. X-ray photoelectron spectroscopy (XPS) is proven here as a reliable technique to identify the presence of such interactions (commonly named matere bonds, MaBs) in powders. Specifically, ten hybrid organic-inorganic perrhenate salts are described and their single crystal X-ray (XRD) analyses allowed for establishing that short σ-hole Re⋯O MaBs were present in seven of them. The Re 4f7/2 photoelectron energy is smaller in these systems than in those wherein the interaction is absent. This signal is thus a valuable tool to identify the MaB presence in non-crystalline samples, namely XPS complements single crystal X-ray analyses in determining the MaB presence.