Abstract Solvent-free copper(I) and thallium(I) compounds of the general formula [M₂[B₁₀H₁₀]] have been synthesized. The compounds have been identified by IR spectroscopy and X-ray diffraction. According to X-ray diffraction data, the structures of both compounds are three-dimensional frameworks. In copper(I) complex [Cu₂[B₁₀H₁₀]]_n, the formation of three-center M–H–B bonds is observed. In thallium(I) compound Tl₂[B₁₀H₁₀], the bond between cations and anions is ionic, which is confirmed by IR spectroscopy data. The Hirschfeld surface analysis of the boron cluster anion was performed for both compounds to identify and analyze intramolecular interactions.