Solvothermal Synthesis of [Cr(7)S(8)(en)(8)Cl(2)]Cl(3) ⋅ 2H(2)O with Magnetically Frustrated [Cr(7)S(8)](5+) Double‐Cubes

A novel transition metal chalcohalide [Cr(7)S(8)(en)(8)Cl(2)]Cl(3) ⋅ 2H(2)O, with [Cr(7)S(8)](5+) dicubane cationic clusters, has been synthesized by a low temperature solvothermal method, using dimethyl sulfoxide (DMSO) and ethylenediamine (en) solvents. Ethylenediamine ligand exhibits bi‐ and monodentate coordination modes; in the latter case ethylenediamine coordinates to Cr atoms of adjacent clusters, giving rise to a 2D polymeric structure. Although magnetic susceptibility shows no magnetic ordering down to 1.8 K, a highly negative Weiss constant, θ=−224(2) K, obtained from Curie‐Weiss fit of inverse susceptibility, suggests strong antiferromagnetic (AFM) interactions between S=3/2 Cr(III) centers. Due to the complexity of the system with (2S+1)(7)=16384 microstates from seven Cr(3+) centers, a simplified model with only two exchange constants was used for simulations. Density‐functional theory (DFT) calculations yielded the two exchange constants to be J (1)=−21.4 cm(−1) and J (2)=−30.2 cm(−1), confirming competing AFM coupling between the shared Cr(3+) center and the peripheral Cr(3+) ions of the dicubane cluster. The best simulation of the experimental data was obtained with J (1)=−20.0 cm(−1) and J (2)=−21.0 cm(−1), in agreement with the slightly stronger AFM exchange within the triangles of the peripheral Cr(3+) ions as compared to the AFM exchange between the central and peripheral Cr(3+) ions. This compound is proposed as a synthon towards magnetically frustrated systems assembled by linking dicubane transition metal‐chalcogenide clusters into polymeric networks.