A reaction between ReI 3 and KCN at elevated temperature led to the formation of the new cyanometalate cluster anion [{Re 4 (μ 3 -CCN) 4 }(CN) 12 ] 8− (1). The anion contains μ 3 -CCN 3− ligands, which are stabilized by the coordination to the triangular faces of the tetrahedral {Re 4 } metallocluster in a μ 3 mode. The compound crystallized as a potassium salt, and its crystal structure was determined by single-crystal X-ray diffraction analysis. It was shown that μ 3 -CCN 3− ligands are ambidentate and can interact with transition-metal cations similarly to terminal CN groups, resulting in the polymer framework formation.