Unpredicted but It Exists: Trigonal Sc(2)Ru with a Significant Metal–Metal Charge Transfer

[Image: see text] The Sc(2)Ru compound, obtained by high-temperature synthesis, was found to crystallize in a new trigonal hP45 structure type [space group P3̅m1; a = 9.3583(9) Å and c = 11.285(1) Å]: Ru@Sc(8) cubes, Ru@Sc(12) icosahedra, and uncommon Ru@Sc(10) sphenocoronae are the building blocks of a unique motif tiling the whole crystal space. According to density functional theory studies, Sc(2)Ru is a metallic compound characterized by multicenter interactions: a significant charge transfer occurs from Sc to Ru, indicating an unexpectedly strong ionic character of the interactions between the two transition metals. Energy calculations support our experimental results in terms of stability of this compound, contributing to the recurrent discussion on the limits of the high-throughput first-principles calculations for metallic materials design.