Naked Clusters of 56 Tin Atoms in the Solid State

Isolated, gigantic tin clusters of 56 atoms are discovered in the ternary compound Ba16Na204Sn310 (cubic, F4̄3m, Z = 1, a = 25.2041(8) Å) made by direct fusion of the elements at 800 °C. The cluster,
made of four face-fused pentagonal dodecahedra, has 36 pentagonal faces and 90 edges, and resembles
a concave fullerene “dented” at four places. It is made of three- and four-bonded tin atoms and is “stuffed”
with four barium cations, [Ba4@Sn56]36-. This is the largest main group naked cluster in the solid state
besides the fullerenes. Also occurring in the structure are two other isolated clusters of tin, Sn16-n (n = 0,
1, 2, 3, or 4) and Sn8.