Sr11Cd6Sb12: a new Zint1 compound with infinite chains of pentagonal tubes

A new Cd-containing transition metal Zintl phase, Sr₁₁Cd₆Sb₁₂, was obtained from a direct element combination reaction using the Sn flux method. Its structure was determined using single-crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/m with a=32.903(3) Å, b=4.7666(5) Å, c=12.6057(13) Å, β=109.752(2)°, and Z=2. Sr₁₁Cd₆Sb₁₂ has a one-dimensional infinite chain structure consisting of double pentagonal tubes, where Sr²⁺ cations reside both within two tubes and between the infinite chains of tubes. The anionic framework [Cd₆Sb₁₂]²²⁻ has features similar to those of Eu₁₀Mn₆Sb₁₃. The difference in Eu₁₀Mn₆Sb₁₃ is that its double pentagonal tubes are further condensed to form two-dimensional layers.