Na₅Sn₁₃: A New Zintl Phase with a Complex Network Structure Constructed from Tin Pentagons

The compound Na5Sn13 forms in the sodium−tin system in high yield following prolonged reaction of a quenched mixture at 280 °C in a Ta container. The compound exhibits a complex three-dimensional structure (29 independent atoms) built mainly of 4-bonded tin atoms in interbonded pentagons (orthorhombic, space group Cmcm (No. 63); a = 8.979(1) Å, b = 19.448(6) Å, c = 50.43(2) Å, Z = 16). According to Zintl−Klemm electron-counting formalisms, the compound has a closed-shell electronic configuration with the number of 3-bonded Sn- equal to the number of sodium cations. Property measurements show that the compound is diamagnetic.