Na 2 Ga 7 : A Zintl-Wade Phase Related to "α-Tetragonal Boron".

NaGa crystallizes with the orthorhombic space group (no. 62; = 14.8580(6) Å, = 8.6766(6) Å, and = 11.6105(5) Å; = 8) and constitutes a filled variant of the LiBSi structure type. The crystal structure consists of a network of icosahedral Ga units with 12 exohedral bonds and four-bonded Ga atoms in which the Na atoms occupy the channels and cavities. The atomic arrangement is consistent with the Zintl [(4b)Ga] and Wade [(12b)Ga] electron counting approach. The compound forms peritectically from NaGa and the melt at 501 °C and does not show a homogeneity range. The band structure calculations predict semiconducting behavior consistent with the electron balance [Na][(Ga)][Ga]. Magnetic susceptibility measurements show that NaGa is diamagnetic.