Sr₂MnSb₂: A new ternary transition metal zintl phase

A transition metal-containing Zintl phase, Sr₂MnSb₂, was prepared from a stoichiometric combination reaction of the elements in Sn flux, and its structure was determined by single-crystal X-ray diffraction methods. The compound crystallizes in the orthorhombic space group Pnma with a = 15.936(3) Å, b = 14.498(3) Å, c = 8.2646(17) Å, and Z = 12. The structure of Sr₂MnSb₂ is composed of corrugated layers of corner- and edge-shared MnSb₄ tetrahedra. The basic building unit of the layer is a [Mn₃Sb₆]^12- cluster composed of three edge-shared MnSb₄ tetrahedra. These trinuclear clusters share four Sb vertexes to form a layer with cavities. Sr²⁺ cations are located at the inter-and intralayer space. Magnetic susceptibility measurements indicate an effective magnetic moment of 4.85 μ_B, a value smaller than what would be expected from Mn²⁺ ions.