Synthesis and Structure of Sr₂VN₃ and Ba₂VN₃, Two New Nitridovanadates

Two new ternary nitrides, Sr₂VN₃ and Ba₂VN₃, have been synthesized by the solid state reaction of Sr₂N or Ba₃N₂ with VN in sealed stainless steel crucibles and characterized by powder X-ray diffraction. Sr₂VN₃ crystallizes in the space group C2/c (a = 5.71036(9) Å, b= 10.9521(2) Å, c = 12.2881(2) Å, β = 90.986(1)°, Z = 8) and is isostructural with Sr₂TaN₃. Ba₂VN₃ crystallizes in the space group Cmca (α = 5.8614(4) Å, b = 11.4682(7) Å, c = 12.9121(9) Å, Z = 8) and is isostructural with Rb₂TiO₃. In each structure vanadium (V) is coordinated to nitrogen in distorted tetrahedra, forming infinite one-dimensional chains of [VN₃]^4_ units running parallel to a. The strontium and barium atoms in these A₂VN₃ materials (A = Sr, Ba) are coordinated to seven nitrogens. These materials are the first reported group II ternary nitrides to contain V⁵⁺.