High-pressure synthesis and crystal structure of SrGa(4)As(4)

Strontium tetra­gallate(II,III) tetra­arsenide, SrGa(4)As(4), was synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 8 GPa and 1573 K. The com­pound crystallizes in a new structure type (P3(2)21, Z = 3) as a three-dimensional (3D) framework of corner-sharing SrAs(8) quadratic anti­prisms with strontium situated on a twofold rotation axis (Wyckoff position 3b). This arrangement is surrounded by a 3D framework which can be described as alternately stacked layers of either condensed Ga(III)As(4) tetra­hedra or honeycomb-like layers built up from distorted ethane-like Ga(II) (2)As(6) units com­prising Ga—Ga bonds.