| Summary: | <p>Two novel chromium oxide arsenide materials have been synthesized, Sr<sub>2</sub>CrO<sub>2</sub>Cr<sub>2</sub>OAs<sub>2</sub> (i.e., Sr<sub>2</sub>Cr<sub>3</sub>As<sub>2</sub>O<sub>3</sub>) and Sr<sub>2</sub>CrO<sub>3</sub>CrAs (i.e., Sr<sub>2</sub>Cr<sub>2</sub>AsO<sub>3</sub>), both of which contain chromium ions in two distinct layers. Sr<sub>2</sub>CrO<sub>2</sub>Cr<sub>2</sub>OAs<sub>2</sub> was targeted following electron microscopy measurements on a related phase. It crystallizes in the space group <em>P</em>4/<em>mmm</em> and accommodates distorted CrO<sub>4</sub>As<sub>2</sub> octahedra containing Cr<sup>2+</sup> and distorted CrO<sub>2</sub>As<sub>4</sub> octahedra containing Cr<sup>3+</sup>. In contrast, Sr<sub>2</sub>CrO<sub>3</sub>CrAs incorporates Cr<sup>3+</sup> in CrO<sub>5</sub> square-pyramidal coordination in [Sr<sub>2</sub>CrO<sub>3</sub>]<sup>+</sup> layers and Cr<sup>2+</sup> ions in CrAs<sub>4</sub> tetrahedra in [CrAs]<sup>−</sup> layers and crystallizes in the space group <em>P</em>4/<em>nmm</em>. Powder neutron diffraction data reveal antiferromagnetic ordering in both compounds. In Sr<sub>2</sub>CrO<sub>3</sub>CrAs the Cr<sup>2+</sup> moments in the [CrAs]<sup>−</sup> layers exhibit long-range ordering, while the Cr<sup>3+</sup> moments in the [Sr<sub>2</sub>CrO<sub>3</sub>]<sup>+</sup> layers only exhibit short-range ordering. However, in Sr<sub>2</sub>CrO<sub>2</sub>Cr<sub>2</sub>OAs<sub>2</sub>, both the Cr<sup>2+</sup> moments in the CrO<sub>4</sub>As<sub>2</sub> environments and the Cr<sup>3+</sup> moments in the CrO<sub>2</sub>As<sub>4</sub> polyhedra are long-range-ordered below 530(10) K. Above this temperature, only the Cr<sup>3+</sup> moments are ordered with a Néel temperature slightly in excess of 600 K. A subtle structural change is evident in Sr<sub>2</sub>CrO<sub>2</sub>Cr<sub>2</sub>OAs<sub>2</sub> below the magnetic ordering transitions.</p>
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