Na2Sr3As4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one As(1), one As(2), one As(4), and two equivalent As(3) atoms to form distorted corner-sharing NaAs5 square pyramids. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one As(1), one As(3), two equivalent As(2), and two equivalent As(4) atoms. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one As(4), two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the second Sr site, Sr(2) is bonded in a 6-coordinate geometry to one As(4), two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the third Sr site, Sr(3) is bonded in a 6-coordinate geometry to one As(2), one As(3), two equivalent As(1), and two equivalent As(4) atoms. There are four inequivalent As sites. In the first As site, As(4) is bonded in a 8-coordinate geometry to one Na(1), two equivalent Na(2), one Sr(1), one Sr(2), two equivalent Sr(3), and one As(3) atom. In the second As site, As(1) is bonded in a 9-coordinate geometry to one Na(1), one Na(2), two equivalent Sr(1), two equivalent Sr(2), two equivalent Sr(3), and one As(1) atom. In the third As site, As(2) is bonded in a 9-coordinate geometry to one Na(1), two equivalent Na(2), one Sr(3), two equivalent Sr(1), two equivalent Sr(2), and one As(2) atom. In the fourth As site, As(3) is bonded in a 9-coordinate geometry to one Na(2), two equivalent Na(1), one Sr(3), two equivalent Sr(1), two equivalent Sr(2), and one As(4) atom.
Na2Sr3As4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one As(1), one As(2), one As(4), and two equivalent As(3) atoms to form distorted corner-sharing NaAs5 square pyramids. The Na(1)-As(1) bond length is 3.36 Å. The Na(1)-As(2) bond length is 3.32 Å. The Na(1)-As(4) bond length is 2.93 Å. There is one shorter (3.05 Å) and one longer (3.09 Å) Na(1)-As(3) bond length. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one As(1), one As(3), two equivalent As(2), and two equivalent As(4) atoms. The Na(2)-As(1) bond length is 3.07 Å. The Na(2)-As(3) bond length is 3.20 Å. There is one shorter (3.04 Å) and one longer (3.05 Å) Na(2)-As(2) bond length. There is one shorter (3.06 Å) and one longer (3.22 Å) Na(2)-As(4) bond length. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one As(4), two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. The Sr(1)-As(4) bond length is 3.30 Å. There is one shorter (3.25 Å) and one longer (3.79 Å) Sr(1)-As(1) bond length. There is one shorter (3.22 Å) and one longer (3.24 Å) Sr(1)-As(2) bond length. There is one shorter (3.21 Å) and one longer (3.22 Å) Sr(1)-As(3) bond length. In the second Sr site, Sr(2) is bonded in a 6-coordinate geometry to one As(4), two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. The Sr(2)-As(4) bond length is 3.26 Å. There is one shorter (3.27 Å) and one longer (3.28 Å) Sr(2)-As(1) bond length. There is one shorter (3.24 Å) and one longer (3.79 Å) Sr(2)-As(2) bond length. There is one shorter (3.21 Å) and one longer (3.22 Å) Sr(2)-As(3) bond length. In the third Sr site, Sr(3) is bonded in a 6-coordinate geometry to one As(2), one As(3), two equivalent As(1), and two equivalent As(4) atoms. The Sr(3)-As(2) bond length is 3.07 Å. The Sr(3)-As(3) bond length is 3.20 Å. There is one shorter (3.11 Å) and one longer (3.14 Å) Sr(3)-As(1) bond length. There is one shorter (3.07 Å) and one longer (3.10 Å) Sr(3)-As(4) bond length. There are four inequivalent As sites. In the first As site, As(4) is bonded in a 8-coordinate geometry to one Na(1), two equivalent Na(2), one Sr(1), one Sr(2), two equivalent Sr(3), and one As(3) atom. The As(4)-As(3) bond length is 2.51 Å. In the second As site, As(1) is bonded in a 9-coordinate geometry to one Na(1), one Na(2), two equivalent Sr(1), two equivalent Sr(2), two equivalent Sr(3), and one As(1) atom. The As(1)-As(1) bond length is 2.58 Å. In the third As site, As(2) is bonded in a 9-coordinate geometry to one Na(1), two equivalent Na(2), one Sr(3), two equivalent Sr(1), two equivalent Sr(2), and one As(2) atom. The As(2)-As(2) bond length is 2.54 Å. In the fourth As site, As(3) is bonded in a 9-coordinate geometry to one Na(2), two equivalent Na(1), one Sr(3), two equivalent Sr(1), two equivalent Sr(2), and one As(4) atom.