Sr3As4 crystallizes in the triclinic P1 space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one As(1), one As(2), one As(3), one As(4), one As(5), one As(8), and two equivalent As(6) atoms. In the second Sr site, Sr(2) is bonded to one As(1), one As(2), one As(3), one As(4), one As(6), one As(7), and two equivalent As(5) atoms to form a mixture of corner and edge-sharing SrAs8 hexagonal bipyramids. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one As(1), one As(2), one As(3), one As(4), one As(5), one As(8), and two equivalent As(7) atoms. In the fourth Sr site, Sr(4) is bonded to one As(1), one As(2), one As(3), one As(4), one As(6), one As(7), and two equivalent As(8) atoms to form a mixture of corner and edge-sharing SrAs8 hexagonal bipyramids. In the fifth Sr site, Sr(5) is bonded in a 8-coordinate geometry to one As(5), one As(6), one As(7), one As(8), two equivalent As(1), and two equivalent As(2) atoms. In the sixth Sr site, Sr(6) is bonded in a 8-coordinate geometry to one As(5), one As(6), one As(7), one As(8), two equivalent As(3), and two equivalent As(4) atoms. There are eight inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(5), one As(2), and one As(6) atom. In the second As site, As(2) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(5), one As(1), and one As(5) atom. In the third As site, As(3) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(6), one As(4), and one As(7) atom. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(6), one As(3), and one As(8) atom. In the fifth As site, As(5) is bonded in a 7-coordinate geometry to one Sr(1), one Sr(3), one Sr(5), one Sr(6), two equivalent Sr(2), and one As(2) atom. In the sixth As site, As(6) is bonded in a 7-coordinate geometry to one Sr(2), one Sr(4), one Sr(5), one Sr(6), two equivalent Sr(1), and one As(1) atom. In the seventh As site, As(7) is bonded in a 7-coordinate geometry to one Sr(2), one Sr(4), one Sr(5), one Sr(6), two equivalent Sr(3), and one As(3) atom. In the eighth As site, As(8) is bonded in a 7-coordinate geometry to one Sr(1), one Sr(3), one Sr(5), one Sr(6), two equivalent Sr(4), and one As(4) atom.
Sr3As4 crystallizes in the triclinic P1 space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one As(1), one As(2), one As(3), one As(4), one As(5), one As(8), and two equivalent As(6) atoms. The Sr(1)-As(1) bond length is 3.20 Å. The Sr(1)-As(2) bond length is 3.21 Å. The Sr(1)-As(3) bond length is 3.33 Å. The Sr(1)-As(4) bond length is 3.30 Å. The Sr(1)-As(5) bond length is 3.12 Å. The Sr(1)-As(8) bond length is 3.31 Å. There is one shorter (3.23 Å) and one longer (3.33 Å) Sr(1)-As(6) bond length. In the second Sr site, Sr(2) is bonded to one As(1), one As(2), one As(3), one As(4), one As(6), one As(7), and two equivalent As(5) atoms to form a mixture of corner and edge-sharing SrAs8 hexagonal bipyramids. The Sr(2)-As(1) bond length is 3.29 Å. The Sr(2)-As(2) bond length is 3.21 Å. The Sr(2)-As(3) bond length is 3.26 Å. The Sr(2)-As(4) bond length is 3.28 Å. The Sr(2)-As(6) bond length is 3.21 Å. The Sr(2)-As(7) bond length is 3.25 Å. There is one shorter (3.25 Å) and one longer (3.35 Å) Sr(2)-As(5) bond length. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one As(1), one As(2), one As(3), one As(4), one As(5), one As(8), and two equivalent As(7) atoms. The Sr(3)-As(1) bond length is 3.20 Å. The Sr(3)-As(2) bond length is 3.31 Å. The Sr(3)-As(3) bond length is 3.20 Å. The Sr(3)-As(4) bond length is 3.35 Å. The Sr(3)-As(5) bond length is 3.26 Å. The Sr(3)-As(8) bond length is 3.23 Å. There is one shorter (3.24 Å) and one longer (3.33 Å) Sr(3)-As(7) bond length. In the fourth Sr site, Sr(4) is bonded to one As(1), one As(2), one As(3), one As(4), one As(6), one As(7), and two equivalent As(8) atoms to form a mixture of corner and edge-sharing SrAs8 hexagonal bipyramids. The Sr(4)-As(1) bond length is 3.36 Å. The Sr(4)-As(2) bond length is 3.29 Å. The Sr(4)-As(3) bond length is 3.28 Å. The Sr(4)-As(4) bond length is 3.24 Å. The Sr(4)-As(6) bond length is 3.26 Å. The Sr(4)-As(7) bond length is 3.12 Å. There is one shorter (3.27 Å) and one longer (3.33 Å) Sr(4)-As(8) bond length. In the fifth Sr site, Sr(5) is bonded in a 8-coordinate geometry to one As(5), one As(6), one As(7), one As(8), two equivalent As(1), and two equivalent As(2) atoms. The Sr(5)-As(5) bond length is 3.11 Å. The Sr(5)-As(6) bond length is 3.24 Å. The Sr(5)-As(7) bond length is 3.37 Å. The Sr(5)-As(8) bond length is 3.33 Å. There is one shorter (3.29 Å) and one longer (3.32 Å) Sr(5)-As(1) bond length. There is one shorter (3.25 Å) and one longer (3.34 Å) Sr(5)-As(2) bond length. In the sixth Sr site, Sr(6) is bonded in a 8-coordinate geometry to one As(5), one As(6), one As(7), one As(8), two equivalent As(3), and two equivalent As(4) atoms. The Sr(6)-As(5) bond length is 3.32 Å. The Sr(6)-As(6) bond length is 3.35 Å. The Sr(6)-As(7) bond length is 3.15 Å. The Sr(6)-As(8) bond length is 3.17 Å. There is one shorter (3.27 Å) and one longer (3.31 Å) Sr(6)-As(3) bond length. There is one shorter (3.26 Å) and one longer (3.30 Å) Sr(6)-As(4) bond length. There are eight inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(5), one As(2), and one As(6) atom. The As(1)-As(2) bond length is 2.66 Å. The As(1)-As(6) bond length is 2.55 Å. In the second As site, As(2) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(5), one As(1), and one As(5) atom. The As(2)-As(5) bond length is 2.50 Å. In the third As site, As(3) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(6), one As(4), and one As(7) atom. The As(3)-As(4) bond length is 2.57 Å. The As(3)-As(7) bond length is 2.52 Å. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), two equivalent Sr(6), one As(3), and one As(8) atom. The As(4)-As(8) bond length is 2.52 Å. In the fifth As site, As(5) is bonded in a 7-coordinate geometry to one Sr(1), one Sr(3), one Sr(5), one Sr(6), two equivalent Sr(2), and one As(2) atom. In the sixth As site, As(6) is bonded in a 7-coordinate geometry to one Sr(2), one Sr(4), one Sr(5), one Sr(6), two equivalent Sr(1), and one As(1) atom. In the seventh As site, As(7) is bonded in a 7-coordinate geometry to one Sr(2), one Sr(4), one Sr(5), one Sr(6), two equivalent Sr(3), and one As(3) atom. In the eighth As site, As(8) is bonded in a 7-coordinate geometry to one Sr(1), one Sr(3), one Sr(5), one Sr(6), two equivalent Sr(4), and one As(4) atom.