Sr14(SnAs4)3 is Magnesium tetraboride-derived structured and crystallizes in the trigonal R3 space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one As(2), one As(4), two equivalent As(1), and two equivalent As(3) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one Sn(3), one As(3), one As(4), two equivalent As(1), and two equivalent As(2) atoms. In the third Sr site, Sr(3) is bonded in a 6-coordinate geometry to one As(1), one As(2), two equivalent As(3), and two equivalent As(4) atoms. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one Sn(1), one As(1), one As(3), two equivalent As(2), and two equivalent As(4) atoms. In the fifth Sr site, Sr(5) is bonded in a 7-coordinate geometry to one Sn(1), three equivalent As(3), and three equivalent As(4) atoms. In the sixth Sr site, Sr(6) is bonded in a 6-coordinate geometry to one Sn(3), three equivalent As(1), and three equivalent As(3) atoms. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a distorted body-centered cubic geometry to one Sr(5), three equivalent Sr(4), one Sn(2), and three equivalent As(4) atoms. In the second Sn site, Sn(2) is bonded in a 3-coordinate geometry to one Sn(1) and three equivalent As(2) atoms. In the third Sn site, Sn(3) is bonded in a 7-coordinate geometry to one Sr(6), three equivalent Sr(2), and three equivalent As(1) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to one Sr(3), one Sr(4), one Sr(6), two equivalent Sr(1), two equivalent Sr(2), and one Sn(3) atom. In the second As site, As(2) is bonded to one Sr(1), one Sr(3), two equivalent Sr(2), two equivalent Sr(4), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing AsSr6Sn pentagonal bipyramids. In the third As site, As(3) is bonded in a 8-coordinate geometry to one Sr(2), one Sr(4), one Sr(5), one Sr(6), two equivalent Sr(1), and two equivalent Sr(3) atoms. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(5), two equivalent Sr(3), two equivalent Sr(4), and one Sn(1) atom.
Sr14(SnAs4)3 is Magnesium tetraboride-derived structured and crystallizes in the trigonal R3 space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one As(2), one As(4), two equivalent As(1), and two equivalent As(3) atoms. The Sr(1)-As(2) bond length is 3.34 Å. The Sr(1)-As(4) bond length is 3.13 Å. There is one shorter (3.13 Å) and one longer (3.26 Å) Sr(1)-As(1) bond length. There is one shorter (3.16 Å) and one longer (3.58 Å) Sr(1)-As(3) bond length. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one Sn(3), one As(3), one As(4), two equivalent As(1), and two equivalent As(2) atoms. The Sr(2)-Sn(3) bond length is 3.69 Å. The Sr(2)-As(3) bond length is 3.14 Å. The Sr(2)-As(4) bond length is 3.61 Å. There is one shorter (3.39 Å) and one longer (3.55 Å) Sr(2)-As(1) bond length. There is one shorter (3.10 Å) and one longer (3.24 Å) Sr(2)-As(2) bond length. In the third Sr site, Sr(3) is bonded in a 6-coordinate geometry to one As(1), one As(2), two equivalent As(3), and two equivalent As(4) atoms. The Sr(3)-As(1) bond length is 3.33 Å. The Sr(3)-As(2) bond length is 3.09 Å. There is one shorter (3.18 Å) and one longer (3.37 Å) Sr(3)-As(3) bond length. There is one shorter (3.24 Å) and one longer (3.57 Å) Sr(3)-As(4) bond length. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one Sn(1), one As(1), one As(3), two equivalent As(2), and two equivalent As(4) atoms. The Sr(4)-Sn(1) bond length is 3.41 Å. The Sr(4)-As(1) bond length is 3.18 Å. The Sr(4)-As(3) bond length is 3.23 Å. There is one shorter (3.34 Å) and one longer (3.45 Å) Sr(4)-As(2) bond length. There is one shorter (3.20 Å) and one longer (3.47 Å) Sr(4)-As(4) bond length. In the fifth Sr site, Sr(5) is bonded in a 7-coordinate geometry to one Sn(1), three equivalent As(3), and three equivalent As(4) atoms. The Sr(5)-Sn(1) bond length is 3.25 Å. All Sr(5)-As(3) bond lengths are 3.25 Å. All Sr(5)-As(4) bond lengths are 3.32 Å. In the sixth Sr site, Sr(6) is bonded in a 6-coordinate geometry to one Sn(3), three equivalent As(1), and three equivalent As(3) atoms. The Sr(6)-Sn(3) bond length is 3.62 Å. All Sr(6)-As(1) bond lengths are 3.49 Å. All Sr(6)-As(3) bond lengths are 3.13 Å. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a distorted body-centered cubic geometry to one Sr(5), three equivalent Sr(4), one Sn(2), and three equivalent As(4) atoms. The Sn(1)-Sn(2) bond length is 2.85 Å. All Sn(1)-As(4) bond lengths are 2.66 Å. In the second Sn site, Sn(2) is bonded in a 3-coordinate geometry to one Sn(1) and three equivalent As(2) atoms. All Sn(2)-As(2) bond lengths are 2.63 Å. In the third Sn site, Sn(3) is bonded in a 7-coordinate geometry to one Sr(6), three equivalent Sr(2), and three equivalent As(1) atoms. All Sn(3)-As(1) bond lengths are 2.77 Å. There are four inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to one Sr(3), one Sr(4), one Sr(6), two equivalent Sr(1), two equivalent Sr(2), and one Sn(3) atom. In the second As site, As(2) is bonded to one Sr(1), one Sr(3), two equivalent Sr(2), two equivalent Sr(4), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing AsSr6Sn pentagonal bipyramids. In the third As site, As(3) is bonded in a 8-coordinate geometry to one Sr(2), one Sr(4), one Sr(5), one Sr(6), two equivalent Sr(1), and two equivalent Sr(3) atoms. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to one Sr(1), one Sr(2), one Sr(5), two equivalent Sr(3), two equivalent Sr(4), and one Sn(1) atom.