Sr3CaSn16 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 13-coordinate geometry to one Sn(1), two equivalent Sn(3), two equivalent Sn(5), four equivalent Sn(7), and four equivalent Sn(9) atoms. In the second Sr site, Sr(2) is bonded in a 13-coordinate geometry to one Sn(1), one Sn(2), one Sn(3), one Sn(6), one Sn(7), two equivalent Sn(4), two equivalent Sn(5), two equivalent Sn(8), and two equivalent Sn(9) atoms. Ca(1) is bonded in a 13-coordinate geometry to one Sn(2), two equivalent Sn(3), two equivalent Sn(4), four equivalent Sn(6), and four equivalent Sn(8) atoms. There are nine inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 11-coordinate geometry to one Sr(1), two equivalent Sr(2), four equivalent Sn(4), and four equivalent Sn(9) atoms. In the second Sn site, Sn(2) is bonded in a 11-coordinate geometry to two equivalent Sr(2), one Ca(1), four equivalent Sn(5), and four equivalent Sn(8) atoms. In the third Sn site, Sn(3) is bonded in a 11-coordinate geometry to one Sr(1), one Sr(2), one Ca(1), two equivalent Sn(6), two equivalent Sn(7), two equivalent Sn(8), and two equivalent Sn(9) atoms. In the fourth Sn site, Sn(4) is bonded in a 9-coordinate geometry to two equivalent Sr(2), one Ca(1), one Sn(4), one Sn(9), two equivalent Sn(1), and two equivalent Sn(6) atoms. In the fifth Sn site, Sn(5) is bonded in a 9-coordinate geometry to one Sr(1), two equivalent Sr(2), one Sn(5), one Sn(8), two equivalent Sn(2), and two equivalent Sn(7) atoms. In the sixth Sn site, Sn(6) is bonded in a 9-coordinate geometry to one Sr(2), two equivalent Ca(1), one Sn(7), one Sn(8), two equivalent Sn(3), and two equivalent Sn(4) atoms. In the seventh Sn site, Sn(7) is bonded in a 9-coordinate geometry to one Sr(2), two equivalent Sr(1), one Sn(6), one Sn(9), two equivalent Sn(3), and two equivalent Sn(5) atoms. In the eighth Sn site, Sn(8) is bonded in a 4-coordinate geometry to two equivalent Sr(2), two equivalent Ca(1), one Sn(5), one Sn(6), two equivalent Sn(2), and two equivalent Sn(3) atoms. In the ninth Sn site, Sn(9) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Sn(4), one Sn(7), two equivalent Sn(1), and two equivalent Sn(3) atoms.
Sr3CaSn16 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 13-coordinate geometry to one Sn(1), two equivalent Sn(3), two equivalent Sn(5), four equivalent Sn(7), and four equivalent Sn(9) atoms. The Sr(1)-Sn(1) bond length is 3.51 Å. Both Sr(1)-Sn(3) bond lengths are 3.57 Å. Both Sr(1)-Sn(5) bond lengths are 3.66 Å. All Sr(1)-Sn(7) bond lengths are 3.47 Å. All Sr(1)-Sn(9) bond lengths are 3.54 Å. In the second Sr site, Sr(2) is bonded in a 13-coordinate geometry to one Sn(1), one Sn(2), one Sn(3), one Sn(6), one Sn(7), two equivalent Sn(4), two equivalent Sn(5), two equivalent Sn(8), and two equivalent Sn(9) atoms. The Sr(2)-Sn(1) bond length is 3.55 Å. The Sr(2)-Sn(2) bond length is 3.56 Å. The Sr(2)-Sn(3) bond length is 3.52 Å. The Sr(2)-Sn(6) bond length is 3.68 Å. The Sr(2)-Sn(7) bond length is 3.65 Å. Both Sr(2)-Sn(4) bond lengths are 3.48 Å. Both Sr(2)-Sn(5) bond lengths are 3.47 Å. Both Sr(2)-Sn(8) bond lengths are 3.57 Å. Both Sr(2)-Sn(9) bond lengths are 3.55 Å. Ca(1) is bonded in a 13-coordinate geometry to one Sn(2), two equivalent Sn(3), two equivalent Sn(4), four equivalent Sn(6), and four equivalent Sn(8) atoms. The Ca(1)-Sn(2) bond length is 3.49 Å. Both Ca(1)-Sn(3) bond lengths are 3.53 Å. Both Ca(1)-Sn(4) bond lengths are 3.63 Å. All Ca(1)-Sn(6) bond lengths are 3.44 Å. All Ca(1)-Sn(8) bond lengths are 3.52 Å. There are nine inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 11-coordinate geometry to one Sr(1), two equivalent Sr(2), four equivalent Sn(4), and four equivalent Sn(9) atoms. All Sn(1)-Sn(4) bond lengths are 3.36 Å. All Sn(1)-Sn(9) bond lengths are 3.35 Å. In the second Sn site, Sn(2) is bonded in a 11-coordinate geometry to two equivalent Sr(2), one Ca(1), four equivalent Sn(5), and four equivalent Sn(8) atoms. All Sn(2)-Sn(5) bond lengths are 3.37 Å. All Sn(2)-Sn(8) bond lengths are 3.34 Å. In the third Sn site, Sn(3) is bonded in a 11-coordinate geometry to one Sr(1), one Sr(2), one Ca(1), two equivalent Sn(6), two equivalent Sn(7), two equivalent Sn(8), and two equivalent Sn(9) atoms. Both Sn(3)-Sn(6) bond lengths are 3.35 Å. Both Sn(3)-Sn(7) bond lengths are 3.36 Å. Both Sn(3)-Sn(8) bond lengths are 3.34 Å. Both Sn(3)-Sn(9) bond lengths are 3.36 Å. In the fourth Sn site, Sn(4) is bonded in a 9-coordinate geometry to two equivalent Sr(2), one Ca(1), one Sn(4), one Sn(9), two equivalent Sn(1), and two equivalent Sn(6) atoms. The Sn(4)-Sn(4) bond length is 2.94 Å. The Sn(4)-Sn(9) bond length is 3.44 Å. Both Sn(4)-Sn(6) bond lengths are 3.08 Å. In the fifth Sn site, Sn(5) is bonded in a 9-coordinate geometry to one Sr(1), two equivalent Sr(2), one Sn(5), one Sn(8), two equivalent Sn(2), and two equivalent Sn(7) atoms. The Sn(5)-Sn(5) bond length is 2.96 Å. The Sn(5)-Sn(8) bond length is 3.44 Å. Both Sn(5)-Sn(7) bond lengths are 3.09 Å. In the sixth Sn site, Sn(6) is bonded in a 9-coordinate geometry to one Sr(2), two equivalent Ca(1), one Sn(7), one Sn(8), two equivalent Sn(3), and two equivalent Sn(4) atoms. The Sn(6)-Sn(7) bond length is 2.98 Å. The Sn(6)-Sn(8) bond length is 3.38 Å. In the seventh Sn site, Sn(7) is bonded in a 9-coordinate geometry to one Sr(2), two equivalent Sr(1), one Sn(6), one Sn(9), two equivalent Sn(3), and two equivalent Sn(5) atoms. The Sn(7)-Sn(9) bond length is 3.42 Å. In the eighth Sn site, Sn(8) is bonded in a 4-coordinate geometry to two equivalent Sr(2), two equivalent Ca(1), one Sn(5), one Sn(6), two equivalent Sn(2), and two equivalent Sn(3) atoms. In the ninth Sn site, Sn(9) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Sn(4), one Sn(7), two equivalent Sn(1), and two equivalent Sn(3) atoms.