Sr5Sb2As crystallizes in the orthorhombic Pnma space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sb(1) and one As(1) atom to form a mixture of distorted edge, corner, and face-sharing SrSb4As square pyramids. In the second Sr site, Sr(2) is bonded in a 5-coordinate geometry to four equivalent Sb(1) and one As(1) atom. In the third Sr site, Sr(3) is bonded in a 5-coordinate geometry to three equivalent Sb(1) and two equivalent As(1) atoms. In the fourth Sr site, Sr(4) is bonded to four equivalent Sb(1) and one As(1) atom to form a mixture of distorted edge, corner, and face-sharing SrSb4As trigonal bipyramids. Sb(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Sr(4), and three equivalent Sr(3) atoms. As(1) is bonded to one Sr(1), one Sr(2), one Sr(4), and four equivalent Sr(3) atoms to form distorted edge-sharing AsSr7 pentagonal bipyramids.
Sr5Sb2As crystallizes in the orthorhombic Pnma space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sb(1) and one As(1) atom to form a mixture of distorted edge, corner, and face-sharing SrSb4As square pyramids. There are two shorter (3.42 Å) and two longer (3.45 Å) Sr(1)-Sb(1) bond lengths. The Sr(1)-As(1) bond length is 3.33 Å. In the second Sr site, Sr(2) is bonded in a 5-coordinate geometry to four equivalent Sb(1) and one As(1) atom. There are two shorter (3.52 Å) and two longer (3.56 Å) Sr(2)-Sb(1) bond lengths. The Sr(2)-As(1) bond length is 3.11 Å. In the third Sr site, Sr(3) is bonded in a 5-coordinate geometry to three equivalent Sb(1) and two equivalent As(1) atoms. There are a spread of Sr(3)-Sb(1) bond distances ranging from 3.54-3.93 Å. There is one shorter (3.12 Å) and one longer (3.32 Å) Sr(3)-As(1) bond length. In the fourth Sr site, Sr(4) is bonded to four equivalent Sb(1) and one As(1) atom to form a mixture of distorted edge, corner, and face-sharing SrSb4As trigonal bipyramids. There are two shorter (3.46 Å) and two longer (3.53 Å) Sr(4)-Sb(1) bond lengths. The Sr(4)-As(1) bond length is 3.15 Å. Sb(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Sr(4), and three equivalent Sr(3) atoms. As(1) is bonded to one Sr(1), one Sr(2), one Sr(4), and four equivalent Sr(3) atoms to form distorted edge-sharing AsSr7 pentagonal bipyramids.