SrNb5Se8 crystallizes in the monoclinic C2/m space group. Sr(1) is bonded in a 10-coordinate geometry to two equivalent Se(1), four equivalent Se(2), and four equivalent Se(3) atoms. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second Nb site, Nb(2) is bonded to one Se(1), two equivalent Se(2), and three equivalent Se(4) atoms to form a mixture of distorted edge, corner, and face-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. In the third Nb site, Nb(3) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form a mixture of distorted edge, corner, and face-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Sr(1), one Nb(2), one Nb(3), and two equivalent Nb(1) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Nb(1), and two equivalent Nb(2) atoms. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent Sr(1) and three equivalent Nb(3) atoms. In the fourth Se site, Se(4) is bonded to two equivalent Nb(3) and three equivalent Nb(2) atoms to form distorted edge-sharing SeNb5 trigonal bipyramids.
SrNb5Se8 crystallizes in the monoclinic C2/m space group. Sr(1) is bonded in a 10-coordinate geometry to two equivalent Se(1), four equivalent Se(2), and four equivalent Se(3) atoms. Both Sr(1)-Se(1) bond lengths are 3.48 Å. All Sr(1)-Se(2) bond lengths are 3.31 Å. All Sr(1)-Se(3) bond lengths are 3.22 Å. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles are 48°. Both Nb(1)-Se(2) bond lengths are 2.68 Å. All Nb(1)-Se(1) bond lengths are 2.65 Å. In the second Nb site, Nb(2) is bonded to one Se(1), two equivalent Se(2), and three equivalent Se(4) atoms to form a mixture of distorted edge, corner, and face-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. The Nb(2)-Se(1) bond length is 2.53 Å. Both Nb(2)-Se(2) bond lengths are 2.58 Å. There are two shorter (2.77 Å) and one longer (2.87 Å) Nb(2)-Se(4) bond length. In the third Nb site, Nb(3) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form a mixture of distorted edge, corner, and face-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. The Nb(3)-Se(1) bond length is 2.70 Å. Both Nb(3)-Se(4) bond lengths are 2.84 Å. There is one shorter (2.58 Å) and two longer (2.61 Å) Nb(3)-Se(3) bond lengths. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Sr(1), one Nb(2), one Nb(3), and two equivalent Nb(1) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Nb(1), and two equivalent Nb(2) atoms. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent Sr(1) and three equivalent Nb(3) atoms. In the fourth Se site, Se(4) is bonded to two equivalent Nb(3) and three equivalent Nb(2) atoms to form distorted edge-sharing SeNb5 trigonal bipyramids.