Sr2Co(SeO3)3 crystallizes in the triclinic P-1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), one O(7), and two equivalent O(9) atoms. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(6), two equivalent O(7), and two equivalent O(8) atoms. Co(1) is bonded in a distorted octahedral geometry to one O(1), one O(2), one O(4), one O(5), one O(8), and one O(9) atom. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(2), and one O(3) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(4), one O(5), and one O(6) atom. In the third Se site, Se(3) is bonded in a distorted trigonal non-coplanar geometry to one O(7), one O(8), and one O(9) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Sr(1), one Co(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Co(1), and one Se(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(2), one Co(1), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one Co(1), and one Se(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Sr(1), one Sr(2), and one Se(2) atom. In the seventh O site, O(7) is bonded to one Sr(1), two equivalent Sr(2), and one Se(3) atom to form distorted OSr3Se tetrahedra that share  a cornercorner with one O(9)Sr2CoSe tetrahedra,  an edgeedge with one O(9)Sr2CoSe tetrahedra, and  an edgeedge with one O(7)Sr3Se tetrahedra. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Co(1), and one Se(3) atom. In the ninth O site, O(9) is bonded to two equivalent Sr(1), one Co(1), and one Se(3) atom to form distorted OSr2CoSe tetrahedra that share  a cornercorner with one O(7)Sr3Se tetrahedra,  an edgeedge with one O(9)Sr2CoSe tetrahedra, and  an edgeedge with one O(7)Sr3Se tetrahedra.
Sr2Co(SeO3)3 crystallizes in the triclinic P-1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), one O(7), and two equivalent O(9) atoms. The Sr(1)-O(1) bond length is 2.58 Å. The Sr(1)-O(2) bond length is 3.02 Å. The Sr(1)-O(3) bond length is 2.59 Å. The Sr(1)-O(5) bond length is 2.60 Å. The Sr(1)-O(6) bond length is 2.56 Å. The Sr(1)-O(7) bond length is 2.72 Å. Both Sr(1)-O(9) bond lengths are 2.72 Å. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(6), two equivalent O(7), and two equivalent O(8) atoms. The Sr(2)-O(2) bond length is 2.72 Å. The Sr(2)-O(3) bond length is 2.64 Å. The Sr(2)-O(4) bond length is 2.60 Å. The Sr(2)-O(6) bond length is 2.54 Å. There is one shorter (2.67 Å) and one longer (2.75 Å) Sr(2)-O(7) bond length. There is one shorter (2.66 Å) and one longer (2.93 Å) Sr(2)-O(8) bond length. Co(1) is bonded in a distorted octahedral geometry to one O(1), one O(2), one O(4), one O(5), one O(8), and one O(9) atom. The Co(1)-O(1) bond length is 2.13 Å. The Co(1)-O(2) bond length is 2.10 Å. The Co(1)-O(4) bond length is 2.09 Å. The Co(1)-O(5) bond length is 2.07 Å. The Co(1)-O(8) bond length is 2.33 Å. The Co(1)-O(9) bond length is 2.15 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(2), and one O(3) atom. The Se(1)-O(1) bond length is 1.73 Å. The Se(1)-O(2) bond length is 1.76 Å. The Se(1)-O(3) bond length is 1.72 Å. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(4), one O(5), and one O(6) atom. The Se(2)-O(4) bond length is 1.73 Å. The Se(2)-O(5) bond length is 1.74 Å. The Se(2)-O(6) bond length is 1.71 Å. In the third Se site, Se(3) is bonded in a distorted trigonal non-coplanar geometry to one O(7), one O(8), and one O(9) atom. The Se(3)-O(7) bond length is 1.73 Å. The Se(3)-O(8) bond length is 1.73 Å. The Se(3)-O(9) bond length is 1.74 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Sr(1), one Co(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Co(1), and one Se(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(2), one Co(1), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one Co(1), and one Se(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Sr(1), one Sr(2), and one Se(2) atom. In the seventh O site, O(7) is bonded to one Sr(1), two equivalent Sr(2), and one Se(3) atom to form distorted OSr3Se tetrahedra that share  a cornercorner with one O(9)Sr2CoSe tetrahedra,  an edgeedge with one O(9)Sr2CoSe tetrahedra, and  an edgeedge with one O(7)Sr3Se tetrahedra. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Co(1), and one Se(3) atom. In the ninth O site, O(9) is bonded to two equivalent Sr(1), one Co(1), and one Se(3) atom to form distorted OSr2CoSe tetrahedra that share  a cornercorner with one O(7)Sr3Se tetrahedra,  an edgeedge with one O(9)Sr2CoSe tetrahedra, and  an edgeedge with one O(7)Sr3Se tetrahedra.