BaCo2(PO4)2 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(4), four equivalent O(1), and four equivalent O(2) atoms. Co(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form distorted CoO5 trigonal bipyramids that share corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Co(1)O5 trigonal bipyramids, and  an edgeedge with one P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Co(1)O5 trigonal bipyramids and  an edgeedge with one Co(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Ba(1), one Co(1), and one P(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Co(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Co(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ba(1), one Co(1), and one P(1) atom.
BaCo2(PO4)2 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(4), four equivalent O(1), and four equivalent O(2) atoms. Both Ba(1)-O(4) bond lengths are 2.81 Å. There are two shorter (2.80 Å) and two longer (3.09 Å) Ba(1)-O(1) bond lengths. There are two shorter (2.91 Å) and two longer (3.36 Å) Ba(1)-O(2) bond lengths. Co(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form distorted CoO5 trigonal bipyramids that share corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Co(1)O5 trigonal bipyramids, and  an edgeedge with one P(1)O4 tetrahedra. The Co(1)-O(1) bond length is 2.32 Å. The Co(1)-O(2) bond length is 1.98 Å. The Co(1)-O(4) bond length is 2.00 Å. There is one shorter (2.02 Å) and one longer (2.07 Å) Co(1)-O(3) bond length. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Co(1)O5 trigonal bipyramids and  an edgeedge with one Co(1)O5 trigonal bipyramid. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.58 Å. The P(1)-O(4) bond length is 1.54 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Ba(1), one Co(1), and one P(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Co(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Co(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ba(1), one Co(1), and one P(1) atom.