Ca3Ni2(WO6)2 crystallizes in the monoclinic P2 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form distorted CaO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and edges with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-48°. In the second Ca site, Ca(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with two equivalent W(2)O6 octahedra, corners with four equivalent Ca(3)O6 octahedra, corners with four equivalent Ni(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra, and edges with two equivalent W(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-69°. In the third Ca site, Ca(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with four equivalent Ca(2)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and edges with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-69°. There are two inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form WO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and faces with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-41°. In the second W site, W(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form WO6 octahedra that share corners with two equivalent Ca(2)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and faces with two equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles are 37°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with four equivalent Ca(2)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra, and faces with two equivalent W(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-41°. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form distorted NiO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with four equivalent Ca(3)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra, and faces with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-49°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(3), one W(2), and one Ni(2) atom to form a mixture of distorted corner and edge-sharing OCa2NiW trigonal pyramids. In the second O site, O(2) is bonded in a T-shaped geometry to one Ca(1), one W(1), and one Ni(1) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Ca(2), one Ca(3), one W(2), and one Ni(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Ca(2), one W(1), and one Ni(1) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Ca(3), one W(1), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ca(1), one W(2), and one Ni(2) atom.
Ca3Ni2(WO6)2 crystallizes in the monoclinic P2 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form distorted CaO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and edges with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-48°. Both Ca(1)-O(1) bond lengths are 2.39 Å. Both Ca(1)-O(2) bond lengths are 2.30 Å. Both Ca(1)-O(6) bond lengths are 2.49 Å. In the second Ca site, Ca(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with two equivalent W(2)O6 octahedra, corners with four equivalent Ca(3)O6 octahedra, corners with four equivalent Ni(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra, and edges with two equivalent W(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-69°. Both Ca(2)-O(3) bond lengths are 2.41 Å. Both Ca(2)-O(4) bond lengths are 2.25 Å. Both Ca(2)-O(5) bond lengths are 2.47 Å. In the third Ca site, Ca(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with four equivalent Ca(2)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and edges with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-69°. Both Ca(3)-O(1) bond lengths are 2.39 Å. Both Ca(3)-O(3) bond lengths are 2.54 Å. Both Ca(3)-O(5) bond lengths are 2.32 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form WO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and faces with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-41°. Both W(1)-O(2) bond lengths are 1.92 Å. Both W(1)-O(4) bond lengths are 1.89 Å. Both W(1)-O(5) bond lengths are 2.08 Å. In the second W site, W(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form WO6 octahedra that share corners with two equivalent Ca(2)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and faces with two equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles are 37°. Both W(2)-O(1) bond lengths are 1.92 Å. Both W(2)-O(3) bond lengths are 2.03 Å. Both W(2)-O(6) bond lengths are 1.90 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with four equivalent Ca(2)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra, and faces with two equivalent W(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-41°. Both Ni(1)-O(2) bond lengths are 1.95 Å. Both Ni(1)-O(4) bond lengths are 2.15 Å. Both Ni(1)-O(5) bond lengths are 1.95 Å. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form distorted NiO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with four equivalent Ca(3)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra, and faces with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-49°. Both Ni(2)-O(1) bond lengths are 2.25 Å. Both Ni(2)-O(3) bond lengths are 1.96 Å. Both Ni(2)-O(6) bond lengths are 1.97 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(3), one W(2), and one Ni(2) atom to form a mixture of distorted corner and edge-sharing OCa2NiW trigonal pyramids. In the second O site, O(2) is bonded in a T-shaped geometry to one Ca(1), one W(1), and one Ni(1) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Ca(2), one Ca(3), one W(2), and one Ni(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Ca(2), one W(1), and one Ni(1) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Ca(3), one W(1), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ca(1), one W(2), and one Ni(2) atom.