Na2CoP2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(12), one O(3), one O(4), one O(5), one O(7), and one O(9) atom to form distorted NaO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(10), one O(11), one O(3), one O(4), one O(6), and one O(8) atom to form distorted NaO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. In the third Na site, Na(3) is bonded in a 6-coordinate geometry to one O(13), one O(3), one O(8), one O(9), and two equivalent O(5) atoms. In the fourth Na site, Na(4) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(4), one O(7), and two equivalent O(6) atoms. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded in a square co-planar geometry to two equivalent O(10) and two equivalent O(11) atoms. In the second Co site, Co(2) is bonded in a square co-planar geometry to two equivalent O(13) and two equivalent O(8) atoms. In the third Co site, Co(3) is bonded in a square co-planar geometry to two equivalent O(12) and two equivalent O(9) atoms. In the fourth Co site, Co(4) is bonded in a square co-planar geometry to two equivalent O(14) and two equivalent O(7) atoms. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(11), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra, and  an edgeedge with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second P site, P(2) is bonded to one O(12), one O(2), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and  an edgeedge with one Na(2)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the third P site, P(3) is bonded to one O(13), one O(2), one O(3), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Na(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-60°. In the fourth P site, P(4) is bonded to one O(1), one O(10), one O(14), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-60°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(4) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one P(2) and one P(3) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(3), and one P(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(4), and one P(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(3), and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(4), and one P(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(4), one Co(4), and one P(1) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Co(2), and one P(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one Co(3), and one P(3) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one Co(1), and one P(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Na(2), one Co(1), and one P(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Na(1), one Co(3), and one P(2) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Na(3), one Co(2), and one P(3) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Na(4), one Co(4), and one P(4) atom.
Na2CoP2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(12), one O(3), one O(4), one O(5), one O(7), and one O(9) atom to form distorted NaO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The Na(1)-O(12) bond length is 2.39 Å. The Na(1)-O(3) bond length is 2.38 Å. The Na(1)-O(4) bond length is 2.33 Å. The Na(1)-O(5) bond length is 2.62 Å. The Na(1)-O(7) bond length is 2.65 Å. The Na(1)-O(9) bond length is 2.42 Å. In the second Na site, Na(2) is bonded to one O(10), one O(11), one O(3), one O(4), one O(6), and one O(8) atom to form distorted NaO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The Na(2)-O(10) bond length is 2.42 Å. The Na(2)-O(11) bond length is 2.39 Å. The Na(2)-O(3) bond length is 2.34 Å. The Na(2)-O(4) bond length is 2.38 Å. The Na(2)-O(6) bond length is 2.62 Å. The Na(2)-O(8) bond length is 2.66 Å. In the third Na site, Na(3) is bonded in a 6-coordinate geometry to one O(13), one O(3), one O(8), one O(9), and two equivalent O(5) atoms. The Na(3)-O(13) bond length is 2.38 Å. The Na(3)-O(3) bond length is 2.61 Å. The Na(3)-O(8) bond length is 2.43 Å. The Na(3)-O(9) bond length is 2.66 Å. There is one shorter (2.34 Å) and one longer (2.37 Å) Na(3)-O(5) bond length. In the fourth Na site, Na(4) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(4), one O(7), and two equivalent O(6) atoms. The Na(4)-O(10) bond length is 2.66 Å. The Na(4)-O(14) bond length is 2.38 Å. The Na(4)-O(4) bond length is 2.61 Å. The Na(4)-O(7) bond length is 2.42 Å. There is one shorter (2.34 Å) and one longer (2.37 Å) Na(4)-O(6) bond length. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded in a square co-planar geometry to two equivalent O(10) and two equivalent O(11) atoms. Both Co(1)-O(10) bond lengths are 2.03 Å. Both Co(1)-O(11) bond lengths are 1.97 Å. In the second Co site, Co(2) is bonded in a square co-planar geometry to two equivalent O(13) and two equivalent O(8) atoms. Both Co(2)-O(13) bond lengths are 1.97 Å. Both Co(2)-O(8) bond lengths are 2.03 Å. In the third Co site, Co(3) is bonded in a square co-planar geometry to two equivalent O(12) and two equivalent O(9) atoms. Both Co(3)-O(12) bond lengths are 1.97 Å. Both Co(3)-O(9) bond lengths are 2.03 Å. In the fourth Co site, Co(4) is bonded in a square co-planar geometry to two equivalent O(14) and two equivalent O(7) atoms. Both Co(4)-O(14) bond lengths are 1.97 Å. Both Co(4)-O(7) bond lengths are 2.03 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(11), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra, and  an edgeedge with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. The P(1)-O(1) bond length is 1.63 Å. The P(1)-O(11) bond length is 1.54 Å. The P(1)-O(5) bond length is 1.51 Å. The P(1)-O(7) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(12), one O(2), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and  an edgeedge with one Na(2)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. The P(2)-O(12) bond length is 1.55 Å. The P(2)-O(2) bond length is 1.64 Å. The P(2)-O(6) bond length is 1.51 Å. The P(2)-O(8) bond length is 1.56 Å. In the third P site, P(3) is bonded to one O(13), one O(2), one O(3), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Na(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-60°. The P(3)-O(13) bond length is 1.54 Å. The P(3)-O(2) bond length is 1.64 Å. The P(3)-O(3) bond length is 1.51 Å. The P(3)-O(9) bond length is 1.56 Å. In the fourth P site, P(4) is bonded to one O(1), one O(10), one O(14), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-60°. The P(4)-O(1) bond length is 1.63 Å. The P(4)-O(10) bond length is 1.55 Å. The P(4)-O(14) bond length is 1.54 Å. The P(4)-O(4) bond length is 1.51 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(4) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one P(2) and one P(3) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(3), and one P(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(4), and one P(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(3), and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(4), and one P(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(4), one Co(4), and one P(1) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Co(2), and one P(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one Co(3), and one P(3) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one Co(1), and one P(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Na(2), one Co(1), and one P(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Na(1), one Co(3), and one P(2) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Na(3), one Co(2), and one P(3) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Na(4), one Co(4), and one P(4) atom.