Nb2P4O15 crystallizes in the triclinic P1 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(13), one O(16), one O(19), one O(25), and one O(30) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(7)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. In the second Nb site, Nb(2) is bonded to one O(10), one O(15), one O(2), one O(20), one O(22), and one O(5) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra, and  a cornercorner with one P(6)O4 tetrahedra. In the third Nb site, Nb(3) is bonded to one O(12), one O(17), one O(26), one O(29), one O(3), and one O(6) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(7)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. In the fourth Nb site, Nb(4) is bonded to one O(18), one O(23), one O(28), one O(4), one O(7), and one O(9) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. There are eight inequivalent P sites. In the first P site, P(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 18-28°. In the second P site, P(2) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-35°. In the third P site, P(3) is bonded to one O(11), one O(12), one O(13), and one O(14) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-37°. In the fourth P site, P(4) is bonded to one O(14), one O(15), one O(16), and one O(17) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 5-24°. In the fifth P site, P(5) is bonded to one O(18), one O(19), one O(20), and one O(21) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, and  a cornercorner with one P(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 23-34°. In the sixth P site, P(6) is bonded to one O(21), one O(22), one O(23), and one O(24) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one P(5)O4 tetrahedra, and  a cornercorner with one P(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 27-34°. In the seventh P site, P(7) is bonded to one O(24), one O(25), one O(26), and one O(27) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one P(6)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 23-37°. In the eighth P site, P(8) is bonded to one O(27), one O(28), one O(29), and one O(30) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, and  a cornercorner with one P(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 11-26°. There are thirty inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Nb(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Nb(2) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Nb(3) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Nb(4) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(2) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one P(2) and one P(3) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(3) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one P(3) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one P(3) and one P(4) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one Nb(2) and one P(4) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Nb(1) and one P(4) atom. In the seventeenth O site, O(17) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(4) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(5) atom. In the nineteenth O site, O(19) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(5) atom. In the twentieth O site, O(20) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(5) atom. In the twenty-first O site, O(21) is bonded in a bent 150 degrees geometry to one P(5) and one P(6) atom. In the twenty-second O site, O(22) is bonded in a distorted bent 150 degrees geometry to one Nb(2) and one P(6) atom. In the twenty-third O site, O(23) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(6) atom. In the twenty-fourth O site, O(24) is bonded in a linear geometry to one P(6) and one P(7) atom. In the twenty-fifth O site, O(25) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(7) atom. In the twenty-sixth O site, O(26) is bonded in a distorted bent 150 degrees geometry to one Nb(3) and one P(7) atom. In the twenty-seventh O site, O(27) is bonded in a bent 150 degrees geometry to one P(7) and one P(8) atom. In the twenty-eighth O site, O(28) is bonded in a linear geometry to one Nb(4) and one P(8) atom. In the twenty-ninth O site, O(29) is bonded in a linear geometry to one Nb(3) and one P(8) atom. In the thirtieth O site, O(30) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(8) atom.
Nb2P4O15 crystallizes in the triclinic P1 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(13), one O(16), one O(19), one O(25), and one O(30) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(7)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. The Nb(1)-O(1) bond length is 1.73 Å. The Nb(1)-O(13) bond length is 2.35 Å. The Nb(1)-O(16) bond length is 2.03 Å. The Nb(1)-O(19) bond length is 2.04 Å. The Nb(1)-O(25) bond length is 2.07 Å. The Nb(1)-O(30) bond length is 2.07 Å. In the second Nb site, Nb(2) is bonded to one O(10), one O(15), one O(2), one O(20), one O(22), and one O(5) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra, and  a cornercorner with one P(6)O4 tetrahedra. The Nb(2)-O(10) bond length is 2.07 Å. The Nb(2)-O(15) bond length is 2.06 Å. The Nb(2)-O(2) bond length is 1.73 Å. The Nb(2)-O(20) bond length is 2.05 Å. The Nb(2)-O(22) bond length is 2.30 Å. The Nb(2)-O(5) bond length is 2.06 Å. In the third Nb site, Nb(3) is bonded to one O(12), one O(17), one O(26), one O(29), one O(3), and one O(6) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(7)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. The Nb(3)-O(12) bond length is 2.07 Å. The Nb(3)-O(17) bond length is 2.07 Å. The Nb(3)-O(26) bond length is 2.35 Å. The Nb(3)-O(29) bond length is 2.03 Å. The Nb(3)-O(3) bond length is 1.73 Å. The Nb(3)-O(6) bond length is 2.04 Å. In the fourth Nb site, Nb(4) is bonded to one O(18), one O(23), one O(28), one O(4), one O(7), and one O(9) atom to form distorted NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. The Nb(4)-O(18) bond length is 2.06 Å. The Nb(4)-O(23) bond length is 2.07 Å. The Nb(4)-O(28) bond length is 2.06 Å. The Nb(4)-O(4) bond length is 1.73 Å. The Nb(4)-O(7) bond length is 2.04 Å. The Nb(4)-O(9) bond length is 2.30 Å. There are eight inequivalent P sites. In the first P site, P(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 18-28°. The P(1)-O(5) bond length is 1.52 Å. The P(1)-O(6) bond length is 1.52 Å. The P(1)-O(7) bond length is 1.53 Å. The P(1)-O(8) bond length is 1.60 Å. In the second P site, P(2) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-35°. The P(2)-O(10) bond length is 1.53 Å. The P(2)-O(11) bond length is 1.58 Å. The P(2)-O(8) bond length is 1.59 Å. The P(2)-O(9) bond length is 1.48 Å. In the third P site, P(3) is bonded to one O(11), one O(12), one O(13), and one O(14) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-37°. The P(3)-O(11) bond length is 1.58 Å. The P(3)-O(12) bond length is 1.53 Å. The P(3)-O(13) bond length is 1.48 Å. The P(3)-O(14) bond length is 1.60 Å. In the fourth P site, P(4) is bonded to one O(14), one O(15), one O(16), and one O(17) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 5-24°. The P(4)-O(14) bond length is 1.60 Å. The P(4)-O(15) bond length is 1.52 Å. The P(4)-O(16) bond length is 1.53 Å. The P(4)-O(17) bond length is 1.52 Å. In the fifth P site, P(5) is bonded to one O(18), one O(19), one O(20), and one O(21) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, and  a cornercorner with one P(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 23-34°. The P(5)-O(18) bond length is 1.52 Å. The P(5)-O(19) bond length is 1.53 Å. The P(5)-O(20) bond length is 1.53 Å. The P(5)-O(21) bond length is 1.60 Å. In the sixth P site, P(6) is bonded to one O(21), one O(22), one O(23), and one O(24) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one P(5)O4 tetrahedra, and  a cornercorner with one P(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 27-34°. The P(6)-O(21) bond length is 1.59 Å. The P(6)-O(22) bond length is 1.48 Å. The P(6)-O(23) bond length is 1.52 Å. The P(6)-O(24) bond length is 1.58 Å. In the seventh P site, P(7) is bonded to one O(24), one O(25), one O(26), and one O(27) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one P(6)O4 tetrahedra, and  a cornercorner with one P(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 23-37°. The P(7)-O(24) bond length is 1.58 Å. The P(7)-O(25) bond length is 1.53 Å. The P(7)-O(26) bond length is 1.48 Å. The P(7)-O(27) bond length is 1.60 Å. In the eighth P site, P(8) is bonded to one O(27), one O(28), one O(29), and one O(30) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, and  a cornercorner with one P(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 11-26°. The P(8)-O(27) bond length is 1.60 Å. The P(8)-O(28) bond length is 1.52 Å. The P(8)-O(29) bond length is 1.53 Å. The P(8)-O(30) bond length is 1.52 Å. There are thirty inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Nb(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Nb(2) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Nb(3) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Nb(4) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(2) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one P(2) and one P(3) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(3) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one P(3) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one P(3) and one P(4) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one Nb(2) and one P(4) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Nb(1) and one P(4) atom. In the seventeenth O site, O(17) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(4) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(5) atom. In the nineteenth O site, O(19) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(5) atom. In the twentieth O site, O(20) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(5) atom. In the twenty-first O site, O(21) is bonded in a bent 150 degrees geometry to one P(5) and one P(6) atom. In the twenty-second O site, O(22) is bonded in a distorted bent 150 degrees geometry to one Nb(2) and one P(6) atom. In the twenty-third O site, O(23) is bonded in a bent 150 degrees geometry to one Nb(4) and one P(6) atom. In the twenty-fourth O site, O(24) is bonded in a linear geometry to one P(6) and one P(7) atom. In the twenty-fifth O site, O(25) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(7) atom. In the twenty-sixth O site, O(26) is bonded in a distorted bent 150 degrees geometry to one Nb(3) and one P(7) atom. In the twenty-seventh O site, O(27) is bonded in a bent 150 degrees geometry to one P(7) and one P(8) atom. In the twenty-eighth O site, O(28) is bonded in a linear geometry to one Nb(4) and one P(8) atom. In the twenty-ninth O site, O(29) is bonded in a linear geometry to one Nb(3) and one P(8) atom. In the thirtieth O site, O(30) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(8) atom.