Nd4FeCo3(AsO)4 crystallizes in the orthorhombic Pmm2 space group. There are three inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 4-coordinate geometry to two equivalent As(2), two equivalent As(3), one O(1), one O(2), and two equivalent O(3) atoms. In the second Nd site, Nd(2) is bonded in a 4-coordinate geometry to four equivalent As(1), two equivalent O(1), and two equivalent O(3) atoms. In the third Nd site, Nd(3) is bonded in a 4-coordinate geometry to four equivalent As(1), two equivalent O(2), and two equivalent O(3) atoms. Fe(1) is bonded to two equivalent As(1) and two equivalent As(2) atoms to form distorted FeAs4 tetrahedra that share corners with two equivalent Fe(1)As4 tetrahedra, corners with two equivalent Co(1)As4 tetrahedra, and edges with four equivalent Co(2)As4 tetrahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent As(1) and two equivalent As(3) atoms to form CoAs4 tetrahedra that share corners with two equivalent Fe(1)As4 tetrahedra, corners with two equivalent Co(1)As4 tetrahedra, and edges with four equivalent Co(2)As4 tetrahedra. In the second Co site, Co(2) is bonded to one As(2), one As(3), and two equivalent As(1) atoms to form distorted CoAs4 tetrahedra that share corners with four equivalent Co(2)As4 tetrahedra, edges with two equivalent Fe(1)As4 tetrahedra, and edges with two equivalent Co(1)As4 tetrahedra. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to two equivalent Nd(2), two equivalent Nd(3), one Fe(1), one Co(1), and two equivalent Co(2) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to four equivalent Nd(1), two equivalent Fe(1), and two equivalent Co(2) atoms. In the third As site, As(3) is bonded in a 8-coordinate geometry to four equivalent Nd(1), two equivalent Co(1), and two equivalent Co(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form a mixture of edge and corner-sharing ONd4 tetrahedra. In the second O site, O(2) is bonded to two equivalent Nd(1) and two equivalent Nd(3) atoms to form a mixture of edge and corner-sharing ONd4 tetrahedra. In the third O site, O(3) is bonded to one Nd(2), one Nd(3), and two equivalent Nd(1) atoms to form a mixture of edge and corner-sharing ONd4 tetrahedra.
Nd4FeCo3(AsO)4 crystallizes in the orthorhombic Pmm2 space group. There are three inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 4-coordinate geometry to two equivalent As(2), two equivalent As(3), one O(1), one O(2), and two equivalent O(3) atoms. Both Nd(1)-As(2) bond lengths are 3.30 Å. Both Nd(1)-As(3) bond lengths are 3.44 Å. The Nd(1)-O(1) bond length is 2.33 Å. The Nd(1)-O(2) bond length is 2.32 Å. Both Nd(1)-O(3) bond lengths are 2.33 Å. In the second Nd site, Nd(2) is bonded in a 4-coordinate geometry to four equivalent As(1), two equivalent O(1), and two equivalent O(3) atoms. All Nd(2)-As(1) bond lengths are 3.37 Å. Both Nd(2)-O(1) bond lengths are 2.33 Å. Both Nd(2)-O(3) bond lengths are 2.34 Å. In the third Nd site, Nd(3) is bonded in a 4-coordinate geometry to four equivalent As(1), two equivalent O(2), and two equivalent O(3) atoms. All Nd(3)-As(1) bond lengths are 3.31 Å. Both Nd(3)-O(2) bond lengths are 2.36 Å. Both Nd(3)-O(3) bond lengths are 2.33 Å. Fe(1) is bonded to two equivalent As(1) and two equivalent As(2) atoms to form distorted FeAs4 tetrahedra that share corners with two equivalent Fe(1)As4 tetrahedra, corners with two equivalent Co(1)As4 tetrahedra, and edges with four equivalent Co(2)As4 tetrahedra. Both Fe(1)-As(1) bond lengths are 2.54 Å. Both Fe(1)-As(2) bond lengths are 2.56 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent As(1) and two equivalent As(3) atoms to form CoAs4 tetrahedra that share corners with two equivalent Fe(1)As4 tetrahedra, corners with two equivalent Co(1)As4 tetrahedra, and edges with four equivalent Co(2)As4 tetrahedra. Both Co(1)-As(1) bond lengths are 2.46 Å. Both Co(1)-As(3) bond lengths are 2.40 Å. In the second Co site, Co(2) is bonded to one As(2), one As(3), and two equivalent As(1) atoms to form distorted CoAs4 tetrahedra that share corners with four equivalent Co(2)As4 tetrahedra, edges with two equivalent Fe(1)As4 tetrahedra, and edges with two equivalent Co(1)As4 tetrahedra. The Co(2)-As(2) bond length is 2.51 Å. The Co(2)-As(3) bond length is 2.45 Å. Both Co(2)-As(1) bond lengths are 2.51 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to two equivalent Nd(2), two equivalent Nd(3), one Fe(1), one Co(1), and two equivalent Co(2) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to four equivalent Nd(1), two equivalent Fe(1), and two equivalent Co(2) atoms. In the third As site, As(3) is bonded in a 8-coordinate geometry to four equivalent Nd(1), two equivalent Co(1), and two equivalent Co(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form a mixture of edge and corner-sharing ONd4 tetrahedra. In the second O site, O(2) is bonded to two equivalent Nd(1) and two equivalent Nd(3) atoms to form a mixture of edge and corner-sharing ONd4 tetrahedra. In the third O site, O(3) is bonded to one Nd(2), one Nd(3), and two equivalent Nd(1) atoms to form a mixture of edge and corner-sharing ONd4 tetrahedra.