Nd15B6C20 crystallizes in the triclinic P-1 space group. There are eight inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 9-coordinate geometry to one B(2), one C(1), one C(4), two equivalent C(2), two equivalent C(5), and two equivalent C(8) atoms. In the second Nd site, Nd(2) is bonded in a 9-coordinate geometry to one B(1), one B(3), one C(1), one C(10), one C(4), one C(6), one C(9), and two equivalent C(7) atoms. In the third Nd site, Nd(3) is bonded in a 8-coordinate geometry to one B(2), one C(1), one C(10), one C(6), one C(8), one C(9), and two equivalent C(3) atoms. In the fourth Nd site, Nd(4) is bonded in a 5-coordinate geometry to one C(1), one C(10), one C(3), one C(7), and one C(9) atom. In the fifth Nd site, Nd(5) is bonded in a 9-coordinate geometry to one B(1), one B(2), one C(2), one C(5), one C(6), two equivalent C(4), and two equivalent C(8) atoms. In the sixth Nd site, Nd(6) is bonded to one C(3), one C(7), one C(9), and two equivalent C(1) atoms to form a mixture of distorted corner and edge-sharing NdC5 square pyramids. In the seventh Nd site, Nd(7) is bonded in a 10-coordinate geometry to two equivalent B(1), two equivalent B(3), two equivalent C(2), two equivalent C(4), and two equivalent C(5) atoms. In the eighth Nd site, Nd(8) is bonded to one C(3), one C(7), one C(9), and two equivalent C(10) atoms to form a mixture of distorted corner and edge-sharing NdC5 square pyramids. There are three inequivalent B sites. In the first B site, B(1) is bonded in a bent 150 degrees geometry to one Nd(2), one Nd(5), one Nd(7), one C(2), and one C(9) atom. In the second B site, B(2) is bonded in a bent 150 degrees geometry to one Nd(1), one Nd(3), one Nd(5), one C(3), and one C(8) atom. In the third B site, B(3) is bonded in a distorted bent 150 degrees geometry to one Nd(2), one Nd(7), one C(5), and one C(7) atom. There are ten inequivalent C sites. In the first C site, C(1) is bonded to one Nd(1), one Nd(2), one Nd(3), one Nd(4), and two equivalent Nd(6) atoms to form CNd6 octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  an edgeedge with one C(10)Nd5C octahedra,  an edgeedge with one C(1)Nd6 octahedra, edges with two equivalent C(3)Nd5B octahedra, edges with two equivalent C(7)Nd5B octahedra, and edges with two equivalent C(9)Nd5B octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the second C site, C(2) is bonded in a 1-coordinate geometry to one Nd(5), one Nd(7), two equivalent Nd(1), and one B(1) atom. In the third C site, C(3) is bonded to one Nd(4), one Nd(6), one Nd(8), two equivalent Nd(3), and one B(2) atom to form distorted CNd5B octahedra that share  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  a cornercorner with one C(1)Nd6 octahedra,  an edgeedge with one C(3)Nd5B octahedra,  an edgeedge with one C(7)Nd5B octahedra, edges with two equivalent C(9)Nd5B octahedra, edges with two equivalent C(10)Nd5C octahedra, and edges with two equivalent C(1)Nd6 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the fourth C site, C(4) is bonded in a 5-coordinate geometry to one Nd(1), one Nd(2), one Nd(7), two equivalent Nd(5), and one C(6) atom. In the fifth C site, C(5) is bonded in a 1-coordinate geometry to one Nd(5), one Nd(7), two equivalent Nd(1), and one B(3) atom. In the sixth C site, C(6) is bonded in a 5-coordinate geometry to one Nd(2), one Nd(3), one Nd(5), one C(10), and one C(4) atom. In the seventh C site, C(7) is bonded to one Nd(4), one Nd(6), one Nd(8), two equivalent Nd(2), and one B(3) atom to form distorted CNd5B octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  a cornercorner with one C(1)Nd6 octahedra,  an edgeedge with one C(3)Nd5B octahedra,  an edgeedge with one C(7)Nd5B octahedra, edges with two equivalent C(9)Nd5B octahedra, edges with two equivalent C(10)Nd5C octahedra, and edges with two equivalent C(1)Nd6 octahedra. The corner-sharing octahedral tilt angles range from 1-8°. In the eighth C site, C(8) is bonded in a 1-coordinate geometry to one Nd(3), two equivalent Nd(1), two equivalent Nd(5), and one B(2) atom. In the ninth C site, C(9) is bonded to one Nd(2), one Nd(3), one Nd(4), one Nd(6), one Nd(8), and one B(1) atom to form distorted CNd5B octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  a cornercorner with one C(1)Nd6 octahedra, edges with two equivalent C(3)Nd5B octahedra, edges with two equivalent C(7)Nd5B octahedra, edges with two equivalent C(10)Nd5C octahedra, and edges with two equivalent C(1)Nd6 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the tenth C site, C(10) is bonded to one Nd(2), one Nd(3), one Nd(4), two equivalent Nd(8), and one C(6) atom to form CNd5C octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(1)Nd6 octahedra,  an edgeedge with one C(10)Nd5C octahedra,  an edgeedge with one C(1)Nd6 octahedra, edges with two equivalent C(3)Nd5B octahedra, edges with two equivalent C(7)Nd5B octahedra, and edges with two equivalent C(9)Nd5B octahedra. The corner-sharing octahedral tilt angles range from 3-8°.
Nd15B6C20 crystallizes in the triclinic P-1 space group. There are eight inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 9-coordinate geometry to one B(2), one C(1), one C(4), two equivalent C(2), two equivalent C(5), and two equivalent C(8) atoms. The Nd(1)-B(2) bond length is 3.19 Å. The Nd(1)-C(1) bond length is 2.56 Å. The Nd(1)-C(4) bond length is 2.76 Å. There is one shorter (2.76 Å) and one longer (3.08 Å) Nd(1)-C(2) bond length. There is one shorter (2.81 Å) and one longer (2.89 Å) Nd(1)-C(5) bond length. There is one shorter (2.75 Å) and one longer (2.86 Å) Nd(1)-C(8) bond length. In the second Nd site, Nd(2) is bonded in a 9-coordinate geometry to one B(1), one B(3), one C(1), one C(10), one C(4), one C(6), one C(9), and two equivalent C(7) atoms. The Nd(2)-B(1) bond length is 2.81 Å. The Nd(2)-B(3) bond length is 3.13 Å. The Nd(2)-C(1) bond length is 2.65 Å. The Nd(2)-C(10) bond length is 2.70 Å. The Nd(2)-C(4) bond length is 2.98 Å. The Nd(2)-C(6) bond length is 2.66 Å. The Nd(2)-C(9) bond length is 2.68 Å. There is one shorter (2.45 Å) and one longer (2.73 Å) Nd(2)-C(7) bond length. In the third Nd site, Nd(3) is bonded in a 8-coordinate geometry to one B(2), one C(1), one C(10), one C(6), one C(8), one C(9), and two equivalent C(3) atoms. The Nd(3)-B(2) bond length is 2.83 Å. The Nd(3)-C(1) bond length is 2.59 Å. The Nd(3)-C(10) bond length is 2.71 Å. The Nd(3)-C(6) bond length is 2.76 Å. The Nd(3)-C(8) bond length is 3.12 Å. The Nd(3)-C(9) bond length is 2.72 Å. There is one shorter (2.51 Å) and one longer (2.66 Å) Nd(3)-C(3) bond length. In the fourth Nd site, Nd(4) is bonded in a 5-coordinate geometry to one C(1), one C(10), one C(3), one C(7), and one C(9) atom. The Nd(4)-C(1) bond length is 2.56 Å. The Nd(4)-C(10) bond length is 2.74 Å. The Nd(4)-C(3) bond length is 2.69 Å. The Nd(4)-C(7) bond length is 2.64 Å. The Nd(4)-C(9) bond length is 2.45 Å. In the fifth Nd site, Nd(5) is bonded in a 9-coordinate geometry to one B(1), one B(2), one C(2), one C(5), one C(6), two equivalent C(4), and two equivalent C(8) atoms. The Nd(5)-B(1) bond length is 2.80 Å. The Nd(5)-B(2) bond length is 2.95 Å. The Nd(5)-C(2) bond length is 2.69 Å. The Nd(5)-C(5) bond length is 2.88 Å. The Nd(5)-C(6) bond length is 2.83 Å. There is one shorter (2.69 Å) and one longer (2.73 Å) Nd(5)-C(4) bond length. There is one shorter (2.74 Å) and one longer (2.79 Å) Nd(5)-C(8) bond length. In the sixth Nd site, Nd(6) is bonded to one C(3), one C(7), one C(9), and two equivalent C(1) atoms to form a mixture of distorted corner and edge-sharing NdC5 square pyramids. The Nd(6)-C(3) bond length is 2.69 Å. The Nd(6)-C(7) bond length is 2.65 Å. The Nd(6)-C(9) bond length is 2.65 Å. There is one shorter (2.64 Å) and one longer (2.65 Å) Nd(6)-C(1) bond length. In the seventh Nd site, Nd(7) is bonded in a 10-coordinate geometry to two equivalent B(1), two equivalent B(3), two equivalent C(2), two equivalent C(4), and two equivalent C(5) atoms. Both Nd(7)-B(1) bond lengths are 2.95 Å. Both Nd(7)-B(3) bond lengths are 2.73 Å. Both Nd(7)-C(2) bond lengths are 2.68 Å. Both Nd(7)-C(4) bond lengths are 2.92 Å. Both Nd(7)-C(5) bond lengths are 2.67 Å. In the eighth Nd site, Nd(8) is bonded to one C(3), one C(7), one C(9), and two equivalent C(10) atoms to form a mixture of distorted corner and edge-sharing NdC5 square pyramids. The Nd(8)-C(3) bond length is 2.63 Å. The Nd(8)-C(7) bond length is 2.63 Å. The Nd(8)-C(9) bond length is 2.65 Å. There is one shorter (2.57 Å) and one longer (2.68 Å) Nd(8)-C(10) bond length. There are three inequivalent B sites. In the first B site, B(1) is bonded in a bent 150 degrees geometry to one Nd(2), one Nd(5), one Nd(7), one C(2), and one C(9) atom. The B(1)-C(2) bond length is 1.48 Å. The B(1)-C(9) bond length is 1.47 Å. In the second B site, B(2) is bonded in a bent 150 degrees geometry to one Nd(1), one Nd(3), one Nd(5), one C(3), and one C(8) atom. The B(2)-C(3) bond length is 1.47 Å. The B(2)-C(8) bond length is 1.48 Å. In the third B site, B(3) is bonded in a distorted bent 150 degrees geometry to one Nd(2), one Nd(7), one C(5), and one C(7) atom. The B(3)-C(5) bond length is 1.48 Å. The B(3)-C(7) bond length is 1.46 Å. There are ten inequivalent C sites. In the first C site, C(1) is bonded to one Nd(1), one Nd(2), one Nd(3), one Nd(4), and two equivalent Nd(6) atoms to form CNd6 octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  an edgeedge with one C(10)Nd5C octahedra,  an edgeedge with one C(1)Nd6 octahedra, edges with two equivalent C(3)Nd5B octahedra, edges with two equivalent C(7)Nd5B octahedra, and edges with two equivalent C(9)Nd5B octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the second C site, C(2) is bonded in a 1-coordinate geometry to one Nd(5), one Nd(7), two equivalent Nd(1), and one B(1) atom. In the third C site, C(3) is bonded to one Nd(4), one Nd(6), one Nd(8), two equivalent Nd(3), and one B(2) atom to form distorted CNd5B octahedra that share  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  a cornercorner with one C(1)Nd6 octahedra,  an edgeedge with one C(3)Nd5B octahedra,  an edgeedge with one C(7)Nd5B octahedra, edges with two equivalent C(9)Nd5B octahedra, edges with two equivalent C(10)Nd5C octahedra, and edges with two equivalent C(1)Nd6 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the fourth C site, C(4) is bonded in a 5-coordinate geometry to one Nd(1), one Nd(2), one Nd(7), two equivalent Nd(5), and one C(6) atom. The C(4)-C(6) bond length is 1.37 Å. In the fifth C site, C(5) is bonded in a 1-coordinate geometry to one Nd(5), one Nd(7), two equivalent Nd(1), and one B(3) atom. In the sixth C site, C(6) is bonded in a 5-coordinate geometry to one Nd(2), one Nd(3), one Nd(5), one C(10), and one C(4) atom. The C(6)-C(10) bond length is 1.34 Å. In the seventh C site, C(7) is bonded to one Nd(4), one Nd(6), one Nd(8), two equivalent Nd(2), and one B(3) atom to form distorted CNd5B octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  a cornercorner with one C(1)Nd6 octahedra,  an edgeedge with one C(3)Nd5B octahedra,  an edgeedge with one C(7)Nd5B octahedra, edges with two equivalent C(9)Nd5B octahedra, edges with two equivalent C(10)Nd5C octahedra, and edges with two equivalent C(1)Nd6 octahedra. The corner-sharing octahedral tilt angles range from 1-8°. In the eighth C site, C(8) is bonded in a 1-coordinate geometry to one Nd(3), two equivalent Nd(1), two equivalent Nd(5), and one B(2) atom. In the ninth C site, C(9) is bonded to one Nd(2), one Nd(3), one Nd(4), one Nd(6), one Nd(8), and one B(1) atom to form distorted CNd5B octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(10)Nd5C octahedra,  a cornercorner with one C(1)Nd6 octahedra, edges with two equivalent C(3)Nd5B octahedra, edges with two equivalent C(7)Nd5B octahedra, edges with two equivalent C(10)Nd5C octahedra, and edges with two equivalent C(1)Nd6 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the tenth C site, C(10) is bonded to one Nd(2), one Nd(3), one Nd(4), two equivalent Nd(8), and one C(6) atom to form CNd5C octahedra that share  a cornercorner with one C(3)Nd5B octahedra,  a cornercorner with one C(7)Nd5B octahedra,  a cornercorner with one C(9)Nd5B octahedra,  a cornercorner with one C(1)Nd6 octahedra,  an edgeedge with one C(10)Nd5C octahedra,  an edgeedge with one C(1)Nd6 octahedra, edges with two equivalent C(3)Nd5B octahedra, edges with two equivalent C(7)Nd5B octahedra, and edges with two equivalent C(9)Nd5B octahedra. The corner-sharing octahedral tilt angles range from 3-8°.