Zr8Ni21 crystallizes in the triclinic P-1 space group. There are four inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a 13-coordinate geometry to one Ni(1), one Ni(11), one Ni(2), one Ni(4), one Ni(5), one Ni(6), one Ni(8), two equivalent Ni(10), two equivalent Ni(3), and two equivalent Ni(9) atoms. In the second Zr site, Zr(2) is bonded in a 10-coordinate geometry to one Ni(2), one Ni(3), one Ni(4), one Ni(6), one Ni(8), one Ni(9), two equivalent Ni(5), and two equivalent Ni(7) atoms. In the third Zr site, Zr(3) is bonded in a 12-coordinate geometry to one Ni(10), one Ni(5), one Ni(7), one Ni(8), two equivalent Ni(11), two equivalent Ni(2), two equivalent Ni(4), and two equivalent Ni(6) atoms. In the fourth Zr site, Zr(4) is bonded in a 12-coordinate geometry to one Ni(1), one Ni(10), one Ni(11), one Ni(2), one Ni(5), one Ni(6), one Ni(7), one Ni(9), two equivalent Ni(3), and two equivalent Ni(8) atoms. There are eleven inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Zr(1), two equivalent Zr(4), two equivalent Ni(10), two equivalent Ni(11), two equivalent Ni(2), and two equivalent Ni(6) atoms to form face-sharing NiZr4Ni8 cuboctahedra. In the second Ni site, Ni(2) is bonded to one Zr(1), one Zr(2), one Zr(4), two equivalent Zr(3), one Ni(1), one Ni(10), one Ni(11), one Ni(3), one Ni(4), one Ni(6), and one Ni(8) atom to form distorted NiZr5Ni7 cuboctahedra that share  a cornercorner with one Ni(2)Zr5Ni7 cuboctahedra,  an edgeedge with one Ni(2)Zr5Ni7 cuboctahedra,  a faceface with one Ni(1)Zr4Ni8 cuboctahedra, and faces with three equivalent Ni(6)Zr5Ni7 cuboctahedra. In the third Ni site, Ni(3) is bonded in a 5-coordinate geometry to one Zr(2), two equivalent Zr(1), two equivalent Zr(4), one Ni(2), one Ni(5), and two equivalent Ni(8) atoms. In the fourth Ni site, Ni(4) is bonded in a 10-coordinate geometry to one Zr(1), one Zr(2), two equivalent Zr(3), one Ni(11), one Ni(2), one Ni(5), one Ni(7), one Ni(8), and one Ni(9) atom. In the fifth Ni site, Ni(5) is bonded in a 12-coordinate geometry to one Zr(1), one Zr(3), one Zr(4), two equivalent Zr(2), one Ni(10), one Ni(11), one Ni(3), one Ni(4), one Ni(6), one Ni(7), and one Ni(9) atom. In the sixth Ni site, Ni(6) is bonded to one Zr(1), one Zr(2), one Zr(4), two equivalent Zr(3), one Ni(1), one Ni(10), one Ni(11), one Ni(2), one Ni(5), one Ni(7), and one Ni(9) atom to form distorted NiZr5Ni7 cuboctahedra that share  a cornercorner with one Ni(6)Zr5Ni7 cuboctahedra,  an edgeedge with one Ni(6)Zr5Ni7 cuboctahedra,  a faceface with one Ni(1)Zr4Ni8 cuboctahedra, and faces with three equivalent Ni(2)Zr5Ni7 cuboctahedra. In the seventh Ni site, Ni(7) is bonded in a 12-coordinate geometry to one Zr(3), one Zr(4), two equivalent Zr(2), one Ni(11), one Ni(4), one Ni(5), one Ni(6), one Ni(7), one Ni(8), and two equivalent Ni(9) atoms. In the eighth Ni site, Ni(8) is bonded in a 12-coordinate geometry to one Zr(1), one Zr(2), one Zr(3), two equivalent Zr(4), one Ni(10), one Ni(2), one Ni(4), one Ni(7), one Ni(9), and two equivalent Ni(3) atoms. In the ninth Ni site, Ni(9) is bonded in a 3-coordinate geometry to one Zr(2), one Zr(4), two equivalent Zr(1), one Ni(4), one Ni(5), one Ni(6), one Ni(8), and two equivalent Ni(7) atoms. In the tenth Ni site, Ni(10) is bonded in a 12-coordinate geometry to one Zr(3), one Zr(4), two equivalent Zr(1), one Ni(1), one Ni(10), one Ni(2), one Ni(5), one Ni(6), one Ni(8), and two equivalent Ni(11) atoms. In the eleventh Ni site, Ni(11) is bonded in a 4-coordinate geometry to one Zr(1), one Zr(4), two equivalent Zr(3), one Ni(1), one Ni(2), one Ni(4), one Ni(5), one Ni(6), one Ni(7), and two equivalent Ni(10) atoms.
Zr8Ni21 crystallizes in the triclinic P-1 space group. There are four inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a 13-coordinate geometry to one Ni(1), one Ni(11), one Ni(2), one Ni(4), one Ni(5), one Ni(6), one Ni(8), two equivalent Ni(10), two equivalent Ni(3), and two equivalent Ni(9) atoms. The Zr(1)-Ni(1) bond length is 2.80 Å. The Zr(1)-Ni(11) bond length is 2.66 Å. The Zr(1)-Ni(2) bond length is 2.80 Å. The Zr(1)-Ni(4) bond length is 2.70 Å. The Zr(1)-Ni(5) bond length is 2.79 Å. The Zr(1)-Ni(6) bond length is 2.97 Å. The Zr(1)-Ni(8) bond length is 2.70 Å. There is one shorter (2.69 Å) and one longer (2.74 Å) Zr(1)-Ni(10) bond length. There is one shorter (2.64 Å) and one longer (2.68 Å) Zr(1)-Ni(3) bond length. There is one shorter (2.70 Å) and one longer (3.09 Å) Zr(1)-Ni(9) bond length. In the second Zr site, Zr(2) is bonded in a 10-coordinate geometry to one Ni(2), one Ni(3), one Ni(4), one Ni(6), one Ni(8), one Ni(9), two equivalent Ni(5), and two equivalent Ni(7) atoms. The Zr(2)-Ni(2) bond length is 2.68 Å. The Zr(2)-Ni(3) bond length is 2.60 Å. The Zr(2)-Ni(4) bond length is 2.68 Å. The Zr(2)-Ni(6) bond length is 2.74 Å. The Zr(2)-Ni(8) bond length is 2.64 Å. The Zr(2)-Ni(9) bond length is 2.65 Å. There is one shorter (2.65 Å) and one longer (2.80 Å) Zr(2)-Ni(5) bond length. There is one shorter (2.62 Å) and one longer (2.65 Å) Zr(2)-Ni(7) bond length. In the third Zr site, Zr(3) is bonded in a 12-coordinate geometry to one Ni(10), one Ni(5), one Ni(7), one Ni(8), two equivalent Ni(11), two equivalent Ni(2), two equivalent Ni(4), and two equivalent Ni(6) atoms. The Zr(3)-Ni(10) bond length is 2.65 Å. The Zr(3)-Ni(5) bond length is 2.90 Å. The Zr(3)-Ni(7) bond length is 2.85 Å. The Zr(3)-Ni(8) bond length is 2.76 Å. There is one shorter (2.67 Å) and one longer (2.73 Å) Zr(3)-Ni(11) bond length. There is one shorter (2.80 Å) and one longer (2.84 Å) Zr(3)-Ni(2) bond length. There is one shorter (2.66 Å) and one longer (2.69 Å) Zr(3)-Ni(4) bond length. There is one shorter (2.82 Å) and one longer (2.87 Å) Zr(3)-Ni(6) bond length. In the fourth Zr site, Zr(4) is bonded in a 12-coordinate geometry to one Ni(1), one Ni(10), one Ni(11), one Ni(2), one Ni(5), one Ni(6), one Ni(7), one Ni(9), two equivalent Ni(3), and two equivalent Ni(8) atoms. The Zr(4)-Ni(1) bond length is 2.78 Å. The Zr(4)-Ni(10) bond length is 2.69 Å. The Zr(4)-Ni(11) bond length is 2.68 Å. The Zr(4)-Ni(2) bond length is 2.86 Å. The Zr(4)-Ni(5) bond length is 2.69 Å. The Zr(4)-Ni(6) bond length is 2.87 Å. The Zr(4)-Ni(7) bond length is 2.71 Å. The Zr(4)-Ni(9) bond length is 2.70 Å. There is one shorter (2.61 Å) and one longer (2.66 Å) Zr(4)-Ni(3) bond length. There is one shorter (2.72 Å) and one longer (2.76 Å) Zr(4)-Ni(8) bond length. There are eleven inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Zr(1), two equivalent Zr(4), two equivalent Ni(10), two equivalent Ni(11), two equivalent Ni(2), and two equivalent Ni(6) atoms to form face-sharing NiZr4Ni8 cuboctahedra. Both Ni(1)-Ni(10) bond lengths are 2.51 Å. Both Ni(1)-Ni(11) bond lengths are 2.59 Å. Both Ni(1)-Ni(2) bond lengths are 2.44 Å. Both Ni(1)-Ni(6) bond lengths are 2.42 Å. In the second Ni site, Ni(2) is bonded to one Zr(1), one Zr(2), one Zr(4), two equivalent Zr(3), one Ni(1), one Ni(10), one Ni(11), one Ni(3), one Ni(4), one Ni(6), and one Ni(8) atom to form distorted NiZr5Ni7 cuboctahedra that share  a cornercorner with one Ni(2)Zr5Ni7 cuboctahedra,  an edgeedge with one Ni(2)Zr5Ni7 cuboctahedra,  a faceface with one Ni(1)Zr4Ni8 cuboctahedra, and faces with three equivalent Ni(6)Zr5Ni7 cuboctahedra. The Ni(2)-Ni(10) bond length is 2.55 Å. The Ni(2)-Ni(11) bond length is 2.57 Å. The Ni(2)-Ni(3) bond length is 2.58 Å. The Ni(2)-Ni(4) bond length is 2.55 Å. The Ni(2)-Ni(6) bond length is 2.43 Å. The Ni(2)-Ni(8) bond length is 2.54 Å. In the third Ni site, Ni(3) is bonded in a 5-coordinate geometry to one Zr(2), two equivalent Zr(1), two equivalent Zr(4), one Ni(2), one Ni(5), and two equivalent Ni(8) atoms. The Ni(3)-Ni(5) bond length is 2.66 Å. There is one shorter (2.77 Å) and one longer (2.87 Å) Ni(3)-Ni(8) bond length. In the fourth Ni site, Ni(4) is bonded in a 10-coordinate geometry to one Zr(1), one Zr(2), two equivalent Zr(3), one Ni(11), one Ni(2), one Ni(5), one Ni(7), one Ni(8), and one Ni(9) atom. The Ni(4)-Ni(11) bond length is 2.68 Å. The Ni(4)-Ni(5) bond length is 2.70 Å. The Ni(4)-Ni(7) bond length is 2.39 Å. The Ni(4)-Ni(8) bond length is 2.69 Å. The Ni(4)-Ni(9) bond length is 2.47 Å. In the fifth Ni site, Ni(5) is bonded in a 12-coordinate geometry to one Zr(1), one Zr(3), one Zr(4), two equivalent Zr(2), one Ni(10), one Ni(11), one Ni(3), one Ni(4), one Ni(6), one Ni(7), and one Ni(9) atom. The Ni(5)-Ni(10) bond length is 2.74 Å. The Ni(5)-Ni(11) bond length is 2.47 Å. The Ni(5)-Ni(6) bond length is 2.51 Å. The Ni(5)-Ni(7) bond length is 2.73 Å. The Ni(5)-Ni(9) bond length is 2.59 Å. In the sixth Ni site, Ni(6) is bonded to one Zr(1), one Zr(2), one Zr(4), two equivalent Zr(3), one Ni(1), one Ni(10), one Ni(11), one Ni(2), one Ni(5), one Ni(7), and one Ni(9) atom to form distorted NiZr5Ni7 cuboctahedra that share  a cornercorner with one Ni(6)Zr5Ni7 cuboctahedra,  an edgeedge with one Ni(6)Zr5Ni7 cuboctahedra,  a faceface with one Ni(1)Zr4Ni8 cuboctahedra, and faces with three equivalent Ni(2)Zr5Ni7 cuboctahedra. The Ni(6)-Ni(10) bond length is 2.49 Å. The Ni(6)-Ni(11) bond length is 2.54 Å. The Ni(6)-Ni(7) bond length is 2.49 Å. The Ni(6)-Ni(9) bond length is 2.49 Å. In the seventh Ni site, Ni(7) is bonded in a 12-coordinate geometry to one Zr(3), one Zr(4), two equivalent Zr(2), one Ni(11), one Ni(4), one Ni(5), one Ni(6), one Ni(7), one Ni(8), and two equivalent Ni(9) atoms. The Ni(7)-Ni(11) bond length is 2.67 Å. The Ni(7)-Ni(7) bond length is 2.54 Å. The Ni(7)-Ni(8) bond length is 2.75 Å. There is one shorter (2.75 Å) and one longer (2.88 Å) Ni(7)-Ni(9) bond length. In the eighth Ni site, Ni(8) is bonded in a 12-coordinate geometry to one Zr(1), one Zr(2), one Zr(3), two equivalent Zr(4), one Ni(10), one Ni(2), one Ni(4), one Ni(7), one Ni(9), and two equivalent Ni(3) atoms. The Ni(8)-Ni(10) bond length is 2.74 Å. The Ni(8)-Ni(9) bond length is 2.43 Å. In the ninth Ni site, Ni(9) is bonded in a 3-coordinate geometry to one Zr(2), one Zr(4), two equivalent Zr(1), one Ni(4), one Ni(5), one Ni(6), one Ni(8), and two equivalent Ni(7) atoms. In the tenth Ni site, Ni(10) is bonded in a 12-coordinate geometry to one Zr(3), one Zr(4), two equivalent Zr(1), one Ni(1), one Ni(10), one Ni(2), one Ni(5), one Ni(6), one Ni(8), and two equivalent Ni(11) atoms. The Ni(10)-Ni(10) bond length is 2.46 Å. There is one shorter (2.74 Å) and one longer (2.84 Å) Ni(10)-Ni(11) bond length. In the eleventh Ni site, Ni(11) is bonded in a 4-coordinate geometry to one Zr(1), one Zr(4), two equivalent Zr(3), one Ni(1), one Ni(2), one Ni(4), one Ni(5), one Ni(6), one Ni(7), and two equivalent Ni(10) atoms.