Ni(GeO3)2 crystallizes in the monoclinic P2_1/c space group. Ni(1) is bonded to one O(3), one O(4), two equivalent O(5), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent Ge(1)O4 tetrahedra, corners with two equivalent Ge(2)O5 trigonal bipyramids, edges with two equivalent Ni(1)O6 octahedra, and  an edgeedge with one Ge(2)O5 trigonal bipyramid. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(4), one O(5), and two equivalent O(2) atoms to form GeO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-61°. In the second Ge site, Ge(2) is bonded to one O(6), two equivalent O(1), and two equivalent O(3) atoms to form GeO5 trigonal bipyramids that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ge(2)O5 trigonal bipyramids,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Ge(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 36-45°. There are six inequivalent O sites. In the first O site, O(6) is bonded in a trigonal non-coplanar geometry to two equivalent Ni(1) and one Ge(2) atom. In the second O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Ge(2) atoms. In the third O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Ge(1) atoms. In the fourth O site, O(3) is bonded in a distorted T-shaped geometry to one Ni(1) and two equivalent Ge(2) atoms. In the fifth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one Ge(1) atom. In the sixth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one Ge(1) atom.
Ni(GeO3)2 crystallizes in the monoclinic P2_1/c space group. Ni(1) is bonded to one O(3), one O(4), two equivalent O(5), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent Ge(1)O4 tetrahedra, corners with two equivalent Ge(2)O5 trigonal bipyramids, edges with two equivalent Ni(1)O6 octahedra, and  an edgeedge with one Ge(2)O5 trigonal bipyramid. The Ni(1)-O(3) bond length is 2.13 Å. The Ni(1)-O(4) bond length is 1.92 Å. There is one shorter (1.94 Å) and one longer (2.15 Å) Ni(1)-O(5) bond length. There is one shorter (1.93 Å) and one longer (1.94 Å) Ni(1)-O(6) bond length. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(4), one O(5), and two equivalent O(2) atoms to form GeO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-61°. The Ge(1)-O(4) bond length is 1.76 Å. The Ge(1)-O(5) bond length is 1.80 Å. Both Ge(1)-O(2) bond lengths are 1.77 Å. In the second Ge site, Ge(2) is bonded to one O(6), two equivalent O(1), and two equivalent O(3) atoms to form GeO5 trigonal bipyramids that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ge(2)O5 trigonal bipyramids,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Ge(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 36-45°. The Ge(2)-O(6) bond length is 1.83 Å. There is one shorter (1.78 Å) and one longer (1.81 Å) Ge(2)-O(1) bond length. There is one shorter (1.81 Å) and one longer (2.06 Å) Ge(2)-O(3) bond length. There are six inequivalent O sites. In the first O site, O(6) is bonded in a trigonal non-coplanar geometry to two equivalent Ni(1) and one Ge(2) atom. In the second O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Ge(2) atoms. In the third O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Ge(1) atoms. In the fourth O site, O(3) is bonded in a distorted T-shaped geometry to one Ni(1) and two equivalent Ge(2) atoms. In the fifth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one Ge(1) atom. In the sixth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one Ge(1) atom.