NaBSi2O7 crystallizes in the monoclinic P2_1 space group. Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), two equivalent O(6), and two equivalent O(7) atoms. B(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form BO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and  a cornercorner with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one B(1)O4 tetrahedra and corners with three equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one B(1)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Na(1), one B(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1), one B(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Na(1) and one B(1) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to two equivalent Na(1) and one B(1) atom.
NaBSi2O7 crystallizes in the monoclinic P2_1 space group. Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), two equivalent O(6), and two equivalent O(7) atoms. The Na(1)-O(1) bond length is 3.01 Å. The Na(1)-O(3) bond length is 2.60 Å. The Na(1)-O(4) bond length is 2.59 Å. There is one shorter (2.54 Å) and one longer (2.73 Å) Na(1)-O(6) bond length. There is one shorter (2.44 Å) and one longer (2.48 Å) Na(1)-O(7) bond length. B(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form BO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and  a cornercorner with one Si(2)O4 tetrahedra. The B(1)-O(3) bond length is 1.46 Å. The B(1)-O(4) bond length is 1.46 Å. The B(1)-O(6) bond length is 1.45 Å. The B(1)-O(7) bond length is 1.45 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one B(1)O4 tetrahedra and corners with three equivalent Si(2)O4 tetrahedra. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(2) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.62 Å. The Si(1)-O(5) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one B(1)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. The Si(2)-O(1) bond length is 1.64 Å. The Si(2)-O(2) bond length is 1.63 Å. The Si(2)-O(3) bond length is 1.61 Å. The Si(2)-O(5) bond length is 1.63 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Na(1), one B(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1), one B(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Na(1) and one B(1) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to two equivalent Na(1) and one B(1) atom.