BaAs2O5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one O(4), one O(5), one O(6), one O(7), one O(8), one O(9), two equivalent O(1), and two equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(10), one O(2), one O(4), one O(6), one O(7), one O(8), one O(9), and two equivalent O(5) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded in a distorted T-shaped geometry to one O(1), one O(4), and one O(5) atom. In the second As site, As(2) is bonded in a distorted T-shaped geometry to one O(1), one O(2), and one O(6) atom. In the third As site, As(3) is bonded in a distorted T-shaped geometry to one O(2), one O(3), and one O(7) atom. In the fourth As site, As(4) is bonded in a distorted T-shaped geometry to one O(3), one O(4), and one O(8) atom. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one As(1), and one As(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ba(2), one As(2), and one As(3) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one As(3), and one As(4) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one As(1), and one As(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ba(1), two equivalent Ba(2), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(2), and one As(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), and one As(4) atom. In the ninth O site, O(9) is bonded in an L-shaped geometry to one Ba(1) and one Ba(2) atom. In the tenth O site, O(10) is bonded in a bent 120 degrees geometry to one Ba(2) and one O(10) atom.
BaAs2O5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one O(4), one O(5), one O(6), one O(7), one O(8), one O(9), two equivalent O(1), and two equivalent O(3) atoms. The Ba(1)-O(4) bond length is 3.32 Å. The Ba(1)-O(5) bond length is 2.80 Å. The Ba(1)-O(6) bond length is 2.74 Å. The Ba(1)-O(7) bond length is 2.74 Å. The Ba(1)-O(8) bond length is 2.75 Å. The Ba(1)-O(9) bond length is 3.01 Å. There is one shorter (3.06 Å) and one longer (3.11 Å) Ba(1)-O(1) bond length. There is one shorter (3.06 Å) and one longer (3.13 Å) Ba(1)-O(3) bond length. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(10), one O(2), one O(4), one O(6), one O(7), one O(8), one O(9), and two equivalent O(5) atoms. The Ba(2)-O(10) bond length is 3.31 Å. The Ba(2)-O(2) bond length is 2.83 Å. The Ba(2)-O(4) bond length is 2.78 Å. The Ba(2)-O(6) bond length is 2.91 Å. The Ba(2)-O(7) bond length is 2.96 Å. The Ba(2)-O(8) bond length is 2.73 Å. The Ba(2)-O(9) bond length is 3.10 Å. There is one shorter (2.73 Å) and one longer (3.02 Å) Ba(2)-O(5) bond length. There are four inequivalent As sites. In the first As site, As(1) is bonded in a distorted T-shaped geometry to one O(1), one O(4), and one O(5) atom. The As(1)-O(1) bond length is 1.88 Å. The As(1)-O(4) bond length is 1.88 Å. The As(1)-O(5) bond length is 1.73 Å. In the second As site, As(2) is bonded in a distorted T-shaped geometry to one O(1), one O(2), and one O(6) atom. The As(2)-O(1) bond length is 1.88 Å. The As(2)-O(2) bond length is 1.85 Å. The As(2)-O(6) bond length is 1.73 Å. In the third As site, As(3) is bonded in a distorted T-shaped geometry to one O(2), one O(3), and one O(7) atom. The As(3)-O(2) bond length is 1.84 Å. The As(3)-O(3) bond length is 1.87 Å. The As(3)-O(7) bond length is 1.74 Å. In the fourth As site, As(4) is bonded in a distorted T-shaped geometry to one O(3), one O(4), and one O(8) atom. The As(4)-O(3) bond length is 1.89 Å. The As(4)-O(4) bond length is 1.87 Å. The As(4)-O(8) bond length is 1.72 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one As(1), and one As(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ba(2), one As(2), and one As(3) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one As(3), and one As(4) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one As(1), and one As(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ba(1), two equivalent Ba(2), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(2), and one As(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), and one As(4) atom. In the ninth O site, O(9) is bonded in an L-shaped geometry to one Ba(1) and one Ba(2) atom. In the tenth O site, O(10) is bonded in a bent 120 degrees geometry to one Ba(2) and one O(10) atom. The O(10)-O(10) bond length is 1.24 Å.