Ba7Ga4As9 crystallizes in the orthorhombic Pmmn space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one Ga(1), two equivalent As(2), and four equivalent As(1) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Ga(1), one As(3), one As(4), one As(5), two equivalent As(1), and two equivalent As(2) atoms. In the third Ba site, Ba(3) is bonded in a 1-coordinate geometry to one As(5) and four equivalent As(1) atoms. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one Ba(1), two equivalent Ba(2), one As(2), one As(5), and two equivalent As(1) atoms to form distorted GaBa3As4 tetrahedra that share  a cornercorner with one Ga(1)Ba3As4 tetrahedra and corners with two equivalent Ga(2)As4 tetrahedra. In the second Ga site, Ga(2) is bonded to one As(3), one As(4), and two equivalent As(1) atoms to form distorted GaAs4 tetrahedra that share corners with two equivalent Ga(1)Ba3As4 tetrahedra and  an edgeedge with one Ga(2)As4 tetrahedra. There are five inequivalent As sites. In the first As site, As(3) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the second As site, As(4) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the third As site, As(5) is bonded in a distorted trigonal planar geometry to one Ba(3), four equivalent Ba(2), and two equivalent Ga(1) atoms. In the fourth As site, As(1) is bonded in a 7-coordinate geometry to one Ba(3), two equivalent Ba(1), two equivalent Ba(2), one Ga(1), and one Ga(2) atom. In the fifth As site, As(2) is bonded in a 7-coordinate geometry to two equivalent Ba(1), four equivalent Ba(2), and one Ga(1) atom.
Ba7Ga4As9 crystallizes in the orthorhombic Pmmn space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one Ga(1), two equivalent As(2), and four equivalent As(1) atoms. The Ba(1)-Ga(1) bond length is 3.50 Å. There is one shorter (3.35 Å) and one longer (3.70 Å) Ba(1)-As(2) bond length. There are two shorter (3.35 Å) and two longer (3.51 Å) Ba(1)-As(1) bond lengths. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Ga(1), one As(3), one As(4), one As(5), two equivalent As(1), and two equivalent As(2) atoms. The Ba(2)-Ga(1) bond length is 3.46 Å. The Ba(2)-As(3) bond length is 3.58 Å. The Ba(2)-As(4) bond length is 3.48 Å. The Ba(2)-As(5) bond length is 3.63 Å. There is one shorter (3.46 Å) and one longer (3.54 Å) Ba(2)-As(1) bond length. There is one shorter (3.30 Å) and one longer (3.48 Å) Ba(2)-As(2) bond length. In the third Ba site, Ba(3) is bonded in a 1-coordinate geometry to one As(5) and four equivalent As(1) atoms. The Ba(3)-As(5) bond length is 3.11 Å. All Ba(3)-As(1) bond lengths are 3.25 Å. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one Ba(1), two equivalent Ba(2), one As(2), one As(5), and two equivalent As(1) atoms to form distorted GaBa3As4 tetrahedra that share  a cornercorner with one Ga(1)Ba3As4 tetrahedra and corners with two equivalent Ga(2)As4 tetrahedra. The Ga(1)-As(2) bond length is 2.43 Å. The Ga(1)-As(5) bond length is 2.48 Å. Both Ga(1)-As(1) bond lengths are 2.56 Å. In the second Ga site, Ga(2) is bonded to one As(3), one As(4), and two equivalent As(1) atoms to form distorted GaAs4 tetrahedra that share corners with two equivalent Ga(1)Ba3As4 tetrahedra and  an edgeedge with one Ga(2)As4 tetrahedra. The Ga(2)-As(3) bond length is 2.55 Å. The Ga(2)-As(4) bond length is 2.55 Å. Both Ga(2)-As(1) bond lengths are 2.49 Å. There are five inequivalent As sites. In the first As site, As(3) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the second As site, As(4) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the third As site, As(5) is bonded in a distorted trigonal planar geometry to one Ba(3), four equivalent Ba(2), and two equivalent Ga(1) atoms. In the fourth As site, As(1) is bonded in a 7-coordinate geometry to one Ba(3), two equivalent Ba(1), two equivalent Ba(2), one Ga(1), and one Ga(2) atom. In the fifth As site, As(2) is bonded in a 7-coordinate geometry to two equivalent Ba(1), four equivalent Ba(2), and one Ga(1) atom.