Ba3Ir2H12 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent H(2) and four equivalent H(1) atoms to form BaH6 octahedra that share edges with two equivalent Ir(1)Ba2H5 pentagonal bipyramids. In the second Ba site, Ba(2) is bonded in a 5-coordinate geometry to two equivalent Ir(1), one H(2), and two equivalent H(1) atoms. Ir(1) is bonded to two equivalent Ba(2), one H(4), two equivalent H(1), and two equivalent H(3) atoms to form IrBa2H5 pentagonal bipyramids that share corners with two equivalent Ir(1)Ba2H5 pentagonal bipyramids and  an edgeedge with one Ba(1)H6 octahedra. There are four inequivalent H sites. In the first H site, H(1) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), and one Ir(1) atom. In the second H site, H(2) is bonded in a bent 120 degrees geometry to one Ba(1) and one Ba(2) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Ir(1) atom. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one Ir(1) atom.
Ba3Ir2H12 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent H(2) and four equivalent H(1) atoms to form BaH6 octahedra that share edges with two equivalent Ir(1)Ba2H5 pentagonal bipyramids. Both Ba(1)-H(2) bond lengths are 2.57 Å. All Ba(1)-H(1) bond lengths are 2.85 Å. In the second Ba site, Ba(2) is bonded in a 5-coordinate geometry to two equivalent Ir(1), one H(2), and two equivalent H(1) atoms. There is one shorter (2.65 Å) and one longer (2.66 Å) Ba(2)-Ir(1) bond length. The Ba(2)-H(2) bond length is 2.53 Å. Both Ba(2)-H(1) bond lengths are 3.01 Å. Ir(1) is bonded to two equivalent Ba(2), one H(4), two equivalent H(1), and two equivalent H(3) atoms to form IrBa2H5 pentagonal bipyramids that share corners with two equivalent Ir(1)Ba2H5 pentagonal bipyramids and  an edgeedge with one Ba(1)H6 octahedra. The Ir(1)-H(4) bond length is 1.63 Å. Both Ir(1)-H(1) bond lengths are 1.67 Å. Both Ir(1)-H(3) bond lengths are 1.65 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), and one Ir(1) atom. In the second H site, H(2) is bonded in a bent 120 degrees geometry to one Ba(1) and one Ba(2) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Ir(1) atom. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one Ir(1) atom.