Hf2As crystallizes in the orthorhombic Pnnm space group. There are six inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 4-coordinate geometry to two equivalent As(2) and two equivalent As(3) atoms. In the second Hf site, Hf(2) is bonded in a 5-coordinate geometry to one As(2), two equivalent As(1), and two equivalent As(3) atoms. In the third Hf site, Hf(3) is bonded in a 3-coordinate geometry to one As(1) and two equivalent As(2) atoms. In the fourth Hf site, Hf(4) is bonded in a distorted T-shaped geometry to one As(1), one As(2), and one As(3) atom. In the fifth Hf site, Hf(5) is bonded to one As(3), two equivalent As(1), and two equivalent As(2) atoms to form distorted edge-sharing HfAs5 trigonal bipyramids. In the sixth Hf site, Hf(6) is bonded in a 4-coordinate geometry to one As(2), one As(3), and two equivalent As(1) atoms. There are three inequivalent As sites. In the first As site, As(3) is bonded to one Hf(4), one Hf(5), one Hf(6), two equivalent Hf(1), and two equivalent Hf(2) atoms to form distorted edge-sharing AsHf7 pentagonal bipyramids. In the second As site, As(1) is bonded in a 8-coordinate geometry to one Hf(3), one Hf(4), two equivalent Hf(2), two equivalent Hf(5), and two equivalent Hf(6) atoms. In the third As site, As(2) is bonded in a 9-coordinate geometry to one Hf(2), one Hf(4), one Hf(6), two equivalent Hf(1), two equivalent Hf(3), and two equivalent Hf(5) atoms.
Hf2As crystallizes in the orthorhombic Pnnm space group. There are six inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 4-coordinate geometry to two equivalent As(2) and two equivalent As(3) atoms. Both Hf(1)-As(2) bond lengths are 2.82 Å. Both Hf(1)-As(3) bond lengths are 2.73 Å. In the second Hf site, Hf(2) is bonded in a 5-coordinate geometry to one As(2), two equivalent As(1), and two equivalent As(3) atoms. The Hf(2)-As(2) bond length is 3.09 Å. Both Hf(2)-As(1) bond lengths are 2.76 Å. Both Hf(2)-As(3) bond lengths are 2.72 Å. In the third Hf site, Hf(3) is bonded in a 3-coordinate geometry to one As(1) and two equivalent As(2) atoms. The Hf(3)-As(1) bond length is 2.80 Å. Both Hf(3)-As(2) bond lengths are 2.73 Å. In the fourth Hf site, Hf(4) is bonded in a distorted T-shaped geometry to one As(1), one As(2), and one As(3) atom. The Hf(4)-As(1) bond length is 2.88 Å. The Hf(4)-As(2) bond length is 2.88 Å. The Hf(4)-As(3) bond length is 2.78 Å. In the fifth Hf site, Hf(5) is bonded to one As(3), two equivalent As(1), and two equivalent As(2) atoms to form distorted edge-sharing HfAs5 trigonal bipyramids. The Hf(5)-As(3) bond length is 2.70 Å. Both Hf(5)-As(1) bond lengths are 2.75 Å. Both Hf(5)-As(2) bond lengths are 2.74 Å. In the sixth Hf site, Hf(6) is bonded in a 4-coordinate geometry to one As(2), one As(3), and two equivalent As(1) atoms. The Hf(6)-As(2) bond length is 3.04 Å. The Hf(6)-As(3) bond length is 2.69 Å. Both Hf(6)-As(1) bond lengths are 2.80 Å. There are three inequivalent As sites. In the first As site, As(3) is bonded to one Hf(4), one Hf(5), one Hf(6), two equivalent Hf(1), and two equivalent Hf(2) atoms to form distorted edge-sharing AsHf7 pentagonal bipyramids. In the second As site, As(1) is bonded in a 8-coordinate geometry to one Hf(3), one Hf(4), two equivalent Hf(2), two equivalent Hf(5), and two equivalent Hf(6) atoms. In the third As site, As(2) is bonded in a 9-coordinate geometry to one Hf(2), one Hf(4), one Hf(6), two equivalent Hf(1), two equivalent Hf(3), and two equivalent Hf(5) atoms.