Fe12Ge3As2 crystallizes in the trigonal R32 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to three equivalent Fe(4), two equivalent Ge(1), and two equivalent As(1) atoms. In the second Fe site, Fe(2) is bonded in a 3-coordinate geometry to three equivalent Fe(4) and three equivalent Ge(1) atoms. In the third Fe site, Fe(3) is bonded in a trigonal bipyramidal geometry to three equivalent Ge(1) and two equivalent As(1) atoms. In the fourth Fe site, Fe(4) is bonded in a 14-coordinate geometry to two equivalent Fe(2), two equivalent Fe(4), six equivalent Fe(1), two equivalent Ge(1), and two equivalent As(1) atoms. Ge(1) is bonded in a 9-coordinate geometry to one Fe(3), two equivalent Fe(2), two equivalent Fe(4), and four equivalent Fe(1) atoms. As(1) is bonded in a 10-coordinate geometry to one Fe(3), three equivalent Fe(4), and six equivalent Fe(1) atoms.
Fe12Ge3As2 crystallizes in the trigonal R32 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to three equivalent Fe(4), two equivalent Ge(1), and two equivalent As(1) atoms. There are a spread of Fe(1)-Fe(4) bond distances ranging from 2.49-2.90 Å. There is one shorter (2.41 Å) and one longer (2.52 Å) Fe(1)-Ge(1) bond length. There is one shorter (2.45 Å) and one longer (2.64 Å) Fe(1)-As(1) bond length. In the second Fe site, Fe(2) is bonded in a 3-coordinate geometry to three equivalent Fe(4) and three equivalent Ge(1) atoms. All Fe(2)-Fe(4) bond lengths are 2.47 Å. All Fe(2)-Ge(1) bond lengths are 2.39 Å. In the third Fe site, Fe(3) is bonded in a trigonal bipyramidal geometry to three equivalent Ge(1) and two equivalent As(1) atoms. All Fe(3)-Ge(1) bond lengths are 2.38 Å. Both Fe(3)-As(1) bond lengths are 2.33 Å. In the fourth Fe site, Fe(4) is bonded in a 14-coordinate geometry to two equivalent Fe(2), two equivalent Fe(4), six equivalent Fe(1), two equivalent Ge(1), and two equivalent As(1) atoms. Both Fe(4)-Fe(4) bond lengths are 2.84 Å. Both Fe(4)-Ge(1) bond lengths are 2.74 Å. Both Fe(4)-As(1) bond lengths are 2.68 Å. Ge(1) is bonded in a 9-coordinate geometry to one Fe(3), two equivalent Fe(2), two equivalent Fe(4), and four equivalent Fe(1) atoms. As(1) is bonded in a 10-coordinate geometry to one Fe(3), three equivalent Fe(4), and six equivalent Fe(1) atoms.