K(SiAs)3 crystallizes in the orthorhombic Pbam space group. K(1) is bonded in a 6-coordinate geometry to two equivalent As(2) and four equivalent As(1) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(1), one As(2), and two equivalent As(3) atoms to form SiSiAs3 tetrahedra that share corners with two equivalent Si(2)Si2As2 tetrahedra, corners with two equivalent Si(1)SiAs3 tetrahedra, and  a cornercorner with one As(2)K2Si3 trigonal bipyramid. In the second Si site, Si(2) is bonded to one Si(2), one Si(3), and two equivalent As(2) atoms to form distorted SiSi2As2 tetrahedra that share corners with two equivalent Si(2)Si2As2 tetrahedra, corners with two equivalent Si(1)SiAs3 tetrahedra, and corners with two equivalent As(2)K2Si3 trigonal bipyramids. In the third Si site, Si(3) is bonded in a 3-coordinate geometry to one Si(2), one As(3), and two equivalent As(1) atoms. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 6-coordinate geometry to four equivalent K(1) and two equivalent Si(3) atoms. In the second As site, As(2) is bonded to two equivalent K(1), one Si(1), and two equivalent Si(2) atoms to form distorted AsK2Si3 trigonal bipyramids that share  a cornercorner with one Si(1)SiAs3 tetrahedra, corners with two equivalent Si(2)Si2As2 tetrahedra, and edges with two equivalent As(2)K2Si3 trigonal bipyramids. In the third As site, As(3) is bonded in a 3-coordinate geometry to one Si(3) and two equivalent Si(1) atoms.
K(SiAs)3 crystallizes in the orthorhombic Pbam space group. K(1) is bonded in a 6-coordinate geometry to two equivalent As(2) and four equivalent As(1) atoms. Both K(1)-As(2) bond lengths are 3.52 Å. There are two shorter (3.46 Å) and two longer (3.50 Å) K(1)-As(1) bond lengths. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(1), one As(2), and two equivalent As(3) atoms to form SiSiAs3 tetrahedra that share corners with two equivalent Si(2)Si2As2 tetrahedra, corners with two equivalent Si(1)SiAs3 tetrahedra, and  a cornercorner with one As(2)K2Si3 trigonal bipyramid. The Si(1)-Si(1) bond length is 2.33 Å. The Si(1)-As(2) bond length is 2.41 Å. Both Si(1)-As(3) bond lengths are 2.38 Å. In the second Si site, Si(2) is bonded to one Si(2), one Si(3), and two equivalent As(2) atoms to form distorted SiSi2As2 tetrahedra that share corners with two equivalent Si(2)Si2As2 tetrahedra, corners with two equivalent Si(1)SiAs3 tetrahedra, and corners with two equivalent As(2)K2Si3 trigonal bipyramids. The Si(2)-Si(2) bond length is 2.33 Å. The Si(2)-Si(3) bond length is 2.34 Å. Both Si(2)-As(2) bond lengths are 2.38 Å. In the third Si site, Si(3) is bonded in a 3-coordinate geometry to one Si(2), one As(3), and two equivalent As(1) atoms. The Si(3)-As(3) bond length is 2.43 Å. Both Si(3)-As(1) bond lengths are 2.34 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 6-coordinate geometry to four equivalent K(1) and two equivalent Si(3) atoms. In the second As site, As(2) is bonded to two equivalent K(1), one Si(1), and two equivalent Si(2) atoms to form distorted AsK2Si3 trigonal bipyramids that share  a cornercorner with one Si(1)SiAs3 tetrahedra, corners with two equivalent Si(2)Si2As2 tetrahedra, and edges with two equivalent As(2)K2Si3 trigonal bipyramids. In the third As site, As(3) is bonded in a 3-coordinate geometry to one Si(3) and two equivalent Si(1) atoms.