K4Na2PdH18(O10I)2 crystallizes in the triclinic P-1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 10-coordinate geometry to one H(2), one H(3), one H(4), one O(1), one O(4), one O(5), one O(6), one O(7), and two equivalent O(2) atoms. In the second K site, K(2) is bonded in a 3-coordinate geometry to one O(10), one O(2), one O(3), and one O(9) atom. Na(1) is bonded to one O(1), one O(10), one O(5), one O(6), one O(7), and one O(9) atom to form distorted NaO6 octahedra that share  an edgeedge with one I(1)O6 octahedra. Pd(1) is bonded in a square co-planar geometry to two equivalent O(3) and two equivalent O(9) atoms. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) and one O(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one K(1) and one O(1) atom. In the third H site, H(3) is bonded in a single-bond geometry to one K(1), one O(2), and one O(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one K(1) and one O(6) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(7) and one O(8) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(5) and one O(8) atom. In the seventh H site, H(7) is bonded in a distorted single-bond geometry to one O(10) and one O(4) atom. In the eighth H site, H(8) is bonded in a distorted single-bond geometry to one O(7) and one O(8) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(10) atom. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one K(1), one Na(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), one H(3), and one I(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(2), one Pd(1), one H(1), and one I(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(1), one H(7), and one I(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one K(1), one Na(1), one H(3), and one H(6) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(1), one Na(1), one H(4), and one I(1) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to one K(1), one Na(1), one H(5), and one H(8) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one H(5), one H(6), one H(8), and one I(1) atom. In the ninth O site, O(9) is bonded to one K(2), one Na(1), one Pd(1), and one I(1) atom to form corner-sharing OKNaPdI tetrahedra. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one K(2), one Na(1), one H(7), and one H(9) atom. I(1) is bonded to one O(2), one O(3), one O(4), one O(6), one O(8), and one O(9) atom to form IO6 octahedra that share  an edgeedge with one Na(1)O6 octahedra.
K4Na2PdH18(O10I)2 crystallizes in the triclinic P-1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 10-coordinate geometry to one H(2), one H(3), one H(4), one O(1), one O(4), one O(5), one O(6), one O(7), and two equivalent O(2) atoms. The K(1)-H(2) bond length is 2.79 Å. The K(1)-H(3) bond length is 2.94 Å. The K(1)-H(4) bond length is 2.91 Å. The K(1)-O(1) bond length is 2.89 Å. The K(1)-O(4) bond length is 2.86 Å. The K(1)-O(5) bond length is 3.31 Å. The K(1)-O(6) bond length is 2.86 Å. The K(1)-O(7) bond length is 2.91 Å. There is one shorter (2.74 Å) and one longer (2.94 Å) K(1)-O(2) bond length. In the second K site, K(2) is bonded in a 3-coordinate geometry to one O(10), one O(2), one O(3), and one O(9) atom. The K(2)-O(10) bond length is 2.76 Å. The K(2)-O(2) bond length is 2.99 Å. The K(2)-O(3) bond length is 2.72 Å. The K(2)-O(9) bond length is 2.72 Å. Na(1) is bonded to one O(1), one O(10), one O(5), one O(6), one O(7), and one O(9) atom to form distorted NaO6 octahedra that share  an edgeedge with one I(1)O6 octahedra. The Na(1)-O(1) bond length is 2.48 Å. The Na(1)-O(10) bond length is 2.37 Å. The Na(1)-O(5) bond length is 2.49 Å. The Na(1)-O(6) bond length is 2.48 Å. The Na(1)-O(7) bond length is 2.36 Å. The Na(1)-O(9) bond length is 2.42 Å. Pd(1) is bonded in a square co-planar geometry to two equivalent O(3) and two equivalent O(9) atoms. Both Pd(1)-O(3) bond lengths are 2.02 Å. Both Pd(1)-O(9) bond lengths are 2.02 Å. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) and one O(3) atom. The H(1)-O(1) bond length is 1.00 Å. The H(1)-O(3) bond length is 1.71 Å. In the second H site, H(2) is bonded in a single-bond geometry to one K(1) and one O(1) atom. The H(2)-O(1) bond length is 0.98 Å. In the third H site, H(3) is bonded in a single-bond geometry to one K(1), one O(2), and one O(5) atom. The H(3)-O(2) bond length is 1.70 Å. The H(3)-O(5) bond length is 1.01 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one K(1) and one O(6) atom. The H(4)-O(6) bond length is 1.00 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(7) and one O(8) atom. The H(5)-O(7) bond length is 1.00 Å. The H(5)-O(8) bond length is 1.76 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(5) and one O(8) atom. The H(6)-O(5) bond length is 1.00 Å. The H(6)-O(8) bond length is 1.77 Å. In the seventh H site, H(7) is bonded in a distorted single-bond geometry to one O(10) and one O(4) atom. The H(7)-O(10) bond length is 1.01 Å. The H(7)-O(4) bond length is 1.69 Å. In the eighth H site, H(8) is bonded in a distorted single-bond geometry to one O(7) and one O(8) atom. The H(8)-O(7) bond length is 1.00 Å. The H(8)-O(8) bond length is 1.70 Å. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(10) atom. The H(9)-O(10) bond length is 0.99 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one K(1), one Na(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), one H(3), and one I(1) atom. The O(2)-I(1) bond length is 1.86 Å. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(2), one Pd(1), one H(1), and one I(1) atom. The O(3)-I(1) bond length is 1.97 Å. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(1), one H(7), and one I(1) atom. The O(4)-I(1) bond length is 1.89 Å. In the fifth O site, O(5) is bonded in a water-like geometry to one K(1), one Na(1), one H(3), and one H(6) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(1), one Na(1), one H(4), and one I(1) atom. The O(6)-I(1) bond length is 2.04 Å. In the seventh O site, O(7) is bonded in a distorted water-like geometry to one K(1), one Na(1), one H(5), and one H(8) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one H(5), one H(6), one H(8), and one I(1) atom. The O(8)-I(1) bond length is 1.88 Å. In the ninth O site, O(9) is bonded to one K(2), one Na(1), one Pd(1), and one I(1) atom to form corner-sharing OKNaPdI tetrahedra. The O(9)-I(1) bond length is 1.96 Å. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one K(2), one Na(1), one H(7), and one H(9) atom. I(1) is bonded to one O(2), one O(3), one O(4), one O(6), one O(8), and one O(9) atom to form IO6 octahedra that share  an edgeedge with one Na(1)O6 octahedra.