Crystal Structure of Tetrakis (phenacetin) Dihydrogentetraiodide Dihydrate {[H₅C₂OC₆H₄N (H)C(CH₃)O]₄·H₂I₄·2H₂O}

(Phenacetin) 4 · 2 I 4 ·2H 2 O is triclinic, a = 13.641 (7), b = 12.807 (6), c = 7.201 (3) Å, α = 99.8 (4), b̃ = 86.5 (4), γ = 104.0 (5)°, P 1 , Z = 1. The ordered crystal structure has been refined to R F = 0.050, using 4173 independent reflections measured on a four‐circle diffractometer with Mo Ka (graphite monochromator) radiation. The crystals are composed of alternating positively and negatively charged slices; each positive slice contains a double layer of stacks of hemi‐protonated phenacetin molecules which are H‐bonded through their carbonyl groups (d(O ‐ ‐ ‐ O) = 2.432 (4) Å) while each negative slice contains a single layer of I 2− 4 ‐ions linked in chains along [100] through H‐bonds to pairs of water molecules. The axes of the phenacetin stacks are parallel to the planes of the (I 2− 4 ·2H 2 O)‐layers. The I 2− 4 ‐ion is centro‐symmetric and can be approximately represented as I − ‐ ‐ ‐ I–I‐ ‐ ‐ I − (d(I − ‐ ‐ ‐ I) = 3.404 (1) Å; d(I–I) = 2.774 (1) Å). The compound is a pseudo‐type A basic salt.