The crystal structures of the polyiodide salts (phenacetin) ₂ HI ₅ and (theobromine) ₂ H ₂ I ₈

Abstract

The crystal structures of (phenacetin) 2 • H I 5 (triclinic, a — 12.44 A, b — 10.67, c = 5.81, oc = 103.3°, B — 103.7, y — 87.3, P1, Z = 1) and (theobromine) 2 H 2 I 8 (triclinic, a — 14.38 A, b = 14.07, c = 7.75, = 91.2°, B = 100.8, y = 91.0, P1, Z = 2) have been solved by Patterson methods, using intensities measured by Weissenberg diffractometer with graphite-monochromated Mo Ka radiation (2815 and 2827 intensities, R = 8.3 % and 11.1 % respectively). Both structures are polyiodide salts, with alternating cationic (organic) and anionic (polyiodide) layers. In (phenacetin) 2 • H I 5 the organic layers consist of hydrogen-bonded phenacetin 'dimers', with the proton bridging the oxygens of the carbonyl bonds in a short hydrogen bond ( d (O ...O ) = 2.46 (2) A); the polyiodide layers contain zigzag chains of alternating iodine molecules and triiodide ions, with secondary bonds ( d (I...I) = 3.55 A) between these moieties. There is only van der Waals bonding between parallel chains. This substance, bis- (phenacetin) hydrogen iodine triiodide, is a type A basic salt. In (theobromine) 2 • H 2 I 8 the organic layer consists of hydrogen-bonded theobrominium cations and the polyiodide layer of centrosymmetric S-shaped (I 4-16 ) ions, with the arrangement I - 3 •I - 2 •I - 3 •I - 3 •I - 2 •I - 3 ; there is secondary bonding between triiodide and iodine moieties within the hexadecaiodide ions. There are tertiary bonds (d/(I...I) = 3.84 A) between adjacent I 4-16 ions.

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

“…S), except for the region of the H-bonded carbonyl groups as discussed above; the mean dimensions are similar to those reported earlier [2] but are appreciably more accurate. Best planes were calculated through the ethoxy 0-atom, the six C-atoms of the benzene ring and the N-atom of the amide group for each of the independent molecules.…”

“…The single crystal was sealed into a capillary before starting the intensity measurements. Crystal data are given in Table 1 See [2].…”

“…-The title compound was obtained during a study of the crystal structure of (phenacetin), . HI5 (phenacetin = N-(4-ethoxyphenyl)-acetamide) [2]. IR.…”

New Conformations and Binding Modes in Halogen-Bonded and Ionic Complexes of 2,3,5,6-Tetra(2‘-pyridyl)pyrazine

“…The diiodine molecule (I3−I3B = 2.7742(11) Å) is also situated about a crystallographic 2-fold axis (−1/4, y , 1/4) which is coincident with the midpoint of the I−I bond. The I 3 - ···I 2 distance of 3.4069(8) Å found in the anion is typical for this class of polyiodide species, and the zigzag conformation of the extended chain is very common. − The polyiodide chains run parallel to the a -axis, and additional weak I···I interactions link chains related by 3.7502(10) Å to form loosely associated, slightly corrugated layers, with the cations occupying spaces between the layers (see Figure ).

8 Thermal ellipsoid plot (50% probability) of (a) [ tppz (H) 2 ] 2+ cation; (b) (I 2 ·I 3 - ) polyiodide anion (letters indicate symmetry operator: A, 0.5 − x , y , 0.5 − z ; B, − 0.5 − x , y , 0.5 − z ; C, x , 0.5 − y , 0.5 − z ; D, 0.5 − x , 0.5 − y , z .

9 Crystal packing of [ tppz (H) 2 ](I 2 ·I 3 ) 2 viewed down the a -axis, parallel to the polyiodide chains (origin is the upper, left, rear corner; + x is out; + y is down; + z is right).

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Über 1,1′-Dimethylferroceniumpolyiodide [(MeH4C5)2Fe]Ix mit x = 3 und 5. Darstellung und strukturelle Charakterisierung eines Triiodids (diMeFc)I3 und eines Pentaiodids (diMeFc)I5

“…Die beiden unabha È ngigen gestreckt symmetrischen Anionen der Punktsymmetrie 1 lassen sich hier jedoch vo È llig geordnet mit in der Na È he des Erwartungswertes [18] [22], Bis(phenacetin)pentaiodid [23], (g 10 -Bi-Cyclopentadienyl)-bis g 5 -p-bromobenzyl-cyclopentadienyl)-di-eisen(II,III)-pentaiodid [24] und als Strukturelement im Trisferrocenium-nonacosaiodid [2] vor, wobei sich hier die Bindungsla È ngen kaum von den dort beobachteten unterscheiden. Im Quinuclidinium-Pentaiodid fu È hrt die cis-artige Anordnung der Triiodid-Iod-Einheiten dagegen zu einer ma È anderfo È rmigen Kette [25].…”