2-(4-Iodophenoxy)acetamide

The molecule of the title compound, C8H8INO2, amide-typical resonance shortens the nominal C—N single bond to 1.322 (7) Å. In the crystal, hydrogen bonds involving both nitrogen-bound H atoms as well as C—H⋯O contacts connect the molecules into double layers approximately perpendicular to the crystallographic b axis. No π-stacking is apparent in the crystal structure.

The molecule of the title compound, C 8 H 8 INO 2 , amide-typical resonance shortens the nominal C-N single bond to 1.322 (7) Å . In the crystal, hydrogen bonds involving both nitrogen-bound H atoms as well as C-HÁ Á ÁO contacts connect the molecules into double layers approximately perpendicular to the crystallographic b axis. No -stacking is apparent in the crystal structure.

Comment
Unlike carboxylic acids, their pertaining amides have not been studied extensively as ligands in coordination chemistry.
Owing to their versatility in terms of denticity, keto-enol tautomerism as well as their possible use as neutral -or upon deprotonation -anionic ligands we set out to investigate the coordination behaviour of substituted acetamide derivatives to elucidate the rules guiding the formation of complex compounds. To enable comparative studies with envisioned reaction products, we determined the molecular and crystal structure of the title compound. So far, only the structures of 2-(4nitrophenoxy)acetamide (Lakshmi Rao et al., 1987) and of 2-(4-chloro-2-methylphenoxy)acetamide  have been discussed as examples of phenoxy-substituted derivatives of acetamide.
The C-N single bond is shortened to 1.322 (7) Å due to the amide-typical resonance. This value is in good agreement with other derivatives of acetamide whose crystallographic data has been deposited with the Cambridge Structural Database (Allen, 2002) and whose ketonic oxygen atom is not involved in donor action towards transition metals. Intracyclic C-C-C angles hardly deviate from the ideal value of 120 °. The least-squares planes defined by the acetamide moiety and the oxygen atom of the phenoxy-derivative substituent on the one hand and the carbon atoms of the carbocycle on the other hand intersect at an angle of 24.91 (29) ° ( Fig. 1 and Fig. 2).
In the crystal structure, both nitrogen-bonded H atoms participate in hydrogen bonds which invariably have the carbonyl oxygen atom as acceptor. While one of the H atoms of the amino group connects the molecules to centrosymmetric dimeric subunits, the other H atom of the NH 2 group connects these dimers to chains along [1 0 0]. Additionally, one of the hydrogen atoms of the methylene group forms a C-H···O contact whose range falls by more than 0.2 Å below the sum of van-der-Waals radii of the respective atoms. Again, the double-bonded O atom acts as acceptor. In terms of graph-set analysis (Etter et al., 1990;Bernstein et al., 1995), the hydrogen bonds stemming from the amino group can be described by a C 1 1 (4)R 2 2 (8) descriptor on the unitary level while the C-H···O contacts necessitate a R 2 2 (4) descriptor on the same level. In total, the molecules are connected to double layers approximately perpendicular to the crystallographic b-axis (Fig. 3). No π-stacking is apparent in the crystal structure.
The packing of the compound is shown in Figure 4.

Experimental
The compound was prepared upon reacting 2-phenoxyacetamide with tert-butyl hypochlorite and iodine according to a published procedure (Glover et al., 1973).
supplementary materials sup-2 Refinement Carbon-bound H-atoms were placed in calculated positions (C-H 0.99 Å for the methylene group and C-H 0.95 Å for aromatic carbon atoms) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U eq (C).