Hydrogen bond studies. XX. The crystal structure of ammonium formate

Abstract

The crystal structure of ammonium formate has been determined at room temperature from threedimensional single-crystal X-ray data. Two HCOONH4 units crystallize in a monoclinic unit cell of space group Pc and dimensions a=3.814, b=4.679, c=9.112A,, and B=91"17 °. The structure was refined by the method of least squares with allowance for anisotropic thermal motion, and gave a final discrepancy index of 0-067. The ammonium ion forms four hydrogen bonds N+-H • • • O-of length 2-81-2.89 A,, in an approximately tetrahedral arrangement. In the three-dimensional hydrogen-bonded network thus formed each oxygen atom accepts two hydrogen bonds. The dimensions of the formate ion are: bond lengths, C-O = 1-237 and 1-246 A,; bond angle, O-C-O = 126.3 °.

Synthesis, microwave spectra, x-ray structure, and high-level theoretical calculations for formamidinium formate

“…Both are symmetrical and perfectly planar. The dimensions of the formate ion are similar to those occurring in ammonium formate 30 (Table 3) are well within the normal range for strong NH-O hydrogen bonds with the former being slightly stronger and more accurately linear. The orientation of ions within each layer is consistent but this is reversed in alternate layers resulting in an overall centrosymmetric structure.…”

Redetermination of the crystal structure of ammonium formiate at 200 K, CH5NO2

“…C-O bond lengths of 1.2496(12) and 1.2502(13) Å, respectively, are nearly identicaldue to resonancestabilization of thecarboxylate. These values are, therefore,found to be slightly longer thanthe correspondingb ond lengthsa tr oomt emperature fort his compound that were reported to be around 1.23-1.24 Å [2]. All of the nitrogen-bound hydrogen atomsp articipate in hydrogen bonds with both oxygen atomsofthe formiate anion acting as acceptors.…”

“…To allow for the comparison of the influence of hydrogen bonding on structural parameters, the ammonium salt of this acid was chosen as astarting point. Although the structure of the latter compound has been determined earlier, data is only availableatroomtemperature [2]. As molecular and crystal structures of target molecules are to be determined at low temperature, the structure of the title compound was re-determined to enable comparisons of individual metrical parameters throughout the whole series.…”

Interanionic(−)O−H⋅⋅⋅O(−) Interactions: A Solid-State and Computational Study of the Ring and Chain Motifs

“…A recent CSD survey has shown that the RING motif is observed in 95 % of the structures of neutral carboxylic and polycarboxylic molecules. [22] A notable exception is acetic acid which forms the CHAIN motif in the solid state, [23] although it has been demonstrated by theoretical calculations that the acetic acid RING is favoured over CHAIN by approximately 3 kcal mol À1 . [24a] These differences were explained by invoking the contribution of other weak intermolecular interactions in the solid state with respect to the structure of the isolated dimers in a vacuum.…”