Ammonium Cyanate Shows N-H⋯N Hydrogen Bonding, Not N-H⋯O

Journal of the American Chemical Society

Volumn 125, Issue 47, 2003, Pages 14449-14451

  MacLean, Elizabeth J ^a   Harris, Kenneth D M ^b   Kariuki, Benson M ^b   Kitchin, Simon J ^b   Tykwinski, Rik R ^c   Swainson, Ian P ^d   Dunitz, Jack D ^e  

^a DARESBURY LABORATORY   (United Kingdom)

^b UNIVERSITY OF BIRMINGHAM   (United Kingdom)

^c UNIVERSITY OF ALBERTA   (Canada)

^d NATIONAL RESEARCH COUNCIL CANADA   (Canada)

^e ETH ZURICH   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

CRYSTAL STRUCTURE; HYDROGEN BONDS; NEUTRON DIFFRACTION; UREA;

CHEMICAL TRANSFORMATIONS; SOLID STATE REACTIONS;

AMMONIUM COMPOUNDS;

AMMONIA; AMMONIUM CYANATE; CYANIC ACID; CYANIC ACID DERIVATIVE; HYDROGEN; UNCLASSIFIED DRUG; UREA;

ARTICLE; ATOM; CRYSTAL STRUCTURE; DIFFRACTION; HYDROGEN BOND; NEUTRON; POWDER; REACTION ANALYSIS; SOLID STATE; STRUCTURE ANALYSIS;

EID: 0344875178     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja021156x     Document Type: Article

References (19)

1. Wöhler, F. Pogg. Ann. 1828, 12, 253.
2. Dunitz, J. D.; Harris, K. D. M.; Johnston, R. L.; Kariuki, B. M.; MacLean, E. J.; Psallidas, K.; Schweizer, W. B.; Tykwinski, R. R. J. Am. Chem. Soc., 1998, 120, 13 274.
3. The initial X-ray analysis was based on the assumption of the lower symmetry space group P4/n but the deviation of the derived structure from P4/ nmm was insignificant.
4. Periodic Hartree-Fock calculations with 6-31G** basis set, using the CRYSTAL95 program.
5. 4NCO: the results reported refer to analysis of the data for the deuterated material. Rietveld refinement of the synchrotron X-ray powder diffracfion data was carried out using the program MPROF (A. D. Murray, A. N. Fitch, University College London, 1989).
6. Although there is usually no difficulty about localizing H atoms in X-ray analysis based on single-crystal diffraction data (apart from the characteristic systematic contraction of apparent X-H bond distances), the reduction of information inherent in powder diffraction pattems can make H atom localization from analysis of X-ray powder diffraction data much more problematic.
7. Periodic Hartree-Fock calculations were carried out using the CRYSTAL95 and CRYSTAL98 packages for a range of different basis sets and a range of values of other parameters controlling the calculation (Posada, A.; Johnston, R. L.; Harris, K. D. M., unpublished results), In some cases, a lower energy was obtained for N-H⋯O hydrogen bonding, in others for N-H⋯N. No geometry optimization was carried out, and the positions of all non-hydrogen atoms were fixed at those in the crystal structure. For some calculation conditions, the energetic ordering of the N-H ⋯O and N-H⋯N structures was different depending on whether the coordinates of the non-hydrogen atoms were those determined at 14 K (from the neutron powder diffraction data presented here) or at ambient temperature (reported previously [2] from X-ray powder diffraction data). A more detailed appraisal of computational approaches for investigating this issue is required.
8. The restrained values were as follows: Situation 1: O-C, 1.174 Å, C-N 1.192 Å: Situation 2: O-C, 1.256 Å, C-N, 1.181 Å. The actual bond lengths obtained in the refinements remained close to these restrained values.
9. wp = 13.71%. The Rietveld difference plots for these refinement calculations are included in the Supporting Information.
10. 4, was about 77%.
11. 1H and the strong incoherent neutron scattering of the latter.
12. 4NCO samples were collected at several temperatures (14, 77, 135, 210, 245, 288 K) over the 2θ range 5° to 117°, with a step size of 0.1° and a total data collection time of about 4 h at each temperature. Rietveld refinement of the neutron powder diffraction data was carried out using the program GSAS (Larson, A. C., Von Dreele, R. B., Los Alamos Laboratory Report No. LA-UR-86-748, 1987).
13. -15).
14. This conclusion was confirmed by Rietveld refinement calculations for a disorder model comprising x % of situation A and (100-x) % of situation B. In such calculations, x refines, within experimental errors, to a value of zero.
15. Rietveld refinement for situation B was also carried out for the lower space group P4/n but the resulting deviation of the H/D atoms from the mirror planes was insignificant. The description in space group P4/nmm is therefore preferred.
16. Crystal data at higher temperatures (77-288 K) are given in Supporting Tables 2-6.
17. 15N NMR chemical shift for the cyanate N without significant change in the isotropic chemical shift for the ammonium N. This may be explained by the fact that hydrogen bonding has a decreased inductive effect on the acceptor N atom of the cyanate anion as the crystal expands. As a consequence, this atom becomes systematically more deshielded as the hydrogen bond distance increases.
18. For a recent example see Dunitz, J. D. Chem. Commun. 1999, 2547.
19. Britton, D.; Dunitz, J. D. Acta Crystallogr. 1965, 18, 424.