Crystal structure of 2-methyl-pyridine-N-oxide, C6H7NO

Abstract

C6H7NO, orthorhombic, Pbca (no. 61), a = 5.7327(6) A, b = 13.347(1) A, c = 14.593(2) A, V = 1116.6 A, Z = 8, R(F) = 0.060, wRref(F ) = 0.122, T = 200 K. Source of material The compound was obtained commercially (Aldrich). Crystals suitable for the X-ray diffraction study were taken directly from the provided batch andmounted as quickly as possible to account for the lowmelting point as well as the hydrophilicity of the compound. Experimental details Hydrogen atoms bound to aromatic carbon atoms were placed in calculated positions with d(C—H) = 0.95 A and were included in the refinement in the ridingmodel approximationwithU(H) set to 1.2 Ueq(C). The hydrogen atoms of the methyl group were allowed to rotate with a fixed angle around the C—Cbond to best fit the experimental electron density (HFIX 137 [1]). Discussion The coordination chemistry of picolyl oxides is vastly unexplored. To allow for comparative studies of bond lengths and angles in envisioned coordination compounds, we determined the molecular and crystal structure of the title compound. Structural analyses for other pyridine-derived N-oxides are apparent in the literature [2,3]. The molecule shows non-crystallographic Cs symmetry. The length of the N—O bond is in good agreement with other aromatic N-oxides whose crystal structural data has been deposited with the Cambridge Structural Database [4]. In the crystal structure, C–H)))O contacts whose range falls by 0.3 A below the sum of van-der-Waals radii are present. These stem from the hydrogen atom in ortho-position to the intracyclic nitrogen atom and give rise to the formation of centrosymmetric dimers. In terms of graph-set analysis [5,6], the descriptor for these contacts is R2 2 8 ( ) on the unitary level. The lack of further pronounced intermolecular contacts is in good agreement with the low melting point of the title compound. --Stacking is not a prominent feature in the crystal structure, with the shortest intercentroid distance between two aromatic systems found at 4.921(1) A. Z. Kristallogr. NCS 226 (2011) 603-604 / DOI 10.1524/ncrs.2011.0271 603 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colourless block, size 0.404 0.409 0.484 mm Wavelength: Mo K+ radiation (0.71073 A) .: 0.90 cm Diffractometer, scan mode: Bruker APEX-II CCD, #/% 2,max: 55.98° N(hkl)measured, N(hkl)unique: 8338, 1313 Criterion for Iobs, N(hkl)gt: Iobs > 2 )(Iobs), 1034 N(param)refined: 74 Programs: SIR97 [7], SHELXL-97 [1], ORTEP-3 [8], Mercury [9], PLATON [10] Table 1. Data collection and handling. H(2) 8c 0.2934 0.1815 0.1910 0.046 H(3) 8c 0.5410 0.3116 0.1491 0.046 H(4) 8c 0.8848 0.2741 0.0693 0.044 H(5) 8c 0.9744 0.1090 0.0353 0.041 H(6A) 8c 0.2847 &0.0514 0.1038 0.067 H(6B) 8c 0.1995 0.0041 0.1951 0.067 H(6C) 8c 0.4248 &0.0666 0.1977 0.067 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso _____________ * Correspondence author (e-mail: richard.betz@webmail.co.za) O(1) 8c 0.7427(3) &0.04359(8) 0.07185(9) 0.0506(9) 0.0219(5) 0.0640(8) 0.0028(5) 0.0125(7) &0.0038(5) N(1) 8c 0.6880(3) 0.04874(9) 0.09229(9) 0.0336(8) 0.0237(6) 0.0358(7) 0.0012(6) 0.0008(6) 0.0000(5) C(1) 8c 0.4859(3) 0.0683(1) 0.1378(1) 0.032(1) 0.0343(8) 0.0298(7) &0.0020(7) 0.0009(6) &0.0006(6) C(2) 8c 0.4334(3) 0.1669(1) 0.1588(1) 0.036(1) 0.0428(9) 0.0352(8) 0.0075(8) 0.0011(7) &0.0061(7) Table 3. Atomic coordinates and displacement parameters (in A). Atom Site x y z U11 U22 U33 U12 U13 U23 Unauthenticated Download Date | 4/17/16 7:56 AM