Structure of cyclohexyl(4-pyridyl)methanol

Abstract

CI2H17NO, M r = 191.27, monoclinic, P2~/c, a = 9 . 4 1 8 ( 2 ) , b = 1 1 . 4 3 3 ( 4 ) , c = 10.364 (3) A, f l = 101.55 (3) °, V = 1093.4 (6) t~3, Z = 4 , Dm= 1.16 (by flotation), D e = 1 .162 Mg m -3, / t (Mo Ka) = 0.0686 mm -~. R = 0.077 for 1077 observed reflections. The dihedral angle between the least-squares planes of the cyclohexyl ring, which is in a slightly distorted chair conformation, and the pyridine ring is 79.9 (2) °. There is no hydrogen bonding through the alcohol group. Introduction. Bispyridinium cyclohexylcarbonyl monooximes are compounds with antidotal properties in poisoning by highly toxic organophosphorus compounds (Deljac, Bregovec, Maksimovi6, Rakin, Markov, Radi6evi6 & Binenfeld, 1979). It seemed of interest to find out whether a correlation exists between the structure and physiological activity in this group of compounds. For this purpose structure analysis of cyclohexyl(4-pyridyl)methanol (Bregovec, Deljac & Binenfeld, 1979), one of the intermediates in the preparation of the related compounds, has been performed. Intensities were collected from a prismatic crystal on an automatic Enraf-Nonius CAD-4 diffractometer with graphite-monochromated Mo Ka radiation and the 09--20 scanning technique with a 20 scan width of (0.8 + 0.2 tan 0) ° and a variable scan rate. Intensities of 1924 reflections were measured up to sin 0/4 = 0.64 A -l, 1089 of which were above the 3tr level and used in the crystal-structure analysis. Absent reflections 0k0, k :/: 2n and hOl, l :/: 2n, confirmed the space group P2~/c. Corrections were made for Lorentz and polarization factors. The structure was solved by direct methods using the program MULTAN 80 (Main, Fiske, Hull, Lessinger, Germain, Declercq & Woolfson, 1980). All non-H atoms were obtained from the E 0567-7408/82/082275-03501.00 map calculated with the 256 largest E values (E > 1.43). All subsequent calculations were performed with the XRAY system (Stewart, 1976). Isotropic leastsquares refinement of the non-H atoms gave an R of 0.176. H atoms were located from a difference map and included in the refinement with fixed isotropic temperature factors U of the corresponding C atoms increased by 0.015 A 2 and an R of 0.135 was obtained. A full-matrix refinement with anisotropic thermal parameters for the non-H and isotropic (with fixed UH) for the H atoms, but varying separately the parameters of the non-H and H atoms, gave an R of 0.106. Inspection of the structure factors revealed that five strong low-order reflections were subject to extinction and seven others to experimental errors (451,661, 761, 3,62, i,11,2, ¢~73, 193 reflections with observed/calculated structure factors as follows: 2.8/15.1, 4 .5/ 24.2, 3.7/14.6, 1.8/7.6, 5.5/12.5, 3.3/10.5, 7.7/ 13.7). Continued refinement omitting these 12 reflections reduced R to 0.077.* An improvement was evident in the bond lengths and angles involving H atoms, while the positions of the non-H atoms were practically, unchanged. The scattering factors of Cromer & Mann (1968) were used for the non-H and those of Stewart, Davidson & Simpson (1965) for the H atoms. The final atomic coordinates are listed in Table 1. All parameter shifts of the non-H atoms in the final cycle were <0. la. Calculations were performed on a Univac 1110 computer, at the University Computing Centre, Zagreb. * Lists of structure factors and anisotropic thermal parameters have been deposited with the British Library Lending Division as Supplementary Publication No. SUP 36772 (13 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England. © 1982 International Union of Crystallography 2276 C Y C L O H E X Y L ( 4 P Y R I D Y L ) M E T H A N O L Table 1. Fractional positional parameters (×104; ×103 for H) and equivalent isotropic temperature factors of the non-hydrogen atoms (× 102) computed by the expression Ueq= ~Y. l Y j Uua* a~ a i . a j The numbering of C atoms and their bonded H atoms is the same. Letters A and E denote axial and equatorial H atoms, respectively.