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Acta Cryst. (1997). C53, 1909-1911

Tris(l-phenacyl-2-pyridone) Hydroxonium Tetrafluoroborate, a Hydrogen-Bonded Complex
S . G . ZHUKOV, a V . B . RYBAKOV,a E . V . BABAEV, K. A . PASESHNICHENKOa AND H . SCHENKb
aDepartment
a

of Chemistry, Moscow State University, 119899 Moscow, Russian Federation, and bLaboratory for Crystallography, Amsterdam University, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands. E-mail: ksenia @ biocryst.phys. msu.su
(Received 15 May 1997; accepted 16 July 1997)

Abstract The hydrolytic cleavage of 2-phenyloxazolo[3,2-a]pyridinium tetrafluoroborate results in the formation of the title tris(l-phenacyl-2-pyridone) hydroxonium tetrafluoroborate complex, 3C 13 H 11 NO 2 .H 3 O + .BF 4 - . The structure is built up from hydrogen-bonded cations and disordered BF4~ anions. The strong hydrogen bonding causes considerable redistribution of electron density in the pyridone moiety. Comment Recently, it was found that mesoionic 2-oxo-3-benzoyloxazolo[3,2-a]pyridine can be transformed to oxazolo[3,2-a]pyridinium tetrafluoroborate by the action of H 2 SO 4 and HBF4 (Babaev & Orlova, 1997). Having attempted to confirm the structure of this compound, we discovered that prolonged standing of the reaction mixture (one week at room temperature) resulted in the unexpected formation of N-phenacyl-2-pyridone, (I). Although the ring opening of the former compound is known to occur by the action of alkali (Pauls
Acta Crystallographica Section C ISSN 0108-2701 © 1997


1910

3C13HnNO2.H3Cr.BF4r found any examples of such compounds with the H3O+ cation coordinated by three neutral organic molecules in a search of the Cambridge Structural Database (Allen & Kennard, 1993). Experimental
Single crystals of the title compound were obtained by evaporation of a water solution of 2-phenyloxazolo[3,2-a]pyridinium tetrafluoroborate. Chemical analysis: found C 62.75, H 4.40%; C39H36BF4N3O7 requires C 62.83, H 4.46%.

& Kroehnke, 1976), no data on the extremely mild hydrolysis by the action of water have been reported, The formation of pyridone is the result of hydrolytic cleavage of the oxazolium fragment by two molecules of water (see scheme below).

The first water molecule causes ring opening and formation of pyridone, while the second serves as the acceptor of a proton. The N-phenacyl-2-pyridone molecule forms a strong hydrogen bond via the pyridone 0 atom to the H3O+ cation positioned on the 3 axis [02- · H I 1.50 (2), 02 - · O l 2.524 (2) A and O2- · HI -- 0 1 171 (2)°]. As a result of hydrogen bonding, the C2--0 2 bond in the present structure is 0.02 A longer than the longest in known structures containing the Nalkylated pyridone moiety (Nawata, Matsuura, Ando & Iitaka, 1990; Hsu & Craven, 1974; Schwalbe & Saenger, 1973). The other bond lengths and angles are ordinary for compounds of this type. In the difference Fourier maps, no sign of proton transfer from H3O+ to the pyridone O atom was found. The BF4~ anion is orientationally disordered over two sets of sites and does not form any considerably short contacts with the hydrogen-bonded complex cation; the shortest F- · H(pyridone) distances are 2.40 A, i.e. 0.2 A shorter than the sum of the van der Waals radii. We have not

Crystal data 3Ci3Hi,NO2.H3O+.BFr Mr = 745.52 Trigonal R3 a = 14.020 (2) A c = 33.005 (5) A V= 5618.3(14) A3 Z=6 Dx = 1.322 Mg m~ 3 Dm not measured Data collection Enraf-Nonius CAD-4 diffractometer u scans Absorption correction: none 2724 measured reflections 2724 independent reflections 1355 reflections with / > 2a(I) Refinement Refinement on F2 R[F2 > 2a(F2)] = 0.053 wR(F2) = 0.130 S= 1.027 2724 reflections 225 parameters All H atoms refined w = V[a2(F2) + (0.051P)2] where P = (F2 + 2F2)/3 (A/a)max = 0.012 Apmitx = 0.151 e A~ 3 Apmin = -0.15 4 e A" 3 Extinction correction: SHELXL93 Extinction coefficient: 0.0011 (2) Scattering factors from International Tables for Crystallography (Vol. C) Mo Ka radiation A = 0.7107 A Cell parameters from 22 reflections 9 = 15.4-17.0° n = 0.104 mm" 1 T=293(2) K Irregular 0.55 x 0.40 x 0.33 mm Colourless

6»max = 26.9° h = 0 -- 15 * k = 0 -- 15 » / = --41 -- 42 » 2 standard reflections frequency: 150 min intensity decay: none

Tabl e 1. Fractional atomic coordinates and equivalent isotropic displacement parameters (A2) Ueq = (l/DEiEjUVafaTm.sij. x
01 Nl 02 03 C2 C3 C4 C5 C6 C7 C8 C9 1/3 0.55916(14) 0.44653(13) 0.36388(13) 0.5147(2) 0.5497(2) 0.6222(2) 0.6657(3) 0.6330(2) 0.5208(2) 0.4073(2) 0.3530(2)

y
2/3 0.55407(14) 0.57930(12) 0.39143(13) 0.6164(2) 0.7171(2) 0.7485(2) 0.6831(3) 0.5866(2) 0.4469(2) 0.3640(2) 0.2508(2)

z
0.02200(9) 0.08376(5) 0.04134(5) 0.10647(5) 0.07057(7) 0.09097(9) 0.12176(8) 0.13395(9) 0.11477(7) 0.06510(8) 0.08081(7) 0.06390(7)

U

tq

Fig. 1. The formula unit of tris( 1-phenacy1-2-pyridone) hydroxonium tetrafiuoroborate showing 25 % probability displacement ellipsoids.

0.0633(8) 0.0502(5) 0.0603(5) 0.0657(5) 0.0534(6) 0.0659(7) 0.0747(8) 0.0742(8) 0.0612(7) 0.0512(6) 0.0493(6) 0.0518(6)


S. G. ZHUKOV et al.
CIO Cl l C12 C13 C14 Fl f 0.4024(2) 0.3484(3) 0.2450(3) 0.1952(3) 0.2491(2) 0.5770(6) 0.2193(2) 0.1142(2) 0.0404(3) 0.0699(3) 0.1753(2) 0.3274(8) 0.03446(7) 0.01876(9) 0.03236(10) 0.06187(11) 0.07741(9) 0.1594(3) 0.0590(7) 0.0704(8) 0.0810(9) 0.0825(9) 0.0681(7) 0.236(6)

1911

Fli t F2f
F21t Bl

0.5684(6) 2/3
2/3 2/3

0.3173(5) 1/3
1/3 1/3

0.1372(3) 0.1069(3)
0.1905(4) 0.1498(2)

0.145(5) 0.145(4)
0.228(9) 0.083(2 )

f Site occupancy = 0.580 (12).

% Site occupancy = 0.420 (12).

Table 2. Selected geometric parameters (A, °)
Nl -- C6 Nl--C 2 Nl--C 7 O2--C2 C6--Nl--C2 C6--Nl--C 7 C2--Nl--C 7 O2--C2--Nl O2--C2--C3 C6--Nl--C7--C8 C2--Nl--C7--C 8 Nl--C7--C8--O3 1.362(3) 1.374(3) 1.455(3) 1.272(2) 122.4(2) 119.4(2) 118.1(2) 117.8(2) 125.8(2) 101.1(2) -75.6(2 ) -2.2(3 ) C2--C3 C3--C4 C4--C5 C5--C6 Nl--C2--C 3 C4--C3--C2 C3--C4--C5 C6--C5--C4 C5--C6--Nl Nl--C7--C8--C9 03--C8--C9--C14 03--C8--C9--CIO 1.412(3) 1.345(4) 1.392(4) 1.349(4) 116.3(2) 121.0(3) 120.7(3) 118.9(3) 120.6(3) 177.7(2) 1.1(3) 179.8(2)

Data collection: CAD-4 Software (Enraf-Nonius, 1989). Cell refinement: CAD-4 Software. Data reduction: SDPPlus (Frenz, 1985). Program(s) used to solve structure: SHELXS96 (Sheldrick, 1996). Program(s) used to refine structure: SHELXL93 (Sheldrick, 1993). Molecular graphics: ORTEX (McArdle, 1995). Software used to prepare material for publication: SHELXL93. This work has been supported by The Netherlands Organization for Fundamental Research (NWO). The authors are also indebted to the Russian Foundation for Basic Research for covering the licence fee for the use of the Cambridge Structural Database (project 96-0789187). Supplementary data for this paper are available from the IUCr electronic archives (Reference: NA1311). Services for accessing these data are described at the back of the journal. A packing diagram has also been deposited.

References Allen, F. H. & Kennard, O. (1993). Chem. Des. Autom. News, 8, 31-37 . Babaev, E. V. & Orlova, I. A. (1997). Khim. Geterotsikl. Soedin. pp. 569-571 . Enraf-Nonius (1989). CAD-4 Software. Version 5.0. Enraf-Nonius, Delft, The Netherlands. Frenz, B . A. (1985). Enraf-Nonius SDP-Plus Structure Determination Package. Version 3.0. Enraf--Nonius, Delft, The Netherlands. Hsu, I.-N. & Craven, B. M. (1974). Ada Cryst. B30, 998-1001 . McArdle, P. (1995). J. Appl. Cryst. 28 , 65 . Nawata, Y., Matsuura, I., Ando, K. & Iitaka, Y. (1990). Acta Cryst. C46, 515-517. Pauls, H. & Kroehnke, F. (1976). Chem. Ber. 109, 3653-3660. Schwalbe, C. H. & Saenger, W. (1973). Acta Cryst. B29, 61-69 . Sheldrick, G. M. (1993). SHELXL93. Program for the Refinement of Crystal Structures. University of Gottingen, Germany. Sheldrick, G. M. (1996). SHELXS96. Program for the Solution of Crystal Structures. University of Gottingen, Germany. © 1997 International Union of Crystallography Printed in Great Britain - all rights reserved