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Crystallography Reports, Vol. 46, No. 3, 2001, pp. 385­388. Translated from Kristallografiya, Vol. 46, No. 3, 2001, pp. 435­438. Original Russian Text Copyright © 2001 by Rybakov, Zhukov, Babaev, Sonneveld.

STRUCTURE OF ORGANIC COMPOUNDS

X-ray Mapping in Heterocyclic Design: IV. Crystal Structure Determination of 3-(p-Nitrobenzoyl)-2-Oxooxazolo[3,2-a]pyridine from Powder Diffraction Data
V. B. Rybakov*, S. G. Zhukov*, E. V. Babaev*, and E. J. Sonneveld**
* Faculty of Chemistry, Moscow State University, Vorob'evy gory, Moscow, 119899 Russia e-mail: rybakov@biocryst.phys.msu.su ** Laboratory of Crystallography, Faculty of Chemistry, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, Netherlands
Received May 15, 2000

Abstract--The structure of 3-(p-nitrobenzoyl)-2-oxooxazolo[3,2-a]pyridine is determined by the powder diffraction technique. The crystals are monoclinic, a = 13.642(2) å, b = 22.278(3) å, c = 3.917(1) å, = 90.63(2)°, Z = 4, and space group P21/n. The structure is solved by a modified Monte Carlo method and refined by the Reitveld method. The six-membered heterocycle is characterized by the alternation of partially single and partially double bonds. The system of two conjugated heterocycles is planar and forms a dihedral angle of 46.1(1)° with the plane of the phenyl ring. The nitro group is virtually coplanar with the phenyl fragment. An extensive system of intramolecular and intermolecular contacts involving hydrogen, oxygen, and nitrogen atoms is observed in the crystal. © 2001 MAIK "Nauka / Interperiodica".

INTRODUCTION This paper continues a series of structural investigations of the heterocyclic compounds that are able to enter readily into reactions of ring transformations and various chemical rearrangements. Our previous studies in this field were reported in [1­7]. The crystal structure of the mesoionic compound 3-benzoyl-2-oxooxazolo[3,2-a]pyridine was determined by X-ray diffraction in [8]. In the present work, we concentrated on the structural study of its analogue, namely, 3-(p-nitroben-

zoyl)-2-oxooxazolo[3,2-a]pyridine. There are no data on its structure in the Cambridge Structural Database [9]. The compound was prepared according to the procedure described earlier in [10]. Our interest in the structure and properties of this subclass of mesoionic heterocycles is due to, first, the unusual (ilide) structural type of these heterocycles [8] and, second, the possibility of readily opening the oxazolone ring and its transforming into the oxazolium ring [11] according to the following scheme:

O+ N O I O R
­

H2O

O N O II R

H+ ­H2O

O+ N III R

R = aryl

Earlier [2, 3], we performed the X-ray structure analysis of compounds II and III (R = C6H5), that is, both products of hydrolysis of the mesoionic system I [2]. Thus, the crystal structure determination of compound I with R = p-NO2-C6H4 (Ia) as a precursor of compounds II and III provides one more example of the principle of the X-ray mapping of reactions [5­7].

EXPERIMENTAL The diffraction experiment was performed using an evacuated Enraf­Nonius Guinier­Johansson FR552 camera (CuK1, quartz monochromator). The intensities of the X-ray spectrum were measured with an LS18 densitometer in 0.01° steps in the 2 range 4°­86° and the hkl range 0 h 12; 0 k 19, ­3 l 3. The unit

1063-7745/01/4603-0385$21.00 © 2001 MAIK "Nauka / Interperiodica"


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Table 1. Atomic coordinates (â 104) and isotropic thermal parameters Uiso (å2 â 103) Atom C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) N(1) O(1) O(2) C(14) N(12) O(3) O(12A) O(12B) H(3) H(4) H(5) H(6) H(10) H(11) H(13) H(14) x 4146(10) 4264(10) 5684(10) 6651(10) 7074(10) 6639(10) 5644(10) 3666(10) 2604(10) 2131(10) 1106(10) 648(10) 1065(10) 5251(8) 5084(10) 3575(10) 2093(10) ­ 476(10) 3904(6) ­ 767(6) ­ 782(6) 5338 7048 7855 6908 2526 740 685 2457 y 3112(6) 3699(6) 4169(6) 4060(6) 3476(6) 3018(6) 3155(6) 4217(6) 4109(6) 4565(6) 4525(6) 4004(6) 3515(6) 3692(6) 2759(6) 2802(6) 3577(6) 3949(6) 4705(6) 4373(6) 3474(5) 4585 4405 3421 2571 4971 4897 3107 3210 z 5472(15) 4050(15) 999(17) ­ 29(15) 731(15) 2317(15) 3446(15) 3267(15) 4369(15) 6060(15) 6786(15) 5890(15) 4150(15) 2745(12) 5105(15) 6992(15) 3478(15) 6708(15) 2475(11) Uiso 49(6) 49(6) 49(6) 51(7) 51(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7) 49(7)

The structure was solved by the modified Monte Carlo method [14, 15] with the use of the known molecular fragments. The full-profile refinement of the structure was performed by the Rietveld method with the MRIA program [16]. The reflection profiles were described by the function proposed in [17], and the background was approximated by the Chebyshev polynomials of the fifth order. The texture parameters were refined within the March­Dollase model [18] in the [001] direction. The procedure of the structural investigation of Ia is described in more detail in [19]. The final R factors of the full-matrix refinement were Rp = 0.053, Rb = 0.155, and Re = 0.024, where Rp = I obs ­ I calcd / I 0 , Rb = I obs ­ I calcd / I obs ­ Bckgr , Re = I obs / I obs , Iobs is the observed intensity, and Icalcd is the calculated intensity; the 2 criterion was equal to 6.9. The atomic coordinates are listed in Table 1 (the positions of the H atoms were calculated from geometric considerations; in the course of the refinement, the H atoms were rigidly bound to the corresponding carbon atoms). The schematic drawing of the molecule (see figure) was obtained with the PLUTON96 program [20]. The atomic numbering in Ia is the same as that in [8] for convenient comparison of the geometric parameters of the molecules. RESULTS AND DISCUSSION The binuclear fragment of molecule Ia is planar, and its structure is essentially the same as that of its analogue Ib (R = C6H5) [8]; specifically, the bond lengths in the C(3)­C(4)­C(5)­C(6) fragment of the six-membered heterocycle alternate, the lengths of the C(1)­O(1) endocyclic bonds in the two structures completely coincide, and the O(1)­C(7) bond in Ia is only 0.05 å longer than that in Ib. This structure suggests that the six-membered fragment of the mesoionic bicyclic molecule can be represented by the pyridine-like (butadiene) structure to a greater extent than by the delocalized pyridine ring. From structural considerations, it follows that the positive charge is distributed over the N(1)­C(7)­O(1) bonds and the pyridine fragment of the molecule is not involved in delocalization. According to the above scheme, the C(1)­C(2) bond should be of the double type, but it is actually substantially longer [1.43(2) å]. On the other hand, the length of the C(1)­O(2) exocyclic bond [1.20(2) å] corresponds to the double bond. Therefore, the geometry of the O(2)­C(1)­C(2)­C(8)­O(3) fragment corresponds to a combination of two carbonyl groups connected through the C(2) atom without significant delocalization. Possibly, this indicates that the negative charge is localized at the C(2) atom. The molecular structures under comparison considerably differ in the arrangement of the phenyl rings with respect to the heterocyclic nucleus. The angles
CRYSTALLOGRAPHY REPORTS Vol. 46 No. 3 2001













8055(11) 109(11) 5695(15) 525 ­ 1328 ­ 169 2980 6841 8106 3517 2242 67(11) 51* 51* 51* 51* 51* 51* 51* 51*

* The thermal parameter was fixed and not refined.

cell parameters were determined by the ITO indexing program [13], and the space group was determined from the systematic absences of reflections. Crystals Ia (C14H8N2O5) are monoclinic, a = 13.642(2) å, b = 22.278(3) å, c = 3.917(1) å, = 90.63(2)°, V = 1190.4(4) å3 , dcalcd = 1.653 g/cm3 , µ(Cu) = 10.8 cm­1, Z = 4, and space group P21/n.


X-RAY MAPPING IN HETEROCYCLIC DESIGN: IV.

387

1.46(2)

1.34(2)

C(6)
1.45(2)

1.34(2)
1.34(2)

1.51(2)

C(5)
1.40(2)

O(1) C(7)
1 45(2)

1.20(2)

1.40(2)

1.44(2)

C(4)

N(1)

1.43(2)

C(1)

O(2)

C(2)
1 54(2)
1.42(2)

C(3)
1.18(2)

1 44(2)

C(14)

C(13)
1.41(2)

C(8)

C(9)
1.38(2)

O(12B)
1 57(2)
1.15(2)

O(3)

1 43(2)

C(12)
1.36(2)

1.20(2)

C(10)

N(12) O(12A)

C(11)

Structure of the molecule studied and the atomic numbering.

between the planes of the phenyl ring and the oxazolo[3,2-a]pyridine bicyclic fragment are 66.8(2)° and 46.1(2)° in molecules Ib [8] and Ia, respectively. The pronounced decrease in the angle of ring rotation in the molecule studied is most likely due to the packing effects caused by the nitro group in the para position of the phenyl fragment. The nitro group itself is
Table 2. Parameters of the interatomic contacts* [19] D­H C(3)­H(3) C(13)­H(13) C(11)­H(11) C(10)­H(10) C(14)­H(14) C(3)­H(3) C(4)­H(4) C(11)­H(11) C(11)­H(11) C(10)­H(10) C(14)­H(14) C(4)­H(4) C(5)­H(5) C(5)­H(5) C(5)­H(5) C(5)­H(5) d(D­H) 1.06(9) 1.07(9) 1.10(8) 1.10(9) 1.08(8) 1.06(9) 1.07(8) 1.10(8) 1.10(8) 1.10(9) 1.08(8) 1.07(8) 1.13(8) 1.13(8) 1.13(8) 1.13(8) d(D···A) 2.77(2) 2.60(2) 2.63(2) 2.83(1) 2.98(2) 2.91(2) 3.01(2) 3.13(2) 3.22(2) 3.48(1) 3.69(2) 3.68(2) 3.86(2) 3.72(2) 3.55(1) 3.49(1)

virtually coplanar with the phenyl ring: the rotation angle is 1(1)°. A system of intramolecular and intermolecular C-H···O and C­H···N contacts is formed in the crystal (Table 2). These contacts were calculated with the PARST95 program [21].

d(H···A) 2.13(8) 2.33(8) 2.36(8) 2.62(7) 2.56(7) 2.23(8) 2.41(9) 2.91(7) 2.22(7) 2.94(7) 2.73(7) 2.99(8) 2.85(8) 2.92(9) 2.48(7) 2.94(6)

DHA 117(6) 92(5) 91(5) 89(4) 103(5) 120(5) 114(5) 91(4) 150(5) 111(4) 149(4) 122(5) 148(5) 127(5) 156(5) 110(4)

A (symmetry operation) O(3) (x; y; z) O(12B) (x; y; z) O(12A) (x; y; z) O(3) (x; y; z) O(2) (x; y; z) O(3) (1 ­ x;1 ­ y; ­ z) O(3) (1 ­ x;1 ­ y; ­ z) O(12A) (­ x;1 ­ y; 1 ­ z) O(12A) (­ x;1 ­ y; 2 ­ z) O(3) (x; y; 1 + z) O(2) (x; y; z ­ 1) O(12A) (1 + x; y; z ­ 1) N(12) (1 + x; y; z ­ 1) O(12A) (1 + x; y; z ­ 1) O(12B) (1 + x; y; z ­ 1) O(12B) (1 + x; y; z)

* D is a donor, A is an acceptor, and H is a hydrogen atom (the d distances and angles are given in å and degrees, respectively). CRYSTALLOGRAPHY REPORTS Vol. 46 No. 3 2001


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ACKNOWLEDGMENTS This study was supported by the Netherlands Society of Basic Research (NWO). The synthetic part of this work was supported by the Russian Foundation for Basic Research, project no. 99-03-33076. We also acknowledge the support of the RFBR in the payment of the license for using the Cambridge Structural Database, project no. 99-07-90133. REFERENCES
1. E. V. Babaev, A. V. Efimov, S. G. Zhukov, and V. B. Rybakov, Khim. Geterotsikl. Soedin., No. 7, 983 (1998). 2. E. V. Babaev, S. V. Bozhenko, D. A. Maiboroda, et al., Bull. Soc. Chim. Belg. 106 (11), 631 (1997). 3. S. G. Zhukov, V. B. Rybakov, E. V. Babaev, et al., Acta Crystallogr., Sect. C: Cryst. Struct. Commun. C53, 1909 (1997). 4. E. V. Babaev, S. V. Bozhenko, S. G. Zhukov, and V. B. Rybakov, Khim. Geterotsikl. Soedin., No. 8, 1105 (1997). 5. V. B. Rybakov, S. G. Zhukov, E. V. Babaev, et al., Kristallografiya 44 (6), 1067 (1999) [Crystallogr. Rep. 44, 997 (1999)]. 6. V. B. Rybakov, S. G. Zhukov, E. V. Babaev, et al., Kristallografiya 45 (1), 108 (2000) [Crystallogr. Rep. 45, 103 (2000)].

7. V. B. Rybakov, S. G. Zhukov, E. V. Babaev, et al., Kristallografiya 45 (2), 292 (2000) [Crystallogr. Rep. 45, 261 (2000)]. 8. S. G. Zhukov, E. V. Babaev, V. V. Chernyshev, et al., Z. Kristallogr. 215, 306 (2000). 9. F. H. Allen and O. Kennard, Chem. Des. Autom. News 8 (1), 31 (1993). 10. G. V. Boyd and P. H. Wright, J. Chem. Soc. C, No. 10, 1486 (1970). 11. E. V. Babaev and I. A. Orlova, Khim. Geterotsikl. Soedin., No. 4, 569 (1997). 12. E. V. Babaev, V. B. Rybakov, S. G. Zhukov, and I. A. Orlova, Khim. Geterotsikl. Soedin., No. 4, 542 (1999). 13. J. W. Visser, J. Appl. Crystallogr. 2, 89 (1969). 14. K. D. M. Harris, M. Tremayne, P. Lightfoot, and P. G. Bruce, J. Am. Chem. Soc. 116, 3543 (1994). 15. Yu. G. Andreev, P. Lightfoot, and P. G. Bruce, J. Appl. Crystallogr. 30, 294 (1997). 16. V. B. Zlokazov and V. V. Chernyshev, J. Appl. Crystallogr. 25, 447 (1992). 17. H. Toraya, J. Appl. Crystallogr. 19, 440 (1986). 18. W. A. Dollase, J. Appl. Crystallogr. 19, 267 (1986). 19. S. G. Zhukov, V. V. Chernyshev, E. V. Babaev, et al., Z. Kristallogr. 216 (1), 5 (2001). 20. A. L. Spek, PLUTON96: Molecular Graphics Program (Univ. of Utrecht, Netherlands, 1996). 21. M. Nardelli, J. Appl. Crystallogr. 28, 659 (1995).

Translated by I. Polyakova

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2001