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Structure and spectroscopic behaviour of the solid adduct of 3-methylpyridine with 2,6-dichloro-4-nitrophenol
177
Journal of Molecular Structure, 291(1993) 177- 184 0022-2860/93/%06.000 1993 - Elsevier Science Publishers B.V. All rights reserved
Structure and spectroscopic behaviour of the solid adduct of 3-methylpyridine with 2,6-dichloro-4nitrophenol’ I. Majerz, W. Sawka-Dobrowolska, Institute of Chemistry,
L. Sobczyk*
University of Wroclaw, 50-383 Wroctaw, Joliot-Curie
14, Poland
(Received 10 November 1992) Abstract The structure of the adduct of 3-methylpyridiie with 2,6-dichloro-4-nitrophenol has been determined by X-ray diffraction. The crystals are monoclinic, space group P21/c with a = 7.935(2), b = 23.789(7), c = 7.521(2)& p = 112.44(2)’ and Z = 4. The structure solved by direct methods was refined to R = 0.040 for 1564 non-zero independent reflections. The complex is characterized by one of the shortest N-H.. .O hydrogen bridges with the N. . .O distance equal to 2.544(4$ Both the estimated localization of the proton and the C-O bond length (1.285(4)& indicate that the proton is transferred from oxygen to nitrogen. In contrast, the UV and IR spectra imply a double minimum potential for the proton motion.
Introdul!tlon
The O-H . . . N hydrogen bonded complexes from the so-called “critical” region of ApK, (PK(NH+) - PK(OH)) are of particular interest. The conception of the critical region was formulated by Johnson and Rumon [l] who carried out systematic studies on the solid adducts of benzoic acids with nitrogen bases. In the critical region the IR spectra are characterized by broad bands of protonic stretching vibrations located in the fingerprint region and the lack of absorption above 18OOcm-‘. The complexes of phenols with nitrogen bases behave similarly [2]. Systematic X-ray diffraction studies on the adducts of pcntachlorophenol show [3], in addition, that hydrogen bridges in the critical region are the shortest, reaching particularly small lengths (2.51-2.58 A). Nuclear +Correspondingauthor. ’ Dedicated to Professor C. Sandorfy.
quadrupole resonance (NQR) studies showed that the critical region is characterized by a stepwise change of pNQR (average value of resonance frequencies of chlorine atoms). This means that a stepwise transition from the state without proton transfer (HB) to the proton transfer state (PT) takes place. The problem of the potential for the proton motion in the critical region is still open. In solution there exists without doubt an equilibrium between the HB and PT states. In the solid state, however, either an asymmetric single minimum potential curve or a double minimum potential curve with a low barrier can be postulated. The gathering of information on such types of hydrogen bonded adduct seems to be justified, so it was decided to undertake the study of adducts of 2,6dichloro-4-nitrophenol with pyridines. Information already exists on the NQR spectra of these systems. One of the adducts located in the critical region is that composed of 3-methylpyridine [4]. It was decided to investigate the structure of this
178
adduct by X-ray diffraction. In addition the IR and UV spectra were recorded. Experimental The complex was obtained from equimolar amounts of 3-methylpyridine and 2,6-dichloro-4nitrophenol in a&on&rile solution. The yellow crystals were grown from Ccl4 by slow isothermal solvent evaporation. Preliminary Weissenberg photographs showed the space group to be Q/c (monoclinic system). A specimen 0.6 x 0.5 x 0.5mm was cut from a large crystal and sealed in a capillary. All measurements were performed on a Kuma diffraction KM4 computer controlled k-axis diffractometer with graphite monochromatization. Cell parameters were obtained from a least-squares fit of the setting angles of 25 reflections in the range 20 < 28 < 35”. A summary of crystal and intensity collection data is given in Table 1. The diffraction data were collected at 292 f 1 K with MoKa radiation and w/28 scan technique up to 28 = 50”. The intensities of three standard reflections,
I. Majerz et al./J. Mol. Strut., 297 (1993) 177-184
monitored after each 100 intensity scans, showed a variation off 2%. A total of 3033 reflections were collected, of which 1564 2 2.5a(I) were used for the structure determination. The crystal structure was solved by direct methods using SHELX 86 [5] and refined by a blockdiagonal least-squares technique. All H atom positions were found from a difference synthesis. An absorption correction following the DIFABS procedure [6] was applied: minimum and maximum absorption corrections were 0.665 and 1.498 respectively. Most calculations were performed with locally modified XTL/XTLE programs [7]. Neutral atomic scattering factors for all atoms were taken from ref. 8. The function minimized was C w(]&;ol- ]FJ)2 where w = l/a2(Fo). The final R and R, values were 0.040 and 0.03 for the observed reflections. For the last cycle of the refinement the maximum A/a ratio was 0.01 and the final difference map showed a general background within f 0.16 e Ae3. The IR spectrum was recorded for pellets in KBr on a Bruker FT-IR IFS 113~ spectrophotometer. For the UV measurement a large single crystal of
Table 1
Summary of crystal data, data collection, and refinement conditions Compound Molecular weight a(A) b(A) c(A) py($y Z
0: (Mgme3) & (Mgmm3) Space group Temperature (K) Radiation A(A) Linear absorption coefficient, &ru-‘) Number of unique reflections used in refinement Z > 2.50(Z) Final R Final R, S FWO) *Measured by flotation in CC&/ethyl bromide.
C&lzHzN020301.13 7.935(2) 23.789(7) 7.521(2) 112.44(2) 1312.2(6) 4 1.52(l) 1524(l)
.C6H7N+
G/c 292( 1) MoKa from graphite monochromatization 0.71069 5.02 1564 0.040 0.030 1.9 616
179
I. Majerz et al./J. Mol. Strut., 297 (1993) 177-184 Table 2 Final atomic parameters Atom 01 02 03 Nl N2 Cl2 Cl6 Cl c2 c3 c4 c5 C6 Cl1 c21 c31 C41 c51 C61
X
Y
Z
B#)
0.5469(3)
0.6371(l) 0.8789(l) 0.8978( 1) 0.5425(l) 0.8639(l) 0.70930(4) 0.66204(4) 0.6895(l) 0.7311(l) 0.7877(l) 0.8047( 1) 0.7667(l) 0.7101(l) 0.5229(l) 0.4685(l) 0.4338(l) 0.4544( 1) 0.5092(l) O&82(2)
0.3794(4) 0.6452(4) 0.4379(4) 0.4850(4) 0.5275(4) 0.15274(15) 0.68371(16) 0.4175(5) 0.3196(5) 0.3534(5) 0.4900(5) 0.5919(5) 0.5558(S) 0.6586(5) 0.7112(5) 0.5773(5) 0.3987(5) 0.3536(5) 0.9082(6)
4.2( 1) 6.0( 1) 5.3(l) 3.8(l) 4.0( 1) 4.43(4) 4.93(4) 2.9(l) 3.0(l) 3.2(l) 3.0(l) 3.2(l) 3.1(l) 3.7(l)
0.8325(3) 0.5650(3) 0.7026(4) 0.6850(4) 0.24558(11) 0.91381(12) 0.5825(4) 0.4532(4) 0.4849(4) 0.6505(4) 0.7825(4) 0.7488(4) 0.7264(4) 0.7747(4) 0.7995(4) 0.7748(5) 0.7265(4) 0.7964(5)
3.40) 3.5(l) 4.0( 1) 4.1(2) 5.3(2)
a&, = (l/3) xi cj BijaiaTa;aj.
3-methylpyridine-pentachlorophenol adduct was grown. The sample of this crystal was glued with paraffin onto a quartz plate and polished up to a thin layer by using silk. During recording of the spectrum on a Cary 13 UV/VIS spectrometer the base line was reduced and the signal averaging time was equal to lOs, the data interval being 0.7nm and spectral bandwidth 2nm. Preparation of
thinner monocrystalline owing to decomposition surface.
plates was not possible of the compound on the
Results and discussion The final atomic coordinates and thermal parameters of 3-methylpyridine-2,6-dichloro-4-
Table 3 Final H-atom parameters Atom
X
Y
Z
4s-z (A2)
Hl H3 H5 Hll H31 H41 H51 H61 H62 H63
0.664(4) 0.401(3) 0.897(3) 0.706(4) 0.823(4) 0.789(4) 0.700(4) 0.907(4) 0.837(4) 0.696(5)
0.581(l) 0.814(l) 0.778( 1) 0.548(l) 0.391(2) 0*431(l) 0.528(l) 0.430( 1) 0.476( 1) 0.434(2)
0.453(5) 0.283(4) 0.685(4) 0.743(5) 0.600(4) 0.304(5) 0.222(5) 0.968(5) 1.008(5) 0.916(6)
8.6(10) 3.7(7) 3.9(7) 5.1(S) 4.6(S) 6.0(9) 5.5(S) 9.0(11) 8.8(11) 11.5(12)
180
I. Majerz et al./J. Mol. Strut.. 297 (1993) 177-184
Table 4 Anisotropic
thermal parameters
of 3-methylpyridine-2,6-dichloro-4-nitrophenol
with e.s.d. values in parentheses
Atom
Bll
B22
B33
B12
B13
B23
01 02 03 Nl N2 Cl2 Cl6 Cl c2 c3 c4 c5 C6 Cl1 c21 c31 c41 c51 C61
4.52(11) 5.63(13) 7.26(15) 4.66(13) 5.16(14)
3.00(10) 4.60( 14) 3.38( 11) 3.15(13) 3.55(13) 5.08(S) 4.38(4) 3.15(14) 3.87(16) 3.28( 14) 2.90(14) 4.02(16) 3.68(16) 3.72(16) 4.15(17) 2.98(15) 3.34(16) 4.41(19) 6.21(25)
4.98(14) 7.62(19) 5.64(16) 4.01(16) 4.23( 17) 4.57(5) 5.04(6) 2.87(16) 2.57(17) 3.07( 17) 3.11(17) 3.04(17) 2.80( 16) 3.64( 19) 2.54(17) 3.36(18) 3.84(19) 3.22(19) 3.12(20)
-0.05(8) -l.Ol(ll) O&(11) 0.17(10) -0.25( 11) -0.18(3) 0.86(3) 0.02( 10) O.OO(10) 0.59(12) -0.20( 11) -0.38(11) 0.27( 11) -0.25( 12) -0.54( 12) 0.27(12) 0.43(13) 0.08( 14) -0.89( 18)
1.72(11) 2.30(13) 2.80(13) 2.05(12) 2.76(13) 1.30(3) 0.89(4) 2.03(12) 1.70(12) 2.08(13) 2.28( 13) 1.90(12) 1.86(12) 2.34( 14) 1.71(12) 1.82(14) 2.85(16) 2.30(15) 2.39(17)
-0.24( 10) -2.18(14) 0.65( 12) 0.55( 12) -0.42( 13) -0.47(4) 0.24(4) 0.03( 12) -0.14(13) 0.46( 14) -0.19(12) -0.34( 13) 0.15(13) -0.60( 14) -0.10(13) 0.02( 13) -0.23(15) 0.10(16) 0.19(19)
3.44(3) 4.53(4) 3.40(12) 3.06(12) 3X7(13) 3.94( 14) 3.29(12) 3.47(13) 4.54(15) 3.99(14) 4.45(15) 5.66(18) 5.20( 17) 6.95(21)
The temperature
factor is of the form: T= exp[f(Bllh2d’
nitrophenol with their standard deviations are listed in Tables 2-4. Table 5 shows principal interatomic distances and angles of 3-methylpyridine2,6-dichloro-4-nitrophenolate, and the molecular structure, atom numbering and stereoview of packing are shown in Figs. 1 and 2. The molecule contains pyridine and phenol moieties linked by a hydrogen bond of length 2.544(4)& which is one of the shortest values reported so far. This NH0 hydrogen bond length
+ B&b**
+ B33f2c2*+ 2B12hka*b* + 2B13hZa*c*+ B2&lb*c*)]
is similar to the N. . .O length in the 4-methylpyridine-pentachlorophenol adduct (2.552(4)& [9]. Differences between both complexes are in the OH and HN distances. For 4-methylpyridine-pentachlorophenolate they are 1.09(6) and 1.47(6) A respectively, while for 3-methylpyridine-2,6dichloro-4-nitrophenolate they are 1M(3) and 0.97(3)A respectively. In spite of a very short 0. . . N distance in the 3-methylpyridine-2,6dichloro-4nitrophenolate complex, a proton is
H62
02 Fig. 1. Molecular structure and atom numbering
of the adduct of 3-methylpyridine
with 2,6-dichloro-4-nitrophenol.
181
I. Majerz et al./J. Mol. Struct.. 297 (1993) 177-184
Table 5 Bond lengths (A) and bond angles (deg) with e.s.d. values in parenthesesfor the complex of 3-methylpyridinewith 2,6-dichloroCnitrophenol Bond lengths N(l)...O(l) O(1). . . H(1) C(l)-C(2) C(2)-C(3) C(4)-C(5) N( I)-C(l 1) C(1 l)-C(21) C(31)-C(41) C(21)-C(61) C(6)-Cl(6) N(2)-O(2) C-H Bond angles N(l)-H(l)...O(l) O(l)-C(l)-C(2) C(2)-C( 1)-C(6) C(2)-C(3)-C(4) C(4)-C(5)-C(6) C(ll)-N(l)-C(51) N(l)-C(Sl)-C(41) C(21)-C(31)-C(41) C(31)-C(21)-C(61) C(3)-C(4)-N(2) C(4)-N(2)-O(3) O(2)-N(2)-O(3)
2.544(4) 1M(3) 1.414(4) 1.375(4) 1.375(5) 1.330(5) 1.363(5) 1.372(5) 1.505(5) 1.727(3) 1.221(4) 0.89(4)-1.05(3) 165(3) 120.6(3) 115.2(3) 118.6(3) 118.9(3) 120.8(3) 119.2(3) 119.7(3) 122.2(3) 119.1(3) 118.9(3) 122.2(3)
evidently located at the pyridine N atom. The C(l)0( 1) length, equal to 1.285(4) & is close to that for the phenolate anion (1.36A for phenol and 1.27 A for phenolate) [lo]. In the adduct of 3-methylpyridine with 2,6-
Fig. 2. Stereoscopic view of the packing of the adduct of 3-methylpyridine with 2,6-dichloro-4-nitrophenol.
0.97(3) 1.285(4) 1.420(5) 1.384(5) 1.380(5) 1.335(5) 1.375(5) 1.372(5) 1.726(3) l&2(4) 1.233(4)
H(l)-N(1) 0(1)-C(l) C(l)-C(6) C(3)-C(4) C(5)-C(6) N(l)-C(51) C(21)-C(31) C(41)-C(51) C(2)-Cl(2) C(4)-N(2) N(2)-O(3)
I C(l)-O(l)...H(l) 0( I)-C( 1)-C(6) C( l)-C(2)-C(3) C(3)-C(4)-C(5) C(S)-C(6)-C( 1) N(l)-C(ll)-C(21) C(l l)-C(21)-C(31) C(31)-C(41)-C(51) C(l l)-C(21)-C(61) C(5)-C(4)-N(2) C(4)-N(2)-O(2)
133(l) 124.2(3) 123.0(3) 121.8(3) 122.5(3) 122.5(3) 117.4(3) 120.4(3) 120.3(3) 119.1(3) 119.0(3)
dichloro-4-nitrophenol, apart from hydrogen bonding, Van der Waals contact between the H( 1) - . . Cl(6) atoms is present. The H( 1) - . . Cl(6) distance is smaller than the Van der Waals radii sum and equals 2.83(3) A but the bifurcated hydrogen bond is not present [l 11. The planes between pyridine and phenol rings are near to perpendicular. Table 6 shows that the angles between the normals to pyridine and phenol ring planes are 65.3(5)“. The distances of the H(1) atom to phenol and the pyridine planes are 0.1 O(4) and 0.03(4) A, respectively. The nitro group is coplanar with the phenyl ring. The N(2)-C(4) bond length, equal to l&2(4) A, indicates some double bond character [12]. The IR spectrum of 3-methylpyridine-2,6dichloro-4-nitrophenolate (Fig.3) is typical of the shortest OHN hydrogen bonds. It is characterized by the disap pearance of the absorption above 18OOcm-’ and
182
I. Majerz et al./J. Mol. Struct., 297 (1993) 177-184
.----_
183
I. Majerz et al./J. Mol. Struck, 297 (1993) 177-184
Table 6 Atom-to-plane distance (A) and aqles between the normals to the planes (deg) Plane A C(l)
C(2)
0.003(3) C(6) -0.001(3) O(3) -0.021(3)
-0.002(3) CJ(2) -o.035(1)a O(l) 0.012(2)”
C(3) O.OOO(3) Cl(6) -0.009( l)a H(l) O.lO(4)”
C(4) 0.002(3) N(2) -0.002(3)’ N(l) 0.056(3)”
C(5) -0.002(3) O(2) 0.026(3)”
N(1)
CU 1)
CGW
O.OOl(3) CC511 -0.002(4)
-0.001(4) C(61) -0.024(4)”
O.OOl(3) O(l) -0.508(2)a
C(31) -0.001(4) J-W) 0.03(4)”
C(41) -0.001(4) C(l) -0.060(3)=
00)
O(3) O.OOO(3)
Plane B
Plane C N(2)
O.OOO(3) A-B B-C
-0.000(3) 65.3(5) 1.4(6)
a Atoms not included in the planes.
the presence
of a broad absorption of complex shape in the fingerprint region. This means that despite the localization of the proton at the nitrogen atom the potential for the proton motion possesses a particular shape. There is no direct correlation between the crystallographic geometry of
the OHN hydrogen bonding and the IR spectroscopic behaviour.
250
350
450 A,nm
Fig. 4. UV spectrum of the adduct of 3-methylpyridine with 2,6-dichloro+nitrophenol: (a) Urn precipitated from methanol and (b) single crystal thin layer.
Even more strange, from this point of view, is the UV spectrum of the adduct. The W spectrum of a single crystal of the 3-methylpyridine-2,6dichloro-4nitrophenol adduct is shown in Fig. 4. The W spectrum consists of two bands at 390 and 320 nm, which correspond to the HB and PT states of phenol. The position of the 2,6-dichloro-4-nitrophenolate anion in water is located at about 400 nm while that of non-ionized phenol is at 294 mn [13]. The W spectrum for the monocrystalline plate is very similar to that recorded for the polycrystalline layer precipitated from the solution in methanol. In conclusion it can be said that the most important crystallographic parameter of the OHN hydrogen bond is its length. When the 0.. . N distance reaches some small value, anomalies in the IR spectrum appear. Also, in the W spectra, two bands corresponding to the HB and PT states are observed. Localization of the proton based on X-ray diffraction should be treated with great caution. References 1 S.L. Johnson and K.A. Rumon, J. Phys. Chem., 14 (1965) 74.
184 2 Z. Malarski, M. Rospenk, L. Sobczyk and E. Grech, J. Phys. Chem., 86 (1982) 401. 3 I. Majerz, Z. Malarski and W. Sawka-Dobrowolska, J. Mol. Struct., 249 (1991) 109 and references cited therein. 4 E. Grech, J. Kalenik and L. Sobczyk, J. Chem. Sot., Faraday Trans. 1,75 (1979) 1587. 5 G.M. Sheldrick, SHELX 86,Program for the solution of crystal structure, University of Gottingen, 1986. 6 N. Walker and D. Stuart, Acta Crystallogr., Sect. A, 39 (1983) 158. 7 Syntex ~TL~TLE Structure Determination System, Syntex Analytical Instruments, Cupertino, CA, 1976. 8 International Tables for X-ray Crystallography, Vol. IV, Kynoch Press, Birmingham, 1974. 9 Z. Malarski, I. Majerz and T. Lis, J. Mol. Struct., 158
I. Majerz et al./J. Mol. Struct., 297 (1993) 177-184 (1987) 369. 10 T. Pedersen, N.W. Larsen and L. Nygard, J. Mol. Struct., 4 (1969) 59. M. Perrin and P. Michel, Acta Crystallogr., Sect. B, 31 (1973) 253. E.K. Andersen and J.G.K. Andersen, Acta Crystallogr., Sect. B, 32 (1975) 387. K. Maartmann-Moe, Acta Crystallogr., Sect. B, 25 (1969) 1452. I. Van Bellingen, G. Germain, P. Piret and M. Van Meersche, Acta Crystallogr., Sect. B, 27 (1971) 553,560. 11 M. Jaskblski, Pol. J. Chem., 58 (1984) 955. 12 R. Kawai, S. Kashino and M. Ha&a, Acta Crystallogr., Sect. B, 32 (1976) 1972. 13 H. Romanowski and L. Sobczyk, J. Phys. Chem., 79 (1975) 2535.
Journal of Molecular Structure, 291(1993) 177- 184 0022-2860/93/%06.000 1993 - Elsevier Science Publishers B.V. All rights reserved
Structure and spectroscopic behaviour of the solid adduct of 3-methylpyridine with 2,6-dichloro-4nitrophenol’ I. Majerz, W. Sawka-Dobrowolska, Institute of Chemistry,
L. Sobczyk*
University of Wroclaw, 50-383 Wroctaw, Joliot-Curie
14, Poland
(Received 10 November 1992) Abstract The structure of the adduct of 3-methylpyridiie with 2,6-dichloro-4-nitrophenol has been determined by X-ray diffraction. The crystals are monoclinic, space group P21/c with a = 7.935(2), b = 23.789(7), c = 7.521(2)& p = 112.44(2)’ and Z = 4. The structure solved by direct methods was refined to R = 0.040 for 1564 non-zero independent reflections. The complex is characterized by one of the shortest N-H.. .O hydrogen bridges with the N. . .O distance equal to 2.544(4$ Both the estimated localization of the proton and the C-O bond length (1.285(4)& indicate that the proton is transferred from oxygen to nitrogen. In contrast, the UV and IR spectra imply a double minimum potential for the proton motion.
Introdul!tlon
The O-H . . . N hydrogen bonded complexes from the so-called “critical” region of ApK, (PK(NH+) - PK(OH)) are of particular interest. The conception of the critical region was formulated by Johnson and Rumon [l] who carried out systematic studies on the solid adducts of benzoic acids with nitrogen bases. In the critical region the IR spectra are characterized by broad bands of protonic stretching vibrations located in the fingerprint region and the lack of absorption above 18OOcm-‘. The complexes of phenols with nitrogen bases behave similarly [2]. Systematic X-ray diffraction studies on the adducts of pcntachlorophenol show [3], in addition, that hydrogen bridges in the critical region are the shortest, reaching particularly small lengths (2.51-2.58 A). Nuclear +Correspondingauthor. ’ Dedicated to Professor C. Sandorfy.
quadrupole resonance (NQR) studies showed that the critical region is characterized by a stepwise change of pNQR (average value of resonance frequencies of chlorine atoms). This means that a stepwise transition from the state without proton transfer (HB) to the proton transfer state (PT) takes place. The problem of the potential for the proton motion in the critical region is still open. In solution there exists without doubt an equilibrium between the HB and PT states. In the solid state, however, either an asymmetric single minimum potential curve or a double minimum potential curve with a low barrier can be postulated. The gathering of information on such types of hydrogen bonded adduct seems to be justified, so it was decided to undertake the study of adducts of 2,6dichloro-4-nitrophenol with pyridines. Information already exists on the NQR spectra of these systems. One of the adducts located in the critical region is that composed of 3-methylpyridine [4]. It was decided to investigate the structure of this
178
adduct by X-ray diffraction. In addition the IR and UV spectra were recorded. Experimental The complex was obtained from equimolar amounts of 3-methylpyridine and 2,6-dichloro-4nitrophenol in a&on&rile solution. The yellow crystals were grown from Ccl4 by slow isothermal solvent evaporation. Preliminary Weissenberg photographs showed the space group to be Q/c (monoclinic system). A specimen 0.6 x 0.5 x 0.5mm was cut from a large crystal and sealed in a capillary. All measurements were performed on a Kuma diffraction KM4 computer controlled k-axis diffractometer with graphite monochromatization. Cell parameters were obtained from a least-squares fit of the setting angles of 25 reflections in the range 20 < 28 < 35”. A summary of crystal and intensity collection data is given in Table 1. The diffraction data were collected at 292 f 1 K with MoKa radiation and w/28 scan technique up to 28 = 50”. The intensities of three standard reflections,
I. Majerz et al./J. Mol. Strut., 297 (1993) 177-184
monitored after each 100 intensity scans, showed a variation off 2%. A total of 3033 reflections were collected, of which 1564 2 2.5a(I) were used for the structure determination. The crystal structure was solved by direct methods using SHELX 86 [5] and refined by a blockdiagonal least-squares technique. All H atom positions were found from a difference synthesis. An absorption correction following the DIFABS procedure [6] was applied: minimum and maximum absorption corrections were 0.665 and 1.498 respectively. Most calculations were performed with locally modified XTL/XTLE programs [7]. Neutral atomic scattering factors for all atoms were taken from ref. 8. The function minimized was C w(]&;ol- ]FJ)2 where w = l/a2(Fo). The final R and R, values were 0.040 and 0.03 for the observed reflections. For the last cycle of the refinement the maximum A/a ratio was 0.01 and the final difference map showed a general background within f 0.16 e Ae3. The IR spectrum was recorded for pellets in KBr on a Bruker FT-IR IFS 113~ spectrophotometer. For the UV measurement a large single crystal of
Table 1
Summary of crystal data, data collection, and refinement conditions Compound Molecular weight a(A) b(A) c(A) py($y Z
0: (Mgme3) & (Mgmm3) Space group Temperature (K) Radiation A(A) Linear absorption coefficient, &ru-‘) Number of unique reflections used in refinement Z > 2.50(Z) Final R Final R, S FWO) *Measured by flotation in CC&/ethyl bromide.
C&lzHzN020301.13 7.935(2) 23.789(7) 7.521(2) 112.44(2) 1312.2(6) 4 1.52(l) 1524(l)
.C6H7N+
G/c 292( 1) MoKa from graphite monochromatization 0.71069 5.02 1564 0.040 0.030 1.9 616
179
I. Majerz et al./J. Mol. Strut., 297 (1993) 177-184 Table 2 Final atomic parameters Atom 01 02 03 Nl N2 Cl2 Cl6 Cl c2 c3 c4 c5 C6 Cl1 c21 c31 C41 c51 C61
X
Y
Z
B#)
0.5469(3)
0.6371(l) 0.8789(l) 0.8978( 1) 0.5425(l) 0.8639(l) 0.70930(4) 0.66204(4) 0.6895(l) 0.7311(l) 0.7877(l) 0.8047( 1) 0.7667(l) 0.7101(l) 0.5229(l) 0.4685(l) 0.4338(l) 0.4544( 1) 0.5092(l) O&82(2)
0.3794(4) 0.6452(4) 0.4379(4) 0.4850(4) 0.5275(4) 0.15274(15) 0.68371(16) 0.4175(5) 0.3196(5) 0.3534(5) 0.4900(5) 0.5919(5) 0.5558(S) 0.6586(5) 0.7112(5) 0.5773(5) 0.3987(5) 0.3536(5) 0.9082(6)
4.2( 1) 6.0( 1) 5.3(l) 3.8(l) 4.0( 1) 4.43(4) 4.93(4) 2.9(l) 3.0(l) 3.2(l) 3.0(l) 3.2(l) 3.1(l) 3.7(l)
0.8325(3) 0.5650(3) 0.7026(4) 0.6850(4) 0.24558(11) 0.91381(12) 0.5825(4) 0.4532(4) 0.4849(4) 0.6505(4) 0.7825(4) 0.7488(4) 0.7264(4) 0.7747(4) 0.7995(4) 0.7748(5) 0.7265(4) 0.7964(5)
3.40) 3.5(l) 4.0( 1) 4.1(2) 5.3(2)
a&, = (l/3) xi cj BijaiaTa;aj.
3-methylpyridine-pentachlorophenol adduct was grown. The sample of this crystal was glued with paraffin onto a quartz plate and polished up to a thin layer by using silk. During recording of the spectrum on a Cary 13 UV/VIS spectrometer the base line was reduced and the signal averaging time was equal to lOs, the data interval being 0.7nm and spectral bandwidth 2nm. Preparation of
thinner monocrystalline owing to decomposition surface.
plates was not possible of the compound on the
Results and discussion The final atomic coordinates and thermal parameters of 3-methylpyridine-2,6-dichloro-4-
Table 3 Final H-atom parameters Atom
X
Y
Z
4s-z (A2)
Hl H3 H5 Hll H31 H41 H51 H61 H62 H63
0.664(4) 0.401(3) 0.897(3) 0.706(4) 0.823(4) 0.789(4) 0.700(4) 0.907(4) 0.837(4) 0.696(5)
0.581(l) 0.814(l) 0.778( 1) 0.548(l) 0.391(2) 0*431(l) 0.528(l) 0.430( 1) 0.476( 1) 0.434(2)
0.453(5) 0.283(4) 0.685(4) 0.743(5) 0.600(4) 0.304(5) 0.222(5) 0.968(5) 1.008(5) 0.916(6)
8.6(10) 3.7(7) 3.9(7) 5.1(S) 4.6(S) 6.0(9) 5.5(S) 9.0(11) 8.8(11) 11.5(12)
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Table 4 Anisotropic
thermal parameters
of 3-methylpyridine-2,6-dichloro-4-nitrophenol
with e.s.d. values in parentheses
Atom
Bll
B22
B33
B12
B13
B23
01 02 03 Nl N2 Cl2 Cl6 Cl c2 c3 c4 c5 C6 Cl1 c21 c31 c41 c51 C61
4.52(11) 5.63(13) 7.26(15) 4.66(13) 5.16(14)
3.00(10) 4.60( 14) 3.38( 11) 3.15(13) 3.55(13) 5.08(S) 4.38(4) 3.15(14) 3.87(16) 3.28( 14) 2.90(14) 4.02(16) 3.68(16) 3.72(16) 4.15(17) 2.98(15) 3.34(16) 4.41(19) 6.21(25)
4.98(14) 7.62(19) 5.64(16) 4.01(16) 4.23( 17) 4.57(5) 5.04(6) 2.87(16) 2.57(17) 3.07( 17) 3.11(17) 3.04(17) 2.80( 16) 3.64( 19) 2.54(17) 3.36(18) 3.84(19) 3.22(19) 3.12(20)
-0.05(8) -l.Ol(ll) O&(11) 0.17(10) -0.25( 11) -0.18(3) 0.86(3) 0.02( 10) O.OO(10) 0.59(12) -0.20( 11) -0.38(11) 0.27( 11) -0.25( 12) -0.54( 12) 0.27(12) 0.43(13) 0.08( 14) -0.89( 18)
1.72(11) 2.30(13) 2.80(13) 2.05(12) 2.76(13) 1.30(3) 0.89(4) 2.03(12) 1.70(12) 2.08(13) 2.28( 13) 1.90(12) 1.86(12) 2.34( 14) 1.71(12) 1.82(14) 2.85(16) 2.30(15) 2.39(17)
-0.24( 10) -2.18(14) 0.65( 12) 0.55( 12) -0.42( 13) -0.47(4) 0.24(4) 0.03( 12) -0.14(13) 0.46( 14) -0.19(12) -0.34( 13) 0.15(13) -0.60( 14) -0.10(13) 0.02( 13) -0.23(15) 0.10(16) 0.19(19)
3.44(3) 4.53(4) 3.40(12) 3.06(12) 3X7(13) 3.94( 14) 3.29(12) 3.47(13) 4.54(15) 3.99(14) 4.45(15) 5.66(18) 5.20( 17) 6.95(21)
The temperature
factor is of the form: T= exp[f(Bllh2d’
nitrophenol with their standard deviations are listed in Tables 2-4. Table 5 shows principal interatomic distances and angles of 3-methylpyridine2,6-dichloro-4-nitrophenolate, and the molecular structure, atom numbering and stereoview of packing are shown in Figs. 1 and 2. The molecule contains pyridine and phenol moieties linked by a hydrogen bond of length 2.544(4)& which is one of the shortest values reported so far. This NH0 hydrogen bond length
+ B&b**
+ B33f2c2*+ 2B12hka*b* + 2B13hZa*c*+ B2&lb*c*)]
is similar to the N. . .O length in the 4-methylpyridine-pentachlorophenol adduct (2.552(4)& [9]. Differences between both complexes are in the OH and HN distances. For 4-methylpyridine-pentachlorophenolate they are 1.09(6) and 1.47(6) A respectively, while for 3-methylpyridine-2,6dichloro-4-nitrophenolate they are 1M(3) and 0.97(3)A respectively. In spite of a very short 0. . . N distance in the 3-methylpyridine-2,6dichloro-4nitrophenolate complex, a proton is
H62
02 Fig. 1. Molecular structure and atom numbering
of the adduct of 3-methylpyridine
with 2,6-dichloro-4-nitrophenol.
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Table 5 Bond lengths (A) and bond angles (deg) with e.s.d. values in parenthesesfor the complex of 3-methylpyridinewith 2,6-dichloroCnitrophenol Bond lengths N(l)...O(l) O(1). . . H(1) C(l)-C(2) C(2)-C(3) C(4)-C(5) N( I)-C(l 1) C(1 l)-C(21) C(31)-C(41) C(21)-C(61) C(6)-Cl(6) N(2)-O(2) C-H Bond angles N(l)-H(l)...O(l) O(l)-C(l)-C(2) C(2)-C( 1)-C(6) C(2)-C(3)-C(4) C(4)-C(5)-C(6) C(ll)-N(l)-C(51) N(l)-C(Sl)-C(41) C(21)-C(31)-C(41) C(31)-C(21)-C(61) C(3)-C(4)-N(2) C(4)-N(2)-O(3) O(2)-N(2)-O(3)
2.544(4) 1M(3) 1.414(4) 1.375(4) 1.375(5) 1.330(5) 1.363(5) 1.372(5) 1.505(5) 1.727(3) 1.221(4) 0.89(4)-1.05(3) 165(3) 120.6(3) 115.2(3) 118.6(3) 118.9(3) 120.8(3) 119.2(3) 119.7(3) 122.2(3) 119.1(3) 118.9(3) 122.2(3)
evidently located at the pyridine N atom. The C(l)0( 1) length, equal to 1.285(4) & is close to that for the phenolate anion (1.36A for phenol and 1.27 A for phenolate) [lo]. In the adduct of 3-methylpyridine with 2,6-
Fig. 2. Stereoscopic view of the packing of the adduct of 3-methylpyridine with 2,6-dichloro-4-nitrophenol.
0.97(3) 1.285(4) 1.420(5) 1.384(5) 1.380(5) 1.335(5) 1.375(5) 1.372(5) 1.726(3) l&2(4) 1.233(4)
H(l)-N(1) 0(1)-C(l) C(l)-C(6) C(3)-C(4) C(5)-C(6) N(l)-C(51) C(21)-C(31) C(41)-C(51) C(2)-Cl(2) C(4)-N(2) N(2)-O(3)
I C(l)-O(l)...H(l) 0( I)-C( 1)-C(6) C( l)-C(2)-C(3) C(3)-C(4)-C(5) C(S)-C(6)-C( 1) N(l)-C(ll)-C(21) C(l l)-C(21)-C(31) C(31)-C(41)-C(51) C(l l)-C(21)-C(61) C(5)-C(4)-N(2) C(4)-N(2)-O(2)
133(l) 124.2(3) 123.0(3) 121.8(3) 122.5(3) 122.5(3) 117.4(3) 120.4(3) 120.3(3) 119.1(3) 119.0(3)
dichloro-4-nitrophenol, apart from hydrogen bonding, Van der Waals contact between the H( 1) - . . Cl(6) atoms is present. The H( 1) - . . Cl(6) distance is smaller than the Van der Waals radii sum and equals 2.83(3) A but the bifurcated hydrogen bond is not present [l 11. The planes between pyridine and phenol rings are near to perpendicular. Table 6 shows that the angles between the normals to pyridine and phenol ring planes are 65.3(5)“. The distances of the H(1) atom to phenol and the pyridine planes are 0.1 O(4) and 0.03(4) A, respectively. The nitro group is coplanar with the phenyl ring. The N(2)-C(4) bond length, equal to l&2(4) A, indicates some double bond character [12]. The IR spectrum of 3-methylpyridine-2,6dichloro-4-nitrophenolate (Fig.3) is typical of the shortest OHN hydrogen bonds. It is characterized by the disap pearance of the absorption above 18OOcm-’ and
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I. Majerz et al./J. Mol. Struct., 297 (1993) 177-184
.----_
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I. Majerz et al./J. Mol. Struck, 297 (1993) 177-184
Table 6 Atom-to-plane distance (A) and aqles between the normals to the planes (deg) Plane A C(l)
C(2)
0.003(3) C(6) -0.001(3) O(3) -0.021(3)
-0.002(3) CJ(2) -o.035(1)a O(l) 0.012(2)”
C(3) O.OOO(3) Cl(6) -0.009( l)a H(l) O.lO(4)”
C(4) 0.002(3) N(2) -0.002(3)’ N(l) 0.056(3)”
C(5) -0.002(3) O(2) 0.026(3)”
N(1)
CU 1)
CGW
O.OOl(3) CC511 -0.002(4)
-0.001(4) C(61) -0.024(4)”
O.OOl(3) O(l) -0.508(2)a
C(31) -0.001(4) J-W) 0.03(4)”
C(41) -0.001(4) C(l) -0.060(3)=
00)
O(3) O.OOO(3)
Plane B
Plane C N(2)
O.OOO(3) A-B B-C
-0.000(3) 65.3(5) 1.4(6)
a Atoms not included in the planes.
the presence
of a broad absorption of complex shape in the fingerprint region. This means that despite the localization of the proton at the nitrogen atom the potential for the proton motion possesses a particular shape. There is no direct correlation between the crystallographic geometry of
the OHN hydrogen bonding and the IR spectroscopic behaviour.
250
350
450 A,nm
Fig. 4. UV spectrum of the adduct of 3-methylpyridine with 2,6-dichloro+nitrophenol: (a) Urn precipitated from methanol and (b) single crystal thin layer.
Even more strange, from this point of view, is the UV spectrum of the adduct. The W spectrum of a single crystal of the 3-methylpyridine-2,6dichloro-4nitrophenol adduct is shown in Fig. 4. The W spectrum consists of two bands at 390 and 320 nm, which correspond to the HB and PT states of phenol. The position of the 2,6-dichloro-4-nitrophenolate anion in water is located at about 400 nm while that of non-ionized phenol is at 294 mn [13]. The W spectrum for the monocrystalline plate is very similar to that recorded for the polycrystalline layer precipitated from the solution in methanol. In conclusion it can be said that the most important crystallographic parameter of the OHN hydrogen bond is its length. When the 0.. . N distance reaches some small value, anomalies in the IR spectrum appear. Also, in the W spectra, two bands corresponding to the HB and PT states are observed. Localization of the proton based on X-ray diffraction should be treated with great caution. References 1 S.L. Johnson and K.A. Rumon, J. Phys. Chem., 14 (1965) 74.
184 2 Z. Malarski, M. Rospenk, L. Sobczyk and E. Grech, J. Phys. Chem., 86 (1982) 401. 3 I. Majerz, Z. Malarski and W. Sawka-Dobrowolska, J. Mol. Struct., 249 (1991) 109 and references cited therein. 4 E. Grech, J. Kalenik and L. Sobczyk, J. Chem. Sot., Faraday Trans. 1,75 (1979) 1587. 5 G.M. Sheldrick, SHELX 86,Program for the solution of crystal structure, University of Gottingen, 1986. 6 N. Walker and D. Stuart, Acta Crystallogr., Sect. A, 39 (1983) 158. 7 Syntex ~TL~TLE Structure Determination System, Syntex Analytical Instruments, Cupertino, CA, 1976. 8 International Tables for X-ray Crystallography, Vol. IV, Kynoch Press, Birmingham, 1974. 9 Z. Malarski, I. Majerz and T. Lis, J. Mol. Struct., 158
I. Majerz et al./J. Mol. Struct., 297 (1993) 177-184 (1987) 369. 10 T. Pedersen, N.W. Larsen and L. Nygard, J. Mol. Struct., 4 (1969) 59. M. Perrin and P. Michel, Acta Crystallogr., Sect. B, 31 (1973) 253. E.K. Andersen and J.G.K. Andersen, Acta Crystallogr., Sect. B, 32 (1975) 387. K. Maartmann-Moe, Acta Crystallogr., Sect. B, 25 (1969) 1452. I. Van Bellingen, G. Germain, P. Piret and M. Van Meersche, Acta Crystallogr., Sect. B, 27 (1971) 553,560. 11 M. Jaskblski, Pol. J. Chem., 58 (1984) 955. 12 R. Kawai, S. Kashino and M. Ha&a, Acta Crystallogr., Sect. B, 32 (1976) 1972. 13 H. Romanowski and L. Sobczyk, J. Phys. Chem., 79 (1975) 2535.