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Crystal structure of 3-diethylaminomethyl-2,2′-biphenol
Journal of Molecular Structure 616 (2002) 33–36 www.elsevier.com/locate/molstruc
Crystal structure of 3-diethylaminomethyl-2,20 -biphenol Seik Weng Nga, Grzegorz Wojciechowskib, Bogumil Brzezinskib,* a
b
Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur, Malaysia Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60780, Poznan, Poland Received 8 March 2002; accepted 2 April 2002
Abstract Crystals of 3-diethylaminomethyl-2,20 -biphenol were examined using X-ray diffraction and FT-IR spectroscopy. Their space b ¼ 92:411ð3Þ8 and Z ¼ 8: The unit cell contains two group is P21 =c with a ¼ 7:305ð1Þ; b ¼ 13:816ð2Þ; c ¼ 29:232ð4Þ A; symmetry-independent zwitterions. The hydrogen atom of the protonated diethylaminomethyl group is linked to the negatively charged phenolate oxygen atom, which in turn is linked to the hydroxyl group by a short hydrogen bond (molecule a: molecule b: N· · ·O ¼ 2:593ð4Þ; O· · ·O ¼ 2:489ð4Þ A). N· · ·O ¼ 2:604ð3Þ; O· · ·O ¼ 2:512ð3Þ A; The OH· · ·O2 · · ·Hþ N bifurcated intramolecular hydrogen bonds are crystallographically asymmetric. The IR spectrum of the crystals confirms very well the results obtained by the X-ray study. Instead of continuous absorption, only broad bands are found indicating relatively low proton polarisability in the two types of intramolecular hydrogen bonds. q 2002 Elsevier Science B.V. All rights reserved. Keywords: 3-diethylaminomethyl-2,20 -biphenol; Intramolecular hydrogen bond; Cooperative hydrogen bond; X-ray; Crystal structure; FT-IR spectroscopy
1. Introduction In our previous papers, we have reported the preparation, X-ray and spectroscopic studies of 5,50 dibromo-3-diethylaminomethyl-2,20 -biphenol and other 5,50 -derivativates of 3-diethylaminomethyl2,20 -biphenol [1 –5]. The FTIR and 1H NMR studies of 5,50 -dibromo-3-diethylaminomethyl-2,20 -biphenol in CH2Cl2 and CH3CN solutions have demonstrated that the protons in the intramolecular hydrogen bonds undergo very fast fluctuation, whereas in the acetonitrile solution this compound was polarised to a greater extent. Because of these fluctuations a * Corresponding author. Tel.: þ48-61-829-1330; fax: þ 48-61865-8008. E-mail address: [email protected] (B. Brzezinski).
continuous absorption in the whole region was observed in the FT-IR spectra. In this paper, X-ray diffraction and FT-IR studies of a crystal of 3-diethylaminomethyl-2,20 -biphenol are reported.
2. Experimental 3-Diethylaminomethyl-2,20 -biphenol was obtained as described [2]. Colourless crystals were obtained by crystallisation from chloroform solution. The FT-IR spectrum of the sample was recorded in KBr pellets at 300 K on an FT-IR spectrometer (Bruker IFS 113v, detector MCT, resolution 2 cm21). The 13,580 room-temperature X-ray intensities for the colourless 0.41 mm £ 0.28 mm £ 0.16 mm
0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 2 8 6 0 ( 0 2 ) 0 0 1 6 5 - 5
34
S.W. Ng et al. / Journal of Molecular Structure 616 (2002) 33–36
Table 1 Atomic coordinates and equivalent isotropic temperature factors (Ueq is defined as one-third the trace of the Uij tensor) Atom
x
y
z
Ueq
O1a O2a N1a C1a C2a C3a C4a C5a C6a C7a C8a C9a C10a C11a C12a C13a C14a C15a C16a C17a O1b O2b N1b C1b C2b C3b C4b C5b C6b C7b C8b C9b C10b C11b C12b C13b C14b (57.3%) C15b (57.3%) C16b (57.3%) C17b (57.3%) C140 (42.7%) C150 (42.7%) C160 (42.7%) C170 (42.7%)
0.0365(3) 0.0051(4) 2 0.0268(4) 0.1716(4) 0.3146(4) 0.4503(5) 0.4482(6) 0.3080(6) 0.1695(5) 0.1763(6) 0.3263(5) 0.4966(6) 0.5131(9) 0.363(1) 0.1947(7) 0.0113(5) 0.1268(5) 0.1606(6) 2 0.2064(5) 2 0.3532(6) 2 0.0140(3) 0.0511(4) 0.0124(4) 2 0.1750(5) 2 0.3014(5) 2 0.4655(5) 2 0.5052(6) 2 0.3814(6) 2 0.2166(6) 2 0.0985(6) 2 0.2689(5) 2 0.4108(5) 2 0.3940(7) 2 0.2315(9) 2 0.0830(7) 2 0.0717(6) 2 0.101(1) 2 0.055(3) 0.2101(8) 0.237(1) 2 0.134(1) 2 0.066(2) 0.153(1) 0.322(2)
0.9755(1) 0.8212(2) 1.1468(2) 1.0138(2) 0.9568(2) 1.0040(3) 1.1025(4) 1.1565(3) 1.1144(2) 0.7890(3) 0.8509(3) 0.8074(4) 0.7076(5) 0.6505(4) 0.6893(3) 1.1705(2) 1.1726(2) 1.2789(3) 1.1821(3) 1.1150(4) 0.2804(2) 0.4281(2) 0.1492(2) 0.3082(2) 0.3609(2) 0.3851(2) 0.3595(3) 0.3068(3) 0.2812(3) 0.4258(2) 0.3908(2) 0.3910(2) 0.4262(3) 0.4626(3) 0.4625(3) 0.2298(3) 0.0612(5) 2 0.001(1) 0.1310(5) 0.1197(6) 0.0739(6) 0.0018(9) 0.0968(7) 0.152(1)
0.0719(1) 0.1163(1) 0.0377(1) 0.0977(1) 0.1162(1) 0.1429(1) 0.1504(1) 0.1321(1) 0.1060(1) 0.1096(1) 0.1086(1) 0.1019(1) 0.0967(2) 0.0992(2) 0.1048(1) 0.0869(1) 0.0080(1) 0.0047(1) 0.0186(1) 0.0256(2) 0.1860(1) 0.1407(1) 0.2494(1) 0.2014(1) 0.1741(1) 0.1931(1) 0.2369(1) 0.2632(1) 0.2462(1) 0.1129(2) 0.1266(1) 0.0939(1) 0.0506(1) 0.0385(2) 0.0688(2) 0.2747(1) 0.2467(4) 0.2069(6) 0.2613(2) 0.3114(2) 0.2368(5) 0.2033(4) 0.2818(4) 0.2776(6)
0.074(1) 0.087(1) 0.069(1) 0.066(1) 0.071(1) 0.096(1) 0.107(1) 0.091(1) 0.071(1) 0.077(1) 0.075(1) 0.109(1) 0.139(2) 0.142(2) 0.104(1) 0.080(1) 0.079(1) 0.117(1) 0.098(1) 0.149(2) 0.098(1) 0.110(1) 0.099(1) 0.077(1) 0.071(1) 0.081(1) 0.102(1) 0.101(1) 0.088(1) 0.086(1) 0.071(1) 0.082(1) 0.101(1) 0.115(2) 0.108(1) 0.119(1) 0.076(3) 0.163(8) 0.089(2) 0.112(3) 0.086(5) 0.061(4) 0.145(5) 0.171(6)
specimen were collected on a Siemens CCD areadetector diffractometer (Mo Ka radiation, The data were averaged for 5715 l ¼ 0:71073 A). reflections, of which 2179 were observable. The
structure was solved by direct methods, and it was refined on F 2 to R ¼ 0:051: The b molecule is disordered in the diethylaminomethyl group, and the two components refined to a 57:43 ratio. The hydrogen atom of protonated diethylaminomethyl group in the molecule a and the hydroxyl hydrogen atoms of both molecules are located and refined; the hydrogen atom of the protonated diethylaminomethyl group in the molecule b was placed in a geometrically sensible position. Crystal data: C17H21NO2, FW ¼ 271:35; monoclinic, P21 =c; a ¼ 7:305ð1Þ; b ¼ 13:816ð2Þ; c ¼ b ¼ 92:411ð3Þ8; V ¼ 2947:8ð7Þ A 3; Z ¼ 29:232ð4Þ A; 23 8; r ¼ 1:223 g cm ; Fð000Þ ¼ 1168; m¼ 0:080 mm21 :
3. Results and discussion 3.1. Description of the structure Fractional atomic coordinates and equivalent isotropic displacement coefficients are listed in Table 1. An ORTEP [6,7] plot of the molecule with the atom numbering scheme is presented in Fig. 1. The geometry of the molecule is given in Table 2. In the unit cell, there are two symmetry-independent zwitterions (a and b). In the molecule a, the two rings are tilted by 40.0(1)8 and in the molecule b, the tilt is 39.1(1)8. The –CH2N(C2H5)2 amino group as a relatively strong base causes the deprotonation of the hydroxyl group at the same ring across a short intramolecular Oð1Þ2 · · ·Nþ ð1Þ hydrogen bond. The hydrogen atom of the protonated diethylaminomethyl group is linked to the negatively charged phenolate oxygen atom, which in turn is linked to the hydroxyl group by a short hydrogen bond [molecule a: N· · ·O ¼ molecule b: N· · ·O ¼ 2:604ð3Þ; O· · ·O ¼ 2:512ð3Þ A; Both OH· · ·O2 · · · 2:593ð4Þ; O· · ·O ¼ 2:489ð4Þ A]. þ H N bifurcated intramolecular hydrogen bonds are crystallographically asymmetric. The Nþ – H· · ·2 O hydrogen bonds are only slightly weaker than the N· · ·H – O one observed in the complex of 2methylpiridine with pentachlorophenol [2.588(3)] [8]. 3.2. FT-IR spectrum The IR spectrum of 3-diethylaminomethyl-2,20 biphenol crystals is shown in Fig. 2. In this spectrum,
S.W. Ng et al. / Journal of Molecular Structure 616 (2002) 33–36
35
Fig. 1. ORTEP plot of one of the two independent molecules at the 50% probability level. Hydrogen atoms are drawn as spheres of arbitrary radii.
in contrast to that of 3-diethylaminomethyl-2,20 biphenol in acetonitrile, there is no continuous absorption in the region of 3000– 400 cm21, but only two bands in the region of 3200 –1600 cm21 with maxima at about 2400 and 1820 cm21, respectively, as well as a broad intense band with a maximum at about 1220 cm21. This hydrogen bonded system does not show very large proton polarisability, so it does not contribute to the so-called Zundel’s polarisability [9 –11]. The broad band with a maximum at about 1220 cm21 can be assigned to the stretching vibration of the proton motion in the (OHO)2 short hydrogen bond. Such a band has been previously observed in the spectra of the 5,50 -dibromo-3diethylaminomethyl-2,20 -biphenol and (PCP)2MTBD complex, together with a separated broad band with a maximum at about 2400 cm21 [5,12]. On the basis of
the semiempirical approach, for the asymmetric (OHO)2 bridges the band at higher wavenumbers corresponds to the 0 ! 2 transitions [13]. Thus, the broad band structure in the region of 3200 – 1600 cm 21 is caused by the Fermi resonance discussed earlier by Hadzˇi and Bratosˇ [14]. Furthermore, the appearance of such a band structure indicates the existence of a relatively strong þ NH· · ·O2 hydrogen bond. A comparable spectral feature was previously observed in the spectra of 5,50 dibromo-3-diethylaminomethyl-2,2 0 -biphenol in butyronitrile solution at a lower temperature, in the glass state as well as in the crystal [2,5]. A comparison of the spectrum of 3-diethylaminomethyl-2,20 -biphenol with that of 5,50 -dibromo-3-diethylaminomethyl2,20 -biphenol shows the slightly increasing and decreasing absorptions of the bands at higher and lower wavenumbers, respectively. The reason for this behaviour is the change of the pKa values of the hydroxyl groups. Thus, in the crystal structure of 3diethylaminomethyl-2,2 0 -biphenol the protons become more localised in the intramolecular hydrogen bonds than in the case of the dibromo derivative.
Acknowledgments Fig. 2. FT-IR spectrum of 5,50 -dibromo-3-diethylaminomethyl-2,20 biphenol in KBr pellet.
We thank Dr Jiwen Cai of Zhongshan University, China, for the diffraction measurements, and the
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S.W. Ng et al. / Journal of Molecular Structure 616 (2002) 33–36
Table 2 ˚ ) and angles (8) Bond distances (A Molecule a O1–C1 O2–C7 N1–C13 N1–C14 N1–C16 C1 –C2 C1 –C6 C2 –C3 C3 –C4 C4 –C5 C5 –C6 C6 –C13 C7 –C12 C7 –C8 C8 –C9 C9 –C10 C10–C11 C11–C12 C14–C15 C16–C17 C13–N1–C14 C13–N1–C16 C14–N1–C16 O1–C1 –C2 O1–C1 –C6 C2 –C1– C6 C3 –C2– C1 C3 –C2– C8 C1 –C2– C8 C4 –C3– C2 C5 –C4– C3 C4 –C5– C6 C5 –C6– C1 C5 –C6– C13 C1 –C6– C13 O2–C7 –C12 O2–C7 –C8 C12–C7 –C8 C7 –C8– C9 C7 –C8– C2 C9 –C8– C2 C10–C9 –C8 C11–C10–C9 C10–C11–C12 C11–C12–C7 C6 –C13–N1 N1–C14–C15 C17–C16–N1 N1· · ·O1 O2· · ·O1
1.326(3) 1.350(4) 1.491(4) 1.490(4) 1.485(4) 1.399(4) 1.411(4) 1.484(4) 1.378(5) 1.358(5) 1.370(4) 1.482(4) 1.391(5) 1.392(5) 1.403(5) 1.393(6) 1.353(7) 1.359(7) 1.493(5) 1.438(5) 113.2(2) 114.5(3) 112.3(3) 121.4(3) 118.6(3) 120.0(3) 117.0(3) 120.0(3) 122.9(3) 122.5(3) 119.5(3) 120.8(3) 120.1(3) 122.3(3) 117.6(3) 115.8(4) 122.4(3) 121.8(4) 116.3(4) 123.6(3) 120.0(4) 121.3(5) 119.8(5) 121.0(6) 119.6(5) 111.1(2) 113.8(3) 112.8(3) 2.604(3) 2.512(3)
Molecule b 1.333(4) 1.335(4) 1.484(4) 1.473(5) 1.493(5) 1.399(4) 1.406(5) 1.476(4) 1.370(5) 1.370(5) 1.369(5) 1.500(5) 1.394(5) 1.410(5) 1.380(4) 1.365(5) 1.351(6) 1.372(6) 1.494(7) 1.479(6) 113.7(4) 115.2(3) 114.3(5) 121.9(3) 117.8(3) 120.4(3) 117.3(3) 119.1(3) 123.6(3) 122.3(3) 119.9(4) 120.3(4) 119.8(3) 122.1(4) 118.0(4) 117.3(4) 123.0(4) 119.7(4) 116.6(3) 120.4(3) 122.9(3) 123.3(4) 119.4(4) 120.6(4) 120.3(4) 112.0(3) 112(1) 109.7(6) 2.593(4) 2.489(4)
University of Malay (PJP 0758/2001A) and the Polish State Committee for Scientific Research KBN, grant 3 TO9A 01817 for the financial support of this work.
References [1] B. Brzezinski, P. Radziejewski, J. Olejnik, G. Zundel, J. Mol. Struct. 323 (1994) 71. [2] B. Brzezinski, P. Radziejewski, A. Rabold, G. Zundel, J. Mol. Struct. 355 (1995) 185. [3] B. Brzezinski, H. Urjasz, G. Zundel, F. Bartl, J. Mol. Struct. 355 (1995) 185. [4] B. Brzezinski, H. Urjasz, G. Wojciechowski, G. Zundel, J. Mol. Struct. (1998) 470 see also page 335. [5] E. Bartoszak-Adamska, G. Wojciechowski, M. Jasko´lski, B. Brzezinski, J. Mol. Struct. 525 (2000) 253. [6] G.M. Sheldrick, SHELXS 86, Program for the solution of the structures, University of Go¨ttingen, Germany, 1986. [7] G.M. Sheldrick, SHELX -97, Program for the refinement of the crystal structures, University of Go¨ttingen, Germany, 1997. [8] T. Steiner, C.C. Wilson, I. Majerz, Chem. Commun. (2000) 1231. [9] D. Borgis, G. Tarjus, H. Azzouz, J. Chem. Phys. 97 (1992) 1390. [10] E.G. Weidemann, G. Zundel, Z. Naturforschug 25a (1970) 627. [11] R. Janoschek, E.G. Weidemann, G. Zundel, J. Chem. Soc. Faraday Trans. II 69 (1973) 505. [12] T. Gl⁄owiak, I. Majerz, L. Sobczyk, B. Brzezinski, G. Wojciechowski, E. Grech, J. Mol. Struct. 526 (2000) 177. [13] L. Sobczyk, Mol. Phys. Rep. 14 (1996) 19. [14] D. Hadzˇi, S. Bratosˇ, in: P. Schuster, G. Zundel, C. Sandorfy (Eds.), The Hydrogen Bond—Recent Developments in Theory and Experiments, vol. II, North Holland, Amsterdam, 1976, p. 565.
Crystal structure of 3-diethylaminomethyl-2,20 -biphenol Seik Weng Nga, Grzegorz Wojciechowskib, Bogumil Brzezinskib,* a
b
Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur, Malaysia Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60780, Poznan, Poland Received 8 March 2002; accepted 2 April 2002
Abstract Crystals of 3-diethylaminomethyl-2,20 -biphenol were examined using X-ray diffraction and FT-IR spectroscopy. Their space b ¼ 92:411ð3Þ8 and Z ¼ 8: The unit cell contains two group is P21 =c with a ¼ 7:305ð1Þ; b ¼ 13:816ð2Þ; c ¼ 29:232ð4Þ A; symmetry-independent zwitterions. The hydrogen atom of the protonated diethylaminomethyl group is linked to the negatively charged phenolate oxygen atom, which in turn is linked to the hydroxyl group by a short hydrogen bond (molecule a: molecule b: N· · ·O ¼ 2:593ð4Þ; O· · ·O ¼ 2:489ð4Þ A). N· · ·O ¼ 2:604ð3Þ; O· · ·O ¼ 2:512ð3Þ A; The OH· · ·O2 · · ·Hþ N bifurcated intramolecular hydrogen bonds are crystallographically asymmetric. The IR spectrum of the crystals confirms very well the results obtained by the X-ray study. Instead of continuous absorption, only broad bands are found indicating relatively low proton polarisability in the two types of intramolecular hydrogen bonds. q 2002 Elsevier Science B.V. All rights reserved. Keywords: 3-diethylaminomethyl-2,20 -biphenol; Intramolecular hydrogen bond; Cooperative hydrogen bond; X-ray; Crystal structure; FT-IR spectroscopy
1. Introduction In our previous papers, we have reported the preparation, X-ray and spectroscopic studies of 5,50 dibromo-3-diethylaminomethyl-2,20 -biphenol and other 5,50 -derivativates of 3-diethylaminomethyl2,20 -biphenol [1 –5]. The FTIR and 1H NMR studies of 5,50 -dibromo-3-diethylaminomethyl-2,20 -biphenol in CH2Cl2 and CH3CN solutions have demonstrated that the protons in the intramolecular hydrogen bonds undergo very fast fluctuation, whereas in the acetonitrile solution this compound was polarised to a greater extent. Because of these fluctuations a * Corresponding author. Tel.: þ48-61-829-1330; fax: þ 48-61865-8008. E-mail address: [email protected] (B. Brzezinski).
continuous absorption in the whole region was observed in the FT-IR spectra. In this paper, X-ray diffraction and FT-IR studies of a crystal of 3-diethylaminomethyl-2,20 -biphenol are reported.
2. Experimental 3-Diethylaminomethyl-2,20 -biphenol was obtained as described [2]. Colourless crystals were obtained by crystallisation from chloroform solution. The FT-IR spectrum of the sample was recorded in KBr pellets at 300 K on an FT-IR spectrometer (Bruker IFS 113v, detector MCT, resolution 2 cm21). The 13,580 room-temperature X-ray intensities for the colourless 0.41 mm £ 0.28 mm £ 0.16 mm
0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 2 8 6 0 ( 0 2 ) 0 0 1 6 5 - 5
34
S.W. Ng et al. / Journal of Molecular Structure 616 (2002) 33–36
Table 1 Atomic coordinates and equivalent isotropic temperature factors (Ueq is defined as one-third the trace of the Uij tensor) Atom
x
y
z
Ueq
O1a O2a N1a C1a C2a C3a C4a C5a C6a C7a C8a C9a C10a C11a C12a C13a C14a C15a C16a C17a O1b O2b N1b C1b C2b C3b C4b C5b C6b C7b C8b C9b C10b C11b C12b C13b C14b (57.3%) C15b (57.3%) C16b (57.3%) C17b (57.3%) C140 (42.7%) C150 (42.7%) C160 (42.7%) C170 (42.7%)
0.0365(3) 0.0051(4) 2 0.0268(4) 0.1716(4) 0.3146(4) 0.4503(5) 0.4482(6) 0.3080(6) 0.1695(5) 0.1763(6) 0.3263(5) 0.4966(6) 0.5131(9) 0.363(1) 0.1947(7) 0.0113(5) 0.1268(5) 0.1606(6) 2 0.2064(5) 2 0.3532(6) 2 0.0140(3) 0.0511(4) 0.0124(4) 2 0.1750(5) 2 0.3014(5) 2 0.4655(5) 2 0.5052(6) 2 0.3814(6) 2 0.2166(6) 2 0.0985(6) 2 0.2689(5) 2 0.4108(5) 2 0.3940(7) 2 0.2315(9) 2 0.0830(7) 2 0.0717(6) 2 0.101(1) 2 0.055(3) 0.2101(8) 0.237(1) 2 0.134(1) 2 0.066(2) 0.153(1) 0.322(2)
0.9755(1) 0.8212(2) 1.1468(2) 1.0138(2) 0.9568(2) 1.0040(3) 1.1025(4) 1.1565(3) 1.1144(2) 0.7890(3) 0.8509(3) 0.8074(4) 0.7076(5) 0.6505(4) 0.6893(3) 1.1705(2) 1.1726(2) 1.2789(3) 1.1821(3) 1.1150(4) 0.2804(2) 0.4281(2) 0.1492(2) 0.3082(2) 0.3609(2) 0.3851(2) 0.3595(3) 0.3068(3) 0.2812(3) 0.4258(2) 0.3908(2) 0.3910(2) 0.4262(3) 0.4626(3) 0.4625(3) 0.2298(3) 0.0612(5) 2 0.001(1) 0.1310(5) 0.1197(6) 0.0739(6) 0.0018(9) 0.0968(7) 0.152(1)
0.0719(1) 0.1163(1) 0.0377(1) 0.0977(1) 0.1162(1) 0.1429(1) 0.1504(1) 0.1321(1) 0.1060(1) 0.1096(1) 0.1086(1) 0.1019(1) 0.0967(2) 0.0992(2) 0.1048(1) 0.0869(1) 0.0080(1) 0.0047(1) 0.0186(1) 0.0256(2) 0.1860(1) 0.1407(1) 0.2494(1) 0.2014(1) 0.1741(1) 0.1931(1) 0.2369(1) 0.2632(1) 0.2462(1) 0.1129(2) 0.1266(1) 0.0939(1) 0.0506(1) 0.0385(2) 0.0688(2) 0.2747(1) 0.2467(4) 0.2069(6) 0.2613(2) 0.3114(2) 0.2368(5) 0.2033(4) 0.2818(4) 0.2776(6)
0.074(1) 0.087(1) 0.069(1) 0.066(1) 0.071(1) 0.096(1) 0.107(1) 0.091(1) 0.071(1) 0.077(1) 0.075(1) 0.109(1) 0.139(2) 0.142(2) 0.104(1) 0.080(1) 0.079(1) 0.117(1) 0.098(1) 0.149(2) 0.098(1) 0.110(1) 0.099(1) 0.077(1) 0.071(1) 0.081(1) 0.102(1) 0.101(1) 0.088(1) 0.086(1) 0.071(1) 0.082(1) 0.101(1) 0.115(2) 0.108(1) 0.119(1) 0.076(3) 0.163(8) 0.089(2) 0.112(3) 0.086(5) 0.061(4) 0.145(5) 0.171(6)
specimen were collected on a Siemens CCD areadetector diffractometer (Mo Ka radiation, The data were averaged for 5715 l ¼ 0:71073 A). reflections, of which 2179 were observable. The
structure was solved by direct methods, and it was refined on F 2 to R ¼ 0:051: The b molecule is disordered in the diethylaminomethyl group, and the two components refined to a 57:43 ratio. The hydrogen atom of protonated diethylaminomethyl group in the molecule a and the hydroxyl hydrogen atoms of both molecules are located and refined; the hydrogen atom of the protonated diethylaminomethyl group in the molecule b was placed in a geometrically sensible position. Crystal data: C17H21NO2, FW ¼ 271:35; monoclinic, P21 =c; a ¼ 7:305ð1Þ; b ¼ 13:816ð2Þ; c ¼ b ¼ 92:411ð3Þ8; V ¼ 2947:8ð7Þ A 3; Z ¼ 29:232ð4Þ A; 23 8; r ¼ 1:223 g cm ; Fð000Þ ¼ 1168; m¼ 0:080 mm21 :
3. Results and discussion 3.1. Description of the structure Fractional atomic coordinates and equivalent isotropic displacement coefficients are listed in Table 1. An ORTEP [6,7] plot of the molecule with the atom numbering scheme is presented in Fig. 1. The geometry of the molecule is given in Table 2. In the unit cell, there are two symmetry-independent zwitterions (a and b). In the molecule a, the two rings are tilted by 40.0(1)8 and in the molecule b, the tilt is 39.1(1)8. The –CH2N(C2H5)2 amino group as a relatively strong base causes the deprotonation of the hydroxyl group at the same ring across a short intramolecular Oð1Þ2 · · ·Nþ ð1Þ hydrogen bond. The hydrogen atom of the protonated diethylaminomethyl group is linked to the negatively charged phenolate oxygen atom, which in turn is linked to the hydroxyl group by a short hydrogen bond [molecule a: N· · ·O ¼ molecule b: N· · ·O ¼ 2:604ð3Þ; O· · ·O ¼ 2:512ð3Þ A; Both OH· · ·O2 · · · 2:593ð4Þ; O· · ·O ¼ 2:489ð4Þ A]. þ H N bifurcated intramolecular hydrogen bonds are crystallographically asymmetric. The Nþ – H· · ·2 O hydrogen bonds are only slightly weaker than the N· · ·H – O one observed in the complex of 2methylpiridine with pentachlorophenol [2.588(3)] [8]. 3.2. FT-IR spectrum The IR spectrum of 3-diethylaminomethyl-2,20 biphenol crystals is shown in Fig. 2. In this spectrum,
S.W. Ng et al. / Journal of Molecular Structure 616 (2002) 33–36
35
Fig. 1. ORTEP plot of one of the two independent molecules at the 50% probability level. Hydrogen atoms are drawn as spheres of arbitrary radii.
in contrast to that of 3-diethylaminomethyl-2,20 biphenol in acetonitrile, there is no continuous absorption in the region of 3000– 400 cm21, but only two bands in the region of 3200 –1600 cm21 with maxima at about 2400 and 1820 cm21, respectively, as well as a broad intense band with a maximum at about 1220 cm21. This hydrogen bonded system does not show very large proton polarisability, so it does not contribute to the so-called Zundel’s polarisability [9 –11]. The broad band with a maximum at about 1220 cm21 can be assigned to the stretching vibration of the proton motion in the (OHO)2 short hydrogen bond. Such a band has been previously observed in the spectra of the 5,50 -dibromo-3diethylaminomethyl-2,20 -biphenol and (PCP)2MTBD complex, together with a separated broad band with a maximum at about 2400 cm21 [5,12]. On the basis of
the semiempirical approach, for the asymmetric (OHO)2 bridges the band at higher wavenumbers corresponds to the 0 ! 2 transitions [13]. Thus, the broad band structure in the region of 3200 – 1600 cm 21 is caused by the Fermi resonance discussed earlier by Hadzˇi and Bratosˇ [14]. Furthermore, the appearance of such a band structure indicates the existence of a relatively strong þ NH· · ·O2 hydrogen bond. A comparable spectral feature was previously observed in the spectra of 5,50 dibromo-3-diethylaminomethyl-2,2 0 -biphenol in butyronitrile solution at a lower temperature, in the glass state as well as in the crystal [2,5]. A comparison of the spectrum of 3-diethylaminomethyl-2,20 -biphenol with that of 5,50 -dibromo-3-diethylaminomethyl2,20 -biphenol shows the slightly increasing and decreasing absorptions of the bands at higher and lower wavenumbers, respectively. The reason for this behaviour is the change of the pKa values of the hydroxyl groups. Thus, in the crystal structure of 3diethylaminomethyl-2,2 0 -biphenol the protons become more localised in the intramolecular hydrogen bonds than in the case of the dibromo derivative.
Acknowledgments Fig. 2. FT-IR spectrum of 5,50 -dibromo-3-diethylaminomethyl-2,20 biphenol in KBr pellet.
We thank Dr Jiwen Cai of Zhongshan University, China, for the diffraction measurements, and the
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S.W. Ng et al. / Journal of Molecular Structure 616 (2002) 33–36
Table 2 ˚ ) and angles (8) Bond distances (A Molecule a O1–C1 O2–C7 N1–C13 N1–C14 N1–C16 C1 –C2 C1 –C6 C2 –C3 C3 –C4 C4 –C5 C5 –C6 C6 –C13 C7 –C12 C7 –C8 C8 –C9 C9 –C10 C10–C11 C11–C12 C14–C15 C16–C17 C13–N1–C14 C13–N1–C16 C14–N1–C16 O1–C1 –C2 O1–C1 –C6 C2 –C1– C6 C3 –C2– C1 C3 –C2– C8 C1 –C2– C8 C4 –C3– C2 C5 –C4– C3 C4 –C5– C6 C5 –C6– C1 C5 –C6– C13 C1 –C6– C13 O2–C7 –C12 O2–C7 –C8 C12–C7 –C8 C7 –C8– C9 C7 –C8– C2 C9 –C8– C2 C10–C9 –C8 C11–C10–C9 C10–C11–C12 C11–C12–C7 C6 –C13–N1 N1–C14–C15 C17–C16–N1 N1· · ·O1 O2· · ·O1
1.326(3) 1.350(4) 1.491(4) 1.490(4) 1.485(4) 1.399(4) 1.411(4) 1.484(4) 1.378(5) 1.358(5) 1.370(4) 1.482(4) 1.391(5) 1.392(5) 1.403(5) 1.393(6) 1.353(7) 1.359(7) 1.493(5) 1.438(5) 113.2(2) 114.5(3) 112.3(3) 121.4(3) 118.6(3) 120.0(3) 117.0(3) 120.0(3) 122.9(3) 122.5(3) 119.5(3) 120.8(3) 120.1(3) 122.3(3) 117.6(3) 115.8(4) 122.4(3) 121.8(4) 116.3(4) 123.6(3) 120.0(4) 121.3(5) 119.8(5) 121.0(6) 119.6(5) 111.1(2) 113.8(3) 112.8(3) 2.604(3) 2.512(3)
Molecule b 1.333(4) 1.335(4) 1.484(4) 1.473(5) 1.493(5) 1.399(4) 1.406(5) 1.476(4) 1.370(5) 1.370(5) 1.369(5) 1.500(5) 1.394(5) 1.410(5) 1.380(4) 1.365(5) 1.351(6) 1.372(6) 1.494(7) 1.479(6) 113.7(4) 115.2(3) 114.3(5) 121.9(3) 117.8(3) 120.4(3) 117.3(3) 119.1(3) 123.6(3) 122.3(3) 119.9(4) 120.3(4) 119.8(3) 122.1(4) 118.0(4) 117.3(4) 123.0(4) 119.7(4) 116.6(3) 120.4(3) 122.9(3) 123.3(4) 119.4(4) 120.6(4) 120.3(4) 112.0(3) 112(1) 109.7(6) 2.593(4) 2.489(4)
University of Malay (PJP 0758/2001A) and the Polish State Committee for Scientific Research KBN, grant 3 TO9A 01817 for the financial support of this work.
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