- Email: [email protected]
The intermolecular attraction of 3H-2-imino-4-methylbenzothiazoline in crystal structure
Journal of Molecular Structure 641 (2002) 147–152 www.elsevier.com/locate/molstruc
The intermolecular attraction of 3H-2-imino-4-methylbenzothiazoline in crystal structure Heng-Shan Donga,*, Bin Quanb, Hui-Qian Tianb a
National Laboratory of Applied Organic Chemistry, Institute of Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, People’s Republic of China b Department of Chemistry, Guansu Education College, Lanzhou, Gansu 730000, People’s Republic of China Received 17 December 2001; revised 18 March 2002; accepted 18 March 2002
Abstract 3H-2-imino-4-methylbenzothiazoline was obtained from o-methylaniline to form 4. The yielded product 6 was confirmed by Elemental analyses, NMR, MS, IR spectra and X-ray crystallography. Compound 6, C8H8N2S, Mr ¼ 164:23; crystallized in the a ¼ 89:975ð14Þ; monoclinic space group P21 =c with unit cell parameters a ¼ 4:0949ð15Þ; b ¼ 11:790ð2Þ; c ¼ 15:837ð2Þ A; 3 ; Z ¼ 4; Dm ¼ 1:436 Mgm23 : The intermolecular attraction of 3H-2-iminob ¼ 96:510ð19Þ; g ¼ 90:09ð2Þ8; V ¼ 759:7ð3Þ A 4-methylbenzothiazoline in crystal structure is discussed. q 2002 Published by Elsevier Science B.V. Keywords: Benzothiazole derivative; Intermolecular attraction; 3H-2-Imino-4-methylbenzothiazoline; Crystal structure
1. Introduction Tricyclazole is one of the benzothiazole derivatives, which is well known for synthesizing many a compound with its ring system beading diverse biological activities such as application as potent antibacterials [1,2] and fungicides for the control of Piricularia oryzae in the prevention of rice blast [3]. Therefore, it was planned to investigate a system, which combines these biological components in a ring to give a compact system for screening their biologic activities. Recently, when we synthesized several novel 5-methyl-3-substituted-1,2,4-triazolo[3,4b]benzothiazoles from o-methylaniline with various aromatic carbonic acids, we obtained the compound 3H-2-imino-4-methylbenzothiazoline 6. The yielded * Corresponding author. E-mail address: [email protected] (H.S. Dong).
product 6 was investigated with Elemental analyses— NMR, MS, IR techniques and X-ray crystallography. Compound 6, C8H8N2S, Mr ¼ 164:23; crystallized in the monoclinic space group P21 =c with unit cell parameters a ¼ 4:0949ð15Þ; b ¼ 11:790ð2Þ; c ¼ a ¼ 89:975ð14Þ; b ¼ 96:510ð19Þ; g ¼ 15:837ð2Þ A; 3; 90:09ð2Þ8; V ¼ 759:7ð3Þ A Z ¼ 4; Dm ¼ 23 1:436 Mg m : The structure of imino-4-methylbenzothiazoline is stabilized by an N – H· · ·N hydrogen bond and the intermolecular attraction in crystal structure. The synthesis pathway of compound 6 is shown in Scheme 1.
2. Results and discussion The structure of the title compound is shown in Fig. 1. The unit cell parameters of the title compound
0022-2860/02/$ - see front matter q 2002 Published by Elsevier Science B.V. PII: S 0 0 2 2 - 2 8 6 0 ( 0 2 ) 0 0 1 2 9 - 1
148
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
Scheme 1. The synthesis routes of compound 6.
Fig. 1. ORTEP drawing of the title compound showing the atom numbering scheme.
are shown in Fig. 2. In recent years, the synthesis and characteristics of 7-methyl-3-substituted-1,2,4-triazolo [3,4-b]benzothiazoles [4] and 5-methyl-3-(2phenylquinoline-4-yl)-1,2,4-triazolo[3,4-b]benzothiazole derivatives [5] have been investigated. These heterocyclic compounds contain benzothiazole rings. Recently, the substituted groups at the two positions can conjugate with the benzothiazole nucleus giving it new characteristics as is given in recent studies [6,7]. The existence of intermolecular attraction in 3H-2imino-4-methylbenzothiazoline in crystal structure is very much interesting.
IR absorption strip of 6 at 3178, 3117 cm21 is assigned to its N – H; and a characteristic strip of nCyN appears at 1670 cm21. It is similar to the allied system [7]. The nC – S – C absorption strip of compound 6 appears at 699 cm21. In 1H NMR spectra, comparing 6, we found that after cyclization the evident change is that the signals of yN –H protons are at d 10.649 ppm. The chemical shift of the aromatic ring methyl group shows in the d 2.443 ppm. The chemical shift of the aromatic ring on the benzothiazoline ring in compound 6 occurs at d 7.054 – 7.256 ppm.
Fig. 2. The unit cell parameters of the title compound.
Compound 6 Color/shape Formula weight Temperature (8C) Crystal system Space group Cell constants ˚) a (A ˚) b (A ˚) c (A a (deg) b (deg) g (deg) ˚ 3) Volume (A Formula units/units cell Dcalc (g cm23) Fð000Þ Absorption coefficient (m m21)
C8H8N2S Colorless/prism 164.23 20 (293 K) Monoclinic P21 =c 4.0949(15) 11.790(2) 15.837(2) 89.975(14) 96.510(19) 90.09(2) 759.7(3) 4 1.436 344 0.352
Diffractometer/scan Enraf–Nonius CAD4, v=2u Radiation, graphite monochromator Mo Ka Reflections for cell measurement and u range (deg) Index ranges Standard reflections Reflections measured Reflection observed [1 . 2s(I)] Maximum value of u(deg) Computing Data collection Cell refinement Data reduction Structure solution Structure refinement Data/Restrains/Parameters Goodness-of-fit on F2 Final R indices Largest diff. peak and hole
˚ 23 28 and 20.082 eA l ¼ 0:71073 A 25, 0–25 0 # h # 4; 0 # k # 14; 218 # l # 18 895 566 998 ðRint ¼ 0:041Þ 25.02 CAD4 CAD4 PCSDP SHELXS -97 SHELXL -97
6649/0/523 1.083 R1 ¼ 0:0417; wR2 ¼ 0:0788 0.128 and 20.082
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
Table 1 Crystal data and summary of data collection and structure refinement
149
150
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
Table 2 The fractional coordinates and means temperature factors with estimated standard deviations for non-hydrogen atoms
S1 S2 N1 N2 N3 N4 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16
X
Y
Z
U
20.0191(16) 0.5140(17) 20.001(6) 0.483(4) 0.287(7) 0.233(6) 20.353(5) 20.448(5) 20.443(5) 20.263(4) 20.148(5) 20.185(4) 20.194(3) 0.102(4) 0.391(7) 0.769(4) 0.908(5) 0.972(7) 0.835(9) 0.700(4) 0.652(4) 0.686(4)
0.5024(4) 0.3319(5) 0.527(2) 0.3056(11) 0.3580(18) 0.4754(18) 0.7097(17) 0.7961(19) 0.805(2) 0.7095(14) 0.6231(17) 0.6288(16) 0.6917(12) 0.4528(15) 0.382(2) 0.1246(14) 0.0397(17) 0.030(2) 0.119(3) 0.2172(16) 0.2134(16) 0.1340(16)
0.2111(4) 20.2108(3) 0.0458(11) 20.0484(12) 0.1058(10) 20.1057(15) 0.1970(14) 0.1468(18) 0.055(2) 0.0192(10) 0.0772(15) 0.1599(14) 20.0775(8) 0.1092(14) 20.1144(11) 20.0239(18) 20.0591(11) 20.145(2) 20.193(2) 20.1611(10) 20.0730(8) 0.0743(10)
0.0754(16) 0.0813(18) 0.077(5) 0.057(4) 0.085(6) 0.080(5) 0.062(4) 0.086(8) 0.084(8) 0.055(4) 0.066(5) 0.060(4) 0.046(3) 0.065(5) 0.079(6) 0.069(6) 0.064(4) 0.099(9) 0.090(8) 0.057(4) 0.051(4) 0.060(4)
In the mass spectra of 6, the molecular ion peaks are weak and the M þ 1 peak is strong (100%). Compound 6 exhibits some important ion perks at m=z 137; 122; 110; 109; 104; 93; 84; 77; 69; 65; 51; 45; 39: Single crystals were selected and mounted on the tip of a glass fiber. Preliminary examination and data collection were performed with Mo Ka radiation ðl ¼ on an Enraf –Nonius CAD4 computer 0:71073 AÞ controlled kappa axis diffractometer operating in the v=2u scanning mode using the crystal. The structure was determined by direct methods [SHELXS -97 (Sheldrick, 1990)] and refined by full covariance matrix methods [SHELXL -97 (Sheldrick, 1997)]. The crystal data and the refinement detail are given in Table 1. The structure of the title compound is shown in Fig. 1. The fractional coordinates and mean temperature factors with estimated standard deviations for non-hydrogen atoms are listed in Table 2 and selected bond lengths are given in Table 3; selected bond angles are given in Table 4. The geometric calculations were performed using the program SHELX -97. The central ring system in the present compound
was already determined. The benzothiazole ring system is planar. The bond lengths indicate a degree of delocalization around the ring system with the three CyN bonds ranging from N1 –C8 1.36(3), N2 – C15 ˚ . The bond 1.37(3) to N1 –C5 and N2 – C9 1.40(3) A lengths N3 – C8 1.36(3), N4 –C9 1.29(4), S1 – C6 1.79(2), S1 –C8 1.84(2), S2– C14 1.70(2), S2 – C9 ˚ are agreement with the values reported 1.765(17) A for benzothiazole by Fehlmann [8] (the bond lengths ˚ , N2 – C7 1.381 A ˚ , S1 –C6 1.739 A ˚, N2 –C8 1.297 A ˚ ˚ S1– C8 1.763 A). The bond lengths N2 –C8 1.297 A ˚ [8] and N2 –C8 1.373(4) A are between the bond lengths of CyN and C –N. The results, therefore, show that, although the cyclization of o-tolylthiourea gives 2-amino-4-methylbenzothiazole, isomerization of 2-amino-4-methylbenzothiazole takes place with much ease. Leading to the isolated 2-imino-4methylbenzothiazoline does so only on prolonged heating. This result is because the structure of the imino-4-methylbenzothiazoline is stabilized by an N – H· · ·N hydrogen bond. The structure of the title compound is shown in Scheme 2.
Table 3 ˚) Selected bond lengths (A S1 S1 S2 S2 N1 N1 N2 N2 N3 N4 C1 C1 C2 C3 C4 C4 C5 C10 C10 C10 C11 C12 C13 C14
C6 C8 C14 C9 C8 C5 C15 C9 C8 C9 C2 C6 C3 C4 C5 C7 C6 C11 C15 C16 C12 C13 C14 C15
1.79(2) 1.84(2) 1.70(2) 1.765(17) 1.36(3) 1.40(3) 1.37(3) 1.40(3) 1.36(3) 1.29(4) 1.32(4) 1.35(3) 1.46(5) 1.49(3) 1.42(3) 1.601(17) 1.34(3) 1.31(3) 1.36(3) 1.63(3) 1.41(5) 1.38(5) 1.41(4) 1.431(19)
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
151
in KBr discs using a Nicolet 170SX FT-IR spectrometer. 1H NMR spectroscopy was recorded at room temperature at 400.13 MHz on a Bruker AM 400 instrument. Elemental analyses were carried out on a Yanaco CHN Corder MT-3 analyzer. 3.1. The o-tolylthiourea 3 is prepared [9] Scheme 2. The structure of 3H-2-imino-4-methylbenzothiazoline 6.
3. Experiment Melting points were determined on a Kofler melting point apparatus and are uncorrected. The mass spectrum was performed on a HP-5988A spectrometer (EI at 70 eV). IR spectra were obtained Table 4 Selected bond angles (deg) C6 C14 C8 C15 C2 C1 C2 C5 C5 C3 C6 C6 N1 C5 C5 C1 N1 N1 N3 N4 N4 N2 C11 C11 C15 C10 C13 C12 C13 C13 C15 C10 C10 N2
S1 S2 N1 N2 C1 C2 C3 C4 C4 C4 C5 C5 C5 C6 C6 C6 C8 C8 C8 C9 C9 C9 C10 C10 C10 C11 C12 C13 C14 C14 C14 C15 C15 C15
C8 C9 C5 C9 C6 C3 C4 C3 C7 C7 N1 C4 C4 C1 S1 S1 N3 S1 S1 N2 S2 S2 C15 C16 C16 C12 C11 C14 C15 S2 S2 N2 C14 C14
89.7(10) 91.4(10) 111.7(18) 113.8(16) 114.3(19) 128.1(15) 113(2) 116.0(17) 116.3(14) 127.7(18) 119(2) 122.1(17) 118.5(17) 126(2) 108.7(15) 125.2(18) 129(2) 110.5(15) 120.4(15) 124.4(18) 125.2(17) 110.4(17) 119(2) 127.2(18) 113.3(17) 127.4(18) 111(2) 125(3) 116(2) 131.3(19) 111.8(13) 127.3(16) 120.2(19) 112.5(15)
Mp 155 –156 8C (Lit. mp 155 –156 8C [9]). 3.2. The hydrobromide of 2-amino-4methylbenzothiazole 4 is prepared [9] Mp 253 –254 8C (Lit. 254 8C [9]). 3.3. The 3H-2-imino-4-methylbenzothiazoline 6 A mixture of the hydrobromide of 2-amino-4methylbenzothiazole 4 (10 g, 0.41 mol), and hydrazine hydrate 85% (0.055 mol) in 38 ml of glycol was refluxed (165 – 175 8C) while stirring for 14 h. The color of the reaction mixture changed to green, and gave a homogeneous solution. A white solid was precipitated at the end of the reflux period. The mixture was cooled and the product was filtered, washed with water, air-dried and recrystallized from ethanol to give white prism crystal of 6. It gave a 10.4 g, mp 139– 140 8C product. The purified product was dissolved in ethyl acetate: petroleum ether: ethanol solution. The crystal was obtained after 7 days by evaporation of the solvent.
Acknowledgments The authors wish to acknowledge the support to this project by NNSFC (chuangxin qunti, 2002-001), University Key Teacher by the Ministry of Education and Lanzhou University NLAOC.
References [1] A. Gvozdjakova, J. Habsudova, K. Kufcakova, Stud. Org. Chem. (Amsterdam) 35 (1988) 297 Chem. Abstr. 110 (1989) 11474n. [2] D.S. Deshpande, Acta Cienc Indica (Ser.) Chem. 6 (1980) 80 Chem. Abstr. 94 (1981) 65568b.
152
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
[3] R.K. Acngill, N. Matsuura, F. Tabuchi, European Patent 213 814, 1987, (Chem. Abstr. 107 (1987) 178600m). [4] H.-S. Dong, J.-R. Zhang, Y.-B. Tang, X.-R. Mao, B. Quan, J. Chin. Chem. Soc. 48 (2001) 783. [5] H.-S. Dong, B. Quan, E.-F. Chai, X.-R. Mao, J. Mol. Struct. 608 (2002) 41–47.
[6] B.S. Holla, A. D’Souza, B. Kalluraya, J. Indian Chem. Soc. 68 (1991) 250. [7] A. Miyashita, I. Nagasaki, A. Kawano, Y. Suzuki, K.-I. Iwamoto, T. Higashino, Heterocycles 45 (1997) 745. [8] M. Fehlmann, Acta Cryst. B26 (1970) 1736. [9] C.E. Dalgliesh, F.G. Mann, J. Chem. Soc. (1945) 900.
The intermolecular attraction of 3H-2-imino-4-methylbenzothiazoline in crystal structure Heng-Shan Donga,*, Bin Quanb, Hui-Qian Tianb a
National Laboratory of Applied Organic Chemistry, Institute of Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, People’s Republic of China b Department of Chemistry, Guansu Education College, Lanzhou, Gansu 730000, People’s Republic of China Received 17 December 2001; revised 18 March 2002; accepted 18 March 2002
Abstract 3H-2-imino-4-methylbenzothiazoline was obtained from o-methylaniline to form 4. The yielded product 6 was confirmed by Elemental analyses, NMR, MS, IR spectra and X-ray crystallography. Compound 6, C8H8N2S, Mr ¼ 164:23; crystallized in the a ¼ 89:975ð14Þ; monoclinic space group P21 =c with unit cell parameters a ¼ 4:0949ð15Þ; b ¼ 11:790ð2Þ; c ¼ 15:837ð2Þ A; 3 ; Z ¼ 4; Dm ¼ 1:436 Mgm23 : The intermolecular attraction of 3H-2-iminob ¼ 96:510ð19Þ; g ¼ 90:09ð2Þ8; V ¼ 759:7ð3Þ A 4-methylbenzothiazoline in crystal structure is discussed. q 2002 Published by Elsevier Science B.V. Keywords: Benzothiazole derivative; Intermolecular attraction; 3H-2-Imino-4-methylbenzothiazoline; Crystal structure
1. Introduction Tricyclazole is one of the benzothiazole derivatives, which is well known for synthesizing many a compound with its ring system beading diverse biological activities such as application as potent antibacterials [1,2] and fungicides for the control of Piricularia oryzae in the prevention of rice blast [3]. Therefore, it was planned to investigate a system, which combines these biological components in a ring to give a compact system for screening their biologic activities. Recently, when we synthesized several novel 5-methyl-3-substituted-1,2,4-triazolo[3,4b]benzothiazoles from o-methylaniline with various aromatic carbonic acids, we obtained the compound 3H-2-imino-4-methylbenzothiazoline 6. The yielded * Corresponding author. E-mail address: [email protected] (H.S. Dong).
product 6 was investigated with Elemental analyses— NMR, MS, IR techniques and X-ray crystallography. Compound 6, C8H8N2S, Mr ¼ 164:23; crystallized in the monoclinic space group P21 =c with unit cell parameters a ¼ 4:0949ð15Þ; b ¼ 11:790ð2Þ; c ¼ a ¼ 89:975ð14Þ; b ¼ 96:510ð19Þ; g ¼ 15:837ð2Þ A; 3; 90:09ð2Þ8; V ¼ 759:7ð3Þ A Z ¼ 4; Dm ¼ 23 1:436 Mg m : The structure of imino-4-methylbenzothiazoline is stabilized by an N – H· · ·N hydrogen bond and the intermolecular attraction in crystal structure. The synthesis pathway of compound 6 is shown in Scheme 1.
2. Results and discussion The structure of the title compound is shown in Fig. 1. The unit cell parameters of the title compound
0022-2860/02/$ - see front matter q 2002 Published by Elsevier Science B.V. PII: S 0 0 2 2 - 2 8 6 0 ( 0 2 ) 0 0 1 2 9 - 1
148
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
Scheme 1. The synthesis routes of compound 6.
Fig. 1. ORTEP drawing of the title compound showing the atom numbering scheme.
are shown in Fig. 2. In recent years, the synthesis and characteristics of 7-methyl-3-substituted-1,2,4-triazolo [3,4-b]benzothiazoles [4] and 5-methyl-3-(2phenylquinoline-4-yl)-1,2,4-triazolo[3,4-b]benzothiazole derivatives [5] have been investigated. These heterocyclic compounds contain benzothiazole rings. Recently, the substituted groups at the two positions can conjugate with the benzothiazole nucleus giving it new characteristics as is given in recent studies [6,7]. The existence of intermolecular attraction in 3H-2imino-4-methylbenzothiazoline in crystal structure is very much interesting.
IR absorption strip of 6 at 3178, 3117 cm21 is assigned to its N – H; and a characteristic strip of nCyN appears at 1670 cm21. It is similar to the allied system [7]. The nC – S – C absorption strip of compound 6 appears at 699 cm21. In 1H NMR spectra, comparing 6, we found that after cyclization the evident change is that the signals of yN –H protons are at d 10.649 ppm. The chemical shift of the aromatic ring methyl group shows in the d 2.443 ppm. The chemical shift of the aromatic ring on the benzothiazoline ring in compound 6 occurs at d 7.054 – 7.256 ppm.
Fig. 2. The unit cell parameters of the title compound.
Compound 6 Color/shape Formula weight Temperature (8C) Crystal system Space group Cell constants ˚) a (A ˚) b (A ˚) c (A a (deg) b (deg) g (deg) ˚ 3) Volume (A Formula units/units cell Dcalc (g cm23) Fð000Þ Absorption coefficient (m m21)
C8H8N2S Colorless/prism 164.23 20 (293 K) Monoclinic P21 =c 4.0949(15) 11.790(2) 15.837(2) 89.975(14) 96.510(19) 90.09(2) 759.7(3) 4 1.436 344 0.352
Diffractometer/scan Enraf–Nonius CAD4, v=2u Radiation, graphite monochromator Mo Ka Reflections for cell measurement and u range (deg) Index ranges Standard reflections Reflections measured Reflection observed [1 . 2s(I)] Maximum value of u(deg) Computing Data collection Cell refinement Data reduction Structure solution Structure refinement Data/Restrains/Parameters Goodness-of-fit on F2 Final R indices Largest diff. peak and hole
˚ 23 28 and 20.082 eA l ¼ 0:71073 A 25, 0–25 0 # h # 4; 0 # k # 14; 218 # l # 18 895 566 998 ðRint ¼ 0:041Þ 25.02 CAD4 CAD4 PCSDP SHELXS -97 SHELXL -97
6649/0/523 1.083 R1 ¼ 0:0417; wR2 ¼ 0:0788 0.128 and 20.082
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
Table 1 Crystal data and summary of data collection and structure refinement
149
150
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
Table 2 The fractional coordinates and means temperature factors with estimated standard deviations for non-hydrogen atoms
S1 S2 N1 N2 N3 N4 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16
X
Y
Z
U
20.0191(16) 0.5140(17) 20.001(6) 0.483(4) 0.287(7) 0.233(6) 20.353(5) 20.448(5) 20.443(5) 20.263(4) 20.148(5) 20.185(4) 20.194(3) 0.102(4) 0.391(7) 0.769(4) 0.908(5) 0.972(7) 0.835(9) 0.700(4) 0.652(4) 0.686(4)
0.5024(4) 0.3319(5) 0.527(2) 0.3056(11) 0.3580(18) 0.4754(18) 0.7097(17) 0.7961(19) 0.805(2) 0.7095(14) 0.6231(17) 0.6288(16) 0.6917(12) 0.4528(15) 0.382(2) 0.1246(14) 0.0397(17) 0.030(2) 0.119(3) 0.2172(16) 0.2134(16) 0.1340(16)
0.2111(4) 20.2108(3) 0.0458(11) 20.0484(12) 0.1058(10) 20.1057(15) 0.1970(14) 0.1468(18) 0.055(2) 0.0192(10) 0.0772(15) 0.1599(14) 20.0775(8) 0.1092(14) 20.1144(11) 20.0239(18) 20.0591(11) 20.145(2) 20.193(2) 20.1611(10) 20.0730(8) 0.0743(10)
0.0754(16) 0.0813(18) 0.077(5) 0.057(4) 0.085(6) 0.080(5) 0.062(4) 0.086(8) 0.084(8) 0.055(4) 0.066(5) 0.060(4) 0.046(3) 0.065(5) 0.079(6) 0.069(6) 0.064(4) 0.099(9) 0.090(8) 0.057(4) 0.051(4) 0.060(4)
In the mass spectra of 6, the molecular ion peaks are weak and the M þ 1 peak is strong (100%). Compound 6 exhibits some important ion perks at m=z 137; 122; 110; 109; 104; 93; 84; 77; 69; 65; 51; 45; 39: Single crystals were selected and mounted on the tip of a glass fiber. Preliminary examination and data collection were performed with Mo Ka radiation ðl ¼ on an Enraf –Nonius CAD4 computer 0:71073 AÞ controlled kappa axis diffractometer operating in the v=2u scanning mode using the crystal. The structure was determined by direct methods [SHELXS -97 (Sheldrick, 1990)] and refined by full covariance matrix methods [SHELXL -97 (Sheldrick, 1997)]. The crystal data and the refinement detail are given in Table 1. The structure of the title compound is shown in Fig. 1. The fractional coordinates and mean temperature factors with estimated standard deviations for non-hydrogen atoms are listed in Table 2 and selected bond lengths are given in Table 3; selected bond angles are given in Table 4. The geometric calculations were performed using the program SHELX -97. The central ring system in the present compound
was already determined. The benzothiazole ring system is planar. The bond lengths indicate a degree of delocalization around the ring system with the three CyN bonds ranging from N1 –C8 1.36(3), N2 – C15 ˚ . The bond 1.37(3) to N1 –C5 and N2 – C9 1.40(3) A lengths N3 – C8 1.36(3), N4 –C9 1.29(4), S1 – C6 1.79(2), S1 –C8 1.84(2), S2– C14 1.70(2), S2 – C9 ˚ are agreement with the values reported 1.765(17) A for benzothiazole by Fehlmann [8] (the bond lengths ˚ , N2 – C7 1.381 A ˚ , S1 –C6 1.739 A ˚, N2 –C8 1.297 A ˚ ˚ S1– C8 1.763 A). The bond lengths N2 –C8 1.297 A ˚ [8] and N2 –C8 1.373(4) A are between the bond lengths of CyN and C –N. The results, therefore, show that, although the cyclization of o-tolylthiourea gives 2-amino-4-methylbenzothiazole, isomerization of 2-amino-4-methylbenzothiazole takes place with much ease. Leading to the isolated 2-imino-4methylbenzothiazoline does so only on prolonged heating. This result is because the structure of the imino-4-methylbenzothiazoline is stabilized by an N – H· · ·N hydrogen bond. The structure of the title compound is shown in Scheme 2.
Table 3 ˚) Selected bond lengths (A S1 S1 S2 S2 N1 N1 N2 N2 N3 N4 C1 C1 C2 C3 C4 C4 C5 C10 C10 C10 C11 C12 C13 C14
C6 C8 C14 C9 C8 C5 C15 C9 C8 C9 C2 C6 C3 C4 C5 C7 C6 C11 C15 C16 C12 C13 C14 C15
1.79(2) 1.84(2) 1.70(2) 1.765(17) 1.36(3) 1.40(3) 1.37(3) 1.40(3) 1.36(3) 1.29(4) 1.32(4) 1.35(3) 1.46(5) 1.49(3) 1.42(3) 1.601(17) 1.34(3) 1.31(3) 1.36(3) 1.63(3) 1.41(5) 1.38(5) 1.41(4) 1.431(19)
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
151
in KBr discs using a Nicolet 170SX FT-IR spectrometer. 1H NMR spectroscopy was recorded at room temperature at 400.13 MHz on a Bruker AM 400 instrument. Elemental analyses were carried out on a Yanaco CHN Corder MT-3 analyzer. 3.1. The o-tolylthiourea 3 is prepared [9] Scheme 2. The structure of 3H-2-imino-4-methylbenzothiazoline 6.
3. Experiment Melting points were determined on a Kofler melting point apparatus and are uncorrected. The mass spectrum was performed on a HP-5988A spectrometer (EI at 70 eV). IR spectra were obtained Table 4 Selected bond angles (deg) C6 C14 C8 C15 C2 C1 C2 C5 C5 C3 C6 C6 N1 C5 C5 C1 N1 N1 N3 N4 N4 N2 C11 C11 C15 C10 C13 C12 C13 C13 C15 C10 C10 N2
S1 S2 N1 N2 C1 C2 C3 C4 C4 C4 C5 C5 C5 C6 C6 C6 C8 C8 C8 C9 C9 C9 C10 C10 C10 C11 C12 C13 C14 C14 C14 C15 C15 C15
C8 C9 C5 C9 C6 C3 C4 C3 C7 C7 N1 C4 C4 C1 S1 S1 N3 S1 S1 N2 S2 S2 C15 C16 C16 C12 C11 C14 C15 S2 S2 N2 C14 C14
89.7(10) 91.4(10) 111.7(18) 113.8(16) 114.3(19) 128.1(15) 113(2) 116.0(17) 116.3(14) 127.7(18) 119(2) 122.1(17) 118.5(17) 126(2) 108.7(15) 125.2(18) 129(2) 110.5(15) 120.4(15) 124.4(18) 125.2(17) 110.4(17) 119(2) 127.2(18) 113.3(17) 127.4(18) 111(2) 125(3) 116(2) 131.3(19) 111.8(13) 127.3(16) 120.2(19) 112.5(15)
Mp 155 –156 8C (Lit. mp 155 –156 8C [9]). 3.2. The hydrobromide of 2-amino-4methylbenzothiazole 4 is prepared [9] Mp 253 –254 8C (Lit. 254 8C [9]). 3.3. The 3H-2-imino-4-methylbenzothiazoline 6 A mixture of the hydrobromide of 2-amino-4methylbenzothiazole 4 (10 g, 0.41 mol), and hydrazine hydrate 85% (0.055 mol) in 38 ml of glycol was refluxed (165 – 175 8C) while stirring for 14 h. The color of the reaction mixture changed to green, and gave a homogeneous solution. A white solid was precipitated at the end of the reflux period. The mixture was cooled and the product was filtered, washed with water, air-dried and recrystallized from ethanol to give white prism crystal of 6. It gave a 10.4 g, mp 139– 140 8C product. The purified product was dissolved in ethyl acetate: petroleum ether: ethanol solution. The crystal was obtained after 7 days by evaporation of the solvent.
Acknowledgments The authors wish to acknowledge the support to this project by NNSFC (chuangxin qunti, 2002-001), University Key Teacher by the Ministry of Education and Lanzhou University NLAOC.
References [1] A. Gvozdjakova, J. Habsudova, K. Kufcakova, Stud. Org. Chem. (Amsterdam) 35 (1988) 297 Chem. Abstr. 110 (1989) 11474n. [2] D.S. Deshpande, Acta Cienc Indica (Ser.) Chem. 6 (1980) 80 Chem. Abstr. 94 (1981) 65568b.
152
H.-S. Dong et al. / Journal of Molecular Structure 641 (2002) 147–152
[3] R.K. Acngill, N. Matsuura, F. Tabuchi, European Patent 213 814, 1987, (Chem. Abstr. 107 (1987) 178600m). [4] H.-S. Dong, J.-R. Zhang, Y.-B. Tang, X.-R. Mao, B. Quan, J. Chin. Chem. Soc. 48 (2001) 783. [5] H.-S. Dong, B. Quan, E.-F. Chai, X.-R. Mao, J. Mol. Struct. 608 (2002) 41–47.
[6] B.S. Holla, A. D’Souza, B. Kalluraya, J. Indian Chem. Soc. 68 (1991) 250. [7] A. Miyashita, I. Nagasaki, A. Kawano, Y. Suzuki, K.-I. Iwamoto, T. Higashino, Heterocycles 45 (1997) 745. [8] M. Fehlmann, Acta Cryst. B26 (1970) 1736. [9] C.E. Dalgliesh, F.G. Mann, J. Chem. Soc. (1945) 900.