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Metal complexes of 1-(2-thenyl)methyl-2-(2-thenyl)benzimidazole and of N,N′-1,2-phenylenebis(2-thenylideneimine)
Z inorg, nucl. Chem., 1975, Vol. 37, pp. 1417-I420. Pergamon Press. Printed in Great Britain
METAL COMPLEXES OF 1-(2-THENYL)METHYL-2-(2-THENYL)BENZIMIDAZOLE AND OF N,N'-I,2-PHENYLENEBIS(2-THENYLIDENEIMINE) A. FURUHASHI, T. NOMURA, T. NOZAWA and S. EDANAMI Department of Chemistry, College of Science and Engineering, Aoyama Gakuin University, t-16-1 ChitosedaL Setagaya-ku, Tokyo, Japan 157
(First received 27 July 1974: in revisedform 9 September 1974) Abstract--Some bivalent metal complexes of I-(2-thenyl)methyl-2-(2-thenyl)benzimidazole(TMYBl)of the general formula M(TMTBI)zX2 M=Co, Cu, Zn, Cd or Hg and X=C1 , Br- or I and copper complex of N,N'-1,2phenylenebis(2-thenylideneimine) (PTI), Cu(PTI)2CIO4 are prepared. M(TMTBI):X: are found to be nonelectrolytes in nitrobenzene. Magnetic susceptibilities and i.r., electronic and NMR spectra are reported.
INTRODUCTION THE compound obtained by the condensation reaction of o-phenylenediamine with 2-thiophenealdehyde is yellow needles. Ho and Livingstone[l] reported thai the compound is N,N'-l,2-phenylenebis-(2-thenylideneimine) and the imine may act as a unidentate ligand in the Co(II) complex from their experimental results; elemental analyses, magnetic property and electrical conductivity of its nitrobenzene solution. And they interpreted the fact the imine behaves as an unidentate since the coordination through two nitrogen atoms of the ligand would require gross deformation of the bond angles. On the other hand, N,N'-phenylenebis(salicylideneimine) acts as a quadridentate ligand [2] though the bond angles of C - C - N are the same as that of the N,N'-phenylenebis-(2thenylideneimine) and o-phenylenediamine which behaves as a bidentate as well as unidentate ligand[3-7]. Consequently, it is interesting thai whether the N,N'phenylenebis(2-thenylideneimine) really acts as an unidentate ligand or not as Ho and Livingstone has reported. In order to clarify the fact the authors have synthesized new metal complexes of cobalt(II), copper(ll), zinc(II), cadmium(II) and mercury(II) havingothe different ionic radii, 0.74, 0.72, 0.74, 0.97 and 1.1"0A, respectivly. The compound behaves only an unidentate ligand. From the speclral measurements it has become apparent that the compound isolated by the condensation reaction of tbiophene-2-aldehyde and o-phenylenediamine is 1 - (2 thenyl)methyl - 2 - (2 - thenyl)benzimidazole. On the other hand, the formation of the N,N' - 1,2 phenylene bis(2 - thenylideneimine) is expected as an intermidiate in this condensation reaction. Bose and Pate[[8] reported that the condensation of benzaldehyde with o-phenylenediamine gives 1-benzyl-2phenylbenzimidazole(BPl). In this reaction the Schiff base, N,N'-phenylenebis((benzitideneimine) (PBI) has been postulated as an intermediate. They found that the reaction of o-phenylenediamine in presence of copper (ll) perchlorate with benzaldehyde gives copper(I) chelate complex of PBI.
The authors have synthesized copper(I) chelate complex of the PTI using thiophene-2-aldehyde instead of benzaldebyde in the reaction reported by Bose. Magnetic and spectral measurements of the compound and the experimental results were compared with that of the complexes of the TMTBI.
EXPERIMENTAL
Physical measurements I.R. spectra in the NaC1 region were measured with a JASCO model IR-G i.r. spectrophotometer as KBr disks. The electronic spectra were obtained with Shimazu MPS-50-type automatic recording spectrophometer as nitrobenzene solutions. The magnetic moments of the complexes were measured by Gouy's method at room temperature (25°C). The NMR spectra were obtained with a Hitachi Perkin-EImer Model-R-20 NMR spectrometer.
Syntheses I - (2 - Thenyl)methyl - 2 - (2 - thenyl)benzimidazole was prepared by the method of Ho and Livingstone[l] or by reacting o-pbenylenediamine with thiophene-2-aldehyde in ethanol containing glacial acetic acid. Dichloro - bis - 1 - (2 - thenyl)methyl - 2 - (2 - thenyl)benzimidazole cobalt(II) was obtained by following procedure. A solution of hydrated cobalt chloride (5 mmol) in ethanol (20 ml) was treated with imidazole (2 g) dissolved in ethanol (20 ml). The light blue product was precipitated. The other metal complexes of the imidazole were synthesized almost by the same way the case of the Co(TMTBI)zC12. Bis - N,N' - 1,2 - phenylenebis(2 - theny[idenimine)copper(l) perchlorate was synthesized by the reaction of his - o - phenylene - diaminecopper(II)perchlorate[6] and thiophene - 2 - aldehyde in ethanol, which is according to the procedure of Bose and Patel [8]. RESULTS AND DISCUSSION
The complexes of the [ - (2 - thenyl)methyl - 2 - (2 then yl ) benzimidazole. Analytical data of the complexes are shown in Table I together with their color, magnetic data and melting points (may be decomposed at the temperature). From the magnetic moments it is assumed that the
1417
A. FURUHASHIet al.
1418
Table 1. Elemental analyses (in wt%) Compound
Color
C
L
Yellow
Co/-aC12
Blue
Co/-aBr2
Blue
Co/-aI2
Green
CuLzC12
Olive
CuL2Br2
Brown Pale yellow Pale yellow Pale yellow Pale yellow Yellow white Pale yellow Pale yellow
ZnL:C12 ZnL2Br2 ZnL212 CdL2C12 CdLzl2 HgL2Br2 HgL2I:
H
N
S
M
Calcd. Obs. Calcd.
64.86 4 . 0 5 9 . 4 6 21.62 * 64.74 4.10 9.51 21.53 * 53.18 3 . 3 2 7 . 7 6 17.73 8.t7
Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs.
52.83 47.35 46.98 42.43 42.30 52.85 52.96 47.08 46.62 52.71 52.40 46.98 46.81 42.14 42.28 49.52 49.43 40.07 40.05 40.32 39.89 36.70 36.96
3.24 2.96 3.01 2.65 2.50 3.30 3.20 2.94 2.95 3.32 3.32 2.96 2.94 2.66 2.66 3.12 3.01 2.53 2.60 2.54 2.63 2.31 2.23
7.81 6.91 6.78 6.12 6.11 7.71 7.72 6.97 7.02 7.69 7.48 6.85 6.69 6.14 6.08 7.22 7.18 5.84 5.78 5.88 5.9t 5.35 5.38
17.42 15.78 15.63 14.14 14.15 17.61 17.58 15.69 15.64 17.59 17.41 15.68 15.59 14.06 14.03 16.52 16.42 13.37 13.17 13.45 13,38 12.25 12.01
/z(B.M.) m.p * * *
* 142 *
8 . 2 9 4.39 285 7.28 * * 7.30 4.41 270 6.52 * * 6.41 4.76 280 8.74 * * 9.01 1.78 240 7.91 * * 8.17 1,87 234 8.97 * * 8.87 * 280 7.99 * * 8.04 * 288 7.17 * * 7.18 * 286 14.48 * * 14.41 * 276 11.72 * * 11.82 * 272 21.04 * * * * 195 19.15 * * * * 177
L : TMTBI. Co(II) complexes are tetrahedral form [9-12]. The copper complexes show the moment 1.8-2.2 B.M. expected for Cu(II) complexes[13, 14]. The electronic absorption spectra in the visible region of the cobalt and copper complexes are shown in Table 2. The spectra of Co(II) complexes show that of tetrahedral form[6, 15]. The wave number about 17-14.5kK are assigned the transition from the 4A2 ground state to the 4T~(P) state and absorption is very intense. The red shift of the band was recognized when the halogen ion CF was substituted by either Br- or I- and the wave numbers of the band of these three complexes decrease in the order of Cl-, Br-, I- and the fact is explained by the spectrochemi-
cal series and the molar absorbance also increase in the order following the hyperchromic effect [16-18]. The facts show that the halogeno ions coordinate to the central cobalt ion. In the case of copper complexes, the band at about 11 kK may be assigned as 2B:-~2A~ band of the copper(II) ions in the distorted tetrahedral configuration[19]. The H NMR spectra of the imidazole are shown in Table 3. The metal complexes show the almost same spectra. The spectra would fit with the structure shown in Fig. 1, 1 - (2 - thenyl)methyl - 2 - (2- thenyl)benzimidazole. The i.r. spectra of the imidazole and its metal complexes are very similar. The stretching band of C=N
Table 2. Electronic absorption spectra (figures are given in kK and e) Co(TMTBI)£12
Co(TMTBIhBr2
Co(TMTBI)212
Cu(TMTBI)£12
Cu(TMTBI):Br2
17.5(3.20 x 102) 16.3(5.57 x'10% 15.7(5.98 x 102)
16.9(3.50 x 102) 15.8(6.26 x 102) 15.2(7.20× l0s)
16.3(5.82 x 102) 15.1(7.76 x 102) 14.5(8.15 x l0s)
23.4(6.15 x 10) 20.9(1.00 x 102)
22.4(1.29 x 10% 15.3(4.35 x 10)
Table 3. NMR spectral data TMTBI and M(TMTBI)zX:
Cu(PTI)£104
8(ppm)
Integrated for
Assignment
3(ppm)
Integrated for
Assignment
6.8-7.8 5.6
10 H 2H
Phenyl and thenyl Methylene
9.2 7-7.9
2H 10 H
Azomethine Phenyl and Thenyl
Metal complexes of l-(2-thenyl)methyl-2-(2-thenyl)benzimidazoleand of N,N'-1,2-phenylenebis(2-thenylideneimine)
Fig. 1. 1 - (2 - Thenyl)methyl - 2 - (2 - thenyl)benzimidazole (TMTBI). of imidazoles is usually expected in the range 1500-1550 cm -~ and the band is lowered by 10-15 cm -~ in frequency when it is coordination by the nitrogen atom[23 26]. The sharp band in the ligand at 1475 cm ~is not recognized in the complexes. May be the band is lowered and mixed with that of the phenyl group about at 1465 cm -~. From the conductivity measurements of 10-3M nitrobenzene solution of these complexes, the complexes seem to be essentially non-electrolytes in nitrobenzene. From the experimental results described above, it is confirmed that the solid yellow needles separated out from the condenzation of o-phenylenediamine with thiophene-2-aldehyde is characterised as 1 (2 thenyl)methyl - 2 - (2 - thenyl)benzimidazole and the imidazole behaves as an unidentate ligand in its metal complexes and coordination has occurred through the unsaturated nitrogen atom as in the cases of the other benzimidazole complexes [23-26].
The copper(I) complex o f N , N ' - 1,2 - phenylenebis(2 then ylideneimine ) Analytical data of the complex are as follows (Calcd. for Cu(PTI)2CIO4: C, 50.85; H, 3.21; N, 7.41; S, 16.97; Cu, 8.41. Found: C, 50.18; H, 3.24; N, 7.45; S, 16.58; Cu, 8.24%). It is diamagnetic at room temperature. The fact shows that the copper is monovalent state in this compound [13, 14]. The electronic absorption spectra in the visible region show only one peak at 23.5 kK. The band is assumed that the charge transfer band. The H NMR spectra differ very much from the case of the TMTBI complexes. The spectra show the signal at 9.2 ppm and is assigned as the azomethine proton of PTI (Fig. 2). It would be expected to show up at about 8.3 ppm[20-22]. The other 10 H are appeared at the range 7-7.9 ppm as overwrapped signals each other. The i.r. spectra are confirmed further the complex is
Fig. 2. N,N'- 1,2- phenylenebis(2 - thenylideneimine)(PTI).
1419
different from the imidazole complex. The complex shows a sharp band at 1660 cm-'. The band is not recognized in the spectra of the complex containing ophenylenediamine and M(TMTBI)2X2. The band may be assigned to -CH=N- function of the imine [20-22]. On the other hand, the strong band at 1100 cm-' is assumed that of CIO~ . The result of the conductivity measurement shows that the complex should be uni-univalent electrolyte in nitrobenzene as the molecular conductivity is 32 mho (As,~,at 25°C)[1]. The experimental results mentioned above show that the N,N' - 1,2 - phenylenebis(2 - thenylideneimine) can act as a bidentate ligand though the isolation of the imine is not possible because of the benzimidazole ring is very stable and can be formed feasibily by the condensation reaction.
Acknowledgements--The authors would like to acknowledge the continuing guidances and encouragements of Drs. Y. Yoshino and A, Ouchi of College of the General Education, the University of Todyo. The authors also wish to express their gratitude to Drs. K. Kimura and Y. Hirao of the Aoyama Gakuin University about their useful discussions.
REFERENCES
1. R. K. Y. Ho and S, E. Livingstone, Australian J. Chem. 18, 659 (1965). 2. P. Pfeiffer, E. Breith, E. Lube and T. Tsumaki, Ann. 503, 84 (1933). 3. D. R, Marks, D. J. Phillips and J. P. Redfern, J. Chem. Sac. A 1464 (1967). 4. A. V. Butcher, D. J. Phillips and J. P. Redfern, J. Chem. Soc. A, 1064 (1968). 5. D. R. Marks, D. J. Phillips and J. R. Redfern, J. Chem. Soc. A, 2013 (1968). 6. E. J. Duff, J. Chem. Soc. A, 434, 836 (1%8). 7, E. J. Duff, J. lnorg. Nucl. Chem. 30, 861 (1968). 8. K. S. Bose and C. C. Patel, J. lnorg, Nucl. Chem. 32, 2423 (1970). 9. J. R. Bethell and P. Maitland, J. Chem. Soc. 3751 (1962), 10. F. A. Cotton and G. Wilkinson, Advanced Inorganic Chemistry, 2nd Edn, p. 873. Wiley, New York (1966). 11. B. N. Figgs and R. S. Nyholm, J. Chem. Soc. 338 (1959). 12. S. Prasad, Y. M. Reddy and M. R. Secthapathy, J. Indian Chem. Soc. 42, 46 (1%5). 13. D. Forster and D. M. L. Goodgame,J. Chem. Soc. 2790 (1%4). 14. D. Forster and D. M. L. Goodgame. lnoro. Chem. 4, 715 (1965). 15. F. A. Cotton and G. Wilkinson, Advanced Inorganic Chemistry, 2nd Edn, p. 871. Wiley, New York (1%6). 16. F. A. Cotton and G. Wilkinson, Advanced Inorganic Chemistry, 2rid Edn, p. 680. Wiley, New York (1966). 17. R. Tsuchida, Bull. Chem. Soc. Japan 13, 388,426,471 (1938). 18. M. Goodgame and F. A. Cotton, or. Am. Chem. Soc. 84, 1543 (1962). 19. D. Forster and D, M. L. Goodgame, Inorg. Chem. 4, 823 (1965). 20. J. G. Smith and 1. Ho, Tetrahedron Lett. 38, 3541 (1971). 21. V. Veeranggiah, C. V. Ratnam and N. V. S, Rao, Indian J. Chem. 6, 279 (1968). 22. M. Green and P. A. Tasker, J. Chem. Soc. A, 2531 (1970).
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23. K. S. Bose and C. C. Patel, J. Inorg. Nucl. Chem. 32, 1141 0970). 24. T. J. Lane and K. P. Quinlan, 3. Am. Chem. Soc. 82, 2994 (1960).
25. T. J. Lane, I. Nakayama, J. L. Walter and A. J. Kandathil, Inorg. Chem. 1, 267 (1962). 26. M. S. Elder, G. A. Nelson and D. H. Busch, Inorg. Chem. 5, 74 (1966).
METAL COMPLEXES OF 1-(2-THENYL)METHYL-2-(2-THENYL)BENZIMIDAZOLE AND OF N,N'-I,2-PHENYLENEBIS(2-THENYLIDENEIMINE) A. FURUHASHI, T. NOMURA, T. NOZAWA and S. EDANAMI Department of Chemistry, College of Science and Engineering, Aoyama Gakuin University, t-16-1 ChitosedaL Setagaya-ku, Tokyo, Japan 157
(First received 27 July 1974: in revisedform 9 September 1974) Abstract--Some bivalent metal complexes of I-(2-thenyl)methyl-2-(2-thenyl)benzimidazole(TMYBl)of the general formula M(TMTBI)zX2 M=Co, Cu, Zn, Cd or Hg and X=C1 , Br- or I and copper complex of N,N'-1,2phenylenebis(2-thenylideneimine) (PTI), Cu(PTI)2CIO4 are prepared. M(TMTBI):X: are found to be nonelectrolytes in nitrobenzene. Magnetic susceptibilities and i.r., electronic and NMR spectra are reported.
INTRODUCTION THE compound obtained by the condensation reaction of o-phenylenediamine with 2-thiophenealdehyde is yellow needles. Ho and Livingstone[l] reported thai the compound is N,N'-l,2-phenylenebis-(2-thenylideneimine) and the imine may act as a unidentate ligand in the Co(II) complex from their experimental results; elemental analyses, magnetic property and electrical conductivity of its nitrobenzene solution. And they interpreted the fact the imine behaves as an unidentate since the coordination through two nitrogen atoms of the ligand would require gross deformation of the bond angles. On the other hand, N,N'-phenylenebis(salicylideneimine) acts as a quadridentate ligand [2] though the bond angles of C - C - N are the same as that of the N,N'-phenylenebis-(2thenylideneimine) and o-phenylenediamine which behaves as a bidentate as well as unidentate ligand[3-7]. Consequently, it is interesting thai whether the N,N'phenylenebis(2-thenylideneimine) really acts as an unidentate ligand or not as Ho and Livingstone has reported. In order to clarify the fact the authors have synthesized new metal complexes of cobalt(II), copper(ll), zinc(II), cadmium(II) and mercury(II) havingothe different ionic radii, 0.74, 0.72, 0.74, 0.97 and 1.1"0A, respectivly. The compound behaves only an unidentate ligand. From the speclral measurements it has become apparent that the compound isolated by the condensation reaction of tbiophene-2-aldehyde and o-phenylenediamine is 1 - (2 thenyl)methyl - 2 - (2 - thenyl)benzimidazole. On the other hand, the formation of the N,N' - 1,2 phenylene bis(2 - thenylideneimine) is expected as an intermidiate in this condensation reaction. Bose and Pate[[8] reported that the condensation of benzaldehyde with o-phenylenediamine gives 1-benzyl-2phenylbenzimidazole(BPl). In this reaction the Schiff base, N,N'-phenylenebis((benzitideneimine) (PBI) has been postulated as an intermediate. They found that the reaction of o-phenylenediamine in presence of copper (ll) perchlorate with benzaldehyde gives copper(I) chelate complex of PBI.
The authors have synthesized copper(I) chelate complex of the PTI using thiophene-2-aldehyde instead of benzaldebyde in the reaction reported by Bose. Magnetic and spectral measurements of the compound and the experimental results were compared with that of the complexes of the TMTBI.
EXPERIMENTAL
Physical measurements I.R. spectra in the NaC1 region were measured with a JASCO model IR-G i.r. spectrophotometer as KBr disks. The electronic spectra were obtained with Shimazu MPS-50-type automatic recording spectrophometer as nitrobenzene solutions. The magnetic moments of the complexes were measured by Gouy's method at room temperature (25°C). The NMR spectra were obtained with a Hitachi Perkin-EImer Model-R-20 NMR spectrometer.
Syntheses I - (2 - Thenyl)methyl - 2 - (2 - thenyl)benzimidazole was prepared by the method of Ho and Livingstone[l] or by reacting o-pbenylenediamine with thiophene-2-aldehyde in ethanol containing glacial acetic acid. Dichloro - bis - 1 - (2 - thenyl)methyl - 2 - (2 - thenyl)benzimidazole cobalt(II) was obtained by following procedure. A solution of hydrated cobalt chloride (5 mmol) in ethanol (20 ml) was treated with imidazole (2 g) dissolved in ethanol (20 ml). The light blue product was precipitated. The other metal complexes of the imidazole were synthesized almost by the same way the case of the Co(TMTBI)zC12. Bis - N,N' - 1,2 - phenylenebis(2 - theny[idenimine)copper(l) perchlorate was synthesized by the reaction of his - o - phenylene - diaminecopper(II)perchlorate[6] and thiophene - 2 - aldehyde in ethanol, which is according to the procedure of Bose and Patel [8]. RESULTS AND DISCUSSION
The complexes of the [ - (2 - thenyl)methyl - 2 - (2 then yl ) benzimidazole. Analytical data of the complexes are shown in Table I together with their color, magnetic data and melting points (may be decomposed at the temperature). From the magnetic moments it is assumed that the
1417
A. FURUHASHIet al.
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Table 1. Elemental analyses (in wt%) Compound
Color
C
L
Yellow
Co/-aC12
Blue
Co/-aBr2
Blue
Co/-aI2
Green
CuLzC12
Olive
CuL2Br2
Brown Pale yellow Pale yellow Pale yellow Pale yellow Yellow white Pale yellow Pale yellow
ZnL:C12 ZnL2Br2 ZnL212 CdL2C12 CdLzl2 HgL2Br2 HgL2I:
H
N
S
M
Calcd. Obs. Calcd.
64.86 4 . 0 5 9 . 4 6 21.62 * 64.74 4.10 9.51 21.53 * 53.18 3 . 3 2 7 . 7 6 17.73 8.t7
Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs. Calcd. Obs.
52.83 47.35 46.98 42.43 42.30 52.85 52.96 47.08 46.62 52.71 52.40 46.98 46.81 42.14 42.28 49.52 49.43 40.07 40.05 40.32 39.89 36.70 36.96
3.24 2.96 3.01 2.65 2.50 3.30 3.20 2.94 2.95 3.32 3.32 2.96 2.94 2.66 2.66 3.12 3.01 2.53 2.60 2.54 2.63 2.31 2.23
7.81 6.91 6.78 6.12 6.11 7.71 7.72 6.97 7.02 7.69 7.48 6.85 6.69 6.14 6.08 7.22 7.18 5.84 5.78 5.88 5.9t 5.35 5.38
17.42 15.78 15.63 14.14 14.15 17.61 17.58 15.69 15.64 17.59 17.41 15.68 15.59 14.06 14.03 16.52 16.42 13.37 13.17 13.45 13,38 12.25 12.01
/z(B.M.) m.p * * *
* 142 *
8 . 2 9 4.39 285 7.28 * * 7.30 4.41 270 6.52 * * 6.41 4.76 280 8.74 * * 9.01 1.78 240 7.91 * * 8.17 1,87 234 8.97 * * 8.87 * 280 7.99 * * 8.04 * 288 7.17 * * 7.18 * 286 14.48 * * 14.41 * 276 11.72 * * 11.82 * 272 21.04 * * * * 195 19.15 * * * * 177
L : TMTBI. Co(II) complexes are tetrahedral form [9-12]. The copper complexes show the moment 1.8-2.2 B.M. expected for Cu(II) complexes[13, 14]. The electronic absorption spectra in the visible region of the cobalt and copper complexes are shown in Table 2. The spectra of Co(II) complexes show that of tetrahedral form[6, 15]. The wave number about 17-14.5kK are assigned the transition from the 4A2 ground state to the 4T~(P) state and absorption is very intense. The red shift of the band was recognized when the halogen ion CF was substituted by either Br- or I- and the wave numbers of the band of these three complexes decrease in the order of Cl-, Br-, I- and the fact is explained by the spectrochemi-
cal series and the molar absorbance also increase in the order following the hyperchromic effect [16-18]. The facts show that the halogeno ions coordinate to the central cobalt ion. In the case of copper complexes, the band at about 11 kK may be assigned as 2B:-~2A~ band of the copper(II) ions in the distorted tetrahedral configuration[19]. The H NMR spectra of the imidazole are shown in Table 3. The metal complexes show the almost same spectra. The spectra would fit with the structure shown in Fig. 1, 1 - (2 - thenyl)methyl - 2 - (2- thenyl)benzimidazole. The i.r. spectra of the imidazole and its metal complexes are very similar. The stretching band of C=N
Table 2. Electronic absorption spectra (figures are given in kK and e) Co(TMTBI)£12
Co(TMTBIhBr2
Co(TMTBI)212
Cu(TMTBI)£12
Cu(TMTBI):Br2
17.5(3.20 x 102) 16.3(5.57 x'10% 15.7(5.98 x 102)
16.9(3.50 x 102) 15.8(6.26 x 102) 15.2(7.20× l0s)
16.3(5.82 x 102) 15.1(7.76 x 102) 14.5(8.15 x l0s)
23.4(6.15 x 10) 20.9(1.00 x 102)
22.4(1.29 x 10% 15.3(4.35 x 10)
Table 3. NMR spectral data TMTBI and M(TMTBI)zX:
Cu(PTI)£104
8(ppm)
Integrated for
Assignment
3(ppm)
Integrated for
Assignment
6.8-7.8 5.6
10 H 2H
Phenyl and thenyl Methylene
9.2 7-7.9
2H 10 H
Azomethine Phenyl and Thenyl
Metal complexes of l-(2-thenyl)methyl-2-(2-thenyl)benzimidazoleand of N,N'-1,2-phenylenebis(2-thenylideneimine)
Fig. 1. 1 - (2 - Thenyl)methyl - 2 - (2 - thenyl)benzimidazole (TMTBI). of imidazoles is usually expected in the range 1500-1550 cm -~ and the band is lowered by 10-15 cm -~ in frequency when it is coordination by the nitrogen atom[23 26]. The sharp band in the ligand at 1475 cm ~is not recognized in the complexes. May be the band is lowered and mixed with that of the phenyl group about at 1465 cm -~. From the conductivity measurements of 10-3M nitrobenzene solution of these complexes, the complexes seem to be essentially non-electrolytes in nitrobenzene. From the experimental results described above, it is confirmed that the solid yellow needles separated out from the condenzation of o-phenylenediamine with thiophene-2-aldehyde is characterised as 1 (2 thenyl)methyl - 2 - (2 - thenyl)benzimidazole and the imidazole behaves as an unidentate ligand in its metal complexes and coordination has occurred through the unsaturated nitrogen atom as in the cases of the other benzimidazole complexes [23-26].
The copper(I) complex o f N , N ' - 1,2 - phenylenebis(2 then ylideneimine ) Analytical data of the complex are as follows (Calcd. for Cu(PTI)2CIO4: C, 50.85; H, 3.21; N, 7.41; S, 16.97; Cu, 8.41. Found: C, 50.18; H, 3.24; N, 7.45; S, 16.58; Cu, 8.24%). It is diamagnetic at room temperature. The fact shows that the copper is monovalent state in this compound [13, 14]. The electronic absorption spectra in the visible region show only one peak at 23.5 kK. The band is assumed that the charge transfer band. The H NMR spectra differ very much from the case of the TMTBI complexes. The spectra show the signal at 9.2 ppm and is assigned as the azomethine proton of PTI (Fig. 2). It would be expected to show up at about 8.3 ppm[20-22]. The other 10 H are appeared at the range 7-7.9 ppm as overwrapped signals each other. The i.r. spectra are confirmed further the complex is
Fig. 2. N,N'- 1,2- phenylenebis(2 - thenylideneimine)(PTI).
1419
different from the imidazole complex. The complex shows a sharp band at 1660 cm-'. The band is not recognized in the spectra of the complex containing ophenylenediamine and M(TMTBI)2X2. The band may be assigned to -CH=N- function of the imine [20-22]. On the other hand, the strong band at 1100 cm-' is assumed that of CIO~ . The result of the conductivity measurement shows that the complex should be uni-univalent electrolyte in nitrobenzene as the molecular conductivity is 32 mho (As,~,at 25°C)[1]. The experimental results mentioned above show that the N,N' - 1,2 - phenylenebis(2 - thenylideneimine) can act as a bidentate ligand though the isolation of the imine is not possible because of the benzimidazole ring is very stable and can be formed feasibily by the condensation reaction.
Acknowledgements--The authors would like to acknowledge the continuing guidances and encouragements of Drs. Y. Yoshino and A, Ouchi of College of the General Education, the University of Todyo. The authors also wish to express their gratitude to Drs. K. Kimura and Y. Hirao of the Aoyama Gakuin University about their useful discussions.
REFERENCES
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