Complexes of the type ML/sub2/X/sub2/ and ML/sub4/X/sub2/ (where M=Cu(II),Ni(II), Co(II), Mn(II), Zin(II), Hg(II) and Cd(II); L=6-methyl-2-aminobenzothiazole;X=-I, -NCS and -OAC have been isolated and characterised on the basis of analytical, magnetic moment, molar conductance, electronic and i.r.spectal data. The antifungal screening of Cu(II) and Hg(II) complexes is also reported

Chaurasia, M. R.

Shukla, Prema

Singh, N. K.

English

Defence Science Journal

Def Sci J, Vol 32, No 2, April 1982, pp 75-79 Transition Metal Complexes of 6-Methyl-2-Amino Benzothiazole-Part 111 M. R. CHAURASIA & (MISS) PREMA SHUKLA Department of Chemistry. D.A.V. (P-G) College, Dehradun-248 001 N. K. SINGH Department of Chemistry, Banaras Hindu University, Varanasi-221 005 Received 10 September 1980; revised 21 April 1981 Abstract. Complexes of the type ML,X, and ML,X2 (where M = Cu(II), Ni(II), Co(lI), Mn(II), Zn(II), Hg(l1) and Cd(1I); L=6-methyl-2-aminobenzothiazole; X=-I, -NCS and -OAC\ have been isolated and characterised on the basis of analytical, magnetic moment, molar conductance, electronic and i.r. spectral data. The antifungal screening of Cu(I1) and Hg(I1) complexes is also reported. 1. Introduction A survey of literature reveals that substituted benzothiazoles have analyticall-"nd biologicals5 importance. It was, therefore. thought worthwhile to investigate the metal complexes of 6-methly-2-aminobenzothiazole. The activities of many enzymes depend upon the interaction of thiozole group with a transition metal ion6. It was, therefore, interesting to know the coordinating behaviour of the ligand containing these groups. It had been found'that the substituents in 2, 4, 5 and 6 positions modify the stoichiometries and stereochemistries of the com- plexes formed6. The i.r. data show that the coordination in ihese complexes is through NH2 of the thiozole group. The Cu(1I) and Hg(I1) complexes ware screened for antifungal activity on Asper- gillus niger, Alternaria alternata, Curvularia plunata and Prnicillium fumculorus by the Potato dextrose agar method at two dilutions. 2. Experimental All the chemicals used in this study were of BDH make. 6-Methyl-2-aminobenzothia- zole was prepared by the method of Hugershoff7. M R Chaurasia et al. Preparation of ML2X2 and ML4X, type of complexes The above referred complexes were prepared by mixing together hot ethanolic solution of metal iodide, thiocyanate, acetate and 6-methyl-2-aminobe~azothiazole in 1:2 and 1 : 4 (metal : ligand) molar ratio except cadmium and mercury complexes which were prepared by mixing the solution in acetone of cadmium or mercuric iodide and the ligand. The reaction mixtures were refluxed for 3 to 4 hours. The solutions were evaporated to dryness. The resulting coloured solids were washed with distilled water and 10 per cent alcohol and dried in vacuo over anhydrous calcium chloride. Physical Measurements Molar conductance of the complexes in methanol, chloroform and acetone (M/100P) was measured in WTW conductivity meter. Magnetic susceptibility measurements were carried out at  room temperature on Cahn-Faraday (model-7550) electrobalance using Hg[Co(NCS),] as caiibrant. Diamagnetic corrections were applied by a method outlined by Figgis and Lewiss. The values of electromagnetic moments and molar conductance of the complexes are included in Table 1. Table 1. Analytical Data and General Behaviour of the Complexes M.P. ("C) Analysis Molar y,f, Stereo- conduc- (B.M.) chemis- M. N. S. tance at try Found Calcd. Found Calcd. Found Calcd. 10-'M ( ~ c m ' )  1.84 dia. 4.40 1.92 Oh 3.20 ,, 4:70 ,, 4.58 .. 6.10 ,, dia. Electronic spectra were recorded on Cary-14 and VSU-2Ph spectrophotometers. The i.r spectra were obtained in the 4000-200 cm-1 range in KBr and Nujol Mulls on Perkin-Elmer spectrophotometer (model-621 and 720). The spectral data are given in Table 2. Metal Complexes of 6-Methyl-2-Amino Benzorhiazole Table 2 Ligand Field Parameters of the Complexes Complexes 1 ODq B' p l3 ' \Z/VI 1' C3d LFSE (cm-l) (cm-l) ( %) (cm-I) (cq-l) (K .J./ mole 3. Results and Discussion The complexes are soluble in methanol, dioxan and acetone. The low molar conducti- vities of 10-3M solutions demonstrate that the domplexes are non-electrolytese. Magnetic Moments The magnetic moments (Table 1) are all normal and indiczte that CuL212 and NiL212 are square planar. The magnetic moments of CoL,l2 and CoL,(NCS), (4.44 and 4.40 B.M.) in the range 4.4 to 4.8 B.M., normally observed for the tetrahedral Co(11) com- plexes1° confirm tetrahedral geometries. The complexes of Cu(II), Ni(II), Co(II), Zn(II), CdtII) and Hg(I1) in 1 : 4 molar ratio show octahedral geometry. The diamagnetic ZnL21, and CdL,12 show sp3 type of hybridization. Electronic Spectra Ni(l1) complexes : The intraligand bands occur in the Nujol spectra of NiL212 and NiL,I, in the regions 19942-46163 cm-' and 15342-266 1 1 cm-' respectively. The spectrum of NiL,12 assumes D,h symmetryll. The bands can .be assigned to the transitions 15949 1 A,, + IA,~(V,), 19942 I A,, -+ 1 E,(v,), 23469 I A,, -+ 1 B,~(v,). The electronic spectrum of NiL412 is in accordance with tlie octahedral Ni(I1) environment'* with the ligand field; v, = 82 1 1, v2= 15342, v, = 2661 1 cm-' which can be assigned to ~ A , ~ ( F ) ,  + 3TZr',F), ~T,#:F), 3 ~ , g [ P )  transitions. Co(II) Complexes : CoL,12 and COL,(NCS)~ may be proposed to have tetrahedral str~ctures'~ as the electronic spec:ra of the complexes resemble those of Co(2-amino- thiazole)J, and Cu(2-bromo thia~ole)~CI,. The complexes show absorptions at 15523, 15610 cm-l(v,) and 5343, 5410~m-~(v,) attributed to the transitions 4,4, - 3 4 ~ ~  (F), 4r,(P) and are characteristics of Co(I1) ion in the tetrahedral environment having C,V symmetry. Using the values of v2 and v,, I ODq and B' were calculated by the equation for Co(I1) TJ. given by DragoI4. Two bands, observed at 7946 and 20000 cm-I in CoL,12 and 78 M R Chaurasia et al. at 8002 and 21052 cm-l in CoL,(OAC),, are typical of Co(I1) complexes in octahedral16 environment and may be assigned to the transitions ~ T , ~ ( F )  *4r2g (F)(vd and 4Tlg (P) (v,) respectively. Cu(I1) complexes: CuL212 yields one broad band at 17123 cm-l which is supposed to be a composite envelope of three transitions16 2~ , ,  -t 24 ,,, b Z g ,  2~ ,,. 14451 cm-I band in the spectrum of CuL4b may be due to ~ T ~ J  2 ~ ~ ~ t r a n s i t i o n l ~ .  The ratio vCu/vNi comes out to be 1.76 indicating considerable distortionw in the octahedral geometry of the complexes. . The electronic spectra of Mn(I1) complexes in Nujol do not show any d-d transition bands in the visible region. Using the above assignments, the values of IODq, Racah Parameter (B'), Nephelauxe- tic ratio (p), percentage lowering of the energy of 3p state in the complexes compared to the energy of 3p in the free gaseous ion(pO), ligand field stabilization energy (LFSE), spin-orbit coupling constant(hl) and spin-orbit coupling constant per electron (1;3d) have also been calculated by the method of Leverx8. The i.r spectrum of the ligand shows vas(NH), VS(NH)~', v(C = N), 6(NH), pr(NH2), pw(NH2) and v(C - S - C) at 3425, 3315,1550, 1650,1120, 760 and 815cm-I respectively20. The complexes show considerable change in vas(NH), (3300-3410-cm-I), vs(lYH) (3200-3310 cm-I), 6NH (161 5-1640 cm-I) pr(NHz) (1 100- 1 1 1 5 cm-l) and pw(NH& (7 15-725 cm-I) indicating the coordination through NH, group. The v(C-S-C) and VC = N remain unchanged showing the absence of coordination through cyclic sulpher and C = N groups. . Using i.r. spectra of the metal complexes containing coordinated thiocyanate groups, certain correlations between vCN and vCS modes and the type of thiocyanate bonding, have been maden-". For M-NCS bonding, v CN and v CS appear to fall in the range 2080-2010 cm-I and 860-780 cm-I respectively. The corresponding ranges for M-SCN bonding are 2120-2080 cm-I and 720-680 cm-l. For bridging thiocyanate groups M-SCN-M, vCN fall in a broader and generally in higher range than M-NCS while vCS usually occurs at intermediate frequencies. In the ionic thiocyanate, vCN occurs at 1963 cm-1 and vCS at 963 cm-l. Moreover, the mode of thiocyanate bonding may also be characterised by examining the doubly degenerate GNCS frequencyz4. In the i.r. spectrum of CoL,(NCS),, the vCN occurs at 2075 cm-l indicative of M - NCS bondingza. CoL,(OAC), shows additional bands at 1570 and 1395 cm-l which are assignable to  vas (c<:) and vs ( c<:) vibrations". The CuL,12, CuL,12, HgL212 and HgL,I, were screened for anti fungal activity on Aspergillus niger, Allernaria alternata, Curvularia plunafa and Penicillium fumculorus by employing Potato dextrose agar method at two dilutions (1 :2143 and 1:5000). The results indicate that the activity of Cu(I1) and Hg(I1) complexes against Alternaria alternata is of very high order (100 %) whereas that of Aspergillus niger is only 91 per cent. CuL412 inhibits 100 per cent spore germination of Penicilliunz fumcu- lorus and 85 per cent of Culvularia Plunta. Metal Complexes of 6-Methyl-2-Amino Benzothiozole Acknowledgements Thanks are due to Dr. M. S. Rathi, Wadia Institute of Himalayan Geology, Dehradun for his valuable help. One ofus (P. S.) is thankful to the C. S. I. R. New Delhi for the award of Junior Research Fellowhip. - .  References 1. Kawa, K. Y. & Shinra, K., J. Chem. Soc., 75 (1954). 2. Tyozo Uno, Terada, K. & Bunseki Kagaku., Akihama Sumiyaki, 10 (1961), 11 17. 3. Edelson, E. & Haskim, A. H., Dermatol and Syphilal, 66 (1952), 244. 4. Rabit, H. G., J. Am. Med. Assoc., 148 (1952), 1005. 5. Christison. I, B. et al. "Therapy of Fungus Diseases" (Little Brown & Co. Boston, Mass), 1955, p. 268. 6. Campbell, M. J. M. & Card, D. W , J. Chem. Soc. (A) (1970), 672. 7. Hughershoff, A., Ber., 36 (1903), 3134. 8. Figgis, B. N. & Lewis, J., "In Modern Coordination Chemistry" (Ed. J. Lewis and R. G. Wilkings, Interscience, N. Y.), (1960), 403. 9 Geary, W. J., Coord. Chem. Rev., (1964), 31 19. 10. Duff, E. J., Hughes, M. N., & Rutt, K. J., J. Chem. Soc., (A) (1968), 2499. 11. Goodgame, M. L. & Goodgame, M., J. Chem.Soc., (1963), 207. 12. Lever, A. P. B., "Inorganic Electronic Spectroscopy" (Elsevier, Amsterdam), 1968. 13' Duff, E. J., Hughes, M. N. & Rutt, K. J., J. Znorg. Chim. Acta, 6 (1972), 408. 14. Drago, R. S., "Physical Methods in Inorganic Chemistry" (An East-West Edition) p, 411. 15. Mathews, R. W. & Walton, R. A., lnorg Chem., 10 (1971), 1433. 16. Sacconi, L. & Ciampolini, M., J. Chem. Soc., (1964), 276. 17. Agrawal, R. C. & Rao, T. R., Transition Metal Chemistry, 2 (19771, 21. 18. Lever, A. P. B., J. Chem. Educ., 45 (1968),711. 19. khuja, I. S. and Singh, R., J. Znorg. Nucl. Chem. 35 (1973), 302. 20. Mishra, R. P., Mahapatra, B. B. & Guru, S., J. Indian. Chem. Soc., 56 (1979), 832. 21. Burmeister, J. L., Co-ord. Chem. Rev., 1 (1966), 205; 3 (1968), 225. 22. Nakamoto, K., "Infrared Spectra of Inorganic and Coordination Compounds" (John Wiley, N. Y.), 1970. 23. Ahuja, I. S. and Garg, A., J. Inorg Nucl. Chem., 34 (1972), 1929. 24. Mishra, B. & Rao, D. V., J. Inrlinn Chem. Soc., 51 (1979), 439. 

Transition Metal Complexes of 6-Methyl-2-Amino Benzothiazole -Part III

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Transition Metal Complexes of 6-Methyl-2-Amino Benzothiazole -Part III

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