Synthesis and Spectroscopic Studies of Co(Ii), Ni(Ii) and Cu(Ii) Complexes of Bidentate Schiff Base Having N and Sulphur Containing Donor Site

Introduction

Coordination compounds play a vital role in several fields Schiff base plays a central role in the field of coordination chemistry due to their biocidal activities including anticancer, antifungal, herbicidal and antibacterial. The high reactivity specificity and a number of Schiff bases in industry, medicine & agriculture are used in catalytic reaction and as biological models for understanding biomolecules. Schiff base compounds that are widely studied are attracting wide range of applications in organic synthesis and metal ion complexation^5-8. The conventional synthesis of such compounds are still very common along with modern synthetic approaches in continuation of our recent work in synthesizing Schiff bases and their transition metal complexes, we herein report, synthesis and spectroscopic studies of Co(II), Ni(II) and Cu(II) complexes with 2-methyl thioquinazoline – 4(3H) semicarbazone.

Experimental

All the chemicals and reagents used were of AnalR grade. The ligand and complexes were analysed using standard procedure¹⁶. Magnetic susceptibility was measured by using Gouy balance using Hg [ Co(NCS)₄] as a calibrant. IR spectra were recorded on Perkin Elmer – 577 spectrophotometer using KBr disc. The electronic spectra of the complexes were recorded on a cary-2390 spectrophotometer.The molar conductance values were done on systronics conductivity meter using DMF as a solvent.

Table: 1 Analytical and Physical Data of Schiff Base, Mtqs and their Metal Complexes

Compounds	Molar	Yield	Analysis %				meff	Wm ohm	D T oC	l max
	mass	%	found (calculated)				B. M.	-1 cm2 mol-1		electronic cm-1
			M	C	N	H
MTQS Brown	237	62		50.40 (50.63)	29.39 (29.53)	4.58 (4.64)
[Co(MTQS)2Cl2 ]	603.9	63	9.68	39.56	23.09	3.59	4.87	17.1	217	9622, 19270,
Brown			(9.75)	(39.73)	(23.18)	(3.64)				21700
[Co(MTQS)2Br2]	692.74	62	8.41	34.50	20.02	3.12	4.80	17.7	206	9263, 19347,
Brown	8		(8.50)	34.64)	(20.20)	(3.17)				22217
[Co(MTQS)2I2]	786.73	65	7.36	30.29	17.60	2.73	4.89	16.9	211	9336, 19510,
Brown	8		(7.49)	(30.50)	(17.79)	(2.79)				22280
[Co(MTQS)2(NO3)2]	656.93	62	8.89	36.41	21.18	3.28	4.82	16.2	214	9433, 19470,
Dark brown			(8.97)	(36.53)	(21.31)	(3.34)				21940
[Ni(MTQS)2Cl2]	603.71	60	9.63	39.58	23.04	3.59	3.20	18.2	231	10620, 18340,
Orange			(9.72)	(39.75)	(23.18)	(3.64)				25317
[Ni(MTQS)2Br2]	692.52	60	8.40	34.48	20.04	3.12	3.22	18.9	227	10540, 18260,
Yellowish orange			(8.47)	(34.65)	(20.21)	(3.17)				24736
[Ni(MTQS)2I2]	786.31	61	7.38	30.33	17.62	2.71	3.18	18.7	222	10917, 18245,
Deep orange			(7.46)	(30.51)	(17.80)	(2.79)				24930
[Ni(MTQS)2(NO3)2]	656.71	62	8.86	36.30	21.20	3.17	3.12	18.4	229	10970, 18330,
Orange			(8.94)	(36.54)	(21.31)	(3.35)				25271
[Cu(MTQS)2Cl2]	608.54	64	10.35	39.27	22.84	3.53	1.94	14.4	194	15327, 29280
Green			(10.44)	(39.43)	(23.00)	(3.61)
[Cu(MTQS)2Br2]	697.35	64	9.02	34.28	19.92	3.09	1.99	14.1	199	15270, 24360
Greenish yellow	8		(9.11)	(34.41)	(20.07)	(3.15)
[Cu(MTQS)2(NO3)2]	661.54	64	9.52	36.14	211.01	3.24	1.91	14.7	192	15380, 24440
Greenish yellow			(9.60)	(36.37)	(21.16)	(3.32)

Preparation of  the Ligand (MTQS)

Ethanolic solution of 2-methyl thioquinazoline -4 (3H) one was allowed to react with semicarbazide hydrochloride dissolved in ethanolic solution of sodium acetate. The reaction mixture was refluxed on water bath for about 4 h. The solid thiosemicarbazone started separating after a few minutes. The product was filtered out and washed with ethanol and dried in oven. The compound was crystallised from ethanol and dried in oven with 62% m.p 214+ 1⁰C.

m = medium, b = broad,   s = strong,    s b = strong and broad

The coordination through carbonyl oxygen and azomethine nitrogen atom of semicarbozone moiety are further supported by the appearance of bands in the far IR region at 547-520cm^-1 and 470-450cm^-1 assigned to ^17,20n_M=o and n_M-N^17-21 respectively. The linkage with halogen is indicated by the appearance of another band in the far infrared region 330-275cm^-1. assigned ¹⁷ to n_M-x(x=CI, Br or I).

The linkage with halogen with metal ion supported by the low molar conductance of the complexes in the range 18.9-14.1 ohm^-1 cm² mol^-1. The significant band at 1460 cm and 1340 cm^-1 with a separation of 120cm^-1  indicates mono-coordinate nature of nitrate group.²²

The electronic spectral²³ and magnetic susceptibility measurements ^24,25 proposes octahedral geometry for the complexes which is justified by other physicochemical as well as infrared spectral data.

Molar Conductance

Molar conductance measurements of the complexes of Co(II), Ni(II) and Cu(II) were found to be in the range 18.9 -14.1 ohm^-1 cm² mol^-1 in DMF which proposes their non-electrolytic nature²⁶. The molar conductance values also supported the structure assigned on the basis of physicochemical and spectroscopic measurements.

Antifungal Study

The ligand MTQS and its Co(II), Ni(II) and Cu(II) complexes have been screened for their antifungal activity against Apergillus niger and Penicillium expansum. The susceptibility of fungi towards ligand and its metal complexes was tested by disc plate method²⁷. The observed results revealed an enhancement of the antifungal activity of metal complexes with free ligands which can be explained on the basis of chelation theory.

Conclusion

Thus on the basis of elemental analysis, IR, electronic spectra, molar conductance and magnetic susceptibility measurements it may be proposed that the ligand MTQS acts in a bidentated manner and coordination is proposed through azomethine N and carbonyl oxygen of semi carbazone moiety. The remaining positions of metal ions are satisfied by negative ions such as CI^—, Br^—, I^— that proposes it to be octahedral in nature as shown in Fig-1.

Figure 1: [M(MTQS)2] X2 M = Co(II) and Ni(II); X = Cl–, Br–, I– and NO3–; M = Cu(II); X = Cl–, Br–  and NO3– . Click here to View figure

 

1.  J.A McCleverty and T.J Mayer, “Comprehensive Coordination Chemistry, II, From Biology to Nanotechnology.” Vol-9 ‘Opplication of coordination chemistry.’ Elsevier Esterdam, 2003.
2. D. Chem and A.E Martel, Inorg Chem; 26, 1026, (1987).
3. D.E hamilton, R.S. Drago and A. Zombeck, J.Am. Chem; Soc; 109, 374 (1987).
4. J. Constamagna, J. Vargas, R Lattore, A. Alvaroda, and G. Mena, Coord. Chem. Rev., 67, 119(1992)
5. S. Roland and P. Mangency, Eur. J. Org. Chem; 4, 611 (2000).
6. T.K  Karmkar, B.K. Ghosh, A. Osman, H.K. Fun, E. Riviere, t Mallah, g Aroni and S. K. Chandra, Inorg chem; 4, 2391, (2005).
7. M. Habib, T. K. Karmakar, G. Arino, H. K. Fun, S. Chantrapromma and S. K. Chandra, Inorg. Chem; 47, 4109, (2008).
8. T. K. Karmakar, G. Aroni, B.K. Ghosh, A. Osman, H. K. Fun, T. Mallah, O. Behress, X. Solans and S. K. Chandra, J. Malter, 16, 278 (2006).
9. K. Tanaka and R. Shiraishi, Green chem, 2, 272 (2000).
10. B. ARoberts and J. L. Scott, Green chem.,4,245 (2002)
11. Rai B.K Kumar H, Sharma M and Rastogi V.K., J. Indian Chem. Soc; 87: 1241 (2010)
12. Rai B.K and Singh Satyadeo, Asian J Chem; 22: 5613(2010); Rai B.K and Singh Satyadeo, Asian J Chem; 22, 5619 (2010); Rai B.K and Sharma K.K, Asian J. Chem.; 22; 5625 (2010)
13. Kishore K. R. and Rai B.K, Asian J. Chem; 22, 8055(2010); Rai B.K and Bimal Kumar, Asian J. Chem. 22, 8073 (2010); Rai B.K and Singh S, Orient J. Chem; 26, 989 (2010); Rai B.K and kumar Chandan; Orient J. Chem.; 26, 1019(2010).
14. Rai B.K and Sharma K.K, Orient J. Chem.; 26, 1437 (2010); Kumar R Kishore and B.K Rai,
15. Orient J. Chem, 26, 437 (2010); Kumar R. Kishore, Kumar Rajeev and B. K. Rai, orient J. Chem, 26, 1461(2010).
16. Rai B. K. and K. K. Sharma; orient J. Chem; 27, 143 (2011); Rai B K and Kumar Rachna; Asian J. Chem, 23, 4625 (2011); Rai B. K. Sinha Puja, Vidyarthi S N, And Singh Vineeta, Asian J. Chem; 23, 4629 (2011); Rai B. K. And Kumar Bimal, Asian J Chem; 23, 4635(2011); Rai B K, Singh V, Vidyarthi S N and Sinha Puja; Asian J. Chem; 23, 4638 (2011); Kumar Bimal, Rai B K and Ambastha Nisha; Orient J Chem 27, 1173 (2011).
17. Vogel; A.I., A Textbook of quantitative chemical Analysis, Revised by Mendham; J., Denny; R. C., Barnes; J. D. and Thomas, M., Pearson Education, 7^th Edn; London, (2008).
18. Silverstein; R.M. and Webster; F.X., Spectrometric Identification of Organic Compounds, 6^th Edn., John Wiley and Sons, 109 (2008); Kemp William, Organic Spectroscopy, Palgrave, New York, 3^rd edn. (2008).
19. Balasubramanian; K.P., Karvember; R.,  Chinnuswamy, V. and Natrajan; K., Indian J. Chem, Sect., B 44, 2450 (2005).
20. Gudasi; K.B., Patil; S. A., Vadavi; R.S.,  Shenoy; R.V. and Patil; M.S., J. Serb. Chem. Soc., 71(5), 529 (2006).
21. Mahapatra; B.B. and Saraf; S.K., J. Indian Chem. Soc., 80, 696 (2003).
22. Dash; D.C., Behera; R.K., Sen; (Ms.) M. and Meher; F.M., J. Indian Chem., Soc., 71, 693 (1994).
23. Hathaway; B.J. and Underhill; A.E., J. Chem. Soc. 3091 (1961).
24. Lever, A. B. P., Inorganic Spectroscopy, Elsevier, New York (1960).
25. Carlin, R. L. and Van Dryneveledt, A. J., Magnetic properties of transition metal compounds, Springer-Verlag, New York, (1997).
26. Figgis, B.N., Introduction to ligand Field, Wiley Eastern Ltd., New Delhi, 279 (1976).
27. Chandra and Kumar U., Spectrochim Acta, 61A, 219 (2005).
28. Baur A. W., Kirby W.M., Sherris J. C. and Turk M., Am. J. Clin Pathol, 45, 493 (1966)
29. Prashar R. K. and Sharma R. C., J. Inorg. Biochem., 28, 225 (1987). 

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