Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 2(1), 45-49, Jan. (2012) Res.J.Chem.Sci. International Science Congress Association 45 Mixed Ligand Cobalt (III) Complexes with 1-Amidino-O-Methylurea and Amino Acids Mrinalini L. and A.K. Manihar Singh* Department of Chemistry, Manipur University, Canchipur, 795003, Imphal, INDIA Available online at: www.isca.in (Received 24th October 2011, revised 24th November 2011, accepted 9th December 2011)Abstract Reactions of 1-amidino-O-methylurea with cobaltous chloride in presence of water and liquor ammonia resulted in the formation of diammine bis(1-amidino-O-methylurea) cobalt(III) chloride. The present work describes the result of our investigations on the synthesis and characterization of mixed ligand complexes of 1-amidino-O-methylurea with some amino acids. Reactions of [Co(NH(AMU)]Cl.2.5HO with amino acids viz. L-valine, DL-alanine and glycyl-glycine in equimolar ratio, in water, resulted in the formation of [Co(val)(AMUH)]Cl.2HO, [Co(ala)(AMUH)]Cl.2.5HO and [Co(gly-gly)(AMUH)]Cl.HO respectively. These complexes have been characterized by elemental analysis and molar conductance values. Octahedral structure has been proposed on the basis of IR , magnetic moment and electronic spectra of the complexes. Keywords: Mixed ligand complexes,1-amidino-O-methylurea, L-valine, DL-alanine, glycyl-glycine. Introduction Besides the obvious interest in the synthesis, mixed ligand complexes are expected to provide valuable information on magnetic properties, electronic spectra, flexidentate behavior of polydentate ligands, spectrochemical equilibrium etc. The ligand 1-amidino-O-methylurea serve as a bidentate ligand satisfying both the primary and secondary valencies with the formation of inner metallic complexes. Amino acids, on the other hand, are well known chelating agents with multifunctional groups and are biologically active, creating considerable interest in their metal complexes2,3,4. Because cobalt(III) is consistently hexacoordinate in its complexes, the synthesis and elucidation of the structure through elemental analysis, conductance measurements, spectral analysis and magnetic moment measurements etc. have been undertaken. Material and MethodsThe ligand 1-amidino-O-methylurea (AMUH) and the intermediate compound diammine bis(1-amidino-O-methylurea) cobalt(III)monochloride were prepared by published procedure5,6. All chemicals used were of analytical grade. Elemental analyses were carried out on Elementar Vario El III Carlo Erba 1108 at Regional Sophisticated Instrumentation Centre, CDRI, Lucknow and the conductance was measured with EUTECH CON510 at 25C in water. The infrared spectra were run on potassium bromide phase from 400-4000 cm-1 range, with a Shimadzu FTIR 8400 S at Chemistry Department, Manipur University. Solution spectra for the compound were recorded with a Shimadzu uv-visible spectrophotometer UV-2450 at Chemistry Department, Manipur University. Preparation of Bis(1-amidino-O-methylurea) L-valinato cobalt(III) chloride: Diammine bis (1-amidino-O-methylurea) cobalt(III) chloride (1g) and L-valine (0.2918g) were dissolved in 15 ml of distilled water. The mixture was heated on a water bath until evolution of ammonia ceases. After completion of the evolution of ammonia, the dark red solution was concentrated and neutralized with HCl (2N). Cooling followed by addition of acetone to this solution produced an oily layer, from which rose red crystals of bis(1-amidino-O-methylurea)L- valinato cobalt(III)chloride crystallized out. The crystals were removed by adding acetone, followed by scratching. This complex was recrystallized from a minimum volume of hot double distilled water and again treated with acetone and scratched to obtain the pure product which was filtered and dried in a desiccator. Similarly, the complexes bis(1-amidino-O-methylurea)DL-alaninato cobalt(III) chloride and bis(1-amidino-O-methylurea) glycyl-glycinato cobalt(III) chloride were prepared by following the above procedure by taking DL-alanine or glycyl-glycine in place of L-valine. Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 45-49, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 46 Table-1 Characterization table of the complexes: found/(calculated)%Complex State/Colour Co C H N Anion H 2 O [Co(L-val)(AMUH)]Cl.2HO Crystal/Rose red 11.30 (11.40) 25.40 (25.60) 5.60 (5.20) 24.36 (24.46) 13.06 (13.7) 6.40 (6.90) [Co(DL-ala)(AMUH)]Cl.2.5HO Crystal/Rose red 11.70 (11.9) 21.84 (21.80) 5.00 (4.60) 25.80 (25.40) 13.80 (14.30) 8.80 (9.00) [Co(gly-gly)(AMUH)]Cl.HO Crystal/ Rose red 11.30 (11.50) 23.00 (23.40) 5.20 (4.60) 27.10 (27.34) 13.30 (13.80) 3.60 (3.50) Table-2 Molar Conductance data and Electronic Spectra of Cobalt (III) complexes Complex ,ohm - 1 cm 2 mol - 1 0.001M at 25C max(nm) Assignments [Co(L-val)(AMUH) 2 ]Cl 2 .2H 2 O 251 501,362,294 1 A 1g  1 T 1g , 1 A 1g  1 T 2g , LMCT [Co(DL-ala)(AMUH) 2 ]Cl 2 .2.5H 2 O 248 499,360,284 1 A 1g  1 T 1g , 1 A 1g  1 T 2g , LMCT [Co(gly-gly)(AMUH) 2 ]Cl 2 .H 2 O 242 501,355,284 1 A 1g  1 T 1g , 1 A 1g  1 T 2g , LMCT Table-3 IR frequencies (cm-1) of Cobalt (III) complexes Compounds N H C=N C O C as COO -  s COO - Co N Co O H 2 O [Co(NH 3 ) 2 (AMU) 2 ]Cl.2.5H 2 O 3290 1624 1236 - - 482 - 3348 [Co(L-val)(AMUH) 2 ]Cl 2 .2H 2 O 3250 1637 1232 1606 1359 497 619 3661 [Co(DL-ala)(AMUH) 2 ]Cl 2 .2.5H 2 O 3240 1629 1230 1604 1361 480 621 3450 [Co(gly-gly)(AMUH) 2 ]Cl 2 .H 2 O 3275 1614 1222 1606 1379 486 615 3460 Where, L-val=L-Valine, DL-ala=DL-Alanine and gly-gly=Glycyl glycine and AMUH=1-Amidino-O-methylurea. Results and DiscussionAll the complexes were coloured, highly soluble in water, stable and non-hygroscopic. Based on the analytical and conductivity data the formulae of the complexes are listed in the table 1. Conductivity and magnetic moment: The molar conductance values of the newly synthesized mixed ligand complexes registered 230-270 ohm-1 cm2 mole-1 at 0.001M in water at 25C, indicating that the complexes are uni-bivalent electrolytes 6,7 (table 2). The newly synthesized mixed ligand complexes were diamagnetic indicating a low spin octahedral geometry. IR spectra: The IR spectra (table 3) of the intermediate compound [Co(NH(AMU)]Cl.2.5HO and the newly synthesized mixed ligand complexes, Fig.1,2 and 3, exhibits significant bands at around 3240-3290 cm-1, 1614-1637 cm-1and 1222-1236 cm-1 which may be assigned to (N H)8,9,10, (C=N)10-16 and (C O C)11,17,18 stretching vibrations respectively. On comparision with the intermediate compound, the newly synthesized mixed ligand cobalt(III) complexes show appearance of new bands in the region 1604-1606 cm-1 which may be assigned to the asymmetric vibration of coordinated carboxylate groups [as(COO)] and the bands in the region1359-1397 cm-1 may be attributed to the symmetric vibration of [as(COO)] carboxylate group s(COO)]8,12,15,19. The large differences between the frequencies of [as(COO)] and [(COO)], [200cm-1] in all the complexes are indicative of the involvement of the coordination of the carboxylate groups to the metal ion in a monodentate fashion15,19,20. Other low intensity bands observed in the region, 480-497 cm-1 are assigned to (Co N)8,21,22 stretching vibrations, indicating the coordination of the nitrogen atom of the amino acids to cobalt(III) ion. The presence of lattice water 8,19,23 molecules are indicated by the broad band at the range of 3348-3460 cm-1. Thus, the overall IR spectra indicate that the ligand 1-amidino-O-methylurea (AMUH) coordinate to the metal ion as a neutral bidentate ligand and the amino acids act as monobasic bidentate ligand in all the newly synthesized complexes. Electronic spectra: The electronic spectra of the newly synthesized mixed ligand cobalt(III) complexes [Co(L-val)(AMUH)] Cl.2HO, [Co(DL-ala)(AMUH)]Cl.2.5HO and [Co(gly-gly)(AMUH)]Cl.HO are consistent with the octahedral structures assigned, showing three absorption bands in the range of = 499-501nm, 355-362 nm and = 284-297nm (Table 2) which are attributed to 1g2g ,1g1g and LMCT transitions respectively. These transitions are comparable to six coordinated cobalt(III) complexes13,24. The diamagnetic nature of the complexes also suggested an inner octahedral stereochemistry25,26,27. Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 45-49, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 47 ConclusionIt has been observed that the reaction of diammine bis (1-amidino- O-methylurea) cobalt(III) chloride with amino acids resulted in the formation of mixed ligand complexes of type [Co(L)(AMUH)]Cl2 where, L = amino acids (L- valine or DL- alanine or glycyl-glycine). All the ligands are coordinated as bidentate ligands and an octahedral geometry was observed in all the complexes. AcknowledgementsThe authors would like to acknowledge the Regional Sophisticated Instrumentation Centre, CDRI, Lucknow for providing the necessary analytical data. References 1. Dutta R.L. and Bhattacharya Anjana, Nickel(II) Mixed Chelates, J. Indian Chem. Soc , LIV, 239-253 1977) 2. Liwang Jiwen Cai, Zon-Wang Mao, Xiao-Long Feng and Jim- Wang Huang, Dinickel complexes bridge by unusual(N,O,O’)-coordinated -amino acids: Syntheses, structural characterization and magnetic properties, Trans. Met. Chem., 29, 418 (2004) 3. Sarma K.G. and Sarma Raman, Spectroscopic Study of the Interaction of Amino Acids with Copper(II) Ions in Aqueous Solution, Asian J. of Chemistry,20, 2632 (2008). 4. Weissbluth M., Haemoglobin, Springer-Verlag, New York, (1974); Ottway J.H. and Apps D.K., Biochemistry ELBS, London (1984) 5. Dutta R.L. and Ray P., Guanylureas and their metallic complexes. Part I. Synthesis of guanylalkylureas, J. Indian Chem. Soc., 36, 7 (1959) 6. Dutta R.L. and Syamal A., Donor properties of 1-amidino-O-alkylureas. Part IX. Diammine bis (1-amidino-O-alkylurea) cobalt (III) complexes, J. Indian Chem. Soc., 45, 115, (1968) 7. Jones M.M., Elementary Coordination Chemistry, Prentice-Hall, Englewood cliffs, New Jersey (1964) 8. Nakamoto K., Infrared and Raman Spectra of Inorganic and Coordination Compounds, John Wiely and Sons, New York (4th Edition) (1986)9. Dutta R.L. and Syamal A., Infrared structural studies on 1-Amidino-O-alkylureas, J. Indian Chem. Soc., 44, 569 (1967) 10. Barnard P.F.B., Metal-promoted reactions of 2-cyanopyridine: Iron(II), Cobalt(II), Nickel(II) and Copper(II) complexes of o-methylpyridine-2-carboximidate, J. Chem. Soc. A, 2140, (1969) 11. Jamnicky, Segl’a and Koman M., Methanolysis of pyridine-2-carboximidate in the coordination sphere of Copper(II), Cobalt(II), and Nickel(II). The structure of [Ni(o-methylpyridine-2-carboximidate)]Br.4HO, Polyhedron, 14, 13-14 1844) 12. Patnaik P., Dean’s Analytical ChemistryHand Book, Mc Graw Hill (2nd Edition), 7.31-7.64 (2004) 13. Chew Hee Ng., Han Kiat Alan Ong, Koh Sing Ngai, Wee Tee Tan, Lai Peng Lim, Siang Guan Teoh, Thiam Seong Chong, mer-Trans(alaninato)cobalt(III): Crystal structure, solution properties and its DNA cleavage in the presence of ascorbic acid, Polyhedron, 24, 1503-1509 (2005) 14. Yoshima Y., Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato) cobalt(III), Bull. Chem. Soc. Jpn, 75, 741 (2002) 15. Feng Guo, Ligand Derived from Glycine and O-Vanilin, Asian Journal of Chemistry, 20), 2962-2968 (2008) 16. Dyer J.R., Application of Absorption Spectroscopy of Organic Compounds, Prentice Hall, Inc., 38 (1965) 17. Dutta R.L. and Ak. Manihar Singh., Addition of Alcohols to Phenyldicyandiamides, J. Inorg. Nucl. Chem., 40, 417 (1978) 18. Mishra A.P., Physicochemical and Antimicrobial Studies On Nickel(II) and Copper(II) Schiff base complexes derived from 2-furfuraldehyde, J.Indian Chem. Soc., 76, 35-37 (1999) 19. Chang Tong Yang, Muthalgu Vetrichelvan, Xiandong Yang, Boujimaa, Moubaraki, Keith S. Murray and Jagadese J. Vittal, Synthesis, structural properties and catecholase activity of copper(II)complexes with reduced Schiff base N-(2-hydroxybenzyl)-amino acids, Dalton Trans., 113-121 (2004) 20. Ak. Manihar Singh and M. Phalguni Singh., Mixed Ligand complexes of Copper(II) with Pyridine-2-Carboxamide and Amino acids, J. Indian Council of Chemist, 26, 106, (2009) 21. Reddy P. Rabindra, Radhika M. and Manjula P., Synthesis and characterization of mixed ligand complexes of Zn(II) and Co(II) with amino acids: Relevance to zinc binding sites in zinc fingers. J. Chem. Sci., 117(3), 242 (2005) 22. Chaudhary Rakhi and Shelly, Synthesis, Spectral and Pharmacological Study of Cu(II), Ni(II) and Co(II) Coordination Complexes, Res. J. Chem. Sci., 1(5), 1-5, (2011) 23. Saleem H.S., Ramdadan A.A.T., Taha A. and Samy F., Unreported Coordination Behaviour of A Squaric Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 45-49, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 48 Bis(Hydrazone) Ligand, Res. J.Chem. Sci.,1(4), 109-116, July (2011)24. Kothari M. Vipin and Daryle H. Busch, Cobalt(III) Complexes of Cysteine and Cysteine Derivatives, Inorg. Chem., (11), 2276-2280 (1969) 25. Maria-Lalia-Kantouri, Christos D. Papadopolous, Miguel Quiros, Antonios G. Hatzidimitriou, Synthesis and characterization of new Co(III) mixed-ligand complexes, containing 2-hydroxy-aryloximes and diimines. Crystal and molecular structure of [Co(saox)(bipy)]Br, Polyhedron26, 1292-1302 2007) 26. Ki-Young Choi, Hee-Kune Lee, Haiil Ryu, Synthesis and properties of cobalt(III) complexes of 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane, Polyhedron, 26, 1693-1698 (2007) 27. Shalini Namrata Tripathi and Sharma Vinod Kumar,Synthesis, Characterization And Biological Aspects Of Iron(III),And Cobalt(III) Complexes With Some Shiff Bases Derived From Substituted Mercaptotriazole, Rev. Roum. Chim., 56(3), 189-196 (2011)Figure-1 Infrared Spectra of [Co(L-val)(AMUH)]Cl.2HO Figure-2 Infrared Spectra of [Co(DL-ala)(AMUH)(AMUH)]Cl.2.5HO Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 45-49, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 49 Figure-3 Infrared Spectra of [Co(gly-gly)(AMUH]Cl.HO Figure-4 Overlay spectra of [Co(L-val)(AMUH)]Cl2.2HO, [Co(DL-ala)(AMUH)(AMUH)]Cl.2.5HO and [Co(gly-gly)(AMUH)]Cl.HO, showing three absorption bands