Spectroscopic methods (IR, EPR and Electronic) for characterization of Homobinuclear 3D complexes

 

Nidhi Gupta

Department of Basic and Applied Sciences, Punjabi University, Patiala

*Corresponding Author E-mail: drnaveenabs@gmail.com

Tetra azadithio macrocyclic ligand has been used for the synthesis of macrocyclic complexes with copper metal salts. The stereochemistry, coordination behavior and structural analysis have been done by means of various physicochemical techniques i.e. elemental analysis, magnetic moment, molar conductance measurements and spectral studies such as IR, EPR and Electronic in DMSO/DMF solutions. The structures of the complexes have been determined with the help of spectroscopic as well as conductivity values and found to be six coordinated distorted octahedral geometry for the complexes. Molar conductance measurement revealed that the reported macrocyclic complexes were ionic and electrolytic in nature i.e. behaves as electrolyte.

 

 

 

INTRODUCTION:

Transtion metal complexes including macrocyclic ligands form coordination complexes extends from the large number of life composing and naturally occurring complexes with enormous biological functions to vast number of synthetically made for diverse biological and non biological functions. These complexes have been explored for their antibacterial, fungicidial, antitumor, anticonvulsant and catalytic activities [1-5]. The polyazamacrocyclic ligands in their complexes shows thermodynamic and kinetic inertness and have significant industrial applications, it has been created an interest to synthesize new macrocyclic complexes which may represent a novel class of metal –based antimicrobial agents and can provide opportunities for a large number of synthetic variations for the modulation of the activities[6,8].

 

The present paper describes the synthesis of the homobinuclear copper metal complexes using thiodiglycolic acid and 2, 6 diammino pyridine /2,6 diammino phenylene and their characterization by using the spectroscopic studies.

 

EXPERIMENTAL SECTION:

Physical and analytical measurements:

All the chemicals used were of A. R. Grade and all the solvents used were of high purity and distilled in laboratory before use according to the standard procedures.  All the complexes were synthesized by one pot template synthesis in order to produce high yield without side reaction due to polymerization. The C and H analysed on the carlo- Erba 1106 elemental analyzer. Kjeldahl method was used to determine the nitrogen content in the ligand and the complexes. ELICO (CM82T) conductivity bridge was used to measure the molar conductance and Sherwood scientific magnetic susceptibility Guoy balance (model no. MK1) at room temperature is used to determine the magnetic susceptibility of the complexes. Shimadzu UV-1601 spectrophotometer is used to record the electronic spectra of the complexes in the range of 200-1100nm. FT-IR spectrum BX-II spectrophotometer was used to record the ir spectra of the complexes as KBr pellets in the region 4000-200cm^-1. The X band EPR spectra of the complexes were recorded at 77K (LNT) by using the frozen DMSO glass as the matrix on E4-EPR spectrometer using DPPH as the g marker.

 

Procedure for the synthesis of the complexes:

A template method was adopted to prepare the complexes. A hot ethanolic solution of divalent metal salt was mixed with the hot ethanolic solution of 2,6 diamminopyridine/ 2,6 diamminophenylene in the molar ratio of 2:1. To this solution the hot ethanolic solution of thiodiglycolic acid in the molar ratio of one was mixed and the resultant solution was refluxed of 6-9 hrs. The colored complexes were precipitated out on cooling the solution. They were collected by filtration, washing and recrystallized with ethanol and dried over anhydrous calcium chloride. The purity of the complexes were checked by TLC.

 

RESULT AND DISCUSSION:

The general composition of the complexes was found to be M₂LX₂ (where M=Cu (II) and X= Cl^-1, NO^-3,NCS^-1). All the complexes have C, H and N composition in good agreement with those of the calculated [table1]. Molar conductance values of the complexes show the electrolytic nature of the complexes [table 1]. The copper complexes reported shows the magnetic moment values in the range of 1.92-1.99 B. M [table 2] corresponds to one electron that falls within the range normally observed for six coordinated octahedral nature of the complexes. The absence of band in the ir spectra of the complexes in the range of 3400cm^-1 confirmed the condensation of the amino to thiodiglycolic acid group. The appearance of band at 450-480cm^-1 in the spectra indicate the metal was bonded to the azomethine nitrogen. The ir spectra showed a strong band at 1609-1696cm^-1 assigned to (CO) stretching frequency[table 4]. The presence of bands at 2050-2080cm^-1 indicates that both thiocyanate groups were N-bonded [7]. The electronic spectra of the complexes shows transitions: ²B₁g  ͢  ²B₂g, ²B₁g ͢  ²Eg,  ²B₁g ͢   ²A₁g. These transitions are in agreement with the general observation that Cu(II) d-d transitions are normally close in energy.

 

EPR Spectra:

EPR spectra of copper(II) complexes were recorded on X band at a frequency range of 9.1-9.3GHZ under the magnetic field strength of 3000 G at liquid nitrogen temperature in frozen DMSO glass. Copper complexes exhibited well resolved anisotropic signal in parallel and perpendicular regions. The observed data showed that gII =2.10-2.25 and gI =2.03-2.12[table 3]. The gII and g̝̝I values are close to 2 and gII>gI it suggested major distortion from Oh symmetry in the copper complexes.

 

 

Copper Complexes with L1 Ligand Copper Complexes withL2 Ligand

Table 1 Molar conductance and elemental analysis data of binuclear Cu(II)  complexes

Complexes	M.W. Calc. (Found)	Molar cond. W-1cm2mol-1	Colour	Yield %	M.Pt.  °C	Elemental analysis  Calc. (Found)
						Cu	C	H	N
[Cu2L1Cl2]Cl2 Cu2C20H20N4S2O4Cl4	712  (711.72)	219	Green	55	190	18.25  (18.32)	33.70 (33.79)	2.80 (2.85)	7.85 (7.92)
[Cu2L1(NO3)2](NO3)2 Cu2C20H20N8S2O16	820  (819.89)	217	Green	52	183	15.85  (15.91)	29.26 (29.31)	2.43 (2.47)	13.65 (13.69)
[Cu2L1(SO4)2] Cu2C20H20N4S4O12	764  (763.19	12	Pink	70	162	170.01 (170.09)	31.41 (31.47)	2.61 (2.65)	7.32 (7.37)
[Cu2L2Cl2]Cl2 Cu2C18H18N6S2O4Cl4	714  (713.52)	221	Green	58	168	18.20  (18.27)	30.25 (30.29)	2.52 (2.57)	11.76 (11.83)
[Cu2L2(NO3)2](NO3)2 Cu2C18H18N10S2O16	822  (821.29)	232	Firozi Green	62	175	15.81  (15.89)	26.27 (26.31)	2.18 (2.21)	17.03 (17.09)
[Cu2L2(SO4)2] Cu2C18H18N6S4O12	766  (765.34)	15	Blue	57	181	16.97  (16.99)	16.97 (16.99)	2.34 (2.37)	10.96 (10.99)

 

Table 2 Electronic Spectral bands (cm^-1) of Binuclear Cu(II) complexes

Complexes	Spectral bands in cm-1	meff (B.M.)
[Cu2L1Cl2]Cl2	15462,  21701	1.61
[Cu2L1(NO3)2](NO3)2	15479,  21777	1.60
[Cu2L1(SO4)2]	15442, 21832	1.62
[Cu2L2Cl2]Cl2	15666, 22621	1.62
[Cu2L2(NO3)2](NO3)2	15672, 22980	1.60
[Cu2L2(SO4)2]	15698, 22874	1.54

 

Table 3 ESR Spectral data of Binuclear Cu(II) complexes

Complexes	g||	g^	giso	Aiso	A||
[Cu2L1Cl2]Cl2b	2.14	2.039	2.111	79.4	183
[Cu2L1(NO3)2](NO3)2b	2.24	2.060	2.117	78.7	182
[Cu2L1(SO4)2]b	2.32	2.062	2.115	81.2	184
[Cu2L2Cl2]Cl2b	2.17	2.059	2.118	81.9	185
[Cu2L2(NO3)2](NO3)2b	2.27	2.064	-	-	-
[Cu2L2(SO4)2] b	2.36	2.060	-	-	-

^aas polycrystalline sample at room temperature, ^bas Polycrstallien sample at LNT, ^c in DMSO  at LNT, g_^ = (3g_iso- g_||)/2,A_^= (3A_iso- A_||)/2

 

Table 4 IR Spectra bands of Binuclear Cu(II) complexes

Complexes	n(N-H)	Amide-I	Amide-II	Amide-III	Amide-IV	n(M-N)	Anion
[Cu2L1Cl2]Cl2	3305	1661	1539	1261	549	431	-
[Cu2L1(NO3)2](NO3)2	3297	1669	1545	1265	546	432	1432, 1318, 1008
[Cu2L1(SO4)2]	3299	1699	1546	1269	551	435	1160, 720
[Cu2L2Cl2]Cl2	3297	1651	1535	1261	549	407	-
[Cu2L2(NO3)2](NO3)2	3299	1665	1537	1265	553	409	1430, 1324, 1006
[Cu2L2(SO4)2]	3313	1665	1539	1263	551	417	1180, 760

REFERENCES:

1.        Massoud. S.S, Wiliam. G.F, Louka. F.R, Henary. M.M, Herchel. R, Travicek. Z, Fischer. C. R and Mautner. F. A: Croconato-bridged Copper (II) Complexes: 2017, Synthesis, Structure and magnetic Characterization. New J. of Chemistry.

2.        Malik. S, Ghosh. S, Jain. B, Archana. S, Bhattacharya, Synthesis, Characterization and Biological Evolution of some 3d-metal complexes of Schiff base derived from Xipamide drug. International. J. Inorganic Chemistry: 2013, Article Id 549805, 6pages.

3.        Prashanthi. Y, Kiranmai. K, Kumar. I, Chityala. S, Shivraj. V.K, Spectroscopic Characterization and biological activity of mixed ligand complexes of Ni (II) with 1, 10-phenanthroline and heterocyclic Schiff bases, Bioinorganic Chemistry and Applications: 2012, Article ID 948534, 8pages.

4.        Bajju.D.G, Katoch.S, Devi.G, Kundan.S, Ashu, Bhagat.M, Synthesis and Characterization of some new thallium (III) macrocyclic complexes and their biological studies. Main Group Met. Chem.; 2016, 39(1):19-29.

5.        Khalil. M.M.H, Ismail. E.H, Mohamed. G.G, Zayed. E.M, Badr. A, Synthesis and Characterization of a novel Schiff base metal complexes and their applications in determination of iron in different types of natural water, Open J. of Inorganic Chemistry; 2012, 2:13-21.

6.        Singh. D.P, Sharma. K, Parveen, Template Synthesis and characterization of macrocyclic complexes of trivalent metal ions derived from oxalydihydrazide and Isatin, Asian. J. of Chemistry; 2014, 26: 376-378.

7.        ABP Lever, Inorganic Electronic Spectroscopy, 2^nd Edition Elsevier, Amsterdam, NewYork; 1984, 553-571.

8.        Shukla. S, Chandra. S, Kumar. A, Synthesis, Spectral investigation and Biological evaluation of Novel Macrocyclic Ligand and its Transition Metal Complexes, European J. of pharmaceutical and Med. Research; 2016,5:303-309.

 

 

 

 

Received on 08.05.2017         Modified on 28.05.2017

Accepted on 14.06.2017         © AJRC All right reserved