STUDIES ON SOME METAL COMPLEXES OF SULPHUR AND NITROGEN CONTAINING LIGANDS

Abstract

The organic compounds containing salt forming groups are very useful from analytical point of view. These groups are (I)-COOH or -C0SH(II)-0H or -SH, (III) > NH, (IV) -SO H or SO^H, (V) -NOH or NOOH, (VI) - As(0H)? or -AsO(OH) The metal chelates of the ligands containing one or more groups of this type are also very important from medicinal, biologi cal and industrial point of view. The work described in this thesis deals with the studies on the metal complex of some sulphur and nitrogen containing ligands . Although scanty details are available on the metal com plexes of such type of organic reagents but a few of them have yet to be investigated to add to the present state of knowledge in this field. The present report comprises of the details on the metal complexes of the following ligandS (i) Terphthalic and dithioterphthalic acid (ii) Benzylmercaptoacetic acid. (iii) Dithiodiglycollic acid, (iv) Succinimide* (v) Phthalimide. (vi) Salicylidene-o-aminophenol. (vii) Salicylidene-o-aminothiophenol. The studies were planned merely to look into the structure and analytical behaviour of their metal complexes. A major portion of the investigation is devoted to the preparation, chemical analysis composition determination, -iiusing various physico-chemical methods of the complexes in the solution forms. But, whenever it has been possible to isolate a solid, their structural analysis has been done by various methods such as I.E., electronic spectra, magnetic and conductivity measurements and thermal analysis. In few cases mixed ligand complexes with ammonia and amines have also been studied. The present thesis has been divided into 3 sections viz. A,B and C. SECTION A- This section comprises of two chapters. The first chapter deals with the results on Cu(II)i Ni(II) and Co(ll) complexes of terphthalic and dithioterphthalic acid.The stoichiometry of the complexes was found to be 1:1(M;L) as determined by ampfrerometric and conductometric titrations. These complexes could be isolated in the solid form, and their composition was further confirmed by chemical analysis, D.T.A., T.G.A. and magnetic measurements. The formulae of the complexes were found to be as follows: E*(C8H4°4) 3°- 5H20 j gu(CgH402S2) J.6H?0 CNi(C8H404)^. l.5H20j [Ni(C8H402S2)n.3H20. [Co(C8H404)2.2H20 j |Co(CqHL^S,,)J.4H?0. The I.R. spectra of the ligands and their metal complexes reveal amarked shift in the vc=Q, vc_Q, and vc_Q+ V0-C=0 bands from 166° cm-1> 1410 cm"1 and 1270 cm"1 to 1570 cm ,1380 cm" and 1140 cm"1 respectively and the disappearance of vgH(2460 cm"1) which indicated the coordination •iiiof the metal through oxygen or sulphur. The reduced value of the magnetic moment(5; 1.5 B.M. ) in the case of copper(ll) complexes indicated their existence in the dirneric form. The values obtained in the case of Ni(ll) and Co(II) complexes lie within the range normally expected for their high spin complexes i.e. 2.8 and 4.2 B.M. respectively. The complexes were allowed to react with ethylene diamine in benzene, and the resulting products were analysed for the metal carbon and hydrogen which favoured the formulae of the type [M(en)3~|t or dt where M = Co (II) or Ni(ll), t =terphthalate and dt =dithioterphthalate and |_Cu(en)23t or dt. The structures of these complexes were also confirmed by magnetic and I.R. studies. These ethylenediamine complexes were stable only either in solid state or in alcohol, acetone, ether etc. but, decomposed in water separating out the parent acids (t or dt) as an insoluble ++ ++ part and \3(en)^"2 or[Cu(en)23] in solution. Second chapter of this section describes the metal complexes of benzylmercaptoacetic acid. The composition of Cu(ll), Ni(ll), Co(II), Ag(I) and Fe(IIl) complexes with this ligand has been determined amperometrically and conductometrically as 1:1 for Cu(ll), Ni(ll), Co(II) and Ag(l) and 1:1 and 1:2 for Fe(IIl) complexes. 1:1 complexes of these metals except Ag(l) have been isolated and their composition and structure also established by analysis and. magnetic susceptibility measurements. There was a marked shift in the carbonyl stretching frequency from 1700 cm"1 and 1450 cm*"1(ligand) -ivto 1600 cm and 1380 cm (complex) respectively and the disappearance of vg_H band pointing towards the coordination of the metal through oxygen and sulphur. Benzylmercaptoacetic acid has also been used as an analytical reagent for the amperometric determination of Fe(III), Co(II) and Ag(l), 5.58 ppm to 139.60 ppm of Fe(III), 11.70 ppm to 117.80 ppm of Co(II) and 21.57 ppm to 215.70 ppm of Ag(l) can be determined with an accuracy of +0.5*/, Pb(ll), Cu(II), citrate,tartrate and salicylate interfered in the estimation of Fe(II), Cr(III), Fe(II) and CN~ in the estimat ion of Co(II) and Pb(II), Ni(II), Bi(III), halides, M0o£~ and WO* in the estimation of Ag(I). SECTION B- This section also comprises of two chapters. In the first chapter are incorporated the results of studies on some new aspects of metal imide complexes. The complexes DMPh^H, [Fe(Ph)3(Am)3^,[Fe(Ph)3(en)(H20)3, [FeCsucc^ ], |Fe(succ)3AmJand [Fe(succ)j(en)H20]] where Ph=phthalimide, en=ethylenediamine, succ=succinimide, am=Ammonia, methylamine or ethylamine, were prepared and characterised on the basis of chemical analysis, conductance measurements, I.R. and magnetic studies. Mossbauer studies of all these complexes were carried out and the values of chemical shifts (b) and quadrupole splitting (AE) were calculated. In the complexes of the type [Fe (imide ^An^ "2 , there was a decrease in isomer shift and increase in quadrupole splitting which -vindicated the greater electron density at the nucleus in comparison to FeCl^j 6H?0„ No appreciable difference in the isomer shift of [Fe (imide J^H and [Fe (imide ^Am^ J indicated a very weak coordination of the amines to the metal. Second chapter of this section deals with the prepara tion and characterisation of the complexes having a general formula [Co(succ )^(Am)2 "2 , where succ = succinimide (deprotonated), Am = ammonia or aliphatic amine, in solution as well as in solid state. Spectral studies and magnetic measurements indicated a tetrahedral structure for these complexes. They are stable in chloroform but disproportionate in nitromethane which can be represented as follows: _ 2+ ' o 2JCo(Am)2X23+(6-x)S -^ [Co(Am)x(S)6_x | +CoX^ + (4-X) Am where, X = deprotonated succinimide S • nitromethane Am = ammonia or aliphatic amine. * SECTION C- This section also comprises of two chapters The first chapter describes on the Ce(IV'), Th(IV), U02(II), Al(III, and Fe(IIl) complexes of salicylidene-o-aminophenol. All the spectrophotometric methods indicated the formation of 1:1 complex in each case. Out of these, only two complexes i.e. od Ce(lV) and Th(IV) could be isolated in the solid form and were analysed chemically.The formulae of these complexes were found -VIto be [Ce(C13H902N)2(0H)2H203 and JTh(C^H^N)(OH)?(H?0) ]. The structures have been discussed on the basis of I.R. studies and conductance measurements. The reagent has also been used as an indicator for the photometric determination of Fe(III). Cobalt(II), nickel(Il), bismuth(III), antimony(III) and aluminium(III) which interfere in the case of salicylic acid, tiron and pyrocatechol violet, do not interfere in this present method. Solutions containing Fe(IIl) from 50 ppm- 600 ppm can be determined accurately. In the second chapter of this section are incorporated the results of studies on Pd(II), Hg(I and II) and Ag(I) complexes of salicylidene-o-aminothiophenol. This Schiff's base derived from o-aminothiophenal and salicylaldehyde has been used for the amperometric determination of Pd(II) (at an applied voltage of -0.44 V^Vs SCE), Hg(I and II) and Ag(l) (at -0.55V, VS SCE) using d.m.e. as the indicator electrode. 12-12.3 ppm of Pd(Il), 60-100 ppm of Hg(ll), 120-200 ppm of %(l)> and 50-108 ppm of Ag(I) can be determined with an accuracy of + 0.5'/. . A number of foreign ions including Pt(IV), Ir(IlO, Au(III) and Bi(IIl) do not interfere even if present in 5-10 fold excess while traces of Ru(Hl) and Rh(IIl) interfere. All the complexes could be isolated in the solid form and were characterised on the basis of chemical analysis, conductance measurements and I.R. studies. -vii- APPENDIX This part of the thesis also includes two chapters. The first chapter describes the metal complexes of dithio diglycollic acid and its use as a new analytical reagent for the amperometric determination of Ce(IV),Fe(lIl),Hg(Il) and Hg(l). Solutions containing as little as 10 ppm of metal ion can be accurately determined with an error of +0.5/ . The traces of Th(IV), Mo(Vl) and W(VI) interfere. Halides do not interfere in the estimation of Ce(lV), Fe(III) and Hg(ll) but seriously interfere in the estimation of Hg(l). All the complexes have been isolated in the solid form and were analysed chemically. The formulae of the complexes were found as follows: H[Fe(C4H404S2)2(H20)2n i Hg[ggCC^O^)C12 U H2 [Hg2 (C4H404S2 )2 2 ; [Ce(C^O^)(NO3)£ The second chapter of this part of the thesis deals with the preparation and characterisation of pyrophosphate complexes of Cu(II), Ni(ll)s Co(II) and Fe(IIl) on the basis of their electronic spectra, conductance, magnetic measure ments and I.R. studies. The values of 10 Dq, B and P (nephelauxetic ratio) for Na2[Co(H?P207)2(H20)?"] HO weifc found to be 13705 cm"1, 861 cm"1 and 0.88 and for Na?|Ni(H2P20y^HpO)^ H?0, 10000 cm , 801 cm and 0.77 respectively.The absorption spectra of iron complex,Na [Fe (H2P20-, )2(H20)o^ 2Ho0 gave a double peak at 12000 cm and of copper complex,Nai?2T"?[uCu((HHp2PP020077))2"1_ Ho0 gave two bands at 13890 cm 1 and 26000 cm -1. Cu(Il), Ni(ll), Co (II) -Vllland Fe(IIl) complexes were found paramagnetic with a magnetic moment of 1.87, 2.90, 5.00 and 5.90 B.M. respectively. The stretching bands due to O-P-0 at 540 cm"1 and due to P-0-P at 940 cm were obtained in the I.R. spectra of all the complexes.