STUDIES ON THE METAL COMPLEXES OF SOME ORGANIC ACIDS, AMINES AND ACID-IMIDES

Abstract

The work presented in this thesis is on the interaction of transition metal ions with organic ligands containing one or more salt forming groups e.g. (I) -COOH (II) -NH (III) - OH etc. The metal chelates of such ligands have been widely used in the medicinal, biological, analytical and industrial fields. Thus acids and imides have been used as primary ligands and heterocyclic amines, interhalogens and cyanogenbromide as secondary ligands. The thesis is devoted to the preparation of mixed ligand complexes and their characterisation on the basis of chemical analysis, conductance, I.R., electronic spectra and magnetic measurements. Detailed magneto-chemical analysis at varied temperatures and thermal analysis of some of the complexes also constitute a part of the thesis. The thesis has been divided into two sections viz., A and B. SECTION - A This section comprises of three chapters. Chapter - I : This chapter deals with the preparation and characterisation of mixed ligand complexes of titanium (III) ii and vanadium (IV) with imides and heterocyclic amines. The complexes of the type [VO(P or S)2L ], [Vo(P or S) L? (H20)], [VO(P or S)OX(H20)2], [Ti(P or S)3L3], [Ti(p or S)3L* (H20)] and [Ti(P or S)20X(H20)2] where PH • phthalimide, SH = succinimidej L = quinoline, i t isoquinoline, 2-picoline or pyridine? L = 2,2 -bipyridyl, 1,10-phenanthroline or 2-aminopyridine and HOX = 8-hydroxyquinoline, were prepared and characterised on the basis of elemental analysis, conductivity and magnetic measurements and infrared and electronic spectroscopic studies. All the complexes were found to have an octahedral structure. I.R. spectra of the complexes indicated the coordination of imides through nitrogen. The presence of water molecules inside the coordination sphere could be confirmed from the I.R. and thermal studies of the complexes. Chapter - II : This chapter describes the studies on the pentacoordinated complexes of cobalt (II) and nickel (II) with imides and amines. The complexes of the type [M(imide)2(L)] where M = Co(ll) and Ni(ll), imide = deprotonated phthalimide or succinimide and L = terpyridyl or diethylenetriamine, were prepared and iii characterised on the basis of elemental analysis, I.R., electronic spectra, magnetic and conductance measurements. There was a shifting in carbonyl stret ching frequency from 1750 cm" to 1620 cm" in the spectra of complexes. This negative shift was due to the mass effect. The shifting of c„ stretching frequency from 1470 cm to 1500 cm" in the spectra of complexes indicated the coordination of the imide ion. The magnetic moments of Co(Il) complexes with terpyridyl lie in the range 3.99-4.12 B.M. at room temperature which is consistent with the values of pentacoordinated complexes. But the values of magnetic moments of Co(ll) complexes with diethylenetriamine were found 1.55 and 1.56 B.M. indicating the formation of low spin complexes. The magnetic moments of nickel (II) complexes lie in the range 2.60-2.70 B.M. which are in good agreement with the published values. The electronic spectra of nickel (II) complexes showed four bands in the range 8100-8700 (v±), 10200-11000 (v2), 14500-16000 (v3) and 22500-23500 (~»A) cm"1 while Co(ll) complexes gave three bands in the range 9200-10650 (v ±) , 16800-17500 ( v2) and 22200-23250 (* 3) cm"1. This also indicated the formation of pentacoordinated complexes. iv The complexes, however, have lower symmetries and are moderately distorted. Chapter - III : This chapter deals with the mixed ligand complexes of copper (I), silver (I), palladium (II) and mercury (II) imides with interhalogens and cyanogen-bromide. The complexes of the following compositions were prepared : [Pd(P or S)2(l-l')2], [Hg(P or S)2(l-l')2], [Cu(P or S) (I-l')3, [Ag(S)(I-l')3] and [Ag(P)(I-I*)] where P= deprotonated phthalimide and S = deprotonated succinimide and I-l' = interhalogens or cyanogen-bromide. These complexes have also been characterised on the basis of physico-chemical techniques mentioned earlier. The I.R. spectra confirmed the coordination of metal ion with the nitrogen of imide ion. The bands of IBr and IC1 at 260 and 365 cm"1 shifted to » 245 and ~ 320 cm" respectively in the spectra of complexes. Similarly the bands of CNBr observed at 570, 360 and 2180 cm" also shifted to 550, 350 and « 2165 cm"1 respectively and hence confirm the coordination of interhalogens and CNBr with the metal ions. All the complexes were diamagnetic in nature. The solution spectra of palladium (II) complexes in acetone gave the bands atw 23000,2 28500, «kr31000, 3534500 and s» 40000 cm" corresponding to the transitions A-^ > /^ » A.^ > B^ , A. > E , 1A. • A- and A, • E respectively. The values lg 2u lg u of A., a_ and a3 were calculated. The solution spectra of other metal ion complexes fall in the range of ^31000 to 2** 41400 cm which may be due to charge transfer transitions. SECTION - B This section also comprises of three chapters : Chapter - I : This chapter deals with the preparation and char acterisation of mixed ligand complexes of Co(Il) and Ni(Il) with diphenic acid and heterocyclic bases. The complexes of the composition [M(DA)(L)4], [M(DA)(l')2],[Co(DA)(APy)], K[Co(DA)(OX)] and K2[Ni(DA)(OX)23 where DA = deproto nated diphenic acid; L = quinoline, pyridine? L* = isoquinoline, APy = 2-aminopyridine; HOX = 8-hydroxyquinoline and M = Ni(II) and Co(Il) have been prepared. They were analysed chemically for the metal, carbon and hydrogen. Their structures have been determined by carrying out spectral and magnetic studies. The elect ronic spectra of Co(ll) complexes with quinoline and pyridine gave two bands at m16000 cm" ( v 2) and VI « 18500 cnT1(v 3) corresponding to the transitions 4VF>—+%3('2~> and4Tlg(F)—^lg(P)l»3) res pectively. The transition 4Tlg(F) •T2g(F)(*1) was calculated by assuming the transition ratio 2/ ^ m 2.1. In the case of 8-hydroxyquinoline and 2-amino pyridine complexes, two bands were observed at ~ 24000 and £ 3C,000 cm corresponding to the trans itions 4A2g(F) »4Tlg(P)( v3) and charge transfer respectively. From the spectral analysis it is evident that the Co(ll) complexes with quinoline and pyridine were octahedral and with hydroxyquinoline and aminopyridine were tetrahedral which were also confirmed by the magnetic measurements at varying temperature. The isoquinoline complexes of Co(ll) gave three bands at 22500, 27800 and 29000 cm""1 corresponding to the transitions \g ^A^, \g—^\g and Sg—*% respectively indicating a square planar structure. The Ni(ll) complexes except with isoquinoline gave three bands at £ 9000, £ 15500 and #28500 cm* corresponding to the transitions A2 (F)—» T2g(F)(vx), A2g > 3Tlg(F)(^2) and 3A2g(F)—->3Tlg(P)(*3) respectively, The values of magnetic moment were found in the range 3.0 - 4.0 B.M. The analysis of the electronic spectra vii indicated the distortion of Oh symmetry. The isoquino line complex of Ni(Il) was diamagnetic and its electronic spectrum in methanol consisted of three charge transfer bands indicating a square planar structure. The I.R. spectra indicated the coordination of metal ion with the carboxyl groups. Chapter - II : This chapter is devoted to the preparation and characterisation of mixed ligand complexes of copper (II), palladium (II) and platinum (II) with diphenic acid and heterocyclic amines. The complexes of the composition [M(DA)L] and [m(DA)(l')2] where M=Cu(ll), Pd(ll) and Pt(ll); L = 2-aminopyridine and L = quinoline, pyridine and picoline have been prepared. They have been characterised similarly on the basis of above mentioned physico-chemical techniques. All the complexes of Pd(ll) and Pt(Il) are diamagnetic indicating their square planar structure while copper (II) complexes are paramagnetic with one unpaired electron. In the case of Cu(ll) complexes three bands at 15500, 19500 and 22000 cm~ 2 9 are obtained corresponding to the transitions Big"~—* Aig» 2g ___>2e and charge transfer respectively which lg g Vlll indicate their square planar sterochemistry. Palladium (II) complexes gave four bands at 23000, 29300, 31500 and 34600 cm" and Pt(Il) complexes gave three bands at 36000, 39500 and 41000 cm respectively indicating their square planar structure. The three orbital parameters A,, a2 and a3 for Pd(II) and Pt(ll) com plexes were calculated using the orbital and interelectronic repulsion energies of excited states for d square planar complexes. Chapter - III : This chapter describes the preparation and characterisation of mixed ligand complexes of Co(ll) and Ni(ll) with homophthalic and tetrachlorophthalic acids and heterocyclic bases. The complexes of the type [M( A)(L)4], [M(A)(l')2] and [M(A)(l")] where M = Co(ll), Ni(Il); L = quinoline, isoquinoline, pyridine, t ii picolinej L = 2-aminopyridineJ L = dipyridyl and o-phenanthroline and A = deprotonated homophthalic or tetrachlorophthalic acids have been prepared and char acterised. I.R. studies confirmed the coordination of acids with the metal ions. The values of magnetic moments at different temperatures and electronic spectral data indicated a tetrahedral structure for the dipyridyl and o-phenanthroline complexes of Co(II) and a square planar structure for the complex of Ni(II) with homophthalic acid only while all other complexes were of octahedral structure.