Chapter 6

Synthesis and Characterisation of Polymer Supported Mixed Ligand Complexes

T he preparation of mixed ligand complexes in homogeneous conditions

encounters difficult~es due to the incomplete conversion of reactants. The

formation constant of the mixed ligand complex is decisive in this aspect and when

the mixed ligand complex is prepared by mixing two parent complexes the

formation constant should be having appreciably higher value to get a single

species in solut~on. For mixed ligand complexes like Cu(en aca)' and Cu(aca dgH)

[en-ethylene diarnine, aca-acetyl acetonate, dgH-dimethyl glyoximate], the

experimentally obhned formallon constant value is very much lower than the

required value and in the preparation of these complexes due to the comparatively

smaller values of K, the reaction is incomplete1 To overcome such difficulties

encountered in homogeneous conditions we tried to prepare mixed ligand

complexes on polymer supports. Actually we wanted to incorporate the interesting

s t ~ c t u r d and electronic features of the coordination frame work containing the

mixed ligand system and the stability factor exerted by the polymer network. The

following section deals with the preparation and characterisation of mixed ligand

complexes on polymer supports.

6.1 Preparation of polymer supported mixed ligand complexes

Two procedures were adopted for the generation of mixed ligand complexes

on polymer supports. ( 1 ) Treating the polymer metal complexes described in

Chapter 5 (precursor complex) with respective secondary ligands and (2) treating

the polymeric llgand w~th stable metal complexes.

6.f.l Reaction behueen precursor complex and ligands

A known we~ght of the polymer metal complex (precursor complex) was

stirred with a solut~on of the secondary ligand in a suitable solvent. The mixed

ligand complexes could be formed according to the following equation. Both the

presence of anlons and the number of anionic species present depend on the charge

A L of the 11gand funct~onr (* and ( L .

The secondary l~gands used are acetyl acetone, 8-hydroxy quinoline,

ethylene diamlne, dithiocarbamate, oxalate, phthalate and acetate. The addition of

the secondary ligand to the precursor complex does not assure the formation of

mixed complex on polymer support. In some cases the addition of a secondary

l~gand causes the metal ion to get leached from the polymer forming the metal

complex of the added ligand in solution. The results obtained are summarised in

Table 6.1. Some important observations made in this aspect is note worthy. The

addition of oxalate to polystyrene supported ethylene diamino nickel complex

[P*NN(NiS04)] produces nickel oxalate in solution. Similarly the addition of

8-hydroxy quinol~ne to polystyrene supported ethylene diamino copper(I1) complex

produces Cu(SHQ)2, whereas the additions of oxalate to the same precursor

complex produce mixed l~gand complex on polymer support. These observations

can be explruned by taking into account the formation constants of metal

complexes of the concerned ligand systems. The formation constants of the metal

complexes of the rnvolved ligands are listed in Table 6.2. The results obtained can

be interpreted as follows For a mixed ligand complex to be formed according to

zquatlon ( 6 . I ) .

This generallsation can be illustrated as follows. KCu(8HQk and

&Cu(en)~" are almost same. So the addition of 8HQ to the precursor complex

polystyrene supported ethylene diamino copper complex [P*NN (CUSO~)] will

make the copper to come out of the polymer as Cu(8HQ)2. Since ~ t ~ u ( e n ) Z % >

I ( ~ C U ( O X ~ ~ . the addition of oxalate to the precursor complex P*NN(CuS04)

produce the m~xed complex, P*NNCuOx on polymer. When nickel salt

P*NN CNiS04) is used smce ~tNi(en)2'' = ~ t N i ( 0 x h " the addition of oxalate

produce W~(OX)~]'- In solution.

Table 6.1

Precursor complex

1 Polystyrene supported dlthiocarbamato Cu(l1) complex

Secondary ligand

1. Ethylene diamine

2. Acetyl acetone

3. 8-Hydroxy quinoline

4. Diethyldithio- carbarnate

5. Oxalate

Result

Violet colour imparts to the solution indicating the formation of [~u(en)~]'' and the polymer becomes wlourless due to the leaching of copper ions into the solution

Green colour imparts to the solution and the colour of the polymer beads also gets changed to green. Successive washing with ethanol and chloroform produces colourless polymer beads by dissolving the Cu(acac)z formed on the surface of the beads.

Green wlour imparts to the solution as well as polymer beads. Washing with ethanol and CHC$ dissolves the green complex on the polymer which is identified as Cu(8HQ)z.

The polymer beads become brown , coloured. On washing the polymer 1 with CHCI, Cu(diethy1 d tc )~ is 1 formed in the solution producing colourless beads.

[cu(ox)212- is formed in solution

7. Acetate

6 Phthalate

Colour of the polymer beads slightly changed. But washing with almost all the solvents retains copper in the polymer indicating the formation of mixed chelate on the polymer [PtSS CuAce].

[~u(~hthalate)2]~' is formed in solution

2 Polystyrene supported ethylene diamine Copper(1I) complex P*NN(CuX)

-

3 Polystyrene supported ethylene diamine nlckel(I1) complex -

4 Polystyrene supported acetyl acetone copper(1l) complex PI * 0 0 ( C u S 0 ~ )

1. Ethylene diamine

1 2 Acetyl acetone / Cu(acac)z is formed I 3 . Diethyl- Cu(diethy1 dtc)2 is formed dithiocarbamate I 5 . Oxalate

Cu(8HQ)z is formed

changed and the copper does not come out into solution on repeated washing indicating the formation of mixed chelate on the polymer. IP*NNCuOxl

1. Ethylene [cu(en)212' is formed diamine

6 phthalate

7 acetate

I 7 Acetyl acetone I Cu (acac)2 is formed

Mixed complex of phthalate is formed on the polymer [PINNCuPht].

Mixed ligand complex is formed on the polymer [P*NNCuAce]

Same observation as in the case of copper(I1) except for oxalate in which case [N~(OX)~]'- is formed in solution

3 8 H Q

4. Diethyl dithiocarbamate

Cu (8tIQ)z is formed

Cu (diethyl d t c ) ~ is formed

1 7. Acetate I PI*OOCuAce is formed I

5. Oxalate

6. Phthalate

I 5 Polystyrene supported I 1 Acetyl acetone I VO ( a c a ~ ) ~ is formed I

Mixed ligand complex is formed PI *00Cu(0x)

PI*OOCuPht is formed

ethylene diamine VO(I1) complex. P*NN(VOS04)

1 2.8HQ I V 0 (8HQ)z is formed

4. Phthalate

3. Oxalate

5. Acetate

VO(oxalate) is formed

Mixed complex is formed P*NNVOPht

Mixed complex is formed P*NNVOAce

Table 6.2. Formation constants of metal complexes2

r-. Complex log K2

t ~i(Ox)2'

Ni(acetate)>

Ni(phthalate)2'.

7.64

1.81

2.14

*Value arbltrar~l? given

6.1.2 The addition of polymeric ligand to stable metal complexes

A known wetght of the polymeric ligand was added to a solution of metal

complex St~rred or heated as required. Mixed complexes are formed according to

the followtng equatlon T h ~ s was separated and purified by suitable methods.

Whether the structure A or B is formed is determined by the charge on the ligands

Var~ous attempts were done to prepare mixed ligand complexes and all the

nuxed ltgand complexes were successfully formed. The structure of the complex

and also the number of ltgands tnvolved depends on the charge of the Ligands. The

con~plexes prepared are listed in Table 6.3.

Table 6.3.

Mixed ligand complex r 1 Polymer supported l~gand k-

Metal complex

Cu(acac)~

I i L

6.2 Characterisation of polymer supported mixed ligand complexes

The mixed ligand complexes prepared as in Section 6 1 were charactensed

by spectroscopic methods The IR, UV-VIS and ESR spectra of the complexes

were recorded The bonding pattern, perturbations in the electronic energy levels

and stability of the complexes were studled from the spectral results The important

spectral results are summarised and interpreted tn the follow~ng sect~ons

6.2.1 Oxalato polystyrene supported ethylenediamino copper(l1) complex PNNCuOx

Mixed ligand complex was prepared by stirrtng the precursor complex,

P*NN(CuSO1) with potassium oxalate solution. The resultant mixed complex was

purified by repeated washing with suitable solvents, dried and kept under vacuum.

This was subjected to spectroscopic analysis,

Scheme 6.1

IR spectroscopy 1s efficient in determining the atoms involved in

co-ordination and to establish the mode of co-ordination of the ligands. The

vibrattonal frequenc~es of the ~ O N C ligands changes upon co-ordination and the

nature of coordinated l~gand can be studied from IR spectra The IR spectrum of

the metal complex P*NN(CuS04) contains characteristic peaks at 1120 cm" and

620 cm-' corresponding to the S=O stretching vibrational frequencies cf ionic

sulphate. In the spectrum of mixed Iigand complex peaks at 1120 cm" and

620 cm-' are absent and two new peaks are observed at 1295 and 1670 an-'

(Figure 6.1). These peaks are characteristic of bidentate oxalate group. Ionic

oxalate absorbs at 1305 cm-' (C-0 sir) and 1600 cm-I (C=O str).' The C-0 bond

strength decreases on complexation which suggest the c u o r d i i o n of oxalate

through C-0 group and the absence of peaks due to ionic oxalate suggest bidentate

m r h n a t i o n Since oxalate is binegative, its co-ordination to cuZ+ ions removes

sulphate fhm the complex which is indicated by the absence of peaks

corresponding to sulphate Ions.

W V E NO. ( ~ d

Figure 6.1. LR spectrum of the mixed complex P*NNCuOx

On forming the mlxed llgand complex from the precursor complex the

characterlst~c I!\ absorptlon peak of the precursor complex shows a considerable

sh~fi 1 h ~ s difference in U\' absorptlon IS due to the difference in crystal field

spllttlng produced bv the co-ordlnated water molecule and the secondary ligand

L~gand whlch 1s stronger than water causes larger spllttlng of energy levels

whereby shlfts the UV absorptlon to h~gher wavenumbers (Flgure 6 2) The shlfi In

absorptlon peaks depends also on the nature of the secondary llgand The

rr-electron density of the llgand whlch can Interact wlth the metal orbltals 1s

decislve In thls aspect

WAVE LENGTH ( N M )

Figure 6.2. Electronic spectra of (a) P*NN(CuSO.,), (b) P*NNCuOx, (c) P'NNCuPht, and (d) P*NNCuAce.

On formlny the mixed ligand complex P*NNCuOx from the precursor

complex P*NN(CuSOq) the transition that is greatly affected is the 2 ~ 1 , -+ 2 ~ l g

tlansltlon Thls characterlstlc absorption (dz2 + d ~ ~ - ~ ~ ) of square planar Cu(I1)

c d ~ n ~ ~ l e x e s 1s observed at 15777, cm" in P*NN(CuS04) and at 161 55 cm-I in

I'*NNCuOx complex B + A transition corresponds to the excitation of an

electron from nonbonding dz2 orbital to antibonding dx2-y2 orbital During mixed

l~gand complex formation the co-ordinated water molecules in the precursor

complex are replaced by the oxalate ligating group which cause greater ligand field

splln~ng due to Increased thermodynamic stability of the complex whereby placing

the b,,* orbital at a h~gher level and thus increasing the al, + bl,* energy gap. The

interaction of the x-elecuon cloud of the oxalate group destabilises the d: orbital.

The Increase in energy of the d: orbital decreases the a,, + bl,* energy gap and so

the transit~on energy will decrease to some extent.

ESR parameters obtained for the complex correspond to square planar

stereochemistry The ESR parameters are = 2.2476, = 2.0939, 4, = 165 A,. =

63.3 and a'= 0 7794 The parameters vary slightly From the values obtained for the

precursor complex P*NN(CuS04). Even though the copper environment in both

the complexes are CuN202 the cr and x donor strength of oxalate group is different

from that of water molecule and hence the covalent character of the bonds may be

different A typ~cal ESR spectrum is shown in Figure 6.3.

MAGNETIC FIELD

Figure 6.3. ESR spectrum of P*NNCuOx

6.2.2 Phthalato polystyrene suppotted etfrylenediamino copper(1Ij complex

The precursor complex, P*NN(CuS04) was made to react with potassium

phthalate solution to get the mixed ligand complex as illustrated in Scheme 6.2.

The complex was purlfied by repeated washing, dried and kept in a desiccator.

Scheme 6.2

In the IK spectrum of the m~xed l~gand complex peaks due to lonlc sulphate

x e absent ~ h l c h lndlcates the blnegatlve nature of phthalate group (Flgure 6 4)

Peaks at 1380 cm ' [ v (C -0 ) ] and 1560 cm [v(C=O)] are due to co-ord~nated

phthalate and its b~derltate nature IS ev~denced from the absence of peaks due to

mnlc phthalate '

Figure 6.4. IR spectrum of P*NNCuPht

The UV spectrum of the mixed ligand complex shows an absorption peak

at 15923 cm" which is attributed to the dzZ 4 dx2-y2 transition. The blue shift of

thts band on compartng with the precursor complex is due to greater ligand field

splittrng. The at, + bl,* transition energy is greater for P*NNCuOx in comparison

w~th P*NNCupht. Thts difference in energy for dzl -+ dx2-yZ transition is

attributed to the difference in the destabilisation of d 2 orbital by the n-electron

Interactton of the secondary ligand. Since the n-electron density of phthalate group

8s greater than that of oxalate group, the dzZ orbital is more destabilised in phthalate

complexes whtch decrease the energy gap and hence transition energy of al,-+bt,*

transition (Figure 6 . 2 ) ~

Obmned ESR parameters are = 2 265, g~ = 2 094, Ail = 160, A1 = 60 and

a' = 0 7322 The change in ESR parameters as compared to the precursor complex

1s due to the co-ord~natton of the stronger ligand phthalate tnstead of water

molecules (Ftgure 6 5 )

U O N F T T C P1RI.D

Figure 6.5. ESR spectrum of PINNCuPht.

The magnetic parameters are characteristic of a CUN202 chromophore in a

.strong tetragonally distorted octahedral field. The two apical solvent molecules

h n g surely confined to longer distances.

6.23 Acetat0 pdysfyme supported ethylene diamino cwerflll) w l e x

On stirring the precursor complex P1NN(CuS04) with sodium acetate

solution mixed ligand complex was formed according to the following scheme.

This was purified and dried by usual experimental methods.

Scheme 6.3

The 1R spectrum of the mixed ligand complex contains peaks at 1120 cm.'

and 620 c m ~ ' due to lonlc sulphate (Figure 6 .6 ) and peaks at 1395 cm'l and 1600 -1 cm are attr~buted to co-ordinated acetate. The difference in the absorption

frequency of the two peaks due to acetate (Av value) suggest unidentate 3 co-ord~nat~on of acetate group The presence of ionic sulphate indicates the

LO-ordination of only one acetate group to copper ions in the complex.

Figure 6.6. 1R spectrum of P*NNCuAce

The characteristic UV absorption peak is observed at 16366 cm". The

transition is attributed to 'BI, -+ 2 ~ l g . The x-electron density of the ligands is in

the order phthalate > oxalate > acetate and hence the extent of destabilisation of

the d: orbital is also in the same order. This explains the decrease in the energy for

dZ2 + d:-; transition in the mixed ligand complexes in the order PtNNCuAce>

P*NNCuOx > P*NNCuPht (Figure 6.2).

The ESR parameters confirms square planar stereochemistry and the

parameters are g = 2.23 A = 170, = 2.081, A1 = 70 and a2 = 0.7966

(Figure 6.7). The g values and A values indicate the presence of unpaired electron

in the dx2yZ orbital The a2 values for the mixed complex vary in the order

P*NNCuAce > P*NNCuOx > P*NNCuPht. This trend can be attributed to the

difference in o donor strength of the three secondary ligands in the order phthalate

> oxalate > acetate.

Magnetic field '

Figure 6.7. ESR spectrum of P * N N C ~ A C ~ .

6.2.4 Acetato polystyrene supported dithiocarbamate copper (11) complex

The reactlon between polystyrene supported d~thtocarbamate copper(I1)

complex and sodium acetate solut~ons produces the m~xed l~gand complex The

reactlon sequence is dep~cted in Scheme 6 4

Scheme 6.4

In the IR spectral analysis of the mixed ligand complex it is seen that the

peak at 1380 cm-' present in the precursor complex [P*SS(CuNO3)] disappears and

two new peaks are generated at 1395 cm" and 1600 cm-I. The peaks correspond to

unidentate acetate and since dithiocarbarnate function is uninegative, one acetate

group will be co-ordinated to the copper atom.

The d,' -t d:-,' transition observed at 14214 cm-' in the precursor complex,

P*SS(CuNO>), sh~fted to 15220 cm-' in the mixed ligand complex P*SSCuAce.

fhe co-ord~nat~on of an acetate group instead of water molecule will increase the

ltgand field spl~ntng whereby increasing the d; + d:-: energy gap (Figure 6.8).

w U z ! a m 1 a 0

i

w. I m 1 4 I - O. lOA L

zoo 0 100 O{NM/D/V) PO00

WAVE L E N G T H (NM)

(a)

WAVE LENGTH ( N M )

Figure 6.8 Electronic spectra of (a) P*SS(CuNO:) and (b) P'SSCuAce

ESR parameters obmned for the complex are g = 2.1085, g~ = 2.023,

A = 142, Al = 22 4 The spectral parameters are lndlcative of a CuS202

chrornophore

6.2.5 Ace$& pdystyrene supported acetyl acdPnato copper(//) complex: PIWOCUAC~ The above m~xed complex was prepared by refluxing the polymeric ligand

polystyrene supported acetyl acetone (P1*00) with copper acetate solution. The

complex obtiuned was collected, purified and drled. The reaction sequence is

shown in the following scheme.

Scheme 6.5

The mixed ligand complex was analysed by spectral methods. The

formation of the complex was evidenced from IR spectrum. The iR spectrum of

the ligand changes upon coordination (Section 5.6.b). The peaks at 1390 cm-' and

1609 cm-' are attributed to coordinated acetyl acetone and the peaks at 1380 crn-'

and 1600 cm' are due to coordinated acetate (Figure 5.15).

The solid state UV spectrum of the complex e x h ~ b ~ t a well defined peak at

12662 cm ' whlch is due to the dz2 -+ d ~ ~ - ~ ~ transition in square planar complexes

1 he ESR parameters obtaned are g = 2 304, g~ = 2 053, A = 130, AL = 53 3 and

u 2 = 0 6849 (Figure 5 16) The y and A values are in agreement with Cu04

environment and the a' value suggest covalent nature to ~nplane a bondlng

6.2.6 Phthalato polystyrene supported ethylene diamino oxovanadium(ll) complex PNNVOPht

The preparation of the m~xed complex lnvolves the reaction between the

precursor complex PtNN(VOS04) and sodium potassium phthalate The react~on is

shown in the followlny scheme

CH2-H2C, / + a C O O K

COONa

Hz0 OH2 so:-

Scheme 6.6

The complex was synthesised according to the above scheme and the

product was punfied and subjected to spectral characterisation. Peaks at 1120 cm-'

and 620 cm.' (due to lonlc sulphate) present in the IR spectrum of precursor

complex are absent in the IR spectrum of the mixed complex (Figure 6.9) and two

new peaks are observed at 1380 cm-' and 1560 cm-I which are attributed to the

bldentate phthalate [v(C-0), 1380 cm-I and v(C=O), 1560 ern-'1.

, ta0.a , 3 0 ~ . , 7 cn00.n 1 5 o o . r l :ooo .o 400.0

Wave Number (cm-' )

Figure6.9. IR spectra of (a) P*NN(VOS04), (b) P*NNVOPht and (c) P'NNVOAce.

The electronic transrtion that undergoes considerable change during the

formatron of mrxed lrgand complex is the b2 -t a,* transition (Figure 6.10). This

transltron 1s observed at 22 172 cm-' in the m~xed complex whereas in the precursor

complex the transltron is observed at 21097 cm- ' On forming the mixed complex

the co-ordinated water molecules are replaced by the w-ordinated phthalate entity

and its greater llgand field strength causes greater splitting of the energy levels and

therefore, a blue shift in the electronic spectrum. These features are shown in

E~gure 6.10.

Figure 6.10. Electronic spectra of (a) PSNNVOPht and (b) P*NNVOAce.

Solld state ESR spectrum of the complex was recorded at room temperature

and the ESR parameters are g = 1 9542, A = 185 7, a = 1 9655 and A, = 70,

P?: 1 0062 The well resolbed ESR spectrum recorded at room temperature

clearly ~ndrcat~ng the h~gh stabil~ty of the m~xed l~gand complex (F~gure 6 11)

MGNETIC PlLLD

Figure 6.1 1. ESR spectrum of P*NNVOPht

6.2.7 (Acetato)@&styrene suppatted ethylene diamino) vanadyl complex

Mixed complex was prepared by treating the precursor complex

P*NN(VOS04) with sodium acetate (Scheme 6.7).

Scheme 6.7

In the IR spectrum of the complex peaks due to co-ordinated acetate are

present at 1380 cm~' and 1600 cm-I, and peaks due to ionlc sulphate are present at

1 1 20 cm-I and 620 cm-' (Figure 6.9). The presence of sulphate suggest the co-

ordlnat~on of one acetate group.

The b2+alt trans~tion observed at 22321 cm-I in the mixed complex

suggest a five co-ordinate stereochemistry and this transition occurs at a hlgher

frequency than in the precursor complex due to higher crystal field splitting

produced by acetate (F~gure 6.10)

The complex gave a well resolved anisotropic ESR spectrum with the

following parameters g = 1.9322, = 1.9801, A = 174, A1 = 59, ~ 2 ' = 0.9353.

6.2.8 (Acetyl acetonato) (polystyrene supported ethylene diamino) coppeffll) complex

The m~xed complex was formed when polystyrene supported ethylene

d ~ a m ~ n e (P*NN) was refluxed w ~ t h copper(I1) acetyl acetonate (Scheme 6 8).

Scheme 6.8

Since ethylene diamlne is a neutral ligand, both acetyl acetone functions

should be present in the complex and this leads to a six-coordinate structure. In the

1R specbum of the wmplex, peaks characteristic of w-ordinated acetyl acetone are

present at 1590 cm" (vC=O) and 1410 cm" (vC-0) (Figure 6.12).

Figure 6.12. The 1R spectra of (a) p*NNC~(acac)~ and (b) P*NNCU(SB)~

The solid state electronic spectrum of the complex gives indication about a

pseudo octahedral stereochemistry Two well defined peaks are observed at

2 2 i 71 83 cm-' and 22232 cm' izhlch are due to dxy -+ dx'-y2 and dxz, dyz + dx -y

. . rransltions 7-he dz'->du--y- tratnsitlon due to its comparatively lower energy is not

observed in the U\'-VIS region (Figure 6.13) Four oxygen atoms of acetyl acetone

groups co-ord~nated to copper are equidistant but the two nitrogen atoms of

ethylene diamlne yroup are placed at some what larger distance wh~ch cause

dlstortlon of the octahedral structure

'0 OOA LI : zoo o , t i A- O&M/D/V~ n

WAVE LENGTH ( N M )

Figure 6.13. Electronic spectrum of P'NNCu(a~aca)~.

The complex ga\e anisotropic ESR spectrum even at room temperature due

ro the well separated rnetal centres in the polymer matrix The obtained parameters

a e g = 2 303. 2 =- 2 08. .A = 160, AL = 30 and a2 = 0.822. The ESR parameters

of cuprlc acetyl acetonate are y = 2 285, a - 2 04, A = 175 and AL = 77 5 4

Increase in the g balue of cupric acetyl acetonate on forming the mixed complex is

due to axial co-ord~nat~on Axial co-ordination distort the square planar

stereochemistry to pseudo octahedral '

6 2.9 (Aniline Schiffbase) (polystyrene supported ethylene diamino) copper(//) complex

Preparat~on i ~ t thls comple\ ln\ol\es the refluvlng of the polymer~c llgand

J ' * \ \ with copper Sch~tlbase (Scheme 6 9 )

Scheme 6.9

The complex should be SIX co-ord~nate s~nce ethylene dlamlne 1s a neutral

llgand The IR spectrum of the complex lndlcate the co-ord~nat~on of ethylene

dlarnrne functlon and Sch~ff base funct~on The characterlstlc peaks obta~ned are

1 140 crn ' (C-hi,\,) and 1620 crn ' v(C=N) (F~gure 6 12)

The electron~c spectrum of the complex contains peaks characteristic of

.l~stoned octahedral structure Peaks at 16920 c m ' and 25641 cm-I are ass~gned to

x + dx2-\' and dxz.. yz i dx2-y' transitions dz' -+ dx2-y2 transition occurs at a

lower frequency (F~gure 6 14)

+ / O O A I- 200.0 700 o fNM/ /v ) /ooo 0

WAVE LENGTH ( N M )

Figure 6.14. Electronic spectrum of P*NNCu(SBh

The obtiuned ESR parameters are g = 2 287, = 2 066, A, = 171 and

A1 = 30 g values are slrghtly higher on comparing the ESR spectrum of Cu(SB)z

Thrs vanation in g value IS accounted by axral bonding

The foregoing studies gave a reasonable account of the synthesrs and

characterrsat~on of a novel class of compounds, that is, the polymer supported

mixed llgand complexes A senes of mixed complexes were prepared by

employing suitably desrgned synthettc strategy and these complexes were

characterised structurally by IR, UV-VIS and ESR methods The structure and

stabilrty of these complexes were discussed based on these results

6.3 References

1 Kida, S., RUN. ('hem. Soc. Jpn., 29, 805 (1956)

2 h g e 's HandBook of ('hemistry (Ed., Dean, J . A ), McGraw Hill, New York, 1985

3 Nakamoto, K . Infrared and Raman Spectra of Inorgatzrc and Coordrnatlon ('omporrtds, J Wiley, New York, 1986

4 Kuska, H A and Rogers, M T , .I Chem Phys.., 43, 1744 (1965)

5 Slngh. R and Rao. V K N R , Polyhedron, 3, 137 ( 1 984)