Chapter IX

ANION COORDINATION CHEMISTRY

Although often overlooked in terms of their importance, anions are

ubiquitous in the natural world. Chloride anions are present in large

quantities in the oceans, nitrate and sulphate are present in acid rain and

carbonates are key constituents of biomineralized materials.

Anthropogenic anions, including pertechnetate, a radioactive product of

nuclear fuel reprocessing and phosphate and nitrates from agriculture and

other human activities, constitute major pollution hazards.

Anions are also critical to the maintenance of life. Transport or

transformation of anion is involved at some level in almost every

conceivable biochemical operation. It is essential in the formation of the

majority of enzyme - substrate and enzyme - cofactor complexes as well as

in the interaction between proteins and RNA or DNA, ATP,

phosphocreatine and other high-energy anionic phosphate derivatives are

at the centre of power processes as diverse and important as biosynthesis,

molecular transport and muscle contraction. They also serve as the energy

currency for a host of enzymatic transformations. Anion channels and

190

carnes are involved in the transport of small anions such as chloride,

phosphate and sulphate and thus serve to regulate the flux of key

metabolites into and out of cells while maintaining osmotic balance.

Anions are ubiquitous in biology. They are present in roughly 70%

of all enzymatic sites, play essential roles in many proteins, and are critical

for the manipulation and storage of genetic information. Anions are also

involved in regulating osmotic pressure, activating signal transduction

pathways, maintaining cell volume and in the production of electrical

signals. The disruption of anion flux across cell membranes is increasingly

recognized as being the primary deterrninentof many diseases, including

. f'b . 305 B 'cystic 1 roSlS, artter s syndrome,306 Dent's disease,30? Pendred's

syndrome308,309 and Osteropetrosis.310

Realisation of the significant role that anions play a vital role in

b· I . I 31110 oglca process, medicine,3!2 catalysis313 and environment314-316

evoked considerable interest in anion coordination chemistry. Recent

development in the area of anion recognition and sensing have produced a

variety of new selective receptors for anions.3!? The design of anion

receptors is particularly challenging when compared to the design of

receptors for cations. This is mainly because anions are larger than the

equivalent inter electronic cations3!8 and hence have a lower charge to

191

radius ratio. The more diffused nature of anions means that electrostatic

binding interactions are less effective than they would be for the

corresponding isoelectronic cations.

Unlike transition metal coordination, the binding of anions with

synthetic receptors fall into the realm of supramolecular chemistry ie.

interactions between molecular or ionic species in the absence of covalent

bond formation.312 Many researchers in the area of anion recognition

already refer to the field as anion coordination chemistry.356 We have

made a modest attempt to examine the influence of certain anions such as

chloride, bromide, nitrate and thiocyanate on thermal behavior ( chapter IX,

section A), crystal structure ( chapter IX, section B) and antimicrobial

activity ( chapter X).

192

Section A

SYNTHESIS, CHARACTERIZATION AND THERMAL STUDIES

OF LANTHANUM(III) COMPLEXES OF 2-(N-INDOLE-2-0NE)­

AMIN0-3-CARBOXYETHYL-4,5,6,7-TETRAHYDROBENZO[b]­

THIOPHENE CONTAINING DIFFERENT COUNTER ANIONS

This section is confined to the synthesis, characterization and

thermal studies of lanthanum(III) complexes of 2-(N-indole-2-one)amino-

3-carboxyethyl-4, 5, 6, 7-tetrahydrobenzo[b]thiophene (ISAT) containing

different counter anions, such as chloride, bromide, nitrate and

thiocyanate.

EXPERIMENTAL

Preparation of [La(ISAT)Cl3]

[La(ISAT)Cb] was prepared by refluxing an ethanolic solution of

lanthanum(III) chloride and ISAT (described in chapter IV).

193

Preparation of [La(ISAT)Br3l

Lanthanum(III) bromide was prepared from lanthanum oxide by

dissolving it in hydrobromic acid and crystallising the salt. The complex

[La(lSAT)Br3] was prepared by refluxing an ethanolic solution of

lanthanum(lII) bromide with an ethanolic solution of ISAT in 1:1 molar

ratio for about 10 h, pH was adjusted to 6.5 -7.0 and again refluxed for 6 h.

The resulting solution was concentrated and cooled. The solid mass thus

obtained was filtered and washed successively with ethanol and ether and

finally dried in vacuum.

Preparation of [La(ISAT)(N03h]

It was prepared from an ethanolic solution of ISAT and

lanthanum(III) nitrate solution (described in chapter IV).

Preparation of [La(ISAT)(NCSh]

Lanthanum(lII) cyanate was first prepared from lanthanum oxide

according to a reported method.319 For this lanthanum oxide was dissolved

in HN03 and evaporated to dryness. The dried mass was then dissolved in

ethanol and the hot ethanolic solution of lanthanum(III) nitrate was treated

194

-with excess of hot ethanolic potassium thiocyanate solution. The

precipitated KN03 was filtered off. Ethanolic solution of lanthanum(III)

thiocyanate thus formed was refluxed with an ethanolic solution of ISAT

in 1:1 molar ratio for 10h. pH was adjusted to 6.5 - 7.0 and again refluxed

for 6h. The resulting solution was concentrated and kept overnight. The

solid mass obtained was filtered and washed with ether and dried.

RESULTS AND DISCUSSION

As a consequence of the tridentate nature of the ligand,

lanthanum(III) forms 1: 1 species which can serve as a receptor for an anion

resulting in a coordination number of 9 for nitrate complex and six for

chloride, bromide and thiocyanate complexes. The complexes obtained was

analytically pure are listed in Table IX. 1. All the complexes are non-

hygroscopic and stable at room temperature and possess good keeping

qualities. Molar conductance values measured in DMSO adequately

confirmed the non-electrolytic nature of the complexes. Formulation of the

complexes has been done on the basis of their elemental analytical data,

molar conductance values and molecular mass determination by camphor

method. The molecular masses obtained were close to monomeric value.

·�,..._-.-.

Table IX. 1 Analytical data and molar conductance of the complexes

Analytical data Molar

(%) conductance in Complex DMSO

Metal C H N s Cl Br ohm-1 cm2 moF1

-

23.08 37.97 3.63 4.61 5.28 17.89 6.5

\0 [La(ISAT)Ch] - Ul

(23.18) (38.03) (3.67) (4.67) (5.33) (17.76)

[La(ISAT)Br3] 18.81 31.08 2.31 3.69 4.26 32.62

6.4 (31.12) (2.45) (4.36)

-

(32.71) (18.90) (3.82)

[La(ISAT)(NCS)3] 20.72 39.49 2.61 10.38 19.08

6.1 (10.49) (19.19)

-

(20.84) (39.58) (2.70)

La(ISAT){N03)3

20.36 33.21 2.60 10.03 4.69 6.3

(4.71) - -

(20.47) (33.51) (2.65) (10.31)

196

Infrared spectra

Infrared spectra of the metal complexes are closely similar among

themselves and the spectral data fit well for their structure (Table IX. 2).

The spectra of the ligand and complexes exhibit a strong band - 3170 cm-I

which is assignable to u(NH) of the indole ring of isatin moiety. The band

remains almost unaffected in the metal complexes indicating that NH of

isatin moiety is not involved in coordination. A strong band at

- 1730 cm-I in the ligand characteristic of u(C=O) of ester is shifted by

- 70 cm-1 to lower frequency upon complexation indicating coordination

of ester carbonyl with lanthanide ion. A strong band observed at 1650cm-1

in the ligand, corresponding to u(C=O) of isatin moiety is shifted downward

by - 40 cm-1 indicating the coordination of carbonyl oxygen with

lanthanide ion. A medium intensity band at 1596 cm-1 in the ligand due to

u(C=N) of azomethine is shifted to lower frequencies by - 25 cm-1 upon

complexation because of coordination of azomethine nitrogen with

lanthanum(III) ions.

Coordination by anions

Evidences for coordination by anions have also been obtained from

infrared spectral data. In the spectrum of the nitrate complex there are two

Table IX. 2 Important IR spectral bands of ISAT and its lanthanum(III) chloride,

bromide, thiocyanate and nitrate complexes

Compound U(NH) U(C=O) U(C=O)

U(C=N) U(Ln-N) U(Ln-0) ester ring

ISAT 3170 1730 1650 1596

[La(ISA T)Ch] 3172 1659 1614 1571 430 361

[La(ISAT)Br3 ] 3173 1662 1612 1572 425 365

[La(ISA T)(NCS)3 ] 3171 1661 1611 1573 427 366

[La(ISA T)(N03)3] 3174 1660 1610 1570 425 365

198

additional bands observed at 1473 cm-I

and 1246 cm- I. These bands are

assigned to the Vs and VI modes of the nitrate ion respectively. Since the

magnitude of the splitting of V3(N03) ie. (vs - vd is 227 cm- I it is concluded

that the nitrate ion is coordinated to the lanthanum ion in a bidentate

fashion.

The thiocyanate complex exhibits two bands at 2050 cm- I and

820 cm- I which are assigned to V(C-N) and v(C-S) modes of coordinated

thiocyanate which are not present in the spectrum of the ligand and the

spectra of other anionic complexes. Since V(C-N) mode of vibration is lower

than 2100 cm- I and v(C-S) vibration is greater than 774 cm-t, the

thiocyanate ion is coordinated to lanthanum ion through nitrogen in a

unidentate fashion. 319,320

The non-ligand bands appearing at 324 cm- I and 250 cm- I in the

chloro and bromo complexes are assignable to v(Ln-CI) and V (Ln-Br)

respectively.

Thermal studies

The study was focused on the TO curves of ISAt, [La(ISAT)Cb],

[La(ISAT)Br3J, [La(ISAT)(NCShJ and [La(ISAT)(N03)3J (Fig VII. 1,

VII. 4, IX. 1, IX. 2 and Fig IX. 3). Thermal features namely stability

199

9

,/

I "- /- - - - --I

I/

If

i7 J

/

I/

r-.. J/

00 \JJ

-S6 /

r/l/

r/l/

<t: _/

~5

4

2

100 200 300 400 500 600 700 BOO

TEMPERATURErC) --+

Fig IX. 1

[La(lSAT) Br3]

200

",-------.-I

//

II

7/-~

I

..."/ \ JI I

\ } \ I

i \ I I6 \

\ \ I

00 \ 1 I

..s I \ II \ I

CI) 5 .ICI)

\ /

~/

4

2

100 200 300 400 500 600 700 aoo

TEMPERATURE (0C) ~

Fig IX. 2

[La(ISAT)(NCS)3J

201

(DJ•

)1 t'/

f/ I

I (

I

I!

\I

II

lJI

i .....f

---00sU) IU)

« r:E I

/I r

ti.3;,iI,,

e )OC 2tO xc 4(0 5C'4 ~ 10;) ~

TEMPERATURE (0C) ~

Fig IX. 3

202

-11.

·13.

·13.

200 205 210 215 220 225

·12.

-13.

'l-< -13.

-14.9

.u.

-15.

·15.

1.36

11rx1ol

Fig IX. 4

[La(ISAT)Br3] - Stage 1

1.40 1.45 1.60

11rx10'

1.55

Fig IX. 5

1.110

[La(ISAT)Br3] - Stage 2

203

-11.

-12.

-12.

-13.

-13.

-14.

1.9 2.0 2.1 2.2 2.3 2.4

lffx!03

Fig IX. 6

[La(ISAT)(NCS)3] - Stage 1

·12.

·13.

·13.

·14.

·14. •

-15.lll-....--..--,--,.--.---.---.--.....--.-....--.

1.28 1.30 1.32 UI Ul 1.38 Ul 1.42

1trx10'

Fig IX. 7

[La(ISAT)(NCS)3] - Stage 2

204

11

-12

:13

·14 •

.11,

2..10 2.15 uo w 2.30 2.35 2AO 2A5

1/Tx1o'

Fig IX. 8

·12

} ,13

.14

•

• 15

,.- uo 1.55 uo I.OS 1,70 t.7$

11Tx1�

Fig IX. 9

[ La(ISAT)(N03h] - Stage 2

205

-18+------........ ---------

us 1.20 1.21 1.30

1/Tx 10'

Fig IX.10

[ La(ISAT)(N03)3] - Stage 3

Table IX. 3 Thermal decomposition data of [La(ISA T)Br3 ] and [La(ISA T)(NCS)3 ]

Decompo Temperature Peak Mass Cal. mass

Complex -sitionrange temperature loss loss Probable

assignment stage

(°

C) (°

C) % %

Loss of [La(ISAT)Br3 ] I 140 - 250 190 17.83 17.87 is a tin

moiety °'

II 300 - 610 450 63.12 63.15 Formation ofLa203

Loss of [La(ISA T)(NCS)3 ] I 140-250 200 19.54 19.64 is a tin

moiety Loss of

II 310- 610 475 44.73 44.52 anion and

formation of La203

Table IX. 4 Thermal decomposition data of [La(ISAT)(N03)3]

Decomposition Temperature Peak mass loss

Stage range temperature Probable assignment (°C) (°C) %

I 120-200 188 19.2 Loss of isatin moiety

II 220-430 428 33.81 Loss of benzothiophene moiety

m 480-620 619 24.13

Loss of anion and formation of La203

Table IX. 5

Complex

[La(ISAT)Br3 ]

[La(ISA T)(NCS)3 ]

Kinetic parameters for the thermal decomposition of [La(ISAT)Br3] and [La(ISAT)(NCS)3]

Deco mp-Energy of Entropy of Probable

Peak Order Correlation activation, Arrhenius activation, mechanism osition

temperature coefficient E factor, A LlS stage

(°C) (n) KJ/mol s-

'JK-1mor1

Random nucleation-

I 190 1 0.9949 89.95 6.8876x107

-91.12one nucleus

on each particle Random

00

nucleation-

II 480 1 0.9962 139.51 2.1776x108 -89.25one nucleus

on each particle Random

nucleation-

I 200 1 0.9945 61.12 2.6667x104 -137.72 one nucleus

on each particle Random

nucleation-

II 475 1 0.9909 229.35 7.8695xl013 17.23 one nucleus

on each p_article

Table IX. 6

Decomp- Peak osition temperature stage (°C)

I 188

II 428

m 619

Kinetic parameters for the thermal decomposition of [La(ISA T)(N03)3]

Order Correlation Energy of Arrhenius Entropy of Probable coefficient activation,E factor,A activation,�S mechanism

(n) KJ/mol s-1 JK.-1mor1

Random nucleation-

one N

1.85 0.9984 · 184.720.5372xl0 19 182.9835 nucleus on \0

each particle

Random nucleation-

1.6 0.9944 121.51 l.0002x107 -63.5332 Avrami equation II

Random nucleation-

one. 2.1 0.9956 274.14 3.3099x1015 99.5666 nucleus on

each p_article

210

ranges, peak temperature, mass loss data are presented in Tables VII. 2 ,

IX. 3 and Table IX. 4 and the kinetic parameters evaluated using

Coats - Redfern equation are given in Tables VII. 5, IX. 5 and Table IX. 6

and Fig IX. 5 and Fig IX. 6.

The ligand ISAT decomposed in two stages between 150 °C and

480 °C giving peak temperatures 211 °C and 382 °C respectively. The

first stage of decomposition/oxidation is assigned to the loss of isatin

moiety and the second stage is due to the remaining part of the compound.

In the lanthanum(III) complexes, nature of decomposition, peak

temperature, temperature ranges of decomposition are varied according to

the anion present . Thermal behaviour and kinetic parameters of

[La(ISA T)Cl3] are explained in Chapter VII.

Quite contrary to the decomposition pattern of [La(ISAT)Ch], the

decomposition of [La(ISAT)Br3] occurred in two distinct stages. The first

stage of decomposition started at 140 °C and was completed at 250 °C with

DTG peak at 190 °C. The mass loss corresponds to the removal of isatin

moiety from the complex. The second stage of decomposition has been

found to be in the wide range 300 - 610 °C, represented by a DTG peak at

480 °C. The mass loss registered in this stage corresponds to the removal of

remaining part of the ligand and bromine. The residual mass is in

211

agreement with the mass loss obtained by independent

pyrolysis experiment and the final decomposition product was analysed to

be La203 which is stable beyond this temperature.

The decomposition pattern of the complex [La(ISAT)(NCS)3]

is somewhat similar to the decomposition pattern of [La(ISAT)Br3].

The complex decomposed in two stages. The first stage of decomposition

is in the temperature range 140 - 250 °C with a DTG peak at 200 °C

and the second stage of decomposition occurs in the range 310 - 610 °C

with the DTG peak at 475 °C. The first stage is assigned to the loss of

isatin moiety and the second stage due to the loss of anion and the

formation of the residue La203 which is stable above this temperature.

The mass of the residue is in good agreement with the mass loss of

independent pyrolysis. Although the decomposition pattern of both

complexes are almost the same, a close examination of the

mass loss revealed that [La(ISAT)(NCS)3] decomposed at a

faster rate compared to [La(ISAT)Br3].

The decomposition pattern of [La(ISAT)(N03h] is similar

to [La(ISAT)Ch]. Both of them show three stages of decomposition. The

first stage of decomposition (120 - 200 °C) is attributed to the loss of

isatin moiety. The second and third stages of decomposition occur

in the

212

temperature ranges 220 - 430 °C and 480 - 620 °C. The second stage of

decomposition is due to the loss of benzothiophene moiety and the third

stage is due to the loss of anion and the formation of the residue La203• The

mass of the residue obtained is in agreement with the mass loss obtained in

independent pyrolysis experiment. Initial decomposition temperature of

metal complex has been often used to describe the thermal stability.303 On

the basis of this, the thermal stability follows the order:

[La(ISAT)Ch] > [La(ISAT)Br3] > [La(ISAT)(NCS)3] >

Decomposition kinetics and mechanism

The kinetic evaluation of the thermal decomposition of ISAT and its

chloro, bromo, thiocyanato and nitrato complexes were carried out using a

computer program. The activation energy of the decomposition reactions in

the range 61 -335 KJ mor1

which is comparable with that reported for

similar type of complexes. There is no definite trend in the values of

entropy of activation. The ligand, ISAT has negative value of entropy of

activation in both the stages. The complexes have negative and positive

entropy of activation. The negative value of the entropy of activation

213

indicates that the activated complex has a more ordered structure than the

reactants and that the reactions are slower than normal.

The thermal dissociation of the ligand and complexes seems to occur

through the same mechanism ie, the highest value of the correlation

coefficient for g(a) = -In (1-a), which is the random nucleation mechanism

with one nucleus on each particle. This represents the 'Mampel model'. But

the second stage of [La(ISAT)(N03)3] follows A vrami equation II.

Conclusion

From the thermal studies of the lanthanum(III) chloride, bromide,

thiocyanate and nitrate complexes of ISAT, it is concluded that the nature

of the decomposition changes with the anion, eventhough all the

complexes contain one ligand unit. The chloride and nitrate complexes

show three-stage decomposition and the others two-stage decomposition.

The chloride, bromide and thiocyanate are six coordinate complexes and

hence their thermal stability is more or less the same. But chloride complex

is more stable than bromide and thiocyanate complexes. It may be due to

the small size of the chloride ion and hence small strain at the central atom.

214

Section B

X-RAY DIFFRACTION STUDIES OF LANTHANUM(III)

COMPLEXES OF 2-(N-INDOLE-2-0NE)AMIN0-3-

CARBOXYETHYL- 4, 5, 6, 7-TETRAHYDROBENZO[b]­

THIOPHENE CONTAINING DIFFERENT COUNTER ANIONS

This section is devoted to the X-ray powder diffraction studies

of 2-(N-indole-2-one )amino-3-carboxyethyl-4,5,6, 7-tetrahydrobenzo[b ]-

thiophene and its lanthanum(III) complexes with the coordinating anions

chloride, bromide, nitrate and thiocyanate.

X-ray powder diffraction is a non-destructive technique widely

applied for the characterization of crystalline materials. The full power and

elegance of X-ray crystallography is perhaps most easily discerned in the

detailed elucidation of the crystalline structure and the atomic arrangements

of compounds which can be obtained and studied as individual single

crystals. However, many of the substances which come under examination

are obtainable only as aggregates of very small crystals. The production of

X-ray photography of such material and the use and interpretation of

321 324 b" f h" . powder diffraction patterns - form the su �ect matter o t 1s sect10n.

215

Copper X-ray tubes, for which the wavelength of the strongest

radiation (Ka) is approximately 1.5405 A are used for the X-ray diffraction

of the complexes. An approximately parallel beam of X-rays is directed at

the powdered specimen. Interaction of X-rays with sample creates

secondary diffracted beams of X-rays related to interplanar spacing in the

crystalline powder according to the mathematical relation 'Bragg's law'.

nA = 2d Sine

Where n is an integer, A is the wave length of the X-ray, d is the

interplanar spacing generating the diffraction and 8 is the diffraction angle.

The angle of diffraction (recorded as 28 by convention) is related to·

the interplanar spacing, d, by the Bragg law, and the intensity of the

diffraction maximum is related to the strength of these diffractions in the

specimen. The angles and intensities of diffractions are recorded

electronically using the detector. The Bragg angles and the set of

interplanar spacings have to be related to the unit cell parameters and

Miller indices assigned to the individual reflections.

216

EXPERIMENTAL

The ligand and its lanthanum complexes viz [La(ISAT)(N03)3],

[La(ISAT)Ch], [La(ISAT)Br3] and [La(ISAT)(NCS)3] were prepared

and their X-ray diffractograms were recorded, (Fig IX. 11 to Fig IX. 15).

RESULTS AND DISCUSSION

The diffractogram of ISAT exhibited 27 reflections between 28

ranging from 11 to 49 with maxima at 28 = 12.3835° corresponding to the

interplanar distance d= 7.1416A (Table IX. 7). The main peak have been

indexed by trial and error method. The Sin2 8 and d values were calculated.

The values are in good agreement with the observed values. The Sin28

values are in accordance with orthorhombic crystal system. The unit

cell dimensions are found to be a= 21.3661A, b = 15.7354A and

c = 14.4376A.

In the complex [La(ISAT)(N03)3], the X-ray diffraction pattern

displayed 12 reflections between 28 ranging from 11 to 58° with maxima

at 28 = 12.3832° which corresponds to interplanar distance, d = 7.1418A

(Table IX. 8). The main peaks have been indexed by using trial and error

method the Sin28 and 'd' values obtained have been compared with the'

217

Fig IX. 11

ISAT

218

Fig IX. 12

[La(ISAT)Ch]

219

Fig IX. 13

[La(ISAT)Br3]

220

Fig IX. 14

[La(ISAT)(N03)3]

221

Fig IX. 15

[La(ISAT)(NCS)3]

g \;

222

Table IX. 7 X-ray diffraction data of ISAT

NoObserved Relative Observed Calculated Calculated

dA intensity26

Sin2 6 Sin2 6 hIddA

1 7.9752 57.64 11.0849 0.0093 0.0096 020 7.9901

2 7.1416 100.00 12.3835 0.0116 0.0114 001 7.2188

3 6.4220 29.62 13.7776 0.0143 0.0138 011 6.5609

4 6.1525 20.02 14.3843 0.0156 0.0148 220 6.3342

5 5.7060 29.60 15.5165 0.0182. 0.0190 211 5.5896

6 5.3467 11.39 16.5663 0.0207 0.0208 400 5.3415

7 5.2264 6.10 16.9504 0.0216 0000216 030 5.2433

8 5.1145 5.88 17.3242 0.0226 0.0225 130 5.1350

9 4.6841 13.88 18.9300 0.0270 0.0268 032 4.7052

10 4.5178 2.16 19.6335 0.0290 0.0304 420 4.4191

11 4.0929 18.15 21.6953 0.0353 0.0349 510 4.1233

12 3.8593 15.56 23.0257 0.0398 0.0384 040 3.9318

13 3.7473 78.75 23.7237 0.0422 0.0418 421 3.7683

14 3.7061 15.82 23.9916 0.0431 0.0436 240 3.6889

15 3.4910 27.46 25.4939 0.0486 0.0480 012 3.5171

16 3.4341 20.64 25.9232 0.0502 0.0508 202 3.4187

17 3.3461 9.65 26.6174 0.0529 0.0538 431 3.3214

18 3.2230 49.85 27.6538 0.0571 0.0573 302 3.2187

19 3.1090 3.90 28.6891 0.0613 0.0615 341 3.1070

20 2.8986 5.48 30.8212 0.0706 0.0709 540 2.8935.21 2.8558 4.09 31.2957 0.0727 0.0724 232 2.8633

22 2.6651 2.06 33.5986 0.0835 0.0840 042 2.6578

23 .2.4577 2.69 36.5288 0.0982 0.0997 532 2.4098

24 2.1214 2.48 42.5798 0.1317 0.1294 233 2.1413

25 2.0705 3.16 43.6810 0.1383 0.1391 552 2.0655.

26 1.9232 2.09 47.2209 0.1604 0.1626 053 1.9103

27 1.8722 1.11 48.5875 0.1692 0.1678 253 1.8804

223

Table IX. 8 X-ray diffraction data of [La(ISAT)(N03hl

NoObserved Relative

2eObserved Calculated

hklCalculated

dA intensity Sin2 e Sin2 e dA

1 7.9613 2.36 11.1044 0.0093 0.0098 002 7.7881

2 7.1418 100.00 12.3832 0.0116 0.0116 100 7.1518

3 6.4443 1.56 13.7297 0.0143 0.0147 003 6.3552

4 6.1350 1.52 14.4255 0.0158 0.0165 101 5.9988

5 4.6564 3.49 19.0434 0.0274. 0.0281 111 4.5958

6 4.0772 3.15 21.7798 0.0356 0.0313 102 4.3542

7 3.7489 3.41 23.7138 0.0422 0.0411 103 3.7999

8 3,5633 4.93 24.9682 0.0467 0.0464 220 3.5759

9 2.9175 0.41 30.6167 0.0696 0.0629 211 3.0723

10 2.6624 0.21 37.6330 0.1040 0.1044 300 3.3839

11 1.7814 0.79 51.2400 0.1869 0.1856 400 1.7879

12 1.5966 0.19 57.6879 0.2327 0.2320 420 1.5993

224

calculated values. The Sin2e values are in agreement with the tetragonal

crystal lattice. The unit cell parameters were calculated. On the basis of

the above observations it can be concluded that the complex belongs to a

tetragonal crystal system with unit cell parameters a =b =7.152A and

c =10.9817A.

The X-ray diffraction pattern of [La(lSAT)Cl3J complex recorded

only one reflection having 2e = 27.0448° and the d spacing = 3.2942A

with relative intensity 100% showing amorphous nature. But the X-ray

diffraction pattern of [La(ISAT)Br3J complex showed 9 reflections

between 28 ranging from 11 to 28 with maxima at 28 = 23.7698° which

corresponds to the interplanar distance, d = 3.7401A (Table IX. 9). The

main peaks have been indexed by trial and error method. The Sin2e and the

corresponding d values were calculated. They are in excellent agreement

with the observed values. The Sin28 values are in agreement with the

tetragonal crystal system with unit cell dimensions a =b = 8.2247A and

c =14.8267A.

Similar to chloro complex, [La(lSAT)(NCS)3J showed only one

reflection in the X-ray diffractogram with 28 = 23.6612°, d spacing =

3.7571A and intensity =100%.

225

Table IX. 9 X-ray diffraction data of [La(ISAT)Br3]

No Observed Relative d A intensity

1 7.8940 25.46

2 7.0898 19.32

3 6.3822 10.92

4 4.7512 26.15

5 4.0704 23.70

6 3.7401 100.00

7 3.4271 28.35

8 3.3514 24.69

9 3.0910 16.26

29

11.1993

12.4745

13.8639

18.6602

21.8165

23.7698

25.9771

26.5749

28.8596

Observed Calculated Calculated Sin2 9 Sin2 9 hk1 d A

0.0095 0.0108 002 7.4138

0.0118 0.0117 100 7.1258

0.0145 0.0144 101 6.4187

0.0262 0.0261 111 4.7693

0.0358 0.0360 103 4.0603

0.0424 0 .. 0468 200 3.5610

0.0505 0.0495 201 3.4633

0.0528 0.0576 202 3.2093

0.0620 0.0666 114 2.9854

226

Conclusion . r

From the diffractograms of ISAT, [La(ISAT)(N03h],

[La(ISAT)Cl3], [La(ISAT)Br3] and [La(ISAT)(NCSh], it is concluded

that the ligand, ISAT is the most crystalline with orthorhombic crystal

system. During complex formation the crystallinity is decreased and the

crystal system is changed. [La(ISAT)(N03)3] and [La(ISAT)Br3] have

tetragonal crystal system while [La(ISAT)Cl3] and [La(ISAT)(NCS)3]

are amorphous.