C:J{5�PPE/l( -I I I

CHAPTER 111

IRON (111), MANGANESE (Ill) AND CHROMIUM (111) COMPLEXES OF

N, N°

- ETHYLENE - BIS (3 - CARBOXYPROPENAMIDE)

A survey of the literature showed that there have been numerous studies

on metal complexes with the derivatives of ethylenediamine53•84

•85

•133

•150

.

However, little information is available on transition metal complexes of the

derivative of this diamine with maleic anhydride. Except for the

synthesis of Co (II), Ni (II) and Pd (II) complexes of N, N'- ethylene­

bis (3 - carboxypropenamide) (EBCPH2) 167, no other studies on synthesis

and characterization of transition metal complexes of this ligand have been

carried out so far. It was therefore considered worthwhile to synthesize and

characterize some trivalent transition metal complexes with N, N'- ethylene -

bis (3 - carboxypropenamide).

Coordination chemistry of iron has great importance, because a large

number of iron complexes are biologically important. Hemoglobin, myoglobin,

cytochromes and ferredoxins employ iron (II) compounds, but the sidrophores

and transferrins are coordination compounds of iron (Ill). The reactivity of the

metal complexes is highly dependent on their structure and also on the

oxidation state of the metal. It has been established that iron (Ill) complexes of

ethylenediaminetetraacetic acid (edta) and other chelating agents are more

easily making iron physically accessible to the roots of the plants 261.

Because of the inherent theoretical interest and practical significance to

biochemistry, considerable efforts are being extended to the study of

complexes of iron (Ill). Similarly, manganese plays a very important role in

biological systems involving electron transfer reactions. Chromium also has a

number of biological roles for it, but the one that is most definite concerns

53

'glucose tolerance', which is a complex of chromium (Ill) with nicotinic acid and

amino acids; glycine, cysteine and glutamic acid2•

7.

Present . chapter deals with the preparation and characterization of

iron (Ill) chloride, bromide, thiocyanate, nitrate and perchlorate, and

manganese (Ill) acetate, chloride, bromide, thiocyanate, nitrate and

perchlorate, and chromium (111) chloride and thiocyanate complexes of amido

acid ligand, N, N' - ethylene - bis (3 - carboxypropenamide) (EBCPH2), which

is prepared by the condensation of ethylenediamine with maleic anhydride.

EXPERIMENTAL

The details of the starting materials and the purity of the reagents

employed are given in chapter II.

A. Preparation of iron (Ill) complexes with EBCPH2

1. Iron (Ill) chloride and bromide complexes

An aqueous methanolic solution of 0.01 mole sodium salt of the ligand

was added to 0.01 mole of ferric salt dissolved in methanol. The resulting

solution was stirred well. The brown precipitate formed was filtered, washed

several time with methanol and dried over P 4010.

2. Iron (Ill) nitrate complex

An aqueous methanolic solution of 0.01 mole sodium salt of the EBCPH2

was added to 0.01 mole of hot methanolic solution of iron (111) nitrate with

constant stirring. The brown precipitate formed was filtered, washed several

times with methanol and dried over P 4010.

3. Iron (Ill) thiocyanate complex

An ether solution of iron (Ill) thiocyanate (0.01 mole) was mixed with the

0.01 mole sodium salt solution of the EBCPH2 in aqueous methanol. The

resulting mixture was stirred well. A dark brown precipitate formed was filtered,

washed several times with ether and methanol and dried over P 4010.

54

4. Iron (Ill) perchlorate complex

An aqueous methanolic solution of 0.01 mole sodium salt of EBCPH2

was added to a methanolic solution of 0.01 mole iron (Ill) perchlorate. The

resulting solution was refluxed on a water bath for about half an hour-. The

reddish brown precipitate separated on concentration was filtered, washed

several times with methanol and dried over P 4010 .

8. Preparation of manganese (Ill) complexes with EBCPH2

1. Manganese (Ill) acetate complex

An aqueous methanolic solution of 0.01 mole sodium salt of the ligand,

EBCPH2 , was added to 0.01 mole of manganese (Ill) acetate dihydrate in

methanol. The resulting mixture was refluxed on a water bath for about one

hour. The brownish black precipitate formed was filtered, washed with

methanol and dried over P 4010.

2. Manganese (111) chloride, bromide, nitrate and perchlorate complexes

Preparation of manganese (Ill) chloride, bromide, nitrate and perchlorate

complexes were as follows. 0.01 mole of manganese (111) acetate dihydrate

was dissolved in methanol. To this 0.01 mole lithium chloride, bromide, nitrate

or perchlorate in methanol was added. To the resulting solution 0.01 mole

aqueous methanolic solution of the sodium salt of the ligand was added and

refluxed on a water bath for about one hour. On cooling a brownish black

solid separated. It was collected, washed repeatedly with methanol and dried

over P4010 .

3. Manganese (Ill) thiocyanate complex

0.01 mole of manganese (Ill) acetate di hydrate was dissolved in methanol

and 0.5g ammonium thiocyanate was added. To the resulting solution, 0.01

mole aqueous methanolic solution of the sodium salt of the ligand, EBCPH2,

was added and refluxed on a water bath for about two hours. On cooling a

55

brownish black solid separated. The complex thus separated was collected,

washed with methanol and dried over P 4010.

C. Preparation of chromium (Ill) complexes of EBCPH2

1. Chromium (111) Chloride complex

A solution of the metal salt (0.01 mole) was prepared in methanol. A

hot aqueous methanolic solution of the sodium salt of the ligand, EPCPH2

(0.01 mole) was added to this solution and refluxed for about two hours on a

water bath. The grey precipitate formed was filtered, washed with methanol

and dried over P 40 10.

2. Chromium (Ill) thiocyanate complex

0.01 mole of chromium (Ill) chloride was dissolved in methanol and 0.5g

of ammonium thiocyanate was added. To the resulting solution an aqueous

methanolic solution of the sodium salt of the ligand, EBCPH2 (0.01 mole), was

added and refluxed for about two hours on a water bath. The violet crystalline

precipitate formed was filtered, washed several times with methanol and dried

over P4010.

SOME GENERAL PROPERTIES OF THE COMOPLEXES

All the complexes are stable at room temperature and non-hygroscopic.

They are only slightly soluble in methanol and ethanol, insoluble in common

organic solvents like ether, acetone, benzene, carbon tetrachloride and

nitrobenzene but are freely soluble in DMF and DMSO. Dark brown or reddish

brown iron (Ill) complexes and grey coloured chromium (111) chloride

complexes of EBCPH2 were obtained as fine powder. All manganese (Ill)

complexes of EBCPH2 obtained are brownish black in colour. The

chromium (Ill) thiocyanate complex of EBCPH2 is violet in colour and is found

to be crystalline in nature.

56

ANALYSIS

Iron was estimated by direct pyrolysis of the complex to its oxide, Fe203.

For the estimation of chromium, the standard gra�imetric procedure described

by Vogel was employed254. Manganese was estimated by spectrophotometric

method as described in chapter 11. For the estimation of iron in perchlorate

complex, peaceful pyrolysis was employed 256. The chloride and bromide

were estimated by Volhard's method 254. Kurz's method was employed to

estimate perchlorate 255. The complexes were analysed for carbon, hydrogen

and nitrogen using a Heraeus-CHN-Rapid analyser. Sulphur in thiocyanate

complex was oxidised to sulphate and determined as barium sulphate254.

Details of the procedure are given in chapter II.

PHYSICAL MEASUREMENTS

The molar conductance values of the complexes in DMF, acetonitrile and

methanol were measured using Systronics direct reading type conductivity

meter. The magnetic susceptibilities were determined at room temperature by

Gouy method or on a Vibrating Sample Magnetometer (VSM) PAR model 155

at RSIC,· IIT, Madras. The infrared and electronic spectral studies, X-ray

powder diffraction, and thermal studies were carried out as described in

chapter II.

RESULTS AND DISCUSSION

The analytical data and empirical formulae of the complexes are

presented in Table 3.1. The data indicate that the complexes can be

represented as Fe(EBCP)X, Mn(EBCP)Y and Cr(EBCP)Z, where

X= Cl, Br, NCS, N03 or CI04, Y= Cl, Br, NCS, N03, CI04 or CH3COO and

Z = Cl or NCS.

Electrical conductance

The molar conductance values of the complexes in DMF, acetonitrile and

methanol using approximately 10-3 M solutions were determined at room

temperature. The results are given in Table 3.2. The molar conductance

57

values expected for 1:1 electrolytic behavior in DMF, acetonitrile and methanol

are 65-90, 120-170 and 80-115 ohm- l cm2 mor l respectively 262,263. All the

above complexes of iron (III), manganese (III) and chromium (III) are found to

behave as non-electrolytes in the solvents considered.

Infrared spectra

The important ir spectral bands of the free ligand, EBCPH2 and

its iron (III), chromium (III) and manganese (III) complexes are given in

Tables 3.3 and 3.4.

The ir spectrum of the free ligand, EBCPH2 , shows a strong band at

3300 cm-l and it is assigned to the NH stretching frequency of secondary

amide groups247, 264. The broad band at-3100 cm-l is assigned to the OH

stretching vibration of carboxylic acid groups. The low value of the OH

stretching vibration indicates the possibility of intramolecular hydrogen

bonding, with oxygen atom of the amide groups (-OH ...O=C<), in the

molecule246,265,266. A strong band observed at 1700 cm-l in the free ligand is

assigned to vas(C=O) of the carboxylic acid groups167, 248,249. Another strong

band at 1620 cm-1 in the spectra of the free ligand, assignable to V(c=O) of the

secondary amido' groups244, 250,267, remains almost unchanged in the

complexes, indicating non-participation in complexation.

Halide Complexes

In the iron (III), Chromium (III) and manganese (III) halide complexes of

EBCPH2 , the NH stretching frequency band is observed around

3230-3245 cm-l, indicating that coordination has occurred through nitrogen

atoms of both the amide groups 268,269. The strong band observed at1700 cm- l

in the ir spectrum of the free ligand, which is due to asymmetric CO of

carboxylic groups, disappears and two new bands at -1605 and - 1415 cm- l

are observed in the spectra of the complexes, which may be assigned to

asymmetric and symmetric stretching frequencies respectively of the

coordinated carboxylate groups270-273. The energy separation between the two

58

bands is -190 cm·1• The strong band observed at 1620 cm·1 in the ir spectrum

of the free ligand is assigned to stretching frequency of carbonyl group of

secondary amide. This band is noted almost at the same position in the ir

spectra of the complexes, indicating non-participation of amido oxygen in

coordination267. From the above observations it may be concluded that in

these complexes the ligand is tetradentate, coordination sites being the two

amido nitrogen and two oxygen atoms of carboxylate groups. The halide ions

are also coordinated to the metal ions as evidenced by the non-electrolytic

nature of the complexes.

The bands observed in the regions 565-585 cm·1 and 455 - 475 cm·1

in· the ir spectra of the complexes are assignable to VM-N and VM-o

respectively210, 214,21s .

Perchlorate complexes

Hathaway et al. have reported the ir spectral analysis of ionic and

coordinated perchlorate group276, 277. The perchlorate ion is a weakly

coordinating ligand. Rosenthal 27s has briefly reviewed the structure and

bonding in metal complexes containing this ion. In complexes, perchlorate can

0

I

I

I

I

Cl---.

//�

o

0 0

Fig (a)

O--M

Cl :-.. .._

//�

o

0 0

Fig (b)

0

,,/

0

�

cfyf'�O/M

Fig (c)

59

be present in the following three forms (1) ionic with tetrahedral symmetry, (2)

coordinated through one of the oxygen atoms as a monodentate ligand with

C3v symmetry and (3) coordinated through oxygen atoms to the metal ion as a

bidentate chelating ligand with C2v symmetry as shown in the figures a, b, and

c respectively.

The free perchlorate ion has a regular tetrahedral structure and belongs

to the point group Td, having nine vibrational degrees of freedom distributed

between four normal modes of vibrations v1, v2, v3 and v4. In general the triply

degenerate frequencies are observed around 1100 cm-1 (v3) and 625 cm-1 (v4).

The v3 appear as a very strong band with a poorly defined maximum, which is

occasionally split. The theoretically forbidden v1 mode usually appears as a

very weak band at - 930 cm-1. When the perchlorate ion is coordinated the

symmetry is lowered from Td to C3v or C2v depending on whether it acts as a

monodentate or bidentate ligand. The broad absorption peaks v3 and v4 split

and v1 becomes ir active 276' 279 "286.

In the perchlorato complexes of iron(III) and manganese(III) under study,

a strong band is observed near 111 O cm-1 and another around 1090 cm-1.

These are assigned to v4 and v1 of monodentate perchlorate group. Similarly,

two bands of medium intensity, occurring around 640 and 625 cm-1 are

attributed respectively to the v3 and v5 of coordinated CI04- group.

The weak band at 930 cm-1 in the case of iron(III) and the weak

band at 940cm·1 in the case of manganese(III) complexes can be assigned as

v2 of the coordinated perchlorate group. The vs vibrations expected

around 480 cm-1 for coordinated perchlorate could not be located

since the metal-ligand stretching frequency is also expected in this

region. The position of bands in the region 1150-1080 cm-1 and

700-620 cm·1 and the magnitude of separation between them suggest

the monodentate nature for the coordinated perchlorate group (C3v) in

these complexes. The conductance data is also in support of the

60

non-ionic nature of the perchlorate group and is therefore coordinated to

the metal ion.

Evidences are available from ir spectra of the perchlorate complexes to

show that the ligand, EBCPH2, is tetradentate. Strong bands near 3230 cm·1 in

the ir spectra of iron (Ill) and manganese (Ill) complexes indicate the

involvement of amide nitrogen in coordination. The characteristic vas (C=O) of

carboxylic group absorption at 1700 cm· 1 disappears and two strong bands,

one at 1600 cm· 1 and another at 1415 cm· 1 in the case of iron (Ill) and 1565

and 1385 cm·1 in the case of manganese (Ill) complexes, are observed.

These are assigned respectively to Vas (OCO) and vs (OCO) of coordinated

carboxylate groups. The strong band observed at 1620 cm·1 in the ir spectrum

of the ligand, assigned to vco of amide does not undergo significant shift in the

ir spectra of the complexes. Therefore it may be concluded that carbonyl

group of amide is not involved in coordination to the metal ion.

Nitrate Complexes

Addison et al. and Rosenthal have reported the ir spectral analyses of a

large number of nitrate complexes276-282

• 287

-289

. The free nitrate ion is planar

and belongs to D3h point group (I). The symmetric stretch (v1) of free nitrate

ion is usually ir inactive, but sometimes weakly active due to crystalline

interactions270. The out of plane deformation (v2), doubly degenerate stretch

(v3) and doubly degenerate inplane bending mode (v4) are the three ir active

modes of vibrations of nitrate ion. In general the doubly degenerate

0--M

(I) ( 11)

0 I\

( 111)

61

M M

(IV)

frequencies 1390 cm·1 (v3) and 720 cm·1 (v4) and out of plane 830 cm·1 (v2)

are observed in the spectra of ionic nitrates. The nitrate ion can coordinate to

metal as a unidentate (II), bidentate (Ill) or bridging (IV) ligand. Upon

coordination to a metal ion its effective symmetry is lowered from 03h to C2v in

all the three types of coordination. The nature of the nitrate ion in metal

complexes can be established by an examination of combination

band (v1 + v4) appearing in the region 1700-1800 cm·1, in the ir spectrum287.

Lever et al. suggested that compounds involving ionic nitrate exhibit a single

band in this region, while compounds containing coordinated nitrate exhibit

two bands287 . The degree of splitting of the two bands is generally larger for

bidentate than for monodentate groups, the usual range for the bidentate

being 20-60 cm·1 while for the monodentate nitrate group it is 5-25 cm·1.

Further, a combination of ionic and coordinated monodentate and bidentate

nitrate groups leads to three or more bands in this region. When the nitrate

ion is coordinated to a metal ion, v3 at 1390 cm· 1 splits into two bands, one at

1530-1480 cm·1 (v4) and the other at 1290-1250 cm·1

(v1). The v2 due to N-0

stretch, which is usually ir inactive in the free nitrate ion also appears around

1050 cm·1. The non-planer rocking frequency v6 occurs around

800 cm·1 286•290 . It is difficult to establish the monodentate or bidentate nature

of the nitrate group from ir studies, since in both cases the symmetry is

lowered to C2v, The magnitude of separations between v4 and v1 is often

62

considered to assign the nature of nitrate group. A separation of 100-150 cm·1

(flv) indicates the monodentate nitrate group while a separation of about

200 cm·1 indicates the bidentate and bridging nature of nitrate group in

complexes 2s1,291-291.

The ir spectra of iron (111) and manganese (111) nitrate complexes of

EBCPH2 show bands assignable to the coordinated nitrate group. Strong band

present at 1385 cm·1 and medium intensity bands at -1450 cm·1 for the

complexes are assignable to the split components of v3. Magnitude of

separations suggests monodentate nature of N03 group. The nitrato

complexes of iron (Ill) and manganese (Ill) also show two weak bands in the

region 1700-1800 cm·1. They can be attributed to the combination band. The

peak observed at - 840 cm·1 is assigned to non-planer rocking (v5) vibrations.

Evidences are available from ir spectra of the nitrato complexes to show

that the ligand in this case also behaves as tetradentate. The strong band

at -3245 cm·1 in the ir spectra of iron (Ill) and manganese (Ill) complexes

indicate the participation of amide nitrogen in complexation. The character­

istic carboxylic group absorption at 1700 cm· 1 disappears and two strong

bands, one at 1605 and another at 1420 cm·1 in the case of iron (Ill) and 1585

and 1405 cm·1 in the case of manganese (Ill) complexes, are observed.

These are assigned respectively to Vas (OCO) and vs (OCO) of coordinated

carboxylate groups. The strong band observed at 1620 cm·1 in the ir spectra

of the ligand is assigned to vco of the amide. This band is noted almost at the

same position in the spectra of the complexes, indicating non-participation of

amide oxygen in coordination. The bands observed at -570 and -465 cm·1

are assigned to VM-N and YM-o respectively.

Acetate Complex

The acetate ion may be coordinated to the metal ion in the following

manner.

63

/0 M

�/0� CH

3c� CH

3C /

�'a/ "\o

·. (I) (II)

�)---M

CH3---C /

�' 0

---M

( 111)

The acetate ion itself. has low symmetry. Therefore further decrease in

symmetry will not be located on complex formation. Only slight changes in the

spectrum are observed in the case of acetate complexes. The Vas (OCO") and

vs (OCO") of the free acetate ion are observed at around 1565 and

1415 cm·1 respectively 298. For the unidentate carboxylate group, one of the

C - 0 bonds will have enhanced double bond character and usually observed

at high frequency region 1590-1650 cm· 1 299. Consequently the separation

between the two V(c-oi is much larger in monodentate complexes than in free

ion. In the bidentate chelate complexes the opposite is observed and

separation becomes smaller than that of the free ion. But in bridging

complexes, the two vc=o are close to the free ion frequencies 300•302.

In the present investigation, the nature of the acetate group in the

manganese (Ill) acetate complex of EBCPH2 cannot be predicted from the ir

spectrum because there are ligand vibrations in the same region where

64

carbonyl group vibrations are also expected. However, the coordinated nature

of the acetate ion is evidenced from the conductance measurements.

Thiocyanate Complexes

The ir spectral studies on the complexes carrying NCS group

have been reported by Mitchell and Williams, Lewis et al. and

Chatt Duncanson et al. 303"305. The thiocyanate ion can function as an

am.bidentate ligand that may coordinate to the metal through nitrogen (M-NCS)

or sulphur (M-SCN). It can also form bridge between two metal ions 270 • 306.

Sabatini and Bertini have given procedures for identifying the coordination

sites by ir spectral analysis 307.

M ---- NCS ----M

The thiocyanate ion can have the following canonical structures308.

N =c-s· -N = C-S 2 ·N-C=S +

(I) (II) ( 111)

In the complexes of the type M-NCS, the structures II and Ill will

contribute more. Whereas in M-SCN, the structure I predominates.

Consequently in M-NCS complexes the frequency of C-N stretch is lowered

while that of the C-S stretch is raised. In M-SCN complexes the reverse is

true. Attempts have been made to establish the nature of the coordination of

the thiocyanate group from the C-N stretch frequency, since no ligand bands

are generally expected in this region303"

309. However, the shift of C-N stretch in

the region 2150 -2050 cm· 1 is rather uncertain and makes it difficult to

ascertain the nature of the bonding. On the other hand, the C-S stretch has

been in the range 860 -780 cm·1 in M-NCS and around 700 cm· 1 in M-SCN

complexes. When the bonding is through nitrogen, the NCS deformation

vibration occurs as a single band around 490 - 460 cm·1, while sulphur

coordination gives a band in the region 400 - 445 cm·1 304•310•3 13.

65

In the ir spectra of iron(III), chromium(III) and manganese(III) thiocyanate

complexes of EBCPH2 , very strong band is observed at 2060, 2090 and

2065cm-1 respectively. This band is assignable to vc-N of thiocyanate group.

The C-S stretch could not be identified since the ligand itself has bands in that

region. Hence the NCS bending vibration is used for ascertaining the

coordination site307. The medium peak observed at 490, 480 and 485 cm-

1 in

iron (Ill), chromium (111) and manganese (Ill) thiocyanate complexes

respectively are assignable to the NCS bending vibration. The values show

that thiocyanate group is coordinated through nitrogen. The conductance data

also reveal the non-ionic nature of the thiocyanate group.

Evidences are available from ir spectra of the thiocyanate complexes to

show that the ligand is tetradentate. Strong bands near 3240 cm· 1 in the

spectra of iron (Ill), chromium (Ill) and manganese (Ill) complexes indicate the

involvement of amido nitrogen in coordination. The Vas (OCO) and vs (OCO) of

coordinated carboxylate groups are observed at -1600and -1410 cm- 1

respectively in these complexes. The energy separation between the bands

11v (OCO) is -190 cm-1. The strong band at 1620 cm· 1 in the ir spectrum of the

ligand is assigned to stretching vibration of C=O of amide. This band is noted

almost at the same position in the thiocyanate complexes indicating non­

involvement of amido oxygen in coordination.

Magnetic behaviour

The magnetic susceptibilities, the diamagnetic corrections and the

effective magnetic moments of the iron (Ill), chromium (Ill) and

manganese (Ill) complexes of EBCPH2 are presented in Table 3.5.

Iron (Ill) complexes

The magnetic studies of iron (Ill) complexes revealed interesting results.

Iron (Ill) complexes with the following magnetic behaviours have been

discussed. (a) High spin complexes (b) Low-spin complexes (c) Complexes

with antiferromagnetic interactions (d) Complexes with high-spin-low-spin

66

equilibrium and (e) Complexes with three unpaired spins i.e., complexes with a

quartet ground state.

High spin complexes of iron (III) are formed with weak or moderately

stron'g ligands 314,315. The ground state term, 6S of free Fe+3 ion is not split by

the presence of any ligand field. Therefore the magnetic moments of high ­(

spin complexes are found to be very clo$~ to the spin only value 5.92 BM. The,',

low-spin complexes of iron (III) with 2T29 ground state have considerable orbital

configuration and a value 2.3 8M is expected. This value is considerably

higher than the spin only value 316,317.

Complexes with antiferromagnetic interactions result when there is a

possibility of bridging between two metal atoms in a complex. This can occur

in two ways, either by direct metal-metal interactions or by interactions via

bridging atom. The lowering of magnetic moments in complexes can be due

to high-spin-Iow-spin equilibrium or due to the presence of a quartet ground

state (4G) for the free ion349-351. For example in iron (III) trisdithiocarbamato

complexes spin equilibrium has been observed between spin state S=3/2 and

8=1/2. Where the ligand field is such that the two states are close by in

energy, both the states will be populated and the system will be a mixture of

two forms 318,319. At low temperatures the complex tends to become fully

low-spin and at high temperature a completely high-spin behaviour is

established.

Several iron (III) complexes showing this type of magnetic behaviour,

studied at different temperatures, are also known. A few monohalogeno­

bis (dithiocarbamato) iron (III) complexes are reported to show a magnetic

moment of about 4 8M which is very close to the spin only value of 3.87 8M

calculated for three unpaired electrons. This indicates a quartet ground

state (4G) for the metal ion in the complexes 349-351.

In the present complexes, the magnetic moments of [Fe(E8CP)X]

(X = CI, Br, NCS, N03 or CI04) are in the range 3.77 - 4.66 8M. The lower

value of magnetic moments indicates the presence of metal-metal interactions,

67

as reported earlier in many five coordinate high-spin complexes320-325

.

However, to ascertain the nature of magnetic behaviour it is worthwhile to

carry out the magnetic measurements at different temperatures. Such an

investigation could not be carried out due to lack of facilities.

Chromium {Ill) Complexes

The magnetic properties of octahedral chromium (Ill) complexes are

uncomplicated. All such complexes contain three unpaired electrons

irrespective of the strength of ligand field and this has been confirmed for all

known molecular complexes326. A more sophisticated theory further predicts

that the magnetic moment should be very close to, but slightly below, the spin

only value, 3.88 BM. This too has been observed experimentally. The

magnetic moment values observed for the chromium (Ill) complexes of

EBCPH2 (Table 3.5) correspond to three unpaired electrons. The magnetic

moments of [Cr(EBCP)NCS] (3.76 BM) is slightly less than the spin only value

as is generally the case with octahedral chromium (Ill) complexes due to very

small spin-orbit coupling constant of cr+3 327-329.

Manganese {Ill) Complexes

Manganese (Ill) with electronic configuration d4 can have either four

unpaired electrons or two unpaired electrons in its octahedral complexes.

Majority of manganese (Ill) complexes known are octahedral and high-spin.

The low-spin manganese (Ill) complexes are limited in number and are

observed only in some cyano complexes so far. The spin only value expected

for a high-spin manganese (Ill) complex is 4.9 BM 330.

The magnetic moments of [Mn(EBCP)Y] (Y = Cl, Br, NCS, N03, CI04 or

CH3COO) are in the range 4.80-4.95 BM. This value is very close to the

magnetic moment value for high-spin manganese (Ill) complexes (4.90 BM).

The slight deviation from the expected value may be due to metal-metal

interaction, as reported earlier in many five coordinate complexes 331-333.

68

Electronic Spectra

The electronic spectral bands of the complexes in DMF solution and their

probable assignments are given in Tables 3.6, 3.7 and 3.8.

In an octahedral environment the ground state is 6A19 for Fe(III). As no

other sextet state present, all the transitions are spin-forbidden 334. Because

of the greater tendency of the trivalent ion to have charge transfer bands in the

near ultra violet region, which have strong low energy wings in the visible

region, the very weak spin forbidden d-d bands are completely obscured.

In the present iron (Ill) complexes the bands observed with maxima

33330, 27780 and 26315 cm·1 are attributed to charge transfer. A

comparatively weak broad band with maximum at -20,000 is assigned to spin

forbidden transition 6A197 4T19 of octahedral iron (Ill) complex333• 335

-337

_

The chromium (Ill) ion has the ground state 4F derived from the d3

configuration, which splits into 4A29, 4T29 and 4T19 in an octahedral field.

Among the three states 4A29 state lies lowest in energy. Electronic transition to

4T19(P) must also be considered. The expected spin allowed d-d transitions

are 4A297 4T29, 4A297 4

T19(F) and 4A2974T19 (P). The 4A2974T19(P) transition

is often obscured by charge transfer or ligand transitions.

In the present chromium (Ill) complexes, bands observed at -33170 and

26660 cm·1 are due to charge transfer. The4A297 4T19(P) transition is most

probably obscured by the charge transfer band maxima at 26660 cm·1. The

weak bands with maxima appearing at 21670 cm·1 and at around 15500 cm·1,

for the halide complex, [Cr(EBCP)CI], are assigned to the 4A2974T19(F) and

4A2974T29(F) transitions respectively. The broad band with maximum at

17575 cm·1 in the thiocyanate complex [Cr(EBCP)NCS] is assigned to the 4A2974T19(F) transition. The 4A2974T29(F) transition in this case may be

overlapped by 4A2974T19(F) 338,339

.

The manganese (111) ion has the ground state 50 derived form d4

configuration, which in an octahedral field splits into 5E9 and 5T 29. These are

69

the only quintet state present and hence only one d-d transition, sE9 7 sT29, is

expected for manganese (Ill) complexes. However, high-spin octahedral

manganese (Ill) complexes are susceptible to Jahn-Teller distortion. Hence,

more than one transition involving the split components of sE9 and sT 29 in low

symmetry can also occur340-343

. Usually, the electronic spectra of

manganese (Ill) complexes show two or three bands in the visible region.

The electronic spectra of manganese (Ill) complexes show two medium

intensity broad bands with maxima at 33,330; 27,550 cm· 1 and a broad band

with maxima at 19850 cm·1. Of these first two bands can be assigned to

charge transfer and the third one to sE9 7 sT29 transitions. The thiocyanate

complex of manganese (Ill) shows an additional shoulder band at

-18350 cm·1. This absorption may be due to the electronic transition between

the split components of the sr 29 and sE9 levels of the distorted octahedral

complex.

X-ray powder diffraction study of [Fe (EBCP) Cl]

The x-ray powder pattern of the Fe (Ill) complex, Fig.3.4, was taken on a

Rigaku, Japan or Philips PW 1710 x-ray powder diffractometer on chart

recorder. A sample spinner was used to remove the effect of orientation of the

powder sample. Reflections from various sets of planes have been recorded

for 5° to 70° at a sample rotation 0.05°/sec with CoKa (A=1.7902 A) radiation

using 40 KV 20MA. The attempts to index the lines on the XRD powder

pattern for cubic and tetragonal system failed. But all the 41 lines, by

employing Hesse and Lipson's procedure344"346

, could be indexed successfully

for the orthorhombic system. The density of the complex was determined with

specific gravity bottle using petroleum ether as the displacing liquid. The

observed and calculated sin28 values, (hkl) values and relative intensity are

listed in Table.3.9.

The sin28 difference value 0.0104, occurring eleven times in the sin28

difference chart, was taken as the reflection from (200) plane. Then the value

70

for sin28(1oo) will be 0.0026, which occurs four times in the sin28 difference

chart. The higher order reflection (300) is also present in the experimental

sin28 values. The value, 0.0144 occurring twelve times in the chart was

chosen as reflection from (020) plane. Then the value 0.0036, which occurs

five times in the sin28 difference chart, was taken as the reflection from (010)

plane. This line and its higher order reflections are also present in the

experimental sin28 values. The value 0.0056, which occurs five times in the

chart was taken as the reflection from (001) plane. Reflection from this plane

is not present in the observed sin28 values. However, its higher order

reflection (005) is present in the observed sin28 values. Using lattice

constants, A= 0.0026, B = 0.0036 and C = 0.0056, the unit cell dimensions for

the orthorhombic system, were calculated using the relation,

Sin28(hkll = A h2 + B k2 + C 12

l2 where A=-,

4a2

').} ').} B=- and C=-

4b2

4c2

By substituting, the values of sin28(1oo), sin28(010) and sin28(001), the unit

cell dimensions a, b and c for the sample were obtained, the values being

a= 17.5544A, b = 14.9184A and c = 11.9613A. So the unit cell volume

V = 3.132X10"21cm3. The density of the complex, d = 0.7207g/cm3 and its

molecular mass is 345. The number of molecules per unit cell was calculated

using the formula.

dNoV n=--

0.72707x6.023xl023

x3.132x10-2 1

n=----�------ = 3.94::::: 4 345

The presence of four molecules for unit cell confirms the correctness of

our assumption. The diffraction pattern of Cr (111) and Mn (Il l) complexes

showed only very few lines of weak intensity, so the pattern could not be

analysed.

71

SUMMARY

Complexes of iron (Ill), chromium (Ill) and manganese (Ill) with

compositions [ Fe(EBCP)X ] (X = Cl, Br, NCS, N03 or CI04), [ Mn(EBCP)Y ]

(Y = Cl, Br, NCS, N03, CI04 or CH3COO) and [ Cr(EBCP)Z ] (Z = Cl or NCS)

have been prepared and their physicochemical properties studied. All the

complexes are microcrystalline powder in high yield, stable and non­

hygroscopic at room temperature.

The molar conductance values in DMF, acetonitrile and methanol show

that all the thirteen complexes are non-electrolytes. The ir spectra of

[Fe(EBCP)N03] and [Mn(EBCP)N03] show a strong band at 1385 cm- 1 and a

medium intensity band at -1450 cm·1 indicating monodentate behaviour of the

nitrate group. In the case of thiocyanate complexes the NCS deformation

vibration is observed at around 485 cm·1 with medium intensity. Therefore, it is

concluded that in the nitrate and thiocyanate complexes the anion is

coordinated through nitrogen atom. In the ir spectra of the perchlorate

complexes of Fe(III) and Mn(III) the characteristic bands of monodentate

perchlorate group are observed around 111 O cm·1, 1090 cm·1

, 640 cm·1 and

625 cm·1. Infrared spectra of complexes show that EBCPH2 behaves as a

divalent tetradentate ligand coordinating through two-amido nitrogen and two

oxygen atoms of the carboxylate groups. The magnetic moment values

suggest that all the complexes are high-spin type. The lower value of magnetic

moment obtained for the complexes of Fe (Ill) (3.77-4.66 BM) and Cr (Ill)

(3.76-3.85 BM) suggest antiferromagnetic interaction in these complexes.

From the electronic spectral data it is concluded that all the three metal ions

have distorted octahedral or octahedral environment. The Fe (Ill) and Cr (Ill)

complexes are likely to have a dimeric structure. The six coordination is

ach.ieved by the interaction with electron rich centers of adjacent molecule.

The value of µett (4.80 - 4.95 BM) for the [Mn(EBCP)Y] indicates the high­

spin nature of the complexes. The slight deviation from the expected value

(4.90 BM) may be due to metal-metal interaction, as reported earlier for many

72

five coordinate complexes. The broad and strong electronic spectral bands

and practically the same magnetic moments suggest similar square pyramidal

geometry with C4v symmetry for all the Mn (Ill) complexes.

X - ray powder diffraction study of a typical sample, [Fe (EBCP) Cl], was

also done to ascertain the crystalline nature and to determine the unit cell

parameters. It is found to be orthorhombic with the unit cell dimensions,

a= 17.5544 A, b = 14.9184Aand c = 11.9613A.

Analytical, spectral and magnetic studies suggest that the possible

structures of the complexes are as given in the next three pages

X

0 0 � /

HN - CH2

CH2

- NH" �

/C � -/ C

CH �F

_'\CH

II / �� II X= Cl, Br, NCS, N0

3or Cl0

4

CH CH

"' I /

C I

� O I o

C

� 0 0

0� �� � �

C O 0- C

/ � I/ "'

CH �:

CH

CH � CH

\ � c// "HN-CH CH-NH/�

Fig.3.1 0 2 2

0

X

-.J \.;.J

Fig.3.2

y

0 0

� /HN -CH2

CH2

-NH" �/c c ,

� /� )H

�c o o c�

0 0

Y = Cl, Br, NCS, N03

, CI04

or CH3COO

-..J

�

z

� /HN -CH2

CH2

-NH" /0

t

0

/C "' / C

:H �I/ I Cr - Z = Cl or NCS

� /i� )

H

�c o I o c�o� o� �o

/o

�C O I 0-C

Fig. 3.3

/ � I/ "' CH

�: CH

II/-c\ �

c

/cH

,// "HN-CH CH-NH/�6/" 2 2

0

z

-...J V,

Table 3.1 Some physical and analytical data of EBCPH2 and its Fe(III), Cr(III) and Mn(III) complexes SI. Empirical Colour Found �alculated} %No. Formula M C N Cl7Br S7CI04

1 C10H12N206 [EBCPH2] White - 47.12 4.54 10.78

(46.87) (4.69) (10.94)

2 Fe(EBCP)CI Deep 16.02 34.28 2.81 8.18 9.97

brown (16.17) (34.75) (2.90) (8.11) (10.27)

3 Fe(EBCP)Br Dark 13.88 31.15 2.32 7.1 20.84

brown (14.33) (30.79) (2.57) (7.18) (20.50) 0\

4 Fe(EBCP)NCS Reddish 14.87 35.56 2.63 11.75 - 8.84

brown (15.18) (35.88) (2.72) (11.42) - (8.70)

5 Fe(EBCP)N03 Brown 14.76 32.63 (2.52) 11.02

(15.02) (32.27) (2.69) (11.29)

6 Fe(EBCP)Cl04 Reddish 13.88 29.14 2.36 6.75 - 24.49

brown (13.65) (29.32) (2.44) (6.84) - (24.30)

7 Cr(EBCP)CI Grey 15.99 35.28 2.74 8.38 10.45

(15.23) (35.14) (2.93) (8.20) (10.38)

8 Cr(EBCP)NCS Violet 14.38 36.43 2.66 11.71 - 8.55

(14.29) (36.26) (2. 75) (11.54) - (8.79)

Table 3.1 {contd .... }

SI. Empirical Colour Found (calculated}%

No. formula M C H N Cl/Br S/CI04

9 Mn(EBCP)CI Brownish 16.15 34.58 2.73 8.25 10.53

black (15.95) (34.84) (2.90) (8.13) (10.29)

10 Mn(EBCP)Br Brownish 14.42 30.56 2.45 7.51 20.26

black (14.13) (30.86) (2.57) (7.20) (20.55)

11 Mn(EBCP)NCS Brownish 14.82 35.73 2.91 11.09 - 8.91

black (14.97) (35.97) (2.73) (11.45) - (8.72)

12 Mn(EBCP)N03 Brownish 15.10 32.06 2.57 11.52

black (14.81) (32.35) (2.70) (11.32)

13 Mn(EBCP)CI04 Brownish 13.23 29.54 2.61 6.93 - 24.84

black (13.45) (29.38) (2.45) (6.86) - (24.35)

14 Mn(EBCP)CH3COO Brownish 15.25 38.87 3.45 7.83

black (14.93) (39.14) (3.53) (7.61)

Table 3.2 Molar conductance values of Fe(III), Cr(III) and Mn(III) complexes of EBCP}i

Dimeth�I formamide Acetonitrile Methanol

SI. Complex Concn� Molar Concn� Molar Concn. Molar Assignment No. x1f

f3M Conductance* x1 ff3M Conductance* x1 f

f3M Conductance*

1 [Fe(EBCP)CI] 1.02 14.6 1.11 20.8 1.09 19.1 non-electrolyte

2 [Fe(EBCP)Br] 1.05 24.7 0.96 26.0 1.00 25.7 non-electrolyte

3 [Fe(EBCP) NCS] 1.06 16.2 0.99 30.4 1.23 14.6 non-electrolyte

4 [Fe(EBCP)N03] 1.03 27.8 1.06 37.3 1.10 35.7 non-electrolyte

5 [Fe(EBCP)CI04] 0.97 20.8 1.04 21.5 1.01 27.6 non-electrolyte

6 [Cr(EBCP)CI] 1.12 8.9 1.24 12.7 1.22 14.3 non-electrolyte

7 [Cr(EBCP)NCS] 1.07 12.9 1.14 20.5 1.01 20.9 non-electrolyte

8 [Mn(EBCP)CI] 1.09 18.5 1.10 22.4 1.07 23.2 non-electrolyte

9 [Mn(EBCP)Br] 1.07 22.1 1.02 26.4 0.98 21.6 non-electrolyte

10 [Mn(EBCP)NCS] 1.05 16.5 1.13 28.0 1.11 23.9 non-electrolyte

11 [Mn(EBCP)N03] 0.99 21.7 1.05 36.4 1.07 32.9 non-electrolyte

12 [Mn(EBCP)CI04] 1.03 16.2 1.00 17.4 1.06 29.7 non-electrolyte

13 [Mn(EBCP)CH3COO] 1.17 10.3 1.01 21.9 1.13 25.0 non-electrolyte

*Ohm·1 cm2 mor1

Table 3.3 Infrared spectral bands (cm-1) of EBCPH2(L

1 H2) and its Fe(III) and Cr(III) complexes

EBCPH2(L 1 H2) [Fel I Cl] [Fel I Br] [Fel I NCS] [Fel I N03] [Fel

I CI04] [Crl I Cl]

3300(s) 3230(s) 3245(s) 3240(s) 3243(s) 3230(s) 3235(s)

31 OO(w)

2435(w) 2435(w) 2435(w) 2435(w) 2435(w) 2435(w) 2435(w)

2353(w) 2355(w) 2355(w) 2355(w) 2355(w) 2355(w) 2355(w)

2065(s)

1860(w) 1860(w) 1860(w) 1860(w) 1860(w) 1860(w) 1860(w) 1775(w)

1760(w)

1700(s)

1620(s) 1624(s) 1623(s) 1624(s) 1625(s) 1625(s) 1624(s)

1605(s) 1605(s) 1595(s) 1605(s) 1600(s) 1605(s)

1560(s) 1550(w) 1550(w) 1540(w) 1540(w) 1540(w) 1555(w) 1450(m)

1413(s) 1415(s) 141 O(s) 1420(s) 1415(s) 1420(s)

1385(s)

1375(s) 131 S(s) 1320(s) 131 S(s) 1315(w) 1320(s) 131 S(s)

1220(w) 1215(w) 1215(w) 1215(w) 1215(w) 1220(vw) 1215(w)

[Crl I NCS] Tentative Assignments

3245(s) VNH of sec.amide

voH of the carboxylic acid

2435(w)

2355(w) 2090(s) vc-N (Thiocyanate)

1860(w) v1 +v4 NQ3 coordinated

vc=o of carboxylic acid

1624(s) vco of amide I band

1600(s) vco asym. of coordinated

carboxylate group

1555(w) VNH inplane amide 11 band v 4 N03 coordinated

141 O(w)) vco sym. of coordinated

carboxylate group v1 N03 coordinated

1320(m) VCN + NH bending

amide Ill, combination band

1215(sh)

'°

· Table 3.3 {Contd ...... )

EBCPH2(L 1 H2) [FeL

1CI] [FeL

1Br] [FeL

1NCS] [FeL1 NOs] [FeL

1 Cl04] [CrL 1CI] [CrL

1NCS] Tentative Assignments

111 O(s) v4 CI04 coordinated

1090(m) v 1 Cl04 coordinated

1060(w) 1060(w) 1060(w) 1060(w) 1060(w) 1060(w) 1065(w) 1055(w)

1045(m) v2 N03 coordinated

1005(m) 990(m) 1000(m) 990(w) 990(w) 1 OOO(w) 985(w) 990(w)

950(w) 950(w) 950(w) 950(w) 950(w) 950(w) 955(w) 950(w)

930(w) v2 C104 coordinated

860(w) 860(w) 860(w) 860(w) 860(w) 860(w) 860(w) 860(w)

840(s) v6 rocking of N03

785(w) 785(w) 785(w) 785(w) 785(w) 785(w) 785(w)

685(w) 685(w) 690(w) 685(w) 695(w) 685(w) 690(w)

640(m) v3 CI04 coordinated

625(m) v5 CI04 coordinated

565(w) 570(m) 570(m) 570(w) 570(w) 580(w) 595(w) VM-N

520(w) 520(w) 525(w) 520(w) 525(w) 520(w) 520(w) 520(w)

490(m) 480(m) NCS deformation

455(w) 460(w) 455(w) 460(m) 450(w) 460(w) 470(w) VM-0

s=strong, vs=very strong, m = medium, b = broad, w =Weak, vw = very weak, mb = medium broad and sh = shoulder

Table 3.4 Infrared spectral bands (cm-1) of EBCPH2(L

1H2) and its Mn(III) complexes

EBCPH2(L 1 H2) [Mnl1CI] [Mnl1 Br] [Mnl 1 NCS] [Mnl 1 N03] [Mnl 1Cl04] [Mnl 1CH3COO] Tentative Assignments

3300(s} 3245(s) 3240(s) 3240(s) 3245(s) 3240(s) 3235(s) VNH of sec. Amide

31 OO(w) voH of the carboxylic acid

2435(w) 2435(w) 2435(w) 2435(w) 2430(w) 2435(w) 2430(w)

2355(w) 2355(w) 2355(w) 2355(w) 2355(w) 2360(w) 2355(w)

2065(s) vc-N (Thiocyanate)

1860(w) 1860(w) 1860(w) 1860(w) 1860(w) 1855(w) 1860(w) 1785(w) v1 +v4 N03 coordinated

1775(w)

1700(s) vc=o of carboxylic acid ,-

1620(s) 1622(s) 1622(s) 1624(s) 1620(s) 1622(s) 1623(s) vc=o of amide I band

1608(s) 1605(s) 1605(s) 1585(s) 1565(s) 1590(s) vc=o asy. of coordinated

carboxylate group

1560(s) 1555(s) 1535(s) 1550(m) 1540(m) 1550(s) 1535(s) VNH inplane amide II band

1445(m) v4 N03 coordinated

1415(s) 1410(s) 1415(s) 1405(m) 1385(s) 1405(s) vco sym. of coordinated

carboxylate group

1385(vs) v1 N03 coordinated

1375(s) 131 O(m) 1335(w) 1315(s) 1345(w) 1355(m) 1335(w) VCN + NH bending

amide Ill, combination band

1220(m) 1215(w) 1220(w) 1215(w) 1220(w) 121 S(vw) 1215(w)

Table 3.4 {contd ...... } EBCPH2(L

1H2) [Mnl

1CI] [Mnl1 Br] [Mnl

1NCS] [MnL

1 NOs] [Mnl 1 CIQ4] [Mnl

1 CH3COO] Tentative Assignments

1110(s) v4 CI04 coordinated

1085(m) v1 CI04 coordinated

1060(w) 1055(w) 1075(w) 1050(m) 1060(w) 1060(w) 1060(w)

1045(m) v2 N03 coordinated

1005(m) 980(m) 985(m) 980(w) 1 OOO(m) 1000(m) 1 OOO(m)

950(w) 950(w) 950(w) 950(w) 950(w) 955(w) 950(w)

940(w) v2 C104 coordinated

860(m) 860(m) 855(m) 860(m) 860(m) 860(m) 865(w)

835(m) v6 rocking of N03 N

785(w) 785(w) 770(w) 785(w) 780(w) 780(w) 765(w)

680(vw) 680(vw) 680(vw) 670(w) 670(vw) 650(w)

640(m) v3 CI04 coordinated

630(m) vs Cl04 coordinated

585(w) 565(w) 580(w) 600(w) 580(w) 570(w) VM-N

520(w) 520(w) 525(w) 520(w) 520(w) 520(w) 520(w)

485(m) NCS deformation

465(w) 475(w) 470(w) 465(w) 460(w) 455(w) VM-0

s=strong, vs=very strong, m = medium, b = broad, w =weak, vw = very weak, mb = medium broad and sh = shoulder

Table3.5 Magnetic susceptibities and magnetic moments of Fe(III), Cr(III) and Mn(III) complexes of EBCPH2 SI. Complex XMX10 6

No. cgs.units

1 [Fe(EBCP)CI] 9000

2 [Fe(EBCP)Br] 6914

3 [Fe( EBCP)NCS] 5827

4 [Fe(EBCP)N03] 8489

5 [Fe(EBCP)CI04] 7865

6 [Cr(EBCP)CI] 6176

7 [Cr(EBCP)NCS] 5806

8 [Mn(EBCP)CI] 9525

9 [Mn(EBCP)Br] 9757

10 [Mn(EBCP)NCS] 10131

11 [Mn(EBCP)N03] 10103

12 [Mn(EBCP)Cl04] 10006

13 [Mn(EBCP)CH3COO] 9881

XoX106

c.g.s.units

142

153

150

137

150

142

150

142

153

150

137

150

152

x'MX106

c.g.s. units

9142

7067

5977

8626

8015

6218

5956

9667

9910

10281

10240

10156

10033

XM=Molar susceptibility xo=Diamagnetic correction X'M = corrected Molar susceptibility

µett· At 298K

BM

4.67

4.10

3.77

4.53

4.37

3.85

3.76

4.80

4.86

4.95

4.94

4.92

4.89

Table 3.6 Absorption bands of Fe(III) complexs of EBCPH2

SI. Complex Amax V Assignments

No. nm cm-1

1 [Fe(EBCP)CI] 380 26,315 Charge Transfer

500(vw) 20,000 6A1g74T1g

2 [Fe(EBCP)Br] 380 26,315 Charge Transfer

500(vw) 20,000 6 74 00

A1g T1g .j::,..

3 [Fe(EBCP)NCS] 380 26,300 Charge Transfer

495(vw) 20,200 6 74 A1g T1g

4 [Fe(EBCP)NOs] 380 26,300 Charge Transfer

495(vw) 20,200 6 74 A1g T1g

5 [Fe(EBCP)Cl04] 380 26,315 Charge Transfer

495(vw) 20,200 6 74 A18 T1g

vw =very weak

Table 3.7 Absorption bands of Cr(III) complexs of EBCPH 2

SI. Complex Amax No. nm

1 [Cr(EBCP)CI] 375

460(w)

645(w)

2 [Cr(EBCP)NCS] 375(w)

570(b)

b = broad, w = weak

V

cm·1

26,660

21670(w)

15500(w)

26660(w)

17575(b)

Assignments

Charge Transfer

4 74 A2g T 1g

(F)

4 74 A2g T2

g(F)

Charge Transfer

4 �4 A2g-, T 1g(F)

00

u,

Table 3.8 Absorption bands of Mn(lIl) complexs of EBCPH2

81. Complex Amax v Assignments

No. nm cm-1

1 [Mn(EBCP)CI] 363(mb) 27550(mb) Charge Transfer

504(b) 19850(b) 5 ~5Eg T2g

2 [Mn(EBCP)Br] 360(mb) 27750(mb) Charge Transfer

504(b) 19,840 5 -75Eg T2g

3 [Mn(EBCP)NCS] 360(mb) 27750(mb) Charge Transfer00

5 ~50\

504(b) 19840(b) Eg T2g

544(sh) 18,380(sh)

4 [Mn(EBCP)NOs] 363(mb) 27550(mb) Charge Transfer

504(b) 19850(b) 5 ~5Eg T2g

5 [Mn(EBCP)CI04] 363(mb) 27560(mb) Charge Transfer

503(b) 19880(b) 5 ~5Eg T2g

6 [Mn(EBCP)CH3COO] 360(mb) 27750(mb) Charge Transfer

504(b) 19840(b) 5Eg~5T2g

b =broad, mb =medium broad and sh =shoulder

87

Table 3.9 The observed and calculated sin28, (hkl) values and relativ intensities of [Fe{EBCP}CI]

Line No. [hkl] sin29 observed sin

28 calculated Relative intensity

1 (100) 0.0027 0.0026 62

2 · (010) 0.0030 0.0036 100

3 (110) 0.0066 0.0062 45

4 (200) 0.0104 0.0104 59 5 ( 111 ) 0.0117 0.0118 42

6 (210) 0.0137 0.0140 46

7 (120) 0.0176 0.0170 21

8 (300) 0.0239 0.0234 52

9 (112) 0.0283 0.0286 20

10 (221) 0.0314 0.0304 19

11 (202) 0.0334 0.0328 25

12 (150),(322) 0.0594 0.0602 54

13 (123) 0.0670 0.0674 39

14 (510) 0.0694 0.0686 62

15 (501) 0.0719 0.0706 28

16 (340) 0.0811 0.0810 40

17 (133) 0.0935 0.0932 28

18 (024) 0.1043 0.1040 37

19 (043),(620) 0.1090 0.1080 49

20 (433) 0.1243 0.1244 54

21 (362) 0.1356 0.1358 25

22 (005),(260) 0.1399 0.1400 20

23 (344) 0.1697 0.1706 44

24 (263) 0.1903 0.1904 15

25 (560) 0.1943 0.1946 54

26 (652) 0.2065 0.2060 37

27 (206) 0.2120 0.2120 23

28 (126) 0.2176 0.2186 22

29 (345) 0.2209 0.2210 20

30 (660) 0.2239 0.2232 25

31 (316) 0.2279 0.2286 19

32 (662) 0.2449 0.2456 58

33 (096) 0.2595 0.2592 25

34 (504) 0.2850 0.2842 27

35 (645) 0.2890 0.2912 25

36 (156) 0.2939 0.2942 32

37 (256) 0.3008 0.3020 26

38 (626) 0.3088 0.3096 36

39 (636) 0.3260 0.3276 30

40 (066) 0.3320 0.3312 28

41 (648) 0.3520 0.3528 31

a=17.5544A, b=14.9184A and c=11.9613A

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