c:j{5 ppe/l( -i i i - shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/99242/8/08_chapter...
TRANSCRIPT
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
i I"" ..
i:. ·t" il .. 11r��
!
I
!"
i
1· I
I
I I I
!·I I I
! i i j. I 1·
i i
1· i·'' i � : .
....
· 1}.. j.;' " ·I:... , '.
·:. j ... : ":
1· ..
I· . . . � .
I .. : .. . / ....... ,·.:: . . ..... .
! :: . .
! ! ! ...
: :
:
I
" .. "' .1 .... ,,' i ! i
88
'I
'" i• i·
., • 1:·1
'' 'I
;� . O' -a. (.) co w -Q) u. ......