Synthesis, characterization, thermal decomposition, and antimicrobial studies of copper(I) complexes of 1,3-dihydro-4,5-di(4-methoxyphenyl)imidazolin- 2-thione

Article abstract of DOI:10.1080/15533170500357855

The reaction between 1,3-dihydro-4,5-di-(4-methoxyphenyl) imidazolin-2-thione (MDPIT) with seven different copper(II) salts were carried out to synthesize and characterize the corresponding complexes. These complexes have the general formulae [CuLX(H

Full text of DOI:10.1080/15533170500357855

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Synthesis, Characterization, Thermal Decomposition,
and Antimicrobial Studies of Copper(I) Complexes of
1,3-Dihydro-4,5-Di(4-Methoxyphenyl)Imidazolin-2-
Thione
Saradamma Jayasree a & Kuttamath Kunniyur Aravindakshan a
a Department of Chemistry , University of Calicut , Kerala , India
Published online: 31 Jan 2012.
To cite this article: Saradamma Jayasree & Kuttamath Kunniyur Aravindakshan (2005) Synthesis, Characterization, Thermal
Decomposition, and Antimicrobial Studies of Copper(I) Complexes of 1,3-Dihydro-4,5-Di(4-Methoxyphenyl)Imidazolin-2-
Thione, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 35:10, 855-863, DOI:
10.1080/15533170500357855
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Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry, 35:855–863, 2005
Copyright # 2005 Taylor & Francis, Inc.
ISSN: 1553-3174 print/1532-2440 online
DOI: 10.1080/15533170500357855
Synthesis, Characterization, Thermal Decomposition,
and Antimicrobial Studies of Copper(I) Complexes of
1,3-Dihydro-4,5-Di(4-Methoxyphenyl)Imidazolin-2-Thione
Saradamma Jayasree and Kuttamath Kunniyur Aravindakshan
Department of Chemistry, University of Calicut, Kerala, India
1983). However, investigations on the omplexation behaviour
The reaction between 1,3-dihydro-4,5-di-(4-methoxyphenyl) of aryl substituted imidazolin-2-thiones are scanty (Mohanan
imidazolin-2-thione (MDPIT) with seven different copper(II)
salts were carried out to synthesize and characterize the corre-
sponding complexes. These complexes have the general formulae
[CuLX(H2O)], where X 5 OAc, Cl, Br, NO3, ClO4 or CNS, and
and Aravindakshan, 1989). We describe the synthesis, character-
ization, thermal decomposition and antimicrobial studies of 1,3-
dihydro-4,5-di(4-methoxyphenyl)imidazolin-2-thione (MDPIT)
and its copper(I) complexes, which are formed by the reaction
[Cu2L2(SO4)(H2O)]. Characterization of the complexes was done
by chemical analyses, molar conductance, magnetic susceptibility, between copper(II) salts and the ligand (Figure 1).
electronic, infrared and 1H NMR spectral studies. Thermo-
gravimetric studies of complexes were carried out and kinetic
parameters for the various decomposition stages were also
calculated. Preliminary investigations on the antifungal and anti-
EXPERIMENTAL
bacterial activities of the ligand and some of its complexes were
also made.
Synthesis of MDPIT
MDPIT was synthesized by a general method (Mohanan and
Aravindakshan, 1989), which involved two steps.
Keywords 1,3-Dihydro-4,5-di-(4-methoxyphenyl)imidazolin-2-thione,
copper(I) complexes, synthesis, characterization,
thermal decompression, antimicrobial studies
Preparation of Anisoin (4,40-dimethoxybenzoin)
Anisoin was prepared by refluxing a solution of anisalde-
hyde (100 mmol, 12 mL) in 50% ethanol (5 mL) with an
aqueous solution of sodium cyanide (100 mmol in 10 mL) for
2.5 h. On refrigeration, anisoin separated out.
INTRODUCTION
Imidazolin-2-thiones are versatile ligands due to the presence
of exocyclic sulfur and the ring nitrogen atoms. Their ability
to reduce copper(II) to copper(I) producing complexes with
unpredictable structures has created a lot of interest. Moreover,
these compounds are biologically active and have applications
in various other fields including corrosion prevention. The
coordination behaviour of unsubstituted imidazolin-2-thione,
their methyl- and ethyl derivatives and their saturated analogues
have been reported (Creighton et al., 1985; Raper and Crackett,
1981; Shanmugam and Sathyanarayana, 1983; Raper et al.,
Preparation of the Ligand (MDPIT)
Anisoin (50 mmol, 11.2 g) and ammonium thiocyanate
(120 mmol, 9.1 g) were refluxed in isoamyl alcohol (250 mL)
for about 1 h. On cooling, an ivory coloured solid compound
separated out, which was filtered and washed thoroughly
with diethylether and dried over P4O10. It was then crystallized
from ethanol.
Preparation of Copper(I) Complexes of MDPIT
A methanolic solution (20 mL) of the ligand (1 mmol,
0.313 g) was kept at refluxing temperature and to it was
added slowly a methanolic solution (20 mL) of the copper(II)
salt (1 mmol). Some complexes precipitated out instantly,
while others formed only after refluxing for 1 h. The solid com-
plexes were filtered, washed thoroughly with methanol and
dried under reduced pressure over P4O10. The thiocyanate
complex was prepared by adding a methanolic solution
(20 mL) of copper(II) acetate (1 mmol, 0.200 g) to a methanolic
Received 24 May 2004; accepted 16 August 2005.
The authors thank Dr. M. P. Kannan, Professor and former Head of
the Department of Chemistry, University of Calicut and the Regional
Sophisticated Instrumentation Centre, Central Drug Research Insti-
tute, Lucknow, and the Regional Research Laboratory, Trivandrum,
for providing laboratory facilities. Thanks are also due to the Univer-
sity Grants Commission, New Delhi for financial assistance.
Address correspondence to Kuttamath Kunniyur Aravindakshan,
Department of Chemistry, University of Calicut, Kerala 673 635,
India. E-mail: aravindkuttamath@yahoo.com
855

856
S. JAYASREE AND K. K. ARAVINDAKSHAN
FIG. 2.
Thione-thiol tautomeric forms of the ligand MDPIT.
FIG. 1.
Structure of the ligand MDPIT.
The formation of the complexes may be represented by the
following equation:
solution (20 mL) of the ligand (1 mmol, 0.313 g) containing a
stoichiometric quantity of ammonium thiocyanate (1 mmol,
0.076 g).
3½C17H16O2Sꢀ þ CuX2nH2O
! ½CuðC17H16O2SÞXH2Oꢀ þ C17H15O2ꢁS–S–O2H15C17
þ HX þ ðn ꢁ 1ÞH2O þ Hþ
ð1Þ
Analytical Methods
Metal contents were determined by standard analytical or
atomic absorption spectrophotometric methods. The anions
present in the complexes were determined by standard
methods (Vogel, 1978). Sulfate was determined gravimetri-
cally as barium sulfate. Chorine and bromine were determined
by Volhard’s method after sodium carbonate fusion and dissol-
ution in nitric acid (Vogel, 1978). Thiocyanate was determined
gravimetrically as silver thiocyanate and for perchlorate, the
Kurz method was used (Vogel, 1978). Carbon, hydrogen and
nitrogen were determined by microanalysis using a Hitachi
CHN–O rapid analyzer. Molar conductances of the complexes
were determined using 1023 M solutions in DMF on a model
305 Systronic conductivity bridge and a dip-type cell, cali-
brated with a solution of AnalaR potassium chloride.
Magnetic susceptibilities of the complexes were determined
on a Gouy balance using Hg[Co(CNS)4] as calibrant.
Formulae and General Properties of the Complexes
1
2
Reactions of CuX2, where X ¼ OAc, Cl, Br, NO3, SO4,
ClO4 or CNS, with MDPIT were carried out and in all cases
light-coloured complexes were formed. The analytical data
(Table 1) correspond to the formula [CuLX(H2O)], where
X ¼ OAc, Cl, Br, NO3, ClO4 or CNS. The sulfato complex
exists as a dimer of the formula [Cu2L2(SO4)(H2O)2].
Molar Conductance
The molar conductance values of 1023 M solutions of all
seven complexes in DMF were determined (Table 2). The
values are lower than that expected for a 1:1 electrolyte in
DMF, indicating that the complexes act as non-electrolytes,
i.e., the anions are coordinated to the metal ions (Geary, 1971).
The electronic spectra of the compounds were recorded on a
Shimadzu UV-Vis-1601 spectrophotometer using 1023 M sol-
utions in DMF. The IR spectra were recorded using KBr discs
Magnetic Behaviour
The magnetic susceptibility values of the solid complexes
were determined using a Gouy balance at room temperature
and the values indicate that the complexes are diamagnetic in
nature (Earnshaw, 1968). During complex formation, the
copper(II) salts are reduced to copper(I) by the ligand and
the excess of the ligand get oxidized to disulfide,
C17H15O2–S–S–O2H15C17 (Purushothaman, 1985) (Eq. (1)).
1
on a 8101 Shimadzu FTIR spectrophotometer. The H NMR
spectra of the ligand and its copper(I) acetate complex were
recorded in CDCl3 on a Varian 300 NMR spectrometer.
Thermal analyses were carried out on a Metler TA 4000
thermal analysis system with the following operational charac-
teristics: heating rate, 208 min21; atmosphere, static air; sample
size, 2–10 mg; crucible, platinum. Kinetic parameters for the
various stages of decomposition were calculated using differ-
ent equations. The calculations were done using a computer
programme written in Fortan 77. Antibacterial studies were
conducted using the disc-diffusion method and antifungal
studies using the cup-plate method (Murray et al., 1995).
Electronic Spectra
The electronic spectra of the complexes were recorded in
DMSO, but they do not register any bands characteristic of
Cu(II) ions in the visible region. This confirms the observation
that the complexes contain copper in the þ1 oxidation state
(Figgis, 1967). The pale colours of the complexes further
support this observation.
RESULTS AND DISCUSSION
The reaction of anisoin with ammonium thiocyanate yielded
1,3-dihydro-4,5-di(4-methoxyphenyl)imidazolin-2-thione as
ivory coloured, fine powder. There exist thione-thiol tautomer-
Infrared Spectra
The important IR spectral bands and their tentative assign-
ism of the ligand in solution, but in the solid, it exists as the ments are given in Table 3. The ligand spectrum contains a
thione (Shanmugam and Sathyanarayana, 1983) (Figure 2).
broad band of strong intensity at 3045 cm21. This may be

857

858
S. JAYASREE AND K. K. ARAVINDAKSHAN
assigned to the vibrational frequency of the NH group. The
TABLE 2
Molar conductances of copper(I) complexes of 1,3-dihydro-4,5-
di(4-methoxyphenyl)imidazolin-2-thione (MDPIT) (L)
position of this band and its broad nature indicate the
presence of NH. . . . S hydrogen bonding. The absence of n
(SH) near 2500 cm21 in the ligand spectrum indicates the dom-
inance of the thione form of the ligand in the solid state
(Bellamy, 1978).
Molar conductance in
DMF (ohm21 cm2 mol21
)
Sl. no.
Complex
Four characteristic thioamide bands I, II, III, and IV (Rao,
1963) are seen in the spectrum of MDPIT. The thioamide I
bands are at 1570 and 1458 cm21, with shoulders at 1514
and 1373 cm21. These are the coupled bands arising from
n(CN) and d(NH). A medium-intensity band at 1249 cm21 is
assigned to the thioamide band II, which has major contri-
butions from n(C55S), n(CN) and d(NH). The thioamide
(1)
(2)
(3)
(4)
(5)
(6)
(7)
[CuL(OAc)(H2O)]
[CuLCl(H2O)]
[CuLBr(H2O)]
6.3
12.27
15.43
15.72
9.5
[CuL(NO3)(H2O)]
[Cu2L2(SO4) (H2O) ]
2
[CuL(ClO4) (H2O)]
[CuL(CNS)(H2O)]
9.7
12.5
TABLE 3
Significant infrared spectral bands (cm21) of MDPIT, its copper(I) complexes, and their assignments
n(OH) of
coord. water
Compound
MDPIT (L)
n(N–H)
TA I
TA II
TA III
1090 s
TA IV
792 m
n(C55S)
Anion
—
—
3045 b
1570 s
1514 sh
1458 s
1249 s
1211 m
536 s
1373 sh
1528 s
1506 sh
1458 s
[CuL(OAc)(H2O)]
[CuLCl(H2O)]
3242 b
3136 b
3251 b
3420 b
3327 b
3060 b
3053 b
3143 b
3109 b
3049 b
1247 s
1253 s
1253 s
1251 s
1251 s
1029 s
1028 s
1026 s
1076 s
1070 s
773 m
780 m
773 m
770 m
770 m
532 s
532 s
522 s
534 s
536 s
1640 s
1400 s
1373 sh
1550 s
1514 sh
1458 s
—
—
1370 sh
1558 s
1508 sh
1458 s
[CuLBr(H2O)]
1378 sh
1571 s
1515 sh
1458 s
[CuL(NO3)(H2O)]
[Cu2L2(SO4)(H2O)2]
1408 s
1299 m
1000 s
1384 sh
1571 s
1519 sh
1460 s
1140 s
1030 m
990 s
577 m
680 m
461 m
1130 s
1081 s
921 m
623 m
2123 m
727 s
[CuL(ClO4)(H2O)]
CuL(CNS)(H2O)]
3421 b
3246 b
3145 b
3060 b
1575 s
1512 sh
1460 s
1253 s
1247 s
1063 s
1028 s
770 m
771 m
530 s
536 s
1388 sh
1570 s
1506 sh
1458 s
1373 sh
b ¼ broad; sh ¼ shoulder; TA ¼ thioamide band.

MDPIT REACTIONS WITH SEVEN COPPER SALTS
859
TABLE 4
Significant H NMR spectral assignment of MDPIT and its copper(I) nitrate complex
1
Compound
L
d (ppm)
Proton
2.50 (s, 1H)
3.55 (s, 3H)
3.35 (s, 3H)
–SH
OCH3
7.27–7.24 (m, 10H)
6.92–6.88 (m)
3.50 (m, 6H)
Aromatic protons
and imidazole NH
OCH3
[CuL(NO3)(H2O)]
3.76 (s, 2H)
7.41–6.85 (m, 10H)
Coord. water
Aromatic protons
and imidazole NH
s ¼ singlet, m ¼ multiplet.
band III at 1090 cm21 has contributions from n(CN) and 3200 cm21 in the spectra of all complexes may be assigned
n(C55S). The thioamide band IV is present at 792 cm21. The to n(OH) of coordinated water. The thioamide bands I and II
n(C55S) is assigned at 536 cm21. Thus the presence of four do not show much change upon coordination. In the spectra
characteristic thioamide bands and the absence of n(SH), of the complexes, the thioamide band III shows a shift to
confirm the ligand to be in the thione form in the solid state.
lower frequency of 60–70 cm21. Similarly, the thioamide
In the spectra of all complexes of MDPIT, n(NH) is shifted band IV shows a shift to lower frequency of 20 cm21 in the
to higher frequency indicating the non-participation of cyclic spectra of the complexes. These changes indicate the coordi-
nitrogen atoms in coordination. Broad bands observed near nation of the ligand through the thione sulfur atom.
TABLE 5
Thermal decomposition data of copper(I) complexes of MDPIT
Mass-loss from
Decomp.
Decomp.
stage
temp.
range (8C) TG
Independent
pyrolysis
Complex
Calculated
Stages of decomposition
[CuL(OAc)(H2O)]
1
2
3
100–150
4.00
—
—
3.97
16.97
82.44
[CuL(OAc)H2O] ! CuL(OAc)
[CuL(OAc)H2O] ! CuL
[CuL(OAc)H2O] ! CuO
250–400 17.56
450–600 83.00
83.20
[CuLCl(H2O)]
1
2
3
4
100–180
3.00
—
—
4.10
12.45
26.84
81.46
[CuLCl(H2O)] ! CuLCl
250–300 12.00
300–400 25.50
500–700 84.00
[CuLCl(H2O)] ! CuL
—
81.76
[CuLCl(H2O)] ! CuL-2 OCH3
[CuLCl(H2O)] ! CuO
[CuLBr(H2O)]
1
2
3
4
100–150
4.30
—
—
3.74
16.85
33.72
83.24
[CuLBr(H2O)] ! CuLBr
220–300 16.50
300–450 35.00
500–700 85.00
[CuLBr(H2O)] ! Cu(L-2 OCH3)Br]
[CuLBr(H2O)] ! Cu(L-2 OCH3)
[CuLBr(H2O)] ! CuO
—
84.81
[CuL(NO3)(H2O)]
[Cu2L2(SO4)(H2O)2]
1
2
3
4
100–150
4.00
—
—
3.97
10.73
31.10
82.60
[CuL(NO3)H2O] ! CuL(NO3)
[CuL(NO3)H2O] ! Cu(L-2 OCH3)NO3
[CuL(NO3)H2O] ! Cu(L-2 OCH3)
[CuL(NO3)H2O] ! CuO
150–300 10.50
200–450 30.50
450–600 84.00
—
83.46
1
2
3
4
5
100–150
4.40
—
—
4.05
11.11
46.33
74.63
82.07
[Cu2L2(SO4)(H2O)2] ! Cu2L2SO4
! Cu2(L, L-2 OCH3)SO4
! Cu2(L-2 OCH3)SO4
! Cu2SO4
150–200 11.04
200–400 46.16
400–500 76.60
650–750 81.11
—
—
82.00
! 2CuO

860
S. JAYASREE AND K. K. ARAVINDAKSHAN
IR Features of Coordinated Anions in the Complexes
In all the complexes, the anions except sulfate act as mon-
adentate ligands. The wide separation between two n(C55O)
bands of acetate ion shows its monodentate nature. The denti-
city of nitrate ion is clear from the separation between n1 and
n4, which is of the order of 100 cm21 in the present case. There-
fore, the nitrate ion is acting as a monodentate one (Babu and
Indrasenan, 1988). The sulfate ion in [Cu2L2(SO4)(H2O)] is
acting as a bidentate-bridging ligand, which is evident from
the positions and the natures of n1, n2, n3 and n4 bands. The
split nature of the n3 band of the perchlorate ion indicates its
monodentate nature (Nakamoto, 1986). In the thiocyanate
complex, n1 is present near 2100 cm21 indicating that the thio-
cyanate ligand is S-bonded to the metal ion (Rao, 1963).
may be assigned to the aromatic protons and the imidazole
NH (Purushothaman, 1985). The singlet at 2.50 ppm in the
ligand spectrum is due to –SH, which is absent in the
spectrum of the complex. This shows that the ligand exists in
the thiol form in solution (Shanmugam and Sathyanarayana,
1983). Hence, the peaks of protons of two OCH3 groups are
slightly different in the ligand spectrum while they form a set
of multiplets in the spectrum of the complex. This confirms
the fact that the ligand coordinates to the metal ion in the
thione form. A singlet at 3.76 ppm in the spectrum of the
complex may be assigned to the protons of the coordinated
water.
THERMAL DECOMPOSITION STUDIES
The thermal analyses data of the complexes are summarized
1H NMR SPECTRA
The spectra of the ligand and its copper(I) nitrate complex, in Table 5 and the thermograms are shown in Figure 3.
recorded in CDCl3 (Table 4) show multiplets near 7 ppm. They The kinetic parameters, such as energy of activation (E),
FIG. 3.
TG and DTG curves of metal complexes.

MDPIT REACTIONS WITH SEVEN COPPER SALTS
861
pre-exponential factor (A) and change in entropy (Ds) were kinetic parameters for the 2nd and 3rd stages were calculated.
calculated for the important stages of decomposition using The values of energy of activation for the two stages are com-
three different equations, the Coats and Redfern (1963), parable as they involve rupture of metal-ligand bonds.
Horowitz and Metzger (1963) and MacCallum and Tanner
(Ninan et al., 1986) equations and the results are summarized decomposition, in which the coordinated water, chloride ion,
in Table 6. methoxy groups and the rest of the ligand decomposed
The copper(I) chloride complex followed a four-staged
The copper(I) acetate complex decomposed in three stages. successively giving CuO as the final product. The kinetic
In the first stage, loss of coordinated water and in the second parameters for the 2nd, 3rd and 4th stages were calculated.
stage, loss of coordinated acetate ion resulted. In the third Comparatively high values of activation energies for the 2nd
stage, the complex completely decomposed to CuO. The and 4th steps may be due to the rupture of metal-ligand
TABLE 6
Kinetic parameters for thermal decomposition of copper(I) complexes of MDPIT
Complex
Decomp. stage
2nd
Eqn. used
E, kcals mol21
A, s21
DS, kcals deg21 mol21
[CuL(OAc)(H2O)]
Coats–Redfern (CR)
Horowitz–Metzger (HM)
17.01
15.29
17.54
16.79
20.75
18.07
2.01 ꢂ 103
2.98 ꢂ 103
2.89 ꢂ 103
68.38
244.96
248.76
239.67
252.16
241.40
237.80
MacCallum–Tanner (MT)
CR
3rd
HM
MT
92.95
93.91
[CuLCl(H2O)]
2nd
3rd
4th
CR
11.89
11.93
13.46
9.16
5.9 ꢂ 105
9.5 ꢂ 105
3.6 ꢂ 105
2.5 ꢂ 102
2.3 ꢂ 102
3.0 ꢂ 102
1.4
249.80
250.70
241.14
258.19
253.77
251.91
260.02
254.92
258.32
HM
MT
CR
HM
MT
CR
11.72
9.75
12.48
14.13
11.67
HM
MT
1.6
1.2
[CuLBr(H2O)]
2nd
4th
CR
6.75
6.50
0.75
0.38
0.76
9.66
12.09
18.60
260.31
261.66
246.54
256.33
251.31
241.30
HM
MT
CR
6.87
15.67
19.98
17.45
HM
MT
[CuL(NO3)(H2O)]
2nd
3rd
4th
CR
7.60
9.85
7.62
11.9
15.81
2.80
5.08
4.08
4.28
5.42
6.72
255.31
249.83
242.58
257.96
261.35
260.49
257.66
252.62
251.66
HM
MT
CR
7.31
9.01
HM
MT
CR
7.69
8.39
12.53
16.27
13.80
HM
MT
[Cu2L2(SO4)(H2O)2]
3rd
4th
CR
14.84
16.38
13.76
11.08
14.51
12.03
3.89 ꢂ 103
4.95 ꢂ 103
2.5 ꢂ 103
5.4 ꢂ 103
7.1 ꢂ 103
7.4 ꢂ 103
240.01
243.01
235.18
256.99
251.89
253.95
HM
MT
CR
HM
MT

862
S. JAYASREE AND K. K. ARAVINDAKSHAN
TABLE 7
Antimicrobial activities of copper(I) complexes of MDPIT
Diameter of inhibition zone (mm)
Fungal strains
Bacterial strains
Aspergillus
niger
Aspergillus
parasiticus
Rhizopus
oryzae
Candida
albicans
Staphylococcus
aureus
Escherichia
coli
Pseudomonas
aeruginosa
Compound
DMSO
Nystatin
8
10
—
10
10
10
8
12
—
10
10
10
8
10
—
—
—
—
8
0
Ampicillin
L
—
10
10
10
15
—
—
11
10
—
—
—
10
—
—
10
[CuL(OAc)H2O]
[CuLClH2O]
bonds. The copper(I) bromide complex also decomposed in
four stages. Here the OCH3 groups decomposed before the
elimination of bromide ion. This may be due to the low
energy of activation for the decomposition of OCH3 groups.
The thermal decomposition of the copper(I) nitrate complex
took place in four stages. The coordinated water, two OCH3
groups, nitrate ion and the rest of the ligand decomposed suc-
cessively. The values of kinetic parameters are also compar-
able. The copper(I) sulfate complex decomposed in five
stages. Coordinated water molecules, two OCH3 of one of
the ligand, one of the ligand and rest of the ligand decomposed
successively giving Cu2SO4, which finally decomposed to
CuO. The activation energies of the steps involving M-L
bond breaking are found to be appreciably higher than those
of the other stages.
FIG. 4.
Suggested structure of the complexes.
Nystatin as standard (Murray et al., 1995). The disk-diffusion
(Murray et al., 1995) method was used for testing antibacterial
activity using Ampicillin as standard (Table 7).
The above investigations revealed that these compounds
have higher fungicidal activity than bactericidal activity.
None of these compounds were found to be active against
Rhizopus oryzae and Escherichia coli. Of the compounds
tested, none other than [CuLCl(H2O)] showed activity
against bacterial strains. The lower activities of some of the
complexes may be due to their inert nature, which prevent
their substitution reaction with metal ion centres (Murray
et al., 1995).
ANTIMICROBIAL STUDIES
Preliminary screening for antifungal and antibacterial
activities of the ligand and some of its complexes (2000 ppm
solutions in DMSO) were performed against four different
fungal and three different bacterial strains. The cup-plate
method was used for testing antifungal activity using
FIG. 5.
Suggested structure of the sulfato complex.

MDPIT REACTIONS WITH SEVEN COPPER SALTS
863
Figgis, B. N. Introduction to Ligand Fields; Wiley Interscience:
New York, 1967.
CONCLUSIONS
From the magnetic susceptibility and electronic spectral
data it was confirmed that copper is in the þ1 oxidation
state in the complexes. The pale colours of the complexes
support this observation. Analytical data indicated that the
complexes are of the type [CuLX(H2O)], where X ¼ OAc,
Cl, Br, NO3, ClO4 or CNS and [Cu2L2(SO4)(H2O)2]. The IR
Geary, W. J. The use of conductivity measurements in organic
solvents for the characterization of coordination compounds.
Coord. Chem. Rev. 1971, 7, 81–122.
Horowitz, H. H.; Metzger, G. A new analysis of thermogravimetric
traces. Anal. Chem. 1963, 35, 1464–1468.
Mohanan, A.; Aravindakshan, K. K. Synthesis and characterisation
of Cu(I) and Ag(I) complexes of 4,5-diphenylimidazole-2-thione.
Proc. Indian Acad. of Sci. (Chem. Sci.) 1989, 101 (1), 13–17.
Murray, P. R.; Baron, E. J.; Pfaller, M. A.; Tenover, F. C.;
Yolken, R. H. Manuel of Clinical Microbiology, 4th ed.;
American Society for Microbiology Press: Washington, DC,
1995; pp. 1407.
1
and H NMR spectral studies showed that in the complexes,
MDPIT acts as a neutral monodentate ligand coordinating
through the thione sulfur atom. As copper is in the þ1
oxidation state, magnetic and electronic spectral data are of
little use in assigning the geometries of the complexes. In
comparison with similar complexes (Creighton et al., 1985;
Raper and Crackett, 1981; Shanmugam and Sathyanarayana, Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordi-
nation Compounds; John Wiley and Sons: New York, 1986.
Ninan, K. N.; Krishnan, K.; Mathew, J. Addition polyimides, kinetics
of cure reaction and thermal decomposition of bismaleimides.
J. Appl. Poly. Sci. 1986, 32, 6033–6042.
1983; Raper et al., 1983), the following geometries may
be proposed for the Cu(I) complexes of MDPIT (Figures 4
and 5).
Purushothaman, E. Ph.D. Studies in the photochemistry of Imidazole-
Derivatives; Calicut University, 1985.
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