Synthesis, spectroscopic characterization and preliminary antimicrobial studies of Mn(II) and Cu(II) complexes of two thiolates; S,S'-(2,6- diaminopyridine-3,5-diyl) dibenzenecarbothioate (DBCT) and S-benzyl benzenecarbothioate (BBCT)

Article abstract of DOI:10.1155/2011/214870

S,S'-(2,6-Diaminopyridine-3,5-diyl)dibenzenecarbothioate was formed by condensing 2,6-diamino-3,5-dithiopyridine and benzoyl chloride in the presence of pyridine. Also S-benzyl benzenecarbothioate was prepared by the condensation of benzoyl chloride and p

Full text of DOI:10.1155/2011/214870

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2011, 8(1), 231-239
http://www.e-journals.net
Synthesis, Spectroscopic Characterization and
Preliminary Antimicrobial Studies of Mn(II) and
Cu(II) Complexes of two Thiolates; S,S’-(2,6-
Diaminopyridine-3,5-diyl) Dibenzenecarbothioate
(DBCT) and S-Benzyl Benzenecarbothioate (BBCT)
P. O. UKOHA§*, C.U. ALIOKE§, N. L. OBASI§ and K. F. CHAH
§Department of Pure and Industrial Chemistry
University of Nigeria, Nsukka Enugu State, Nigeria
Department of Veterinary Physiology and Parasitology
University of Nigeria, Nsukka, Enugu State, Nigeria
pius_ukoha@yahoo.com
Received 9 December 2009; Revised 11 March 2010; Accepted 19 March 2010
Abstract: S,S’-(2,6-Diaminopyridine-3,5-diyl)dibenzenecarbothioate was
formed by condensing 2,6-diamino-3,5-dithiopyridine and benzoyl chloride in
the presence of pyridine. Also S-benzyl benzenecarbothioate was prepared by
the condensation of benzoyl chloride and phenylmethanethiol in the presence
of pyridine.The complexes of these compounds were prepared using copper(II)
and manganese(II) chloride salts. The thiolates were characterized on the basis
of their electronic, infrared and NMR spectra whereas the complexes were
characterized via electronic and infrared studies. The IR spectral studies
indicate that the ligands coordinated through the carbonyl oxygen, the sulphur
atom and also with the amino group in DBCT. Antimicrobial studies on the
ligands and their complexes showed varying degrees of inhibition on the
growth of the following microorganisms; Staphylococcus aureus (ATCC
25923), Pseudomonas aeruginosa (ATCC 27853), Bacillus subtilis (ATCC
6633) and Candida albicans (ATCC 2091). The compounds showed no
activity against Escherichia coli (ATCC 25922)
Keywords: Complexes, IR, NMR Spectra, Synthesis.
Introduction
Ligands containing and coordinating through sulphur atoms have attracted much attention.
This is due to their efficacy in metal chelation therapy1, in anti-influenza, antiprotozoan,

232
P. O. UKOHA et al.
antibacterial and antiviral treatment2. Some of them have also been indicated to have high
potency as fungicides3 and pesticides4. Recently 4-aminoantipyrine thiosemicarbozones2,5
and their Co(II), Ni(II) and Cu(II) complexes were synthesized, characterized and found to
have strong antifungal activity and comparative antibacterial activity with ampicillin and
tetracycline. The recent discovery of acireductone dioxygenase (ARD), a metalloenzyme
with Ni(II) centre having the capacity to catalyse the oxidative breakdown of acireductone to
2-methylthiopropionate in Kiebsiella penumoniae6, has fuelled interest in compounds having
sulphur donor atoms.
Research into inorganic pharmaceuticals is gaining currency due to the drive for new
chemotherapeutic agents that can combat bacterial infections. At present infections caused
by bacteria constitute a serious burden to healthcare systems world wide. Antibiotic resistant
strains of bacteria are an increasing threat to animal and human health, with resistance
mechanisms having been described for virtually all known antimicrobials currently available
for clinical use. A way of overcoming antibiotic resistance of pathogenic microorganisms is
by using new compounds that are not based on existing synthetic antimicrobial agents7.
In this work we have synthesized two new ligands: S,S’-(2,6-diaminopyridine-3,5-diyl)
dibenzenecarbothioate (DBCT) and S-benzyl benzenecarbothioate (BBCT) having C-S
bonds. We have also prepared their Mn(II) and Cu(II) complexes and characterized
them via UV, IR and Conductance measurements. In addition, the ligands were
characterized by NMR spectral studies as well as elemental analysis. The ligands and
complexes were further investigated for their antimicrobial activities against some
bacteria and fungus. The results suggest great potential for these ligands and complexes
as antibacterial and antifungal agents.
Experimental
Manganese(II) chloride and copper(II) chloride were products of Fluka, Switzerland,
Benzoyl chloride, Phenylmethanethiol and 2,6-diaminopyridine-3,5-dithiol were obtained
from BDH, England and were used as supplied unless otherwise stated. UV Visible spectra
of the ligands and complexes were obtained on CECIL CE 9050 Spectrophotometer. FTIR
spectra of the compounds were run as Nujol mulls on Buck scientific model 500 FTIR
1
Spectrometer. 13C and H NMR spectra were recorded on YH 200 MHz Varian Mercury
1
NMR Spectrometer using DMSO and CDCl3 as solvents respectively. The H NMR Peaks
were observed at about 200 MHz and 13C NMR spectra were observed at about 50 MHz
.Elemental analysis was done using LECO-CHNS 932 Microanalysis apparatus at
Department of Pharmaceutical Sciences, University of Strathchlylde, Glasgow. Conductance
measurements for the compounds were made at 28 oC using CD 600 Milwaukee
Conductivity meter with a cell constant 1.0 cm-1. Standard solutions were prepared in
nitrobenzene. Molecular weights of the ligands and complexes were determined
cryoscopically based on the depression of melting point of camphor as reported elsewhere8.
All other reagents were of analytical grade and were used as supplied.
Synthesis of S,S’-(2,6-diaminopyridine-3,5-diyl)dibenzenecarbothioate (DBCT)
5.8 mL (0.05 mole) of benzoyl chloride, 2.925 g (0.025 mole) 2,6-diaminopyridine-3,5-
dithiol and about 5 mL of pyridine were stirred in a round-bottomed flask until evolution of
HCl ceased. Then 2 mL of distilled water and about 2 mL of pyridine were added to
eliminate any excess of the reagents. Pale green solid separated and was recrystallized with
dilute ethanol. The yield was 66%.

Synthesis, Spectroscopic Characterization
233
Synthesis of S-benzyl benzenecarbothioate (BBCT)
2.9 mL (0.025 mole) benzoyl chloride, 2.33 mL (0.025 mole) Phenylmethanethiol and about
5 mL of pyridine were mixed in a 500 mL round-bottomed flask. The mixture was heated
with stirring over a water bath until HCl fume ceased. Then about 2 mL of distilled water
and about 2 mL of pyridine were added to eliminate excess reagent. The mixture was
allowed to cool and white needle like crystals separated. The product was recrystallized with
absolute ethanol. The yield was 87.9%.
Synthesis of Mn(II) complex of DBCT and BBCT
1.98 g (0.01 mole) MnCl2.4H2O and 7.62 g (0.02 mole) DBCT were dissolved separately in
about 10 mL of absolute ethanol. The two solutions were mixed in a 500 mL round-
o
bottomed flask and refluxed for 1 h under constant stirring at 50 C. The resulting greenish
solution was allowed to cool after which a pale green crystals separated. They were filtered,
washed with ethanol and dried in vacuo in a desicator over CaCl2.
Also BBCT was reacted with MnCl2.4H2O in the ratio of 2:1 following the method adopted
for DBCT. The green solution formed was allowed to cool. Need-like white crystals separated
after 120 hours. The crystals were washed with ethanol and dried in vacuo over CaCl2.
Synthesis of Cu(II) complexes of DBCT and BBCT
7.62 g (0.02 mole) DBCT and 1.705 g (0.01 mole) CuCl2 .2H2O were dissolved separately in
about 10 mL of absolute ethanol. The two solutions were mixed in a 500 mL round-bottomed
o
flask and refluxed under constant stirring for 1 h at 50 C. After cooling a pale green solid
separated. It was filtered, washed with ethanol and dried in vacuo over CaCl2.
Following above procedure, 4.56 g (0.02 mole) BBCT was reacted with 1.705 g (0.01 mole)
CuCl2.2H2O. The solution was allowed to cool and shiny white crystals separated after 72
h. The crystals were filtered, washed with ethanol and in vacuo over CaCl2.
Antimicrobial properties
The antimicrobial properties of DBCT, BBCT and their Mn(II) and Cu(II) complexes
were determined against Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC
6633), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922) and
Candida albicans (ATCC 2091) using the agar-well diffusion method9. Each Mueller-
Hinto agar (and sabouraud dextrose agar for Candida albicans) plate was inoculated with
0.1 mL of three hours broth culture of each test organism. Wells (7 mm in diameter and
2.5 mm deep) were cut into the inoculated agar and labeled from one to seven. 50 µL of
20 mg/ mL dimethylsulfoxide solution (DMSO) of DBCT, BBCT, [Mn(DBCT)Cl2],
[Mn(BBCT)2 (H2O)2]2+, [Cu(BBCT)2Cl2] and [Cu(DBCT)Cl2] respectively were placed in
wells labeled 1 to 6 and 20% v/v DMSO was delivered into the 7th well. The set up was
left on the lab bench for one hour for the solutions and DMSO to diffuse into the media.
The plates were then incubated at 37 oC for 24 h. Assessment of antimicrobial activity was
based on the measurement of the diameter of inhibition zone (1ZD) around the wells. The
experiment was replicated three times and the mean IZD was recorded to the nearest
whole millimeter.
Results and Discussion
The reaction of benzoyl chloride with 2,6-diaminopyridine-3,5-dithiol afforded S,S’-(2,6-
diaminopyridine-3,5-diyl)dibenzenecarbothioate according to Scheme 1. Also the reaction of

234
P. O. UKOHA et al.
phenylmethanethiol with benzoyl chloride yielded S-benzyl benzenecarbothioate as seen in
Scheme 2. Reactions of MnCl2.4H2O and CuCl2. 2H2O separately with the ligands afforded
the complexes.
O
O
SH
HS
S
S
O
Pyridine
+
2
Cl
NH2
H2N
NH2
H2N
N
benzoyl chloride
2,6-diaminopyridine-3,5-dithiol
S,S- (2,6-diaminopyridine-3,5-diyl) dibenzene carbothioate
Scheme 1. Synthesis of DBCT
O
O
Cl
Pyridine
SH
S
+
HCl
+
S-benyl benzenecarbothioete
phenylmethanethiol
benzoyl chloride
Scheme 2. Synthesis of DBCT
Some physical data of the ligands and complexes are presented in Table 1 while Table 2
gives the elemental data of the ligands. There is close agreement between what is expected
and what was determined. The crystalline solids were found to be stable and on storage for
about 12 months their nature did not changed. The molar conductance values suggest the
complexes to be most probably non-electrolytes as there is no appreciable dissociation
except [Mn(BBCT)2(H2O)2]2+ which is most likely a 2:2 electrolyte2.
Table 1. Some physical data of the ligands and complexes
%
Yield
66
Ωm,
Compound
DBCT
BBCT
[Cu(DBCT)Cl2]
[Cu(BBCT)2Cl2]
[Mn(DBCT)Cl2]
Colour
Melting point, oC
ohm-1.cm2 mole-1
Pale green
White
Green
178-180
115-117
287-290
133-135
291-292
108-110
-
-
88
75
8.52
8.72
62
68
White
Dirty green
Shiny white
12.01
57.60
[Mn(BBCT)2(H2O)2]2+ 79
Table 2. Analytical data of the ligands
%C %H
Molecular mass
Compd
%N
%S
Calcd. Found Calcd. Found Calcd. Found Calcd. Found Calcd. Found
381.48 379.98 59.82 62.46 3.96 4.38 11.02 10.89 16.81 18.12
DBCT
BBCT
228.31 230.01 73.65 71.80 5.30 6.10
-
-
14.04 13.81
Job’s continuous variation method and slope ratio method respectively were employed
in the determination of the composition of the complexes. [Cu(BBCT)2Cl2] was analyzed at
337 nm, [Mn(DBCT)Cl2] at 247 nm, [Cu(DBCT)Cl2] at 343 nm and [Mn(BBCT)2(H2O)2]2+
at 247 nm. The results indicate 1:1 metal to ligand ratio for the complexes of DBCT and 1:2
metal to ligand ratio for the BBCT complexes. The results could be interpreted to mean a
generalized MLX2 octahedral complexes of DBCT with Mn(II) and Cu(II) where DBCT is
tetradentate and ML2X2 octahedral complexes of BBCT where BBCT is bidentate. DBCT could
ligate to the metal through S, O or N atoms. BBCT is limited to the O and S atoms for ligation.

Synthesis, Spectroscopic Characterization
235
Electronic spectra
DBCT shows a strong absorption at 247 nm and BBCT absorption was observed at 258 nm
in the UV. These results as seen in Table 3 are likely due to π →π* and n →π* transitions in
the ligand molecules. The spectrum of [Cu(DBCT)Cl2] and [Cu(BBCT)2Cl2] are similar
showing new peaks at 337 nm (29656 cm-1) and at 343 nm (29172 cm-1) respectively. These
bands are likely due to metal to ligand charge transfer. The same deduction was made for
Cu(II) complexes5,10. The bands at 883 nm for [Cu(BBCT)2Cl2] and 886 nm for
[Cu(DBCT)Cl2] are attributed to a distorted octahedral geometry in the copper complexes. It
has been reported that d→d transitions in copper complexes around 600 nm and 900 nm are
indicative of a square pyramidal arrangement or a pseudo-octahedral environment with weak
axial interaction for the Cu(II) complex11. The spectrum of the Mn(II) complexes shows a
shift to lower energies all centered between 224 nm to 247 nm. The shift to low wavelengths
is probably the result of weak interaction between the ligands and Mn(II) or due to weak
interaction between solvent molecules and the metal ions.
Table 3. Electronic spectral data (nm) of compounds
Compound
1, λmax
247
258
2, λmax
-
3, λmax
DBCT
BBCT
[Cu(DBCT)Cl2]
[Cu(BBCT)2Cl2]
[Mn(DBCT)Cl2]
[Mn(BBCT)2(H2O)2]2+
-
-
-
247
248
337
343
247
235,224
886
883
894
-
247
247,242
Infrared spectral data
The infrared absorption frequencies of the ligands and their complexes are displayed in
Tables 4 and 5. In Table 4, the broad absorption peaks between 3457 cm-1 and 3416.22 cm-1
indicates N-H vibration. The peaks at about 2900 cm-1- 2300 cm-1 have been assigned to C-H
stretching vibration. There are no bands between 2700 cm-1-2500 cm-1. This is indicative of
absence of thiol (SH) bands12,13, this shows that the ligands were formed as proposed by the
clipping of the S-H bonds of the thiols to give –S-C=O. A comparison of the IR data of
DBCT with that of the complexes as regards the N-H band shows that for [Cu(DBCT)Cl2]
there was little or no shift in its band but that of [Mn(DBCT)Cl2] shifted to lower frequency
of 3416.22 cm-1 indicating ligation to Mn through H2N- but no coordination to Cu through
the amino group. Another significant absorption is that of C=O which is centered at 1690.97 cm-1
in the ligand but shifted to 1630.08 cm-1 in the copper complex indicating possible
coordination to the metal through the carbonyl group. However in the manganese complex,
the strong peak at about 1695 cm-1 remained but with emergence of a new weak band at
1621.47 cm-1 indicating a remote possibility of ligation through the carbonyl group to
manganese. The C-S bands showed up between 760 cm-1 and 690 cm-1. The bands remain
virtually unchanged in the manganese complex but shows some degree of shift in the copper
complex suggesting coordination to the copper centre through the sulfur and non-ligation to
the manganese ion through sulfur11.
In Table 5, the IR spectra of the BBCT ligand is comparable to those of the complexes.
One significant feature is the appearance of broad band at 3441.40 cm-1 in the Mn(II)
complex. This has been ascribed to the presence of coordinated water in the complex. The
carbonyl bands in the ligand are centered between 1700 cm-1 to 1669.26 cm-1.

236
P. O. UKOHA et al.
Table 4. IR spectral data (cm-1) of DBCT and its Cu(II) and Mn(II) complexes
DBCT
3455(br)
[Cu(DBCT)Cl2] [Mn(DBCT)Cl2] Assignment
3457.86(br)
3156.46(sh)
2900(s)
3416.22(br)
ν (N-H)
ν (C-H)
2853.19(s)
2800 (s)
1694.97 (s)
2850(s)
2900 (s)
2853.35(s)
1630.08(w)
1695.04(s)
1621.47(w)
1495(s)
ν (C=O)
1461.62(s)
1377.30(s)
1289.10 (w)
1255 (w)
1462.24(s)
1378.03(s)
1262.38(w)
1036.40(w)
ν (C-C) ring
ν (C-N)
1320(s)
1287.52(s)
1027.40(w)
1125.80(w)
760(w)
755(w)
718.36(m)
760(w)
710.95 (s)
710.40(s)
690.09(w)
547.05(w)
ν (C-S)
527(w)
450.80(w)
410.20(w)
560.80(w)
458.50(w)
414.26(w)
ring breathing
ν (M-O)
ν (M-N)
s= strong, m= medium, sh= shoulder, w= weak.
Table 5. IR spectral data (cm-1) of BBCT and its Cu(II) and Mn(II) complexes
BBCT
[Cu(BBCT)2Cl2] [Mn(BBCT)2(H2O)2]2+
3441.40(br)
Assignment
ν ( H2O)
ν (C-H)
2918.84(s)
2858.64(s)
1700 (w)
2918.92(s)
2669.11(w)
1788.80(w)
1696.21(s)
1582.07 (s)
1498.32 (s)
1377.32(s)
1287.90 (m)
1102.01(m)
1018.21(m)
2917(s)
2671(w)
1787.12(w)
1695.75(w)
1602 (w)
ν (C = O)
ν (C= C)
1669.26(w)
1650(w)
1453.03 (s)
1400 (m)
1325(m)
1450.88(s)
1377.18(s)
1287.23(s)
1177.01(m)
1071.42 (m)
δ (ring)
ω (CH2)
δ (CH2) ring vibration
1215 (w)
1127.08(m)
1069.69(m)
999.89(m)
914.09(s)
804.45(s)
706.83(s)
537.50 (s)
999.39(m)
915.73 (s)
805.49(m)
710.42(s)
549.31(s)
918.34 (m)
ω (C-H) and
ω (H2O)
ν (C-S)
807.9(m)
710.89(s)
546.76(m)
γ (C-C)
Ring vibration
476.10(m)
320 (m)
457(w)
325 (w)
ν (M-O)
ν (M-S)
These bands appear at about 1696 cm-1 in the complex as only one peak. The other
medium peak at 1669.26 cm-1 in the ligand is completely missing in the complexes. This is
indicative that the ligand coordinate to the metal ions through the carbonyl groups. Shifts,

Synthesis, Spectroscopic Characterization
237
weakening or absence of peaks of ligands on coordination to metal had been interpreted in
terms of coordination through such functional group15,16. The C-S band appeared at about
710 cm-1-807 cm-1 in the ligand and complexes. The peak at 706.83 cm-1 in the ligand
shifted to 710.89 cm-1 in the Cu(II) and Mn(II) complexes respectively indicating possible
ligation to the metal centres through the sulfur atom.
In the IR spectra of the complexes of both ligands, new bands having weak to medium
intensities at 476 cm-1 to 320 cm-1 abound. These peaks are most probably metal to ligand bands
(M-O, M-Cl, M-S and M-N).the same assertions had been adopted for some metal(II) complexes
of 4-formylazohydrazoaniline antipyrine14 and aminoantipyrine thiosemicarbazone2, 5
.
The IR data of the ligands and complexes generally imply that the DBCT is tetradentate
coordinated from S, N-H2 or C=O while BBCT is bidentate coordinating through S and
C=O. The complexes of DBCT are likely octahedral complexes of the form MLX2
(M=Mn(II) or Cu(II), L= DBCT and X=Cl). BBCT complexes are presented as
[MnL2(H2O)2]X2 and [CuL2X2 ] (L= BBCT, X=Cl).
NMR data of ligands
A close look on the spectrum of this ligand, DBCT shows absence of peak around
3.5-3.8 ppm indicating non-existence of the -SH group in the ligand and confirming the
condensation reaction forming the thiocarbonyl group to have taken place. The peak at
7.95 ppm is due to ten aromatic protons on the two side rings. The singlet at 7.52 ppm is due
to the pyridine ring while the four –NH2 protons on the pyridine have their bands at 7.6 ppm.
In BBCT, the five aromatic protons on ring A appear at 7.8 ppm while the five protons on ring
B have their peak centered at 7.5 ppm. The CH2-S peak appeared as a singlet at 2.5 ppm.
The 13CNMR data of the ligands are much as expected as seen in Table 7. For DBCT,
the ten aromatic carbons on the A and B symmetrical rings appear between 129.271 ppm
and 131.411 ppm. Assignments have been given based on their proximity to the –C=O
substituent and possible shielding effects11. The carbons on the pyridine ring were presented
on three peaks appearing between 131.411 ppm and 133.621 ppm. Appropriate assignments
have been given based on degree of shielding or shielding provided by the hetero nitrogen
and the sulphur atoms attached to the ring.
In the BBCT, nine peaks were observed. The CH2 carbon peak appeared at 40.000 ppm.
The carbon atoms on both aromatic rings showed some level of chemical equivalence hence
assignments were done taking cognizance of this. C6 and C9 were distinct based on their
nearness to C=O and S-CH2 respectively and this showed relatively downfield peaks at
133.482 ppm and 133.328 ppm respectively.
Table 6. 1H NMR data of ligands (ppm)
DBCT
Peaks, ppm
7.95 (10 H, m) aromatic protons on the side rings.
Assignment
7.52 (1 H,s)
7.6 (4 H,s)
proton in the middle pyridine ring.
protons on the two amino groups of the pyridine ring.
BBCT
Peaks, ppm
Assignment
7.8 (5 H,m)
7.5 (5 H,m)
2.5 (2 H,s)
Aromatic protons on ring A
Aromatic protons on ring B
CH2 – S Protons.

238
P. O. UKOHA et al.
Table 7. 13C NMR data of the ligands
The ligand, DBCT
O
9
O
S
S
10
8
14
15
`7
13
1
6
11
`12
16
17
NH219
H2N
5
N
2
18
3
4
B
A
Peaks for DBCT (ppm)
129.271
129.931
Assignments
C1, C15
C2, C16
C3, C17
C4, C18
C5, C19
C6, C14
C9
129.472
129.962
129.986
129.992
131.411
133.581
C8, C10
C11, C12
C7, C13
133.621
168.017
The ligand, BBCT
O
8
10
1
6
9
11
12
2
3
7
S
14
5
13
4
Peaks for BBCT (ppm)
40.0
129.188
Assignment
C8
C2, C11
C1, C10
C3, C12
C4, C13
C5, C10
C9
129.224
129.977
130.011
131.449
133.328
133.482
168.063
C6
C7
Antimicrobial properties
Antimicrobial properties of DBCT, BBCT and their Mn(II) complexes are presented in
Table 8. As shown in the Table, the ligands and their metal complexes did not inhibit the
growth of E. coli strain used in the study. [Cu(DBCT)Cl2] showed activity only on S. aureus
and B. subtilis while [Cu(BBCT)2Cl2] showed some level of activity against S.aureus,
B.subtilis, P.aeruginosa and C.albicans. Also [Mn(BBCT)2(H2O)2]2+ was active against
S.aureus, P.aeruginosa and C.albicans while [Mn(DBCT)Cl2] showed activity only against
B.subtilis. Generally, complexing the metals with the ligands did not show any marked
enhancement of activity of the ligands. The significant exception is [Cu(BBCT)2Cl2] which
has activity against B.subtilis whereas BBCT showed insensitivity to the microorganism.
The results show that the ligands and some of their complexes could be exploited as
potential source of chemotherapeutic agents.

Synthesis, Spectroscopic Characterization
239
Table 8. Antimicrobial properties of DBCT, BBCT and their metal complexes
Mean Inhibition Zone Diameter (IZD) ( sem)*
[Cu
[Cu
[Mn
[Mn(BBCT)2
Microorganism DBCT
BBCT
(DBCT)Cl2] (BBCT)2Cl2] (DBCT)Cl2] (H2O)2]2+
Staphlococus
Aureus (ATCC 16 0.02 20 0.20 12 0.05
14 0.02
14 0.05
11 0.03
0
0
15 0.04
0
25923)
Bacillus Subtilis
13 0.02
0
12 0.02
12 0.03
(ATCC 6633)
Pseudomonas
aeruginosa
10 0.01 11 0.00
0
0
0
0
0
0
12 0.02
0
(ATCC 27853)
Escherichia coli
(ATCC 25922)
Candidas
albicans
(ATCC 90028)
0
0
12 0.04 12 0.05
12 0.04
12 0.02
* mean of three replicates (measured in mm)
Conclusion
Two thiolates and their Mn(II) and Cu(II) complexes have been successfully prepared and
characterized. The complexes presented an octahedral geometry although the copper
complexes were identified as having distorted octahedral geometry. All the complexes were
non-electrolytes except [Mn(BBCT)2(H2O)2]2+ which crystallized as a 2:2 electrolyte. BBCT
coordinate as a bidentate ligand whereas DBCT coordinate as a tetradentate ligand. The
ligands and complexes showed good potential as prospective chemotherapeutic agents.
Acknowledgment
P.O.Ukoha is grateful to Dr. J.O. Igoli of the University of Strathclyde, Scotland, UK for
helping in the running of some spectral data.
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