Complexation of d-metal glycinates and glycylglycinates with 4-phenylthiosemicarbazide

Article abstract of DOI:10.1007/s11176-005-0483-8

The complexation of cobalt(III), nickel(II), copper(II), and zinc(II) glycinates and glycylglycinates with 4-phenylthiosemicarbazide was studied. 2005 Pleiades Publishing, Inc.

Full text of DOI:10.1007/s11176-005-0483-8

Russian Journal of General Chemistry, Vol. 75, No. 10, 2005, pp. 1659 1663. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 10, 2005,
pp. 1737 1742.
Original Russian Text Copyright
2005 by Koksharova.
Complexation of d-Metal Glycinates and Glycylglycinates
with 4-Phenylthiosemicarbazide
T. V. Koksharova
Mechnikov National University, Odessa, Ukraine
Received November 11, 2004
Abstract The complexation of cobalt(III), nickel(II), copper(II), and zinc(II) glycinates and glycylgly-
cinates with 4-phenylthiosemicarbazide was studied.
Mixed-ligand 3d-metal complexes containing gly-
cine recently attracted much researchers’ attention
[1 4]. The complexation of 3d-metal glycinates and
glycylglycinates with thiosemicarbazide was studied
in [5]; the complexes were isolated and characterized.
Here we report on the complexation of Co(II), Ni(II),
Cu(II), and Zn(II) glycinates and glycylglycinates
with a substituted thiosemicarbazide, 4-phenylthio-
semicarbazide.
a complex with Zn(II) glycylglycinate but does not
form a complex with Zn(II) glycinate.
Thus, we isolated the following coordination com-
pounds with 4-phenylthiosemicarbazide: CoL2(HGG)
(I), Ni(HL)2(HGG)2 (II), Cu(HL)2GG (III), Zn(HL)2
GG (IV), CoL2(Gly) (V), Ni(HL)2(Gly)2 (VI), and
Cu(HL)2(Gly)2 (VII) (HL is 4-phenylthiosemicarba-
zide; H2GG, glycylglycine; and HGly, glycine).
With Cr(III), we failed to isolate pure products of
the reactions of glycylglycinate and glycinate with
4-phenylthiosemicarbazide. Apparently, the reaction
products formed as mixtures with the starting com-
pounds, and these mixtures could not be separated
because of poor solubility of the components. With
Fe(III) and Mn(II), the reactions were accompanied
by redox transformation with decomposition of the
ligands.
Chemical analysis shows that cobalt(III) glycylgly-
cinate and glycinate form with thiosemicarbazide and
4-phenylthiosemicarbazide the compounds of similar
stoichiometry: cobalt : deprotonated thiosemicarba-
zide : amino acid residue = 1 : 2 : 1; the only differ-
ence is that the glycylglycinate complex with unsub-
stituted thiosemicarbazide is hydrated. Apparently,
with Co(III) the deprotonation of thiosemicarbazides
is the only way to avoid steric hindrance that would
arise in the coordination of three neutral thiosemicar-
bazide molecules and binding of counterions neutra-
lizing the charge of the complex.
The X-ray diffraction patterns show that the iso-
lated complexes are individual compounds. Below we
giev as an example the calculated interplanar spacings
(d, ) and reflection intensities (I/I0) for the starting
copper(II) glycylglycinate Cu(GG) 3H2O, complex
III obtained from it, starting nickel(II) glycinate, and
complex VI obtained from it.
Nickel(II) and copper(II) glycylglycinates and gly-
cinates form with 4-phenylthiosemicarbazide 1 : 2
complexes; the similar complex is formed with Zn(II)
glycylglycinate. In this respect, the pattern is different
from that observed with unsubstituted thiosemicarba-
zide. As shown in [5], unsubstituted thiosemicarba-
zide forms with Ni(II) glycylglycinate and glycinate
the same complex with deprotonated thiosemicarba-
zide, containing no amino acid fragments. With Cu(II)
glycylglycinate, thiosemicarbazide gives a 1:2 com-
plex in which one of the coordinated thiosemicarba-
zide molecules is deprotonated. With Cu(II) glycinate,
thiosemicarbazide forms a compound containing one
deprotonated semicarbazide ligand and one glycinate
anion. With Zn(II), we obtained thiosemicarbazide
complexes neither with glycylglycinate nor with
glycinate, whereas 4-phenylthiosemicarbazide forms
Cu(GG) 3H2O: 8.111 (25); 5.56 (16); 2.776 (100);
1.970 (63); 1.61 (22); 1.25 (25).
Complex III: 3.858 (100); 3.230 (90); 2.594 (40);
1.544 (45); 1.527 (35).
Ni(Gly)2 2H2O: 6.566 (8); 3.133 (6); 3.126 (25);
2.832 (100); 2.200 (11); 1.992 (25); 1.624 (7); 1.409
(8); 1.259 (12).
Complex VI: 11.790 (100); 6.175 (16); 5.493 (21);
5.155 (34); 4.647 (11); 4.126 (44); 3.938 (25); 3.565
(51); 3.317 (15); 2.808 (12); 2.524 (11); 1.992 (7).
For all the complexes I VII, the thioamide II band
1
[4-phenylthiosemicarbazide (HL), 1285 cm ; com-
1070-3632/05/7510-1659 2005 Pleiades Publishing, Inc.

1660
KOKSHAROVA
1
plexes, 1310 1350 cm ] is shifted toward higher
frequencies without changes in the intensity. The fre-
most informative are the stretching vibration frequen-
cies of the carboxy group. These frequencies are the
most sensitive to the strength of the metal oxygen
interaction [9]. As the extent of the nonequivalence of
the C O bonds increases, the difference between the
as(CO) and s(CO) frequencies should increase. The
as(COO ) and s(COO ) frequencies are, respective-
1
quency of the thioamide IV band (HL, 738 cm ;
1
complexes, 692 705 cm ) decreases. The thioamide I
1
1
band (HL, 1522 cm ; complexes, 1532 1546 cm ) is
shifted toward higher frequencies and decreases in the
intensity. For the thioamide III bands (HL, 972 and
914 cm ; complexes, 945 995 and 901 975 cm ),
the decrease in the intensity is still more pronounced.
Such trends are typical of bidentate S,N-coordination
of the ligand [6].
1
1
1
ly, 1598 and 1408 cm for Co(Gly)3 2H2O, 1595
1
and 1400 cm for Ni(Gly)2 2H2O, and 1608 and
1
1402 cm for Cu(Gly)2 H2O; for the complexes of
glycinates with 4-phenylthiosemicarbazide, these fre-
quencies are within the ranges 1595 1605 and 1400
Since the thioamide IV band is virtually exclusive-
ly due to (CS) vibrations, a decrease in its frequency
is associated with a decrease in the multiplicity of the
C S bond and characterizes the strength of the M S
bond. Hence, apparently, the stronger the decrease in
the thioamide IV frequency, the stronger the metal
sulfur bond in the complex cation. Thus, the strength
of the metal thiosemicarbazide bond can be quantita-
tively characterized by (thioamide IV). Comparison
of this parameter for complexes of 3d-metal glycinates
and glycylglycinates with unsubstituted thiosemicar-
bazide and with 4-phenylthiosemicarbazide of similar
1
1450 cm . For the complex CoL2(Gly),
(COO )
is somewhat larger than for the initial glycinate; for
Ni(HL)2(Gly)2, it is appreciably smaller, and for
Cu(HL)2(Gly)2, slightly smaller than for the initial
glycinates. This fact suggests that, in the Co(III) com-
plex, the glycinate anion remains in the inner coordi-
nation sphere of the complex and preserves its initial
bidentate coordination; in the Ni(II) complex, the
glycinate anion is displaced from the inner sphere; and
in the Cu(II) complex, the glycinate anion remains in
the inner sphere but becomes monodentate. The as-
sumption that
(COO ) decreases on displacement
compositions shows that
(thioamide IV) for the
of the anion from the inner sphere can be confirmed
as follows. Previously [10, 11] we prepared coordina-
tion compounds of Ni(II) carboxylates with unsubsti-
tuted thiosemicarbazide and of Cu(II) carboxylates
with 1-phenylthiosemicarbazide. For the compounds
that were sufficiently soluble, we measured the molar
electrolytic conductivity in DMF. We found that only
the complex of nickel(II) phthalate with thiosemicar-
bazide was an electrolyte, and specifically for this
complexes with the unsubstituted ligand is larger than
for those with the phenyl derivative. Thus, the phenyl
substituent appreciably decreases the strength of the
metal thiosemicarbazide bond. This trend may be
caused by the electron-withdrawing effect of the phen-
yl substituent on the S atom in the ligand molecule.
The thioamide IV band clearly depends on the
metal cation. For both glycinate and glycylglycinate
complexes of 4-phenylthiosemicarbazide,
(thioam-
complex
(COO ) decreased, whereas for the non-
ide IV) decreases in the order Cu2+ > Ni2+ Co3+
>
1
.
electrolytes it increased by 0 to 125 cm . For the
glycylglycinate anions, we could not reveal a correla-
tion between (COO ) and coordination mode (inner
or outer sphere), because of the lack of pure as(CO)
band; however, the similarity of the stoichiometry,
diffuse reflection spectra, and thermal properties sug-
gests that the glycylglycinate complexes obey the
same relationships as the glycinate complexes.
Zn2+ This series coincides with that observed previ-
ously with the complexes of unsibstituted thiosemicar-
bazide and with published data on stabilities of sul-
fides, Dithizonates, and thiourea complexes [7].
Analysis of a large set of data on (thioamide IV)
for complexes of unsubstituted thiosemicarbazide con-
taining various anions [8] shows that the strength of
the metal thiosemicarbazide bond depends on the
strength of the metal acido ligand bond: The stronger
the bond with the acido ligand, the weaker the bond
with thiosemicarbazide. For the unsubstituted thio-
semicarbazide, the strength of the metal ligand bond
is higher in glycylglycinates than in glycinates. The
same trend is preserved with 4-phenylthiosemicarba-
zide. Hence, glycinate forms stronger bonds with the
metals than glycylglycinate.
The absorption bands of the glycylglycinate anion
in the IR spectra were assigned according to [12].
The IR spectra of complexes of glycylglycinates with
4-phenylthiosemicarbazide contain no (C=O) absorp-
1
tion bands at 1700 1710 cm , characteristic of the
nondissociated carboxy groups. The bands at 1660
1
1590 cm are due to amide I + (NH2) + as(COO )
1
vibrations; at 1440 1405 cm , to amide II vibrations;
1
and at 1407 1378 cm , to s(COO ) vibrations.
Like other amino acids, glycine forms chelates with
metal ions, coordinating through the deprotonated
carboxy group and the donor amino group. In the
vibration spectra of amino acids and their salts, the
For the starting glycylglycinates, they are observed,
1
respectively, at 1614, 1440, and 1392 cm for
1
NaCo(GG)2 2H2O; at 1606, 1440, and 1394 cm for
1
Ni(HGG)2 2H2O; at 1641, 1629, 1405, and 1378 cm
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COMPLEXATION OF d-METAL GLYCINATES AND GLYCYLGLYCINATES
1661
for Cu(GG) 3H2O; and at 1660, 1610, 1440, and
1395 cm for Zn(HGG)2 2H2O. The complexity of
Table 1. Diffuse reflection spectra of complexes of
3d-metal glycinates and glycylglycinates with 4-phenyl-
thiosemicarbazide
1
the structures of even the initial glycylglycinates con-
taining no thiosemicarbazide prevents accurate empir-
ical assignment of the bands, especially of those below
Comp.
no.
,
Comp.
no.
,
max
nm
max
nm
Assignment
1
1400 cm . Strong hydrogen bonds in peptides com-
plicate interpretation of the band shifts upon metal
coordination, because of the concomitant changes in
the extent and nature of hydrogen bonding. The poten-
tial donor atoms of the coordinated dipeptides are the
terminal NH2 group, one or both oxygen atoms of the
carboxy group, or oxygen or nitrogen atom of the
peptide group. The stretching and bending vibration
bands of the N H bonds are poorly informative for
interpretation of the bonding, as such bonds are pres-
ent both in 4-phenylthiosemicarbazide and in glycyl-
glycine.
I
330
410
580
2116
1100
V
300
410
584
2116
700, 1136
1A1g
1A1g
3T1
>
>
>
1T2
1T1
II
III
VI
3T1(P)
3A2
3T1
>
VII
Table 2. Thermogravimetric data for complexes of
3d-metal glycinates and glycylglycinates with 4-phenyl-
thiosemicarbazide
The diffuse reflection spectra (Table 1) suggest the
octahedral structure for the Co(III) compounds, the
cis-distorted octahedral structure for the Cu(II) com-
pounds, and the tetrahedral structure for the Ni(II)
compounds [13]. For each metal, the diffuse reflection
spectra of the glycylglycinate and glycinate complexes
are similar in the shape and position of bands. The
temperatures at which the 4-phenylthiosemicarbazide
complexes start to decompose are also close for
the complexes of a given metal with both anions
(Table 2). Apparently, this may be due to the fact that
the first step of the thermolysis involves dissociation
of the metal 4-phenylthiosemicarbazide bonds. The
DTA curves of the majority of complexes exhibit exo-
effects only, except the first effect for IV and the
second effect for VII, which are endothermic. This
fact distinguishes the 4-phenylthiosemicarbazide com-
plexes of 3d metal with the examined anions from the
related compounds with unsubstituted thiosemicarba-
zide, which always showed one or several endoeffects
in the DTA curves. This distinction is apparently as-
sociated with the high heat of combustion of the ben-
zene ring present in the ligand molecule.
Exoeffects
Comp.
no.
Total weight
loss, %
T,
C
m, %
I
110 260 (170)
260 435 (370)
200 280 (250)
100 200 (150)
200 290 (225)
175 205
350 410 (390)
105 210 (175)
210 380 (250)
380 450 (430)
235 285 (270)
285 440 (400)
450 520 (500)
95 200 (135)
255 350 (300)
31.0
16.6
33.5
13.5
22.3
7.4
63.3
II
III
46.8
42.0
IVa
V
50.3
60.9
4.1
20.1
24.7
5.2
30.4
20.9
8.4
VI
75.6
48.4
VIIb
18.0
12.0
a
Endoeffect: 75 175 (105) C, m 19.9%.
Endoeffect: 200 255 (230) C, m 16.3%.
b
Cu(Gly) + 2HL
Cu(HL) (Gly) ,
(7)
Our results suggest that the interaction in the exam-
ined systems follows Eqs. (1) (7):
2
2
2
VII
The structures of the complexes synthesized are,
NaCo(GG)2 + 2HL
Ni(HGG)2 + 2HL
Cu(GG) + 2HL
CoL2(HGG) + NaHGG, (1)
apparently, as follows:
H2N
I
H
N
Ni(HL)2(HGG)2,
(2)
(3)
N
II
Cu(HL)2GG,
III
S
Co
Zn(HGG)2 +2 HL
Zn(HL)2GG + H2GG, (4)
O
O
IV
S
Co(Gly)3 + 2HL
Ni(Gly)2 + 2HL
CoL2(Gly) + 2HGly,
(5)
(6)
NH
O
NH2
N
H
V
N
H2N
Ni(HL)2(Gly)2,
VI
I
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 10 2005

1662
KOKSHAROVA
H
N
H
N
H
N
H
N
H2N
H2N
O
O
O
S
S
O
Ni2+
Cu
NH2
H2N
2HN
O
O
S
S
O
NH2
NH2
NH2
N
H
N
H
N
N
H
H
II
VII
Comparison of the results of this study with the
data on the related complexes of unsubstituted thio-
semicarbazide [5] shows that introduction of the
phenyl substituent into the thiosemicarbazide mole-
cule weakens the tendency of the ligand to deproto-
nate in the course of the complexation.
H
N
H
N
H2N
S
M
O
O
N
EXPERIMENTAL
S
NH2
N
H
The IR spectra were recorded on a Perkin Elmer
Spectrum BX-II-FT-IR spectrometer; samples were
pelletized with KBr. The diffuse reflection spectra
were taken on a Perkin Elmer Lambda-9 UV-Vis-NIR
spectrophotometer.
N
H
O
NH2
III, IV
M = Cu2+ (III), Zn2+ (IV).
The thermogravigrams were measured with a Pau-
lik Paulik Erdey derivatograph in air at a heating rate
H
1
of 10 deg min .
N
N
Cobalt(II), nickel(II), copper(II), and zinc(II) chlo-
rides, glycine, glycylglycine, and 4-phenylthiosemi-
carbazide were of analytically pure grade.
H2N
S
Co
Analysis for metals was performed by complexo-
metric titration [14]; for S, by the Schoeniger method
(gravimetrically, in the form of BaSO4) [15]; and for
N, by the Dumas method [15]. The X-ray diffraction
patterns were taken on a URS-50-IM diffractometer
with an iron anode (voltage 35 kV, slits 0.5 0.5
O
O
S
NH2
NH2
N
H
N
V
1
0.5 mm, scanning rate 1 deg min ).
Complexes I and V. 4-Phenylthiosemicarbazide
(0.835 g) was dissolved with heating in 25 ml of
ethanol, and 0.0017 mol of anhydrous cobalt(III)
glycylglycinate or glycinate was added. The solution
immediately turned brown-red. In the case of glycyl-
glycinate, the mixture was stirred on a magnetic stirrer
until the precipitate became uniformly brown. In the
case of glycinate, the solution was transferred into
a porcelain cup and kept at room temperature until the
solvent was evaporated. Then the precipitates were
filtered on a glass frit, washed with a small amount
of ethanol, and dried in a desiccator over CaCl2 to
constant weight.
H
H
N
N
H2N
S
Ni2+
O
O
2
S
H2N
NH2
N
H
N
H
VI
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 10 2005

COMPLEXATION OF d-METAL GLYCINATES AND GLYCYLGLYCINATES
1663
Complexes II IV, VI, and VII. 4-Phenylthiosemi-
carbazide (0.835 g) was dissolved on heating in 25 ml
of ethanol, and 0.0025 mol of anhydrous copper(II),
nickel(II), or zinc(II) glycylglycinate or glycinate was
added. A precipitate formed immediately; it was fil-
tered off on a glass frit, washed with a small amount
of ethanol, and dried in a desiccator over CaCl2 to
constant weight.
2. Gehad, M.G., Wafaa, H.M., and Abd El-Rahim, M.A.,
Synth. React. Inorg. Metal-Org. Chem., 2002, vol. 32,
no. 8, p. 1501.
3. Adkhis, A., Djebbar, S., Benali-Baitich, O., Kadri, A.,
Khan, M.A., and Bouet, G., Synth. React. Inorg.
Metal-Org. Chem., 2003, vol. 33, no. 1, p. 35.
4. Chang-Tong, Y., Boujemaa, M., Keith, M.S., and
Jagadese, V.J., J. Chem. Soc., Dalton Trans., 2003,
no. 5, p. 880.
1
Compound I. IR spectrum, cm : 3435, 1601,
1405, 1391, 1350, 995, 975, 694. Found, %: Co 10.9;
N 21.1; S 12.0. CoL2(HGG). Calculated, %: Co 11.3;
N 21.5; S 12.3. Compound II. IR spectrum, cm :
5. Koksharova, T.V., Zh. Obshch. Khim., 2004, vol. 74,
no. 10, p. 1644.
1
6. Singh, B., Singh, R., Chaudhary, R.V., and Tha-
kur, K.P., Indian J. Chem., 1973, vol. 11, no. 2,
p. 174.
3437, 3295, 3216, 1591, 1540, 1436, 1404, 1322,
986, 901, 694. Found, %: Ni 9.4; N 21.8; S 10.1.
Ni(HL)2(HGG)2. Calculated, %: Ni 9.0; N 21.4; S 9.8.
7. Babko, A.K. and Pilipenko, A.T., Fotometricheskii
analiz. Obshchie svedeniya i apparatura (Photometric
Analysis. General Information and Apparatus),
Moscow: Khimiya, 1968, p. 305.
1
Compound III. IR spectrum, cm : 3436, 3288, 3055,
1601, 1532, 1435, 1407, 1312, 918, 692. Found, %:
Cu 12.5; N 21.1; S 12.3. Cu(HL)2GG. Calculated, %:
Cu 12.1; N 21.2; S 12.1. Compound IV. IR spectrum,
1
8. Koksharova, T.V., Visn. Odes. Nats. Univ., Khim.,
cm : 3438, 1620, 1546, 1430, 1391, 1310, 934, 696.
2003, vol. 8, issue 4, p. 192.
Found, %: N 21.1; S 12.2; Zn 12.7. Zn(HL)2GG.
9. Nakamoto, K., Morimoto, Y., and Martell, A.E.,
Calculated, %: N 21.2; S 12.1; Zn 12.3. Compound
1
J. Am. Chem. Soc., 1961, vol. 83, no. 22, p. 4528.
V. IR spectrum, cm : 1605, 1545, 1400, 1330, 945,
920, 705. Found, %: Co 12.3; N 21.5; S 14.1.
CoL2(Gly). Calculated, %: Co 12.7; N 21.1; S 13.8.
Compound VI. IR spectrum, cm : 1595, 1540, 1450,
10. Prisyazhnyuk, A.I., Koksharova, T.V., and Vrublev-
skii, A.I., Zh. Obshch. Khim., 1986, vol. 56, no. 2,
p. 309.
1
1330, 920, 705. Found, %: N 21.1; Ni 11.1; S 12.0.
Ni(HL)2(Gly)2. Calculated, %: N 20.7; Ni 10.9; S
11.8. Compound VII. IR spectrum, cm : 1600, 1535,
1400, 1320, 970, 935, 700. Found, %: Cu 12.1; N
20.1; S 11.3. Cu(HL)2(Gly)2. Calculated, %: Cu 11.7;
N 20.5; S 11.7.
11. Koksharova, T.V. and Prisyazhnyuk, A.I., Ukr. Khim.
Zh., 1989, vol. 55, no. 12, p. 1244.
1
12. Bair, M.L. and Larsen, E.M., J. Am. Chem. Soc., 1971,
vol. 93, no. 5, p. 1140.
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Amsterdam: Elsevier, 1984.
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metrische Titration, Stuttgart: Ferdinand Enke, 1965.
15. Klimova, V.A., Osnovnye mikrometody analiza or-
ganicheskikh soedinenii (Main Methods for Organic
Microanalysis), Moscow: Khimiya, 1975.
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