Coordination compounds of 3d-metal valerates and benzoates with nicotinamide

Article abstract of DOI:10.1134/S107036320709023X

Complexes of iron(II), cobalt(II), nickel(II), copper(II), and zinc valerates and benzoates with nicotinamide were synthesized. The products were characterized by chemical analysis, IR spectroscopy, diffuse reflection spectroscopy, and thermogravimetry.

Full text of DOI:10.1134/S107036320709023X

ISSN 1070-3632, Russian Journal of General Chemistry, 2007, Vol. 77, No. 9, pp. 1635 1642.
Pleiades Publishing, Ltd., 2007.
Original Russian Text
pp. 1564 1571.
T.V. Koksharova, I.S. Gritsenko, I.V. Stoyanova, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 9,
Coordination Compounds of 3d-Metal Valerates and Benzoates
with Nicotinamide
T. V. Koksharovaa, I. S. Gritsenkoa, and I. V. Stoyanovab
a Mechnikov National University,
ul. Dvoryanskaya 2, Odessa, 65026 Ukraine
e-mail: koksharova@farlep.net
b Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine, Odessa, Ukraine
Received November 28, 2006
Abstract Complexes of iron(II), cobalt(II), nickel(II), copper(II), and zinc valerates and benzoates with
nicotinamide were synthesized. The products were characterized by chemical analysis, IR spectroscopy,
diffuse reflection spectroscopy, and thermogravimetry.
DOI: 10.1134/S107036320709023X
Synthesis and study of coordination compounds of
microelements with bioactive organic substances can
be one of promising ways of creating potential highly
effective pharmaceuticals. It is known [1] that co-
ordinated metals are more bioactive and less toxic
than their inorganic salts. Furthermore, a combination
of a microelement and a bioactive organic substance
in the same complex can lead to synergism in their
action. Nicotinamide (vitamin PP) enters into the
composition of two coenzymes (cozymase and co-
dehydrase). The mechanism of their action consists in
redox reactions, whereas the nicotinamide part is
hydrogen carrier [2]. Modeling complicated metallo-
enzymes and metallocoenzymes by fairly simple metal
complexes is a routine experimental approach. To
synthesize and analyze the structures and properties
of coordination compounds of iron(II), cobalt(II),
nickel(II), coppers(II), and zinc valerates and benzo-
ates with nicotinamide (L), we used valeric and ben-
zoic acids as carboxylic acids, sources of carboxylate
anions.
The chemical analysis (Table 1) shows that the me-
tal-to-nicotinamide ratio in the resulting compounds
Table 1. Elemental analyses and colors of products I XIII of the reactions of 3d-metal valerates and benzoates with
nicotinamide
Found, %
Calculated, %
Comp.
no.
Color
Formula
M
N
M
N
I
II
Brown
Pink
Pink
Pink
Pink-lilac
Light green
Light green
Blue
8.3
11.6
9.7
10.1
7.3
10.6
9.1
9.9
16.5
12.1
11.2
12.4
11.7
12.8
10.8
13.8
9.8
14.4
10.1
13.2
9.8
7.1
11.2
9.8
11.1
10.1
C32H28FeN6O7[FeL3(Benz)2]
C44H60Co2N8O12 H2O[CoL2(Val)2]2 H2O]
C28H36CoN6O7[CoL3(Val)2]
C26H22CoN4O6 2H2O[CoL2(Benz)2 2H2O]
C38H34CoN8O8[CoL4(Benz)2]
C22H30N4NiO6 2H2O[NiL2(Val)2 2H2O]
C28H36N6NiO7[NiL3(Val)2]
C26H22N4NiO6 2H2O[NiL2(Benz)2 2H2O]
C16H24CuN2O5[CuL(Val)2]
C22H30CuN4O6[CuL2(Val)2]
C26H22CuN4O6[CuL2(Benz)2]
C22H30N4O6Zn[ZnL2(Val)2]
8.4
11.5
9.4
10.2
7.5
12.7
10.9
13.4
9.6
14.2
10.4
13.4
9.6
III
IV
V
VI
VII
VIII
IX
X
10.9
9.4
10.2
16.5
12.5
11.6
12.7
11.8
Green
7.2
Dark blue
Dark blue
White
11.0
10.2
11.0
10.2
XI
XII
XIII
White
C26H22N4O6Zn[ZnL2(Benz)2]
1635

1636
KOKSHAROVA et al.
depends on the carboxylate anion used. We were
unable to obtain a pure iron(II) valerate, probably
because of hydrolysis. Therefore, the corresponding
complex with nicotinamide was not prepared either,
whereas with the other metals under study we could
prepare nicotinamide complexes both with valerates
and benzoates. Metal benzoates form nicotinamide
complexes of the composition 1:3 with iron(II), 1:2
with nickel(II), copper(II), and zinc(II), and only in
the case of cobalt(II) it was possible to isolate 1:2 and
1:4 complexes. Metal valerates form more diverse
nicotinamide complexes: in addition to the 1:2 com-
position which was obtained with all the metals (ex-
cept for iron), the composition 1:1 is realized with
copper(II) and 1:3, with nickel(II) and cobalt(II). This
suggests that 3d-metal valerates more readily than
benzoates react with nicotinamide. The complexes of
3d-metal valerates and benzoates with nicotinamide
are soluble in water and DMF and slightly poorer
soluble in ethanol.
amide molecules, respectively, as well as two oxygen
atoms of water [4]. A green complex CuL(Val)2 (IX)
consists of binuclear molecules in which two copper
atoms are bound through four bidentate bridging
valerate anions, nicotinamide is bound to copper
through the pyridine nitrogen atom, and the coordina-
tion polyhedron of each copper atom in the 1:1 com-
plex represents a tetragonal pyramid [5]. In a pale blue
complex CuL2(Val)2 (X), the copper atom has a tetra-
gonal bipyramidal coordination due to four oxygen
atoms of two valerate anions and two pyridine nitro-
gen atoms of the nicotinamide ligands, and the va-
lerate anions function as bidentate pseudo-bis-chelate
ligands [6].
Conclusions as to the coordination modes of the
ligands in the coordination polyhedra of compounds
I, III VII, and XI XIII were drawn on the basis of
spectral data. To assign the principal absorption bands
in the IR spectra of nicotinamide and the complexes
(Table 2), we used published data [2, 7, 8]. Owing to
the presence of hydrogen bonds, uncoordinated nico-
tinamide molecules are coordinated in the solid state,
which affects the frequencies of certain bands in the
IR spectra. This effect is most pronounced in the spec-
tra of crystalline amides and less pronounced in the
spectra of crystalline metal complexes with amides in
the absence of coordination of L through the amide
nitrogen atom, as evidenced by spectral and X-ray
diffraction data for a great number of complexes [8].
Therefore, for correct interpretation of coordination-
induced shifts of nicotinamide absorption bands, we
considered it necessary to take the IR spectra of the
The structure of compounds (II, VIII X) was
determined by X-ray diffraction analysis [3 6]. It was
found that [CoL2(Val)2]2 H2O (II) is binuclear with
octahedral coordination of the cobalt atom, nicotin-
amide is monodentate and is bound via the pyridine
nitrogen atom, the valerate anions are present both in
a monodentate and in a bidentate bridging forms, and
the water molecule plays the role of a bridge between
two cobalt atoms [3]. In NiL2(Benz)2 2H2O (VIII),
the octahedral coordination environment of the nickel
atom includes two atoms of oxygen and two atoms of
nitrogen of monodentate benzoate anions and nicotin-
Table 2. IR spectra of nicotinamide (L), 3d-metal valerates and benzoates, and their reaction products I XIII
1
Absorption bands (cm ) of the COO group
1
Comp.
no.
Absorption bands (cm ) of nicotinamide
and caroxylate anions
as(COO )
s(COO )
(COO )
(COO )
L (KBr
tablets)
3376, 3300, 3170 [ (NH)], 3090, 3035, 2970, 2960,
2910, 2890, 2820 [ (CH)], 1687 [ (C=O)], 1627
[ (NH2)], 1580 ( ring), 1380, 1360, 1340 [ (CCH)],
1290, 1250, 1205 [ (CCH), (CCC)], 1160, 1134
[ (NH2), (CCH)], 1030, 1005 ( ring), 890, 835, 760
[ (CC), (CCC)], 702 [ (CCN)ring], 635, 610
[ (CNC)ring], 550 [ (CCN), (CCC)]
L
(Nujol
3350, 3145 [ (NH)], 1665 [ (C=O)], 1610 [ (NH2)],
1585, 1560 ( ring), 1365, 1330 [ (CCH)], 1295, 1195
[ (CCH), (CCC)], 1145, 1120 [ (NH2), (CCH)],
1020, 965 ( ring), 880, 820, 765 [ (CC), (CCC)], 710
[ (CCN)ring], 635, 615 [ (CNC)ring], 595, 500 [ (CCN),
(CCC)]
suspension)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 9 2007

COORDINATION COMPOUNDS OF 3d-METAL VALERATES AND BENZOATES
Table 2. (Contd.)
1637
1
Absorption bands (cm ) of the COO group
1
Comp.
no.
Absorption bands (cm ) of nicotinamide
and caroxylate anions
as(COO )
1601
s(COO )
(COO )
(COO )
21, 3
Fe(Benz)2
3365, 3193 [ (NH)], 3070 [ (CH)], 1683 [ (C=O)],
1407
1405
194
215, 197
2H2O
1567 ( ring), 1201 [ (CCH), (CCC)], 1177 [ (NH2), 1620 sh,
I
(CCH)], 1071, 1027 ( ring), 837, 786 [ (CC),
(CCC)], 718 [ (OCO)], 707 [ (CCN)ring], 675, 626
[ (CNC)ring(L)], 481 (MO), (CH), (CC)
1602
Co(Val)2
2H2O
II
3428 [ (OH)], 3376, 3197 [ (NH)], 2958, 2932, 2872
[ (CH)], 1678 [ (C=O)], 1615 sh [ (NH2)],
1590 sh ( ring), 1380a sh, 1315 [ (CCH), (CH3)],
1290, 1240, 1202 [ (CCH), (CCC)], 1101 [ (NH2),
(CCH)], 1051, 1034 ( ring), 942 [ (CC) (C4H9-)],
831, 790, 757 [ (CC), (CCC)], 720 sh [ (OCO)], 700
[ (CCN)ring], 664, 648 [ (CNC)ring], 595 [ (CCN),
(CCC)], 434 (MO), (CH), (CC)
1568
1413
155
1600 v.s 1411 v.s, 189, 220
34, 65
1380a sh
III
3348, 3187 [ (NH)], 2958, 2932, 2872 [ (CH)], 1680
[ (C=O)], 1590 sh ( ring), 1202 [ (CCH), (CCC)],
1100 [ (NH2), (CCH)], 1050, 1032 ( ring), 831, 789,
756 [ (CC), (CCC)], 735 [ (OCO)], 702 [ (CCN)ring],
647, 626 [ (CNC)ring], 427 (MO), (CH), (CC)
3474 [ (OH)], 3342, 3186 [ (NH)], 3064, 2817
[ (CH)], 1676 [ (C=O)], 1609 [ (NH2)], 1585 ( ring),
1200 [ (CCH), (CCC)], 1139 [ (NH2), (CCH)],
1070, 1053, 1031 ( ring), 820, 742 [ (CC), (CCC)],
730 [ (OCO)], 691 [ (CCN)ring], 677, 649, 639
[ (CNC)ring(L)], 506 [ (CCN), (CCC)], 451, 427
(MO), (CH), (CC)
1602
1423,
1410
179, 192
24, 37
Co(Benz)2
2H2O
1594
1598
1497
1395
97
203
106
IV
V
3372, 3219 [ (NH)], 3068 [ (CH)], 1675 [ (C=O)],
1636 [ (NH2)], 1580 ( ring), 1196 [ (CCH), (CCC)],
1115 [ (NH2), (CCH)], 1068, 1054, 1027 ( ring), 860,
838, 826, 777 [ (CC), (CCC)], 719 [ (OCO)], 699
[ (CCN)ring], 649, 641, 625 [ (CNC)ring(L)], 517
[ (CCN), (CCC)], 452, 437 (MO), (CH), (CC)
3450 [ (OH)], 3357, 3182 [ (NH)], 2959, 2932, 2873
[ (CH)], 1698 [ (C=O)], 1635 [ (NH2)], 1585 sh
1594
1422
172
75
Ni(Val)2
H2O
1568
1603
1417
1396
151
207
56
VI
(
ring), 1202 [ (CCH), (CCC)], 1100 [ (NH2),
(CCH)], 1052, 1034 ( ring), 832, 792, 758 [ (CC),
(CCC)], 730 [ (OCO), 703 [ (CCN)ring], 674, 648
[ (CNC)ring], 440 (MO), (CH), (CC)
VII
3364, 3191 [ (NH)], 2958, 2932, 2871 [ (CH)], 1680
[ (C=O)], 1585 sh ( ring), 1202 [ (CCH), (CCC)],
1108 [ (NH2), (CCH)], 1053, 1032 ( ring), 830, 794,
758 [ (CC), (CCC)], 740 [ (OCO)], 699 [ (CCN)ring],
655, 626 [ (CNC)ring], 520 [ (CCN), (CCC)], 437
(MO), (CH), (CC)
1614
1408,
1390
206, 224
55, 73
Ni(Benz)2
2H2O
3472 [ (OH)], 3397, 3193 [?(NH)], 3068, 2905
[ (CH)], 1693, 1670 [ (C=O)], 1590 sh ( ring), 1202
[ (CCH), (CCC)], 1170, 1135 [ (NH2), (CCH)],
1070, 1053 ( ring), 855, 840, 795, 755 [ (CC),
1596
1498
98
204
1602 v.s 1398 v.s
106
VIII
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 9 2007

1638
KOKSHAROVA et al.
Table 2. (Contd.)
1
Absorption bands (cm ) of the COO group
1
Comp.
no.
Absorption bands (cm ) of nicotinamide
and caroxylate anions
as(COO )
s(COO )
(COO )
(COO )
Ni(Benz)2
2H2O
(CCC)], 726 [ (OCO)], 698 [ (CCN)ring], 677, 652
[ (CNC)ring(L)], 518 [ (CCN), (CCC)]
VIII
Cu(Val)2
2H2O
IX
3395, 3326, 3190 [ (NH)], 3085, 2960, 2940, 2875,
2780 [ (CH)], 1695 [ (C=O)], 1605 sh [ (NH2)],
1595 sh ( ring), 1385, 1330 [ (CCH), (CH3)], 1305,
1250, 1208 [ (CCH), (CCC)], 1160, 1115 [ (NH2),
(CCH)], 1060, 1045 ( ring), 945 [ (CC) (C4H9-)],
870, 840, 800, 760 [ (CC), (CCC)], 725 [ (OCO)],
702 [ (CCN)ring], 650, 615 [ (CNC)ring], 530 [ (CCN),
(CCC)], 430 (MO), (CH), (CC)
1587
1417
170
180
1600 v.s 1420 v.s
10
X
3368, 3267, 3197 [ (NH)], 3050, 2960, 2935, 2872,
2786 [ (CH)], 1687 [ (C=O)], 1624 [ (NH2)], 1590
1602
1400
202
32
(
ring), 1350, 1330 [ (CCH), (CH3)], 1305, 1270,
1203 [ (CCH), (CCC)], 1130, 1124 [ (NH2), (CCH)],
1059, 1030, 970 ( ring), 936 [ (CC) (C4H9-)], 865,
831, 761 [ (CC), (CCC)], 720 [ (OCO)], 703
[ (CCN)ring], 646, 626 [ (CNC)ring], 512 [ (CCN),
(CCC)], 444, 412 (MO), (CH), (CC)
Cu(Benz)2
2H2O
3374, 3216 [ (NH)], 3071, 2779 [ (CH)],
1673 [ (C=O)], 1637 [ (NH2)], 1585 ( ring), 1195
[ (CCH), (CCC)], 1116 [ (NH2), (CCH)], 1068,
1027 ( ring), 856, 838, 777 [ (CC), (CCC)], 718
1591
1598
1434
1395
157
203
46
31
35
XI
[ (OCO),
697 ( (CCN)ring], 658, 641, 626
[ (CNC)ring(L)], 532 [ (CCN), (CCC)], 443 (MO),
(CH), (CC)
Zn(Val)2
2H2O
XII
3370, 3173 [ (NH)], 2959, 2930, 2863, 2781 [ (CH)],
1705 [ (C=O)], 1624 [ (NH2)], 1596 ( ring), 1204
[ (CCH), (CCC)], 1137, 1102 [ (NH2), (CCH)],
1056, 1026 ( ring), 830, 797, 784, 765 [ (CC),
(CCC)], 712 [ (OCO)], 691[ (CCN)ring], 659, 626,
606 [ (CNC)ring], 524 [ (CCN), (CCC)], 430 (MO),
(CH), (CC)
575
1609
1395
1398
180
211
Zn(Benz)2
2H2O
3369, 3178 [ (NH)], 1702 [ (C=O)], 1630 [ (NH2)],
1570 ( ring), 1200 [ (CCH), (CCC)], 1138 [ (NH2),
(CCH)], 1070, 1053 ( ring), 843, 836, 793, 759
[ (CC), (CCC)], 720 [ (OCO)], 691 [ (CCN)ring],
675, 650, 625 [ (CNC)ring(L)], 575 [ (CCN), (CCC)],
458, 430 (MO), (CH), (CC)
1599
1600
1417
1383
182
217
XIII
a
Both the nicotinamide and valerate anions contribute to the absorption band.
ligand both as KBr tablets and as suspension in Nujol.
The IR spectra of suspensions of the starting 3d-metal
carboxylates and their nicotinamide complexes in
Nujol are poorly informative, as the absorption bands
of Nujol and the carboxy group partially overlap.
The absorption frequencies of nicotinamide change
similarly in going to all the complexes synthesized.
The (NH) frequencies in the IR spectra of the com-
plexes are higher than in the spectrum of free nicotin-
amide in Nujol and sometimes than in the spectrum
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COORDINATION COMPOUNDS OF 3d-METAL VALERATES AND BENZOATES
1639
of the solid sample. The (C=O) frequency (amide
I) also increases for complexes in comparison with
Table 3. Diffuse reflection spectra of nicotinamide com-
plexes of 3d-metal valerates and benzoates I XI
the spectrum of the ligand suspended in Nujol. The
1
bands both near 1600 and near 1000 cm are
Comp. no.
max, nm
1369
Assignment
ring
shifted to high frequencies in comparison with free
nicotinamide. The similarity in the behavior of the
absoption bands of nicotinamide in going to com-
pounds II, VIII X in which the monodentate co-
ordination through the pyridine nitrogen atom is
proved by means of X-ray diffraction, on the one hand,
and to compounds I, III VII, XI XIII, on the other,
suggests that nicotinamide in all the synthesized
complexes acts as a monodentate ligand coordinated
through the pyridine nitrogen atom.
I
5T2g
5Eg
II
493
1138
491
1138
500
1131
497
638
1138
626
1058
627
1048
626
1043
681
4T1g(F)
4T1g(F)
4T1g(F)
4T1g(F)
4T1g(F)
4T1g(F)
4T1g(F)
4T1g(F)
4T1g(F)
3A2g
4T1g(P)
4T2g
III
IV
V
4T1g(P)
4T2g
4T1g(P)
4T2g
4T1g(P)
4A2g
4T2g
Carboxylate anions generally coordinate to metal
ions in a bidentate mode. Detachment of a proton
from the carboxy group in a carboxylic acid makes
the oxygen atoms equivalent. Carbonyl absorption
bands disappear from the IR spectra and two new
VI
3T1g
3A2g
3T2g
3T1g
3T2g
3T1g
3T2g
VII
VIII
3A2g
3A2g
3A2g
1
bands appear in the region of 1550 1610 cm and
3A2g
1
1300 1400 cm (antisymmetric and symmetric vibra-
IX
X
XI
tions of the COO group) [9]. As the bond equivalence
is violated due to formation of mixed-ligand coordina-
tion compounds, the difference between as(COO )
and s(COO ) should increase. Examination of such
differences (Table 2) for the starting carboxylates and
their complexes with nicotinamide shows that all the
synthesized compounds can be separated into three
595
630
pectively]. Thus, we can assume that the carboxylate
anions in complexes IV VI are monodentate, in com-
plexes XI XIII, bidentate, and in complexes I, III,
and VII, both monodentate and bidentate. Hence, the
coordination mode of carboxylate anions depends on
the nature of the complex-forming metal and anion,
and the stoichiometry of the resulting compound.
With copper(II) and zinc(II), all carboxylate anions
are bidentate; in cobalt(II) benzoate anions, they are
monodentate, and in valerate anions, monodentate
coordination is realized simultaneously with bidentate
coordination; in 1:2 nickel(II) complexes, both car-
boxylate anions are monodentate, and in the 1:3
complexes, both types of anion coordination take
place. Thus, monodentate coordination is more charac-
teristic for benzoate anions than for valerate anions;
in all complexes with a 1:3 metal-to-ligand ratio,
mixed anion coordination is observed.
groups in terms of this difference. In the first group of
1
complexes,
(COO ) is 56 106 cm , in the second,
1
46 cm , and in the third, the s(COO ) band is split
into a doublet [in the spectrum of the iron(II) complex
the as(COO ) band is split]. It is known [10] that the
largest difference between s(COO ) and as(COO )
corresponds to monodentate coordination of car-
boxylate anions. Hence, in the complexes with large
(COO ) values, the equivalence of carboxyl
oxygen atoms is violated to formation of mixed-ligand
complexes, i.e. the carboxylate anions enter into the
inner sphere of these coordination compounds as
monodentate ligands. As to the compounds with
modest
there the carboxy groups remain bidentate. The band
splitting, i.e. the observation of two (COO )
(COO ) values, we should assume that
values for the same compound, suggests that it contains
differently coordinated carboxylate anions: both
monodentate and bidentate.
The (OH) bands of water molecules in the IR
spectra of the obtained compounds lay in the region
characteristic for stretching O H vibrations in aqua
complexes [9].
The above assumptions agree with the X-ray dif-
fraction data: The carboxylate anion in complex VIII
coordinates as a monodentate ligand [
(COO )
The diffuse reflection spectra are presented in
Table 3. The positions of the bands suggest that
iron(II), cobalt(II), and nickel(II) compounds are
octahedral and CuL2(Benz)2 (XI) has a tetragonal
bipyramidal structure [11].
1
106 cm ], those in complexes IX and X are bidentate
1
[
(COO ) 10 and 32 cm , respectively], and those
in complex II act as both monodentate and bidentate
1
bridging ligands [
(COO ) 65 and 34 cm , res-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 9 2007

1640
KOKSHAROVA et al.
Table 4. Results of thermal analysis of nicotinamide complexes of 3d-metal valerates and benzoates
Endo effects
C
Exo effects
C
Comp. no.
Total weight loss, %
t,
m, %
24.0
t,
m, %
III
260 330 (298)
82 140 (90)
330 442 (418)
310 400 (350)
51.7
8.1
87.6
55.7
140 260 (230)
155 178 (163)
70 103 (90)
39.4
III
IV
178 330 (289)
250 460 (415)
75.4
41.0
82.3
82.5
4.5
28.6
14.6
7.5
15.4
2.9
210 250 (230)
82 180 (130)
230 252 (240)
82 162 (135)
162 202 (180)
255 300 (290)
128 180 (155)
238 300 (270)
93 170 (140)
173 210 (180)
V
310 400 (360)
56.8
90.0
83.7
VI
56.9
VII
350 450 (400)
6.0
64.8
57.4
17.9
VIII
IX
300 400 (350)
210 262 (235)
262 410 (350)
430 500 (480)
205 280 (240)
330 400 (350)
45.0
41.2
19.6
9.8
70.1
14.8
82.2
80.4
X
XI
160 205 (175)
178 200 (190)
200 280 (245)
118 150 (130)
230 300 (263)
135 160 (144)
160 240 (192)
240 350 (288)
75.0
79.2
14.5
33.0
XII
300 400 (350)
400 480 (440)
9.8
2.2
63.8
78.2
42.9
1.4
3.8
XIII
69.9
The thermogravimetric data for the synthesized
compounds are given in Table 4. In all the valerate
complexes of 3d metals with nicotinamide, except for
NiL2(Val)2 2H2O (VI), the first effect with a
maximum at 90 180 C is endothermic and not accom-
panied by weight loss.
valerate complexes with nicotinamide is attributable
to the following. The X-ray diffraction analysis
showed that the general configuration of CuL2(Val)2
is similar to the configuration of half the [CuL(Val)2]2
molecule. As a blue CuL2(Val)2 is heated to the
temperature of the first endo effect, it turns to a green
[CuL(Val)2]2. Hence, the temperature of this endo
effect corresponds to bond cleavage between the
copper atom and the second coordinated nicotinamide
molecule; simultaneously chelated valerate anions
transform to bridging anions, i.e. one of the oxygen
atoms in each valerate anion (weaker bound to copper)
passes from its own copper atom to the neighboring
atom, which corresponds to formation of bridges.
Thus, the endo effect at 160 205 C (with a maximum
at 175 C) for CuL2(Val)2 can be assigned to the
following process.
Obviously, it should be assigned to melting. The
fact that complex VI is an exception may well be
caused by the presence of a weakly bound water in it.
The benzoate complexes decompose without melting.
Their thermal stability decreases in the following
order depending on the nature of the complex-forming
metal: Fe2+ > Cu2+ > Zn2+ > Ni2+ > Co2+.
Except for the cobalt compounds, the benzoate
complexes are more thermally stable than the valerate
ones. The dependence of the thermal stability on the
stoichometry of the compounds is traced also. In all
MLn(RCOO)2 compounds with the same M(RCOO)2
salt and two different n values, except for the copper
complexes, compounds with higher n values are more
stable. The reverse dependence for the copper(II)
2CuL2(Val)2
[CuL(Val)2]2 + 2L.
Our research suggests that coordination compounds
I XIII have the following structures.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 9 2007

COORDINATION COMPOUNDS OF 3d-METAL VALERATES AND BENZOATES
1641
O
O
C
C
C
C
C
R
C
H2
O
H2N
NH2
NH2
O
C
N
O Co
N
N
Co
N
O
O
N
O
O
R
O
R
O
O
R
C
O
M
R
C
O
N
O
N
C
R
O
NH2
O
O
C
H2N
C
C
H2N
O
NH2
II
R = C4H9 (II) [3].
I, III, VII
M = Fe, R = C6H5 (I); M = Co, R = C4H9 (III); M = Ni,
R = C4H9 (VII).
O
O
O
R
O
C
C
NH2
C
C
NH2
N
N
N
H2N
OH2
N
O
O
O
Co
C
O
O
C
N
M
R
NH2
O
O
H2O
H2N
O
N
C
C
C
H2N
C
R
O
O
V
IV, VI, VIII
M = Co, R = C6H5 (IV); M = Ni, R = C4H9 (VI), R =
C6H5 (VIII) [4].
R = C6H5 (V).
R
C
O
R
R
C
NH2
O
C
O
C
C
O
O
O
O
C
NH2
H2N
M
N
N
O
O
Cu
O
O
O
Cu
O
N
N
C
O
H2N
O
O
C
R
C
C
R
X XIII
R
IX
M = Cu, R = C4H9 (X) [6], C6H5 (XI); M = Zn, R = C4H9
(XII), C6H5 (XIII).
R= C4H9 (IX) [5].
EXPERIMENTAL
Analytical grade iron(II), cobalt(II), nickel(II), cop-
per(II), and zinc chlorides, valeric and benzoic acids,
and nicotinamide were used in the work.
The IR spectra were recorded on a Perkin Elmer
Spectrum BX-II-FT-IR device in KBr. The diffuse
reflection spectra were recorded on a Perkin Elmer
Analysis for metals was performed by complexo-
metry [12] and for nitrogen, by Dumas [13].
Lambda-9 spectrophotometer against MgO (
MgO
100%). Thermal analysis was performed on a Paulik
Paulik Erdey derivatograph in air, heating rate
10 deg min .
Complexes I, V, VII, and X. Nicotinamide
(0.61 g) was dissolved in 5 ml of ethanol. Dry iron(II),
cobalt(II), nickel(II), or copper(II) valerate or benzoate
1
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 9 2007

1642
KOKSHAROVA et al.
(0.00125 mol) was added in portions with stirring.
The resulting mixture was stirred for 1 h. The pre-
cipitate that formed was filtered off, washed with a
little ethanol, and dried in a desiccator over CaCl2 to
constant weight.
Abstracts of Papers, XV Int. Conf. Physical Methods
in Coordination and Supramolecular Chemistry,
Chisinau, Moldova, 2006, p. 91.
4. Koksharova, T.V., Sadikov, G.G., Antsyshkina, A.S.,
Gritsenko, I.S., Sergienko, V.S., and Egorova, O.A.,
Zh. Neorg. Khim., 2006, vol. 51, no. 6, p. 966.
Complex III. Nicotinamide (0.61 g) was dissolved
in 5 ml of ethanol. Dry Co(C4H9COO)2 2H2O was
added in portions with stirring. The resulting mixture
was stirred for 15 min, and in this time the carboxy-
late dissolved completely. The solution was left for
spontaneous ethanol evaporation. The precipitate was
filtered off, washed with a little ethanol, and dried in
a desiccator over CaCl2 to constant weight.
5. Antsyshkina, A.S., Koksharova, T.V., Sadikov, G.G.,
Gritsenko, I.S., Sergienko, V.S., and Egorova, O.A.,
Zh. Neorg. Khim., 2006, vol. 51, no. 6, p. 972.
6. Antsyshkina, A.S., Sadikov, G.G., Koksharova, T.V.,
Gritsenko, I.S., and Sergienko, V.S., Zh. Neorg. Khim.,
2006, vol. 51, no. 10, p. 1671.
7. Tsivadze A.J., Tsintsadze G.V., Haritonov J.J., and
Gverdtsiteli L.V., Zh. Neorg. Khim., 1978, vol. 23,
no. 2, p. 447.
Complexes II, IV, VI, VIII, IX, and XI XIII.
Nicotinamide (0.61 g) was dissolved in 5 ml of
ethanol. Dry cobalt(II), nickel(II), copper(II), or zinc
valerate or benzoate (0.0025 mol) was added in por-
tions with stirring. The resulting mixture was stirred
for 1 h, the precipitate that formed was filtered off,
washed with a little ethanol, and dried in a desiccator
over CaCl2 to constant weight.
8. Tsintsadze, G.V., Shavtvaladze, M.V., and Tsivad-
ze, A.J., Koord. Khim., 1990, vol. 16, no. 12, p. 1666.
9. Kukushkin, Yu.N., Khimiya koordinatsionnykh soe-
dinenii (Chemistry of Coordination Compounds),
Moscow: Vysshaya Shkola, 1985, p. 180.
10. Nakamoto, K., Infrared and Raman Spectra of In-
organic and Coordination Compounds, New York:
Wiley, 1986.
REFERENCES
1. Salikhodzhaev, Z., Shabilalov, A.A., Unuskhodzha-
ev, A.N., Seifullin, F.Kh., and Sadykova, N.D., Khim.
Farm. Zh., 1989, vol. 23, no. 3, p. 296.
11. Lever, A.B.P., Inorganic Electronic Spectroscopy,
Amsterdam: Elsevier, 1984.
12. Schwarzenbach, G. and Flaschka, H., Die Komplexo-
metrishe Titration, Stuttgart: Enke, 1965.
2. Shabilalov, A.A., Borisova, N.N., and Azizov, M.A.,
Koord. Khim., 1987, vol. 13, no. 9, p. 1227.
13. Klimova, V.A., Osnovnye mikrometody analiza or-
ganicheskikh soedinenii (Main Micromethods of
Organic Analysis), Moscow: Khimiya, 1975.
3. Antsyshkina, A.S., Koksharova, T.V., Sadikov, G.G.,
Sergienko, V.S., Gritsenko, I.S., and Egorova, O.A.,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 9 2007