Formation of the heteropolynuclear complex ([NH2(C 4H9)2][Au{S2CN(C4H 9)2}2][CdCl4])n during the chemisorption of gold(III) with cadmium dibutyldithiocarbamate: Structure and thermal properties

Article abstract of DOI:10.1134/S1070328410050064

The chemisorption properties of cadmium dibutyldithiocarbamate with respect to [AuCl₄]^- in 2M HCl solutions are studied. The heterogeneous reaction of gold(III) binding affords the heteropolynuclear compound ([NH₂(C₄H₉)₂][Au{S ₂CN(C₄H₉)₂}₂][CdCl ₄])_n (I). The molecular and crystal structures of compound I are determined from the X-ray diffraction data. Each of three ions is presented in the structure by two conformers. The irreversible decomposition of some dibutyldithiocarbamate groups is observed during the chemisorption of gold(III), which noticeably decreases the efficiency of gold binding with the sorbent studied and its sorption capacity. The study of the thermal properties of compound I shows that gold(III) is reduced to the metal during thermolysis. Pleiades Publishing, Ltd., 2010.

Full text of DOI:10.1134/S1070328410050064

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2010, Vol. 36, No. 5, pp. 353–358. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.V. Ivanov, V.I. Sergienko, A.V. Gerasimenko, O.V. Loseva, A.S. Zaeva, 2010, published in Koordinatsionnaya Khimiya, 2010, Vol. 36, No. 5, pp. 353–
358.
Formation of the Heteropolynuclear Complex
([NH2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4])n
during the Chemisorption of Gold(III) with Cadmium
DibutylDithiocarbamate: Structure and Thermal Properties
A. V. Ivanova ,*, V. I. Sergienkob, A. V. Gerasimenkob, O. V. Losevaa, and A. S. Zaevaa
a Institute of Geology and Nature Management, Far East Division, Russian Academy of Sciences, Blagoveshchensk, 675000 Russia
b Institute of Chemistry, Far East Division, Russian Academy of Sciences,
pr. Stoletiya Vladivostoka 159, Vladivostok, 690022 Russia
*Eꢀmail: alexander.v.ivanov@chemist.com
Received September 24, 2009
Abstract—The chemisorption properties of cadmium dibutyldithiocarbamate with respect to [AuCl4]– in
2M HCl solutions are studied. The heterogeneous reaction of gold(III) binding affords the heteropolynuclear
compound ([NH2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4])n (
pound are determined from the Xꢀray diffraction data. Each of three ions is presented in the structure by
two conformers. The irreversible decomposition of some dibutyldithiocarbamate groups is observed during
the chemisorption of gold(III), which noticeably decreases the efficiency of gold binding with the sorbent
I). The molecular and crystal structures of comꢀ
I
studied and its sorption capacity. The study of the thermal properties of compound
reduced to the metal during thermolysis.
I shows that gold(III) is
DOI: 10.1134/S1070328410050064
We have earlier reported the chemisorption properties of
cadmium diisobutyldithiocarbamate, which binds gold(III)
with a high efficiency in a wide concentration interval [1]. It
was shown that the chemisorption was accompanied by the
formation of the heteropolynuclear complex
EXPERIMENTAL
Sodium dibutyldithiocarbamate was obtained by
the reaction of carbon disulfide (Merck) and dibutyꢀ
lamine (Aldrich) in an alkaline medium [2]. The startꢀ
ing binuclear complex II was synthesized according to
published data [3]. The both compounds were characꢀ
terized by MAS 13C NMR spectroscopy.
[Au{S2CN(isoꢀC4H9)2}2]2n[CdCl4]n, whose structure was
determined by Xꢀray diffraction analysis. The studies
of the thermal properties of the complex found that the
single final thermolysis product was reduced metallic
gold. Therefore, it was of interest to study the chemiꢀ
sorption properties of other dithiocarbamate comꢀ
plexes (including longꢀchain alkyl substituents) and
the fixation mode of gold(III).
For Na{S2CN(C4H9)2}
55.2 (=NCH2 ), 30.0, 21.0 (
14.5 ppm (2 : 1 : 1, CH3).
⋅
H2O: 208.3 ( S2CN=),
−
−
−
CH2
−
), 15.6, 14.9,
−
1
For [Cd2{S2CN(C4H9)2}4] (II): 203.9, 200.2 (15) (1 : 1,
−
S2CN=); 62.9, 60.0, 59.5 (1 : 2 : 1, =NCH2
31.1, 30.1 (1 : 1 : 1 : 1), 22.1, 21.4, 21.0 (1 : 2 : 1,
16.2, 14.5, 14.4, 14.1 ppm (1 : 1 : 1 : 1, CH3).
The synthesis of compound I was carried out via the
reaction
−
); 33.2, 32.8,
−
CH2 );
−
−
In the present work, we studied the interaction of binuꢀ
clear
cadmium
dibutyldithiocarbamate
(Dtc),
[
Cd2{S2CN(C4H9)2}4] (chemisorbent II), with AuCl3
3[Cd2{S2CN(C4H9)2}4] + 4H[AuCl4] + 4HCl
= 4[NH2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4]
+ 2CdCl2 + 4CS2.
solutions in strongly acidic media and determined its sorpꢀ
tion capacity. The heterogeneous reaction of gold(III)
binding was shown to proceed via the chemisorption
mechanism to form bis(N,Nꢀdibutyldithiocarbamatoꢀ
S,S')gold(III) dibutylammonium tetrachlorocadmate
A solution of AuCl3 (100 ml, in 2 M hydrochloric
acid) containing gold (25 mg) was poured to complex
II (100 mg), and the mixture was stirred for 2.5 h. The
obtained yellow precipitate was filtered off, washed
with water, and dried on the filter. The prismatic crysꢀ
([NH2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4])n (I), whose
structure was established by Xꢀray diffraction analysis. The
study of the thermal properties was based on the simultaꢀ
neous thermal analysis (STA) data.
1
13
14
Asymmetric C– N doublet, in Hz.
353

354
IVANOV et al.
Table 1. Crystallographic data and the experimental and refineꢀ
ment parameters for structure I
of absorbed gold(III) was determined by this differꢀ
ence. The gold content in solutions was determined on
an atomic absorption spectrometer of the 1 class
(Hitachi, model 180ꢀ50).
Parameter
Empirical formula
Value
C26H56N3S4Cl4CdAu
990.14
The Xꢀray diffraction analysis of a prismatic single
crystal of compound
SMART 1000 CCD diffractometer (Mo
I
was carried out on a BRUKER
radiation,
FW
K
α
Crystal system
Triclinic
λ
= 0.71073 Å, graphite monochromator) at 203(2) K.
Space group
The data were collected in the hemisphere range using
a standard procedure [4], the crystal–detector disꢀ
tance being 45 mm. An Xꢀray absorption correction
was applied by equivalent reflections. The structure
was solved by a direct method and refined by least
squares in the anisotropic approximation of nonꢀ
hydrogen atoms. Positions of hydrogen atoms
were calculated geometrically and included into the
refinement in the riding model. The data were colꢀ
lected and edited and the unit cell parameters were
refined using the SMART [4] and SAINT [5] proꢀ
grams. The calculations on structure determination
and refinement were performed using the
SHELXTL/PC programs [6].
P
1
a
, Å
, Å
, Å
16.217(2)
16.619(2)
16.798(2)
89.442(2)
87.491(2)
61.661(2)
3980.6(7)
4
b
c
α
,
deg
deg
deg
β,
γ,
V
Z
, Å3
ρcalcd, g/cm3
, mm–1
(000)
1.652
μ
4.714
F
1968
The coordinates of atoms, bond lengths, and angles
were deposited with the Cambridge Crystallographic
Data Centre (no. 747431; deposit@ccdc.cam.ac.uk or
http://www.ccdc.cam.ac.uk). The main crystalloꢀ
graphic data and the results of refinement for structure
Crystal shape (size, mm)
Prism
0.22 × 0.18)
(0.42
×
Data collection in θ range, deg
1.83–28.25
Intervals of reflection indices
–21
–22
–22
≤
≤
≤
h
k
l
≤
≤
≤
21
22
22
I
are given in Table 1. The bond lengths and bond
angles are listed in Table 2. The hydrogen bonding
geometry is presented in Table 3.
Measured reflections
37011
18862 (Rint = 0.0834)
The thermal properties of compound I were studied
by the STA method including the simultaneous detecꢀ
tion of thermogravimetry (TG) and differential scanꢀ
ning calorimetry (DSC) curves. The study was carried
out on an STA 449C Jupiter instrument (NETZSCH)
in capped corundum crucibles with a hole in the cap
providing a vapor pressure of 1 atm during the thermal
decomposition of the sample. The heating rate was
5°C/min to 1100°C under an argon atmosphere. The
weight of the samples ranged from 4.13 to 8.92 mg.
Independent reflections
Reflections with
I
> 2
σ
(
I
)
11306
715
Refinement parameters
GOOF
R factors for F2 > 2
1.070
σ
(
F2
)
R
1 = 0.0872, wR2 = 0.2404
1 = 0.1401, wR2 = 0.2705
–3.486/4.987
R factors for all reflections
R
Residual electron
density(min/max), e
Å–3
The accuracy of temperature measurements was
−
1 ×
10 2 mg.
0.7
°
С
, and that of the weight change was
tals of compound I for Xꢀray diffraction analysis were
obtained from an acetone–chloroform–toluene
(1 : 1 : 1) mixture.
RESULTS AND DISCUSSION
A comparative analysis of the data on the kinetics
of gold(III) binding by sorbent II shows that the sorpꢀ
tion of gold from 100ꢀml solutions with low concenꢀ
The sorption of gold(III) was carried out in the
static regime. Solutions of H[AuCl4] (100 or 10 ml)
containing 0.41, 3.7 or 8.6, 38.1 mg of gold(III),
respectively, were poured to 100ꢀmg portions of sorꢀ
bent II. The mixtures were magnetically stirred for 1–
90 min at room temperature. To determine the residꢀ
ual gold concentration, 0.1 ml was sampled from the
solution at certain time intervals. The degree of sorpꢀ
trations of gold trichloride (Tabl. 4,
slowly than from small volumes (10 ml) of more conꢀ
centrated solutions (Tabl. 4, ) (Table 4). In the case
, the state of saturation of sorbent II is achieved after
a, b) occurs more
c, d
d
90 min, because even after a day the percentage of gold
binding remains almost unchanged. The white color of
sorbent II changes to lemonꢀyellow with an increase
in the depth of gold(III) sorption, whereas the soluꢀ
tion decolorizes. The changes observed indicate a
tion (S, %) was calculated by the formula
S
= [(с о)/ 100,
–
с
с] ×
where
с and со are the initial and residual gold conꢀ change in the chemical composition of the sorbent
tents, respectively, in the solution. The concentration and a possible formation of new compounds in the
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
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FORMATION OF THE HETEROPOLYNUCLEAR COMPLEX
355
Table 2. Selected bond lengths (d), bond angles (ω), and torsion angles (ϕ) of complex I
Bond
Angle
Angle
d
, Å
Bond
d, Å
Au(1)–S(1)
Au(1)–S(2)
Au(1)–S(3)
Au(1)–S(4)
S(1)–C(1)
2.330(2)
2.342(3)
2.324(3)
2.334(3)
1.731(10)
1.731(10)
1.716(11)
1.740(10)
1.299(12)
1.47(1)
1.48(1)
1.310(11)
1.48(1)
1.47(1)
1.46(1)
Au(2)–S(5)
Au(2)–S(6)
Au(2)–S(7)
Au(2)–S(8)
S(5)–C(19)
S(6)–C(19)
S(7)–C(28)
S(8)–C(28)
N(3)–C(19)
N(3)–C(20)
N(3)–C(24)
N(4)–C(28)
N(4)–C(29)
N(4)–C(33)
N(6)–C(49)
N(6)–C(45)
Cd(2)–Cl(5)
Cd(2)–Cl(6)
Cd(2)–Cl(7)
Cd(2)–Cl(8)
2.322(3)
2.327(3)
2.334(3)
2.333(3)
1.742(11)
1.742(11)
1.717(11)
1.735(10)
1.30(1)
1.456(11)
1.465(11)
1.325(12)
1.46(1)
S(2)–C(1)
S(3)–C(10)
S(4)–C(10)
N(1)–C(1)
N(1)–C(2)
N(1)–C(6)
N(2)–C(10)
N(2)–C(11)
N(2)–C(15)
N(5)–C(37)
N(5)–C(41)
Cd(1)–Cl(1)
Cd(1)–Cl(2)
Cd(1)–Cl(3)
Cd(1)–Cl(4)
1.46(1)
1.492(12)
1.491(11)
2.438(3)
2.463(3)
2.463(3)
2.451(3)
1.44(1)
2.434(3)
2.477(3)
2.463(3)
2.441(3)
ω
,
deg
Angle
ω
, deg
S(1)Au(1)S(2)
S(1)Au(1)S(4)
S(2)Au(1)S(3)
S(3)Au(1)S(4)
C(1)S(1)Au(1)
C(1)S(2)Au(1)
C(10)S(3)Au(1)
C(10)S(4)Au(1)
S(1)C(1)S(2)
S(3)C(10)S(4)
C(1)N(1)C(2)
C(1)N(1)C(6)
C(10)N(2)C(11)
C(10)N(2)C(15)
C(37)N(5)C(41)
Cl(1)Cd(1)Cl(2)
Cl(1)Cd(1)Cl(3)
Cl(2)Cd(1)Cl(3)
Cl(2)Cd(1)Cl(4)
Cl(3)Cd(1)Cl(4)
75.26(9)
105.07(9)
104.41(10)
75.26(9)
86.9(3)
86.5(3)
87.4(3)
86.6(3)
111.0(5)
110.8(5)
121.3(9)
120.4(9)
120.6(9)
121.4(9)
114.6(10)
107.37(10)
112.54(10)
106.24(10)
111.17(10)
109.49(11)
S(5)Au(2)S(6)
S(5)Au(2)S(8)
S(6)Au(2)S(7)
S(7)Au(2)S(8)
75.51(10)
104.86(9)
104.21(11)
75.43(10)
87.4(3)
87.2(3)
86.6(3)
86.3(3)
109.6(5)
111.6(5)
121.6(8)
121.3(8)
120.3(9)
121.3(9)
114.5(8)
113.34(11)
109.08(11)
110.92(11)
105.40(12)
108.34(10)
C(19)S(5)Au(2)
C(19)S(6)Au(2)
C(28)S(7)Au(2)
C(28)S(8)Au(2)
S(5)C(19)S(6)
S(7)C(28)S(8)
C(19)N(3)C(20)
C(19)N(3)C(24)
C(28)N(4)C(33)
C(28)N(4)C(29)
C(45)N(6)C(49)
Cl(5)Cd(2)Cl(6)
Cl(5)Cd(2)Cl(7)
Cl(6)Cd(2)Cl(7)
Cl(6)Cd(2)Cl(8)
Cl(7)Cd(2)Cl(8)
ϕ,
deg
Angle
ϕ
, deg
Au(1)S(1)S(2)C(1)
S(1)Au(1)C(1)S(2)
S(1)C(1)N(1)C(6)
S(2)C(1)N(1)C(2)
S(3)C(10)N(2)C(15)
S(4)C(10)N(2)C(11)
–173.5(7)
–174.1(6)
–177.6(8)
–179.4(9)
179.0(8)
Au(2)S(5)S(6)C(19)
S(5)Au(2)C(19)S(6)
S(5)C(19)N(3)C(24)
S(6)C(19)N(3)C(20)
S(7)C(28)N(4)C(33)
S(8)C(28)N(4)C(29)
–174.7(8)
–175.1(7)
176.8(9)
176.9(9)
–177.7(9)
–178.8(9)
177.0(8)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
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356
IVANOV et al.
Table 3. Hydrogen bonding geometry in complex I*
tylammonium
[NH2(C4H9)2]+
and
gold(III)
[Au{S2CN(C4H9)2}2]+ and the complex anions
Distance, Å
[CdCl4]2 . In the gold(III) cations the Dtc ligands are
−
coordinated by the complexing agent through the
Angle
N–H···Cl, deg
Contact N–H···Cl
N–H H···Cl
N···Cl
S,S'ꢀbidentate mode. Complex I includes pairs of the
structurally nonequivalent cations [NH2(C4H9)2]+
(with the N(5) and N(6) atoms) and
[Au{S2CN(C4H9)2}2]+ (Au(1) and Au(2)) and anions
N(5)–H(5
N(5)–H(5
N(6)–H(6
A
)
···Cl(3) 0.91 2.30 3.160(12)
···Cl(7)a 0.91 2.42 3.329(10)
158
173
163
B
)
A)···Cl(6) 0.91 2.38 3.261(9)
−
[CdCl4]2 (Cd(1) and Cd(2)). The character of strucꢀ
N(6)–H(6
B
)
···Cl(2)b 0.91 2.31 3.190(10)
163
tural differences in pairs of the ions discussed makes it
possible to classify them as conformers. We earlier
observed conformational isomerism for the whole
series of dialkyldithiocarbamate complexes [7–12]. In
a
b
* Symmetry transformations: –x+ 1, –y + 2, –z+ 1; –x + 1, –y + 1,
–z + 1.
−
the isomeric anions [CdCl4]2 the metal atoms exist in
Table 4. Kinetics of gold(III) binding with sorbent II
the distorted tetrahedral environment of four chlorine
atoms (the sp3ꢀhybrid state of cadmium). The
ClCd(1)Cl and ClCd(2)Cl bond angles lie in the
ranges 106.24°−112.54
tively.
Concentraꢀ Degree of sorption (%) for contact duration, min
tion of Au3+,
°
and 105.40°−113.34 , respecꢀ
°
1
10
20
30
60
90
mg/ml*
0.0041 (
0.037 (
0.86 (
3.81 (
a
)
58.1
83.6
61.2
55.1
62.3 67.5 76.1 81.0 82.5
84.8 85.9 89.0 91.2 93.4
63.7 90.1 98.4 99.6 99.8
Structure I has a unique organization: the alternatꢀ
b)
ing dibutylammonium cations and [CdCl4]2 anions
−
form zigzag polymeric chains along the crystalloꢀ
c
)
graphic axis y due to hydrogen bonds (Fig. 2). The disꢀ
d
)
56.4 56.8 59.8 66.9 82.0
crete complex cations [Au{S2CN(C4H9)2}2]+ form
peculiar lattice frameworks with the polymeric catꢀ
ion–anion chains discussed inside. In each
[NH2(C4H9)2]+ cation, the both hydrogen atoms interꢀ
act with the chlorine atoms of two adjacent nonequivꢀ
3+
* A solution of H[AuCl ] with different Au concentrations was
4
added by portions of (a, b) 100 or (c, d) 10 ml to 100ꢀmg portions
of sorbent II.
−
alent anions [CdCl4]2 . In turn, in each anion two
sorption system discussed. To check this assumption,
sorbent II saturated with gold was dissolved in an aceꢀ
tone–chloroform–toluene (1 : 1 : 1) mixture. Light
yellow transparent crystals of heteropolynuclear comꢀ
plex I, whose molecular and crystal structures were
determined by the Xꢀray diffraction method, were
obtained from this solution at 45°C.
chlorine atoms are involved in two hydrogen bonds
with the hydrogen atoms of two adjacent nonequivaꢀ
lent dibutylammonium cations. In each dibutylamꢀ
monium cation, one of the hydrogen atoms particiꢀ
pates in the formation of a noticeably stronger hydroꢀ
gen bond than that involving the second hydrogen
atom (Table 3).
The
isomeric
molecular
cations
The unit cell of structure
units (Fig. 1) containing the complex cations of dibuꢀ
I includes four formula
[Au{S2CN(C4H9)2}2]+ are noncentrosymmetric and
include two structurally nonequivalent Dtc ligand
each. The Au–S bond length is in a relatively narrow
interval: 2.322–2.342 Å. However, in the Au(2) cation
the ligands are almost isobidentate, whereas in the
Au(1) cation they demonstrate the reliably isobidenꢀ
tate coordination mode. The S,S'ꢀbidentate coordinaꢀ
tion of the Dtc ligands in the cations discussed results
in the formation of two fourꢀmembered metallocycles
z
y
0
Au(2)
Cd(1)
N(5)
[
AuS2C] with the common gold atom. The small sizes
of the cycles discussed are illustrated by the interꢀ
atomic distances Au⋅⋅⋅C 2.815–2.839 and ⋅⋅⋅S 2.844–
S
2.855 Å, which are substantially less than the sum of
the van der Waals radii of the corresponding pairs of
atoms: 3.36 and 3.60 Å [13–15]. The mutual arrangeꢀ
ment of atoms in the [AuS2C] metallocycle somewhat
deviates to a tetrahedron from the planar arrangement.
This is favored by the values of the AuSSC and SAuCS
Au(1)
N(6)
Cd(2)
x
torsion angles deviating from 180 (Table 2). The
°
geometry of the [AuS4] chromophores is close to
square, which is due to the lowꢀspin dsp2ꢀhybrid state
of gold(III).
Fig. 1. Packing of structural units in crystal I.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
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FORMATION OF THE HETEROPOLYNUCLEAR COMPLEX
357
(а)
b
Cl(4)
b
Cl(2)
Cl(6)
Cl(8)
H(6B)
H(6A)
b
H(5B)
b
b
Cd(1)
b
N(5)
H(5
Cd(2)
Cl(5)
A)
N(6)
c
b
Cl(7)
Cl(7)
Cl(1)
b
Cl(3)
(b)
(c)
C(36)
C(14)
C(12)
C(23)
C(35)
C(22)
C(8)
C(6)
C(13)
S(8)
S(7)
S(5)
C(9)
C(34)
C(20)
N(3)
C(33)
C(28)
N(4)
C(21)
C(25)
S(2)
Au(2)
S(3)
S(4)
C(7)
C(11)
Au(1)
C(19)
C(10)
N(1)
C(1)
C(24)
N(2)
C(15)
C(29)
C(2)
C(30)
C(3)
C(4)
S(1)
S(6)
C(31)
C(32)
C(26)
C(16)
C(17)
C(5)
C(18)
C(27)
+
2
−
Fig. 2. (a) Structure of the polymeric chain including the alternating ions [NH (C H ) ] and [CdCl ] ; (b, c) structure of the
2
4
9 2
4
+
isomeric cations [Au{S CN(C H ) } ] (ellipsoids of 50% probability).
2
4 9 2 2
In the Dtc ligands the SCNC torsion angles slightly sponds to the third stage. The inflections in the TG
differ from 180 or (Table 2), indicating the coplaꢀ curve in the lowꢀtemperature region (which are disꢀ
°
0
°
nar arrangement of atoms in the C2NC(S)S groups. tinctly seen in the differential TG curve) reflect a comꢀ
This fact along with the greater strength of the plicated character of thermolysis at the first stage with
N⎯C(S)S bonds (1.299–1.325 Å) compared to the a total weight loss of 61.9%. This value corresponds to
N–CH2 bonds (1.456–1.478 Å) indicate a substantial the thermal destruction of the dibutylammonium catꢀ
contribution of the double bonding to the formally ion, the dithiocarbamate part of the complex, and the
−
ordinary bond and admixing of sp2ꢀ to the sp3ꢀhybrid [CdCl4]2 anion with the reduction of metallic gold
state of the nitrogen and carbon atoms.
Since the dibutylammonium cations are in the
composition of compound I, the sorption capacity of
cadmium dibutyldithiocarbamate (compared to the
diisobutyldithiocarbamate complex [1]) is substanꢀ
tially lower. The established composition of comꢀ
and cadmium chloride liberation (the theoretical
weight loss is 61.60%). At the second stage the weight
loss is 16.8%, which is due to the almost complete subꢀ
limation of CdCl2 (the theoretical weight loss is
18.51%). At this stage the weight of the residue
(21.3%) exceeds the theoretical value for reduced gold
(19.89%) by approximately the weight of residual
CdCl2 (1.7%). Indeed, near the boiling point of CdCl2
(bp = 964°C) the TG curve detects the third stage of
weight loss being, however, 8.4%. (In the DSC curve,
the endotherm of weight loss transformed into the
endotherm of gold melting corresponds to this proꢀ
cess.) The observed discrepancy can be due to the fact
that the vaporization of residual CdCl2 near the meltꢀ
ing point of gold corresponds to the evaporation of
finely dispersed particles of the latter. After the cruciꢀ
ble was opened and the main portion of CdCl2 was
removed, sponge gold was observed. After the melting
point was passed, microscopic gold balls from 0.002 to
0.07 mm in diameter without slag traces were observed
(Fig. 3b).
pound
I corresponds to a sorption capacity of 252.0
mg of gold per 1 g of sorbent II and, correspondingly,
the binding of 1.33 Au3+ cations of each binuclear
molecule of the sorbent. The reason for the decrease in
the sorption capacity becomes clear as a result of conꢀ
sideration of the heterogeneous reaction between sorꢀ
bent II and a solution of gold(III) chloride in 2M HCl
(see Experimental): when gold(III) is bound with sorꢀ
bent II from strongly acidic media, a part of the startꢀ
ing dibutyldithiocarbamate ligands is the source of
dibutylammonium cations.
The STA method with the simultaneous detection
of TG and DSC curves was used to establish the optiꢀ
mum conditions of isolation of sorbed gold. The TG
curve detects the multistage process of weight loss
(Fig. 3a). The temperature interval 115–325
°
С
correꢀ
Thus, the chemisorption properties of cadmium dibuꢀ
sponds to the first stage, the second stage is an interval tyldithiocarbamate were studied for gold(III). The heteroꢀ
of 325–750 , and the interval 920–1085 correꢀ geneous reaction of gold(III) binding is accompanied by
°
С
°
С
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
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2010

358
IVANOV et al.
(а)
(b)
m
, %
100
90
80
70
60
50
40
30
20
TG
–61.9%
0.2 mm
–16.8%
–8.4%
Residual weight 12,9%
200
400
600
Temperature, °C
800
1000
Fig. 3. (a) TG curve of complex I and (b) the enlarged plan of the inner surface of the crucible with reduced gold balls after passing
the melting point.L
3. Ivanov, A.V., Konzelko, A.A., Gerasimenko, A.V.,
the formation of the heteropolynucler complex
([NH2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4])n whose
molecular and crystal structures were determined by Xꢀray
diffraction analysis. The presence of the dibutylammoꢀ
et al., Zh. Neorg. Khim. 2005, vol. 50, no. 11, p. 1827
,
[Russ. J. Inorg. Chem. (Engl. Transl.), vol. 50, no. 11,
p. 1710].
4. SMART. Madison (WI, USA): Bruker AXS, 1998.
5. SAINT. Madison (WI, USA): Bruker AXS, 2003.
6. Sheldrick, G.M., Acta Crystallogr., Sect. A: Found.
Crystallogr., 2008, vol. 64, p. 112.
nium cation in the composition of complex I results in a
noticeable decrease in the efficiency of gold binding with
sorbent II and in its sorption capacity (compared to cadꢀ
mium diisobutyldithiocarbamate [1]). The studies of the
thermal properties of the complexes showed that gold(III)
is reduced to the metal during thermolysis.
7. Ivanov, A.V. and Antzutkin, O.N., Topics Curr. Chem.
2005, vol. 246, p. 271.
,
8. Ivanov, A.V., Gerasimenko, A.V., Konzelko, A.A.,
et al., Inorg. Chim. Acta, 2006, vol. 359, no. 12, p. 3855.
9. Ivanov, A.V., Kritikos, M., Antzutkin, O.N., and
ACKNOWLEDGMENTS
Forsling, W., Inorg. Chim. Acta, 2001, vol. 321,
This work was supported by the Russian Foundaꢀ
tion for Basic Research (project no. 08ꢀ03ꢀ00068a),
and the Presidium of the Far East Division of the Rusꢀ
sian Academy of Sciences (grant no. 09ꢀIIIꢀVꢀ04ꢀ102
on fundamental and applied investigations of young
scientists).
nos. 1⎯2, p. 63.
10. Ivanov, A.V., Mitrofanova, V.I., Kritikos, M., and Antꢀ
zutkin, O.N., Polyhedron, 1999, vol. 18, no. 15, p. 2069.
11. Ivanov, A.V., Pakusina, A.P., Ivanov, M.A., et al., Dokl.
Akad. Nauk, 2005, vol. 401, no. 5, p. 643 [Dokl. Phys.
Chem. (Engl. Transl.), vol. 401, no. 2, p. 44].
12. Ivanov, A.V., Zaeva, A.S., Gerasimenko, A.V., and
Forsing, V., Dokl. Akad. Nauk, 2005, vol. 404, no. 4,
p. 505 [Dokl. Phys. Chem. (Engl. Transl.), vol. 404,
no. 2, p. 205].
13. Pauling, L., The Nature of the Chemical Bond and the
Structure of Molecules and Crystals, London: Cornell
Univ., 1960.
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No. 5
2010