Polynuclear complexes of gold(III) of the composition ([Au(S 2CNR2)2][AuCl4]) n (R = C4H9, R2 = (CH2)5): Synthesis, supramolecular structures, and thermal behavior

Article abstract of DOI:10.1134/S1070328411050071

The interaction of binuclear cadmium dialkyldithiocarbamates [Cd ₂(S₂CNR₂)₄] with solutions of AuCl₃ in 2M HCl gives polynuclear gold(III) complexes ([Au(S ₂CNR₂)₂][AuCl₄]) _n, where R = C₄H₉ (I) and R₂ = (CH₂) ₅ (II). The structures of the synthesized compounds solved by X-ray diffraction analysis are char-acterized by a complicated organization at the supramolecular level. The structures are based on polymer chains (I) and layers (II) involving isomeric cations [Au(S₂CNR₂) ₂]⁺ and anions [AuCl₄]^-. The thermal behavior of the synthesized complexes is studied by simultaneous thermal analysis including thermogravimetry and differential scanning calorimetry. The final product of the thermal transformations of the studied complexes is shown to be reduced metallic gold.

Full text of DOI:10.1134/S1070328411050071

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 6, pp. 452–459. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.V. Ivanov, S.A. Zinkin, A.V. Gerasimenko, V.I. Sergienko, 2011, published in Koordinatsionnaya Khimiya, 2011, Vol. 37, No. 6, pp. 450–457.
Polynuclear Complexes of Gold(III) of the Composition
([Au(S2CNR2)2][AuCl4])n (R = C4H9, R2 = (CH2)5): Synthesis,
Supramolecular Structures, and Thermal Behavior
A. V. Ivanova, *, S. A. Zinkina, A. V. Gerasimenkob, and V. I. Sergienkob
a Institute of Geology and Nature Management, Amur Scientific Center, Far East Branch, Russian Academy of Sciences,
Blagoveshchensk, 675000 Russia
b Institute of Chemistry, Far East Branch, Russian Academy of Sciences,
pr. Stoletiya Vladivostoka 159, Vladivostok, 690022 Russia
* Eꢀmail: alexander.v.ivanov@chemist.com
Received September 8, 2010
Abstract—The interaction of binuclear cadmium dialkyldithiocarbamates [Cd2(S2CNR2)4] with solutions of
AuCl3 in 2M HCl gives polynuclear gold(III) complexes ([Au(S2CNR2)2][AuCl4])n, where R = C4H9 (I) and
R2 = (CH2)5 (II). The structures of the synthesized compounds solved by Xꢀray diffraction analysis are charꢀ
acterized by a complicated organization at the supramolecular level. The structures are based on polymer
chains (
) and layers (II) involving isomeric cations [Au(S2CNR2)2]+ and anions [AuCl4]–. The thermal
I
behavior of the synthesized complexes is studied by simultaneous thermal analysis including thermogravimꢀ
etry and differential scanning calorimetry. The final product of the thermal transformations of the studied
complexes is shown to be reduced metallic gold.
DOI: 10.1134/S1070328411050071
INTRODUCTION
EXPERIMENTAL
Sodium dibutyldithiocarbamate and cycloꢀpenꢀ
tamethylenedithiocarbamate were synthesized by the
reactions of carbon disulfide (Merck) with dibutyꢀ
lamine (Aldrich) and piperidine (BDH Chemicals) in
an alkaline medium [4]. The initial binuclear cadꢀ
mium dithiocarbamates [Cd2(S2CNR2)4] (R = C4H9
We have previously reported the ability of the
dithiocarbamate complexes to binding gold(III) from
solutions, resulting in the formation of the heteropolyꢀ
nuclear ionic gold–cadmium complexes [1–3]. The
study of the thermal properties of the synthesized
compounds made it possible to establish that the final
thermolysis product was reduced gold. In the comꢀ
plexes discussed, gold(III) is present only in the comꢀ
position of the complex cations, although its binding
from strongly acidic media provides the possibility to
form complexes containing gold in the composition of
the anions as well. Therefore, it was of interest to study
the conditions of synthesis, the structural organizaꢀ
tion, and the thermal behavior of the dithiocarbamate
complexes containing gold(III) in both the cations
and anions.
(
Ia) and R2 = (CH2)5 (IIa)) were obtained as described
earlier [5, 6]. The both complexes were characterized
by MAS 15N NMR relative to crystalline NH4Cl
(0 ppm):
[
Cd2{S2CN(C4H9)2}4]: (1 : 1) 148.1 (16), 133.1 (26) ppm;
Cd2{S2CN(CH2)5}4]: (1 : 1 : 1 : 1) 142.5 (20), 141.2
(21), 129.5 (30), 126.4 (29) ppm (the spinꢀspin couꢀ
[
111, 113
pling constants 3J15
–
Cd are given in parentheses
in Hz). In the crysNtalline state complex IIa simultaꢀ
neously exists in two isomeric molecular forms [6].
Syntheses of I and II. A solution (10 ml) of AuCl3 in
2M hydrochloric acid containing gold (89.8 mg) was
poured to binuclear complexes Ia and IIa (100 mg).
The mixtures were stirred for 1.5 h until the heterogeꢀ
neous reaction of binding gold(III) ceased completely
In the present work, we synthesized the gold(III)
complexes with the dialkylꢀsubstituted and cyclic
dithiocarbamate (Dtc) ligands of the general composiꢀ
tion [Au(S2CNR2)2][AuCl4] (R = C4H9 (I), R2 = (CH2)5
(II)). The structures of the obtained compounds solved
by Xꢀray diffraction analyses are characterized by a
complicated organization at the supramolecular level.
n
[Cd2(S2CNR2)4] + 4nAuCl3
= 2([Au(S2CNR2)2][AuCl4])n + 2
nCdCl2.
The structures are based on polymer chains (
layers (II) involving the cations [Au(S2CNR2)2]+ and
anions [AuCl4]–. The thermal behavior of complexes
I) and
The bright yellow precipitates formed were filtered
off, washed with water, and dried on a filter. Single
I
and II was studied in an argon atmosphere by simultaꢀ crystals of polymeric bis(N,Nꢀdibutyldithiocarbamꢀ
neous thermal analysis. atoꢀS,S')gold(III) tetrachloroaurate(III),
452

POLYNUCLEAR COMPLEXES OF GOLD(III)
453
([Au{S2CN(C4H9)2}2][AuCl4])n
pentamethylenedithiocarbamatoꢀS,S')gold(III) tetraꢀ lent in pairs (hereinafter, cations
chloroaurate(III), ([Au{S2CN(CH2)5}2][AuCl4])n II), atoms and cations with the Au(2) atoms). The
were obtained from acetone and used for diffractometꢀ anions [AuCl4]– in structure
(anions for the anions
ric experiments. According to the established compoꢀ with Au(3) and anions for those with Au(4)) also
sition of obtained polynuclear compounds and II manifest nonequivalence. The character of structural
(
I
), and bis(N,Nꢀcyclo
ꢀ
cations [Au(S2CNR2)2]+ are structurally nonequivaꢀ
with the Au(1)
A
(
B
I
C
D
I
,
each binuclear molecule of the cadmium complex differences between cations A and B and between
interacts with four cations Au3+, which is accompaꢀ anions C and D (Table 2) allows one to classify them
nied by the binding from solution of 755.9 or 909.9 mg as conformational isomers [1–3, 10].
of gold per 1 g of cadmium dialkyldithiocarbamate Ia
or IIa, respectively. Thus, in the region of high conꢀ
tents of gold(III), the reaction with the cadmium
dialkyldithiocarbamate complexes occurs in a subꢀ
stantially different manner than in the region of modꢀ
erate concentrations [1–3].
In each isomeric cation with the composition
[Au(S2CNR2)2]+ (which are centrosymmetric in strucꢀ
ture II and noncentrosymmetric in structure I), the
central atom coordinates two Dtc ligands in the S,S'ꢀ
bidentate mode to form two fourꢀmembered metalloꢀ
cycles [AuS2C] joined through the common gold
atom. The Au–S bond length is 2.313–2.354 Å. Small
sizes of the metallocycles are confirmed by unusually
short interatomic distances gold–carbon (2.804–
2.836 Å) and sulfur–sulfur (2.853–2.869 Å). The
atoms in the [AuS2C] groups deviate from the plane
showing a slight tetrahedral distortion. The latter is
confirmed by the values of the torsion angles AuSSC
Xꢀray diffraction analyses of prismatic single crysꢀ
tals of complexes
I and II were carried out on a
BRUKER SMART 1000 CCD diffractometer (Mo
K
α
radiation, = 0.71073 Å, graphite monochromator) at
λ
203(2) K. Data collection was performed in the hemiꢀ
sphere region using the standard procedure [7] at a
crystal–detector distance of 45 mm. An Xꢀray absorpꢀ
tion correction was applied by equivalent reflections.
and SAuCS deviating by 1.5
°
–4.6
°
from 180 L In the
°
noncentrosymmetric isomeric anions [AuCl4]–
,
Structures
I and II were determined by a direct
method and refined by the leastꢀsquares method in the
anisotropic approximation for nonꢀhydrogen atoms.
The hydrogen atoms, whose positions were calculated
geometrically, were included into refinement in the
riding model. The data were collected and processed
and the unit cell parameters were refined by the
SMART [7] and SAINT [8] program packages. The
calculations on the determination and refinement of
the structures were performed using the
SHELXTL/PC programs [9].
The main crystallographic data and the results of
structure refinement for compounds I and II are given
in Table 1. The bond lengths and bond angles are listed
in Table 2. The coordinates of atoms, the bond
lengths, and the bond angles were deposited with the
the gold atom is surrounded by four chlorine atoms
(Au–Cl 2.268–2.290 Å). The diagonal angles SAuS
and ClAuCl in the chromophores [AuS4] and [AuCl4
are close to 180 , which indicates (in the both cases)
]
°
their planar structure caused by the intraorbital lowꢀ
spin dsp2ꢀhybrid state of gold(III).
The N–C(S)S bonds in the Dtc ligand are noticeꢀ
ably stronger (1.291–1.326 Å) than N–CH2 (1.471–
1.496 Å), which reflects the contribution of partialꢀ
doubleꢀbond character to the formally single bond.
This conclusion is also confirmed by an almost planar
geometry of the C2NC(S)S groups: the torsion angles
SCNC deviate from 180
°
or
0
°
by 0.1
°
–6.7 . The sixꢀ
°
membered heterocyclic fragments –N(CH2)5 in strucꢀ
ture II have a chair conformation.
Cambridge
(nos. 787580 (
Crystallographic
Data
Centre
1
Owing to relatively weak secondary interactions
I) and 787581 (II); deposit@
Au⋅⋅⋅S and Au⋅⋅⋅Cl of the nonvalence type, the complex
ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
Thermal behavior of complexes I and II was studied
by simultaneous thermal analysis and differential
scanning calorimetry. The studies were carried out on
an STA 449C Jupiter thermoanalyzer (NETZSCH) in
corundum crucibles under a cap with a hole providing
a vapor pressure of 1 atm during the decomposition of
cations [Au(S2CNR2)2]+ and anions [AuCl4]– particiꢀ
pate in the construction of a complicated supramolecꢀ
ular structure of complexes
I and II. All discussed disꢀ
tances Au⋅⋅⋅ and Au⋅⋅⋅Cl are equal to or somewhat
S
exceed the sum of the van der Waals radii of gold and
sulfur (3.46 Å [13, 14]), gold and chlorine (3.41 Å [13,
14]). Nevertheless, these interactions play a determinꢀ
ing role in the structural selfꢀorganization of the comꢀ
plexes at the supramolecular level.
In structure I, isomeric cations A and B participate
in the formation of zigzagꢀlike polymer chains along
the samples. The heating rate was
5
°
C/min to 1100 С
°
under an argon atmosphere. The sample mass ranged
from 1.04 to 5.65 mg. The accuracy of temperature
measurements was 0.7
°
С, and that of the mass
change was
1
×
10–2 mg.
1
The concept of secondary bonds was first proposed in [11] for
RESULTS AND DISCUSSION
The unit cells of compounds and II include four
formula units [Au(S2CNR2)2][AuCl4] (R = C4H9 ( ),
R2 = (CH2)5 II)). In the both structures, the complex
the description of interactions characterized by the distances
longer than single covalent bonds but shorter than the van der
Waals distances (the role of these interactions in the supramoꢀ
lecular organization of substances is also described in detail in
[12]).
I
I
(
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 6
2011

454
IVANOV et al.
Table 1. Crystallographic data and the experimental and refinement parameters for structures I and II
Parameter Value
Empirical formula
FW
C18H36N2S4Cl4Au2
944.46
C12H20N2S4Cl4Au2
856.27
Crystal system
Space group
Triclinic
Monoclinic
P
1
P21/n
a
, Å
, Å
14.2599(16)
15.4715(18)
15.8513(18)
71.007(2)
73.213(2)
68.880(2)
3025.7(6)
4
11.6424(10)
15.1232(12)
13.3264(12)
90.000
b
c
, Å
, deg
, deg
, deg
α
β
111.508(2)
90.000
γ
V
,
Å3
2183.0(3)
4
Z
ρcalcd, g/cm3
, mm–1
(000)
2.073
2.605
μ
10.326
14.298
F
1792
1584
Crystal shape (size, mm)
Prism
Prism
(0.32
×
0.17
×
0.03)
(0.22
×
0.21 × 0.07)
Data collection in θ range, deg
1.74–28.30
1.99–30.69
Range of reflection indices
–14
–16
–20
≤
≤
≤
h
k
l
≤
≤
≤
18
20
21
–15
–21
–18
≤
h
k
l
≤ 15
≤ 11
≤
17
≤
≤
Measured reflections
20387
int = 0.0545)
15802
6264 (Rint = 0.0306)
Independent reflections
14595 (
R
Number of reflections with
Refinement variables
Goodnessꢀofꢀfit
I
> 2σ
(I
)
8632
565
4581
220
0.969
1.023
R factors for F2 > 2
σ
(
F2
)
R
1 = 0.0566, wR2 = 0.1192
1 = 0.1134, wR2 = 0.1474
R
1 = 0.0290, wR2 = 0.0570
R factors for all reflections
R
R1 =0.0536, wR2 = 0.0638
Extinction coefficient
Was not refined
Residual electron density (min/max),
e
Å–3
–2.156/3.461
–1.372/2.347
the crystallographic axis
Au(2)bAu(2)Au(1) angles are 169.96
respectively. The character of paired alteration of the
gold(III) cations in the chain ⋅⋅⋅ ⋅⋅⋅ ⋅⋅⋅ ⋅⋅⋅ ⋅⋅⋅ is
shown in Fig. 1. The planes of the [AuS4] chroꢀ
mophores are parallel along the chain length for all
cations A and B, and the noncentrosymmetric cations
themselves in the pairs A–A and B–B are antiparallel.
In the A–B pairs, the mutual orientation of the cation
is that the bisector planes (passing through the both
fourꢀmembered metallocycles in A and B) form an
z
: the Au(1)aAu(1)Au(2) and Au(2)b⋅⋅⋅S(5) 3.486 Å) are involved in the formation of
°
and 167.94 ,
°
secondary bonds between cations B. The atoms Au(1),
Au(2), S(1), and S(7) (Au(1)⋅⋅⋅S(7) 3.530 Å and
Au(2)⋅⋅⋅S(1) 3.628 Å) participate in the formation of
secondary bonds between cations A and B. The menꢀ
tioned nonsymmetric character of interactions
between the isomeric cations determines the differꢀ
ence in distances between the gold atoms:
(
A А В B )
n
Au(1)⎯
Au(1)a 3.974 Å, Au(2)–Au(2)b 4.143 Å, and
Au(1)–Au(2) 3.906 Å. Anions C alter at the right and
left from the polymer chains. The structural ordering
of anions C is due to the interaction with cations A
only: Au(3)⋅⋅⋅S(1) is 3.572 Å and Au(3)–Au(1) is
angle close to 90
Au(1)⋅⋅⋅S(4)a and Au(1)a⋅⋅⋅S(4) 3.725 Å) participate in
the formation of secondary bonds between cations A.
°
. The atoms Au(1) and S(4)
(
The atoms Au(2) and S(5) (Au(2)⋅⋅⋅S(5)b and 4.661 Å. Isolated anions D are also arranged at the
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 6
2011

POLYNUCLEAR COMPLEXES OF GOLD(III)
Table 2. Selected bond lengths and bond angles for complexes I and II*
455
Bond
d,
Å
Angle
ω
, deg
I
Cations A – Au(1) and B – Au(2)
Au(1)–S(1)
Au(1)–S(2)
Au(1)–S(3)
Au(1)–S(4)
Au(1)⋅⋅⋅S(7)
Au(1)⋅⋅⋅S(4)a
S(1)–C(1)
2.337(2)
S(1)Au(1)S(2)
S(1)Au(1)S(3)
S(1)Au(1)S(4)
S(2)Au(1)S(3)
S(2)Au(1)S(4)
S(3)Au(1)S(4)
Au(1)S(1)C(1)
Au(1)S(2)C(1)
Au(1)S(3)C(10)
Au(1)S(4)C(10)
S(1)C(1)S(2)
75.47(6)
102.40(7)
177.11(8)
177.23(7)
106.70(6)
75.37(6)
86.8(2)
2.344(2)
2.313(2)
2.354(2)
3.530(2)
3.725(2)
1.715(7)
1.745(7)
1.722(7)
1.724(7)
1.291(9)
1.303(9)
2.346(2)
2.330(2)
2.334(2)
2.340(2)
3.628(2)
3.486(2)
1.725(7)
1.725(7)
1.728(7)
1.732(7)
1.326(8)
1.312(8)
S(2)–C(1)
85.9(2)
S(3)–C(10)
S(4)–C(10)
N(1)–C(1)
N(2)–C(10)
Au(2)–S(5)
Au(2)–S(6)
Au(2)–S(7)
Au(2)–S(8)
Au(2)⋅⋅⋅S(1)
Au(2)⋅⋅⋅S(5)b
S(5)–C(19)
S(6)–C(19)
S(7)–C(28)
S(8)–C(28)
N(3)–C(19)
N(4)–C(28)
87.0(2)
85.7(2)
111.7(4)
111.8(4)
75.69(6)
178.71(6)
105.71(6)
103.09(7)
176.47(8)
75.48(6)
85.6(2)
S(3)C(10)S(4)
S(5)Au(2)S(6)
S(5)Au(2)S(7)
S(5)Au(2)S(8)
S(6)Au(2)S(7)
S(6)Au(2)S(8)
S(7)Au(2)S(8)
Au(2)S(5)C(19)
Au(2)S(6)C(19)
Au(2)S(7)C(28)
Au(2)S(8)C(28)
S(5)C(19)S(6)
S(7)C(28)S(8)
86.1(2)
86.6(2)
86.3(2)
112.5(4)
111.6(4)
Anions C – Au(3) and D – Au(4)
Au(3)–Cl(1)
Au(3)–Cl(2)
Au(3)–Cl(3)
Au(3)–Cl(4)
Au(3)⋅⋅⋅S(1)
Au(4)–Cl(5)
Au(4)–Cl(6)
Au(4)–Cl(7)
Au(4)–Cl(8)
2.274(3)
2.283(2)
2.276(2)
2.268(3)
3.722(2)
2.282(3)
2.275(2)
2.289(3)
2.272(2)
Cl(1)Au(3)Cl(2)
Cl(1)Au(3)Cl(3)
Cl(1)Au(3)Cl(4)
Cl(2)Au(3)Cl(3)
Cl(3)Au(3)S(1)
Cl(5)Au(4)Cl(6)
Cl(5)Au(4)Cl(7)
Cl(5)Au(4)Cl(8)
Cl(6)Au(4)Cl(8)
90.01(11)
89.99(9)
179.70(10)
178.72(8)
96.74(6)
90.20(9)
177.80(8)
90.03(10)
179.49(9)
II
Anions A – Au(1) and B – Au(2)
Au(1)–S(1)
Au(1)–S(2)
2.3356(10)
S(1)Au(1)S(2)
75.30(3)
180.0
S(1)Au(1)S(1)a
Au(1)S(1)C(1)
Au(1)S(2)C(1)
S(1)Au(1)S(2)a
S(2)Au(1)S(2)a
2.3400(8)
S(1)–C(1)
S(2)–C(1)
N(1)–C(1)
1.730(3)
1.740(4)
1.298(4)
87.13(13)
86.76(11)
104.70(3)
N(1)–C(2)
1.476(4)
180.0
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 6
2011

456
IVANOV et al.
Table 2. (Condt.)
Bond
d,
Å
Angle
ω
, deg
N(1)–C(6)
Au(2)–S(3)
Au(2)–S(4)
Au(2)⋅⋅⋅Cl(3)c
Au(2)⋅⋅⋅Cl(3)d
S(3)–C(7)
1.472(5)
2.3389(10)
2.3420(9)
3.5852(12)
3.5852(12)
1.738(4)
S(1)C(1)S(2)
110.8(2)
75.15(3)
86.82(13)
86.94(12)
110.9(2)
83.75(3)
101.87(3)
180.0
S(3)Au(2)S(4)
Au(2)S(3)C(7)
Au(2)S(4)C(7)
S(3)C(7)S(4)
S(3)Au(2)Cl(3)c
S(4)Au(2)Cl(3)d
S(3)Au(2)S(3)b
S(3)Au(2)S(4)b
S(4)Au(2)S(4)b
S(4)–C(7)
1.728(4)
N(2)–C(7)
N(2)–C(8)
N(2)–C(12)
1.306(5)
1.477(5)
104.85(3)
180.0
1.473(5)
Anion C – Au(3)
Au(3)–Cl(1)
Au(3)–Cl(2)
Au(3)–Cl(3)
Au(3)–Cl(4)
Au(3)⋅⋅⋅S(3)c
2.2802(12)
2.2901(10)
2.2885(11)
2.2822(10)
Cl(1)Au(3)Cl(2)
Cl(1)Au(3)Cl(3)
Cl(1)Au(3)Cl(4)
Cl(2)Au(3)Cl(4)
90.60(4)
179.63(5)
89.58(4)
178.63(4)
3.5971(10)
Cl(4)Au(3)S(3)c
89.62(3)
a
b
a
b
c
d
* Symmetry transformations: (I) –x + 1, –y + 1, –z; –x, –y, z + 1; (II) –x + 1, –y, –z; –x + 2, –y, –z + 1; –x + 1, –y, –z + 1; x + 1, y, z.
edges of the chains but substantially farther: Au(2)⋅⋅⋅Cl(3)c, Au(2)⋅⋅⋅Cl(3)d (3.585 Å) and
Au(4)
⎯
Au(2) is 5.376 Å.
Au(3)⋅⋅⋅S(3)c (3.597 Å). The Au(2)–Au(3)c and
Au(2)–Au(3)d distances are 4.416 Å, and the
Complex II exhibits quite different type of strucꢀ
tural organization, which is characteristic of the alterꢀ
ation of corrugated layers parallel to the plane (101)
formed by the cations [Au{S2CN(CH2)5}2]+ and anions
[AuCl4]– (Fig. 2). The alteration of nonequivalent catꢀ
ions A and B in the layers is combined with the change
Au(3)c Au(2)Au(3)d angle is 180°. Owing to the nonꢀ
⎯
valent interactions Cl(2)⋅⋅⋅Cl(4)f [15], the fragments
discussed are structured into a polymer network,
whose each cell is occupied by isolated cations A.
The thermal behavior of complexes
I and II was
in their mutual spatial orientation. Each of cations B studied by thermal gravimetry (TG) and differential
forms
trinuclear
structural
fragments scanning calorimetry to establish the optimal condiꢀ
{[Au{S2CN(CH2)5}2][AuCl4]2}– with two adjacent tions of recovery of bound gold. Let us consider in
anions [AuCl4]– due to the secondary interactions detail the TG curves, whose character for compounds
Cl(2)
Au(3)
Cl(1)
Cl(4)
Cl(3)
S(6)
S(3)
S(5)
b
a
S(1)
S(4)
Au(2)
Au(1)
S(4)
S(2)
S(5)
S(7)
S(8)
Fig. 1. Construction of the polymer chains in structure
I
(alkyl substituents in ligands Dtc are omitted).
No. 6
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
2011

POLYNUCLEAR COMPLEXES OF GOLD(III)
457
S(1)
Au(1)
S(2)
f
Cl(4)
Cl(1)
Au(3)
Cl(4)
Cl(2)
c
Cl(3)
S(3)
c
Au(2)
Fig. 2. Polymer network in crystal II parallel to the plane (101). The cells are occupied by isolated cations A:
+
[Au{S CN(CH ) } ] (in ligands Dtc the structural fragments –N(CH ) are omitted).
2
2 5 2
2 5
I
and II is rather similar, using complex II as an examꢀ proceeds simultaneously at the cation and anion. The
ple. Three regions can be distinguished in the TG
curve (Fig. 3a): the lowꢀtemperature (below 227°C)
region reflecting a smooth mass loss of ~2.3%, the
intermediate (227–287°C) steeply descending region
with a main mass loss of 46.1%, and the smooth highꢀ
temperature (287–378°C) region with a mass loss of
4.8%. The independent measurement of the melting
points of the complexes in glass capillaries showed that
thermolysis of the cationic part of the complexes gives
Au2S with the decomposition temperature 240 (a
°
С
blackꢀbrown mass is observed after this temperature
was achieved and the crucibles were opened) as the
expected intermediate product [16]. Probably, AuCl
(
Tdecomp = 289°C) is the direct precursor of reduced
gold in the anionic part [16]. The temperature of
decomposition of gold(I) sulfide falls onto the range
the samples blackened to ~200
they melted with decomposition: gas bubbles evolved.
°
С
and at 230–240 С
°
227–287
not detected in the TG curve as a particular step.
Indeed, if the crucile was opened at 287 after the
°
С and, hence, the decomposition of Au2S is
°
С
Gold(III) enter into the composition of both the
cationic and anionic parts of the synthesized comꢀ
plexes. Therefore, when gold(III) is reduced inside the
cations and anions, thermal transformations can proꢀ
ceed in a different manner and may be accompanied
by the formation of various intermediate products.
However, a mass loss of 46.1% in the region from 227
main step of mass loss was passed, numerous incluꢀ
sions of fine particles of metallic gold were observed in
the residual mass of the substance. The last mass loss
step (287–378
decomposition of AuCl formed. At 287
beginning of AuCl decomposition, the overall mass of
°
С
) can be attributed to the thermal
°
С, before the
to 287°C indicates that the thermolysis of the complex AuCl and gold reduced from the complex cation
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 6
2011

458
IVANOV et al.
TG, %
100
–2.3%
(a)
90
80
70
60
50
1 mm
(b)
–46.1%
1 mm
–4.8%
(c)
46.3%
200
400
600
800
1000 T, °C
Fig. 3. (a) TG curve of complex II, (b) the enlarged view of the crucible bottom when 680°C is achieved, and (c) the melting
points of gold.
should be 50.15% of the initial mass (the real mass of these complexes were studied by Xꢀray diffraction and
the residue at this point somewhat exceeds the calcuꢀ simultaneous thermal analyses. The complexes are
lated value: 51.5%). The theoretical mass loss at the characterized by substantially different types of the strucꢀ
stage of AuCl decomposition is 4.14% (the observed ture. Structure I is based on the polymer chains formed by
mass loss is 4.8%).
alternating pairs of the isomeric cations, whereas the strucꢀ
tural fragments of complex II are the trinuclear anions catꢀ
ions {[Au{S2CN(CH2)5}2][AuCl4]2}– (forming polymer
If the crucibles were opened at the achievement of
680 С when the crucible mass was stabilized, finest
°
networks) and isolated cations [Au{S2CN(CH2)5}2]+
.
irregular dull gold leaves with a loose surface were
observed on the bottom (Fig. 3b). When the mp was
passed (extrapolated mp = 1061.8 and 1063.1 С), gold
The study of the thermal behavior of complexes I and
II showed that reduced metallic gold was the final
°
thermolysis product.
balls and hollow spheres from 0.3 to 0.003 mm in
diameter were observed (Fig. 3c). In the case of comꢀ
plex II, the mass of the metallic residue (46.6%) someꢀ
what exceeds the theoretically calculated mass of
reduced gold (46.01%), most likely, due to the accomꢀ
panying evolution of carbon under the conditions of
inert atmosphere (grayꢀblack spots are observed on the
bottom of the crucible). On the contrary, a noticeable
underestimation of the mass of the residue (35.6%)
compared to the theoretical value (41.71%) is
ACKNOWLEDGMENTS
This work was supported by the Russian Foundaꢀ
tion for Basic Research, project no. 08ꢀ03ꢀ00068ꢀa.
REFERENCES
1. Ivanov, A.V., Loseva, O.V., Gerasimenko, A.V., and
Sergienko, V.I., Dokl. Akad. Nauk, 2009, vol. 426,
no. 3, p. 338 [Dokl. Phys. Chem. (Engl. Transl.),
vol. 426, no. 3, p. 92].
observed for complex I. The latter can be explained by
the presence of an admixture of the heteronuclear
gold–cadmium complex in the studied samples of
complex I [2], which is favored by small steps of mass
loss in the TG curves (~2.5–3.0%) corresponding to
the evaporation of CdCl2 (400–600°C) and CdS
2. Loseva, O.V., Ivanov, A.V., Gerasimenko, A.V., et al.,
Koord. Khim., 2010, vol. 36, no. 1, p. 3 [Russ. J. Coord.
Chem. (Engl. Transl.), vol. 36, no. 1, p. 1].
(
925–110
°
С).
3. Ivanov, A.V., Sergienko, V.I., Gerasimenko, A.V., et al.,
Koord. Khim., 2010, vol. 36, no. 5, p. 353 [Russ. J.
Coord. Chem. (Engl. Transl.), vol. 36, no. 5, p. 353].
Thus, the interaction of binuclear cadmium dithioꢀ
carbamates with concentrated solutions of AuCl3 in
2M HCl results in gold(III) binding and the formation
of the polynuclear complexes of the general composiꢀ
tion ([Au(S2CNR2)2][AuCl4])n, where R = C4H9 and
R2 = (CH2)5. The structures and thermal behavior of
4. Byr’ko, V.M., Ditiokarbamaty (Dithiocarbamates),
Moscow: Nauka, 1984.
5. Casas, J.S., Sánchez, A., Bravo, J., et al., Inorg. Chim.
Acta, 1989, vol. 158, no. 1, p. 119.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 6
2011

POLYNUCLEAR COMPLEXES OF GOLD(III)
459
6. Ivanov, A.V., Gerasimenko, A.V., Konzelko, A.A., 12. Haiduc, I., Encyclopedia of Supramolecular Chemistry
,
et al., Inorg. Chim. Acta, 2006, vol. 359, no. 12, p. 3855.
7. SMART, Madison (WI, USA): Bruker AXS, 1998.
8. SAINT, Madison (WI, USA): Bruker AXS, 2003.
New York: Marcel Dekker, Inc, 2004, p. 1215.
13. Pauling, L., The Nature of the Chemical Bond and the
Structure of Molecules and Crystals, London: Cornell
Univ., 1960.
14. Bondi, A., J. Phys. Chem., 1964, vol. 68, no. 2, p. 441.
9. Sheldrick, G.M., Acta Crystallogr., Sect. A: Found.
Crystallogr., 2008, vol. 64, p. 112.
15. Grineva, O.V. and Zorkii, P.M., Kristallografiya, 2000,
vol. 45, no. 4, p. 692 [Crystallogr. Rep. (Engl. Transl.),
vol. 45, no. 4, p. 633].
16. Lidin, R.A., Andreeva, L.L., and Molochko, R.A.,
Spravochnik po neorganicheskoi khimii (Inorganic
Chemistry Handbook), Moscow: Khimiya, 1987.
10. Ivanov, A.V. and Antzutkin, O.N., Top. Curr. Chem.
2005, vol. 246, p. 271.
,
11. Alcock, N.W., Adv. Inorg. Chem. Radiochem., 1972,
vol. 15, no. 1, p. 1.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 6
2011