Mechanically activated solid-phase synthesis of copper(II), zinc(II), and cadmium(II) diethyldithiocarbamates

Article abstract of DOI:10.1134/S0036023607060083

The mechanically activated solid-phase reaction of copper, zinc, and cadmium chlorides with sodium diethyldithiocarbamate is studied. The course of the process and the extent of reaction are studied as affected by the parameters of the mechanical activati

Full text of DOI:10.1134/S0036023607060083

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2007, Vol. 52, No. 6, pp. 865–870. © Pleiades Publishing, Inc., 2007.
Original Russian Text © L.A. Petrova, V.D. Makhaev, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 6, pp. 933–938.
COORDINATION
COMPOUNDS
Mechanically Activated Solid-Phase Synthesis of Copper(II),
Zinc(II), and Cadmium(II) Diethyldithiocarbamates
L. A. Petrova and V. D. Makhaev
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
Chernogolovka, Moscow oblast, 142432 Russia
e-mail: vim@icp.ac.ru
Received May 20, 2006
Abstract—The mechanically activated solid-phase reaction of copper, zinc, and cadmium chlorides
with sodium diethyldithiocarbamate is studied. The course of the process and the extent of reaction are studied
as affected by the parameters of the mechanical activation, subsequent heat treatment of the activated mixtures,
and the nature of the reagents. Vacuum sublimation isolated zinc, copper, and cadmium diethyldithiocarbamates
from mechanically activated mixtures. The extent of reaction reaches 97–99%.
DOI: 10.1134/S0036023607060083
Volatile metal complexes of sulfur-containing sealed off, mounted on the vibrational mill, and
ligands attract the attention of researchers largely on vibrated for the set time. Then, the reactor was unsealed
account of their use for preparing metal sulfides, which and the reaction mixture was separated. The mechani-
are an important group of electronic-engineering mate- cally activated mixture was investigated by IR spectros-
rials [1–3].
The feasibility of using mechanochemical synthesis
copy, X-ray powder diffraction, and complex thermal
analysis (TG, DTA, TA, DTA, and visual polythermal
observation). Part of the reaction mixture was used for
the preparative isolation of the individual product and
chemical analysis. The parameters of the mechanical
treatment and physicochemical investigations are
found elsewhere [5–9].
for the synthesis of compounds with sulfur-containing
ligands is poorly studied [4]. In the course of our sys-
tematic investigations [5–9], we developed methods for
the solid-phase synthesis of number of several coordi-
nation compounds with mechanical activation and
without solvents; we also determined some regularities
for these reactions. Therefore, it was pertinent to study
the possibilities of mechanochemical methods as
applied to the synthesis of compounds of S-donor
ligands.
Metal diethyldithiocarbamates were isolated by
sublimation at 160–230°ë in vacuum (~2 Pa). They
were identified by chemical analysis and physicochem-
ical methods. The X-ray diffraction patterns and IR
spectra of copper, zinc, and cadmium diethyldithiocar-
bamates are described in the table. Chemical analysis
was carried out at the Chemical Analysis Laboratory,
Here, we consider the results of our investigation of
the solid-phase reaction of CuCl , ZnCl , and CdCl
2
2
2
with sodium diethyldithiocarbamate in mixtures the Functional Inorganic Materials Department, the
mechanically activated on a vibrational ball mill.
Institute of Chemical Physics.
Synthesis of copper(II) diethyldithiocarbamate
EXPERIMENTAL
Cu(S CNEt ) . A mixture of CuCl (0.2878 g,
2
2 2
2
2
.140 mmol) and NaS CNEt (0.7621 g, 4.4408 mmol)
Anhydrous sodium diethyldithiocarbamate was pre-
pared by the dehydration of a commercial sample in
vacuum under heating [10]. Copper(II), zinc, and cad-
mium chlorides were prepared as in work [10].
Reaction mixtures and samples for physicochemical
investigations were prepared, the reactor was charged
and discharged, and all other manipulations with air-
sensitive compounds were performed in a dry box
under an inert atmosphere.
Experiments were carried out as follows. Weighed
amounts of activating filling, as well as a metal chloride
and sodium diethyldithiocarbamate in a proportion of
about 1 : 2, were placed to the reactor. The reactor was
2 2
was mechanically treated for 60 min. The reaction mix-
ture changed its color from yellow-white to grayish-
brown. A 0.2123-g fraction of the treated reaction mix-
ture was sublimed at 180–190°ë to isolate the product.
The product was obtained as brown crystals of
Cu(S CNEt ) (0.1558 g). The yield was 98.0% based
on CuCl . T = 198°ë (198°ë [11]). X-ray powder dif-
fraction data for the product coincided with the litera-
ture [12].
2
2 2
2
m
For Cu(S CNEt ) anal. calcd., wt %: Cu, 17.64.
2
2 2
Found, wt %: Cu, 17.2.
8
65

8
66
PETROVA, MAKHAEV
Synthesis of zinc(II) diethyldithiocarbamate
X-ray powder diffraction data for the product coin-
Zn(S CNEt ) . A mixture of ZnCl (0.2934 g, cided with the literature [12].
2
2 2
2
2
.152 mmol) and NaS CNEt (0.7771 g, 4.528 mmol)
2 2
For Zn(S CNEt ) anal. calcd., wt %: Zn, 18.06.
2 2 2
was mechanically treated for 10 min. Then, a 0.2806-g
fraction of the reaction mixture was sublimed in
vacuum at 150–165°ë to isolate the product.
Zn(S CNEt ) (0.1988 g) was obtained as white crys-
Found, wt %: Zn, 17.9.
Synthesis of cadmium(II) diethyldithiocarbam-
ate Cd(S CNEt ) . A mixture of CdCl (0.3766 g,
2
2 2
2
2
2 2
2
.054 mmol) and NaS CNEt (0.6788 g, 3.955 mmol)
tals. The yield was 97.0% based on ZnCl . T = 178°C
2 2
2
m
was mechanically treated for 60 min. Then, a 0.1500-g
(177°C [11], 178–180°ë [13]).
fraction of the reaction mixture was sublimed at
1
80−230°ë to isolate the product. Cd(S CNEt )
2 2 2
‡
(0.1110 g) was obtained as white crystals. The yield
was 96.6% based on NaS CNEt , T = 248−250°ë
2
2
m
[
11]). IR spectroscopic data coincided with the related
literature [14].
For Cd(S CNEt ) anal. calcd, wt %: Cd, 27.5.
2
2 2
b
Found, wt %: Cd, 27.0.
RESULTS AND DISCUSSION
The mechanical treatment of solid CuCl and
2
NaS CNEt on a vibrational mill changes the color of
2
2
the reaction mixtures from yellow-white after 5 s to
grayish-brown after 10–60 min of activation.
The X-ray diffraction pattern and IR spectrum
c
(
Fig. 1) of the CuCl + 2NaS CNEt reaction mixture
2 2 2
after 1 min of activation correspond to those of a mix-
ture of the reagents. The reflections and absorption
bands associated with the products of the exchange
reaction do not appear. After mechanical treatment for
1
0 min or longer, the X-ray diffraction patterns and IR
spectra show the reaction products and only traces of
the reagents in the reaction mixtures. The IR spectra of
copper, zinc, and cadmium diethyldithiocarbamates in
the region studied only insignificantly differ from the
NaS CNEt spectrum (table). Differential thermal anal-
d
e
2
2
ysis (DTA) shows that after mechanical treatment for a
period of 20 s to 15 min, the endotherm associated with
melting of NaS CNEt (155–158°ë) disappears.
2
2
Instead, an exotherm appears in the range 60–170°ë;
this peak does not appear in the DTA curves for the
reagents or individual reaction products. The peak tem-
perature of this exotherm shifts with mechanical activa-
tion time from ~160°ë after 1 min to ~70°ë after
1
5 min. The integrated intensity of the exotherm
decreases sharply with increasing activation duration. It
disappears after 30 min of activation; the DTA curves
for the reaction products only show the endotherm due
to melting of the product of the exchange reaction
(Cu(DEDTC) ). We showed previously [8, 15] that the
2
new exotherm generated by mechanical treatment is
due to the reaction of mechanically activated compo-
nents and the formation of reaction products. The dis-
appearance of this exotherm signifies the completion of
the mechanochemical reaction. Thus, the employed
physicochemical methods show that the mecha-
nochemically activated reaction
9
00
800
700
600
500
400
ν, cm–
1
Fig. 1. IR spectra for (a) NaS CNEt , (e) Cu(S CNEt ) ,
2
2
2
2 2
and (b–d) reaction mixtures after heat treatment for
b) 1 min, (c) 15 min, and (d) 1 min followed by heating.
(
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 6 2007

MECHANICALLY ACTIVATED SOLID-PHASE SYNTHESIS OF COPPER(II)
867
–
1
–1
Absorption frequencies (ν, cm ) in the IR spectra in the region 400–1300 cm and X-ray powder diffraction data (d, Å (I , %))
rel
for anhydrous crystalline copper(II), zinc(II), and cadmium(II) diethyldithiocarbamates
Compound
ν, cm–1
d, Å (I , %)*
rel
Cu(S CNEt )
505 m, 578 m, 600 w, 608 w, 730 m, 785 m, 855 s, 9.02(28), 8.68(20), 7.47(30), 6.12(22), 4.84(25),
22 s, 1003 s, 1082 s, 1105 m, 1155 s, 1218 s 4.52 (100), 4.40(30), 4.34(28), 4.16(75), 3.68(52),
.44(21), 3.08(26), 2.62(20).
2
2 2
9
3
Cd(S CNEt )
433 s, 515 m, 565 s, 617 m, 730 s, 782 s, 845s, 860 sh, 8.80(65), 7.44(84), 6.3(22), 4.86(27), 4.66(63),
2
2 2
9
20 s, 995 s, 1080 s, 1100 w, 1150 s, 1210 s, 1280 s 4.31(58), 4.16(100), 3.80 (68), 3.34(27),3.05(19),
2
.84(33), 2.69(24), 2.37(22).
Zn(S CNEt )
433 m, 510 m, 570 s, 618 m, 730 sh, 850 s, 910 s,
8.80(51), 7.41(94), 7.22(45), 6.21(30), 6.11(38),
5.07(37), 4.95(35), 4.51(58), 4.66(63), 4.43(89),
2
2 2
1
002 s, 1080 s, 1108 m, 1157 s, 1218 s, 1280 s
4
3
.28(100), 3.78(69), 3.66(56), 3.52(35), 3.14(36),
.01(24), 2.84(37), 2.68(33).
NaS CNEt
435 m, 475 m, 525 m, 572 s, 615 w, 728 m, 778 m, 12.11(34), 5.64(100), 5.30(80), 5.24(60); 4.21(54),
2
2
8
1
45 s, 920 s, 995 s,1075 m, 1100 m, 1140 s, 1215 s, 3.96.(15), 3.45(32), 3.31(32), 3.11(17), 2.93(20),
270 s
2.86(33), 2.62(24), 2.39.(24), 2.22(30), 2.11(15) [12].
*
Irel, % > 20.
CuCl + 2NaS CNEt
Cu(S CNEt ) + NaCl
Intensive grinding of CuCl + 2NaS CNEt mixtures
2
2
2
2
2 2
2
2
2
with a pestle and mortar for 5 min also initiates the
is over in 30 min.
exchange reaction yielding Cu(S CNEt ) and NaCl as
2
2 2
the products. A strong exotherm appears on the
DTA curve for the activated mixture in the range of
The X-ray diffraction patterns and IR spectra of the
reaction mixtures activated for 15 s and longer and then
heated to ~150°ë show only the products of the
exchange reaction: Cu(S CNEt ) and NaCl. Thus,
~100−180°ë with the peak at ~160°ë associated with
the reaction, and the endotherm appears at 195–200°ë
due to the melting of the newly formed Cu(S CNEt ) .
2
2 2
2
2 2
even after a short mechanical treatment (homogeniza-
The endotherm at 155–158°ë associated with the melt-
tion) of the reagents, heating of CuCl + 2NaS CNEt
2
2
2
ing of the starting NaS CNEt , does not appear on the
2
2
mixtures induces the exchange reaction and provides a
high conversion level. This distinguishes the test system
from the previously studied system CuCl −2NaC H O ,
DTA curve of the reaction mixture.
2
5
7
2
Physicochemical methods show that the solid-phase
where high extents of reaction were reached only after reaction of sodium diethyldithiocarbamate with zinc
1
h or longer of mechanical treatment [8]. The extent of chloride occurs differently. Stirring the reagents
conversion to Cu(S CNEt ) , which is isolated by heat- together does not generate a new exotherm on the DTA
ing the reaction mixtures in vacuum, is practically inde- curves. Two endotherms appear: the endotherm with
pendent of the mechanical treatment time: starting with
2
2 2
Tpeak = 155–158°ë associated with NaS CNEt melting
2
2
5
9
s and finishing with 60 min of activation, the yield is and an insignificant endotherm with Tpeak = 178°ë asso-
0–98%.
ciated with the melting of the product Zn(S CNEt ) .
2
2 2
The appearance of the exotherm on the DTA curves
for mechanically treated mixtures implies that the reac- ical treatment only shows reflections from the starting
tion of the mechanically activated reagents can be ZnCl and NaS CNEt . After 120 min of activation,
X-ray powder diffraction after 1–60 min of mechan-
2
2
2
accomplished in a self-propagating mode. Indeed, the low-intensity reflections of one reaction product (NaCl)
heating of one end of a cylindrical block of the com- appear in X-ray diffraction patterns (Fig. 2).
pacted reaction mixture on the Boethius microheating
In the IR spectra signs of the exchange reaction
table to 140–150°C initiates the process: the reaction
front moves along the block, and the starting yellow-
white mass is gradually converted to the brown product,
from which copper diethyldithiocarbamate is separated
appear only starting with 90 min of mechanical treat-
–1
ment. A broad absorption band at 1075–1100 cm is
–1
resolved into a pair of bands (1080 and 1105 cm ), and
–1
by sublimation. The temperature of the reaction front, the absorption band at 1147 cm acquires a shoulder at
–1
limited to the melting temperature of the newly pro- 1157 cm . After 120 min of mechanical treatment, the
–1
–1
duced Cu(S CNEt ) , is ~190–200°ë.
absorption band at 998 cm shifts to 1002 cm .
2
2 2
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 6 2007

8
68
PETROVA, MAKHAEV
‡
b
≈
≈
c
I
≈
≈
d
e
1
2
6
10
30
50
70
90
θ, deg
2
Fig. 2. X-ray diffraction patterns for (a) NaS CNEt , (e) Zn(S CNEt ) , and (b–d) reaction mixtures after heat treatment
2
2
2
2 2
for (b) 60 min, (c) 120 min, and (d) 5 min followed by heating. Notation: 1—NaCl; 2—Zn(S CNEt ) .
2
2 2
Thermal analysis shows the following results. After methods show that the mechanochemical reaction of
–120 min of treatment, an exotherm appears in the sodium diethyldithiocarbamate with zinc chloride does
1
region 175–178°ë on the DTA curves along with the not go to completion even in 120 min.
endotherm at 80–150°ë, which is associated with the
However, heating to 180°ë of the reaction mixtures
melting of the final product (zinc diethyldithiocarbam-
mechanically treated for 1–120 min initiates the
ate). The integrated intensity of the newly appearing exchange reaction with product formation, as deter-
exotherm systematically increases during 1–60 min of mined by X-ray powder diffraction and IR spectros-
activation; after 120 min, it decreases to become about copy:
one-half its maximal value (Fig. 3b), matching the
appearance of NaCl reflections in the X-ray diffraction
patterns and the shifts of the absorption bands in the IR
ZnCl + 2NaS CNEt
Zn(S CNEt ) + 2NaCl.
2 2 2
2
2
2
The investigation of the extent of conversion of the
spectra of activated mixtures. Thus, physicochemical reagents to zinc diethyldithiocarbamate as a function of
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 6 2007

MECHANICALLY ACTIVATED SOLID-PHASE SYNTHESIS OF COPPER(II)
869
mechanical activation duration shows that even after a
Yield, %
I, rel. units
short mechanical treatment (30 s), zinc diethyldithio-
carbamate sublimes upon heating of the reactions mix-
tures in vacuum. The extent of conversion to zinc dieth-
yldithiocarbamate is 88.5%. Further mechanical treat-
ment for 5 to 120 min does not change the extent of
conversion, which remains at 95–99% (Fig. 3a). The
residue after sublimation is mainly NaCl as shown by
chemical analysis and X-ray powder diffraction.
100
‡
b
3
2
1
50
1
0
We should note that after 5 min of intensive grinding
with a pestle, zinc diethyldithiocarbamate is also pro-
duced by sublimation, but with far lower yields (up to
5
10 30
τ, min
60
90
120
4
6%).
Fig. 3. Parameters of the reaction between zinc chloride and
sodium diethyldithiocarbamate vs. mechanical treatment
duration: (a) the extent of conversion of ZnCl2 to
Thus, as determined by preparative investigations,
IR spectroscopy, X-ray powder diffraction, and thermal
analysis, the mechanical treatment of mixtures of solid
sodium diethyldithiocarbamate with zinc(II) chloride
in the tested time intervals yields only insignificant
amounts of final products, unlike the reaction with cop-
Zn(S CNEt ) isolated by sublimation and (b) the inte-
2
2 2
grated intensity of the DTA exotherm in the region
0−150°C.
8
per(II) chloride. In order for the reaction to go to the ated with the reaction in response to increasing
end, mechanically activated mixtures should be heated. mechanical treatment duration, imply that with the
However, as in the reaction with copper(II) chloride, treatment duration used (60 min), the mechanochemi-
even short mechanical treatment (homogenization) of cal reaction mainly yields partial substitution products:
the reaction mixture is sufficient for heating of ZnCl +
2
2
NaS CNEt mixtures to initiate the exchange reaction
2 2
CdCl + 2NaS NEt
2 2 2
with high extents of conversion.
CdCl (S CNEt )2 – x+ (2 – x)NaCl.
x
2
2
We also studied the solid-phase reaction in the
CdCl –2NaS CNEt system during mechanical activa-
2
2
2
Thermal action is required to brought the reaction to
the end, as with zinc chloride. After heating the reaction
mixtures activated for 3 min and longer, X-ray diffrac-
tion patterns show the halo associated with an amor-
phous phase and the reflections of NaCl and
Cd(S CNEt ) produced by the exchange reaction.
tion. X-ray powder diffraction revealed that even after
–6 min of mechanical activation, the NaS CNEt
3
2
2
reflections disappear from the X-ray diffraction pat-
terns; a halo and broad CdCl reflections only remain.
2
After 10 min of heat treatment, broad and slightly
shifted NaCl reflections appear. After 20 min of treat-
2
2 2
The extent of conversion of the reagents to
ment, the CdCl reflections disappear, and the halo and
2
Cd(S CNEt ) isolated by sublimation is weakly
2
2 2
broad NaCl reflections only remain. Weak
affected by the mechanical treatment duration, as with
Cd(S CNEt ) reflections appear after 30 min of
2
2 2
ZnCl . For the reaction mixtures mechanically treated
2
mechanical treatment.
for 5–60 min, the product yields are 90–97%.
The IR spectra of reaction mixtures change in the
course of mechanical treatment, showing the formation
of full or partial substitution products, namely
We showed previously [8, 9] that in the solid-phase
mechanochemical synthesis of copper and zinc β-dike-
tonates, high extents of conversions are achieved only
after fairly long mechanical treatment. The characteris-
tic feature of the solid-phase synthesis of copper, zinc,
and cadmium diethyldithiocarbamates studied in this
Cd(S CNET ) or CdCk (S CNEt ) [14].
2
2 2
x
2
2 2 – x
DTA shows that the endotherm associated with
NaS CNEt melting at 155–158°C disappears as soon as
2
2
after 2 min of activation. An endotherm appears at work is the feasibility of providing an almost quantita-
2
40°C due to Cd(S CNEt ) melting, and a strong exo- tive conversion of the reagents to products through
2
2 2
therm appears in the range 60–130°C with its peak at heating the reaction mixture after several minutes of
about 95°C. With increasing treatment duration to mechanical treatment.
3
min, the intensity of this exotherm slightly increases;
then, it starts to decrease to become only 50% of its
maximal value after 60 min of activation. The evolution
of the IR spectra of activated mixtures, the disappear-
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