Application of acetone cyanohydrin in the synthesis of cyanide complexes of transition metals

Full text of DOI:10.1134/S1070363210020271

ISSN 1070-3632, Russian Journal of General Chemistry, 2010, Vol. 80, No. 2, pp. 357–358. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © Yu.S. Varshavskii, T.G. Cherkasova, 2010, published in Zhurnal Obshchei Khimii, 2010, Vol. 80, No. 2, pp. 332–333.
LETTERS
TO THE EDITOR
Application of Acetone Cyanohydrin in the Synthesis
of Cyanide Complexes of Transition Metals
Yu. S. Varshavskii and T. G. Cherkasova
St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia
e-mail: yurelv@gmail.com
Received September 10, 2009
DOI: 10.1134/S1070363210020271
In the work [1] we have described the triad
complexes [(CO)2ClRh(NC)RuPy4(CN)RhCl(CO)2],
[(Cod)ClRh(NC)RuPy4(CN)RhCl(Cod)], and [(Cod)·
ClRh(NC)RuPy4(CN)RhCl(CO)2] with ruthenium(II)
complex trans-[RuPy4(CN)2] (I) (Py is pyridine) as a
central unit [2]. The desire to avoid inconveniences
caused by the use of high-toxic KCN has resulted in
our attempt to apply acetone cyanohydrin, (CH3)2C·
(OH)(CN), as a source of cyanide ions in the synthesis
of complex I. Testing this reagent in the cyanide
process of gold oxidative dissolution has given
encouraging results in due time [3]. We have obtained
complex I with a satisfactory yield in experiments with
application of a water–alkaline solution of acetone
cyanohydrin instead of potassium cyanide.
The stretching frequencies of cyanide groups and
the chemical shifts of the cyanide carbon for all
synthesized complexes agree well with the published
data [6] and [7].
trans-[Ru(Py)4(CN)2]·2H2O was obtained accord-
ing to the procedure [2] with the replacement of KCN
by an alkaline solution of acetone cyanohydrin. A
solution of acetone cyanohydrin (0.8 ml) and KOH
(0.4 g) in water (25 ml) was added to a suspension of
trans-[Ru(Py)4(Cl)2] (1 g) in pyridine (80 ml). The
reaction mixture was boiled for 15 min. The golden
solution was evaporated to dryness under reduced
pressure at room temperature. The reaction product
was purified by the chromatographic method [2]. Yield
0.71 g (76%). IR spectrum, ν, cm–1: (CN) 2056
(CDHCl3), 2062 (mull in mineal oil). 13С NMR
spectrum (CDCl3), δ, ppm: 168.3 (CN), 157.1, 134.8,
124.2 (Py). Found, %: C 52.35; H 4.37; N 16.47.
C22H24N6O2Ru. Calculated, %: C 52.27; H 4.79; N
16.62.
[RuPy4Cl2] + 2(CH3)2C(OH)(CN) + 2KOH
→ [RuPy4(CN)2] + 2(CH3)2CO + 2KCl + 2H2O.
We are inclined to assume that such modification of
the procedure of synthesizing cyanide complexes of
transition metals can appear sufficiently general. Our
results on the synthesis of tetracyanide complexes of
nickel subgroup metals support this assumption.
K2[Ni(CN)4]·0.3H2O. a. Acetone cyanohydrin
(0.8 ml) and a solution of KОН (0.45 g) in water
(2 ml) were added to a hot solution of NiSO4·7H2O
(1.0 g) in water (4 ml). A pale-blue precipitate of Ni
(CN)2 was formed. The precipitate was filtered off,
washed with water, and dried in air. IR spectrum, ν,
cm–1: (CN) 2164. Resulting Ni(CN)2 was added to an
aqueous solution (2 ml) containing acetone cyano-
hydrin (0.8 ml) and KОН (0.45 g). The reaction mix-
ture was heated with stirring to complete dissolution of
the precipitate. The formed orange solution was
evaporated on a water bath to appearance of orange-
yellow crystals. After cooling to a room temperature
the precipitate was filtered off, washed with alcohol
We adhered to procedures given in the manuals [4]
(nickel and palladium) and [5] (platinum), replacing
potassium and sodium cyanides by an alkaline acetone
cyanohydrin solution. Nickel hydroxide readily reacts
with acetone cyanohydrin aqueous solution under
heterogeneous conditions to form the cyanide Ni(CN)2
without adding alkaline reagents.
Ni(OH)2 + 2(CH3)2C(OH)(CN)
→ Ni(CN)2 + 2(CH3)2CO + 2H2O.
We can expect that other metal hydroxides are also
capable of such reactions.
357

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VARSHAVSKII, CHERKASOVA
and ether, and dried in vacuum. Yield 0.6 g (69%). IR
spectrum, ν, cm–1: (CN), 2126, 2120. 13С NMR
spectrum (D2O), δ, ppm: 135.8 (CN). Found, %: C
19.52; N 22.73. C4H0.6K2N4NiO0.3. Calculated, %: C
19.50; N 22.74.
solution was formed, which became colorless during
further heating. The solution was evaporated on a
water bath and cooled in a refrigerator. After 4 h
colorless needle-like crystals possessing a charac-
teristic pleochroism were filtered off, washed with a
small amount of ice water, and dried in a desiccator
above sulfuric acid. Yield 0.7 g (88%). IR spectrum, ν,
cm–1: (CN) 2136, 2124. 13С NMR spectrum (D2O), δ,
b. Water (3 ml) and acetone cyanohydrin (1.55 ml)
were added to a weighted sample of Ni(OH)2 (0.39 g).
The reaction mixture was stirred at 70°С over 1 h. The
color of the precipitate gradually changed from light
green to pale blue as a result of Ni(CN)2 formation. On
addition of 2 ml of KOH (0.47 g) aqueous solution, the
precipitate instantaneously dissolved to form an orange
solution. The solution was evaporated on a water bath
to the appearance of orange-yellow crystals. After
cooling to a room temperature the precipitate was
filtered off, washed with alcohol and ether, and dried
in vacuum. Yield 0.89 g (88%). In spectral charac-
teristics the reaction product coincides with the sample
obtained in experiment a.
1
ppm: 125 [CN, J(CPt) 1030 Hz]. Found, %: C 12.27;
N 13.98. C4H2K2N4OPt. Calculated, %: C 12.15; N
14.17.
The IR spectra of samples in mulls in mineral oil
suspensions were measured on a Specord-75IR spec-
trometer. The 13С NMR spectra were measured on a
DPX-300 spectrometer with working frequency of
75 MHz. Chemical shifts (δ scale) were measured in
relation to internal references [CDCl3, δ(13C) 77.0
ppm; (CH3)2CO, δ(13C) 30.9 ppm].
ACKNOWLEDGMENTS
K2[Pd(CN)4]·H2O. A weighted sample of PdCl2
(0.5 g) was dissolved in water (35 ml) acidified by
hydrochloric acid (2 drops) with heating (~60°С) and
stirring. Acetone cyanohydrin (0.5 ml) and a solution
of KOH (0.32 g) in water (10 ml) were added to the
hot solution. The solution became colorless. A yellow
precipitate of Pd(CN)2 was formed. The precipitate
was filtered off, washed with water, transferred into a
beaker, and a solution containing acetone cyanohydrin
(0.55 ml) and KОН (0.35 g) in water (15 ml) was
added. A dominating part of the precipitate was
dissolved upon heating and stirring the reaction
mixture. The solution was filtered and evaporated to a
minimum volume. On cooling a colorless crystalline
precipitate was formed, which was filtered off and
dried in a desiccator above sulfuric acid. Yield 0.65 g
(76%). IR spectrum, ν, cm–1: (CN), 2142, 2130. 13С
NMR spectrum (D2O), δ, ppm: 131.51 (CN). Found,
%: C 15.58; N 18.22. C4H2K2N4OPd. Calculated, %: C
15.66; N 18.27.
This work was financially supported by the Russian
Foundation for Basic Research (project no. 09-03-
90416-Ukr_f_a).
REFERENCES
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K2[Pt(CN)4]·H2O. A solution of KОН (0.56 g) and
acetone cyanohydrin (0.9 ml) in water (3 ml) was
added to a suspension of K2[PtCl4] (0.84 g) in water
(2 ml). On heating (70°С) a transparent orange
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010