Reaction of lanthanide(II) and lanthanide(III) phenylethynyl cuprates with acetyl chloride

Article abstract of DOI:10.1134/S1070363210090082

Praseodymium and ytterbium phenylethynyl cuprates [(PhC≡C) ₃Cu]₃Pr₂(THF)₆ and {[(PhC≡C)₃Cu]?Yb(THF)₂}₂ react with acetyl chloride in tetrahydrofuran with elimination of phenylethynylcopper and formation of alkoxides [PhC≡C-CCl(CH₃)O] _n Ln (n = 3, Ln = Pr; n = 2, Ln = Yb). Then praseodymium alkoxide forms ester [methyl (phenylethynyl)chloromethylethanoate] and praseodymium chloride, alkoxy derivative. Itterbium alkoxide is oxidized to unsymmetrical dialkoxyitterbium chloride PhC≡C-CH(CH₃)-O-Yb(Cl)-O-CCl(CH₃) C≡CPh?2THF.

Full text of DOI:10.1134/S1070363210090082

ISSN 1070-3632, Russian Journal of General Chemistry, 2010, Vol. 80, No. 9, pp. 1767–1770. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © S.F. Zhil’tsov, M.A. Dydykina, O.N. Druzhkova, 2010, published in Zhurnal Obshchei Khimii, 2010, Vol. 80, No. 9, pp. 1448–1451.
Reaction of Lanthanide(II) and Lanthanide(III)
Phenylethynyl Cuprates with Acetyl Chloride
S. F. Zhil’tsov, M. A. Dydykina, and O. N. Druzhkova
Nizhnii Novgorod State Pedagogical University, ul. Ul’yanova 1, Nizhnii Novgorod, 603950 Russia
e-mail: chemical@nnspu.ru
Received December 3, 2009
Abstract―Praseodymium and ytterbium phenylethynyl cuprates [(PhC≡C)3Cu]3Pr2(THF)6 and {[(PhC≡C)3Cu]·
Yb(THF)2}2 react with acetyl chloride in tetrahydrofuran with elimination of phenylethynylcopper and
formation of alkoxides [PhC≡C–CCl(CH3)O]nLn (n = 3, Ln = Pr; n = 2, Ln = Yb). Then praseodymium
alkoxide forms ester [methyl (phenylethynyl)chloromethylethanoate] and praseodymium chloride, alkoxy
derivative. Itterbium alkoxide is oxidized to unsymmetrical dialkoxyitterbium chloride PhC≡C–CH(CH3)–O–
Yb(Cl)–O–CCl(CH3)C≡CPh·2THF.
DOI: 10.1134/S1070363210090082
Earlier [1], we reported on the methods for the
preparation of cationic lanthanide complexes of new
type by an example of phenylethynyl cuprates. It was
of interest to compare their reactivity with the well-
studied lithium organocuprates, which found applica-
tion as highly selective alkylarylating and arylating
agents in organic and organometallic synthesis.
solution. As known [2], lithium organocuprates [R2Cu]Li
react with acyl halides to form ketones in high yields.
In contrast, lanthanide phenylethynyl cuprates show
special features in the reactions with acetyl chloride.
We found that compounds I and II react with AcCl at
room temperature in THF affording copper phenyl-
ethynyl. As is well known [3, 4], the latter reacts with
acyl halides only at heating. The lanthanide
phenylethynyl derivatives formed at decomposition of
the complexes I and II add at the carbonyl group of
acetyl chloride, like in the case of reactions with esters
[5]:
This work is devoted to the reaction of
praseodymium(III) and ytterbium(II) phenylethynyl
cuprates [(PhC≡C)3Cu]3Pr2(THF)6 (I) and {[(PhC≡C)3Cu]·
Yb(THF)2}2 (II) with acetyl chloride in a THF
Cl
C
CH3
C O)3Pr
O
THF
(PhC
(PhC C)3Pr + 3 CH3C
III
Cl
The resulting praseodymium alkoxy derivative
shows high activity toward the acid chloride, typical
for the compounds of this type [6]:
In the reaction of acetyl chloride with compound I
at the molar ratio 4:1 calculated on triphenylethynyl-
prazeodimium (III), ester IV and bis[methyl(phenyl-
Cl
C
CH3
C O)3Pr + CH3C
O
(PhC
Cl
Cl
Cl
CH3
OCOCH3 + (PhC
CH3
C O)2PrCl THF
THF
PhC
C
C
C
V
IV
1767

1768
ZHIL’TSOV et al.
Yields and data of elemental analysis of compounds IV–VIII
Found, %
Calculated, %
Comp. Yield,
mp, °С
Formula
no.
%
C
H
Cl
–
Ln
–
C
H
Cl
–
Ln
–
71–185
mol
–
65.24
5.81
C12H11ClO2
64.72
4.91
IV
80
205–207 (decomp.) 46.84
3.25
4.83
4.96
15.33
17.66
10.44
24.56
26.85
25.06
C24H24Cl3O2Pr
C18H24Cl3O3Pr
C28H33Cl2O4Yb
47.41
40.34
49.63
3.95
4.48
4.87
17.53 23.21
19.89 26.33
10.49 25.55
V
92.8
92.3
~200 (decomp.)
140 (decomp.)
40.80
50.07
VI
VIII
ethynyl)chloromethyloxy]prazeodimiumfuranate chloride
(V) were isolated from the reaction mixture with the
yields, respectively, 0.7 and 0.8 mol per 1 mol of III.
They were identified by elemental analysis (see the
table) and by infrared spectroscopy. Methyl
(phenylethynyl)chloromethylethanoate IV is a slightly
colored liquid. IR spectrum (mineral oil), ν, cm–1: 1734
s, 3458 w (C=O), 1238 s (C–O), 1030 s (C–O–C),
2204 m (C≡C). The absorption bands 3458, 1238 and
1030 cm–1 indicate the presence of the ester acetate
group. The formed ester IV together with THF can
form a complex of type V with organolantanide
compound [7]. Compound V is dark brown substance,
moderately soluble in THF and insoluble in hexane.
We failed to isolate it in crystalline state.
At the increased molar ratio of acetyl chloride to
compound III of 6:1 the yield of ester IV grows to
1.85 mol per 1 mol of III. At the same time from the
reaction mixture was separated methyl(phenylethynyl)-
chloromethyloxyprazeodimiumdifuranate dichloride
VI, a brown substance insoluble in hexane.
Cl
C
CH3
OCOCH3 + PhC
Cl
C
Cl
C
CH3
O)3Pr + 2 CH3C
CH3
O
O
THF
PhC
C
(PhC
C
C
PrCl2 2THF
Cl
VI
Compound VI was identified by elemental analysis
(see the table) and the products of its hydrolysis. At the
hydrolysis of 1 mol of complex VI in hexane or di-
metoxyetane about 0.7 mol of ketone VII was isolated.
Cl
C
CH3
C OPrCl2(THF)2 + H2O
PhC
PhC
C
C
O
CH3 + PrCl3(THF)x
VII
Methyl phenylethynyl ketone VII was identified by
elemental analysis and by infrared spectroscopy. IR
spectrum (mineral oil), ν, cm–1: 1738 s (C=O), 2204 m
(PhC≡C).
complex II with acetyl chloride in a molar ratio 1:4 is
also accompanied by elimination of phenylethynyl-
copper and addition of ytterbium phenylethynyl
fragment to the acyl halide carbonyl group with
subsequent oxidation of the adduct to [methyl(phe-
nylethynyl)methyloxy][methyl(phenylethynyl)chloro-
methyloxy]ytterbiumdifuranate chloride (VIII):
Hydrolysis of alkoxy derivative V in hexane also
led to the formation of ketone VII. Reaction of
CH3
C
H
CH3
C
Cl
Cl
O
CH3
C
Cl
O
CH3
C
THF
C6H5C
C6H5C
C
O
Yb
C
CC6H5
C
O
Yb
C
CC6H5
Cl 2THF
VIII
THFx
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 9 2010

REACTION OF LANTHANIDE(II) AND LANTHANIDE(III)
1769
One of the chlorine atoms from the inner sphere of
the substituent is passed to the outer sphere, obviously,
with the participation of THF. The parent complex II
is diamagnetic. The effective magnetic moment of the
reaction product VIII is 4.3 μB, which corresponds to
the state of ytterbium(III). The complex VIII was
isolated from the reaction mixture in 85–90% yield and
identified by elemental analysis (see the table) and the
hydrolysis products. We failed to get it in the
crystalline state. Hydrolysis of the complex VIII in
hexane in contrast to compounds V and VI proceeds
with the formation of not only the ketone VII, but also
of alcohol IX:
sodium mirror. The necessary amount of solvent was
collected by condensation in a vacuum.
Reaction of [(PhC≡C)3Cu]3Pr2(THF)6 (I) with
acetyl chloride. To a solution of 3.08 g of compound I
in 15 ml of THF was added 1.07 g of acetyl chloride
(molar ratio I : CH3CClO = 1:8). At mixing the
reagents the reaction mixture warmed spontaneously,
and yellow precipitate of copper phenylethynyl with
admixture of alkoxide V formed. For completeness of
the reaction the ampule with the mixture was kept at
room temperature for 5 days. The solid insoluble in
THF, weighing 1.1 g, after separation, washing with
THF, and drying was mineralized with nitric acid in
the presence of H2O2. The resulting concentrations of
the Cu2+ ions (0.32 g, yield 99%), Pr3+ and Cl¯ (in
molar ratio 1:3) were determined by titration. Weight
of praseodymium 0.05 g (10% of the initial compound I).
VIII + H2O
hexane
C6H5C
C
CH(OH)CH3
IX
C CH3 + Yb(OH)Cl2
THF and possible volatile components of the
reaction were recondensed from the mother liquor in a
vacuum into a trap cooled with liquid nitrogen. In the
distillate were not detected phenylacetylene or acetyl
chloride. To the oily residue in the reaction ampule
hexane was condensed for precipitation of alkoxide V,
the latter was isolated, washed with hexane, and dried
to constant weight (1.67 g, yield ~80%). Brown
substance, mp 205–207ºC (decomp.). IR spectrum
(mineral oil), ν, cm–1: 3050, 2900–3000 (s), 1677,
1598, 1489, 1251, 756, 697; coordinated THF 1029.
+ C6H5
C
O
VII
Methyl(phenylethynyl)carbinol (IX) and methyl
phenylethynyl ketone were identified using IR
spectroscopy by the characteristic absorption
frequency O–H (3435 cm–1, broad, intensive), C=O
(1738 cm–1, s) and PhC≡C (2204 cm–1, m). Phenyl-
acetylene was not detected in the products of
hydrolysis.
From the hexane extract obtained after removal of
the solvent was isolated 0.54 g (yield 71 mol %) of
methyl(phenylethynyl)chloromethylethanoate IV.
EXPERIMENTAL
A suspension prepared from 0.63 g (0.001 mol) of
alkoxide V, 4 ml of hexane and 1 ml of H2O, was
subjected to hydrolysis at 50ºC for 1 h. As a result,
0.49 g of dark brown substance was isolated containing
~30% of Pr, and hexane extract of ketone VII.
The IR spectra were taken on spectrophotometers
Perkin-Elmer-577 and SPECORD 75 IR. The samples
of the compounds instable in air were prepared in a
vacuum or in an argon atmosphere as suspensions in
mineral oil. The melting and decomposition tem-
peratures of the substances were determined in sealed
evacuated capillaries. The values of melting and
decomposition temperature are given without
correction. Magnetochemical measurements were
carried out by method [8].
Similarly the reaction of compound I (2.54 g) was
carried out with acetyl chloride (1.32 g) at a molar ratio
1:12, in 15 ml of THF. Yield of ester IV was 1.15 g
(1.85 mol per 1 mol of the organopraseodymium
compound III). From the reaction mixture methyl-
(phenylethynyl)chloromethyloxyprazeodimiumdifura-
nate dichloride VI was separated, yield 1.4 g (92.8%).
The IR spectrum (mineral oil), ν, cm–1: 2900–3000 s,
1634, 1546, 1261, 1080, 803, 700, 611; coordi-
nationally bound THF 1026.
The preparation, separation, and purification of the
compounds unstable in air were carried out in
evacuated sealed ampoules using the Schlenk
technique. Organic solvents were purified by known
methods [9]. THF and hexane were additionally
distilled from sodium–benzophenone solution, degassed
and placed into evacuated ampule with pre-prepared
A solution of 0.55 g of compound VI in 7 ml of
THF and 2 ml of water was warmed for 2 h at 50ºC.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 9 2010

1770
ZHIL’TSOV et al.
Then the volatile products from the reaction mixture
were recondenced into a trap cooled with liquid
nitrogen. To the oily residue hexane was condensed.
From the resulting mixture a brown precipitate (0.45 g)
was isolated with the composition close to Pr(OH)Cl2·
3THF. Found, %: C 33.54, H 4.32, Cl 14.82, Pr 32.15.
C12H25Cl2O4Pr. Calculated, %: C 32.36, H 5.62, Cl
15.95, Pr 31.69.
C12H25O4Yb. Calculated, %: C 30.19, H 5.24, Cl
14.88, Yb 36.27.
Volatile liquid substances from the tetrahydrofuran
filtrate were recondensed in a vacuum into a trap
cooled with liquid nitrogen. To the oily residue hexane
was condensed. The solution formed was slightly
turbid. By centrifugation, the solution was separated
from the solid, and hexane was recondensed from it. In
the ampule remained slightly colored oil consisting of
a mixture of ketone VII and alcohol IX, weight 0.27 g,
which corresponds to the yield of a mixture 1.8 mol
per 1 mol of initial VIII. Compounds VII and IX
differ little in quantitative composition, the average
formula of the mixture is C10H9O. Found, %: C 82.26,
H 6.64. C10H9O. Calculated, %: C 82, 76, N 6,21.
After removal of hexane, from the filtrate 0.1 g
(70%) of ketone VII was isolated. Found, %: C 82.62,
H 6.05. C10H8O. Calculated, %: C 83.33, H 5.56.
Reaction of {[(PhC≡C)3Cu]Yb(THF)2}2 (II) with
acetyl chloride. To a solution of 1.78 g of compound
II in 15 ml of THF was added 0.41 g of acetyl
chloride. The reaction mixture was kept at room
temperature for 5 days. The change in color of the
solution and precipitation of phenylethynylcopper
contaminated with alkoxide VIII were observed. The
precipitate was separated, washed with THF, and dried
in a vacuum, weight 0.59 g. Then it was subjected to
mineralization with subsequent determination of Cu2+,
Yb3+, and Cl¯ by titration method. The weight of
copper was 0.16 g (yield 96.1%), and ytterbium, 0.02 g,
3.8% of its weight in the starting compound II. Molar
ratio of Yb3+ and Cl¯ is ~1:2.
ACKNOWLEDGMENTS
This work was supported by the Federal Agency for
Education.
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