Synthesis and structure of bis[1-(1-adamantyl)-4,4,4-trifluorobutane-2,4- dionato]copper

Article abstract of DOI:10.1134/S1070363209010058

Previously unknown 1-(1-adamantyl)-4,4,4-trifluorobutane-2,4-dione and its copper complex, bis [1-(1-adamantyl)-4,4,4-trifluorobutane-2,4-dionato]copper, were synthesized. The ¹H NMR, IR, and ESR spectra and X-ray diffraction patterns of the sy

Full text of DOI:10.1134/S1070363209010058

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 1, pp. 31–36. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © V.K. Khamylov, T.S. Pochekutova, B.I. Petrov, M.V. Sizov, G.K. Fukin, Yu.A. Kurskii, A.V. Arapova, 2009, published in Zhurnal
Obshchei Khimii, 2009, Vol. 79, No. 1, pp. 33–38.
Synthesis and Structure of Bis[1-(1-adamantyl)-4,4,4-
trifluorobutane-2,4-dionato]copper
V. K. Khamylov, T. S. Pochekutova, B. I. Petrov, M. V. Sizov,
G. K. Fukin, Yu. A. Kurskii, and A. V. Arapova
Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
ul. Tropinina 49, Nizhny Novgorod, 603600 Russia
e-mail: khamylov@imoc.ras.ru, asteran@kis.ru
Received October 23, 2007
Abstract―Previously unknown 1-(1-adamantyl)- 4,4,4-trifluorobutane-2,4-dione and its copper complex, bis
1
[
1-(1-adamantyl)- 4,4,4-trifluorobutane-2,4-dionato]copper, were synthesized. The H NMR, IR, and ESR
spectra and X-ray diffraction patterns of the synthesized compounds were obtained. Volatilily and thermal
stability of the copper complex were studied by thermogravimetric analysis and differential scanning
calorimetry.
DOI: 10.1134/S1070363209010058
Copper(II) chelate complexes have a practical value
and used for preparing copper films and copper-
containing composites by means of metal organic
chemical vapor deposition (MOCVD) [1]. Despite the
large number of works dealing with synthesis and
properties of various copper β-diketonates, synthesis of
new volatile copper chelates capable of reproducibly
decomposing at low temperatures to form pure copper
films is an urgent task. The volatility of copper(II)
diketonates is enhanced by perfluorinated and bulky
substituents in the ligand. It is shown that the coordi-
native unsaturation of the Cu(II) cation characteristic
of fluorinated β-diketonates leads to formation of
dimeric structures or adducts with solvent molecules.
Due to that the composition and structure of fluorine-
containing copper chelates is much dependent on the
procedures of synthesis and isolation, as shown, for
fluoroacetone or 1,1,1-trifluoro-5,5-dimethylhexane-
2,4-dionate anion) containing a CF group and a bulky
3
tert-butyl substituent in the chelate ring [3–5]. We
considered it interesting to study the effect of the
volume of the hydrocarbon substituent in β-diketone
on the structure and properties of an unsymmetrical
fluorine-containing copper β-diketonate.
With this purpose we prepared previously unknown
1-(1-adamantyl)-4,4,4-trifluorobutane-2,4-dione (I) and
the corresponding copper β-diketonate, bis[1-(1-ada-
mantyl)-4,4,4-trifluorobutane-2,4-dionato]copper (II).
The present work deals with the synthesis of
compounds I and II and investigation of their structure
and properties.
Diketone I was prepared by means of Klaisen con-
densation in diethyl ether under the action of sodium
hydride [reaction (1)].
example, for the Cu(pta) complex (pta = pivaloyl tri-
2
O
3
1
4
C
2
C
Ad
Me
NaH
Ad
CH2
CF3
(1)
C
O
+ F C C
+ NaOC H .
2 5
3
OEt
O
O
I
Diketone I was isolated by converting it to copper
chelate II [reaction (2)] with the subsequent crys-
tallization from a dichloromethane–hexane mixture
and decomposition with 10% sulfuric acid. After iso-
lation from ethereal solution of diketone I was purified
by zone sublimation in a vacuum to give a white crys-
talline product readily soluble in polar organic sol-
–2
vents, mp 110°C, sublimation point 80°C (10 mm Hg).
31

3
2
KHAMYLOV et al.
F3C
H
C
_
Ad
C
O
C
O
Ad
CF3
CH2
C
O
C
O
+ (CH COO) Cu
Cu
+ CH COOH
(2)
3
2
3
O
C
O
C
_
C
H
CF3
Ad
II
The composition of diketone I is confirmed by IR
feature is the absence of the absorption band of the
hydroxy group at 3000–3300 cm related to the enolic
form of the β-diketone. This fact suggests that in the
1
–1
and H NMR data. The IR spectrum of compound I
contains a series of absorption bands characteristic of
the adamantyl substituent and corresponding to
published data [6]. The strong absorption band at
solid phase compound I exists in the ketone form.
1
The H NMR spectrum of diketone I in CDCl (Fig. 1)
3
–1
1
600–1592 cm related to C=O stretching vibrations
contained a group of signals of the adamantly protons
of fluorinated β-diketones [7]. The absorption bands at
3
at 1.670–2.083 ppm, as well as signals of the C
–
1
1
202 and 1160 cm can be attributed to C–F stretch-
methine proton at 5.95 ppm and hydroxyl proton at
ing vibrations of the CF group.
3
1
4.871 ppm. No signal which might be attributed to
3
–
1
the methylene protons at the C carbon atom of the
The absorption band at 975 cm is characteristic of
out-of-plane C–H vibrations of the chelate ring. It is
overlapped by the band related to C–H stretching
vibrations of the adamantyl substituent. A specific
diketone. From that it follows that compound I exists
in the CDCl solution in the enolic form, which is
3
characteristic of solutions of unsymmetrical
fluorinated β-diketones in polar solvents [8].
Copper chelate II was prepared by the reaction of
diketone I with aqueous Cu(II) acetate. Compound II
was crystallized from a dichloromethane–hexane
mixture and dried in a vacuum. Besides it was purified
–
2
by zone sublimation in a vacuum at 10 mm. The IR
spectra of both samples of complex II contain charac-
teristic absorption bands of the adamantyl substituent,
–
1
absorption bands at 1601 and 1553 cm of chelated
C=O and C=C bonds, and strong bands at 1150 and
2
–
1
1
106 cm related to C–F stretching vibra-tions. The
1
5 14 13 12 11 10 9 8 7 6 5 4 3 2 1 ppm
IR spectrum of the sample isolated by crystallization,
unlike that of the sample purified by zone sublimation,
contains a broad band of the hydroxy group in the
–
1
range 3100–3300 cm . The observation of this
absorption band points to the presence of coordinated
molecules of water in the final product. That means
that crystallization and drying in a vacuum fail to give
an anhydrous complex II. In the IR spectrum of the
sample purified by zone sublimation, no absorption in
–
1
the range 3100–3300 cm was observed. Hence,
sublima-tion removes coordinated or cocrystallized
water molecules.
×
16
1
1
1
5 14 13 12 11 10 9 8 7 6 5 4 3 2 1 ppm
The H NMR spectrum of compound II is
1
characterized by a significant broadening of the signal
Fig. 1. H NMR spectra of compounds (1) I and (2) II in
CDCl
3
3
.
of the proton at C of the chelate fragment and the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 1 2009

SYNTHESIS AND STRUCTURE OF BIS[1-(1-ADAMANTYL)-4,4,4-TRIFLUOROBUTANE-...
33
1
2A
1A
C
C
13A
C
14A
1
C
10A
C
9
A
C
8
A
7A
C
C
5
A
C
6
A
C
2A
1
AA
O
O
4
A
C
3
A
1
A
C
2
900 3000 3100 3200 3300 3400 3500
G]
Fig. 2. ESR spectrum of complex II.
Cu
[
1
A
C
A
1A
2AA
O
O
2
C
3
A
F
signals of adamantyl protons as compared to respective
signals of free diketone I (Fig. 1). Such changes are
characteristic of ESR-active compounds. The ESR
spectrum of complex II in toluene (Fig. 2) contains a
2
A
1A
F
F
signal typical of copper(II): g 2.128, a 76 G.
i
Fig. 3. Molecular structure of complex II. Thermal ellipsoids
are presented with 30% probabilities.
The structure of complex II was established by
means of X-ray diffraction (XRD). A general view of
this compound is presented in Fig. 3. The principal
bond lengths and angles are listed in Table 1,
crystallographic data and details of the XRD experi-
ment are presented in Table 2, and a fragment of the
crystal packing is shown in Fig. 4. The XRD study of
complex II showed that the independent part of the
cell contains two molecules of the complex, and the
copper cations are located in the inversion center. Each
The square-planar coordination of copper in com-
pound II means that the metal cation is coordinately
unsaturated. Analysis of the crystal packing showed
that both axial positions in the coordination sphere of
the copper cation are occupied by methylene groups of
the adamantyl fragments of neighboring molecules
...
(
Fig. 4). The Cu C distances are 3.281 Å, which is
2+
much smaller than the sum of the van der Waals radii
of these atoms (3.6 Å) [9].
Cu cation is coordinated to four oxygen atoms of the
chelate rings (square-planar coordination). The Cu–O
distances in II are 1.897(2)–1.981(1) Å, which is
typical of square-planar copper diketonates. For
Table 1. Principal interatomic distances (d) and bond angles
ω) in the complex II
example, the Cu–O distances in Cu(pta) are 1.899(5)–
2
(
1
.903(3) Å in the α phase [3] and 1.903(3)–1.926(3) Å
a
a
А
B
in the β phase [5]. The respective distances in Cu(F6-
Bond
d, Å
thd) [F -thd = 2,2-bis(trifluoromethyl)-6,6-dimethyl-
2
6
1
1
2
Cu –O
1.904(2)
1.906(1)
1.270(3)
1.267(2)
1.382(3)
1.409(3)
1.527(3)
1.522(3)
ω, deg
1.897(2)
1.918(1)
1.283(3)
1.266(3)
1.373(3)
1.413(3)
1.523(3)
1.517(3)
ω, deg
heptane-3,5-dionate anion] are 1.894(7) and 1.891(7) Å
5]. Note that in chelate II has the adamantyl and CF3
1
Cu –O
[
1
1
O –C
substituents trans to each other, while both phases of
2
4
O –C
complex Cu(pta) have CF cis to t-Bu. The O–C(CF )
2
3
3
1
3
4
2
5
[
1
1.270(3), 1.283(3) Å] and O–C(Ad) [1.267(2),
.266(3) Å] distances in compound II practically do
not reflect the difference in the electron-acceptor
electron-donor) properties of the Ad and CF groups.
C –C
3
C –C
1
C –C
4
(
C –C
3
Probably, packing effects in complex II compensate
differences in the electronic properties of substituents
in β-diketonate ligands.
Angle
1
1
2
O Cu O
92.92(6)
93.18(6)
a
A and B are independent molecules.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 1 2009

3
4
KHAMYLOV et al.
Table 2. Principal crystallographic characteristics of II, and
parameters of the experiment and refinement
To assess the relative volatility of complex II, we
performed thermogravimetric analysis (TGA) of com-
Parameters
II
pound II and known copper chelate Cu(pta) (Fig. 5).
2
Thermal properties of complex II were studied by
differential scanning calorimetry (DSC) (Fig. 6). The
DSC curve of compound II shows two endothermic
peaks. The first peak is at 240°C and relates to the
melting point of II. The melting enthalpy of the
complex is 43.6 kJ mol . The second peak is at 340°C
and corresponds to thermal decomposition of com-
pound II. Considering the TGA and DSC data we can
conclude that the compound in hand vaporizes without
decomposition in the temperature range 250–340°C.
Compound II under these conditions is less volatile
Formula
М
C
28
H
6 4
32CuF O
610.08
Syngony
Triclinic
Space group
P-1
Unit cell parameters
–
1
a, Å
10.9128(4)
11.4731(4)
11.7312(4)
97.434(1)
102.212(1)
108.783(1)
1327.78(8)
1.526
b, Å
c, Å
α, deg
β, deg
γ, deg
3
and more thermally stable than Cu(pta) Note also that
V, Ǻ
2.
–
3
the α and β phases of a crystalline complex Cu(pta)
2
ρcalc, g cm
.
..
...
has additional intermolecular Cu H and Cu F
Z
2
.
..
...
–
1
interactions. The inthermolecular Cu H and Cu F dis-
μ, mm
F(000)
0.898
tances in the α phase of Cu(pta) are 3.31 and 3.54 Å,
630
2
respectively [3], while in the β phase only Cu...H
θ range for the registered data, deg
1.82–26.00
intermolecular contacts are observed (3.39 and 3.44 Å)
–
13 ≤ h ≤ 13, –14 ≤ k ≤ 14,
Reflection index ranges
[
5]. In its turn, each copper cation in complex II has
–
14 ≤ l ≤ 14
...
Number of measured reflections
Independent reflections
11398
six intermolecular Cu H contacts (2.686–3.190 Å).
Each of them is significantly shorter than that in the Cu
5202 [Rint 0.0217]
2
(pta) complex. The fact that complex II is less volatile
GOOF (F )
1.025
2
than Cu(pta) is probably associated with a higher
energy of intermolecular Cu H contacts, as well as a
higher molecular weight of compound II. The presence
of shorter intermolecular contacts in chelate II also
favors a thicker packing and a higher thermal stability
R
1
0.0337,
2
R factors by I > 2σ(I)
...
wR
2
0.0797
0.0504,
R factors by all reflections
R
1
wR
2
0.0851
Residual electronic density,
0
.411/–0.279
–
3
max/min, e Å
of compound II as compared to Cu(pta) .
2
1
A
C
8BA
C
1B
Cu
8BD
C
1
C
Cu
Fig. 4. Fragment of the crystal packing of complex II.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 1 2009

SYNTHESIS AND STRUCTURE OF BIS[1-(1-ADAMANTYL)-4,4,4-TRIFLUOROBUTANE-...
35
%
↑ exo
0
1
00
–
–
1
2
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
–3
–
4
2
1
2
00
250
300
350
Т, °C
Fig. 6. DSC curve for complex II.
Hydrogen atoms in complex II were placed
geometrically and refined in the ride-on model.
The principal crystallographic characteristics and
parameters of the XRD experment and structure
refinement are listed in Table 1. The principal bond
angles and angles are presented in Table 2.
1
00
200
300
400 500 600
All calculations were carried out using the
SHELXTL program suit (version 6.10) [10].
Т, °C
2
Fig. 5. Thermograms of (1) complex II and (2) Cu(pta) .
Commercial sodium hydride in the form of a 40%
suspension in mineral oil (Aldrich) was used. Ethyl
trifluoroacetate was prepared by esterification of
EXPERIMENTAL
trifluoroacetic acid [11], bp 62°C, n 1.3070.
d
The IR spectra were measured on a DSM-1201 IR
spectrometer for suspensions in mineral oil in the
range 500–4000 cm .
1-Adamantylcarbonyl chloride and adamantyl
methyl ketone were prepared according to [12, 13].
The purity of the products was controlled by IR and
NMR spectroscopy.
–
1
1
The H NMR spectra were taken on a Bruker DPX-
2
00 spectrometer (200 MHz) in CDCl against internal
3
1-(1-Adamantyl)-4,4,4-trifluorobutane-2,4-dione
(I). A solution of 2.25 g of sodium hydride in 100 ml
of anhydrous diethyl ether was placed into a three-
necked flask equipped with a stirrer, a dropping funnel,
and a reflux condenser was purged with argon. Ethyl
trifluoroacetate, 5.6 g, and a solution of 6.5 g of
adamantyl methyl ketone in 20 ml of anhydrous ether
were added dropwise with stirring one after another.
The resulting obtained was stirred for 12 h and then
treated in portions with 10% sulfuric acid until a
weakly acidic reaction. The ethereal layer was
separated, and the aqueous layer was extracted with
ether. The combined ethereal solutions were treated with
a solution of 3.35 g of copper(II) acetate in 100 ml of
water and stirred for 1 h. The ethereal layer was
separated, the aqueous layer was extracted with ether,
and the combined extracts were dried over sodium
sulfate and evaporated to dryness. The resulting Cu(II)
chelate was crystallized from a dichloromethane–
hexane mixture, dissolved in ether, and decomposed
with 10% sulfuric acid. The etherial layer was dried
TMS.
Analysis for C and H was performed by elemental
microanalysis. Thermogravimetric studies were carried
out on a Perkin–Elmer PYRJS6-TGA instrument in the
temperature range 20–600°C under argon of special
purity grade, heating rate 5 deg min , sample 26 mg.
Thermal analysis was carried out on a Netzsch DSC
–
1
2
04 F1 Phoenix scanning calorimeter. Measurements
were carried out in the temperature range 20–400°C,
heating rate 5 deg min , argon flow rate 20 ml min ,
Al O crucible.
–
1
–1
2
3
The X-band ESR spectra were obtained on a Bruker
EMX spectrometer in toluene at room temperature.
X-ray diffraction studies were carried out on a
Smart APEX automatic diffractometer (graphite mono-
chromator, φ–ω scanning, MoK radiation) at 100 K.
The structure was solved by the direct method and
refined by the least-squares method on F in the
α
2
hkl
anisotropic approximation for all non-hydrogen atoms.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 1 2009

3
6
KHAMYLOV et al.
over sodium sulfate and evaporated to dryness in a
vacuum. Vacuum zone sublimation gave 6.1 g (60%)
of diketone I, mp 110°C, sublimation point 80°C
Russian Federation for Support of Leading Scientific
Schools (project no. NSh-1396.2008.3).
–
2
–1
REFERENCES
(
1
[
10 mm Hg). IR spectrum, cm : 2700, 2661[ν(CH)],
600, 1590 [diketone ν(C=O) and ν(C=C)], 1450
δ(HCH)], 1350 [δ(HCH), ω(CH )], 1284 [ν(C–C),
1
. Vetroprakhov, V.N. and Krupoder, S.A., Usp. Khim.,
000, vol. 69, no. 12, p. 1149.
2
2
ω(CH )], 1202, 1160 [ν(CF)], 1100, 975, 795 [δ(HCC),
2
2. Sievers, R.E. and Sadlowski, J.E., Science, 1978, vol. 201,
ν(CC)]. Found, %: C 61.20, H 6.29. C H F O .
1
4
17
3
2
no. 4352, p. 217.
Calculated, %: C 61.30, H 6.24.
3
4
5
6
. Polyanskaya, T.M., Rozhdestwenskaya, I.V., and Mar-
tynova, T.N., Zh. Strukt. Khim., 1993, vol. 34, no. 3,
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milov, S.A., and Igumenov, I.K., Izv. Sib. Otd. Akad.
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Phys., 1981, vol. 74, no. 11, p. 6522.
Bis[1-(1-adamantyl)-4,4,4-trifluorobutane-2,4-
dionato]copper (II). A solution of 4 g of diketone I in
5
0 ml of diethyl ether was treated with a solution of
2
.6 g of copper(II) acetate in 100 ml of water. The
reaction mixture was stirred for 1 h, the ethereal layer
was separated, the aqueous layer was extracted with
ether, and the combined ethereal extracts were washed
with water and dried over sodium sulfate. The ethereal
solution was evaporated, and the residue was twice
crystallized from a dichloromethane–hexane mixture
and twice sublimed in a vacuum to obtain 6.2 g (70%)
of compound II, mp 240°C, sublimation point 170°C
7. Yaqoub, M. and Koob, R.D., J. Inorg. Nucl. Chem.,
1971, vol. 33, p. 1944.
8. Sato, K., Ochi, H., and Arukava, K., Bull. Chem. Soc.
Jpn., 1969, vol. 42, no. 6, p. 1774.
–2
–1
(
10 mm Hg). IR spectrum, ν, cm : 2922, 2854, 2661
[
ν(CH)], 1601, 1533 [diketone ν(C=O) and ν(C=C)],
9. Batsanov, S.S., Zh. Neorg. Khim., 1991, vol. 36, no. 12,
p. 3015.
0. Sheldrick, G.M., SHELXTL. Version 6.12. Structure
Determination Software Suite, Madison, WI: Bruker,
1
1
1
4
454 [δ(HCH)], 1377, 1346, 1325 [δ(HCC), ω(CH )],
2
1
1
1
262, 1224, 1191 [δ(HCC))], 1150, 1106 [ν(CF)],
065–703 [δ(HCC), ν(CC)]. Found, %: C 54.95, H
.99. C H CuF O . Calculated, %: C 55.12, H 5.29.
2
000.
28
32
6
4
1. Weygand–Hilgetag, Organisch-chemische Experimen-
tierkunst, Hilgetag, G. and Martini, A., Eds., Leipzig:
Barth, 1964, 3rd ed.
ACKNOWLEDGMENTS
2. Hala, S. and Lianda, S., Coll. Czech. Chem. Commun.,
1
960, no. 25, p. 2692.
The work was financially supported by the Russian
Foundation for Basic Research (project no. 05-03-
2728-a) and the Program of the President of the
13. Fieser, L.F. and Nazer, M.Z., J. Med. Chem., 1967,
3
vol. 10, no. 4, p. 517.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 1 2009