Copper(I) π-complexes with 2-butyne-1,4-diol. Synthesis and crystal structure of (2-AmpH)[CuCl2(HOCH2C≡CCH 2OH)] (2-AmpH+ is 2-aminopyridinium cation)

Article abstract of DOI:10.1134/S1070328408080101

Crystals of the π-complex (2-AmpH)[CuCl₂(HOCH ₂C≡CCH₂OH)] (2-AmpH⁺ is the 2-aminopyridinium cation) were obtained by the reaction of 2-butyne-1,4-diol with CuCl in aqueous 2-aminopyridinium chloride solution and studied by X-ray diffraction: space group P, a= 7.172(4), b= 7.796(3), c = 11.60(9) A, α = 99.75(6)°, β = 96.53(7)°, γ = 101.03(3)°, Z = 2. The crystals consist of individual anions [CuCl₂(HOCH ₂C≡CCH₂OH)]^- and cations [2-AmpH] ⁺. The π-coordinated Cu(I) atoms of the complex anion have trigonal-planar surrounding of two chlorine atoms and C≡C bond of the 2-butyne-1,4-diol molecule. The alcohol groups form stable hydrogen bonds N-H...O (1.89 A) and O-H...Cl (2.20 A).

Full text of DOI:10.1134/S1070328408080101

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2008, Vol. 34, No. 8, pp. 619–623. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © Yu.I. Slyvka, B.M. Mykhalichko, M.G. Mys’kiv, V.N. Davydov, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 8, pp. 626–630.
Copper(I) p-Complexes with 2-Butyne-1,4-diol.
Synthesis and Crystal Structure
of (2-AmpH)[CuCl2(HOCH2C∫CCH2OH)] (2-AmpH+
is 2-Aminopyridinium Cation)
Yu. I. Slyvkaa, B. M. Mykhalichkob, M. G. Mys’kiva, and V. N. Davydova
a Franko National University, ul. Kirilla i Mefodiya 6, L’viv, UA-79005 Ukraine
b L’viv State University of Human Safety Management, L’viv, Ukraine
E-mail: myskiv@franko.lviv.ua
Received July 16, 2007
Abstract—Crystals of the π-complex (2-ÄmpH)[CuCl2(HOCH2C≡CCH2OH)] (2-ÄmpH+ is the 2-aminopy-
ridinium cation) were obtained by the reaction of 2-butyne-1,4-diol with CuCl in aqueous 2-aminopyridinium
chloride solution and studied by X-ray diffraction: space group P1, a = 7.172(4), b = 7.796(3), c = 11.60(9) Å,
α = 99.75(6)°, β = 96.53(7)°, γ = 101.03(3)°, Z = 2. The crystals consist of individual anions
[CuCl2(HOCH2C≡CCH2OH)]– and cations [2-ÄmpH]+. The π-coordinated Cu(I) atoms of the complex anion
have trigonal-planar surrounding of two chlorine atoms and ë≡ë bond of the 2-butyne-1,4-diol molecule. The
alcohol groups form stable hydrogen bonds N–H···O (1.89 Å) and O–H···Cl (2.20 Å).
DOI: 10.1134/S1070328408080101
In many processes of alkyne transformations cata-
lyzed by copper(I) salts [1, 2], the π-complexes of Cu(I)
with disubstituted alkynes are formed as intermediates
[3]. The systematic study of their structures is the nec-
essary step of elucidation of the mechanism of cupro-
catalytic processes.
EXPERIMENTAL
Synthesis. Crystals of the π-complex I were
obtained by interaction of Cu(I) chloride with
2-butyne-1,4-diol in aqueous 2-aminopyridinium chlo-
ride solution. The saturated aqueous solution of 2-ami-
nopyridinium (0.9 g, 0.01 mol) titrated with HCl to
pH ~3 was prepared and then, CuCl (1.0 g, 0.01 mol)
and HOCH2C≡CCH2OH (0.9 g, 0.01 mol) were added
at ~90°ë. On slow cooling to room temperature, color-
less crystals of complex I were formed.
The previous study of the π-complex formation of
Cu(I)
halides
with
2-butyne-1,4-diol,
HOCH2C≡CCH2OH (L), in aqueous CuCl and MCl
solutions (å+ is cation of the alkali metals, ammonium,
and organic amines) using the formation of the anionic
π-complexes K[CuBr2(L)] [4], K[CuCl2(L)] and
NH4[CuCl2(L)] [5], Rb[CuCl2(L)] (modifications A and
B) [6], Cs[CuCl2(L)] · H2O [7], and (ImH)[CuCl2(L)] (II)
(ImH+ is the imidazolinium cation) [8] as examples,
showed that the efficiency of π-bonding Cu(I)–(ë≡ë)
and the formation of the Cu(I) anionic π-complexes
with 2-butyne-1,4-diol is predetermined by capability
X-ray diffraction analysis of the crystals, prelimi-
narily studied by the photomethod, was performed on a
DARCh single-crystal automated diffractometer
(åÓäα radiation, θ/2θ scan mode). The crystal param-
eters, the summary of data collection and crystallo-
graphic characteristics of complex I are listed in
Table 1.
The structure of the complex was solved by the
of the outer-sphere å+ cation to realize the target cat- direct methods with the CSD program package [9];
ion–anion interaction.
After localization and refinement of all non-hydrogen
atoms by the least-squares method in isotropic approx-
imation, the absorption correction was applied with the
DIFABS program. The hydrogen atoms were located
geometrically. For non-hydrogen atoms, the final struc-
ture refinement was performed in anisotropic variant.
The positional parameters of the H atoms were not
refined, the temperature factor was refined as a group
parameter. The atomic coordinates and their thermal
parameters are given in Table 2.
It was of interest to study the structure-forming
function of 2-aminopyridinium chloride in the process
of the π-complex formation of CuCl with 2-butyne-1,4-
diol. With this aim in view, we obtained and studied by
X-ray diffraction the crystals of the anionic π-complex
(2-ÄmpH)[CuCl2(L)] (I) in the system (2-AmpH)Cl-
CuCl-L-H2O (2-AmpH+ is the cation of 2-aminopyri-
dinium (C5N2H+7 )).
619

620
SLYVKA et al.
Table 1. The crystallographic parameters and summary of data Table 2. The atomic coordinates and thermal parameters in
collection for single crystal of (C5NH5NH2)[CuCl2(C4H6O2)]
structure I*
Atom
x
y
z
Ueq, Å2
Parameter
Value
Cu
0.20478(6) 0.41330(5) 0.40879(4) 0.0415(2)
M
315.66
293
Cl(1) 0.2009(2) 0.52647(1) 0.24239(8) 0.0525(3)
Cl(2) 0.13808(2) 0.11633(1) 0.35554(9) 0.0525(3)
T, K
Space group
O(1)
O(2)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
H(1)
H(2)
H(3)
H(4)
H(5)
H(6)
H(7)
H(8)
H(9)
0.4241(5) 0.9224(4) 0.6404(3) 0.060(1)
0.3478(7) 0.4119(5) 0.7751(3) 0.086(2)
0.2277(5) 0.0625(4) 0.0874(3) 0.046(1)
0.2970(6) 0.3066(5) –0.0023(3) 0.058(1)
0.3216(6) 0.8054(5) 0.5359(4) 0.048(1)
0.2821(5) 0.6163(4) 0.5492(3) 0.039(1)
0.2593(5) 0.4779(5) 0.5863(3) 0.039(1)
0.2478(6) 0.3409(5) 0.6613(3) 0.047(1)
0.2699(5) 0.1297(5) –0.0088(3) 0.041(1)
0.2831(5) 0.0128(5) –0.1110(3) 0.044(1)
0.2528(6) –0.1646(5) –0.1123(4) 0.052(1)
0.2116(7) –0.2309(5) –0.0121(4) 0.059(2)
0.2001(6) –0.1168(5) 0.0864(4) 0.053(1)
P1
Unit cell parameters:
a, Å
7.172(4)
7.796(3)
11.60(9)
99.75(6)
96.53(7)
101.03(3)
620(6)
b, Å
c, Å
α, deg
β, deg
γ, deg
V, Å3
µ(MoKα), cm–1
ρ(exp), g/cm3
ρ(calcd.), g/cm3
Z
22.39
1.65(2)
1.67(2)
2
0.551
0.492
0.200
0.398
0.109
0.297
0.217
0.287
0.329
0.889
0.456
0.842
0.818
0.298
0.239
0.145
0.387
0.360
0.060
–0.248
–0.362
–0.162
0.660
0.768
0.517
0.470
0.670
0.623
0.162
0.073
–0.073
–0.183
–0.186
–0.013
0.159
Crystal size, mm
F(000)
0.2 × 0.3 × 0.4
313.0
2θmax, deg
57.00
Number of independent
reflections
2536
Number of independent
reflections with |F ≥ 4σ(F)|*
2027
H(10) 0.316
H(11) 0.260
H(12) 0.190
H(13) 0.170
Weighting scheme (w)
[σ(Fo)2 + 0.0037σ(Fo)2]–1
R
0.0425
0.0540
Rw
* For non-hydrogen atoms U = 1/3
U a*a*(aiaj), for H
ij i j
∑∑
eq
i
j
atoms, Uiso(total) = 0.102 Å2.
* With correction for Lorentz and polarization factor.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 8 2008

COPPER(I) π-COMPLEXES WITH 2-BUTYNE-1,4-DIOL
621
Cl
H
C
O
Cu
C
N
y
z
x
Fig. 1. The structure of π-complex I.
RESULTS AND DISCUSSION
bond π-coordinated at the metal center is elongated to
1.22(2) Å (Table 3) (in a free molecule L [10], the C≡C
bond length is 1.200(2) Å). Note that in structure II [8],
the C≡C bond is not almost elongated (1.208(7) Å),
while in cuprobromide compound with the alkali metal
The structure of π-complex I (Fig. 1) is similar to the
structure of previously studied complex II consisting of
individual
complex
anions
[CuCl2(HOCH2C≡CCH2OH)]– and the 2-aminopyri-
dinium cations located in a free space between the
anions. Despite the presence of three functional groups
(the C≡C bonds and two alcohol groups at the opposite
sides of a molecule) in 2-butyne-1,4-diol, the Cu(I)
atom in the complex anion is coordinated with a ligand
molecule particularly at the ë≡ë bond. In addition to
the ethynyl group, the metal atom is bonded also with
two Cl atoms thus completing its coordination number
to three (Fig. 2).
cations
in
the
outer
sphere
(ä[CuBr2(HOCH2C≡CCH2OH)] [1]), the C≡C bond is
significantly elongated to 1.24(1) Å.
In complex I, two “halves” of the 2-butyne-1,4-
diol molecules have almost identical conformation
about the midpoint of the C≡C bond; each fragment
≡ë–ë–é–ç has a synclinal configuration with respect
to the bonds C(1)–O(1) and C(4)–O(2) (the corre-
sponding torsion angles C(2)C(1)O(1)H(1) and
As a result of the π-bonding Cu–(C≡C) in complex I, C(3)C(4)O(2)H(2) being 60.1° and –61.7°). The above
the geometry of the HOCH2C≡CCH2OH molecule is conformation peculiarities of the 2-butyne-1,4-diol
slightly changed as compared to a free molecule of molecule are explained by involvement of the H atoms
2-butyne-1,4-diol [10] and the chekered arrangement of of two opposite alcohol groups in the hydrogen bonds
the methoxyl groups –ëç2éç about triple bond (Fig. 3) with the Cl atoms (H(2)···Cl(1) 2.20 Å [11],
changes to “eclipsed” arrangement. In this case, the which strongly link the fragment of two complex
bond angles ë(1)–ë(2)≡ë(3) and ë(4)–ë(3)≡ë(2) anions
into
centrosymmetric
dimers
decrease to 165.6(4)° and 165.3(5)°, respectively (as {[CuCl2(HOCH2C≡CCH2OH)]–}2. However, unlike
compared to a straight angle typical of noncoordinated Rb[CuCl2(HOCH2C≡CCH2OH)] (modification B)
molecule of 2-butyne-1,4-diol), whereas the C(2)≡C(3) [6], where the analogous dimers lie at right angle to one
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 8 2008

622
SLYVKA et al.
H(2)
H(1)
O(1)
H(4)
O(2)
C(1)
C(4)
C(3)
C(2)
H(6)
H(5)
H(3)
Cu
Cl(2)
Cl(1)
–
Fig. 2. The structure of the [CuCl (HOCH C≡CCH OH)] anion in structure I.
2
2
2
O(2)
H(7)
Cl(2)
H(2)
N(1)
C(6)
H(1)
O(1)
Cl(1)
C(9)
H(13)
H(10)
C(5)
N(1)
H(7)
H(8)
Cl(2)
H(9)
N(2)
O(2)
Cl(1)
Fig. 3. Hydrogen bonds in structure I.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 8 2008

COPPER(I) π-COMPLEXES WITH 2-BUTYNE-1,4-DIOL
623
another, the dimers {[CuCl2(HOCH2C≡CCH2OH]–}2
in I are arranged in stacks along the direction [100]
(Fig. 1).
Table 3. The bond lengths (d) and bond angles (ω) in struc-
ture I
Bond
d, Å
Angle
ω, deg
The electrostatic cation–anion interaction in struc-
ture I has a pronounced direction due to the active par-
ticipation of a six-membered cyclic 2-aminopyridinium
cation in the formation of a strong hydrogen bonding
system N–H···O and N–H···Cl (H(9)···O(2) 1.89,
H(8)···Cl(1) 2.29 Å), which cross links the dimeric
anions to give peculiar framework.
Cu–Cl(1)
2.25(5) Cl(1)CuCl(2)
2.24(4) Cl(1)Cum
2.01(8) Cl(2)Cum
2.01(4) C(2)CuC(3)
1.92(7)
107.8(1)
126.2(4)
125.9(2)
35.2(3)
Cu–Cl(2)
Cu–C(2)
Cu–C(3)
Thus, as compared to spherical alkali metal cations
or highly symmetric ammonium cation, the planar
2-aminopyridinium cations with asymmetric distribu-
tion of the positive charge in the pyridine ring are inca-
pable of radical changing of the packing type of the
complex anions, but affect the parameters of the copper
π-coordination core as compared to the previously
stided compounds M[CuCl2(HOCH2C≡CCH2OH)]
Cu–m*
C(2)≡C(3)
C(1)–C(2)
C(3)–C(4)
C(1)–O(1)
C(4)–O(2)
N(1)–C(5)
N(1)–C(9)
N(2)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
H(1)···Cl(2)
H(2)···Cl(1)
H(8)···Cl(1)
H(9)···O(2)
H(7)···Cl(2)
H(13)···Cl(1)
H(10)···O(1)
1.22(2) O(1)C(1)C(2)
1.49(1) C(1)C(2)C(3)
1.48(4) C(2)C(3)C(4)
1.42(7) C(3)C(4)O(2)
1.40(6) C(1)O(1)H(1)
1.35(3) C(4)O(2)H(2)
1.372(8)
112.5(4)
165.6(4)
165.3(5)
111.3(6)
108.9(4)
108.0(5)
(M = NH+4 , K+, Rb+), space groups Ibam [5, 6] and
(ImH)[CuCl2(HOCH2C≡CCH2OH)] [8].
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RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 8 2008