Synthesis and crystal structure of Co(III) dioximates with the complex anion [SbF6]-

Article abstract of DOI:10.1134/S1070328412070068

The complexes [Co(DioxH)₂L₂][SbF₆] · nH₂O, where DioxH is dimethylglyoxime monoanion (DioxH ^□) or 1,2-cyclohexanedione dioxime (NioxH^-), L is aniline (An) or triphenylphosphine (PPh₃

Full text of DOI:10.1134/S1070328412070068

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2012, Vol. 38, No. 8, pp. 545–551. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © E.B. Coropceanu, A.P. Rija, V.I. Lozan, O.A. Bologa, A.A. Boldisor, I.I. Bulhac, V.Ch. Kravtsov, P.N. Bourosh, 2012, published in Koordinatsionnaya
Khimiya, 2012, Vol. 38, No. 8, pp. 575–581.
Synthesis and Crystal Structure of Co(III) Dioximates
with the Complex Anion [SbF6]–
E. B. Coropceanua, A. P. Rijaa, V. I. Lozana, O. A. Bologaa, A. A. Boldisora, I. I. Bulhaca,
,
V. Ch. Kravtsovb, and P. N. Bouroshb *
a Institute of Chemistry, Academy of Sciences of Moldova, Chisinau, Moldova
b Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Moldova
*eꢀmail: bourosh.xray@phys.asm.md
Received August 23, 2011
Abstract—The complexes [Co(DioxH)2L2][SbF6]
DioxH⎯ ) or 1,2ꢀcyclohexanedione dioxime (NioxH–), L is aniline (An) or triphenylphosphine (PPh3), were
isolated from the CoX2 H2O–NaSbF6–DioxH2–L system (X = F or CH3COO) in aqueous methanol. The
complexes were studied by UV, IR, and NMR spectroscopy and by Xꢀray diffraction. The crystal structure of
[Co(DH)2(An)2][SbF6] H2O ) and [Co(NioxH)2(PPh3)2][SbF6] (II) is stabilized by the electrostatic interꢀ
⋅
nH2O, where DioxH is dimethylglyoxime monoanion
(
⋅
n
·
(I
actions between the Co(III) complex cations and outerꢀsphere fluorineꢀcontaining anions and by hydrogen
bonds between structural units.
DOI: 10.1134/S1070328412070068
Transition metal compounds of
α
ꢀdioximes form a reported [17, 18]; but complexes with
α
ꢀdioximes
broad field of coordination chemistry. Their diversity were synthesized for the first time.
is caused by the nature of the metal used, the type of
The complexes [Co(DioxH)2L2][SbF6]
where DioxH– is the dimethylglyoxime monoanion
DH–) or 1,2ꢀcyclohexanedione dioxime (NioxH–),
and L is aniline (An) or triphenylphosphine (PPh3),
were obtained from the CoХ2 H2O–NaSbF6–
DioxH2–L system (X = F or CH3COO) in CH3OH–
H2O. The composition and structure of these comꢀ
pounds were studied by spectroscopy and by
Xꢀray diffraction, which was used for unambiguꢀ
ous determination of the molecular and crystal
⋅
n
H2O
,
dioxime, and additional organic ligands and anions.
The dioxime compounds can also differ by structural
(
features because
α
ꢀdioximates can be prepared as
complex cations or molecular complexes and can be
monomeric, dimeric, or polymeric. The interest in
these compounds has been revived in recent years due
to their physical and chemical properties, which can
account for their applications in analytical chemistry,
extraction processes, magnetic materials, or models of
biological systems [1–5]. A crucial factor of the synꢀ
⋅
n
structures of [Co(DH)2(An)2][SbF6]
[Co(NioxH)2(PPh3)2][SbF6] (II
⋅
H2O (I) and
thesis of transition metal complexes with ꢀdioximes
α
).
is the formation of stable chelates. The diversity of the
obtained Co(III) complexes is determined by both the
conditions of synthesis and the nature of the addiꢀ
tional ligands and anions. The conditions for variation
of their composition and structure and for gaining new
properties are mainly related to the use of ligands axiꢀ
ally coordinated to the metal atom [1–3].
EXPERIMENTAL
Synthesis of I. A solution of NaSbF6 (0.26 g,
1 mmol) in water (10 mL) was added to a solution of
CoF2
and the mixture was heated to
⋅
4H2O (0.17 g, 1 mmol) in hot water (10 mL),
70 . Then a mixture
∼
°
C
In recent years, we have focused attention on the
study of transꢀoctahedral cobalt(III) dioximates
incorporating F–, [Н2F3]– and various fluorineꢀconꢀ
taining anions ([BF4]–, [SiF5]–, [CF3SO3]–, [SiF6]2–,
[BeF4]2–, [ZrF6]2–, [TiF6]2–, [AlF6]3–) [6–16]. The
anions with different steric capacity differ by the numꢀ
ber of atoms that are able to function as hydrogen bond
of dimethylglyoxime (0.23 g, 2 mmol) in methanol
(30 mL) and aniline (1 mL) was added dropwise. The
reaction mixture was kept at a specified temperature
for 10–15 min being oxidized by air oxygen. The
brown solution was filtered and left for slow evaporaꢀ
tion at room temperature. Dark brown prismatic crysꢀ
acceptors and, as a consequence, affect the mode of tals precipitated. Yield ~20%. The compound was solꢀ
packing of components into the crystal. Cobalt(III) uble in DMF, DMSO, and alcohols and less soluble in
compounds with hexafluoroantimonate ion have been water.
545

546
COROPCEANU et al.
RESULTS AND DISCUSSION
For C20H30CoF6N6O5Sb
The compounds
complex cations coordinate the dimethylglyoxime (I)
I
and II are ionic. The Co(III)
anal. calcd., %: Co, 8.08; C, 32.94; H, 4.15; N, 11.53.
Found, %: Co, 7.91; C, 32.82; H, 4.08; N, 11.41.
and 1,2ꢀcyclohexanedione dioxime (II) residues, and
the ligands An and PPh3, respectively, are in the apical
Synthesis of II. 1,2ꢀCyclohexanedione dioxime positions. The counterꢀions are the [SbF6]– anions in
(0.28 g, 2 mmol) and PPh3 (0.52 g, 2 mmol) were disꢀ both compounds. The crystals of
tion water molecules.
In the UV spectrum, the band at 230–250 nm corꢀ
responds to the transition in the Со(DioxH)2
I contain crystallizaꢀ
solved in methanol (50 mL). The solution was heated
on a water bath to 60 . An aqueous solution of
Co(СH3COO)2 4H2O (0.25 g, 1 mmol) and NaSbF6
∼
°
C
⋅
π
– *
π
(0.26 g, 1 mmol) was added dropwise to the mixture of
ligands in such a way that the temperature of the reacꢀ
tion mixture did not drop sharply. The final solution
was heated with a reflux condenser for 1 h, filtered,
and left for slow evaporation at room temperature.
Brown prismatic crystals precipitated from the soluꢀ
tion. Yield ~22%. The compound was soluble in DMF,
DMSO, and alcohols and less soluble in water.
group, while the band at 350–390 nm indicates the
presence of other ligands (An, PPh3) in the 1,6ꢀcoorꢀ
dinate.
The IR spectrum of complex I exhibits absorption
bands at 1610 (CN), 1240 νas(NO), 1091 νs(NO),
ν
517 νas(Co–N), and 432 cm–1 νs(Co–N), which conꢀ
firmed the coordination of dimethylglyoxime to the
central atom. The 742 and 685 cm–1
δ
(CH) absorption
bands typical of a monosubstituted aromatic ring and
the 3264, 3068 (NH) bands
(NH) and 1556 cm–1
ν
δ
For C48H48CoF6N4O4P2Sb
are indicative of aniline position in the apical coordiꢀ
nate. The presence of nioxime in complex II is proved
anal. calcd., %: Co, 5.35; C, 52.34; H, 4.39; N, 5.09.
Found, %:
Co, 5.21; C, 52.11; H, 4.32; N, 4.98.
by the presence of 1668 (CN), 1229 νas(NO), 1087
ν
νs(NO), 511 νas(Co–N), and 427 cm–1 νs(Co–N)
bands in the IR spectrum. The presence of PPh3 molꢀ
ecules in complex II is confirmed by the 2959, 2864
IR spectra of complexes of I and II were recorded
on a 100 FTꢀIR spectrometer in mineral oil at 4000–
400 cm–1 and ATP at 4000–650 cm–1. UV spectra
were measured on a Lambda 25 Perkin Elmer spectroꢀ
ν
(CH); 1435, 1001
ν
(PC); and 751, 683 cm–1
(CH)
δ
bands, which are typical of monosubstituted aromatic
ring.
photometer for aqueous solutions (0.5
×
10–4 mol/L).
The presence of outerꢀsphere hexafluoroantiꢀ
The 19F NMR spectra of [Co(DH)2(Аn)2][SbF6]
⋅
monate ion is indicated by the 19F NMR signal at
H2O were measured on a Brukerꢀ300 MHz spectromꢀ
eter in D2O using СFСl3 as the internal standard.
⎯
118.7 ppm (
δ
[SbF6]–).
The crystals of
I
are composed of centrosymmetric
[Co(DH)2(An)2]+ cations, [SbF6]– anions located on
a twofold axis, and H2O in 1 : 1 : 1 ratio (Fig. 1). The
Co(III) coordination polyhedron is the octahedron
formed by four nitrogen atoms of two dimethylglyꢀ
oxime residues located in one plane and combined by
intraꢀion hydrogen bonds (HB) and by two nitrogen
atoms of two aniline molecules on the axial coordiꢀ
nates. The Co–N interatomic distances are 1.892(2),
1.900(2), and 2.012(2) Å (Table 2) and the donor–
XꢀRay diffraction study of I and II was performed at
room temperature on a STOE IPDS diffractometer
(
Mo
K
radiation,
λ
= 0.71073 Å, graphite monochroꢀ
α
mator,
ω
scan mode). The crystal structures were
solved by the direct method and refined by the leastꢀ
squares method in the anisotropic fullꢀmatrix approxꢀ
imation for nonꢀhydrogen atoms (SHELXꢀ97) [19].
The positions of the oxime and water hydrogen atoms
were found from the difference Fourier maps, the
other were calculated geometrically and refined isoꢀ
tropically in the rigid body model. The crystal data and
acceptor distance in the O–H⋅⋅⋅
2.518(3) Å (Table 3). The mean plane of the aniline
molecules forms an 32.1 angle with the 4N equatorial
plane. This arrangement of these fragments implies
weak interactions between the An aromatic rings
O intraꢀion HB is
°
Xꢀray experiment details for I and II are summarized
in Table 1, the interatomic distances and bond angles
are in Table 2, and the geometric parameters of hydroꢀ
gen bonds are in Table 3. The positional and thermal
π π
–
and the corresponding fiveꢀmembered metal rings
formed by DH– (the distance between the centroids of
the rings is 3.630 Å). In the [SbF6]– anion, the Sb–F
distances (1.884(2)–1.901(2) Å) are consistent with
published data [17, 18, 20].
parameters for structures
the Cambridge Crystallographic Data Centre
(nos. 828210 ( ) and 828211 (II); deposit@ccdc.
I and II are deposited with
I
cam.ac.uk or http://www.ccdc.cam.ac.uk/data_
request/cif).
Along with the electrostatic interactions between
the Co(III) complex cations and outerꢀsphere anions
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SYNTHESIS AND CRYSTAL STRUCTURE OF CO(III) DIOXIMATES
547
Table 1. Crystal data, Xꢀray experiment details, and structure refinement parameters for I and II
Value
Parameter
I
II
M
729.18
213(2)
1101.52
150(2)
T
, K
System
Monoclinic
Monoclinic
Space group
Unit cell parameters:
C
2/c
P21/c
a
, Å
19.9183(12)
8.6607(7)
15.8740(10)
99.544(7)
2700.5(3)
4
9.6182(2)
18.9886(3)
12.9557(4)
107.256(3)
2259.67(9)
2
b,
c,
Å
Å
β
V
Z
ρ
μ
, deg
, Å3
(calcd.), g/cm3
, mm–1
1.794
1.619
1.699
1.111
F
(000)
Crystal size, mm
Range of , deg
1456
1116
0.22
2.57–26.00
24, –10 10, –19
9382/2622 ( int = 0.0522)
×
0.18
×
0.08
0.25
2.70–25.50
11, –23 23, –10
14822/4198 ( int = 0.0371)
×
0.15
×
0.10
θ
Range of reflection indices
–23
≤
h
≤
≤
k
≤
≤
l
≤
18 –11
≤
h
≤
≤
k
≤
≤
l ≤ 15
The number of measured/independent reꢀ
flections
R
R
Filling, %
98.5 (
θ
= 26.00)
99.9 (θ = 25.50)
The number of reflections with
I
> 2σ
(I
)
2003
179
2852
301
The number of refined parameters
GOOF
1.027
1.041
R
R
ꢀfactor (
I
> 2
σ
(
I
))
R
1 = 0.0226, wR2 = 0.0431
1 = 0.0337, wR2 = 0.0436
0.605, –0.330
R
1 = 0.0306, wR2 = 0.0494
1 = 0.0535, wR2 = 0.0511
0.394, –0.590
ꢀfactor (the whole array)
Å–3
R
R
Δρmax, Δρmin, e
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548
COROPCEANU et al.
Table 2. Selected interatomic distances and bond angles for
and II
(Table 3, Fig. 2), the interꢀion hydrogen bonds
between them and also with water molecules substanꢀ
I
*
tially contribute to the formation of crystal structure I.
The NH2 groups of the coordinated aniline molecules
of the complex cations form the interꢀion HB with the
Complex cations
, Å
Bond
d
F(2) atom of the [SbF6]– anions (
N
⋅⋅⋅F 2.990(3) Å)
and with oxygen of the crystallization water molecule
⋅⋅⋅O(1 ) 2.984(3) Å). In turn, the water molecule
forms the О(1 )–H⋅⋅⋅ interꢀion HB with the oxime
oxygen atom of the complex cation ( ⋅⋅⋅О 2.934(2) Å)
and the О(1 )–H⋅⋅⋅
interꢀion HB with the [SbF6]–
anion ( ⋅⋅⋅F 3.101(3) Å). The crystal of also contains
weak С–H⋅⋅⋅ interꢀion HB between the phenyl group
I
II
Co(1)–N(1)
Co(1)–N(2)
Co(1)–N(3)/P(1)
N(1)–C(1)
N(1)–O(1)
N(2)–C(2)
N(2)–O(2)
C(1)–C(2)
C(1)–C(4)/C(6)
C(2)–C(3)
1.892(2)
1.900(2)
2.012(2)
1.300(3)
1.345(3)
1.293(3)
1.352(3)
1.473(4)
1.493(4)
1.490(4)
1.888(2)
1.882(2)
2.3569(7)
1.306(3)
1.335(2)
1.297(3)
1.359(2)
1.453(3)
1.488(3)
1.486(3)
(
N
w
w
О
О
w
F
О
I
F
of the An cation and the anion (С(8)⋅⋅⋅F(1) 3.402 Å).
The crystals of compound II are composed of cenꢀ
trosymmetric [Со(NioxH)2(РРh3)2]+ cations and the
[SbF6]– anions (Fig. 3). The equatorial plane of the
complex cation accommodates two 1,2ꢀcyclohexꢀ
anedione dioxime residues, while two triphenylphosꢀ
phine molecules are located in the apical coordinates.
The Co(III) coordination polyhedron is formed by
four nitrogen atoms of two NioxH– ligands and two
phosphorus atoms of РРh3. The monodeprotonated
ω
, deg
Angle
I
II
N(1)Co(1)N(2)
81.26(9)
89.33(9)
88.56(8)
98.74(9)
90.67(9)
91.44(8)
121.3(2)
116.7(2)
122.0(2)
119.3(2)
116.8(2)
123.9(2)
112.6(2)
122.5(2)
124.9(3)
112.6(2)
123.0(2)
124.4(2)
81.42(9)
92.12(6)
91.33(6)
98.58(9)
87.88(6)
88.67(6)
121.8(2)
115.8(2)
122.4(2)
118.3(2)
116.9(2)
124.7(2)
113.2(2)
125.0(2)
121.7(2)
112.2(2)
125.5(2)
122.3(2)
N(1)Co(1)N(3)/P(1)
N(2)Co(1)N(3)/ P(1)
N(1)Co(1)N(2)#1
N(1)Co(1)N(3)#1/P(1)#1
N(2)Co(1)N(3)#1/P(1)#1
C(1)N(1)O(1)
C(1)N(1)Co(1)
O(1)N(1)Co(1)
C(2)N(2)O(2)
C(2)N(2)Co(1)
O(2)N(2)Co(1)
N(1)C(1)C(2)
N(1)C(1)C(4)/C(6)
C(2)C(1)C(4)/C(6)
N(2)C(2)C(1)
NioxH– ions are combined by two intraꢀion HB (
О О
⋅⋅⋅
2.539(2) Å). The cyclohexane moiety of the NioxH–
ligand is in the halfꢀchair conformation with the C(4)
and C(5) atoms being shifted by 0.202 and 0.466 Å,
respectively, to different sides of the mean plane of the
C(1)C(2)C(3)C(6) atoms, which is a typical feature of
such complexes [12, 14]. The Co–N interatomic disꢀ
tances are 1.888(2) and 1.882(2) Å and the Co–P disꢀ
tances are 2.3569(7) Å. The Co–P bond lengths in II
differ by 0.1 Å from these bonds found in dioximes
containing one coordinated РРh3 molecule (e.g., the
[Со(DН)2(РРh3)(H2О)]+ cation [16]) but are roughly
equal to the bonds found in this type of complexes with
N(2)C(2)C(3)
C(1)C(2)C(3)
Complex anions
, Å
Bond
d
two РРh3 molecules [7, 12]. In the РРh3 ligands of II
the P–C interatomic distances are 1.824(3)–
1.829(2) Å and the CPC bond angles are 100.4(1)
110.70(8) The interatomic distances (2.946–
,
I
II
Sb(1)–F(1)
Sb(1)–F(2)
Sb(1)–F(3)
1.884(2)
1.901(2)
1.884(2)
1.886(2)
1.895(2)
1.883(2)
°
–
°
.
3.103 Å) between the carbon atoms of the РРh3 phenyl
ω
, deg
groups and the oxygen atoms of the NioxH– oxime
Angle
I
II
groups suggest the formation of weak С–Н⋅⋅⋅O intraꢀ
F(1)Sb(1)F(2)
F(1)Sb(1)F(3)
F(2)Sb(1)F(3)
F(1)Sb(1)F(1)#2
F(1)Sb(1)F(2)#2
F(1)Sb(1)F(3)#2
F(2)Sb(1)F(2)#2
F(2)Sb(1)F(3)#2
F(3)Sb(1)F(3)#2
92.18(8)
179.13(10)
87.06(8)
88.0(1)
91.82(8)
91.56(10)
174.43(11)
88.96(8)
88.9(2)
89.31(8)
89.25(9)
90.13(8)
ion HB.
The Sb–F bond lengths in the [SbF6]– anions of II
(1.883(2)–1.895(2) Å) do not differ from those found
180
90.69(8)
90.75(9)
89.87(8)
89.87(8)
in
I. Although the outerꢀsphere anion in II does not
form strong interꢀion HB as in
able contribution to the packing of components in the
crystal, as all fluorine atoms are involved in weak interꢀ
ion HB, С(Рh)–H⋅⋅⋅F (С⋅⋅⋅F 3.319–3.381
I
, it makes a considerꢀ
180
Å) (Fig. 4).
#1
* Symmetry code for equivalent atoms: for
I
, –z
:
–
–
x
x
, –
y
+ 1, –
z
+ 2,
+ 1.
#2
#1
#2
In the crystal structure of and II, electrostatic
interactions between the complex cations and anions
I
–x,
y, –z
+ 3/2; for II
:
–x
+ 1, –
y
,
+ 2, –
y, –z
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SYNTHESIS AND CRYSTAL STRUCTURE OF CO(III) DIOXIMATES
549
Table 3. Geometric parameters of intraꢀ and intermolecular hydrogen bonds in
I
and II
Distance, Å
Coordinates
of A atoms
D–H⋅⋅⋅A contact
DHA angle
D–H
H⋅⋅⋅A
D⋅⋅⋅A
I
O(2)–H(1)⋅⋅⋅O(1)
0.96
0.91
0.91
1.01
1.01
1.59
2.08
2.09
2.19
2.26
2.518(3)
2.984(3)
2.990(3)
3.101(3)
2.934(2)
160
177
171
150
123
–x, –y + 1, –z + 2
N(3)–H(1)⋅⋅⋅O(1
w
)
x
,
,
y
y
,
,
z
z
N(3)–H(2)⋅⋅⋅F(2)
x
x
O(1
w
w
)–H(1)⋅⋅⋅F(1)
)–H(1)⋅⋅⋅O(2)
x
,
y
+ 1,
z
O(1
, y, z
II
O(2)–H(1)⋅⋅⋅O(1)
0.82
1.76
2.539(2)
159
–x + 1, –y, –z
Sb(1)
F(3)
F(2)
F(1)
C(7)
C(6)
C(8)
C(5)
C(9)
O(1w)
C(10)
N(3)
O(1)
C(4)
C(1)
N(1)
N(2)
Co(1)
C(3)
C(2)
O(2)
Fig. 1. Structure of the components of
I
and atom numbering.
No. 8 2012
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 38

550
COROPCEANU et al.
x
y
0
z
Fig. 2. Fragment of crystal structure I.
O(1)
N(1)
C(1)
C(6)
Co(1)
C(4)
N(2)
C(2)
C(5)
C(3)
O(2)
C(12)
F(3)
P(1)
C(14)
C(11)
C(19)
C(13)
F(2)
F(1)
C(15)
C(7)
C(8)
Sb(1)
C(24)
C(16)
C(10)
C(23)
C(20)
C(21)
C(18)
C(9)
C(17)
C(22)
Fig. 3. Structure of the components of II and atom numbering.
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SYNTHESIS AND CRYSTAL STRUCTURE OF CO(III) DIOXIMATES
551
x
0
z
y
Fig. 4. Fragment of crystal structure II
.
9. Bourosh, P.N., Koropchanu, E.B., Simonov, Yu.A.,
et al., Russ. J. Coord. Chem., 2002, vol. 28. no. 9, p. 647.
10. Bourosh, P.N., Bologa, O.A., Simonov, Yu.A., et al.,
are supplemented by interꢀion HB, including weak
С–H⋅⋅⋅ bonds.
F
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RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 38
No. 8
2012