Specific features of the structures of iron(II) α-benzyl dioxymate solvates with pyridine

Article abstract of DOI:10.1134/S0036023610070090

Coordination compounds [Fe(DfgH)₂Py₂] (I) and [Fe(DfgH)₂Py₂] · A, where DfgH is the α-benzyldioxime monoanion and A = Py (II), DMF (III), and methyl ethyl ketone (IV), have been synthesized and studied by X-ray

Full text of DOI:10.1134/S0036023610070090

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2010, Vol. 55, No. 7, pp. 1042–1051. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © I. Bulhac, P.N. Bouros, O.A. Bologa, V. Lozan, O. Ciobanic , J. Lipkowski, T.F. Mitina, Yu.A. Simonov, 2010, published in Zhurnal Neorganicheskoi
a
,
Khimii, 2010, Vol. 55, No. 7, pp. 1111–1121.
COORDINATION COMPOUNDS
Specific Features of the Structures of Iron(II)
α
ꢀBenzyl Dioxymate Solvates with Pyridine
I. Bulhaca, P. N. Bouros b, O. A. Bologaa, V. Lozana, O. Ciobanicaa
,
,
J. Lipkowskic, T. F. Mitinaa, and Yu. A. Simonovb
a Institute of Chemistry, Academy of Sciences of Moldova, Chisinau, Moldova
b Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Moldova
c Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
Received December 18, 2008
Abstract—Coordination compounds [Fe(DfgH)2Py2] (
I
) and [Fe(DfgH)2Py2]
⋅
A, where DfgH is the
α
ꢀbenzyldioxime monoanion and A = Py (II), DMF (III), and methyl ethyl ketone (IV), have been syntheꢀ
sized and studied by Xꢀray diffraction analysis. Diamagnetism and the gammaꢀresonance (GR) spectral
parameters confirm that iron exists in the oxidation state +2 in the lowꢀspin state. The octahedral trans conꢀ
figuration of the iron polyhedra is a common feature of all complexes. The equatorial plane of the octahedron
contains two intramolecular hydrogen bonds O–H…O between two organic anions DfgH– affording a
pseudomacrocycle. The axial coordinate of the octahedron is occupied by the pyridine molecules, which are
almost perpendicular to the equatorial plane N4(oxime) in complexes
I–IV. The structure of the compounds
is a framework with allowance for weak interactions C–H…O and C–H…C. The manner of inclusion of solꢀ
vents into the crystal and their functioning in structure formation of compounds II
–IV are discussed.
DOI: 10.1134/S0036023610070090
L.A. Chugaev pioneered in studying the complex hydrogen bonds of the О–Н···О type and, correspondꢀ
formation of ꢀdioximes ( ꢀDioxH2) with transition ingly, no pseudomacrocycles are formed in such comꢀ
metals, including iron [1]. The coordination of the
central atom in the ꢀdioximate complexes is mainly
α
α
plexes. Under these conditions, nickel(II), cobalt(II),
copper(II), and iron(II) form with ꢀDioxH2 monoꢀ
α
α
defined by the nature of the complexing metal: square
for nickel(II) [2–4], platinum(II) [5–7], pallaꢀ
dium(II) [6, 8], and cobalt(II) [9]; squareꢀpyramidal
(dimeric) for copper(II) [10, 11]; octahedral for
cobalt(III) [12–17], iron(II) [18–21], and iron(III)
[22]. A new method for the synthesis of iron(II) dioxꢀ
imates with biologically active ligands, including
potentially polydentate pyridine derivatives, has been
described [23, 24]. Coordination compounds with
transition metals synthesized under the conditions
providing the deprotonation of the
cules are characterized by the general structural archiꢀ
tecture: two singleꢀcharge organic ligands (
ꢀDioxH–
lie nearly in one plane, coordinating the metal through
the nitrogen atoms to form the central core МN4
which results in the formation of two fiveꢀmembered
metallocycles. This structure is stabilized by two
intramolecular hydrogen bonds of the О–Н···О type
between the organic ligands, thus creating two pseudoꢀ
sixꢀmembered metallocycles. As a whole, they form
one pseudomacrocycle. Similar architecture was
found in the square transition metal complexes [2–9].
This architecture also forms the base for tetragonal
pyramids in copper(II) dimers [10, 11] and is observed
in the equatorial part of octahedral complexes [12–
22]. In an acidic medium, the deprotonation of
meric cisꢀdioximines [25, 26] and tris(dioximines)
[27–29]. In the presence of KI, Cu(II) is reduced to
Cu(I) with the formation of the 1D polymer
[Cu(NioxH2)I]∞ (NioxH2 is 1,2ꢀcyclohexanediꢀ
onedioxime) in which the iodide anions act as bridges
and the polyhedron of the metal atom is a tetrahedron
[30]. Although the structure of metal cisꢀ and
tris(dioximines) remains octahedral, it differs substanꢀ
tially from that of traditional dioximates: there are no
intramolecular hydrogen bonds О–Н···О between
α
ꢀDioxH2 moleꢀ
α
ꢀDioxH2; two and three molecules in the case of cisꢀ
dioximines and tris(dioximines), respectively, lie in
two and three mutually perpendicular planes.
α
)
The iron(II) atom in [Fe(DfgH)2Py2] (
I) and
,
[Fe(DfgH)2Py2] · DMF (III) (DfgH2 is ꢀbenzylꢀ
α
dioxime) is easily oxidized by such oxidants as Сl2
[31], Br2 [32], and I2 [33] to form [Fe(DfgH)2Py2]X
(X = Cl– · Cl2, Br3–, I–5 ). This process is reversible [33,
34]. However, it should be mentioned that, in all cases,
the reduction of [Fe(DfgH)2Py2]X affords complex I as
hexagonal cherryꢀcolored plates resembling crystals of
compound III in shape and color and substantially difꢀ
ferent from Chugaev’s compound of the same formula
[Fe(DfgH)2Py2] (Ia) (dark brown, almost black elonꢀ
α
ꢀDioxH2 is hindered and, hence, no intramolecular gated prisms). In an excess of pyridine and methyl
1042

SPECIFIC FEATURES OF THE STRUCTURES OF IRON(II)
1043
Table 1. Crystallographic data and experimental characteristics for structures I–IV
I
II
III
IV
FW
692.55
Orthorhombic
Pbca
771.65
838.74
836.75
Crystal system
Space group
Unit cell parameter
Monoclinic
Monoclinic
Monoclinic
P
21/
c
C
2/c
C2/m
a
, Å
11.4207(8)
16.5160(10)
17.657(2)
90
9.024(1)
11.482(2)
18.719(3)
102.69(2)
1892.2(8)
2
13.8600(4)
10.0030(4)
30.168(1)
92.037(2)
4179.9(3)
4
10.185(2)
13.825(1)
15.559(2)
107.523(11)
2089.1(5)
2
b,
c,
Å
Å
β
V
Z
,
deg
, Å3
3330.5(5)
4
ρcalcd, g/cm3
1.381
1.354
1.333
1.330
μ
, mm–1
0.504
0.452
0.419
0.418
F(000)
1440
804
1760
880
Crystal sizes, mm
θ range, deg
0.20
×
0.20
×
0.10
0.30
×
0,20
×
0.10
0.25
×
0.20
×
0.10
0.22
×
0.22 × 0.07
2.31–26.07
2.23–25.50
2.83–23.23
2.59–26.21
Reflection index ranges
–14
–20
–21
≤
≤
≤
h
k
l
≤
≤
≤
14
20
21
–10
–13
–22
≤
≤
≤
h
k
l
≤
≤
≤
10
13
22
–15
–11
–33
≤
≤
≤
h
k
l
≤
15
11
33
–12
–17
–19
≤
h
≤
9
≤
≤
k
≤
15
≤
≤
l ≤ 19
Number of measured/indepenꢀ
dent reflections
25176/3284
14168/3386
17913/2978
[Rint = 0.1078]
4456/2153
[
R
int = 0.0577]
[
R
int = 0.0455]
[
R
int = 0.0324]
Number of reflections with
2008
2107
2357
1754
I
> 2σ(I)
Number of refined parameters
GOOF
223
250
268
152
0.796
1.002
1.150
0.944
R
(I
> 2
σ
(
I
))
R
1 = 0.0337
R
1 = 0.0411
R
1 = 0.0792
R
1 = 0.0486
wR2 = 0.0742
wR2 = 0.0890
wR2 = 0.1542
wR2 = 0.1216
R (over the whole set)
ρmin, eÅ–3
R
1 = 0.0604
R
1 = 0.0660
R
1 = 0.1017
R1 = 0.0622
wR2 = 0.1281
wR2 = 0.0784
wR2 = 0.0922
wR2 = 0.1634
Δ
ρmax
,
Δ
0.390, –0.320
0.355, –0.231
0.655, –0.333
1.080, –0.355
ethyl ketone (MEK), [Fe(DfgH)2Py2] · Py (II) and 0.33 mmol) was dissolved in pyridine (4 mL) (solution 2),
and sodium acetate trihydrate (0.027 g, 0.20 mmol)
was dissolved in methanol (20 mL) (solution 3). Soluꢀ
tions 2 and 3 were alternately added in small portions
to solution 1 with continuous stirring. A vessel with the
cherryꢀcolored solution was left closed. Single crystals
as black octahedra were formed after two months.
[Fe(DfgH)2Py2] · CH3C(O)C2H5 (IV
are formed. The crystals of pyridine products
differ in color and shape from one another and from
Chugaev’s complex Ia, which appears, most likely,
due to the effect of solvent molecules on the formation
of the crystal structure. The coordination compounds
)
, respectively,
I–IV
Compound I was obtained in a yield of 0.075 g. The
yield based in FeCl2 · 4H2O was 65%.
containing the same iron(II) complex (
logues with different solvents, namely, Py (II), DMF
III), and MEK (IV), were synthesized to elucidate
the role of the solvent in the architecture of the crysꢀ
I) and its anaꢀ
(
For C38H32FeN6O4 anal. calcd. (%): C, 65.84; H,
4.65; N, 12.13; Fe, 8.06.
tals. The crystal structures of compounds
determined by Xꢀray diffraction analysis.
I–IV were
Found (%): C, 65.60; H, 5.02; N, 12.20; Fe, 8.02.
Synthesis of compound II. Iron(II) chloride tetraꢀ
chloride (0.4 g, 2.012 mmol) was dissolved in methaꢀ
EXPERIMENTAL
nol (10 mL). A warm solution of
α
ꢀbenzyldioxime
Synthesis of compound I. Iron(II) chloride tetrahyꢀ (0.96 g, 4.0 mmol) in pyridine (10 mL) was added to
drate (0.033 g, 0.17 mmol) was dissolved in methanol the obtained solution. Crystals as elongated dark
(25 mL) (solution 1),
α
ꢀbenzyldioxime (0.08 g, brown prisms were formed after ~15 min. The final
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

1044
BULHAC et al.
Table 2. Selected interatomic distances (d) and bond angles (ω) in structures I–IV
I
II
III
IV
Bond
Fe(1)–N(1)
d
, Å
1.906(2)
1.897(2)
2.027(2)
1.353(2)
1.317(3)
1.370(2)
1.313(3)
1.479(3)
1.486(3)
1.481(3)
1.348(3)
1.375(3)
1.370(4)
1.378(4)
1.373(3)
1.345(3)
1.904(2)
1.896(2)
2.018(2)
1.364(2)
1.310(3)
1.363(2)
1.304(3)
1.484(3)
1.474(3)
1.491(3)
1.327(4)
1.376(5)
1.340(5)
1.356(5)
1.374(4)
1.338(4)
1.891(4)
1.892(4)
1.999(5)
1.366(5)
1.317(7)
1.373(5)
1.308(7)
1.483(8)
1.475(7)
1.482(8)
1.348(7)
1.376(9)
1.369(9)
1.382(9)
1.383(9)
1.344(7)
1.896(2)
–
Fe(1)–N(2)
Fe(1)–N(3)
N(1)–O(1)
N(1)–C(1)
N(2)–O(2)
N(2)–C(2)
C(1)–C(11)
C(1)–C(2)
2.007(3)
1.358(2)
1.308(3)
–
–
1.487(3)
1.475(4)
–
C(2)–C(21)
N(3)–C(31)
C(31)–C(32)
C(32)–C(33)
C(33)–C(34)
C(34)–C(35)
N(3)–C(35)
1.345(3)
1.382(4)
1.382(3)
1.382(9)
–
–
II
III
IV
Bond
d
, Å
Bond
d
, Å
Bond
d, Å
N(4)–C(3)
1.321(5)
1.331(5)
1.325(5)
1.325(5)
1.325(5)
O(3)–C(5)
N(4)–C(5)
N(4)–C(4)
N(4)–C(3)
1.25(1)
1.32(1)
1.41(1)
1.46(1)
O(3)–C(5)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
1.26(1)
1.38(2)
1.33(2)
1.34(1)
C(3)–C(4)
N(4)–C(4)#2
C(4)–C(5)#2
C(4)–N(4)#2
I
II
III
IV
Angle
ω
, deg
N(1)Fe(1)N(2)
N(1)Fe(1)N(2)#1
N(1)Fe(1)N(3)
N(1)Fe(1)N(3)#1
N(2)Fe(1)N(3)
N(2)Fe(1)N(3)#1
O(1)N(1)Fe(1)
C(1)N(1)Fe(1)
O(2)N(2)Fe(1)
C(2)N(2)Fe(1)
C(31)N(3)Fe(1)
C(35)N(3)Fe(1)
O(1)N(1)C(1)
O(2)N(2)C(2)
N(1)C(1)C(2)
N(1)C(1)C(11)
C(2)C(1)C(11)
80.74(7)
99.26(7)
87.16(7)
92.84(7)
88.17(7)
91.83(7)
122.2(1)
117.1(1)
122.4(1)
117.9(1)
121.0(2)
121.9(2)
119.8(2)
119.7(2)
111.9(2)
124.4(2)
123.4(2)
80.87(8)
99.13(8)
89.62(8)
90.38(8)
89.86(9)
90.14(9)
80.7(2)
99.3(2)
98.80(11)
81.20(11)
88.57(8)
91.43(8)
–
88.7(2)
91.3(2)
89.1(2)
90.9(2)
–
122.4(2)
117.2(2)
122.6(1)
117.1(2)
123.8(2)
122.2(2)
119.7(2)
120.1(2)
111.5(2)
124.8(2)
123.1(2)
122.9(3)
117.9(4)
122.3(3)
117.8(3)
122.3(4)
121.3(4)
119.1(4)
119.8(4)
111.3(5)
123.1(5)
125.5(5)
122.9(1)
117.0(2)
–
–
121.5(2)
–
119.9(2)
–
112.3(1)
122.9(2)
124.5(1)
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

SPECIFIC FEATURES OF THE STRUCTURES OF IRON(II)
1045
Table 2. (Contd.)
I
II
III
IV
Angle
ω
, deg
C(1)C(11)C(12)
C(1)C(11)C(16)
N(2)C(2)C(1)
122.0(2)
119.4(2)
111.7(2)
124.3(2)
123.9(2)
120.2(2)
121.3(2)
116.8(2)
122.8(2)
120.0(3)
117.6(2)
120.1(3)
122.7(2)
121.9(3)
118.9(3)
112.8(2)
124.0(2)
123.0(2)
120.0(3)
121.4(3)
114.0(3)
124.5(3)
120.6(3)
116.6(3)
120.3(3)
124.0(3)
122.8(5)
117.6(5)
112.2(5)
122.0(5)
125.6(5)
122.0(5)
119.0(5)
116.3(5)
123.3(6)
119.4(6)
118.8(6)
118.5(6)
123.7(6)
121.9(2)
118.9(2)
–
N(2)C(2)C(21)
C(1)C(2)C(21)
C(2)C(21)C(22)
C(2)C(21)C(26)
C(31)N(3)C(35)
N(3)C(31)C(32)
C(31)C(32)C(33)
C(32)C(33)C(34)
C(33)C(34)C(35)
N(3)C(35)C(34)
–
–
–
–
116.8(3)
123.3(2)
119.1(3)
118.3(4)
–
–
IV: N2 = N1#2, N2# = N1#3, C2 = C1#3, C35 = C31#3, C34 = C32#3
II
III
IV
Angle
ω
, deg
Angle
ω
, deg
Angle
ω
, deg
C(3)N(4)C(4)#2
N(4)C(3)C(4)
18.8(4)
120.3(4)
120.9(4)
120.9(4)
C(5)N(4)C(4)
C(5)N(4)C(3)
C(4)N(4)C(3)
O(3)C(5)N(4)
123.2(8)
120.7(8)
116.0(8)
123.0(8)
C(3)C(4)C(5)
C(5)#4C(5)O(3)
O(3)C(5)C(6)
O(3)C(5)C(4)
C(6)C(5)C(4)
145(2)
130.5(7)
119(1)
112(2)
127(1)
C(5)#2C(4)C(3)
N(4)#2C(4)C(3)
* Symmetry codes:
I: #1 –x, –y + 2, –z + 1;
II: #1 –x + 1, –y, –z; #2 –x + 2, –y + 1, –z + 2;
III: #1 –x + 1/2, –y + 1/2, –z;
IV: #1 –x, –y, –z; #2 –x, y, –z; #3 x, –y, z; #4 x, –y + 1, z.
Table 3. Intramolecular hydrogen bond geometry in structures I–IV
Distance, Å
D–H…A
Angle DHA, deg Coordinates of atoms A
D–H
H…A
D…A
I
O(1)–H…O(2)
O(1)–H…O(2)
O(1)–H…O(2)
O(1)–H…O(2)
0.83
0.82
0.82
0.84
1.71
1.73
1.72
1.71
2.517(2)
2.521(2)
2.516(5)
2.517(3)
163
163
162
162
–
–
–
–
x
x
x
x
, –
+ 1, –
+ 1/2, –
, – , –
y
+ 2, –
z
z
+ 1
II
y, –
III
IV
y
+ 1/2, –z
y
z
product was obtained in a yield of 1.46 g. The yield
Found (%): C, 67.13; H, 5.05; N, 12.99; Fe, 7.30.
based on FeCl2 · 4H2O was 94%.
Synthesis of compound III. Iron(II) chloride tetꢀ
For C43H37FeN7O4 anal. calcd. (%): C, 66.91; H, rahydrate (1.0 g, 5.03 mmol) was dissolved in methaꢀ
4.83; N, 12.71; Fe, 7.24. nol (25 mL) (solution 1). ꢀBenzyldioxime (2.4 g,
α
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

1046
BULHAC et al.
C(33)
C(34)
C(32)
C(31)
C(35)
C(22)
C(21)
N(3)
O(2)
C(16)
N(2)
C(2)
C(26)
C(1)
Fe(1)
C(11)
N(1)
C(12)
O(1)
Fig. 1. Structure of the complex [Fe(DfgH) (Py) ] (
I).
2
2
C(33)
C(32)
N(4)
C(31)
C(4)
C(34)
C(35)
C(3)
N(3)
C(16)
C(15)
O(1)
N(1)
Fe(1)
C(11)
C(12)
C(1)
C(26)
N(2)
C(2)
O(2)
C(21)
C(22)
Fig. 2. Structure of the complex [Fe(DfgH) (Py) ] ⋅ Py (II).
2
2
10.0 mmol) and pyridine (1 mL) were dissolved in amount of methanol and diethyl ether, and dried in air.
DMF (25 mL) (solution 2). Solution 2 was added to
solution 1 with continuous stirring. Upon pouring
together these solutions, a finely crystalline product
was formed as hexagonal redꢀcherry plates, which was
separated from the mother liquor, washed with a
The final product was obtained in a yield of 3.20 g. The
yield based on FeCl2 · 4H2O was 83%.
An absorption band at 1670 cm–1 assigned to
ν
(С=О) of DMF appears in the IR spectrum of comꢀ
DMF–methanol (1 : 1) mixture and then with a minor pound III
.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

SPECIFIC FEATURES OF THE STRUCTURES OF IRON(II)
1047
C(33)
C(32)
C(34)
C(31)
C(35)
N(3)
C(16)
O(1)
N(1)
C(11)
C(1)
C(26)
C(21)
Fe(1)
C(12)
O(3)
C(5)
C(2)
N(2)
O(2)
C(22)
N(4)
C(4)
C(3)
Fig. 3. Structure of the complex [Fe(DfgH) (Py) ]
⋅
DMF (III).
2
2
C(33)
C(32)
C(31)
N(3)
C(16)
C(12)
Fe(1)
C(1)
N(1)
C(11)
C(6)
O(1)
C(5)
O(3)
C(4)
C(3)
Fig. 4. Structure of the complex [Fe(DfgH) (Py) ] ⋅ MEK (IV).
2
2
The single crystals suitable for Xꢀray diffraction ular iodine [33] was dissolved in MEK (80 mL). The
were isolated from the mother liquor after its gradual
evaporation in air.
For C41H39FeN7O5 anal. calcd. (%): C, 64.32; H,
5.13; N, 12.81; Fe, 7.29.
solution was filtered off, and a 25% solution of ammoꢀ
nia (1 mL) was added with continuous stirring. Dark
red crystals as large elongated hexagonal plates were
formed after 20–30 min. The final product was
obtained in a yield of 0.8 g. The yield based on
Found (%): C, 65.13; H, 5.15; N, 12.99; Fe, 7.30.
[
Fe(DfgH)2Py2][I5] was 70%.
Synthesis of compound IV. Iron(III) bis(
dioximato)di(pyridine) polyiodide (2.0 g, 1.50 mmol)
obtained by the oxidation of compound
α
ꢀbenzylꢀ
For C42H40FeN6O5 anal. calcd. (%): C, 65.97; H,
I
with molecꢀ 5.27; N, 10.99; Fe, 7.30.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

1048
BULHAC et al.
c
0
b
Fig. 5. Fragment of crystal structure I.
Found (%): C, 65.92; H, 5.01; N, 11.31; Fe, 7.27.
Compounds IV are diagmagnetic. The parameꢀ
reduced to a common scale using the DENZO [37]
and SKALEPACK [37] programs. Absorption correcꢀ
tions were applied by the XEMP program [38]. The
I–
ters of the GR spectra at 300 K are as follows: IS =
0.52–0.56 mm/s, QS = 1.92–1.94 mm/s; at 80 K,
IS = 0.54–0.56 mm/s, QS = 1.93–1.96 mm/s (the
accuracy of IS (relative to sodium pentacyanonitrosylꢀ
ferrate) and QS determination is 0.04 mm/s [17]).
These data confirm that iron exists in the lowꢀspin
state in the oxidation state +2.
structures of compounds I–IV were solved by direct
methods and refined by least squares in the anisotropic
fullꢀmatrix variant for nonꢀhydrogen atoms (SHELXꢀ
97) [39]. Hydrogen atoms were revealed objectively
and refined in the rigid body model.
The crystallographic data and experimental charꢀ
acteristics for structures I–IV are listed in Table 1.
Selected interatomic distances and bond angles are
given in Table 2. The hydrogen bonding geometry is
presented in Table 3. The positional and thermal
parameters for the structures of compounds I–IV were
deposited with the Cambridge Crystallographic Data
Centre (CCDC 706634–CCDC 706637).
GR spectra of the compounds were recorded on a
constant acceleration spectrometer operating in the
time mode. The 57Co isotope in the chromium matrix
at room temperature served as the source. Fine powꢀ
ders of the substances were used as absorbers, whose
thickness was 5–10 mg/cm2 by the natural isotopic
composition.
Xꢀray diffraction analysis. The unit cell parameters
and the reflection intensity sets for crystals of comꢀ
RESULTS AND DISCUSSION
pounds
2T diffractometer (Mo
chromator) at 213, 293, and 173 K, respectively. The
I
,
II, and IV were obtained on a STOE IPDSꢀ
Compounds
I
–
IV can be represented as complexes
Solv, where
IV; Solv is Py for II, DMF for
К
radiation, graphite monoꢀ of general formula [Fe(DfgH)2(Py)2] ·
n
α
n
= 0 for = 1 for II
I,
n
–
experimental data were processed using the STOE III, and MEK for IV. The molecular structures of
XꢀAREA program [35]. For complex III, the experiꢀ compounds IV and the atomic numbering scheme
mental data were obtained at 200 K on a Nonius are shown in Figs. 1–4. The intrinsic symmetry of the
Kappa CCD diffractometer (Mo radiation, graphite complexes is Ci in III and C2h in IV. The iron atoms
scan mode) [36]. The unit cell have the transꢀoctahedral coordination mode similar
I–
К
I–
α
monochromator,
ω θ
ꢀ2
parameters were refined over the whole array of experꢀ to that found in the transition metal complexes of genꢀ
imental data. The intensities were integrated and eral formula [M(DioxH)2A2], where A are neutral
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

SPECIFIC FEATURES OF THE STRUCTURES OF IRON(II)
1049
c
b
0
Fig. 6. Fragment of crystal structure II
.
Fig. 7. Fragment of crystal structure III
.
ligands (pyridine, aniline, thiourea, their derivatives, deprotonated DfgH– ligands, and two nitrogen atoms
belong to two coordinated Py molecules.
and others) [40]. The coordination polyhedron of the
Fe(II) ion in structures IV is formed by six nitrogen
atoms, four of which belong to two bidentate monoꢀ atomic distances are equal, on the average, to
I–
In compounds IV, the Fe(1)–N(dioxime) interꢀ
I–
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

1050
BULHAC et al.
intramolecular hydrogen bonds. In coordinated
ꢀdioximes, the average interatomic distances N–O,
C=N, C–C, and C–C(Ph) are, respectively, 1.361(2),
1.315(3), 1.486(3), and 1.480(3) Å in ; 1.363(2),
α
I
1.307(3), 1.474(3), and 1.487(3) Å in II; 1.370(5),
1.313(7), 1.475(7), and 1.483(8) Å in III; 1.358(2),
1.308(3), 1.475(4), and 1.487(3) Å in IV. They are
close to those found in the Fe(II) complexes with
monodeprotonated
α
ꢀbenzyldioxime and pyridine
c
b
0
derivatives: 1.357(3), 1.308(4), 1.466(4), and 1.482(4)
Å in [Fe(DfgH)2(3ꢀCONH2ꢀPy)2] and 1.356(2),
1.313(3), 1.476(3), and 1.481(3) Å in [Fe(DfgH)2(4ꢀ
COOC2H5ꢀPy)2] [41].
Two pyridine molecules are in the apical positions
of the polyhedra of the central metal atom in strucꢀ
tures I–IV. The dihedral angles between the planes of
the aromatic ring of the latter and the equatorial N4
a
atoms of the corresponding coordination polyhedra
are 99.3
dihedral angle from 90
°
, 90.7°, 94.9
°
, and 95.9
°
. The deviations of the
°
can be due to intermolecular
interactions. The same factor defines the turn of the
plane of the Py ligand about the Fe–N(Py) axis. Simꢀ
ilar arrangement of the
α
ꢀdioximates and neutral
nitrogenꢀcontaining ligands was found in the iron(II)
complexes with imidazole [19], nicotinamide and its
derivative [41], and pyrazine [42]. The interatomic
distances and bond angles in the coordinated Py molꢀ
ecules in structures I–IV do not differ from similar
values found in the Fe(II) complexes with pyridine
derivatives [43, 44].
In compounds
architecture depends only on weak interactions
Н···О and С–Н··· . The structure of compound
is a framework formed only by weak С–Н···О interacꢀ
tions. The twoꢀdimensional network perpendicular to
I–IV, the formation of the crystal
Fig. 8. Fragment of crystal structure IV
.
С
⎯
π
I
1.902(2), 1.900(2), 1.896(2), and 1.891(4) Å, respecꢀ
tively. The Fe(1)–N(Py) bond lengths are 2.027(2),
2.018(2), 2.007(3), and 1.999(5) Å, respectively (Table 2).
In each structure, the coordination octahedron of the
iron atom is slightly elongated in the direction of the
pyridine fragment. Possibly, the shortening of the Fe–
N(dioxime) bond compared to Fe(1)–N(Py) is
defined by both the chelating effect and the formation
of the pseudomacrocyclic structure. The interatomic
the
х
axis of crystal
I
is shown in Fig. 5. Structure II
axis, which form channels
contains chains along the
у
in crystal packing. The channels include randomly
arranged solvation pyridine molecules (Fig. 6) bound
to the complexes through the weak С–Н··· interacꢀ
π
tion. In structure III, the molecular iron(II) comꢀ
plexes form twoꢀdimensional networks with chains of
the DMF solvate molecules between them. The DMF
molecules interact with the complexes to form the
intramolecular hydrogen bonds С–Н···О (Fig. 7). In
distances in compounds
I–IV are close to those found
in Fe(II) complexes with monodeprotonated
zyldioximes and coordinated apical molecules of
pyridine derivatives [41]. The shortening of the
α
ꢀbenꢀ
structure IV, as well as in II, chains along the у axis can
be distinguished, while each cavity formed by the
complexes contains two MEK molecules linked by
intramolecular hydrogen bonds С–Н···О (Fig. 8).
Other intermolecular contacts in structures III and IV
correspond to the sums of the van der Waals radii of the
corresponding atoms.
Fe
Fe(III)
⎯
N(dioxime) bonds is comparable with that in
α
ꢀdioximates [22], which is defined by the
bond redistribution in the pseudomacrocyclic system
of the equatorial fragments conjugated with the aroꢀ
matic rings. Each equatorial plane of complexes
I–IV
contains two ꢀbenzyldioxime residues coordinated
α
Thus, in crystals I–IV, the [Fe(DfgH)2Py2] comꢀ
according to the N,N type, resulting in the formation
of two chelate rings. This mutual arrangement of the
DfgH– residues is fixed by the О–Н…О intramolecular
hydrogen bonds (Table 3). This leads to the fragments
in which the fiveꢀmembered metallocycles alternate
plexes form rather mobile packing of large molecules.
The low energy of rotation of the phenyl radicals about
the C–C bonds and the Py molecules about the Fe–N
bonds allows the aromatic rings to be arranged in such
a way that the crystals would accept the solvate moleꢀ
with the sixꢀmembered pseudocycles formed through cules without considerable changes in their density
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 7 2010

SPECIFIC FEATURES OF THE STRUCTURES OF IRON(II)
1051
19. K. Bowman, A. P. Ganghan, and Z. Dori, J. Am.
(Table 1). The dihedral angles between the planes of
the phenyl rings and metallocycles in compounds II
III, and IV are 50.7 and 46.1 , 50.0 and 115.7
64.7 and 118.1 and 66.6 and 113.4 , respectively.
The dihedral angles between the planes of two phenyl
substituents vary within 52.8 –106.8 . The turns of
the aromatic rings in crystals II IV are defined by the
Chem. Soc. 94 (3), 727 (1972).
I
, ,
°
°
°
°
,
20. Yu. A. Simonov, A. A. Dvorkin, I. I. Bulgak, et al.,
°
°
,
°
°
Koord. Khim. 5 (12), 1883 (1979).
21. Yu. A. Simonov, V. E. Zubareva, I. I. Bulgak, et al.,
°
°
Dokl. Akad. Nauk SSSR 287 (1), 122 (1986).
–
22. A. A. Dvorkin, Yu. A. Simonov, T. I. Malinovskii, et al.,
intermolecular interactions with the solvate moleꢀ
cules. Although the complexes and solvate molecules
Dokl. Akad. Nauk SSSR 234 (6), 1372 (1977).
23. D. G. Batyr and I. I. Bulgak, Izv. Akad. Nauk Moldꢀ
SSR, Ser. Biol. Khim., No. 1, 77 (1971).
of compounds II–IV contain no classical donor groups,
all changes occur against the background of the formaꢀ
…
…
π
24. D. G. Batyr and I. I. Bulgak, Izv. Akad. Nauk Moldꢀ
SSR, Ser. Biol. Khim., No. 3, 71 (1971).
tion of weak interactions С–Н О and С–Н
.
25. Yu. A. Simonov, M. M. Botoshanskii, T. I. Malinovskii,
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