Synthesis and crystal structure of one-dimensional azide-bridged Mn(III) polymer [Mn(BrSal2MePn)(μ1,3-N3)] n (BrSaI2MePn = N,N′-bis(salicylidene)-1,2- propanediamine)

Article abstract of DOI:10.1134/S1070328411070074

A new one-dimensional manganese(III) Schiff base complex [Mn(BrSal ₂MeCrossed D signn)(μ_1,3-N₃)] _n (I) was synthesized by the reaction of MnCl₂ ? 6H₂O with the Schiff base ligand H₂BrSal₂MeCrossed D signn condensed from 2,2-dimethylpropylenediamine with 5-bromosalicylaldehyde and was characterized by elemental analyses and FT-IR spectroscopy. The molecular structure of I has been determined from single-crystal X-ray diffraction analysis. In this structure, the Mn³⁺ ion is in a distorted octahedral geometry with an obvious Jahn-Teller effect, where the deprotonated tetradentate Schiff-base ligand BrSal₂MePn^2- is bound in the equatorial plane and the N ₃ ^- anions show μ_1,3-bridging mode in the axial direction.

Full text of DOI:10.1134/S1070328411070074

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 7, pp. 518–522. © Pleiades Publishing, Ltd., 2011.
Synthesis and Crystal Structure of OneꢀDimensional AzideꢀBridged
Mn(III) Polymer [Mn(BrSal2MePn)(µ1,3ꢀN3)]n (BrSaI2MePn =
N,N'ꢀBis(salicylidene)ꢀ1,2ꢀpropanediamine)1
A. D. Khalajia, * and S. Trikib
a Department of Chemistry, Faculty of Science, Golestan University, Gorgan, Iran
b UMR CNRS 652J, Universite de Bretagne Occidentale, Brest Cedex, 29285 France
*eꢀmail: alidkhalaji@yahoo.com; ad.khalaji@gu.ac.ir
Received August 31, 2010
Abstract—A new oneꢀdimensional manganese(III) Schiff base complex [Mn(BrSal2MeÐn)(μ1,3ꢀN3)]n (
was synthesized by the reaction of MnCl2 · 6H2O with the Schiff base ligand H2BrSal2MeÐn condensed from
2,2ꢀdimethylpropylenediamine with 5ꢀbromosalicylaldehyde and was characterized by elemental analyses and
I)
FTꢀIR spectroscopy. The molecular structure of I has been determined from singleꢀcrystal Xꢀray diffraction
analysis. In this structure, the Mn3+ ion is in a distorted octahedral geometry with an obvious Jahn–Teller
effect, where the deprotonated tetradentate Schiffꢀbase ligand BrSal2MePn2– is bound in the equatorial
−
N3
plane and the
anions show μ1,3ꢀbridging mode in the axial direction.
DOI: 10.1134/S1070328411070074
1
INTRODUCTION
Herein we report the synthesis and crystal structure a
of new oneꢀdimensional manganese(III) Schiff base
complex [Mn(BrSal2MeРn)(μ1,3ꢀN3)]n (I).
In recent years extensive studies have been focused
on the chemistry of manganese(III) complexes with
Schiffꢀbase ligands because of their growing interest in
the field of molecular magnetism [1], metalloenzymes
[2], and inhibitors of xanthine oxidase [3] and in
understanding their catalytic activities in many
organic reactions [4]. These complexes have highꢀspin
ground state and apparent magnetic anisotropy and
are among the complexes acting as paramagnetic
building blocks for constructing expanded structures
with appealing magnetic properties [5].
EXPERIMENTAL
All reagents and solvents for synthesis and analysis
were commercially available and used as received
without further purifications. Infrared spectra were
recorded using KBr disks on a FTꢀIR PerkinElmer
spectrophotometer. Elemental analyses were carried
out using a Heraeus CHNꢀOꢀRapid analyzer.
Oneꢀdimensional manganese(III) Schiff base comꢀ
plexes are of particular interest in the field of molecular
magnetism [6–11]. These complexes are generally found
to exhibit both weak antiferromagnetic [6, 7] and ferroꢀ
magnetic [8–11] interaction. To date, an increasing
number of manganese(III) coordination polymers based
on tetradentate Schiff base ligands bridged by conjugated
small groups, such as cyano, oxalate, nitride, and azido,
have been reported [6–11]. Among these short bridging
ligands, in particular, the azide ion exhibits versatile
bridging mode, such as μ1,1 [12], μ1,3 [13], and rarely
μ1,1,3,3 [14]. However, to the best of our knowledge, the
azidoꢀbridged manganese(III) complexes are very rare
and only few examples have been reported [6–11]. This
study is part of our ongoing effort to synthesize and charꢀ
acterize an extensive series of manganese(III) complexes
with the N2O2 Schiffꢀbase ligand [15, 16].
Synthesis of complex I. H2BrSal2MeРn was prepared
by the condensation of 2,2ꢀdimethylpropylenediamine
with 5ꢀbromosalicylaldehyde following the literature
methods [17]. The solid yellow Schiff base ligand
[H2BrSal2MeРn] (0.468 g, 1 mmol) was dissolved in a
1 : 1 methanol–acetone mixture (20 ml) with vigorous
stirring. A methanolic solution (10 ml) of MnCl2 · 2H2O
(0.322 g, 2 mmol) was added to the stirred solution of
H2BrSal2MeРn and was further stirred for 2 h at room
temperature. An aqueous solution (5 ml) of sodium azide
(0.65 g, 10 mmol) was slowly added dropwise to the above
solution resulting in the precipitation of a small amount
of a brown coloured solid that redissolved upon complete
addition of the sodium azide solution. The resulting soluꢀ
tion was stirred for 20 min at room temperature and filꢀ
tered. The filtrate was left at room temperature (at 25°C).
Dark brown single crystals of I suitable for Xꢀray analysis
were obtained after several days by slow evaporation of
1
The article is published in the original.
518

SYNTHESIS AND CRYSTAL STRUCTURE
519
Table 1. Crystallographic data and experimental details for
complex
solvents at room temperature, then collected by filtraꢀ
tion, and dried in vacuo. The yield was 81%.
I
Parameter
Value
For C38H36Br4Mn2N10O4
Molecular weight
1126.29
anal. calcd., %: C, 40.52;
Found, %: C, 40.66;
H, 3.22;
H, 3.31;
N, 12.44.
N, 12.84.
Crystal system, space group
Monoclinic, P21/c
a
, Å
, Å
12.6445(4)
12.8920(5)
12.4737(6)
90.603(4)
2033.26(14)
2
IR (KBr;
, cm–1): 2869–2966 (C–H aliphatic and
aromatic), 2048 s (N3), 1619 s (C=N), 1455–1589 (C=C
aromatic), 1290 s (C–O), 463 s (Co–N), 418 s (Co–O).
ν
b
c
, Å
β
V
Z
, deg
Caution! Although we did not experience any problem
during the work, perchlorateꢀ and azideꢀcontaining
compounds being potentially explosive, such compounds
,
Å3
–3
should be used in small quantities and handled with great ρcalcd, g cm
1.840
–1
care.
µ
, mm
4.61
Xꢀray structure determination. A single crystal of
I
F
(000)
1112
was placed at the top of a glass fiber with silicone
grease and mounted on an Xcalibur 2 CCD diffractoꢀ
meter (Oxford Diffraction) fitted with a graphite
Reflections measured
, deg
11698
θ
/
θ
2.8/31.8
5977/0.060
2480
min max
Reflections unique/Rint
monochromated Mo
K
radiation ( = 0.71073 Å).
λ
α
Data were collected at 170 K. The structure was solved
by direct methods and successive Fourier difference
syntheses and was refined on F2 by weighted anisotroꢀ
pic fullꢀmatrix leastꢀsquares methods [18]. All nonꢀ
hydrogen atoms were refined anisotropically, while the
hydrogen atoms were calculated and, therefore,
included as isotropic fixed contributors to Fc. Data
collection and data reduction were done with the
CRYSALISꢀCCD and CRYSALISꢀRED programs
[19]. All other calculations were performed with stanꢀ
dard procedures (WINGX) [20]. Crystal data, strucꢀ
Reflections with
I
> 2σ(I)
N
262
v
R
(
F2 > 2
σ(
F2))
0.039
2
wR
(
F
)
0.077
Δρmax/Δρmin
,
e
Å–3
0.83/–0.56
0.77
S
(
Δ
/
σ)
max
0.002
Index parameters
–18
–18
–18
≤
≤
≤
h
k
l
≤
≤
≤
17
11
11
ture refinement and collection parameters for
listed in Table 1.
I are
Fo2) + (0.0275
2
2
w
= 1/[
σ
(
P
) ], where
P
= (Fo2 + 2Fc2)/3.
Supplementary material has been deposited with
the Cambridge Crystallographic Data Centre
(no. 810811; deposit@ccdc.cam.ac.uk or http://www.
ccdc.cam.ac.uk).
back bonding. In the infrared spectra of I the sharp band
in a range of 2048 cm–1 that is absent in the spectrum of the
pure ligand is assignable to the asymmetric stretching vibraꢀ
tion of the N3 moiety [6–11]. The phenolic C–O stretchꢀ
RESULTS AND DISCUSSION
ing is obtained at about 1290 cm–1 in and 1278 cm–1 in the
I
free ligand [21, 22]. The ligand coordination to the cobalt
center is substantiated by prominent bands appeared at
nearly 463 and 418 cm–1, which can be attributed to
H2BrSal2MeРn was prepared by the condensation
of 2,2ꢀdimethylpropylenediamine with 5ꢀbromosaliꢀ
cylaldehyde following the literature methods [17]. The
Schiffꢀbase ligand H2BrSal2MeРn is soluble in comꢀ
mon solvents, such as CHCl3 and CH2Cl2, while the
respective Mn(III) complex is soluble in DMF and
DMSO but insoluble in EtOH, MeOH, CHCl3, and
ν(Co–N) and
ν(Co–O), respectively [21, 22].
The molecular structure of complex
I, including the
CH2Cl2. All compounds synthesized in this work are atomꢀnumbering schemes, is shown in Fig. 1, and selectꢀ
stable at room temperature in the solid state.
ed bond lengths and angles are given in Table 2. Singleꢀ
crystal Xꢀray analyses reveal that complex I consists of
oneꢀdimensional chains based on [Mn(BrSal2MeРn)]+
subunits, and the manganese center has a distorted octaꢀ
hedral geometry, which is coordinated by the N2O2 donor
atoms from one BrSal2MePn ligand in the equatorial
plane and two nitrogen donor atoms from two μ1,3ꢀazido
ions in the axial direction [6–11]. Each azide ligand
function as a trans μ1,3 bridge to link monomeric
The IR spectra of the free ligand H2BrSal2MРn exꢀ
hibit the characteristic band of the imine group (–C=N–)
which appears at 1633 cm–1. This band is shifted in the
complexes toward lower frequencies because of the coorꢀ
dination of the nitrogen atom to the metal ion [6–11],
and appears at 1619 cm–1 (
the –C=N– vibration with an addition coordination to
the Mn atom can be attributed to the metal to ligand
I). The observed red shift of
πꢀ
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 7
2011

520
KHALAJI, TRIKI
C(17)
C(15)
C(18)
Br(2)
N(5)
C(16)
C(19)
O(2)
N(4)
N(3)
O(1)
C(2)
C(14)
C(1)
C(13)
N(2)
C(3)
Mn
N(1)
H(8b)
C(8)
C(7)
C(4)
C(6)
C(10)
C(5)
Br(1)
C(9)
C(12)
C(11)
Fig. 1. Molecular structure of I, showing 50% probability displacement ellipsoids and atom numbering. Dashed lines indicate
…
C⎯H N hydrogen bond.
Fig. 2. View of the oneꢀdimensional zigzag chain of I.
[Mn(BrSal2MeРn)]+ units into a oneꢀdimensional zigꢀ
zag chain along the axis (Fig. 2). The chain structure
belongs to a modification of the type azide chain based
on the recent classification [23].
In the equatorial plane the bond lengths of Mn–N(1),
Mn–N(2), Mn–O(1), and Mn–O(2) are 2.005(3),
2.013(3), 1.892(2), and 1.894(2) , respectively, which
are close to those in other oneꢀdimensional mangaꢀ
Schiffꢀbase complexes and are elongated to the Jаhn–
Teller distortion at the highꢀspin d4 Mn(III) center
[6⎯11]. In complex I, the equatorial atoms Mn, O(1),
O(2), N(1), and N(2) are nearly coplanar and the two
phenyl rings of 5ꢀbromosalicylaldehyde lie in two differꢀ
ent planes.
x
I
The equatorial angles of I are similar to those found in
[Mn(Salpn)(N3)] [7, 8], [Mn(Salen)(N3)] [8], and
Å
nese(III) Schiffꢀbase complexes [6–11]. The bond disꢀ [Mn(XꢀSalen)(N3)] [10, 11]. As for μ1,3ꢀazido anions,
tances in the axial position of Mn–N(3) and Mn–N(5)i the N(3)–N(4) and N(4)–N(5) bond distances have
are 2.266(3) and 2.284(3) Å, respectively, which are close almost the some lengths (1.178(4) and 1.174(4) Å, reꢀ
to those in other oneꢀdimensional manganese(III) spectively), and the N(3)N(4)N(5) bond angle is
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 7
2011

SYNTHESIS AND CRYSTAL STRUCTURE
Table 2. Selected bond distances and angles for
521
I*
Bond
d
, Å
Bond
d, Å
N(1)–Mn
O(1)–Mn
2.005(3)
1.892(2)
1.178(4)
1.479(4)
1.281(4)
1.907(3)
1.327(4)
2.266(3)
N(5)–Mni
N(2)–Mn
2.284(3)
2.013(3)
1.174(4)
1.283(4)
1.473(4)
1.898(4)
1.314(4)
N(3)–N(4)
C(10)–N(2)
C(7)–N(1)
C(4)–Br(1)
C(1)–O(1)
N(3)–Mn
N(5)–N(4)
C13–N(2)
C(8)–N(1)
C(16)–Br(2)
C(19)–O(2)
Angle
ω
, deg
Angle
ω
, deg
N(1)MnN(2)
O(2)MnN(1)
O(2)MnN(2)
C(13)N(2)C(10)
C(8)N(1)Mn
C(10)N(2)Mn
N(4)N(5)Mni
N(1)C(7)C(6)
C(1)O(1)Mn
N(2)C(13)C(14)
O(1)Mn)N(3)
N(1)Mn)N(3)
O(1)MnN(5)ii
N(1)MnN(5)ii
88.17(11)
176.41(11)
89.48(11)
118.8(3)
118.9(2)
115.9(2)
129.1(3)
126.7(3)
125.8(2)
126.3(3)
96.31(11)
85.64(11)
87.23(11)
90.37(12)
177.1(4)
O(1)MnO(2)
O(1)MnN(1)
O(1)MnN(2)
C(7)N(1)C(8)
C(7)N(1)Mn
C(13)N(2)Mn
N(4)N(3)Mn
N(1)C(8)C(9)
C(19)O(2)Mn
N(2)C(10)C(9)
O(2)MnN(3)
N(2)MnN(3)
O(2)MnN(5)ii
N(2)MnN(5)ii
N(3)MnN(5)ii
92.06(10)
90.51(10)
174.86(11)
118.4(3)
122.3(2)
125.1(2)
138.8(3)
115.5(3)
128.9(2)
115.0(3)
91.58(11)
88.55(11)
92.26(11)
87.80(11)
174.68(11)
N(5)N(4)N(3)
i
ii
* Symmetry codes:
x, ⎯y ⎯ 1/2, z + 1/2; x, ⎯y ⎯ 1/2, z ⎯ 1/2.
177.1(4)°, which is close to 180
°
[6–11]. The distancꢀ
, being a little longer
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