Syntheses, structures and magnetic properties of azido- and phenoxo-bridged complexes of manganese containing tridentate aroylhydrazone based ligands

Article abstract of DOI:10.1016/j.poly.2013.05.033

Five new compounds have been prepared by the reaction of MnCl ₂·4H₂O with aroylhydrazone in the presence of NaN₃: [Mn(L¹)(N₃)(HOCH₃)] ₂(1), [Mn(L²)(N₃)(HOCH

Full text of DOI:10.1016/j.poly.2013.05.033

Polyhedron 61 (2013) 45–55
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Syntheses, structures and magnetic properties of azido- and phenoxo-
bridged complexes of manganese containing tridentate aroylhydrazone
based ligands
a
b,
c
c
Hassan Hosseini-Monfared a, , Rahman Bikas , Joaquín Sanchiz , Tadeusz Lis , Milosz Siczek ,
⇑
⇑
Jiri Tucek c, Radek Zboril d, Peter Mayer e
a Department of Chemistry, University of Zanjan, 45195-313 Zanjan, Iran
b Departamento de Química Inorganíca, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
c Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, Wroclaw 50-383, Poland
d Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 1192/12,
in Olomouc, 771 46 Olomouc, Czech Republic
e Fakultat für Chemie und Pharmazie, Ludwig-Maximilians-Universitat, München, Butenandtstr. 5-13, Haus D, D-81377 München, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Five new compounds have been prepared by the reaction of MnCl2ꢀ4H2O with aroylhydrazone in the pres-
ence of NaN3: [Mn(L1)(N3)(HOCH3)]2 (1), [Mn(L2)(N3)(HOCH3)]2 (2), [Mn(L3)(N3)(HOCH3)0.75(EtOH)0.25]2 (3),
[Mn(L4)(N3)(HOCH3)]2 (4) and [Mn2(L2)2(HOCH3)2]n (5). (HL1 = (E)-3-hydroxy-N0-(1-(pyridin-2-yl)ethyli-
Received 14 March 2013
Accepted 19 May 2013
Available online 27 May 2013
dene)-2-naphthohydrazide, HL2 = (E)-N0-(phenyl(pyridin-2-yl)methylene)furan-2-carbohydrazide, H2L3
=
(Z)-N0-(4-oxo-4-phenylbut-2-en-2-yl)isonicotinohydrazide, H2L4 = (E)-N0-(5-bromo-2-hydroxybenzylid-
ene)isonicotinohydrazide). In absence of NaN3 the mononuclear complex [Mn(H2L5)2(EtOH)2Cl2] (6) was
obtained by the reaction of MnCl2ꢀ4H2O and H2L5 ((E)-N0-(2-hydroxy-3-methoxybenzylidene)ison-
icotinohydrazide). All the compounds have been characterized by elemental analyses, IR spectra, single
crystal X-ray diffraction and magnetic susceptibility measurements. Compound 6 exhibits mononuclear
structure, 1–4 dinuclear structure whereas complex 5 yields two-dimensional sheets parallel to the
(100) plane in which the deprotonated H2L4 act as bridging ligand. The magnetic study reveals dominating
antiferromagnetic interactions in 1 and 5 whereas the ferromagnetic coupling dominates in 2–4. The mag-
netic properties are interpreted in terms of the electronic structure of the Mn ions and structural
parameters.
Keywords:
Dinuclear Mn complexes
Magnetic behavior
Azide
Coordination polymer
Hydrazones
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
behavior. Due to the presence of energy barrier between spin-up
and spin-down states, the SMMs may be potentially used as infor-
The study of poly-nuclear manganese complexes is of current
interest due to the role they play in several redox systems such
as in water oxidation in the active centre of Photosystem II [1]
and in other redox-biochemical processes. Additionally, many
manganese complexes possess large numbers of unpaired elec-
trons, making them precursors for magnetic materials [2–5]. These
findings have triggered the investigation of new molecular com-
plexes based on manganese ions. In this context, dinuclear manga-
nese Schiff base complexes are known to exhibit interesting
magnetic properties [6,7] that can further be tailored towards
assembly of molecule exhibiting single molecule magnet (SMM)
mation storage at the molecular level. Moreover, these might be
the unique systems for studying quantum spin tunnelling and
quantum phase interference leading to their applications in molec-
ular electronics too [8].
Among the bridging pseudohalide ions (N3ꢁ, NCSꢁ, NCOꢁ), the
azide has been widely utilized not only as a versatile bridging li-
gand, but also as an excellent magnetic coupler [9]. When the azide
anion acts as bridging ligand [10], it can bind metal ions in differ-
ent coordination modes. The most common are the end-to-end
(
l
2-1,3-N3, EE) [11], and end-on (
whereas triply 3-1,1,1-N3 [13],
4-1,1,1,1-N3 [10] and 4-1,1,3,3-N3 [15] coordinated modes re-
main relatively rare (Scheme 1). In most cases the end-to-end
1,3) and end-on ( 1,1) coordination modes mediate antiferromag-
l
2-1,1-N3, EO) [12] modes,
l
l3-1,1,3-N3 [14] quadruply
l
l
⇑
Corresponding authors. Tel.: +98 241 5152576; fax: +98 241 5283203 (H.
Hosseini-Monfared).
(l
l
netic and ferromagnetic interaction, respectively, but an increasing
number of exceptions have been recently observed [16]. Hence, the
E-mail addresses: monfared@znu.ac.ir (H. Hosseini-Monfared), jsanchiz@ull.es (J.
Sanchiz), milosz.siczek@chem.uni.wroc.pl (M. Siczek), radek.zboril@upol.cz (R.
Zboril), pemay@cup.uni-muenchen.de (P. Mayer).
0277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2013.05.033

46
H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
of azide and hydrazone Schiff base as ligands could be interesting. In
this sense, there are only a few studies on azide as bridging [29] and
non-bridging ligands between two Mn(III) ions [30,31]. And to the
best of our knowledge, there is no report on the structure of Mn(II)
hydrazone complexes with azide bridging ligands. Thus in order to
improve the knowledge in this kind of compounds we report herein
the structures, thermal stability and magnetic properties of mono-
nuclear, dinuclear and polymeric Mn(II,III) complexes with mixed
azide and aroyl hydrazone ligands (Scheme 2).
Scheme 1. The common metal ion bridging modes for azide ion illustrated by
double-bridged l2-1,3 (EE), l2-1,1 (end-on), triple-bridged l3-1,1,3 and l3-1,1,1.
synthesis, the structural characterization and the study of the
magnetic properties of azide-containing complexes with different
magnetic features is an emerging and substantial subject of scien-
tific researches.
2. Experimental
2.1. Materials and instrumentations
Acyl and aroyl hydrazones are a multipurpose class of ligands
(Scheme 2) which have a range of biological and chemical activi-
ties. Hydrazones exhibit physiological and biological activities in
the treatment of several diseases such as tuberculosis [17], Fe over-
load [18,19], and also as inhibitors for many enzymes [20]. Their
metal complexes have also found applications in various physical
and chemical processes e.g. non-linear optics, sensors, medicine
[21] and, as well as non-symmetrical salens, can act as effective
catalysts towards alkene epoxidation [22]. Moreover, they are of
interest in the field of electrochromism where a change in the oxi-
dation state of the metal is possible [23]. Acyl and aroyl hydra-
zones contain trigonal N- and O-donor atoms that can coordinate
to metal ions [24] acting as bidentate [25], tridentate, tetradentate
[26], or pentadentate ligands [27] depending on the nature of het-
erocyclic ring-substituents attached to the hydrazone unit. These
ligands exhibit a facile keto–enol tautomerization which can
modulate the coordination to the metal as a mono-negative or
di-negative ligand in the keto or enol form, respectively.
Manganese(II) chloride tetrahydrate, sodium azide, 4-pyridine-
carboxylic acid hydrazide, furane-2-carboxylic acid hydrazide,
3-hydroxy-2-naphthoic acid hydrazide, 5-bromo-2-hydroxybenz-
aldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-acethylpyridine,
2-benzoyilpyridine, benzoylacetone and solvents were purchased
from Merck and used as received. IR spectra were recorded in
KBr disks with a Bruker FT-IR spectrophotometer. UV–Vis spectra
of solutions were recorded on a thermo spectronic, Helios Alpha
spectrometer. Elemental analyses were determined on a CHN Per-
kin–Elmer 2400 analyzer. The manganese content of the final
material was determined by a Varian spectrometer AAS-110.
2.2. Synthesis of the ligands
General procedure: the ligands were prepared in a similar man-
ner by refluxing a mixture of acid hydrazide (1.0 mmol) and appro-
priate aldehyde or ketone with equivalent molar ratio in 20 ml
methanol for 6 h. The solution volume was decreased to 5 ml by
removing the solvent and cooled to room temperature. The
Metal complexes with mixed ligands of hydrazone Schiff base
and azide are rare [28], although combination of different properties
Scheme 2. The aroylhydrazone ligands which used in the synthesis of complexes.

H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
47
obtained solids were separated and filtered off, washed with
cooled methanol and then dried in air. Completion of the reactions
was checked by TLC on silica gel plates.
2.2.5. (E)-N0-(2-hydroxy-3-methoxybenzylidene)isonicotinohydrazide
(H2L5)
Yield: 90%. Color: white. M.p. 262 °C. Anal. Calc. for C14H13N3O3
(MW = 271.27 g/mol): C, 61.99; H, 4.83; N, 15.49. Found: C, 61.90;
H, 4.79; N, 15.54%. 1H NMR (250.13 MHz, DMSO-d6, 25 °C, TMS): dH
12.25 (s, 1H, CO–NH–), 10.69 (s, 1H, -OH), 8.77 (d, 2H, J = 2.25 Hz),
8.67 (s, 1H, –CH@N), 7.81 (d, 2H, J = 2.25 Hz), 7.17 (d, 1H,
J = 7.5 Hz), 7.02 (d, 1H, J = 7.5 Hz), 6.84 (t, 1H, J = 7.75 Hz), 3.79 (s,
3H, –OCH3) ppm. 1H NMR (250.13 MHz, DMSO-d6 + D2O): dH 8.58
(s, 1H, –CH@N), 6.83–8.70 (7H, aromatics), 3.74 (3H, OCH3) ppm.
13C NMR (62.90 MHz; DMSO-d6): dC 56.3, 114.4, 119.4, 119.6,
120.9, 122.1, 140.4, 147.6, 148.4, 149.3, 150.9, 161.8. UV–Vis in
2.2.1. (E)-3-Hydroxy-N0-(1-(pyridin-2-yl)ethylidene)-2-
naphthohydrazide (HL1)
Yield: 87%. Color: light brown. M.p. >200 °C. Anal. Calc. for
C18H15N3O2 (MW = 305.33 g/mol): C, 70.81; H, 4.95; N, 13.76.
Found: C, 70.62; H, 4.87; N, 13.80%. 1H NMR (250.13 MHz,
DMSO-d6, 25 °C, TMS): dH 11.79 (s, 1H, N–H), 11.66 (s, 1H, O–H),
8.64 (s, 1H), 8.15 (d, 1H, J = 8.00 Hz), 7.99 (d, 1H, J = 7.75 Hz),
7.88 (t, 1H, J = 7.5 Hz), 7.76 (d, 1H, J = 8.25 Hz), 7.50 (m, 4H), 7.34
(d, 1H, J = 8.00 Hz), 2.42 (s, 3H). 1H NMR (250.13 MHz, DMSO-
d6 + D2O): dH 7.18–8.77 (10H- Aromatics), 2.60 (s, 3H) ppm. 13C
NMR (62.90 MHz, DMSO-d6): dC 12.3, 111.2, 120.9, 121.1, 124.4,
124.7, 126.2, 127.7, 128.8, 129.4, 133.0, 136.3, 137.2, 149.1,
CH3OH [kmax/nm, with
e
(dm3 molꢁ1 cmꢁ1)]: 223 (23 940), 305
(20 020).
2.3. Synthesis of the complexes
154.0, 153.0, 155.3, 162.0. UV–Vis in CH3OH [kmax/nm, with
e
(dm3 molꢁ1 cmꢁ1)]: 228 (101000), 311 (73900), 366 (22300sh).
IR data of the ligands and complexes are given in Supplementary
Information.
Polycrystalline samples of the 1–4 complexes were obtained by
the same method. The desired ligand (HL1, HL2, H2L3 and H2L4)
(0.196 mmol) was dissolved in a mixed-solvent solution (metha-
nol/ethanol 70:30 v/v, 30 ml) and to this solution MnCl2ꢀ4H2O
(78 mg, 0.392 mmol) and NaN3 (4 mg, 0.615 mmol) were added
and then gently refluxed for 4 h. After cooling, the resulting solid
was filtered off, washed with cooled absolute ethanol and dried
at 100 °C. (Caution! Azido compounds of metal ions are potentially
explosive and only a small amount of the materials should be pre-
pared and handled with care).
2.2.2. (E)-N0-(phenyl(pyridin-2-yl)methylene)furan-2-carbohydrazide
(HL2)
Yield: 92%. Color: light brown. M.p. 122 °C. Anal. Calc. for
C17H13N3O2 (MW = 291.30 g/mol): C, 70.09; H, 4.50; N, 14.42.
Found: C, 70.14; H, 4.45; N, 14.53%. 1H NMR (250.13 MHz,
DMSO-d6, 25 °C, TMS): dH 14.67 (s, 1H, CO–NH–), 9.73 (s, 1H),
8.92 (s, 1H), 8.10 (d, 1H, J = 6.75 Hz), 7.94 (m, 2H), 7.30–7.54 (m,
5H), 6.70 (d, 1H, J = 7.25 Hz) ppm. 13C NMR (62.90 MHz; DMSO-
d6): dC 112.9, 122.0, 124.6, 125.5, 126.7, 128.9, 129.3, 129.5,
131.7, 137.2, 137.8, 138.8, 146.7, 149.0, 149.3, 152.1, 155.3 ppm.
Single crystals of the complexes were obtained by the reaction
of MnCl2ꢀ4H2O (95 mg, 0.48 mmol), NaN3 (47 mg, 0.723 mmol) and
0.24 mmol of the desired ligand which were placed in the main
arm of a branched tube and a mixed solvent solution of metha-
nol/ethanol (70:30 v/v) was added to fill the arms. The tube was
sealed and the arm containing the reagents immersed in an oil
bath at 60 °C while the other arm was kept at ambient tempera-
ture. After 5 days, crystals of 1–5 were deposited in the cooler
arm, which were analyzed after separation and washing with
methanol. The red complex [Mn2(L4)2(HOCH3)2]n (5) was produced
as minor product in the synthesis of complex 4.
UV–Vis in CH3OH [kmax/nm, with
e
(dm3 molꢁ1 cmꢁ1)]: 205
(40600sh), 272 (19260), 315 (25800).
2.2.3. (E)-N0-((Z)-4-hydroxy-4-phenylbut-3-en-2-
ylidene)isonicotinohydrazide (H2L3)
Yield: 89%. Color: colorless. M.p. 159 °C. Anal. Calc. for
Compound 6 is obtained by refluxing H2L5 (0.05, 0.178 mmol)
and MnCl2ꢀ4H2O (70 mg, 0.355 mmol) in 10 ml ethanol for 4 h.
Then filtered and washed with ethanol.
C16H15N3O2 (MW = 281.31 g/mol): C, 68.31; H, 5.37; N, 14.94.
Found: C, 68.48; H, 5.32; N, 15.02%. 1H NMR (250.13 MHz,
DMSO-d6, 25 °C, TMS): dH 12.28 (s, 1H), 11.14 (s, 1H), 8.77 (d, 2H,
J = 4.75 Hz), 8.65 (s, 1H), 7.88 (d, 2H, J = 6.25 Hz), 7.78 (d, 2H,
J = 7.25 Hz), 7.45 (m, 3H), 5.99 (s, 1H), 2.07 (s, 3H) ppm. 1H NMR
(250.13 MHz, DMSO-d6 + D2O): dH 7.72–8.72 (9H, aromatic), 5.95
(s, 1H), 2.03 (s, 3H) ppm. 13C NMR (62.90 MHz; DMSO-d6): dC
16.1 (CH3 of the first tautomer), 18.4 (CH3 of the second tautomer),
92.3, 93.3, 121.9, 123.0, 125.0, 127.4, 127.7, 128.5, 128.8, 131.6,
139.3, 139.9, 143.5, 143.9, 150.0, 150.9, 156.3, 164.0, 164.7, 165.2
(Ph–C(OH)@, the second tautomer), 186.7 (the carbonyl of benzoyl,
Ph–C(O)–, the first tautomer) ppm. UV–Vis in CH3OH [kmax/nm,
2.3.1. [Mn(L1)(N3)(OHCH3)]2 (1)
Yield: 73%. Color: red–orange. Anal. Calc. for C38H36Mn2N12O6
(MW = 866.67) C, 52.66; H, 4.19; N, 19.39; Mn, 12.68. Found: C,
52.70; H, 4.16; N, 19.46; Mn, 12.50%. UV–Vis in CH3OH [kmax/nm,
with
e
(dm3 molꢁ1 cmꢁ1)]: 207 (93750), 230 (72900), 362 nm
(47000).
2.3.2. [Mn(L2)(N3)(HOCH3)]2ꢀ0.5(CH4O) (2)
with
e
(dm3 molꢁ1 cmꢁ1)]: 211 (25920), 249 (16780), 335
Yield: 79%. Color: red–orange. Anal. Calc. for C36H32Mn2N12O6
(MW = 854.64 g/mol): C, 51.30; H, 4.01; N, 19.67; Mn, 12.86.
Found: C, 51.44; H, 3.96; N, 19.82; Mn, 12.97%. UV–Vis in CH3OH
(10500), 403 (8640).
2.2.4. (E)-N0-(5-bromo-2-hydroxybenzylidene)isonicotinohydrazide
(H2L4)
[kmax/nm, with
e
(dm3 molꢁ1 cmꢁ1)]: 205 (94100), 261 (46450),
290 (40050sh), 385 (86000).
Yield: 94%. Color: white. M.p. 286 °C. Anal. Calc. for C13H10BrN3-
O2 (MW = 320.14 g/mol): C, 48.77; H, 3.15; N, 13.13. Found: C,
48.70; H, 3.17; N, 13.09%. 1H NMR (250.13 MHz, DMSO-d6, 25 °C,
TMS): dH 12.34 (s, 1H, CO–NH–), 11.13 (s, 1H, –OH), 8.76 (d, 2H,
J = 4.25 Hz), 8.61 (s, 1H, –CH@N), 7.80 (m, 3H), 7.39 (d, 1H,
J = 8.5 Hz), 6.87 (d, 1H, J = 8.5 Hz) ppm. 1H NMR (250.13 MHz,
DMSO-d6 + D2O): dH 8.56 (s, 1H, CH@N), 8.72 (7H, aromatics)
ppm. 13C NMR (62.90 MHz; DMSO-d6): dC 111.0, 119.1, 121.7,
130.6, 134.3, 140.3, 146.9, 150.0, 153.9, 156.9, 162.0 ppm. UV–Vis
2.3.3. [Mn(L3)(N3)(HOCH3)0.75(EtOH)0.25 2
] (3)
Yield: 76%. Color: black. Anal. Calc. for C34.50H35Mn2N12O6
(MW = 823.62 g/mol): C, 50.31; H, 4.28; N, 20.41; Mn, 13.34.
Found: C, 49.98; H, 4.23; N, 20.55; Mn, 14.00%. UV–Vis in CH3OH
[kmax/nm, with
e
(dm3 molꢁ1 cmꢁ1)]: 231 (58150), 270 (44400),
336 (26800), 431 (29450).
2.3.4. [Mn(L4)(N3)(OHCH3)]2 (4)
Yield: 83%. Color: black. Anal. Calc. for C28H24Br2Mn2N12O6
(MW = 894.25) C, 37.61; H, 2.71; N, 18.80, Mn, 12.29. Found: C,
in CH3OH [kmax/nm, with
e
(dm3 molꢁ1 cmꢁ1)]: 220 (29500), 246
(15780sh), 290 (19800), 342 (14160).

48
H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
37.69; H, 2.70; N, 18.89; Mn, 12.15%. UV–Vis in CH3OH [kmax/nm,
with
(dm3 molꢁ1 cmꢁ1)]: 236 (89800), 316 (48900), 417 nm
structure plots were prepared with DIAMOND [34]. The crystal data
and refinement parameters are presented in Table 1.
e
(24850).
2.5. Magnetic measurement
2.3.5. [Mn2(L4)2(OHCH3)2]n (5)
Yield: 72%. Color: red–orange. Anal. Calc. for C28H24Br2Mn2N6O6
(MW = 810.21 g/mol): C, 41.51; H, 2.99; N, 10.37; Mn, 13.56.
Found: C, 41.35; H, 3.02; N, 10.31; Mn, 13.45%. UV–Vis in CH3OH
[kmax/nm, with
324 (28750), 406 (14600).
Magnetic susceptibility measurements on polycrystalline sam-
ples were carried out by means of a Quantum Design SQUID MPMS
XL magnetometer. The dc measurements were performed in the
temperature range 1.9–300 K at applied magnetic fields of
1000 Oe. ac measurements were performed in the 2–5 K range un-
der a dc field of 0 Oe and an ac field of 3.5 Oe. Diamagnetic correc-
tions of the constituent atoms were estimated from Pascal’s
constants [2] and experimental susceptibilities were also corrected
for the temperature-independent paramagnetism and the magne-
tization of the sample holder.
e
(dm3 molꢁ1 cmꢁ1)]: 227 (66500), 268 (41950sh),
2.3.6. [Mn(H2L5)2(OHCH2CH3)Cl2] (6)
Yield: 78%. Color: yellow. Anal. Calc. for C32H38Cl2MnN6O8
(MW = 760.52 g/mol): C, 50.54; H, 5.04; N, 11.05; Mn, 7.22. Found:
C, 50.40; H, 5.09; N, 11.13; Mn, 7.30%. UV–Vis in CH3OH [kmax/nm,
with e
(dm3 molꢁ1 cmꢁ1)]: 224 (75050), 307 (44650), 405 (12500).
3. Results and discussion
2.4. X-ray diffraction data collection and refinement
3.1. Syntheses of complexes and spectroscopy
Data collections for X-ray structure determination were per-
formed on a KUMA KM4 CCD (1) and an Oxford Diffraction XCali-
The ligands were prepared in methanol following the reported
method [22]. The reaction of aromatic acid hydrazides with fa-
vored aldehyde/ketones containing N/O donor atom in suitable po-
sition gave the desired tridentate Schiff base ligands in excellent
yields and purity which are shown in Scheme 2. The analytical
and spectroscopic data confirmed the syntheses of the ligands.
1H NMR, 13C NMR and IR spectroscopy confirmed that aroylhydraz-
one moiety of the ligands are in keto-form in solution and solid
state. Furthermore, the 13C NMR spectrum of ligand H2L3 proved
the existence of two tautomeric forms which are in equilibrium
bur (2, 3, 4, 5, 6) using Mo K
a radiation (0.71073 Å) at low
temperatures. The structures were solved by direct methods with
SHELXS [32] or SIR97 [33], and refined with full-matrix least-squares
technique on F2 with SHELXL-97 [32]. The hydrogen atoms were cal-
culated in idealized geometry riding on their parent atoms with
the exception of the methanol-O-bonded hydrogen (located from
difference maps). The disorder of the methanol molecule in 2 has
been refined by a split model. The O-bonded hydrogen atoms were
located from the difference maps and refined with constraints. The
Table 1
Parameters of data collection and structure refinement of 1-6.
1
2
3
4
5
6
Net formula
C
38H36Mn2N12O6
C36H32Mn2N12O6ꢀ0.5(CH4O) C34.50H35
C28H24Br2Mn2N12O6 C28H24Br2Mn2N6O6 C32H38Cl2MnN6O8
Mn2N12O6
Mr (g molꢁ1
Crystal size (mm)
T (K)
)
866.67
854.64
823.62
894.252
810.211
0.15 ꢂ 0.13 ꢂ 0.12
173(2)
760.52
0.26 ꢂ 0.20 ꢂ 0.18 0.22 ꢂ 0.15 ꢂ 0.11
0.46 ꢂ 0.32 ꢂ 0.26 0.19 ꢂ 0.12 ꢂ 0.03
0.20 ꢂ 0.17 ꢂ 0.10
100 (2)
90 (2)
100 (2)
100(2)
100
Diffractometer
Crystal system
Space group
a (Å)
b (Å)
c (Å)
KUMA KM4 CCD
monoclinic
P21/c
11.451 (4)
7.851 (2)
22.101 (7)
Xcalibur PX
triclinic
P1
Xcalibur PX
monoclinic
P21/n
9.955 (3)
17.603 (6)
11.531 (4)
‘OxfordXCalibur’
‘OxfordXCalibur’
monoclinic
C2/c
16.3851 (10)
13.6703 (5)
17.7092 (15)
90
129.237 (4)
90
3072.3 (3)
4
Oxford Xcalibur
triclinic
P1
triclinic
ꢀ
ꢀ
ꢀ
P1
9.736 (4)
12.988 (5)
17.104 (7)
73.08 (4)
75.49 (4)
70.89 (5)
1926.1 (13)
2
7.9733 (5)
10.0811 (7)
10.5840 (5)
98.814 (5)
98.786 (5)
93.320 (5)
827.94 (9)
1
8.222 (3)
8.918 (3)
12.458 (4)
69.33 (5)
89.78 (5)
74.71 (5)
820.4 (5)
1
a
(°)
b (°)
101.66 (3)
114.10 (5)
c
(°)
V (Å3)
1945.9 (10)
2
1.479
1844.5 (13)
2
1.483
Z
Calc. density (g cmꢁ3
)
1.474
0.72
1.79356(19)
3.238
1.75166(17)
3.475
1.539
0.63
l
(mmꢁ1
)
0.71
0.75
Absorption correction
Transmission factor range
Refls. measured
Rint
analytical
0.866, 0.912
31102
0.034
analytical
0.878, 0.925
22371
0.028
analytical
0.762, 0.839
14776
0.019
‘multi-scan’
0.86623–1.00000
6278
‘multi-scan’
0.92214–1.00000
11836
analytical
0.873–0.944
14463
0.045
0.0392
0.0416
h range
Observed refls.
2.8–36.9
6109
2.4–35
8815
2.5–29
4005
4.14–26.33
1936
4.21–26.35
1983
2.5–34.1
4549
X, y (weighting scheme)
Hydrogen refinement
Reflections in refinement
Parameters
0.039, 0
geom.
9119
0.052, 0
geom
12848
557
0.043, 0.273
geom
4670
0.0195, 0
mixed
3354
0.0349, 0
mixed
3121
0.064, 0
geom
6662
265
257
231
204
225
Restraints
0
0
2
1
0
0
R(Fobs
)
0.037
0.081
0.041
0.104
0.026
0.074
0.0372
0.0629
0.0323
0.0713
0.046
0.119
Rw(F2)
S
1.01
1.02
1.09
0.788
0.876
1.01
Shift/errormax
0.002
0.001
0.001
0.001
0.001
0.001
Max/min electron density
0.54/ꢁ0.26
0.97/ꢁ0.31
0.37/ꢁ0.27
0.805/ꢁ0.379
0.808/ꢁ0.442
1.12/ꢁ1.15
(e Åꢁ3
)

H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
49
in the solution; it shows 23 resonances, while the ligand contains
only 16 carbon atoms (see Section 2).
of an intramolecular hydrogen bond between O–H from naphthyl
ring and of amide group nitrogen in enol form. The disappearance
of the bands at 1266 cmꢁ1 (H2L4) in complexes 4 and 5 show the
involvement of phenolic oxygen in coordination through deproto-
nation. In complex 6 the stretching bands related to functional
groups O–H, N–H, C@O and C@N are almost the same with that
of H2L5 (Table 2) hence the hydrazone ligand H2L5 coordinate as
a neutral monodentate ligand. Additionally, the appearance of very
broad band at around 3400 cmꢁ1 can be related to the coordinated
methanol (in 1–5) or ethanol (in 3, 6) to the manganese center
[42,43].
One-pot synthesis of 1:2:3 molar ratio of aroylhydrazone (HL1,
HL2, H2L3, H2L4), manganese(II) chloride tetrahydrate and NaN3 in
methanol/ethanol (70:30 v/v) afforded hexacoordinated dinuclear
compounds of [Mn(L1)(N3)(HOCH3)]2 (1), [Mn(L2)(N3)(HOCH3)]2
(2), [Mn(HL3)(N3)(HOCH3)0.75(EtOH)0.25 2 (3) and [Mn(L4)(N3)(-
]
HOCH3)]2 (4), respectively. All complexes have been isolated in
good yield and micro analytical data are consistent with the com-
positions proposed. The products in cases 3 and 4 contain manga-
nese(III) rather than manganese(II), as in the starting materials,
due to aerial oxidation that occurs spontaneously in the reaction
mixture. Other workers have reported similar observations
[35,36]. The coordination polymer [Mn2(L4)2(HOCH3)2]n (5) was
produced as the minor product in the synthesis of complex 4. How-
ever, the reaction of H2L4, MnCl2ꢀ4H2O and NaN3 with molar ratios
of 1:2:0.4 in methanol/ethanol produced merely compound 5. The
presence of sodium azide to synthesis compound 5 is essential; in
the absence of NaN3, the solution of H2L4 and MnCl2ꢀ4H2O at 60 °C
remained without any change even after one month, but after the
addition of NaN3 the solution color changed and 5 was formed
immediately. Ligand H2L5 was treated with MnCl2ꢀ4H2O in the ab-
sence of NaN3 with expectation to get a coordination polymer sim-
ilar to 5, but the mononuclear Mn(II) complex 6 was produced in
which two H2L5 without deprotonation and two ethanol molecules
are coordinated to the Mn centre in addition to the two chloride li-
gands. Moreover, replacing Mn(NO3)2ꢀ4H2O by MnCl2ꢀ4H2O in the
reaction with a similar ligand (isonicotinoylhydrazone) produced
the nitrated ligand without any complex formation [37]]. The typ-
ical syntheses of 1–6 are summarized in Scheme 3.
In methanol solutions, HL1, HL2, H2L3 and H2L4 show absorption
maxima in the region 205–238 nm and 249–403 nm (Table S1).
Based on their extinction coefficients these are assigned as due
to
p ?
p⁄ and n ? p⁄ transitions, respectively. The corresponding
Mn(II) and Mn(III) compounds 1–4 exhibit bands at kmax values
in the region 230–236 nm and 261–417 nm which are assignable
to ligand-based
p ?
p⁄ and n ? p⁄ transitions, respectively. All
bands shifts in complexes indicate the coordination of ligands to
the metal ions. The bands appeared at about 405 nm for complexes
5/6 correspond to MLCT band which is absent in the ligands H2L4
and H2L5.
3.2. Thermal analyses
To examine thermal stabilities of 1, 3 and 5, thermogravimetric
and differential thermal analyses (TG–DTA) were made between
30 and 700 °C in the static atmosphere of nitrogen. TG curve
(Fig. S7) shows that 1 is stable up to 129 °C, where the CH3OH mol-
ecule is removed (observed 7.8, calcd. 7.5%) between 130 and
ꢁ
The compounds were characterized using microanalyses, spec-
troscopic and thermal studies. The microanalytical results are in
good agreement with formulations 1–6. The air-stable compounds
are soluble in a wide range of common organic solvents such as
methanol, acetonitrile, dimethyformamide, dimethylsulfoxide,
but are insoluble in water. Selected stretching frequencies of the li-
gands and their complexes are summarized in Table 2. In IR spec-
tra, the stretching vibrations of azide ion in 1–4 are seen as strong
163 °C, then at 220 °C the N3 is removed (observed 10.6, calcd.
10.5%). At 410 °C the remaining organic aroylhydrazone ligand is
lost (observed 35.4, calcd. 36.3%). TG curve of 3 (Fig. S8) shows that
it losts CH3OH at 144 °C (observed 6.5%, calcd. 7.6%), then at 232 °C
the azide is lost (observed 10.5%, calcd. 11.4%). Finally aroylhydraz-
one L3 is removed during two steps at 341 and 407 °C (observed
30.0%, calcd. 31.7%). A first TG step of complex 5 (Fig. S9) derives
from the methanol loss of the sample at 118 °C (observed 4.8%,
calcd. 7.9%). The remaining organic ligand L4 is removed during
m
as(N3) absorptions at about 2065 cmꢁ1. The peaks above approxi-
mately 2055 cmꢁ1 indicate
l1,1 bridging mode of azides [38]. In the
two steps (at 372 °C,
which results to total mass loss of CH3OH (calcd. 7.9%) + L4 (calcd.
57.9%) to yield the overall mass loss of
D
m ꢃ ꢁ1.7% and at 423 °C,
D
m ꢃ ꢁ29.3%)
IR spectra, the hydrazone ligands show stretching bands attributed
to N–H, C@O and C@N in the range 3134–3263, 1645–1690 and
1552–1603 cmꢁ1, respectively (Table 2) [26,39]. The presence of
D
m ꢃ ꢁ65.3% (calcd. 65.8%)
up to 840 °C. For the studied complexes, the final product is esti-
m
(OH) in HL1 and H2L3–5 as a weak band at about 3400 cmꢁ1 sug-
mated to be Mn2O3.
gests an intramolecular hydrogen bonding (O–Hꢀ ꢀ ꢀN) in these li-
gands [40]. The band at about 1250 cmꢁ1 is attributed to
m(C–O)
3.3. Crystal structures of [Mn(L1)(N3)(HOCH3)]2 (1) and
[Mn(L2)(N3)(HOCH3)]2 (2)
(phenolic) stretching in the ligands H2L5 and H2L6 [41]. On com-
plexation the absence of N–H and carbonyl bands, shifts in azome-
thine (–C@N–) band and appearance of >C@N–N@C< band support
the coordination of the hydrazone ligands in the enol form as
monoanionic {(L1)ꢁ, (L2)ꢁ} in complexes 1 and 2 and dianionic
{(L3)2ꢁ, (L4)2ꢁ} in complexes 3–5 (Scheme 3). Appearance of a
broad peak at 3227 cmꢁ1 in 1 can be ascribed to the persistence
The structural analyses reveal that 1–4 comprise of dinuclear
units containing double
l1,1-N3 bridges, whereas 5 forms a 2D
coordination polymer and 6 is a mononuclear Mn(II) complex.
Selected bond distances and angles are listed in Table S2 of the
Supplementary information section. The structures of 1–4 are built
Scheme 3. Reactions of the aroylhydrazone Schiff base ligands (Scheme 2) and MnCl2ꢀ4H2O with NaN3 to give (b) compounds 1–6.

50
H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
Table 2
Selected characteristic IR bands of the ligands (HL1-2, H2L3-5) and complexes1–6.
Comp.
m(O–H)
N(N–H)
m
(C@O)
m(C@N)
m(N3)
HL1
HL2
H2L3
H2L4
H2L5
1
3445 (w, br)
–
3472 (w, br)
3417 (w, br)
3445 (w, br)
3381 (w)
3263 (m)
3140 (m)
3134 (m)
3141 (m)
3202 (m)
1645 (vs) 1552 (s)
1683 (vs) 1585 (vs)
1689 (vs) 1593 (m)
1675 (vs) 1615 (m)
1690 (vs) 1602 (s)
3227 (m,br) 1630 (m) 1595 (m) 2066 (vs)
2
3
4
5
3597 (w) 3384 (w, br)
3761 (w) 3451 (w,vbr)
3382 (w, br)
3431 (m, vbr)
3458 (s)
–
–
–
–
–
–
–
–
1582 (m) 2065 (vs)
1636 (w) 2069 (vs)
1594 (s) 2063 (vs)
1602 (vs)
6
3199 (m)
1677 (vs) 1609 (m)
up of neutral dinuclear units. In 1 and 2 the two manganese(II)
centres are bridged by two 1,1-N3 to form a planar four membered
Mn–( 1,1-N3)2–Mn ring. The overall geometry around each manga-
Fig. 2. Molecular structure of [Mn(L2)(N3)(HOCH3)]2 (2A); symmetry transforma-
tion i = 2 ꢁ x, 2 ꢁ y, ꢁz.
l
l
nese(II) in complexes 1 and 2 is best described as a distorted octa-
hedron with an MnN4O2 chromophores (Figs. 1 and 2). Compound
2 exhibits two crystallographically independent molecules (de-
scribed as 2A and 2B). Overlay of this two molecules show that
they are almost identical (Fig. S10), and in the following descrip-
tion only molecule 2A will be discussed. The aroylhydrazone Schiff
base ligand forms a basal plane (equatorial plane) together with
the nitrogen atom from the azide bridging ligand. An axial position
is occupied by the oxygen atom from methanol and another axial
position is occupied by the nitrogen atom from the second azide
bridging ligand. In both the cases, each manganese(II) center devi-
ates 0.104(1) Å in 1 and 0.125(1) Å in 2A from the mean plane N1/
N2/O1/N4 towards the methanol. Mn–N bond distances are in the
range 2.1506(11)–2.3109(10) Å for 1 and 2.170(2)–2.3146(18) Å
for 2A. The Mn–O and Mn–N distances are close to those found
in other octahedral Mn(II) complexes with N2O-donor hydrazone
ligand [22,44]. The axial Mn–N4i (i = 1 ꢁ x, 1 ꢁ y, 1 ꢁ z) bond of
2.3109(10) Å is longer than equatorial azide Mn–N4 distance of
2.1506(11) Å. This is thus an example of an asymmetric EO doubly
bridged Mn-azide. The degrees of distortion from ideal octahedral
geometry are reflected in cisoid [71.32(4)–118.83(4)° in 1 and
70.54(7)–113.97(7)° in 2A] and transoid [143.67(4)–173.32(3)° in
1 and 141.97(6)–170.75(5)° in 2A] bond angles; the N4–Mn–N4i
(in 1) and N4A–Mn1–N4Ai (in 2A) bridging angles are 81.69(4)°
and 78.80(7)°, respectively.
very close to those observed in other reported azide bridged man-
ganese complexes [45]. In Mn–(l1,1-N3)2–Mn linkage, the end-on
azide group (N4–N5 bond) is not coplanar with the four-membered
Mn2N2 cyclic unit and makes an angle of 27.01(6)° in 1 and
24.36(12)° in 2A. The end-on azido bridges show asymmetric N–
N distances (N4–N5/N5–N6) of 1.2088(12)/1.1548(13) Å and the
N4–N5–N6 angle is 177.62(12)° in 1 which is in usual manner
for azide ligand [46].
It is worth mention that there is a strong intramolecular O–
Hꢀ ꢀ ꢀN hydrogen bond in complex 1 which effects on the keto–enol
tautomerism (Table 2). Comparing the orientation of the hydrogen
of the naphthol group (O–H) in free ligand with coordinated ligand
to metal ions, indicates that the hydrogen of the hydroxy group in
naphthol orients towards the outside of molecule in free ligands
and takes part in intermolecular hydrogen bonding [47,48],
whereas this hydrogen prefers inside orientation and participates
in intramolecular hydrogen bonding in complex. This hydrogen
bond prevents the tautomerism. N3–C11 and C11–O1 bond lengths
in the naphthohydrazide are 1.3468(14) and 1.2701(13) Å, respec-
tively, and are comparable to similar bond lengths in other re-
ported hydrazone complexes which are about 1.31 and 1.30 Å for
coordinated ligand in enol form [49] while in coordinated ligands
in keto form are about 1.35 and 1.25 Å [22,44]. These finding to-
gether with the IR spectrum (slight decrease in m(C@O)) show that
the hydrogen atom of –NH–C@O has eliminated during the com-
plexation and ligand coordinated in keto form.
In this dimeric unit the Mnꢀ ꢀ ꢀMn distance within the four-
membered Mn2N2 cyclic units is 3.3766(11) Å in
1 and
Adjacent molecules of 1 are connected together by O–Hꢀ ꢀ ꢀO
hydrogen bonding which leads to infinite hydrogen-bonded 1D
chains (Fig. S11, Table S4). Similar motifs can be also found in
the structure 2 where 2A and 2B molecules create separately infi-
nite hydrogen-bonded 1D chains. The molecules of solvated meth-
anol are hydrogen bonded to chains of 2B.
3.4410(15) Å in 2A. The four-membered Mn2(
are planar, as is usual for the double end-on bridges [45]]. The
azide–Mn–N0azide and Mn–Nazide–Mn0 bond angles are respectively
l1,1-N3)2 cyclic units
N
81.69(4)°/98.31(4)° in 1 and 78.80(7)°/101.20(7)° in 2A and are
3.4. X-ray structures of [Mn(L3)(N3)(HOCH3)0.75(EtOH)0.25)]2 (3) and
[Mn(L4)(N3)(HOCH3)]2 (4)
The manganese atoms have distorted octahedral geometry
involving an N3O3 donor set. Complexes 3 and 4 (Figs. 3 and 4)
consist of l1,1-azido-bridged dinuclear centrosymmetric molecules
in which the MnIII ions are in an axially elongated octahedral
geometry. Each metal atom is coordinated in the equatorial coordi-
nation plane by N2O2 donor atoms from the tridentate hydrazone
ligand (L3)2ꢁ in 3 and (L4)2ꢁ in 4 and one azido atom. Two axial
positions are occupied by an oxygen atom of methanol (ethanol)
and a nitrogen atom of another azido anion with longer distances.
The axially coordinated methanol molecules are hydrogen-bonded
to the pyridyl group of an adjacent dimeric unit in 3 and 4
Fig. 1. Molecular structure of dinuclear [Mn(L1)(N3)(HOCH3)]2 (1); symmetry
transformation: i = 1 ꢁ x, 1 ꢁ y, 1 ꢁ z. Intramolecular hydrogen bonds are shown
as dashed lines.

H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
51
[O2Mꢀ ꢀ ꢀN1ii = 2.684(9) Å (ii = 1 + x, y, z) in 3/O3ꢀ ꢀ ꢀN3i = 2.723(4) Å
(i = x, ꢁ1 + y, z) in 4] to form a one-dimensional chain (Fig. S12
and Table S4). The bond lengths and bonding angles are as ex-
pected for other reported similar Mn complexes and agree with
the coordination of hydrazone ligand in the enol form [49].
3.5. X-ray structure of [Mn2(L2)2(HOCH3)2]n (5)
Fig. 5 shows the coordination diagram of 5 and it displays that
the Mn(II) atom is coordinated by the atoms O1phenol, N2imine
,
O2enol, N3iipy, O1iphenol and O3, which belong to three different
symmetrically dependent doubly deprotonated (L4)2ꢁ anions and
a CH3OH molecule. The data (Table S2) indicate that the coordina-
tion sphere of the Mn1 atom is a distorted octahedron. Fig. 5 also
displays that the atoms O1 and O1i act as bridging atoms between
two Mn(II) ions with a Mn1ꢀ ꢀ ꢀMn1i distance of 3.3740(2) Å, which
creates a coplanar four-membered centrosymmetric ring. From
Fig. 5 it can be derived that a doubly deprotonated (L4)2ꢁ anion acts
as a tetradentate bridging ligand which is bound to three different
Mn atoms through its three O1phenol/N2imine/O2enol atoms and a
pyridyl nitrogen (N3py) atom. In this coordination mode a two-
dimensional sheet structure parallel to [010] was fabricated as
shown in Fig. S13. In the crystal there is one kind of hydrogen
bonds (Table S4). The hydrogen bonds O3–Hꢀ ꢀ ꢀN2i and N2ꢀ ꢀ ꢀH–
O3i (symmetry code i: 1 ꢁ x, y, 0.5 ꢁ z) lead to a connection of adja-
cent sheets and the formation of a supramolecular three-dimen-
sional structure as shown in Fig. S14.
Fig. 4. Dimeric unit of compound [Mn(L4)(N3)(HOCH3)]2 (4) with atom numbering;
symmetry transformation i = 2 ꢁ x, ꢁy, 2 ꢁ z.
3.6. X-ray structure of [Mn(H2L5)2(EtOH)2Cl2] (6)
In complex 6 the manganese atom sits on an inversion center
leading to the trans-configuration of the two chloro, ethanol and
H2L5 ligands (Fig. 6). With a length of >29.17 Å along the H2L5–
Mn–H2L5 axis the metal-complex of trans-[Mn(H2L5)2(OHCH2-
CH3)2Cl2] (6) is one of the longest and anisotropic complex (aspect
ratio 29.17:9.08:4.99) observed so far in Mn-aroylhydrazone com-
plexes. H2L5 coordinates as neutral ligand without deprotonation
in the expected trans-C@N–N–C conformation and hydrogen bond-
ing from the phenolic OH to the azomethine nitrogen atom. The
phenyl and pyridyl rings are in plane with the central hydrazone
moiety. Adjacent molecules are hydrogen bonded through the
coordinated ethanol molecules and form a 1D supramolecule
(Table S4, Fig. S15).
Fig. 5. Diagram of complex [Mn2(L4)2(OHCH3)2]n (5) with the atom numbering
scheme. For clarity the ligands on N3ii have not been completed. The structure is
polymeric; symmetry transformations: i = 1 ꢁ x, ꢁy, 1 ꢁ z; ii = 0.5 + x, ꢁ0.5 ꢁy,
0.5 + z; iii = ꢁ0.5 + x, ꢁ0.5 ꢁ y, ꢁ0.5 + z.
3.7. Magnetic properties
The temperature dependence of the
1 and 2 is shown in Fig. 7. In these compounds the manganese is on
+2 oxidation state. At room temperature the MT values for 1 are
somewhat lower than those expected for two isolated Mn(II) ions
(expected
MT = 4.375 cm3 molꢁ1 K per Mn(II) with g = 2.00 and
S = 5/2). Upon cooling
vMT product for complexes
v
v
v
MT continuously decreases to reach a value
of 4.38 cm3 molꢁ1 K at 2 K. This behavior is indicative of the occur-
rence of weak antiferromagnetic interactions between the Mn(II)
ions in 1. On the other hand the values observed for the vMT prod-
uct of 2 at room temperature are higher than those expected for
two isolated Mn(II) ions and continuously increase on lowering
the temperature to reach a value of 15.0 cm3 molꢁ1 K at 2 K. This
value corresponds to a total spin of S = 5 [
v
MT = 3(Nb2g2/3kT)
S(S + 1) = 15.0 cm3 molꢁ1 K for g = 2.0 and S = 5].
This behavior is indicative of the occurrence of a ferromagnetic
coupling between the Mn(II) ions which ends up with a complete
parallel alignment of the spins in the dinuclear units. The structure
of both compounds consist of Mn(II) dimers and the magnetic sus-
ceptibility data have been analyzed by means of the corresponding
expression for the magnetic susceptibility (1) derived from the
Hamiltonian (2) [2]
Fig. 3. Molecular structure of compound [Mn(L3)(N3)(OHCH3)0.75(EtOH)0.25
] (3)
2
with atom numbering; the major molecule (75% occupancy) of the disordered axial
ligand {CH3OH} is shown, the minor molecule (not shown) is CH3CH2OH with 25%
occupancy. Bond lengths and angles are given in Table S2. Symmetry transforma-
tion i = 1 ꢁ x, 1 ꢁ y, 1 ꢁ z.
2Ng2b2ex þ 5e3x þ 14e6x þ 30e10x þ 55e15x
vM
¼
ð1Þ
KðT ꢁ
H
Þ1 þ 3ex þ 5e3x þ 7e3x þ 9e10x þ 11e15x

52
H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
Fig. 6. (a) Molecular structure of [Mn(H2L5)2(OHCH2CH3)2Cl2] (6) and (b) complex with outer dimensions; symmetry transformation i = 1 ꢁ x, 1 ꢁ y, 1 ꢁ z.
J = 0.94 cmꢁ1. Nevertheless, the predicted values are very close to
those calculated from the magnetic susceptibility data.
^
^ ^
^
H ¼ ꢁJS1S2 þ gbHS
ð2Þ
Where N stands for the Avogadro’s number, b the Bohr magneton,
k the Boltzmann constant, g the Landé factor, x = J/kT and J the mag-
netic coupling constant. A Weiss-like parameter
Figs. 8 and 9 show the temperature dependence of the
vMT
product [vM is the magnetic susceptibility per two Mn(III) ions]
which exhibit room temperature values of 6.01 and 6.10 cm3 -
molꢁ1 K, for 3 and 4 respectively. These values are consistent with
two non-interacting, or weakly interacting, high spin Mn(III) ions
H, has been intro-
duced to take into account interactions among the dinuclear units
in 2. Best fit parameters to Eq. (1) are g = 1.96 (1), J = ꢁ0.12(1) cmꢁ1
,
R = 8.62 ꢂ 10ꢁ5 and g = 2.02(1), J = 1.94(2) cmꢁ1
,
H
= ꢁ0.05(1) K,
(a value of
v
MT = 6.00 cm3 molꢁ1 K is expected for two high spin
R = 2.35 ꢂ 10ꢁ5 for 1 and 2, respectively. [R is the agreement factor
Mn(III) ions in the spin-only model with S = 2 and g = 2.00) [2].
On lowering the temperature, compound 3 exhibits a continuous
P
P
defined as i[(
v
MT)obs(i)ꢁ(
v
MT)calc(i)]2/ i[(
v
MT)obs(i)]2]. The calcu-
lated curves match very well the experimental data in the whole
temperature range as can be seen in Fig. 7.
increase on the
6.45 cm3 molꢁ1 K. Also, compound 4 displays a continuous in-
crease of the
MT product reaching a higher value (9.0 cm3 molꢁ1
vMT product reaching a maximum value of
In general the magnetic coupling constant can be expressed as
the sum of two contributions, a ferromagnetic and an antiferro-
magnetic one J = JF+JAF [2]. The magnetic coupling in EO azido-
bridged Mn(II) dinuclear complexes is dominated by the spin
polarization mechanism, in which the electron on a bridging nitro-
gen has opposite orientation than those of the Mn(II) ions favoring
v
K
at 7 K) and then decreasing at lower temperatures. Both com-
pounds show a ferromagnetic coupling between the Mn(III) ions,
but the coupling is somewhat stronger in 4 since the
vMT product
reaches higher values. The decrease of the MT product at low tem-
v
peratures, shown by 4, occurs due to single ion zero-field-splitting
and/or antiferromagnetic inter-dinuclear interactions [29,51–55].
The magnetic susceptibility data have been analyzed by means
of the Hamiltonian given in Eq. (3) where J corresponds to the mag-
netic coupling constant between the two Mn(III) ions, D and g the
uniaxial anisotropy and the Landé factor of a single Mn(III) ion
respectively, and S1 = S2 = SMn with Siz for the z component of the
Si operator [29,55]
a
ferromagnetic interaction between the metallic ions [50].
Theoretical studies have shown that the magnetic coupling con-
stant increase with the Mn–N–Mn bridging angle (h) with a cross-
over from antiferro- to ferromagnetic coupling around 98°. For
angles smaller than 98° an antiferromagnetic coupling is predicted
whereas for angles larger than 98° a ferromagnetic one is expected
[45]. Even, an equation has been proposed for the J–h relationship,
J = 0.276 hꢁ26.9 (cmꢁ1), however, this equation may be taken with
care since it is an important simplification of the behavior and
must be considered as an indication of the trend more than a tool
to calculate the values of the magnetic coupling constants
[45b,45c]. In the case of compound 1, which displays a Mn–N–
Mn angle of 98.31°, the antiferromagnetic contribution dominates
with J = ꢁ0.12 cmꢁ1 although a value of J = 0.23 cmꢁ1 is predicted.
Whereas, for compound 2 with a Mn–N–Mn angle of 100.88° the
X
X
^
H ¼ ꢁ2JS1S2 þ DMn
S2iZ þ gbH
Si
ð3Þ
i¼1;2
i¼1;2
The dc magnetic susceptibility data were fitted using the
MAGPACK code [56,57]. Intermolecular interactions were not
considered due to the lack of an evident intermolecular ex-
change-path-way and in order to avoid overparameterization in
the calculations. The best sets of parameters obtained are listed
in Table 3.
ferromagnetic one dominates with
a
predicted value of

H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
53
Fig. 9. Temperature dependence of the
vMT product (per dinuclear unit) for
compound 4. The solid line corresponds to the best fit to the model (4), see text. The
inset shows the out of phase magnetic susceptibilities vs. temperature plots for
compound 4 under a dc field of 0 Oe and an ac field of 3.5 Oe.
Some ferromagnetically coupled Mn(III) dinuclear complexes
have been observed to exhibit single molecule magnet (SMM)
behavior [29,55]. In order to explore this possibility, ac magnetic
susceptibility measurements were performed for compounds 3
and 4. Compound 3 did not exhibit any out-of-phase ac signals,
on the other hand, compound 4 exhibited frequency dependent
00
ac signals which shifted the vM values to higher for higher fre-
quencies, inset Fig. 9. However, a maximum for v0M0 was not ob-
served (in the temperature range and frequencies studied), which
suggests the blocking temperature to fall below 2.0 K.
A qualitative explanation for the ferromagnetic coupling ob-
served in 3 and 4 could be as follows. The Mn(III) ion in elongated
Fig. 7. Temperature dependence of the
compounds (a) 1 and (b) 2. The solid line corresponds to the best fit to Eq. (1), see
text.
vMT product (per dinuclear unit) for
1
octahedral geometry displays a t2g3eg electronic configuration
with a 5B1 ground state due to the Jahn–Teller distortion. In these
compounds the bridging azido groups connect an equatorial posi-
tion of a Mn(III) ion (short distance) with an axial position of its
nearest neighbor (long distance). In this sense, the azido bridge is
2
coupling a d orbital (dxydxzdyz) with a dz orbital, which are
p
orthogonal. This coupling usually yields weak ferromagnetic inter-
actions due to the so-called strict orthogonality [2,29,54,58]. Quan-
titatively, the coupling is somewhat stronger in 4 since it exhibits
shorter Mn–Nazido and shorter Mnꢀ ꢀ ꢀMn intramolecular distances.
The temperature evolution of the
pound
T = 8.72(2) cm3 molꢁ1 K which corresponds well with spin-only
value of MT for Mn(II) ions with half-filled d-shell and S = 5/2
(8.76 cm3 molꢁ1 K). At low temperatures, a sharp maximum in
the
vMT product for the com-
5
is shown in Fig. 10. At room temperature, vM-
v
v
MT curve is observed (at ꢄ3 K), indicating the prevalence of
antiferromagnetic exchange interactions. Thus, similarly to all
other compounds studied, the magnetic behavior of the compound
5 is governed by competing ferromagnetic and antiferromagnetic
interactions the strength of which significantly changes with the
Fig. 8. Temperature dependence of the
compound 3 (the solid corresponds to the best fit to Eq. (3)). The inset shows the
field dependence of magnetization of compound 3.
vMT product (per dinuclear unit) for
temperature. Like for compounds 1 and 2, the profile of the
vMT
curve was analyzed by employing Eq. (1). The best fit parameters
to Eq. (1) are g = 2.02(1), J = 0.87(2) cmꢁ1
,
H
= ꢁ0.61(1) K, and
R = 1.82 ꢂ 10–5. The positive value of J implies ferromagnetic inter-
Compounds 3 and 4 display weak ferromagnetic couplings be-
tween the Mn(III) ions with values in the range of other ferromag-
netically coupled azido-bridged Mn(III) dinuclear compounds [29].
The values obtained for the |D| parameter are consistent with the
typical values which range from 0.2 to 2.53 cmꢁ1 for those Mn(III)
dinuclear complexes analogues [54,55]. We can observe that the
calculated curves match very well the experimental data in the
whole temperature range as can be seen in Figs. 8 and 9.
Table 3
Magnetic parameters for compounds 3 and 4.
Compound
g
J (cmꢁ1
)
|D| (cmꢁ1
)
R
3
4
2.00
1.95
0.24
3.23
0.38
0.50
3.20 ꢂ 10ꢁ7
3.05 ꢂ 10ꢁ5

54
H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
These data can be obtained free of charge via http://www.ccdc.ca-
m.ac.uk/conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK;
fax: +44 1223 336 033; or e-mail: deposit@ccdc.cam.ac.uk. Supple-
mentary data associated with this article can be found, in the on-
line version, at http://dx.doi.org/10.1016/j.poly.2013.05.033.
References
[1] M. Viciano Chumillas, S. Tanase, I. Mutikainen, U. Turpeinen, L.J. Jongh, J.
Reedijk, Inorg. Chem. 47 (2008) 5919.
[2] O. Kahn, Molecular Magnetism, Wiley–VCH, 1993.
[3] H. Nagao, M. Nishino, Y. Shigeta, T. Soda, Y. Kitagawa, T. Onishi, Y. Yoshioka, K.
Yamaguchi, Coord. Chem. Rev. 198 (2000) 265.
[4] G. Aromi, M.J. Knapp, J.P. Claude, J.C. Huffman, D.N. Hendrickson, G. Christou, J.
Am. Chem. Soc. 121 (1999) 5489.
[5] A.J. Tasiopoulos, A. Vinslava, W. Wernsdorfer, K.A. Abboud, G. Christou, Angew.
Chem., Int. Ed. 43 (2004) 2117.
[6] P. Kar, P.M. Guha, M.G.B. Drew, T. Ishida, A. Ghosh, Eur. J. Inorg. Chem. (2011)
2075.
[7] C. Beghidja, G. Rogez, J. Kortus, M. Wesolek, R. Welter, J. Am. Chem. Soc. 128
(2006) 3140.
Fig. 10. Temperature dependence of the
compound 5 (the solid corresponds to the best fit to Eq. (1)). The inset shows the
field dependence of magnetization of compound 5.
vMT product (per dinuclear unit) for
[8] M.N. Leuenberger, D. Loss, Nature 410 (2001) 789.
[9] R. Biswas, S. Mukherjee, P. Kar, A. Ghosh, Inorg. Chem. 51 (2012) 8150.
[10] A. Escuer, G. Aromí, Eur. J. Inorg. Chem. (2006) 4721.
[11] S.-Q. Bai, C.-J. Fang, Z. He, E.-Q. Gao, C.-H. Yan, T.S.A. Hor, Dalton Trans. 41
(2012) 13379.
[12] Z.-X. Li, Y.-F. Zeng, H. Ma, X.-H. Bu, Chem. Commun. 46 (2010) 8540.
[13] S.-Q. Bai, C.-J. Fang, Z. He, E.-Q. Gao, C.-H. Yan, T.S.A. Hor, CrystEngComm 15
(2013) 650.
actions favoring parallel arrangement of the binuclear unit.
However, at low temperatures (below 3 K), antiferromagnetic
interactions become strong enough to contribute to the magnetic
response of the compound 5. In increasing applied magnetic fields,
the magnetization of the compound 5 approaches a value of 10 lB
,
[14] F. Meyer, S. Demeshko, G. Leibeling, B. Kersting, E. Kaifer, H. Pritzkow, Chem.
Eur. J. 11 (2005) 1518.
expected for parallel arrangement within the binuclear unit.
[15] P.K. Nanda, G. Aromi, D. Ray, Chem. Commun. (2006) 3181.
[16] C. Adhikary, S. Koner, Coord. Chem. Rev. 254 (2010) 2933.
[17] M. Mohan, M.P. Gupta, L. Chandra, N.K. Jha, Inorg. Chim. Acta 151 (1988) 61.
[18] D.R. Richardson, P. Ponka, Am. J. Hematol. 58 (1988) 299.
[19] D.S. Kalinowski, P.C. Sharpe, P.V. Bernhardt, D.R. Richardson, J. Med. Chem. 51
(2008) 331.
[20] G. Tamasi, L. Chiasserini, L. Savini, A. Sega, R. Cini, J. Inorg. Biochem. 99 (2005)
1347.
[21] M. Bakir, I. Hassan, T. Johnson, O. Brown, O. Green, C. Gyles, M.D. Coley, J. Mol.
Struct. 688 (2004) 213.
[22] O. Pouralimardan, A.-C. Chamayou, C. Janiak, H. Hosseini-Monfared, Inorg.
Chim. Acta 360 (2007) 1599.
[23] M.D. Ward, J. Solid State Electrochem. 9 (2005) 778.
[24] P. Krishnamoorthy, P. Sathyadevi, R.R. Butorac, A.H. Cowley, N.S.P. Bhuvanesh,
N. Dharmaraj, Dalton Trans. 41 (2012) 6842.
[25] M.B. Hursthouse, S.A.A. Jayaweera, A. Quick, Dalton Trans. (1979) 279.
[26] H. Hosseini-Monfared, S. Alavi, A. Farrokhi, M. Vahedpour, P. Mayer,
Polyhedron 30 (2011) 1842.
[27] S. Lin, S.-X. Liu, J.-Q. Huang, C.-C. Lin, Dalton Trans. (2002) 1595.
[28] R. Bikas, H. Hosseini-Monfared, T. Lis, M. Siczek, Inorg. Chem. Commun. 15
(2012) 151.
4. Conclusions
When the four aroylhydrazone Schiff bases were employed in
polynuclear synthesis with azide and Mn(II) (molar ratio 2:3) ions,
the azide bridging ligand gave dinuclear Mn(II) and Mn(III) com-
plexes, whereas using a low ratio of N3ꢁ/Mn(II) gave a 2D coordi-
nation polymer without the azide bridge. Doubly bridged EO
azides transmit ferromagnetic and antiferromagnetic couplings.
In this work, a new two-dimensional manganese(II) coordination
polymer has been synthesized with doubly deprotonated (E)-N0-
(5-bromo-2-hydroxybenzylidene)isonicotinohydrazide, and the
Mn(II) ion assumes a distorted octahedral coordination geometry.
The two dimensional sheets pile up along [101] direction by the
connection of adjacent sheets and form a super-molecular three-
dimensional structure. The hydrogen bond between sheets consol-
idates the crystal.
[29] C.-H. Ge, A.-L. Cui, Z.-H. Ni, Y.-B. Jiang, L.-F. Zhang, J. Ribas, H.-Z. Kou, Inorg.
Chem. 45 (2006) 4883.
[30] A. Ray, C. Rizzoli, G. Pilet, C. Desplanches, E. Garribba, E. Rentschler, S. Mitra,
Eur. J. Inorg. Chem. (2009) 2915.
Acknowledgments
[31] L.N. Dawe, T.S.M. Abedin, T.L. Kelly, L.K. Thompson, D.O. Miller, L. Zhao, C.
Wilson, M.A. Leech, J.A.K. Howard, J. Mater. Chem. 16 (2006) 2645.
[32] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
[33] A. Altomare, M.C. Burla, M. Camalli, G.L. Cascarano, C. Giacovazzo, A.
Guagliardi, A.G.G. Moliterni, G. Polidori, Appl. Crystallogr. 32 (1999) 115.
[34] K. Brandenburg, Diamond (Version 3.2d), Crystal, Molecular Structure
The authors are grateful to the University of Zanjan, Universi-
dad de La Laguna, Palacky University in Olomouc, the Faculty of
Chemistry and Biochemistry of the Ludwig-Maximilians-Universi-
tät München and the School of Chemistry for financial support of
this study. The authors gratefully acknowledge the support by
the Operational Program Research and Development for Innova-
tions – European Development Fund (Project No. CZ.1.05/2.1.00/
03.0058) of the Ministry of Education, Youth, and Sports of the
Czech Republic. We gratefully acknowledge the support by the
Operational Program Research and Development for Innovations-
European Regional Development Fund (project CZ.1.05/2.1.00/
03.0058) and Operational Program Education for Competitiveness
(CZ.1.07/2.3.00/20.0017).
Visualization, Crystal Impact
(Germany), 2009.
– K. Brandenburg & H. Putz Gbr, Bonn
[35] S. Biswas, A.K. Dutta, K. Mitra, M.-C. Dul, S. Dutta, C.R. Lucas, B. Adhikary, Inorg.
Chim. Acta 377 (2011) 56.
[36] C.-M. Liu, D.-Q. Zhang, D.-B. Zhu, Dalton Trans. 39 (2010) 1781.
[37] R. Bikas, H. Hosseini-Monfared, T. Lis, M. Siczek, Acta Crystallogr., Sect. E:
Struct. Rep. Online 68 (2012) o367.
[38] M. Habib, T.K. Karmakar, G. Aromi, J. Ribas-Arino, H.-K. Fun, S.
Chantrapromma, S.K. Chandra, Inorg. Chem. 47 (2008) 4109.
[39] Y. Song, C. Massera, O. Roubeau, P. Gamez, A.M.M. Lanfredi, J. Reedijk, Inorg.
Chem. 43 (2004) 6842.
[40] R.M. Silverstein, F.X. Webster, Spectroscopic Identification of Organic
Compounds, sixth ed., Wiley, New York, 1998. p. 101.
[41] H. Adams, D.E. Fenton, G. Minardi, E. Mura, A.M. Pistuddi, C. Solinas, Inorg.
Chem. Commun. 3 (2000) 24.
[42] G.C. Percy, D.A. Thornton, J. Inorg. Nucl. Chem. 34 (1972) 3369.
[43] G. Kolawole, K.S. Patel, Dalton Trans. (1981) 1241.
[44] S. Banerjee, A. Ray, S. Sen, S. Mitra, D.L. Hughes, R.J. Butcher, S.R. Batten, D.R.
Turner, Inorg. Chim. Acta 361 (2008) 2692.
Appendix A. Supplementary data
CCDC 899445, 899446, 899447, 899926, 899927 and 899448
contains the supplementary crystallographic data for this paper.

H. Hosseini-Monfared et al. / Polyhedron 61 (2013) 45–55
55
[45] (a) Z.-S. Meng, L. Yun, W.-X. Zhang, C.-G. Hong, R. Herchel, Y.-C. Ou, J.-D. Leng,
M.-X. Peng, Z.-J. Lin, M.-L. Tong, Dalton Trans. (2009) 10284;
(b) M.-M. Yu, Z.-H. Ni, C.-C. Zhao, A.-L. Cui, H.-Z. Kou, Eur. J. Inorg. Chem.
(2007) 5670;
[51] R. Boca, Theoretical Foundations of Molecular Magnetism, Elsevier Science SA,
Lausanne, Switzerland, 1999.
[52] Y. Feng, C. Wang, Y. Zhao, J. Li, D. Liao, S. Yan, Q. Wang, Inorg. Chim. Acta 362
(2009) 3563.
(c) T.K. Karmakar, B.K. Ghosh, A. Usman, H.-K. Fun, E. Riviere, T. Mallah, G.
Aromi, S.K. Chandra, Inorg. Chem. 44 (2005) 2391.
[53] G. Bhargavi, M.V. Rajasekharan, J.-P. Costes, J.-P. Tuchagues, Polyhedron 28
(2009) 1253.
[46] S. Ray, S. Konar, A. Jana, S. Jana, A. Patra, S. Chatterjee, J.A. Golen, A.L.
Rheingold, S.S. Mandal, S.K. Kar, Polyhedron 33 (2012) 82.
[47] W.-J. Kang, J.-M. Dou, D.-C. Li, D.-Q. Wang, Acta Crystallogr., Sect. E: Struct.
Rep. Online 63 (2007) o3328.
[48] H. Hosseini-Monfared, R. Bikas, P. Mayer, Acta Crystallogr., Sect. E: Struct. Rep.
Online 66 (2010) o236.
[49] H. Hosseini-Monfared, S. Alavi, R. Bikas, M. Vahedpour, P. Mayer, Polyhedron
29 (2010) 3355.
[50] E. Ruiz, J. Cano, S. Alvarez, P. Alemany, J. Am. Chem. Soc. 120 (1998) 5238.
[54] S. Mandal, A. Rout, K.M. Fleck, G. Pilet, J. Ribas, D. Bandyopadhyay, Inorg. Chim.
Acta 363 (2010) 2250.
[55] Z. Lü, M. Yuan, F. Pan, S. Gao, D. Zhang, D. Zhu, Inorg. Chem. 45 (2006) 3538.
[56] J.J. Borrás-Almenar, J.M. Clemente-Juan, E. Coronado, B.S. Tsukerblat, Inorg.
Chem. 38 (1999) 6081.
[57] J.J. Borrás-Almenar, J.M. Clemente-Juan, E. Coronado, B.S. Tsukerblat, J.
Comput. Chem. 22 (2001) 985.
[58] S. Saha, D. Mal, S. Koner, A. Bhattacherjee, P. Gutlich, S. Mondal, M. Mukherjee,
K.I. Okamoto, Polyhedron 32 (2004) 1811.