Rare examples of diphenoxido-bridged trinuclear NiII2FeIII complexes with a reduced salen type Schiff base ligand: Structures and magnetic properties

Article abstract of DOI:10.1016/j.poly.2017.09.012

Three new trinuclear hetero-metallic complexes, [(NiL^R)₂Fe(N₃)₃] (1), [(NiL^R(H₂O))₂Fe(C₆H₅CH₂CO₂)₂]·(HSO₄) (2) and [(NiL^R(H₂O))₂Fe(C₆H₅CO₂)₂]·(HSO₄)·(H₂O)·(CH₂Cl₂) (3) have been synthesized using [NiL^R] as a “metalloligand” (where H₂L^R = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine). All complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD and magnetic study. In the angular trinuclear units of 1, the two terminals [NiL^R] coordinate through double phenoxido bridges to the central Fe^III ion which is penta-coordinated having terminally coordinated azide ion. The two terminal Ni^II centers are connected to each other and also to neighbouring units through μ_1,3-azido bridges to form an alternating chain. On the other hand, complexes, 2 and 3 are linear discrete trinuclear species [Ni^II–Fe^III–Ni^II] in which two terminal octahedral [NiL^R] units coordinate to the central octahedral Fe^III ion, located on a crystallographic centre of symmetry, through a μ₂-phenoxido oxygen atom and a bridging carboxylato ion. Variable temperature magnetic susceptibility measurements show the presence of antiferromagnetic exchange interactions in 1 mediated through the phenoxido bridges (J₁ = ?33.2 cm^?1,) and μ_1,3-N₃ single bridges (J₂ = ?19.9 cm^?1 and J₃ = ?16.7 cm^?1). On the other hand, compounds 2 and 3 show ferromagnetic coupling interactions mediated through the double phenoxido bridges with J values of +4.9 and +3.0 cm^?1 for 2 and 3, respectively.

Full text of DOI:10.1016/j.poly.2017.09.012

Polyhedron 138 (2017) 145–153
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Rare examples of diphenoxido-bridged trinuclear NiI2IFeIII complexes
with a reduced salen type Schiff base ligand: Structures and magnetic
properties
Alokesh Hazari a,b, Carlos J. Gómez-García c, Michael G.B. Drew d, Ashutosh Ghosh a,
⇑
a Department of Chemistry, University College of Science, University of Calcutta, 92, APC Road, Kolkata 700009, India
b Department of Chemistry, Government General Degree College Singur, Jalaghata, Hooghly, 712 409, India
c Instituto de Ciencia Molecular (ICMol), Dpt. Química Inorgánica, Universidad de Valencia, C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia, Spain
d School of Chemistry, The University of Reading, P.O. Box 224, Whiteknights, Reading RG6 6AD, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Three new trinuclear hetero-metallic complexes, [(NiLR)2Fe(N3)3] (1), [(NiLR(H2O))2Fe(C6H5CH2CO2)2]ꢀ
(HSO4) (2) and [(NiLR(H2O))2Fe(C6H5CO2)2]ꢀ(HSO4)ꢀ(H2O)ꢀ(CH2Cl2) (3) have been synthesized using
[NiLR] as a ‘‘metalloligand” (where H2LR = N,N0-bis(2-hydroxybenzyl)-1,3-propanediamine). All com-
plexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD and
magnetic study. In the angular trinuclear units of 1, the two terminals [NiLR] coordinate through double
phenoxido bridges to the central FeIII ion which is penta-coordinated having terminally coordinated azide
ion. The two terminal NiII centers are connected to each other and also to neighbouring units through
Article history:
Received 8 July 2017
Accepted 11 September 2017
Available online 21 September 2017
Keywords:
Nickel(II)
Iron(III)
l
1,3-azido bridges to form an alternating chain. On the other hand, complexes, 2 and 3 are linear discrete
trinuclear species [NiII–FeIII–NiII] in which two terminal octahedral [NiLR] units coordinate to the central
octahedral FeIII ion, located on a crystallographic centre of symmetry, through a
2-phenoxido oxygen
l1,3-azido bridging
Reduced Schiff base
Magnetic properties
l
atom and a bridging carboxylato ion. Variable temperature magnetic susceptibility measurements show
the presence of antiferromagnetic exchange interactions in 1 mediated through the phenoxido bridges
(J1 = ꢁ33.2 cmꢁ1,) and
l
1,3-N3 single bridges (J2 = ꢁ19.9 cmꢁ1 and J3 = ꢁ16.7 cmꢁ1). On the other hand,
compounds 2 and 3 show ferromagnetic coupling interactions mediated through the double phenoxido
bridges with J values of +4.9 and +3.0 cmꢁ1 for 2 and 3, respectively.
Ó 2017 Elsevier Ltd. All rights reserved.
1. Introduction
transition metals (4d,5d) [6,7] as well as rare earth metals (4f, 5f)
[8,9] are also well known. An important subgroup of the complexes
The design and synthesis of polynuclear metal complexes have
become a very popular research topic in the last decades not only
for their attractive structures but also for their diverse applications
such as optical materials, magnetic materials and catalysts for
organic reactions [1–4]. The knowledge of the magnetic properties
and the factors governing them in polynuclear complexes is a key
factor for the design and development of polynuclear complexes
with interesting and pre-defined magnetic properties in order to
prepare SMM or magnetic MOFs with interesting applications in
magnetic sensors, memory devices, low density magnets, separa-
tion of magnetic molecules etc.
is formed by the hetero-metallic complexes, where almost all pos-
sible combinations of transition metals [10] and/or rare earth met-
als [11,12] are known. For the designed synthesis of such
complexes the choice of ligands is the most important issue. The
salen type di-Schiff base ligands offer a very straight forward
way for such synthesis as the two oxygen atoms of their neutral
mononuclear complexes of divalent metal ions can coordinate
easily to another metal ion to produce hetero-polynuclear com-
plexes [13,14]. Among the divalent 3d transition metal ions, com-
plexes of Cu(II) [15] and Ni(II) [16] are the most stable and
therefore have been widely exploited for this purpose. Recently,
we found that complexes of reduced Schiff bases can also be used
as ‘‘metalloligands” as efficiently as their unreduced analogues
[17]. Moreover, they can bring about interesting variations in the
structures due to increased flexibility of the ligand backbone and
potential formation of hydrogen bonds [18]. A recent search in
The majority of these complexes have been synthesized with
first row transition metals (3d) [5], although complexes of other
⇑
Corresponding author.
E-mail address: ghosh_59@yahoo.com (A. Ghosh).
https://doi.org/10.1016/j.poly.2017.09.012
0277-5387/Ó 2017 Elsevier Ltd. All rights reserved.

146
A. Hazari et al. / Polyhedron 138 (2017) 145–153
the CCDC database for hetero-metallic complexes where Schiff
base complexes of Cu(II) or Ni(II) are connected to any transition
metal atom through the phenoxido bridge locates several dinuclear
[19] and trinuclear, [20] and a few polynuclear [21] species. Among
these, the trinuclear MCu2 [22] or MNi2 [23] (where M = any tran-
sition metal atom other than Cu or Ni) species are the most abun-
dant, especially with salen type Schiff bases. However, when iron is
the hetero-atom (M = Fe), only one trinuclear [24] and one trinu-
clear-based chain structure [25] with Cu(II) but no trinuclear
phenoxido bridged Ni2Fe complex with salen type Schiff base are
reported till date. Although there is one similar trinuclear Ni2Fe
complex but that is derived from a tripodal hexadentate Schiff base
ligand [26].
of 1,3-propanediamine (0.42 mL) was mixed with 10 mmol of the
salicylaldehyde (1.04 mL) in methanol (25 mL). The resulting solu-
tion was refluxed for ca. 2 h and allowed to cool. Then 25 mL
(5 mmol) of this yellow methanolic ligand solution (H2L) was
cooled to 0 °C, and sodium borohydride (456 mg, 12 mmol) was
added to this methanol solution with stirring. After completion
of addition, the resulting solution was acidified with concentrated
HCl (10 mL) and then evaporated to dryness on a hot water bath
[33] The reduced Schiff base ligand H2LR was extracted from the
solid mass with methanol, and this methanol solution (ca. 25 mL,
5 mmol) was reacted with an aqueous solution (15 mL) of
Ni(ClO4)2ꢀ6H2O (1.820 g, 5 mmol) and 10 mL of ammonia solution
(20%) to prepare the ‘‘metalloligand”, [NiLR] as reported earlier
[34].
The phenoxido bridge is well known for transmitting ferro- or
anti-ferromagnetic exchange between paramagnetic metal
centres depending mostly on the bridging angle [23a,27]. The
crossover angles where ferromagnetic coupling changes to anti-
ferromagnetic have been established experimentally and
theoretically for the homo-metallic complexes by various groups
[28]. However, for hetero-metallic complexes such studies are rare,
presumably due to the paucity of synthesized complexes. If we
consider phenoxido bridged NiII/FeIII complexes including all kinds
of ligands, there are a total of 13 complexes [29–31], 12 of which
have been magnetically characterized [26,29–30]. Among these
twelve complexes, eleven are dimers [29,30] and the remaining
one is the previously mentioned trimer [26]. In the dinuclear com-
plexes, the NiAO(phenoxido)AFe bridging angles are found to vary
between 116.43° and 88.67° and the crossover angle has been esti-
mated to be 95.51° [29b]. The magnetic properties of the only
trinuclear complex [26] are rather surprising as it showed anti-
ferromagnetic coupling for a bridging angle of 86.23°, well below
the crossover angle. This surprising result and the lack of other
examples of this kind of polynuclear complexes prompted us to
synthesize some diphenoxido-bridged trinuclear NiII/FeIII com-
plexes in order to study their magnetic coupling.
2.3. Syntheses of the complexes, [(NiLR)2Fe(N3)3] (1), [(NiLR(H2O))2Fe
(C6H5CH2CO2)2]ꢀ(HSO4) (2) and [(NiLR(H2O))2Fe(C6H5CO2)2]ꢀ(HSO4)ꢀ
(H2O)ꢀ(CH2Cl2) (3)
The precursor complex [NiLR] (0.684 g, 2 mmol) was dissolved
in methanol (20 mL) and then an aqueous solution (1 mL) of iron
(III) sulphate (0.399 g, 1 mmol) and an aqueous solution (1 mL)
of sodium azide (0.195 g, 3 mmol), were added to this solution.
The mixture was stirred for 1 h and then filtered. The filtrate was
allowed to stand overnight when deep red coloured micro-crystals
of 1 appeared at the bottom of the beaker. Complexes 2 (red, rhom-
bic) and 3 (red, hexagonal) were prepared using the same synthetic
methods (and the same stoichiometries) as described for 1 but
using sodium phenyl acetate (0.474 g, 3 mmol) and sodium ben-
zoate (0.432 g, 3 mmol) respectively, instead of sodium azide. All
three compounds were re-crystallised from dichloromethane solu-
tion to get X-ray quality single crystals. The crystals (1–3) were
washed with a methanol–water mixture and dried in a desiccator
containing anhydrous CaCl2 and then characterized by elemental
analysis, spectroscopic methods and X-ray diffraction.
Here, we present the syntheses, X-ray crystal structures, and
magnetic properties of three new complexes formulated as
[(NiLR)2Fe(N3)3] (1), [(NiLR(H2O))2Fe(C6H5CH2CO2)2]ꢀ(HSO4) (2)
and [(NiLR(H2O))2Fe(C6H5CO2)2]ꢀ(HSO4)ꢀ (H2O)ꢀ(CH2Cl2) (3) (where
Complex 1
Yield: 1.797 g, 51%. Anal. Calc. for C136H166Fe4N52Ni8O18: C,
46.52; H, 4.75; N, 20.67. Found: C, 46.38; H, 4.88; N, 20.82%; UV–
Vis: kmax in nm (solid, reflectance) = 490 and 349. IR (KBr) in
H2LR = N,N0-bis(2-hydroxybenzyl)-1,3-propanediamine).
These
cmꢁ1
Complex 2
: m(NAH) 3254; m(N3) 2054.
complexes are the first examples of double phenoxido bridged trin-
uclear Ni2Fe units derived from salen type N2O2 donor reduced
Schiff base ligands. Magnetic measurements reveal antiferromag-
netic interactions in complex 1 and ferromagnetic interactions in
complexes 2 and 3, which have been well explained considering
their respective structural parameters.
Yield: 0.743 g, 64%. Anal. Calc. for C50H59FeN4Ni2O15S: C, 51.71;
H, 5.12; N, 4.82. Found: C, 51.76; H, 5.01; N, 4.89%; UV–Vis: kmax in
nm (solid, reflectance) = 510 and 352. IR (KBr) in cmꢁ1
: m(NAH)
3261;
m(C@O) 1569 and 1597.
Complex 3
Yield: 0.836 g, 69%. Anal. Calc. for C49H59FeN4Ni2O15SCl2: C,
48.23; H, 4.87; N, 4.59. Found: C, 48.41; H, 4.93; N, 4.71%; UV–
Vis: kmax in nm (solid, reflectance) = 492 and 350. IR (KBr) in
2. Experimental
cmꢁ1
: m(NAH) 3257; m(C@O), 1553 and 1594.
2.1. Starting materials
Salicylaldehyde, 1,3-propanediamine and sodium borohydride
were purchased from Lancaster and were of reagent grade. They
were used without further purification.
Caution! Azide salts and Perchlorate salts of metal complexes
with organic ligands are potentially explosive. Only a small
amount of material should be prepared and it should be handled
with care.
2.4. Physical measurements
Elemental analyses (C, H, and N) were performed using a
Perkin-Elmer 2400 series II CHN analyzer. IR spectra in KBr pellets
(4000–400 cmꢁ1) were recorded using a Perkin-Elmer RXI FT-IR
spectrophotometer. Electronic spectra in solid state (1200–
300 nm) were recorded in a Hitachi U-3501 spectrophotometer.
The DC magnetic susceptibility measurements were carried out
in the temperature range 2–300 K with an applied magnetic field
of 0.1 T on polycrystalline samples of compounds 1–3 (with
masses of 30.48, 23.58 and 36.83 mg, respectively) with a Quan-
tum Design MPMS-XL-5 SQUID susceptometer. AC susceptibility
measurements were performed on compounds 2 and 3 in the
temperature range 2–10 K with an oscillating field of 3.9 Oe at
2.2. Synthesis of the reduced Schiff base ligand, N,N0-bis(2-
hydroxybenzyl)-1,3-propanediamine (H2LR) and ‘‘metalloligand”,
[NiLR]
The di-Schiff base ligand from 1,3-propanediamine and sali-
cyldehyde was synthesized by a reported method [32]: 5 mmol

A. Hazari et al. / Polyhedron 138 (2017) 145–153
147
110 Hz. The susceptibility data were corrected for the sample
holders previously measured using the same conditions and for
the diamagnetic contributions of the salt as deduced by using
bands at 490, 510 and 492 nm, respectively, while the band max-
ima for the ‘‘metalloligand” [NiLR] appear at 635 nm. These bands
are attributed to d–d transitions of Ni(II) ions in octahedral envi-
ronment. In addition, the three hetero-metallic compounds show
a sharp single absorption maximum near 349, 352 and 350 nm
for 1, 2 and 3, respectively, and the ‘‘metalloligand” [NiLR] shows
an absorption maximum at 349 nm, attributed to ligand-to-metal
charge transfer transitions.
Pascal’s constant tables (
v
dis = ꢁ529.6 ꢂ 10ꢁ6, ꢁ531.6 ꢂ 10ꢁ6 and
ꢁ528.9 ꢂ 10ꢁ6 emumolꢁ1 respectively) [35].
2.5. Crystallographic data collection and refinement
Well formed single crystals of each complex was mounted on a
Bruker-AXS SMART APEX II diffractometer equipped with a gra-
3.3. Description of the structures
phite monochromator and Mo K
a (k = 0.71073 Å) radiation. The
3.3.1. Complex 1
crystals were positioned 60 mm from the CCD, and 360 frames
were measured with a counting time of 5 s. The structures were
solved using the Patterson method through the SHELXS 97 program.
Non-hydrogen atoms were refined with independent anisotropic
displacement parameters, while difference Fourier synthesis and
least-squares refinement showed the positions of remaining
non-hydrogen atoms. The hydrogen atoms bound to carbon atoms
were included in geometric positions and given thermal parame-
ters equivalent to 1.2 (or 1.5 for methyl groups) times those of the
atom to which they were attached. Hydrogen atoms that bonded
to N or O were located in a difference Fourier map where possible
and refined with distance constraints. In 2 and 3, the free anions
were disordered and refined using distance constraints with 50%
occupancy. Successful convergence was indicated by the maxi-
mum shift/error of 0.001 for the last cycle of the least-squares
refinement. Absorption corrections were carried out using the
SADABS program [36], while all calculations were made via SHELXS
97 [37], SHELXL 97 [38], PLATON 99 [39], ORTEP-32 [40], and WINGX
system ver-1.64 [41]. Data collection, structure refinement param-
eters, and crystallographic data for the three complexes are given
in Table S1.
The X-ray crystal structure shows that complex 1 is a
l1,3-N3
bridged 1D chain (Fig. 1) based on trinuclear [(NiLR)2Fe(N3)3] units.
The asymmetric unit consists of four equivalent trinuclear
[(NiLR)2Fe(N3)3] units. The bond parameters are nearly the same
in all four equivalent trinuclear structures; hence here we describe
only one unit which is depicted in Fig. 2. Crystallographic data for
this complex is given in Table S1. Selected bond lengths and angles
are listed in Table S2. In each of the trinuclear units, the three
metal atoms (two terminals Ni and one central Fe) are in a bent
arrangement with \Ni(II)–Fe(III)–Ni(II) angles ranging from 109.4
(1) to 110.4(1)°. The terminal nickel(II) atoms present a distorted
octahedral geometry. The basal plane of the two terminal Ni(II)
centers is formed by two
l2-phenoxido oxygen atoms and two
imine nitrogen atoms of the chelated di-anionic tetradentate
reduced Schiff-base ligand (LR)2ꢁ and the axial positions are occu-
pied by two nitrogen atoms from two l1,3-bridging azido ligands.
The four donor atoms in the equatorial plane around the nickel
atoms show r.m.s. deviations between 0.01 and 0.05 Å in the eight
independent coordination spheres while the nickel atoms deviate
in the range 0.009(3) and 0.029(3) Å from the mean plane. The
two equatorial planes intersect at 83.7(1)–88.1(1)° in the four trin-
uclear molecules. The NiAO [2.039(4)–2.074(4) Å] and NiAN
[2.032(5)–2.072(5) Å] bond distances in the basal plane are very
similar but these are shorter than the axial NiAN bond distances
[2.074(6)–2.168(6) Å] (Table S2). Both the bridging and terminal
azido ligands are within 4° of being linear. The central Fe(1) atom
is penta-coordinated by four phenoxido oxygen atoms of two
reduced Schiff base ligands, and a terminal azido ligand. The dis-
tortions of the coordination geometry from the square pyramid
to the trigonal bipyramid have been calculated by the Addison
3. Results and discussion
3.1. Syntheses of the complexes
The reduced Schiff-base ligand (H2LR) and its metalloligand,
[NiLR] were synthesized using the reported procedures [32–34].
The ‘‘metalloligand”, [NiLR] on reaction with iron(III) sulphate
and sodium azide or sodium phenyl acetate or sodium benzoate
in 2:1:3 molar ratios in MeOH-H2O medium (10:1, v/v) resulted
in three new trinuclear Ni2Fe complexes, [(NiLR)2Fe(N3)3] (1)
[(NiLR(H2O))2Fe(C6H5CH2CO2)2]ꢀ(HSO4) (2) and [(NiLR(H2O))2
Fe(C6H5CO2)2]ꢀ(HSO4)ꢀ(H2O)ꢀ(CH2Cl2) (3) (Scheme 1).
parameter (
between the two largest donor-metal-donor angles divided by
60. The parameter is 0 for the ideal square pyramid and 1 for
the trigonal bipyramid. The values of the four Fe(1) ions range
s) [42]. The value of s is defined as the difference
s
s
from 0.46 to 0.54, indicating that the geometry is intermediate
between the two ideal geometries. The FeAO bond distances
[1.927(4)–2.024(4) Å.] are larger than the FeAN ones [1.900(6)–
1.929(5) Å.]. The metal–metal distances range between 3.074(1)
and 3.120(1) Å.
3.2. IR and UV–Vis spectra
Besides elemental analyses, all three complexes were initially
characterized by IR spectra. The appearance of moderately strong
and sharp peaks at 3254, 3261 and 3257 cmꢁ1 (due to a NAH
stretching vibration) for complexes 1–3, respectively (Figs. S1–S3,
SI) and absence of any peak at around 1620 cmꢁ1 indicate that
the imine group of the Schiff base is reduced [17,18]. The peak at
2054 cmꢁ1 proves the presence of azido coligand for 1. On the
other hand, the presence of carboxylato ligand in complexes 2
and 3 is confirmed by the appearance of strong and sharp peaks
at 1569 and 1553 cmꢁ1 along with shoulders at 1597 and
1594 cmꢁ1, respectively (Figs. S2 and S3, SI). The splitting of the
band is indicative of the presence of two different types (symmet-
ric and asymmetric) stretching vibrations of the carboxylato
coligands.
3.3.2. Complexes 2 and 3
The linear trinuclear structures of 2 and 3 having molecular
formula [(NiLR(H2O))2Fe(C6H5CH2CO2)2]ꢀ(HSO4) (2) and [(NiLR(H2O))2
Fe(C6H5CO2)2]ꢀ(HSO4)ꢀ (H2O)ꢀ(CH2Cl2) (3), respectively, are shown
in Fig. 3 together with the atomic numbering scheme. The selected
bond parameters are summarized in Table S3. Unlike 1, both struc-
tures (2 and 3) contain a crystallographic inversion center at the
central iron atom Fe(1). Thus, the asymmetric unit consists of
two metal centers [Ni(II)-terminal and Fe(III)-central], one depro-
tonated reduced di-Schiff base ligand [(LR)2ꢁ], one bridging car-
boxylato co-anion (phenyl acetato for 2 and benzoato for 3) and
one non-coordinated hydrogen sulphate anion. These free anions
are in general positions with 50% occupancy. In the case of 3 the
The electronic spectra of the three compounds were recorded in
the solid state (Fig. S4). Compounds 1–3 show broad absorption

148
A. Hazari et al. / Polyhedron 138 (2017) 145–153
N
N
N
O
O
H
H
N
N
Ni(II)
(II)Ni
Fe(III)
N
N
N
N
O
O
N
N
N
H
H
N
N
[1]
1. Ni(ClO4)2 .6H2O
2. Fe2(SO4)3
3. Na-azide
(In MeOH/water)
NH
HN
HO
OH
[H2LR]
1. Ni(ClO4)2 .6H2O
2. Fe2(SO4)3
3. Na-Benzoate
(In MeOH/water)
1. Ni(ClO4)2 .6H2O
2. Fe2(SO4)3
3. Na-phenyl acetate
(In MeOH/water)
H
H
H
H
O
H
H
O
H
H
O
O
O
H O
O
O
2
O
OH2
N
(II)
N
N
N
N
N
N
Fe (III)
O
Ni
(II)
Ni
Fe
O
(II)
Ni
(II)
O
(III)
Ni
N
O
H2O
O
O
H2O
O
O
-
-
(HSO4 )
(HSO4 )
[2]
[3]
Scheme 1. Syntheses of complexes 1–3.
Fig. 1. The 1D chain of 1 formed by l1,3-N3 bridging between trinuclear units. Other H-atoms have been removed for clarity.

A. Hazari et al. / Polyhedron 138 (2017) 145–153
149
octahedral geometry. The distorted octahedral geometry of the
nickel atoms in 2 and 3 is confirmed by the root mean squared
(r.m.s.) deviations of the four basal atoms from the mean plane
which are 0.008 and 0.012 Å with the metal atom 0.016(1) and
0.033(1) Å shifted from this mean plane, respectively.
For both structures (2 and 3), and in contrast to 1, the central
Fe(III) atom occupies a crystallographic inversion centre with a dis-
torted octahedral geometry being bonded to four phenoxido oxy-
gen atoms of deprotonated tetradentate reduced Schiff base
ligands and two oxygen atoms of two bridging carboxylato ligands.
The basal Fe(III)AO bond distances [1.978(4)–1.980(4) Å for 2 and
1.970(4)–1.980(4) Å for 3] are similar but shorter than the axial
ones [2.044(4) and 2.041(4) Å for 2 and 3, respectively] resulting
in an axially elongated octahedron. The slight distortion of the
octahedral geometry of Fe(III) is also indicated by the range of cis
angles [83.3(2)–88.1(2)° for 2 and 82.6(2)–89.0(2)° for 3]. The
Fe(1)ꢀ ꢀ ꢀNi(1) distances are 3.029(1) and 3.012(1) Å for 2 and 3,
respectively.
Both structures (2 and 3) contain an intermolecular C–Hꢀꢀꢀ
p
interaction between the centroid of phenyl ring of one unit and a
H-atom of another similar unit with the dimensions C(21)–
H(21B)–CG12, 144.1°; H(21B)–CG12, 2.88 Å; CG12 = C45–C46–
Fig. 2. Ortep structure of one trinuclear complex of 1 with ellipsoids at 30%
probability. There are three other complexes with equivalent geometries in the
asymmetric unit which together form a one-dimensional polymer. The solvent
water molecules are omitted for clarity.
C47–C48–C49–C50 for
H(21A)–CG12, 3.13 Å CG12 = C44–C45–C46–C47–C48–C49 for 3)
(Fig. 4 and Fig. S5, respectively). From the dimensions it is clear
2
and C(21)–H(21A)–CG12, 129.7°,
that this intermolecular C–Hꢀꢀꢀ
p interaction in 2 (Fig. 4) is stronger
than that in 3 (Fig. S5).
In addition, both structures (2 and 3) also contain an inter-
molecular H-bonding interaction between the O atoms [O51 and
O54 for 2; O63 and O64 for 3] of the non-coordinated hydrogen
sulphate anion and the hydrogen atom (H19) of the reduced imine
moiety [N(19)–H(19)ꢀꢀꢀO(51)/O(54) and N(19)–H(19)ꢀꢀꢀO(63)/
O(64)] with the dimensions H19–O51/O54 2.37(5)/2.48(6) Å and
H19–O63/O64 2.28(6)/2.39(9) Å; N(19)–H(19)ꢀꢀꢀO(51)/O(54) 156
(5)°/152(5)° and N(19)–H(19)ꢀꢀꢀO(63)/O(64) 160(7)/150(4)° for 2
and 3, respectively [Figs. S6 and S7].
asymmetric unit contains a water and a dichloromethane molecule
both refined with 50% occupancy. For charge balance the anions in
2 and 3 must be HSOꢁ4 though the hydrogen atom was not located.
For both complexes, the terminal nickel center [Ni(1)] presents a
distorted octahedral geometry. The basal plane of the Ni(1) in each
case is formed by the two imine N atoms and two phenoxido oxy-
gen atoms like 1 but unlike 1 the axial sites are occupied by the
coordination of two O-atoms, one from a bridging carboxylato
ligand and other from a water solvent molecule. All the bond
distances NiAN [2.061(5)–2.063(5) Å for 2 and 2.045(6)–2.079
(6) Å for 3] and NiAO [2.058(4)–2.065(4) Å for 2 and 2.044(4)–
2.053(4) Å for 3] are very close to each other (Table S3), as in 1.
The range of cis angles [79.3(2)–96.8(2)° for 2 and 79.1(2)–
96.3(3)° for 3] and trans angles [170.9(2)–174.7(2)° for 2 and
170.8(3)–174.9(2)° for 3] around the metal centres indicate that
both coordination spheres deviate only slightly from the ideal
3.4. Magnetic properties of the complexes
The thermal variation of the product of the molar magnetic
susceptibility per Ni2Fe trimer times the temperature (vmT) for
compound 1 shows a value of ca. 6.5 cm3 K molꢁ1 at room
temperature, close to the expected value for two isolated Ni(II) ions
Fig. 3. Ortep structures of 2 (left) and 3 (right) with ellipsoids at 30% probability. Symmetry elementsa = 1 ꢁ x,1 ꢁ y,1 ꢁ z and 1/2 ꢁ x,1/2 ꢁ y,1 ꢁ z for 2 and 3, respectively.
Hydrogen sulphate anions in 2 and 3 are not shown for clarity nor are the solvent water molecules.

150
A. Hazari et al. / Polyhedron 138 (2017) 145–153
Fig. 4. The intermolecular C–Hꢀ ꢀ ꢀ
p
interaction between two trinuclear units in 2. Other H-atoms have been removed for clarity.
(ca. 2 cm3 K molꢁ1) plus one isolated Fe(III) ion (ca. 4.4 cm3
K molꢁ1). When the temperature is lowered,
mT shows a progres-
sive and continuous decrease to reach a small plateau of ca.
anti-ferromagnetic [45–53]. On the other side, J2 (ꢁ19.9 cmꢁ1
)
v
and J3 (ꢁ16.7 cmꢁ1), correspond to
l1,3-N3 bridges, which are well
known to give rise to moderate-strong anti-ferromagnetic coupling
when connecting transition metal ions [54–56]. Furthermore, for
0.4 cm3 K molꢁ1 in the range 3–5 K. Below ca. 3 K,
vmT shows an
additional decrease to reach a value of ca. 0.25 cm3 K molꢁ1 at
2 K (Fig. 5). This behaviour suggests the presence of predominant
antiferromagnetic NiAFe exchange interactions in compound 1.
The structure of compound 1 shows the presence of a chain of
single
depends on the M–N–N angle (b) (that indicates the deviation from
linearity of the 1,3-N3 bridge) in such a way that large b values
imply large |J| couplings [55]. This correlation agrees with our
results since the average b angle in the 1,3-N3 bridge correspond-
ing to J2 (b = 57.6°) is larger than the b angle in the 1,3-N3 bridge
l1,3-N3 bridges, the strength of this coupling strongly
l
Ni2Fe trimers connected through
mers present two types of bridges: (i) double phenoxido bridges
between Ni(1)–Fe and Ni(2)–Fe and (ii) a single 1,3-N3 bridge
l1,3-N3 bridges. These Ni2Fe tri-
l
l
l
corresponding to J3 (b = 36.52°) and, accordingly, |J2| is larger than
|J3|. Additionally, the J2 and J3 values are close to those found in
between the two Ni ions. Accordingly, we have fitted the magnetic
properties of compound 1 with a chain of isosceles triangular tri-
mers with three different coupling constants (J1 and J2 to account
for the intra-trimer interactions and J3 for the inter-trimer ones,
see Fig. 6) [43,44]. This model reproduces very satisfactorily the
magnetic properties of compound 1 above ca. 3 K with g = 2.133,
J1 = ꢁ33.2 cmꢁ1, J2 = ꢁ19.9 cmꢁ1 and J3 = ꢁ16.7 cmꢁ1 (solid line in
Fig. 5). Note that in order to reduce the number of adjustable
parameters, we have assumed an average g value for the Ni(II)
and Fe(III) ions.
other Ni(II) complexes with single
angles [55].
l1,3-N3 bridges and similar b
The thermal variation of the product of the molar magnetic sus-
ceptibility per Ni2Fe trimer times the temperature ( mT) for com-
v
pound 2 shows a room temperature value of ca. 6.7 cm3 K molꢁ1
,
close to the expected value for two isolated Ni(II) ions (ca. 2.0 cm3
K molꢁ1) plus a Fe(III) ion (ca. 4.4 cm3 K molꢁ1) (Fig. 7). When the
sample is cooled, the
mum of ca. 8.2 cm3 K molꢁ1 at ca. 8.2 K. Below this temperature
v
mT sharply decreases to reach a value of ca. 5.8 cm3 K molꢁ1 at
vmT product increases and reaches a maxi-
The anti-ferromagnetic coupling found in the three exchange
coupling constants in compound 1 can be rationalized from previ-
ous magneto-structural correlations in double oxido bridges (J1)
2 K. This behaviour indicates the presence of predominant ferro-
magnetic NiAFe exchange interactions in the trimer whereas the
sharp decrease at low temperatures has to be attributed to the zero
field splitting (ZFS) of the resulting S = 9/2 ground spin state in the
cluster. Since this cluster is a centro-symmetric linear trimer with
no interactions between the terminal Ni centers (Fig. 7), we can fit
and in
l1,3-N3 bridges (J2 and J3). Thus, the moderate anti-ferro-
magnetic coupling corresponding to J1 (ꢁ33.2 cmꢁ1) agrees with
the values found in the reported double phenoxido-bridged FeANi
complexes (Table 1). In 1 the NiAOAFe bond angles (in the range
98.4–102.3°) are above the crossing point (ca. 98°) between ferro-
and anti-ferromagnetic coupling and, accordingly, the coupling is
the magnetic properties of compound
2 to a simple linear
NiAFeANi trimer model with the symmetric magnetic scheme
shown in Fig. 7 with only one coupling constant (J) and one average
g value, using the hamiltonian: H = ꢁJ (S1S2 + S2S3) with S1 = S3 = 1
and S2 = 5/2 [43,44]. This model reproduces very satisfactorily the
magnetic properties of compound 2 above the maximum with
g = 2.045, J = +4.9 cmꢁ1 and a 3.0% of paramagnetic contribution
that may be due to the presence of defective clusters or monomeric
species formed from the trimeric Ni2Fe cluster (solid line in Fig. 7).
The weak ferromagnetic coupling found in compound 2 is the
expected type given the NiAOAFe bond angles in compound 2
(97.02(15)° and 97.18(15)°) which are slightly below the crossing
point (ca. 98°) between ferro and antiferromagnetic coupling for
double oxido bridged metal complexes (Table 1) [45–53].
The thermal variation of the product of the molar magnetic sus-
ceptibility per Ni2Fe trimer times the temperature (vmT) for com-
pound 3 is very similar to that of compound 2: it shows a room
temperature value of ca. 6.7 cm3 K molꢁ1, as in 2, and close to the
expected value for two isolated Ni(II) ions and a Fe(III) one
(Fig. 8). When cooling the sample
mum of ca. 9.7 cm3 K molꢁ1 at ca. 4.4 K. At lower temperatures
mT sharply decreases and reaches a value of ca. 8.3 cm3 K molꢁ1
at 2 K. As for 2, the increase in mT indicates the presence of pre-
dominant ferromagnetic NiAFe exchange interactions in the trimer
vmT increases to reach a maxi-
v
v
Fig. 5. Thermal variation of the
line shows the fit to the model (see text). Inset shows the low temperature region.
vmT product per Ni2Fe trimer for compound 1. Solid

A. Hazari et al. / Polyhedron 138 (2017) 145–153
151
Fig. 6. View of the chain of Ni2Fe triangles in 1 showing the magnetic exchange scheme used to fit the magnetic data.
Table 1
Selected structural parameters of previously reported phenoxido-bridged NiII–FeIII complexes and of compounds 1–3.
Complexesa
JNi(II)–Fe(III)
bridging moiety
NiAOAFe
(°)
NiO2Fe dihedral
angle (°)
Refs.
(exptl)/cmꢁ1
1
ꢁ33.2
bis(
l
2-phenoxido)
100.75
116.43
13.82
–
Present work
[30b]
[FeIIINiII(IPCPMP)(OAc)2
(CH3OH)][PF6]
ꢁ11.20
(l
2-phenoxido) and bis(l-acetato)
[FeIII(N3)2(L1)NiII(H2O)2](ClO4)
ꢁ9.22
ꢁ7.10
bis(
bis(
l
l
2-phenoxido)
-phenoxido) and l-{bis(4-nitrophenyl)- phosphato}
99.70
98.79
0.02
8.14
[29b]
[30a]
[FeIII(L2)(BNPP)NiII(H2O)
(l-BNPP)](ClO4)
[FeIII(N3)2(L3)NiII(H2O)
(CH3CN)](ClO4)
ꢁ3.14
bis(l
2-phenoxido)
97.33
0.93
[29c]
[FeIII(NiIIL4)2]NO3ꢀC2H5OH
ꢁ1.85
tris(
l
2-phenoxido)
2-phenoxido) and
86.23
95.24
—
8.73
[31]
[29b]
[FeIII(benzoato)L1NiII(H2O)
0.50
bis(l
l
-benzoato
-acetato
(l
1,3-benzoato)](ClO4)
[FeIII(H2O)L5NiII(OAc)
1.7
bis(l
2-phenoxido) and
l
92.80
—
[29a]
(l-OAc)](ClO4)ꢀ2H2O
3
2
3.0
4.9
5.65
bis(
bis(
bis(
l
l
l
2-phenoxido) and
2-phenoxido) and
2-phenoxido) and
l
l
l
-benzoato
-phenylacetato
-benzoato
97.00
97.10
93.35
16.16
13.96
7.04
Present work
Present work
[29b]
[FeIII(benzoato)L6NiII(H2O)
(l1,3-benzoato)](ClO4)
{[FeIII(OAc)(L3)NiII(H2O)
7.36
bis(
l
2-phenoxido)
l
-acetato; bis(
l
-phenoxido)bis(
l
-acetato)
90.88
4.87
[29c]
(
(
l
l
-OAc)]0.6ꢀ[FeIII(L3)NiII
- OAc)2]0.4}(ClO4)ꢀ1.1H2O
[FeIII(L6)NiII(
lOAc)2]
13.00
14.57
bis(
l
l
2-phenoxido) and
l
-acetato
89.40
88.67
3.00
2.63
[29b]
[29b]
(ClO4)ꢀH2O
[FeIII(L6)NiII(
(ClO4)ꢀH2O
l-OPr)2]
bis(
-phenoxido)bis( -propionato)
l
a
IPCPMP = 2-(N-isopropyl-N-((2-pyridyl)methyl)aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)amino methyl)-4-methylphenol; H2L1 = [2+2] condensation
products of 4-ethyl-2,6-diformylphenol and 1,3-diaminopropane; BNPP = bis(4-nitrophenyl)phosphate; H2L2 = tetraiminodiphenol macrocyclic ligand; H2L3 = [2+2]conden-
sation product of 4-methyl-2,6-diformylphenol and 2,20-dimethyl-1,3-diaminopropane; H3L4 = 1,1,1-tris(N-salicylideneaminomethyl)ethane; H2L5 = tetraaminodiphenol
macrocyclic ligand; H2L6 = [2+2] condensation product of 4-ethyl-2,6-diformylphenol and 2,2-dimethyl-1,3-diaminopropane.
whereas the sharp decrease at low temperatures has to be attribu-
ted to the zero field splitting (ZFS) of the resulting S = 9/2 ground
spin state in the cluster. Since the geometry of the cluster in 3 is
identical to that of 2, we have used the same trimer model to fit
the magnetic data [43,44]. This model reproduces very satisfacto-
rily the magnetic properties of compound 3 above the maximum
with g = 2.044, J = + 3.0 cmꢁ1 and a 1.2% of paramagnetic contribu-
tion that may be due to the presence of defective clusters or mono-
meric species formed from the trimeric Ni2Fe cluster (solid line in
Fig. 8).
(18)° and 97.07(17)°), than in 2 (97.02(15)° and 97.18(15)°). The
lower J value found in 3 (+3.0 cmꢁ1 versus +4.9 cmꢁ1 in 2) may
be due to the lower dihedral angle in the NiO2Fe unit in complex
2 (159.56°) compared to complex 3 (161.82°).
None of these compounds (2 and 3) show an out of phase sus-
ceptibility in the temperature range 2–10 K, precluding the pres-
ence of a single molecule magnet behaviour or a slow relaxation
process.
4. Conclusions
As in 2, the weak ferromagnetic coupling found in compound 3
is the expected type since the NiAOAFe bond angles in compound
3 (96.93(18)° and 97.07(17)°) are also slightly below the crossing
point (ca. 98°) between ferro- and anti-ferromagnetic coupling
for double oxido bridged metal complexes (Table 1) [45–53].
Finally, if we compare the isostructural clusters 2 and 3, we
should expect a slightly larger ferromagnetic coupling in 3 since
the bridging NiAOAFe bond angles are slightly lower in 3 (96.93
The reaction of the ‘‘metalloligand” [NiLR] (where, H2LR = N,N0-
bis(2-hydroxybenzyl)-1,3-propanediamine) with FeIII in presence
of azido or carboxylato ion has yielded three NiI2IFeIII complexes
demonstrating that ‘‘metalloligand” synthetic approach is as effec-
tive for incorporating FeIII as for other metal ions. In all three com-
plexes, the central FeIII ion is connected to two [NiLR] through
double phenoxido bridges and they reperesnt the second examples

152
A. Hazari et al. / Polyhedron 138 (2017) 145–153
– Spain (PrometeoII/2014/076 and ISIC Programs) for financial
support.
Appendix A. Supplementary data
CCDC 1547125ꢁ1547127 contains the supplementary crystal-
lographic data for (1–3). These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at https://doi.org/10.
1016/j.poly.2017.09.012.
References
[1] (a) D.S. Nesterov, O.V. Nesterova, V.N. Kokozay, A.J.L. Pombeiro, Eur. J. Inorg.
Chem. (2014) 4496;
Fig. 7. Thermal variation of the vmT product per Ni2Fe trimer for compound 2. Solid
line shows the best fit to the model (see text). Inset shows the linear Ni2Fe complex
(b) E. Chelebaeva, J. Larionova, Y. Guari, R.A. SaFerreira, L.D. Carlos, F.A.A. Paz,
A. Trifonov, C. Guerin, Inorg. Chem. 47 (2008) 775.
in 2 with the magnetic exchange scheme used to fit the magnetic data (similar to 3).
[2] (a) M.L. Saha, X. Yan, P.J. Stang, Acc. Chem. Res. 49 (2016) 2527;
(b) P.G. Lacroix, I. Malfant, J.-A. Real, V. Rodriguez, Eur. J. Inorg. Chem. (2013)
615.
[3] (a) C.N. Verani, E. Bothe, D. Burdinski, T. Weyhermüller, U. Flörke, P.
Chaudhuri, Eur. J. Inorg. Chem. (2001) 2161;
(b) R. Biswas, Y. Ida, M.L. Baker, S. Biswas, P. Kar, H. Nojiri, T. Ishida, A. Ghosh,
Chem. Eur. J. 19 (2013) 3943.
[4] (a) E.I. Solomon, U.M. Sundaram, T.E. Machonkin, Chem. Rev. 96 (1996) 2563;
(b) J.I. van der Vlugt, Eur. J. Inorg. Chem. (2012) 363.
[5] (a) S.J. Malthus, S.A. Cameron, S. Brooker, Coord. Chem. Rev. 316 (2016) 125;
(b) M. Atanasov, D. Aravena, E. Suturina, E. Bill, D. Maganas, F. Neese, Coord.
Chem. Rev. 289 (2015) 177.
[6] (a) F. Pointillart, Y. Le Gal, S. Golhen, O. Cador, L. Ouahab, Inorg. Chem. 47
(2008) 9730;
(b) F. Otte, P. Ferriani, S. Heinze, Phy. Rev. B. 89 (2014) 205426 (1–19).
[7] (a) V. Hoeke, A. Stammler, H. Bogge, J. Schnack, T. Glaser, Inorg. Chem. 53
(2014) 257;
(b) R.S. Evans, A.F. Schreiner, Inorg. Chem. 14 (1975) 1705.
[8] (a) N.C. Martinez-Gomez, H.N. Vu, E. Skovran, Inorg. Chem. 55 (2016) 10083;
(b) C. Cruz, E. Spodine, A. Vega, D. Venegas-Yazigi, V. Paredes-Garcia, Cryst.
Growth. Des. 16 (2016) 2173.
[9] (a) L. Chatelain, J.P.S. Walsh, J. Pecaut, F. Tuna, M. Mazzanti, Angew. Chem. Int.
Ed. 53 (2014) 13434;
(b) S.G. Minasian, J.L. Krinsky, J.D. Rinehart, R. Copping, T. Tyliszczak, M.
Janousch, D.K. Shuh, J. Arnold, J. Am. Chem. Soc. 131 (2009) 13767;
(c) S.A. Kozimor, B.M. Bartlett, J.D. Rinehart, J.R. Long, J. Am. Chem. Soc. 129
(2007) 10672.
Fig. 8. Thermal variation of the vmT product per Ni2Fe trimer for compound 3. Solid
line shows the best fit to the model (see text).
[10] (a) F. Walz, E. Moos, D. Garnier, R. Köppe, C.E. Anson, F. Breher, Chem. Eur. J. 23
(2017) 1173;
(b) L.-Q. Chai, L.-J. Tang, L.-C. Chen, J.-J. Huang, Polyhedron 122 (2017) 228.
[11] (a) C. Benelli, D. Gatteschi, Chem. Rev. 102 (2002) 2369;
(b) M. Andruh, J.P. Costes, C. Diaz, S. Gao, Inorg. Chem. 48 (2009) 3342.
[12] (a) M. Maity, M.C. Majee, S. Kundu, S.K. Samanta, E.C. Sanudo, S. Ghosh, M.
Chaudhury, Inorg. Chem. 54 (2015) 9715;
of such NiI2IFeIII species considering all kind of ligands and the first
one with salen type reduced Schiff base ligands. Among the com-
plexes, in 1, the l
1,3-azido bridge not only connects the terminal NiII
centers within the trimer but it also joins the trinuclear units
through Ni(II) to form a very rare type of chain for this type of ligand.
On the other hand, in complexes 2 and 3, the terminal NiII and cen-
tral FeIII are additionally bridged by carboxylato ions which is rather
(b) F. Evangelisti, R. More, F. Hodel, S. Luber, G.R. Patzke, J. Am. Chem. Soc. 137
(2015) 11076;
(c) S. Ghosh, S. Biswas, A. Bauzá, M. Barceló-Oliver, A. Frontera, A. Ghosh,
Inorg. Chem. 52 (2013) 7508.
[13] (a) L.K. Das, A. Biswas, A. Frontera, A. Ghosh, Polyhedron 52 (2013) 1416;
(b) A. Hazari, L.K. Das, A. Bauzá, A. Frontera, A. Ghosh, Dalton Trans. 45 (2016)
5730.
[14] C. Chen, D. Huang, X. Zhang, F. Chen, H. Zhu, Q. Liu, C. Zhang, D. Liao, L. Li, L.
Sun, Inorg. Chem. 42 (2003) 3540.
[15] (a) S. Ghosh, S. Giri, A. Ghosh, Polyhedron 102 (2015) 366;
(b) A. Hazari, A. Ghosh, Polyhedron 87 (2015) 403;
(c) L.K. Das, A. Ghosh, CrystEngComm 15 (2013) 9444.
[16] (a) L.K. Das, M.G.B. Drew, A. Ghosh, Inorg. Chim. Acta 394 (2013) 247;
(b) S. Ghosh, S. Mukherjee, P. Seth, P.S. Mukherjee, A. Ghosh, Dalton Trans. 42
(2013) 13554.
[17] (a) A. Hazari, L.K. Das, A. Bauzá, A. Frontera, A. Ghosh, Dalton Trans. 43 (2014)
8007;
(b) A. Hazari, S. Giri, C. Diaz, A. Ghosh, Polyhedron 118 (2016) 70.
[18] (a) A. Hazari, L.K. Das, R.M. Kadam, A. Bauzá, A. Frontera, A. Ghosh, Dalton
Trans. 44 (2015) 3862;
(b) A. Hazari, A. Das, P. Mahapatra, A. Ghosh, Polyhedron 134 (2017) 99.
[19] (a) P. Bhowmik, S. Jana, P.P. Jana, K. Harms, S. Chattopadhyay, Inorg. Chem.
Commun. 18 (2012) 50;
usual. In complex 1, both the phenoxido bridges and
l1,3-azido
bridges mediate anti-ferromagnetic coupling, in good agreement
with the magneto-structural correlations from the phenoxido bridg-
ing angles (98.4–102.3°) and M–N–N angles (for azido). The phenox-
ido bridging angles in 2 and 3 are ca. 97° and the coupling is
ferromagnetic which indicates that crossover angle is higher than
97° in these species. However, one should be cautious as the cross-
over angle can vary depending on other structural factors such as
the dihedral angles in the central NiO2Fe unit and the NiAO and
FeAO bond distances.
Acknowledgements
The authors thank the Department of Science and Technology
(DST – India), New Delhi, India, for financial support (SR/S1/
IC/0034/2012). We also acknowledge the Generalitat Valenciana
(b) Z.-L. You, Y. Lu, N. Zhang, B.-W. Ding, H. Sun, P. Hou, C. Wang, Polyhedron
30 (2011) 2186;
(c) G.A. Brewer, E. Sinn, Inorg. Chem. 26 (1987) 1529.

A. Hazari et al. / Polyhedron 138 (2017) 145–153
153
[20] (a) F. Ercan, D. Ulku, O. Atakol, F.N. Dincer, Acta Crystallogr., Sect. C: Cryst.
Struct. Commun. 54 (1998) 1787;
(b) C. Fukuhara, K. Tsuneyoshi, N. Matsumoto, S. Kida, M. Mikuriya, M. Mori, J.
Chem. Soc., Dalton Trans. (1990) 3473.
[21] (a) L.K. Das, C.J. Gómez-García, M.G.B. Drew, A. Ghosh, Polyhedron 87 (2015)
311;
[31] S.C. Batista, A. Neves, A.J. Bortoluzzi, I. Vencato, R.A. Peralta, B. Szpoganicz, V.V.
E. Aires, H. Terenzi, P.C. Severino, Inorg. Chem. Commun. 6 (2003) 1161.
[32] L.K. Das, S.-W. Park, S.J. Cho, A. Ghosh, Dalton. Trans. 41 (2012) 11009.
[33] (a) A. Biswas, M.G.B. Drew, A. Ghosh, Polyhedron 29 (2010) 1029;
(b) G.J.B. Colpas, J. Hamstra, J.W. Kampf, V.L. Pecoraro, Inorg. Chem. 33 (1994)
4669.
(b) H. Oshio, M. Nihei, S. Koizumi, T. Shiga, H. Nojiri, M. Nakano, N. Shirakawa,
M. Akatsu, J. Am. Chem. Soc. 127 (2005) 4568;
[34] O. Atakol, H. Nazir, C. Arici, S. Durmus, I. Svoboda, H. Fuess, Inorg. Chim. Acta
342 (2003) 295.
(c) C.N. Verani, E. Rentschler, T. Weyhermuller, E. Bill, P. Chaudhuri, J. Chem.
Soc., Dalton Trans. (2000) 251.
[22] (a) L.K. Das, R.M. Kadam, A. Bauzá, A. Frontera, A. Ghosh, Inorg. Chem. 51
(2012) 12407;
(b) S. Ghosh, G. Aromí, P. Gamez, A. Ghosh, Eur. J. Inorg. Chem. (2015) 3028.
[23] (a) P. Seth, A. Figuerola, J. Jover, E. Ruiz, A. Ghosh, Inorg. Chem. 53 (2014)
9296;
[35] G.A. Bain, J.F. Berry, J. Chem. Educ. 85 (2008) 532.
[36] SAINT, version 6.02; SADABS, version 2.03, Bruker AXS Inc, Madison, WI,
(2002).
[37] G.M. Sheldrick, SHELXS 97, University of Göttingen, Germany, Program for
Structure Solution, 1997.
[38] G.M. Sheldrick, SHELXL 97, University of Göttingen, Germany, Program for
Crystal Structure Refinement, 1997.
(b) L.K. Das, A. Biswas, C.J. Gómez-García, M.G.B. Drew, A. Ghosh, Inorg. Chem.
53 (2014) 434;
(c) F. Ercan, M.B. Ates, Y. Ercan, S. Durmus, O. Atakol, Cryst. Res. Technol. 39
(2004) 470.
[39] A.L. Spek, J. Appl. Crystallogr. 36 (2003) 7.
[40] L.J.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565.
[41] L.J.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[42] A.W. Addison, T.N. Rao, J. Reedijk, J.V. Rijn, G.C. Verschoor, J. Chem. Soc., Dalton
Trans. (1984) 1349.
[43] J.J. Borrás-Almenar, J.M. Clemente-Juan, E. Coronado, B.S. Tsukerblat, Inorg.
Chem. 38 (1999) 6081.
[24] G.A. Brewer, E. Sinn, Inorg. Chim. Acta 134 (1987) 13.
[25] I. Morgenstern-Badarau, D. Laroque, E. Bill, H. Winkler, A.X. Trautwein, F.
Robert, Y. Jeannin, Inorg. Chem. 30 (1991) 3180.
[26] T. Kobayashi, T. Yamaguchi, H. Ohta, Y. Sunatsuki, M. Kojima, N. Re, M.
Nonoyama, N. Matsumoto, Chem. Commun. (2006) 1950.
[27] P. Seth, A. Figuerola, J. Jover, E. Ruiz, A. Ghosh, Polyhedron 117 (2016) 57.
[28] (a) Z. Lu, M. Yuan, F. Pan, S. Gao, D. Zhang, D. Zhu, Inorg. Chem. 45 (2006)
3538;
[44] J.J. Borrás-Almenar, J.M. Clemente-Juan, E. Coronado, B.S. Tsukerblat, J.
Comput. Chem. 22 (2001) 985.
[45] M.A. Halcrow, J. Sun, J.C. Huffman, G. Christou, Inorg. Chem. 34 (1995) 4167.
[46] J.M. Clemente-Juan, B. Chansou, B. Donnadieu, J. Tuchagues, Inorg. Chem. 39
(2000) 5515.
(b) R. Biswas, P. Kar, Y. Song, A. Ghosh, Dalton Trans. 40 (2011) 5324;
(c) D.V. Yazigia, D. Aravenab, E. Spodineb, E. Ruiz, S. Alvarez, Coord. Chem. Rev.
254 (2010) 2086.
[47] L.K. Das, C.J. Gómez-García, A. Ghosh, Dalton Trans. 44 (2015) 1292.
[48] J.M. Clemente-Juan, E. Coronado, J.R. Galán-Mascarós, C.J. Gómez-García, Inorg.
Chem. 38 (1999) 55.
[29] (a) S.K. Dutta, R. Werner, U. Florke, S. Mohanta, K.K. Nanda, W. Haase, K. Nag,
Inorg. Chem. 35 (1996) 2292;
[49] C.J. Gómez-García, E. Coronado, L. Ouahab, Angew. Chem. Int. Ed. 31 (1992)
649.
(b) S. Sasmal, S. Roy, L. Carrella, A. Jana, E. Rentschler, S. Mohanta, Eur. J. Inorg.
Chem. (2015) 680;
[50] C.J. Gómez-García, J.J. Borrás-Almenar, E. Coronado, L. Ouahab, Inorg. Chem. 33
(1994) 4016.
(c) S. Hazra, S. Bhattacharya, M.K. Singh, L. Carrella, E. Rentschler, T.
Weyhermueller, G. Rajaraman, S. Mohanta, Inorg. Chem. 52 (2013) 12881.
[30] (a) S. Dutta, P. Biswas, Polyhedron 31 (2012) 110;
(b) M. Jarenmark, M. Haukka, S. Demeshko, F. Tuczek, L. Zuppiroli, F. Meyer, E.
Nordlander, Inorg. Chem. 50 (2011) 3866;
[51] S. Shit, M. Nandy, G. Rosair, C.J. Gómez-García, J.J.B. Almenar, S. Mitra,
Polyhedron 61 (2013) 73.
[52] A.K. Sharma, F. Lloret, R. Mukherjee, Inorg. Chem. 52 (2013) 4825.
[53] A.K. Sharma, F. Lloret, R. Mukherjee, Inorg. Chem. 46 (2007) 5128.
[54] Y. Zeng, X. Hu, F. Liu, X. Bu, Chem. Soc. Rev. 38 (2009) 469.
[55] F.F. De Biani, E. Ruiz, J. Cano, J.J. Novoa, S. Alvarez, Inorg. Chem. 39 (2000) 3221.
[56] J. Ribas, A. Escuer, M. Monfort, R. Vicente, R. Cortés, L. Lezama, T. Rojo, Coord.
Chem. Rev. 193–195 (1999) 1027.
T.R. Holman, C. Juarez-Garcia, M.P. Hendrich, L. Jr, E.Munck Que, J. Am. Chem.
Soc. 112 (1990) 7611.