Synthesis and characterisation of Fe(III) and Co(III) complexes of thiazole-containing thiosemicarbazone ligands

Article abstract of DOI:10.1016/j.ica.2017.04.008

Three thiosemicarbazone-based ligands and corresponding Fe(III) and Co(III) coordination complexes have been synthesised and fully characterised. Crystallographic analysis of all ligands and complexes revealed interesting hydrogen bonding and π-stacking p

Full text of DOI:10.1016/j.ica.2017.04.008

Accepted Manuscript
Research paper
Synthesis and characterisation of Fe(III) and Co(III) complexes of thiazole-
containing thiosemicarbazone ligands
Robert J. Laverick, Anthony B. Carter, Harry A. Klein, Anthony J. Fitzpatrick,
Tony D. Keene, Grace G. Morgan, Jonathan A. Kitchen
PII:
S0020-1693(17)30167-6
http://dx.doi.org/10.1016/j.ica.2017.04.008
ICA 17512
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
3 February 2017
4 April 2017
5 April 2017
Please cite this article as: R.J. Laverick, A.B. Carter, H.A. Klein, A.J. Fitzpatrick, T.D. Keene, G.G. Morgan, J.A.
Kitchen, Synthesis and characterisation of Fe(III) and Co(III) complexes of thiazole-containing thiosemicarbazone
ligands, Inorganica Chimica Acta (2017), doi: http://dx.doi.org/10.1016/j.ica.2017.04.008
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Synthesis and characterisation of Fe(III) and Co(III) complexes of thiazole-
containing thiosemicarbazone ligands
Robert J. Lavericka, Anthony B. Cartera, Harry A. Kleina, Anthony J. Fitzpatrickb, Tony D. Keeneb, Grace
G. Morganb, Jonathan A. Kitchena*
aChemistry, University of Southampton, Southampton, SO17 1BJ, UK.
bSchool of Chemistry, University College Dublin, Dublin 4, Ireland.
ABSTRACT
Three thiosemicarbazone-based ligands and corresponding Fe(III) and Co(III) coordination complexes have been synthesised and fully
characterised. Crystallographic analysis of all ligands and complexes revealed interesting hydrogen bonding and π-stacking packing
arrangements. Magnetic susceptibility and EPR measurements indicate that the Fe(III) complexes are in the low spin state from 4 – 300
K. The complexes exhibit significant solution stability (based on UV/vis and NMR data) and the potential for further functionalisation.
Such stability gives solution processability and is ideal for the development of advanced supramolecular materials.
thiosemicarbazone ligands
complexation with Fe(III) and Co(III).
(
L1-L3
,
Fig. 1) and their
The magnetic
1. Introduction
properties of the Fe(III) systems are reported, whilst the low-
spin Co(III) systems are reported as a diamagnetic system to
the study of solution behavior by NMR techniques. L1 has
The development of metallosupramolecular assemblies has
attracted the interest of scientists for many years and there is
now a drive towards developing functional assemblies for
supramolecular materials based applications.
choice of the metal ion a range of applications can be
targeted including luminescent systems, catalysts, and
magnetically interesting systems.
based ligands have been used to generate interesting
complexes with a range of potential applications, however
one area that appeals to us is their use in Fe(III) spin-
33
previously been synthesised by Raposo et al
.
and used as
1–4
By careful
part of
a
study for the recognition of anions. L3 has
34
previously been synthesised by Venkatraman et al
.
(as a
different polymorph) and used in complexation studies with
5–8 9–11
.
Thiosemicarbazone-
35–38
Ni, Cd, Sn, and Hg.
However, neither of these studies
investigated iron or cobalt complexes for use in
supramolecular materials.
12–17
crossover (SCO) systems.
Most examples of
thiosemicarbazone-based SCO active complexes use simple
thiosemicarbazides and salicylaldehyde (SA) derivatives (e.g.
Hthsa, Hth5Clsa and Hth5Brsa, Fig. 1). To the best of our
knowledge, and despite the large numbers of heterocyclic
aldehydes and ketones now available, there have been few
studies that have used carbonyl compounds other than SA for
investigation into magnetically interesting Fe(III) complexes.
Additionally, for SCO-based systems to be useful in areas of
nano-technology, solution processability would be
advantageous as it allows for simple immobilisation
into/onto substrates. Many of the magnetically interesting
systems developed to date are significantly labile in solution
and undergo ligand displacement giving SCO inactive
Fig. 1 Thiosemicarbazone ligands known to induce SCO in Fe(III) [Hthsa,
Hth5Clsa, Hth5Brsa] (left) and ligands used in this study (right).
18–22
compounds.
Therefore developing new ligand systems
that can afford favourable coordination environments for
SCO and solution stability represents a major challenge in
SCO research. Furthermore, ligands that have the ability to be
further functionalized (through substituent addition) to
allow for targeted immobilization is also desirable, therefore
synthetic simplicity and modular synthesis is highly
desirable. Thiosemicarbazone-based ligands are ideal for
such a purpose as they are readily and reliably constructed
2. Experimental
2.1 General
All reagents were purchased from commercial sources and used
without further purification. 1H, and 13C{1H} NMR spectra were
recorded on a Bruker DPX400 NMR spectrometer at 300 K.
Chemical shifts are reported in parts per million and referenced to
the residual solvent peak (d6-DMSO: 1H δ 2.50 ppm, 13C δ 39.52
ppm). Coupling constants (J) are reported in Hertz (Hz). Standard
from simple precursors allowing introduction of a large
23–32
range of substituents.
characterization
Here we report the synthesis and
three thiazole containing
of
1

conventions indicating multiplicity were used: m = multiplet, t = 1, Dcalc = 1.464 g/cm3, 8078 reflections measured (4.962° ≤ 2Θ ≤
triplet, d = doublet, s = singlet, dd[appt] = doublet of doublets 55.082°), 2728 unique (Rint = 0.0273, Rsigma = 0.0221) which were
which appears as a triplet. Infrared spectra were recorded using a used in all calculations. The final R1 was 0.0276 (I > 2σ(I))
and wR2 was 0.0715 (all data).
ThermoScientific Nicolet iS10 FTIR spectrometer between 600
and 4000 cm-1. Mass spectrometry samples were analysed using a
MaXis (Bruker Daltonics, Bremen, Germany) mass spectrometer
equipped with a Time of Flight (TOF) analyser. Samples were
introduced to the mass spectrometer via a Dionex Ultimate 3000
autosampler and uHPLC pump [Gradient 20% acetonitrile (0.2%
formic acid) to 100% acetonitrile (0.2% formic acid) in five
minutes at 0.6 mL min-1. Column: Acquity UPLC BEH C18 (Waters)
1.7 micron 50 x 2.1mm]. High-resolution mass spectra were
recorded using positive/negative ion electrospray ionisation.
Single-crystal X-ray diffraction data was collected at 100 K on a
Rigaku AFC12 goniometer equipped with an enhanced sensitivity
(HG) Saturn 724+ detector mounted at the window of an FR-E+
Superbright Mo-Kα rotating anode generator (λ = 0.71075 Å) with
HF or VHF varimax optics.39 Unit cell parameters were refined
against all data and an empirical absorption correction applied in
either CrystalClear40 or CrysalisPro.41 All structures were solved
2.2.2 Synthesis of L2: To
a
stirred solution of 4-
phenylthiosemicarbazide (200 mg, 1.20 mmol) in methanol (30
mL), 4-methyl-2-thiazolecarboxaldehyde (129 μL, 1.20 mmol)
was added. The solution was stirred for 24 hours. The resulting
dark yellow solution was concentrated in vacuo, leaving a dark
yellow oil. This was triturated in diethyl either (20 mL) and
decanted before being recrystallized from methanol (20 mL)
resulting in a dark yellow crystalline solid. Yield: 133 mg (48%);
HRMS ESI+ m/z: 299.0395 [L2 + Na]+, C12H12N4S2Na requires:
299.0396; IR: ν = 3317, 3107, 3054, 1596, 1538, 1236, 1176,
1165, 1031 cm-1; λmax (MeOH) =349 nm, ε = 22,600 Lmol-1cm-1; 1H
NMR (300 MHz, DMSO-d6) δ 12.05 (s, 1H, NH), 10.04 (s, 1H, NH),
8.33 (s, 1H, ImH), 7.54 (m, 2H, PhH), 7.40 – 7.34 (m, 3H, PhH &
ThiaH), 7.24-7.19 (m, 1H, PhH), 2.39 (s, 3H, MethylH). 13C NMR
(101 MHz, DMSO-d6): 17.17, 117.17, 126.00. 126.29, 128.61,
137.83, 139.36, 153.85, 163.07, 176.66. Orange rod-like crystals
2
by direct methods using SHELXS-201342 and refined on FO by
SHELXL-201342 using Olex2.43 The crystallographic data are
summarised below. CCDC entries 1498845 - 1498852 contain the
crystallographic data for the structures reported in this article.
(0.27
recrystallisation
×
0.05
×
0.04 mm) of L2 were obtained from hot
from methanol. Crystal Data for
C12H12N4S2 (M =276.38 g/mol): orthorhombic, space group
P212121 (no. 19), a = 5.004(5) Å, b = 15.83(2) Å, c = 16.73(2) Å, V =
1325(3) Å3, Z = 4, T = 373.3 K, μ(MoKα) = 0.389 mm-1, Dcalc =
1.385 g/cm3, 4836 reflections measured (5.694° ≤ 2Θ ≤ 50.988°),
2427 unique (Rint = 0.0305, Rsigma = 0.0489) which were used in all
calculations. The final R1 was 0.0440 (I > 2σ(I)) and wR2 was
0.0767 (all data).
UV-Vis absorption spectra were recorded on a PerkinElmer
Lambda 265 Spectrophotometer between 200 and 900 nm.
Variable temperature magnetic susceptibility for crystalline
samples of all three Fe(III) complexes were recorded on a
Quantum Design MPMS® XL-7 SQUID magnetometer at 0.1 T.
Magnetic susceptibility was recorded in the range of 400 to 10 K
at 3 K/min temperature scan rate. EPR data was collected
between 283 and 373 K on a polycrystalline sample using a
Magnettech mS200 X-band EPR working at 9.381 GHz with
2.2.3 Synthesis of L3: To
a
stirred solution of 4-
magnetic field centred at 300 mT and a field sweep of 400 mT. phenylthiosemicarbazide (100 mg, 0.6 mmol) in ethanol (10 mL),
Modulation amplitude of 0.5 mT was used in conjunction with a 2-acetylthiazole (70 μL, 0.6 mmol) was added. The solution was
microwave power of 0.1 mW and a gain of 10.
refluxed for 3 hours. The solution was concentrated resulting in
the precipitation of a yellow crystalline solid that was filtered,
washed with diethyl ether (2 x 25 mL) and dried in vacuo. Yield
84 mg, 51%. HRMS ESI+ m/z: 277.0574 [L3 + H]+, C12H13N4S2
2.2 Ligand Synthesis
2.2.1 Synthesis of L1: To
a
stirred solution of 4-
requires: 277.0576; IR ν = 3238, 3112, 3037, 1651, 1479, 1371,
phenylthiosemicarbazide (200 mg, 1.20 mmol) in methanol (30 1046 cm-1 ; λmax (MeOH) =339 nm, ε = 20,500 Lmol-1cm-1; H NMR
mL), 2-thiazolecarboxaldehyde (105 μL, 1.20 mmol) was added. (400 MHz, DMSO-d6) δ 11.01 (s, 1H, NH), 9.92 (s, 1H, NH), 7.91 (d,
The light yellow solution was left to stir for 24 hours. The J = 3.2 Hz, 1H, ThiaH), 7.82 (d, J = 3.2 Hz, 1H, ThiaH), 7.63 – 7.59
1
resulting dark yellow solution was concentrated in vacuo
(m, 2H, PhH), 7.38 (dd[appt], J = 8.1 Hz, 2H, PhH), 7.23 – 7.19 (m,
resulting in the precipitation of a yellow solid. This was filtered 1H, PhH), MethylH signal masked by solvent peaks. 13C NMR (101
and then washed with diethyl ether (2 x 25 mL), the resulting MHz, DMSO-d6) δ 14.44, 123.22, 125.53, 125.89, 128.72, 139.36,
yellow solid was crystallized from methanol (20 mL) resulting in a
light yellow crystalline solid suitable for single crystal X-ray
143.82, 145.57, 167.25, 177.30. Yellow plate like crystals (0.4 ×
0.2 × 0.09 mm) of L3 were grown from the slow evaporation of
diffraction. Yield: 181 mg (69%); HRMS ESI+ m/z: 285.0234 [L1 + methanol. Crystal Data for C12H12N4S2 (M =276.37 g/mol):
Na]+, C11H10N4S2Na requires: 285.0239; IR: ν = 3322, 3297, 3054, triclinic, space group P-1 (no. 2), a = 8.211 Å, b = 8.581 Å, c =
1634, 1598, 1279, 1176, 1166, 1013 cm-1; λmax (MeOH) =343 nm, ε 9.241 Å, α = 85.44°, β = 79.51°, γ = 80.63°, V = 630.8 Å3, Z = 2, T =
= 21,500 Lmol-1cm-1; 1H NMR (400 MHz, DMSO-d6): δ 12.09 (s, 1H, 100 K, μ(MoKα) = 0.408 mm-1, Dcalc = 1.455 g/cm3, 5325
NH), 10.10 (s, 1H, NH), 8.39 (s, 1H, ImH), 7.96 (d, J = 3.2 Hz, 1H, reflections measured (6.192° ≤ 2Θ ≤ 50.99°), 2326 unique (Rint
=
ThiaH), 7.86 (d, J = 3.2 Hz, 1H, ThiaH), 7.56 – 7.53 (m, 2H, PhH), 0.0144, Rsigma = 0.0155) which were used in all calculations. The
7.41-7.35 (m, 2H, PhH), 7.23 (m, 1H, PhH). 13C NMR (101 MHz,
DMSO-d6): 122.29, 125.59, 125.86, 128.16, 137.29, 138.88,
144.00, 163.56, 176.28. Yellow rod-like crystals (0.35 × 0.08 ×
0.07 mm) of L1 were obtained from hot recrystallisation from
methanol. Crystal Data for C11H10N4S2 (M =262.35 g/mol):
final R1 was 0.0296 (I > 2σ(I)) and wR2 was 0.0812 (all data).
2.3 Complex synthesis
Unless stated otherwise, to a stirred solution of metal salt
monoclinic, space group P21/c (no. 14), a = 13.5767(10) Å, b = Fe(NO3)3·9H2O (24.0 mg, 0.06 mmol) or Co(BF4)2·6H2O (20.2 mg,
5.3420(4) Å, c = 17.5065(11) Å, β = 110.324(6)°, V = 0.06 mmol)) in methanol (20 mL), ligand (L1, L2 or L3) (0.12
1190.64(15) Å3, Z = 4, T = 100(2) K, μ(MoKα) = 0.428 mm-
mmol) was added. The resulting solution was stirred vigorously
2

for an hour at room temperature, before being subjected to monoclinic, space group P21/n (no. 14), a = 12.120(2) Å, b =
vapour diffusion of diethyl either, which resulted in very dark 14.421(3) Å, c = 15.666(3) Å, β = 103.54(3)°, V =
2662.1(10) Å3, Z = 4, T = 100.15 K, μ(MoKα) = 1.020 mm-1, Dcalc =
1.690 g/cm3, 15530 reflections measured (4.464° ≤ 2Θ ≤ 50.996°),
4948 unique (Rint = 0.0427, Rsigma = 0.0420) which were used in all
calculations. The final R1 was 0.0398 (I > 2σ(I)) and wR2 was
0.1000 (all data).
crystals:
2.3.1 [Fe(L1)2](NO3) - Yield: 30.4 mg (80%); HRMS ESI+ m/z:
577.9890 [Fe(L1)2 – NO3]+, C22H18N8S4Fe requires: 577.9881. IR:
ν= 3179, 3126, 3028, 3008, 1594, 1542, 1309, 1283, 1193, 1181
(NN), 1001 cm-1. UV/vis (MeOH) λmax = 402 nm, ε = 43,650 L mol-1
cm-1. Dark orange, plate like crystals of [Fe(L1)2](NO3)·H2O (0.48 × 2.3.5 [Co(L2)2](BF4) - Yield: 29.3 mg (71%); MS ESI+ m/z:
0.09 × 0.04 mm) were grown by diffusion of diethyl ether into the 609.0188 [Co(L1)2 – BF4]+, C24H22CoN8S4 requires: 609.0177; IR:
reaction solution. Crystal Data for C22H20FeN9O4S4 (M =658.56 ν= 3308, 3105, 3076, 3038, (NN), 987; λmax =402 nm; 1H NMR
g/mol): monoclinic, space group P21/n (no. 14), a = (400 MHz, DMSO-d6): δ 10.65 (s, 2H, NH), 9.01 (s, 2H, ImH), 7.72
12.0840(8) Å, b =
14.3302(10) Å, c =
15.8785(11) Å, β = (s, 2H, ThiaH), 7.58 (d, J = 8.0 Hz, 4H, PhH), 7.37 (dd[appt], J = 7.7
105.4500(10)°, V = 2650.3(3) Å3, Z = 4, T = 100.15 K, μ(MoKα) = Hz, 4H, PhH), 7.12 (t, J = 7.4 Hz, 2H, PhH), 2.22 (s, 6H, MethylH).
0.934 mm-1, Dcalc = 1.651 g/cm3, 15780 reflections measured Small, dark red, needle like crystals of [Co(L2)2](BF4)·Et2O (0.12 ×
(6.036° ≤ 2Θ ≤ 50.998°), 4914 unique (Rint = 0.0303, Rsigma
0.0266) which were used in all calculations. The final R1 was
0.0347 (I > 2σ(I)) and wR2 was 0.0950 (all data).
=
0.06 × 0.02 mm) were grown by diffusion of diethyl ether into the
reaction solution. Crystal Data for
C26H27BCoF4N8O0.5S4 (M =733.53 g/mol): monoclinic, space group
P21/c (no. 14), a = 10.9533(8) Å, b = 12.7844(9) Å, c =
23.1491(16) Å, β = 93.5960(10)°, V = 3235.2(4) Å3, Z = 4, T =
100.15 K, μ(MoKα) = 0.846 mm-1, Dcalc = 1.506 g/cm3, 30141
2.3.2 [Fe(L2)2](NO3) - Yield: 30.1 mg (76%); HRMS ESI+ m/z:
606.0204 [Fe(L2)2 – NO3]+, C24H22N8S4Fe requires: 606.0194. IR:
ν= 3026, 2953, 2920, 1604, 1592, 1335, 1291, 1207, 1182,
982.cm-1. UV/vis (MeOH) λmax = 406 nm, ε = 43,240 L mol-1 cm-1.
Dark orange, plate like crystals of [Fe(L2)2](NO3)·H2O (0.31 × 0.10
× 0.09 mm) were grown by diffusion of diethyl ether into the
reaction solution. Crystal Data for C24H24FeN9O4S4 (M =686.61
reflections measured (5.288° ≤ 2Θ ≤ 50°), 5678 unique (Rint
=
0.0575, Rsigma = 0.0312) which were used in all calculations. The
final R1 was 0.0511 (I > 2σ(I)) and wR2 was 0.1381 (all data).
2.3.6 [Co(L3)2](BF4) - To
a stirred solution of metal salt
g/mol): monoclinic, space group P21/c (no. 14), a = Co(BF4)2·6H2O (12.7 mg, 0.04 mmol)) in methanol (20 mL), ligand
9.0741(5) Å, b = 14.1019(10) Å, c = 22.4772(16) Å, β = (L3) (0.07 mmol) was added. Yield: 17.8 mg (70%); MS ESI+ m/z:
98.271(2)°, V = 2846.3(3) Å3, Z = 4, T = 100.15 K, μ(MoKα) = 0.873 609.0181 [Co(L1)2 – BF4]+, C24H22CoN8S4 requires 609.0177; IR: ν=
mm-1, Dcalc = 1.602 g/cm3, 16157 reflections measured (5.406° ≤ 3228, 2161, 1496, 1431, 1047, 750, 575 cm-1; λmax =402 nm; 1H
2Θ ≤ 50.998°), 5261 unique (Rint = 0.0724, Rsigma = 0.0750) which NMR (400 MHz, DMSO-d6): δ 10.74 – 9.90 (bs, 2H, NH), 8.08 (d, J =
were used in all calculations. The final R1 was 0.0528 (I > 2σ(I)) 3.5 Hz, 2H, ThiaH), 7.69 – 7.66 (m, 6H, PhH & ThiaH), 7.37
and wR2 was 0.1317 (all data).
(dd[appt], J = 7.8 Hz, 4H, PhH), 7.09 (t, J = 7.4 Hz, 2H, PhH), 2.95 (s,
2.3.3 [Fe(L3)2](NO3) - Yield: 30.1 mg (76%); HRMS ESI+ m/z:
606.0189 [Fe(L3)2 – NO3]+, C24H22N8S4Fe requires: 606.0194. IR:
ν= 3223, 3076, 1596, 1364, 1296, 1244, 1038, 690 cm-1 UV/vis
(MeOH) λmax = 397 nm, ε = 43,120 L mol-1 cm-1. Dark orange, plate
like crystals of [Fe(L3)2](NO3)· ¾H2O (0.19 × 0.12 × 0.05 mm)
were grown by diffusion of diethyl ether into the reaction
solution. Crystal Data for C24H23.5FeN9O3.75S4 (M =682.11 g/mol):
orthorhombic, space group Pna21 (no. 33), a = 14.0509(8) Å, b =
22.7382(13) Å, c = 8.6415(5) Å, V = 2760.9(3) Å3, Z = 4, T =
100.15 K, μ(MoKα) = 0.899 mm-1, Dcalc = 1.641 g/cm3, 11487
reflections measured (4.714° ≤ 2Θ ≤ 49.99°), 4787 unique (Rint
=
0.0483, Rsigma = 0.0829) which were used in all calculations. The
final R1 was 0.0687 (I > 2σ(I)) and wR2 was 0.1807 (all data),
twinned
data
refinement
scales for twin law –h, k, -l: 0.67(5) 0.33(5).
2.3.4 [Co(L1)2](BF4) - Yield: 27.0 mg (68%); MS ESI+ m/z:
580.9855 [Co(L1)2 – BF4]+, C22H18CoN8S4 requires: 580.9864; IR:
ν= 3328, 3137, 3078, 3038, 2973, 1593, 1526, 1417, 1398 1314,
1293, 1191, 1149, 1000 cm-1; 1H NMR (400 MHz, DMSO-d6): δ
10.60 (s, 2H, NH), 9.02 (s, 2H, ImH), 8.06 (d, J = 3.4 Hz, 2H, ThiaH),
7.68 (d, J = 3.4 Hz, 2H, ThiaH), 7.60 (d, J = 8.0 Hz, 4H, PhH), 7.39 –
7.34 (m, 4H, PhH), 7.12 (m, 2H, PhH). Small, dark red, plate like
crystals of [Co(L1)2](BF4)·½H2O (0.09 × 0.04 × 0.01 mm) were
grown by diffusion of diethyl ether into the reaction solution.
Crystal Data for C22H19BN8O0.5F4S4Co (M =677.43 g/mol):
Fig. 2 Molecular structures of L1 (top), L2 (middle) and L3 (bottom). Thermal
ellipsoids shown at 50% probability.
3

6H, MethylH). Despite repeated attempts, and under a variety of with respect to the angles formed between the thiazole
-
conditions only very poor quality dark orange block like crystals
(0.11 × 0.10 × 0.08 mm) were grown by diffusion of diethyl ether
into a methanol solution. The data quality was sufficiently poor
thiosemicarbazone mean-plane (4.7°) and the thiosemicarbazone
- phenyl mean-plane (14.3°). The thiourea moiety adopts an anti-
conformation and the imine bond adopts a trans configuration (i.e.
that no packing interactions are discussed and the molecular thiazole group and thiourea NH are trans). When examining the
structure serves to show the connectivity of the [Co(L3)2] cation long range packing two perpendicular planes of ligand run though
only. Crystal Data for C24H21CoN8S4 (M =608.66 g/mol):
the crystal along the b axis (Fig. S44, ESI), this is facilitated
orthorhombic, space group Pbca (no. 61), a = 8.4306(2) Å, b = through intermolecular hydrogen bonding [N(3)∙∙∙N(1)’
=
21.5049(6) Å, c = 33.7844(11) Å, V = 6125.1(3) Å3, Z = 8, T = 2.980(2) Å and <(N(3)-H(3X)···N(1)’)= 164°]. Small, dark orange,
100 K, μ(MoKα) = 0.860 mm-1, Dcalc = 1.320 g/cm3, 48295 rod-like crystals of L2 were obtained from hot recrystallisation
reflections measured (3.788° ≤ 2Θ ≤ 49.998°), 5383 unique (Rint
0.0609, Rsigma = 0.0380) which were used in all calculations. The group P212121, and contained one molecule in the asymmetric
final R1 was 0.0750 (I > 2σ(I)) and wR2 was 0.2076 (all data). The unit. The ligand conformation is very similar to that of L1, where it
=
from methanol and crystallised in the chiral orthorhombic space
structure was treated with a smtbx solvent mask in Olex2 to adopts a relatively flat structure with respect to the angles formed
-
remove the severely disordered BF4 counter anion and an between the thiazole - thiosemicarbazone mean-plane (11.4°) and
interstitial water molecule.
the thiosemicarbazone - phenyl mean-plane (5.8°). Again the
thiourea moiety adopts an anti-conformation and the imine bond
adopts a trans configuration as per L1. The long range packing
differs significantly to L1 as the intermolecular hydrogen bonding
3. Results and Discussion
Scheme 1 General synthesis of L1 – L3
Scheme 2 Complexation of ligands L1 – L3 with Fe(III) or Co(III).
in L2 [N(3)···N(1)’ = 3.025(5) Å and <(N(3)-H(3X)···N(1)’)= 158°]
3.1 Ligand synthesis and characterisation
results in
a helical hydrogen bonded 1D chain along the
Ligands L1 - L3 (Fig. 2) were synthesised by the same general
procedure (Scheme 1) using a stoichiometric reaction between
the thiazole carbonyl (2-thiazolecarboxaldehyde, 4-methyl-2-
crystallographic a-axis. Small pale yellow crystals of L3 were
grown from the slow evaporation of methanol. L3 crystallised in
the triclinic space group P-1 and contained one molecule in the
asymmetric unit. Like L1 and L2 the structure of L3 is again planar
with small mean-plane angles (<11°) between the three main
functional groups. The thiourea moiety adopts the anti-
conformation as per the previous systems. However, unlike L1 and
L2 the imine in L3 adopts a cis-configuration orientating the
thiazole nitrogen into a position to be involved in a second
intramolecular hydrogen bonding interaction between the second
thiourea NH group and the thiazole nitrogen atom [N(3)···N(1) =
2.698(2) Å and <(N(3)-H(3X)···N(1))= 136.2(2)°]. With both NH
donors involved in intramolecular hydrogen bonding, extension of
the structure via H-bonding does not occur, instead there are
weak off-set face to face π···π stacking interactions between the
thiazolecarboxaldehyde
or
2-acetylthiazole)
and
4-
phenylthiosemicarbazide in refluxing methanol or ethanol to yield
L1, L2 and L3 respectively. Following the reaction, concentration
of solvent resulted in pale orange/yellow solids in moderate
yields (48 – 69%). L1 – L3 were fully characterised using 1H-NMR,
13C-NMR, IR, UV/vis, mass spectrometry and X-ray
crystallography. All spectroscopic data was consistent with the
formation of the desired thiosemicarbazone ligands (see
supporting information). L1 and L3 match the literature data.30,31
Large pale yellow crystals of L1 were obtained by hot
recrystallisation from methanol. The ligand crystallised in the
monoclinic space group P21/c, with one molecule in the
asymmetric unit. The ligand adopts a relatively planar structure
Fig. 3 Stacked plot of 1H-NMR spectra of L1 (top) and [Co(L1)2](BF4) (bottom) recorded in DMSO-d6 highlighting shifted proton signals on complexation
4

A
B
C
Fig. 4 Molecular structures (top) of [Fe(L1)2](NO3)·H2O (A), [Fe(L2)2](NO3)·H2O (B), and [Fe(L3)2](NO3)·¾H2O (C) showing numbering scheme. Nitrate counter anion,
interstitial water molecules and hydrogen atoms are omitted for clarity – see ESI for additional figures of the molecular structures. Table of selected bond lengths and
angles (bottom) for all structurally characterised ligands and complexes. Σ values for complexes are also tabulated for structurally characterised Fe(III) and Co(III)
complexes.
-5
-1
thiazole and the phenyl rings on neighbouring molecules
[centroid···centroid = 3.74 Å, Fig. S45, ESI].
– S18, ESI). Spectra of L1-L3 (ca. 1x10 mol L in MeOH) displayed
similar spectral features with intense absorptions at λmax ~ 350
nm (ε 20,500 – 22,500 Lmol cm ). Absorption spectra of Fe(III)
complexes (ca. 1x10 mol L in MeOH) showed intense broad
charge-transfer absorptions at ~ 400 nm (ε ~43,000 Lmol cm )
accounting for the intense colour of the Fe(III) complexes. The
Fe(III) complexes appeared to be stable in solution over long
periods of time as the spectra collected some 4 weeks later were
-1
-1
3.2 Complex synthesis
-5
-1
-1
-1
Complexation reactions (Scheme) were carried out in methanol
between L1-L3 and Fe(NO3)3·9H2O and Co(BF4)2·6H2O using a 2:1
L:M ratio. In each case the addition of a methanolic solution of
metal salt to the methanolic ligand solution resulted in a dramatic
colour change from pale yellow to very dark orange/brown. The
dark solutions were stirred vigorously whilst open to the air at
room temperature for 1 h before being subjected to vapour
diffusion of diethyl ether. In all cases this gave very dark red to
orange crystals in reasonable yields (68-80%). The complexes all
adopt the general formula [M(L)2](anion)∙solvent with the metal
in the +3 oxidation state. The ligand binds through the thioenolate
form rather than the thioketo form giving a mono-negative charge
on the ligand.
1
unchanged. H-NMR spectra were collected of the three Co(III)
complexes in d6-DMSO (Fig. S2, S5, S8, ESI). In each case there
was a significantly shifted spectrum when compared to the
respective ligand spectrum (e.g. the imine protons display a ~0.6
ppm downfield shift) and loss of one NH resonance indicating
successful complexation (Fig. 3, S3, S6, S9, ESI). Again the
complexes exhibited significant solution stability, as spectra
collected 4 weeks apart were unchanged. The observed solution
stability indicates that these thiosemicarbazone complexes are
potentially ideal for development of supramolecular materials
and thus should be suitable for a variety of immobilisation
techniques where solution processability is required (e.g. gels,
Langmuir-Blodgett films and incorporation into polymers).
3.3 Infrared, Mass Spectrometry, NMR and UV/vis spectroscopy
Infrared spectroscopy provides a valuable tool for analysing these
thiosemicarbazone systems. On binding, the ligand undergoes a
tautomerism resulting in small spectral changes (C=S to C-S). The
comparison between ligands and complexes is shown in Fig S13 –
S15, ESI. The IR spectra of the complexes also show the expected
3.4 Crystallographic analysis of Fe3+ complexes
Crystals of [Fe(L1)2](NO3)·H2O, [Fe(L2)2](NO3)·H2O, and
[Fe(L3)2](NO3)· ¾H2O were obtained as large red/orange rods or
plates by diffusion of diethyl ether into methanolic solutions of
the complexes and the low temperature (100 K) structures
obtained (Fig. 4). [Fe(L1)2](NO3)·H2O crystallised in the
monoclinic spacegroup P21/c, [Fe(L2)2](NO3)·H2O crystallised in
the monoclinic space group P21/n and [Fe(L3)2](NO3)·¾H2O
crystallised in the orthorhombic space group Pna21. In all cases
the asymmetric unit contained one complete molecule and one
-
-
signals for the NO3 and BF4 anions in the Fe(III) and Co(III)
complexes respectively. High-resolution mass spectra of all
ligands and complexes were collected and showed the expected
peaks and isotopic distributions for all ligands and complexes
(Fig. S19 – S27, ESI). Electronic spectra of ligands and iron
complexes were obtained in MeOH and in the solid state (Fig S16
5

Fig. 5 Packing diagrams of [Fe(L1)2](NO3)·H2O (top) showing spiralled layer
formation and [Fe(L2)2](NO3)·H2O showing both the orientation of the packing
along the crystallographic c-axis (bottom).
interstitial water molecule (either full or ¾ occupancy). The
general structure of each complex is similar where the Fe(III)
centre adopts a distorted octahedral geometry with an S2N4
coordination sphere. Bond lengths and angles are consistent with
low-spin Fe(III) and are summarised in Figure 4. Analysis of the
distortion parameter, Σ (sum of the deviation of the cis bond
angles from 90°),18,21,44,45 indicated relatively small distortion
from purely octahedral geometry (ranging from 68.7° to 71.5°).
The data also reaffirms the IR spectroscopic interpretation of
changes in bond lengths for the C=S and C-N bonds (Fig. 4).
Packing in the solid state is an important area of consideration for
potential SCO systems as intermolecular interactions can increase
communication between neighbouring molecules and therefore
Fig. 6 Variable temperature EPR of [Fe(L1)2](NO3)·H2O (top),
[Fe(L2)2](NO3)·H2O (middle) and [Fe(L3)2](NO3)· ¾H2O (bottom).
enhance the cooperative nature of the magnetism. In these [N(21)···O(100) = 2.822(4) Å and <(N(21)-H(21)···O(100))= 171°]
systems the ligands have many functional groups capable of and also to the interstitial water [O(200)···O(100)’ = 2.797(5) Å
extending the structure through supramolecular interactions (e.g.
H-bonding, π···π stacking, anion···π and CH···π interactions)
making analysis of the packing important. [Fe(L1)2](NO3)·H2O
and <(O(200)-H(20A) ···O(100)’)= 172°]. This in turn acts as the
acceptor to the other thioamide NH [N(1)···O(200)’ = 2.885(5) Å
and <(N(1)-H(1)···O(200))= 174°]. The end result is the linking of
displays hydrogen bonding interactions between thioamide NH molecules through H-bonding interactions to the nitrate and
groups on neighbouring complexes (N(4)’ and N(24)) and a interstitial water molecules giving rise to a complex H-bonding
nitrate counter anion [N(4)’···O(102) = 2.877(3) Å and <(N(4)’- network (Fig. 5). Packing in [Fe(L3)2](NO3)·¾H2O is similar to that
H(4X)’···O(102))= 172°; N(24)···O(102) 2.845(3) and of [Fe(L2)2](NO3)·H2O. Again, the nitrate anion acts as an acceptor
<(N(24)-H(24X)···O(102))= 160°] where the NO3- acts as a bridge
in a hydrogen bond to one thioamide NH [N(1)···O(102)’ =
=
Å
between two complex molecules (Fig S44, ESI). The interstitial 2.929(15) Å and <(N(1)-H(1)···O(102)’)= 151°] and also to the
water molecule further bridges the nitrate anion to a third interstitial water [O(200)···O(102)’ = 2.888(16) Å and <(O(200)-
molecule by acting as a hydrogen bond donor to a nitrate oxygen H(20B) ···O(102)’)= 169°]. This in turn acts as the acceptor to the
atom (O(100)) and the thioenolate nitrogen atom (N(23)’) on a other thioamide NH [N(21)···O(200) = 3.008(15) Å and <(N(21)-
neighbouring molecule [O(200)···O(100) = 2.856(3)
Å
and H(21)···O(200))= 172°]. Overall, the packing in these Fe(III)
<(O(200)-H(20Y) ···O(100))= 176°; O(200)···N(23)” = 2.924(3) Å systems is complex and extensive, and there are multiple
and <(O(200)-H(20Y)···N(23)”)= 174°]. The NH and OH hydrogen supramolecular connections that link neighbouring molecules
within the crystal structure (Fig. S46, ESI).
bonding interactions described above link neighbouring
complexes into a 2D hydrogen bonded network (Fig. 5). Packing
in [Fe(L2)2](NO3)·H2O is slightly different in that the nitrate
counter anion does not act as a bridge between two thioamide NH
groups on neighbouring complex molecules. Instead the nitrate
3.5 Crystallographic analysis of Co3+ complexes
Crystals of [Co(L1)2](BF4)·H2O, [Co(L2)2](BF4)·Et2O, and
anion acts as an acceptor in a hydrogen bond to one thioamide NH [Co(L3)2](BF4) were also obtained as red plate-like crystals by
6

diffusion of diethyl ether into methanolic solutions of the H(10Y) ···F(2))= 138°; O(1)···N(23)” = 2.861(5) Å and <(O(1)-
complexes and the Low temperature (100 K) structures studied. H(10X)···N(23)”)= 165°]. The NH and OH hydrogen bonding
[Co(L1)2](BF4)·H2O crystallised in the monoclinic space group interactions described above link neighbouring complexes into a
P21/n, [Co(L2)2](BF4)·Et2O in the monoclinic space group P21/c 2D hydrogen bonded network. Packing in [Co(L2)2](BF4)·H2O is
and [Co(L3)2](BF4) in the orthorhombic space group Pbca. The slightly different in that the tetrafluoroborate counter anion does
general structure of each complex is similar to the Fe(III) systems not act as a bridge between two thioamide NH groups on
where the Co(III) centre adopts a distorted octahedral geometry neighbouring complex molecules.
with a S2N4 coordination sphere. In the Co(III) systems the complexes interact directly with each other through the
coordination geometries are closer to pure octahedral than the thioamide NH and an adjacent thioamide S [N(24)···S(2)’
Fe(III) analogues (distortion parameter Σ range = 48.5 – 53.6°). 3.428(3) Å and <(N(24)-H(24X)···S(2)’)= 159°] and the thioamide
Packing interactions are also somewhat similar to the Fe(III) NH with the tetrafluoroborate counter anion [N(4)···F(1)
Instead neighbouring
=
=
2.883(4) Å and <(N(4)-H(4) ···F(1))= 145°].
versions with the exception of [Co(L2)2](BF4)·Et2O which has a
disordered partial occupancy Et2O molecule within the crystal
lattice.
[Co(L1)2](NO3)·H2O displays hydrogen bonding
interactions between the thioamide NH groups on neighbouring
complexes (N(4)’ and N(24)) and a tetrafluoroborate counter
anion [N(4)’···F(4) = 2.896(3) Å and <(N(4)’-H(4X)’···F(4))= 171°;
N(24)···F(4) = 2.882(4) Å and <(N(24)-H(24X)···F(4))= 161°]
3.6 Electron Paramagnetic Resonance and Magnetism
Variable temperature X-band EPR also confirmed the
predominantly low spin nature of these complexes.
Measurements on all complexes, between 283 and 373 K, exhibit a
g factor of ca. 2.1, indicative of low spin Fe(III) complexes (Fig. 6).
Variable temperature magnetic susceptibility measurements were
obtained for crystalline samples of [Fe(L1)2](NO3)·H2O,
[Fe(L2)2](NO3)·H2O, and [Fe(L3)2](NO3)·¾H2O between 10 and
400 K in an applied field of 1000 Oe. All three Fe(III) complexes
exhibit very similar properties with a static χMT value of 0.5 cm3
mol-1 K between 10 and 300 K (Fig. 7). The S = 1/2 low spin
assignment at low temperatures is in accordance with the bond
lengths of approximately 2 Å for the Fe-N donors.
-
where the BF4 acts as a bridge between two complex molecules
4. Conclusions
We have reported on the synthesis and characterisation of
six new Fe(III) and Co(III) complexes prepared from novel
thiosemicarbazone ligands. Variable temperature magnetic
measurements and EPR spectra of the Fe(III) systems
showed that they adopted a low spin configuration from 10 –
300 K. The complexes displayed significant solution stability,
as assessed through electronic spectra for Fe(III) complexes
and NMR spectra for Co(III) complexes run four weeks apart.
The solid-state structures displayed many intermolecular
interactions linking the complexes into intricate arrays. The
combination of significant structure extension through
supramolecular interactions and solution stability is ideal for
the development of supramolecular materials as the systems
should be suitable for a variety of immobilisation techniques
where solution processability is required
(e.g. gels,
Langmuir-Blodgett films and incorporation into polymers).
We are currently investigating the development of such
systems through incorporation of structure directing
substituents into the ligands. Additionally, the ligand family
presented herein is similar to known SCO ligands, thus it
represents an upper limit to ligand field strength, laying the
foundation for tailored design of these ligands for highly
processable solution-stable SCO species.
electron-withdrawing groups to the thiazole ring is expected
to favourably alter the ligand field strength.
Addition of
Fig 7 Plots of ꢀMT vs. T for [Fe(L1)2](NO3)·H2O (top), [Fe(L2)2](NO3)·H2O
(middle) and [Fe(L3)2](NO3)· ¾H2O (bottom).
(Fig S41, ESI). The interstitial water molecule further bridges the
tetrafluoroborate anion to a third complex molecule by acting as a
hydrogen bond donor to two tetrafluoroborate fluorine atoms
(F(1) & F(2)) and the thioenolate nitrogen atom (N(23)’) on a
neighbouring molecule [O(1)···F(1) = 3.001(5) Å and <(O(1)-
H(10Y) ···F(1))= 160°;[O(1)···F(2) = 3.169(6) Å and <(O(1)-
Acknowledgements
The authors are grateful to the University of Southampton
and University College Dublin for support of this work. JAK
thanks the EPSRC for funding through grant references
7

19 J. A. Kitchen, A. Noble, C. D. Brandt, B. Moubaraki, K. S. Murray
and S. Brooker, Inorg. Chem., 2008, 47, 9450–9458.
20 J. A. Kitchen, N. G. White, M. Boyd, B. Moubaraki, K. S. Murray,
P. D. W. Boyd and S. Brooker, Inorg. Chem., 2009, 48, 6670–
6679.
21 J. A. Kitchen, J. Olguín, R. Kulmaczewski, N. G. White, V. A.
Milway, G. N. L. Jameson, J. L. Tallon and S. Brooker, Inorg.
Chem., 2013, 52, 11185–11199.
EP/K039466/1 and EP/K014382/1. ABC thanks the
Leverhulme Trust for the award of Study Abroad
a
Studentship (SAS2016-38). GGM would like to thank Science
Foundation Ireland for Investigator Project Award
12/IP/1703, The National University of Ireland and the
Cultural Service of the French Embassy in Ireland for
scholarships (to A.J.F) and the Irish Higher Education
Authority for funding for a SQUID magnetometer.
22 J. A. Kitchen, G. N. L. Jameson, J. L. Tallon and S. Brooker, Chem.
Commun., 2010, 46, 3200–3202.
23 N. G. White, H. L. C. Feltham, C. Gandolfi, M. Albrecht and S.
Brooker, Dalton Trans., 2010, 39, 3751–3758.
24 M. Cavallini, Phys. Chem. Chem. Phys., 2012, 14, 11867–11876.
25 J. A. Kitchen, N. Zhang, A. B. Carter, A. J. Fitzpatrick and G. G.
Morgan, J. Coord. Chem., 2016, 69, 2024–2037.
26 A. J. Fitzpatrick, P. N. Martinho, B. J. Gildea, J. D. Holbrey and G.
G. Morgan, Eur. J. Inorg. Chem., 2016, 2025–2029.
27 P. N. Martinho, C. J. Harding, H. Müller-Bunz, M. Albrecht and G.
G. Morgan, Eur. J. Inorg. Chem., 2010, 675–679.
28 E. N. W. Howe, N. Busschaert, X. Wu, S. N. Berry, J. Ho, M. E.
Light, D. D. Czech, H. A. Klein, J. A. Kitchen and P. A. Gale, J. Am.
Chem. Soc., 2016, 138, 8301–8308.
29 B. Ghosh, P. Adak, S. Naskar, B. Pakhira, P. Mitra, R. Dinda, S. K.
Chattopadhyay, Inorg. Chim. Acta., 2017, 459, 1–14.
30 N. A. Ryabova, V. I. Ponomarev, V. V. Zelentsov, V. I. Shipilov
and L. O. Atovmyan, J. Struct. Chem., 1981, 22, 234–238.
31 J. R. Dilworth and R. Hueting, Inorg. Chim. Acta., 2012, 389, 3–
15.
References
1
J. P. Byrne, J. A. Kitchen and T. Gunnlaugsson, Chem. Soc. Rev.
Chem., 2014, 43, 5302–5325.
2
J. E. M. Lewis, E. L. Gavey, S. A. Cameron and J. D. Crowley,
Chem. Sci., 2012, 3, 778–784.
3
4
D. J. Wales and J. A. Kitchen, Chem. Cent. J., 2016, 10, 72.
A. Ferguson, R. W. Staniland, C. M. Fitchett, M. A. Squire, B. E.
Williamson and P. E. Kruger, Dalton Trans., 2014, 43, 14550–
14553.
5
6
S. Shanmugaraja, C. Dabadie, K. Byrne, A. J. Savyasachi, D.
Umadevi, W. Schmitt, J. A. Kitchen and T. Gunnlaugsson, Chem.
Sci., 2017, 8, 1535-1546.
C. Bartual-Murgui, A. Akou, C. Thibault, G. Molnár, C. Vieu, L.
Salmon and A. Bousseksou, J. Mater. Chem. C, 2015, 3, 1277–
1285.
7
8
9
S. Ji, W. Wu, W. Wu, P. Song, K. Han, Z. Wang, S. Liu, H. Guo and
J. Zhao, J. Mater. Chem., 2010, 20, 1953–1963.
V. W-W. Yam and K. M-C. Wong, Chem. Commun., 2011, 47,
11579–11592.
M. Galli, J. E. M. Lewis and S. M. Goldup, Angew. Chem. Int. Ed.,
2015, 54, 13545–13549.
32 N. C. Saha, A. Saha, R. J. Butcher, S. Chaudhuri and N. Saha,
Inorg. Chim. Acta, 2002, 339, 348–354.
33 M. M. M. Raposo, B. García-Acosta, T. Ábalos, P. Calero, R.
Martínez-Máñez, J. V. Ros-Lis and J. Soto, J. Org. Chem., 2010,
75, 2922–2933.
34 R. Venkatraman, H. Ameera, L. Sitole, E. Ellis, F. R. Fronczek
and E. J. Valente, J. Chem. Crystallogr., 2009, 39, 711–718.
35 R. Venkatraman, M. A. Hossain and F. R. Fronczek, Acta
Crystallogr. Sect. E Struct. Rep. Online, 2010, 66, 541–542.
36 R. Venkatraman, D. S. Samuel, Z. Arslan, M. A. Hossain and F. R.
Fronczek, Acta Crystallogr. Sect. E Struct. Rep. Online, 2013,
69, 246–247.
37 S. R. Arumugam, S. S. R. Dasary, R. Venkatraman, H. Yu and F. R.
Fronczek, Acta Crystallogr. Sect. E Struct. Rep. Online, 2011,
67, 1409–1410.
38 S. S. R. Dasary, S. R. Arumugam, H. Yu, R. Venkatraman and F. R.
Fronczek, Acta Crystallogr. Sect. E Struct. Rep. Online, 2011,
67, 816–817.
39 S. J. Coles and P. A. Gale, Chem. Sci., 2012, 3, 683–689.
40 CrystalClear-SM Expert 3.1, (Rigaku, 2012).
41 CrysAlisPro 38.41, (Rigaku Oxford Diffraction, 2015).
42 G. M. Sheldrick, Acta Crystallogr. A, 2008, 64, 112–122.
43 O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard and
H. Puschmann, J. Appl. Crystallogr., 2009, 42, 339–341.
44 R. G. Miller and S. Brooker, Inorg. Chem., 2015, 54, 5398–5409.
45 J. Nelson, V. McKee, G. Morgan, Prog. Inorg. Chem. 1998, 47,
167–317
.
10 D. J. Harding, W. Phonsri, P. Harding, I. A. Gass, K. S. Murray, B.
Moubaraki, J. D. Cashion, L. Liu and S. G. Telfer, Chem.
Commun., 2013, 49, 6340–6342.
11 M. J. Murphy, T. D. Keene, J. R. Price, D. M. D’Alessandro and C.
J. Kepert, Aust. J. Chem., 2014, 67, 1607–1611.
12 R. E. Powell, C. H. Schwalbe, G. J. Tizzard and P. J. van
Koningsbruggen, Acta Crystallogr. Sect. C Struct. Chem., 2014,
70, 595–598.
13 S. Floquet, E. Rivière, K. Boukheddaden, D. Morineau and M.-L.
Boillot, Polyhedron, 2014, 80, 60–68.
14 Z.-Y. Li, J.-W. Dai, Y. Shiota, K. Yoshizawa, S. Kanegawa and O.
Sato, Chem. Eur. J., 2013, 19, 12948–12952.
15 Z.-Y. Li, J.-W. Dai, K. J. Gagnon, H.-L. Cai, T. Yamamoto, Y.
Einaga, H.-H. Zhao, S. Kanegawa, O. Sato, K. R. Dunbar and R.-G.
Xiong, Dalton Trans., 2013, 42, 14685–14688.
16 E. W. Y. Tido, C. Faulmann, R. Roswanda, A. Meetsma and P. J.
van Koningsbruggen, Dalton Trans., 2010, 39, 1643–1651.
17 S. Floquet, M. C. Muñoz, R. Guillot, E. Rivière, G. Blain, J.-A. Réal
and M.-L. Boillot, Inorg. Chim. Acta, 2009, 362, 56–64.
18 J. A. Kitchen, N. G. White, G. N. L. Jameson, J. L. Tallon and S.
Brooker, Inorg. Chem., 2011, 50, 4586–4597.
8

Highlights
•
New thiosemicarbazone-based Fe(III) and Co(III) complexes were prepared and structurally
characterised
•
•
The Fe(III) complexes adopt the low-spin configuration
The complexes display good solution stability
9

The synthesis, characterisation and structural properties of
novel Fe(III) and Co(III) coordination complexes
featuring thiosemicarbazone-based ligands are reported.