Nickel(IV) dithiocarbamato complexes of the [Ni(ndtc)3]X type: X-ray structure of [Ni(hmidtc)3][FeCl4]

Article abstract of DOI:10.1016/j.poly.2011.08.022

A series of fourteen octahedral nickel(IV) dithiocarbamato complexes of the general formula [Ni(ndtc)₃]X·yH₂O {ndtc stands for the appropriate dithiocarbamate anion, X stands for ClO₄^- (1-8; y = 0) or [FeCl₄]^- (9-14; y = 0 for 9-12, 1 for 13 and 0.5 for 14} was prepared by the oxidation of the corresponding nickel(II) complexes, i.e. [Ni(ndtc)₂], with NOClO₄ or FeCl ₃. The complexes, involving a high-valent Ni^IVS ₆ core, were characterized by elemental analysis (C, H, N, Cl and Ni), UV-Vis and FTIR spectroscopy, thermal analysis and magnetochemical and conductivity measurements. The X-ray structure of [Ni(hmidtc) ₃][FeCl₄] (9) was determined {it consists of covalently discrete complex [Ni(hmidtc)₃]⁺ cations and [FeCl ₄]^- anions} and this revealed slightly distorted octahedral and tetrahedral geometries within the complex cations, and anions, respectively. The Ni(IV) atom is six-coordinated by three bidentate S-donor hexamethyleneiminedithiocarbamate anions (hmidtc), with Ni-S bond lengths ranging from 2.2597(5) to 2.2652(5) , while the shortest Ni...Cl and Ni...Fe distances equal 4.1043(12), and 6.2862(6) , respectively. Moreover, the formal oxidation state of iron in [FeCl₄]^- as well as the coordination geometry in its vicinity was also proved by ⁵⁷Fe Moessbauer spectroscopy in the case of 9.

Full text of DOI:10.1016/j.poly.2011.08.022

Polyhedron 30 (2011) 2795–2800
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Nickel(IV) dithiocarbamato complexes of the [Ni(ndtc)3]X type: X-ray structure
of [Ni(hmidtc)3][FeCl4]
a
b
a
b,
⇑
ˇ
ˇ
Richard Pastorek , Pavel Štarha , Tomáš Peterek , Zdenek Trávnícek
a Department of Inorganic Chemistry, Faculty of Science, Palacky´ University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
b Regional Centre of Advanced Technologies and Materials, Department of Inorganic Chemistry, Faculty of Science, Palacky´ University, 17. listopadu 12,
CZ-771 46 Olomouc, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 June 2011
A
series of fourteen octahedral nickel(IV) dithiocarbamato complexes of the general formula
ꢁ
[Ni(ndtc)3]XꢀyH2O {ndtc stands for the appropriate dithiocarbamate anion, X stands for ClO4 (1–8;
y = 0) or [FeCl4]ꢁ (9–14; y = 0 for 9–12, 1 for 13 and 0.5 for 14} was prepared by the oxidation of the cor-
responding nickel(II) complexes, i.e. [Ni(ndtc)2], with NOClO4 or FeCl3. The complexes, involving a high-
valent NiIVS6 core, were characterized by elemental analysis (C, H, N, Cl and Ni), UV–Vis and FTIR spec-
troscopy, thermal analysis and magnetochemical and conductivity measurements. The X-ray structure
of [Ni(hmidtc)3][FeCl4] (9) was determined {it consists of covalently discrete complex [Ni(hmidtc)3]+ cat-
ions and [FeCl4]ꢁ anions} and this revealed slightly distorted octahedral and tetrahedral geometries
within the complex cations, and anions, respectively. The Ni(IV) atom is six-coordinated by three biden-
tate S-donor hexamethyleneiminedithiocarbamate anions (hmidtc), with Ni–S bond lengths ranging from
2.2597(5) to 2.2652(5) Å, while the shortest NiꢀꢀꢀCl and NiꢀꢀꢀFe distances equal 4.1043(12), and
6.2862(6) Å, respectively. Moreover, the formal oxidation state of iron in [FeCl4]ꢁ as well as the coordi-
nation geometry in its vicinity was also proved by 57Fe Mössbauer spectroscopy in the case of 9.
Ó 2011 Elsevier Ltd. All rights reserved.
Accepted 7 August 2011
Available online 5 September 2011
Keywords:
Nickel(IV) complexes
Dithiocarbamate
X-ray structure
Spectroscopy
1. Introduction
of the previously reported [Ni(but2dtc)3]Br revealed a distorted
octahedral geometry, and moreover it was found that the com-
Compounds involving nickel in its higher formal oxidation
states, such as Ni(III)/Ni(IV), play an important role in many
branches of industry (e.g., several representatives of nickel(IV)
complexes bearing three bidentate-coordinated dithiocarbamate
anions were used as a part of mineral or synthetic oil-based lubri-
cants or lubricant concentrates [1]) and in biological systems (e.g.,
methanogenic bacteria [2]). Nevertheless, a systematic literature
search of worldwide chemical (e.g., Web of Science) and crystal-
lographic (e.g., Cambridge Structural Database) databases re-
vealed few works dealing with nickel(IV) complexes (see e.g.,
[3–5]). In particular, although nickel(IV) complexes involving
three bidentate-coordinated dithiocarbamate-based S-donor li-
gands (which is the subject of this work) have been known for
more than 40 years, the total number of these compounds is
not very large, as it is briefly reviewed below. The first of these
compounds, a group of [Ni(ndtc)3]Br complexes, were prepared
in 1969 by the oxidation of the appropriate [Ni(ndtc)2] complex
by bromine in CCl4 {ndtc stands for N,N-diethyldithiocarbamate
(et2dtc), N,N-dibutyldithiocarbamate (but2dtc) and N,N-dib-
enzyldithiocarbamate (bz2dtc)} [6]. The X-ray molecular structure
pound, and its analogs of the compositions [Ni(bz2dtc)3]Br, [Ni
(but2dtc)3](BF3Br), [Ni(but2dtc)3]NO3 and [Ni(et2dtc)3]Br, behave
as diamagnetics, thus proving that they have the oxidation state
+IV [7,8]. Hendrickson et al., followed the synthetic strategies
described in the above-mentioned papers and prepared several
new [Ni(ndtc)3]+ complexes, specifically [Ni(et2dtc)3]BF4 and [Ni
(bu2dtc)3]BF4 [9]. Golding et al. used iron(III) perchlorate and
iron(III) chloride for the oxidation of nickel(II) dithiocarbamato
complexes to the nickel(IV) analogs, preparing [Ni(et2dtc)3]ClO4,
[Ni(et2dtc)3][FeCl4], [Ni(etphdtc)3]ClO4 and [Ni(pipdtc)3][FeCl4],
where etphdtc = ethylphenyldithiocarbamate and pipdtc = piper-
idinedithiocarbamate [10]. The complexes [Ni(et2dtc)3]PF6 and
[Ni(but2dtc)3]PF6 were used for the preparation of [Ni
(R–CN)2(et2dtc)2]PF6, where R stands for iso-propyl, tert-butyl,
p-chlorophenyl, methyldiphenylphosphine or ½ of 1,2-bis(diphen
ylphosphino)ethane [11]. Larionov et al., reported the preparation
and characterization of the octahedral and diamagnetic [Ni
(ndtc)3]Br and [Ni(ndtc)3]I5 (ndtc symbolizes N,N-dipropyldithioc-
arbamate and N,N-diisopropyldithiocarbamate anions) [12]. Other
nickel(IV) dithiocarbamato complexes, specifically [Ni(pipdtc)3]-
ClO4, [Ni(pipdtc)3]NO3, [Ni(plddtc)3]NO3 and [Ni(plddtc)3][FeCl4],
were also prepared and described by Pastorek et al. (plddtc stands
for pyrrolidindithiocarbamate) [13,14]. The X-ray structure of
⇑
Corresponding author. Tel.: +420 585 634 352; fax: +420 585 634 954.
ˇ
E-mail address: zdenek.travnicek@upol.cz (Z. Trávnícek).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.08.022

2796
R. Pastorek et al. / Polyhedron 30 (2011) 2795–2800
Table 1
[Ni(et2dtc)3]PCNP was determined by a single crystal X-ray anal-
ysis as the second crystallographically studied nickel(IV) dithio-
carbamato complex of the NiS6 donor set so far;
PCNP = pentacyanopropenide [15]. The heterobimetallic nickel(IV)
dithiocarbamato complex with a ferrocenyl group bound to each
Crystal data and structure refinement for [Ni(hmidtc)3][FeCl4] (9).
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system, space group
Unit cell dimensions
a = b (Å)
C21H36N3Cl4FeNiS6
779.25
115(2)
0.71073
of three dithiocarbamato moieties, having
a composition of
ꢀ
Rhombohedral, R3
[Ni(etferdtc)3][BF4] with etferdtc = N,N-ethyl-ferrocenecarboxalde-
hydeethylimine dithiocarbamate anion, was prepared using elec-
tro-oxidation of the appropriate nickel(II) complex, i.e.
[Ni(etferdtc)2] [16].
15.7605(3)
22.5351(8)
90.00
120.00
4847.6(2)
6, 1.602
1.768
c (Å)
a
c
= b (°)
(°)
V (Å3)
Z, Dcalc (g cmꢁ3
)
2. Experimental
Absorption coefficient (mmꢁ1
Crystal size (mm)
)
0.40 ꢂ 0.35 ꢂ 0.25
2.1. Starting materials
F (000)
2406
h range for data collection (°)
Index ranges (h, k, l)
3.12 6 h 6 24.98
ꢁ18 6 h 6 18
ꢁ18 6 k 6 18
ꢁ26 6 l 6 19
12181/1888 (0.0138)
1888/0/128
1.112
R1 = 0.0250, wR2 = 0.0637
R1 = 0.0270, wR2 = 0.0644
0.577, ꢁ0.542
All chemicals and solvents used in this work were purchased
from Sigma–Aldrich Co., Lachema Co., and Fluka Co., and they were
used as received. The starting Ni(II) complexes, i.e. [Ni(hmidtc)2] (a),
[Ni(indtc)2] (b), [Ni(bzppzdtc)2] (c), [Ni(bz2dtc)2] (d), [Ni(pe2dtc)2]
(e), [Ni(bziprdtc)2] (f), [Ni(bzmedtc)2] (g) and [Ni(chetdtc)2] (h) were
prepared according to a previously described procedure [17]:
hmidtc, hexamethyleneiminedithiocarbamate anion; indtc, indo-
linedithiocarbamate anion; bzppzdtc, benzylpiperazinedithiocarba-
mate anion; pe2dtc, N,N-dipentyldithiocarbamate anion; bziprdtc,
N,N-benzyl-isopropyldithiocarbamate anion; bzmedtc, N,N-benzyl-
methyldithiocarbamate anion; chetdtc, N,N-cyclohexyl-ethyldi-
thiocarbamate anion.
Reflections collected/unique (Rint
Data/restraints/parameters
Goodness-of-fit on F2
)
Final R indices [I > 2
r
(I)]
R indices (all data)
Largest peak and hole (e Åꢁ3
)
[18]. The molar conductivity of 10ꢁ3 M acetone solutions was mea-
sured by an LF 330/SET conductometer (WTW GmbH) at 25 °C.
Electronic absorption spectra of 1.67 ꢂ 10ꢁ4 M DMF solutions of
8–14 and solid state (diffuse–reflectance, nujol technique) spectra
of 1–14 were recorded on a Specord M40 device. FTIR spectra
(450–4000 cmꢁ1 region) were recorded on a Perkin–Elmer Spec-
trum one FTIR spectrometer using the KBr technique. Simultaneous
thermogravimetric (TG) and differential thermal (DTA) analysis
was performed by an Exstar TG/DTA 6200 (Seiko Instruments
Inc.) in a dynamic air atmosphere (100 mL minꢁ1) from laboratory
temperature to 1050 °C with a 2.5 °C minꢁ1 heating rate. Complex
13 was also studied by simultaneous thermogravimetry and differ-
ential scanning calorimetry (DSC) from laboratory temperature to
800 °C (5.0 °C minꢁ1 gradient) in a dynamic argon atmosphere,
which was carried out by a STA 449 C Jupiter (Netzsch) coupled
with a quadrupole mass spectrometer QMS 403 Aëolos (Netzsch).
The transmission 57Fe Mössbauer spectrum was measured at
300 K in zero applied magnetic field using a spectrometer working
in a constant acceleration mode with a 57Co(Rh) radioactive
source; iron foil was used as a calibration standard. X-ray powder
diffraction experiments were performed with a PANalytical X’Pert
2.2. Syntheses of nickel(IV) complexes (1–14)
2.2.1. [Ni(ndtc)3]ClO4 (1–8)
2.5 mmol of pulverized [Ni(ndtc)2] (a–h) was dissolved in 20 mL
of CHCl3 and NOClO4 (3.2 mmol), as an oxidant, was added to this
solution with constant stirring. The reaction mixture was stirred
with charcoal at room temperature for 2–3 h, and consequently fil-
tered. 50 mL of diethyl ether (or hexane) were added to the filtrate
which led to the formation of a brown (or dark brown) precipitate.
The product was filtered off, washed with diethyl ether (or hexane)
and dried at 40 °C under an infrared lamp. Caution: the prepared
compounds need to be handled carefully because the some of 1 ex-
ploded on the fritted funnel while it was being scraped off.
2.2.2. [Ni(ndtc)3][FeCl4]ꢀyH2O (9–14)
FeCl3 (2 mmol) was added to
a solution of the starting
[Ni(ndtc)2] complex (a, b, d, f–h; 1 mmol) in 20 mL of CHCl3. The
reaction mixture was stirred for 1–5 h, and after that it was filtered
(together with charcoal). Diethyl ether, hexane or a mixture of ben-
zene and diethyl ether (1:1, v/v) was added to the filtrate. A brown
or dark brown product precipitated and it was filtered off, washed
(diethyl ether) and dried at 40 °C (infrared lamp). In the case of 9,
dark brown crystals formed in the benzene/diethyl ether mixture
(1:1, v/v), some of which were found to be suitable for a single
crystal X-ray analysis.
PRO instrument (CoK
a radiation) equipped with an X’Celerator
detector. Samples were placed on a zero-background Si slide and
scanned in the 2h range of 5–90° in steps of 0.017°. Evaluation
was made using HighScore Plus software and a PDF-4 database.
2.4. Single crystal X-ray analysis of [Ni(hmidtc)3][FeCl4] (9)
The single crystal X-ray analysis of a selected crystal of 9 was
2.3. Physical measurements
collected on an Xcalibur™2 diffractometer (Oxford Diffraction
Ltd.) with a Sapphire2 CCD detector and with MoK
a radiation
Elemental analyses (C, H, N) were performed on a Flash 2000
CHNS Elemental Analyzer (Thermo Fisher Scientific). Chlorine con-
tents were determined using the Schöniger method and the nickel
content was determined by chelatometric titration with murexide
as an indicator. The measurements of the room temperature mag-
netic susceptibilities were performed using the Faraday method
with a laboratory designed instrument with a Sartorius 4434 MP-
8 microbalance; Co[Hg(NCS)4] was used as a calibrant and the cor-
rection for diamagnetism was performed using Pascal constants
(Monochromator Enhance, Oxford Diffraction Ltd.). Data collection
and reduction were performed using CrysAlis software [19]. The
same software was used for data correction for an absorption effect
by empirical absorption correction using spherical harmonics,
implemented in the SCALE3 ABSPACK scaling algorithm. The struc-
ture was solved by direct methods using SHELXS-97 and refined on F2
using the full-matrix least-squares procedure (SHELXL-97) [20]. Non-
hydrogen atoms were refined anisotropically and hydrogen atoms
were located in a difference map and refined by using the riding

R. Pastorek et al. / Polyhedron 30 (2011) 2795–2800
2797
structure of these compounds. The latter situation corresponds with
the presumption of five unpaired electrons (S = 5/2) of the Fe(III)
atom in [FeCl4]ꢁ and a diamagnetic nickel(IV) atom in the structure
of the [Ni(ndtc)3][FeCl4] complexes (9–14).
3.2. Single crystal X-ray analysis of [Ni(hmidtc)3][FeCl4] (9)
Complex 9 was prepared in the crystalline form and some crys-
tals were found to be suitable for a crystallographic study. The
molecular structure of 9 is depicted in Fig. 1. The crystal data
and structure refinements are given in Table 1, while Table 4 sum-
marizes selected bond lengths and angles.
The molecular structure of the ionic-pair complex 9 involves the
[Ni(hmidtc)3]+ cation and [FeCl4]ꢁ anion (Fig. 1). The Ni(IV) atom of
[Ni(hmidtc)3]+ is hexacoordinated by three bidentate S-donor li-
gands (hmidtc anions) arranged in a slightly distorted octahedral
geometry around the metal center. A comparison of the parameters
of 9 with both nickel(IV) complexes having the NiS6 donor set in the
Cambridge Structural Database (CSD ver. 5.32) [24] shows that the
average value of the Ni–S bond lengths [2.262(3) Å] is in good agree-
ment with that of [Ni(but2dtc)3]Br [2.2608(4) Å], however, they are a
bit longer as compared with [Ni(et2dtc)3]C3(CN)5, whose average va-
lue equals 2.252(4) Å. The octahedral distortion can be outlined by
the values of the three axial S–Ni–S angles, whose values signifi-
cantly differ from 180° (see Table 4). For comparison, the corre-
sponding angles equal 167.472(6) in Ni(but2dtc)3]Br and
167.14(8), 164.87(8) and 164.20(7)° in [Ni(et2dtc)3]C3(CN)5. The
dihedral angles formed by the least-square planes fitted through
the NiS2C atoms of a particular hmidtc ligand are 84.74(2)° for NiS1-
S2iC1 and NiS1iS2iiC1i, and 84.75(2)° for NiS1S2iC1 and NiS1iiS2C1ii
(symmetry codes: (i) x ꢁ y ꢁ 1, 1 ꢁ y, z; (ii) 1 ꢁ x, 2 ꢁ x + y, z).
The Fe–Cl bond lengths found within [FeCl4]ꢁ of 9 range from
2.1818(2) to 2.1881(6) Å, while the shortest Niꢀ ꢀ ꢀCl and Niꢀ ꢀ ꢀFe dis-
tances are equal to 4.1043(12) and 6.2862(6) Å, respectively. Its tet-
rahedral geometry is slightly distorted, as can be seen from the bond
angle values (Table 4). Moreover, the distortion can be quantified
Scheme 1. The schematic representation of the [Ni(ndtc)3]+ complex cation of the
nickel(IV) complexes 1–14 given with the list of substituents of the appropriate
dithiocarbamate.
model with CꢁH = 0.99 Å, and Uiso(H) = 1.2Ueq(CH2). The crystal
data and structure refinements are given in Table 1. Molecular
graphics as well as additional structural calculations were drawn
and interpreted using DIAMOND [21] and Mercury [22].
3. Results and discussion
3.1. General properties
Nickel(IV) complexes of the general formulas [Ni(ndtc)3]ClO4 (1–
8) and [Ni(ndtc)3][FeCl4]ꢀyH2O (9–14) were prepared (see Scheme 1)
by oxidation of the starting nickel(II) complexes [Ni(ndtc)2] (a–h;
see Section 2.1) by NOClO4 (1–8) or FeCl3 (9–14). All the reactions
were performed in chloroform and the molar ratios of the starting
complexes and oxidants equaled 1:1.3 (1–8) or 1:2 (9–14). The ob-
tained results of the elemental analysis (C, H, N) and determinations
of chlorine (only for 9–14) and nickel contents correlated well with
the calculated ones (Table 2). The molar conductivity values of 1–14
(see Table 3) are typical for 1:1 electrolytes in acetone [23], which
was used for dissolving the prepared complexes. The complexes
1–8 are diamagnetic, while paramagnetic behavior, specifically
using a four-coordinated geometry index
s
4 = [360° ꢁ (
a + b)]/141°
(a
and b being the largest angles in the four-coordinate species),
which equals 0.991 (the value of 1.000 represents an ideal tetrahe-
dral geometry) [25].
The crystal structure (Fig. 2) of complex 9 contains several types
of van der Waals non-covalent contacts, namely intramolecular
Sꢀ ꢀ ꢀCl and intermolecular C–Hꢀ ꢀ ꢀC, C–Hꢀ ꢀ ꢀCl and Sꢀ ꢀ ꢀS types of con-
tacts, with the shortest donorꢀ ꢀ ꢀacceptor distances of 3.4907(10),
3.493(5), 3.716(3), and 3.4867(7) Å, respectively.
6.01, 6.03, 6.00, 6.15, 6.14 and 6.14 leff/lB, was detected in the case
of 9–14, respectively, due to the presence of the [FeCl4]ꢁ anion in the
Table 2
Results of elemental analysis performed for complexes 1–14.
Complex
Empirical formula
Molecular weight
Yield (%)
Elemental analysis (calc./found, %)
C
H
N
Cl
Ni
[Ni(hmidtc)3]ClO4 (1)
[Ni(indtc)3]ClO4 (2)
[Ni(bzppzdtc)3]ClO4 (3)
[Ni(bz2dtc)3]ClO4 (4)
[Ni(pe2dtc)3]ClO4 (5)
[Ni(bzipdtc)3]ClO4 (6)
[Ni(bzmedtc)3]ClO4 (7)
[Ni(chetdtc)3]ClO4 (8)
[Ni(hmidtc)3][FeCl4] (9)
[Ni(indtc)3][FeCl4] (10)
[Ni(bz2dtc)3][FeCl4] (11)
[Ni(bzmedtc)3][FeCl4] (12)
[Ni(bzipdtc)3][FeCl4]ꢀH2O (13)
[Ni(chetdtc)3][FeCl4]ꢀ0.5H2O (14)
C21H36N3ClNiO4S6
C27H24N3ClNiO4S6
C36H45N6ClNiO4S6
C45H42N3ClNiO4S6
C33H66N3ClNiO4S6
C33H42N3ClNiO4S6
C27H30N3ClNiO4S6
C27H48N3ClNiO4S6
C21H36N3Cl4FeNiS6
C27H24N3Cl4FeNiS6
C45H42N3Cl4FeNiS6
C27H30N3Cl4FeNiS6
C33H44N3Cl4FeNiOS6
C27H49N3Cl4FeNiO0.5S6
681.07
741.04
912.32
975.37
855.44
831.25
747.09
765.23
779.28
839.24
1073.58
845.29
947.47
872.44
44
43
69
47
39
50
45
56
51
66
53
58
45
47
37.03/37.32
43.86/43.87
47.39/46.95
55.41/54.96
46.33/46.36
47.68/47.35
43.41/43.78
42.38/42.65
32.37/32.11
38.64/39.08
50.34/49.87
38.36/38.86
41.83/42.19
37.17/37.87
5.33/5.29
3.26/3.02
4.97/4.32
4.34/4.30
7.78/7.97
5.09/4.91
4.05/4.07
6.32/6.64
4.66/4.24
2.88/2.74
3.94/3.71
3.58/3.71
4.68/4.29
5.66/5.81
6.17/6.09
5.67/5.54
9.21/8.74
4.30/4.07
4.91/4.87
5.06/4.64
5.62/5.17
5.49/5.86
5.39/4.86
5.01/4.74
3.91/3.82
4.97/4.84
4.44/4.32
4.82/4.73
nd
nd
nd
nd
nd
nd
nd
nd
8.62/8.57
7.92/7.86
6.43/6.47
6.02/6.05
6.86/6.81
7.06/7.18
7.86/7.78
7.67/7.55
7.53/7.28
6.99/6.98
5.47/5.48
6.94/6.88
6.19/6.23
6.73/6.67
18.20/17.85
16.90/17.20
13.21/12.78
16.78/16.95
14.97/14.87
16.25/16.41
nd, not determined for safety reasons.

2798
R. Pastorek et al. / Polyhedron 30 (2011) 2795–2800
Table 3
The results of molar conductivity measurements (S cm2 molꢁ1), UV–Vis (ꢂ 103 cmꢁ1) and FTIR (cmꢁ1) spectroscopy, and thermal analysis (TG/DTA) obtained for the nickel(IV)
complexes 1–14.
kM
FTIR
UV–Visa
Thermal analysis
TGb
DTAc
1
2
3
4
5
6
7
8
144.0
136.9
125.6
137.5
141.0
136.8
129.1
126.0
142.4
145.6
127.2
139.5
134.2
144.5
623vs, 1008w, 1086vs, 1519vs
622m, 1008w, 1087vs, 1497vs
623m, 1010m, 1091vs, 1529vs
623m, 1001w, 1091vs, 1522vs
624m, 1005w, 1088vs, 1536vs
622m, 1005m, 1089m, 1501vs
623m, 1002w, 1094vs, 1540vs
623m, 1009m, 1099vs, 1508vs
1006w, 1521vs
1009w, 1496vs
1001w, 1513vs
1002w, 1536vs
1009w, 1499vs
22.0, 29.9
21.0, 27.6
23.0, 26.0
17.8, 20.7
19.4, 23.5
20.7, 26.5
22.1, 27.2
22.4, 27.3
23.0
16.0, 26.9
17.9, 24.6
16.8, 25.9
19.5, 24.0
20.4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
9
115–728
69–477
131–774
58–770
29–796
64–733
231, 243, 285, 363, 423, 528
175, 193, 223, 244, 365, 464
166en, 194, 354
136, 207, 253, 374, 449
40en, 146en, 204, 356, 434, 454
86en, 170, 220, 231, 359, 492
10
11
12
13
14
1007w, 1502vs
a
b
c
Solid state (diffuse–reflectance) spectra.
The temperature range of thermal decomposition (°C).
The position of maxima of exothermic effects (°C) and minima of endothermic effects (°C; symbolized en).
Table 4
Selected bond lengths (Å) and angles (°) of Ni(hmidtc)3][FeCl4] (9).
Bond lengths
Bond angles
Ni1ꢁS1
Ni1ꢁS2
S1–C1
2.2652(5)
2.2597(5)
1.719(2)
1.715(2)
1.308(3)
S1ꢁNi1ꢁS2i
S1ꢁNi1ꢁS1i
S1ꢁNi1ꢁS2ii
S1ꢁNi1ꢁS2
S2ꢁNi1ꢁS2i
Ni1ꢁS1ꢁC1
Ni1ꢁS2iꢁC1
Cl1–Fe1–Cl2
Cl1–Fe1–C11i
76.46(2)
94.57(2)
95.51(2)
167.00(2)
94.82(2)
86.96(7)
87.24(8)
108.79(2)
110.14(2)
S2i–C1
C1–N1
Fe1–Cl1
Fe1–Cl2
2.1881(6)
2.1818(12)
Symmetry codes: (i) x ꢁ y ꢁ 1, 1 ꢁ y, z; (ii) 1 ꢁ x, 2 ꢁ x + y, z
tional experiments have been performed. We measured DMF solu-
tion UV–Vis spectra of the representative complexes involving the
[FeCl4]ꢁ anion (9–14) as well as the CHCl3 spectrum of complex 8
in an effort to find whether the stereochemistry (i.e., coordination
geometry) of the complexes is changed in a solution as compared
to the solid state. As for the representative complex 8 (see Fig. 3),
it may be concluded that the DMF and CHCl3 spectra are nearly iden-
tical and quite comparable with the solid state spectrum with main
maxima at about 27500 and 22500 cmꢁ1, thus showing that no sig-
nificant geometric changes proceed in the vicinity of the central
atoms among the mentioned phases. We also strived to interpret
the spectra of complexes 9–14, involving Ni(IV) and Fe(III) species,
which are influenced by a superposition of both components. For
that reason, we prepared (PhMe3N)[FeCl4] [26], a simple compound
involving the [FeCl4]ꢁ anion, and measured its DMF and solid state
(diffuse-reflectance) UV–Vis spectra. The solid state spectrum of
the compound showed a weak shoulder at 22300 cmꢁ1 and a weak
maximum at 18750 cmꢁ1, while no typical maximum (shoulder)
was observed in the DMF solution spectrum. A comparison of the
DMF spectra of [Ni(bzipdtc)3](ClO4) (6), [Ni(bzipdtc)3][FeCl4]ꢀH2O
(13), and DMF and solid state spectra of (PhMe3N)[FeCl4] is shown
in Fig. 3. Based on the obtained results, we are not able to make an
univocal conclusion explaining how the simultaneous presence of
nickel(IV) and iron(III) species may affect the electronic spectra of
compounds 9–14. Nevertheless, we may draw the conclusion that
the maxima (shoulders) observed at about 22300 and 18700 cmꢁ1
may be ascribed to both the [Ni(ndtc)3]+ complex cations and the
[FeCl4]ꢁ anions, while the maxima (shoulders) at about
20500 cmꢁ1 may be associated with the d–d transitions of the
[Ni(ndtc)3]+ complex cations.
Fig. 1. The molecular structure of [Ni(hmidtc)3][FeCl4] (9) with non-hydrogen
atoms drawn as thermal ellipsoids at the 50% probability level; the hydrogen atoms
are omitted for clarity. Symmetry codes: (i) x ꢁ y ꢁ 1, 1 ꢁ y, z; (ii) 1 ꢁ x, 2 ꢁ x + y, z.
3.3. FTIR, UV–Vis and Mössbauer spectroscopy
The
tic for dithiocarbamate-based organic ligands, showed their max-
ima at 1001–1010 cmꢁ1 of weak to middle intensity [for
(C'S)]
and 1496–1540 cmꢁ1 of very strong intensity [for
(C'N)] (Table
3). The vibrations detected at 622–624 and 1086–1099 cmꢁ1 dem-
onstrated the presence of the perchlorate anion [
4(ClO4ꢁ) and
3(ClO4ꢁ), respectively] in the structure of the [Ni(ndtc)3]ClO4 com-
plexes (1–8).
m(C'S) and m(C'N) vibrations, known as very characteris-
m
m
m
m
The diffuse-reflectance UV–Vis spectra showed two maxima
(only one maximum in the case of 9 and 14) assignable to the d–d
transitions of the prepared octahedral nickel(IV) dithiocarbamato
complexes between 16000 and 30000 cmꢁ1 (Table 3). With the
aim to better understand spectral properties of the studied
complexes, mainly complexes 9–14 which are influenced by the
simultaneous presence of nickel(IV) and iron(III) species, some addi-

R. Pastorek et al. / Polyhedron 30 (2011) 2795–2800
2799
Fig. 2. A part of the crystal structure of [Ni(hmidtc)3][FeCl4] (9), as viewed along the c axis, showing the packing of the molecules within the unit cell and selected non-
covalent contacts (dashed lines) of the C–Hꢀ ꢀ ꢀCl, C–Hꢀ ꢀ ꢀC, Sꢀ ꢀ ꢀCl and Sꢀ ꢀ ꢀS type; the hydrogen atoms not involved in the depicted contacts are omitted for clarity.
Fig. 4. The results of simultaneous TG/DTA analyses of complex 13 performed in a
dynamic air atmosphere (up), simultaneous TG/DSC curves of 13 performed in a
Fig. 3. A comparison of solution and solid state UV–Vis spectra of [Ni(chetdtc)3]ClO4
(6) (on top), and spectra of [Ni(bzipdtc)3](ClO4) (6), [Ni(bzipdtc)3][FeCl4]ꢀH2O (13)
and (PhMe3N)[FeCl4] (down).
dynamic argon atmosphere (middle), and TG curve together with the in situ mass
spectrometry with H2O (m/z = 18) elimination (down). Insets show XRD patterns of
the thermal degradation products.

2800
R. Pastorek et al. / Polyhedron 30 (2011) 2795–2800
The room temperature Mössbauer spectrum of 9 consists of one
Regional Development Fund (CZ.1.05/2.1.00/03.0058), the Opera-
tional Program Education for Competitiveness – European Social
Fund (CZ.1.07/2.3.00/20.0017) of the Ministry of Education, Youth
and Sports of the CzechRepublic. The authors also thank Assoc. Prof.
singlet with an isomer shift of 0.24 mm sꢁ1, which is consistent
with the results of the crystallographic study and it proves the
presence of the tetrahedral [FeCl4]ꢁ anion involving the Fe(III)
ion in the high-spin state.
ˇ
ˇ
Zdenek Šindelár for magnetic susceptibility measurements,
ˇ
Mr. Zdenek Marušák for STA/QMS measurements, and Dr. Jan Filip
3.4. Thermal analysis (TG/DTA)
for XRD measurements.
The thermal properties of the complexes 9–14 were studied by
means of simultaneous TG/DTA analyses (the thermal properties
of 1–8 were not studied because of the presence of the explosive per-
chlorate anion in their structure). All the complexes 9–14 decom-
posed in one step without the formation of thermally stably
intermediates and the process of thermal decomposition is con-
nected withseveral endo- and exo-effects (see Table 3). Interestingly,
the decay of 10 finished at 477 °C, which differs significantly from
other complexes, whose degradation proceeded to 728–796 °C.
Thermal studies also showed that complexes 9–12 are non-solvated,
while 13 and 14 were found to be hydrated. The weight losses de-
tected at the beginning of the TG curves of [Ni(bzipdtc)3][FeCl4]ꢀH2O
(13) and [Ni(chetdtc)3][FeCl4]ꢀ0.5H2O (14) equal 1.7% (1.9% calc. for
H2O), and 1.1% (1.0% calc. for 0.5H2O), respectively, and they were
caused by the water molecules elimination, as proved by the mass
spectrometry of the thermal degradation products, where the frag-
ment corresponding to water molecule was unambiguously identi-
fied in the case of 13 (see Fig. 4). The final product of the thermal
decay of 13 performed in air was identified by XRD as a mixture of
NiFe2O4 (PDF-4 No. 01-074-2081; ca 63%) and Fe2O3 (PDF-4 No.
01-086-2368; ca 37%), while the residue of the analysis carried out
in a dynamic argon atmosphere consists of Fe5Ni4S8 (PDF-4 No.
01-086-2470; ca 86%) and FeS (PDF-4 No. 03-065-6841; ca 14%).
Appendix A. Supplementary data
CCDC 827947 contains the supplementary crystallographic data
for [Ni(hmidtc)3][FeCl4]. 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.
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TheauthorsgratefullythanktheMinistryofEducation,Youthand
Sports of the Czech Republic (MSM6198959218), the Operational
Program Research and Development for Innovations – European