Syntheses, crystal structure and theoretical investigation of novel heteroleptic complexes of nickel(II) with N-R-sulfonyldithiocarbimate and phosphine ligands

Article abstract of DOI:10.1016/j.ica.2011.06.025

Five new complexes of general formula: [Ni(RSO₂NCS ₂)(dppe)], where R = C₆H₅ (1), 4-ClC ₆H₄ (2), 4-BrC₆H₄ (3), 4-IC ₆H₄ (4) and dppe = 1,2-bis(diphenylphosphino)ethane and [Ni(4-IC₆H₄SO₂NCS₂)(PPh ₃)₂] (5), where PPh₃ = triphenylphosphine, were obtained in crystalline form by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate K₂(RSO₂NCS₂) and dppe or PPh₃ with nickel(II) chloride in ethanol/water. The elemental analyses and the IR, ¹H NMR, ¹³C NMR and ³¹P NMR spectra are consistent with the formation of the square planar nickel(II) complexes with mixed ligands. All complexes were also characterized by X-ray diffraction techniques and present a distorted cis-NiS₂P₂ square-planar configuration around the Ni atom. Quantum chemical calculations reproduced the crystallographic structures and are in accord with the spectroscopic data. Rare C-H...Ni intramolecular short contact interactions were observed in the complexes 1-5.

Full text of DOI:10.1016/j.ica.2011.06.025

Inorganica Chimica Acta 376 (2011) 238–244
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Syntheses, crystal structure and theoretical investigation of novel heteroleptic
complexes of nickel(II) with N-R-sulfonyldithiocarbimate and phosphine ligands
b
b
b
Marcelo Ribeiro Leite Oliveira a, , Eduardo de Faria Franca , Celice Novais , Silvana Guilardi ,
Iterlandes Machado Jr. a, Javier Ellena c, Jorge Amim Jr. a, Vito Modesto De Bellis d,
Mayura Marques Magalhães Rubinger a
⇑
a Departamento de Química, Universidade Federal de Viçosa, Viçosa MG, CEP 36571-000, Brazil
b Instituto de Química, Universidade Federal de Uberlândia, Uberlândia MG, CEP 38408-100, Brazil
c Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos SP, CEP 13500-970, Brazil
d Departamento de Química, Universidade Federal de Minas Gerais, Belo Horizonte MG, CEP 31270-901, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Five new complexes of general formula: [Ni(RSO2N@CS2)(dppe)], where R = C6H5 (1), 4-ClC6H4 (2), 4-
BrC6H4 (3), 4-IC6H4 (4) and dppe = 1,2-bis(diphenylphosphino)ethane and [Ni(4-IC6H4SO2N@CS2)(PPh3)2]
(5), where PPh3 = triphenylphosphine, were obtained in crystalline form by the reaction of the appropri-
ate potassium N-R-sulfonyldithiocarbimate K2(RSO2N@CS2) and dppe or PPh3 with nickel(II) chloride in
ethanol/water. The elemental analyses and the IR, 1H NMR, 13C NMR and 31P NMR spectra are consistent
with the formation of the square planar nickel(II) complexes with mixed ligands. All complexes were also
characterized by X-ray diffraction techniques and present a distorted cis-NiS2P2 square-planar configura-
tion around the Ni atom. Quantum chemical calculations reproduced the crystallographic structures and
are in accord with the spectroscopic data. Rare C–HꢀꢀꢀNi intramolecular short contact interactions were
observed in the complexes 1–5.
Received 4 March 2011
Received in revised form 6 June 2011
Accepted 10 June 2011
Available online 16 June 2011
Keywords:
Dithiocarbimates
Phosphines
Nickel complexes
Crystal structures
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
4-BrC6H4 (3), 4-IC6H4 (4), and [Ni(4-IC6H4SO2N@CS2)(PPh3)2] (5).
The complexes were obtained in the crystalline form by the
The interest in the syntheses and characterization of dithiocarb-
imate metal complexes is related to their similarities with the
dithiocarbamate compounds, which have a wide range of applica-
tions. For example, dithiocarbamates are used in the rubber vulca-
nization process [1,2] as well as several dithiocarbamates salts and
complexes have been used as fungicides [2,3]. In fact, recently it
was demonstrated that dithiocarbimates are also fungicides and
vulcanization accelerators [4,5]. Additionally, heteroleptic group
10 metal complexes with sulfonyldithiocarbimate and phosphines
have shown interesting molecular electrical conducting and photo-
luminescent properties. Besides, their structures present rare
C–HꢀꢀꢀM intramolecular short contact interactions [6,7].
reaction of NiCl2ꢀ6H2O with PPh3 or dppe and the dithiocarbimate
anions derived from sulfonamides. These complexes were charac-
terized by IR, 1H, 13C and 31P NMR, elemental analyses, single
crystal X-ray diffraction techniques, and semiempirical quantum
chemical calculations.
2. Experimental
2.1. Material and reagents
The solvents, carbon disulfide and potassium hydroxide were
purchased from Vetec and used without further purification. The
benzenesulfonamide, 4-chlorobenzenesulfonamide, 4-bromophe
nylsulfonyl chloride, 4-iodophenylsulfonyl chloride, nickel(II) chlo-
ride hexahydrate, triphenylphosphine and 1,2-bis(diphenylphos-
phino)ethane were purchased from Aldrich. The 4-iodobenzenesu
lphonamide and the 4-bromobenzenesulphonamide were pre-
pared from the appropriate sulfonyl chloride as described else-
where [11]. The N-R-sulfonyldithiocarbimate potassium salts dih
ydrate were prepared in dimethylformamide from the sulfonamid
es analogously as described in the literature [12,13]. Melting points
were determined with a Mettler FP5 equipment. Microanalyses for
Less than ten nickel(II) complexes of this class are structurally
characterized: [Ni(RSO2N@CS2)(PPh3)2] (R = 2-CH3C6H4, 4-CH3C6
H4, 4-BrC6H4, and 2,5-Cl2C6H3) [8,9], [Ni(RSO2N@CS2)dppe] (R =
CH3, CH3CH2, 2-CH3C6H4 and 4-CH3C6H4) [6,10]. Considering the
need to increase the knowledge on the physical and chemical prop-
erties of this group of complexes, we have prepared five new
compounds: [Ni(RSO2N@CS2)(dppe)] R = C6H5 (1), 4-ClC6H4 (2),
⇑
Corresponding author.
E-mail address: marcelor@ufv.br (M.R.L. Oliveira).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.06.025

M.R.L. Oliveira et al. / Inorganica Chimica Acta 376 (2011) 238–244
239
C, H and N were obtained from a Perkin–Elmer 2400 CHN. Nickel
was analyzed by atomic absorption with a Hitachi Z-8200 Atomic
Absorption Spectrophotometer. The IR spectra were recorded with
a Perkin–Elmer 283 B infrared spectrophotometer using CsI pellets.
The 1H (400 MHz), 13C (100 MHz) and 31P (162 MHz) NMR spectra
of the complexes were recorded at 300 K on a Bruker Advance RX-
400 spectrophotometer in CDCl3 with TMS (H3PO4 for 31P NMR
spectra) as internal standard.
2.2.3. [Ni(4-BrC6H4SO2N@CS2)dppe] (3)
Anal. Calc. C, 51.65; H, 3.68; N, 1.83; Ni, 7.65. Found: C, 51.40; H,
3.55; N, 1.80; Ni, 7.90%. Mp with decomposition (°C): 206.5–208.5.
IR (most important bands) (cmꢁ1): 1443
m
(C@N); 1308
mass(SO2);
1150 msym(SO2); 922 mass(CS2) and 358 m
(NiS). 1H NMR (d), J(Hz):
7.85–7.81 (m, 2H, H2 and H6 of the aromatic ring of the dithiocar-
bimato); 7.71–7.67 (m, 8H, H2 and H6 of the aromatic rings of
dppe); 7.51–7.45 (m, 14H, H3, H4 and H5 of the aromatic rings
of the dppe and H3 and H5 of the aromatic ring of the dithiocarbi-
mato); 2.35 (d, 4H JHP = 17, CH2CH2). 13C{1H} NMR (d): 200.92
(N@CS2); 141.58 (C1); 133.04 (C4); 131.45 (C3 and C5); 126.51
(C2 and C6). dppe signals: 132.88 (t, JCP = 5.3, C2 and C6); 132.00
(s, C4); 128.52 (t, JCP = 5.2, C3 and C5); 128.30 (t, JCP = 22, C1);
26.57 (t, JCP = 23, CH2CH2). 31P NMR (d): 57.19 (s).
2.2. Syntheses
The syntheses were performed according to the Scheme 1. A
solution of N-R-sulfonyldithiocarbimate dihydrate (1.0 mmol) in
water (10 mL) was added to a suspension of the appropriate phos-
phine (2.0 mmol for PPh3 and 1.0 mmol for dppe) in ethanol
(40 mL). Nickel(II) chloride hexahydrate (1.0 mmol) was added to
the suspension and the reaction mixture was stirred for six hours
at room temperature. The color of the suspension changed from
green to pink/red. The solid product was filtered, washed with dis-
tilled water and ethanol, and dried under reduced pressure for one
day. The yield was ca. 80%. Suitable crystals for X-ray structure
analysis were obtained after slow evaporation of solutions of the
compounds in dichloromethane/methanol and few drops of water.
2.2.4. [Ni(4-IC6H4SO2N@CS2)dppe] (4)
Anal. Calc. C, 48.67; H, 3.47; N, 1.72; Ni, 7.21. Found: C, 48.40; H,
3.32; N, 1.92; Ni, 6.89%. Mp with decomposition (°C): 203.5–207.3.
IR (most important bands) (cmꢁ1): 1463
m(C@N); 1301
mass(SO2);
1120 msym(SO2); 920 mass(CS2) and 335 m
(NiS). 1H NMR (d), J(Hz):
7,72–7,65 (m, 10H, H2 and H6 of the aromatic ring of the dithioc-
arbimato and dppe); 7.52–7.41 (m, 14H, H3, H4 and H5 of the aro-
matic rings of the dppe and H3 and H5 of the aromatic ring of the
dithiocarbimato); 2.35 (d, 4H JHP = 17, CH2CH2). 13C{1H} NMR (d):
200.58 (N@CS2); 142.30 (C1); 137.31 (C3 and C5); 129.18 (C2
and C6); 98.79 (C4). dppe signals: 132.87 (t, JCP = 5.3, C2 and C6);
131.87 (s, C4); 129.40 (t, JCP = 5.2, C3 and C5); 128.25 (t, JCP = 22
C1); 26.13 (t, JCP = 23, CH2CH2). 31P NMR (d): 58.46 (s).
2.2.1. [Ni(C6H5SO2N@CS2)dppe] (1)
Anal. Calc. C, 57.57; H, 4.25; N, 2.05; Ni, 8.53. Found: C, 57.19; H,
4.38; N, 2.04; Ni, 8.16%. Mp with decomposition (°C): 201.5–202.5.
IR (most important bands) (cmꢁ1): 1436
1151 msym(SO2); 917 mass(CS2) and 360 m
m
(C@N); 1310
mass(SO2);
(NiS). 1H NMR (d), J(Hz):
7.98–7.95 (m, 2H, H2 and H6 of the aromatic ring of the dithiocar-
bimato); 7.76–7.65 (m, 8H, H2 and H6 of the aromatic rings of
dppe); 7.66–7.33 (m, 15H, H3, H4 and H5 of the aromatic rings
of the dithiocarbimato and dppe); 2.34 (d, 4H JHP = 17, CH2CH2).
13C{1H} NMR (d): 199.32 (N@CS2); 142.46 (C1); 131.62 (C4);
128.16 (C3 and C5); 127.44 (C2 and C6). dppe signals: 132.88 (t,
JCP = 5.3, C2 and C6); 131.79 (s, C4); 129.35 (t, JCP = 5.2, C3 and
C5); 128.23 (t, JCP = 22, C1); 26.01 (t, JCP = 23, CH2CH2). 31P NMR
(d): 56.92 (s).
2.2.5. [Ni(4-IC6H4SO2N@CS2)(PPh3)2] (5)
Anal. Calc. C, 54.91; H, 3.64; N, 1.49; Ni, 6.24. Found: C, 54.85; H,
3.58; N, 1.43; Ni, 6.10%. Mp with decomposition (°C): 192.9–194.3.
IR (most important bands) (cmꢁ1): 1451
m
(C@N); 1315
mass(SO2);
1151 msym(SO2); 933 mass(CS2) and 341 m
(NiS). 1H NMR (d): 7,75–
7,26 (m, 34H, aromatic rings). 13C{1H} NMR (d): 141.99 (C1);
137.16 (C3 and C5); 128.57 (C2 and C6); 98.75 (C4) triphenylphos-
phine signals: 134.30 (C2 and C6); 130.75 (C4); 129.57 (C1);
128.37 (C3 and C5). 31P NMR (d): 33.68 (s).
2.2.2. [Ni(4-ClC6H4SO2N@CS2)dppe] (2)
2.3. X-ray diffraction studies
Anal. Calc. C, 54.83; H, 3.90; N, 1.94; Ni, 8.12. Found: C, 54.69; H,
3.74; N, 1.83; Ni, 8.00%. Mp with decomposition (°C): 220.0–221.1.
Diffraction data for all crystals were collected on an Enraf–Non-
ius Kappa-CCD diffractometer using a graphite monochromator
with Mo Ka radiation (0.71073 Å), at room temperature for the
IR (most important bands) (cmꢁ1): 1443
m
(C@N); 1308
mass(SO2);
1147
msym(SO2); 922
mass(CS2) and 355
m
(NiS). 1H NMR (d), J(Hz):
7,92–7,88 (m, 2H, H2 and H6 of the aromatic ring of the dithiocar-
bimato); 7.75–7.67 (m, 8H, H2 and H6 of the aromatic rings of
dppe); 7.53–7.30 (m, 14H, H3, H4 and H5 of the aromatic rings
of the dppe and H3 and H5 of the aromatic ring of the dithiocarbi-
mato); 2.35 (d, 4H JHP = 17, CH2CH2). 13C{1H} NMR (d): 200.25
(N@CS2); 141.04 (C1); 137.84 (C4); 128.36 (C3 and C5); 129.08
(C2 and C6). dppe signals: 132.88 (t, JCP = 5.3, C2 and C6); 131.88
(s, C4); 129.39 (t, JCP = 5.2, C3 and C5); 128.20 (t, JCP = 22, C1);
26.06 (t, JCP = 23, CH2CH2). 31P NMR (d): 57.23 (s).
complexes 1, 4 and 5 and at lower temperature for the complexes
2 and 3. Data collections were made using the COLLECT program [14]
up to 50° in 2h with redundancy of four. Final unit cell parameters
were based on all reflections. Integration and scaling of the reflec-
tions, correction for Lorentz and polarization effects were per-
formed with the HKL DENZO-SCALEPACK system of programs [15].
Multi-scan absorption corrections were applied for the complexes
1, 2 and 4 and numerical absorption corrections (GAUSSIAN) were
applied for the complexes 3 and 2 using the program SORTAV [16].
dppe
[Ni(RSO2N=CS2)dppe]
NiCl2.6H2O, EtOH/H2O
1, 2, 3, 4
RSO2N=CS2K2.2H2O
8H O, 2KCl
-
-
2 PPh3
2
[Ni(RSO2N=CS2)(PPh3)2]
5
1 (R = C6H5), 2 (R = 4-ClC6H4), 3 (R = 4-BrC6H4), 4 and 5 (R = 4-IC6H4)
Scheme 1. Syntheses of 1–5.

240
M.R.L. Oliveira et al. / Inorganica Chimica Acta 376 (2011) 238–244
Table 2
Structures were solved by direct methods (SHELXS-97) and re-
fined (SHELXL-97) by full-matrix least-squares on all F2 data [17].
All the hydrogen atoms were placed in geometrically idealized
positions [17]. Anisotropic thermal parameters were assigned to
all non-hydrogen atoms. For 2, the phenyl rings C14–C19 and
C20–C25 of the dppe ligand were disordered over two different ori-
entations with occupancy of 50%. In complex 3, the phenyl ring C8–
C13 of the dppe ligand was disordered over two sites with occu-
pancy factors of 60% and 40%. In complex 5, the phenyl ring C2–
C7 and iodine atom of the dithiocarbimato ligand were disordered
over two sites with occupancies 70% and 30%. For all disordered
rings the bond lengths Car–Car and angles Car–Car–Car were fixed
in 1.39 Å and 120.0°, respectively.
Selected geometrical parameters (,).
1
2
3
4
5
Bond length(Å)
Ni–S1
Ni–S2
Ni–P1
Ni–P2
C1–S1
C1–S2
C1–N
2.1870(6)
2.2083(7)
2.1659(7)
2.1650(7)
1.744(2)
1.746(3)
1.290(3)
2.1884(5)
2.2078(5)
2.1754(4)
2.1728(4)
1.739(2)
1.740(2)
1.299(2)
2.1889(8)
2.2035(8)
2.1681(7)
2.1703(8)
1.7373(3)
1.735(3)
2.191(1)
2.1969(1)
2.153(1)
2.163(1)
1.724(4)
1.739(4)
1.317(5)
2.184(1)
2.2203(9)
2.2203(9)
2.2269(9)
1.738(3)
1.735(3)
1.295(4)
1.303(3)
Bond angle(o)
S1–Ni–S2
P1–Ni–P2
P1–Ni–S1
P2–Ni–S2
S1–C1–S2
S1–C1–N
S2–C1–N
C1–N–S3
79.24(3)
86.57(3)
97.67(3)
96.53(3)
106.7(1)
132.3(2)
120.8(2)
125.3(2)
79.02(2)
87.93(2)
94.693(7)
98.66(2)
107.02(9)
131.1(1)
121.7(1)
120.6(1)
79.17(3)
88.00(3)
95.68(3)
97.52(3)
107.5(1)
130.6(2)
121.9(2)
120.6(2)
79.79(4)
87.90(4)
94.64(4)
97.69(4)
108.7(2)
131.6(3)
119.7(3)
122.4(3)
78.16(3)
98.87(3)
91.21(4)
92.53(4)
106.2(2)
131.4(3)
122.4(3)
121.6(2)
The absolute configuration of the compounds 1 and 4 were estab-
lished by evaluation of the anomalous dispersion effects [18]. Struc-
tural diagrams were drawn using ORTEP3 [19] and the program WINGX
1.70.01 [20] was used to prepare materials for publication. Crystal
data and details on data collection and refinement are summarized
in Table 1. Selected bond and angles are given in Table 2.
2.4. Theoretical calculations
1–4 are soluble in acetonitrile, dimethylformamide, dimethylsulf-
oxide, chloroform and dichloromethane, and insoluble in water,
methanol and ethanol. The complex 5 showed very little solubility
in chloroform and dichloromethane and is insoluble in the other
above mentioned solvents.
The structures of the metal complexes 1–5 as determined by X-
ray crystallography analysis were fully optimized with the PM6
semiempirical Hamiltonian [21] implemented in the MOPAC2009
software package [22]. The calculations were performed for the
isolated complexes and their ligands using a SCF criterion of
0.0001 kcal/mol. For all complexes, the geometry and charge drifts
were evaluated before and after the complex formation.
There are no strong or medium bands in the 1400–1600 cmꢁ1
region in the IR spectra of the potassium dithiocarbimates related
to the complexes 1–5, and their mCN band was observed around
1260 cmꢁ1 [23,24]. This low value indicates a great contribution
of the canonical forms (a) and (b) for the resonance hybrid (Scheme
2). A strong band observed around 1455 cmꢁ1 in the spectra of the
3. Results and discussion
complexes 1–5 was assigned to the
mCN. The masymCS2 was ob-
served at higher frequency in the spectra of the potassium salts
The complexes 1–5 were prepared as shown in Scheme 1. They
are quite stable at the ambient conditions. The dppe complexes
of dithiocarbimates (ca. 955 cmꢁ1) [23,24] than in the spectra of
Table 1
Crystallographic data and structure refinement summary for complexes 1–5.
Complex
1
2
3
4
5
Formula
C
33H29NNiO2P2S3
C33H28ClNNiO2P2S3
722.84
monoclinic
P21/c
C33H28BrNNiO2P2S3
767.30
monoclinic
P21/c
C33H28INNiO2P2S3
814.29
orthorhombic
P212121
C43H34INNiO2P2S3
940.44
orthorhombic
Pbca
Formula weight
Crystal system
Space group
688.40
orthorhombic
P212121
T (K)
293(2)
210(2)
210(2)
293(2)
293(2)
Crystal size (mm)
Unit cell dimensions (Å)
0.20 ꢂ 0.20 ꢂ 0.20
a = 12.3795(2)
b = 12.4137(2)
c = 19.7795(4)
0.353 ꢂ 0.328 ꢂ 0.274
a = 10.8105(2)
b = 27.6195(6)
c = 10.9922(2)
95.354(1)°
3267.74(11)
4
0.417 ꢂ 0.132 ꢂ 0.108
a = 10.77 81(2)
b = 27.2057(6)
c = 11.4335(3)
95.389(1)°
3337.78(13)
4
0.40 ꢂ 0.40 ꢂ 0.40
a = 10.1544(2)
b = 15.1327(3)
c = 21.9260(5)
0.244 ꢂ 0.128 ꢂ 0.064
a = 16.5156(2)
b = 18.6092(3)
c = 25.5899(5)
b (°)
V (Å3)
Z
3039.62(9)
4
1.504
3369.23(12)
4
1.605
7864.9(2)
8
1.588
Dcalc (g cmꢁ3
)
1.469
0.997
1.527
2.093
l
(Mo K
a
) (mmꢁ1
)
0.983
1.804
1.558
F(0 0 0)
1424
1488
1560
1632
3792
Transmission factors: minimum, maximum
h Range for data collection (°)
Index range
0.8279, 0.9116
3.11–27.48
ꢁ16 6 h 6 16
ꢁ16 6 k 6 11
ꢁ25 6 l 6 25
20659
0.994, 1.008
1.47–27.48
ꢁ13 6 h 6 14
ꢁ35 6 k 6 33
ꢁ14 6 l 6 14
26826
0.59, 0.856
2.91–26.373
ꢁ11 6 h 6 22
ꢁ32 6 k 6 34
ꢁ13 6 l 6 14
35481
0.982, 1.021
3.05–27.48
ꢁ12 6 h 6 13
ꢁ18 6 k 6 19
ꢁ28 6 l 6 28
21929
0.752, 0.904
2.94–26.03
ꢁ15 6 h 6 20
ꢁ22 6 k 6 14
ꢁ31 6 l 6 31
40896
Reflections collected
Independent reflections (Rint
Reflections I > 2 (I)
Number of parameters refined
Final R for I > 2
(I)a
)
6940 (0.0533)
5913
379
R1 = 0.0336
wR2 = 0.0664
R1 = 0.0477
wR2 = 0.0705
ꢁ0.001(9)
1.030
7372 (0.0450)
6731
376
R1 = 0.0309
wR2 = 0.0726
R1 = 0.0351
wR2 = 0.0750
–
6789 (0.0672)
4837
382
R1 = 0.0380
wR2 = 0.0940
R1 = 0.0662
wR2 = 0.1080
–
7707 (0.0556)
6201
388
R1 = 0.0379
wR2 = 0.0740
R1 = 0.0596
wR2 = 0.0824
ꢁ0.012(13)
1.031
7736 (0.0726)
5208
481
R1 = 0.0402
wR2 = 0.1031
R1 = 0.0757
wR2 = 0.1233
–
r
r
R Indices (all data)a
Absolute structure parameter
Goodness-of-fit (GOF) on F2
Residual electron density (e Åꢁ3
1.070
0.359 and ꢁ0.339
1.049
0.606 and ꢁ0.648
1.068
0.698 and ꢁ0.775
)
0.340 and ꢁ0.411
0.414 and ꢁ0.787
P
P
P
P
(||Fo| ꢁ |Fc||)/ |Fo|; wR2 = [ w(|F2o| ꢁ |Fc2|)2/ w|Fo2|2]1/2
.
a
R1
=

M.R.L. Oliveira et al. / Inorganica Chimica Acta 376 (2011) 238–244
241
_
_
_
S
S
S
_
S
S
RSO2
N
C
RSO2
N
c
C
RSO2
N
C
_
_
S
a
b
Scheme 2. Three canonical forms for N-R-sulfonyldithiocarbimate anion.
Fig. 3. X-ray molecular structure of 3. Displacement ellipsoids are shown at the 50%
probability level.
Fig. 1. X-ray molecular structure of 1. Displacement ellipsoids are shown at the 50%
probability level.
Fig. 4. X-ray molecular structure of 4. Displacement ellipsoids are shown at the 50%
probability level.
the 300–400 cmꢁ1 range assigned to the NiS vibrations [25]. The
m
NiP band was not observed above 200 cmꢁ1
.
The NMR spectra of 1–5 were typical for diamagnetic species.
The 1H NMR spectra of the complexes showed the signals for the
hydrogen atoms of the 1,2-bis(diphenilphosphino)ethane (1–4)
and the triphenylphosphine (5) groups. The aromatic 1H NMR sig-
nals of the dithiocarbimate anions were superimposed by the
phosphine ligands. The integration curves of the PCH2CH2P signals
on the 1H NMR spectra of 1–4, compared to the areas of the aro-
matic rings signals (dppe plus XC6H4) were consistent with a 1:1
proportion between the 1,2-bis(diphenylphosphino)ethane ligand
and the dithiocarbimate anions. The 13C NMR spectra of com-
pounds 1–4 showed all the expected signals. Due the very low sol-
ubility of 5, the N@CS2 (C1) signal was not observed in its 13C NMR
spectrum. Considering that the canonical form (c) (Scheme 2) is
more important for the complexes than for the ligands, then the
C1 carbon atom should be more shielded in the complexes. As ex-
pected, in the 13C NMR spectra of compounds 1–4 the (C1) signal
was shifted to higher field if compared with the spectra of the
ligands.
Fig. 2. X-ray molecular structure of 2. Displacement ellipsoids are shown at the 50%
probability level.
the complexes (ca. 925 cmꢁ1). The shifts observed in the
and CN in the spectra of the complexes when compared with
masymCS2
m
the spectra of the ligands, are consistent with the increased impor-
tance of the canonical form (c) after complexation (Scheme 2). The
spectra of the complexes also show the expected medium band in

242
M.R.L. Oliveira et al. / Inorganica Chimica Acta 376 (2011) 238–244
Table 4
Intra and intermolecular interactions parametersa (Å, °) for 1–5.
Donor-WꢀꢀꢀAcceptor
D–W
WꢀꢀꢀA
DꢀꢀꢀA
DWA
1
C7–H7ꢀꢀꢀO1
C9–H9ꢀꢀꢀS1
C28–H28ꢀꢀꢀO1i
C15–H15ꢀꢀꢀNi
0.93
0.93
0.93
0.93
2.48
2.77
2.59
2.83
2.874(4)
3.301(3)
3.401(4)
3.396(3)
106
117
147
120
2
C9–H9ꢀꢀꢀS1
C32–H32bꢀꢀꢀO2i
C180ꢀꢀꢀClii
0.93
0.97
–
0.93
0.93
2.73
2.40
–
2.71
2.83
3.296(2)
3.350(2)
3.244(1)
3.28(1)
120
168
–
120
118
⁄C15–H15ꢀꢀꢀNi
⁄C150–H150ꢀꢀꢀNi
3.36(1)
3
C3–H3ꢀꢀꢀO1
C9–H9ꢀꢀꢀS1
C12–H12ꢀꢀꢀO2i
C32–H32bꢀꢀꢀO2ii
C5–BrꢀꢀꢀCgiii
C15–H15ꢀꢀꢀNi
0.93
0.93
0.93
0.97
1.895(3)
0.93
2.57
2.65
2.57
2.44
3.4895(17)
2.68
2.937(4)
3.29(2)
3.39(1)
3.397(4)
5.019(4)
3.259(4)
104
126
147
168
135.4(1)
121
4
C3–H3ꢀꢀꢀO1
0.93
0.93
0.93
0.93
0.97
0.97
2.103(4)
0.93
2.56
2.59
2.53
2.55
2.55
2.85
3.070(4)
2.85
2.914(5)
3.475(5)
3.279(6)
3.432(5)
3.269(5)
3.394(5)
5.164(4)
3.405(5)
103
159
138
159
131
116
173.0(2)
120
C4–H4 O1i
C17–H17ꢀꢀꢀO2ii
C31–H31ꢀꢀꢀO2iii
C33–H33aꢀꢀꢀNiii
C33–H33bꢀꢀꢀS2iii
C5–IꢀꢀꢀO1iv
Fig. 5. X-ray molecular structure of 5. Displacement ellipsoids are shown at the 50%
probability level.
C15–H15ꢀꢀꢀNi
The 31P NMR spectra obtained at 300 K exhibited only one sig-
nal at ca. 56 d for the complexes 1–4 and at ca. 33 d for the triphen-
ylphosphine complex 5. These chemical shifts are in accordance to
those observed for analogous complexes: [Ni(RSO2N@CS2)(dppe)]
(R = CH3, CH3CH2 and 2-CH3C6H4) [10] and [Ni(PPh3)2
(RSO2N@CS2)] (R = 2-CH3C6H4, 4-CH3C6H4 and 4-BrC6H4) [8].
Although the phosphorus atoms are not equivalent, no split was
observed at 300 K as observed for analogous complexes at 240 K
[10].
The X-ray molecular structures of the complexes here studied
are illustrated in Figs. 1–5. The complexes crystallize in monoclinic
or orthorhombic system in P21/c (complexes 2 and 3), P212121
(complexes 1 and 4) or Pbca (complex 5) space groups. In all com-
plexes, the nickel atom is coordinated by two sulfur atoms of the
dithiocarbimato ligand and by two phosphorus atoms of the phos-
phines. The cis-NiS2P2 fragment have a distorted square planar
geometry due to the small angle S1–Ni–S2 (ca. 79°) associated with
the bidentate chelation of the dithiocarbimato moiety.
5
C3–H3ꢀꢀꢀO1
C29–H29ꢀꢀꢀO1i
C5–IꢀꢀꢀCgii
C50–I0ꢀꢀꢀCgii
C15–H15ꢀꢀꢀNi
C33–H33ꢀꢀꢀNi
0.93
0.93
2.05(1)
2.15(3)
0.93
2.51
2.46
3.720(3)
3.682(6)
2.73
2.90(1)
3.320(4)
5.58(1)
5.47(3)
3.339(4)
3.384(3)
105
154
148.7(3)
137.4(7)
124
0.93
2.81
121
Cg: centroid generated by the aromatic ring C26–C31; ⁄disordered atom.
a
Symmetry codes for 1: (i) x ꢁ 1/2, 5/2 ꢁ y, 2 ꢁ z; for 2: (i) 1 + x, y, z; (ii) x, 1/
2 ꢁ y, z ꢁ 1/2; for 3: (i) 1 + x, 3/2 ꢁ y, z ꢁ 1/2; (ii) 1 + x, y, z; (iii) x, 1/2 ꢁ y, ꢁ1/2 + z;
for 4: (i) 1/2 + x, 1/2 ꢁ y, 1 ꢁ z; (ii) ꢁ1/2 + x, 1/2 ꢁ y, 1 ꢁ z; (iii) 1 ꢁ x, 1/2 + y, 1/2 ꢁ z;
(iv) ꢁ1 + x, y, z; for 5: (i) ꢁ1/2 + x, y, 1/2 ꢁ z; (ii) 1/2 ꢁ x, ꢁy, 1/2 + z.
Table 5
Root mean square deviation (Å) of crystallographic and theoretical structures after
fitting the second structure on the first one.
Complex All structure fitting Fitting between planar fragment NCS2NiP2
1
2
3
4
5
0.359
0.480
0.770
0.457
0.384
0.053
0.083
0.088
0.068
0.078
The Ni–P distances (Table 2) are symmetric in the complexes 1–
5 (the difference between Ni–P1 and Ni–P2 is less than 0.01 Å), as
reported for similar compounds [10]. The P–Ni–P angles in 1–4 (ca.
87.5o) are shorter than in 5 (98.87o) due to the steric repulsion
Table 3
Comparison between selected crystallographic and spectroscopic data for the CN bond in the complexes 1–5 and related compounds.
Compounds
CN length (Å)
m
CN (cmꢁ1
)
13C NMR (NCS2) (ppm)
Charge on C(1)
K2 (C6H5SO2N@CS2)ꢀ2H2Oa,b
1.342(9)
1.290(3)
1.354(5)
1.299(2)
–
1.303(3)
–
1.317(5)
1.295(4)
1267
1452
1261*
1430
1261*
1443
1280
1463
1451
223.19
199.32
225.72
200.25
225.74
200.92
225.62
200.58
not observed
0.639
0.397
0.654
0.395
0.651
0.394
0.648
0.396
0.392
[Ni(C6H5SO2N@CS2)(dppe)] (1)
K2 (4-ClC6H4SO2N@CS2)ꢀ2H2Oa,b
[Ni(4-ClC6H4SO2N@CS2)(dppe)] (2)
K2 (4-BrC6H4SO2N@CS2)ꢀ2H2Oa
[Ni(4-BrC6H4SO2N@CS2)(dppe)] (3)
K2 [4-IC6H4SO2N@CS2]ꢀ2H2Oc
[Ni(4-IC6H4SO2N@CS2)(dppe)] (4)
[Ni(4-IC6H4SO2N@CS2)(PPh3)2] (5)
*
This work.
a
Ref. [24].
Ref. [13].
b
c
Ref. [23].

M.R.L. Oliveira et al. / Inorganica Chimica Acta 376 (2011) 238–244
243
Table 6
Atomic charges on the atoms of the fragment N@CS2 of the dithiocarbimate moiety.
Complex
Before complexation
After complexation
S1
S1
S2
C1
N
S2
C1
N
1
2
3
4
5
ꢁ0.988
ꢁ0.975
ꢁ0.974
ꢁ0.960
ꢁ0.960
ꢁ0.848
ꢁ0.841
ꢁ0.838
ꢁ0.841
ꢁ0.841
0.639
0.654
0.651
0.648
0.648
ꢁ0.926
ꢁ0.945
ꢁ0.942
ꢁ0.944
ꢁ0.944
ꢁ0.560
ꢁ0.540
ꢁ0.543
ꢁ0.552
ꢁ0.547
ꢁ0.429
ꢁ0.442
ꢁ0.442
ꢁ0.442
ꢁ0.432
0.397
0.395
0.394
0.396
0.392
ꢁ0.819
ꢁ0.825
ꢁ0.824
ꢁ0.824
ꢁ0.818
between the phenyl rings of the PPh3. This effect is also responsible
for the greater Ni–P distances in bis(triphenylphosphine) complex
5 (ca. 2.22 Å) than in the diphosphine complexes 1–4 (ca. 2.17 Å).
The Ni–S bonds in complexes 1–5 are in the same range of analo-
gous compounds [10].
m
C@N band in the IR spectra of the complexes have been explained
in the same terms. The quantum chemical calculations for com-
pounds 1–5 are in accord with these assumptions. Before the com-
plexation there was a negative charge density concentrated around
N, S1 and S2 atoms of the N-R-sulfonyldithiocarbimate ligands,
correlated to the canonical forms (a) and (b) (Scheme 2). After
the complexation, a large drift of electrons from the SO2NCS2 frag-
ment to the Ni atom was observed. The major charge variation oc-
curs on the sulfur atoms bonded to the Ni atom, as shown on Table
6. It is interesting to note that the charge in the carbon atom of the
N@CS2 group change from ca. 0.65–0.39. This fact is in accord with
the 13C NMR data (Table 3) for an increase of the shielding in this
atom leads to a shift in the signal of the dithiocarbimate carbon
from ca. d 225 in the spectra of the ligands to ca. d 200 in the spec-
tra of the complexes.
An electron drift from the halogen atoms is also observed, but
there are no significant charge transfer involving the phenyl rings.
The only significant electron drift on the dppe and PPh3 ligands oc-
curs from the phosphorus atoms to the metal. The calculated
charges on the phosphorus atoms of the dppe and PPh3 are ca.
0.39 and 0.38, respectively. These values raise to ca. 0.84 for dppe
and 0.83 for PPh3 after the complexation.
In all complexes the C–S bond lengths, of the NCS2 fragment, are
nearly equal and are slightly shorter than typical C–S single bonds
(ca. 1.81 Å) due to partial
p-delocalization in the S–C–S group.
The spectroscopic data and X-ray experiments showed that the
C–N bond have a greater double bond character and are shorter
than in the free ligands for 1 and 2 [13] (Table 3). Similar behavior
is observed for others nickel complexes with dithiocarbimato li-
gands [10].
The S1–C1–N angles are significantly greater than S2–C1–N due
to the repulsive interaction between the RSO2 group and S1 atom,
which are in cis position in relation to the C1–N bond. The torsion
angles of C1–N–S3–C2 describing the conformation of the dithioc-
arbimato ligand are almost equal in the compounds 2, 3 and 4
bearing halogen atoms in the RSO2 group [ꢁ70.0(2)°, ꢁ68.4(3)°
and ꢁ70.5(4)°, respectively]. The complex 1 (with no substituent
in the phenyl ring) has similar conformation with a dihedral angle
of ꢁ38.3(3)°. This angle in the complex 5 [64.2(5)° for the most
occupied position] agrees, in modulus, with observed values in
other analogous complexes [8].
4. Conclusion
The intra and intermolecular contacts are shown in Table 4. All
complexes exhibit intramolecular interactions and C–HꢀꢀꢀO inter-
molecular contacts. The complexes which have 4-XC6H4 fragments
show intermolecular interactions involving the halogen atoms in
[0 0 1] (compounds 2, 3 and 5) or [1 0 0] (compound 4) directions.
The monoclinic compounds (2 and 3) present a weak Csp3–HꢀꢀꢀO
intermolecular interaction involving the same atoms (C32–
H32ꢀꢀꢀO2). Only compound 4 have intermolecular interactions C–
HꢀꢀꢀN and C–HꢀꢀꢀS.
The five new complexes obtained in this work showed interest-
ing relation between spectroscopic and crystallographic data. For
all of the complexes it was observed an increase in the shielding of
the carbon of the dithiocarbimate group (S2C@N) in the 13C NMR
spectra, the increase of the wavenumber of the mC@N in the IR spec-
tra and the shortening of the N@C bond with respect to the corre-
sponding data for the free ligands. Semiempirical quantum
chemical calculation confirmed the charge distribution and the
bond characteristics initially suggested by the spectroscopic exper-
iments. The charge distribution in S2C@N group before and after the
complexation are in accord with the spectroscopic and crystallo-
graphic data and confirm the increase of the importance of the
canonical structure (c) in complexes 1–5 when compared to the par-
ent potassium dithiocarbimates. The complexes showed interesting
inter and intramolecular interactions. Especially rare cases of C-
HꢀꢀꢀNi short contact interactions were observed in 1–5 complexes
involving one of the ortho-hydrogen atoms of the aromatic rings of
the phosphines 1–4 and two ortho-hydrogens in the compound 5.
Compound 3 presented the shorter CHꢀꢀꢀNi distance (2.68 Å).
C15–HꢀꢀꢀNi intramolecular interactions with distances between
2.68 and 2.85 Å (angles 117.9–123.8o) were observed in com-
pounds 1–5. These are rare cases of short contact interactions in
planar d8 systems [6,7,26]. Interactions characterized by MꢀꢀꢀH dis-
tances between 2.3 and 2.9 Å might be important for catalytic
applications [26]. Compound 3 presented the shorter CHꢀꢀꢀNi dis-
tance (2.68 Å) as shown in Table 4.
The semiempirical quantum chemical calculations reproduced
correctly the crystallographic structure, showing a small root mean
square deviation (RMSD) as displayed in Table 5. Dihedral angles
analysis showed that complexes conformations are affected by
the presence of the halogen, independently of the physical state
of theses compounds. The complexes 2 and 3 (crystallized in the
monoclinic system) presented greater RMSD. These high correla-
tions between theoretical and experimental results suggest that
the quantum chemical calculations can be used to describe the
electronic structure of the studied complexes.
Acknowledgements
The authors gratefully acknowledges financial support from
CNPq and FAPEMIG.
We have related the decrease of the distance of the C@N bond of
dithiocarbimate metal complexes when compared to free ligands
to the raise in the importance of the canonical form (c) upon com-
plexation (Scheme 2) [8–10]. The shift of the signal of C1 to higher
fields in the 13C NMR, and the increase of the wavenumber of the
Appendix A. Supplementary material
CCDC 812069, 812070, 812071, 812072 and 812073 contain the
supplementary crystallographic data for complexes 1, 2, 3, 4 and 5,

244
M.R.L. Oliveira et al. / Inorganica Chimica Acta 376 (2011) 238–244
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[12] K. Hartke, Archiv der Pharmazie 299 (1966) 164.
respectively. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.ica.2011.
06.025.
[13] H.U. Hummel, U.Z. Korn, Naturforsch B 44 (1989) 24.
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Enzymology, vol. 276, Academic Press, New York, 1997, p. 307.
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