Syntheses, crystal structure and spectroscopic characterization of novel 1,2-bis(diphenylphosphine)ethane(N-R-sulfonyldithiocarbimato)nickel(II) complexes

Article abstract of DOI:10.1016/j.poly.2007.11.001

Three new complexes of the general formula: [Ni(RSO₂N{double bond, long}CS₂)(dppe)], where R = CH₃ (1), CH₃CH₂ (2), 2-CH₃C₆H₄ (3) and dppe = 1,2-bis(diphenylphosphine)ethane, were obtained in crystalline form by the one-pot reaction of the appropriate potassium N-R-sulfonyldithiocarbimate: RSO₂N{double bond, long}CS₂K₂ · 2H₂O and 1,2-bis(diphenylphosphine)ethane with nickel(II) chloride hexahydrate in ethanol/water mixture. The complex 1 forms monoclinic crystals (P2₁/c) with two molecules in the asymmetric unit (Z = 8), while the crystals of the complexes 2 and 3 are orthorhombic, Pbca (Z = 8) and P2₁2₁2₁ (Z = 4) respectively, with one molecule in the asymmetric unit. All complexes present a distorted square-planar environment around the Ni atom. The elemental analyses and the IR, ¹H NMR, ¹³C NMR and ³¹P NMR spectra are consistent with the formation of the nickel(II) complexes with mixed ligands.

Full text of DOI:10.1016/j.poly.2007.11.001

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 727–733
www.elsevier.com/locate/poly
Syntheses, crystal structure and spectroscopic characterization
of novel 1,2-bis(diphenylphosphine)ethane-
(N-R-sulfonyldithiocarbimato)nickel(II) complexes
a,
a
a
b
Marcelo R.L. Oliveira *, Jorge Amim Jr , Ivan A. Soares , Vito M. De Bellis ,
c
d
d
Carlos Alberto de Simone , Celice Novais , Silvana Guilardi
a
Departamento de Quı´mica, Universidade Federal de Vic¸osa, Vic¸osa MG, CEP 36571-000, Brazil
b
ˆ
Departamento de Quı´mica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Belo Horizonte MG, CEP 31270-901, Brazil
c
Departamento de Quı´mica, Universidade Federal de Alagoas, Maceio´ AL, CEP 57072-970, Brazil
d
ˆ ˆ
Instituto de Quı´mica, Universidade Federal de Uberlandia, Uberlandia MG, CEP 38408-100, Brazil
Received 26 July 2007; accepted 1 November 2007
Abstract
Three new complexes of the general formula: [Ni(RSO2N@CS2)(dppe)], where R = CH3 (1), CH3CH2 (2), 2-CH3C6H4 (3) and
dppe = 1,2-bis(diphenylphosphine)ethane, were obtained in crystalline form by the one-pot reaction of the appropriate potassium
N-R-sulfonyldithiocarbimate: RSO2N@CS2K2 Æ 2H2O and 1,2-bis(diphenylphosphine)ethane with nickel(II) chloride hexahydrate in
ethanol/water mixture. The complex 1 forms monoclinic crystals (P21/c) with two molecules in the asymmetric unit (Z = 8), while the
crystals of the complexes 2 and 3 are orthorhombic, Pbca (Z = 8) and P212121 (Z = 4) respectively, with one molecule in the asymmetric
1
unit. All complexes present a distorted square-planar environment around the Ni atom. The elemental analyses and the IR, H NMR,
13C NMR and 31P NMR spectra are consistent with the formation of the nickel(II) complexes with mixed ligands.
ꢀ 2007 Elsevier Ltd. All rights reserved.
Keywords: Dithiocarbimates; 1,2-bis(Diphenylphosphine)ethane; Nickel complexes; Crystal structure
1. Introduction
and PR3 (R = alkyl/aryl) [6]. Nickel(II) dithiocarbamates
normally react with phosphines to form complexes with
the NiS2P2 chromophore [7–12].
Dithiocarbamate derivatives show a wide range of appli-
cations. For example, they are very active accelerators in
vulcanization [1–3] and many dithiocarbamates, anions
and complexes, show biological activity and are used as
fungicides [1,4].
Many authors have investigated complexes of nickel(II)
with diphosphines. These systems are quite attractive in
view of their importance as precursors in catalytic reactions
[5]. Complexes containing the NiXS2P chromophore
(X = halide, S2 = dithiocarbamate, P = phosphine) are
usually obtained by reacting NiX2 with dithiocarbamates
Some nickel complexes with dithiocarbimates and
phosphines with general formulae [Ni(R0N@CS2)(PR3)2]
(R and R0 = alkyl/aryl) have been obtained [13]. However,
only the nickel complexes with general formulae [Ni-
(RSO2N@CS2)(PPh3)2] with R = 2-CH3C6H4, 4-CH3C6H4
and 4-BrC6H4 [14] and with R = 2,5-Cl2C6H3 [15] have
had their structures determined by X-ray diffraction
techniques.
We decided to study dithiocarbimato complexes due to
their similarities with the dithiocarbamate compounds.
As part of these studies three new nickel(II)-dithiocarbi-
mato-diphosphine complexes of the general formula:
[Ni(RSO2N@CS2)(dppe)], where R = CH3 (1), CH3CH2
*
Corresponding author. Tel.: +55 31 3899 3059; fax: +55 31 3899 3065.
E-mail address: marcelor@ufv.br (M.R.L. Oliveira).
0277-5387/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.11.001

728
M.R.L. Oliveira et al. / Polyhedron 27 (2008) 727–733
(2), 2-CH3C6H4(3) and dppe = 1,2-bis(diphenylphosphine)-
ethane, were obtained in crystalline form by the reaction
of NiCl2 Æ 6H2O with the diphosphine and dithiocarbimate
anions derived from sulfonamides. The complexes here
studied are the first examples of nickel(II)–sulfonyldithio-
carbimato–diphosphine complexes prepared and characte-
rized by single crystal X-ray diffraction techniques. The
distilled water and ethanol, and dried under reduced pres-
sure for one day yielding [Ni(RSO2N@CS2)(dppe)] (ca.
70%). Suitable crystals for X-ray structure analysis were
obtained after slow evaporation of solutions of the com-
pounds in dichloromethane/ethanol and few drops of
water.
1
compounds were also characterized by IR, H, 13C and
2.2.1. [Ni(CH3SO2N@CS2) (dppe)] (1)
31P NMR and elemental analyses for C, H, N and Ni.
Elemental Anal. Calc. C, 53.69; H, 4.34; N, 2.24; Ni,
9.37. Found C, 53.41; H, 4.46; N, 2.26; Ni, 9.40%. M.p.
with decomposition (ꢁC): 227.3–229.5. IR (most important
bands) (cmꢀ1): 1463 m(C@N); 1283 mass (SO2); 1128 msym
(SO2); 923 mass (CS2) and 374 m(NiS). 1H NMR (d), J
(Hz): 7.79–7.69 (m, 8H, H2 and H6 of the aromatic rings);
7.56–7.43 (m, 12H, H3, H4 and H5 of the aromatic rings);
3.03 (s, 3H, CH3) and 2.36 (d, 4H, JHP = 17, CH2CH2).
13C{1H} NMR (d), J(Hz): 198.67 (N@CS2); 42.05 (CH3).
dppe signals: 132.91 (t, JCP = 5.4, C2 and C6); 131.88 (s,
C4); 129.41 (t, JCP = 5.2, C3 and C5); 128.23 (t,
JCP = 23, C1); 26.10 (t, JCP = 23, CH2CH2). 31P NMR
(300 K) (d): 57.31 (s). 31P NMR (240 K) (d), J (Hz):
58.62 (d, JPP = 40.5, P1); 57.78 (d, JPP = 40.5, P2).
2. Experimental
2.1. Methods and materials
The solvents were purchased from Merck and used
without further purification. The sulfonamides, nickel(II)
chloride hexahydrate and 1,2-bis(diphenylphosphine)eth-
ane were purchased from Aldrich. Carbon disulfide and
potassium hydroxide were purchased from Vetec. The
N-R-sulfonyldithiocarbimate potassium salts dihydrate
were prepared in dimethylformamide from sulfonamides
analogously as described in the literature [16]. Melting
points were determined with a Mettler FP5 equipment.
Microanalyses for C, H and N were obtained from a Per-
kin–Elmer 2400 CHN. Nickel was analysed 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
2.2.2. [Ni(CH3CH2SO2N@CS2)(dppe)] (2)
Elemental Anal. Calc. C, 54.39; H, 4.56 N, 2.19; Ni,
9.17. Found: C, 52.49; H, 4.36; N, 2.09; Ni, 9.00%. M.p.
with decomposition (ꢁC): 217.0–219.0. IR (most important
bands) (cmꢀ1): 1463 m(C@N); 1275 mass (SO2); 1121 msym
(SO2); 920 mass (CS2) and 344 m(NiS). 1H NMR (d), J
(Hz): 7.78–7.72 (m, 8H, H2 and H6 of the aromatic rings);
7.59–7.44 (m, 12H, H3, H4 and H5 of the aromatic rings);
3.12 (q, 2H, J = 7.5 CH2SO2); 2.36 (d, 4H, JHP = 17,
CH2CH2); 1.38 (t, 3H, J = 7.5 CH3). 13C{1H} NMR (d),
J (Hz): 198.32 (N@CS2); 48.65 (CH2SO2); 8.20 (CH3). dppe
signals: 132.88 (t, JCP = 5.7, C2 and C6); 131.81 (s, C4);
129.36 (t, JCP = 5.2, C3 and C5); 128.21 (t, JCP = 21,
C1); 25.94 (t, JCP = 23, CH2CH2). 31P NMR (300 k) (d):
57.18 (s). 31P NMR (240 k) (d),J (Hz): 58.64 (d,
JPP = 40.5, P1); 57.75 (d, JPP = 40.5, P2).
1
KBr pellets and nujol mulls between CsI plates. The H
(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 stan-
dard. Additionally, the 31P (162 MHz) NMR spectra were
recorded at 240 K.
2.2. Syntheses
The compounds were prepared according to the meth-
odology applied for the syntheses of similar compounds
with triphenylphosphine [14] (Scheme 1).
2.2.3. [Ni(2-CH3C6H4SO2N@CS2)(dppe)] (3)
A solution of potassium N-R-sulfonyldithiocarbimate
dihydrate (1.0 mmol) in water (10 mL) was added to a solu-
tion of 1,2-bis(diphenylphosphine)ethane (1.0 mmol) in
ethanol (40 mL). Nickel(II) chloride hexahydrate
(1.0 mmol) was added to the suspension and the reaction
mixture was stirred for 5 h at room temperature. The col-
our of the suspension changed from green to orange/red.
The solid product of the reaction was filtered, washed with
Elemental Anal. Calc. C, 58.13; H, 4.45; N, 1.99; Ni,
8.36. Found: C, 57.40; H, 4.51; N, 1.89; Ni, 8.15%. M.p.
with decomposition (ꢁC): 230.0–232.0. IR (most important
bands) (cmꢀ1): 1459 m(C@N); 1304 mass (SO2); 1151 msym
(SO2); 919 mass (CS2) and 357 m(NiS). 1H NMR (d),
J(Hz): 8.04 (d, J = 7.6, 1H, H6 of the aromatic ring of
the dithiocarbimato) 7.76–7.67 (m, 8H, H2 and H6 of the
aromatic rings of dppe); 7.51–7.41 (m, 12H, H3, H4 and
NiCl2.6H2O, dppe
[Ni(RSO
2N=CS2)dppe]
RSO2N=CS2K2.2H2O
-
-
8H2O, 2KCl
H2O/EtOH;
1, 2, 3
1 (R = CH3), 2 (R = CH3CH2), 3 (R = 2-CH3C6H4)
Scheme 1. Syntheses of 1–3.

M.R.L. Oliveira et al. / Polyhedron 27 (2008) 727–733
729
H5 of the aromatic rings of dppe); 7.36–7.28 (m, 1H, H5 of
the aromatic ring of the dithiocarbimato); 7.20–7.13 (m,
2H, H3 and H4 of the aromatic ring of the dithiocarbi-
mato); 2.68 (s, 3H, CH3); 2.33 (d, 4H JHP = 17, CH2CH2).
13C{1H} NMR (d), J (Hz): 198.26 (N@CS2); 140.80 (C1);
137.98 (C2); 131.69 (C4); 128.55 (C5); 125.19 (C6). dppe
signals: 132.90 (t, JCP = 5.4, C2 and C6); 131.78 (s, C4);
129.36 (t, JCP = 5.2, C3 and C5); 128.35 (t, JCP = 23,
C1); 25.89 (t, JCP = 23, CH2CH2). 31P NMR (300 k) (d):
56.80 (s). 31P NMR (240 k) (d), J (Hz): 58.10 (d,
JPP = 40.5, P1); 57.43 (d, JPP = 40.5, P2).
grams [18]. Numerical absorption correction (GAUSSIAN)
were applied using the program SORTAV [19].
The structures were solved by direct methods with SHEL-
XS-97 [20]. The models were refined by full-matrix least
squares on F2 using SHELXL-97 [21]. All the hydrogen atoms
were stereochemically positioned and refined with the rid-
ing model [21]. Data collections and experimental details
for the compounds are summarized in Table 1. The pro-
gram ORTEP-3 [22] was used for graphic representation
and the program WINGX [23] to prepare materials for pub-
lication. Selected bond and angles are presented in Table 2.
2.3. X-ray crystallography
3. Results and discussion
X-ray diffraction data collections for all crystals were
performed on an Enraf-Nonius Kappa-CCD diffractome-
ter (95 mm CCD camera on j-goniostat) using graphite
The complexes are quite stable at ambient conditions.
They are soluble in acetonitrile, dimethylformamide,
dimethylsulfoxide, chloroform and dichloromethane, and
insoluble in water, methanol and ethanol. There are no
strong or medium bands in the 1400–1600 cmꢀ1 region in
the IR spectra of the potassium dithiocarbimates related
to the complexes 1–3, their mC@N band being observed in
the 1300–1260 cmꢀ1 region [24,25]. These low values point
to a great contribution of the canonical forms (a) and (b)
for the resonance hybrid of the dithiocarbimate anions
(Scheme 2). In the spectra of the bis(dithiocarbimato)
˚
monochromated Mo Ka radiation (0.71073 A), at room
temperature for the complex 2 and at lower temperature
for the complexes 1 and 3. Data collections were carried
out using the COLLECT software [17] up to 50ꢁ in 2h with
a redundancy of four. Final unit cell parameters were based
on all reflections. Integration and scaling of the reflections,
correction for Lorentz and polarization effects were per-
formed with the HKL DENZO-SCALEPACK system of pro-
Table 1
Crystal data and structure refinement for the complexes 1–3
Complex
1
2
3
Empirical formula
Formula weight (g molꢀ1
Temperature (K)
C28H27NNiO2P2S3
623.34
210(2)
C29H29NNiO2P2S3
640.36
293(2)
C34H31NNiO2P2S3
702.43
210(2)
)
Crystal dimensions (mm)
Crystal system
Space group
Unit cell dimensions
0.310 · 0.270 · 0.140
monoclinic
P21/c
0.388 · 0.177 · 0.014
orthorhombic
Pbca
0.407 · 0.149 · 0.117
orthorhombic
P212121
˚
a (A)
19.3341(2)
19.1118(4)
15.9462(3)
104.697(1)
5699.48(17)
8 (Z0 = 4)
1.46
16.1991(8)
15.1391(4)
23.5503(12)
12.4023(3)
12.8866(2)
20.1779(5)
˚
b (A)
˚
c (A)
b (ꢁ)
Volume (A )
3
˚
5775.5(4)
8
1.473
1.028
2656
3224.9(1)
4
1.447
0.928
1456
Z
Calc. density (mg mꢀ3
l (Mo Ka) (mmꢀ1
F(000)
)
)
1.04
2592
Transmission factors: minimum, maximum
h Range for data collection (ꢁ)
Index range
0.739, 0.864
2.13–27.5
ꢀ25 6 h 6 22,
ꢀ22 6 k 6 24,
ꢀ18 6 l 6 20
35271
0.826, 0.986
2.98–25.69
ꢀ19 6 h 6 16,
ꢀ14 6 k 6 18,
ꢀ28 6 l 6 28
36401
0.803, 0.900
1.88–27.44
ꢀ13 6 h 6 16,
ꢀ15 6 k 6 16,
ꢀ23 6 l 6 26
20282
Reflections collected
Independent reflections [Rint
Reflections I > 2r(I)
]
13017 [0.0382]
9739
5476 [0.1398]
2901
7322 [0.0445]
6169
Number of parameters refined
667
345
388
Final R for I > 2r(I)
R1 = 0.0388
wR2 = 0.0779
R1 = 0.0628,
wR2 = 0.0878
1.011
R1 = 0.0460
wR2 = 0.0774
R1 = 0.1285
wR2 = 0.0961
0.924
R1 = 0.0361
wR2 = 0.0793
R1 = 0.0479
wR2 = 0.0841
1.033
R indices [all data]
Goodness-of-fit on F2
Residual electron density (e A
ꢀ3
˚
)
0.395
0.481
0.332

730
M.R.L. Oliveira et al. / Polyhedron 27 (2008) 727–733
Table 2
in the free ligands and in the analogous bis(dithiocarbi-
mato) complexes spectra. This effect is also observed, for
example, when the spectrum of the complex [Ni(dpdtc)2]
(dpdtc = N,N-propyldithiocarbamato) (mC@N band is
observed in 1508 cmꢀ1) is compared with the spectrum of
˚
Selected bond (A) and angles (ꢁ) for the complexes 1–3
1
2
3
Molecule 1
Molecule 2
Bond length
Ni–S1
Ni–S2
Ni–P1
Ni–P2
P1–C9
P1–C15
P1–C33
P2–C21
P2–C27
P2–C34
C1–S1
C1–S2
C1–N
[Ni(dpdtc)(dppe)]+ (mC@N band is observed in 1526 cmꢀ1
)
2.1959(7)
2.1978(7)
2.1562(7)
2.1773(7)
1.810(3)
1.816(3)
1.834(3)
1.827(3)
1.813(2)
1.842(2)
1.747(2)
1.742(2)
1.286(3)
1.638(2)
1.430(2)
1.429(2)
1.757(3)
2.1966(6)
2.1979(7)
2.1569(7)
2.1466(6)
1.821(2)
1.814(2)
1.840(2)
1.813(2)
1.823(2)
1.841(2)
1.744(2)
1.738(2)
1.296(3)
1.635(2)
1.418(2)
1.433(2)
1.740(3)
2.201(1)
2.203(1)
2.171(1)
2.166(1)
1.822(4)
1.818(3)
1.823(4)
1.817(4)
1.811(4)
1.835(4)
1.761(4)
1.745(4)
1.287(4)
1.640(3)
1.445(3)
1.441(3)
1.761(4)
1.530(5)
1.521(5)
2.1822(7)
2.2065(8)
2.1718(7)
2.1672(7)
1.812(3)
1.818(3)
1.834(3)
1.821(3)
1.819(3)
1.844(3)
1.749(3)
1.745(3)
1.280(3)
1.641(2)
1.426(2)
1.444(2)
1.776(3)
1.386(4)
1.526(4)
[11]. The mC–S band were observed at higher frequency in
the spectra of the potassium salts of dithiocarbimates
(960–940 cmꢀ1) [24,25] than in the spectra of the complexes
here studied (925–915 cmꢀ1), and in the spectra of analo-
gous bis(dithiocarbimato) complexes (940–925 cmꢀ1) [25–
27]. This band appears without any splitting, confirming
the bidentate coordination of the dithiocarbimate moiety.
The shifts observed in the mC–S in the spectra of the com-
plexes are also consistent with the increased importance
of the canonical form (c) after complexation (Scheme 2).
The spectra of the complexes also show the expected med-
ium band in the 300–400 cmꢀ1 range assigned to the NiS
vibrations [28]. The mNiP bands was not observed above
N–S3
O1–S3
O2–S3
C2–S3
C2–C3
C33–C34
200 cmꢀ1
.
The NMR spectra of 1–3 were typical for diamagnetic
1.521(4)
1.530(3)
species supporting the assumption of a square planar
geometry around the nickel atom. The H NMR spectra
Bond angles
S1–Ni–S2
P1–Ni–P2
S1–Ni–P1
S2–Ni–P2
Ni–P1–C33
Ni–P2–C34
S1–C1–S2
S1–C1–N
S2–C1–N
C1–N–S3
N–S3–O1
N–S3–O2
O1–S3–O2
N–S3–C2
O1–S3–C2
O2–S3–C2
S3–C2–C3
C9–P1–C15
C21–P2–C27
1
79.14(2)
86.52(3)
96.44(3)
98.89(3)
109.19(9)
109.14(9)
106.7(1)
132.4(2)
120.8(2)
121.3(2)
112.4(1)
109.8(1)
117.5(2)
99.3(1)
79.96(2)
88.47(2)
96.74(2)
95.52(2)
109.09(8)
108.89(8)
108.4(1)
130.6(2)
121.0(2)
120.2(2)
113.7(1)
108.7(1)
116.4(2)
99.6(1)
79.33(4)
86.40(4)
99.31(4)
95.27(4)
79.21(3)
86.69(3)
97.78(3)
96.32(3)
of the complexes showed the signals for the hydrogen
atoms of the dppe and the dithiocarbimate moiety. The
integration curves on the 1H NMR spectra were consistent
with a 1:1 proportion between the dppe and the dithiocarb-
imate anion. The signals in the spectra of the free dithio-
carbimates [24,25] and in the spectra of the complexes
show approximately the same chemical shifts. Neverthe-
less, the N@CS2 (C1) signal is shifted in the spectra of
the complexes to higher field if compared to the spectra
of the free ligands [24,25] and the correspondent bis(dith-
iocarbimato) complexes [Ni(RSO2N@CS2)2]2ꢀ [25–27]. If
the canonical form (c) (Scheme 2) is more important for
the complexes than for the ligands, then the C1 carbon
atom is expected to be more shielded in the complexes here
studied.
107.8(1)
109.7(1)
106.6(2)
131.5(3)
121.8(3)
121.0(3)
113.1(2)
109.8(2)
116.2(2)
99.8(2)
107.6(2)
108.9(2)
110.2(3)
106.4(2)
106.8(2)
106.3(1)
109.9(1)
106.4(1)
132.2(2)
121.4(2)
124.0(2)
105.8(1)
107.9(1)
117.4(1)
109.4(1)
109.0(1)
107.2(1)
117.3(2)
104.3(1)
106.7(1)
108.0(2)
108.6(2)
108.8(2)
108.2(2)
107.6(1)
109.3(1)
105.8(1)
105.6(1)
Most of the diphosphine signals in the 13C NMR spectra
appeared as pseudo triplets or doublets. This is consistent
with square planar geometry for the complexes. Doublets
or pseudo triplets are commonly observed in the 13C
NMR spectra of bis(phosphine) transition metal cis-com-
plexes [14,29]. The 31P NMR spectra exhibited only one
signal (ca. 58 d) at 300 K, but the signal split into two dou-
blets due P–P coupling at 240 K confirming that the phos-
phorus atoms in the molecules are not magnetically
equivalent. Significant changes in the phosphorus chemical
shifts in the spectra of the complexes when compared to
complexes [Ni(RSO2N@CS2)2]2ꢀ (R = CH3, CH3CH2 and
2-CH3C6H4) this band is observed in the 1400–1360 cmꢀ1
region [25–27]. A strong band observed in the 1470–
1450 cmꢀ1 region in the spectra of the complexes 1–3 was
assigned to the mC@N. The mesomeric drift of electrons
from the dithiocarbimate moiety towards the metal centre
increases the contribution of the canonical form (c)
(Scheme 2). This is reflected in the shift in mC@N values to
higher wavenumbers when compared with those observed
_
_
_
_
N
S
S
S
S
_
N
S
S
RSO2
C
RSO2
N
c
C
RSO2
C
_
a
b
Scheme 2. Three canonical forms for N-R-sulfonyldithiocarbimate anion.

M.R.L. Oliveira et al. / Polyhedron 27 (2008) 727–733
731
that of the free diphosphine (ca. ꢀ12 d) [5] are caused by
the nickel atom that deshields the phosphorus atoms con-
siderably. Similar chemical shifts are also observed in the
spectra of many complexes with NiX2(P–P) chromophores
(P–P = 1,2-bis(diphenylphosphine)ethane; X = Cl, Br, I, S)
[5,8–12].
The ORTEP-3 view [22] of the solid-state molecular struc-
tures of the complexes 1, 2 and 3 are illustrated in Figs. 1–
3. Compound 1 crystallizes in the monoclinic system, space
group P21/c, with two independent molecules in asymmet-
ric unit (Z = 8), while the complexes 2 and 3 crystallize in
the orthorhombic system, space groups Pbca (Z = 8) and
P212121 (Z = 4), respectively.
The Ni–S bonds, in complexes 1 and 2 are symmetric. In
3, this bond exhibits a small asymmetry, probably due to
the repulsive interaction between the S1 atom and the large
RSO2 group. This group, in all complexes, is in cis position
in relation to the S1 atom. The orientation of the RSO2
group is also responsible for the difference between the
angles S1–C1–N and S2–C1–N.
The C–S bond lengths in complexes 1–3 (ca. 1.74) are
characteristic of partial double bonds (typical bond
˚
˚
lengths: 1.81 A for C–S and 1.69 A for C@S). The C–N
bond distances (ca. 1.285) are similar to that of the double
˚
bond C@N (1.275–1.300 A) [30,31]. This behavior indi-
cates that the p electron density is delocalized over
S2CN moiety. The CN bonds in these neutral complexes
are shorter than in the bis(dithiocarbimato) complexes
(Table 3) [25–27].
The crystallographic data are in accord with the spectro-
scopic data (Table 3). Both point to an increase on the
contribution of the canonical form (c) (Scheme 2) in this
sequence: free ligands < bis(dithiocarbimato) complexes <
complexes 1–3 complexes.
The R-group in complex 3 lies in a significantly different
conformation from that observed for the other complexes.
The C1–N–S3–C2 torsion angle is 41.8(3)ꢁ for the complex
3, 164.2(2)ꢁ for the molecule 1 and ꢀ172.0(2)ꢁ for the mol-
ecule 2 of the complex 1 and 157.0(3)ꢁ for the complex 2.
The P–Csp3 and Csp3–Csp3 distances in the dppe ligand,
in all complexes, are similar to Ni(II) complexes with
Ni(S–S)(P–P) chromophores [9,32–34]. The bond lengths
and angles in the phenyl rings are in good agreement,
In all complexes, the nickel cation is coordinated by the
two sulfur atoms of the dithiocarbimato ligand and by two
phosphorus atoms of the 1,2-bis(diphenylphosphine)ethane
into a distorted square-planar geometry. The P1–Ni–S1
and P2–Ni–S2 angles are more distorted from 90ꢁ than
the P1–Ni–P2 angles. The S1–Ni–S2 angle is considerably
smaller than 90ꢁ due to the chelation of the N-R-sul-
fonyldithiocarbimato ligand forming a four membered ring
(NiS2C). When the complex [Ni(2-CH3C6H4SO2N@CS2)-
(PPh3)2] [14] is compared with 3, some interesting differ-
ences can be observed due to the chelation of dppe and
its smaller steric effect. The P–Ni–P angle in 3 (86.69ꢁ) is
smaller than in [Ni(2-CH3C6H4SO2N@CS2)(PPh3)2]
(98.48ꢁ). The S–Ni–S angle in 3 (79.21ꢁ) is greater than in
the bis(triphenylphosphine) complex (77.87ꢁ) and the Ni–
˚
P bond length in 3 (ca. 2.17 A) is smaller than Ni–P bond-
˚
ing in the bis(triphenylphosphine) complex (ca. 2.21 A).
Fig. 1. The molecular structure of 1. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.

732
M.R.L. Oliveira et al. / Polyhedron 27 (2008) 727–733
Fig. 2. The molecular structure of 2. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.
Table 3
Comparison between selected crystallographic and spectroscopic data for
the CN moiety in the complexes 1–3 and related compounds
Compounds
CN length mCN
(A)
13C NMR
(d)
(cmꢀ1
)
˚
CH3SO2N@CS2Ka2
1260
1390
1463
223
210
199
(Bu4N)2[Ni(CH3SO2N@CS2)2]b
[Ni(CH3SO2N@CS2)dppe] (1)
1.31(2)
1.296(3);
1.286(3)
CH3CH2SO2N@CS2K2c
1300
1399
1463
1280
1365
1459
224
209
198
223
209
198
(Bu4N)2[Ni(CH3CH2SO2N@CS2)2]c
[Ni(CH3CH2SO2N@CS2)dppe] (2)
2-CH3C6H4SO2N@CS2K2a
1.309(2)
1.287(5)
(Bu4N)2[Ni(2-CH3C6H4SO2N@CS2)2]d 1.311(3)
[Ni(2-CH3C6H4SO2N@CS2)dppe] (3)
1.280(3)
a
Ref. [24].
Ref. [27].
Ref. [25].
Ref. [26].
b
c
d
the ethane group and oxygen, with donor-acceptor dis-
tances ranged from 3.209 to 3.405 A. The complex 2 have
Fig. 3. The molecular structure of 3. Displacement ellipsoids are drawn at
the 30% probability level. H atoms have been omitted for clarity.
˚
another weak interaction [C18–H18. . .O2 (ꢀx, ꢀy + 1,
˚
within experimental accuracy, with the values found in the
literature [30].
ꢀz)] with C. . .O of 3.409 A and the complex 1 have two
more intermolecular interactions C–H. . .O involving the
The angles between the planes of the phenyl rings on
each phosphorus, P1 and P2 are, respectively: 82.9(1)ꢁ
and 52.19(8)ꢁ (molecule 1) and 63.4(1)ꢁ and 61.50(9)ꢁ (mol-
ecule 2) in complex 1, 69.7(1)ꢁ and 76.4(1) in complex 2 and
87.3(1)ꢁ and 68.5(1)ꢁ in complex 3. In all complexes there
are weak intermolecular interactions among C33 atom of
carbon atom of the CH3SO2 group.
4. Conclusion
Three novel 1,2-bis(diphenylphosphino)ethane(N-R-sul-
fonyldithiocarbimato)nickel(II) complexes were prepared

M.R.L. Oliveira et al. / Polyhedron 27 (2008) 727–733
733
and characterized by IR, 1H, 13C and 31P NMR, elemental
analyses for C, H, N, Ni and by single crystal X-ray diffrac-
tion techniques. They are the first examples of nickel(II)
complexes with the mixed ligands N-R-sulfonyldithiocarb-
imate and diphosphine.
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causes a drift of electrons from the dithiocarbimate to the
metallic center, increasing the contribution of the canonical
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quent increase of the CN double bond character. There-
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The comparison between bis(triphenylphosphine)-N-R-
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Acknowledgements
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This work has been supported by CNPq, CAPES, FAP-
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Appendix A. Supplementary material
CCDC 653767, 653768 and 653766 contain the supple-
mentary crystallographic data for 1, 2 and 3. These data
can be obtained free of charge via www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit
@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.poly.2007.11.001.
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