N-(2-hydroxyethyl)-N-methyldithiocarbamato complexes of nickel(II) with phosphorus donor ligands

Article abstract of DOI:10.1002/zaac.200500282

Planar nickel(II) complexes involving N-(2-Hydroxyethyl)-N- methyldithiocarbamate, such as [NiX(nmedtc)(PPh₃)] (X = Cl, NCS; PPh₃ = triphenylphosphine), and [Ni(nmedtc)-(P-P)]ClO₄(P-P = 1,1-bis(diphenylphosphino)methane(dppm); 1,3-bis(diphenylphosphino)propane (1,3-dppp); 1,4-bis(diphenylphosphino)butane(1,4-dppb) have been synthesized. The complexes have been characterized by elemental analyses, IR and electronic spectroscopies. The increased vC-N value in all the complexes is due to the mesomeric drift of electrons from the dithiocarbamate ligands to the metal atom. Single crystal X-ray structure of [Ni(nmedtc)(1,3-dppp)]ClO₄· H₂O is reported. In the present 1,3-dppp chelate, the P-Ni-P angle is higher than that found in 1,2-bis(diphenylphosphino)ethane-nickel chelates and lower than 1,4-bis(diphenylphosphino)butane-nickel chelates, as a result of presence of the flexible propyl back bone connecting the two phosphorus atoms of the complex.

Full text of DOI:10.1002/zaac.200500282

DOI: 10.1002/zaac.200500282
N-(2-Hydroxyethyl)-N-methyldithiocarbamato Complexes of Nickel(II) with
Phosphorus Donor Ligands
A. Manohara, K. Ramalingama,*, R. Thiruneelakandana, G. Bocellib, and L. Righib
a Annamalainagar / India, Department of Chemistry, Annamalai University
b Parma / Italy, Consiglio Nationale Delle Ricerche
Received June 30th, 2005; revised October 5th, 2005.
Abstract. Planar nickel(II) complexes involving N-(2-Hydroxy-
ethyl)-N-methyldithiocarbamate, such as [NiX(nmedtc)(PPh3)]
(X ϭ Cl, NCS; PPh3 ϭ triphenylphosphine), and [Ni(nmedtc)-
[Ni(nmedtc)(1,3-dppp)]ClO4·H2O is reported. In the present
1,3-dppp chelate, the PϪNiϪP angle is higher than that found in
1,2-bis(diphenylphosphino)ethane-nickel chelates and lower than
1,4-bis(diphenylphosphino)butane-nickel chelates, as a result of
presence of the flexible propyl back bone connecting the two phos-
phorus atoms of the complex.
(P-P)]ClO4(P-P
ϭ
1,1-bis(diphenylphosphino)methane(dppm);
1,3-bis(diphenylphosphino)propane (1,3-dppp); 1,4-bis(diphenyl-
phosphino)butane(1,4-dppb) have been synthesized. The complexes
have been characterized by elemental analyses, IR and electronic
spectroscopies. The increased νCϪN value in all the complexes is
due to the mesomeric drift of electrons from the dithiocarbamate
ligands to the metal atom. Single crystal X-ray structure of
Keywords: Dithiocarbamate; Thioureide; 1,3-Bis(diphenylphos-
phino)propane
Introduction
Results and Discussion
Infrared spectra
Important absorptions in the dithiocarbamate complexes
are due to νCϪN and νCϪS stretching modes. The νCϪN
band has been used as a measure of the contribution of
the thioureide form to the structure of the dithiocarbamate
compound. For all the complexes strong bands appeared
around 1500 and 1000 cmϪ1 due to νCϪN (thioureide) and
νCϪS vibrations, respectively. Shift in νCϪN values to
higher wave numbers compared with the parent Ni(dtc)2
complexes is due to the mesomeric drift of electrons from
the dithiocarbamate moiety towards the metal centre, in-
creasing the contribution of the thioureide form. The νCϪS
band appear around 977 cmϪ1 without any splitting sup-
porting the bidentate coordination of the dithiocarbamate
moiety [16]. In addition to νCϪN and νCϪS bands, the
spectra showed strong bands around 1100 and 1434 cmϪ1
Group X dithiolates containing planar MS4 chromophores
show interesting variations in their reaction with Lewis
bases [1, 2]. Soft PdIIand PtII dithiolates preferably interact
with soft phosphines to give rise to planar MS2P2 chromo-
phores [3, 4]. Detailed structural studies on a variety of
MS2P2 chromophores have also been made [5, 6]. The
planar dithiocarbamates prefer to react with soft lewis
bases such as phophines rather than hard nitrogenous bases
such as NH3 and pyridine due to symbiotically induced
softness [7, 8]. Nickel dithiocarbamates in their reaction
with substituted phosphines form planar NiS2P2 chromo-
phores, which are diamagnetic in nature [9Ϫ11]. Synthesis
and single crystal X-ray structural studies on mixed ligand
complexes involving nickel dithiocarbamates and free, che-
lated phosphines such as PPh3, dppe, dppp, dppb were re-
ported from our laboratory [12Ϫ14]. Recently the X-ray
photoelectron (XPS) spectral studies on NiS4, NiS2PCl, and
NiS2P2 chromophores in different nickel complexes have
been reported from our laboratory [15]. XPS studies
showed reduced electron density on NiS2P2 chromophores
and the observation was supported by an earlier cyclic vol-
tammetric study.
Ϫ
Ϫ
due to ClO4 and BPh4 ions, respectively [17]. Important
ir bands and analytical data for the complexes are given in
Table 1. The bands observed at 2093 cmϪ1 in the IR spec-
trum of [Ni(NCS)(nmedtc)(PPh3)] are due to νCϵN and
νCϪS vibrations and indicate that the NCS group is coordi-
nated to nickel through the N atom [18].
Electronic spectra
In all the nickel(II) complexes, bands below 350 nm are due
to intraligand πϪπ* transitions, mainly associated with the
NϪCϭS and SϪCϭS groups. Several authors ascribe
intense bands in the 390Ϫ450 nm region to either metal
Ϫ ligand or ligand Ϫ metal charge transfer [19]. In addition
to these charge transfer bands, the electronic spectra show
* K. Ramalingam
Department of Chemistry,Annamalai University
Annamalainagar Ϫ 608 002, INDIA
email : krauchem@yahoo.com
Z. Anorg. Allg. Chem. 2006, 632, 461Ϫ464
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
461

A. Manohar, K. Ramalingam, R. Thiruneelakandan, G. Bocelli, L. Righi
Table 1 Important IR bands and analytical data for the complexes
Band
Ni%
C%
H%
N%
Complexes
Ϫ
νC-N
νC-S
ClO4
Calcd
Found
Calcd
Found
Calcd
Found
Calcd
Found
Ϫ
/BPh4
Ni (nmedtc)2
[NiCl(nmedtc)(PPh3)]
1523
1531
1528
1550
1537
1531
1532
1542
997
975
998
997
975
997
971
997
Ϫ
Ϫ
Ϫ
1086
1104
1433
1086
1118
16.3
11.6
11.1
7.1
8.5
6.3
16.1
11.4
11.0
6.9
8.4
6.2
26.8
52.2
52.2
57.7
52.0
70.0
51.7
52.3
26.7
52.1
52.0
57.6
51.9
69.9
51.6
52.1
4.5
4.6
4.4
4.6
4.7
5.7
4.8
4.9
4.3
4.4
4.2
4.4
4.5
5.5
4.6
4.7
7.8
2.8
5.3
1.7
2.0
1.5
1.9
1.9
7.6
2.7
5.1
1.5
1.9
1.4
1.6
1.7
[Ni(NCS)(nmedtc)(PPh3)]
[Ni(nmedtc)(PPh3)2]ClO4
[Ni(nmedtc)(dppm)]ClO4
[Ni(nmedtc)(1,2-dppe)]BPh4
[Ni(nmedtc)(1,3-dppp)]ClO4
[Ni(nmedtc)(1,4-dppb)]ClO4
8.1
8.0
8.0
7.8
˚
weak bands at 490 nm and 650 nm are due to the dϪd tran-
sitions. In the case of dialkyldithiocarbamato complexes of
nickel(II), similar bands were reported and these were as-
cribed to transitions from the lower filled d orbital to the
unoccupied dx2Ϫy2 orbital [20]. The two bands at 650 nm
and 490 nm correspond to the dxy Ǟ dx2Ϫy2 and dz2 Ǟ
dx2Ϫy2 transitions. Electronic spectra of free and chelate
phosphine complexes show bands at ca 440, 450, 460, 470,
550 and 570 nm. Strong bands which appear at 440 and
450 nm are attributed to the charge transfer processes [21]
other bands are due to dz2 Ǟ dx2 Ϫy2 (460 and 470 nm),
dxz Ǟ dx2Ϫy2 (550 nm) and dxy Ǟ dx2Ϫy2 (570 nm)
transitions. Similar transitions were reported for
[Ni(dedtc)(PPh3)2]ϩ complex based on a single crystal pola-
rized spectral study [21].
pared to a long NiϪP bond length (2.40 A) reported in the
literature [22]. Interestingly, P(5)ϪNiϪP(4) angle (96.5(2)°)
in the present compound is larger than the angle observed
in 1,2-bis(diphenylphosphino)ethane-nickel chelate [12]. In-
crease in the PϪNiϪP angle in the present complex is as a
result of the presence of flexible long alkyl chain connecting
the two phosphorous atoms. A similar trend was found in
1,4-dppb chelate [14]. The S(2)ϪNi1ϪS(3) bite angle
(79.33(3)°) is normal as found in the parent dithiocarba-
˚
mate complex. The CϪN distance is 1.286(1) A which is
significantly different from that in the parent dithiocarba-
mate, indicating a mesomeric drift of electrons from the di-
thiocarbamate ligand towards the metal atom. A similar
trend was observed in dppe analogue [12]. The CϪN (mean
˚
1.457(2) A) bond lengths in the methyl and ethanolic
groups are in the range of single bond lengths, which con-
trasts well with the short thioureide NϪC bond. The related
CϪS distances are symmetric. Other bond parameters of
the dithiocarbamate moiety are normal.
Single crystal X-ray structure
ORTEP plot of [Ni(nmedtc)(1,3-dppp)]ClO4·H2O complex
is shown in Figure 1. The complex is a monomer. The mol-
ecule is planar in keeping with the observed diamagnetism.
The two NiϪS bonds 2.202(2), 2.197(2) A are not different
though the two NiϪP distances 2.185(2), 2.170(2) A are dif-
A comparison of bond parameters for related com-
pounds is given in Table 2. In the present chelate, the NiϪS
distances are not different, whereas in the 1,2-dppe chelate
the NiϪS distances are significantly different. In both the
chelates, the NiϪP distances are significantly different.
PϪNiϪP angle in the present chelate is higher than that
found in 1,2-bis(diphenylphosphino)ethane-nickel chelates
and lower than propyl back bone connecting the two phos-
phorus atoms of the complex. A similar 1,4-bis(diphenyl-
phosphino)butane-nickel chelates, as a result of presence of
the flexible trend was observed in 1,4-dppb chelate [14]. The
CϪN distance in the present 1,3-dppp chelate is similar to
that found in 1,2-dppe chelate. This decreasing trend in
both chelates, compared with other 1,3-dppp, 1,4-dppb che-
lates and parent dithiocarbamates, is due to the mesomeric
drift of electrons from the dithiocarbamate ligands towards
the metal centre. The oxygen atom of the water molecule
˚
˚
ferent. The observed NiϪP distance is relatively short com-
˚
was at a distance of 1.381 A from the hydroxyl O(10) atom.
Extensive disorder was observed with respect to perchlor-
ate anion, OϪCl distances and the OϪClϪO angles showed
large variations in their values as observed in similar com-
pounds reported from our laboratory [14]. The chlorine
˚
atom of the perchlorate was at 5.699 A from the nickel atom
and the shortest O···O non-bonded distance between highly
˚
Fig. 1 ORTEP plot of the cation of [Ni(nmedtc)(1,3-dppp)]ClO4·H2O
462 zaac.wiley-vch.de
disordered O(2B) and O(10) was observed to be 2.580 A.
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 461Ϫ464

N-(2-Hydroxyethyl)-N-methyldithiocarbamato Complexes of Nickel(II) with Phosphorous Donor Ligands
˚
Table 2 Comparison of bond distances /A and angles /°
Complex
Ni-S(1)
Ni-S(2)
Ni-P(1)
Ni-P(2)
C-N
P(1)-Ni-P(2)
S-Ni-S
Ref.
Ni(deadtc)2
2.209(1)
2.218(3)
2.202(2)
2.212(1)
2.193(1)
2.195(4)
2.197(2)
2.216(1)
Ϫ
Ϫ
1.319(5)
1.28(2)
1.286(1)
1.304(4)
Ϫ
79.3(1)
79.4(1)
79.33(3)
78.3(7)
[27]
[12]
This work
[14]
[Ni(nmedtc)(dppe)]ϩ
[Ni(nmedtc)(1,3-dppp)]ϩ
[Ni(mdtc)(1,4-dppb)]ϩ
2.175(3)
2.185(2)
2.201(1)
2.163(3)
2.170(2)
2.195(1)
86.6(1)
96.5(2)
101.4(8)
Experimental Section
Table 3 Crystal data,data collection, and refinement parameters
for [Ni(nmedtc)(1,3-dppp)]ClO4·H2O
All the reagents and solvents employed were commercially available
high-grade purity materials (E-merck) used as supplied without
further purification. The nickel was estimated by complexometric
titration with murexide as indicator. Elemental analyses (C,H,N)
were carried out with an Heraeus Carlo Erba 1108 instrument. The
complexes were tested qualitatively with Faraday balance for their
magnetic property and all of them were found to be diamagnetic.
IR spectra were recorded on a JASCO IR-700 spectrophotometer
(range 4000 Ϫ 400 cmϪ1) as KBr pellets. The UV-Visible spectra in
CH2Cl2 were recorded on a JASCO-UVIDEC 340 double beam
spectrophotometer.
Empirical formula
Formula weight
Temperature
Crystal System,
Space group
C31H36NO6ClP2S2Ni
738.828
293 K
monoclinic
P21/n
a ϭ 14.933(2) A
b ϭ 21.263(3) A
c ϭ 10.552(3) A
˚
˚
˚
Unit cell dimensions
β ϭ 90.51(4)°
3
˚
Volume
3350.34 A
Z
4
Calculated density
F(000)
λ/A
Crystal Size
θ range / °
Scan type
1.457 g/cm3
1528.0
Mo Ϫ Kα(0.71069)
0.21ϫ0.23ϫ0.31
3-70
ωϪ2θ
˚
Preparation
Index range
Ϫ18 Յ h Յ 18, 0 Յ k Յ 25, 0 Յ l Յ 12
[NiX(nmedtc)(PPh3)](X؍Cl, NCS)
Reflections Collected / Unique 12505/2364 [R(int)ϭ0.059]
Weighing Scheme
Final R, Rw (obs.data)
Goodness of fit
w ϭ 1/[σ2Fo2ϩxP2] x ϭ 0.185
0.066, 0.2592
1.06
A
mixture of Ni(nmedtc)2 (1 mmol), PPh3 (1 mmol) and
NiX2·nH2O (1 mmol) in MeOH-CH2Cl2 (2:1, 75 cm3) was refluxed
for about 3 hours. The precipitated purple red compound was fil-
tered and dried over anhydrous calcium chloride. Complexes were
recrystallized from CH2Cl2-MeOH solvent mixture (yield: 70 %).
Crystallographic data for the structure have been deposited with the
Cambridge Crystallographic Data Centre (CCDC 194889) copies of the data
can be obtained free of charge on application to the Director, CCDC 12
Union Road, Cambridge CB2 1EZ, UK (Fax: intcode ϩ(1223)3 36-033:
e-mail: teched@chemcrys.cam.ac.uk)
[Ni(nmedtc)(P-P)]ClO4(P-P ؍ dppm, dppp, dppb)
A mixture of Ni(nmedtc)(1 mmol), 1,3-bis(diphenylphosphino)pro-
pane (1 mmol), NiCl2·6H2O (0.5 mmol) and NaClO4 (1 mmol) in
MeCNϪMeOH (2:1, 75 cm3) was refluxed for about 3 hours. Re-
sulting red orange solution was filtered and was left for evapor-
ation. For [Ni(nmedtc)(1,3-dppp)]ClO4·H2O, it was possible to ob-
tain a single crystal appropriate for X-ray analysis. The remaining
complexes were recrystallized from MeCN-MeOH mixture (yield:
70 %).
˚
Table 4 Selected bond distances /A and angles /° for [Ni(nmedtc)
(1,3-dppp)]ClO4·H2O
Ni1 Ϫ S2
Ni1 Ϫ S3
Ni1 Ϫ P4
Ni1 Ϫ P5
S2 Ϫ C6
S3 Ϫ C6
N7 Ϫ C8
C8 Ϫ C9
P4 Ϫ C14
P4 Ϫ C17
2.202(2)
2.197(3)
2.185(2)
2.170(2)
1.721(1)
1.745(1)
1.468(2)
1.487(3)
1.830(5)
1.805(5)
P5 Ϫ C16
P5 Ϫ C29
P5 Ϫ C35
C14 Ϫ C15
C15 Ϫ C16
C17 Ϫ C22
C6 Ϫ N7
N7 Ϫ C11
C9 Ϫ O10
P4 Ϫ C23
1.835(7)
1.824(5)
1.808(4)
1.510(1)
1.542(5)
1.380(4)
1.286(1)
1.447(2)
1.519(2)
1.829(6)
X-ray crystallography
P5 Ϫ Ni1 Ϫ P4
P5Ϫ Ni1 Ϫ S2
P5 Ϫ Ni1 Ϫ S3
P4 Ϫ Ni1 Ϫ S3
P4 Ϫ Ni1 Ϫ S2
S2 Ϫ Ni1 Ϫ S3
S2 Ϫ C6 Ϫ S3
Ni1 Ϫ S2 Ϫ C6
Ni1 Ϫ S3 Ϫ C6
Ni1 Ϫ P4 Ϫ C14
Nil Ϫ P4 Ϫ C23
C14 Ϫ P4 Ϫ C17
96.5(2)
92.1(3)
171.1(2)
92.0(2)
170.6(3)
79.3(3)
108.2(1)
86.1(4)
85.7(2)
117.2(3)
111.6(4)
104.3(2)
Ni1 Ϫ P5 Ϫ C16
Ni1 Ϫ P5 Ϫ C35
C16 Ϫ P5 - C29
C16 Ϫ P5 Ϫ C35
S2 Ϫ C6 Ϫ N7
S3 Ϫ C6 Ϫ N7
C6 Ϫ N7 Ϫ C8
C6 Ϫ N7 Ϫ C11
N7 Ϫ C8 Ϫ C9
Ni1 Ϫ P4 Ϫ C17
C14 Ϫ P4 Ϫ C23
Ni1 Ϫ P5 Ϫ C29
116.8(2)
111.9(3)
104.6(3)
104.6(3)
125.5(1)
126.3(2)
120.7(2)
121.1(2)
104.2(3)
112.2(4)
105.1(4)
112.9(5)
Details of the crystal data, data collection and refinement para-
meters for thecomplex are summarized in Table 3. The intensity
data were collected on a Siemens AED diffractometer by using
˚
Mo-Kα radiation (λ ϭ 0.71069 A). Structure was solved by SIR
92 [23] program and refined by SHELX 93 [24]. The absorption
correction was performed with the method of Walker and Stuart
[25] with a program written by Gluzinski [26]. All the nonhydrogen
atoms were refined anisotropically and all the hydrogen atoms were
refined isotropically. Selected bond distances and angles are pre-
sented in Table 4.
Z. Anorg. Allg. Chem. 2006, 461Ϫ464
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
zaac.wiley-vch.de
463

A. Manohar, K. Ramalingam, R. Thiruneelakandan, G. Bocelli, L. Righi
[14] A. Manohar, K. Ramalingam, G. Bocelli, L. Righi, Inorg.
Chim. Acta 2001, 314, 172.
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Z. Anorg. Allg. Chem. 2006, 461Ϫ464