Titanocene complexes of the N-methyl and N-phenyl-1,3-thiazoline-2-thione-4,5-dithiolates and 4,5-diselenolate ligands

Article abstract of DOI:10.1016/j.jorganchem.2008.05.021

Cp₂Ti(dithiolene) and Cp₂Ti(diselenolene) complexes containing the N-methyl-1,3-thiazoline-2-thione-4,5-dithiolate ligand (Me-thiazdt), the N-phenyl-1,3-thiazoline-2-thione-4,5-dithiolate ligand (Ph-thiazdt) and the N-methyl-1,3-thia

Full text of DOI:10.1016/j.jorganchem.2008.05.021

Journal of Organometallic Chemistry 693 (2008) 2755–2760
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Journal of Organometallic Chemistry
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Titanocene complexes of the N-methyl and N-phenyl-1,3-thiazoline-2-thione-4,5-
dithiolates and 4,5-diselenolate ligands
*
Samar Eid, Thierry Roisnel, Dominique Lorcy
Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Campus de Beaulieu, Bât 10A, 35042 Rennes cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 April 2008
Received in revised form 14 May 2008
Accepted 14 May 2008
Available online 22 May 2008
Cp2Ti(dithiolene) and Cp2Ti(diselenolene) complexes containing the N-methyl-1,3-thiazoline-2-thione-
4,5-dithiolate ligand (Me-thiazdt), the N-phenyl-1,3-thiazoline-2-thione-4,5-dithiolate ligand (Ph-thia-
zdt) and the N-methyl-1,3-thiazoline-2-thione-4,5-diselenolate ligand (Me-thiazds) have been synthe-
sized. Three approaches have been developed in order to generate the dithiolene or the diselenolene
ligands which were reacted with Cp2TiCl2 to form the corresponding heteroleptic complexes. Their X-
ray crystal structures, UV–Vis absorption spectra as well as their redox properties, determined by cyclic
voltammetry have been investigated and discussed. Variable-temperature 1H NMR experiments have
been performed in order to determine the activation energies of the chelate ring inversion.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords:
Titanocene
Dithiolene
Diselenolene
Thiazole
Crystal structure
1. Introduction
sulfur analogues Cp2Ti(dmit) and Cp2Ti(dsit) and to determine
the influence of the thiazole skeleton. It is interesting to note that
Mixed cyclopentadienyl/dithiolene complexes such as
Cp2M(dithiolène) [1] (M = Ti [2,3] Zr and Hf [3], V [4], Nb [5], Mo
[6] and W [6,7]), exhibit different geometries according to the
metal, the nature and the redox state of the ligand. Among these
complexes, the metal which focused the most the attention is Tita-
nium. Indeed, these diamagnetic complexes, Cp2Ti(dithiolene) first
described by Köpf and Schmidt more than 40 years ago [8] are usu-
ally obtained in good yields, are air stable and can be considered as
inorganic protected forms of the air-sensitive 1,2-dithiolate.
Rauchfuss et al. reported later a series of Cp2Ti(diselenolene) ana-
logues exhibiting similar properties [9]. All these heteroleptic com-
plexes exhibit an out-of-plane deformation of the metallacycle
with a folding around the SS axis of about 43° < h < 50°, as repre-
sented in Chart 1 [10]. This folding has been attributed to the sta-
bilizing interaction of metal and sulfur orbitals and the lowering of
the total energy of the system [10,11].
only one other example of a metal dithiolene complex involving
R-thiazdt has been reported to date, as its CpCo complex, that is
CpCo(R-thiazdt) (R = Me, Ph, CH2Ph) obtained by a four step
lengthy synthesis [13].
2. Results and discussion
2.1. Synthesis of Cp2Ti(R-thiazdt) and Cp2Ti(R-thiazds)
In the literature, the main route employed for the synthesis of
Cp2Ti(dmit) is the use of the 1,3-dithiole-2-thione-4,5-dithiolate
(dmit) either under the tetraethylammonium salt of its zinc com-
plex [14] or the sodium or potassium salt [2,3] generated from
4,5-bis(benzoylthio)-1,3-dithiole-2-thione. The dithiolene reacts
further with the organometallic precursor, Cp2TiCl2 through the
substitution of the chlorines by thiolates. The selenium analogue,
Cp2Ti(dsit), synthesized first by Olk et al. was also prepared
according to a similar strategy [15,16]. The cesium salt of the
1,3-dithiole-2-thione-4,5-diselenolate (dsit), generated from the
4,5-bis(benzoylseleno)-1,3-dithiole-2-thione, was reacted with
Cp2TiCl2 to afford Cp2Ti(dsit). Here, three different chemical ap-
proaches have been investigated for the synthesis of the target
molecules. First, Cp2Ti(R-thiazdt) complexes were synthesized
starting from the thiazole-2-thione derivatives 1a [17] (R = Me)
and 1b [18] (R = Ph) as shown in Scheme 1. This strategy consists
in generating the dilithiated species from the thiazole-2-thione
derivatives in the presence of LDA, followed by the addition of
In continuation of our studies on metal complexes involving N-
methyl-1,3-thiazoline-2-thione-4,5-dithiolate, [M(Me-thiazdt)2]nꢀ
,
or N-methyl-1,3-thiazoline-2-thione-4,5-diselenolate, [M(Me-thia-
zds)2]nꢀ (Zn, Ni and Pd) [12], we have investigated heteroleptic
metal complexes containing both cyclopentadienyl and dithiolene
or diselenolene moieties substituted with a thiazole backbone such
as Cp2M(R-thiazdt) or Cp2M(R-thiazds). Our goal was to compare
the properties of these hitherto unknown derivatives with their
* Corresponding author. Tel.: +33 2 23 23 62 73; fax: +33 2 23 23 67 38.
E-mail address: dominique.lorcy@univ-rennes1.fr (D. Lorcy).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.05.021

2756
S. Eid et al. / Journal of Organometallic Chemistry 693 (2008) 2755–2760
Me
N
S
N
X
X
X
X
X
X
S
N
Cp2TiCl2
Me
-X
-X
S
-X
-X
Zn
S (NEt4)2
Ti
S
θ
S
S
N
THF, Δ 3h
S
S
S
Me
[NEt4]2[Zn(thiazdt)2] X = S
[NEt4]2[Zn(thiazds)2] X = Se
Me
S
2a X = S
43° < θ < 50 °
3a X = Se
X = S dmit
X = Se dsit
X = S Me-thiazdt
X = Se Me-thiazds
X = S Cp2Ti(dithiolene)
X = Se Cp2Ti(diselenolene)
Scheme 3.
Chart 1.
2), the N-methyl-bis(cyanoethylthio)-1,3-thiazoline-2-thione
and N-methyl-bis(cyanoethylseleno)-1,3-thiazoline-2-thione
4
5
where the two thiolate and selenolate functions are protected by
cyanoethyl groups. These derivatives have been prepared earlier
from [NEt4]2[Zn(Me-thiazdt)2] and [NEt4]2[Zn(Me-thiazds)2] [12].
Herein, we present another direct route from the thiazole-2-thione
1a as described in Scheme 2. After the treatment of 1a at low tem-
perature with LDA and the chalcogen sulfur or selenium, 3-bromo-
propionitrile was added to the medium. Work up of the reaction
leads to compounds 4 and 5, easily isolated after column chroma-
tography in 60% and 43% yield, respectively. Deprotection of the
thiolate and selenolate functions was realized in basic medium
using cesium hydroxide, addition of Cp2TiCl2 allowed us to isolate
the dithiolene complexes 2a and 3a in an improved 40% yield.
The last approach towards target molecules consists in the
heating to reflux of the inorganic dithiolate or diselenolate hidden
form, the tetraethylammonium salt of the dithiolate zinc complex
[19], [NEt4]2[Zn(thiazdt)2] or diselenolate zinc complex
[NEt4]2[Zn(thiazds)2] [12] in the presence of 2 equiv of Cp2TiCl2
during 3 h (Scheme 3). Using this strategy, we were able to isolate
2a in 74% yield and 3a in 67% yield. The advantages of this ap-
proach lies in the fact that the corresponding complexes are easier
to purify by a quick filtration on silica gel column and are obtained
in higher yields.
LiS
LiS
S
N
S
N
S
S
S
N
1) LDA
2) S8
Cp2TiCl2
S
S
Ti
S
R
R
R
Cp2Ti(R-thiazdt)
1a R = Me
1b R = Ph
2a R = Me
2b R = Ph
Se
S
N
1) LDA, 2) Se
3) Cp2TiCl2
Ti
S
Se
Me
Cp2Ti(R-thiazds)
3a
Scheme 1.
sulfur. While the formation of the dithiolate from 1a was already
described by us during our investigation on the formation of
homoleptic complexes [12], we investigated also the possibility
of forming the dithiolate species from other N-substituted thiazole
cores such as 1b. The generated dithiolate reacts in situ with the
organometallic complex, Cp2TiCl2. The corresponding Cp2Ti(R-thia-
zdt), 2a (R = Me) and 2b (R = Ph), were isolated as green crystals in
10% and 30% yields, respectively, after purification on column
chromatography and recrystallization in chloroform. A similar
approach was used to prepare the corresponding diselenolene
analogue, Cp2Ti(R-thiazds). Actually, using this strategy, we were
able to isolate the Cp2Ti(Me-thiazds) 3a as blue crystals in only
10% yield.
2.2. X-ray structure analysis
Crystals of the heteroleptic complexes 2a, 2b and 3a were iso-
lated after recrystallization in chloroform. Cp2Ti(Me-thiazdt) 2a
and Cp2Ti(Me-thiazds) 3a crystallize in the orthorhombic system,
space group Pna21 and are isostructural. Cp2Ti(Ph-thiazdt) 2b crys-
tallizes in the monoclinic system, space group P21/c. X-ray molec-
ular structures for the three complexes are given in Fig. 1.
Considering the low yield obtained for 2a and 3a by this direct
route, we considered a second strategy which consists in starting
from an organic dithiolate or diselenolate hidden form (Scheme
All these heteroleptic complexes exhibit the same structural
trends: a fully planar thiazole core and a non planar metallacycle
X(CH2)2CN
S
N
X
X
S
N
S
N
CsOH, H20
Cp2TiCl2
1) LDA, 2) X
3) Br(CH2)2CN
S
Ti
S
S
X(CH2)2CN
Me
Me
Me
X = S, Se
4 X = S
1a
2a X = S
5 X = Se
3a X = Se
Scheme 2.
Fig. 1. Molecular structures of Cp2Ti(R-thiazdt) 2a (left), 2b (middle) and Cp2Ti(Me-thiazds) 3a (right).

S. Eid et al. / Journal of Organometallic Chemistry 693 (2008) 2755–2760
2757
Table 1
Significant bond lengths [Å] and angles [°], with X = S or Se
Compound
Ti–X (Å)
X–C (Å)
C@C (Å)
X–Ti–X (°)
h (°)a
Cp2Ti(Me-thiazdt) 2a
2.4336(10)
2.4516(10)
1.714(4)
1.722(3)
1.386(5)
85.30(4)
48.34(13)
50.41(7)
47.45(39)
48.19(21)
49.84(8)
Cp2Ti(Ph-thiazdt) 2b
Cp2Ti(dmit) [2]
2.4195(6)
2.4486(6)
1.7199(18)
1.7274(18)
1.377(3)
1.357(15)
1.357(8)
1.372(7)
86.005(18)
84.40(2)
85.21(4)
84.62(3)
2.434(3)
2.430(41)
1.733(12)
1.718(8)
Cp2Ti(Me-thiazds) 3a
Cp2Ti(dsit) [16]
2.5680(12)
2.5799(12)
1.879(6)
1.879(6)
2.5697(17) 2.5743(17)
1.884(6) 1.878(6)
a
See Chart 1 for the definition of h.
folded along the Sꢁ ꢁ ꢁS axis for the Cp2Ti(R-thiazdt) or the Seꢁ ꢁ ꢁSe
axis for Cp2Ti(Me-thiazds). Selected bond lengths and folding an-
gles are listed in Table 1 together with their dithiole analogues,
Cp2Ti(dmit) and Cp2Ti(dsit) for comparison. The bond lengths,
Tiꢁ ꢁ ꢁX and Xꢁ ꢁ ꢁC (X = S, Se), in the metallacycles of 2a–b and 3a
are very close to the ones observed in the corresponding Cp2Ti-
(dmit) and Cp2Ti(dsit) complexes. The ligand bite angles, S–Ti–S
(85.30(4)° for 2a and 86.005(18)° for 2b) or Se–Ti–Se (85.21(4)°
for 3a) are in the same range as the ones observed for the dithiole
analogues [2,16]. The phenyl ring mean plane in 2b forms an angle
with the thiazole core mean plane of 61.3(2)°. The folding angles
(h) within the metallacycle of complexes 2a–b and 3a are in the
range of the folding angles observed for Cp2Ti(dmit) and Cp2Ti-
(dsit) indicating that the nature of the heterocycle, thiazole or
dithiole has no significant influence on the geometry of the metal-
lacycle TiS2C2 (or TiSe2C2) of these heteroleptic complexes.
Table 3
Variable-temperature 1H NMR data
¼
DG )
(kJ molꢀ1
Complex h (°)
Solvent TC (°C)
D
m
(Hz)
Cp2Ti(Me-thiazdt) 2a 48.34(13) CD3CN
+53
+50
35
302
236
84
290
100
60.6
60.6
60.0
58.5
60.0
Cp2Ti(Ph-thiazdt) 2b
50.41(7)
CD3CN
Cp2Ti(dmit) [2]
47.45(39) CDCl3
Cp2Ti(Me-thiazds) 3a 48.19(21) CD3CN
Cp2Ti(dsit) [16] 49.84(8) CDCl3
42
+28
2.3. Electrochemical properties
The redox behaviour of Cp2Ti(R-thiazdt) 2a–b and Cp2Ti(R-thia-
zds) 3a has been studied by cyclic voltammetry in dichlorometh-
ane solution with 0.1 M nBu4NPF6 as supporting electrolyte. The
data are collected in Table 3 and are given in V vs. SCE together
with the redox potentials of the sulfur Cp2Ti(dmit) and selenium
Cp2Ti(dsit) analogues which were re-examined in the same exper-
imental conditions for comparison. All these complexes are neutral
and stable upon air atmosphere and exhibit very similar cyclic vol-
tammograms as the one shown in Fig. 2. On the anodic scan, an
irreversible oxidation wave appears while on the cathodic scan, a
reversible reduction wave is observed. The oxidation wave is
attributed to the oxidation of the dithiolene or diselenolene ligand
and the irreversibility of the process is a consequence of the deco-
ordination of the oxidized ligand from the complex. Indeed, theo-
Fig. 2. Cyclic voltammogram of complex Cp2Ti(Ph-thiazdt) 2b, scanning rate
100 mV/s.
retical analysis performed by Dahl et al. have shown that
removal of electron from the HOMO of such complexes, which is
strongly metal ligand bonding, severely weakens the metal ligand
interaction [20]. The reversible reduction process observed corre-
sponds to the reduction of the metal Ti(IV)/Ti(III)
.
We also observe that the oxidation of the N-phenyl substituted
thiazole derivative 2b occurs at a more positive potential (+40 mV)
than that of the N-methyl one 2a. This indicates a small electron
withdrawing influence of the phenyl ring on the heterocycle. Con-
trariwise, the nature of the coordinating chalcogen atom (S vs. Se)
does not modify the oxidation potential of the complex. It can also
be noticed on both series, dithiolene and diselenolene, that the oxi-
dation of the thiazole derivatives is observed at a lower potential
than the oxidation of the dithiole derivative indicating that the
most electron rich ligand is the thiazdt over dmit and thiazds over
dsit. This is also consistent with the reduction potentials observed
for the Ti(IV)/Ti(III) process. Indeed, the electron releasing effect of
the thiazole core compared with the dithiole one induces a nega-
tive shift of the redox potentials indicating that the metal is then
more difficult to reduce in Cp2Ti(thiazdt) 2a–b (ꢀ0.92 V vs. SCE)
than in Cp2Ti(dmit) (ꢀ0.82 V vs. SCE). Similar observations can
be made in the diselenolene series.
Table 2
Redox potentialsa in V vs. SCE and UV–Vis absorption band and extinction coefficient
of Cp2Ti(R-thiazdt) 2a–b, Cp2Ti(Me-thiazds) 3a, Cp2Ti(dmit) and Cp2Ti(dsit)
Complex
Ea (TiIV/TiIII
ꢀ0.92
)
Epa
kmax (nm) (e
[Mꢀ1 cmꢀ1])
Cp2Ti(Me-thiazdt) 2a
+0.78
653 (7600), 493 (5010),
347 (21420)
Cp2Ti(Ph-thiazdt) 2b
Cp2Ti(dmit)
ꢀ0.92
ꢀ0.82
ꢀ0.86
ꢀ0.79
+0.82
+0.96
+0.78
+0.96
643 (8620), 489 (4550),
346 (15820)
639 (5300), 490 (3400),
425 (9100), 290 (21700) [3]
702 (6940), 505 (4180),
353 (21770)
Cp2Ti(Me-thiazds) 3a
Cp2Ti(dsit)
a
determined in CH2Cl2 by cyclic voltammetry using nBu4PF6 as supporting
electrolyte, Pt working electrode, scan rate 100 mV/s.

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S. Eid et al. / Journal of Organometallic Chemistry 693 (2008) 2755–2760
2.4. 1H NMR experiments
As demonstrated from the X-ray structure analysis, the metalla-
cycles of 2a–b and 3a are non planar in the solid state with a tor-
sion angle between 48° and 50°. Room temperature 1H NMR
investigation in CDCl3 or in CD3CN shows that the two cyclopenta-
dienyl groups are indeed not equivalent due to different surround-
ings and two singlets are observed. Variable temperature 1H NMR
experiments performed in CD3CN provided activation energies for
the ring inversion process. Indeed, upon raising the temperature,
coalescence of the two signals appears on the spectra at Tc (coales-
cence temperature), as shown in Fig. 3, due to a rapid inversion
process as suggested by Köpf on other Cp2Ti(dithiolene) [21].
Determination of Tc and the use of Eyring equation [22] allowed
¼
¼
us to determine the activation energy
DG . The data (h, Tc, DG )
for the complexes 2a–b and 3a are collected in Table 3 together
with those of Cp2Ti(dmit) and Cp2Ti(dsit) for comparison. It can
be noticed that the nature of the heterocycle ring, thiazole or
dithiole does not influence the value of the activation energy for
the inversion process, as also the nature of the chalcogen atom
coordinated to the metal.
Fig. 4. UV–Vis–NIR absorption spectrum of 2b Cp2Ti(Ph-thiazdt) (CH2Cl2, C = 10ꢀ4
M).
tution of the thiazole ring for a dithiole ring do not modify signif-
icantly the absorption spectra. A bathochromic shift of about
50 nm can be noticed for Cp2Ti(Me-thiazds) when compared with
Cp2Ti(Me-thiazdt).
2.5. UV–Vis–NIR spectra
Absorption spectra of the titanocene complexes 2a–b and 3a are
measured in dichloromethane. The absorption maxima and extinc-
tion coefficients are collected in Table 2. The three complexes ex-
hibit similar absorption spectra with absorption bands in the
UV–Vis region as the one shown for 2b, Cp2Ti(Ph-thiazdt), in Fig. 4.
These bands are assigned to ligand metal transitions (LMCT). It
can be observed that, among the different dithiolene ligands, either
the substitution of a methyl group for a phenyl group or the substi-
3. Conclusion
In summary, we have synthesized a novel family of heteroleptic
complexes involving bis(cyclopentadienyl)titanocene dithiolene or
diselenolene on a thiazole backbone and have shown that it was
possible to insert different substituents on the nitrogen, N-Me
and N-Phe. We also investigated their structural and redox proper-
ties and compared them with their dithiole analogues Cp2Ti(dmit)
and Cp2Ti(dsit). The synthesized complexes exhibit a good stability
and structural flexibility was evidenced through variable tempera-
ture 1H NMR experiments. The nature of the heterocyclic backbone
does not influence significantly the spectral and structural proper-
ties, especially the folding angles (h) and the activation energy for
the inversion process, even if the thiazole core is a better electron
releasing group than the dithiole one as evidenced by the redox
properties [10]. One attractive peculiarity of these complexes with
a thiazole core is the presence of an anchoring point for other func-
tionalities through the nitrogen atom. We have shown here that
the synthetic strategy developed earlier for the N-Me derivatives
could be successfully extended to the N-Ph one. Further work will
be devoted to the preparation of other paramagnetic heteroleptic
complexes as well as modification of the phenyl ring.
4. Experimental
4.1. General
All reagents were commercially available and used without fur-
ther purification. CsOH ꢁ H2O and selenium powder (200 mesh)
were purchased from Acros organics. [NEt4]2[Zn(Me-thiazdt)2]
and [NEt4]2[Zn(Me-thiazds)2] were synthesized according to liter-
ature procedure [12]. Tetrahydrofuran was distilled from sodium-
benzophenone. CH2Cl2 was distilled from P2O5. Chromatography
was performed using silica gel Merck 60 (70–260 mesh melting
points were measured using a Kofler hot-stage apparatus. 1H
NMR and 13C NMR spectra were recorded on Bruker AC 300P spec-
trometer. Chemical shifts are reported in ppm referenced to TMS
for1H NMR and 13C NMR. For the variable temperature 1H NMR
studies, data were exploiting by using the Eyring equation [22]
¼
DG
= ꢀ RTcln(kch/kBTc) where kc is equal to 2ꢀ1/2p
Dm and Dm is
Fig. 3. Variable temperature 1H NMR spectra of Cp2Ti(Ph-thiazdt) 2b in CD3CN.
the frequency difference between the two cyclopentadienyl shifts

S. Eid et al. / Journal of Organometallic Chemistry 693 (2008) 2755–2760
2759
Table 4
in the slow exchange limit (T ꢂ Tc). UV–Vis–NIR spectra were re-
Crystal data and structure refinement parameters for 2a, 2b and 3a
corded on a Cary 5 spectrophotometer in CH2Cl2. Mass spectra
were recorded with Varian MAT 311 instrument and a ZABSpec
TOF instrument by the Centre Régional de Mesures Physiques de
l’Ouest, Rennes. Elemental analyses were performed at the Centre
Régional de Mesures Physiques de l’Ouest, Rennes). Cyclic voltam-
metry was carried out on a 10ꢀ3 M solution of metal complex
derivative in CH2Cl2 containing 0.1 M n-Bu4NPF6 as supporting
electrolyte. Voltammograms were recorded at 0.1 V sꢀ1 on a plati-
num disk electrode (1 mm2). Potentials were measured vs. satu-
rated calomel electrode (SCE).
Compound
2a
3a
2b
Formula
C14H13NS4Ti
C14H13NS2Se2Ti
465.19
Orthorhombic
Pna21
9.8377(7)
10.1415(8)
15.6379(12)
90
90
90
1560.2(2)
100(2)
4
C19H15NS4Ti
433.46
Monoclinic
P21/n
8.2138(5)
20.1931(13)
11.4373(7)
90
107.748(3)
90
1806.73(19)
100(2)
4
1.594
0.938
FW (g molꢀ1
)
371.39
Orthorhombic
Pna21
9.7661(3)
10.1436(7)
15.6116(11)
90
Crystal system
Space group
a (Å)
b (Å)
c (Å)
a
(°)
b (°)
90
90
c
(°)
V (Å3)
1546.54(16)
293(2)
4
1.595
1.080
25089
3297 (0.0284)
2931 (I > 2
0.0306, 0.0831
0.0427, 0.0997
1.303
4.2. Synthesis and characterization
T (K)
Z
Dcalc (g cmꢀ3
)
1.980
5.469
7570
3208 (0.0532)
4.2.1. General procedure for the synthesis of Cp2Ti(R-thiazdt) 2a–b
and Cp2Ti(Me-thiazds) 3a
l
(mmꢀ1
)
Total reflection
24435
3974 (0.0432)
3448 (I > 2r(I))
0.0302, 0.0732
0.0373, 0.0767
1.036
Method a (Scheme 1): To a solution of thiazoline-2-thione
(3.8 mmol, 0.5 g for 1a or 0.74 g for 1b) in dry THF (40 mL) was
added a solution of LDA freshly prepared from BuLi (5.7 mmol,
3.6 mL, 1.6 M in hexane) and diisopropylamine (5.7 mmol, 0.58 g)
in 15 mL of dry THF. After the mixture has been stirred for
30 min at ꢀ10 °C, S8 (5.7 mmol, 0.18 g) for 2a–b or Se (5.7 mmol,
0.45 g) for 3a was added and the solution was stirred for an addi-
tional 30 min. To the medium a solution of LDA (7.6 mmol, 4.76 mL
of nBuLi in hexane added to 7.6 mmol, 0.77 g of diisopropylamine
in 20 mL of dry THF) was added. The reaction mixture was stirred
at ꢀ10 °C for 3 h, then sulfur S8 (0.24 g, 7.6 mmol) for 2a–b or sele-
nium (7.6 mmol, 0.6 g) for 3a was added. After 30 min, Cp2TiCl2
(3.8 mmol, 0.95 g) was added to the medium and the reaction mix-
ture was stirred for 15 h. The solvent was evaporated in vacuo and
the residue was extracted with CH2Cl2. The concentrated solution
was subjected to flash chromatography on silica gel using CH2Cl2
as the eluant. The complex was recrystallized from CHCl3, filtration
afforded 2a in 10 % yield, 2b in 30% yield and 3a in 10% yield.
Method b (Scheme 2): The 4,5-bis (20-cyanoethylthio)-1,3-thia-
zol-2-thione 4 and 4,5-bis (20-cyanoethylseleno)-1,3-thiazol-2-thi-
one 5 are prepared according to the method a, given above, by
using 3-bromopropionitrile (1 g, 7.6 mmol) instead of Cp2TiCl2.
After the work up of the reaction mixture, the thiazoline thione 4
and 5 were obtained in 60% and 43% yield, respectively (data are
given in Ref. [12]). To a stirred solution of 1,3-thiazoline-2-thione
(500 mg, 1.65 mmol for 4), or (650 mg, 1.65 mmol for 5) in dry
THF (20 mL), under argon, was added CsOH, H2O (610 mg,
3.65 mmol) dissolved in MeOH (6 mL). The mixture was stirred
30 min at room temperature and Cp2TiCl2 (410 mg, 1.65 mmol)
was added. After stirring for 1 h, during which time the solution
became dark blue–green, the solvent was concentrated in vacuo.
The residue was chromatographied on silica gel column using
CH2Cl2 as eluent. The complexes are obtained after recrystalliza-
tion in CHCl3 in 40% yield.
Unique reflection (Rint
Unique reflection
R1, wR2
R1, wR2 (all data)
Goodness-of-fit (GoF)
)
r
(I))
2948 (I > 2
r(I))
0.0394, 0.0830
0.0436, 0.0841
1.091
Compound 2b Cp2Ti(Ph-thiazdt), green crystals, m.p. = 270 °C,
Rf = 0.68 (CH2Cl2); 1H NMR (CDCl3, 300 MHz) d = 5.60 (s, 5H, Cp),
6.09 (s, 5H, Cp), 7.38–7.63 (m, 5H, Ph); 13C NMR (CDCl3, 75 MHz)
d = 107.86 (Cp), 112.34 (Cp), 128.13 (@C, Ar), 128.69 (2@C, Ar),
129.73 (2@C, Ar), 131.59 (@C), 138.52 (NC, Ar), 144.17 (@C),
191.64 (C@S); Anal. Calc. for C19H15NS4Ti: C, 52.65; H, 3.49; N,
3.23; S, 29.59. Found: C, 52.55; H, 3.61; N, 3.29; S, 29.82%. UV–
Vis–NIR (CH2Cl2): kmax = 643 nm
(e
= 8620 L molꢀ1 cmꢀ1); 489
(e
= 4550 L molꢀ1 cmꢀ1); 346 ( = 15820 L molꢀ1 cmꢀ1).
e
Compound 3a Cp2Ti(Me-thiazds), blue crystals, m.p. = 250 °C,
Rf = 0.67 (CH2Cl2). 1H NMR (CDCl3, 300 MHz) d = 3.90 (s, 3H, CH3),
5.65 (s, 5H, Cp), 6.23 (s, 5H, Cp); 13C NMR (CDCl3, 75 MHz)
d = 38.41 (CH3), 108.95 (Cp), 111.95 (Cp), 125.79 (@C), 143.33
(@C), 191.40 (C@S); HRMS calc. for C14H13NS248Ti80Se2: 466.8299.
Found: 466.8310; HRMS Calc. for [M+H]+ C14H14NS248Ti80Se2:
467.8377. Found: 467.8361; UV–Vis–NIR (CH2Cl2): k = 702 nm
(
(
e
e
= 6940 L molꢀ1 cmꢀ1);
= 21770 L molꢀ1 cmꢀ1).
505
(
e
= 4180 L molꢀ1 cmꢀ1);
353
4.3. Crystallography
Single-crystal diffraction data were collected on a Nonius
KappaCCD diffractometer from the University of Angers for com-
pound 2a and on APEX II Bruker AXS diffractometer for compounds
2b and 3a (Centre de Diffractométrie X, Université de Rennes,
France). Details of the crystallographic are given in Table 4.
Acknowledgments
Method c (Scheme 3): To a stirred solution of [NEt4]2[Zn(thia-
zdt)2] (130 mg, 0.18 mmol) or [NEt4]2[Zn(thiazds)2] (160 mg,
0.18 mmol) in dry THF (20 mL) was added Cp2TiCl2 (90 mg,
0.36 mmol). The reaction mixture was stirred for 3 h to reflux
under argon. The solution turn dark blue green and becomes
homogeneous. The medium is then filtered on silica gel column
and eluted with CH2Cl2 to afford 2a (100 mg, 74 % yield) and 3a
(90 mg, 67% yield).
We thank Sourisak Sinbandhit from the Centre Régional de
Mesures Physiques de l’Ouest, Rennes, for VT 1H NMR data collec-
tion. The authors are indebted to Marc Fourmigué for X-ray data
collections at the University of Angers.
Appendix A. Supplementary material
Compound 2a Cp2Ti(Me-thiazdt), green crystals, m.p. = 268 °C;
Rf = 0.68 (CH2Cl2); 1H NMR (CDCl3, 300 MHz) d = 3.77 (s, 3H,
CH3), 5.51 (s, 5H, Cp), 6.13 (s, 5H, Cp); 13C NMR (CDCl3, 75 MHz)
d = 36.14 (CH3), 107.94 (Cp), 112.34 (Cp), 131.23 (@C), 144.56
(@C), 190.36 (C@S); HRMS calc. for C14H14NS448Ti: 371.9489.
CCDC 685463, 685464 and 685465 contain the supplementary
crystallographic data for 2a Cp2Ti(Me-thiazdt), 2b Cp2Ti(Ph-thia-
zdt) and 3a Cp2Ti(Me-thiazds). 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 associ-
ated with this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2008.05.021.
Found: 371.9490; UV–Vis–NIR (CH2Cl2): k = 653 nm
(
e
= 7600
L molꢀ1 cmꢀ1); 493
molꢀ1 cmꢀ1).
(e (e = 21420 L
= 5010 L molꢀ1 cmꢀ1); 347

2760
S. Eid et al. / Journal of Organometallic Chemistry 693 (2008) 2755–2760
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