Redox-active dithiafulvenyldiphenylphosphine as a mono- or bidentate ligand: Intramolecular coupling reaction in the coordination sphere of a metal carbonyl fragment

Article abstract of DOI:10.1021/ic0501465

The coordinating ability of dithiafulvenyldiphenylphosphine (P-DTF) has been investigated with cis-W(CO)₄(piperidine)₂. As shown by the metal carbonyl complexes obtained, this redox-active vinylphosphine can act as a monodentate (P) and as a bidentate (P,S) ligand. Oxidation of cis-M(CO)₄(P-DTF)₂, M = Mo and W, leads to the carbon-carbon bond formation between the two coordinated dithiafulvenyldiphenylphosphines. This chemical coupling of the dithiafulvenyl cores in the coordination sphere of M(CO)₄ (M = Mo, W) fragment has been studied in the presence of various oxidizing agents. The use of (BrC ₆H₄)₃NSbCl₆ or AgBF₄ induces the formation of a five-membered metallacycle with a vinylogous TTF backbone while DDQ leads to a six-membered metallacycle. The syntheses, crystal structures, and electrochemical properties of the complexes obtained are described.

Full text of DOI:10.1021/ic0501465

Inorg. Chem. 2005, 44, 3347−3355
Redox-Active Dithiafulvenyldiphenylphosphine as a Mono- or Bidentate
Ligand: Intramolecular Coupling Reaction in the Coordination Sphere of
a Metal Carbonyl Fragment
Michel Guerro,† Thierry Roisnel,‡ Pascal Pellon,† and Dominique Lorcy*,†
Groupe He´te´rochimie et Mate´riaux Electroactifs, SESO UMR 6510 CNRS-UniVersite´ de Rennes 1,
Institut de Chimie de Rennes, Campus de Beaulieu, Baˆt 10A, 35042 Rennes Cedex, France,
and Laboratoire de Chimie du Solide et Inorganique Mole´culaire, UMR 6511
CNRS-UniVersite´ de Rennes 1, Institut de Chimie de Rennes, Campus de Beaulieu,
Baˆt 10B, 35042 Rennes Cedex, France
Received January 28, 2005
The coordinating ability of dithiafulvenyldiphenylphosphine (P-DTF) has been investigated with cis-W(CO)4(piperi-
dine)2. As shown by the metal carbonyl complexes obtained, this redox-active vinylphosphine can act as a
monodentate (P) and as a bidentate (P,S) ligand. Oxidation of cis-M(CO)4(P-DTF)2, M
carbon carbon bond formation between the two coordinated dithiafulvenyldiphenylphosphines. This chemical coupling
of the dithiafulvenyl cores in the coordination sphere of M(CO)4 (M Mo, W) fragment has been studied in the
) Mo and W, leads to the
−
)
presence of various oxidizing agents. The use of (BrC6H4)3NSbCl6 or AgBF4 induces the formation of a five-
membered metallacycle with a vinylogous TTF backbone while DDQ leads to a six-membered metallacycle. The
syntheses, crystal structures, and electrochemical properties of the complexes obtained are described.
Introduction
organic and inorganic properties in one building block.
Various coordination functions have been used to build these
hybrid molecules, essentially thiolates,1 phosphines,2-5 and
pyridines.6-8 Within this frame, we recently presented a
bidentate diphosphine complex with a vinylogous tetrathia-
fulvalene backbone (cis-Mo(CO)4(P,P-TTFV) which was
prepared thanks to an unprecedented metal template effect
of molybdenum carbonyl Mo(CO)4 fragment.9 Indeed, the
two dithiafulvene moieties in Mo(CO)4(P-DTF)2, cis coor-
dinated to the metal via the phosphine, form upon oxidation
of the vinylogous tetrathiafulvalene core (TTFV) while no
coupling reaction was observed for the free uncoordinated
vinylphosphine (P-DTF).
The chemistry of hybrid molecules involving redox-active
organic cores such as tetrathiafulvalene (TTF) linked to a
metal through a coordination function is currently a topic of
great interest.1-8 The motive power of this research is to
create new materials by association and/or interaction of the
* Author to whom correspondence should be addressed. E-mail:
dominique.lorcy@univ-rennes1.fr. Fax: (33) 2 23 23 67 38.
† SESO UMR 6510 CNRS-Universite´ de Rennes 1.
‡ UMR 6511 CNRS-Universite´ de Rennes 1.
(1) Kobayashi, A.; Fujiwara, E.; Kobayashi, H. Chem. ReV. 2004, 104,
5243 and references therein.
(2) (a) Fourmigue´, M.; Batail, P. Bull. Soc. Chim. Fr. 1992, 129, 29. (b)
Fourmigue´, M.; Uzelmeier, C. E.; Boubekeur, K.; Bartley, S. L.;
Dunbar, K. R. J. Organomet. Chem. 1997, 529, 343. (c) Uzelmeier,
C. E.; Bartley, S. L.; Fourmigue´, M.; Rogers, R.; Grandinetti, G.;
Dunbar, K. R.; Inorg. Chem. 1998, 37, 6706. (d) Avarvari, N.; Martin,
D.; Fourmigue´, M. J. Organomet. Chem. 2002, 643-644, 292. (e)
Devic, T.; Batail, P.; Fourmigue´, M.; Avarvari, N. Inorg. Chem. 2004,
43, 3136. (f) Avarvari, N.; Fourmigue´, M. Chem. Commun. 2004, 1300.
(3) Smucker, B. W.; Dunbar, K. R. J. Chem. Soc., Dalton Trans. 2000,
1309.
(4) Cerrada, E.; Diaz, C.; Diaz, M. C.; Hursthouse, M. B.; Laguna, M.;
Light, M. E. J. Chem. Soc., Dalton Trans. 2002, 1104.
(5) Pellon, P.; Gachot, G.; Le Bris, J.; Marchin, S.; Carlier, R.; Lorcy,
D. Inorg. Chem. 2003, 42, 2056.
(6) (a) Iwahori, F.; Gohlen, S.; Ouahab, L.; Carlier, R.; Sutter, J.-P. Inorg.
Chem. 2001, 40, 6541. (b) Setifi, F.; Ouahab, L.; Golhen, S.; Yoshida,
Y.; Saito, G. Inorg. Chem. 2003, 42, 1791.
Herein, we report the ability of this redox-active vi-
nylphosphine (P-DTF) to also coordinate a tungsten carbonyl
W(CO)4 fragment either as a monodentate (P) or a bidentate
10.1021/ic0501465 CCC: $30.25
Published on Web 04/08/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 9, 2005 3347

Guerro et al.
) 10.3 Hz), 129.8 (1JPC ) 58.8 Hz), 131.1 (4JPC ) 2.4 Hz), 132.4
(3JPC ) 9.8 Hz), 158.0 (2JPC ) 5.3 Hz). Anal. Calcd for
C18H20BPS2: C, 63.17; H, 5.89. Found: C, 63.19; H, 5.93.
[(4,5-Dimethyl-1,3-dithiol-2-ylidene)methyl]diphenylphos-
phine (2). To a solution of 1 (0.64 g, 1.87 mmol) in 40 mL of dry
and degassed toluene was added (0.21 g, 1.87 mmol) of DABCO.
The medium was heated to 45 °C for 4 h, under nitrogen and the
solvent was evaporated. CH2Cl2 was added to the residue, and after
filtration on silica gel and evaporation of the solvent, the vinylphos-
phine 2 was recrystallized in MeOH as a white powder (550 mg,
88%): mp 125 °C; δH (300 MHz; CDCl3) 1.91 (s, 3H, CH3), 1.92
(s, 3H, CH3), 5.90 (d, 1H, CH, 2JPH ) 2.3 Hz), 7.2-7.5 (m, 10H);
(P,S) ligand. In our earlier study, we found that the oxidative
coupling of cis-Mo(CO)4(P-DTF)2 performed in the presence
of tris(4-bromophenyl)aminium hexachloroantimonate af-
forded the metallacycle cis-Mo(CO)4(P,P-TTFV) in rather
low yield.9 We have therefore explored this chemical
coupling of the dithiafulvenyl cores in the coordination
sphere of the M(CO)4 (M ) Mo, W) fragment in the presence
of various oxidizing agents to improve the overall yield of
the oxidation step. Surprisingly, depending on the oxidizing
agent used, we can indeed increase the yield of the five-
membered metallacycle but also we can favor the formation
of a novel six-membered metallacycle. The structural and
electrochemical properties of the various complexes obtained
are also presented.
δP (121 MHz; CDCl3) -13.2; δC (75 MHz; CDCl3) 13.4 (5JPC
)
2.9 Hz), 13.6, 103.6 (1JPC ) 6.8 Hz), 121.1, 122.1 (4JCP ) 8.7 Hz),
128.4, 132.3, 132.5, 138.5 (1JPC ) 7.5 Hz), 152.6 (2JPC ) 40.6
Hz). Anal. Calcd for C18H17PS2: C, 65.83; H, 5.22; S, 19.53.
Found: C, 65.80; H, 5.18; S, 19.69.
Experimental Section
cis-W(CO)4(P-DTF)2 (3) and cis-W(CO)4(P,S-DTF) (4).
DABCO (0.37 g, 3.3 mmol) was added to a solution of phosphine
borane 1 (1.12 g, 3.3 mmol) in 80 mL of degassed toluene, and
the reaction mixture was heated to 45 °C for 4 h under nitrogen.
cis-W(CO)4(C5H11N)2 (0.76 g, 1,65 mmol) was added to the
medium, and after being stirred for 1 h at 45 °C, the solution became
homogeneous. The reaction mixture was filtered through celite,
which was washed twice with CH2Cl2 (50 mL). The solvent was
removed under reduced pressure, and the residue was chromato-
graphed over silica gel (4:2 pentane/ether) affording 3 (692 mg,
65%) and 4 in 29% yield as yellow powders.
cis-W(CO)4(P-DTF)2 (3): mp 184 °C; δH (300 MHz; CDCl3)
1.71 (s, 6H, CH3), 1.88 (s, 6H, CH3), 5.61 (d, 2H, CH, 2JPH ) 20.1
Hz), 7.30-7.50 (m, 20H); δP (121 MHz; CDCl3) 6.4 (1JPW ) 233
Hz); IR (cm-1) νCdO 1867, 1903, 1930, 2013; HRMS (FAB) calcd
for C40H34O4P2S4W 952.032 4, found 952.032 5. Anal. Calcd for
C40H34O4P2S4W: C, 50.43; H, 3.60; S, 13.46. Found: C, 50.61;
H, 3.66; S, 13.31.
1H NMR and 13C NMR spectra were recorded on Bruker AC
300P spectrometer. Chemical shifts are reported in ppm referenced
1
to TMS for H NMR and 13C NMR and to H3PO4 for 31P NMR.
Melting points were measured using a Kofler hot stage apparatus.
IR were recorded on Biorad IRFTS 175 C. Elemental analyses
results were obtained from the Laboratoire Central de Microanalyze
du CNRS, Lyon, France. Mass spectra were recorded with a
ZABSpec TOF instrument by the Centre Re´gional de Mesures
Physiques de l’Ouest, Rennes, France. Tetrahydrofuran was distilled
from sodium benzophenone. CH2Cl2 was distilled from P2O5.
Toluene was dried over sodium wire. Chromatography was
performed using silica gel Merck 60 (70-260 mesh). Mo(CO)6
and 1,4-diazabicyclo[2.2.2]octane (DABCO) were purchased from
ACROS organics. W(CO)6 was purchased from Aldrich. M(CO)4-
(NHC5H10)2 was prepared from M(CO)6 according to a published
procedure.10 Cyclic voltammetry was carried out on a 10-3
M
solution of TTF derivatives in dichloromethane containing 0.1 M
nBu4NPF6 as supporting electrolyte. Voltammograms were recorded
at 0.1 V s-1 on a platinum disk electrode (A ) 1 mm2). The
potentials were measured versus the saturated calomel electrode.
[[(4,5-Dimethyl-1,3-dithiol-2-ylidene)methyl]diphenylphos-
phine-κP]trihydroboron (1). To a solution of diisopropylamine
(1.01 g, 10 mmol) in dry degassed THF (50 mL) was added
nBuLi (6.25 mL, 10 mmol, from a 1.6 M solution in hexane) at
-20 °C under nitrogen. After the mixture was stirred for 15 min,
Ph2PMeBH3 (2.14 g, 10 mmol) in 10 mL of dry THF was added
to the medium. The reaction mixture was stirred for an additional
30 min at -20 °C, and 4,5-dimethyl-2-piperidin-1-yl-1,3-dithiol-
2-ylium hexafluorophosphate (1.8 g, 5 mmol) was added. The
reaction mixture was allowed to reach room temperature and stirred
for 4 h. Water was added to the medium (50 mL) and the mixture
extracted into 100 mL of CH2Cl2. The organic phase was washed
with water and dried over MgSO4, and 20 g of silica gel was added
to the solution. After filtration and evaporation of the solvent under
reduced pressure, the resulting oil was crystallized by adding diethyl
ether to afford 1 as a white powder (820 mg, 48% yield): mp 138
°C; δH (300 MHz; CDCl3) 0.6-1.8 (brm, 3H, BH3), 1.84 (s, 3H,
cis-W(CO)4(P,S-DTF) (4): mp 188 °C; δH (300 MHz; CDCl3)
2.06 (s, 3H, CH3), 2.11 (s, 3H, CH3), 6.57 (d, 1H, CH, 2JPH ) 2.4
Hz) 7.40-7.60 (m, 10H); δP (121 MHz; CDCl3) 52.7 (1JPW ) 237.2
Hz); IR (cm-1) νCdO 1869, 1886, 1929, 2016; HRMS (FAB) calcd
for C22H17O4PS2W 623.981 5, found 623.982 0. Anal. Calcd for
C22H17O4PS2W: C, 42.32; H, 2.74; S, 10.27. Found: C, 42.38; H,
2.84; S, 10.22.
cis-W(CO)4(P,P-TTFV) (5). cis-W(CO)4(P-DTF)2 (3) (0.29 g,
3 mmol) and (BrC6H4)3NSbCl6 (0.5 g, 6 mmol) were dissolved in
15 mL of dry degassed CH2Cl2, and the solution was heated to
reflux for 1 h under nitrogen. Na2S2O4 (2 g) was added to the
medium, and the reaction mixture was stirred under reflux for an
additional 1 h. Then the medium was allowed to reach room
temperature, washed with water (3 × 10 mL), and dried over Na2-
SO4. The solvent was evaporated, and the crude product was
purified by chromatography on silica gel using an ether/pentane
(1:2) mixture as the eluent to give 5 in 15% yield. Using AgBF4 as
the oxidizing agent, to a solution of 3 (0.13 g, 1.5 mmol) in 10 mL
of dry degassed CH2Cl2 was added AgBF4 (0.05 g, 3 mmol) at 0
°C. The solution was stirred at 0 °C for 2.5 h while the solution
turned to dark red, and then Na2S2O4 (2 g) was added. After 30
min of stirring, the solution was washed with water (2 × 20 mL)
and dried over Na2SO4. Chromatography over silica gel using an
ether/pentane (1:2) mixture as the eluent afforded the desired
product in 30% yield: mp 248 °C; δH (300 MHz; CDCl3) 1.70 (s,
6H, CH3), 2.04 (s, 6H, CH3), 7.10-7.90 (m, 20H); δP (121 MHz;
CDCl3) 41.40 (1JPW ) 226.9 Hz); IR (cm-1) νCdO 1859, 1891, 1906,
2009; HRMS (ESI) [M + Na]+ calcd for C40H32O4NaP2S4W
2
CH3), 1.90 (s, 3H, CH3), 5.64 (d, 1H, CH, JPH ) 7.7 Hz), 7.30-
7.75 (m, 10H); δP (121 MHz; CDCl3) 14.3 (br m); δC (75 MHz;
CDCl3) 12.8, 13.5, 91.5 (1JPC ) 65.6 Hz), 122.0, 124.2, 128.8 (2JPC
(7) Liu, S.-X.; Dolder, S.; Franz, P.; Neels, A.; Stoeckli-Evans, H.;
Decurtins, S. Inorg. Chem. 2003, 42, 4801.
(8) Devic, T.; Avarvari, N.; Batail, P. Chem.sEur. J. 2004, 10, 3697.
(9) Lorcy, D.; Guerro, M.; Pellon, P.; Carlier, R. Chem. Commun. 2004,
212.
(10) Darensbourg, D.; Kump, R. L. Inorg. Chem. 1978, 17, 2680.
3348 Inorganic Chemistry, Vol. 44, No. 9, 2005

DithiafulWenyldiphenylphosphine as a Ligand
Table 1. Crystal Data and Structure Refinement Parameters for 3-6
struct param
empirical formula
Mr
color
3‚C6H14
4
5
6‚0.5CH3OH
C46H34O4P2S4W
1024.76
yellow
C22H17O4PS2W
624.30
yellow
C40H32O4P2S4W
950.69
C40.5H34MoO4.5P2S4
878.8
yellow
orange
cryst system
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
triclinic
P1h
monoclinic
P21/c
11.353(5)
10.863(5)
18.796(5)
90
100.271(5)
90
2280.9(16)
4
triclinic
P1h
triclinic
P1h
11.814(5)
12.332(5)
15.941(5)
78.860(5)
85.905(5)
74.533(5)
2195.7(15)
2
11.581(5)
11.885(5)
15.169(5)
82.590(5)
88.004(5)
70.538(5)
1952.1(13)
2
12.361(5)
17.884(5)
19.837(5)
108.153(5)
97.856(5)
100.075(5)
4016(2)
4
F000
D
1020
1.550
2.936
2.8, 27.52
2; 20
18 192
8860
6601
515
0.041
0.082
1.030
a ) 0.0376
b ) 3.9852
-2.19, 1.512
1208
1.818
5.343
2.6, 30.0
1.6; 48
25 197
6507
4390
272
0.031
0.0471
1.063
a ) 0.0102
b ) 3.2489
-1.245, 1.682
944
1.617
3.295
2.64, 29.99
2; 20
49 686
11 058
6296
460
0.049
0.086
1.021
a ) 0.0308
b ) 4.2778
-1.423, 1.281
1796
1.453
0.655
3.03, 27.5
2; 30
59 157
16 996
9722
939
0.049
0.0892
1.027
a ) 0.0335
b ) 7.2812
-0.527, 0.56
calc (g/cm3)
µ (mm-1
min, θmax (deg)
)
θ
ω frame width (deg); time/frame (s)
tot. no. of measd intensities
no. of unique data
obsd reflcns (I > 2σ(I))
no. of refined variables (n)
R1(F)a
wR2(F)b
GoFc
weighting paramsd
largest diff map hole and peak (e Å-3
)
1/2
2
2
2
2
2
a R1 ) Σn||Fo| - |Fc||/Σn|Fo| (for I > 2σ(I)). b wR2 ) (Σnw(Fo - Fc )2/Σnw(Fo )2) (for I > 2σ(I)). c GoF ) (Σnw(Fo - Fc )2/(n - p))1/2
.
d w )
2
2
2
1/(σ2(Fo ) + (aP)2 + bP); P ) (max(Fo ,0) + 2Fc )/3.
973.006 6, found 973.003 4. Anal. Calcd for C40H32O4P2S4W: C,
50.53; H, 3.39. Found: C, 49.99; H, 3.33.
goniometer positions) was carried out with the help of the
COLLECT program (Nonius, 1998).11a Experimental details of the
data collection have been summarized in Table 1.
Synthesis of Complex 6. A solution of cis-Mo(CO)4(P-DTF)2
(0.5 g, 0.58 mmol) and DDQ (0.35 g, 1.28 mmol) in 25 mL of dry
CH2Cl2 was heated to refux for 30 min under inert atmosphere.
Then Na2S2O4 was added to the medium. The reaction mixture was
washed twice with water, dried over Na2SO4, and concentrated
under reduced pressure. Chromatography over silica gel using an
ether/pentane (1/2) mixture as eluent afforded 6 in 43% yield: mp
205 °C; δH (300 MHz; CDCl3) 1.74 (s, 3H, CH3), 1.78 (s, 3H,
CH3), 1.82 (s, 3H, CH3), 1.91 (s, 3H, CH3), 7.20-8.00 (m, 20H);
δP (121 MHz; CDCl3) 44.2 (2JPP ) 25 Hz), 56.5 (2JPP ) 25 Hz);
IR (cm-1) νCdO 1863, 1901, 1923, 2022; HRMS calcd for
C40H32O4P2S4Mo 863.9712, found 863.9723. Anal. Calcd for
C40H32O4P2S4Mo: C, 55.68; H, 3.74; S, 14.86. Found: C, 55.56;
H, 3.81; S, 14.84.
Finally, the integration process and data reduction were carried
out using the EVAL program (Duisenberg 1998).11b Merging
procedure and additional spherical-type absorption correction were
applied through the SADABS program (G. Sheldrick, 2002).12a
Structure determination was performed with the direct methods
solving program SIR97 (Altomare, 1999),11c which revealed all the
non-hydrogen atoms. The SHELXL program (Sheldrick, 1997)12b
was used to refine the structure. Finally, hydrogen atom were placed
geometrically and held in the riding mode in the least-squares
refinement procedure. Last cycles of the refinement included atomic
positions for all the atoms, anisotropic displacement parameters for
all the non-hydrogen atoms, and isotropic displacement parameters
for all the hydrogen atoms. Details of the final refinements are given
in Table 1 for all compounds.
Synthesis of Complex 7. A procedure similar to that described
above for the molybdenum derivative 6 was used for the synthesis
of 7. Chromatography over silica gel using an ether/pentane (1/2)
mixture as eluent afforded 7 in 20% yield: mp 266 °C (dec); δH
(300 MHz; CDCl3) 1.74 (s, 3H, CH3), 1.78 (s, 3H, CH3), 1.83 (s,
3H, CH3), 1.92 (s, 3H, CH3), 7.10-8.10 (m, 20H); δP (121 MHz;
Results and Disussion
Tungsten Complexes of Dithiafulvenyldiphenylphos-
phine. The tungsten carbonyl complex of the vinylphosphine
(P-DTF) was prepared starting from phosphine borane 1
according to the chemical strategy described in Scheme 1.
Decomplexation of this phosphine borane 1 can be realized
1
CDCl3) 26.7 (JPP ) 20 Hz, JPW ) 231 Hz), 47.6 (2JPP ) 20 Hz,
1JPW ) 247 Hz); IR (cm-1) νCdO 1873, 1891, 1909, 2014; HRMS
(ESI) [M + Na]+ calcd for C40H32O4NaP2S4W 973.006 5, found
973.005 6.
Single-Crystal Structure Determination. A single crystal of
each compound was carefully selected under a polarizing micro-
scope and glued to a thin fiber glass. Single-crystal data collection
was performed at room temperature with a Nonius KappaCCD
diffractometer (Centre de Diffractome´trie, Universite´ de Rennes,
Rennes, France), with Mo KR radiation (λ ) 0.710 73 Å). A crystal-
to-detector distance of 25.0 mm was used for all the crystals, and
data collection strategy (determination and optimization of the
(11) (a) COLLECT: KappaCCD software; Nonius BV: Delft, The
Netherlands, 1998. (b) Duisenberg, A. J. M. Reflections on Area
detectors. Thesis, Utrecht, The Netherlands, 1998. (c) Altomare A.;
Burla M. C.; Camalli M.; Cascarano G.; Giacovazzo C.; Guagliardi
A.; Moliterni A. G. G.; Polidori G.; Spagna R. J. Appl. Crystallogr.
1999, 32, 115-119.
(12) (a) Sheldrick, G. M. SADABS, version 2.03; Bruker AXS Inc.:
Madison, WI, 2002. (b) Sheldrick G. M. SHELX97: Program for the
Refinement of Crystal Structures; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.
Inorganic Chemistry, Vol. 44, No. 9, 2005 3349

Guerro et al.
Scheme 1
with DABCO13 to afford the stable vinylphosphine 2 which
can be either isolated or directly used by adding in situ 0.5
equiv of the cis-W(CO)4(piperidine)2 complex and heating
the medium at 45 °C for 4 h under inert atmosphere. Using
these mild conditions, the tungsten complex 3, cis-W(CO)4-
(P-DTF)2, was isolated in 63% yield while a 92% yield was
obtained for the molybdenum analogue carbonyl complex,
cis-Mo(CO)4(P-DTF)2.9
dentate (P) ligand toward cis-W(CO)4(piperidine)2 and
because of the favorable position of the sulfur toward the
resulting free W coordination site left after the departure of
the second piperidino ligand, as a bidentate (P,S) one in the
formation of the five-membered chelate ring.
To increase the yield of formation of the complex 3, cis-
W(CO)4(P-DTF)2, we modified the experimental procedure
by heating the medium at 55 °C instead of 45 °C. We indeed
obtained a better yield of the W(CO)4(P-DTF)2 complex
(82%), but by increasing the temperature, we also induced
the isomerization on the metal center and obtained, be-
sides the cis-W(CO)4(P-DTF)2 3 (65%), the trans-W(CO)4-
(P-DTF)2 3 (17%) (Scheme 2). The 31P NMR spectrum of
Actually, in addition to this complex 3, we also iso-
lated the monosubstituted tungsten fragment, cis-W(CO)4-
(piperidine)(P-DTF), which upon purification by chroma-
tography on silica gel column afforded a yellow crystalline
1
solid. H NMR reveals the disappearance of the piperidino
group, and the crystal structure of this complex shows that
both the phosphorus and sulfur atoms of the dithiafulve-
nylphosphine 2 are coordinated to the metal affording the
metallacycle 4, cis-W(CO)4(P,S-DTF) (Scheme 1 and Figure
1). The removal of the remaining piperidino ligand using
Scheme 2
Figure 1. Molecular structures of 3, cis-W(CO)4(P-DTF)2 (left), and 4,
cis-W(CO)4(P,S-DTF) (right), showing the atom labeling (50% probability
ellipsoids). Hydrogen atoms and phenyl rings for 3 have been omitted for
clarity.
the two cis and trans isomers shows for each one a singlet
indicating equivalent phosphorus environnements together
with a small doublet due to the coupling of the phosphorus
atom with the 183W isotope. The phosphorus atoms resonate
at 12.5 ppm with a characteristic 1JPW ) 280 Hz for the trans-
mild acidic conditions, such as a chromatography upon silica
gel, is reminiscent of what we previously observed on TTF
derivatives.5 Herein the sulfur atom of the dithiole ring itself,
from the already coordinated dithiafulvene 2, is coordinated
to the tungsten, inducing the formation of a five-membered
metallacyclic ring, cis-W(CO)4(P,S-DTF) (4). It is note-
worthy that the coordination of a dithiole ring through the
sulfur atom was rarely encountered.14 Interestingly, under
our reaction conditions, 2 reacted more readily as a mono-
1
P-W-P isomer and at 6.4 ppm with a JPW ) 233 Hz for
the cis-P-W-P one.15 The cis and trans configurations are
also evident from the 1H NMR spectrum for the vinylogous
proton, which appears as a doublet and resonates at 5.61
ppm (2JPH ) 20 Hz) for the cis and 6.38 ppm (2JPH ) 15
Hz) for the trans. For our purpose, as only the cis isomer
can lead to a coupling reaction upon oxidation in the
(13) Brisset, H.; Gourdel, Y.; Pellon, P.; Le Corre, M. Tetrahedron Lett.
1993, 34, 4523.
(14) Kuroda-Sowa, T.; Hirata, M.; Munakata, M.; Maekawa, M. Chem.
Lett. 1998, 27, 499.
(15) Hirsivaara, L.; Haukka, M.; Pursiainen, J. Inorg. Chem. Commun. 2000,
3, 508.
3350 Inorganic Chemistry, Vol. 44, No. 9, 2005

DithiafulWenyldiphenylphosphine as a Ligand
Table 2. Selected Bond Distances (Å) and Angles (deg) for Compounds 3-5
3, cis-W(CO)4(P-DTF)2
4, cis-W(CO)4(P,S-DTF)
5, cis-W(CO)4(P,P-TTFV)
1.986(7)
W1-C2
1.975(6)
W1-C1
W1-C4
1.994(6)
2.029(6)
2.031(6)
2.5419(16)
2.5486(16)
1.807(5)
1.788(5)
1.340(7)
1.346(7)
1.752(5)
1.745(5)
W-C2
W-C3
W-C4
W-C1
W-S1
1.974(4)
1.982(5)
2.024(5)
2.037(5)
2.4992(12)
2.5068(12)
1.808(4)
1.328(5)
1.785(4)
1.748(4)
W1-C3
1.991(6)
2.026(8)
2.028(8)
2.4814(16)
2.5033(16)
1.835(5)
1.828(5)
1.376(7)
1.477(7)
1.378(7)
1.759(5)
1.755(5)
W1-C3
W1-C4
W1-C2
W1-C1
W1-P1
W1-P1
W1-P2
W1-P2
P1-C131
P2-C221
C131-C132
C221-C222
S201-C222
S202-C222
W-P
P1-C131
P2-C231
C131-C132
C131-C231
C231-C232
S3-C232
S4-C232
P-C30
C30-C31
S1-C31
S2-C31
P1-W1-P2
91.25(5)
119.02(17)
113.88(17)
123.2(4)
128.6(4)
126.1(4)
122.0(4)
111.9(3)
S1-W-P
76.51(3)
106.72(13)
105.70(13)
118.3(3)
128.9(3)
120.6(3)
110.6(2)
P1-W1-P2
79.23(6)
110.21(17)
107.70(17)
121.4(5)
121.1(4)
116.7(4)
121.2(5)
125.2(4)
113.4(4)
126.3(4)
122.5(4)
111.2(3)
C131-P1-W1
C30-P-W
C131-P1-W1
C231-P2-W1
C132-C131-C231
C132-C131-P1
C231-C131-P1
C232-C231-C131
C232-C231-P2
C131-C231-P2
C231-C232-S4
C231-C232-S3
S4-C232-S3
C221-P2-W1
C31-S1-W
C31-C30-P
C30-C31-S2
C30-C31-S1
S2-C31-S1
C132-C131-P1
C222-C221-P2
C221-C222-S202
C221-C222-S201
S202-C222-S201
Table 3. 31P NMR Spectroscopic Data and Oxidation Peak Potentials
in V vs SCE for 2-5
coordination sphere of the M(CO)4 fragment, we did not
pursue in the optimization of the 3 cis isomer formation.
The complexes 3, cis-W(CO)4(P-DTF)2, and 4, cis-W(CO)4-
(P,S-DTF), were crystallized in MeOH.
1
2
compd
δ(31P), ppm
Epa
Epa
29
cis-Mo(CO)4(P-DTF)2
3, cis-W(CO)4(P-DTF)2
4, cis-W(CO)4(P,S-DTF)
cis-Mo(CO)4(P,P-TTFV)9
5, cis-W(CO)4(P,P-TTFV)
-13.2
24.1
6.7
52.7
56.9
41.4
0.73a
0.60a
0.65a
0.97a
0.48
9
1.35a
1.35a
1.57a
1.25a
1.29a
The X-ray crystal structure of 3 and 4 are shown in Figure
1, and selected bond distances and angles are listed in Table
2. Within the complex 3, the two dithiafulvene moieties are
cis coordinated to the metal center via the phosphorus atom.
Phosphorus-tungsten bond lengths are in the usual range
(W1-P1 2.5419(16) and W1-P2 2.5486(16) Å) with a
P1-W-P2 interligand angle of 91.25(5)°. Each dithiole ring
is planar with a distance between the two carbons involved
in the coupling reaction for the formation of the vinylogous
TTF backbone of about 3.78 Å. Concerning complex 4, the
tungsten center is surrounded by the cis-coordinated P,S-
ligand 2; the W-P and W-S distances (W-S1 2.4992(12)
and W-P 2.5068(12) Å) are as expected with a bite angle
of S-W-P 76.51(3)°.16 As seen in Figure 1, the five-
membered ring is not planar and adopts an envelop confor-
mation with the tungsten atom above the plane formed by
the P-CdC-S fragment; moreover, the dithiole ring is not
planar and the folding along the S‚‚‚S axis reaches a value
of 27°. This folding of the dithiole ring is induced by the
metallacycle as for instance in cis-W(CO)4(P-DTF)2 (3) the
two dithiole rings are planar. This can be observed in Figure
1b representing the molecular structure of 4. Coordination
through the sulfur atom introduces also a dissymmetry in
the dithiole ring of 4 with a lengthening of the metallacycle
C-S bond (S1-C31 1.785(4) Å) while the other C-S bond
is in the usual range (S2-C31 1.748(4) Å).
0.49
a Irreversible process.
with those for 2 and cis-Mo(CO)4(P-DTF)2 for comparison.
For 3 and 4, two irreversible oxidation waves are observed
assigned in both cases for the first one to the oxidation of
the dithiafulvene core into the cation radical and for the
second one to the oxidation of the metallic center. It is worth
noting that depending on the coordination mode either as a
monodentate (P) in 3 or as a bidentate (P,S) ligand in 4, the
oxidation peak potential for the dithiafulvene moiety is
significantly affected. Indeed, a positive shift of 320 mV is
observed when the dithiole ring is also coordinated through
the sulfur atom to the tungsten carbonyl fragment, cis-
W(CO)4(P,S-DTF), which exerts an electron-withdrawing
influence. Contrariwise, and as already observed for cis-Mo-
(CO)4(P-DTF)2,9 the oxidation peak potential for 3 is at a
lower potential than the vinylphosphine ligand 2 itself
indicating this time an electron-donating effect of the metallic
center on the dithiafulvene.
Oxidation Studies of the Complexes cis-M(CO)4-
(P-DTF)2. The oxidative coupling of the dithiafulvene
moieties cis-coordinated to the metal center in complexes
cis-M(CO)4(P-DTF)2 (M ) Mo, W) was investigated in the
presence of various oxidizing agents. As shown recently for
the molybdenum derivative, chemical oxidation performed
with tris(4-bromophenyl)aminium hexachloroantimonate,
(BrC6H4)3NSbCl6,17 induced the formation of the bidentate
diphosphine complex with a redox-active vinylogous TTF
The redox behavior of 3 and 4 was investigated by cyclic
voltammetry, and the data are collected in Table 3 together
(16) Hirsivaara, L.; Haukka, M.; Ja¨a¨skela¨inen, S.; Laitinen, R. H.; Niskanen,
E.; Pakkanen, T. A.; Pursiainen, J. J. Organomet. Chem. 1999, 579,
45.
Inorganic Chemistry, Vol. 44, No. 9, 2005 3351

Guerro et al.
Figure 2. Molecular structures of 5, cis-W(CO)4(P,P-TTFV), showing the atom labeling (left) and the distorded conformation of the metallacycle (right)
(50% probability ellipsoids). Hydrogen atoms and phenyl rings have been omitted for clarity.
Scheme 3
Scheme 4
backbone (Scheme 3).9 Thus, the coupling reaction of 3 (cis-
W(CO)4(P-DTF)2) was performed under the same conditions
with 2 equiv of (BrC6H4)3NSbCl6 in dichloromethane under
inert atmosphere at reflux for 1 h followed by the reduction
with Na2S2O4 (Scheme 3).
The intramolecular C-C bond formation between the two
dithiafulvene rings also occurs affording the metallacyle 5,
cis-W(CO)4(P,P-TTFV). As previously demonstrated, the
oxidative coupling of 1,4-dithiafulvenes proceeds through a
radical cation-radical cation mechanism.18 Therefore, we
can postulate that the formation of the metallacycle occurs
according to a similar mechanism: (i) oxidation of the cis-
M(CO)4(P-DTF)2 by (BrC6H4)3NSbCl6 into a bis radical
cation; (ii) coupling of the bis radical cation; (iii) deproto-
nation of the intermediate to afford the vinylogous TTF core
(Scheme 4). In the medium the vinylogous TTF is oxidized
to the dication, which is further reduced by sodium hydro-
sulfite. The 31P NMR spectrum of 5 in CDCl3 shows one
signal at δ 41.40 ppm indicating that the two P atoms are in
the same chemical environnement. Moreover, the phosphorus
atoms resonate at lower field than in the noncyclic complex
3 and a deshielding of 35 ppm is observed indicating a great
degree of steric strain in accordance with the formation of a
five-membered ring.19 Similarly, a deshielding of 32.8 ppm
was observed for the molybdenum metallacycle cis-Mo(CO)4-
(P,P-TTFV).9
5 is shown in Figure 2, and selected bond distances and
angles are listed in Table 2. As previously observed for the
molybdenum derivative, the five-membered ring is not planar
and adopts a half-chair conformation. This distorded con-
formation is due to the steric strains generated by the two
planar dithiole rings with an acute dihedral angle based on
the central C-C bond between the two dithiole rings of
48.77° and the shortest S‚‚‚S contact between the sulfur
atoms of the two dithiole rings of 3.12 Å. Comparison of
the bond lengths within this metallacycle 5 and the starting
complex 3 shows that the intramolecular cyclization causes
some changes notably in the phosphorus-tungsten distances
which are shortened (W1-P1 2.4814(16) and W1-P2
2.5043(16) Å), and the P-C bonds are slightly longer with
The crystal structure confirmed the formation of a met-
allacycle resulting from intramolecular carbon-carbon bond
formation upon oxidation. The X-ray molecular structure of
(17) (a) Ohta, A.; Yamashita, Y. J. Chem. Soc., Chem. Commun. 1995,
1761. (b) Yamashita, Y.; Tomura, M.; Braduz Zaman, M.; Imaeda,
K. J. Chem. Soc., Chem. Commun. 1998, 1657. (c) Yamashita, Y.;
Tomura, M.; Imaeda, K. Tetrahedron Lett. 2001, 42, 4191. (d)
Yamashita, Y.; Tomura, M. J. Solid State Chem. 2002, 168, 427.
(18) (a) Hapiot, P.; Lorcy, D.; Carlier, R.; Tallec, A.; Robert, A. J. Phys.
Chem. 1996, 100, 14823. (b) Guerro, M.; Carlier, R.; Lorcy, D.;
Hapiot, P. J. Am. Chem. Soc. 2003, 125, 3159.
Figure 3. Cyclic voltammetry of cis-W(CO)4(P,P-TTFV) in CH2Cl2-0.1
(19) Garrou, P. E. Inorg. Chem. 1975, 14, 1435.
M NBu4PF6 (scan rate 0.1 V s-1).
3352 Inorganic Chemistry, Vol. 44, No. 9, 2005

DithiafulWenyldiphenylphosphine as a Ligand
Figure 4. Molecular structures of 6 showing the two different molecules A (right) and B (left) and the atom labeling (50% probability ellipsoids). Hydrogen
atoms and phenyl rings have been omitted for clarity.
Scheme 5
Table 4. Selected Bond Lengths (Å) and Angles (deg) for 6
molecule A molecule B
Mo1-C102
Mo1-C104
Mo1-C103
Mo1-C101
Mo1-P101
Mo1-P102
P101-C105
P102-C107
S101-C105
S102-C106
S103-C108
S104-C108
C105-C106
C106-C107
C107-C108
1.981(5)
1.985(6)
2.029(5)
2.037(5)
2.5291(12) Mo2-P202
2.5331(14) Mo2-P201
1.842(4)
1.831(4)
1.762(4)
1.788(4)
1.761(4)
1.753(4)
1.341(6)
1.483(5)
1.361(5)
Mo2-C202
Mo2-C203
Mo2-C204
Mo2-C201
1.977(5)
1.993(6)
2.029(6)
2.043(7)
2.5048(14)
2.5479(16)
1.851(4)
1.820(4)
1.744(5)
1.767(5)
1.787(4)
1.765(5)
1.339(6)
1.501(6)
1.359(6)
P201-C205
P202-C207
S201-C208
S202-C208
S203-C206
S204-C205
C205-C206
C206-C207
C207-C208
a P1-W-P2 interligand angle of 79.23(6)°. Among the
spacer group between the two dithiole rings, the CdC bonds
are longer than in either nonsubstituted or substituted
vinylogous TTF.20
The redox behavior of cis-M(CO)4(P,P-TTFV), M ) Mo9
and W, was investigated by cyclic voltammetry, and the data
are collected in Table 3. For the two complexes two oxidation
waves were observed. The first is reversible and bielectronic
and corresponds to the oxidation of the vinylogous TTF core
into the dication (Figure 3), while the second one is
irreversible and attributable to the oxidation of the metallic
center. The nature of the metallic center does not modify
the oxidation potential of the TTFV core (e.g. E ) 0.48 V
for Mo and E ) 0.49 V for W). The redox behavior of the
vinylogous TTF core in these complexes is closely related
to what was observed for other constrained TTFV’s either
when the central conjugation of the vinylogous TTF is part
of a six-membered ring17a or when there are cyclophane-
like vinylogous TTFs, with a short aliphatic link connecting
the two dithiole rings imposing a similar geometry.18b Indeed,
in all these cases, the presence of steric strain (either by the
link or here by complexation) leads to the concomitant
exchange of two electrons. Another salient feature of
vinylogous TTF concerns the molecular movements associ-
ated with the electron transfer;17b,18b,20 one expects therefore
that oxidation of cis-M(CO)4(P,P-TTFV) would induce
similar conformational changes due to the presence of the
metallacycle.
P101-Mo1-P102
C105-P101-Mo1
C107-P102-C141
C107-P102-C151
C141-P102-C151
C107-P102-Mo1
C106-C105-S101
C106-C105-P101
S101-C105-P101
84.32(4)
P202-Mo2-P201
87.29(4)
116.70(14)
105.5(2)
104.0(2)
98.8(2)
107.44(14)
119.8(3)
120.7(3)
119.0(2)
107.78(13) C205-P201-Mo2
105.15(18) C207-P202-C241
100.63(18) C207-P202-C251
103.80(19) C241-P202-C251
116.55(14) C207-P202-Mo2
120.4(3)
122.5(3)
116.5(3)
C206-C205-S204
C206-C205-P201
S204-C205-P201
C105-C106-C107 126.2(4)
C205-C206-C207 123.3(4)
C105-C106-S102
C107-C106-S102
C108-C107-C106 118.6(3)
C108-C107-P102
C106-C107-P102
C107-C108-S104
C107-C108-S103
S104-C108-S103
118.1(3)
115.4(3)
C205-C206S203
119.2(4).
116.9(3)
C207-C206-S203
C208-C207-C206 116.5(4)
127.1(3)
113.7(3)
128.3(3)
120.4(3)
111.3(2)
C208-C207-P202
C206-C207-P202
C207-C208-S201
C207-C208-S202
S201C208S202
125.3(4)
116.0(3).
128.4(4)
119.9(4)
111.6(2)
reaction,21 but in this case mainly phosphine oxide was
obtained due to the decomplexation of the vinylphosphine 2
from its metal complex. While replacing (BrC6H4)3NSbCl6
by AgBF4 we noticed an improvement of the yield of
formation of the metallacycles, from 25% to 38% for the
molybdenum and from 15% to 30% for the tungsten one. In
both cases, together with the metallacycle we also obtained
the mono(dithiafulvenyl) pentacarbonyl derivative, M(CO)5-
We also investigated the coupling reaction of cis-M(CO)4-
(P-DTF)2 (M ) Mo, W) in the presence of other oxidizing
agents. For instance we replaced (BrC6H4)3NSbCl6 first by
iodine which was known for inducing a similar coupling
(20) Bellec, N.; Boubekeur, K.; Carlier, R.; Hapiot, P.; Lorcy, D.; Tallec,
A. J. Phys. Chem. A 2000, 104, 9750.
(21) (a) Mu¨ller, H.; Salhi, F.; Divisia-Blohorn, B. Tetrahedron Lett. 1997,
38, 3215. (b) Lorcy, D.; Rault-Berthelot, J.; Poriel, C. Electrochem.
Commun. 2000, 2/6, 382.
Inorganic Chemistry, Vol. 44, No. 9, 2005 3353

Guerro et al.
Scheme 6
(P-DTF). In the search for another better oxidizing agent,
we also used 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
(DDQ). Actually, using this reactant, we did not observe the
formation of the expected five-membered metallacyclic ring.
Indeed, analysis of the reaction product by 31P NMR reveals
an AX pattern, at δ 44.2 and 59.5 ppm with a 2J(P,P) of 25
Hz for the molybdenum derivative and at δ 26.7 and 45.6
NSbCl6 > DDQ > AgBF4, does not appear to be the
pertinent parameter for controlling the formation of either
the five- or the six-membered metallacycle. At this stage
we do not have any explanation for this different behavior.
Nevertheless, two plausible mechanisms can be envisioned
for the formation of 6 and 7. As described in the Scheme 6
pathway a, DDQ (E1 ) 0.57 V vs SCE in CH2Cl2) can
oxidize the two dithiafulvene cores into the bis cation radical,
where one radical would be located on the dithiole ring; the
coupling reaction would involve the formation of the six-
membered metallacycle followed by the rearrangement and
the deprotonation leading to the formation of the dithiine
ring. The second pathway, pathway b, would involve first
the oxidation of one dithiafulvene followed by the intramo-
lecular cyclization with release of H+ leading to the six-
membered metallacycle, which is further oxidized and
rearranged into the dithiine followed by the deprotonation.
Actually, this unusual rearrangement was rarely observed
apart from 1,2-bis(1,4-dithiafulven-6-yl)benzene using Br2
as the oxidizing agent.22
2
ppm with a J(P,P) of 20 Hz for the tungsten derivative,
indicating that the two phosphorus atoms are this time in
1
nonequivalent environments. Similarly, H NMR spectra
reveal a dissymmetrical structure with the disappearance of
the vinylogous protons while mass spectrometry gave a
composition similar to the one obtained for the five-
membered metallacycles indicating that herein a coupling
reaction also occurred. Single-crystal X-ray structure deter-
mination provided conclusive structural characterization of
these metallacycles, where the coupling reaction upon
oxidation with DDQ yield novel six-membered metallacycles
6 (Mo) and 7 (W) (Scheme 5 and Figure 4).
The molecular structure of 6 was established by X-ray
diffraction (Figure 4), and selected bond distances and angles
are given in Table 4. Two different molecules, A and B, are
present in the asymmetric unit. In both molecules the
metallacycle adopts a boat conformation with the C bearing
the dithiole unit and the P atom above the plane. In molecule
A, the folded 1,4-dithiine unit is oriented at the opposite
direction of the dithiole while in the same direction for
molecule B. The redox behavior of 6 and 7 was investigated
by cyclic voltammetry in dichloromethane. For these met-
allacycles, only one irreversible oxidation wave was observed
at Epa ) 0.70 V for 6 and Epa ) 0.71 V vs SCE for 7.
It is worth noting that using DDQ as the oxidant the
formation of the 1,4-dithiine ring is favored while with
(BrC6H4)3NSbCl6 or AgBF4 the expected vinylogous TTF
core is formed. Thus, the strength of the oxidant, (BrC6H4)3-
Conclusions
The coordinating ability of the dithiafulvenyl phosphine
ligand toward the tungsten carbonyl fragment W(CO)4 has
been investigated, and we have shown that it could behave
as a monodentate (P) ligand or unexpectedly as a bidentate
(P,S) ligand. Upon oxidation the formation of the vinylogous
TTF core occurs in the coordination sphere of the W(CO)4
fragment, as also observed for the Mo analogue. Through
the simple change of oxidizing agent, the carbon-carbon
bond formation occurring upon oxidation of cis-M(CO)4-
(22) Lakshmikantam, M. V.; Cava, M. P.; Carroll, P. J. J. Org. Chem.
1984, 49, 726. (b) Fre`re, P.; Gorgues, A.; Jubault, M.; Riou, A.;
Gouriou, Y.; Roncali, J. Tetrahedron Lett. 1994, 35, 1991.
3354 Inorganic Chemistry, Vol. 44, No. 9, 2005

DithiafulWenyldiphenylphosphine as a Ligand
(P-DTF)2 can be altered. Although the formation of the
dithiine ring has been noted previously, at this stage no
deductions could be drawn concerning what might drive the
formation of either the five-membered or the six-membered
metallacycle ring. Future investigations on this novel model
of vinylogous tetrathiafulvalene complex will also focus on
the nature of the molecular movement triggered by electron
transfer.
Note Added after ASAP: This article was published
ASAP on April 8, 2005, with a minor error in Scheme 6.
The Web version published on April 11, 2005, and the print
version are correct.
Supporting Information Available: X-ray crystallographic files
in CIF format for complexes 3-6. This material is available free
of charge via the Internet at http://pubs.acs.org.
IC0501465
Inorganic Chemistry, Vol. 44, No. 9, 2005 3355