New procedure for the synthesis of (fulvalene)ditungsten carbonyl halides and cyclopentadienyltungsten carbonyl halide complexes with P-donor nucleophiles

Article abstract of DOI:10.1021/om980180+

The reactions of (η⁵η⁵-C₁₀H₈)W ₂(CO)₆I₂ and (η⁵-C₅H₅)W(CO)₃I with P-donor nucleophiles (L = P(OMe)₃, PPhMe₂, P(n-Bu)₃, PPh₂Me, P(p-tol)₃, P(m-tol)₃, and PCy₃) in the presence of 2 and 1 equiv, respectively, of Me₃NO yield (η⁵:η⁵-C₁₀H₈)W ₂(CO)₄L₂I₂ and (η⁵-C₅H₅)W(CO)₂-LI, respectively, as a mixture of cis/trans isomers. The relative proportion of these isomers is dependent of the stereoelectronic properties of the phosphine ligands. The X-ray structure of (η⁵:η⁵-(C₁₀H₈)W ₂(CO)₆I₂ has been determined.

Full text of DOI:10.1021/om980180+

Organometallics 1998, 17, 3733-3738
3733
New P r oced u r e for th e Syn th esis of
(F u lva len e)d itu n gsten Ca r bon yl Ha lid es a n d
Cyclop en ta d ien yltu n gsten Ca r bon yl Ha lid e Com p lexes
w ith P -Don or Nu cleop h iles
Consuelo Moreno,† Mar´ıa-J ose´ Macazaga,† Rosa-Mar´ıa Medina,†
David H. Farrar,‡ and Salome´ Delgado*,†,§
Departamento de Quı´mica Inorga´nica, Universidad Auto´noma de Madrid, Cantoblanco,
28049-Madrid, Spain, and Lash Miller Chemical Laboratories, University of Toronto,
80 St. George Street, Toronto, Ontario, Canada M5S 3H6
Received March 11, 1998
The reactions of (η5:η5-C10H8)W2(CO)6I2 and (η5-C5H5)W(CO)3I with P-donor nucleophiles
(L ) P(OMe)3, PPhMe2, P(n-Bu)3, PPh2Me, P(p-tol)3, P(m-tol)3, and PCy3) in the presence of
2 and 1 equiv, respectively, of Me3NO yield (η5:η5-C10H8)W2(CO)4L2I2 and (η5-C5H5)W(CO)2-
LI, respectively, as a mixture of cis/trans isomers. The relative proportion of these isomers
is dependent of the stereoelectronic properties of the phosphine ligands. The X-ray structure
of (η5:η5-(C10H8)W2(CO)6I2 has been determined.
In tr od u ction
However, is known that (η5:η5-C10H8)M2(CO)6 (M )
Mo, W) complexes react directly with strongly donating
phosphines, to give the zwitterionic compounds (η5:η5-
C10H8)M2(CO)5L2 (L ) PMe3, dmpm),3 and halo com-
pounds of the type (η5-C5H5)W(CO)2LI and (η5:η5-C10H8)-
Mo2(CO)4L2X2 (L ) phosphines) (X ) Cl, Br, I) have
been prepared by direct substitution of a CO ligand from
the parent dihalides with a phosphine ligand.7
In this paper we report the reactions of (η5-C5H5)W-
(CO)3I and (η5:η5-C10H8)W2(CO)6I2 with a wide variety
of P-nucleophiles with different stereoelectronic proper-
ties, in order to evaluate the influence of the fulvalene
ligand on the reactivity, and we describe a general
method for synthesis of phosphine-substituted (ful-
valene)dimetal carbonyl halide complexes.
Organometallic compounds that incorporate two or
more reactive metal sites in close proximity might
provide access to reaction pathways not available to
mononuclear systems as a result of cooperative elec-
tronic and/or steric effects.1
In contrast to the well-studied cyclopentadienylmetal
carbonyl dimers, the fulvalene-bridged analogues are
expected to show, and have shown in several cases,
enhanced reactivity. This is due, in part, to the ability
of the fulvalene ligand to allow for metal-metal bond
cleavage while inhibiting fragmentation to mononuclear
complexes; the potential for metal-metal cooperativity
is maintained through relative proximity and possibly
by communication through the π-bond system of the
fulvalene ligand.2
The chemistry of the (η5:η5-C10H8)W2(CO)6 complex
has been relatively unexplored3 in comparison with the
molybdenum analogues.4 Unfortunately, direct substi-
tutions of the CO ligands with tertiary phosphines do
not generally ocurr,3,4 in contrast to the cyclopentadi-
enylmetal carbonyl dimers, (η5-C5H5)2W2(CO)6, which
may yield P-donor substituted W-W-bonded dimers (η5-
C5H5)2W2(CO)6-x(PR3)x (x ) 1, 2)5 or disproportionation
products [(η5-C5H5)W(CO)2(PR3)2+][(η5-C5H5)W(CO)3-],6
depending on reaction conditions and the electronic and
steric properties of PR3.
Exp er im en ta l Section
Rea gen ts a n d Gen er a l Tech n iqu es. All manipulations
were carried out by using standard Schlenk vacuum-line and
syringe techniques under an atmosphere of oxygen-free Ar.
All solvents for synthetic use were reagent grade. Diglyme,
pentane, tetrahydrofuran (THF), diethyl ether, and hexane
were dried and distilled over sodium in the presence of
benzophenone ketyl under an Ar atmosphere. Also under Ar
atmosphere, carbon tetrachloride, dichloromethane (DCM),
dichloroethane (DCE), and toluene were dried and distilled
over MgSO4, CaH2, and sodium, respectively. All solvents were
(5) (a) Barnett, K. W.; Treichel, P. M. Inorg. Chem. 1967, 6, 294. (b)
King, R. B.; Pannell, K. H. Inorg. Chem. 1968, 7, 2356. (c) Haines, R.
J .; Nyholm, R. S.; Stiddard, M. H. B. J . Chem. Soc. A 1968, 43. (d)
Haines, R. J .; Marais, I. L.; Nolte, C. R. J . Chem. Soc., Chem. Commun.
1970, 547. (e) Haines, R. J .; Nolte, C. R. J . Organomet. Chem. 1970,
24, 725. (f) Haines, R. J .; Du Preez, A. L.; Marais, I. L. J . Organomet.
Chem. 1971, 28, 97.
(6) For reviews with extensive references to reactions between
Cp2M2(CO)6 and phosphines see: (a) Tyler, D. R. In Organometallic
Radical Processes; Trogler, W. C., Ed.; Elsevier: New York 1990; p
338. (b) Tyler, D. Prog. Inorg. Chem. 1988, 36, 125.
† Universidad Auto´noma de Madrid.
‡ University of Toronto.
§ E-mail: Salome.delgado@.uam.es.
(1) (a) Muetterties, E. L.; Rhodin, R. N.; Band, E.; Brucker, C. F.;
Pretzer, W. R. Chem. Rev. 1979, 79, 91. (b) Marks, T. J . Acc. Chem.
Res. 1992, 25, 57. (c) Su¨ss-Fink, G.; Meister, G. Adv. Organomet. Chem.
1993, 35, 41.
(2) Desbois, M. H.; Astruc, D.; Guillin, J .; Maiot, J . P.; Varret, F. J .
Am. Chem. Soc. 1985, 107, 5280.
(3) (a) Tilset, M.; Vollhardt, K. P. C.; Boese, R. Organometallics
1994, 13, 3146. (b) Tilset, M.; Vollhardt, K. P. C. Organometallics 1985,
4, 2230.
(7) (a) Treichel, P. M.; Barnett, K. W.; Shubkin, R. L. J . Organomet.
Chem. 1967, 7, 449. (b) Kova´cs, I.; Baird, M. C. Organometallics 1995,
14, 4074.
(4) Drage, J . S.; Vollhardt, K. P. C. Organometallics 1986, 5, 280.
S0276-7333(98)00180-0 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 07/30/1998

3734 Organometallics, Vol. 17, No. 17, 1998
Moreno et al.
bubbled with Ar for 1 h after distillation and then stored under
Ar or degassed by means of at least 3 freeze-pump-thaw
cycles after distillation and before use.
δ 5.45 (s, 5H), 7.55 (m, 6H, o-Ph), 7.19 (m, 6H, m-Ph), 2.34 (s,
3H). ); trans δ 5.12 (d, 5H, J PH 1.9 Hz), 7.55 (m, 6H, o-Ph),
7.19 (m, 6H, m-Ph), 2.34 (s, 3H). 31P (CDCl3): cis 28.70 (s);
trans 29.78 (s). Anal. Calcd for C28H26WO2PI: C, 45.68; H,
3.56. Found: C, 44.85; H, 3.79.
The compounds [(η5-C5H5)W(CO)3]2,8 (η5-C5H5)W(CO)3I9 (1),
(η5:η5-C10H8)W2(CO)6,10 (η5:η5-C10H8)W2(CO)6I2 (2), and (η5-
3
C5H5)W(CO)2(PCy3)I11 were prepared according to literature
procedures. The halo derivatives were purified by thin-layer
chromatography (TLC) using CH2Cl2/hexane (1:2) as eluent.
Trimethylamine N-oxide (Aldrich) was sublimed prior to use
8. Yield: 60%. Cis:trans isomer ratio: 40:60%. IR (THF):
νCO 1949 (s), 1875 (vs) cm-1 1H NMR (300 MHz, CDCl3): cis
.
δ 5.44 (s, 5H), 7.33 (m, 12H, Ph), 2.35 (s, 9H); trans δ 5.11 (d,
5H, J PH 1.8 Hz) 7.33 (m, 12H, Ph), 2.35 (s, 9H). 31P (CDCl3):
cis 24.59 (s); trans 29.96 (s). Anal. Calcd for C28H26WO2PI:
C, 45.68; H, 3.56. Found: C, 45.22; H, 3.89.
1
and stored under argon. The H NMR spectra were recorded
on a Bruker AMX-300 or -500 instrument. Chemical shifts
were measured relative to an internal reference of tetrameth-
ylsilane or to residual protons of the solvents for 1H and H3-
PO4 for 31P. Infrared spectra were measured on a Perkin-
Elmer 1650 infrared spectrometer. Elemental analyses were
performed by the Mycroanalytical Laboratory of the University
Auto´noma of Madrid on a Perkin-Elmer 240 B microanalyzer.
Electronic spectra were recorded on a Pye Unicam SP 8-100
UV-visible spectrophotometer. Mass spectra were measured
on a VG-Autospec mass spectrometer for FAB or AIE by the
Mass Laboratory of the University Auto´noma of Madrid.
P r ep a r a tion of (η5-C5H5)W(CO)2LI (L ) P (OMe)3 (3),
P P h Me2 (4), P (n -Bu )3 (5), P P h 2Me (6), P (p -t ol)3 (7),
P (m -tol)3 (8), a n d P Cy3 (9)). Sep a r a tion of Tw o Isom er s.
Meth od A. These compounds were synthesized by a modifica-
tion of the literature method7a previously described for (η5-
C5H5)W(CO)2(PCy3)I.11 A solution of L (0.18 mmol) in THF
(15 mL) was added to a solution of (η5-C5H5)W(CO)3I (0.05 g,
0.11 mmol) in the same solvent (30 mL). The solutions were
refluxed for a period of 1-7 days to produce a mixture of cis
and trans isomers. The reactions were monitored by FTIR
spectroscopy. Upon filtration and removal of the solvent under
reduced pressure, reddish-brown solids were obtained which
were extracted with DCM, and the cis and trans mixtures were
separated and purified by TLC using DCM/hexane (1:2) as
eluent.
9. Yield: 98%. Cis:trans isomer ratio: 95:5%. IR (THF):
νCO 1940 (vs), 1859 (m) cm-1
.
Meth od B. These compounds are also accessible in higher
yields (95%, 93%, 96%, 90%, 80%, 90%, and 99% respectively)
by the same procedure used in the preparation of (η5:η5-(C10H8)-
W2(CO)6L2I2 complexes.
P r ep a r a tion of (η5:η5-C10H8)W2(CO)4L2I2 (L ) P (OMe)3
(10), P P h Me2 (11), P P h 2Me (12), a n d P Cy3 (13)). Tri-
methylamine N-oxide was utilized to chemically oxidize and
remove two CO molecules. The same procedure was followed
in the preparation of all phosphine-substituted (fulvalene)-
ditungsten carbonyl halide complexes. Solutions of 0.12 g (0.13
mmol) of (η5:η5-C10H8)W2(CO)6I2 and 0.26 mmol of L in 25 mL
of THF were prepared. Trimethylamine N-oxide (0.0198 g,
0.26 mmol) was added with vigorous magnetic stirring. The
solutions were stirred until the reactions were seen to be
completed by IR spectroscopy. After ∼10 min, no starting
material remained; the reddish-brown solid was extracted with
DCM and purified by TLC using DCM/hexane (1:2) as eluent.
Solvent removal followed by recrystallization (CH2Cl2-hexane,
at -20 °C) afforded red-brown crystalline products.
10. Yield: 90%. IR (THF): νCO 1964 (s), 1885 (vs) cm-1
.
1H NMR (500 MHz, CDCl3): δ 5.89 (m, Fv), 5.87 (m, Fv), 5.85
(m, Fv), 5.82 (m, Fv), 5.07 (m, Fv), 5.05 (m, Fv), 4.63 (m, Fv),
4.58 (m, Fv), 4.44 (m, Fv), 4.40 (m, Fv), 3.67 (s, 9H). 31P
(CDCl3): 146.72 (s, trans-trans), 145.50 (s, cis-trans), 133.21
3. Yield: 65%. Cis:trans isomer ratio: 10:90%. IR (THF):
ν
CO 1964 (m), 1886 (vs) cm-1 1H NMR (300 MHz, CDCl3): cis
.
(s, cis-trans), 134.80 (s, cis-cis). Anal. Calcd for C20H26
-
δ 5.53 (s, 5H), 3.70 (s, 9H); trans δ 5.39 (d, 5H, J PH 2.0 Hz),
3.70 (s, 9H). 31P (CDCl3): cis 134.16 (s); trans 146.67 (s). Anal.
Calcd for C10H14WO5PI: C, 21.60; H, 2.54. Found: C, 21.39;
H, 2.68.
W2O10P2I2: C, 21.64; H, 2.36. Found: C, 21.50; H, 2.47.
11. Yield: 96%. IR (THF): νCO 1947 (s), 1863 (vs) cm-1
.
1H NMR (500 MHz, CDCl3): δ 6.07 (m, Fv), 5.98 (m, Fv), 5.86
(m, Fv), 5.42 (m, Fv), 5.24 (m, Fv), 5.06 (m, Fv), 5.03 (m, Fv),
5.00 (m, Fv), 4.85 (m, Fv), 4.53(m, Fv), 7.75 (m, 2H, o-Ph), 7.50
(m, 3H, m-Ph and p-Ph), 2.53 (m, Hcis), 2.23 (m, Hcis), 1.96 (d,
4. Yield: 63%. Cis:trans isomer ratio: 25:75%. IR (THF):
νCO 1947 (s), 1861 (vs) cm-1 1H NMR (300 MHz, CDCl3): cis
.
δ 5.41 (s, 5H), 7.75 (m, 2H, o-Ph), 7.55 (m, 3H, m-Ph and p-Ph),
2.10 (m, 6Hcis), trans δ 5.28 (d, 5H, J PH 2.3 Hz,), 7.75 (m, 2H,
o-Ph), 7.55 (m, 3H, m-Ph and p-Ph), 1.94 (d, 6Htrans J PH 13.1
Hz ). 31P (CDCl3): cis 26.21 (s); trans 34.46 (s). Anal. Calcd
for C15H16WO2PI: C, 31.61; H, 2.83. Found: C, 30.90; H, 2.95.
5. Yield: 55%. Cis:trans isomer ratio: 60:40%. IR (THF):
H
trans, J PH 13.1 Hz ). 31P (CDCl3): 34.72 (s, trans-trans), 33.10
(s, cis-trans), 25.90 (s, cis-trans), 24.50 (s, cis-cis). Anal.
Calcd for C30H30W2O4P2I2: C, 31.66; H, 2.66. Found: C, 31.52;
H, 2.72.
12. Yield: 97% . IR (THF): νCO 1950 (vs), 1866 (s) cm-1
.
1H NMR (500 MHz, CDCl3): δ 5.80 (m, 2H, ring-4), 5.75 (m,
2H, ring-5), 5.27 (m, 1H, ring-2), 5.20 (m, 2H, ring-5), 5.16 (m,
4H, ring-4 and -5), 5.12 (m, 2H, ring-4), 5.01 (m, 2H, ring-5),
4.95 (m, 5H, ring-1 and -3), 4.91 (m, 1H, ring-3), 4.89 (m, 3H,
ring-2 and -4), 4.76 (m, 2H, ring-5), 4.72 (m, 4H, ring-1), 4.69
(m, 1H, ring-3), 4.58 (m, 1H, ring-3), 7.47 (m, 32H, o-Ph), 7.39
(m, 48H, m-Ph and p-Ph), 2.51 (s, Me), 2.48 (d, Me), 2.46 (s,
Me), 2.41 (d, Me), 2.36 (s, Me), 2.33 (s, Me). 31P (CDCl3): 10.40
(s, trans-trans), 10.13 (s, cis-trans), -4.44 (d, cis-cis meso
and dl), -4.61 (s, cis-trans). Anal. Calcd for C40H34W2-
O4P2I2: C, 38.06; H, 2.72. Found: C, 37.93; H, 2.84.
νCO 1946 (vs), 1856 (s) cm-1 1H NMR (300 MHz, CDCl3): cis
.
δ 5.48 (s, 5H), 1.56 (s, 6H), 1.43 (s, 12H), 0.96 (s, 9H); trans δ
5.27 (d, 5H, J PH 1.9 Hz), 1.56 (s, 6H), 1.43 (s, 12H), 0.96 (s,
9H). 31P (CDCl3): cis 49.82 (s); trans 58.25 (s). Anal. Calcd
for C19H32WO2PI: C, 35.98; H, 5.09. Found: C, 35.44; H, 5.12.
6. Yield: 60%. Cis:trans isomer ratio: 80:20%. IR (THF):
νCO 1950 (vs), 1870 (s) cm-1 1H NMR (300 MHz, CDCl3): cis
.
δ 5.37 (s, 5H), 7.75 (m, 4H, o-Ph), 7.51 (m, 6H, m-Ph and p-Ph),
1.60 (s, 3H); trans δ 5.08 (d, 5H, J PH 2.1 Hz), 7.75 (m, 4H, o-Ph),
7.51 (m, 6H, m-Ph and p-Ph), 1.60 (s, 3H). 31P (CDCl3): cis
-4.68 (s); trans 10.65 (s). Anal. Calcd for C20H18WO2PI: C,
38.00; H, 2.87. Found: C, 37.25; H, 2.95.
13. Yield: 95%. IR (THF): νCO 1941 (vs), 1858 (s) cm-1
.
1H NMR (300 MHz, CD2Cl2): δ 5.85 (m, Fv), 5.82 (m, Fv), 5.53
(m, Fv), 5.44 (m, Fv), 5.39 (m, , Fv), 5.25 (m, Fv), 5.21 (m, Fv),
4.71 (m, Fv), 1.43 (m, Cy), 1.89 (m, Cy). 31P (CD2Cl2): 52.30
(s, cis-cis meso and dl). Anal. Calcd for C50H74W2O4P2I2: C,
42.22; H, 5.24. Found: C, 42.09; H, 5.36.
7. Yield: 50%. Cis:trans isomer ratio: 30:70%. IR (THF):
νCO 1948 (s), 1874 (vs) cm-1 1H NMR (300 MHz, CDCl3): cis
.
(8) Birdwhistell, R.; Hackett, P.; Manning, A. R. J . Organomet.
Chem. 1978, 157, 239.
(9) Abel, E. W.; Singh, A.; Wilkinson, G. J . Chem. Soc. 1960, 1321.
(10) Vollhard, K. P. C.; Weidman, T. W. Organometallics 1984, 3,
82.
(11) Marcos, M. L.; Moreno, C.; Macazaga, M. J .; Medina R. M.;
Maderuelo, R.; Delgado, S.; Gonza´lez-Velasco, J . J . Organomet Chem.
1998, 555, 57.
X-r a y Diffr a ction An a lysis of (η5:η5-C10H8)Mo2(CO)6I2
(2). Orange, plate-shaped crystals of (η5:η5-C10H8)W2(CO)6I2,
2, are obtained by recrystallization of the complex from CH2-
Cl2/hexane mixtures. Intensity data were collected on a
Siemens P4 diffractometer using graphite-monochromated Mo

(Fulvalene)ditungsten Carbonyl Halides
Organometallics, Vol. 17, No. 17, 1998 3735
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 1
Ta ble 2. Bon d Len gth s [Å] a n d An gles [d eg] for 1a
W-C(2)
W-C(1)
W-C(3)
W-C(5)
W-C(6)
W-C(4)
W-C(7)
W-C(8)
W-I
1.992(9)
1.997(8)
2.019(9)
2.304(7)
2.324(8)
2.337(7)
2.364(8)
2.375(7)
2.852(3)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
C(4)-C(8)
C(4)-C(5)
C(4)-C(4′)
C(5)-C(6)
C(6)-C(7)
C(7)-C(8)
1.129(10)
1.157(10)
1.127(10)
1.417(10)
1.422(10)
1.48(2)
1.443(11)
1.422(11)
1.403(11)
empirical formula
fw
C16H8I2O6W2
917.72
temp
173(2) K
wavelength
cryst system
space group
unit cell dimens
0.710 73 Å
triclinic
P1h
a ) 7.063(7) Å, R ) 82.14(8)°
b ) 7.789(7) Å, â ) 85.97(8)°
c ) 8.927(2) Å, γ ) 79.45(7)°
477.7(8) Å3, 1
C(2)-W-C(1)
C(2)-W-C(3)
C(1)-W-C(3)
C(1)-W-I
76.5(3)
112.5(4)
79.3(4)
133.6(2)
76.2(2)
77.5(3)
O(3)-C(3)-W
175.4(8)
107.7(7)
126.0(9)
126.2(9)
108.0(7)
106.7(7)
108.9(7)
108.7(7)
V, Z
D(calcd)
abs coeff
C(8)-C(4)-C(5)
C(8)-C(4)-C(4′)
C(5)-C(4)-C(4′)
C(4)-C(5)-C(6)
C(7)-C(6)-C(5)
C(8)-C(7)-C(6)
C(7)-C(8)-C(4)
3.19 Mg/m3
15.290 mm-1
F(000)
406
C(2)-W-I
cryst size
θ range for data collcn
limiting indices
0.02 × 0.03 × 0.09 mm
C(3)-W-I
O(1)-C(1)-W
O(2)-C(2)-W
2.68-32.23°
178.0(7)
175.9(8)
0 e h e 9, -10 e k e 10,
-12 e l e 12
2990
a
reflcns collcd
Symmetry transformations used to generate equivalent at-
indepdt reflcns
2781 [R(int) ) 0.0346]
full-matrix least-squares on F2
2781/0/118
oms: -x + 1, -y + 1, -z.
refinement method
data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
largest diff peak and hole
0.935
R1 ) 0.0363, wR2 ) 0.0747
R1 ) 0.0496, wR2 ) 0.0777
1.16 and -1.31e‚Å-3
KR radiation. The unit cell dimensions were determined and
refined using the positions of 46 high-angle reflections (20° <
2θ < 52°). The intensities of three standard reflections
measured every 97 reflections showed no decay during data
collection. The cell unit parameters and intensity data
provided strong evidence for the centric space group P1h. The
structure was successfully solved and refined in this space
group. Lorentz, polarization, and background corrections were
applied to the data using the Seimens P4 software.12 The
position of the W atom was solved by the Patterson method,
and the remaining non-H atoms were located by successive
difference Fourier syntheses. Non-hydrogen atoms were
refined anisotropically by full-matrix least-squares techniques
on F2. The H-atom positions were calculated, and the atoms
were constrained as riding atoms with U isotropic 20% larger
than the corresponding C-atom. No secondary extinction
correction was applied to the data. All calculations were
performed using SHELXTL version 5 on a personal com-
puter.12
F igu r e 1. View of molecule 2 with 25% probability
ellipsoids drawn for W, C, and O. For clarity, H atoms are
represented as open spheres.
not observe thermal decomposition of (η5-C5H5)W(CO)3I,
in the presence of phosphine, to [(η5-C5H5)W(CO)3]2.
When these reactions were carried out in presence of 1
equiv of Me3NO, they proceeded in predictable fashion
to give only monosubstituted species as final product
in high yield (∼93%) (eq 1). This new method for
Selected experimental details of the X-ray determination are
given in Table 1, and final positional parameters are given in
the Supporting Information. Anisotropic thermal parameters
and hydrogen atom parameters are available as Supporting
Information. Table 2 contains selected bond distances and
angles. Figure 1 presents a molecular diagram of 1.
Resu lts a n d Discu ssion
P h osph in e Su bstitu tion Reaction s of (η5-C5H5)W-
(CO)3I a n d (η5:η5-C10H8)W2(CO)6I2. Phosphine-sub-
stituted cyclopentadienyltungsten carbonyl halo com-
pounds (η5-C5H5)W(CO)2LI (3-9) (L ) P(OMe)3, PPhMe2,
P(n-Bu)3, PPh2Me, P(p-tol)3, P(m-tol)3, and PCy3) were
readily prepared by direct thermal substitution of a CO
ligand in moderate yield (∼50%) using a modification
of the traditional method.7a In these reactions the only
product obtained was a covalent monosubstituted de-
rivative, and neither disubstitution (η5-C5H5)W(CO)L2I
nor ionic (η5-C5H5)W(CO)L2+I- products were formed.
All reactions were completed in ∼1-7 days on heating
to 90 °C. During the course of these reactions we did
synthesis of organometallic complexes with P-donor
ligands has clear advantages over the traditional method
previously used, namely, mild conditions, short reaction
times, higher yields, and no requirement of excess
ligand. In order to compare the efficiency of this new
procedure, we have gathered the yields and conditions
of both methods in Table 3.
Phosphine-substituted (fulvalene)dimolybdenum car-
bonyl dihalo compounds containing PPh3, PCy3, and
PXy3 are readily prepared, under thermal conditions,
by direct substitution of a CO ligand at each Mo center
(12) Sheldrick, G.M. SHELXTL/ PC, Users Manual, Siemens Ana-
lytical X-ray Instruments Inc.: Madison, WI, 1990.

3736 Organometallics, Vol. 17, No. 17, 1998
Moreno et al.
Ta ble 3. Com p a r ison of Me3NO (A) a n d Dir ect
Th er m a l (B) Su bstitu tion Meth od s in th e
(η5:η5-C10H8)W2(CO)4L2I2 Syn th esis
compd
method
time
yield (%)
3
3
4
4
5
5
6
6
7
7
8
8
9
9
A
B
A
B
A
B
A
B
A
B
A
B
A
B
10 min
2 days
5 min
1 day
5 min
95
65
93
63
96
55
90
60
80
50
90
60
99
98
3 days
5 min
3 days
10 min
7 days
12 min
7 days
15 min
7 days
of the parent dihalides.7b These substitution reactions
are facile and with bulky ligands possible to complete
in ∼10 min-2 h on heating to 110 °C. Surprisingly,
contrary to what was expected, when we treated (η5:η5-
C10H8)W2(CO)6I2 with PPhMe2, PPh2Me, or PCy3 under
thermal conditions, no reaction was observed. Interest-
ingly, while a considerable amount (<40%) of (η5:η5-
C10H8)Mo2(CO)6I2 decomposed to (η5:η5-C10H8)Mo2(CO)6
under thermal conditions in the presence of added
phosphine,7b we have found that the analogous (η5:η5-
C10H8)W2(CO)6I2 does not decompose thermally in both
THF at ∼80 °C or toluene at ∼110 °C for a period of 5
days. In order to obtain phosphine-substituted (ful-
valene)ditungsten carbonyl dihalo we have used a new
general procedure of synthesis using Me3NO to remove
one CO molecule at each metal center of the dihalide
complexes. These reactions take place easily under mild
conditions, and (η5:η5-C10H8)W2(CO)4L2I2 (10-13) (L )
P(OMe)3, PPhMe2, PPh2Me, and PCy3) complexes were
readily obtained by reaction of (η5:η5-C10H8)W2(CO)6I2
with P-donor ligands in the presence of 2 equiv of
trimethylamine N-oxide (eq 2).
F igu r e 2. Schematic representation of the two and four
different stereoisomers of (η5-C5H5)W(CO)3LI and (η5:η5-
C
10H8)W2(CO)4L2I2, respectively.
The complexes (η5-C5H5)W(CO)2LI may exist as a
mixture of cis and trans isomers (Figure 2). The relative
proportion of these isomers depends markedly on the
nature of the phosphorus ligands and the method of
preparation as well as the solvent.13 The identity of the
isomers was proven according to well-established in-
frared and NMR criteria.13a,14 The higher frequency
(symmetric) CO stretching vibration is more intense
than the lower frequency (antisymmetric) stretch for the
cis isomers, while the opposite is true for the trans
isomers. When L ) PCy3,11 P(n-Bu)3, and PPh2Me, the
cis isomer is in high proportion, while for L ) P(OMe)3,
PPhMe2, P(p-tol)3, and P(m-tol)3 is the trans isomer.
These isomers may be readily distinguished by the
characteristic (η5-C5H5) resonances in the NMR spec-
trum. The 1H NMR spectra show that the monosub-
stituted complexes exist as a mixture of two isomers;
the resonances due to the (η5-C5H5) protons of cis
isomers are found as a singlet at ca. 5.40 ppm, while
those due to the trans isomers consist of a 1:1 doublet,
at ca. 5.20 ppm (J PH ) 1.8 Hz), due to coupling with
phosphorus (Experimental Section). The ratio of the
isomers can be easily calculated from the integrals of
these cis and trans resonances and is dependent on the
electronic as well as the steric factors of the ligands.
For the P(OMe)3 and PCy3 ligands the steric effects are
predominant; thus, for the P(OMe)3 ligand, with the
smaller cone angle (θ ) 107°),15 the trans isomer is
predominant, while for the PCy3 ligand, with the greater
cone angle (θ ) 170°), the cis isomer is favored. For
the rest of the ligands, PPhMe2, P(n-Bu)3, PPh2Me, P(p-
tol)3, and P(m-tol)3, the electronic effects are an impor-
tant contributing factor in determining the equilibrium
ratio of isomers, but they do not always dominate with
regard to conformational preference. It thus appears
that steric factors must also be responsible in large
measure for the isomer ratios observed. The cis and
The complexes 3-9 and 10-13 were isolated as
brown-reddish solids. They are very air sensitive. The
fulvalene derivatives are very insoluble in hexane,
toluene, or diethyl ether while the cyclopentadienyl ones
exhibit a high solubility.
The IR spectra of these complexes exhibit two carbo-
nyl stretching bands at ca. 1960 and 1850 cm-1 (see
Experimental Section), characteristic of terminal car-
bonyl ligands. As expected, the νCO stretching frequen-
cies depend on the nature of the substituents and
become greater when the nucleophilic basicity of the
P-donor ligands decreases.
(13) (a) Faller, J . W.; Anderson, A. S. J . Am. Chem. Soc. 1970, 92,
5852. (b) Beach, D. L.; Barnett, K. W. J . Organomet. Chem. 1975, 97,
C27.
(14) (a) Manning, A. R. J . Chem. Soc. A 1967, 984. (b) Beach, D. L.;
Dattilo, M.; Barnett, K. W. J . Organomet. Chem. 1977, 140, 47.
(15) Tolman, C. A. Chem. Rev. 1977, 77, 313.

(Fulvalene)ditungsten Carbonyl Halides
Organometallics, Vol. 17, No. 17, 1998 3737
signals in the range 5.80-4.58 ppm for the fulvalene
resonances, 4 of them completely overlapping at 5.16,
4.95 and 4.89 ppm. Figure 3 shows the COSY spectrum
of this complex, including the normal (1D) spectrum for
comparison of the diagonal connectivities; the protons
corresponding to each of the fulvalene rings (Figure 3)
can be distinguished and assigned unambiguously
(Experimental Section). The ratio of trans-trans, cis-
trans, cis-cis (meso), and cis-cis (dl) was found to be
11:44:22:22 on the basis of integrals. 31P NMR spectrum
of 12 exhibits five resonances at δ 10.4 (trans), 10.1 (cis-
trans), -4.4 and -4.5 (cis-cis), and -4.6 (cis-trans).
1
The H NMR spectrum of 13 shows 8 fulvalene signals
corresponding to two different rings of two different
fulvalene systems, cis-cis (meso) and cis-cis (dl) iso-
mers, in which the halves are spectroscopically identical
(Experimental Section). In agreement with this, the 31
P
NMR spectrum of 13 exhibits only one singlet at 52.30
ppm. 1H NMR spectra 10 and 11 exhibit 10 fulvalene
signals corresponding to five different rings of the four
isomers. In accordance with this, the 31P NMR spectra
exhibit four resonances at δ 146.7 (trans-trans), 145.5
(cis-trans), 133.2 (cis-trans), 134.8 (cis-cis) and 34.7
(trans-trans), 33.1 (cis-trans), 25.9 (cis-trans), and
24.5 (cis-cis), respectively. The isomer ratios of trans-
trans, cis-trans, cis-cis (meso), and cis-cis (dl) for 10
and 11 were found to be 66:30:4:4 and 36:50:7:7,
respectively, on the basis of integrals. The cis:trans
ratios found for (fulvalene)ditungsten complexes are
similar to that for cyclopentadienyltungsten analogous
compounds.
F igu r e 3. COSY experiment for 12 in CDCl3.
trans isomers can be easily separated by TLC using
DMC/hexane (1:2) as eluent. The complexes are stable
with respect to isomerization both in the solid state and
in solution at low temperature. However, when solu-
tions of the pure cis and trans isomers in THF are
heated to 70 °C, rapid isomerization occurs, while at 30
°C the isomerization proceeds more slowly. The 31P
NMR spectra at room temperature exhibit two singlets
assigned to the cis and trans isomers (Experimental
Section). The ratio of cis:trans isomers obtained from
the integrals of these resonances agreed reasonably well
Preliminary results carried out in our laboratory have
revealed that the (fulvalene)dimolybdenums (η5:η5-
C10H8)Mo2(CO)6I2 and (η5:η5-C10H8)Mo2(CO)6 reacts with
PCy3 and PMe3, respectively, in the presence of Me3-
NO under mild conditons to give the disubstituted17 and
zwitterion18 products, respectively. All these results
show that this method is a very efficient and general
way to obtain disubstituted fulvalene or cyclopentadi-
enyl complexes.
1
with that obtained from H NMR data.
The compounds (η5:η5-C10H8)W2(CO)4L2I2 may exist
as four different geometrical isomers (not including
enantiomers), trans-trans, cis-trans (d,l), cis-cis (meso),
and cis-cis (d,l) (cis-cis isomers contain two chiral
centers)3 (Figure 2). The compounds have very similar
infrared spectra in the 2100-1800 cm-1 region. When
L ) PPh2Me and PCy3, the more intense the two
absorptions due to the two CO stretching vibrations, the
higher the frequency (the intensity ratio is consistent
with basically the cis geometry), while when L )
P(OMe)3 and PPhMe2, the lower frequency gives rise to
the more intense absorption in the IR spectrum (basi-
cally trans geometry). The 1H NMR data for these
complexes are listed in the Experimental Section. The
spectra have been assigned on the basis of chemical
shift, integrals, spin-spin coupling information, and
two-dimensional homonuclear correlation spectroscopy
Descr ip tion of th e Cr ysta l a n d Molecu la r Str u c-
tu r e of (η5:η5-C10H8)W2(CO)6I2 (2). The crystal struc-
ture consists of one discrete molecule of 2 per unit cell.
Complex 2 possesses a crystallographically imposed
center of inversion. The two W(CO)3I units are on
opposite sides of a fulvalene ligand as shown in Figure
1. The fulvalene ligand adopts the 1,1′-(η5:η5) binding
mode, and the W centers have a four-legged piano stool
structure (square pyramidal). The dihedral angle be-
tween the two Cp planes of the fulvalene ligand is 0°
(symmetry imposed). In 2, the C-C bridgehead dis-
tance, C(4)-C(4′) (1.48(2) Å), and the mean C)O bond
length (1.138(18) Å) are normal.19 The W-Cp ring
carbon distances range from 2.304(7) to 2.375(7) Å; these
values are consistent with W-Cp ring carbon distances
seen in other compounds. The W-I distance, 2.852(3)
Å, also is normal.19
1
(COSY and NOESY).16 The H NMR spectra can give
rise to 18 signal due to fulvalene proton rings (nine R-
and â-hydrogen sites). Since the substituted cyclopenta-
dienylmolybdenum13b and -tungsten carbonyl halides
3
and (η5:η5-C10H8)Mo2(CO)4(PMe3)2H2 are fluxional,
facile interconversion of the various cis and trans
isomers of (η5:η5-C10H8)W2(CO)4L2I2 was also antici-
pated. For L ) PPh2Me (12) the 1H NMR shows 14
(17) Moreno, C.; Gomez-Escudero, J . L.; Marcos, M. L.; Macazaga,
M. J .; Medina, R.; Gonza´lez-Velasco, J .; Delgado, S. Unpublished work.
(18) Moreno, C.; Marcos, M. L.; Macazaga, M. J .; Medina R. M.;
Farrar, D. H.; Gonza´lez-Velasco, J .; Delgado, S. Organometallics,
submitted for publication.
(19) Allen, F. H.; Kennard, O. Chem. Des. Autom. News 1993, 8,
31.
(16) (a) Kessler, H.; Gehrke, M.; Griesinger, C. Angew. Chem., Int.
Ed. Engl. 1988, 27, 490. (b) Martin, G. E.; Zektler, A. S. In Two-
Dimensional NMR Methods for Establishing Molecular Connectivity;
VCH: New York, 1988.

3738 Organometallics, Vol. 17, No. 17, 1998
Moreno et al.
Su p p or tin g In for m a tion Ava ila ble: Tables of X-ray
data, complete positional and thermal parameters, and bond
distances and angles (5 pages). Ordering information is given
on any current masthead page.
Ack n ow led gm en t. We express our great apprecia-
tion of the financial support from the DGICYT (Project
PB 91-0003) of Spain. Acknowledgments are made (by
D.H.F.) to the Natural Sciences and Engineering Re-
search Council (NSERC) of Canada for equipment
funds. Alan Lough is thanked for his technical as-
sistance regarding the X-ray structure determination.
OM980180+