Comparative reactivity study of cyclopentadienyl and fulvalene molybdenum complexes

Article abstract of DOI:10.1016/S0020-1693(00)00357-1

The reactions of cis-1,1′-[η⁵:η⁵- (C₅H₃CO₂Me)₂]Mo₂ (CO)₆ (1), in the presence of 1 equiv. of Me₃NO, and [(η⁵-C₅H₄CO₂

Full text of DOI:10.1016/S0020-1693(00)00357-1

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Inorganica Chimica Acta 312 (2001) 139–150
Comparative reactivity study of cyclopentadienyl and fulvalene
molybdenum complexes
Consuelo Moreno, Avelina Arnanz, Salome´ Delgado *
Departamento de Qu´ımica Inorga´nica, Facultad de Ciencias, Uni6ersidad Auto´noma de Madrid, Cantoblanco, 28049 Madrid, Spain
Received 24 June 2000; accepted 18 October 2000
Abstract
The reactions of cis-1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)6 (1), in the presence of
1
equiv. of Me3NO, and [(h5-
C5H4CO2Me)Mo(CO)3]2 (2) with dppe produce CO labilization and formation of the dinuclear zwitterions trans-1,1%-[h5:h5-
(C5H3CO2Me)2]Mo2(CO)5(dppe) (3) and disproportionation species [(h5-C5H4CO2Me)Mo(CO)2(dppe)]+ [(h5-C5H4CO2Me)-
Mo(CO)3]− (4), respectively. Using the same method, the reactions of trans-1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)6I2 and (h5-
C5H4CO2Me)Mo(CO)3I with PPh3 in the presence of 1 and 2 equiv. of Me3NO yield trans-1,1%-[h5:h5-(C5H3CO2Me)2]-
Mo2(CO)4(PPh3)2I2 (5) and (h5-C5H4CO2Me)Mo(CO)2(PPh3)I (6). The reactions of the several anionic carbonyl species {trans-
1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)6}2−, [(h5:h5-C10H8)W2(CO)6]2− and [(h5-C5H4CO2Me)Mo(CO)3]− with S2Ph2 give rise to
the thiolate–fulvalene complexes cis-1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)4(m-SPh)2 (7) and (h5:h5-C10H8)W2(CO)6(SPh)2 (8) and
the thiolate-bridged dimer [(h5-C5H4CO2Me)Mo(CO)(m-SPh)]2 (9). Treatment of 6 with 1 equiv. of HCꢀCꢁCꢀCH and with
(h5-C5H5)Mo(CO)(dppe)(CꢀCꢁCꢀCH), in the presence of CuI at room temperature, afford the cyclopentadiene complexes
(h5-C5H4CO2Me)Mo(CO)2(PPh3)(CꢀCꢁCꢀCH) (10) and (h5-C5H4CO2Me)(PPh3)(CO)2Moꢁ(CꢀCꢁCꢀC)ꢁMo(CO)(dppe)(h5-C5H5)
(11), respectively. The reaction of (h5-C5H5)Mo(CO)(dppe)(CꢀCꢁCꢀCH) with Co2(CO)8 yields [Co2{m-HC2CꢀC[Mo(CO)(dppe)-
(h5-C5H5)]}(CO)6] (12). All the new compounds have been characterized by analytical and spectroscopic methods. © 2001 Elsevier
Science B.V. All rights reserved.
Keywords: Fulvalene complexes; Cyclopentadiene complexes; Acetylene complexes; Molybdenum complexes
1. Introduction
metals, few comparative studies are found on related
fulvalene and cyclopentadienyl complexes [8]. While
phosphine-substituted cyclopentadienyltungsten or
molybdenum carbonyl halocompounds (h5-C5H5)M-
(CO)2LI and phosphine-substituted fulvalenedimolyb-
denum carbonyl dihalocompounds (h5:h5-C10H8)-
Mo2(CO)4L2I2 (L=PPh3, PCy3 and PXy3) were readily
prepared by direct thermal substituton of a CO ligand
[9], the phosphine-substituted fulvalene–ditungsten car-
bonyl dihalocompounds can only be prepared under
mild conditions by a new general procedure of synthesis
using Me3NO to remove one CO molecule at each
metal center of the dihalide complexes [8a]. Whereas
the reactions of molybdenum and tungsten cyclopenta-
dienyl carbonyl complexes with thiolate (RS−) ligands
form a well-defined subset among organometallic com-
pounds [10,11], and are primarily of two general types
with formulas (h5-C5H5)M(CO)3(SR), [(h5-C5H5)-
M(CO)2(m-SR)]2 (M=Mo, W) and [(h5-C5H5)Mo-
Bimetallic fulvalene complexes have centered special
attention over the last few decades [1–6]. The chemical
behaviour of fulvalene carbonyl metal complexes is
expected to differ from that of their cyclopentadienyl
metal mononuclear and dimer analogues for several
reasons. One of these reasons 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 p-bond
system of the fulvalene [7]. Although transition-metal
fulvalenyl complexes have been synthetized with many
* Corresponding author. Fax: +34-913-974 833.
E-mail address: salome.delgado@uam.es (S. Delgado).
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(00)00357-1

140
C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
(CO)(m-SR)]2 [10], the reactivity of fulvalene metal com-
plexes, in our knowledge, has been poorly studied [10f].
On the other hand, complexes in which sp carbon
chains span transition metal end-groups are attracting
increasing attention [12–15]. These wire like, unsatu-
rated linear assemblies offer aesthetic appeal, a variety
of interesting fundamental properties, and intriguing
possibilities for molecular-level devices [16]. Specific
properties of transition metal complexes result primar-
ily from the ability of the metal to participate in
p-delocalization, as well as the potential for interaction
of the transition metal d-orbitals with the conjugated
p-orbitals of the unsaturated carbon chains [17–20]. In
order to make a comparative study between fulvalene
and cyclopentadienyl complexes, in this paper we report
the reactions of [h5:h5-(C5H3CO2Me)2]Mo2(CO)6 (1)
and [(h5-C5H4CO2Me)Mo(CO)3]2 (2) with dppe and
thiolate ligands as Ph2S2 and the synthesis of s- and
p-acetylene organometallic complexes.
measured relative either to an internal reference of
tetramethylsilane or to residual protons of the solvents.
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 microanalyser. Electronic spectra were recorded
on a Pye Unicam SP 8-100 UV-Vis 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.
2.2. Synthesis of
trans-1,1%-[p5:p5-(C5H3CO2Me)2]Mo2(CO)5(dppe) (3)
Using the new general method for the synthesis of
[h5:h5-(C5H3CO2Me)2]Mo2(CO)5L2 [8c], trimethylamine
N-oxide is used to chemically oxidize and remove one
CO molecule. A solution of 0.20 g (0.32 mmol) of
[h5:h5-(C5H3CO2Me)2]Mo2(CO)6 (1) (cis isomer) and
0.13 g (0.32 mmol) of dppe in 25 ml of THF was
prepared. Trimethylamine N-oxide 0.036 g (0.32 mmol)
was added with vigorous magnetic stirring. The solu-
tion was stirred until the reaction was seen to be
completed by IR spectroscopy. After 10 min, no start-
ing material remained. Solvent removal followed by
recrystallization (CH2Cl2–hexane at −20°C) afforded
0.30 g of orange–brown crystalline product (95%
yield). IR (THF, cm−1): wCO 1966 (vs), 1906 (s), 1801
2. Experimental
2.1. Reagents and general techniques
All manipulations were carried out by using standard
Schlenk vacuum-line and syringe techniques under an
atmosphere of oxygen-free Ar. All solvents for syn-
thetic use were reagent grade. Diethyl ether, hexane,
1,2-DME and tetrahydrofurane (THF) were dried and
distilled over sodium in the presence of benzophenone
under an Ar atmosphere. Methanol was stored over
1
(s), 1725 (CO2Me). H NMR (CD2Cl2, ppm) l: 7.68
(m, o-H, 8H, Ph); 7.60 (m, m-H, 8H, Ph); 7.46 (m, p-H,
4H, Ph); 5.61 (m, 1H, Fv); 5.47 (m, 2H, Fv); 5.14 (m,
1H, Fv); 5.02 (m, 1H, Fv); 4.30 (m, 1H, Fv); 3.60 (s,
3H, CO2CH3); 3.48 (s, 3H, CO2CH3); 3.33 (d, 2H,
ꢁCH2ꢁ); 1.67 (m, 2H, ꢁCH2ꢁ). 31P NMR (CD2Cl2,
ppm) d: 33.71 (s, 2P). Anal. Calc. for C45H36Mo2O9P2:
C, 55.44; H, 3.70. Found: C, 55.40; H, 3.66%.
,
molecular sieves (4 A) under Ar. The solvents were
bubbled with Ar for 1 h after distillation or degassed by
means of at least three freeze–pump–thaw cycles after
distillation and before use. Column chromatography
was performed by using Alfa neutral alumina at activity
II. Mo(CO)6, W(CO)6, Co2(CO)8, NaH, 1,2-bis-
(diphenylphosphino)ethane (dppe), I2, dimethylcarbon-
ate (CH3OꢁCOꢁOCH3), S2Ph2, Et2NH, DMSO,
Fe2(SO4)3(H2O)n, Na2SO4 anhydrous, Na2S2O3×5H2O,
KOH and glacial acetic acid (Fluka) and a solution 1.5
M of LiMe–LiBr in THF, PPh3, CuI, 1,4-dicloro-2-bu-
tyne (ClCH2CꢀCCH2Cl), TMSA (Me3SiCꢀCH) and a
solution 1 M of LiEt3BH in THF (Aldrich) were used
as received. Me3NO was sublimed prior to use and
stored under argon. The compounds [h5:h5-
(C5H3CO2Me)2]Mo2(CO)6 (1) [21], [(h5-C5H4CO2Me)-
2.3. Synthesis of [(p5-C5H4CO2Me)Mo(CO)2(dppe)]+
[(p5-C5H4CO2Me)Mo(CO)3]− (4)
To a solution of 0.35 g (0.6 mmol) of [(h5-
C5H4CO2Me)Mo(CO)3]2 (2) in THF (25 ml) was added
0.23 g (0.6 mmol) of dppe. The solution was stirred
until the reaction was seen to be completed by IR
spectroscopy (:2 h). The volatiles were removed by
vacuum and the residue, which was washed with hexane
and dried in vacuo, afforded 0.53 g of a brown solid
(90% yield). IR (THF, cm−1): wCO 1984 (vs), 1924 (m),
1
Mo(CO)3]2
(2)
[22],
Li2{[h5:h5-(C5H3CO2Me)2]-
1906 (s), 1784 (s), 1734 (CO2Me), 1713 (CO2Me). H
Mo2(CO)6} [21], Li2[(h5:h5-C10H8)W2(CO)6] [23], (h5-
C5H4CO2Me)Mo(CO)3I [22], [h5:h5-(C5H3CO2Me)2]-
Mo2(CO)6I2 [8c], and (h5-C5H5)Mo(CO)(dppe)(Cꢀ
CꢁCꢀCH) [24] were prepared according to literature
NMR (CDCl3, ppm) d: 7.70 (m, o-H, 8H, Ph); 7.45 (m,
m-H, 8H, Ph); 7.30 (m, p-H, 4H, Ph); 6.25 (t, JHP
=
2.50 Hz, 2H, Cp); 5.95 (t, JHP=2.50 Hz, 2H, Cp); 3.68
(s, 3H, CO2CH3); 3.31 (dd, 4H, ꢁCH2CH2ꢁ). 31P NMR
(CDCl3, ppm) l: 33.04 (s, 2P). Anal. Calc. for
C45H38Mo2O9P2: C, 55.33; H, 3.90. Found: C, 55.30; H,
3.85%.
procedures and were purified by TLC. The H-, 13C-,
1
and 31P-NMR spectra were recorded on a Bruker
AMX-300 and 500 instrument. Chemical shifts were

C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
141
2.4. Synthesis of trans-1,1%-[p5:p5-(C5H3CO2Me)2]-
Mo2(CO)4(PPh3)2I2 (5)
Anal. Calc. for C27H22IMoO4P: C, 48.80; H, 3.31.
Found: C, 48.72; H, 3.26%.
A
solution of trans-1,1%-[h5:h5-(C5H3CO2Me)2]-
2.6. Synthesis of cis-1,1%-[p5:p5-(C5H3CO2Me)2]-
Mo2(CO)4(v-SPh)2 (7)
Mo2(CO)6I2 (0.34 g, 0.40 mmol) and 0.21 g (0.80 mmol)
of PPh3 in 30 ml of THF was prepared. Me3NO (0.09
g, 0.80 mmol) was added with vigorous magnetic stir-
ring. After 10 min, no starting material remained; the
reddish–brown solid was extracted with CH2Cl2 and
purified by TLC using CH2Cl2–hexane (1:2) as eluent.
Solvent removal followed by recrystallization (CH2Cl2–
hexane, at −20°C) afforded red–brown crystalline
product (0.47 g, 90% yield). IR (THF, cm−1): wCO 1974
A solution of S2Ph2 (0.42 g, 1.91 mmol) in THF (20
ml) was added to a solution of Li2{trans-1,1%-[h5:h5-
(C5H3CO2Me)2]Mo2(CO)6} (0.95 mmol), prepared in
situ from LiEt3BH and cis-1,1%-[h5:h5-(C5H3CO2-
Me)2]Mo2(CO)6 (1), in the same solvent (40 ml). During
the addition period, the solution gradually changed
from yellow to brown. Progress of the reaction was
monitored periodically by infrared spectroscopy; after 5
min, a new band at 1858 cm−1 attributed to cis-1,1%-
[h5:h5-(C5H3CO2Me)2]Mo2(CO)4(m-SPh)2 (7) was ob-
served. After 2 h neither starting nor intermediate
materials remained. Upon filtration and removal of the
solvent under reduced pressure, a green–brown solid
was obtained which was washed with hexane (0.49 g,
68% yield). IR (THF, cm−1): wCO 1960 (vs), 1858 (vs),
1739 (CO2Me). 1H NMR (CDCl3, ppm) l: 7.51 (m,
o-H, 4H, Ph); 7.30 (m, m-H and p-Ph, 6H, Ph); 5.43
(m, 2H, Fv); 5.37 (m, 2H, Fv); 5.23 (m, 2H, Fv); 3.39
(s, 6H, CO2CH3). UV (THF): umax 416 nm. MS: m/e:
765.4 (M+), 713.3 (M+−2CO). Anal. Calc. for
C30H22Mo2O9S2: C, 27.91; H, 1.63. Found: C, 27.97; H,
1.67%.
1
(vs), 1897 (s), 1725 (CO2Me). H NMR (CDCl3, ppm)
l: 7.67–7.40 (m, all Ph); cis–cis (meso) isomer (27%) l:
6.47 (dd, 2H, Fv); 5.47 (dd, 2H, Fv); 4.75 (dd, 2H, Fv);
3.59 (s, 6H, CO2CH3); cis–cis (dl) isomer (34%) l: 6.41
(dd, 1H, Fv); 6.21 (dd, 1H, Fv); 6.10 (dd, 1H, Fv); 5.70
(dd, 1H, Fv); 5.15 (dd, 1H, Fv); 4.15 (dd, 1H, Fv); 3.64
(s, 3H, CO2CH3); 3.55 (s, 3H, CO2CH3); cis–trans
isomer (32%) l: 6.30 (dd, 1H, Fv); 5.56 (dd, 1H, Fv);
5.42 (dd, 1H, Fv); 5.02 (dd, 1H, Fv); 4.92 (dd, 1H, Fv);
4.86 (dd, 1H, Fv); 3.72 (s, 3H, CO2CH3); 3.66 (s, 3H,
CO2CH3); trans–trans isomer (7%) l: 5.31 (dd, 2H,
Fv); 4.80 (dd, 2H, Fv); 4.15 (dd, 2H, Fv); 3.79 (s, 6H,
CO2CH3). 31P NMR (CDCl3, ppm) cis–cis (meso) iso-
mer l: 43.68 (s, 2P); cis–cis (dl) isomer l: 43.36 (s, 1P);
43.11 (s, 1P); cis–trans isomer l: 44.37 (s, 1P); 62.94 (s,
1P); trans–trans isomer l: 62.78 (s, 2P). MS: m/e:
1049.0 (M+–2I–CO). Anal. Calc. for C54H42I2Mo2-
O8P2: C, 48.50; H, 3.14. Found: C, 48.57; H, 3.19%.
2.7. Synthesis of (p5:p5-C10H8)W2(CO)6(SPh)2 (8)
This compound was prepared as described above
using Li2[(h5:h5-C10H8)W2(CO)6] (0.21 g, 0.31 mmol)
and S2Ph2 (0.14 g, 0.62 mmol). After 3 h the solution
had changed from yellow to orange and the IR spec-
trum showed the total disappearance of the 1892 and
1800 cm−1 peaks corresponding to the lithium salt and
the appearance of two wCO bands at 2023 and 1937
cm−1 of the final product. Upon filtration and removal
of the solvent under reduced pressure, a dark orange
solid was obtained which was washed with hexane (0.22
g, 82% yield). IR (THF, cm−1): wCO 2023 (s), 1937 (vs).
1H NMR (acetone-d6, ppm) d: 7.52 (m, o-H, 4H, Ph);
7.37 (m, m-H, 4H, Ph); 7.30 (m, p-H, 2H, Ph); 6.40 (t,
4H, Fv); 5.87 (t, 4H, Fv). Anal. Calc. for
C28H18O6S2W2: C, 38.19; H, 2.05. Found: C, 38.14; H,
2.15%.
2.5. Synthesis of (p5-C5H4CO2Me)Mo(CO)2(PPh3)I (6)
The same procedure as described above was followed
in the preparation of this compound, using 1.77 g (2.07
mmol) of (h5-C5H4CO2Me)Mo(CO)3I, 0.54 g (2.07
mmol) of PPh3 and 0.23 g (2.07 mmol) of Me3NO.
After 10 min the solvent was removed under vacuum
and the product was purified by TLC using CH2Cl2–
hexane (1:2) as eluent. A red–brown residue was ob-
tained (0.89 g, 65% yield). IR (THF, cm−1): wCO 1975
1
(vs), 1899 (s), 1726 (CO2Me). H NMR (CDCl3, ppm)
l: 7.68–7.40 (m, all Ph); cis isomer (72%) l: 6.11 (ddd,
JHP=1.43, 1.43, 3.15 Hz, 1H, Cp); 5.56 (ddd, JHP=
1.43, 1.43, 3.15 Hz, 1H, Cp); 5.37 (ddd, JHP=1.43,
1.43, 3.15 Hz, 1H, Cp); 5.28 (ddd, JHP=1.43, 1.43, 3.15
Hz, 1H, Cp); 3.87 (s, 3H, CO2CH3); trans isomer (28%)
l: 5.42 (dt, JHP=2.36, 2.36, 2H, Cp); 4.83 (dt, JHP
=
2.8. Synthesis of [(p5-C5H4CO2Me)Mo(CO)(v-SPh)]2
(9)
2.36, 2.36 Hz, 2H, Cp); 3.72 (s, 3H, CO2CH3). 13C
NMR (CDCl3, ppm) l: 134.3–128.7 (Ph); cis isomer l:
102.8 (s, Ci, Cp); 96.2 (s, Co, Cp); 92.8 (s, Cm, Cp); 52.5
(s, Me, CO2Me); trans isomer l: 99.3 (s, Ci, Cp); 95.7
(s, Co, Cp); 89.9 (s, Cm, Cp); 52.4 (s, Me, CO2Me). 31P
NMR (CDCl3, ppm) cis isomer l: 43.15 (s, 1P); trans
isomer l: 62.78 (s, 1P). MS: m/e: 638.0 (M+−CO).
This complex was prepared in the same manner,
using Li[(h5-C5H4CO2Me)Mo(CO)3] (0.27 g, 0.87
mmol) and S2Ph2 (0.19 g, 0.87 mmol). The colour of the
solution immediately turned from yellow to dark red.
After 30 min neither starting nor intermediate materials

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C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
remained. Upon filtration and removal of the solvent
under reduce pressure a red–brown solid was obtained
which was washed with hexane (0.47 g, 76%). IR (THF,
C5H5)Mo(CO)(dppe)(CꢀCꢁCꢀCH) [24]. The colour of
the solution turned from reddish to dark orange. The
solvent was removed under vacuum and the dark or-
ange solid was purified by TLC using CH2Cl2–hexane
(2:1) as eluent (1.60 g, 78% yield). IR (THF, cm−1):
wCꢀC 2125 (vw), 2052 (w), wCO 1978 (s), 1903 (vs), 1854
1
cm−1): wCO 1926 (vs), 1833 (s). H NMR (acetone-d6,
ppm) l: 7.03 (m, o-H, 4H, Ph); 6.95 (m, m-H, 4H, Ph);
6.79 (m, p-H, 2H, Ph); cis isomer l: 5.45 (dd, JHS
=
1
2.15 Hz, 4H, Cp); 5.06 (m, 4H, Cp); 3.57 (s, 6H,
(vs); 1725 (CO2Me). H NMR (CDCl3, ppm) l: 7.50–
CO2CH3); trans isomer l: 5.06 (m, 2H, Cp); 4.98 (dd,
7.28 (m, all Ph); 4.51 (d, JHP=2.39 Hz, 5H, Cp); 3.04
(m, 2H, ꢁCH2ꢁ); 1.67 (m, 2H, ꢁCH2ꢁ); cis isomer (34%)
l: 6.11 (ddd, JHP=1.45, 1.45, 3.20 Hz, 1H, Cp%); 5.56
(ddd, JHP=1.45, 1.45, 3.20 Hz, 1H, Cp%); 5.37 (ddd,
JHS=2.30 Hz, 2H, Cp); 4.82 (m, 2H, Cp); 4.78 (m, 2H,
Cp); 3.55 (s, 6H, CO2CH3). UV (THF): umax 519, 342
nm. MS: m/e: 437.2 (M+−2CO−2SPh). Anal. Calc.
for C28H24Mo2O6S2: C, 47.20; H, 3.37. Found: C, 46.96;
H, 3.31%.
J
HP=1.45, 1.45, 3.20 Hz, 1H, Cp%); 5.28 (ddd, JHP=
1.45, 1.45, 3.20 Hz, 1H, Cp%); 3.87 (s, 3H, CO2CH3);
trans isomer (66%) l: 5.42 (dt, JHP=2.39, 2.39 Hz, 2H,
Cp%); 4.83 (dt, JHP=2.39, 2.39 Hz, 2H, Cp%); 3.76 (s,
3H, CO2CH3). 13C NMR (CDCl3, ppm) trans isomer l:
134.5–128.6 (Ph); 106.8 (s, ꢁCꢀCꢁCꢀCꢁ); 101.7 (s,
ꢁCꢀCꢁCꢀCꢁ); 99.3 (s, Cp); 95.6 (s, Ci, Cp%); 92.7 (s,
ꢁCꢀCꢁCꢀCꢁ); 89.9 (s, Co, Cp%); 87.6 (s, Cm, Cp%); 70.9
(s, ꢁCꢀCꢁCꢀCꢁ); 42.4 (s, Me, CO2Me). 31P NMR
(CDCl3, ppm) l: 93.29 (d, JPP=37.06 Hz, 1P, dppe);
61.94 (d, JPP=37.98 Hz, 1P, dppe); cis isomer l: 43.16
(s, 1P, PPh3); trans isomer l: 62.80 (s, 1P, PPh3). MS:
2.9. Synthesis of
(p5-C5H4CO2Me)Mo(CO)2(PPh3)(CꢀCꢁCꢀCH) (10)
A solution of complex 6 (1.24 g, 1.87 mmol) in THF
(10 ml) and Et2NH (25 ml) was treated at −80°C with
CuI (0.04 g, 0.217 mmol) and
a solution of
HCꢀCꢁCꢀCH (approximately 0.037 mol) in THF (25
ml) prepared in situ from ClCH2CꢀCCH2Cl and KOH
at −80°C [25]. The reaction mixture was gradually
warmed to room temperature (r.t.) and a change of
colour, from reddish to dark yellow, was observed. The
reaction was monitored by IR spectroscopy. Upon
removal of the solvent under reduced pressure, a brown
solid was obtained, and the product was extracted with
hexane (0.80 g, 73% yield). IR (THF, cm−1): wCꢀC 2158
(m), 2082 (w), 2054 (w); wCO 1978 (s), 1903 (vs), 1726
m/e:
1088.0
(M+−3CO).
Anal.
Calc.
for
C63H51Mo2O5P3: C, 64.51; H, 4.35. Found: C, 64.56; H,
4.39%.
2.11. Synthesis of [Co2{v-HC2CꢀC[Mo(CO)-
(dppe)(p5-C5H5)]}(CO)6] (12)
1
(CO2Me). H NMR (CDCl3, ppm) l: 7.68–7.46 (m, all
A solution of (h5-C5H5)Mo(CO)(dppe)(CꢀCꢁCꢀCH)
[24] (0.12 g, 0.19 mmol) in hexane (20 ml) was treated
with 0.06 g (0.19 mmol) of Co2(CO)8. After 3 h no
starting material remained. Upon removal of the sol-
vent under reduced pressure a reddish–brown solid was
obtained, and the product was extracted with hexane
and purified by TLC using hexane as eluent (0.13 g,
75% yield). IR (CDCl3, cm−1): wCꢀC 2105 (w), wCO 2082
Ph); cis isomer (45%) l: 6.11 (ddd, JHP=1.43, 1.43,
3.15 Hz, 1H, Cp); 5.56 (ddd, JHP=1.43, 1.43, 3.15 Hz,
1H, Cp); 5.37 (ddd, JHP=1.43, 1.43, 3.15 Hz, 1H, Cp);
5.28 (ddd, JHP=1.43, 1.43, 3.15 Hz, 1H, Cp); 3.87 (s,
3H, CO2CH3); 2.09 (s, 1H, ꢀCH); trans isomer (55%) l:
5.42 (dt, JHP=2.36, 2.36, 2H, Cp); 4.83 (dt, JHP=2.36,
2.36 Hz, 2H, Cp); 3.72 (s, 3H, CO2CH3); 2.04 (s, 1H,
ꢀCH). 13C NMR (CDCl3, ppm) trans isomer l: 188.7
(s, CO, CO2Me); 134.9–128.7 (Ph); 125.4 (s, Ca,
CꢀCꢁCꢀCH); 95.4 (s, Ci, Cp); 91.3 (s, Co, Cp); 85.3 (s,
Cm, Cp); 72.3 (s, Cb, CꢀCꢁCꢀCH); 70.9 (s, Cg,
CꢀCꢁCꢀCH); 60.9 (s, Cd, CꢀCꢁCꢀCH); 45.2 (s, Me,
CO2Me). 31P NMR (CDCl3, ppm) cis isomer l: 43.88
(s, 1P); trans isomer l: 63.52 (s, 1P). MS: m/e: 587.1
1
(m); 2059 (vs); 2040 (s), 2027 (sh), 1866 (s). H NMR
(CDCl3, ppm) l: 7.73–7.31 (m, all Ph); 6.22 (s, 1H,
ꢀCH); 4.51 (d, JHP=2.32 Hz, 5H, Cp); 2.96 (dd, 4H,
ꢁCH2CH2ꢁ). 31P NMR (CDCl3, ppm) l: 92.75 (d,
J
PP=38.58 Hz, 1P); 67.55 (d, JPP=38.62 Hz, 1P). MS:
m/e: 524.2 Anal. Calc. for
(M+−dppe).
C42H30Co2MoO7P2: C, 54.64; H, 3.25. Found: C, 54.60;
H, 3.20%.
(M+);
534.9
(M+−2CO).
Anal.
Calc.
for
C31H23MoO4P: C, 63.48; H, 3.92. Found: C, 63.54; H,
4.00%.
3. Results and discussion
2.10. Synthesis of Cp’(PPh3)(CO)2-
Mo–CꢀCꢁCꢀC–Mo(CO)(dppe)Cp (11)
3.1. Reactions of
[Cp%=(p5-C5H4CO2Me); Cp=(p5-C5H5)]
cis-1,1%-[p5:p5-(C5H3CO2Me)2]Mo2(CO)6 (1) and
[(p5-C5H4CO2Me)Mo(CO)3]2 (2) with dppe
A solution of complex 6 (1.16 g, 1.75 mmol) in THF
(10 ml) and Et2NH (25 ml) was treated with CuI (0.039
g, 0.204 mmol) and 1.11 g (1.75 mmol) of (h5-
The reactions of Cp2Mo2(CO)6 with PR3 may yield
phosphine-substituted
MoꢁMo
bonded
dimers

C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
143
Cp2Mo2(CO)6−x(PR3)x (x=1, 2) [26] or disproportion-
ation products [CpMo(CO)2(PR3)2]+ [CpMo(CO)3]−
[27,28] depending on reaction conditions and the elec-
tronic and steric properties of PR3. Disproportionation
is favoured over phosphine-substituted dimers when
electron-rich sterically undemanding and/or chelating
phosphines are used. The preparation of zwitterionic
fulvalene complexes are of interest in the context of
nonlinear optics [29–32]. The reaction of [h5:h5-
(C10H8)]Mo2(CO)6 with PPh3, Ph2PꢁCH2ꢁPPh2 or
Ph2PꢁCH2CH2ꢁPPh2 under thermal or photochemical
conditions gave no isolable products. Recently, it has
been shown that reactions of [h5:h5-(C5H3CO2Me)2]-
Mo2(CO)6 with PPhMe2, PPh2Me, P(n-Bu)3 or PMe3 in
the presence of 1 equiv. of Me3NO lead in high yield to
the formation of yellow–brown analytically pure prod-
ucts of composition [h5:h5-(C5H3CO2Me)2]Mo2(CO)5L2
[8c]. When we use P-donor ligands with cone angle
q]145° such as PPh3 or PCy3, the reactions gave no
isolable products. Following a similar procedure, the
reaction of [h5:h5-(C5H3CO2Me)2]Mo2(CO)6 (1) (cis
isomer) with dppe in THF solution in the presence of 1
equiv. of Me3NO lead to the formation of zwitterionic
ence of five fulvalene resonances in the 1H NMR
spectra shows that 3 is less symmetrical than its sub-
1
strates. Decoupling H–1H experiments show that only
the signal of the broad multiplet at 5.47 ppm is cou-
pled, so that it corresponds to two protons of the same
ring. This experiment made possible the assignment of
the two halves of the fulvalene systems. The signals at
5.61, 5.02 and 4.30 ppm are assigned to the cationic
fragment and the signals at 5.47 and 5.14 ppm to the
anionic half by analogy with the lithium salt previously
prepared [21]. For the compound 4, only two signals at
6.25 and 5.95 ppm attributed to the cationic fragment
are observed. The signals due to the anionic half could
not be observed; the same happened in analogous com-
pounds [33]. The 31P NMR spectra shows a single
signal for both compounds at ca. 33.04 ppm in the
characteristic range of the cis isomer [9b,35]. The zwit-
terionic character is also demostrated by the reaction
between the anionic half of 3 and 4 with an electrophile
as MeI to yield the methyl salts {trans-1,1%-[h5:h5-
(C5H3CO2Me)2]Mo2(CO)5(dppe)(Me)}I
C5H4CO2Me)Mo(CO)3(Me)] in
and
addition
[(h5-
to
[(h5-C5H4CO2Me)Mo(CO)2(dppe)]+I− respectively, the
salts could not be isolated, but were characterized by
their IR spectra. During the reaction, the disappearance
of the two bands due to the anionic half and the
appearance of two new bands (2022, 1939 cm−1) at-
tributed to the methylated fragment is observed. The
IR wCO data for the reaction product shown that the
CO stretching frequencies for the unreacted cationic
half remained virtually unchanged.
product
of
composition
trans-1,1%-[h5:h5-
(C5H3CO2Me)2]Mo2(CO)5(dppe) (3). This reaction does
not take place thermally unless Me3NO is present. The
reaction of [(h5-C5H4CO2Me)Mo(CO)3]2 (2) with dppe
leads to the formation of the disproportionation com-
pound
[(h5-C5H4CO2Me)Mo(CO)2(dppe)]+
[(h5-
C5H4CO2Me)Mo(CO)3]− (4), and in this case, the
presence of Me3NO is not necessary. This different
behaviour observed can be due to a stronger MoꢁCO
bond in the fulvalene complex 1 than cyclopentadienyl
analogous compound 2. Both compounds are partially
soluble in THF, CH2Cl2 and acetonitrile. IR monitor-
ing of these reactions shows the formation of one
isosbestic point at 2010 cm−1 which is indicative of a
clean reaction without the formation of detectable in-
termediates and secondary products. The IR spectra of
3 and 4 show bands at 1906 (s), 1801 (s) cm−1 and 1906
(s), 1784 (s) cm−1, respectively, due to the anionic
fragment, and are very similar to those shown by the
lithium salts Li2{trans-1,1%-[h5:h5-(C5H3CO2Me)2]-
Mo2(CO)6} [21] and Li[(h5-C5H4CO2Me)Mo(CO)3] [22]
previously prepared. Bands at 1966 (vs) (3) and 1984
(vs), 1924 (m) (4) cm−1, respectively, are assigned to
the cationic fragment, by analogy to [CpMo(CO)2L2]+
(2000–1990 and 1920–1900 cm−1) [9a,26a,33]. For the
compound 3 another band at ca. 1915 cm−1, should be
observed and is overlapped by the strong band at 1906
cm−1 of the anionic fragment. The intensity ratios are
consistent with the cis geometry [34] (high-energy band
more intense). Only cis isomers are also observed for
the FvMo2(CO)4L2X2 (L=PPh3, PCy3, PXy3; X=Cl,
Br) [9b] and [h5:h5-(C5H3CO2Me)2]Mo2(CO)5L2 (L=
PPh2Me, PPhMe2, P(n-Bu)3) [8c] compounds. The pres-
3.2. Cyclopentadienyl and ful6alene thiolate complexes
The reaction of Li[(h5-C5H4CO2Me)Mo(CO)3] [22]
with S2Ph2 in THF solution leads to the formation of
brown compound [(h5-C5H4CO2Me)Mo(CO)(m-SPh)]2
(9). This method involves nucleophilic displacement of
the group –SPh in S2Ph2 using the anionic complex as
nucleophile. The reaction was monitored by IR spec-
troscopy and when the reactants were mixed, carbonyl
stretching frequencies due to starting material disap-
peared and four bands at 2029, 1976, 1944 and 1868
cm−1 were observed. The first and third absorptions
correspond closely to values reported for monomeric
(h5-C5H5)M(CO)3(SR) (M=Mo, W) species [10] and
indicate the presence of (h5-C5H4CO2Me)Mo-
(CO)3(SPh). The other two bands closely resemble
those of [(h5-C5H5)M(CO)2(m-SR)]2 species (M=Mo,
W) [10] and are assigned to the dimeric [(h5-
C5H4CO2Me)Mo(CO)2(m-SPh)]2
compound.
After
about 30 min these bands disappeared and two new
bands at 1926 and 1833 cm−1 were observed in the
charactheristic range of [(h5-C5H5)M(CO)(m-SR)]2
(M=Mo, W) species [10b], which are assigned to the
dimeric compound 9 with a formal double bond

144
C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
MoꢁMo (Scheme 1). The presence of two wCO bands
pound, leads to the dimeric [(h5-C5H5)Mo(CO)2-
(m-SPh)]2 specie [10a]. This can be due to negative
inductive and mesomer effects of –CO2Me group in the
cyclopentadienyl ring, which lead to a faster reaction
rate. The reactions of fulvalene complexes Li2{trans-
may indicate that the compound can exist as a mixture
1
of cis and trans isomers. In fact, the H NMR spectrum
shows six signals, because of the presence of non-equiv-
alent Cp% ligands in the trans isomer, those at 5.45 and
5.06 ppm are attributed to eight protons of two cy-
clopentadienyl rings for the cis isomer and those at
5.06, 4.98, 4.82 and 4.78 ppm are due to eight protons
of two cyclopentadienyl rings for the trans isomer. Two
singlets at 3.57 and 3.55 ppm also appear, correspond-
ing to the methyl protons of ꢁCO2Me groups in both
isomers. The UV spectrum shows bands at 519 and 342
nm, which are attributed to the dp“s* and s“s*
transitions, respectively. The last transition can be asso-
ciated with the metal–metal bond [36]. The higher
decarbonylation observed with respect the unsubsti-
tuted cyclopentadienyl PPN[(h5-C5H5)Mo(CO)3] com-
1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)6}
[21]
Li2[(h5:h5-C10H8)W2(CO)6] [23] with S2Ph2 produce the
cis-1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)4(m-SPh)2
(7)
and
and (h5:h5-C10H8)W2(CO)6(SPh)2 (8) compounds re-
spectively (Scheme 1). For the molybdenum fulvalene
complex, IR monitoring shows at the begining of the
reaction two wCO bands at 2032 and 1951 cm−1 due to
the formation of the trans-1,1%-[h5:h5-(C5H3CO2Me)2]-
Mo2(CO)6(SPh)2 compound. At the end of the reaction,
only two new bands at 1960 and 1858 cm−1 are ob-
served, and are attributed to the compound 7. For the
tungstene fulvalene complex, IR monitoring only shows
Scheme 1.

C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
145
two new bands at 2023 and 1937 cm−1 in the charac-
teristic range of (h5-C5H5)M(CO)3(SR) (M=Mo, W)
complexes [10b] and the dark orange solid isolated was
similar behaviour is observed in cyclopentadienyl com-
plexes [10a].
1
identified as 8. The H NMR spectrum for 7 presents
3.3. Cyclopentadienyl and ful6alene butadiynyl
three multiplets at 5.43, 5.37 and 5.23 ppm due to six
protons of the fulvalene ring, and a singlet at 3.39 ppm
assigned to the methyl protons of the ꢁCO2Me group. 8
shows two triplets at 6.40 and 5.87 ppm due to eight
protons of the fulvalene ring; these values are similar to
(h5:h5-C10H8)W(CO)6I2 compound [23] whose X-ray
structure was determined and consists of two W(CO)3I
units which are at opposite sides of the fulvalene ligand
[8a]. The different degree of decarbonylation observed
between the cyclopentadienyl (9) and fulvalene (7)
molybdenum complexes can be due to the difficulty in 7
to yield a double MꢂM bond, which would lead to the
bending away from the planarity of the rings. The
minor degree of decarbonylation of 8 with respect to 7
indicates the higher stability of thiolate tungsten species
as compared to analogous molybdenum compounds. A
complexes
The reaction of (h5-C5H4CO2Me)Mo(CO)3I [22] with
PPh3 in the presence of 1 equiv. of Me3NO gives the
monosubstituted
derivative
(h5-C5H4CO2Me)Mo-
(CO)3(PPh3)I (6) in high yield as a mixture of cis and
trans isomers (Scheme 2). The identity of the isomers
was proven according to well-established IR and NMR
criteria [34,35,37]. The 1H-NMR spectrum shows six
signals due to protons of the carbometoxycyclopentadi-
enyl ring. According to l values, integrals and bidimen-
sional spectroscopy COSY (Fig. 1), the double doublet
of doublets signals at 6.11, 5.56, 5.37 and 5.28 ppm
(JHP=1.43, 1.43 and 3.15 Hz, respectively) are assigned
to the cis isomer while the doublet of triplets signals at
5.42 and 4.83 ppm (JHP=2.36 and 2.36 Hz, respec-
Fig. 1. COSY experiment for 6 in CDCl3.

146
C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
Scheme 2.

C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
147
Scheme 3.
tively) are due to the trans isomer. The 31P NMR
spectrum exhibits two singlets at 43.15 (cis) and 62.78
ppm (trans). The ratio of cis:trans isomers obtained
from the integrals of these resonances (72:28) agreed
reasonably well with that obtained from 1H NMR data.
The IR spectrum in THF exhibits two absorption
bands at 1975 (vs) and 1899 (s) cm−1 associated with
terminal wCO modes. The higher frequency (sym) which
is more intense than the lower one (antisym), supports
the isomers ratio made from the 1H and 31P NMR data.
The air-unstable yellow diynyl complex (h5-C5H4-
CO2Me)Mo(CO)3(PPh3)(CꢀCꢁCꢀCH) (10) was ob-

148
C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
tained from the CuI-catalyzed reaction between 6 and
buta-1,3-diyne [25] in the presence of diethylamine and
THF, which serves both to generate the active diynyl-
copper intermediate and to remove HCl as diethylam-
monium chloride (Scheme 2). The complex is
characterized from its spectral properties and mass
absorptions at 1978 (s), 1903 (vs) and 1854 (vs) cm−1
and two weak wCꢀC bands at 2125 and 2052 cm−1. The
1H NMR spectrum shows the signals due to Cp and
Cp% proton rings for both isomers and in the 31P NMR
spectrum at approximately 93 and 62 ppm two doblet
signals are observed which are consistent with a cis
arrangement of the dppe ligand. At approximately 43
(cis) and 62 (trans) ppm, the PPh3 ligand signal ap-
pears. The 13C NMR data exhibits four resonances of
the ꢁC4ꢁ chain at 106.8, 101.7, 92.7 and 70.9 ppm.
1
spectrum. The H NMR spectrum shows the same six
signals due to protons of the carbometoxycyclopentadi-
enyl ring, and two new singlets resonances at 2.09 and
2.04 ppm assigned to the terminal ꢀCH of the cis and
trans isomers, respectively. Two signals at 43.88 (cis)
and 63.52 (trans) ppm appear in the 31P NMR spec-
Reaction
between
(h5-C5H5)Mo(CO)(dppe)-
(CꢀCꢁCꢀCH) [24] and Co2(CO)8 in hexane resulted in
the mixed complex [Co2{m-HC2CꢀC[Mo(CO)(dppe)(h5-
C5H5)]}(CO)6] (12) (Scheme 2). The wCO spectrum con-
tained four absorptions; the characteristic pattern of a
coordinated Co2(CO)6 unit (three bands) and a wCO at
1866 cm−1 due to the Mo fragment, which upon substi-
tution was increased (1847 cm−1 in the parent com-
plex). For the preparation of butadiynyl fulvalene
analogous complex, we previously isolated in high yield
the trans-1,1%-[h5:h5-(C5H3CO2Me)2]Mo2(CO)4(PPh3)2I2
(5) by reaction between the trans-1,1%-[h5:h5-
(C5H3CO2Me)2]Mo2(CO)6I2 and PPh3 in THF in the
presence of 2 equiv. of Me3NO (Scheme 3). The com-
pound 5 may exist as four different geometrical isomers
(not including enantiomers), trans–trans, cis–trans,
cis–cis (meso) and cis–cis (dl) (Fig. 2). Two CO
stretching vibrations at 1974 (vs) and 1897 (s) are
observed. The intensity ratio is consistent with the basic
cis geometry (the more intense the higher frequency).
The 1H NMR data for this complex is listed in the
experimental section. The spectrum has been assigned
on the basis of chemical shift, integrals, spin–spin
coupling information, and two-dimensional homonu-
clear correlation spectroscopy (COSY and NOESY)
1
trum. The ratio of both isomers obtained from H and
31P NMR data is 45:55. Using the same methodology,
the homobimetallic ꢁC4ꢁ (h5-C5H4CO2Me)(PPh3)-
(CO)2Moꢁ(CꢀCꢁCꢀC)ꢁMo(CO)(dppe)(h5-C5H5)
(11)
complex was obtained by reaction between 6 and (h5-
C5H5)Mo(CO)(dppe)(CꢀCꢁCꢀCH) [24] as a mixture of
cis and trans isomers with respect to the PPh3 ligand
(Scheme 2). The IR spectrum in THF exhibits three wCO
1
[38]. The H NMR spectrum can give rise to 18 signals
due to fulvalene proton rings (three for each trans–
trans and cis–cis (meso) isomers and six for each
cis–trans and cis–cis (dl) isomers) (Fig. 2). The trans
half of cis–trans-5 is diastereotopic due to its chiral cis
half and apparently is the only species in this system
which exhibits a full ABX resonance pattern. The fulva-
lene region of the spectrum displays the expected sig-
nals relatively well resolved. According to COSY
spectrum, including the normal (1D) spectrum for com-
parison of the diagonal connectivities, the protons cor-
responding to each of the fulvalene rings can be
distinguished and assigned unambigously (Section 2).
The ratio of trans–trans, cis–trans, cis–cis (meso) and
cis–cis (dl) was found to be 7:32:27:34 on the basis of
integrals. The 31P NMR spectrum exhibits six reso-
nances at l 62.7 (trans–trans), 62.9 (cis–trans), 44.4
(cis–trans), 43.7 (cis–cis (meso)), 43.3 and 43.1 (cis–cis
(dl)), respectively. The cis:trans ratios found for the
fulvalene dimolybdenum complex is similar to that for
cyclopentadienyldimolybdenum analogous compound.
Fig. 2. Schematic representation of the four different stereoisomers of
5.

C. Moreno et al. / Inorganica Chimica Acta 312 (2001) 139–150
149
Bruce, P.J. Low, K. Costuas, J.F. Halet, S.P. Best, G.A. Heath,
J. Am. Chem. Soc. 122 (2000) 1949.
The reaction of 5 with buta-1,3-diyne was carried out
under similar conditions to those for the cyclopentadi-
enyl analogous compound. A very air-unstable yellow
solid was extracted with hexane but could not be
characterized. The higher unstability for the butadiynyl
fulvalene complex with respect to the butadiynyl cy-
clopentadienyl analogous compound 10 was observed.
[13] (a) W. Weng, T. Bartik, M. Brady, B. Bartik, J.A. Ramsden,
A.M. Arif, J.A. Gladysz, J. Am. Chem. Soc. 117 (1995) 11922.
(b) T. Bartik, B. Bartik, M. Brady, R. Dembinski, J.A. Gladysz,
Angew. Chem., Int. Ed. Engl. 35 (1996) 414. (c) B. Bartik, R.
Dembiski, T. Bartik, A.M. Arif, J.A. Gladysz, New J. Chem. 21
(1997) 739. (d) M. Brady, W. Weng, Y. Zhou, J.W. Seyler, A.J.
Amoroso, A.M. Arif, M. Bo¨hme, G. Frenking, J.A. Gladysz, J.
Am. Chem. Soc. 119 (1997) 775.
[14] (a) N. Le Narvor, L. Toupet, C. Lapinte, J. Am. Chem. Soc. 117
(1995) 7129. (b) F. Coat, M.A. Guillevic, L. Toupet, F. Paul, C.
Lapinte, Organometallics 16 (1997) 5988. (c) M.I. Bruce, L.I.
Denisovich, P.J. Low, S.M. Peregudova, N.A. Ustynyunk,
Mendeleev Commun. (1996) 200. (d) M.I. Bruce, M. Ke, P.J.
Low, J. Chem. Soc., Chem. Commun. (1996) 2405. (e) B.E.
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Acknowledgements
We express our great appreciation to the Direccio´n
General de Ensen˜anza Superior e Investigacio´n Cien-
t´ıfica (Grant no. PB 97/0036), Spain.
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