Synthesis, characterization, and electrochemical properties of organotransition metal fullerene derivatives containing dppf ligands. Crystal structures of fac-Mo(CO)3(dppf)(CH3CN), W(CO)4(dppf), and mer-W(CO)3(dppf)(η2-C60)

Article abstract of DOI:10.1021/om000579+

Reaction of Mo(CO)₃(CH₃CN)₃ with an equimolar amount of 1,1′-bis(diphenylphosphino)-ferrocene (dppf) in refluxing acetonitrile gives rise to fac-Mo(CO)₃(dppf)(CH₃CN) (1) in 51% yield. While 1 reacts with [60]fullerene in chlorobenzene at about 90°C to produce an isomeric mixture of fac/mer-Mo(CO)₃(dppf)(η²-C₆₀) (2) in 21% yield, the photolysis of Mo(CO)₄(dppf) and [60]fullerene in chlorobenzene at ambient temperature affords 2 in 87% yield. Similarly, mer-W(CO)₃(dppf)(η²-C₆₀) (3), [mer-W(CO)₃(dppf)]₂(η²,η²-C₆₀) (4), mer-W(CO)₃(dppf) (η²-C₇₀) (5), and [mer-W(CO)₃ (dppf)]₂(η²,η²-C₇₀) (6) can be prepared by photolysis of W(CO)₄(dppf) with [60]- or [70]fullerene in 87%, 13%, 51%, and 48% yields, respectively. While all the new compounds 1-6 have been characterized by elemental analyses and spectroscopic techniques, the structures of 1, W(CO)₄(dppf), and 3 have been confirmed by single-crystal X-ray diffraction analyses. The cyclic voltammetric responses of 2 and 3 show that their sequential fullerene-centered reductions are shifted toward more negative potential values by about 0.2 V with respect to those of free C₆₀. Such a negative shift is quite similar to that previously observed for the related complexes W(CO)₃(dppb)(η²-C₆₀) and Mo(CO)₃(dppe)(η²-C₆₀). Moreover, the fullerene-centered reductions of 5 are negatively shifted by about 0.1 V with respect to free C₇₀, thus supporting that the η²-coordination of the W(CO)₃(dppf) fragment to fullerenes causes a higher electronic interaction with C₆₀ than with C₇₀.

Full text of DOI:10.1021/om000579+

5342
Organometallics 2000, 19, 5342-5351
Syn th esis, Ch a r a cter iza tion , a n d Electr och em ica l
P r op er ties of Or ga n otr a n sition Meta l F u ller en e
Der iva tives Con ta in in g d p p f Liga n d s. Cr ysta l Str u ctu r es
of fa c-Mo(CO)3(d p p f)(CH3CN), W(CO)4(d p p f), a n d
m er -W(CO)3(d p p f)(η2-C60)
Li-Cheng Song,*,† J in-Ting Liu,† Qing-Mei Hu,† Guan-Feng Wang,†
Piero Zanello,‡ and Marco Fontani‡
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai
University, Tianjin 300071, China, and Dipartimento di Chimica dell’Universita` di Siena,
Via Aldo Moro, I-53100 Siena, Italy
Received J uly 5, 2000
Reaction of Mo(CO)3(CH3CN)3 with an equimolar amount of 1,1′-bis(diphenylphosphino)-
ferrocene (dppf) in refluxing acetonitrile gives rise to fac-Mo(CO)3(dppf)(CH3CN) (1) in 51%
yield. While 1 reacts with [60]fullerene in chlorobenzene at about 90 °C to produce an isomeric
mixture of fac/ mer-Mo(CO)3 (dppf)(η2-C60) (2) in 21% yield, the photolysis of Mo(CO)4(dppf)
and [60]fullerene in chlorobenzene at ambient temperature affords 2 in 87% yield. Similarly,
mer-W(CO)3(dppf)(η2-C60) (3), [mer-W(CO)3(dppf)]2(η2,η2-C60) (4), mer-W(CO)3(dppf) (η2-C70)
(5), and [mer-W(CO)3 (dppf)]2(η2,η2-C70) (6) can be prepared by photolysis of W(CO)4(dppf)
with [60]- or [70]fullerene in 87%, 13%, 51%, and 48% yields, respectively. While all the
new compounds 1-6 have been characterized by elemental analyses and spectroscopic
techniques, the structures of 1, W(CO)4(dppf), and 3 have been confirmed by single-crystal
X-ray diffraction analyses. The cyclic voltammetric responses of 2 and 3 show that their
sequential fullerene-centered reductions are shifted toward more negative potential values
by about 0.2 V with respect to those of free C60. Such a negative shift is quite similar to that
previously observed for the related complexes W(CO)3(dppb)(η2-C60) and Mo(CO)3(dppe)(η2-
C60). Moreover, the fullerene-centered reductions of 5 are negatively shifted by about 0.1 V
with respect to free C70, thus supporting that the η2-coordination of the W(CO)3(dppf)
fragment to fullerenes causes a higher electronic interaction with C60 than with C70.
In tr od u ction
corresponding heteronuclear transition metal M/Fe (M
) Mo, W) fullerene complexes could be prepared.
Fortunately, we have obtained such expected complexes
from these reactions, namely, fac/ mer-Mo(CO)3(dppf)-
(η2-C60), mer-W(CO)3(dppf)(η2-C60), [mer-W(CO)3(dppf)]2-
(η2,η2-C60), mer-W(CO)3(dppf)(η2-C70), and [mer-W(CO)3
(dppf)]2(η2,η2-C70). It is worth noting that such hetero-
nuclear transition metal C60 derivatives are rare,6e and
up to now no C70 heteronuclear transition metal deriva-
tives, to our knowledge, have appeared in the literature.
Herein we report the synthesis, spectroscopic charac-
terization, and electrochemistry of these new C60 and
C70 heteronuclear transition metal derivatives, as well
as the crystal structures of two starting materials and
one of the fullerene derivatives.
Since the first preparation of organotransition metal
fullerene complexes,1 the organometallic chemistry of
[60]- and [70]fullerenes has been receiving great atten-
tion.2 Conceivably [60]- and [70]fullerenes can form
organometallic complexes with single, double, triple, or
multiple metal centers in a variety of coordination
modes from η1 to η6. In fact, some of these types of
transition metal fullerene complexes have been already
prepared and structurally characterized.3-6 We are
interested in the synthesis, characterization, and prop-
erties of organotransition metal fullerene derivatives.7
As a continuation of our project related to the chemistry
of transition metal fullerene complexes, we recently
initiated studies on the thermal reaction of fac-Mo(CO)3-
(dppf)(CH3CN) with C60 and photolysis of Mo(CO)4(dppf)
with C60 and W(CO)4(dppf) with C60 or C70 to see if the
Resu lts a n d Discu ssion
Syn th esis, Sp ectr oscop ic Ch a r a cter iza tion , a n d
Cr ysta l Str u ctu r e of fa c-Mo(CO)3 (d p p f)(CH3CN)
(1). Treatment of Mo(CO)3(CH3CN)3 with an equimolar
quantity of 1,1′-bis(diphenylphosphino)ferrocene (dppf)
in boiling acetonitrile for 30 h resulted in formation of
1 in 51% yield, as shown in eq 1.
* To whom correspondence should be addressed. Fax: 0086-22-
23504853. E-mail: lcsong@public.tpt.tj.cn.
† Nankai University.
‡ Universita` di Siena.
(1) Fagan, P. J .; Calabrese, J . C.; Malone, B. Science 1991, 252, 1160.
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Compound 1 is an air-sensitive, golden solid, which
might exist as another isomeric form, namely, the mer
10.1021/om000579+ CCC: $19.00 © 2000 American Chemical Society
Publication on Web 11/10/2000

Organotransition Metal Fullerene Derivatives
Organometallics, Vol. 19, No. 25, 2000 5343
was formed. Further treatment of this resulting solution
by column chromatography afforded 2 in 21% yield.
However, when an equimolar mixture of Mo(CO)4(dppf)
and C60 in chlorobenzene was irradiated with a UV 450
W photochemical lamp at room temperature for 2 h,
compound 2 was obtained in a much higher yield (87%),
as shown in eq 2.
isomer. However, the X-ray diffraction analysis has
shown that it is actually the fac isomer. The molecular
ORTEP diagram of 1 is shown in Figure 1, whereas
Table 1 lists its selected bond lengths and angles. As
seen in Figure 1, compound 1 contains one CH3CN
ligand bonded to Mo via its N atom and cis to both of
the phosphorus atoms P(1) and P(2) of the dppf ligand.
That is, 1 adopts the fac configuration. The dppf ligand
is chelated to the Mo atom with a bite angle of 97.800-
(19)°. This bite angle is very close to corresponding bite
angles of fac-W(CO)3(dppf)(CH3CN) (98.05(6)°)8 and Mo-
(CO)4(dppf) (95.28(2)°).9 The two cyclopentadienyl rings
in the dppf ligand are almost parallel with a dihedral
angle of 2.37(0.09)° and staggered to each other. While
the IR spectrum of 1 shows three absorption bands in
the region 1808-1926 cm-1 for its terminal carbonyls,10
Compound 2 is an air-sensitive, dark green solid,
which slightly dissolves in polar solvents such as
chloroform, toluene, THF, carbon disulfide, and chlo-
robenzene, but does not dissolve in nonpolar solvents
such as hexane and petroleum ethers. Obviously, this
C60 derivative, just like its precursor 1, might exist as
a fac isomer, a mer isomer, or as a mixture of the fac
and mer isomers. In fact, the 31P NMR spectrum of 2
indicated that it exists as an isomeric mixture of the
fac and mer isomers. This is because that the 31P NMR
spectrum of 2 (Figure 2) shows two doublets at 39.31
and 29.86 ppm assignable to the two different P atoms
in the mer isomer and a singlet at 33.56 ppm assignable
to the two identical P atoms of the fac isomer. The IR
spectrum of 2 displays four bands in the range 1434-
526 cm-1 for its C60 core12 and five bands in the region
2000-1882 cm-1 for its terminal carbonyls.10 The latter
is in good agreement with 2 being a mixture of the two
isomers, since the number of IR active bands cannot
exceed but may be less than the number of CO ligands
in the complex.13
1
the H NMR spectrum of 1 exhibits a multiplet around
7.40 ppm assigned to its phenyl groups and a singlet at
1.98 ppm to its methyl group. In addition, the 31P NMR
spectrum of 1 displays only one singlet at 37.86 ppm,
which is consistent with its fac configuration, cofirmed
by single-crystal X-ray diffraction analysis. This is
because the fac isomer has two magnetically identical
P atoms, whereas the mer isomer has two magnetically
different P atoms.11
Syn th esis a n d Sp ectr oscop ic Ch a r a cter iza tion
of fa c/m er -Mo(CO)3(d p p f)(η2-C60) (2). When an equi-
molar quantity of 1 was added to a solution of C60 in
chlorobenzene followed by stirring and heating the
mixture at about 90 °C for 2 h, a dark green solution
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Song, Y.-L.; Fang, G.-Y.; Wang, Y.-X.; Liu, C.-F.; Song, L.-C.; Zhu, Y.-
H.; Hu, Q.-M. Appl. Phys. Lett. 1999, 74, 1. (d) Song, L.-C.; Zhu, Y.-H.;
Hu, Q.-M. J . Chem. Res., Synop. 1999, 56. (e) Song, L.-C.; Liu, J .-T.;
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Principles and Applications of Organotransition Metal Chemistry, 2nd
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(5) For trinuclear fullerene derivatives, see: (a) Hsu, H.-F.; Shapley,
J . R. J . Am. Chem. Soc. 1996, 118, 9192. (b) Hsu, H.-F.; Shapley, J . R.
J . Chem. Soc., Chem. Coommun. 1997, 1125. (c) Park, J . T.; Song, H.;
Cho, J .-J .; Chung, M.-K.; Lee, J .-H.; Suh, I.-H. Organometallics 1998,
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1998, 17, 4477.

5344 Organometallics, Vol. 19, No. 25, 2000
Song et al.
F igu r e 1. ORTEP diagram of 1 with ellipsoids drawn at 30% probability.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 1
Mo(1)-C(3)
Mo(1)-C(2)
Mo(1)-C(1)
Mo(1)-N(1)
Mo(1)-P(2)
1.946(3)
1.962(3)
1.967(3)
2.222(2)
2.5702(6)
Mo(1)-P(1)
Fe(1)-C(16)
Fe(1)-C(18)
P(1)-C(11)
P(2)-C(16)
2.5985(6)
2.026(2)
2.067(2)
1.821(2)
1.812(2)
C(3)-Mo(1)-C(2)
C(3)-Mo(1)-C(1)
C(2)-Mo(1)-C(1)
87.18(10) C(1)-Mo(1)-P(2) 173.22(8)
83.94(10) N(1)-Mo(1)-P(2)
84.63(11) C(3)-Mo(1)-P(1)
85.53(5)
97.92(7)
C(3)-Mo(1)-N(1) 177.67(9)
C(2)-Mo(1)-P(1) 170.84(8)
C(2)-Mo(1)-N(1)
C(1)-Mo(1)-N(1)
C(3)-Mo(1)-P(2)
C(2)-Mo(1)-P(2)
93.67(9)
98.30(9)
92.31(7)
89.56(8)
C(1)-Mo(1)-P(1)
N(1)-Mo(1)-P(1)
P(2)-Mo(1)-P(1)
88.33(8)
81.53(5)
97.800(19)
In the UV-vis spectrum of 2, those intense bands
between 200 and 400 nm are close to those of free C60.
This is typical of a [60]fullerene cage which has been
modified by complexation.14 The biggest changes in the
spectrum of 2 compared with that of free C60 appear in
the visible range. A new band appearing at 436.3 nm
might be the reason for the color change of the reaction
mixture from purple C60 to dark green 2 and suggests
that the [60]fullerene is coordinated to molybdenum in
an η2-fashion in the compound.3i,7e,15 In addition, the 1H
NMR spectrum of 2 indicates the presence of corre-
sponding phenyl and substituted cyclopentadienyl groups.
Syn th esis a n d Sp ectr oscop ic Ch a r a cter iza tion
of m er -W(CO)3(d p p f)(η2-C60) (3) a n d [m er -W(CO)3-
(d p p f)]2(η2,η2-C60) (4). Irradiation of an equimolar
mixture of W(CO)4 (dppf) and C60 in chlorobenzene with
a UV 450 W photochemical lamp at room temperature
for 2 h gave rise to a dark green solution. Further
treatment of this solution by TLC afforded 3 in 87%
yield and 4 in 13% yield, as shown in eq 3.
F igu r e 2. 31P NMR spectrum of 2.
not soluble in nonpolar solvents such as hexane and
petroleum ethers. 3 and 4 have been characterized by
elemental analysis, spectroscopic methods, and particu-
larly for 3 X-ray diffraction. The 31P NMR spectra
indicated that they all have a meridional geometry,
since the 31P NMR spectrum of 3 shows two doublets
at 18.47 and 12.79 ppm, and that of 4 exhibits two
singlets at 23.67 and 16.94 ppm. This implies that they
all contain two different P atoms and belong to the mer
isomers. The IR spectra of 3 and 4 display four bands
in the range 1434-514 cm-1 for their C60 cores12 and
three bands in the region 1998-1868 cm-1 for their
terminal carbonyls.10 The latter is in good agreement
with the fact that 3 and 4 are single isomers, since the
isomeric mixtures would have more IR active bands for
Compounds 3 and 4 are air-stable solids, which are,
similar to 2, slightly soluble in those polar solvents, but
(14) (a) Taylor, R.; Hare, J . P.; Abdul-Sada, A. K.; Kroto, H. W. J .
Chem. Soc., Chem. Commun. 1990, 1423. (b) Hare, J . P.; Kroto, H.
W.; Taylor, R. Chem. Phys. Lett. 1991, 177, 394. (c) Akasaka, T.; Ando,
W.; Kobagashi, K.; Nagase, S. J . Am. Chem. Soc. 1993, 115, 1605.
(15) Hirsch, A.; Gro¨sser, T.; Skiebe, A.; Soi, A. Chem. Ber. 1993,
126, 1061.

Organotransition Metal Fullerene Derivatives
Organometallics, Vol. 19, No. 25, 2000 5345
Compounds 5 and 6 are air-stable solids, which are,
similar to 3 and 4, slightly soluble in those polar
solvents, but not soluble in the nonpolar solvents. These
two [70]fullerene derivatives are single mer isomers,
which have been characterized by elemental analysis,
IR, 1H NMR, 31P NMR, and UV-vis spectroscopies. The
31P NMR spectra of 5 and 6 each show two broader
singlets centered at 16.65/10.20 ppm and at 12.27/5.54
ppm, each singlet being surrounded by satellite peaks
due to coupling between P atoms and tungsten isotopes,
such as isotope 183W. This indicates that there are two
different P atoms present in each of 5 and 6; thus they
are all mer isomers.
The IR spectra of 5 and 6 display several bands in
the range 1636-535 cm-1 for their C70 cores12 and three
bands in the region 1999-1870 cm-1 for their terminal
carbonyls.10 This is also in good agreement with 5 and
6 being mer isomers. In the UV-vis spectra of 5 and 6
the intense bands between 200 and 400 nm are close to
those of free C70.14 A new band appearing at ca. 457 nm
instead of the band at 470 nm for free C70 might be
attributed to the [70]fullerene being coordinated to the
metal in an η2-fashion.3i,7e,15
Since C70 has four nonequivalent reactive 6:6 bonds,
its double addition would be very complicated. However,
among the reactive 6:6 bonds of C70 the Ca-Cb bonds
at the poles of the molecule have the highest degree of
pyramidalization, thus are expected to be the most
reactive.4b In fact, that C70 is bound to metals in an η2-
fashion with the Ca-Cb bonds has been confirmed by
X-ray diffraction analysis for the known C70 metal
complexes.3b,k,4b So, in the double addition product 6,
the C70 is most likely bonded to tungsten atoms through
two Ca-Cb bonds at the poles of the C70 ligand. This
coordination geometry for 6 is consistent with its IR and
31P NMR spectra, since it displays only three bands for
its terminal carbonyls and two groups of 31P NMR
signals. However, since there are three Ca-Cb bonds
on the opposite poles, the exact structure of the double
addition product 6 still remains to be solved in the
future by X-ray diffraction analysis.
their terminal carbonyl ligands.13 Similar to 2, the UV-
vis spectra of 3 and 4 also display three intense bands
between 200 and 400 nm; the new bands appearing at
433.0 nm for 3 and at 430.5 nm for 4, compared with
free C60, suggest that the C60 is coordinated to tungsten
in an η2-fashion in each of the compounds.3i,7e,15
A series of 13C NMR studies of the C60 moiety for
numerous metallofullerenes have been reported such as
for Rh(NO)(PPh3)2(η2-C60) (Cs symmetry, showing 31 sp2
and 1 sp3 resonance signals)16 and Fe(CO)4(η2-C60) (C2v,
showing 16 sp2 and 1 sp3 resonance signals).17 The
chemical shifts of sp2 and sp3 carbon atoms of the C60
core are typically in the regions 175-135 ppm and 85-
50 ppm, respectively. Although 3 possesses Cs sym-
metry, there are only 16 signals in the region 164-137
ppm and one signal at 79.34 ppm in its 13C NMR
spectrum for the carbon atoms of its C60 core. Among
the 17 signals, one represents eight carbons, 10 could
be each assigned to four carbon atoms, and the other
six might be each assigned to two carbon atoms. This
implies that the C60-metal moiety rotation is present
in the solution at room temperature, which renders the
number of 13C NMR signals of the C60 moiety varying
from a 32-line pattern of Cs symmetry to a 17-line
pattern of C2v symmetry.7e,16 It is fortunate that mer
configuration of 3 has been confirmed by crystal X-ray
diffraction analysis (see below). In theory, when the [60]-
fullerene coordinates to two identical metal fragments
in an η2-fashion using its 6:6 bonds, the C60 metal
complex may have eight possible regioisomers.4d How-
ever, the 31P NMR spectrum of 4, except showing
evidence for its mer configuration as mentioned above,
also suggests that the two identical metal fragments
W(CO)3(dppf) in 4 are bonded to 6:6 bonds at the
opposite ends of the C60 portion. In fact, this sort of
regioisomer was also observed for diiridium fullerene
complexes.4a,d
Syn th esis a n d Sp ectr oscop ic Ch a r a cter iza tion
of m er -W(CO)3(d p p f)(η2-C70) (5) a n d [m er -W(CO)3-
(d p p f)]2(η2,η2-C70) (6). Similarly, upon photolysis of an
equimolar mixture of W(CO)4(dppf) and C70 in chlo-
robenzene at room temperature for 2 h, a brown solution
was formed. Further treatment of this solution by TLC
afforded 5 in 51% yield and 6 in 48% yield, as shown in
eq 4.
Cr ysta l Str u ctu r es of W(CO)4(d p p f) a n d 3. For-
tunately, we succeeded in carrying out the X-ray dif-
fraction analyses for starting material W(CO)4(dppf) and
its C60 derivative 3. The molecular ORTEP diagrams of
W(CO)4(dppf) and 3 are shown in Figures 3 and 4,
(16) Green, M. L. H.; Stephens, A. H. H. J . Chem. Soc., Chem.
Commun. 1997, 793.
(17) Douthwaite, R. E.; Green, M. L. H.; Stephens, A. H. H.; Turner,
J . F. C. J . Chem. Soc., Chem. Commun. 1993, 1522.

5346 Organometallics, Vol. 19, No. 25, 2000
Song et al.
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 3
W(1)-C(1)
W(1)-C(2)
W(1)-P(1)
W(1)-P(2)
W(1)-C(62)
W(1)-C(63)
W(1)-C(61)
C(1)-C(6)
C(1)-C(2)
2.316(4)
2.338(4)
2.5403(12)
2.6375(13)
2.008(6)
2.014(6)
2.036(6)
1.471(6)
1.489(6)
C(1)-C(9)
1.495(7)
1.483(6)
1.482(6)
2.016(5)
2.070(5)
1.819(5)
1.832(5)
1.360(8)
1.472(9)
C(2)-C(12)
C(2)-C(3)
Fe(1)-C(69)
Fe(1)-C(71)
P(1)-C(64)
P(2)-C(69)
C(22)-C(23)
C(17)-C(18)
C(1)-W(1)-P(2)
P(1)-W(1)-P(2)
C(62)-W(1)-C(63)
C(62)-W(1)-C(61)
120.08(11) C(1)-W(1)-C(2)
37.32(15)
82.13(14)
91.07(14)
90.57(14)
151.29(12)
171.02(11)
88.63(4)
85.8(2)
88.1(2)
C(62)-W(1)-P(1)
C(63)-W(1)-P(1)
C(61)-W(1)-P(1)
C(1)-W(1)-P(1)
C(63)-W(1)-C(61) 173.4(2)
C(62)-W(1)-C(1)
C(63)-W(1)-C(1)
C(61)-W(1)-C(1)
C(62)-W(1)-C(2)
C(63)-W(1)-C(2)
C(61)-W(1)-C(2)
69.18(18) C(2)-W(1)-P(1)
87.53(18) C(62)-W(1)-P(2) 170.63(14)
87.53(18) C(63)-W(1)-P(2)
106.24(18) C(61)-W(1)-P(2)
86.39(18) C(2)-W(1)-P(2)
92.93(19)
92.90(16)
93.54(16)
82.90(11)
(PPh3)2(η2-C60) (1.45(3) Å),3e W(CO)3(dppe)(η2-C60) (1.497-
(8) Å), Mo(CO)3(dppe) (η2-C60) (1.483(10) Å),3k Os3(CO)11-
(η2-C60) (1.42(3) Å),5c RuCl(NO)(PPh3)2(η2-C60) (1.489(7)
Å),3i Ir(CO)Cl(PPh3)2(η2-C60) (1.53(3) Å),3a Mo(CO)3-
(dppb)(η2-C60) (1.477 (5) Å), W(CO)3(dppb)(η2-C60) (1.501-
(11) Å),7e and Cp2Ti(η2-C60) (1.510(2) Å).3m
The influence of such a coordination mode on the
geometry of the C60 moiety is manifested not only in
the lengthening of the C(1)-C(2) bond but also in the
lengthening of the four bonds adjacent to C(1) and C(2)
atoms. That is, as shown in Table 2, the C(1)-C(6),
C(1)-C(9), C(2)-C(3), and C(2)-C(12) bond lengths are
in the range 1.471(6)-1.495(7) Å (average 1.483 Å),
whereas the average C-C distance at the other 5:6 ring
junctions is 1.446 Å (1.45 Å in free fullerene).2d In
addition, the two coordinated carbon atoms C(1) and
C(2) are pulled away from the fullerene cage, as a result
of which the C(1) and C(2) atoms deviate from the
planes of the corresponding six-membered rings by ca.
0.16 and 0.18 Å, respectively. The distances from the
centroid of the C60 ligand to the C(1) and C(2) atoms
are 3.711 and 3.746 Å, whereas the corresponding
distance to the other carbon atoms of C60 are in the
range 3.501-3.548 Å.
F igu r e 3. ORTEP diagram of W(CO)4(dppf) with ellipsoids
drawn at 30% probability.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for W(CO)4(d p p f)
W(1)-C(14)
W(1)-C(12)
W(1)-C(11)
W(1)-C(13)
W(1)-P(1)
1.964(8)
1.982(7)
2.021(7)
2.029(7)
2.5332(16)
W(1)-P(2)
Fe(1)-C(1)
Fe(1)-C(4)
P(1)-C(1)
P(2)-C(6)
2.5627(17)
2.017(6)
2.080(7)
1.812(6)
1.833(7)
C(12)-W(1)-P(1)
C(14)-W(1)-C(13)
C(12)-W(1)-C(13)
89.3(2) C(11)-W(1)-P(1)
87.4(3) C(13)-W(1)-P(1)
88.1(3) C(14)-W(1)-P(2)
84.5(2)
98.99(19)
89.7(2)
C(11)-W(1)-C(13) 172.2(3) C(12)-W(1)-P(2) 174.3(2)
C(14)-W(1)-P(1)
C(14)-W(1)-C(12)
C(14)-W(1)-C(11)
C(12)-W(1)-C(11)
172.1(2) C(11)-W(1)-P(2)
86.1(3) C(13)-W(1)-P(2)
88.6(3) P(1)-W(1)-P(2)
85.0(3)
98.8(2)
87.87(18)
95.24(5)
whereas Tables 2 and 3 list their selected bond lengths
and angles, respectively.
The metal W atom has a slightly distorted octahedral
geometry. The atoms W(1), C(1), C(2), C(62), P(1), and
P(2) are coplanar (the plane equation gives a mean
deviation of 0.0444 Å). A mer configuration around the
W atom is adopted for the dppf and C60 ligands, where
one phosphorus atom, P(1), of the chelating diphosphine
is trans to C60 and the other, P(2), is cis to that center.
Since the trans effect of the carbonyl ligand C(62)O(2)
is stronger than that of the C60 ligand, the W(1)-P(2)
bond length (2.6375(13) Å) is longer than that of W(1)-
P(1) (2.5403(12) Å). The bite angle of the dppf ligand,
P(1)-W(1)-P(2) (88.63(4)°), is smaller than those in
W(CO)4(dppf) (95.24(5)°), W(CO)3(dppf)(CH3CN) (98.05-
(6)°),8 and Mo(CO)4(dppf) (95.28(2)°),9 but larger than
that of the dppe ligand in W(CO)3(dppe)(η2-C60) (79.0-
(1)°)3k or that of the dppb in W(CO)3(dppb)(η2-C60)
(77.04(8)°).7e
Figure 3 shows that W(CO)4(dppf) contains a dppf
ligand coordinated via its two P atoms to the W atom
of the W(CO)4 moiety, thus completing a cis octahedral
coordination geometry for the W atom. However, the
configuration at the metal center is distorted from a
normal octahedral geometry, with the P(1)-W(1)-P(2)
angle of 95.24(5)° increased from the ideal value of 90°,
but comparable with those in fac-W(CO)3(dppf)(CH3CN)
(98.05(6)°)8 and Mo(CO)4(dppf) (95.28(2)°).9
Figure 4 shows that 3 has a C60 ligand bound to the
W atom of the W(CO)3(dppf) unit in an η2-fashion with
the C(1)-C(2) bond between two six-membered rings,
which results in a significant elongation of the fullerene
C(1)-C(2) bond. The C(1)-C(2) bond length is 1.489(6)
Å, which is considerably longer than the corresponding
bond in free C60 (6:6 bond length 1.38 Å)2d and the
average bond length (1.386 Å) of the other 29 6:6 bonds
in 3, due to the metal-to-C60 π-back-donation.2a Such
bond lengthening is also observed in other η2-C60 metal
complexes, such as in Pt(PPh3)2(η2-C60) (1.50(3) Å),1 Pd-
It is interesting to compare the dppf ligand of the C60
derivative 3 with that of its precursor W(CO)4(dppf). As
seen from Figures 3 and 4, the two dppf ligands are
chelated to the W atom via P(1) and P(2) located on one

Organotransition Metal Fullerene Derivatives
Organometallics, Vol. 19, No. 25, 2000 5347
F igu r e 4. ORTEP diagram of 3 with ellipsoids drawn at 30% probability.
side of the ligands. The two cyclopentadienyl rings in
dppf are planar within experimental error (the mean
deviations are 0.0028 and 0.0052 Å for 3 and 0.0005 and
0.0077 Å for W(CO)4(dppf)), whereas they deviate
slightly from parallel with dihedral angles of 2.52(0.31)°
and 3.73(0.35)° for W(CO)4(dppf) and 3, respectively.
The C-C bond lengths in the cyclopentadienyl rings are
all in the range 1.442(7)-1.400(8) Å. The P-C(Cp) bond
lengths are 1.812(6) and 1.833(7) Å for W(CO)4(dppf)
and 1.829(5) and 1.832(5) Å for 3. The Fe-C(Cp) bond
lengths range from 2.017(6) to 2.080(7) Å for W(CO)4-
(dppf) and from 2.016(5) to 2.070(5) Å for 3. The Fe-
C(Cp) distances are shortest for the substituted C(1)
(2.017(6) Å) and C(6) (2.041(6) Å) in W(CO)4(dppf) and
for C(69) (2.016(5) Å) and C(64) (2.023(5) Å) in 3, which
indicates the cyclopentadienyl rings are closer to the
substituted carbon side.
Apart from the original presence of minor traces of
free C60 (hereafter, starred peaks underline the free
fullerene reductions originating either from impurities
or from byproducts of redox processes), 3 displays three
main fullerene-centered reductions with features of
chemical reversibility, which are shifted toward more
negative potential values by about 0.2 V with respect
to the corresponding processes of free C60. By contrast,
2 proves to be notably unstable toward electron addi-
tions in that the second one-electron reduction just
triggers C60 decomplexation. As a matter of fact, the
most cathodic reduction now clearly involves the reduc-
tion of the fulleride dianion released as a consequence
of the second cathodic step of the metallofullerene.
Figure 6 shows that the same fullerene-releasing
effect occurs as a consequence of the metal-centered
oxidations also in the case of the stable-to-reduction 3.
As a matter of fact, it is well evident that in the
backscan the reductions of the free fullerene prevail over
those of the metallocomplex.
In this connection, on the basis of previous results on
the strictly related complexes containing redox-inactive
diphosphines Mo(CO)3(dppe)(η2-C60) and W(CO)3(dppb)
(η2-C60),21 we are keen to attribute the first irreversible
oxidation at about 1 V to the two-electron oxidation of
the Mo(0) or W(0) center. More intriguing appears the
localization of the expected one-electron oxidation of the
coordinated dppf ligand. Under the present experimen-
tal conditions, free dppf undergoes a one-electron oxida-
tion (coupled to chemical complications) at E°′ ) +0.89
V. Because of the ill-defined profiles obtained in the
anodic region for all the complexes, we do not venture
Electr och em ica l Stu d ies of fa c/m er -Mo(CO)3-
(d p p f)(η2-C60) (2), m er -W(CO)3(d p p f)(η2-C60) (3), a n d
m er -W(CO)3(d p p f)(η2-C70) (5). Electrochemical studies
on fullerenes exohedrally functionalized with ferrocene
structural units are scanty,18-20 although the coupling
between the electron-donating ferrocene moieties and
the electron-withdrawing fullerenes could potentially
trigger interesting electronic properties in the field of
high conductive materials or materials able to exhibit
nonlinear optical properties.
Figure 5 compares the cyclic voltammetric cathodic
response exhibited by the molybdenum complex 2 with
that of the tungsten analogue 3 in 1,2-dichlorobenzene
solution.
(18) Maggini, M.; Karlsson, A.; Scorrano, G.; Sandona`, G.; Farnia,
G.; Prato, M. J . Chem. Soc., Chem. Commun. 1994, 589.
(19) Bildstein, B.; Schweiger, M.; Angleitner, H.; Kopacka, H.;
Wurst, K.; Ongania, K.-H.; Fontani, M.; Zanello, P. Organometallics
1999, 18, 4286.
(20) Bashilov, V. V.; Magdesieva, T. V.; Kravchuk, D. N.; Petrovskii,
P. V.; Ginzburg, A. G.; Butin, K. P.; Sokolov,V. I. J . Organomet. Chem.
2000, 599, 37.
(21) Zanello, P.; Laschi, F.; Fontani, M.; Song, L.-C.; Zhu, Y.-H. J .
Organomet. Chem. 2000, 593-594, 7.

5348 Organometallics, Vol. 19, No. 25, 2000
Song et al.
F igu r e 6. Cyclic voltammetric response recorded at a
platinum electrode on a 1,2-C6H4Cl2 solution containing
[NBu4][PF6] (0.08 mol dm-3) and 3 (0.3 × 10-3 mol dm-3).
T ) 0 °C. Scan rate 0.2 V s-1
.
(η2-C60)Mo(CO)3(dppe) and (η2-C60)W(CO)3(dppb).21 This
seems to indicate that no significant electronic interac-
tion takes place between the ferrocendiyldiphosphine
and the fullerene unit. As above-discussed, unfortu-
nately we cannot further support such a conclusion
making use of the eventual anodic shift of dppf oxida-
tion.
F igu r e 5. Cyclic voltrammetric responses recorded at a
platinum electrode on 1,2-C6H4Cl2 solutions containing
[NBu4][PF6] (0.08 mol dm-3) and (a) 2 (0.4 × 10-3 mol
dm-3); (b) 3 (0.3 × 10-3 mol dm-3). T ) 0 °C. Scan rate 0.2
V s-1
.
Figure 7 shows the cyclic voltammetric response of 5
in comparison with that of free C70.
to identify the oxidation at about 1.2 V as due to such
a process, also in view of the fact that it follows a
framework-destroying process.
At variance with 3, which proved to be stable toward
multiple one-electron reductions, 5 adds reversibly the
first two electrons, whereas the third reduction induces
releasing of C703-. This account for the fact that the
fourth reduction looks like a two-electron reduction: the
fourth one-electron reduction of the metallofullerene
The electrode potentials of the above-mentioned redox
changes are compiled in Table 4, together with those of
the C70 complex 5, which will be discussed below.
It must be preliminarily pointed out that with respect
to the theroretical peak-to-peak separation of 60 mV
expected for electrochemically reversible one-electron
processes, the large departures here observed must be
attributed to the high solution resistivity caused by the
low solubility of tetrabutylammonium supporting elec-
trolyte in dichlorobenzene solvent. As a matter of fact,
both C60 and C70, which are known to undergo electro-
chemically reversible one-electron reductions, also dis-
play large peak-to-peak separations.
The negative shift of the fullerene-centered reductions
caused by appended metal fragments with respect to
free fullerene is a rather common feature in metallo-
fullerene electrochemistry;22 the effect is substantially
due to the prevalence of the partial breaking of the
double-bond conjugation operated by the η2-coordination
(which makes the reduction more difficult) over the
inductive effects of the exohedral metallic fragment
(which can favor or disfavor the reduction). Rather
unexpectedly, in the present case, in which a ferrocene
donor ligand is present in the appended diphosphine,
the negative shift of about 0.2 V is substantially similar
to that previously recorded for the related complexes
3-
couples with that of the released C70 (ECE mecha-
nism).
It is useful to note from Table 4 that the negative shift
in reduction potentials induced by the W(CO)3(dppf)
fragment with respect to free C70 is about 0.1 V, i.e.,
significantly lower than that induced by the same
fragment with respect to C60. Such an effect has been
previously observed for the couple Mo(CO)2(phen)(dbm)-
(η2-C60)/Mo(CO)2(phen)(dbm)(η2-C70),23 thus supporting
that the double-bond saturation operated by η2-metal
coordination to C70 is lower than that relative to C60.
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were carried out under
an atmosphere of highly purified nitrogen using standard
Schlenk or vacuum-line techniques. Acetonitrile and chlo-
robenzene were dried by distillation from P2O5 and CaH2 under
nitrogen. Pentane and THF were distilled under nitrogen from
sodium/benzophenone ketyl. [60]Fullerene (99.9%) and [70]-
fullerene (98%) were of commercial origin. Mo(CO)3(CH3CN)3,24
1,1′-bis(diphenylphosphino)ferrocene (dppf),25 Mo(CO)4(dppf),26
and W(CO)4(dppf)26 were prepared according to literature
(22) Zanello, P. Electrochemical and Structural Aspects of Metal-
lofullerenes. In Chemistry at the Beginning of the Third Millennium;
Fabbrizzi, L., Poggi, A., Eds., Springer-Verlag: Heidelberg, 2000; p
247.
(23) Zanello, P.; Laschi, F.; Cinquantini, A.; Fontani, M.; Tang, K.;
J in, X.; Li, L.Eur. J . Inorg. Chem. 2000, 1345.
(24) Tate, D. P.; Knipple, W. R.; Augl, J . M. Inorg. Chem. 1962, 1,
433.

Organotransition Metal Fullerene Derivatives
Organometallics, Vol. 19, No. 25, 2000 5349
Ta ble 4. F or m a l Electr od e P oten tia ls (in V, vs SCE) a n d P ea k -to-P ea k Sep a r a tion (in m V) for th e Red ox
Ch a n ges Exh ibited by th e Meta llofu ller en es M(CO)3(d p p f) (η2-Cx) (x ) 60, 70; M ) Mo, W) a n d Rela ted
Sp ecies in 1,2-C6H4Cl2 Solu tion
fullerene-centered reductions
Mo(W)-centered oxidation
a
a
a
a
M [Cx]
T (°C)
E°′0/-
∆Ep
E°′-/2-
∆Ep
E°′2-/3-
∆Ep
E°′3-/4-
∆Ep
Ep
W [C60
Mo[C60
C60
]
20
0
20
0
20
0
20
0
-0.78
-0.81
-0.79
-0.79
-0.60
-0.63
-0.73
-0.74
-0.53
-0.57
150
220
140
170
210
208
180
162
186
260
-1.17
-1.19
-1.21a,b
-1.16
-1.00
-1.04
-1.04
-1.11
-0.92
-0.96
140
230
-1.74a,b
-1.70
+1.00
250
c
]
+0.95
c
180
230
240
200
154
202
276
-1.74a,b
-1.45
270
280
-1.48
W [C70
C70
]
-1.54a,b
-1.47
+0.97
c
182
192
300
20
0
-1.33
-1.75
174
-1.39
a
b
Measured at 0.2 Vs-1
.
Peak potentials for irreversible processes. c Not measured.
as golden crystals. Mp: 210-212 °C dec. Anal. Calcd for
C39H31FeMoNO3P2: C, 60.41; H, 4.03; N, 1.81. Found: C, 60.49;
H, 4.23; N, 1.86. IR (KBr disk): νCtO, 1926(vs), 1826(vs), 1808-
(vs) cm-1. 1H NMR (200 MHz, CDCl3, TMS): 1.98(s, 3H, CH3),
4.24(s, 4H, C5H4), 4.29(s, 4H, C5H4), 7.20-7.60(m, 20H, 4C6H5,)
ppm. 31P NMR (81 MHz, CDCl3, H3PO4): 37.86(s) ppm.
Syn th esis of fa c/m er -Mo(CO)3(d p p f)(η2-C60) (2). Meth od
(i). A 100 mL two-necked flask equipped with a stir-bar, a N2
inlet tube, and a serum cap was charged with 0.036 g (0.050
mmol) of C60 and 50 mL of chlorobenzene. The mixture was
stirred at room temperature until all C60 was dissolved. To
the solution was added 0.039 g (0.050 mmol) of complex 1, and
the reaction mixture was heated to about 90 °C and stirred at
this temperature for 2 h, during which time the purple solution
turned dark green. The resulting solution was evaporated at
reduced pressure, and the residue was separated by column
chromatography using 1:1 (v/v) toluene-light petroleum ether
as eluent under an atmosphere of highly purified nitrogen.
From the first purple band unreacted C60 was recovered, and
from the chlorophyll-green band 0.015 g (21%) of 2 as a dark
green solid was obtained.
Meth od (ii). A 100 mL photoreactor equipped with a N2
inlet tube and a serum cap was charged with 0.072 g (0.10
mmol) of C60, 0.078 g (0.10 mmol) of Mo(CO)4(dppf), and 50
mL of chlorobenzene. The photoreactor containing the result-
ing purple solution was evacuated to a pressure of ca. 0.1
mmHg, and then the solution was irradiated by a water-cooled
UV 450 W mercury vapor lamp for 2 h, with periodic evacu-
ation of CO to give a dark green solution. Through the same
workup used in method (i) 0.126 g (87%) of 2 was obtained.
Recrystallization from toluene and pentane gave complex 2
F igu r e 7. Cyclic voltammetric responses recorded at a
platinum electrode on 1,2-C6H4Cl2 solutions containing
[NBu4][PF6] (0.08 mol dm-3) and (a) C70 (0.5 × 10-3 mol
dm-3); (b) 5 (0.2 × 10-3 mol dm-3)). T ) 20 °C.
as dark green crystals. Mp: 300 °C dec. Anal. Calcd for C97H28
-
FeMoO3P2: C, 80.07; H, 1.97. Found: C, 79.98; H, 2.05. IR
(KBr disk): νCtO, 2000(s), 1972(w), 1936(s), 1920(s), 1882(vs);
procedures. Products were separated by thin-layer chroma-
tography (TLC glass plates of 20 × 25 × 0.25 cm coated with
silica gel 60H) or by column chromatography (30 × 2.5 cm
column with silica gel). Melting points were determined on a
Yanaco MP-500 apparatus. Elemental analysis and FAB-MS
were performed on a Yanaco CHN Corder MT-3 analyzer and
a Zabspec spectrometer. IR and UV-vis spectra were recorded
on a Bio-Rad FTS 135 and a Shimadzu UV-2401/PC spectrom-
eters. 1H NMR, 31P NMR, and 13C NMR spectra were obtained
on a Bruker AC-P200 or a UNITY Plus-400 spectrometer.
ν
C60, 1434(m), 1185(w), 585(w), 526(s) cm-1. UV-vis (THF, 9.21
× 10-6 M) λmax(log ꢀ): 239.0 (4.94), 256.7 (5.25), 329.3 (4.74),
436.3 (3.89), and 598.7 (3.55) nm. 1H NMR (200 MHz, CS2,
TMS): 4.13 (s, 4 H, C5H4), 4.49, 4.65 (2s, 4 H, C5H4), 7.18-
7.69 (m, 20 H, 4C6H5) ppm. 31P NMR (81 MHz, C6D4Cl2, H3-
PO4): 39.31(d, 1P, J P-P ) 33.2 Hz), 33.56(s, 2P), 29.86(d, 1P,
J P-P ) 33.2 Hz) ppm.
Syn th esis of m er -W(CO)3(d p p f)(η2-C60) (3) a n d [W(CO)3-
(d p p f)]2(η2,η2-C60) (4). The same synthetic procedure, namely,
method (ii), for preparation of 2 was employed, except that
0.086 g (0.10 mmol) of tungsten complex W(CO)4(dppf) was
used instead of molybdenum complex Mo(CO)4(dppf) and the
reaction mixture was separated by TLC using 1:1 (v/v)
toluene-light petroleum ether as eluent under anaerobic
conditions. The first band gave a small amount of C60. From
the chlorophyll-green band 0.135 g (87%) of 3 was obtained,
which was further recrystallized from THF and pentane to give
3 as dark green crystals. Mp: 300 °C dec. Anal. Calcd for
Syn th esis of fa c-Mo(CO)3(d p p f)(CH3CN) (1). A 100 mL
two-necked flask equipped with a stir-bar, a serum cap, and a
reflux condenser topped with a N2 inlet tube was charged with
0.15 g (0.50 mmol) of Mo(CO)3(CH3CN)3, 0.277 g (0.50 mmol)
of dppf, and 35 mL of acetonitrile. The mixture was stirred
and refluxed for 30 h. The warm solution was filtered and
refrigerated overnight. A crop of 0.198 g (51%) of 1 was isolated
(25) Bishop, J . J .; Davison, A.; Katcher, M. L.; Lichtenberg, D. W.;
Merrill, R. E.; Smart, J . C. J . Organomet. Chem. 1971, 27, 241.
(26) Rudie, A. W.; Lichtenberg, D. W.; Katcher, M. L.; Davison, A.
Inorg. Chem. 1978, 17, 2859.
C
97H28FeO3P2W: C, 75.51; H, 1.83. Found: C, 75.53; H, 2.04.
IR (KBr disk): νCtO, 1998(s), 1936(s), 1868(vs); νC60: 1434(m),

5350 Organometallics, Vol. 19, No. 25, 2000
Song et al.
Ta ble 5. Cr ysta l Da ta a n d Str u ctu r e Refin em en ts for fa c-Mo(CO)3(d p p f)(CH3CN)‚0.5H2O, W(co)4(d p p f), a n d
m er -W(CO)3(d p p f)(η2-C60)‚C6H5CH3
fac-Mo(CO)3 (dppf)(CH3CN)‚0.5H2O
W(CO)4(dppf)
mer-W(CO)3 (dppf)(η2-C60)‚C6H5CH3
mol formula
C39H32FeMoNO3.5P2
784.39
C38H28FeO4P2W
850.24
C104H36FeO3P2W
1634.97
mol wt
temp/K
cryst syst
298
298
298
P21/n
P1h
triclinic
P1h
triclinic
space group
monoclinic
12.0503(8)
21.5612(16)
13.7949(10)
a/Å
10.2520(10)
10.9481(10)
18.0955(17)
82.602(2)
76.713(2)
85.280(2)
1957.3(3)
2
13.7178(7)
15.4457(8)
17.5888(10)
72.1920(10)
75.3730(10)
64.7640(10)
3177.1(3)
2
b/Å
c/Å
R/deg
â/deg
96.911(2)
γ/deg
V/Å3
3558.1(4)
4
Z
Dc/g‚cm-3
1.464
1.443
1.709
abs coeff/mm-1
F(000)
0.889
3.423
2.155
1596
836
1628
θ range for data collecn/deg
no. of rflns
1.76 to 25.03
14 691
1.88 to 25.03
8154
1.23 to 25.03
13 177
no. of indep rflns
Rint
completeness to θ ) 25.03°
no. of data/restraints/params
goodness of fit on F2
final R indices [I>2σ(I)]
6295
6836
11 142
0.0218
0.0252
0.0254
99.9%
99.3%
99.3%
6295/3/445
1.053
6836/0/415
1.027
11 142/0/988
1.008
R1 ) 0.0254,
wR2 ) 0.0592
R1 ) 0.0332,
wR2 ) 0.0625
0.334 and -0.267
R1 ) 0.0402,
wR2 ) 0.0994
R1 ) 0.0551,
wR2 ) 0.1055
1.306 and -1.215
R1 ) 0.0370,
wR2 ) 0.0812
R1 ) 0.0536,
wR2 ) 0.0884
0.632 and -0.944
R indices (all data)
largest diff peak and hole/e Å-3
1186(w), 585(w), 526(s) cm-1. UV-vis (THF, 8.30 × 10-6 M)
4.12(s, 4 H, C5H4), 4.50, 4.62(2s, 4 H, C5H4), 7.10-7.85(m, 20H,
4C6H5) ppm. 31P NMR (161.95 MHz, CDCl3, H3PO4): 16.65-
(br, 2P), 10.20(br, 2P) ppm. FAB-MS, m/z: 1663 [W(CO)3(dppf)
(η2-C70)H+,184W, 56Fe]. The third red-brown band gave 0.030 g
(48%) of 6 as a red-brown solid. Mp: 300 °C dec. Anal. Calcd
for C144H56Fe2O6P4W2: C, 69.59; H, 2.27. Found: C, 69.52; H,
2.37. IR (KBr disk): νCtO, 1998(s), 1935(s), 1870(vs); νC70, 1630-
(m), 1433(s), 1037(m), 795(w), 673(w), 536(m) cm-1. UV-vis
(THF, 4.43 × 10-6 M) λmax (log ꢀ): 238.1 (5.14), 330.0(4.51),
362.5(4.45), 378.0(4.43), 456.7(4.42) nm. 1H NMR(200 MHz,
CS2, TMS): 4.10(br, 4 H, C5H4), 4.47, 4.63 (2s, 4 H, C5H4),
7.20-7.70(m, 20H, 4C6H5) ppm. 31P NMR(161.95 MHz, C6D6,
H3PO4): centered at 12.27(m, 2P), centered at 5.54(m, 2P) ppm.
X-r a y Cr ysta llogr a p h y. Single crystals of 1 suitable for
X-ray diffraction analysis were obtained by evaporation of its
acetonitrile solution at about 5 °C, whereas single crystals of
W(CO)4(dppf) and 3 were obtained by evaporation of their
toluene solutions at room temperature. The single crystal of
1 (0.30 × 0.25 × 0.15 mm), that of W(CO)4(dppf) (0.20 × 0.25
× 0.30 mm), and that of 3 (0.20 × 0.25 × 0.30 mm) were glued
to a glass fiber and mounted on a Bruker SMART 1000
automated diffractometer. Data were collected at room tem-
perature, using Mo KR graphite monochromator radiation (λ
) 0.71073 Å) in the ω scanning mode. Absorption corrections
were performed using SADABS for all of them. The structures
were solved by direct methods using the SHELXTL-97 pro-
gram and refined by full-matrix least-squares techniques
(SHELXL-97) on F2. Hydrogen atoms were located by using
the geometric method. The weighting scheme w ) 1/σ2(Fo2) +
λmax(log ꢀ): 238.2(5.05), 257.1(5.14), 333.5(4.58), 433.0 (4.08),
1
598.3(3.64) nm. H NMR (200 MHz, CS2, TMS): 4.15(s, 4 H,
C5H4), 4.52, 4.70 (2s, 4 H, C5H4), 7.20-7.70(m, 20H, 4C6H5)
ppm. 31P NMR (81 MHz, C6D4Cl2, H3PO4): 18.47(d, J P-P ) 30.8
Hz, 1P), 12.79(d, J P-P ) 30.8 Hz, 1P) ppm. FAB MS: m/z 1542
(W(CO)3(dppf)(η2-C60)+, 56Fe, 184W). 13C NMR (100.6 MHz,
CDCl3, TMS, 25 °C): 206.00 (1C, CO), 204.57(1C, CO), 203.95-
(1C, CO), 163.70(4C), 147.46(4C), 146.61(2C), 145.55(4C),
145.29(2C), 145.18(4C), 144.64(8C), 143.94(4C), 143.36(4C),
142.90(2C), 142.67(4C), 142.17(4C), 142.03(4C), 140.20(4C),
137.99(2C), 137.77(2C), 79.34(2C)(C60 resonances), 135.30(d,
2
2J P-C ) 10.8 Hz), 134.59(d, J P-C ) 10.8 Hz), 133.45(d, J )
6.1 Hz), 133.40(d, J ) 5.4 Hz), 131.08(d, J ) 30.78 Hz), 130.00-
(s), 128.58(s), 128.25(s) (P(C6H5)2 resonances); 77.48, 76.19,
75.33, 74.59, 72.45, 71.34 (C5H4 resonances) ppm. The third
band gave 0.015 g (13% based on W(CO)4(dppf)) of 4, which
was recrystallized from THF and pentane to afford 4 as a black
solid. Mp: 300 °C dec. Anal. Calcd for C134H56Fe2O6P4W2: C,
68.05; H, 2.39. Found: C, 67.78; H, 2.61. IR (KBr disk): νCtO
,
1995(s), 1929(s), 1870(vs); νC60: 1434(m), 804(s), 605(m), 514-
(m) cm-1. UV-vis (THF, 8.46 × 10-6 M) λmax (log ꢀ): 239.3-
(5.18), 255.5(5.20), 333.5(sh, 4.67), 430.5(4.21), 599.0(3.65) nm.
1H NMR (200 MHz, CS2, TMS): 4.02-4.28(m, 4 H, C5H4),
4.40-4.80(m, 4 H, C5H4), 7.10-7.80(m, 20H, 4C6H5) ppm. 31P
NMR (81 MHz, CS2, H3PO4): 23.67(s, 2P), 16.94(s, 2P) ppm.
Syn th esis of m er -W(CO)3(d p p f)(η2-C70) (5) a n d [m er -
W(CO)3(d p p f)]2(η2,η2-C70) (6). The same synthetic procedure,
namely, method (ii), for preparation of 2 was utilized, except
that 0.043 g (0.10 mmol) of tungsten complex W(CO)4(dppf)
and 0.042 g (0.05 mmol) of C70 were used in place of molyb-
denum complex Mo(CO)4(dppf) and C60. The reaction mixture
was separated by TLC using 1:1 (v/v) toluene-light petroleum
ether as eluent under anaerobic conditions. The first band gave
a small amount of C70. From the second band was obtained
0.042 g (51%) of 5, which was recrystallized from THF and
pentane to afford 5 as a black solid. Mp: 300 °C dec. Anal.
Calcd for C107H28FeO3P2W: C, 77.28; H, 1.70. Found: C, 77.07;
(0.0777P)2 (where P ) (Fo + 2Fc2)/3) was applied to the data
2
for 1, w ) 1/σ2(Fo2) + (0.0578P)2 (where P ) (Fo + 2Fc2)/3)
2
was applied to the data for W(CO)4(dppf), and w ) 1/σ2(Fo2) +
(0.0422P)2 (where P ) (Fo + 2Fc2)/3) was applied to the data
2
for 3. The crystal data and structural refinements details are
listed in Table 5.
Electr och em istr y. Materials and apparatus for electro-
chemistry have been described elsewhere.27 1,2-Dichloroben-
zene, anhydrous, 99% (Aldrich), was used as solvent; electro-
chemical grade [NBu4][PF6] (Fluka) was used as supporting
electrolyte (0.08 mol dm-3). All the potential values are
H, 1.95. IR (KBr disk): νCtO, 1999(s), 1937(s), 1870(vs); νC70
:
1636(m), 1433(s), 1123(w), 1037(w), 795(w), 673(s), 672(m),
535(m) cm-1. UV-vis (THF, 4.93 × 10-6 M) λmax (log ꢀ):
239.5(5.39), 330.0(sh, 4.74), 350.0(4.69), 377.5(4.65), 426.9(4.60),
457.1(4.63), 598.3(4.12) nm. 1H NMR (200 MHz, CS2, TMS):
(27) Zanello, P.; Laschi, F.; Fontani, M.; Mealli, C.; Ienco, A.; Tang,
K.; J in, X.; Li, L. J . Chem. Soc., Dalton Trans. 1999, 965.

Organotransition Metal Fullerene Derivatives
Organometallics, Vol. 19, No. 25, 2000 5351
referred to the saturated calomel electrode (SCE). Under the
present experimental conditions, the one-electron oxidation of
ferrocene occurs at E°′ ) +0.55 V at +20 °C and E°′ ) +0.56
V at 0 °C.
for financial support. Piero Zanello gratefully acknowl-
edges the financial support of the University of Siena.
Su p p or tin g In for m a tion Ava ila ble: Full tables of crystal
data, atomic coordinates and thermal parameters and bond
lengths and angles for 1, W(CO)4(dppf), and 3. This material
is available free of charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. We are grateful to the National
Natural Science Foundation of China, the Research
Fund for the Doctoral Program of Higher Education of
China, and the Laboratory of Organometallic Chemistry
OM000579+