Reactions of halofluorocarbons with group 6 complexes M(C5H5)2L (M = Mo, W; L = C2H4, CO). Fluoroalkylation at molybdenum and tungsten, and at cyclopentadienyl or ethylene ligands

Article abstract of DOI:10.1021/ja003339u

The molybdenum(II) and tungsten(II) complexes [MCp₂L] (Cp = η⁵-cyclopentadienyl; L = C₂H₄, CO) react with perfluoroalkyl iodides to give a variety of products. The Mo(II) complex [MoCp₂(C₂H₄) reacts with perfluoro-n-butyl iodide or perfluorobenzyl iodide with loss of ethylene to give the first examples of fluoroalkyl complexes of Mo(IV), MoCp₂(CF₂CF₂CF₂CF₃)I (8) and MoCp₂(CF₂C₆F₅)I (9), one of which (8) has been crystallographically characterized. In contrast, the CO analogue [MoCp₂(CO)] reacts with perfluorobenzyl iodide without loss of CO to give the crystallographically characterized salt, [MoCp₂(CF₂C₆F₅)(CO)] ⁺I^- (10), and the W(II) ethylene precursor [WCp₂(C₂H₄) reacts with perfluorobenzyliodide without loss of ethylene to afford the salt [WCp₂(CF₂C₆F₅) (C₂H₄)]⁺I^- (11). These observations demonstrate that the metal-carbon bond is formed first. In further contrast the tungsten precursor [WCp₂(C₂H₄)] reacts with perfluoro-n-butyl iodide, perfluoro-iso-propyl iodide, and pentafluorophenyl iodide to give fluoroalkyl- and fluorophenyl-substituted cyclopentadienyl complexes WCp(η⁵-C₅H₄R_F)(H)I (12, R_F = CF₂CF₂CF₂CF₃; 15, R_F = CF(CF₃)₂; 16, R_F = C₆F₅); the Mo analogue MoCp(η⁵-C₅H₄R_F)(H)I (14, R_F = CF(CF₃)₂) is obtained in similar fashion. The tungsten(IV) hydrido compounds react with iodoform to afford the corresponding diiodides WCp(η⁵-C₅H₄R_F)I₂ (13, R_F = CF₂CF₂CF₂CF₃; 18, R_F = CF(CF₃)₂; 19, R_F = C₆F₅), two of which (13 and 19) have been crystallographically characterized. The carbonyl precursors [MCp₂(CO)] each react with perfluoro-isopropyl iodide without loss of CO, to afford the exo-fluoroalkylated cyclopentadiene M(II) complexes MCp(η⁴-C₅H₅R_F)(CO)I (21, M = Mo; 22, M = W); the exo-stereochemistry for the fluoroalkyl group is confirmed by an X-ray structural study of 22. The, ethylene analogues [MCp₂(C₂H₄)] react with perfluoro-tert-butyl iodide to yield the products MCp₂[(CH₂CH₂C(CF₃)₃]I (25, M = Mo; 26, M = W) resulting from fluoroalkylation at the ethylene ligand. Attempts to provide positive evidence for fluoroalkyl radicals as intermediates in reactions of primary and benzylic substrates were unsuccessful, but trapping experiments with CH₃OD (to give R_FD, not R_FH) indicate that fluoroalkyl anions are the intermediates responsible for ring and ethylene fluoroalkylation in the reactions of secondary and tertiary fluoroalkyl substrates.

Full text of DOI:10.1021/ja003339u

J. Am. Chem. Soc. 2001, 123, 3279-3288
3279
Reactions of Halofluorocarbons with Group 6 Complexes M(C5H5)2L
(M ) Mo, W; L ) C2H4, CO). Fluoroalkylation at Molybdenum and
Tungsten, and at Cyclopentadienyl or Ethylene Ligands
Russell P. Hughes,*,† Susan M. Maddock,† Ilia A. Guzei,‡ Louise M. Liable-Sands,‡ and
Arnold L. Rheingold‡
Contribution from the Departments of Chemistry Burke Chemistry Laboratory, Dartmouth College,
HanoVer, New Hampshire 03755-3564, and UniVersity of Delaware, Newark, Delaware 19716
ReceiVed September 11, 2000
Abstract: The molybdenum(II) and tungsten(II) complexes [MCp2L] (Cp ) η5-cyclopentadienyl; L ) C2H4,
CO) react with perfluoroalkyl iodides to give a variety of products. The Mo(II) complex [MoCp2(C2H4)] reacts
with perfluoro-n-butyl iodide or perfluorobenzyl iodide with loss of ethylene to give the first examples of
fluoroalkyl complexes of Mo(IV), MoCp2(CF2CF2CF2CF3)I (8) and MoCp2(CF2C6F5)I (9), one of which (8)
has been crystallographically characterized. In contrast, the CO analogue [MoCp2(CO)] reacts with
perfluorobenzyliodidewithoutlossofCOtogivethecrystallographicallycharacterizedsalt,[MoCp2(CF2C6F5)(CO)]+I-
(10), and the W(II) ethylene precursor [WCp2(C2H4)] reacts with perfluorobenzyl iodide without loss of ethylene
to afford the salt [WCp2(CF2C6F5)(C2H4)]+I- (11). These observations demonstrate that the metal-carbon
bond is formed first. In further contrast the tungsten precursor [WCp2(C2H4)] reacts with perfluoro-n-butyl
iodide, perfluoro-iso-propyl iodide, and pentafluorophenyl iodide to give fluoroalkyl- and fluorophenyl-
substituted cyclopentadienyl complexes WCp(η5-C5H4RF)(H)I (12, RF ) CF2CF2CF2CF3; 15, RF ) CF(CF3)2;
16, RF ) C6F5); the Mo analogue MoCp(η5-C5H4RF)(H)I (14, RF ) CF(CF3)2) is obtained in similar fashion.
The tungsten(IV) hydrido compounds react with iodoform to afford the corresponding diiodides WCp(η5-
C5H4RF)I2 (13, RF ) CF2CF2CF2CF3; 18, RF ) CF(CF3)2; 19, RF ) C6F5), two of which (13 and 19) have
been crystallographically characterized. The carbonyl precursors [MCp2(CO)] each react with perfluoro-iso-
propyl iodide without loss of CO, to afford the exo-fluoroalkylated cyclopentadiene M(II) complexes MCp-
(η4-C5H5RF)(CO)I (21, M ) Mo; 22, M ) W); the exo-stereochemistry for the fluoroalkyl group is confirmed
by an X-ray structural study of 22. The ethylene analogues [MCp2(C2H4)] react with perfluoro-tert-butyl iodide
to yield the products MCp2[(CH2CH2C(CF3)3]I (25, M ) Mo; 26, M ) W) resulting from fluoroalkylation at
the ethylene ligand. Attempts to provide positive evidence for fluoroalkyl radicals as intermediates in reactions
of primary and benzylic substrates were unsuccessful, but trapping experiments with CH3OD (to give RFD,
not RFH) indicate that fluoroalkyl anions are the intermediates responsible for ring and ethylene fluoroalkylation
in the reactions of secondary and tertiary fluoroalkyl substrates.
Introduction
involves oxidative addition of the carbon-iodine bond of
perfluoroalkyl iodides.6,7 This route has been shown to be
successful with low-valent late transition-metal centers to give
perfluoroalkyl-metal complexes in which the M-RF bond is
usually shorter than that in hydrocarbon analogues and is
generally considered to be stronger. The mechanism of oxidative
addition of perfluoroalkyl iodides has not been studied in any
detail, and it is not known whether the reactions proceed by a
concerted addition, a stepwise two-electron mechanism, or a
radical pathway. It seems unlikely that a mechanism involving
nucleophilic attack by the metal at carbon is operative, as the
RF-I bond is polarized to give a δ- charge on the carbon
center.8 We have concentrated our synthetic efforts in groups 9
and 10 and have recently described the syntheses and charac-
terization of a series of perfluoroalkyl and perfluorobenzyl
complexes of Co, Rh, and Ir (1) by oxidative addition of the
appropriate RF-I to [M(η5-C5R5)(CO)2],9-12 expanding con-
siderably on the original examples reported by earlier
There is considerable recent interest in the activation of
aliphatic carbon-fluorine bonds by transition metal centers,1,2
and in the use of fluorinated substituents to render catalytically
active transition metal complexes more soluble in “fluorous”
media.3,4 As a consequence, we have focused renewed attention
on the synthesis and chemistry of transition metal fluoroalkyl
complexes, early examples of which have been known since
the 1960s.5
One of the more widely used methods of synthesizing
complexes with transition-metal perfluoroalkyl bonds (M-RF)
† Dartmouth College.
‡ University of Delaware.
(1) Kiplinger, J. L.; Richmond, T. G.; Osterberg, C. E. Chem. ReV. 1994,
94, 373-431.
(2) Burdeniuc, J.; Jedlicka, B.; Crabtree, R. H. Chem. Ber./Recl. 1997,
130, 145-154.
(3) Horva´th, I. T. Acc. Chem. Res. 1998, 31, 641-650.
(4) Studer, A.; Hadida, S.; Ferritto, R.; Kim, S.-Y.; Jeger, P.; Wipf, P.;
Curran, D. P. Science 1997, 275, 823-826.
(5) Stone, F. G. A. EndeaVour 1966, 25, 33-38.
(6) Morrison, J. A. AdV. Inorg. Chem. Radiochem. 1983, 27, 293-316.
(7) Morrison, J. A. AdV. Organomet. Chem. 1993, 35, 211-239.
(8) Wakselman, C.; Lantz, A. In Organofluorine Chemistry; Banks, R.
E., Smart, B. E., Tatlow, J. C., Eds.; Plenum: New York, 1994; pp 177-
194.
(9) Hughes, R. P.; Lindner, D. C.; Rheingold, A. L.; Yap, G. P. A.
Organometallics 1996, 15, 5678-5686.
10.1021/ja003339u CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/16/2001

3280 J. Am. Chem. Soc., Vol. 123, No. 14, 2001
Hughes et al.
workers.13-16 The chemistry of these compounds has proven
interesting, and preliminary examples of facile hydrolysis17 and
hydrogenolysis18 reactions of the R-fluorines have been docu-
mented.
Figure 1. ORTEP diagram of the non-hydrogen atoms of 8, showing
the atom-labeling scheme. Thermal ellipsoids are shown at the 30%
level.
We reasoned that the well-known 18-electron M(II) com-
plexes [MCp2L] (4-7) might provide useful entries to afford
M(IV) fluoroalkyls by the oxidative addition route. Herein we
report the reactions of primary, secondary, and tertiary perfluo-
roalkyl iodides with these complexes to give a variety of
products resulting from fluoroalkylation at the metal or directly
at the organic ligands. Part of this work has been the subject of
a preliminary communication.29
The first complex (2) arising from the formal oxidative
addition of a carbon-fluorine bond to a transition metal center
was reported in 1987.19 At the time, a considerable part of the
driving force was considered to arise from formation of a strong
tungsten-fluorine bond, but subsequent examples of aromatic
C-F bond activation by group 9 and 10 metals illustrate that
early metals are not essential for this process.20-24 Nevertheless,
we were intrigued by the paucity of examples of group 6
fluoroalkyl complexes in general, and with the idea that, if they
could be prepared, they might afford examples of R- or
â-fluorine elimination reactions, or agostic C-F-M interactions,
analogous to those observed in hydrocarbon analogues. Previous
examples of perfluoroalkyl complexes of group 6 metals in
oxidation state (II) have been synthesized by decarbonylation
of perfluoroacyl complexes, such as [Mo(η5-C5R5)(CO)3CORF]
(RF ) CF3, CF2CF3),25,26 or by the metathesis reaction of Cd-
(CF3)2 with [W(η5-C5H5)(CO)3Cl] (M ) Mo, W).27,28 The
tungsten(VI) complex W(CF3)6 has been reported as an unstable
product of the reaction of Cd(CF3)2 with WBr6.6
Results and Discussion
Reaction of [MoCp2(C2H4)] (4) with perfluoro-n-butyl iodide
in THF solution proceeds rapidly at room temperature with
displacement of ethylene, to give the Mo(IV) fluoroalkyl
complex 8, resulting from formal oxidative addition of the C-I
bond to the metal. In contrast to 4, which is an air-sensitive
1
solid, 8 is stable to air in solution for hours. The H NMR
spectrum of 8 shows a single peak for the cyclopentadienyl
ligands and the 19F NMR spectrum shows the expected four
multiplets at δ -61.0, -80.8, -109.3, and -124.7 ppm for the
perfluoro-n-butyl group. A single-crystal X-ray structural de-
termination of 8 confirmed the overall molecular architecture.
An ORTEP diagram is shown in Figure 1 and crystallographic
information is presented in Table 1. The complex has the same
general geometry as similar neutral complexes of the type
[M(η5-C5H5)2X2] (M ) Mo, W).30-36 There is some disorder
in the fluorine atom positions in the perfluorobutyl ligand. The
Mo-C(11) bond length of 2.277(11) Å is not significantly
different from the 2.284(10) Å observed in the ethyl complex
[MoCp2(C2H5)Cl],30or those of 2.268(4) and 2.272(4) Å in the
dibutyl complex [MoCp2(n-Bu)2].37 It is slightly longer than the
2.248(5) Å found in the Mo(II) complex [Mo(η5-C5Me5)(CO)3-
(CF3)].26
(10) Hughes, R. P.; Husebo, T. L.; Holliday, B. J.; Rheingold, A. L.;
Liable-Sands, L. M. J. Organomet. Chem. 1997, 548, 109-112.
(11) Hughes, R. P.; Husebo, T. L.; Rheingold, A. L.; Liable-Sands, L.
M.; Yap, G. P. A. Organometallics 1997, 16, 5-7.
(12) Hughes, R. P.; Smith, J. M.; Liable-Sands, L. M.; Concolino, T.
E.; Lam, K.-C.; Incarvito, C.; Rheingold, A. L. J. Chem. Soc., Dalton Trans.
2000, 873-879.
(13) King, R. B.; Treichel, P. M.; Stone, F. G. A. J. Am. Chem. Soc.
1961, 83, 3593-3597.
(14) Pitcher, E.; Buckingham, A. D.; Stone, F. G. A. J. Chem. Phys.
1962, 36, 124-129.
(15) McCleverty, J. A.; Wilkinson, G. J. Chem. Soc. 1964, 4200-4203.
(16) Stone, F. G. A. Pure Appl. Chem. 1972, 30, 551-573.
(17) Hughes, R. P.; Lindner, D. C.; Rheingold, A. L.; Liable-Sands, L.
M. J. Am. Chem. Soc. 1997, 119, 11544-11545.
(18) Hughes, R. P.; Smith, J. M. J. Am. Chem. Soc. 1999, 121, 6084-
6085.
(19) Richmond, T. G.; Osterberg, C. E.; Arif, A. M. J. Am. Chem. Soc.
1987, 109, 8091-8092.
(20) Jones, W. D.; Partridge, M. G.; Perutz, R. N. J. Chem. Soc., Chem.
Commun. 1991, 264-266.
(27) Naumann, D.; Varbelow, H.-G. J. Fluorine Chem. 1988, 41, 415.
(28) Preut, H.; Varbelow, H. G.; Naumann, D. Acta Crystallogr., Sect.
C: Cryst. Struct. Commun. 1990, C46, 2460-2462.
(29) Hughes, R. P.; Maddock, S. M.; Rheingold, A. L.; Liable-Sands,
L. M. J. Am. Chem. Soc. 1997, 119, 5988-5989.
(30) Prout, K.; Cameron, T. S.; Forder, R. A.; Critchley, S. R.; Denton,
B.; Rees, G. V. Acta Crystallogr. 1974, B30, 2290.
(31) Schultz, A. J.; Stearley, K. L.; Williams, J. M.; Mink, R.; Stucky,
G. D. Inorg. Chem. 1977, 16, 3303.
(32) Hartwig, J. F.; Xiaoming, H. Angew. Chem., Int. Ed. Engl. 1996,
35, 315.
(33) Hartwig, J. F.; Gala, S. R. D. J. Am. Chem. Soc. 1994, 116, 3661.
(34) Koloski, T. S.; Pestana, D. C.; Carroll, P. J.; Berry, D. H.
Organometallics 1994, 13, 489.
(35) Forder, R. A.; Jefferson, I. W.; Prout, K. Acta Crystallogr. 1975,
B31, 618.
(36) Cameron, T. S.; Prout, C. K. J. Chem. Soc., Dalton Trans. 1972,
1447.
(37) Calhorda, M. J.; Carrondo, M. A. A. F. d. C. T.; Dias, A. R.; Galva˜o,
A. M.; Garcia, M. H.; Martins, A. M.; Piedade, M. E. M. d.; Pinheiro, C.
I.; Rama˜o, C. C.; Simo˜es, J. A. M.; Veiros, L. F. Organometallics 1991,
10, 483.
(21) Belt, S. T.; Helliwell, M.; Jones, W. D.; Partridge, M. G.; Perutz,
R. N. J. Am. Chem. Soc. 1993, 115, 1429-1440.
(22) Selmeczy, A. D.; Jones, W. D.; Partridge, M. D.; Perutz, R. N.
Organometallics 1994, 13, 522-532.
(23) Whittlesey, M. K.; Perutz, R. N.; Moore, M. H. Chem. Commun.
1996, 787-788.
(24) Cronin, L.; Higgitt, C. L.; Karch, R.; Perutz, R. N. Organometallics
1997, 16, 4920-4928.
(25) King, R. B.; Bisnette, M. B. J. Organomet. Chem. 1964, 2, 15-37.
(26) Koola, J. D.; Roddick, D. M. Organometallics 1991, 10, 591-597.

Reactions of Halofluorocarbons with Group 6 Complexes
J. Am. Chem. Soc., Vol. 123, No. 14, 2001 3281
Table 1. Crystal Data and Summary of X-ray Data Collection
8
10
13
18
22
formula
fw
space group
a, Å
b, Å
c, Å
C14H10F9IMo
572.06
P2(1)/c
16.9120(10)
7.4764(6)
12.991(2)
90
92.796(6)
90
1640.6(3)
4
C18H10F7IMoO
598.10
Cc
11.790(2)
10.270(2)
15.530(3)
90
104.37(3)
90
1821.6(6)
4
C14H9F9I2W
785.86
C2/c
36.532(3)
7.5414(6)
13.9090(10)
90
104.090(7)
90
C13H9F7I2W
735.85
C2/c
31.887(3)
7.5394(10)
13.9856(15)
90
100.772(7)
90
3303.1(6)
8
C14H10F7IOW
637.97
P2(1)/c
6.74920(10)
13.5373(4)
37.3724(10)
90
90.5240(10)
90
3414.42(15)
8
R, deg
â, deg
γ, deg
V, Å3
3716.7(5)
8
Z
D(calcd), g/cm3
abs coeff, mm-1
temp, K
diffractometer
radiation
R(F),a %
R(wF2),a %
2.316
2.770
298(2)
2.181
2.489
223(2)
2.809
9.619
298(2)
2.959
10.796
233(2)
2.482
8.643
223(2)
Siemens P4
Mo KR 0.71073 Å
3.79
4.56
14.01
4.45
10.50
3.88
10.25
6.16
14.35
9.21
a Quantity minimized ) R(wF2) ) ∑[w(Fo - Fc2)2]/∑[(wFo )2]1/2; R ) ∑∆/∑(Fo), ∆ ) |(Fo - Fc)|.
2
2
perfluorobenzyl iodide was not as clean, and gave a pale brown
precipitate that contained several products as indicated by NMR
spectroscopy. One of these appeared to be the tungsten analogue
of 10. This reaction was not pursued due to the difficulty of
separating the components from the precipitate. However, when
reaction of [WCp2(C2H4)] (5) and perfluorobenzyl iodide was
carried out in tetrahydrofuran there was immediate formation
of an off-white precipitate, formulated as the ionic compound
11. Like 10, the insolubility of 11 in anything but very polar
solvents such as acetonitrile and dimethyl sulfoxide was
indicative of its ionic nature. The 1H NMR spectrum in
acetonitrile showed two multiplets at δ 2.81 and 2.57 ppm, each
integrating for 2 hydrogens relative to the singlet at δ 5.79 for
the 10 cyclopentadienyl hydrogens, indicating that the ethylene
ligand was still bound to the metal, although not rotating fast
on the NMR time scale. 19F NMR spectroscopy confirmed
coordination of the perfluorobenzyl group to the metal, with
the triplet due to the benzylic fluorines exhibiting satellites due
to coupling to the tungsten nuclear spin (2JFW ) 26 Hz).
Refluxing an acetonitrile solution of 11 overnight did not result
in loss of ethylene and formation of [W(η5-C5H5)2(CF2C6F5)I],
illustrating the kinetic stability of the tungsten ethylene bond.
In further contrast to the behavior of Mo complex 4, reaction
of tungsten analogue 5 with perfluoro-n-butyl iodide does not
result in oxidative addition at the metal center. Instead the major
product arises from fluoroalkyl substitution at one cyclopenta-
dienyl ring with hydride migration to the metal occurring to
form 12. This reaction is analogous to that described in our
preliminary communication,29 and elaborated on below, for
Figure 2. ORTEP diagram of the cation of 10, showing the atom-
labeling scheme. Thermal ellipsoids are shown at the 30% level.
Similarly, reaction of 4 with perfluorobenzyl iodide in THF
or benzene results in displacement of ethylene and oxidative
addition at the metal center giving the dark green complex 9.
1
The H NMR spectrum shows only one peak at δ 5.45 ppm
consistent with two symmetrically equivalent unsubstituted
cyclopentadienyl rings. In the 19F NMR spectrum the benzylic
fluorines appear as a triplet at δ -40.8 ppm (JFF ) 29.8 Hz)
due to coupling to the ortho fluorines on the pentafluorophenyl
ring. Three multiplets are observed for the fluorines on the
pentafluorophenyl ring at -136.7, -158.7, and -163.6 ppm
for the ortho, para, and meta positions, respectively.
In contrast to the ethylene precursor 4 the corresponding
molybdenum carbonyl complex [MoCp2(CO)] (6) reacts with
perfluorobenzyl iodide in benzene to give a pale yellow
precipitate of complex 10, in which the CO ligand is retained
as demonstrated by a strong υCO stretch at 2037 cm-1. The
insolubility of this complex in all but the most polar solvents
(CH3CN, DMSO) implied an ionic structure. The hydrogen
nuclei on the cyclopentadienyl rings gave rise to a singlet in
1
reaction of 5 with perfluoroisopropyl iodide. The H NMR
spectrum of 12 shows four different peaks, each of which
integrates for one hydrogen, for the substituted cyclopentadienyl
ring and a peak for the hydride at δ -10.92 ppm. Because the
wedge ligands are inequivalent, there is no plane of symmetry
in the molecule, and the R-fluorines on the perfluorobutyl group
are diastereotopic, appearing as two strongly coupled doublets
at δ -101.5 and -108.0 ppm (JFF ) 275 Hz) in the 19F NMR
spectrum. While 12 is not the only compound formed in this
reaction, NMR analysis of the crude reaction mixture indicates
that it is the major product (ca. 75%), and the 19F NMR spectrum
shows clearly that there is no formation of any metal fluoroalkyl
product analogous to 8. The chemical shift of the R-fluorines
of the coordinated fluoroalkyl in 8 is δ -61.0 ppm whereas in
12 they appear at δ -101.5 and -108.0 ppm; in contrast to the
W-fluorobenzyl complex 11, no fluorine peaks with tungsten
1
the H NMR spectrum at δ 5.91 ppm, substantially downfield
from that in 9. As in 9 the 19F NMR spectrum the benzylic
fluorines gave rise to a triplet at δ -29.1 ppm, but shifted
significantly downfield from the corresponding resonance in 9,
and the pentafluorophenyl fluorines appeared as three multiplets.
The structure of 10 was confirmed by a single-crystal X-ray
diffraction study. An ORTEP diagram is shown in Figure 2.
Crystallographic data are provided in Table 1. The overall
geometry of the compound is very similar to that of 8 and other
bent group 6 metallocenes.30-36
Reaction of the tungsten analogue [WCp2(CO)] (7) with

3282 J. Am. Chem. Soc., Vol. 123, No. 14, 2001
Hughes et al.
Figure 4. ORTEP diagram 18, showing the atom-labeling scheme.
Thermal ellipsoids are shown at the 30% level.
Figure 3. ORTEP diagram of the non-hydrogen atoms of 13, showing
the atom-labeling scheme. Thermal ellipsoids are shown at the 30%
level.
molar equiv of perfluoroisopropyl iodide with molybdenum or
tungsten precursors 4 or 5 at room temperature rapidly forms
the hydrido complexes 14 and 15 in quantitative yield as
monitored by NMR spectroscopy, although lower yields were
isolated. The ethylene ligand is lost during the reaction and free
ethylene is detected by 1H NMR spectroscopy if the reaction is
carried out in an NMR tube. The IR spectra of the products
exhibited bands at 1958 (14) and 1935 cm-1 (15) attributable
satellites can be observed in the crude reaction mixture. The
reason for the difference in the site of reactivity in going from
molybdenum to tungsten is not clear. Complex 12 is not stable
and on recrystallization undergoes partial conversion to the
diiodide 13. A similar phenomenon has been described for the
bromo hydrides [W(η5-C5H5)(η5-C5H4R)HBr] (R ) Ph, i-Pr),
which convert to the dibromides on workup.38 The instability
of 12 prevented a satisfactory elemental analysis from being
obtained. The diiodide 13 can be synthesized more cleanly by
adding an excess of CHI3 to a dichloromethane solution of 12.
With two identical ligands in the wedge, 13 now has a mirror
plane perpendicular to the plane that contains the metal and
the two iodine atoms. Consequently, the R-fluorines are no
longer diastereotopic and appear as a multiplet at δ -108.0 ppm
in the 19F NMR spectrum, and only two peaks rather than the
1
to υM-H, and their H NMR spectra show hydride peaks at δ
-7.82 (14) and -10.93 ppm (15), with the latter resonance
exhibiting tungsten satellites (JHW ) 60.0 Hz). As with 12, the
hydrogens on the substituted cyclopentadienyl ring appear as
four multiplets and the unsubstituted cyclopentadienyl ring gives
rise to a singlet for all complexes. The 19F NMR spectra of 14
and 15 are similar, with the diastereotopic trifluoromethyl groups
appearing as two doublets of quartets in the 19F NMR spectra.
The quartet coupling and the doublet coupling are of similar
magnitude (JFF ) 10 Hz) and the peaks appear as a quintet.
1
four observed for 12 appear in the H NMR spectrum for the
substituted cyclopentadienyl ring. The X-ray crystal structure
of 13 has been solved and confirms the molecular architecture.
An ORTEP diagram of 13 is shown in Figure 3 and crystal-
lographic information is presented in Table 1. The geometry is
that expected for group 6 metallocene complexes (vide
supra).30-36,39
The tertiary CF resonance couples to both CF3 groups (JFF
)
10 Hz) and to one hydrogen on the cyclopentadienyl ring to
which it is bound. The structure of 4 was determined by X-ray
crystallography and has been published previously.29 The NMR
data are consistent with the solid-state structure and indicate
that the compound in solution has the same geometry as that in
the crystal structure.
This mode of reactivity is not confined to perfluoroalkyl
iodides, since pentafluorophenyl iodide or bromide react in a
similar manner with 5 to form 16 and 17, respectively. The IR
spectra shows a stretch due to υM-H at 1938 (16) and 1895 cm-1
1
(17) and the H NMR spectra exhibit hydride resonances at δ
-11.64 (JHW ) 56.4 Hz) and -11.18 (JHW ) 57.6 Hz) ppm,
respectively. In the 19F NMR spectra of 16 and 17 the
pentafluorophenyl group gives rise to three multiplets of ratio
2:1:2 in the region δ -140 to -160 ppm for the ortho, para,
and meta fluorines, respectively.
Exposure of solutions of 15, 16, and 17 to air results in a
slow color change to green and precipitation of a dark blue/
black solid that is insoluble in common solvents and was not
characterized. From the green solution the diiodo complexes
18 and 19 and the dibromo complex 20 were isolated in low
yield. These complexes can be formed in higher yield on
reaction of the corresponding hydrido complexes with either
1
CHI3 or CHBr3. In the H NMR spectra of 18-20 there are
(38) McNally, J. P.; Glueck, D.; Cooper, N. J. J. Am. Chem. Soc. 1988,
110, 4838.
(39) Jernakoff, P.; Fox, J. R.; Hayes, J. C.; Lee, S.; Foxman, B. M.;
Cooper, N. J. Organometallics 1995, 14, 4493.
Reactions of secondary perfluoroalkyl iodides differ from their
primary analogues in that the reactions are much cleaner and
selective for reaction at a cyclopentadienyl ring. Reaction of 1

Reactions of Halofluorocarbons with Group 6 Complexes
J. Am. Chem. Soc., Vol. 123, No. 14, 2001 3283
now only two peaks for the hydrogens on the substituted
cyclopentadienyl ring which integrate for two hydrogens each.
The trifluoromethyl groups in 18 are now equivalent and give
rise to a doublet in the 19F NMR spectrum at δ -74.4 ppm.
The tertiary fluorine appears as a septet at δ -176.2 ppm. The
solid-state structure of 18 was obtained by a single-crystal X-ray
diffraction; an ORTEP diagram is presented in Figure 4 and
crystallographic information is given in Table 1. The hydrogen
on C(3) is 2.375 Å from F(6), which is less than the sum of the
van der Waals’ radii of 2.67 Å.40
Once again the carbonyl precursors 6 and 7 provide contrast-
ing behavior, and afford new compounds whose structures shed
some light on the pathway for formation of the previously
observed hydrido compounds. When the reaction between ICF-
(CF3)2 and 6 or 7 is carried out in benzene, the orange diene
complexes 21 (M ) Mo) and 22 (M ) W) are formed. These
Figure 5. ORTEP diagram of one of two crystallographically
independent molecules of 22, showing the atom-labeling scheme.
Thermal ellipsoids are shown at the 30% level.
both 21 and 22 the solvent peaks remain sharp at all temper-
atures, as do the peaks in the 19F spectra.
complexes are air stable and could be recrystallized in the open
without decomposition. The 1H NMR spectra of both complexes
show an interesting temperature dependence. At room temper-
ature the peaks in the 1H spectrum of 21 are extensively
broadened but those in the 19F spectrum are not. The 1H NMR
spectrum at -60 °C shows two sets of peaks for all hydrogen
nuclei indicating the presence of two isomers in an ap-
proximately 3:2 ratio. It seems reasonable that these isomers
are simply due to different conformations of the diene ligand
about the M-diene axis which interconvert only slowly on the
NMR time scale by diene rotation. As the sample is warmed
the isomer ratio remains constant, but the previously sharp peaks
broaden somewhat and there is little change in the chemical
shift of individual peaks, indicating that the broadening is
probably not due to a fluxional process that interconverts the
isomers, such as rotation about the M-diene bond. The 19F
NMR spectrum of 21 at -60 °C also shows the presence of
two isomers in the same 3:2 ratio, but there is no broadening
of the peaks on warming the sample to room temperature and
the isomer ratio remains unchanged. The solution IR spectrum
of 21 does not reflect the presence of two isomers as there is
only one band for the carbonyl group at 1965 cm-1. For 22 the
difference between the 1H NMR spectrum obtained at -60 °C
and that obtained at room temperature is not so marked. Two
isomers can also be observed for 22 by NMR spectroscopy but
the minor one is in barely detectable quantities. In spectra of
We have no specific explanation for this behavior, but
precedents exist. The 1H NMR spectrum of 23 shows the
presence of major and minor compounds which the authors
suggest may be due to geometric isomers.41 A similar NMR
broadening phenomenon has been reported for the NMR spectra
of the closely related complex 24.42 The authors suggested it
may be due to an equilibrium between the complex and a
coordinatively unsaturated derivative, which could be formed
via dissociation of one of the double bonds of the diene ligand.
Also considered as a cause for the broadening was electron
exchange between the complex and a small amount of para-
magnetic oxidation or reduction product.
A single-crystal X-ray structural determination of 22 con-
firmed formation of the substituted cyclopentadiene ligand and
the exo orientation of the perfluoroisopropyl substituent. A ball-
and-stick representation of the structure is shown in Figure 5,
and crystallographic information is presented in Table 1. There
are two crystallographically independent molecules in the unit
cell, one of which shows disorder around the C(10)-C(11) bond.
(40) Smart, B. E. Organofluorine Chemistry; Plenum: New York, 1994.
(41) Green, M. L. H.; Lindsell, W. E. J. Chem. Soc. A 1969, 2215.
(42) Jernakoff, P.; Fox, J. R.; Cooper, N. J. J. Organomet. Chem. 1996,
512, 175.

3284 J. Am. Chem. Soc., Vol. 123, No. 14, 2001
Hughes et al.
The overall architecture of the complex is very similar to that
of 24,42 and as with other reported complexes resulting from
substitution at a cyclopentadienyl ligand, the fluoroalkyl group
is in the exo position.11 As discussed below, complexes 21 and
22 can be viewed as model compounds for an intermediate in
the formation of the hydride complexes 14-17.
Scheme 1
In further contrast to reactions of primary, secondary, and
aryl halides, reaction of 1 molar equiv of the tertiary perfluo-
roalkyl iodide IC(CF3)3 with 4 or 5 does not result in
fluoroalkylation at the metal or at a cyclopentadienyl ring, but
instead reaction occurs at the ethylene ligand to give 25 or 26.
In the 1H NMR spectra of 25 and 26 the substituted alkyl group
gives rise to two multiplets at δ 1.90 and 1.56 ppm (25) and
2.09 and 1.28 ppm (26), which each integrate for two hydrogens.
In the 13C NMR spectrum the tungsten-bound carbon in 26
shows tungsten satellites (JCW ) 60 Hz) as do the cyclopenta-
dienyl carbons (JCW ) 6 Hz). The resonance for the perfluoro-
tert-butyl group in the 19F NMR spectrum of 26 appears as a
quintet. The coupling of 0.8 Hz was barely resolved and is
presumably due to coupling to the hydrogen nuclei on the alkyl
group. In the 19F NMR spectrum of both 24 and 25 the
perfluoro-tert-butyl group gave rise to a broad singlet at δ -66.0
ppm. The X-ray structure of 26 has been reported previously,29
and is very similar to that of other Group 6 bent metallocene
complexes. The W-alkyl σ-bond length (W-C(11)) of 2.279-
(12) Å is very similar to those in [WCp2(CH2C6H3Me2)2]2 of
2.276 and 2.291 Å.43
in bonds from the metal to both carbon and iodine, observations
of 10 and 11 as stable products indicate that the metal-carbon
bond is formed first. We suggest the mechanism shown in
Scheme 1. Initial electron transfer from metal to RFI must be
followed by very rapid decomposition of the radical anion to
•
RF and I-;47 recombination of the 17-electron radical cation
•
with RF then affords the metal fluoroalkyl cations, observed
as stable products in the case of 10 and 11. In the case of
formation of 8 or 9, loss of ethylene from molybdenum must
be facile, allowing coordination of iodide and formation of the
observed products. Notably CO loss from molybdenum must
be considerably less facile than loss of ethylene, as 10 shows
no tendency to lose CO and bind I-. Similarly, the tungsten
ethylene bond must be considerably stronger than the corre-
sponding bond to molybdenum, as 11 is stable to ethylene loss,
even on heating. The relative affinities for CO vs ethylene, and
the greater lability of ethylene in cationic molybdenocene
complexes compared to cationic tungstenocene complexes, is
illustrated by displacement of ethylene from [MoCp2(C2H4)R]+
(R ) H, CH3) by CO in refluxing acetone.44,45 These authors
reported that the reaction of [WCp2(C2H4)H]+ with CO proceeds
much more slowly, and attempts to repeat this reaction in our
laboratory resulted in no observable formation of [WCp2-
(CO)H]+.
If a fluoroalkyl radical were involved in the reaction pathway,
it might be possible to observe other manifestations of its
presence, provided it escaped the solvent cage before recom-
bination at the metal. Fluoroalkyl radicals do not disproportion-
ate to give fluoroalkanes and fluoroalkenes, as do hydrocarbon
analogues, but instead undergo coupling reactions, initiate the
polymerization of alkenes such as norbornene, and are much
more voracious hydrogen atom abstractors than are hydrocarbon
radicals.52,53 Accordingly, the formation of compounds 8-11
was observed in the presence of a large molar excess of
norbornene, with no change in the reaction outcome, and no
observation of polymerization.52 In addition, when reactions
were carried out in toluene-d8 no RFD resulting from abstraction
of benzylic D• by RF• was observed. Similarly, carrying out the
same reactions in the presence of 70 molar equiv of 9,10-
dihydroanthracene as an H-atom donor resulted in no change
in the organometallic products, and no observable RFH. If
fluoroalkyl radicals are indeed formed, they do not escape a
fate other than recombination at the metal center. However, the
less selective reaction of perfluoro-n-butyl iodide with the
At this stage of the discussion, some mechanistic consider-
ations are appropriate. It has been reported that reaction of
[MCp2(C2H4)] (M ) Mo, W) with CH3I gives the cationic
complexes [MCp2(CH3)(C2H4)]I.44,45 In this case the methyl
carbon bears some positive charge and the first step is envisaged
to be nucleophilic attack by the coordinatively saturated metal
center on this carbon to form the metal-carbon bond. However,
the carbon-iodine bond in perfluoroalkyl iodides is oppositely
polarized δ-C-Iδ+, so it is considered unlikely that the first
step in their reactions with any nucleophiles involves nucleo-
philic attack at carbon.8,46 Consequently, reactions of perfluo-
roalkyl iodides with electron-rich species involve either a single
electron-transfer step to afford (RFI)•-, which rapidly generates
RF and I- (such electron transfer/dissociation may indeed be
•
concerted),47 or a nucleophilic attack at I to displace a
fluoroalkyl carbanion.8,46 The latter pathway may be favored
when the fluorinated carbanion is secondary or tertiary, and
therefore considerably stabilized by adjacent CF3 groups.48-51
With these factors in mind, formation of bonds from primary
and benzylic fluoroalkyls to Mo and W in compounds 8-11
cannot be rationalized in terms of the SN2-type mechanism
envisaged for CH3I.44,45 Two-electron attack by the metal on
RFI would be expected at I, not at C, and the metal-iodine
bond would be formed first. While formation of 8 and 9 results
(43) Prout, K.; Jefferson, I. W.; Forder, R. A. Acta Crystallogr. 1975,
B31, 618.
(44) Benfield, F. W. S.; Francis, B. R.; Green, M. L. H. J. Organomet.
Chem. 1972, 44, C13.
(45) Benfield, F. W. S.; Cooper, N. J.; Green, M. L. H. J. Organomet.
Chem. 1974, 76, 49.
(46) Wakselman, C. J. Fluorine Chem. 1992, 59, 367-378.
(47) Andrieux, C. P.; Ge´lis, L.; Medebielle, M.; Pinson, J.; Save´ant, J.-
M. J. Am. Chem. Soc. 1990, 112, 3509-3520.
(48) Dixon, D. A.; Fukunaga, T.; Smart, B. E. J. Am. Chem. Soc. 1986,
108, 4027-4031.
(49) Smart, B. E.; Middleton, W. J.; Farnham, W. B. J. Am. Chem. Soc.
1986, 108, 4905-4908.
(50) Farnham, W. B.; Dixon, D. A.; Calabrese, J. C. J. Am. Chem. Soc.
1988, 110, 2607-2611.
(52) Feiring, A. E. J. Org. Chem. 1985, 50, 3269-3274.
(53) Dolbier, W. R., Jr. Chem. ReV. 1996, 96, 1557-1584.
(51) Farnham, W. B. Chem. ReV. 1996, 96, 1633-1640.

Reactions of Halofluorocarbons with Group 6 Complexes
J. Am. Chem. Soc., Vol. 123, No. 14, 2001 3285
tungsten complex 5, to give many unidentified products as well
as the ring-substituted complex 12, indicates that other reaction
pathways are available to whatever reactive fluoroalkyl inter-
mediate is formed. For example, we have previously observed
metal-centered fluoroalkylation and exo-cyclopentadienyl ring
fluoroalkylation in reactions of primary and secondary perfluo-
roalkyl iodides with cyclopentadienyl-rhodium11 and -cobalt10
complexes, and an identical sequence of steps has been proposed
in tungsten systems.38,41,54
Scheme 2
Since cyclopentadienyl ring fluoroalkyation is observed most
selectively with perfluoroisopropyl iodide, we concentrated our
efforts on this system, although this pathway is also observed
for perfluoroaryl substrates. When carbonyl precursors 6 and 7
are used, the exo-fluoroalkylated products 21 and 22 are formed,
but are inert to further reaction. It seems reasonable that
formation of 14 and 15 occurs via intermediates which are
ethylene analogues of 21 and 22, but that the ethylene ligand is
more labile. Notably the lability of ethylene in these formally
M(II) intermediates must be greater than that in the isolable
W(IV) cation 11. Loss of ethylene generates a vacant coordina-
tion site, into which migrates the endo-hydrogen from the
cyclopentadiene ring, reestablishing the coordinatively saturated
metal center and rearomatizing the cyclopentadienyl ring. We
have previously established this sequence of reactions for exo-
fluoroalkyation of a cyclopentadienyl-rhodium complex to give
an isolable cyclopentadiene compound; subsequent generation
of a vacant site results in endo-H migration to give a cyclo-
pentadienylrhodium hydrido product.55 The stereochemistry of
cyclopentadienyl ring fluoroalkylation is clearly exo in the cases
reported here, but what is the nature of the fluoroalkylating
agent? Closer monitoring of these reactions by NMR spectros-
copy revealed the presence of small amounts (ca. 5%) of
saturated (CF3)2CFH and perfluoropropene, CF3CFdCF2. The
former could arise by H-atom abstraction by the corresponding
radical (CF3)2CF•, but this radical is not known to afford the
fluoroalkene because of its very strong â-CF bonds.53 Observa-
tion of fluoroalkenes is instead a characteristic signature of the
corresponding perfluoroalkyl anion, in this case (CF3)2CF-,
which readily eliminates a â-fluoride.51
and abstraction of D+ from the trapping agent. Consequently,
we interpret the traces of (CF3)2CFH always observed as
resulting from reaction of (CF3)2CF- with adventitious H2O
present in the reaction, and the previous observations of CF3-
CFdCF2 as resulting from fluoride elimination from the same
perfluorocarbanion intermediate. To eliminate the possibility that
the perfluoroalkyl species responsible for formation of the
organometallic product 15 was not that responsible for formation
of (CF3)2CFD, the reaction was carried out with varying
concentrations of CH3OD. The resultant ratio of (CF3)2CFD/
15 versus concentration of CH3OD increases linearly, indicating
that CH3OD and the organometallic precursor to 15 are
competing for the same perfluoroalkyl intermediate, which must
be (CF3)2CF-.
Accordingly, we propose the mechanism outlined in Scheme
2. Initial nucleophilic attack on iodine by the tungsten center
presumably results in formation of the ion pair [MCp2-
(C2H4)I]+ RF-. In an attempt to determine if the perfluorocar-
banion escaped from the solvent cage to react with another
molecule of the cation or it reacted with the tungsten cation
with which it was formed, a series of reactions between 5 and
(CF3)2CFI were performed in which the concentrations were
In an elegantly designed experiment, CH3OD has been used
-
varied. If RF were to escape the solvent cage, at low
-
•
to distinguish between an RF and an RF mechanism for the
decomposition of [Co(Py)(DH)2(CF(CF3)2] by NaBH4 to give
Na[Co(Py)(DH)2] and (CF3)2CFD.56 These results were inter-
preted in terms of formation of RF-, which reacts with the more
concentrations the amount of CF3CFdCF2 formed relative to
15 should increase as elimination of F- would become more
likely than reaction with a more difficult to find [WCp2-
(C2H4)I]+. While the results were clouded by the large amount
of scatter observed for each data point, the amount of F2Cd
CF(CF3) formed remained approximately constant. It seems
probable that the (CF3)2CF- reacts within the ion pair of which
it is initially a part. We note that this mechanism differs from
that proposed for the reaction of 7 with CCl4 to give 24, in
which a single electron transfer was proposed as the first step,
followed by a radical coupling pathway.42
Similar observations were made for the reactions of perfluoro-
tert-butyl iodide with 5 to give 26. NMR monitoring of the
reaction revealed small amounts of (CF3)2CdCF2 in the product
mixture, and trapping experiments using CH3OD produced
(CF3)3CD, not (CF3)3CH; both results are signatures for the
perfluoro-tert-butyl carbanion.51 We did not carry out analogous
trapping experiments or explore further any reactions of
perfluoroaryl substrates.
•
acidic O-D bond in CH3OD, rather than formation of RF ,
which would be expected to react with the weaker C-H bond57
to give RFH. The products (CF3)2CFD and (CF3)2CFH can easily
be distinguished with 19F NMR.58
In a control experiment ICF(CF3)2 was photolyzed in the
presence of CH3OD in a reaction known to afford the fluorinated
radical; the only product detected was (CF3)2CFH resulting from
abstraction of H• from the weaker C-H bond. However, when
the reaction of 5 with (CF3)2CFI was carried out in the presence
of only 1 molar equiv of CH3OD, the yield of organometallic
product 15 was dramatically reduced and (CF3)2CFD now made
up approximately 45% of the fluorine-containing products, along
with the same traces of (CF3)2CFH observed in the absence of
CH3OD. This is only consistent with the formation of (CF3)2CF-
(54) Forschner, T. C.; Cooper, N. J. J. Am. Chem. Soc. 1989, 111, 7420.
(55) Hughes, R. P.; Husebo, T. L.; Maddock, S. M.; Rheingold, A. L.;
Guzei, I. A. J. Am. Chem. Soc. 1997, 119, 10231-10232.
(56) Toscano, P. J.; Brand, H.; Liu, S.; Zubieta, J. Inorg. Chem. 1990,
29, 2101-2105.
(57) Kerr, J. A. Chem. ReV. 1966, 66, 465.
(58) Andreades, S. J. Am. Chem. Soc. 1964, 86, 2003-2010.
Given a mechanism in which a fluoroalkyl carbanion and
[WCp2(C2H4)I]+ are formed initially, and the carbanion is
trapped by CH3OD, the amount of fluoroalkyated organometallic
product produced decreases. What is the fate of the other
intermediate [WCp2(C2H4)I]+ and the methoxide anion that must

3286 J. Am. Chem. Soc., Vol. 123, No. 14, 2001
Hughes et al.
also be formed? In each of the systems investigated, as the
amount of added methanol was increased, a light orange
precipitate, which could not be characterized, was formed, along
with a green solution from which the 2-methoxyethyl complex
27 was isolated. This compound has similar spectroscopic
properties to those of its crystallographically characterized
analogue 2629 (see above). The 2-methoxyethyl group gives rise
to multiplets in the 1H NMR spectrum at δ 1.35 and 3.33 ppm
for the methylene protons and a singlet at δ 3.26 ppm for the
methoxy group. The resonance for the metal-bound carbon
shows tungsten satellites (JCW ) 28 Hz) in the 13C NMR
spectrum. Complex 27 is not thermally stable and undergoes
complete decomposition when stored overnight at room tem-
perature under nitrogen. An X-ray structure of 27 was obtained
which confirms the overall molecular connectivity, but was not
of sufficient quality for accurate distances and angles to be
obtained. Formation of 27 can be rationalized by nucleophilic
attack by methoxide on the ethylene ligand of the putative
intermediate [WCp2(C2H4)I]+.
However, such reaction selectivity raises the issue of why
the (CF3)2CF- nucleophile reacts at cyclopentadienyl and not
at ethylene. The Davies-Green-Mingos rules predict kineti-
cally controlled attack by nucleophiles at the ethylene ligand
of [WCp2(C2H4)I]+ rather than the cyclopentadienyl ligand, and
this is apparently observed in the formation of 27.59 However,
examples of multiple site attack by nucleophiles are not
uncommon, and the kinetic site of attack is not always the one
actually observed.63-65 One possibility that we considered was
that the reaction of (CF3)2CF- does indeed occur with kinetic
selectivity for attack at ethylene, as observed for methoxide,
but that the reaction of (CF3)2CF- is reversible, with the eventual
outcome being the result of thermodynamically controlled attack
at cyclopentadienyl. This is discounted by the observation that
the more stable perfluoro-tert-butyl carbanion (CF3)3C- reacts
at ethylene, but shows no signs of reversibility and subsequent
attack at cyclopentadienyl. There could be some steric factor
that disfavors the product of (CF3)3C- attack at cyclopentadienyl
and results in a switching of thermodynamic product stabilities,
but without further evidence that this is a straw worth grasping,
the origins of differing selectivities in the case of (CF3)2CF-
(and presumably C6F5-) compared to (CF3)3C- remain a
mystery.
metal center represent the first reported examples of fluoroalkyl
complexes of Mo(IV) and W(IV).
Experimental Section
General Considerations. All reactions were performed in oven-
dried glassware, using standard Schlenk techniques, under an atmo-
sphere of dinitrogen that had been deoxygenated over BASF catalyst
and dried over Aquasorb, or in a Braun Drybox. THF was distilled
under nitrogen from potassium and benzophenone ketyl and benzene
was distilled from sodium immediately before use. Dichloromethane
and hexane were refluxed over calcium hydride under nitrogen and
distilled immediately before use. IR spectra were recorded on a Perkin-
Elmer FTIR 1600 Series spectrometer. NMR spectra were recorded
1
on a Varian Unity Plus 300 FT spectrometer. H NMR spectra were
referenced to the protio impurity present in the solvent: C6D6 (δ 7.16
ppm), CDCl3 (δ 7.27 ppm), CD3CN (δ 1.94 ppm). 19F NMR spectra
were referenced to CFCl3 (0.00 ppm). 13C NMR spectra were referenced
to CD2Cl2 (δ 53.8 ppm). Microanalyses were performed by Schwarz-
kopf Microanalytical Laboratory, Woodside, NY. I(CF2)3CF3 (Aldrich),
ICF2C6F5 (PCR), ICF(CF3)2 (PCR), and IC6F5 (Aldrich) were purified
by washing with a solution of sodium thiosulfate to remove iodine,
followed by washing with water and then drying over magnesium
sulfate and deoxygenation by several freeze-evacuate-thaw cycles.
BrC6F5 (Oakwood) was deoxygenated and used as received. IC(CF3)3
(PCR) was dissolved in deoxygenated benzene and used as received.
CH3OD (Aldrich) was used as received. [MoCp2(C2H4)] (4),60 [WCp2-
(C2H4)] (5),60 [MoCp2(CO)] (6),61 and [WCp2(CO)] (7)62 were prepared
according to literature procedures.
Mo(η5-C5H5)2[(CF2)3CF3]I (8). MoCp2(C2H4) (0.030 g, 0.118 mmol)
was dissolved in tetrahydrofuran (4 mL). I(CF2)3CF3 (0.021 mL, 0.122
mmol) was added to give a brown solution. The reaction mixture was
stirred for 10 min, then filtered under nitrogen, and the solvent removed
in vacuo. The light brown solid was recrystallized from dichlo-
romethane/ethanol then dichloromethane/hexane (0.032 g, 47%).
Crystals suitable for an X-ray study were grown from dichloro-
1
methane/hexane. Mp: 170-172 °C. H NMR (C6D6) δ 4.56 (s, 10H,
C5H5). 19F NMR (C6D6) δ -61.0 (m, 2F, R-CF2), -80.8 (tt, J FF ) 10
Hz, J ) 4 Hz, 3F, CF3), -109.3 (m, 2F, â-CF2), -124.7 (m, 2F,
FF
γ-CF2). Anal. Calcd for C14H10F9IMo (572.02): C, 29.39; H, 1.76.
Found: C, 29.39; H, 1.55.
Mo(η5-C5H5)2(CF2C6F5)I (9). MoCp2(C2H4) (0.100 g, 0.393 mmol)
was dissolved in tetrahydrofuran (12 mL). ICF2C6F5 (0.07 mL, 0.41
mmol) was added dropwise to give a brownish solution that was stirred
at room temperature for half an hour. The solution was filtered under
nitrogen, the solvent volume was reduced to approximately 1 mL, and
hexane (5 mL) was added to complete precipitation of the product.
The green solid was washed with hexane (2 × 5 mL) and dried in
Conclusions
1
vacuo (0.115 g, 51%). Mp: decomposition at ca. 120 °C. H NMR
4
(CD3CN) δ 5.45 (s, 10H, C5H5). 19F NMR (CD3CN) δ -40.8 (t, JFF
Oxidative addition reactions of perfluoroalkyl iodides with
Mo(II) and W(II) precursors afford M(IV) products resulting
from fluoroalkylation at the metal, at the cyclopentadienyl ring,
or at ethylene ligands. In the case of primary or benzylic
substrates, attempts to trap or provide other evidence for
intermediate fluorinated radicals or carbanions have been
unsuccessful, whereas with secondary and tertiary substrates
positive evidence for fluorinated carbanion intermediates has
been obtained. The reasons for differing selectivities for
reactions of these intermediate fluoroalkylating agents remain
a matter of conjecture. The products of fluoroalkylation at the
3
) 29 Hz, 2F, CF2), -136.7 (m, 2F, C6F5 ortho), -158.7 (tm, JFF
)
19 Hz, 1F, C6F5 para), -163.6 (m, 2F, C6F5 meta). Anal. Calcd for
C17H10F7IMo (570.10): C, 35.82; H, 1.77. Found: C, 35.85; H, 1.88.
[Mo(η5-C5H5)2(CF2C6F5)(CO)]I (10). MoCp2(CO) (0.040 g, 0.157
mmol) was dissolved in benzene (4 mL) and ICF2C6F5 (0.03 mL, 0.17
mmol) was added. A pale yellow precipitate formed immediately. This
was collected by filtration and washed with benzene (5 mL) and hexane
(2 × 5 mL) to give analytically pure product (0.075 g, 82%). Mp:
decomposition at ca. 190 °C. IR (Nujol) υCO 2037 cm-1. 1H NMR (CD3-
4
CN): δ 5.91 (s, 10H, C5H5). 19F NMR (CD3CN): δ -29.1 (t, JFF
)
28 Hz, 2F, CF2), -138.4 (m, 2F, C6F5 ortho), -154.4 (t, 3JFF ) 20 Hz,
1F, C6F5 para), -160.8 (m, 2F, C6F5 meta). Anal. Calcd for C18H10F7-
IMoO (582.11): C, 36.15; H, 1.69. Found: C, 36.33; H, 1.73.
[W(η5-C5H5)2(CF2C6F5)(C2H4)]I (11). WCp2(C2H4) (0.140 g, 0.041
mmol) was dissolved in THF (10 mL). ICF2C6F5 (0.075 mL, 0.436
mmol) was added dropwise and an off-white precipitate formed. The
reaction mixture was stirred for 15 min. The solvent was removed by
filtration and the product was washed with hexane (2 × 5 mL) and
filtered to give analytically pure product (0.200 g, 77%). Mp: 114-
116 °C. 1H NMR (CD3CN): δ 5.79 (s, 10H, C5H5), 2.81 (m, 2H, CH2d
CH2), 2.56 (m, 2H, CH2dCH2). 19F NMR (CD3CN): δ -30.8 (t, W
(59) Davies, S. G.; Green, M. L. H.; Mingos, D. M. P. Tetrahedron 1978,
34, 3047.
(60) Benfield, F. W. S.; Green, M. L. H. J. Chem. Soc., Dalton Trans.
1974, 1324.
(61) Geoffroy, G. L.; Bradley, M. G. Inorg. Chem. 1978, 17, 2410.
(62) Francis, B. R.; Green, M. L. H.; Luong-thi, T.; Moser, G. A. J.
Chem. Soc., Dalton Trans. 1976, 1339.
(63) Semmelhack, M. F. Ann. N.Y. Acad. Sci. 1977, 333, 36.
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Organometallics 1986, 5, 158.

Reactions of Halofluorocarbons with Group 6 Complexes
J. Am. Chem. Soc., Vol. 123, No. 14, 2001 3287
satellites, 4JFF ) 33 Hz, JFW ) 26 Hz, 2F, CF2), -135.9 (m, 2F, C6F5,
ortho), -154.5 (t, 3JFF ) 21 Hz, 1F, C6F5, para), -160.9 (m, 2F, C6F5,
meta). Anal. Calcd for C19H14F7IW (686.07): C, 33.26; H, 2.06.
Found: C, 33.44; H, 1.94.
at room temperature for 30 min then filtered under nitrogen. The solvent
was removed in vacuo and the residue was washed with hexane (2 ×
5 mL) and recrystallized from benzene/hexane (0.051 g, 49%). Mp:
1
decomposition at ca. 114 °C. IR (Nujol mull): υWH 1938 cm-1. H
W(η5-C5H5)[C5H4((CF2)3CF3)]HI (12). WCp2(C2H4) (0.050 g, 0.146
mmol) was dissolved in benzene (6 mL) and I(CF2)3CF3 (0.028 mL,
0.163 mmol) was added. The resulting brown solution was stirred for
15 min and then filtered. The solvent was removed from the filtrate
giving a brown residue. This residue contained impure 12. Attempts
to recrystallize the product resulted in partial conversion to 13. 1H NMR
(C6D6): δ 4.79 (m, 1H, C5H4), 4.57 (m, 1H, C5H4), 4.46 (s, 5H, C5H5),
4.05 (br s, 1H, C5H4), 3.75 (br s, 1H, C5H4), -10.92 (s, W satellites,
JHW ) 63.0 Hz, 1H, W-H). 19F NMR (C6D6): δ -81.4 (tt, 3JFF ) 3.0
Hz, 4JFF ) 10 Hz, 3F, CF3), -101.5 (dm, 2JFF ) 275 Hz, 1H, R-CF2),
NMR (300 MHz, C6H6): δ 5.24 (m, 1H, C5H4), 5.01 (m, 1H, C5H4),
4.38 (s, 5H, C5H5), 4.21 (m, 1H, C5H4), 3.70 (m, 1H, C5H4), -11.64
(s, W satellites, JHW ) 56.4 Hz, 1H, W-H). 19F NMR (282 MHz,
C6H6): δ -141.3 (dd, JFF ) 22 Hz, JFF ) 7 Hz, 2F, C6F5 ortho), -158.6
(t, JFF ) 22 Hz, 1F, C6F5 para), -163.4 (m, 2F, C6F5 meta). Anal.
Calcd for C16H10F5IW (608.00): C, 31.61; H, 1.66. Found: C, 31.53;
H, 1.89.
W(η5-C5H5)[C5H4(C6F5)]HBr (17). WCp2(C2H4) (0.150 g, 0.438
mmol) was dissolved in THF (6 mL). On addition of BrC6F5 (0.056
mL, 0.441 mmol) the orange solution turned brown/yellow. It was
stirred for 1 h at room temperature then filtered under nitrogen.
Reduction of the solvent volume gave a brown solid that was washed
with hexane then recrystallized from dichloromethane/hexane (0.159
g, 65%). Mp: decomposition at ca. 100 °C. IR (Nujol mull): υWH 1895
2
-108.0 (dm, JFF ) 275 Hz, 1H, R-CF2), -122.7 (m, 2F, â-CF2),
-125.5 (m, 2F, γ-CF2).
W(η5-C5H5)[C5H4((CF2)3CF3)]I2 (13). WCp2(C2H4) (0.150 g, 0.438
mmol) was dissolved in benzene (6 mL) and I(CF2)3CF3 (0.075 mL
0.442 mmol) was added giving a brown solution. This was filtered
and the benzene removed in vacuo. Dichloromethane (10 mL) and
iodoform (0.861 g, 2.19 mmol) were added to the residue. The solution
was stirred for 4 h during which time it turned dark green. Filtration
followed by removal of all the solvent gave a dark green/brown product.
This was dissolved in a minimum of dichloromethane and filtered to
remove iodoform. The filtrate was placed on a silica gel column (6 ×
1.5 cm) and eluted with dichloromethane. The first dark yellow/brown
fraction contained excess CHI3 and was discarded. The second dark
green fraction was collected, the solvent volume was reduced under
reduced pressure, and hexane was added giving a dark green precipitate
that was recrystallized from dichloromethane/hexane (0.050 g, 15%).
Mp: 220-223 °C. 1H NMR (CDCl3): δ 5.91 (m, 3JHH ) 2.7 Hz, 4JHH
) 8.8 Hz, 4JHH ) 2.6 Hz, 4JHF ) 1.0 Hz, 2H, C5H4), 5.70 (s, 5H, C5H5),
1
cm-1. H NMR (300 MHz, C6D6): δ 5.20 (m, 1H, C5H4), 5.03 (m,
1H, C5H4), 4.39 (s, 6H, C5H5, C5H4), 4.30 (m, 1H, C5H4), -11.18 (s,
W satellites, JHW ) 57.6 Hz, 1H, W-H). 19F NMR (282 MHz, C6D6):
δ -141.4 (dd, JFF ) 23 Hz, JFF ) 6 Hz, 2F, C6F5 ortho), -158.9 (t,
JFF ) 23 Hz, 1F, C6F5 para), -163.5 (m, 2F, C6F5). Anal. Calcd for
C16H10BrF5W (561.00): C, 34.26; H, 1.80. Found: C, 34.40; H, 1.70.
W(η5-C5H5)[C5H4(CF(CF3)2)]I2 (18). W(η5-C5H5)[C5H4(CF(CF3)2)]-
HI (15) (0.027 g, 0.044 mmol) was dissolved in dichloromethane (3
mL) and iodoform (0.017 g, 0.046 mmol) was added. The solution
was stirred at room temperature for 3 h during which time it turned
green. Filtration in the open followed by reduction of the solvent volume
and addition of hexane afforded green microcrystals. The product was
recrystallized from dichloromethane/hexane (0.018 g, 55%). Crystals
suitable for diffraction were grown from dichloromethane/hexane.
Mp: 211-212 °C. 1H NMR (300 MHz, CDCl3): δ 5.95 (m, 2H, C5H4),
5.67 (s, 5H, C5H5), 5.20 (t, JHH ) 2.5 Hz, 2H, C5H4). 19F NMR (282
3
5.27 (t, JHH ) 2.7 Hz, 2H, C5H4). 19F NMR (CDCl3): δ -81.4 (m,
3F, CF3), -108.0 (m, 2F, R-CF2), -122.8 (m, 2F, â-CF2), -125.8 (m,
2F, γ-CF2). Anal. Calcd for C14H9F9I2W (785.87): C, 21.40; H, 1.15.
Found: C, 21.31; H, 1.19.
3
3
MHz, CDCl3): δ -74.4 (d, JFF ) 9 Hz, 6F, CF3), -176.2 (sept, JFF
) 10 Hz, 1F, CF). Anal. Calcd for C13H9F7I2W (735.86): C, 21.22; H,
1.23. Found: C, 21.17; H, 0.96.
Mo(η5-C5H5)[C5H4(CF(CF3)2)]HI (14). MoCp2(C2H4) (0.040 g,
0.157 mmol) was dissolved in benzene (3 mL) and ICF(CF3)2 (0.022
mL, 0.157 mmol) was added. The solution was stirred for 30 min and
filtered and the solvent was removed in vacuo. The brown residue was
dissolved in benzene, the volume was reduced to ca. 1 mL, and a similar
volume of hexane was added to precipitate the product. It was
recrystallized from benzene/hexane (0.037 g, 45%). Mp: decomposition
at ca. 55 °C. IR (C6H6): υMoH 1958 cm-1. 1H NMR (300 MHz, C6D6):
W(η5-C5H5)[C5H4(C6F5)]I2 (19). W(C5H5)[C5H4(C6F5)]HI (16) (0.075
g, 0.123 mmol) was dissolved in dichloromethane (5 mL) in the open.
Iodoform (0.486 g, 1.23 mmol) was added and the solution was stirred
for 1 h during which time it turned green. Filtration followed by
reduction of the solvent volume under reduced pressure and addition
of hexane gave a green crystalline product that was recrystallized from
dichloromethane/hexane and washed well with ethanol then hexane
(0.069 g, 76%). Mp: decomposition at ca. 210 °C with apparent loss
of I2. 1H NMR (300 MHz, CDCl3): δ 5.91 (t, JHH ) 2.7 Hz, 2H, C5H4),
5.58 (m, 2H, C5H4), 5.55 (s, 5H, C5H5). 19F NMR (282 MHz, CDCl3):
δ -139.0 (d, JFF ) 16 Hz, 2F, C6F5 ortho), -154.2 (t, JFF ) 21 Hz,
1F, C6F5 para), -161.9 (m, 2F, C6F5 meta). Anal. Calcd for C16H9F5I2W
(733.90): C, 26.19; H, 1.24. Found: C, 25.81; H, 1.25.
3
4
4
δ 4.78 (m, JHH ) 3.1 Hz, JHH ) 2.5 Hz, JHH ) 2.9 Hz, 1H, C5H4),
4.52 (s, 5H, C5H5), 4.43 (br s, 1H, C5H4), 4.29 (m, 4JHH ) 2.5 Hz, 4JHH
3
4
) 0.5 Hz, J
) 2.7 Hz, JHF ) 2.4 Hz, 1H, C5H4), 4.03 (br s, 1H,
HH
C5H4), -7.82 (s, 1H, Mo-H). 19F NMR (282 MHz, C6D6): δ -74.1
3
4
3
(dq, JFF ) 10 Hz, JFF ) 10 Hz, 3F, CF3), -75.4 (dq, JFF ) 10 Hz,
4J FF ) 10 Hz, 3F, CF3), -171.2 (sept d, 3J FF ) 10 Hz, 3JFF ) 10 Hz,
4JFH ) 2 Hz, 1F, CF). Anal. Calcd for C13H10F7IMo (522.06): C, 29.90;
H, 1.93. Found: C, 29.66; H, 1.85.
W(η5-C5H5)[C5H4(C6F5)]Br2 (20). WCp[C5H4(C6F5)]HBr (17) (0.100
g, 0.178 mmol) was dissolved in dichloromethane (3 mL) and
bromoform (0.301 g, 1.19 mmol) was added. The solution was stirred
for 3 h during which time it turned green and a small amount of dark
precipitate appeared. It was filtered in the open, the volume of the
solvent was reduced, and hexane was added to precipitate the product,
which was recrystallized from dichloromethane/hexane (0.072 g, 63%).
W(η5-C5H5)[C5H4(CF(CF3)2)]HI (15). WCp2(C2H4) (0.275 g, 0.804
mmol) was dissolved in THF (10 mL) and ICF(CF3)2 (0.121 mL, 0.859
mmol) was added dropwise. The solution was stirred at room
temperature for 30 min during which time the color changed to purple/
brown. The solution was filtered under nitrogen and the solvent was
removed in vacuo. The purple residue was washed twice with hexane
(2 × 5 mL) (0.434 g, 86%). Crystals suitable for X-ray diffraction
were grown from benzene. Mp: 95-98 °C. IR (Nujol mull): υWH 1935
1
Mp: decomposition at ca. 214 °C. H NMR (300 MHz, CDCl3): δ
5.94 (br s, 2H, C5H4), 5.62 (br s, 7H, C5H5, C5H4). 19F NMR (282
MHz, CDCl3): δ -138.8 (d, JFF ) 18 Hz, 2F, C6F5 ortho), -154.2 (t,
JFF ) 22 Hz, 1F, C6F5 para), -161.9 (m, 2F, C6F5 meta). Anal. Calcd
for C16H9Br2F5W (639.90): C, 30.30; H, 1.42. Found: C, 30.16; H,
1.48.
1
3
4
cm-1. H NMR (300 MHz, C6D6) δ 4.77 (m, JHH ) 3.4 Hz, JHH
)
4
2.0 Hz, JHH ) 3.3 Hz, 1H, C5H4), 4.46 (s, 6H, C5H5, C5H4), 3.89 (br
s, 1H, C5H4) 3.82 (br s, 1H, C5H4), -10.93 (s, W satellites, JHW
)
60.0 Hz, 1H, W-H). 19F NMR (282 MHz, C6D6): δ -73.5 (dq, JFF
) 10 Hz, 4JFF ) 10 Hz, 3F, CF3), -75.7 (dq, 3JFF ) 10 Hz, 4JFF ) 10
Hz, 3F, CF3), -171.7 (sept d, 3JFF ) 10 Hz, 3JFF ) 10 Hz, 4JHF ) 1.0
Hz, 1F, CF). Anal. Calcd for C13H10F7IW (609.97): C, 25.60; H, 1.65.
Found: C, 25.35; H, 1.79.
3
Mo(η5-C5H5)[C5H5(CF(CF3)2)]I(CO) (21). MoCp2(CO) (0.051 g,
0.201 mmol) was dissolved in tetrahydrofuran (4 mL) and ICF(CF3)2
(0.030 mL, 0.219 mmol) was added giving a red/brown solution. This
mixture was stirred for 10 min then the solvent was removed in vacuo.
The orange residue was extracted with dichloromethane and filtered
in the open. Reduction of the solvent volume and addition of hexane
afforded an orange powder that was recrystallized from dichlo-
romethane/hexane (0.079 g, 71.6%). Mp: 112-113 °C. IR (Nujol
W(η5-C5H5)[C5H4(C6F5)]HI (16). WCp2(C2H4) (0.058 g, 0.170
mmol) was dissolved in THF (7 mL) and IC6F5 (0.023 mL, 0.170 mmol)
was added resulting in a yellow/brown solution. This mixture was stirred

3288 J. Am. Chem. Soc., Vol. 123, No. 14, 2001
Hughes et al.
1
2
mull): υCO 1952 cm-1. H NMR (300 MHz, C6D5CD3; -60 °C): δ
C5H5), 61.5 (dec, JCF ) 25 Hz, CCF3), 39.7 (s, CH2), -20.8 (s, W
satellites, JCW ) 60 Hz, W-CH2). 19F NMR (282 MHz, C6D6): δ -66.0
(quintet, 9F, CF3). Anal. Calcd for C16H14F9IW (688.93): C, 27.93; H,
2.05. Found: C, 28.10; H, 2.01.
5.30 (m, 1H, C5H5), 4.21 (br s, 1H, C5H5), 4.09 (s, 5H, C5H5), 4.01 (d,
3JHF ) 24.9 Hz, 1H, H-endo), 3.89 (m, 1H, C5H5), 1.90 (m, 1H, C5H5)
(major isomer); 5.02 (br s, 1H, C5H5), 4.95 (m, 1H, C5H5), 4.36 (s,
5H, C5H5), 3.73 (br s, 1H, C5H5), 3.08 (d, 3JHF ) 23.4 Hz, 1H, H-endo),
1.60 (br s, 1H, C5H5) (minor isomer). 19F NMR (282 MHz, C6D5CD3;
-60 °C): δ -73.7 (br s, 6F, CF3), -191.2 (m, 3JFF ) 8 Hz, 3JFH ) 24
Hz, 1F, CF) (major isomer); -73.2 (dq, 3JFF ) 8 Hz, 4JFF ) 8 Hz, 3F,
CF3), -73.9 (dq, 3JFF ) 8 Hz, 4JFF ) 8 Hz, 3F, CF3), -189.0 (m, 3JFF
W(η5-C5H5)2[CH2CH2OCH3]I (27). WCp2(C2H4) (0.050 g, 0.146
mmol) was dissolved in benzene (5 mL) and methanol (0.057 mL, 1.41
mmol) was added followed by ICF(CF3)2 (0.021 mL, 0.149 mmol). A
light orange precipitate and a green/brown solution resulted. The
solution was stirred for 15 min and then filtered to remove the
precipitate. The solvent was removed in vacuo and the residue was
washed with hexane. Recrystallization from dichloromethane/hexane
3
) 8 Hz, JFH ) 24 Hz, 1F, CF) (minor isomer). Anal. Calcd for
C14H10F7IMoO (550.07): C, 30.57; H, 1.83. Found: C, 30.77; H, 1.97.
W(η5-C5H5)[C5H5(CF(CF3)2)]I(CO) (22). WCp2(CO) (0.060 g,
0.175 mmol) was dissolved in tetrahydrofuran (4 mL) and ICF(CF3)2
(0.025 g, 0.177 mmol) was added giving a yellow/brown solution. This
mixture was stirred for 10 min then filtered in the open. The solvent
was removed and the residue was extracted with benzene. On slow
reduction of the solvent volume a small amount of dark precipitate
appeared. This was removed by filtration and the volume of the resulting
orange solution was reduced further and hexane was added to precipitate
the product. Recrystallization from dichloromethane/hexane gave orange
crystals (0.070 g, 63%). Crystals suitable for X-ray diffraction were
grown from toluene/hexane. Mp: 135-137 °C. IR (Nujol mull): υCO
1
gave a dull green powder (0.022 g, 30%). H NMR (300 MHz, CD2-
Cl2):; δ 5.02 (s, 10H, C5H5), 3.33 (m, 2H, CH2), 3.26 (s, 3H, OCH3),
1.35 (m, 2H, CH2). 13C NMR (75 MHz, CD2Cl2): δ 88.5 (s, W satellites,
JCW ) 6 Hz, Cp), 84.5 (s, CH2), 57.2 (s, CH3), -11.3 (s, W satellites,
JCW ) 58 Hz, W-CH2). Anal. Calcd for C13H17IOW (500.03): C,
31.23: H, 3.43.
Crystallographic Structural Determinations. Crystal, data col-
lection, and refinement parameters are collected in Table 1. The
systematic absences in the diffraction data were consistent for the
reported space groups. For 10, 13, and 18 either of the monoclinic
space groups Cc and C2/c was indicated; the noncentrosymmetric group
Cc was chosen for 10 and the centrosymmetric space group C2/c was
chosen for 13 and 18 to yield the chemically reasonable and compu-
tationally stable results of refinement. The structures were solved by
using direct methods, completed by subsequent difference Fourier
syntheses and refined by full-matrix least-squares procedures. Absorp-
tion corrections were not required for structures 10 and 13 because the
variation in the ψ-scan intensities was less than 10%. Empirical
corrections for absorption (DIFABS) were applied to the data for 18
and 22. In 8, atoms F(3), F(5), F(6), and F(7) are disordered over two
positions with an occupancy distribution 70/30 for atom F(3) and 60/
40 for the other fluorine atoms. In 22 the asymmetric unit contains
two crystallographically independent, but chemically similar, molecules.
In one of the two molecules, disorder is found in the CF(CF3)2 group
and two sites of approximately equal occupancy were refined. All non-
hydrogen atoms were refined with anisotropic displacement coefficients,
except for atoms of the disordered group in 22. Hydrogen atoms were
treated as idealized contributions. All software and sources of the
scattering factors are contained in the SHELXTL (5.10) program library.
1943 cm-1. H NMR (300 MHz, C6D5CD3; -60 °C): δ 5.15 (s, 1H,
1
C5H5), 4.28 (d, 3JHF ) 25.1 Hz, 1H, H-endo), 4.03 (s, 5H, C5H5), 3.74
(s, 1H, C5H5), 3.66 (m, 1H, C5H5), 1.74 (s, 1H, C5H5). 19F NMR (282
MHz, C6D5CD3; -60 °C): δ -73.4 (d, 3JFF ) 7.0 Hz, 6F, CF3), -189.2
(m, 3JFF ) 7 Hz, 3JFH ) 25 Hz, 1F, CF). Anal. Calcd for C14H10F7IOW
(637.98): C, 26.36; H, 1.58. Found: C, 26.46; H, 1.55.
Mo(η5-C5H5)2[CH2CH2C(CF3)3]I (25). MoCp2(C2H4) (0.039 g,
0.153 mmol) was dissolved in tetrahydrofuran (4 mL) and a solution
of IC(CF3)3 (0.190 mL, 0.157 mmol) in benzene was added. The orange/
brown solution turned brown and was stirred for half an hour. Removal
of the solvent volume gave the crude product as a light brown solid.
Recrystallization from dichloromethane/hexane gave the pure product
(0.050 g, 54%). Mp: decomposition at ca. 160 °C. 1H NMR (300 MHz,
C6D6): δ 4.28 (s, 10H, C5H5), 1.90 (m, 2H, CH2), 1.56 (m, 2H, CH2).
13C{1H}NMR (75 MHz, CD2Cl2): δ 122.5 (q, JCF ) 288 Hz, CF3),
92.7 (s, C5H5), 60.9 (dec, 2JCF ) 25 Hz, CCF3), 36.7 (s, CH2), -5.7 (s,
Mo-CH2). 19F NMR (282 MHz, C6D6): δ -66.0 (br s, 9F, CF3). Anal.
Calcd for C16H14F9IMo (600.12): C, 32.02; H, 2.35. Found: C, 32.00;
H, 2.39.
W(η5-C5H5)2[CH2CH2C(CF3)3]I (26). WCp2(C2H4) (0.030 g, 0.088
mmol) was dissolved in tetrahydrofuran (4 mL) and a solution of IC-
(CF3)3 in benzene (0.11 mL, 0.09 mmol) was added dropwise giving a
green solution. The reaction mixture was stirred for 15 min then the
solvent was removed in vacuo giving the crude product. The green
residue was dissolved in dichloromethane and filtered. Reduction of
the solvent volume and addition of hexane gave a green crystalline
product (0.041 g, 60%). Crystals suitable for X-ray diffraction were
grown from dichloromethane/hexane. Mp: decomposition at ca. 200
Acknowledgment. R.P.H. is grateful to the National Science
Foundation and to the Petroleum Research Fund, administered
by the American Chemical Society, for generous financial
support.
Supporting Information Available: Atomic fractional
coordinates, bond distances and angles, and anisotropic thermal
parameters for 8, 10, 13, 18, 22, and 27 (PDF). This material is
available free of charge via the Internet at http://pubs.acs.org.
1
°C. H NMR (300 MHz, CD2Cl2): δ 5.03 (s, 10H, C5H5), 2.09 (m,
2H, CH2), 1.28 (m, 2H, CH2). 13C{1H}NMR (75 MHz, CD2Cl2): δ
122.5 (qm, JCF ) 288 Hz, CF3), 88.9 (s, W satellites, JCW ) 6 Hz,
JA003339U