Syntheses and Reactivity of Functionalized (η 5-Tetramethylcyclopentadienyl) Rhenium Complexes

Article abstract of DOI:10.1021/om030443m

The fulvene complexes (η⁶-C₅Me₄CH ₂Re(CO)₂R (1, R = C₆F₅; 2, R = I) react at the exocyclic methylene carbon with allylmagnesium chloride or 2-thienyllithium to yield the anionic species [(η⁵-C ₅Me₄CH₂L)Re(CO)₂R]^- (L = -CH₂CH=CH₂, -2-C₄H₃S). Further reaction with CH₃I at room temperature affords the methyl complexes (η⁵-C₅Me₄CH₂L)Re(CO) ₂(R)(Me) (3, R = C₆F₅; 4, R = I). Protonation of the anionic species with HCl at low temperature gives the hydride complexes trans-(η⁵-C₅Me₄CH₂L)Re(CO) ₂(R)(H) (5, R = C₆F₅; 6, R = I). Thermolysis of hexane solutions of 6, under CO atmosphere, produces the tricarbonyl complexes (η⁵-C₅Me₄CH ₂L)Re(CO)₃ (7) in moderate yields; if the reaction is carried out in the presence of PMe₃, the analogous dicarbonyl phosphine derivatives (η⁵-C₅Me₄CH ₂L)Re(CO)₂(PMe₃) (9) are obtained, but no coordination of the lateral functionality is observed. In clear contrast, thermolysis of hexane solutions of the pentafluorophenyl hydride complexes trans-(η⁵-C₅Me₄CH₂L)Re(CO) ₂(C₆F₅(H), even under CO atmosphere, yields the chelated complexes (η⁵:η^x-C₅Me ₄CH₂L)Re(CO)₂ (8a, L = -CH ₂CH=CH₂, x = 2; 8b, L = -2-C₄H₃S, x = 1). However, prolonged thermal treatment of 8b under a CO atmosphere affords the corresponding tricarbonyl complex 7b. The molecular structures of 8a and 9b have been determined. Both molecules exhibit formal three-legged piano-stool structures, with three terminal ligands in 9b (two CO and one PMe₃), but in the case of 8a, in addition to the two CO's, the third position corresponds to the η²-coordination of the butenyl substituent of the η⁵-C₅Me₄ ring. Attempts to displace the coordinated sidearm in complex 8a have been investigated, as well as the photochemical reactions of tricarbonyl complexes 7.

Full text of DOI:10.1021/om030443m

Organometallics 2003, 22, 4861-4868
4861
Syn th eses a n d Rea ctivity of F u n ction a lized
(η5-Tetr a m eth ylcyclop en ta d ien yl) Rh en iu m Com p lexes:
Molecu la r Str u ctu r es of
(η5:η2-C5Me4CH2CH2CHdCH2)Re(CO)2 a n d
(η5-C5Me4CH2-2-C4H3S)Re(CO)2(P Me3)
Fernando Godoy,† A. Hugo Klahn,*,† Fernando J . Lahoz,‡ Ana I. Balana,‡
Beatriz Oelckers,† and Luis A. Oro‡
Instituto de Qu´ımica, Universidad Cato´lica de Valparaiso, Casilla 4059, Valparaı´so, Chile,
and Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, Zaragoza-50009, Spain
Received J une 9, 2003
The fulvene complexes (η6-C5Me4CH2)Re(CO)2R (1, R ) C6F5; 2, R ) I) react at the exocyclic
methylene carbon with allylmagnesium chloride or 2-thienyllithium to yield the anionic
species [(η5-C5Me4CH2L)Re(CO)2R]- (L ) -CH2CHdCH2, -2-C4H3S). Further reaction with
CH3I at room temperature affords the methyl complexes (η5-C5Me4CH2L)Re(CO)2(R)(Me)
(3, R ) C6F5; 4, R ) I). Protonation of the anionic species with HCl at low temperature
gives the hydride complexes trans-(η5-C5Me4CH2L)Re(CO)2(R)(H) (5, R ) C6F5; 6, R ) I).
Thermolysis of hexane solutions of 6, under CO atmosphere, produces the tricarbonyl
complexes (η5-C5Me4CH2L)Re(CO)3 (7) in moderate yields; if the reaction is carried out in
the presence of PMe3, the analogous dicarbonyl phosphine derivatives (η5-C5Me4CH2L)Re-
(CO)2(PMe3) (9) are obtained, but no coordination of the lateral functionality is observed. In
clear contrast, thermolysis of hexane solutions of the pentafluorophenyl hydride complexes
trans-(η5-C5Me4CH2L)Re(CO)2(C6F5)(H), even under CO atmosphere, yields the chelated
complexes (η5:ηx-C5Me4CH2L)Re(CO)2 (8a , L ) -CH2CHdCH2, x ) 2; 8b, L ) -2-C4H3S, x
) 1). However, prolonged thermal treatment of 8b under a CO atmosphere affords the
corresponding tricarbonyl complex 7b. The molecular structures of 8a and 9b have been
determined. Both molecules exhibit formal three-legged piano-stool structures, with three
terminal ligands in 9b (two CO and one PMe3), but in the case of 8a , in addition to the two
CO’s, the third position corresponds to the η2-coordination of the butenyl substituent of the
η5-C5Me4 ring. Attempts to displace the coordinated sidearm in complex 8a have been
investigated, as well as the photochemical reactions of tricarbonyl complexes 7.
In tr od u ction
However, few half-sandwich compounds of this type are
known for group 7 metals. For instance, Casey and
Wang have reported the preparation of manganese
complexes of the type (η5-C5H4L)Mn(CO)3, where L is a
haloalkyl or an aminoalkyl chain, which upon irradia-
tion photodissociate a CO ligand to form the chelated
species (η5:η1-C5H4L)Mn(CO)2 by intramolecular coor-
dination of the halide or the amino group to the metal
center.10,11 Several reports dealing with rhenium com-
plexes containing this type of ligand have been pub-
lished in the past decade. For example, Wang has syn-
thesized and explored the chemistry of the amino-
rhenium complex (η5:η1-C5H4CH2NHCH3)Re(CO)2;12
Functionalized cyclopentadienyl complexes of transi-
tion metals have attracted significant interest in recent
years.1-4 J utzi,1 Siemeling,3a and Butenschon3b have
recently reviewed the chemistry of metal complexes
possessing this type of ligand. Although most of the
work in this area has been focused on early transition
metal complexes for their application as catalysts for
olefin polymerization, there are several examples of
complexes of the medium and late transition metals.1,5-9
* Corresponding author. E-mail: hklahn@ucv.cl. Fax: (56)-(32)-
273422.
† Universidad Cato´lica de Valparaiso.
‡ Universidad de Zaragoza-CSIC.
(6) Ogo, S.; Makihara, N.; Kaneko, Y.; Watanabe, Y. Organometallics
(1) J utzi, P.; Mu¨ller, C.; Vos, D. J . Organomet. Chem. 2000, 600,
127, and references therein.
(2) Slone, C. S.; Weinberger, D. A.; Mirkin, C. A. In Progress in
Inorganic Chemistry; Wiley & Sons: New York, 1999; Vol. 48, p 233.
(3) (a) Siemeling, U. Chem. Rev. 2000, 100, 1495. (b) Butenscho¨n,
H. Chem. Rev. 2000, 100, 1527.
(4) For a historical perspective on functionalized cyclopentadienyl
ligands and related complexes, see: Macomber, D. W.; Hart, W. P.;
Rausch, M. D. Adv. Organomet. Chem. 1982, 21, 1.
(5) Enders, M.; Ludwig, G.; Pritzkow, H. Organometallics 2001, 20,
827.
2001, 20, 4903.
(7) Ciruelos, S.; Englert, U.; Salzer, A. Organometallics 2000, 19,
2240.
(8) Groux, L. F.; Be´langer-Garie´py, F.; Zargarian, D.; Vollmerhaus,
R. Organometallics 2000, 19, 1507.
(9) Fryzuk, M.; J afarpour, L.; Rettig, S. J . Organometallics 1999,
18, 4050.
(10) Casey, C. P.; Czerwinski, C. J .; Fraley, M. E. Inorg. Chim. Acta
1998, 280, 316.
(11) Pang, Z.; Burkey, T. J .; J ohnston, R. F. Organometallics 1997,
16, 120.
10.1021/om030443m CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/17/2003

4862 Organometallics, Vol. 22, No. 24, 2003
Godoy et al.
Casey has prepared and used (η5-C5H4L)Re(CO)3 com-
plexes (L ) 2-iodoethyl and 2-propenyl), as precursors
of chelated metal acyl hydride and hydroxycarbene
complexes (η5:η1-C5H4CH2CH2CO)Re(CO)2H and (η5:η1-
C5H4CH2CH2COH)Re(CO)2;13 Katznellenbogen has de-
veloped a general synthetic method for the preparation
of substituted Cp rhenium tricarbonyl complexes in
order to incorporate the CpRe(CO)3 motif in radio-
pharmaceuticals.14
Sch em e 1
On the other hand, side chain functionalized tetra-
methylcyclopentadienyl complexes are by far less abun-
dant than their cyclopentadienyl analogues. Most of the
synthetic approaches for the preparation of such kinds
of complexes involve the prior synthesis of the target
ligand, which is normally prepared by extension of some
of the classical methods for the synthesis of penta-
methylcyclopentadiene.15,16 An alternative way to func-
tionalized tetramethylcyclopentadienyl transition metal
complexes considers, first, the C-H activation of one of
the methyl groups on a parent pentamethylcylopenta-
dienyl complex of the type (η5-C5Me5)MLn, leading to a
formal fulvene complex (η6-C5Me4CH2)MLn, and then
using the reactivity of the exocyclic methylene carbon
to introduce organic functionalities.17,18 Maitlis has
extensively explored this approach with the complex
{(η6-C5Me4CH2)RuCl2}2.18
In previous publications, we have demonstrated that
the rhenium tetramethylfulvene complex (η6-C5Me4CH2)-
Re(CO)2(C6F5) can be used as a convenient starting
material for the preparation of a series of pentamethyl-
cyclopentadienyl complexes.19 For instance, (η6-C5Me4-
CH2)Re(CO)2(C6F5) reacts with HX (X ) Cl, Br, I) to
yield (η5-C5Me5)Re(CO)2(C6F5)X. Ring-substituted cyclo-
pentadienyl complexes (η5-C5Me4CH2X)Re(CO)2(C6F5)X
(X ) Cl, Br, I), [(η5-C5Me4CH2OMe)Re(CO)2(C6F5)]-, and
the zwitterion (η5-C5Me4CH2PMe3)Re(CO)2(C6F5) can be
obtained by reaction of (η6-C5Me4CH2)Re(CO)2(C6F5)
with halogens (X2), MeO- and PMe3, respectively. Very
recently, we have found that the new fulvene complexes
(η6-C5Me4CH2)Re(CO)2X (X ) Cl, Br, I) react at the
exocyclic methylene carbon, with hydrogen halides (HX′)
and halogens (X′2) to form the mixed-halide com-
plexes cis-(η5-C5Me5)Re(CO)2XX′ (X * X′) and cis-(η5-
C5Me4CH2X′)Re(CO)2XX′, respectively.20
In this work we report on the reactions of the fulvene
complexes (η6-C5Me4CH2)Re(CO)2R (1, R ) C6F5; 2, R
) I) with nucleophiles bearing alkenyl or thienyl groups,
leading to the formation of functionalized tetramethyl-
cyclopentadienyl rhenium methyl or hydride com-
plexes: (η5-C5Me4CH2L)Re(CO)2(R)(Me) (3, R ) C6F5;
4, R ) I) and (η5-C5Me4CH2L)Re(CO)2(R)(H) (5, R )
C6F5; 6, R ) I), with L ) -CH2CHdCH2, -2-C4H3S,
respectively. In addition, we show that the hydride
complexes 5 and 6 undergo thermal reductive elimina-
tion reactions which, depending on the nature of the R
group attached to the metal, result in the production of
tricarbonyl (or dicarbonyl phosphine) complexes with
dangling uncoordinated functionalities, or in the coor-
dination of the lateral function to rhenium to yield the
new chelated tetramethylcyclopentadienyl complexes.
(12) (a) Wang, T.-F.; Hwu, C.-C.; Tsai, C.-W.; Wen, Y.-S. J . Chem.
Soc., Dalton Trans. 1998, 2091. (b) Wang, T.-F.; Hwu, C.-C.; Tsai, C.-
W.; Wen, Y.-S. Organometallics 1998, 17, 131. (c) Wang, T.-F.; Hwu,
C.-C.; Tsai, C.-W.; Lin, K.-J . Organometallics 1997, 16, 3089. (d) Wang,
T.-F.; Hwu, C.-C.; Tsai, C.-W.; Wen, Y.-S. Organometallics 1997, 16,
1218.
(13) Casey, C. P.; Czerwinski, C. J .; Fusie, K. A.; Hayashi, R. K. J .
Am. Chem. Soc. 1997, 119, 3971.
(14) (a) Cesatti, R. R.; Katzenellenbogen, J . A. J . Am. Chem. Soc.
2001, 123, 4093. (b) Minutolo, F.; Katzenellenbogen, J . A. Organo-
metallics 1999, 18, 2519.
Resu lts a n d Discu ssion
Syn th eses a n d Rea ction s of th e F u lven e Com -
p lexes. The fulvene complexes (η6-C5Me4CH2)Re-
(CO)2(R) (1, R ) C6F5; 2, R ) I) were prepared from
Cp*Re(CO)3 (Cp* ) η5-C5Me5) and Cp*Re(CO)2I2, re-
spectively, according to methods described in the lit-
erature.19,20 Addition of an excess of allylmagnesium
chloride or 2-thienyllithium to THF solutions of 1 or 2
provided the anionic rhenium complexes [(η5-
C5Me4CH2L)Re(CO)2R]- (L ) -CH2CHdCH2, -2-C4H3S)
(see Scheme 1). The anionic species were not isolated
and were identified by IR spectroscopy. The two promi-
(15) Quindt, V.; Saurenz, D.; Schmitt, O.; Scha¨rr, M.; Dezember,
T.; Wolmersha¨user, G.; Sitzmann, H. J . Organomet. Chem. 1999, 579,
376.
(16) For some recent examples of the syntheses and use of C5Me4RH
ligands see: (a) Gable, K. P.; Brown, E. C. Organometallics 2003, 22,
3096. (b) Enders, M.; Ludwig, G.; Pritzkow, H. Organometallics 2001,
20, 827. (c) van Leusen, D.; Beetstra, D. J .; Hessen, B.; Teuben, J . H.
Organometallics 2000, 19, 4084. (d) Christie, S. D. R.; Man, K. W.;
Whitby, R. J .; Slawin, A. M. Z. Organometallics 1999, 18, 348. (e) Chen,
Y.-X.; Fu, P.-F.; Stern, C. L.; Marks, T. J . Organometallics 1997, 16,
5958.
(17) Brunner, H.; Watcher, J . Organometallics 1996, 15, 1327.
(18) Knowles, D. R. T.; Adams, H.; Maitlis, P. Organometallics 1998,
17, 1741, and references therein.
(19) Klahn, A. H.; Oelckers, B.; Godoy, F.; Garland, M. T.; Vega,
A.; Perutz, R. N.; Higgitt, C. L. J . Chem. Soc., Dalton Trans. 1998,
3079.
(20) Godoy, F.; Klahn, A. H.; Oelckers, B. J . Organomet. Chem. 2002,
662, 130.

(η5-Tetramethylcyclopentadienyl) Re Complexes
Organometallics, Vol. 22, No. 24, 2003 4863
Sch em e 2
nent absorption bands (ν(CO)), observed in the 1880-
1730 cm-1 region, are comparable to those reported for
analogous anionic compounds.21,22 Reaction of the anions
bearing the 3-butenyl or (2-thienyl)methyl side chains
on the tetramethylcylopentadienyl ligand with CH3I at
room temperature yielded the methyl complexes (η5-
C5Me4CH2L)Re(CO)2(R)(Me) (3, 4) (Scheme 1). These
alkyl complexes were isolated in moderate to good yields
(30-65%) as white or pale yellow solids for R ) C6F5
(3) and as yellow-orange solids for R ) I (4). In all cases,
the presence of the methyl groups and the corresponding
sidearm of the tetramethylcyclopentadienyl-substituted
Sch em e 3
1
ligands were inequivocally established by H and 13C
NMR spectroscopies (see Experimental Section). The
stereochemistry of these derivatives was assigned by a
combination of IR and 13C NMR spectroscopies and by
comparison with analogous complexes.23 In the case of
the methyl iodo complexes, mixtures of cis and trans
isomers were obtained (only the trans isomer is shown
in Scheme 1), whereas for the methyl pentafluorophenyl
complexes, the trans isomers were exclusively formed.
On the other hand, the anionic species [(η5-
C5Me4CH2L)Re(CO)2R]- were also reacted in situ with
HCl at low temperature to give the hydride complexes
trans-(η5-C5Me4CH2L)Re(CO)2(R)(H) (5, 6) (see Scheme
1). These compounds showed characteristic CO absorp-
tion bands in the 2022-1945 cm-1 region in THF
solution, similar to those observed in analogous fluoro-
aryl complexes.22,24 The slow decomposition of these
compounds in THF or hydrocarbon solvents precluded
their isolation as pure samples. However, we were able
to characterize the complex trans-(η5-C5Me4CH2CH2-
CHdCH2)Re(CO)2(I)(H) (6a ) in solution by 1H NMR
spectrocopy. As far as we know, the only previous
example of a neutral dicarbonylhalohydride complex of
rhenium reported in the literature is the complex trans-
Cp*Re(CO)2(Br)H.25
Rea ction s of th e F u n ction a lized Tetr a m eth yl-
cyclop en ta d ien yl Com p lexes. Both the methyl and
the hydrido complexes described above are useful start-
ing materials to explore the potentiality of the lateral
function to coordinate to the rhenium center. Consider-
ing that the protonation of transition metal methyl
complexes has been suggested as one of the best and
cleanest methods for the syntheses and isolation of
organometallic Lewis acids,26 we reacted our methyl
derivatives with HBF4, with the aim to form the
chelated cationic complexes [η5:ηx-C5Me4CH2L)Re-
(CO)2(R)]+ (R ) C6F5, I). However, in no cases could
cationic species be detected, and the complexes were
recovered unreacted. Attempts to reductively eliminate
C6F5Me or MeI under several experimental conditions
(thermal and photochemical) were also unsuccessful,
with complexes remaining intact in most cases.
Then, we turned to the hydride complexes. Crude
samples of 5 and 6 dissolved in hexanes under a CO
atmosphere undergo reductive elimination reactions
very easily (25-90 °C). However, the observed product
depends on the nature of the group R coordinated to
rhenium. Iodo hydride complexes 6 generated the tri-
carbonyl complexes (η5-C5Me4CH2L)Re(CO)3 7a ,b (L )
-CH2CHdCH2, 2-C4H3S), which were isolated as pale
yellow solids (Scheme 2). The tricarbonyl derivative 7a
has been synthesized very recently by an independent
route.16a The thiophene derivative 7b could be obtained
in much better yield by an alternative route (vide infra).
To demonstrate the elimination of HI from the decom-
position reactions of 6a ,b, the resulting mixture after
the thermolysis of 6a was extracted with water and then
treated with AgNO3, producing quantitative precipita-
tion of AgI. Complexes 7a ,b showed CO absorption
bands, in hexanes solution, at 2013 and 1923 cm-1
,
almost identical to those observed for Cp*Re(CO)3. In
addition, their 1H, 13C NMR and mass spectra (see
Experimental Section) are consistent with the proposed
structures. As far as we are aware, no other well-
documented thermally induced reductive elimination of
hydrogen halide from four-legged piano-stool rhenium
complexes has been reported in the literature.27
A different reaction pathway seems to occur in the
thermolysis of the pentafluorophenyl hydride complexes
5a ,b (Scheme 3). Under the same experimental condi-
tions described for iodo hydride derivatives, 5a gener-
ated in good yield the chelated tetramethylcyclopenta-
dienyl complex (η5:η2-C5Me4CH2CH2CHdCH2)Re(CO)2
(8a ), instead of the tricarbonyl derivative 7a . The latter
was formed only in trace amounts, as indicated by the
IR spectrum of the reaction mixture, although the
(21) For species with magnesium as the counterion, two broad CO
absorption bands of equal intensity were observed, whereas for species
with lithium as a counterion, three broad CO absorption bands were
observed.
(22) Godoy, F.; Higgitt, C. L.; Klahn, A. H.; Oelckers, B.; Parsons,
S.; Perutz, R. N. J . Chem. Soc., Dalton Trans. 1999, 2039.
(23) Leiva, C.; Klahn, A. H.; Godoy, F.; Toro, A.; Manr´ıquez, V.;
Wittke, O.; Sutton, D. Organometallics 1999, 18, 339.
(24) Carbo, J . J .; Eisenstein, O. Higgitt, C. L.; Klahn, A. H.; Maseras,
F.; Oelckers, B.; Perutz, R. N. J . Chem. Soc., Dalton Trans. 2001, 1452.
(25) Nunn, C. M.; Cowley, A. H.; Lee, S. W.; Richmond, M. G. Inorg.
Chem. 1990, 29, 2105.
(27) A brief mention of the thermal decomposition of the complex
Cp*Re(CO)2(Br)H to form Cp*Re(CO)3 is described in ref 25.
(26) Beck, W.; Su¨nkel, K. Chem. Rev. 1988, 88, 1405.

4864 Organometallics, Vol. 22, No. 24, 2003
Godoy et al.
Sch em e 4
an excess of PMe3. The dicarbonyl trimethylphos-
phine complexes (η5-C5Me4CH2L)Re(CO)2(PMe3) 9 (L )
-CH2CHdCH2, 9a ; L ) 2-C4H3S, 9b) were formed in
good yield from the iodo hydride complexes 6; however,
the thermal reaction of trans-(η5-C5Me4CH2CH2CHd
CH2)Re(CO)2(C6F5)(H) (5a ) afforded a 5:2 mixture of the
complexes 8a and 9a . The two trimethylphosphine
derivatives 9a ,b showed almost the same 31P NMR and
IR spectra (in the carbonyl region) as those reported for
their unsubstituted analogue Cp*Re(CO)2PMe3,33 where-
as the 1H and 13C NMR spectra clearly showed the
presence of the dangling arm of the tetramethylcyclo-
pentadienyl ligand. Additionally, the complex (η5-
C5Me4CH2-2-C4H3S)Re(CO)2(PMe3) (9b) was studied by
X-ray crystallography (vide infra).
reaction was done under a CO atmosphere. When the
reaction was carried out under nitrogen (without CO),
extensive decomposition occurred: 7a and 8a as well
as several others carbonyl-containing products were
observed by IR spectroscopy.
However, in the case of the thermolysis of the hydride
complex with the (2-thienyl)methyl lateral chain, 5b,
the chelated complex (η5:η1-C5Me4CH2(2-C4H3S))Re-
(CO)2 (8b) was observed only as a reaction intermediate,
and prolonged heating resulted in the formation of the
tricarbonyl complex 7b. The lability of this type of
compound is not surprising since most of the metal-S
bound thiophene groups easily dissociate, even when the
thiophene is part of a cyclopentadienyl chelated ligand,
like in the complex [(η5:η1-C5H4CH2C4H3S)Ru(PPh3)2]+.28
Angelici has explained this behavior in terms of elec-
tronic effects.29 Presumably the electron density pro-
vided by the four methyl groups of the cyclopentadienyl
ligand in 8b reduces the Lewis acid character of the Re,
which weakens the bond with the electron-donating
sulfur atom in the chelated complex 8b. Nevertheless
complex 8b was obtained by irradiation of complex 7b
in hexanes solution (Scheme 4). Photoextrusion of CO
from hexane solutions of complex 5a also afforded the
Re-alkene bonded complex 8a .
A tentative mechanistic proposal that could explain
the formation of the tricarbonyl complexes from the
thermolysis of the iodo hydride complexes 6 and the
almost exclusive formation of the chelated derivatives
from the pentafluorophenyl hydride complexes 5, in the
presence of CO, is shown in Scheme 5.
For the pentafluorophenyl hydride case, we assume
an intramolecular reductive elimination of C6F5H with
formation of an intermediate of the type (η5-C5Me4CH2-
CH2CHdCH2)Re(CO)2(η2-C6F5H). Previously, we have
demonstrated that the hydrido complex trans-Cp*Re-
(CO)2(2,5-C6H3F2)H converts thermally to the more
stable Cp*Re(CO)2(2,3-η2-1,4-C6H4F2).24 By considering
the low stability of the Re-(η2-arene) moiety with regard
to substitution,34 it is not surprising that the sidearm
ligand of the cyclopentadienyl group coordinates intra-
molecularly to produce the more stable chelated com-
plexes.
On the other hand, an ionic mechanism can be
envisaged for the reductive elimination of HI from the
iodo hydride complexes. First, we have considered the
ionization of the iodide ligand followed by coordination
of the sidearm, to form the cationic [(η5:ηx-C5Me4CH2L)-
Re(CO)2H]+. Even though we do not have direct ex-
perimental evidence for the formation of the chelated
cation, we do know that the related complex [(η5:η1-
C5Me4CH2PPh2)Re(CO)2H]+ reacts with CO to yield the
tricarbonyl complex (η5-C5Me4CH2PPh2)Re(CO)3.35
In an effort to explore the reactivity of the function-
alized tetramethylcyclopentadienyl ligands coordinated
to rhenium, complexes 8a ,b were treated with CO and
PMe3. We found that only the complex containing the
weakly chelating thiophene moiety reacted with CO (1
atm of pressure in hexanes solution) to form the
tricarbonyl derivative 7b (Scheme 4), whereas with
PMe3 complex 9b was obtained in good yield. For
complex 7b the process is reversible under UV irradia-
tion (hexanes solution, room temperature, λ ) 300 nm).
Under similar conditions, the phosphine complex 9b
decomposed to unidentified products.
The chelated complexes 8a ,b were isolated as solid
samples that showed different properties; for instance,
8a is air stable as a solid and in solution of most organic
solvents. In contrast yellow 8b decompose slowly to 7b
in both solution and solid state. Infrared data for
complexes 8a ,b are consistent with an increase of the
electron density at rhenium from 8a to 8b, as expected.
The presence of four distinct methyl resonances ob-
1
served in the H and 13C NMR spectra of complex 8a
agrees well with the unsymmetrical nature of the tether
alkene coordinated to rhenium and the restricted rota-
tion of the η5:η2-tetramethylcyclopentadienyl(butenyl)
ligand. This result is in good agreement with the
inequivalent resonances measured for the two CO
ligands in the 13C NMR spectrum. Further confirmation
of the structure of complex 8a was obtained from an
X-ray diffraction study (vide infra). To the best of our
knowledge, 8a is the first complex containing the 1-(3-
butenyl)-2,3,4,5-tetramethylcyclopentadienyl ligand co-
ordinated in a η5:η2 fashion to rhenium. Other metal
complexes containing the same ligand reported previ-
ously are (η5:η2-C5Me4CH2CH2CHdCH2)CoL (L ) CO,
C2H4),30 [(η5:η2-C5Me4CH2CH2CHdCH2)Ni(PPh3)]+, 30
and [(η5:η2-C5Me4CH2CH2CHdCH2)Ru(η3-C3H5).32
With the aim of having a more complete view of the
thermolysis of the hydrido complexes 5 and 6, we carried
out the reactions in hexanes solution in the presence of
(30) (a) Zimmermann, K. H.; Pilato, R. S.; Horvath, I. T.; Okuda, J .
Organometallics 1992, 11, 3935. (b) Zimmermann, K. H.; Okuda, J .
Chem. Ber. 1989, 122, 1645.
(31) Lehmkuhl, H.; Na¨ser, J .; Mehler, G.; Keil, T.; Danowski, F.;
Benn, R.; Mynott, R.; Schroth, G.; Gabor, B.; Kru¨ger, C.; Betz, P. Chem.
Ber. 1991, 124, 441.
(32) Castro, A.; Turner, M. L.; Maitlis, P. M. J . Organomet. Chem.
2003, 674, 45.
(33) Bergman, R. G.; Seidler, P. F.; Wenzel T. T. J . Am. Chem. Soc.
1985, 107, 4358.
(34) Bengali, A. A.; Leicht, A. Organometallics 2001, 20, 1345.
(35) Godoy, F.; Klahn, A. H., unpublished results.
(28) Draganjac, M.; Ruffing, C. J .; Rauchfuss, T. B. Organometallics
1985, 4, 1909.
(29) Choi, M.-G.; Angelici, R. J . Organometallics 1992, 11, 3328.

(η5-Tetramethylcyclopentadienyl) Re Complexes
Organometallics, Vol. 22, No. 24, 2003 4865
Sch em e 5
Attempts to displace thermally the coordinated bu-
tenyl sidearm in complex 8a with excess PMe3 or CO,
even under 2000 psi, were unsuccessful, whereas com-
plete decomposition was observed after UV irradiation.
However, the chelated ligand of 8a can be displaced
irreversibly upon oxidative addition of I2 to the Re(I)
center to yield the complex cis-(η5-C5Me4CH2CH2CHd
CH2)Re(CO)2I2. The latter compound was characterized
1
by mass spectrometry, IR, and H NMR spectroscopies.
The IR spectrum of this complex shows identical ν(CO)
absorption bands to those reported for cis-Cp*Re-
(CO)2I2.36
X-r a y Str u ctu r e of 8a a n d 9b. Molecular structures
of complexes 8a and 9b are shown in Figures 1 and 2,
respectively. Table 1 collects the most relevant bond
distances and angles. Both molecules exhibit analogous
three-legged piano-stool structures. In 9b, three termi-
nal ligands (two carbonyls and a PMe3) occupy the
coordination sphere of the metal together with an η5-
coordination of the C5Me4(CH2-2-C4H3S) cyclopentadi-
enyl moiety. However, in the case of 8a an η5:η2 chelate
bonding mode of a 3-butenyl-functionalized cyclopenta-
dienyl ligand, together with two terminal carbonyl
ligands, completes the rhenium coordination.
F igu r e 1. Molecular structure of the chelated complex (η5:
η2-C5Me4CH2CH2CHdCH2)Re(CO)2 (8a ) drawn with 50%
probability displacement ellipsoids.
Only two other transition metal compounds with an
alkenyl-substituted C5Me4 ring coordinated in an η5:η2
bonding mode have been structurally characterized: (η5:
η2-C5Me4CH2CH2CHCH2)Co(Me3SiCCSiMe3)37 and, very
recently, (η5:η2-C5Me4CH2CH2CHCH2)Ru(η3-C3H5).32
There is also a reduced number of structurally charac-
terized related complexes possessing longer lateral
chains, some of them including oxygen atoms in the
chelating arms; these are the cases of (η5:η2-C5Me4-
CH2(CH2)2CHCH2)NiBr,31 [(η5:η2-C5Me4CH2O(CH2)n-
CHCH2)Ru(CO)2]+ (n ) 1, 2),38 or (η5:η2-C5Me4CH2O-
(CH2)2CHCH2)Ru(CO)(COOMe).39 The related 1,2-bis-
(indenyl)ethane complexes [(η5-C9H6)CH2CH2(η2-C9H6)]-
M(CO)2 (M ) Mn, Re) have also been reported, including
the X-ray structure of the manganese derivative.40
Unique structural features of 8a have been sought
by comparison with related nonchelated Cp*Re(CO)2-
F igu r e 2. Molecular structure of complex (η5-C5Me4CH2-
2-C4H3S)Re(CO)2(PMe3) (9b) drawn with 50% probability
displacement ellipsoids.
(36) Einstein, F. W. B.; Klahn, A. H.; Sutton, D.; Tyers, K. G.
Organometallics 1986, 5, 53.
(37) Okuda, J .; Zimmermann, K. H.; Herdtweck, E. Angew. Chem.,
Int. Ed. Engl. 1991, 30, 430.
(38) Gusev, O. V.; Morozova, L. N.; O’Leary, S. R.; Adams, H.; Bailey,
N. A.; Maitlis, P. M. J . Chem. Soc. Dalton Trans. 1996, 2571.
(39) Gusev, O. V.; Morozova, L. N.; Peganova, T. A.; Antipin, M. Y.;
Lyssenko, K. A.; Noels, A. F.; O’Leary, S. R.; Maitlis, P. M. J .
Organomet. Chem. 1997, 536, 191.
(η2-(CH3)2CdCHCOMe), to our knowledge the only other
Cp*Re(CO)2(η2-olefin) complex studied by X-ray crystal-
lography.41 In terms of the Re-CO (1.877, 1.912 Å) and
Re-C(ring centroid) (1.937 Å) bond distances, the
(41) Einstein, F. W. B.; J ones, R. H.; Klahn, A. H.; Sutton, D.
(40) Khayatpoor, R.; Shapley, J . R. Organometallics 2000, 19, 2382.
Organometallics 1986, 5, 2476.

4866 Organometallics, Vol. 22, No. 24, 2003
Godoy et al.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p lexes 8a a n d 9b
as received. 2-Thienyllithium was prepared according to
literature.43 The fulvene complexes (η6-C5Me4CH2)Re(CO)2-
(C6F5) (1) and (η6-C5Me4CH2)Re(CO)2I (2) were prepared
according to known procedures.19,20 Infrared spectra were
recorded in solution (CaF2 cell) on a Perkin-Elmer FT-1605
spectrophotometer. 1H and 13C NMR spectra were recorded on
a Bruker AC 200 (200 MHz) instrument. All 1H NMR chemical
shifts are referenced using the chemical shifts of residual
solvent resonances. 13C NMR chemical shifts were referenced
to solvent peaks. Coupling assignments are indicated, where
known. Mass spectra were run on a GCMS-QP5050A Shi-
madzu instrument.
In Situ P r ep a r a tion of An ion ic [(η5-C5Me4CH2L)Re-
(CO)2R]- Sp ecies. The amounts of (η6-C5Me4CH2)Re(CO)2-
(C6F5) (1) or (η6-C5Me4CH2)Re(CO)2I (2) indicated in each case
(see below) were dissolved in THF (10-15 mL). Then, 2 equiv
of the organolithium or Grignard reagent were added dropwise
at 0 °C. After the addition, all reaction mixtures became pale
yellow, except that treated with thienyllithium, which became
orange. In all cases, strong CO absorption bands were observed
in the 1880-1730 cm-1 infrared region.21
8a
9b
Re-P
2.3424(8)
1.882(1)
1.891(1)
Re-C(1)
1.877(6)
1.912(7)
2.298(6)
2.233(6)
2.253(6)
2.282(6)
2.314(7)
2.311(6)
2.298(6)
1.937(3)
1.165(7)
1.145(7)
1.413(11)
1.502(9)
1.536(8)
1.479(8)
Re-C(2)
Re-C(3)
Re-C(4)
Re-C(7)
2.273(1)
2.271(1)
2.312(1)
2.343(1)
2.317(1)
1.9541(13)
1.166(3)
1.163(4)
1.455(4)
1.445(5)
1.340(5)
1.502(4)
Re-C(8)
Re-C(9)
Re-C(10)
Re-C(11)
Re-centroid(C5Me4CH2L)
C(1)-O(1)
C(2)-O(2)
C(3)-C(4)
C(4)-C(5)
C(5)-C(6)
C(6)/C(12)-C(7)
P/M#-Re-C(1)a
P/M#-Re-C(2)
C(1)-Re-C(2)
Re-C(1)-O(1)
Re-C(2)-O(2)
C(3)-C(4)-C(5)
C(4)-C(5)-C(6)
C(5)-C(6)-C(7)
98.41(20)
95.63(20)
87.4(3)
175.2(5)
178.4(6)
123.3(6)
113.0(5)
110.9(5)
Meth yl Com p lexes 3 a n d 4. An excess of CH3I was added
to the solution of the corresponding anionic species. The
mixtures were stirred at room temperature for 24 h, and then
the solvent was removed under vacuum. The solid residue was
chromatographed using a short alumina column. Elution with
hexanes or the appropiate mixture of solvents (see below)
moved the corresponding methyl complex.
91.39(13)
173.2(3)
177.4(3)
a
M# represents the midpoint of the olefinic double bond C(3)-
tr a n s-(η5-C5Me4CH2CH2CHdCH 2)R e(CO)2(C6F 5)(CH3),
3a . A 150 mg (0.28 mmol) sample of 1 was reacted. Complex
3a was isolated as a white solid after crystallization from
hexanes. Yield: 108 mg (0.18 mmol), 65%. IR (hexanes, ν(CO),
C(4) in 8a .
molecular parameters of 8a compare well with those
found in Cp*Re(CO)2(η2-(CH3)2CdCHCOMe)41 (Re-CO
1.851, 1.875 Å and Re-Cp* (centroid) 1.974 Å). The Re-
C(olefin) distances are also comparable in the two
complexes (2.232 and 2.330 Å vs 2.233 and 2.298 Å in
8a ) as well as the OC-Re-CO and C(olefin)-Re-
C(olefin) interbond angles (87.4 and 36.4° vs 87.3 and
36.9°, respectively).
1
cm-1): 2022(s), 1954(vs). H NMR (CDCl3) δ: 0.81 (s, 3H, Re-
CH3), 1.76 (s, 6H, CH3), 1.77 (s, 6H, CH3), 2.10 (m, 4H,
-CH2CH2-), 5.01 (m, 2H, -CHdCH2), 5.77 (m, 1H, -CHd
CH2). 13C{1H} NMR (CDCl3) δ: -16.85 (Re-CH3), 9.56 (CH3),
9.62 (CH3), 24.37 (-CH2-), 34.02 (-CH2-), 100.00 (C5Me4),
100.66 (C5Me4), 102.48 (C5Me4), 115.91 (-CHdCH2), 136.96
(-CHdCH2), 196.30 (t, J CF ) 4.7 Hz, CO); aromatic carbons
of C6F5 not seen. MS (EI, based on 187Re) m/z: 600 [M+], 555
[M+ - CO - CH3 - 2H]. Anal. Calcd for C22H22F5O2Re: C,
44.07; H, 3.70. Found: C, 44.15; H, 3.82.
tr a n s-(η5-C5Me4CH2(2-C4H3S))Re(CO)2(C6F 5)(CH3), 3b.
A 150 mg (0.28 mmol) sample of 1 was reacted. Elution with
hexanes moved 3b, which was obtained as a pale yellow solid
after evaporation of the solvent. Yield: 104 mg (0.16 mmol),
59%. IR (hexanes, ν(CO), cm-1): 2022(s), 1955(vs). 1H NMR
(CDCl3) δ: 0.88 (s, 3H, Re-CH3); 1.79 (s, 6H, CH3), 1.80 (s, 6H,
CH3), 3.56 (s, -CH2-), 6.72 (m, 1H, C4H3S), 6.91 (dd, J ) 5.1,
3.5 Hz, 1H, C4H3S), 7.13 (dd J ) 5.1, 1 Hz, 1H, C4H3S). 13C{1H}
NMR (CDCl3) δ: -16.71 (Re-CH3); 9.60 (CH3), 9.77 (CH3),
25.27 (-CH2-), 100.02 (C5Me4), 100.67 (C5Me4), 100.12 (C5Me4),
Interestingly, we could not identify a clear reason to
justify the asymmetry of the interaction between the
olefin and the metal, Re-C(3) vs Re-C(4). In that sense,
we could not discern either an electronic delocalization
or a source of strain in the bridging arm connecting the
η5-C5Me4 ring with the olefin: all the bond distances
and angles of the arm seem to be normal for single
bonds between sp3 carbon atoms (see Table 1) and very
similar to those observed in the closely related ruthe-
nium complex (η5:η2-C5Me4CH2CH2CHCH2)Ru(η3-C3H5),
where a symmetric Ru-olefin interaction has been
determined (Ru-C(olefin) 2.167(4) and 2.161(4) Å).32
The structure of 9b resembles that of the related
complex Cp*Re(CO)2(PPh3)42 with the sole changes of
the substitution of the phosphine (PMe3 vs PPh3) and
the thiophene presence as a sidearm in the η5-C5Me4
ring. No special bonding parameter, including the Re-P
bond length (2.3424(8) in 9b vs 2.341(10) Å in Cp*Re-
(CO)2(PPh3)), differs significantly in both structures,
despite the greater σ-donor capacity of the PMe3 ligand.
124.04 (C4H3S), 125.11 (C4H3S), 139.91 (C4H3S); 142.09 (Cipso
,
2-C4H3S), 195.75 (t, J CF ) 6.3 Hz, CO). MS (EI, based on 187Re)
m/z: 642 [M+], 599 [M+ - CO - Me], 404 [M+ - 2CO - Me -
C6F5]. Anal. Calcd for C23H20O2F5SRe: C, 43.05; H, 3.14.
Found: C, 43.19; H, 3.28.
(η5-C5Me4CH2CH2CHdCH2)Re(CO)2(I)(CH3), 4a . A 100
mg (0.20 mmol) sample of 2 was reacted. Elution with hexanes
afforded the trans isomer as a yellow-orange solid (26 mg,
0.046 mmol, 23% yield), whereas elution with hexanes-CH2Cl2
(9:1) afforded the cis isomer of 4a (23 mg, 0.04 mmol, 21%
yield).
Exp er im en ta l Section
cis Isom er . IR (hexanes, ν(CO), cm-1): 2007(s), 1936(s). 1H
NMR (C6D6) δ: 1.36 (s, 3H, Re-CH3), 1.41 (s, 3H, CH3), 1.45 (s,
3H, CH3), 1.47 (s, 3H, CH3), 1.59 (s, 3H, CH3), 1.72 (m, 2H,
Gen er a l Meth od s. All reactions were carried out under
nitrogen using standard Schlenk techniques. All solvents were
purified and dried by conventional methods and distilled under
nitrogen prior to use. Grignard reagents (Aldrich) were used
(43) Wakefield, B. J . Organolithium Methods; Academic Press:
London, UK, 1990. See also: (b) Chadwick, D. J .; Willbe, C. J . Chem.
Soc., Perkin Trans. 1977. 1, 887. (c) Malmberg, H.; Nilsson, M.
Tetrahedron 1986, 42, 3981.
(42) J oachim, J . E.; Apostolidis, C.; Kanellakopulos, B.; Meyer, D.;
Nuber, B.; Raptis, K.; Rebizant, J .; Ziegler, M. L. J . Organomet. Chem.
1995, 492, 199.

(η5-Tetramethylcyclopentadienyl) Re Complexes
Organometallics, Vol. 22, No. 24, 2003 4867
-CH2-), 2.02 (m, 2H, -CH2-), 4.83 (m, 2H, -CHdCH2), 5.49
(m, 1H, -CHdCH2). 13C{1H} NMR (C6D6) δ: -17.45 (Re-CH3),
10.43 (CH3), 10.64 (CH3), 10.70 (CH3), 11.14 (CH3), 26.26
(-CH2-), 35.55 (-CH2-), 100.37 (C5Me4), 101.38 (C5Me4),
102.03 (C5Me4), 104.50 (C5Me4), 105.11 (C5Me4), 117.03
(-CHdCH2), 137.74 (-CHdCH2), 205.56 (CO), 209.88 (CO).
MS (EI, based on 187Re) m/z: 560 [M+], 530 [M+ - CO - 2H],
517 [M+ - CO - Me]. Anal. Calcd for C16H22O2IRe: C, 34.50;
H, 3.96. Found: C, 34.61; H, 3.78.
tr a n s Isom er . IR (hexanes, ν(CO), cm-1): 2019(s), 1955(vs).
1H NMR (C6D6) δ: 0.72 (s, 3H, Re-CH3); 1.45 (s, 6H, CH3), 1.55
(s, 6H, CH3), 1.79 (m, 2H, -CH2-), 1.98 (m, 2H, -CH2-), 4.86
(m, 2H, -CHdCH2), 5.50 (m, 1H, -CHdCH2). 13C{1H} NMR
(C6D6) δ: -18.15 (Re-CH3), 10.92 (CH3), 10.96 (CH3), 26.13
(-CH2-), 35.70 (-CH2-), 100.50 (C5Me4), 100.79 (C5Me4),
102.61 (C5Me4), 116.75 (-CHdCH2), 138.11 (-CHdCH2),
195.34 (CO). MS (EI, based on 187Re) m/z: 560 [M+], 530 [M+
- CO - 2H], 517 [M+ - CO - Me]. Anal. Calcd for C17H22O2-
IRe: C, 36.50; H, 3.96. Found: C, 36.47; H, 3.83.
(η5-C5Me4CH2(2-C4H3S))Re(CO)2(I)(CH3), 4b. A 150 mg
(0.30 mmol) sample of 2 was reacted. Elution with hexanes
(Florisil) afforded the trans isomer as a yellow-orange solid
(41 mg, 0.07 mmol, 23% yield), whereas elution with hexanes-
CH2Cl2 (4:1) afforded the cis isomer (18 mg, 0.003 mmol, 10%
yield).
cis Isom er . IR (hexanes, ν(CO), cm-1): 2007(vs), 1936(s).
1H NMR (CDCl3) δ: 1.28 (s, 3H, Re-CH3); 1.39 (s, 3H, CH3),
1.45 (s, 3H, CH3), 1.56 (s, 3H, CH3), 1.66 (s, 3H, CH3), 3.41 (s,
2H, -CH2-), 6.39 (m, 1H, C4H3S), 6.60 (dd, J ) 5.2, 3.5 Hz,
1H, C4H3S), 6.70 (dd, J ) 5.2, 1 Hz, 1H, C4H3S). MS (EI, based
on 187Re) m/z: 602 [M+], 574 [M+ - CO], 559 [M+ - CO - Me].
Anal. Calcd for C17H20O2ISRe: C, 33.95; H, 3.35; S, 5.33.
Found: C, 33.97; H, 3.32; S, 5.07.
5.54 (m, 1H, -CHdCH2). 13C{1H} NMR (CDCl3) δ: 10.73 (CH3),
25.36 (-CH2-), 36.10 (-CH2-), 98.49 (C5Me4), 98.94 (C5Me4);
101.34 (Cipso, C5Me4), 115.64 (-CHdCH2), 137.21 (-CHdCH2),
197.90 (CO). MS (EI, based on 187Re) m/z: 446 [M+], 418 [M+
- CO], 405 [M+ - CH2CHdCH2], 388 [M+ - 2CO - 2H]. Anal.
Calcd for C16H19O3Re: C, 43.14; H, 4.30. Found: C, 42.39; H,
3.94.
(η5-C5Me4CH2(2-C4H3S)R e(CO)3, 7b . (a ) F r om 5b . The
hexanes solution containing the hydride complex 5b (prepared
from 1, 240 mg, 0.44 mmol) was heated under CO at 50 °C for
4 days. An IR spectrum recorded at this time showed two
strong absorption bands at 2014 and 1925 cm-1 and minor
absorptions at 2060, 1973, and 1874 cm-1. The reaction
mixture was concentrated under vacuum to ca. 3 mL, and then
it was filtered through a short alumina column (1 cm). 7b was
obtained as a yellow solid after evaporation of the solvent.
Recrystallization from hexanes yielded yellow crystals (70 mg,
0.14 mmol, 32%). (b) F r om 6b. The hexanes solution contain-
ing the iodo hydride complex 6b (prepared from 2, 100 mg,
0.20 mmol) was heated under CO at 70 °C for 4 h and then
chromatographed through a Florisil column. Complex 7b was
eluted with hexanes and obtained as a pale yellow solid, after
solvent evaporation. It was crystallized from hexanes-CH2Cl2
(9:1) to yield 23 mg of a pale yellow microcrystalline powder
(0.048 mmol, 24%). IR (hexanes, ν(CO), cm-1): 2014(s),
1925(vs). 1H NMR (CDCl3) δ: 2.19 (s, 6H, CH3), 2.23 (s, 6H,
CH3), 3.97 (d, 2H, J ) 0.8 Hz, -CH2-), 6.76 (m, 1H, C4H3S),
6.93 (dd, J ) 5.1, 3.5 Hz, 1H, C4H3S), 7.15 (dd, J ) 5.1, 1.1
Hz, 1H, C4H3S). 13C{1H} NMR (CDCl3) δ: 10.76 (CH3), 10.87
(CH3), 26.27 (-CH2-), 98.92 (C5Me4), 99.15 (C5Me4), 99.36
(C5Me4), 123.84 (C4H3S), 124.65 (C4H3S), 126,87 (C4H3S),
143.73 (Cipso, 2-C4H3S), 197.60 (CO). MS (EI, based on 187Re)
m/z: 488 [M+], 460 [M+ - CO], 432 [M+ - 2CO], 404 [M+
-
tr a n s Isom er . IR (hexanes, ν(CO), cm-1): 2019(vs), 1955(s).
1H NMR (CDCl3) δ: 0.71 (s, 3H, Re-CH3), 1.30 (s, 6H, CH3),
1.67 (s, 6H, CH3), 3.41 (d, J ) 1 Hz, 2H, -CH2-), 6.35 (m,
1H, C4H3S), 6.59 (dd, J ) 5.2, 3.4 Hz, 1H, C4H3S), 6.68 (dd, J
) 5.2, 1.2 Hz, 1H, C4H3S). 13C{1H} NMR (CDCl3) δ: -18.27
(Re-CH3), 10.61 (CH3), 11.49 (CH3), 27.49 (-CH2-), 100.71
(C5Me4), 100.88 (C5Me4), 101.89 (C5Me4), 125.16 (C4H3S),
126.35 (C4H3S), 127.98 (C4H3S), 144.20 (Cipso 2-C4H3S), 194.95
(s, CO). MS (EI, based on 187Re) m/z: 602 [M+], 574 [M+ - CO],
559 [M+ - CO - Me]. Anal. Calcd for C17H20O2ISRe: C, 33.95;
H, 3.35; S, 5.33. Found: C, 33.90; H, 3.38; S, 5.40.
Hyd r id e Com p lexes 5 a n d 6. Two equivalents of HCl
solution (1.0 M in diethyl ether) was added to the solution of
the corresponding anionic species at 0 °C. None of the resulting
hydrido complexes were isolated and characterized, except for
(η5-C5Me4CH2CH2CHdCH2)Re(CO)2(I)(H), 6a , which was spec-
troscopically characterized in situ. Instead, the reaction mix-
tures were concentrated under vacuum, and the resulting
residue was exhaustively dried. Hexanes (15 mL) was added,
and the mixture was filtered. The salts were washed twice with
2-10 mL portions of hexanes. The yellow filtrate containing
the hydrido compounds was bubbled with CO for 5 min, and
then the solution was treated as described below for the
synthesis of compounds 7, 8, and 9.
3CO]. Analysis of this compound did not afford satisfactory C
and H values.
(η5:η2-C5Me4CH2CH2CHdCH2)Re(CO)2, 8a . The pale yel-
low filtrate containing 5a , prepared from 1 (150 mg (0.276
mmol), was heated under CO at 50 °C for 24 h. An IR spectrum
recorded at this time showed two strong absorption bands at
1962 and 1892 cm-1 and minor absorptions at 2058, 2014,
1994, and 1924 cm-1. The reaction mixture was concentrated
under vacuum to ca. 3 mL, and then it was filtered through a
short alumina column (2 cm). Elution with hexanes moved 8a ,
contaminated with traces of the tricarbonyl complex 7a .
Recrystallization of 8a from hexanes yielded white crystals
(79 mg, 0.18 mmol, 64%). IR (hexanes, ν(CO), cm-1): 1962(vs),
1
1892(vs). H NMR (CDCl3) δ: 1.66 (dd, 1H, J ) 10.8, 2.6 Hz,
-CH2-); 1.79 (ddd, 1H, J ) 14.6, 12.8, 6.6 Hz, -CH2-); 1.99
(ddd, 1H, J ) 14.6, 8.1, 1.2 Hz, -CH2-), 2.07 (s, 3H, CH3),
2.23 (dd, partially obscured by one methyl resonance, 1H,
-CH2-), 2.25 (s, 3H, CH3), 2.34 (s, 3H, CH3), 2.36 (s, 3H, CH3),
2.89 (m, 1H, -CHdCH2), 3.37 (m, 2H, -CHdCH2). 13C{1H}
NMR (CDCl3) δ: 9.94 (CH3), 11.09 (CH3), 11.64 (CH3), 11.95
(CH3), 16.17 (-CH2-), 24.40 (-CH2-), 42.29 (-CHdCH2),
47.20 (-CHdCH2), 93.61 (C5Me4), 95.00 (C5Me4), 96.01 (C5Me4),
99.67 (C5Me4), 116.02 (Cipso-C5Me4), 207.52 (CO), 207.71 (CO).
MS (EI, based on 187Re) m/z: 418 [M+], 388 [M+ - CO - 2H],
360 [M+- 2CO - 2H]. Anal. Calcd for C15H19O2Re: C, 43.15;
H, 4.59. Found: C, 43.06; H, 4.65.
tr a n s-(η5-C5Me4CH2CH2CHdCH2)Re(CO)2(I)(H), 6a . IR
(hexanes, ν(CO), cm-1): 2022(s), 1956(vs). 1H NMR (C6D6)
δ: -10.93 (s, 1H, Re-H), 1.69 (s, 6H, CH3), 1.73 (s, 6H, CH3);
1.76 (m, 2H, -CH2-), 2.15 (m, 2H, -CH2-), 4.89 (m, 2H,
-CHdCH2), 5.46 (m, 1H, -CHdCH2).
(η5:η1-C5Me4CH2(2-C4H3S)Re(CO)2, 8b. Complex 7b (40
mg, 0.082 mmol) was dissolved in hexanes (4 mL) in a quartz
tube. The solution was irradiated at 35 °C for 1 h (λ ) 300
nm) under N2. A brown solid was formed, and the solution
turned yellow. An IR spectrum of the reaction mixture showed
absorption bands due to the starting complex and new bands
at 1932 and 1874 cm-1. The mixture was filtered at room
temperature and then cooled at 4 °C. Yellow crystals were
formed on the walls, which were washed with cold hexanes to
yield 8 mg of 8b (0.02 mmol, 22%). IR (hexanes, ν(CO), cm-1):
1932(s), 1874(s). 1H NMR (CDCl3) δ: 1.94 (s, 6H, CH3), 2.10
(s, 6H, CH3), 3.88 (s, 2H, -CH2-), 6.75 (m, 1H, C4H3S), 6.90
(η5-C5Me4CH2CH2CHdCH2)Re(CO)3, 7a . The hexanes
solution containing the hydride 6a (prepared from 2, 100 mg,
0.20 mmol) was heated under CO at 90 °C for 10 h. The solvent
was removed under vacuum, and the solid was chromato-
graphed through a short alumina column. Elution with hex-
anes moved 7a (49 mg, 0.11 mmol, 56% yield). IR (hexanes,
ν(CO), cm-1): 2014(s), 1923(vs). 1H NMR (C6D6) δ: 1.67 (s, 6H,
CH3), 1.72 (s, 6H, CH3), 1.82 (m, 2H, -CH2), 2.21 (m, 2H,
-CH2-), 4.83 (m, 1H, -CHdCH2), 4.92 (m, 1H, -CHdCH2),

4868 Organometallics, Vol. 22, No. 24, 2003
Godoy et al.
Ta ble 2. Cr ysta llogr a p h ic Da ta for Com p lexes 8a
a n d 9b
(dd, J ) 5.1, 3.4 Hz, 1H, C4H3S), 7.12 (dd, J ) 5.1, 1.1 Hz, 1H,
C4H3S). 13C{1H} NMR (CDCl3) δ: 10.12 (CH3), 10.36 (CH3),
25.85 (-CH2-), 99.64 (C5Me4), 100.08 (C5Me4), 100.98 (C5Me4),
8a
9b
123.74 (C4H3S), 124.78 (C4H3S), 126,82 (C4H3S), 143.21 (Cipso
,
formula
MW
a, Å
b, Å
c, Å
C
15H19O2Re
C19H26O2PSRe
535.63
10.2133 (6)
12.0658 (7)
16.1707 (9)
90
1992.7 (2)
orthorhombic
P212121
4
2-C4H3S), 213.63 (CO). MS (EI, based on 187Re) m/z: 460 [M+],
404 [M+ - 2CO]. Analysis of this compound did not afford
satisfactory C and H values.
417.50
9.100 (3)
13.557 (4)
10.900 (3)
93.394 (5)
1342.4 (6)
monoclinic
P21/n
(η5-C5Me4CH2CH2CHdCH2)Re(CO)2(P Me3), 9a . Complex
6a , prepared in situ from 100 mg (0.20 mmol) of 2, was reacted
with an excess of PMe3 (0.4 mL, 1.0 M THF solution). After
stirring for 10 min at room temperature, the IR spectrum
showed the complete disappearance of 6a and the presence of
two strong absorption bands at 1911 and 1844 cm-1. Solvent
was pumped off, and the light brown oily residue was extracted
with hexanes (3 × 5 mL) and filtered through a short alumina
column. The solution was concentrated to ca. 3 mL and kept
at -10 °C overnight, to yield 62 mg of 9a as a tan oily solid
(0.13 mmol, 63%). IR (hexanes, ν(CO), cm-1): 1924(s), 1860(s).
1H NMR (C6D6) δ: 1.22 (d, J ) 8.9 Hz, 9H, PMe3), 1.84 (s, 6H,
CH3), 1.90 (s, 6H, CH3), 2.02 (m, 2H, -CH2-), 2.39 (m, 2H,
-CH2-), 4.95 (m, 2H, CHdCH2), 5.70 (m, 2H, CHdCH2).
13C{1H} NMR (C6D6) δ: 12.05 (CH3), 12.11 (CH3), 23.34 (d, J
) 34 Hz, PMe3), 27.41 (-CH2-), 37.44 (-CH2-), 96.69 (C5Me4),
96.78 (C5Me4), 99.98 (C5Me4), 116.08 (CHdCH2), 139.11
(CHdCH2), 206.97 (d, J ) 7.6 Hz, CO). 31P NMR (C6D6) δ:
â, deg
V, Å3
cryst syst
space group
Z
4
θ min-max, deg
2.8-28.8
2.1-28.4
F
calcd, g/cm3
2.066
1.785
µ, mm-1
9.043
8704
3196
196
6.291
13078
4635
317
no. measd reflns
no. indep reflns
no. of params
no. of restraints
GOF
0
0
1.050
9.043
800
1.096
6.291
1048
µ, mm-1
F(000)
transm coeff
R(int)
0.120-0.497
0.0677
0.0448
0.1190
0.190-0.271
0.0156
0.0148
0.0382
R(F) (F2 g 2σ(F2))
Rw(F2) (all data)
-27.9 (s). MS (EI, based on 187Re) m/z: 494 [M+], 453 [M+
CH2CHdCH2], 436 [M+ - 2CO].
-
2θ e 56.76° for 9b. Data were measured through the use of
CCD recording of ω rotation frames (0.3° each). All data were
corrected for Lorentz and polarization effects. Absorption
corrections were applied using the SADABS routine.44 Both
data were integrated with the Bruker SAINTPLUS program.45
(η5-C5Me4CH2(2-C4H3S)Re(CO)2(P Me3), 9b. Following the
same procedure described for 9a , this complex was prepared
from 2 (100 mg, 0.20 mmol). 9b was isolated as a white solid
after crystallization from hexanes at -10 °C. Yield: 64 mg
(0.12 mmol, 60%). IR (hexanes, ν(CO), cm-1): 1920(s), 1856(vs).
1H NMR (C6D6) δ: 1.22 (d, J ) 8.9 Hz, 9H, PMe3), 1.78 (s, 6H,
CH3), 1.97 (s, 6H, CH3), 3.79 (d, J ) 1 Hz, 2H, -CH2-), 6.53
(m, 1H, C4H3S), 6.65 (dd, J ) 5.2, 3.5, 1H, C4H3S), 6.73 (dd, J
) 5.2, 1.2, 1H, C4H3S). 13C{1H} NMR (C6D6) δ: 11.94 (CH3),
12.25 (CH3), 23.32 (d, J ) 34, PMe3), 28.16 (-CH2-), 97.16
(C5Me4), 97.48 (C5Me4), 97.85 (C5Me4), 124.57 (C4H3S), 125.44
(C4H3S), 127.62 (C4H3S), 146.33 (Cipso-C4H3S), 206.75 (d, J )
8.4 Hz, CO). 31P NMR (C6D6) δ: -28.3 (s). MS (EI, based on
187Re) m/z: 536 [M+], 521 [M+ - Me], 508 [M+ - CO]. Anal.
Calcd for C19H26O2PSRe: C, 42.60; H, 4.89. Found: C, 41.54;
H, 4.43.
Both structures were solved by Patterson, completed by
difference Fourier techniques, and refined by full-matrix least-
squares on F2 (SHELXL-97)46 with initial isotropic, but
subsequent anisotropic thermal parameters. Hydrogens in 8a
were included in calculated positions and refined riding on
carbon atoms with free isotropic displacement parameters;
those of the coordinated olefin were refined from observed
positions as free isotropic atoms. In the case of 9b, all
hydrogens were introduced from observed positions and refined
as isotropic atoms. Atomic scattering factors were used as
implemented in the program.45
cis-(η5-C5Me4CH2CH2CHdCH2)Re(CO)2I2. To a solution
of 8a (19 mg, 0.046 mmol) in 4 mL of CH2Cl2 was added 2 mL
of a I2-CH2Cl2 solution (23 mg of I2 in 4 mL of CH2Cl2). An IR
spectrum showed the disappearance of the starting complex
and new absorption bands at 2022 and 1946 cm-1. The solvent
was removed under vacuum, and the residue was kept under
vacuum for 30 min. It was dissolved in the minimum amount
of CH2Cl2 and crystallized by diffusion of a hexanes layer.
Yield: 8 mg (0.012 mmol, 26%) of brownish-red crystals. IR
Ack n ow led gm en t. This work was supported by
Universidad Cato´lica de Valpara´ıso (DI-125.710/99) and
FONDECYT-Chile (Grant 1990788). F.G. acknowledge
CONICYT for a doctoral fellowship and FONDECYT
(Proyect 2010033). We are also thankful for the finan-
cial support of Fundacio´n Andes (Convenio C-13672),
MECESUP (Proyecto UCO 9905), and Red Ibero-
americana de Cata´lisis Homoge´nea. Zaragoza’s
group acknowledge the financial support from DGI
(Project BQU2002-1729). The loan of NH4ReO4 from
MOLYMET-Chile is also very appreciated.
1
(CH2Cl2, ν(CO), cm-1): 2022(vs), 1953(s). H NMR (CDCl3) δ:
2.20 (m, 2H, -CH2-), 2.23 (s, 6H, CH3), 2.26 (s, 6H, CH3), 2.40
(m, 2H, -CH2-), 5.06 (m, 2H, -CHdCH2), 5.78 (m, 1H, -CHd
CH2). MS (EI, based on 187Re) m/z: 672 [M+], 644 [M+ - CO],
545 [M+ - I], 517 [M+ - I - CO].
Su p p or tin g In for m a tion Ava ila ble: Bond lengths and
interbond angles, anisotropic displacement coefficients, and
all atom coordinates and thermal parameters for complexes
Str u ctu r a l Deter m in a tion of Com p lexes 8a a n d 9b.
Crystals of 8a and 9b suitable for X-ray diffraction studies
were obtained by recrystallization from hexanes solutions by
slow cooling to -18 °C. A summary of crystal data, data
collection, and refinement parameters for the structural
analyses is given in Table 2. A colorless (8a ) or a white crystal
(9b) was glued to a glass fiber and mounted on a Bruker
SMART APEX diffractometer, equipped with a CCD area
detector. Data were collected using graphite-monochromated
Mo KR radiation (λ ) 0.71073 Å) and low-temperature equip-
ment (173 K for 8a and 100 K for 9b). Cell constants for 8a
were obtained from the least-squares refinement of three-
dimensional centroids of 4481 reflections in the range 4.80° e
2θ e 57.06° and from 5767 reflections in the region 5.04° e
1
8a and 9b in both CIF and tabular formats. H NMR spectra
for compounds 6a , 7b, 8b, 9a , and cis-(η5-C5Me4CH2CH2CHd
CH2)Re(CO)2I2. This material is available free of charge via
the Internet at http://pubs.acs.org.
OM030443M
(44) Blessing, R. H. Acta Crystallogr. Sect. A 1995, 51, 33.
(45) SAINT+, version 6.01; Bruker AXS, Inc.: Madison, WI, 2000;
and SAINT, version 4.0.
(46) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1997.