Synthesis of novel chiral cyclopentadienes: synthesis of chiral iron complexes and the crystal structures of compund (8) and [(η5-C5(Me)4C(H)(CH3)(C 2H5))Fe(CO)-(η4-diphenylbutad

Article abstract of DOI:10.1021/om950958g

Two new functionalized tetramethylcyclopentadiene (FTMCP) ligands are described: optically active (1S)-1-(6-methoxynaphthalenyl)-1-(2,3,4,5-tetramethylcyclopentadienyl)ethane (2) and racemic 1-methyl-1-(2,3,4,5-TMCP)propane (3). These ligands were used to

Full text of DOI:10.1021/om950958g

2638
Organometallics 1997, 16, 2638-2645
Syn th esis of Novel Ch ir a l Cyclop en ta d ien es: Syn th esis
of Ch ir a l Ir on Com p lexes a n d th e Cr ysta l Str u ctu r es of
[(η5-(1S)-1-(6-m eth oxyn a p h th a len yl)-1-(tetr a m eth yl-
cyclop en ta d ien yl)eth a n e)F e(CO)2Sn Cl3] a n d
[(η5-C5(Me)4C(H)(CH3)(C2H5))F e(CO)-
(η4-d ip h en ylbu ta d ien e)]+[BF 4]-
Patrick McArdle,* Alan G. Ryder, and D. Cunningham
Chemistry Department, University College Galway, Galway, Ireland
Received December 14, 1995X
Two new functionalized tetramethylcyclopentadiene (FTMCP) ligands are described:
optically active (1S)-1-(6-methoxynaphthalenyl)-1-(2,3,4,5-tetramethylcyclopentadienyl)-
ethane (2) and racemic 1-methyl-1-(2,3,4,5-TMCP)propane (3). These ligands were used to
synthesize cationic diene complexes [(η5-FTMCP)Fe(CO)(η4-diene)]+[BF4]- (diene ) diphen-
ylbutadiene (11), methyl hexa-2,4-dienoate (10)). The absolute configuration of the ligand
2 was determined from the crystal structure of complex [(η5-(1S)-1-(6-methoxynaphthalenyl)-
1-(2,3,4,5-tetramethylcyclopentadienyl)-ethane)Fe(CO)2SnCl3] (8).
In tr od u ction
able 1,3-dicarbonyl compounds and successive acid-
catalyzed cyclization can also be used to prepare tetra-
and pentaalkylated cyclopentadienyl ketones and car-
boxylic acids.14 Cesarotti et al.1,15,16 reported the syn-
thesis of chiral 1-menthyl-2,3,4,5-tetramethylcyclopen-
tadiene, with lithium tetramethylcyclopentadienide as
the starting material. Phosphine-substituted FTMCP
ligands can also be synthesized by this route.17
Despite the widespread use of the pentamethylcyclo-
pentadienyl (PMCP) ligand in transition-metal chem-
istry, there have been comparatively few studies de-
scribing the synthesis and use of functionalized tetra-
methylcyclopentadiene (FTMCP) ligands. Recently,
however, interest has been generated in these types of
ligands for use in asymmetric synthesis, catalysis,
inorganic polymers, and as heterodifunctional ligands.1-8
A recent review by Halterman9 gives an overview of
chiral cyclopentadienes and their uses in organometallic
chemistry.
A comprehensive range of FTMCP ligands can be
synthesized by adopting procedures developed for syn-
thesizing PMCP. Feitler and Whitesides10 included a
synthesis for 1-ethyl-2,3,4,5-tetramethylcyclopentadiene
(1-Et-2,3,4,5-TMCP) in their examination of synthetic
routes to PMCP. The use of 2,3,4,5-tetramethylcyclo-
pent-2-enone enolate and pentamethylfulvene as pre-
cursors to FTMCP ligands was explored by Mintz and
co-workers.11-13 The electrophilic allylation of enolyz-
Perhaps the most practical and efficient route to
FTMCP ligands is that of Threlkel and Bercaw,18 which
is based on the reaction of 2-butenyllithium with esters.
By adapting the above synthesis and using an optically
active ester,19 Dormond synthesized an optically pure
pentaalkylcyclopentadiene, 1-phenyl-1-(2,3,4,5-tetra-
methylcyclopentadienyl)propane.20 Conversion of the
ligand to its lithium salt by reaction with n-butyllithium
and subsequent reaction with TiCl4 yielded a titanyl
complex in >99% ee. The optically pure dimeric mo-
lybdenum complex [(C5(CH3)4C*(H)(Ph)(C2H5))Mo(CO)3]2
was also described.
In this report we describe the effective synthesis of a
new optically active FTMCP ligand using the 2-bute-
nyllithium/ester procedure of Threlkel and Bercaw, but
which employs the relatively inexpensive optically active
ester of naproxen (ethyl (6-methoxy-R-methyl-2-naph-
thalenyl)acetate).
X Abstract published in Advance ACS Abstracts, May 15, 1997.
(1) Schofield, P. A.; Adams, H.; Bailey, N. A.; Cesarotti, E. J .
Organomet. Chem. 1991, 412, 273.
(2) Conticello, V. P.; Brard, L.; Giardello, M. A.; Tsuji, Y.; Sabat,
M.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1992, 114, 2761.
(3) Conticello, V. P.; Brard, L.; Giardello, M. A.; Rheingold, A. L.;
Sabat, M.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1994, 116,
10212.
(4) Gibson, C. P.; Bem, D. S.; Falloon, S. B.; Hitchens, T. K.;
Cortopassi, J . E. Organometallics 1992, 11, 1742.
(5) Moran, M.; Pascual, M. C.; Cuadrado, I.; Losada, J . Organome-
tallics 1993, 12, 811.
The synthesis of cationic iron diene complexes [(η5-
PMCP)Fe(CO)(η4-diene)]+ in high yield21-24 has previ-
(13) Bensley, D. M.; Mintz, E. A.; Sussangkarn, S. J . J . Org. Chem.
1988, 53, 4417.
(6) Okuda, J .; Zimmermann; K. H. J . Organomet. Chem. 1988, 344,
C1.
(7) Okuda, J .; Zimmermann, K. H.; Herdtweck, E. Angew. Chem.,
Int. Ed. Engl. 1991, 30, 430.
(14) Koschinsky, R.; Ko¨hl, T. P.; Mayr, H. Tetrahedron Lett. 1988,
29, 5641.
(15) Cesarotti, E.; Hugo, R.; Kagan, H. B. Angew. Chem., Int. Ed.
Engl. 1979, 18, 779.
(8) Hashimoto, H.; Tobita, H.; Ogino, H. Organometallics 1993, 12,
2182.
(9) Halterman, R. L. Synthesis and Applications of Chiral Cyclo-
pentadienyl Complexes. Chem. Rev. 1992, 92, 965.
(10) Feitler, D.; Whitesides, G. M. Inorg. Chem. 1976, 15, 466.
(11) Mintz, E. A.; Pando, J . C.; Zervos, I. J . Org. Chem. 1987, 52,
2948.
(16) (a) Cesarotti, E.; Hugo, R.; Vitiello, R. J . Mol. Catal. 1981, 12,
63. (b) Garner, C. M.; Prince, M. E. Tetrahedron Lett. 1994, 35, 2463.
(17) Casey, C. P.; Bullock, R. M.; Nief, F. J . Am. Chem. Soc. 1983,
105, 7574.
(18) Threlkel, R. S.; Bercaw, J . E. J . Organomet. Chem. 1977, 136,
1.
(19) Weidmann, R.; Horeau, A. Bull. Soc. Chim. Fr. 1967, 117.
(20) Dormond, A.; Bouadili, A. El.; Moise, C. Tetrahedron Lett. 1983,
24, 3087.
(12) Bensley, D. M.; Mintz, E. A. J . Organomet. Chem. 1988, 353,
93.
S0276-7333(95)00958-7 CCC: $14.00 © 1997 American Chemical Society

Novel Chiral Cyclopentadienes
Organometallics, Vol. 16, No. 12, 1997 2639
F igu r e 1. Synthesis of cationic diene complexes of iron.
F igu r e 2. Synthesis of (1S)-(-)-1-(6-methoxynaphtha-
lenyl)-1-(2,3,4,5-tetramethylcyclopentadienyl)ethane.
F igu r e 3. Synthesis of iron carbonyl complexes using
FTMCP ligands.
ously been reported by this laboratory (Figure 1). Here
we describe the effect of introducing a chiral group on
the cyclopentadienyl ring. The reaction of these new
cationic diene complexes with nucleophiles is also
examined.
or by vacuum distillation at low temperature (<60 °C).
The ligand, 3, was not characterized but was reacted
directly with Fe(CO)5 to yield the dimer [(η5-1-methyl-
1-(2,3,4,5-tetramethylcyclopentadienyl)propane)Fe-
(CO)2]2 (5), which was fully characterized. Complex 5
was also characterised crystallographically.26
Resu lts a n d Discu ssion
Liga n d Syn th esis. The reaction of 2-butenyllithium
with the optically pure (2S)-(+)-2-(6-methoxynaphtha-
lenyl)ethyl propionate (1; the ethyl ester of Naproxen)
proceeds in a straightforward manner yielding the
optically active (1S)-(-)-1-(6-methoxynaphthaleneyl-1-
(2,3,4,5-tetramethylcyclopentadienyl)ethane (2) in 60%
yield (Figure 2). However, close attention to detail and
absolutely anhydrous conditions are necessary for op-
timum yield. The product 2 is a mixture of isomers
which differ in the position of the hydrogen atom
attached to the cyclopentadienyl ring. Because of the
large number of isomers 1H NMR spectra were very
complex and characterization of the product using NMR
was not possible. Analytically pure (2) exhibited an
optical rotation of [R]D20 ) -66° (c ) 1, CHCl3). This is
opposite in sign to the starting ester 1; however, this
does not necessarily indicate inversion since the sodium
salt of the parent naproxen also has a negative rotation
and yet maintains the same absolute configuration. The
ligand 2 is air-stable when pure and can be stored at
room temperature for months without any sign of
decomposition.
Syn th esis of Ir on Com p lexes. Synthesis of the
dimers [(η5-(1S)-1-(6-methoxynaphthalenyl)-1-(2,3,4,5-
tetramethylcyclopentadienyl)ethane)Fe(CO)2]2 (4) and
[(η5-1-methyl-1-(2,3,4,5-tetramethylcyclopentadienyl)-
propane)Fe(CO)2]2 (5) was carried out by reacting the
appropriate ligand 2 or 3 with Fe(CO)5 in ethylbenzene
under reflux under an inert atmosphere (Figure 3). This
is a modification of the procedure of King et al.25 and
has also been used successfully in this laboratory for
the synthesis of the [(PMCP)Fe(CO)2]2 dimer. The
reaction times required for 2 and 3 are only slightly
longer than that required for the reaction of PMCP with
Fe(CO)5 (22 h vs 16 h).21,22 The dimers crystallized from
the reaction mixture, and the crude products were
converted to the dicarbonyl iodides (6, 7) without
further purification. The dimers are stable in the solid
form but decompose in solution when exposed to the
atmosphere. The iodides, being air-stable, were easier
to purify than the dimers. Excessive heating of the
iodide [(η5-(1S)-1-(6-methoxynaphthalenyl)-1-(2,3,4,5-
tetramethylcyclopentadienyl)ethane)Fe(CO)2I] (6) was
found to result in racemization, which was discovered
when the crystal structure of the iodide 6 was solved in
a centric space group.26 The very dark colors of the
dimers and iodides made direct determination of their
optical rotation by conventional polarimetry impossible.
For this reason the iodide 6 was converted to the SnCl3
derivative (η5-(1S)-1-(6-methoxynaphthalenyl)-1-(2,3,4,5-
tetramethylcyclopentadienyl)ethane)Fe(CO)2SnCl3 (8),
which was lighter in color and more crystalline. The
overall yield of 8 was 64%, obtained as analytically pure
crystals. All the crystals had the same morphology, and
The synthesis of the racemic 1-methyl-1-(2,3,4,5-
tetramethylcyclopentadienyl)propane (3) was achieved
by the reaction of 2-butyllithium with 2,3,4,5-tetra-
methylcyclopent-2-enone in anhydrous pentane followed
by acid hydrolysis. The crude product is a viscous oil
which can be purified either by column chromatography
(21) Mahon, M. F. Ph.D. Thesis, National University of Ireland,
1987.
(22) MacHale, D. Ph.D. Thesis, National University of Ireland, 1991.
(23) McArdle, P.; McHale, D.; Mahon, M.; Cunningham, D. J .
Organomet. Chem. 1990, 381, C13.
(24) Hynes, M. J .; Mahon, M.; McArdle, P. A. J . Organomet. Chem.
1987, 320, C44.
(25) King, R. B.; Bisnette, M. B. J . Organomet. Chem. 1967, 8, 287.
(26) Ryder, A. G. Ph.D. Thesis, National University of Ireland, 1993.

2640 Organometallics, Vol. 16, No. 12, 1997
McArdle et al.
Ta ble 1. Com p a r ison of 13C NMR Sp ectr a (p p m )
for Ir on Ca r bon yl Com p lexes
establish conclusively the correct assignment for the
ring carbons.
The synthesis of the cationic diene complex [(η5-1-
methyl-1-(2,3,4,5-tetramethylcyclopentadienyl)propane)-
Fe(CO)(η4-methyl hexa-2,4-dienoate)]+[BF4]- (10) was
based on Reger and Coleman’s method for Cp com-
plexes,29 which was adapted in this laboratory20-24 for
4a
5
6
7
10a
11a
C(3-7) 102.1
100.27
104.02 99.4 100.3 105.7/105.3 102.98
98.32 98.6
97.83 97.5
97.63 92.32 96.3
96.81
31.45 36.3
97.56 102.7/102.3 99.2
100
99.53
96.84
97.12 101/99.4
98.7/98
94.28 97.8/98.4
32.14 32.2/32
20.63 19/18.6
11.33 10.3
98.5
94.75
94.37
32.05
18.3
the synthesis of PMCP cationic diene complexes.
A
C(8)
C(13)
35.65
22.43
shorter route was employed for the synthesis of [(η5-1-
methyl-1-(2,3,4,5-tetramethylcyclopentadienyl)propane)-
Fe(CO)(diphenylbutadiene)]+[BF4]- (11) in which the
dimer 5 was reacted directly with AgBF4 in THF to
generate the THF cation [(η5-1-methyl-1-(2,3,4,5-tetra-
methylcyclopentadienyl)propane)Fe(CO)2(THF)]+[BF4]-
(9). Subsequent irradiation of this THF-substituted
cation with diphenylbutadiene in dichloromethane for
46 h yielded the cationic diene 11. This procedure
eliminates the need to synthesize and purify the dicar-
bonyl iodide complex 7.
20.0
22.2
C(9-12) 11.69
10.06 12.1
9.11 10.9
7.97 10.6
(1:1:2) 10.0
9.34
8.74
8.29
(1:1:2)
11.07
10.57
10.19
9.9
9.4
9.3
8.83
a
4, 10, and 11 were recorded in CDCl3, all others in CS2.
The cationic diene complex 10 was isolated as a
mixture of diastereoisomers (four isomers are possible:
RCpRFe, RCpSFe, SCpSFe, and SCpRFe), because the methyl
hexa-2,4-dienoate ligand can bond to the iron in two
different orientations relative to the FTMCP ligand. All
attempts at separating the diastereoisomers (even
partially) by multiple recrystallization failed. The
proton NMR spectra of the cationic diene complexes
were poorly resolved due to slight contamination with
traces of paramagnetic impurities which could not be
removed, even after 5-10 recrystallizations. 13C NMR
spectra were resolved, however, and it is possible to see
that the methyl hexa-2,4-dienoate ligand in complex 10
is bound to the iron atom in both possible orientations
to yield a mixture of isomers in equal proportions. The
NMR spectra do not show all the peaks for the four
possible isomers because the RCpRFe and SCpSFe isomers
are enantiomers, as are the RCpSFe, SCpRFe pair. There-
fore, NMR will only show two sets of signals, and these
are given in Table 1. If the methyl hexa-2,4-dienoate
ligand had bound to the iron atom in complex 10 in only
one orientation, then the NMR spectra would only show
a single set of resonances for the cyclopentadienyl ring
carbons C(3-7); however, this is not the case. Two
resonances are observed for each of the diene carbons
C(2A) and C(5A) in 13C NMR spectra of complex 10.
Attempts to prepare analogous cationic diene com-
plexes using the η5-(1S)-1-(6-methoxynaphthalenyl)-1-
(2,3,4,5-tetramethylcyclopentadienyl)ethane ligand 2
have not been successful due to difficulties in separation
and purification of the reaction products.
Nucleophilic attack at the coordinated η4-diene of 10
with sodium methoxide in methanol yields the neutral
red oil 12 as the only product, (Figure 5). The complex
12 decomposes slowly when exposed to the atmosphere,
and accurate microanalytical data could not be obtained.
Characterization of the product by NMR and IR spec-
troscopy (and comparison with the PMCP analogue,
which had been fully characterized previously in this
laboratory23) showed it to be the η3-allyl complex [(η5-
1-methyl-1-(2,3,4,5-tetramethylcyclopentadienyl)propane)-
Fe(CO)(η3-C8H13O3)] (12), isolated as a mixture of
diastereoisomers. It was not possible to separate the
various diastereoisomers. As in the case of the PMCP
analogue, nucleophilic attack takes place at the terminal
F igu r e 4. Labeling scheme for NMR spectra of the
FTMCP complexes.
one of these was used for the structure determination.
Optical rotation measurements using solutions of these
20
crystals gave [R]D ) -31 ( 2°, c ) 1, CHCl3. The
crystal structure of 8, (Figure 6) determined the abso-
lute structure and showed that the configuration at the
chiral center (S) was retained. Unfortunately it was not
possible to obtain good-quality NMR spectra of this
compound. The carbonyl bands for 8 are at 2026 and
1986 cm-1 in dichloromethane solution, which compares
to 1974 and 1923 cm-1 for [(PMCP)Fe(CO)2Sn(Ph)3].27
The large difference is due to the stronger electron-
withdrawing effect of the SnCl3 group. A similar result
has been reported for the Cp analogues [(Cp)Fe(CO)2-
Sn(Cl)3] and [(Cp)Fe(CO)2Sn(Ph)3], the values for which
are 2048, 2008 and 2048, 2008 cm-1, respectively.28
The primary features of the NMR spectra of the
dimers and the iodide complexes are the signals due to
the pentasubstituted cyclopentadienyl ligand. The in-
troduction of a chiral substituent (whether racemic or
resolved) lowers the symmetry of the Cp ring, therefore,
separate signals are observed in the proton spectrum
for each of the four methyl groups. In the 13C spectra
individual signals for the five ring carbons and the four
attached methyl groups are also seen. The 13C results
are summarized in Table 1.
For complexes with the η5-(1S)-1-(6-methoxynaph-
t h a len yl)-1-(2,3,4,5-t et r a m et h ylcyclopen t a dien yl)
ethane ligand the naphthyl ring induces a downfield
shift of ∼4 ppm of the signal of the chiral carbon C(8)
in the 13C spectra of complexes 4 and 6 because of its
greater electron-withdrawing effect Figure 4. The effect
is reduced at C(13) (the methyl group attached to C(8))
but is still an appreciable 2 ppm. The effect of the
naphthyl ring on the position of individual ring carbons
is not easily ascertained because it is not possible to
(27) King, R. B.; Douglas, W. M.; Efraty, A. J . Organomet. Chem.
1974, 69, 131.
(28) Dalton, J .; Paul, I.; Stone, F. G. A. J . Chem. Soc. A 1969, 2744.
(29) Reger, D. L.; Coleman, C. J . Organomet. Chem. 1977, 131, 153.

Novel Chiral Cyclopentadienes
Organometallics, Vol. 16, No. 12, 1997 2641
Ta ble 2. Selected Bon d Len gth s (Å) for [(η5-(1S)-
1-(6-m eth oxyn a p h th a len yl)-1-(2,3,4,5-tetr a m eth yl-
cyclop en ta d ien yl)eth a n e)F e(CO)2Sn Cl3] (8)
Sn(1)-Cl(3)
Sn(1)-Cl(2)
Sn(1)-Cl(1)
Sn(1)-Fe(1)
Fe(1)-C(2)
Fe(1)-C(1)
Fe(1)-C(3)
Fe(1)-C(4)
Fe(1)-C(7)
Fe(1)-C(6)
Fe(1)-C(5)
O(1)-C(1)
O(2)-C(2)
2.371(2)
2.375(2)
2.3908(12)
2.4698(6)
1.778(4)
1.784(4)
2.094(3)
2.104(4)
2.113(4)
2.122(3)
2.128(4)
1.131(6)
1.141(6)
C(3)-C(4)
C(3)-C(7)
C(3)-C(8)
C(4)-C(5)
C(4)-C(9)
C(5)-C(6)
C(5)-C(10)
C(6)-C(7)
C(6)-C(11)
C(7)-C(12)
C(8)-C(14)
C(8)-C(13)
1.436(5)
1.438(4)
1.505(5)
1.422(5)
1.510(5)
1.419(6)
1.495(6)
1.455(5)
1.509(5)
1.494(5)
1.518(5)
1.521(6)
Ta ble 3. Selected Bon d An gles (d eg) for [(η5-(1S)-
1-(6-m eth oxyn a p h th a len yl)-1-(2,3,4,5-tetr a m eth yl-
cyclop en ta d ien yl)eth a n e)F e(CO)2Sn Cl3] (8)
Cl(3)-Sn(1)-Cl(2)
Cl(3)-Sn(1)-Cl(1)
Cl(2)-Sn(1)-Cl(1)
Cl(3)-Sn(1)-Fe(1) 115.34(5) C(6)-C(5)-C(10)
Cl(2)-Sn(1)-Fe(1) 126.17(4) C(4)-C(5)-C(10)
Cl(1)-Sn(1)-Fe(1) 116.34(4) C(10)-C(5)-Fe(1)
C(2)-Fe(1)-C(1)
C(2)-Fe(1)-C(3)
C(1)-Fe(1)-C(3)
C(2)-Fe(1)-Sn(1)
C(1)-Fe(1)-Sn(1)
O(1)-C(1)-Fe(1)
O(2)-C(2)-Fe(1)
C(4)-C(3)-C(8)
C(7)-C(3)-C(8)
C(8)-C(3)-Fe(1)
96.42(8) C(5)-C(4)-C(9)
100.29(7) C(3)-C(4)-C(9)
97.58(5) C(9)-C(4)-Fe(1)
126.0(4)
124.7(4)
128.7(3)
126.4(4)
125.5(4)
131.7(3)
126.7(4)
124.1(4)
130.7(3)
130.0(3)
123.1(3)
129.0(3)
110.2(3)
117.3(3)
94.1(2)
101.5(2)
104.1(2)
92.4(2)
C(5)-C(6)-C(11)
C(7)-C(6)-C(11)
C(11)-C(6)-Fe(1)
C(3)-C(7)-C(12)
C(6)-C(7)-C(12)
C(12)-C(7)-Fe(1)
C(3)-C(8)-C(14)
C(3)-C(8)-C(13)
F igu r e 5. Nucleophilic attack on cationic diene 10 showing
the atom labels of the η4-diene ligand for NMR spectra.
88.6(2)
176.0(5)
175.3(5)
122.0(3)
130.0(3)
128.9(2)
C(14)-C(8)-C(13) 110.8(3)
logues that have been reported by Greene et al.30-34
Table 4 gives a comparison of bond lengths and angles
between 8 and two of its Cp analogues. The Fe-Sn
bond lengths are virtually identical, while the tin-
chloride bonds are slightly longer in complex 8. In addi-
tion the iron-FTMCP carbon bond lengths are longer
than those for the Cp compound. This is expected, as
the increased steric pressure of the five substituents
would force the ring farther away from the iron atom.
Also evident is the trans influence of the CO ligands,
with the two Fe-Cp bonds trans to the carbonyls being
longer than the other three by ∼0.01-0.03 Å.
The Sn atom is in a distorted-tetrahedral environment
with Cl-Sn-Cl angles of 96-100° and Cl-Sn-Fe
angles in the range 115-126° (Table 2). Curiously, one
of the Sn-Cl bonds is slightly longer than the other two
in both complex 8 and CpFe(CO)2‚SnCl3 (Table 3). This
effect is not present in the CpFe(CO)2SnBr3 complex.
The structure of 11 is shown in Figure 7. The high
value of the R index in the structure of the cationic diene
complex [(η5-C5(Me)4C(H)(CH3)(C2H5))Fe(CO)(diphen-
ylbutadiene)]+[BF4]- (11) is probably due to the prob-
F igu r e 6. ORTEX drawing of complex 8 with hydrogens
omitted (20% probability).
carbon C(5A) of the η4-diene. Nucleophilic attack is
directed to the C(5A) carbon by a combination of the
directing effect of the carbomethoxy group and relief of
-
lems associated with the disordered BF4 anion. The
four fluorines were each disordered over two sites (with
occupancies of 70% and 30%), which generated distorted
cubic geometry about the boron. However, despite these
problems the standard deviations of the bond lengths
and angles in the cation are quite good.
1
steric strain.23 The H and 13C NMR spectra of 12 are
complex and indicate the presence of two sets of dias-
tereoisomers. The diene carbons C(2A-5A) all show
two resonances, which confirms that the diene ligand
is bound to the iron in both possible orientations in a
1:1 ratio. It is clear that the chiral substituent on the
cyclopentadienyl ring does not control the coordination
of the η4-diene in the formation of 10.
(30) Bryan, R. F. J . Chem. Soc. A 1967, 192.
(31) Greene, P. T.; Bryan, R. F. J . Chem. Soc. A 1970, 1696.
(32) Greene, P. T.; Bryan, R. F. J . Chem. Soc. A 1970, 2261.
(33) Melson, G. A.; Stokely, P. F.; Bryan, R. F. J . Chem. Soc. A 1970,
2247.
(34) Zubieta, J . A.; Zuckermann, J . J . Structural Tin Chemistry.
Prog. Inorg. Chem. 1978, 24, 340.
Descr ip tion of Str u ctu r es. The structure of the tin
derivative 8 is similar to the structures of the Cp ana-

2642 Organometallics, Vol. 16, No. 12, 1997
McArdle et al.
Ta ble 4. Com p a r ison of Bon d Len gth s a n d Bon d An gles for Com p lex 8 a n d Tw o Cp An a logu es
bond lengths (Å)
and angles (deg)
32
34
8
CpFe(CO)2‚SnCl3
CpFe(CO)2‚SnBr3
Fe-Sn
2.4698(6)
1.784(4)
1.778(4)
2.467(1)
1.785(6)
1.785(6)
2.462(2)
1.768(12)
1.747(13)
Fe-C(1)
Fe-C(2)
Sn-X
Cl(1) ) 2.3908(12)
Cl(2) ) 2.375(2)
Cl(3) ) 2.371(2)
C(3) ) 2.094(3)
C(4) ) 2.104(4)
C(5) ) 2.128(4)
C(6) ) 2.122(3)
C(7) ) 2.113(4)
88.6(2)
Cl(1) ) 2.373(2)
Cl(2) ) 2.350(2)
Cl(3) ) 2.358(2)
C(3) ) 2.088(7)
C(4) ) 2.109(6)
C(5) ) 2.089(7)
C(6) ) 2.086(6)
C(7) ) 2.087(6)
90.0(2)
Br(1) ) 2.505(2)
Br(2) ) 2.491(2)
Br(3) ) 2.508(2)
C(3) ) 2.08(1)
C(4) ) 2.09(2)
C(5) ) 2.07(2)
C(6) ) 2.11(1)
C(7) ) 2.09(2)
92.0(4)
Fe-C(ring)
Sn-Fe-C(1)
Sn-Fe-C(2)
C(1)-Fe-C(2)
92.4(2)
94.1(2)
91.1(2)
94.9(3)
88.5(4)
96.0(6)
Ta ble 5. Selected Bon d Len gth s (Å) for 11
Fe(1)-C(17)
Fe(1)-C(3)
Fe(1)-C(2)
Fe(1)-C(22)
Fe(1)-C(18)
Fe(1)-C(19)
Fe(1)-C(21)
Fe(1)-C(20)
Fe(1)-C(4)
Fe(1)-C(1)
O(1)-C(17)
C(1)-C(2)
1.776(5)
2.064(5)
2.072(4)
2.083(5)
2.098(4)
2.121(4)
2.128(5)
2.133(4)
2.258(5)
2.282(4)
1.139(6)
1.390(7)
1.453(7)
1.401(7)
1.397(6)
1.477(7)
C(5)-C(6)
1.422(7)
1.398(7)
1.424(6)
1.445(7)
1.498(7)
1.414(7)
1.506(7)
1.422(6)
1.494(7)
1.414(7)
1.482(7)
1.509(6)
1.503(8)
1.522(7)
1.498(9)
C(11)-C(12)
C(18)-C(19)
C(18)-C(22)
C(18)-C(23)
C(19)-C(20)
C(19)-C(27)
C(20)-C(21)
C(20)-C(28)
C(21)-C(22)
C(21)-C(29)
C(22)-C(30)
C(23)-C(24)
C(23)-C(25)
C(25)-C(26)
C(1)-C(5)
C(2)-C(3)
C(3)-C(4)
C(4)-C(11)
Ta ble 6. Selected Bon d An gles (d eg) for 11
C(17)-Fe(1)-C(3)
114.8(2) C(1)-C(2)-Fe(1)
113.9(2) C(3)-C(2)-Fe(1)
39.6(2) C(4)-C(3)-C(2)
87.5(2) C(4)-C(3)-Fe(1)
87.6(2) C(2)-C(3)-Fe(1)
82.7(2) C(3)-C(4)-Fe(1)
37.4(2) O(1)-C(17)-Fe(1)
69.1(2) C(19)-C(18)-C(23) 129.3(4)
81.2(2) C(22)-C(18)-C(23) 123.5(4)
68.3(2) C(18)-C(23)-C(24) 118.0(5)
36.8(2) C(18)-C(23)-C(25) 108.2(5)
79.8(2) C(24)-C(23)-C(25) 114.3(5)
63.3(2) C(26)-C(25)-C(23) 112.5(6)
122.4(4)
79.8(3)
C(17)-Fe(1)-C(2)
C(3)-Fe(1)-C(2)
C(17)-Fe(1)-C(22)
C(17)-Fe(1)-C(18)
C(17)-Fe(1)-C(4)
C(3)-Fe(1)-C(4)
C(2)-Fe(1)-C(4)
C(17)-Fe(1)-C(1)
C(3)-Fe(1)-C(1)
C(2)-Fe(1)-C(1)
C(4)-Fe(1)-C(1)
C(2)-C(1)-Fe(1)
C(1)-C(2)-C(3)
69.9(3)
123.3(5)
78.9(3)
70.5(3)
63.8(3)
174.2(5)
F igu r e 7. ORTEX drawing of complex 11.
The structure shows that 11 crystallized in an exo
configuration with the CO ligand lying symmetrically
out of the face of the coordinated diene. The coordina-
tion geometry is approximately distorted tetrahedral if
the Cp ring and carbonyl ligands occupy a single site
each and the diene ligand is bidentate. The C(H)(CH3)-
(C2H5) substituent of the ring is oriented syn to the
carbonyl ligand with the ethyl group of the chiral
substituent pointing up above the plane of the Cp ring.
The methyl and hydrogen attached to C(23) are there-
fore directed downward below the plane to minimize
steric strain. The bond lengths Fe-C(22) (2.083(5) Å)
and Fe-C(18) (2.098(4) Å) (see Table 5) are the shortest
of the Fe-ring carbon bonds. When viewed from above
the plane of the Cp ring, the CO group is staggered with
respect to the ring substituents attached to C(22) and
to C(18). As in the previous structure (of complex 8) it
seems that the trans influence of the carbonyl ligand
dominates over the steric effect of the C(H)(CH3)(C2H5)
substituent, causing the trans iron-Cp ring bonds to
be lengthened. A similar effect is also visible in the
structure of [(η5-PMCP)Fe(CO)(methyl hexa-2,4-dieno-
ate)]+[BF4]-,23 where the Fe-C(10) bond length is also
short (2.106(14) Å).
of the η4-diene unit of 11 have Fe-C bonds that are
shorter than the outer ones, but in this case by a larger
margin (∼0.19 Å vs ∼0.15 Å).
Ma ter ia ls a n d P r oced u r es
All reactions were carried out under an atmosphere of dry
nitrogen or argon, using glassware that was dried for several
hours at 150 °C, before assembly under a stream of nitrogen
while still hot. All solvents were dried by standard methods.
Iron pentacarbonyl, 2-chlorobutane, and 2-bromo-2-butene
were obtained from Aldrich and used without further purifica-
tion. Naproxen was supplied by Roche Ireland Ltd. and used
as supplied.
1H and 13C NMR spectra were recorded on J EOL J NM-GX
270 and EX 90 FT NMR spectrometers. Microanalyses were
carried on a Perkin-Elmer 2400 CHN analyzer in the UCG
microanalytical laboratory. Optical rotation measurements
were made on a Perkin-Elmer 241 polarimeter. IR spectra
were recorded on Perkin-Elmer 983G and 1600FT-IR spec-
trometers. Spectra of liquid samples were taken as films and
those of solids in dichloromethane solution.
As observed in the structure of [(η5-PMCP)Fe(CO)-
(methyl hexa-2,4-dienoate)]+[BF4]-,23 the inner carbons
X-r a y Str u ctu r e Deter m in a tion . The structures was
solved by direct methods (SHELX8635) and refined by full-

Novel Chiral Cyclopentadienes
Organometallics, Vol. 16, No. 12, 1997 2643
Ta ble 7. Cr ysta llogr a p h ic Da ta a n d Str u ctu r e Refin em en t Deta ils for Com p lexes 8 a n d 11
empirical formula
fw
C30H35BF4FeO
554.24
C24H25Cl3FeO3Sn
642.33
cryst size, mm
temp, K
0.34 × 0.29 × 0.41
0.33 × 0.27 × 0.38
293(2)
293(2)
wavelength, Å
cryst syst
0.710 69
triclinic
0.710 69
orthorhombic
space group
unit cell dimens
P1h
P212121
a ) 9.527(2) Å, R ) 102.97(2)°,
a ) 12.3200(10) Å,
b ) 11.383(2) Å, â ) 96.67(2)°,
b ) 14.1150(10) Å,
c ) 14.345(2) Å, γ ) 112.48(2)°
c ) 15.002(2) Å
V, Å3
1365.1(4))
2608.8(4)
Z
2
4
density (calcd), Mg/m3
abs coeff, mm-1
1.348
0.601
1.635
1.843
F(000)
580
1280
θ range for data collection, deg
2.02-31.97
2.14-39.95
index ranges
0 e h e 10, -12 e k e 12, -14 e l e 14
0 e h e 22, 0 e k e 25, 0 e l e 27
9046
no. of rflns collected
no. of indep rflns
6991
6446 (R(int) ) 0.0151)
8761 (R(int) ) 0.0311)
refinement method
no. of data/restraints/params
Goodness of fit on F2 39
final R indices (I > 2σ(I))
R indices (all data)
largest diff peak and hole, e Å-3
abs structure param
full-matrix least squares on F2
6446/0/372
0.919
R1 ) 0.0805, wR2 ) 0.1915
R1 ) 0.1764, wR2 ) 0.2242
1.073 and -0.694
8761/0/291
0.965
R1 ) 0.0470, wR2 ) 0.1303
R1 ) 0.0848, wR2 ) 0.1450
1.608 and -0.905
-0.070(25)
matrix least squares using SHELXL-93.36 The data were
collected on an Enraf-Nonius CAD4 diffractometer. Data were
corrected for Lorentz and polarization effects but not for
absorption. Hydrogen atoms were included in calculated
positions with common thermal parameters. The non-hydro-
gen atoms were refined ansiotropically. All calculations were
carried out on a VAX 6610 computer. The ORTEX37 program
was used to obtain the drawings. The Flack parameter was
used to establish the absolute structure of complex 8.
poured carefully onto 200 cm3 of saturated aqueous NH4Cl,
the ether layer was separated, and the pH of the aqueous layer
adjusted to pH ∼9 with HCl. The aqueous layer was then
extracted with three portions of ether, and the combined ether
layers were dried over Na2SO4. After filtration the yellow
solution was concentrated by rotary evaporation.
The concentrate was dissolved in 30 cm3 of diethyl ether,
1.3 g of p-toluenesulphonic acid was added, and the mixture
was refluxed under argon for 10 min and then stirred at room
temperature for another 10 min before the solution was poured
onto a solution of 0.7 g of Na2CO3 in saturated aqueous
NaHCO3 (80 cm3). The aqueous layer was extracted three
times with ether, and the combined organic layers were dried
over Na2SO4. After filtration and evaporation of the ether a
waxy solid was obtained, which after double-recrystallization
from hot methanol was dried under vacuum to give 14.0 g
P r ep a r a tion of (2S)-(+)-2-(6-Meth oxyn a p h th a len yl)-
eth yl P r op ion a te (1). A 50 g amount of 6-methoxy-R-methyl-
20
2-naphthaleneacetatic acid (Naproxen; [R]D ) +66.1°, c ) 1,
CHCl3) was dissolved in 250 cm3 of dry, deoxygenated ethanol,
and after the addition of 2.64 g of H2SO4 the mixture was
refluxed under nitrogen for 5-6 h. The solution was then
cooled to room temperature slowly, during which time the ester
precipitated. The precipitate was filtered and then recrystal-
lized from hot methanol to yield a white crystalline product,
which was dried under high vacuum before use. The ester as
20
(60.8%) of the ligand as a pale beige powder. [R]D ) -66° (c
) 1, CHCl3). Anal. Calcd for C22H26O: C, 86.27; H, 8.50.
Found: C, 86.44; H, 8.74.
20
used had an optical rotation of [R]D ) +50° (c ) 1, CHCl3).
1-Me t h yl-1-(2,3,4,5-t e t r a m e t h ylcyclop e n t a d ie n yl)-
p r op a n e (3). This was prepared by the reaction of 2-butyl-
lithium with 2,3,4,5-tetramethylcyclopent-2-enone.
2-Butyllithium from 5.0 g (0.35 mol) of lithium wire and
32.41 g (0.35 mol) of 2-chlorobutane was added dropwise to
30.0 g (0.2174 mol) of 2,3,4,5-tetramethylcyclopent-2-enone
dissolved in 500 cm3 of pentane at 0 °C. After stirring at 0 °C
for 15 h 2-propanol was added to destroy any remaining
2-butyllithium.
The yellow solution was then poured onto 600 cm3 of water
(which had been acidified with 1 mL of HCl (concentrated) and
stirred for 2 h. The organic layer was separated, washed with
3 × 50 cm3 aliquots of saturated NaCl solution, and dried over
Na2SO4. Removal of solvent in vacuo gave a yellow oil, which
was chromatographed on neutral alumina using hexane as
eluant and evaporated to give crude 3 (28 g, 72%).
(1S)-(-)-1-(6-Met h oxyn a p h t h a len yl)-1-(2,3,4,5-t et r a -
m eth ylcyclop en ta d ien yl)eth a n e (2). A 2.1 g (0.30 mol)
amount of 0.5 mm lithium wire was placed directly into a dry
1 L (three-necked) flask under an argon atmosphere; 300 cm3
of anhydrous ether was then added. Under argon the reflux
condenser and pressure-equalizing dropping funnel containing
20 g (0.148 mol) of deoxygenated 2-bromo-2-butene were fitted.
After the reaction vessel was purged once more with argon,
2-3 cm3 of the halide was added all at once to initiate the
reaction. Once the mixture had begun to reflux gently, the
remainder of the halide was added dropwise at a rate which
maintained a gentle reflux. After complete addition of the
halide, the reaction mixture was stirred for an additional 1 h.
A 19.35 g (0.075 mol) amount of the ester 1 was dissolved
in the minimum amount of anhydrous diethyl ether (250 cm3),
deoxygenated and added dropwise to the lithium reagent with
constant stirring. The resulting pale green solution was then
Bis(µ-car bon yl)dicar bon ylbis(η5-(1S)-1-(6-m eth oxyn aph -
th alen yl)-1-(2,3,4,5-tetr am eth ylcyclopen tadien yl)eth an e)-
d iir on (4). A 5.0 g (16.34 mmol) amount of (1S)-(-)-1-(6-meth-
oxynaphthalene)-1-(2,3,4,5-tetramethylcyclopentadiene)-
ethane (2) and 9.6 g (49 mmol) of Fe(CO)5 were heated under
reflux in ethylbenzene for 22 h; this solution was cooled to
room temperature, filtered, and extracted with toluene. The
solvent was removed by slow evaporation to give the red-purple
solid 4 (6.28 g, 92%). It was not, however, possible to obtain
an analytically pure sample. IR (CH2Cl2 solution): ν(MC-O)
(35) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(36) Sheldrick, G. M. SHELXL-93: A Computer Program for Crystal
Structure Determination, University of Gottingen, Gottingen, Germany
1993.
(37) McArdle, P. J . Appl. Crystallogr. 1995, 28, 65.
(38) Gilman, H.; Zoellner, E. A.; Selby, W. M. J . Am. Chem. Soc.
1933, 55, 1252.
(39) R indices: R1 ) [∑||Fo| - |Fc||]/∑|Fo| (based on F); wR2 ) [[∑w
(|Fo - Fc |)2]/[∑w(Fo2)2]]1/2 (based on F2), w ) 1/[(σFo)2 + (0.1P)2].
2
2
Goodness of fit ) [∑w(Fo - Fc2)2/(Nobservns - Nparams)]1/2
.
1926, 1748 cm-1 1H NMR (90 MHz, CS2/TMS): δ 7.6-6.8
.
2

2644 Organometallics, Vol. 16, No. 12, 1997
McArdle et al.
(multiplet, 6H, naphthyl protons); 4.3 (quartet, 1H, C(8)-H);
3.82 (s, 3H, OCH3); 1.96 (s, 3H, vinyl Me); 1.84 (doublet, C(8)-
CH3); 1.79 (s, vinyl Me; this peak is coincident with half of
the doublet peak for the methyl group on the chiral center
C(8)-CH3); 1.30 (s, 3H, vinyl Me); 1.24 (s, 3H, vinyl Me). 13C
NMR (22.4 MHz, CDCl3/TMS): δ 157.41/140.64/133.1/129.21/
128.97/127.06/126.85/125.42/118.71/105.64 (C(14-23) naphthyl
ring carbons); 102.1/100.27/100/99.53/96.84 (C(3-7), cyclopen-
tadienyl carbons); 55.28 (C(24), OCH3); 35.65 (C(8)); 22.43
(C(13)); 11.69/8.74/8.29 (1:1:2, C(9-12), methyl's of TMCP). No
13CO resonances were observed.
solution was filtered and repeatedly recrystallized from dichlo-
romethane/petroleum ether (60-80 °C) by slow evaporation
until analytically pure yellow-green crystals were obtained
(0.75 g, 63.4% yield based on 6). The crystals, one of which
was used for X-ray crystallography, gave an optical rotation
20
of [R]D ) -31 ( 2° (c ) 1, CHCl3). Anal. Calcd for
C
24H25O2Cl3FeSn: C, 44.88; H, 3.92. Found: C, 44.35; H, 4.11.
IR (CH2Cl2 solution): ν(MC-O) 2026, 1986 cm-1
.
[(η5-C5(CH3)4C(H)(CH3)(C2H5))F e(CO)(m eth ylh exa -2,4-
d ien oa te)]+[BF 4]-(10). A 2.22 g (5.34 mmol) amount of the
iodide 7 and 1.04 g of AgBF4 were added to 30 cm3 of freshly
distilled THF under nitrogen and then stirred for 3 h (in the
dark). The solvent was removed in vacuo, and the THF cation
9 (ν(MC-O) 2045, 1997 cm-1 (CH2Cl2 solution)) was extracted
into 50 cm3 of dry dichloromethane and the extract filtered
through Celite to remove any silver residue. The solution was
transferred to a 100 cm3 three-necked flask equipped with a
reflux condenser. The solution was deoxygenated, 3.28 g of
methylhexa-2,4-dienoate was added, and the mixture was
irradiated with a 125 W medium-pressure Hg lamp with
constant stirring for 18 h, at which stage IR spectra showed
that complete reaction had occurred. The mixture was filtered,
concentrated to ∼5 cm3, and treated with diethyl ether to
precipitate the cation as an orange powder. Recrystallizations
from dichloromethane/hexane gave 10 (1.86 g, 69%) as a beige
powder. Anal. Calcd for C21H31O3BF4Fe: C, 53.20; H, 6.545.
Found: C, 53.23; H, 6.69. IR (CH2Cl2 solution): ν(MC-O)
2023 cm-1. IR (Nujol mull): 2021 (s), 1708 (s), 1315 (s), 1192
Bis(µ-ca r b on yl)d ica r b on ylb is(η5-1-m et h yl-1-(2,3,4,5-
tetr a m eth ylcyclop en ta d ien yl)p r op a n e)d iir on (5). 3 (10.0
g) and Fe(CO)5 (32.9 g) were used to give 5 by the method used
for 4 (11.79 g, 73%). The high solubility of this dimer in
hydrocarbon made recrystallization difficult, and it was used
without further purification. Analytically pure crystals were
grown by slow evaporation from a dichloromethane solution
using a stream of nitrogen gas. Anal. Calcd for C30H42O4Fe2:
C, 62.32; H, 7.27. Found: C, 62.45; H, 7.60. IR (CH2Cl2
solution): ν(MC-O): 1920, 1748 cm-1
.
1H NMR (270 MHz,
CS2/TMS): δ 2.53 (multiplet, 1H, C(8)-H); 1.70 (s, 3H, vinyl
Me); 1.56 (s, 3H, vinyl Me); 1.48 (s, 3H, vinyl Me); 1.34 (s, 3H,
vinyl Me); 1.327 (doublet, 3H, C(8)-CH3); 0.945 (triplet, 3H,
C(8)-CH2CH3). The CH2 signal (C(8)-CH2CH3) is broad and
coincident with the vinyl methyl peaks (∼1.6 ppm).
13C NMR (67.8 MHz, CS2/TMS): δ 104.02/98.32/97.83/97.63/
96.81 (C(3-7)); 31.45 (C(8)); 30.05 (C(14)); 20.0 (C(13)); 13.16
(C(15)); 10.06/9.11/7.97, (1:1:2, C(9-12), methyls of TMCP).
No 13CO resonances were observed.
(s), 1062 (s), 1034 (s), 764 (vw), 721 (s) cm-1
.
1H NMR (270
MHz, CDCl3/TMS): δ 6.21 (broad multiplet, 1H, (H(2) or H(3));
5.97 (broad multiplet, 1H, H(2) or H(3)); 3.7 (s, 3H, OCH3);
2.69 (broad multiplet, 1H, H(4)); 2.40 (broad multiplet, 1H,
H(1)); 2.20-1.6 (broad mass of peaks, vinyl methyls, C(8)-H
and C(8)-CH2), 1.4 (pair of doublets, J (CH3-H(4)) ) 6 Hz,
(C(8)-CH3); 1 (broad multiplet, 3H, C(8)-CH2CH3). 13C NMR
(67.8 MHz, CDCl3/TMS): δ 220.76 (CtO); 145.34 (CdO); 105.7/
105.3/102.7/102.3/101/99.4/98.7/98/97.8/96.4 (C(3-7)); 93 (C(4A),
C(3A)); 92.3/91.9 (C(5A)); 82.8/82.5 (C(2A)); 52.8/52.4 (C(OCH3));
32.2/32 (C(8)); 29.1 (C(14)); 19/18.6 (C(13)); 17/16.7 (CH3 of
methylhexa-2,4-dienoate); 13/12.6 (C(15)); 10.3/9.9/9.4/9.3 (C(9-
12)).
[(η5 -C 5 (C H 3 )4 C (H )(C H 3 )(C 2 H 5 ))F e (C O )(d i p h e n y l-
bu ta d ien e)]+[BF 4]-(11). A 2.22 g (3.84 mmol) amount of the
dimer 5 and 1.04 g of AgBF4 were added to 20 cm3 of THF,
and the mixture was stirred for 3 h under nitrogen. A 5.32 g
amount of diphenylbutadiene was added and the solution
irradiated for 46 h. The cation was isolated as a red-brown
microcrystalline solid (1.38 g, 32.6%). Crystals suitable for
X-ray analysis were grown by slow evaporation from a dichlo-
(η5-(1S)-1-(6-Me t h oxyn a p h t h a le n yl)-1-(2,3,4,5-t e t r a -
m eth ylcyclop en ta d ien yl)eth a n e)ir on Dica r bon yl Iod id e
(6). A 4.0 g (4.8 mmol) amount of dimer 4 and 2.44 g (9.6
mmol) of iodine in 15 cm3 of dry, degassed chloroform were
refluxed with constant stirring for 30 min; this solution was
cooled to room temperature and washed with
a sodium
thiosulfate solution (3 g in 10 cm3 of water). The organic layer
was separated, washed with water, and dried over Na2SO4.
The crude material was chromatographed on a neutral alu-
mina column using chloroform as eluant. On evaporation to
dryness 4.35 g (83%) of 6 was obtained as a dark brown solid.
Anal. Calcd for C24H25O3FeI: C, 52.96; H, 4.60. Found: C,
52.92; H, 4.65. IR (CH2Cl2 solution): ν(CO): 2019, 1972 cm-1
.
1H NMR (270 MHz, CDCl3/TMS): δ 7.55-6.96 (multiplet, 6H,
naphthyl ring protons); 3.95 (quartet, 1H, C(8)-H); 3.83 (s,
3H, OCH3); 2.14 (s, 3H, vinyl Me); 1.99 (s, 3H, vinyl Me); 1.95
(s, 3H, vinyl Me); 1.85 (s, 3H, vinyl Me); 1.77 (doublet, 3H,
C(8)-CH3). 13C NMR (67.8 MHz, CS2/TMS): δ 215.2/215
(CtO); 157.3/138.31/128.7/128.5/127/126.1/125/119.1/105.2
(C(14-23)); 99.4/98.6/97.5/92.32 (C(3-7)); 54.5 (C(24), OCH3);
36.3 (C(8)); 22.2 (C(13)); 12.1, 10.9, 10.6, 10.0 (C(9-12),
methyls on TMCP).
romethane solution under
Calcd for C30H35OBF4Fe: C, 65.02; H, 6.32. Found: C, 65.16;
H, 6.37. IR (CH2Cl2 solution): ν(MC-O): 1997 cm-1
IR
(Nujol mull): 1994 (s), 1708 (s), 1062 (s), 1034 (s), 771 (vw),
764 (w), 722 (vw), 699 (w) cm-1 1H NMR (270 MHz, CDCl3/
a nitrogen atmosphere. Anal.
.
(η5-1-Meth yl-1-(2,3,4,5-tetr a m eth ylcyclop en ta d ien yl)-
p r op a n e)ir on Dica r bon yl Iod id e (7). 7 was prepared by
the method used for 6 in 73% yield and isolated as a black
brown solid. Anal. Calcd for C15H21O2FeI: C, 43.3; H, 5.05.
Found: C, 43.373; H, 5.074. IR (CH2Cl2 solution): ν(MC-O)
.
TMS (resolution poor)): δ 7.41-7.26 (10H, phenyl rings); 6.44
(broad doublet, J ) 10.11 Hz, 2H, H(2), H(3)); 3.04 (broad
doublet, J ) 10.6 Hz, 2H, H(1), H(4)); 2.07-1 (broad group of
peaks, 15H, vinyl methyls, C(8)-H and C(8)-CH2); 0.9 (mul-
tiplet, 3H, C(8)-CH3); 0.8 (multiplet, 3H, C(8)-CH2CH3). 13C
NMR (67.8 MHz, CDCl3/TMS): δ 222.56 (CtO); 137.4-126
(phenyl rings); 102.98/99.2/98.5/94.75/94.37 (C(3-7)); 83.87
(C(3A,4A)); 79.1/78.9 (C(2A,5A); 32.05 (C(8)); 28.76 (C(14));
18.13 (C(13)); 12.5 (C(15)); 9.34, 8.83 (C(9-12)).
R ea ct ion of [(η5-C5(CH 3)4C(H )(CH 3)(C2H 5))F e(CO)-
(m eth ylh exa -2,4-d ien oa te)]+[BF 4]- w ith Sod iu m Meth -
oxid e. A 0.10 g amount of sodium metal was dissolved in 20
cm3 of dry, degassed methanol under nitrogen, the solution
was cooled to 0 °C, and 0.1g of 10 was added. The solution
was stirred for 5 min before addition of 20 cm3 of distilled
water at 0 °C. The reaction mixture was extracted into diethyl
ether (80 cm3), dried over Na2SO4, filtered, and evaporated to
a red oil. The product 12 ((η5-1-methyl-1-(2,3,4,5-tetrameth-
2020, 1978 cm-1 1H NMR (270 MHz, CDCl3/TMS): δ 2.29 (w
.
multiplet, 1H, C(8)-H); 2.02 (s, 3H, vinyl Me); 1.99 (s, 3H,
vinyl Me); 1.96 (s, 3H, vinyl Me); 1.944 (s, 3H, vinyl Me); 1.57
(multiplet, 2H, C(8)-CH2CH3); 1.294 (doublet, J ) 7.15 Hz,
3H, C(8)-CH3); 0.932 (triplet, J ) 7.32 Hz, 3H, C(8)-CH2CH3).
13C NMR (67.8 MHz, CS2/TMS) δ 215.2 (CtO); 100.03/97.56/
97.12/96.3/94.28 (C(3-7)); 32.14 (C(8)); 30.18 (C(14)); 20.63
(C(13)); 12.91 (C(15)); 11.33/11.07/10.57/10.19 (C(9-12)).
(η5-(1S)-1-(6-m e t h oxyn a p h t h a le n yl)-1-(2,3,4,5-t e t r a -
m eth ylcyclop en ta d ien yl)eth a n e)F e(CO)2Sn Cl3 (8). A 1.0
g (1.84 mmol) amount of the iodide 6 and 0.687 g (3.68 mmol)
of anhydrous stannous chloride were refluxed in 20 cm3 of dry
methanol under nitrogen for 4 days until complete reaction
had occurred. The reaction mixture was cooled to room
temperature and then extracted into dichloromethane. The

Novel Chiral Cyclopentadienes
Organometallics, Vol. 16, No. 12, 1997 2645
ylcyclopentadienyl)propane)Fe(CO)(η3-C8H13O3)) was then sub-
(OCH3); 41.37/41.24 (C(5A)); 32.4/32.3 (C(8)); 30.1/29.8 (C(14));
22.1/22.07/20.54/19.81 (CH3 bonded to C(5A) and C(13)); 13.2/
12.77 (C(15)); 10.78/10.57/10.2/9.97/8.99/8.94/8.74/8.42 (C(9-
12)).
limed onto a cold finger to give 0.08 g as a red viscous oil. IR
(CH2Cl2 solution): ν(MC-O) 1931 cm-1 1H NMR (270 MHz,
.
CDCl3/TMS): δ 4.6 (dd, 1H, J (H(1)-H(2)) ) 10 Hz, J (H(2)-
H(3)) ) 8.2 Hz, H(2)); 3.67 (s, 3H, OCH3); 3.14 (s, 3H, OCH3);
2.70 (dd, 1H, J (H(3)-H(4)) ) 10 Hz, J (H(2)-H(3)) ) 8.2 Hz,
H(3)); 2.37/2.60 (pair of multiplets, 1H, C(8)-H); 1.91 (pair,
3H, vinyl methyls); 1.61 (pair, 3H, vinyl methyls); 1.59
(doublet, 1H, J (H(1)-H(2)) ≈ 10 Hz, H(1)); 1.53 (pair, 3H, vinyl
methyls); 1.45 (s, 3H, vinyl methyls); 1.26/1.42 (pair of
doublets, 3H, J ) 7.15 Hz, C(8)-CH3); 1.29 (doublet, 3H,
J (CH3-H(4)) ) 6.05 Hz, CH3 bonded to C(5A); 0.95 (pair of
1:2:1 triplets, 3H, J ) 7.32 Hz, C(8)-CH2CH3). 13C NMR (67.8
MHz, CDCl3/TMS): δ 224.11/224.08 (CtO); 175.7 (CdO); 100/
92.1/91.8/91.3/91.1/89.9 (C(3-7)); 83.6/83.5 (C(3A)); 79.28/79.25
(C(2A)); 64.08/63.97 (C(4A)); 55.76 (OCH3 at C(5A)); 50.9
Ack n ow led gm en t. We thank Roche Ireland Ltd. for
a gift of naproxen and the Irish Government (Forbairt)
for a grant (A.G.R.).
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and structure refinement details, positional and
thermal parameters, and bond distances and angles for 8 and
11 (15 pages). Ordering information is given on any current
masthead page.
OM950958G