General route to dissymmetric heteroannular-functionalized ferrocenyl 1,2-diphosphines: Selective synthesis and characterization of a new class of tri- and tetrasubstituted ferrocenyl compounds

Article abstract of DOI:10.1021/om050882g

Several monosubstituted-cyclopentadienyl anions (A-Li) and [1,2-bis(diphenylphosphino)-4-tert-butylcyclopentadienyl]lithium (B-Li) react with FeCl₂ to afford a novel class of multidentate ferrocenylphosphines (A-Fe-B). The proposed synthetic method represents a unique means to produce achiral dissymmetric 1,1′,2-substituted ferrocenes (A-Fe-B) bearing a heteroannular 1′-substituent which is different from the homoannular 1- and 2-substituents. The selectivity for the two-step reaction favors formation of the desired dissymmetric product (A-Fe-B) rather than the concurrent formation of the symmetric di- and tetrasubstituted ferrocenes (A-Fe-A and B-Fe-B). Therefore, this method allows access to a great number of dissymmetric multidentate metalloligands, especially when one considers that functionalized-Cp salts continue to expand in terms of number and diversity. Herein, emphasis was placed upon the ¹H, ¹³C, and ³¹P NMR characterization of the metalloligands; several examples exhibit intriguing conformational properties and rare through-space phosphorus nuclear-spin couplings.

Full text of DOI:10.1021/om050882g

Organometallics 2006, 25, 989-995
989
General Route to Dissymmetric Heteroannular-Functionalized
Ferrocenyl 1,2-Diphosphines: Selective Synthesis and
Characterization of a New Class of Tri- and Tetrasubstituted
Ferrocenyl Compounds
V. V. Ivanov, J.-C. Hierso,* R. Amardeil, and P. Meunier
Laboratoire de Synthe`se et Electrosynthe`se Organome´talliques associe´ au CNRS (UMR 5188), Faculte´ des
sciences Mirande, UniVersite´ de Bourgogne, 9 aVenue Alain SaVary, 21078 Dijon, France
ReceiVed October 14, 2005
Several monosubstituted-cyclopentadienyl anions (A-Li) and [1,2-bis(diphenylphosphino)-4-tert-
butylcyclopentadienyl]lithium (B-Li) react with FeCl2 to afford a novel class of multidentate ferro-
cenylphosphines (A-Fe-B). The proposed synthetic method represents a unique means to produce achiral
dissymmetric 1,1′,2-substituted ferrocenes (A-Fe-B) bearing a heteroannular 1′-substituent which is different
from the homoannular 1- and 2-substituents. The selectivity for the two-step reaction favors formation
of the desired dissymmetric product (A-Fe-B) rather than the concurrent formation of the symmetric di-
and tetrasubstituted ferrocenes (A-Fe-A and B-Fe-B). Therefore, this method allows access to a great
number of dissymmetric multidentate metalloligands, especially when one considers that functionalized-
Cp salts continue to expand in terms of number and diversity. Herein, emphasis was placed upon the 1H,
13C, and 31P NMR characterization of the metalloligands; several examples exhibit intriguing conformational
properties and rare “through-space” phosphorus nuclear-spin couplings.
Chart 1. Polyphosphine Catalytic Auxiliaries 1-3 Built on a
Introduction
Ferrocenyl Backbone
The tertiary aryl- and alkylphosphines play a major role in
modern metal-catalyzed organic reactions. For instance, most
of the highly efficient catalytic procedures reported to date for
C-C cross-coupling reactions are carried out in the presence
of phosphine auxiliary ligands.1 In addition to the classical
mono- and bidentate phosphine ligands, we and others recently
disclosed the high effectiveness of some multidentate phosphines
(tri- or tetraphosphines) in the palladium-catalyzed synthesis
of fine chemicals.2-4 C-C coupling that results from reaction
of organo bromides or chlorides with various organometallic
reagents has excellent synthetic scope. The ferrocenylphosphines
depicted in Chart 1, 1,1′,2,2′-tetrakis(diphenylphosphino)-4,4′-
di-tert-butylferrocene (Fc(P)4tBu; 1), 1,2-bis(diphenylphosphino)-
allylic amination of allyl acetates; the highest turnover frequen-
cies (TOF, h-1) reported to date resulted from these studies.5,6
The intrinsic properties of these ligands, their stability toward
air and moisture, allows them to be used under normal laboratory
conditions (non-glovebox). Their stabilizing properties and their
robustness under catalytic conditions (at low concentration in
solution at temperatures >100 °C) prompted us to develop a
synthetic route toward a more diverse structural class of 1′-
substituted 1,2-ferrocenyldiphosphines. The present paper pro-
vides details of the results obtained when a variety of substituted-
cyclopentadienyl anions were reacted with [1,2-bis(diphenylphos-
phino)-4-tert-butylcyclopentadienyl]lithium (t-BuCp(PPh2)2Li)
and iron(II) salts. The characterization and notable features of
the new dissymmetric 1′-substituted 1,2-ferrocenyldiphosphines
are described thoroughly. The synthetic method is a unique
means to producing multidentate ferrocenylphosphines bearing
a heteroannular 1′-substituent different from the homoannular
1- and 2-substituents. Emphasis is placed upon the 1H, 13C, and
1′-(diisopropylphosphino)-4-tert-butylferrocene (Fc(P)2 Bu(PiPr);
t
2), and 1,1′-bis[bis(5-methyl-2-furyl)phosphino]ferrocene (Fc-
[P(FuMe)2]2; 3), have been successfully employed in coupling
reactions such as the Suzuki-Miyaura (arylation), Heck (alkenyl
arylation), Sonogashira-Hagihara (alkynyl arylation), and Tsuji-
Trost type (allylation substitution with amine nucleophiles)
reactions. Compound 1 has been used to stabilize palladium
catalytic systems for Heck and Suzuki reactions at 0.01-
0.0001% catalyst loadings.2 Compound 2 has allowed palladium-
catalyzed alkynylation at 0.1-0.0001% catalyst loading, in some
cases under copper-free conditions.3 Compound 3, in combina-
tion with [PdCl(allyl)]2, gives a base-free catalytic system for
* To whom correspondence should be addressed. E-mail:
jean-cyrille.hierso@u-bourgogne.fr. Tel: +33 3 80 39 61 06. Fax:
+33 3 80 39 36 82.
(1) Farina, V. AdV. Synth. Catal. 2004, 346, 1553.
(2) Hierso, J.-C.; Fihri, A.; Amardeil, R.; Meunier, P.; Doucet, H.;
Santelli, M.; Donnadieu, B. Organometallics 2003, 22, 4490.
(3) Hierso, J.-C.; Fihri, A.; Amardeil, R.; Meunier, P.; Doucet, H.;
Santelli, M.; Ivanov V. V. Org. Lett. 2004, 6, 3473.
(4) Feuerstein, M.; Laurenti, D.; Bougeant, C.; Doucet, H.; Santelli, M.
Chem. Commun. 2001, 4, 325.
(5) Fihri, A.; Hierso, J.-C.; Vion, A.; Nguyen, D.-H.; Urrutigo¨ıty, M.;
Kalck, P.; Amardeil, R.; Meunier, P. AdV. Synth. Catal. 2005, 347, 1198.
(6) Hierso, J.-C.; Fihri, A.; Amardeil, R.; Meunier, P.; Doucet, H.;
Santelli, M. Tetrahedron 2005, 61, 9759.
10.1021/om050882g CCC: $33.50 © 2006 American Chemical Society
Publication on Web 01/12/2006

990 Organometallics, Vol. 25, No. 4, 2006
IVanoV et al.
31P NMR characterization of the formed metalloligands; several
compounds exhibit intriguing phosphorus nuclear-spin coupling
properties. A portion of this work has previously been published
in communication form.7
Scheme 1. Strategies for the Synthesis of Trisubstituted
Ferrocenesa
Results and Discussion
Synthetic Strategy. An examination of the literature reveals
that only a few ferrocenylpolyphosphine ligands of higher rank
than diphosphines are available for use in synthetic chemistry
and homogeneous catalysis.8,9 Precise descriptions for the
preparation and characterization of ferrocenyltriphosphines are
scarce. Additionally, while there have been numerous develop-
ments in the synthetic methodology of 1,2-substituted ferrocene
derivatives,10 the preparation of heteroannular 1,2,1′-trisubsti-
tuted ferrocenes, to our knowledge, is understudied. The elegant
works by the groups of Balavoine et al. and Hou et al. for the
synthesis of chiral polysubstituted ferrocenes11,12 and by Butler
et al. for the preparation of achiral or racemic analogues13
represent recent important contributions in this area.14,15
The selectivity problems encountered when using the direct
phosphorylation of the ferrocene backbone, in part, explains the
limited development of ferrocenylpolyphosphine ligands. For
example, the treatment of (diphenylphosphino)ferrocene with
n-BuLi and ClPPh2 typically yields four products at least:
unreacted (diphenylphosphino)ferrocene (22%), 1,1′-bis(diphen-
ylphosphino)ferrocene (dppf, 15%), 1,3,1′-tris(diphenylphos-
phino)ferrocene (51%), and 1,2,1′-tris(diphenylphosphino)-
ferrocene (6%).16 On the other hand, a number of efficient
methods are available for the selective formation of 1,2-
substituted ferrocenes via ortho-directing groups (chiral or
nonchiral), such assnonexhaustivelysamine,17 acetal,18 oxazo-
line,19 amide,20 sulfoxide,21 and phosphine oxide22 groups. With
these ferrocene derivatives as starting materials, a third substitu-
a DG ) directing group.
tion is possible (Scheme 1a). Some disadvantages are apparent,
however, as noted previously by Togni and co-workers.23 For
example, in the subsequent reaction it appears difficult to
selectively substitute the second Cp ring, since the “still active”
ortho-directing effect leads to the formation of 1,2,3-trisubsti-
tuted ferrocenes.
Another strategy to obtain 1,1′,2-substituted ferrocenes is
starting from 1-substituted ferrocenes with a directing group
(DG), which allows the introduction of two groups in a one-
pot procedure: the consequence is that the 1′,2-substitution leads
to the formation of two equal heteroannular groups (R1 in
Scheme 1b).23 The Butler method, based on the use of 1,1′-
dibromoferrocene and its novel ortho-directed metalation ef-
fect,13 does not increase “flexibility” in this particular problem,
since the 1- and 1′-substituents remain equal (Scheme 1c). Some
differently trisubstituted ferrocenes, called 1,1′-P,N-2-ferrocene
ligands by the authors, were synthesized by Hou et al. starting
from 1′-Br ferrocenyloxazoline (Scheme 1d);12 a minor incon-
venience of this method is that the 1′-Br ferrocenyloxazoline
derivative results from a five-step reaction sequence starting
with ferrocene (overall yield <20%).12c Finally, it is worth
noting the methodology developed by Manoury and co-workers
(Scheme 1e), using a 2-substituted ferrocenecarboxaldehyde,
where an aminoalkoxide is formed as a temporary protecting
group of the aldehyde function and as a temporary directing
group for the 1′-ortho lithiation.11 Nevertheless, to our knowl-
edge, these last two synthetic strategies have not been applied
to afford ferrocenyltriphosphines, which are our primary targets.
Stimulated by preliminary results in our group,24 we chose
to develop the strategy previously employed to obtain ferrocenyl
1,1′- and 1,2-diphosphines, as well as 1,1′,2,2′-tetraphosphines.
(7) Hierso, J.-C.; Ivanov V. V.; Amardeil, R.; Richard, P.; Meunier, P.
Chem. Lett. 2004, 33, 1296.
(8) For a recent review see: Atkinson, R. C. J.; Gibson, V. C.; Long, N.
J. Chem. Soc. ReV. 2004, 33, 313.
(9) For a review see: Hierso, J.-C.; Amardeil, R.; Bentabet, E.; Broussier,
R.; Gautheron, B.; Meunier, P.; Kalck, P. Coord. Chem. ReV. 2003, 236,
143.
(10) See for leading references: (a) Hayashi, T. In Ferrocenes: Homo-
geneous Catalysis, Organic Synthesis, Materials Science; Togni, A.,
Hayashi, T., Eds.; VCH: Weinheim, Germany, 1995; pp 105-142. (b)
Togni, A. In Ferrocenes: Homogeneous Catalysis, Organic Synthesis,
Materials Science; Togni, A., Hayashi, T., Eds.; VCH: Weinheim, Germany,
1995; pp 685-721. (c) Togni, A. Angew. Chem., Int. Ed. Engl. 1996, 35,
1475. (d) Kagan, H. B.; Riant, O. AdV. Asym. Synth. 1997, 2, 189. (e)
Richards, C. J.; Locke, A. J. Tetrahedron: Asymmetry 1998, 9, 2377. See
also ref 8 and references therein.
(11) (a) Iftime, G.; Daran, J.-C.; Manoury, E.; Balavoine, G. G. A.
Organometallics 1996, 15, 4808. (b) Balavoine, G. G. A.; Daran, J.-C.;
Iftime, G.; Manoury, E. J. Organomet. Chem. 1998, 567, 191.
(12) (a) Deng, W.-P.; Hou, X.-L.; Dai, L.-X.; Yu, Y.-H.; Xia, W. Chem.
Commun. 2000, 285. (b) Deng, W.-P.; You, S.-L.; Hou, X.-L.; Dai, L.-X.;
Yu, Y.-H.; Xia, W.; Sun, J. J. Am. Chem. Soc. 2001, 123, 6508. (c) Chesney,
A.; Bryce, M. R.; Chubb, R. W. J.; Batsanov, A. S.; Howard, J. A. K.
Synthesis 1998, 413.
(13) Butler, I. R.; Mu¨ssig, S.; Plath, M. Inorg. Chem. Commun. 1999,
2, 424.
(14) A patented work describes the access in three steps from (R)-N,N-
dimethyl-1-ferrocenylethylamine to 1,1′,2-trisubstituted chiral ferrocenyl
diphosphines bearing different phosphorus groups on the 1- and 1′-positions;
see: Pugin, B.; Landert, H.; Pioda, G. Patent WO 9815565 A1, 1998.
(15) The pioneering works by Hayashi et al. promoted 1,1′,2-trisubstituted
ferrocenes; see, for instance: Hayashi, T.; Kanehira, K.; Hagihara, T.;
Kumada, M. J. Org. Chem. 1988, 53, 113 and references therein.
(16) Butler, I. R.; Hobson, L. J.; Macan, S. M. E.; Williams, D. J.
Polyhedron 1993, 12, 1901.
(19) Sammakia, T.; Latham, H. A.; Schaad, D. R. J. Org. Chem. 1995,
60, 10.
(20) Tsukazaki, M.; Tinkl, M.; Roglans, A.; Chapell, B. J.; Taylor, N.
J.; Snieckus, V. J. Am. Chem. Soc. 1996, 118, 685.
(21) Hua, D. H.; Lagneau, N. M.; Chen, Y.; Robben, P. M.; Clapham,
G.; Robinson, P. D. J. Org. Chem. 1996, 61, 4508.
(22) Nettekoven, U.; Widhalm, M.; Kamer, P. C. J.; van Leeuwen, P.
W. N. M.; Mereiter, K.; Lutz, M.; Spek, A. L. Organometallics 2000, 19,
2299.
(17) Hayashi, T.; Yamamoto, K.; Kumada, M. Tetrahedron Lett. 1974,
4405.
(18) Riant, O.; Samuel, O.; Kagan, H. B. J. Am. Chem. Soc. 1993, 115,
5.
(23) Abbenhuis, H. C. L.; Burckhardt, U.; Gramlich, V.; Togni, A.;
Albinati, A.; Mu¨ller, B. Organometallics 1994, 13, 4481.

Ferrocenyl 1,2-Diphosphines
Organometallics, Vol. 25, No. 4, 2006 991
Scheme 2. Diphosphine Synthesis from Functionalized Cp
Salts with (a) Identical and (b) Different Cp Rings
In addition to the various ferrocenyltriphosphines obtained
from the new synthons [(diisopropylphosphino)cyclopentadienyl]-
lithium (CpLi-2) and [(bis(5-methyl-2-furyl)phosphino)cyclo-
pentadienyl]lithium (CpLi-6) and from the known [(diphen-
ylphosphino)cyclopentadienyl]lithium (CpLi-5),26 we examined
the results obtained from other functionalized-Cp salts with a
view to increasing the synthetic potentiality of the method.
Syntheses and Characterization of the Triphosphines.
From the phosphorylation and lithiation of CpLi, using first ClP-
(i-Pr)2 and then n-BuLi, CpLi-2 was isolated in 94% yield. The
metalloligand 1,2-bis(diphenylphosphino)-1′-(diisopropylphos-
t
phino)-4-tert-butylferrocene (Fc(P)2 Bu(PiPr); 2) was then ob-
tained in 60-70% yield (1.54 g) from the successive reaction
of t-BuCp(PPh2)2Li and CpLi-2 with FeCl2. The X-ray diffrac-
1
tion structure and the H, 13C, and 31P NMR spectroscopic
studies in solution have been previously reported for 2.3,7 The
NMR phosphorus signals detected at -0.93 ppm for P(i-Pr)2
and -22.01 ppm for PPh2 groups provide evidence for the
electronic difference between the phosphorus atoms. The most
remarkable feature of the compound is derived from the 13C
NMR spectroscopic data, for which a clear spin-spin nuclear
coupling constant (JCP ) 5.5 Hz) between the three carbon atoms
of the t-Bu group and the phosphorus atom bearing the isopropyl
groups is detected (unambiguously demonstrated by selective
phosphorus-decoupling NMR experiments; see Figure 1). As
these atoms are not held by the same Cp ring, the “shortest”
distance between the nucleus of interest is a five-bond distance
From the initial preparation of the adequately substituted
cyclopentadienes and their transformation into the corresponding
Cp alkali-metal salts, a variety of metallocenes are accessible
through subsequent reaction with a convenient transition-metal
chloride (see, for example, Scheme 2). This strategy is based
on the well-known preparation of ferrocenes from fulvenes,25
which can even be applied to form enantiopure ferrocenes from
optically active Cp synthons.23
To produce heteroannular 1′-functionalized ferrocenyl 1,2-
diphosphines by assembling the Cp rings, the dissymmetry can
be introduced via a two-step reaction (Scheme 2b). The first
dissymmetric ferrocene (4) built on the [1,2-bis(diphenylphos-
phino)-4-tert-butylcyclopentadienyl]lithium synthon has been
obtained in good yield (68%).24c This result was a priori
surprising, since the preparation of ferrocene derivatives from
two different Cp salts is generally regarded as leading to a quasi-
statistic mixture containing all three possible combinations: two
symmetric compounds and the dissymmetric species. We
postulated that the two-step methodology used minimizes the
quantities of symmetric species by stabilizing mono-Cp com-
plexes of iron (see Scheme 2b).7 Scheme 3 summarizes the
various species (2 and 5-9) we attempted to form using this
methodology from the corresponding Cp anions (CpLi-2, -5,
-6, -8, and -9 and CpNa-7) and [1,2-bis(diphenylphosphino)-
4-tert-butylcyclopentadienyl]lithium.
5
(C-C-C-Fe-C-P) that should not lead to a detectable JCP
4
spin-spin coupling interaction. Consistently, no other JCP or
5JCP coupling constants were observed. The conformation in
solution can be compared to that observed in the solid state
from single-crystal diffraction studies, since the molecular
structure reveals the proximity in space of the coupled atoms
(as pictured in Scheme 3). A short “through-space” distance of
d(P‚‚‚C) ) 3.64 Å is favored by the staggered conformation
(the Cp rings are staggered, with a twist angle calculated from
the mean value of the dihedral angles Ci-CNT(1)-CNT(2)-
Ci* ) 30.4°). Thus, the lone pair of the phosphorus P(i-Pr)2 is
clearly pointing toward the carbon atoms of the t-Bu group and
is most probably responsible for the transmission of the nuclear
spin information. This type of nonbonded interaction, which
Scheme 3. Heteroannular 1′-Functionalized Ferrocenyl 1,2-diphosphines

992 Organometallics, Vol. 25, No. 4, 2006
IVanoV et al.
Chart 2. Molecular Conformation of Highest Symmetry for
5 (Cs)a
a A conformation close to this one would explain a “through-space”
31P spin-spin coupling.
yield is lowered, partially due to the formation of about 10 mol
% of dppf and ca. 3 mol % of the symmetric tetrakis-
(diphenylphosphine)ferrocene compound. Surprisingly, the 31P-
{1H} NMR spectrum of 5 in CDCl3 shows a triplet at -19.3
ppm and a doublet at -23.0 ppm, respectively assigned to the
1′-PPh2 and 1,2-PPh2 groups. The observed spin-spin coupling
constant was found to be greater in C6D6 (JPP ) 5.0 Hz, a rather
4
high value for a presumed through-bond JPP) than in CDCl3
(JPP ) 2.8 Hz). Hence, it should be attributed to the “through-
space” spin coupling which is affected by Fc ring rotation and
by the changes in the relative orientation of the phosphine
groups, above all of the phosphorus lone pairs.28 To facilitate
via-space spin interaction of the phosphorus nucleus, the relative
rotation of the Cp rings has to occur rapidly, though it is
restricted to a certain degree through the conformation of higher
symmetry (Cs) represented in Chart 2.
The 1H NMR spectrum of 5 in CDCl3 displays three
multiplets from Cp H atoms (2H each) at 4.07, 4.17, and 4.20
ppm, assigned correspondingly to 3,5-, 2′,5′-, and 3′,4′-H. It is
noteworthy that for the related compound 1,1′,2-tris(diphen-
ylphosphino)ferrocene reported by Butler et al.16 two singlet
resonances are observed at -18.4 and -25.4 ppm in CDCl3.
The absence of multiplicity indicates that no phosphorus spin-
spin coupling is observed. This highlights the crucial role of
the t-Bu group in the conformation of 5 in solution.
The phosphorylation and lithiation of CpLi, using BrP(FuMe
)
2
and n-BuLi, give CpLi-6 in excellent yield (90%). Following
the methodology described above, the metalloligand Fc(P)2-
tBu(PFuMe) (6) was obtained, as orange needles, in a disap-
pointingly poor yield (3%, 160 mg) after workup procedures.
In the various reactions conducted, the symmetric ferrocene
species were obtained, together with a considerable amount of
insoluble red solid material; clearly further optimization studies
are required for the efficient synthesis of 6. The 31P NMR
spectrum of 6 in CDCl3 exhibits two singlets at -22.7 (1,2-
PPh2) and -64.9 ppm (1′-PFuMe), confirming the expected
electronic difference between the phosphorus nuclei. As ob-
Figure 1. 13C NMR spectra for 2 with selective phosphorus spin
decoupling at t-Bu carbon chemical shifts: (1) δ 31.7 (s, 1C,
t-BuCCH3), 32.4 (d, 3C, through-space JCP ) 5.5 Hz, t-BuCCH3),
no phosphorus decoupling; (2) same spectrum as (1), with P(i-Pr)2
decoupling (at -0.9 ppm); (3) same spectrum as (1), with PPh2
decoupling (at -22 ppm); (4) same spectrum as (1), with broad-
band decoupling (bb).
requires steric crowding, is very rare and was first experimen-
tally detected in JFF couplings27 and recently for JPP couplings
in ferrocenylpolyphosphine metalloligands and their coordina-
tion complexes.28
1
served in the case of 5, the H NMR spectrum of 6 in CDCl3
displays three multiplets from the Cp H atoms (2H each)
centered at 4.13, 4.10, and 4.18 ppm, respectively, assigned to
3,5-, 2′,5′-, or/and 3′,4′-H. The methyl substituents contained
within the furyl groups are observed at 2.28 ppm. The furyl
protons appear at 5.90 and 6.38 ppm.29
From the successive reaction of t-BuCp(PPh2)2Li and CpLi-5
with FeCl2, 1,1′,2-tris(diphenylphosphino)-4-tert-butylferrocene
t
(Fc(P)2 Bu(P); 5) was obtained in high yield (2.60 g, 84%). The
Other Functionalizations. With the view to evaluating access
to other dissymmetric heteroannular-substituted ferrocenyl 1,2-
diphosphines using the above strategy, various syntheses were
carried out from known functionalized Cp synthons. We first
obtained the new tetraphosphine 1,1′,2,3′-tetrakis(diphenylphos-
(24) (a) Ninoreille, S.; Broussier, R.; Martel, R.; Kubicki, M. M.;
Gautheron, B. Bull. Soc. Chim. Fr. 1995, 132, 128. (b) Broussier, R.;
Ninoreille, S.; Bourdon, C.; Blacque, O.; Ninoreille, C.; Kubicki, M. M.;
Gautheron, B. J. Organomet. Chem. 1998, 561, 85. (c) Broussier, R.;
Bentabet, E.; Mellet, P.; Blacque, O.; Boyer, P.; Kubicki, M. M.; Gautheron,
B. J. Organomet. Chem. 2000, 598, 365.
(25) (a) Knox, G. R.; Pauson, P. L. Proc. Chem. Soc. 1958, 289. (b)
Knox, G. R.; Munro, J. D.; Pauson, P. L.; Smith, G. H.; Watts, W. E. J.
Chem. Soc. 1961, 4619.
(26) Casey, C. P.; Bullock, R. M.; Fultz, W. C.; Rheingold, A. L.
Organometallics 1982, 1591.
(27) For a recent review see: Contreras, R. H.; Barone, V.; Facelli, J.
C.; Peralta, J. E. Annu. Rep. NMR Spectrosc. 2003, 51, 167.
(28) Hierso, J.-C.; Fihri, A.; Ivanov, V. V.; Hanquet, B.; Pirio, N.;
Donnadieu, B.; Rebie`re, B.; Amardeil, R.; Meunier, P. J. Am. Chem. Soc.
2004, 126, 11077.
t
phino)-4-tert-butylferrocene (Fc(P)2 Bu(PP′); 9). This kind of
1,2- plus 1′,3′-substitution is rare and extremely difficult to
obtain in a controlled manner by starting from ferrocenes,
whatever the method employed, since most of the approaches
are based on ortho-directed substitutions.30 The addition of [1,3-
bis(diphenylphosphino)cyclopentadienyl]lithium (CpLi-9) to the
(29) The corresponding NMR spectrum is available as Supporting
Information.

Ferrocenyl 1,2-Diphosphines
Organometallics, Vol. 25, No. 4, 2006 993
tBu(CHO); 7) is obtained in pure form as brick red spangles
after recrystallization from heptane and then from ethanol. The
31P NMR spectrum of 7 exhibits a singlet at -24.4 ppm. The
1H NMR spectrum shows three multiplets for the Cp H atoms
(2H each) at 4.21 (3,5-H), 4.42 (2′,5′-H), and 4.64 (3′,4′-H).29
The peak corresponding to the formyl group is found at 8.47
ppm.
Chart 3. Symmetric Molecular Conformations S and T for 9
Following the method described by Brasse et al., the syn-
thon [(1-methyl-1-(diphenylphosphino)ethyl)cyclopentadienyl]-
lithium33 (CpLi-8) was prepared from HPPh2, n-BuLi, and 6,6-
dimethylfulvene. Without isolation, CpLi-8 was directly added
as a THF solution to a t-BuCp(PPh2)2Li/FeCl2 mixture to give
mixture of FeCl2 and t-BuCp(PPh2)2Li gave 9 in 45% yield (1.5
g) after workup procedures. Interestingly, the31P{1H} NMR
spectrum in CDCl3 shows two broad singlets (visibly doublets)29
at -19.6 and -23.9 ppm, suggesting the existence of JP P
<
A
B
t
the metalloligand Fc(P)2 Bu(Me2CP) (8). The pure product was
3 Hz between two groups of equivalent phosphorus atoms. The
31P NMR experiments conducted at low temperature (243 and
213 K) did not simplify the spectrum. Consequently, from the
two conformations of higher symmetry (displaying pairs (a PA
pair and a PB pair) of homoannular chemically equivalent
phosphorus) anticipated for 9 (S and T pictured in Chart 3), S
should be the conformation allowing facile phosphorus spin-
spin coupling “through-space”. It appears reasonable to assume
that, in solution, a rapid rotation of the Cp rings is restricted to
a certain degree around the conformation S, since an unrestricted
rotation probably would not facilitate the observation of through-
space JPP couplings between the heteroannular phosphorus
atoms.
obtained after column chromatography (SiO2, 4:1 v/v toluene-
hexane) and then recrystallized from hot methanol. The 31P
NMR spectrum of 8 exhibits two singlets at 29.4 and -24.0
ppm (CpPPh2),29 consistent with the reported data from the
literature concerning the chemical shift of the -(PPh2)C(Me)2
1
moiety (about 30 ppm).33,34 The H NMR spectrum shows a
doublet for the methyl groups centered at 0.81 ppm (3JPH
)
14.4 Hz) and three multiplets (2 H each) centered at 3.64, 3.82,
and 4.11 ppm for the Cp H atoms.29
Conclusion
The 1H NMR spectrum of 9 in CDCl3 displays three
multiplets from the Cp H atoms, two centered at 4.20 and 4.65
ppm (2H each) respectively assigned to 3,5- and 4′,5′-H, and
one at 3.64 ppm (1H) for 2-H. The Experimental Section details
A methodology for the preparation of dissymmetric achiral
trisubstituted ferrocenes from two different Cp salts has been
described; the process is efficient and is complete in two simple
steps. The yields of ferrocene derivatives vary from poor (3%)
to high (84%), depending on the functionalized Cp synthons.
To check the generality of the preparative method, the syntheses
have been carried out following similar conditions; clearly, some
reactions will require further optimization studies. Nevertheless,
in almost all cases, the selectivity was in favor of the formation
of the dissymmetric 1,1′,2-substituted ferrocene, against the
concurrent formation of the symmetric di- and tetrasubstituted
ferrocenes. Therefore, this method opens up the way to an
important eclectic array of multidentate metalloligands, par-
ticularly considering the ever-expanding availability of Cp
salts.35 The newly prepared ferrocenylphosphines display,
especially at the phosphorus atoms, very different electronic,
steric, and conformational properties. Further work will aim at
taking advantage of these structural properties in homogeneous
and heterogeneous catalysis, as well as in materials science.
a consistent attribution for the proposed structure, based on 13
C
J-modulation and 1H/13C, 1H/1H correlation spectroscopic studies
(HMBC, HMQC).
Preliminary experiments were conducted to prepare the
compounds 7 and 8, these two trisubstituted ferrocene deriva-
tives being potentially interesting. The diphosphine 7, bearing
a reactive aldehyde function at the “lower” Cp ring,23 might
provide access to 1′-substituted ferrocene derivatives, in addition
to the triphosphines, or could allow anchoring of the 1,2-bis-
(diphenylphosphino)-4-tert-butylferrocenyl moiety to a surface
or to a suitable polymer or dendritic core. In the case of 8, the
idea was to give to the resulting triphosphine a more flexible
arm through use of a methylene spacer and to observe the effect
induced on the stability of the ligand through the removal of a
phosphorus from the Cp aromaticity (flexibility and stability;31
these two concepts are important in relation to catalysis).
The dissymmetric ferrocene derivatives 7 and 8 were obtained
in satisfying quantities (700 mg and 1 g, respectively) but in
insufficient yields (20% and 15% of pure recrystallized mate-
rial). For both of these compounds, less than 1 mol % of the
symmetric ferrocene derivatives was detected in the crude
product by NMR spectroscopy; therefore, the decomposition
(or oligomerization) of the monosubstituted-Cp synthons, under
the standardized conditions employed, is possible. From the
successive reaction of t-BuCp(PPh2)2Li and a THF solution of
(formylcyclopentadienyl)sodium (CpNa-7)32 with FeCl2, 1,2-
bis(diphenylphosphino)-1′-formyl-4-tert-butylferrocene (Fc(P)2-
Experimental Section
The reactions were carried out in oven-dried (115 °C) glassware
under an argon atmosphere using Schlenk and vacuum-line
techniques. FeCl2 from a commercial source was used (Aldrich
anhydrous beads, 99.9%, H2O <100 ppm). The solvents were
distilled over appropriate drying and deoxygenating agents prior
to use. 1H (300.13 and 500.13 MHz), 31P (121.49 and 202.46 MHz),
and 13C NMR (75.47 and 125.77 MHz), including low-temperature,
13C J-modulation APT, COSY 1H-1H, HMQC, and HMBC NMR
experiments, were performed in our laboratory (on Bruker 300 and
DRX 500 instruments), in CDCl3 at 293 K unless otherwise stated.
Elemental analyses were performed by the analytical service of the
(30) The 1,3-bis(diphenylphosphino)ferrocene can be obtained from the
ortho dilithiation of one of the cyclopentadienyl rings of 1,1′-dibromofer-
rocene: Butler, I. R.; Drew, M. G. B.; Greenwell, C. H.; Lewis, E.; Plath,
M.; Mu¨ssig, S.; Szewczyk, J. Inorg. Chem. Commun. 1999, 2, 576.
(31) The ligand Tedicyp has four flexible -CH2PPh2 groups and is very
efficient in a large range of arylation and amination reactions; see ref 1
and: Laurenti, D.; Feurstein, M.; Pepe, G.; Doucet, H.; Santelli, M. J. Org.
Chem. 2001, 66, 1633.
(33) Brasse, C. C.; Englert, U.; Salzer, A.; Waffenschmidt, H.; Was-
serscheid, P. Organometallics 2000, 19, 3818.
(34) Bosch, B. E.; Erker, G.; Fro¨hlich, R.; Meyer, O. Organometallics
1997, 16, 5449.
(35) (a) Butenscho¨n, H. Chem. ReV. 2000, 100, 1527-1564. For other
Cp salts see: (b) Koch, T.; Hey-Hawkins, E. Polyhedron 1999, 18, 2113.
(c) Ho¨cher, T.; Blaurock, S.; Hey-Hawkins, E. Eur. J. Inorg. Chem. 2002,
1174 and references therein.
(32) Hafner, K.; Schulz, G.; Wagner, K. Justus Liebigs Ann. Chem. 1964,
678, 39.

994 Organometallics, Vol. 25, No. 4, 2006
IVanoV et al.
LSEO of the “Universite´ de Bourgogne” (Eager 200). Mass spectra
were recorded on a Kratos Concept IS instrument.
(s, p-Ph), 132.9 (t, 2JPC ≈ 10.3 Hz, o-Ph), 133.8 (d, JPC ) 21.0 Hz,
2
o-Ph), 135.1 (dt, JPC ≈ 10.9 Hz, JP′C ) 1.5 Hz, o-Ph), 137.6 (t,
2
2JPC ≈ 2.9 Hz, ipso-Ph), 138.8 (t, JPC ≈ 4.7 Hz, ipso-Ph), 139.5
Synthesis of Cyclopentadienyl Salts. The known cyclopenta-
dienyl salts t-BuCp(PPh2)2Li,2,24c CpLi-5,26 CpLi-8,33 CpLi-924c and
NaCp-732 were synthesized according to literature reports.
(d, JPC ) 14.8 Hz, ipso-Ph). 31P{1H} NMR: δ -22.7 (d, TSJ ) 2.8
Hz, 1,2-PPh2), -19.3 (t, TSJ ) 2.8 Hz, 1′-PPh2). 31P{1H} NMR
(C6D6): δ -21.9 (d, TSJ ) 5.0 Hz, 1,2-PPh2), -20.0 (t, TSJ ) 5.0
Hz, 1′-PPh2).
(a) [(Diisopropylphosphino)cyclopentadienyl]lithium (CpLi-
2). To a stirred suspension of CpLi (2.07 g, 28.7 mmol) in 25 mL
of toluene was added dropwise a solution of ClP(i-Pr)2 (3.95 g,
25.9 mmol) in 10 mL of toluene at -80 °C. The reaction mixture
was stirred for 2 h, with the temperature slowly raised up to 0 °C.
A 20 mL portion of hexane was then added to the mixture, and
after 10 min it was filtered over Celite. The filtrate was evaporated
almost to dryness, and 40 mL of hexane was added to the residue.
The resulting colorless solution was treated with n-BuLi (17 mL,
1.6 M in hexane, 27.2 mmol) at 0 °C. As no precipitate appeared,
the reaction mixture was evaporated to dryness and then triturated
with hexane (60 mL) to provide a air-sensitive white precipitate of
CpLi-2 that was filtered off, washed with hexane, and dried under
vacuum (4.59 g, 94% yield). 1H NMR (THF-d8): δ 0.92 (m, 12H,
CH3), 1.86 (m, 2H, CH(CH3)2), 5.83 (m, 2H, Cp H), 5.89 (m, 2H,
Cp H). 31P{1H} NMR (THF-d8): δ -3.7 ppm.
(b) [(Bis(5-methyl-2-furyl)phosphino)cyclopentadienyl]lithium
(CpLi-6). To a stirred suspension of CpLi (6.03 g, 83.7 mmol) in
120 mL of toluene was added dropwise a solution of bis(5-methyl-
2-furyl)bromophosphine (BrP(FuMe)2; 15.3 g, 79.7 mmol) in 40 mL
of toluene at -80 °C. The reaction mixture was stirred for 1 h,
with the temperature to slowly raised to 20 °C, and then was stirred
for 1 h at room temperature. The mixture was filtered over Celite.
The precipitate of LiBr was washed with toluene (10 mL). The
filtrate was evaporated almost to dryness, and 100 mL of hexane
was added to the residue. The resulting colorless solution was
treated with n-BuLi (50 mL, 1.6 M in hexane, 80 mmol) at 0 °C.
The reaction mixture was stirred for 10 min at 0 °C. The
air-sensitive white precipitate of CpLi-6 that formed was filtered,
washed with hexane, and dried under vacuum (13.08 g, 90% yield).
1H NMR (THF-d8): δ 2.25 (m, 6H, CH3), 5.89 (m, 4H, Cp), 6.18
(m, 2H, furyl), 6.27 (m, 2H, furyl). 31P{1H} NMR (THF-d8): δ
-63.9 ppm.
(b) 1,2-Bis(diphenylphosphino)-1′-[bis(5-methyl-2-furyl)phos-
phino]-4-tert-butylferrocene (6). To a stirred suspension of FeCl2
(0.88 g, 6.9 mmol) in 25 mL of THF was added dropwise at -40
°C a solution of t-BuCp(PPh2)2Li (3.64 g, 7.3 mmol) in 40 mL of
THF. After it was stirred for 2 h at room temperature, the reaction
mixture was treated at -40 °C with a 25 mL THF solution of
CpLi-6 (1.23 g, 6.7 mmol). The reaction mixture was then stirred
for 1 h at room temperature, and the solvent was evaporated under
vacuum. The residue was refluxed in 80 mL of toluene for 5 h.
The mixture was cooled and filtered under air over a paper filter.
A red solid material insoluble in toluene as well as in other organic
solvents and water was obtained in considerable quantity. The crude
product was subjected to column chromatography (SiO2, 5:1
toluene-hexane) to yield first 0.92 g of 1 (24 mol %), 0.26 g (14
mol %) of 1,1′-bis[bis(5-methyl-2-furyl)phosphino]ferrocene, and
finally 0.16 g of 6 (3% yield). Anal. Calcd for C48H45FeO2P3
1
(802.7): C, 71.83; H, 5.65. Found: C, 71.69; H, 5.59. H NMR:
δ 1.13 (s, 9H, t-Bu), 2.27 (s, 6H, CH3), 4.10 (dd, JHH ≈ JPH ) 1.8
Hz, 2H, 3′,4′-Fc (or 2′,5′-Fc)), 4.13 (m, 2H, 3,5-Fc), 4.18 (dd, JPH
) 3.3 Hz, 3JHH ) 1.8 Hz, 2H, 2′,5′-Fc (or 3′,4′-Fc)), 5.91 (m, 2H,
3-H furyl), 6.37 (m, 2H, 4-H furyl), 6.90-7.09 (m, 10H, Ph), 7.35
(m, 6H, m,p-Ph), 7.62 (m, 4H, o-Ph). 31P{1H} NMR: δ -64.9 (s,
P[FuMe]2), -22.7 (s, 1,2-PPh2).
(c) 1,2-Bis(diphenylphosphino)-1′-formyl-4-tert-butylferrocene
(7). To a stirred suspension of FeCl2 (0.67 g, 5.3 mmol) in 10 mL
of THF was added dropwise, at -40 °C, a solution of t-BuCp-
(PPh2)2Li (2.72 g, 5.5 mmol) in 25 mL of THF. After it was stirred
for 2 h at room temperature, the reaction mixture was treated at
-40 °C with a 10 mL THF solution of (formylcyclopentadienyl)-
sodium prepared without isolation from CpNa and HCO2Et32 (0.64
g, 5.5 mmol). The reaction mixture was stirred overnight at room
temperature and evaporated under vacuum, and the residue was
refluxed in 60 mL of cyclohexane for 30 min. The reaction mixture
was then cooled and filtered under air over a paper filter. The crude
product was submitted to recrystallization first from heptane and
then from ethanol to give 0.69 g (20% yield) of 7 as brick-red
spangles. Anal. Calcd for C39H36FeOP2 (638.5): C, 73.36; H, 5.68.
Found: C, 73.32; H, 5.66. MS (EI): m/z (%) 638 (100) [M]+, 623
(22) [M - CH3]+, 610 (33) [M - CO]+, 595 (18) [M - CO -
CH3]+. 1H NMR: δ 1.18 (s, 9H, t-Bu), 4.21 (m, 2H, 3,5-Fc), 4.42
(m, 2H, 2′,5′-Fc), 4.64 (m, 2H, 3′,4′-Fc), 6.9-7.1 (m, 10H, Ph),
7.38 (m, 6H, m,p-Ph), 7.64 (m, 4H, o-Ph). 13C{1H} NMR: 30.8
(s, C(CH3)3), 31.2 (s, C(CH3)3), 71.6, 71.8 (s, 1C each, Fc CH),
75.2 (m, 1C, Fc CH), 80.4 (s, 1′-Fc), 83.6 (dd, JPC ) 9.8 Hz, JP′C
) 8.8 Hz, 1,2-Fc), 127.7 (t, JPC ) 3.5 Hz, m-Ph), 127.9 (s, p-Ph),
128.4 (t, JPC ) 4.3 Hz, m-Ph), 129.5 (s, p-Ph), 132.7 (t, JPC ) 10.2
Hz, o-Ph), 135.0 (t, JPC ) 10.9 Hz, o-Ph), 136.9 (t, JPC ) 2.6 Hz,
ipso-Ph), 137.9 (t, JPC ) 4.5 Hz, ipso-Ph), 193.7 (s, CHO). 31P-
{1H} NMR: δ -24.4 (s).
Synthesis of Substituted Ferrocenes. The syntheses of com-
pounds 1-4 have been reported elsewhere.2,3,5-7,24c
(a) 1,1′,2-Tris(diphenylphosphino)-4-tert-butylferrocene (5).
To a stirred suspension of FeCl2 (0.53 g, 4.2 mmol) in 15 mL of
THF was added dropwise at -40 °C a solution of t-BuCp(PPh2)2-
Li (2.18 g, 4.4 mmol) in 25 mL of THF. After it was stirred for 2
h at room temperature, the reaction mixture was treated at -40 °C
with a THF solution (10 mL) of CpLi-5 (1.00 g, 3.9 mmol). The
solvent was then evaporated under vacuum, and the residue was
refluxed in 50 mL of toluene for 3 h. The reaction mixture was
cooled and filtered under air. The crude product was subjected to
column chromatography (SiO2, 4:1 toluene-hexane) to provide first
0.15 g (3 mol %) of 1, 0.10 g (10 mol %) of 1,1′-bis(diphenylphos-
phino)ferrocene, and 2.60 g of 5 (yield 84%). Anal. Calcd for
C50H45FeP3 (794.7): C, 75.57; H, 5.71. Found: C, 75.59; H, 5.68.
MS (EI): m/z (%) 794 (24) [M]+, 717 (<1) [M - Ph]+, 609 (2)
[M - PPh2]+, 554 (100) [M - PPh2 - C4H8]+, 477 (9) [M -
1
PPh2 - C4H8 - Ph]+. H NMR: δ 1.03 (s, 9H, t-Bu), 4.07 (dd,
3
3
(d) 1,2-Bis(diphenylphosphino)-1′-[1-methyl-1-(diphenylphos-
phino)ethyl]-4-tert-butylferrocene (8). According to the method
of Brasse et al.,33 to a stirred solution of Ph2PH (2 mL, 11.5 mmol)
in Et2O (20 mL) at -80 °C was added first n-BuLi (7.3 mL, 1.6 M
in hexane, 11.7 mmol) and then after 20 min a solution of 6,6-
dimethylfulvene (1.18 g, 11.1 mmol) in THF (10 mL) at -40 °C.
The reaction mixture was stirred for 1 h at room temperature and
the solution of CpLi-8 used for the following synthesis. To a stirred
suspension of FeCl2 (1.20 g, 9.5 mmol) in 30 mL of THF was
added dropwise at -40 °C a solution of t-BuCp(PPh2)2Li (5.00 g,
10.1 mmol) in 20 mL of THF. After it was stirred for 2 h at room
JPH ) 3.3 Hz, JHH ) 1.8 Hz, 2H, 2′,5′-Cp), 4.17 (dd, JHH ≈ JPH
) 1.8 Hz, 2H, 3′,4′-Cp), 4.20 (dd, 2 JPH ≈ 1.5 Hz, 2H, 3,5-Cp),
6.91-7.12 (m, 10H, Ph, 1,2-PPh2), 7.13-7.26 (m, 10H, Ph, 1′-
PPh2), 7.33 (m, 6H, m,p-Ph 1,2-PPh2), 7.64 (m, 4H, o-Ph 1,2-PPh2).
The JPH values observed could be either “through-bond” (homoan-
nular) or “through-space” (heteroannular) couplings. 13C{1H}
NMR: δ 30.5 (s, C(CH3)3), 31.3 (d, JPC ) 1.5 Hz, C(CH3)3), 71.4
(m, 3, 5-Fc), 72.0 (m, 3′,4′-Fc), 74.4 (d, JPC ) 11.0 Hz, 2′,5′-Fc),
80.2 (d, JPC ) 12.5 Hz, 1′-Fc), 81.9 (m, 1,2-Fc), 106.8 (s, 4-Fc),
127.4 (t, 2JPC ≈ 3.5 Hz, m-Ph), 127.5 (s, p-Ph), 128.0 (d, JPC ) 7.2
2
Hz, m-Ph), 128.1 (t, JPC ≈ 8.8 Hz, m-Ph), 128.3 (s, p-Ph), 128.8

Ferrocenyl 1,2-Diphosphines
Organometallics, Vol. 25, No. 4, 2006 995
Chart 4. Conformational View Consistent with NMR Data
and Phenyl Assignmentsa
of THF was added dropwise at -40 °C a solution of t-BuCp(PPh2)2-
Li (1.86 g, 3.7 mmol) in 20 mL of THF. After it was stirred for 2
h at room temperature, the reaction mixture was treated at -40 °C
with a 20 mL THF solution of CpLi-9 (1.60 g, 3.6 mmol). The
solvent was evaporated, and the residue was refluxed in 40 mL of
toluene for 3 h. The reaction mixture was cooled and filtered in air
over a paper filter. The crude product was subjected to column
chromatography (SiO2, 4:1 v/v hexane-dioxane) to yield 1.50 g
(45%) of 1,1′,2,3′-tetrakis(diphenylphosphino)-4-tert-butylferrocene
(9). Anal. Calcd for C62H54FeP4 (978.9): C, 76.00; H, 5.56.
Found: C, 76.06; H, 5.60. MS (EI): m/z (%) 978 (100) [M]+, 901
(10) [M - Ph]+, 794 (75) [M - PPh2]+. For compound 9, a
complete NMR attribution has been done with the help of 2D
correlation spectroscopy; the chemical shifts are attributed by the
a The phenyl types are A (exo), B (endo), and C.
1
numbering given in Chart 4. H NMR: δ 0.70 (s, 9H, t-Bu), 3.64
(m, 1H, 2′-Fc), 4.20 (m, 2H, 3,5-Fc), 4.65 (m, 2H, 4′,5′-Fc), 6.86-
7.06 (m, 10H, A-Ph), 7.10-7.32 (m, 26H, C-, D-Ph, m,p-B-Ph),
7.59 (m, 4H, o-B-Ph). 13C{1H} NMR: δ 30.5 (s, C(CH3)3), 31.8
(m, C(CH3)3), 73.7 (d, JPC ) 3.8 Hz, 3,5-Fc), 75.2 (s, 2′-Fc), 78.6
(m, 4′,5′-Fc), 82.0 (d, JPC ) 14.3 Hz, 1′,3′-Fc), 82.7 (dd (pseudo-
temperature, the reaction mixture was treated at -40 °C with the
above-prepared solution of CpLi-8. The reaction mixture was
evaporated under vacuum, and the residue was refluxed in 100 mL
of toluene for 20 h. The reaction mixture was cooled and filtered
under air over a paper filter. The crude product was subjected to
column chromatography (SiO2, 4:1 v/v toluene-hexane) to provide
1.0 g (15% yield) of the desired product 8 after recrystallization
from hot methanol. An important red fraction does not migrate on
the column. The product in solution is more air-sensitive than its
congeners; consequently, the chromatography fractions should be
rapidly handled. Anal. Calcd for C53H51FeP3 (836.8): C, 76.08; H,
6.14. Found: C, 76.05; H, 6.14. 1H NMR: δ 0.81 (d, 3JPH ) 14.4
Hz, 6H, CH3), 1.17 (s, 9H, t-Bu), 3.64 (m, 2H, 2′,5′-Fc (or 3′,4′-
Fc)), 3.82 (m, 2H, 3′,4′-Fc (or 2′,5′-Fc)), 4.11 (m, 2H, 3,5-Fc),
6.75-6.97 (m, 10H, Ph), 7.05-7.32 (m, 16H, Ph), 7.54 (m, 4H,
o-Ph). 13C{1H} NMR: 27.4 (d, 2JPC ) 18.6 Hz, C(CH3)2PPh2), 31.2
(s, C(CH3)3), 32.5 (s, C(CH3)3), 35.2 (d, 1JPC ) 19.8 Hz, C(CH3)2-
PPh2), 68.8 (m, 3′,4′-Fc (or 2′,5′-Fc)), 69.8 (d, 3JPC ) 4.5 Hz, 2′,5′-
2
t), JPC ≈ 8.3 Hz, 1,2-Fc), 108.6 (s, 4-Fc), 127.9 (dd (pseudo-t),
2JPC ≈ 4.5 Hz, m-A-Ph), 128.0 (s, p-Ph), 128.3-128.5 (m, Ph),
128.8 (ddd (p-sext), 2JPC ) 4.5 Hz, JP′C ≈ 0.8 Hz, m-B-Ph), 129.4
(s, p-Ph), 133.0 (d, JPC ) 19.6 Hz, o-C-Ph (or o-D-Ph)), 133.5 (dd
(pseudo-t), 2JPC ≈ 10.6 Hz, o-A-Ph), 135.6 (d, JPC ) 23.4 Hz, o-D-
2
Ph (or o-C-Ph)), 136.0 (ddd (p-sext), JPC ≈ 10.6 Hz, JP′C ) 2.3
Hz, o-B-Ph), 137.6 (m, ipso-B-Ph (or ipso-A-Ph)), 138.7 (d, JPC
)
14.3 Hz, ipso-C-Ph (or ipso-D-Ph)), 139.3 (m, ipso-A-Ph (or ipso-
B-Ph)), 141.8 (d, JPC ) 15.9 Hz, ipso-D-Ph (or ipso-C-Ph)). 31P-
TS
{1H} NMR: δ -19.6 (d,
J
≈ 2.2 Hz, 1′,3′-PPh2), -23.9 (d,
PP
TS
J
≈ 2.2 Hz, 1,2-PPh2).
PP
Acknowledgment. We sincerely acknowledge financial
support from the “Conseil Re´gional de Bourgogne”. Thanks are
also due to Y. Coppel (from LCC-CNRS Toulouse), to I. J. S.
Fairlamb (from York University), to G. Delmas and S. Royer
for technical assistance, and to Ph. Richard for fruitful discus-
sions.
2
Fc (or 3′,4′-Fc)), 71.0 (s, 3,5-Fc), 80.7 (m, 1,2-Fc), 102.2 (d, JPC
) 6.0 Hz, 1′-Fc), 107.3 (s, 4-Fc), 127.9 (s, p-Ph), 127.9 (t, m-Ph),
3
128.0 (d, JPC ) 7.2 Hz, m-Ph), 128.7 (t, JPC ) 4.4 Hz, m-Ph),
129.1 (s, p-Ph), 129.5 (s, p-Ph), 133.1 (t, JPC ) 10.3 Hz, o-Ph),
135.4 (d, JPC ) 20.4 Hz, o-Ph), 135.9 (t, JPC ) 11.6 Hz, o-Ph),
136.3 (d, JPC ) 20.3 Hz, ipso-Ph), 138.0 (m, ipso-Ph), 139.5 (m,
ipso-Ph). 31P{1H} NMR: δ 29.4 (s, CMe2PPh2), -24.0 (s, 1,2-
PPh2).
1
Supporting Information Available: Figures giving H NMR
spectra of 6-8 and 31P NMR spectra of 8 and 9. This material is
available free of charge via the Internet at http://pubs.acs.org.
(e) 1,1′,2,3′-Tetrakis(diphenylphosphino)-4-tert-butylferrocene
(9). To a stirred suspension of FeCl2 (0.46 g, 3.7 mmol) in 12 mL
OM050882G