New lithium phosphonium diylides: A methylene and a cyclopentadienyl moiety as ylidic coordination sites

Article abstract of DOI:10.1021/om201182y

A set of lithium phosphonium diylides Li[CH₂-PR ₂-Cp^X] (9-12; Cp^X = C₅Me ₄, C₅H₃tBu, R = Ph, Me) is presented. Two of the lithium complexes were characterized by means of single-crystal X-ray analysis, revealing a dimeric head-to-tail arrangement in the solid state. The coordination behavior of 9-12 in the liquid phase is solvent dependent. These lithium phosphonium diylides exist as contact ion pairs in benzene and as solvent-separated ion pairs in THF solutions. Phosphonium salts [H ₃C-PR₂-Cp^XH)]⁺I^- (1-4) are starting materials for the syntheses of the title compounds and exist as mixtures of isomers due to [1,5]-prototropic rearrangements. The dynamic behavior in solution has been investigated. Two different routes allow access to title compounds 9-12. Reactions of 1-4 with 2 equiv of nBuLi give 9-12 in a one-pot synthesis. In an alternative two-step route, dehydrodehalogenation of 1-4 with KH gives the corresponding phosphonium ylides 5-8. Two of these phosphonium ylides were characterized by single-crystal X-ray analysis. In one case two different conformers were obtained.

Full text of DOI:10.1021/om201182y

Article
pubs.acs.org/Organometallics
New Lithium Phosphonium Diylides: A Methylene and a
Cyclopentadienyl Moiety as Ylidic Coordination Sites
Crispin Lichtenberg,† Nina S. Hillesheim, Michael Elfferding, Benjamin Oelkers, and Jorg Sundermeyer*
̈
Fachbereich Chemie der Philipps-Universitat Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
̈
S
* Supporting Information
ABSTRACT: A set of lithium phosphonium diylides Li[CH2-
PR2-CpX] (9−12; CpX = C5Me4, C5H3tBu, R = Ph, Me) is
presented. Two of the lithium complexes were characterized
by means of single-crystal X-ray analysis, revealing a dimeric
head-to-tail arrangement in the solid state. The coordination
behavior of 9−12 in the liquid phase is solvent dependent.
These lithium phosphonium diylides exist as contact ion pairs
in benzene and as solvent-separated ion pairs in THF solutions. Phosphonium salts [H3C-PR2-CpXH)]+I− (1−4) are starting
materials for the syntheses of the title compounds and exist as mixtures of isomers due to [1,5]-prototropic rearrangements. The
dynamic behavior in solution has been investigated. Two different routes allow access to title compounds 9−12. Reactions of 1−
4 with 2 equiv of nBuLi give 9−12 in a one-pot synthesis. In an alternative two-step route, dehydrodehalogenation of 1−4 with
KH gives the corresponding phosphonium ylides 5−8. Two of these phosphonium ylides were characterized by single-crystal X-
ray analysis. In one case two different conformers were obtained.
point of view, type C ligands also allowed for the first structural
characterization of a noncoordinated phosphonium diylide.9 In
sharp contrast to the plethora of literature on organometallic
compounds with phosphonium diylide ligands of types A and
C, the hybrid ligand system of type B (CpPC ligand, Scheme 1)
has scarcely been investigated. In fact, there is only a single
publication on this kind of ligand system.10 The authors
reported on type B phosphonium diylide (CpPC) complexes of
sodium, in which the ligand system had an indenyl group
instead of a Cp moiety and electron-withdrawing substituents
attached to the second ylide functionality. Due to its electron-
poor nature, the second ylide moiety does not interact with the
metal center in the only structurally authenticated example.
Herein, we report the synthesis and characterization of a
series of lithiated CpPC ligands, which bear an unsubstituted
methylene functionality, keeping their metal coordinating
character intact.
INTRODUCTION
■
Phosphonium diylides have a longstanding tradition as
monoanionic, bidentate ligands in organometallic chemistry
(Scheme 1, A).1 Complexes of this versatile ligand system with
Scheme 1. Set of Isoelectronic, Monoanionic, Bidentate
Phosphonium Diylide Ligands: Classical (A), Cp Substituted
(CpPC Type Ligand, B), and bis-Cp Substituted (C) (R =
Alkyl, Aryl)
metals across the entire periodic table have been studied2
covering a broad spectrum of research interests, such as metal−
metal interactions,3 the development of pharmaceuticals,4 new
synthetic methods in organic chemistry,5 and catalytic
applications.3a,f,6 Within this field, polynuclear gold complexes
in particular have to be mentioned. This class of compounds is
sufficiently stabilized by type A ligands, and their characteristics
and reactivity have been investigated.3a−f,7
Not only the classical phosphonium diylides themselves have
received considerable scientific interest but also a set of
phosphonium-bridged ansa-metallocene ligands, which are
formally derived thereof (Scheme 1, C). Main-group and
transition-metal complexes based on type C ligands have been
prepared and in some cases applied successfully as catalysts or
as substrates in polymerization reactions.8 From an academic
RESULTS AND DISCUSSION
■
The desired CpPC ligand systems can be derived from
cyclopentadienyl-substituted phosphanes in a straightforward
protocol. A variety of this small class of compounds is accessible
with different substitution patterns both at the phosphorus
atom and at the cyclopentadienyl moiety.11 This allows for
tuning of the electronic and steric parameters of the future
ligand system.
Phosphonium Salts. Four phosphanes were chosen as
representative starting materials (R2P-CpX: R = Me, Ph, CpX =
C5HMe4, C5H4tBu). Quaternization of these phosphanes with
Received: March 20, 2012
Published: May 25, 2012
© 2012 American Chemical Society
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methyl iodide leads to the phosphonium salts 1−4 in good
of 5 (5a and 5b) and 6 have been characterized by means of
single-crystal X-ray analysis (Figure 1). In compound 5, there is
one major structural difference between the two modifications
5a and 5b: the torsion angle C2−C1−P1−C10/11/17 reaches
its minimum for C17 (which is part of a phenyl substituent) in
the case of 5a and for C10 (which is part of a methyl group) in
the case of 5b. 6 crystallizes with two chemically equivalent but
crystallographically independent molecules in the asymmetric
unit. The P−CCp bonds in 5a,b and 6 can be described by
significant contributions of both the ylide and the ylene
resonance structure.13 This is in agreement with earlier reports
on comparable systems14 and can be supported by two
structural parameters. (i) The P−CCp bonds (1.717(2)−
1.735(3) Å) are significantly longer than the corresponding
bonds in nonstabilized phosphonium ylides (e.g., 1.661 Å in
Ph3PCH2)15 but considerably shorter than P−C single
bonds.16 (ii) Within the cyclopentadienyl substituent there are
two long, one medium, and two short C−C bond distances, all
of which range between values known for single and double C−
C bonds.17
yields (Scheme 2). They exist as a mixture of isomers due to
Scheme 2. Synthesis of Cp-Substituted Phosphonium Salts,
Which Exist as Mixtures of Isomers: 1, R1 = Ph, R2, R3 = Me;
2, R1, R2, R3 = Me; 3, R1 = Ph, R2 = H, R3 = tBu; 4, R1 = Me,
R2 = H, R3 = tBu
[1,5]-prototropic rearrangements. These isomerization pro-
cesses were investigated by means of NMR spectroscopy (for
details see the Supporting Information):
Phosphonium Ylides. Dehydrodehalogenation of phos-
phonium salts 1−4 with potassium hydride gives the
phosphonium ylides 5−8 (Scheme 3, left).12 Two conformers
Phosphonium Diylides. Deprotonation of the ylides 5−8
gives the desired CpPC ligands. However, the formation of
detectable amounts of alkali-metal phosphonium diylides was
not observed when 5−8 were exposed to excess potassium
hydride and long reaction times were applied. In contrast, the
only so far fully characterized complex with a CpPC type ligand
is accessible by deprotonation of the corresponding ylide with
an alkali-metal hydride. This reveals the higher acidity of this
formerly reported ylide in comparison to 5−8. In turn, CpPC
ligands derived from 5−8 can be expected to show a stronger
electron-donating character. Reaction of 5−8 with the strong
base nBuLi allowed for the synthesis of lithium phosphonium
diylides 9−12 (Scheme 3, bottom). These compounds can also
be obtained from phosphonium salts 1−4 in a one-pot reaction
which combines a dehydrodehalogenation and a deprotonative
metalation (Scheme 3, right).
Scheme 3. Two-Step (Left and Bottom) and One-Pot
Syntheses (Right) of a Series of Lithium Phosphonium
Diylides (9−12)
Compounds 9−12 are readily soluble in THF, diethyl ether,
or benzene and modestly soluble in pentane or hexane.
Figure 1. Molecular structures of 5 (5a, left; 5b, middle) and 6 (right). There are two crystallographically independent but chemically equivalent
molecules in the asymmetric unit of 6. One of them shows a crystallographic disorder in the PMe3 unit and is not displayed. Structural parameters of
motifs analogous to those of the molecule displayed above are given in parentheses. Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å), bond angles (deg), and torsion angles (deg) are as follows. 5a: P1−C1, 1.720(2);
P1−C10, 1.797(3); P1−C11, 1.815(3); P1−C17, 1.807(2); C1−C2, 1.439(4); C2−C3, 1.394(4); C3−C4, 1.420(4); C4−C5, 1.378(4); C5−C1,
1.443(4); C1−C2−C3, 106.8(2); C2−C3−C4, 109.1(2); C3−C4−C5, 109.1(2); C4−C5−C1, 107.4(2); C5−C1−C2, 107.6(2); C17−P1−C1−
C2, 17.6(3); C17−P1−C1−C5, 176.5(2). 5b: P1−C1, 1.717(2); P1−C10, 1.791(2); P1−C11, 1.815(2); P1−C17, 1.810(2); C1−C2, 1.448(3);
C2−C3, 1.375(3); C3−C4, 1.432(3); C4−C5, 1.376(3); C5−C1, 1.440(3); C1−C2−C3, 107.1(2); C2−C3−C4, 109.4(2); C3−C4−C5, 108.5(2);
C4−C5−C1, 107.8(2); C5−C1−C2, 107.3(2); C10−P1−C1−C2, 5.8(2); C10−P1−C1−C5−C9, 177.4(2). 6: P1−C1, 1.725(3) (1.735(3)); P1−
C10, 1.816(4) (1.780(26)); P1−C11, 1.773(4) (1.749(19)); P1−C17, 1.774(4) (1.804(26)); C1−C2, 1.433(4) (1.436(4)); C2−C3, 1.389(4)
(1.395(4)); C3−C4, 1.418(4) (1.421(4)); C4−C5, 1.388(4) (1.399(3)); C5−C1, 1.444(4) (1.441(4)); C1−C2−C3, 107.6(2) (107.8(2)); C2−
C3−C4, 109.0(2) (108.6(2)); C3−C4−C5 108.7(2) (108.6(2)); C4−C5−C1, 107.5(2) (108.0(2)); C5−C1−C2, 107.2(2) (107.0(2)); C10−P1−
C1−C2, 3.4(3) (23.5(9)); C10−P1−C1−C5, 177.7(2) (161.8(8)).
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Interactions of the CpPC ligands in 9−12 with the metal center
have been investigated in solution. The methylene group and
the cyclopentadienyl moiety in each of these ligands are the
donor sites which might interact with the alkali metal. Whereas
no close Li−C(methylene) or Li−CpX (CpX = C5Me4 for 9 and
10; CpX = C5H3tBu for 11 and 12) contacts were detected in
solutions of 9−12 in the polar solvent THF, both
functionalities show interactions with Li centers in solutions
of 9−12 in the nonpolar solvent benzene. Interactions of the
methylene functionality with the lithium center were studied by
13C NMR spectroscopy. In absence of Li−C(methylene)
interactions, the methylene carbon atom gives rise to a doublet
in the 13C NMR spectrum due to 1JCP coupling. Indeed, a signal
with the expected multiplicity is observed in 13C NMR spectra
of THF solutions of 9−12 (Figure 2 (left) for 9 as a
coordinating solvent THF (Table 1). Solvent-separated ion
pairs of phosphonium diylides in solution (and in the solid
state) have been reported previously for complexes of calcium
and barium, which have a higher tendency than lithium to form
ionic structures.9 However, detailed studies concerning C−Li
bonding of type A or C lithium phosphonium diylides (Scheme
1) in solution have not been reported so far.1b,8c Thus, this is
the first study providing a more profound insight into the
metal−ligand interactions of lithium phosphonium diylides in
solution.19
Lithium complexes of phosphonium diylides have been
known since the early days of this class of compounds and have
been used as transmetalation reagents ever since.1a,20 However,
they have eluded structural characterization for more than three
decades.21 Only three such compounds have been analyzed by
means of single-crystal X-ray analysis to date.21,22 Single crystals
of compounds 9 and 11 were obtained from solutions in
pentane and hexane, respectively, at lowered temperatures.
They both crystallize in the triclinic space group P1 with two
̅
crystallographically independent formula units per asymmetric
unit. The molecular structures of the two compounds exhibit
similar structural parameters and will be discussed together. 9
and 11 both form dimers with a head-to-tail arrangement in the
solid state (Figure 3).23 The lithium atoms in 9 and 11 are
coordinated by an η5-Cp moiety and a methylene group. No
donor solvent molecules are bound to the Li centers, which
underlines the good electron-donating character of the two
ylidic coordination sites in the CpPC ligand system.24
Cpcentroid−Li−C bond angles range from 163.8(1) to
173.5(2)°. The slight bending was ascribed to geometric
constraints dictated by the dimeric arrangement. The Li−
C(methylene) bonds of 2.091(3)−2.112(3) Å are marginally
shortened in comparison to the corresponding bonds in the
other three crystallographically characterized lithium phospho-
nium diylides.21,22 This was ascribed to the fact that further
neutral donor ligands are attached to the metal center in the
latter cases. The Li−Cpcentroid distances range from 1.847(2) to
1.866(2) Å (in the case of 9) and from 1.880(4) to 1.912(3) Å
(in the case of 11). The stronger electron-donating character of
the C5Me4 fragment and the higher steric bulk of the C5H3tBu
moiety explain the shorter Li−Cpcentroid distances in the former
case. All these values are in the range of known Li−Cpcentroid
distances in lithium complexes with an η5-Cp motif.25 The C−
C bond lengths in the Cp fragments in 9 and 11 are between
values expected for single and double bonds, indicating the
presence of a delocalized π-electron system. All phosphorus
atoms in these compounds are found in a distorted-tetrahedral
coordination geometry (C−P−C, 102.9(1)−116.0(1)°). Com-
pounds 9 and 11 represent lithium cyclopentadienyl derivatives
with an additional neutral coordination site attached to the Cp
fragment. Complexes known in the literature which also belong
to this small class of compounds usually form oligomeric
structures in the solid state.26 Thus, a dimeric arrangement as
observed in the case of 9 and 11 is unprecedented for such
compounds. In comparison to other lithium phosphonium
diylides, it is remarkable that 9 and 11 can be obtained without
additional neutral ligands bound to the metal center.21,22
Preliminary reactivity studies concerning transmetalation
reactions of the CpPC ligand are promising. Reaction of 9
with CuCl gives the analogous copper complex Cu[CH2-PPh2-
C5Me4)] (13), which was characterized spectroscopically
(Scheme 4).27 The full potency of transmetalation reactions
Figure 2. Signals in 13C NMR spectra due to carbon atom of the
methylene moiety of 9 in THF-d8 (doublet, left) and C6D6 (broad
signal, right).
representative example). In the case of Li−C(methylene)
contacts, the methylene carbon atom in 9−12 theoretically
gives rise to a doublet of triplets overlapped by a doublet of
quartets in the 13C NMR spectrum due to the presence of 31P
(I = 1/2, N = 100%), 6Li (I = 1, N = 7.4%), and 7Li nuclei (I =
3/2, N = 92.6%). In fact, the multiplet is not fully resolved and a
broad signal is observed for the methylene carbon atom in 13C
NMR spectra of C6D6 solutions of 9−12, providing evidence of
interactions between the methylene moiety and the metal
center (Figure 2 (right) for 9 as a representative example).
Interaction of the CpX moieties with Li centers was studied
by 7Li NMR spectroscopy according to the method established
by Cox et al.18 High-field Li NMR chemical shifts for lithium
7
cyclopentadienyl compounds are indicative of contact ion pairs
to be formed, whereas low-field chemical shifts prove the
presence of solvent-separated ion pairs (see reference data for
LiCp in Table 1). The data for 9−12 provide evidence of
contact ion pairs formed in noncoordinating solvents such as
pentane and benzene and separated ion pairs present in the
7
Table 1. Solvent Dependence of Chemical Shift in Li NMR
Spectra of LiCp (Cox et al.)18 and 9−12 (This Work)
chem shift (7Li NMR)/ppm
a
compd
pentane
benzene
THF
HMPT
9
−5.20
−5.92
−5.98
−6.62
−5.54
−6.36
−5.89
−7.02
−0.89
1.11
10
11
12
LiCp
0.92
−2.39
−8.37
−0.88
a
HMPT = OP(NMe2)3.
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Figure 3. Dimeric arrangements in molecular structures of 9 (left) and 11 (right). There are two crystallographically independent but chemically
equivalent molecules in the asymmetric unit of 9, only one of which is displayed (structural parameters of analogous motifs are given in parentheses).
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen atoms are omitted for clarity. Selected bond lengths (Å), bond angles (deg), and
torsion angles (deg) are as follows. 9: Li1−Cpcentroid, 1.866(2) (1.847(2)); Li1−C10′, 2.112(3) (2.091(3)); P1−C1, 1.762(2) (1.768(3)); P1−C10,
1.724(2) (1.726(2)); P1−C11, 1.825(1) (1.820(1)); P1−C17, 1.809(1) (1.819(2)); C1−C2, 1.439(2) (1.436(2)); C2−C3, 1.397(2) (1.406(2));
C3−C4, 1.421(2) (1.416(2)); C4−C5, 1.404(2) (1.399(2)); C1−C5, 1.441(2) (1.441(2)); Cpcentroid−Li1−C10′, 167.7(1) (163.8(1)); C1−P1−
C10, 114.7(7) (113.0(1)); C1−P1−C11, 104.9(1) (106.0(1)); C1−P1−C17, 111.2(1) (112.0(1)); C10−P1−C11, 116.0(1) (115.7(1)); C10−P1−
C17, 104.7(1) (105.8(1)); C11−P1−C17, 104.9(1) (104.3(1)). 11: Li1−Cpcentroid, 1.880(4); Li1−C44, 2.099(4); P1−C1, 1.774(2); P1−C10,
1.811(2); P1−C16, 1.824(2); P1−C22, 1.708(3); C1−C2, 1.411(3); C2−C3, 1.402(3); C3−C4, 1.405(3); C4−C5, 1.392(3); C1−C5, 1.419(3);
Li2−Cpcentroid, 1.912(3); Li2−C22, 2.106(4); P2−C23, 1.763(2); P2−C32, 1.823(2); P2−C38, 1.809(2); P2−C44, 1.726(2); C23−C24, 1.428(3);
C24−C25, 1.401(3); C25−C26, 1.419(3); C26−C27, 1.397(3); C23−C27, 1.417(3); Cpcentroid−Li1−C44, 172.5(2); C1−P1−C10, 107.6(1); C1−
P1−C16, 106.8(1); C1−P1−C22, 112.1(1); C10−P1−C16, 102.9(1); C10−P1−C22, 111.6(1); C16−P1−C22, 115.2(1); Cpcentroid−Li2−C22,
165.2(2); C23−P2−C32, 107.5(1); C23−P2−C38, 106.7(1); C23−P2−C44, 112.6(1); C32−P2−C38, 103.7(1); C32−P2−C44, 114.8(1); C38−
P2−C44, 110.1(1).
with the CpPC ligand system is currently being exploited in our
laboratories.
only other fully characterized CpPC complex,10 both
coordination sites in 9 and 11 interact with the metal center.
The coordination properties of the CpPC ligands in solution
are solvent dependent. Whereas no close interactions with the
metal center were found in solutions of the coordinating
solvent THF, the methylene and the cyclopentadienyl moiety
interact with the alkali metal in solutions of the weakly
coordinating solvent benzene.
a
Scheme 4. Synthesis of Copper Complex 13
EXPERIMENTAL SECTION
■
General Remarks. All experimental procedures were carried out
under an atmosphere of purified argon or nitrogen using standard
Schlenk techniques or a glovebox. The solvents used were dried and
degassed according to standard protocols. Chemicals were purchased
from Alfa Aesar or Aldrich and used without further purification. 6 was
synthesized according to the literature.28 NMR measurements were
performed using a Bruker DPX 250, AVANCE 300, DRX 400, or DRX
a
We suggest a dimeric arrangement of this complex in the solid state.27
500 spectrometer at 25 °C. The chemical shifts of H and 13C NMR
1
spectra were referenced internally using the residual solvent
resonances and are reported relative to the chemical shift of
CONCLUSION
■
A series of monoanionic, bidentate phosphonium diylide
ligands with a methylene and a cyclopentadienyl group as
coordination sites (CpPC ligands) is reported. The lithium
complexes Li[CH2-PR2-CpX] (9−12: CpX = C5Me4, C5H3tBu;
R = Ph, Me) are accessible in a one-pot synthesis from the
corresponding phosphonium iodides 1−4. The phosphonium
salts 1−4 exist as mixtures of isomers due to [1,5]-prototropic
rearrangements. 9−12 are also accessible in a two-step
synthesis from 1−4. The products of the first step,
phosphonium ylides 5−8, have been isolated and characterized,
two of them by means of single crystal X-ray analysis. Two
conformers of one of the phosphonium ylides were obtained.
Single-crystal X-ray analysis of lithium complexes 9 and 11
revealed a dimeric head-to-tail arrangement. In contrast to the
1
tetramethylsilane. The resonances in H and 13C NMR spectra were
assigned on the basis of two-dimensional NMR experiments (COSY,
7
HMQC, HMBC). The Li and 31P NMR resonances are reported
relative to external standards, an aqueous solution of LiCl and
phosphoric acid (85%), respectively. Elemental analyses were carried
out at the Analytical Laboratory of the Department of Chemistry/
Philipps-Universitat Marburg. EI mass spectra were recorded using a
̈
Finnigan MAT CH7 instrument (E = 70 eV). ATR FT IR spectra were
obtained using a Bruker Alpha-P spectrometer. For details concerning
the synthesis of phosphonium salts 1−4 see the Supporting
Information.
Phosphonium Ylides 5, 7, and 8. The phosphonium salt (1, 3.90
g, 8.70 mmol; 3, 1.10 g, 2.47 mmol; 4, 6.50 g, 20.0 mmol) was
suspended in THF (40−180 mL), and KH (in the case of 1, 0.484 g,
12.1 mmol; in the case of 3, 0.136 g, 3.39 mmol; in the case of 4, 1.14
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g, 28.4 mmol) was added. The liquid phase subsequently turned
yellow. After 2 days the reaction mixture was filtered and the residue
was washed with diethyl ether (3 × 5 mL). All volatiles were removed
from the filtrate to give a yellow (in the case of 5), beige (in the case of
7), or colorless solid (in the case of 8). 7 was recrystallized from THF
solution at −30 °C. Yield: 5, 2.57 g, 8.01 mmol, 92%; 7, 0.628 g, 1.96
mmol, 79%; 8, 3.28 g, 16.7 mmol, 82%.
16.8 Hz, 3-C5H4tBu) ppm. 31P NMR (121.5 MHz, C6D6): δ −4.24
ppm. 31P NMR (121.5 MHz, THF-d8): δ −2.19 ppm. EI/MS: m/z
(%) 196 (24) [M]+, 181 (100) [(M − CH3)+]. Anal. Calcd for
C12H21P (196.27 g/mol): C, 73.43; H, 10.78. Found: C, 72.81; H,
10.31. IR: 2974 (m), 2943 (m), 2903 (m), 1290 (w), 1202 (m), 1176
(w), 1093 (m), 978 (m), 952 (m), 941 (m), 909 (m), 863 (w), 767
(s), 746 (w), 687 (w), 662 (s), 609 (w) cm−1.
Phosphonium Diylides 9−12. Method A. A solution of the
phosphonium ylide (5, 250 mg, 0.78 mmol; 6, 101 mg, 0.52 mmol; 7,
157 mg, 0.49 mmol; 8, 77 mg, 0.39 mmol) in diethyl ether (5 mL) was
cooled to −78 °C and treated with a solution of nBuLi in hexane (1.6
M: in the case of 5, 485 μL, 0.78 mmol; in the case of 6, 325 μL, 0.52
mmol; in the case of 7, 305 μL, 0.49 mmol; in the case of 8, 245 μL,
0.39 mmol). After 1 h the reaction mixture was warmed to ambient
temperature. All volatiles were removed under reduced pressure. The
residue was suspended in pentane (10 mL), and the supernatant was
decanted after centrifugation. The process was repeated. All volatiles
were removed from the combined liquid phases under reduced
pressure to give a beige solid, which was dried in vacuo. Yield: 9, 235
mg, 0.72 mmol, 92%; 10, 61 mg, 0.30 mmol, 58%; 11, 146 mg, 0.45
mmol, 91%; 12, 53 mg, 0.26 mmol, 67%.
Method B. A suspension of the phosphonium salt (1, 623 mg, 1.39
mmo; 2, 162 mg, 0.50 mmol; 3, 155 mg, 0.35 mmol; 4, 150 mg, 0.46
mmol) in diethyl ether (5−10 mL) was cooled to −78 °C. A solution
of nBuLi in hexane (1.6 M: in the case of 1, 1.74 mL, 2.78 mmol; in
the case of 2, 0.625 μL, 1.0 mmol; in the case of 3, 440 μL, 0.70 mmol;
in the case of 4, 575 μL, 0.46 mmol) was added. The reaction mixture
was warmed to ambient temperature over a period of 2 h. All volatiles
were removed under reduced pressure. The residue was suspended in
pentane (10 mL), filtered, and washed with pentane (2 × 5 mL). All
volatiles were removed from the combined liquid phases to give a
beige solid, which was dried in vacuo. Yield: 9, 290 mg, 0.89 mmol,
64%; 10, 86 mg, 0.40 mmol, 87%; 11, 53 mg, 0.26 mmol, 67%; 12, 86
mg, 0.43 mmol, 93%.
MePh2PC5Me4 (5). 1H NMR (300.1 MHz, C6D6): δ 1.70 (d, 2JHP
=
12.8 Hz, 3H, PMe), 2.10 (s, 6H, 2,5-CpMe2), 2.49 (s, 6H, 3,4-CpMe2),
6.91−6.96 (m, 4H, o-/m-Ph), 6.99−7.04 (m, 2H, p-Ph), 7.28−7.35
1
(m, 4H, m-/o-Ph) ppm. H NMR (300.1 MHz, THF-d8): δ 1.70 (s,
6H, 2,5-CpMe2), 1.88 (s, 6H, 3,4-CpMe2), 2.34 (d, 2JHP = 13.1 Hz, 3H,
PMe), 7.45−7.49 (m, 4H, o-Ph), 7.52−7.55 (m, 2H, p-Ph) 7.57−7.64
1
(m, 4H, m-Ph) ppm. H NMR (300.1 MHz, Py-d5): δ 1.99 (s, 6H,
2
2,5-/3,4-CpMe2), 2.26 (s, 6H, 3,4-/2,5-CpMe2), 2.36 (d, JHP = 13.0
Hz, 3H,PMe), 7.35−7.40 (m, 4H, o-/m-Ph), 7.46−7.50 (m, 2H, p-Ph),
7.66−7.72 (m, 4H, m-/o-Ph) ppm. 13C NMR (75.5 MHz, C6D6): δ
1
12.2 (s, 3,4-CpMe2), 14.5 (s, 2,5-CpMe2), 15.2 (d, JCP = 61.4 Hz,
1
2
PMe), 68.4 (d, JCP = 111.4 Hz, 1-Cp), 119.2 (d, JCP = 15.5 Hz, 2,5-
Cp), 121.4 (d, 3JCP = 18.4 Hz, 3,4-Cp), 128.8 (d, 2/3JCP = 11.8 Hz, o-/
m-Ph), 130.7 (d, 1JCP = 130.7 Hz, ipso-Ph), 131.7 (d, 4JCP = 2.7 Hz, p-
3/2
Ph), 132.8 (d,
J
= 10.2 Hz, m-/o-Ph) ppm. 13C NMR (100.0
CP
4
MHz, THF-d8): δ 11.6 (d, JCP = 2.8 Hz, 3,4-CpMe2), 14.9 (s, 2,5-
1
1
CpMe2), 15.2 (d, JCP = 61.6 Hz, PMe), 69.1 (d, JCP = 111.0 Hz, 1-
2
3
Cp), 118.8 (d, JCP = 15.2 Hz, 2,5-Cp), 120.1 (d, JCP = 18.4 Hz, 3,4-
2/3
1
Cp), 129.4 (d,
J
= 11.7 Hz, o-/m-Ph), 131.4 (d, JCP = 83.9 Hz,
CP
ipso-Ph), 132.3 (d, 4JCP = 2.7 Hz, p-Ph), 133.4 (d, 3/2JCP = 10.3 Hz, m-/
o-Ph) ppm. 31P NMR (121.5 MHz, C6D6): δ 2.1 ppm. 31P NMR
(121.5 MHz, THF-d8): δ 2.8 ppm. 31P NMR (121.5 MHz, Py-d5): δ
3.2 ppm. Anal. Calcd for C22H25P (320.41 g/mol): C, 82.47; H, 7.86.
Found: C, 81.98; H, 8.25. EI/MS (70 eV): m/z (%) 320 (43) [M·+],
305 (18) [(M − Me)+], 281 (100). HR-EI/MS (70 eV): m/z (%)
320.1686 (56) [M·+]. IR: 2939 (w), 2900 (m), 2845 (m), 1435 (s),
1278 (s), 1151 (m), 1103 (m), 1027 (m), 997 (m), 889 (s), 751 (s),
741 (s), 692 (s), 510 (s), 487 (s), 465 (s), 453 (s) cm−1.
In methods A and B, diethyl ether can be substituted for THF. In all
cases the isolated compounds must be dried in vacuo for several hours
or recrystallized from pentane to remove the last 1 equiv of the donor
solvent molecule (Et2O or THF).
MePh2PC5H3tBu (7). 1H NMR (300.1 MHz, CDCl3): δ 1.29 (s, 9H,
2
tBu), 2.56 (d, JHP = 12.0 Hz, 3H, PMe), 6.10−6.09 (m, 2H, 4,5-
C5H3tBu), 6.31(m, 1H, 2-C5H3tBu), 7.64−7.55 (m, 10H, PPh2) ppm.
1H NMR (300.1 MHz, C6D6): δ 1.67 (s, 9H, tBu), 1.76 (d, 2JHP = 15.0
Hz, 3H, PMe), 6.38−6.43 (m, 2H, C5H3tBu), 7.35−6.85 (m, 10H,
PPh2; 1H, C5H3tBu) ppm. 1H NMR (400.1 MHz, THF-d8): δ 1.21 (s,
1
[(Li-CH2-PPh2-C5Me4)2] (9). H NMR (300.1 MHz, C6D6): δ 0.15
(d, 2JHP = 11.4 Hz, 2H, PCH2Li), 1.27−1.31 (m, 4H, β-THF), 1.89 (s,
6H, 3,4-CpMe2), 2.29 (s, 6H, 2,5-CpMe2), 3.79−3.83 (m, 4H, α-
THF), 7.03 (br s, 6H, m-/o-,p-Ph), 7.62−7.67 (m, 4H, o-/m-Ph) ppm.
2
9H, tBu), 2.33 (d, JHP = 12.0 Hz, 3H, PMe), 5.76−5.91 (m, 2H,
2
1H NMR (400.0 MHz, THF-d8): δ 0.08 (d, JHP = 11.2 Hz, 2H,
C5H3tBu), 6.07 (m, 1H, C5H3tBu), 7.24−7.66 (m, 10H, PPh2) ppm.
13C NMR (75.5 MHz, CDCl3): δ 12.5 (d, 1JCP = 62.2 Hz, PMe). 30.7
PCH2), 1.57 (s, 6H, 3,4-CpMe2), 1.75−1.79 (m, 4H, β-THF), 1.88 (s,
6H, 2,5-CpMe2), 3.60−3.64 (m, 4H, α-THF), 7.23−7.30 (m, 6H, m-/
o-,p-Ph), 7.61−7.65 (m, 4H, o-/m-Ph) ppm. 13C NMR (100.6 MHz,
1
(s, C(CH3)3), 32.5 (s, C(CH3)3), 80.2 (d, JCP = 118.9 Hz, 1-
C5H3tBu), 109.2 (d, 2JCP = 14.9 Hz, 2-C5H3tBu), 110.3 (d, 3JCP = 15.5
Hz, 4-C5H3tBu), 113.6 (d, 2JCP = 14.4 Hz, 5-C5H3tBu), 125.7 (d, 1JCP
=
C6D6) δ −1.2 (br s, CH2Li), 10.8 (d, 3JCP = 1.3 Hz, 2,5-CpMe2), 12.9
89.4 Hz, ipso-Ph), 129.2 (d, 2JCP = 12.4 Hz, o-Ph), 132.5 (d, 3JCP = 10.6
Hz, m-Ph), 133.2 (d, 4JCP = 2.8 Hz, p-Ph), 142.4 (d, 3JCP = 15.3 Hz, 3-
C5H3tBu) ppm. 13C NMR (62.5 MHz, THF-d8): δ 12.0 (d, 1JCP = 62.5
Hz, PMe), 32.6 (s, C(CH3)3), 33.2 (s, C(CH3)3), 89.4 (d, 1JCP = 120.0
1
(s, 3,4-CpMe2), 25.1 (s, β-THF), 68.8 (s, α-THF), 92.0 (d, JCP
=
=
2
3
114.6 Hz, 1-Cp), 115.5 (d, JCP = 12.2 Hz, 2,5-Cp), 116.0 (d, JCP
3/2
13.6 Hz, 3,4-Cp), 128.2 (d,
= 2.0 Hz, p-Ph), 132.4 (d,
J
= 10.9 Hz, m-/o-Ph), 130.3 (d, 4JCP
CP
2/3
1
J
= 9.6 Hz, o-/m-Ph), 136.2 (d, JCP
=
CP
Hz, 1-C5H3tBu), 107.9 (d, 2JCP = 15.0 Hz, 2-C5H3tBu), 109.4 (d, 3JCP
=
76.3 Hz, ipso-Ph) ppm. 13C NMR (100.6 MHz, THF-d8) δ 0.7 (d, 1JCP
2
3
16.3 Hz, 4-C5H3tBu), 113.2 (d, JCP = 14.4 Hz, 5-C5H3tBu), 129.3 (d,
= 41.2 Hz, PCH2), 11.5 (d, JCP = 1.7 Hz, 2,5-CpMe2), 14.0 (s, 3,4-
CpMe2), 26.3 (s, β-THF), 68.2 (s, α-THF), 87.3 (d, JCP = 117.6 Hz,
4JCP = 2.5 Hz, p-Ph), 129.3 (d, 3JCP = 11.8 Hz, m-Ph), 133.2 (d, 2JCP
=
1
3/2
3
1-Cp), 115.5 (s, 2,5-/3,4-Cp), 115.7 (d, 3,4-/2,5-Cp), 128.1 (d,
J
10.6 Hz, o-Ph), 137.0 (d, JCP = 15.0 Hz, 3-C5H3tBu) ppm. A
resonance due to the ipso-Ph carbon atoms was not detected. 31P
NMR (121.5 MHz, C6D6): δ 4.46 ppm. 31P NMR (121.5 MHz, Et2O):
δ 5.79 ppm. 31P NMR (161.9 MHz, THF-d8): δ 6.40 ppm. EI/MS: m/
z (%) 320.2 (21%) [M+], 305.1 (100) [(M − CH3)+]. IR: 2951 (w),
2896 (m), 1202 (m), 1090 (m), 880 (m), 740 (s), 689 (s), 666 (s),
530 (m), 499 (s), 465 (s), 450 (s) cm−1.
CP
=
= 10.5 Hz, m/o-Ph), 129.8 (d, 4JCP = 2.0 Hz, p-Ph), 133.1 (d, 2/3JCP
9.5 Hz, o-/m-Ph), 140.2 (d, JCP = 74.0 Hz, ipso-Ph) ppm. 31P NMR
(162.0 MHz, pentane): δ 23.1 ppm. 31P NMR (162.0 MHz, C6D6): δ
1
22.3 ppm. 31P NMR (162.0 MHz, THF-d8): δ 21.0 ppm. Li NMR
7
(155.5 MHz, pentane): δ −5.20 ppm. 7Li NMR (155.5 MHz, C6D6): δ
−5.54 ppm. 7Li NMR (155.5 MHz, THF-d8): δ −0.89 ppm. IR: 3051
(w), 2951 (m), 2904 (m), 2853 (m), 1480 (s), 1304 (s), 1097 (s), 858
(s), 690 (s), 522 (s), 490 (s) cm−1.
1
2
Me3PC5H3tBu (8). H NMR (300.1 MHz, C6D6): δ 0.72 (d, JHP
=
13.2 Hz, 9H, PMe3), 1.72 (s, 9H, tBu), 6.21 (m, 1H, C5H3tBu), 6.37
[(Li-CH22-PMe2-C5Me4)2] (10). 1H NMR (300.1 MHz, C6D6): δ
1
(m, 1H, C5H3tBu), 6.78 (m, 1H, C5H3tBu) ppm. H NMR (300.1
2
2
MHz, THF-d8): δ 1.19 (s, 9H, tBu), 1.69 (d, JHP = 13.6 Hz, 9H,
−0.46 (d, JHP = 11.7 Hz, 2H, PCH2Li), 1.16 (d, JHP = 12.1 Hz, 6H,
1
PMe3), 5.96−5.88 (m, 3H, C5H4tBu) ppm. 13C NMR (75.5 MHz,
PMe2), 2.20 (s, 6H, 3,4-CpMe2), 2.25 (s, 6H, 2,5-CpMe2) ppm. H
1
4
2
C6D6): δ 13.2 (d, JCP = 59.6 Hz, PMe3), 32.7 (d, JCP = 1.7 Hz,
NMR (250 MHz, THF-d8): δ −0.56 (d, JHP = 7.5 Hz, 2H, PCH2),
C(CH3)3), 33.6 (s, C(CH3)3), 79.2 (d, JCP = 113.3 Hz, 1-C5H3tBu),
106.1 (d, JCP = 16.7 Hz, 4-C5H4tBu), 111.7 (d, JCP = 17.9 Hz, 2-/5-
C5H4tBu), 111.9 (d, JCP = 16.2 Hz, 2-/5-C5H4tBu), 141.1 (d, JCP
1.51 (d, 2JHP = 12.5 Hz, 6H, PMe2), 1.88 (s, 6H, 3,4-CpMe2), 2.13 (s,
6H, 2,5-CpMe2) ppm. 13C NMR (62.5 MHz, THF-d8): δ 4.75 (d, 1JCP
= 44.4 Hz, PCH2), 11.39 (d, 4JCP = 1.88 Hz, 2,5-CpMe2), 14.12 (s, 3,4-
1
3
2
2
3
=
4263
dx.doi.org/10.1021/om201182y | Organometallics 2012, 31, 4259−4266

Organometallics
Article
3/2
CpMe2), 22.76 (d, 1JCP = 51.3 Hz, PMe2), 91.7 (d, 1JCP = 108.1 Hz, 1-
Cp), 113.7 (d, JCP = 13.1 Hz, 3,4-Cp), 114.3 (d, JCP = 14.4 Hz, 2,5-
Cp) ppm. 31P NMR (121.5 MHz, C6D6): δ 10.3 ppm. 31P NMR
(161.9 MHz, THF-d8): δ 5.1 ppm. 7Li NMR (155.4 MHz, pentane): δ
Hz, 3,4/2,5-Cp), 118.1 (d,
J
= 14.3 Hz, 2,5-/3,4-Cp), 128.5 (d,
CP
2JCP = 11.3 Hz, o-Ph), 130.9 (d, 4JCP = 1.3 Hz, p-Ph), 133.2 (d, 3JCP
=
3
2
9.8 Hz, m-Ph), 134.8 (d, JCP = 77.6 Hz, ipso-Ph) ppm. 31P NMR
(121.5 MHz, C6D6): δ 20.4 ppm. 31P NMR (121.5 MHz, Tol): δ 21.2
ppm. IR: 3053 (w), 2906 (m), 2856 (s) 1435 (s), 1299 (s), 1103, (s),
900 (s), 810 (s), 803 (s), 746 (s), 692 (s), 585 (s), 481 (s) cm−1.
X-ray Crystallographic Studies. Crystal data were collected with
a Stoe-IPDSII area-detector diffractometer using graphite-monochro-
mated Mo Kα radiation (λ = 71.073 pm) at 100 K. The detector was
placed at a distance of 1.2 cm from the crystal. Data reduction was
carried out by using the IPDS software X-Area (Stoe).29 The data were
empirically corrected for absorption and other effects by using
multiscans.30 The structures were solved by direct methods (Sir-97)31
1
7
7
−5.92 ppm. Li NMR (155.4 MHz, C6D6): δ −6.36 ppm. Li NMR
(155.4 MHz, THF-d8): δ 1.11 ppm. IR: 2910 (bs), 2858 (bs), 1387
(w), 1308 (s), 1018 (w), 938 (m), 899 (m), 765 (s), 692 (m), 464 (s)
cm−1.
[(Li-CH2-PPh2-C5H3tBu)2] (11). 1H NMR (500.1 MHz, C6D6): δ
2
0.05 (d, JHP = 9.0 Hz, 2H, PCH2Li), 1.45 (s, 9H, C5H3tBu), 6.28−
6.32 (m, 2H, C5H3tBu), 6.44−6.43 (m, 1H, C5H3tBu), 7.20−6.94 (m,
1
6H, o-/m,p-Ph), 7.61−7.30 (m, 4H, m-/o-Ph) ppm. H NMR (400.1
2
MHz, THF-d8): δ −0.01 (d, JHP = 12.0 Hz, 2H, PCH2), 1.19 (s, 9H,
2
and refined by full-matrix least-squares techniques against Fo
C5H3tBu), 5.76−5.91 (m, 3H, C5H3tBu), 7.24−7.66 (m, 10H, PPh2)
(SHELXL-97).32 The programs PLATON33 and PLUTON34 were
used to check the results of the X-ray analyses.
ppm. 13C NMR (100.6 MHz, C6D6): δ −4.9 (br s, PCH2), 32.0 (s,
1
C(CH3)3), 33.1 (s, C(CH3)3), 96.7 (d, JCP = 115.8 Hz, 1-C5H3tBu),
3
106.8 (br s, 2-C5H3tBu), 111.0 (d, JCP = 16.7 Hz, 4-C5H3tBu), 111.0
(d, 2JCP = 9.8 Hz, 5-C5H3tBu), 130.4 (br s, o-Ph), 131.7 (d, 3JCP = 9.5
ASSOCIATED CONTENT
* Supporting Information
Experimental details for compounds 1−4, CIF files giving
crystallographic data for compounds 5a,b, 6, 9, and 11, figures
giving 1H, 31P, 7Li and 13C NMR spectra of the complexes, and
text giving additional experimental details. This material is
available free of charge via the Internet at http://pubs.acs.org.
■
1
Hz, m-Ph), 135.8 (s, p-Ph), 136.0 (d, JCP = 94.2 Hz, ipso-Ph), 138.8
S
(d, 3JCP = 14.4 Hz, 3-C5H3tBu) ppm. 13C NMR (62.5 MHz, THF-d8):
1
δ −2.7 (d, JCP = 38.8 Hz, PCH2), 32.6 (s, C(CH3)3), 33.7 (s,
C(CH3)3), 75.4 (d, 1JCP = 125.5 Hz, 1-C5H3tBu), 107.8 (d, 2JCP = 15.6
Hz, 2-C5H3tBu), 112.6 (d, 3JCP = 18.1 Hz, 4-C5H3tBu), 115.4 (d, 2JCP
15.6 Hz, 5-C5H3tBu), 127.7 (d, 2JCP = 10.6 Hz, o-Ph), 130.4 (d, 1JCP
=
=
85.6 Hz, ipso-Ph), 132.5 (d, 3JCP = 9.4 Hz, m-Ph), 132.6 (d, 4JCP = 2.5
Hz, p-Ph), 140.7 (s, 3-C5H3tBu) ppm. 31P NMR (121.5 MHz,
hexane): δ 21.4 ppm. 31P NMR (161.9 MHz, THF-d8): δ 20.3 ppm.
AUTHOR INFORMATION
■
31P NMR (161.9 MHz, C6D6): δ 23.1 ppm. Li NMR (155.4 MHz,
7
Corresponding Author
pentane): δ −5.98 ppm. 7Li NMR (155.4 MHz, C6D6): δ −5.89 ppm.
7Li NMR (155.4 MHz, THF-d8): δ 0.92 ppm. IR: 2953 (w), 2858 (w),
1435 (m), 1200 (m), 1174 (w), 1088 (m), 1054 (m), 1026 (m), 713
(s), 691 (s), 531 (s) cm−1.
*Tel: +49 (0)6421 2825693. E-mail: jsu@staff.uni-marburg.de.
Present Address
†Institute of Inorganic Chemistry, RWTH Aachen University,
Landoltweg 1, D-52056 Aachen, Germany.
1
[(Li-CH2-PMe2-C5H3tBu)2] (12). H NMR (300.1 MHz, C6D6): δ
2
2
−0.59 (d, JHP = 12.3 Hz, 2H, PCH2), 1.06 (d, JHP = 12.5 Hz, 6H,
PMe2), 1.42 (m, 4H, β-THF), 1.50 (s, 9H, C5H3tBu), 3.57 (m, 4H, α-
THF), 6.15 (m, 1H, 4-C5H3tBu), 6.18 (m, 1H, 2-C5H3tBu), 6.32 (m,
Notes
The authors declare no competing financial interest.
1
1H, 5-C5H3tBu) ppm. H NMR (250.0 MHz, THF-d8): δ −0.59 (d,
ACKNOWLEDGMENTS
We thank Dipl.-Chem. Fabian Schroder, Marburg, Germany,
for his help in the replication of a synthesis and characterization
and Chemetall GmbH, Frankfurt/Main, Germany, for financial
support.
■
2JHP = 10.0 Hz, 2H, PCH2Li), 1.20 (s, 9H, C5H3tBu), 1.42 (d, JHP
=
2
̈
12.5 Hz, 6H, PMe2), 5.70−5.65 (m, 1H, 4-C5H3tBu), 5.70−5.72 (m,
1H, 2-C5H3tBu), 5.82−5.77 (m, 1H, 5-C5H3tBu) ppm. 13C NMR
1
(75.5 MHz, C6D6): δ −4.2 (br s, PCH2Li), 19.7 (d, JCP = 48.6 Hz,
1
PMe), 19.9 (d, JCP = 47.9 Hz, PMe), 25.8 (s, β-THF), 32.2 (s,
C(CH3)3), 33.4 (s, C(CH3)3), 67.8 (s, α-THF), 82.0 (br s, 1-
C5H3tBu), 103.6 (d, 3JCP = 13.9 Hz, 4-C5H3tBu), 106.0 (d, 2JCP = 11.6
REFERENCES
■
Hz, 5-C5H3tBu), 107.9 (d, 2JCP = 14.4 Hz, 2-C5H3tBu), 138.1 (d, 3JCP
=
(1) (a) Wittig, G.; Rieber, M. Liebigs Ann. Chem. 1949, 562, 177−
186. (b) Schmidbaur, H.; Tronich, W. Chem. Ber. 1968, 101, 3556−
13.9 Hz, 3-C5H3tBu) ppm. 13C NMR (62.5 MHz, THF-d8): δ −0.13
1
1
(d, JCP = 39.4 Hz, PCH2), 21.2 (d, JCP = 52.5 Hz, PMe2), 32.4 (s,
3561. (c) Schmidbaur, H.; Fuller, H. J. Chem. Ber. 1974, 107, 3674−
̈
1
C(CH3)3), 33.5 (s, C(CH3)3), 97.1 (d, JCP = 112.5 Hz, 1-C5H3tBu),
3679.
104.8 (d, 2JCP = 14.4 Hz, 2-/5-C5H3tBu), 106.7 (d, 2JCP = 14.4 Hz, 2-/
(2) (a) Schmidbaur, H. Acc. Chem. Res. 1975, 8, 62−70.
(b) Schmidbaur, H. Angew. Chem., Int. Ed. 1983, 22, 907−927.
(c) Kaska, W. C. Coord. Chem. Rev. 1983, 48, 1−58. (d) Steinborn, D.
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3
3
5-C5H3tBu), 109.1 (d, JCP = 13.1 Hz, 4-C5H3tBu), 135.9 (d, JCP
=
13.8 Hz, 3-C5H3tBu) ppm. 31P NMR (161.9 MHz, C6D6): δ 7.0 ppm.
31P NMR (161.9 MHz, THF-d8): δ 6.25 ppm. 7Li NMR (155.4 MHz,
THF-d8): δ −2.39 ppm. IR: 2964 (s), 2941 (s), 1198 (m), 1091 (m),
943 (s), 899 (m), 797 (s), 737 (s), 713 (s), 687 (s), 493 (m), 433 (m)
cm−1.
[(Cu-CH2-PPh2-C5Me4)2] (13). 9 was prepared in situ according to
route B (theoretical yield: 1.40 mmol), dissolved in toluene (10 mL),
and cooled to −78 °C. A suspension of CuCl (139 mg, 1.40 mmol) in
toluene (8 mL) was cooled to −78 °C and added slowly. The reaction
mixture was warmed to ambient temperature over a period of 12 h.
After another 28 h, the suspension was filtered and the residue washed
with toluene (2 × 8 mL). All volatiles were removed from the filtrate
to give a colorless solid that was washed with pentane (4 × 20 mL)
and dried in vacuo. Yield (over 2 steps): 333 mg, 416 μmol, 59%.
1H NMR (300.1 MHz, C6D6): δ 1.46 (d, 2H, 2JHP = 13.9 Hz, CH2),
1.97 (s, 6H, 2,5-CpMe2), 2.18 (s, 6H, 3,4-CpMe2), 6.98−7.03 (m, 6H,
o-,p-Ph), 7.68−7.74 (m, 4H, m-Ph) ppm. 13C NMR (100.6 MHz,
Marler, D. J. Am. Chem. Soc. 1985, 107, 6908−6915. (b) Uson
Laguna, A.; Laguna, M.; Jimenez, J.; Jones, P. G. Angew. Chem. 1991,
́
, R.;
́
103, 190−191. (c) Schmidbaur, H.; Hartmann, C.; Reber, G.; Muller,
̈
G. Angew. Chem. 1987, 99, 1189−1191. (d) Findeis, B.; Contel, M.;
Gade, L. H.; Laguna, M.; Gimeno, M. C.; Scowen, I. J.; McPartlin, M.
́ ́
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1
C6D6): δ 6.0 (d, JCP = 37.7 Hz, CH2), 11.5 (s, 3,4-CpMe2), 13.6 (s,
1
2/3
2,5-CpMe2), 86.5 (d, JCP = 113.0 Hz, 1-Cp), 117.0 (d,
J
= 12.1
CP
4264
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