Mono- and dilithiation of [(η7-C7H 7)Ti(η5-C5Me5)] (Pentamethyltroticene) for the synthesis of troticenyl monophosphanes and [2]troticenophanes with C-P and C-Si Bridges

Article abstract of DOI:10.1021/om300927r

Pentamethyltroticene, [(η⁷-C₇H ₇)Ti(η⁵-C₅Me₅)] (1), can be selectively metalated at the C₇H₇ ring or at both the C₅Me₅ and C₇H₇ rings using pmdta/nBuLi or pmdta/tBuLi mixtures (pmdta = N,N′,N′,N″, N″-pentamethyldiethylenetriamine) in 1/1 and 1/4 ratios, respectively. The mono- and dilithiated species [(η⁷-C₇H ₆Li)Ti(η⁵-C₅Me₅)]·pmdta (2) and [(η⁷-C₇H₆Li)Ti(η⁵- C₅Me₄CH₂Li)]·pmdta (3) were isolated in high yield and characterized by NMR spectroscopy and elemental analysis. Compound 2 was used to synthesize the pentamethyltroticenyl monophosphane [(η⁷-C₇H₆PPh₂) Ti(η⁵-C₅Me₅)] (4) by reaction with Ph ₂PCl, while 3 was treated with RPCl₂ (R = Ph, Mes) or Me₂SiCl₂ to give the carbaphospha- and carbasila[2]troticenophanes [(η⁷-C₇H ₆)Ti(η⁵-C₅Me₄CH₂)]PR (5, R = Ph; 6, R = Mes) and [(η⁷-C₇H ₆)Ti(η⁵-C₅Me₄CH ₂)]SiMe₂ (8). The chiral phosphanes 5 and 6 are the first examples of non-iron metallocenophanes with a phosphorus atom in the bridge. The coordination ability of 4 and 6 toward transition metals was demonstrated by reaction with Mo(CO)₆ and [(tht)AuCl] (tht = tetrahydrothiophene) or Me₂SAuCl and formation of the bimetallic complexes [{η⁷-C₇H₆PPh₂·Mo(CO) ₅}Ti(η⁵-C₅Me₅)] (9), [(η⁷-C₇H₆PPh₂·AuCl) Ti(η⁵-C₅Me₅)] (10), and [(η⁷-C₇H₆)Ti(η⁵-C ₅Me₄CH₂)]PMes·AuCl (11). These compounds were structurally characterized by multinuclear ¹H, ¹³C, ³¹P, and ²⁹Si NMR spectroscopy, UV/vis spectroscopy, electron ionization mass spectrometry (EI-MS), elemental analysis, and single-crystal X-ray diffraction analysis. The molecular structures of 5, 6 and 8 reveal strained sandwich compounds with tilt angles (α) of 18.5(1)° (5), 19.7(7)° (6), and 13.4(2)° (8). Treatment of 2 with ZnCl ₂ afforded the pentamethyltroticenyl zinc chloride [(η⁷-C₇H₆ZnCl)Ti(η⁵-C ₅Me₅)] (12), which was employed in palladium-catalyzed Negishi C-C cross-coupling reactions with phenyl iodide and iodotroticene to afford phenylpentamethyltroticene [(η⁷-C₇H ₆Ph)Ti(η⁵-C₅Me₅)] (13) and the [7-5]bitroticene [(η⁷-C₇H₆)Ti{μ- η⁵:η⁷-(C₅H₄-C ₇H₆)}Ti(η⁵-C₅Me₅)] (14), which bears a bridging sesquifulvalene ligand. The molecular structures of 13 and 14 in the solid state were also determined by single-crystal X-ray diffraction analysis.

Full text of DOI:10.1021/om300927r

Article
pubs.acs.org/Organometallics
7
5
Mono- and Dilithiation of [(η ‑C H )Ti(η ‑C Me )] (Pentamethyltroticene)
7
7
5
5
for the Synthesis of Troticenyl Monophosphanes and
[
2]Troticenophanes with C−P and C−Si Bridges
Alain C. Tagne Kuate, Swagat K. Mohapatra, Constantin G. Daniliuc, Peter G. Jones,
and Matthias Tamm*
Institut fu
Germany
̈
̈
r Anorganische und Analytische Chemie, Technische Universitat Braunschweig, Hagenring 30, 38106 Braunschweig,
*
S Supporting Information
7
5
ABSTRACT: Pentamethyltroticene, [(η -C H )Ti(η -C Me )]
7
7
5
5
(
1), can be selectively metalated at the C H ring or at both the
7 7
C Me5 and C H rings using pmdta/nBuLi or pmdta/tBuLi
5
7
7
mixtures (pmdta = N,N′,N′,N″,N″-pentamethyldiethylenetriamine)
in 1/1 and 1/4 ratios, respectively. The mono- and dilithiated
7
5
7
species [(η -C H Li)Ti(η -C Me )]·pmdta (2) and [(η -C H Li)-
7
6
5
5
7
6
5
Ti(η -C Me CH Li)]·pmdta (3) were isolated in high yield and
characterized by NMR spectroscopy and elemental analysis. Com-
5
4
2
pound 2 was used to synthesize the pentamethyltroticenyl
7
5
monophosphane [(η -C H PPh )Ti(η -C Me )] (4) by reaction
7
6
2
5
5
with Ph PCl, while 3 was treated with RPCl (R = Ph, Mes) or
2
2
Me SiCl to give the carbaphospha- and carbasila[2]troticeno-
2
2
7
5
phanes [(η -C H )Ti(η -C Me CH )]PR (5, R = Ph; 6, R = Mes)
and [(η -C H )Ti(η -C Me CH )]SiMe (8). The chiral phosphanes 5 and 6 are the first examples of non-iron
7
6
5
4
2
7
5
7
6
5
4
2
2
metallocenophanes with a phosphorus atom in the bridge. The coordination ability of 4 and 6 toward transition metals was
demonstrated by reaction with Mo(CO) and [(tht)AuCl] (tht = tetrahydrothiophene) or Me SAuCl and formation of the
6
2
7
5
7
5
7
bimetallic complexes [{η -C H PPh ·Mo(CO) }Ti(η -C Me )] (9), [(η -C H PPh ·AuCl)Ti(η -C Me )] (10), and [(η -
C H )Ti(η -C Me CH )]PMes·AuCl (11). These compounds were structurally characterized by multinuclear H, C, P, and
Si NMR spectroscopy, UV/vis spectroscopy, electron ionization mass spectrometry (EI−MS), elemental analysis, and single-
crystal X-ray diffraction analysis. The molecular structures of 5, 6 and 8 reveal strained sandwich compounds with tilt angles (α)
7
6
2
5
5
5
7
6
2
5
5
5
1
13
31
7
6
5
4
2
29
of 18.5(1)° (5), 19.7(7)° (6), and 13.4(2)° (8). Treatment of 2 with ZnCl afforded the pentamethyltroticenyl zinc chloride
2
7
5
[
(η -C H ZnCl)Ti(η -C Me )] (12), which was employed in palladium-catalyzed Negishi C−C cross-coupling reactions with
7
6
5
5
7 5
phenyl iodide and iodotroticene to afford phenylpentamethyltroticene [(η -C H Ph)Ti(η -C Me )] (13) and the [7−5]bitroticene
7
6
5
5
7
5
7
5
[
(η -C H )Ti{μ-η :η -(C H -C H )}Ti(η -C Me )] (14), which bears a bridging sesquifulvalene ligand. The molecular structures
7 6 5 4 7 6 5 5
of 13 and 14 in the solid state were also determined by single-crystal X-ray diffraction analysis.
INTRODUCTION
(tBu PCl) allowed the isolation of the ferrocenyl monophos-
2
■
5
5
5
5
5
phanes [(η -C
5
H
4
PtBu
2
)Fe(η -C
5
Me
5
)], [(η -C
5
H
4
PtBu
2
5
)Fe-
Bis(cyclopentadienyl)iron(II), [(η -C H ) Fe] (ferrocene),
continues to be one of the most popular species in organo-
metallic chemistry because of its high stability, unique geometry,
5
5
2
5
5,6
5
(
(
η -C Ph )] (Q-Phos),
and [{η -C H PtBu }Fe{η -C -
5
5
5 4 2 5
7
C H Me) }] (Figure 1, I). The Q-Phos ligand, which is
6
4
5
1
indefinitely stable toward moisture even in solution, is a useful
ligand for palladium-catalyzed cross-coupling reactions such as
aryl halide aminations/etherifications, Suzuki coupling of aryl
and alkylboronic acids, and Heck arylation of olefins at room
and convenient redox properties. The facile functionalization of
one or both C H (Cp) rings has given access to a wide variety of
5
5
ferrocene derivatives, which have found applications in homo-
2
,3
geneous catalysis and material science. Over the years, the
ferrocene skeleton has been modified by replacement of the
hydrogen atoms at the C H rings by alkyl or aryl groups with
the aim of providing sterically more hindered ligands. Repre-
sentative examples of such derivatizations of ferrocene are the
5
−10
temperature.
Furthermore, simultaneous lithiation of both
the C H ring and of one methyl group of the C Me (Cp*)
5
5
5
5
5
5
ring in pentamethylferrocene was successfully achieved, and the
5
5
resulting dilithiated species [(η -C H Li)Fe(η -C Me CH Li)]·
5
4
5
4
2
11
5
pmdta was used for the preparation of the [2]ferrocenophanes
pentamethyl-, pentaphenyl-, and penta-p-tolylferrocenes, [(η -
5
4
C H )Fe(η -C R )] (R = Me, Ph, C H Me). Phosphane func-
5
5
5
5
6
4
tionalization of the nonsubstituted C H ring through monolithiation
and subsequent reaction with di-tert-butylchlorophosphane
Received: October 3, 2012
Published: December 3, 2012
5
5
©
2012 American Chemical Society
8544
dx.doi.org/10.1021/om300927r | Organometallics 2012, 31, 8544−8555

Organometallics
Article
the troticenyl phosphane IV (R = Ph), the Cht-functionalized
7
5
[
(η -C H PPh )Ti(η -C H )] (Figure 1, VII), had been syn-
7 6 2 5 5
thesized three decades ago by lithiation at the seven-membered
ring using nBuLi in diethyl ether (Et O) followed by reaction
2
18
with chlorodiphenylphosphane (PPh Cl). Very recently, we
2
improved the metalation protocols of troticene and presented
an efficient method for its selective lithiation using a mixture of
7
nBuLi and pmdta. The mono- and dilithiated compounds [(η -
5
7
5
C H )Ti(η -C H Li)]·pmdta and [(η -C H Li)Ti(η -C H Li)]·
7
7
5
4
7
6
5
4
pmdta were isolated as crystalline materials in good yield and
used for the direct synthesis of the troticenyl monophosphane IV
and also for the preparation of stanna[n]troticenophanes and a
24−26
wide range of Cp-functionalized troticenes.
Extending this
protocol to pentamethyltroticene, we report herein its selective
lithiation and the use of the resulting mono- and dilithio inter-
mediates for the synthesis of pentamethyltroticenyl monophos-
phanes and of strained [2]troticenophanes with C−P and C−Si
bridges between the seven- and five-membered rings.
Figure 1. Functionalized sandwich complexes.
5
5
[
(η -C H )Fe(η -C Me CH )]ER (ER = SiCl , SiMe , PR, S,
5 4 5 4 2 x x 2 2
RESULTS AND DISCUSSION
■
GeR , SnR ) with C−E bridges between the five-membered rings
Figure 1, II). Because of their ring-tilted structures, these
compounds are markedly strained and therefore suitable for the
generation of high-molecular-weight polymers by ring-opening
polymerization (ROP) reactions. For example, the carbaphos-
pha- and carbathia[2]ferrocenophanes II (ER = PPh, S) were
easily converted into the corresponding polyferrocenes [{(η -
C H )Fe(η -C Me CH )}PPh] and [{(η -C H )Fe(η -
C Me CH )}S] upon heating at elevated temperature.
In contrast to the rich chemistry described above for steri-
cally demanding ferrocene derivatives, that of mixed cyclo-
heptatrienyl−cyclopentadienyl (Cht-Cp) sandwich complexes
containing substituted C R ligands (R ≠ H) remains largely
unexplored. For the group 4−6 transition metals, efforts have
been limited to the synthesis, structural characterization, and
2
2
12
Preparation and Lithiation of Pentamethyltroticene.
The synthesis of pentamethyltroticene, [(η -C H )Ti(η -C Me )]
1), had been previously reported from [(η -C Me )TiCl ] by
treatment of its THF solution with magnesium in the presence of
(
7
5
7
7
5
5
5
(
5 5 3
cycloheptatriene (C H ) to afford 1 in 68% and 37% yields,
7
8
x
13,14
5
respectively.
In analogy to the one-pot procedure recently
25
5
5
5
developed for troticene, we prepared 1 by the reaction of 2 equiv
5
4
5
4
2
n
5
4
5
1
2a
of Li(η -C Me ) with TiCl (THF) in THF at room temperature
5
5
4
2
5
4
2
n
without the isolation of the intermediate decamethyltitanocene
dichloride. Thus, a catalytic amount of FeCl , an excess of C H ,
and Mg turnings were directly added to the resulting solution,
and after stirring overnight and evaporation, 1 was isolated in 71%
yield as a blue crystalline solid by direct sublimation from the
crude residue (Scheme 1).
3
7
8
5
5
7
5
electrochemical studies of [(η -C H )M(η -C R )] (M = Ti,
7
7
5 5
Scheme 1. Synthesis of Pentamethyltroticene,
R = Me (pentamethyltroticene); M = Zr, R = Me (pentamethyl-
trozircene); M = Zr, R = iPr (pentaisopropyltrozircene); M = Hf,
R = Me (pentamethyltrohafcene); M = V, R = Me (pentamethyl-
trovacene); M = Cr, R = Me (pentamethyltrochrocene); M = Ta,
7
5
[
(η -C H )Ti(η -C Me )] (1)
7 7 5 5
13−17
R = Me) (Figure 1, III).
To the best of our knowledge, no
lithiation and functionalization of any of these complexes has ever
been reported, although such transformations might be of great
interest in view of the applications found for the pentamethylfer-
rocene system (vide supra).
During the past decade, we and other research groups have
been intensively involved in the chemistry of group 4−6
transition metal Cht-Cp sandwich complexes and have reported
the preparation of [n]troticenophanes, [n]trovacenophanes,
and [n]trochrocenophanes (n = 1−3) with boron, silicium,
germanium, or zirconium in the bridge by the reaction of troticene,
trovacene, or trochrocene with a mixture of n-butyllithium (nBuLi)
and N,N,N′,N′-tetramethylethylenediamine (tmeda) and sub-
sequent treatment with the corresponding Cl ER electro-
1
3,14
1
In agreement with previous reports,
the H NMR spec-
trum of 1 in C D showed two singlets at 5.28 and 1.78 ppm
for the hydrogen atoms of the C H and C Me rings. The C
NMR signal at 89.3 ppm can also be assigned to the C H ring,
whereas the C Me moiety gives rise to two signals at 111.8 and
6
6
1
3
7
7
5
5
7
7
5
5
11.7 ppm for the metal-bound and CH carbon atoms, respectively.
3
The UV/vis spectrum of 1 in toluene exhibits a broad absorption
band in the visible region at λmax 676 nm (ε = 34 L mol− cm ),
1
−1
2
x
2
0−23
phile.
We also established a route for the preparation of
which is consistent with the previously reported data (λ 675 nm,
max
7
5
−1
−1
the phosphane-functionalized derivatives [(η -C H )Ti(η -
ε = 32 L mol cm ) and corresponds to a one-electron HOMO−
7
7
14
C H PR ] (R = Ph, iPr; Figure 1, IV) by reduction of the
LUMO excitation. In comparison, the corresponding band
determined for troticene under identical conditions is only slightly
5
4
2
5
half-sandwich complex [(η -C H PR )TiCl ] (R = Ph, iPr)
5
4
2
3
red-shifted to λmax 693 nm (ε = 24 L mol− cm ).
1
−1 27
with magnesium in the presence of cyclohepatriene. The
7
5
heavier congeners [(η -C H )M(η -C H PR ] (M = Zr, Hf;
Our recent success in the selective lithiation of troticene, using
a 1/1 mixture of n-butyllithium (nBuLi) and N,N′,N′,N″,
7
7
5
4
2
R = Ph, iPr; Figure 1, V and VI) were obtained analogously,
24
through reduction of the zirconocene and hafnocene
N″-pentamethyldiethylenetriamine (pmdta) at room temperature,
5
19
dichlorides [(η -C H PR ) MCl ]. The structural isomer of
encouraged us to extend this protocol to the deprotonation of
5
4
2 2
2
8
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Organometallics
Article
the seven-membered ring or of both the C H and the C Me
to afford troticenyl monophosphanes from 2/R PCl and
7
7
5
5
2
rings in complex 1. Accordingly, the monolithiated species 2 was
prepared by the reaction of 1 with 1.2 equiv of nBuLi/pmdta
carbaphospha[2]troticenophanes from 3/RPCl . The latter
2
compounds would feature a C−P bridge between the five-
and seven-membered rings, and such ansa complexes are of con-
siderable interest, since analogous strained [2]metallocenophanes,
for instance carbaphospha[2]ferrocenophanes, were shown to
produce high-molecular-weight poly(carbaphosphaferrocene)
(
1/1) in hexane for 7 h at room temperature. After isolation by
filtration and repeated rinsing with hexane, 2 was isolated as a
dark green, pyrophoric powder in 88% yield. Our attempts to
synthesize the dilithiated compound 3 under similar conditions
by the reaction of 1 with 2.5 equiv of an equimolar nBuLi/pmdta
or tBuLi/pmdta mixture (1/1) at room temperature overnight
failed, as only a monolithiation at the C H ring occurred. We
12
when heated at 220−250 °C for several hours. Accordingly,
the reaction between 2 and chlorodiphenylphosphane
7
7
(Ph PCl) in THF/hexane at −78 °C afforded the phosphane
2
then followed the route reported by Wrighton and co-workers
for the synthesis of a carbasila[2]ferrocenophane via the dilithia-
derivative 4 as a green crystalline solid in 49% yield. Similarly,
compound 3 was treated with 1 equiv of dichlorophenylphos-
phane (PhPCl ) and dichloromesitylphosphane (MesPCl ) to
5
5
11
tion of [(η -C H )Fe(η -C Me )], but using in our case tBuLi
5
5
5
5
2
2
instead of nBuLi. Thus, the addition of a slight excess of pmdta to
a stirred hexane solution of 1 followed by treatment with 4
equiv of tBuLi at room temperature overnight afforded the
dilithio reagent 3 as a dark brown pyrophoric powder in 94%
yield (Scheme 2).
give the desired ansa complexes 5 and 6 in 29% and 25% yields,
respectively. Compound 7 was isolated in small quantities as
a byproduct during the purification of 5 by recrystallization
at −30 °C. The formation of 7 might have resulted either from
incomplete 2-fold deprotonation of 1 or from partial repro-
tonation of 3 by traces of water to provide a low concentration
of the monolithiated species 2 for the reaction with 1 equiv of
Scheme 2. Mono- and Dilithiation of Pentamethyltroticene (1)
PhPCl (Scheme 3).
2
Scheme 3. Synthesis of the Pentamethyltroticenyl
Monophosphanes and Carbaphospha- and
Carbasila[2]troticenophanes 4−8
Compounds 2 and 3 are insoluble in pentane and hexane but
dissolve well in toluene, THF, and diethyl ether. They are
highly sensitive toward air and moisture but can be stored in a
glovebox argon atmosphere for several weeks without decom-
1
position. The identity of compound 2 was confirmed by H and
1
3
C NMR spectroscopy and also by elemental analysis. Thus,
1
the H NMR spectrum of 2 in C D displayed three multiplets
6
6
at 6.21, 5.57, and 5.37 ppm for the α-, β-, and γ-C H hydrogen
7
6
atoms, together with a singlet at 2.21 ppm for the CH groups.
3
The 13C NMR spectrum of 2 showed four carbon signals
between δ 88.6 and 107.5 ppm for the C H moiety, with the
7
6
signal of the ipso-carbon atom being observed at δ 88.9. All
attempts to obtain single crystals of 2 suitable for X-ray diffrac-
tion analysis failed, but the elemental analysis of the isolated
7
powder is in very good agreement with the composition [(η -
5
C H Li)Ti(η -C Me )]·pmdta (2), indicating that the material is
7
6
5
5
pure enough for further reactions. The dilithio compound 3
The 31P NMR spectrum of 4 in C D displayed a singlet at
6
6
was also characterized by satisfactory elemental analyses and
13.6 ppm, which is at slightly higher field than that reported for
24
additionally by reaction with an excess of Me SiCl in hexane
its troticene congener VII (δ 18.5 ppm). The corresponding
signals for 5 and 6 (δ 30.6 and 45.0 ppm) were observed at
significantly lower field than those found for the related car-
3
at −78 °C. The oily residue obtained was analyzed by electron
ionization mass spectrometry (EI-MS), and the molecular ion
7
5
+
5
5
[
(η -C H SiMe )Ti(η -C Me CH SiMe )] was detected at m/z 418.2.
baphospha[2]ferrocenophanes [(η -C H )Fe(η -C Me CH )]-
5 4 5 4 2
12
7
6
3
5
4
2
3
Functionalization of Pentamethyltroticene. With the
PR ( 7.5 ppm, R = Ph; δ 3.8 ppm, R = Mes). In agreement
with the formation of a C -symmetric complex, the H NMR
1
lithiated compounds 2 and 3 at hand, we aimed at their phos-
phane functionalization by reaction with mono- and dichloro-
phosphanes of the type R PCl and RPCl , which was expected
s
spectrum of 4 showed one singlet at 1.79 ppm for the C Me
5
5
hydrogen atoms, whereas the signal for the hydrogen atoms
2
2
8
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dx.doi.org/10.1021/om300927r | Organometallics 2012, 31, 8544−8555

Organometallics
Article
of the seven-membered ring is split into two multiplets at
5.58 ppm for the α-hydrogen atoms and into a multiplet at 5.20 ppm
for the β- and γ-CH groups. In contrast, the introduction of a
pyramidal phosphorus atom in the bridging position between
the five- and seven-membered rings in 5 and 6 renders the
1
complexes C -symmetric, which affords four H NMR signals
1
for the two sets of diastereotopic methyl groups and six signals
for the three sets of diastereotopic CH groups. Accordingly, the
diastereotopic hydrogen atoms of the bridging CH moiety give
2
2
1
1
rise to two doublets of doublets at 3.58/3.13 ppm ( J( H− H) =
2
1
31
1
(
3.6 Hz, J( H− P) = 5.3/25.5 Hz) for 5 and at 3.68/3.22 ppm
2
1 1 2 1 31
J( H− H) = 13.6 Hz, J( H− P) = 4.3/25.7 Hz) for 6. The
13
number of signals observed in the C NMR spectra is also in
agreement with the assigned C (4) or C symmetry (5, 6) with
s
1
the ipso-C H signal found as doublets at 94.0 ppm
7
6
1
13
31
1
13
31
(
(
J( C− P) = 6.7 Hz) (4), 92.0 ( J( C− P) = 16.9 Hz)
1 13 31
5), and 96.2 ppm ( J( C− P) = 11.3 Hz) (6). For 5 and 6,
1
3
the C NMR signals for the CH moieties also appeared
2
1
13
31
as doublets at 31.0 and 32.3 ppm with J( C− P) coupling
constants of 23.7 and 22.7 Hz, respectively.
Figure 2. ORTEP diagram of 4 with thermal displacement parameters
drawn at the 50% probability level. Selected bond angles (deg): α =
In a fashion similar to the preparation of 5 and 6, the
corresponding carbasila[2]troticenophane 8 was obtained from
the reaction of the dilithio complex 3 with dichlorodimethylsi-
lane (Me SiCl ) as a blue crystalline solid in 33% yield (Scheme 3).
3
.2(2), δ = 176.3.
2
2
Introduction of a bridging tetrahedral silicon atom renders the
complex C -symmetric, which gave rise to the expected two
s
singlets for the C Me fragment and two multiplets in a 2/4
5
4
1
ratio for the C H fragment in the H NMR spectrum. In
7
6
addition, two singlets at 1.92 ppm (2H) and 0.50 ppm (6H)
were found for the SiCH and Si(CH ) hydrogen atoms,
2
3 2
respectively. Both signals show satellites as a result of coupling
with the 29Si nucleus, affording J( H− Si) = 6.6 and 6.3 Hz.
2
1
29
13
Similarly, the C NMR spectrum displayed the corresponding
SiCH and Si(CH ) carbon signals at 17.2 and 0.3 ppm with
J( C− Si) = 50.3 and 50.2 Hz. The Si NMR spectrum of 8
showed a single signal at 11.0 ppm, which is close to the value
2
3 2
1
13
29
29
12
reported for carbasila[2]ferrocenophane (δ 9.1 ppm).
It was previously demonstrated that the lowest energy band
in the optical absorption spectrum of troticene is shifted to
higher energy (blue-shifted) upon bridging of the Cp and Cht
rings and formation of [1]troticenophanes with distorted-
Figure 3. ORTEP diagram of 7 with thermal displacement parameters
drawn at the 50% probability level. Selected bond lengths (Å) and
angles (deg): P−Cl = 2.0952(10); C1−P−Cl = 103.62(11), α =
5.0(2), δ = 174.5.
20,26
sandwich structures.
Likewise, the UV/vis spectra of 5, 6,
and 8 in toluene exhibit visible bands at 656 nm (ε = 129 L
−
1
−1
−1
−1
mol cm ), 666 nm (ε = 114 L mol cm ), and 655 nm
1
−1
(
ε = 53 L mol− cm ), which are shifted hypsochromically
relative to the λmax value of 676 nm (ε = 34 L mol− cm )
established for pentamethyltroticene (1) (vide supra). Since the
associated one-electron HOMO−LUMO transition is partly
d−d and partially ligand to metal charge transfer (LMCT) in
1
−1
2
8
nature, the greater intensity of the bands measured for the
2]troticenophanes can be explained by relaxation of the
Laporte selection rule as the symmetry is lowered by deviation
from an unstrained sandwich structure. It should be noted
that the opposite UV/vis spectroscopic trend was observed for
carbaphospha[2]ferrocenophanes, which showed bathochromic
shifts for their lowest energy absorption band in comparison
[
23
Figure 4. ORTEP diagram of 5 with thermal displacement parameters
drawn at the 50% probability level. Selected bond lengths (Å) and
angles (deg): P−C13 = 1.8846(15), P−C18 = 1.8303(15), C8−C13 =
12
with pentamethylferrocene.
Suitable crystals for X-ray diffraction analysis were obtained
at −30 °C from saturated solutions of 4 and 6 in hexane, 5 and
1
.508(2); C1−P−C13 = 100.50(7), C8−C13−P = 111.29(10).
7
in toluene and 8 in pentane; compound 6 crystallized as a
2
4,26a,29
hexane hemisolvate (6·1/2C H ). The molecular structures of
troticene and its functionalized derivatives,
the Ti−Cht
6
14
4
−8 are shown in Figures 2−6, and selected bond lengths and
bond lengths in 4−8 are shorter than the Ti−Cp bond lengths.
This trend is expected for this class of sandwich complexes,
angles are given in Table 1. In agreement with the structures of
8
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Figure 5. ORTEP diagram of 6 with thermal displacement parameters
drawn at the 50% probability level. Selected bond lengths (Å) and
angles (deg): P−C13 = 1.8985(15), P−C18 = 1.8556(15), C8−C13 =
1.515(2); C1−P−C13 = 97.17(7), C8−C13−P = 111.99(10).
Figure 6. ORTEP diagram of 8 with thermal displacement parameters
drawn at the 50% probability level. The molecule displays approximate
mirror symmetry (rms deviation 0.12 Å). Selected bond lengths (Å)
and angles (deg): Si−C1 = 1.8753(12), Si−C13 = 1.9123(14), Si−
C18 = 1.8718(14), Si−C19 = 1.8735(15), C8−C13 = 1.5119(18);
C1−Si−C13 = 106.73(5), C8−C13−Si = 113.33(8).
since the metal−carbon interaction is usually stronger with
2
3
the seven-membered than with the five-membered ring.
For the unbridged complexes 4 and 7, an almost coplanar
arrangement of the Cht and Cp rings is observed, as indicated
by interplanar angles (α) of 3.2(2) and 5.0(2)° and by Cp −
ct
Ti−Cht (ct = centroid) angles (δ) of 176.3 and 174.5°,
ct
indicating that substitution at the C H ring has no marked
7
7
impact on the sandwich structure of the parent pentamethyl-
1
3
troticene (1).
In contrast, the troticenyl units in the bridged complexes 5,
, and 8 are significantly distorted, as evidenced by smaller δ
6
angles of 163.5° (5), 162.7° (6), and 167.6° (8) along with
larger dihedral angles α of 18.5(1)° (5), 19.7(7)° (6), and
1
3.4(2)° (8). Naturally, these distortions are less pronounced
20
than for silicon- and germanium-bridged [1]troticenophanes;
in agreement with these structures, however, a significantly
larger deviation from planarity is found for the ipso-carbon
atom of the Cht ring than for that of the Cp ring, with βCht and
βCp ranging from 19.1 to 23.8° and from 3.3 to 5.2°,
respectively, in complexes 5, 6, and 8 (see Table 2 for a
definition of all relevant angles). In comparison with the
5
5
analogous carbaphospha[2]ferrocenophanes [{(η -C H )Fe(η -
5
4
1
2
C Me CH )X}] (X = PPh, PMes, SiMe ), their [2]-
5
4
2
2
troticenophane congeners can be regarded as being slightly
more distorted, which can be ascribed to larger Ti−C distances
in comparison to Fe−C distances. In agreement with the
trend observed for these systems (Table 2), the strain of the
[
2]troticenophanes decreases in the order 6 > 5 > 8 on the
basis of the structural data. It should be noted, however, that a
relatively shallow potential was calculated for the bending of
8
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Table 2. Comparison of Selected Angles in Carbaphospha- and Carbasila[2]troticenophanes and in the Corresponding
a
[
2]Ferrocenophanes
complex
α (deg)
βCp (deg)
βCht (deg)
δ (deg)
γ (deg)
7
5
[
[
[
[
[
[
(η -C H )Ti(η -C Me CH )]PPh (5)
18.5(1)
19.7(7)
13.4(2)
15.0(4)
18.3(2)
11.8(1)
4.4
21.7
163.5
36.4(1)
38.6(1)
−5.4(1)
7
6
5
4
2
7
5
(η -C H )Ti(η -C Me CH )]PMes (6)
5.2
19.1
162.7
7
6
5
4
2
7
5
(η -C H )Ti(η -C Me CH )]SiMe (8)
3.3
23.8
167.6
7
6
5
4
2
2
5
5
12
(η -C H )Fe(η -C Me CH )]PPh
11.1(4)
14.0(3)
7.3(3)
14.7(4)
9.4(3)
17.9(3)
169.6(2)
167.2(1)
170.9(14)
5
4
5
4
2
5
5
12
(η -C H )Fe(η -C Me CH )]PMes
5
4
5
4
2
5
5
12
(η -C H )Fe(η -C Me CH )]SiMe
2
5
4
5
4
2
a
Definitions of the angles: α is the dihedral angle between the Cht and Cp rings; β indicates the angle Cht /Cp −Cipso−E (E = bridging element);
ct
ct
δ denotes the angle Cht −Ti−Cp ; γ is the torsion angle C −E−E−C
.
ct
ct
ipso
ipso
−
1
−1 22
troticene and that an energy penalty of approximately 15 kcal mol
can be estimated for δ ≈ 163°.
its regioisomer [(IV)Mo(CO) ] (2069, 1981, 1934, 1917 cm ).
5
23
(2)
Since the A
CO stretching mode has been used as a qualitative
indicator for comparison of the relative donor abilities of various
1
Preparation of Bimetallic Phosphane Metal Complexes.
Our next goal was the preparation of selected phosphane−
metal complexes using the monophosphanes 4−6, in order to
compare their coordination behavior with that of related troti-
31
phosphanes, it can tentatively be concluded that the phosphane
18
4
is a slightly better donor than its Cp congener VII (R = Ph)
but slightly weaker in comparison with the Cp-functionalized phos-
24
1
8,24
phane ligand IV (R = Ph).
cenyl phosphanes such as VII and IV (R = Ph).
Thus, the
Crystals of 9 suitable for an X-ray crystal structure deter-
mination were obtained by slow evaporation of a THF/hexane
solution at room temperature. The molecular structure of 9 is
shown in Figure 7, and selected bond lengths and angles are
reaction of 4 with Mo(CO) in a boiling toluene/THF mixture
afforded the molybdenum complex [(4)Mo(CO) ] (9) as a green
solid in good yield (81%, Scheme 4). The strong low-field shift of
6
5
Scheme 4. Synthesis of the Molybdenum and Gold
Complexes 9−11
Figure 7. ORTEP diagram of 9 with thermal displacement parameters
drawn at the 50% probability level. Selected bond lengths (Å) and
angles (deg): Mo−P = 2.5721(6), Mo−C34 = 1.985(2), Mo−C =
2
1
.025(3)−2.061(3); P−Mo−C34 = 176.79(6). Mo−C34−O5 =
78.0(2), α = 11.0(1), δ = 169.3.
assembled in Table 1. The Mo atom resides in a slightly dis-
torted octahedral environment, while the Ti atom displays a
pronounced deviation from the almost ideal sandwich structure
of 4 (vide supra) with α and δ angles of 11.0(1) and 169.3°,
respectively. The Mo−P bond of 2.5721(6) Å is similar to those
established for the analogous phosphane complexes [(VII)Mo-
the 31P NMR signal from 13.6 ppm in 4 to 54.8 ppm in 9
clearly indicated metal−phosphane coordination. The IR spec-
trum of the Cp* complex 9 displayed the expected four CO
18
24
(CO) ] (2.563(2) Å) and [(IV)Mo(CO) ] (2.5423(4) Å),
5
5
further corroborating the slightly stronger donor ability of the
(2)
(1)
absorption bands at 2074 (A ), 2000 (B ), 1947 (A1 ) and
latter Cp-functionalized troticenyl phosphane IV. All Mo−P
1
1
1
30
1
911 cm− (E), which are similar to those recorded for the Cp
distances fall in the range observed for other Mo(CO)
complexes containing related metallophosphane ligands.
5
−1
18
32
analogue [(VII)Mo(CO) ] (2080, 1995, 1940, 1915 cm ) and
5
8
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2
4
As with IV, the monophosphane 4 was additionally employed
in the preparation of gold(I) complexes, since numerous Au(I)
complexes containing analogous ferrocenyl phosphane ligands had
methyl of the mesityl substituents overlapping at 10.2 ppm. For
instance, the signals for the ipso-C H and ipso-C H Me carbon
7
6
6
2
3
1
3
31
atoms are found at 112.4 and 130.9 ppm, whereby the C− P
33,34
1
31
31
been prepared and structurally characterized.
Treatment of
coupling constants of J( C− P) = 42.0 and 48.4 Hz are sig-
nificantly increased relative to the values in the free phosphane 6.
Unfortunately, all attempts to establish an X-ray crystal struc-
ture of 11 have so far proved unsuccessful, despite the availability
of analytically pure crystalline material (according to elemental
analysis).
the phosphane ligand 4 with 1 equiv of [(tht)AuCl] (tht = tetra-
hydrothiophene) in CH Cl at −78 °C gave, after washing with
hexane and drying under vacuum, the Au(I) complex [(4)AuCl]
2
2
(
10) as a green solid in 60% yield (Scheme 4). Coordination to
31
gold affects a pronounced downfield shift of the P NMR signal,
which is observed at 48.0 ppm. Complex 10 was additionally
characterized by X-ray diffraction analysis, whereby suitable single
crystals were obtained by slow evaporation of a solution of the
compound in THF/hexane at room temperature. The molec-
ular structure of 10 is presented in Figure 8, and selected bond
lengths and angles are assembled in Table 1. With α and δ
Negishi Cross-Coupling Reactions with Zincated Pen-
tamethyltroticene. In a recent paper, we reported the use
7
5
of troticenyl zinc chloride [(η -C H )Ti(η -C H ZnCl)] for
7
7
5
4
Negishi C−C cross-coupling reactions; coupling with phenyl
7
5
iodide (PhI) afforded phenyltroticene [(η -C H )Ti(η -C H Ph)],
7
7
5
4
7
5
whereas coupling with iodotroticene, [(η -C H )Ti(η -C H I)],
7
7
5
4
7
gave the bimetallic pentafulvene complex [5−5]bitroticene, [(η -
5
5
7
26
C H )Ti{μ-η :η -C H -C H }Ti(η -C H )]. In a similar fashion,
7
7
5
4
5
4
7
7
the lithio complex 2 was zincated by the reaction of 2 with ZnCl ,
2
7
5
and the resulting complex [(η -C H ZnCl)Ti(η -C Me )] (12)
7
6
5
5
was mixed with PhI and a catalytic amount (5 mol%) of
Pd(dppf)Cl ] (dppf = diphenylphosphinoferrocene) in THF;
[
2
the mixture was heated at 60 °C for 16 h to afford the phenyl-
substituted pentamethyltroticene 13 as a green crystalline solid
in moderate 31% yield (Scheme 5). Likewise, coupling of 12
Scheme 5. Negishi Cross-Coupling Reactions Involving the
Zincated Troticene 12
Figure 8. ORTEP diagram of 10 with thermal displacement
parameters drawn at the 50% probability level. Selected bond lengths
(
Å) and angles (deg): P−Au = 2.2365(8), Au−Cl = 2.2896(8); C1−
P−Au = 114.05(9), P−Au−Cl = 175.80(3), α = 8.8(2), δ = 171.3.
angles of 8.8(2) and 171.3°, the deviation from an ideal sand-
wich structure in 10 is less pronounced than in the Mo(CO)
5
35
complex 9. As expected for Au(I) complexes, 10 displays an
almost linear P−Au−Cl axis (175.80(3)°), and the Au−P and
Au−Cl distances of 2.2365(8) and 2.2896(8) Å are similar to
those found for two crystallographically independent molecules
of [(IV)AuCl] (Au−P = 2.216(3)/2.219(3) Å; Au−Cl =
24
2
.287(3)/3.302(3) Å); the structural parameters are also in
good agreement with those previously determined for gold(I)
chloride complexes containing (diphenylphosphanyl)ferrocene
3
3
ligands.
The reaction of the carbaphospha[2]troticenophane 6 with
[
Au(SMe )Cl] afforded the corresponding Au(I) complex 11
2
as a green solid in 69% yield. Phosphorus coordination is indi-
3
1
cated by a low-field shift of the P NMR signal from 45.0 ppm
in 6 to 61.3 ppm in 11. The presence of a chiral phosphorus
atom again gives rise to four C Me and six individual C H
6
5
4
7
1
7
5
signals in the H NMR spectrum, and the signals for the hydro-
with [(η -C H )Ti(η -C H I)] gave the interannularly bridged
7 7 5 4
7
5
7
gen atoms of the CH bridge appear as a doublet of doublets at
pentamethyl[7−5]bitroticene, [(η -C H )Ti{μ-η :η -(C H −
2
7
7
5
4
1
1
1
2
1
31
5
3
.95 ppm ( J( H− H) = 14.9 Hz, J( H− P) = 1.7 Hz) and as
C H )}Ti(η -C Me )] (14), as a green crystalline solid, albeit
7 6 5 5
a pseudotriplet (arising from overlapping of the two doublets)
in only 21% yield. It should be noted that the latter complex
can be regarded as a new addition to the family of bimetallic
sesquifulvalene complexes, which have received considerable
attention during the last 16 years because of their potential
1
1
1
2
1
31
at 4.29 ppm ( J( H− H) = 14.9 Hz, J( H− P) = 15.2 Hz).
Likewise, the 13C NMR spectrum of 11 exhibits 25 signals for
the 26 carbon atoms, with only the signal assigned to the ortho-
8
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36,37
application as nonlinear optical (NLO) chromophores.
Only
a few examples are known, however, in which the sesquifulvalene
complex is composed of two linked sandwich complexes, with the
5
dicationic iron−ruthenium and ruthenium−ruthenium species [(η -
5
7
5
2+
C H )Fe{μ-η :η -(C H -C H )}Ru(η -C R )] (R = H, Me) and
5
5
5
4
7
6
5 5
5
5
7
5
2+
[
(η -C H )Ru{μ-η :η -(C H -C H )}Ru(η -C H )] representing
5 5 5 4 7 6 5 5
37
the only other examples, to the best of our knowledge.
The H NMR spectrum of 13 exhibits two multiplets each
1
for the C H and C H hydrogen atoms at 5.86 (2H) and 5.28
7
6
6
5
ppm (4H) and at 7.73 (2H) and 7.32 ppm (3H), respectively,
while a singlet at 1.67 ppm is found for the C Me hydro-
5
5
gen atoms. For 14, the corresponding singlet is observed at
.62 ppm together with a singlet at 5.46 ppm for the C H7
1
7
hydrogen atoms. In addition, the bridging sesquifulvalene
ligand gives rise to two pseudotriplets at 5.06 and 5.03 ppm for
the α- and β-C H hydrogen atoms and to a broad multiplet at
5
4
Figure 10. ORTEP diagram of 14 with thermal displacement parameters
drawn at the 50% probability level. Selected bond lengths (Å) and angles
5
.43 ppm for the six hydrogen atoms of the C H moiety. The
C NMR spectra of 13 and 14 are also consistent with the
7 6
1
3
(
deg): C1−C18 = 1.490(2); α = 5.0(1) (at Ti1) and 3.3(1) (at Ti2), δ =
formation of C -symmetric complexes, with the signal for the ipso-
175.9 (at Ti1) and 176.8 (at Ti2).
s
carbon atoms of the Cht and phenyl moieties in 13 appearing at
1
12.3 and 141.8 ppm and those of the Cp and Cht rings in 14 at
selected bond lengths and angles are summarized in Table 1.
97.6 and 90.1 ppm.
Overall, the structural parameters in 13 and 14 are very similar
The UV/vis spectrum (in toluene) of 13 displays a weak
13,29
−1
−1
to those established for troticene and pentamethyltroticene,
band at λmax 670 nm (ε = 61 L mol cm ), very similar to that
recorded for the parent pentamethyltroticene (1) (vide supra).
indicating the presence of unperturbed sandwich moieties. Thus,
α and δ angles of 2.9(1)/177.1° (molecule 1) and 4.7(1)/175.6°
(molecule 2) in 13 and of 5.0(1)/175.9° (at Ti1) and 3.3(1)/
In contrast, a broad band, centered at about λ 713 nm (ε =
max
11 L mol−1 cm ), is found for 14, which represents a
−1
1
1
76.8° (at Ti2) in 14 are found, which closely correspond to
bathochromic shift relative to troticene and pentamethyltroti-
cene (1). Although the extinction coefficient of 111 L mol−1 cm
−1
coplanarity of the Cht and Cp rings. In contrast, the phenyl ring
in 13 and the Cp ring of the troticene moiety in 14 significantly
established for 14 is slightly higher than those found for the
troticene species, this value indicates the absence of a strong
absorption that could be assigned to the charge-transfer (CT)
transition usually associated with sesquifulvalene transition-
metal complexes.
the picture developed for the bonding in group 4 Cht-Cp
complexes, which reveals a strong and appreciably covalent
metal−cycloheptatrienyl interaction, with the cycloheptatrienyl
ring acting more as a −3 ligand than as a +1 ligand. Thereby,
the Cht complex fragment in 14 is not able to act as an
acceptor site, and the two linked troticene moieties can be
regarded as individual, at best weakly interacting, sandwich
complexes.
7
deviate from a coplanar alignment with the Cht ring of the [(η -
5
C H )Ti(η -C Me )] fragment, as indicated by twist angles
7
6
5
5
of 25.4(5)° (molecule 1) and 39.7(6)° (molecule 2) in 13 and
36,37
of 22.2(2)° in 14. A similar twist of 17.93(17)° was found for
This observation is in agreement with
7
5
phenyltroticene [(η -C H )Ti(η -C H Ph)], whereas a perfectly
7
7
5
4
2
3
coplanar arrangement (0°) was observed for the corresponding
[
5−5]bitroticene as a result of its crystallographic inversion
26
symmetry. The C−C intra-ring bond distances in 13 and 14
are 1.497(3)/1.496(3) and 1.490(2) Å, in agreement with the
presence of C(sp )−C(sp ) single bonds. The latter value in 14
lies between the C−C distances established for [5−5]bitroticene
2
2
26
(
1.464(7) Å) and for the 10 independent molecules present in
38
the unit cell of [7−7]bitrovacene (1.50(9)−1.57(12) Å), which
bear Cp−Cp and Cht−Cht linkages, respectively. It is, however,
considerably larger than those established for cationic sesqui-
Crystals of 13 and 14 suitable for X-ray diffraction analysis were
obtained from solutions in hexane (13) or Et O (14) at −30 °C.
1
similar (rms deviation 0.12 Å for all atoms except the phenyl group)
molecules in the asymmetric unit, one of which is displayed in
Figure 9, whereas Figure 10 shows the molecular structure of 14;
2
3 crystallizes with two crystallographically independent but closely
5
5
7
fulvalene complexes of the type [(η -C H )Fe{μ-η :η -(C H -
C H )}ML ] (ML = [Cr(CO) ], [Ru(η -C H )] , [Ru(η -
C Me )] ),
5
5
5
4
+
5
+
5
7
6
n
n
3
5
5
+
36f,37
in which a stronger interaction between the Cp
5
5
and Cht complex fragments is observed.
CONCLUSION
■
The selective lithiation of the sterically hindered pentamethyl-
7
5
troticene [(η -C H )Ti(η -C Me ] (1) has been achieved using
7
7
5
5
the mixture nBuLi/pmdta or tBuLi/pmdta. The mono- and
dilithiated compounds 2 and 3 represent valuable starting materials
to access functionalized derivatives. Thus, 2 and 3 were successfully
used for the synthesis of the pentamethyltroticenyl monophosphane
7
5
[
(η -C H PPh )Ti(η -C Me ] (4) and the [2]troticenophanes 5, 6,
7 6 2 5 5
and 8 with C−P and C−Si bridges between the Cht and Cp
rings. The latter exhibit a high degree of strain, with the
dihedral angle between the planes of the seven- and five-
membered rings being significantly larger than those found in
analogous [2]ferrocenophanes. Furthermore, the donor ability of
Figure 9. ORTEP diagram of 13 (molecule 1) with thermal displacement
parameters drawn at the 50% probability level. Selected bond lengths (Å)
and angles (deg): C1−C18/C1′−C18′ = 1.497(3)/1.496(3); α/α′ =
2.9(1)/4.7(1), δ/δ′ = 177.1/175.6.
8
551
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Article
the phosphane ligands 4 and 6 was demonstrated by the synthesis
of the bimetallic Ti/Mo and Ti/Au complexes 9−11. Finally,
the monolithio species 2 was converted into pentamethyltroti-
δ 111.8 (s, C
5
Me
5
), 89.3 (s, C
7
H
7
), 11.7 (s, C
5
(CH
3
)
5
). UV/vis
−1
−1
(
toluene): λmax (ε) 676 nm (34 L mol cm ).
Synthesis of [(η -C H Li)Ti(η -C Me )]·pmdta (2). A solution of
7
5
7
6
5
5
7
5
n-BuLi/pmdta, prepared from n-butyllithium (1.6 M, 5.5 mmol) and
pmdta (0.96 g, 5.5 mmol) in 12 mL of hexane, was added dropwise to
a suspension of 1 (1.50 g, 5.5 mmol) in hexane (15 mL) at room
temperature. The mixture was then stirred for 5 h, after which time the
color of the suspension had changed from light to dark green. The
solid was isolated by filtration, washed repeatedly with hexane, and
dried under vacuum to yield 2.2 g (88%) of 2 as a green pyrophoric
solid. Anal. Calcd for C H LiN Ti (453.46): C, 68.87; H, 9.78; N,
cenyl zinc chloride [(η -C H ZnCl)Ti(η -C Me ] (12), which
7
6
5
5
can be used as a versatile starting material for palladium-catalyzed
Negishi C−C cross-coupling reactions, as exemplified by
reactions with iodotroticene or phenyl iodide to form the phenyl-
7
5
pentamethyltroticene [(η -C H Ph)Ti(η -C Me ] (13) and the
7
6
5
5
7
5
7
5
[
7−5]bitroticene [(η -C H )Ti{μ-η :η -(C H -C H )}Ti(η -
C Me )] (14), containing a bridging cycloheptatrienyl−cyclo-
7
7
5
4
7
6
26 44
3
5
5
1
9
.27. Found: C 68.59; H, 9.94; N, 10.23. H NMR (400 MHz, C D ,
pentadienyl (sesquifulvalene) ligand. The latter complex repre-
sents the first neutral sesquifulvalene complex and is a rare
example of a system where a sesquifulvalene complex consists of
two bridged sandwich complex fragments. Owing to the viability
of the metalation processes, future investigations will be focused
on the use of pentamethyltroticenyl monophosphanes such as
6 6
2
97 K): δ 6.21 (m, 2H, C H ), 5.57 (m, 2H, C H ), 5.37 (m, 2H,
7
6
7
6
1
3
1
C H ), 2.21 (s, 15H, C Me ), 1.85 (br m, 23H, pmdta). C{ H} NMR
7
6
5
5
(100.68 MHz, C D , 297 K): δ 107.5 (s, C Me ), 100.0 (s, C H ),
6 6 5 5 7 6
8
9.3 (s, C H ), 88.9 (s, i-C H ), 88.6 (s, C H ), 57.1 (s, NCH ), 54.0
7 6 7 6 7 6 2
(bs, NCH ), 45.3 (bs, NCH ), 11.9 (s, C Me ).
2 3 5 5
7
5
Synthesis of [(η -C H Li)Ti(η -C Me CH Li)]·pmdta (3). To a
7
6
5
4
2
7
5
[
[
(η -C H PR )Ti(η -C Me )] and of diphosphanes of the type
stirred solution of 1 (0.52 g, 1.9 mmol) in hexane (12 mL) was added
pmdta (0.40 g, 2.3 mmol), and the mixture was stirred at room tem-
perature for 10 min. After this time, tBuLi (5 mL, 7.7 mmol) was
slowly added through a syringe, and stirring was continued overnight.
The blue solution changed to a dark brown suspension. The solid was
isolated by filtration, washed repeatedly with hexane, and dried under
vacuum to yield 0.83 g (94%) of 3 as a dark brown pyrophoric solid.
Anal. Calcd for C H Li N Ti (459.39): C, 67.98; H, 9.43; N, 9.15.
7
6
2
5
5
7
5
(η -C H PR )Ti(η -C Me CH PR )] in homogeneous transi-
7
6
2
5
4
2
2
tion-metal-catalyzed reactions. Furthermore, the use of the chiral
carbaphospha[2]troticenophanes 5 and 6, after resolution, as
monodentate phosphane ligands in stereoselective catalytic
38
processes can be envisaged.
26
43
2
3
EXPERIMENTAL SECTION
Found: C, 67.79; H, 9.91; N, 10.54.
■
Compound 3 was also characterized by reaction with an excess of
Me SiCl. A solution of Me SiCl (0.020 mL, 0.14 mmol) in hexane
General Procedures. All reactions were performed in a glovebox
under a dry atmosphere of argon (MBraun 200B) or on a high-vacuum
line using Schlenk line techniques. Commercial grade solvents were
purified by a solvent purification system from Mbraun GmbH and
stored over molecular sieves (4 Å) prior to their use. Tetrahydrofuran
was additionally dried over sodium/benzophenone, distilled, degassed,
and stored under argon. NMR spectra were recorded on Bruker DPX
00, DRX 400, and AV 300 devices. Chemicals shifts (δ) are given in
ppm and referenced to tetramethylsilane ( H, C) and 85% H PO4
P). Coupling constants (J) are reported in hertz (Hz), and splitting
patterns are indicated as s (singlet), d (doublet), dd (doublet of
doublets), t (triplet), and m (multiplet). Elemental analyses (C, H, N)
were performed by combustion and gas chromatographic analysis with
an Elementar Vario MICRO elemental analyzer. UV/vis spectra were
recorded on a Shimadzu UV Mini 1240 UV/vis photometer. Electron
ionization mass spectrometry (EI−MS) was performed on a Finnigan
MAT 90 device. IR spectra were recorded on a Bruker Vertex 70
device using the ATR sampling technique.
3
3
(3 mL) was added dropwise to a suspension of 3 (0.029 g, 0.06 mmol)
in hexane (5 mL) at −78 °C. The reaction mixture was slowly warmed
to room temperature, and stirring was continued overnight. The brown
suspension turned into a light green solution. After filtration through a
syringe filter, the solution was evaporated to afford a light green oil,
which was dried under vacuum for four hours. MS (EI, 70 eV): m/z
2
+
4
18.2 (M , 100).
1
13
3
7
5
Synthesis of [(η -C H PPh )Ti(η -C Me )] (4). To a suspension
31
7
6
2
5
5
(
of 2 (0.30 g, 0.7 mmol) in hexane (15 mL), cooled to −78 °C, was
slowly added a solution of chlorodiphenylphosphane (0.14 mL, 0.8
mmol) in THF (10 mL). The mixture was allowed to reach ambient
temperature slowly, and stirring was continued overnight, whereby the
dark green suspension turned into a light green solution. After
filtration over Celite, the solvent was removed under vacuum and the
residue was recrystallized in hexane at −30 °C to afford 0.15 g (51%)
of 4 as a green crystalline solid. Anal. Calcd for C H PTi (458.41):
2
9
31
1
C, 75.98; H, 6.82. Found: C, 75.93; H, 6.86. H NMR (200 MHz,
Materials. ZnCl , C H I, Mo(CO) , n-butyllithium, and tert-
2
6
5
6
C D , 297 K): δ 7.47−7.55 (m, 4H, o-C H ), 7.04−7.10 (m, 6H,
6
6
6
5
butyllithium (1.6 M in hexane) were purchased from Aldrich
and used as received. Prior to use, chlorodiphenylphosphane and
dichlorophenylphosphane (Aldrich) was distilled under high vacuum,
and N,N′,N′,N′,N″-pentamethyldiethylenetriamine (pmdta, Aldrich)
(
m+p)-C H ), 5.58 (m, 2H, C H ), 5.20 (m, 4H, C H ), 1.79 (s, 15H,
6 5 7 6 7 6
13
1
C Me ). C{ H} NMR (100.7 MHz, C D , 297 K): δ 141.4
5
5
6
6
1
13
31
2
13
31
(
d, J( C− P) = 15.1 Hz, i-C H ), 134.9 (d, J( C− P) = 20.6 Hz,
6
5
3 13 31
o-C H ), 128.7 (s, p-C H ), 128.3 (d, J( C− P) = 6.9 Hz,
6
5
6
5
was purified by distillation over CaH . Literature procedures were used
1
13
31
2
m-C H ), 112.5 (s, C Me ), 94.0 (d, J( C− P) = 6.7 Hz, i-C H ),
4
0
41
42
7
6
5
5
5
7
6
to prepare MesPCl , [(tht)AuCl], [(Me S)AuCl], [(η -C H )-
Ti(η -C H I)], [Pd(dppf)Cl ], and Li(η -C Me ).
2 13 31 3 13 31
2
2
7
7
93.1 (d, J( C− P) = 22.7 Hz, α-C H ), 90.3 (d, J( C− P) =
26
43
5
44
7
6
5
31
5
4
2
5
5
7.7 Hz, β-C H ), 90.1 (s, γ-C H ), 11.8 (s, C Me ). P NMR (121.5 MHz,
7 6 7 6 5 5
7
5
Synthesis of [(η -C H )Ti(η -C Me )] (1). To a suspension of
7
7
5
5
C D , 297 K): δ 13.6.
6 6
5
Li(η -C Me ) (3.64 g, 25.6 mmol) in THF (30 mL), cooled at 0 °C,
7
5
7
5
5
Synthesis of [(η -C H )Ti(η -C Me CH )]PPh (5) and [(η -
7 6 5 4 2
5
was added dropwise a solution of [TiCl (THF) ] (4.27 g, 12.8 mmol)
4
2
C H PPhCl)Ti(η -C Me )] (7). A solution of dichlorophenylphos-
7 6 5 5
in THF (40 mL). After complete addition, the mixture was warmed to
ambient temperature and stirring was continued overnight. The yellow
suspension turned to a dark red solution. The latter was added slowly
to a mixture of Mg turnings (1.24 g, 51.2 mmol), cycloheptatriene
phane (0.050 mL, 0.35 mmol) in THF (10 mL) was added dropwise
to a suspension of 3 (0.13 g, 0.3 mmol) in hexane (15 mL) at −78 °C.
The reaction mixture was stirred at this temperature for 2 h and then
slowly warmed to room temperature. After the mixture was stirred
overnight, the solvent was removed under vacuum. Toluene (5 mL)
was added, and the solution was filtered through a syringe filter in a
glovebox to remove LiCl. The filtrate was then concentrated and
stored at −30 °C for several days to give 0.035 g (29%) of 5 as a green
(
2.67 mL, 25.6 mmol), and a catalytic amount of FeCl (5 mol %) in
3
THF (30 mL) at 0 °C. The mixture was then warmed to room tem-
perature and stirred overnight. After all volatiles were removed and the
residue was dried at 70 °C under high vacuum for several hours, the
−2
1
remaining crude product was sublimed at 140 °C and 10 mbar to
give 2.50 g (71%) of pure 1 as a blue crystalline solid. Anal. Calcd
for C H Ti (274.22): C, 74.46; H, 8.09. Found: C, 73.99; H, 8.34.
crystalline solid. H NMR (400 MHz, C D , 297 K): δ 7.69 (m, 2H, o-
6
6
C H ), 7.24 (m, 2H, m-C H ), 7.12 (m, 1H, p-C H ), 6.14 (m, 1H,
6
5
6
5
6
5
17
22
C H ), 5.67 (m, 1H, C H ), 5.52 (m, 3H, C H ), 5.41 (m, 1H, C H ),
7
6
7
6
7
6
7
6
1
2
1
1
2
1
31
H NMR (200 MHz, C D , 297 K): δ 5.28 (s, 7H, C H ), 1.78
3.58 (dd, J( H− H) = 13.6 Hz, J( H− P) = 5.3 Hz, 1H, CH −P),
3.13 (dd, J( H− H) = 13.6 Hz, J( H− P) = 25.5 Hz, 1H, CH −P),
6
6
7
7
2
13
1
2
1
1
2
1
31
(
s, 15H, C (CH ) ). C{ H} NMR (50.3 MHz, C D , 297 K):
5
3
5
6
6
2
8
552
dx.doi.org/10.1021/om300927r | Organometallics 2012, 31, 8544−8555

Organometallics
Article
5
1
31
7
5
2
(
.52 (d, J( H− P) =1.2 Hz, 3H, C Me ), 1.75 (s, 3H, C Me ), 1.59
Synthesis of [{η -C H PPh ·Mo(CO) }Ti(η -C Me )] (9). An equi-
7 6 2 5 5 5
5
4
5
4
1
3
1
s, 3H, C Me ), 1.41 (s, 3H, C Me ). C{ H} NMR (100.7 MHz,
molar mixture of 4 (0.068 g, 0.15 mmol) and Mo(CO) (0.040 g,
5
4
5
4
6
1
13
31
C D , 297 K): δ 146.3 (d, J( C− P) = 17.9 Hz, i-C H ), 129.9 (d,
0.15 mmol) in toluene/THF (3/1, 12 mL) was heated at reflux for 2.5 h.
After it was cooled to room temperature, the green solution was
filtered through a syringe filter. The solvent was then removed and the
residue washed with hexane and dried under vacuum to afford 0.084 g
81%) of 9 as a green solid. Anal. Calcd for C H O PMoTi (694.40):
C, 58.81; H, 4.50, Found: C, 57.82; H, 4.67. H NMR (400 MHz, C D ,
6
6
6
5
2
13
31
3
13
31
J( C− P) = 13.9 Hz, o-C H ), 128.5 (d, J( C− P) = 3.6 Hz,
6
5
4
13
31
m-C H ), 127.0 (d, J( C− P) = 0.7 Hz, p-C H ), 116.5 (d,
6
5
6
5
2
13
31
3
13
31
J( C− P) = 3.4 Hz, C Me ), 114.7 (d, J( C− P) = 1.5 Hz,
5
4
(
C Me ), 114.3 (s, C Me ), 112.9 (s, C Me ), 110.4 (s, C Me ), 105.3 (d,
34 31 5
5
4
5
4
5
4
5
4
1
2
13
31
4
13
31
J( C− P) = 61.9 Hz, α-C H ), 96.4 (s, C H ), 93.8 (d, J( C− P) =
6
6
7
6
7
6
1
13
31
297 K): δ 7.32−7.37 (m, 4H, o-C H ), 6.95−6.97 (m, 6H, (m+p)-
4
(
(
.7 Hz, γ-C H ), 92.2 (d, J( C− P) = 16.9 Hz, i-C H ), 91.7
6
5
7
6
7
6
3
13
31
C H ), 6.10 (m, 2H, C H ), 5.20 (m, 2H, C H ), 5.07 (m, 2H, C H ),
d, J( C− P) = 22.3 Hz, β-C H ), 91.4 (s, C H ), 89.1 (s, C H ), 31.0
6 5 7 6 7 6 7 6
7
6
7
6
7
6
13
1
1
13
31
4
13
31
1.62 (s, 15H, C Me ). C{ H} NMR (100.7 MHz, C D , 297 K):
5 5 6 6
d, J( C− P) = 23.7 Hz, CH −P), 14.3 (d, J( C− P) = 11.2 Hz,
2
2
13
31
3
1
δ 206.7 (d, J( C− P) = 8.6 Hz, cis-CO), the trans-CO resonance
1 13 31
C Me ), 12.2 (s, C Me ), 10.2 (s, C Me ), 10.1 (s, C Me ). P NMR
5
4
5
4
5
4
5
4
was not observed, 139.8 (d, J( C− P) = 34.6 Hz, i-C H ), 133.2 (d,
(
3
81.0 MHz, C D , 297 K): δ 30.6 (s, CH -P). MS (EI, 70 eV): m/z
6
5
6
6
2
2
13
31
4
13
31
+
−1
−1
J( C− P) = 12.3 Hz, o-C H ), 129.7 (d, J( C− P) = 1.5 Hz,
3 13 31
80.1 (M , 100). UV/vis (toluene): λ (ε) 656 nm (129 L mol cm ).
6
5
max
+
HR-MS (EI; m/z): calcd for C H PTi (M ) 380.11700, found 380.11720.
p-C Me
94.6 (d, J( C− P) = 17.9 Hz, α-C H ), 91.2 (d, J( C− P) = 37.7 Hz,
7 6
6
H
5
), 128.0 (d, J( C− P) = 11.7 Hz, m-C
6
H
5
), 113.6 (s, C
5
),
5
23
25
2
13
31
1
13
31
After isolation of green crystals of 5, the filtrate was further stored
at −30 °C to furnish a small quantity of 7 as green crystals suitable for
an X-ray diffraction analysis.
Synthesis of [(η -C H )Ti(η -C Me CH )]PMes (6). A solution of
dichloromesitylphosphane (0.14 g, 0.6 mmol) in Et O (10 mL) was
3
13
31
i-C
(s, C
2074, 2000, 1947, and 1911 cm (ν(CO)). 5
H
), 90.7 (s, γ-C
H
7
), 89.3 (d, J( C− P) = 12.2 Hz, β-C
H ), 11.8
7 6
7
6
Me
6
31
). P NMR (81.02 MHz, C , 297 K): δ 54.8. IR (ATR):
D
6 6
5
5
7
5
−1
7
6
5
4
2
7
Synthesis of [{η -C
tion of (tht)AuCl (0.049 g, 0.15 mmol) in CH
to −78 °C, was slowly added a solution of 4 (0.068 g, 0.15 mmol) in
CH Cl (10 mL), cooled to −30 °C. The mixture was then slowly
H
7
PPh
·AuCl}Ti(η -C
Me
)] (10). To a solu-
(10 mL), cooled
2
2
6
2
5
5
added dropwise to a solution of 3 (0.22 g, 0.5 mmol) in Et O (15 mL)
2
Cl
2
at −78 °C. The reaction mixture was stirred at this temperature for 2 h
and then slowly warmed to room temperature. After it was stirred
overnight, the solution was filtered through Celite and the solvent was
removed under vacuum to afford a brown residue. The residue was
extracted with hexane, and the extract was concentrated and stored
at −30 °C for several days to give 0.058 g (25%) of 6 as a green
2
2
warmed to ambient temperature, and stirring was continued over the
weekend. After filtration through a syringe filter, the solvent was
removed under vacuum to give a green residue. The latter was washed
with hexane and dried under vacuum to afford 0.064 g (60%) of 10 as
1
crystalline solid. H NMR (400 MHz, C D , 297 K): δ 6.58 (d,
a green solid. Anal. Calcd for C219
4.52. Found: C, 50.72; H, 4.83. H NMR (200 MHz, C
δ 7.24−7.33 (m, 4H, o-C H ), 6.80−6.94 (m, 6H, (m+p)-C H ), 5.65
H
31ClPAuTi (690.82): C, 50.42; H,
6
6
4
1
31
4
1
31
J( H− P) = 0.5 Hz, 1H, m-C H Me ), 6.57 (d, J( H− P) = 0.5 Hz,
D
6 6
, 297 K):
6
2
3
1
1
H, m-C H Me ), 5.81 (m, 1H, C H ), 5.35 (m, 4H, C H ), 5.11 (m,
6
5
6
5
6
2
3
7
6
7
6
1
3
1
2
1
1
2
1
31
(
m, 2H, C H ), 5.07 (m, 4H, C H ), 1.77 (s, 15H, C Me ). C{ H}
H, C H ), 3.68 (dd, J( H− H) = 13.6 Hz, J( H− P) = 4.3 Hz, 1H,
7 6 7 6 5 5
7
6
2
13
31
2
1
1
2
1
31
NMR (100.6 MHz, C D , 297 K): δ 134.7 (d, J( C− P) = 14.0 Hz,
CH −P), 3.22 (dd, J( H− H) = 13.6 Hz, J( H− P) = 25.7 Hz, 1H,
6
6
2
1
13
31
5
1
31
o-C H ), 133.0 (d, J( C− P) = 61.0 Hz, i-C H ), 131.3 (d,
CH −P), 2.35 (d, J( H− P) =1.3 Hz, 3H, C Me ), 2.20 (s, 6H, o-
6
5
6
5
2
5
4
4
13
31
3
13
31
J( C− P) = 2.4 Hz, p-C H ), 128.9 (d, J( C− P) = 11.6 Hz,
C H Me ), 1.95 (s, 3H, p-C H Me ), 1.50 (s, 3H, C Me ), 1.38 (s, 3H,
6
5
6
2
3
6
2
3
5
4
1
3
1
2
13
31
C Me ), 1.22 (s, 3H, C Me ). C{ H} NMR (100.7 MHz, C D ,
m-C
H
6
5
), 114.4 (s, C
5
Me
5
), 92.9 (d, J( C− P) = 16.9 Hz, α-C
7
H
6
),
), 84.5 (d,
), 12.3 (s, C Me ). P NMR (81.02
5 5
5
4
5
4
6
6
1
13
31
3
13
31
2
97 K): δ 139.7 (d, J( C− P) = 28.2 Hz, i-C H Me ), 139.4 (d,
90.9 (s, γ-C
7
H
6
), 90.4 (d, J( C− P) = 14.6 Hz, β-C H
7 6
6
2
3
2
13
31
4
13
31
1
13
31
31
J( C− P) = 10.4 Hz, o-C H Me ), 136.3 (d, J( C− P) = 1.1 Hz,
J( C− P) = 74.9 Hz, i-C
MHz, C , 297 K): δ 48.0.
Synthesis of [(η -C
7
H
6
6
13
2
3
3
31
p-C H Me ), 130.4 (d, J( C− P) = 0.7 Hz, m-C H Me ), 115.1 (d,
D
6 6
6
2
3
6
2
3
2
13
31
3
13
31
7
5
J( C− P) = 3.0 Hz, C Me ), 114.2 (d, J( C− P) = 1.8 Hz,
H
7
6
)Ti(η -C
5
Me
4
CH
2
)]PMes·AuCl (11). To a
5
4
solution of (SMe )AuCl (0.021 g, 0.07 mmol) in CH Cl (5 mL),
cooled to −78 °C, was slowly added a solution of 6 (0.030 g, 0.07 mmol)
in CH Cl (5 mL), cooled to −30 °C. The mixture was then warmed to
ambient temperature slowly, and stirring was continued for 2 h. After
filtration through a syringe filter, the solvent was removed under vacuum
to give a green residue. The latter was washed with pentane and dried
under vacuum to afford 0.032 g (69%) of 11 as a green solid. Anal. Calcd
for C H ClPAuTi (654.10): C, 47.69; H, 4.77. Found: C, 47.61; H,
4.94. H NMR (600 MHz, THF-d
C Me ), 114.1 (s, C Me ), 112.6 (s, C Me ), 110.0 (s, C Me ), 102.9
2
2
2
5
4
5
4
5
4
5
4
2
13
31
1
13
31
(
d, J( C− P) = 61.3 Hz, α-C H ), 96.2 (d, J( C− P) = 11.3 Hz,
7
6
4 13 31
i-C H ), 96.0 (s, C H ), 91.5 (d, J( C− P) = 4.1 Hz, γ-C H ), 91.0
2
2
7
6
7
6
7
6
3
13
31
(
3
7
d, J( C− P) = 22.3 Hz, β-C H ), 90.9 (s, C H ), 88.8 (s, C H ),
7
6
7
6
7
6
1 13 31 3 13 31
2.3 (d, J( C− P) = 22.7 Hz, CH −P), 25.5 (d, J( C− P) =
2
4 13 31
.2 Hz, o-C H Me ), 20.7 (s, p-C H Me ), 14.5 (d, J( C− P) =
6
2
3
6
2
3
31
1
2.4 Hz, C Me ), 12.2 (s, C Me ), 10.1 (s, C Me ). P NMR (162.1 MHz,
5 4 5 4 5 4
C D , 297 K): δ 45.0 (s, CH -P). UV/vis (toluene): λ (ε) 666 nm (114
L mol cm ). MS (EI, 70 eV): m/z 422.2 (M , 100). HR-MS (EI; m/z):
calcd for C H PTi (M ) 422.16399, found 422.16367.
Synthesis of [(η -C H )Ti(η -C Me CH )]SiMe (8). To a suspen-
sion of 3 (0.22 g, 0.5 mmol) in hexane (10 mL), cooled to −78 °C,
was slowly added a solution of dichlorodimethylsilane (0.072 mL,
.60 mmol) in hexane (10 mL). The reaction mixture was then slowly
warmed to room temperature and stirred overnight. After filtration
through Celite, all volatiles were removed under high vacuum to leave
a blue-green oily residue. The latter was dissolved in 1 mL of pentane,
and the solution was stored at −30 °C for several days, whereby
.055 g (33%) of 8 deposited as a blue crystalline solid. Anal. Calcd for
C H SiTi (330.13): C, 69.08; H, 7.93. Found: C, 68.84; H, 8.19. H
NMR (400 MHz, C D , 297 K): δ 5.62 (m, 2H, C H ), 5.52 (m, 4H,
C H ), 1.94 (s, 6H, C Me ), 1.92 (s, 2H, CH -Si), 1.55 (s, 6H, C Me ),
.50 (s, J( H− Si) = 6.3 Hz, 3H, C Me ). C{ H} NMR
100.7 MHz, C D , 297 K): δ 117.2 (s, i-C Me ), 111.5 (s, C Me ),
26 31
6
6
2
max
−1
−1
+
1
4
1
31
, 297 K): δ 6.97 (d, J( H− P) =
4 1 31
8
+
0
.7 Hz, 1H, m-C H Me ), 6.83 (d, J( H− P) = 0.5 Hz, 1H,
23
25
6
2
3
7
5
3
1
1
3
1
31
m-C H
6
Me
), 6.27 (dd, J( H− H) = 10.4 Hz, J( H− P) = 16.8 Hz,
3 1 1
7
6
5
4
2
2
2
3
1H, C
H
), 5.88 (t, J( H− H) = 10.3 Hz, 1H, C
H
7
), 5.69 (t,
J( H− H) = 10.3 Hz, 1H, C H ), 5.63 (t, J( H− H) = 10.1 Hz, 1H,
7 6
7
6
6
3
1
1
3
1
1
3
1
1
3
1
1
0
C
7
H
6
), 5.49 (t, J( H− H) = 10.1 Hz, 1H, C H ), 5.29 (t, J( H− H) =
7 6
2 1 31
2
1
1
9.8 Hz, 1H, C
Hz, 1H, CH −P), 3.95 (dd, J( H− H) = 15.0 Hz, J( H− P) = 1.7 Hz,
1H, CH −P), 2.72 (s, 6H, o-C Me ), 2.49 (s, 3H, p-C Me ), 1.98 (s,
3H, C Me ), 1.83 (d, 3H, J( H− P) = 0.3 Hz, 3H, C Me ), 1.69 (s, 3H,
H ), 4.29 (dd, J( H− H) = 15.2 Hz, J( H− P) = 15.2
7 6
2 1 1 2 1 31
2
H
H
2
6
2
3
6
2
3
5
1
31
5
4
5
4
5
1
31
13
1
0
C
5
Me
4
), 1.58 (d, J( H− P) = 0.7 Hz, C
5 4
Me ). C{ H} NMR (150.9
1
2
13
31
MHz, THF-d , 297 K): δ 142.4 (d, J( C− P) = 8.6 Hz, o-C H Me ),
19
26
8
6
2
3
2
13
31
2
13
31
141.0 (d, J( C− P) = 2.4 Hz, p-C H Me ), 140.5 (d, J( C− P) =
6
6
7
6
6
2
3
3 13 31
9.9 Hz, o-C H Me ), 132.1 (d, J( C− P) = 8.1 Hz, m-C H Me ), 131.7
7
6
5
4
2
5
4
6
2
3
6
2
3
2
1
29
13
1
3 13 31 1 13 31
0
(
1
(d, J( C− P) = 8.8 Hz, m-C H Me ), 130.9 (d, J( C− P) = 48.3 Hz,
5
4
6
2
3
3 13 31
i-C H Me ), 116.5 (d, J( C− P) = 4.7 Hz, C Me ), 116.4 (d,
6
6
5
4
5
4
6
2
3
5
4
3 13 31
11.0 (s, C Me ), 96.3 (s, i-C H ), 94.0 (s, C H ), 93.6 (s, C H ), 91.0
J( C− P) = 1.2 Hz, C Me ), 115.1 (s, C Me ), 113.0 (s, C Me ), 111.9
5
4
7
6
7
6
7
6
5
4
5
4
5
4
2 13 31 1 13 31
(
s, C H ), 17.2 (s, CH −Si), 12.9 (s, C Me ), 10.5 (s, C Me ), 0.3 (s,
(d, J( C− P) = 8.5 Hz, i-C Me ), 112.4 (d, J( C− P) = 42.1 Hz, i-
7
6
2
5
4
5
4
5
4
1
13
29
29
2 13 31 3 13 31
J( C− Si) = 50.2 Hz, SiMe ). Si NMR (59.6 MHz, C D , 297K):
C H ), 102.3 (d, J( C− P) = 31.2 Hz, α-C H ), 96.0 (d, J( C− P) =
3
6
6
7
6
7
6
−1
3 13 31
δ 11.0 (s, SiMe ) UV/vis (toluene): λ (ε) 655 nm (53 L mol
12.1 Hz, β-C H ), 93.1 (s, γ-C H ), 92.5 (d, J( C− P) = 20.6 Hz, α-
2
max
7
6
7
6
−1
+
3 13 31
cm ). MS (EI, 70 eV): m/z 330.1 (M , 100). HR-MS (EI; m/z):
calcd for C H SiTi (M ) 330.12797, found 330.12758.
C H ), 91.0 (s, γ-C H ), 89.4 (d, J( C− P) = 11.1 Hz, β-C H ), 36.5
7
6
7
6
7
6
+
1
13
31
4
13
31
(d, J( C− P) = 34.7 Hz, CH −P), 20.8 (d, J( C− P) = 1.1 Hz,
19
26
2
8
553
dx.doi.org/10.1021/om300927r | Organometallics 2012, 31, 8544−8555

Organometallics
Article
4
13
31
C Me ), 16.1 (d, J( C− P) = 1.4 Hz, C Me ), 17.7 (s, C Me ), 12.5 (s,
5
4
5
4
5
4
AUTHOR INFORMATION
3
13
31
■
C Me ), 11.8 (s, p-C H Me ), 10.2 (d, J( C− P) = 5.0 Hz, o-C H Me ).
P NMR (162.1 MHz, THF-d , 297 K): δ 61.3 (s, CH -P).
Synthesis of [(η -C H ZnCl)Ti(η -C Me )] (12). A solution of
5
4
6
2
3
6
2
3
31
Corresponding Author
*E-mail: m.tamm@tu-bs.de. Fax: (+49) 531 391 5387.
8
2
7
5
7
6
5
5
ZnCl (0.17 g, 1.3 mmol) in THF (15 mL) was added dropwise to a
2
Notes
suspension of 2 (0.52 g, 1.1 mmol) in hexane (10 mL) cooled to −78 °C.
The reaction mixture was slowly warmed to room temperature, and
stirring was continued for 2 h. The suspension turned from dark to light
green. The solid was filtered off and washed thoroughly with hexane.
Drying under vacuum afforded 0.29 g (68%) of a light green powder.
This was used for the next reaction without further purification and
characterization.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was partially supported by the Deutsche Forschungsge-
meinschaft through the focus program SPP 1118 ‘‘Secondary
Interactions as a Steering Principle for the Selective Functionaliza-
7
5
Synthesis of [(η -C H Ph)Ti(η -C Me )] (13). A mixture of 12
45
7
6
5
5
tion of Non-Reactive Substrates’’. A.C.T.K. is grateful to the
(
0.84 g, 0.2 mmol), C H I (0.07 g, 0.3 mmol), and Pd(dppf)Cl
6
5
2
Alexander von Humboldt Foundation for a postdoctoral fellowship.
(
1
5 mol%) in 15 mL of THF was heated under vacuum at 60 °C for
6 h. All volatiles were then removed under vacuum, and the residue
was extracted with hexane and filtered through glass wool. Drying
under reduced pressure afforded a green solid. Recrystallization of the
crude product from hexane at −30 °C gave 0.24 g (31%) of pure 13 as
REFERENCES
■
(
1) Special issue: 50th anniversary of the discovery of ferrocene: J.
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1
a green crystalline solid. H NMR (200 MHz, C D , 297 K): δ 7.73
6
6
(
(
4
m, o-C H ), 7.32 (m, (m+p)-C H ), 5.86 (m, 2H, C H ), 5.28 (m,
6 5 6 5 7 6
13
1
H, C H ), 1.67 (s, C Me ). C{ H} NMR (50.3 MHz, C D , 297
7 6 5 5 6 6
K): δ 146.1 (s, i-C H ), 129.1 (s, C H ), 128.8 (s, C H ), 125.7 (s,
6
5
6
5
6
5
C H ), 112.6 (s, C Me ), 112.3 (s, i-C H ), 90.5 (s, C H ), 89.8 (s,
6
5
5
5
7
6
7
6
C H ), 89.6 (s, C H ), 12.1 (s, C Me ). UV/vis (toluene): λ (ε)
7
7
7
6
5
5
max
−
1
−1
+
6
(
70 nm (61 L mol cm ). MS (EI, 70 eV): m/z 350.2 (M ). HR-MS
EI; m/z): calcd for C H Ti (M ) 348.15553, found 348.15460.
(
5) (a) Bildstein, B.; Hradsky, A.; Kopacka, H.; Malleier, R.; Ongania,
+
23 26
K.-H. J. Organomet. Chem. 1997, 540, 127. (b) Aroney, M. J.; Buys, I.
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5
7
5
Synthesis of [(η -C H )Ti{μ-η :η -(C H -C H )}Ti(η -C Me )]
7
7
5
4
7
6
5
5
7
5
(
14). A mixture of 12 (0.21 g, 0.6 mmol), [(η -C H )Ti(η -C H I)]
7 7 5 4
(
0.15 g, 0.5 mmol), and Pd(dppf)Cl (5 mol%) in 15 mL of THF was
2
heated under vacuum at 60 °C for 16 h. The solution became dark
green. All volatiles were removed under vacuum, and the residue was
extracted with diethyl ether. The solution was then concentrated to
2
(
2
(
half its volume and kept at −30 °C overnight. Dark green crystals of
1
1
4 (0.050 g, 21%) were obtained. H NMR (200 MHz, C D , 297 K):
6
6
6944.
3
1
1
δ 5.46 (s, 7H, C H ), 5.43 (br m, 6H, C H ), 5.06 (t, J( H− H) =
7
7
7
6
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3
1
1
5
(
.8 Hz, 2H, C H ), 5.03 (t, J( H− H) = 5.8 Hz, 2H, C H ), 1.62
5
4
5
4
13 1
s, C Me ). C{ H} NMR (50.3 MHz, C D , 297 K): δ 112.7
5
5
6
6
(
s, C Me ), 97.6 (s, i-C H ), 97.2 (s, C H ), 94.3 (s, C H ), 90.1 (s,
5
5
5
4
5
4
5
4
i-C H ), 89.5 (s, C H ), 88.4 (s, C H ), 87.0 (s, C H ), 86.9 (s, C H ),
7
6
7
6
7
7
7
6
7
6
−
1
1
1.9 (s, C Me ). UV/vis (toluene): λ (ε) 713 nm (111 L mol
5 5 max
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−
1
+
cm ). MS (EI, 70 eV): m/z 476.2 (M ). HR-MS (EI; m/z): calcd for
1
05, 181.
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9
́
2
32
2
̈
le, F.; Bartole, A.;
Single-Crystal X-ray Structure Determinations. Single crystals
of each compound were examined and mounted under inert oil. Data
collection was performed on various Oxford Diffraction diffractom-
eters using monochromated Mo Kα or mirror-focused Cu Kα radia-
tion (for details, see the Supporting Information, Table S-1). Absorp-
tion corrections were performed on the basis of multiscans. The data
(
̈
(
2
1
46
were analyzed using the SHELXL97 program system. In all cases, the
non-hydrogen atoms were refined anisotropically. Hydrogen atoms
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directly attached to the seven-membered ring, in some cases with C−
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to rotate but not tip, or were allowed to ride on their attached carbon
atoms. Special features: the hexane molecule of 6 is ordered; structure 7
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(
̈
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ASSOCIATED CONTENT
■
*
S
Supporting Information
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2
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(
·C H , 7−10, 13, and 14, figures giving NMR spectra of 2
6
14
1
13
1
1
13
31
H and C), 3 ( H), 5, 6, and 9 ( H, C, and P), and 13
(
̈
1
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