Synthesis of 1,1′,2-trisubstituted aryl-based ferrocenyl phosphines as precursors for immobilized ligands

Article abstract of DOI:10.1021/om400449v

Ferrocenylaryl or ferrocenylheteroaryl phosphines bearing a carboxaldehyde group, [Fe{1-PPh₂(spacer)-2-NMe₂CH₂C ₅H₃}(C₅H₄CHO)] (spacer = none (rac-12), 1,4-phenylene (rac-13), 1,3-phenylene (rac-14), 2,5-thienylene (rac-15)), were prepared in a facile four-step sequence starting with dibromination of N,N-dimethylaminomethylferrocene (1) followed by Negishi cross-coupling between 1,1′-dibromo-2-N,N-dimethylaminomethylferrocene (rac-2) and aryl or heteroaryl bromide phosphine oxides, Br-spacer-P(O)Ph ₂ (spacer = 1,4-phenylene, 1,3-phenylene, 2,5-thienylene), reduction with trichlorosilane, and functionalization of the 1′-position of the cyclopentadienyl ring. All products were fully characterized by spectroscopy (¹H, ¹³C, and ³¹P NMR, MS, IR) and for rac-3, rac-7 and rac-11 also by X-ray crystallography. Furthermore, preliminary studies on the grafting of rac-12 on silica were conducted.

Full text of DOI:10.1021/om400449v

Article
pubs.acs.org/Organometallics
Synthesis of 1,1′,2-Trisubstituted Aryl-Based Ferrocenyl Phosphines
as Precursors for Immobilized Ligands
Martyna Madalska,† Peter Lonnecke,† Vladimir Ivanovski,‡ and Evamarie Hey-Hawkins*,†
̈
†Faculty of Chemistry and Mineralogy, Universitat Leipzig, Johannisallee 29, 04103 Leipzig, Germany
̈
‡Faculty of Natural Sciences and Mathematics, Institute of Chemistry, Ss. Cyril and Methodius University in Skopje, Arhimedova 5,
1000 Skopje, Republic of Macedonia
S
* Supporting Information
ABSTRACT: Ferrocenylaryl or ferrocenylheteroaryl phos-
phines bearing a carboxaldehyde group, [Fe{1-PPh2(spacer)-
2-NMe2CH2C5H3}(C5H4CHO)] (spacer = none (rac-12), 1,4-
phenylene (rac-13), 1,3-phenylene (rac-14), 2,5-thienylene
(rac-15)), were prepared in a facile four-step sequence starting
with dibromination of N,N-dimethylaminomethylferrocene (1)
followed by Negishi cross-coupling between 1,1′-dibromo-2-
N,N-dimethylaminomethylferrocene (rac-2) and aryl or
heteroaryl bromide phosphine oxides, Br-spacer-P(O)Ph2
(spacer = 1,4-phenylene, 1,3-phenylene, 2,5-thienylene), reduction with trichlorosilane, and functionalization of the 1′-position
of the cyclopentadienyl ring. All products were fully characterized by spectroscopy (1H, 13C, and 31P NMR, MS, IR) and for rac-
3, rac-7 and rac-11 also by X-ray crystallography. Furthermore, preliminary studies on the grafting of rac-12 on silica were
conducted.
A number of unsymmetrically 1,1′-substituted ferrocene
derivatives have been reported and their properties as ligands
studied.6 Their preparation relies on stepwise transmetalation/
functionalization reactions or halogen exchange on suitable
symmetrically 1,1′-substituted precursors.6c These are obtained
in good yield by the reaction of 1,1′-dilithioferrocene-
N,N,N′,N′-tetramethyl-1,2-diaminoethane adduct9 with
nBu3SnCl,10 a bromine source (C2Br2F4 or C2H2Br4),11 or
rarely with iodine.11d An alternative approach involves highly
reactive phosphorus-bridged [1]ferrocenophanes, which under-
go facile ring-opening reactions with organolithium reagents.12
Even though the 1,1′-substitution of N,N-dimethylaminome-
thylferrocene13 or N,N-dimethyl-1-ferrocenylethylamine14 can
proceed in a way similar to that described above, it has hardly
been investigated. The synthesis of (R)-N,N-dimethyl-1-[(S)-
1′,2-bis(halogen)ferrocenyl]ethylamine has been reported in a
patent.15 The stepwise synthesis starts with the preparation of
the dilithio derivative of Ugi’s amine (in the presence of an
amine, e.g., TMEDA), followed by reaction with a halogenating
agent. The products are obtained in reasonable yields, and their
further reaction with 1 equiv of n-butyllithium results in a
monolithioferrocene derivative. Of the two possible lithiation
products, the ortho-substituted compound is favored due to
stabilization via the amino group (ortho effect).16 Reaction with
an electrophile yields a monohalogenated product. The
INTRODUCTION
■
One of the most obvious disadvantages of homogeneous
catalysis is the difficult separation of the catalyst from the
product. This generates costs and sometimes even excludes the
application of catalysts on an industrial scale.1 An attractive
strategy to solve this drawback is the immobilization of the
active metal complexes on insoluble or water-soluble supports
(e.g., SBA-15,2d MCM-41,3 HMS-type SiO2,4 Grace 332,2a
Stober nanoparticles2b). This not only allows facile product
̈
separation and catalyst recycling but also incorporates most of
the advantages of molecular catalysts, such as high activity, mild
reaction conditions, and access to mechanistic studies, into the
immobilized system.5 To immobilize a compound on a solid
support, a suitable substituent (anchoring group) for reaction
with a functional group (linker) of the surface is required.
Depending on the nature of the compounds and their
applications, various linkers and anchoring groups have been
used for immobilization.2
Ferrocene has proved to be a versatile substituent for
phosphanes because of its rich chemistry, stability, and redox
properties and thus plays a significant role as a backbone or
substituent in ancillary ligands.6 Phosphorus-bearing ferrocenes
allow the design of ligands with various electronic and steric
properties in order to increase their efficiency in catalysis.6e,7
Some chiral ferrocenyl bis-phosphines were also immobilized
and their activity was tested: e.g., in the hydroxylation of
benzene2d and ring-closing metathesis,8 Ir-catalyzed imine
hydrogenation,2a Pd-catalyzed hydrogenation of ethyl nicotina-
te,2c and Rh-catalyzed hydrogenation of olefins.2j
Special Issue: Ferrocene - Beauty and Function
Received: May 21, 2013
Published: June 18, 2013
© 2013 American Chemical Society
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remaining halogen atom can then be substituted by addition of
nBuLi and reaction with an electrophile in very good to
excellent yield.
We now report the synthesis of 1,1′,2-trisubstituted aryl-
based ferrocenyl phosphines with different spacers (1,4-
phenylene, 1,3-phenylene, and 2,5-thienylene) between the
ferrocenyl framework and phosphorus atom and a carbox-
aldehyde group at the 1′-position for further immobilization
(Scheme 1).
In the 31P{1H} NMR spectrum of rac-5, two signals were
observed at −24.5 (1-PPh2) and −16.1 ppm (1′-PPh2).
The molecular structure of rac-3 was determined by single-
crystal X-ray crystallography (Figure 1). Room-temperature
(293 K) and low-temperature (130 K) measurements were
performed.
Scheme 1. 1,1′,2-Trisubstituted Aryl-Based Ferrocenyl
Phosphines with a Carboxaldehyde Moiety as Anchoring
Group
RESULTS AND DISCUSSION
■
Figure 1. Molecular structure of rac-3 (at 293 K) with thermal
ellipsoids at the 50% probability level. Hydrogen atoms are omitted for
clarity.
Dilithiation of N,N-dimethylaminomethylferrocene (1) with
nBuLi in the presence of N,N,N′,N′-tetramethylethylenedi-
amine (TMEDA) at the 2- and 1′-positions and further reaction
with C2H2Br4 leads to 1,1′-dibromo-2-N,N-dimethylaminome-
thylferrocene (rac-2), which is an excellent starting material for
the selective, consecutive substitution of both bromine atoms
with various electrophiles and thus for the synthesis of 1,1′,2-
trisubstituted unsymmetrical compounds.
Twinning of the crystal was observed at low temperature as a
result of a so-called translationengleiche phase transition from
the monoclinic space group (P21/c at room temperature) to the
triclinic space group (P1 at low temperature). The phase
̅
transition temperature was not determined. The structural
differences between the two phases are very small and are not
described here in detail. The densities of the two phases of rac-
3 clearly indicate a closer-packed structure for the low-
temperature phase; the NMe2 substituent was no longer
disordered in the low-temperature phase. Selected bond lengths
and bond angles (measurement at 293 K) are presented in
Table 1.
Since previously described 1,2-disubstituted aryl-based
ferrocene derivatives17 were obtained only in moderate yields,
preliminary studies on the corresponding 1,1′,2-trisubstituted
compounds focused on the synthesis of 1-diphenylphosphino-
1′-bromo-2-N,N-dimethylaminomethylferrocene (rac-3). Due
to the formation of a nitrogen−lithium donor bond, lithiation
of rac-2 is preferred at the 2-position, and thus the following
reaction with chlorodiphenylphosphine leads to formation of
rac-3 in 65% yield (Scheme 2).
Table 1. Selected Bond Lengths (pm) and Bond Angles
Despite many attempts to improve the selectivity of the
reaction, the side products 1-bromo-1′-(diphenylphosphino)-2-
N,N-dimethylaminomethylferrocene (rac-4) and 1,1′-bis-
(diphenylphosphino)-2-N,N-dimethyl-aminomethylferrocene
(rac-5) were also always formed (in ca. 28 and 3% yields,
respectively) and could be separated from the product by
column chromatography.
a
(deg) in rac-3
Bond Lengths
P1−C1
P1−C14
181.4(5)
183.9(5)
P1−C20
Br1−C6
184.6(5)
187.4(6)
Bond Angles
1
C1−P1−C14
C1−P1−C20
102.2(2)
102.4(2)
C14−P1−C20
101.2(2)
The structures of compounds rac-3−5 were verified by H
and 31P{1H} NMR spectroscopy. The chemical shift in the
31P{1H} NMR spectrum of rac-4 (δ −17.6 ppm) was in
agreement with the chemical shift for similar compounds, e.g.,
1-diphenylphosphino-1′-N,N-dimethylaminomethylferrocene.18
a
Measurement at 293 K.
Scheme 2. Products Obtained in the Reaction of 1,1′-Dibromo-2-N,N-dimethylaminomethylferrocene (rac-2) with
Chlorodiphenylphosphine
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Scheme 3. Synthesis of 1,1′,2-Trisubstituted Ferrocenyl Phosphine Oxides by Negishi Cross-Coupling Reaction
Scheme 4. Four Types of Products Obtained in the Negishi Cross-Coupling of 1,1′-Dibromo-2-N,N-
a
dimethylaminomethylferrocene (rac-2) with Aryl and Heteroaryl Bromide Phosphine Oxides
a
spacer = 1,4-phenylene, 1,3-phenylene, 2,5-thienylene.
The same selective bromine substitution sequence as
described for the synthesis of rac-3 was used for the synthesis
of trisubstituted ferrocene derivatives with a 1,4-phenylene, 1,3-
phenylene, or 2,5-thienylene spacer. Here, Negishi cross-
coupling19 with the respective aryl or heteroaryl bromide
phosphine oxides (Br-spacer-P(O)Ph2; spacer = 1,4-phenylene,
1,3-phenylene, 2,5-thienylene), which were prepared according
to known procedures,20 was applied (Scheme 3).
Compound rac-7 crystallizes in the triclinic space group P1
̅
with two molecules in the unit cell (Figure 2). Selected bond
lengths and bond angles are summarized in Table 2.
The formation of the main products, 1-diphenylphosphine
oxide(spacer)-1′-bromo-2-N,N-dimethylaminomethylferrocene
(A; spacer = 1,4-phenylene (rac-6), 1,3-phenylene (rac-7), 2,5-
thienylene (rac-8)), is always accompanied by three other
compounds, B−D (Scheme 4). A−D were separated by
column chromatography, and their structures could be
1
determined by H and 31P{1H} NMR spectroscopy and mass
spectrometry.
The chemical shifts in the 31P{1H} NMR spectra of products
of type A and B are similar and do not indicate whether the
coupling reaction took place at the 2- or 1′-position. However,
an analysis of the chemical shifts of the diastereotopic
methylene protons (CH2N) in the 1H NMR spectrum allowed
assignment of the structure to type A or B. For the compound
rac-2, the diastereotopic protons have chemical shifts of 3.36
and 3.43 ppm. Similar distances between both doublets of the
Figure 2. Molecular structure of rac-7 with thermal ellipsoids at the
50% probability level. Hydrogen atoms (other than H15) are omitted
for clarity.
1
methylene protons were observed in the H NMR spectra of
compounds of type B, while compounds of type A showed
these signals at 3.09 and 3.62 ppm. Furthermore, a single-
crystal structure determination confirmed the structure of one
product of type A (rac-7). In addition, the formation of
trisubstituted ferrocene derivatives was proved by mass
spectrometry. Formation of the 1,2-disubstituted products C
and D in the syntheses of rac-6−8 indicates that the
monobrominated ferrocene derivatives were created in one of
the synthesis steps. A characteristic singlet for the unsubstituted
The dihedral angle between the plane of the disubstituted
cyclopentadienyl ring and the plane of the phenylene spacer is
27.2(7)°; turning of the plane of the spacer toward the N,N-
dimethylamino substituent indicates an N1···H15 interaction
(N1···H15 = 236.8 pm; the sum of the van der Waals radii is
264 pm21). The dihedral angle is clearly smaller than those
found for the 1,2-disubstituted counterparts, and this could be
explained by the presence of the bulky bromo substituent at the
1′-position.14
1
cyclopentadienyl ring was observed in the H NMR spectra of
compounds C.
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Table 2. Selected Bond Lengths (pm) and Bond Angles
(deg) of rac-7
Bond Lengths
C2−C14
C16−P1
C20−P1
147.3(2)
180.5(1)
181.3(1)
C26−P1
P1−O1
C6−Br1
181.2(1)
148.9(1)
188.6(1)
Bond Angles
C16−P1−C20
C16−P1−C26
C16−P1−O1
107.9(6)
105.5(6)
112.4(6)
C20−P1−C26
C20−P1−O1
C26−P1−O1
104.9(5)
112.3(6)
113.3(6)
Figure 3. Molecular structure of rac-11 with thermal ellipsoids at the
45% probability level. Hydrogen atoms (other than H3) are omitted
for clarity.
Reduction of compounds rac-6−8 was performed by
employing the same reaction conditions as described for the
synthesis of 1,2-disubstituted ferrocenyl phosphines.17,22 The
31P{1H} NMR spectra of the reaction mixtures after heating to
reflux overnight showed completion of the reaction. The
products rac-9−11 were isolated in very high yields (Scheme
5).
Table 3. Selected Bond Lengths (pm) and Bond Angles
(deg) of rac-11
Bond Lengths
Compound rac-11 crystallizes in the monoclinic space group
P21/c with four molecules in the unit cell (Figure 3). Selected
bond lengths and bond angles are summarized in Table 3.
The tilt angle of 3.4° between the cyclopentadienyl rings in
the trisubstituted ferrocene derivative rac-11 is similar to that of
its 1,2-disubstituted counterpart, (5-diphenylphosphino)-
thienyl-2-N,N-dimethylaminomethylferrocene (2.44°),17 while
the dihedral angle between the plane of the disubstituted
cyclopentadienyl ring and the plane of the thienylene spacer is
smaller in rac-11 (21.9 vs 26.3° in (5-diphenylphosphino)-
thienyl-2-N,N-dimethylaminomethylferrocene17).
For the following immobilization studies, functionalization of
the solid support (silica gel) with commercially available 3-
aminopropyltrimethoxysilane (APTMS) was conducted.23 The
reactive NH2 group undergoes a fast and selective condensation
reaction with carboxaldehydes, yielding only water as a side
product.
C2−C14
C17−P1
C18−P1
145.8(3)
180.9(3)
183.8(3)
C24−P1
C6−Br1
184.2(3)
187.2(3)
Bond Angles
C17−P1−C18
C17−P1−C24
99.4(1)
C18−P1−C24
102.4(1)
101.8(1)
was followed by a condensation reaction between the
carboxaldehyde moiety (anchoring group) of rac-12 and the
primary amino group of the linker, yielding a ferrocenyl
phosphine immobilized on silica gel (Scheme 7).
The performed reactions were monitored by DRIFT IR and
1H, 29Si, 31P, and 13C solid-state NMR spectroscopy.23 The
lower intensity of the OH stretching vibration of the silica
surface at 3741 cm−1 shows that these hydroxyl groups are
involved in the formation of chemical bonds with the APTMS
molecules.25
For this purpose, the remaining bromine atom in rac-3 and
rac-9−11 was selectively replaced with a CHO group to give
compounds rac-12−15 in excellent yields (Scheme 6).
Compounds rac-12−15 were purified by column chromatog-
raphy and obtained as red powders. The characteristic signals
for aromatic aldehydes were detected in the low-field region in
The signal in the solid-state 31P NMR spectrum of
immobilized rac-12 (−29.9 ppm) is slightly shifted in
comparison to the signal in the 31P{1H} NMR spectrum of
rac-12 dissolved in CDCl3 (−25.8 ppm). In the 29Si MAS NMR
spectra, three main types of units present on the surface of silica
(difunctional (D), trifunctional (T), and signals of silica gel
(Q)) can be detected. Trifunctional units show resonances at δ
−49 (T1), −56 (T2), and −65 ppm (T3). Signals of the silica
gel appear at δ −92 (Q2), −101 (Q3), and −110 ppm (Q4).26
The presence of the T3 (δ −66.2 ppm) and T2 (δ −58.6 ppm)
units in the 29Si MAS NMR spectrum of a 3-aminopropylsilyl
(APS)-modified SiO2 surface confirmed the incorporation of
1
the H NMR spectrum. Additional characterization included
13C{1H} and 31P{1H} NMR spectroscopy, EI MS, IR
spectroscopy, and elemental analysis.
Initial studies on the immobilization on chemically modified
silica gel were performed with rac-12 as a representative
derivative. This procedure was described in the literature for
other compounds.24 Grafting of APTMS (linker) on dried SiO2
Scheme 5. Synthesis of 1,1′,2-Trisubstituted Ferrocenyl Phosphines
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Scheme 6. Synthesis of Carboxaldehyde-Functionalized Ferrocenyl Phosphines as Precursors for Immobilization Reactions
Scheme 7. Immobilization of a Ferrocenyl Phosphine Derivative on Modified Silica Gel
Figure 4. N2 adsorption−desorption isotherms of APS-modified silica gel (left) and rac-12-modified silica gel (right).
the APS groups via covalent bonds as a part of the silica gel
structure.24 The 13C CP MAS NMR spectra of such modified
silica gels clearly display three signals in the region of aliphatic
carbon atoms (δ 8.4 (SiCH2), 24.3 (CH2), and 43.7 ppm (d,
1JCN = 134.3 Hz, CH2NH2)).27
silica gel after the condensation reaction, no bands previously
+
assigned to δ(NH2) and δasm.(NH3 ) vibrations were present.
Instead, a new band at 1643 cm−1, which was assigned to the
CN stretching vibration, appeared.29
The N2 adsorption−desorption isotherms of both materials,
measured at 77 K, are shown in Figure 4. Each displays a
characteristic type IV isotherm with H1 hysteresis loop
(IUPAC classification), indicating that the mesoporous
structure is present also after functionalization.30 The surface
area calculated by the BET method, as well as the pore volume
(Vp) and average pore diameter (dp), decreased after the
ferrocenyl derivative was anchored at the surface (Figure 5,
Table 4), which means that the molecules are present not only
on the surface but in the pores as well.24b
The progress of the condensation reaction between the
carboxaldehyde groups and the primary amines was followed by
IR spectroscopy.20,23 The absorbance IR spectra of APS-
functionalized silica gel recorded in the range of 1500−1700
cm−1 showed two strong vibration bands at 1598 (δ(NH2))
and 1668 cm−1 (δasm.(NH3 )). The second band appeared due
+
to formation of hydrogen bonds between the NH2 groups of
the linker and the OH groups of the silica gel, resulting in
SiOH···NH2 units.28 In the DRIFT spectra of the APS-modified
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Figure 5. Pore distribution of APS-modified silica gel (left) and rac-12-modified silica gel (right).
EXPERIMENTAL SECTION
Table 4. Structural Parameters of Modified Silica Gels
■
General Considerations. All manipulations were carried out by
standard Schlenk techniques under an atmosphere of dry, high-purity
nitrogen. Toluene, THF, diethyl ether, and dichloromethane were
dried with an MB SPS-800 Solvent Purification System and stored
over activated 4 Å molecular sieves. Et3N was distilled from MgSO4;
TMEDA was heated to reflux with sodium and distilled under a
nitrogen atmosphere. Deuterated solvents for NMR spectroscopy were
dried as follows: CDCl3 was distilled from P2O5 and stored over
activated 4 Å molecular sieves; C6D6 was dried with sodium, filtered,
and stored over potassium mirror.
Vp
sample
BET surface area (m2/g)
(cm3/g)
dp (nm)
APS-modified silica gel
rac-12-modified silica gel
430.75
411.86
0.532
0.462
4.195
4.020
The number of molecules immobilized on the modified silica
gel was determined by elemental analysis and atomic
absorption spectroscopy (Table 5).
The compounds N,N-dimethylaminomethylferrocene (1),13
[PdCl2(PPh3)2],31 (4-bromophenyl)diphenylphosphine oxide,20a (3-
bromophenyl)diphenylphosphine oxide,20b and (5-bromo-2-thienyl)-
diphenylphosphine oxide20c were synthesized according to literature
procedures. All other chemicals were obtained from commercial
sources and used as supplied.
Spectra were recorded on a Bruker AVANCE DRX 400 NMR
spectrometer at 400.13 (1H NMR), 161.98 (31P NMR), or 100.61
MHz (13C NMR). TMS was used as an internal standard for 1H NMR
spectra, and spectra of other nuclei were referenced to TMS on the δ
scale.32 The signals in the 13C NMR spectra were assigned by 13C{31P}
NMR experiments. EI mass spectra were recorded on a ZAB-HSQ-
VG12-520 Analytical Manchester spectrometer or a MASPEC II
spectrometer; ESI mass spectra were recorded on a Bruker-Daltonics
FT-ICR-MS APEX II spectrometer (m/z values are given for 79Br in
cases where there is a single bromine atom). FTIR spectra were
recorded on a Perkin-Elmer Spectrum 2000 spectrometer. C, H, N
analyses were performed with a Heraeus VARIO EL Analyzer; air-
sensitive samples were prepared for analysis in a glovebox. Melting
points were determined in sealed glass capillaries under nitrogen and
are uncorrected.
1,1′-Dibromo-2-N,N-dimethylaminomethylferrocene (rac-2).
A 68.2 mL portion (1.66 M, 1.1 equiv, 0.11 mol) of nBuLi in n-hexane
was added dropwise at −78 °C to a solution of 25 g (0.10 mol) of
N,N-dimethylaminomethylferrocene (1) in 250 mL of diethyl ether.
The mixture was stirred at room temperature overnight and then
cooled to −78 °C, and 16.6 mL (1.1 equiv, 0.11 mol) of TMEDA was
added slowly. After the mixture was stirred in a liquid nitrogen/
propan-2-ol bath for 1 h, 68.2 mL (1.66 M, 1.1 equiv, 0.11 mol) of
nBuLi in n-hexane was added dropwise and the reaction mixture was
stirred at room temperature overnight.
The dark red reaction mixture was then cooled to −78 °C, and a
diethyl ether solution (ca. 50 mL) of 1,1,2,2-tetrabromoethane (24.5
mL, 0.21 mol, 2.1 equiv) was added dropwise over 6 h in such a
manner that the temperature of the mixture did not exceed −70 °C.
After complete addition, the brown, cloudy reaction mixture was
stirred at room temperature overnight. A 100 mL portion of water was
Table 5. Elemental Analysis and Atomic Absorption
Spectroscopy (AAS) of APS- and rac-12-Modified Silica Gel
NH2 loading
(mmol/g)
Fe
a
sample
C, % H, % N, %
(mmol/g)
APS-modified
silica gel
5.48
1.54
1.52
1.09
rac-12-modified
silica gel
8.41
1.88
1.69
1.21
a
Value obtained by AAS.
The amount of iron and thus the number of immobilized
ferrocenyl phosphine molecules was determined by atomic
absorption spectroscopy. In case of rac-12-modified silica gel,
the amount of iron in the sample is higher than the number of
NH2 groups available for the condensation reaction. Despite
many attempts to remove the unconverted ferrocene derivative
from the silica gel pores, about 10% of rac-12, which is not
chemically bonded but is absorbed on the silica gel, was
retained in the sample.
CONCLUSION
■
Aryl- or heteroaryl-based 1,1′,2-trisubstituted ferrocene deriv-
atives rac-12−15, which have a carboxaldehyde anchoring
group, were synthesized and characterized. The synthetic
approach developed here should also be applicable for other
derivatives as well as for diastereomerically pure ligands starting
from Ugi’s amine, (S)- or (R)-[Fe(NMe2CHMeC5H3)-
(C5H5)].14 Moreover, preliminary studies showed that these
1,1′,2-trisubstituted ferrocene derivatives can be grafted onto
silica gel to prepare immobilized ligands for future catalytic
applications.
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added, and the mixture was extracted with 50 mL of ethyl acetate. The
organic phases were collected, dried with MgSO4, and concentrated by
using a rotary evaporator. The dark brown crude product was purified
by column chromatography (silica gel, eluent acetone/NEt3 (1000/1))
Hz), 3.95 (d, 2H, 3JHH = 7.0 Hz), 4.19 (s br, 1H), 4.22 (s br, 1H), 4.34
(s br, 1H), 4.37 (s br, 1H), 4.56 (s br, 1H), 7.50−7.46 (m, 4H), 7.62−
7.54 (m, 4H), 7.74−7.69 (m, 4H), 7.89−7.87 ppm (m, 2H). 31P{1H}
NMR (CDCl3, 161 MHz): δ 29.1 ppm. 13C{1H} NMR (C6D6, 100
MHz): δ 44.6 (s), 57.4 (s), 69.8 (s), 70.1 (s), 70.5 (s), 72.0 (s), 72.1
(s), 73.6 (s), 75.7 (s), 78.4 (s), 83.3 (s), 87.6 (s), 128.2 (d, 2JCP = 12.1
Hz), 129.1 (d, 2JCP = 11.8 Hz), 131.2 (s), 131.7 and 131.7 (d, JCP not
1
to give rac-2 as a brown oil in 62% yield. H NMR (CDCl3, 400
MHz): δ 2.22 (s, 6H), 3.36 (d, 1H, 2JHH = 12.8 Hz), 3.43 (d, 1H, 2JHH
= 12.8 Hz), 4.07 (s, 2H), 4.17 (s, 1H), 4.22 (s, 1H), 4.29 (s, 1H), 4.32
(s, 1H), 4.43 ppm (s, 1H). 13C{1H} NMR (CDCl3, 100 MHz): δ 45.1
(s), 56.1 (s), 69.3 (s), 70.3 (s), 70.7 (s), 71.1 (s), 72.7 (s), 72.7 (s),
73.2 (s), 78.7 (s), 81.2 (s), 83.7 ppm (s). EI MS: m/z (relative
intensity, %) 401 (100) [M]+, 357 (87), 184 (48), 141 (98), 115 (65),
58 (58). Anal. Calcd for C13H15Br2FeN: C, 39.04; H, 3.53; N, 3.50.
Found: C, 39.03; H, 3.75; N, 3.62.
3
determined, overlapping signals), 132.0 (d, JCP = 9.8 Hz), 132.1 (d,
3JCP = 9.6 Hz), 134.3 (d, 1JCP = 102.1 Hz), 134.4 (d, 1JCP = 105.6 Hz),
4
142.3 ppm (d, JCP = 2.2 Hz). EI MS: m/z (relative intensity, %) 597
(36) [M]+, 555 (16), 475 (9), 355 (20), 277 (17), 201 (37), 182 (16),
152 (16), 121 (17), 77 (20), 58 (100), 44 (34). Anal. Calcd for
C31H29BrFeNOP: C, 62.23; H, 4.89; N, 2.34. Found: C, 62.58; H,
5.30; N, 2.45.
1-Diphenylphosphino-1′-bromo-2-N,N-dimethylaminome-
n
thylferrocene (rac-3). A 4.7 mL portion of BuLi in n-hexane (1.66
1-(3-Diphenylphosphine oxide)phenyl-1′-bromo-2-N,N-di-
methylaminomethylferrocene (rac-7). The compound was
obtained by a Negishi coupling reaction starting from 1,1′-dibromo-
2-N,N-dimethylaminomethylferrocene (rac-2) and (3-bromophenyl)-
diphenylphosphine oxide. The same procedure as in the synthesis of
rac-6 was used. The compound rac-7 was obtained as an orange-red
M, 7.86 mmol, 1.05 equiv) was added dropwise at −40 °C to a
solution of 3.0 g (7.48 mmol) of 1,1′-dibromo-2-N,N-dimethylami-
nomethylferrocene (rac-2) in 50 mL of n-hexane. The reaction mixture
was stirred in such a manner that the temperature of the reaction did
not exceed −10 °C. After 4 h, the clear orange solution was cooled to
−40 °C and 1.4 mL of chlorodiphenylphosphine (7.86 mmol) was
added. A yellow suspension was obtained that was stirred overnight at
room temperature. Approximately 20 mL of water was added, and the
reaction mixture was extracted with ethyl acetate (3 × 20 mL). The
organic phases were combined, dried with MgSO4, and concentrated
by using a rotary evaporator. The crude orange product was purified
by column chromatography (silica gel, eluent acetone/NEt3 (1000/1))
to give rac-3 as an orange oil in 65% yield. Crystals suitable for X-ray
1
powder in 29% yield. Mp: 87−89 °C. H NMR (C6D6, 400 MHz): δ
2
2.05 (s, 6H), 2.85 (d, 1H, JHH = 12.9 Hz), 3.53−3.51 (m, 2H), 3.61
2
3
(d, 1H, JHH = 12.7 Hz), 3.96 (m, 1H), 3.99 (t, 1H, JHH = 2.5 Hz),
4.04−4.02 (m, 2H), 4.27 (br, 1H), 7.15−7.02 (m, 7H), 7.72−7.67 (m,
2
1H), 7.93−7.82 (m, 4H), 8.04−8.01 (m, 1H), 8.51 ppm (d, 1H, JHH
= 12.8 Hz). 31P{1H} NMR (C6D6, 161 MHz): δ 25.4 ppm. 13C{1H}
NMR (C6D6, 100 MHz): δ 44.7 (s), 57.3 (s), 69.5 (s), 70.0 (s), 70.2
(s), 71.7 (s), 72.0 (s), 73.0 (s), 75.3 (s), 78.6 (s), 83.5 (s), 88.2 (s),
128.1 (s), 128.3 (d, 2JCP = 12.1 Hz), 130.0 (d, 2JCP = 9.7 Hz), 131.3 (d,
1
diffraction appeared in the oil after a few weeks. Mp: 54−57 °C. H
2
3JCP = 4.7 Hz), 131.3 (s), 132.2 (d, JCP = 9.73 Hz), 132.3 (d, JCP not
3
NMR (CDCl3, 400 MHz): δ 2.02 (s, 6H), 3.47 (d, 1H, JHH = 12.8
Hz), 3.60 (d, 1H, 2JHH = 12.8 Hz), 3.77 (s, 1H), 3.79 (s, 1H), 3.98 (s,
1H), 4.06 (s, 1H), 4.26 (s, 1H), 4.36 (s, 1H), 4.57 (s, 1H), 7.21−7.58
ppm (m, 10H). 31P{1H} NMR (CDCl3, 161 MHz): δ −25.8 ppm.
13C{1H} NMR (CDCl3, 100 MHz): δ 44.9 (s), 56.7 (d, 3JCP = 9.2 Hz),
2
determined, overlapping signals), 133.2 (d, JCP = 10.5 Hz), 134.0 (d,
1JCP = 103.0 Hz), 134.2 and 134.4 (d, 1JCP = 116.1 Hz), 134.2 (d, 1JCP
= 88.2 Hz), 134.3 (d, 1JCP = 88.2 Hz), 138.7 (d, 3JCP = 12.3 Hz) ppm.
EI MS: m/z (relative intensity, %) 597 (32) [M]+, 555 (19), 475 (11),
277 (21), 201 (40), 182 (14), 121 (23), 77 (25), 58 (100), 44 (43).
Anal. Calcd for C31H29BrFeNOP: C, 62.23; H, 4.89; N, 2.34. Found:
C, 62.11; H, 5.04; N, 2.20.
3
68.7 (s), 69.5 (s), 70.9 (s), 72.2 (s), 73.1 (s), 73.3 (d, JCP = 4.5 Hz),
3
1
76.4 (d, JCP = 3.8 Hz), 77.9 (d, JCP = 10.8 Hz), 92.0 (d, JCP not
determined, overlapped signals), 92.1 (d, JCP not determined,
3
overlapping signals), 127.7 (s), 127.8 (d, JCP = 6.2 Hz), 128.2 (d,
1-(5-Diphenylphosphine oxide)thienyl-1′-bromo-2-N,N-di-
methylaminomethylferrocene (rac-8). The compound was
obtained by a Negishi coupling reaction starting from 1,1′-dibromo-
2-N,N-dimethylaminomethylferrocene (rac-2) and (5-bromothienyl)-
2-diphenylphosphine oxide. The same procedure as in the synthesis of
rac-6 was used. The compound rac-8 was obtained as an orange-red
powder in 22% yield. Mp: 67−72 °C. 1H NMR (CDCl3, 400 MHz): δ
3JCP = 8.1 Hz), 129.3 (s), 132.4 (d, JCP = 18.2 Hz), 135.3 (d, JCP
=
2
2
1
1
21.9 Hz), 138.0 (d, JCP = 8.3 Hz), 139.9 ppm (d, JCP = 8.4 Hz). EI
MS: m/z (relative intensity, %) 505 (100) [M]+, 426 (27), 320 (32),
305 (65), 202 (28), 183 (73), 120 (83), 58 (28). Anal. Calcd for
C25H25BrFeNP: C, 59.32; H, 4.98; N, 2.77. Found: C, 59.52; H, 5.04;
N, 2.64.
2
2
2.17 (s, 6H), 3.09 (d, 1H, JHH = 12.8 Hz,), 3.76 (d, 1H, JHH = 12.8
Hz), 3.96 (s br, 1H), 3.98 (s br, 1H), 4.19 (s br, 1H), 4.24 (s br, 1H),
4.33 (m, 2H), 4,58 (s br, 1H), 7.21−7.23 (m, 1H), 7.39−7.38 (m,
1H), 7.50−7.46 (m, 4H), 7.58−7.54 (m, 2H), 7.81−7.74 ppm (m,
4H). 31P{1H} NMR (CDCl3, 161 MHz): δ 21.7 ppm. 13C{1H} NMR
(C6D6, 100 MHz): δ 44.5 (s), 57.2 (s), 69.8 (s), 70.2 (s), 70.5 (s), 72.0
(s), 72.4 (s), 72.7 (s), 75.2 (s), 78.8 (s), 81.0 (s), 84.1 (s), 127.01 (d,
1-(4-Diphenylphosphine oxide)phenyl-1′-bromo-2-N,N-di-
methylaminomethylferrocene (rac-6). The compound was
n
obtained by a Negishi coupling reaction. A 3 mL portion of BuLi
in n-hexane (1.66 M, 4.98 mmol, 1 equiv) was added dropwise at −40
°C to a solution of 2 g (4.98 mmol) of 1,1′-dibromo-2-N,N-
dimethylaminomethylferrocene (rac-2) in 20 mL of THF. The
reaction mixture was stirred for 4 h at temperatures between −40
and −20 °C. In the next step, 0.52 g of dry ZnCl2 (5.23 mmol, 1.05
equiv) was added at 0 °C and the obtained orange suspension was
warmed to room temperature and stirred for 4 h. A 1 equiv portion of
nBuLi solution (1.66 M, 4.98 mmol, 5 mol %) was added to a
suspension of 0.17 g (0.25 mmol, 5 mol %) of [PdCl2(PPh3)2] in
THF. The obtained dark purple solution was added to the suspension
of the ferrocenyl zinc derivative followed by addition of 1.48 g (4.98
mmol, 1 equiv) of (4-bromophenyl)diphenylphosphine oxide in 20
mL of THF. The reaction mixture was heated to reflux for 20 h under
an inert atmosphere. THF was removed under reduced pressure. The
remaining solid was dissolved in CH2Cl2; H2O was added and the
mixture was extracted with CH2Cl2, and then the combined organic
phases were dried with MgSO4 and concentrated by using a rotary
evaporator. The dark brown crude product was further purified by
column chromatography (silica gel, eluent acetone/NEt3 (1000/1)),
giving a brown oil. The brown oil was dissolved in Et2O, the solution
was filtered, and the solvent was evaporated to give rac-6 as an orange
powder in 27% yield. Mp: 140−141 °C. 1H NMR (CDCl3 400 MHz):
δ 2.18 (s, 6H), 3.09 (d, 1H, 2JHH = 12.8 Hz), 3.62 (d, 1H, 2JHH = 12.8
2
4
2JCP = 12.6 Hz), 128.4 (d, JCP = 12.3 Hz), 131.5 (d, JCP = 2.5 Hz),
131.9 (d, 3JCP = 10.0 Hz), 133.4 (d, 1JCP = 110.5 Hz), 133.5 (d, 1JCP
110.5 Hz), 134.5 (d, JCP = 108.4 Hz), 134.5 (d, JCP = 108.4 Hz),
=
1
1
1
3
134.6 (d, JCP = 108.4 Hz), 136.9 (d, JCP = 8.9 Hz), 150.5 ppm (d,
4JCP = 5.2 Hz). EI MS: m/z (relative intensity, %) 603 (14) [M]+, 559
(7), 361 (17), 283 (9), 223 (11), 201 (47), 183 (22), 115 (28), 77
(38), 58 (100), 44 (38). Anal. Calcd for C29H27BrFeNOPS: C, 57.64;
H 4.50; N, 2.32. Found: C, 58.15; H, 4.73; N, 2.32.
1-(4-Diphenylphosphino)phenyl-1′-bromo-2-N,N-dimethyl-
aminomethylferrocene (rac-9). A 2.3 mL portion (1.68 mmol, 20
equiv) of NEt3 and 1.7 mL (1.68 mmol, 20 equiv) of SiHCl3 were
added to a toluene solution of 0.5 g (0.84 mmol) of 1-(4-
diphenylphosphine oxide)phenyl-1′-bromo-2-N,N-dimethylaminome-
thylferrocene (rac-6). The suspension was heated to reflux overnight
under an inert atmosphere. After the mixture was cooled to room
temperature, 10 mL of a 30% NaOH solution in degassed water was
added and the mixture was stirred at 60 °C for 2 h. The two phases
were separated under an inert atmosphere, and the water phase was
extracted twice with dry Et2O. The combined organic phases were
5858
dx.doi.org/10.1021/om400449v | Organometallics 2013, 32, 5852−5861

Organometallics
Article
dried with MgSO4 and filtered, and the solvent was evaporated under
vacuum. The obtained orange waxy material was purified by flash
column chromatography (eluent acetone/NEt3 (1000/1)) to give rac-
9 as an orange solid in 95% yield. Mp: 111−115 °C. 1H NMR (CDCl3
400 MHz): δ 2.17 (s, 6H), 3.15 (d, 1H, 2JHH = 12.7 Hz), 3.65 (d, 1H,
2JHH = 12.8 Hz), 3.97−3.93 (m, 2H), 4.18 (br, 1H), 4.24 (br, 1H),
4.32 (m, 2H), 4.50 (t, 1H, 3JHH = 3.4 Hz), 7.28−7.23 (m, 2H), 7.36−
evaporator. The dark red crude product was purified by column
chromatography (silica gel, eluent acetone/NEt3 (1000/1)) to give
1
rac-12 as a red-brown oil in 87% yield. Mp: 98−100 °C. H NMR
(CDCl3, 400 MHz): δ 1.99 (s, 6H), 3.22 (d, 1H, 2JHH = 13.5 Hz), 3.51
2
(d, 1H, JHH = 13.5 Hz), 4.02 (s br, 1H), 4.29 (s br, 1H), 4.36 (s br,
1H), 4.41 (s br, 1H), 4.46 (s br, 1H), 4.66 (s br, 2H), 7.28−7.21 (m,
5H), 7.46−7.40 (m, 3H), 7.64−7.59 (m, 2H), 9.57 ppm (s, 1H).
31P{1H} NMR (CDCl3, 161 MHz): δ −25.4 ppm. 13C{1H} NMR
2
7.33 (m, 10H), 7.71 ppm (d, 2H, JHH = 7.8 Hz). 31P{1H} NMR
3
(CDCl3, 161 MHz): δ −6.1 ppm. 13C{1H} NMR (C6D6, 100 MHz): δ
44.6 (s), 57.3 (s), 69.6 (s), 69.9 (s), 70.2 (s), 71.9 (s), 72.1 (s), 73.0
(s), 75.2 (s), 78.5 (s), 83.4 (s), 88.5 (s), 128.2 (d, JCP not determined,
overlapping signals), 128.5 (d, JCP not determined, overlapping
(C6D6, 100 MHz): δ 44.7 (s), 57.3 (d, JCP = 8.7 Hz), 70.4 (s), 70.5
(s), 70.8 (s), 72.5 (d, 3JCP = 4.9 Hz), 74.0 (s), 74.2 (d, 3JCP = 3.8 Hz),
1
74.5 (s), 79.2 (d, JCP = 13.5 Hz), 93.0 (d, JCP not determined,
overlapping signals), 93.0 (d, JCP not determined, overlapping signals),
1
3
2
127.6 (s), 128.1 (d, JCP = 8.3 Hz), 129.2 (s), 132.3 (s), 132.3 (s),
signals), 129.5 (d, JCP = 7.1 Hz), 133.7 (s, JCP = 19.1 Hz), 133.9
2
2
2
2
1
135.4 (s), 135.5 (s), 138.1 (d, JCP = 10.1 Hz), 140.4 (d, JCP = 10.0
Hz), 191.6 ppm (s). EI MS: m/z (relative intensity, %) 455 (34) [M]+,
412 (7), 384 (9), 361 (11), 317 (9), 270 (41), 239 (15), 199 (9), 141
(13), 91 (54), 65 (20). Anal. Calcd for C26H26FeNOP: C, 68.59; H,
5.76; N, 3.08. Found: C, 68.76; H, 5.98; N, 3.20.
(d, JCP = 18.9 Hz), 133.9 (d, JCP = 19.6 Hz), 135.4 (d, JCP = 11.7
1
1
Hz), 137.8 (d, JCP = 12.0 Hz), 137.9 (d, JCP = 12.0 Hz), 139.0 ppm
(s). EI MS: m/z (relative intensity, %) 581 (100) [M]+, 537 (31), 503
(11), 459 (7), 381 (24), 290 (9), 259 (8), 183 (29), 152 (13), 58 (50),
44 (24). Anal. Calcd for C31H29BrFeNP: C, 63.94; H, 5.02; N, 2.41.
Found: C, 64.02; H, 5.34; N, 2.80.
1-(4-Diphenylphosphino)phenyl-1′-carboxaldehyde-2-N,N-
dimethylaminomethylferrocene (rac-13). The compound was
synthesized by using the same procedure as for the synthesis of rac-12.
The compound rac-13 was obtained as an orange powder in 84% yield.
1-(3-Diphenylphosphino)phenyl-1′-bromo-2-N,N-dimethyl-
aminomethylferrocene (rac-10). The compound was synthesized
by using the same procedure as for the synthesis of rac-9. The
compound rac-10 was obtained as an orange powder in 94% yield. Mp:
77−80 °C. 1H NMR (CDCl3, 400 MHz): δ 2.08 (s, 6H), 3.14 (d, 1H,
2JHH = 12.9 Hz), 3.43 (d, 1H, 2JHH = 12.9 Hz), 3.71 (d, 1H, 3JHH = 3.2
1
Mp: 116−119 °C. H NMR (C6D6, 400 MHz): δ 2.00 (s, 6H), 2.73
(d, 1H, 2JHH = 12.6 Hz,), 3.49 (d, 1H, 2JHH = 12.6 Hz), 3.91 (m, 2H),
3
3
3.94 (t, 1H, JHH = 2.4 Hz), 4.03 (t, 1H, JHH =1.5 Hz), 4.26 (t, 1H,
3JHH = 1.2 Hz), 4.34 (t, 1H, JHH = 1.1 Hz), 4.42 (t, 1H, JHH = 1.2
Hz), 7.09−7.06 (m, 6H), 7.50−7.44 (m, 6H), 7.81−7.79 (m, 2H),
9.73 ppm (s, 1H). 31P{1H} NMR (C6D6, 161 MHz): δ −5.8 ppm.
13C{1H} NMR (C6D6, 100 MHz): δ 44.5 (s), 57.4 (s), 68.4 (s), 70.8
(s), 71.3 (s), 71.6 (s), 73.5 (s), 75.0 (s), 75.3 (s), 80.5 (s), 83.64 (s),
88.7 (s), 128.5 (d, JCP not determined, overlapped signals), 128.6 (d,
JCP not determined, overlapped signals), 128.6 (s), 128.6 (d, JCP not
3
3
Hz), 3.76 (m, 1H), 4.02 (t, 1H, 3JHH = 2.2 Hz), 4.29 (t, 1H, 3JHH = 2.0
3
Hz), 4.27−4.26 (m, 2H), 4.38 (t, 1H, JHH = 3.6 Hz), 7.29−7.24 (m,
2H), 7.39−7.36 (m, 10H), 7.64−7.57 ppm (m, 2H). 31P{1H} NMR
(CDCl3, 161 MHz): δ −5.4 ppm. 13C{1H} NMR (CDCl3, 100 MHz):
δ 44.7 (s), 56.5 (s), 69.3 (s), 69.9 (s), 70.4 (s), 71.4 (s), 71.8 (s), 72.3
(s), 74.7 (s), 78.2 (s), 83.0 (s), 89.1 (s), 128.2 (d, 3JCP = 8.5 Hz), 128.6
3
2
(d, JCP = 6.9 Hz), 128.8 (s), 129.7 (s), 132.0 (d, JCP = 23.8 Hz),
2
2
1
3
132.0 (d, JCP = 23.8 Hz), 133.8 (d, JCP = 19.4 Hz), 134.7 (d, JCP
=
determined, overlapped signals,), 128.3 (d, JCP = 6.6 Hz), 133.7 (d,
1
1
2JCP = 17.2 Hz), 133.9 (d, JCP = 17.2 Hz), 133.9 (d, JCP = 19.8 Hz),
2
2
15.3 Hz), 136.9 (d, JCP = 10.9 Hz), 137.2 (d, JCP = 11.0 Hz), 137.4
(d, JCP = 11.1 Hz), 138.0 ppm (d, 3JCP = 5.7 Hz). EI MS: m/z (relative
intensity, %) 581 (100) [M]+, 539 (32), 381 (28), 339 (60), 270 (23),
215 (14), 183 (60), 152 (27), 121 (14), 58 (98), 44 (84). Anal. Calcd
for C31H29BrFeNP: C, 63.94; H, 5.02; N, 2.41. Found: C, 63.51; H,
5.20; N, 2.40.
1
1
1
135.9 (d, JCP = 12.3 Hz), 137.7 (d, JCP = 12.5 Hz), 137.3 (d, JCP
=
12.2 Hz), 138.3 (s), 191.8 ppm (s). EI MS: m/z (relative intensity, %)
531 (100) [M]+, 516 (47), 502 (38), 459 (13), 302 (20), 274 (21),
265 (13), 183 (28), 152 (13), 121 (15), 58 (30). Anal. Calcd for
C32H30FeNOP: C, 72.33; H, 5.69; N, 2.64. Found: C, 72.58; H, 5.73;
N, 2.73.
1-(5-Diphenylphosphino)thienyl-1′-bromo-2-N,N-dimethyl-
aminomethylferrocene (rac-11). The compound was synthesized
by using the same procedure as for the synthesis of rac-9. The
compound rac-11 was obtained as an orange powder in 90% yield.
Mp: 47−51 °C. 1H NMR (CDCl3, 400 MHz): δ 2.18 (s, 6H), 3.14 (d,
1-(3-Diphenylphosphino)phenyl-1′-carboxaldehyde-2-N,N-
dimethylaminomethylferrocene (rac-14). The compound was
synthesized by using the same procedure as for the synthesis of rac-12.
The compound rac-14 was obtained as an orange powder in 86% yield.
Mp: 96−101 °C. 1H NMR (C6D6, 400 MHz): δ 1.99 (s, 6H), 2.76 (d,
2
2
1H, JHH = 12.8 Hz), 3.79 (d, 1H, JHH = 12.9 Hz), 3.95−3.93 (m,
2H), 4.16 (m, 1H), 4.21 (m, 1H), 4.30−4.27 (m, 2H), 4.52 (m, 1H),
7.14−7.11 (m, 1H), 7.28 (m, 1H), 7.34−7.33 (m, 6H), 7.43−7.39
ppm (m, 4H). 31P{1H} NMR (CDCl3, 161 MHz): δ −19.5 ppm.
13C{1H} NMR (CDCl3, 100 MHz): δ 44.8 (s), 57.0 (s), 69.6 (s), 70.1
(s), 70.3 (s), 71.7 (s), 72.0 (s), 72.7 (s), 74.8 (s), 78.8 (s), 81.8 (s),
83.1 (s), 126.7 (d, 3JCP = 7.4 Hz), 128.4 (d, 3JCP = 6.9 Hz), 128.8 (s),
2
2
1H, JHH = 12.2 Hz), 3.46 (d, 1H, JHH = 13.0 Hz), 3.85−3.83 (m,
2H), 3.89 (t, 1H, 3JHH = 2.5 Hz), 4.04 (t, 1H, 3JHH = 1.8 Hz), 4.17 (t,
1H, 3JHH = 1.8 Hz), 4.31 (t, 1H, 3JHH = 1.1 Hz), 4.36 (t, 1H, 3JHH = 1.3
Hz), 7.14−7.05 (m, 7H), 7.35−7.31 (m, 1H), 7.52−7.43 (m, 4H),
7.80 (d, 1H, 2JHH = 7.8 Hz), 7.94 (d, 1H, 2JHH = 7.6 Hz), 9.69 ppm (s,
1H). 31P{1H} NMR (C6D6, 161 MHz): δ −5.5 ppm. 13C{1H} NMR
(C6D6, 100 MHz): δ 44.6 (s), 57.3 (s), 68.3 (s), 70.5 (s), 71.3 (s), 71.4
(s), 73.2 (s), 74.9 (s), 75.5 (s), 80.4 (s), 83.8 (s), 89.2 (s), 128.2 (s),
128.4 (d, 3JCP = 7.4 Hz), 128.6 (d, 2JCP = 17.2 Hz), 128.6 (d, 3JCP = 4.0
1
2
2
133.1 (d, JCP = 19.3 Hz), 136.2 (d, JCP = 26.9 Hz), 136.7 (d, JCP
=
3
25.2 Hz), 137.9 (d, JCP = 8.5 Hz), 147.9 ppm (s). EI MS: m/z
(relative intensity, %) 587 (100) [M]+, 543 (22), 507 (9), 464 (6),
403 (15), 387 (32), 294 (11), 267 (14), 202 (15), 183 (15), 115 (13),
58 (45), 44 (16). Anal. Calcd for C29H27BrFeNPS: C, 59.20; H, 4.63;
N, 2.38. Found: C, 59.63; H, 4.89; N, 2.40.
3
2
Hz), 128.7 (d, JCP = 4.1 Hz), 129.6 (s), 132.2 (d, JCP = 21.8 Hz),
2
2
2
133.9 (d, JCP = 19.3 Hz), 134.0 (d, JCP = 19.3 Hz), 134.2 (d, JCP
17.7 Hz), 137.6 (d, JCP = 11.0 Hz), 137.7 (d, JCP = 11.3 Hz), 137.9
(d, JCP = 11.9 Hz), 137.9 (d, JCP = 6.1 Hz), 191.8 ppm (s). EI MS:
m/z (relative intensity, %) 531 (100) [M]+, 516 (34), 503 (36), 486
(61), 460 (49), 394 (20), 339 (14), 302 (18), 274 (18), 257 (20), 183
(40), 152 (18), 121 (14), 58 (32). Anal. Calcd for C32H30FeNOP: C,
72.33; H, 5.69; N, 2.64. Found: C, 72.50; H, 5.97; N, 2.75.
=
1
1
1
3
1-Diphenylphosphino-1′-carboxaldehyde-2-N,N-dimethyl-
n
aminomethylferrocene (rac-12). A 1.9 mL portion of BuLi in n-
hexane (1.66 M, 3.11 mmol, 1.05 equiv) was added dropwise at −40
°C to a solution of 1.5 g (2.96 mmol) of 1-diphenylphosphino-1′-
bromo-2-N,N-dimethylaminomethylferrocene (rac-3) in 30 mL of n-
hexane. The reaction mixture was stirred, and the temperature of the
reaction mixture was kept at −10 °C. After 2 h, the clear orange
solution was cooled to −40 °C, 0.9 mL of DMF (0.012 mmol, 4
equiv) was added, and the obtained brown suspension was stirred
overnight at room temperature. Approximately 20 mL of water was
added and the reaction mixture extracted with ethyl acetate (3 × 15
mL). The organic phases were combined, dried with MgSO4, and
filtered, and the solution was concentrated by using a rotary
1-(5-Diphenylphosphino)thienyl-1′-carboxaldehyde-2-N,N-
dimethylaminomethylferrocene (rac-15). The compound was
synthesized by using the same procedure as for the synthesis of rac-12.
The compound rac-15 was obtained as an orange powder in 83% yield.
1
Mp: 56−61 °C. H NMR (C6D6, 400 MHz): δ 2.01 (s, 6H), 2.75 (d,
1H, 2JHH = 13.1 Hz), 3.65 (d, 1H, 2JHH = 12.1 Hz), 3.84 (t, 1H, 2JHH
=
2.4 Hz), 3.95 (s br, 2H), 3.97 (s br, 1H), 4.24 (s, 1H), 4.39−4.37 (m,
2H), 7.18−7.06 (m, 7H), 7.43 (d, 1H, 3JHH = 3.1 Hz), 7.56−7.52 (m,
5859
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Organometallics
Article
Table 6. Crystal Data and Structure Refinement Details for Compounds rac-3 (at 293 and 130 K), rac-7, and rac-11
rac-3 (293 K)
rac-3 (130 K)
rac-7
rac-11
formula
fw
C25H25BrFeNP
506.19
C25H25BrFeNP
506.19
C31H29BrFeNOP
598.28
C29H27BrFeNPS
588.31
T (K)
293(2)
130(2)
130(2)
130(2)
cryst syst
space group
a (pm)
b (pm)
c (pm)
α (deg)
β (deg)
γ (deg)
V (nm3)
Z
monoclinic
P21/c
triclinic
triclinic
monoclinic
P21/c
P1
̅
P1
̅
1027.75(4)
2269.76(8)
1092.31(5)
90
1024.5(1)
2231.8(3)
1070.4(1)
88.383(9)
115.39(1)
90.62(1)
852.46(2)
1087.89(4)
1564.66(6)
73.740(3)
88.534(3)
71.886(3)
1.32095(8)
2
1556.84(4)
1288.09(2)
1305.06(3)
90
115.071(5)
90
102.172(2)
90
2.3080(2)
4
2.2101(4)
4
2.5583(1)
4
Dcalcd (Mg/m3)
1.457
1.521
1.504
1.527
μ (mm−1
)
2.465
2.574
2.169
2.314
F(000)
1032
1032
612
1200
cryst size (mm)
θ range (deg)
h,k,l ranges
0.5 × 0.15 × 0.05
2.90−26.37
−12 ≤ h ≤ 12
−28 ≤ k ≤ 28
−13 ≤ l ≤ 13
4708 [0.0450]
1.031
0.5 × 0.15 × 0.05
2.86−26.37
−12 ≤ h ≤ 12
−27 ≤ k ≤ 27
−13 ≤ l ≤ 13
0.35 × 0.25 × 0.2
2.90−33.14
−13 ≤ h ≤ 13
−16 ≤ k ≤ 16
−24 ≤ l ≤ 24
10060 [0.0290]
1.056
0.25 × 0.15 × 0.05
3.11−30.51
−22 ≤ h ≤ 22
−18 ≤ k ≤ 18
−18 ≤ l ≤ 18
7806 [0.0449]
1.028
a
no. of indep rflns [Rint]
GOF (F2)
13266 [0.0000]
0.942
R1/wR2 (I > 2σ(I))
R1/wR2 (all data)
residual electron density (e/Å3)
0.0634/0.1394
0.1033/0.1597
0.942/−1.060
0.0571/0.1223
0.0867/0.1301
1.091/−0.838
0.0294/0.0703
0.0400/0.0762
0.508/−0.730
0.0457/0.0979
0.0714/0.1099
2.061/−2.235
a
Twinned crystal.
4H), 9.71 ppm (s, 1H). 31P{1H} NMR (C6D6, 161 MHz): δ −19.4
ppm. 13C{1H} NMR (C6D6, 100 MHz): δ 44.5 (s), 57.5 (s), 68.3 (s),
70.7 (s), 71.0 (s), 71.5 (s), 73.2 (s), 75.1 (s), 75.6 (s), 80.8 (s), 82.2
(s), 84.0 (s), 128.5 (d, JCP = 6.9 Hz), 128.7 (s), 133.3 (d, JCP = 3.1
Hz), 133.3 (d, 3JCP = 3.0 Hz), 136.8 (d, 2JCP = 25.1 Hz), 137.3 (d, 2JCP
= 28.7 Hz), 138.32 (d, 1JCP = 9.7 Hz), 138.4 (d, 1JCP = 9.8 Hz), 147.7
(s), 191.8 ppm (s). EI MS: m/z (relative intensity, %) 537 (100)
[M]+, 522 (26), 509 (29), 492 (26), 352 (19), 308 (26), 280 (22), 267
(14), 183 (19), 121 (17), 58 (31). Anal. Calcd for C30H29FeNOPS: C,
67.04; H, 5.25; N, 2.61. Found: C, 67.50; H, 5.72; N, 2.70.
nitrogen stream. Crystallographic measurements were made with a
Gemini diffractometer (Agilent Technologies). Data were collected by
using monochromated Mo Kα radiation (λ = 71.073 pm). Structure
solution was carried out with SIR92.33 Anisotropic refinement of all
non-hydrogen atoms was achieved with SHELXL-97.33 Hydrogen
atoms were calculated for all structures on idealized positions using the
riding model. Twin law for rac-3 (at 130 K): −1.00 0.00 0.00; −0.01
1.00 −0.12; 0.00 0.00 −1.00. Twin domain ratio: 0.509(1):0.491(1).
ORTEP34 was used for molecular visualization. Crystal data and details
of data collection and refinement are given in Table 6.
3
3
Typical Procedure for Immobilization of 3-Aminopropyl-
trimethoxysilane (APTMS) on Silica Gel. A 5 g portion of 60A
silica gel with particle diameter 0.035−0.070 mm was treated with an
aqueous solution of HCl at room temperature. The suspension was
stirred for 3 h and then filtered and dried under vacuum at 150 °C for
3−4 h. 3-Aminopropyltrimethoxysilane (2 mmol/g of silica gel)
dissolved in dry toluene was added to the dried silica gel under an inert
atmosphere. The mixture was stirred at 120 °C overnight and then
filtered and dried. The unconverted 3-aminopropyltrimethoxysilane
was removed by Soxhlet extraction with diethyl ether. The APS-
modified silica gel was dried under vacuum for 5 h. Elemental analysis:
5.48% C, 1.54% H, 1.52% N. NH2 loading: 1.09 mmol/g. BET surface
area: 430.75 m2/g, Vp = 0.532 cm3/g, dp = 4.195 nm. 13C CP MAS
ASSOCIATED CONTENT
■
S
* Supporting Information
Text giving detailed assignments of 1H, 31P{1H}, 13C{1H}
NMR, EI MS, and IR spectroscopic data for compounds rac-2−
1
3 and rac-6−15 and H, 31P{1H} NMR and EI MS data of
compounds B−D having a 1,4-phenylene spacer and CIF files
giving crystallographic data for rac-3 (measurement at 293 and
130 K), rac-7, and rac-11. This material is available free of
charge via the Internet at http://pubs.acs.org. CCDC 939444
(rac-3 (at 293 K)), 939445 (rac-3 (at 130 K)), 939446 (rac-7)
and 939447 (rac-11) also contain supplementary crystallo-
graphic data for this paper. These data can be obtained from
The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif.
1
NMR: δ 8.4 (SiCH2), 24.3 (CH2), 43.7 ppm (d, JCN = 134.3 Hz,
CH2NH2). 29Si MAS NMR: δ −58.6 (T2), −66.2 ppm (T3).
Typical Procedure for Grafting of rac-12 to Modified Silica
Gel. The compound rac-12 (0.68 g, 1.5 mmol) was added to 1 g of
APS-modified silica gel suspended in dry toluene. The mixture was
heated to reflux overnight with stirring, and water was removed by
using a Dean−Stark apparatus. The modified silica gel was filtered off
and washed seven times with 15 mL of boiling THF. The obtained rac-
12-modified silica gel was dried under vacuum. Elemental analysis:
8.41% C, 1.88% H, 1.69% N. Fe loading: 1.21 mmol/g. BET surface
area: 411.86 m2/g, Vp = 0.462 cm3/g, dp = 4.020 nm.
AUTHOR INFORMATION
Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS
This work was funded by the European Union and the Free
■
X-ray Structure Determinations. Suitable crystals were mounted
on a glass needle with perfluoropolyalkyl ether and cooled under a
State of Saxony (Europaischer Sozialfonds (ESF) Nachwuchs-
̈
5860
dx.doi.org/10.1021/om400449v | Organometallics 2013, 32, 5852−5861

Organometallics
Article
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