New (1-phosphanylferrocen-1′- and -2-yl)methyl-linked diaminocarbene ligands: Synthesis and rhodium(I) complexes

Article abstract of DOI:10.1002/ejic.200601193

Two ferrocenylmethanols, [1′-(diphenylthiophosphanyl)-ferrocen-1-yl] methanol (3) and [2-(diphenylthiophosphanyl)-ferrocen-1-yl]methanol (6), have been converted in one step into the 1,1′- and 1,2-ferrocenediyl-linked thiophosphane/N-R-imidazolium salts 4a,b and 7a,b (a: R = Me; b: R = 2,4,6-Me₃C₆H₂ or Mes). This straightforward method allows the linkage of an imidazolium group to a ferrocene unit with a nonsubstituted methylene bridge. After desulfurisation of the phosphane group, the ligands reacted with an Rh^I precursor, in the presence of tBuOK, to give cationic complexes 9a,b and 10a,b. All compounds were characterised by elemental analysis, NMR spectroscopy and mass spectrometry. The molecular structures of compounds 4a, 7a and 9a were determined by X-ray crystallography. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200601193

SHORT COMMUNICATION
DOI: 10.1002/ejic.200601193
New (1-Phosphanylferrocen-1Ј- and -2-yl)methyl-Linked Diaminocarbene
Ligands: Synthesis and Rhodium(I) Complexes
Agnès Labande,*[a] Jean-Claude Daran,[a] Eric Manoury,[a] and Rinaldo Poli*[a]
Keywords: Carbene ligands / Phosphane ligands / Ferrocenes / Rhodium
Two ferrocenylmethanols, [1Ј-(diphenylthiophosphanyl)-
ferrocen-1-yl]methanol (3) and [2-(diphenylthiophosphanyl)-
ferrocen-1-yl]methanol (6), have been converted in one step
into the 1,1Ј- and 1,2-ferrocenediyl-linked thiophosphane/N-
R-imidazolium salts 4a,b and 7a,b (a: R = Me; b: R = 2,4,6-
Me3C6H2 or Mes). This straightforward method allows the
linkage of an imidazolium group to a ferrocene unit with a
nonsubstituted methylene bridge. After desulfurisation of the
phosphane group, the ligands reacted with an RhI precursor,
in the presence of tBuOK, to give cationic complexes 9a,b
and 10a,b. All compounds were characterised by elemental
analysis, NMR spectroscopy and mass spectrometry. The mo-
lecular structures of compounds 4a, 7a and 9a were deter-
mined by X-ray crystallography.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
The chemistry of N-heterocyclic carbenes (NHCs) has alcohol 6 is already well known.[7,8] We have adapted this
experienced a very rapid development over the past ten method to prepare the new alcohol 3. It was successfully
years.[1] They have found many applications in catalysis, obtained in two steps from known 1-bromo-1Ј-(diphenyl-
since the corresponding transition metal complexes have phosphanyl)ferrocene,[9] with satisfactory yields.
proven to be very active, robust and generally air-stable.[2]
Ligands associating an NHC and a phosphane have also
shown very interesting properties,[3] in particular for C–C
coupling reactions catalysed by palladium or nickel.[4]
To date, there are only two synthetic methods allowing
the preparation of ferrocenediyl-linked phosphane/NHC li-
gands with an aryl (or ferrocenyl) substituent on the imid-
azole moiety.[5,6] However, the carbon atom situated in α-
position to the Cp ring has a methyl substituent in both cases.
To the best of our knowledge, there is no precedent in the
literature for 1,1Ј-disubstituted ferrocenediyl phosphane/imid-
azolium ligands. On the other hand, the fundamental differ-
ence between our 1,2-disubstituted ligands and previously re-
ported ligands is that the former possess only planar chirality,
whereas the latter have both planar and central chirality.[5,6]
Scheme 1. Synthesis of 1,1Ј-ferrocenediyl ligands. i. a) nBuLi, THF,
–25 °C, b) dmf, –25 °C, c) S8, CH2Cl2, 40 °C (70%); ii. NaBH4, tol-
uene/NaOH, 0 °C (88%); iii. a) HBF4, CH2Cl2, room temp., b) N-
Thus, it becomes possible to study the specific effect of planar
chirality in asymmetric catalytic reactions. We present here a
R-imidazole; iv) Raney Ni, MeCN, room temp. or 80 °C.
new synthetic method for 1,1Ј- and racemic 1,2-disubstituted
ferrocenediyl phosphane/imidazolium ligands, which are pre-
cursors of phosphane/NHCs.
The precursors for the introduction of the imidazolium
moiety are alcohols 3 (Scheme 1) and 6 (Scheme 2). The
synthesis of racemic (as well as enantiomerically pure)
[a] Laboratoire de Chimie de Coordination, UPR CNRS 8241 (lié
par convention à l’Université Paul Sabatier et à l’Institut
National Polytechnique de Toulouse),
205 route de Narbonne, 31077 Toulouse Cedex 4, France
Scheme 2. Synthesis of 1,2-ferrocenediyl ligands. i. a) HBF4,
CH2Cl2, room temp., b) N-R-imidazole; ii) Raney Ni, MeCN, room
temp. or 80 °C.
E-mail: agnes.labande@lcc-toulouse.fr
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2007, 1205–1209
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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A. Labande, J.-C. Daran, E. Manoury, R. Poli
SHORT COMMUNICATION
Procedures for introducing an N-substituted imidazole tuted Cp ring of one molecule and the centroid of the
ring on a ferrocenyl unit can involve the displacement of a C(211)–C(216) phenyl ring of the other one [C(14)–H(14)···
chloride,[10] an acetate,[6,11] or a dimethylamino group.[5] Cg3: C(14)–H(14) 0.93 Å; H(14)···Cg3 3.13 Å; C(14)···Cg3
Bolm et al. described the efficient conversion of ferrocenyl 3.755(3) Å; C(14)–H(14)···Cg3 126.5°]. In 7a, the imid-
alcohols into corresponding imidazolium compounds by a azolium ring and one of the phenyl rings [C(121)–C(126);
two-step procedure.[12,13] However, this method has not C(221)–C(226)] interact through an offset π–π stacking with
been applied so far to introduce aryl or tertiary alkyl a plane-to-plane distance of 3.566(2) Å [3.438(2) Å], a
groups. Here, the imidazolium functionality has been intro- centroid-to-centroid distance of 3.9217(3) Å [3.6301(3) Å]
duced in one-pot procedure from the alcohol, according to and an offset angle of 24.6° [18.7°]. The sulfur atom in 7a
a protocol developed earlier in our group for the introduc- is pointing towards the iron atom, as has been seen with
tion of various nucleophiles on 1,2-disubstituted ferrocene- similar 1,2-disubstituted ferrocenediyl ligands.[8]
diyl phosphanes.[14] The α-carbocation is generated with a
Mild reaction conditions were then required for the
strong acid and reacts with the N-R-imidazole (a: R = Me; phosphane deprotection, compatible with the imidazolium
b: R = 2,4,6-Me3C6H2 or Mes). This method allowed us to moiety. After several attempts, we found that the use of
introduce equally well imidazolium groups bearing a pri- Raney nickel in acetonitrile gave the best results.[16]
mary alkyl or an aryl substituent. The reactions are clean,
(Carbene)rhodium(I) complexes were obtained by depro-
very rapid and high-yielding (Schemes 1 and 2).[15] The tonation of the imidazolium salts in the presence of potas-
structure of the intermediates 4a and 7a was confirmed by sium tert-butoxide and [RhCl(cod)]2 in THF, followed by
X-ray diffraction methods (Figure 1). The bond lengths and chloride abstraction (Scheme 3). The latter step could be
angles in both compounds are all within the expected range. carried out with either NaBF4 in CH2Cl2/H2O, or AgBF4
The imidazolium moiety is exo with respect to the ferrocene in CH2Cl2. The silver reagent results in a faster abstraction
unit, and slightly tilted towards the diphenylphosphanyl process while it does not oxidize the ferrocene unit. Room-
group in the case of 7a. In 4a, the packing is governed by temperature conditions for the deprotonation step resulted
C–H···π interactions involving the H(64) atom of the imid- in good yields (75%) for product 9a, but less satisfactory
azolium group and the centroid of the symmetry-related Cp results were obtained in other cases (i.e. 32% for 10b). How-
ring bearing the imidazolium group [C(64)–H(64)···Cg2i: ever, carrying out the deprotonation at –78 °C raised the
C(64)–H(64) 0.95 Å; H(64)···Cg2i 2.74 Å; C(64)···Cg2i yield of 10b to 77%. This shows that the bulky imidazolium
3.562(5) Å; C(64)–H(64)···Cg2i 144.8°; symmetry code (i): substituent does not negatively affect the coordination pro-
–x + 1, –y + 1, –z + 1], leading to the formation of a centro- cess. Good yields (81%) were also obtained for 9b when
symmetric pseudo dimer. The two molecules within the using the low temperature deprotonation protocol, whereas
asymmetric unit in 7a are also connected through weak C– the yield of 9a was lowered (62%). While the products with
H···π interactions involving the H(14) atom of the substi- the 1,1Ј-disubstituted ligands, 9a,b, were obtained selec-
Figure 1. Molecular views of compounds 4a (left) and 7a (right) with atom labelling scheme. Ellipsoids are plotted at the 50% level. H
atoms have been omitted for clarity. Selected bond lengths [Å] and bond angles [°]: 4a: C(1)–P(1) 1.790(3), C(62)–N(1) 1.324(5), C(62)–
N(2) 1.313(5), C(63)–C(64) 1.330(6); N(2)–C(62)–N(1) 108.6(3); 7a: C(11)–P(1) 1.792(3), C(1)–N(11) 1.317(3), C(1)–N(12) 1.309(4), C(3)–
C(4) 1.333(5); N(11)–C(1)–N(12) 109.7(3); C(21)–P(2) 1.801(3), C(6)–N(21) 1.316(3), C(6)–N(22) 1.323(3), C(7)–C(8) 1.344(4); N(21)–
C(6)–N(22) 109.4(3).
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 1205–1209

(Phosphanylferrocenyl)methyl-Linked Diaminocarbene Ligands
SHORT COMMUNICATION
tively, the reactions with the 1,2-disubstituted ligands
yielded by-products. The selectivity for 10b was almost to-
tal,[17] however, complex 10a was obtained along with an-
other carbene/phosphane complex in a 85:15 ratio.[18,19] It
is reasonable to think that, in the case of 1,2-disubstituted
ligands, the selectivity is affected by the steric encumbrance
of the imidazolium substituent. All complexes are stable in
air and could be purified by filtration through silica gel.
The structure of complex 9a was confirmed by X-ray dif-
fraction methods (see Figure 2). The structure shows a
square-planar geometry with the carbene and phosphane
donors in a cis arrangement. The bond lengths and angles
are again within the expected range for this kind of com-
plexes. The Rh–carbene distance is in accordance with what
Seo obtained with a very similar complex, although the
Rh–P distance is slightly longer in our case [2.3345(8) Å
instead of 2.2935(10) Å in Seo’s RhI complex, which has
two NHC/phosphane ligands coordinated to the metal cen-
tre].[5] However, we do not observe any significant lenghten-
ing of the Rh–C bonds trans to the carbene [Rh(1)–CG1],
with respect to the other Rh–C bonds [Rh(1)–CG2], as is
commonly observed for bifunctional NHC ligands.[5,13] Fi-
nally, no tilting of the Cp rings can be observed upon com-
plexation of the ligand to the rhodium centre [the angles
between the two least-squares Cp planes are 4.66(29)° for
4a and 3.15(24)° for 9a].
Figure 2. Molecular view of compound 9a with atom labelling
scheme. Ellipsoids are plotted at the 50% level. H atoms have been
omitted for clarity. Selected bond lengths [Å] and bond angles [°]:
Rh(1)–C(1) 2.047(3), Rh(1)–P(1) 2.3345(8), Rh(1)–C(21) 2.215(3),
Rh(1)–C(22) 2.231(3), Rh(1)–C(25) 2.220(3), Rh(1)–C(26) 2.217(3),
Rh(1)–CG1 2.1140(3), Rh(1)–CG2 2.1091(3), N(1)–C(1) 1.359(4),
N(2)–C(1) 1.357(4), C(2)–C(3) 1.338(4); C(1)–Rh(1)–P(1) 90.83(8),
C(1)–Rh(1)–CG1 175.91(8), C(1)–Rh(1)–CG2 90.46(8), CG1–
Rh(1)–P(1) 93.26(2), CG2–Rh(1)–P(1) 174.69(2), CG2–Rh(1)–CG1
85.450(10), N(1)–C(2)–N(2) 104.5(2). CG1 and CG2 denote the
C(21)–C(22) centroid and the C(25)–C(26) centroid, respectively.
Table 1. Hydrosilylation of acetophenone with diphenylsilane. Con-
ditions: 1 equiv. of acetophenone, 1.1 equiv. of diphenylsilane,
2 mol-% of catalyst, room temperature.
Entry
Complex
Solvent
t (d)
Conversion (%)[a]
1
2
3
4
9a
9a
CH2Cl2
THF
THF
7
3
3
3
17
46
49
67
9b
10b
THF
[a] Determined by 1H NMR spectroscopy after hydrolysis of the
silylated intermediate.
In conclusion, we have prepared new ferrocenediyl phos-
phane/imidazolium ligands by a general and effective
method. Further tests will be carried out to evaluate the
activity of the RhI complexes in various catalytic reactions.
Enantiomerically pure 1,2-disubstituted ligands will also be
prepared and tested in the asymmetric version of the reac-
tions. Results will be published in due course.
Scheme 3. Synthesis of Rh complexes. i. tBuOK, [Rh(cod)Cl]2,
THF; ii. NaBF4, CH2Cl2/H2O, room temp. or AgBF4, CH2Cl2,
room temp.
Preliminary tests have been carried out to evaluate the
activity of complexes 9a, 9b and 10b (racemic mixture) for
the hydrosilylation of ketones. The reaction of diphenyl-
silane with acetophenone was carried out in dichlorometh- Experimental Section
ane or THF at room temperature, with 2 mol-% of catalyst
General: All reactions were carried out under dry argon using
(Table 1). The first results show that THF is a better sol-
vent, despite the low solubility of complexes 9a and 9b, and
that the complex bearing a 1,2-disubstituted ligand is more
active. All complexes show a moderate activity, compared
with other literature benchmarks.[13,20]
Schlenk glassware and vacuum-line techniques. Solvents for synthe-
ses were dried and degassed by standard methods before use. N,N-
Dimethylformamide (dmf) was purified by distillation from CaH2.
Spectra were recorded with a Bruker AM250, a Bruker AV300 or
a Bruker AV500 spectrometer. All spectra were recorded in CDCl3,
Eur. J. Inorg. Chem. 2007, 1205–1209
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1207

A. Labande, J.-C. Daran, E. Manoury, R. Poli
SHORT COMMUNICATION
unless otherwise stated. Mass spectra were obtained from acetoni-
trile solutions with a TSQ7000 instrument from ThermoElectron.
+ Cp), 4.52 (br. s, 1 H, Cp), 4.41 (br. s, 5 H, CpЈ), 3.81 (br. s, 1 H,
Cp), 3.52 (br. s, 3 H, CH3Im+) ppm. 13C{1H} NMR (125.8 MHz,
CDCl3, 25 °C): δ = 135.9 (NCN+), 134.0 (d, JP,C = 85.6 Hz,
1
All new compounds described were fully characterised by H, 13C,
and 31P NMR spectroscopy, elemental analysis and mass spectrom-
etry. 1,1Ј-dibromoferrocene and 1-bromo-1Ј-(diphenylphosphanyl)-
ferrocene were prepared according to literature procedures.[9]
2ϫquat. PPh2), 132.2–131.8 (m, 5ϫPPh2), 131.4 (d, JP,C =
10.1 Hz, 2ϫPPh2), 128.7 (d, JP,C = 12.6 Hz, PPh2), 128.45 (d, JP,C
= 12.6 Hz, 2ϫPPh2), 123.6 (C=C, Im+), 122.4 (C=C, Im+), 83.4
(d, JP,C = 11.3 Hz, quat. Cp), 77.5–77.0 (Cp + CDCl3), 76.3 (d, JP,C
= 11.3 Hz, Cp), 74.3 (d, JP,C = 94.4 Hz, quat. Cp), 71.4 (CpЈ), 71.3
(Cp), 48.2 (CH2Im+), 37.0 (CH3Im+) ppm. 31P{1H} NMR
(202.5 MHz, CDCl3, 25 °C): δ = 40.7 ppm. MS (ESI): m/z (%) =
497 (37) [M+], 415 (100) [M+ – C4H6N2].
General Procedures for the Preparation of Imidazolium Salts: To
a solution of 3 (100 mg, 0.23 mmol) in degassed dichloromethane
(5 mL) was quickly added HBF4 (35 µL, 54wt-% in Et2O), immedi-
ately followed by an N-substituted imidazole (0.35 mmol). The
mixture was washed with 2  aq. HCl, water, satd. aq. NaHCO3
and water again. The organic phase was dried (MgSO4), filtered
and concentrated in vacuo. Methyl-substituted salts: the residue
was taken up in dichloromethane (1 mL), diethyl ether was added
and the orange precipitate was filtered, washed with diethyl ether
and dried in vacuo to give a yellow-orange solid. Mesityl-substi-
tuted salts: the residue was purified by column chromatography on
silica gel (eluent: CH2Cl2/acetone, 9:1) to give a yellow-orange so-
lid. Similar yields were obtained starting from 500 mg of 3.
Imidazolium Salt 7b: 121 mg, 76% yield. C35H34BF4FeN2PS
(688.36): calcd. C 61.07, H 4.98, N 4.07; found C 60.34, H 4.93, N
3.98. 1H NMR (300 MHz, CDCl3, 25 °C): δ = 8.67 (s, 1 H,
NCHN+), 7.84–7.77 (m, 2 H, PPh2), 7.58–7.28 (m, 9 H, PPh2
+
HC=C Im+), 6.92 (s, 2 H, Mes), 6.71 (s, 1 H, HC=C Im+), 6.66 (d,
JH,H = 14.3 Hz, 1 H, CH2Im+), 5.58 (d, JH,H = 14.3 Hz, 1 H,
CH2Im+), 5.31 (br. s, 1 H, Cp), 4.56 (br. s, 1 H, Cp), 4.35 (s, 5 H,
CpЈ), 3.96 (br. s, 1 H, Cp), 2.30 (s, 3 H, p-CH3 Mes), 1.84 (br. s, 3
H, o-CH3 Mes), 1.68 (br. s, 3 H, o-CH3 Mes) ppm. 13C{1H} NMR
(75.5 MHz, CDCl3, 25 °C): δ = 141.2 (quat. Mes), 136.2 (NCN+),
135.0 (d, JP,C = 86.0 Hz, quat. PPh2), 134.2 (quat. Mes), 132.3 (d,
Imidazolium Salt 4a: 86 mg, 64% yield. Single crystals suitable for
X-ray diffraction studies were obtained by slow concentration of
a dichloromethane solution. C27H26BF4FeN2PS (584.21): calcd. C
55.51, H 4.49, N 4.80; found C 54.98, H 4.16, N 4.55. 1H NMR
(300 MHz, CD2Cl2, 25 °C): δ = 8.65 (s, 1 H, NCHN+), 7.79–7.72
(m, 4 H, PPh2), 7.59–7.47 (m, 6 H, PPh2), 7.29 (s, 1 H, HC=C
Im+), 7.27 (s, 1 H, HC=C Im+), 5.09 (s, 2 H, Cp), 4.69 (s, 2 H,
Cp), 4.54 (s, 2 H, Cp or CH2Im+), 4.50 (s, 2 H, Cp or CH2Im+),
4.16 (s, 2 H, Cp), 3.88 (s, 3 H, CH3Im+) ppm. 13C{1H} NMR
JP,C = 87.3 Hz, quat. PPh2), 132.0 (d, JP,C = 11.0 Hz, 2ϫPPh2
+
d, JP,C = 3.1 Hz, PPh2), 131.7 (d, JP,C = 2.9 Hz, PPh2), 131.4 (d, JP,C
= 10.5 Hz, 2ϫPPh2), 130.5 (quat. Mes), 129.7 (C-H Mes), 128.6 (d,
JP,C = 12.4 Hz, 2ϫPPh2), 128.3 (d, JP,C = 12.7 Hz, 2ϫPPh2), 122.9
(C=C Im+), 122.2 (C=C Im+), 83.6 (d, JP,C = 12.3 Hz, quat. CpC),
76.9 (d, JP,C = 8.6 Hz, Cp), 75.7 (d, JP,C = 11.4 Hz, Cp), 72.9 (d,
JP,C = 94.5 Hz, quat. CpP), 71.8 (d, JP,C = 10.1 Hz, Cp), 71.4 (CpЈ),
48.0 (CH2Im+), 21.0 (p-CH3 Mes), 17.2 (2ϫo-CH3 Mes) ppm.
31P{1H} NMR (121.5 MHz, CDCl3, 25 °C): δ = 40.4 ppm. MS
(ESI): m/z (%) = 601 (100) [M+], 415 (27) [M+ – C12H14N2], 187
(20).
(75.5 MHz, CD2Cl2, 25 °C): δ = 135.5 (NCN+), 134.2 (d, JP,C
87.0 Hz, 2ϫquat. PPh2), 131.55 (2ϫPPh2), 131.53 (d, JP,C
=
=
10.6 Hz, 4ϫPPh2), 128.4 (d, JP,C = 12.5 Hz, 4ϫPPh2), 123.6 (C=C
Im+), 121.8 (C=C Im+), 80.4 (quat. CpC), 76.2 (d, JP,C = 96.9 Hz,
quat. CpP), 74.1 (d, JP,C = 12.4 Hz, 2ϫCpP), 73.1 (d, JP,C
=
10.0 Hz, 2ϫCpP), 71.7 (2ϫCpC), 71.3 (2ϫCpC), 49.1 (CH2Im+),
36.3 (CH3Im+) ppm. 31P{1H} NMR (81.0 MHz, CD2Cl2, 25 °C): δ
Supporting Information (see footnote on the first page of this arti-
cle): Full experimental details, 1H, 13C and 31P NMR spectroscopic
data, mass spectrometric data and elemental analyses for all new
compounds. Crystal data for 4a, 7a and 9a (CCDC-616649
to -616651 contain the supplementary crystallographic data for
this paper; these data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
datarequest/cif).
= 41.0 ppm. MS (ESI): m/z (%) = 497 (70) [M+], 415 (100) [M+
–
C4H6N2].
Imidazolium Salt 4b: 96 mg, 60% yield. C35H34BF4FeN2PS
(688.36): calcd. C 61.07, H 4.98, N 4.07; found C 60.31, H 4.71, N
3.91. 1H NMR (300 MHz, CD3CN, 25 °C): δ = 8.54 (s, 1 H,
NCHN+), 7.80–7.73 (m, 4 H, PPh2), 7.60–7.50 (m, 7 H, PPh2
+
HC=C Im+), 7.40 (s, 1 H, HC=C Im+), 7.11 (s, 2 H, Mes), 5.15
(br. s, 2 H, CH2Im+), 4.71 (br. s, 2 H, Cp), 4.55 (br. s, 2 H, Cp),
4.51 (br. s, 2 H, Cp), 4.18 (br. s, 2 H, Cp), 2.36 (s, 3 H, p-CH3
Mes), 2.00 (s, 6 H, o-CH3 Mes) ppm. 13C{1H} NMR (75.5 MHz,
CD3CN, 25 °C): δ = 141.2 (quat. Mes), 135.8 (NCN+), 134.7
(2ϫquat. Mes), 134.4 (d, JP,C = 87.0 Hz, 2ϫquat. PPh2), 131.7 (d,
JP,C = 2.9 Hz, 2ϫPPh2), 131.4 (d, JP,C = 10.7 Hz, 4ϫPPh2), 131.0
(quat. Mes), 129.5 (2ϫC-H Mes), 128.5 (d, JP,C = 12.5 Hz,
4ϫPPh2), 124.2 (C=C Im+), 122.7 (C=C Im+), 80.7 (quat. CpC),
76.1 (d, JP,C = 97.3 Hz, quat. CpP), 74.0 (d, JP,C = 12.4 Hz,
2ϫCpP), 73.2 (d, JP,C = 10.1 Hz, 2ϫCpP), 71.6 (2ϫCpC), 71.2
(2ϫCpC), 49.2 (CH2Im+), 20.2 (p-CH3 Mes), 16.6 (2ϫo-CH3 Mes)
ppm. 31P{1H} NMR (121.5 MHz, CD3CN, 25 °C): δ = 40.6 ppm.
MS (ESI): m/z (%) = 601 (100) [M+], 415 (100) [M+ – C12H14N2].
Acknowledgments
We thank the CNRS for support of this work and Yannick Coppel
for NMR analysis of the rhodium complexes.
[1] D. Bourissou, O. Guerret, F. P. Gabbai, G. Bertrand, Chem.
Rev. 2000, 100, 39.
[2] W. A. Herrmann, Angew. Chem. Int. Ed. 2002, 41, 1290–1309;
N. M. Scott, S. P. Nolan, Eur. J. Inorg. Chem. 2005, 1815–1828.
[3] N. Stylianides, A. A. Danopoulos, N. Tsoureas, J. Organomet.
Chem. 2005, 690, 5948–5958; L. D. Field, B. A. Messerle, K. Q.
Vuong, P. Turner, Organometallics 2005, 24, 4241–4250.
[4] C. Yang, H. M. Lee, S. P. Nolan, Org. Lett. 2001, 3, 1511–1514;
J. Wolf, A. Labande, J.-C. Daran, R. Poli, J. Organomet. Chem.
2006, 691, 433–443; J. Wolf, A. Labande, M. Natella, J.-C. Da-
ran, R. Poli, J. Mol. Catal. A 2006, 259, 205–212.
[5] H. Seo, H.-J. Park, B. Y. Kim, J. H. Lee, S. U. Son, Y. K.
Chung, Organometallics 2003, 22, 618–620.
[6] S. Gischig, A. Togni, Organometallics 2004, 23, 2479–2487.
[7] T. Hayashi, T. Mise, M. Fukushima, M. Kagotani, N. Nagash-
ima, Y. Hamada, A. Matsumoto, S. Kawakami, M. Konishi,
Imidazolium Salt 7a: 96 mg, 71% yield. Single crystals suitable for
X-ray diffraction studies were obtained by slow diffusion of diethyl
ether into a THF solution. C27H26BF4FeN2PS (584.21): calcd. C
55.51, H 4.49, N 4.80; found C 51.53, H 3.90, N 4.32. 1H NMR
(500 MHz, CDCl3, 25 °C): δ = 8.33 (s, 1 H, NCHN+), 7.73–7.33
(m, 10 H, PPh2), 6.98 (br. s, 1 H, HC=C Im+), 6.87 (br. s, 1 H,
HC=C Im+), 6.41 (br. s, 1 H, CH2Im+), 5.15–5.04 (m, 2 H, CH2Im+
1208
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Eur. J. Inorg. Chem. 2007, 1205–1209

(Phosphanylferrocenyl)methyl-Linked Diaminocarbene Ligands
SHORT COMMUNICATION
K. Yamamoto, M. Kumada, Bull. Chem. Soc. Jpn. 1980, 53,
1138–1151.
[8] N. Mateus, L. Routaboul, J.-C. Daran, E. Manoury, J. Or-
ganomet. Chem. 2006, 691, 2297–2310.
[9] T.-Y. Dong, L.-L. Lai, J. Organomet. Chem. 1996, 509, 131–
134; T.-Y. Dong, P.-H. Ho, C.-K. Chang, J. Chin. Chem. Soc.
2000, 47, 421–424.
[10] K. S. Coleman, S. Turberville, S. I. Pascu, M. L. H. Green, J.
Organomet. Chem. 2005, 690, 653–658.
[11] H. Seo, B. Y. Kim, J. H. Lee, H.-J. Park, S. U. Son, Y. K.
Chung, Organometallics 2003, 22, 4783–4791.
[12] C. Bolm, M. Kesselgruber, G. Raabe, Organometallics 2002, 21,
707–710.
from alcohol 3) failed to give the expected compound, or the
reactions were neither selective nor effective.
[16] D. Liu, W. Tang, X. Zhang, Org. Lett. 2004, 6, 513–516.
[17] Along with the doublet attributed to 10b in the 31P NMR spec-
trum, a second, weak doublet can be observed. However, no
other compound can be detected apart from 10b in the 1H
NMR spectrum.
[18] The yield of 10a is not given, as we obtained an inseparable
mixture of two compounds.
1
[19] The H NMR signals of the minor compound indicate that it
might be a rhodium complex bearing two carbene/phosphane
ligands and no cod ligand.
[20] V. César, S. Bellemin-Laponnaz, H. Wadepohl, L. H. Gade,
Chem. Eur. J. 2005, 11, 2862–2873.
[13] Y. Yuan, G. Raabe, C. Bolm, J. Organomet. Chem. 2005, 690,
5747–5752.
Received: December 15, 2006
[14] L. Routaboul, S. Vincendeau, J.-C. Daran, E. Manoury, Tetra-
hedron: Asymmetry 2005, 16, 2685–2690.
Published Online: February 14, 2007
[15] Any attempt to prepare the imidazolium salts by other meth-
ods (generation of chloride, bromide or acetate leaving groups
Eur. J. Inorg. Chem. 2007, 1205–1209
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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