Bis-ylide ligands from acyclic proximal diphosphonium precursors

Article abstract of DOI:10.1002/ejic.201200407

1,2- or 1,3-Phenylene-diphosphonium bis-ylides have been prepared and their stabilities compared by analysis of the effects of the substitution pattern of the phenylene bridge and the steric hindrance of the P-alkyl substituents in the diphosphonium precursors RPh₂P⁺(C₆H ₄)⁺PPh₂R' (R,R' = Me, Et). In the o-phenylene series, the vicinity of the phosphorus centers allows the distal P ⁺/C^- charge separation of the mono-ylide intermediate to be canceled by the formation of a cyclic ylidophosphorane. The ring strain in the latter was released through phenylene-P(δ⁵) bond cleavage to afford relaxed diphosphonium bis-ylides, which were isolated as carbodiphosphorane, or protonated in situ to form bis-phosphonium ylides depending on the bulkiness of the P-alkyl substituents. In the m-phenylene series (with R,R' = Me), the amplified distal P⁺/C^- charge separation proved sufficient to stabilize the corresponding diphosphonium bis-ylide as a chelating ligand of an Rh^I(CO)₂ center, in a complex where the effective δ-donation of the ligand was confirmed by comparison of the IR carbonyl stretching frequencies with those of the isostructural complex previously described in the o-phenylene series. Although disubstituted o-phenylene-diphosphonium bis-ylides cannot be generated by double deprotonation, a m-phenylene isomer could and was used as a chelating electron-rich C₂ ligand in a rhodium(I) complex. Copyright

Full text of DOI:10.1002/ejic.201200407

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DOI: 10.1002/ejic.201200407
Bis-Ylide Ligands from Acyclic Proximal Diphosphonium Precursors
Carine Maaliki,[a,b] Mohammed Abdalilah,[a,b] Cécile Barthes,[a,b] Carine Duhayon,[a,b]
Yves Canac,*[a,b] and Remi Chauvin*[a,b]
Keywords: Ylides / Ylide ligands / Phosphorus / Rhodium / Electrostatic interactions
1,2- or 1,3-Phenylene-diphosphonium bis-ylides have been
prepared and their stabilities compared by analysis of the
effects of the substitution pattern of the phenylene bridge
and the steric hindrance of the P-alkyl substituents in the
carbodiphosphorane, or protonated in situ to form bis-phos-
phonium ylides depending on the bulkiness of the P-alkyl
substituents. In the m-phenylene series (with R,RЈ = Me), the
amplified distal P+/C– charge separation proved sufficient to
diphosphonium precursors RPh2P+(C6H4)+PPh2RЈ (R,RЈ = Me, stabilize the corresponding diphosphonium bis-ylide as a
Et). In the o-phenylene series, the vicinity of the phosphorus
centers allows the distal P+/C– charge separation of the
mono-ylide intermediate to be canceled by the formation of
a cyclic ylidophosphorane. The ring strain in the latter was
released through phenylene–P(σ5) bond cleavage to afford
relaxed diphosphonium bis-ylides, which were isolated as
chelating ligand of an RhI(CO)2 center, in a complex where
the effective σ-donation of the ligand was confirmed by com-
parison of the IR carbonyl stretching frequencies with those
of the isostructural complex previously described in the o-
phenylene series.
thus appears that only the cyclic diphosphonium bis-ylides
2 and 4 can be used as ligands for electron-rich complexes.
The acyclic analogues of these bis-ylides, in which the
covalent constraint is minimized, have been investigated in
detail, with both o- and m-phenylene bridges. The results
are disclosed herein and discussed by comparison to their
cyclic analogues.[3]
Introduction
Beyond their ubiquitous role in organic synthesis as
Wittig-type reactants for the olefination of carbonyl com-
pounds, phosphonium ylides in their more or less stabilized
versions exhibit rich coordination chemistry as carbon li-
gands of transition metals[1] in either a mono- or bidentate
manner. In general, chelating ligands have been designed to
control not only the electron-donating properties, but also
the stability and stereoselectivity of complexation.[2]
A general classification of diphosphonium bis-ylides has
recently been proposed based on the bridge length (from
fused to ω- and α-bis-ylides) and the orientation of the P+–
C–/P+–C– sequence (head-to-head, tail-to-tail, or head-to-
tail).[3] The preparation and stability of cyclic head-to-head
diphosphonium bis-ylides constrained in five-, six-, and
seven-membered rings have been systematically com-
pared.[4] Indeed, although the fused bis-ylide 2 and the β-
bis-ylide 4 are stable, the α-bis-ylide 3a is destabilized by
the repulsion between the two vicinal negative charges,
leading, after fragmentation, to o-bis(diphenylphosphanyl)-
benzene (o-ddpb, 1) and acetylene. Nevertheless, delocaliza-
tion of the negative charge over the carbonyl C-substituents
allowed the α-bis-ylide 3b to be isolated (Scheme 1).[3] It
Results and Discussion
Previously Obtained Preliminary Results: Dimethyl o-
Phenylene-Diphosphonium 5
The acyclic dimethyl diphosphonium 5 was readily pre-
pared in 90% yield by reaction of o-dppb[5] (1) with an ex-
cess of methyl triflate (Figure 1).[4] All attempts at generat-
ing the corresponding bis-ylide 6 by deprotonation were,
however, unsuccessful. This was attributed to the formation
of the cyclic five-membered-ring ylide 7, which results from
instant attack of the mono-ylide intermediate at the adja-
cent phosphonium center. The cyclic ylidophosphorane 7,
which exists as a mixture of two stereoisomers in a 95:5
ratio corresponding to different occupations of the axial
and equatorial positions of the trigonal-bipyramidal config-
uration, was shown to slowly rearrange into the carbodi-
[a] CNRS, LCC (Laboratoire de Chimie de Coordination),
205, route de Narbonne, 31077 Toulouse, France
Fax: +33-5-61553003
E-mail: yves.canac@lcc-toulouse.fr
chauvin@lcc-toulouse.fr
Homepage: http://www.lcc-toulouse.fr
[b] Université de Toulouse, UPS, INP, LCC,
31077 Toulouse, France
phosphorane
8
upon phenylene–P(σ5) bond cleavage
(Scheme 2),[6] in accord with the mechanism for the trans-
formation 5Ǟ8, reported previously by Schmidbaur et al.[7]
In view of the unfavorable formation of ylidophosphor-
anes of type 7, more hindered ethyl substituents were intro-
Eur. J. Inorg. Chem. 0000, 0–0
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Scheme 1. Vicinal o-phenylene-bridged diphosphoniums 2–4·(HX)2 salts and ylides thereof.
Scheme 2. Preparation of the carbodiphosphorane 8 from the acyclic diphosphonium 5 via the cyclic ylidophosphorane 7.
duced at the phosphorus atoms through the preparation of
the mixed ethyl methyl diphosphonium 10 and the diethyl
homologue 11.
P-Ethyl-Substituted o-Phenylene-Diphosphoniums 10 and 11
The diphosphane 1 was treated with ethyl triflate in
1,1,2,2-tetrachloroethane (tce) at 110 °C for 12 h to give the
phosphanyl-phosphonium cation 9 in 86% yield.[8] A sec-
ond alkylation reaction with methyl triflate in the same sol-
vent at 110 °C for 24 h allowed the mixed diphosphonium
10 to be isolated in 31% yield (Scheme 3). The more steri-
cally demanding diethyl diphosphonium 11 was then ob-
tained in 46% yield by treatment of the phosphonium 9
with an excess of ethyl triflate (7 equiv.) in tce for 72 h
(Scheme 3).
The 31P NMR chemical shifts observed for 10 and 11 are
characteristic of phosphonium derivatives [10: δP
+26.3 ppm, d, JPP = 6.1 Hz, and +29.7 ppm, d, JPP
6.1 Hz; 11: δP = +30.6 ppm, s]. Their structures were unam- from o-dppb via the mono-ethyl phosphonium 9.
=
=
Scheme 3. Preparation of the acyclic diphosphoniums 10 and 11
2
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Bis-Ylide Ligands from Diphosphoniums
biguously confirmed by X-ray diffraction analysis of color-
less single crystals (Figure 1).[9] The steric strain is revealed
by the torsional P1–C1–C2–P2 bond angles at the o-phenyl-
ene bridge, which increase significantly from the less-hin-
dered dimethyl diphosphonium 5 to the more hindered di-
ethyl diphosphonium 11 (5: 2.5°; 10: 6.4°; 11: 13.4°). These
values can be attributed to both electrostatic and steric re-
pulsions between the phosphonium fragments. The intro-
duction of a second ethyl substituent also results in an in-
crease in the trans annular P+···P+ distance (3.73 Å in 11 vs.
3.66 Å in 10), enforced by the steric strain and still induced
by the electrostatic repulsion.
The bis-ylide 10b was first envisaged by deprotonation of
10 with 2 equiv. of n-butyllithium in thf at –78 °C. Multinu-
clear NMR monitoring showed the immediate disappear-
ance of the starting diphosphonium 10 with concomitant
formation of the five-membered cyclic ylide 10c as a mix-
ture of two stereoisomers in a ratio of 95:5. As in the case
of the dimethyl analogue, the ylidophosphorane 10c results
from nucleophilic attack of the mono-ylide at the vicinal
phosphonium center of the first mono-ylide intermediate
10a. The initial deprotonation step occurred at the most
acidic alkyl substituent, namely the P+–CH3 moiety
(Scheme 4).
The structure of 10c was first assigned on the basis of
the 31P NMR analysis (δP = –1.6 and –89.8 ppm; JPP
=
57.6 Hz for the major isomer). The CH ylide moiety was
evidenced by 1H and 13C NMR spectroscopy [δCH
+0.43 ppm, dd, JHP(σ4) = 20.0, JHP(σ5) = 15.0 Hz; δCH
=
=
+13.1 ppm, dd, JCP(σ4) = 113.0, JCP(σ5) = 167.0 Hz]. As in
the case of 7 (see Scheme 2), the existence of two stereoiso-
mers is explained by the trigonal-bipyramidal geometry at
the pentacoordinate phosphorus center. Finally, the cyclic
intermediate 10c underwent protonative rearrangement to
the open bis-phosphonium ylide 10e, which was isolated in
62% overall yield.[10] The latter appeared as an AX system
in the 31P NMR spectrum [δP = +19.3 ppm, d, JPP
=
24.3 Hz (PPh3); +24.2 ppm, d, JPP = 24.3 Hz (PPh2Et)].
1
The ylidic CH fragment was also evidenced by H and 13C
NMR spectroscopy (δCH = +2.05 ppm, pseudo-t, JHPPh3
=
JHPPh2Et = 5.0 Hz; δCH = –6.3 ppm, dd, JCPPh3 = 122.0,
JCPh2Et = 124.6 Hz). The formation of 10e results from the
protonation of the diphosphonium bis-ylide intermediate
10d, which was characterized at –30 °C by 31P and 13C
NMR spectroscopy [δP
=
+40.2 ppm, d, (Ph2P+C2);
+31.9 ppm, d, (Ph3P+C), JPP = 51.6 Hz; δCH = +5.6 ppm,
br. s, and +13.7 ppm, m]. The latter was generated by phen-
ylene–P(σ5) bond cleavage via the putative transient phen-
ylide phosphonium intermediate I (Scheme 4).
Figure 1. Views of the X-ray crystal structures of the diphosphoni-
ums 5 (top), 10 (middle), and 11 (bottom), with thermal ellipsoids
drawn at the 30% probability level (the triflate anions and H atoms
have been omitted for clarity). Selected bond lengths [Å] and angles
[°] for 5: C1–P1 1.823(4), C32–P1 1.778(4), C1–C2 1.429(8), P1–
C1–C2 128.56(12), C1–P1–C32 113.71(18);[4] for 10: C1–P1
1.8279(17), C2–P2 1.8206(17), C32–P1 1.8058(18), C1–C2 1.428(2),
P1–C1–C2 127.94(12), P2–C2–C1 127.54(13), C1–P1–C32
112.63(8); for 11: C1–P1 1.826(3), C2–P2 1.817(3), C33–P1
1.800(3), C1–C2 1.428(4), P1–C1–C2 129.3(2), P2–C2–C1 128.4(2),
C1–P1–C33 114.79(14).
As a single ethyl substituent was not sufficient to prevent
intramolecular rearrangement to the cyclic ylidophosphor-
ane 10c, the deprotonation reaction was tested starting
from the more hindered diethyl diphosphonium 11. Again,
the addition of 2 equiv. of n-butyllithium in [D8]thf at
–78 °C was monitored by multinuclear NMR methods. In
spite of the presence of the bulkier ethyl substituents at
both the P atoms, the cyclic ylidophosphorane 11c was
again formed, as indicated by the corresponding 31P chemi-
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Scheme 4. Preparation of the bis-phosphonium ylides 10e and 11e from the acyclic diphosphoniums 10 and 11 via the cyclic ylidophos-
phoranes 10c and 11c and the diphosphonium bis-ylides 10d and 11d, respectively.
cal shifts (δP = +10.1, –88.3 ppm; JPP = 94.2 Hz). The pres- tion (Scheme 4). The structure of 11e was assigned on the
ence of an ylidic C-Me moiety was confirmed by 13C NMR basis of the 1H and 13C NMR spectra (δCCH3 = +1.83 ppm,
spectroscopy [δCMe = +5.7 ppm, dd, JCP(σ4) = 120.0, JCP(σ5) pseudo-t, JHPPh3 = JHPPh2Et = 15.0 Hz; δCMe = –2.0 ppm,
= 172.0 Hz; δCCH3 = +12.6 ppm, pseudo-t, JCP(σ4) = JCP(σ5) br. s). The exact structure of 11e was obtained by X-ray
= 13.8 Hz]. In contrast to the previous cases, a single stereo- diffraction analysis of a single crystal deposited from
isomer of 11c was observed, likely because of the enhanced CH2Cl2 (Figure 2).[9] The cation exhibits a delocalized di-
hindrance of the ethyl substituent. By variable-temperature phosphorallyl structure with a central sp2-hybridized planar
31P NMR monitoring up to room temperature, the cyclic tricoordinate ylidic carbon center (Σ°-C1 = 359.68°) and
intermediate 11c was shown to undergo protonative re- similar P–C(sp2) bond lengths [C1–P1 1.7230(14), C1–P2
arrangement to the bis-phosphonium ylide 11e [δP
+25.4 ppm, d, JPP = 53.7 Hz (PPh3); +28.8 ppm, d, JPP
=
=
1.7135(14) Å], revealing a resonance structure between ca-
nonical C–P (ca. 1.80–1.85 Å) and C=P (ca. 1.60–1.65 Å)
53.7 Hz (PPh2Et)] in 82% overall yield, likely by a mecha- bond types.[11] The system features a distorted U-shaped
nism similar to that proposed for the 10cǞ 10e transforma- H5C6–Ph2P–C(Me)–PPh2–CH2Me four-bond sequence.
The m-phenylene bridge then was envisaged as an alter-
native for separating the two phosphonium fragments in re-
mote positions.
Dimethylated m-Phenylene-Diphosphonium 13
1,3-Bis(diphenylphosphanyl)benzene (12) was first pre-
pared by following a recent procedure reported by James
and co-workers.[12] The addition of 2 equiv. of methyl
triflate to 12 in CH2Cl2 afforded the targeted m-phenylene-
diphosphonium 13 in 86% yield (Scheme 5). The single 31P
NMR signal (δP = +22.5 ppm, s) is in agreement with a
symmetrical structure in solution. The static structure was
determined by X-ray diffraction analysis of single crystals
deposited from a CH2Cl2/pentane mixture at –20 °C (Fig-
ure 3).[9] In contrast to the ortho-disubstituted diphosphoni-
ums 5, 10, and 11, the bond angles at the sp2 carbon atoms
of the m-phenylene bridge in 13 are very close to the ideal
VSEPR values (deviation of ca. 0.9° only). As expected, the
P+···P+ distance (ca. 5.55 Å) is longer than the correspond-
ing sum of the van der Waals radii (3.80 Å), thus confirm-
ing the absence of steric/electrostatic strain between the
phosphonium centers. This could a priori favor the forma-
tion of a more stable bis-ylide.
Figure 2. View of the X-ray crystal structure of the bis-ylide 11e
with thermal ellipsoids drawn at the 30% probability level (the
triflate anions and H atoms have been omitted for clarity). Selected
bond lengths [Å] and angles [°].C1–P1 1.7230(14), C1–P2
1.7135(14), C3–P1 1.8223(15), C1–C2 1.529(2), P1–C1–P2
123.89(8), P1–C1–C2 118.11(10), C1–P1–C3 117.84(7).
4
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Bis-Ylide Ligands from Diphosphoniums
the cod/(CO)2 exchange steps in situ in a one-pot sequence.
The addition of a stoichiometric amount of [Rh(cod)2][TfO]
to a thf solution of the bis-ylide 14 followed by treatment
with an excess of CO thus led to the targeted rhodium-
(dicarbonyl) bis-ylide complex 15 in 60% overall yield
(from 13). The presence of a single signal in the 31P NMR
spectrum (δP = +35.6 ppm) indicates a symmetrical struc-
ture in solution. The significant shift of the 31P signal with
respect to the free bis-ylide is in agreement with the ex-
pected ylide–rhodium complex structure. The Rh–CH2
bond was evidenced by multinuclear NMR techniques and,
in particular, by the high-field region and the multiplicity
of the 13C NMR signal of the metalated ylidic carbon atom
(δCH2 = +1.2 ppm, dd, JCP = 40.3, JCRh = 21.5 Hz). The
symmetry of 15 was also demonstrated by the presence of
a single 13CO resonance at +186.3 ppm (d, JCRh = 20.3 Hz)
and the structure was finally confirmed by ESI-MS (m/z =
633.1 [M]+). The carbonyl IR stretching absorptions, which
are currently used for estimating the donor character of co-
ligands, were found at low frequencies (νCO = 1983,
2053 cm–1 in CH2Cl2), very close to those reported for the
Scheme 5. Synthesis of the bis-ylide dicarbonylrhodium complex
15 from m-dppb (12).
analogous ortho-disubstituted rhodium complex (νCO
=
1984, 2051 cm–1).[6] These values confirm that the diphos-
phonium bis-ylide 14 can be considered a strongly donating
carbon ligand and that the nature of the phenylene bridge
(ortho vs. meta isomers) has no influence on the corre-
sponding electronic properties.[13] Only the high-field value
of the 103Rh NMR chemical shift for 15 (δ = +477 ppm)
with respect to the ortho-disubstituted species (δ
=
+983 ppm)[6] could be due to the cone shielding effect of
the phenylene bridge, which is more sterically constrained
above the Rh atom in 15 than in the ortho isomer.
Figure 3. View of the X-ray crystal structure of the diphosphonium
13 with thermal ellipsoids drawn at the 30% probability level (the
triflate anions and H atoms have been omitted for clarity). Selected
bond lengths [Å] and angles [°]: C1–P1 1.785(3), C2–P2 1.780(3),
C3–P1 1.804(2), C5–P2 1.796(2), C2–P2–C5 110.04(13), C1–P1–C3
108.62(12), P2–C5–C4 120.25(18), P1–C3–C4 121.48(17).
However, the bis-ylide rhodium complex 15 proved un-
stable, decomposing in air or under an inert atmosphere to
give a black precipitate. This chemical behavior might be
explained by the zwitterionic rhodate structure involving
two two-bond charge separations with a formal negative
Deprotonation of the m-phenylene-diphosphonium 13 charge at the electropositive RhI center.[14] Complex 15 is
was then investigated by anticipating that the distance be- the second reported example of a rhodate bis-ylide com-
tween the two phosphonium fragments would be sufficient plex.[6]
to prevent the rearrangement. And indeed, NMR monitor-
ing of the deprotonation of 13 with 2 equiv. of n-BuLi in
[D8]thf at low temperature allowed the expected acyclic bis-
Conclusion
ylide 14 to be identified. This result confirms the greater
acidity of the sp3 CH3 groups at the phosphonium frag-
The preparation and characterization of acyclic diphos-
ments with respect to the central sp2 CH group of the m- phonium bis-ylides from the corresponding diphosphonium
phenylene bridge. The 31P NMR spectrum of the solution precursors have been systematically investigated with re-
displays a single signal at +19.6 ppm, which gives a first spect to the steric demand at the phosphorus centers and
indication of the nature and symmetry of the environment the substitution pattern of the phenylene bridge. In the o-
of the phosphorus atoms. The structure of 14 was con- phenylene series, more or less hindered bis-ylides (with H
1
firmed by H and 13C NMR spectroscopy, in particular, by or Me C-substituents) were not observed due to the insta-
high-field signals assigned to the methylene groups at δH
+0.1 ppm (d, JHP = 7.5 Hz) and δC = –5.9 ppm (d, JCP
=
=
bility of the mono-ylide intermediates, which instantly re-
arrange to cyclic ylidophosphoranes (although bulkier Me
98.1 Hz). Note, by warming the [D8]thf solution to room C-substituents could be envisaged, like iPr or tBu, the en-
temperature, slow decomposition of the bis-ylide 14 was ob- hanced nucleophilic character of the ylidic C atom could
served, resulting in a mixture of unidentified products.
still exceed the anticipated steric stabilization of the mono-
The coordination behavior of 14 with a RhI fragment ylide). Subsequent cleavage of the phenylene–P(σ5) bond of
was investigated by performing both the complexation and the ylidophosphorane allowed steric relaxation to bis-phos-
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133.2 (d, JCP = 10.8 Hz, CHar), 130.8 (d, JCP = 12.7 Hz, CHar),
130.6 (d, JCP = 13.3 Hz, CHar), 124.0 (dd, JCP = 7.9, 83.3 Hz, Car),
122.7 (dd, JCP = 8.7, 82.0 Hz, Car), 120.7 (q, JCF = 320.0 Hz,
CF3SO3), 118.9 (d, JCP = 89.3 Hz, Car), 116.7 (d, JCP = 83.9 Hz,
Car), 20.5 (d, JCP = 51.7 Hz, CH2), 11.6 (d, JCP = 55.9 Hz, CH3),
7.0 (d, JCP = 5.5 Hz, CH3) ppm. 31P NMR (CD3CN, 25 °C): δ =
+26.3 (d, JPP = 6.1 Hz), +29.7 (d, JPP = 6.1 Hz) ppm. MS (ES+):
m/z = 639.1 [M – OTf]+. HRMS (ES+): calcd. for C34H32O3F3P2S
[M – OTf]+ 639.1499; found 639.1493.
phonium ylides. In contrast, in the m-phenylene series, in
which the two phosphonium centers are in remote posi-
tions, the bis-ylide could be fully characterized. By reaction
with a cationic rhodium(I) precursor, the latter bis-ylide was
shown to act as a strongly donating carbon ligand, general-
izing recent observations in the ortho series.[6] The role of
steric and electrostatic interactions in the control of struc-
tural and reactivity features of acyclic proximal diphospho-
niums has been highlighted herein.
Diphosphonium 11: Ethyl trifluoromethanesulfonate (1.90 mL,
14.5 mmol) was added to a solution of 9 (1.30 g, 2.08 mmol) in tce
(12.0 mL) and the solution was then stirred for 3 d at 110 °C. After
evaporation of the solvent, an oily residue was obtained. Successive
washing with toluene (2ϫ30 mL), and Et2O (2ϫ30 mL) followed
by recrystallization at –20 °C from thf/Et2O gave 11 as colorless
crystals (770 mg, 46%); m.p. 107–108 °C. 1H NMR (CD3CN,
25 °C): δ = 8.20–8.26 (m, 4 H, Har), 7.83–7.86 (m, 4 H, Har), 7.50–
7.69 (m, 16 H, Har), 2.73–2.80 (m, 4 H, CH2), 1.05–1.10 (m, 6 H,
Experimental Section
General: Diethyl ether, toluene, and thf were dried and distilled
from sodium/benzophenone, pentane, dichloromethane, 1,1,2,2-tet-
rachloroethane (tce), and acetonitrile over P2O5. All other reagents
were used as commercially available. All reactions were carried out
under argon using Schlenk and vacuum-line techniques. 1H, 13C,
and 31P NMR spectra were recorded with Bruker DPX 300 and
Avance 500 spectrometers. Chemical shifts (δ) are given in ppm
with positive values to high frequency measured relative to tet-
ramethylsilane for 1H and 13C NMR, and to H3PO4 for 31P NMR.
Coupling constants (J) are given in Hz. 103Rh chemical shifts are
given to high frequency from δ(103Rh) = 3.16 MHz.
CH3) ppm. 13C NMR (CD3CN, 25 °C): δ = 141.8 (pseudo-t, JCP
=
10.0 Hz, CHar), 135.7 (CHar), 133.1 (d, JCP = 18.5 Hz, CHar), 130.3
(d, JCP = 12.5 Hz, CHar), 129.0 (d, JCP = 7.7 Hz, CHar), 123.4 (dd,
JCP = 8.2, 81.8 Hz, Car), 120.7 (q, JCF = 320.5 Hz, CF3SO3), 117.1
(d, JCP = 84.9 Hz, Car), 19.7 (d, JCP = 50.2 Hz, CH2), 7.2 (d, JCP
= 4.5 Hz, CH3) ppm. 31P NMR (CD3CN, 25 °C): δ = +30.6 ppm.
MS (ES+): m/z = 653.1 [M – OTf]+. HRMS (ES+): calcd. for
C35H34O3F3P2S [M – OTf]+ 653.1656; found 653.1670.
Phosphonium 9: Ethyl trifluoromethanesulfonate (574 μL,
4.48 mmol) was added to a solution of 1 (2.0 g, 4.48 mmol) in tce
(12.0 mL) and the solution was then stirred for 12 h at 110 °C. Af-
ter evaporation of the solvent, the solid residue was washed with
Et2O (30.0 mL), affording 9 as a white powder (2.41 g, 86%); m.p.
68–69 °C. 1H NMR (CD3CN, 25 °C): δ = 7.85–7.50 (m, 14 H, Har),
7.42–7.22 (m, 6 H, Har), 6.99–6.90 (pseudo-t, JHH = JHP+ = 6.9 Hz,
4 H, Har), 3.57 (dq, JHH = 7.5, JHP+ = 12.9 Hz, 2 H, CH2), 1.37
(dt, JHH = 7.5, JHP+ = 20.4 Hz, 3 H, CH3) ppm. 13C NMR
Ylides 10c and 10e: BuLi (2.5 m in hexane, 61 μL, 0.16 mmol) was
added to a solution of 10 (60 mg, 0.08 mmol) in [D8]thf (2.0 mL)
cooled to –78 °C. Monitoring the reaction by low-temperature
NMR allowed the characterization of 10c as a mixture of stereoiso-
mers (95:5). According to NMR spectroscopy, 10c was slowly con-
verted into 10e. After evaporation of the solvent, 10e was obtained
as a white solid (31 mg, 62%).
(CD3CN, 25 °C): δ = 142.8 (dd, JCP+ = 14.9, JCP = 14.9 Hz, C), 10c: Major isomer (95%): 1H NMR ([D8]thf, –30 °C): δ = 7.92–
139.2 (d, JCP+ = 11.3 Hz, CHar), 136.5 (pseudo-t, JCP+ = JCP
11.8 Hz, C), 135.1 (d, JCP+ = 2.8 Hz, CHar), 134.5 (d, JCP+
=
=
7.80 (m, 4 H, Har), 7.67–7.62 (m, 1 H, Har), 7.62–7.50 (m, 6 H,
Har), 7.42–7.36 (m, 1 H, Har), 7.36–7.26 (m, 1 H, Har), 7.26–7.17
(m, 1 H, Har), 7.17–7.05 (m, 3 H, Har), 7.02–6.88 (m, 4 H, Har),
6.88–6.81 (m, 3 H, Har), 2.72–2.83 (m, 2 H, CH2), 1.19–1.14 (m, 3
H, CH3), 0.43 (dd, JHP = 15.0, JHP+ = 20.0 Hz, 1 H, CH) ppm.
2.9 Hz, CHar), 133.3 (dd, JCP+ = 9.6, JCP = 1.9 Hz, CHar), 133.0
(d, JCP = 19.1 Hz, CHar), 131.6 (d, JCP = 9.9 Hz, CHar), 131.3 (d,
JCP+ = 12.4 Hz, CHar), 130.1 (d, JCP+ = 12.6 Hz, CHar), 129.5
(CHar), 128.8 (d, JCP = 7.2 Hz, CHar), 125.3 (dd, JCP+ = 87.1, JCP
= 35.6 Hz, C), 120.7 (q, JCF = 320.0 Hz, CF3SO3), 119.6 (dd, JCP+
13C NMR ([D8]thf, –30 °C): δ = 173.7 (dd, JCP = 23.4, JCP
12.6 Hz, C), 169.3 (dd, JCP = 17.9, JCP = 17.9 Hz, C), 144.0 (d, JCP
=
= 86.3, JCP = 2.6 Hz, C), 19.1 (dd, JCP+ = 53.2, JCP = 15.0 Hz, = 128.3 Hz, C), 132.2 (d, JCP = 10.1 Hz, 4 CHar), 131.3 (2 CHar),
CH2), 7.3 (dd, JCP+ = 5.1, JCP = 1.1 Hz, CH3) ppm. 31P NMR
131.2 (2 CHar), 131.1 (CHar), 130.5 (CHar), 130.1 (CHar), 129.7 (d,
(CD3CN, 25 °C): δ = +26.66 (d, JPP = 23.1 Hz, P+), –15.28 (d, JPP JCP = 5.0 Hz, 2 CHar), 128.6 (d, JCP = 11.7 Hz, CHar), 128.5 (d,
= 23.1 Hz, P) ppm. MS (ES+): m/z = 475.2 [M]+. HRMS (ES+):
JCP = 11.7 Hz, CHar), 127.7 (d, JCP = 8.8 Hz, CHar), 127.0 (d, JCP
= 15.1 Hz, CHar), 126.8 (d, JCP = 15.1 Hz, CHar), 126.5 (CHar),
126.1 (d, JCP = 5.0 Hz, 2 CHar), 125.1 (d, JCP = 37.7 Hz, C), 123.8
calcd. for C32H29P2 [M]+ 475.1744; found 475.1740.
Diphosphonium 10: Methyl trifluoromethanesulfonate (246 μL,
2.24 mmol) was added to a solution of 9 (0.70 g, 1.12 mmol) in tce
(12.0 mL) and the solution was then stirred for 24 h at 110 °C. Af-
ter evaporation of the solvent, an oily residue was isolated. Success-
ive washing with toluene (2ϫ30 mL), and Et2O (2ϫ30 mL) fol-
lowed by recrystallization at –20 °C from thf/Et2O afforded 10 as
colorless crystals (270 mg, 31%); m.p. 126–127 °C. 1H NMR
(CD3CN, 25 °C): δ = 8.27–8.33 (m, 1 H, Har), 8.18–8.22 (m, 1 H,
(CHar), 120.7 (q, JCF = 320.1 Hz, CF3SO3), 27.2 (d, JCP
=
103.2 Hz, CH2), 13.1 (dd, JCP+ = 113.0, JCP = 167.0 Hz, CH), 8.9
(d, JCP = 5.0 Hz, CH3) ppm. 31P NMR ([D8]thf, –30 °C): δ = –89.8
(d, JPP = 57.6 Hz, P), –1.6 (d, JPP = 57.6 Hz, P+) ppm. Minor iso-
mer (5%): 31P NMR ([D8]thf, –30 °C): δ = –83.4 (d, JPP = 54.7 Hz,
P), +1.6 (d, JPP = 54.7 Hz, P+) ppm.
1
10e: M.p. Ͼ250 °C. H NMR (CD2Cl2, 25 °C): δ = 7.70 (d, JHH
=
Har), 8.06–8.14 (m, 1 H, Har), 7.82–7.95 (m, 5 H, Har), 7.55–7.69 15.0 Hz, 10 H, Har), 7.67–7.61 (m, 3 H, Har), 7.57–7.48 (m, 8 H,
(m, 12 H, Har), 7.38–7.42 (m, 4 H, Har), 2.94–3.00 (m, 2 H, CH2P),
2.38 (d, JHP = 13.2 Hz, 3 H, CH3P), 1.12 (td, JHH = 7.4, JHP
Har), 7.44 (td, JHH = 5.0, JHH = 10.0 Hz, 4 H, Har), 2.48–2.42 (m,
2 H, CH2), 2.05 (pseudo-t, JHPPh3 = JHPPh2Et = 5.0 Hz, 1 H, CH),
=
20.6 Hz, 3 H, CH3) ppm. 13C NMR (CD3CN, 25 °C): δ = 142.8 1.13–1.08 (m, 3 H, CH3) ppm. 13C NMR (CD2Cl2, 25 °C): δ =
(dd, JCP = 11.5, 11.6 Hz, CHar), 142.2 (pseudo-t, JCP = 10.6 Hz,
CHar), 141.5 (pseudo-t, JCP = 10.0 Hz, CHar), 136.0 (d, JCP
133.1 (d, JCP = 10.1 Hz, 6 CHar), 132.8 (d, JCP = 2.5 Hz, 3 CHar),
132.4 (d, JCP = 10.1 Hz, 4 CHar), 132.3 (d, JCP = 2.5 Hz, 2 CHar),
=
2.7 Hz, CHar), 135.7 (d, JCP = 3.1 Hz, CHar), 135.6–136.0 (m, 129.2 (d, JCP = 12.6 Hz, CHar), 120.0 (d, JCP = 12.6 Hz, CHar),
CHar), 134.0 (d, JCP = 10.0 Hz, CHar), 133.4–133.6 (m, CHar), 127.1 (d, JCP = 94.4 Hz, 2 C), 127.0 (d, JCP = 94.4 Hz, 3 C), 121.0
6
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Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I20407
/KAP1
Date: 24-07-12 10:40:52
Pages: 9
Bis-Ylide Ligands from Diphosphoniums
(q, JCF = 320.2 Hz, CF3SO3), 20.9 (d, JCP = 61.6 Hz, CH2), 5.6 (d,
JCP = 3.7 Hz, CH3), –6.3 (dd, JCPPh3 = 122.0, JCPPh2Et = 124.6 Hz,
= 89.0 Hz, 4 C), 8.66 (d, JCP = 57.7 Hz, 2 CH3) ppm. 31P NMR
(CDCl3, 25 °C): δ = +22.5 ppm. MS (ES+): m/z = 625.1 [M –
C) ppm. 31P NMR (CD2Cl2, 25 °C): δ = +24.2 (d, JPP = 24.3 Hz, OTf]+. HRMS (ES+): calcd. for C33H30O3F3P2S [M – OTf]+
PPh2Et), +19.3 (d, JPP = 24.3 Hz, PPh3) ppm. MS (ES+): m/z =
489.2 [M – OTf]+. HRMS (ES+): calcd. for C33H31P2 [M – OTf]+
489.1901; found 489.1901.
625.1370; found 625.1343.
Bis-Ylide 14: BuLi (2.5 m in hexane, 0.44 mmol, 180 μL) was added
to a solution of 13 (170 mg, 0.22 mmol) in [D8]thf (4.0 mL) at
–78 °C. Monitoring the reaction by low-temperature NMR allowed
the characterization of bis-ylide 14. 1H NMR ([D8]thf, –60 °C): δ
= 7.89 (s, 1 H, Har),7.85 (d, JHH = 10.0 Hz, 2 H, Har), 7.63 (d, JHH
= 10.0 Hz, 8 H, Har), 7.57 (t, JHH = 10.0 Hz, 1 H, Har), 7.52 (t,
JHH = 10.0 Hz, 4 H, Har), 7.44 (t, JHH = 10.0 Hz, 8 H, Har), 0.09
(d, JHP = 7.5 Hz, 4 H, CH2) ppm. 13C NMR ([D8]thf, –60 °C): δ =
Ylides 11c and 11e: BuLi (2.5 m in hexane, 160 μL, 0.40 mmol) was
added to a solution of 11 (160 mg, 0.20 mmol) in [D8]thf (5 mL)
cooled to –78 °C. Monitoring the reaction by low-temperature
NMR allowed the characterization of 11c. According to NMR
spectroscopy, 11c was then slowly converted into 11e. After evapo-
ration of the solvent, 11e was obtained as an yellow oil (107 mg,
82%). Recrystallization at room temperature in CH2Cl2 gave 11e
as colorless crystals.
135.4 (d, JCP = 20.3 Hz, 2 CHar), 135.1 (dd, JCP = 79.1, JCP
9.56 Hz, 2 C), 134.0 (d, JCP = 10.2, JCP = 2.4 Hz, 2 CHar), 133.4
(d, JCP = 86.8 Hz, 4 C), 132.0 (d, JCP = 10.1 Hz, 8 CHar), 130.9 (4
=
11c: 1H NMR ([D8]thf, –30 °C): δ = 7.84 (dd, JHP = JHH = 10.0 Hz,
2 H, Har), 7.80–7.74 (m, 2 H, Har), 7.65–7.49 (m, 9 H, Har), 7.38–
7.35 (m, 1 H, Har), 7.31–7.27 (m, 1 H, Har), 7.21 (t, JHH = 10.0 Hz,
1 H, Har), 7.15–7.05 (m, 4 H, Har), 6.90 (t, JHH = 10.0 Hz, 1 H,
Har), 6.81–6.76 (m, 2 H, Har), 6.23 (dd, JHP = JHH = 5.0 Hz, 1 H,
Har), 2.98–2.90 (m, 2 H, CH2), 1.22–1.08 (m, 3 H, CH3), 0.87 (br.
s, 3 H, CH3) ppm. 13C NMR ([D8]thf, –30 °C): δ = 174.2 (dd, JCP
= 28.9, JCP = 13.8 Hz, C), 163.2 (d, JCP = 12.6 Hz, C), 145.1 (d,
JCP = 125.8 Hz, C), 133.08 (d, JCP = 3.8 Hz, CHar), 132.76 (d, JCP
= 2.5 Hz, 2 CHar), 132.7 (d, JCP = 3.8 Hz, 2 CHar), 131.6 (d, JCP
= 2.5 Hz, CHar), 131.2–131.4 (3 CHar), 130.5 (d, JCP = 8.8 Hz,
CHar), 130.1 (CHar), 129.1 (CHar), 129.0 (d, JCP = 10.1 Hz, CHar),
128.7 (d, JCP = 11.3 Hz, CHar), 128.6 (d, JCP = 11.3 Hz, CHar),
127.0 (d, JCP = 10.1 Hz, CHar), 126.7 (d, JCP = 12.6 Hz, 2 CHar),
126.3 (CHar), 126.0 (d, JCP = 3.8 Hz, CHar), 125.9 (d, JCP = 3.8 Hz,
CHar), 124.2 (CHar), 120.7 (q, JCF = 320 Hz, CF3SO3), 29.0 (d, JCP
= 74.2 Hz, CH2), 12.6 (pseudo-t, JCP = JCP+ = 13.8 Hz, CH3), 9.5
(d, JCP = 6.3 Hz, CH3), 5.7 (dd, JCP+ = 120.0, JCP = 172.0 Hz,
C) ppm. 31P NMR ([D8]thf, –30 °C): δ = +10.1 (d, JPP = 94.2 Hz,
P+), –88.3 (d, JPP = 94.2 Hz, P) ppm.
CHar), 128.3 (d, JCP = 11.3 Hz, 8 CHar), 128.2 (C), –5.9 (d, JPC
=
98.1 Hz, CH2) ppm. 31P NMR ([D8]thf, –60 °C): δ = +19.6 ppm.
Rhodium Complex 15: A solution of [Rh(cod)2+][OTf–] (67 mg,
0.13 mmol) in thf was added to a solution of 14 (104 mg,
0.22 mmol) in thf (3.0 mL) at –70 °C and the suspension was then
stirred for 20 min. After warming to –30 °C, carbon monoxide was
bubbled through the solution for 10 min. After filtration, the sol-
vent was evaporated under vacuum. The remaining residue was
washed with pentane (5.0 mL) and then extracted with CH2Cl2
1
(5.0 mL) at 0 °C to afford 15 as an orange solid (83 mg, 60%). H
NMR (CD2Cl2, –10 °C): δ = 7.75–7.39 (m, 24 H, Har), 1.96 (br. d,
JHP = 10.0 Hz, 4 H, CH2) ppm. 13C NMR (CD2Cl2, –10 °C): δ =
186.3 (d, JCRh = 20.3 Hz, CO), 139.9 (br. s, C), 139.1 (br. s, C),
135.3 (CHar), 133.6 (CHar), 133.5–133.0 (m, CHar), 130.6–130.3 (m,
CHar), 129.4 (d, JCP = 12.6 Hz, CHar), 128.7 (d, JCP = 12.6 Hz,
CHar), 128.6 (CHar), 120.2 (q, JCF = 320.1 Hz, CF3SO3), 1.2 (dd,
JCP = 40.3, JCRh = 21.5 Hz, CH2) ppm. 31P NMR (CD2Cl2,
–10 °C): δ = +35.6 (br. s) ppm. 103Rh NMR (CD2Cl2, –10 °C): δ =
+477 ppm. MS (ES+): m/z = 633.1 [M]+. IR (CH Cl ): ν = 2053
˜
2
2
(CO), 1983 (CO) cm–1.
11e: 1H NMR (CD2Cl2, 25 °C): δ = 7.72–7.62 (m, 5 H, Har), 7.60–
7.50 (m, 20 H, Har), 2.09–2.00 (m, 2 H, CH2), 1.83 (pseudo-t,
JHPPh3 = JHPPh2Et = 15.0 Hz, 3 H, CH3), 1.07 (td, JHH = 5.0, JHP
= 20.0 Hz, 3 H, CH3) ppm. 13C NMR (CD2Cl2, 25 °C): δ = 134.1
(d, JCP = 10.1 Hz, CHar), 133.7 (d, JCP = 8.8 Hz, CHar), 133.4 (d,
JCP = 3.8 Hz, CHar), 133.0 (d, JCP = 2.5 Hz, CHar), 132.4 (d, JCP
Crystal Structure Determination of Compounds 10, 11, 11e, and 13
Intensity data were collected at low temperature on three different
diffractometers (Bruker Apex2, Bruker Apex2 Quazar, and Agilent
Gemini). Structures were solved by direct methods using SIR92[15]
and refined by full-matrix least-squares procedures using the pro-
grams of CRYSTALS[16] or WINGX.[17] Atomic scattering factors
were taken from the International Tables for X-ray Crystallogra-
phy.[18] All non-hydrogen atoms were refined anisotropically. Hy-
drogen atoms were refined by using a riding model. Absorption
= 8.8 Hz, CHar), 131.0 (d, JCP = 12.6 Hz, CHar), 129.5 (d, JCP
13.8 Hz, CHar), 129.4 (d, JCP = 13.8 Hz, CHar), 120.7 (q, JCF
320.4 Hz, CF3SO3), 20.7 (d, JCP = 60.4 Hz, CH2), 15.6 (t, JCP
=
=
=
3.8 Hz, CH3), 7.4 (d, JCP = 5.0 Hz, CH3), –2.0 (br. s, C) ppm. 31P
NMR (CD2Cl2, 25 °C): δ = +28.83 (d, JPP = 53.7 Hz, PPh2Et),
+25.39 (d, JPP = 53.7 Hz, PPh3) ppm. MS (ES+): m/z = 503.2 [M]+.
HRMS (ES+): calcd. for C34H33P2 [M]+ 503.2071; found 503.2057.
corrections were introduced by using the
program
MULTISCAN.[19]
Crystal Data for 10: C33H32P2·2(CF3O3S)·C4H8O,
M
=
860.81 gmol–1, monoclinic, a = 10.4034(3), b = 8.9863(2), c =
21.4353(6) Å, β = 97.0880(10)°, V = 1988.63(9) Å3, T = 180 K,
space group Pc, Z = 2, μ(Mo-Kα) = 0.291 mm–1, 57469 reflections
measured, 14843 unique (Rint = 0.029), 11497 reflections used in
Diphosphonium 13: Methyl trifluoromethanesulfonate (1.60 mL,
14.50 mmol) was added to a solution of 12 (2.98 g, 6.59 mmol) in
CH2Cl2 (75.0 mL) at –50 °C. The suspension was then warmed to
room temperature and stirred for 2 h. After evaporation of the sol-
vent, the crude residue was washed with Et2O (30 mL) to afford 13
as a white solid (4.33 g, 86%). Recrystallization at –20 °C from
the calculations [IϾ3σ(I)], 506 parameters, R = 0.0419, wR2
0.0460, Flack parameter: 0.02(4).
=
1
CH2Cl2/pentane gave 13 as colorless crystals; m.p. 160–163 °C. H
Crystal Data for 11: C34H34P2·2(CF3O3S)·CH2Cl2,
M
=
NMR (CDCl3, 25 °C): δ = 7.94–7.90 (m, 2 H, Har), 7.89–7.85 (m,
1 H, Har), 7.84–7.80 (m, 8 H, Har), 7.77–7.72 (m, 4 H, Har), 7.68–
7.62 (m, 9 H, Har), 2.95 (d, JHH = 13.8 Hz, 6 H, CH3) ppm. 13C
887.64 gmol–1, monoclinic, a = 9.6404(9), b = 16.7750(15), c =
25.213(2) Å, β = 103.792(5)°, V = 3959.8(6) Å3, T = 193 K, space
group P21/c, Z = 4, μ(Mo-Kα) = 0.423 mm–1, 29237 reflections
measured, 7216 unique (Rint = 0.044), 5094 reflections used in the
calculations [IϾ2σ(I)], 605 parameters, R = 0.0541, wR2 = 0.1278.
NMR (CDCl3, 25 °C): δ = 139.3 (pseudo-t, JCP = 12.2, JCP
=
12.5 Hz, CHar), 138.3 (dd, JCP = 3.9, JCP = 11.5 Hz, CHar), 135.2
(4 CHar), 133.6 (d, JCP = 11.4 Hz, CHar), 131.2 (t, JCP = 12.4 Hz,
CHar), 130.4 (d, JCP = 13.7 Hz, 8 CHar), 122.9 (dd, JCP = 13.2, JCP
Crystal Data for 11e: C34H33P2·CF3O3S, M = 652.65 gmol–1, tri-
= 89.9 Hz, 2 C), 120.6 (q, JCF = 320.2 Hz, CF3SO3), 118.0 (d, JCP clinic, a = 9.9459(2), b = 11.2494(3), c = 15.1467(4) Å, α =
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
7

Job/Unit: I20407
/KAP1
Date: 24-07-12 10:40:52
Pages: 9
Y. Canac, R. Chauvin et al.
FULL PAPER
72.500(2), β = 89.6428(19), γ = 79.3817(19)°, V = 1586.40(7) Å3, T
= 180 K, space group P1, Z = 2, μ(Cu-Kα) = 2.308 mm , 29049
reflections measured, 4780 unique (Rint = 0.027), 4619 reflections
used in the calculations [IϾ3σ(I)], 452 parameters, R = 0.0353,
wR2 = 0.0468.
R. Chauvin, Inorg. Chem. 2009, 48, 2147; d) E. Serrano, C.
Vallés, J. J. Carbó, A. Lledós, T. Soler, R. Navarro, E. P. Urriol-
abeitia, Organometallics 2006, 25, 4653; e) A. Spannenberg, W.
Baumann, U. Rosenthal, Organometallics 2000, 19, 3991.
[3] M. Abdalilah, Y. Canac, C. Lepetit, R. Chauvin, C. R. Chim.
2010, 13, 1091, and references cited therein.
–1
¯
Crystal Data for 13: C32H30P2·2(CF3O3S), M = 774.64 gmol–1, mo-
noclinic, a = 15.479(5), b = 13.374(5), c = 19.291(5) Å, β =
106.112(5)°, V = 3837(2) Å3, T = 180 K, space group P21/n, Z =
4, μ(Mo-Kα) = 0.292 mm–1, 42662 reflections measured, 9493
unique (Rint = 0.054), 5777 reflections used in the calculations
[IϾ2σ(I)], 453 parameters, R = 0.0553, wR2 = 0.1341.
[4] M. Abdalilah, R. Zurawinski, Y. Canac, B. Laleu, J. Lacour,
C. Lepetit, G. Magro, G. Bernardelli, B. Donnadieu, C. Du-
hayon, M. Mikolajczyk, R. Chauvin, Dalton Trans. 2009, 8493.
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[9] CCDC-876380 (for 10), -876378 (for 11), -876377 (for 11e),
and -876379 (for 13) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[10] a) H. Schmidbaur, O. Gasser, M. Sakhawat Hussain, Chem.
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Acknowledgments
In addition to the Ministère de l’Enseignement Supérieur de la Re-
cherche et de la Technologie, the Université Paul Sabatier, and the
Centre National de la Recherche Scientifique (CNRS), thanks are
due to the Agence Nationale de la Recherche (ANR) program
(ANR-08-JCJC-0137-01) for a doctoral fellowship to C. M. Laure
Vendier and Sonia Ladeira for X-ray structure determination and
Christian Bijani for NMR measurements are also gratefully ac-
knowledged. The authors also thank one of the referees for a rel-
evant suggestion in the analysis of the steric strain in the diphos-
phoniums 5, 10, and 11.
[13] Y. Canac, C. Maaliki, I. Abdellah, R. Chauvin, New J. Chem.
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[1] a) E. P. Urriolabeitia, Top. Organomet. Chem. 2010, 30, 15; b)
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Kolodiazhnyi, Tetrahedron 1996, 52, 1855; f) W. C. Kaska,
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[17] Integrated system of Windows programs for the solution, re-
finement, and analysis of single-crystal X-ray diffraction data:
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[2] For recent examples, see: a) N. Dellus, T. Kato, N. Saffon-Mer-
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Received: April 21, 2012
Published Online: ᭿
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Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I20407
/KAP1
Date: 24-07-12 10:40:52
Pages: 9
Bis-Ylide Ligands from Diphosphoniums
Bis-Ylide Ligands
C. Maaliki, M. Abdalilah, C. Barthes,
C. Duhayon, Y. Canac,*
R. Chauvin* ...................................... 1–9
Bis-Ylide Ligands from Acyclic Proximal
Diphosphonium Precursors
Although disubstituted o-phenylene-di-
phosphonium bis-ylides cannot be gener-
ated by double deprotonation, a m-phenyl-
ene isomer could and was used as a chelat-
ing electron-rich C2 ligand in a rhodium(I)
complex.
Keywords: Ylides / Ylide ligands / Phos-
phorus / Rhodium / Electrostatic interac-
tions
Eur. J. Inorg. Chem. 0000, 0–0
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