From functional phospholide ions to bifunctional 1,1′- diphosphaferrocenes

Article abstract of DOI:10.1021/om7012474

Both the 2-ethoxycarbonyl and the 2-benzoyl phospholides (1 and 2) react with FeCl₂ in the presence of ZnCl₂ to give the corresponding 2,2′-difunctional 1,1′-diphosphaferrocenes as mixtures of meso and rac diastereomers. Stable rotamers are also detected by ¹H and ¹³C NMR spectroscopy. Under the same conditions, the 2,5-bis(ethoxycarbonyl)phospholide (3) gives the tetrafunctional 1,1′-biphospholyl (6). The diphosphaferrocenes and the 1,1′-biphospholyl are probably formed from a common type of intermediates with a bis(η¹-phospholyl)iron structure. DFT computations indicate that this kind of intermediate is pyramidal at P and only weakly aromatic.

Full text of DOI:10.1021/om7012474

Organometallics 2008, 27, 1887–1891
1887
From Functional Phospholide Ions to Bifunctional
1,1′-Diphosphaferrocenes
Aholibama Escobar, Bruno Donnadieu, and François Mathey*
UCR-CNRS Joint Research Chemistry Laboratory, Department of Chemistry, UniVersity of California
RiVerside, RiVerside, California 92521-0403
ReceiVed December 13, 2007
Both the 2-ethoxycarbonyl and the 2-benzoyl phospholides (1 and 2) react with FeCl2 in the presence
of ZnCl2 to give the corresponding 2,2′-difunctional 1,1′-diphosphaferrocenes as mixtures of meso and
rac diastereomers. Stable rotamers are also detected by 1H and 13C NMR spectroscopy. Under the same
conditions, the 2,5-bis(ethoxycarbonyl)phospholide (3) gives the tetrafunctional 1,1′-biphospholyl (6).
The diphosphaferrocenes and the 1,1′-biphospholyl are probably formed from a common type of
intermediates with a bis(η1-phospholyl)iron structure. DFT computations indicate that this kind of
intermediate is pyramidal at P and only weakly aromatic.
easy access to difunctional phosphaferrocenes. Aside from silyl-
substituted derivatives,7 the only described difunctional deriva-
tive is a 2,2′-diacetyl-1,1′-diphosphaferrocene obtained by
Friedel–Crafts acetylation of a nonfunctional diphosphafer-
rocene.2 Some time ago, we devised a synthesis of functional
phospholide ions based on the [1,5] shift of the functional group
from P to CR (eq 1).8
Introduction
Together with phosphinines (A), phosphaferrocenes (B) and
1,1′-diphosphaferrocenes (C) are certainly the most accessible
and representative species incorporating a sp2-phosphorus center
into an aromatic system. In all of these cases, the parent species
are isolable1,2 because the aromatic stabilization energy elimi-
nates the need for kinetic stabilization by bulky substituents,
as is the case for phosphaalkenes. This situation is exceptionally
favorable since it has been demonstrated that bulky substituents
significantly alter the chemistry of low-coordinate phosphorus
centers.3
(1)
The simplicity of this one-pot synthesis of functional phos-
pholides is quite attractive, and it was tempting to investigate
their reaction with iron(II) derivatives in order to get bifunctional
phosphaferrocenes. In this context, we were intrigued by a report
of Ganter et al.7 stating that they had been unable to convert
2,5-difunctional phospholide ions into the corresponding Fe or
Ru sandwich complexes. We thus decided to investigate this
reaction more closely.
Phosphaferrocenes have already found interesting applications
as ligands for transition metals in homogeneous catalysis.4 A
logical further development of their chemistry would be to
incorporate them into macrocyclic structures. The phosphinine
ring has indeed been incorporated into macrocyclic structures,5
and the resulting macrocycles have shown an exceptional ability
to stabilize low oxidation state metallic centers.6 A prerequisite
for the synthesis of phosphaferrocene-based macrocycles is an
Results and Discussion
This work being focused on carbonyl functionalities, we first
decided to investigate the influence of a carbonyl substituent
on the electronic structure of a phospholide ion. A comparative
theoretical study was carried out on the parent phospholide (D),
the 2-formylphospholide (E), and the 2,5-diformylphospholide
(F) by DFT at the B3LYP/6-311G++(3df,2p) level.9 The
counterion was not included since it has been shown previously
that it has only a limited influence on the structure of the anion.10
the results are collected in Table 1. Grafting one or two
carbonyls on the ring significantly alters its structure. Anions
(1) Ashe, A. J., III J. Am. Chem. Soc. 1971, 93, 3293.
(2) De Lauzon, G.; Deschamps, B.; Fischer, J.; Mathey, F.; Mitschler,
A. J. Am. Chem. Soc. 1980, 102, 994.
(3) Nyulaszi, L. J. Organomet. Chem. 2005, 690, 2597.
(4) (a) Qiao, S.; Fu, G. C. J. Org. Chem. 1998, 63, 4168. (b) Tanaka,
K.; Qiao, S.; Tobisu, M.; Lo, M. M.-C.; Fu, G. C. J. Am. Chem. Soc. 2000,
122, 9870. (c) Shintani, R.; Fu, G. C. J. Am. Chem. Soc. 2003, 125, 10778.
(d) Ogasawara, M.; Yoshida, K.; Hayashi, T. Organometallics 2001, 20,
3913. (e) Suarez, A.; Downey, C. W.; Fu, G. C. J. Am. Chem. Soc. 2005,
127, 11244. (f) Ogasawara, M.; Ito, A.; Yoshida, K.; Hayashi, T.
Organometallics 2006, 25, 2715.
(5) (a) Avarvari, N.; Mézailles, N.; Ricard, L.; Le Floch, P.; Mathey, F.
Science 1998, 280, 1587. (b) Avarvari, N.; Maigrot, N.; Ricard, L.; Mathey,
F.; Le Floch, P. Chem.-Eur. J. 1999, 5, 2109.
(7) (a) Sava, X.; Mézailles, N.; Maigrot, N.; Nief, F.; Ricard, L.; Mathey,
F.; Le Floch, P. Organometallics 1999, 18, 4205. (b) Loschen, R.; Loschen,
C.; Frank, W.; Ganter, C. Eur. J. Inorg. Chem. 2007, 553.
(8) (a) Holand, S.; Jeanjean, M.; Mathey, F. Angew. Chem., Int. Ed.
Engl. 1997, 36, 98. (b) Review: Mathey, F. Acc. Chem. Res. 2004, 37,
954.
(6) Mézailles, N.; Avarvari, N.; Maigrot, N.; Ricard, L.; Mathey, F.;
Le Floch, P.; Cataldo, L.; Berclaz, T.; Geoffroy, M. Angew. Chem., Int.
Ed. 1999, 38, 3194.
10.1021/om7012474 CCC: $40.75
2008 American Chemical Society
Publication on Web 03/25/2008

1888 Organometallics, Vol. 27, No. 8, 2008
Escobar et al.
Table 1. Computed Data on Phospholides
b
aRHF/6-311+G**; see ref 11. Mulliken.
Figure 1. Highest occupied orbitals of anion F.
E and F are better represented by the mesomeric formulations
shown in eq (2).
For our experimental work, we chose to investigate the
reaction of the three easily accessible functional phospholides
1-38,12 with FeCl2. Our initial experiments were carried out
with 1.
(2)
The reaction of 1 with FeCl2 in THF at RT afforded only a
complex mixture of decomposition products. We suspected that
Fe(II) was partly reduced by the anion, and we chose to reduce
the ionicity of the potassium phospholide by metathesis with
ZnCl2. The zinc phospholide cleanly reacted with FeCl2 to give
a 70:30 mixture of the expected meso (4a)(δ31P -45.9 ppm)
and rac (4b)(δ31P -50.5 ppm) difunctional 1,1′-diphosphafer-
rocenes (eq 3).
The negative charge at P sharply decreases from D to E and
F, but the aromaticity does not according to the NICS(1) index.
The highest occupied orbitals are shown in Figure 1 for F. The
HOMO and HOMO-1 that are involved in the π-bonding with
Fe(II) are shifted to lower energies to such an extent that πasym
is lower for F than the lone pair orbital for D. This cast some
doubt on the ability of F to give a stable π-complex with iron.
Indeed, the energetic gap between these orbitals and the dxz and
dyz orbitals of iron might become too large to allow the formation
of a stable η5-structure.
(9) , Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery., J. A., Jr.; Vreven, T.; Kudin, K. N.;
Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.;
Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels,
A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.;
Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz,
P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson,
B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03,
Revision B.05; Gaussian, Inc., Pittsburgh, PA, 2003.
(3)
After a preliminary purification by chromatography, the pure
meso diastereomer was obtained in the pure state by extraction
with pentane. The X-ray crystal structure of 4a is shown in
Figure 2. The two phospholyl rings are in a head-to-tail
disposition. The carbonyls are lying in the planes of the rings
1
(10) Grundy, J.; Donnadieu, B.; Mathey, F. J. Am. Chem. Soc. 2006,
128, 7716.
and are directed toward the methyl substituents. The H NMR
(11) Chen, Z.; Wannere, C. S.; Corminboeuf, C.; Puchta, R.; Schleyer,
P. v. R. Chem. ReV. 2005, 105, 3842.
(12) Toullec, P.; Mathey, F. Synlett 2001, 1977.

Functional Phospholide Ions
Organometallics, Vol. 27, No. 8, 2008 1889
Figure 2. X-ray crystal structure of meso-2,2′-bis(ethoxycarbonyl)-
1,1′-diphosphaferrocene (4a). Ellipsoids are scaled to enclose 50%
of the electronic density. Main bond lengths (Å) and angles (deg):
P1–C1 1.87(5), P1-C4 1.76(5), C1-C2 1.451(16), C2-C3
1.407(18), C3-C4 1.374(18), Fe1-C1 2.11(5), Fe1-C4 2.04(3),
Fe1-P1 2.221(38); C1-P1-C4 86(2).
Figure 3. X-ray crystal structure of 3,3′,4,4′-tetramethyl-2,2′,5,5′-
tetrakis(ethoxycarbonyl)-1,1′-biphospholyl (6). Ellipsoids are scaled
to enclose 50% of the electronic density. Main bond lengths (Å)
and angles (deg): P1-P1′ 2.2289(14), P1-C1 1.809(2), P1-C4
1.805(4), C1-C2 1.358(4), C2-C3 1.466(4), C3-C4 1.362(3);
C1-P1-C4 89.66(11), C1-P1-P1′ 98.29(9), C4-P1-P1′
102.95(8).
spectrum shows two types of ethyl groups whose methyl
resonances appear at 0.88 (37%) and 1.05 ppm (63%). These
methyl resonances are correlated with two closely spaced 13C
resonances at 14.31 (minor) and 14.41 ppm (major). Two sets
f η5 fluctuation would yield the diphosphaferrocene, whereas
a reductive elimination would yield the 1,1′-biphospholyl.
1
of OCH2 resonances also appear on the H spectrum, but they
are very close. We interpret this phenomenon as resulting from
the presence of two stable rotamers. In the minor one, the
carbonyls would lie opposite of the methyl substituents. Upon
heating at 60–70 °C, the minor rotamer is slowly and irreversibly
transformed into the major one. We prefer this explanation
rather than the other possibility involving a blocked rotation
around the Fe axis because only the ethyl resonances are
different in the two rotamers.
Using the same experimental protocol, we were able to
prepare the 2,2′-dibenzoyl-1,1′-diphosphaferrocene (5) from the
functional phospholide 2. Like 4, 5 is obtained as a mixture of
meso (5a) and rac (5b) diastereomers.
(4)
In order to give some support to this proposition, we decided
to compute the structure of 7 with two molecules of THF as
additional ligands. The computation was carried out by DFT at
the B3LYP/6-31G(d) (C, H, O, P) and lanl2dz (Fe) level. The
computed structure is shown in Figure 4. It corresponds to a
genuine minimum (no negative frequency). The most interesting
feature is that the phosphorus atoms are pyramidal (∑angles at
P ) 336.9°), although less than in a normal phosphole. As a
result, the phosphole ring is poorly delocalized and a strong
alternation between the single and the double bonds is still
present (1.443 vs 1.370 Å). We note a good agreement with
the X-ray crystal structure analysis of a η1-phospholyltungsten
complex.13 One of the driving forces for the formation of the
diphosphaferrocene is thus the aromatization of the rings during
the η1 f η5 fluctuation. Such a driving force does not exist in
the case of pyrrolyl complexes (both η1- and η5-pyrrolyl
complexes are aromatic), and this might explain why diazafer-
rocenes are more difficult to prepare than diphosphaferrocenes.14
1
The H and 13C NMR spectra show that 5b is a mixture of
two rotamers.
Always using the same protocol, the reaction of the difunc-
tional phospholide 3 with FeCl2 yielded the tetrafunctional
biphospholyl 6 in 20% overall yield. Due to the paramagnetism
of the solution, it proved impossible to monitor the reaction by
31P NMR. However, after filtration on silica gel, we checked
that 6 was the sole important product and that no diphospha-
ferrocene was formed. Obviously, the modest overall yield partly
reflects the moderate yield of the functionalization step. The
X-ray crystal structure of 6 is shown in Figure 3. The P-P
distance is normal at 2.2289(14) Å. The two rings are in a
staggered conformation. The phosphorus atoms are highly
pyramidal; ∑angles at P ) 290.9°. The strong alternation
between the C-C single and the CdC double bonds of the rings
confirms the absence of electronic delocalization. The carbonyls
are directed toward the methyl substituents but are not coplanar
with the rings.
Experimental Section
Nuclear magnetic resonance spectra were obtained on Bruker
Avance 300 and Varian Inova spectrometers operating at 300.13
MHz for H, 75.45 MHz for 13C, and 121.496 MHz for 31P. A
1
Bruker Avance 600 instrument was also used for 1H and 13C
(150.925 MHz) spectra. Chemical shifts are expressed in parts per
(13) Mercier, F.; Ricard, L.; Mathey, F. Organometallics 1993, 12, 98.
(14) Kuhn, N.; Horn, E. M.; Boese, R.; Augart, N. Angew. Chem., Int.
Ed. Engl. 1988, 27, 1368.
These results suggest that the reaction of phospholides with
FeCl2 proceeds via a σ P-Fe complex such as 7 (eq 4). A η1

1890 Organometallics, Vol. 27, No. 8, 2008
Escobar et al.
tBuOK (1.3 g, 11.7 mmol) was added at 0 °C, and the solution
was stirred at 60 °C for 2 h. The solution was cooled to 0 °C,
ZnCl2 (1.4 g, 10.63 mmol) was added, and the mixture was stirred
at room temperature for 30 min. FeCl2 (0.67 g, 5.3 mmol) was
added, and the solution was stirred for 18 h. The crude reaction
mixture was filtered through silica and concentrated. Purification
was performed via column chromatography on silica using 3:2
petroleum ether/dichloromethane solution. A red band was collected
and, once concentrated, 863 mg of a red oil was obtained (33%
yield). The two diastereomers were separated by a second chro-
matography with methylene chloride as the eluent and crystallized
upon slow evaporation of the solvent.
1
meso Diastereomer (5a). 31P NMR (C6D6): δ –53.1. H NMR
(C6D6): δ 1.88 (s, Me), 2.10 (s, Me), 3.93 (m, CH-P), 6.98 – 7.16
(m, Ph), 7.86 (m, Ph ortho). 13C NMR (C6D6): δ 11.40 (s, Me),
12.60 (s, Me), 83.68 (m, dCH-P), 91.34 (m, dC-P), 98.93 (d,
dC(Me)), 101.70 (d, dC(Me)), 139.26 (s, Ph ipsoC), 197.68
(pseudo t, CO).
rac Diastereomers (5b1 and 5b2): 5b1 (major). 31P NMR
1
(C6D6): δ –43.7. H NMR (C6D6): δ 1.87 (s, Me), 2.09 (s, Me),
4.09 (d, 2JHP ) 45 Hz, CH-P), 7.84 (m, Ph ortho). 13C NMR (C6D6):
Figure 4. Computed structure of the σ-complex (7)(THF)2. Main
bond lengths (Å) and angles (deg): Fe-P9 2.278, P9-C1 1.791,
P9-C4 1.792, C1-C2 1.369, C2-C3 1.443, C3-C4 1.370, Fe-P45
2.253; P9-Fe-P45 103.84, C1-P9-C4 91.08, C1-P9-Fe 115.35,
C4-P9-Fe 130.44.
δ 13.14 (s, Me), 14.37 (s, Me), 87.69 (d, 1JCP ) 74.7 Hz, dCH-P),
1
96.68 (d, JCP ) 79.7 Hz, dC-P), 100.66 (s, dC(Me)), 103.45
(d, 2JCP ) 5.0 Hz, dC(Me)), 141.14 (s, Ph ipsoC), 199.04 (d, 2JCP
) 22.3 Hz, CO).
1
5b2 (minor). 31P NMR (C6D6): δ –43.4. H NMR (C6D6): δ
million downfield from external TMS (1H and 13C) and external
85% H3PO4 (31P). Mass spectra were obtained on VG 7070 and
Hewlett-Packard 5989A GC/MS spectrometers. Elemental analyses
were performed by Desert Analytics Laboratory, Tucson, AZ.
3,3′,4,4′-Tetramethyl-2,2′-bis(ethoxycarbonyl)-1,1′-diphospha-
ferrocene (4a,b). 1-Phenyl-3,4-dimethylphosphole (2 g, 10.63
mmol) in dry THF (25 mL) was allowed to react with an excess of
lithium wire until the P-Ph bond cleavage was completed. After
excess lithium was removed, the solution was treated with tert-
butyl chloride (1.2 mL, 10.63 mmol) and heated to 60 °C for 1 h.
Ethyl chloroformate (1.1 mL, 11.7 mmol) was added dropwise at
-78 °C. The solution was heated at 65 °C for 2.5 h. tBuOK was
added (1.3 g, 11.7mmol) at 0 °C. The resulting mixture was heated
at 60 °C for 2 h. ZnCl2 (1.4 g, 10.63 mmol) was added at 0 °C and
stirred at room temperature for 30 min. FeCl2 (0.67 g, 5.3 mmol)
was added at room temperature. The solution was stirred for 18 h
at RT. The crude solution mixture was filtered through silica and
concentrated. Purification was performed via column chromatog-
raphy on silica using 3:2 dichloromethane/ petroleum ether. A red
band was collected and, once concentrated, 683 mg of a red solid
was obtained (30% yield). The meso diastereomer was extracted
from the solid with pentane and crystallized from the pentane
solution. We were unable to get the rac diastereomer in the pure
form.
2.07 (s, Me), 2.26 (s, Me), 3.92 (m, CH-P), 7.80 (m, Ph ortho).
13C NMR (C6D6): δ 15.39 (s, Me), 16.49 (s, Me), 85.31 (m,
2
dCH-P), 93.09 (m, dC-P), 99.90 (d, JCP ) 5.0 Hz, dC(Me)),
102.57 (d, 2JCP ) 10.0 Hz, dC(Me)), 141.01 (s, Ph ipsoC), 199.44
(pseudo t, CO). Anal. Calcd for C26H24FeO2P2: C, 64.22; H, 4.97.
Found: C, 64.39; H, 4.94.
3,3′,4,4′-Tetramethyl-2,2′,5,5′-tetrakis(ethoxycarbonyl)-1,1′-
biphospholyl (6). 1-Phenyl-3,4-dimethylphosphole (2 g, 10.63
mmol) in dry THF (25 mL) was allowed to react with an excess of
lithium wire until the P-Ph bond cleavage was complete. After
excess lithium was removed, the solution was treated with tert-
butyl chloride (1.2 mL, 10.63 mmol) and heated to 60 °C for 1 h.
Ethyl chloroformate (1.1 mL, 11.7 mmol) was added dropwise at
-78 °C. The solution was heated at 65 °C for 2.5 h. tBuOK was
added (1.4 g, 12.8 mmol) at 0 °C, followed by heating at 60 °C for
2 h. A second equivalent of ethyl chloroformate (1.2 mL, 12.8
mmol) was added at -78 °C, immediately followed by addition of
a second equivalent of tBuOK (1.4 g, 12.8 mmol) at 0 °C. The
resulting mixture was stirred at 40 °C for 18 h. The solution was
cooled to 0 °C, ZnCl2 (1.4 g, 10.63 mmol) was added, and the
mixture was stirred at room temperature for 30 min. FeCl2 (0.67 g,
5.3 mmol) was added, and the mixture was stirred for 18 h. The
crude reaction mixture was filtered through silica and concentrated.
Purification was performed via column chromatography on silica
using 100:1 dichloromethane/ethyl acetate solution. A yellow band
was collected and, once concentrated, 542 mg of a yellow solid
was obtained (20% yield). The yellow solid was recrystallized from
dichloromethane.
31P NMR (CD2Cl2): δ –6.5. 1H NMR (CD2Cl2): δ 1.29 (t,
Me(Et)), 2.34 (m, Me-Cd), 4.07 (m, OCH2), 4.20 (m, OCH2).
13C NMR (CD2Cl2): δ 14.57 (s, Me(Et)), 15.82 (s, Me-Cd), 61.18
(s, OCH2), 136.32 (pseudo t, CR), 158.12 (pseudo t, Cꢀ), 165.00
(pseudo t, CO). MS (EI): m/z 510 (M, 80%), 254 (M/2, 100%).
The compound is sensitive to oxidation. Anal. Calcd for
C24H32O8P2: C, 56.47; H, 6.32. Found: C, 56.2; H, 6.3.
X-Ray Structure Determination of 4a and 6. Compounds were
measured at low temperature, T ) 100(2) K, on a X8-APEX Bruker
Kappa four-circle X-ray diffractometer system (Mo radiation, λ )
0.71073 Å). An optimized data collection strategy was defined using
1
meso Diastereomer (4a). 31P NMR (C6D6): δ –45.3. H NMR
(C6D6): δ 0.88 (t, Me(Et) minor), 1.05 (t, Me(Et) major), 1.78 (s,
Me), 2.40 (s, Me), 3.72 (d, 2JHP ) 36.4 Hz, CH-P), 4.04 (2q, OCH2).
13C NMR (C6D6): δ 13.54 (s, Me), 14.41 (s, Me(Et)), 15.17 (s,
1
Me), 60.30 (s, OCH2), 84.40 (d, JC-P ) 62.3 Hz, dC-P), 86.45
(d, 1JC-P ) 58.7 Hz, dCH-P), 98.74 (d, 2JCP ) 5.2 Hz, dC(Me)),
2
2
102.64 (d, JCP ) 9.0 Hz, dC(Me)), 171.32 (d, JCP ) 19.8 Hz,
CO). MS (EI): m/z 422 (M+, 100%). Anal. Calcd for C18H24FeO4P2:
C, 51.21; H, 5.73. Found: C, 50.79; H, 5.79.
3,3′,4,4′-Tetramethyl-2,2′-dibenzoyl-1,1′-diphosphafer-
rocene (5a,b). 1-Phenyl-3,4-dimethylphosphole (2 g, 10.63 mmol)
in dry THF (25 mL) was allowed to react with an excess of lithium
wire until the P-Ph bond cleavage was completed. After excess
lithium was removed, the solution was treated with tert-butyl
chloride (1.2 mL, 10.63 mmol) and heated at 60 °C for 1 h. Benzoyl
chloride (1.4 mL, 11.7 mmol) was added dropwise at -78 °C. The
mixture was warmed to room temperature and stirred for 20 min.

Functional Phospholide Ions
Organometallics, Vol. 27, No. 8, 2008 1891
Cosmo.15 Frames were integrated with the aid of Bruker Saint
software16 included in the Bruker APEX2 package17 and using a
narrow-frame integration algorithm.
determination and structure solution, followed by some subsequent
differences Fourier maps. From the primary electron density map
most of the non-hydrogen atoms were located, and with the aid of
subsequent isotropic refinement all of the non-hydrogen atoms were
identified. Atomic coordinates and isotropic and anisotropic dis-
placement parameters of all the non-hydrogen atoms were refined
by means of a full matrix least-squares procedure on F2. The H
atoms were included in the refinement in calculated positions riding
on the C atoms to which they were attached. The refinement
converged for 4a at R1 ) 0.0751, wR2 ) 0.1862, with intensity I
> 2σ(I), and for 6 at R1 ) 0.0406, wR2 ) 0.1057 with intensity
I > 2σ(I).
4a: The integrated frames yielded a total of 3925 reflections at
a maximum 2θ angle of 43.94°, of which 1127 were independent
reflections (Rint ) 0.0814, Rsig ) 0.0895, completeness ) 98.5%)
and 871 (77.28%) reflections were greater than 2σ(I). A triclinic
cell space group P2(1)/n was found; the unit cell parameters were
a ) 6.796(5) Å, b ) 8.163(6) Å, c ) 16.939(13) Å, R ) 90.0°, ꢀ
) 96.360(9)°, γ ) 90.0°, V ) 933.9(12) Å3, Z ) 4, calculated
density Dc ) 1.473 Mg/m3. The molecule is statistically disordered
on two positions.
6: The integrated frames yielded a total of 6858 reflections at a
maximum 2θ angle of 46.50°, of which 1835 were independent
reflections (Rint ) 0.0307, Rsig ) 0.0294, completeness ) 99.4%)
and 1617 (88.12%) reflections were greater than 2σ(I). A monoclinic
cell space group C2/c was found; the unit cell parameters were a
) 20.816(5) Å, b ) 10.489(2) Å, c ) 12.513(3) Å, ꢀ )
109.335(3)°, V ) 2578.2(10) Å3, Z ) 8, calculated density Dc )
1.315 Mg/m3.
Drawings of molecules were performed using ORTEP32.20
(Further details on the Crystal Structure Investigation are available
on request from the Director of the Cambridge Crystallographic
Data Centre, 12 Union Road, GB-Cambridge CB21EZ UK, on
quoting the full journal citation.)
Acknowledgment. The authors thank the University of
California Riverside and the CNRS (Paris) for financial
support.
6 is organized around a C2 axis with the following symmetry
transformations used to generate equivalent atoms: #1 -x,y,-z+3/2.
Absorption corrections were applied for data using the SAD-
ABS18 program. The program SIR9219 was used for phase
Supporting Information Available: X-ray crystal structure
analyses of compounds 4a and 6. This material is available free of
charge via the Internet at http://pubs.acs.org.
(15) COSMO Version 1.53; Bruker AXS Inc.: Madison, WI, 2004.
(16) SAINT Version V7.06A; Bruker AXS Inc.: Madison, WI, 2003.
(17) APEX 2 Version 2.0–2; Bruker AXS Inc.: Madison, WI, 2004.
(18) SADABS Version 2004/1; Bruker AXS Inc.: Madison, WI, 2004.
(19) SIR92-A program for crystal structure solution. Altomare, A.;
Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl. Crystallogr. 1993,
26, 343–350.
OM7012474
(20) ORTEP3 for Windows. Farrugia, L. J. J. Appl. Crystallogr. 1997,
30, 565.