Synthesis, properties and structures of methyldiphenylphosphonium 1-indenylide, 1-C9H6PMePh2, and its chiral tricarbonylchromium(0) complex Cr(η5-1-C9H6PMePh2)(CO)3

Article abstract of DOI:10.1016/j.jorganchem.2008.05.027

The hitherto unknown indenyl-derived ylide, methyldiphenylphosphonium 1-indenylide, 1-C₉H₆PMePh₂ (1) and its chromium(0) complex, Cr(η⁵-1-C₉H₆PMePh₂)(CO)₃ (2) have been synthesized and characterized spectroscopically and crystallographically. The structures and properties of 1 and 2 are compared with those of the analogous C₅H₄PMePh₂ and its chromium complex, Cr(η⁵-C₅H₄PMePh₂)(CO)₃. Compound 2, obtained as a racemic mixture, exhibits planar chirality resulting from coordination of the prochiral aromatic ligand.

Full text of DOI:10.1016/j.jorganchem.2008.05.027

Journal of Organometallic Chemistry 693 (2008) 2812–2817
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Note
Synthesis, properties and structures of methyldiphenylphosphonium
1-indenylide, 1-C9H6PMePh2, and its chiral tricarbonylchromium(0)
complex Cr(
g
5-1-C9H6PMePh2)(CO)3
*
John H. Brownie, Michael C. Baird
Department of Chemistry, Queen’s University, Kingston, Ontario, Canada K7L 3N6
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 May 2008
Received in revised form 19 May 2008
Accepted 19 May 2008
Available online 24 May 2008
The hitherto unknown indenyl-derived ylide, methyldiphenylphosphonium 1-indenylide, 1-C9H6PMePh2
(1) and its chromium(0) complex, Cr(
ized spectroscopically and crystallographically. The structures and properties of 1 and 2 are compared
with those of the analogous C5H4PMePh2 and its chromium complex, Cr(
5-C5H4PMePh2)(CO)3. Com-
g
5-1-C9H6PMePh2)(CO)3 (2) have been synthesized and character-
g
pound 2, obtained as a racemic mixture, exhibits planar chirality resulting from coordination of the pro-
chiral aromatic ligand.
Keywords:
Ó 2008 Elsevier B.V. All rights reserved.
Chromium
Ylide
Planar chirality
Phosphonium 1-indenylides
1. Introduction
ylide carbon and a P–C(ylide) coupling constant typical of an ali-
phatic carbon–P bond [2h]. Our recent report [1] has shown that
We have recently reported on the synthesis and reactivity of the
group 6 compounds M(
5-C5H4PMePh2)(CO)3 (M = Cr, Mo, W),
C5H4PMePh2 has properties similar to those of C5H4PPh3.
g
One of the notable problems that may have limited the explora-
tion of this class of ligand is the lack of a general synthetic route,
since the original Ramirez synthetic procedure [2] appears not to
be generally applicable to other phosphine systems [3]. In an at-
tempt to extend the chemistry of this class of ligand, we have be-
gun an investigation into the use of the indenyl-derived ylide,
methyldiphenylphosphonium 1-indenylide, 1-C9H6PMePh2 (1).
containing the ligand methyldiphenylphosphonium cyclopentadi-
enylide, C5H4PMePh2 [1]. This ligand belongs to a class of phospho-
nium cyclopentadienylides that were first reported in 1956 by
Ramirez and Levy [2a] who synthesized triphenylphosphonium
cyclopentadienylidene, C5H4PPh3 [2b–f]. They found inter alia that
this ylide is unusually inert; unlike normal ylides, it does not react
with ketones. They attributed this unusual stability to the electron
delocalization implied by resonance structure b, consistent with
the relatively high dipole moment of 7.0 D [2c].
+
PMePh2
P MePh2
+
PPh3
P Ph3
a
b
1
b
a
The first indenyl-derived phosphorus ylide, triphenylphospho-
nium 1-indenylide (1-C9H6PPh3), was reported by Crofts and Wil-
liamson in 1967 [4] while Rufanov et al. reported the synthesis
of two other phosphonium 1-indenylides, 1-C9H6P(CH2Ph)Ph2
and 1-C9H6P(CH2C6F5)Ph2, in 2004 [5]. However the chemistry of
these three potentially very interesting aromatic ligands has been
little investigated and, indeed, to our knowledge no other inde-
nyl-derived ylides have been reported. Furthermore, although
Further evidence for extensive delocalization of the
p electron
density was found in the crystal structure, which showed signifi-
cant shortening of the P–C5H4 bond [2g], and in the 13C NMR spec-
trum, which showed an unusually high field chemical shift for the
* Corresponding author. Fax: +1 613 533 6669.
E-mail address: bairdmc@chem.queensu.ca (M.C. Baird).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.05.027

J.H. Brownie, M.C. Baird / Journal of Organometallic Chemistry 693 (2008) 2812–2817
2813
aromatic ligands of the type 1-C9H6PR3 are prochiral with the re-
sult that their coordination compounds would exhibit planar chi-
rality, no transition metal complexes of any indenyl-derived ylide
appear to have been reported. We therefore describe herein the
synthesis and characterization of the new ligand, methyldiphenyl-
phosphonium 1-indenylidene, 1-C9H6PMePh2 (1) and of its chiral
ordered CH2Cl2 molecules. Each CH2Cl2 has 42 electrons, and occu-
pies about 60 Å3 in space theoretically. The larger volume of the
void in the crystal may be a result of the disorder. The contribu-
tions have been included in all derived crystal quantities although
the precise composition of the lattice solvate is somewhat
speculative.
chromium complex, Cr(g
5-1-C9H6PMePh2)(CO)3 (2).
2.1. Synthesis of [1-C9H7PMePh2]I
2. Experimental
A solution of 5.1 g 1-C9H7PPh2 (as a mixture of isomers) [6a]
(1.7 Â 10À2 mol) in 20 mL of THF was treated with 1.0 mL MeI
(1.6 Â 10À2 mol), and the reaction mixture was stirred for 2 days
while a white precipitate slowly formed. The resulting solid was
filtered, washed with ether (3 Â 10 mL) and dried under reduced
pressure to give 5.6 g of white [1-C9H7PMePh2]I (75% yield). 1H
NMR (CDCl3, 300 MHz): d 8.10–6.90 (m, Ph, possibly olefinic),
All syntheses were carried out under a dry, deoxygenated argon
atmosphere using standard Schlenk line techniques. Argon was
deoxygenated by passage through a heated column of BASF copper
catalyst, and then dried by passing through a column of 4A molec-
ular sieves. Handling and storage of air-sensitive organometallic
compounds was done using Schlenk techniques and an MBraun
Labmaster glove box. NMR spectra were recorded using Bruker
AV 300, AV 500 and AV 600 spectrometers, all 1H and 13C{1H}
NMR spectra being referenced to carbons or residual protons pres-
ent in the deuterated solvents with respect to TMS at d 0. 31P NMR
spectra were referenced to external 85% H3PO4. IR spectra were ac-
quired on a Perkin Elmer Spectrum One FT-IR spectrometer at a
spectral resolution of 4 cmÀ1. Elemental analyses were conducted
by Canadian Microanalytical Service Ltd. of Delta, BC.
Anhydrous dichloromethane, tetrahydrofuran, ethyl ether, hex-
anes and toluene were purchased from Aldrich in 18 L reservoirs
packaged under nitrogen, and were dried by passage through col-
umns of activated alumina (Innovative Technology Solvent Purifi-
cation System). The THF, Et2O and CH2Cl2 acquired in this way
were also subsequently stored over 4A molecular sieves to result
in residual water concentrations that were lower than 20 ppm
(Karl Fischer titrations). NMR solvents used for organometallic
compounds were degassed under vacuum and dried by passage
through a small column of activated alumina and storage over 4A
molecular sieves. All deuterated solvents were purchased from
Cambridge Isotope Laboratories, Inc. or CDN Isotopes. Most
chemicals were obtained from Aldrich or Strem and were used as
received or purified by established procedures. 1-Diphenylphosph-
inoindene, as a mixture of 1-diphenylphosphinoind-2-ene and
1-diphenylphosphinoind-1-ene, was synthesized according to a lit-
erature procedure [6a].
2
6.7–6.15 (m, olefinic), 3.18 (d, JP–H = 13.3 Hz, PMe), 2.85
(d, 2JP–H = 13.3 Hz, PMe). 31P NMR (CDCl3, 121 MHz): d 26.04, 13.52.
2.2. Synthesis of 1-C9H6PMePh2 (1)
A mixture of 1.30 g [1-C9H7PMePh2]I (2.94 Â 10À3 mol) and
0.126 g NaH (5.25 Â 10À3 mol) in 20 mL of THF was stirred for 4
days and then filtered. The solid residue was washed 3 Â 5 mL of
THF, and the combined solutions were concentrated to ꢀ20 mL
and then layered with 50 mL of hexanes and cooled to À30 °C to
give a light green solid. This was filtered, washed with 3 Â 20 mL
of hexanes, redissolved in 20 mL of CHCl3 and then taken to dry-
ness under reduced pressure again to yield 0.80 g (87%) of a green
solid that was used without further purification. X-ray quality
crystals and analytically pure 1 were obtained by crystallization
from a CH2Cl2 solution layered with hexanes and kept at À30 °C.
1H and 13C NMR data are listed in Table 1. 31P NMR (CDCl3,
121 MHz): d 5.69. Anal. Calc. for C22H19P: C, 84.06; H, 6.09. Found:
C, 84.38; H, 6.35%.
2.3. Synthesis of Cr(g
5-1-C9H6PMePh2)(CO)3 (2)
A solution of 0.435 g 1 (1.38 Â 10À3 mol) and 0.692 g Cr(CO)6
(3.46 Â 10À3 mol) in 25 mL diglyme was refluxed for 3 h before
being cooled and filtered through Celite. The Celite was washed
with 3 Â 10 mL of diglyme, and the resulting orange-red solution
was combined with 175 mL of hexanes to give a red-brown solid
which was collected and redissolved in ꢀ15 mL of CH2Cl2. Addition
of 40 mL of hexanes and cooling of this solution to À30 °C resulted
in the precipitation of 0.25 g of orange-brown product (40% yield).
Analytically pure, X-ray quality crystals of 2 were obtained by
recrystallization from a CH2Cl2 solution layered with hexanes at
X-ray crystal structure determinations were performed by Dr.
Ruiyao Wang in the X-ray Crystallography Laboratory at Queen’s
University. Crystals were mounted on glass fibers with epoxy glue,
and data collections were performed on a Bruker smart CCD 1000
X-ray diffractometer with graphite-monochromated MoK radia-
a
tion (k = 0.71073 Å) controlled with Cryostream Controller 700.
No significant decay was observed during data collections. Data
were processed on a Pentium PC using the Bruker AXS Crystal Struc-
ture Analysis Package, Version 5.10 [7a]. Neutral atom scattering
factors were taken from Cromer and Waber [7b]. The raw intensity
data were converted (including corrections for scan speed, back-
ground and Lorentz and polarization effects) to structure ampli-
tudes and their esds using the program SAINT, which corrects for
Lp and decay. Absorption corrections were applied using the pro-
gram SADABS. All non-hydrogen atoms were refined anistropically.
The positions for all hydrogen atoms were calculated (unless
otherwise stated) and their contributions were included in the
structure factors and calculations.
For 2, difference electron density maps revealed the presence of
disordered lattice solvate molecules, which were ultimately ac-
counted for through the use of the SQUEEZE subroutine of the PLATON
software suite [7c]. Two solvent accessible voids per lattice were
found, comprising an equal volume of 203.1 Å3 and contributing
a total of 38.8 electrons. The voids were thus assigned to two dis-
À30 °C. IR (CH2Cl2):
m .
(CO) 1916 (s), 1816 (s), 1802 (sh) cmÀ1 1H
and 13C NMR data are listed in Table 2. 31P NMR (CD2Cl2,
121 MHz): d 19.84. Anal. Calc. for C25H19Cr1O3P1 Á 0.5CH2Cl2: C,
62.14; H, 4.09. Found: C, 61.90; H, 4.04%.
3. Results and discussion
3.1. Syntheses of 1-C9H6PMePh2 (1) and Cr(
(2)
g
5-1-C9H6PMePh2)(CO)3
Compound 1 was synthesized using a protocol very similar to
that used previously by Mathey et al. [8] and ourselves [1] to ob-
tain C5H4PMePh2. The precursor, 1-diphenylphosphinoindene,
was alkylated with MeI to give the corresponding phosphonium
salt [1-C9H7PMePh2]I (75% yield) as a mixture of the two isomers
shown in Scheme 1 [6a]. The 1H NMR spectrum of the phospho-
nium salt is very complicated in the olefinic region and exhibits

2814
J.H. Brownie, M.C. Baird / Journal of Organometallic Chemistry 693 (2008) 2812–2817
Table 1
1H and 13C NMR data for 1
Position
d (1H)a
Multiplicity
J (Hz)
d (13C)
Multiplicity
J (Hz)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
66.14
126.30
105.00
120.82
117.28
117.91
117.36
137.79
135.42
12.97
d
d
d
s
s
s
1JP–C = 120.8
2JP–C = 17.6
3JP–C = 15.4
6.74
6.64
7.68
6.97
6.84
7.04
t
t
m
t
t
JH–H = JP–H = 4.5
JH–H = JP–H = 4.2
3JH–H = 7.2
3JH–H = 6.8
3JH–H = 7.9
d
s
d
d
d
d
d
d
d
3JP–C = 15.4
2JP–C = 14.3
1JP–C=62.6
1JP–C = 87.8
2JP–C = 12.1
3JP–C = 11.0
4JP–C = 3.3
2.5
d
2JP–H = 12.6
127.13
129.45
132.68
132.93
7.55–7.52
7.67–7.63
7.67–7.53
m
m
m
a
The proton correspond to the proton attached to the carbon atom with the same position number in Fig. 2.
Table 2
the product is easily separated and purified. Analytically pure
material and X-ray quality crystals of 1 were obtained by recrystal-
lization from a CH2Cl2 solution layered with hexanes and kept at
À30 °C.
1H and 13C NMR data for 2
Position d (1H)a
Multiplicity J (Hz)
d (13C) Multiplicity J (Hz)
1
57.2
d
1JP–C
113.8
Using the indenyl system offers several advantages relative to
the analogous Cp-derived phosphonium ylide, C5H4PMePh2. Thus,
for instance, the precursor phosphine, 1-C9H7PPh2, is thermally
more stable than is CpPPh2 which decomposes if not used immedi-
ately after synthesis [8,9]. In addition, during the deprotonation of
the two phosphonium salts, the resulting methyldiphenylphospho-
nium 1-indenylide, 1, is formed in higher yields than is
C5H4PMePh2 [1,8]. Finally, 1 also exhibits higher solubilities in aro-
matic solvents than does C5H4PMePh2 [1,8].
2
3
4
5
4.76
5.47
7.66
7.00
m
m
m
td
3JH–H 3.0
3JH–H 3.0
95.68
80.31
127.53
d
d
s
2JP–C 13.9
3JP–C 12.5
3JH–H 7.6 123.28
4JH–H 1.5
s
6
7
8,9
6.92
6.90
t*
3JH–H 8.7 122.16
3JH–H 7.6 124.60
109.80
s
s
d
d
d
d*
JP–C 16.6
JP–C 16.6
1JP–C 65.2
109.72
14.68
10
11
12
13
14
CO
2.88
d
2JP–H
13.2
To synthesize 2, 1 was refluxed in diglyme with an excess
(2–3 equiv.) of Cr(CO)6 (Scheme 2), and gave 2 in 40% yield. Purifi-
cation to yield analytically pure material and X-ray quality crystals
was accomplished by recrystallization from a CH2Cl2 solution lay-
ered with hexanes and kept at À30°C.
123.10
122.43
130.46
130.25
133.67
133.46
134.97
134.93
241.16
d
d
d
d
d
d
d
d
s
1JP–C 87.4
1JP–C 90.2
2JP–C 12.5
2JP–C 12.5
3JP–C 9.7
3JP–C 9.7
4JP–C 2.8
4JP–C 2.8
7.78–7.61
7.78–7.61
7.78–7.61
m
m
m
3.2. IR and NMR Spectra of 1 and 2
The IR spectrum of 2 in CH2Cl2 exhibits t(CO) at 1916 (s), 1816
a
(s) and 1802 (sh) cmÀ1 (Fig. 1). Both the frequencies and the
relative intensities of the carbonyl bands are similar to those of
See Fig. 2 for atom numbering scheme.
The peaks for protons 6 and 7 overlap and the multiplicity is described as
*
inferred from the observed patterns and that expected for these peaks.
the related phosphonium cyclopentadienylide complexes Cr(g5
-
C5H4PMePh2)(CO)3 [1] and Cr(g
5-C5H4PPh3)(CO)3 [10], although
the doubly degenerate E mode is clearly broadened because of
the asymmetry in the structure and loss of threefold symmetry
in the compound.
two P–Me doublets at d 3.18 and 2.85, the ratio of intensities of the
two isomers varying from experiment to experiment. Similarly the
31P NMR spectrum exhibits two resonances at d 26.04 and 13.52
with a similar ratio of intensities. The phosphonium salt was suffi-
ciently pure (NMR) that it could be used as obtained for the synthe-
sis of 1.
The phosphonium 1-indenylide 1 was obtained in excellent
yield (87%) by deprotonation of the corresponding phosphonium
iodide with an excess of NaH in THF. Although this reaction is slow,
Fig. 2 shows the scheme used to label the various 1H and 13C
sites in 1 and 2. 1H NMR spectra of 1 and 2 are shown in Figs. 3
and 4, respectively, and 1H and 13C NMR assignments for 1 and 2
are given in Tables 1 and 2, respectively. Although there is in some
cases overlapping of resonances, NOESY, COSY, HSQC and HMBC
spectra were acquired for both compounds and made possible 1H
and 13C assignments which are unambiguous.
P+MePh2 + I-
PPh2
PPh2
MeI
NaH
+ Cr(CO)6
Ph2MeP
PMePh2
C
O
+
Cr
Cr
P MePh2
P+MePh2
C
O
C
O
O
C
C
C
O
O
P+MePh2 + I-
Scheme 1. The synthesis of 1.
Scheme 2. The synthesis of the chromium complex 2, demonstrating the nature of
the planar chirality which is created on coordination.

J.H. Brownie, M.C. Baird / Journal of Organometallic Chemistry 693 (2008) 2812–2817
2815
50
CHDCl2
24
0
7.00 6.95 6.90 6.85
2000 1900
1800
1700
1600
1500
cm-1
Fig. 1. The IR spectrum of Cr(
g
5-1-C9H6PMePh2)(CO)3 (2) in CH2Cl2.
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
Fig. 4. The 1H NMR spectrum of Cr(
g
5-1-C9H6PMePh2)(CO)3 (2) in CD2Cl2.
14
13
12
13
12
11
P
Ph
CH3
10
7
1
6
5
8
9
2
3
4
Fig. 2. The labeling scheme used for the NMR assignments of 1 and 2.
Fig. 5. The molecular structure of 1-C9H6PMePh2.
7.10 7.00 6.90 6.80 6.70 6.60
CHCl3
δ
8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5
Fig. 3. The 1H NMR spectrum of 1-C9H6PMePh2 (1) in CDCl3.
The indenyl 1H and 13C chemical shifts and coupling constants
of 1 are very similar to those of the related phosphonium 1-indeny-
lides 1-C9H6P(CH2Ph)Ph2 and 1-C9H6P(CH2C6F5)Ph2 [5]. The 13C
chemical shift of the C(1) resonance of 1 (d 66.1) is at a slightly
lower field than those of 1-C9H6P(CH2Ph)Ph2 (d 59.9) and 1-
C9H6P(CH2C6F5)Ph2 (d 62.2) [5], but 13 ppm to higher field than
the ylidic carbon resonance of C5H4PMePh2 (d 79.2) [1]. Interest-
ingly, the chemical shift of the C(1) resonance of 1 is ꢀ17.5 ppm
to higher field than that of the corresponding resonance of 1-diph-
enylphosphinoind-2-ene (d 48.6) [6a] while 1JP–C in 1 (120.8 Hz) is
significantly higher than that of 1-diphenylphosphinoind-2-ene
Fig. 6. The molecular structure of Cr(g
5-1-C9H6PMePh2)(CO)3.
1
(33.5 Hz) [6a]. This increase in JP–C is to be anticipated [6b]. The
Coordination of 1 to the Cr(CO)3 moiety results in significant
changes in the 1H, 13C and 31P NMR parameters of the ligand. In
the 1H NMR spectrum of 2, the C5H4 protons H(2) and H(3) shift
31P NMR chemical shift of 1 (d 5.69) is at a slight higher field than
that of the related C5H4PMePh2 (d 7.95) [1].

2816
J.H. Brownie, M.C. Baird / Journal of Organometallic Chemistry 693 (2008) 2812–2817
Table 3
upfield from d 6.74 and 6.64 in the uncomplexed ligand to d 4.76
Structural data for compounds 1 and 2
and 5.47. A similar upfield shift for the ring protons was observed
upon complexation of the related ylide, C5H4PMePh2, but the
changes were somewhat smaller (ꢀ1.5 ppm vs. ꢀ2 ppm) [1]. The
P–Me resonance of 1 (H10) shift downfield from d 2.48 to d 2.88,
but there is little change in the phenyl region of the spectrum.
The 13C NMR of 2 reveals some interesting changes. The reso-
nance of the ylidic carbon, C(1), shifts from d 66.14 in 1 to d 57.2
in 2, a change similar to that observed for the ylidic carbon of
C5H4PMePh2 on complexation albeit smaller in magnitude [1].
The resonances of the C5 ring carbons C(2) and C(3) also shift, from
d 126.30 and 105.00 to d 95.68 and 80.31, respectively. The reso-
nances of the two other C5 ring carbons C(8) and C(9) also shift dra-
matically on complexation, from d 137.79 and 135.42 to d 109.80
and 109.72. This shift in the resonances of carbons C(8) and C(9)
resembles the shift seen in the other C5 carbon resonances (car-
bons C(2) and C(3)). The two resonances of carbons C(8) and C(8)
overlap so closely that they could not be distinguished conclusively
in spite of the various 2D NMR techniques employed.
1
2
Empirical formula, fw
C
22H19P, 314.34
C25.50H20ClCrO3P,
492.84
180(2)
0.71073 Å
Orthorhombic
Pna2(1)
15.7408(18)
18.114(2)
8.5337(10)
90
90
90
2433.2(5)
4
1.345
Temperature (K)
Wavelength
Crystal system
Space group
a (Å)
180(2)
0.71073 Å
Monoclinic
P2(1)/c
9.9353(18)
17.900(3)
10.0935(18)
90
112.681(4)
90
2323.09(18)
4
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
q
(calculated) (Mg/m3)
1.261
0.163
664
Absorption coefficient (mmÀ1
F(000)
)
0.669
1012
Crystal size (mm3)
0.40 Â 0.06 Â 0.04
0.35 Â 0.15 Â 0.04
2.25–21.75°
À16 6 h 6 16,
À18 6 k 6 18,
À8 6 l 6 8
15526
Theta range for data collection 2.22–25.00°
Another feature of interest in the 13C NMR spectrum of 2 is the
inequivalence of the diastereotopic P–Ph groups. This leads to two
distinct sets of peaks for these carbons with identical coupling con-
stants (see Table 2). The CO resonance of 2 appears at d 241.14,
while the 31P NMR resonance of 2 is observed at lower field (d
19.84) than that of 1 (d 5.69). Similar shifts occur on coordination
Index ranges
À11 6 h 6 11,
À21 6 k 6 20,
À11 6 l 6 11
9436
2906 [R(int) = 0.0697]
100.0%
Reflections collected
Independent reflections
Completeness to
2863 [R(int) = 0.0601]
99.7%
theta = 25.00°
Absorption correction
Maximum and minimum
transmission
Empirical
0.4463 and 0.3000
Multi-scan
0.9737 and 0.7995
of C5H4PMePh2 to chromium in Cr(g
5-C5H4PMePh2)(CO)3.
3.3. Molecular structures of 1 and 2
Refinement method
Full-matrix least-
squares on F2
2906/0/208
1.00
Full-matrix least-
squares on F2
2863/1/271
1.000
R1 = 0.0421,
wR2 = 0.0981
R1 = 0.0528,
wR2 = 0.1037
Data/restraints/parameters
The molecular structures of 1 and 2 are shown in Figs. 5 and 6,
respectively. The structural data for 1 and 2 are listed in Table 3,
selected bond lengths and angles in Table 4. Also included in Table
4 for purposes of comparison are the bond lengths and angles for
methyldiphenylphosphonium cyclopentadienylide, and of its chro-
mium(0) complex [1].
Goodness-of-fit on F2
Final R indices [I > 2sigma(I)] R1 = 0.0455,
wR2 = 0.0873
R indices (all data)
R1 = 0.0723,
wR2 = 0.0919
Largest difference in peak
and hole
0.393 and À0.332 e ÅÀ3 0.295 and À0.227 e ÅÀ3
As can be seen, the bond lengths and angles are largely as would
be anticipated. The P(1)–C(1) bond length is of interest because, as
Table 4
Selected bond lengths and angles for 1 and 2
Bond (Å)
1
C5H4PMePh2
(Molecule 1)
2
Cr(g
5-C5H4PMePh2)(CO)3
(Molecule 2)
P(1)–C(1)
P–Me
1.711(2)
1.787(2)
1.788
1.7277(17)
1.799(2)
1.81
1.7268(17)
1.7921(19)
1.802
1.753(5)
1.781(5)
1.788
1.759(3)
1.789(3)
1.796
P–Ph avg.
M–C5 Centroid
C(1)–C(2)
C(1)–C(5)
C(2)–C(3)
C(4)–C(5)
C(3)–C(4)
C(1)–metal
C(2)–metal
C(3)–metal
C(4)–metal
C(5)–metal
1.854
1.848
1.420(3)
1.432(3)
1.364(3)
1.423(3)
1.421(3)
1.429(3)
1.414(3)
1.374(3)
1.384(3)
1.405(3)
1.413(2)
1.429(2)
1.384(2)
1.383(3)
1.407(3)
1.443(7)
1.461(7)
1.387(7)
1.405(7)
1.427(7)
2.170(5)
2.163(5)
2.201(5)
2.259(5)
2.278(5)
1.427(4)
1.429(4)
1.392(4)
1.397(4)
1.422(4)
2.185(2)
2.204(2)
2.226(3)
2.217(3)
2.191(3)
Bond angles (°)
C(1)–P–Me
C(1)–P–Ph avg.
Me–P–Ph avg.
Ph–P–Ph
P–C(1)–C5 Centroid
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
C(4)–C(5)–C(1)
C(5)–C(1)–C(2)
111.90(10)
111.16
107.05
108.33(10)
174.9
110.1(2)
108.2(2)
107.96(19)
107.09(18)
106.64(19)
111.46(9)
111.44
106.96
108.37(8)
172.4
107.42(19)
108.85(18)
108.74(18)
107.47(18)
107.51(16)
111.96(9)
110.64
108.44
106.55(7)
178.1
108.36(16)
108.16(18)
108.87(15)
107.50(17)
107.11(16)
112.6(2)
109.6
108.6
107.8(2)
174.7
109.3(5)
107.9(5)
109.6(5)
106.8(4)
106.4(4)
111.08(13)
109.78
109.38
107.37(12)
178.9
108.3(3)
108.3(3)
108.3(3)
108.0(3)
107.1(2)
Data for C5H4PMePh2 and Cr(g
5-C5H4PMePh2)(CO)3 are from Ref. [1].

J.H. Brownie, M.C. Baird / Journal of Organometallic Chemistry 693 (2008) 2812–2817
2817
in the case of phosphonium cyclopentadienylides in general, it pro-
Acknowledgements
vides a useful estimation of the P–C double bond character and
hence the relative contributions of the resonance structures 1a
and 1b to the bonding [1,2g]. Thus the P(1)–C(1) bond of 1, at
1.711(2) Å, is significantly shorter than the P–Ph bonds in this mol-
ecule (average 1.788 Å, typical of P–C single bond in phenyl phos-
phonium ylides), and is shorter also than the P–C bonds of both the
analogous Cp derived ylide, C5H4PMePh2 (1.727 Å average) [1] and
the Ramirez ylide C5H4PPh3(1.718 (2) Å) [2g]. It is also shorter than
the P(1)–C(1) bond length of the phosphonium 1-indenylide, 1-
C9H6P(CH2Ph)Ph2, which is 1.733(4) Å [5]. The shortening of the
P(1)–C(1) indicates that the P(1)–C(1) bond in 1 exhibits greater
double bond character than in the other ylides. All, of course, are
much longer than the P@CH2 bond in Ph3P@CH2 (1.66 Å) [11], a
typical example of a non-resonance stabilized ylide with consider-
able double bond character.
We thank the Government of Ontario (Ontario Graduate Schol-
arship to J.H.B.), Queen’s University (Queen’s Graduate Award to
J.H.B.) and the Natural Sciences and Engineering Research Council
(Discovery Grant to M.C.B.).
Appendix A. Supplementary material
CCDC 688424 and 688425 contain the supplementary crystallo-
graphic data for 1-C9H6PMePh2 and Cr(g
5-1-C9H6PMePh2)(CO)3.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif. Crystallographic details, including figures of
1-C9H6PMePh2 (1) and Cr(g
5-1-C9H6PMePh2)(CO)3 (2), showing
complete numbering schemes and thermal ellipsoid figures, and
tables of positional and thermal parameters and bond lengths
and angles. Supplementary data associated with this article can
TheC5 ringbondsof1 areonaveragelongerthantheC5 ringbonds
of the Ramirez ylide and C5H4PMePh2 [1,2g]. The C–C–C bond angles
of the C5 ring in 1 are all close to the values expected for a regular
pentagon (108°), and the similarity in the C–C lengths tend to pro-
be
found,
in
the
online
version,
at
doi:10.1016/
j.jorganchem.2008.05.027.
vide evidence of delocalization of the
p bond electron density.
On coordination to the –Cr(CO)3 fragment, the ylidic ligand
undergoes several modifications. Elongation of the P(1)–C(1) bond
is observed, which is typical of this class of ligand upon coordina-
tion [1]. The P(1)–C(1) bond length of 1.753(5) Å in 2 is similar in
References
[1] (a) J.H. Brownie, M.C. Baird, H.L. Schmider, Organometallics 26 (2007) 1433;
(b) J.H. Brownie, M.C. Baird, D.R. Laws, W.E. Geiger, Organometallics 26 (2007)
5890.
length to those observed in the complexes Cr(
g
5-C5H4PMePh2)-
[2] (a) F. Ramirez, S. Levy, J. Org. Chem. 21 (1956) 488;
(b) F. Ramirez, S. Levy, J. Org. Chem. 21 (1956) 1333;
(c) F. Ramirez, S. Levy, J. Am. Chem. Soc. 79 (1957) 67;
(d) F. Ramirez, S. Dershowitz, J. Org. Chem. 22 (1957) 41;
(e) F. Ramirez, S. Levy, J. Am. Chem. Soc. 79 (1957) 6167;
(f) F. Ramirez, S. Levy, J. Org. Chem. 23 (1958) 2035;
(g) H.L. Ammon, G.L. Wheeler, P.H. Watts Jr., J. Am. Chem. Soc. 95 (1973) 6158;
(h) G.A. Gray, J. Am. Chem. Soc. 95 (1973) 7736;
(CO)3 (1.759(3) Å) and Cr(
g
5-C5H4PPh3)(CO)3 (1.751(5) Å and
1.755(6) Å). The increase in bond length is indicative of a greater
contribution of the zwitterionic resonance structure of the ligand
upon coordination indicating a greater degree of aromatic charac-
ter. The P(1)–C(1)–C5(centroid) bond angle (174.7°) remains simi-
lar to that observed in the free ligand, but falls between those
(i) For a recent computational study, see: P. Laavanya, B.S. Krishnamoorthy,
K. Panchanatheswaran, M.J. Manoharan, Mol. Struct., THEOCHEM 716 (2005)
149.
observed for Cr(g -
5-C5H4PMePh2)(CO)3 (178.9°) and Cr(g5
C5H4PPh3)(CO)3 (173.4° and 169.0°) [1,2g]. The bond lengths of
the C5 ring of 2 are, on average, longer than in the free ligand, as
[3] Black, insoluble substances are generally obtained, presumably containing
polymeric materials.
[4] P.C. Crofts, M.P. Williamson, J. Chem. Soc. (C) (1967) 1093.
[5] K.A. Rufanov, B. Ziemer, M. Hummert, S. Schutte, Eur. J. Inorg. Chem. (2004)
4759.
[6] (a) K. Fallis, G. Anderson, N. Rath, Organometallics 11 (1992) 885;
(b) T.A. Albright, Org. Magn. Res. 8 (1976) 489. and references therein.
[7] (a) Bruker AXS Crystal Structure Analysis Package: Bruker (2000). SHELXTL
Version 6.14. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker (2005). XPREP
Version 2005/2. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker (2005). SAINT
observed for Cr(g
5-C5H4PMePh2)(CO)3 [1].
An interesting consequence of using the prochiral phosphonium
1-indenylide is that, on coordination, a pair of enantiomers, exhib-
iting planar chirality, are formed (Scheme 2). This property is antic-
ipated to be of importance if catalytically active complexes of 1 are
formed in future.
.
.
.
Version 7.23A. Bruker AXS Inc., Madison,Wisconsin, USA. Bruker (2006). APEX2.
Version 2.0–2. Bruker AXS Inc., Madison, Wisconsin, USA.;
(b) D.T. Cromer, J.T. Waber, International Tables for X-ray Crystallography, vol.
4, Kynoch Press, Birmingham, UK, 1974. Table 2.2 A;
4. Summary
The new aromatic ligand methyldiphenylphosphonium 1-
indenylide (1-C9H6PMePh2, 1) and its chromium(0) complex,
(c) P.V.D. Sluis, A.L. Spek, Acta Crystallogr., Sect. A 46 (1990) 194.
[8] F. Mathey, J.-P. Lampin, Tetrahedron 31 (1975) 2685.
[9] C.P. Casey, R.M. Bullock, W.C. Fultz, A.L. Rheingold, Organometallics 1 (1982)
1591.
[10] J.C. Kotz, D.G. Pedrotty, J. Organomet. Chem. 22 (1970) 425.
[11] (a) J.C.J. Bart, J. Chem. Soc. (B) (1969) 350;
Cr(g
5-1-C9H6PMePh2)(CO)3 (2) have been synthesized and charac-
terized. The molecular structures of both compounds have been
obtained, and compound 2 is shown to exhibit planar chirality
resulting from coordination of the prochiral aromatic ligand.
(b) J. Plíva, J.W.C. Johns, L. Goodman, J. Mol. Spectrosc. 140 (1990) 214.