Diastereoselective synthesis of a "chiral-at-Ru" secondary phosphine complex

Article abstract of DOI:10.1016/j.ica.2010.12.058

Synthesis of the half-sandwich ruthenium complex [RuCl(η⁵- indenyl){P(Bu^t)(Ph)H}(PPh₃)], 2, containing an unsymmetrically-substituted secondary phosphine, is described. A 60:40 kinetic distribution of the resulting diastereomers 2a and 2b shifts in solution at room temperature to give predominantly 2a. The relative stereochemistries at ruthenium and the secondary phosphine in each diastereomer have been assigned based on ¹H NOESY NMR and crystallographic data.

Full text of DOI:10.1016/j.ica.2010.12.058

Inorganica Chimica Acta 369 (2011) 133–139
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Diastereoselective synthesis of a ‘‘chiral-at-Ru’’ secondary phosphine complex
Gregory L. Gibson a, Krista M.E. Morrow a, Robert McDonald b, Lisa Rosenberg a,
⇑
a Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6
b X-ray Crystallography Laboratory, Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 30 December 2010
Synthesis of the half-sandwich ruthenium complex [RuCl(
g
5-indenyl){P(But)(Ph)H}(PPh3)], 2, containing
an unsymmetrically-substituted secondary phosphine, is described. A 60:40 kinetic distribution of the
resulting diastereomers 2a and 2b shifts in solution at room temperature to give predominantly 2a.
The relative stereochemistries at ruthenium and the secondary phosphine in each diastereomer have
been assigned based on 1H NOESY NMR and crystallographic data.
Dedicated to Professor Robert Bergman
Keywords:
Secondary phosphine complex
Ruthenium
Ó 2010 Elsevier B.V. All rights reserved.
Chiral-at-metal
Epimerization
Diastereoselectivity
NOESY NMR
1. Introduction
(Ph)H}(PPh3)], 2 (Scheme 2), and equilibration between the two dia-
stereomers in solution, which leads to a thermodynamic product
We have previously described the synthesis of half-sandwich
ruthenium complexes of symmetrically substituted secondary
mixture of enhanced diastereomeric excess.
phosphines of the formula [Ru(
Their subsequent dehydrohalogenation reactions generate highly
reactive terminal phosphido complexes containing Ru–PR2
-bond [2]. As shown in Scheme 1, these phosphido complexes
g
5-indenyl)Cl(PR2H)(PPh3)] [1].
2. Experimental
a
2.1. General details
p
react with alkyl halides, alkenes and alkynes to generate new
Unless otherwise noted, all reactions and manipulations were
performed under nitrogen in an MBraun Unilab 1200/780 glovebox
or using conventional Schlenk techniques. All solvents were
sparged with nitrogen for 25 min and dried using an MBraun Sol-
vent Purification System (SPS). Deuterated solvents were pur-
chased from Cambridge Isotope Labs (CIL), freeze–pump–thaw
degassed, and vacuum transferred from sodium/benzophenone
(d6-benzene, d8-toluene) or calcium hydride (d-chloroform) before
P–Cbonds, andwearecurrentlypursuingtheappropriateconditions
to make these reactions catalytic, using [Ru(g
5-indenyl)Cl(PPh3)2],
1, as a precatalyst.
This is a preliminary report of our efforts to extend this chem-
istry to the stereoselective P–C bond-forming reactions of unsym-
metrically-substituted secondary phosphines. The chirality at
ruthenium in the symmetric secondary phosphine complexes in
Scheme 1 is evident from their 13C and 1H NMR spectra, which
show distinct chemical shifts for peaks due to the diastereotopic
substituents at the coordinated secondary phosphine [1]. An
intriguing strategy for the production/resolution of chiral phos-
phines would capitalize on this chirality through the selective
enhancement of the rate of P–C bond formation for one of two
diastereomers resulting from the addition of a racemic mixture of a
use. [RuCl(g
5-indenyl)(PPh3)2] was prepared as described previ-
ously [1]. HPButPh was purchased from Sigma–Aldrich Canada
and used as received. NMR spectra were recorded on a Bruker
AVANCE 500 operating at 500.13 MHz for 1H, 125.77 MHz for 13C,
and 202.46 MHz for 31P, or on a Bruker AVANCE 300 operating at
300.13 MHz for 1H, and 121.49 MHz for 31P. Chemical shifts are re-
ported in ppm at ambient temperature unless otherwise noted. 1H
chemical shifts are referenced against residual protonated solvent
peaks at 7.16 ppm (C6D5H) and 7.24 ppm (CHCl3). 13C chemical
shifts are referenced against CDCl3 at 77.5 ppm. All 1H, 13C chemi-
cal shifts are reported relative to tetramethylsilane (TMS), and 31P
chemical shifts are reported relative to 85% H3PO4(aq.). Elemental
analysis was performed by Canadian Microanalytical Service Ltd.,
P-chiral secondary phosphine to [Ru(
agingly, in this context, we report here the stereoselective synthesis
g
5-indenyl)Cl(PPh3)2]. Encour-
of the mixed phosphine complex [Ru(g
5-indenyl)Cl{P(But)-
⇑
Corresponding author.
E-mail address: lisarose@uvic.ca (L. Rosenberg).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.12.058

134
G.L. Gibson et al. / Inorganica Chimica Acta 369 (2011) 133–139
stereogenic
Ph3P
diastereotopic
R
Ru
Cl
R
P
H
– KCl
– HOBut
KOBut
Ru
R
P
Ph3P
R
P-C bond-forming reactions
MeI
Bun
Ph
Bun
R
Ru
R
Ru
R
Ru
R
Ph3P
P
P
P
Ph3P
Ph3P
Ph
R
R
I
Me
Scheme 1.
Delta, BC, Canada. IR spectra were recorded on a Perkin–Elmer FTIR
Spectrum One spectrophotometer using KBr pellets under a nitro-
gen atmosphere.
t
HPBu Ph
Ru
Ru
2.2. Synthesis of [RuCl(5-indenyl){P(But)(Ph)H}(PPh3)] (2a and 2b)
Ph 3 P
Ph3 P
*
t
PPh3
Cl
PBu PhH
– PPh3
Cl
2a + 2b
(racemates)
[RuCl(5-indenyl)(PPh3)2] (1) (0.345 g, 0.44 mmol) and HPButPh
(0.155 g, 0.93 mmol) were added to a Schlenk flask with a stir
bar. Dichloromethane (ꢀ30 mL) was added and the resulting dark
red solution was refluxed for 3.75 h, at which point the solvent was
removed under vacuum to give a dark red oil. Washing with hex-
anes (4 ꢁ 20 mL) gave an orange powder, which was isolated by fil-
tration, and dried under vacuum. Crude yield: 0.151 g, 0.22 mmol,
50%. This powder was clean except for traces of residual PPh3,
HPButPh, and CH2Cl2, and contained diastereomers a and b in a
60:40 ratio. A portion of the product was recrystallized by slow dif-
fusion of hexanes into a concentrated dichloromethane solution.
The resulting red crystals were used for both X-ray diffraction (Sec-
tion 2.4) and elemental analysis.
1
Scheme 2.
were added to a Schlenk flask with a stir bar. The addition of tolu-
ene (ꢀ5 mL) gave an orange solution that began to darken to pur-
ple after about 5 min of stirring at room temperature. After 25 min
of stirring the mixture was a deep blue color, with a yellow menis-
cus. At this point the solvent was removed under vacuum, leaving a
dark green–yellow oil, which was dissolved in d6-benzene and ana-
lyzed by 31P{1H} NMR within 20 min. The spectrum showed some
unreacted 2a and 2b (38%, 21:1 a:b), as well as signals assigned to
two isomers of the corresponding terminal phosphido complexes 3
and 30 (1:7.3), other signals assigned to the two phosphido decom-
position products 4, 40 (16%, 1:1.3), and several unassigned signals
(9%).
IR (KBr, cmꢂ1): 2371 (w,
mP–H), 2338 (m, mP–H); Anal. Calc. for
C
37H37ClP2Ruꢃ0.33CH2Cl2.1 C, 63.31; H, 5.36. Found: C, 63.75; H,
5.52%. Mp. 186 °C (decomposed).
2.3. 1H and 13C{1H} NMR data for 2a and 2b
Tables 1 and 2.
2.5. Crystallographic data
2.5.1. X-ray structure determination
2.4. Reaction of [RuCl(5-indenyl){P(But)(Ph)H}(PPh3)] (2a and 2b)
Crystals of 2 were grown via slow diffusion of hexanes into a
dichloromethane solution of the compound. Crystallographic
experimental data and refinement details can be found in Table 3.
All non-hydrogen atoms of the ruthenium complex molecule were
refined with isotropic displacement parameters. Hydrogen atoms
attached to carbons were assigned positions based on the idealized
sp2 or sp3 geometries of their attached atoms, and were given
thermal parameters 20% greater than those of the parent carbons.
The hydrogen atom attached to phosphorus was located from a
with KOBut
A powder sample of [RuCl(g
5-indenyl){P(But)(Ph)H}(PPh3)] (2a
and 2b) (0.036 g, 0.053 mmol) and KOBut (0.008 g, 0.07 mmol)
1
We have previously observed the tendency of these mixed phosphine complexes
to retain solvent, even after prolonged drying under vacuum (see Ref. [1]); the 1H
NMR spectrum of the sample submitted for analysis does indicate the presence of
residual dichloromethane.

G.L. Gibson et al. / Inorganica Chimica Acta 369 (2011) 133–139
135
difference Fourier map, and its atomic coordinates and isotropic
displacement parameter were allowed to freely refine. Attempts
to refine peaks of residual electron density as disordered or par-
tial-occupancy solvent dichloromethane chlorine or carbon atoms
were unsuccessful. The data were corrected for disordered electron
density through use of the SQUEEZE procedure [4a] as implemented
in PLATON [4b,c].
A total solvent-accessible void volume of
1079.1 Å3 with a total electron count of 182 (consistent with four
molecules of solvent dichloromethane, or one-half molecule per
formula unit of the ruthenium complex molecule) was found in
the unit cell.
3. Results and discussion
3.1. Synthesis of diastereomeric mixtures of 2
The unsymmetrically-substituted secondary phosphine HPButPh
reacts with complex 1 in refluxing dichloromethane to give com-
plete conversion to the mixed phosphine complex 2 in 3–4 h.
After removal of the solvent under vacuum, 31P{1H} NMR spec-
troscopy of the resulting red oil consistently shows the presence
of two diastereomers, 2a and 2b, in an approximate ratio of
60:40.2,3 Washing with hexanes gives 2 as an orange powder, still
with a 60:40 mixture of a and b, as determined by 31P{1H} NMR
recorded immediately after the sample is dissolved in NMR solvent
(either d1-chloroform or d6-benzene). However, as shown in Fig. 1,
over time in solution the diastereomer ratio shifts to give predom-
inantly 2a, indicating that (i) the diastereomers are in equilibrium
and (ii) diastereomer 2a is the more thermodynamically stable
product.
Removal of the residual PPh3 and HPButPh from this orange
powder requires either copious washing with hexanes or recrystal-
lization from dichloromethane and hexanes. The latter technique
gives dark red crystalline material that tends to be rich in 2b rela-
tive to the ‘‘kinetic’’ 60:40 product distribution described above,
with the highest relative amounts of 2b being observed when the
recrystallization takes place at low temperature in the freezer.
Thus, while solution studies indicate the higher thermodynamic
stability of 2a, complex 2b is the less soluble isomer. These differ-
ences present some interesting possibilities for obtaining one or
both of the isomers in a pure form, which would allow us to study
the kinetics of the approach to diastereomer equilibrium as a func-
tion of temperature. We continue to pursue this strategy for estab-
lishing the mechanism of epimerization, in particular to better
understand the importance of associative versus dissociative sub-
stitution processes for this
g
5-indenyl system.4
3.2. NMR characterization of the diastereomers of 2
The 1H NMR spectra of 2a and 2b are sufficiently distinct to al-
low unequivocal assignment of peaks due to the P–H, indenyl, and
But protons for each diastereomer in the mixtures we isolated
(Table 1, Section 2.3), and the general attribution of aromatic peaks
to either the PPh3 or the secondary phosphine Ph for each diaste-
reomer. Diagnostic P–H signals, centered between 5 and 6 ppm, ex-
hibit the expected large, 1JPH coupling (362 Hz (a), 346 Hz (b)). The
chirality at Ru renders diastereotopic the protons on either side of
2
In
a
representative experiment, 31P{1H} NMR of an aliquot removed before
reaction had gone to completion showed the same 60:40 ratio of 2a and 2b.
3
2
202.5 MHz 31P{1H} data (d) for 2 in d1-chloroform: (a) 85.5 (d, JPP = 43 Hz,
HPButPh), 42.7 (d, PPh3); (b) 70.2 (d, JPP = 43 Hz, HPButPh); 51.4 (d, PPh3).
2
4
Previous studies of phosphine substitution reactions at 1 point to predominantly
dissociative pathways for this crowded, bis(PPh3) complex, (see Ref. [3]) but
nevertheless the importance of variable hapticity of the indenyl ligand in our
systems remains an open question.

136
G.L. Gibson et al. / Inorganica Chimica Acta 369 (2011) 133–139
Table 2
125 MHz 13C{1H} NMR data at 300 K: d in ppm (multiplicity, JPC or x1/2 in Hz).a
g
5-Indenyl
PPh3 both isomers
HPBut-Ph
Ph
C7, C4
C6, C5
C3a,C7a
D
(C3a,7a
d
C2
C3, C1
But
b
)
2a 125.1 (s)
127.8 (s) 111.4 (br s,
126.8 (s) 10)
108.9 (d, 6)
ꢂ20.6
81.2
(s)
65.4 (d,
13)
61.5 (s)
134.7–133.9 (br)
133.9–132.1 (br)
129.5–128.7 (br om)
128.1–126.8 (overlapping, some br) br in
baseline
135.9 (d, 40)
133.2 (d, 8)
129.4 (dd, 18,
1)
37.2 (dd, 26,
4)
30.2 (d, 4)
124.0 (s)
(av)
127.9 (s)
2b 125.1
(2 ꢁ s)
127.3 (s) 110.5 (br s, 6) ꢂ20.8
84.6
(s)
64.4 (s)
64.1 (d, 8)
133.0 (d, 6)
129.1 (d, 16)
127.7 (s)
35.5 (d, 24)
29.9 (d, 4)
127.25
(s)
109.3 (br s, 6) (av)
a
Samples in d1-chloroform.
b
D
d (C3a,7a) = d (C3a,7a
(
g
-indenyl complex)) ꢂ d (C3a,7a (g-sodium indenyl)). d (C3a,7a) for sodium indenyl = 130.7 ppm [3].
shifts than those in 2b, suggesting that the structure of 2a places
them in closer proximity to the phenyl groups on the PPh3 and
HPButPh ligands, such that they experience greater ring-current
shielding (or deshielding) effects. In particular, the signal due to
one of the protons on the 5-ring in 2a (H1 or H3 in the numbering
scheme shown in Fig. 2) shows an extreme shift to high field
(d2.70 ppm in d1-chloroform, d 2.81 ppm in d6-benzene), consis-
tent with its proximity to the center of a phenyl ring that lies per-
pendicular to the C–H1/3 bond axis. Similar to what we described
Table 3
Crystallographic data for [(
g
5–indenyl)Ru{PH(tBu)Ph}(PPh3)]ꢃ0.5CH2Cl2 (2).
Formula
Formula weight
Crystal color, habit
Crystal dimensions (mm)
Crystal system, space group
C37.5H38Cl2P2Ru
722.59
orange plate
0.45 ꢁ 0.37 ꢁ 0.07
orthorhombic, Pbcn (no. 60)
a (Å)
b (Å)
c (Å)
V (Å3)
Z
24.5725 (8)
19.1823 (7)
14.9657 (5)
7054.2 (4)
previously for the complexes [Ru(g
5-indenyl)Cl(PR2H)(PPh3)],
8
where R = Cy or Ph [1], we observe broadening of many of the aro-
Dcalcd (g cmꢂ3
)
1.361
0.711
matic signals due to PPh3 in the room temperature 1H and
l
(mmꢂ1
)
13C{1H}) NMR spectra of mixtures of 2a and 2b. This arises from
Diffractometer
Radiation (k [Å])
Bruker D8/APEX II CCDa
(
graphite-monochromated Mo Ka
(0.71073)
–100
55.02
the combination of slowed rotation around the Ru–PPh3 bond
(due to steric congestion at ruthenium) and disparate chemical
environments experienced by each of these three phenyl groups.
The peak broadening is typically exacerbated for congested struc-
tures in which one PPh3 phenyl group points directly toward the
indenyl 6-ring, with particularly pronounced chemical shift disper-
sion being observed for Hortho, Cipso, and Cortho in the 1H and 13C{1H}
spectra. The degree of broadening we observe for aromatic peaks
due to 2a, relative to those due to 2b, suggests that the PPh3 chem-
ical shift dispersion is more pronounced for 2a than for 2b, which
may indicate the PPh3 is closer to the 6-ring of the indenyl ligand
and/or to the P–H group on the HPButPh ligand in 2a.
Temperature (°C)
Data collection 2hmax (°)
Total data collected
60089 (-31 6 h 6 31, -24 6 k 6 24, -
19 6 l 6 19)
8127 (0.0284)
7014
Independent reflns (Rint
Observed reflections
[F2o P 2
)
r
ðF2o Þ]
Structure solution method
Patterson/structure expansion (DIRDIF
2008b)
-
Refinement method
Full-matrix least-squares on F2 SHELXL-97c)
(
Absorption correction method
Range of transmission factors
Data/restraints/parameters
Goodness-of-fit (GOF) (S) (all
data)d
Gaussian integration (face-indexed)
0.9519–0.7416
8127/0/374
1.050
3.3. Assignment of relative stereochemistries in diastereomers 2a and
2b
R1 [F2o P 2
r
ðF2o Þ]e
0.0269
wR2 (all data)f
0.0669
Largest diff peak, hole (e Åꢂ3
)
0.436, ꢂ0.662
The recrystallization described in Section 3.1 gave us crystals of
2 suitable for analysis by X-ray diffraction. The resulting molecular
structure is shown in Fig. 3, along with a simplified drawing to
indicate the relative stereochemistries at Ru and the secondary
phosphine. The P–H group of the secondary phosphine (H1P) lies
approximately anti to the Ru–indenyl bond (Ru–C⁄) along the
P1–Ru bond, which allows the Ph and But groups on the secondary
phosphine to achieve maximum distance from the PPh3 phenyl
rings.5 These two groups lie on opposite sides of the plane contain-
ing H1P, P1, Ru, and C⁄, which bisects the indenyl ring and also con-
tains H2. Relative to this plane, the phenyl group of the secondary
phosphine is on the same ‘‘side’’ as the Cl ligand on Ru, while the
But group is on the same side as the PPh3 ligand.
a
Programs for diffractometer operation, unit cell indexing, data collection, data
reduction and absorption correction were those supplied by Bruker.
b
P.T. Beurskens, G. Beurskens, R. de Gelder, S. Garcia-Granda, R. Israel, R.O. Gould,
J.M.M. Smits, The DIRDIF-99 Program System, Crystallography Laboratory, University
of Nijmegen, The Netherlands, 1999.
c
G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
S = [R
w(F2o ꢂ F2c )2/(n ꢂ p)]1/2 (n = number of data; p = number of parameters
d
varied; w = [r
2(Fo2) + (0.0304P)2 + 3.9411P]ꢂ1 where P = [Max(Fo2, 0) + 2F2c ]/3).
e
R1
wR2 = [
=
R
||Fo| ꢂ |Fc||/
R|Fo|.
R
w(F2o ꢂ F2c )2/
R .
w(F4o )]1/2
f
the plane of symmetry bisecting the indenyl ligand: accordingly
we see seven distinct signals for H1–H7 for both isomers. The
sharpness of these signals indicates that rotation about the
Ru–indenyl bond is either very fast or very slow on the NMR time-
scale; we suspect the former, based on the four sharp indenyl pro-
ton signals we observe for the more symmetric, but comparably
sterically crowded, parent complex 1. Peaks due to the protons
on the indenyl 5- and 6-rings in 2a show more disperse chemical
Comparison of the solution 1H NOESY NMR correlations for the
diastereomer mixture (see Supporting Information) to the solid
state structure shown in Fig. 3 allows us to propose an assignment
5
Similar to what we reported in Ref. [1] for the symmetrically substituted
analogues of 2, the crystallographic and IR data obtained for 2 provide no evidence for
hydrogen bonding between the secondary phosphine P–H and the Ru–Cl.

G.L. Gibson et al. / Inorganica Chimica Acta 369 (2011) 133–139
137
2a
2a
2b
2b
15 min
1
3 days
9 days
ppm
90
80
70
60
50
Fig. 1. 121.49 MHz 31P{1H} NMR spectra of a mixture of 2a and 2b in d6-benzene in a J. Young sealable NMR tube at room temperature (a small amount of residual PPh3
(ꢂ5 ppm) apparently reacts with 2 to give a small amount of 1 (47 ppm), which is in equilibrium with 2. Ultimately this excess PPh3 is completely converted to O@PPh3
(26 ppm) by reaction with trace oxygen in the sample.).
of the distinct spectra for 2a and 2b to structures of defined rela-
tive stereochemistry. For both isomers, signals due to the P–H
groups show correlation with PPh3 signals but not with any signals
due to indenyl protons. (The P–H group for 2b also shows a corre-
lation with signals due to the P–H group of the secondary phos-
phine.) This supports a solution conformation for both isomers
that conserves, at least approximately, the anti relationship of
the P–H and Ru–indenyl bonds, as observed in the solid state struc-
ture. Thus the secondary phosphine Ph and But substituents must
phosphine Ph and PPh3 signals (presumably Hortho). The H2 signal
for 2a shows correlations with the But and PPh3 signals and a weak
correlation with the secondary phosphine Ph signal. For 2b, the
downfield H1/3 signal correlates with signals due to PPh3 and cor-
relates weakly to the But signal, while the upfield H1/3 signal cor-
relates with signals due to the secondary phosphine Ph and
correlates weakly to the But signal. The H2 signal for 2b shows cor-
relations with signals due to all three of the But, secondary phos-
phine Ph, and PPh3 groups. Based on these correlations, which
establish the relative positions of the secondary phosphine Ph
and the PPh3 ligand on either ‘‘side’’ of the indenyl ring for both
isomers, we propose that the relative stereochemistry we observe
in the solid state structure corresponds to the structure of 2b,6 in
which the secondary phosphine Ph lies toward the Cl side of the mol-
sit ‘‘up’’ toward the
g
5-indenyl ligand in both isomers, with one
pointing to the same side as the Cl ligand and the other pointing
toward the side of the PPh3 ligand. NOESY correlations for the inde-
nyl H1 and H3 signals (which are well separated in the spectra of
both isomers) are therefore quite diagnostic of the stereochemistry
at the secondary phosphine, since one of H1 and H3 must point to
the PPh3 side of the complex and the other must point toward the
Cl side of the complex. As illustrated in Fig. 4, for 2a the downfield
H1/3 signal shows a correlation only with the But signal, while the
upfield H1/3 signal shows correlations with both secondary
6
The solution structure of 2b has a slightly different conformation from the solid
state structure: in the NOESY spectrum we see weak correlations of both H1 and H3
with the But protons, which are consistent with a minimum H1–But distance of
2.848 Å (H1–H19B) but not with a minimum H3–But distance of 4.431 Å (H3–H19A).

138
G.L. Gibson et al. / Inorganica Chimica Acta 369 (2011) 133–139
the molecule is particularly rich in aromatic groups relative to the
other side.
7
4
1
3
7a
3a
6
5
2
4. Conclusion
The utility of chiral-at-metal complexes in studying the reaction
mechanisms of transition metal complexes, and their potential for
introducing stereocontrol in catalytic systems, has been well-
established by Brunner and others, and chiral ruthenium half-
sandwich complexes have played a large role in the development
of this field [5]. Complex 2 represents an important new example
of a relatively configurationally stable system undergoing epimer-
ization at rates that will allow mechanistic study by NMR. It is also
an unusual example of diastereoisomerism involving the metal
coordination of (racemic mixtures) of P-chiral secondary phos-
phines [6], of relevance to the increasing interest in stereoselective
synthesis of P-chiral phosphine ligands via catalytic P–C bond-
forming reactions [7]. In this context, we are currently studying
the base-promoted dehydrohalogenation of complex 2; prelimin-
ary experiments confirm the formation of stereoisomers of the
Fig. 2. Numbering system used for the indenyl ligand.
corresponding terminal phosphido complex [Ru(g
5-indenyl)-
(@PButPh)(PPh3)]7 (3, 30 in a 1:7 ratio), which exhibit the diagnostic
deep blue color of these 5-coordinate complexes [2c] and are rela-
tively stable at room temperature in solution (ꢀh).8 We will report
more on these results in due course.
Acknowledgment
We thank the Natural Sciences and Engineering Research Coun-
cil (NSERC) of Canada for funding.
Ru
But
Appendix A. Supplementary material
Ph3P
P
Ph
Cl
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2010.12.058.
H
Fig. 3. Molecular structure of 2, assigned as 2b. Non-hydrogen atoms are
represented by Gaussian ellipsoids at the 20% probability level. The hydrogen
atom attached to P1 is shown with an arbitrarily small thermal parameter; all other
hydrogens are not shown. Selected interatomic distances (Å) and bond angles (deg)
(C⁄ denotes the centroid of the plane defined by C(7A)–C(1)–C(2)–C(3)–C(3A)):
Ru–P(1) = 2.2618(5), Ru–P(2) = 2.3242(4), Ru–Cl = 2.4366(4), Ru–C⁄ = 1.895, P(1)–
H(1P) = 1.292(18); P(1)–Ru–P(2) = 97.941(16), P(1)–Ru–Cl = 81.610(15), P(2)–Ru–
Cl = 87.346(14), P(1)–Ru–C⁄ = 125.2, P(2)–Ru–C⁄ = 126.1, Cl–Ru–C⁄ = 125.6. Indenyl
References
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7
31
2
202.5 MHz P{1H} data (d) for 3 and 30 in d6-benzene: (3) 257.7 (d, JPP = 60 Hz,
PButPh), 61.5 (d, PPh3); (30) 253.3 (d, JPP = 60 Hz, PButPh); 60.7 (d, PPh3).
2
ecule, while for 2a the secondary phosphine Ph lies toward the PPh3
side of the molecule. This latter relative stereochemistry is consis-
tent with the extreme 1H chemical shift dispersion we observe for
both the indenyl protons and the PPh3 protons, since one side of
8
Decomposition in solution leads principally to the products of orthometallation
[2c], 4 and 40, in a 1:1.3 ratio. 121.5 MHz P{1H} data (d) for 4 and 40 in d6-benzene:
31
(4) 83.4 (d, JPP = 26 Hz, HPButPh), ꢂ18.6 (d, PPh2C6H4); (40) 76.6 (d, JPP = 29 Hz,
2
2
HPButPh); ꢂ21.4 (d, PPh2C6H4).

G.L. Gibson et al. / Inorganica Chimica Acta 369 (2011) 133–139
139
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