Synthesis and characterization of a series of rhodium, iridium, and ruthenium isocyanide complexes

Article abstract of DOI:10.1016/j.ica.2013.07.039

Several new electrophilic metal isocyanide complexes have been fully characterized and reported herein. Isocyanide induced cleavage of the dimer, [LMCl₂]₂ {LM = Cp^{a? -}Ir, Cp ^{a? -}Rh, or (p-cymene)Ru}, with 2,6-xylylisocyanide or 2,6-diethylphenylisocyanide produces complexes of the general formula LM(CNAr)Cl₂. Halide metathesis of the dichloro complexes with sodium iodide produces the corresponding complexes with the general formula LM(CNAr)I₂. For the analogous ruthenium complexes better results were achieved via isocyanide induced cleavage of [(p-cymene)RuI₂] ₂ and was synthesized differently from previous reports. Several neutral complexes in reaction with AgPF₆ in acetonitrile form cationic, solvent-coordinated complexes have been fully characterized. Most reactions with rhodium decomposed to either [Cp ^{a? -}RhCl(MeCN)]₂[(PF₆)₂] starting from the dichloro complexes, or [Cp ^{a? -}Rh(MeCN)₃,(PF₆)₂] and Cp^{a? -}Rh(CNAr)I₂ starting from the diiodo complexes. Several bases were probed to see if cyclization could be induced, but were not successful in any case. Many of these complexes have been characterized by single crystal X-ray crystallography.

Full text of DOI:10.1016/j.ica.2013.07.039

Inorganica Chimica Acta 407 (2013) 131–138
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis and characterization of a series of rhodium, iridium,
and ruthenium isocyanide complexes
⇑
Aaron P. Walsh, William W. Brennessel, William D. Jones
Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 May 2013
Received in revised form 16 July 2013
Accepted 18 July 2013
Available online 8 August 2013
Several new electrophilic metal isocyanide complexes have been fully characterized and reported herein.
Isocyanide induced cleavage of the dimer, [LMCl2]2 {LM = Cp⁄Ir, Cp⁄Rh, or (p-cymene)Ru}, with 2,
6-xylylisocyanide or 2,6-diethylphenylisocyanide produces complexes of the general formula
LM(CNAr)Cl2. Halide metathesis of the dichloro complexes with sodium iodide produces the correspond-
ing complexes with the general formula LM(CNAr)I2. For the analogous ruthenium complexes better
results were achieved via isocyanide induced cleavage of [(p-cymene)RuI2]2 and was synthesized differ-
ently from previous reports. Several neutral complexes in reaction with AgPF6 in acetonitrile form cat-
ionic, solvent-coordinated complexes have been fully characterized. Most reactions with rhodium
decomposed to either [Cp⁄RhCl(MeCN)]2[(PF6)2] starting from the dichloro complexes, or [Cp⁄-
Rh(MeCN)3,(PF6)2] and Cp⁄Rh(CNAr)I2 starting from the diiodo complexes. Several bases were probed
to see if cyclization could be induced, but were not successful in any case. Many of these complexes have
been characterized by single crystal X-ray crystallography.
Keywords:
Rhodium
Iridium
Ruthenium
Isocyanide
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
and Ellman [26–31] describes the broadening scope, utility, and
understanding of carboxylate-assisted C–H bond functionaliza-
C–H bond functionalization via homogenous transition metal
complexes has become an attractive approach in the synthesis of
industrial & medicinally relevant compounds, especially synthesis
and embellishment of heterocyclic compounds which are com-
monly found in natural products and drug molecules [1–4]. Func-
tionalization of C–H bonds constitutes a more efficient synthetic
tool avoiding pre-activated substrates, harsh reaction conditions,
and disposal of toxic by-products and waste. For the past few dec-
ades, studies in C–H bond activation via transition metals has
shown promising developments towards activating ‘difficult’ C–H
bonds including (sp3)C–H bonds [5–14]. Successful applications
of C–H functionalization stem from a thorough mechanistic under-
standing of the C–H bond metalation based upon the nature of the
active metal species.
For late transition metals C–H bond activation can occur via two
pathways. The commonly employed oxidative addition in which an
electron rich metal fragment inserts into a C–H bond, or electro-
philic activation with an electron poor metal species assisted by
a Lewis-basic ligand such as a carboxylate [15–18]. Specifically car-
boxylate-assisted electrophilic C–H activation has become a very
powerful protocol due to the mild conditions and stability of orga-
nometallic intermediates making for an easily studied system [19].
Significant work done by Fagnou [16,20,21], Ackermann [22–25],
tions. Our group has developed and exploited a few procedures
via electrophilic activation using [Cp⁄MCl2]2 [M = Ir (1); Rh (2)] to
stoichiometrically synthesize polycyclic isoquinoline salts [32]
and probe the mechanism and selectivity of these cyclometalla-
tions [33]. Furthermore, the reactivity of cyclometalated interme-
diates with small molecules and regioselectivity of the insertion
has been studied [34].
Recently we have also shown competent H/D exchange with
novel electrophilic rhodium and iridium complexes possessing a
fac-chelating bis-pyrazolylacetate ligand with benzene and other
substituted arenes [35]. Similarly studies with Tp0Ir (Tp0 = hydro-
tris(3,5-dimethylpyrazolyl)borate) [36–38] and one case with 1
[39] show benzylic C–H activation via iridium(III). With these
precedents we wanted to explore the potential reactivity of 1
and 2 with aryl isocyanides such as 2,6-xylyl isocyanide, in which
electrophilic activation of a benzylic (sp3)C–H bond followed by
cyclization could lead to indole products, as seen earlier with
ruthenium(0) (Fig. 1) [40,41].
2. Results and discussion
2.1. Synthesis and characterization of metal aryl isocyanide complexes
2.1.1. Synthesis and characterization of Cp⁄M(CNAr)Cl2 complexes
The dichloro complexes are easily produced starting from the
rhodium or iridium bridging halide dimers (1 or 2) in combination
⇑
Corresponding author. Tel.: +1 585 275 5493.
E-mail address: jones@chem.rochester.edu (W.D. Jones).
0020-1693/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2013.07.039

132
A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
vented by first performing the iodide metathesis on 1 or 2 under
the same conditions to obtain the [Cp⁄MI2]2 compound. The diio-
do-dimer can then be cleaved by addition of an isocyanide yielding
the same diiodo complexes.
Fig. 1. Proposed tandem electrophilic C–H activation/cyclization.
2.1.3. Synthesis and characterization of (p-cymene)Ru(CNAr)Cl2
complexes
By simple extension to the group 9 complexes the p-cymene
ruthenium complexes were made accordingly by adding a stoichi-
with a stoichiometric amount of aryl isocyanide producing bench
stable, monomeric Cp⁄M(CNAr)Cl2 [Ar = xylyl or 2,6-diethylphenyl
(0)] in good to excellent yields similar to previously reported syn-
theses (Eq. (1)) [42–44].
ometric amount of aryl isocyanide to
a solution of [(p-
cymene)RuCl2]2 (3) in dichloromethane (Eq. (4), X = Cl). Several
modifications to the synthesis of the ruthenium complexes were
necessary. Reactions performed under identical conditions to the
group 9 complexes gave low yields. The solubility of 3 in THF is
poor, as is the solubility of the isocyanide complexes. CH2Cl2
proved to be a better solvent for the reaction, and the reaction
times were greatly extended to ensure complete coordination of
the isocyanide. 1H NMR and IR spectral data for these complexes
are summarized in Table 2.
As noted previously with the group 9 complexes, the changes in
the spectral data for the ruthenium complexes behave similarly.
The p-cymene resonances are affected by the halogen bound to
the metal and the effect on the isocyanide is more noticeable via
IR than by 1H NMR spectroscopy. For the ruthenium complexes
bearing the 2,6-xylyl isocyanide, the C„N stretching frequency ap-
pears in between that of the analogous iridium and rhodium com-
plexes. However, when looking at the complexes bearing 2,6-
diethylphenyl isocyanide, the C„N stretching frequency is lower
in energy than in the iridium complexes.
½CpꢀMCl2ꢁ þ 2 eqv: CNAr ! CpꢀMðCNArÞCl
ð1Þ
2
2
The crude products are typically orange for iridium complexes
and red for the corresponding rhodium complexes. NMR and IR
spectral data for these complexes are summarized in Table 1. Some
features are worth pointing out in the spectra. First, the shift for
the Cp⁄ resonance depends on the combination of the metal and
the halogen while the resonances for the isocyanide are largely
unaffected by either. Second, in the 13C{1H} spectra, the isocyanide
carbon bound to the metal is difficult to observe due to coupling to
the quadrupolar nitrogen and the metal center. The ipso carbon of
the isocyanide which is also coupled to nitrogen is also not ob-
served. The IR spectra of these complexes are typical in that the
C„N stretching frequency appears in the range 2100–2200 cmꢂ1
.
The C„N stretching frequencies are of lower energy in the iridium
complexes in comparison to the rhodium analogs overall, but the
energy is greater than observed in the free isocyanide
(2120 cmꢂ1), implying little
either metal.
p-backbonding upon coordination to
2.1.4. Synthesis and characterization of (p-cymene)Ru(CNAr)I2 and
alternative synthesis of [(p-cymene)RuI2]
2.1.2. Synthesis and characterization of Cp⁄M(CNAr)I2 complexes
The diiodo complexes are made via halide metathesis in reflux-
ing THF in the presence of a 10-fold excess of sodium iodide. While
the dichloro complexes are not entirely soluble in THF, once the so-
dium iodide is added the color darkens, more prominently for rho-
dium complexes than iridium. Rhodium complexes become dark
maroon, while the iridium complexes are a darker orange (Eq. (2)).
The halide metathesis used for the group 9 complexes can ex-
tended to include the analogous ruthenium complexes. Similar
problems arose where the [(p-cymene)RuI2]2 dimer (30) would
form under prolonged reaction times. Since all of the complexes
have similar solubility, purification of the complexes after synthe-
sis is not straightforward. Rather, it is more feasible for the ruthe-
nium complexes to synthesize them via isocyanide-induced
cleavage of 30 (Eqs. (3) and (4)) [45–48]. The reaction time for
the diiodo analogs was greatly extended to ensure complete coor-
dination of the isocyanide. Characterization of these compounds
was straightforward, with the p-cymene resonances being slightly
de-shielded in comparison to the dichloro compounds. More nota-
bly, the IR for these compounds shows that the C„N stretch of the
2,6-xylyl isocyanide is between that of the corresponding iridium
and rhodium complexes, but for 2,6-diethylphenyl isocyanide the
C„N stretch is lower in energy than the in related iridium
compound.
CpꢀMðCNArÞCl2 þ 2 eqv: Nal ! CpꢀMðCNArÞCl2
þ 2 eqv:NaCl
ð2Þ
Both the IR and 1H NMR spectra of the diiodo complexes are
similar to the dichloro complexes but the Cp⁄ methyl resonances
become more de-shielded and the stretching frequencies of the
C„N bond become lower in energy (Table 1). In some cases NMR
spectral analysis of the product from the metathesis reactions
shows the presence of another Cp⁄ peak that corresponds to the
iodo version of the starting dichloro-dimer. This can be circum-
Table 1
1H NMR and IR spectral data for complexes 1a, 1b; 2a, 2b; 1a0, 1b0; 2a0, 1b0.
Complex
1H NMR resonances,a
d
IRc (solid), cmꢂ1
Cp⁄
CNAr
Cp⁄IrCl2(CN-2,6-Xyl) (1a)
1.86 (s)
1.85 (s)
2.14 (s)
2.17 (s)
1.85 (s)
1.84 (s)
2.14 (s)
2.16 (s)
7.16 (m, 1H)7.09 (d, 2H)2.45 (s, 6H)
7.2 (m, 1H)7.1 (d, 2H)2.47 (s, 6H)
7.12 (m, 3H)2.5 (s, 6H)
7.16 (m, 1H)7.08 (d, 2H)2.5 (s, 6H)
7.24 (m, 1H)7.11 (d, 2H)2.82 (q, J = 7.6, 7.2 Hz, 4H)1.26 (t, J = 7.6 Hz, 6H)
7.28 (m, 1H)7.12 (d, 2H)2.84 (q, J = 7.6, 7.2 Hz, 4H)1.27 (t, J = 7.6 Hz, 6H)
7.21 (m, 1H)7.12 (d, 2H)2.87 (q, J = 7.6, 7.2 Hz, 4H)1.27 (t, J = 7.6 Hz, 6H)
7.23 (m, 1H)7.1 (d, 2H)2.86 (q, J = 7.6, 7.2 Hz, 4H)1.27 (t, J = 7.6 Hz, 6H)
2154
2172d
2133d
2150d
2158
2173
2150
2163
Cp⁄RhCl2(CN-2,6-Xyl)b (2a)
Cp⁄IrI2(CN-2,6-Xyl)b (1b)
Cp⁄RhI2(CN-2,6-Xyl)b (2b)
Cp⁄IrCl2(CN-2,6-Et2C6H3) (1a0)
Cp⁄RhCl2(CN-2,6- Et2C6H3) (2a0)
Cp⁄IrI2(CN-2,6- Et2C6H3)(1b0)
Cp⁄RhI2(CN-2,6- Et2C6H3)(2b0)
a
b
c
CDCl3 solvent, 25 °C.
Previously reported in C6D6.
Reference values (ATR): 2,6-xylyl isocyanide, 2120 cmꢂ1; 2,6-diethylphenyl isocyanide, 2114 cmꢂ1
Previously reported in KBr pellet.
.
d

A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
133
Table 2
1H NMR and IR spectral data for complexes 3a, 3b; 3a0, 3b0.
Complex
1H NMR resonances,a
p-cymene
d
IR (solid), cmꢂ1
CNAr
(p-cymene)RuCl2(CN-2,6-Xyl) (3a)
(p-cymene)RuI2(CN-2,6-Xyl) (3b)
(p-cymene)RuCl2 (CN-2,6- Et2C6H3) (3a0)
5.69 (d, J = 6 Hz, 2H)5.52 (d, J = 6 Hz, 2H)2.91
(sept, J = 6.8 Hz, 1H)2.33 (s, 3H)1.31 (d, J = 6.8 Hz, 6H)
5.74 (d, J = 6 Hz, 2H)5.6 (d, J = 6 Hz, 2H)3.06
(sept, J = 6.8 Hz, 1H)2.61 (s, 3H)1.32 (d, J = 6.8 Hz, 6H)
5.69 (d, J = 6 Hz, 2H)5.52 (d, J = 6 Hz, 2H)2.93
(sept, J = 6.8 Hz, 1H)2.33 (s, 3H)1.32 (d, J = 6.8 Hz, 6H)
7.15 (m, 1H)7.07 (d, 2H)2.45(s, 6H)
2164
2144
2154
7.11 (m, 1H)7.06 (d, 2H)2.51 (s, 6H)
7.25 (m, 1H)7.11 (d, 2H)2.84
(q, J = 7.6, 7.2 Hz, 4H)1.32
(t, J = 7.6 Hz, 6H)
(p-cymene)RuI2(CN-2,6- Et2C6H3)(3b0)
CDCl3 solvent, 25 °C.
5.74 (d, J = 6 Hz, 2H)5.6 (d, J = 6 Hz, 2H)3.08
(sept, J = 6.8 Hz, 1H)2.6 (s, 3H)1.32 (d, J = 6.8 Hz, 6H)
7.2 (m, 1H)7.1 (d, 2H)2.88
(q, J = 7.6, 7.2 Hz, 4H)1.27 (t, J = 7.6 Hz, 6H)
2141
a
Table 3
1H NMR and IR spectral data for cationic solvent complexes of 1a, 1b, 1a0, 1b0.
Complex
1H NMR resonances,a,b
d
IRc (solid), cmꢂ1
Cp⁄
CNAr
[Cp⁄IrCl(MeCN)(CN-2,6-Xyl)]PF6 (1a[PF6])
[Cp⁄IrI(MeCN)(CN-2,6-Xyl)]PF6 (1b[PF6])
[Cp⁄IrCl(MeCN)(CN-2,6- Et2C6H3)]PF6(1a0[PF6])
[Cp⁄IrI(MeCN)(CN-2,6- Et2C6H3)]PF6(1b0[PF6])
[Cp⁄RhI(MeCN)(CN-2,6-Xyl)]PF6 (2b[PF6])
1.88 (s)
2.04 (s)
1.89 (s)
2.04 (s)
2.02 (s)
7.34 (m, 1H)7.27 (d, 2H)2.45(s, 6H)
7.32 (m, 1H)7.26 (d, 2H)2.48 (s, 6H)
7.42 (m, 1H)7.29 (d, 2H)2.82 (q, J = 7.6, 7.2 Hz, 4H)1.26 (t, J = 7.6 Hz, 6H)
7.39 (m, 1H)7.28 (d, 2H)2.85 (q, J = 7.6, 7.2 Hz, 4H)1.26 (t, J = 7.6 Hz, 6H)
7.34 (t, 1H)7.28 (d, 2H)2.48(s, 6H)
2327, 2185
2324, 2176
2332, 2183
2331, 2175
2326, 2182
a
b
c
CD3CN solvent, 25 °C.
Methyl peak for coordinated acetonitrile is d 1.96 for each complex.
Reference value (ATR): acetonitrile, 2253 cmꢂ1
.
½ðp-cymeneÞRuCl2ꢁ2 þ 4 eqv: Nal ! ½ðp-cymeneÞRuCl2ꢁ2
þ 4 eqv: NaCl
unstable in solution and disproportioned faster than crystallizing.
On a few occasions a new rhodium dimer was isolated and charac-
terized as [Cp⁄RhCl(MeCN)]2[PF6]2 (4) but no [Cp⁄RhCl(CNAr)2]PF6
was ever isolated. Ruthenium compounds, other than 3b[PF6], were
never isolated as solids and crystallization of this ruthenium com-
plex required several days at ꢂ30 °C. The long crystallization period
was also seen for the rhodium iodo-solvent complex, 2b0[PF6], but
attempts to isolate the target molecule resulted in isolation of
either [Cp⁄Rh(MeCN)3,PF6]2 (5), which was characterized by X-ray
diffraction, or the starting material, 2b0 [49]. Even though isocya-
ð3Þ
ð4Þ
½ðp-cymeneÞRuCl2ꢁ2 þ 2 eqv: CNAr
! 2 eqv:ðp-cymeneÞRuðCNArÞI2
2.2. Synthesis and characterization of cationic metal acetonitrile
complexes
nides are strong
r-donor ligands they are labile, and this observa-
Attempts to induce C–H activation/cyclization were first made
with silver acetate to abstract the halogen from a complex and
generate the open site necessary for acetate-assisted C–H activa-
tion. While halogen abstraction occurred readily, C–H activation
was not observed (vida infra). Isolation of the intermediate cationic
species proved unfeasible with acetate as a counter-ion, but ex-
change for a bulky counter-ion such as hexafluorophosphate al-
tion could be extended to the ruthenium complexes as well as
their isolations and/or crystallizations were not routine.
2.3. X-ray crystallography
2.3.1. Neutral complexes
lowed for isolation and crystallization. Slow addition of
a
X-ray quality crystals for neutral complexes were grown, typi-
cally, by vapor diffusion of pentane into a concentrated solution
of either dichloromethane or chloroform. Decent crystals could
also be grown by simple evaporation of the solution overnight.
The observed water and oxygen stability allows for several crystal-
lization methods utilizing readily accessible solvents. Table 4 de-
scribes selected bonds and angles and Table 7 describes selected
parameters of the X-ray diffraction experiments.
solution of AgPF6 in dry acetonitrile to a solution of the neutral di-
halo complex in dry acetonitrile under an atmosphere of nitrogen
produces the solvent trapped cationic metal complex in moderate
to good yields. Precipitation of the product occurs upon adding ex-
cess diethyl ether to a concentrated solution following filtration of
the silver halide by-product. 1H NMR and IR spectral data for these
complexes are summarized in Table 3.
Interestingly, in the iridium and rhodium iodo-solvent com-
plexes, the Cp⁄ resonances are significantly more shielded upon
removing the halide and coordinating an acetonitrile molecule. As
stated previously the carbene carbon of the isocyanide is unobserv-
able in the 13C{1H} NMR spectrum and the nitrile carbon of acetoni-
All structures obtained are tetrahedral-like ‘piano-stools’ and
similar to each other in most aspects as seen in Table 4. The geo-
metrical variations are statistically insignificant. The isocyanide
bond length is nearly unaffected upon coordination of M3+ center
in comparison to the free isocyanide (1.161 Å) [50], consistent with
trile is also not observed for similar reasons. The v (C„N) stretching
minimal p-back bonding and the isocyanide acting purely as a r-
frequencies are particularly more affected by the halide abstraction
than are the changes in chemical shifts in the NMR spectra. Each
complex shows an increase in energy for the C„N bond stretch of
about 30 cmꢂ1 while the stretch corresponding to the acetonitrile
bond is relatively unchanged in all of the complexes. The analogous
rhodium and ruthenium mono-chlorides were never isolated. The
rhodium chloride compounds subjected to these conditions were
donor. However, 1a does have a significant amount of C–N–Ar
bending (168°), comparable to that seen in the previously reported
1b (166°). 2b is isostructural and has a C„N–Ar angle of ꢃ167°.1
1
An isomorph was crystallized via layering hexane on a concentrated solution in
DCM: a = 8.689(3) Å, b = 31.360(9) Å, c = 22.961(7) Å;
a = 90°, b = 97.216(4)°, c = 90°.
The full report is in the SI.

134
A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
Table 4
Selected distances and angles for neutral complexes.
Compound
C„N length (Å)
M–CN length (Å)
M–C„N angle (°)
C„N-Ar angle (°)
Ave. p-stacking distance (Å)
1a
1.157(3)
1.154(4)
1.161(3)
1.1582(18)
1.161(2)
1.1562(17)
1.160(2)
1.155(2)
1.161(3)
1.159(3)
1.162(4)
1.932(3)
1.923(3)
1.913(3)
1.9675(14)
1.9385(18)
1.9582(13)
1.9340(18)
1.9617(19)
1.942(2)
176.0(2)
177.3(3)
176.4(2)
168.4(3)
177.0(4)
172.2(3)
170.07(14)
166.96(18)
173.71(14)
173.59(18)
176.8(2)
3.74–3.86a
3.50–3.63a
3.37–3.39
3.74–3.88a
-
1a0
1b0
2a
173.86(12)
179.03(16)
174.97(12)
177.46(16)
177.77(17)
176.69(19)
175.55(18)
178.1(3)
2b
2a0
2b0
3a
3b
3a0
3b0
-
3.30–3.37
3.45–3.53
3.62–3.75
3.37–3.45
3.47–3.49
177.2(2)
171.9(2)
173.5(3)
1.952(2)
1.940(3)
a
Average distance for T-stacking of Cp⁄ methyl to isocyanide arene ring of adjacent molecule.
3b’
3b
3a’
Fig. 2. Intermolecular
p
-stacking displayed in the crystal structures of 3a0, 3b, and 3b0. Thermal ellipsoids are drawn at the 50% probability level. The asymmetric unit’s
displayed are doubled. Hydrogen atoms were removed for clarity.
Table 5
Table 6
Selected distances and angles for cationic complexes of isocyanide.
Selected distances and angles for cationic complexes of acetonitrile.
Compound C„N
M–CN
length
(Å)
M–C„N
angle (°)
C„N-Ar
angle (°)
Ave. p-
stacking
distance (Å)
Compound MeC„N
M–NCMe
length (Å)
M–N„CMe
angle (°)
N„C–Me
angle (°)
length
(Å)
length (Å)
1a[PF6]
1b[PF6]
1a0[PF6]
1b0[PF6]
2b[PF6]
1.139(3)
1.137(3)
1.138(5)
1.135(5)
1.135(5)
2.063(2)
2.058(2)
2.050(3)
2.052(3)
2.084(3)
168.4(2)
168.5(2)
171.3(3)
173.1(3)
169.0(3)
179.0(3)
178.0(3)
178.6(5)
179.5(5)
177.5(4)
1a[PF6]
1b[PF6]
1a0[PF6]
1b0[PF6]
2b[PF6]
1.150(3) 1.955(3)
1.158(3) 1.952(2)
1.156(6) 1.955(5)
1.163(5) 1.958(4)
1.158(4) 1.975(3)
178.6(2)
179.5(2)
177.5(5)
176.8(4)
179.7(3)
175.9(3)
175.4(2)
175.2(5)
174.9(5)
175.9(3)
3.44–3.45
3.47–3.48
3.42–3.43
3.51–3.52
3.50–3.51
2.3.2. Cationic complexes
The analogous ruthenium compound 3a is unique in comparison to
the group 9 compounds with a space group of P21/n while 1a and 2a
are C2/c. While most of the complexes have only one molecule in the
asymmetric unit, complexes 3b, 3a0, and 3b0 have two independent
molecules in the asymmetric unit (Fig. 2). Other than compounds
1a, 1a0, 2a, 2a0, and 2b, many of the structures display characteristic
Crystallization of these cationic complexes was also done via
vapor diffusion of diethyl ether into a concentrated solution of
the crude material in acetonitrile. The 2,6-xylylisocyanide coordi-
nated complexes would crystallize overnight at room temperature
under a nitrogen atmosphere while the 2,6-diethyphenyl isocya-
nide complexes took several days at ꢂ30° to crystallize. Structural
analysis of these cationic complexes shown that the C„N–Ar angle
became more linear compared to the neutral precursors. Table 5
shows selected bond lengths and angles for the cationic complexes
for the isocyanide ligand and Table 6 shows structural information
for the acetonitrile ligand. These complexes can be considered ‘chi-
ral-at-metal’ as there are four distinct ligands attached to one me-
tal center that is of tetrahedral geometry. However, all of these
cationic compounds crystallized in the centrosymmetric space
p-stacking within a commonly accepted range of 3.3–3.8 Å [51]. The
measured distance ranges can be seen in Table 4. Structures 1a, 1a0,
and 2a exhibit T-stacking between a methyl group from a coordi-
nated Cp⁄ to the arene ring of an isocyanide on an adjacent molecule.
Otherwise, all rhodium structures were isostructural with the anal-
ogous iridium structures. The ruthenium structures were unique
from the group 9 complexes and also from each other. 3a packed
in a P21/n space group and had only one molecule in the asymmetric
unit. The other 3 ruthenium structures, 3b, 3a0, and 3b0, which had
ꢀ
group P1 as a pair of enantiomers. All of the cationic complexes
ꢀ
crystallized in the P1 space group, are not isostructural to 3a.
crystallized display characteristic
p-stacking and the measured

A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
135
Table 7
Summary of crystallographic data for complexes.
Parameter
3b
3a0
3b0
1a[PF6]
1b[PF6]
1a0[PF6]
1b0[PF6]
2b[PF6]
Empirical formula
Formula weight
Crystal System
Space group
a (Å)
C
19H23I2NRu
C21H27Cl2NRu
465.41
C21H27I2NRu
648.30
C21H27ClF6IrN2P
680.06
C21H27F6IIrN2P
771.51
C23H31ClF6IrN2P
708.12
C23H31F6IIrN2P
799.57
C21H27F6IN2PRh
682.22
620.25
triclinic
P1
triclinic
triclinic
triclinic
triclinic
triclinic
triclinic
triclinic
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
P1
P1
P1
P1
P1
P1
P1
7.4768(6)
15.7980(12)
17.9638(14)
72.7420(10)
84.997(2)
89.865(2)
2018.0(3)
4
2.042
1.035
R1 = 0.0310
wR2 = 0.0651
R1 = 0.0437
wR2 = 0.0697
7.2867(3)
13.9017(7)
20.7264(10)
77.084(1)
86.611(1)
82.908(1)
2029.68(16)
4
1.523
1.021
R1 = 0.0437
wR2 = 0.0819
R1 = 0.0691
wR2 = 0.0913
7.6913(6)
13.3242(11)
24.663(2)
75.408(2)
85.356(2)
78.374(2)
2223.9(4)
4
1.798
1.034
R1 = 0.0379
wR2 = 0.0781
R1 = 0.0537
wR2 = 0.0830
7.815(3)
9.298(3)
16.848(6)
88.007(7)
81.362(7)
81.701(7)
1197.6(8)
2
1.886
1.061
R1 = 0.0344
wR2 = 0.0656
R1 = 0.0481
wR2 = 0.0694
7.9835(8)
9.3302(9)
16.9294(16)
86.656(2)
80.435(2)
79.976(2)
1224.0(2)
2
2.093
1.051
R1 = 0.0306
wR2 = 0.0587
R1 = 0.0425
wR2 = 0.0621
7.7315(8)
10.9322(12)
15.3788(16)
88.062(2)
89.430(2)
79.906(2)
1279.0(2)
2
1.839
1.014
R1 = 0.0504
wR2 = 0.0874
R1 = 0.0879
wR2 = 0.1030
7.9155(12)
11.2196(16)
15.399(2)
88.1993(3)
88.406(3)
77.583(3)
1334.63
7.9489(8)
9.2454(9)
17.2120(17)
87.143(2)
80.231(2)
81.291(2)
1224.0(2)
2
1.839
1.013
R1 = 0.0486
wR2 = 0.0941
R1 = 0.0930
wR2 = 0.01085
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V(Å3)
Z
2
Dcalc (Mg/m3)
Goodness-of-fit, F2
Final R indices
1.990
1.060
R1 = 0.0448
wR2 = 0.1058
R1 = 0.0724
wR2 = 0.1201
[l > 2r(l)]
R indices
(all data)
Parameter
Empirical formula
Formula weight
Crystal System
Space group
a (Å)
1a
2a
3a
1a0
1b0
C21H28I2IrN
740.44
monoclinic
P21/c
16.5408(17)
8.9938(9)
15.8158(16)
90
2a0
2b0
2b
C
19H24Cl2IrN
C19H24Cl2NRh
440.20
monoclinic
C2/c
22.8732(16)
14.0280(10)
14.2045(10)
90
C20H25Cl4NRu
522.28
monoclinic
P21/n
17.2637(13)
7.1016(5)
19.6517(15)
90
C21H28Cl2IrN
557.54
monoclinic
P21/c
8.3293(9)
14.9714(16)
16.6103(18)
90
C21H28Cl2NRh
468.25
monoclinic
P21/c
15.452(2)
8.3872(11)
16.535(2)
90
C21H28I2NRh
651.15
monoclinic
P21/c
16.528(2)
9.0176(11)
15.7935(19)
90
C19H24I2NRh
623.10
monoclinic
P21/c
11.1943(11)
8.3141(8)
21.985(2)
90
529.49
monoclinic
C2/c
22.932(2)
13.9600(15)
14.3440(15)
90
b (Å)
c (Å)
a
(°)
b (°)
125.002(2)
90
3761.4(7)
8
1.870
1.024
R1 = 0.0296
wR2 = 0.0613
R1 = 0.0459
wR2 = 0.0672
124.867(1)
90
3739.5(5)
8
1.564
1.029
R1 = 0.0297
wR2 = 0.0669
R1 = 0.0451
wR2 = 0.0723
115.943(1)
90
2166.6(3)
4
1.601
1.034
R1 = 0.0409
wR2 = 0.0978
R1 = 0.0606
wR2 = 0.1069
91.268(2)
90
2070.8(4)
4
1.788
1.091
R1 = 0.0388
wR2 = 0.0840
R1 = 0.0515
wR2 = 0.0882
109.055(2)
90
2223.9(4)
4
2.211
1.051
R1 = 0.0305
wR2 = 0.0671
R1 = 0.0407
wR2 = 0.0711
101.271(2)
90
2101.6(5)
4
1.480
1.032
R1 = 0.0309
wR2 = 0.0632
R1 = 0.0472
wR2 = 0.0696
108.939(2)
90
2226.5(5)
4
1.943
1.048
R1 = 0.0293
wR2 = 0.0578
R1 = 0.0429
wR2 = 0.0625
97.148(2)
90
2030.2(3)
4
2.039
1.099
R1 = 0.0278
wR2 = 0.0556
R1 = 0.0372
wR2 = 0.00581
c
(°)
V(Å3)
Z
Dcalc (Mg/m3)
Goodness-of-fit, F2
Final R indices
[l > 2r(l)]
R indices
(all data)
2b[P
F6]
1b[P
F6]
1b’[P
F6]
Fig. 3. Intermolecular
p
-stacking displayed in the crystal structures of 1b[PF6], 2b[PF6], and 1b0[PF6]. Thermal ellipsoids are drawn at the 50% probability level. The
asymmetric units displayed are double. Hydrogen atoms were removed for clarity.
distance ranges are in Table 5. A few examples are shown in Fig. 3
and show quite similar structures but are not isostructural.
letting any dimer, 1, 2, or 3, react with sodium acetate first and
then adding the 2,6-xylylisocyanide to the intermediate metal-ace-
tate complex only generated the corresponding isocyanide com-
plex. Using potassium carbonate shown loss of the isocyanide
and complete decomposition of 2a. Stronger nucleophilic bases
such as sodium phenolate and potassium t-butoxide decomposed
2a quickly.
2.4. Halogen abstraction tandem cyclometallation via electrophilic C–
H activation attempts
2.4.1. Reactions with bases
The C–H activation of phenyl imines and phenyl pyridines un-
der mild conditions using 1 or 2 with sodium acetate was previ-
ously shown by our group [26,27]. Applying the same conditions
to either 1a or 2a shown no C–H activation of the benzylic sp3
hydrogens though the chloride had been displaced by acetate. Also
2.4.2. Reactions with silver salts
Attempts with sodium acetate seemed inconclusive and the
extension to silver acetate was made to completely remove the
halogen since with sodium acetate and a dimer like 2 could be in

136
A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
equilibrium with Cp⁄MCl(OAc) and Cp⁄M(OAc)2. The formation of
silver chloride would drive to equilibrium to favor the Cp⁄M(OAc)2
[27] While adding silver acetate, either stoichiometricly or in ex-
cess, did remove the halogen no C–H activation was observed
and isolation of an intermediate metal–isocyano–acetate complex
was not accomplished. Other silver salts such as silver triflate
and silver hexafluorophosphate were used to generate those inter-
mediates as seen above. In regards to C–H activation neither the
4.2. Synthesis of Cp⁄IrCl2(CN-2,6-Xyl), 1a
2,6-Xylyl isocyanide (83 mg, 0.633 mmol) is added to a solution
of [Cp⁄IrCl2]2 (26.2 mg, 0.330 mmol) in THF. The reaction is sealed
and allowed to stir for 1 h. Then the solvent is evaporated, pentane
is added, the mixture is sonicated and then filtered through a frit to
remove excess isocyanide; crude yield 80%. The crude material was
re-crystallized via vapor diffusion with CH2Cl2/pentane; purified
yield 72%. 1H NMR (400 MHz, CDCl3): d 7.16 (m, 1H), 7.09 (d,
2H), 2.45 (s, 6H), 1.86 (s, 15H) 13C{1H} NMR (125 MHz, CDCl3): d
ꢂ
PF6 nor the OTfꢂ anions were helpful and no cationic complexes
with triflate as the counterion were ever isolated. Heating either
1a or 2a with silver acetate or silver trifluoroacetate also did not
promote the formation of an indole species and none were de-
tected via 1H NMR spectroscopy. Heating 1a or 3a with silver tri-
flate also proved futile for generating coordinatively unsaturated
species.
135.5, 132.4, 129.1, 127.9, 127.3, 18.9, 9.2. IR (solid) 2154 cmꢂ1
Anal. Calc. for C19H24Cl2IrN: C, 43.09; H, 4.56; N, 2.64. Found: C,
43.07; H, 4.49; N, 2.71%.
.
4.3. Synthesis of Cp⁄RhCl2(CN-2,6-Xyl), 2a
The synthesis is analogous to 1a; crude yield 98%. Anal. Calc. for
19H24Cl2NRh: C, 51.83; H, 5.49; N, 3.18. Found: C, 51.76; H, 5.41;
N, 3.14%.
2.4.3. Thermolysis and protonolysis
C
The chloro analogues of the 2,6-xylylisocyanide complexes
were heated in benzene but no indole intermediates were de-
tected. The ruthenium lost p-cymene and no reaction was observed
for the group 9 complexes. Heating 2a in trifluoroacetic acid-d1
only caused the isocyanide to dissociate.
4.4. Synthesis of Cp⁄IrI2(CN-2,6-Xyl), 1b
The synthesis is analogous to 1b0; crude yield 84%. Anal. Calc. for
C19H24I2IrN: C, 32.03; H, 3.39; N, 1.96. Found: C, 31.60; H, 3.27; N,
1.93%.
3. Conclusions
4.5. Synthesis of Cp⁄RhI2(CN-2,6-Xyl), 2b
Several new ruthenium, rhodium, and iridium complexes were
synthesized and structurally characterized and analyzed. Halide
abstraction with bulky silver salts allowed for the isolation of sev-
eral ‘chiral-at-metal’ cationic iridium and rhodium complexes.
However further reaction of these complexes to achieve C–H acti-
vation was not observed at the benzylic carbon of the isocyanide,
as supported by crystal structure determination of the cationic sol-
vent adducts.
The synthesis is analogous to 1b0; crude yield 99%. Anal. Calc. for
C19H24I2NRh: C, 36.62; H, 3.88; N, 2.24. Found: C, 36.34; H, 3.75; N,
2.22%.
0
4.6. Synthesis of [(p-cymene)RuI2]2, 30
[(p-cymene)RuCl2]2 (171 mg, 0.279 mmol) and NaI (210 mg,
1.40 mmol) are added to a round bottom flask with a stir bar fol-
lowed by 20 mL THF. A reflux condenser is attached and the flask
is submerged in an oil bath and refluxed for 2 h. Then the mixture
is allowed to cool to room temperature and the solvent is evapo-
rated. The residue is extracted with CH2Cl2, sonicated, and filtered
through Celite with CH2Cl2. The process is repeated 3 times to re-
move any sodium halide. The solvent is evaporated from the com-
bined extracts; crude yield 99%. Anal. Calc. for C20H28I4Ru2: C,
24.55; H, 2.88. Found: C, 24.54; H, 2.71%.
4. Experimental
4.1. General procedures, materials and instrumentation
THF, CH2Cl2, and diethyl ether were purified by passage through
activated alumina columns in a Innovative Technology, Inc. PS-
MD-6 solvent purification system. Once reactions were completed,
however, subsequent workups were done without precaution, as
the neutral compounds are bench stable. Acetonitrile was purified
through activated alumina and Q5 columns from Glass Contour Co.
Pentane, CeliteÒ, and sodium iodide (Fischer Scientific) were used
as received. Manipulations for synthesis of the cationic complexes
were performed under nitrogen in a M. Braun glove box with oxy-
gen and water levels below 1 ppm. Glassware used in the glove box
was dried at 150 °C overnight. Silver hexafluorophosphate was
purchased from Strem Chemicals Inc. and used under nitrogen.
Deuterated solvents were purchased from Cambridge Isotope Lab-
oratories. Chloroform-d1 (d 7.26) was used as received and acetoni-
trile-d3 (d 1.94) was dried over CaH2 and distilled under vacuum.
2,6-Xylyl isocyanide was either purchased from Strem Chemicals
Inc. or synthesized by a modified published procedure [52]. 2,6-
Diethylphenyl isocyanide was synthesized by previously reported
procedure [53]. 1H NMR spectra were recorded using a Avance
400 MHz spectrometer and 13C{1H} NMR spectra were recorded
using an Avance 500 MHz spectrometer. Elemental analyses were
obtained from theCENTC Elemental Analysis Facility at the Univer-
sity of Rochester. IR spectra were recorded using a Shimadzu IR
Prestige-21 FTIR spectrophotometer with a PIKE Technologies MIR-
acle™ single reflection ATR. X-ray diffraction data were collected
using a Bruker SMART APEX II CCD Platform diffractometer.
4.7. Synthesis of (p-cymene)RuCl2(CN-2,6-Xyl)ꢄ½CH2Cl2, 3a
2,6-Xylyl isocyanide (25.7 mg, 0.196 mmol) is added to a solu-
tion of [(p-cymene)RuCl2]2 (60.8 mg, 0.0982 mmol) in dry CH2Cl2.
The reaction is sealed and allowed to stir 2 h. The solvent is evap-
orated, pentane is added, the mixture is sonicated and then filtered
through a frit and the process is repeated 3 times to remove excess
isocyanide; crude yield 98%. The crude material was re-crystallized
via vapor diffusion with CH2Cl2/pentane; purified yield 86%. 1H
NMR (400 MHz, CDCl3): d 7.15 (q, 1H), 7.07 (d, 2H), 5.69 (d, 2H),
5.52 (d, 2H), 5.28 (s, 1H), 2.91 (sept, 1H), 2.45 (s, 6H), 2.33 (s,
3H), 1.31 (d, 6H). 13C{1H} NMR (125 MHz, CDCl3): d 151.8, 135.7,
129.3, 128.0, 127.3, 108.4, 107.9, 88.9, 88.3, 53.6, 31.5, 22.7, 19.2,
19.1. IR (solid): 2164 cmꢂ1. Anal. Calc. for C39H48Cl6N2Ru2: C,
48.81; H, 5.04; N, 2.91. Found: C, 48.81; H, 5.04; N, 2.90%.
4.8. Synthesis of (p-cymene)RuI2(CN-2,6-Xyl), 3b
2,6-Xylyl isocyanide (16.7 mg, 0.127 mmol) is added to a solu-
tion of 3 (61.4 mg, 0.0627 mmol) in dry CH2Cl2. The reaction is
sealed and allowed to stir overnight. The solvent is evaporated,

A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
137
pentane is added, then the mixture is sonicated and then filtered
4.13. Synthesis of (p-cymene)RuCl2(CN-2,6-Et2C6H3), 3a’
through a frit. The process is repeated 3 times to remove any so-
dium halide; crude yield 99%. The crude material was re-crystal-
lized via vapor diffusion with CH2Cl2/pentane; purified yield 86%.
1H NMR (400 MHz, CDCl3): d 7.11 (q, 1H), 7.06 (d, 2H), 5.74 (d,
2H), 5.60 (d, 2H), 3.06 (sept, 1H), 2.61 (s, 3H), 2.51 (s, 6H), 1.32
(d, 6H). 13C{1H} NMR (125 MHz, CDCl3): d 149.1, 135.9, 128.8,
128.0, 111.6, 107.1, 89.8, 89.0, 32.3, 23.1, 20.9, 19.5. IR (solid):
2144 cmꢂ1. Anal. Calc. for C19H23I2NRu: C, 36.79; H, 3.73; N, 2.25.
Found: C, 36.73; H, 3.50; N, 2.18%.
The synthesis is analogous to 3a; crude yield 99%, purified yield
90%. 1H NMR (400 MHz, CDCl3): d 7.25 (m, 1H), 7.11 (d, 2H), 5.69
(d, 2H), 5.52 (d, 2H), 2.93 (septet, 1H), 2.84 (q, 4H), 2.33 (s, 3H),
1.32 (d, 6H), 1.27 (t, 6H). 13C{1H} NMR (125 MHz, CDCl3): d
141.5, 129.6, 108.4, 107.2, 88.7, 88.3, 31.4, 25.6, 22.5, 19.0, 14.2.
IR (solid): 2154 cmꢂ1. Anal. Calc. for C21H27Cl2NRu: C, 54.19; H,
5.84; N, 3.00. Found: C, 53.98; H, 5.77; N, 3.23%.
4.14. Synthesis of (p-cymene)RuI2(CN-2,6-Et2C6H3), 3b0
⁄
0
4.9. Synthesis of Cp IrCl2(CN-2,6-Et2C6H3) ꢄCH2Cl2, 1a0
The synthesis is analogous to 3b; Crude yield 93%. Purified Yield
88%. 1H NMR (400 MHz, CDCl3): d 7.2 (q, 1H), 7.1 (d, 2H), 5.74 (d,
2H), 5.6 (d, 2H), 3.08 (sept, 1H), 2.88 (q, 4H), 2.6 (s, 3H), 1.32 (d,
6H), 1.27 (t, 6H). 13C{1H} NMR (125 MHz, CDCl3): d 141.8, 129.3,
126.4, 111.7, 106.8, 89.7, 89.1, 32.3, 25.9, 23.1, 20.9, 14.9. IR (solid):
2141 cmꢂ1. Anal. Calc. for C21H27I2NRu: C, 38.90; H, 4.19; N, 2.16.
Found: C, 38.23; H, 4.09; N, 2.09%.
[Cp⁄IrCl2]2 (87.7 mg, 0.110 mmol) is added to a round bottom
flask with a stir bar followed by 10 mL of THF. 2,6-Diethylphenylis-
ocyanide (40.3 lL, 0.221 mmol) is added drop-wise while stirring.
The flask is sealed and let stir for 1 h at room temperature. Then
the solvent is evaporated and pentane is added and the mixture
is sonicated and filtered. The process is repeated 3 time to remove
any excess isocyanide; Crude yield 89%. The crude material was re-
crystallized via vapor diffusion with CH2Cl2/pentane; purified yield
47%. 1H NMR (400 MHz, CDCl3):d 7.24 (m, 1H), 7.11 (d, 2H), 5.28 (s,
2H) 2.82 (q, 4H), 1.85 (s, 15H), 1.26 (t, 6H). 13C{1H} NMR (125 MHz,
CDCl3): d 141.6, 129.6, 126.4, 94.4, 86.3, 25.8, 14.2, 9.5, 9.3. IR (so-
lid): 2158 cmꢂ1. Anal. Calc. for C22H30Cl4IrN: C, 41.12; H, 4.70; N,
2.18. Found: C, 41.81; H, 4.67; N, 1.88%.
4.15. Synthesis of [Cp⁄IrCl(MeCN)(CN-2,6-Xyl)]PF6, 1a[PF6]
52.9 mg (0.0999 mmol) of 1 is added to a scintillation vial fol-
lowed by a stir bar, and 10 mL of acetonitrile which is stirred vig-
orously. In a separate vial 25.5 mg (0.101 mmol) of AgPF6 is
dissolved in 2 mL of acetonitrile then added the solution drop-wise
in 4 0.5 mL portions to the stirring mixture. The color immediately
begins to lighten from goldenrod to lemon yellow and the reaction
is stirred for 1 h. The stirring is stopped and the AgCl precipitate
was allowed to settle before decanting and filtering through Celite
with acetonitrile. The solution is concentrated, then precipitated
with ether. The mixture is filtered on a frit and dried under vac-
uum; crude yield 88%. 1H NMR (400 MHz, CD3CN): d 7.34 (q, 1H),
7.27 (d, 2H), 2.45 (s, 6H), 1.96 (s, 3H), 1.88 (s, 15H). 13C{1H} NMR
(125 MHz, CD3CN): d 136.9, 131.2, 129.1, 97.8, 18.8, 9.4. IR (solid):
2327 cmꢂ1 (M–N„C-R), 2185 cmꢂ1 (M-C„N-Ar). Anal. Calc. for
4.10. Synthesis of Cp⁄IrI2(CN-2,6-Et2C6H3), 1b0
74.4 mg (0.133 mmol) of 1a0 and 201 mg (1.34 mmol) of NaI are
added to a round bottom flask with a stir bar followed by 10 ml of
THF. A reflux condenser is attached and the flask is submerged in
an oil bath and refluxed for 3 h. Then the mixture is allowed to cool
to room temperature and solvent is evaporated. The residue is ex-
tracted with CH2Cl2, sonicated, and filtered through Celite with
CH2Cl2. The process was repeated 3 times to remove and sodium
halide. The solvent is evaporated from the combined extracts;
crude yield 95%. The crude material was re-crystallized via vapor
diffusion with CH2Cl2/pentane; purified yield 98%. 1H NMR
(400 MHz, CDCl3): d 7.18 (m, 1H), 7.12 (d, 2H), 2.87 (q, 4H), 2.14
(s, 15H), 1.27 (t, 6H). 13C{1H} NMR (125 MHz, CDCl3): d 141.7,
129.1, 126.3, 95.3, 88.8, 25.7, 14.6, 10.7. IR (solid): 2150 cmꢂ1. Anal.
Calc. for C21H28Cl4IrN: C, 34.06; H, 3.81; N, 1.89. Found: C, 34.54; H,
3.80; N, 1.86%.
C21H27ClF6IrN2P: C, 37.08; H, 4.00; N, 4.11. Found: C, 37.17; H,
3.86; N, 4.17%.
4.16. Synthesis of [Cp⁄IrI(MeCN)(CN-2,6-Xyl)]PF6, 1b[PF6]
The synthesis is analogous to 1a[PF6]; crude yield 87%. 1H NMR
(400 MHz, CD3CN): d 7.32 (q, 1H), 7.26 (d, 2H), 2.48 (s, 6H), 2.04 (s,
15H), 1.96 (s, 3H). 13C{1H} NMR (125 MHz, CD3CN): d 137.1, 131.1,
129.1, 98.5, 19.1, 10.3. IR (solid): 2324 cmꢂ1 (M–N„C-R),
2176 cmꢂ1 (M-C„N-Ar). Anal. Calc. for C21H27F6IIrN2P: C, 32.69;
H, 3.52; N, 3.63. Found: C, 32.84; H, 3.35; N, 3.64%.
4.11. Synthesis of Cp⁄RhCl2(CN-2,6-Et2C6H3), 2a0
4.17. Synthesis of [Cp⁄IrCl(MeCN)(CN-2,6-EtC6H4)]PF6, 1a0[PF6]
The synthesis is analogous to 2a; crude yield 95%, purified yield
89%. 1H NMR (400 MHz, CDCl3):d 7.28 (t, 1H), 7.12 (d, 2H), 2.84 (q,
4H), 1.84 (s, 15H), 1.27 (t, 6H). 13C{1H} NMR (125 MHz, CDCl3):d
The synthesis is analogous to 1a[PF6]; Yield 93%. 1H NMR
(400 MHz, CD3CN): d 7.42 (t, 1H), 7.29 (d, 2H), 2.82 (q, 4H), 1.96
(s, 3H), 1.89 (s, 15H), 1.26 (t, 6H). 13C{1H} NMR (125 MHz, CD3CN):
d 142.8, 131.7, 127.8, 97.8, 26.3, 14.4, 9.4. IR (solid): 2332 cmꢂ1
(M–N„C-R), 2183 cmꢂ1 (M-C„N-Ar). Anal. Calc. for C23H31ClF6-
IrN2P: C, 39.01; H, 4.41; N, 3.95. Found: C, 39.07; H, 4.27; N, 3.87%.
141.6, 130.0, 126.4, 125.4, 25.7, 14.1, 9.6. IR (solid): 2173 cmꢂ1
.
Anal. Calc. for C21H28Cl2NRh: C, 53.86; H, 5.95; N, 2.98. Found: C,
53.75; H, 5.95; N, 2.98%.
4.12. Synthesis of Cp⁄RhI2(CN-2,6-Et2C6H3), 2b0
4.18. Synthesis of [Cp⁄IrI(MeCN)(CN-2,6-EtC6H4)]PF6, 1b0[PF6]
The synthesis is analogous to 2b; crude yield 99%, purified yield
92%. 1H NMR (400 MHz, CDCl3): d 7.23 (t, 1H), 7.1 (d, 2H), 2.86 (q,
4H), 2.16 (s, 15H), 1.27 (t, 6H). 13C{1H} NMR (125 MHz, CDCl3): d
The synthesis is analogous to 1a[PF6]; Yield 87%. 1H NMR
(400 MHz, CD3CN): d 7.39 (t, 1H), 7.28 (d, 2H), 2.85 (q, 4H), 2.04
(s, 15H), 1.96 (s, 3H), 1.26 (t, 6H). 13C{1H} NMR (125 MHz, CD3CN):
d 142.9, 131.6, 127.8, 98.5, 26.3, 14.7, 10.3. IR (solid): 2331 cmꢂ1
(M–N„C-R), 2175 cmꢂ1 (M-C„N-Ar). Anal. Calc. for C23H31F6IIrN2-
P: C, 34.54; H, 3.90; N, 3.50. Found: C, 35.20; H, 3.96; N, 3.48%.
141.8, 129.6, 126.4, 125.8, 25.8, 14.7, 11.3. IR (solid): 2163 cmꢂ1
.
Anal. Calc. for C21H28I2NRh: C, 38.73; H, 4.33; N, 2.15. Found: C,
38.57; H, 4.30; N, 2.08%.

138
A.P. Walsh et al. / Inorganica Chimica Acta 407 (2013) 131–138
4.19. Synthesis of [Cp⁄RhI(MeCN)(CN-2,6-Xyl)]PF6, 2b[PF6]
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The synthesis is analogous 1a[PF6]; Yield 85%. 1H NMR
(400 MHz, CD3CN): d 7.34 (q, 1H), 7.25 (d, 2H), 2.48 (s, 6H), 2.02
(s, 15H), 1.96 (s, 3H). 13C{1H} NMR (125 MHz, CD3CN): d 137.1,
131.4, 129.2, 104.4, 19.1, 10.9. IR (solid): 2326 cmꢂ1 (M–N„C-R),
2182 cmꢂ1 (M–C„N–Ar). Anal. Calc. for C21H27F6IN2PRh: C, 36.97;
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4.20. Synthesis of [Cp⁄RhCl(MeCN)]2[PF6]2, 4
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The synthesis is analogous to 1a[PF6]; yield 97%. 1H NMR
(400 MHz, CD3CN): d 1.96 (s, 6H), 1.67 (s, 30H). 13C{1H} NMR
(125 MHz, CD3CN): d 97.94, 8.5. IR (solid): 2232 cmꢂ1, 2294 cmꢂ1
(M–N„C-R). Anal. Calc.. for C24H36Cl2F12N2P2Rh2: C, 31.36; H,
3.95; N, 3.05. Found: C, 31.59; H, 3.82; N, 2.92%.
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4.21. Synthesis of [Cp⁄Rh(MeCN)3,PF6]2, 5
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The synthesis is analogous to the reported procedure [49]. crude
yield P 99%. Purified yield 84%. Anal. Calc. for C16H24F12N3P2Rh: C,
29.51; H, 3.71; N, 6.45. Found: C, 29.56; H, 3.53; N, 6.38%.
Acknowledgement
[36] M. Paneque, K. Mereiter, L.L. Santos, Organometallics 32 (2013) 565.
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9034.
This work was supported by the National Science Foundation,
grant CHE-1012405.
Appendix A. Supplementary material
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CCDC 939777–939796 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
http://www.ccdc.cam.ac.uk/data_request/cif. Supplementary data
associated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.ica.2013.07.039.
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SI, is unique and crystallized without solvent.
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compound has been synthesized and reported there has been no reported
crystal structure and has been submitted with this report in the SI;
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a = 14.998(2) Å,
b = 90.660(3)°,
b = 33.347(5) Å,
= 90.366(3)°.
c = 33.711(6) Å;
a = 119.481(3)°,
c
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