Regioselective electrophilic C-H bond activation in triazolylidene metal complexes containing a N-bound phenyl substituent

Article abstract of DOI:10.1021/om300983m

Transmetalation of a 1,4-diphenyl-substituted 1,2,3-triazolylidene silver complex with an electrophilic metal center, e.g., Ru^II, Ir ^III, or Rh^III, induces spontaneous and chemoselective cyclometalation involving C-H bond activation of the N-bound phenyl group exclusively. Less electrophilic metals such as Ir^I, Rh^I, and Pt^II yield a monodentate triazolylidene complex, while cyclometalation with borderline cases (Pd^II) or the activation of the C-bound phenyl ring requires acetate as a promoter.

Full text of DOI:10.1021/om300983m

Article
pubs.acs.org/Organometallics
Regioselective Electrophilic C−H Bond Activation in Triazolylidene
Metal Complexes Containing a N‑Bound Phenyl Substituent
Kate F. Donnelly, Ralte Lalrempuia, Helge Muller-Bunz, and Martin Albrecht*
̈
School of Chemistry & Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
S
* Supporting Information
ABSTRACT: Transmetalation of a 1,4-diphenyl-substituted 1,2,3-
triazolylidene silver complex with an electrophilic metal center, e.g.,
RuII, IrIII, or RhIII, induces spontaneous and chemoselective
cyclometalation involving C−H bond activation of the N-bound
phenyl group exclusively. Less electrophilic metals such as IrI, RhI,
and PtII yield a monodentate triazolylidene complex, while
cyclometalation with borderline cases (PdII) or the activation of
the C-bound phenyl ring requires acetate as a promoter.
yclometalation has become a useful concept for stabilizing
respectively,9a comprising a monodentate triazolylidene (trz)
C
reactive M−C bonds through chelation,1 thus enabling
complex (Scheme 1). Expansion of this methodology to
different metal centers yielded complexes 4−7. Platinum
complex 4 is a cationic version of complex 2 and features a
monodentate triazolylidene ligand and a cod spectator ligand.
Exchange of the noncoordinating anion during the synthesis of
4 from chloride to PF6− enhanced the solubility of the complex
and thus facilitated analysis and reactivity studies. In contrast to
the clean triazolylidene transfer observed with platinum(II),
transmetalation with [RuCl2(cym)]2 as ruthenium(II) pre-
cursor induced spontaneous C−H bond activation of one of the
phenyl substituents and afforded the cyclometalated complex 5
with a Ctrz,CPhe-bidentate bonding mode of the triazolylidene
ligand.12 An identical reaction outcome was observed when
using [IrCl2(Cp*)]2 or [RhCl2(Cp*)]2 as metal precursor for
the generation of the metallacyclic complexes 6 and 7.
exploitation of organometallic entities for materials science and
catalysis.2 Moreover, cyclometalation provides a versatile route
for the directed activation of relatively inert C−H and C−R
bonds, which has spurred the development of mild procedures
for the functionalization of aromatic and aliphatic hydrocarbon
units.3 Typically, cyclometalation is a two-step process that
involves initial binding of a directing group to the metal center
and subsequent metal-mediated C−H bond activation and C−
M bond formation to close the metallacycle.1,4 Classical
directing groups include heteroatom donors, which bind the
metal reversibly. Carbon donors have recently gained relevance,
a development that has been promoted in particular by the
discovery of N-heterocyclic carbenes (NHCs) as powerful
ligands for transition metals.5 For example, Arduengo-type
carbenes that contain an aryl wingtip group as N substituent
form metallacycles through C−H bond activation when bound
to a late transition metal such as ruthenium, palladium, or
platinum,6 and this process also accounts for the deactivation of
derivatives of Grubbs’ second-generation olefin metathesis
catalysts.7
Cyclometalation occurred chemoselectively and involved the
N-substituted phenyl group exclusively. Highly selective CPh−H
bond activation was indicated by the clean NMR spectrum that
revealed only a single isomer. Specifically, the presence of four
distinct signals for the aromatic protons in the low-field region
1
of the H NMR spectrum demonstrates desymmetrization of
Cyclometalation via wingtip C−H bond activation has been
incidentally observed with other carbenes. For example,
triazolylidene ligandsan easily accessible and emerging
subclass of NHCs8have been shown to undergo cyclo-
metalation when bound to palladium(II)9 or iridium(III).10 In
preliminary investigations, we and others noted that the
acetate-induced cyclopalladation of triazolylidenes involved
the N-bound phenyl group specifically.9 Stimulated by these
initial observations, we have investigated the cyclometalation
reaction in more detail. Here we report on the extension of the
cyclometalation to various other platinum-group metals and on
the basic trends that govern the C−H bond activation process
in phenyl wingtip groups.11
the N-bound phenyl group. In addition, two low-field 13C
NMR resonances were observed: e.g. at δC 173.0 (Ctrz) and
166.3 (CPh) for the ruthenium metallacycle 5. A nuclear
Overhauser effect (NOE) between the methyl group bound to
N3 (δH 4.10 ppm) and the doublet at δH 7.91 due to the ortho
protons of the C-bound phenyl ring unambiguously indicated
that this phenyl ring is unaffected and that cyclometalation
occurred at the N-bound phenyl group exclusively.
The monodentate bonding mode in the triazolylidene
1
platinum complex 4 was readily identified in the H NMR
spectrum by the two sets of multiplets for the phenyl ortho
protons at equal integral ratio and a multiplet for the meta and
Previous work established that transmetalation of the
presumably monomeric carbene silver complex 1 with
rhodium(I) or palladium(II) affords complexes 2 and 3,
Received: October 19, 2012
Published: November 29, 2012
© 2012 American Chemical Society
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Scheme 1
Figure 1. ORTEP plots of complexes 2 (a), 4 (b; only one of the two disordered conformations shown), 6 (c), and 5 (d). All ellipsoids are given at
the 50% probability level, and hydrogen atoms are omitted for clarity.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for Complexes 2 and 4−6
2 (M = Rh)
4 (M = Pt) A
4 (M = Pt) B
5 (M = Ru)
6 (M = Ir)
M−Cl
M−Ctrz
M−CCOD
M−CCOD
M−CCOD
M−CCOD
2.3841(4)
2.3026(19)
1.991(10)
2.155(7)
2.172(8)
2.232(9)
2.266(9)
2.3026(19)
2.031(11)
2.155(7)
2.172(8)
2.232(9)
2.266(9)
2.4208(3)
2.4935(5)
2.013(2)
2.0390(16)
2.1051(16)
2.1178(16)
2.1839(17)
2.1971(17)
2.0372(15)
M−CPh
2.0831(15)
77.79(6)
2.055(2)
Ctrz−M−CPh
Ctrz−M−Cl
CPh−M−Cl
N1−Ctrz−M
Ctrz−Ctrz−M
Cl−M−Ctrz−N1
Cl−M−Ctrz−Ctrz
78.32(10)
87.81(7)
88.16(4)
88.31(4)
88.26(7)
132.26(12)
125.87(12)
−75.16(14)
99.54(13)
127.2(11)
127.7(10)
−67(2)
130.8(10)
124.8(11)
110(3)
115.57(11)
142.69(11)
1.64(11)
115.71(18)
141.98(19)
−2.42(18)
175.2(3)
102(3)
−73(3)
178.91(19)
para protons. On the basis of NOE experiments, the high-field
doublet at δH 8.17 was assigned to the C-bound phenyl ring
and the more shielded set at 7.95 ppm was accordingly
attributed to the phenyl group bound to the heterocyclic
nitrogen. The olefinic protons of the cod ligand are split into a
low-field multiplet (2H) and two multiplets at higher field (1H
each). The high-field signals display well-resolved coupling to
195Pt with a coupling constant (JPtH = 62 Hz) similar to that in
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[PtCl2(cod)] (JPtH = 66.4 Hz), thus suggesting a trans-
positioned chloride ligand. In contrast, the Pt−H coupling is
only poorly resolved in the low-field resonance, and from the
broadening of the socket of the signal, a coupling constant
smaller than 40 Hz may be inferred. This small coupling
constant is in agreement with the high trans influence
attributed to these mesoionic triazolylidene ligands. As
expected for a planar chiral system, a desymmetrization of
the phenyl nuclei was observed in the 13C NMR spectrum (cf.
multiplets for the ortho phenyl protons in 1H NMR
spectroscopy). The platinum-bound carbon resonates at 144.2
ppm (1JPtC not resolved).
was treated with HCl in methanol (room temperature, 24 h).
Likewise, no deuterium incorporation was detected upon
reaction of complexes 5−7 in DCl/iPrOD-d8 at reflux for a
short period of time (10 min). Upon prolonged heating, slow
decomposition was noted as the only reactivity pattern. In
contrast, chelation in the palladacycle 8 is unstable under acidic
conditions and the compound reverts to the monodentate
species 3.
Even though cyclometalation with the diphenyl-substituted
triazolylidene precursor is chemoselective and exclusively
involves C−H activation of the N-bound phenyl ring, activation
of the C-bound phenyl group would be possible, in principle.
For example, when using a N,N′′-dimethyl C-phenyl
substituted triazolium precursor, cycloiridation was observed
in the presence of NaOAc (eq 2).10b Of note, the primary
The connectivity patterns deduced from NMR spectroscopic
analyses were unambiguously confirmed by single-crystal X-ray
diffraction analysis of complex 2 as well as the new complexes
4−6. Thus, the molecular structure of complexes 2 and 4
features a square-planar metal center bound to the cod ligand, a
chloride, and the monodentate triazolylidene ligand (Figure
1a,b). In both complexes, the olefinic carbons trans to chloride
are about 0.07 Å closer to the metal center than those bound
trans to the triazolylidene ligand (Table 1). A similar trans
influence was observed with Arduengo-type NHCs.13 In
complexes 5 and 6, the triazolylidene ligand is bidentate
chelating via the N-bound phenyl group (Figure 1c,d). The bite
angle is 78° in both complexes, and the M−CPh bond is about
0.05 Å longer than the M−Ctrz bond.14 The M−Ctrz bond
length is not significantly affected by the bidentate bonding
mode and falls within the 1.99−2.04 Å range for all four
complexes. Nonetheless, chelation has distinct structural
implications. A pronounced yaw distortion15 was noted for
the chelating systems (13.56 and 13.14° for 5 and 6,
respectively), while the corresponding distortion is much
smaller in the monodentate complexes (<3.2° in complexes 2
and 4). In addition, the triazolylidene plane coincides with the
planar metallacycle, as indicated by the negligibly small dihedral
angles. In contrast, the triazolylidene ligand is strongly twisted
out of the coordination square plane of rhodium and platinum
in complexes 2 and 4 (dihedral angles between 67 and 81°).
Attempts to promote cyclometalation included the reaction
of the monodentate complexes 2−4 with OAc− as a privileged
proton scavenger.16 However, the rhodium complex 2 and the
platinum analogue 4 were inert under a variety of different
reaction conditions (coordinating or noncoordinating solvent,
room or elevated temperature), even when using AgOAc as a
combined potential proton and halide scavenger. Reactions
were also carried out in CD3OD to monitor transient
cyclometalation, though no deuterium incorporation into either
of the phenyl substituents was identified. In contrast, the
palladium triazolylidene complex 3 cleanly underwent cyclo-
palladation in the presence of NaOAc at room temperature to
produce complex 8 (eq 1):9a i.e., the palladium analogue of
complexes 5−7.
product of the transmetalation reaction is the monodentate
carbene iridium complex 9, and cyclometalation requires
prolonged heating in C2D4Cl2 in comparison to the smooth
C−H activation of the N-bound phenyl group upon formation
of 5 already at room temperature. In agreement with the
energetically demanding forward reaction, the reverse iridacycle
ring opening in 10 is facile and the presence of HCl rapidly
restores the monodentate bonding mode.
The observed reactivity patterns provide some insights into
key factors that govern cyclometalation in these triazolylidene
metal complexes. Cyclometalation is substantially easier with
electron-rich phenyl rings: i.e., aniline-type arenes that are
bound to the nitrogen of the heterocyclic carbene. In addition,
electron-poor metal centers (high-valent RhIII, IrIII, RuII)
spontaneously induce C−H activation, while electron-rich
centers (RhI, PtII) are resistant to cyclometalation. In addition,
acetate assists cyclometalation in borderline cases (PdII, IrIII if
the C-bound phenyl group is involved). These trends are all
consistent with an electrophilic bond activation mechanism, as
extensively studied both experimentally and theoretically.17
Support for this general pattern was obtained by the
successful cyclometalation of rhodium when starting from
complex 2. Rather than directly forcing a C−H activation, this
complex was stirred in the presence of dichloro(phenyl)iodine-
(III), which induced rhodium oxidation and spontaneous
cyclometalation to give complex 11 (eq 3). Despite the limited
stability of this complex and the formation of detectable
amounts of triazolium salt as side product, unambiguous
evidence for the formation of 11 was obtained from NMR
spectroscopic analysis. The 1H NMR spectrum reveals a
The metallacycles in complexes 5−7 were remarkably robust.
No ring opening was observed when any of these complexes
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the exclusion of light. The mixture was diluted with CH2Cl2 and
filtered through Celite. All volatiles were removed in vacuo to afford
the silver carbene (0.122 g, 0.160 mmol) as a white solid. The silver
carbene was immediately added to a solution of [Ru(p-cymene)Cl2]2
(0.100 g, 0.160 mmol) in dry CH2Cl2 (10 mL), and the solution was
stirred at room temperature for 16 h. The reaction mixture was diluted
with CH2Cl2 and filtered through Celite. All volatiles were removed in
vacuo, and the orange residue was washed with pentane and then
dissolved in CH2Cl2. Pentane was added, and the resulting mixture was
centrifuged. The supernatant and washings were combined, and all
volatiles were evaporated, yielding the complex as a brown-orange
diagnostic desymmetrization of the N-bound phenyl group into
four distinct resonances. Moreover, the phenyl carbon bound to
the rhodium center appeared as a doublet at 149.5 ppm (1JRhC
= 28.9 Hz).
In conclusion, selective aromatic C−H bond activation of the
N-bound phenyl wingtip group in triazolylidenes has been
demonstrated to follow an electrophilic pathway. These results
suggest that the aniline-type character of the phenyl ring, with
the N substituent as an electron donor, is prevailing over the
potentially electron-withdrawing character of the azolium
system. The high propensity of the N-phenyl wingtip group
to undergo cyclometalation is expected to have implications for
catalyst design. Specifically in borderline cases, where cyclo-
metalation is reversible, proton-coupled redox processes may
become accessible.
solid (0.062 g, 31%). 1H NMR (400 MHz, CDCl3): δ 8.22 (d, 3JHH
=
3
8.0 Hz, 1H, H6), 7.91 (d, JHH = 9.6 Hz, 2H, HC‑Ph ortho), 7.61−7.57
(m, 4H, H5 + HC‑Ph meta+para), 7.11 (t, JHH = 8.0 Hz, 1H, H4), 7.01 (t,
3
3JHH = 7.4 Hz, 1H, H3), 5.26−5.23 (m, 2H, Hcym), 4.83−4.79 (m, 2H,
H
cym), 4.10 (s, 3H, N−CH3), 2.13 (sept, 3JHH = 7.2 Hz, 1H, CHMe2),
3
1.93 (s, 3H, cym CH3), 0.81, 0.73 (2 × d, JHH = 7.2 Hz, 3H,
CHCH3). 13C{1H} NMR (100 MHz, CDCl3): δ 173.0 (Ctrz−Ru),
166.3 (CPh−Ru), 145.7 (Ctrz−Ph), 144.9 (CPh−N), 142.0 (C6), 130.7
(CC‑Ph ortho), 129.7, 128.8 (CC‑Ph meta+ para), 128.7 (CC‑Ph ipso), 127.3
(C5), 122.3 (C4), 113.8 (C3), 102.2, 99.7 (2 × Ccym−C), 89.7, 89.5,
88.5, 84.4 (4 × Ccym−H), 37.0 (NCH3), 30.9 (CHMe2), 23.0 21.5 (2
× CHCH3), 18.9 (cym CH3). Anal. Calcd for C25H26ClN3Ru
(505.01): C, 59.46; H, 5.19; N, 8.32. Found: C, 59.11; H, 5.15; N,
8.23.
EXPERIMENTAL SECTION
■
General Considerations. All metalation reactions were carried
out under strict exclusion of air using standard Schlenk techniques. 3-
Methyl-1,4-diphenyl triazolium iodide, the triazolylidene complexes
1−39a and 8−10,10b and the precursor salts [IrCp*Cl2]18 and
[Pt(cod)Cl2]19 were prepared according to literature procedures. All
other reagents were commercially available and used as received. NMR
spectra were recorded at 25 °C, and chemical shifts (δ in ppm and
coupling constants J in Hz) were referenced to the protio signal of
residual solvent and are reported downfield from SiMe4 (1H, 13C). The
19F NMR shifts are referenced by using the absolute 19F NMR
frequency and the field offset (Z0) of the corresponding NMR solvent.
Assignments are based on homo- and heteronuclear correlation
spectroscopy. The adopted atom numbering in the cyclometalated
compounds starts at the metal-bound carbon (C1), circles toward the
nitrogen-bound carbon (C2), and finishes at C6, the carbon ortho to
the metal-bound carbon. Elemental analyses were performed by the
Microanalytical Laboratory at University College Dublin, Ireland.
Complex 4. Dry CH2Cl2 (18 mL) was added to the triazolium salt
(0.108 g, 0.40 mmol) and Ag2O (0.051 g, 0.22 mmol). The reaction
mixture was stirred at room temperature for 5 h under an inert
atmosphere in the dark. The mixture was then diluted with CH2Cl2
and filtered through a pad of Celite. All volatiles were removed in
vacuo to afford the silver carbene complex 1 (0.126 g, 0.168 mmol) as
a white solid. This residue was immediately added to [Pt(cod)Cl2]
(0.126 g, 0.336 mmol) in CH2Cl2, and the solution was stirred at room
temperature for 16 h. The reaction mixture was diluted with CH2Cl2
and filtered through Celite twice and then concentrated to ca. 2 mL.
Acetone (20 mL) was added, followed by addition of KPF6 (0.062 g,
0.328 mmol). A white precipitate immediately formed. The mixture
was stirred at room temperature for 3 h and then filtered through
Celite, with CH2Cl2 (100 mL) and acetone (25 mL) as eluents. The
filtrates were combined, and all volatiles were removed in vacuo,
yielding complex 4 as an off-white solid (0.098 g, 40%). An analytically
pure sample was obtained by slow diffusion of pentane into a solution
Complex 6. Under a nitrogen atmosphere, the triazolium salt (0.55
g, 0.20 mmol) and Ag2O (0.025 g, 0.11 mmol) were suspended in dry
CH2Cl2 (10 mL), and the reaction mixture was stirred at room
temperature for 5 h in the absence of light. The mixture was filtered
through Celite onto [IrCp*Cl2]2 (0.080 g, 0.10 mmol). The resulting
solution was stirred at room temperature for 16 h. The reaction
mixture was subsequently diluted with CH2Cl2 and filtered through
Celite. The filtrate was evaporated to dryness in vacuo, and the residue
was dissolved in CH2Cl2 (3 mL) followed by the addition of pentane
(60 mL). The solution was left at 4 °C for 48 h. During this period, a
yellow-orange precipitate formed, which was separated by filtration
and then redissolved in a minimal quantity of CH2Cl2. The solution
was filtered through a short pad of silica and eluted with CH2Cl (50
mL) and then with acetone/CH2Cl2 (10/1, 50 mL). All volatiles of the
filtrate were removed in vacuo, affording complex 6 as a light orange
solid (0.063 g, 52%). Slow diffusion of pentane into a solution of 6 in
CH2Cl2 yielded an analytically pure sample. 1H NMR (400 MHz,
CDCl3): δ 7.86 (dd, 1H, 3JHH = 7.6 Hz, 4JHH = 0.8 Hz, H6), 7.80 (dd,
2H, 3JHH = 8.0 Hz, 4JHH = 1.6 Hz, HC‑Ph ortho), 7.65 (dd, 3JHH = 7.6 Hz,
4JHH = 1.0 Hz, H3), 7.57−7.51 (m, 3H, HC‑Ph meta+para), 7.13 (td, 1H,
3JHH = 7.6 Hz, 4JHH = 1.0 Hz, H5), 7.02 (td, 1H, 3JHH = 7.6 Hz, 4JHH
=
1.0 Hz, H4), 4.09 (s, 3H, NCH3), 1.49 (s, 15H, Cp−CH3). 13C{1H}
NMR (100 MHz, CDCl3): δ 150.2 (Ctrz−Ir), 144.9 (CPh−N), 144.8
(CPh−Ir), 143.7 (Ctrz−Ph), 137.5 (C6), 130.7 (CC‑Ph ortho), 129.6, 128.9
(CC‑Ph meta+para), 128.2 (CC‑Ph ipso), 121.9 (C4), 113.5 (C3), 90.3 (CCp),
36.9 (N−CH3), 9.1 (Cp−CH3). Anal. Calcd. for C25H27N3IrCl
(716.6)·CHCl3: C, 43.58; H, 3.94; N, 5.86. Found: C, 43.51; H,
3.80; N, 6.14.
Complex 7. The triazolium salt (0.088 g, 0.32 mmol), Ag2O (0.045
g, 0.19 mmol), and [RhCp*Cl2]2 (0.10 g, 0.16 mmol) were placed
under nitrogen. Dry CH2Cl2 (10 mL) was added, and the reaction
mixture was stirred at room temperature for 18 h under the exclusion
of light. The reaction mixture was diluted with CH2Cl2 and filtered
through Celite. The filtrate was evaporated to dryness in vacuo. The
residue was extracted with Et2O (3 × 20 mL), and the combined
organic fractions were evaporated, thus yielding the product as a
1
of 4 in CHCl3. H NMR (400 MHz, CDCl3): δ 8.18−8.16 (m, 2H,
HPh ortho), 7.96−7.93 (m, 2H, HPh ortho), 7.66−7.61 (m, 6H,
3
HPh meta+para), 5.88−5.79 (m, 2H, CHcod), 4.71 (td, JHH = 3.9 Hz,
3JHH = 7.3 Hz, JPtH = 62 Hz, 1H, CHcod), 4.57 (td, 3JHH(alkene) = 3.9 Hz,
3JHH = 7.5 Hz, JPtH = 62 Hz, 1H, CHcod), 4.20 (s, 3H, NCH3), 2.32−
2.12 (m, 6H, CH2 cod), 1.95−1.81 (m, 2H, CH2 cod). 13C{1H} NMR
(100 MHz, CDCl3): δ 144.2 (Ctrz−Pt, 1JPtC not resolved), 138.8 (Ctrz−
Ph), 138.4 (N−CPh), 131.1, 131.0, 130.7, 129.8, 129.4, 126.0, 125.3,
116.0, 115.8 (9 × CPh), 100.2, 95.5, 93.2 (3 × CHcod), 38.1 (N−CH3),
31.9, 31.8, 28.5, 28.3 (4 × CH2 cod). 19F NMR (376 MHz, CDCl3): δ
1
yellow solid (83 mg, 50%). H NMR (400 MHz, CD2Cl2): δ 7.91−
7.86 (m, 3H, H6, HC‑Ph ortho), 7.63 (dd, 3JHH = 8 Hz, 4JHH = 1.2 Hz, 1H,
H3), 7.61−7.53 (m, 3H, HC‑Ph ortho+meta), 7.19 (td, 3JHH = 8 Hz, 4JHH
=
1
1.6 Hz, 1H, H5), 7.10 (td, 3JHH = 8 Hz, 4JHH = 1.2 Hz, 1H, H4), 4.15 (s,
3H, N−CH3), 1.41 (s, 15H, Cp−CH3). 13C{1H} NMR (101 MHz,
CD2Cl2): δ 167.5 (d, 1JRhC = 52.1 Hz, Ctrz−Rh), 161.7 (d, 1JRhC = 35.6
Hz, CPh−Rh), 145.5 (CPh−N), 145.3 (Ctrz−Ph), 138.7 (C6), 130.6
(CC‑Ph ortho), 129.6 (CC‑Ph para), 128.8 (CC‑Ph meta), 128.2 (CC‑Ph ipso),
127.7 (C5), 122.6 (C4), 113.4 (C3), 97.0 (CCp), 37.2 (N−CH3), 9.1
−74.14 (d, JFP = 713 Hz, PF6). Anal. Calcd for C23H25ClF6N3PPt
(718.96)·0.5CH2Cl2: C, 37.07; H, 3.44; N, 5.52; P, 4.07. Found: C,
36.80; H, 3.13; N, 5.29; P, 4.31.
Complex 5. Dry CH2Cl2 (18 mL) was added to the triazolium salt
(0.108 g, 0.40 mmol) and Ag2O (0.051 g, 0.22 mmol). The reaction
mixture was stirred at room temperature for 5 h under nitrogen and
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(Cp−CH3). HRMS (ESI+): m/z 472.1250 [M − Cl]+, calcd for
C25H27N3Rh 472.1260.
(2) (a) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 40,
3750. (b) van der Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103,
1759. (c) Zhao, J.; Goldman, A. S.; Hartwig, J. F. Science 2005, 307,
1080. (d) Williams, J. A. G. Chem. Soc. Rev. 2009, 38, 1783. (e) Huang,
Z.; White, P. S.; Brookhart, M. Nature 2010, 465, 598. (f) Choi, J.; Roy
MacArthur, A. H.; Brookhart, M.; Goldman, A. S. Chem. Rev. 2011,
111, 1761. (g) Choi, J.; Wang, D. Y.; Kundu, S.; Choliy, Y.; Emge, T.
J.; Krogh-Jespersen, K.; Goldman, A. S. Science 2011, 332, 1545.
(h) Albrecht, M.; Lindner, M. M. Dalton Trans. 2011, 40, 8733.
(3) (a) Snieckus, V. Chem. Rev. 1990, 90, 879. (b) Colby, D. A.;
Bergman, R. G.; Ellman, J. A. Chem. Rev. 2010, 110, 624. (c) Lyons, T.
W.; Sanford, M. S. Chem. Rev. 2010, 110, 1147. (d) Ackermann, L.
Chem. Rev. 2011, 111, 1315.
(4) (a) Dunina, V. V.; Gorunova, O. N. Russ. Chem. Rev. 2004, 73,
309. (b) Vicente, J.; Saura-Llamas, I. Comments Inorg. Chem. 2007, 28,
39.
(5) (a) Bourissou, D.; Guerret, O.; Gabbai, F. P.; Bertrand, G. Chem.
Rev. 2000, 100, 39. (b) Herrmann, W. A. Angew. Chem., Int. Ed. 2002,
41, 1290. (c) Hahn, F. E.; Jahnke, M. C. Angew. Chem., Int. Ed. 2008,
47, 3122. (d) Diez-Gonzalez, S.; Marion, N.; Nolan, S. P. Chem. Rev.
2009, 109, 3612. (e) Poyatos, M.; Mata, J. A.; Peris, E. Chem. Rev.
2009, 109, 3677. (f) Melaimi, M.; Soleilhavoup, M.; Bertrand, G.
Angew. Chem., Int. Ed. 2010, 49, 8810.
Complex 11. Dry CH2Cl2 (15 mL) was added to dichloro-
(phenyl)iodine(III) (0.068 g, 0.226 mmol) and 2 (0.052 g, 0.123
mmol) under a N2 atmosphere, and the solution was stirred for 16 h at
room temperature. CH3CN (2 mL) was added, and the reaction
mixture was stirred for a further 2 h. All volatiles were removed in
vacuo, and the residue was washed with Et2O (3 × 10 mL) and CHCl3
(15 mL). The light yellow solid (0.042 g, 70%) was dried under
reduced pressure and stored under nitrogen at 4 °C to minimize
1
3
decomposition. H NMR (400 MHz, CD3CN): δ 7.89 (d, JHH = 8
Hz, 1H, H6), 7.85 (d, 3JHH = 8 Hz, 2H, HC‑Ph ortho), 7.66−7.60 (m, 4H,
H3 + HC‑Ph ortho+meta), 7.20 (t, JHH = 8 Hz, 1H, H5), 7.13 (t, JHH = 8
Hz, 1H, H4), 4.06 (s, 3H, N−CH3). 13C{1H} NMR (101 MHz,
CD3CN) δ 149.5 (d, 2JRhC = 28.9 Hz, CPh−Rh), 144.5 (CPh−N), 144.4
(Ctrz−Ph), 137.4 (C6), 131.3 (CC‑Ph ortho), 130.1 (CC‑Ph para), 128.4
(CC‑Ph meta), 127.3 (C5), 127.1 (CC‑Ph ipso), 123.1 (C4), 113.6 (C3), 37.4
(N−CH3), Ctrz−Rh not resolved. HRMS (ESI+): m/z 454.0297 [M −
Cl]+, calcd for C19H18ClN5Rh 454.0306.
3
3
Crystal Structure Determinations. Crystal data for 2 and 4−6
were collected using an Oxford Diffraction SuperNova A diffrac-
tometer fitted with an Atlas detector. 6 was measured with Cu Kα
radiation (1.54184 Å); all others were measured with Mo Kα radiation
(0.71073 Å). An at least complete data set was collected, assuming that
the Friedel pairs are not equivalent. An analytical absorption
correction based on the shape of the crystal was performed for all
these crystals.20 The structures were solved by direct methods using
SHELXS-9721 and refined by full-matrix least squares on F2 for all data
using SHELXL-97. Their isotropic thermal displacement parameters
were fixed to 1.2 times (1.5 times for methyl groups) the equivalent
parameter of the parent atom. Anisotropic thermal displacement
parameters were used for all non-hydrogen atoms.
Further crystallographic details are compiled in the Supporting
Information. CCDC numbers 905706 (2), 905705 (4), 905704 (5),
and 905703 (6) contain supplementary crystallographic data for this
paper. These data can be obtained free of charge from the Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
(6) (a) Hiraki, K.; Onishi, M.; Sugino, K. J. Organomet. Chem. 1979,
171, C50. (b) Hiraki, K.; Sugino, K. J. Organomet. Chem. 1980, 201,
469. (c) Huang, J.; Stevens, E. D.; Nolan, S. P. Organometallics 2000,
19, 1194. (d) Jazzar, R. F. R.; Macgregor, S. A.; Mahon, M. F.;
Richards, S. P.; Whittlesey, M. K. J. Am. Chem. Soc. 2002, 124, 4944.
(e) Crudden, C. M.; Allen, D. P. Coord. Chem. Rev. 2004, 247, 2247.
(f) Frey, G. D.; Schutz, J.; Herdtweck, E.; Herrmann, W. A.
̈
Organometallics 2005, 24, 4416. (g) Stylianides, N.; Danopoulos, A.
A.; Pugh, D.; Hancock, F.; Zanotti-Gerosa, A. Organometallics 2007,
26, 5627. (h) Liu, Z.; Zhang, T.; Shi, M. Organometallics 2008, 27,
2668. (i) Haller, L. J. L.; Page, M. J.; Macgregor, S. A.; Mahon, M. F.;
̈
Whittlesey, M. K. J. Am. Chem. Soc. 2009, 131, 4604. (j) Petretto, G.
L.; Wang, M.; Zucca, A.; Rourke, J. P. Dalton Trans. 2010, 39, 7822.
(k) Tang, C. Y.; Thompson, A. L.; Aldrige, S. J. Am. Chem. Soc. 2010,
132, 10578.
(7) Trnka, T. M.; Morgan, J. P.; Sanford, M. S.; Wilhelm, T. E.;
Scholl, M.; Choi, T.-L.; Ding, S.; Day, M. W.; Grubbs, R. H. J. Am.
Chem. Soc. 2003, 125, 2546.
(8) (a) Mathew, P.; Neels, A.; Albrecht, M. J. Am. Chem. Soc. 2008,
130, 13534. (b) Guisado-Barrios, G.; Bouffard, J.; Donnadieu, B.;
Bertrand, G. Angew. Chem., Int. Ed. 2010, 49, 4759. (c) Crowley, J. D.;
Lee, A.-L.; Kilpin, K. J. Aust. J. Chem. 2011, 64, 1118.
ASSOCIATED CONTENT
* Supporting Information
Figures giving NMR spectra of 7 and 11 and CIF files giving X-
ray crystal data for 2 and 4−6. This material is available free of
charge via the Internet at http://pubs.acs.org.
■
S
(9) (a) Poulain, A.; Canseco-Gonzalez, D.; Hynes-Roche, R.; Muller-
̈
AUTHOR INFORMATION
Corresponding Author
*Tel: +353-17162504. Fax: +353-17162501. E-mail: martin.
albrecht@ucd.ie.
■
Bunz, H.; Schuster, O.; Stoeckli-Evans, H.; Neels, A.; Albrecht, M.
Organometallics 2011, 30, 1021. (b) Saravanakumar, R.; Ramkumar,
V.; Sankararaman, S. Organometallics 2011, 30, 1689.
(10) (a) Lalrempuia, R.; McDaniel, N. D.; Muller-Bunz, H.;
̈
Bernhard, S.; Albrecht, M. Angew. Chem., Int. Ed. 2010, 49, 9765.
Notes
(b) Petronilho, A.; Rahman, M.; Woods, J. A.; Al-Sayyed, H.; Muller-
̈
The authors declare no competing financial interest.
Bunz, H.; MacElroy, J. M. D.; Bernhard, S.; Albrecht, M. Dalton Trans.
2012, 41, 13074.
ACKNOWLEDGMENTS
(11) Presented in parts at the XXV International Conference on
Organometallic Chemistry, September 2012, Lisbon (abstract F2.23).
(12) The same cycloruthenation has also been reported by: Inomata,
S.; Ogata, K.; Fukuzawa, S. XXV International Conference on
Organometallic Chemistry; Sept 2012, Lisbon, abstract PB.61.
(13) For examples, see: (a) Herrmann, W. A.; Elison, M.; Fischer, J.;
Koecher, C.; Artus, G. R. J. Chem.Eur. J. 1996, 2, 772. (b) Khramov,
D. M.; Lynch, V. M.; Bielawski, C. W. Organometallics 2007, 26, 6042.
(c) Sato, H.; Fujihara, T.; Obora, Y.; Tokunaga, M.; Kiyosu, J..; Tsuji,
Y. Chem. Commun. 2007, 269.
(14) (a) Corberan, R.; Sanau, M.; Peris, E. J. Am. Chem. Soc. 2006,
128, 3974. (b) Corberan, R.; Sanau, M.; Peris, E. Organometallics 2006,
25, 4002.
(15) Leung, C. H.; Incarvito, C. D.; Crabtree, R. H. Organometallics
2006, 25, 6099.
■
We gratefully acknowledge financial support by the Irish
Research Council (fellowship to K.F.D.), Science Foundation
Ireland, and the European Research Council for a starting grant
(ERC-StG 208561), and we thank Johnson Matthey for a
generous loan of precious metals.
REFERENCES
■
(1) (a) Dehand, J.; Pfeffer, M. Coord. Chem. Rev. 1976, 18, 327.
(b) Ryabov, A. D. Chem. Rev. 1990, 90, 403. (c) Canty, A. J.; van
Koten, G. Acc. Chem. Res. 1995, 28, 406. (d) Dupont, J.; Consorti, C.
S.; Spencer, J. Chem. Rev. 2005, 105, 2527. (e) Djukic, J.-P.; Sortais, J.-
B.; Barloy, L.; Pfeffer, M. Eur. J. Inorg. Chem. 2009, 817. (f) Albrecht,
M. Chem. Rev. 2010, 110, 576.
8418
dx.doi.org/10.1021/om300983m | Organometallics 2012, 31, 8414−8419

Organometallics
Article
(16) (a) Davies, D. L.; Donald, S. M. A.; Macgregor, S. A. J. Am.
Chem. Soc. 2005, 127, 13754. (b) Boutadla, Y.; Al-Duaij, O.; Davies, D.
L.; Griffith, G. A.; Singh, K. Organometallics 2009, 28, 433.
(c) Boutadla, Y.; Davies, D. L.; Jones, R. C.; Singh, K. Chem. Eur. J.
2011, 17, 3438.
(17) (a) Davies, D. L.; Al-Duaij, O.; Fawcett, J.; Giardiello, M.;
Hilton, S. T.; Russell, D. R. Dalton Trans. 2003, 4132. (b) Davies, D.
L.; Donald, S. M. A.; Al-Duaij, O.; Fawcett, J.; Little, C.; Macgregor, S.
A. Organometallics 2006, 25, 5976. (c) Davies, D. L.; Donald, S. M. A.;
Al-Duaij, O.; Macgregor, S. A.; Polleth, M. J. Am. Chem. Soc. 2006,
128, 4210. (d) Garcia-Cuadrado, D.; de Mendoza, P.; Braga, A. A. C.;
Maseras, F.; Echavarren, A. M. J. Am. Chem. Soc. 2007, 129, 6880.
(e) Gorelsky, S. I.; Lapointe, D.; Fagnou, K. J. Am. Chem. Soc. 2008,
130, 10848. (f) Stuart, D. R.; Bertrand-Laperle, M.; Burgess, K. M. N.;
Fagnou, K. J. Am. Chem. Soc. 2008, 130, 16474. (g) Boutadla, Y.;
Davies, D. L.; Macgregor, S. A.; Poblador-Bahamonde, A. I. Dalton
Trans. 2009, 5820. (h) Kefalidis, C. E.; Baudoin, O.; Clot, E. Dalton
Trans. 2010, 39, 10528. (i) Balcells, D.; Clot, E.; Eisenstein, O. Chem.
Rev. 2010, 110, 749.
(18) Ball, R. G.; Graham, W. A. G.; McMaster, A. D.; Mattson, B. M.;
Michel, S. T. Inorg. Chem. 1990, 29, 2023.
(19) Baldwin, J. A.; Butler, I. S.; Gilson, D. F. R. Inorg. Chim. Acta
2006, 359, 3079.
(20) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.
(21) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
8419
dx.doi.org/10.1021/om300983m | Organometallics 2012, 31, 8414−8419