Reactions of Ruthenium N-Heterocyclic Carbene Complexes
A R T I C L E S
2
1
08.2 (t, JCP ) 9.2 Hz, RusCO), 195.8 (t, JCP ) 8.3 Hz, RusCIiPr2Me2),
42.6 (vt, |JCP + JCP| ) 19.3 Hz, PPh ), 135.1 (vt, |JCP + JCP| ) 6.4
), 129.2 (s, PPh ),
), 128.3 (vt, |JCP + JCP| ) 4.6 Hz, PPh
26.2 (s, im C), 125.9 (s, im C), 54.5 (s, CH), 54.3 (s, CH), 22.6 (s,
temperature. Et
2
O (5 mL) was added to each tube to quench the reaction,
3
and the mixture was concentrated in vacuo to afford the crude product.
Conversions were determined by analysis of the H NMR spectra and
represent the averages of at least two runs.
1
Hz, PPh
1
CH
3
3
3
-
1
3
), 21.4 (s, CH
3
), 11.5 (s, CH
(CO)H (9). Toluene (30 mL) was added to
(0.8 g, 4.4 mmol) and Ru(PPh (CO)H (1.0 g, 1.1 mmol) in
3
). IR (cm ): 1917 (νCO).
X-ray Crystallography. Single crystals of compounds 6, 7, 9, and
11 were analyzed using a Nonius Kappa CCD diffractometer and Mo-
(KR) radiation (λ ) 0.71073 Å), and data for 11 were collected at
Daresbury station 16.2 SMX (λ ) 0.8460 Å). Details of the data
collections, solutions, and refinements are provided in the Supporting
Information. The structures were universally solved using SHELXS-
i
Ru(I Pr
2
Me
2
)′(PPh
3
)
2
IiPr
)
3 3
2
Me
2
2
an ampule under argon. The mixture was stirred at 70 °C for 20 h. The
volatiles were removed in vacuo, and EtOH (20 mL) was added. The
resulting red solution was stirred overnight to afford an off-white
precipitate. The mixture was filtered, and the solid was washed with
hexane (2 × 10 mL) to yield the CsH-activated product 9 as a white
44
44
97 and refined using full-matrix least-squares in SHELXL-97.
Multiscan absorption corrections were applied throughout, and con-
vergence was uneventful, with the following exceptions and points of
note:
solid. Yield: 0.6 g (66%). Anal. Found (calcd) for C48
H
50
N
D
6 6
2
OP
, 400
), 7.02-
), 5.50 (sept, JHH ) 7.1 Hz, 1H, CH), 4.28 (m, 1H,
CH), 1.99 (m, 1H, CH), 1.76 (s, 3H, CH ), 1.66 (s, 3H, CH ), 1.37 (d,
HH ) 7.1 Hz, 3H, CH ), 1.28 (d, JHH ) 6.0 Hz, 3H, CH ), 0.54 (d, JHH
7.1 Hz, 3H, CH
2
Ru:
1
C, 68.57 (69.13); H, 6.40 (6.04); N, 3.25 (3.15). H NMR (C
MHz): δ 7.70-7.66 (m, 6H, PPh ), 7.37-7.32 (m, 6H, PPh
.96 (m, 18H, PPh
The hydride hydrogen in 6 was located and refined at distance of
1.6 Å from the central metal. Disorder vexed the structure of 7, which
was also subject to racemic twinning. In particular, 70:30 disorder was
evident for the positions of the central ruthenium, the carbonyl group,
and the carbene-fragment atoms. Refinement was anisotropic with the
exception of the minor carbene moiety. The minor carbonyl moiety
(C1A and O1A) was refined subject to restraints on the ADPs therein,
and the N1AsC3A and C3AsC4A distances were fixed in the final
least-squares analysis. The hydride trans to the carbene in this structure
was readily located and refined subject to being equidistant from Ru1
and Ru1A. The second hydride ligand could not be reliably located
because of the disorder and, hence, was omitted from the refinement.
In 9, the hydrogen atoms attached to C6 were located and refined at
a distance of 0.89 Å from the parent carbon. The hydride (H1) was
also located and subsequently treated in a manner similar to that for 6.
Modeling of the solid-state structure of complex 11 necessitated
treatment of C8 as being disordered with C8A in a 55:45 ratio. As for
the other structures in this study, the hydride hydrogen was located
and refined at 1.6 Å from the central metal. The hydrogen atoms
attached to C8 and C10 were also located and subsequently refined at
3
3
6
3
3
3
J
3
3
)
J
3
), 0.49 (m, 1H, CH), -7.72 (dd, JHP ) 104.8 Hz,
HP ) 28.0 Hz, 1H, RusH). 31P{ H} NMR: δ 56.5 (d, JPP ) 16.7 Hz,
1
1
3
1
PPh
3
), 35.8 (d, JPP ) 16.7 Hz, PPh ). C{ H} NMR: δ 207.4 (dd, JCP
3
)
8
1
5.5 Hz, JCP ) 13.8 Hz, RusCO), 187.8 (dd, JCP ) 10.1 Hz, JCP
2.7 Hz, RusCIiPr2Me2), 140.3 (dd, JCP ) 34.9 Hz, JCP ) 1.8 Hz, PPh
40.0 (dd, JCP ) 23.0 Hz, JCP ) 1.8 Hz, PPh ), 135.5 (d, JCP ) 11.0
), 134.8 (d, JCP ) 11.0 Hz, PPh ), 129.4-129.0 (m, PPh ),
28.4-128.1 (m, PPh ), 124.0 (s, im C), 123.2 (s, im C), 59.1-58.8
m, CH), 54.0 (s, CH), 24.5 (t, JCP ) 7.4 Hz, CH ), 23.9 (s, CH ), 22.4
)
3
),
3
Hz, PPh
1
3
3
3
3
(
(
(
2
3
-
1
s, CH
ν
3
3 3 3
), 21.4 (s, CH ), 11.3 (s, CH ), 10.0 (s, CH ). IR (cm ): 1884
CO).
i
Ru(I Pr
2
)′(PPh
3 2
)
(CO)H (11). Trimethylvinylsilane (50 equiv) was
(0.6 mL). The sample was heated
6 6
added to 6 (15 mg) dissolved in C D
3
1
1
at 50 °C for 16 h. P{ H} NMR spectroscopy indicated complete
conversion to the CsH-activated complex. The solvent was removed
in vacuo, affording the title compound 11 as an orange solid in
0
.90 Å from the relevant parent atoms. Atom positions H10A, H10B,
quantitative yield. Anal. Found (calcd) for C46
H
46
N
2
OP
, 400 MHz): δ
), 6.26 (d, JHH
.6 Hz, 1H, im CH), 6.20 (d, JHH ) 1.6 Hz, 1H, im CH), 4.61 (sept,
2
Ru: C, 68.36
1
and H10C were refined subject to being equidistant from each other
and 2.02 Å from C10. Successful convergence for 11 was achieved
only after inclusion of a twin law to account for 20% twinning about
the direct 100 direction.
6 6
(68.56); H, 5.79 (5.75); N, 3.46 (3.48). H NMR (C D
7
1
.91-7.69 (m, 12H, PPh
3
), 7.13-6.87 (m, 18H, PPh
3
)
J
HH ) 6.6 Hz, 1H, CH), 3.29-3.15 (m, 1H, CH), 1.37-1.22 (m, 1H,
CH), 1.01-0.87 (m, 1H, CH), 0.77 (d, JHH ) 6.6 Hz, 3H, CH ), 0.72
), -7.20
t, JHP ) 24.7 Hz, 1H, RusH). P{ H} NMR: δ 61.5 (AB, ∆ν )
The absolute structure parameters for 7 and 9 refined to 0.32(2) and
3
0
.02(2), respectively. Crystallographic data have been deposited with
(d, JHH ) 6.6 Hz, 3H, CH
3
), 0.64 (d, JHH ) 6.6 Hz, 3H, CH
3
3
1
1
the Cambridge Crystallographic Data Centre as supplementary publica-
tions CCDC 616616-616619 for compounds 6, 7, 11, and 9 respec-
tively. Copies of the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K. [fax, (+44)
(
3
1
). 1 C{ H} NMR: δ 207.0 (t, JCP
3
1
82.5 Hz, JPP ) 294.9 Hz, PPh
2.9 Hz, RusCO), 195.8 (t, JCP ) 8.3 Hz, RusCIiPr2Me2), 140.3 (dd,
), 140.0 (JCP ) 22.1 Hz, JCP ) 9.2
), 135.1 (dd, JCP ) 20.2 Hz, JCP ) 2.8 Hz, PPh ), 135.0 (dd,
), 129.2 (d, JCP ) 12.9 Hz, PPh ),
), 118.0 (s, im C), 116.0 (s, im C), 60.9
), 24.1 (t, JCP ) 11.0 Hz, CH ), 24.0
3
)
JCP ) 22.1 Hz, JCP ) 9.2 Hz, PPh
3
1
223 336033; e-mail, deposit@ccdc.cam.ac.uk].
Hz, PPh
3
3
JCP ) 20.2 Hz, JCP ) 2.8 Hz, PPh
3
3
Acknowledgment. M.K.W. and J.M.J.W. thank the EPSRC
1
28.5 (d, JCP ) 12.9 Hz, PPh
3
(SB) and University of Bath for financial support. P.S.P. thanks
(
(
s, CH), 52.0 (s, CH), 25.4 (s, CH
s, CH ), 22.9 (s, CH ).
General Procedure for Transfer Hydrogenation of Alkenes and
3
2
the Swiss National Science Foundation and the ETHZ for
funding. We also thank Johnson Matthey plc for the loan of
hydrated RuCl3.
3
3
i
Alcohols. The chosen alkene or alcohol (0.5 mmol) and PrOH or
acetone (5 equiv) were added to Ru(NHC) (PPh (0.01
mmol) dissolved in C in a resealable NMR tube under argon. The
reaction mixtures were heated at 50 °C in the probe of the NMR
spectrometer, and H spectra were recorded at regular intervals for
)
3-n(CO)H
2
Supporting Information Available: Molecular structures of
4-7 (along with selected bond lengths/angles), crystal data and
structure refinement and X-ray crystallographic files (in CIF
format) for complexes 6, 7, 9, and 11. Synthesis and spectro-
scopic details for I Pr2, I Pr2, and ylides. Tables of full catalytic
data for alcohol oxidation and Wittig reactions. Rate constants
and Arrhenius plot associated with the variable-temperature
proton measurements on 1. This material is available free of
charge via the Internet at http://pubs.acs.org.
n
3
6 6
D
1
1
12 h. Conversion was determined by integration of the H NMR spectra,
n
i
and reported values represent the averages of at least two runs.
General Procedure for Indirect Wittig Reactions. The required
ruthenium complex (5 mol %, 25 µmol) and (triphenylphosphora-
nylidene)acetonitrile (0.55 mmol, 1.1 equiv) were charged into a tube
fitted with a resealable Young’s PTFE tap. The tubes were placed in
a carousel synthesizer (Fisher) and purged with argon. Toluene (1 mL)
and the required alcohol (0.5 mmol) were added via syringe, and the
tubes were sealed under argon. The reaction mixtures were heated
JA065790C
(
44) Sheldrick, G. M. Acta. Cryst. 1990, 467-473, A46. Sheldrick, G. M.
SHELXL-97, a Computer Program for Crystal Structure Refinement;
University of G o¨ ttingen: G o¨ ttingen, Germany, 1997
(70 °C for 2, 3, or 20 h or 80 °C for 24 h) and then cooled to room
J. AM. CHEM. SOC.
9
VOL. 129, NO. 7, 2007 1995