Ortho-Metalated Ruthenium Hydrido Dihydrogen Complexes: Dynamics, Exchange Couplings, and Reactivity

Article abstract of DOI:10.1021/om034259c

The synthesis and properties of the neutral hydrido dihydrogen ortho-metalated complexes were discussed. The dynamics of the hydrogen present in the coordination sphere of the metal was studied. The dihydrogen ligands was substituted easily and the corres

Full text of DOI:10.1021/om034259c

1424
Organometallics 2004, 23, 1424-1433
Or th o-Meta la ted Ru th en iu m Hyd r id o Dih yd r ogen
Com p lexes: Dyn a m ics, Exch a n ge Cou p lin gs, a n d
Rea ctivity
J ochen Matthes,†,‡ Stephan Gru¨ndemann,† Andrew Toner,‡ Yannick Guari,‡
Bruno Donnadieu,‡ J ohann Spandl,† Sylviane Sabo-Etienne,*,‡ Eric Clot,*,§
Hans-Heinrich Limbach,*,† and Bruno Chaudret*,‡
Institute of Chemistry, Freie Universita¨t Berlin, Takustrasse 3, D-14195 Berlin, Germany,
Laboratoire de Chimie de Coordination du CNRS, Universite´ Paul Sabatier, 205 route de
Narbonne, 31077 Toulouse Cedex 04, France, and Laboratoire de Structure et Dynamique des
Syste`mes Mole´culaires et Solides (UMR 5636), case courrier 14, Universite´ Montpellier II,
Place Euge`ne Bataillon, 34905 Montpellier Cedex, France
Received October 24, 2003
A series of ortho-metalated ruthenium hydrido dihydrogen complexes of the form RuH-
(H2)(X)(PiPr3)2 (X ) 2-phenylpyridine (ph-py) (2), benzoquinoline (bq) (3), phenylpyrazole
(ph-pz) (4)) were prepared by adding 1 equiv of the corresponding substrate X-H and 2
equiv of PiPr3 to Ru(COD)(COT) under 3 bar of H2. The analogous complex RuH(H2)(ph-
py)(PCy3)2 (1) was prepared by adding 1 equiv of 2-phenylpyridine to RuH2(H2)2(PCy3)2. The
ortho-metalated X ligand is coordinated to ruthenium via the nitrogen of one ring and the
ortho carbon of a second ring as a result of C-H activation. 2 and 3 were characterized by
X-ray diffraction. They are the first examples of complexes displaying exchange couplings
between the hydride and the dihydrogen ligands. NMR studies and DFT calculations are
used to understand this phenomenon. The series of ortho-metalated model complexes RuH-
(H2)(X)(PH3)2 was investigated by DFT at the B3PW91 level. The coherent (quantum-
mechanical) as well as the incoherent (classical) exchange rates have been determined by
line shape analysis, and the activation energies hardly depend on the nature of the X
ligand: Ea(coherent) ) ca. 10 kJ mol-1, Ea(incoherent) ) ca. 40 kJ mol-1 (ca. 50 kJ mol-1 by
DFT). The corresponding transition states (2q TSQE C-4q TSQE C) for the classical exchange
process have been located by DFT at the B3PW91 level. The dihydrogen ligand is now trans
to N and perpendicular to the plane of the chelating ligand. These states connect to the
isomer with the dihydrogen trans to C through coupled rotation of H2 and proton transfer
from H2 to H. The dihydrogen ligand can be substituted easily, and the corresponding
complexes RuH(L)(ph-py)(PiPr3)2 with L ) N2 (5), O2 (6), CO (7), C2H4 (8) have been isolated
and fully characterized by NMR and by crystal structure analyses in the case of 6 and 8.
The model systems RuH(L)(ph-py)(PH3)2 (5q-8q) have been optimized at the DFT level
(B3PW91). In the case of 8, we could not detect any ethylene insertion in either the Ru-H
or the Ru-C bond. Theoretical calculations explain the differences we observed with the
Murai type catalysts, which are highly reactive to ethylene insertion.
In tr od u ction
oped by Murai’s group represents a very interesting
example of such catalysis.3 C-C bond coupling of an
olefin with a functionalized aromatic compound is
achieved by chelating assistance, allowing ortho C-H
bond cleavage. Some of us have already shown that the
ortho-metalated ruthenium complexes RuH(H2)(o-C6H4-
COR)(PCy3)2 (R ) Me, Ph) resulting from C-H bond
activation of an arene ketone can indeed be isolated and
used as catalyst precursors for the ethylene insertion
into the ortho C-H bond of acetophenone or benzophen-
one at room temperature.4 The presence of an η2-
dihydrogen ligand in the complex may be at the origin
The functionalization of C-H bonds is a problem of
both academic and industrial importance.1 Different
routes have been presently explored for achieving this
goal catalytically by using molecular transition-metal
catalysts. They include early transition metals and
electrophilic or nucleophilic systems with late transition
metals.2 In this context, the system extensively devel-
* To whom correspondence should be addressed. E-mail: sabo@lcc-
toulouse.fr (S.S.-E.).
† Freie Universita¨t Berlin.
‡ Universite´ Paul Sabatier.
§ Universite´ Montpellier II.
(3) (a) Murai, S.; Kakiuchi, F.; Sekine, S.; Tanaka, Y.; Kamatani,
A.; Sonoda, M.; Chatani, W. Nature 1993, 366, 529. (b) Kakiuchi, F.;
Murai, S. Acc. Chem. Res. 2002, 35, 826.
(4) (a) Guari, Y.; Sabo-Etienne, S.; Chaudret, B. J . Am. Chem. Soc.
1998, 120, 4228. (b) Guari, Y.; Castellanos, A.; Sabo-Etienne, S.;
Chaudret, B. J . Mol. Catal., in press.
(1) Labinger, J . A.; Bercaw, J . E. Nature 2002, 417, 507.
(2) (a) J ia, C.; Kitamura, T.; Fujiwara, Y. Acc. Chem. Res. 2001, 34,
633. (b) Ritleng, V.; Sirlin, C.; Pfeffer, M. Chem. Rev. 2002, 102, 1731.
(c) Guari, Y.; Sabo-Etienne, S.; Chaudret, B. Eur. J . Inorg. Chem. 1999,
1047. (d) Dyker, G. Angew. Chem., Int. Ed. Engl. 1999, 38, 1698.
10.1021/om034259c CCC: $27.50 © 2004 American Chemical Society
Publication on Web 02/14/2004

Ortho-Metalated Ru Hydrido Dihydrogen Complexes
Organometallics, Vol. 23, No. 6, 2004 1425
Ta ble 1. Cr ysta l Da ta for 2, 3, 6, a n d 8
2
3
6
8
chem formula
formula wt
C
29H50NP2Ru
C31H53NP2Ru
602.75
C29H51NO2P2Ru
608.72
C31H55NP2Ru
604.77
575.71
cryst syst
orthorhombic
Pbcn
4; 1.297
0.657
triclinic
P1h
2; 1.319
0.642
monoclinic
P21/n
4; 1.306
0.634
triclinic
P1h
2; 1.282
space group
Z; calcd density, Mg/m3
abs coeff, mm-1
0.622
F(000)
a, Å
b, Å
c, Å
1220
640
1288
644
8.6468(13)
19.014(3)
17.927(3)
10.214(3)
10.919(3)
14.553(4)
85.05(3)
76.78(3)
73.85(3)
1517.3(7)
113(2)
12.251(3)
19.468(3)
13.042(4)
9.8610(6)
10.3982(6)
16.2667(10)
80.7480(10)
84.8190(10)
72.3510(10)
1567.22(16)
183(2)
R, deg
â, deg
95.54(3)
γ, deg
V, Å3
2947.4(8)
150(2)
3096.0(12)
180(2)
temp, K
no. of data/restraints/params
goodness of fit on F2
R1 (I > 2σ(I))
2332/0/156
1.231
0.0374
0.0925
0.689 and -0.462
4513/0/340
1.150
0.0304
0.0737
0.439 and -0.398
4821/0/332
1.053
0.0305
0.0583
0.312 and -0.359
8962/0/349
1.070
0.0238
0.0581
0.457 and -0.250
wR2
largest diff peak and hole, e Å-3
Ch a r t 1. Str u ctu r es of Or th o-Meta la ted Hyd r id o
Dih yd r ogen Com p lexes 2-4 a n d Nu m ber in g of
P r oton s a n d Ca r bon s in th e Liga n d s
of the ease of this reaction. In an attempt to gain better
knowledge of the mechanism of C-H activation and
carbon-carbon bond formation in such compounds, we
have undertaken a systematic study of hydrogen ex-
change in these and related systems. We have already
published preliminary results on the hydrido dihydrogen
complexes RuH(H2)(ph-py)(PR3)2 (R ) Cy (1), iPr (2); ph-
py ) o-C6H4C5H4N), containing an ortho-metalated
phenylpyridyl ligand, and shown that protonation leads
to a complex accommodating a dihydrogen ligand and
a weak agostic C-H bond in equilibrium with a dihy-
drogen ortho-metalated complex.5
We now report the full characterization of compounds
1 and 2 and of derivatives similar to 2 but containing
metalated 7,8-benzoquinoline (bq) or 1-phenylpyrazole
(ph-pz). The dynamics of the hydrogens (hydride and
dihydrogen ligand) present in the coordination sphere
of the metal are described in each case, by combining
NMR studies and DFT calculations. Moreover, we show
that the dihydrogen ligand in 2 is easily substituted,
as illustrated by the reactivity of 2 with ethylene,
dioxygen, dinitrogen, and carbon monoxide.
complexes, namely RuH(H2)(bq)(PiPr3)2 (3) and RuH-
(H2)(ph-pz)(PiPr3)2 (4) (see Chart 1), were also prepared
in the same way.
The new complexes 1-4 were characterized by mi-
croanalysis and NMR data. Their full characterization
is given in the Experimental Section. Complexes 2 and
3 were also characterized by X-ray analysis (see Tables
1 and 2). The complexes display a distorted-octahedral
environment with two trans phosphine ligands (P-
Ru-P angle ca. 165°) and, in the equatorial plane, the
metalated ligand (ph-py for 2 and bq for 3). The hydride
and dihydrogen ligands were located in the case of 3
(see Figure 1). In the case of 2, some disorder prevented
the localization of the carbon and the nitrogen atoms
bound to the ruthenium and thus the localization of the
hydrides.
Localization of hydrogen atoms by X-ray measure-
ments7 is always subject to debate, and in the field of
polyhydride chemistry, computational studies have
proved to be a very efficient means to obtain structural
information and, particularly, to locate hydrides se-
curely.8 We have thus carried out DFT calculations
(B3PW91) on the model systems RuH(H2)(ph-py)(PH3)2
(2q), RuH(H2)(bq)(PH3)2 (3q; see Figure 1), and RuH-
(H2)(ph-pz)(PH3)2 (4q), where the only simplification lies
in the nature of the phosphine ligand. For the phen-
ylpyridine complex 2q, the calculated geometry (Table
2) confirms the presence of a dihydrogen ligand trans
to the ortho-metalated C (with a H(2)-H(3) bond
distance of 0.905 Å). Due to the hydride cis effect,9 the
Ru-H(3) bond distance is shorter than the Ru-H(2)
Resu lts a n d Discu ssion
Syn th esis a n d P r op er ties of Neu tr a l Hyd r id o
Dih yd r ogen Or th o-Meta la ted Com p lexes. The reac-
6
tion of RuH2(H2)2(PCy3)2 with phenylpyridine (H-ph-
py) affords the metalated species RuH(H2)(ph-py)(PCy3)2
(1). Complex 1 was found to be insufficiently soluble for
full NMR characterization and recrystallization. We
thus looked for an alternative preparation leading to a
similar but more soluble derivative. We chose to use Pi-
Pr3 as an ancillary ligand and reacted in one pot Ru-
(COD)(COT) (COD ) 1,5-C8H12; COT ) 1,3,5-C8H10
)
with 1 equiv of H-ph-py and 2 equiv of PiPr3 in pentane
under 3 bar of dihydrogen. The product, RuH(H2)(ph-
py)(PiPr3)2 (2), was shown to display spectroscopic
features very similar to those of 1. The corresponding
benzoquinoline (H-bq) and 1-phenylpyrazole (H-ph-pz)
(5) Toner, A. J .; Gru¨ndemann, S.; Clot, E.; Limbach, H.-H.; Don-
nadieu, B.; Sabo-Etienne, S.; Chaudret, B. J . Am. Chem. Soc. 2000,
122, 6777.
(6) (a) Sabo-Etienne, S.; Chaudret, B. Coord. Chem. Rev. 1998, 178-
180, 381. (b) Borowski, A. F.; Sabo-Etienne, S.; Christ, M. L.; Don-
nadieu, B.; Chaudret, B. Organometallics 1996, 15, 1427. (c) Borowski,
A. F.; Donnadieu, B.; Daran, J .-C.; Sabo-Etienne, S.; Chaudret, B.
Chem. Commun. 2000, 543.
(7) Zhao, D.; Bau, R. Inorg. Chim. Acta 1998, 269, 601.
(8) (a) Maseras, F.; Lledo´s, A.; Clot, E.; Eisenstein, O. Chem. Rev.
2000, 100, 601. (b) Atheaux, I.; Delpech, F.; Donnadieu, B.; Sabo-
Etienne, S.; Chaudret, B.; Hussein, K.; Barthelat, J .-C.; Braun, T.;
Duckett, S. B.; Perutz, R. N. Organometallics 2002, 21, 5347.

1426 Organometallics, Vol. 23, No. 6, 2004
Matthes et al.
F igu r e 1. X-ray crystal structure of RuH(H2)(bq)(PiPr3)2 (3) and calculated structure for the model system RuH(H2)(bq)-
(PH3)2 (3q).
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles (d eg) for th e Th r ee Molecu la r Dih yd r ogen Com p lexes
(2q, 3q, a n d 4q) a n d th e Cor r esp on d in g Tr a n sition Sta tes for Cla ssica l H/H2 Exch a n ge (2qTSQEC, 3qTSQEC
,
a n d 4qTSQEC) Op tim ized a t th e B3P W91 Level w ith th e Ca lcu la ted Activa tion En er gy ∆Eq (k J m ol-1) a n d
Com p a r ison w ith th e X-r a y Da ta of 2 a n d 3
2 (X-ray)
2q
2qTSQEC
3 (X-ray)
3q
3qTSQEC
4q
4qTSQEC
Ru-H(1)
Ru-H(2)
Ru-H(3)
H(1)-H(2)
H(2)-H(3)
Ru-C
1.609
1.728
1.700
1.977
0.905
2.063
2.174
2.293
1.693
1.687
1.693
0.877
2.401
2.094
2.086
2.298
1.54(4)
1.57(5)
1.68(4)
1.75(6)
1.605
1.726
1.697
1.968
0.905
2.069
2.192
2.293
1.689
1.682
1.689
0.880
2.406
2.106
2.095
2.298
1.606
1.723
1.700
1.987
0.903
2.073
2.163
2.294
1.686
1.674
1.686
0.881
2.373
2.117
2.064
2.302
0.82(6)
2.135(3)
2.135(3)
2.3392(8)
2.104(3)
2.155(3)
2.3562(11)
2.3334(11)
164.51(3)
Ru-N
Ru-P
P-Ru-P
∆Eq
165.65(4)
165.2
55.7
163.4
165.9
53.4
163.5
164.4
54.5
165.6
2
distance (1.700 vs 1.728 Å), but the computed H(1)‚‚‚
H(2) distance of 1.977 Å is too long for a bonding
interaction. For 2q, no local minimum with H2 trans to
N could be located on the potential energy surface. All
attempts yielded the dihydrogen complex with H2 trans
to C. This reflects the unfavorable situation of two
strong σ-donor groups mutually trans (C and H). This
bonding pattern is also observed for 3q (4q), where the
H2 ligand trans to C has an H-H bond distance of 0.905
Å (0.903 Å). As shown in Table 2, the geometries around
the transition-metal center are very similar for the three
complexes 2q-4q. This may explain their similar
spectroscopic behavior.
The most salient spectroscopic feature of compounds
1-4 is the presence at room temperature of a high-field
peak in the 1H NMR spectrum integrated for three
protons and corresponding to the hydride and dihydro-
gen ligands in exchange near -8.5 ppm for complexes
1-3 and at -9.2 ppm for complex 4. The ortho-
metalated ligand is predominantly characterized by low-
field doublets for H1 and H10 between 8 and 10 ppm
(the corresponding proton in complex 4 being H8). The
remaining signals have chemical shifts and multiplici-
ties similar to those of the uncoordinated ligand. In the
31P{1H} NMR spectrum, a single signal is observed for
the two equivalent trans phosphorus atoms at 46 ppm
for the bis(tricyclohexylphosphine) complex 1 and near
58 ppm for the bis(triisopropylphosphine) complexes
2-4. In the 13C NMR spectra, the most salient charac-
teristic is the ortho-metalated carbon resonance. It
appears as a triplet shifted to 197, 195, and 176 ppm in
complexes 2-4, respectively, with a J CP coupling of 11
Hz. In addition, NMR investigations between 293 and
163 K in THF-d8 solutions demonstrate the presence of
both quantum-mechanical (coherent)10 and classical
(incoherent) exchange processes between the hydrogen
atoms present in the coordination sphere of complexes
2-4. The superimposed experimental and calculated
spectra of the hydride region at selected temperatures
are shown in Figure 2. The spectra are similar for all
three complexes. At room temperature a single line is
observed for all three hydrogen nuclei. As the temper-
ature is decreased, this line broadens and splits into a
doublet and triplet due to an AB2 spin system displaying
unusually large H-H coupling constants (between 300
and 400 Hz at 213 K) resulting from quantum-mechan-
ical exchange. At 183 K, the triplet changes into a triplet
of triplets as coupling to the two equivalent phosphorus
atoms is resolved. As the two hydrogen atoms in the
dihydrogen ligand are magnetically equivalent, the line
1
shape in the H NMR spectra depends on the chemical
shifts ν1 and ν2 of the two hydrogen sites, corresponding
respectively to the hydride and the dihydrogen ligands,
the exchange coupling J 12 between the hydride and the
dihydrogen ligand, and the rate constant k12. Further-
more, the scalar coupling constant of the hydride ligand
with the two magnetically equivalent phosphorus atoms
J HP is resolved at lower temperatures. The scalar
coupling between the protons of the dihydrogen ligand
and the phosphorus atoms was not resolved and there-
fore neglected. The relaxation time T1 values are given
in the Experimental Section and are in agreement with
the presence of a dihydrogen ligand.
(9) Van der Sluys, L. S.; Eckert, J .; Eisenstein, O.; Hall, J . H.;
Huffman, J . C.; J ackson, S. A.; Koetzle, T. F.; Kubas, G. J .; Vergamini,
P. J .; Caulton, K. G. J . Am. Chem. Soc. 1990, 112, 4831.
(10) Sabo-Etienne, S.; Chaudret, B. Chem. Rev. 1998, 98, 2077.

Ortho-Metalated Ru Hydrido Dihydrogen Complexes
Organometallics, Vol. 23, No. 6, 2004 1427
1
F igu r e 2. Superimposed experimental and calculated H NMR (500 MHz) spectra of the hydride region of 2-4 at selected
temperatures.
The dependence on temperature of the parameters of
the rotational coherent and incoherent exchange rates
in 2-4 can be expressed by the Arrhenius type equation
k ) A exp(-Ea/RT)
where k is the corresponding exchange rate, either the
incoherent chemical exchange rate k12 or the coherent
quantum-mechanical exchange rate πJ 12. A is the
frequency factor, Ea is the activation energy of the
observed process, R is the ideal gas constant (8.31
J /(mol‚K)), and T is the temperature.
For compound 2 πJ 12 ) 105.6(0.4 exp((-10.1 ( 1.0 kJ
mol-1)/RT) Hz (173 K e T e 213 K; J 12 ) 380 Hz at
213 K) and k12 ) 1012.7 ( 0.1 exp((-40.0 ( 1.2 kJ mol-1)/
RT) s-1 (183 K e T e 263 K; k12 ) 680 s-1 at 213 K).
F igu r e 3. Arrhenius plots of the coherent (b) and incoher-
For compound 3 πJ 12 ) 105.6(0.3 exp((-10.7 ( 1.3 kJ
ent (9) exchange between the hydride and the dihydrogen
mol-1)/RT) Hz (173 K e T e 213 K; J 12 ) 320 Hz at
ligand in 2-4.
213 K) and k12 ) 1013.1(0.2 exp((-42.3 ( 0.8 kJ mol-1)/
RT) s-1 (183 K e T e 263 K; k12 ) 540 s-1 at 213 K).
For compound 4 πJ 12 ) 106.4(0.3 exp((-13.8 ( 1.0 kJ
mol-1)/RT) Hz (173 K e T e 213 K; J 12 ) 310 Hz at
213 K) and k12 ) 1013.3(0.1 exp((-42.0 ( 0.8 kJ mol-1)/
RT) s-1 (183 K e T e 263 K; k12 ) 1050 s-1 at 213 K).
The Arrhenius diagrams of the coherent and incoher-
ent exchanges of the three complexes are plotted in the
same graph in Figure 3.
Complexes 1-4 are the first known examples of
complexes in which both the incoherent (classical) and
the coherent (quantum-mechanical) exchange between
a hydride and a dihydrogen ligand can be observed
experimentally. The exchange in these compounds can
be described by simple Arrhenius equations. As ex-
pected, the activation energy of the coherent exchange
is much smaller than that of the classical chemical
exchange. The activation energies of the classical ex-
change process in the three complexes is hardly de-
pendent upon the complex and is found near 40 kJ
mol-1, whereas the activation energies of the coherent
process are in the range of 10 kJ mol-1
.
We have calculated by DFT at the B3PW91 level the
transition states (TS) for the classical exchange process
between H and H2. 2qTSQEC-4qTSQEC, respectively, have
been located, and they can be described as molecular
dihydrogen complexes with the H2 ligand trans to N and
perpendicular to the plane of the chelating ligand
(Figure 4 for 2qTSQEC). The transition states are not
associated with rotation of the H2 ligand trans to N but
connect to the isomer with the dihydrogen trans to C
(2q -4q , respectively) through coupled rotation of H2
and proton transfer from H2 to H. This exchange process
is sufficient to achieve permutation of two identical
particles between H and H2, which is a necessary

1428 Organometallics, Vol. 23, No. 6, 2004
Matthes et al.
Sch em e 1. Su bstitu tion of th e Dih yd r ogen Liga n d
in Ru H(H2)(p h -p y)(P iP r 3)2 (2) by N2 (5), O2 (6), CO
(7), a n d C2H4 (8)
F igu r e 4. Calculated geometry for the transition state
2qTSQEC, corresponding to the hydrogen scrambling be-
tween H and H2 in 2q. See Table 2 for selected bond lengths
and angles.
condition to observe quantum exchange couplings.10 The
geometry around the transition-metal center is not
greatly modified during the exchange (Table 2). The
main changes are an increase of the Ru-C bond
distance and a shortening of the Ru-N distance to
respond to the change in nature of the corresponding
trans ligands (H2 f H for C and H f H2 for N).
The calculated activation barriers, ∆Eq, overestimate
the corresponding experimental values, Ea, by 10 kJ
mol-1 (Table 2). However, the three calculated values
are very close, as is the case for the experimental data.
The discrepancy between calculated and experimental
barriers could originate from the highly unfavorable
C-Ru-H linear geometry in the transition state, where
two strong σ-electron donor groups are mutually trans.
In the real systems, C-H‚‚‚H-Ru interactions between
the hydride and dangling bonds within the phosphine
ligands may develop and stabilize the TS with respect
to the ground state.11
The very unusual observation of quantum exchange
coupling between hydride and dihydrogen is due to the
small reorganization of the molecular geometry during
the exchange process (Table 2). This can be traced not
only to the chelate nature of the ligands used but also
to the nonexistence of the dihydrogen complex isomer
with H2 cis to C as an intermediate along the exchange
pathway (shorter tunneling path). Of importance also
is the destabilizing nature of the C-Ru-H linear
bonding pattern in the TS, leading to an activation
barrier for H scrambling of 40 kJ mol-1. This is
sufficiently high both to be observed by NMR and to
delay the onset of incoherent exchange, so as to have
observable coherent exchange.
Ta ble 3. Com p a r ison of th e Exp er im en ta l a n d
Ca lcu la ted Va lu es of Selected Bon d Dista n ces (Å)
a n d An gles (d eg) for th e Dioxygen (6 a n d 6q) a n d
Eth ylen e (8 a n d 8q) Com p lexes
6
6q
8
8q
Ru-C
Ru-N
Ru-P
2.084(3)
2.140(3)
2.3832(10)
2.3905(10)
1.63(3)
2.069
2.141
2.319
2.0895(14)
2.2169(12)
2.3847(4)
2.3724(4)
1.47(2)
2.075
2.210
2.294
Ru-H
1.582
1.593
1.402
C-C
1.395(2)
O-O
1.407(3)
162.49(3)
76.77(11)
1.378
169.9
77.2
P-Ru-P
N-Ru-C
161.585(14)
76.80(5)
160.0
77.2
with the hydride trans to the nitrogen of the phenylpyr-
idyl group and cis to L. The most salient spectroscopic
features are the hydride signal in 1H NMR and the
metalated carbon in 13C NMR, the chemical shifts
depending upon the nature of L. Thus, the hydride is
found at -12.04 ppm (J P-H ) 25.3 Hz) for 5, -3.10 ppm
(J P-H ) 19.6 Hz) for 6, -12.87 ppm (J P-H ) 24.7 Hz)
for 7, and -10.87 ppm (J P-H ) 24.8 Hz) for 8. The values
are very similar, except for the O2 complex; precedents
for low-field shifts of the hydride upon O2 coordination
are known.12 The metalated carbons are coupled to
phosphorus and resonate at 191.1 ppm (J P-C ) 13 Hz)
for 5, 193.4 ppm (J P-C ) 9 Hz) for 6, 191.4 ppm (J P-C
)
13 Hz) for 7, and 199.3 ppm (J P-C ) 12 Hz) for 8. In
the case of 8, we could observe a fluxional behavior
which involves both the phosphine and the ethylene
ligands. Ethylene was characterized at room tempera-
ture by a broad singlet at 2.51 ppm in the 1H NMR
spectrum and at 47.0 ppm in the 13C NMR spectrum.
The 1H NMR signal shifts to 2.42 ppm at 215 K and
decoalesces at lower temperatures into two signals at
2.52 and 2.28 ppm. The activation energy of the rotation
process was calculated to be 45.9 kJ mol-1, which is in
the range found for other ethylene complexes.13
R ea ct ivit y St u d ies: Dih yd r ogen Su b st it u t ion .
The dihydrogen ligand in 2 can easily be substituted to
give the new complexes RuH(L)(ph-py)(PiPr3)2 (L ) N2
(5), O2 (6), CO (7), C2H4 (8)), simply by bubbling the
corresponding gas into a pentane solution of 2 (Scheme
1). Complexes 5-8 were fully characterized by mi-
croanalysis and spectroscopic methods (see the Experi-
mental Section). In addition, 6 and 8 were characterized
by X-ray analysis (Tables 1 and 3). It should be noted
that solutions of 8 are only stable under an atmosphere
of ethylene. All complexes display the same structure
The structural data found for 6 and 8 are very similar
to those found for 2 (see Figures 5 and 6). Each complex
adopts a slightly distorted octahedral geometry (P-
Ru-P angle near 162° in each case), the hydride being
(12) (a) J imenez-Tenorio, M.; Puerta, M. C.; Valerga, P. J . Am.
Chem. Soc. 1993, 115, 9794. (b) J imenez-Tenorio, M.; Puerta, M. C.;
Valerga, P. Inorg. Chem. 1994, 33, 3515.
(11) Richardson, T. B.; Koetzle, T. F.; Crabtree, R. H. Inorg. Chim.
Acta 1996, 250, 69.
(13) Cramer, R.; Kline, J . B.; Roberts, J . D. J . Am. Chem. Soc. 1969,
91, 2519.

Ortho-Metalated Ru Hydrido Dihydrogen Complexes
Organometallics, Vol. 23, No. 6, 2004 1429
Ta ble 4. Selected Bon d Dista n ces (Å) for th e
Com p lexes Ru H(L)(p h -p y)(P H3)2 (L ) H2 (2q), N2
(5q), O2 (6q), CO (7q), C2H4 (8q)) a n d ∆Eb Bon d in g
En er gies (k ca l m ol-1) of th e Differ en t L Liga n d s to
th e F r a gm en t Ru H(p h -p y)(P H3)2
2q
5q
6q
7q
8q
Ru-C
Ru-N
Ru-H
∆Eb
2.063
2.174
1.610
88.3
2.060
2.174
1.611
98.5
2.069
2.141
1.582
103.4
2.110
2.179
1.606
215.6
2.075
2.210
1.647
116.4
the various ligands range from 88.3 kJ mol-1 (H2, 2q)
to 215.6 kJ mol-1 (CO, 7q), and the dihydrogen complex
is the least stable (Table 4). The substitution of H2 by
the L ligand is thus thermodynamically favored for all
the ligands considered. The Ru-C bond distance trans
to the incoming ligand L tends to slightly increase with
the binding energy ∆Eb, in agreement with the presence
of stronger σ-donor ligands (Table 4). The other bonds
around the metal center are not altered in a similar
fashion. The Ru-H and Ru-N bond distances are not
correlated with each other. 8q exhibits both a long
Ru-H bond (1.647 Å) and a long Ru-N bond (2.210 Å),
while the opposite is observed for 6q (short Ru-H, 1.582
Å; short Ru-N, 2.141 Å).
F igu r e 5. X-ray crystal structure of RuH(O2)(ph-py)(Pi-
Pr3)2 (6).
The dihydrogen ligand can be eliminated by refluxing
2 in THF to form the new species 9. This complex can
also be formed by slow loss of ethylene from 8 in a THF
solution. 9 is very air-sensitive and immediately reacts
with H2, N2, O2, CO, or C2H4 to give the corresponding
complexes 2 and 5-8. It has not been possible to isolate
it, and therefore, 9 has only been characterized in
solution. Complex 9 is not fluxional; it shows a hydride
signal at -10.95 ppm (J P-H ) 26.4 Hz) and a metalated
carbon at 185.0 ppm (J P-C ) 11.6 Hz). 9 may be a 16-
electron species or a complex resulting from the sub-
stitution of H2 or C2H4 by THF. In view of the similarity
of the spectroscopic properties of 9 with those of 2 and
5-8 and of its absence of fluxionality, we propose for 9
the 18-electron structure RuH(THF)(ph-py)(PiPr3)2.
F igu r e 6. X-ray crystal structure of RuH(C2H4)(ph-py)(Pi-
Pr3)2 (8).
trans to nitrogen. The Ru-C and Ru-N distances for
the metalated phenylpyridyl ligands seem little affected
by the trans ligand; they are respectively 2.135(3) Å
(average values due to disorder) for 2, 2.084(3) and
2.140(3) Å for 6 and 2.0895(14) and 2.2169(12) Å for 8.
In the case of 6, the O-O distance is 1.407(3) Å,
significantly longer than in free dioxygen (1.2074 Å) but
similar to that in other dioxygen ruthenium com-
plexes.12,1414 Remarkably, the hydride and the dioxygen
ligand adopt a cis configuration, as previously reported
in the rhodium complex RhH(O2){CH2dC(CH2CH2Pt-
Bu2)2}.15 Finally the C-C distance in the ethylene
ligand of 8 is also elongated (1.395(2) Å) compared to
uncoordinated ethylene (1.33 Å).
The model systems RuH(L)(ph-py)(PH3)2 (L ) N2 (5q),
O2 (6q), CO (7q), C2H4 (8q)) have been optimized at the
DFT level (B3PW91), and for 6q and 8q the agreement
with the experimental data is excellent (Table 3). The
geometry of the 16-electron fragment RuH(ph-py)(PH3)2
(A), with no ligand trans to C, has been optimized. The
structure of A is that of an octahedron lacking one
ligand trans to C. The binding energies, ∆Eb, to A of
This series of experiments demonstrates (i) that the
exchange process in the hydrido dihydrogen derivatives
is not highly dependent upon the structure of the
metalated ligand and, in particular, it is not affected
by the rigidity of the benzoquinoline ligand and (ii) that
the dihydrogen ligand is readily substituted by many
different ligands. Of special interest are the dioxygen
complex, one of the few cis hydrido dioxygen compounds
known, and the ethylene complex. In the latter com-
pound, no evidence has been found for the insertion of
ethylene either into the Ru-H or into the Ru-C bond.
This contrasts with what is observed in the correspond-
ing complexes RuH(H2)(OdC(R)C6H4)(PR3)2, which have
been shown to catalyze the insertion of ethylene into
the C-H bond of an aromatic ketone at room temper-
ature.4
To gain a better understanding of the absence of
reaction of the ethylene complex 8, we have searched
for a possible reaction mechanism. The ethylene com-
plex 8q′ with the ethylene ligand cis to C has been
optimized, and it is less stable than 8q by only 26 kJ
mol-1. This intermediate is on the pathway for the C-C
bond coupling process, and its energy relative to 8q is
not high enough to explain the absence of reaction.
However, the isomerization of 8q to 8q ′ would most
(14) J ia, G.; Sang Ng, W.; Chu, H. S.; Wong, W.-T.; Yu, N.-T.;
Williams, I. D. Organometallics 1999, 18, 3597 and references therein.
(15) Vigalok, A.; Shimon, L. J . W.; Milstein, D. J . Chem. Soc., Chem.
Commun. 1996, 1673.

1430 Organometallics, Vol. 23, No. 6, 2004
Matthes et al.
Sch em e 2. Isom er iza tion of th e Eth ylen e
necessary to exchange the hydride with one of the
dihydrogen protons. The dihydrogen ligand in these
complexes may readily be substituted by dinitrogen,
dioxygen, carbon monoxide, or ethylene. Remarkably,
ethylene does not insert either into the Ru-H or into
the Ru-C bond. The computational studies have al-
lowed us not only to ascertain the location of the hydride
and dihydrogen ligands in the different complexes but
also to fully understand the mechanism of the exchange
process and to highlight the importance of the chelating
assistance in the catalytic cycle for the Murai reaction
and of the interplay of the mutually trans ligands.
Com p lexes 8q a n d 8q′
Exp er im en ta l Section
All reactions were carried out under argon by using
Schlenk glassware and vacuum-line or glovebox tech-
niques. All solvents were freshly distilled from standard
drying agents and thoroughly degassed under argon
before use. Microanalyses were performed by the Labor-
atoire de Chimie de Coordination Microanalytical Ser-
likely occur first through dissociation of C2H4, which
requires 116.4 kJ mol-1. The 16-electron complex A with
the hydride trans to N has then to isomerize to the 16-
electron complex B with the hydride cis to N (Scheme
2). The reaction energy associated to the A f B
isomerization is +77.3 kJ mol-1 with an activation
energy of 80.1 kJ mol-1. The strong endothermicity of
the transformation A f B is a consequence of the
unfavorable linear C-Ru-H geometry in B, where two
strong σ-electron donor groups are mutually trans.
Thus, the activation energy for the transformation 8q
f 8q′ amounts to 196.5 kJ mol-1, which is the sum of
the dissociation energy of C2H4 from 8q and the activa-
tion energy for the isomerization of the 16-electron
complex A. The transition state 8q′TS for ethylene
insertion into the Ru-H bond from 8q′ has been located
and lies 54.5 kJ mol-1 above 8q′. Although the insertion
mechanism is not too high in energy, the rate-determin-
ing step is the isomerization of 8q to 8q′ and this process
is too endothermic. We have tried to locate a transition
state for ethylene insertion into Ru-H from 8q leading
to an ethyl complex, but all our attempts have failed.
The trans configuration of the two Ru-C bonds in the
TS would be highly destabilizing. All these observations
tend to indicate that, in the catalytic cycle for the Murai
reaction, the interplay of the nature of the mutually
trans ligands plays a critical role. In Murai’s system,
the ketone group in acetophenone is certainly essential
to induce selective ortho metalation of the phenyl ring.3
However, the reaction can only proceed, and particularly
achieve C-C coupling, through a low-energy pathway
displaying an intermediate complex with ethylene cis
to the ortho-metalated carbon. One possibility could be
decoordination of the ketone group, hence creating a
vacant site cis to the aryl group. The dissociation of the
orienting group is certainly easier for a ketone than for
pyridine. Strong coordination of pyridine might explain
the absence of reaction in the phenylpyridine case.
1
vice. H (200.13, 250.13, 300.13, or 500.13 MHz), 13C
(125.70 MHz), and 31P NMR spectra (201.46 MHz) were
recorded on Bruker or Varian instruments operating in
the Fourier transform mode. Tetrahydrofuran-2H8 used
for NMR analysis was distilled before use and thor-
oughly degassed during four freezing, thawing, and
degassing cycles. All NMR samples were prepared in
either flame-sealed (ca. 10-6 mbar) or Teflon-stoppered
NMR tubes. RuCl3‚3H2O was purchased from J ohnson
Matthey Ltd. RuH2(H2)2(PCy3)2 was prepared according
to the procedure described in ref 6b.
Ru H(H2)(p h -p y)(P Cy3)2 (1). To a suspension of
RuH2(H2)2(PCy3)2 (265 mg, 0.40 mmol) in 20 mL of
pentane was added 2-phenylpyridine (74 µL, 0.52 mmol)
at room temperature. The reaction was allowed to
proceed for 24 h, during which time an orange solid
precipitated. This orange precipitate was filtered off,
washed with 20 mL of pentane, and dried in vacuo.
Yield: ca. 86%. Anal. Calcd for RuC47H77P2N: C, 68.91;
1
H, 9.47; N, 1.71. Found: C, 68.23; H, 9.54; N, 1.67. H
NMR (400.13 MHz, C6D6, 296 K; δ): -8.44 (br, 3H,
1
RuH(H2)); 1.11-2.33 (m, 66H, PCy3); 6.57 (t, 1H, J HH
1
1
) 6.0 Hz), 7.19 (t, 1H, J HH ) 8.6 Hz), 7.21 (t, 1H, J HH
1
) 7.6 Hz), 7.35 (m, 1H), 7.75 (d, 1H, J HH ) 8.4 Hz),
7.91 (d, 1H, 1J HH ) 7.4 Hz), 8.61 (d, 1H, 1J HH ) 7.4 Hz)
(all for ph-py); 9.62 (d, 1H, 1J HH ) 5.9 Hz, H1). 31P{1H}
NMR (81. 01 MHz, C6D6, 296 K; δ, ppm): 46.4 (s). T1
(400.13 MHz, THF-d8): 293 K, δ-8.8 25 ms; 170 K, δ-6.9
873 ms, δ-13.0 1061 ms; 183 K, δ-6.9 105 ms, δ-12.9 267
ms.
Ru H(H2)(p h -p y)(P iP r 3)2 (2). A solution of Ru(COD)-
(COT) (1; 80 mg, 0.25 mmol) with 2 equiv of com-
mercially available triisopropylphosphine (97 µL, 0.50
mmol) and 1 equiv of 2-phenylpyridine (36 µL, 0.25
mmol) was filtered into a Fisher-Porter bottle and
afterward pressurized with 3 bar of H2 over 24 h at room
temperature. The solvent was eliminated under vacuum,
and the resulting red oil was dried for 12 h with a high-
vacuum pump. Then 10 mL of pentane was added,
whereby a red solid precipitated. After filtration the
filtrate was kept in the freezer at -20 °C for 12 h. The
resulting red crystals were collected. Yield: ca. 86%.
Anal. Calcd for RuC29H53P2N: C, 60.18; H, 9.23; N, 2.42.
Found: C, 59.83; H, 8.81; N, 2.43. 1H NMR (500.13
Su m m a r y
We have reported in this paper the synthesis of new
hydrido dihydrogen complexes containing an ortho-
metalated ligand (phenylpyridine, benzoquinoline, or
phenylpyrazole). These complexes display remarkable
spectroscopic properties: namely, they show exchange
couplings between the hydride and the dihydrogen
ligands. The origin of these couplings lies in the barrier

Ortho-Metalated Ru Hydrido Dihydrogen Complexes
Organometallics, Vol. 23, No. 6, 2004 1431
MHz, THF-d8, 293 K; δ): -8.82 (br, 3H, RuH(H2)), 0.84
(m, 18H, P(CHMe2)3), 1.01 (m, 18H, P(CHMe2)3), 1.78
(br, 3H, RuH3), 0.82 (m, 18H, P(CHMe2)3), 1.04 (m, 18H,
P(CHMe2)3), 1.70 (m, ∼6H, P(CHMe2)3, under solvent
1
1
(m, 6H, P(CHMe2)3), 6.71 (t, 1H, J HH ) 7.2 Hz, H8),
peak); 6.41 (t, 1H, J HH ) 2.05 Hz, H2), 6.68 (m, 2H,
6.74 (t, 1H, J HH ) 7.2 Hz, H9), 6.82 (t, 1H, J HH ) 6.4
H6/H7), 7.20 (dd, 1H, 1J HH ) 7.34 Hz, 1.2 Hz, H5), 7.92
1
1
1
1
Hz, H2), 7.53 (t, 1H, J HH ) 7.6 Hz, H3), 7.66 (d, 1H,
(d, 1H, J HH ) 6.75 Hz, H8), 7.96 (b, 1H, H3), 8.28 (d,
1
1
1J HH ) 7.6 Hz, H7), 7.87 (d, 1H, J HH ) 8.1 Hz, H4),
1H, J HH ) 1,8 Hz, H1). 31P{1H} NMR (201.46 MHz,
8.04 (d, 1H, J HH ) 6.9 Hz, H10), 9.42 (d, 1H, J HH
)
THF-d8, 298 K; δ): 57.65 (s). 13C{1H} NMR (125.70
MHz, THF-d8, 298 K; δ): 19.79 (s, P(CHMe2)3), 20.21
(s, P(CHMe2)3), 27.14 (t, J PC ) 8.8 Hz, P(CHMe2)3), 108.1
(s, C2), 111.6 (s, C6), 119.3 (s, C5), 120.13 (s, C7), 124.53
(s, C1), 124.57 (s, C8), 130.0 (s, C4), 144.18 (s, C3),
145.92 (s, C9), 176.37 (t, J PC ) 11.3 Hz, C9). T1 (500.13
MHz, THF-d8): 273 K, δ-9.2 51 ms; 183 K, δ-7.3 (d, 2H,
1
1
5.3 Hz, H1). 31P{1H} NMR (201.46 MHz, THF-d8, 293
K; δ): 57.61(s). 13C{1H} NMR (125.70 MHz, THF-d8, 293
K; δ): 20.0 (s, P(CHMe2)3), 20.4 (s, P(CHMe2)3), 27.2 (t,
J PC 8.9 Hz, P(CHMe2)3), 119.0 (s, C4), 119.4 (s, C8),
120.0 (s, C2), 124.1 (s, C7), 127.0 (s, C9), 134.3 (s, C3),
145.1 (s, C10), 145.8 (s, C6), 158.0 (s, C1), 167.0 (s, C5),
197.3 (t, J PC ) 10.9 Hz, C11).
J HH ) 86 Hz) 42 ms, δ-13.1 (tt, 1H, J HH ) 86 Hz, J HP
)
Ru H(H2)(bq)(P iP r 3)2 (3). A yellow pentane solution
(ca. 15 mL) of Ru(COD)(COT) (0.70 g, 2.22 mmol), 7,8-
benzoquinoline (0.40 g, 2.22 mmol), and PiPr3 (0.85 mL,
4.44 mmol) was filtered into a Fischer-Porter bottle and
pressurized, at room temperature, with dihydrogen (3
bar). The solution immediately became orange and then,
after stirring for a further 24 h, deep red. After attain-
ment of atmospheric pressure, decantation, and then
filtration into another Fisher-Porter bottle, the solution
was freeze-thawed and degassed. Concentration in
vacuo and refrigeration gave a sample of 3 suitable for
single-crystal X-ray diffraction analysis. Subsequent
concentration of the solvent and storage at room tem-
perature gave 3 as large red cubes. Removal of the
mother liquor by decantation and refrigeration gave an
additional crop of 3 as a microcrystalline solid. Total
yield: 1.2 g, 90%. Anal. Calcd for RuC31H53P2N: C,
61.79; H, 8.80; N, 2.33. Found: C, 61.78; H, 9.07; N,
19.4 Hz) 82 ms; 173 K, δ-7.3 (s, 2H) 56 ms, δ-13.1 (tt,
1H, J HH ) 54 Hz, J HP ) 21.7 Hz) 160 ms.
Ru H(N2)(ph -py)(P iP r 3)2 (5). N2 was bubbled through
a pentane solution (20 mL) of RuH(H2)[P(iPr)3]2(phpy)
(2; 150 mg, 0.25 mmol) until all pentane was evaporated
(10 min). The resulting green powder was dried in
vacuo. Yield: ca. 90%. Anal. Calcd for RuC29H51P2N3:
C, 57.60; H, 8.50; N, 6.95. Found: C, 57.74; H, 8.22; N,
1
6.26. H NMR (500.13 MHz, THF-d8, 293 K; δ): -12.04
(t, J PH ) 25.3 Hz, 1H, RuH), 0.83 (m, 18H, P(CHMe2)3),
1.16 (m, 18H, P(CHMe2)3), 2.06 (m, 6H, P(CHMe2)3),
6.69 (t, 1H, 1J HH ) 6.8 Hz, H8), 6.72 (dt, 1H, 1J HH ) 7.2
Hz, 2J HH ) 1.9 Hz, H9), 7.04 (t, 1H, 1J HH ) 6.4 Hz, H2),
1
7.59 (m, 2H, H3 and H7), 7.65 (d, 1H, J HH ) 6.8 Hz,
H4), 7.88 (d, 1H, 1J HH ) 8.1 Hz, H10), 9.24 (d, 1H, 1J HH
) 5.6 Hz, H1). 31P{1H} NMR (201.46 MHz, THF-d8, 293
K; δ): 48.69 ppm. 13C{1H} NMR (125.70 MHz, THF-d8,
293 K; δ): 19.4 (s, P(CHMe2)3), 19.9 (s, CHMe2)3), 26.4
(t, J PC ) 8.6 Hz, P(CHMe2)3), 119.1 (s, C4), 119.9 (s, C8),
120.2 (s, C2), 123.5 (s, C7), 127.2 (s, C9), 134.2 (s, C3),
143.8 (s, C10), 146.2 (s, C6), 152.0 (s, C1), 167.2 (s, C5),
191.1 (t, J PC ) 13.4 Hz, C11).
1
2.44. H NMR (500.13 MHz, THF-d8, 293 K; δ): -8.55
(br, 3H, RuH3), 0.69 (m, 18H, P(CHMe2)3), 0.95 (m, 18H,
P(CHMe2)3), 1.70 (m, 6H, P(CHMe2)3), 7.21 (m, 1H, H9),
1
7.26 (m, 2H, H2/H8), 7.47 (d, 1H, J HH ) 8.6 Hz, H5),
7.66 (d, 1H, 1J HH ) 8.6 Hz, H6), 8.06 (d, 1H, 1J HH ) 7.7
Ru H(O2)(ph -py)(P iP r 3)2 (6). O2 was bubbled through
a pentane solution (20 mL) of 2 (150 mg, 0.25 mmol)
for 5 min. The solution was kept at -20 °C for 24 h,
allowing the formation of hexagonal orange crystals.
Yield: ca. 90%. Anal. Calcd for RuC29H51P2NO2: C,
57.22; H, 8.44; N, 2.30. Found: C, 57.40; H, 8.58; N,
1
Hz, H3), 8.28 (d, 1H, J HH ) 6.7 Hz, H10), 9.73 (d, 1H,
1J HH ) 4.8 Hz, H1). 31P{1H} NMR (201.46 MHz, THF-
d8, 298 K; δ): 57.65 (s). 13C{1H} NMR (125.70 MHz,
THF-d8, 298 K; δ): 19.8 (s, P(CHMe2)3), 20.3 (s,
P(CHMe2)3), 27.3 (t, J PC ) 8.8 Hz, P(CHMe2)3), 118.0
(s, C8), 120.1 (s, C2), 123.1 (s, C5), 127.22 (s, C9), 127.59
(s, C4), 130.83 (s, C6), 133.22 (s, C3), 134.8 (s, C7), 142.1
(s, C10) 142.8 (s, C12), 155.8 (s, C1), 157.1 (s, C13), 195.0
(t, J PC 11.1 Hz, C11). T1 (500.13 MHz, THF-d8): 273 K,
δ-8.5 40.16 ms; 183 K, δ-6.6 (d, 2H, J HH ) 121 Hz) 40
ms, δ -12.6 (tt, 1H, J HH ) 121 Hz, J HP ) 21.4 Hz) 79 ms;
173 K, δ-6.6 (d, 2H, J HH ) 85 Hz) 51 ms, δ-12.6 (tt, 1H,
J HH ) 85 Hz, J HP ) 21.7 Hz) 178 ms.
1
2.33. H NMR (500.13 MHz, THF-d8, 293 K; δ): -3.10
(t, 1H, 2J PH ) 19.6 Hz, RuH), 0.80 (m, 18H, P(CHMe2)3),
1.05 (m, 18H, P(CHMe2)3), 1.87 (m, 6H, P(CHMe2)3),
1
1
6.81 (t, 1H, J HH ) 7.4 Hz, H8), 6.86 (t, 1H, J HH ) 7.2
1
Hz, H9), 7.18 (t, 1H, J HH ) 6.5 Hz, H2), 7.71 (t, 1H,
1J HH ) 7.6 Hz, H3), 7.78 (d, 1H, J HH ) 7.4 Hz, H7),
1
7.97 (d, 1H, 1J HH ) 8.1 Hz, H4), 8.38 (d, 1H, 1J HH ) 7.4
Hz, H10), 10.22 (d, 1H, J HH ) 5.1 Hz, H1). 31P{1H}
1
NMR (201.46 MHz, THF-d8, 293 K; δ): 32.72. 13C{1H}
NMR (125.70 MHz, THF-d8, 293 K; δ): 19.5 (s,
P(CHMe2)3), 20.2 (s, P(CHMe2)3), 24.0 (t, J PC ) 8.6 Hz,
P(CHMe2)3), 119.2 (s, C4), 120.2 (s, C8), 121.0 (s, C2),
124.8 (s, C7), 128.0 (s, C9), 136.2 (s, C3), 143.1 (s, C10),
Ru H(H2)(p h -p z)(P iP r 3)2 (4). A yellow pentane solu-
tion (ca. 10 mL) of Ru(COD)(COT) (0.70 g, 2.22 mmol),
1-phenylpyrazole (0.29 mL, 2.22 mmol), and PiPr3 (0.85
mL, 4.44 mmol) was filtered into a Fisher-Porter bottle
and pressurized, at room temperature, with dihydrogen
(3 bar). The mixture immediately became very pale
yellow. After it was stirred at room temperature for 24
h, the solution was worked up in a manner similar to
that described for 3 to yield an orange solution. Storage
at -20 °C overnight gave 4 as a pale yellow microcrys-
talline solid. Total yield: 1.0 g, 80%. Anal. Calcd for
RuC27H53P2N2: C, 57.04; H, 9.33; N, 4.93. Found (1):
C, 59.88; H, 8.61; N, 6.02. Found (2): C, 59.31; H, 8.59;
N, 5.89. 1H NMR (500.13 MHz, THF-d8, 293 K; δ): -9.22
146.5 (s, C6), 154.5 (s, C1), 165.5 (s, C5), 193.4 (t, J PC
9.2 Hz, C11).
)
Ru H(CO)(p h -p y)(P iP r 3)2 (7). Carbon monoxide was
bubbled into a pentane solution (20 mL) of 2 (364 mg,
0.63 mmol) for 5 min. The solvent was eliminated under
vacuum, and the resulting yellow powder was dried in
vacuo. Anal. Calcd for RuC30H51P2ON: C, 59.77; H, 8.68;
N, 2.29. Found: C, 59.58; H, 8.50; N, 2.32. IR (cm-1
Nujol): 1891 (Ru-CO). H NMR (500.13 MHz, THF-d8,
,
1

1432 Organometallics, Vol. 23, No. 6, 2004
Matthes et al.
293 K; δ): -12.87 (t, J PH ) 24.7 Hz, 1H, RuH), 0.83 (m,
18H, P(CHMe2)3), 1.15 (m, 18H, P(CHMe2)3), 2.06 (m,
6H, P(CHMe2)3), 6.81 (m, 2H, H8/H9), 6.96 (t, 1H, 1J HH
system (CCD Area detector) in the case of 8, both
equipped with an Oxford Cryosystems Cryostream
Cooler Device and using graphite-monochromated Mo
KR radiation (λ ) 0.710 73 Å). The final unit cell
parameters were obtained by least-squares refinement
of a set of 8000 well-measured reflections, and crystal
decay was monitored by measuring 200 reflections by
image. No significant fluctuation of the intensities was
observed. An empirical absorption correction was per-
formed using SADABS16 (for complex 8). Structures
were solved by means of direct methods using the
program SIR9217 and refined by least-squares proce-
dures on F2 using the program SHELXL-97,16 included
in the WINGX18 version 1.64 05. The atomic scattering
factors were taken from ref 19. All hydrogen atoms were
located on a difference Fourier map, but they were
introduced in the refinement as fixed contributors using
a riding model with an isotropic thermal parameter
fixed at 20% higher than those of the C(sp2) atoms and
50% higher than those for the C(sp3) atoms to which
they were connected; the methyl groups were refined
with the torsion angle as a free variable. The hydride
atoms of compounds 3, 6, and 8 were isotropically
refined. All non-hydrogen atoms were anisotropically
refined, and weighting schemes were used in the last
cycles of refinement. Weights are calculated from the
following formula: w ) 1/[σ2(Fo2) + (aP)2 + bP], where
P ) (Fo + 2Fc )/3. Compound 2 crystallizes in an
orthorhombic system with the centrosymmetric space
group Pbcn and is organized around an inversion center.
Consequently, the nitrogen and the C(1) atoms are
statistically distributed on both sides of the inversion
center, giving rise to a pseudo-centrosymmetry. As a
result, it was impossible to locate the hydride atoms in
2. Drawings of the molecules were performed by using
the program ORTEP320 with 50% probability displace-
ment ellipsoids for non-hydrogen atoms.
Com p u ta tion a l Deta ils. All the calculations were
performed at the DFT level (B3PW91)21 with the
Gaussian 98 set of programs.22 Ru and P atoms were
represented with relativistic effective core pseudo-
potentials (RECP) of the Stuttgart group23 and the
associated basis set augmented with a polarization
1
) 6.3 Hz, H2), 7.60 (t, 1H, J HH ) 7.6 Hz, H3), 7.68 (m,
1
1H, H7), 7.84 (m, 1H, H4), 7.88 (d, 1H, J HH ) 8.2 Hz,
1
H10), 9.37 (d, 1H, J HH ) 5.4 Hz, H1). 31P{1H} NMR
(201.46 MHz, THF-d8, 293 K; δ): 51.72 ppm. 13C{1H}
NMR (125.70 MHz, THF-d8, 293 K; δ): 19.6 (s,
P(CHMe2)3), 20.1 (s, CHMe2)3), 27.9 (t, J PC ) 9.8 Hz,
P(CHMe2)3), 119.4 (s, C4), 120.5 (s, C8), 121.5 (s, C2),
123.8 (s, C7), 127.3 (s, C9), 135.1 (s, C3), 144.4 (s, C10),
147.2 (s, C6), 155.7 (s, C1), 167.5 (s, C5), 191.4 (t, J PC
13.4 Hz, C11), 207.3 (t, J PC ) 12.8 Hz, CO).
Ru H(C2H4)(p h -p y)(P iP r 3)2 (8). C2H4 was bubbled
through a pentane solution (20 mL) of 2 (150 mg, 0.25
mmol) for 5 min. The resulting red solution was filtered
and transferred into a Fisher-Porter bottle. It was
stored under 3 bar of C2H4 at -20 °C overnight. The
resulting orange crystals were stored under 3 bar of
C2H4. A suitable NMR sample can be obtained under
800 mbar of C2H4. Yield: ca. 65%. Anal. Calcd for
C31H55NP2Ru: C, 61.56; H, 9.17; N, 2.32. Found C,
1
60.93; H, 8.96; N, 2.16. H NMR (500.13 MHz, THF-d8,
2
293 K; δ): -10.87 (t, J PH ) 24.8 Hz, 1H, RuH), 0.74
(m, 18H, P(CHMe2)3), 1.05 (m, 18H, P(CHMe2)3), 1.63
(m, 6H, P(CHMe2)3), 2.51 (br, 4H, η2-C2H4), 6.70 (m, 2H,
1
H8/H9), 7.00 (t, 1H, J HH ) 6.5 Hz, H2), 7.57 (t, 1H,
2
2
1
1J HH ) 7.6 Hz, H3), 7.72 (m, 1H, H7), 7.93 (d, 1H, J HH
1
) 8.3 Hz, H4), 8.34 (d, 1H, J HH ) 6.9 Hz, H10), 9.84
1
(d, 1H, J HH ) 5.7 Hz, H1); uncoordinated C2H4 is
observed at 5.35 ppm. 31P{1H} NMR (201.46 MHz, THF-
d8, 293 K; δ): 37.18 ppm. 13C{1H} NMR (125.70 MHz,
THF-d8, 293 K; δ): 20.2 (s, P(CHMe2)3), 21.0 (s, CHMe2)3),
25.4 (partially hidden by THF signal, P(CHMe2)3), 47.0
(s, η2-C2H4), 118.9 (s, C4), 119.4 (s, C8), 120.5 (s, C2),
124.5 (s, C7), 126.4 (s, C9), 134.7 (s, C3), 145.1 (s, C6),
147.0 (s, C10), 155.5 (s, C1), 169.6 (s, C5), 199.3 (t, J PC
) 12.0 Hz, C11); uncoordinated C2H4 is observed at
123.3 ppm.
Ru H(THF )(p h -p y)(P iP r 3)2 (9). A solution of 300 mg
(0.51 mmol) of 2 in THF was heated to reflux for 3 h
inside a Schlenk bulb equipped with a Young tap to
avoid grease contamination. During the reaction a slight
Ar stream was passed over the solution from time to
time. The deep red reaction mixture was cooled to room
temperature, and the THF was removed in vacuo. The
resulting deep red solid was dried at 10-6 mbar for 1 h.
1H NMR (500.13 MHz, THF-d8, 293 K; δ): -10.95 (t,
J PH ) 26.4 Hz, 1H, RuH), 0.77 (m, 18H, P(CHMe2)3),
0.95 (m, 18H, P(CHMe2)3), 2.06 (m, 6H, P(CHMe2)3),
(16) Sheldrick, G. M. SHELX-97 and SADABS Programs for Crystal
Structure Analysis (Release 97-2); University of Go¨ttingen, Go¨ttingen,
Germany, 1998.
(17) Altomare, A.; Cascarano, G.; Giacovazzo C.; Guagliardi, A.
SIR92-A Program for Crystal Structure Solution. J . Appl. Crystallogr.
1993, 26, 343.
(18) Farrugia, L. J . WINGX. J . Appl. Crystallogr. 1999, 32, 837.
(19) International Tables for X-ray Crystallography; Kynoch
Press: Birmingham, England, 1974; Vol. IV.
(20) Farrugia, L. J . ORTEP3 for Windows. J . Appl. Crystallogr.
1997, 30, 565.
1
6.38 (m, 2H, H6 and H7), 6.96 (t, 1H, J HH ) 6.4 Hz,
(21) (a) Becke, A. D. J . Chem. Phys. 1993, 98, 5648. (b) Perdew, J .
P.; Wang, Y. Phys. Rev. B 1992, 82, 284.
H2), 7.33 (m, 1H, H4), 7.37 (m, 1H, H7), 7.50 (t, 1H,
1
1J HH ) 7.6 Hz, H3), 7.82 (d, 1H, J HH ) 8.3 Hz, H10),
(22) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.;
Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.; Daniels,
A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .; Barone, V.;
Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford,
S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma,
K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J . B.;
Cioslowski, J .; Ortiz, J . V.; Stefanov, B. B.; Liu, G.; Liashenko, A.;
Piskorz, P.; Komaromi, I.; Gomperts, G.; Martin, R. L.; Fox, D. J .; Keith,
T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Gonzalez, C.;
Challacombe, M.; Gill, P. M. W., J ohnson, B. G.; Chen, W.; Wong, M.
W.; Andres, J . L.; Head-Gordon, M.; Replogle, E. S.; Pople, J . A.
Gaussian 98, Revision A.7; Gaussian Inc., Pittsburgh, PA, 1998.
(23) (a) Andrae, D.; Hau¨ssermann, U.; Dolg, M.; Stoll, H.; Preuss,
H. Theor. Chim. Acta 1990, 77, 123. (b) Bergner, A.; Dolg, M.; Ku¨chle,
W.; Stoll, H.; Preuss, H. Mol. Phys. 1999, 30, 1431.
1
9.28 (d, 1H, J HH ) 5.6 Hz, H1). 31P{1H} NMR (201.46
MHz, THF-d8, 293 K, δ): 54.05 ppm. 13C{1H} NMR
(125.70 MHz, THF-d8, 293 K; δ): 19.4 (s, P(CHMe2)3),
20.0 (s, CHMe2)3), 26.2 (t, J PC ) 9.8 Hz, P(CHMe2)3),
116.0 (s, C4), 118.6 (s, C8), 119.4 (s, C2), 123.3 (s, C7),
125.3 (s, C9), 132.1 (s, C3), 143.6 (s, C10), 143.7 (s, C6),
152.6 (s, C1), 166.0 (s, C5), 185.0 (t, J PC ) 11.6 Hz, C11).
X-r a y An a lysis. Data were collected at low temper-
ature (T ) 150 K for 2, 113 K for 3, 180 K for 6, and
183 K for 8) on a Stoe imaging plate diffraction system
(IPDS) for 2, 3, and 6 and on a Bruker XPS diffraction

Ortho-Metalated Ru Hydrido Dihydrogen Complexes
Organometallics, Vol. 23, No. 6, 2004 1433
function (R ) 1.235 for f on Ru and R ) 0.387 for d on
P). The atoms directly bonded to Ru (C, N, hydrides,
and the ligands N2, CO, C2H4, and O2) were treated with
6-31G(d,p) basis sets, while the remaining atoms were
represented with 6-31G basis sets. All the geometries
were optimized without any symmetry constraint, and
the natures of the extrema (minima or transition states)
were checked by analytical computation of the Hessian
matrixes. Unless otherwise stated, the energies given
are electronic energies without any ZPE correction, as
inclusion of the latter did not bring any significant
alteration of the results.
Fonds der Chemischen Industrie, the (DFH/UFA) Rob-
ert Bosch Stiftung, the University Montpellier 2, and
the CNRS of France. We also thank the EU through
the HCM program, Hydrogen Location and Transfer
network.
Su p p or tin g In for m a tion Ava ila ble: Tables giving X-ray
structural data for 2, 3, 6, and 8. This material is available
free of charge via the Internet at http://pubs.acs.org. CCDC
229177-229180 contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, by emailing data_re-
quest@ccdc.cam.ac.uk, or by contacting The Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, U.K. (fax +44 1223 336033).
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft, Bonn, Germany, the
OM034259C