Complexes of bis-ortho-cyclometalated bisphosphinoaryl ruthenium(II) cations with neutral meta-bisphosphinoarene ligands containing an agostic C-H...Ru interaction

Article abstract of DOI:10.1021/om0005001

The synthesis, characterization, and reactivity of various ruthenium(II) complexes [Ru-(R-PCP)(R′-PCHP)][OTf] are presented. These complexes are highly dissymmetric and show fluxional behavior in solution. They contain one monoanionic, η³-P,C,P′-tridentate-bonded bisphosphinoaryl ligand (R-PCP = [C₆H₂(CH₂PPh₂)₂-2,6-R-4]^-; R = H or Br) and one neutral, trans-P,P′-bidentate-bonded bisphosphinoarene ligand (R′-PCHP = C₆H₃(CH₂PPh₂)₂-3,5-R′-1). The C-H bond that is ortho to both CH₂PPh₂ substituents of the bidentate-bonded ligand is interacting with the metal center (i.e., has an agostic contact with the cationic ruthenium center). The location of the agostic proton in the ¹H NMR spectrum as well as the three-dimensional structure of these complexes in solution was obtained by means of several two-dimensional NMR techniques (¹H-¹H COSY, ³¹P-¹H COSY, ¹³C-¹H COSY, ¹H NOESY, ¹H ROESY, and ³¹P EXSY). The ¹J_HC of the agostic contact amounted to 112 Hz, which represents a reduction of 46 Hz in relation with the same coupling for this C-H bond in the free ligand. Furthermore, the molecular geometry of [Ru(H-PCP)(PCHP)][OTf] in the solid state was established by single-crystal X-ray diffraction techniques, and the structural features corroborate with the observations in solution. In the complex [Ru(H-PCP)(Br-PCHP)][OTf], interconversion of the cyclometalated and neutral bisphosphine ligands via exchange of the agostic hydrogen atom from the neutral to the cyclometalated carbon to yield [Ru(Br-PCP)(H-PCHP)][OTf] was observed. A mechanistic proposal based on an aromatic electrophilic substitution is discussed. Moreover, the reaction of [Ru(OSO₂-CF₃)(NCN)(PPh₃)] (NCN = [C₆H₃(CH₂NMe₂)₂-2,6]^-) with the neutral bisphosphinoarene resulted in the quantitative formation of the new cyclometalated species [Ru(R-PCP)(R-PCHP)][OTf] with the net loss of the neutral bisaminoarene ligand NCHN and PPh₃.

Full text of DOI:10.1021/om0005001

Organometallics 2000, 19, 5287-5296
5287
Com p lexes of Bis-or th o-cyclom eta la ted Bisp h osp h in oa r yl
Ru th en iu m (II) Ca tion s w ith Neu tr a l
Meta -bisp h osp h in oa r en e Liga n d s Con ta in in g a n Agostic
C-H‚‚‚Ru In ter a ction †
Paulo Dani, Mieke A. M. Toorneman, Gerard P. M. van Klink, and
Gerard van Koten*
Department of Metal-Mediated Synthesis, Debye Institute, Utrecht University,
Padualaan 8, 3584 CH Utrecht, The Netherlands
Received J une 7, 2000
The synthesis, characterization, and reactivity of various ruthenium(II) complexes [Ru-
(R-PCP)(R′-PCHP)][OTf] are presented. These complexes are highly dissymmetric and show
fluxional behavior in solution. They contain one monoanionic, η3-P,C,P′-tridentate-bonded
bisphosphinoaryl ligand (R-PCP ) [C6H2(CH2PPh2)2-2,6-R-4]-; R ) H or Br) and one neutral,
trans-P,P′-bidentate-bonded bisphosphinoarene ligand (R′-PCHP ) C6H3(CH2PPh2)2-3,5-
R′-1). The C-H bond that is ortho to both CH2PPh2 substituents of the bidentate-bonded
ligand is interacting with the metal center (i.e., has an agostic contact with the cationic
1
ruthenium center). The location of the agostic proton in the H NMR spectrum as well as
the three-dimensional structure of these complexes in solution was obtained by means of
1
several two-dimensional NMR techniques (1H-1H COSY, 31P-1H COSY, 13C-1H COSY, H
1
1
NOESY, H ROESY, and 31P EXSY). The J HC of the agostic contact amounted to 112 Hz,
which represents a reduction of 46 Hz in relation with the same coupling for this C-H bond
in the free ligand. Furthermore, the molecular geometry of [Ru(H-PCP)(PCHP)][OTf] in
the solid state was established by single-crystal X-ray diffraction techniques, and the
structural features corroborate with the observations in solution. In the complex [Ru(H-
PCP)(Br-PCHP)][OTf], interconversion of the cyclometalated and neutral bisphosphine
ligands via exchange of the agostic hydrogen atom from the neutral to the cyclometalated
carbon to yield [Ru(Br-PCP)(H-PCHP)][OTf] was observed. A mechanistic proposal based
on an aromatic electrophilic substitution is discussed. Moreover, the reaction of [Ru(OSO2-
CF3)(NCN)(PPh3)] (NCN ) [C6H3(CH2NMe2)2-2,6]-) with the neutral bisphosphinoarene
resulted in the quantitative formation of the new cyclometalated species [Ru(R-PCP)(R-
PCHP)][OTf] with the net loss of the neutral bisaminoarene ligand NCHN and PPh3.
In tr od u ction
been claimed to have unequivocally established the
involvement of such species in the process of C-M bond
formation.1,5,8,13,19 The participation of such intermedi-
ates is considered feasible for the following reasons: (i)
chelation of a polydentate ligand is known to be ther-
modynamically favored over open-chain structures; (ii)
chelation brings the carbon atom to be metalated in
close proximity of the metal center; (iii) the metalated
carbon atom is generally situated in that part of the
The cyclometalation of bidentate ligands is thought
to involve η2-E,E′ species (E ) N, P, As, S) as crucial
intermediates,1-18 and there are situations where it has
* To whom correspondence should be addressed. E-mail:
g.vankoten@chem.uu.nl. Fax: +(31) 30 2523615.
† Dedicated to Professor Dr. H. Gu¨nther (Universita¨t-Gesamthoch-
schule Siegen, Siegen, Germany) on the occasion of his 65th birthday.
(1) Bennett, M. A.; J ohnson, R. N.; Tomkins, I. B. J . Organomet.
Chem. 1977, 128, 73-84.
(10) Gozin, M.; Aizenberg, M.; Liou, S.-Y.; Welsman, A.; Ben-David,
Y.; Milstein, D. Nature 1994, 370, 42-44.
(2) Crocker, C.; Errington, R. J .; Markham, R.; Moulton, C. J .; Shaw,
B. L. J . Chem. Soc., Dalton Trans. 1982, 387-395.
(3) Cross, R. J .; Kennedy, A. R.; Manojlovic-Muir, L.; Muir, K. W.
J . Organomet. Chem. 1995, 493, 243-249.
(11) Liou, S.-Y.; Gozin, M.; Milstein, D. J . Chem. Soc., Chem.
Commun. 1995, 1965-1966.
(12) van der Boom, M. E.; Kraatz, H.-B.; Ben-David, Y.; Milstein,
D. Chem. Commun. 1996, 2167-2168.
(4) Rimml, H.; Venanzi, L. M. J . Organomet. Chem. 1983, 259, C6-
C7.
(13) Rybtchinski, B.; Vigalok, A.; Ben-David, Y.; Milstein, D. J . Am.
Chem. Soc. 1996, 118, 12406-12415.
(5) Karlen, T.; Dani, P.; Grove, D. M.; Steenwinkel, P.; van Koten,
G. Organometallics 1996, 15, 5687-5694.
(6) Ogasawara, M.; Saburi, M. Organometallics 1994, 13, 1911-
(14) Gandelman, M.; Vigalok, A.; Shimon, L. J . W.; Milstein, D.
Organometallics 1997, 16, 3981-3986.
1917.
(15) Rybtchinski, B.; Ben-David, Y.; Milstein, D. Organometallics
1997, 16, 3786-3793.
(7) Steenwinkel, P.; Kolmschot, S.; Gossage, R. A.; Dani, P.; Veld-
man, N.; Spek, A. L.; van Koten, G. Eur. J . Inorg. Chem. 1998, 477-
483.
(8) Lesueur, W.; Solari, E.; Floriani, C.; Chiesi-Villa, A.; Rizzoli, C.
Inorg. Chem. 1997, 36, 3354-3362.
(9) Gozin, M.; Welsman, A.; Ben-David, Y.; Milstein, D. Nature 1993,
364, 699-701.
(16) van der Boom, M. E.; Liou, S.-Y.; Ben-David, Y.; Gozin, M.;
Milstein, D. J . Am. Chem. Soc. 1998, 120, 13415-13421.
(17) van der Boom, M. E.; Liou, S.-Y.; Ben-David, Y.; Shimon, L. J .
W.; Milstein, D. J . Am. Chem. Soc. 1998, 120, 6531-6541.
(18) Rybtchinski, B.; Milstein, D. Angew. Chem., Int. Ed. 1999, 38,
870-883.
10.1021/om0005001 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 11/05/2000

5288 Organometallics, Vol. 19, No. 25, 2000
Sch em e 1. Syn th esis of Ru th en iu m Tr ifla te Com p lexes
Dani et al.
ligand skeleton that is located between both donor
heteroatoms; and finally (iv) cyclometalation of the
ligand is generally a highly stereoselective process.
Here, we report the results of our investigations
involving the aryl ligands C6H3(CH2PPh2)2-3,5-R-1, ab-
breviated as R-PCHP (1, R ) H; 2, R ) Br), and the
ruthenium-triflate complexes [Ru(OTf)(C6H3{CH2E}2-
2,6)(PPh3)] (4, E ) PPh2; 7, E ) NMe2; OTf ) CF3SO3-).
In addition, a unique example of a cationic complex, [Ru-
(H-PCP)(PCHP)][OTf], was isolated containing both an
η3-P,C,P′ tridentate-bonded PCP monoanion and a
trans-η2-P,P′ bidentate-bonded PCHP ligand. The η2-
P,P′ ligand has one aromatic C-H bond coordinated to
the metal center (i.e., has an agostic C-H-to-Ru con-
tact).20 Cross-experiments involving two different bis-
phosphine ligands coordinated to the ruthenium cationic
center suggest that agostic and metalated sites can
exchange positions. A mechanism based on an aromatic
electrophilic pathway is proposed for this process.
at ca. 29 ppm is found, which points to the presence of
a byproduct. Interestingly, when the reaction solution
was layered with benzene, a brown solid slowly precipi-
tated, causing concomitant disappearance of the singlet
detected in the 31P NMR spectrum. The 1H NMR
spectrum of the brown solid in CD2Cl2 consisted of broad
resonances which remained unaffected by temperature
variation in the range -100 to +25 °C, suggesting that
the peak broadness was not caused by exchange (flux-
ional) processes but more likely by the presence of
paramagnetic RuIII species. The formation of this kind
of oxidation product is often observed in halide abstrac-
tion reactions of electron-rich (i.e., late transition) metal
complexes with silver salts. This occurs as a result of
metal oxidation via an electron-transfer process, ulti-
mately forming metallic (elemental) silver as a byprod-
uct. An even more drastic situation was observed in the
case of the analogous compounds [RuCl(NCN)(PPh3)] (5,
NCN ) [C6H3(CH2NMe2)2-2,6]-) and [Ru(NCN)(terpy)]-
Cl (6). Due to the σ-donating character of the dimeth-
ylamino groups, the ruthenium(II) center in these
complexes is more prone to oxidation. Attempts to
replace the chloride ligand in 5 by typical noncoordi-
Resu lts a n d Discu ssion
Syn th esis of Ru th en iu m Tr ifla te Com p lexes. The
formation of [RuCl(R-PCP)(PPh3)] (R-PCP ) [C6H2-
(CH2PPh2)2-2,6-R-4]-, R ) H,5,21 Ph,5 Br;22 see Scheme
1 for R ) H (3)) complexes obtained from the reaction
of [RuCl2(PPh3)3] with the parent arene R-PCHP
proceeds with net loss of HCl. The best results were
obtained with 1,2-dichloroethane as solvent in terms of
reaction time, yields, and the ease of workup of the
resulting products.22 In the case of [RuCl(PCP)(PPh3)]
(3, R-PCP with R ) H, further abbreviated as PCP),
replacement of the remaining chloride is achieved by
reaction with AgOTf, thus forming 4 in 53% yield.5 The
reason for such moderate yield can be deduced from the
resonances observed in the 31P NMR spectrum of the
crude reaction mixture. In this spectrum in addition to
a doublet and a triplet related to 4, also a broad singlet
-
nating anions (e.g., BF4 or OTf -) using the corre-
sponding silver salt were not successful and resulted
in complete decomposition of the starting materials. In
case of 6 (and related complexes involving other types
of NCN ligands), a selective oxidative reaction is ob-
served leading to oxidation of both the metal center (RuII
to RuIII) and the ligand framework.23-25 The latter
oxidation results in the formation of a new C-C bond,
i.e., yielding ionic 4,4′-biphenylene-bridged bis-ruthe-
nium complexes [Ru2(4,4′-(C6H2{CH2NMe2}2-2,6)2)-
(terpy)2]n+ (n ) 2, RuII,RuII; and 4, RuIII,RuIII).
In contrast with the nonselective reactions with AgX,
complexes 3 and 5 react selectively with a 3-fold excess
of Me3SiOTf 26 at room temperature (RT) to yield the
corresponding triflate complexes 4 and 7, respectively
(19) Baltensperger, U.; Gunter, J . R.; Ka¨gi, S.; Kahr, G.; Marty, W.
Organometallics 1983, 2, 571-578.
(23) Sutter, J .-P.; Grove, D. M.; Beley, M.; Collin, J . P.; Veldman,
N.; Spek, A. L.; Sauvage, J . P.; van Koten, G. Angew. Chem., Int. Ed.
Engl. 1994, 33, 1282-1285.
(20) (a) Brookhart, M.; Green, M. L. H.; Wong, L.-L. Prog. Inorg.
Chem. 1988, 36, 1-124. (b) Crabtree, R. H.; Hamilton, D. G. Adv.
Organomet. Chem. 1988, 28, 299-338.
(24) Beley, M.; Collin, J .-P.; Louis, R.; Metz, B.; Sauvage, J .-P. J .
Am. Chem. Soc. 1991, 113, 8521-8522.
(21) J ia, G.; Lee, H. M.; Williams, I. D. J . Organomet. Chem. 1997,
534, 173-180.
(22) Dani, P.; Richter, B.; van Klink, G. P. M.; van Koten, G. Eur.
J . Inorg. Chem., in press.
(25) Beley, M.; Collin, J .-P.; Sauvage, J .-P. Inorg. Chem. 1993, 32,
4539-4543.
(26) Aizenberg, M.; Milstein, D. J . Chem. Soc., Chem. Commun.
1994, 411.

Complexes of Bisphosphinoaryl Ru(II) Cations
Organometallics, Vol. 19, No. 25, 2000 5289
Sch em e 2. Syn th esis of Ru Com p lexes Con ta in in g
a n Agostic Con ta ct
F igu r e 1. 31P{1H} NMR spectra of [Ru(PCP)(PCHP)][OTf]
(8) in CD2Cl2 at several temperatures.
(see Scheme 1). The only other products in the reaction
are Me3SiCl (a volatile liquid) and residual Me3SiOTf
(highly soluble in apolar solvents). Both of these latter
materials can be easily removed.
The structure in solution of [Ru(OTf)(C6H3{CH2-
NMe2}2-2,6)(PPh3)] (7) was established by its distinct
1H and 31P NMR spectra as well as by its reactivity
toward the PCHP ligand (see below). Interestingly,
complex 7 is stable for long periods (2 months) as a
solution in benzene. However, in the solid state 7 slowly
decomposes within one week to a brown benzene-
insoluble solid.
Reaction of Ru th en iu m -Tr iflate Com plexes with
R -P CH P Liga n d s. Reaction of a solution of 4 in
CH2Cl2 with ligand 1 in a 1:1 molar ratio (see Scheme
2) at room temperature resulted in a rapid color change
of the reaction solution from green to dark yellow. The
31P{1H} NMR spectrum of this solution (RT) showed
very broad signals between 15 and 45 ppm as well as a
signal at ca. -4.5 ppm. This latter signal points to the
presence of free PPh3. Workup of the reaction mixture
led to the isolation of a yellow solid. The 19F{1H} NMR
spectrum (RT) showed one singlet resonance located at
-73.41 ppm, indicating the presence of a noncoordi-
nated triflate group.27
F igu r e 2. (a) 31P NMR spectrum in CD2Cl2 of [Ru(PCP)-
(PCHP)][OTf] (8) at -70 °C. (b) Simulated spectrum
assuming an ABMN spin system.30
the presence of four magnetically and chemically non-
equivalent phosphorus atoms (arbitrarily labeled PA, PB,
PC, and PD), whose spectral distribution, chemical shift,
and coupling constants are shown in Figure 2. Com-
parison of the calculated coupling constants reveals that
PA is trans to PB, while PC is trans to PD. This
conclusion, in combination with the fact that PCP type
ligands are able to adopt a trans-spanning P,P′-
coordination mode around a metal center, led to the
proposal that a complex containing one trans-P,P′-
chelated bisphosphinoarene and one cyclometalated
bisphosphinoaryl ligand (see 8 in Scheme 2) was formed.
Strong supporting evidence for this proposal came from
a single-crystal X-ray structure determination of 8,
which was published in a preliminary communication.28
Single crystals of [Ru(C6H3{CH2PPh2}2-2,6)(C6H4{CH2-
PPh2}2-1,3)][OTf], 8, were obtained from a solution in
A reversible, temperature-dependent behavior of the
1H and 31P NMR resonance patterns was observed
(Figure 1). In the slow exchange limit (below -70 °C),
a complicated 31P NMR spectrum was obtained. Inter-
estingly, a two-dimensional 31P-31P COSY NMR spec-
trum at -70 °C has shown the presence of cross-peaks
between all multiplets, indicating they are related to
only one compound and not to a mixture of two or more
different complexes.
Integration and simulation of the one-dimensional 31
P
NMR spectrum observed at -70 °C strongly suggested
(27) van Stein, G. C.; van Koten, G.; Vrieze, K.; Brevard, C.; Spek,
A. L. J . Am. Chem. Soc. 1984, 106, 4486-4492.
(28) Dani, P.; Karlen, T.; Gossage, R. A.; Smeets, W. J . J .; Spek, A.
L.; van Koten, G. J . Am. Chem. Soc. 1997, 119, 11317-11318.

5290 Organometallics, Vol. 19, No. 25, 2000
Dani et al.
F igu r e 3. Stereoview of the crystal structure of the [Ru(PCP)(PCHP)] cation of 8. Hydrogen atoms from phenyl groups
were omitted for clarity.
F igu r e 4. Positioning of the aromatic groups in the [Ru(PCP)(PCHP)] cation of 8. In views a and b the orientation of the
various phosphorus atoms are retained. Protons (except Ha) were omitted for clarity. (a) View of the neutral PCHP ligand.
(b) View of the cyclometalated PCP ligand. (c) Positioning of Ha of PCHP in relation to the ruthenium center and to the
PCP xylylene ring.
dichloromethane layered with a toluene/ether mixture.
The molecular structure consists of a bis-ortho-phos-
phinoaryl and a meta-bisphosphinoarene ligand bound
to one ruthenium atom (Figure 3), as suggested by the
solution NMR data. The bisphosphinoaryl ligand is η3-
P,C,P′-tridentate-bonded to the Ru-center, while the
meta-bisphosphinoarene ligand is P,P′-bidentate coor-
dinated. The local symmetry around the ruthenium
center is best described as a highly distorted octahedral
environment, lacking any kind of symmetry element
(hence, C1 point group symmetry). The location of the
hydrogen on C11 (Ha) of the trans-η2-P,P′-bonded bis-
phosphinoarene ligand was clearly refined on the final
difference map. The C11-Ha distance is 1.15 Å, which
is significantly longer than a normal C-H (aromatic)
bond distance. Moreover, the calculated Ru‚‚‚H distance
is 1.76 Å, which is close to the Ru-H bond distance in
a classical ruthenium hydride,29 suggesting a strong
Ru-Ha interaction in 8. Atom Ha is ca. 30° out of the
plane of the PCHP xylylene group, while the C11-Ha
bond makes an angle of ca. 109° with the ruthenium
center (Figure 4c). The carbon atoms of the neutral
PCHP-xylylene ring are coplanar (see Figure 4a),
indicating no loss of aromaticity, as would be expected
in the case of a C11 sp2fsp3 rehybridization resulting
from Ru-C11 σ-bonding. As can be seen in Figure 4a,b,
the meta-xylylene rings are not orthogonal to each other.
In the neutral PCHP ligand, this part of the molecule
is bent toward P12 (Figure 4a). The Ru-P bonds are
slightly longer than those in the ruthenium-PCP
complex 3,21 especially the Ru-P21 bond (2.4432 Å) of
the neutral bisphosphinoarene ligand (see Figure 6 for
selected bond distances and angles).
It is interesting to note that an alternative way to 8
involves the reaction of 1 with 7 in benzene-d6. This
reaction resulted in complete replacement of all coor-
dinated ligands in 7 by the bisphosphinoarene ligand;
that is, the cyclometalated NCN ligand becomes proto-
nated, an η3-P,C,P′-bonded bisphosphinoaryl ligand
results, and the metal-bound triflate becomes merely a
counterion (see Scheme 2). This was confirmed by
(29) Guggenberger, L. J . Inorg. Chem. 1973, 12, 1317-1322, and
references therein.

Complexes of Bisphosphinoaryl Ru(II) Cations
Organometallics, Vol. 19, No. 25, 2000 5291
F igu r e 5. 31P-1H COSY NMR spectrum of [Ru(PCP)(PCHP)][OTf] (8) in CD2Cl2 at -70 °C.
(vide infra) and thus can act as a reactive source of
ruthenium(II).
Rea ctivity of 8 w ith Ba ses a n d w ith Ch lor id e
Sou r ces. Attempts to promote abstraction of Ha in 8
by reaction with either bases33 or an acid20 (HCl), to
force the formation of a second C-Ru bond, were not
successful (see Scheme 3). This is already evident from
the reaction depicted in Scheme 2, in which starting
from the Ru-NCN complex 7, 8 is formed at the expense
of the displacement of the bisaminoarene ligand 10, i.e.,
of an organic base. Moreover, CD2Cl2 solutions of 8 in
sealed NMR tubes containing stronger amine bases, e.g.,
triethylamine and “proton sponge”, did not result in any
reaction even after two months when kept at temper-
atures around -20 °C. However, after 4 days at room
temperature, the 31P NMR spectrum (RT) of these
samples revealed the disappearance of the broad signals
related to the starting material and the presence of a
new set of resonances. These new patterns strongly
suggested the formation of the already known complexes
11 (d/t at 41.48/83.74 ppm) and 12 (d/t 42.06/83.74 ppm
and a singlet at -10.25 ppm, the latter due to the free
diphenylphosphino group; see Scheme 3).22 A broad
singlet at 29.76 was also detected in the same spectrum.
The material responsible for this singlet was isolated
as a brown solid insoluble in benzene. Most likely, the
nature of this material is identical with the paramag-
netic impurity observed during the synthesis of 4 with
AgOTf (see above). Likewise, the 1H and 31P NMR
spectra were temperature independent and contained
only broad resonances.
F igu r e 6. Assignments based on the various NMR data
realized for [Ru(PCP)(PCHP)][OTf] (8). For clarity, the [Ru-
(PCP)] and [Ru(PCHP)] fragments are plotted separately
(phenyl protons omitted). The ortho-position number 2 of
the assigned phenyl groups is indicated. Bond distances
(Å) and angles (deg.): Ru-P11 2.3732(9), Ru-P21 2.4432-
(9), Ru-P12 2.3716(9), Ru-P22 2.3575(9), Ru-C12 2.115-
(3), Ru-H 1.76(4), Ru‚‚‚C11 2.395(4), C11-H 1.15(4), P11-
Ru-P21 152.74(3), P12-Ru-P22 153.64(3), P11-Ru-P12
91.62(3), P11-Ru-P22 95.89(3), C11-Ru-C12 171.47(11),
Ru-H-C11 109(3).
comparison of the 1H and 31P NMR spectra of the
isolated solid with an authentic sample of 8. Moreover,
in the 31P NMR spectrum, free PPh3 was present, while
1
in the H NMR spectrum of the reaction mixture, free
NCHN was likewise detected. In conclusion, complex 7
is involved in a highly selective exchange reaction31,32
(30) Simulation performed using gNMR 3.6, Cherwell Scientific
Publishing Limited: Oxford, 1995.
(31) Dani, P.; Albrecht, M.; van Klink, G. P. M.; van Koten. G.
Organometallics 2000, 19, 4468-4476.
(32) Albrecht, M.; Dani, P.; Lutz, M.; Spek, A. L.; van Koten, G. J .
Am. Chem. Soc., in press.
(33) Vigalok, A.; Uzan, O.; Shimon, L. J . W.; Ben-David, Y.; Martin,
J . M. L.; Milstein, D. J . Am. Chem. Soc. 1998, 120, 12539-12544.

5292 Organometallics, Vol. 19, No. 25, 2000
Dani et al.
our first goal was to locate these protons in the 1H NMR
spectrum of 8.
Sch em e 3. Rea ctivity of 8 w ith Ba ses a n d w ith
Ch lor id e Sou r ces
Initially, the complexity of the one-dimensional 1H
NMR spectrum hampered the precise location of the
chemical shift of Ha. Interestingly, Ha is the only
hydrogen atom in 8 capable of showing reasonable
through-bond coupling with all four phosphorus atoms,
for it is only two bonds apart from each of them. A two-
dimensional 31P-1H COSY NMR spectrum was recorded
at -70 °C (Figure 5). Despite the apparent spectral
complexity of the NMR spectrum of 8, the location of
all the important protons (i.e., their chemical shift and
information on which type of phosphorus they are
related to) can be extracted (Figure 6). The aromatic
proton Ha is found at 1.23 ppm and shows cross-peaks
with the PA, PB, and PD phosphorus nuclei. Therefore,
Ha is unambiguously bonded to the Ru center. The
reasons for the nonpresence of a cross-peak between Ha
and PC were not further investigated. To substantiate
the agostic C-Ha‚‚‚Ru interaction, complex 8-D was
synthesized by reacting 4 with the deuterated H-PCDP
ligand 1-D (isotopic purity > 99%) in CH2Cl2 at room
temperature (Scheme 2). Indeed, the signal located at
1.23 ppm (1H NMR) was the one affected in the 1H NMR
spectrum of 8-D, confirming the findings of the 31P-1H
COSY NMR spectrum. However, it was observed that
a small proton resonance was still visible at 1.23 ppm,
indicating that the partial replacement of the deuterium
by hydrogen had occurred (less than 10% is estimated).
The 2H{1H} NMR spectrum (RT) showed a broad signal
centered at 1.23 ppm and a small one at 7.35 ppm. Due
Addition of a solution of HCl in water (ca. 0.2 M) to a
solution of 8 in CD3OD caused immediate precipitation
1
of a green solid. The H and 31P NMR spectra of this
material in C6D6 showed that exclusively 11 had been
formed (see Scheme 3). A similar result was obtained
upon addition of NH4Cl to a solution of 8 in dichlo-
romethane. In this case, addition of [RuCl2(PPh3)3] and
heating the reaction solution overnight yielded the
known compound 3 in virtually quantitative yield.
In conclusion, addition of bases or acid to complex 8
did not cause metalation of C11. Instead, phosphine
dissociation occurred. The steric demand involved in the
formation of four five-membered rings as well as the
electronic influence exerted by two trans anionic ipso-
carbons34,35 may be at the root of the observed behavior.
It should be noted that there are examples of ruthenium
complexes containing aromatic agostic C-H bonds that
do not show any reactivity toward bases or acids.36
Str u ctu r a l Ch a r a cter iza tion of 8 in Solu tion by
NMR Sp ectr oscop y. The low molecular symmetry
properties found in the solid-state structure of 8 is in
good agreement with the observed 31P{1H} NMR spec-
trum recorded in CD2Cl2 solution (Figure 2). A series
of two-dimensional NMR studies were carried out at the
slow exchange limit temperatures (-70 to -90 °C) to
further our understanding of the nature of the interac-
tion between Ha and the ruthenium center. An ad-
ditional objective was to probe the possible fluxional
behavior of 8. It is important to note that the most
informative proton nuclei, i.e., those that provide the
most useful structural information, are those that are
in close proximity to the ruthenium metal center, i.e.,
Ha, the phenyl ortho and benzylic protons. Therefore,
2
to the broadness of the H NMR spectrum, it is difficult
to assign the latter proton with certainty. However, the
deuterium scrambling occurred in a very selective
manner and is probably caused by an intramolecular
process.
Figure 5 also reveals that each of the diastereotopic
benzylic protons appears at distinct chemical shift
values. They were arbitrarily labeled after the name of
the respective phosphorus nuclei (Bn-A, -A*; Bn-B, -B*;
Bn-C, -C*; Bn-D, -D*). The symbol * was used to denote
benzylic (and phenyl) protons related to the same
phosphorus atom having a diastereotopic relationship
(see inset of Figure 5).
The cross-peaks related to the aromatic region (5-8
1
ppm) of the H NMR spectrum (Figure 5) are all due to
couplings with phenyl ortho protons. Different chemical
shifts are expected for ortho protons situated at different
phenyl groups, even if the phenyl groups are bonded to
the same phosphorus atom, because, as is the case of
the benzylic protons, the phenyl groups can be divided
into diastereotopic pairs (see Figure 4a,b). However, as
can be seen in Figure 5, PA, PB, and PD have four cross-
peaks in the aromatic region of the 1H NMR spec-
trum, indicating nonequivalence between ortho protons
related to the same phenyl ring. In the case of PC, where
there is only one cross-peak, most likely the situation
is the same as with PA, PB, and PD, and coincidence is
causing the chemical shift equivalence among all ortho
protons.
(34) Steffey, B. D.; Miedaner, A.; Maciejewski-Farmer, M. L.;
Bernatis, P. R.; Herring, A. M.; Allured, V. S.; Carperos, V.; DuBois,
D. L. Organometallics 1994, 13, 4844-4855.
1H-1H COSY and 1H-1H TOCSY NMR spectra
confirmed the assignments related to the benzylic
protons of 8. Furthermore, these spectra made clear
which ortho protons pertained to a specific phenyl ring
(35) Pape, A.; Lutz, M.; Mu¨ller, G. Angew. Chem., Int. Ed. Engl.
1994, 33, 2281-2284.
(36) Perera, S. D.; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1995,
3861-3866.

Complexes of Bisphosphinoaryl Ru(II) Cations
Organometallics, Vol. 19, No. 25, 2000 5293
Ta ble 1. 1H NMR Ch em ica l Sh ift a n d Assign m en ts
of [Ru (P CP )(P CHP )][OTf] (8)a
These measurements showed that Ha lacks any
chemical exchange cross-peak at temperatures lower
that -70 °C, while this proton does show NOE cross-
peaks with A, A*, B, and B* benzylic protons. This latter
observation is in concert with the 1H-1H COSY and
TOCSY analysis, which indicated that A and B type
protons are related to the P,P′-coordinated PCHP ligand.
Except for the benzylic proton A*, all other cross-peaks
between Ha and benzylic protons were relatively weak.
This parallels the observation that in the crystal
structure of 8 all distances between Ha and the respec-
tive benzylic protons of the PCHP ligand fall in a narrow
range (3.46-3.53 Å) except for the much shorter dis-
tance (2.64 Å) of the proton connected to benzylic carbon
C81. Consequently, this proton was assigned as A*.
Following similar procedures, the identity of most of the
aromatic ring carbons and protons could be established
(Figure 6).
phenyl protons
benzylic
o-H
o*-H
m-H
m*-H
p-H
proton
A
A*
B
B*
C
C*
D
5.78
6.24
5.15
6.65
6.53
6.68
7.08
7.39
7.13
6.53
6.35
7.03
6.13
7.33
a)
6.68
6.78
b
6.85
b
2.95
3.86
2.52
3.71
2.84
3.35
3.31
3.67
7.36-7.46
7.05
a)
a)
b
5.34
6.50
7.10
7.79
6.24
6.50
6.88-7.10
7.57
6.88
7.20
D*
H-3n
H-4n
H-5n
Ha
PCHP (n ) 1)
PCP (n ) 2)
7.33
6.92
7.75
b
7.33
7.12
1.22
a
b
For the labeling scheme; see Figure 6. It was not possible to
locate this proton with certainty in the 1H NMR spectrum with
the available data.
1
Whereas the H ROESY spectrum between -70 and
and the chemical shift of the protons H-31, H-41, and
H-51 (for the numbering, see Scheme 2). Interestingly,
H-31 and H-51 showed cross-peaks with benzylic pro-
tons A, B, and B*. Consequently, PA and PB (and the
associated benzylic and phenyl ortho protons) are re-
lated to the P,P′ (chelate)-bonded PCHP ligand, while
PC and PD belong to the cyclometalated PCP-anionic
fragment. These findings are summarized in the 1H
NMR spectrum of Figure 5 and in Table 1.
The nature of the C11-Ha interaction followed from
the results of a 13C-1H COSY NMR spectrum of 8 at
-70 °C. This experiment revealed a cross-peak involving
Ha and C11 (δC ) 118 ppm). The C11 chemical shift is
about 12 ppm to higher field in comparison with this
resonance in the parent PCHP ligand. In conclusion,
31P-1H and 13C-1H COSY established that Ha interacts
with both Ru and C11. These characteristics are typical
for agostic systems and explain the reduced magnitude
of the C-H coupling constant. Gated decoupling experi-
ments37 revealed that the actual value is 112 Hz, which
is 46 Hz smaller than this coupling constant in free
PCHP. The observed ∆J is in the normal range for
complexes containing agostic contacts.20
The data gathered so far suggest that the structure
of 8 in solution and in the solid state are both very
similar. To substantiate this conclusion further, several
1H NOESY and ROESY and 31P NOESY (EXSY) NMR
spectra of 8 were recorded at two different temperatures
(-70 and -90 °C). The experiments employed different
mixing times in an attempt to address the dynamic
behavior of 8 in solution. We were particularly inter-
ested in determining whether Ha could be exchanged
between C11 and C12 (the Cipso). If this happens on the
NMR time scale of the applied techniques, one would
expect exchange cross-peaks between A,B, and C,D type
protons in an EXSY spectrum.
-90 °C showed no evidence for chemical exchange
involving Ha, it does show exchange cross-peaks within
benzylic and within aromatic ATA*, BTB*, CTC*,
DTD*, A(*)TB(*), and C(*)TD(*) type protons. How-
ever, exchange between the two groups (i.e., A,BTC,D)
was not observed. This was confirmed by 31P NOESY
(EXSY) spectroscopy, in which the exchange PATPB and
PCTPD is clearly evident but not PA,BTPC,D. These
results indicate that on the time scale of the applied
NMR techniques the dynamic behavior in 8 is mainly
caused by the movement of the trans-P,P′-bidentate-
bonded PCHP ligand. This is not surprising if one
considers that the bidentate chelate is likely much more
flexible with respect to the tridentate η3-P,C,P′-coordi-
nated (formally monoanionic) PCP ligand. However, it
was not possible to establish whether the dynamic
behavior was caused by one single or several simulta-
neous mechanisms. Finally, it should be noted that
exchange of Ha between C11 and C12, which would
represent a degenerative process from the point of view
of 8, either does not occur or it does with a rate too small
to be detected by the techniques used. To verify whether
such exchange could be triggered at room temperature
(or above) and on a laboratory time frame, some chemi-
cal experiments were performed involving complexes
analogous to 8.
Ch em ica l Exp er im en ts In volvin g Exch a n ge Re-
a ction s betw een η3-P ,C,P ′-Coor d in a ted P CP a n d
P ,P ′-Coor d in a ted P CHP Liga n d s. To study whether
displacement of Ha from C11 to C12 could be a feasible
process, a different chelate-bonded meta-bisphosphi-
noarene ligand with a para substituent R * H was used.
In this case, migration of Ha between C11 and C12
would cause the formation of distinct compounds, [Ru-
(PCP)(R-PCHP)][OTf] and [Ru(R-PCP)(PCHP)][OTf],
which each would have unique spectroscopic features.
Therefore, complex 9 was synthesized in a reaction at
room temperature (in CH2Cl2) between [RuOTf(PCP)-
(PPh3)] (4) and the para-bromo-substituted ligand 2
(Scheme 2). Like the analogous complex 8, 9 is a yellow
solid with very similar spectroscopic features and is
highly fluxional in solution. In the 31P NMR spectrum
Interestingly, all the 1H NOESY spectra contained
strong cross-peaks having phase equal to the spectral
diagonal. Unfortunately, this situation makes it impos-
sible to differentiate between NOE and chemical ex-
change cross-peaks. This problem could be solved by
using ROESY NMR spectroscopy, in which cross-peaks
due to chemical exchange appear with an inverted phase
in relation with cross-peaks arising from NOE effects.38
(38) (a) Braun, S.; Kalinowski, H.-O.; Berger, S. 100 and More Basic
NMR Experiments. A Practical Course; VCH: Weinheim, Germany,
1996; p 330. (b) Freeman, R. Spin Choreography: Basic Steps in High-
Resolution NMR; Spektrum, Oxford, England, 1997; p 295.
(37) Friebolin, H. Basic One- and Two-Dimensional NMR Spectros-
copy, 2nd ed.; VCH: Weinheim, Germany, 1993; p 127.

5294 Organometallics, Vol. 19, No. 25, 2000
Sch em e 4. Isom er iza tion Rea ction Obser ved w ith Com p lex 9
Dani et al.
Sch em e 5. Mech a n istic P r op osa l for th e Isom er iza tion Rea ction Obser ved w ith 9
at -70 °C, a set of four multiplets of an ABMN spin
system is observed, and in the 1H NMR spectrum at the
same temperature a broad singlet is present at 1.08
ppm. The same NMR analyses performed with 8 were
used to characterize 9. In this way, the signal at 1.08
comes from the chemical shift of this particular carbon
in the 13C NMR spectrum of the free ligands 1 (δ )
130.46 ppm)31 and 2 (δ ) 129.38 ppm).22 Therefore,
there is an upfield shift of (∆δ ) δ1-δ2) 1.08 ppm for
the carbon of ligand 2, suggesting an increase of the
electron density over this carbon. Similar analysis has
already been employed for other compounds containing
NCN39 and PCP40 “pincer” ligands.
1
ppm in the H NMR spectrum was clearly established
as the resonance frequency of proton Ha in complex 9.
In a sealed NMR tube, a solution of 9 in CD2Cl2 was
1
kept at 40 °C for 40 min. After this period, a H NMR
The second piece of evidence is related to the observed
difference in chemical shift of Ha in complexes 8 or 13
(δHa ) 1.23 ppm) and 9 (δHa ) 1.08 ppm) in the 1H
NMR spectrum. It is reasonable to assume that these
complexes have similar structures, and therefore, the
origin for such chemical shift difference should be
electronic in nature. Hence, the shielding effect observed
in the chemical shift of Ha in 9 also suggests that the
C-Ha bond in this complex has a higher electron density
than the same bond in 8 or 13. Taking into account
these two factors, the isomerization shown in Scheme
4 is likely to happen via an electrophilic aromatic
substitution mechanism involving arenium-type inter-
mediates, like A and A′, and a transition state (or very
reactive intermediate) containing two trans C12-Ru-
C11 bonds (X, Scheme 5). The participation of arenium
species in the formation of metal-carbon bonds has
been the subject of a number of studies involving late
transition metal complexes of “pincer” ligands.41,42
Furthermore, the transfer of an aromatic proton of a
PCHP ligand to an η3-N,C,N′ metal bonded NCN ligand
has been observed and identified by us as transcyclo-
spectrum at -70 °C showed the presence of a second
broad singlet at 1.23 ppm, the same chemical shift in
which Ha of 8 is observed. In the 31P NMR spectrum,
also at -70 °C, two ABMN spin systems were present.
Their independence was confirmed by a 31P-31P COSY
NMR spectrum. The logical explanation for these ob-
servations is that 9 is being isomerized into complex 13
(Scheme 4). No isomerization reaction was observed at
temperatures below 25 °C. Complete conversion of 9 into
13 could not be achieved due to decomposition of these
complexes in dichloromethane solution in a way similar
to that observed for pure 8.
The reaction depicted in Scheme 4 shows that the
conversion of the metalated site into the nonmetalated
one is possible in the case of complex 9. The fact that
the process was only effective at temperatures above 25
°C indicates that the energy barrier for the intercon-
version is relatively high. The greater thermodynamic
stability of 13 over 9 is likely to be the result of
electronic differences caused by the nature of the para-
substituent R (H or Br). In terms of electrophilic
aromatic substitution, halogens are considered ortho/
para directors and electron-withdrawing substituents.
However, there are two pieces of evidence that suggest
that the C-Ha carbon atom in 9 can have an electron
density greater than the same carbon in 8. The first one
(39) van de Kuil, L. A.; Luitjes, H. Grove, D. M.; Zwikker, J . W.;
van der Linden, J . G. M.; Roelofsen, A. M.; J enneskens, L. W.; Drenth,
W.; van Koten, G. Organometallics 1994, 13, 468-477.
(40) Weisman, A.; Gozin, M.; Kraatz, H.-B.; Milstein, D. Inorg.
Chem. 1996, 35, 1792-1797.

Complexes of Bisphosphinoaryl Ru(II) Cations
Organometallics, Vol. 19, No. 25, 2000 5295
metalation (TCM) reactions.31 These TCM reactions
have been applied as a tool for the synthesis of Ru-
PCP31 and Pt-PCP32 complexes as well as for the
alternative synthesis of 8 from the reaction of [RuOTf-
(NCN)(PPh3)], 7, with PCHP (1) presented here; see
Scheme 2. In these cases, there are strong indications
that the proton transfer from the PCHP to the NCN
ligands occurs via an intramolecular mechanism as-
sisted by the amino groups of the NCN ligand. Whether
the same mechanism can be operative here for the case
of 9, in which only phosphorus ligands are present, is
still a matter of further studies. However, it should be
noted that exchange of Ha in 8 by deuterium via simple
solubilization of this complex in CD3OD was not ob-
served.
It is very likely that the same isomerization observed
with 9 is also happening with 8. In fact, an equilibrium
should be present between the two possible (degenerate)
isomers. At low temperatures (around -70 °C), the rate
constant for this process should be quite small since one
does not observe any characteristic cross-peaks in the
1H and 31P NOESY analysis involving exchange of the
type A,BTC,D. Indeed, the need for heating 9, which
leads to 13, is a reflection of this aspect.
synthesized as described in the literature. Me3SiOTf and
nBuLi were purchased commercially. 1H, 13C, and 31P NMR
spectra were recorded on a Varian Unity Inova 300 MHz
spectrometer using standard pulse sequences. Chemical shifts
are reported in ppm from (CH3)4Si or from the solvent peak
(1H and 13C NMR spectra) and from a capillary containing 85%
H3PO4 (31P NMR spectra). All deuterated solvents were de-
gassed prior to use (4 times) using the freeze-pump-thaw
methodology and stored under nitrogen over 4 Å molecular
sieves. The NMR experiments with complexes such as 8 were
typically performed by transferring ca. 30 mg of the complex
dissolved in 0.7 cm3 of CD2Cl2 to a 5 mm NMR tube containing
a glass stopper. Except for the NOESY, TOCSY, and ROESY
experiments, all other two-dimensional experiments were
performed in a non-phase-sensitive mode. The second pulse
1
in the H-1H COSY experiment was set to 45°. Normal-range
1
13C-1H COSY spectra were recorded considering J HC ) 140
Hz. T1 times for protons of complexes such as 8 fall in the range
0.4-1.5 s. 1H NOESY experiments were recorded with mixing
1
times 0.2, 0.5, 0.8, 1.0, and 1.5 s and H ROESY with mixing
times of 0.1 and 0.5 s. 31P EXSY spectra were recorded with
mixing times of 0.5 and 1.0 s.
Syn th esis of C6H3(CH2P P h 2)2-1,3-D-2 (1-D). To a solution
of C6H3(CH2Br)2-1,3-D-2 in xylene was added 2 equiv of
EtOPPh2. After 2 h of heating to reflux temperature, the
volatiles were removed and the remaining residue was ex-
tracted with hexane. This resulted in the formation of the
corresponding phosphine oxide as a white solid. The reduction
was performed by adding an excess of HSiCl3 dropwise to a
hot solution of the phosphine oxide in benzene. The volatiles
were removed in vacuo, and the oily residue was treated with
hexane to induce crystallization. The formed white waxlike
precipitate was filtered off and dried under vacuum. Yield:
70% (based on C6H3(CH2Br)2-1,3-D-2). 1H NMR (300 MHz,
CDCl3): δ 3.41 (s, 4H, CH2), 6.89 (m, 2H, CH-4,6), 7.06 (t, 1H,
CH-5, 3J HH ) 8 Hz), 7.38 (m, meta-H of PPh2), 7.44 (m, para-H
of PPh2), 7.48 (m, ortho-H of PPh2). 13C{1H} NMR (75 MHz,
Con clu sion s
We have detailed the synthesis, characterization, and
reactivity of ruthenium complexes containing bisphos-
phinoaryl and biphosphinoarene ligands in which one
is η3-P,C,P′ bonded to the metal and the other is η2-
P,P′ bonded via the phosphorus groups only. The
aromatic C-Ha bond (see Figure 3) of the bidentate
meta-bisphosphinoarene ligand has an agostic interac-
tion with the ruthenium center. 31P-1H COSY NMR
spectroscopy was successfully used in order to precisely
locate the resonance of this proton in the 1H NMR
spectrum. Compounds containing agostic contacts are
frequently indicated as possible intermediates in metal-
carbon bond formation. In the work reported herein, it
was possible to observe the actual formation of a new
Ru-C bond at the expense of another Ru-C bond,
probably via an electrophilic aromatic pathway. Finally,
complex 7 (containing a cyclometalated terdentate
bisaminoaryl ligand) was introduced as a new ruthe-
nium starting material capable of the delivery of a RuII
nucleus to form new cyclometalated species.
1
CDCl3): δ 35.89 (d, CH2, J CP ) 16 Hz), 126.99 (m, CH-4,6),
3
128.12 (s, CH-5), 128.34 (d, meta-H of PPh2, J CP ) 7 Hz),
2
128.65 (s, para-H of PPh2), 132.90 (d, ortho-H of PPh2, J CP
)
2
4
18 Hz), 137.33 (dd, C-1,3, J CP ) 8 Hz, J CP ) 2 Hz), 138.33
(d, C-P, J CP ) 15 Hz). 31P{1H} NMR (121 MHz, CDCl3): δ
1
-9.52 (s).
Syn th esis of C6H3(CH2P P h 2)2-3,5-Br -1 (2). A three-neck
500 cm3 round-botton flask containing an ammonia condenser
and a magnetic stirring bar was connected to a nitrogen line
and then immersed in an acetone-dry ice bath. Condensing
of ammonia (about 250 cm3) was followed by addition of small
sodium cuts (1.38 g, 60 mmol). After 30 min, solid PPh3 (7.87
g, 30 mmol) was added to the intense blue-colored solution.
The color of the mixture almost immediately changed to pale
yellow. After 40 min, dry ammonium bromide (2.94 g, 30 mmol)
was slowly added followed after 15 min by solid C6H3(CH2-
Br)2-3,5-Br-1 (5.14 g, 15 mmol), which was added in a single
portion. The acetone-dry ice bath was then removed. After
evaporation of the ammonia (4 h), degassed water (200 cm3)
and diethyl ether (200 cm3) were added. The organic layer was
transferred to another round-bottom flask using a cannula.
The water layer was extracted with diethyl ether (2 × 100
cm3). The combined organic fractions were dried over magne-
sium sulfate. The magnesium sulfate was filtered off, and the
volatiles were removed in vacuo, resulting in the formation of
a white solid. Sometimes, crystallization from MeOH is neces-
sary. Yield: 60-70%. Anal. Calcd (Found) for C 69.45 (69.41),
Exp er im en ta l Section
Gen er a l Com m en ts. All experiments were conducted
under dry nitrogen atmosphere using standard Schlenk tech-
niques. Solvents were dried over appropriate materials and
distilled prior to use. [RuCl2(PPh3)3],43 1,4 5,44 and 828 were
(41) (a) van Koten, G.; Timmer, K.; Noltes, J . G.; Spek, A. L. J .
Chem. Soc., Chem. Commun. 1978, 250-252. (b) Grove, D. M.; van
Koten, G.; Louwen, J . N.; Noltes, J . G.; Spek, A. L.; Ubbels, H. J . C. J .
Am. Chem. Soc. 1982, 104, 6609-6616. (c) Albrecht, M.; Gossage, R.
A.; Spek, A. L.; van Koten, G. J . Am. Chem. Soc. 1999, 121, 11898-
11899.
(42) (a) van der Boom, M. E.; Ben-David, Y.; Milstein, D. J . Am.
Chem. Soc. 1999, 121, 6652-6656. (b) Vigalok, A.; Shimon, L. J . W.;
Milstein, D. J . Am. Chem. Soc. 1998, 120, 477-483.
(43) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth.
1970, 12, 237.
1
H 4.92 (4.88). Mp: 95-97 °C. H NMR (200 MHz, CDCl3): δ
3.26 (s, 4H, CH2), 6.75 (s, 1H, CH ortho to both CH2PPh2
groups), 6.91 (s, 2H, BrCCH), 7.20-7.45 (m, 20H, aromatic
protons). 13C{1H} NMR (CDCl3, 75 MHz): δ 35.94 (d, CH2, 1J CP
3
) 17 Hz), 122.15 (s, CBr), 128.71 (d, meta-C of PPh2, J CP ) 7
(44) Sutter, J .-P.; J ames, S. L.; Steenwinkel, P.; Grove, D. M.;
Veldman, N.; Smeets, W. J . J .; Spek, A. L.; van Koten, G. Organome-
tallics 1996, 15, 941-948.
3
Hz), 129.14 (s, para-C of PPh2), 129.38 (t, CH-4, J CP ) 7
2
Hz), 130.14 (d, Br-C-CH), 133.14 (d, ortho-C of PPh2, J CP
)

5296 Organometallics, Vol. 19, No. 25, 2000
Dani et al.
1
19 Hz), 138.07 (d, Cquat of PPh2, J CP ) 15 Hz), 139.77 (d,
became green colored, and gradually yellow crystals of 8
separated out. These crystals were collected and analyzed by
1H and 31P NMR spectroscopy in CD2Cl2, which confirmed the
exclusive formation of 8.
C-CH2PPh2, J CP ) 9 Hz). 31P{1H} NMR (CDCl3, 81 MHz): δ
2
-9.07 (s).
Syn th esis of [Ru (OTf)(C6H3{CH2NMe2}2-2,6)(P P h 3)] (7).
To a Schlenk tube containing 5 (0.1870 g, 0.32 mmol) dissolved
in benzene (30 cm3) was added Me3SiOTf (0.2 cm3, 0.96 mmol).
After stirring for 22 h at room temperature, the initially blue
solution became purple. The volatiles were pumped off, and
the solid residue was washed with pentane (5 × 3 cm3) and
dried in a vacuum, yielding a purple solid. Yield: 0.1577 g
(70%). 1H NMR (200 MHz, C6D6): δ 1.97 (s, 6H, CH3), 2.00 (s,
Syn th esis of [Ru (P CP )(P CDP )][OTf] (8-D) a n d [Ru -
(P CP )(Br -P CHP )][OTf] (9). Both 8-D and 9 were synthe-
sized by the reported procedure for 828 using ligands 1-D (for
8-D) and 1-C6H3(CH2PPh2)2-3,5-Br-1, 2 (for 9). Characteriza-
tion of 9: 1H NMR (300 MHz, CD2Cl2, -70 °C): δ 1.08 (bs,
1H, Ha), 2.35-4.20 (m, 8H, CH2), 5.0-8.20 (m, 45H, aromatic
protons). 31P{1H} NMR (121 MHz, CD2Cl2, -70 °C): δ 16.55
3
6H, CH3), 2.35 (s, 4H, CH2), 6.72 (d, 2H, H-3,5, J HH ) 7.4
2
2
(dt, 1P, PA, J PP ) 274 and 29 Hz), 20.43 (dt, 1P, PB, J PP
)
Hz), 6.85-7.10 (m, 11H, m,p-H of PPh3 protons and H-4),
7.50-7.62 (m, 6H, o-H of PPh3 protons). 31P{1H} NMR (81
MHz, C6D6): δ 87.23 (s).
274 and 30 Hz), 30.89 (dt, 1P, PC, 2J PP ) 230 and 31 Hz), 45.79
2
(dt, 1P, PD, J PP ) 230 and 27 Hz). Anal. Calcd (Found) for
C65H54BrF3O3P4RuS‚1.5CH2Cl2: C 56.87 (56.25), H 4.09 (4.12),
Br 5.69 (5.65), P 8.82 (8.72).
Syn th esis of [Ru (P CP )(P CHP )][OTf] (8) fr om [Ru -
(OTf)(NCN)P P h 3] (7). PCHP (1, 1.5 equiv) was added to a
solution of 7 in C6D6 at RT. The resulting solution was kept
at 60 °C for 12 h. During this period, the purple solution
OM0005001