New features of bis(phosphinimine)- carbene binding to Ru II

Article abstract of DOI:10.1021/om050180r

Analysis of the results of DFT(PBE) calculations on a variety of species containing a RuC-(PPh₂NPh)₂ subunit led to the proposal that this should be considered as an example where an Ru/C single bond is present, which leaves a stereochemically active lone pair on the carbene carbon and thus a pyramidal, quasi-sp³ hybridization for carbon. General applications of this idea are discussed, the possible protonation of this carbon lone pair is described, and a DFT(PBE) geometry optimization of the two species (Cl)_nRuHC(PPh ₂NPh)₂^(1-n)+ with n = 0, 1 reveals a potential for oxidative addition of the P/N bond of this ligand to Ru, to generate an RuNPh moiety. The crystal structure of the triflate (CF₃SO ₃^-) salt of the C-protonated species (Cymene) Ru[H*C(PPh₂NPh]₂]⁺ shows that H* hydrogen bonds to triflate.

Full text of DOI:10.1021/om050180r

Organometallics 2005, 24, 3849-3855
3849
New Features of Bis(phosphinimine)-“carbene” Binding
to RuII
Yegor Smurnyy, Christine Bibal, Maren Pink, and Kenneth G. Caulton*
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, and
M.V. Lomonosov Moscow State University, Moscow, Russia 119992
Received March 10, 2005
Analysis of the results of DFT(PBE) calculations on a variety of species containing a “RuC-
(PPh2NPh)2” subunit led to the proposal that this should be considered as an example where
an Ru/C single bond is present, which leaves a stereochemically active lone pair on the
“carbene” carbon and thus a pyramidal, quasi-sp3 hybridization for carbon. General
applications of this idea are discussed, the possible protonation of this carbon lone pair is
(1-n)+
described, and a DFT(PBE) geometry optimization of the two species (Cl)nRuHC(PPh2NPh)2
with n ) 0, 1 reveals a potential for oxidative addition of the P/N bond of this ligand to Ru,
-
to generate an RuNPh moiety. The crystal structure of the triflate (CF3SO3 ) salt of the
C-protonated species (Cymene)Ru[H*C(PPh2NPh]2]+ shows that H* hydrogen bonds to
triflate.
Introduction
resonance contributors to a doubly reduced form. Sev-
eral examples where I is bidentate, through C and one
N, to a metal (Pt) seem well-described as carbenes,7 in
these d8 and planar species.
We have been attracted to examine the highly varied
coordination chemistry of bis-phosphinimine methanes,
H2C(PR2NR′)2, and their related single and double
deprotonation products. The singly deprotonated monoan-
ion can bind η2 through two N or η3, through two N and
the nucleophilic ring carbon. The latter form shows
puzzling variability in the M/C distance, which we note
but do not address here.1-5 Instead, we focus here on
the fully C-dehydrogenated form, I, which has the
characteristics of a carbene, but one whose substituents
are unusual in that both are electron-withdrawing
groups.6 Because I is not known in the free state, but
Results
Goals. Our approach has been to carry out DFT
(PBE) geometry optimization of structures, including
isomeric structures, concurrent with synthetic work
with this ligand class attached to d6, Ru(II) species.8
This can identify which structures are not energy
minima, as well as predict favored isomers from among
several candidates. Given the unusual experimental
structural and electronic features discussed above, the
DFT results may also help to understand bond order
and ligand atom hybridization; no self-consistent picture
of these characteristics has emerged thus far for these
unusual “carbenoid” ligands bearing two electron-
withdrawing groups. In fact, the DFT calculations
reported here permit a completely new interpretation
of this metal carbenoid bond and also point the way to
intriguing new synthetic goals.
(Arene)Ru[C(PPh2NPh)2]. Our particular goal was
to contrast the available coordination chemistry of
C(PR2NR′)2 on early transition metals9-12 with low d
electron counts by the study of late metal complexes
with higher d electron counts. Using all atoms of
only coordinated to metals, its charge when coordinated
to a metal can be ambiguous, and II and III show two
(7) Jones, N. D.; Lin, G.; Gossage, R. A.; McDonald, R.; Cavell, R.
G. Organometallics 2003, 22, 2832-2841.
(1) Hill, M. S.; Hitchcock, P. B. J. Chem. Soc., Dalton Trans. 2002,
4694-4702.
(8) Bibal, C.; Pink, M.; Smurnyy, Y. D.; Tomaszewski, J.; Caulton,
K. G. J. Am. Chem. Soc. 2004, 126, 2312-2313.
(9) Cavell, R. G.; Babu, R. P. K.; Kasani, A.; McDonald, R. J. Am.
Chem. Soc. 1999, 121, 5805-5806.
(2) Evans, D. J.; Hill, M. S.; Hitchcock, P. B. Dalton Trans. 2003,
570-574.
(3) Wei, P.; Stephan, D. W. Organometallics 2002, 21, 1308-1310.
(4) Gamer, M. T.; Dehnen, S.; Roesky, P. W. Organometallics 2001,
20, 4230-4236.
(10) Kamalesh Babu, R. P.; Cavell, R. G.; McDonald, R. Chem.
Commun. (Cambridge) 2000, 481-482.
(5) Gamer, M. T.; Roesky, P. W. J. Organomet. Chem. 2002, 647,
123-127.
(11) Aparna, K.; Ferguson, M.; Cavell, R. G. J. Am. Chem. Soc. 2000,
122, 726-727.
(6) Davies, H. M. L.; Beckwith, R. E. J. Chem. Rev. (Washington,
DC) 2003, 103, 2861-2903.
(12) Watson, L. A.; Yandulov, D. V.; Caulton, K. G. J. Am. Chem.
Soc. 2001, 123, 603-611.
10.1021/om050180r CCC: $30.25 © 2005 American Chemical Society
Publication on Web 06/30/2005

3850 Organometallics, Vol. 24, No. 16, 2005
Smurnyy et al.
Figure 2. Calculated (DFT) structure of (Cymene)Ru η3-
[C(PPh2NPh)2]. Only the ipso carbons of phenyl groups are
shown.
Figure 1. Calculated (DFT; distances in Å) structure of
(Cymene)Ru η2-[C(PPh2NPh)2]. Only the ipso carbons of
phenyl groups are shown.
(Cymene)Ru[C(PPh2NPh)2] in a DFT(PBE) geometry
optimization led to two stationary points, both minima.
The first (A and Figure 1) has an η2-chelate ligand,
bound to Ru through a carbene carbon and one imine
nitrogen. The second imine nitrogen lone pair is not
Figure 3. Calculated structure of (Cymene)Ru[HC(PPh2-
NPh)2]+, showing only the ipso carbons of all phenyls.
bound to Ru, consistent with avoidance of a 20 valence
electron configuration at the metal. The CRuN plane is
essentially perpendicular to the cymene ring plane. The
Ru/C distance, 2.01 Å, is short enough to be considered
a double bond (compare 2.22 Å for a Ru-C(sp3) bond).13
This RudC double bond localizes the ring P-C as a
single bond and the P/N bond as double, in agreement
with the bond lengths shown. The carbene carbon is
nearly planar (angles sum to 357.2°).
present in C because a pair of electrons is localized on
carbon. The Ru/C single bond implied by D is consistent
The second minimum energy structure (B and Figure
2) is remarkable for having an η3 “carbene” ligand.
Equally remarkable is the fact that its energy is so
similar to that of A: B is only 5.0 kcal/mol higher in
free energy than A. We initially doubted this structure
since it appeared to involve 20 valence electrons around
Ru (assuming an RudC double bond) and thus reflects
occupancy of a high-lying orbital. The Ru-C(cymene)
distances gave no support for η4-cymene binding. The
alternative structure C would leave the carbene carbon
truly unsaturated (the two carbene substituents, being
electron withdrawing, cannot diminish this problem).
It also requires energetically costly reduction of Ru, to
Ru(0). However, if a σ bond exists between Ru(II) and
carbon (D), then a Ru/C bond is formed without increas-
ing the metal valence electron count above the 18
with the 2.28 Å distance found in this DFT structure
(much longer than in A). Also persuasive of this bonding
picture is the highly pyramidal nature of the chelate
ring carbon (the three angles sum to 293.9°), which
confirms that there is a lone pair on this carbon, and
thus the Ru/C bond is single, leaving a stereochemically
active lone pair on carbon. The corresponding angle sum
after protonation of this carbon (see next section and
Figure 3) is 300.9°. The calculated14,15 NBO charge on
this carbon in D is remarkably negative (-1.17 e).
(14) Reed, A. E.; Weinstock, R. B.; Weinhold, F. J. Chem. Phys. 1985,
83, 735-46.
(15) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. Rev. (Washing-
ton, DC) 1988, 88, 899-926.
(13) Watanabe, M.; Murata, K.; Ikariya, T. J. Am. Chem. Soc. 2003,
125, 7508-7509.

Bis(phosphinimine)-“carbene” Binding to RuII
Organometallics, Vol. 24, No. 16, 2005 3851
Second-order perturbation theory analysis of the Fock
matrix in the NBO basis shows the absence of any
significant interaction of the carbon lone pair with any
metal atomic orbital. This supports the interpretation
of a carbon-localized lone pair. A comparison to phos-
phorus ylides, R3P+-C-H2, is thus appropriate.
While our work was under review, a publication
appeared16 on compound E and its deprotonation (de-
hydrochlorination) to give the carbene F, including a
crystal structure determination of F. The main differ-
Figure 4. ORTEP drawing (50% probability) of the non-
hydrogen atoms of (Cymene)Ru[HC(PPh2NPh)2]+, showing
selected atom labeling. The hydrogen on C1, which hydro-
gen bonds to triflate, is illustrated. Only the phenyl ipso
carbons are shown.
Table 1. [RuCH(PPh2NPh)2(cym)](CF3SO3)‚3THF
empirical formula
molecular weight
instrument
cryst color, shape
cryst size
cryst syst
space group
cell dimens (130 K)
a
C60H69F3N2O6P2RuS
1166.24
SMART6000
orange plate
0.21 × 0.18 × 0.10 mm3
monoclinic
ence from our work here is the strongly electron-
withdrawing substitutent on nitrogen in E and F. DFT
calculations on F yield a natural population analysis
charge on the carbene carbon of -1.19 e (which is much
more negative than the -0.015 e calculated there for
RuCl2(CH2)(PMe3)2), AND the authors analyze the
HOMO as an Ru/C π bond (together with an Ru-C σ
bond), which makes it analogous to our ground state
structure (A and Figure 1). Our 5 kcal/mol higher energy
isomer (i.e., η3-ligand binding to Ru) in Figure 2 was
not discussed in this recent work.
Protonation as Evidence of Bronsted Basicity
of Isomer D. If the pyramidal geometry reliably
indicates a lone pair on that carbon, it is reasonable to
seek evidence of this by studying protonation at that
site. Indeed, geometry optimization of (Cymene)Ru[HC-
(PPh2NPh)2]+ shows a minimum energy structure (Fig-
ure 3) that resembles a three-legged piano stool. Despite
protonation of the carbon, the Ru-C bond is retained.
The optimum geometry does not relax to (Cymene)Ru-
[η2-HC(PPh2NPh)2]+, where the chelate binds through
only two nitrogens. The Ru-C (single) bond length in
this structure is 2.25 Å, which further supports the idea
that only a Ru-C single bond exists in the deprotonated
species (Cymene)Ru[η3-C(PPh2NPh)2], which has Ru-C
) 2.28 Å (Figure 2).
Cc
28.993(3) Å
11.0780(11) Å
21.234(2) Å
90°
b
c
R
â
125.623(2)°
90°
γ
volume
5543.8(10) Å3
4
Z (molecules/cell)
calcd density
abs coeff
1.397 Mg/mm3
0.441 mm-1
final residuals
R1, observed data
wR2, all data
0.0446a
0.1095b
a R1 ) ∑(|Fo| - |Fc|)/∑|Fo|. b wR2 ) [∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2]]1/2
.
Table 2. Selected Bond Lengths [Å] and Angles
[deg] for the Cation (Cymene)Ru[HC(PPh2NPh)2]+
Ru1-C1
2.230(4)
1.618(4)
1.608(4)
2.131(19)
2.15(2)
2.172(10)
2.205(19)
84.92(15)
70.14(14)
97.7(2)
132.2(3)
131.2(3)
95.12(17)
89.27(17)
Ru1-N1
2.147(4)
2.175(4)
1.774(4)
1.752(4)
2.228(8)
2.245(10)
71.45(14)
97.7(2)
128.4(3)
97.85(17)
131.2(3)
119.4(2)
90.40(18
P1-N1
Ru1-N2
P2-N2
P1-C1
Ru1-C38
P2-C1
Ru1-C43
Ru1-C40
Ru1-C39
Ru1-C41
Ru1-C42
N1-Ru1-C1
N1-P1-C1
C2-N1-P1
P1-N1-Ru1
C32-N2-Ru1
P2-C1-P1
P1-C1-Ru1
N1-Ru1-N2
N2-Ru1-C1
N2-P2-C1
C2-N1-Ru1
C32-N2-P2
P2-N2-Ru1
P2-C1-Ru1
In effect, deprotonation (eq 1) of (Cymene)Ru[HC-
(PPh2NPh)2]+ leaves the electrons of the C-H bond
localized on that carbon. That carbon remains nonpla-
nar.
A synthesis of this C-protonated cation has been
accomplished (eq 2, Cym ) 4-iPr-toluene), as its triflate
(CF3SO3-) salt. A single-crystal X-ray crystallographic
determination of its structure (Figure 4 and Tables 1
and 2) shows good agreement with the DFT geometry-
optimized structure of the isolated cation, confirming
that the triflate counterion has no significant perturbing
influence on the cation structure. The Ru-CH(PPh2-
NPh)2 distance (2.230(4) Å) compares well to that from
the DFT calculation (2.25 Å). Of special interest is the
fact that one of the triflate oxygens, O3, forms a
hydrogen bond to the “methanide” hydrogen, with an
H1A‚‚‚O3 distance of 2.73 Å and an C1-H1A‚‚‚O3 of
(1) LiHC(PPh2NPh)2
(Cym)RuCl2
8
(2) Me3SiOTf
(Cym)Ru[HC(PPh2NPH)2]+ + F3CSO3- + Me3SiCl
(16) Cadierno, V.; Diez, J.; Garcia-Alvarez, J.; Gimeno, J.; Calhorda,
M. J.; Veiros, L. F. Organometallics 2004, 23, 2421-2433.
(2)

3852 Organometallics, Vol. 24, No. 16, 2005
Smurnyy et al.
Figure 6. Calculated structure of ClRu(NPh)[η2-HC(PPh2-
NPh)PPh2].
Figure 5. Calculated structure of ClRu[η2-HC(PPh2-
NPh)2], showing chair conformation of the six-membered
ring.
157.6°. This is therefore experimental evidence that this
is a positively polarized H on carbon and thus a
candidate for the Bronsted acid/base reaction of eq 1.
In summary, deprotonation of the unique carbon
produces a pair of electrons on the ligand. While the
more stable product involves forming a Ru/C π bond
while displacing one Ru/N bond (i.e., product A), only 5
kcal/mol worse is retention of these electrons as a lone
pair on carbon, keeping both Ru/N bonds.
More Unsaturated Analogues. Exploration of a
more unsaturated species, Ru[HC(PPh2NPh)2]Cl, has
led to new insights about how this bis(phosphinimine)
ligand might react toward highly unsaturated metals.
In the absence of the six electrons donated to Ru by the
cymene ligand, one stationary point on the potential
energy surface is an η2-ligand structure (Figure 5) where
the metal is three-coordinate and planar, the six-
membered ring is nonplanar and in a chair conforma-
tion, and the structure has idealized mirror symmetry
(G). It is important to note that the ring conformation
leaves the nitrogens coplanar with its attached Ru, C
(ipso), and P and that this tends to reduce vicinal Ph-
(N)/Ph(P) repulsions. In response to the unsaturation
at Ru, the Ru-N distances are very short and the P-N
distances are long (cf. Figure 3), consistent with par-
ticipation by resonance structure H. This charge-
Figure 7. Calculated structure of Ru(NPh)[η2-HC(PPh2-
NPh)PPh2]+.
thermodynamic preference for this P/N cleaved form
may be attributed to the increased valence electron
count coming from the NPh ligand. The latter is
significantly bent ( Ru-N-C(ipso) ) 111.9°), suggesting
RudN double bond character (Ru/N distance ) 1.81 Å).
We have done a parallel calculation on the analogue
where all the phosphorus substituents have been changed
from phenyl to methyl (to alter electrophilicity of the
PR2 groups), and the thermodynamic preference for the
P/N cleavage isomer is essentially unchanged in mag-
nitude (free energy 14.5 kcal/mol more stable than
ClRu[η2-HC(PMe2NPh)2]), and the structure is also little
changed: Ru-N ) 1.81 Å and Ru-N-Cipso ) 108.4°.
Thus, for this species, the ligand oxidation of Ru is not
critically dependent on an electron-withdrawing phenyl
on P.
Note that it is the carbon, not the newly reduced
trivalent phosphorus that donates to the metal in RuCl-
(NPh)[HC(PPh2)PPh2NPh]. Although the imide ligand
is not linear (i.e., not donating its maximum) in ClRu-
(NPh)[HC(PPh2)(PPh2NPh)], the optimized geometry for
the product without a chloride ligand, i.e., the cation
Ru(NPh)[HC(PPh2NPh)]+, shows that the imide ligand
responds (Figure 7) to enhanced electron deficiency at
Ru by increasing the Ru-N-Cipso to 156.5° and a
shortened Ru/N distance of 1.76 Å. In this cation, Ru is
moving toward coplanarity with its three ligands: the
sum of angles at Ru is 351.5°. The HC-PPh2 distance
to trivalent P, 1.88 Å, is a useful comparison standard
of a single-bond distance. Other P-C distances reported
here are invariably shorter, due to delocalization of the
“carbene” lone pair toward PV.
separated form, with a P+-N- single bond, has been
emphasized recently.17 What is remarkable is that there
is another energy minimum, and this structure is more
stable by 13.0 kcal/mol (∆G°). In this (Figure 6), one P/N
bond has been cleaved. The Ru coordination number is
now four, because the ligand carbon now binds to Ru,
forming a (monoanionic)bidentate ligand via a four-
membered ring. The P/N bond cleavage occurs by two-
electron oxidation of Ru (i.e., the metal oxidation state
in Figure 5 is II, while in Figure 6 it is IV), and the
(17) Kocher, N.; Leusser, D.; Murso, A.; Stalke, D. Chemistry-A Eur.
J. 2004, 10, 3622-3631.

Bis(phosphinimine)-“carbene” Binding to RuII
Organometallics, Vol. 24, No. 16, 2005 3853
Figure 8. Representation of AO composition of the highest five filled orbitals of (Cym)Ru[η3-C(PPh2NPh)2] showing the
ring carbon “lone pair” (HOMO-1) and three doubly occupied, mainly d orbitals.
Discussion
Oxidation State Ambiguity. Reports of the (R′Nd
PR2)2C: carbene on four-coordinate platinum, but in a
planar metal coordination geometry, have twice7,18 been
recognized as somewhat paradoxical (PtII vs Pt0, the
latter most often tetrahedral). At the heart of this
paradox is the question of “correct” oxidation state for
this carbene. To better understand this and the related
Figure 9. Drawing of the nuclear positions (labeled), bond
paths (pink), and (3; -1) bond critical points (red), showing
bonds, for (Cym)Ru[η3-C(PPh2NPh2].
question of M/C bond order, we next analyze the orbitals
and the electron density calculated for the isomer D
(Figure 2) of (Cymene)Ru[η3-C(PPh2NPh)2].
Orbital Character of Ru/C Bonding. Examination
of the orbitals of this less stable isomer D of (Cymene)-
Ru[C(PPh2NPh)2], with an η3-ligand, shows the tran-
sannular Ru/C orbital interaction. Figure 8 shows that
the HOMO, HOMO-2, and HOMO-3 are mainly local-
ized on the metal and give a d6 electron count charac-
teristic of Ru(II). HOMO-1 is the carbon lone pair,
directed outward (i.e., away from Ru) and in the P-C-P
plane. HOMO-4 is the Ru/C (single) bond and involves
primarily that carbon orbital that is perpendicular to
the P-C-P plane.
A map of the bond critical points19 (Figure 9) is
consistent with these conclusions from Lewis structures,
and also from the orbital contours, in showing Ru-N,
(18) Lin, G.; Jones, N. D.; Gossage, R. A.; McDonald, R.; Cavell, R.
G. Angew. Chem., Int. Ed. 2003, 42, 4054-4057.
(19) Bader, R. F. W. Atoms in Molecules: A Quantum Theory; Oxford
University Press: Oxford, 1990.

3854 Organometallics, Vol. 24, No. 16, 2005
Smurnyy et al.
Scheme 1
of cleavage of a PdN bond was the energy minimum
optimized starting from the intact HC(Ph2PdNPh)2
group on a (highly) unsaturated Ru(II) center gives
cause for optimism that geometry searches using DFT
can truly make discoveries beyond the intuition of the
investigator. This is a very powerful accomplishment
of the method; theory leads rather than follows. Cleav-
age of PdN bonds in bis-phosphimine methanide ligands
therefore might be observed experimentally. Moreover,
the ability of the geometry search algorithm to find a
path that actually cleaves a P/N bond suggests that any
barrier between the starting and final geometries, if it
exists, must be less than about 5-10 kcal/mol, and thus
the bond cleavage mechanism on the singlet energy
surface will in actuality be kinetically facile at modest
temperature.
Table 3. Bond Ellipticities in
(Cymene)Ru[η3-C(PPh2NPh2]
Ru-N
N-P
P-C
Ru-C
ellipticity
0.229
0.123
0.072
0.043
N-P, and P-C bonds (bond critical points in red). The
bond critical point between Ru and C shows that the
Ru/C internuclear vector thus qualifies as a “bond” in
the same way as do the Ru-N, NP, and P-C vectors.
The character (single or double) of this Ru/C interaction
is revealed by the ellipticity parameters.
Ellipiticity19 is a ratio of two negative eigenvalues of
Hessian of the electron density. The Hessian matrix is
calculated at the bond critical point (i.e., (3:-1) critical
point). It can be rationalized as a measure of how
cylindrically symmetric a bond is at the critical points
in Figure 9. In particular, it can be used to distinguish
a σ single bond from a σ + π double bond. While a
cylindrically symmetric σ bond has ellipiticity near zero,
the elongated cross section of a π bond (Scheme 1) has
nonzero ellipticity (which is defined as a/b - 1, calcu-
lated at the bond critical points in Figure 9). The
ellipticity values shown in Table 3 confirm that the P/N
bond contains considerable π character, with some P/C
π character. The Ru/C bond contains the least π-char-
acter, consistent with it being a single (and σ) bond. The
π character indicated for the Ru/N bond is consistent
with participation by resonance structure J, which
delocalizes negative formal charge away from carbon,
and also accounts for the nonzero ellipticity value for
the P/C bond.
Finally, others22 have recently reported an analogous
bonding situation K in a closely related ligand. Their
conclusion, like ours here, is that a Pd-C single bond
exists, together with a carbon-centered lone pair. The
noteworthy geometric feature is a pyramidal carbon.
Experimental Section
Computational Details. Theoretical calculations in this
work have been performed using density functional theory,23
with the PBE24 functional, implemented in an original program
package “Priroda” authored by Dr. D. N. Laikov.25,26 Relativ-
istic Stevens-Basch-Krauss (SBK) effective core potentials
(ECP)27-29 optimized for DFT calculations have been used. A
Gaussian-type TZ2p basis set was used: Ru [5,1,1,1,1/5,1,1,1,1/
5,1,1,1], C,N,P,Cl [3,1,1/3,1,1/1,1], H [3,1,1/1]. Full geometry
optimizations have been performed without symmetry con-
straint. For all species under investigation, frequency analysis
has been carried out, and zero-point vibration energy correc-
tions have been made. All energies given are Gibbs standard
free energies (298 K). During the frequency analysis, second
derivatives were evaluated analytically. All geometries have
been checked for the absence of imaginary frequencies. Topo-
logical analysis of the density function was performed with
the XAIM package.30 The wave function was obtained using
the Gaussian 98 package;31 a single-point calculation (DFT,
PBE functional, custom TZ2p basis set) was performed using
the previously optimized geometry, and no ECP was intro-
duced.
(21) Musaev, D. G.; Morokuma, K. J. Am. Chem. Soc. 1995, 117,
799-805.
Perspective. It is valuable to document the extent
to which DFT-based geometry searches can actually
reveal unanticipated structures: those that involve
more than mere angular distortions and bond length
changes but represent instead formation or breaking of
bonds. For example, in studying the transition state for
C-H bond cleavage by RhCl(PH3)2, a σ bond complex
of intact methane RhCl(PH3)2(η2-HCH3) was found20 as
an energy minimum (not merely a transition state). The
same discovery was true of (C5H5)Rh(CO) with meth-
ane.21 The fact that, in the present work, the product
(22) Cantat, T.; Mezailles, N.; Ricard, L.; Jean, Y.; Le Floch, P.
Angew. Chem., Int. Ed. 2004, 43, 6382-6385.
(23) Parr, R. G.; Yang, W. Density-functional Theory of Atoms and
Molecules; 1989.
(24) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996,
77, 3865-3868.
(25) Laikov, D. N. Chem. Phys. Lett. 1997, 281, 151-156.
(26) Ustynyuk, Y. A.; Ustynyuk, L. Y.; Laikov, D. N.; Lunin, V. V.
J. Organomet. Chem. 2000, 597, 182-189.
(27) Cundari, T. R.; Stevens, W. J. J. Chem. Phys. 1993, 98, 5555-
65.
(28) Stevens, W. J.; Basch, H.; Krauss, M. J. Chem. Phys. 1984, 81,
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Chem. 1992, 70, 612-630.
(20) Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1993, 115, 6883-
92.
(30) Ortiz, J. C.; Bo, C. Universitat Rovira i Virgili, Tarragona,
Spain.

Bis(phosphinimine)-“carbene” Binding to RuII
Organometallics, Vol. 24, No. 16, 2005 3855
General Experimental. All synthetic work described was
carried out using standard Schlenk techniques or a glovebox
filled with argon. Solvents were dried and degassed before use.
H2C(PPh2NPh)2 and (RuCl2Cym)2 were synthesized according
to the literature procedures.32,33
1JP/C ) 86.1 Hz); 18.17 (s, CAH3); 22.41 (s, CBH3); 30.30 (s, CCH);
81.12 (s, CFH); 83.82 (s, CGH); 96.10 (s, CD); 106.19 (s, CE);
3
121.18 (s, CLH); 124.38 (d, CJH, JP/C ) 13.0 Hz); 128.58 (d,
3
3
CSH, JP/C ) 12.2 Hz); 129.22 (s, CK); 129.83 (d, COH, JP/C
)
12.2 Hz); 130.94 (d, CQ, 1JP/C ) 71.3 Hz); 131.60 (d, CRH, 3JP/C
1
3
Preparation of CymRuCH(PPh2NPh)2+Cl-.Methyllithium
) 11.5 Hz); 131.71 (dd, CM, JP/C ) 84.7 Hz, JP/C ) 8.7 Hz);
3
132.28 (s, CTH); 132.41 (d, CNH, JP/C ) 10.7 Hz); 133.48 (s,
CP); 148.82 (s, CI). FAB MS (m, intensity): 801 (M, 28), 667
(M - cym, 100), 589 (M - cym - H+ - Ph, 26).
Preparation of CymRuCH(PPh2NPh)2+OTf-. Me3SiOTf
(10 µL, 0.05 mmol) was added with a microsyringe to a solution
of CymRuCH(PPh2NPh)2+Cl- (25 mg, 0.03 mmol) in benzene.
Single crystals were obtained from a solution of CymRuCH-
(PPh2NPh)2+OTf- in THF cooled at -25 °C for several days.
1H NMR [400.1 MHz, C6D6] (δ, ppm): 0.55 (d, C(HB)3, 3JH/H
)
3
7.2 Hz, 6H); 1.24 (s, C(HA)3, 3H); 1.98 (sept, CHC, JH/H ) 7.2
Hz, 1H); 3.12 (s, PCHP, 1H); 5.06 (d, HG, 3JH/H ) 5.6 Hz, 2H);
3
5.25 (d, HF, JH/H ) 5.6 Hz, 2H); 6.28-8.41 (m, aryl-H, 30H).
31P NMR [162.0 MHz, C6D6] (δ, ppm): 35.53 (s). 13C NMR
[100.6 MHz, C6D6] (δ, ppm): -22.71 (t, PCHP, 1JP/C ) 86.9 Hz);
17.89 (s, CAH3); 22.22 (s, CBH3); 30.07 (s, CCH); 81.25 (s, CFH);
84.05 (s, CGH); 95.49 (s, CD); 105.54 (s, CE); 120.77-149.62
(aryl-C).
(0.41 mmol, 0.26 mL) was added dropwise to a stirred solution
of CH2(PPh2NPh)2 (0.2 g, 0.35 mmol) in THF at room temper-
ature. After 20 min, the lithium salt (0.35 mmol) was slowly
added to the dimer (RuCl2Cym)2 (0.1 g, 0.17 mmol) in THF at
room temperature, and the reaction mixture was stirred
overnight. Solvent was removed under vacuum, and the
residue was extracted with toluene. A red powder was isolated
from the toluene-soluble fraction after cooling the solution at
-25 °C for 1 day (0.22 g, 78%). Mp: 218 °C (dec). 1H NMR
X-ray Structure Determination of {(Cymene)Ru[HC-
(PPh2NPh)2]}O3SCF3‚3THF. A red crystal (approximate
dimensions 0.21 × 0.18 × 0.10 mm3) was placed onto the tip
of a 0.1 mm diameter glass capillary and mounted on a
SMART6000 (Bruker) at 130(2) K. The data collection (Table
1) was carried out using Mo KR radiation (graphite monochro-
mator) with a frame time of 20 s and a detector distance of
5.0 cm. A randomly oriented region of reciprocal space was
surveyed to the extent of a sphere. Four major sections of
frames were collected with 0.30° steps in ω at different φ
settings and a detector position of -43° in 2θ. Data to a
resolution of 0.80 Å were considered in the reduction. Final
cell constants were calculated from the xyz centroids of 7374
strong reflections from the actual data collection after integra-
tion. The intensity data were corrected for absorption. The
ruthenium complex crystallizes with one triflate anion and
three molecules of THF. p-Cymene is disordered over two
positions (50:50), rotating almost 180°. The distance of Ru to
the center of the phenyl ring (C38, ...C43) is 1.70 Å and to the
center of the phenyl ring (C38d, ...C43d) 1.72 Å. Two THF
molecules are disordered over two positions and were refined
with a set of restraints and constraints.
3
[499.8 MHz, CD2Cl2] (δ, ppm): 0.74 (d, C(HB)3, JH/H ) 7 Hz,
3
6H); 1.53 (s, C(HA)3, 3H); 1.96 (sept, CHC, JH/H ) 7 Hz, 1H);
3
2.79 (s, PCHHP, 1H); 5.25 (d, HG, JH/H ) 6 Hz, 2H); 5.32 (d,
3
3
3
HF, JH/H ) 6 Hz, 2H); 6.82 (ddd, HS, JH/H ) 7.8 Hz, JH/H
)
4
3
4
8.0 Hz, JP/H ) 2.9 Hz, 4H); 6.94 (tt, HL, JH/H ) 7.3 Hz, JH/H
3
4
) 1.4 Hz, 2H); 7.01 (ddd, HR, JH/H ) 8.0 Hz, JH/H ) 1.3 Hz,
3JP/H ) 12.8 Hz, 4H); 7.10 (m, HT, JH/H ) 7.8 Hz, JH/H ) 1.3
3
4
5
3
3
Hz, JP/H ) 1.5 Hz, 2H); 7.21 (dd, HK, JH/H ) 7.3 Hz, JH/H
)
8.0 Hz, 4H); 7.25 (dd, HJ, 3JH/H ) 8.0 Hz, 4JH/H ) 1.4 Hz, 4H);
3
4
5
7.71 (m, HP, JH/H ) 7.0 Hz, JH/H ) 1.0 Hz, JP/H ) 1.6 Hz,
2H); 7.74 (ddd, HO, 3JH/H ) 7.0 Hz, 3JH/H ) 8.4 Hz, 4JP/H ) 2.6
Hz, 4H); 8.25 (ddd, HN, 3JH/H ) 8.4 Hz, 4JH/H ) 1.0 Hz, 3JP/H
)
12.1 Hz, 4H). 31P NMR [162.0 MHz, CD2Cl2] (δ, ppm): 34.23
(s). 13C NMR [125.7 MHz, CD2Cl2] (δ, ppm): -21.35 (t, CHH,
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Gaussian 98 (Revision; A.97); Gaussian, Inc.: Pittsburgh, PA, 1998.
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Acknowledgment. This work was supported by the
National Science Foundation. We also thank Prof. Y.
A. Ustynyuk (Moscow State University) for his support
of this project, and Dr. D. Laikov for use of his software.
Computations were done at the Russian Academy of
Sciences joint supercomputer center.
Supporting Information Available: Full crystallo-
graphic details as a cif file and also Cartesian coordinates of
all structures illustrated. This material is available free of
charge via the Internet at http://pubs.acs.org.
OM050180R