Coordinatively unsaturated semisandwich complexes of ruthenium with phosphinoamine ligands and related species: A complex containing (R,R)-1,2-bis((diisopropylphosphino)amino)cyclohexane in a new coordination form κ3P,P′,N-η2-P,N

Article abstract of DOI:10.1021/ic700674c

The syntheses of the chloro complexes [RU(η⁵-C ₅R₅)Cl(L)] (R = H, Me; L = phosphinoamine ligand) (1a-d) have been carried out by reaction of [(η⁵-C₅H ₅)RuCl(PPh₃)₂] or {(η⁵-C ₅Me₅)RuCl}₄ with the corresponding phosphinoamine (R,R)-1,2-bis((diisopropylphosphino)amino)cyclohexane), R,R-dippach, or 1,2-bis(((diisopropylphosphino)amino)ethane), dippae. The chloride abstraction reactions from these compounds lead to different products depending on the starting chlorocomplex and the reaction conditions. Under argon atmosphere, chloride abstraction from [(η⁵-C₅Me ₅)-RuCl(R,R-dippach)] with NaBAr′₄ yields the compound [(η⁵-C₅Me₅) Ru(κ³P,P′-(R,R)-dippachp)][BAr′₄] (2b) which exhibits a three-membered ring Ru-N-P by a new coordination form of this phosphinoamine. However, under the same conditions the reaction starting from [(η⁵-C₅Me₅)RuCl(dippae)] yields the unsaturated 16 electron complex [(η⁵-C₅Me ₅)Ru(dippae)][BAr′₄] (2d). The bonding modes of R,R-dippach and dippae ligands have been analyzed by DFT calculations. The possibility of tridentate P,N,P-coordination of the phosphinoamide ligand to a fragment [(η⁵-C₅Me₅)Ru]⁺ is always present, but only the presence of a cyclohexane unit in the ligand framework converts this bonding mode in a more favorable option than the usual P,P-coordination. Dinitrogen [(η⁵-C₅R ₅)Ru(N₂)(L)][BAr′₄] (3a-d) and dioxygen complexes [(η⁵-C₅H₅)Ru(O ₂)(R,R-dippach)][BPh₄] (4a) and [(η⁵-C ₅Me₅)Ru(O₂)(L)][BPh₄] (4b,d) have been prepared by chloride abstraction under dinitrogen or dioxygen atmosphere, respectively. The presence of 16 electron [(η⁵-C ₅H₅)Ru(R,R-dippach)]⁺ species in fluorobenzene solutions of the corresponding dinitrogen or dioxygen complexes in conjunction with the presence of [BAr′₄]^- gave in some cases a small fraction of [Ru(η⁵-C₅H₅) (η⁶-C₆H₅F)][BAr′₄] (5a), which has been isolated and characterized by X-ray diffraction.

Full text of DOI:10.1021/ic700674c

Inorg. Chem. 2007, 46, 6958−6967
Coordinatively Unsaturated Semisandwich Complexes of Ruthenium
with Phosphinoamine Ligands and Related Species: A Complex
Containing (R,R)-1,2-Bis((diisopropylphosphino)amino)cyclohexane in a
New Coordination Form
K ′,N-η
3P,P 2-P,N
M. Dolores Palacios,† M. Carmen Puerta,† Pedro Valerga,*,† Agust´ı Lledo´s,‡ and Edouard Veilly‡
Departamento de Ciencia de Materiales e Ingenier´ıa Metalu´rgica y Qu´ımica Inorga´nica, Facultad
de Ciencias, UniVersidad de Ca´diz, 11510 Puerto Real, Ca´diz, Spain, and Departament de
Qu´ımica, Edifici Cn, UniVersitat Auto`noma de Barcelona, 08193 Bellaterra, Barcelona, Spain
Received April 9, 2007
The syntheses of the chloro complexes [Ru(
η
5-C5R5)Cl(L)] (R
phosphinoamine ligand) (1a
5-C5Me5)RuCl
}4 with the corresponding phosphinoamine
)
H, Me; L
)
−d) have
been carried out by reaction of [(
η
5-C5H5)RuCl(PPh3)2] or
{(η
(R,R)-1,2-bis((diisopropylphosphino)amino)cyclohexane), R,R-dippach, or 1,2-bis(((diisopropylphosphino)amino)ethane),
dippae. The chloride abstraction reactions from these compounds lead to different products depending on the
starting chlorocomplex and the reaction conditions. Under argon atmosphere, chloride abstraction from [(
RuCl(R,R-dippach)] with NaBAr 4 yields the compound [( -(R,R)-dippach)][BAr 4] (2b) which exhibits
5-C5Me5)Ru( 3P,P
a three-membered ring Ru P by a new coordination form of this phosphinoamine. However, under the same
conditions the reaction starting from [(
5-C5Me5)RuCl(dippae)] yields the unsaturated 16 electron complex [(η5
C5Me5)Ru(dippae)][BAr 4] (2d). The bonding modes of R,R-dippach and dippae ligands have been analyzed by
DFT calculations. The possibility of tridentate P,N,P-coordination of the phosphinoamide ligand to a fragment [(η5
C5Me5)Ru]+ is always present, but only the presence of a cyclohexane unit in the ligand framework converts this
bonding mode in a more favorable option than the usual P,P-coordination. Dinitrogen [(
5-C5R5)Ru(N2)(L)][BAr
(3a d) and dioxygen complexes [(
5-C5H5)Ru(O2)(R,R-dippach)][BPh4] (4a) and [( 5-C5Me5)Ru(O2)(L)][BPh4] (4b,d)
η
5-C5Me5)-
′
η
κ
′
′
−N−
η
-
′
-
η
′ ]
4
−
η
η
have been prepared by chloride abstraction under dinitrogen or dioxygen atmosphere, respectively. The presence
of 16 electron [(
η
5-C5H5)Ru(R,R-dippach)]+ species in fluorobenzene solutions of the corresponding dinitrogen or
-
dioxygen complexes in conjunction with the presence of [BAr 4
′
]
gave in some cases a small fraction of [Ru(η5
-
C5H5)(
η
6-C6H5F)][BAr
′
4] (5a), which has been isolated and characterized by X-ray diffraction.
Introduction
neous catalysis.5-10 In particular bis(phosphino)diamines
prepared from enantiopures 1,2-diamines have been used like
auxiliary ligands in applications of organometallic catalysis
for stereoselective organic transformations, like asymmetric
hydrogenation reactions,11-13 asymmetric hydroboration,14
Diels-Alder catalysis,15 etc.
Polydentate ligands containing phosphorus and nitrogen
atoms have been widely used to obtain chelate complexes
in coordination chemistry1-4 and in relation with homoge-
* To whom correspondence should be addressed. E-mail: pedro.valerga@
uca.es. Phone: +34 956 016340. Fax: +34 956 016288.
† Universidad de Ca´diz.
‡ Universitat Auto`noma de Barcelona.
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6958 Inorganic Chemistry, Vol. 46, No. 17, 2007
10.1021/ic700674c CCC: $37.00
© 2007 American Chemical Society
Published on Web 07/27/2007

Complexes of Ruthenium with Phosphinoamine Ligands
Scheme 1
Scheme 2
Whereas the donor character and basicity of the phosphi-
noamine strengthen when only one or two dialkylamine
ligands are bonded to the phosphorus, the coordination of
three groups -NR2 to the phosphorus causes a decrease in
donor properties. X-ray studies of tris(alkylamino)phosphines
and complexes containing these ligands show two short bond
lengths P-N in the same plane and a third one longer with
a nitrogen atom out of the plane. This fact suggested that
only two nitrogen atoms can efficiently donate electron pairs
to the phosphorus atom, while the last substituent -NR2 acts
like an electronegative group decreasing the phosphorus
donor properties (Scheme 2).34
We have recently reported compounds containing non-
chiral dippae (1,2-bis(((diisopropylphosphino)amino)ethane))
or chiral R,R-dippach phosphinoamine (R,R-1,2-bis((diiso-
propylphosphino)amino)cyclohexane) and the ligand hydri-
dotris(pyrazolyl)borate) (Tp) {TpRuCl(L′)} (L′ ) R,R-
dippach, dippae).4 Our study was focussed in the synthesis
and characterization of hydride and related compounds and
their behavior in protonation reactions with strong and weak
acids. This work deals with the study of semisandwich
ruthenium systems [Ru(η5-C5R5)Cl(L)] containing cyclopen-
tadienyl, Cp, or pentamethylcyclopentadienyl, Cp*, and the
phosphinoamine ligand R,R-dippach or dippae in relation
with halide abstraction reactions under argon, dinitrogen, or
air.
A variety of rhodium,16-19 palladium,20 and platinum21-22
complexes containing these ligands have been synthesized
and characterized. Nevertheless, the analogous ruthenium
complexes are still scarce, in spite of their increasingly
interest during last years.23-25 Recently, Morris and co-
workers have described a series of ruthenium complexes with
the diphosphine-diamine system which catalyzes asym-
metric hydrogenation reactions of ketones,26 Michael addition
reactions,27 etc. Chan et al. have reported that palladium
complexes containing phosphinoamine are catalysts to the
enantioselective allylic alkylation28 and rhodium complexes
are active in catalytic hydrogenation reactions.29
The electronic properties of phosphines range from very
strong σ-donors alkylphosphines to phosphines with π-ac-
ceptor character like the fluoroalkylphosphines. A great
variety of species with phosphorus and nitrogen atoms have
been described displaying a range of electronic and steric
properties. The basicity and the electronic character of the
resultant phosphinoamine moieties can be modulated by
means of the fragments NR bounded to the phosphorus. For
instance, phosphinoamines which were synthesized starting
from different chlorophosphines and pyrrolidine (Scheme 1)
present even stronger σ-donor character than some trialkylphos-
phines.30-33
(11) Cucciolito, M. E.; D’Amora, A.; Vitagliano, A. Organometallics 2005,
24, 3359.
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2005, 16, 2063.
Results and Discussion
The thermal displacement of PPh3 from [(η5-C5H5)RuCl-
(PPh3)2] by either R,R-dippach or dippae in refluxing toluene
leads to the corresponding chloro-complexes [(η5-C5H5)-
RuCl(R,R-dippach)] (1a) and [(η5-C5H5)RuCl(dippae)] (1c)
(Scheme 3). Both 1a,c are obtained as microcrystalline
orange solids in high yields. In the 1H NMR spectrum of 1c
the phosphinoamine ligand shows signals corresponding to
the methyl groups between 0.8 and 1.5 ppm and two
multiplets due to the CH groups at 2.13 and 2.26 ppm.
Whereas the proton resonance of NH groups appears at 1.98
ppm, at 4.60 ppm one singlet due to the Cp hydrogens is
observed. At temperatures above 213 K one singlet at 118.0
ppm is observed in the 31P{1H} NMR spectrum. However,
at 193 K the ethylene chain movement is slow enough to
observe two doublets because both phosphorus became
nonequivalent. More complex spectra are recorded for 1a
because of the presence of the chiral phosphinoamine ligand.
(13) Li, X.; Jia, X.; Xu, L.; Kok, S. H. L.; Yip, C. W.; Chan, A. S. C. AdV.
Synth. Catal. 2005, 347, 1904.
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F.; Sanchez, F.; Martinez, S.; Cativiela, C.; Lopez-Ram, de Viu, M.
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Schmutzler, R. Z. Anorg. Allg. Chem. 2000, 626, 1763.
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A.; Petrovskii, P. V.; Lysenko, K. A.; Gavrilov, K. N. Russ. J. Coord.
Chem. 2001, 27, 591.
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(19) Powell, J.; May, C. J. J. Am. Chem. Soc. 1982, 104, 2636.
(20) Zhang, F. Y.; Pai, C. C.; Chan, A. S. C. J. Am. Chem. Soc. 1998,
120, 5808.
(21) Zijp, E. J.; van der Vlugt, J. I.; Tooke, D. M.; Spek, A. L.; Vogt, D.
Dalton Trans. 2005, 512.
(22) Balakrishna, M. S.; Walawalker, M. G. J. Organomet. Chem. 2001,
628, 76.
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20, 1047.
(24) Balakrishna, M. S.; Abhyankar, R. M.; Mague, J. T. J. Chem. Soc.,
Dalton Trans. 1999, 1407.
(25) Faller, J.; W.; Fontaine, P. P. Organometallics 2005, 24, 4132.
(26) Guo, R.; Lough, A. J.; Morris, R. H.; Song, D. Organometallics 2004,
23, 5524.
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A. M. Z.; Woollins, J. D. Inorg. Chem. Commun. 2004, 7, 201.
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Chem. Soc., Dalton Trans. 2002, 1093.
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(28) Chen, X.; Guo, R.; Li, Y.; Chen, G.; Yeung, C. H.; Chan, A. S. C.
Tetrahedron: Asymmetry 2004, 15, 213.
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2001, 12, 2337.
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Inorganic Chemistry, Vol. 46, No. 17, 2007 6959

Palacios et al.
Scheme 3
In this case the phosphorus atoms are nonequivalent even at
room temperature and the 31P{1H} NMR spectrum shows
two doublets at 112.6 and 113.8 ppm with one coupling
constant of 51 Hz. Furthermore, a higher number of signals
in the 1H and 13C{1H} NMR spectra is observed in relation
with those of compound 1c.
Figure 1. ORTEP drawing (50% thermal ellipsoids) of the cation [(η5-
C5Me5)Ru(R,R-dippach)]+ in 2b. Hydrogen atoms have been omitted.
Selected bond lengths (Å) and angles (deg) with estimated standard
deviations in parentheses: Ru(1)-P(1), 2.3211(12); Ru(1)-P(2), 2.2780-
(12); Ru(1)-N(2), 2.260(4); P(2)-N(2), 1.734(3); P(1)-N(1), 1.696(4);
P(2)-C(23), 1.856(5); P(1)-C(26), 1.840(4); N(1)-C(17), 1.467(5); N(2)-
C(18), 1.518(5); P(1)-Ru(1)-P(2), 93.19(5); P(1)-Ru(1)-N(2), 90.46-
(9); P(2)-Ru(1)-N(2), 44.93(8); Ru(1)-P(2)-N(2), 66.97(14); Ru(1)-
N(2)-P(2), 68.09(12); Ru(1)-P(1)-N(1), 108.85(13); P(2)-N(2)-C(18),
126.2(3); Ru(1)-N(2)-C(18), 128.7(3); Ru(1)-N(2)-H(2), 114(2).
The method used to obtain the Cp* analogous has been
the reaction between {(η5-C5Me5)RuCl}4 and R,R-dippach
or dippae in petroleum ether, yielding the complexes [(η5-
C5Me5)RuCl(R,R-dippach)] (1b) and [(η5-C5Me5)RuCl-
1
(dippae)] (1d). H NMR spectra of both complexes are
distance Ru(1)-N(2) of 2.260(4) Å is slightly longer than
the values observed for the complex [(η5-C5Me5)Ru(Me2-
NCH2CH2NMe2)]+ (2.180(6) and 2.183(7) Å),36 although
closer to the values 2.235(5) and 2.262(5) Å, reported
for the complex [(η5-C5Me5)Ru(Me2NCH2CH2NMe2)(Nt
CCH3)]+.37 The Ru-P bond distances on both sides of the
ligand Ru(1)-P(2) display a slightly shorter value, 2.2780(12)
Å, than for Ru(1)-P(1), 2.3211(12) Å. The additional
electronic donation to the metal from nitrogen enhances the
basicity on the metal center increasing the back-donation over
the phosphorus atom in the three-ring metallacycle. This fact
strenghts the bond Ru(1)-P(2) in relation to Ru(1)-P(1)
and consequently elongates the bond distance P(2)-N(2) to
1.734(3) Å, in comparison with the value of 1.696(4) Å for
P(1)-N(1). Steric effects derived from the trigonal Ru-P-N
geometry contribute to fix the limits of values for this set of
angles and distances.
The NMR spectra of 2b at different temperatures are
consistent with the described structure. At room temperature,
the 1H NMR spectrum shows one broad signal to Cp* protons
while in the 31P{1H} spectrum a broad singlet appears at 84
ppm. At lower temperatures (210-190 K), the 31P{1H} NMR
resonance decoaleces to two doublets at 71 and 95 ppm
(Figure 2). The difference between both chemical shifts
agrees with the significative differences in Ru-P bonding.
However, a dynamic process renders the phosphorus atoms
equivalents at room temperature. This process can be
described as an equilibrium through the intermediate 16
electron complex, and it involves alternative breaking and
formation of Ru-N bonds (Scheme 4). NMR line-shape
similar to those previously discussed of compounds 1a,c
except by the presence of -CH3 groups. In the same way,
one singlet for 1d and two doublets for 1c have been
observed in the corresponding 31P{1H} NMR spectra.
Chloride Abstraction under Argon Atmosphere. In an
effort to obtain 16 electron species or the substitution by
dinitrogen or dioxygen molecules chloride abstraction reac-
tions under different conditions have been investigated.
Under argon we expected the formation of unsaturated
complexes. However, the chloride abstraction from the
compounds 1b,d under argon with NaBAr′4 leads to very
different products. In the case of 1b, instead of a deep colored
material, an orange solution was obtained. A first crop of
orange microcrystals needed to be recrystallized affording
suitable crystals for X-ray diffraction analysis. An ORTEP
view of the cation [(η5-C5Me5)Ru (R,R-dippach)]+ in 2b is
shown in Figure 1. The chelation of the diphosphine ligand
is reinforced by means of a novel κ3P,P′,N-η2-P,N coordina-
tion in which an amine nitrogen is bounded to the metal in
addition to the two phosphorus. A relative stabilization is
reached upon the formation of two chelate rings, namely one
three-membered and other six-membered metallacycles. We
have found in the literature only a related structure for the
cobalt complex [Co{κ3P,P′,N-(Ph2PNP(Ph)2NPPh2}{κ2P,P′-
(Ph2PNP(Ph)2NPPh2}] described by Ellermann et al.35 But
in that case the nitrogen linked to the cobalt has a clear iminic
character.
One side of the R,R-dippach ligand adopts a η2-P,N
coordination with angle P(2)-Ru(1)-N(2) of 44.93(8)° and
angles Ru(1)-P(2)-N(2) and Ru(1)-N(2)-P(2) of 66.97-
(14) and 68.09(12)°, respectively. As expected the bond
(36) Gemel, C.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics
1997, 16, 5601.
(35) Ellermann, J.; Sutter, J.; Knoch, F. A.; Moll, M. Angew. Chem., Int.
Ed. Engl. 1993, 32, 700.
(37) Gemel, C.; LaPensee, A.; Mauthner, K.; Mereiter, K.; Schmid, R.;
Kirchner, K. Monatsh. Chem. 1997, 128, 1189.
6960 Inorganic Chemistry, Vol. 46, No. 17, 2007

Complexes of Ruthenium with Phosphinoamine Ligands
complex with N-Ru interaction as in the case of 2b already
discussed. Studies by VT 31P{1H} NMR spectroscopy show
a singlet at 96.4 ppm at room temperature. At lower
temperatures this resonance broadens and gradually coa-
lesces. In the range 213-193 K no signal has been observed
in this region. The resonance decoalescence has not been
observed even at the lowest temperature. The fluxional
process changing chelate ring conformation is very fast. In
the case of this unsaturated complex containing dippae with
a flexible ethylene chain, temperatures lower than 193 K
would be necessary to reduce movement and to observe two
nonequivalent phosphorus atoms.
Computational Study of the Bonding Modes of R,R-
dippach and dippae Ligands. One striking feature of the
complexes obtained by chloride abstraction under argon
atmosphere from [(η5-C5Me5)RuClL] (L ) phospinoamine
ligand) is the very different bonding mode adopted by the
phospinoamine ligand in 2b (L ) (R,R)-dippach) and 2d (L
) dippae). We have performed a computational study to
understand this behavior and to gain an insight into the
bonding properties of phospinoamine ligands. The first point
analyzed has been to check if both the usual bidentate P,P
coordination and the unprecedented tridentate P,N,P are
possible with both ligands. To this aim the structure of the
2b,d complexes have been fully optimized with either P,P
(2b-PP, 2c-PP) and P,N,P (2b-PNP, 2c-PNP) coordination
of the phosphinoamine ligand. Both minima have been found
for the two complexes. However the relative stability of both
minima is very different depending on the phosphinoamine
ligand. With the dippae ligand the 16 electron isomer
entailing the usual P,P coordination is found 7.1 kcal‚mol-1
more stable than the tridentate one. On the contrary, with
the R,R-dippach ligand the 18 electron isomer involving the
two chelate rings lies 12.2 kcal‚mol-1 below the unsaturated
one. We have also checked the possibility of a high-spin
state for the 16 electron complexes. The singlet state is
favored for both ligands, with a very similar singlet-triplet
gap (10.1 and 10.2 kcal‚mol-1 for the R,R-dippach and dippae
complexes, respectively). The computed stabilities fully agree
with the experimental characterization of 2b,c as tridentate
18 electron compound and bidentate diamagnetic 16 electron
compound, respectively.
Figure 2. VT 31P{1H} NMR spectra (161.89 MHz) in CD2Cl2 of 2b.
Scheme 4
fitting allows the estimation of a value of 8.4((0.2)
kcal‚mol-1 for the free enthalpy of activation, ∆Hq, and
-9((0.9) cal‚mol-1‚K-1 for the entropy of activation, ∆Sq.
On the contrary, 1H NMR spectra using the N-H signal did
not allow a similar study. N-H resonances appear nearest
to those corresponding to isopropyl and cyclohexyl C-H.
All these signals broaden and slightly shift at lower tem-
peratures.
The solutions of 2b were contaminated by the presence
of small amounts of dinitrogen complex [(η5-C5Me5)Ru(N2)-
(R,R-dippach)]+. Even using a higher purity argon and
greatest care in doing the experiments, it was detected in
the 31P{1H}NMR spectra at all measured temperatures by
two doublets signals at 85 and 94 ppm. In a posterior part
of this work, the compound 3b, containing the dinitrogen
complex cation, will be discussed.
Contrary to 1b, the treatment of [(η5-C5Me5)RuCl(dippae)]
(1d) with NaBAr′4 allows the isolation of a blue crystalline
16 electron compound [(η5-C5Me5)Ru(dippae)][BAr′4] (2d).
We have studied by X-ray crystallography different crystals
from samples independently obtained. In all the cases the
analyses of data collections allows finding a structure that
reveals basically an unsaturated 16 electron skeleton for the
cation. Unfortunately, crystal quality, some positional dis-
order, and other factors did not allow a refinement good
enough to be published. Nevertheless, the 16 electron nature
of this complex has been confirmed by NMR spectroscopy.
In the 13C{1H) NMR spectrum the quaternary Cp* carbons
displays a resonance at 66.3 ppm in agreement with other
16 electron cationic complexes of ruthenium, Cp*RuLn.38-39
We do not discard the presence of a small proportion of a
We have also checked the possible existence of the P,P-
and P,N,P-coordinated minima with a [(η5-C5H5)Ru]+ metal
fragment. Indeed both minima are also found for both dippae
and R,R-dippach ligands, proving that the possibility of a
tridentate P,N,P coordination, with formation of two chelate
rings, also exists with the amino ethane ligand. This
alternative could be always present with the phosphinoamine
ligands when coordinated to highly unsaturated metal frag-
ments. The energy ordering of the P,P- and P,N,P-
coordinated isomers of [(η5-C5H5)RuL]+ complexes is very
similar to that found for those of the [(η5-C5Me5)RuL]+
compounds. With the Cp ligand the 16-electron bidentate
complex is found 5.4 kcal‚mol-1 more stable than the
(38) Halikhedkar, A.; Jime´nez-Tenorio, M.; Puerta, M. C.; Valerga, P.;
Sapunov, V. N.; Schmid, R.; Kirchner, K.; Mereiter, K. Organome-
tallics 2002, 21, 5334.
(39) Gemel, C.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics
1997, 16, 5601.
Inorganic Chemistry, Vol. 46, No. 17, 2007 6961

Palacios et al.
Scheme 5. Structural Changes in Passing from the P,P to the P,N,P
Coordinationa
a Arrows indicate lengthening (r f) or shortening (f r) of the bond.
considerably shortened, with the bond distance corresponding
to the phosphorus atom participating in the three-member
ring (P2) being the shortest one. Furthermore a notable
difference is introduced in the two sets of P-N and N-C
bond distances depending on the participation of the N in
the three-member ring: distances involving the nitrogen atom
in the short ring (N2) are longer than those of N1.
These changes can be explained taking into account the
participation of the N lone pair in the Ru-N bond of the
P,N,P isomers. In the P,P isomer the N lone pair is partially
delocalized in a PdN bond, but it can no longer be
delocalized when coordinated to the ruthenium. Accordingly
the P-N distance lengthens from 1.719 Å in 2b-PP to 1.787
Å in 2b-PNP. A similar change is found in the 2c isomers.
Another structural feature to be pointed out in the R,R-
dippach complexes is the different conformation adopted by
the cyclohexane in the P,P and P,N,P coordination modes,
which is apparent in Figure 3. The X-ray structure of 2b
shows a chair cyclohexane conformation. This is also the
most stable conformation for the P,N,P coordination found
in the computational study. We have also optimized a 2b-
PNP structure with a twist-boat cyclohexane conformation,
but it lies 13.9 kcal‚mol-1 above that with the chair
conformation. On the contrary in the structure with the P,P
coordination the cyclohexane adopts a twist-boat conforma-
tion. Indeed with a twist-boat conformation of cyclohexane
the isomer with P,P-coordinated (R,R-dippach) is 1.7
kcal‚mol-1 more stable than the P,N,P one. We have also
tried to obtain a 16 electron compound with the chair
cyclohexane conformation, but all the attempts ended up with
a P,N,P coordination of the R,R-dippach ligand. In this ligand
the chair conformation places a nitrogen atom in the vicinity
of the unsaturated ruthenium atom, facilitating its coordina-
tion to fulfill the 18-electron configuration. This is not the
case when the cyclohexane has a twist-boat conformation
which places the two nitrogen atom about 3.7 Å far from
the metal. The change on the R,R-dippach from the P,N,P
to the P,P coordination mode should imply a conformational
change on the cyclohexane unit of the ligand from the most
stable chair conformation to the less stable twist-boat one.
This factor would enhance the stability of the P,N,P
coordination to the [(η5-C5Me5)Ru]+ fragment.
Figure 3. Optimized structures of the P,N,P-coordinated (left) and P,P-
coordinated (right) isomers of [(η5-C5Me5)Ru(R,R-dippach)]+ (2b) and [(η5-
C5Me5)Ru(dippae)]+ (2c). Hydrogen atoms have been omitted for clarity.
Table 1. Selected Geometrical Parameters (Å and deg) of the
Optimized Structures of the P,N,P- and P,P-Coordinated Isomers of
2b,ca
[[(η5-C5Me5)Ru(R,R-dippach)]+ [[(η5-C5Me5)Ru(dippae)]+
param
P,N,P
P,P
P,N,P
P,P
Ru-P1
2.403
2.369
2.634
1.787
1.742
1.479
1.497
1.537
2.528
2.510
3.702
1.719
1.727
1.461
1.464
1.574
2.393
2.350
2.304
1.796
1.729
1.465
1.484
1.527
2.518
2.479
3.585
1.714
1.739
1.466
1.458
1.526
Ru-P2
Ru-N2
P2-N2
P1-N1
N1-C17
N2-C18
C17-C18
P1-Ru-P2
P1-Ru-N2
P2-Ru-N2
Ru-P2-N2
Ru-N2-P2
Ru-P1-N1
P2-N2-C18
Ru-N2-C18
93.0
88.5
44.4
67.7
101.8
79.5
23.5
121.0
35.3
120.5
123.9
88.6
95.6
86.2
45.4
65.9
96.7
72.4
25.3
116.4
38.4
118.5
123.2
90.1
67.9
68.7
108.1
126.6
130.5
114.6
132.1
124.3
a For the atom numbering, see Figure 1 and Scheme 5.
tridentate 18 electron isomer for L ) dippae. On the contrary
with L ) R,R-dippach the 18 electron isomer with two
chelate rings is found 14.0 kcal‚mol-1 below the unsaturated
one. Clearly the stability of the 16 and 18 electron isomers
is governed by the nature of the phosphinoamine ligand.
The optimized geometries of the P,P and P,N,P isomers
of [(η5-C5Me5)Ru(R,R-dippach)]+ and [(η5-C5Me5)Ru(dippae)]+
are depicted in Figure 3. Selected geometrical parameters
are collected in Table 1. In a comparison of the optimized
structure of 2b-PNP with the X-ray characterized of 2b
(Figure 1), a good agreement can be observed. From the data
in Table 1 it can be appreciated that in addition to the
expected shortening of the Ru-N2 distance changing from
the P,P to the P,N,P coordination involves remarkable
variations in other distances of the chelating ring. These
changes are schematized in Scheme 5. The Ru-P bonds are
To go further in the comparison of the bonding properties
of the R,R-dippach and dippae ligands, we have performed
an energy analysis of the transition metal-phosphinoamine
coordination using a theoretical approach that we have
already employed for investigating the coordination modes
of multidentate ligands.40,41 In this approach we consider the
(40) Lledo´s, A.; Carbo´, J.; Navarro, R.; Urriolabeitia, E. P. Inorg. Chim.
Acta 2004, 357, 1444.
6962 Inorganic Chemistry, Vol. 46, No. 17, 2007

Complexes of Ruthenium with Phosphinoamine Ligands
Table 2. Energy Decomposition (kcal‚mol-1) for the Bonding of
Phosphinoamine Ligands to [(η5-C5Me5)Ru]+
Table 3. Relative Energies (kcal‚mol-1) of the P,N,P Isomers of
[(η5-C5Me5)Ru(R,R-dRpach)]+ and [(η5-C5Me5)Ru(dRpae)]+ Complexes
i
(R ) H, Me, Et, Pr)a
[[(η5-C5Me5)Ru(R,R-dippach)]+ [[(η5-C5Me5)Ru(dippae)]+
R
[[(η5-C5Me5)Ru(R,R-dRpach)]+
[(η5-C5Me5)Ru(dRpae)]+
param
P,N,P
P,P
P,N,P
P,P
H
Me
Et
-6.9
-8.5
-10.8
-12.2
+1.9
+5.5
+6.1
+7.1
∆Edistortion
∆Einteraction
∆EbondingL
16.4
-101.8
-85.4
10.7
-83.9
-73.2
40.5
-104.1
-63.6
15.5
-86.2
-70.1
iPr
a The energy of the corresponding P,P-coordinated isomer has been taken
as a zero.
formation of [(η5-C5Me5)RuL]+ (L ) R,R-dippach, dippae)
in the two coordination modes from the [(η5-C5Me5)Ru]+
fragment and the free L ligand. The ∆E value of this reaction
is the bonding energy of the phosphinoamine ligand to the
[(η5-C5Me5)RuL]+ fragment (∆EbondingL). This ∆E can be
decomposed into two terms: one accounting for the distortion
of L from its isolated optimized geometry to the final
geometry in the complex (∆Edistortion); the other one for the
interaction of the distorted complex with the metal fragment
to give the complex (∆Einteraction). The energy values arising
from this energy decomposition are gathered in Table 2.
The decomposition of the bonding energy for the two
ligands in the two coordination modes clearly shows the
factors determining the experimental behavior of R,R-dippach
and dippae with the [(η5-C5Me5)Ru]+ fragment. The interac-
tion energies are very similar for both ligands, the bonding
of the N lone pair to the metal always entailing an energy
gain of about 18 kcal‚mol-1. On the contrary, the distortion
terms are very different. Changing from the P,P coordination
to the P,N,P one implies a weak distortion of the R,R-dippach
ligand (5.7 kcal‚mol-1) but a severe distortion of the dippae
one (25 kcal‚mol-1). For R,R-dippach the interaction com-
ponent compensates the destabilization introduced by the
ligand distortion, favoring a tridentate, 18-electron structure.
This is not the case with dippae, the greater distortion energy
preventing the adoption of the P,N,P coordination. Clearly
the presence in the backbone of the phosphinoamine ligand
of a cyclohexane makes the complex much more suitable to
attain an 18-electron configuration by means of an additional
Ru-N bond with only a slight distortion. The cyclohexane
part of the R,R-dippach ligand allows diminishing the
distortion energy mainly for the tridentate coordination. The
chair conformation of the cyclohexane lays out one of the
two nitrogen atoms well disposed to interact with the
ruthenium atom.
hexane ligands (L ) dRpach), whatever the R substituents
in the phosphine. The contrary happens with phosphinoamine
ethane ligands (L ) dRpae). However, the energy difference
between the 16 and 18 electron compounds is considerably
affected by the phosphine substituents. The stability trend
is opposite depending on the presence of the ethane or the
cyclohexane unit on the ligand framework. With ethane
(dRpae ligands) the stability of the 16 electron compound
i
increases in the order H < Me < Et < Pr. The effect is
particularly important when passing from R ) H to R )
Me. This is the expected behavior in the stability of
unsaturated complexes when increasing the donating capabil-
ity of the phosphine ligand. On the contrary, phospine
substitution in the cyclohexane complexes (dRpach ligands)
causes an increased stabilization of the P,N,P isomers. Steric
effects and the distortion component of the bonding are
responsible for this trend. The phosphinoamine ligands with
a cyclohexane are much more suitable for adapting the chain
to the constraints imposed by the P,N,P coordination. This
is reflected in the values of the PRuP angles in both isomers.
Whereas this angle increases notably in the P,P-coordinated
structures of [(η5-C5Me5)Ru(R,R-dRpach)]+ complexes (R
i
) H, 86.5°; R ) Me ) 90.4°; R ) Et, 94.1°; R ) Pr,
101.8°), it only increases 4° in the P,N,P ones (R ) H, 88.6°;
i
R ) Me, 91.2°; R ) Et, 91.8°; R ) Pr, 93.0°)
Chloride Abstraction under Dinitrogen Atmosphere.
When compounds 1a-d are treated by a similar procedure
with NaBAr′4 under dinitrogen, they yield the corresponding
products [(η5-C5R5)Ru(N2)(L)][BAr′4] (3a-d). The IR spec-
tra of these dinitrogen complexes show the characteristic
strong ν(N-N) peak at frequency ranging from 2142 cm-1
for 3b to 2201 cm-1 for 3d. In the 31P{1H} NMR spectra of
the R,R-dippach derivatives, two doublets at 110.6 and 112.5
ppm (for 3a) or at 99.7 and 102.0 ppm (for 3b) are consistent
with the nonequivalence of the two phosphorus. Contrary,
in the case of dippae derivatives 3c,d only a singlet appears
at room temperature. In a similar way also 1H and 31C{1H}
spectra are more complex in the case of 3a or 3b, containing
R,R-dippach, than in the case of 3c or 3d.
The X-ray crystal structure of [(η5-C5H5)Ru(N2)(R,R-
dippach)][BAr′4] (3a) has been obtained, and a cation
complex drawing is presented in Figure 4. The “three-legged
piano stool” structure containing a end-on bounded dinitrogen
ligand closely resembles that of the related complex cation
[(η5-C5H5)Ru(N2)(dippe)]+.42 The distances Ru(1)-N(1) and
Ru(2)-N(5) are 1.959(5) and 1.913(6) Å, similar to that
The last point addressed in the computational study has
been the influence of the phospine substituents on the relative
stabilities of the 16 and 18 electrons structures. We have
optimized the structures of the P,N,P- and P,P-coordinated
+
isomers of [Cp*Ru(R,R-dRpach)]+ and [Cp*Ru(dRpae)]
complexes, with R ) H, Me, and Et. The relative energies
of the 18 electron tridentate isomers with respect the
corresponding 16 electrons bidentate ones are given in Table
3.
Values in Table 3 show that the change on the phosphine
substituents does not modify the energy ordering of both
isomers. The P,N,P-coordinated structure is always found
more stable than the P,P-one with phosphinoamine cyclo-
(41) Falvelo, L. R.; Gine´s, J. C.; Carbo´, J.; Lledo´s, A.; Navarro, R.; Soler,
(42) Halikhedkar, A.; Jime´nez-Tenorio, M.; Puerta, M. C.; Valerga, P.;
T.; Urriolabeitia, E. P. Inorg. Chem. 2006, 45, 6803.
Mereiter, K. Organometallics 2002, 21, 628.
Inorganic Chemistry, Vol. 46, No. 17, 2007 6963

Palacios et al.
Figure 5. ORTEP drawing (50% thermal ellipsoids) of complex cation
[(η5-C5Me5)Ru(η2-O2)(dippae)]+ in 4d′. Hydrogen atoms have been omitted.
Selected bond lengths (Å) and angles (deg) with estimated standard
deviations in parentheses: Ru(1)-P(1), 2.3972(13); Ru(1)-P(2), 2.3868-
(16); Ru(1)-O(1), 2.026(3); Ru(1)-O(2), 2.032(3); O(1)-O(2), 1.399(4);
P(1)-Ru(1)-P(1), 88.03(5); O(1)-Ru(1)-O(2), 40.33(11); O(1)-O(2)-
Ru(1), 69.62(16); O(2)-O(1)-Ru(1), 70.05(16).
Figure 4. ORTEP drawing (50% thermal ellipsoids) of one complex cation
[(η5-C5Me5)Ru(N2)(R,R-dippach)]+ in 3a. Hydrogen atoms have been
omitted. Selected bond lengths (Å) and angles (deg) with estimated standard
deviations in parentheses follow. Cation 1: Ru(1)-P(1), 2.2448(17); Ru-
(1)-P(2), 2.4148(17); Ru(1)-N(1), 1.959(5); N(1)-N(2), 1.096(7); P(1)-
N(3), 1.678(5); P(2)-N(4), 1.614(5); P(1)-Ru(1)-P(2), 95.02(6); P(1)-
Ru(1)-N(1), 91.90(15); P(2)-Ru(1)-N(1), 90.83(15); Ru(1)-N(1)-N(2),
175.2(5). Cation 2: Ru(2)-P(3), 2.4142(19); Ru(2)-P(4), 2.2812(18); Ru-
(2)-N(5), 1.912(6); N(5)-N(6), 1.074(9); P(3)-N(7), 1.595(5); P(4)-N(8),
1.616(5); P(3)-Ru(2)-P(4), 92.21(7); P(3)-Ru(2)-N(5), 92.4(2); P(4)-
Ru(2)-N(5), 96.37(18); Ru(2)-N(5)-N(6), 173.6(6).
[BPh4] that we have already reported43 and can be also
formed during the reactions with other small molecules like
H2, N2, etc. In this manner [(η5-C5Me5)Ru(O2)(dippae)]-
[B{C6H3(CF3)2}4] (4d′) crystallized from solutions of 3d even
when very small amounts of dioxygen were present. The
structure of 4d′ has been determined by X-ray single-crystal
diffraction, and a cation drawing is presented in Figure 5.
The chloride complex [(η5-C5Me5)RuCl(R,R-dippach)]
seems to be even more reactive than [(η5-C5Me5)RuCl-
(dippae)] to trap very small amounts of dioxygen present in
solution. On the other hand, the dioxygen complex [(η5-
C5H5)Ru(O2)(R,R-dippach)][BPh4] (4a) represents the first
isolated dioxygen complex containing the fragment {CpRu}.
In a previous work we have reported the decomposition of
the dinitrogen complex [(η5-C5H5)Ru(N2)(dippe)][BPh4]43 to
the already well-known final product [(η5-C5H5)Ru(η6-C6H5-
BPh3)]. The formation of this sandwich ruthenium complex
has been proposed to go through an intermediary dioxygen
complex. The complex [(η5-C5H5)Ru(O2)(R,R-dippach)]-
[BPh4] (4a) is a stable yellow compound in the solid state.
Nevertheless, when a solution of 4a in CDCl3 was followed
by NMR during 24 h the dioxygen complex transferring
dioxygen to the phosphinoamine ligand or by an alternative
mechanism leads also to the sandwich complex [(η5-C5H5)-
Ru(η6-C6H5BPh3)].44 In the presence of [BAr′4]- instead of
[BPh4]- even the poorly coordinative fluorobenzene solvent
molecule can been “trapped”. Thus, small amounts of the
novel sandwich complex [(η5-C5Me5)Ru(η6-C6H5F)][BAr′4]
(5a) are obtained in the course of chloride abstraction
reactions to obtain dinitrogen or dioxygen complexes. A
small fraction of colorless crystals of 5a was obtained from
the solution in which [(η5-C5H5)Ru(N2)(R,R-dippach)][BAr′4]
found for the complex containing dippe, 1.961(3) Å. The
Ru(1)-N(1)-N(2) and Ru(2)-N(5)-N(6) angles of 173.7(6)
and 175.3(5)° indicate an almost linear Ru-N2 assembly,
and they compare well to the value of 175.8(4)° in the related
dippe complex. Dinitrogen distances N(1)-N(2), 1.094(7)
Å, and N(5)-N(6), 1.076(8) Å, are in the typical range found
in other dinitrogen ruthenium complexes indicating a slight
activation of the N2 ligand. The bond lengths Ru(1)-P(1),
2.2448(17) Å, and Ru(1)-P(2), 2.4148(17) Å, in the first
cation, and Ru(2)-P(3), 2.4142(19) Å, and Ru(2)-P(4),
2.2812(18) Å, in the second independent cation, were found
nonequivalent in the crystal. A theoretical calculation fully
optimizing the geometry of the cation [(η5-C5H5)Ru(N2)(R,R-
dippach)]+ gives an N2 coordination in agreement with that
in the crystal structure (Ru-N ) 1.984 Å, N-N ) 1.119
Å, and P-Ru-N angles of 88.0 and 92.9°) but with very
similar Ru-P bond distances (2.415 and 2.409 Å). Optimiz-
ing the structure of the cation with one shorter Ru-P
distance, fixed at the crystal value (2.245 Å), gives an energy
only 2.7 kcal/mol above the minimum. This energy can be
exceeded by the intermolecular interactions in solid state
which could be the origin of the difference in the Ru-P bond
distances.
Chloride Abstraction under Air. The isolation of di-
oxygen complexes [(η5-C5H5)Ru(O2)(R,R-dippach)][BPh4]
(4a), [(η5-C5Me5)Ru(O2)(R,R-dippach)][BPh4] (4b), and [(η5-
C5Me5)Ru(O2)(dippae)][BPh4] (4d) has been possible when
chloride abstraction is carried out under air. These complexes
have been characterized by elemental analysis and NMR
spectroscopy. They are similar to [(η5-C5Me5)Ru(O2)(dippe)]-
(43) de los Rios, I.; Jimenez Tenorio, M.; Padilla, J.; Puerta, M. C.; Valerga,
P. J. Chem. Soc., Dalton Trans. 1996, 377.
(44) de los Rios, I.; Jimenez Tenorio, M.; Padilla, J.; Puerta, M. C.; Valerga,
P. Organometallics 1996, 15, 4565.
6964 Inorganic Chemistry, Vol. 46, No. 17, 2007

Complexes of Ruthenium with Phosphinoamine Ligands
Experimental Section
All synthetic operations were performed under a dry argon
atmosphere, using conventional Schlenk techniques. Tetrahydro-
furan, diethyl ether, and petroleum ether (boiling point range 40-
60 °C) were distilled from the appropriate drying agents. Fluo-
robenzene was purchased from Aldrich and acetone (0.01% water
maximum) from SDS. All solvents were deoxygenated inmediately
45
before use. The complex {(η5-C5Me5)RuCl}4 as well as [Na-
BAr′4]46 was prepared according to reported procedures. The ligands
R,R-dippach and dippae were prepared by following suitable
adaptations of published procedures.23,47,48 IR spectra were recorded
in Nujol mulls on a Perkin-Elmer Spectrum 1000 spectrophotom-
eter. NMR spectra were taken on Varian Unity 400 MHz or Varian
Gemini 300 MHz equipment using the suitable deuterated solvent.
Chemical shifs are given in ppm from SiMe4 (1H and 13C{1H})
and 85% H3PO4 (31P{1H}). Microanalyses were performed on a
elemental analyzer model LECO CHNS-932 at the Servicio Central
de Ciencia y Tecnolog´ıa, Universidad de Ca´diz.
Figure 6. ORTEP drawing (50% thermal ellipsoids) of one cation [(η5-
C5Me5)Ru(FPh)]+ in 5a. Selected bond lengths (Å) with estimated standard
deviations in parentheses follow. Cation 1: Ru(1)-C(1b), 2.232(10); Ru-
(1)-C(2b), 2.194(10); Ru(1)-C(3b), 2.086(10); Ru(1)-C(4b), 2.057(10);
Ru(1)-C(5b), 2.150(9); Ru(1)-C(1a_2), 2.148(7); Ru(1)-C(2a_2), 2.191(7);
Ru(1)-C(3a_2), 2.274(8); Ru(1)-C(4a_2), 2.316(7); Ru(1)-C(5a_2), 2.276-
(6); Ru(1)-C(6a_2), 2.192(7); F(1a_2)-C(2a_2), 1.299(10). Cation 2: Ru-
(2)-C(7a), 2.201(12); Ru(2)-C(8a), 2.151(14); Ru(2)-C(9a), 2.070(12);
Ru(2)-C(10a), 2.073(9); Ru(2)-C(11a), 2.154(10); Ru(2)-C(7b_2), 2.183-
(8); Ru(2)-C(8b_2), 2.214(10); Ru(2)-C(9b_2), 2.282(8); Ru(2)-
C(10b_2), 2.318(6); Ru(2)-C(11b_2), 2.288(6); Ru(2)-C(12b_2), 2.220(6);
F(2b_2)-C(8b_2), 1.256(11).
[(η5-C5H5)RuCl(R,R-dippach)] (1a). To a solution of [(η5-
C5H5)RuCl(PPh3)2] (3 g, 4.0 mmol) in toluene (20 mL) was added
R,R-dippach (1.6 mL, 4.0 mmol). The mixture was stirred for 2 h
under reflux. Then the solvent was removed under vacuum and
the residue washed three times with petroleum ether. A micro-
crystalline orange solid was formed which was dried in vacuo.
Yield: 2.2 g, 80%. Anal. Calcd for C23H45N2ClP2Ru: C, 50.4; H,
1
8.28; N, 5.11. Found: C, 49.9; H, 8.39; N, 5.55. H NMR (400
MHz, C6D6, 298 K): δ 0.92 and 1.22 (m, 24 H, PCH(CH3)2), 1.46
(m, 8H, (CH2), 1.86 (m, 2 H, NH), 2.27 (m, 4 H, PCH(CH3)2),
3.87 (m, 2 H, (CH)2(CH2)4), 4.67 (s, 5 H, Cp). 31P{1H} NMR
(161.89 MHz, C6D6, 298 K): δ 112.6 (d, Jpp ) 51 Hz), 113.8 (d,
Jpp ) 51 Hz). 13C{1H} NMR (75.4 MHz, C6D6, 298 K): δ 15.8,
17.1, 18.6, 18.9, 19.5, 19.7, 19.9 and 20.9 (all s, PCH(CH3)2)), 25.4,
25.8, 27.1 and 28.2 (all s, (CH2)4), 34.5, 35.9, 36.8 and 37.5 (m,
PCH(CH3)2), 57.8 and 59.8 (s, (CH)2(CH2)4), 76.3 (s, Cp).
(3a) was prepared. The structure of 5a has been determined
by X-ray single-crystal diffraction, and a cation drawing is
presented in Figure 6. The structure of this Cp sandwich
cation is similar to that of its related Cp* complex [(η5-C5-
Me5)Ru(η6-C6H5F)]+ obtained like a subproduct by chloride
abstraction from diphosphine complexes of formula [Cp*RuCl-
(PP)].38 Ru-C bond distances are in the normal range
obtained for other sandwich or arene complexes of Ru(II).
[(η5-C5Me5)RuCl(R,R-dippach)] (1b). To a solution of {(η5-
C5Me5)RuCl}4 (1 g, 3.6 mmol) in petroleum ether (20 mL) was
added R,R-dippach (1.5 mL, 3.6 mmol). The mixture was stirred
at room temperature for 5 min, and an orange microcrystalline solid
precipitated. The solid was filtered out and dried in vacuo. Yield:
1.6 g (72%). Anal. Calcd for C28H55N2ClP2Ru: C, 54.4; H, 8.97;
Conclusion
1
Novel coordinatively unsaturated ruthenium semisandwich
complexes with phosphinoamine ligands and some other
related species as dinitrogen and dioxygen complexes are
reported. The high reactivity of these 16 electron species is
well-known as well as some pathways in which they achieve
a relative increase in stability: (1) the formation of dimers
or oligomers; (2) the reaction to trap small molecules; (3)
the interaction with an agostic H atom in a ligand group,
etc. A new way in which the unsaturated species achieve
relative stability is now reported. It consists in a mode of
coordination not yet described: the chelating phosphinoam-
ine bond to the metal center using three donor atoms and in
one side of the chelate ring the metal receiving electron
charge simultaneously from a vicinal pair of soft and hard
bases (η2-P,N). Comparing phosphinoamine ligands dippae
and R,R-dippach, DFT studies have pointed out that a
tridentate 18-electron structure is reached because of less
destabilization, in the case of R,R-dippach, by ligand
distortion bringing near to the metal a N atom which
coordination sufficiently compensates in such case the
destabilization energy.
N 4.53. Found: C, 54.1; H, 8.90; N, 4.25. H NMR (400 MHz,
CDCl3, 298 K): δ 1.16 (m, 24 H, PCH(CH3)2), 1.27 (m, 8H, (CH2),
1.55(s, 15 H, C5(CH3)5), 1.79 (m, 2 H, NH), 2.12 (m, 4 H,
PCH(CH3)2), 2.93 (m, 2 H, (CH)2(CH2)4). 31P{1H} NMR (161.89
MHz, CDCl3, 298 K): δ 108.3 (d, Jpp ) 58 Hz), 111.7 (d, Jpp
)
58 Hz). 13C{1H} NMR (75.4 MHz, CDCl3, 298 K): δ 10.8 (s,
C5(CH3)5), 18.0, 18.2, 18.3, 19.1, 19.5, 19.9 and 20.0 (all s, PCH-
(CH3)2)), 25.2, 25.6, 28.7 and 29.4 (all s, (CH2)4), 31.4, 34.2, 35.1
and 36.2 (m, PCH(CH3)2), 57.6 and 60.3 (s, (CH)2(CH2)4), 88.1 (s,
C5(CH3)5).
[(η5-C5H5)RuCl(dippae)] (1c). This compound was obtained in
a fashion analogous to that for 1a, starting from [(η5-C5H5)RuCl-
(PPh3)2] (3 g, 4.0 mmol) and dippae (1.2 mmol). Yield: 1.6 g
(80%). Anal. Calcd for C19H39N2ClP2Ru: C, 46.2; H, 7.96; N, 5.67.
Found: C, 45.9; H, 8.10; N, 5.74. 1H NMR (400 MHz, C6D6, 298
K): δ 0.84, 1.07 and 1.41 (m, 24 H, PCH(CH3)2), 1.98 (m, 2 H,
NH), 2.13 and 2.26 (m, 4 H, PCH(CH3)2), 2.67 and 3.01 (m, 4 H,
(45) Tilley, T. D.; Grubbs, R. H.; Bercaw, J. E. Organometallics 1984, 3,
274.
(46) Brookhart, M.; Grant, B.; Volpe, A. F., Jr. Organometallics 1992,
11, 3920.
(47) Wiegraebe, W.; Bock, H. Chem. Ber. 1968, 101, 1414.
(48) Miyano, S.; Nawa, M.; Hashimoto, H. Chem. Lett. 1980, 729.
Inorganic Chemistry, Vol. 46, No. 17, 2007 6965

Palacios et al.
(CH2)), 4.60 (s, 5 H, Cp). 31P{1H} NMR (161.89 MHz, C6D6, 298
K): δ 118.0 (s). 13C{1H} NMR (75.4 MHz, C6D6, 298 K): δ 17.5,
18.0, 19.1 and 19.8 (m, PCH(CH3)2)), 31.1 and 31.9 (m, PCH-
(CH3)2), 45.8 (s, (CH2)2), 76.5 (C5H5).
H, Cp). 31P{1H} NMR (161.89 MHz, CD2Cl2, 298 K): δ 110.6 (d,
2JPP ) 39 Hz), 112.5 (d, 2JPP ) 39 Hz). 13C{1H} NMR (75.4 MHz,
CD2Cl2, 298 K): δ 16.1, 16.3, 17.4, 18.2, 18.8 and 19.7 (all s,
PCH(CH3)2)), 24.6 and 25.3 (all s, (CH2)4), 34.8 and 35.8 (m, PCH-
(CH3)2), 58.0 and 59.8 (s, (CH)2(CH2)4), 81.8 (s, Cp).
[(η5-C5Me5)RuCl(dippae)] (1d). This compound was obtained
by following the same procedure used for 1b, starting from {(η5-
C5Me5)RuCl}4 (1 g, 3.6 mmol) and dippae (1.1 mmol). Yield: 1.6
g (80%). Anal. Calcd for C24H49N2ClP2Ru: C, 51.1; H, 8.75; N,
4.97. Found: C, 51.6; H, 8.91; N, 5.04. 1H NMR (400 MHz, C6D6,
298 K): δ 1.04 (m, 24 H, PCH(CH3)2), 1.66 (C5(CH3)5), 1.70 (m,
2 H, NH), 2.12 (m, 4 H, PCH(CH3)2), 2.87 and 3.19 (m, 4 H,
(CH2)). 31P{1H} NMR (161.89 MHz, C6D6, 298 K): δ 111.5 (s).
13C{1H} NMR (75.4 MHz, C6D6, 298 K): δ 10.8 (s, C5(CH3)5),
18.4, 19.0, 19.4 and 19.8 (s, PCH(CH3)2)), 29.8 (m, PCH(CH3)2),
46.4 (s, (CH2)2), 88.5 (C5H5).
[(η5-C5Me5)Ru(N2)(R,R-dippach)][BAr′4] (3b). This compound
was obtained by following the same procedure used for of 3a,
starting from 1b (0.6 g, 1 mmol). Yield: 0.52 g (40%). Anal. Calcd
for C60H67N4P2F24BRu: C, 48.9; H, 4.58; N, 3.80. Found: C, 49;
H, 4.25; N, 3.96. IR (Nujol): ν (N2) 2142 (s) cm-1. 1H NMR (400
MHz, CD2Cl2, 298 K): δ 1.17 (m, 32 H, PCH(CH3)2, (CH2)), 1.70
(s, 15 H, C5(CH3)5), 1.82 (m, 2 H, NH), 2.07 (m, 4 H, PCH(CH3)2),
3.22 (m, 2 H, (CH)2(CH2)4). 31P{1H} NMR (161.89 MHz, CD2Cl2,
2
2
298 K): δ 99.7 (d, JPP ) 47 Hz) and 102.0 (d, JPP ) 47 Hz).
[(η5-C5H5)Ru(N2)(dippae)][BAr′4] (3c). This compound was
obtained by following the same procedure used for of 3a, starting
from 1c (0.6 g, 1 mmol). Yield: 1.6 g (80%). Anal. Calcd for:
C51H51N4P2F24BRu: C, 45.4; H, 3.81; N, 4.15. Found: C, 45.3; H,
[(η5-C5Me5)Ru(R,R-dippach)][BAr′4] (2b). To a solution of 1b
(0.6 g, 1 mmol) in fluorobenzene (12 mL) under argon was added
NaBAr′4 (0.9 g, 1 mmol). The mixture was stirred at room
temperature for 10 min. Sodium chloride was removed by filtration
through Celite. The filtrate was concentrated to obtain a micro-
crystaline orange solid. Yield: 0.40 g (40%). Anal. Calcd for
C60H67N2P2F24BRu: C, 49.2; H, 4.65; N, 3.70. Found C, 49.3; H,
1
3.90; N, 4.25. IR (Nujol): ν (N2) 2178 (s) cm-1. H NMR (400
MHz, CD2Cl2, 298 K): δ 1.05 and 1.25 (m, 24 H, PCH(CH3)2),
1.65 (m, 2 H, NH), 2.08 and 2.13 (m, 4 H, PCH(CH3)2), 2.98 and
3.21 (m, 4 H, (CH2)), 4.75 (s, 5 H, Cp). 31P{1H} NMR (161.89
MHz, CD2Cl2, 298 K): δ 99.1 (s). 13C{1H} NMR (75.4 MHz,
CD2Cl2, 298 K): δ 18.2, 18.5, 19.1 and 19.7 (m, PCH(CH3)2)),
32.1 and 32.9 (m, PCH(CH3)2), 46.2 (s, (CH2)2), 76.9 (C5H5).
[(η5-C5Me5)Ru(N2)(dippae)][BAr′4] (3d). This compound was
obtained by following the same procedure used for of 3a, starting
from 1d (0.6 g, 1 mmol). Yield: 0.42 g (50%). Anal. Calcd for
C56H61N4F24P2BRu: C, 47.4; H, 4.33; N, 3.95. Found: C, 47.6; H,
1
4.57; N, 3.85. H NMR (400 MHz, CD2Cl2, 298 K): δ 1.17 (m,
32 H, PCH(CH3)2, (CH2)), 1.70 (s, 15 H, C5(CH3)5), 1.82 (m, 2 H,
NH), 2.07 (m, 4 H, PCH(CH3)2), 3.22 (m, 2 H, (CH)2(CH2)4). 31P-
{1H} NMR (161.89 MHz, CD2Cl2, 298 K): δ 92.3 (s). 13C{1H}
NMR (75.4 MHz, CD2Cl2, 298 K): δ 10.8 (s, C5(CH3)5), 18.1,
18.3, 19.1, 19.3, 19.4, 19.5, 19.8 and 20.0 (s, PCH(CH3)2)), 25.2,
25.6, 28.7 and 32.2 and 35.6 (s, (CH2)4), 35.1 and 36.2 (m, PCH-
(CH3)2), 57.7 and 60.3 (s, (CH)2(CH2)4), 88.1 (s, C5(CH3)5).
[(η5-C5Me5)Ru(dippae)][BAr′4] (2d). To a solution of 1d (0.6
g, 1 mmol) in fluorobenzene (12 mL) under argon was added
NaBAr′4 (0.9 g, 1 mmol). The mixture was stirred for 5 min, and
a change color from orange to dark blue was observed. The solution
was filtered through Celite, and the filtrate was concentrated under
reduced pressure to a volume of ca. 1 mL and then layered with
petroleum ether and left undisturbed at room temperature. Blue
crystals were obtained by slow diffusion of petroleum ether into
the fluorobenzene. The crystals were separated from the supernatant
liquor, washed with petroleum ether, and dried in an argon stream.
Yield: 0.42 g (50%). Anal. Calcd for C56H61N2F24P2BRu: C, 47.6;
H, 4.43; N, 2.88. Found: C, 47.9; H, 4.47; N, 2.84. 1H NMR (400
MHz, CD2Cl2, 298 K): δ 1.10, 1.26 and 1.37 (m, 24 H, PCH-
(CH3)2), 1.59 (C5(CH3)5), 2.34 and 2.48 (m, 4 H, PCH(CH3)2), 2.79
and 3.11 (m, 4 H, (CH2)), NH hydrogens not observed. 31P{1H}
NMR (161.89 MHz, CD2Cl2, 298 K): δ 96.4 (s). 13C{1H} NMR
(75.4 MHz, CD2Cl2, 298 K): δ 11.8 s, C5(CH3)5), 14.4, 14.7, 15.7,
19.8, 21.1 and 23.1 (s, PCH(CH3)2)), 30.8 and 34.9 (m, PCH(CH3)2),
42.1 (s, (CH2)2), 66.3 (C5(CH3)5).
1
3.39; N, 3.84. IR (Nujol): ν (N2) 2201 (s) cm-1. H NMR (400
MHz, CD2Cl2, 298 K): δ 1.15 (m, 24 H, PCH(CH3)2), 1.69
(C5(CH3)5), 1.70 (m, 2 H, NH), 2.35 (m, 4 H, PCH(CH3)2), 2.80
and 3.08 (m, 4 H, (CH2)). 31P{1H} NMR (161.89 MHz, CD2Cl2,
298 K): δ 92.6(s). 13C{1H} NMR (75.4 MHz, CD2Cl2, 298 K): δ
10.2 s, C5(CH3)5), 19.1, 19.2, 19.4 and 19.9 (s, PCH(CH3)2)), 30.2
(m, PCH(CH3)2), 47.6 (s, (CH2)2), 90.2 (C5(CH3)5).
[(η5-C5H5)Ru(O2)(R,R-dippach)][BPh4] (4a). Complex 1a (0,6
g, 1 mmol) was dissolved in MeOH in the air. Addition of an excess
of solid NaBPh4 (0.5 g) produced a yellow precipitate, which was
filtered out, washed with ethanol and light petroleum, and dried in
vacuo. Yield: 0.30 g (35%). Anal. Calcd for C47H65N2O2P2BRu:
1
C, 65.3; H, 7.58; N, 3.24. Found: C, 65.4; H, 7.69; N, 3.17. H
NMR (400 MHz, CDCl3, 298 K): δ 1.28 (m, 32 H, PCH(CH3)2,
(CH2)), 1.90 (m, 2 H, NH), 2.17 and 2.69 (m, 4 H, PCH(CH3)2),
3.14 (m, 2 H, (CH)2(CH2)4), 5.33 (s, 5 H, Cp). 31P{1H} NMR
2
(161.89 MHz, CDCl3, 298 K): δ 103.0 (d, JPP ) 35 Hz), 104.4
2
(d, JPP ) 35 Hz). 13C{1H} NMR (75.4 MHz, CD2Cl2, 298 K): δ
16.1, 16.3, 17.4, 18.2, 18.8 and 19.7 (all s, PCH(CH3)2)), 24.6 and
25.3 (all s, (CH2)4), 34.8 and 35.8 (m, PCH(CH3)2), 58.0 and 59.8
(s, (CH)2(CH2)4), 81.8 (s, Cp).
[(η5-C5H5)Ru(N2)(R,R-dippach)][BAr′4] (3a). To a solution of
1a (0.6 g, 1 mmol) in fluorobenzene (12 mL) under a N2 atmosphere
was added solid NaBAr′4 (0.9 g, 1 mmol). The mixture was stirred
for minutes at room temperature. Sodium chloride was removed
by filtration through Celite. After concentration of the resulting
solution to a volume of ca. 1 mL, petroleum ether was added and
the resulting solution was left undisturbed at room temperature. A
microcrystalline yellow solid was formed, which was separated from
the supernatant liquor, washed with petroleum ether, and dried in
vacuo. Yield: 0.71 g (60%). Anal. Calcd for C55H57N4P2F24BRu:
C, 47.1; H, 4.09; N, 3.99. Found: C, 47.6; H, 4.25; N, 3.86. IR
[(η5-C5Me5)Ru(O2)(R,R-dippach)][BPh4] (4b). This compound
was obtained by following the same procedure used for of 4a,
starting from 1b (0.6 g, 1 mmol). Yield: 0.52 g (40%). Anal. Calcd
for C52H75N2O2P2BRu: C, 66.8; H, 8.09; N, 3.00. Found: C, 66.9;
1
H, 8.16; N, 3.10. H NMR (400 MHz, CDCl3, 298 K): δ 0.98,
1.18 and 1.35 (m, 32 H, PCH(CH3)2, (CH2)), 1.52 (s, 15 H, C5-
(CH3)5), 2.15 (m, 2 H, NH), 1.99 and 2.30 (m, 4 H, PCH(CH3)2),
2.79 and (m, 2 H, (CH)2(CH2)4). 31P{1H} NMR (161.89 MHz,
2
2
CDCl3, 298 K): 86.2 (d, JPP ) 47.5 Hz), 94.4 (d, JPP ) 47.5
Hz). 13C{1H} NMR (75.4 MHz, CDCl3, 298 K): δ 10.5 (s,
C5(CH3)5), 15.9, 18.7, 19.4 and 20.2 (m, PCH(CH3)2)), 24.4, 26.5,
1
(Nujol): ν (N2) 2186 (s) cm-1. H NMR (400 MHz, CD2Cl2, 298
2
K): δ 1.19 (m, 32 H, PCH(CH3)2, (CH2)), 1.82 (m, 2 H, NH),
2.29 (m, 4 H, PCH(CH3)2), 2.84 (m, 2 H, (CH)2(CH2)4), 5.14 (s, 5
29.0 and 32.7 (all d, JCP ) 27 Hz, (CH2)4), 34.7 and 35.8 (m,
PCH(CH3)2), 57.5 and 60.2 (s, (CH)2(CH2)4), 106.2 (s, C5(CH3)5).
6966 Inorganic Chemistry, Vol. 46, No. 17, 2007

Complexes of Ruthenium with Phosphinoamine Ligands
[(η5-C5Me5)Ru(O2)(dippae)][BPh4] (4d). This compound was
obtained by following the same procedure used for of 4a, starting
from 1d (0.6 g, 1 mmol). Yield: 0.42 g (50%). Anal. Calcd for:
C44H69N2O2P2BRu: C, 63.5; H, 8.36; N, 3.37. Found: C, 63.5; H,
5a some of the F atoms in CF3 groups were disordered over two
positions. Only the part with sof > 0.5 was refined anisotropically
Additionally, in the case of 5a the cation was found disordered in
two positions. In both of them half of the occupation was attributed
to η5-C5H5 and half to η6-C6H5F (fluorobenzene). These C and F
atoms were isotropically refined. The hydrogen atoms were refined
using the SHELX riding model. The program ORTEP-351 was used
for plotting. CCDC 605986-605988 files giving crystallographic
data for 2b, 3a, and 5a and CCDC 638106 for 4d′ are available
free of charge via Internet at http://www.ccdc.cam.ac.uk/conts/
retrieving.html or as Supporting Information at http://pubs.acs.org.
Computational Details. The calculations have been performed
using the Gaussian03 package.52 The geometries have been fully
optimized using density functional theory with the B3LYP
functional.53-55 For the Ru and P atoms, the lanl2dz effective core
potential has been used to describe the inner electrons,52,56,57 whereas
their associated double-ú basis set has been employed for the
remaining electrons. An extra series of d-polarization functions has
also been added for P (expt 0.387).58 For all the carbon and nitrogen
atoms the 6-31G(d) basis set has been used. H atoms have been
described by the 6-31G basis set.59-61
1
8.39; N, 3.84. H NMR (400 MHz, CDCl3, 298 K): δ 1.15-1.32
(m, 24 H, PCH(CH3)2), 1.51 (C5(CH3)5), 1.74 (m, 2 H, NH), 2.33
(m, 4 H, PCH(CH3)2), 2.55 and 2.83 (m, 4 H, (CH2)). 31P{1H} NMR
(161.89 MHz, CDCl3, 298 K): δ 87.2 (s). 13C{1H} NMR (75.4
MHz, CDCl2, 298 K): δ 10.3 s, C5(CH3)5), 17.6, 18.8 and 19.3 (s,
PCH(CH3)2)), 31.4 (m, PCH(CH3)2), 45.3 (s, (CH2)2), 100.7
(C5(CH3)5).
[(η5-C5Me5)Ru(η2-O2)(dippae)][BAr′4] (4d′). This compound
was obtained by following the same procedure used for of 4a,
starting from 1d (0.6 g, 1 mmol). Yield: 1.18 g (83%). Anal. Calcd
for: C56H61N2F24O2P2BRu: C, 47.2; H, 4.28; N, 1.97. Found: C,
1
47.6; H, 4.35; N, 1.8. IR: ν(NH) 33340-3345 cm-1. H NMR
(400 MHz, CDCl3, 298 K): δ 1.15-1.35 (m, 24 H, PCH(CH3)2),
1.54 (s, 15H, C5(CH3)5), 1.75 (m, 2 H, NH), 2.35 (m, 4 H,
PCH(CH3)2), 2.57 and 2.80 (m, 4 H, (CH2)), 7.48-7.6 (m, 12 H,
C6H3(CF3)2. 31P{1H} NMR (161.89 MHz, CDCl3, 298 K): δ 88.2
(s). 13C{1H} NMR (75.4 MHz, CDCl2, 298 K): δ 10.9 s, C5(CH3)5),
17.9, 19.0, 19.4 and 19.9 (s, PCH(CH3)2)), 32.1 (m, PCH(CH3)2),
46.0 (s, (CH2)2), 102.5 (C5(CH3)5), 116.7 (s, Cpara of Ar′), 123.9
Acknowledgment. We thank the Spanish Ministerio de
Educacio´n y Ciencia (Projects CTQ2004-00776/BQU and
CTQ2005-09000-CO2-01 and Grant BES2002-1422 to
M.D.P.) and Junta de Andalucia (Group PAI FQM188 and
Project PAI05 FQM00094) for financial support, Johnson
Matthey plc for generous loans of ruthenium trichloride, and
L. M. Rodriguez Jaren for his help in X-ray data collection.
E.V. acknowledges the European Commission through the
HYDROCHEM program (Contract HPRN-CT-2002-00176).
The use of the computational facilities at the Centre de
Supercomputacio´ de Catalunya (CESCA) is appreciated as
well.
1
(q, JCF ) 270 Hz, CF3 of Ar′), 128.0 (m, Cmeta of Ar′), 134.0 (s,
1
Cortho of Ar′), 160.9 (q, JBC ) 49 Hz, Cipso of Ar′).
[Ru(η5-C5H5)(η6-C6H5F)][BAr′4] (5a). From solutions of dini-
trogen complex 3a or dioxygen complex 4a in fluorobenzene, the
presence of 16 electron [(η5-C5H5)Ru(R,R-dippach)]+ produced the
coordination of the solvent and a small fraction of colorless crystals
of [Ru(η5-C5H5)(η6-C6H5F)][BAr′4] was obtained. Anal. Calcd for
C43H22F25BRu: C, 50.4; H, 2.16. Found: C, 50.3; H, 2.30. 1H NMR
(400 MHz, CDCl3, 298 K): δ 4.68 (s, 5 H, Cp), 5.56, 6.15 (bs, 5
H, C6H5F), 7.48-7.6 (m, 12 H, {C6H3(CF3)2}4). 13C{1H} NMR
(75.4 MHz, CD2Cl2, 298 K): δ 16.1, 16.3, 17.4, 18.2, 18.8 and
19.7 (all s, PCH(CH3)2)), 24.6 and 25.3 (all s, (CH2)4), 34.8 and
35.8 (m, PCH(CH3)2), 58.0 and 59.8 (s, (CH)2(CH2)4), 81.8 (s, Cp).
Supporting Information Available: Complete ref 52 and
Cartesian coordinates and absolute energies for the optimized
structures. This material is available free of charge via the Internet
at http://pubs.acs.org
X-ray Structure Determinations. Suitable crystals for X-ray
diffraction analysis were obtained for compounds 2b, 3a, 5a, and
4d′. In each case a single crystal was mounted on a glass fiber to
carry out the crystallographic study. Crystal data and experimental
details are given in Table 2. X-ray diffraction data collections were
measured at 100 K on a Bruker Smart APEX CCD 3-circle
diffractometer using a sealed tube source, graphite-monochromated
Mo KR radiation (λ ) 0.710 73 Å), at the Servicio Central de
Ciencia y Tecnolog´ıa de la Universidad de Ca´diz. Diffraction data
were recorded in four sets of frames over a hemisphere of the
reciprocal space by ω scan with δ(ω) 0.30° and exposure of 10
s/frame. Correction for absorption and crystal decay (insignificant)
were applied by semiempirical method from equivalents using
program SADABS.49 The structures were solved by direct methods,
completed by subsequent difference Fourier syntheses, and refined
on F2 by full-matrix least-squares procedures using the programs
contained in SHELXTL package.50 Most of non-hydrogen atoms
were refined with anisotropic displacement parameters. For 2b and
IC700674C
(50) SHELXTL, v. 6.10; Bruker-AXS: Madison, WI, 2000. Sheldrick, G.
M. SHELXS-86 and SHELXL-97; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.
(51) Faruggia, L. J. ORTEP-3 for Windows, version 1.08. J. Appl.
Crystallogr. 1997, 30, 565.
(52) Frisch, M. J.; et al. Gaussian 03; Gaussian, Inc.: Wallingford, CT,
2004.
(53) Lee, C.; G.; Yang, W.; Parr, R. Phys. ReV. 1988, 37, B785.
(54) Becke, A. D. J. Phys. Chem. 1993, 98, 5648.
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Phys. Chem. 1994, 98, 11623.
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(58) Ho¨llwarth, A.; Bo¨hme, M.; Dapprich, S.; Ehlers, A. W.; Gobbi, A.;
Jonas, V.; Ko¨hler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G.
Chem. Phys. Lett. 1993, 208, 237.
(59) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Phys. Chem. A 1972, 56,
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Go¨ttingen, Germany, 2001.
Inorganic Chemistry, Vol. 46, No. 17, 2007 6967