Cycloruthenated complexes from iminophosphoranes: Synthesis, structure, and reactivity with internal alkynes

Article abstract of DOI:10.1021/om100997x

Cycloruthenated complexes [(η⁶-arene)Ru(C₆H ₄-2-PPh₂=NR)Cl] (arene = benzene, p-cymene; R = Ph, H) containing orthometalated iminophosphoranes have been obtained by transmetalation reactions from Hg(C₆

Full text of DOI:10.1021/om100997x

642 Organometallics 2011, 30, 642–648
DOI: 10.1021/om100997x
Cycloruthenated Complexes from Iminophosphoranes: Synthesis,
Structure, and Reactivity with Internal Alkynes
David Aguilar,† Raquel Bielsa,† Tatiana Soler,‡ and Esteban P. Urriolabeitia*,†
†
ꢀ
ꢀ
Departamento de Compuestos Organometalicos, Instituto de Ciencia de Materiales de Aragon,
ꢀ
‡
ꢀ
CSIC-Universidad de Zaragoza, 50009, Zaragoza, Spain, and Servicios Tecnicos de Investigacion,
Facultad de Ciencias Fase II, 03690, San Vicente de Raspeig, Alicante, Spain
Received October 20, 2010
Cycloruthenated complexes [(η6-arene)Ru(C6H4-2-PPh2dNR)Cl] (arene = benzene, p-cymene;
R = Ph, H) containing orthometalated iminophosphoranes have been obtained by transmetalation
reactions from Hg(C6H4-2-PPh2dNR)2 derivatives to [(η6-arene)Ru(μ-Cl)Cl]2. These complexes
react cleanly with internal alkynes R1CtCR2 (R1, R2 = Ph, Et, CO2Me), KPF6, and CuBr2, yielding
the 1,1,2-triphenyl-3,4-di(alkyl/aryl)-2,1λ5-benzazaphosphinin-2-ium heterocycles [C6H4-PPh2-
NPh-C(R1)dC(R2)-3,4]þ as PF6 salts. In all studied cases only the monoinsertion products have
been observed. In the case of the asymmetric alkyne MeCtCPh the insertion is regioselective, and the
[C6H4-PPh2-NPh-C(Me)dC(Ph)-3,4]PF6 salt is obtained.
Introduction
can even show a complementary reactivity with respect to
their Pd counterparts. The synthesis of different types of
heterocycles by reaction of metallacycles with alkynes2,3 is a
paradigm of this affirmation: cyclopalladated complexes can
insert one, two, or three equivalents of alkynes, as a function
of the orthometalated substrate and/or the substituents of
the alkyne,3a-c while most of the cycloruthenated derivatives
react with only a single equivalent, regardless of the nature of
the alkyne.3d-f
The use of orthometalated complexes as synthetic tools in
a variety of metal-mediated organic processes, either cataly-
tic or stoichiometric, is well established.1 Among different
transition metals, orthopalladated complexes are by far the
most used due to their versatility, stability, and availability.
However, it is also well known that other transition metals
can provide alternative behaviors, and, in some cases, they
We are interested in using iminophosphoranes as C,N-
bidentate ligands for the synthesis of orthometalated com-
plexes, because of their versatility, structural characteristics,
and applications.4 Among them, we have reported com-
plexes of Pd(II) and Au(III) as efficient catalysts for C-C
*To whom correspondence should be addressed. Fax: (þ34)
976761187. E-mail: esteban@unizar.es.
(1) For selected reviews about the use of orthometalated complexes in
organic synthesis see: (a) Vila, J. M.; Pereira, M. T. In Palladacycles;
Pfeffer, M.; Dupont, J., Eds.; Wiley-VCH: Weinheim, Germany, 2008;
Chapter 5. (b) Lyons, T. W.; Sanford, M. S. Chem. Rev. 2010, 110, 1147.
(c) Chen, X.; Engle, K. M.; Wang, D.-H.; Yu, J.-Q. Angew. Chem., Int. Ed.
2009, 48, 5094. (d) Ackermann, L.; Vicente, R.; Kapdi, A. R. Angew. Chem.,
Int. Ed. 2009, 48, 9792. (e) Thansandote, P.; Lautens, M. Chem.;Eur. J.
(3) Compared reactivity of Pd and Ru. Palladium derivatives: (a)
Maassarani, F.; Pfeffer, M.; LeBorgne, G. Organometallics 1987, 6,
2029. (b) Maassarani, F.; Pfeffer, M.; LeBorgne, G. Organometallics 1987,
6, 2043. (c) Ryabov, A. D.; Van Eldik, R.; LeBorgne, G.; Pfeffer, M.
Organometallics 1993, 12, 1386. Ruthenium derivatives: (d) Abbenhuis,
H. C. L.; Pfeffer, M.; Sutter, J. P.; DeCian, A.; Fischer, J.; Ji, H. L.; Nelson,
J. H. Organometallics 1993, 12, 4464. (e) Pfeffer, M.; Sutter, J. P.;
Urriolabeitia, E. P. Bull. Soc. Chim. Fr. 1997, 134, 947. (f) Ferstl, W.;
Sakodinskaya, I. K.; Beydoun-Sutter, N.; LeBorgne, G.; Pfeffer, M.; Ryabov,
A. D. Organometallics 1997, 16, 411.
~
2009, 15, 5874. (f) Muniz, K. Angew. Chem., Int. Ed. 2009, 48, 9412. (g)
Giri, R.; Shi, B.-F.; Engle, K. M.; Maugel, N.; Yu, J.-Q. Chem. Soc. Rev.
2009, 38, 3242. (h) Daugulis, O.; Do, H.-Q.; Shabashov, D. Acc. Chem. Res.
2009, 42, 1074. (i) Djukic, J.-P.; Sortais, J.-B.; Barloy, L.; Pfeffer, M. Eur. J.
Inorg. Chem. 2009, 817. (j) Park, Y. J.; Park, J.-W.; Jun, C.-H. Acc. Chem.
Res. 2008, 41, 222. (k) Alberico, D.; Scott, M. E.; Lautens, M. Chem. Rev.
2007, 107, 174. (l) Omae, I. J. Organomet. Chem. 2007, 692, 2608. (m)
Dick, A. R.; Sanford, M. S. Tetrahedron 2006, 62, 2439. (n) Godula, K.;
Sames, D. Science 2006, 312, 67. (o) Yu, J.-Q.; Giri, R.; Chen, X. Org.
Biomol. Chem. 2006, 4, 4041.
(4) (a) Bielsa, R.; Larrea, A.; Navarro, R.; Soler, T.; Urriolabeitia,
ꢀ
E. P. Eur. J. Inorg. Chem. 2005, 1724. (b) Aguilar, D.; Arag€ues, M. A.;
(2) For selected recent syntheses of heterocycles by reaction of
cyclometalated compounds with alkynes, see: (a) Davies, D. L.; Al-
Duaij, O.; Fawcett, J.; Singh, K. Organometallics 2010, 29, 1413. (b)
Boutadla, Y.; Davies, D. L.; Al-Duaij, O.; Fawcett, J.; Jones, R. C.; Singh, K.
Dalton Trans. 2010, 39, 10447. (c) Vicente, J.; Saura-Llamas, I.; Turpin, J.;
Bautista, D.; Ramírez de Arellano, C.; Jones, P. G. Organometallics 2009,
28, 4175. (d) Korivi, R. P.; Wu, Y.-C.; Cheng, C.-H. Chem.;Eur. J. 2009,
15, 10727. (e) Yamashita, M.; Hirano, K.; Satoh, T.; Miura, M. Org. Lett.
2009, 11, 2337. (f) Yamashita, M.; Horiguchi, H.; Hirano, K.; Satoh, T.;
Miura, M. J. Org. Chem. 2009, 74, 7481. (g) Arnau, P.; Nieto, S.; Serrano, E.;
Navarro, R.; Soler, T.; Cativiela, C.; Urriolabeitia, E. P. Inorg. Chem. 2009,
48, 11963. (h) Li, L.; Brennessel, W. W.; Jones, W. D. J. Am. Chem. Soc.
2008, 130, 12414. (i) Albert, J.; D'Andrea, L.; Granell, J.; Zafrilla, J.; Font-
Bardia, M.; Solans, X. J. Organomet. Chem. 2007, 692, 4895. (j) Spencer, J.;
Pfeffer, M.; DeCian, A.; Fischer, J. J. Org. Chem. 1995, 60, 1005.
Bielsa, R.; Serrano, E.; Navarro, R.; Urriolabeitia, E. P. Organometallics
ꢀ
2007, 26, 3541. (c) Aguilar, D.; Aznarez, F.; Bielsa, R.; Falvello, L. R.;
Navarro, R.; Urriolabeitia, E. P. Organometallics 2007, 26, 6397. (d) Bielsa,
ꢀ
R.; Navarro, R.; Lledos, A.; Urriolabeitia, E. P. Inorg. Chem. 2007, 46,
ꢀ
10133. (e) Aguilar, D.; Arag€ues, M. A.; Bielsa, R.; Serrano, E.; Soler, T.;
Navarro, R.; Urriolabeitia, E. P. J. Organomet. Chem. 2008, 693, 417. (f)
Bielsa, R.; Navarro, R.; Soler, T.; Urriolabeitia, E. P. Dalton Trans. 2008,
1203. (g) Bielsa, R.; Navarro, R.; Soler, T.; Urriolabeitia, E. P. Dalton Trans.
ꢀ
2008, 1787. (h) Aguilar, D.; Bielsa, R.; Contel, M.; Lledos, A.; Navarro, R.;
Soler, T.; Urriolabeitia, E. P. Organometallics 2008, 27, 2929. (i) Aguilar, D.;
Contel, M.; Navarro, R.; Soler, T.; Urriolabeitia, E. P. J. Organomet. Chem.
2009, 694, 486. (j) Aguilar, D.; Navarro, R.; Soler, T.; Urriolabeitia, E. P.
ꢀ
Dalton Trans. 2010, 39, 10422. (k) Aguilar, D.; Fernandez, I.; Cuesta, L.;
~
ꢀ
Yanez-Rodríguez, V.; Soler, T.; Navarro, R.; Urriolabeitia, E. P.; Lopez-Ortíz,
F. J. Org. Chem. 2010, 75, 6452.
r
pubs.acs.org/Organometallics
Published on Web 01/07/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 3, 2011 643
couplings,4a,h and we have studied the regioselectivity of
the cyclopalladation for N-benzyl,4d N-benzoyl,4b,h and
N-naphthyl4j substrates. In these studies we have deter-
mined that the orthopalladation of iminophosphoranes
contaning N-benzyl or N-naphthyl substituents can be
oriented toward the N-benzyl or the N-naphthyl ring at
low temperature or toward the P-aryl rings at high
temperature, while palladation of N-benzoyl derivatives
occurs exclusively at the benzoyl ring. This control has
allowed the regioselective functionalization;by iodina-
tion or CO insertion;of N-naphthyltri(aryl)phospho-
ranes, either at the P-aryl ring or at the N-naphthyl ring.4j
The facile insertion of CO into the Pd-C bond of these
derivatives and the subsequent observed C-N bond
coupling4j suggest that additional plausible functionaliza-
tion processes could arise from the reactions of the ortho-
palladated iminophosphoranes with other unsaturated
molecules, such as internal alkynes. However, despite multi-
ple attempts covering a variety of experimental conditions,
we have not observed the insertion of the alkyne on the
Pd-C bond of the orthopalladated iminophosphoranes. In
fact, the only report found in the bibliography about the
insertion of alkynes in orthopalladated iminophosphoranes
describes that this reaction takes place on the N-aryl ring of
[Pd-{C6H4(NdPPh3)-2}I(tmeda)],5 and only with the elec-
tron-poor alkyne DMAD (DMAD = MeO2C-CtC-CO2-
Me).
Chart 1. Iminophosphoranes Used in This Work
Scheme 1. Synthesis of the Coordination Compounds 2a-c
Due to this lack of reactivity, it seems reasonable to
attempt the reactivity of complexes with orthometalated
iminophosphoranes where the metal is no longer palladium.
We have chosen ruthenium as the metal, since orthoruthe-
nated complexes are very scarcely represented in the
literature6 and because they can show a complementary
reactivity toward internal alkynes with respect to the ortho-
palladated analogues.3
In this contribution we report the synthesis of new orthor-
uthenated complexes derived from iminophosphoranes and
their successful reactivity with internal alkynes to give 2,1λ5-
benzazaphosphinin-2-ium heterocycles.
i
MeC6H4 Pr)8b was attempted under different experimental
conditions reported in the literature.2a,b,3d,9
In the case of the potentially chelating iminophosphoranes
1a-c, only the coordination compounds 2a-c (Scheme 1)
were identified in the reaction crudes, while products derived
from a C-H bond activation were not detected even at traces
level. The syntheses shown in Scheme 1 for 2a-c represent
the optimized conditions for their preparation. In the case of
iminophosphoranes 1d-f untractable black suspensions
were obtained.
The lack of C-H bond activation in substrates 1a-c is
probably related with the initial chelate bonding of the
iminophosphoranes and the resulting fac-Cl,N,O or -Cl,N,
N arrangements. Once chelation has been produced, the
fragment PPh3 points away from the metal, avoiding their
mutual interaction and, hence, the possible C-H activation.
This effect is more evident in the case of 2a, due to the κ2-N,O
bonding mode. In fact, orthometalation of 1a is known in the
case of Pd and Pt,4a but the resulting ligand is κ3-C,N,N
coordinated, occupying three positions of the molecular
plane. Moreover, we have shown that orthopalladated imi-
nophosphoranes can also behave as κ3-C,N,P tridentate
ligands,4h,j but always the three donor atoms are coplanar
with the metal. None of these conditions can be satisfied
here. On the other hand, while the κ2-N,N bonding in 2b and
2c is expected, the reasons for the adoption of the κ2-N,O
bonding mode are not totally clear, but can be a consequence
of the oxophilic behavior of the Ru(II) center and the
minimization of steric interactions between the bulky PPh3
group and the η6-arene fragment.
Results and Discussion
1. Synthesis of Coordination Compounds. Aiming to per-
form the synthesis of the orthoruthenated compounds by
C-H bond activation, the reaction of the iminophosphor-
anes 1a-f7 (Chart 1) with the precursors [(η6-C6H6)Ru(μ-
8a
Cl)Cl]2 or [(η6-p-cymene)Ru(μ-Cl)Cl]2 (p-cymene = 1,4-
ꢀ
(5) Vicente, J.; Abad, J. A.; Clemente, R.; Lopez-Serrano, J.; Ramırez
´
de Arellano, M. C.; Jones, P. G.; Bautista, D. Organometallics 2003, 22,
4248.
ꢀ
a-Alvarez, J.; Gimeno, J. Organome-
(6) Cadierno, V.; Dıez, J.; Garcı
´ ´
tallics 2005, 24, 2801.
(7) Synthesis of 1a and 1d: (a) Bittner, S.; Assaf, Y.; Krief, P.;
Pomerantz, M.; Ziemmnicka, B. T.; Smith, C. G. J. Org. Chem. 1985,
50, 1712. Synthesis of 1b: (b) Abe, N.; Fujii, H.; Tahara, K.; Shiro, M.
Heterocycles 2001, 55, 1659. (c) Nagamatsu, K.; Akiyoshi, E.; Ito, H.; Fujii,
H.; Kakehi, A.; Abe, N. Heterocycles 2006, 69, 167. Synthesis of 1c: (d)
Spencer, L. P.; Altwer, R.; Wei, P.; Pingrong, G.; Gelmini, L.; Gauld, J.;
Stephan, D. W. Organometallics 2003, 22, 3841.
(8) Synthesis of [Ru(η6-C6H6)Cl(μ-Cl)]2: (a) Zelonka, R. A.; Baird,
M. C. Can. J. Chem. 1972, 50, 3063. (b) Bennett, M. A.; Smith, A. K. J.
Chem. Soc., Dalton Trans. 1974, 233. Synthesis of [Ru(η6-p-cymene)Cl(μ-
Cl)]2: (c) Bennett, M. A.; Huang, T. N.; Matteson, T. W.; Smith, A. K. Inorg.
Synth. 1982, 21, 75.
Complexes 2a-c show correct elemental analyses and
mass spectra for the proposed structures shown in Scheme 1.
The IR of 2a shows a strong absorption at 1534 cm-1, due
to the νCO stretch. This band has been shifted to lower
frequency when compared with that in the free ligand 1a
ꢀ
(9) (a) Fernandez, S.; Pfeffer, M.; Ritleng, V.; Sirlin, C. Organome-
tallics 1999, 18, 2390. (b) Davies, D. L.; Al-Duaij, O.; Fawcett, J.; Giardiello,
M.; Hilton, S. T.; Russell, D. R. Dalton Trans. 2003, 4132.

644 Organometallics, Vol. 30, No. 3, 2011
Aguilar et al.
Chart 2. Hg Compounds Used As Transmetalating Reagents for
the Synthesis of Ruthenacyccles
Scheme 2. Synthesis of the Orthometalated Compounds 4e-5f
(1601 cm-1),7a suggesting the O-bonding of the carbonyl
oxygen instead of the N-bonding of the iminic N atom. The
N-bonding of the iminophosphoranes in 2b and 2c is clearly
inferred from the shift to lower wavenumbers of the band due
to the νPN stretch, while, as expected, it remains essentially
unchanged in 2a. The NMR data are in good agreement with
the structures depicted in Scheme 1. Key features for 2a are
the presence of a 31P NMR signal with a chemical shift very
close to that of the free ligand 1a and a notable deshielding of
the pyridinic H6 proton, also with respect to 1a. Both facts
suggest that the ligand is bonded through the pyridinic N
atom and the carbonyl oxygen. In the case of 2b and 2c, the
31P NMR spectra show signals strongly shifted to low field,
indicating the iminic N-bonding, this fact being in keeping
with the IR data. Moreover, the downfield shifts of the ortho
protons of the quinoline (H2) and pyridine (H6) fragments
are diagnostic for their N-coordination in 2b and 2c. There-
fore, 2a contains an iminophosphorane κ2-N,O chelate, a
bonding mode already known and fully characterized in Pd
complexes,11 while 2b and 2c contain κ2-N,N chelates. The
molecular structure of 2a has been determined by X-ray
diffraction methods (see below).
2. Synthesis of Orthoruthenated Compounds. The synth-
esis of the cycloruthenated complexes has been successfully
accomplished through transmetalation processes.12 This
strategy is commonly used as an alternative to the C-H
bond activation reaction when a clear lack of reactivity of the
latter is observed. Previous work in ruthenium derivatives
has shown that the use of lithium species as transmetalating
agents is not the best choice, because of extensive reduction
and formation of black Ru, while Hg(II) or Zn(II) com-
plexes3d,e,13 behave as efficient transmetalating reagents
under mild reaction conditions. Therefore, the Hg(II) com-
plexes 3d-f shown in Chart 2 have been prepared using
literature procedures,4k,10 and we have tested their reactivity
toward Ru(II) precursors. The results are shown in Scheme 2.
The reaction of the arene derivative [(η6-C6H6)Ru(μ-
Cl)Cl]2 or [(η6-p-cymene)Ru(μ-Cl)Cl]2 with 3e and 3f (1:1
molar ratio) in CH2Cl2 at room temperature affords, after
elimination of the HgCl2, the cycloruthenated complexes
[(η6-arene)Ru{(C6H4)-2-Ph2PdNR-κ-C,N}Cl] (4e-5f, see
Scheme 2) as stable red solids in good yields. In all cases
the transmetalation occurs under very mild reaction condi-
tions. It is noteworthy that the hydrolysis of the silyl group
from 3f occurs during the synthesis of complexes 4f and 5f,
which contain a NH fragment bonded to the Ru center. This
process is likely a consequence of the presence of traces of
water. Despite many attempts to obtain the expected silyl
derivatives, this small amount of water proved to be difficult
to remove, and 4f and 5f were systematically found as the
only reaction products. In complexes 4e-5f the ruthenium
atom is a stereogenic center. However, due to the absence of
additional chiral sources during their synthesis, 4e-5f are
obtained as racemic mixtures.
The nature of the arene does not seem to be very important
for the reaction outcome, since similar yields have been
obtained in the case of benzene and p-cymene. However,
both the electronic and steric nature of the iminophosphor-
ane exert a strong influence over the course of the reaction.
On one hand, we have attempted the transmetalation using
the corresponding monoaryl complexes [ClHg(C6H4-2-
PPh2dNR)], but low conversions were observed, even at
high temperatures, indicating that electron-rich bis-aryl
species are necessary to achieve high yields. Due to these
reasons, these reactions are not described here. On the other
hand, the steric hindrance of the iminophosphorane is also
important. For instance, the organomercury species 3d does
not react with the ruthenium precursors, even at the reflux
temperature, while sterically less demanding complexes 3e
and 3f react smoothly. Although the reasons remain spec-
ulative, it is sensible to assume that the observed results are
related to the large volume of the free iminophosphonium
group in 3d. As described above, this is the argument invoked
for the κ2-N,O bonding mode observed in 2a, and it is
probably playing a similar role here.
The characterization of 4e-5f is straighforward and fol-
lows the same basic key features than those described for
complexes 2. The IR spectra of 4e-5f show that the bands
assigned to the νPdN stretch (range 1279-1295 cm-1) appear
shifted to lower energies with respect to those of the free
ligands (around 1325 cm-1), suggesting N-bonding. The 1H
NMR spectra show the presence of signals due to the η6-
arene and C6H4P units. The characterization of the ruthena-
cycle is also evident from the observation of six well-resolved
peaks on the aromatic region of the 13C NMR spectra, due to
the C6H4P unit, and from the strong downfield shifts under-
gone by the 31P signals, appearing now in the 40-50 ppm
region, with respect to the free ligands, suggesting that the P
atom belongs to the metallacycle. In the case of 4f and 5f, the
N-H unit is characterized from both the IR (νNH at about
1
3200 cm-1) and the H NMR spectra (broad singlet at 0.9
ppm for 4f and doublet at 1.24 ppm for 5f). The molecular
structures of 4f and 5e have been determined by X-ray
diffraction methods (see below).
3. Synthesis of Heterocycles by C-C and C-N Coupling.
It has been reported3d-f that orthoruthenated complexes
derived from substituted benzylamines react with one
equivalent of alkynes to give tetrahydroisoquinolinium het-
erocycles. The reaction occurs through coordination of the
alkyne and migratory insertion into the Ru-C bond, with
(10) Synthesis of the Hg(II) derivatives. Compound 3e: (a) Stuckwish,
C. G. J. Org. Chem. 1976, 41, 1173. Compound 3f: (b) Steiner, A.; Stalke, D.
Angew. Chem., Int. Ed. 1995, 34, 1752. Compound 3d: see ref 4k.
ꢀ
´
(11) Falvello,L.R.;Garcıa, M. M.; Lazaro, I.; Navarro, R.; Urriolabeitia,
E. P. New J. Chem. 1999, 23, 227.
(12) Urriolabeitia, E. P. In Palladacycles; Pfeffer, M.; Dupont, J., Eds.;
Wiley-VCH: Weinheim, Germany, 2008; Chapter 3.
(13) Pfeffer, M.; Sutter, J. P.; Urriolabeitia, E. P. Inorg. Chim. Acta
1996, 249, 63.

Article
Organometallics, Vol. 30, No. 3, 2011 645
Scheme 3. Synthesis of the Heterocycles 6-9 by Alkyne
Insertion into the Ru-C Bond
concomitant C-C coupling, affording a vinylic intermedi-
ate. This vinylic species underwent reductive elimination of
the heterocyclic fragment through C-N coupling, affording
a Ru(0) species that could be isolated.3d,e This Ru(0) complex
contains a η4-bonded isoquinolinium ligand, which can be
released by oxidation with CuBr2. Aiming to obtain new
heterocycles, the reactivity of the orthoruthenated derivative
5e (as a representative compound) toward internal alkynes
with different substituents (EtCtCEt, MeO2CCtCCO2Me,
PhCtCPh, PhCtCMe) has been attempted. The results are
presented in Scheme 3.
The one-pot reaction of 5e with alkynes R1CtCR2, KPF6,
and CuBr2, following previously reported procedures,3e
affords the 1,1,2-triphenyl-3,4-di(alkyl/aryl)-2,1λ5-benzaza-
phosphinin-2-ium heterocycles [C6H4-PPh2-NPh-C(R1)d
C(R2)-3,4]þ as PF6 salts (6-9). The presence of KPF6 is
mandatory, since reactions performed in the absence of this
reagent did not afford the heterocyclic species. This reflects
the importance of the generation of a vacant site, by chloride
abstraction, position where the alkyne could be bonded to
initiate the reaction. In this respect, complex 5e inserts only
one equivalent of alkyne, even in the presence of an excess of
this reagent. This means that the reaction is completely
selective toward the formation of a single product, in good
agreement with previous observations.3d,e On the other
hand, attempts to isolate the putative Ru(0) intermediates
were unsuccessful; therefore only the one-pot processes have
been fully studied.
Compounds 6-9 were obtained as yellow-orange solids in
moderate to good yields. There is a clear relationship be-
tween the yield of the reaction and the nature of the alkyne
substituents. The reaction takes place more efficiently in the
case of electron-donating substituents, and the yield de-
creases notably as the electron-withdrawing ability of the
substituents increases: 6 (Et, 66%), 8 (Ph, 56%), 7 (CO2Me,
33%). It has been proposed3d-f that the reductive elimina-
tion takes place by nucleophilic attack of the vinylic carbon
to the coordinated nitrogen. Therefore, the lower yields of 7
compared with 6 can be explained due to the lower nucleo-
philicity of the ester-substituted vinylic carbon, compared
with the alkyl-substituted vinylic carbon. These results are
also in good agreement with previous observations in
benzylamines.3e The reactions of orthoruthenated benzyla-
mines with DMAD, or with other ester-substituted alkynes,
stopped at the insertion step and further reductive elimina-
tion from the vinylic intermediate did not occur, avoiding the
formation of the heterocycle.3e It is clear that the perfor-
mance of this system based on orthoruthenated iminopho-
sphoranes is better than that described previously with
benzylamines3e since, even in the case of the most electron-
deficient alkyne (DMAD), the reaction affords the expected
heterocycle. Moreover, it is also more efficient that those
based on palladium, where no reaction was observed
Figure 1. Molecular drawing of the cation of 2a. The PF6
counteranion has been removed for clarity. Selected distances
[A] and angles [deg]: Ru(1)-O(1) 2.082(2); Ru(1)-N(1)
2.090(3); Ru(1)-C(12) 2.160(3); Ru(1)-C(8) 2.165(4); Ru(1)-
C(11) 2.168(3); Ru(1)-C(10) 2.172(3); Ru(1)-C(7) 2.173(3);
Ru(1)-C(9) 2.182(3); Ru(1)-Cl(1) 2.3932(9); O(1)-C(1)
1.272(4); C(1)-N(2) 1.298(4); C(1)-C(2) 1.490(4); N(2)-P(1)
1.623(3); O(1)-Ru(1)-Cl(1) 85.06(7); N(1)-Ru(1)-Cl(1)
85.07(7); O(1)-Ru(1)-N(1) 77.48(9).
between the orthopalladated iminophosphorane and the
alkynes.
In the case of the asymmetric alkyne PhCtCMe, two
regioisomers are plausible. The NMR spectra of 9 show a
single set of resonances in each case; therefore 9 is obtained as
1
a single regioisomer. The H NOESY-1D experiments per-
formed show that the irradiation of the peak at 2.27 ppm
(Me) induces a clear enhancement on the ortho protons of
the N-Ph ring, giving proof of their spatial proximity. This
means that the less bulky methyl group is over the C atom
bonded to the nitrogen3d and that the attack of the alkyne to
the metal takes place avoiding NPh-Ph interactions. This
allows us to conclude that the origin of the regioselectivity is
based on steric factors. This result is in good agreement with
previous observations in ruthenacycles, although is it not
possible to make general rules since many parameters are
usually involved.14 In our case, even when groups with small
steric differences are considered, as in PhCtCMe, a com-
plete selectivity is observed.
Full characterization of the heterocyclic species 6-9 was
carried out on the basis of their analytic and spectroscopic
data. Therefore, 6-9 show correct elemental analyses for the
proposed stoichiometry, and their MS display peaks with the
correct isotopic distribution. The IR spectra show the νPdN
stretch in the 1285-1310 cm-1 region, while in the 31P NMR
spectra a single peak in each case appears in the range
29.5-35.0 ppm.
4. X-ray Molecular Structures of 2a, 4f, and 5e. A drawing
of the molecular structure of 2a is shown in Figure 1. The Ru
atom is in a pseudo-octahedral “piano-stool” environment,
where the benzene ligand is the stool and the legs are the
Ru-O, Ru-N, and Ru-Cl bonds. As a whole, all bond
distances and angles do not show deviations from values
found in the literature for structurally related complexes.
(14) Spencer, J.; Pfeffer, M.; Kyritsakas, N.; Fischer, J. Organome-
tallics 1995, 14, 2214.

646 Organometallics, Vol. 30, No. 3, 2011
Aguilar et al.
Figure 2. Molecular drawing of the cation of 5e. Selected dis-
tances [A] and angles [deg]: Ru(1)-C(1) 2.0574(18); Ru(1)-N-
(1) 2.1241(14); Ru(1)-C(27) 2.147(2); Ru(1)-C(31) 2.165(2);
Ru(1)-C(28) 2.1767(19); Ru(1)-C(26) 2.184(2); Ru(1)-C(29)
2.2516(18); Ru(1)-C(30) 2.2668(18); Ru(1)-Cl(1) 2.4067(6);
P(1)-N(1) 1.5980(15); C(1)-Ru(1)-N(1) 81.81(6); C(1)-Ru-
(1)-Cl(1) 82.91(6); N(1)-Ru(1)-Cl(1) 86.78(5).
Figure 3. Molecular drawing of the cation of 4f. Selected dis-
tances [A] and angles [deg]: Ru(1)-C(7) 2.050(4); Ru(1)-N(1)
2.121(3); Ru(1)-C(5) 2.137(4); Ru(1)-C(6) 2.136(4); Ru(1)-C-
(1) 2.151(4); Ru(1)-C(4) 2.177(4); Ru(1)-C(3) 2.212(4); Ru-
(1)-C(2) 2.262(5); Ru(1)-Cl(1) 2.4319(11); P(1)-N(1)
1.586(4); C(7)-Ru(1)-N(1) 80.44(17); C(7)-Ru(1)-Cl(1)
87.54(11); N(1)-Ru(1)-Cl(1) 85.92(9).
The average Ru-C(benzene) distance is 2.170(3) A, which is
similar to that found in [(η6-C6H6)RuCl(C6H4CH2NMe2)]
(2.18 A).3d Both the Ru(1)-O(1) [2.082(2) A] and the Ru-
(1)-N(1) [2.090(3) A] bond distances are slightly shorter
than those found in [(η6-p-cymene)RuCl(N-O)]A (N-O =
2-benzoylpyridine, A = PF6; 2-acetylpyridine, A = BPh4),15
while the Ru(1)-Cl(1) bond distance [2.3932(9) A] is slightly
longer than those found in the aforementioned complexes.
The bond angles O(1)-Ru(1)-Cl(1) [85.06(7)°], N(1)-Ru-
(1)-Cl(1) [85.07(7)°], and O(1)-Ru(1)-N(1) [77.48(9)°] are
identical, within experimental error, to those observed in
[(η6-p-cymene)RuCl(N-O)]A.15 Internal parameters of the
N,O-chelate are similar to those found in Pd complexes11 and
do not merit further comment.
selectivity, affording new benzazaphosphinin-2-ium hetero-
cycles, not achievable by other synthetic methods. The
method is highly tolerant to the nature of the alkyne substit-
uents and to the ligands around the Ru center, displaying a
high performance in all studied cases.
Experimental Section
General Methods. Solvents were dried and distilled using
standard procedures before use. Elemental analyses (CHNS)
were carried out on a Perkin-Elmer 2400-B microanalyzer.
Infrared spectra (4000-380 cm-1) were recorded on a Perkin-
1
Elmer Spectrum One IR spectrophotometer. H, 13C, and 31P
Drawings of the molecular structures of 5e and 4f are
shown in Figures 2 and 3, respectively. The two molecules
are isostructural, with the Ru atom in a pseudo-octahedral
“piano-stool” environment, similar to that described for 2a.
The couples of bond distances between the same atoms
involving the Ru center are identical, within experimental
error (for instance, 5e: Ru(1)-C(1) 2.0574(18) A, Ru(1)-N-
(1) 2.1241(14) A, and Ru(1)-Cl(1) 2.4067(6) A; 4f: Ru-
(1)-C(7) 2.050(4) A, Ru(1)-N(1) 2.121(3) A, and Ru-
(1)-Cl(1) 2.4319(11) A), and are also identical to those
found for similar complexes.3d,16 For instance, the experi-
mental values found in [(η6-C6H6)RuCl(C6H4CH2NMe2)]
are Ru-C [2.08(1) A], Ru-N [2.148(8) A], and Ru-Cl
[2.430(2) A].3d
NMR spectra were recorded in CDCl3 solutions at 25 °C on a
Bruker AV400 spectrometer (δ in ppm, J in Hz) at 1H operating
frequency of 400.13 MHz. 1H and 13C spectra were referenced
using the solvent signal as internal standard, while 31P spectra
were externally referenced to H3PO4 (85%). ESIþ mass spectra
were recorded using an Esquire 3000 ion-trap mass spectrometer
(Bruker Daltonic GmbH) equipped with a standard ESI/APCI
source. Samples were introduced by direct infusion with a
syringe pump. Nitrogen served both as the nebulizer gas and
the dry gas. The mass spectra (MALDIþ) were recorded from
CHCl3 solutions on a MALDI-TOF Microflex (Bruker) spec-
trometer (DCTB as matrix). The iminophosphoranes Ph3-
PdNPh, 1e, and Ph3PdNSiMe3, 1f, were obtained from com-
mercial sources and were used as received. The iminophosphor-
anes Ph3PdNC(O)-2-NC5H4, 1a,7a Ph3PdN-C9H6N, 1b,7b
Ph3PdNCH2-2-NC5H4, 1c,7c and Ph3PdNC(O)Ph, 1d,7a the
8a
ruthenium precursors [(η6-C6H6)Ru(μ-Cl)Cl]2 and [(η6-p-
Conclusion
i
cymene)Ru(μ-Cl)Cl]2 (p-cymene = 1,4-MeC6H4 Pr),8b and the
mercury compounds [Hg(C6H4C(O)NdPPh3)2], 3d,4k [Hg-
(C6H4-2-PPh2dNPh)2], 3e,10a and [Hg(C6H4-2-PPh2dNSi-
Me3)2], 3f,10b were prepared following literature procedures.
Synthesis of [(η6-C6H6)Ru((Ph3PdN-CO-2-NC5H4)-K-N,
O)Cl](PF6), 2a. A suspension of [(η6-C6H6)RuCl(μ-Cl)]2 (0.130
g, 0.26 mmol), 1a (0.200 g, 0.52 mmol), and KPF6 (0.092 g, 0.52
mmol) in MeOH (25 mL) was stirred at room temperature for
6 h. During this time the color of the suspension evolved from
red to deep yellow. After the reaction time the yellow solid was
filtered, washed with MeOH (5 mL) and Et2O (2 ꢀ 15 mL), and
The transmetalation reaction is an adequate synthetic
procedure for the preparation of new orthoruthenated deri-
vatives from iminophosphoranes. These cyclometalated
species react with internal alkynes with a high degree of
(15) Zuccaccia, D.; Bellachioma, G.; Cardaci, G.; Zuccaccia, C.;
Macchioni, A. Dalton Trans. 2006, 1963.
(16) Attar, S.; Nelson, J. H.; Fischer, J.; de Cian, A.; Sutter, J. P.;
Pfeffer, M. Organometallics 1995, 14, 4559.

Article
Organometallics, Vol. 30, No. 3, 2011 647
dried in vacuo. Obtained: 0.243 g (63% yield). Anal. Calcd for
[C30H25ClF6N2OP2Ru] (741.04): C, 48.58; H, 3.40; N, 3.78.
C6H4, 4JPC=3.1), 134.0 (d, Co, PPh2, 2JPC=11.3), 135.5 (d, Cp,
PPh2, 4JPC = 2.9), 140.8 (d, C6, C6H4, 3JPC=14.5), 153.4 (s, Ci,
NPh), 181.1 (s br, C1, C6H4). The signal due to C2 (C6H4) was
not observed. 31P{1H} NMR (CDCl3): δ 42.51.
Found: C, 48.43; H, 3.32; N, 3.53. IR: 1534 (νCdO), 1297(νPdN
)
cm-1. MS (FABþ): 597 (50%) [M - PF6]þ. 1H NMR (CDCl3):
δ 5.56 (s, 6H, η6-C6H6), 7.61 (m, 6H, Hm, PPh3), 7.71-7.96 (m,
10H, H5, C5H4N þ Hp þ Ho, PPh3), 8.02 (t, 1H, H4, C5H4N,
3JHH=7.4), 8.34 (d, 1H, H3, C5H4N, 3JHH=7.3), 9.21 (d, 1H, H6,
Synthesis of [(η6-p-cymene)Ru{(C6H4)-2-Ph2PdNPh-K-C,
N}Cl], 5e. Compound 5e was prepared following the same
synthetic method as that described for 4e. Therefore [(η6-p-
cymene)RuCl(μ-Cl)]2 (0.186 g, 0.30 mmol) was reacted with 3e
(0.273 g, 0.30 mmol) in 20 mL of CH2Cl2 to give 5e as a red
solid. Obtained: 0.168 g (45% yield). Anal. Calcd for
[C34H33ClNPRu] (623.13): C, 65.53; H, 5.34; N, 2.25. Found:
C, 65.10; H, 5.21; N, 2.18. IR: 1284 (νPdN) cm-1. MS
(MALDIþ): 623 (70%) [M]þ. 1H NMR (CDCl3): δ 0.98-1.04
(m, 6H, Me2-cymene), 1.98 (s, 3H, Me-cymene), 2.66 (m, 1H,
3
C5H4N, JHH =5.2). 13C{1H} NMR (CDCl3): δ 83.7 (s, η6-
3
C6H6), 127.8 (s, C3, C5H4N), 129.4 (d, Cm, PPh3, JPC=13.0),
129.7 (s, C5, C5H4N), 133.2 (d, Co, PPh3, 2JPC=10.8), 133.9 (d,
Cp, PPh3, 4JPC=2.9), 139.5 (s, C4, C5H4N), 151.5 (s, C2, C5H4N),
154.3 (s, C6, C5H4N), 178.1 (s, CO). 31P{1H} NMR (CDCl3): δ
26.72.
Synthesis of [(η6-C6H6)Ru((Ph3PdN-8-C9H6N)-K-N,O)Cl]-
(PF6), 2b. [(η6-C6H6)RuCl(μ-Cl)]2 (0.124 g, 0.25 mmol) was
reacted with 1b (0.200 g, 0.50 mmol) and KPF6 (0.091 g, 0.50
mmol) in MeOH (25 mL), as reported for 2a, to give 2b as an
orange solid. Obtained: 0.238 g (62% yield). Anal. Calcd for
[C33H27ClF6N2P2Ru] (764.04): C, 51.88; H, 3.56; N, 3.67.
Found: C, 51.21; H, 3.30; N, 3.51. IR: 1287 (νPdN) cm-1. MS
(MALDIþ): 619 (80%) [M - PF6]þ. 1H NMR (CDCl3): δ 5.18
(s, 6H, η6-C6H6), 6.32 (d, 1H, H7, C9H6N, 3JHH = 7.9), 6.84 (t,
CH-cymene), 4.51, 4.60, 4.81, 4.91 (4d, 4H, C6H4-cymene, 3JHH
=
5.6), 6.88-6.94 (m, 3H, Hp, NPh þ H3 þ H4, C6H4), 7.08 (t, 2H,
Ho, NPh, 3JHH=7.6), 7.23-7.33 (m, 3H, H5, C6H4 þ Hm, PPh),
7.36-7.41 (m, 3H, Hm, NPh, þ Hp, PPh), 7.50 (m, 2H, Hm,
PPh), 7.55-7.62 (m, 3H, Ho þ Hp, PPh), 7.81 (m, 2H, Ho, PPh),
8.20 (dd, 1H, H6, C6H4, 3JHH=7.6, 4JHH = 2.6). 13C{1H} NMR
(CDCl3): δ 18.7 (s, Me-cymene), 22.2, 22.4 (2s, Me2-cymene),
30.4 (s, CH-cymene), 77.8, 80.1, 87.4, 90.3, 97.0, 106.8 (6s, C6H4-
3
3
3
1H, H6, C9H6N, JHH=7.9), 7.07 (d, 1H, H5, C9H6N, JHH =
8.0), 7.55-7.68 (m, 9H, Hm þ Hp, PPh3), 7.75 (t, 1H, H3,
cymene), 122.2 (s, Co, NPh), 122.4 (d, C4, C6H4, JPC=13.7),
128.1-129.3 (ovelapped, Cp, NPh þ Cm, PPh þ Cp, PPh), 129.5
3
C9H6N, JHH=8.3), 7.91 (m, 6H, Ho, PPh3), 8.17 (d, 1H, H4,
2
(d, C3, C6H4, JPC=21.4), 130.7 (s, C5, C6H4), 131.8, 132.0
3
3
1
C9H6N, JHH =8.1), 9.30 (d, 1H, H2, C9H6N, JHH =5.0).
13C{1H} NMR (CDCl3): δ 84.5 (η6-C6H6), 117.8 (C5, C9H6N),
121.6 (C7, C9H6N), 127.2 (C6, C9H6N), 129.6 (Cm, PPh3), 132.7
(C3, C9H6N), 134.0 (Cp, PPh3), 134.5 (Co, PPh3), 138.5 (C4,
C9H6N), 153.7 (C2, C9H6N). Signals due to the quaternary C
atoms were not observed. 31P{1H} NMR (CDCl3): δ 39.42.
Synthesis of [(η6-C6H6)Ru((Ph3PdN-CH2-2-NC5H4)-K-N,
N)Cl](PF6), 2c. [(η6-C6H6)RuCl(μ-Cl)]2 (0.200 g, 0.40 mmol)
was reacted with 1c (0.294 g, 0.80 mmol) and KPF6 (0.147 g, 0.80
mmol) in MeOH (25 mL), as reported for 2a, to give 2c as a
yellow solid. Obtained: 0.384 g (66% yield). Anal. Calcd for
[C30H27ClF6N2P2Ru] (727.71): C, 49.51; H, 3.74; N, 3.85.
Found: C, 49.36; H, 3.62; N, 3.81. IR: 1291 (νPdN) cm-1. MS
(FABþ): 583 (65%) [M - PF6]þ. 1H NMR (CDCl3): δ 4.14 (t,
(overlapped, Cm, NPh þ Cp, PPh), 132.2 (d, Ci, PPh2, JPC
=
=
=
2
2
80.0), 133.3 (d, Co, PPh, JPC=9.5), 134.3 (d, Co, PPh, JPC
10.2), 136.3 (C2, C6H4, 1JPC=140.1), 141.0 (d, C6, C6H4, 3JPC
2
14.7), 153.4 (s, Ci, NPh), 183.4 (d, C1, C6H4, JPC = 23.3).
31P{1H} NMR (CDCl3): δ 43.04.
Synthesis of [(η6-C6H6)Ru{(C6H4)-2-Ph2PdNH-K-C,N}Cl],
4f. Compound 4f was prepared following the same synthetic
method as that described for 4e. Therefore [(η6-C6H6)RuCl(μ-
Cl)]2 (0.131 g, 0.26 mmol) was reacted with 3f (0.236 g, 0.26
mmol) in 20 mL of CH2Cl2 to give 4f as a red solid. Obtained:
0.155 g (61% yield). Anal. Calcd for [C24H21ClNPRu] (490.93):
C, 58.72; H, 4.31; N, 2.85. Found: C, 58.53; H, 4.08; N, 2.78. IR:
1295 (νPdN) cm-1; 3200 (νN-H) cm-1. MS (MALDIþ): 491
(65%) [M]þ. 1H NMR (CDCl3): δ 0.90 (s br, 1H, NH), 5.14 (s,
6H, η6-C6H6), 6.95-6.99 (m, 2H, H3 þ H4, C6H4), 7.26 (m, 1H,
H5, C6H4), 7.39 (m, 2H, Hm, PPh), 7.48-7.57 (m, 5H, Hm þ Hp
þ Ho, PPh), 7.64 (m, 1H, Hp, PPh), 7.75 (m, 2H, Ho, PPh), 8.19
3
3
2
1H, CH2, JHP=17.2), 4.76 (dd, 1H, CH2, JHP=9.6, JHH
=
17.2), 5.21 (s, 6H, η6-C6H6), 7.11 (d, 1H, H3, C5H4N, 3JHH=7.6),
3
7.33 (t, 1H, H5, C5H4N, JHH=6.4), 7.48-7.52 (m, 6H, Hm,
3
4
(dd, 1H, H6, C6H4, JHH =7.6, JHH =1.0). 13C{1H} NMR
PPh3), 7.58-7.63 (m, 9H, Hp þ Ho, PPh3), 7.73 (td, 1H, H4,
C5H4N, 3JHH=6.4, 4JHH=1.2), 8.91 (d, 1H, H6, C5H4N, 3JHH
5.2). 13C{1H} NMR (CDCl3): δ 61.1 (s, CH2), 84.8 (s, η6-C6H6),
119.9 (s, C3, C5H4N), 124.9 (s, C5, C5H4N), 126.8 (d, Ci, PPh3,
1JPC=98.0), 129.1 (d, Cm, PPh3, 3JPC=12.4), 133.5 (d, Cp, PPh3,
4JPC=2.6), 134.3 (d, Co, PPh3, 2JPC=10.0), 139.0 (s, C4, C5H4N),
154.6 (s, C6, C5H4N), 163.3 (d, C2, C5H4N, 3JPC =8.6). 31P{1H}
NMR (CDCl3): δ 44.64.
=
(CDCl3): δ 84.5 (s, η6-C6H6), 121.7 (d, C4, C6H4, 3JPC = 13.8),
3
2
130.1 (d, Cm, PPh2, JPC = 12.9), 130.8 (d, C3, C6H4, JPC
20.2), 131.4 (d, Ci, PPh2, 1JPC=88.3), 133.6 (d, C5, C6H4, 4JPC
2.9), 133.5 (d, Co, PPh2, 2JPC=10.5), 135.5 (d, Cp, PPh2, 4JPC
=
=
=
=
2.9), 139.8 (d, C6, C6H4, 3JPC=14.0), 177.2 (d, C1, C6H4, 2JPC
21.1). The signal due to C2 (C6H4) was not observed. 31P{1H}
NMR (CDCl3): δ 51.19.
Synthesis of [(η6-C6H6)Ru{(C6H4)-2-Ph2PdNPh-K-C,N}Cl],
4e. To a suspension of [(η6-C6H6)RuCl(μ-Cl)]2 (0.059 g, 0.12
mmol) in CH2Cl2 (20 mL) was added compound 3e (0.107 g,
0.12 mmol). The resulting suspension was stirred at room
temperature for 3 days, then filtered through Celite. The red
solution was evaporated to small volume (≈1-2 mL). The
residue was treated with Et2O (20 mL). Subsequent stirring
promoted the precipitation of a red solid, which was filtered,
washed with Et2O (15 mL), dried in vacuo, and identified as 4e.
Obtained: 0.080 g (59% yield). Anal. Calcd for [C30H25ClN-
PRu] (567.02): C, 63.55; H, 4.44; N, 2.47. Found: C, 63.10; H,
4.21; N, 2.18. IR: 1287 (νPdN) cm-1. MS (MALDIþ): 567 (60%)
[M]þ. 1H NMR (CDCl3): δ 5.17 (s, 6H, η6-C6H6), 6.85-6.95 (m,
2H, H3 þ H4, C6H4), 7.02-7.11 (m, 3H, Hm þ Hp, NPh), 7.13 (t,
2H, Ho, NPh, 3JHH=7.1), 7.27 (m, 1H, H5, C6H4), 7.62-7.69 (m,
6H, Hm þ Hp, PPh2), 7.84 (m, 4H, Ho, PPh2), 8.25 (d, 1H, H6,
C6H4, 3JHH=6.9). 13C{1H} NMR (CDCl3): δ 85.6 (s, η6-C6H6),
120.3 (d, Ci, PPh2, 1JPC=102.1), 123.1 (d, C4, C6H4, 3JPC=14.2),
124.4 (s, NPh), 128.2 (s, NPh), 129.2 (d, C3, C6H4, 2JPC=20.7),
129.5 (s, Co, NPh), 130.2 (d, Cm, PPh2, 3JPC=13.5), 131.05 (d, C5,
Synthesis of [(η6-p-cymene)Ru{(C6H4)-2-Ph2PdNH-K-C,
N}Cl], 5f. Compound 5f was prepared following the same
synthetic method as that described for 4e. Therefore [(η6-p-
cymene)RuCl(μ-Cl)]2 (0.168 g, 0.27 mmol) was reacted with 3f
(0.245 g, 0.27 mmol) in 20 mL of CH2Cl2 to give 5f as a red solid.
Obtained: 0.130 g (44% yield). Anal. Calcd for [C28H29-
ClNPRu] (547.02): C, 61.48; H, 5.34; N, 2.56. Found: C,
61.13; H, 5.17; N, 2.39. IR: 1279 (νPdN) cm-1; 3140 (νN-H
)
cm-1. MS (MALDIþ): 547 (45%) [M]þ. 1H NMR (CDCl3): δ
1.05-1.11 (m, 6H, Me2-cymene), 1.24 (d, 1H, NH, 2JHP=6.9),
1.74 (s, 3H, Me-cymene), 2.55 (m, 1H, CH-cymene), 4.48, 4.96,
5.12, 5.29 (4s br, 4H, C6H4-cymene), 6.94-7.00 (m, 2H, H3 þ
H4, C6H4), 7.23-7.83 (m, 11H, H5, C6H4 þ Hm þ Hp þ Ho,
PPh2), 8.16 (dd, 1H, H6, C6H4, 3JHH=7.7, 4JHH=1.0). 31P{1H}
NMR (CDCl3): δ 51.46.
Synthesis of [C6H4PPh2NPh-C(Et)dC(Et)-3,4](PF6), 6. To a
solution of complex 5e (0.138 g, 0.22 mmol) in MeOH (20 mL))
were added KPF6 (0.050 g, 0.27 mmol) and 3-hexyne (31 μL,
0.27 mmol, and the resulting red solution was stirred at room
temperature for 1 h. After this time CuBr2 (0.110 g, 0.50 mmol)

648 Organometallics, Vol. 30, No. 3, 2011
Aguilar et al.
was added, and a black suspension was formed in a few seconds.
The stirring was maintained at the same temperature for 15 h.
After the reaction time the solvent was evaporated to dryness,
and the black residue was extracted twice with CH2Cl2 (2 ꢀ 20
mL). The solid was discarded, and the clear filtered yellow
solution was evaporated to a small volume (≈1 mL) and treated
with Et2O (15 mL), promoting the precipitation of 6 as a yellow
solid. This solid was filtered, washed with additional Et2O (10
mL), and dried in vacuo. Obtained: 0.085 g (66% yield). Anal.
Calcd for [C30H29F6NP2] (579.50): C 62.18; H, 5.04; N, 2.42.
Found: C 62.35; H, 4.80; N, 2.37. IR: 1302 (νPdN) cm-1. MS
(MALDI þ): 434 (100%) [M - PF6]þ. 1H NMR (CDCl3): δ 0.97
(t, 3H, Me, 3JHH=7.0), 1.04 (t, 3H, Me, 3JHH=6.9), 2.40 (q, 2H,
CH2, 3JHH=7.0), 2.77 (q, 2H, CH2, 3JHH=7.0), 7.04 (m, 2H, Ho,
NPh), 7.24-7.27 (m, 4H, Hm þ Hp, NPh þ H3, C6H4),
7.42 (m, 1H, H4, C6H4), 7.60-7.70 (m, 8H, Hm þ Ho, PPh2),
7.84-7.93 (m, 3H, H6, C6H4 þ Hp, PPh2), 7.99 (m, 1H, H5,
C6H4). 13C{1H} NMR (CDCl3): δ 13.9 (s, Me), 22.7 (s, CH2),
14.7 (s, Me), 24.5 (s, CH2), 96.8, 102.2 (2s, CdC), 112.9 (d, Ci,
7.33-7.58 (m, 9H, 2H, C6H4 þ 7H, Ar), 7.58-7.88 (m, 6H, 1H,
C6H4 þ 5H, Ar). 13C{1H} NMR (CDCl3): δ 110.7 (d, Ci, PPh2,
1
1JPC=100.4), 117.6 (d, C1, C6H4, JPC=103.6), 120.3 (s, Ar),
124.5 (s, Ar), 127.1 (s, Ar), 127.6 (d, Ar, JPC=1.5), 127.8 (s, Ar),
127.8 (s, Ar), 128.4-128.6 (2 CH overlapped, C6H4 þ Ar), 129.0
(d, Ar, JPC=27.5), 129.6 (d, Ar, JPC=2.1), 130.6 (d, Cm, PPh2,
3JPC=13.0), 130.9 (s, Ar), 131.3 (d, C6H4, JPC=11.1), 131.4 (s,
Ar), 131.9 (s, Ar), 132.1 (d, C6H4, JPC = 9.8), 133.1 (s, Ar), 134.6
(Co, PPh2, 2JPC=11.0), 135.7 (d, C6H4, JPC=2.0), 136.7 (d, Cp,
PPh2, 4JPC=2.7). Signals due to the carbons CdC, C1, NPh, Ci,
Ph, and C2, C6H4 were not found. 31P{1H} NMR (CDCl3): δ
34.97.
Synthesis of [C6H4PPh2NPh-C(Me)dC(Ph)-3,4](PF6), 9.
Compound 9 was prepared following the same experimental
procedure as that described for 6. Therefore, 5e (0.171 g, 0.27
mmol) was reacted with 1-phenyl-1-propyne (Ph-CtC-Me) (41
μL, 0.33 mmol), KPF6 (0.06 g, 0.33 mmol), and CuBr2 (0.135 g,
0.60 mmol) in MeOH (30 mL) to give 9 as an orange solid.
Obtained: 0.096 g (58% yield). Anal. Calcd for [C33H27F6NP2]
(613.51): C, 64.60; H, 4.44; N, 2.28. Found: C, 64.90; H, 4.31; N,
2.17. IR: 1295 (νPdN) cm-1. MS (MALDIþ): 468 (100%) [M -
PF6]þ. 1H NMR (CDCl3): δ 2.27 (s, 3H, Me), 6.94-7.03 (m, 5H,
NPh), 7.23-7.33 (m, 5H, Ph), 7.53 (m, 1H, H5, C6H4),
7.76-7.88 (m, 11H, H6, C6H4 þ Hm þ Hp þ Ho, PPh2),
8.04-8.10 (m, 2H, H3 þ H4, C6H4). 13C{1H} NMR (CDCl3):
1
1
PPh2, JPC= 100.5), 116.9 (d, C1, C6H4, JPC = 104.0), 126.1
3
2
(d, C3, C6H4, JPC = 9.8), 127.2 (d, C2, C6H4, JPC =10.0),
128.7 (s, Cp, NPh), 129.3 (d, Co, NPh, 3JPC = 1.3), 129.6 (d, C6,
C6H4, 2JPC=13.9), 130.4 (s, Cm, NPh), 130.9 (d, Cm, PPh2, 3JPC
=
3
13.6), 131.8 (d, C5, C6H4, JPC = 11.2), 135.2 (d, Co, PPh2,
2JPC=11.6), 136.2 (d, C4, C6H4, 4JPC = 2.0), 136.6 (d, Cp, PPh2,
4JPC = 2.7), 139.3 (s, Ci, NPh). 31P{1H} NMR (CDCl3):
δ 33.01.
1
δ 18.3 (s, Me), 111.7 (d, Ci, PPh2, JPC = 99.3), 117.1 (d, C1,
C6H4, 1JPC=104.1), 120.8 (d, C2, C6H4, 2JPC=9.1), 126.9 (d, C3,
C6H4, 3JPC=9.7), 127.8 (d, Cm, NPh, 3JPC=1.6), 128.6 (s, Ph),
129.1 (d, Co, NPh, 3JPC = 2.2), 129.3 (s, Cp, NPh), 129.5 (d, Co,
Synthesis of [C6H4PPh2NPh-C(CO2Me)dC(CO2Me)-3,4]-
(PF6), 7. Compound 7 was prepared following the same experi-
mental procedure as that described for 6. Therefore, 5e (0.150 g,
0.24 mmol) was reacted with MeO2C-CtC-CO2Me (35 μL, 0.28
mmol), KPF6 (0.053 g, 0.28 mmol), and CuBr2 (0.118 g, 0.53
mmol) in MeOH (30 mL) to give 7 as a yellow solid. Obtained:
0.051 g (33% yield). Anal. Calcd for [C30H25F6NO4P2] (639.46):
C, 56.35; H, 3.94; N, 2.19. Found: C, 56.50; H, 3.75; N, 2.10. IR:
1670 (νCdO), 1631(νCdO), 1287 (νPdN) cm-1. MS (MALDIþ):
494 (100%) [M - PF6]þ. 1H NMR (CDCl3): δ 3.21 (s, 3H,
5
2
Ph, JPC=1.2), 129.9 (d, C6, C6H4, JPC=13.7), 130.7 (d, Cm,
PPh2, 3JPC=13.7), 130.9 (s, Ph), 131.3 (d, C5, C6H4, 3JPC=11.4),
133.9 (d, CdC, 3JPC=4.7), 134.7 (d, Co, PPh2, 2JPC=11.7), 136.1
(d, C4, C6H4, 4JPC=2.2), 136.5 (d, Cp, PPh2, 4JPC=2.9), 137.1 (d,
4
2
C1, Ph, JPC = 1.6), 137.4 (s, CdC), 140.6 (d, Ci, NPh, JPC
=
5.3). 31P{1H} NMR (CDCl3): δ 33.86.
X-ray Crystallography. Crystals of adequate quality for X-ray
measurements were grown by slow diffusion of Et2O into
CH2Cl2 solutions of the crude products at 25 °C. A single crystal
of each compound was mounted at the end of a quartz fiber in a
random orientation, covered with magic oil, and placed under
the cold stream of nitrogen. Data collection was performed at
room temperature or low temperature (150 K) on an Oxford
Diffraction Xcalibur2 diffractometer using graphite-monochro-
mated Mo KR radiation (λ = 0.71073 A). A hemisphere of data
was collected in each case based on three ω-scan or j-scan runs.
The diffraction frames were integrated using the program
CrysAlis RED,17 and the integrated intensities were corrected
for absorption with SADABS.18 The structures were solved and
developed by Patterson and Fourier methods.19 The structures
were refined to Fo2, and all reflections were used in the least-
squares calculations.20
3
OMe), 3.37 (s, 3H, OMe), 6.91 (d, 2H, Ho, NPh, JHH=7.6),
7.03-7.07 (m, 2H, Hp, NPh þ H3, C6H4), 7.21-7.28 (m, 3H,
3
Hm, NPh þ H4, C6H4), 7.35 (d, 1H, H6, C6H4, JHH=7.0),
7.71-7.50 (m, 7H, H5, C6H4 þ Hm þ Hp, PPh2), 7.64-7.74
(m, 4H, Ho, PPh2). 13C{1H} NMR (CDCl3): δ 51.0 (s, OMe),
52.0 (s, OMe), 120.6 (s, C4, C6H4), 120.9 (s, Co, NPh), 124.2 (s,
Cp, NPh), 126.9 (d, C6, C6H4, 2JPC = 13.0), 128.2 (d, Cm, PPh2,
3JPC = 11.0), 129.1 (s, Cm, NPh), 131.4 (d, Cp, PPh2, 4JPC=2.8),
132.2 (d, Co, PPh2, 2JPC=9.6), 133.2 (d, C3, C6H4, 3JPC=10.0),
133.9-134.2 (m, Ci, PPh2 þ Ci, C6H4), 135.0 (d, C5, C6H4, 3JPC
=12.0), 139.8 (d, C2, C6H4, 2JPC=8.0), 139.9, 147.1 (2s, CdC),
164.1, 169.0 (2s, CdO). 31P{1H} NMR (CDCl3): δ 29.52.
Synthesis of [C6H4PPh2NPh-C(Ph)dC(Ph)-3,4](PF6) 8.
Compound 8 was prepared following the same experimental
procedure as that described for 6. Therefore, 5e (0.171 g, 0.27
mmol) was reacted with diphenylacetylene (Ph-CtC-Ph) (0.06
g, 0.33 mmol), KPF6 (0.06 g, 0.33 mmol), and CuBr2 (0.135 g,
0.60 mmol) in MeOH (30 mL) to give 8 as an orange solid.
Obtained: 0.103 g (56% yield). Anal. Calcd for [C38H29F6NP2]
(675.58): C, 67.56; H, 4.33; N, 2.07. Found: C, 67.44; H, 4.24; N,
1.99. IR: 1308 (νPdN) cm-1. MS (MALDIþ): 530 (100%) [M -
PF6]þ. 1H NMR (CDCl3): δ 5.37 (m, 2H, Ph), 5.50 (m, 2H, Ph),
6.94-7.07 (m, 9H, 1H, Ph þ 8H, Ar), 7.20 (m, 1H, C6H4),
Acknowledgment. Funding from Ministerio de Ciencia
ꢀ
e Innovacion (Project CTQ2008-01784, Spain) and
Gobierno de Aragon (PI071-09) is gratefully acknowledged.
ꢀ
Supporting Information Available: CIF files giving complete
data collection parameters for 2a, 5e, and 4f. This material
is available free of charge via the Internet at http://pubs.acs.org.
(17) CrysAlis RED, Version 1.171.27p8; Oxford Diffraction Ltd., 2005.
(18) Sheldrick, G. M. SADABS: Empirical absorption correction
(19) Sheldrick, G. M. SHELXS-86. Acta Crystallogr. 1990, A46, 467.
(20) Sheldrick, G. M. SHELXL-97. Acta Crystallogr. 2008, A64, 112.
€
program; Gottingen University, 1996.