Imination reactions of free and coordinated 2-diphenylphosphino-1-phenyl- phospholane: Access to regioisomeric ruthenium(ii) complexes containing novel iminophosphorane-phosphine ligands

Article abstract of DOI:10.1039/b606781f

In this work, selective monoimination reactions of free and Ru-coordinated 2-diphenylphosphino-1-phenyl-phospholane with diphenylphosphoryl azide or 4-azido-2,3,5,6-tetrafluorobenzonitrile are described. Following this approach, a large variety of neutral and cationic mono- and dinuclear (η⁶- arene)-ruthenium(ii) complexes containing regioisomeric iminophosphorane- phosphine ligands could be prepared and, in some cases, structurally characterized by means of X-ray diffraction methods. The catalytic activity of these ruthenium complexes, both in racemic or enantiomerically pure form, in Diels-Alder cycloaddition reactions is also presented. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.

Full text of DOI:10.1039/b606781f

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/njc | New Journal of Chemistry
Imination reactions of free and coordinated 2-diphenylphosphino-1-
phenyl-phospholane: Access to regioisomeric ruthenium(II) complexes
containing novel iminophosphorane–phosphine ligands
a
a
b
a
´
´
az-Alvarez, Pascale Crochet,* Maria Zablocka,* Victorio Cadierno,
Alba E. Dı
Carine Duhayon, Jose Gimeno and Jean-Pierre Majoral*
c
a
c
´
Received (in Montpellier, France) 12th May 2006, Accepted 23rd June 2006
First published as an Advance Article on the web 26th July 2006
DOI: 10.1039/b606781f
In this work, selective monoimination reactions of free and Ru-coordinated 2-diphenylphosphino-
1-phenyl-phospholane with diphenylphosphoryl azide or 4-azido-2,3,5,6-tetrafluorobenzonitrile are
described. Following this approach, a large variety of neutral and cationic mono- and dinuclear
(Z6-arene)–ruthenium(II) complexes containing regioisomeric iminophosphorane–phosphine
ligands could be prepared and, in some cases, structurally characterized by means of X-ray
diffraction methods. The catalytic activity of these ruthenium complexes, both in racemic or
enantiomerically pure form, in Diels–Alder cycloaddition reactions is also presented.
ligands, which are mainly derived from the symmetrical dipho-
Introduction
sphines Ph2P–X–PPh2 (X = CH2, (CH2)2, 1,2-C6H4, NR) via
selective monoimination,5 are: olefin hydrogenation (Rh and
Ir complexes)6 and oligomerization (Ni complexes),7 methanol
carbonylation (Rh, Ni and Co complexes),8 Sonogashira-type
coupling (Pd complexes),9 allylic alkylation (Pd and Rh com-
plexes)10 and transfer hydrogenation of ketones (Ru com-
plexes).11
The coordination chemistry of heterodifunctional chelating
ligands has received considerable attention during recent
decades, the continuous efforts in the design of new ligands
being justified by their potential application in homogeneous
catalysis. In particular, heterobidentate phosphines are widely
used in catalysis as hemilabile ligands capable of generating
open coordination sites on the metal for substrate binding.1
Moreover, they can also control the reactivity of the metal
sites owing to the different steric and electronic properties of
the donor groups. Mixed bidentate P,N-donor ligands, such as
phosphine–imines or phosphine–oxazolines, are probably the
most attractive and widely used heterodifunctional ligands in
catalysis, leading to impressive results in terms of both stereo/
enantio-selectivity and reactivity.2
Some years ago, some of us reported a straightforward
synthetic route to non-symmetrical a-diphosphines 2 through
the hydrozirconation of readily available dihydrophosphole
1,12 and subsequent transmetallation of the resulting zirco-
nated species with chlorophosphines (see Chart 1).13 Follow-
ing the same approach, enantiopure derivatives (SPSC)-2 can
be easily prepared starting from the optically active dihydro-
phosphole (RP)-1.13b
Iminophosphoranes, R3PQNR0 (nitrogen analogues of
phosphorus ylides), have found widespread application in
organic synthesis3 and proved to be versatile nitrogen-donor
ligands for transition metals.4 The combination of a phosphine
function with an iminophosphorane unit within the same
molecule leads to an almost unexploited family of bidentate
P,N-donor ligands, i.e. the iminophosphorane–phosphines
R2P–X–P(QNR0)R2,5 structurally related to the well-known
diphosphine–monoxides.1c As far as we are aware, the only
catalytic applications reported to date for these types of
Taking into account that the ruthenium chemistry of imi-
nophosphorane–phosphines has been scarcely investigated,11
and the growing interest in the design of ruthenium catalysts
for organic synthesis,14 we decided to explore the potential of
our a-diphosphines 2 as precursors of these types of ligand and
complex. Thus, in this paper, we report the selective synthesis
of novel iminophosphorane–phosphines A (see Chart 2),
derived from the a-diphosphine 2-diphenylphosphino-1-phe-
nyl-phospholane, and their coordination to an (Z6-arene)–
ruthenium(II) fragment (complexes B). Remarkably, the re-
gioisomeric species D could also be readily prepared upon
a
´
Departamento de Quımica Organica e Inorganica, Instituto
Universitario de Quımica Organometalica ‘‘Enrique Moles’’ (Unidad
´
´
´
´
´
Asociada al CSIC), Facultad de Quımica, Universidad de Oviedo,
E-33071 Oviedo, Spain. E-mail: pascale@fq.uniovi.es
Fax: +34 985 103 446; Tel: +34 985 102 985
b Centre of Molecular and Macromolecular Studies, The Polish
Academy of Sciences, Sienkiewicza 112, 90363 yo´d$, Poland.
E-mail: zabloc@bilbo.cbmm.lodz.pl; Fax: +48 426 847 126
Tel: +48 426 803 217
c Laboratoire de Chimie de Coordination CNRS, UPR8241, 205 route
de Narbonne, 31077 Toulouse Cedex 4, France.
E-mail: majoral@lcc-toulouse.fr; Fax: +33 561 553 003
Tel: +33 561 333 123
Chart 1 Zirconium-mediated synthesis of a-diphosphines 2.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1295–1306 | 1295

View Article Online
Chart 2 Access to the regioisomeric Ru(II) complexes B and D.
Scheme 1 Mono- and diimination reactions of 2-diphenylphosphino-
1-phenyl-phospholane (2).
initial coordination of 2 to the metal (species C). Reactivity
studies directed to the chelation of the novel iminophospho-
rane–phosphine ligands on these Ru(II) complexes, as well as
their catalytic activity in Diels–Alder cycloadditions, are also
reported.
NMR, a doublet of doublets resonance at 36.6–39.0 ppm
(JCP = 54.7 and 24.3 Hz (3a), 75.7 and 24.4 Hz (3b)).
Coordination of the iminophosphorane–phosphine ligands 3a–b
to an (g6-arene)–ruthenium(II) fragment
Results and discussion
The ability of the novel iminophosphorane–phosphines 3a–b
to act as mono- and bidentate ligands has been explored using
the readily available ruthenium(II) chloro-bridged dimer
[{RuCl(m-Cl)(Z6-p-cymene)}2] as the starting material.18 This
dimeric compound was chosen as the precursor due to its
versatile reactivity towards polyfunctional ligands.19 Thus, we
have found that the treatment of [{RuCl(m–Cl)(Z6-p-cym-
ene)}2] with ca. 2.5 equivalents of 3a–b, in dichloromethane
at room temperature, results in the selective formation of the
monomeric derivatives 5a–b (see Scheme 2), which have been
isolated as air-stable orange solids in good yields (80–82%).
The characterization of complexes 5a–b was achieved by
means of standard spectroscopic techniques (IR and multi-
nuclear NMR) as well as elemental analyses, all data being
fully consistent with the proposed formulations (see the Ex-
perimental section for details). In particular, the monohapto
coordination of 3a–b through the diphenylphosphino group is
strongly supported by the 31P{1H} NMR spectra, which shows
a remarkable downfield shift of the Ph2P signals (ca. dP = 23
ppm, Dd = 35 ppm) with respect to those of the free ligands.
In contrast, a slight shielding is observed in the resonances
corresponding to the iminophosphorane PhPQN units (5a,
Synthesis of the iminophosphorane–phosphine ligands 3a–b
In general, iminophosphoranes are best prepared through one
of two major routes, namely: (i) the reaction of azides with
phosphines (the Staudinger reaction)15,16 and (ii) the reaction
of phosphine dibromides (R3PBr2) with primary amines,
followed by treatment with a base (the Kirsanov reaction).16,17
As illustrated in Scheme 1, we employed the former method to
prepare the novel iminophosphorane–phosphine ligands 3a–b,
which have been isolated as air-stable solids in 90% and 75%
yield, respectively, after stoichiometric reaction of racemic 2-
diphenylphosphino-1-phenyl-phospholane (2) with diphenyl-
phosphoryl azide or 4-azido-2,3,5,6-tetrafluorobenzonitrile, in
THF at room temperature. Under these conditions, mono-
imination of 2 takes place exclusively at the more basic dialkyl-
P-phospholane phosphorus atom, the oxidation of the Ph2P
unit being observed only when both an excess of azide and
longer reactions times (1–6 d vs. 0.5–2 h) are employed. In this
manner, the bis(iminophosphorane) derivatives 4a–b could
also be cleanly prepared and isolated in good yields
(77–82%; Scheme 1).
The characterization of iminophosphorane–phosphines
3a–b was straightforward following their analytical and spec-
troscopic data (details are given in the Experimental section).
In particular, the 31P{1H} NMR spectra are very informative,
showing a strong downfield of the phospholane PhP signal
(dP = 44.0 (3a) and 52.0 (3b) ppm) with respect to that shown
by the diphosphine precursor 2 (dP = ꢁ4.5 ppm) and the Ph2P
resonance remaining almost unchanged (dP = ꢁ13.9 (3a) and
ꢁ10.9 (3b) vs. ꢁ13.5 (2) ppm). 1H and 13C{1H} NMR spectra
also exhibit signals in accordance with the proposed formula-
tions, the most significant features being those concerning the
1
methynic PCHP group of the ligands: (i) in the H NMR, an
unresolved multiplet at 3.42–4.15 ppm, and (ii) in the 13C{1H}
Scheme 2 The monodentate coordination of iminophosphorane–
phosphines 3a–b.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
1296 | New J. Chem., 2006, 30, 1295–1306

View Article Online
Fig. 1 CAMERON-type view of the structure of complex 5a, show-
ing the crystallographic labelling scheme. Hydrogen atoms are omitted
for clarity. Thermal ellipsoids are drawn at 30% probability level.
Selected bond lengths (A) and angles (1): Ru–C* = 1.71; Ru–Cl(1) =
2.4142(15); Ru–Cl(2) = 2.4083(14); Ru–P(1) = 2.3556(14); P(1)–
C(13) = 1.875(6); C(13)–C(14) = 1.541(9); C(14)–C(15) = 1.497(10);
C(15)–C(16) = 1.509(14); C(13)–P(2) = 1.830(6); C(16)–P(2) =
1.808(9); P(2)–N(1) = 1.577(6); N(1)–P(3) = 1.573(5); P(3)–O(1) =
1.452(6); P(3)–O(2) = 1.589(5); P(3)–O(3) = 1.582(5); C*–Ru–Cl(1) =
126; C*–Ru–Cl(2) = 128; C*–Ru–P(1) = 128; Cl(1)–Ru–Cl(2) =
Scheme 3 Reactivity of complexes 5a–b towards AgSbF6.
eoselective manner (the Ru atom becomes a stereogenic
center), a non-separable mixture of two diastereoisomers being
obtained in ca. 60 : 40 ratio. The k2-P,O-coordination of the
N-phosphorylated ligand 3a in complex 6 is fully supported by
the 31P{1H} NMR data. Thus, as a common trend for both
85.20(5); Cl(1)–Ru–P(1)
= 89.81(5); Cl(2)–Ru–P(1) = 85.91(5);
Ru–P(1)–C(13) = 115.2(2); P(1)–C(13)–P(2) = 124.2(4); P(1)–C(13)–
C(14) = 113.2(4); C(13)–C(14)–C(15) = 107.8(6); C(14)–C(15)–C(16)
= 110.4(7); C(15)–C(16)–P(2) = 107.0(5); C(13)–P(2)–C(16) = 95.4(4);
C(13)–P(2)–N(1) = 111.1(3); C(16)–P(2)–N(1) = 114.8(4); P(2)–N(1)–
P(3) = 128.8(4); N(1)–P(3)–O(1) = 122.3(3); N(1)–P(3)–O(2) =
101.7(3); N(1)–P(3)–O(3) = 106.5(3); O(1)–P(3)–O(2) = 114.3(3);
O(1)–P(3)–O(3) = 106.9(3); O(2)–P(3)–O(3) = 103.6(3). C* = centroid
of the p-cymene ring (C(35), C(36), C(37), C(38), C(39), C(40)).
diastereoisomers,
a remarkable downfield shift in the
(PhO)2P(QO) group resonance (ca. Dd = 15 ppm), with
respect to that of the parent compound 5a (i.e. dP = 8.7
(major) and 6.2 (minor) vs. ꢁ7.8 ppm), is observed. The
chemical shifts of the Ph2P and PhPQN units are almost
unaffected by the ring closure (Dd = 3 ppm), ruling out the
formation of a five-membered k2-P,N-chelate complex. It
should be noted that the preference shown by the iminopho-
sphorane–phosphine 3a for the k2-P,O- vs. k2-P,N-coordina-
tion is in complete accord with the behaviour recently
described by some of us for the closely related ligands
Ph2PCH2P{QNP(QO)(OR)2}Ph2 (R = Et, Ph), from which
dP = 41.6 ppm, Dd = ꢁ2 ppm; 5b, dP = 44.1 ppm, Dd = ꢁ8
ppm) and the phosphoryl (PhO)2PQO group (5a, dP = ꢁ7.8
ppm, Dd = ꢁ3 ppm). X-Ray diffraction studies on 5a unequi-
vocally confirmed the structure of these complexes. A view of
the molecule is shown in Fig. 1 and reveals the classic
pseudooctahedral three-legged piano-stool geometry around
the metal, the values of the interligand angles Cl(1)–Ru–Cl(2),
Cl(1)–Ru–P(1) and Cl(2)–Ru–P(1), and those between the
centroid of the p-cymene ring C* and the legs, being typical
of a pseudo-octahedron. We also note that, as previously
observed in other species containing the N-phosphorylated
iminophophorane unit –PQN–P(QO)(OPh)2,11b,20 the lengths
of the formal single and double PN bonds were found to be
almost identical (P(2)–N(1) = 1.577(6) A vs. N(1)–P(3) =
1.573(5) A). This fact clearly reflects the extensive electronic
delocalization of the nitrogen lone pair across the PQN–PQO
framework in this molecule.
the k2-P,O-complexes
E (Chart 3) are also selectively
formed.11b
Surprisingly, the chelate k2-P,N-coordination of the imino-
phosphorane–phosphine 3b has been not observed after treat-
ment of the neutral derivative 5b with AgSbF6. Instead, the
dicationic dinuclear species 7, in which 3b is acting as a
bridging ligand between two [RuCl(Z6-p-cymene)] metallic
fragments, is exclusively formed (Scheme 3). Complex 7, which
has been isolated as an air-stable orange solid in 90% yield,
In order to achieve the chelation of iminophosphorane–
phosphines 3a–b, the reactivity of neutral complexes 5a–b
towards silver hexafluoroantimonate has been studied. Thus,
we have found that the treatment of 5a with a stoichiometric
amount of AgSbF6 in dichloromethane at room temperature
generates the cationic derivative 6, which is readily formed via
selective intramolecular O-coordination of the phosphoryl
group (Scheme 3). Examination of the NMR data of 6 reveals
that the chelate ring formation does not proceed in a diaster-
Chart 3 Structure of complexes E and F.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1295–1306 | 1297

View Article Online
Chart 4 Structure of the iminophosphorane–phosphine ligands G
and the diphosphine–monoxide H.
the literature for other nitrile–ruthenium(II) complexes.24 The
iminophosphorane P–N bond distance (P(2)–N(2)
=
1.570(15) A) is also in accord with those observed for related
uncoordinated R3PQN-4-C6F4CN moieties.21,23b
Fig. 2 CAMERON-type view of the structure of complex 7 showing
the crystallographic labelling scheme. Unlabelled atoms are generateꢁd
by a crystallographic center of symmetry. Hydrogen atoms and SbF6
anions are omitted for clarity. Thermal ellipsoids are drawn at 30%
probability level. Selected bond lengths (A) and angles (1): Ru–C* =
1.72; Ru–Cl(1) = 2.390(5); Ru–P(1) = 2.376(5); Ru–N(1) = 2.043(14);
N(1)–C(1) = 1.16(2); C(1)–C(2) = 1.41(2); C(5)–N(2) = 1.39(2); P(2)–
N(2) = 1.570(15); P(2)–C(36) = 1.838(17); P(2)–C(39) = 1.867(16);
C(36)–C(37) = 1.58(2); C(37)–C(38) = 1.55(2); C(38)–C(39) = 1.53(2);
C(39)–P(1) = 1.872(16); C*–Ru–Cl(1) = 123; C*–Ru–P(1) = 129; C*–
Ru–N(1) = 126; Cl(1)–Ru–N(1) = 86.8(4); Cl(1)–Ru–P(1) = 92.11(15);
P(1)–Ru–N(1) = 86.1(4); Ru–N(1)–C(1) = 171.5(14); N(1)–C(1)–C(2)
= 178.0(19); P(2)–N(2)–C(5) = 134.2(12); N(2)–P(2)–C(36) = 116.8(8);
N(2)–P(2)–C(39) = 119.8(7); C(36)–P(2)–C(39) = 95.8(7); C(36)–C(37)–
C(38) = 109.1(14); C(37)–C(38)–C(39) = 105.4(13); C(38)–C(39)–
+P(2) = 102.5(10); C(38)–C(39)–P(1) = 112.4(11); P(1)–C(39)–P(2)
= 123.0(8); Ru–P(1)–C(39) = 114.2(5). C* = centroid of the p-
cymene ring (C(8), C(9), C(10), C(11), C(12), C(13)). Symmetry code
related to moiety: 2 ꢁ x, 1 ꢁ y, 2 ꢁ z.
Finally, it is also interesting to note that the diastereoisomer
shown in Fig. 2, the major form present in solution, is a
centrosymmetric dimer that shows inverted configurations
for the labelled and unlabelled metallic fragments, i.e.
S
Ru(1)RC(39)SP(2) and RRuSCRP, respectively.25 This seems to
indicate that the dimerization process of the 16eꢁ intermediate
[RuCl(k1-P-3b)(Z6-p-cymene)][SbF6] takes place with chiral
self-recognition.26 Taking into account that the racemic a-
diphosphine precursor 2 is exclusively composed of the SPSC
and RPRC enantiomers,13 and assuming that formation of 3b
occurs with retention of configuration,27 we propose an
RRuRCSPSRuSCRP configuration for the minor diastereo-
isomer present in solution.
Imination reactions of coordinated 2-diphenylphosphino-1-
phenyl-phospholane: Access to the (g6-arene)–ruthenium(II)
complexes 9–11
As discussed above, the Staudinger reaction of 2-diphenylpho-
sphino-1-phenyl-phospholane (2) with one equivalent of azide
takes place selectively on the endocyclic P-phospholane phos-
phorus atom, allowing the high-yield synthesis of the imino-
phosphorane–phosphines 3a,b (Scheme 1). Remarkably, the
regioisomeric ligands G, resulting from the selective imination
of the diphenylphosphino group (Chart 4), can also be gener-
ated upon initial coordination of 2 to ruthenium.
results from the competitive dimerization vs. chelate ring
formation of the cationic 16eꢁ intermediate [RuCl(k1-P-
3b)(Z6-p-cymene)][SbF6]. Formation of 7 contrasts with the
high-yield synthesis of the mononuclear species [RuCl(k2-P,N-
Ph2PCH2P{QN-4-C6F4CN}Ph2)(Z6-p-cymene)][SbF6]
(F;
Chart 3), starting from the closely related ligand Ph2PCH2P
{QN-4-C6F4CN}Ph2, recently reported by us.21 We also note
that, although some ruthenium complexes containing N-co-
ordinated RC6F4CN (R = F, CN) ligands are known,22 the
coordination of the nitrile unit of 3b in the dinuclear complex 7
can be considered as rather unusual.23
The 1H, 31P{1H} and 19F{1H} NMR spectroscopic data
obtained for complex 7 suggest that, in solution, it exists as a
mixture of two diastereoisomers in ca. 75 : 25 ratio. The
nature of the major isomer has been unambiguously confirmed
by means of X-ray diffraction. The molecular structure is
depicted in Fig. 2; selected bond distances and angles are
listed in the caption. The two metallic moieties exhibit the
expected pseudooctahedral three-legged piano-stool geometry,
the coordination sphere around each ruthenium atom consist-
ing of the p-cymene ring, one chloride, the PPh2 group of one
of the ligands, and the nitrile unit of a second ligand. The latter
Construction of the ligands G involves the imination of the
free Ph2P unit in the neutral (Z6-arene)–ruthenium(II) complex
8 (Scheme 4). This compound can be obtained in high-yield
(92%) by treatment of a dichloromethane solution of the
dimeric precursor [{RuCl(m-Cl)(Z6-p-cymene)}2] with ca. 2.5
equivalents of 2. We note that neither the formation of the
cationic species [RuCl(k2-P,P-2)(Z6-p-cymene)][Cl] nor the
monodentate coordination of 2 through the Ph2P group were
observed in the crude reaction mixture by NMR spectroscopy.
Complex 8 has been characterized by elemental analyses and
multinuclear (1H, 31P{1H} and 13C{1H}) NMR spectroscopy
(details are given in the Experimental section). Key spectro-
scopic features are: (i) (31P{1H} NMR) the presence of two
doublet signals (JPP = 43.6 Hz) at dP ꢁ9.3 and 41.9 ppm,
corresponding to the diphenylphosphino Ph2P and phospho-
lane PhP moieties, respectively (the chemical shift of the latter
strongly supports its direct coordination to ruthenium), and
(ii) (1H and 13C{1H} NMR) the presence of characteristic
resonances for the methynic PCHP unit, whose proton ap-
pears as an unresolved multiplet at dH 3.82 ppm, and its
is attached to the metal in
a nearly linear fashion
(Ru–N(1)–C(1) = 171.5(14)1; N(1)–C(1)–C(2) = 178.0(19)1)
with bond lengths of Ru–N(1) = 2.043(14) A and N(1)–C(1)
= 1.16(2) A. These values compare well to those reported in
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
1298 | New J. Chem., 2006, 30, 1295–1306

View Article Online
Scheme 4 Synthesis, imination reactions and oxidation of the mononuclear complex 8.
carbon as a doublet of doublets (JCP = 33.7 and 23.5 Hz) at
dC 34.5 ppm.
subunits (RRu(1)SC(4)SP(1) and SRuRCRP configuration, respec-
tively)25 seems to indicate that a chiral self-recognition dimer-
ization process has also taken place.26
Reaction of complex 8 with a stoichiometric amount of
diphenylphosphoryl azide or 4-azido-2,3,5,6-tetrafluorobenzo-
nitrile in dichloromethane at room temperature leads to the
clean formation of complexes 9a–b, containing the novel
iminophosphorane–phosphine ligands G k1-P-coordinated to
ruthenium (Scheme 4). These compounds have been isolated
as air-stable orange solids in 70–74% yield after appropriate
work-up, being their analytical and spectroscopic data fully
consistent with the proposed structures (see the Experimental
section).28 In particular, the 31P{1H} NMR spectra show the
expected downfield shift of the Ph2P signal (dP = 17.5 (9a) and
21.5 (9b) ppm) with respect to that shown by the parent
complex 8 (dP = ꢁ9.3 ppm), confirming its transformation
into an iminophosphorane Ph2PQN unit (a slight downfield
shift (ca. Dd = 8 ppm) is also observed for the phospholane
Ru–PPh resonance in the course of these imination processes).
The reactivity of neutral complexes 9a–b towards AgSbF6
has also been explored. The results obtained, which are
comparable to those previously observed starting from the
regioisomeric species 5a–b (Scheme 3), are summarized in
Scheme 4. Thus, we have found that, while the treatment of
9a with 1 equivalent of AgSbF6 leads to the selective forma-
tion of the seven-membered chelate complex 10 (69% yield),
via preferred k2-P,O vs. k2-P,N coordination of the phos-
phorylated iminophosphorane–phosphine ligand, the dinuc-
lear species 11 is exclusively formed (79% yield) starting from
the fluorinated complex 9b. We also note that, as observed for
their regioisomers 6–7, compounds 10–11 were obtained as
non-separable mixtures of two diastereoisomers (the Ru atoms
are chiral centers in both complexes) in ca. 95 : 5 (10) and
60 : 40 (11) ratio. Characterization of 10–11 was achieved by
means of elemental analyses, IR and multinuclear NMR
spectroscopy (since their most characteristic spectroscopic
features are comparable to those observed for 6–7 they will
not be discussed further; details can be found in the Experi-
mental section). In addition, the structure of the major dia-
stereoisomer of the dinuclear derivative 11 has been
determined by X-ray diffraction. The molecular structure is
shown in Fig. 3; selected bond distances and angles are listed
in the caption, all of them falling within the expected range.
Once again, the molecule is a centrosymmetric dimer. The
inverted configurations found for the two individual metallic
The reluctance shown by the iminophosphorane–phosphine
ligands 3a–b and G to form five-membered chelate rings, via
k2-P,N coordination, contrasts with the behaviour shown by
the closely related diphosphine-monoxide H (Chart 4), from
which the cationic k2-P,O-chelate complex 13 could be easily
prepared (Scheme 4). Formation of 13 involves the initial
oxidation of the pendant Ph2P group of complex 8 and
subsequent chloride abstraction in the resulting oxidized spe-
cies 12. Oxidation of 8 was readily achieved under mild
Fig. 3 CAMERON-type view of the structure of complex 11 showing
the crystallographic labelling scheme. Unlabelled atoms are generateꢁd
by a crystallographic center of symmetry. Hydrogen atoms and SbF6
anions are omitted for clarity. Thermal ellipsoids are drawn at 30%
probability level. Selected bond lengths (A) and angles (1): Ru–C* =
1.71; Ru–Cl(1) = 2.396(2); Ru–P(1) = 2.342(2); Ru–N(2) = 2.022(7);
N(2)–C(17) = 1.157(11); C(17)–C(14) = 1.416(12); C(11)–N(1) =
1.366(11); P(2)–N(1) = 1.579(7); P(2)–C(4) = 1.805(8); P(1)–C(1) =
1.804(9); P(1)–C(4) = 1.876(9); C(1)–C(2) = 1.505(14); C(2)–C(3) =
1.551(15); C(3)–C(4) = 1.547(12); C*–Ru–Cl(1) = 127; C*–Ru–P(1)
= 128; C*–Ru–N(2) = 127; Cl(1)–Ru–N(2) = 87.0(2); Cl(1)–Ru–P(1)
= 85.77(8); P(1)–Ru–N(2) = 88.5(2); Ru–N(2)–C(17) = 175.5(7);
N(2)–C(17)–C(14) = 175.4(9); Ru–P(1)–C(1) = 112.2(3); Ru–P(1)–
C(4) = 116.3(2); Ru–P(1)–C(5) = 114.7(3); C(1)–P(1)–C(4) = 94.2(4);
C(1)–P(1)–C(5) = 106.0(4); C(4)–P(1)–C(5) = 111.2(4); P(1)–C(1)–C(2)
= 106.2(7); C(1)–C(2)–C(3) = 105.9(8); C(2)–C(3)–C(4) = 107.9(8);
C(3)–C(4)–P(1) = 105.5(6); C(3)–C(4)–P(2) = 112.6(6); C(4)–P(2)–N(1)
= 107.8(4); P(2)–N(1)–C(11) = 126.1(6). C* = centroid of the p-
cymene ring (C(34), C(35), C(36), C(37), C(38), C(39)). Symmetry code
related to moiety: 1 ꢁ x, 1 ꢁ y, 1 ꢁ z.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1295–1306 | 1299

View Article Online
Table 1 Diels–Alder reaction of acrolein with cyclopentadiene catalyzed by rutheniuma
Catalyst
Time/h
Yield (%)b
Endo : exob
ee (%)c
5a
5b
9a
9b
12
a
65
42
46
91
12
499
499
86
499
499
68 : 32
62 : 38
83 : 17
82 : 18
75 : 25
48
5
9
7
13
All reactions were conducted in CH2Cl2 at ꢁ20 1C using 1.5 mmol of acrolein, 9 mmol of CpH and the in situ Lewis acid generated from the
b
c
appropriate Ru–dichloride complex (5 mol%) and AgSbF6 (10 mol%). GC determined using cis-decaline as an internal standard. Enantio-
meric excess of the major endo cycloadduct (GC determined).
conditions (THF, r.t.) by using an excess (ca. 2 : 1) of tert-
butyl hydroperoxide.29 In this manner, complex 12 could be
isolated as an air-stable orange solid in excellent yield (94%),
being characterized by means of elemental analysis and NMR
spectroscopy. In particular, its 31P{1H} NMR spectrum clearly
confirms the presence of a Ph2PQO unit showing a character-
istic doublet signal (JPP = 19.6 Hz) at dP = 31.0 ppm (to be
compared with dP = ꢁ9.3 ppm (JPP = 43.6 Hz) for the non-
oxidized Ph2P unit in the parent complex 8). Remarkably, the
formation of the five-membered chelate ring of the cationic
complex 13 proceeds, as indicated by 31P{1H}, 1H and
13C{1H} NMR spectroscopy, in a diastereoselective manner,
a single set of signals being observed in the NMR spectra. We
also note that, as previously described in related (Z6-arene)–
ruthenium(II) complexes,30 the chelate coordination of the
diphosphine–monoxide ligand results in a downfield shift of
both PhP and Ph2PQO phosphorus resonances (ca. Dd = 8
and 3 ppm, respectively).
5a–b, 9a–b or 12 with 2 equivalents of AgSbF6.34 Selected
results are summarized in Table 1.
All the complexes studied have proven to be active catalysts
for this particular transformation, leading to the nearly quan-
titative formation of the bicyclic adduct in 12–90 h, with the
diphosphine–monoxide complex 12 showing the highest activ-
ity (499% yield after 12 h). Unfortunately, only a moderate
diastereoselectivity was observed, the endo cycloadduct being
predominant in all cases (endo : exo ratio from 62 : 38 to
83 : 17). The enantioselectivity of this process could also be
determined by using the corresponding enantiomerically pure
dichloride–Ru(II) precatalysts (obtained from (SPSC)-2). As
shown in Table 1, only an appreciable enantioselectivity (ee =
48%) was achieved starting from the N-phosphorylated pre-
cursor 5a. Unfortunately, when compared to other arene–
ruthenium(II) catalysts already reported in the litera-
ture,32,33 the catalytic performances of 5a–b, 9a–b and 12 are
in general lower both in term of activity and selectivity.
Catalytic Diels–Alder reactions
Conclusions
During recent years, organometallic ruthenium cations have
seen increased use as Lewis-acid catalysts for a variety of C–C
bond forming reactions.31 In particular, dicationic (Z6-arene)–
ruthenium(II) complexes containing optically active ligands
have recently found promising applications in asymmetric
Diels–Alder cycloaddition processes, offering an appealing
alternative to the classic Al-, B- or lanthanide-based Lewis-
acids, due to their increased stability and resistance to hydro-
lysis.32,33 With these precedents in mind, and taking into
account that enantiomerically pure iminophosphorane–
phosphine ligands can be readily accessible starting from the
enantiopure a-diphosphine (SPSC)-2 (Chart 1), we decided to
explore the catalytic activity of our ruthenium complexes in
this type of cycloaddition reaction. The Diels–Alder-type
coupling between acrolein and cyclopentadiene (5 mol% of
catalyst, CH2Cl2, ꢁ20 1C) was used as a model reaction. The
catalytically active species, i.e. the dications [Ru(L)(Z6-p-cym-
ene)]2+ (L = 3a–b or ligands of type G–H), were prepared in
situ by reacting the appropriate neutral dichloride precursor
In summary, novel iminophosphorane–phosphines have been
synthesized by selective Staudinger reactions on the a-dipho-
sphine 2-diphenylphosphino-1-phenyl-phospholane (2). Re-
markably, while selective imination of the more basic
dialkyl-P-phospholane phosphorus atom takes place starting
from the free diphosphine ligand, the diphenylphosphino
group can also be selectively transformed into an iminopho-
sphorane unit upon initial coordination of 2 to an (Z6-arene)–
ruthenium(II) fragment. To the best of our knowledge, no
examples of such a metal-template effect has been previously
reported in the chemistry of iminophosphoranes. The novel
regioisomeric iminophosphorane–phosphine ligands thus
formed have shown a rich coordination chemistry, allowing
the preparation of a variety of unusual mono- and dinuclear
arene–ruthenium complexes. In addition, all the complexes
synthesized were found to be active Lewis acid catalysts in
Diels–Alder reactions, albeit with moderate diastereo- and
enantioselectivities.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
1300 | New J. Chem., 2006, 30, 1295–1306

View Article Online
each, 4-C6F4CN) ppm. Anal. calc. for C29H22F4N2P2 (536.44):
C, 64.93; H, 4.13; N, 5.22; found: C, 65.10; H, 4.08; N, 5.15.
Experimental
General comments
Bis(iminophosphorane) derivative 4a. A solution of 2 (0.100
g, 0.287 mmol) in THF (5 mL) was treated, at room tempera-
ture, with diphenylphosphoryl azide (0.129 mL, 0.600 mmol)
for 6 d. The solvent was then removed under vacuum and the
resulting oily residue washed with pentane (2 ꢂ 3 mL) and
dried in vacuo to give 4a as a white solid. Yield: 0.198 g, 82%.
31P{1H} NMR (CDCl3): d ꢁ9.5 (d, JPP = 42.3 Hz, PQO),
ꢁ5.3 (d, JPP = 29.6 Hz, PQO), 12.1 (d, JPP = 42.3 Hz,
The manipulations were performed under an atmosphere of
dry nitrogen using vacuum-line and standard Schlenk techni-
ques. Solvents were dried by standard methods and distilled
under nitrogen before use. All reagents were obtained from
commercial suppliers with the exception of compounds
[{RuCl(m-Cl)(Z6-p-cymene)}2],18 2-diphenylphosphino-1-phe-
nyl-phospholane (2),13 and 4-azido-2,3,5,6-tetrafluorobenzo-
nitrile,35 which were prepared by following the methods
reported in the literature. Diphenylphosphoryl azide was
purchased from Aldrich and used without further purification.
Infrared spectra were recorded on a Perkin-Elmer 1720-XFT
spectrometer. The C, H and N analyses were carried out with a
Perkin-Elmer 2400 microanalyzer. GC measurements were
made on a Hewlett-Packard HP6890 equipment using a
Supelco Gama-Dext 225 (30 m, 250 mm) column. NMR
spectra were recorded on a Bruker DPX300 instrument at
300 MHz (1H), 121.5 MHz (31P), 282.4 MHz (19F), or 75.4
MHz (13C) using SiMe4, CFCl3 or 85% H3PO4 as standards.
Distortionless Enhancement by Polarisation Transfer (DEPT)
experiments have been carried out for all compounds reported
in this paper.
1
NQPPh2), 41.4 (d, JPP = 29.6 Hz, NQPPh) ppm. H NMR
(CDCl3): d 1.90–2.73 (m, 6H, CH2), 4.77 (m, 1H, PCHP),
7.03–7.84 (m, 35H, CHarom) ppm. 13C{1H} NMR (CDCl3): d
23.3 (dd, JCP = 12.1 and 4.5 Hz, CH2), 27.6 (dd, JCP = 9.1
and 1.5 Hz, CH2), 30.6 (d, JCP = 68.0 Hz, CH2P), 38.4 (ddd,
JCP = 68.8, 45.3 and 1.5 Hz, PCHP), 120.1–152.4 (m, Carom
and CHarom) ppm. Anal. calc. for C46H42O6P4N2 (842.73): C,
65.56; H, 5.02; N, 3.32; found: C, 65.40; H, 5.19; N, 3.39.
Bis(iminophosphorane) derivative 4b. A solution of 2 (0.100
g, 0.287 mmol) in THF (5 mL) was treated, at room tempera-
ture, with 4-azido-2,3,5,6-tetrafluorobenzonitrile (0.130 g,
0.600 mmol) for 24 h. The solvent was then removed under
vacuum and the resulting oily residue washed with pentane (2
ꢂ 3 mL) and dried in vacuo to give 4b as a yellow solid. Yield:
0.160 g, 77%. IR (KBr): 2229 cmꢁ1 (nCN). 31P{1H} NMR
Syntheses
1
Iminophosphorane–phosphine ligand 3a. A solution of 2
(0.198 g, 0.570 mmol) in THF (10 mL) was treated, at room
temperature, with diphenylphosphoryl azide (0.123 mL, 0.570
mmol) for 2 h. The solvent was then removed under vacuum
and the resulting oily residue washed with pentane (2 ꢂ 3 mL)
and dried in vacuo to give 3a as a white solid. Yield: 0.305 g,
90%. 31P{1H} NMR (C6D6): d ꢁ13.9 (d, JPP = 47.3 Hz,
PPh2), ꢁ5.1 (d, JPP = 31.9 Hz, PQO), 44.0 (dd, JPP = 47.3
and 31.9 Hz, NQPPh) ppm. 1H NMR (C6D6): d 1.52–2.35 (m,
(CDCl3): d 14.3 (br, NQPPh2), 43.6 (br, NQPPh) ppm. H
NMR (CDCl3): d 1.57–2.09 (m, 6H, CH2), 3.82 (m, 1H,
PCHP), 7.02–7.88 (m, 15H, CHarom) ppm. 13C{1H} NMR
(CD2Cl2): d 23.9 (d, JCP = 12.6 Hz, CH2), 28.4 (dd, JCP
=
11.4 and 2.4 Hz, CH2), 29.3 (dd, JCP = 53.5 and 3.0 Hz,
CH2P), 40.0 (dd, JCP = 74.3 and 23.8 Hz, PCHP), 107.2 and
109.5 (t, JCF = 3.8 Hz, CCRN), 128.1–149.1 (m, Carom and
CHarom) ppm; (CRN signals not observed). 19F{1H} NMR
(C6D6): d ꢁ153.80, ꢁ151.79, ꢁ139.59 and ꢁ139.01 (m, 2F
each, 4-C6F4CN) ppm. Anal. calc. for C36H22F8N4P2 (724.52):
C, 59.68; H, 3.06; N, 7.73; found: C, 59.56; H, 3.13; N, 7.59.
6H, CH2), 4.15 (m, 1H, PCHP), 7.09–8.30 (m, 25H, CHarom
)
ppm. 13C{1H} NMR (C6D6): d 28.8 (dd, JCP = 8.0 and 8.0 Hz,
CH2), 30.8 (d, JCP = 62.5 Hz, CH2P), 32.6 (dd, JCP = 19.9
and 8.3 Hz, CH2), 36.6 (dd, JCP = 54.7 and 24.3 Hz, PCHP),
121.1–153.3 (m, Carom and CHarom) ppm. Anal. calc. for
C34H32O3P3N (595.54): C, 68.57; H, 5.42; N, 2.35; found: C,
68.36; H, 5.30; N, 2.45.
Complex 5a. A solution of [{RuCl(m-Cl)(Z6-p-cymene)}2]
(0.145 g, 0.237 mmol) in dichloromethane (20 mL) was
treated, at room temperature, with the iminophosphora-
ne–phosphine ligand 3a (0.340 g, 0.570 mmol) for 1 h. The
solvent was then removed under vacuum and the resulting
orange solid residue washed with a 1 : 1 mixture of hexane :
diethyl ether (2 ꢂ 10 mL). Yield: 0.341 g, 80%. 31P{1H} NMR
(CDCl3): d ꢁ7.8 (d, JPP = 25.9 Hz, PQO), 21.7 (d, JPP = 38.8
Hz, Ru–PPh2), 41.6 (dd, JPP = 38.8 and 25.9 Hz, NQPPh)
Iminophosphorane–phosphine ligand 3b. A solution of 2
(0.100 g, 0.287 mmol) in THF (5 mL) was treated, at room
temperature, with 4-azido-2,3,5,6-tetrafluorobenzonitrile
(0.062 g, 0.287 mmol) for 30 min. The solvent was then
removed under vacuum and the resulting oily residue washed
with pentane (2 ꢂ 2 mL) and dried in vacuo to give 3b as a
yellow solid. Yield: 0.115 g, 75%. IR (KBr): 2226 cmꢁ1 (nCN).
31P{1H} NMR (C6D6): d ꢁ10.9 (d, JPP = 59.5 Hz, PPh2), 52.0
(d, JPP = 59.5 Hz, NQPPh) ppm. 1H NMR (C6D6): d
1.78–2.63 (m, 6H, CH2), 3.42 (m, 1H, PCHP), 7.13–7.75 (m,
1
ppm. H NMR (CDCl3): d 0.69, 1.93 and 3.05 (m, 1H each,
CH2), 0.89 and 1.08 (d, 3H each, JHH = 6.9 Hz, CH(CH3)2),
1.68 (br, 4H, CH3 and CH2), 2.30 (m, 2H, CH2), 2.46 (m, 1H,
CH(CH3)2), 4.43 (m, 1H, PCHP), 4.64 and 4.92 (d, 1H each,
JHH = 6.0 Hz, CH of cymene), 5.13 and 5.18 (d, 1H each, JHH
= 6.3 Hz, CH of cymene), 6.88–7.98 (m, 25H, CHarom) ppm.
13C{1H} NMR (CD2Cl2): d 17.1 (s, CH3), 21.5 and 22.1 (s,
CH(CH3)2), 22.5 (d, JCP = 9.7 Hz, CH2), 27.2 (d, JCP = 62.8
Hz, CH2P), 30.0 (s, CH(CH3)2), 31.5 (d, JCP = 13.2 Hz, CH2),
38.9 (ddd, JCP = 63.7, 13.3 and 7.1 Hz, PCHP), 84.4 and 92.2
(d, JCP = 5.3 Hz, CH of cymene), 85.6 (d, JCP = 7.1 Hz, CH
of cymene), 89.1 (d, JCP = 2.6 Hz, CH of cymene), 94.8 and
15H, CHarom) ppm. 13C{1H} NMR (C6D6): d 24.7 (dd, JCP
=
7.8 and 7.8 Hz, CH2), 29.6 (dd, JCP = 54.8 and 1.7 Hz, CH2P),
31.2 (dd, JCP = 18.1 and 9.9 Hz, CH2), 39.0 (dd, JCP = 75.7
and 24.4 Hz, PCHP), 71.2 (t, JCF = 15.0 Hz, CRN), 109.9 (t,
JCF = 3.5 Hz, CCRN), 125.8–149.6 (m, Carom and CHarom
)
ppm. 19F{1H} NMR (C6D6): d ꢁ155.27 and ꢁ139.45 (m, 2F
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1295–1306 | 1301

View Article Online
109.5 (s, C of cymene), 120.7–152.2 (m, Carom and CHarom
)
cymene), 4.44 (m, 1H, PCHP), 5.44 and 5.51 (d, 1H each, JHH
= 6.0 Hz, CH of cymene), 6.89–7.69 (m, 25H, CHarom) ppm.
13C{1H} NMR (CDCl3): d 15.9 (s, CH3), 19.7 (d, JCP = 6.0
Hz, CH2), 21.2 and 21.5 (s, CH(CH3)2), 26.3 (d, JCP = 13.0
Hz, CH2), 29.7 (s, CH(CH3)2), 32.6 (d, JCP = 75.6 Hz, CH2P),
35.9 (dd, JCP = 47.5 and 15.1 Hz, PCHP), 84.0 (d, JCP = 5.5
Hz, CH of cymene), 86.0 (d, JCP = 4.4 Hz, CH of cymene),
87.4 (d, JCP = 2.7 Hz, CH of cymene), 94.1 and 106.7 (s, C of
cymene), 95.6 (d, JCP = 5.0 Hz, CH of cymene), 119.4–151.0
(m, Carom and CHarom) ppm.
ppm. Anal. calc. for RuC44H46O3P3Cl2N (901.74): C, 58.61;
H, 5.14; N, 1.55; found: C, 58.47; H, 5.26; N, 1.40.
Complex 5b. Complex 5b, isolated as an orange solid, was
prepared as described for 5a starting from [{RuCl(m-Cl)(Z6-p-
cymene)}2] (0.145 g, 0.237 mmol) and 3b (0.306 g, 0.570
mmol). Yield: 0.327 g, 82%. IR (KBr): 2227 cmꢁ1 (nCN).
31P{1H} NMR (C6D6): d 23.4 (d, JPP = 37.8 Hz, Ru–PPh2),
1
44.1 (d, JPP = 37.8 Hz, NQPPh) ppm. H NMR (C6D6): d
0.59–1.65 (m, 5H, CH2), 0.80 and 0.97 (d, 3H each, JHH = 6.8
Hz, CH(CH3)2), 1.36 (s, 3H, CH3), 2.47 (m, 1H, CH(CH3)2),
3.30 (m, 1H, CH2), 4.28 and 4.98 (d, 1H each, JHH = 6.0 Hz,
CH of cymene), 4.49 and 4.56 (d, 1H each, JHH = 5.7 Hz, CH
Complex 7. The orange complex 7, isolated as a unseparable
mixture of two diastereoisomers in ca. 75 : 25 ratio, was
prepared as described for 6 starting from 5b (0.200 g, 0.237
mmol) and AgSbF6 (0.086 g, 0.250 mmol). Yield: 0.222 g,
90%. Anal. calc. for Ru2C78H72F20N4P4Cl2Sb2 (2085.86): C,
44.91; H, 3.48; N, 2.69; found: C, 44.87; H, 3.65; N, 2.48.
Spectroscopic data for the major diastereoisomer are as follows:
IR (KBr): 2234 cmꢁ1 (nCN). 31P{1H} NMR (CD2Cl2): d 30.3
(d, JPP = 34.3 Hz, Ru–PPh2), 44.6 (d, JPP = 34.3 Hz,
NQPPh) ppm. 1H NMR (CD2Cl2): d 0.95 and 1.13 (d, 6H
each, JHH = 6.8 Hz, CH(CH3)2), 1.41–1.75 (m, 4H, CH2), 1.82
(s, 6H, CH3), 1.86–2.52 (m, 8H, CH2 and CH(CH3)2), 2.79 (m,
2H, CH2), 3.40 (m, 2H, PCHP), 5.00, 5.16, 5.42 and 5.75 (d,
2H each, JHH = 6.3 Hz, CH of cymene), 6.39–7.99 (m, 30H,
CHarom) ppm. 19F{1H} NMR (CD2Cl2): d ꢁ154.41 and
ꢁ135.59 (m, 4F each, 4-C6F4CN) ppm. Spectroscopic data
for the minor diastereoisomer are as follows: IR (KBr): 2234
cmꢁ1 (nCN). 31P{1H} NMR (CD2Cl2): d 30.9 (d, JPP = 31.0
of cymene), 4.97 (m, 1H, PCHP), 6.62–8.06 (m, 15H, CHarom
)
ppm. 13C{1H} NMR (C6D6): d 17.1 (s, CH3), 20.0 and 23.1 (s,
CH(CH3)2), 22.0 (d, JCP = 10.8 Hz, CH2), 27.6 (d, JCP = 52.9
Hz, CH2P), 30.1 (s, CH(CH3)2), 30.4 (d, JCP = 7.5 Hz, CH2),
37.5 (dd, JCP = 59.3 and 13.1 Hz, PCHP), 78.5 (t, JCF = 13.0
Hz, CRN), 85.3, 85.5, 88.9 and 91.7 (s, CH of cymene), 94.8
and 109.2 (s, C of cymene), 109.7 (br, CCRN), 121.9–153.5
(m, Carom and CHarom) ppm. 19F{1H} NMR (C6D6): d
ꢁ154.78 and ꢁ139.60 (m, 2F each, 4-C6F4CN) ppm. Anal.
calc. for RuC39H36F4Cl2N2P2 (842.63): C, 55.59; H, 4.31; N,
3.32; found: C, 55.79; H, 4.53; N, 3.13.
Complex 6. A solution of complex 5a (0.154 g, 0.171 mmol)
in dichloromethane (20 mL) was treated, at room temperature
and in the absence of light, with AgSbF6 (0.059 g, 0.171 mmol)
for 2 h. After the AgCl thus formed was filtered off (Kiesel-
guhr), the solution was evaporated to dryness, and the result-
ing solid orange residue washed with diethyl ether (3 ꢂ 10 mL)
and dried in vacuo. Complex 6 was isolated as a non-separable
mixture of two diastereoisomers in ca. 60 : 40 ratio. Yield:
0.139 g, 74%. Anal. calc. for RuC44H46F6O3P3ClNSb
(1102.04): C, 47.96; H, 4.21; N, 1.27; found: C, 47.80; H,
4.33; N, 1.33. Spectroscopic data for the major diastereoisomer
are as follows: 31P{1H} NMR (CDCl3): d 8.7 (dd, JPP = 27.0
and 2.8 Hz, PQO–Ru), 25.3 (dd, JPP = 6.9 and 2.8 Hz,
Ru–PPh2), 44.3 (dd, JPP = 27.0 and 6.9 Hz, NQPPh) ppm. 1H
NMR (CDCl3): d 0.90 and 1.03 (d, 3H each, JHH = 6.8 Hz,
CH(CH3)2), 1.78 (s, 3H, CH3), 1.84–2.80 (m, 7H, CH2 and
CH(CH3)2), 4.61 (m, 1H, PCHP), 4.72 and 4.83 (d, 1H each,
1
Hz, Ru–PPh2), 40.6} (d, JPP = 31.0 Hz, NQPPh) ppm. H
NMR (CD2Cl2): d 0.98 and 1.19 (d, 6H each, JHH = 6.5 Hz,
CH(CH3)2), 1.41–1.75 (m, 4H, CH2), 1.54 (s, 6H, CH3),
1.86–2.52 (m, 8H, CH2 and CH(CH3)2), 2.79 (m, 2H, CH2),
3.40 (m, 2H, PCHP), 5.00, 5.16, 5.49 and 5.80 (d, 2H each, JHH
= 6.3 Hz, CH of cymene), 6.39–7.99 (m, 30H, CHarom) ppm.
19F{1H} NMR (CD2Cl2): d ꢁ152.85 and ꢁ136.91 (m, 4F each,
4-C6F4CN) ppm. This compound was not soluble enough to
be characterized by 13C{1H} NMR spectroscopy.
Complex 8. A solution of [{RuCl(m-Cl)(Z6-p-cymene)}2]
(0.234 g, 0.382 mmol) in dichloromethane (25 mL) was
treated, at room temperature, with 2-diphenylphosphino-1-
phenyl-phospholane (2) (0.320 g, 0.917 mmol) for 1 h. The
solvent was then removed in vacuo and the resulting solid
orange residue washed with a 1 : 1 mixture of hexane : diethyl
ether (3 ꢂ 10 mL). Yield: 0.460 g, 92%. 31P{1H} NMR
JHH = 6.0 Hz, CH of cymene), 5.35 and 5.62 (d, 1H each, JHH
= 5.2 Hz, CH of cymene), 6.89–7.69 (m, 25H, CHarom) ppm.
13C{1H} NMR (CDCl3): d 17.3 (s, CH3), 20.9 and 21.4 (s,
CH(CH3)2), 22.3 (d, JCP = 8.8 Hz, CH2), 25.1 (dd, JCP = 18.0
and 6.0 Hz, CH2), 29.6 (s, CH(CH3)2), 32.6 (d, JCP = 75.6 Hz,
CH2P), 39.7 (dd, JCP = 43.9 and 8.8 Hz, PCHP), 83.3 and 87.9
(s, CH of cymene), 85.5 (d, JCP = 7.7 Hz, CH of cymene), 89.8
(d, JCP = 2.7 Hz, CH of cymene), 92.9 and 106.4 (s, C of
cymene), 119.4–151.0 (m, Carom and CHarom) ppm. Spectro-
scopic data for the minor diastereoisomer are as follows:
31P{1H} NMR (CDCl3): d 6.2 (dd, JPP = 22.8 and 5.3 Hz,
PQO–Ru), 25.6 (dd, JPP = 6.4 and 5.3 Hz, Ru–PPh2), 44.0
(dd, JPP = 22.8 and 6.4 Hz, NQPPh) ppm. 1H NMR
(CDCl3): d 0.82 and 1.10 (d, 3H each, JHH = 6.6 Hz,
CH(CH3)2), 1.29 (s, 3H, CH3), 1.84–2.80 (m, 7H, CH2 and
CH(CH3)2), 4.19 and 4.86 (d, 1H each, JHH = 5.8 Hz, CH of
(CDCl3): d ꢁ9.3 (d, JPP = 43.6 Hz, PPh2), 41.9 (d, JPP
=
43.6 Hz, Ru–PPh) ppm. 1H NMR (CDCl3): d 1.19 (d, 3H, JHH
= 6.9 Hz, CH(CH3)2), 1.21 (d, 3H, JHH = 7.1 Hz,
CH(CH3)2), 1.69 and 2.60 (m, 2H each, CH2), 1.90 (s, 3H,
CH3), 1.98 and 2.18 (m, 1H each, CH2), 2.78 (m, 1H,
CH(CH3)2), 3.82 (m, 1H, PCHP), 5.01 and 5.38 (d, 1H each,
JHH = 5.7 Hz, CH of cymene), 5.17 and 5.21 (d, 1H each, JHH
= 6.1 Hz, CH of cymene), 6.86–7.98 (m, 15H, CHarom) ppm.
13C{1H} NMR (CDCl3): d 18.0 (s, CH3), 21.7 and 22.4 (s,
CH(CH3)2), 26.6 and 32.8 (s, CH2), 27.7 (d, JCP = 29.2 Hz,
CH2P), 30.4 (s, CH(CH3)2), 34.5 (dd, JCP = 33.7 and 23.5 Hz,
PCHP), 85.2 (d, JCP = 5.7 Hz, CH of cymene), 86.1 (br, 2C,
CH of cymene), 88.4 (d, JCP = 5.1 Hz, CH of cymene), 96.6 (s,
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
1302 | New J. Chem., 2006, 30, 1295–1306

View Article Online
C of cymene), 109.1 (d, JCP = 2.5 Hz, C of cymene),
127.6–137.3 (m, Carom and CHarom) ppm. Anal. calc. for
RuC32H36Cl2P2 (654.55): C, 58.72; H, 5.54; found: C, 58.62;
H, 5.37.
Yield: 0.130 g, 69%. Anal. calc. for RuC44H46F6O3P3ClNSb
(1102.04): C, 47.96; H, 4.21; N, 1.27; found: C, 47.85; H, 3.99;
N, 1.08. Spectroscopic data for the major diastereoisomer are as
follows: 31P{1H} NMR (CDCl3): d 0.9 (d, JPP = 34.9 Hz,
PQO–Ru), 17.0 (d, JPP = 34.9 Hz, Ph2PQN), 49.2 (s,
Ru–PPh) ppm. 1H NMR (CDCl3): d 0.92–2.72 (m, 6H,
CH2), 1.21 and 1.28 (d, 3H each, JHH = 7.0 Hz, CH(CH3)2),
1.82 (s, 3H, CH3), 2.95 (m, 1H, CH(CH3)2), 4.58 (m, 1H,
PCHP), 5.18 and 5.87 (d, 1H each, JHH = 5.7 Hz, CH of
cymene), 5.39 and 5.67 (d, 1H each, JHH = 6.3 Hz, CH of
cymene), 6.84–7.74 (m, 25H, CHarom) ppm. 13C{1H} NMR
(CDCl3): d 18.8 (s, CH3), 21.3 and 23.0 (s, CH(CH3)2), 28.4
(dd, JCP = 15.6 and 5.1 Hz, CH2), 29.6 (dd, JCP = 31.2 and
15.4 Hz, CH2P), 30.6 (s, CH2), 31.4 (s, CH(CH3)2), 39.9 (dd,
Complex 9a. A solution of 8 (0.200 g, 0.305 mmol) in
dichloromethane (20 mL) was treated, at room temperature,
with diphenylphosphoryl azide (0.066 mL, 0.305 mmol) for 7
days. The solvent was then removed under vacuum and the
resulting orange solid residue washed with a 1 : 1 mixture of
hexane : diethyl ether (3 ꢂ 10 mL) and dried in vacuo. Yield:
0.193 g, 70%. 31P{1H} NMR (CDCl3): d ꢁ11.0 (d, JPP = 40.2
Hz, PQO), 17.5 (dd, JPP = 40.2 and 27.2 Hz, Ph2PQN), 48.6
1
(d, JPP = 27.2 Hz, Ru–PPh) ppm. H NMR (CDCl3): d 1.24
(d, 6H, JHH = 6.8 Hz, CH(CH3)2), 1.79 (s, 3H, CH3),
2.17–3.73 (m, 7H, CH2 and CH(CH3)2), 4.09 (m, 1H, PCHP),
4.83 and 5.37 (d, 1H each, JHH = 4.8 Hz, CH of cymene), 4.96
and 5.26 (d, 1H each, JHH = 5.2 Hz, CH of cymene),
6.34–7.69 (m, 25H, CHarom) ppm. 13C{1H} NMR (CDCl3): d
15.2 (s, CH3), 21.9 and 22.3 (s, CH(CH3)2), 26.3 and 32.5 (s,
CH2), 30.6 (s, CH(CH3)2), 30.9 (d, JCP = 31.7 Hz, CH2P), 33.5
(ddd, JCP = 71.0, 15.0 and 3.6 Hz, PCHP), 85.7 (s, CH of
cymene), 86.4 (d, JCP = 8.2 Hz, CH of cymene), 87.2 and 88.0
(d, JCP = 7.2 Hz, CH of cymene), 97.0 (s, C of cymene), 110.1
(d, JCP = 7.2 Hz, C of cymene), 120.1–152.4 (m, Carom and
CHarom) ppm. Anal. calc. for RuC44H46O3P3Cl2N (901.74): C,
58.61; H, 5.14; N, 1.55; found: C, 58.40; H, 5.32; N, 1.48.
J
CP = 61.0 and 14.6 Hz, PCHP), 81.7 (s, CH of cymene), 87.4
(d, JCP = 1.9 Hz, CH of cymene), 87.5 (d, JCP = 3.2 Hz, CH
of cymene), 89.2 (d, JCP = 6.0 Hz, CH of cymene), 97.4 (s, C
of cymene), 112.5 (d, JCP = 5.7 Hz, C of cymene), 120.5–152.0
(m, Carom and CHarom) ppm. Spectroscopic data for the minor
diastereoisomer are as follows: 31P{1H} NMR (CDCl3): d ꢁ0.6
(d, JPP = 33.2 Hz, PQO–Ru), 15.9 (d, JPP = 33.2 Hz,
Ph2PQN), 49.2 (s, Ru–PPh) ppm. 1H NMR (CDCl3): d
0.92–2.72 (m, 6H, CH2), 1.09 and 1.33 (d, 3H each, JHH
=
6.9 Hz, CH(CH3)2), 1.99 (s, 3H, CH3), 2.95 (m, 1H,
CH(CH3)2), 4.58 (m, 1H, PCHP), 5.28 (br, 2H, CH of
cymene), 5.46 and 5.73 (d, 1H each, JHH = 6.0 Hz, CH of
cymene), 6.84–7.74 (m, 25H, CHarom) ppm.
Complex 9b. Complex 9b, isolated as an orange solid, was
prepared as described for 9a starting from 8 (0.100 g, 0.153
mmol) and 4-azido-2,3,5,6-tetrafluorobenzonitrile (0.033 g,
0.153 mmol). Reaction time: 8 h. Yield: 0.095 g, 74%. IR
(KBr): 2226 cmꢁ1 (nCN). 31P{1H} NMR (CDCl3): d 21.5 (d,
JPP = 28.5 Hz, Ph2PQN), 49.6 (d, JPP = 28.5 Hz, Ru–PPh)
ppm. 1H NMR (CDCl3): d 1.27 (d, 6H, JHH = 4.3 Hz,
CH(CH3)2), 1.84 (s, 3H, CH3), 2.40 (m, 3H, CH2), 2.71 (m,
2H, CH2), 2.92 (m, 1H, CH(CH3)2), 3.21 (m, 1H, CH2), 3.83
(m, 1H, PCHP), 4.82 and 4.90 (d, 1H each, JHH = 4.8 Hz, CH
of cymene), 5.19 and 5.41 (d, 1H each, JHH = 5.1 Hz, CH of
cymene), 7.02–7.61 (m, 15H, CHarom) ppm. 13C{1H} NMR
(CDCl3): d 18.2 (s, CH3), 21.9 and 22.3 (s, CH(CH3)2), 26.9
and 37.8 (s, CH2), 30.6 (s, CH(CH3)2), 31.3 (d, JCP = 30.6 Hz,
CH2P), 36.1 (dd, JCP = 81.1 and 12.6 Hz, PCHP), 79.3 (t, JCF
= 11.0 Hz, CRN), 85.7, 86.8 and 87.0 (s, CH of cymene),
87.7 (d, JCP = 3.5 Hz, CH of cymene), 97.1 (s, C of cymene),
107.1 (t, JCF = 4.0 Hz, CCRN), 110.5 (d, JCP = 5.3 Hz, C of
cymene), 128.6–152.8 (m, Carom and CHarom) ppm. 19F{1H}
NMR (CDCl3): d ꢁ151.65, ꢁ149.11, ꢁ138.79 and ꢁ132.50 (m,
1F each, 4-C6F4CN) ppm. Anal. calc. for RuC39H36
F4Cl2N2P2 (842.63): C, 55.59; H, 4.31; N, 3.32; found: C,
55.36; H, 4.23; N, 3.42.
Complex 11. The orange complex 11, isolated as a non-
separable mixture of two diastereoisomers in ca. 60 : 40 ratio,
was prepared as described for 10 starting from 9b (0.185 g,
0.219 mmol) and AgSbF6 (0.075 g, 0.219 mmol). Yield: 0.180
g, 79%. Anal. calc. for Ru2C78H72F20N4P4Cl2Sb2 (2085.86):
C, 44.91; H, 3.48; N, 2.69; found: C, 45.26; H, 3.56; N, 2.57.
Spectroscopic data for the major diastereoisomer are as follows:
IR (KBr): 2259 cmꢁ1 (nCN). 31P{1H} NMR (acetone-d6): d 25.6
(d, JPP = 20.2 Hz, Ph2PQN), 52.2 (d, JPP = 20.2 Hz,
1
Ru–PPh) ppm. H NMR (acetone-d6): d 0.85–3.45 (m, 14H,
CH2 and CH(CH3)2), 1.12–1.35 (m, 12H, CH(CH3)2), 2.03 (s,
6H, CH3), 4.55 (m, 2H, PCHP), 5.60 (br, 2H, CH of cymene),
5.92–6.12 (m, 6H, CH of cymene), 7.13–7.80 (m, 30H, CHarom
)
ppm. 13C{1H} NMR (acetone-d6): d 23.4 (s, CH3), 27.4 and
27.6 (s, CH(CH3)2), 34.4 and 40.0 (s, CH2), 37.0 (s,
CH(CH3)2), 38.6 (d, JCP = 33.6 Hz, CH2P), 41.8 (dd, JCP
=
53.4 and 13.8 Hz, PCHP), 94.1, 97.0, 97.9 and 98.6 (s, CH of
cymene), 107.9 and 119.1 (s, C of cymene), 124.1 (br,
CCRN), 134.5–156.1 (m, Carom and CHarom) ppm; CRN
signal not observed. 19F{1H} NMR (acetone-d6): d ꢁ148.34
and ꢁ137.04 (m, 4F each, 4-C6F4CN) ppm. Spectroscopic data
for the minor diastereoisomer are as follows: IR (KBr): 2259
cmꢁ1 (nCN). 31P{1H} NMR (acetone-d6): d 25.2 (d, JPP = 20.2
Hz, Ph2PQN), 57.9 (d, JPP = 20.2 Hz, Ru–PPh) ppm. 1H
NMR (acetone-d6): d 0.85–3.45 (m, 14H, CH2 and CH(CH3)2),
1.12–1.35 (m, 12H, CH(CH3)2), 1.86 (s, 6H, CH3), 4.63 (m,
2H, PCHP), 5.60 (br, 2H, CH of cymene), 5.92–6.12 (m, 6H,
CH of cymene), 7.13–7.80 (m, 30H, CHarom) ppm. 13C{1H}
NMR (acetone-d6): d 23.2 (s, CH3), 27.2 and 27.6 (s,
CH(CH3)2), 34.1 and 39.9 (s, CH2), 36.9 (s, CH(CH3)2), 38.6
(d, JCP = 33.6 Hz, CH2P), 42.9 (dd, JCP = 53.4 and 13.8 Hz,
Complex 10. A solution of complex 9a (0.154 g, 0.171 mmol)
in dichloromethane (10 mL) was treated, at room temperature
and in the absence of light, with AgSbF6 (0.059 g, 0.171 mmol)
for 2 h. After the AgCl formed was filtered off (Kieselguhr),
the solution was evaporated to dryness, and the resulting
orange solid residue washed with diethyl ether (3 ꢂ 10 mL)
and dried in vacuo. Complex 10 was isolated as a non-sepa-
rable mixture of two diastereoisomers in ca. 95 : 5 ratio.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1295–1306 | 1303

View Article Online
Table 2 Selected crystallographic data for complexes 5a, 7 and 11
Complex 5a
Complex 7
Complex 11
Empirical formula
Formula weight
Temperature/K
Wavelength/A
Crystal system
Space group
a/A
b/A
c/A
a/1
RuC44H46O3P3Cl2N ꢃ CHCl3
Ru2C78H72F20N4P4Cl2Sb2
2085.86
180(2)
0.71073
Triclinic
P-1
9.2949(18)
12.576(3)
18.412(3)
101.298(17)
90.983(15)
95.652(17)
2098.8(7)
Ru2C78H72F20N4P4Cl2Sb2 ꢃ 2Et2O
1021.07
180(2)
2234.10
180(2)
0.71073
Monoclinic
P21/c
22.247(4)
10.040(2)
20.632(4)
90
95.89(3)
90
4584.0(16)
4
0.779
0.71073
Monoclinic
P21/c
15.4570(10)
14.6930(8)
20.1840(11)
90
99.750(5)
90
4517.8(5)
2
1.139
b/1
g/1
Volume/A3
Z
1
1.218
m/mmꢁ1
Reflns/unique
Refinement
Weighting scheme
Final R1
34425/9554
on F
Chebychev polynomial
0.0417 [I 4 2.5s(I)]
0.0493 [I 4 2.5s(I)]
12150/6010
on F
Chebychev polynomial
0.0831 [I 4 2s(I)]
0.0848 [I 4 2s(I)]
39404/12075
on F
Chebychev polynomial
0.0637 [I 4 2s(I)]
0.0675 [I 4 2s(I)]
Final wR2
PCHP), 93.6, 96.8 and 97.0 (s, CH of cymene), 97.6 (d,
JCP = 6.0 Hz, CH of cymene), 108.5 and 120.1 (s, C of
cymene), 124.1 (br, CCRN), 134.5–156.1 (m, Carom and
CHarom) ppm; CRN signal not observed. 19F{1H} NMR
(acetone-d6): d ꢁ147.04 and ꢁ135.70 (m, 4F each, 4-
C6F4CN) ppm.
5.78 and 6.06 (d, 1H each, JHH = 6.5 Hz, CH of cymene), 5.94
and 6.09 (d, 1H each, JHH = 6.0 Hz, CH of cymene),
7.23–8.04 (m, 15H, CHarom) ppm. 13C{1H} NMR (CDCl3): d
18.4 (s, CH3), 22.1 and 22.4 (s, CH(CH3)2), 27.3 (dd, JCP
=
14.6 and 5.1 Hz, CH2), 29.2 (d, JCP = 31.2 and 5.7 Hz, CH2P),
29.4 (s, CH2), 31.6 (s, CH(CH3)2), 39.9 (dd, JCP = 67.4 and
14.0 Hz, PCHP), 85.6 (d, JCP = 5.1 Hz, CH of cymene), 87.3
and 88.2 (d, JCP = 3.8 Hz, CH of cymene), 88.6 (d, JCP = 3.2
Hz, CH of cymene), 97.4 and 109.1 (s, C of cymene),
124.6–134.1 (m, Carom and CHarom) ppm. Anal. calc. for
RuC32H36F6P2ClOSb (870.85): C, 44.14; H, 4.17; found: C,
43.83; H, 4.34.
Complex 12. A solution of 8 (0.160 g, 0.244 mmol) in THF
t
(20 mL) was treated, at room temperature, with BuOOH
(0.100 mL, 0.500 mmol) for 3 h. The solvent was then removed
under vacuum and the resulting orange solid residue washed
with a 1 : 1 mixture of hexane : diethyl ether (3 ꢂ 10 mL) and
dried in vacuo. Yield: 0.154 g, 94%. 31P{1H} NMR (CDCl3): d
31.0 (d, JPP = 19.6 Hz, Ph2PQO), 46.2 (d, JPP = 19.6 Hz,
General procedure for the catalytic Diels–Alder reaction
1
Ru–PPh) ppm. H NMR (CDCl3): d 1.15 (d, 6H, JHH = 6.8
A Schlenk tube was charged, under N2 atmosphere, with the
corresponding neutral dichloride–ruthenium(II) pre-catalyst
(0.075 mmol) and AgSbF6 (0.051 g, 0.15 mmol). CH2Cl2 (5
mL) was added and the mixture stirred at room temperature
for 30 min, followed by filtration (over Kieselguhr) to remove
the precipitated AgCl. The filtrate was evaporated to dryness,
dissolved in 2 mL of CH2Cl2 and transferred, under N2
atmosphere, into a jacketed Schlenk tube refrigerated by a
Hz, CH(CH3)2), 1.80 (s, 3H, CH3), 1.99–2.86 (m, 7H, CH2 and
CH(CH3)2), 3.86 (m, 1H, PCHP), 5.03 and 5.40 (d, 1H each,
JHH = 5.7 Hz, CH of cymene), 5.15 (br, 2H, CH of cymene),
6.82–7.95 (m, 15H, CHarom) ppm. 13C{1H} NMR (CDCl3): d
18.1 (s, CH3), 21.8 and 22.3 (s, CH(CH3)2), 27.0 and 32.9 (s,
CH2), 30.1 (s, CH(CH3)2), 30.5 (d, JCP = 31.4 Hz, CH2P), 36.6
(dd, JCP = 62.5 and 15.6 Hz, PCHP), 86.0 (s, 2C, CH of
cymene), 86.9 (d, JCP = 4.8 Hz, CH of cymene), 87.3 (d, JCP
= 3.6 Hz, CH of cymene), 96.8 (s, C of cymene), 110.2 (d, JCP
i
closed PrOH circuit kept at ꢁ20 1C with a cryostat. Freshly
distilled acrolein (0.1 mL, 1.5 mmol), 2,6-lutidine (4 mL, 0.0375
mmol) and cis-decaline (0.231 mL, 1.5 mmol) were added. The
resulting yellow solution was equilibrated at ꢁ20 1C for 30
min before addition of freshly distilled cyclopentadiene (0.6
mL, 9 mmol). The course of the reaction, i.e. conversion, endo :
exo ratio and ee excess, was monitored by GC [Supelco Gama-
Dext 225 (30 m, 250 mm) column; helium 4 mL minꢁ1, 60 1C,
10 1C minꢁ1 to 200 1C: 5.53 min (cis-decaline), 5.88 and 6.00
min (exo cycloadducts), 6.60 and 6.66 min (endo cycloadducts)].
= 4.4 Hz, C of cymene), 127.2–130.3 (m, Carom and CHarom
)
ppm. Anal. calc. for RuC32H36Cl2P2O (670.55): C, 57.32; H,
5.41; found: C, 57.14; H, 5.38.
Complex 13. A solution of complex 12 (0.097 g, 0.145 mmol)
in dichloromethane (10 mL) was treated, at room temperature
and in the absence of light, with AgSbF6 (0.050 g, 0.145 mmol)
for 2 h. After the AgCl formed was filtered off (Kieselguhr),
the solution was evaporated to dryness, and the resulting
orange solid residue washed with diethyl ether (3 ꢂ 10 mL)
and dried in vacuo. Yield: 0.076 g, 60%. 31P{1H} NMR
(CDCl3): d 39.5 (d, JPP = 3.5 Hz, Ph2PQO–Ru), 49.1 (d,
X-Ray crystal structure determination of complexes 5a, 7 and 11
Single crystals suitable for X-ray diffraction analysis were
obtained, in all cases, by slow diffusion of diethyl ether into
a saturated solution of the complex in dichloromethane. The
most relevant crystallographic data are given in Table 2. Data
J
PP = 3.5 Hz, Ru–PPh) ppm. 1H NMR (CDCl3): d 1.42–3.44
(m, 7H, CH2 and CH(CH3)2), 1.47 and 1.49 (d, 3H each, JHH
= 6.8 Hz, CH(CH3)2), 2.13 (s, 3H, CH3), 4.41 (m, 1H, PCHP),
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
1304 | New J. Chem., 2006, 30, 1295–1306

View Article Online
were collected at low temperature on an Xcalibur Oxford
Diffraction diffractometer using a graphite-monochromated
Mo-Ka radiation and equipped with an Oxford Cryosystems
Cryostream Cooler Device. The structures have been solved by
Direct Methods using SIR92,36 and refined by means of least-
squares procedures on F using the programs of the PC version
of CRYSTALS.37 The Atomic Scattering Factors were taken
from International Tables for X-Ray Crystallography.38 Com-
plex 5a contains two disordered phenyl rings refined isotropi-
cally. All other non-H atoms were refined anisotropically. The
poor quality of the data for complex 7 did not allow the
refinement with anisotropic thermal parameters, except for
ruthenium, phosphorus, antimony and chlorine atoms. The
structure of compound 11 was refined with anisotropic thermal
parameters for all non-hydrogen atoms and ether molecules.
CCDC reference numbers 612113–612115.
Sun, J. Organomet. Chem., 2005, 690, 3946; (j) N. D. Jones and R.
G. Cavell, J. Organomet. Chem., 2005, 690, 5485, and references
cited therein; (k) V. Cadierno, M. Zablocka, B. Donnadieu, A.
Igau, J.-P. Majoral and A. Skowronska, Chem.–Eur. J., 2000, 6,
346; (l) J. P. Majoral and M. Zablocka, New J. Chem., 2005, 29, 32.
5 For overviews on the coordination chemistry of iminophospho-
rane–phosphine ligands see: (a) K. V. Katti and R. G. Cavell,
Comments Inorg. Chem., 1990, 10, 53; (b) R. G. Cavell, Curr. Sci.,
2000, 78, 440.
6 (a) D. J. Law and R. G. Cavell, J. Mol. Catal., 1994, 91, 175; (b) R.
G. Cavell, D. J. Law and R. W. Reed, US. Pat. Appl., US 887014,
1994; (c) T. T. Co, S. C. Shim, C. S. Cho, T.-J. Kim, S. O. Kang,
W.-S. Han, J. Ko and C.-K. Kim, Organometallics, 2005, 24, 4824.
7 (a) R. G. Cavell, B. Creed, L. Gelmini, D. J. Law, R. McDonald,
A. R. Sanger and A. Somogyvary, Inorg. Chem., 1998, 37, 757; (b)
R. G. Cavell, B. Creed, D. J. Law, A. P. Nicola, A. R. Sanger and
A. Somogyvary, US. Pat. Appl., US 447887, 1996.
8 R. G. Cavell and K. V. Katti, US. Pat. Appl., US 752348, 1994.
9 (a) A. Arques, D. Aunon and P. Molina, Tetrahedron Lett., 2004,
45, 4337; (b) We note that the application of iminophospho-
rane–phosphine ligands in the palladium catalyzed cross coupling
of secondary amines with aryl halides has also been briefly
For crystallographic data in CIF or other electronic format
see DOI: 10.1039/b606781f
´
commented on: P. Molina, A. Arques, A. Garcıa and M. C.
´
Ramırez de Arellano, Tetrahedron Lett., 1997, 38, 7613.
10 T. T. Co, S. C. Shim, C. S. Cho, D.-U. Kim and T.-J. Kim, Bull.
Korean Chem. Soc., 2005, 26, 1359.
Acknowledgements
´
a-Alvarez, S. E. Garcı
11 (a) V. Cadierno, P. Crochet, J. Garcı
´
´
Garrido and J. Gimeno, J. Organomet. Chem., 2002, 663, 32; (b)
a-
We are indebted to the Ministerio de Ciencia y Tecnologıa
´
´
V. Cadierno, P. Crochet, J. Dı
Garrido, J. Gimeno, S. Garcı
Inorg. Chem., 2003, 42, 3293; (c) V. Cadierno, P. Crochet, J. Dı
´
ez, J. Garcı
´
a-Alvarez, S. E. Garcı
´
a-
(MCyT) of Spain (Project BQU2003-00255) and the Gobierno
del Principado de Asturias (Project PR-01-GE-6) for financial
support. P. C. and V. C. thank the MCyT and the European
´
a-Granda and M. A. Rodrı
´
guez,
´
ez,
´
J. Garcı
J. Gimeno and M. A. Rodrı
L. Boubekeur, S. Ulmer, L. Ricard, N. Me
Organometallics, 2006, 25, 315.
´
a-Alvarez, S. E. Garcı
´
a-Garrido, S. Garcı
´
a-Granda,
´
guez, Dalton Trans., 2003, 3240; (d)
zailles and P. Le Floch,
Social Fund for ‘‘Ramon y Cajal’’ contracts. M. Z. thanks the
´
´
Ministry of Science and Information Society Technologies
Poland for financial support (Grant No 3T09A 158 29). A.
E. D. A., M. Z. and J. P. M. thank the LEA (Laboratoire
12 (a) M. Zablocka, A. Igau, J.-P. Majoral and K. M. Pietrusiewicz,
Organometallics, 1993, 12, 603; (b) M. Zablocka, B. Delest, A. Igau,
A. Skowronska and J. P. Majoral, Tetrahedron Lett., 1997, 38, 5997.
13 (a) M. Zablocka, F. Boutonnet, A. Igau, F. Dahan, J. P. Majoral
and K. M. Pietrusiewicz, Angew. Chem., Int. Ed. Engl., 1993, 32,
1735; (b) M. Zablocka, A. Igau, N. Cenac, B. Donnadieu, F.
Dahan, J. P. Majoral and M. K. Pietrusiewicz, J. Am. Chem. Soc.,
1995, 117, 8083.
14 For reviews and books covering this field see: (a) C. Bruneau and P.
H. Dixneuf, Chem. Commun., 1997, 507; (b) T. Naota, H. Takaya
and S.-I. Murahashi, Chem. Rev., 1998, 98, 2599; (c) B. M. Trost, F.
D. Toste and A. B. Pinkerton, Chem. Rev., 2001, 101, 2067; (d) T.
M. Trnka and R. H. Grubbs, Acc. Chem. Res., 2001, 34, 18; (e) V.
Ritleng, C. Sirlin and M. Pfeffer, Chem. Rev., 2002, 102, 1731; (f)
Ruthenium in Organic Synthesis, ed. S.-I. Murahashi, Wiley-VCH,
Weinheim, 2004; (g) Ruthenium Catalysts and Fine Chemistry, ed. C.
Bruneau and P. H. Dixneuf, Springer, Berlin, 2004; (h) B. M. Trost,
M. U. Fredericksen and M. T. Rudd, Angew. Chem., Int. Ed., 2005,
44, 6630; (i) C. Bruneau and P. H. Dixneuf, Angew. Chem., Int. Ed.,
2006, 45, 2176; (j) Curr. Org. Chem., 2006, 10, 113–225 (a thematic
issue devoted to ruthenium-catalyzed processes).
Europeen Associe, Toulouse-yod$) for financial support.
´ ´ ´
References
1 See for example: (a) A. Bader and E. Lindner, Coord. Chem. Rev.,
1991, 108, 27; (b) C. S. Slone, D. A. Weinberger and C. A. Mirkin,
Prog. Inorg. Chem., 1999, 48, 233; (c) V. V. Grushin, Chem. Rev.,
2004, 104, 1629.
2 For reviews see: (a) G. R. Newkome, Chem. Rev., 1993, 93, 2067;
(b) P. Espinet and K. Soulantica, Coord. Chem. Rev., 1999,
193–195, 499; (c) P. Braunstein and F. Naud, Angew. Chem., Int.
Ed., 2001, 40, 680; (d) G. Chelucci, G. Orru and G. A. Pinna,
Tetrahedron, 2003, 59, 9471; (e) P. J. Guiry and C. P. Saunders,
Adv. Synth. Catal., 2004, 346, 497; (f) P. Braunstein, J. Organomet.
Chem., 2004, 689, 3953.
3 For reviews see: (a) Y. G. Gololobov, I. N. Zhamurova and L. F.
Kasukhin, Tetrahedron, 1981, 37, 437; (b) Y. G. Gololobov and L.
F. Kasukhin, Tetrahedron, 1992, 48, 1353; (c) A. W. Johnson, in
Ylides and Imines of Phosphorus, Wiley, New York, 1993, p. 403;
(d) P. Molina and M. J. Vilaplana, Synthesis, 1994, 1197; (e) H.
15 H. Staudinger and J. Meyer, Helv. Chim. Acta, 1919, 2, 635.
16 For reviews see: (a) Y. G. Gololobov, I. N. Zhamurova and L. F.
Kasukhin, Tetrahedron, 1981, 37, 437; (b) Y. G. Gololobov and L.
F. Kasukhin, Tetrahedron, 1992, 48, 1353; (c) A. W. Johnson, in
Ylides and Imines of Phosphorus, Wiley, New York, 1993, p. 403.
17 A. V. Kirsanov, Izv. Akad. Nauk. SSSR, 1950, 426.
Wammhoff, G. Richardt and S. Stolben, Adv. Heterocycl. Chem.,
¨
1999, 64, 159; (f) P. M. Fresneda and P. Molina, Synlett, 2004, 1;
(g) A. Arques and P. Molina, Curr. Org. Chem., 2004, 8, 827.
4 For recent references see: (a) H.-R. Wu, Y.-H. Liu, S.-M. Peng and
S.-T. Liu, Eur. J. Inorg. Chem., 2003, 3152; (b) L. P. Spencer, R.
Altwer, P. Wei, L. Gelmini, J. Gauld and D. W. Stephan,
Organometallics, 2003, 22, 3841; (c) J. D. Masuda, P. Wei and
D. W. Stephan, Dalton Trans., 2003, 3500; (d) J. Vicente, J.-A.
´ ´
Abad, R. Clemente, J. Lopez-Serrano, M. C. Ramırez de Arellano,
P. G. Jones and D. Bautista, Organometallics, 2003, 22, 4248; (e)
K. Bernardo-Gusmao, L. F. T. Queiroz, R. F. de Souza, F. Leca,
C. Loup and R. Reau, J. Catal., 2003, 219, 59; (f) K. T. K. Chan,
´
L. P. Spencer, J. D. Masuda, J. S. J. McCahill, P. Wei and D. W.
Stephan, Organometallics, 2004, 23, 381; (g) G. C. Welch, W. E.
Piers, M. Parvez and R. McDonald, Organometallics, 2004, 23,
1811; (h) M. J. Sarsfield, I. May, S. M. Cornet and M. Helliwell,
Inorg. Chem., 2005, 44, 7310; (i) C.-H. Qi, S.-B. Zhang and J.-H.
18 M. A. Bennett, T.-N. Huang, T. W. Matheson and A. K. Smith,
Inorg. Synth., 1982, 21, 74.
19 For reviews on the chemistry of dimers [{RuCl(m-Cl)(Z6-arene)}2]
see: (a) H. Le Bozec, D. Touchard and P. H. Dixneuf, Adv.
Organomet. Chem., 1989, 29, 163; (b) M. A. Bennett, in Compre-
hensive Organometallic Chemistry II, ed. E. W. Abel, F. G. A.
Stone and G. Wilkinson, Pergamon Press, Oxford, 1995, Vol. 7,
p. 549; (c) M. A. Bennett, Coord. Chem. Rev., 1997, 166, 225; (d)
F. C. Pigge and J. J. Coniglio, Curr. Org. Chem., 2001, 5, 757.
20 See for example: (a) C. Larre, B. Donnadieu, A.-M. Caminade
´
and J.-P. Majoral, Eur. J. Inorg. Chem., 1999, 601; (b) M. S.
Balakrishna, R. M. Abhyankar and M. G. Walawalker, Tetrahe-
dron Lett., 2001, 42, 2733; (c) V. Maraval, R. Laurent, B.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1295–1306 | 1305

View Article Online
Donnadieu, A.-M. Caminade and J.-P. Majoral, Synthesis, 2003,
´
29 We note that attempts to promote the selective monooxidation of
the PhP or Ph2P units in the free a-diphosphine 2 by using 1
equivalent of tBuOOH or H2O2 failed. Thus, under different
reaction conditions, unseparable mixtures containing the corre-
´ ´
389; (d) V. Cadierno, J. Dıez, J. Garcıa-Alvarez, J. Gimeno, M. J.
Calhorda and L. F. Veiros, Organometallics, 2004, 23, 2421; (e) V.
´
Cadierno, J. Dı
tallics, 2004, 23, 3425; (f) V. Cadierno, J. Dı
and J. Gimeno, Organometallics, 2005, 25, 2801.
21 V. Cadierno, J. Dıez, S. E. Garcıa-Garrido, S. Garcı
´
ez, J. Garcıa-Alvarez and J. Gimeno, Organome-
´
´
a-Alvarez
´
ez, J. Garcı
´
sponding dioxide (dP (CDCl3) = 25.0 (s, Ph2PQO), 53.6
(s, PhPQO)), phospholane–monooxide (dP (CDCl3) = ꢁ12.9
(d, JPP = 46.1 Hz, Ph2P), 56.3 (d, JPP = 46.1 Hz, PhPQO)) and
unreacted 2 (dP (CDCl3) = ꢁ13.5 (d, JPP = 31.5 Hz, Ph2P), ꢁ4.5
(d, JPP = 31.5 Hz, PhP)) were obtained in all cases.
30 For example: J. W. Faller, B. P. Patel, M. A. Albrizzio and
M. Curtis, Organometallics, 1999, 18, 3096, and references cited
therein.
´
´
´
a-Granda and
J. Gimeno, J. Chem. Soc., Dalton Trans., 2002, 1465.
22 See for example: (a) R. E. Clarke and P. C. Ford, Inorg. Chem.,
1970, 9, 227; (b) C. P. Guengerich and K. Schug, J. Am. Chem.
Soc., 1977, 99, 3298; (c) G. S. Ashby, M. I. Bruce, I. B. Tomkins
and R. C. Wallis, Aust. J. Chem., 1979, 32, 1003; (d) M. I. Bruce, T.
W. Hambley, M. J. Liddell, A. G. Swincer and E. R. T. Tiekink,
Organometallics, 1990, 9, 2886; (e) L. Shao, K. Takeuchi, M.
Ikemoto, T. Kawai, M. Ogasawara, H. Takeuchi, H. Kawano
and M. Saburi, J. Organomet. Chem., 1992, 435, 133; (f) M.
31 For a recent review on this topic see: J. W. Faller and J. Parr, Curr.
Org. Chem., 2006, 10, 151.
32 Recent advances in enantioselective Diels–Alder reactions cata-
lyzed by chiral transition-metal complexes are summarized in: D.
Carmona, M. P. Lamata and L. A. Oro, Coord. Chem. Rev., 2000,
200–202, 717.
Hanack, K. Durr, A. Lange, J. O. Barcina, J. Pohmer and E.
¨
Witke, Synth. Met., 1995, 71, 2275.
23 (a) The coordination chemistry of Ph2PCH2P{QN-4-C6F4CN}Ph2
and related bidentate ligands, such as Ph2PCH2P{QN-3,4-C6F4
(CN)2}Ph2, Ph2PCH2P{QN-3,6-C6F4(CN)2}Ph2 or o-Ph2PC6H4P
{QN-4-C6F4CN}Ph2, has been extensively studied by R. G. Cavell
and co-workers, the coordination of the nitrile function never
being observed. See for example: (a) K. V. Katti and R. G. Cavell,
Organometallics, 1989, 8, 2147; (b) K. V. Katti, B. D. Santarsiero,
A. A. Pinkerton and R. G. Cavell, Inorg. Chem., 1993, 32, 5919; (c)
D. J. Law, G. Bigam and R. G. Cavell, Can. J. Chem., 1995, 73,
635; (d) R. W. Reed, B. Santarsiero and R. G. Cavell, Inorg.
Chem., 1996, 35, 4292; (e) J. Li, R. McDonald and R. G. Cavell,
Organometallics, 1996, 15, 1033.
33 For recent references involving (Z6-arene)–Ru(II) complexes see:
(a) D. Carmona, C. Vega, N. Garcıa, F. J. Lahoz, S. Elipe, L. A.
´
Oro, M. P. Lamata, F. Viguri and R. Borao, Organometallics,
2006, 25, 1592; (b) J. W. Faller and P. P. Fontaine, Organometal-
lics, 2005, 24, 4132; (c) A. J. Davenport, D. L. Davies, J. Fawcett
and D. R. Russell, Dalton Trans., 2004, 1481; (d) J. W. Faller and
D. G. D’Alliessi, Organometallics, 2003, 22, 2749; (e) H. Brunner,
F. Henning, M. Weber, M. Zabel, D. Carmona and F. J. Lahoz,
Synthesis, 2003, 1091; (f) J. W. Faller, A. R. Lavoie and B. J.
Grimmond, Organometallics, 2002, 21, 1662; (g) J. W. Faller and
B. J. Grimmond, Organometallics, 2001, 20, 2454; (h) J. W. Faller
and A. R. Lavoie, J. Organomet. Chem., 2001, 630, 17; (i) A. J.
Davenport, D. L. Davies, J. Fawcett and D. R. Russell, J. Chem.
Soc., Perkin Trans. 1, 2001, 1500; (j) J. W. Faller, B. J. Grimmond
and D. G. D’Alliessi, J. Am. Chem. Soc., 2001, 123, 2525; (k) J. W.
Faller and J. Parr, Organometallics, 2000, 19, 1829; (l) J. W. Faller,
X. Liu and J. Parr, Chirality, 2000, 12, 325.
24 See for example: R. L. Cordiner, D. Albesa-Jove, R. L. Roberts, J.
´
D. Farmer, H. Puschmann, D. Corcoran, A. E. Goeta, J. A. K.
Howard and P. J. Low, J. Organomet. Chem., 2005, 690, 4908, and
references cited therein.
25 Note that the priority order to determine the ruthenium config-
uration is: Z6-p-cymene 4 Cl 4 P 4 N.
34 (a) All the catalytic reactions were performed in the presence of
2,6-lutidine (2.5 mol%) acting as a scavenger of acid impurities. (b)
Similar results were obtained in all cases starting from the cationic
species 6, 7, 10, 11 and 13 after treatment with AgSbF6
(1 equivalent per ruthenium).
35 J. M. Birchall, R. N. Haszeldine and M. E. Jones, J. Chem. Soc. C,
1971, 1343.
36 SIR92—A program for crystal structure solution, A. Altomare, G.
Cascarano, C. Giacovazzo and A. Guagliardi, J. Appl. Crystal-
logr., 1993, 26, 343.
26 A possible driving force for the formation of this particular isomer
may be the p-stacking interaction between the two C6F4 units.
27 Note that, although the spatial disposition of the substituents
remains unchanged, the preference orders for the phosphorus atom
change after imination inverting the R/S assignment.
28 We note that, as previously observed in the synthesis of the
bis(iminophosphorane) derivatives 4a–b (see Scheme 1), the imina-
tion of the Ph2P unit by (PhO)2P(QO)N3 requires a considerably
longer reaction time (7 days) when compared to the highly
activated 4-azido-2,3,5,6-tetrafluorobenzonitrile (8 h). Attempts
to accelerate this reaction working under refluxing conditions
resulted in the formation of a non-separable mixture containing
9a and the oxidized complex 12 (see Scheme 4).
37 CRYSTALS, P. W. Betteridge, J. R. Carruthers, R. I. Cooper, K.
Prout and D. J. Watkin, J. Appl. Crystallogr., 2003, 36, 1487.
38 International Tables for X-Ray Crystallography, Kynoch press,
Birmingham, UK, 1974, vol. IV.
ꢀc
This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
1306 | New J. Chem., 2006, 30, 1295–1306