The first carbodiphosphorane complex with two palladium centers attached to the CDP carbon: Assembly of a single-stranded di-Pd helicate by the PCP pincer ligand C(dppm)2

Article abstract of DOI:10.1021/om2002975

The reaction of the protonated PCP pincer carbodiphosphorane (CDP) complex [PdCl(CH(dppm)₂)]Cl₂ (1) with [PdCl₂(MeCN) ₂] results in the opening of one ring of the pincer structure and affords the betaine [Pd₂Cl₅(CH(dppm)₂)] (2). The [CH(dppm)₂]⁺ ligand forms a five-membered chelate ring with the Pd(1)Cl₂ moiety via the protonated CDP carbon (positively charged) and one phosphine functionality and bridges to the anionic Pd(2)Cl ₃ fragment via the second phosphine phosphorus. The complex is chiral due to a stereocenter at the protonated CDP carbon atom. Treatment of 2 with water effects deprotonation of the CDP carbon, C-H activation at one methylene group, and the coordination of the second Pd to the CDP carbon. The resulting tricyclic complex [Pd₂Cl₃(C(dppm)(Ph₂CHPh ₂))] (3) is the first compound with two Pd centers coordinated to a CDP carbon. Compound 3 forms a single-stranded helicate structure and exhibits two interdependent carbon stereocenters, resulting in only two possible enantiomers. The complexes 2·2CH₂Cl₂ and 3·3CH₂Cl₂ crystallize in the chiral space group P2₁, whereby a spontaneous resolution of the enantiomers occurs in both cases.

Full text of DOI:10.1021/om2002975

NOTE
pubs.acs.org/Organometallics
The First Carbodiphosphorane Complex with Two Palladium Centers
Attached to the CDP Carbon: Assembly of a Single-Stranded di-Pd
Helicate by the PCP Pincer ligand C(dppm)2
Christian Reitsamer,† Walter Schuh,*,† Holger Kopacka,† Klaus Wurst,† Ernst P. Ellmerer,‡ and Paul Peringer†
†Institut f€ur Allgemeine, Anorganische und Theoretische Chemie der Universit€at Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria
‡Institut f€ur Organische Chemie der Universit€at Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria
S Supporting Information
b
ABSTRACT: The reaction of the protonated PCP pincer carbo-
diphosphorane (CDP) complex [PdCl(CH(dppm)2)]Cl2 (1)
with [PdCl2(MeCN)2] results in the opening of one ring of the
pincer structure and affords the betaine [Pd2Cl5(CH(dppm)2)]
(2). The [CH(dppm)2]+ ligand forms a five-membered chelate
ring with the Pd(1)Cl2 moiety via the protonated CDP carbon
(positively charged) and one phosphine functionality and bridges to
the anionic Pd(2)Cl3 fragment via the second phosphine phos-
phorus. The complex is chiral due to a stereocenter at the
protonated CDP carbon atom. Treatment of 2 with water effects deprotonation of the CDP carbon, CÀH activation at one methylene
group, and the coordination of the second Pd to the CDP carbon. The resulting tricyclic complex [Pd2Cl3(C(dppm)(Ph2CHPh2))] (3) is
the first compound with two Pd centers coordinated to a CDP carbon. Compound 3 forms a single-stranded helicate structure and exhibits
two interdependent carbon stereocenters, resulting in only two possible enantiomers. The complexes 2 2CH2Cl2 and 3 3CH2Cl2 crystallize
3
3
in the chiral space group P21, whereby a spontaneous resolution of the enantiomers occurs in both cases.
’ INTRODUCTION
derivative [C(dppm)(Ph2CHPh2)]À including the first CDP
complex with two Pd centers attached to the central carbon.
Carbodiphosphoranes (CDPs, C(PR3)2) are formally com-
posed of one carbon atom and two tertiary phosphines.1 In
keeping with recent quantum chemical results,2 the central carbon
of CDPs behaves as a potential four-electron donor and may
interact with one or two Lewis acids, e.g., with one or two protons,
one or two metal centers, or one proton and one metal center.3
Complexes with a CDP/metal ratio of 1/2 have hitherto been
seldom realized: two d10 gold atoms are coordinated by the
CDP carbon in [(AuMe)2C(PMe3)2], [(AuPPh3)2C(PMePh2)2]
Br2,4 and [(AuCl)2C(PPh3)2],5 whereas one d10 gold and one
d8 palladium are attached to the CDP functionality in
[PdAu(Cl)2(C(dppm)2)]Cl.6 Two of these compounds, namely,
[(AuCl)2C(PPh3)2] and [PdAu(Cl)2(C(dppm)2)]Cl, have been
structurally characterized.5,6 All these dinuclear CDP complexes
involve at least one d10 gold center, whose sterically favorable
linear coordination geometry and the ability to form tangential
metallophilic interactions (e.g., d10Àd10 or d10Àd8) may stabilize
the complexes. Wewereinterested inthe potential of CDPs for the
coordination of two non-d10 metal centers in order to probe an
extension of the chemistry of this class of ligands. The complex
[PdCl(CH(dppm)2)]Cl2 (1)7 was chosen as a promising starting
material for this purpose, since it contains one d8-Pd center, and its
potential to form bimetallic complexes has been shown by the
synthesis of [PdAu(Cl)2(C(dppm)2)]Cl.6
’ RESULTS AND DISCUSSION
Synthesis. Treatment of the protonated PCP pincer7 CDP
complex[PdCl(CH(dppm)2)]Cl2 (1)8 with [PdCl2(MeCN)2] in
CH2Cl2 results in the opening of one five-membered ring of the
pincer system and produces the dinuclear palladium complex
[Pd2Cl5(CH(dppm)2)] (2) according to Scheme 1 in almost
quantitative yield. The two MeCN ligands of [PdCl2(MeCN)2]
are substituted by one phosphine donor of the [CH(dppm)2]+
ligand and one ClÀ. The ring-opening reaction may be initiated by
ClÀ attack at the pincer complex 1, forming a pentacoordinated
palladium intermediate, followed by the dissociation of one
phosphine function, which is in turn coordinated by the second
Pd center.9 The protonated CDP functionality carries a positive
charge, whichiscompensatedwithinthecomplexbythenegatively
charged PdCl3 group in a betaine-type fashion. The complex is
chiral due to a stereocenter at the protonated CDP carbon atom.
Upon reaction of 2 with water, two ClÀ ligands are substituted by
two carbon centers with concomitant liberation of two equivalents
of HCl. The product [Pd2Cl3(C(dppm)(Ph2CHPh2))] (3) is
composed of the hitherto unknown CDP ligand [C(dppm)(Ph2-
CHPh2)]À and two palladium and three chlorine atoms
In this paper we report on two homodinuclear palladium
Received: April 6, 2011
Published: July 07, 2011
complexes of [CH(dppm)2]+ and the hitherto unknown
r
2011 American Chemical Society
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Organometallics
NOTE
Scheme 1
Figure 2. Thermal ellipsoid plot of 3 3CH2Cl2. The phenyl groups except
3
for the ipso carbon atoms are omitted for clarity. Selected distances (Å) and
angles (deg): Pd(1)ÀC(1) 2.145(3), Pd(1)ÀP(1) 2.2480(9), Pd(1)ÀCl-
(1) 2.3502(9), Pd(1)ÀCl(2) 2.3657(8), Pd(1)ÀPd(2) 3.0951(5), Pd-
(2)ÀC(1) 2.088(3), Pd(2)ÀC(2) 2.177(3), Pd(2)ÀP(4) 2.2905(8),
Pd(2)ÀCl(3) 2.3556(9), P(2)ÀC(1) 1.776(3), P(3)ÀC(1) 1.763(3),
P(1)ÀC(2) 1.782(3), P(2)ÀC(2) 1.762(3), P(3)ÀC(3) 1.808(3), P-
(4)ÀC(3) 1.842(3), C(1)ÀPd(1)ÀP(1) 87.81(8), C(1)ÀPd(1)ÀCl(1)
174.89(9), P(1)ÀPd(1)ÀCl(1) 88.62(3), C(1)ÀPd(1)ÀCl(2) 94.57(8),
P(1)ÀPd(1)ÀCl(2) 172.55(3), Cl(1)ÀPd(1)ÀCl(2) 89.43(3), C(1)À
Pd(2)ÀC(2) 74.33(12), C(1)ÀPd(2)ÀP(4) 91.86(9), C(2)ÀPd(2)ÀP-
(4) 166.19(9), C(1)ÀPd(2)ÀCl(3) 171.51(9), C(2)ÀPd(2)ÀCl(3)
97.32(9), P(4)ÀPd(2)ÀCl(3) 96.49(3), P(3)ÀC(1)ÀP(2) 125.39
(18), P(3)ÀC(1)ÀPd(2) 110.69(15), P(2)ÀC(1)ÀPd(2) 89.23(13),
P(3)ÀC(1)ÀPd(1) 121.87(15), P(2)ÀC(1)ÀPd(1) 105.84(15), Pd-
(2)ÀC(1)ÀPd(1) 93.96(12).
activation reactions in complexes of Pd, Pt, and Rh with the CDP
ligand C(PPh3)2 concern the phenyl groups and afford CCC
pincer complexes, if two phenyl rings are orthometalated.12À14
The CDP and the methine carbon atoms in 3 are stereogenic, and
in view of their interdependence, which is caused by the tricyclic
ring system, only two enantiomers are expected.
Figure 1. Thermal ellipsoid plot of 2 2CH2Cl2. The phenyl groups except
3
for the ipso carbon atoms are omitted for clarity. Selected distances (Å) and
angles (deg): Pd(1)ÀC(1) 2.115(8), Pd(1)ÀP(1) 2.241(2), Pd(1)ÀCl-
(1) 2.311(2), Pd(1)ÀCl(2) 2.375(2), Pd(2)ÀP(4) 2.227(2), Pd(2)ÀCl-
(5) 2.273(3), Pd(2)ÀCl(4) 2.280(3), Pd(2)ÀCl(3) 2.359(3), P(2)À
C(1) 1.786(9), P(3)ÀC(1) 1.806(8), C(1)ÀPd(1)ÀP(1) 92.4(2), C-
(1)ÀPd(1)ÀCl(1) 177.3(2), P(1)ÀPd(1)ÀCl(1) 90.21(9), C(1)ÀPd-
(1)ÀCl(2) 87.5(2), P(1)ÀPd(1)ÀCl(2) 168.93(10), Cl(1)ÀPd(1)À
Cl(2) 90.07(9), P(4)ÀPd(2)ÀCl(5) 90.54(11), P(4)ÀPd(2)ÀCl(4)
89.77(9), Cl(5)ÀPd(2)ÀCl(4) 176.84(19), P(4)ÀPd(2)ÀCl(3)
179.99(13), Cl(5)ÀPd(2)ÀCl(3) 89.45(13), Cl(4)ÀPd(2)ÀCl(3)
90.24(11), H(1)ÀC(1)ÀP(2) 106(5), H(1)ÀC(1)ÀP(3) 104(4), P-
(2)ÀC(1)ÀP(3) 119.9(5), H(1)ÀC(1)ÀPd(1) 109(5), P(2)ÀC-
(1)ÀPd(1) 103.6(4), P(3)ÀC(1)ÀPd(1) 113.2(4).
Crystallography. The complexes 2 2CH2Cl2 and 3 3CH2Cl2
3
3
crystallize in the chiral space group P21, whereby a spontaneous
resolution of the enantiomers occurs in both cases. The enantio-
mers with the absolute CIP configuration C(1) R (2 2CH2Cl2
3
and 3 3CH2Cl2) and C(2) R (3 3CH2Cl2) have been investi-
3
3
gated by SCD. No substantial interaction with the cocrystallized
solvent molecules has been detected in both structures.
In2 2CH2Cl2 (Figure1) the coordination spheres of Pd(1) and
3
Pd(2) are quadratic planar (sum of angles around Pd(1): 360.2°;
sum of angles around Pd(2): 360.0°). The environment around
C(1) is distorted tetrahedral (angles ranging from 103.6(4)° for
P(2)ÀC(1)ÀPd(1) to 119.9(5)° for P(2)ÀC(1)ÀP(3); sum of
angles around C(1) including Pd(1), P(2), and P(3): 336.7°). The
five-membered ring Pd(1)P(1)C(2)P(2)C(1) displays an envel-
ope conformation with P(2) at the flap; the bridging arm of the
ligand backbone consisting of C(1)P(3)C(3)P(4) adopts a zigzag
chain structure. The Pd(1)ÀC(1) distance (2.115(8) Å) as well as
the P(2)ÀC(1)ÀP(3) angle (119.9(5)°) are very similar to the
respective values in the protonated pincer CDP complex 1
(2.102(2) Å and 121.9(2)°).7 The PÀC distances (P(2)ÀC(1)
1.786(9), P(3)ÀC(1) 1.806(8) Å) indicate PÀC single bonds, as
do those of 1 (P(2)ÀC(1) 1.804(3), P(3)ÀC(1) 1.801(3) Å).
The PdÀP distances are in a narrow range (2.227(2)À2.241(2) Å),
whereas the PdÀCl distances show substantial dependence on the
(Scheme 1). The tricyclic structure incorporates a PCC pincer
substructure consisting of a four-membered PdCPC ring and a
five membered PdPCPC ring. The CDP complex 3 is the first
example where the central carbon acts as a donor toward two
metals without the involvement of gold.
The reaction is thought to be initiated by the deprotonation of
the protonated CDP carbon atom C(1) of 2 in view of a related
reaction of 1 with water resulting in the CDP complex
[PdCl(C(dppm)2)]Cl.7 Subsequent steps—in unknown chron-
ological order—comprise the coordination of the second Pd
center at the CDP carbon and the cyclometalation at one
methylene group, resulting in the formation of a tricyclic
structure.10 The CH activation of the methylene group of
coordinated dppm ligands is not uncommon, and predominantly
coinage metals were attached to the carbon center.11 Other CH
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Organometallics
NOTE
respective trans-ligand (trans-Cl: 2.273(3)À2.280(3) Å; trans-C:
2.311(2) Å; trans-P: 2.359(3)À2.375(2) Å).
cases. Distances similar to the mean (2.117 Å) are observed for
related complexes in which two Lewis acids interact with the
CDP carbon center: 2.115(8) Å for 1, in which the CDP carbon
atom interacts with one palladium and one proton, and 2.128(3)
Å observed for [PdAu(Cl)2(C(dppm)2)]Cl, in which a gold and
a palladium center are attached to the CDP carbon.6 A smaller
value of 2.062(2) Å has been reported for the PCP pincer
complex [PdCl(C(dppm)2)]Cl, involving a three-coordinate
central CDP carbon.7 The PdÀC distance in an orthometalated
palladium complex of the CDP ligand C(PPh3)2 is 2.127(7) Å,14
and a similar PdÀC distance (2.120(2) Å) was observed for
a complex of a P-heterocyclic carbodiphosphorane.14 The long-
est PdÀC bond in 3 (2.177(3) Å) connects Pd(2) with the
methine carbon atom C(2). A similar value (2.153(8) Å) has
been reported for a complex involving the substructure PPh2CH-
(Pd)P(O)Ph2.18 The C(1)ÀP distances in 3 amount to 1.776(3)
and 1.763(3) Å, which is close to the values reported for other
CDP complexes in which two metals are attached to the central
carbon: 1.776(3) Å for [(AuCl)2(CPPh3)2]5 and 1.786(3) Å for
[PdAuCl2(C(dppm)2]Cl.6 This is slightly shorter than expected
for PÀC single bonds and indicates a partial delocalization of a
negative charge on the central carbon atom. The same effect also
applies for the cyclometalated dppm fragment of 3, exhibiting
C(2)ÀP distances of 1.782(2) and 1.762(3) Å, compared to the
distinctly longer C(3)ÀP distances (1.808(3) and 1.842(3) Å)
involving the other dppm set including the methylene group. The
axial H atom of the dppm-CH2 group shows a weak intramole-
cular contact toward Cl(2) (H(3a)ÀCl(2) 2.566 Å; C(3)À
H(3a)ÀCl(2) 132°), in line with the observation that dppm
In 3 3CH2Cl2 (Figure 2) the ligand [C(dppm)(Ph2PCHP-
À3
Ph2)] forms a single-stranded helicate wrapped around the two
Pd centers. The screw angle from P(1) along the ligand backbone
to P(4) amounts toca. 180° imposed bythe bridging carbonatom,
leading to approximately orthogonal square-planar coordination
geometries of the Pd centers with a Pd(1)ÀC(1)ÀPd(2) angle of
93.96(12)°. In this context it is interesting to note that compound
3 shows spontaneous resolution of the enantiomers, whereas
single-stranded helicates usually tend to form racemic mixtures in
the solid state; one chiral single-stranded dipalladium helicate has
been synthetized by use of an enantiopure chiral ligand.15
The Pd(1)ÀPd(2) separation of 3.0951(5) Å is within the van
der Waals limit of 3.26 Å;16 however no strong bond is assumed
to be present, in particular since the d8Àd8 interaction in Pd
complexes is generally weaker than for other metals (e.g., Rh, Ir,
Pt).17 The PdÀPd distance and the coordination geometries
might be mainly determined by the rigid ligand backbone so
that a conclusion is difficult. The corresponding Pd(1)ÀC-
(1)ÀPd(2) angle (93.96(12)°) is distinctly smaller than the
value of 98.44(11)° reported for the AuÀCÀAu element in
[C(AuCl)2(PPh3)2], which is not constrained by any cyclic
ligand backbone.5 An even smaller angle was observed for
the cationic complex [PdAuCl2(C(dppm)2)]Cl (86.80(11)°).6
The corresponding intermetallic separations are 3.1432(2)
Å for [C(AuCl)2(PPh3)2]5 and 2.8900(3) Å for [PdAuCl2
(C(dppm)2)]Cl.6 The environment of both Pd(1) and Pd(2)
is planar (sum of angles around Pd(1): 360.4°; around Pd(2):
360.0°). The cis angles involving Pd(1) ranging from 87.81(8)°
to 94.57(8)° show a nearly quadratic coordination geometry,
whereas major distortions around Pd(2), most pronounced in
the C(1)Pd(2)C(2) angle of 74.33(12)°, seem to be caused by
the strain of the four-membered Pd(2)C(1)P(2)C(2) ring. This
might also play a significant role for distortions in the tetrahedral
geometries of the other ring members C(1), C(2), and P(2),
being evident from the relatively small angles of P(2)ÀC-
(1)ÀPd(2) (89.23(13)°), P(2)ÀC(2)ÀPd(2) (86.80(13)°),
and C(2)ÀP(2)ÀC(1) (93.55(14)°). The sum of these inner
angles of the four-membered ring is 343.91°, demonstrating that
the ring is substantially bent. The transannular Pd(2)ÀP(2)
distance in this ring amounts to 2.7229(9) Å and is thought to be
imposed by the geometry of the small ring rather than indicating
any interaction. The arrangement of the atoms surrounding the
CDP carbon C(1) differs markedly from a regular tetrahedral
geometry, as can be seen from the angles around C(1) ranging
from 125.39(18)° for P(3)ÀC(1)ÀP(2) to 89.23(13)° for
P(2)ÀC(1)ÀPd(2). Whereas C(1) is nearly in plane with
P(2), P(3), and Pd(1) according to a sum of angles of 353.1°,
the sum of the angles around C(1) formed with the sets P(2)P-
(3)Pd(2) and Pd(1)Pd(2)P(3) amounts to 325.3° and 326.5°,
corresponding to a tetrahedral geometry. The sum of angles
around C(1) including Pd(1)Pd(2)P(2) is as small as 289.0°.
The five-membered ring Pd(2)C(1)P(3)C(3)P(4) being part of
the PCC pincer substructure exhibits a twist conformation. The
second five-membered ring involving Pd(1) (Pd(1)C(1)P(2)
C(2)P(1)) displays an envelope conformation with the P(2)
atom at the flap. The three PdÀC separations of 3 vary between
2.088(3) and 2.177(3) Å. The distances between the two
palladium centers and the CDP carbon C(1) are significantly
different (2.145(3) Å (Pd(1)) and 2.088(3) Å (Pd(2))),
although there is a diagonal CÀPdÀCl bond sequence in both
and related ligands are capable of acting as CÀH X hydrogen
3 3 3
bond donors.19
NMR Spectroscopy. The 31P chemical shifts of 2 and 3 show
the phosphines at high field (2: 6.0, 10.2 ppm; 3: À3.9, 12.5
ppm) and the phosphoranes at low field (2: 27.7, 15.6 ppm; 3:
31
29.0, 51.5 ppm). The largest 31PÀ P couplings (2: 41 Hz; 3: 49,
56 Hz) are typical for the five-membered ring substructures, in
line with the NMR parameters of the related compounds 1 and
2
[PdAuCl2(C(dppm)2)]Cl.6,7 The J(P2P3) are only small in
both cases (2: 6 Hz; 3: 13 Hz). The P1ÀP4 and P2ÀP4
couplings in 3 display relatively large values (both 16 Hz), which
are attributed to the 3J(PÀPdÀCÀP)trans pathway along Pd2.
1
The H NMR spectrum of 3 shows the methine proton at
highest field (2.59 ppm) and the methylene protons at lower
field. An unusually large chemical shift difference of 2.69 ppm is
observed between the CH2 atoms H3a (6.23 ppm) and H3b
(3.54 ppm). Significantly smaller differences were found in
compounds containing methylene groups, e.g., in cyclohexane
or in metal complexes (Δδ = 0.5À1.5 ppm).20 Moreover it is
interesting to note that metal complexes of dppm and related
ligands show the resonances of equatorial protons at lower field
than the axial ones.20 In contrast to that, an inverted pattern is
observed for the axial H3a (6.23 ppm) and the equatorial H3b
(3.54 ppm) in 3. A tentative explanation for the extreme low-field
resonance of the axial proton in 3 could be its spatial proximity to
the CDP-Pd2 core: A considerable magnetic anisotropy of the
bonding system might account for this striking feature. Further-
more the intramolecular contact of H3a toward Cl2 (see Crystal-
lography section) is also expected to contribute to the
deshielding in the proton NMR spectrum.
The 13C signal of the central carbon atom of 3 shows a chemical
shift at even higher field (À8.8 ppm) than values reported for other
CDP metal complexes derived from C(PPh3)2 (15.13À6.94 ppm).13
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Organometallics
NOTE
’ CONCLUSION
3 3CH2Cl2. This material is available free of charge via the
Internet at http://pubs.acs.org.
3
The formation of compound 3 shows that the ligand C-
(dppm)2 is able to stabilize complexes with two d8-metals at
the CDP carbon, leading to the first example for this class of
ligands. An extended synthetic potential was revealed by CÀH
activation of C(dppm)2, which not only behaves as a PCP ligand
but may form additional bonds to metal centers via the aliphatic
carbons of the dppm subunits.
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(10) A scheme of potential reaction pathways for the formation of 3
is shown in the Supporting Information.
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’ EXPERIMENTAL SECTION
The complexes 17 and [PdCl2(MeCN)2)]21 were prepared byliterature
procedures; all other reagents were obtained from commercial suppliers.
The solvents were not dried. All operations were carried out under
atmospheric conditions. X-ray data were collected on a Nonius Kappa
CCD diffractometer using graphite-monochromated Mo KR radiation (λ
= 0.71073 Å). The structures were solved by direct methods.22
31P, 1H, and 13C NMR spectra were recorded on Bruker DPX 300 and
Avance 600 NMR spectrometers and were referenced against solvent
peaks or external 85% H3PO4. In the NMR data, the atoms are labeled as
in the crystal structures. The 31P resonances of 2 and 3 were assigned on
the basis of the 31P shifts found for 1 as well as by use of the large 2J(PP)
coupling in the five-membered ring.6,7 Additional 31PÀ H correlation
1
experiments were performed, which support the assignments in 3. The
1H resonances in 3 could be unambiguously assigned to the methine and
methylene protons by a 1H{31P} experiment. The axial and equatorial
protons of the CH2 group were assigned due to their different coupling
pattern, in particular due to observation of the favorable long-range
coupling of the equatorial H3b toward P2 along the W-type ligand
backbone. No 1H NMR data could be obtained for 2 due to massive line
broadening at room temperature and immediate precipitation of
2 2CH2Cl2 during cooling experiments. The 13C shifts in 3—in
3
particular the CDP carbon—could be observed only indirectly by use
1
of 13CÀ H correlation due to the limited solubility of this compound.
[Pd2Cl5(CH(dppm)2)] (2): Compound 2 precipitates upon heating
a mixture of PdCl2(MeCN)2 (13.0 mg, 0.05 mmol) and 1 (49.7 mg,
0.05 mmol) in CH2Cl2 (0.5 mL) to 60 °C for 24 h. The brownish
microcrystalline material is separated and dried in vacuo (55 mg, 94%).
(17) Bercaw, J. E.; Durrell, A. C.; Gray, H. B.; Green, J. C.; Hazari,
N.; Labinger, J. A.; Winkler, J. R. Inorg. Chem. 2010, 49, 1801.
(18) Rashidi, M.; Vittal, J. J.; Puddephatt, R. J. J. Chem. Soc., Dalton
Trans. 1994, 1283.
Single crystals of the composition C51H45Cl5P4Pd2 2CH2Cl2 were
3
obtained upon standing of a mixture of PdCl2(MeCN)2 and 1 in
CH2Cl2 at ambient temperature for several days.
31P{1H} NMR (CD2Cl2): δ 6.0 (J(P1P2) = 41, P1), 27.7 (J(P2P3) = 6,
J(P2P4) = 5, P2); 15.6 (J(P3P4) = 5, P3), 10.2 (P4). Anal. Calcd for
C51H45Cl5P4Pd2: C, 52.27; H, 3.87. Found: C, 52.0; H, 3.7.
(19) Jones, P. G.; Ahrens, B. Chem. Commun. 1998, 2307.
(20) (a) Wachtler, H.; Schuh, W.; Augner, S.; H€agele, G.; Wurst, K.;
Peringer, P. Organometallics 2008, 27, 1797. (b) Schuh, W.; H€agele, G.;
Olschner, R.; Lindner, A.; Dvortsak, P.; Kopacka, H.; Wurst, K.;
Peringer, P. J. Chem. Soc., Dalton Trans. 2002, 19. (c) Neve, F.; Ghedini,
M.; Tiripicchio, A.; Ugozzoll, F. Organometallics 1992, 11, 795.
(d) Arsenault, G. J.; Manojlovic-Muir, L.; Muir, K. W.; Puddephatt,
R. J.; Teurnicht, I. Angew. Chem., Int. Ed. Engl. 1987, 26, 86. (e) Hutton,
A. T.; Langrick, C. R.; McEwan, D. M.; Pringle, P. G.; Shaw, B. L. J.
Chem. Soc., Dalton Trans. 1985, 2121. (f) Blagg, A.; Hutton, A. T.;
Pringle, P. G.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1984, 1815. (g)
Puddephatt, R. J.; Azam, K. A.; Hill, R. H.; Brown, M. P.; Nelson, C. D.;
Moulding, R. P.; Seddon, K. R.; Grossel, M. C. J. Am. Chem. Soc. 1983,
105, 5642. (h) Puddephatt, R. J.; Thomson, M. A. Inorg. Chem. 1982,
21, 725. (i) Jensen, F. R.; Noyce, D. S.; Sederholm, C. H.; Berlin, A. J. J.
Am. Chem. Soc. 1960, 82, 1256. (j) Moritz, A. G.; Sheppard, N. Mol. Phys.
1962, 5, 361.
[Pd2Cl3(C(dppm)(Ph2CHPh2))] (3): A mixture of 2 (58.6 mg, 0.05
mmol), CH2Cl2 (0.5 mL), and water (0.5 mL) is stirred for one week. The
solid is separated, washed with CH2Cl2, and dried in vacuo. Yield: 48 mg
(82%). Single crystals of composition C51H43Cl3P4Pd2 3CH2Cl2 were
3
obtained upon layering a supersaturated solution of 2in CH2Cl2 with water.
31P{1H} NMR (CD2Cl2): δ À3.9 (J(P1P2) = 49, J(P1P3) = 3,
J(P1P4) = 16, P1), 29.0 (J(P2P3) = 13, J(P2P4) = 16, P2), 51.5
1
(J(P3P4) = 56, P3), 12.5 (P4). H NMR (CD2Cl2/MeOH) δ 2.59
(J(P1H2) = 9.7, J(P2H2) = 10.5, J(P3H2) = 9.7, J(P4H2) = 4.1, H2),
3.54 (J(H3aH3b) = 14.5, J(P2H3b) = 4.2, J(P3H3b) = 6.2, J(P4H3b) =
9.5, H3b), 6.23 (J(P3H3a) = 19.3, J(P4H3a) = 10.6, H3a), 6.45À8.37
(m, ca. 40H, Ph). 13C{1H} NMR (CD2Cl2/MeOH): δ À8.8 (C1), 6.3
(C2), 34.3 (C3). Anal. Calcd for C51H43Cl3P4Pd2: C, 55.74; H, 3.94.
Found: C, 55.4; H, 3.7.
(21) Andrews, M. A.; Chang, T. C.-T.; Cheng, Ch.-W. F.; Emge,
T. J.; Kelly, K. P.; Koetzle, T. F. J. Am. Chem. Soc. 1984, 106, 5913.
(22) Sheldrick, G. M. SHELXS-86: Program for Crystal Structure
Solutions; Universit€at G€ottingen, 1986. Sheldrick, G. M. SHELXL-97:
Program for Refinement of Crystal Structures; Universit€at G€ottingen, 1997.
’ ASSOCIATED CONTENT
S
Supporting Information. CIF data of 2 2CH2Cl2 and
b
3
3 3CH2Cl2. Schemes of potential reaction pathways for the
3
formation of 2 and 3; crystal data table of 2 2CH2Cl2 and
3
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dx.doi.org/10.1021/om2002975 |Organometallics 2011, 30, 4220–4223