1,3-bis(thiophosphinoyl)indene: A unique and versatile scaffold for original polymetallic complexes

Article abstract of DOI:10.1021/ic200842z

The coordination of tridentate ligands featuring lateral coordination sites prone to acting as bridging ligands was explored with the aim of obtaining original polymetallic species in a straightforward and controlled manner. Accordingly, the 2-indenyliden

Full text of DOI:10.1021/ic200842z

ARTICLE
pubs.acs.org/IC
1,3-Bis(thiophosphinoyl)indene: A Unique and Versatile Scaffold for
Original Polymetallic Complexes
Noel Nebra,† Nathalie Saffon,‡ Laurent Maron,*,§ Blanca MartinꢀVaca,*,† and Didier Bourissou*,†
†Universitꢀe de Toulouse, UPS, LHFA, 118 Route de Narbonne, and CNRS, LHFA UMR 5069, F-31062 Toulouse, France
‡Universitꢀe de Toulouse, UPS, Institut de Chimie de Toulouse, FR2599, 118 Route de Narbonne, F-31062 Toulouse, France
§Universitꢀe Paul Sabatier and INSA, UPS, LPCNO, 135 Avenue de Rangueil, and CNRS, LPCNO UMR 5215, 31077 Toulouse, France
S Supporting Information
b
ABSTRACT: The coordination of tridentate ligands featuring
lateral coordination sites prone to acting as bridging ligands was
explored with the aim of obtaining original polymetallic species
in a straightforward and controlled manner. Accordingly, the
2-indenylidene chloropalladate [{Ind(Ph2PdS)2}PdCl]ꢀ was
found to behave as a k2-C,S bidentate ligand toward metal
fragments, giving access to homo- and heteropolymetallic
complexes. X-ray diffraction analyses reveal the presence of short metalꢀmetal contacts in all of these complexes. Density
functional theory calculations unambiguously substantiate that the metals engage in unusual d8 d8 interactions with a quasi-
3 3 3
perpendicular arrangement of their coordination planes.
Chart 1. Schematic Representation of HꢀX Bond Activation
’ INTRODUCTION
with Pincer Complexes Featuring Noninnocent Pyridine-
Based Ligands
The last 2 decades have witnessed tremendous developments
with pincer complexes.1 The chelating rigid nature of the
involved tridentate ligands imparts a unique balance of stability
versus reactivity, which has allowed for spectacular catalytic
developments in a variety of transformations. In addition, the
ability of the ligand backbone to actively participate in chemical
transformations (so-called noninnocent character) has opened up
new avenues. Particularly remarkable are the pyridine-based ligands
recently developed by Milstein and co-workers. Indeed, metalꢀ
ligand cooperation via aromatization/dearomatization confers a new
functionality to the pincer scaffold, and thanks to this peculiar
shown to give access to original 2-indenylidene pincer complexes
behavior, a variety of HꢀX bonds (X = H, aryl, OR, NR2, etc.)
[{Ind(Ph2PdS)2}PdX] (X = NHCy2, PPh3, Clꢀ; Chart 2).6 The
ability of thiophosphinoyl moieties to act as bridging ligands7
prompted us to investigate the preparation of polymetallic
species from the {Ind(Ph2PdS)2} platform,8 and we report
herein homobimetallic (PdꢀPd), heterobimetallic (PdꢀIr), and
homotrimetallic (PdꢀPdꢀPd) systems. X-ray diffraction ana-
lyses reveal the presence of short metalꢀmetal contacts in all of
these complexes. Density functional theory (DFT) calculations
unambiguously substantiate that the metals engage in unusual
can be activated under mild conditions (Chart 1).2,3
Inspired by these achievements, we became interested in
exploring the coordination properties of tridentate ligands
featuring lateral coordination sites prone to acting as bridging
ligands, such as sulfur atoms. The ability of a unique pincer ligand
to support the coordination of several metals was envisioned to
afford original polymetallic species4 in a straightforward and
controlled manner. The association of several metal centers often
leads to peculiar chemical and photophysical properties that are
relevant to numerous fields including cooperative multicenter
catalysis, materials science, and bioinorganic chemistry. Thor-
ough analysis of the bonding situation via modern analytical
techniques and computational methods is also of great interest,
especially to gain a better understanding of the various types of
metalꢀmetal interactions.
d8 d8 interactions with a quasi-perpendicular arrangement
3 3 3
of their coordination planes.
’ RESULTS AND DISCUSSION
The chloropalladate [{Ind(Ph2PdS)2}PdCl][NHEtiPr2] (1)6a
1
was first reacted with /2 equiv of [PdCl2(PPh3)]2 at room
Over the past few years, our group has investigated the
influence of short donating side arms on the coordination
properties of fluorenyl and indenyl moieties.5,6 In particular,
double CꢀH activation of 1,3-bis(thiophosphinoyl)indene was
temperature in dichloromethane (DCM). After stirring overnight
Received: April 22, 2011
Published: June 07, 2011
r
2011 American Chemical Society
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Chart 2. Preparation of 2-Indenylidene Pincer Complexes by
Double CꢀH Activation of 1,3-Bis(thiophosphinoyl)indene
Figure 1. Ellipsoid drawing (50% probability) of the molecular struc-
ture of 2. For clarity, lattice solvent molecules (three CH2Cl2 molecules
per asymmetric unit) and hydrogen atoms are omitted and the phenyl
groups at phosphorus are simplified.
Scheme 1. Synthesis of the Homobimetallic Complex 2
Starting from the Chloropalladate 1
Chart 3. Representative Examples of Known Palladium-
Containing Polymetallic Complexes Featuring d8 d8
3 3 3
Interactions
and workup, complex 2was isolated in excellent yield as a red powder
(Scheme 1).9 31P NMR spectroscopy indicates dissymmetrization of
the {Ind(Ph2PdS)2} moiety. The two PdS units are no longer
equivalent and resonate in 2 as two doublet signals at 51.0 ppm (J =
3.4 Hz) and 49.4 ppm (J= 18.8 Hz), while a dd signal is found at 28.1
ppm (J = 18.8 and 3.4 Hz) for the PPh3 ligand at palladium. Also
noteworthy is the upfield shift of the 13C NMR resonance signal
associated with C1 (from 104.2 ppm in 1 to 57.6 ppm in 2),
suggesting a change in hybridization from sp2 to sp3.10
Table 1. Selected Geometric Data (Bond Lengths in Ang-
stroms and Angles in Degrees) Determined Experimentally
and Computed at the B3PW91/SDD(Pd,Ir,P,S),6-31G**-
(Other Atoms) Level of Theory for Complexes 2ꢀ4 (M is the
Metal Added to 1)
According to X-ray diffraction analysis (Figure 1), the chloro-
palladate fragment behaves as a bidentate ligand and coordinates
the incoming [PdCl(PPh3)] fragment through C1 and the
adjacent PdS unit. The C1ꢀP1 bond deviates from the mean
indenyl plane by 27° to enable the sulfur atom S1 to bridge the
two palladium centers. Both metal atoms adopt square-planar arrange-
ments that are approximately perpendicular to each other (γ = 88°).
Remarkably, the PdꢀPd distance [2.9848(2) Å] is significantly
shorter than the sum of the van der Waals radii (4.10 Å)11a and
exceeds the sum of the covalent radii (2.78 Å)11b by only 7%.
The geometric features of complex 2 raise the question about
NBO analysisb
PdꢀM
X-ray 2.9848(2) 88
DFT 3.13 88
X-ray 3.0989(4) 96
DFT 2.98 97
X-ray 3.230(2) 100
DFT 3.181 97
γa PdꢀM Wiberg indexes Pd f M M f Pd
2
3
4
0.11
0.13
0.11
42
13
13
30
79
8
the presence of some Pd Pd interaction. The ability of d8
3 3 3
fragments to engage in M M contacts was recognized early
3 3 3
on12 and is currently attracting growing interest. Unsupported
a Mean angle between the coordination planes of the two metals.
d8 d8 interactions have been observed upon the spontaneous
3 3 3
b Delocalization energy in kcal/mol.
association of ML4 fragments,13 but most examples involve short
bridging ligands14 that bring together the metal fragments.
Representative examples of palladium-containing complexes
On the one hand, the PdꢀPd distance in 2 is between those
observed in complexes AꢀC (2.54ꢀ3.19 Å), suggesting the
featuring d8 d8 interactions are depicted in Chart 3.15ꢀ17
3 3 3
Characteristic features of these complexes are the parallel
arrangement of the interacting square-planar d8 fragments and
the short intermetallic distances. As substantiated by computa-
presence of some Pd Pd interaction. On the other hand, the
3 3 3
bridging coordination of the sulfur atom in 2 results in a quasi-
perpendicular arrangement of the two palladium coordination
planes that markedly contrasts with the usual parallel
disposition.19 To gain deeper insight into the bonding situation
in 2, DFT calculations were carried out at the B3PW91/SDD-
(Pd,P,S),6-31G**(other atoms) level of theory.20 The optimized
geometry of 2 fits nicely with that determined experimentally
(Table 1). Close inspection of the molecular orbitals (MOs)
combined with natural bond order (NBO) analyses revealed the
tional studies, the d8 d8 interactions are weakly bonding but
3 3 3
cannot be considered as genuine chemical bonds. They involve
two types of orbital overlaps along the direction perpendicular to
the coordination planes: (i) a repulsive four-electron interaction
between the filled dz2 orbitals of the two fragments and (ii)
attractive donorꢀacceptor interactions between the filled dz2 and
vacant pz orbitals.12b,14e,15b,c,18
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Figure 2. Selected MOs of complex 2.
Figure 3. Simplified ellipsoid drawing (50% probability) of the molec-
ular structure of 3. For clarity, lattice solvent molecules (one and a half
CH2Cl2 molecules per asymmetric unit) and hydrogen atoms are
omitted and the phenyl groups at phosphorus are simplified.
Scheme 2. Synthesis of the Heterobimetallic Complex 3
Scheme 3. Synthesis of the Homotrimetallic Complex 4
presence of a PdꢀPd interaction reminiscent of that occurring in
parallel d8 d8 systems. Among the MOs with strong metal
3 3 3
parentages, two filled orbitals with bonding and antibonding
PdꢀPd character are present (HOMOꢀ8 and HOMOꢀ1,
respectively; Figure 2). In addition, donorꢀacceptor interactions
are found at the second-order perturbation level in the NBO
analysis. The different environments of the two palladium
centers result in a slightly dissymmetric situation (the delocaliza-
tion energies corresponding to Pd1 f Pd2 and Pd2 f Pd1
interactions amount to 42 and 30 kcal/mol, respectively).
Despite the perpendicular arrangement of the two coordination
planes, the palladium-centered orbitals are diffuse enough to
overlap, resulting overall in a weak bonding interaction. Con-
sistently, the PdꢀPd bond order calculated for 2 (Wiberg index =
0.11) is equivalent to that reported for the prototypical parallel
system [(2-phenylpyridine)Pd(μ-OAc)]2 (0.11).15b The pre-
sence of a PdꢀSꢀPd ring critical point in the atom in molecules
(AIM) analysis also supports the existence of a PdꢀPd interac-
tion in complex 2.20
To evaluate the generality of the synthesis and bonding features
of the homobimetallic complex 2, we then targeted a heterobime-
tallic species. The chloropalladate 1 readily and cleanly reacted with
[IrCl(coe)2]2 (coe = cyclooctene) over 2 h at room temperature
to give the PdꢀIr complex 3 (88% isolated yield; Scheme 2).
Dissymmetrization of the {Ind(Ph2PdS)2} skeleton was clearly
apparent from the 31P NMR spectrum (two broad signals are
found at 50.5 and 49.0 ppm for the two PdSside arms) andthe13C
NMR spectrum (C1 and C3 resonate at 57.9 and 124.8 ppm,
respectively). X-ray crystallography substantiated the structural
analogy between 2 and 3 (Figure 3). The carbon atom C1
coordinates to the [Ir(coe)2] fragment and the adjacent sulfur
atom bridges the two metal atoms whose coordination planes are
approximately perpendicular (γ = 96°). A short intermetallic
distance is observed [PdꢀIr = 3.0989(4) Å compared with 4.05
Å for the sum of the van der Waals radii and 2.80 Å for the sum of
the covalent radii].11 As for the homobimetallic complex 2, the
presence of PdꢀIr interaction in 3 was unambiguously corrobo-
rated by DFT calculations.20 The most noticeable difference is the
marked dissymmetry of the donorꢀacceptor interactions in 3: in
line with the higher Lewis basicity of IrI over PdII, the Ir f Pd
interaction (79 kcal/mol) predominates over the Pd f Ir interac-
tion (13 kcal/mol).
Encouraged by these results, we envisioned the preparation of
a trimetallic complex. The chloropalladate 1 was reacted with 1/2
equiv of [PdCl2(PhCN)2] at room temperature in DCM. Over 2
h, the initially orange solution turned to dark red, and complex 4
was isolated in 86% yield after workup (Scheme 3). Extremely
low solubility prevented NMR characterization, but the trime-
tallic structure of 4 was authenticated by X-ray diffraction analysis
(Figure 4). Accordingly, a palladium(II) center is entrapped by
two chloropalladate fragments that both behave as k2-C,S
bidentate ligands and arrange in a cis fashion. The coordination
plane of the central palladium(II) atom forms an angle of ca. 100°
with the outside palladium fragments, which are almost parallel
0
to each other. The Pd1ꢀPd2 and Pd2ꢀPd1 distances [3.231(2)
Å] slightly exceed that of 2 but are actually very similar to that
found in the homobimetallic complex of type C [3.1909(7) Å].17
Here also, DFT calculations were carried out and the presence of
three-center d8ꢀd8ꢀd8 interaction was apparent from the
corresponding MO, NBO, and AIM data.20
’ CONCLUSIONS
Complexes 3 and 4 represent rare examples of heterobimetallic
and trimetallic species featuring d8 d8 interactions,19,21,22
3 3 3
and their straightforward preparation from the chloropalladate
complex 1 substantiates the synthetic potential of pincer complexes
in this perspective. Thanks to the bridging ability of the lateral
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afforded crystals suitable for X-ray diffraction analysis. Mp: 250 °C.
31P{1H} NMR (202.5 MHz, CDCl3): δ 51.0 (d, JP,P = 3.4 Hz),
1
49.4 (d, JP,P = 18.8 Hz), 28.1 (dd, JP,P = 18.8 and 3.4 Hz). H NMR
(500 MHz, CDCl3): δ 8.56 (dd, 3JH,P = 14.5 Hz and 3JH,H = 7.0 Hz, 2H,
3
3
4
HorthoPPh2), 7.94 (dddd, JH,H = 22.5 Hz, JH,H = 12.5 Hz, JH,P
=
7.5 Hz, and 4JH,H = 1.5 Hz, 4H, HmetaPPh2), 7.84 (td, 3JH,H = 7.5 Hz and
5JH,P = 2.0 Hz, 1H, HparaPPh2), 7.74 (ddd, 3JH,P = 12.0 Hz, 3JH,H = 7.0
Hz, and 4JH,H = 1.0 Hz, 6H, HorthoPPh2), 7.68 (td, 3JH,H = 8.0 Hz and
5JH,P = 3.5 Hz, 2H, HparaPPh2), 7.65 (td, 3JH,H = 9.0 Hz and 5JH,P = 1.5
Hz, 1H, HparaPPh2), 7.57ꢀ7.47 (m, 6H, HorthoPPh3), 7.42ꢀ7.39 (m,
3
3
7H, HmetaPPh2 and HparaPPh3), 7.30 (td, JH,H = JH,H = 8.0 Hz and
4JH,P = 2.5 Hz, 6H, HmetaPPh3), 7.19 (d, 3JH,H = 7.5 Hz, 1H, H6), 7.05
(pt, 3JH,H = 3JH,H = 7.5 Hz, 1H, H5), 7.01 (pseudo-t, 3JH,H = 3JH,H = 8.0
3
3
Hz, 1H, H8), 6.94 (td, JH,H = 7.5 Hz and JH,H = 1.0 Hz, 1H, H7).
13C{1H} NMR (125.8 MHz, CDCl3): δ 162.39 (ddd, 2JC,P = 28.1 Hz,
2JC,P = 17.7 Hz, and 2JC,P = 3.6 Hz, C2), 145.41 (ddd, 2JC,P = 18.0 Hz,
3JC,P = 9.6 Hz, and 4JC,P = 2.7 Hz, C4), 140.99 (d pseudo-t, 2JC,P = 10.9
Hz and 3JC,P = 3JC,P = 4.5 Hz, C9), 134.89 (d, 2JC,P = 12.7 Hz, Cortho),
134.60 (d, 3JC,P = 11.3 Hz, CmetaPPh3), 134.38 (d, 4JC,P = 2.9 Hz, Cpara),
Figure 4. Simplified ellipsoid drawing (50% probability) of the molec-
ular structure of 4. For clarity, lattice solvent molecules (three CH2Cl2
molecules per asymmetric unit) and hydrogen atoms are omitted and
the phenyl groups at phosphorus are simplified.
4
2
133.65 (d, JC,P = 3.1 Hz, Cpara), 132.86 (d, JC,P = 11.6 Hz, Cmeta),
thiophosphinoyl donating groups, a unique SꢀCꢀS tridentate
3
1
132.60 (d, JC,P = 11.4 Hz, Cmeta), 132.64 (d, JC,P = 65.5 Hz, Cipso),
132.51 (d, 4JC,P = 2.9 Hz, Cpara), 132.33 (d, 4JC,P = 3.0 Hz, Cpara), 130.96
(d, 4JC,P = 2.6 Hz, CparaPPh3), 130.14 (d, 1JC,P = 81.5 Hz, Cipso), 129.86
platform supports the coordination of two metals, leading to
original d8 d8 interactions between quasi-perpendicular metal
3 3 3
fragments. Ongoing studies aim at taking advantage of the mod-
ularity of this strategy to prepare a variety of such polymetallic
species. The influence of their peculiar structure on their properties
and reactivity is also under investigation.
3
1
(d, JC,P = 11.4 Hz, Cmeta), 129.76 (d, JC,P = 62.2 Hz, CipsoPPh3),
129.75 (d, 4JC,P = 50.3 Hz, Cipso), 129.66 (d, 2JC,P = 12.7 Hz, Cortho),
129.46 (d, 2JC,P = 13.1 Hz, Cortho), 129.19 (d, 2JC,P = 13.1 Hz, Cortho),
2
3
128.81 (d, JC,P = 12.6 Hz, Cmeta), 128.75 (d, JC,P = 11.1 Hz,
CorthoPPh3), 126.09 (1JC,3P = 83.4 Hz, Cipso), 125.12 (C5), 124.95
1
3
(ddd, JC,P = 131.4 Hz, JC,P = 13.7 Hz, and JC,P = 1.0 Hz, C3),
’ EXPERIMENTAL SECTION
1
121.75 (C7), 121.40 (C6), 118.34 (C8), 57.65 (ddd, JC,P = 81.1 Hz,
2JC,P = 63.8 Hz, and 3JC,P = 17 Hz, C1). Calcd for C51H40ClP3PdS2: C,
56.06; H, 3.60; S, 5.87. Found: C, 55.91; H, 3.73; S, 5.57. HRMS (ESI).
Calcd for 2 (C51H39Cl2P3Pd2S2): 1089.9153. Calcd for [M ꢀ Cl]þ
(C51H39ClP3Pd2S2): 1054.94641. Found: 1054.9490.
General Considerations. All reactions and manipulations were
carried out under an atmosphere of dry argon using standard Schlenk
techniques. Dry, oxygen-free solvents were employed. All organic reagents
were obtained from commercial sources and used as received.
[Pd(PhCN)2Cl2] and [IrCl(coe)2]2 were purchased from STREM.
[Pd(PPh3)Cl2]2,23 {PdCl[IndH(Ph2PdS)2]},6 and {PdCl[Ind(Ph2-
PdS)2]}(iPr2EtNH)6 were prepared according to literature procedures.
31P, 1H, and 13C NMR spectra were recorded on Bruker Avance 300 or 400
and AMX500 spectrometers. 31P, 1H, and 13C chemical shifts are expressed
with a positive sign, in parts per million, relative to external 85% H3PO4 and
Me4Si. Unless otherwise stated, NMR spectra were recorded at 293 K. The
N values corresponding to 1/2(JAX þ JBX) are provided when second-
order ABX systems are observed in the 13C NMR spectra.24
Synthesis of the Homobimetallic Pincer Complex {Pd[Ind-
(Ph2PdS)2]PdCl(PPh3)} (2). Method A: Complex {PdCl[Ind-
(Ph2PdS)2]}[NHEtiPr2] (1) was generated in situ by the reaction of
{PdCl[IndH(Ph2PdS)2]} (56.5 mg, 0.08 mmol) and NEtiPr2 (14 μL,
0.08 mmol) in tetrahydrofuran (THF; 10 mL) at ꢀ78 °C. After stirring
at this temperature for 2 h, [PdCl2(PPh3)]2 (35.9 mg, 0.04 mmol) in
CH2Cl2 (20 mL) was added, and the reaction mixture was stirred
overnight at room temperature. A precipitate was formed by the addition
of pentane (40 mL). A dark-red solid was isolated after filtration and
drying under vacuum for 1 h. THF (15 mL) was added at 0 °C, and the
ammonium salts were removed by filtration. Complex 2 was isolated as a
red powder after the solvent was removed under vacuum. Method B:
An orange suspension containing {PdCl[IndH(Ph2PdS)2]} (56.5 mg,
0.08 mmol), [PdCl2(PPh3)]2 (35.9 mg, 0.04 mmol), and 1.5 equiv of
polystyrene-supported diisopropylethylamine (PS-DIEA; 42 mg, 0.12
mmol) in CH2CL2 (20 mL) was stirred overnight at room temperature.
Synthesis of the Heterobimetallic Pincer Complex {Pd[Ind-
(Ph2PdS)2]Ir(coe)2} (3). Method A: Complex 1 was generated in situ
by the reaction of {PdCl[IndH(Ph2PdS)2]} (56.5 mg, 0.08 mmol) and
NEtiPr2 (14 μL, 0.08 mmol) in THF (10 mL) at ꢀ78 °C. After stirring at
this temperature for 2 h, [IrCl(coe)2]2 (27.7 mg, 0.04 mmol) in CH2Cl2
(20 mL) was added and the reaction mixture was stirred overnight at room
temperature. An orange solid was obtainedafter precipitation with pentane
(40 mL), filtration, and drying under vacuum for 1 h. THF (15 mL) was
added at 0 °C, and the ammonium salts were removed by filtration.
Complex 3 was isolated as a red powder from the supernatant,
after the solvent was removed under vacuum. Method B: An orange
suspension containing {PdCl[IndH(Ph2PdS)2]} (56.5 mg, 0.08 mmol),
[IrCl(coe)]2 (27.7 mg, 0.04 mmol), and 1.5 equiv of PS-DIEA (42 mg,
0.12 mmol) in CH2Cl2 (15 mL) was stirred at room temperature for 2 h.
The PS-DIEA HCl ammonium salts were removed by filtration. Pentane
3
(60 mL) was added to induce precipitation. Complex 3 was isolated as a
red powder (79.2 mg, 88%) after filtration, washing with pentane (3 ꢁ
20 mL), and drying under vacuum. The slow diffusion of pentane (40 mL)
into a CH2Cl2 solution of 3 (20mL) at room temperature afforded crystals
suitable for X-ray diffraction analysis. Mp: 346 °C (dec). 31P{1H} NMR
1
(202.5 MHz, CDCl3): δ 50.6 (br), 49.0 (br). H NMR (500 MHz,
CDCl3): δ 8.74 (dd, 3JH,P = 13.0 Hz and 3JH,H = 7.5 Hz, 2H, HorthoPPh2),
4
8.08 (dd, JH,P = 11.5 Hz and 3JH,H = 7.0 Hz, 2H, HmetaPPh2), 7.82 (t,
3JH,H = 6.5 Hz, 1H, HparaPPh2), 7.70ꢀ7.61 (m, 5H, 2HorthoPPh2,
2HmetaPPh2, and HparaPPh2), 7.54 (br, 4H, 2HorthoPPh2 and 2HparaPPh2),
7.43 (pseudo-t, 3JH,H = 3JH,P = 6.6 Hz, 2H, 2HorthoPPh2), 7.33 (pseudo-t,
The PS-DIEA HCl ammonium salts were removed by filtration.
3
3
3JH,H = JH,H = 7.0 Hz, 2H, 2HmetaPPh2), 7.04 (br, 4H, H5, H8, and
Pentane (60 mL) was added to induce precipitation of 2. Complex 2
was isolated as a red powder (87.5 mg, 98%) after filtration, washing with
pentane (3 ꢁ 20 mL), and drying under vacuum. The slow diffusion of
Et2O (40 mL) into a CH2Cl2 solution of 2 (20 mL) at room temparature
2HmetaPPh2), 6.80 (pt, 3JH,H = 3JH,H = 6.5 Hz, 1H, H6), 6.64 (d, 3JH,H = 6.0
Hz, 1H, H7), 3.59(d, 3JH,H =8.5Hz, 1H, dCH), 3.50(m, 1H, dCH), 3.13
(m, 2H, dCH), 2.45 (br, 1H, CH2), 2.39 (d, JH,H = 15.0 Hz, 1H, CH2),
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2.24 (d, JH,H = 13.0 Hz, 1H, CH2), 1.86 (br, 1H, CH2), 1.80 (d, JH,H = 13.0
Hz, 2H, CH2), 1.71 (br, 1H, CH2), 1.52 (br, 4H, CH2), 1.41 (br, 4H,
CH2), 1.28 (br, 2H, CH2), 1.10 (br, 3H, CH2), 0.81 (br, 4H, CH2).
13C{1H} NMR (125.8 MHz, CDCl3): δ 154.91 (ABX system, J = 20.8 Hz,
0.80 ꢁ 0.50 ꢁ 0.02 mm3, 76 301 reflections collected (13 989 indepen-
dent, Rint = 0.0407), 706 parameters, 105 restraints, R1 [I > 2σ(I)] =
0.0265, wR2 [all data] = 0.0661, largest difference peak and hole 0.533
and ꢀ0.529 e/Å3.
C2), 146.30 (dd, 2JC,P = 18.6 Hzand 3JC,P = 6.6 Hz, C4), 137.85 (dd, 2JC,P
=
3: C49H47ClIrP2PdS2 1.5CH2Cl2, M = 1223.36, triclinic, space
3
14.2 and 3JC,P = 10.8 Hz, C9), 137.59 (d, 2JC,P = 61.9 Hz, Cipso), 135.67 (d,
3JC,P = 13.3 Hz, Cortho), 133.94 (d, 4JC,P = 0.5 Hz, Cpara), 133.12 (d, 4JC,P
2.0 Hz, Cpara), 132.35 (Cpara), 132.29 (Cpara), 132.27 (d, 3JC,P = 11.3 Hz,
group P1, a = 11.7880(2) Å, b = 12.6618(2) Å, c = 18.9211(3) Å, R =
91.6460(10)°, β = 106.2320(10)°, γ = 112.5190(10)°, V = 2475.26(7)
Å3, Z = 2, crystal size 0.21 ꢁ 0.12 ꢁ 0.04 mm3, 34 279 reflections
collected (10 041 independent, Rint = 0.0499), 587 parameters, 36
restraints, R1 [I > 2σ(I)] = 0.0342, wR2 [all data] = 0.0803, largest
difference peak and hole 0.976 and ꢀ0.685 e/Å3.
=
3
1
C
meta), 131.95 (d, JC,P = 11.4 Hz, Cmeta), 130.60 (d, JC,P = 82.8 Hz,
C
ipso), 129.32 (d, 1JC,P = 84.0 Hz, Cipso), 129.23 (d, 3JC,P = 10.9 Hz, Cmeta),
2
129.13 (d, JC,P = 13.0 Hz, Cmeta), 128.93 (d, JC,P = 13.0 Hz, 2Cortho),
2
1
4: C66H48Cl2P4Pd3S4 6CH2Cl2, M = 996.41, monoclinic, space
128.81 (d, JC,P = 14.7 Hz, Cortho), 125.40 (d, JC,P = 82.0 Hz, Cipso),
125.25 (C5), 124.80 (dd, 1JC,P = 64.9 Hz and 3JC,P = 12.3 Hz, C3), 121.70
(C7), 120.85 (C6), 117.70 (C8), 69.59 (dCH), 67.18 (dCH), 59.04
3
group C2/c, a = 34.423(7) Å, b = 14.298(3) Å, c = 22.074(4) Å, β =
129.45(3)°, R = γ = 90°, V = 8389(3) Å3, Z = 4, crystal size 0.15 ꢁ 0.05 ꢁ
0.05 mm3, 11 066 reflections collected (6551 independent, Rint = 0.1741),
522 parameters, 187 restraints, R1 [I > 2σ(I)] = 0.0690, wR2 [all data] =
0.1733, largest difference peak and hole 0.928 and ꢀ0.736 e/Å3.
1
3
(dCH), 57.95 (dd, JC,P = 77.5 Hz and JC,P = 15.7 Hz, C1), 54.70
(dCH), 34.69 (CH2), 33.61 (CH2), 32.21 (CH2), 31.32 (CH2), 29.54
(CH2), 29.39 (CH2), 26.70 (CH2), 26.48 (2CH2), 26.33 (CH2), 25.89
(CH2), 25.55 (CH2). HRMS (ESI). Calcd for 3 (C49H52ClIrP2PdS2):
1100.1338. Calcd for [M ꢀ Cl]þ (C49H52IrP2PdS2): 1065.1650. Found:
1065.1647.
’ ASSOCIATED CONTENT
S
Synthesis of the Homotrimetallic Pincer Complex {Pd3[Ind-
(Ph2PdS)2]2} (4). An orange suspension containing {PdCl[IndH-
(Ph2PdS)2]} (56.5 mg, 0.08 mmol), [PdCl2(PhCN)2] (15.8 mg, 0.04
mmol), and PS-DIEA (42 mg, 0.12 mmol) in CH2Cl2 (15 mL) was stirred
Supporting Information. Computational details and
b
crystallographic data (CIF) for compounds 2ꢀ4. This material
is available free of charge via the Internet at http://pubs.acs.org.
at room temperature for 2 h. The PS-DIEA HCl ammonium salts were
’ AUTHOR INFORMATION
3
removed by filtration, and the resulting dark-red solution was cooled to
ꢀ30 °C for 12 h. Dark-red crystals of 4 were isolated (52.1 mg, 86%) after
filtration. Mp: 344 °C (dec). HRMS (ESI). Calcd for 4(C66H48Cl2P4Pd3S4):
1479.8071. Calcd for [M ꢀ Cl]þ (C66H48Cl2P4Pd3S4): 1444.8382.
Found: 1444.8404. Complex 4 is insoluble in all of the typical NMR
solvents, preventing NMR characterization.
Corresponding Author
*E-mail: dbouriss@chimie.ups-tlse.fr. Tel: þ33 (0)5 61 55 77 37.
Fax: þ33 (0)5 61 55 82 04.
’ ACKNOWLEDGMENT
X-ray Crystallography and Data Collection. Crystallographic
data (excluding structure factors) have been deposited to the Cambridge
Crystallographic Data Centre as supplementary publication nos. CCDC
812443 (2), 812444 (3), and 812445 (4). These data can be obtained
free of charge via www.ccdc.cam.uk/conts/retrieving.html (or from the
CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K.; fax (þ44) 1223-
336-033 or e-mail deposit@ccdc.cam.ac.uk).
We are grateful to the CNRS, UPS, and COST action
CM0802 PhoSciNet for financial support of this work. CalMip
(CNRS, Toulouse, France) is acknowledged for calculation
facilities. L.M. thanks the Institut Universitaire de France, and
N.N. thanks the Ministry of Ciencia e Innovaciꢀon of Spain for a
postdoctoral fellowship. This manuscript is dedicated to the
memory of Pascal Le Floch.
The data for compounds 2ꢀ4 were collected on a Bruker-AXS
SMART APEX II diffractometer at temperatures of 173(2) K (2),
193(3) K (3), and 233(4) K (4) using an oil-coated shock-cooled crystal
with graphite-monochromated Mo KR radiation (wavelength =
0.710 73 Å) by using j and ω scans. The data were integrated with
SAINT, and an empirical absorption correction with SADABS was
applied.25,26 The structures were solved by direct methods (SHELXS-
97),27 and refined against all data by the full-matrix least-squares
methods on F2 (SHELXL-97).28 All non-hydrogen atoms were refined
with anisotropic displacement parameters. The hydrogen atoms were
refined isotropically on calculated positions using a riding model, with
their Uiso values constrained to 1.5Ueq of their pivot atoms for terminal
sp3 carbon atoms and 1.2 times for all other carbon atoms. The crystals
of 4 proved extremely unstable out of solution whatever the tempera-
ture. This complicated the X-ray diffraction analysis and explains the low
completeness (91.6%). The optimal temperature for data collection was
found to be 233 K (faster decomposition was observed at room
temperature as well as 193 K). Complexes 2ꢀ4 were obtained as
solvates, and the methylene chloride molecules were disordered. Geo-
metrical restraint (SAME), similar ADP (anisotropic displacement
parameter) restraint (SIMU), and rigid-bond restraint (DELU) have
been used to make the ADP values of the disordered atoms more
reasonable.
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