Synthesis and crystal structure of four Pd(II) complexes containing nido or closo carborane diphosphine ligands

Article abstract of DOI:10.1016/j.poly.2006.08.038

Three Pd(II) complexes [Pd₂(μ-Cl)₂{7,8-(PPh₂)₂-7,8-C₂B₉H₁₀}₂] · 0.25CH₂Cl₂ (1), [Pd{7,8-(PPh₂)₂-7,8-C₂B₉H₁₀}₂] · 4CHCl₃ (2) and [PdCl₂(1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀)] (3) have been synthesized by the reactions of 1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀ with PdCl₂ in acetonitrile, cyanophenyl and dichloromethane, respectively. A fourth complex, [PdI₂(1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀)] (4), was obtained by a ligand exchange reaction through the substitution of the Cl^- of complex 3 with I^-. All four complexes have been characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR spectroscopy and X-ray structure determination. Single crystal X-ray determination showed that the carborane cage, nido for 1, 2 and closo for 3, 4, was coordinated bidentately to the Pd atom through the two P atoms, and the geometry at the Pd atom was square-planar in all the complexes.

Full text of DOI:10.1016/j.poly.2006.08.038

Polyhedron 26 (2007) 719–724
www.elsevier.com/locate/poly
Synthesis and crystal structure of four Pd(II) complexes containing
nido or closo carborane diphosphine ligands
*
J.-M. Dou , D.-P. Zhang, D.-C. Li, D.-Q. Wang
Department of Chemistry, Liaocheng University, Liaocheng 252059, PR China
Received 21 July 2006; accepted 31 August 2006
Available online 22 September 2006
Abstract
Three Pd(II) complexes [Pd
2
(l-Cl)
2
{7,8-(PPh
2
)
2
-7,8-C
2
B
9
H
10
}
2
] Æ 0.25CH
2
Cl
2
(1), [Pd{7,8-(PPh -7,8-C
-1,2-C 10 with PdCl
2 10
-1,2-C B H10)] (4), was obtained by a ligand
2
)
2
2
B
9
H
10
}
2
] Æ 4CHCl
3
(2) and
[
PdCl (1,2-(PPh -1,2-C 10)] (3) have been synthesized by the reactions of 1,2-(PPh
2
2
)
2
B
2 10
H
2
)
2
2
B
10
H
2
in acetonitrile,
cyanophenyl and dichloromethane, respectively. A fourth complex, [PdI
2
(1,2-(PPh
2
)
2
ꢀ
ꢀ
exchange reaction through the substitution of the Cl of complex 3 with I . All four complexes have been characterized by elemental
1
13
analysis, FT-IR, H and C NMR spectroscopy and X-ray structure determination. Single crystal X-ray determination showed that
the carborane cage, nido for 1, 2 and closo for 3, 4, was coordinated bidentately to the Pd atom through the two P atoms, and the geom-
etry at the Pd atom was square-planar in all the complexes.
ꢀ
2006 Elsevier Ltd. All rights reserved.
ꢀ
2 2 2 10 2 2 2 9 10
Keywords: Synthesis and crystal structure; Pd(II) complexes; 1,2-(PPh ) -1,2-C B H10; [7,8-(PPh ) -7,8-C B H ]
1
. Introduction
Bidentate ligands have played an important role in the
between the ligand and a metal atom. Several Pd(II) com-
plexes with closo or nido carborane diphosphine ligands,
such as [PdCl (1,2-(PPh ) -1,2-C B H )] Æ CH Cl [5],
2
2 2
2
10 10
2
2
development of catalytic applications of metal organic com-
plexes [1]. Two of the fundamentals for these catalysts are
that two cispositions of the metal center are available to per-
form the reaction, and bidentate phosphines have already
been demonstrated to be very convenient for this sort of
catalysis [2]. The influence of substitution at the cluster
carbon atoms in o-carborane by electron rich element phos-
phorus has been of interest to us. Among of the derivatives
of o-carborane, the closo diphosphine 1,2-(PPh ) -1,2-
[PdClMe(1,2-(PPh ) -1,2-C B H )] Æ CH Cl [6], [PdBr1.133-
2 2 2 10 10 2 2
Cl0.867(1,2-(PPh ) -1,2-C B H )] Æ CH Cl ,
[PdBr (1,2-
2
2 2
2
10 10
2
2
(PPh ) -1,2-C B H )] Æ CH Cl and [PdBrCl0.541Me0.459
-
2
2
2
10 10
2
2
(1,2-(PPh ) -1,2-C B H )] Æ CHCl [7], where the struc-
2
2
2
10 10
3
tures have been characterized by X-ray diffraction, have
been reported. Considering the importance of Pd as a metal
in catalysis, we are also interested in this kind of complex
and reported a Pd(II) complex with the formula [PdCl-
(PPh ){7,8-(PPh ) -7,8-C B H }] Æ 1.25CH Cl [8]. Recently,
2
ꢀ
2
3
2 2
2
9
10
2
2
C B H and the nido [7,8-(PPh ) -7,8-C B H ] anion
we investigated the reactions of the closo diphosphine
2
10 10
2 2
2
9
10
degraded from the closo species are two typical bidentate
phosphine ligands [3,4]. Because the two phosphorus atoms
bonded to the two adjacent carbon atoms of the o-carbo-
rane are fixed by the geometry of the carborane skeleton
in an eclipsed conformation at cis positions, a stable com-
plex can be formed through a five-membered chelating ring
ligand with PdCl in three different solvents and obtained
2
three Pd(II) complexes with the formula [Pd (l-Cl) {7,8-
2
2
(PPh ) -7,8-C B H } ] Æ 0.25CH Cl (1), [Pd{7,8-(PPh ) -
2
2
2
9
10 2
2
2
2 2
7,8-C B H } ] Æ 4CHCl (2) and [PdCl (1,2-(PPh ) -1,
2
9
10 2
3
2
2 2
2-C B H )] (3). By using a ligand exchange reaction, we
2
10 10
have also obtained the complex [PdI (1,2-(PPh ) -1,
2
2 2
2
-C B H )] (4). All the complexes were characterized by
2 10 10
1
13
*
elemental analysis, FT-IR, H and C NMR spectroscopy
and X-ray structure determination.
Corresponding author. Tel.: +86 635 8239069.
E-mail address: jmdou@lctu.edu.cn (J.-M. Dou).
0
277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.08.038

720
J.-M. Dou et al. / Polyhedron 26 (2007) 719–724
2
. Experimental
2.2.3. Preparation of [PdCl (1,2-(PPh ) -1,2-C B H )]
2 2 2 2 10 10
(
3)
2
.1. Reagents and techniques
PdCl (18.8 mg, 0.10 mmol) was added to a solution of
2
1
,2-(PPh ) -1,2-C B H (51.2 mg, 0.10 mmol) in 10 ml
2
2
2 10 10
All the reactions were carried out under an atmo-
dichloromethane. The mixture was refluxed for 3 h under
sphere of dry, oxygen-free dinitrogen. Some subsequent
manipulations were performed in the air. Solvents were
dried with suitable drying agents, distilled under dinitro-
gen and deoxygenated prior to use. 1,2-(PPh ) -1,2-
the protection of dry N , and concentrated to 5 ml, and
2
then 20ml n-hexane was added to precipitate the solid.
Yield: 53.8 mg, 78.0%. M.p. 291–292 ꢁC. A crystal suitable
for X-ray diffraction was obtained from a CH Cl solution
2
2
2
2
ꢀ
1
C B H
was prepared according to the literature
after partial evaporation the solvent. FT-IR m
3000 m, 2600 m, 1433 m, 1080 m, 755 m. H NMR
(cm ):
2
10 10
KBr
1
procedure [3]. All chemicals were purchased and used
as received. Infrared spectra were recorded in the range
1
3
(400.15 MHz, CDCl ): 7.2–7.6 ppm (20H);
C NMR
3
ꢀ
1
4
00–4000 cm
from KBr pellets on a Nicolet-460 FT-
(100.63 MHz, CDCl ): 124–132 ppm (24C), 76.3 ppm
3
IR spectrophotometer. Elemental analysis (C, H) was
carried out with a Perkin–Elemer 2400 II elemental ana-
lyzer. The H and C NMR were recorded on a Varian
(2C). Anal. Calc. for C H B Cl P Pd: C, 45.26; H,
4.38; Found: C, 45.40; H, 4.32%.
2
6
30 10
2 2
1
13
Mercury 400 spectrometer in CDCl solution with tetra-
2.2.4. Preparation of [PdI (1,2-(PPh ) -1,2-C B H )]
2
3
2 2
2 10 10
methylsilane (TMS) as an internal standard at 400.15
(4)
1
3
and 100.63 MHz, respectively. The
C spectra are
KI (1.0 mmol, 166 mg) was added to the dichlorometh-
ane solution obtained from the preparation of complex 3.
The suspension was refluxed for 5 h under the protection
broadband proton decoupled. The chemical shifts are
reported in parts per million with respect to the refer-
1
ences and are stated relative to external TMS for
and C NMR.
H
of dry N , and then filtered. The yellow filtrate was concen-
2
1
3
trated to 5 ml, and 20 ml n-hexane was added to precipitate
the solid. Yield 43.2 mg, 49.5%. M.p. 261–262 ꢁC. A crystal
suitable for X-ray diffraction was obtained from a
2
2
.2. Synthetic procedures
ꢀ
1
dichloromethane–n-hexane solution. FT-IR m
3
(cm ):
KBr
1
030 m, 2590 m, 1445 m, 1090 m, 727 m. H NMR
.2.1. Preparation of [Pd (l-Cl) {7,8-(PPh ) -7,8-
2
2
2 2
13
(
(
(
400.15 MHz, CDCl ): 7.2–7.6 ppm (20H);
C NMR
3
C B H } ] Æ 0.25CH Cl (1)
2
9
10 2
2
2
100.63 MHz, CDCl ): 125–133 ppm (24C), 77.3 ppm
2C). Anal. Calc. for C H B I P Pd: C, 35.78; H, 3.47;
3
PdCl2 (18.8 mg, 0.10 mmol) and 1,2-(PPh ) -1,2-
2 2
2
6
30 10 2 2
C B H
(51.2 mg, 0.10 mmol) were added to 10 ml
2
10 10
Found: C, 35.60; H, 3.38%.
acetonitrile and the mixture was refluxed for 6 h under
the protection of dry N . The yellow solid that formed
2
2
.3. X-ray crystallography data collection and processing
was filtered off, washed with acetonitrile, and dried in
vacuum (26.4 mg, 41.0%). M.p. 278–279 ꢁC. A crystal
suitable for X-ray diffraction was obtained from a
The collection of crystallographic data for the four com-
ꢀ
1
plexes was carried out on a Bruker Smart-1000 CCD dif-
fractometer, using graphite-monochromatized Mo-Ka
radiation (k = 0.71073 A) at 298(2) K. The structures were
solved by direct method and expanded using Fourier differ-
ence techniques with the SHELXTL-97 program package [9].
The solvent CH Cl in complex 1 was disordered and par-
tially occupied atoms were refined with isotropic displace-
ment parameters, whilst the remaining non-hydrogen
atoms were refined anisotropically by full-matrix least-
dichloromethane–n-hexane solution. FT-IR m
3
(cm ):
KBr
1
052 m, 2540 m, 1435 m, 1098 m, 741 m. H NMR
˚
1
3
(
400.15 MHz, CDCl ): ꢀ2.1 ppm (2H, B–H–B);
C
3
NMR (100.63 MHz, CDCl ): 124–131 ppm (48C),
3
7
6.5 ppm (4C). Anal. Calc. for C52.25H60.5B Cl P Pd :
18 2.50 4 2
2
2
C, 47.96; H, 4.66; Found: C, 47.82; H, 4.71%.
2
.2.2. Preparation of [Pd{7,8-(PPh ) -7,8-C B H } ] Æ
2 2 2 9 10 2
2
4
CHCl (2)
3
squares calculations on F . All the H atoms were located
PdCl (18.8 mg, 0.10 mmol) was added to a solution of
in a difference Fourier map and thereafter refined isotrop-
ically, except the bridge H atoms of the nido carborane
skeleton. These bridge H atoms were refined isotropically
with fixed U values. Details of the crystal parameters, data
collection and refinement are summarized in Table 1.
2
1
,2-(PPh ) -1,2-C B H (102.4 mg, 0.20 mmol) in 10 ml
2
2
2 10 10
cyanophenyl and stirred for 10 h under the protection of
dry N . The yellow solid that formed was filtered off, and
2
dried in vacuum (42.7 mg, 38.5%). M.p. 236–237 ꢁC. A
crystal for X-ray diffraction was grown from a chloroform
ꢀ
1
solution layered with ether. FT-IR m
(cm ): 3042 m,
3. Results and discussion
KBr
1
2
560 m, 1423 m, 1108 m, 735 m. H NMR (400.15 MHz,
1
3
CDCl ): ꢀ2.13 ppm (2H, B–H–B); C NMR (100.63
3.1. Synthesis
3
MHz, CDCl ): 125–132 ppm (48C), 77.1 ppm (4C). Anal.
3
Calc. for C H B Cl P Pd: C, 42.37; H, 4.06; Found:
The metal driven degradation of the closo carborane
5
6
64 18 12 4
C, 42.30; H, 4.00%.
diphosphine 1,2-(PPh ) -1,2-C B H with C–P retention
2
2
2 10 10

J.-M. Dou et al. / Polyhedron 26 (2007) 719–724
721
Table 1
Details of the crystal parameters, data collection and refinement for complexes 1, 2, 3 and 4
Crystal data
1
2
3
4
Empirical formula
Formula weight
Temperature (K)
C
52.25
H
60.5
B18Cl2.50
P
4
Pd
2
C
56
H
64
B
18Cl12
P
4
Pd
C
689.84
298(2)
26
H
30
B
10Cl
2
P
2
Pd
C
872.74
298(2)
26 30 10 2 2
H B I P Pd
1308.39
298(2)
0.71073
1587.33
298(2)
0.71073
˚
Wavelength (A)
0.71073
0.71073
Crystal system
Space group
a (A)
monoclinic
C2/c
28.384(12)
16.575(7)
21.392(9)
90
128.635(5)
90
7862(6)
4
monoclinic
P2(1)/c
22.321(9)
16.465(6)
19.922(8)
90
94.096(7)
90
7303(5)
4
triclinic
monoclinic
P2(1)/n
12.003(3)
18.202(4)
14.631(3)
90
95.759(4)
90
3180.4
4
ꢀ
P1
˚
8.4846(15)
11.0660(19)
17.148(3)
89.031(2)
85.447(2)
75.456(2)
1553.5(5)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
˚
3
V (A )
Z
ꢀ1
Absorption coefficient (mm
)
0.652
1.105
2634
0.818
1.444
3200
0.891
1.475
692
2.644
1.823
1672
ꢀ3
D (Mg m
F(000)
)
Crystal size (mm)
Theta range (ꢁ)
Limiting indices
0.39 · 0.38 · 0.34
2.29–25.01
0.35 · 0.33 · 0.31
1.81–25.01
ꢀ26 6 h 6 24
ꢀ16 6 k 6 19
ꢀ22 6 l 6 23
12664
0.48 · 0.33 · 0.21
1.90–25.01
ꢀ7 6 h 6 10
ꢀ13 6 k 6 12
ꢀ19 6 l 6 20
5400
0.33 · 0.31 · 0.29
2.09–25.01
ꢀ14 6 h 6 13
ꢀ21 6 k 6 17
ꢀ12 6 l 6 17
5558
ꢀ31 6 h 6 33
ꢀ
19 6 k 6 19
25 6 l 6 19
ꢀ
Independent reflection
6643
Max. and min. transmission
Goodness-of-fit on F
0.8088 and 0.7851
1.006
0.7855 and 0.7627
1.017
0.8350 and 0.6744
1.005
0.5144 and 0.4757
1.000
2
R[I > 2r(I)]
R
1
= 0.0707
wR = 0.1591
= 0.2072
wR = 0.2128
1.125 and ꢀ0.609
R
1
= 0.0707
wR = 0.1726
= 0.1543
wR = 0.2372
1.106 and ꢀ0.850
R
1
= 0.0362
wR = 0.0861
= 0.0529
wR = 0.0978
0.545 and ꢀ0.311
R
1
= 0.0416
wR = 0.1186
= 0.0500
wR = 0.1265
1.162 and ꢀ1.320
2
2
2
2
R (all data)
R
1
R
1
R
1
R
1
2
2
2
2
2
˚
ꢀ3
)
Largest difference in peak and hole (·10 e A
was first disclosed by Teixidor’s group in 1993 [4]. Based on
the result, much research work has been done relevant to
this area by this group [10–13], and many complexes con-
ratio was changed to 1:2 with the conditions otherwise the
same, the same product was obtained, indicating that the
ratio of the reactants has no influence on the result of this
reaction. However, when the reaction was carried out with
the starting material PdCl and 1,2-(PPh ) -1,2-C B H
2 10 10
ꢀ
taining the nido-[7,8-(PPh ) -7,8-C B H ] anion, such as
2
2
2
9
10
Ru [14], Rh [15], Au [16,17], Ag [18] and Ni, Pd and Pt
8], have been reported. By treatment of PdCl with the closo
2
2 2
[
with a molar ratio 1:2 in cyanophenyl, the complex
2
diphosphine ligand 1,2-(PPh ) -1,2-C B H in a molar
[Pd{7,8-(PPh ) -7,8-C B H } ] Æ 4CHCl (2) was obtained,
2
2
2
10 10
2 2
2
9
10 2
3
ratio 1:1 in acetonitrile under refluxing conditions, we
obtained a binuclear Pd complex with the formula [Pd2-
in which the two Cl ions of the initial PdCl were substituted
2
by the nido carborane diphosphine anion [7,8-(PPh ) -7,8-
2 2
ꢀ
(
l-Cl) {7,8-(PPh ) -7,8-C B H } ] Æ 0.25CH Cl (1), in
C B H ] . The reactions are shown in Scheme 1. From
2
2 2
2
9
10 2
2
2
2
9
10
which the closo structure of the carborane skeleton was also
these results, it seemed that the solvent could play an impor-
tant role in the formation process of the complexes.
degraded. When the PdCl :carborane diphosphine ligand
2
Ph2
H
PPh2
P
C
acetonitrile
reflux
C
Pd
Cl
C
C
PdCl2
PPh2
P
Ph
2
Ph
2
Ph2
P
H
H
PPh2
P
C
cyanophenyl
stir
C
C
Pd
C
PdCl2
C
2
C
PPh2
P
Ph
P
2
Ph
2
Scheme 1. The reactions for the preparation of complexes 1 and 2.

722
J.-M. Dou et al. / Polyhedron 26 (2007) 719–724
In strong nucleophilic solvents, such as ethanol [8],
acetonitrile and cyanophenyl, the closo carborane skeleton
could be degraded in the reactions of Pd compounds with
the closo ligand. However, in mild nucleophilic solvents,
for example dichloromethane, the closo structure of the car-
borane could be preserved [6,7]. The complex [PdCl (1,2-
2
(
PPh ) -1,2-C B H )] Æ CH Cl could be obtained by the
2 2 2 10 10 2 2
reactions of the closo ligand with [PdCl (cod)] in CH Cl
2
2
2
or [PdCl (PhCN) ] in toluene [5]. Here, we revised the
2
2
method for the preparation of this complex. By using
PdCl as the initial material to react with the closo ligand
2
in dichloromethane under refluxing conditions, we also
obtained this complex. This result further confirmed the
conclusion that a mild nucleophilic solvent could avoid
the degradation of the closo diphosphine ligand. The corre-
sponding PdI2 complex [PdI (1,2-(PPh ) -1,2-C B H )]
2
2 2
2
10 10
ꢀ
Fig. 1. Perspective view of complex unit of 1. The H atoms are omitted for
clarity.
(
4) was obtained through the substitution of Cl in
ꢀ
[
PdCl (1,2-(PPh ) -1,2-C B H )] with I under refluxing
2
2 2
2 10 10
conditions in CH Cl after several hours. The bromide
2
2
derivative could also be afforded by this type of ligand
exchange reaction, although the process was more difficult
than that for the preparation of complex 4 (refluxing for 8
days) [7].
3
.2. Spectral characterization
1
All the complexes were characterized by FT-IR, H and
C NMR spectroscopy. The IR spectra of these complexes
1
3
were very similar to each other and exhibited absorptions
characteristic of terminal B–H vibrations at about 2540–
ꢀ
1
2
600 cm in the four complexes, which are in the normal
ꢀ1
range for B–H vibrations of 2625–2450 cm
absorptions at 3052, 3042, 3000 and 3030 cm might be
[19]. The
ꢀ
1
attributed to the mC–H stretching vibration of the benzene
ꢀ1
rings. Several peaks were found from 1695 to 1410 cm
,
which might be assigned to m stretching vibrations.
C@C
ꢀ1
The peak at ca. 1400 cm was the in-plane deformation
mode of the benzene ring, and the peak at ca. 1100 cm
ꢀ
1
Fig. 2. Perspective view of complex unit of 2. The H atoms are omitted for
clarity.
was the absorption of mC(phenyl)–P, which was a little shifted
in keeping with phosphorus coordination to the carborane
ꢀ
1
moiety. The absorption at approximately 740 cm showed
the unit cell and the disordered solvent CH Cl . The molec-
2
2
1
the existence of cage deformation. The H NMR spectra
400.15 MHz) of these complexes displayed a complex pat-
tern of resonances at about 7.1–7.6 ppm which could be
attributed to the phenyl-H of the PPh groups. A resonance
ular structure of complex1 is symmetrical and the symme-
try transformations used to generate equivalent atoms are
ꢀx + 1/2, ꢀy + 3/2, ꢀz + 2. Two Cl atoms bridge the
two same Pd[7,8-(PPh ) -7,8-C B H ] units. The dihedral
(
2
2 2
2
9
10
at ca. ꢀ2.1 ppm is the bridge H atom of B–H–B [4]. In the
angel between central plane formed by the [Pd Cl ] unit
2 2
1
3
C NMR spectra (100.63 MHz), a resonance at ca.
and the side P(1)Pd(1)P(2) plane is only 3.3ꢁ, indicating
d = 130 ppm could be assigned to the benzene ring C
atoms, and a resonance at ca. d = 77 could be assigned
to the carbon atom of carborane cage (Cc) [20].
that these two planes are almost parallel to each other.
˚
The Pd–Cl distance, 2.394(3) A, is almost equal to the bond
i
˚
length of 2.405(5) A in [Pd (l-Cl) {7,8-(P Pr ) -7,
2
2
2 2
8
-C B H } ] [12], but slightly longer than the average
2 9 10 2
˚
distance of 2.338(2) A in [PdCl(PPh ){7,8-(PPh ) -7,8-
3 2 2
3
.3. Crystallographic data of the complexes
C B H }] Æ 1.25 CH Cl [8]. The two Pd–P bonds
2
9
10
2
2
˚
Crystal structures of the four complexes are shown in
(2.233(2) and 2.236(2) A) and the P–Pd–P angle
Figs. 1–4, respectively. Selected bond lengths and angles
are given in Table 2. Complex 1 crystallizes in the mono-
clinic space group C2/c, containing four formula units in
(85.23(8)ꢁ) are all consistent with the average values
i
˚
2.238 A and 87.0(1)ꢁ in [Pd (l-Cl) {7,8-(P Pr ) -7,8-
2
2
2 2
˚
C B H } ]. The average distances of P–Cc, 1.817 A, and
2
9
10 2

J.-M. Dou et al. / Polyhedron 26 (2007) 719–724
723
Fig. 3. The crystal structure of complex 3. The H atoms are omitted for
clarity.
Fig. 4. The crystal structure of complex 4. The H atoms are omitted for
clarity.
˚
Cc–Cc, 1.556(13) A, are slightly shorter than the corre-
˚
sponding distances, 1.87 and 1.61(2) A, in [NMe ]-
4
[
7,8-(PPh ) -7,8-C B H ] Æ CH CH OH [10], implying that
ate much from the values for a regular square-planar coor-
dination mode. The distances of the four Pd–P bonds are
almost equal to each other, and the average value of
2
2
2
9
10
3
2
coordination of the ligand to the Pd atom has an influence
on these bond lengths.
˚
Complex 2 also contains four formula units in the unit
2.362 A is obviously longer than those in complex 1, which
cell and the solvent CHCl , and crystallizes in the mono-
can be attributed to the steric effect of the two ligands. The
angles of P(1)–Pd(1)–P(2), 82.63(7)ꢁ, and P(3)–Pd(1)–P(4),
82.86(7)ꢁ, are slightly smaller than the value of 85.23(8)ꢁ in
3
clinic space group P2(1)/c. The central Pd atom is coordi-
nated to four P atoms coming from two nido carborane
ꢀ
i
diphosphine anions [7,8-(PPh ) -7,8-C B H ] . The geom-
[Pd (l-Cl) {7,8-(P Pr ) -7,8-C B H } ]. As for the other
2
2
2
9
10
2
2
2 2
2
9
10 2
etry at the Pd atom is seriously distorted square-planar
with a mean deviation from the P(1)P(2)P(3)P(4)Pd(1)
plane of 0.3141 A, and the angles around Pd (Table 2) devi-
parameters in complex 2, such as the distances of P–Cc
and Cc–Cc as listed in Table 2, no noticeable differences
have been found on comparison to those in complex 1.
˚
Table 2
˚
Selected bond lengths (A) and angles (ꢁ) for complexes 1, 2, 3 and 4
1
2
3 (X@Cl)
4 (X@I)
Pd(1)–P(1)
Pd(1)–P(2)
Pd(1)–Cl(1)
Pd(1)–Cl(1)#1
P(1)–C(7)
2.233(2)
2.236(2)
2.394(3)
2.395(2)
1.814(9)
1.819(9)
1.556(13)
85.23(8)
94.16(8)
85.18(8)
95.33(8)
177.3(11)
177.8(11)
111.3(3)
110.9(3)
114.2(6)
113.5(5)
Pd(1)–P(1)
Pd(1)–P(2)
Pd(1)–P(3)
Pd(1)–P(4)
P(1)–C(7)
P(2)–C(8)
2.359(2)
2.362(2)
2.359(2)
2.368(2)
1.824(8)
1.833(8)
1.817(8)
1.832(8)
1.556(11)
160.55(7)
103.93(7)
82.63(7)
82.86(7)
96.99(7)
160.52(7)
116.2(5)
114.2(5)
Pd(1)–P(1)
Pd(1)–P(2)
Pd(1)–X(1)
Pd(1)–X(2)
P(1)–C(1)
P(2)–C(2)
C(1)–C(2)
P(2)–Pd(1)–P(1)
P(2)–Pd(1)–X(2)
P(1)–Pd(1)–X(2)
P(2)–Pd(1)–X(1)
P(1)–Pd(1)–X(1)
X(2)–Pd(1)–X(1)
C(1)–P(1)–Pd(1)
C(2)–P(2)–Pd(1)
C(2)–C(1)–P(1)
C(1)–C(2)–P(2)
2.239(1)
2.239(1)
2.333(1)
2.330(1)
1.873(4)
1.883(3)
1.677(5)
89.73(4)
174.09(4)
88.44(4)
89.77(4)
178.75(4)
91.94(4)
108.0(10)
108.1(11)
113.1(2)
113.3(2)
2.262(14)
2.262(14)
2.622(7)
2.614(7)
1.883(5)
1.885(5)
1.687(7)
91.37(5)
175.39(4)
87.77(4)
88.88(4)
176.97(4)
91.74(2)
108.1(2)
107.6(2)
113.8(3)
114.8(3)
P(2)–C(8)
C(7)–C(8)
0
P(3)–C(7 )
0
P(1)–Pd(1)–P(2)
P(1)–Pd(1)–Cl(1)
Cl(1)–Pd(1)–Cl(1)#1
P(2)–Pd(1)–Cl(1)#1
P(2)–Pd(1)–Cl(1)
P(1)–Pd(1)–Cl(1)#1
C(7)–P(1)–Pd(1)
C(8)–P(2)–Pd(1)
C(7)–C(8)–P(2)
C(8)–C(7)–P(1)
P(4)–C(8 )
C(7)–C(8)
P(1)–Pd(1)–P(4)
P(1)–Pd(1)–P(3)
P(1)–Pd(1)–P(2)
P(3)–Pd(1)–P(4)
P(2)–Pd(1)–P(4)
P(3)–Pd(1)–P(2)
C(7)–C(8)–P(2)
C(8)–C(7)–P(1)
Symmetry transformations used to generate equivalent atoms for complex 1: ꢀx + 1/2, ꢀy + 3/2, ꢀz + 2.

724
J.-M. Dou et al. / Polyhedron 26 (2007) 719–724
As for complex 4, the Pd atom is also four coordinate, in
which two positions are occupied by the closo carborane
and Open Research Fund Program of Key Laboratory of
Marine Drugs (Ocean University of China).
diphosphine 1,2-(PPh ) -1,2-C B H , and the other two
2
2
2 10 10
come from two I atoms in cis positions, fulfilling the
slightly distorted square-planar coordination. The mean
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. Conclusions
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,2-(PPh ) -1,2-C B H with PdCl in different solvents
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5
. Supplementary material
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Acknowledgements
This work was supported by the National Natural Sci-
ence Foundation of P. R. China (project no. 20371025)