1-Selenolato-2-phenyl-o-carborane complexes of palladium(II) and platinum(II): Synthesis, spectroscopy and structures

Article abstract of DOI:10.1016/j.jorganchem.2010.08.022

The reactions of PhCb^oSeNa (Cb^o = o-C ₂B₁₀H₁₀), prepared by reductive cleavage of Se-Se bond in (PhCb^oSe)₂ by NaBH₄ in methanol, with Na₂PdCl₄, MCl₂(PR₃)₂ and [M₂Cl₂(μ-Cl)₂(PR₃) ₂] afforded a variety of complexes, viz., [Pd(SeCb^oPh)Cl] (1), [M(SeCb^oPh)₂(PR₃)₂], [M ₂Cl₂(μ-SeCb^oPh)(μ-Cl)(PR ₃)₂] (M = Pd, Pt) and [Pd₂Cl(SeCb ⁰Ph)(μ-Cl)(μ-SeCb^oPh)(PEt₃)₂] (7) have been isolated. These complexes were characterized by elemental analyses and NMR (¹H, ³¹P, ⁷⁷Se, ¹⁹⁵Pt) spectroscopy. The structures of [Pd(SeCb^oPh)₂(PEt ₃)₂] (2), [Pt(SeCb^oPh)₂(PMe ₂Ph)₂] (3), [Pd₂Cl₂(μ-SeCb ^oPh)(μ-Cl)(PMe₂Ph)₂] (5) and [Pd ₂Cl(SeCb^oPh)(μ-Cl)(μ-SeCb^oPh)(PEt ₃)₂] (7) were established by X-ray crystallography. The latter represents the first example of asymmetric coordination of selenolate ligands in binuclear bis chalcogenolate complexes of palladium and platinum. Thermolysis of [Pd(SeCb^oPh)₂(PEt₃)₂] (2) in HDA (hexadecylamine) at 330 °C gave nano-crystals of Pd ₁₇Se₁₅.

Full text of DOI:10.1016/j.jorganchem.2010.08.022

Journal of Organometallic Chemistry 695 (2010) 2629e2634
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
1-Selenolato-2-phenyl-o-carborane complexes of palladium(II) and platinum(II):
Synthesis, spectroscopy and structures
,
a
a
b
Manoj K. Pal a, Vimal K. Jain a , Nisha P. Kushwah , Amey Wadawale , Sergey A. Glazun ,
*
Zoya A. Starikova b, Vladimir I. Bregadze b
,
**
a Chemistry Divison, Bhabha Atomic Research Center, Mumbai 400085, India
b A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov Str. 119991 Moscow, Russia
a r t i c l e i n f o
a b s t r a c t
The reactions of PhCboSeNa (Cbo ¼ o-C2B10H10), prepared by reductive cleavage of SeeSe bond in
Article history:
(PhCboSe)2 by NaBH4 in methanol, with Na2PdCl4, MCl2(PR3)2 and [M2Cl2(
m-Cl)2(PR3)2] afforded a variety
Received 29 April 2010
Received in revised form
9 August 2010
Accepted 13 August 2010
Available online 23 September 2010
of complexes, viz., [Pd(SeCboPh)Cl] (1), [M(SeCboPh)2(PR3)2], [M2Cl2(
and [Pd2Cl(SeCb0Ph)( -SeCboPh)(PEt3)2] (7) have been isolated. These complexes were character-
-Cl)(
ized by elemental analyses and NMR (1H, 31P, 77Se, 195Pt) spectroscopy. The structures of [Pd(SeC-
boPh)2(PEt3)2] (2), [Pt(SeCboPh)2(PMe2Ph)2] (3), [Pd2Cl2( -SeCboPh)(
-Cl)(PMe2Ph)2] (5) and [Pd2Cl
(SeCboPh)( -SeCboPh)(PEt3)2] (7) were established by X-ray crystallography. The latter represents
-Cl)(
m
-SeCboPh)(
m
-Cl)(PR3)2] (M ¼ Pd, Pt)
m
m
m
m
m
m
Keywords:
Seleno-o-carborane
Palladium
the first example of asymmetric coordination of selenolate ligands in binuclear bis chalcogenolate
complexes of palladium and platinum. Thermolysis of [Pd(SeCboPh)2(PEt3)2] (2) in HDA (hexadecyl-
amine) at 330 ꢀC gave nano-crystals of Pd17Se15
.
Platinum
Ó 2010 Elsevier B.V. All rights reserved.
Complexes
X-ray structures
1. Introduction
synthesis of palladium selenides by cleavage of CeSe bond.
Accordingly, reactions of 2-phenyl-o-carboraneselenolate with
palladium and platinum compounds have been examined. The
results of this work are reported herein.
Platinum group metal organochalcogenolates are attractive not
only because of their rich reaction chemistry and structural diver-
sity [1e3], but also due to their applications as catalysts in organic
transformations [4e7], enzymatic models in biological systems, in
cancer chemotherapy [8,9] and more recently as molecular
precursors for metal chalcogenides, MxEy (M ¼ Pd or Pt; E ¼ S, Se,
and Te) [10e12]. Several of these chalcogenides show semi-
conducting properties and find numerous applications in electronic
industry and catalysis [10]. Recently we have described the
synthesis of mononuclear palladium and platinum complexes
derived from 2-mercapto carboranes [13]. The three dimensional
steric demand of carborane has led to subtle differences in the
reactivity of these complexes when compared with those con-
taining simple thiolate ligands. In the above perspective and in
pursuance of our interest in palladium/platinum complexes, it was
considered worthwhile to explore the chemistry of heavier chal-
cogen containing carboranes with the following objectives (i) to
identify structural motifs generated by these ligands and (ii) facile
2. Experimental
Thecompounds, bis(2-phenyl-o-carborane)diselenide, (PhCboSe)2
[14,15], [MCl2(PR3)2] and [M2(m-Cl)2Cl2(PR3)2] [16] were prepared
according to literature methods. All reactions were carried out in
anhydrous conditions under a nitrogen atmosphere. Melting points
were determined in capillary tubes and are uncorrected. Elemental
analyses were carried outon a FlashEA-1112 CHNSinstrument.1H, 31
P
{1H}, 77Se{1H} and 195Pt{1H} NMR spectra were recorded on a Bruker
Avance-II 300 MHz spectrometer operating at 300, 121.5, 57.24 and
64.29 MHz, respectively. Chemical shifts are relative to internal
chloroform peak (7.26 ppm) for 1H and external 85% H3PO4 (for 31P),
Me2Se (Ph2Se2 in CDCl3, 463 ppm relative to Me2Se for 77Se) and
Na2PtCl6 in D2O (for 195Pt). Mass spectra were measured on a Kratos
MS 890 mass spectrometer. X-ray powder diffractometer data were
collectedona PhillipsX-raydiffractometer(ModelPW1729)usingCu-
ꢀ
Ka
(l
¼ 1.5406 A) radiation. SEM (scanning electron microscopy) and
* Corresponding author.
EDX (energy dispersive X-ray analysis) measurements were made on
a Tesca Vega 2300T/40 instrument.
** Corresponding author. Tel.: þ7 (0) 95 1357 405; fax: þ7 (0) 951 355 085.
E-mail addresses: janvk@barc.gov.in (V.K. Jain), bre@ineos.ac.ru (V.I. Bregadze).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.08.022

2630
M.K. Pal et al. / Journal of Organometallic Chemistry 695 (2010) 2629e2634
Table 1
Crystallographic and structure refinement data for [Pd (SeCboPh)2(PEt3)2] (2), [Pt(SeCboPh)2(PMe2Ph)2] (3), [Pd2Cl2(
m
-Cl)(
m m-Cl)
-SeCboPh)(PMe2Ph)2] (5) and [Pd2Cl(SeCboPh)(
(m
-SeCboPh)(PEt3)2] (7).
[Pd (SeCboPh)2(PEt3)2]
(2)
[Pt
[Pd2Cl2
(
m
-SeCboPh) (
m
-Cl)
[Pd2Cl(SeCboPh)( -SeCboPh)
m-Cl)(m
(PEt3)2] (7)
(SeCboPh)2(PMe2Ph)2] (PMe2Ph)2] (5)
(3)
Chemical Formula
C28H60B20P2PdSe2.2CHCl3 C32H52B20P2PtSe2
C24H37B10Cl3
C28H60B20Cl2Pd2P2Se2.CH2Cl2
P2Pd2Se.0.25CH2Cl2.0.5CH4O
M
T/K
1177.96
100 (2)
1067.89
298 (2)
930.94
100 (2)
1201.45
298 (2)
Size/color
Crystal system
Space group
0.5 ꢂ 0.4 ꢂ 0.3/red prism 0.4 ꢂ 0.15 ꢂ 0.15/yellow 0.3 ꢂ 0.2 ꢂ 0.15/colorless plate
0.5 ꢂ 0.4 ꢂ 0.3/red
Monoclinic
P 2 1/n
18.006 (4)
13.859 (6)
22.433 (6)
Triclinic
Triclinic
Triclinic
P ꢁ 1
P ꢁ 1
P ꢁ 1
ꢀ
a/A
13.5794 (8)
13.9325 (8)
15.4689 (8)
75.1030 (10)
67.6280 (10)
75.0970 (10)
2567.2 (2)
2
11.898 (5)
14.387 (6)
14.965 (3)
107.43(3)
103.97 (3)
98.81 (4)
10.3010 (9)
10.9728 (9)
18.9447 (19)
86.614 (2)
76.019 (2)
64.7840 (10)
1877.5 (3)
2
ꢀ
b/A
ꢀ
c/A
ꢀ
ꢀ
a
/
b
/
110.47 (2)
ꢀ
g
/
3
ꢀ
V/A
2300.3 (16)
2
5245 (3)
4
1.522
Z
dcalc/g cmꢁ3
Diffractometer
1.542
1.542
1.647
Bruker APEX 2
2.180/1176
1.45 to 28.00
ꢁ17 ꢃ h ꢃ 17
ꢁ18 ꢃ k ꢃ 18
ꢁ20 ꢃ l ꢃ 20
SADABS
Rigaku AFC7S
4.727/1040
2.55 to 27.50
ꢁ15 ꢃ h ꢃ 8
ꢁ18 ꢃ k ꢃ 18
ꢁ18 ꢃ l ꢃ 19
Psi-Scan
Bruker APEX 2
2.281/915
4.00 to 27.00
ꢁ13 ꢃ h ꢃ 13
ꢁ14 ꢃ k ꢃ 13
ꢁ24 ꢃ l ꢃ 24
SADABS
Rigaku AFC7S
2.363/2376
2.51 to 27.51
ꢁ21 ꢃ h ꢃ 23
ꢁ10 ꢃ k ꢃ 18
ꢁ29 ꢃ l ꢃ 16
Psi-Scan
0.5375 and 0.3846
12022
4660
m
(mmꢁ1)/F(000)
for data collection/ꢀ
q
Limiting indices
Absorption correction
Tmax and Tmin
No. of unique reflns/
No. of obsd reflns with I > 2
Data/restraints/parameters
0.521 and 0.356
12373
0.5374 and 0.2536
10574
0.705 and 0.581
8085
s(I)
10768
8431
5628
12373/0/649
0.0227/0.0535
10574/0/586
0.0330/0.0663
8085/1/411
0.0394/0.0829
12022/0/532
0.0555/0.1077
Final R1,
wR_factor_gt)
R1, R2 (all data) (R_factor_all/
wR_Factor_ref)
GOF
uR2 indices (R_factor_gt/
u
0.0291/0.0561
0.990
0.0549/0.0730
0.0709/0.0909
0.2112/0.1450
0.991
1.018
0.963
0.694 and ꢁ0.811
ꢀꢁ3
Largerst difference peak and hole (e A ) 1.037 and ꢁ0.732
0.924 and ꢁ1.436
2.158 and ꢁ1.043
2.1. Preparation of [Pd(SeCboPh)Cl]n (1)
To methanolic solution (15 ml) of Na2PdCl4, (59 mg,
7.36e7.44 (m); 7.71 (d, 7.0 Hz). 31P{1H} NMR (CDCl3)
77Se{1H} NMR (CDCl3)
: 257 ppm.
d: 0.5 ppm;
d
a
0.20 mmol), a methanolic solution of NaSeCboPh (prepared from
reduction of (PhCboSe)2 (119 mg 0.20 mmol) in 5 ml benzene by
methanolic solution of NaBH4 (15 mg, 0.40 mmol)) was added with
vigorous stirring which continued for 4 h. The solvent was evapo-
rated under vacuum and the residue was extracted with dichloro-
methane and filtered. The filtrate was concentrated under vacuum
and kept for recrystallization to give dark brown crystals (62 mg,
70% yield), m.p. 130 ꢀC. Anal. Calcd. for C8H15B10ClPdSe: C, 21.8; H,
3.4%. Found: C, 22.0; H, 3.8%. Mass spectrum (m/e): 519.4 (Pd
(SeCboPh)(Cl)Se); 439.4 (PdCl(SeCboPh)); 235.4; 219.5 (CboPh). 1H
2.3. Preparation of [Pt(SeCboPh)2(PMe2Ph)2] (3)
Prepared similar to 2 as a yellow crystalline solid in 73% yield,
m.p. 170 ꢀC. Anal. Calcd. for C32H52B20P2PtSe2: C, 36.0; H, 4.9%.
Found: C, 35.9; H, 4.9%. 1H NMR (CDCl3)
d: 1.50 (d, 10 Hz); 1.75 (d,
13 Hz); 2.20 (d, 13 Hz, PMe2); 7.14e7.72 (m, Ph). 31P{1H} NMR
(CDCl3)
289 ppm.
d
: ꢁ19.5 (1J(PteP) ¼ 3022 Hz). 77Se{1H} NMR (CDCl3)
d:
2.4. Preparation of [Pt(SeCboPh)2(PMePh2)2] (4)
NMR (dmso-d6)
NMR (dmso-d6)
d
: 7.32e7.40 (m); 7.51 (d, 7.7 Hz); 7.66 (m). 77Se{1H}
: 839 ppm.
d
Prepared similar to 2 as a yellow crystalline solid in 74% yield,
m.p. 185 ꢀC. Anal. Calcd. for C42H56B20P2PtSe2: C, 42.3; H, 4.7%.
Found C, 42.6; H, 4.7%. 1H NMR (CDCl3)
d
: 1.91 (d, J(PeH) ¼ 10 Hz; J
2.2. Preparation of [Pd(SeCboPh)2(PEt3)2] (2)
(PteH) ¼ 32 Hz); 7.22e7.45 (m); 7.60 (d, 7 Hz). 31P{1H} NMR (CDCl3)
d
: ꢁ7.8 (1J(PteP) ¼ 3054 Hz). 77Se{1H} NMR (CDCl3)
d: 320 ppm.
To a dichloromethane solution (15 ml) of [PdCl2(PEt3)2] (83 mg,
0.20 mmol), a methanolic solution of NaSeCboPh (prepared from
reduction of (PhCboSe)2 (119 mg 0.20 mmol) in 5 ml benzene by
methanolic solution of NaBH4 (15 mg, 0.40 mmol)) was added with
vigorous stirring which continued for 4 h. The solvent was evapo-
rated under vacuum and the residue was extracted with dichloro-
methane and then filtered. The filtrate was concentrated under
vacuum and the residue was recrystallized from chloroform as a red
crystalline solid (113 mg, 60% yield); m.p. 133 ꢀC. Anal. Calcd. for
C28H60B20P2PdSe2.2CHCl3: C, 30.5; H, 5.3%. Found: C, 30.6; H, 5.3%.
2.5. Preparation of [Pd2Cl2(
m
-SeCboPh)(
m-Cl)(PMe2Ph)2] (5)
To a dichloromethane solution (20 ml) of [Pd2Cl2(
m
-Cl)2(PMe2
Ph)2] (126 mg, 0.2 mmol), a methanolic solution of NaSeCboPh
(prepared from (PhCboSe)2 (119 mg 0.20 mmol) and NaBH4 (15 mg,
0.40 mmol) in methanol) was added and the reaction mixture was
stirred at room temperature for 4 h. The solvents were evaporated
under a reduced pressure and the residue was extracted with
dichloromethane which on concentration to 10 ml and on cooling
1H NMR (CDCl3)
d: 0.83e0.91 (m, PCH2Me); 1.72e1.78 (m, PCH2);

M.K. Pal et al. / Journal of Organometallic Chemistry 695 (2010) 2629e2634
2631
Ph
Ph
PEt3
Se
Se
R3P
Se Pd
Se
Pt
R3P
PEt3
(2)
Ph
PdCl2(PEt3)2
Ph
PtCl2(PR3)2
PR3=PMe2Ph (3)
PMePh2 (4)
SeNa
Se
Se
Ph
Ph
Ph
NaBH4
2
2 [M2Cl2(μ-Cl)2(PR3)2]
[Pd2Cl2(μ-Cl)2(PEt3)2]
Cl
Cl
Cl
Et3P
Cl
Cl
M
M
Pd
Pd
Ph
R3P
Se
PR3
Se
Ph
Se
PEt3
Ph
M
PR3
= C
= BH
Pd PMe2Ph (5)
Pt
PEt3 (6)
(7)
Scheme 1.
afforded yellow crystals (98 mg, 55% yield), m.p. 200 ꢀC (dec.). Anal.
Calcd. for C24H37B10Cl3P2Pd2Se. CH2Cl2: C, 30.7; H, 4.0%. Found: C,
1.5 h. This was cooled to 70 ꢀC and methanol was added. The
contents were centrifuged leaving a black residue, which was
washed with methanol (15 ml ꢂ 3) and dried in vacuo.
31.0; H, 3.9%. 1H NMR (dmso-d6)
d
: 1.69,1.82 (each d,12.5 Hz, PMe2);
7.45e7.65(m, Ph), 7.86e7.91 (m). 31P{1H}NMR (dmso-d6)
:10.8,14.2
(each s). 77Se{1H} NMR (dmso-d6)
: 452 (s) ppm.
d
d
2.9. Crystallographic experiment
2.6. Preparation of [Pt2Cl2(m m-Cl)(PEt3)2] (6)
-SeCboPh)(
Single-crystal X-ray diffraction measurements were made on
a Bruker APEX-2 diffractometer for 2 and 5 and Rigaku AFC 7S
Prepared similar to 5 in 74% yield, m.p. 165 ꢀC. Anal. Calcd. for
diffractometer for 3 and 7 using graphite monochromated Mo-K
a
C20H45B10 Cl3P2Pt2Se: C, 23.3; H, 4.4%. Found: C, 23.7; H, 4.3%. 1H
ꢀ
(l
¼ 0.71069 A) radiation. Low temperature diffraction data were
NMR (CDCl3)
d: 1.06e1.18 (m, PCH2CH3); 1.77e1.84 (m, PCH2);
collected by keeping the crystal at low temperature using a cryo-
stream (Oxford Cryo-Systems) open-flow N2 gas cryostat. The
structures were solved by direct methods [17] and refinement was
on F2 [17] using data that had been corrected for Lorentz and
polarization effects with an empirical procedure [18]. The non-
hydrogen atoms were refined anisotropically. The experimental
data had been corrected for absorption effects with sadabs (for 2
and 5) [19]and psi-scans (for 3 and 7) procedures [20], the car-
borane hydrogen atoms were located from the difference Fourier
syntheses, the H(C) atoms were placed in geometrically calculated
positions. All hydrogen atom positions were refined in isotropic
approximation in riding model with the Uiso(H) parameters equal
to nUeq(Ci), where Ueq(Ci) are the equivalent thermal parameters
of the atoms to which corresponding H atoms are bonded, n ¼ 1.2
for CHe and CH2-groups, n ¼ 1.5 for CH3-groups. Molecular
structures were drawn using ORTEP [21]. Crystallographic data,
together with data collection and refinement details are given in
Table 1.
7.27e7.70 (m, Ph). 31P{1H} NMR (CDCl3)
d
: 9.1 (1J(PteP) ¼ 3836 Hz).
77Se{1H} NMR (CDCl3)
d
: 244 (1J(PteSe) ¼ 118 Hz). 195Pt{1H} NMR
(CDCl3)
d
: ꢁ3894 (d, 1J(PteP) ¼ 3812 Hz).
Preparation of [Pd2Cl(SeCb0Ph)( -SeCboPh)(PEt3)2] (7)
m-Cl)(m
Prepared by a method similar to 5 by using [Pd2Cl2(m-Cl)2(PEt3)2]
and NaSeCboPh in 1:2 M ratio. Yield 65%, m.p. 210 ꢀC. Anal. Calcd. for
C28H60B20 Cl2P2Pd2Se2: C, 30.1; H, 5.4%. Found: C, 30.7; H, 5.4%. 1H
NMR (CDCl3) d: 1.02e1.26 (m, PCH2CH3); 1.62e1.85 (m, PCH2);
7.42e7.77 (m, Ph). 31P{1H} NMR (CDCl3) : 27.2, 42.4 (each s). 77Se
d
{1H} NMR(CDCl3)
d
: 352 (s); 157 (d, J(77See31P) ¼ 152 Hz).
2.8. Thermolysis of [Pd(SeCboPh)2(PEt3)2]
In a typical experiment 2 (70 mg) and HDA (hexadecylamine)
(2.5 g) were taken in a round bottom flask and heated at 330 ꢀC for

2632
M.K. Pal et al. / Journal of Organometallic Chemistry 695 (2010) 2629e2634
Fig. 3. ORTEP drawing of [Pd2Cl2(m-Cl)(m
-SeCboPh)(PMe2Ph)2] (5) with atomic
numbering scheme (ellipsoids drawn with 25% probability).
Fig. 1. ORTEP drawing of [Pd(SeCboPh)2(PEt3)2] (2) with atomic numbering scheme
(ellipsoids drawn with 25% probability).
suggestive of coupling with one 31P nucleus. The magnitude of 1J
(PteP) (w3800 Hz) coupling constant is in conformity with the
sym-cis configuration having phosphine ligands trans to bridging
chloride [1]. The 31P{1H} NMR of 7 showed two resonances which
can be assigned to the phosphine ligands coordinated to two
different palladium atoms. The 77Se{1H} NMR spectra of 1e6 dis-
3. Results and discussion
Treatment of Na2PdCl4 with NaSeCboPh, prepared by reductive
cleavage of SeeSe bond of (PhCboSe)2 by methanolic NaBH4, affords
a dark brown complex of composition, [Pd(SeCboPh)Cl]n (1). The
reactions of MCl2(PR3)2 with two equivalents of NaSeCboPh yield
bis(selenolate) complexes, [M(SeCboPh)2(PR3)2] (M/PR3 ¼ Pd/PEt3
played a single resonance in the region
d 244e839 ppm while the
spectrum of 7 showed two such resonances due to two different
selenolate groups. The mass spectrum of 1 displayed a peak of
highest mass at m/e 519.4 with the isotopic pattern corresponding
to [Pd(SeCboPh)(Cl)Se]. Another peak at m/e 439.4 is assigned for
[PdCl(SeCboPh)] fragment. Several complexes of composition [PdCl
(ER)]n (E ¼ S, Se, Te) have been described in literature. Polymeric
insoluble complexes are formed when R is an aryl (e.g. Ph) or
pyridyl group [23]. However, with internally functionalized alkyl
group, bi and tri-nuclear complexes, [PdCl(SeCH2CH2NMe2)]3 [12]
and [PdCl(ECH2CH2CH2NMe2)]2 (E ¼ S, Se, Te) [24] are formed.
The molecular structures of [Pd(SeCboPh)2(PEt3)2] (2), [Pt(SeC-
(2); Pt/PMe2Ph (3) and Pt/PMePh2 (4)). The reaction of [M2Cl2(m-
Cl)2(PR3)2] with NaSeCboPh in 1:1 M ratio gives complexes of
composition [M2Cl2(m-Cl)(m
-SeCboPh)(PR3)2] (M/PR3 ¼ Pd/PMe2Ph
(5) and Pt/PEt3 (6)) whereas similar reaction (when M ¼ Pd) in 1:2
stoichiometry yields [Pd2Cl(SeCboPh)(
as a red crystalline solid (Scheme 1).
m-Cl)(m
-SeCboPh)(PEt3)2] (7)
The 31P{1H} NMR spectra of 3 and 4 displayed a singlet with 1J
(PteP) of w3000 Hz indicating a cis configuration [22]. The 31P{1H}
NMR spectrum of 6 exhibited a single resonance suggesting the
presence of only one isomeric species. Similarly, in the 195Pt{1H}
NMR spectrum a doublet centered at
d
ꢁ3894 ppm was observed
boPh)2(PMe2Ph)2] (3) [Pd2Cl2(
m-Cl)(m
-SeCboPh)(PMe2Ph)2] (5) and
[Pd2Cl(SeCboPh)( -SeCboPh)(PEt3)2] (7) have been estab-
m-Cl)(
m
lished unambiguously by single crystal X-ray diffraction analyses.
The crystals of 2, 5 and 7 contain solvent of crystallization. The
ORTEP drawings with atomic number scheme are shown in Figs.
1e4 and selected bond lengths and angles are given in Tables
Fig. 2. ORTEP drawing of [Pt(SeCboPh)2(PMe2Ph)2] (3) with atomic numbering scheme
(ellipsoids drawn with 25% probability).
Fig. 4. ORTEP drawing of [Pd2Cl(
numbering scheme (ellipsoids drawn with 25% probability).
m-Cl)(m
-SeCboPh)(SeCboPh)(PEt3)2] (7) with atomic

M.K. Pal et al. / Journal of Organometallic Chemistry 695 (2010) 2629e2634
2633
Table 2
Table 4
o
o
-SeCboPh)
ꢀ
ꢀ
ꢀ
ꢀ
The selected bond lengths (A) and angles ( ) for trans-[Pd(SeCb Ph)2(PEt3)2].2CHCl3
(2) and [Pt(SeCboPh)2(PMe2Ph)2] (3).
The selected bond lengths (A) and angles ( ) for [Pd2Cl(SeCb Ph)(
m
-Cl)(m
(PEt3)2] (7).a
[Pd(SeCboPh)2(PEt3)2]$2CHCl3 (2)a [Pt(SeCboPh)2(PMe2Ph)2] (3)b
Pd1eCl1
Pd1eCl2
Pd1eSe1
Pd1eP1
Se1eC1
C1eC2
C2eC3(Ph)
Pd1ePd2
2.315 (2)
2.428 (2)
2.4139 (10)
2.235 (3)
1.966 (6)
1.717 (9)
1.497 (9)
3.461
Pd2eCl2
Pd2eSe1
Pd2eSe2
Pd2eP2
Se2eC9
C9eC10
2.3835 (19)
2.5278 (11)
2.3996 (11)
2.274 (2)
1.942 (7)
1.745 (9)
M1eSe1
M1eSe2
M1eP1
M1eP2
Se1eC1
2.4945 (2)
2.4794 (2)
2.3495 (4)
2.3508 (4)
1.9240 (16)
1.9242 (16)
1.752 (2)
2.4945 (11)
2.5094 (10)
2.2749 (14)
2.2706 (14)
1.939 (4)
C10eC11(Ph)
1.486 (10)
Se2eC9
C1eC2
1.928 (4)
1.742 (6)
C9eC10
C2eC3(Ph)
C10eC11(Ph)
1.747 (2)
1.505 (2)
1.505 (2)
1.760 (6)
1.508 (6)
1.509 (6)
Pd1eCl2ePd2
Cl1ePd1eSe1
Cl1ePd1eCl2
Cl1ePd1eP1
Cl2ePd1eP1
Cl2ePd1eSe1
Se1ePd1eP1
C1eSe1ePd1
91.97 (7)
174.32 (9)
90.21 (9)
87.16 (10)
177.36 (8)
86.30 (5)
Pd1eSe1ePd2
Cl2ePd2eSe1
Cl2ePd2eSe2
Cl2ePd2eP2
Se1ePd2eP2
Se1ePd2eSe2
P2ePd2eSe2
Pd2eSe1eC1
Pd2eSe2eC9
88.87 (3)
84.74 (6)
173.42 (6)
94.44 (8)
173.35 (6)
91.71 (4)
89.72 (6)
98.76 (19)
103.0 (2)
Se1eM1eSe2 176.850 (7)
Se1eM1eP1 86.931 (12)
Se1eM1eP2 94.620 (12)
Se2eM1eP1 94.178 (12)
Se2eM1eP2 85.931 (12)
P1eM1eP2 160.297 (16)
90.09 (4)
170.64 (3)
83.65 (5)
89.54 (5)
167.66 (3)
98.35 (5)
96.32 (7)
104.21 (19)
a
ꢀ
a
CeB distances lie in the region 1.685 (12) and 1.758 (11) A.
ꢀ
CeB distances lie between 1.699 (2) and 1.730 (2) A.
CeB distances lie between 1.683 (9) and 1.740 (9) A.
b
ꢀ
PdeSe distances are essentially similar and are as expected [25,26].
Various angles around each palladium atom are normal and lie in
2e4. The CeSe distances in all the complexes are similar to those
observed in selenocarboranes, e.g. (PhCbꢀSe)2 (1.947 A (av)) [15].
ꢀ
the range reported for [M2Cl2(m-Cl)(m-ER)(PR3)2] complexes [1]. The
The coordination environment around the metal atoms in 2 and
3 is distorted square planar and is defined by the two Se and two P
atoms of selenolate and tertiary phosphine ligands. In the former
the neutral atoms (P) are mutually trans disposed while in the latter
they occupy cis positions. Because of severe crowding from car-
boranes as well as phosphine ligands in 2 distortion in the coor-
dination environment around palladium is evident. Thus the
dihedral angles between “P2Pd” and “Se2Pd” and “P1Pd1Se2” and
“P2Pd1Se1” planes in 2 are 84.78(1) and 19.77ꢀ, respectively. The
P1ePd1eP2 and Se1ePd1eSe2 angles are also reduced to 160.30
and 176.85ꢀ, respectively from the ideal value of 180ꢀ. The carbor-
ane fragments in 2 are syn oriented with the phenyl groups
pointing outward while in 3 they are mutually anti. The two MeP
bonds in each molecule are essentially similar. However, the two
ꢀ
PdePd separation (3.2027 (6) A) is significantly large to account for
any PdePd interaction.
The molecular structure of 7 represents the first example of
asymmetric coordination environment around each metal centre
for the binuclear complexes of composition [M2X2(ER)2(PR3)2]
which are stabilized invariably by two bridging chalcogenolate
ligands [1]. Because of this asymmetry, there is significant distor-
tion around the metal atom. Coordination environment around one
of the palladium atoms is defined by two cis Se atoms, a bridging
chloride and a P atom while a P atom, two chlorides (one terminal
and another bridging) and a bridging Se surround the other palla-
dium atom. The four-membered ‘Pd2SeCl’ ring is puckered with the
hinge angle of 150.3ꢀ. To reduce steric crowding the two-carborane
fragments on two selenolate ligands are directed in opposite
directions. The palladium-bridging ligand distances are dissimilar
due to different trans influence of the terminal ligands. Accordingly
Pd(2)eSe(1) distance (trans to PEt3) is longer than the Pd(1)eSe(1)
ꢀ
MeSe distances in each molecule differ slightly (0.015 A) as has
been reported earlier for palladium/platinum selenolate complexes
[22]. Both MeP and MeSe distances are within the range reported
for mononuclear palladium/platinum selenolate complexes [11,22].
Complex 5 consists of two square planar palladium atoms which
are held together by one selenium and chlorine bridges, a configu-
ꢀ
bond length (trans to Cl) by w0.1 A. Similarly Pd(1)eCl(2) (trans to
ration observed for [M2Cl2(m-Cl)(m-ER)(PR3)2] complexes [1]. The
other two terminal chlorine atoms are in cis configuration. The
dihedral angle between “PdPSeCl2” planes is 48.02(3)ꢀ. The two
27.91
100
80
60
40
20
0
48.59
44.41
34.91
31.57
26.55
Table 3
The selected bond lengths (A) and angles ( ) for [Pd2Cl2(m-Cl)(m
-SeCboPh)(PMe2
ꢀ
ꢀ
-
Ph)2]a (5).
35.97
39.01
Pd1eSe1
Pd1eCl1
Pd1eCl2
Pd1eP1
2.3978 (6)
2.4031 (13)
2.3145 (13)
2.2301 (13)
1.963 (4)
Pd2eSe1
Pd2eCl1
Pd2eCl3
Pd2eP2
C1eC2
2.4070 (6)
2.4053 (13)
2.3272 (12)
2.2233 (13)
1.718 (6)
51.79
55.61
Se1eC1
C2eC3 (Ph)
1.508 (6)
Pd1ePd2
3.2027 (6)
59.17
61.99
Se1ePd1eCl1
Se1ePd1eCl2
Se1ePd1eP1
Pd1eSe1eC1
Cl1ePd1eCl2
Cl1ePd1eP1
Cl2ePd1eP1
Pd1eCl1ePd2
87.98 (3)
177.28
Se1ePd2eCl1
Se1ePd2eCl3
Se1ePd2eP2
Pd2eSe1eC1
Cl1ePd2eCl3
Cl1ePd2eP2
Cl3ePd2eP2
Pd1eSe1ePd2
87.72 (3)
177.87(4)
94.07 (4)
102.03 (14)
90.36 (5)
177.62 (5)
87.83 (5)
83.60 (2)
93.67 (4)
105.90 (14)
89.87 (5)
173.83 (5)
88.29 (5)
83.53 (4)
10
20
30
40
50
60
70
2θ
Fig. 5. XRD pattern of Pd17Se15 obtained from thermolysis of Pd(SeCboPh)2(PEt3)2 (2)
a
CeB distances lie in the region 1.705 (7) and 1.740 (7) A.
in HDA at 330 ꢀC.
ꢀ

2634
M.K. Pal et al. / Journal of Organometallic Chemistry 695 (2010) 2629e2634
for Basic Researches (Proposal No. RUSP-1005 and 10-03-92657-
IND).
Appendix A. Supplementary data
CCDC-Nos. 772666 (for 2), 772667 (for 5), 773677 (for 7) and
773678 (for 3) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
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Acknowledgements
We thank Drs. T. Mukherjee and D. Das for encouragement of
this work. Authors are grateful to the Department of Science and
Technology (DST), New Delhi and Russian Academy of Sciences,
Moscow for financial support under ILTP project No. B-5.22. This
work was also supported by grant of DST and Russian Foundation
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