Pyrazolato-bridged arylpalladium(II) complexes, [Pd2Ar 2(μ-pz/dmpz)2(PR3)2]: Synthesis and characterization

Article abstract of DOI:10.1016/j.jorganchem.2013.12.026

The reactions of [Pd₂Ar₂(μ-Cl)₂(PR ₃)₂] with pyrazole or 3,5-dimethylpyrazole in the presence of methanolic sodium hydroxide yield pyrazolato-bridged binuclear arylpalladium complexes, [Pd₂Ar₂(μ-pz′)₂(PR ₃)₂] (Ar = Ph or C₆H₄Me-4 (tol); pz′ = pz or dmpz; PR₃ = PEt₃, PMe₂Ph). These complexes exist exclusively in sym-trans form both in solution (by NMR) and in the solid state (by X-ray). The molecular structures of [Pd ₂tol₂(μ-Cl)₂(PMe₂Ph) ₂], [Pd₂tol₂(μ-pz)₂(PMe ₂Ph)₂] and [Pd₂tol₂(μ-dmpz) ₂(PEt₃)₂] have been established by X-ray diffraction analyses. The former is a centrosymmetric dimer while the latter two adopt a boat like conformation. The Pd?Pd separation in pyrazolato-bridged complexes is influenced by steric demands of particular pyrazolato-ligand.

Full text of DOI:10.1016/j.jorganchem.2013.12.026

Journal of Organometallic Chemistry 760 (2014) 55e59
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Pyrazolato-bridged arylpalladium(II) complexes,
[Pd2Ar2(
m
-pz/dmpz)2(PR3)2]: Synthesis and characterization
,
Kamal R. Chaudhari a, Amey P. Wadawale a, Mukesh Kumar b, Vimal K. Jain a
*
a Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
b Solid Sate Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The reactions of [Pd2Ar2(
m
-Cl)2(PR3)2] with pyrazole or 3,5-dimethylpyrazole in the presence of meth-
Received 25 September 2013
Received in revised form
9 December 2013
anolic sodium hydroxide yield pyrazolato-bridged binuclear arylpalladium complexes, [Pd2Ar2(m-
pz0)2(PR3)2] (Ar ¼ Ph or C6H4Me-4 (tol); pz0 ¼ pz or dmpz; PR3 ¼ PEt3, PMe2Ph). These complexes exist
exclusively in sym-trans form both in solution (by NMR) and in the solid state (by X-ray). The molecular
Accepted 11 December 2013
structures of [Pd2tol2(m-Cl)2(PMe2Ph)2], [Pd2tol2(m-pz)2(PMe2Ph)2] and [Pd2tol2(m-dmpz)2(PEt3)2] have
been established by X-ray diffraction analyses. The former is a centrosymmetric dimer while the latter
two adopt a boat like conformation. The Pd/Pd separation in pyrazolato-bridged complexes is influ-
enced by steric demands of particular pyrazolato-ligand.
Keywords:
Palladium
Arylpalladium
Pyrazolato
NMR
Ó 2013 Elsevier B.V. All rights reserved.
X-ray
1. Introduction
interesting photophysical properties [11,12] and have been
employed in catalytic reactions [13].
Organometallic chemistry of binuclear palladium(II) complexes
has been dominated by cyclometallated and
3-allyl derivatives [1e
In this paper we describe the synthesis and characterization of
binuclear pyrazolato-bridged arylpalladium(II) complexes.
h
5] with scant attention on alkyl and arylpalladium complexes. The
latter are believed to be the active intermediates in several organic
transformations involving arylhalides (e.g. Suzuki reaction) and
palladium compounds as catalysts [6,7]. Under exploration of the
chemistry of arylpalladium complexes may possibly be due to non-
availability of a convenient preparative route for a suitable synthon
2. Results and discussion
Treatment of chloro-bridged arylpalladium complexes
[Pd2Ar2(
presence of 2 mol equivalents of sodium hydroxide yielded bis
pyrazolato-bridged complexes, [Pd2Ar2(
-pz0)2(PR3)2] (eq. (1)). The
m-Cl)2(PR3)2] with pyrazoles in 1:2 stoichiometry in the
such as [Pd2Ar2(
m-Cl)2(L2)]. For the synthesis of the latter, Anderson
m
employed a reaction between [Pd2Cl2(m-Cl)2(PR3)2] and R2Hg [8],
latter could be recrystallized from benzene-hexane mixture as
colorless crystalline solids in 74e88% yield.
but the toxicity of mercury compounds and tedious process to
remove the side product (RHgCl) render this method of limited
utility. We have recently described a convenient synthesis of
[Pd2Ar2(
m
-Cl)2(PR3)2] þ 2 pz0H þ 2 NaOH / [Pd2Ar2(
m-
pz0)2(PR3)2] þ 2 NaCl þ 2 H2O
(1)
[Pd2Ar2(m-Cl)2(PR3)2] by employing triorganobismuth compounds
[7].
(Ar ¼ Ph or C6H4Me-4 (tol); pz0 ¼ pz or dmpz; PR3 ¼ PEt3 or
Pyrazolate/substituted pyrazolate ion is a versatile ligand in
stabilizing bi- and tri-nuclear metal complexes in which particular
moieties around metal ions or atoms are bridged by an exo-
bidentate pyrazolate ligand [9e11]. These complexes show
PMe2Ph)
The 1H and 13C NMR spectra of these complexes exhibited a
single set of resonances attributable to bridging pyrazolate group
indicating the existence of a sym-trans isomer in solution. For the
sym-cis isomer two sets of such resonances are expected. Inter-
estingly, the analogous platinum complexes [Pt2Ar2(
exist as a mixture of cis and trans isomer in solution and their
m
-pz0)2(PR3)2]
* Corresponding author. Tel.: þ91 22 2559 5095; fax: þ91 22 2550 5151.
E-mail address: jainvk@barc.gov.in (V.K. Jain).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.12.026

Table 1
Physical, analytical and NMR (1H, 13C, 31P) spectral data (in CDCl3) for [Pd2Ar2( -pz0)2(PR3)2].a
m
Complex
% Yield of
recrystallized
product
m.p.
(ꢀC)
% Analysis found (calc.)
NMR data
1H
C
H
N
13C
31P
[Pd2Ph2(
[Pd2Ph2(
m
-pz)2(PEt3)2]
(79)
180
49.65 (48.90)
5.90 (6.28)
7.49 (7.59)
1.13e1.26 (m, 18H, CH3CH2P), 1.40e1.45 (m, 12H,
CH2P), 5.92 (s, 2H, CHe4 of pz ), 6.92e7.54
(m, PdPh þ NCH ꢁ pz)
8.1 (s, CH3CH2P), 15.4 (d, CH2P,
J(PeC) ¼ 28 Hz), 102.7 (s,
C-4 of pz), 122.5, 126.8
138.4, 154.9 (C-1)(PdPh);
136.3, 137.2 (CHN-pz)
21.1
m-dmpz)2(PEt3)2]
(81)
150
51.26 (51.47)
6.69 (6.85)
6.94 (7.05)
1.10e1.15 (m, 18H, CH3CH2P), 1.58e1.73
(m, 12H, CH2P), 2.12, 2.24 (each s, Me of
dmpz), 5.41 (s, 2H, CH-4 of dmpz), 6.86e6.97
(m), 7.75 (d, 7 Hz, 4H, C6H4)
8.3 (s, CH3CH2P), 14.2,
16.1
14.8 (each s, Me of dmpz),
16.3 (d, 1J(PeC) ¼ 28 Hz,
CH2P), 102.0 (s, C-4 of
dmpz), 122.2 (s, C6H5),
125.9 (s, C6H5), 138.1
(s, C6H5), 144.7 (s, 5-C
of dmpz), 147.4 (s, 3-C of
dmpz), 152.0 (s, C-1 of C6H5)
8.1 (s, CH3CH2P), 15.3 (d,
1J(PeC) ¼ 29 Hz CH2P), 20.9
(s, Me of tol), 102.7 (s, C-4 of
pz), 135.8, 137.0 (CHN, pz);
127.7, 138.1 (CH-tol); 131.4
(C-4, tol); 149.7 (C-1, tol)
8.4 (s, CH3CH2P), 14.2, 14.8
(each s, Me of dmpz), 16.3
(d, J(PeC) ¼ 28 Hz, CH2P),
20.8 (s, Me of tol), 102.0
(s, , C-4 of dmpz ), 126.9
(s, tol CH), 129.4 (s, dmpz),
131.1 (s, C-4 tol), 137.7
[Pd2tol2(
[Pd2tol2(
m
-pz)2(PEt3)2]
(82)
(88)
190
190
50.05 (50.20)
53.2 (52.62)
5.81 (6.58)
6.89 (7.11)
7.87 (7.32)
2.04 (6.82)
1.11e1.21 (m, CH3CH2P); 1.39e1.44 (m, CH2P);
2.23 (s, tol, Me); 5.92 (s, CH-4, pz); 7.00, 7.22
(each s, pz); 6.82, 7.41 (each d, 7.5 Hz)
21.3
16.4
m-dmpz)2(PEt3)2]
1.07e1.17 (m, CH3CH2P); 1.62e1.74 (m, CH2P);
2.09 (s, tol, Me); 2.21, 2.23 (each s, Me, dmpz);
5.39 (s, CH-4, dmpz); 6.78, 7.58 (each, d, 7.8 Hz, tol)
(s, tol CH), 144.7 (s,
dmpz), 147.0 (C-1, tol)
14.1, 15.4 (each d,
[Pd2Ph2(
m
-pz)2(PMe2Ph)2]
(78)
(88)
(74)
140
165
130
52.33 (52.52)
54.94 (54.75)
53.80 (53.67)
4.76 (4.92)
5.50 (5.56)
5.1 (5.25)
e
1.20, 1.29 (each d, 2J(PeH) ¼ 10 Hz, PMe2), 5.83
(s, 2H, H-4, pz), 6.91 (br, CHN); 6.99 (t, Ph); 7.15
(s, CHN, pz); 7.39e7.79 (m, Ph)
1.8
0.4
1.9
1J(PeC) ¼ 33 Hz, PMe2), 103.0
(s, C-4, pz), 136.5, 137.5 (each s,
CHN, pz); 122.6, 126.9, 138.3,
154.2 (C-1) (PdePh) 128.6 (d,
10 Hz); 130.1 (s); 131.4 (d,
11 Hz) (PPh)
[Pd2Ph2(
m-dmpz)2(PMe2Ph)2]
e
1.36, 1.42 (each d, 10.5 Hz, Me2P), 2.04, 2.19
(each s, Me of dmpz), 5.44 (s, 2H, CH-4 of
dmpz), 6.89 (m, 6H, 3, 4, 5, C6H5Pd), 7.37e7.85 (m, Ph)
14.3, 14.6 (each d, J(PeC) ¼ 32,
39 Hz, Me2P), 15.2 (s, Me) 102.2
(s, C-4 of dmpz); 144.9, 147.1 (each s,
CHN, dmpz); 122.3 (s), 126.2 (s),
138.0 (s), 151.9 (C-1)[PdePh]
128.3, 130.2, 132.2 (d,
10 Hz); 134.5 (d, C-1) [PPh]
14.2, 15.5 (each d, J(PeC) ¼ 33 Hz,
PMe2), 20.9 (s, Me, tol), 102.9 (s,
C-4 of pz), 136.2, 137.5 (each s,
CHN, pz); 127.9, 135.1 (C-4), 138.2,
149.2 (C-1) [Pd-tol] ; 128.6 (d, 10 Hz);
130.1 (s); 131.5 (d, 11 Hz),
134.5 (d, C-1) [PPh]
[Pd2tol2(
m
-pz)2(PMe2Ph)2]
6.74 (6.95)
1.21, 1.30 (each d, J(PeH) ¼ 9.5 Hz, PMe2),
2.25 (s, 6H, CH3C6H4), 5.84 (s, 2H, CH-4
of pz), 6.83e7.82 (m, tol þ pz)

K.R. Chaudhari et al. / Journal of Organometallic Chemistry 760 (2014) 55e59
57
relative concentration varies from one preparation to another [14].
The 31P NMR spectra (Table 1) displayed single resonances indi-
cating the presence of only one isomeric species in solution. These
resonances are considerably shielded with respect to the signals for
the corresponding chloro-bridged [Pd2Ar2(
(PR3 ¼ PEt3 (w27.0 ppm) and PMe2Ph (w3.8 ppm)) [7].
The molecular structures of [Pd2tol2( -Cl)2(PMe2Ph)2],
[Pd2tol2( -pz)2(PMe2Ph)2] and [Pd2tol2( -dmpz)2(PEt3)2] with
m-Cl)2(PR3)2] derivatives
m
m
m
atomic numbering scheme are shown in Figs. 1e3 and the selected
interatomic parameters are listed in Tables 2e4.
The complex [Pd2tol2(m-Cl)2(Me2Ph)2] is a centrosymmetric
sym-trans dimer with the inversion center lying in the planar
Pd2Cl2 ring. The two distorted square-planar metal centers are
held together by bridging chloride ligands. The coordination
environment around each palladium atom is defined by two cis
bridging Cl atoms, phosphorus of PMe2Ph and a C-
a carbon atom
of the aryl group. Various interatomic parameters are similar to
those reported for [Pd2tol2(
Cl)2(PMe2Ph)2] [7].
m
-Cl)2(PEt3)2] and [Pd2Ph2(
m
-
-
The complexes, [Pd2tol2(m-pz)2(PMe2Ph)2] and [Pd2tol2(
m
dmpz)2(PEt3)2] are comprised of two square-planar metal frag-
ments which are held together by two pyrazolato bridges. Both
complexes have similar sym-trans geometry around palladium
atom which can be defined by two cis pyrazolato nitrogen atoms,
aryl carbon atom and the phosphorus atom. The molecules adopt a
boat like conformation as is observed for pyrazolate bridged
binuclear palladium and platinum complexes [1,12,15,16]. The Pde
N bond distances vary between 2.091(13) and 2.130(6) Å with the
distances trans to PdeC being slightly longer reflecting stronger
trans influence of the aryl group than the phosphine ligand. These
values are in accord with those reported for pyrazolato-bridged
palladium complexes [1,15]. The PdeC and PdeP bond distances
are well in agreement with the reported values, e.g. [Pd2tol2(m-
ꢀ
ꢀ
Cl)2(PEt3)2] (PdeC ¼ 1.992(8) A and PdeP ¼ 2.216(2) A) [7].
The nature of bridging pyrazolate ligand governs the Pd/Pd
separation. The Pd/Pd separation in pz-bridged complex (3.645 A)
is longer than the dmpz-bridged (3.395 A) derivative. The effect of
ꢀ
ꢀ
substituent in pyrazolate group on metalemetal separation has
been reported in [Pt2(CXN)2(pz0)2] (CXN ¼ 2-(2,4-difluorophenyl)
pyridine; pz0 ¼ pyrazolate, 3,5-dimethylpyrazolate, 3-methyl-5-
tert-butylpyrazolate and 3,5-bis(tert-butyl)pyrazolate) [12]. The
Pd/Pd separation in [Pd2tol2(m-dmpz)2(PEt3)2] is much longer
than the analogous chloro derivative [Pd2Cl2(
(Pd/Pd ¼ 3.115 A) [15].
m-dmpz)2(PMe2Ph)2]
ꢀ
Fig. 1. ORTEP diagram of [Pd2tol2(
m-Cl)2(PMe2Ph)2] (ellipsoids with 25% probability)
(hydrogen atoms are omitted for clarity).

58
K.R. Chaudhari et al. / Journal of Organometallic Chemistry 760 (2014) 55e59
Fig. 2. ORTEP diagram of [Pd2tol2(
m
-pz)2(PMe2Ph)2]$C6H6 (ellipsoids with 25% probability) (solvent molecule and hydrogen atoms are omitted for clarity).
Fig. 3. ORTEP diagram of [Pd2tol2(
m-dmpz)2(PEt3)2] (ellipsoids with 25% probability) (hydrogen atoms are omitted for clarity).
3. Experimental
atmosphere in dry and distilled solvents. Microanalyses were car-
ried out on a Thermo Fischer EA 1110-CHNS instrument. The 1H, 13
C
3.1. Materials and methods
{1H} and 31P{1H} NMR spectra were recorded in CDCl3 on a Bruker
Avance-II 300 MHz NMR spectrometer operating at 300.13, 75.47
and 121.49 MHz, respectively. Chemical shifts are relative to inter-
nal CHCl3 for 1H and 13C NMR spectra and external 85% H3PO4 for
31P NMR spectra.
The complexes [Pd2Ar2(
m
-Cl)2(PR3)2] (Ar ¼ Ph, 4-MeC6H4 (tol);
PR3 ¼ PEt3, PMe2Ph) were prepared according to literature method
[7]. Pyrazole and 3,5-dimethylpyrazole were obtained from com-
mercial sources. All reactions were carried out under an argon
3.2. Syntheses
Table 2
ꢀ
ꢀ
Selected bond lengths (A) and angles ( ) for [Pd2tol2(m-Cl)2(PMe2Ph)2].
3.2.1. Synthesis of [Pd2tol2(
To a suspension of [Pd2tol2(
in methanol was added a solution of pyrazole (11 mg, 0.161 mmol)
m
-pz)2(PEt3)2]
Pd1eCl1
Pd1ieCl1
Pd1eP1
2.420(2)
2.449(2)
2.216(2)
Pd1eC1
1.992(8)
3.574
m-Cl)2(PEt3)2] (55 mg, 0.078 mmol)
Pd1/Pd1i
Table 4
Pd1ieCl1ePd1
Cl1iePd1eCl1
C1ePd1eCl1
P1ePd1eCl1
94.46(8)
85.54(8)
91.4(2)
C1ePd1eCl1i
P1ePd1eCl1i
C1ePd1eP1
175.5(2)
98.21(8)
84.9(2)
ꢀ
ꢀ
Selected bond lengths (A) and angles ( ) for [Pd2tol2(
m
-dmpz)2(PEt3)2].
C6ePd1
P1ePd1
N1ePd1
N4ePd1
N2eN1
2.040(6)
2.2608(19)
2.130(6)
2.091(6)
1.366(8)
C24ePd2
P2ePd2
N2ePd2
N3ePd2
N4eN3
Pd1/Pd2
C24ePd2eP2
N3ePd2eP2
N2ePd2eP2
C24ePd2eN3
C24ePd2eN2
N2ePd2eN3
N4eN3ePd2
N3eN4ePd1
2.020(7)
2.251(2)
2.098(6)
2.117(6)
1.350(8)
3.395
176.00(8)
Table 3
Selected bond lengths (A) and angles ( ) for [Pd2tol2(
ꢀ
ꢀ
m
-pz)2(PMe2Ph)2]$C6H6.
Pd1eC4
P1ePd1
Pd1eN1
1.998(17)
2.251(4)
2.091(13)
Pd1eN2i
N1eN2
2.107(13)
1.359(17)
3.645
C6ePd1eP1
N1ePd1eP1
N4ePd1eP1
C6ePd1eN1
C6ePd1eN4
N4ePd1eN1
N2eN1ePd1
N1eN2ePd2
85.8(2)
97.93(15)
177.51(16)
175.7(2)
91.7(2)
86.8(2)
96.00(18)
172.08(19)
172.8(3)
91.7(3)
86.4(2)
122.0(4)
116.0(4)
Pd1/Pd1i
C4ePd1eP1
N1ePd1eP1
N2iePd1eP1
C4ePd1eN1
86.7(5)
95.3(4)
175.1(4)
176.2(7)
C4ePd1eN2i
N1ePd1eN2i
N2eN1ePd1
N1eN2ePd1i
89.1(1)
88.7(5)
123.2(10)
122.3(10)
84.5(2)
119.1(4)
117.4(4)

K.R. Chaudhari et al. / Journal of Organometallic Chemistry 760 (2014) 55e59
59
Table 5
Crystallographic data and structural refinement details for [Pd2tol2(
m
-Cl)2(PMe2Ph)2], [Pd2tol2(
m-pz)2(PMe2Ph)2]$C6H6 and [Pd2tol2(
m-dmpz)2(PEt3)2].
Complex
[Pd2tol2(
m
-Cl)2(PMe2Ph)2] [Pd2tol2(
m
-pz)2(PMe2Ph)2]$C6H6
[Pd2tol2(m-dmpz)2(PEt3)2]
Chemical formula
Formula weight
Crystal size (mm3)
Crystal system
C30H36Cl2P2Pd2
742.23
0.10 ꢂ 0.10 ꢂ 0.02
Orthorhombic
Pbca
C36H42N4P2Pd2. C6H6
883.58
0.30 ꢂ 0.20 ꢂ 0.10
Orthorhombic
Fdd2
C36H58N4P2Pd2
821.60
0.18 ꢂ 0.14 ꢂ 0.04
Monoclinic
P21/c
Space group
Unit cell dimensions
ꢀ
a (A)
13.4798(9)
14.1654(11)
16.1889(9)
90.00
90.00
90.00
3091.2(4)
1.595
4
12.081/1488
ꢁ16 ꢄ h ꢄ 9
17 ꢄ k ꢄ 16
-19 ꢄ l ꢄ 8
5.29e70.09
2862/2028
2862/0/167
0.0636/0.1741
0.0906/0.1994
1.088
11.5157(12)
15.800(4)
44.185(8)
90
90
90
8039.0(3)
1.460
8
1.008/3600
ꢁ14 ꢄ h ꢄ 8
ꢁ11 ꢄ k ꢄ 20
0 ꢄ l ꢄ 57
2.59e27.47
3501/2778
2778/1/227
0.0601/0.1216
0.1125/0.1674
1.227
12.7222(4)
17.3525(3)
18.6587(5)
90.00
107.149(3)
90.00
3936.0(2)
1.356
4
8.346/1696
ꢁ11 ꢄ h ꢄ 15
ꢁ20 ꢄ k ꢄ 20
ꢁ22 ꢄ l ꢄ 22
3.55e70.12
7329/5758
7329/5/409
0.0630/0.1806
0.0857/0.1953
1.108
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢀ)
(ꢀ)
(ꢀ)
3
ꢀ
Volume (A )
r
Z
m
calcd. (g cmꢁ3
)
(mmꢁ1)/F(000)
Limiting indices
q
Range of data collection (ꢀ)
Reflections collected/unique
Data/restraints/parameters
Final R1,
R1, R2 (all data)
Goodness of fit on F2
uR2 indices
u
in methanolic (10 cm3) sodium hydroxide (6 mg, 0.15 mmol). The
mixture was stirred at room temperature for 5 h, the solvent was
evaporated in vacuo and the residue was extracted with dichloro-
methane (3 ꢂ 5 cm3). This solution was concentrated to 5 ml and
after adding hexane, gave colorless crystals of the title complex
(49 mg, 82% yield). Similarly all other complexes were prepared
and pertinent data are summarized in Table 1.
Appendix A. Supplementary material
CCDC 962919, 962920 and 962921 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.
References
3.3. Crystallography
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[2] V.K. Jain, L. Jain, Coord. Chem. Rev. 254 (2010) 2848e2903.
[3] M. Albrecht, Chem. Rev. 110 (2010) 576e623.
[4] S. Kolay, A. Wadawale, D. Das, H.K. Kisan, R.B. Sunoj, V.K. Jain, Dalton Trans. 42
(2013) 10828e10837.
[5] L.B. Kumbhare, A. Wadawale, S.S. Zade, V.K. Jain, Dalton Trans. 40 (2011)
7957e7966.
[6] C.C.C.J. Seechurn, M.O. Kithching, J.J. Colacot, V. Sneickus, Angew. Chem. Int.
Ed. 51 (2012) 5062e5085.
Intensity data of [Pd2tol2(
on a Rigaku AFC 7S diffractometer fitted with Mo-K
radiation while the data for [Pd2tol2( -Cl)2(PMe2Ph)] and
[Pd2tol2( -dmpz)2(PEt3)2] were collected on Agilent SuperNova,
Titan fitted with Cu-K
(298 ꢃ 2 K). The intensity data were corrected for Lorenz, polari-
zation and absorption effects with an empirical procedure [17,18].
The structures were solved by direct methods [19] and refinement
was on F2 [20]. The non-hydrogen atoms were modeled with
anisotropic displacement parameters while the hydrogen atoms
were fixed in their calculated positions. Molecular structures were
drawn using ORTEP [21]. Crystal data and refinement details are
given in Table 5.
m-pz)2(PMe2Ph)2]$C6H6 were collected
ꢀ
a (l-0.71069 A)
m
m
ꢀ
a
(l-1.54184 A) at room temperature
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Approximation, Rigaku Corporation, 3-9-12 Matsubara, Akishima, Japan,
1995.
4. Conclusion
A convenient preparation for binuclear arylpalladium com-
plexes [Pd2Ar2(m-Cl)2(PR3)2] has been described and its utility for
the synthesis of pyrozolato-bridged complexes has been demon-
strated. The Pd/Pd separation in the pyrazolato complexes is
influenced by the nature of the substituent in the pyrazolato ring.
[18] A.C.T. North, D.C. Phillips, F.S. Mathews, PSISCANS, Acta. Crystallogr. Sect A 24
(1968) 351e359.
[19] A. Altomase, G. Cascarano, C. Gracovazzo, A. Guagliardi, J. Appl. Crystallogr. 26
(1993) 343e350.
[20] G.M. Sheldrick, SHELX97, Programs for the Solution of Crystal Structure,
University of Göttingen, Germany, 1997.
Acknowledgments
[21] C.K. Johnson, ORTEP-III, Report ORNL-5136, Oak Ridge National Laboratory,
Oak Ridge, TN, 1976.
Authors thank Dr. B. N. Jagatap for encouragement of this work.