Synthesis and crystal structures of trans-dichlorobis{tri(2-methylphenyl) stibine}palladium(II) and trans-dibromobis{tri(2-methylphenyl)stibine} palladium(II)

Article abstract of DOI:10.1016/j.ica.2004.10.036

Tri(2-methylphenyl)stibine reacts with [PdX₂(cod)] or PdX ₂ (X = Cl or Br) to give the trans-[PdX₂{Sb(2-Me- C ₆H₄)₃}₂]. The single crystal X-ray structures of trans-[PdX₂{Sb(2-Me-C₆H₄) ₃}₂] (X = Cl or Br) revealed that the palladium atom is a square planar environment with mutually trans-Sb(2-methylphenyl)₃ ligands. Iodine analogous of complex can also be prepared from trans metallation reaction with sodium iodine.

Full text of DOI:10.1016/j.ica.2004.10.036

Inorganica Chimica Acta 358 (2005) 1279–1283
www.elsevier.com/locate/ica
Note
Synthesis and crystal structures of
trans-dichlorobis{tri(2-methylphenyl)stibine}palladium(II) and
trans-dibromobis{tri(2-methylphenyl)stibine}palladium(II)
a,
b
Ayfer Mentes *, John Fawcett
a
Department of Chemistry, Arts and Science Faculty, Zonguldak Karaelmas University, 67100 Zonguldak, Turkey
b
X-ray Crystallography Laboratory, Department of Chemistry, The University of Leicester, Leicester, LE1 7RH, UK
Received 2 August 2004; accepted 29 October 2004
Available online 19 November 2004
Abstract
Tri(2-methylphenyl)stibine reacts with [PdX2(cod)] or PdX2 (X = Cl or Br) to give the trans-[PdX2{Sb(2-Me–C6H4)3}2]. The sin-
gle crystal X-ray structures of trans-[PdX2{Sb(2-Me-C6H4)3}2] (X = Cl or Br) revealed that the palladium atom is a square planar
environment with mutually trans-Sb(2-methylphenyl)3 ligands. Iodine analogous of complex can also be prepared from transmet-
allation reaction with sodium iodine.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Antimony; Crystal structures; Tri(2-methylphenyl)stibine; Palladium(II); Transmetallation
1. Introduction
the reaction of tri(2-methylphenyl)stibine with tetrachlo-
ropalladate(II) in aqueous acetone. Bromine and iodine
analogues were prepared from halide exchange reactions
with respective sodium salt [9]. These complexes were
characterised by elemental analysis, IR and melting
point.
Pt(II) complexes of triphenylstibine ligands showed
different geometry according to the halogen ligands such
as cis-[PtCl2(SbPh3)2] and trans-[PtI2(SbPh3)2] [13].
We have observed that reactions of palladium(II)
complexes with triphenylstibine can result in antimo-
ny-carbon bond cleavage [14]. The treatment of
[PdX2(cod)] (X = Cl or Br, cod = cyclo-octa-1,5-diene)
with triphenylstibine in refluxing dichloromethane af-
forded a bright yellow complex of trans-[PdXPh
(SbPh3)2]. The single crystal X-ray structures trans-
[PdClPh(SbPh3)2] and trans-[PdBrPh(SbPh3)2] were re-
ported [14].
The chemistry of organoantimony compounds has
been focused and the potentiality of such compounds
in organic synthesis either as reagents or as catalysts is
currently increasing [1–5]. Sb(2-Me-C6H4)3 ligands have
been used for palladium catalysed C-arylation reagents
of unsaturated compounds such as methyl acrylate and
palladium catalysed carbonylation reactions [1,5]. FT-
Raman and infrared spectra of some substituted triphe-
nyl derivatives of arsenic, antimony and bismuth are
measured [6]. Although the wealth of data on palladium
complexes with Group 15 elements is available, only a
few X-ray structures of Pd(II) coordination compounds
with stibine ligands are reported [7–12]. trans-
[PdCl2{Sb(2-Me-C6H4)3}2] complex is prepared from
*
Corresponding author. Tel.: +90 372 2574010/1373; fax: +90 372
We report here the synthesis of trans-[PdX2{Sb(2-Me-
C6H4)3}2] (X = Cl or Br) and X-ray structures of
2574181.
E-mail address: ayfermentes@yahoo.com (A. Mentes).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.10.036

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A. Mentes, J. Fawcett / Inorganica Chimica Acta 358 (2005) 1279–1283
trans-[PdX2{Sb(2-Me-C6H4)3}2] (X = Cl orBr). Compar-
isons have been made with analogous stibine complexes.
refluxed for 4 h. Solvent was removed by evaporation
and the residue was redissolved in dichloromethane.
Addition of diethyl ether gave orange crystals, which
were filtered off, washed with diethyl ether and dried
in vacuo. Recrystallisation from dichloromethane–
diethyl ether gave fine bright orange crystals of (1).
Yield 0.240 g (50% based on Pd). Analytical data
showed formation of the authentic complex of (1).
2. Experimental
All reactions were performed under a dry, oxygen-
free, nitrogen atmosphere, using solvents which were
dried and distilled under nitrogen just prior to use.
Microanalysis was carried out by Butterworth Labo-
ratories Ltd., 54-56 Waldegrave Rd., Teddington, Mid-
dlessex, TW11 8LG. Melting points were measured on a
Reichert hot stage apparatus and are uncorrected. The
FAB-mass spectra of the solid complexes were obtained
on a Kratos Concept Double Focusing Sector Mass
2.3. Preparation of trans-[PdBr2{Sb(2-Me-C6H4)3}2],
(2), from the reaction of tri(2-methylphenyl)stibine with
[PdBr2(cod)]
Tri(2-methylphenyl)stibine (0.319 g, 0.80 mmol) in
dichloromethane (5 cm3) was added to a solution of
[PdBr2(cod)] (0.1 g, 0.27 mmol) in dichloromethane
(10 cm3) and the solution was refluxed for 4 h. The solu-
tion was cooled to room temperature and diethyl ether
(10 cm3) was added and after several days fine orange-
red crystals of (2) were deposited. The filtered product
was washed with diethyl ether and dried in vacuo. Yield
0.20 g (70% based on Pd). C42H42Br2PdSb2 requires: C,
47.72; H, 3.97; Br, 15.15. Found: C, 48.6; H, 4.0; Br,
14.6%. M.p. 188–190 ꢁC (decomp.). IR.: m(Pd–Br)
240 cmÀ1. Mass spectrum: [M À Br]+ at m/z 977.
1
Spectrometer. The H NMR spectra were recorded at
room temperature in [2H1]chloroform on a BRUKER
ARX 250 spectrometer operating at 250.13 MHz with
SiMe4 (0.0 ppm) as internal reference. 13C-{1H} NMR
spectra were recorded at room temperature in [2H1]chlo-
roform on a BRUKER ARX 250 spectrometer operat-
ing at 62.9 MHz in CDCl3. The quoted IR spectra
were recorded on a Perkin–Elmer 580B spectrophotom-
eter in Nujol mulls between polythene plates in the range
600–200 cmÀ1
.
1
The compounds [PdCl2(cod)] [15], [PdBr2(cod)] [15],
and [Sb(2-Me-C6H4)3] [6] were prepared as described
in the literature.
NMR: H; d = 7.48–7.11 (24H, m, Arom.), 2.57 (18H,
s, –CH3) ppm. 13C–{1H}; d = 144.7, 136.9, 131.6,
130.9, 130.8, 126.8, 25.8 (CH3) ppm.
2.1. Preparation of trans-[PdCl2{Sb(2-Me-C6H4)3}2],
(1), from the reaction of tri(2-methylphenyl)stibine with
[PdCl2(cod)]
2.4. Preparation of trans-[PdBr2{Sb(2-Me-C6H4)3}2],
(2), from the reaction of tri(2-methylphenyl)stibine with
[PdBr2]
Tri(2-methylphenyl)stibine (0.415 g, 1 mmol) in
dichloromethane (5 cm3) was added to a solution of
[PdCl2(cod)] (0.1 g, 0.35 mmol) in dichloromethane
(10 cm3) and the solution was refluxed for 4 h. The solu-
tion was cooled to room temperature and diethyl ether
(10 cm3) was added and after several days fine orange
crystals of (1) were deposited. The filtered product was
washed with diethyl ether and dried in vacuo. Yield
0.208 g (61% based on Pd). C42H42Cl2PdSb2 requires:
C, 52.12; H, 4.34; Cl, 7.34. Found: C, 51.1; H, 4.2; Cl,
7.3%. M.p. 200–202 ꢁC (decomp.). IR.: m(Pd–Cl) 345
cmÀ1. Mass spectrum: [M À 2Cl]+ at m/z 896. NMR:
1H; d = 7.48–7.11 (24H, m, Arom.), 2.57 (18H, s, –
CH3) ppm. 13C–{1H}; d = 144.7, 136.8, 131.1, 130.9,
130.8, 126.8, 25.69 (CH3) ppm.
A solution of tri(2-methylphenyl)stibine (0.225 g, 0.56
mmol) in diethyl ether (10 cm3) was added to a suspen-
sion of PdBr2 (0.05 g, 0.18 mmol) in acetone (15 cm3)
and refluxed for 4 h. Solvent was removed by evapora-
tion and the residue was redissolved in dichloromethane.
Addition of diethyl ether gave orange crystals, which
were filtered off, washed with diethyl ether and dried
in vacuo. Recrystallisation from dichloromethane-
diethyl ether gave orange-red crystals of (2). Yield
0.055 g (28% based on Pd). Analytical data showed for-
mation of the authentic complex of (2).
Iodine analogue of the complex, trans-[PdI2{Sb(2-
Me-C6H4)3}2], has also been prepared by substitution
reaction of trans-[PdCl2{Sb(2-Me-C6H4)3}2], with NaI
in acetone.
2.2. Preparation of trans-[PdCl2{Sb(2-Me-C6H4)3}2],
(1), from the reaction of tri(2-methylphenyl)stibine with
[PdCl2]
3. Results and discussion
On the basis of infrared spectra complexes (1) and (2)
have been assigned a trans geometry as reported previ-
ously [9], exhibiting one m(Pd–X) stretching at 345, 240
cmÀ1, respectively.
A solution of tri(2-methylphenyl)stibine (0.660 g, 1.67
mmol) in diethyl ether (10 cm3) was added to a suspen-
sion of PdCl2 (0.1 g, 0.56 mmol) in acetone (15 cm3) and

A. Mentes, J. Fawcett / Inorganica Chimica Acta 358 (2005) 1279–1283
1281
Table 1
Crystal data and structure refinement for (1) and (2)
Emprical formula
C42H42Cl2PdSb2
C42H42Br2PdSb2
Formula weight (g/mol)
Temperature (K)
967.56
190(2)
1056.48
190(2)
˚
Wavelength (A)
0.71073
monoclinic
0.71073
monoclinic
P21/n
Crystal system
Space group
P21/n
10.704(2)
˚
a (A)
10.750(1)
11.299(2)
16.349(1)
94.98 (1)
1978.3(4)
2
˚
b (A)
11.185(1)
16.242(2)
˚
c (A)
b (ꢁ)
94.09 (1)
1939.6(5)
3
˚
V (A )
Z
2
1.657
Dx (Mg mÀ3
)
1.774
3.853
Absorption coefficient (mmÀ1
)
2.007
2.51–25.0
952
h Range (ꢁ)
F(000)
Crystal size (mm3)
Reflections collected
2.50–25.0
1024
0.40 · 0.25 · 0.14
4455
3421 (0.0225)
0.18 · 0.24 · 0.45
4417
3395 (0.0253)
Unique reflections (Rint
Index ranges
)
À1 6 h P 12, À1 6 k P 13, À19 6 l P 19
R1 = 0.0248, wR2 = 0.0652
R1 = 0.0278, wR2 = 0.0670
full-matrix least-squares on F2
3421/0/217
À1 6 h P 11, À1 6 k P 13, À19 6 l P 19
R1 = 0.0297, wR2 = 0.0676
R1 = 0.0399, wR2 = 0.0710
full-matrix least-squares on F2
3395/0/214
Final R indices [I > 2r(I)]
R indices (all data)
Refinement method
Data/restraints/parameters
Goodness-of fit on F2
Largest difference peak and hole (e A
0.993
0.773 and À0.455
1.063
0.540 and À0.563
À3
˚
)
Intensity data were measured on a Siemens P4 diffractometer, using an x-scan method. A semi empirical absorption correction was applied to the
data based on psi scans. The reflections were corrected for Lorentz and polarisation effects. The structures were solved by Patterson methods using
the program SHELXTL PC [18] and refined using the program SHELXL 93 [19] with full matrix least squares on F2. All non-hydrogen atoms were refined
with anisotropic displacement parameters.
Fig. 1. Molecular structure of (1) showing the atom numbering scheme and 50% displacement ellipsoids. H atoms are omitted for clarity. The Pd
atom is located on a centre of symmetry with primed atoms generated by Àx, 1 À y, 2 À z.

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A. Mentes, J. Fawcett / Inorganica Chimica Acta 358 (2005) 1279–1283
1H NMR and 13C–{1H} spectra of the complexes
˚
(2.3037(8) A) is longer than that found in the related
i
complex trans-[PdCl2(Sb Pr3)2] (2.2886(17) A) [11].
˚
have showed formation of trans-[PdX2{Sb(2-Me-
C6H4)3}2] complexes. Aromatic protons of the com-
plexes have multiplets at 7.48–7.11 ppm and methyl pro-
tons have singlet at 2.57 ppm.
Complex (2) (see Fig. 2) is isostructural with complex
˚
(1), with a Pd–Sb distance of (2.5685(3) A). The Pd–Br
˚
distance of (2.4177(5) A) is similar to that in the complex
˚
trans-[PdBrPh(SbPh3)2] (2.491(2) A) [14].
FAB-mass spectra of the complexes have showed ex-
pected fragmentation due to halogen ligand. The single
crystal X-ray structures of trans-[PdCl2{Sb(2-Me-
C6H4)3}2], (1), and trans-[PdBr2(Sb{2-Me- C6H4)3}],
(2), are described. The crystallographic data and data
collection details are given in Table 1.
The Pd–Cl and Pd–Br distances in (1) and (2) are
both shorter than those found in the ions [PdCl4]2À
2À
˚
˚
[16] (2.318 A) and [PdBr4] [17] (2.444(3) A), respec-
tively. The shorter observed distances are attributable
to the electronic effect of the stibine ligands.
The molecular structure of the complex (1) is shown
in Fig. 1 and selected bond distances and angles are gi-
ven in Table 2. The geometry at the palladium in (1) is
square planar with trans-tri(2-methylphenyl)stibine.
The reaction of tri(2-methylphenyl)stibine with
[PdX2(cod)] provides a convenient synthesis of the com-
plex trans-[PdX2{Sb(2-Me–C6H4)3}2] (X = Cl or Br).
Similarly, the reaction of tri(2-methylphenyl)stibine with
PdX2 in acetone–diethyl ether afforded trans-
[PdX2{Sb(2-Me-C6H4)3}2] (X = Cl or Br).
˚
The Pd–Sb distance (2.5658(3) A) is similar to those in
the palladium(II) complexes trans-[PdCl2(SbiPr3)2]
˚
(2.5721(7) A) [11] and trans-[PdI2(SbPh3)2] (2.578(1)
˚
A) [12]. The Pd–Cl(1) distance in complex (1)
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 41645 and 241646 for com-
pounds (1) and (2), respectively. Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
+44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk or
http://www.ccdc.cam.ac.uk).
Table 2
˚
Selected bond distances (A) and bond angles (ꢁ) with estimated
standard deviations in parentheses for (1) and (2)
(1)
(2)
2.139(5)
Sb(1)–C(11)
Pd(1)–Sb(1)
Pd(1)–X(1)
2.130(3)
2.5658(3)
2.3037(8)
88.78(2)
2.5685(3)
2.4177(5)
91.21(2)
X(1)–Pd(1)–Sb(1)
Fig. 2. Molecular structure of (2) showing the atom numbering scheme and 50% displacement ellipsoids. H atoms are omitted for clarity. The Pd
atom is located on a centre of symmetry with primed atoms generated by 1 À x, Ày, Àz.

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[8] N.R. Champness, W. Levason, Coord. Chem. Rev. 133 (1994)
115.
Acknowledgement
[9] C.A. McAuliffe, I. Eniven, R.V. Parish, Inorg. Chim. Acta 22
(1977) 239.
We thank Zonguldak Karaelmas University, Turkey,
for financial support and Johnson Matthey plc for the
loan of palladium metal salts.
[10] D. Negoiu, L. Paruta, Rev. Roum. Chim. 18 (1973)
2059.
[11] P.P. Phadnis, V.K. Jain, B. Varghese, Appl. Organometal. Chem.
16 (2002) 61.
[12] M. Mathew, G.J. Palenik, C.A. McAuliffe, Acta Crystallogr.,
Sect. C 43 (1987) 21.
References
[13] F.O. Wendt, A. Scodinu, L.I. Elding, Inorg. Chim. Acta 277
(1998) 237.
[1] D.V. Moiseev, A.V. Gushchin, A.S. Shavirin, Y.A. Kursky, V.A.
Dodonov, J. Organomet. Chem. 667 (2003) 176.
[2] K. Matoba, S. Motofusa, C.S. Cho, K. Ohe, S. Uemura, J.
Organomet. Chem. 574 (1999) 3.
[14] A. Mentes, R.D.W. Kemmitt, J. Fawcett, D.R. Russell, J.
Organomet. Chem. 528 (1997) 59.
[15] J. Chatt, L.M. Vallarino, L.M. Venanzi, J. Chem. Soc. (1957)
3413.
[3] A.B. Goel, H.J. Richards, J.H. Kyung, Tetrahedron Lett. 25
(1984) 391.
[16] R.H.B. Mais, P.G. Owston, A.M. Wood, Acta Crystallogr., Sect.
B 28 (1972) 393.
[4] A.B. Goel, H.J. Richards, J.H. Kyung, Inorg. Chim. Acta 76
(1983) L95.
[17] D.S. Martin, J.L. Bonte, R.M. Rush, R.A. Jacobson, Acta
Crystallogr. Sect. B 31 (1975) 2538.
[5] C.S. Cho, K. Tanabe, O. Itoh, S. Uemura, J. Org. Chem. 60
(1995) 274.
[18] G.M. Sheldrick, SHELXTL PC, Release 4.2, Siemens Analytical X-
Ray Instruments, Madison, WI, 1991.
, Program for Crystal Structure
[6] C. Ludwig, M. Dolny, H.J. Go¨tze, Spectrochim. Acta Part A 53
(1997) 2363.
[7] J. Chatt, L.M. Venanzi, J. Chem. Soc. (1957) 2351.
[19] G.M. Sheldrick, SHELXL 93
Refinement, University of Gottingen, 1993.
¨