Synthesis and transition metal chemistry of new bromo- and alkyl substituted phosphinite ligands

Article abstract of DOI:10.1016/j.poly.2012.02.016

Ligands Ph₂P(OAr) (Ar = 2,4,6-C₆H₂Br ₃, 1; Ar = C₆H₃(o-OMe)(p-C₃H ₅), 2) were prepared by treating PPh₂Cl with tribromo phenol and eugenol, respectively, in good yields. The reaction of Ph ₂P(OAr) with [Pd(COD)Cl₂] in 2:1 molar ratio yielded trans-[Pd{PPh₂(OAr)}Cl₂] (4) and cis-[Pd{PPh ₂(OAr)}Cl₂] (5), respectively. The chloro-bridged dipalladium complex [Pd₂{PPh₂(OAr)}₂Cl ₄] (6) was obtained in the 1:1 reaction between 2 and [Pd(COD)Cl ₂], along with 5 as a minor product. Mononuclear complexes, [Au{PPh₂(OAr)}Cl] (Ar = 2,4,6-C₆H₂Br ₃, 7; Ar = C₆H₃(o-OMe)(p-C₃H ₅), 8) and [(Ru(η⁶-p-cym){PPh₂(OAr)}Cl ₂] (9) were prepared by reacting ligands 1 and 2 with [AuCl(SMe ₂)] and [(Ru(η⁶-p-cym)Cl₂]₂, respectively. All the complexes were characterized by ³¹P, ¹H NMR and elemental analyses data.

Full text of DOI:10.1016/j.poly.2012.02.016

Polyhedron 38 (2012) 97–102
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and transition metal chemistry of new bromo- and alkyl substituted
phosphinite ligands
Susmita Naik a, Nallbothula Durganna a, Shaik M. Mobin b, Joel T. Mague c, Maravanji S. Balakrishna a,
⇑
a Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India
b National Single Crystal X-ray Diffraction Facility, Indian Institute of Technology Bombay, Mumbai 400 076, India
c Department of Chemistry, Tulane University, New Orleans, LA 70118, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Ligands Ph2P(OAr) (Ar = 2,4,6-C6H2Br3, 1; Ar = C6H3(o-OMe)(p-C3H5), 2) were prepared by treating PPh2Cl
with tribromo phenol and eugenol, respectively, in good yields. The reaction of Ph2P(OAr) with
[Pd(COD)Cl2] in 2:1 molar ratio yielded trans-[Pd{PPh2(OAr)}Cl2] (4) and cis-[Pd{PPh2(OAr)}Cl2] (5),
respectively. The chloro-bridged dipalladium complex [Pd2{PPh2(OAr)}2Cl4] (6) was obtained in the 1:1
reaction between 2 and [Pd(COD)Cl2], along with 5 as a minor product. Mononuclear complexes, [Au
Received 30 January 2012
Accepted 14 February 2012
Available online 3 March 2012
{PPh2(OAr)}Cl] (Ar = 2,4,6-C6H2Br3, 7; Ar = C6H3(o-OMe)(p-C3H5), 8) and [(Ru(
(9) were prepared by reacting ligands 1 and 2 with [AuCl(SMe2)] and [(Ru(
6-p-cym)Cl2]2, respectively.
All the complexes were characterized by 31P, 1H NMR and elemental analyses data.
Ó 2012 Elsevier Ltd. All rights reserved.
g
6-p-cym){PPh2(OAr)}Cl2]
Keywords:
Phosphinite
Ruthenium
Palladium
Gold complexes
Chloro-bridged dimer
Crystal structure
g
1. Introduction
(OAr)2
P
O
The preparation of functionalized phosphine, phosphinite as
well as phosphonite ligands have attracted considerable interest
in recent years [1]. Besides their utility in coordination chemistry,
they are widely employed as homogeneous catalysts in a variety of
organic transformations [2]. These ligands are known to form a
wide range of interesting metal complexes depending upon the
nature of metal precursors, stoichiometry and the reaction condi-
O
O
PPh2
Pd TfA
PPh2
Cl
2
tBu
Pd
R
tBu
Ar= C6H3-2,4-(tBu)2
R= H, Me
I
II
tions. Recently, alkyl phosphines with strong
r-donor ability have
2. Experimental
attracted much attention due to their high catalytic activity espe-
cially when bound to palladium [3,4]. Orthopalladated triar-
ylphosphite or phosphinite complexes of the type I and II have
shown excellent activity in the Suzuki coupling of aryl bromides,
arylation of alkenes, ethylation of phenols, etc. [5–8]. Palladium
complexes containing phosphinite ligands [PPh2(OR)] and related
compounds are also known for promoting carbon–carbon bond
formation reactions [9]. As a part of our interest in designing novel
ligands for catalytic utility, we reported in this paper two different
kinds of ligands, one in which two ortho positions of the hydroxyl
groups are blocked, whereas in other, one of the ortho positions is
kept free to explore the possibility of ortho activation while study-
ing their coordination behaviour with late transition metals.
2.1. General consideration
All experimental manipulations were performed under an inert
atmosphere of dry nitrogen or argon, using standard Schlenk
techniques. All the solvents were purified by conventional proce-
dures and distilled prior to use. [Pd(COD)Cl2] [10], [Pd(allyl)Cl]2
[11], [Ru(g
6-cymene)Cl2]2 [12], [AuCl(SMe2)] [13] were prepared
according to the published procedures. Other reagents were
obtained from commercial sources and used after purification.
The 1H and 31P{1H} NMR (d in ppm) spectra were obtained on a
Varian VRX 400 spectrometer operating at frequencies of 400 and
162 MHz, respectively. The spectra were recorded in CDCl3 (or
DMSO-d6) solutions with CDCl3 (or DMSO-d6) as an internal lock;
TMS and 85% H3PO4 were used as internal and external standards
for 1H and 31P{1H} NMR, respectively. Positive values indicate
downfield shifts. Microanalyses were carried out on a Carlo Erba
⇑
Corresponding author. Tel.: +91 22 2576 7181; fax: +91 22 2572 3480.
E-mail address: krishna@chem.iitb.ac.in (M.S. Balakrishna).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2012.02.016

98
S. Naik et al. / Polyhedron 38 (2012) 97–102
(model 1106) elemental analyzer. Melting points of all compounds
were determined on a Veego melting point apparatus and are
uncorrected.
C
44H42Cl2O4P2PdꢁCH2Cl2: C, 56.36; H, 4.62. Found: C, 56.22; H,
4.52%.
2.1.6. Synthesis of [Pd{PPh2(OAr)}2Cl2] (5) and [Pd2{PPh2(OAr)}2Cl4]
(6)
2.1.1. Synthesis of Ph2P(OAr) (Ar = 2,4,6–C6H2Br3) (1)
A solution of PPh2Cl (0.67 g, 3.04 mmol) in diethyl ether (10 mL)
was added drop wise to a mixture of 2,4,6-tribromophenol (1.0 g,
3.04 mmol) and triethyl amine (0.46 g, 4.55 mmol) also in diethyl
ether (30 mL) at 0 °C with vigorous stirring. The reaction mixture
was warmed to room temperature and stirring was continued
overnight. The triethyl amine hydrochloride formed was filtered
through Celite and the solvent was removed under reduced pres-
sure to get the product as white crystalline solid. Yield: 92%
(1.42 g). Mp: 78–80 °C. 1H NMR (400 MHz, CDCl3): d 7.39–7.73
(m, ArH, 12H). 31P NMR (162 MHz, CDCl3): d 126.3 (s). Anal. Calc.
for C18H12Br3OP: C, 41.98; H, 2.35. Found: C, 42.31; H, 2.27%.
A solution of Pd(COD)Cl2 (0.022 g, 0.08 mmol) in dichlorometh-
ane (5 mL) was added drop wise to the solution of 2 (0.027 g,
0.08 mmol) in the same solvent (5 mL) with constant stirring and
the stirring was continued for 4 h at room temperature. The sol-
vent was removed under reduced pressure; the residue obtained
was washed with petroleum ether to get 6 as yellow crystalline so-
lid. Yield: 75% (0.038 g). 1H NMR (400 MHz, CDCl3): d 3.26 (d, CH2,
3
4H, JHH = 6.4 Hz), 3.69 (s, OMe, 6H), 4.89–5.07 (m, @CH2, 4H)
5.78–5.97 (m, @CH, 2H), 6.26–7.89 (m, ArH, 26H). 31P NMR
(162 MHz, CDCl3): d 114.7 (s) and 107 (s).
2.1.7. Synthesis of [Au{PPh2(OAr)}Cl] (7)
2.1.2. Synthesis of PPh2(OAr) (Ar = C6H3(o-OMe)(p-C3H5)) (2)
A solution of [AuCl(SMe2)] (0.025 g, 0.0846 mmol) in dichloro-
methane (5 mL) was added drop wise to the solution of 1
(0.044 g, 0.0845 mmol) also in dichloromethane (5 mL) and the
reaction mixture was stirred for 4 h at room temperature. The sol-
vent was removed under reduced pressure; the residue obtained
was washed with petroleum ether to get white crystalline product.
Yield: 92% (0.058 g). Mp: >196 °C (decomp). 1H NMR (400 MHz,
CDCl3): d 7.49–7.95 (m, ArH, 12H). 31P NMR (162 MHz, CDCl3): d
121.4 (s). Anal. Calc. for C18H12Br3OPAuClꢁ2CH2Cl2: C, 26.19; H,
1.76. Found: C, 25.95; H, 1.74%.
A solution of PPh2Cl (0.67 g, 3.04 mmol) in diethyl ether (10 mL)
was added drop wise to a mixture of 2-methoxy-4-allylphenol
(0.5 g, 3.04 mmol) and triethyl amine (0.46 g, 4.55 mmol) in the
same solvent (30 mL) at 0 °C with vigorous stirring. The reaction
mixture was warmed to room temperature and stirring was con-
tinued overnight. The triethyl amine hydrochloride was filtered
through Celite and the solvent was removed under reduced pres-
sure to get colourless oily product. Yield: 93% (0.98 g). 1H NMR
3
(400 MHz, CDCl3): d 3.31 (d, CH2, 2H, JHH = 6.4 Hz), 3.78 (s, OMe,
3H), 5.04–5.09 (m, @CH2, 2H), 5.92–5.94 (m, @CH, 1H), 6.62–7.65
(m, ArH, 13H). 31P{1H} NMR (162 MHz, CDCl3): d 117.5 (s).
2.1.8. Synthesis of [Au{PPh2(OAr)}2Cl] (8)
A solution of [AuCl(SMe2)] (0.027 g, 0.0861 mmol) in dichloro-
methane (5 mL) was added drop wise to the solution of 2 (0.03 g,
0.0861 mmol) in the same solvent (5 mL) and the reaction mixture
was stirred for 4 h at room temperature. The solvent was removed
under reduced pressure and the oily residue obtained was washed
with petroleum ether to get analytically pure product of 8 as white
crystalline solid. Yield: 92% (0.058 g). Mp: >200 °C (decomp). 1H
2.1.3. Synthesis of [Pd(allyl){PPh2(OAr)}Cl] (3)
A solution of [Pd(g
3-allyl)Cl]2 (0.012 g, 0.0342 mmol) in dichlo-
romethane (5 mL) was added drop wise to the solution of 1
(0.035 g, 0.0682 mmol) also in dichloromethane (5 mL) with con-
stant stirring and the reaction mixture was stirred for 4 h at room
temperature. The solution was concentrated to 3 ml and 2 mL of
petroleum ether was added to get 3 as yellow solid. Yield: 89%
(0.045 g). Mp: 142–145 °C. 1H NMR (400 MHz, CDCl3): d 3.03 (d,
3
NMR (400 MHz, CDCl3): d 3.40 (d, CH2, 2H, JHH = 6.4 Hz), 3.81 (s,
OMe, 3H), 5.13–5.16 (m, @CH2, 2H), 5.94–6.05 (m, @CH, 1H),
6.68–7.94 (m, ArH, 13H). 31P NMR (162 MHz, CDCl3): d 117.0 (s).
Anal. Calc. for C22H21ClO2PAu: C, 45.50; H, 3.64. Found: C, 45.62;
H, 3.56%.
3
3
CH2, 2H, JHH = 12.4 Hz), 4.11 (d, CH2, 2H, JHH = 5.99 Hz), 5.47 (m,
CH, 6H), 7.36–7.90 (m, ArH, 12H). 31P{1H} NMR (162 MHz, CDCl3):
d 130.2 (s). Anal. Calcd for C21H18Br3OPPdCl: C, 36.09; H, 2.60.
Found: C, 36.24; H, 2.48%.
2.1.9. Synthesis of [Ru(
dichloromethane (5 mL) solution of [Ru(g
6-p-Cym)Cl2]2
g
6-p-Cym){PPh2(OAr)}Cl2] (9)
2.1.4. Synthesis of trans-[Pd{PPh2(OAr)}2Cl2] (4)
A
A solution of Pd(COD)Cl2 (0.009 g, 0.032 mmol) in dichloro-
methane (5 mL) was added drop wise to the solution of 1
(0.033 g, 0.064 mmol) in the same solvent (5 mL) with constant
stirring and the stirring was continued for 4 h at room tempera-
ture. The volume of the solution was reduced to 2 mL, layered with
petroleum ether and kept at ꢀ20 °C for 24 h to get yellow crystals.
Yield: 82% (0.035 g). Mp: 162–164 °C. 1H NMR (400 MHz, CDCl3): d
7.25–7.75 (m, ArH 12H). 31P NMR (162 MHz, CDCl3): d 118.5 (s).
Anal. Calc. for C36H24Br6O2P2Pd2Cl2ꢁ2CH2Cl2: C, 33.14; H, 2.05.
Found: C, 32.94; H, 1.97%.
(0.025 g, 0.042 mmol) was added drop wise to the solution of 2
(0.029 g, 0.084 mmol) in the same solvent (5 mL) with constant
stirring and the stirring was continued for 4 h at room tempera-
ture. The solvent was removed under vacuo, the residue obtained
was washed with petroleum ether to get 9 as red crystalline solid.
Yield: 85% (0.049 g). Mp: 103–105 °C. 1H NMR (400 MHz, CDCl3): d
0.78 (d, CH3, 6H, 3JHH = 6.8 Hz), 1.37(s, CH3, 3H), 2.47 (sept, CH, 1H),
3
3.28 (d, CH2, 2H, JHH = 6.8 Hz), 4.04 (s, OMe, 3H), 5.02–5.07 (m,
3
@CH2, 2H) 5.21 (d, C6H4, 2H, JHH = 6.0 Hz), 5.31 (d, C6H4, 2H,
3JHH = 6.4 Hz), 5.83–5.93 (m, @CH, 1H), 6.56–8.12 (m, ArH, 13H).
31P{1H} NMR (162 MHz, CDCl3): d 114.4 (s). Anal. Calc. for
2.1.5. Synthesis of [Pd{PPh2(OAr)}2Cl2] (5)
C32H35Cl2O2PRu: C, 58.72; H, 5.39. Found: C, 58.57; H, 5.31%.
A solution of Pd(COD)Cl2 (0.029 g, 0.1026 mmol) in dichloro-
methane (5 mL) was added drop wise to the solution of 2
(0.071 g, 0.205 mmol) also in dichloromethane (5 mL) and the
reaction mixture was stirred for 4 h at room temperature. The sol-
vent was removed under reduced pressure and the residue was
washed with petroleum ether to obtain 5 as yellow crystalline so-
lid. Yield: 91% (0.092 g). Mp: >236 °C (decomp). 1H NMR (400 MHz,
2.2. X-ray crystallography
Single crystal X-ray structural study of 4 was performed on a
CCD Oxford Diffraction XCALIBUR-S diffractometer equipped with
an Oxford Instruments low-temperature attachment whereas crys-
tal of 9 was performed on a Bruker Smart Apex CCD diffractometer.
Data were collected at 150(2) K for 4 and 100(2) K for 9 using
3
CDCl3): d 3.17 (s, OMe, 6H), 3.18 (d, CH2, 4H, JHH = 6.8 Hz), 4.90–
5.03 (m, @CH2, 4H) 5.80–5.87 (m, @CH, 2H), 6.26–7.87 (m, ArH,
graphite-monochromoated Mo K
strategy for the data collection was evaluated by using the
a radiation (k = 0.71073 Å). The
a
26H). 31P{1H} NMR (162 MHz, CDCl3): d 114.7 (s). Anal. Calcd for

S. Naik et al. / Polyhedron 38 (2012) 97–102
PPh2
99
OH
R2
3. Results and discussion
O
R3
R1
PPh2Cl, Et3N, Et2O
0 o
RT, overnight
R3
R1
2,4,6-Tribromophenol was prepared by treating phenol with
hydrogen peroxide and concentrated hydrobromic acid according
to the reported procedure [17]. The tribromophenol so obtained
was dried under vacuum for longer time and used without further
purification. Treatment of one equivalent of chlorodiphenylphos-
phine with tribromophenol in diethyl ether in the presence of tri-
ethyl amine resulted in the formation of Ph2P(OAr) (Ar = 2,4,6-
C6H2Br3) (1). Similar reaction between PPh2Cl and 2-methoxy-4-al-
lyl phenol gave PPh2(OAr) (Ar = C6H3(o-OMe(p-C3H5)) (2) in good
yield (Scheme 1). The compound 1 is an air sensitive white solid
while compound 2 is an air and moisture sensitive viscous liquid
which was used in complexation reactions without further purifi-
cation. The 31P NMR spectra of compound 1 and 2 show sharp sing-
lets at 126.3 and 117.5 ppm, respectively. 1H NMR spectrum of
compound 1 shows a single peak at 3.84 ppm for the methoxy
group while the allylic –CH2 and allylic –CH show multiplets at
3.40 and 6.90 ppm, respectively.
C
R2
1
R1 = R2 = R3 = Br ( )
2
R1 = OMe, R2 = C3H5, R3 = H ( )
Scheme 1. Synthesis of 1 and 2.
CrysAlisPro CCD software. The data were collected by the standard
/q-scan techniques’ (for 4) or APEX2 programme suite (for 9) [14]
and were scaled and reduced using CrysAlisPro RED (for 4) or SAINT
‘nx
software (for 9) [15]. The structures were solved by direct methods
using SHELXS-97 and refined by full matrix least-squares with SHELXL
-
97, refining on F2 [16]. The positions of all the atoms were obtained
by direct methods. All non-hydrogen atoms were refined aniso-
tropically. The remaining hydrogen atoms were placed in geomet-
rically constrained positions and refined with isotropic
temperature factors, generally 1.2Ueq of their parent atoms.
The reaction between 1 and [Pd(
in dichloromethane afforded the mononuclear complex [Pd
g
3allyl)Cl]2 in 2:1 molar ratio
Cl
Br
O
Br
PPh2
Pd
Cl
O
PPh2
0.5 [Pd(allyl)Cl]2
CH2Cl2, RT, 4h
0.5 [Pd(COD)Cl2]
CH2Cl2, RT, 4h
Br
Br
O
Ph2P Pd PPh2
Br
Br
Br
Br
O
Cl
Br
Br
Br
Br
4
3
1
Scheme 2. Palladium complexes of 1.
Cl
Cl
Pd
Ph2P
O
PPh2
O
MeO
OMe
0.5 Pd(COD)Cl2
CH2Cl2, RT, 4h
OPPh2
MeO
5
Cl
Cl
Pd
Ph2
P
Ph2P
PPh2
MeO
OMe
MeO
Cl
Cl
O
Pd(COD)Cl2
CH2Cl2, Δ, 24h
+
O
O
Pd
Pd
2
P
O
Cl
Cl
OMe
Ph2
5
6
Scheme 3. Reactions of 2 with Pd(COD)Cl2.
R2
R2
R1
Cl
OPPh2
Cl
R3
R1
[Ru(cymene)Cl2]2
CH2Cl2, RT, 4h
AuCl(SMe2)
CH2Cl2, RT, 4h
Ru
O
R3
R1
Cl
R3
Ph2P
P
Ph2
O
R2
Au
R1 = R2 = R3 = Br (7)
R1 = H, R2 = C3H5, R3 = OMe, (9)
8
R1 = H, R2 = C3H5, R3 = OMe, ( )
Scheme 4. Ruthenium and gold complexes of 1 and 2.

100
S. Naik et al. / Polyhedron 38 (2012) 97–102
Table 1
Crystallographic data and details of structure determination of 4 and 9.
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C38H28Br6Cl6O2P2Pd
1377.10
monoclinic
P21/c
11.1542(2)
9.1213(2)
22.3965(4
90
C32H35Cl2O2PRu
654.54
orthorhombic
Pna21
28.857(12)
9.833(4)
20.884(9)
90
b (Å)
c (Å)
a
(°)
b (°)
91.020(2)
90
2278.28(8)
2
2.007
6.125
90
90
5926(4)
8
1.467
c
(°)
V (Å3)
Z
qcalc (gcmꢀ3
)
l
(Mo K
a
) (mmꢀ1
)
0.791
F(000)
1320
2688
Crystal size (mm)
T (K)
0.33 ꢂ 0.28 ꢂ 0.21
0.08 ꢂ 0.09 ꢂ 0.17
150(2)
100
2h range (°)
Total No. reflns
3.39–24.99
14719
2.0–28.5
99439
No. of independent reflections
4003 [Rint = 0.0308]
0.93
0.0302
14791[Rint = 0.073]
1.03
0.0312
S
R1
a
b
wR2
0.0420
0.0688
P
P
a
R = ||Fo| ꢀ |Fc||/ |Fo|.
P
P
2
2
wR ¼ f½ wðFo2 ꢀ F2c Þ= wðFo2Þ ꢃg1=2; w ¼ 1=½r2ðFo2Þ þ ðxPÞ ꢃ, where P ¼ ðF2oþ
b
2F2c Þ=3.
Fig. 1. Perspective view of complex
Thermal ellipsoids are drawn at the 50% probability level and all hydrogen atoms
are omitted for clarity.
4 showing the atom numbering scheme.
obtained as evinced from the 31P NMR data, which show two sing-
lets at 114.7 and 107.7 ppm corresponding to complexes 5 and 6,
respectively. The molecular structure of 4 was further confirmed
by 1H NMR, elemental analysis data and single crystal X-ray
crystallography.
The reactions of ligands 1 and 2 with one equivalent of
[AuCl(SMe2)] in dichloromethane afforded the mononuclear gold
complexes [Au{PPh2(OAr)}Cl] (Ar = 2,4,6-C6H2Br3, 7; Ar = C6H3(o-
OMe)(p-C3H5), 8) in good yield. The 31P NMR spectra of 7 and 8
show single resonances, respectively, at 121.4 and 117.0 ppm.
(g
3allyl){PPh2(OAr)}Cl] (3) in which the palladium centre retains
the allyl group as evidenced by its 1H NMR spectroscopic data.
The 31P NMR spectrum of 3 consists of a sharp singlet at
130.2 ppm. The reaction between 1 or 2 and Pd(COD)Cl2 in 2:1
molar ratio in dichloromethane afforded trans-[Pd{PPh2(OC6H2Br3-
2,4,6)}2Cl2] (4) (Scheme 2) and cis-[Pd{PPh2(OC6H3(o-OMe)
(p-C3H5)}2Cl2] (5), whose 31P NMR spectra consists of sharp singlets
at 118.5 and 114.7 ppm, respectively. Similar reaction in case of 2 in
1:1 molar ratio under refluxing conditions gave a mixture of
complexes, [Pd{PPh2(OAr)}2Cl2] (5) and [Pd2{PPh2(OAr)}2Cl4] (6)
as shown in Scheme 3. Equimolar reactions between 1 or 2 and pal-
ladium(II) precursors in THF or toluene under reflux conditions are
reported to produce chlorobridged dipalladium complexes [18],
however, when the same reaction was carried out in dichlorometh-
ane under refluxing condition, a mixture of both the mononuclear
chelate complex 5 and chloro-bridged bimetallic complex 6 were
The reaction of 2 with [Ru(
g
6-p-cym)Cl2]2 in 2:1 molar ratio in
6-p-
dichloromethane afforded the mononuclear complex [(Ru(
g
cym){PPh2(OAr)}Cl2] (9) as shown in Scheme 4. The 31P NMR spec-
trum of 9 shows a sharp singlet at 114.4 ppm. The presence of the
cymene group was confirmed from the 1H NMR spectrum which
shows a singlet at 1.37 ppm for the methyl protons. The isopropyl
3
group shows a doublet at 0.78 ppm for the CH3 proton with a JHH
Fig. 2. Perspective view of complex 9 showing the atom numbering scheme. Thermal ellipsoids are drawn at the 50% probability level and all hydrogen atoms are omitted for
clarity.

S. Naik et al. / Polyhedron 38 (2012) 97–102
101
Table 2
Selected bond distances (Å) and bond angles (°) of 4 and 9.
Bond length
Bond angle
Bond length
Bond angle
Pd1–Cl1
Pd1–Cl1i
Pd1–P1
Pd1–P1i
Br1–C2
Br2–C4
Br3–C6
P1–O1
2.287(1)
2.287(1)
2.321(1)
2.321(1)
1.887(3)
1.889(3)
1.889(3)
1.642(2)
1.807(3)
1.812(3)
1.378(3)
Cl1–Pd1–Cl1i
Cl1–Pd1–P1i
Cl1i–Pd1–P1i
Cl1–Pd1–P1
Cl1i–Pd1–P1
P1i–Pd1–P1
O1–P1–C7
O1–P1–C13
C7–P1–C13
O1–P1–Pd1
C7–P1–Pd1
C13–P1–Pd1
C1–O1–P1
O1–C1–C6
O1–C1–C2
C6–C1–C2
C3–C2–C1
C3–C2–Br1
C1–C2–Br1
180.00(3)
87.81(2)
92.19(2)
92.19(2)
87.81(2)
180.00(2)
103.35(11)
99.40(11)
103.09(12)
117.03(7)
111.39(9)
120.32(9)
125.50(16)
121.3(2)
120.1(2)
118.4(3)
121.1(2)
119.4(2)
119.4(2)
Ru1–Cl1
Ru1–Cl2
Ru1–P1
P1–O1
P1–C7
P1–C1
Ru2–Cl3
Ru2–Cl4
Ru2–P2
P2–O3
P2–C33
P2–C39
2.415(1)
2.409(1)
2.315(1)
1.638(2)
1.827(3)
1.827(3)
2.395(1)
2.415(1)
2.304(1)
1.625(2)
1.825(3)
1.833(3)
Cl1–Ru1–Cl2
Cl1–Ru1–P1
Cl2–Ru1–P1
Ru1–P1–C1
O1–P1–C1
88.30(2)
86.53(3)
91.40(3)
113.50(10)
94.72(12)
102.98(13)
122.02(10)
129.09(18)
87.38(2)
O1–P1–C7
Ru1–P1–C7
P1–O1–C13
Cl3–Ru2–Cl4
Cl3–Ru2–P2
Cl4–Ru2–P2
Ru2–P2–C33
O3–P2–C33
O3–P2–C39
Ru2–P2–C39
P2–O3–C45
P1–C7
P1–C13
O1–C1
83.01(3)
93.18(2)
125.15(10)
101.04(13)
95.11(12)
114.35(10)
127.54(19)
coupling of 6.8 Hz, while the CH proton appeared as a septet at
2.47 ppm.
romethane even under refluxing conditions. Presently we are
exploring their utility in carbon–carbon cross coupling and transfer
hydrogenation reactions.
3.1. Molecular structure of trans-[Pd{Ph2P(OAr)}Cl2] (4)
and [(Ru(g
6-p-cym){PPh2(OAr)}Cl2] (9)
Acknowledgements
We are grateful to the Department of Science and Technology
(DST), New Delhi, for financial support of this work through Grant
SR/S1/IC-17/2010. S. Naik thanks UGC, New Delhi, for Senior Re-
search Fellowship (SRF). We also thank the Department of Chemis-
try for instrumentation Facilities and National Single Crystal X-ray
Diffraction Facility, IIT Bombay and Tulane University for X-ray
structure determination.
A perspective view of the molecular structures of the complexes
4 and 9 with atom numbering scheme is shown in Figs. 1 and 2.
The details of the structure determination are described in Section
2 and the crystallographic data are given in Table 1, while the se-
lected bond lengths and bond angles are listed in Table 2. The crys-
tals suitable for the X-ray diffraction study were obtained by slow
evaporation of the solution of the complex in a mixture of dichlo-
romethane and petroleum ether. The complex 4 crystallizes in a
monoclinic system with one molecule of dichloromethane. The
molecular structure of the complex shows a square planar geome-
try around the palladium centre with the two phosphinite ligands
in a mutually trans orientation. The two Pd–Cl bonds (2.2886(7) Å)
and Pd–P bonds (2.3212(7) Å) are identical. The Cl1–Pd1–P1, Cl1i–
Pd1–P1, Cl1–Pd1–P1i, Cl1i–Pd1–P1i bond angles are 92.19(2)°,
87.81(2)°, 87.81(2)° and 92.19(2)°, respectively, which shows a
slight distortion in the square planar geometry.
Appendix A. Supplementary data
CCDC 863083 and 863084 contain the supplementary crystallo-
graphic data for 4 and 9. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
The complex 9 crystallizes in orthorhombic crystal system. The
unit cell of the crystal contains two independent molecules with al-
most similar bond parameters. The ruthenium centre has a typical
three legged piano stool tetrahedral geometry bonded to one
phosphorus and two chloride atoms along with cymene moiety.
The Ru1–Cl1 (2.4155(13) Å), Ru1–Cl2 (2.4095(13) Å) and Ru1–P1
(2.3152(13) Å) bond distances are slightly longer than the
Ru2–Cl3 (2.3953(13) Å), Ru2–Cl4 (2.4155(13) Å) and Ru2–P2
(2.3039(13) Å) in the two independent molecules. The phosphorus
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