Large bite bisphosphite, 2,6-C5H3N{CH2OP(-OC10H6)(μ-S)(C10H6O-)}2: Synthesis, derivatization, transition metal chemistry and application towards hydrogenation of olefi

Article abstract of DOI:10.1016/j.jorganchem.2006.12.037

Large bite bisphosphite ligand, 2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂ (2), is obtained by reacting chlorophosphite, {-OC₁₀H₆(μ-S)C₁₀

Full text of DOI:10.1016/j.jorganchem.2006.12.037

Journal of Organometallic Chemistry 692 (2007) 1683–1689
www.elsevier.com/locate/jorganchem
Large bite bisphosphite, 2,6-C5H3N{CH2OP(–OC10H6)(l-S)
(C10H6O–)}2: Synthesis, derivatization, transition metal chemistry
and application towards hydrogenation of olefins
*
Benudhar Punji, Maravanji S. Balakrishna
Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India
Received 20 October 2006; received in revised form 19 December 2006; accepted 19 December 2006
Available online 10 January 2007
Abstract
Large bite bisphosphite ligand, 2,6-C5H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2 (2), is obtained by reacting chlorophosphite,
{-OC10H6(l-S)C10H6O-}PCl (1) with 2,6-pyridinedimethanol in presence of triethylamine. Treatment of 2 with aqueous solution of
H2O2 or elemental sulfur resulted in the formation of bis(oxide) or bis(sulfide) derivatives, 2,6-C5H3N{CH2OP(E)(–OC10H6)-
(l-S)(C10H6O–)}2 (3, E = O; 4, E = S) in quantitative yield. The 10-membered cationic chelate complex, [RuCl(g6-C10H14)g2-2,6-
C5H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2-jP,jP]Cl (5) is produced in the reaction between [Ru(p-cymene)(l-Cl)(Cl)]2 and
bisphosphite 2, whereas the neutral chelate complex, cis-[Rh(CO)Cl{2,6-C5H3N{CH2OP(–OC10H6(l-S)C10H6O–)}2}-jP,jP] (6) is iso-
lated in the reaction of 2 with 0.5 equiv. of [Rh(CO)2Cl]2. Compound 2 on treatment with M(COD)Cl2 (M = Pd, Pt) produce the chelate
complexes, [MCl2{g2-2,6-C5H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2}-jP,jP] (7, M = Pd; 10, M = Pt). Similarly the reaction of bis-
phosphite 2 with Pd(COD)MeCl affords cis-[PdMe(Cl)g2-2,6-C5H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2-jP,jP] (8). Treatment of 2
with [Pd(g3-C3H5)Cl]2 in the presence of AgClO4 furnish the cationic complex, [Pd(g3-C3H5)g2-2,6-C5H3N{CH2OP(–OC10H6)-
(l-S)(C10H6O–)}2-jP,jP]ClO4 (9). The binuclear complex, [Au2Cl2{2,6-C5H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2}-jP,jP] (11) is
obtained in the reaction of compound 2 with two equiv. of AuCl(SMe2), where the ligand exhibits bridged bidentate mode of coordina-
tion. All the complexes are characterized by the 1H NMR, 31P NMR, elemental analysis and mass spectroscopy data. The cationic ruthe-
nium complex 5 is proved to be an active catalyst for the hydrogenation of styrene and a-methyl styrene.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Bisphosphite; Chalcogen derivatives; Chelate complexes; Binuclear complex; Platinum metals; Hydrogenation reactions
1. Introduction
trial and error. The bisphosphines have been extensively
used in the optimization of catalytic process and found to
be the most useful and versatile ligands for metal catalyzed
reactions. In contrast to the bisphosphines, the use of bis-
phosphites in catalysis is less extensive, though some of
them are proved to be very efficient [2]. Several bisphosph-
ite ligands have been developed by tuning their steric and
electronic properties and used for rhodium- and iridium-
catalyzed hydrogenation [3], nickel-catalyzed olefin hydro-
cyanation [4], rhodium- and platinum-catalyzed hydro-
formylation [5], rhodium-catalyzed hydrosilylation of
ketones [6] and cobalt-catalyzed Pauson–Khand reaction
[2d]. van Leeuwen et al. suggested that the large natural
bite angle in such ligands has a pronounced effect on rate
The design and synthesis of new bidentate phosphorus-
based ligand systems for transition metal catalyzed reac-
tions has become one of the most intense areas of investi-
gation. The influence of the steric and electronic
properties of these ligands on catalytic activity is well
understood, however, some other specific effects of the
ligands are yet to be rationalized [1]. This limitation made
several chemists to synthesize new ligands on the basis of
*
Corresponding author. Tel.: +91 22 2576 7181; fax: +91 22 2576 7152/
2572 3480.
E-mail address: krishna@chem.iitb.ac.in (M.S. Balakrishna).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.12.037

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B. Punji, M.S. Balakrishna / Journal of Organometallic Chemistry 692 (2007) 1683–1689
and selectivity during the catalytic reactions [1,7]. In this
context, we have designed and synthesized a large bite bis-
phosphite ligand 2 having the bulky thioether backbone
with moderate stability. As a part of our interest in organo-
metallic chemistry [8] and their catalytic investigation [9],
we report here the synthesis, chalcogen derivatives and
transition metal complexes (RuII, RhI, PdII, PtII and AuI)
of bisphosphite 2. As will be seen, the ruthenium (II) com-
plex (5) exhibits a significant catalytic activity in the hydro-
genation reaction of styrene and a-methyl styrene.
and 518.1 correspond to the ion M+ and M+ꢀ(–O,O–
P@S) fragment, respectively.
The bisphosphite ligand 2 with five potential donor
atoms (two tervalent phosphorus centers, two sulfur atoms
and a pyridinic nitrogen center) can act as 2eꢀ(g1), 4eꢀ(g2),
6eꢀ(g3), 8eꢀ(g4) or 10eꢀ(g5) donors depending upon the
metal reagents, the stoichiometry, and the reaction condi-
tions. However, it is less likely that the sulfur centers partic-
ipate in coordination due to the strong bonding interactions
between S and P atoms which makes the mesocyclic phos-
phonate rings less flexible [8a,9d]. In the present investiga-
tion due to the sterically demanding phosphorus
substituents and their preference to form cis complexes,
participation of nitrogen coordination was not anticipated.
The complexation reactions of ligand 2 was carried out with
low-valent transition metals to understand its coordination
behavior which in turn gives vital information about its cat-
alytic utility in homogeneous catalysis.
2. Results and discussion
2.1. Synthesis of ligand and its chalcogen derivatives
The chlorophosphite, 1, was synthesized previously from
the reaction of thiobis(2,20-naphthol) with an excess of PCl3
in the presence of an excess of triethylamine [9d]. Treatment
of 2,6-pyridinedimethanol with two equiv. of chlorophosph-
ite, 1, followed by the addition of triethylamine at ꢀ78 ꢁC
gives the bisphosphite, 2,6-C5H3N{CH2OP(–OC10H6)(l-S)-
(C10H6O–)}2 (2) as white crystalline solid (Scheme 1). The
31P NMR spectrum of 2 shows a single resonance at
120.7 ppm. In 1H NMR spectrum, a doublet is observed at
5.45 ppm for the methylene protons (–CH2–), because of
the coupling with phosphorus center. The mass spectrum
of compound 2 shows molecular ion peak (M+) as the base
peak at m/z 832.0. Formation of product 2 is also supported
by elemental analysis data.
2.2. Ruthenium and rhodium derivatives
The reaction of [Ru(p-cymene)(l-Cl)(Cl)]2 with an excess
of bisphosphite 2 in ethanol at 50 ꢁC afforded the cationic
complex, [RuCl(g6-C10H14)g2-2,6-C5H3N{CH2OP(–OC10-
H6)(l-S)(C10H6O–)}2-jP,jP]Cl (5) in good yield. A large
excess of bisphosphite was used to avoid the formation
of phosphite bridged bimetallic complex and the reaction
was not carried out under refluxing conditions to prevent
the loss of arene on ruthenium precursor [10]. The 31P
In order to asses the reactivity of the phosphorus (III)
centers and their steric and electronic attributes, the oxida-
tion reactions were carried out with oxidizing agents such
as hydrogen peroxide and elemental sulfur.
NMR spectrum of complex 5 shows a singlet at
1
81.4 ppm. In H NMR spectrum, a doublet is observed at
5.65 ppm for the –CH2 protons of bisphosphite, whereas
signals at 3.09 (m), 1.92 (s) and 1.25 (d) ppm confirm the
presence of p-cymene moiety. Treatment of 2 with
[Rh(CO)2Cl]2 in a 2:1 molar ratio in dichloromethane gives
the 10-membered chelate complex, cis-[Rh(CO)Cl{2,6-
C5H3N{CH2OP(–OC10H6(l-S)C10H6O–)}2}-jP,jP] (6) in
quantitative yield (Scheme 2). The IR spectrum of complex
6 exhibits a strong CO absorption at 2009 cmꢀ1 suggesting
the trans disposition of CO ligand to one of the phosphorus
centers rather than to chlorine [11]. The 13P NMR spec-
trum shows two doublet of doublets centered at 111.7
and 93.7 ppm due to the presence of two magnetically
non-equivalent phosphorus centers. The corresponding
The reaction of bisphosphite 2 with aqueous solution of
hydrogen peroxide or elemental sulfur in THF or toluene
gives the bisoxide or bissulfide derivatives, 2,6-C5H3N-
{CH2OP(E)(–OC10H6)(l-S)(C10H6O–)}2 (3, E = O;4, E =
S) in good yield. The 31P NMR spectra of 3 and 4 show sin-
1
gle resonance at ꢀ13.5 and 55.4 ppm, respectively. In H
NMR spectrum of each compound a doublet is observed
in the region 5.48–5.52 ppm for the –CH2 protons. The
mass spectrum of 3 shows a peak at m/z 864.1 (100%) cor-
responding to the molecular ion. Similarly, the mass spec-
trum of bissulfide derivative 4 shows peaks at m/z 896.1
N
N
O
O
O
P
O
O
O
O
S
P
Cl
O
O
O
ii
O
i
S
S
P
P
O
P
O
O
E
E
3 E = O
4 E = S
1
2
O
O
O
S
=
O
Scheme 1. Conditions: (i) 2,6-Pyridinedimethanol, Et3N, THF, ꢀ78 ꢁC; (ii) H2O2 or S8, toluene.

B. Punji, M.S. Balakrishna / Journal of Organometallic Chemistry 692 (2007) 1683–1689
1685
-
N
Cl
O
O
O
O
P
P
+
N
N
O
Ru
O
Cl
O
O
O
O
O
O
O
O
P
P
P
P
5
O
O
Rh
O
O
Au
Au
Cl
iii
Cl
v
CO
6
viii
iv
Cl
11
N
O
O
P
O
O
O
O
N
S
S
P
O
P
O
2
-
O
O
P
O
M
O
O
O
O
S
vi
vii
Cl
Cl
=
O
7 M = Pd
10 M = Pt
N
+
N
ClO4
O
O
O
O
O
O
O
O
P
P
P
P
O
Pd
O
Pd
O
O
Cl
Me
9
8
Scheme 2. Conditions: (iii) [Ru(p-cymene)(l-Cl)Cl]2, EtOH, 50 ꢁC; (iv) [Rh(CO)2Cl]2, toluene, r.t.; (v) Pd(COD)Cl2 or Pt(COD)Cl2, CH2Cl2, r.t.; (vi)
Pd(COD)MeCl, toluene, 70 ꢁC; (vii) [Pd(g3-C3H5)Cl]2, AgClO4, CH2Cl2, r.t.; (viii) AuCl(SMe2), CH2Cl2, r.t.
1JRhP coupling constants are 210 and 153 Hz, respectively,
C3H5)g2-2,6-C5H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2-
jP,jP]ClO4 (9) is synthesized by the treatment of 2 with 0.5
equiv. of allyl-palladium dimer, [Pd(g3-C3H5)Cl]2 in the
presence of two equiv. of AgClO4. The 31P NMR spectrum
of complex 9 shows a single resonance at 139.5 ppm. The
1H NMR spectrum and the microanalysis of complex 9
agree well with the proposed molecular composition.
2
with a JPP coupling of 38 Hz. The low field chemical shift
with large 1JRhP is assigned to P-atom trans to Cl, whereas
1
the upfield shift with comparatively low JRhP coupling
(153 Hz) is assigned to P-atom trans to carbonyl group
[11]. The mass spectrum of this complex shows a peak at
m/z 935, which corresponds to the ion [M+ꢀ (CO+Cl)].
2.3. Palladium and platinum derivatives
2.4. Gold derivative
The reactions of bisphosphite 2 with M(COD)Cl2 (M =
Pd, Pt) in dichloromethane at room temperature give the
corresponding chelate complexes, [MCl2{g2-2,6-C5H3N-
{CH2OP(–OC10H6)(l-S)(C10H6O–)}2}-jP,jP] (M = Pd,
7; M = Pt, 10) in good yield. The 31P NMR spectrum of
7 and 10 shows single resonance at 90.9 and 88.1 ppm,
The reaction of compound 2 with two equiv. of
AuCl(SMe2) in dichloromethane at room temperature
affords the binuclear complex, [Au2Cl2{2,6-C5H3N-
{CH2OP(–OC10H6)(l-S)(C10H6O–)}2}-jP,jP] (11) with
ligand exhibiting the bridged bidentate mode of coordina-
tion (Scheme 2). The 31P NMR spectrum of complex 11
shows a single resonance at 110.5 ppm and the mass spec-
trum shows a peak at m/z 1260.0 corresponding to
(M+ꢀCl) ion. Further evidence for the molecular composi-
1
respectively, with later showing a large JPtP coupling of
3227 Hz, which is consistent with the proposed cis geome-
try for similar platinum complexes [8g,8i]. In the mass spec-
trum of complex 10, a peak at m/z 1062.1 is observed for
the ion (M+ꢀCl). In order to know the preferred coordina-
tion mode of bisphosphite towards platinum metals, ligand
2 was treated with [Pd(COD)MeCl] in toluene at 70 ꢁC,
which gives the chelate complex, [PdMe(Cl)g2-2,6-C5-
H3N{CH2OP(–OC10H6)(l-S)(C10H6O–)}2-jP,jP] (8) in
quantitative yield. The 31P NMR spectrum of complex 8
shows two doublets centered at 108.3 and 69.1 ppm with
a 2JPP coupling of 57 Hz. The two doublets confirm cis-che-
lating mode of coordination of bisphosphite 2 to the palla-
dium center. The cationic chelate complex, [Pd(g3-
1
tion of complex 11 comes from elemental analysis and H
NMR data. Attempts to grow single crystals of these com-
plexes suitable for X-ray studies have been unsuccessful.
3. Catalytic activity of ruthenium complex 5
The ruthenium complex 5 is employed for the catalytic
hydrogenation of styrene and a-methyl styrene with molec-
ular hydrogen (4 atm) in THF solution at 80 ꢁC to yield
ethyl benzene and isopropyl benzene (cumene), respectively.
Catalytic studies have been performed without the addition

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B. Punji, M.S. Balakrishna / Journal of Organometallic Chemistry 692 (2007) 1683–1689
can be envisaged making it more flexible and versatile
ethyl benzene
isopropyl benzene
ligand. However, the nitrogen coordination can be antici-
pated in an octahedral complex wherein a facial isomer
can be formed if the ligand acts as a six-electron donor tri-
dentate ligand. The ruthenium complex 5 shows excellent
activity for the hydrogenation of styrene and a-methyl sty-
rene. Further coordination chemistry and the utility of this
ligand in other catalytic processes like hydroformylation of
olefins, hydrosilylation of ketones, hydrocyanation of ole-
fins is under active investigation in our laboratory.
100
80
60
40
20
0
5. Experimental
All experimental manipulations were carried out under
an atmosphere of dry nitrogen or argon using Schlenk tech-
niques. Solvents were dried and distilled prior to use by
conventional methods. Chlorophosphite, 1 was synthesized
previously from thiobis(2,20-naphthol) and PCl3 [9d]. The
metal precursors [Ru(g6-cymene)(l-Cl)Cl]2 [15], [Rh(CO)2-
Cl]2 [16], M(COD)Cl2 (M = Pd, Pt) [17], Pd(COD)MeCl
[18], [Pd(g3-C3H5)Cl]2 [19] and AuCl(SMe2) [20] were pre-
pared according to the published procedures. Other
reagents were used as obtained from commercial sources.
The 1H and 31P{1H} NMR (d in ppm) spectra were
obtained on a Varian VXR 300 or VRX 400 spectrometer
operating at frequencies of 300 or 400 and 121 or
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 shifts lie downfield of the stan-
dard in all of the cases. Infrared spectra were recorded on a
Nicolet Impact 400 FTIR instrument as a KBr disk. Micro-
analyses were carried out on a Carlo Erba (Model 1106)
elemental analyzer. Mass spectra were recorded using
Waters Q-Tof micro (YA-105) instrument. Melting points
of all compounds were determined on Veego melting point
apparatus and were uncorrected. GC analyses were per-
formed on a Perkin–Elmer Clarus 500 GC fitted with
FID detector and packed column.
1
2
3
4
5
6
7
8
9
10 11 12 13 14
time (h)
Fig. 1. The hydrogenation of styrene and a-methyl styrene using complex
5. Styrene (or a-methyl styrene):catalyst 5 = 500:1; solvent, THF (20 ml);
4 atm H2; 80 ꢁC.
of an organic base, which is usually added when the ruthe-
nium (II) complexes are used.
Using milder conditions that Bennet et al. applied with
the catalyst [RuClH(C6H6)(PPh3)] [12], we detected 96%
conversion of styrene to ethyl benzene using 0.2 mol% of
the catalyst 5 at 80 ꢁC after 10 h (Fig. 1). The hydrogena-
tion of a-methyl styrene to cumene is very slow and gives
maximum conversion of 78% even after 14 h under similar
reaction conditions. This catalyst precursor is found to be
much better than the similar catalyst [RuCl(p-cym-
ene)(PPh2Py)]+ used by Moldes et al. [13], where they
observed 94% conversion of styrene to ethyl benzene with
0.5 mol% of catalyst after 24 h. The homogeneous nature
of the catalysis was checked by the classical mercury test
[14]. Addition of a drop of mercury to the reaction mix-
tures did not affect the yields of the hydrogenations thus
showing them to be truly homogeneous systems.
4. Conclusion
A new large bite bisphosphite ligand 2 and its chalco-
genide derivatives were synthesized. The bisphosphite
ligand 2 mostly prefers chelating mode of coordination.
With rhodium (I), palladium (II) and platinum (II) deriva-
tives it forms 10-membered neutral chelated complexes,
whereas cationic chelate complexes were synthesized with
ruthenium (II) and palladium–allyl metal derivatives. Binu-
clear gold complex 11 was synthesized from the reaction of
2 with gold (I) precursor. Surprisingly, in the present inves-
tigation, the pyridyl-nitrogen coordination to the metal
centers was not observed mainly due to the bulky substitu-
ents on phosphorus centers. The ligands of the type 2 con-
taining mesocyuclic thiophosphonates are known to show
bonding interactions between P and S making the mesocy-
clic rings less flexible. As a result the sulfur atoms may not
have participated in coordination. By choosing less bulky
phosphorus substituents, the coordination of nitrogen
5.1. Synthesis of Bisphosphite 2,6-Py{CH2OP(–OC10H6-
(l-S)C10H6O–)}2 (2)
A solution of chlorophosphite 1 (1.5 g, 3.92 mmol) in
THF (20 ml) was added dropwise to a solution of 2,6-
pyridinedimethanol (0.27 g, 1.96 mmol) in THF (20 ml) at
ꢀ78 ꢁC. After 10 min of continuous stirring, Et3N
(0.59 ml, 4.31 mmol) in THF (10 ml) was added dropwise
to the reaction solution at same temperature. After the
completion of addition, the solution was warmed to room
temperature and stirred for 14 h. The solvent was removed
under reduced pressure and the white residue obtained was
dissolved in 40 ml of toluene and the triethylamine hydro-
chloride salt was removed by filtration. The clear solution
was concentrated and cooled to ꢀ25 ꢁC to give analytically
pure product of 2. Yield: 90% (1.45 g). m.p.: 134–136 ꢁC.

B. Punji, M.S. Balakrishna / Journal of Organometallic Chemistry 692 (2007) 1683–1689
1687
1
Anal. Calc. for C47H31O6NP2S2: C, 67.86; H, 3.76; N, 1.68;
S, 7.71. Found: C, 67.72; H, 3.69; N, 1.63; S, 7.65%. H
N, 1.02; S, 5.58%. H NMR (400 MHz, CDCl3): d 8.51
1
3
(d, 4H, Ar, JHH = 8.4 Hz), 7.21–7.75 (m, 3H, Py, 20H,
Ar, 4H, cymene), 5.65 (d, 4H, CH2, JPH = 9.20 Hz), 3.09
3
NMR (400 MHz, CDCl3):
d
8.72 (d, 4H, Ar,
3
3JHH = 8.0 Hz), 7.95 (t, 1H, Py, JHH = 8.0 Hz), 7.26–
7.72 (m, 2H, Py, 16H, Ar), 7.14 (d, 4H, Ar, 3JHH = 8.8 Hz),
(m, 1H, cymene), 1.92 (s, 3H, CH3), 1.25 (d, 6H,
C(CH3)2, JHH = 6.8 Hz). 31P{1H} NMR (121.4 MHz,
3
3
5.45 (d, 4H, CH2, JPH = 6.4 Hz). 31P{1H} NMR
CDCl3): d 81.4 (s).
(121.4 MHz, CDCl3): d 120.7 (s). MS (EI): m/z 832.0 (M+).
5.5. Synthesis of [Rh(CO)Cl{2,6-C5H3N{CH2OP-
(–OC10H6(l-S)C10H6O–)}2}-jP,jP] (6)
5.2. Synthesis of 2,6-C5H3N{CH2OP(O)(–OC10H6)-
(l-S)(C10H6O–)}2 (3)
A solution of [Rh(CO)2Cl]2(0.015 g, 0.038 mmol) in tol-
uene (5 ml) was added dropwise to a solution of bisphosph-
ite 2 (0.064 g, 0.077 mmol) in toluene (8 ml) and the
reaction mixture was stirred for 4 h. The resulting yellow
suspension was filtered and dried to get the pure product
5. The filtrate was also concentrated to give the same prod-
uct at ꢀ25 ꢁC. Yield: 68% (0.052 g). m.p.: 178–180 ꢁC
(dec.). Anal. Calc. for C48H31ClNO7P2S2Rh: C, 57.76; H,
3.13; N, 1.40; S, 6.42. Found: C, 57.61; H, 3.05; N, 1.38;
S, 6.33%. FT IR (KBr disk) cmꢀ1: m(CO): 2009 vs. 1H
An aqueous solution (30%) of H2O2 (0.027 ml,
0.24 mmol) in THF (5 ml) was added dropwise to a solu-
tion of bisphosphite 2 (0.1 g, 0.12 mmol) in THF (8 ml)
at room temperature. After stirring for 3 h, the solvent
was removed under vacuum. The white residual product
obtained was recrystallized from CH2Cl2/petroleum ether
mixture to give pure product 3. Yield: 83% (0.086 g).
m.p.: 148–150 ꢁC. Anal. Calc. for C47H31NO8P2S2: C,
65.35; H, 3.62; N, 1.62; S, 7.42. Found: C, 65.26; H, 3.56;
1
N, 1.60; S, 7.32%. H NMR (400 MHz, CDCl3): d 8.83
NMR (400 MHz, CDCl3):
d
8.72 (d, 4H, Ar,
(d, 4H, Ar, 3JHH = 8.8 Hz), 7.89 (t, 1H, Py,
3JHH = 8.0 Hz), 7.25–7.79 (m, 2H, Py, 16H, Ar), 7.24 (d,
4H, Ar, 3JHH = 8.0 Hz), 5.52 (d, 4H, CH2,
3JPH = 9.20 Hz). 31P{1H} NMR (162 MHz, CDCl3): d
ꢀ13.5 (s). MS (EI): m/z 864.1 (M+).
3JHH = 8.4 Hz), 7.14–7.95 (m, 3H, Py, 20H, Ar), 5.45 (d,
3
4H, CH2, JPH = 6.4 Hz). 13P{1H} NMR (121.4 MHz,
1
DMSO-d6): d 111.7 (dd, JRh–P = 210 Hz), 93.7 (dd,
1JRh–P = 153 Hz), (2JP–P = 38 Hz). MS (EI): m/z 935
(M+ꢀ(CO+Cl)).
5.3. Synthesis of 2,6-C5H3N{CH2OP(S)(–OC10H6)-
(l-S)(C10H6O–)}2 (4)
5.6. Synthesis of [PdCl2{g2-2,6-C5H3N{CH2OP(–OC10H6)
(l-S)(C10H6O–)}2}-jP,jP] (7)
A mixture of bisphosphite 2 (0.1 g, 0.12 mmol) and ele-
mental sulfur (0.008 g, 0.24 mmol) in toluene (10 ml) was
heated at 90 ꢁC for 4 h. The reaction mixture was allowed
to attain the room temperature and the solvent was
removed under vacuum. The resulted white residue was
recrystallized from CH2Cl2/petroleum ether to give the
white crystalline product 3. Yield: 78% (0.084 g). m.p.:
170–172 ꢁC. Anal. Calc. for C47H31NO6P2S4: C, 63.01; H,
3.49; N, 1.56; S, 14.32. Found: C, 62.89; H, 3.42; N, 1.49;
A solution of bisphosphite 2 (0.073 g, 0.088 mmol) in
CH2Cl2 (8 ml) was added dropwise to a solution of
Pd(COD)Cl2 (0.025 g, 0.088 mmol) in CH2Cl2(6 ml) at
room temperature and the reaction mixture was stirred
for 3 h. The precipitate formed was filtered, washed with
Et2O and dried. Yield: 66% (0.058 g). m.p.: 168 ꢁC (dec.).
Anal. Calc. for C47H31Cl2NO6P2S2Pd: C, 55.94; H, 3.09;
N, 1.39; S, 6.36. Found: C, 55.86; H, 2.99; N, 1.32; S,
6.21%. 1H NMR (400 MHz, DMSO-d6): d 8.54 (d, 4H,
1
3
S, 14.23%. H NMR (400 MHz, CDCl3): d 8.79 (d, 4H,
Ar, JHH = 8.4 Hz), 7.21–8.15 (m, 3H, Py, 20H, Ar), 5.64
3
Ar, JHH = 8.0 Hz), 7.84 (t, 1H, Py), 7.19–7.73 (m, 2H,
(br s, 4H, CH2). 31P{1H} NMR (162 MHz, DMSO-d6): d
3
Py, 20H, Ar), 5.48 (d, 4H, CH2, JPH = 9.20 Hz).
90.9 (s).
31P{1H} NMR (121.4 MHz, CDCl3): d 55.4 (s). MS (EI):
m/z 896.1 (M+), 518.1 (M+ꢀO2P(S)).
5.7. Synthesis of [PdMe(Cl){g2-2,6-C5H3N{CH2OP-
(–OC10H6) (l-S)(C10H6O–)}2}-jP,jP] (8)
5.4. Synthesis of [RuCl(g6-C10H14)g2-2,6-C5H3N{CH2OP-
(–OC10H6)(l-S)(C10H6O–)}2-jP,jP][Cl] (5)
A suspension of bisphosphite 2 (0.078 g, 0.094 mmol)
and Pd(COD)MeCl (0.025 g, 0.094 mmol) in toluene
(10 ml) was heated at 70 ꢁC for 12 h. The reaction mixture
was allowed to attain the room temperature and was fil-
tered through celite. The solvent was removed under
reduced pressure and the resulted residue was recrystallized
from CH2Cl2 and diethyl ether mixture to give crystalline
product of 8. Yield: 70% (0.065 g). m.p.:162 ꢁC (dec.).
Anal. Calc. for C48H34ClNO6P2S2Pd: C, 58.31; H, 3.47;
N, 1.42; S, 6.49. Found: C, 58.22; H, 3.39; N, 1.38; S,
6.37%. 1H NMR (400 MHz, DMSO-d6): d 8.54 (d, 4H,
A mixture of bisphosphite 2 (0.108 g, 0.13 mmol) and
[Ru(p-cymene)(l-Cl)Cl]2 (0.02 g, 0.033 mmol) in ethanol
(12 ml) was heated at 50 ꢁC for 18 h. The reaction mixture
was allowed to attain the room temperature, filtered with
celite and the volatile was removed under reduced pressure.
The resulted crude product was recrystallized in acetone to
give the pure desired product 5. Yield: 88% (0.065 g). m.p.:
134 ꢁC (dec.). Anal. Calc. for C57H45Cl2NO6P2S2Ru: C,
60.16; H, 3.99; N, 1.23; S, 5.64. Found: C, 60.01; H, 3.83;

1688
B. Punji, M.S. Balakrishna / Journal of Organometallic Chemistry 692 (2007) 1683–1689
3
3
Ar, JHH = 8.8 Hz), 7.10–8.51 (m, 3H, Py, 20H, Ar), 5.62
4H, CH2, JPH = 11.2 Hz). 31P{1H} NMR (162 MHz,
(s, 4H, CH2), 1.17 (t, 3H, CH3, JPH = 7.2 Hz). 13P{1H}
NMR (162 MHz, DMSO-d6): d 108.3 (d, JP–P = 57 Hz),
CDCl3): d 110.5 (s). MS (EI): m/z 1260.0 (M+ꢀCl).
3
2
2
69.1 (d, JP–P = 57 Hz).
5.11. Catalytic hydrogenation reactions
5.8. Synthesis of [Pd(g3-C3H5)g2-2,6-C5H3N{CH2OP-
(–OC10H6)(l-S)(C10H6O–)}2-jP,jP]ClO4 (9)
All catalytic experiments were performed in a 50 ml
stainless steel autoclave at 80 ꢁC pressurized with hydro-
gen. In a typical experiment, a solution of the catalyst pre-
cursor 5 (9.92 · 10ꢀ4 g, 8.72 · 10ꢀ4 mmol) and the organic
substrate (styrene or a-methyl styrene) (0.436 mmol) in
20 ml of THF was placed into the reactor and was sealed.
The vessel was purged three times with hydrogen and then
the autoclave was pressurized with 4 atmosphere of hydro-
gen. The reaction mixture was stirred at 80 ꢁC and the
extent of conversion was determined by periodic GC
analysis.
A solution of [Pd(g3-C3H5)Cl]2 (0.02 g, 0.055 mmol) in
CH2Cl2 (5 ml) was added dropwise to a solution of bis-
phosphite 2 (0.091 g, 0.109 mmol) in CH2Cl2 (6 ml) at
room temperature. After 2 h, AgClO4 (0.025 g,
0.109 mmol) was added and the reaction mixture was stir-
red for additional 30 min. The suspension was filtered
through celite to separate AgCl salt. The solution obtained
was concentrated to 2 ml and layered with petroleum ether,
which gives yellow crystalline product of 9. Yield: 75%
(0.089 g). m.p.: 184 ꢁC (dec.). Anal. Calc. for
C50H36ClNO10P2S2Pd: C, 55.67; H, 3.36; N, 1.29; S, 5.94.
Acknowledgements
1
Found: C, 55.62; H, 3.31; N, 1.25; S, 5.88%. H NMR
We are grateful to the Department of Science and Tech-
nology (DST), New Delhi for funding through Grant SR/
S1/IC-05/2003. B.P. thanks CSIR for Senior Research Fel-
lowship (SRF). We also thank SAIF, Mumbai, Depart-
ment of Chemistry Instrumentation Facilities, Bombay,
for spectral and analytical data.
3
(400 MHz, CDCl3): d 8.52 (d, 4H, Ar, JHH = 8.8 Hz),
7.22–7.75 (m, 3H, Py, 12H, Ar), 7.18 (d, 8H, Ar,
3JHH = 8.8 Hz), 5.63 (s, 4H, CH2), 5.14–5.27 (m, 1H, allyl),
4.84 (br s, 2H, allyl), 4.04 (br s, 2H, allyl). 31P{1H} NMR
(162 MHz, CDCl3): d 139.5 (s).
5.9. Synthesis of [PtCl2{g2-2,6-C5H3N{CH2OP-
(–OC10H6)(l-S)(C10H6O–)}2}-jP,jP] (10)
Appendix A. Supplementary material
Important spectroscopic data of compounds 2–4, 6, 8,
10 and 11. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2006.12.037.
A solution of bisphosphite 2 (0.058 g, 0.07 mmol) in
CH2Cl2 (8 ml) was added dropwise to a solution of
Pt(COD)Cl2 (0.025 g, 0.067 mmol) in CH2Cl2(6 ml) at
room temperature and stirred for 3 h. The white precipi-
tate formed was filtered and was dried under vacuum to
the desired product. Yield: 66% (0.048 g). m.p.: 186 ꢁC
(dec). Anal. Calc. for C47H31Cl2NO6P2S2Pt: C, 51.42; H,
2.85; N, 1.27; S, 5.84. Found: C, 51.36; H, 2.56; N, 1.23;
S, 5.59%. 1H NMR (400 MHz, DMSO-d6): d 8.52 (d,
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