Applications of transition metal complexes containing 3,3′- bis(diphenylphosphinoamine)-2,2′-bipyridine ligand to transfer hydrogenation of ketones

Article abstract of DOI:10.1016/j.jorganchem.2012.08.031

Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. 3,3′-bis(diphenylphosphinoamine)-2,2′-bipyridine, (Ph ₂PNH)₂C₁₀H₆N₂, was prepared through a single step reaction of 3,3′-diamino-2,2′- bipyridine with diphenylchlorophosphine. Reaction of (Ph₂PNH) ₂C₁₀H₆N₂ with [Ru(η⁶- benzene)(μ-Cl)Cl]₂, [Rh(μ-Cl)(cod)]₂ or [Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ gave a range of new bridged dinuclear complexes [C₁₀H₆N ₂{NHPPh₂Ru(η⁶-benzene)Cl₂} ₂], 1, [C₁₀H₆N₂{PPh ₂NHRh(cod)Cl}₂], 2 and [C₁₀H₆N ₂{NHPPh₂Ir(η⁵-C₅Me ₅)Cl₂}₂], 3, respectively. All new complexes have been fully characterized by analytical and spectroscopic methods. ¹H³¹P-{¹H} NMR, ¹H¹³C HETCOR or ¹H¹H COSY correlation experiments were used to confirm the spectral assignments. 1, 2 and 3 are suitable catalyst precursors for the transfer hydrogenation of acetophenone derivatives. Notably [Ru((Ph ₂PNH)₂C₁₀H₆N₂) (η⁶-benzene)Cl₂], 1 acts as an excellent catalyst, giving the corresponding alcohols in 98-99% yields in 10 min at 82 °C (TOF ≤600 h^-1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. This transfer hydrogenation is characterized by low reversibility under these conditions.

Full text of DOI:10.1016/j.jorganchem.2012.08.031

Journal of Organometallic Chemistry 720 (2012) 38e45
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Applications of transition metal complexes containing 3,30-
bis(diphenylphosphinoamine)-2,20-bipyridine ligand to transfer hydrogenation
of ketones
*
Murat Aydemir , Nermin Meric, Akın Baysal
Department of Chemistry, Dicle University, TR-21280 Diyarbakır, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view
of their operational simplicity. 3,30-bis(diphenylphosphinoamine)-2,20-bipyridine, (Ph2PNH)2C10H6N2,
Received 25 May 2012
Received in revised form
15 August 2012
was prepared through
chlorophosphine. Reaction of (Ph2PNH)2C10H6N2 with [Ru(
[Ir( -
5-C5Me5)( -Cl)Cl]2 gave a range of new bridged dinuclear complexes [C10H6N2{NHPPh2Ru(h6
a
single step reaction of 3,30-diamino-2,20-bipyridine with diphenyl-
h
6-benzene)(
m
-Cl)Cl]2, [Rh(
m-Cl)(cod)]2 or
Accepted 27 August 2012
h
m
benzene)Cl2}2], 1, [C10H6N2{PPh2NHRh(cod)Cl}2], 2 and [C10H6N2{NHPPh2Ir(
h
5-C5Me5)Cl2}2], 3, respec-
Keywords:
tively. All new complexes have been fully characterized by analytical and spectroscopic methods. 1H31P-
{1H} NMR, 1H13C HETCOR or 1H1H COSY correlation experiments were used to confirm the spectral
assignments. 1, 2 and 3 are suitable catalyst precursors for the transfer hydrogenation of acetophenone
Aminophosphine
Transition metal
Transfer hydrogenation
Catalyst
derivatives. Notably [Ru((Ph2PNH)2C10H6N2)(h
6-benzene)Cl2], 1 acts as an excellent catalyst, giving the
corresponding alcohols in 98e99% yields in 10 min at 82 ꢀC (TOF ꢁ600 hꢂ1) for the transfer hydroge-
nation reaction in comparison to analogous rhodium or iridium complexes. This transfer hydrogenation
is characterized by low reversibility under these conditions.
NMR
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
view of their potential utility in a variety of metal-mediated organic
transformations [12]. To date, a number of such systems with
Catalytic transfer hydrogenation with the aid of a stable
hydrogen donor is a useful alternative method for catalytic
hydrogenation by molecular hydrogen [1]. Transfer hydrogenation
of ketones by iso-PrOH is convenient in large-scale synthesis since
there is no need to employ a high hydrogen pressure or to use
hazardous reducing agents [2]. Today, the catalytic transfer
hydrogenation [3] of prochiral ketones is one of the most attractive
methods for synthesizing optically active secondary alcohols,
which form an important class of intermediates for fine chemicals
and pharmaceuticals [4,5]. There are several metal sources avail-
able that have to mediate the hydride transfer from the donor to the
substrate. Even if main-group metals like aluminum have histori-
cally been used in the transfer hydrogenation reactions [6,7],
today’s catalysts of choice are transition metal complexes
predominantly of ruthenium, rhodium [8] or iridium [9e11].
Synthesis of new aminophosphines to stabilize transition metals
in low valent states is considered to be a most challenging task in
a variety of backbone frameworks have been synthesized and their
transition metal chemistry has been explored [13]. The effect of
ligand type on structure and reactivity of transition metal
complexes is an important topic of research in coordination and
organometallic chemistry [14]. Ligands containing direct
phosphorusenitrogen bonds are quite attractive as structural
modifications can be introduced via simple PeN bond formation
[15] and they have proved to be versatile ligands, and varying the
substituents on both P- and N-centers gives rise the changes in the
PeNH angle and to conformation around the P-centers [16]. Small
variations in these ligands can cause significant changes in their
coordination behavior and the structural features of the resulting
complexes [17,18]. The use of tertiary phosphines is widespread in
organometallic chemistry and in homogeneous catalysis as these
ligands can be used to fine tune the metal reactivity and selectivity.
The complexes incorporating this ligand type are of considerable
interest because of their potential use in many processes such as
reductive elimination and oxidative addition for making and
breaking CeH bonds [19,20], formation and cleavage of NeH and
OeH bonds [21]. Also their extensive use in classical catalytic
processes such as allylic alkylation [22], Heck [23,24], Suzuki [25e
* Corresponding author. Tel.: þ90 412 248 8550; fax: þ90 412 248 8300.
E-mail address: aydemir@dicle.edu.tr (M. Aydemir).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.08.031

M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
39
27], hydrogenation [28,29], isomerization, decarbonylation, etc.
[30,31] cannot be ignored.
(Scheme 1). The 31P NMR spectrum of (Ph2PNH)2C10H6N2 showed
a single resonance at (P) 26.82 ppm, similar to those found for
d
Recently, we have reported that the novel half-sandwich
complexes, based on the ligands with PeN backbone, are active
catalysts in the reduction of aromatic ketones [32e35]. By choosing
an appropriate ligand system it is possible to fine tune the elec-
tronic and steric properties of the donor centers to bind to metals in
desired oxidation state with a specific coordination number so that
a catalyst may be generated for a specific organic transformation. In
this context, aminophosphines play a major role because of easy
and high yield synthetic methodologies and flexibility in their
reactivity toward transition metals in their various oxidation states
[36e40]. The above considerations prompted us to study the
research program on the aminophosphine complexes. We previ-
ously reported the preparation of the 3,30-bis(diphenylphosphi-
closely related compounds, indicative of both phosphorus being
equivalent as a result of the symmetry (C2 symmetry) of the
molecule (Fig. 1) [44]. 3,30-bis(diphenylphosphinoamine)-2,20-
bipyridine is unstable and decomposes rapidly on exposure to air or
moisture. When the reactions were monitored by 31P NMR spec-
troscopy, the formation of P(O)Ph2PPh2 was observed, as indicated
by signals at
d
35.20 (d) ppm and
d
ꢂ23.60 (d) ppm, {1J(PP) 228 Hz}.
Solution of (Ph2PNH)2C10H6N2 in CDCl3, prepared under anaerobic
conditions, is also unstable and decomposes gradually to give oxide
and tetraphenylbiphosphine monoxide [P(O)Ph2PPh2] derivatives.
Because the (Ph2PNH)2C10H6N2 is not stable enough in solution, the
transition metal complexes were synthesized in-situ.
The ability of dimers {[Ru(arene)(
nuclear complexes of general formula [Ru(
known [45]. Thus, the reaction of [Ru(
6-benzene)(
(Ph2PNH)2C10H6N2 gives [C10H6N2{NHPPh2Ru(
6-benzene)Cl2}2], 1
m
-Cl)Cl]2} to form mono-
6-arene)Cl2L] is well-
-Cl)Cl]2 and
noamine)-2,20-bipyridine and its [C10H6N2{NHPPh2Ru(
h
6-p-
h
cymene)Cl2}2] complex [41]. As part of our research program
we report here, the synthesis and full characterization of
three novel aminophosphine complexes [C10H6N2{NHPPh2Ru
h
m
h
in high yield, which is an air stable, red microcrystalline powder
(Scheme 1). Analysis by 31P {1H} NMR exhibits a unique signal in the
spectrum, indicative of both phosphorus being equivalent as
a result of the high symmetry of the complex. The chemical purity
of the complex 1 was confirmed by a single 31P {1H} NMR signal at
52.03 ppm (Fig. 1). This complex is highly soluble in CH2Cl2 and
slightly soluble in hexane so it can be crystallized from CH2Cl2/
hexane solution. Analysis of complex 1 by 1H NMR exhibits multi-
plet signals corresponding to the aromatic rings for 1 at 8.03e
7.40 ppm and the C6H6 protons as a singlet at 5.47 ppm. In the 1H
NMR spectrum, the NH resonance of 1 was observed as a slightly
(
h
6-benzene)Cl2}2], 1, [C10H6N2{PPh2NHRh(cod)Cl}2],
2
and
[C10H6N2{NHPPh2Ir(
h
5-C5Me5)Cl2}2], 3, and their catalytic evalua-
tion in the transfer hydrogenation of acetophenone derivatives.
2. Results and discussion
2.1. Synthesis and characterization of the complexes
Although aminolysis of chlorophosphines is an efficient method
for preparing R2PN(H)R0 or (R2P)2NR’ it has not widely been
exploited yet, in part possibly because of the associated instability
of the PeN bonds in these ligands [42,43]. Synthesis and
characterization of bis(aminophosphine) ligand with rigid back-
bone, prepared from the starting material 3,30-diamino-2,20-
bipyridine by the aminolysis method were previously reported [32]
2
doublet at 12.75 ppm (d, JNHP ¼ 10.40 Hz) due to the multiple
coupling 2JNHP which was confirmed by H/D exchange experiment.
By H/D exchange experiment the signal of the NH simply disap-
pears from the spectrum or more commonly is replaced by a weak
signal close to
d 4.80 coming from suspended droplets of HDO.
Scheme 1. Synthesis of the (Ph2PNH)2C10H6N2 ligand and its [C10H6N2{NHPPh2Ru(
complexes. (i) Cu, DMF, 110 ꢀC (ii) SnCl2, concd. HCl, ½ h; (iii) 2 equiv. Ph2PCl, 2 equiv. Et3N, thf; (iv) 1 equiv. [Ru(
equiv. [Ir( -Cl)Cl]2, thf.
5-C5Me5)(
h
6-benzene)Cl2}2], 1, [C10H6N2{PPh2NHRh(cod)Cl}2], 2 and [C10H6N2{NHPPh2Ir(
h
5-C5Me5)Cl2}2], 3
h
6-benzene)(
m
-Cl)Cl]2, thf; (vi) 1 equiv. [Rh( -Cl)(cod)]2, thf; (vii) 1
m
h
m

40
M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
Fig. 1. 31P NMR spectra of (Ph2PNH)2C10H6N2 and its complexes.
Furthermore in the 13C {1H} NMR spectrum of 1, J(31P13C) coupling
constants of the carbons of the phenyl rings were observed, which
are consistent with the literature values [46,47] (for details see
Experimental section). The structural composition of the complex 1
was further confirmed by IR spectroscopy and microanalysis, and
found to be in good agreement with the theoretical values.
2.2. Catalytic transfer hydrogenation of ketones
To the best of our knowledge Ronan Le Lagadec et al. [53] have
reported the first crystallographic determination of a bimetallic
bridged structure using this sort of ligands. Furthermore, a related
structure has been invoked by Balakrishna et al. [54] for the
formation of the ruthenium complex where the ligands also serve
as bridge between two metal centers, however no crystallographic
evidence was presented. Most recently [55] a similar structure has
been determined for a BINAP-based phosphinite ligand BINAPO,
whereas in the case for complexes 1e3, it is noted by the authors
that compounds bearing binaphtyl-based ligands bridging two
metal centers are very rare. The observed activity of these
complexes has encouraged us to investigate other analogous
ligands and other transition metal complexes of these ligands.
Furthermore, a complex with sp3-hybridized nitrogens containing
NeH bonds displays higher reaction rate. In this context,
complexes 1, 2 and 3 were selected as catalysts, iso-PrOH/NaOH as
the reducing system, and acetophenone as a model substrate
(Scheme 2) and the results are listed in Table 1.
The coordination chemistry of (Ph2PNH)2C10H6N2 with [Rh(
Cl)(cod)]2 and [Ir( -Cl)Cl]2 precursors was investigated
5-C5Me5)(
as well. Reactions of (Ph2PNH)2C10H6N2 with Rh( -Cl)(cod)]2 or
[Ir( -Cl)Cl]2 in tetrahydrofuran in a ratio of 1:1 at room
5-C5Me5)(
m-
h
m
m
h
m
temperature for 2 h gave microcrystalline precipitate of neutral
complexes 2 and 3, respectively. Complexation reactions, with
coordination to rhodium or iridium were carried out at room
temperature easily. Bridge cleavage of the dimer [Rh(m-Cl)(cod)]2
with (Ph2PNH)2C10H6N2 gave the dinuclear compound
[C10H6N2{PPh2NHRh(cod)Cl}2], 2, in good yield. The coordination of
the ligand through the P donor was confirmed by the 31P {1H} NMR
spectroscopy. The spectrum recorded in deuterated chloroform at
room temperature shows a doublet centered at d(P) 55.35 ppm with
a 1J(RhP) ¼ 163.6 Hz [48,49] (Fig. 1). IR spectroscopy and elemental
analysis of product 2 are consistent with the suggested molecular
formula. 1H and 13C NMR spectra of compound 2 display all the
signals of coordinated ligands. The 1H NMR spectrum 2 displays the
In a preliminary study, when the reaction temperature was
increased to 82 ꢀC smooth reduction of acetophenone into 1-
phenylethanol occurred, with conversion ranging from 98 to 99%
after 10 min for 1, 1 h for 2 and 3 h for 3 (Table 1, Entries 1e3). The
choice of base, such as KOH and NaOH, had little influence on the
conversions. In addition, optimization studies of the catalytic
reduction of acetophenone in 2-propanol showed that a good
activity was obtained with a base/ligand ratio of 5:1. From the
results observed, it is noteworthy that the complexes 1, 2 and 3
display the differences in reactivity. Complex 1 is the most active,
anticipated multiplets at
phenyls, broad singlets at
d
7.83e7.37 ppm for the protons of
d
5.57, 2.12 and 2.00 ppm for cod protons,
a broad multiplet at 12.65 ppm for NH. In the 13C {1H} NMR spec-
trum of compound 2, J(31P13C) coupling constants of the carbons of
the phenyl rings were observed, which are consistent with the
literature values [50] (for details see Experimental section). In the
31P {1H} NMR, a singlet at 23.38 ppm was assigned to compound
[C10H6N2{NHPPh2Ir(
h
5-C5Me5)Cl2}2], 3, in-line with the values
quantitatively converting acetophenone with a high TOF of 594 hꢂ1
It should be pointed out that complex 1 is far more active than the
corresponding precursor: [Ru( -Cl)Cl]2 (37%
6-benzene)(
.
previously observed for similar compounds [51,52]. Analysis by 1H
NMR reveals this compound to be diamagnetic, exhibiting signals
corresponding to the aromatic rings for 3 at 8.21e7.35 ppm.
Furthermore in the 13C {1H} NMR spectrum of 3, J(31P13C)
coupling constants of the carbons of the phenyl rings were
observed. The structure of the 3 was further confirmed by IR
spectroscopy and microanalysis, and found to be in good agreement
with the theoretical values (for details see Experimental section).
h
m
maximum yield in 24 h) [56]. At room temperature no appreciable
formation of 1-phenylethanol was observed (Table 1, Entries 4e6).
As can be inferred from the Table 1 (Entries 7e9) the catalysts as
well as the presence of NaOH are necessary to observe appreciable
conversions. The base facilitates the formation of alkoxide by
abstracting proton of the alcohol and subsequently alkoxide

M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
41
Scheme 2. Hydrogen transfer from iso-PrOH to acetophenone.
undergoes
b
-elimination to give ruthenium hydride, which is an
of iso-PrOH solution containing 1,
(Ketone:Ru:NaOH ¼ 100:1:5).
2
or
3
and NaOH
active species in this reaction. This is the mechanism proposed by
several workers on the studies of ruthenium catalyzed transfer
hydrogenation reaction by metal hydride intermediates [57,58]. In
addition, the replacement of the reaction atmosphere from an inert
gas to an ambient atmosphere had no negative effect on the activity
of the catalyst (Table 1, Entries 10e12). Therefore, the coupling
reactions were performed in air. Unfortunately, performing the
reaction with the addition of water slowed the reaction but did not
affect conversion of the product (Table 1, Entries 13e15). As shown
in Table 1, increasing the substrate-to-catalyst ratio do not lower
the conversions of the product in most cases except the time
lengthened. Remarkably, the transfer hydrogenation of acetophe-
none could be achieved with up to 99% conversion even when the
substrate-to-catalyst ratio reached to 1000:1 (Table 1).
As already stated, electronic properties (the nature and position)
of the substituents on the phenyl ring of the ketone caused the
changes in the reduction rate. An ortho- or para-substituted ace-
tophenone with an electron-donor substituent, i.e., 2-methoxy or
4-methoxy is reduced more slowly than acetophenone (Table 2,
Entries 4, 5, 9, 10, 14 and 15) [59]. In addition, the introduction of
electron withdrawing substituents, such as F, Cl and Br to the para-
position of the aryl ring of the ketone decreased the electron
density of the C]O bond so that the activity was improved giving
rise to easier hydrogenation [60,61]. We also carried out further
experiments to investigate the effect of bulkiness of the alky groups
on the catalytic activity and the results were given in Table 3
(entries 1e12). A variety of simple aryl alkyl ketones were trans-
formed to the corresponding secondary alcohols. It was found that
the activity is highly dependent on the steric bulk of the alkyl
group. The reactivity gradually decreased by increasing the bulki-
ness of the alkyl groups [62e65].
The catalytic reductions of acetophenone derivatives were all
tested with the conditions optimized for acetophenone and the
results are summarized in Table 2. The fourth column in Table 2
illustrates conversions of the reduction performed in a 0.1 M
Encouraged by the high catalytic activities obtained in these
preliminary studies, we next extended our investigations to include
hydrogenation of various simple ketones (Table 4). Although,
ruthenium-based catalysts have usually been applied in the
hydrogenation of simple ketones [66e68], rhodium or iridium
complexes have also been employed and found to be efficient
catalyst in several processes [69,70]. So, we investigated and
compared catalytic activity of ruthenium, rhodium and iridium
complexes of ((Ph2PNH)2C10H6N2) ligand. Investigation of catalytic
activity of these complexes has shown that they are efficient
catalysts affording almost quantitative transformation of the
ketones in short times and 1 is more active than 2 and 3 (Table 4).
For instance hydrogenations of cyclohexanone could be achieved in
Table 1
Transfer hydrogenation of acetophenone with iso-PrOH catalyzed by
[C10H6N2{NHPPh2Ru(
[C10H6N2{NHPPh2Ir(
h
h
6-benzene)Cl2}2], 1, [C10H6N2{PPh2NHRh(cod)Cl}2],
2
and
5-C5Me5)Cl2}2], 3.
k
Entry
Catalyst
S/C/NaOH
Time
Conversion (%)i
TOF (hꢂ1
)
1
2
3
4
5
6
7
8
1a
2a
3a
1b
2b
3b
1c
2c
3c
1d
2d
3d
1e
2e
3e
1f
100:1:5
100:1:5
100:1:5
100:1:5
100:1:5
100:1:5
100:1
10 min
1 h
3 h
1 h
1 h
1 h
1 h
1 h
1 h
10 min
1 h
3 h
2 h
5 h
11 h
30 min
4 h
10 h
1 h
99
99
98
trace
trace
trace
<5
<5
<5
96
99
97
98
99
98
99
98
97
594
50
33
e
e
e
e
20 min, 1.5 h and 4 h by [C10H6N2{NHPPh2Ru(
h
6-benzene)Cl2}2], 1,
100:1
100:1
e
and [C10H6N2{NHPPh2Ir(h5
-
9
e
[C10H6N2{PPh2NHRh(cod)Cl}2],
2
10
11
12
13
14
15
16
17
18
19
20
21
100:1:5
100:1:5
100:1:5
100:1:5
100:1:5
100:1:5
500:1:5
500:1:5
500:1:5
1000:1:5
1000:1:5
1000:1:5
576
99
32
49
20
<10
198
25
10
97
12
<10
C5Me5)Cl2}2], 3, respectively (Table 4, Entries 1e3). Conversion of
methyl isobutyl ketone occurred in 1 h, 3 h and 8 h by 1, 2 and 3,
respectively, while that of diethyl ketone occurred in 2 h, 5 h and
12 h by 1, 2 and 3, respectively (Table 4, Entries 7e12). Furthermore,
in order to investigate the evolution of the catalyst, 1e3, 31P {1H}
NMR spectra were recorded periodically after the catalytic reaction.
The singlet observed at 21.50 ppm at the end of third day in the
spectrum is corresponding to hydrolysis product diphenylphos-
phinous acid, Ph2P(O)H [71e73].
2f
3f
1g
2g
3g
97
98
99
8 h
16 h
a
Reaction condition: Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 100:1:5.
Reaction condition: At room temperature; acetophenone/Ru/NaOH, 100:1:5.
Reaction condition: Refluxing in iso-PrOH; acetophenone/Ru, 100:1, in the
3. Conclusions
b
c
In summary, we have synthesized a series of selected bridged
dinuclear transition metal (Ru(II), Rh(I), Ir(III)) complexes based
absence of base.
d
Reaction condition: Refluxing the reaction in air.
Reaction condition: Added 0.1 mL of H2O.
Reaction condition: Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 500:1:5.
Reaction condition: Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 1000:1:5.
3,30-bis(diphenylphosphinoamine)-2,20-bipyridine
bidendate
e
f
ligand. We have found that these complexes are efficient homo-
geneous catalytic systems that can be readily implemented and
lead to secondary alcohols from good to excellent yields. Further-
more, the Ru(II)eaminophosphine complex showed strong cata-
lytic activity in the transfer hydrogenation reaction than the
g
i
Reaction condition: Determined by GC (three independent catalytic
experiments).
k
Reaction condition: Referred at the reaction time indicated in column;
TOF ¼ (mol product/mol Ru(II)Cat.) ꢃ hꢂ1
.

42
M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
Table 2
Transfer hydrogenation results for substituted acetophenones with the catalyst systems prepared from ((Ph2PNH)2C10H6N2) and [Ru(
and [Ir(
h
6-benzene)(
m
-Cl)Cl]2, [Rh(
m-Cl)(cod)]2
h
5-C5Me5)( -Cl)Cl]2.a
m
O
OH
OH
O
Cat
R
R
+
+
c
Entry
R
Time
Conversion (%)b
TOF (hꢂ1
)
Cat: Ru(II) complex, 1
1
2
3
4
4-F
4-Cl
4-Br
2-MeO
4-MeO
5 min
5 min
10 min
20 min
15 min
99
98
98
97
95
495
490
588
291
380
5
Cat: Rh(I) complex, 2
6
7
8
9
4-F
4-Cl
4-Br
2-MeO
4-MeO
1 h
1 h
2 h
4 h
3 h
99
98
96
95
93
99
98
48
24
31
10
Cat: Ir(III) complex, 3
11
12
13
14
15
4-F
4-Cl
4-Br
2-MeO
4-MeO
1 h
1 h
3 h
5 h
4 h
98
97
96
94
92
98
97
32
19
23
a
Catalyst (0.005 mmol), substrate (0.5 mmol), iso-PrOH (5 mL), NaOH (0.025 mmol %), 82 ꢀC, respectively, the concentration of acetophenone derivatives is 0.1 M.
b
c
Purity of compounds is checked by NMR and GC (three independent catalytic experiments), yields are based on methyl aryl ketone.
TOF ¼ (mol product/mol Cat.) ꢃ hꢂ1
.
Table 3
Transfer hydrogenation results for substituted alkyl phenyl ketones with the catalyst systems prepared from ((Ph2PNH)2C10H6N2) and [Ru(
Cl)(cod)]2 and [Ir(
h
6-benzene)(
m
-Cl)Cl]2, [Rh(m-
5-C5Me5)(
m-Cl)Cl]2.
a
h
c
Entry
Catalyst
Time
Substrate
Product
Conversion (%)b
98
TOF (hꢂ1
392
)
O
OH
1
1
15 min
2
3
2
3
2 h
5 h
98
99
20
49
O
O
O
OH
OH
OH
4
1
20 min
98
294
5
6
2
3
4 h
12 h
99
98
25
<10
7
1
30 min
98
196
8
9
2
3
5 h
15 h
97
97
20
<10
10
1
1 h
98
98
11
12
2
3
12 h
24 h
98
97
<10
<10
a
Catalyst (0.005 mmol), substrate (0.5 mmol), iso-PrOH (5 mL), NaOH (0.025 mmol %), 82 ꢀC, respectively, the concentration of alkyl phenyl ketones is 0.1 M.
b
c
Purity of compounds is checked by NMR and GC (three independent catalytic experiments), yields are based on methyl aryl ketone.
TOF ¼ (mol product/mol Cat.) ꢃ hꢂ1
.

M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
43
analogous Rh(I) and Ir(III) complexes. The modular construction of
these catalysts and their flexibility toward transfer hydrogenation
4.3.2. Synthesis of [C10H6N2{PPh2NHRh(cod)Cl}2], 2
A mixture of [Rh( -Cl)(cod)]2 (90.6 mg, 0.180 mmol) and
m
make these systems to pursue.
(Ph2PNH)2C10H6N2, 1 (100 mg, 0.180 mmol) in 20 mL of tetrahy-
drofuran was stirred at room temperature for 2 h. The volume of the
solvent was then reduced to 0.5 mL before addition of diethyl ether
(10 mL). The precipitated product was filtered off and dried in vacuo
yielding 2 as a yellow microcrystalline solid (Scheme 1). Yield
166 mg, 88.1%, m.p. >200 ꢀC (dec.). 1H NMR (400.1 MHz, CDCl3)
4. Experimental
4.1. Materials and methods
Unless otherwise stated, all reactions were carried out under an
atmosphere of argon using conventional Schlenk glass-ware,
solvents were dried using established procedures and distilled
under argon immediately prior to use. Analytical grade and
deuterated solvents were purchased from Merck. PPh2Cl and 2-
chloro-3-nitropyridine are purchased from Fluka and were used
as received. The starting materials 3,30-diamino-2,20-bipyridine
d
¼ 12.65 (d, 2H, 2JNHP ¼ 10.80 Hz, NHeP), 8.04 (d, 2H, J ¼ 3.60, H-6),
7.95 (d, 2H, J ¼ 8.00, H-4), 7.83 (dd, 8H, J ¼ 4.12 and 10.12 Hz, o-
protons of phenyls), 7.47e7.37 (m, 12H, m- and p-protons of
phenyls), 6.99 (dd, 2H, J ¼ 4.80 and 6.00, H-5), 5.57 (br, 8H, CH of
cod), 2.12 (br, 8H, CH2 of cod), 2.00 (br, 8H, CH2 of cod); 13C NMR
(100.6 MHz, CDCl3):
d
¼ 28.59 (CH2 of cod), 33.01 (eCH2e), 106.79
(CH of cod), 122.23 (C-5), 126.60 (C-4), 128.37 (d, J ¼ 11.07 Hz, m-
carbons of phenyls), 130.31 (s, p-carbons of phenyls), 132.16 (d,
J ¼ 12.07 Hz, o-carbons of phenyls), 133.24 (d, J ¼ 46.60 Hz, i-
carbons of phenyls), 136.46 (C-6), 141.98 (C-2), 145.50 (C-3);
assignment was based on the 1H13C HETCOR and 1H1H COSY
[74],
[Ru(
C5Me5)(
3,30-bis(diphenylphosphinoamine)-2,20-bipyridine
6-benzene)( -Cl)(cod)]2 [77], [Ir(h5
-Cl)Cl]2 [76], Rh(
-Cl)Cl]2 [78] were prepared according to literature
[75],
h
m
m
-
m
procedures. The IR spectra were recorded on a Mattson 1000 ATI
UNICAM FT-IR spectrometer as KBr pellets. 1H (400.1 MHz), 13C
NMR (100.6 MHz) and 31P {1H} NMR spectra (162.0 MHz) were
spectra; 31P {1H} NMR (162 MHz, CDCl3):
d
¼ 55.35 (d, 1J
(
103Rh31P) ¼ 163.62 Hz); IR, (KBr):
y
¼ 905 (PeNH), 1435 (PePh),
recorded on a Bruker Avance 400 spectrometer, with
d
referenced
1582 (C]N), 3418 (NeH) cmꢂ1; C50H52N4P2Rh2Cl2 (1047.652 g/
to external TMS and 85% H3PO4 respectively. Elemental analysis
was carried out on a Fisons EA 1108 CHNS-O instrument. Melting
points were recorded by Gallenkamp Model apparatus with open
capillaries.
mol): calcd. C 57.32, H 5.00, N 5.35; found C 56.96, H 4.88, N 5.27%.
4.3.3. Synthesis of [C10H6N2{NHPPh2Ir(
A mixture of [Ir( -Cl)Cl]2 (149.4 mg, 0.180 mmol) and
5-C5Me5)(
h
5-C5Me5)Cl2}2], 3
h
m
(Ph2PNH)2C10H6N2, 1 (100 mg, 0.180 mmol) in 20 mL of tetrahy-
drofuran was stirred at room temperature for 2 h. The volume of the
solvent was then reduced to 0.5 mL before addition of diethyl ether
(10 mL). The precipitated product was filtered off and dried in vacuo
yielding 3 as an orange microcrystalline solid (Scheme 1). Yield
224 mg, 92.0%, m.p. >250 ꢀC (dec.). 1H NMR (400.1 MHz, CDCl3)
4.2. GC analyses
GC analyses were performed on a Shimadzu 2010 Plus Gas
Chromatograph equipped with capillary column (5% biphenyl, 95%
dimethylsiloxane) (30 m ꢃ 0.32 mm ꢃ 0.25
mm). The GC param-
eters for transfer hydrogenation of ketones were as follows; initial
temperature, 110 ꢀC; initial time, 1 min; solvent delay, 4.48 min;
temperature ramp 80 ꢀC/min; final temperature, 200 ꢀC; final time,
21.13 min; injector port temperature, 200 ꢀC; detector temperature,
Table 4
Transfer hydrogenation of various simple ketones with iso-PrOH catalyzed by
6-benzene)Cl2}2], 1, [C10H6N2{PPh2NHRh(cod)Cl}2],
2
and
200 ꢀC, injection volume, 2.0
mL.
[C10H6N2{NHPPh2Ru(
h
[C10H6N2{NHPPh2Ir(
h
5-C5Me5)Cl2}2], 3.a
4.3. Syntheses of transition metal complexes
Entry Catalyst
Substrate
Product
Time
Conversion (%)b
OH
O
4.3.1. Synthesis of [C10H6N2{NHPPh2Ru(
h
6-benzene)Cl2}2], 1
-Cl)Cl]2 (92.8 mg,
1
1
20 min 98
To solution of [Ru( m
a
h
6-benzene)(
0.180 mmol) in THF, a solution (THF 30 mL) of (Ph2PNH)2C10H6N2,
(100 mg, 0.180 mmol) was added. The resulting reaction mixture
was allowed to proceed under stirring at room temperature for 3 h.
After this time, the solution was filtered off and the solvent evap-
orated under vacuum, the solid residue thus obtained was washed
with diethyl ether (3 ꢃ 15 mL) and then dried under vacuum
(Scheme 1). Following recrystallization from diethylether/CH2Cl2,
a red powder was obtained (yield 170 mg, 89.4%), m.p. >200 ꢀC
2
3
2
3
1.5 h
4 h
97
98
OH
O
4
1
20 min 99
5
6
2
3
1.5 h
4 h
98
98
(dec.). 1H NMR (400.1 MHz, CDCl3)
d
¼
12.75 (d, 2H,
2JNHP ¼ 10.40 Hz, NHeP), 8.12 (d, 2H, J ¼ 4.24, H-6), 8.03 (dd, 8H,
J ¼ 8.48 and 8.64 Hz, o-protons of phenyls), 7.55e7.40 (m, 12H, m-
and p-protons of phenyls), 7.35 (d, 2H, J ¼ 8.40, H-4), 6.86 (dd, 2H,
J ¼ 4.48 and 8.40, H-5), 5.47 (d, 12H, 3J ¼ 4.8 Hz, aromatic protons of
O
OH
7
1
1 h
99
8
9
2
3
3 h
8 h
98
97
benzene), 13C NMR (100.6 MHz, CDCl3):
d
¼ 89.33 (d, 2J ¼ 3.00 Hz,
aromatic carbons of benzene), 122.81 (C-5), 127.50 (C-4), 128.40 (d,
J ¼ 10.40 Hz, m-carbons of phenyls), 130.99 (s, p-carbons of
phenyls), 132.50 (d, J ¼ 10.10 Hz, o-carbons of phenyls), 134.90 (d,
J ¼ 34.00 Hz, i-carbons of phenyls),137.54 (C-6),142.12 (C-2),148.40
(C-3); assignment was based on the 1H13C HETCOR and 1H1H COSY
O
OH
10
1
2 h
99
11
12
2
3
5 h
12 h
99
98
spectra; 31P {1H} NMR (162 MHz, CDCl3):
d
¼ 52.03 (s); IR, (KBr):
a
Reaction condition: Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 100:1:5.
Reaction condition: Determined by GC (three independent catalytic experi-
ments). Purity of compounds is checked by NMR and GC (three independent cata-
lytic experiments), yields are based on methyl aryl ketone.
y
¼ 928 (PeNH), 1435 (PePh), 1584 (C]N), 3460 (NeH) cmꢂ1
;
b
C46H40N4P2Ru2Cl4 (1054.748 g/mol): calcd. C 52.34, H 3.82, N 5.31;
found C 51.86, H 3.76, N 5.25%.

44
M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
[24] M. Aydemir, A. Baysal, G. Öztürk, B. Gümgüm, Appl. Organomet. Chem. 23
d
¼ 12.94 (d, 2H, 2JNHP ¼ 8.00 Hz, NHeP), 8.21 (dd, 8H, J ¼ 3.84 and
(2009) 108e113.
7.60 Hz, o-protons of phenyls), 8.03 (d, 2H, J ¼ 4.28, H-6), 7.86 (d,
2H, J ¼ 8.40, H-4), 7.40e7.35 (m, 12H, m- and p-protons of phenyls),
7.06 (dd, 2H, J ¼ 4.40 and 8.32, H-5), 1.36 (d, 30H, 4J ¼ 2.0 Hz, CH3 of
[25] M. Aydemir, A. Baysal, F. Durap, B. Gümgüm, S. Özkar, L.T. Yıldırım, Appl.
Organomet. Chem. 23 (2009) 467e475.
[26] M.L. Clarke, D.J. Cole-Hamilton, J.D. Woollins, J. Chem. Soc. Dalton Trans.
(2001) 2721e2723.
[27] M. Aydemir, F. Durap, A. Baysal, O. Akba, B. Gümgüm, S. Özkar, L.T. Yıldırım,
Polyhedron 28 (2009) 2313e2320.
[28] R. Spogliarich, J. Kaspar, M. Graziani, J. Organomet. Chem. 306 (1986) 407e412.
[29] A.M. Maj, M. Pietrusiewicz, I. Suisse, F. Agbossou, A. Mortreux, Tetrahedron:
Asymmetry 10 (1999) 831e835.
Cp* (C5Me5)); 13C NMR (100.6 MHz, CDCl3):
d
¼ 8.19 (C5Me5), 93.61
(C5Me5), 123.30 (C-5), 128.48 (C-4), 128.03 (d, J ¼ 10.06 Hz, m-
carbons of phenyls), 130.78 (s, p-carbons of phenyls), 132.85 (d,
J ¼ 11.07 Hz, o-carbons of phenyls), 132.00 (d, J ¼ 38.20 Hz, i-
carbons of phenyls), 136.73 (C-6), 143.41 (C-2), 146.68 (C-3),
assignment was based on the 1H13C HETCOR and 1H1H COSY
[30] P.R. Hoffman, K.G. Caulton, J. Am. Chem. Soc. 97 (1975) 4221e4228.
[31] M.S. Balakrishna, R. Panda, D.C. Smith Jr., A. Klaman, S.P. Nolan, J. Organomet.
Chem. 599 (2000) 159e165.
spectra; 31P {1H} NMR (162 MHz, CDCl3):
y
d
¼ 23.38 (s); IR, (KBr):
[32] C. Kayan, N. Meric, M. Aydemir, A. Baysal, D. Elma, B. Ak, E. Sahin, N. Gürbüz,
¼ 924 (PeNH), 1438 (PePh), 1559 (C]N), 3415 (NeH) cmꢂ1
;
_
I. Özdemir, Polyhedron 42 (2012) 142e148.
C54H58N4P2Ir2Cl4 (1351.227 g/mol): calcd. C 48.00, H 4.33, N 4.15;
found C 47.86, H 4.27, N 4.12%.
[33] M. Aydemir, A. Baysal, N. Meric, C. Kayan, B. Gümgüm, S. Özkar, E. Sahin,
J. Organomet. Chem. 696 (2011) 2584e2588.
[34] M. Aydemir, A. Baysal, N. Meric, C. Kayan, M. Togrul, B. Gümgüm, Appl.
ꢀ
Organomet. Chem. 24 (2010) 215e221.
4.3.4. General procedure for the transfer hydrogenation of ketones
[35] M. Aydemir, A. Baysal, Polyhedron 29 (2010) 1219e1224.
[36] R.J. Haines, M. Laing, E. Meintjies, P. Sommerville, J. Organomet. Chem. 215
(1981) C17eC19.
[37] M.S. Balakrishna, V.S.R. Reddy, S.S. Krishnamurthy, J.C.T.R. Burckette St
Laurent, J.F. Nixon, Coord. Chem. Rev. 129 (1994) 1e90.
[38] M.S. Balakrishna, S.S. Krishnamurthy, Inorg. Chim. Acta 230 (1995) 245e248.
[39] M.S. Balakrishna, B. Santarsiero, R.G. Cavel, Inorg. Chem. 33 (1994) 3079e
3084.
[40] M.S. Balakrishna, S.S. Krishnamurthy, R. Murugavel, M. Netaji, I.I. Mathews,
J. Chem. Soc. Dalton Trans. (1993) 477e482.
[41] M. Aydemir, A. Baysal, N. Meric, B. Gümgüm, J. Organomet. Chem. 694 (2009)
2488e2492.
[42] K.G. Gaw, M.B. Smith, A.M.Z. Slawin, New J. Chem. 24 (2000) 429e435.
[43] F. Durap, N. Biricik, B. Gümgüm, S. Özkar, W.H. Ang, Z. Fei, R. Scopelliti,
Polyhedron 27 (2008) 196e202.
[44] A.D. Burrows, M.F. Mahon, M.T. Palmer, J. Chem. Soc. Dalton Trans. (2000)
1669e1677.
Typical procedure for the catalytic hydrogen transfer reaction:
a solution of complexes [C10H6N2{NHPPh2Ru(
h
6-benzene)Cl2}2], 1,
[C10H6N2{PPh2NHRh(cod)Cl}2],
2
and [C10H6N2{NHPPh2Ir(h5
-
C5Me5)Cl2}2], 3 (0.005 mmol), NaOH (0.025 mmol) and the corre-
sponding ketone (0.5 mmol) in degassed iso-PrOH (5 mL) were
refluxed for 10 min for 1, 1 h for 2 and 3 h for 3. After this period
a sample of the reaction mixture was taken off, diluted with
acetone and analyzed immediately by GC. Conversions obtained are
related to the residual unreacted ketone.
Acknowledgements
[45] H. Le Bozec, D. Touchard, P.H. Dixneuf, Adv. Organomet. Chem. 29 (1989)
163e247.
[46] M. Aydemir, A. Baysal, N. Gürbüz, I. Özdemir, B. Gümgüm, S. Özkar, N. Çaylak,
Partial support from Dicle University (Project number: DÜAPK
05-FF-27) is gratefully acknowledged.
_
L.T. Yıldırım, Appl. Organomet. Chem. 24 (2010) 17e24.
[47] M. Hariharasarma, C.H. Lake, C.L. Watkins, G.M. Gray, J. Organomet. Chem. 580
(1999) 328e338.
[48] Q. Zhang, G. Hua, P. Bhattacharyya, A.M.Z. Slawin, J.D. Woollins, J. Chem. Soc.
Dalton Trans. (2003) 3250e3257.
[49] P. Bhattacharyya, T.Q. Ly, A.M.Z. Slawin, J.D. Woollins, Polyhedron 20 (2001)
1803e1808.
[50] F. Majoumo, P. Lönnecke, O. Kühl, E. Hey-Hawkins, Z. Anorg. Allg. Chem. 630
(2004) 305e308.
References
[1] R.A.W. Johnstone, A.H. Wilby, I.D. Entwistle, Chem. Rev. 85 (1985) 129e170.
[2] H. Jiang, Q.D. Qiao, H. Gong, Kinet. Catal. Lett. 65 (1998) 193e197.
[3] S. Gladiali, G. Mestroni, in: M. Beller, C. Bolm (Eds.), Transition Metal for
Organic Synthesis, vol. 2, Wiley-VCH, Weinheim, 1998, pp. 97e119.
[4] H. Siegel, V. Himmele, Angew. Chem. 92 (1980) 182e187.
[51] H.L. Milton, M.V. Wheatley, A.M.Z. Slawin, J.D. Woollins, Polyhedron 23 (2004)
3211e3220.
[5] C. Botteghi, S. Paganelli, A. Schionato, M. Marchetti, Chirality 3 (1991) 355e369.
[6] K. Nishide, M. Node, Chirality 14 (2002) 759e767.
[52] A.M.Z. Slawin, J. Wheatley, J.D. Woollins, Polyhedron 23 (2004) 2569e2574.
[53] R. Ceron-Camacho, V. Gomez-Benitez, R. Le Lagadec, D. Morales-Morales,
R.A. Toscano, J. Mol. Catal. A: Chem. 247 (2006) 124e129.
[54] M.S. Balakrishna, P.P. George, S.M. Mobin, Polyhedron 24 (2005) 475e480.
[55] T.J. Geldbach, A.B. Chaplin, K.D. Hanni, R. Scopelliti, P.J. Dyson, Organometal-
lics 24 (2005) 4974e4980.
[56] R. Tribo, S. Munoz, J. Pons, R. Yanez, A. Alvarez-Larena, J.F. Piniella, J. Ros,
J. Organomet. Chem. 690 (2005) 4072e4079.
[57] H. Doucet, T. Ohkuma, K. Murata, T. Yokozawa, M. Kozawa, E. Katayama,
F.A. England, T. Ikariya, R. Noyori, Angew. Chem. Int. Ed. 37 (1998)
1703e1707.
[58] H. Zhang, B.C. Yang, Y.Y. Li, Z.R. Donga, J.X. Gao, H. Nakamura, K. Murata,
T. Ikariya, Chem. Commun. (2003) 142e143.
[59] R. Guo, X. Chen, C. Elphelt, D. Song, R.H. Morris, Org. Lett. 7 (2005) 1757e1759.
[60] P. Pelagatti, M. Carcelli, F. Calbiani, C. Cassi, L. Elviri, C. Pelizzi, U. Rizzotti,
D. Rogolino, Organometallics 24 (2005) 5836e5844.
[61] J.W. Faller, A.R. Lavoie, Organometallics 20 (2001) 5245e5247.
[62] J.X. Gao, X.D. Yi, P.P. Xu, C.L. Tang, H.L. Wan, T. Ikariya, J. Organomet. Chem.
592 (1999) 290e295.
[63] J.X. Gao, H. Zhang, X.D. Yi, P.P. Xu, C.L. Tang, H.L. Wan, K.R. Tsai, T. Ikariya,
Chirality 12 (2000) 383e388.
[64] J.S. Chen, Y.Y. Li, Z.R. Dong, B.Z. Li, J.X. Gao, Tetrahedron Lett. 45 (2004)
8415e8418.
[65] Z.R. Dong, Y.Y. Li, J.S. Chen, B.Z. Li, Y. Xing, J.X. Gao, Org. Lett. 7 (6) (2005)
1043e1045.
[66] R. Noyori, T. Ohkuma, Angew. Chem. Int. Ed. 40 (2001) 40e73.
[67] J. Canivet, G. Labat, H. Stockli-Evans, G. Süss-Fink, Eur. J. Inorg. Chem. (2005)
4493e4500.
[68] P. Stepnicka, J. Ludvíc, J. Canivet, G. Süss-Fink, Inorg. Chim. Acta 359 (2006)
2369e2374.
[69] S.C. Stinson, Chem. Eng. News 77 (1999) 101e120.
[70] H.U. Blaser, F. Spindler, M. Studer, Appl. Catal. A 221 (2001) 119e143.
[71] Z. Fei, R. Scopelliti, P.J. Dyson, Inorg. Chem. 42 (2003) 2125e2130.
[72] Z. Fei, R. Scopelliti, P.J. Dyson, Eur. J. Inorg. Chem. (2004) 530e537.
[7] T. Ooi, T. Ichikawa, K. Maruoka, Angew. Chem. Int. Ed. 113 (2001) 3722e3724.
[8] Y.Y. Kuo, M.F. Haddow, A. Perez-Rodondo, G.R. Owen, J. Chem. Soc. Dalton
Trans. 39 (2010) 6239e6248.
[9] H.U. Blaser, C. Malan, B. Pugin, F. Spindler, H. Steiner, M. Studer, Adv. Synth.
Catal. 345 (2003) 103e151.
[10] T. Ikariya, K. Murata, R. Noyori, Biomol. Chem. 4 (2006) 393e406.
[11] S. Gladiali, E. Alberico, Chem. Soc. Rev. 35 (2006) 226e236.
[12] (a) L.H. Pignolet, Homogeneous Catalysis with Metal Phosphine Complexes,
Plenum Press, New York, 1983, pp. 137e165;
(b) P.W.N.M. Van Leeuwen, Organometallics 16 (1997) 3027e3037;
(c) T.J. Kwok, D.J. Wink, Organometallics 12 (1993) 1954e1959;
(d) I. Suisse, H. Bricout, A. Mortreux, Tetrahedron Lett. 35 (1994) 413e416;
(e) D. Gleich, R. Schmid, W.A. Herrmann, Organometallics 17 (1998) 2141e2143;
(f) S. Ganguly, R.M. Roundhill, Organometallics 12 (1993) 4825e4832;
(g) B. Cornils, E.G. Kuntz, J. Organomet. Chem. 502 (1995) 177e186.
[13] (a) J.T. Mague, J. Krinsky, Inorg. Chem. 40 (2001) 1962e1971;
(b) A.M.Z. Slawin, M.B. Smith, J.D. Woollins, J. Chem. Soc. Rev. (1998) 1537e1540;
(c) K.V. Katti, V.S.R. Reddy, P.R. Singh, Chem. Soc. Rev. (1995) 97e107.
[14] P.C.J. Kamer, P.W.N.M. Leeuwen, J.N.H. Reek, Acc. Chem. Res. 34 (2001) 895e904.
[15] (a) N. Biricik, C. Kayan, F. Durap, B. Gümgüm, Z. Fei, R. Scopelliti, P.J. Dyson,
_
N. Gürbüz, I. Özdemir, Inorg. Chim. Acta 363 (2010) 1039e1047;
(b) K.G. Gaw, M.B. Smith, J.W. Steed, J. Organomet. Chem. 664 (2002) 294e297.
[16] H.J. Chen, J.M. Barendt, R.C. Haltiwanger, T.G. Hill, A.D. Norman, Sulfur 26
(1986) 155e162.
[17] P. Bhattacharyya, J.D. Woollins, Polyhedron 14 (1) (1995) 3367e3388.
[18] M. Aydemir, A. Baysal, B. Gümgüm, Appl. Organomet. Chem. 693 (2008)
3810e3814.
[19] S.D. Ittel, C.A. Tolman, A.D. English, J.P. Jesson, J. Am. Chem. Soc. 100 (1978)
7577e7585.
[20] M. Antberg, L. Dahlenberg, Angew. Chem. Int. Ed. 25 (1986) 260e261.
[21] J.F.Hartwig,R.A.Anderson,R.G.Bergman, Organometallics10(1991)1710e1719.
[22] Y. Wang, X. Li, K. Ding, Tetrahedron Lett. 43 (2002) 159e161.
[23] D.P. Catsoulocas, B.R. Steele, G.A. Herapoulos, M. Micha-Screttas, C.G. Screttas,
Tetrahedron Lett. 44 (2003) 4575e4578.

M. Aydemir et al. / Journal of Organometallic Chemistry 720 (2012) 38e45
45
[73] S. Berger, S. Braun, H.O. Kolinowski, NMR-Spektroskopie von Nichtme-
tallen Band 3, 31P NMR-Spektroskopie, Georg Theime Verlag, Stuttgart,
New York, 1993.
[74] (a)S. Kanoktanaporn, J.A. Hugh-MacBride, J. Chem. Soc. Perkin1(1978) 1126e1131;
(b) L. Kaczmarek, P. Nontha-Namirski, Acta Pol. Pharm. XXXVI (1979) 629e634.
[75] A. Baysal, M. Aydemir, F. Durap, B. Gümgüm, S. Özkar, L.T. Yıldırım, Poly-
hedron 26 (2007) 3373e3378.
[76] R.A. Zelonka, M.C. Baird, J. Organomet. Chem. 35 (1972) C43eC46.
[77] G. Giordano, R.H. Crabtree, Inorg. Synth. 28 (1990) 88e90.
[78] C. White, A. Yates, P.M. Maitlis, Inorg. Synth. 29 (1992) 228e234.