Cationic and neutral ruthenium(II) complexes containing both arene or Cp (*) and functionalized aminophosphines. Application to hydrogenation of aromatic ketones

Article abstract of DOI:10.1016/j.jorganchem.2010.07.030

Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. For this aim, a series of novel Ru(II) complexes with the P-N-P ligands were synthesized starting from the complex [R

Full text of DOI:10.1016/j.jorganchem.2010.07.030

Journal of Organometallic Chemistry 695 (2010) 2506e2511
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Cationic and neutral ruthenium(II) complexes containing both arene or
Cp* and functionalized aminophosphines. Application to hydrogenation
of aromatic ketones
*
Murat Aydemir , Akın Baysal
Dicle University, Department of Chemistry, 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
Received 12 June 2010
Received in revised form
26 July 2010
Accepted 29 July 2010
Available online 6 August 2010
their operational simplicity. For this aim, a series of novel Ru(II) complexes with the PeNeP ligands were
synthesized starting from the complex [Ru(h m-Cl)Cl]2 or [RuCp*Cl(COD)]. The complexes
6-p-cymene)(
were fully characterized by analytical and spectroscopic methods. 31Pe{1H} NMR, DEPT,1He13C HETCOR or
1He1H COSY correlation experiments were used to confirm the spectral assignments. Complexes 5, 6 and 7
catalyze the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the
presence of iso-PrOH as the hydrogen source. Catalytic studies showed that all complexes are excellent
catalytic precursors for the transfer hydrogenation of acetophenone derivatives in 0.1 M iso-PrOH solution.
Notably 5 acts as an excellent catalyst giving the corresponding alcohols in excellent conversions up to 99%
(TOF ꢀ 492 hꢁ1).
Keywords:
Transfer hydrogenation
Ketones
Bis(phosphino)amine
Ruthenium(II) complexes
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
Transfer hydrogenation using ruthenium complexes as cata-
lysts has been an increasingly useful tool in organic synthesis
Aminophosphines and bis(phosphino)amines with PeNH and
PeNeP skeletons respectively, have proved to be much more
versatile ligands, and varying the substituents on both the P- and N-
centres gives rise the changes in the PeNeP angle and the confor-
mation around the P-centres [1e3]. Small variations in these ligands
can cause significant changes in their coordination behaviour and
the structural features of the resulting complexes [4,5]. Amino-
phosphine ligands have been studied for the last three decades and
found to be of considerable interest due their wide range of appli-
cations in organometallic chemistry for the development of indus-
trial processes involving a great number of catalytic reactions [6]. A
large number of complexes with aminophosphine ligands have been
evaluated in different catalytic reactions including allylic alkylation
[7], amination [8], Heck [9] Sonogashira [10], Suzuki [11], hydro-
formylation [12], hydrogenation [13] and polymerization [14]
reactions. Some aminophosphines and derivatives have also found
application as anticancer drugs [15], herbicides and antimicrobial
agents, as well as neuroactive agents [16].
[17e19], allowing transformations otherwise very difficult or
almost impossible to carry out. Catalytic transfer hydrogenation
with the aid of a stable hydrogen donor is a useful alternative
method for catalytic hydrogenation by molecular hydrogen
[20,21]. In transfer hydrogenation, organic molecules such as
primary and secondary alcohols [22] or formic acid and its salts
[23] have been employed as the hydrogen source. The use of the
hydrogen donor has some advantages over the use of molecular
hydrogen since it avoids no risks and the constrains associated
with hydrogen gas as well as the necessity for pressure vessels and
other equipments. 2-propanol is a popular reactive solvent for
transfer hydrogenation reactions since it is easy to handle and is
relatively non-toxic, environmentally benign and inexpensive.
The volatile acetone by-product can also be easily removed to shift
unfavourable equilibria.
We previously reported the preparation of the (PPh2)2NeC6H4-
2-CH(CH3)2,
3 and (PPh2)2NeC6H4-4-CH(CH3)2, 4 [24]. Now
we have extended our studies to include ruthenium as a central
metal [25e29]. Herein we wish to report the synthesis of Ru(II)
complexes [Ru((Ph2P)2NeC6H4-2-CH(CH3)2)(
h
6-p-cymene)Cl]Cl, 5,
[Ru((Ph2P)2NeC6H4-4-CH(CH3)2)(
h
6-p-cymene)Cl]Cl, 6 and [RuCp*
((Ph2P)2NeC6H4-4-CH(CH3)2)Cl], 7 and their application in the
* Corresponding author.
transfer hydrogenation of aromatic ketones.
E-mail address: aydemir@dicle.edu.tr (M. Aydemir).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.07.030

M. Aydemir, A. Baysal / Journal of Organometallic Chemistry 695 (2010) 2506e2511
2507
2. Results and discussion
been replaced by the bidendate chelating bis(phosphino)amine.
But, attempts to prepare [RuCp*((Ph2P)2NeC6H4-2-CH(CH3)2)Cl]
did not succeed, may be, due to the steric repulsion of the o-posi-
tion isopropyl group. In the 31Pe{1H} NMR spectra, two singlet
were observed. 1H and 13C NMR spectra of compound 7 display all
signals of coordinated ligand and are in agreement with the
structures proposed (for details see Experimental section).
Elemental analysis of product 7 is consistent with the suggested
molecular formulas.
2.1. Synthesis and characterization of the metal complexes
We have previously described [24] the synthesis of N,N-bis
(diphenylphosphino)isopropylanilines, (PPh2)2NeC6H4eCH(CH3)2,
having isopropyl substituent at the carbon 2- (3) or 4- (4) easily
prepared from the reaction of H2NeC6H4-2-CH(CH3)2, (1) or
H2NeC6H4-4-CH(CH3)2, (2) respectively, with two equivalents of
chlorodiphenylphosphine in the presence of triethylamine in thf
solution. [Ru(
h
6-p-cymene)(
m-Cl)Cl]2 which was prepared from the
2.2. Catalytic transfer hydrogenation of acetophenone derivatives
reaction of the commercially available
a
-phellandrene(5-isopropyl-
2-methylcyclohexa-1,3-diene) with RuCl3 [30] was initially chosen
The activity of Ru(II) arene complexes is well known in this
catalytic process ([39e43] and references therein). Recently, we
have reported that the complexes, based on the ligands with PeN,
PeO and PeNeP backbone, are active catalysts in the reduction of
aromatic ketones [44,45]. The observed activity of these complexes
has encouraged us to investigate other analogous ligands and other
transition metal complexes of these ligands [46,47]. So, the catalytic
activity of complexes 5, 6 and 7 in transfer hydrogenation of
aromatic ketones by iso-PrOH was investigated (Scheme 2). In all
the reactions, these complexes catalyzed the reduction of ketones
to the corresponding alcohols via hydrogen transfer from iso-PrOH.
In a typical experiment, 0.01 mmol of the complex and 1 mmol of
acetophenone were added to a solution of NaOH in iso-PrOH
(0.05 mmol of NaOH in 10 mL iso-PrOH) and refluxed at 82 ꢂC, the
reaction being monitored by GC. With a complex/NaOH ratio of 1/5,
the complexes are very active, which leads to a quantitative
as a starting material for the synthesis of ruthenium(II) complexes 5
and 6. The whole reactions carried out with [Ru(
-Cl)Cl]2 are depicted in Scheme 1.
Complexation reactions were straightforward, with coordina-
tion to ruthenium being carried out at room temperature. Treat-
ment of [Ru( -Cl)Cl]2 with one equivalent of
6-p-cymene)(
h
6-p-cymene)
(m
h
m
(PPh2)2N-C6H4-2-CH(CH3)2, (3) or (PPh2)2N-C6H4-4-CH(CH3)2, (4)
affords the corresponding mono bis(chelate) complexes in high
yield as the main products, respectively (Fig. 1). The initial color
change, i.e., from clear orange to deep red [31], attributed to the
dimer cleavage most probably by the bis(phosphino)amine ligand.
The 31Pe{1H} NMR spectra are quite consistent with the structures
[32], that of containing 5 or 6. Furthermore, 1H NMR and 13C NMR
spectral data of 5 and 6 are consistent with the structure proposed
(for details see Experimental section). 1H NMR spectra of complexes
display signals of the h
6-p-cymene ligand together with the reso-
transformation of the acetophenone, with a good TOF of <492 hꢁ1
.
nances of the hydrogens of the P-coordinated ligands. The arene
signals are well resolved and show only HeH coupling, as found in
previously reported mononuclear p-cymene compounds [33e36].
Furthermore, 13Ce{1H} NMR spectra of complexes 5 and 6 display
resonances that are consistent with a P-coordination of ligands. The
structural composition of the complex has also been confirmed by
IR and elemental analysis.
In a preliminary study, the synthesized complexes 5e7 were
evaluated as a precursor for the catalytic transfer hydrogenation of
the acetophenone by iso-PrOH/NaOH as a reducing system and the
results are summarized in Table 1. At room temperature no
appreciable formation of 1-phenylethanol was observed (Table 1,
Entries 1, 2 and 3) and also the catalytic activity of [Ru(
ene)( -Cl)Cl]2 under the applied experimental conditions is negli-
h
6-p-cym-
m
The reaction of [RuCp*Cl(COD)] with (PPh2)2N-C6H4-4-CH(CH3)2
in thf in a ratio 1:1 at r.t. for 3 h gave a red micro crystalline
precipitate of neutral complex [RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)
Cl] (7) (Scheme 1). The 31Pe{1H} NMR spectrum of 7 shows a single
resonance at 89.28 ppm, in line with the values previously observed
for similar compounds [37,38], indicating that the diene (COD) has
gible. In addition, as can be inferred from the Table 1 (Entries 4, 5
and 6), the precatalysts as well as the presence of NaOH are
necessary to observe appreciable conversions. The base facilitates
the formation of ruthenium alkoxide by abstracting proton of the
alcohol and subsequently alkoxide undergoes
b-elimination to give
ruthenium hydride, which is an active species in this reaction. This
Scheme 1. Synthesis of the [Ru((Ph2P)2N-C6H4-2-CH(CH3)2)(
(CH3)2)Cl] (7) complexes (i) 2 equiv. Ph2PCl, 2 equiv. Et3N, thf; (ii) 1 equiv. [Ru(
h
6-p-cymene)Cl]Cl (5), [Ru((Ph2P)2N-C6H4-4-CH(CH3)2)(
h
6-p-cymene)Cl]Cl, (6) and [RuCp*((Ph2P)2N-C6H4-4-CH
h
6-p-cymene)(
m-Cl)Cl]2, thf; (iv) 1 equiv. [RuCp*Cl(COD)], thf.

2508
M. Aydemir, A. Baysal / Journal of Organometallic Chemistry 695 (2010) 2506e2511
Fig. 1. The 31Pe{1H} NMR spectra of complexes: (5), [Ru((Ph2P)2N-C6H4-2-CH(CH3)2)( 6-p-cymene)Cl]Cl; (6), [Ru((Ph2P)2N-C6H4-4-CH(CH3)2)( 6-p-cymene)Cl]Cl; (7), [RuCp*
h h
((Ph2P)2N-C6H4-4-CH(CH3)2)Cl].
is the mechanism proposed by several research groups on the
studies of ruthenium catalyzed transfer hydrogenation reaction by
metal hydride intermediates [48e51]. Namely, role of the base is to
generate a more nucleophilic alkoxide ion which would rapidly
attack the ruthenium complex responsible for dehydrogenation of
iso-PrOH. As Table 1 shows, high conversions can be achieved with
the 5e7 catalytic systems. Next, performing the reaction in air or
water, slowed down the reaction but did not affect yield of the
product. In addition, we have expanded the substrate-to-catalyst
ratio to observe the effect on the catalytic efficiency. As shown in
Table 1, increasing the substrate-to-catalyst ratio does not damage
the conversions of the product in most cases except time of the
reaction lengthened. Remarkably, the transfer hydrogenation of
acetophenone could be achieved to 99% yield even when the
substrate-to-catalyst ratio reached 1000:1. Results obtained from
optimization studies indicated clearly that the excellent yields were
achieved in the reduction of acetophenone to 1-phenylethanol
when 5, 6 or 7 was used as the catalytic precursor in 15 min, 30 min
and 4 h, respectively with a substrate-catalyst molar ratio (100:1) in
iso-PrOH at 82 ꢂC (Table 1). It should be pointed out that complexes
5, 6 and 7 are more active catalysts than the corresponding
The catalytic reduction of acetophenone derivatives was all
tested with the conditions optimized for acetophenone. The reac-
tions with the [Ru((Ph2P)2NeC6H4-4-CH(CH3)2)(h
6-p-cymene)Cl]
Cl, 6 or [RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)Cl], 7 catalytic system
proceeded more slowly than that of [Ru((Ph2P)2N-C6H4-2-CH
(CH3)2)(
((Ph2P)2NeC6H4-4-CH(CH3)2)(
h
6-p-cymene)Cl]Cl, 5. It is noteworthy that the [Ru
h
6-p-cymene)Cl]Cl,
6
or [RuCp*
((Ph2P)2NeC6H4-4-CH(CH3)2)Cl], 7 display the differences in reac-
tivity (Table 1). That’s to stay, the catalytic activities in the studied
hydrogen transfer reactions were generally much higher for the [Ru
((Ph2P)2NeC6H4-4-CH(CH3)2)(h
6-p-cymene)Cl]Cl, 6 than for the
[RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)Cl], 7. For example, under the
identical conditions, transfer hydrogenation of acetophenone
derivatives with the system 6 led to 92e99% conversions within
30 min whereas with 7, the same 92e99% conversions were ach-
ieved only after 4 h period (Table 2). The encouraging catalytic
results obtained with complex 6 catalyst prompted us to investi-
gate and to change the position of the isopropyl group on the
aniline. The complex 5 has proved to be excellent catalyst precursor
in transfer hydrogenation of acetophenone derivatives, leading to
corresponding alcohols in 15 min (up to 93e99% yield). This higher
catalytic activity can be explained by the nature of the bis(amino-
phosphine) ligand which can generate an open coordination site at
precursor: [Ru(
24 h) with a 1/14 complex/NaOH ratio [52].
h m-Cl)Cl]2 (41% maximum yield in
6-p-cymene)(
Scheme 2. Hydrogen transfer from iso-PrOH to acetophenone derivatives.

M. Aydemir, A. Baysal / Journal of Organometallic Chemistry 695 (2010) 2506e2511
2509
Table 1
C]O bond so that the activity was improved giving rise to easier
hydrogenation [53e55]. The examination of the results indicates
clearly that with each of the tested complexes, the best yield was
achieved in the reduction of acetophenone derivatives when [Ru
Transfer hydrogenation of acetophenone with iso-PrOH catalyzed by [Ru
((Ph2P)2NeC6H4-2-CH(CH3)2)(h
6-p-cymene)Cl]Cl (5), [Ru((Ph2P)2NeC6H4-4-CH
(CH3)2)(
h
6-p-cymene)Cl]Cl (6) and [RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)Cl] (7).
i
Conversion (%)h
TOF(hꢁ1
)
((Ph2P)2N-C6H4-2-CH(CH3)2)(h
6-p-cymene)Cl]Cl, 5 was used as the
Entry
Catalyst
S/C/NaOH
Time
1
2
3
4
5
6
7
8
5a
6a
7a
5b
6b
7b
5c
6c
7c
5d
6d
7d
5e
6e
7e
5f
100:1:5
100:1:5
100:1:5
100:1
100:1
100:1
1 h
1 h
1 h
1 h
1 h
1 h
30 min
1.5 h
10 h
30 min
1 h
<2
<2
<2
<5
<5
<5
e
catalyst precursor. In order to investigate the evolution of the
catalyst, 5, 6 or 7, 31Pe{1H} NMR spectrum was recorded immedi-
ately after the catalytic reaction. The observed singlet at 21.6 ppm in
the spectrum corresponds to hydrolysis product diphenylphos-
phinous acid, Ph2P(O)H [56e58].
e
e
e
e
e
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
100:1:5
100:1:5
100:1:5
98 (96, 93)k
196
66
10
196
99
16
98
8
99 (95, 92)k
3. Conclusion
9
98 (95, 93)k
10
11
12
13
14
15
16
17
18
19
20
21
98
99
97
98
96
97
96
98
99
82
40
6
In conclusion, we synthesized several octahedral Ru(II)
h
6-p-cym-
6 h
1 h
complexes of formula [Ru((Ph2P)2NeC6H4-2-CH(CH3)2)(
ene)Cl]Cl, [Ru((Ph2P)2NeC6H4-4-CH(CH3)2)(
h
6-p-cymene)Cl]Cl and
12 h
12 h
2.5 h
4 h
32 h
10 min
10 min
10 min
[RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)Cl], which were fully charac-
terized. These compounds have proved to be efficient catalysts in
the transfer hydrogenation reaction (HTR) of ketones in basic iso-
8
38
25
<3
492
240
36
6f
7f
PrOH. Especially, the C6H4-2-CH(CH3)2)(h
6-p-cymene)Cl]Cl cata-
5g
6g
7g
lytic system demonstrates remarkable catalytic reactivity and in
a certain case, alcohols with up to 99% yield could be obtained even
when the substrate-to-catalyst molar ratio reached 1000:1.
Furthermore, performing the reaction in air slowed down the
reaction, but the conversion was not incredible affected in the air or
addition of water. When we increased the amount of water in the
reaction system, the high yield remained intact.
a
At room temperature; acetophenone/Ru/NaOH, 100:1:5.
b
c
d
e
f
Refluxing in iPrOH; acetophenone/Ru, 100:1, in the absence of base.
Added 0.1 mL of H2O.
Refluxing the reaction in air.
Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 500:1:5.
Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 1000:1:5.
Refluxing in iso-PrOH; acetophenone/Ru/NaOH, 100:1:5.
Determined by GC (three independent catalytic experiments).
g
h
i
4. Experimental
Referred at the reaction time indicated in column; TOF ¼ (mol product/mol Ru
(II)Cat.)xhꢁ1
.
4.1. Materials and methods
k
The amount of the water in different concentrations (0.5, 1.0 mL).
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, 2-iso-
propylaniline and 4-isopropylaniline are purchased from Fluka and
ruthenium more easily. Furthermore, complex 5 showed very high
activity for most of the ketones. 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
were used as received. [Ru(h m-Cl)Cl]2 [30] and
6-p-cymene)(
Table 2
[RuCp*Cl(COD)] [59] were prepared according to literature proce-
dures. 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 31Pe{1H} NMR spectra (162.0 MHz) were recorded
Transfer hydrogenation results for substituted acetophenones with the Catalyst
systems: [Ru((Ph2P)2N-C6H4-2-CH(CH3)2)(h
6-p-cymene)Cl]Cl (5), [Ru((Ph2P)2N-
C6H4-4-CH(CH3)2)(
h
6-p-cymene)Cl]Cl (6) and [RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)
Cl] (7).a
on a Bruker Avance 400 spectrometer, with d referenced to external
c
Entry
R
Catalyst
Time
Conv.(%)b
TOF(hꢁ1
)
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.
1
2
3
4
5
6
7
8
5
H
4-F
4-Cl
4-Br
2-MeO
4-MeO
H
4-F
4-Cl
4-Br
2-MeO
4-MeO
H
4-F
4-Cl
4-Br
2-MeO
4-MeO
15 min
15 min
15 min
15 min
15 min
15 min
30 min
30 min
30 min
30 min
30 min
30 min
4 h
96
99
97
96
94
93
97
99
98
95
93
92
97
99
99
96
94
92
384
396
388
384
376
372
194
198
196
190
186
184
24
4.2. GC analyses
6
7
GC analyses were performed on an HP 6890N Gas Chromato-
graph equipped with capillary column (5% biphenyl, 95% dime-
9
thylsiloxane) (30 m ꢃ 0.32 mm ꢃ 0.25
mm). The GC parameters
10
11
12
13
14
15
16
17
18
were for transfer hydrogenation of ketones as follows; initial
temperature, 110 ꢂC; initial time, 1 min; solvent delay, 4.48 min;
temperature ramp 80 ꢂC/min; final temperature, 200 ꢂC; final time,
21.13 min; injector port temperature, 200 ꢂC; detector temperature,
4 h
4 h
4 h
4 h
25
25
24
24
200 ꢂC, injection volume, 2.0
mL.
4 h
23
4.3. General procedure for the transfer hydrogenation of ketones
a
Catalyst (0.005 mmol), substrate (0.5 mmol), iso-PrOH (5 mL), NaOH
(0.025 mmol), 82 ꢂC, 15 min for 5, 30 min for 6 and 4 h for 7, respectively, the
concentration of acetophenone derivatives is 0.1 M.
Typical procedure for the catalytic hydrogen transfer reaction:
a solution of ruthenium complexes [Ru((Ph2P)2N-C6H4-2-CH(CH3)2)
b
Purity of compounds is checked by NMR and GC (three independent catalytic
(h h
6-p-cymene)Cl]Cl (5), [Ru((Ph2P)2N-C6H4-4-CH(CH3)2)( 6-p-
experiments), yields are based on methyl aryl ketone.
c
TOF ¼ (mol product/mol Cat.) ꢃ hꢁ1
.
cymene)Cl]Cl, (6) or [RuCp*((Ph2P)2N-C6H4-4-CH(CH3)2)Cl] (7),

2510
M. Aydemir, A. Baysal / Journal of Organometallic Chemistry 695 (2010) 2506e2511
NaOH (0.025 mmol) and the corresponding ketone (0.5 mmol) in
degassed iso-PrOH (5 mL) were refluxed for 15 min for 5, 30 min for 6
and 4 h for 7. 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.
18.96 (CH3Ph of p-cymene), ppm: assignment was based on the
1He13C HETCOR and 1He1H COSY spectra; 31P NMR (162 MHz,
CDCl3):
d
¼ 86.51 (s); IR, (KBr):
y
¼ 937 (PeNeP), 1441 (P-Ph) cmꢁ1
;
C43H45NP2RuCl2 (809.8 g/mol): calcd. C 63.78, H 5.60, N 1.73; found C
63.58, H 5.56, N 1.68.
4.4. Synthesis of ruthenium complexes
4.4.3. Synthesis of [RuCp*((Ph2P)2NeC6H4-4-CH(CH3)2)Cl] (7)
To a solution of [RuCp*Cl(COD)] (267 mg, 0.689 mmol) in 10 mL
thf, a solution (thf, 15 mL) of 4 (346 mg, 0.689 mmol) was added.
The resulting reaction mixture was allowed to proceed under stir-
ring at room temperature for 3 h. After this time, the solution was
filtered off and the solvent evaporated under vacuum, the solid
residue thus obtained was washed with diethyl ether (3 ꢃ 15 mL)
and then dried under vacuum (Scheme 1). Following recrystaliza-
tion from diethylether/CH2Cl2, a brick red crystalline was obtained
(yield 380 mg, 92.3%), m.p. 233e235 ꢂC 1H NMR (400.1 MHz,
4.4.1. Synthesis of [Ru((Ph2P)2N-C6H4-2-CH(CH3)2)(h
6-p-cymene)
Cl]Cl, (5)
To
a
solution of [Ru(h m-Cl)Cl]2 (432 mg,
6-p-cymene)(
0.685 mmol) in 10 mL thf, a solution (thf, 15 mL) of 3 (356 mg,
0.685 mmol) was added. The resulting reaction mixture was
allowed to proceed under stirring at room temperature for 1 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 recrystalization from diethylether/CH2Cl2,
a red crystalline powder was obtained (yield 510 mg, 89.2%), m.p.
CDCl3):
6.71 (d, 2H, JHeH
JHeH ¼ 8.40 Hz, H-2 and H-6), 2.65 (m, 1H, eCH(CH3)2e of aniline),
1.42 (s, 15H, hydrogens of Cp*), 1.04 (d, 6H, JHeH ¼ 6.80 Hz, eCH
(CH3)2e of aniline) ppm; 13Ce{1H} NMR (100.6 MHz, CDCl3):
d
¼ 7.13e7.47 (m, 20H, o, m and p-hydrogens of phenyls),
¼
7.60 Hz, H-3 and H-5), 6.46 (d, 2H,
284e285 ꢂC 1H NMR (400.1 MHz, CDCl3):
d
¼ 6.89e7.56 (m, 20H, o,
m, p-hydrogens of phenyls and 4H, aromatic hydrogens of aniline),
5.45 (d, 2H, 3J ¼ 5.20 Hz, aromatic hydrogens of p-cymene), 5.26 (d,
2H, 3J ¼ 5.20 Hz, aromatic hydrogens of p-cymene), 2.96 (br, 1H,
eCH(CH3)2e of aniline), 2.85 (m, 1H, eCHe of p-cymene), 2.10 (s,
3H, CH3-Ph of p-cymene), 1.22 (d, 6H, 3J ¼ 6.4 Hz, (CH3)2CHPh of p-
cymene); 0.33 (br, eCH(CH3)2e of aniline), ppm; 13Ce{1H} NMR
d
¼ 143.25 (C-1), 138.23 (C-4), 134.28 (i-carbons of phenyls), 132.18
(o-carbons of phenyls), 129.64 (p-carbons of phenyls), 127.75 (m-
carbons of phenyls), 126.08 (C-3 and C-5), 126.99 (C-2 and C-6),
90.12 (carbons Cp*), 33.33 (eCH(CH3)2e of aniline), 23.87 (eCH
(CH3)2e of aniline), 9.79 (carbons CH3-Cp*), ppm: assignment was
based on the 1He13C HETCOR and 1He1H COSY spectra; 31P NMR
(100.6 MHz, CDCl3):
d
¼ 145.25 (C-1), 140.32 (C-2), 138.21 (i-
carbons of phenyls), 135.21 (o-carbons of phenyls), 132.00 (s, p-
carbons of phenyls), 130.17 (C-4), 129.04 (C-3), 127.79 (C-5), 127.26
(m-carbons of phenyls), 125.69 (C-6), 77.78, 79.28 (aromatic
carbons of p-cymene), 96.36, 99.94 (quaternary carbons of p-
cymene), 31.09 (eCHe of p-cymene), 27.27 (eCH(CH3)2e of
aniline), 23.31 (eCH(CH3)2e of aniline), 22.26 ((CH3)2CHPh of p-
cymene), 18.94 (CH3Ph of p-cymene), ppm: assignment was based
on the 1He13C HETCOR and 1He1H COSY spectra; 31P NMR
(162 MHz, CDCl3):
d
¼ 89.28 (s); IR, (KBr):
y
¼ 938 (PeNeP), 1435
(P-Ph) cmꢁ1; C43H46NP2RuCl (775.3 g/mol): calcd. C 66.62, H 5.98, N
1.81; found C 66.48, H 5.93, N 1.78.
Acknowledgement
Partial support from Dicle University (Project number: DÜAPK
05-FF-27) is gratefully acknowledged.
(162 MHz, CDCl3):
d
¼ 90.71 (s); IR, (KBr): ¼ 945 (PeNeP),1441 (P-
y
Ph) cmꢁ1; C43H45NP2RuCl2 (809.8 g/mol): calcd. C 63.78, H 5.60, N
1.73; found C 63.61, H 5.52, N 1.69.
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Cl]Cl, (6)
h
6-p-cymene)
To
a
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d
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