Arene ruthenium oxinato complexes: Synthesis, molecular structure and catalytic activity for the hydrogenation of carbon dioxide in aqueous solution

Article abstract of DOI:10.1016/j.jorganchem.2009.09.008

Two families of arene ruthenium oxinato complexes of the types [(η⁶-arene)Ru(η²-N,O-L)Cl] and [(η⁶-arene)Ru(η²-N,O-L)(OH₂)]⁺ have been synthesized from the dinuclear precursors [(η⁶

Full text of DOI:10.1016/j.jorganchem.2009.09.008

Journal of Organometallic Chemistry 694 (2009) 3973–3981
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Communication
Arene ruthenium oxinato complexes: Synthesis, molecular structure
and catalytic activity for the hydrogenation of carbon dioxide
in aqueous solution
*
Trieu-Tien Thai, Bruno Therrien, Georg Süss-Fink
Institut de Chimie, Université de Neuchâtel, Case postale 158, CH-2009 Neuchâtel, Switzerland
a r t i c l e i n f o
a b s t r a c t
Two families of arene ruthenium oxinato complexes of the types [(g g
6-arene)Ru(
[(g g g
(arene = para-cymeme or hexamethylbenzene) and the corresponding oxine LH (LH = 8-hydroxyquino-
line, 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5-nitro-8-hydroxyquinoline,
5,7-dimethyl-8-hydroxyquinoline, 5,7-dichloro-2-methyl-8-hydroxyquinoline). The molecular struc-
2-N,O-L)Cl] and
Article history:
Received 14 July 2009
Received in revised form 21 August 2009
Accepted 3 September 2009
Available online 12 September 2009
6-arene)Ru( 2-N,O-L)(OH2)]+ have been synthesized from the dinuclear precursors [( 6-arene)RuCl2]2
tures of the neutral chloro complexes [(
5,7-dichloro-2-methyl-8-hydroxyquinoline) and [(
g
6-C6Me6)Ru(
g
g
2-N,O-L)Cl] (LH = 8-hydroxyquinoline,
2-N,O-L)Cl] (LH = 5,7-dichloro-2-
6-MeC6H4Pri)Ru(g2
Keywords:
Ruthenium
Arene
Oxinato
Hydrogenation
Carbon dioxide
6-MeC6H4Pri)Ru(
g
methyl-8-hydroxyquinoline) as well as those of the cationic aqua derivatives [(
g
-
N,O-L)(OH2)]+ (LH = 8-hydroxyquinoline, 5,7-dimethyl-8-hydroxyquinoline), isolated as the tetrafluoro-
borate salts, show in all cases a piano-stool arrangement with the arene ligand, the chelating oxinato
ligand and the chloro or the aqua ligand surrounding the ruthenium center in a pseudo-tetrahedral fash-
ion. The analogous reaction of [(
dinemethanol or tetrahydrofurfurylamine did not give the expected analogs but resulted in the
formation of the complexes [(
6-MeC6H4Pri)Ru( 2-NC5H4CH2OH)Cl]+ and [( 6-MeC6H4Pri)Ru(g1
NHCH2C4H3O)Cl2]. The neutral and cationic complexes of the types [(
6-arene)Ru( 2-N,O-L)Cl] and
[(
6-arene)Ru( 2-N,O-L)(OH2)]+ have been found to catalyze the hydrogenation of carbon dioxide to give
formate in alkaline aqueous solution with catalytic turnovers up to 400.
Ó 2009 Elsevier B.V. All rights reserved.
g
6-MeC6H4Pri)RuCl2]2 with other N,O-chelating ligands such as 2-pyri-
g
g
g
-
g
g
g
g
1. Introduction
as far as water-soluble catalysts for transfer hydrogenation reac-
tions in aqueous solution are concerned [11–21].
The first arene ruthenium complex was obtained from the reac-
The hydrogenation of carbon dioxide to give formic acid in
aqueous solution is an attractive approach to the use of carbon
dioxide as an economical and ecological C1 source [22]. This reac-
tion, first reported in 1976 by Inoue and co-workers, is catalyzed
by various group VIII metal phosphine complexes in benzene in
the presence of water and base [23]. The direct formation of formic
acid from CO2 and H2 in supercritical carbon dioxide using ruthe-
nium catalysts was pioneered by Noyori and Jessop [24–28], while
the hydrogenation of carbon dioxide in water, catalyzed by water-
soluble rhodium or ruthenium complexes was developed by Gass-
ner and Leitner [29] and by Joó and Laurenczy [30–33]. Himeda
carefully studied the influence of the pH on this reaction and de-
signed rhodium, iridium and ruthenium complexes containing
chelating N,N-ligands that can be deprotonated and that are highly
active in basic solution [34]. The aqueous hydrogenation of carbon
dioxide under acidic conditions, catalyzed by water-soluble arene
ruthenium or pentamethylcyclopentadienyl iridium complexes,
was pioneered by Ogo and Fukuzumi [35–37].
tion of RuCl3ꢀnH2O with 1,3-cyclohexadiene and reported by Wink-
haus and Singer in 1967 as a polymeric material, [(g
6-C6H6)RuCl2]n
[1]. Later studies by Zelonka and Baird [2] and by Bennett and
Smith [3] showed this complex to be a dimer, [(
g
6-C6H6)RuCl2]2.
Since these early reports, the chemistry of arene ruthenium com-
plexes has been steadily developed [4,5]. A new impetus came into
this field in 1988, when Ludi, Merbach, Bürgi and co-workers
showed that arene ruthenium aqua complexes previously observed
by NMR spectroscopy [2] can be isolated under certain conditions;
the characterization of the cation [(g
6-C6H6)Ru(H2O)3]2+ by single-
crystal X-ray structure analysis of the sulfate salt can be considered
as a breakthrough [6]. In the 1990s we found that the chloride or
tetrafluoroborate salts of cationic arene ruthenium complexes are
well soluble in water, the arene ruthenium bond being robust to-
ward hydrolysis [7–9], which resulted in a rapid development of
arene ruthenium chemistry in aqueous solution [10], especially
Based on our work on water-soluble organometallic complexes
containing chelating ligands for catalytic transfer hydrogenation
* Corresponding author. Tel.: +41 32 718 2405; fax: +41 32 718 2511.
E-mail address: georg.suess-fink@unine.ch (G. Süss-Fink).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.09.008

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T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
reactions using sodium formate and water as hydrogen source [11–
12], we intended to develop a complementary catalyst for the hydro-
genation of CO2 to give HCOOꢁ, which can be coupled to the NADH-
sponding cationic aqua complexes [11,12,39], the hydrolysis of the
chloro complexes 1–11 does not give the expected aqua com-
plexes. We therefore prepared these cationic complexes by react-
regenerating (
g
5-C5Me5)Rh(ortho-phenanthroline) catalyst for the
ing the triaqua complexes [(g
6-arene)Ru(OH2)3]2+ in aqueous
chemoenzymatic enantioselective reduction of ketones (Scheme
solution with the corresponding 8-hydroxyquinoline derivatives.
1), catalyst using formate as a hydrogen source to give carbon diox-
[(η6-arene)Ru(OH2)3]2+ LH
ide [13]. We decided to synthesize and to test (g
6-arene)Ru(oxinato)
+
complexes for this purpose. The first arene ruthenium complexes
containing oxinato ligands have been synthesized by Kirchner and
co-workers, who structurally characterized the para-cymene com-
[(η6-arene)Ru(η2-N,O-L)(OH2)]+ H O H3O+
+
+
2
plex [(g g
6-MeC6H4Pri)Ru( 2-N,O-L)Cl] (LH = 8-hydroxyquinoline)
(1) [38]. In this paper we report the synthesis of a whole series of
para-cymene ruthenium chloro complexes containing substituted
oxinato ligands, the hexamethylbenzene analogs, the corresponding
cationic aqua complexes and their catalytic properties for the hydro-
genation of carbon dioxide in aqueous solution.
+
+
Ru
N
Ru
N
OH2
R1
OH2
O
O
R3
R3
R1
2. Results and discussion
2.1. Synthesis of the chloro complexes [(g g
6-arene)Ru( 2-N,O-L)Cl]
(2–11)
R2
R2
12 R1 = H, R2 = H, R3 = H
16 R1 = H, R2 = H, R3 = H
The para-cymene ruthenium complex [(g
6-MeC6H4Pri)RuCl2]2
13
17
R1 = Me, R2 =Cl, R3 = Cl
R1 = Me, R2 = Cl, R3 = Cl
reacts in tetrahydrofuran solution at room temperature with
potassium 8-hydroxyquinolate to give the known [38] 8-hydrox-
yquinolinato complex 1. This reaction reported by Kirchner and
co-workers [38] also works with various substituted 8-hydroxy-
quinolates. However, for the analogous reactions of the hexameth-
14 R1 = H, R2 = Cl, R3 = H
15 R1 = H, R2 = Me, R3 = Me
18 R1 = H, R2 = NO2, R3 = H
19 R1 = H, R2 = Me, R3 = Me
The cationic complexes 12–19 can be isolated as the tetrafluorobo-
rate salts that form air-stable orange-red solids, well soluble in
water, methanol and acetonitrile. The spectroscopic (MS, 1H and
13C NMR) and analytical data are given in Section 3.
ylbenzene precursors [(g
6-C6Me6)RuCl2]2 chloroform has to be
used as solvent for solubility reasons.
η6
[( -arene)RuCl2]2
2 KL
+
[(η6-arene)Ru(η2-N,O-L)Cl]
2.3. Molecular structures of the complexes [(
Ru(
2-N,O-L)Cl] (5), [( 6-C6Me6)Ru( 2-N,O-L)Cl] (6, 11) and
[(
6-MeC6H4Pri)Ru( 2-N,O-L)(OH2)]+ (12, 15)
g
6-MeC6H4Pri)
2 KCl
+
g
g
g
g
g
The para-cymene chloro complex 5 crystallizes in the mono-
clinic centrosymmetric space group P21/n. The asymmetric unit
comprises only one molecule, the molecular structure of which is
depicted in Fig. 1. Crystallographic details are given in Table 8,
and significant bond lengths and bond angles are listed in Table
1. The hexamethylbenzene chloro complex 6 crystallizes also in
the monoclinic centrosymmetric space group P21/c, the asymmet-
ric unit comprising only one molecule. The molecular structure of 6
is depicted in Fig. 2, crystallographic details are given in Table 8,
and significant bond lengths and bond angles are listed in Table
2. The 5,7-dichloro-2-methyl-substituted analog 11 crystallizes in
the monoclinic centrosymmetric space group P21/a, the asymmet-
ric unit comprising only one molecule. The molecular structure of
11 is depicted in Fig. 3, crystallographic details are given in Table 8,
and significant bond lengths and bond angles are listed in Table 3.
In the chloro complexes 5, 6 and 11, the ruthenium atom is coordi-
Ru
Ru
Cl
R1
Cl
R1
O
O
R3
N
R3
N
R2
R2
6
7
1
R1 = H, R2 = H, R3 = H
R1 = H, R2 = Cl, R3 = Cl
R1 = H, R2 = H, R3 = H [38]
2 R1 = H, R2 = Cl, R3 = Cl
3 R1 = H, R2 = Cl, R3 = H
8 R1 = H, R2 = Cl, R3 = H
9
10
4
R1 = H, R2 = NO2, R3 = H
R1 = H, R2 = Me, R3 = Me
R1 = H, R2 = NO2, R3 = H
5 R1 = Me, R2 = Cl, R3 = Cl
11 R1 = Me, R2 = Cl, R3 = Cl
nated to the
atom of the
g
g
6-arene ligand, to the oxygen atom and the nitrogen
2-oxinato ligand, as well as to the chlorine atom, the
All chloro complexes 1–11 have been isolated by precipitation with
diethyl ether and purified by column chromatography on silica gel,
they form air-stable, orange to red crystalline solids which are well
soluble in dichloromethane, chloroform and acetone. The spectro-
scopic (MS, 1H and 13C NMR) and analytical data are given in Sec-
tion 3.
coordination geometry of ruthenium center being pseudo-tetrahe-
dral. The Ru–N and Ru–O distances are similar to those found in 1
[38].
The tetrafluoroborate salt of the aqua complex 12 crystallizes in
the orthorhombic centrosymmetric space group Pcab. The asym-
metric unit comprises one molecule of the cationic complex and
one tetrafluoroborate counter-anion. The molecular structure of
12 is depicted in Fig. 4. Crystallographic details are given in Table
8, and significant bond lengths and bond angles are listed in Table
4. The 5,7-dimethyl-substituted analog 15[BF4] crystallizes in the
2.2. Synthesis of the aqua complexes [(g g
6-arene)Ru( 2-N,O-L)(OH2)]+
(12–19)
In contrast to arene ruthenium chloro complexes containing
chelating N,N-ligands, which hydrolyze in water to give the corre-
ꢀ
triclinic centrosymmetric space group P1. The asymmetric unit

T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
3975
+
+
CO2 + Cl-
HCOO-
H2
H3O+
Rh
N
Ru
N
Cl
N
O
OH2
H2O
H2O
+
OH
NAD+
Rh
R1
R2
Ru
N
H
H3O+
CO2
N
O
H
N
H2O
alcohol
OH-
dehydrogenase
H2O
2+
O
Ru
N
HCOO-
Rh
N
O
OH
NADH
R1
R2
N
H2
OH2
Scheme 1. Coupling of CO2-hydrogenating catalyst system to the CO2-evolving catalyst system in the catalytic regeneration of NADH [13].
comprises four cationic complexes, four tetrafluoroborate counter-
anions and a water molecule. The molecular structure of 15 is de-
picted in Fig. 5, crystallographic details are given in Table 8, and
significant bond lengths and bond angles are listed in Table 5. In
both cationic aqua complexes 12 and 15, the ruthenium atom is
coordinated to the
the nitrogen atom of the
g
6-MeC6H4Pri ligand, to the oxygen atom and
2-oxinato ligand, as well as to the oxy-
g
gen atom of a water ligand, the coordination geometry of ruthe-
nium being pseudo-tetrahedral. The Ru–N and Ru–O distances
are also similar to those found in 1 [38].
2.4. Catalytic application of the g
2-oxinato complexes for the
hydrogenation of carbon dioxide in aqueous solution
Based on the studies of Himeda [34], Ogo and Fukuzumi [35–
37] on the use of the water-soluble arene ruthenium complexes
containing bipyridine (bipy) as ligand for the hydrogenation of car-
bon dioxide to give formic acid in aqueous solution, we checked
the catalytic potential of the
g
2-oxinato complexes 1, 4, 9, 10
and 12[BF4] for this reaction. They do indeed catalyze this reaction
in alkaline aqueous solution to give formate, the highest activity
being observed for 12[BF4] (Table 6).
CO2 þ H2 ! HCOOH
The pH dependence of the catalytic activity of 12[BF4] was stud-
ied for the hydrogenation of carbon dioxide to give formic acid. Un-
der acidic conditions, the reaction does not work, the catalytic
activity is maximal for pH 14 (Table 7). The temperature depen-
dence of the catalytic activity of 12[BF4] was also studied: the max-
imum turnover was obtained at 100 °C (Fig. 6). The kinetic plot
shows that under these conditions the reaction is almost complete
after 10 h when formic acid starts to decompose. The maximum
turnover frequency (97 hꢁ1) was observed after 2 h (Fig. 7).
In accordance with observations by Ogo and Fukuzumi for
Fig. 1. Molecular structure of 5.
Table 1
Selected bond lengths (Å) and angles (°) in 5.
(g
6-arene)Ru(bipyridine) complexes [35,36], we believe the cata-
lytic cycle for carbon dioxide hydrogenation by (
6-arene)Ru(oxi-
Interatomic distances
Bond angles
Ru(1)–Cl(1)
Ru(1)–N(1)
Ru(1)–O(1)
Ru(1)–C(11)
Ru(1)–C(12)
Ru(1)–C(13)
Ru(1)–C(14)
Ru(1)–C(15)
Ru(1)-C(16)
2.4130(6)
2.1455(17)
2.0633(14)
2.175(2)
2.172(2)
2.185(2)
2.215(2)
2.203(2)
2.164(2)
N(1)–Ru(1)–O(1)
N(1)–Ru(1)–Cl(1)
O(1)–Ru(1)–Cl(1)
78.55(6)
82.42(5)
87.85(4)
g
nato) complexes to involve a hydrido complex formed in situ from
the corresponding aqua or chloro complexes (Scheme 2). The
hydrido complex may insert CO2 to give the corresponding formyl
complex, which will then react with hydroxide to give the for-
mate anion and a hydroxo complex that can be converted with
molecular hydrogen into the catalytically active hydrido complex,
see Scheme 2.

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T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
Fig. 3. Molecular structure of 11.
Fig. 2. Molecular structure of 6.
Table 3
Selected bond lengths (Å) and angles (°) in 11.
Table 2
Interatomic distances
Bond angles
Selected bond lengths (Å) and angles (°) in 6.
Ru(1)–Cl(1)
Ru(1)–N(1)
Ru(1)–O(1)
Ru(1)–C(11)
Ru(1)–C(12)
Ru(1)–C(13)
Ru(1)–C(14)
Ru(1)–C(15)
Ru(1)–C(16)
2.4055(11)
2.139(3)
2.099(3)
2.182(4)
2.246(4)
2.216(4)
2.189(4)
2.197(4)
2.189(4)
N(1)–Ru(1)–O(1)
N(1)–Ru(1)–Cl(1)
O(1)–Ru(1)–Cl(1)
76.82(10)
87.40(8)
89.52(8)
Interatomic distances
Bond angles
Ru(1)–Cl(1)
Ru(1)–N(1)
Ru(1)–O(1)
Ru(1)–C(10)
Ru(1)–C(11)
Ru(1)–C(12)
Ru(1)–C(13)
Ru(1)–C(14)
Ru(1)–C(15)
2.4108(13)
2.088(5)
2.107(4)
2.190(5)
2.214(5)
2.210(4)
2.226(5)
2.185(6)
2.181(6)
N(1)–Ru(1)–O(1)
N(1)–Ru(1)–Cl(1)
O(1)–Ru(1)–Cl(1)
79.1(2)
83.31(13)
86.23(11)
The results obtained (Table 7) clearly demonstrate that it is in
principle possible to regenerate the formate anion consumed in
the catalytic regeneration of NADH in aqueous solution [13] by
using the oxinato complex [(g g
6-MeC6H4Pri)Ru( 2-NC9H6O)(OH2)]+
(12). However, 12[BF4] cannot simply be coupled to the [(g5
-
C5Me5)Rh(phen)(OH2)]2+ (phen = ortho-phenanthroline) catalyst,
since the latter one is active at pH 7, whereas 12[BF4] requires
pH 14 despite a much lower catalytic activity.
3. Experimental
3.1. General
All manipulations were carried out in an inert atmosphere using
standard Schlenk techniques and pure solvents. The starting materi-
als [(
methods [40]. Complex [(
g
6-arene)RuCl2]2 were prepared according to the published
g
6-MeC6H4Pri)Ru( 2-NC9H6O)Cl] (1) was
g
synthesized according to the literature report [38]. All other re-
agents were commercially available and were used without further
purification. NMR spectra were recorded on a Bruker 400 MHz spec-
trometer. Electro-spray mass spectra were obtained in positive- or
negative-ion mode with an LCQ Finnigan mass spectrometer. Micro-
analyses were carried out by the Mikroelementaranalytisches
Laboratorium, ETH Zürich (Switzerland).
Fig. 4. Molecular structure of cation 12.

T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
3977
Table 4
Table 6
Selected bond lengths (Å) and angles (°) in 12[BF4].
Hydrogenation of carbon dioxide to give formic acid (as formate) using 1, 4, 9, 10 and
12[BF4] as catalyst precursors in aqueous solution.a
Interatomic distances
Bond angles
Catalyst
TONb,c
Yield (mmol)
Ru(1)–O(1)
Ru(1)–N(1)
Ru(1)–O(2)
Ru(1)–C(10)
Ru(1)–C(11)
Ru(1)–C(12)
Ru(1)–C(13)
Ru(1)–C(14)
Ru(1)–C(15)
2.066(3)
2.085(3)
2.132(3)
2.152(4)
2.145(4)
2.172(4)
2.191(4)
2.174(4)
2.168(4)
N(1)–Ru(1)–O(1)
N(1)–Ru(1)–O(2)
O(1)–Ru(1)–O(2)
79.07(12)
82.14(14)
82.68(13)
1
4
9
10
77
60
94
122
128
0.185
0.123
0.204
0.260
0.264
12[BF4]
a
Conditions: 50 mL reaction vessel, 20 mL KOH 1 M, 2
20 bar CO2, 20 h at 80 °C.
l
mol catalyst, 20 bar H2,
b
Turnover number = mol of product (formate)/mol of catalyst. TON is a unitless
parameter.
c
Determined by 1H NMR measurement of the resulting solution with TSP (3-
(trimethylsilyl)propionic-2,2,3,3-d4 acid sodium salt) in D2O as the reference and
the internal standard.
Table 7
pH dependence for the hydrogenation of carbon dioxide of 12[BF4] in aqueous
solution.a
pH
TONb,c
Yield (mmol)
3
9
0
3
128
0
0.007
0.264
14 (KOH 1 M)
a
Conditions: 50 mL reaction vessel, 20 mL aqueous solution with pH desired,
mol catalyst, 20 bar H2, 20 bar CO2, 20 h at 80 °C.
Turnover number = mol of product (formate)/mol of catalyst. TON is a unitless
2
l
b
parameter.
c
Determined by 1H NMR measurement of the resulting solution with TSP (3-
(trimethylsilyl)propionic-2,2,3,3-d4 acid sodium salt) in D2O as the reference and
the internal standard.
Fig. 5. Molecular structure of cation 15.
Table 5
Selected bond lengths (Å) and angles (°) in 15[BF4].
Interatomic distances
Bond angles
Ru(1)–O(1)
Ru(1)–N(1)
Ru(1)–O(2)
Ru(1)–C(12)
Ru(1)–C(13)
Ru(1)–C(14)
Ru(1)–C(15)
Ru(1)–C(16)
Ru(1)–C(17)
2.048(6)
2.063(7)
2.140(6)
2.210(9)
2.188(8)
2.151(10)
2.146(10)
2.134(10)
2.167(9)
N(1)–Ru(1)–O(1)
N(1)–Ru(1)–O(2)
O(1)–Ru(1)–O(2)
78.7(3)
84.6(2)
83.9(2)
Fig. 6. Temperature-dependence of TON for the hydrogenation of carbon dioxide
catalyzed by 12[BF4] in aqueous solution. (Conditions: 2 lmol catalyst, 25 bar of H2,
25 bar of CO2, 50 mL reaction vessel, 20 mL aqueous Et3N solution (0.25 M) at the
desired temperature, the reaction was stirred for 20 h.)
tation was completed by addition of diethyl ether (5 mL). The
solid was isolated by decanting and dissolved in dichloromethane
(5 mL). The solution was filtered and then concentrated to 1 mL.
Upon addition of diethyl ether an orange precipitate formed, which
was isolated by decanting and washed with Et2O (3 ꢂ 2 mL). The
product was purified by column on silica gel (CH2Cl2:acetone from
97:3 to 80:20) and dried in vacuo.
3.2. General procedure for the synthesis of complex
[(
6-MeC6H4Pri)Ru( 2-N,O-L)Cl] (2–5)
g
g
The potassium oxinates KL (L = NC9H4Cl2O, NC9H5ClO,
NC9H5(NO2)O, NC9H3MeCl2O) have been synthesized by adding
KOH to a solution of the oxine in ethanol; after filtration the solu-
tion was reduced to dryness [38]. To a solution of [(g
6-MeC6H4-
Pri)RuCl2]2 (50 mg, 0.082 mmol) in THF (8 mL), 2 equiv. of solid
KL (L = NC9H4Cl2O, NC9H5ClO, NC9H5(NO2)O, NC9H3MeCl2O)
(0.163 mmol) was added and the reaction mixture stirred for 2 h
at room temperature. When the volume was reduced to 2 mL un-
der high vacuum, an orange precipitate formed. Then the precipi-
3.2.1. [(g g
6-MeC6H4Pri)Ru( 2-NC9H4Cl2O)Cl]: (2) yield: 72% (56.7 mg)
Anal. Calc. for C19H18NOCl3Ru: C, 47.17; H, 3.75; N, 2.90. Found:
C, 47.51; H, 3.88; N, 2.91%. 1H NMR (400 MHz, CD2Cl2): d 1.14 (d,
J = 8 Hz, 3H, CH-(CH3)2), 1.22 (d, J = 8 Hz, 3H, CH-(CH3)2), 2.33 (s,
3H, CH3), 2.84 (m, 1H, CH-(CH3)2), 5.36 (d, J = 8 Hz, 1H, C6H4),

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T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
(100 MHz, CDCl3): d 18.85 (CH3), 22.23 (CH-(CH3)2), 22.57 (CH-
(CH3)2), 31.12 (CH-(CH3)2), 80.80 (1CH, C6H4), 81.32 (1CH, C6H4),
82.00 (1CH, C6H4), 82.80 (1CH, C6H4), 99.10 (1C, C6H4), 101.57
(1C, C6H4), 112.39 (1C, C9H5), 114.62 (1CH, C9H5), 122.68 (1CH,
C9H5), 127.47 (1C, C9H5), 130.04 (1CH, C9H5), 134.99 (1CH, C9H5),
144.83 (1C, C9H5), 148.86 (1CH, C9H5), 168.04 (1C, C9H5). MS
(ESI) m/z = 414 [MꢁCl]+.
3.2.3. [(
(50.3 mg)
g g
6-MeC6H4Pri)Ru( 2-NC9H5(NO2)O)Cl]: (4) yield: 67%
Anal. Calc. for C19H19N2O3ClRu: C, 49.62; H, 4.16; N, 6.09.
Found: C, 50.09; H, 4.37; N, 5.85%. 1H NMR (400 MHz, CDCl3): d
1.21 (d, J = 8 Hz, 6 H, CH-(CH3)2), 2.33 (s, 3H, CH3), 2.82 (m, 1H,
CH-(CH3)2), 5.38 (d, J = 4 Hz, 1H, C6H4), 5.49 (d, J = 4 Hz, 1H,
C6H4), 5.56 (d, J = 4 Hz, 1H, C6H4), 5.66 (d, J = 4 Hz, 1H, C6H4),
6.89 (d, J = 8 Hz, 1H, C9H5), 7.62 (m, 1H, C9H5), 8.54 (d, J = 8 Hz,
1H, C9H5), 9.00 (d, J = 4 Hz, 1H, C9H5), 9.50 (d, J = 8 Hz, 1H, C9H5).
13C {1H} NMR (100 MHz, CDCl3): d 18.87 (CH3), 22.31 (CH-
(CH3)2), 22.47 (CH-(CH3)2), 31.22 (CH-(CH3)2), 80.90 (1CH, C6H4),
81.96 (1CH, C6H4), 82.55 (1CH, C6H4), 82.85 (1CH, C6H4), 99.39
(1C, C6H4), 102.53 (1C, C6H4), 113.58 (1CH, C9H5), 125.70 (1CH,
C9H5), 126.07 (1C, C9H5), 129.24 (1C, C9H5), 132.34 (1CH, C9H5),
135.95 (1CH, C9H5), 143.38 (1C, C9H5), 149.61 (1CH, C9H5),
176.85 (1C, C9H5). MS (ESI) m/z = 425 [MꢁCl]+.
Fig. 7. Time-dependence of TON for the hydrogenation of carbon dioxide catalyzed
by 12[BF4] in aqueous solution. (Conditions: 2 lmol catalyst, 50 bar of H2, 50 bar of
CO2, 50 mL reaction vessel, 20 mL aqueous Et3N solution (0.25 M) at 100 °C, the
reaction was stirred for desired time.)
5.46 (m, 2H, C6H4), 5.68 (d, J = 8 Hz, 1H, C6H4), 7.43 (m, 1H, C9H4),
7.51 (s, 1H, C9H4), 8.36 (d, J = 8 Hz, C9H4), 8.96 (d, J = 4 Hz, C9H4).
13C {1H} NMR (100 MHz, CDCl3): d 18.77 (CH3), 22.27 (1C, CH-
(CH3)2), 22.45 (1C, CH-(CH3)2), 31.15 (1C, CH-(CH3)2), 80.57 (1CH,
C6H4), 81.92 (1CH, C6H4), 82.08 (1CH, C6H4), 82.75 (1CH, C6H4),
98.90 (1C, C6H4), 101.76 (1C, C9H4), 112.14 (CH, C9H4), 118.75
(1C, C9H4), 122.53 (1CH, C9H4), 126.38 (1C, C9H4), 130.21 (1CH,
C9H4), 135.14 (1CH, C9H4), 144.76 (1C, C9H4), 149.77 (1CH, C9H4),
163.16 (1C, C9H4). MS (ESI) m/z = 448 [MꢁCl]+.
3.2.4. [(
(61.4 mg)
g g
6-MeC6H4Pri)Ru( 2-NC9H3MeCl2O)Cl]: (5) yield: 76%
Anal. Calc. for C20H20NOCl3Ru: C, 48.25; H, 4.05; N, 2.81. Found:
C, 48.45; H, 4.02; N, 2.81%. 1H NMR (400 MHz, CD2Cl2): d 0.95 (d,
J = 8 Hz, 3H, CH-(CH3)2), 1.11 (d, J = 4 Hz, 3H, CH-(CH3)2), 2.29 (s,
3H, CH3), 2.62 (m, 1H, CH-(CH3)2), 3.16 (s, 3H, CH3), 5.27 (d,
J = 4 Hz, 1H, C6H4), 5.54 (m, 2H, C6H4), 5.70 (d, J = 4 Hz, 1H, C6H4),
7.40 (s, 1H, C9H3), 7.42 (d, J = 8 Hz, 1H, C9H3), 8.23 (d, J = 8 Hz,
1H, C9H3). 13C {1H} NMR (100 MHz, CD2Cl2): d 18.67 (CH3), 21.75
(1C, CH-(CH3)2), 22.05 (1C, CH-(CH3)2), 28.66 (Me), 30.99 (CH-
(CH3)2), 79.56 (1CH, C6H4), 79.72 (1CH, C6H4), 80.74 (1CH, C6H4),
86.34 (1CH, C6H4), 100.47 (1C, C6H4), 101.90 (1C, C6H4), 111.80
(1C, C9H3), 118.33 (1C, C9H3), 124.18 (1CH, C9H3), 124.59 (1C,
3.2.2. [(g g
6-MeC6H4Pri)Ru( 2-NC9H5ClO)Cl]: (3) yield: 74% (54.2 mg)
Anal. Calc. for C19H19NOCl2Ru: C, 50.79; H, 4.26; N, 3.12. Found:
C, 50.93; H, 4.45; N, 3.09%. 1H NMR (400 MHz, CDCl3): d 1.16 (d,
J = 4 Hz, 6 H, CH-(CH3)2), 2.31 (s, 3 H, CH3), 2.78 (m, 1H, CH-
(CH3)2), 5.31 (d, J = 4 Hz, 1H, C6H4), 5.43 (d, J = 4 Hz, 1H, C6H4),
5.49 (d, J = 4 Hz, 1H, C6H4), 5.60 (d, J = 4 Hz, 1H, C6H4), 6.92 (d,
J = 8 Hz, 1H, C9H5), 7.36 (d, J = 8 Hz, 1H, C9H5), 7.44 (m, 1H, C9H5),
8.38 (d, J = 8 Hz, 1H, C9H5), 8.94 (d, J = 4 Hz, C9H5). 13C {1H} NMR
Table 8
Crystallographic and structure refinement parameters for complexes 5, 6, 11, 12[BF4] and 15[BF4]ꢀ0.25H2O.
5
6
11
12[BF4]
15[BF4]ꢀ0.25H2O
Chemical formula
Formula weight
Crystal system
Space group
Crystal color and shape
Crystal size
a (Å)
C20H20Cl3NORu
497.79
C21H24ClNORu
442.93
C22H24Cl3NORu
525.84
C19H22BF4NO2Ru
484.26
C21H26.5BF4NO2.25Ru
516.81
Monoclinic
P21/n (no. 14)
Orange block
0.27 ꢂ 0.22 ꢂ 0.19
14.513(1)
8.1149(6)
16.678(1)
90
102.190(9)
90
1919.9(3)
4
Monoclinic
P21/c (no. 14)
Orange block
0.25 ꢂ 0.22 ꢂ 0.16
13.936(2)
7.7228(7)
17.189(2)
90
96.086(15)
90
1839.6(3)
4
Monoclinic
P21/a (no. 14)
Orange block
0.16 ꢂ 0.14 ꢂ 0.11
14.399(2)
9.0695(10)
16.991(3)
90
114.650(15)
90
2016.7(5)
4
Orthorhombic
Pcab (no. 61)
Red plate
0.20 ꢂ 0.18 ꢂ 0.17
14.3671(9)
16.1713(8)
16.8419(9)
90
90
90
3913.0(4)
8
Triclinic
ꢀ
P1 (no. 2)
Orange block
0.25 ꢂ 0.22 ꢂ 0.17
9.8825(7)
19.9322(15)
23.578(2)
74.572(9)
80.207(9)
85.036(9)
4407.6(6)
8
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
T (K)
203(2)
1.722
1.244
203(2)
1.599
1.006
203(2)
1.732
1.189
203(2)
1.644
0.852
203(2)
1.558
0.763
Dc (g cmꢁ3
)
l
(mmꢁ1
)
Scan range (°)
Unique reflections
Reflections used [I > 2
Rint
2.05 < h < 26.05
3754
3118
2.38 < h < 26.08
3607
1775
2.60 < h < 26.07
3919
2643
2.25 < h < 29.31
5315
3049
2.08 < h < 26.08
15 849
5579
r
(I)]
0.0294
0.1102
0.0679
0.1471
0.1389
Final R indices [I > 2
R indices (all data)
Goodness-of-fit
r
(I)]a
0.0217, wR2 0.0507
0.1090, wR2 0.0691
0.948
0.0405, wR2 0.0610
0.0599, wR2 0.0741
0.703
0.732, ꢁ0.672
0.0352, wR2 0.0698
0.1093, wR2 0.1044
0.906
0.943, ꢁ1.226
0.0495, wR2 0.0907
0.1591, wR2 0.1096
0.911
0.787, ꢁ0.742
0.0529, wR2 0.0958
0.0292, wR2 0.0521
0.734
0.542, ꢁ0.642
Max, Min
D
q
/e (Åꢁ3
)
0.721, ꢁ0.717
P
P
P
2
2
1=2
2
Structures were refined on Fo2 : wR2 ¼ ½ ½wðFo2 ꢁ Fc2Þ ꢃ= wðFo2Þ ꢃ , where wꢁ1 ¼ ½ ðF2oÞ þ ðaPÞ þ bPꢃ and P ¼ ½maxðFo2; 0Þ þ 2F2c ꢃ=3.
a

T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
3979
+
Ru
N
O
OH2
Ru
N
CO2
O
H
O
OH-
O
12
Cl-
Ru
N
H
O
H2O
HCOO-
H2O
Ru
OH
O
Ru
N
O
Cl
N
H2
1
Scheme 2. Postulated catalytic cycle for the hydrogenation of carbon dioxide in water using a 8-hydroxyquinoline complex under basic conditions.
C9H3), 128.55 (1CH, C9H3), 134.74 (1CH, C9H3), 144.54 (1C, C9H3),
C9H4), 126.36 (1C, C9H4), 129.53 (1CH, C9H4), 134.34 (1CH, C9H4),
145.68 (1C, C9H4), 148.13 (1CH, C9H4), 162.46 (1C, C9H4). MS
(ESI) m/z = 476 [MꢁCl]+.
160.19 (1C, C9H3), 162.79 (1C, C9H3). MS (ESI) m/z = 462 [MꢁCl]+.
3.3. General procedure for the synthesis of complex [(
Ru(
2-N,O-L)Cl] (6–11)
g
6-C6Me6)
3.3.3. [(g g
6-C6Me6)Ru( 2-NC9H5ClO)Cl]: (8) yield: 50% (38.5 mg)
g
Anal. Calc. for C23H28NOClRu: C, 52.83; H, 4.86, N, 2.93. Found:
C, 52.91; H, 4.97; N, 2.88%. 1H NMR (400 MHz, CDCl3): d 2.13 (s,
18H, C6(CH3)6), 6.90 (d, J = 8 Hz, 1H, C9H5), 7.32 (d, J = 8 Hz, 1H,
C9H5), 7.43 (t, J = 4 Hz, J = 8 Hz, 1H, C9H5), 8.31 (d, J = 8 Hz, 1H,
C9H5), 8.63 (d, J = 4 Hz, 1H, C9H5). 13C {1H} NMR (100 MHz, CDCl3):
d 15.64 (6C, C6(CH3)6), 91.67 (6C, C6(CH3)6), 111.60 (1C, C9H5),
114.55 (1CH, C9H5), 122.47 (1CH, C9H5), 127.55 (1C, C9H5),
129.87 (1CH, C9H5), 134.43 (1CH, C9H5), 146.03 (1C, C9H5),
146.96 (1CH, C9H5), 167.61 (1C, C9H5). MS (ESI) m/z = 442 [MꢁCl]+.
The sodium oxinates NaL (L = NC9H6O, NC9H4Cl2O, NC9H5ClO,
NC9H5(NO2)O, NC9H4Me2O, NC9H3MeCl2O) have been synthesized
by adding MeONa to a solution of the oxine LH in methanol; after
filtration the solution was reduced to dryness [38]. To a solution of
[(g
6-C6Me6)RuCl2]2 (55 mg, 0.082 mmol) in chloroform (10 mL),
2 equiv. of solid NaL (0.163 mmol) was added and the reaction
mixture was heated under reflux for 2 h. The solution was cooled
to room temperature and then the solvent was reduced to 1 mL,
precipitation was completed by addition of Et2O, the solid was
washed by Et2O (2 ꢂ 2 mL) and dried under vacuum. The product
was purified by the column on silica gel (CH2Cl2:acetone from
95:5 to 80:20) and dried in vacuo.
3.3.4. [(g g
6-C6Me6)Ru( 2-NC9H5(NO2)O)Cl]: (9) yield: 65% (51.7 mg)
Anal. Calc. for C21H23N2O3ClRu: C, 51.69; H, 4.75; N, 5.74.
Found: C, 51.52; H, 4.87; N, 5.45%. 1H NMR (400 MHz, CD2Cl2): d
2.12 (s, 18H, C6(CH3)6), 6.79 (d, J = 8 Hz, 1H, C9H5), 7.65 (m, 1H,
C9H5), 8.47 (d, J = 8 Hz, 1H, C9H5), 8.69 (d, J = 4 Hz, 1H, C9H5), 9.41
(d, J = 8 Hz, 1H, C9H5). 13C {1H} NMR (100 MHz, CD2Cl2): d 15.39
(6C, C6(CH3)6), 92.15 (6C, C6(CH3)6), 112.85 (1CH, C9H5), 125.63
(1CH, C9H5), 126.18 (1C, C9H5), 128.52 (1C, C9H5), 131.94 (1CH,
C9H5), 134.95 (1CH, C9H5), 144.40 (1C, C9H5), 147.78 (1CH, C9H5),
176.51 (1C, C9H5). MS (ESI) m/z = 453 [MꢁCl]+.
3.3.1. [(g g
6-C6Me6)Ru( 2-NC9H6O)Cl]: (6) yield: 74% (53.4 mg)
Anal. Calc. for C21H24NOClRu: C, 56.94; H, 5.46; N, 3.16. Found:
C, 56.70; H, 5.62; N, 3.01%. 1H NMR (400 MHz, CDCl3): d 2.13 (s,
18H, C6(CH3)6), 6.74 (d, J = 8 Hz, 1H, C9H6), 6.99 (d, J = 8 Hz, 1H,
C9H6), 7.28 (d, J = 4 Hz, 1H, C9H6), 7.30 (d, J = 4 Hz, 1H, C9H6), 7.98
(d, J = 8 Hz, 1H, C9H6), 8.59 (d, J = 4 Hz, 1H, C9H6). 13C {1H} NMR
(100 MHz, CDCl3): d 15.63 (6C, C6(CH3)6), 91.53 (6C, C6(CH3)6),
109.84 (1CH, C9H6), 115.13 (1CH, C9H6), 121.73 (1CH, C9H6),
130.27 (1CH, C9H6), 130.47 (1C, C9H6), 137.18 (1CH, C9H6),
145.76 (1C, C9H6), 146.61 (1CH, C9H6), 168.27 (1C, C9H6). MS
(ESI) m/z = 407 [MꢁCl]+.
3.3.5. [(g g
6-C6Me6)Ru( 2-NC9H4Me2O)Cl]: (10) yield: 80% (62 mg)
Anal. Calc. for C23H28NOClRu: C, 58.65; H, 5.99, N, 2.97. Found:
C, 58.41; H, 6.06; N, 2.84%. 1H NMR (400 MHz, CDCl3): d 2.10 (s,
18H, C6(CH3)6), 2.44 (s, 6 H, 2Me), 7.07 (s, 1H, C9H4), 7.27 (t,
J = 4 Hz, J = 8 Hz, 1H, C9H4), 8.05 (d, J = 8 Hz, 1H, C9H4), 8.59 (d,
J = 4 Hz, 1H, C9H4). 13C {1H} NMR (100 MHz, CDCl3): d 15.23
(C6(CH3)6), 16.04 (1C, Me), 16.83 (1C, Me), 91.15 (6C, C6(CH3)6),
115.34 (1C, C9H4), 120.01 (1CH, C9H4), 123.30 (1C, C9H4), 126.93
(1C, C9H4), 132.50 (1CH, C9H4), 133.78 (1CH, C9H4), 144.58 (1C,
C9H4), 146.14 (1CH, C9H4), 163.58 (1C, C9H4). MS (ESI) m/z = 436
[MꢁCl]+.
3.3.2. [(g g
6-C6Me6)Ru( 2-NC9H4Cl2O)Cl]: (7) yield: 72% (59.7 mg)
Anal. Calc. for C21H22NOCl3Ru: C, 49.28; H, 4.33; N, 2.74. Found:
C, 48.85; H, 4.53; N, 2.61%. 1H NMR (400 MHz, CD2Cl2): d 2.11 (s,
18H, C6(CH3)6), 7.47 (s, 1H, C9H4), 7.48 (t, J = 4 Hz, J = 8 Hz, 1H,
C9H4), 8.31 (d, J = 8 Hz, 1H, C9H4), 8.66 (d, J = 4 Hz, 1H, C9H4). 13C
{1H} NMR (100 MHz, CD2Cl2): d 15.25 (6C, C6(CH3)6), 91.73 (6C,
C6(CH3)6), 111.01 (1C, C9H4), 117.57 (1C, C9H4), 122.55 (1CH,

3980
T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
3.3.6. [(
g
6-C6Me6)Ru(
g
2-NC9H3MeCl2O)Cl]: (11) yield: 85% (72.5 mg)
CH-(CH3)2), 30.49 (1C, CH-(CH3)2), 79.88 (2CH, C6H4), 82.76 (2CH,
C6H4), 98.30 (1C, C6H4), 100.06 (1C, C6H4), 114.04 (1CH, C9H5),
115.41 (1C, C9H5), 123.81 (1CH, C9H5), 127.21 (1C, C9H5), 129.42
(1CH, C9H5), 136.34 (1CH, C9H5), 143.04 (1C, C9H5), 152.32 (1CH,
C9H5), 164.56 (1C, C9H5). MS (ESI) m/z = 414 [MꢁBF4ꢁH2O]+.
Anal. Calc. for C22H24NOCl3Ru: C, 50.25; H, 4.60; N, 2.66. Found:
C, 50.45; H, 4.67; N, 2.65%. 1H NMR (400 MHz, CDCl3): d 2.03 (s,
18H, C6(CH3)6), 3.08 (s, 3H, CH3), 7.32 (d, J = 8 Hz, 1H, C9H3), 7.39
(s, 1H, C9H3), 8.16 (d, J = 8 Hz, C9H3). 13C {1H} NMR (100 MHz,
CDCl3):
d 16.02 (6C, C6(CH3)6), 27.99 (1C, Me), 91.76 (6C,
C6(CH3)6), 111.37 (1C, C9H3), 119.26 (1C, C9H3), 123.58 (1CH,
C9H3), 124.57 (1C, C9H3), 128.50 (1CH, C9H3), 134.36 (1CH, C9H3),
145.69 (1C, C9H3), 160.33 (1C, C9H3), 162.55 (1C, C9H3). MS (ESI)
m/z = 490 [MꢁCl]+.
3.4.4. [(
99% (83.1 mg)
g g
6-MeC6H4Pri)Ru( 2-NC9H4Me2O)(OH2)][BF4]: 15[BF4] yield:
Anal. Calc. for 15[BF4]ꢀH2O, C21H28BF4NO3Ru: C, 47.56; H, 5.32;
N, 2.64. Found: C, 47.82; H, 5.30; N, 2.72%. 1H NMR (400 MHz,
D2O): d 0.98 (d, J = 4 Hz, 6 H, CH-(CH3)2), 2.21 (s, 3H, CH3), 2.37
(s, 3H, CH3), 2.49 (s, 3H, CH3), 5.75 (d, J = 8 Hz, 2H, C6H4), 5.95 (d,
J = 8 Hz, 2H, C6H4), 7.24 (s, 1H, C9H4), 7.61 (m, 1H, C9H4), 8.49 (d,
J = 8 Hz, 1H, C9H4), 9.50 (d, J = 4 Hz, 1H, C9H4). 13C {1H} NMR
(100 MHz, D2O): d 15.71 (CH3), 16.08 (CH3), 17.79 (CH3), 21.24
(2C, CH-(CH3)2), 30.56 (CH-(CH3)2), 80.33 (2CH, C6H4), 82.74
(2CH, C6H4), 97.54 (1C, C6H4), 100.09 (1C, C6H4), 120.97 (1C,
C9H4), 121.58 (1CH, C9H4), 124.37 (1C, C9H4), 127.29 (1C, C9H4),
132.48 (1CH, C9H4), 136.53 (1CH, C9H4), 142.51 (1C, C9H4),
151.51 (1CH, C9H4), 160.80 (1C, C9H4). MS (ESI) m/z = 408
[MꢁBF4ꢁH2O]+.
3.4. Preparation of the aqua complexes [(
Ru(
2-N,O-L)(OH2)][BF4] (12[BF4]–19[BF4])
g
6-arene)
g
A mixture of [(g
6-arene)RuCl2]2 (0.082 mmol) and 2 equiv. of
silver sulfate (0.163 mmol) in water (10 mL) was stirred for 2 h
in the dark at room temperature. After this time, the yellow solu-
tion was filtered and then added the neat oxine LH (L = NC9H6O,
NC9H4Cl2O, NC9H5ClO, NC9H5(NO2)O, NC9H4Me2O, NC9H3MeCl2O)
(0.163 mmol). Then the solution was again stirred for 2 h in the
dark at room temperature, during this time the color changed from
yellow to orange or red. The product was precipitated by adding a
saturated aqueous solution of NaBF4. The tetrafluoroborate salt
was obtained by crystallization from water as orange-red crystals.
3.4.5. [(
(61 mg)
g g
6-C6Me6)Ru( 2-NC9H6O)(OH2)][BF4]: 16[BF4] yield: 73%
Anal. Calc. for C21H26BF4NO2Ru: C, 49.23; H, 5.12; N, 2.73.
Found: C, 49.19; H, 5.00; N, 2.86%. 1H NMR (400 MHz, D2O): d
2.12 (s, 18H, C6(CH3)6), 7.01 (d, J = 8 Hz, 1H, C9H6), 7.07 (d,
J = 8 Hz, 1H, C9H6), 7.40 (t, 1H, C9H6), 7.63 (m, 1H, C9H6), 8.32 (d,
J = 8 Hz, 1H, C9H6), 9.09 (d, J = 4 Hz, 1H, C9H6). 13C {1H} NMR
(100 MHz, D2O): d 14.93 (6CH, C6(CH3)6), 91.68 (6C, C6(CH3)6),
113.33 (1CH, C9H6), 114.20 (1CH, C9H6), 123.01 (1CH, C9H6),
129.96 (1C, C9H6), 130.18 (1CH, C9H6), 138.96 (1CH, C9H6),
143.78 (1C, C9H6), 150.05 (1CH, C9H6), 165.01 (1C, C9H6). MS
(ESI) m/z = 408 [MꢁBF4ꢁH2O]+.
3.4.1. [(
(71 mg)
g g
6-MeC6H4Pri)Ru( 2-NC9H6O)(OH2)][BF4]: 12[BF4] yield: 89%
Anal. Calc. for C19H22BF4NO2Ru: C, 47.12; H, 4.58; N, 2.89.
Found: C, 47.32; H, 4.74; N, 2.95%. 1H NMR (400 MHz, D2O): d
0.98 (d, J = 8 Hz, 6 H, CH-(CH3)2), 2.17 (s, 3H, CH3), 2.59 (m, 1H,
CH-(CH3)2), 5.74 (d, J = 8 Hz, 2H, C6H4), 5.95 (d, J = 8 Hz, 2H,
C6H4), 7.03 (d, J = 8 Hz, 1H, C9H6), 7.16 (d, J = 8 Hz, 1H, C9H6), 7.44
(t, 1H, C9H6), 7.63 (t, 1H, C9H6), 8.40 (d, J = 8 Hz, 1H, C9H6), 8.49
(d, J = 4 Hz, 1H, C9H6). 13C {1H} NMR (100 MHz, D2O): d 17.77
(CH3), 21.30 (2C, CH-(CH3)2), 30.61 (1C, CH-(CH3)2), 79.98 (2CH,
C6H4), 82.75 (2CH, C6H4), 98.16 (1C, C6H4), 100.05 (1C, C6H4),
114.11 (1CH, C9H6), 114.60 (1CH, C9H6), 123.23 (1CH, C9H6),
130.04 (1CH, C9H6), 130.21 (1C, C9H6), 139.56 (1CH, C9H6),
142.55 (1C, C9H6), 151.95 (1CH, C9H6), 164.98 (1C, C9H6). MS
(ESI) m/z = 380 [MꢁBF4ꢁH2O]+.
3.4.6. [(
(88 mg)
g g
6-C6Me6)Ru( 2-NC9H3Cl2MeO)(OH2)][BF4]: 17[BF4] yield: 90%
Anal. Calc. for C22H26BCl2F4NO2Ru: C, 44.39; H, 4.40; N, 2.35.
Found: C, 44.40; H, 4.41; N, 2.41%. 1H NMR (400 MHz, D2O): d
1.99 (s, 18H, C6(CH3)6), 3.16 (s, 3H, CH3), 7.35 (s, 1H, C9H3), 7.66
(d, J = 8 Hz, 1H, C9H3), 8.37 (d, J = 8 Hz, 1H, C9H3). 13C {1H} NMR
(100 MHz, D2O): d 15.19–15.29 (6C, C6(CH3)6), 27.73 (1C, CH3),
91.78 (6C, C6(CH3)6), 114.80 (1C, C9H3), 118.41 (1C, C9H3), 124.35
(1C, C9H3), 124.73 (1CH, C9H3), 127.61 (1CH, C9H3), 135.40 (1CH,
C9H3), 144.72 (1C, C9H3), 145.74 (1C, C9H3), 163.28 (1C, C9H3).
MS (ESI) m/z = 490 [MꢁBF4ꢁH2O]+.
3.4.2. [(
83% (74.6 mg)
g g
6-MeC6H4Pri)Ru( 2-NC9H3MeCl2O)(OH2)][BF4]: 13[BF4] yield:
Anal. Calc. for C20H22BCl2F4NO2Ru: C, 42.35; H, 3.91; N, 2.4.
Found: C, 42.57; H, 3.72; N, 2.57%. 1H NMR (400 MHz, D2O): d
0.90 (d, J = 4 Hz, 6 H, CH-(CH3)2), 2.24 (s, 3H, CH3), 2.41 (m, 1H,
CH-(CH3)2), 3.34 (s, 3H, CH3), 5.86 (d, J = 4 Hz, 2H, C6H4), 6.08 (d,
J = 8 Hz, 2H, C6H4), 7.61 (s, 1H, C9H3), 7.71 (d, J = 8 Hz, 1H, C9H3),
8.49 (d, J = 8 Hz, 1H, C9H3). 13C {1H} NMR (100 MHz, D2O): d
17.77 (1CH, CH3), 21.08 (2CH, CH-(CH3)2), 28.57 (1CH, CH3),
30.37 (1CH, CH-(CH3)2), 79.33 (2CH, C6H4), 81.67 (1CH, C6H4),
85.99 (1CH, C6H4), 96.80 (1C, C6H4), 101.53 (1C, C6H4), 115.39
(1C, C9H3), 118.61 (1C, C9H3), 124.59 (1C, C9H3), 125.12 (1CH,
C9H3), 128.33 (1CH, C9H3), 136.22 (1CH, C9H3), 143.93 (1C, C9H3),
160.31 (1C, C9H3), 163.72 (1C, C9H3). MS (ESI) m/z = 462
[MꢁBF4ꢁH2O]+.
3.4.7. [(
(56 mg)
g g
6-C6Me6)Ru( 2-NC9H5(NO2)O)(OH2)][BF4]: 18[BF4] yield: 61%
Anal. Calc. for C21H25BF4N2O4Ru: C, 45.26; H, 4.52; N, 5.03.
Found: C, 45.03; H, 4.80; N, 5.24%. 1H NMR (400 MHz, D2O): d
2.12 (s, 18H, C6(CH3)6), 6.93 (d, J = 8 Hz, 1H, C9H5), 7.88 (m, 1H,
C9H5), 8.52 (d, J = 8 Hz, 1H, C9H5), 9.17 (d, J = 4 Hz, 1H, C9H5), 9.39
(d, J = 8 Hz, 1H, C9H5). 13C {1H} NMR (100 MHz, D2O): d 14.93
(6CH, C6(CH3)6), 92.38 (6C, C6(CH3)6), 113.00 (1CH, C9H5), 125.61
(1C, C9H5), 126.71 (1CH, C9H5), 130.33 (1C, C9H5), 132.46 (1CH,
C9H5), 136.11 (1CH, C9H5), 150.90 (1CH, C9H5), 174.88 (1C, C9H5).
MS (ESI) m/z = 453 [MꢁBF4ꢁH2O]+.
3.4.3. [(
75% (63.5 mg)
g g
6-MeC6H4Pri)Ru( 2-NC9H5ClO)(OH2)][BF4]: 14[BF4] yield:
Anal. Calc. for C19H21BClF4NO2Ru: C, 43.99; H, 4.08; N, 2.70.
Found: C, 43.74; H, 4.25; N, 2.79%. 1H NMR (400 MHz, D2O): d
1.01 (d, J = 4 Hz, 6 H, CH-(CH3)2), 2.19 (s, 3H, CH3), 2.61 (m, 1H,
CH-(CH3)2), 5.77 (d, J = 4 Hz, 2H, C6H4), 5.98 (d, J = 8 Hz, 2H,
C6H4), 6.97 (d, J = 8 Hz, 1H, C9H5), 7.51 (d, J = 8 Hz, 1H, C9H5), 7.77
(m, 1H, C9H5), 8.65 (d, J = 8 Hz, 1H, C9H5), 9.57 (d, J = 4 Hz, 1H,
C9H5). 13C {1H} NMR (100 MHz, D2O): d 17.64 (CH3), 21.17 (2C,
3.4.8. [(
(87 mg)
g g
6-C6Me6)Ru( 2-NC9H4Me2O)(OH2)][BF4]: [19][BF4] yield: 98%
Anal. Calc. for C23H30BF4NO2Ru: C, 51.12; H, 5.60; N, 2.59.
Found: C, 50.93; H, 5.70; N, 2.70%. 1H NMR (100 MHz, D2O): d
2.12 (s, 18H, C6(CH3)6), 2.36 (s, 3H, CH3), 2.52 (s, 3H, CH3), 7.23
(s, 1H, C9H4), 7.65 (m, 1H, C9H4), 8.45 (d, J = 8 Hz, 1H, C9H4), 9.09
(d, J = 4 Hz, 1H, C9H4). 13C {1H} NMR (100 MHz, D2O): d 14.52

T.-T. Thai et al. / Journal of Organometallic Chemistry 694 (2009) 3973–3981
3981
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3.5. X-ray crystallography
Crystals of complexes 5, 6, 11, 12[BF4] and 15[BF4] were
mounted on a Stoe Image Plate Diffraction system equipped with
a u circle goniometer, using Mo Ka graphite monochromated radi-
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solved by direct methods using the program SHELXS-97 [41]. Refine-
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[42]. The H-atoms were included in calculated positions and trea-
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atoms were refined anisotropically, using weighted full-matrix
least-square on F2. Crystallographic details are summarized in Ta-
ble 8. Figures of complexes 5, 6, 11, 12[BF4] and 15[BF4] were
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The hydrogenation of carbon dioxide using 1, 4, 9, 10 or 12[BF4]
as catalyst (2 lmol) was carried out in aqueous solution (20 mL)
under basic conditions. The solution was pressurized in an auto-
clave with H2 and CO2 and stirred for the time indicated at the gi-
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4. Supplementary material
CCDC 703775, 703776, 703777, 703778, and 703779 contain
the supplementary crystallographic data for complex 5, 6, 11,
12[BF4] and 15[BF4]ꢀ0.25H2O. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
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Acknowledgements
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Financial support of this work by the Swiss National Science
Foundation and a generous loan of ruthenium(III) chloride hydrate
from the Johnson Matthey Research Centre are grateful
acknowledged.
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