Highly efficient D2 generation by dehydrogenation of formic acid in D2O through H+/D+ exchange on an iridium catalyst: Application to the synthesis of deuterated compounds by transfer deuterogenation

Article abstract of DOI:10.1002/chem.201200576

Deuterated compounds have received increasing attention in both academia and industrial fields. However, preparations of these compounds are limited for both economic and practical reasons. Herein, convenient generation of deuterium gas (D₂) and the preparation of deuterated compounds on a laboratory scale are demonstrated by using a half-sandwich iridium complex with 4,4'-dihydroxy-2,2'-bipyridine. The "umpolung" (i.e., reversal of polarity) of a hydrogen atom of water was achieved in consecutive reactions, that is, a cationic H⁺/D⁺ exchange reaction and anionic hydride or deuteride transfer, under mild conditions. Selective D₂ evolution (purity up to 89%) was achieved by using HCO₂H as an electron source and D₂O as a deuterium source; a rhodium analogue provided HD gas (98%) under similar conditions. Furthermore, pressurized D ₂ (98%) without CO gas was generated by using DCO₂D in D₂O in a glass autoclave. Transfer deuterogenation of ketones gave α-deuterated alcohols with almost quantitative yields and high deuterium content by using HCO₂H in D₂O. Mechanistic studies show that the H⁺/D⁺ exchange reaction in the iridium hydride complex was much faster than β-elimination and hydride (deuteride) transfer. Cheap D₂ gas! Convenient generation of deuterium gas (D₂) and preparation of deuterated compounds on a laboratory scale are demonstrated using a half-sandwich iridium complex with 4,4'-dihydroxy-2,2'- bipyridine (see scheme). The "umpolung" of a hydrogen atom of water was achieved in consecutive reactions (cationic H⁺/D⁺ exchange reaction and anionic hydride (deuteride) transfer) under mild conditions. Copyright

Full text of DOI:10.1002/chem.201200576

FULL PAPER
DOI: 10.1002/chem.201200576
Highly Efficient D2 Generation by Dehydrogenation of Formic Acid in D2O
through H+/D+ Exchange on Iridium Catalyst: Application to the Synthesis
of Deuterated Compounds by Transfer Deuterogenation
Wan-Hui Wang,[a] Jonathan F. Hull,[b] James T. Muckerman,[b] Etsuko Fujita,[b]
Takuji Hirose,[c] and Yuichiro Himeda*[a]
Abstract: Deuterated compounds have
received increasing attention in both
academia and industrial fields. How-
reactions, that is, a cationic H+/D+ ex-
change reaction and anionic hydride or
deuteride transfer, under mild condi-
tions. Selective D2 evolution (purity up
to 89%) was achieved by using
HCO2H as an electron source and D2O
as a deuterium source; a rhodium ana-
logue provided HD gas (98%) under
similar conditions. Furthermore, pres-
surized D2 (98%) without CO gas was
generated by using DCO2D in D2O in
a glass autoclave. Transfer deuteroge-
nation of ketones gave a-deuterated al-
cohols with almost quantitative yields
and high deuterium content by using
HCO2H in D2O. Mechanistic studies
show that the H+/D+ exchange reac-
tion in the iridium hydride complex
was much faster than b-elimination and
hydride (deuteride) transfer.
ACHTUNGTRENNUNGever, preparations of these compounds
are limited for both economic and
practical reasons. Herein, convenient
generation of deuterium gas (D2) and
the preparation of deuterated com-
pounds on a laboratory scale are dem-
onstrated by using a half-sandwich iri-
dium complex with 4,4’-dihydroxy-2,2’-
bipyridine. The “umpolung” (i.e., re-
versal of polarity) of a hydrogen atom
of water was achieved in consecutive
Keywords: deuterium · isotopic ex-
change · iridium · reaction mecha-
nism · synthetic methods · umpo-
lung
Introduction
the preparation of chiral products using an asymmetric hy-
drogenation catalyst.[2] Although D2 can be produced by the
electrolysis of D2O on an industrial scale, commercially
available D2 gas is extremely expensive. Consequently, the
development of a convenient laboratory preparation of D2
gas (particularly pressurized D2 gas) is desirable.
Deuterium gas (D2) is one of the most useful and widely ap-
plicable reagents for the preparation of deuterated com-
pounds, which are widely used as research tools for the
study of reaction mechanisms and kinetics, drug metabolism,
and structural elucidation of biological molecules, etc.[1] Cat-
alytic deuterogenation using D2 offers universal and efficient
methods for preparing deuterated compounds by a proce-
dure similar to that used for hydrogenation. Unlike metal
deuterides (e.g., LiAlD4 and NaBD4), D2 can be applied to
Recently, there has been an increasing focus on H/D ex-
change reactions catalyzed by transition-metal complexes
because of the relevance of the reaction to the study of hy-
drogenase enzymes.[3] There have been many studies of H/D
exchange reactions in D2/H2O or H2/D2O systems catalyzed
by Ir, Rh, and Ru etc.[4] For example, Sajiki reported reduc-
tive deuterogenation by using D2 generated in situ by Pd/C-
catalyzed H/D exchange reaction in a H2/D2O system.[5] In
the dehydrogenation of formic acid in D2O, evolution of D2
through the H/D exchange reaction of a metal hydride inter-
mediate was observed. Puddephatt et al. reported that
a 1:2:1 mixture of H2, HD, and D2 gases was generated from
HCO2D/D2O or DCO2H/H2O catalyzed by a binuclear
ruthenium complex.[6] Fukuzumi et al. investigated the iso-
topic distribution of evolved hydrogen gas in the dehydro-
[a] Dr. W.-H. Wang, Dr. Y. Himeda
National Institute of Advanced
Industrial Science and Technology
Tsukuba Central 5-2, 1-1-1 Higashi
Tsukuba, Ibaraki 305-8565 (Japan)
E-mail: himeda.y@aist.go.jp
[b] Dr. J. F. Hull, Dr. J. T. Muckerman, Dr. E. Fujita
Chemistry Department
Brookhaven National Laboratory
Upton NY 11973 (USA)
genation of HCO2H in D2O catalyzed by [Cp*Rh
ACHTUNGTRENNUNG(bpy)-
[c] Prof. Dr. T. Hirose
Saitama University
G
E
R
ACHTUNGTRENNUNG
pyrimidine, bpy=2,2’-bipyridine).[7] Although a D2 content
of 40% was obtained with the latter catalyst, the reaction
rate was very slow due to the tunneling effect. Furthermore,
the rate of generating high purity D2 gas (95%) from
DCO2D in D2O was very slow.
255 Shimo-ohkubo
Sakura-ku, Saitama
Saitama 338–8570 (Japan)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201200576.
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
1
&
ÞÞ
These are not the final page numbers!

Alternative routes for the preparation of deuterated com-
pounds by the catalytic H/D exchange of unlabeled com-
pounds with a deuterated solvent have been widely investi-
gated recently in terms of time- and cost-efficiency.[8] In par-
ticular, D2O is the most attractive deuterium source because
of its low cost and toxicity.[9] However, H/D exchange reac-
tions are often limited to aromatic compounds and activated
positions; such reactions also require high catalyst loading
and harsh conditions. Consequently, most of the reactions
result in reduced selectivity or multiple deuteration.
Results and Discussion
Evolution of D2 by dehydrogenation of formic acid in D2O:
In an effort to develop clean energy sources, the past five
years have seen a significant focus on generating H2 from
formic acid as a hydrogen storage material using transition-
metal catalysts (Scheme 1, [Eq. (1)]).[13] Although many
In studies on the mechanism of catalytic hydrogenation in
D2O, reductions of a,b-unsaturated carboxylic acids and
esters afforded the corresponding a-monodeuterated car-
boxylic acids and esters that contain 85 and 75% deuterium,
respectively.[4d,9c] These studies concluded that deuterium in-
corporation occurred through an H/D exchange in the inter-
mediate s-alkylrhodium hydride and subsequent transfer of
deuterium from the metal to the a-carbon through a dihy-
dride mechanism; in other words, D incorporation occurred
through the addition of a net deuteron (D+). Very recently,
Kawashima et al. reported the stoichiometric and stepwise
deuteride reduction of carbonyl compounds using hexacoor-
dinated dideuterated phosphate, which was generated by H/
D exchange of the corresponding dihydridephosphate in
D2O.[10] It is intriguing that the reaction provides a deuteride
ion (DÀ) through the “umpolung” of a deuteron (D+) of
D2O. However, to the best of our knowledge, there is no ex-
ample of catalytic deuterogenation using a metal deuteride
([M]-D) generated by the “umpolung” of a D+ of D2O be-
cause it is difficult for metal deuteride to exhibit the two op-
posite properties, cationic exchange and anionic reduction.
We previously studied aqueous catalysis using half-sand-
wich iridium, rhodium, and ruthenium complexes with 4,4’-
dihydroxy-2,2’-bipyridine (DHBP) for hydrogenation of
CO2, dehydrogenation of formic acid, and transfer hydroge-
nation.[11] These catalysts exhibited similar catalytic perfor-
mance. However, in the hydrogenation of a,b-unsaturated
carboxylic acid using H2 in D2O, different products were ob-
tained with iridium and rhodium complexes.[12] The rhodium
catalyst gave a monodeuterated product, which was the
same product produced in Jooꢁs study,[4d] whereas the iridi-
um catalyst gave an unusual dideuterated product. These re-
sults imply that the hydrogen atom on an iridium metal
center acts as an active anionic hydride, and is exchangeable
with a protonic deuteron of D2O, resulting in the “umpo-
lung” of a hydrogen and deuteron atom. To the best of our
knowledge, this is the first example of homogeneous catalyt-
ic deuterogenation using H2 in D2O occurring through an
H+/D+ exchange reaction. As an extension of the study,
herein, we report a convenient and inexpensive method for
producing pressurized D2 or HD gas for laboratory use with
formic acid and D2O. In addition, further details regarding
the transfer deuterogenation of carbonyl compounds with
almost quantitative yields and high deuterium content are
presented. Moreover, we provide insight into the different
reaction mechanisms operating with the iridium, rhodium,
and ruthenium complexes.
Scheme 1. Generation of H2/HD/D2 gas from formic acid.
studies on homogeneous dehydrogenation of formate with
amine additives have been reported,[14] efficient catalysis in
aqueous media without organic additives are limited.[7,15] We
have reported the highly efficient dehydrogenation of
formic acid in H2O using catalysts with a water-soluble
DHBP ligand.[11a,c] Based on this work, we studied the iso-
topic distribution in the catalytic dehydrogenation using
[D2]formic acid/formic acid and D2O/H2O (Scheme 1,
[Eq. (2)]).
Initially, the dehydrogenation of formic acid in D2O using
the iridium-DHBP catalyst
1 ([Cp*IrACHTNUGTRNEG(NU OH2)AHCTUTGNENRNUG(LH2)]ACHTUNGTRENNUNG(SO4);
LH2: 4,4’-dihydroxy-2,2’-bipyridine; Scheme 1) was investi-
gated (Table 1). As we previously reported, dehydrogena-
tion of formic acid in H2O showed a high turnover frequen-
cy (TOF) of 2400 hÀ1 under standard conditions (Table 1,
entry 1). In contrast, the reaction in D2O under the same
conditions gave a lower TOF of 1140 hÀ1 due to the deuteri-
um kinetic isotope effect (KIE). The evolved gas mixture
was analyzed by GC using a thermal conductivity detector
(TCD). We found D2 gas was generated in high selectivity
of 86% with a small amount of HD (14%) (Table 1,
entry 2; also see the Supporting Information, Figure S1).
Similar to the reaction in H2O, CO (<10 ppm) was unde-
tected in the evolved gas by GC analysis using a methanizer
and a flame ionization detector (FID). At the end of the re-
action, approximately 500 mL of gas mixture (H2, HD, D2,
and CO2) was evolved. This indicates complete conversion
of formic acid, which was further confirmed by HPLC analy-
sis.
The influence of the reaction conditions on the D2 content
of the evolved gas was examined. The D2 content was only
slightly affected by the reaction temperature (Table 1, en-
tries 2–4). A high selectivity of 89% was obtained at 408C
&
2
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Highly Efficient D2 Generation
FULL PAPER
Table 1. Isotope distribution for evolved hydrogen gas in the dehydro-
genation of formic acid/formate in H2O or D2O.[a]
Entry Catalyst Substrate Solvent TOF[b]
[mmol]
[hÀ1
Fraction [mol%][c]
H2 HD D2
N
N
]
1
2
3
4
5
6
7
8
1 (2)
1 (2)
1 (2)
1 (2)
2 (2)
4 (4)
1 (2)
1 (2)
5 (4)
5 (4)
5 (4)
5 (4)
5 (4)
6 (10)
6 (10)
6 (10)
6 (10)
HCO2H
HCO2H
HCO2H
HCO2H
HCO2H
HCO2H
DCO2D
DCO2D
H2O
D2O
D2O[f]
D2O[g]
D2O
D2O
H2O
D2O
D2O
H2O
D2O
H2O
D2O
H2O
D2O
H2O
D2O
2400
1140
170
4550
450
11
1660
940
340
1070
1000
330
330
80
100
0
n.d. 11
1
0
0
82
n.d.
5
–
5
2
–
–
0
71
–
0
14
0
86
89
82
88
89
0
98
4
–
17
12
11
18
2
91
–
89
98
–
9
HCO2H
[d]
10
11
12
13
14
15
16
17
[d]
[e]
[e]
[d]
[d]
[e]
[e]
6
0
–
–
–
80
36
39
16
29
–
84
n.d.
–
[a] The reaction was carried out in a deaerated 1m aqueous formic acid/
formate solution (10 mL) at 608C. [b] Initial TOF. [c] Analysis by GC;
the numbers are rounded; n.d.: not detected. [d] The substrate was
HCO2H/HCO2Na (9:1). [e] The substrate was DCO2D/DCO2Na (9:1).
[f] At 408C. [g] At 808C.
(Table 1, entry 3). We also found that the D2 selectivity was
independent of catalyst concentration. An increase in the
concentration of formic acid in D2O led to a decrease in the
percentage of D2 (see the Supporting Information, Fig-
ure S2), which could be attributed to the increase in the H
content of the entire reaction system. Previously, we report-
ed that the TOF values and the conversion of formic acid
were strongly dependent on the pH of the reaction solu-
tion.[11c] Thus, the pH dependence of the composition of the
evolved gases was investigated by changing the ratio of
HCO2H to HCO2Na. An increase in the HCO2Na content
in the substrate led to a significant decrease in TOF and
a proportionate decrease in the amount of evolved gas, as
well as to a slight decrease in the percentage of D2 (Fig-
ure 1a). The electronic substituent effect on the selectivity
and reaction rate was also investigated. Consistent with our
previous studies, the catalytic reactivity decreased in the
order 1 (R=OH) > 2 (R=OMe) > 3 (R=Me) > 4 (R=H)
(Table 1, entries 2, 5, and 6). A good linear correlation was
observed in the Hammett plot (see the Supporting Informa-
tion, Figure S3). Using 2 and 4, however, a slight increase in
selectivity was observed. When DCO2D/H2O was used, H2
was mainly formed in a purity of 82%, with 18% HD. The
relatively high TOF value (1660 hÀ1) suggests that its KIE
value was lower than that of dehydrogenation using
HCO2H/D2O (Table 1, entry 7 vs. 2). As expected, the reac-
tion of DCO2D in D2O produced high purity D2 (98%) with
a satisfactory TOF of 940 hÀ1 (Table 1, entry 8). The results
indicate that the evolved isotopic hydrogen gas came princi-
pally from the solvent through a rapid H/D exchange be-
tween [Ir-H] (or [Ir-D]) and the solvent.
Figure 1. Dependence of the fraction of the evolved hydrogen gas on the
ratio of HCO2H/HCO2Na (CHCO H +CHCO Na =1) in the dehydrogenation
2
2
of 1m formic acid/formate in D2O at 608C catalyzed by: a) iridium-
DHBP catalyst 1 (0.2 mm), and b) rhodium-DHBP catalyst 5 (0.4 mm).
ieved. The reaction was carried out using 2m DCO2D in
D2O at 808C in a glass autoclave. Similar to the reaction
system of HCO2H/H2O, the total pressure of a CO-free gas
mixture reached 4.9 MPa (see the Supporting Information,
Figure S4). Hence, high pressure and purity of D2 (97%)
was obtained. Note that the high pressure had almost no in-
hibitory influence on the dehydrogenation of formic acid.
At the end of the reaction, only 2.4% of DCO2D (48 mm)
remained in the solution. Additionally, the reaction using
2m HCO2H in D2O could provide a total pressure of
5.0 MPa and albeit with a lower purity of D2 (77%).
Interestingly, the use of the rhodium analogue 5 led to
completely different results. Because the presence of for-
mate resulted in a significant increase in the reaction rate
for 5 (Table 1, entry 9 vs. 11) and 6,[11a] the reaction was car-
ried out in formic acid/formate (9:1) in water (D2O or
H2O). The reactions of both HCO2H/HCO2Na in D2O
(Table 1, entry 11) and DCO2D/DCO2Na in H2O (Table 1,
entry 12) produced high purity HD gas. A KIE of 3.2 was
observed only in the reaction using DCO2D/DCO2Na in
H2O, whereas the TOF of the reaction of HCO2H/HCO2Na
in D2O showed no decrease (KIE=1.1). The TOF of the re-
action using DCO2D/DCO2Na in D2O (Table 1, entry 13)
was the same as that measured using H2O (Table 1,
entry 12). These results are consistent with the isotopic
effect observed in the transfer hydrogenation of NAD+
Using the highly active iridium catalyst 1, the convenient
and cost-effective production of pressurized D2 gas was ach-
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
3
&
ÞÞ
These are not the final page numbers!

Y. Himeda et al.
using the unsubstituted bipyridine rhodium analogue
[Cp*Rh
(bpy)Cl]+.[16]
spray ionization mass spectra (ESI-MS) of the deuterated
products in the H2O phase showed peaks at m/z 132
[M(D1)-H]À (11–17%), 133 [M(D2)-H]À (100%), and 134
[M(D3)-H]À (12–22%; see the Supporting Information, Fig-
ure S6). These results clearly indicate that two deuterium
atoms are incorporated into the C=C double bonds in the
catalytic reaction with 1.
ACHTUNGTRENNUNG
The ruthenium analogue 6 showed poor catalytic activity
in the dehydrogenation (Table 1, entries 14–17). The trend
of KIEs of 6 was similar to that of the rhodium catalyst 5,
whereas the gas fractions were similar to those obtained
using iridium catalyst 1.
Generally, transfer hydrogenation in water using formic
acid as a hydrogen donor is faster, safer, and operationally
simpler than hydrogenation. The transfer hydrogenation of
itaconic acid in D2O was investigated with 1 and 5 (Table 2).
Preparation of deuterated compounds by transfer deutero-
genation in D2O: The interesting properties described above
can be applied to the preparation of deuterated compounds.
In our preliminary study,[12] we demonstrated hydrogenation
of itaconic acid and citraconic acid in D2O at 508C under
1 MPa of H2 by iridium catalyst 1. Figure 2a shows the
Table 2. Transfer hydrogenation (deuterogenation) of itaconic acid using
1 and 5.
Entry
Catalyst
Reductant
Solvent
Yield
[%]
D content [%][c]
C2
C3
1
2
3
4
1
1
5
5
HCO2H[a]
DCO2D[b]
HCO2H[a]
DCO2D[b]
D2O
H2O
D2O
H2O
>99
76
>99
56
93
6
93
8
102
24
8
107
[a] The reaction was carried out with itaconic acid (0.5 mmol) and a cata-
lyst (2 mmol) at 508C in a degassed 1.25m solution of HCO2H in D2O
(4 mL) for 24 h. [b] The reaction was carried out with itaconic acid
(0.5 mmol) and a catalyst (2 mmol) at 508C in a degassed 0.53m solution
of DCO2D in H2O (10 mL) for 17 h. [c] The deuterium content of the
product was determined by 1H NMR spectroscopic analysis on the basis
of the integration.
Using 1 and HCO2H in D2O, itaconic acid was almost quan-
titatively transformed into 2,3-dideuterated methylsuccinic
acid with efficient incorporation of deuterium (Table 2,
entry 1). In contrast, the reaction using DCO2D in H2O
gave methylsuccinic acid with low D content, 6 and 24% at
C-2 and C-3, respectively (Table 2, entry 2). Thus, it was
clarified that the incorporated H or D atoms in the reaction
were mainly derived from the solvent. This result is consis-
tent with our previously reported mechanism of deuteroge-
nation.[12] The iridium hydride ([Ir-H]) generated from dehy-
drogenation of HCO2H will go through quick H/D exchange
with a deuteron of D2O, resulting in an iridium deuteride
([Ir-D]). This transfers the anionic deuteride to the C-3 posi-
tion of the substrate. Following external deuteration at C-2
with D+ from D2O, the dideuterated product is formed. In
the DCO2D/H2O system, similarly, the active species [Ir-D]
generated from dehydrogenation of DCO2D will undergo
H/D exchange with solvent H2O and therefore give low D
content. On the other hand, the reactions catalyzed by rho-
dium catalyst 5 gave a C-2 monodeuterated product in
HCO2H/D2O (Table 2, entry 3 and Figure 3b) and a C-3
monodeuterated product in DCO2D/H2O (Table 2, entry 4
and Figure 3a). These results suggest that [Rh-H] transfers
the hydride to C-3 and that solvent D2O provides the deu-
teron at C-2 position in the HCO2H/D2O system, whereas
[Rh-D] transfers the deuteride to C-3 and solvent H2O de-
livers the hydrogen to C-2 in the DCO2D/H2O system. It is
clear that [Rh-H] or [Rh-D] involves no H/D exchange,
Figure 2. NMR spectra of methylsuccinic acid from hydrogenation using
iridium catalyst 1: a) 1H NMR spectrum from reaction with itaconic acid
in H2O; b) 1H NMR and c) 2H NMR spectra from the reaction with ita-
conic acid in D2O; d) 1H NMR spectrum from reaction with citraconic
acid in D2O.
1H NMR spectrum of methylsuccinic acid produced from
1
itaconic acid in H2O. The H NMR spectrum of the product
generated from itaconic acid in D2O shows the disappear-
ance of two protons at the 2- and 3-positions (Figure 2b).
2
The H NMR spectrum in Figure 2c shows that two deuteri-
um atoms were incorporated at the 2- and 3-positions. In
the proton-decoupled 13C NMR spectrum, two triplets of the
2- and 3-carbon were observed at d=18.8 and 38.6 ppm, re-
spectively (see the Supporting Information, Figure S5).[17]
These results showed that the hydrogenation in D2O gave
2,3-dideuterated methylsuccinic acid. In addition, the hydro-
genation of citraconic acid in D2O led to the production of
1,2-dideuterated methylsuccinic acid in 99% yield, as deter-
mined by 1H NMR (Figure 2d) and proton-decoupled
13C NMR spectroscopic analyses. The negative-ion electro-
&
4
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Highly Efficient D2 Generation
FULL PAPER
content (see the Supporting Information, Figure S7). An in-
crease in the reaction temperature led to a slight increase in
the deuterium content (see the Supporting Information, Fig-
ure S8). In addition to cyclic ketones, aliphatic and aromatic
ketones could also be transformed into a-deuterated alco-
hols with high deuterium content (Table 3, entries 6–8). In
the case of the reactive benzaldehyde (Table 3, entry 16),
the corresponding product contained almost no deuterium,
although it was obtained in quantitative yield. We conclude
that substrates with lower reactivity lead to products with
higher deuterium content.
Reusability of the catalytic system was tested by carrying
out consecutive cycles for cycloheptanone (Table 3, en-
tries 3–5), o-Cl
ACHTUGNERTN(NUGN C6H4)COMe (Table 3, entries 9–11), and p-
Cl(C6H4)COMe (Table 3, entries 12–15) in D2O. The prod-
AHCTUNGTRENNUNG
ucts were carefully extracted with hexane and separated
from the water phase at the end of each run. After each cat-
alytic reaction, formic acid (2 mmol) and substrate
(0.5 mmol) were added without further addition of catalyst
and D2O. Although the reaction yields remained almost the
same, there was a slight decrease in the deuterium content
of the product due to the decrease in the ratio of deuterium
to protium.
Figure 3. 1H NMR spectra of methylsuccinic acid from a reaction of ita-
conic acid catalyzed by rhodium catalyst 5 using: a) DCO2D in H2O and
b) HCO2H in D2O.
which is in agreement with our study on the dehydrogena-
tion of formic acid (see mechanism below).
The transfer deuterogenation of a range of water-soluble
and water-insoluble ketones using iridium catalyst 1 was ex-
amined (Table 3). The reaction of cyclic ketones gave the
corresponding a-deuterated alcohols in almost quantitative
yields with high deuterium content. Less reactive cyclopen-
tanone and cycloheptanone showed slightly higher deuteri-
um content than cyclohexanone (Table 3, entries 1 and 3 vs.
2). The deuterium content of the product was investigated
under various reaction conditions. The concentration of
HCO2H (0.2–0.8m) had almost no effect on the deuterium
Detection of an iridium-deuteride intermediate: Metal hy-
dride (M-H) complexes are known to be active species in
hydrogenation and transfer hydrogenation. In fact, several
iridium hydride complexes have been either isolated[18] or
detected.[11e] The active species generated from the reaction
of 1 {[Cp*Ir
H2O/D2O were analyzed by positive-ion ESI-MS. The
normal iridium hydride complex [Cp*Ir-H
(LH2)]+ (M+ =
ACTHUGNNERTU(GNN OH2)ACHTUNRTGE(NGNUN LH2)]CAHTNGURTNEN(GUN SO4)} under 1 MPa of H2/D2 in
AHCTUNGTRENNUNG
517) was detected from the reaction of 1 with H2 in H2O
(Figure 4a), whereas the reaction of 1 with H2 in D2O under
neutral conditions afforded the O-deuterated hy-
dride [Cp*Ir-HACTHNUTRGNEUNG
(LD2)]+ (M+ =519) (Figure 4b).
Moreover, the species in D2O under acidic condi-
tions (pD=2.7) showed M+ =520, which corre-
sponds to O-deuterated iridium deuteride [Cp*Ir-
Table 3. Transfer deuterogenation of ketones to a-deuterated alcohols catalyzed by
1 in a sealed tube.[a]
Entry
Substrate
Time
[h]
Amount
Yield
[%]
D content
[%][b]
DACTHNUTRGNEUNG
(LD2)]+ (Figure 4c). These results suggest that,
of 1 [mmol]
under acidic conditions in water, cationic H in iridi-
um hydride undergoes a rapid H+/D+ exchange
with cationic D in the solvent and consequently
forms an iridium deuteride species.[18]
1
2
3
4
5
6
7
8
cyclopentanone
cyclohexanone
cycloheptanone
cycloheptanone
cycloheptanone
acetone
36[c]
20[d]
20
36
48
2.5
0.5
1.0
98
>99
>99
>99
98
92
74
85
80
75
91
86
73
87
84
81
81
80
78
74
n.d.
(Recycle 2)[e]
(Recycle 3)[e]
2.0
24
96
99
Proposed reaction path: We propose a reaction
path for the dehydrogenation of formic acid in
water as shown in Figure 5. The reaction of the
complex with formic acid gives the metal hydride
(deuteride) [M-H(D)] through b-hydrogen elimina-
tion in the corresponding formate complex [M-
OC(=O)H] (Figure 5, Path a). Depending on the
metal, an H+/D+ exchange reaction can, in some
cases, proceed (Figure 5, Path b). Finally, the [M-
H(D)] reacts with H+ or D+ to give three kinds of
isotopic hydrogen gas (H2, HD, and D2). Table 4
summarizes the KIE values and reaction paths of
3-methyl-2-butanone
acetophenone
48[c]
24
2.0
2.0
2.0
>99
>99
>99
94
>99
>99
98
9
o-Cl
o-Cl
o-Cl
p-Cl
p-Cl
p-Cl
p-Cl
N
48
64
40
48
64
48
48
8
10
11
12
13
14
15
16
(Recycle 2)[e]
(Recycle 3)[e]
2.0
(Recycle 2)[e]
(Recycle 3)[e]
(Recycle 4)[e]
1.0
97
>99
benzaldehyde
[a] The reaction was carried out using the substrate (0.5 mmol) and the desired
amount of 1 at 508C in a degassed 0.4m solution of HCO2H in D2O (5 mL). [b] D con-
tent was determined by 1H NMR spectroscopic analysis. [c] Using 0.8m HCO2H solu-
tion. [d] Using 0.2m HCO2H solution. [e] Recycling of catalyst.
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
5
&
ÞÞ
These are not the final page numbers!

Y. Himeda et al.
On the other hand, the generation of HD using rhodium
catalyst 5 may proceed through different pathways without
an H+/D+ exchange reaction (Path b). The paths of the re-
action involving rhodium catalyst 5 in HCO2H/D2O and
DCO2D/H2O may go through a(H)-c(HD) and a(D)-c(DH),
respectively. The paths of ruthenium catalyst 6 should be
the same as those of 1.
The trends of the KIE values obtained upon changing the
substrate and solvent are the same for catalysts 5 and 6.
Using the same substrate HCO2H/HCO2Na or DCO2D/
DCO2Na, the rates of gas production were almost the same
when the solvent was changed from H2O to D2O (Table 1,
entries 9–16 and Table 4). On the other hand, the KIEs for
the reactions of DCO2D/DCO2Na in H2O or D2O are larger
than those for the reactions of HCO2H/HCO2Na in D2O
(Table 4). These results clearly indicate that the rate-deter-
mining steps in the dehydrogenation catalyzed by 5 and 6
are those of Path a. Note that H+/D+ exchange must have
occurred for ruthenium catalyst 6 because of the major gen-
eration of D2 from D2O and H2 from H2O (Table 1, en-
tries 14 and 15); whereas the exchange was unfavorable for
rhodium catalyst 5, for which HD was mainly generated
from either DCO2D/H2O or HCO2H/D2O (Table 1, en-
tries 10 and 11).
Figure 4. Positive-ion ESI-MS (direct injection) of: a) the hydride
[Cp*Ir-H
(LH2)]+ generated in H2O; b) the O-deuterated hydride
[Cp*Ir-H
(LD2)]+ generated in D2O; and c) the O-deuterated deuteride
[Cp*Ir-D
(LD2)]+ generated in D2O (pD=2.7). Bar graph depicts calcu-
G
ACHTUNGTRENNUNG
E
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
lated isotopic distribution.
The trends of KIE values for iridium catalyst 1 were dif-
ferent from those of 5 and 6. In fact, the Arrhenius plots
shown in Figure S9 (the Supporting Information), give acti-
vation energies of 76 (for HCO2H/H2O), 82 (for HCO2H/
D2O), 79 (for DCO2D/H2O), and 86 kJmolÀ1 (for DCO2D/
D2O). The rate of production of H2 from DCO2D/H2O
(KIE: 1.4) was slightly lower than that from HCO2H/H2O.
But the KIE for HCO2H/D2O (2.1) was larger than that for
DCO2D/H2O (Table 4). This result suggests that formation
of [Ir-H] or [Ir-D] is less likely to be the rate-determining
step. Moreover, the KIE of the DCO2D/D2O system (2.6) is
larger than that of HCO2H/D2O (2.1), which indicates that
the rate of the H+/D+ ex-
Figure 5. Proposed reaction paths for the dehydrogenation of formic acid
in water ([M-Y]: complexes 1, 5, and 6; M: Ir, Rh, Ru).
change reaction (Path b) is very
Table 4. KIE and reaction path for the dehydrogenation of formic acid/formate in water.
fast and that the rate-determin-
ing step may be Path c. Addi-
tionally, in contrast to Fukuzu-
miꢁs report, our catalytic sys-
tems showed no tunneling ef-
fects.[7b]
Catalyst
1
5[a]
6[a]
Substrate Solvent KIE Gas Path
KIE Gas Path
KIE Gas Path
HCO2H H2O
HCO2H D2O
DCO2D H2O
DCO2D D2O
–
H2 a(H)-c(HH)
D2 a(H)-b(D)-c(DD) 1.1
H2 a(D)-b(H)-c(HH) 3.2
–
H2 a(H)-c(HH)
–
HD a(H)-c(HD) 1.0
HD a(D)-c(DH) 2.2
D2 a(D)-c(DD) 2.1
H2 a(H)-c(HH)
2.1
1.4
2.6
D2 a(H)-b(D)-c(DD)
H2 a(D)-b(H)-c(HH)
D2 a(D)-c(DD)
D2 a(D)-c(DD)
3.2
The ordering of the reaction
rate constants for each reaction
path using 1, 5, and 6 are sum-
marized as follows:
[a] The substrates were HCO2H/HCO2Na (9:1) or DCO2D/DCO2Na (9:1) for 5 and 6.
the dehydrogenation catalyzed by different metal com-
plexes. The supposed reaction paths of iridium catalyst 1 in
HCO2H/D2O are as follows: 1) Path a(H), generation of [Ir-
H]; 2) Path b(D), generation of [Ir-D] by the very fast H+
/D+ exchange reaction and “umpolung”; and 3) Path c(DD),
reaction of [Ir-D] with D+ to give D2. The reaction using
DCO2D/H2O may go through Path a(D)-b(H)-c(HH). Note
that iridium catalyst 1 should undergo a very fast H+/D+ ex-
change reaction in Path b because HCO2H/D2O mainly gave
D2 and DCO2D/H2O mainly generated H2.
iridium catalyst 1: kb >ka >[kc]
rhodium catalyst 5: kc >[ka]@kb
ruthenium catalyst 6: kb >kc >[ka]
The rate constants in square brackets are proposed to corre-
spond to the rate-determining steps on the basis of our
&
6
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Highly Efficient D2 Generation
FULL PAPER
meter reading + 0.4). D2O (99.9%), DCO2D in D2O (98%) were pur-
chased from Aldrich. Reference gas of HD (HD: 97%, H2: 1.8%, D2:
1.2%; Isotec Inc.) and D2 (D2 19.3% in He; GL Science) were obtained
from commercial source. The complexes 1–6 were prepared according to
the literature.[11d,12]
study of KIEs. It has been found that the isoelectronic cata-
lysts 1, 5, and 6 exhibit similar catalytic performance in hy-
drogenation, transfer hydrogenation, and dehydrogenation,
etc. However, we observed that they showed different prop-
erties in each elementary step in the dehydrogenation of
formic acid. The rate-determining steps of 5 and 6 are the
formation of the metal-hydride complex (Path a), which is
consistent with the observation in the transfer hydrogena-
tion using formic acid catalyzed by a rhodium analogue.[16]
In contrast, for iridium catalyst 1, the rate-determining step
should be the reaction of the metal hydride (deuteride) with
a proton (deuteron). The H+/D+ exchange reaction (Path b)
is rapid for 1 and 6, but very slow in the case of 5. The over-
all reaction rate decreased in the order 1> 5@ 6.
Typical procedure for dehydrogenation of formic acid/formate in water
(H2O or D2O): A solution of catalyst (20 mm, 100 mL, 2 mmol) was added
to a deaerated aqueous solution of formic acid/formate (1 m, 10 mL), and
the mixture was stirred at the desired temperature. The volume of gas
evolved was determined by a gas meter (Shinagawa Corp., W-NK-05).
The initial TOF was calculated by using linear least-squares fitting of the
experimental data obtained from the initial part of the reaction, after
a short induction period.
General procedure for deuterogenation: A solution of catalyst (3 mmol)
in D2O (0.5 mL) was added to a solution of substrate (0.5 mmol) in D2O
(5 mL). The reaction was stirred at 508C under 1 MPa of H2. The yield
was analyzed by GC (PEG-HT 5%, Uniport HT 60/80, 2 m packed
column, 1008C) or HPLC (Tosoh TSKgelSCX(H+)). The ratios of deute-
1
rium incorporation were analyzed by H NMR spectroscopy.
Conclusion
General procedure for transfer deuterogenation: To a degassed D2O
(5 mL) solution of HCO2H (0.4 m) and substrate (0.5 mmol) was added
a D2O solution (0.5 mL) of the catalyst (2 mmol). The reaction was car-
ried out at 508C in a sealed tube. The reaction solution was analyzed by
GC (PEG-HT 5%, Uniport HT 60/80 2 m packed column) and 1H NMR
spectroscopy.
We have demonstrated a simple and efficient method for D2
generation and the preparation of deuterated compounds
catalyzed by iridium catalyst 1. By using D2O as a deuterium
source, dehydrogenation of formic acid generated high
purity, pressurized D2 gas; the transfer deuterogenation pro-
duced deuterated compounds with high deuterium content.
The effective catalysis is attributed to the “umpolung” of
a deuterium atom of D2O through a rapid H+/D+ exchange
with the iridium catalyst. To the best of our knowledge, this
is the first example of the production of deuterated com-
pounds through complex-catalyzed transfer deuterogenation
based on the “umpolung” of a deuterium atom of D2O. The
catalytic system is expected to be useful for the preparation
of D2 gas and deuterium compounds on a laboratory scale.
It was found that the iridium, rhodium, and ruthenium
catalysts showed different kinetic properties in these reac-
tions. D2 and HD gas can be selectively generated by using
iridium catalyst 1 and rhodium catalyst 5, respectively.
These studies, which show that selective hydrogen genera-
tion is dependent on the metal in the complex, might also
allow a better understanding of hydrogenase enzymes.
Procedure for catalytic recycling for transfer hydrogenation: To a de-
gassed D2O solution of HCO2H (2 mmol) and substrate (0.5 mmol) was
added a D2O solution of the catalyst. The reaction was carried out at
508C in a sealed tube. The resulting solution was extracted with hexane
six times. The product was analyzed by GC and 1H NMR spectroscopy.
To the aqueous solution was added HCO2H (2 mmol) and substrate
(0.5 mmol). The next run was carried out under the same reaction condi-
tions.
Acknowledgements
We thank the Japanese Ministry of Economy, Trade, and Industry for
providing financial support. The research at Brookhaven National Labo-
ratory was carried out under contract DE-AC02–98CH10884 with the U.
S. Department of Energy and supported by the Office of Basic Energy
Sciences. J. F. H. gratefully acknowledges a BNL Goldhaber Distinguish-
ed Fellowship.
[1] a) T. Junk, W. J. Catallo, Chem. Soc. Rev. 1997, 26, 401–406; b) J.
Atzrodt, V. Derdau, T. Fey, J. Zimmermann, Angew. Chem. 2007,
119, 7890–7911; Angew. Chem. Int. Ed. 2007, 46, 7744–7765.
[2] G. Hou, F. Gosselin, W. Li, J. C. McWilliams, Y. Sun, M. Weisel,
P. D. OꢁShea, C.-Y. Chen, I. W. Davies, X.-M. Zhang, J. Am. Chem.
Soc. 2009, 131, 9882–9883.
[3] a) P. M. Vignais, Coord. Chem. Rev. 2005, 249, 1677–1690; b) D. J.
Evans, C. J. Pickett, Chem. Soc. Rev. 2003, 32, 268–275; c) G. J.
Kubas, Chem. Rev. 2007, 107, 4152–4205; d) N. Wang, M. Wang, J.
Liu, K. Jin, L. Chen, L. Sun, Inorg. Chem. 2009, 48, 11551–11558;
e) C. Mealli, T. B. Rauchfuss, Angew. Chem. 2007, 119, 9100–9102;
Angew. Chem. Int. Ed. 2007, 46, 8942–8944.
[4] a) J. L. Carriker, P. S. Wagenknecht, M. A. Hosseini, P. E. Fleming,
J. Mol. Catal. A 2007, 267, 218–223; b) P. V. Grundler, O. V. Yazyev,
N. Aebischer, L. Helm, G. Laurenczy, A. E. Merbach, Inorg. Chim.
Acta 2006, 359, 1795–1806; c) F. A. Jalꢂn, B. R. Manzano, A. Cabal-
lero, M. C. Carrion, L. Santos, G. Espino, M. Moreno, J. Am. Chem.
Soc. 2005, 127, 15364–15365; d) G. Kovꢃcs, L. Nadasdi, G. Laurenc-
zy, F. Joꢂ, Green Chem. 2003, 5, 213–217; e) A. Azua, S. Sanz, E.
Peris, Chem. Eur. J. 2011, 17, 3963–3967.
Experimental Section
All manipulations were carried out under an argon atmosphere using
standard Schlenk techniques. All aqueous solutions were degassed prior
to use. 1H and 13C NMR were recorded with a Varian INOVA 400 spec-
trometer using tetramethylsilane (TMS) or sodium 3-(trimethylsilyl)-1-
propanesulfonate (DSS) as internal standard. The formate concentrations
were monitored by HPLC analysis with an anion-exclusion column
[Tosoh TSKgel SCX(H+)] using aqueous phosphate solution (20 mm) as
eluent and a UV detector (l=210 nm). CO2 and CO gases were analyzed
with an FID equipped with a methanizer using a Porapak Q 80/100 at
508C, on a GL Science GC390 gas chromatograph. H2, HD, and D2 gases
were analyzed with a TCD (1508C, 60 mA) on a GL Science GC390 gas
chromatograph [Ne carrier, Hydro Isopack (2.0 m, 4.0 mm i.d., GTR
TEC Co., Ltd.) at 77 K (liquid N2)].[19] The pressure in the reactor was
measured by a digital pressure gauge (NAGANO KEIKI Co., LTD.
GC64). The pH values were measured with an Orion 3-Star pH meter
with a glass electrode after calibration to standard buffer solutions. The
pD values were corrected by adding 0.4 to the observed values (pD=pH
[5] a) H. Sajiki, T. Kurita, H. Esaki, F. Aoki, T. Maegawa, K. Hirota,
Org. Lett. 2004, 6, 3521–3523; b) T. Kurita, F. Aoki, T. Mizumoto, T.
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
7
&
ÞÞ
These are not the final page numbers!

Y. Himeda et al.
Maejima, H. Esaki, T. Maegawa, Y. Monguchi, H. Sajiki, Chem.
Eur. J. 2008, 14, 3371–3379.
[6] Y. Gao, J. K. Kuncheria, H. A. Jenkins, R. J. Puddephatt, G. P. A.
Yap, J. Chem. Soc. Dalton Trans. 2000, 3212–3217.
[7] a) S. Fukuzumi, T. Kobayashi, T. Suenobu, ChemSusChem 2008, 1,
827–834; b) S. Fukuzumi, T. Kobayashi, T. Suenobu, J. Am. Chem.
Soc. 2010, 132, 1496–1497.
2022; d) Y. Himeda, N. Onozawa-Komatsuzaki, S. Miyazawa, H. Su-
gihara, T. Hirose, K. Kasuga, Chem. Eur. J. 2008, 14, 11076–11081;
e) Y. Himeda, N. Onozawa-Komatsuzaki, H. Sugihara, K. Kasuga,
Organometallics 2007, 26, 702–712; f) Y. Himeda, Eur. J. Inorg.
Chem. 2007, 3927–3941; g) Y. Himeda, N. Onozawa-Komatsuzaki,
H. Sugihara, H. Arakawa, K. Kasuga, Organometallics 2004, 23,
1480–1483; h) Y. Himeda, N. Onozawa-Komatsuzaki, H. Sugihara,
H. Arakawa, K. Kasuga, J. Mol. Catal. A 2003, 195, 95–100.
[12] Y. Himeda, S. Miyazawa, N. Onozawa-Komatsuzaki, T. Hirose, K.
Kasuga, Dalton Trans. 2009, 6286–6288.
[13] a) B. Loges, A. Boddien, F. Gartner, H. Junge, M. Beller, Top. Catal.
2010, 53, 902–914; b) S. Enthaler, J. von Langermann, T. Schmidt,
Energy Environ. Sci. 2010, 3, 1207–1217; c) T. C. Johnson, D. J.
Morris, M. Wills, Chem. Soc. Rev. 2010, 39, 81–88.
[14] a) B. Loges, A. Boddien, H. Junge, M. Beller, Angew. Chem. 2008,
120, 4026–4029; Angew. Chem. Int. Ed. 2008, 47, 3962–3965;
b) D. J. Morris, G. J. Clarkson, M. Wills, Organometallics 2009, 28,
4133–4140; c) R. Tanaka, M. Yamashita, L. W. Chung, K. Moroku-
ma, K. Nozaki, Organometallics 2011, 30, 6742–6750.
[15] C. Fellay, P. J. Dyson, G. Laurenczy, Angew. Chem. 2008, 120, 4030–
4032; Angew. Chem. Int. Ed. 2008, 47, 3966–3968.
[16] R. Ruppert, S. Herrmann, E. Steckhan, J. Chem. Soc. Chem.
Commun. 1988, 1150–1151.
[17] E. Papp, I. Banyai, F. Joꢂ, React. Kinet. Catal. Lett. 2000, 69, 23–30.
[18] T. Abura, S. Ogo, Y. Watanabe, S. Fukuzumi, J. Am. Chem. Soc.
2003, 125, 4149–4154.
[19] a) T. Kawano, N. Tsuboi, H. Tsujii, T. Sugiyama, Y. Asakura, T.
Uda, Jpn. J. Appl. Phys. 2–Lett. 2003, 42, L549–L551; b) T.
Kawano, N. Tsuboi, H. Tsujii, T. Sugiyama, Y. Asakura, T. Uda, J.
Chromatogr. A 2004, 1023, 123–127.
[8] a) C. M. Yung, M. B. Skaddan, R. G. Bergman, J. Am. Chem. Soc.
2004, 126, 13033–13043; b) J. A. Brown, S. Irvine, A. R. Kennedy,
W. J. Kerr, S. Andersson, G. N. Nilsson, Chem. Commun. 2008,
1115–1117; c) M. H. G. Prechtl, M. Holscher, Y. Ben-David, N.
Theyssen, R. Loschen, D. Milstein, W. Leitner, Angew. Chem. 2007,
119, 2319–2322; Angew. Chem. Int. Ed. 2007, 46, 2269–2272; d) R.
Corberꢃn, M. Sanau, E. Peris, J. Am. Chem. Soc. 2006, 128, 3974–
3979; e) J. R. Zhou, J. F. Hartwig, Angew. Chem. 2008, 120, 5867–
5871; Angew. Chem. Int. Ed. 2008, 47, 5783–5787.
[9] a) S. R. Klei, J. T. Golden, T. D. Tilley, R. G. Bergman, J. Am. Chem.
Soc. 2002, 124, 2092–2093; b) M. Takahashi, K. Oshima, S. Matsu-
bara, Chem. Lett. 2005, 34, 192–193; c) J. Bakos, R. Karaivanov, M.
Laghmari, D. Sinou, Organometallics 1994, 13, 2951–2956; d) T.
Maegawa, Y. Fujiwara, Y. Inagaki, Y. Monguchi, H. Sajiki, Adv.
Synth. Catal. 2008, 350, 2215–2218; e) G. Erdogan, D. B. Grotjahn,
J. Am. Chem. Soc. 2009, 131, 10354–10355; f) S. K. S. Tse, P. Xue,
C. W. S. Lau, H. H. Y. Sung, I. D. Williams, G. Jia, Chem. Eur. J.
2011, 17, 13918–13925.
[10] a) H. Miyake, N. Kano, T. Kawashima, Inorg. Chem. 2011, 50, 9083–
9089; b) H. Miyake, N. Kano, T. Kawashima, J. Am. Chem. Soc.
2009, 131, 16622–16623.
[11] a) Y. Himeda, S. Miyazawa, T. Hirose, ChemSusChem 2011, 4, 487–
493; b) Y. Himeda in Advances in CO2 Conversion and Utilization,
Vol. 1056 (Ed.: Y. H. Hu), American Chemical Society, Washington
DC, 2010, pp. 141–153; c) Y. Himeda, Green Chem. 2009, 11, 2018–
Received: February 22, 2012
Published online: && &&, 2012
&
8
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Highly Efficient D2 Generation
FULL PAPER
Cheap D2 gas! Convenient generation
of deuterium gas (D2) and preparation
of deuterated compounds on a labora-
tory scale are demonstrated using
a half-sandwich iridium complex with
4,4’-dihydroxy-2,2’-bipyridine (see
scheme). The “umpolung” of a hydro-
gen atom of water was achieved in
consecutive reactions (cationic H+/D+
exchange reaction and anionic hydride
(deuteride) transfer) under mild condi-
tions.
Isotopes
W.-H. Wang, J. F. Hull,
J. T. Muckerman, E. Fujita, T. Hirose,
Y. Himeda* .................... &&&& — &&&&
Highly Efficient D2 Generation by
Dehydrogenation of Formic Acid in
D2O through H+/D+ Exchange on
Iridium Catalyst: Application to the
Synthesis of Deuterated Compounds
by Transfer Deuterogenation
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
9
&
ÞÞ
These are not the final page numbers!