Reduction of CO2 and SO2 with low valent nickel compounds under mild conditions

Article abstract of DOI:10.1039/c1dt10972c

The reaction of [(dippe)Ni(μ-H)]₂ (A) (dippe = 1,2-bis(diisopropyl-phosphinoethane) with CO₂ in toluene afforded the carbonyl nickel(0) compounds of the type {(dippe)Ni(CO)]₂(μ- dippe)}(1) and (dippe)Ni(CO)(dippeO)] (2), which were characterized by standard spectroscopic methods; complex (1) was also characterized by single crystal X-ray diffraction. Reaction of (A) with SO₂ yields the thiosulfate nickel(ii) compound [Ni(dippe)(S₂O₃)] (5), which was fully characterized by standard spectroscopic methods and X-ray crystallography. In both cases, a reduction reaction of CO₂ to CO and SO₂ to S₂O₃^2- with (A) took place under mild conditions.

Full text of DOI:10.1039/c1dt10972c

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
Dalton
Transactions
Cite this: Dalton Trans., 2011, 40, 9116
www.rsc.org/dalton
PAPER
Reduction of CO and SO with low valent nickel compounds under mild
2
2
conditions†
Lucero Gonz a´ lez-Sebasti a´ n, Marcos Flores-Alamo and Juventino J. Garc ´ı a*
Received 24th May 2011, Accepted 28th June 2011
DOI: 10.1039/c1dt10972c
The reaction of [(dippe)Ni(m-H)]
2
(A) (dippe = 1,2-bis(diisopropyl-phosphinoethane) with CO
(m-dippe)}(1) and
dippe)Ni(CO)(dippe O)] (2), which were characterized by standard spectroscopic methods; complex
1) was also characterized by single crystal X-ray diffraction. Reaction of (A) with SO yields the
)] (5), which was fully characterized by standard
spectroscopic methods and X-ray crystallography. In both cases, a reduction reaction of CO to CO and
2
in
toluene afforded the carbonyl nickel(0) compounds of the type {(dippe)Ni(CO)]
2
(
(
2
thiosulfate nickel(II) compound [Ni(dippe)(S
2
O
3
2
2
-
SO
2
to S
2
O
3
with (A) took place under mild conditions.
Introduction
Most of the developed derivatization of CO
insertion of this molecule into organometallic compounds;
nevertheless, another important pathway for the use of CO
its reduction to CO. However, due to the large energy input
2
involves the
18–20
The use of renewable resources is a prerequisite for a sustainable
society. One easily, available and renewable carbon source is
carbon dioxide (CO
abundant, and economical. In recent years, there has been a
significant interest in the catalytic functionalization of CO , due
2
is
2
), which has the advantages of being nontoxic,
required to generate CO from CO
, the former is largely produced
2
1–3
1
in industry from fossil fuels. In addition, even with the use of
strong reducing agents for overcoming the O CO bond enthalpy
2
to the potential of this greenhouse gas as a source of carbon in
the synthesis of both commodity chemicals and complex organic
-1
4,21
of 532 kJ mol , kinetic difficulties are often present.
An
example of a naturally driven process for the CO reduction to
2
4–7
molecules. However, few chemical process utilize CO
2
as a raw
CO is performed by the acetyl-CoA synthase/CO dehydrogenase
8
material. Because CO
2
is the most oxidized state of carbon, the
22
enzymatic system. The reduction of CO
2
to CO has also
complexes
main problem for establishing a chemical processes based on CO
as a starting material regularly faces a high activation energy for
the transformation of CO into useful materials. Therefore, efforts
2
been observed in the thermolysis of some Ni–CO
2
with phosphines as ligands, though there have been very few
15,23
2
documented examples.
to convert CO
2
into useful chemicals will badly need the design
Sulfur dioxide is another small molecule of interest, which has
long been recognized as a polluting by-product from coal, diesel
9
and use of transition metal catalysts.
The formation of transition metal–CO
2
complexes [M–CO ]
2
and natural gas combustion, therefore, the reactions where SO
is
to
2
via direct coordination is a powerful and useful tool to induce
the inert CO molecule to undergo chemical reactions. The
synthesis and chemistry of such [M–CO ] complexes have been of
24–28
involved are of current interest.
The need for converting SO
2
2
less hazardous materials has driven the attention to the study of its
coordination to transition metal fragments and the corresponding
2
10–12
continuous interest during recent years.
of coordination compounds of late transition metals with carbon
dioxide have been characterized crystallographically displaying a
A number of examples
29
reactivity of the formed complexes.
Considering our previous findings on the activation of unreac-
tive bonds using low valent nickel dimeric complexes, we decided
13–15
variety of coordination modes.
The very first structure reported
ligand was for
Also, it is known that
complexes as evidenced by the
number of characterized monomeric and oligomeric compounds
to explore the reactivity of the Ni(I) complex [(dippe)Ni(m-H)]
2
for a complex containing a coordinated CO
2
(
dippe = 1,2-bis(diisopropyl-phosphinoethane) towards CO
2
and
2
14–15
[
Ni(PCy
3
)
2
(h -CO
2
)] by Aresta et al.
SO
2
. We disclose here our findings on such reactivity that yield
Ni(0) and Ni(I) form stable CO
2
nickel-carbonyl and nickel-thiosulfate complexes.
1
6–17
reported so far.
Results and discussions
Reaction of [(dippe)Ni(l-H)]
2
with CO
2
. Synthesis of {[Ni(dippe)-
Facultad de Qu ´ı mica. Universidad Nacional Aut o´ noma de M e´ xico, Mexico
City, 04510, Mexico. E-mail: juvent@servidor.unam.mx
(
CO)]
2
(l-dippe)} (1) and [Ni(dippe)(CO)(dippe O)] (2)
†
Electronic supplementary information (ESI) available. CCDC reference
numbers 827160 and 827161. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c1dt10972c
A
toluene solution of [(dippe)Ni(m-H)] reacted with an
2
excess of carbon dioxide, at room temperature, to yield
9
116 | Dalton Trans., 2011, 40, 9116–9122
This journal is © The Royal Society of Chemistry 2011

View Article Online
Scheme 1 Reaction of CO
2
2
with [(dippe)Ni(m-H)] .
3
1
˚
)] (1.8003(8) A). The Ni–P bond
{
[Ni(dippe)(CO)]
2
(m-dippe)}
(1,
26%),
[Ni(dippe)(CO)-
and for [(CO)
3
Ni(PPh
2
)
2
Ni(CO)
3
(
(
dippe O)] (2, 50%), [Ni(dippe)
4, 9%) see Scheme 1.
2
] (3, 15%) and (dippeO )
2
distances are comparable with the values reported for other tetra-
1
0
hedral d nickel complexes such as [Ni(P(OCH
2
)
3
CCH
3
)
3
NO]BF
4
3
1
1
˚
˚
30,32–33
The P{ H} NMR spectrum for complex (1) shows a doublet
(2.186 A average) and [Ni(CO)(np
3
)] (2.215 A average).
CO stretching frequency for (1) was observed at 1901 cm and is
The
-
1
at 61.1 ppm and a triplet at 39.1 ppm both with JPP = 9.8 Hz, due
to a set of two inequivalent phosphorus. This number of signals
and their multiplicity are in agreement with the X-ray structure
30
indicative of strong p Ni–CO backbonding.
To the best of our knowledge, complex (1) constitutes the
(
Fig. 1); complex 1 displays two nickel centers in a tetrahedral
only structurally characterized example with nickel and P-donor
geometry bridged through the diphosphine (dippe). Each Ni atom
is coordinated to one phosphorus of the bridging diphosphine,
as well as to two phosphorus of the chelating dippe and to
one terminal carbonyl. Considering the observed multiplicity, the
doublet at 61.1 ppm was assigned to the coordinated phosphorus
of the chelating dippe, which is coupled with the phosphorus of the
bridging diphosphine; the latter was assigned to the triplet at 39.1
ppm. Key angles ( ) are: C(22)–Ni(1)–P(2) = 113.19(9), C(22)–
Ni(1)–P(3) = 105.23(9), P(1)–Ni(1)–P(3) = 122.09(3), P(2)–Ni(1)–
P(1) = 91.36(3). The P–Ni–CO angles (109.0(9) average) are shorter
ligands reported from reduction of CO to CO.
2
Pure compound (2) was obtained by purification with a
chromatographic column (see Experimental). Several attempts
to crystallize this complex failed; however, it was characterized
3
1
1
by standard analytical techniques. The P{ H} NMR spectrum
shows a set of three signals, see Fig. 2, a doublet at 60.3 ppm
2
3
( JPP = 10 Hz) assigned to P1, a doublet at 48.2 ppm ( JPP = 23 Hz)
◦
2
assigned to P3 and a double of triplets at 38.5 ppm ( JPP = 10 Hz
3
and JPP = 23 Hz) assigned to P2 which is coupled both to P3 and
P1.
1
3
1
than those reported for the complex [Ni(CO)(np
3
)] (112.70(9)
The C{ H} NMR spectrum for (2) displays a key signal at 206
ppm (JCP = 5.1 Hz) as a quartet assigned to the carbonyl group
due to the coupling to three equivalent phosphorus. All of the
above is consistent with a tetrahedral geometry around the nickel
center. The FT-IR spectrum of (2) is very much similar to the one
30
average) (np
3
= tris(2-diphenylphosphinoethyl)amine) which has
a tetrahedral geometry. The P(2)–Ni(1)–P(1) angle is shorter than
other P–Ni–P angle in the same compound perhaps due to the
bite angle of the chelating dippe. The Ni–CO bond distance of
-
1
˚
obtained for compound (1) showing a strong band at 1901 cm for
the Ni–CO moiety and sharp bands at 1185 and 1157 cm (n
1
(
.759(3) A is close to the Ni–CO bond distance in [Ni(CO)(np )]
3
30
-1
˚
˚
)
1.74 A), but is shorter than those reported for Ni(CO)
4
(1.84 A)
P
O
+
assigned to the mono-coordinated phosphine monoxide. MS-EI
data are consistent for {(Ni(dippe)(CO)(dippe O)} (2): m/z =
86 (3.1%, [M ]–iPr), 570 (0.6%, [M ]–iPr–O), 469 (1.1%, [M ]–
+
+
+
5
(
(
+
iPr)
16%, [M ]–CO–(iPr)
Additionally, a controlled thermolysis of compound (2) in
3
–O–CH
3
), 348 (0.6%, [M ]–(iPr)
2
CH
O).
2
CH
2
(iPr)
2
P
O), 320
+
2
CH CH (iPr)
2
2
2
P
3
1
1
toluene-d
8
under argon was monitored by P{ H} NMR spec-
troscopy and was found to be also rather informative, displaying
signals assigned to compounds (2a), (2b) and (2c), along with the
23
precipitation of metallic nickel, as depicted in Scheme 2. The
1
3
1
C{ H} NMR spectrum for complex (2a) shows a key resonance
at 204 ppm as a triplet (JCP = 4.1 Hz) assigned to the carbonyl
group coupled to two equivalent phosphorus.
When complex (2) was treated with a stream of CO gas,
compounds 2a and 2b were identified by their characteristic
3
1
1
P{ H} NMR signals: a singlet at 70.1 ppm assigned to complex
Fig. 1 ORTEP drawing (50% probability) for complex (1) with H
2
a and two doublets at 47.3 and 6.1 ppm with JPP = 37 Hz assigned
◦
atoms omitted for clarity. Selected distances ( A˚ ) and angles ( ):
Ni(1)–C(22) = 1.759(3), Ni(1)–P(2) = 2.1909(8), Ni(1)–P(1) = 2.2057(8),
Ni(1)–P(3) = 2.2231(8), O(1)–C(22) = 1.155(3), C(22)–Ni(1)–P(1) =
to compound 2b. Likewise, compounds (3) and (4) were also
3
1
1
identified and characterized by their distinctive signals on P{ H}
NMR, singlets at 50.7 and 48.8 ppm respectively, and by their
1
08.67(9), P(2)–Ni(1)–P(1) = 91.36(3), P(2)–Ni(1)–P(3) = 116.10(3).
This journal is © The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 9116–9122 | 9117

View Article Online
31
1
Fig. 2
P{ H} spectrum of [Ni(dippe)(CO)(dippe O)] (2).
Scheme 2 The thermolysis of (2).
comparison with authentic samples prepared independently (see
Reaction of [(dippe)Ni(l-H)]
[Ni(dippe)(S )]
2
with SO . Synthesis of
2
Experimental).
Few stable Ni–h -CO
been reported.
experiments, complexes of the type [(dippe)Ni–h -CO
2
O
3
2
2
complexes with P-donor ligands have
14,23
A toluene solution of (A) with a sulfur dioxide stream reacted
immediately giving a change in color from wine red to red-brown
over a one hour period to yield complex [Ni(dippe)(S
Under the conditions used in the current
2
2
] have not
2
O
3
)] (5) and
been observed, but such complex can be envisaged as the precursor
dippeO (4). Complex (5) was obtained as yellow air-stable crystals
2
for compounds (1) and (2). In order to trap the corresponding
3
1
1
2
in 70% isolated yield. The P{ H} NMR spectrum of the crude
Ni–h -CO
2
intermediate, a toluene solution of [(dtbpe)Ni(m-H)]
2
reaction mixture displays two doublets at 91.5 and 85.5 ppm, with
(
dtbpe = 1,2-bis-tert-butylphosphino)ethane) was treated with a
2
2
JPP = 41.1 Hz, assigned to the [Ni(dippe)(S O )] complex, along
stream of CO
2
to yield [(dtbpe)Ni(h -CO
2
)] as a yellow powder.
2
3
3
1
1
with a sharp singlet for dippeO at 48 ppm and a broad singlet at
70.3 ppm.
Suitable crystals for X-ray diffraction studies were obtained
for (5) from a concentrated toluene solution at 65 C. The
corresponding ORTEP diagram is shown in Fig. 3 (also see
Table 1). The nickel atom is considered to be in a slightly
distorted square planar geometry coordinated (t = 0.052) to
the chelating dippe and to the oxygen and sulfur atoms of the
This complex was identified by direct comparison of the P{ H}
2
23
NMR data recently reported by Hillhouse et al. These results
confirm that, under similar conditions, the stabilities of the Ni–
◦
2
h -CO
2
complexes are related to the steric properties of the
14
phosphines.
Despite the fact that on using dippe as ancillary ligand, the Ni–
2
h -CO
2
complex was not observed, the idea that CO
2
reduction
] adduct
2
to CO occurred via the corresponding [(dippe)Ni–h -CO
2
˚
chelating thiosulfate. Ni–P bond distances (2.14(8) A average) are
seems to be quite reasonable.
comparable with the values reported for related square-planar
There are very few papers in which the metal-promoted
reduction of carbon dioxide occurs under mild conditions (room
36
nickel (III) complexes. The distances and angles of the thiosulfate
ion in (5) are comparable with the interatomic distances and angles
in closely related structures containing the chelating S,O counter
15
temperature and atmospheric pressure). Reduction of CO to
2
CO at a nickel center has been observed by the thermolysis of
37
◦
ion.
Key FT-IR frequencies for complex (5) (v(SO) = 1464, 1257,
complexes of the type [L
n
Ni–h-CO
2
] [L = PCy
3
, dtbpe] at 80 C to
23,34
yield L
n
Ni(CO)
2
.
In both cases, the ancillary phosphine ligands
-
1 24
1
146 and 556 cm ) are in agreement with the ones reported for
acted as the oxygen sink. Probably, the phosphine monoxide is
38
15,35
other Ni-thiosulfate complexes.
There are several reports for the addition of SO
formed first, as evidenced here in complex (2).
In summary,
2
to monohydride
since the thermolysis of (2) yielded similar products to the
2
11
complexes or displacement of H from dihydride complexes
thermolysis of the [(dtbpe)Ni–h -CO
2
] adduct, we propose that
2
3
9–41
by SO
2
.
To note, there are only a few reports on the
by hydride complexes of transition metals to
compound (2) could be an intermediate in the formation of
reduction of SO
2
dicarbonyl compounds of the type [(diphosphine)-Ni-(CO) ].
2
9
118 | Dalton Trans., 2011, 40, 9116–9122
This journal is © The Royal Society of Chemistry 2011

View Article Online
Table 1 Crystallographic data for (1) and (5)
Compound
(1)
(5)
Empirical formula
Formula weight
Temperature (K)
Crystal system
C
44
H
96Ni
2
O
2
P
6
14 3 2 2
C H32NiO P S
960.45
130(2)
Triclinic
P-1
433.17
130(2)
Tetragonal
P42/n
22.708(3)
22.708(3)
7.902(2)
90
Space group
a ( A˚ )
8.7220(6)
b ( A˚ )
11.5158(8)
14.3744(10)
102.320(6)
91.092(6)
112.112(7)
1298.88(16)
1
1.228
522
0.28 ¥ 0.18 ¥ 0.049
4.27 to 68.11
c ( A˚ )
◦
a ( )
◦
b ( )
90
90
◦
g ( )
V ( A˚ )
Z value
(calcd) (mg m )
F(000)
Crystal size (mm )
q range ( )
No. of rflns collected
3
4075.24(13)
8
1.412
1840
0.266 ¥ 0.0823 ¥ 0.0443
3.59 to 26.05
29432
-3
D
3
◦
8546
No. of indep rflns (Rint) (%)
Completeness to theta (%)
Refinement method
4721 [2.98]
99.3
Full-matrix least-squares on F
4721/0/256
1.083
4020 [4.94]
99.8
Full-matrix least-squares on F
4020/0/207
1.096
2
2
No. data/restraints/parameters
2
Goodness-of-fit on F
Final R indices [I > 2s(I)] (%)
R = 3.94, R
w
= 9.05
= 9.57
R = 3.61, R
w
= 9.61
= 9.89
R indices (all data) (%)
R = 4.99, R
w
R = 4.88, R
w
Largest diff. peak and hole (e A˚ -
3
)
0.472 and -0.357
0.887 and -0.905
has been observed for compounds of the type Cp
Mo, W) where SO
complex Cp M(S O ) and water. An independent preparation of
2
MH
2
(M =
2
reacted to yield the corresponding thiosulfate
24
2
2
3
this complex was made and the product exhibited all the above
quoted spectroscopic details (see Experimental). To the best of
our knowledge, the current reduction of SO to thiosulfate using
2
nickel is the first one reported. A mechanistic proposal for this
transformation is depicted in Scheme 3.
Fig.
H
3
ORTEP drawing (50% probability) for complex (5) with
atoms omitted for clarity. Selected distances ( A˚ ) and angles
◦
(
): Ni(1)–O(1) = 1.9172(18), Ni(1)–P(2) = 2.1332(8), Ni(1)–P(1) =
.1570(7), Ni(1)–S(2) = 2.1812(9), Ni(1)–S(1) = 2.6660(7), O(1)–S(1) =
.513(2), O(2)–S(1) = 1.429(3), O(3)–S(1) = 1.429(2), S(1)–S(2) =
.0125(11), O(1)–Ni(1)–P(2) = 172.00(7), O(1)–Ni(1)–P(1) = 94.49(6),
2
1
2
P(2)–Ni(1)–P(1) = 88.98(3), O(1)–Ni(1)–S(2) = 81.57(6), P(2)–Ni(1)–S(2) =
9
6.29(3), P(1)–Ni(1)–S(2)
P(2)–Ni(1)–S(1) 143.18(3),
S(2)–Ni(1)–S(1) = 47.78(3), S(1)–O(1)–Ni(1) = 101.36(10).
=
168.88(4), O(1)–Ni(1)–S(1)
=
33.81(6),
127.83(3),
=
P(1)–Ni(1)–S(1)
=
Scheme 3
metal–thiosulfate complexes. The broad signal at 70.3 ppm turned
out to be a rather unstable intermediate and was not isolated
or characterized. However, we speculate that it may be related
The above proposal invokes the initial formation of a Ni–SO
adduct, the SO moiety is proposed to be reduced by the reaction
with H to yield H O and to the participation of the phosphine
ligand to yield dippeO , the resulting “(dippe)NiS” reacts further
2
to a Ni–SO
reported.
2
9,41
adduct, since metal–SO
Consequently, it would not be unreasonable to
2
adducts have been widely
2
3
2
2
suggest the possibility of the formation of intermediate complexes
2
2
1
of the type Ni–k -SO
2
or Ni–k -SO
2
. A closely related reactivity
with SO
3
to produce the corresponding thiosulfate complex.
This journal is © The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 9116–9122 | 9119

View Article Online
3
1
1
Conclusions
powder that was further dried under vacuum for 6 h. The P{ H}
NMR spectrum, in toluene-d , of this sample displays several
resonances assigned to four different compounds (vide infra). The
sample was warmed at 65 C in a silicon oil bath for 5 days and it
was monitored by P{ H} NMR spectroscopy. One product was
crystallized off after 2 days of heating as colorless crystals and was
separated simply by decantation. The colorless triangular plates
were found to be suitable for X-ray diffraction studies, identified as
8
In conclusion, the Ni(I) complex [(dippe)Ni(m-H)] (dippe =
2
1
,2-bis(diisopropyl-phosphinoethane) allowed the reduction of
◦
2
-
CO
2
to CO and SO
2
to S
2
O
3
under mild conditions to yield
31
1
novel mono- and bi-metallic nickel(0) complexes of the type
[(dippe)Ni(CO)]
(m-dippe)}, (dippe)Ni(CO)(dippe O)] and the
nickel(II) complex [Ni(dippe)(S )]. The reduction reactions
possibly occurred via intermediates of Ni–(CO ) and Ni–(SO
)]. This agrees with the
{
2
2
O
3
2
2
)
{
[(dippe)Ni(CO)]
2
(m-dippe)} (1). Crystals of the latter compound
2
adducts as evidenced for [(dtbpe)Ni(h -CO
2
were found to be slightly soluble in different solvents such as
toluene, THF, benzene, acetone and ethanol. Yield: 26%. Anal.
assumption that the nature of the metal–ancillary ligand fragment
is of critical importance in determining the coordination mode
and the reactivity for CO
underway to apply the observed species in synthetic methods for
the production of valuable organic derivatives.
Calcd. for (1), C44
C, 54.98; H, 10.03; O, 3.32. P{ H} NMR (22 C, 300 MHz,
): d 61.1 (d, P(iPr) CH CH P(iPr) , JPP = 9.8 Hz), 39.1(t,
, JPP = 9.8 Hz); H NMR (22 C, 300 MHz, C
.2–1.9 (m, CH, 12H), 1.8–1.1 (m, CH , CH , 84H). The FT-IR
H
96Ni
2
O
2
P
6
: C, 55.02; H, 10.07; O, 3.33. Found:
31
1
◦
2
and SO
2
activation. Current studies are
C
7
D
8
2
2
2
2
◦
1
(
m-P(iPr)
2
7
8
D ): d
2
2
3
spectrum was recorded in solution (toluene); a key band located
Experimental
-
1
at 1902 cm was assigned to n
Further heating of the reaction mixture for 5 days at 65
showed resonances due to the four former products on P{ H}
NMR spectroscopy. Then, the solvent was removed from the
mixture obtaining a brown residue and 5 mL of dry ethanol
were added giving a colorless solid. The solid was filtered, washed
C
O
.
◦
Unless otherwise noted, all the operations were carried out
in a MBraun glovebox (<1 ppm H
C
3
1
1
2
O and O
2
) or by using
high-vacuum and standard Schlenk techniques under an argon
atmosphere. Toluene was dried and distilled over sodium. Hexane
and THF were dried and distilled from dark-purple solutions
of sodium/ketyl benzophenone. Ethanol was dried and distilled
from solutions of magnesium/iodine. Deuterated solvents for
NMR experiments were purchased from Cambridge Isotope
Laboratories and stored over 3 A molecular sieves in a glovebox.
Celite and silica gel were dried by heating at 200 C under vacuum
for 20 h and stored in a glovebox. Complex [(dippe)Ni(m-H)]
3
1
1
with ethanol and dried under vacuum for 6 h. P{ H} NMR
spectrum of this sample showed to be the same for compound
(1). The mother liquors were evaporated to dryness and the
3
1
1
˚
residue was analyzed by P{ H}NMR spectroscopy, showing
signals for compounds 2, 3 and 4. The remaining mixture was
separated by column chromatography using silica-gel, eluting
with hexane/ethanol 95 : 5 and increasing polarity to ethanol.
Complex 3 was recovered as a light-brown solution in the first
fraction, complex 2 was recovered as a yellow solution in the
second fraction eluting with 95 : 5 hexane/ethanol and 4 was
recovered as a dark-brown solution, eluting with pure ethanol.
Solvent was removed from all fractions and the corresponding
residues were vacuum-dried for 6 h. Compounds 2, 3 and 4
where characterized by standard spectroscopic methods. Yield for
complex (2): 50%. Anal. Calcd. for [(dippe)Ni(CO)(dippe O)]
◦
42
2
43
(
A) and [(dippe)NiCl
procedure. The bisphosphine ligand, dippe, was synthesized from
,2-bis(dichlorophosphino)ethane (Aldrich) and an isopropyl-
2
] were prepared according to the literature
1
44
magnesium chloride solution in THF (2.0 M, Aldrich). All other
chemicals and filters aids were reagent grade and were used as
received. The purification of the new compounds was made by
crystallization or by column chromatography. FT-IR spectra were
1
13
1
determined using a Perkin Elmer 1600 series FTIR. H, C{ H}
and P{ H} NMR spectra were recorded at room temperature
on a 300 MHz Varian Unity spectrometer in toluene-d , benzene-
3
1
1
(2), C29
H
65NiO
2
P : C, 55.43; H, 10.43; O, 5.09. Found: C, 55.39;
4
8
1
13
1
31
1
◦
d
6
or CDCl
3
, unless otherwise stated, and all H and C{ H}
H, 10.42; O, 5.01. P{ H} NMR (22 C, 300 MHz, C
(d, P(iPr) CH CH P(iPr) , JPP = 10.5 Hz), 47.8 (d, ((iPr)
PP = 23.4 Hz), 38.5 (m, (P(iPr)
7
D
8
): d 60.3
O,
, JPP = 23.4, 10.5 Hz). H NMR
): d 2.1 - 1.7 (m, CH, 8H), 1.32–0.864
chemical shifts (d, ppm) are reported relative to the residual proton
2
2
2
2
)
2
2
P
3
1
1
1
resonance in the deuterated solvents. P{ H} NMR spectra were
J
2
◦
referred to an external 85% H PO solution. All air sensitive
3
4
(22 C, 300 MHz, C
6
D
6
3
1
1
◦
samples in this work were handled under inert atmosphere using
thin wall (0.38 mm) WILMAD NMR tubes equipped with J.
Young valves. Mass spectrometry (MS-EI ) of pure compounds
was performed by USAI-UNAM using a Thermo-Electron DFS.
X-Ray diffraction measurements were performed on an Oxford
Diffraction Gemini-Atlas diffractometer.
(m, CH
d 206.4 (q, CO, JCP = 5.5 Hz), 27.94 (m, (CH
4.1 Hz), 27.7–27.3 (m, (CH –CH ), 23.7 (m, (CH(CH
15.1, 5.2 Hz), 23.4 (m, (CH(CH )), 20.5 (m, (CH(CH
)), 19.9 (m, CH(CH )), 19.5 (m, (CH(CH
2
, CH
3
, 56H). C{ H} NMR (22 C, 300 MHz, C
–CH ), JCP = 9.6,
), JCP =
6
D ):
6
2
2
+
2
2
3
)
2
3
)
2
3
)
2
), 20.2
)),
), JCP = 15.1, 1.8 Hz). MS-EI for (2): m/z =
(m, (CH(CH
16.6 (dd, (CH
3
)
2
3
)
2
3 2
)
+
2
+
–CH
2
+
+
5
86 (3.1%, [M ]–(iPr), 570 (0.6%, [M ]–iPr)–O), 469 (1.1%, [M ]–
+
(
(
iPr)
3
–O–CH
3
), 348 (0.6%, [M ]–(i-Pr)
2
CH
2
CH
2
(iPr)
2
P O), 320
Reaction of [(dippe)Ni(l-H)]
[(dippe)Ni(CO)]
(l-dippe)} (1), [(dippe)Ni(CO)(dippe O)] (2),
Ni(dippe) ] (3), (dippeO ) (4)
2
(A) with CO
2
. Synthesis of
+
+
16%, [M ]–CO–(iPr)
CH CH P(iPr) NiCO). FT-IR (toluene): 1902 cm (n
Signals at 1185 and 1157 cm were assigned to the phosphine
2
CH
2
CH
2
iPr)
2
P O), 278 (12%, [M ]–
{
2
-
1
P(iPr)
2
2
2
2
C
O
).
[
2
2
-
1
35
A 25 mL Schlenk flask was loaded with 4 mL of a toluene solution
of (A) (100 mg, 0.16 mmol). The solution was stirred and a CO
stream was bubbled at room temperature for 1 h. During this
time, the color of the solution gradually changed from wine-red to
brown. After this time, the solvent was removed to yield a brown
oxide moiety.
For [Ni(dippe) ] (3):
d 50.7 (s, P(iPr) CH CH P(iPr) ), H NMR (22 C, 300 MHz,
45
31
1
◦
2
2
P{ H} NMR (22 C, 300 MHz, C D ):
1
◦
2
7
8
2
2
2
C D ): d 2.1–2.18 (m, CH, 8H), 1.91–2.1 (m, CH , 8H), 1.12–1.24
7
8
2
(m, CH , 48H).
3
9
120 | Dalton Trans., 2011, 40, 9116–9122
This journal is © The Royal Society of Chemistry 2011

View Article Online
3
1
1
◦
For (dippeO
d 48.8 (s, O P(iPr
MHz, C ): d 1.62–1.5 (m, CH, 4H), 1.4–1.22 (m, CH
.05–0.85 (m, CH
m/z = 294 (4.8%, [M ]), 278 (1.5%, [M ]–O), 251 (100%, [M ]–
2
) (4): P{ H} NMR (22 C, 300 MHz, C
)CH CH (iPr) O). H NMR (22 C, 300
, 4 H),
, 24H). Mass spectrometry (MS-EI ) for (4):
7
D
8
):
Independent synthesis of [(dippe)Ni(S
and Na
2
O
3
)] (5) with [(dippe)NiCl ]
2
1
◦
2
2
2
2
P
2
S
2
O
3
7
D
8
2
+
Complex (5) also was prepared independently by reacting
[(dippe)NiCl ] and NaS . A 25 mL Schlenk flask was charged
with [(dippe)NiCl ] (150 mg, 0.38 mmol), Na (150 mg, 0.38
1
3
+
+
+
2
2
O
3
+
+
2
2
S
2
O
3
(
iPr)), 235 (30%, [M ]–(iPr)–O), 219 (12%, [M ]–(iPr)–O ).
2
mmol) and distilled water (10 mL). The reaction mixture was
stirred and heated under reflux for 12 h. After this time, an orange-
brown solution was obtained. Complex (5) was extracted with
ethyl acetate and then crystallized from a concentrated solution
Thermolysis of (2)
A pure sample of (2) was dissolved in 0.7 mL of toluene-d
transferred into a J. Young NMR tube and sealed under argon.
The sample was heated at 80 C for 2 days. According to the
8
,
◦
cooled at 5 C. Yellow crystals were filtered, washed with hexane
◦
and dried under vacuum. Yield: 85%. Pure crystals were analyzed
1
13
1
31
1
3
1
1
by NMR H, C{ H} and P{ H} to confirm all the data above
quoted (vide supra).
P{ H} NMR spectra the sample did not show decomposition
◦
products during this time. Further heating to 100 C for one hour
3
1
1
showed new resonances for three new compounds in the P{ H}
NMR spectrum, along with the formation of metallic nickel. Full
◦
thermolysis of (2) was achieved at 100 C for 5 hours to yield
X-ray structure determination
[
(dippe)Ni(CO) ] (2a), dippeO (2b) and dippe (2c), according to
2
3
1
1
31
1
The colorless triangular plates (1) and pale-yellow needle (5)
crystals, suitable for X-ray diffraction studies, were obtained from
a concentrated solution in toluene-d .
8
The crystals of compounds (1) and (5) were mounted under
LVAC FOMBLIN Y on glass fibers and immediately placed
under a cold nitrogen stream at 130 K on a Oxford Diffraction
their corresponding P{ H} NMR signals. For 2a: P{ H} NMR
◦
(
22 C, 300 MHz, C
7
D
8
): d 70.1 (s, (iPr
2
)
2
PCH
2
CH
2
P(iPr
2
)
2
).
=
),
1
3
1
◦
C{ H} NMR (22 C, 300 MHz, C
.1 Hz), 25.8 (t, (CH(CH ), JCP = 9.8 Hz), 23.8 (dd, (CH(CH
CP = 8.6, 6.9 Hz), 19.6 (m, (CH
7
8
D ): d 204.3 (t, CO, JCP
4
3
)
2
3
)
2
3
1
1
J
2
CH
2
). For 2b: P{ H} NMR (22
◦
C, 300 MHz, C
7
D
8
): d 47.3 (d, (iPr
2 2
)
P
O, JPP = 37 Hz), 6.1 (d,
1
3
1
◦
Gemini “A” diffractometer with a CCD area detector, with
˚
P(iPr
2
)
2
, JPP = 37 Hz). C{ H} NMR (22 C, 300 MHz, C
7
D
8
):
=
),
a radiation source of lCu Ka = 1.5418 A for (1) and lMo Ka
=
d 23.8 (d, (CH(CH
3
)
2
), JCP = 14.8 Hz), 23 (d, (CH(CH
.5 Hz), 22.8 (d, (CH(CH ), JCP = 4.1 Hz),), 20.2 (d, (CH(CH
CP = 16 Hz), 16 (dd, (CH CH
CH
), JCP = 20.8, 5.0 Hz). For 2c: P{ H} NMR (22 C, 300
MHz, C ): d 5.5 (s, P(iPr CH CH P(iPr) ).
3
)
2
), JCP
˚
.71073 A for (5) using graphite-monochromatized radiation.
0
9
J
(
3
)
2
3 2
)
46
CrysAlisPro and CrysAlis RED software packages were used
for data collection and data integration. Data sets consisted of
frames of intensity data collected with a frame width of 1 in w,
2
2
), JCP = 17.9, 2.7 Hz), 14 (dd,
31 1
◦
CH
2
2
◦
7
D
8
2
)
2
2
2
2
-
1
a counting time of 1.7 to 6.8 s frame , and a crystal-to-detector
distance of 55.00 mm. The double pass method of scanning was
used to exclude any noise. The collected frames were integrated
by using an orientation matrix determined from the narrow
frame scans. Final cell constants were determined by a global
refinement; collected data were corrected for absorbance by using
Reaction of [(dippe)Ni(l-H)]
(dippe)Ni(S )] (5)
2
(A) with SO . Synthesis of
2
[
2
O
3
Complex (A) 100 mg, 0.16 mmol was dissolved in dry toluene
5 mL), cooled in a dry ice–acetone bath and bubbled with a stream
(
47
Analytical numeric absorption correction using a multifaceted
crystal model based on expressions upon the Laue symmetry using
equivalent reflections.
of SO
2
. After 5 min, an orange-brown solution was observed.
◦
The solution was constantly stirred for 15 min at -78 C and
then was gradually warmed to room temperature. During this
time, the color of the solution changed from orange-brown to red-
Structure solution and refinement were carried out with the
48
program(s): SHELXS97 and SHELXL97; for molecular graph-
brown under an SO
the solvent was removed to yield a red-brown powder that was
dried for 6 h under vacuum. Yield for complex [Ni(dippe)(S )]
5): 70%. Anal. Calcd. for pure (5), C13 : C, 37.25;
H, 7.21; O, 11.45. Found: C, 37.21; H, 7.18; O, 11.29. For pure
2
atmosphere. After 1 h at room temperature,
49
ics: ORTEP-3 for Windows; and the software used to prepare
50
material for publication: WinGX
Full-matrix least-squares refinement was carried out by min-
2
O
3
(
H
30NiO
3
P
2
S
2
2
2 2
imizing (F
o
- F ) . All non-hydrogen atoms were refined
c
3
1
1
◦
anisotropically. H atoms attached to C atoms were placed in
geometrically idealized positions and refined as riding on their
(
J
5): P{ H} NMR (22 C, 300 MHz, C
7
D
8
): d 91.5 (d, P(iPr) ,
2
1
◦
PP = 41.1 Hz), 85.5 (d, P(iPr) , JPP = 41.1 Hz). H NMR (22 C,
2
˚
parent atoms, with C–H = 0.96–1.00 A and Uiso(H) = 1.2Ueq(C),
3
CH
CH(CH
2
J
(
00 MHz, CDCl
3
): d 2.35–1.77 (m, CH, CH
2
, 8H), 1.5–1.28 (m,
): d 26.8 (d,
, JPP = 21.6 Hz),
), JCP = 29.4, 13.9 Hz), 19.0 (dd, CH CH
CP = 64, 1.9 Hz), 19.0 (d, CH CH , JCP = 48, 1.1 Hz), 18.9 (dd,
), JCP = 28.1, 9. Hz). FT-IR spectrum was recorded as
a KBr pellet and showed bands at 1464, 1412, 1387, 1367, 1257,
1
3
1
◦
or 1.5 Ueq (C) for methylene, methyne and methyl groups. Crystal
data and experimental details of the structure determination are
listed in the ESI†.
3
, 24H). C{ H} NMR (22 C, 300 MHz, CDCl
3
3
)
2
), JCP = 26.9 Hz), 25.1 (d, CH(CH
)
3 2
2.9 (dd, (CH(CH
3
)
2
2
2
,
2
2
CH(CH
)
3 2
Acknowledgements
-
1
1
139, 1030, 908, 883, 656 cm . Suitable crystals of this complex for
X-ray diffraction studies were obtained (vide infra). A resonance
at 48.8 ppm in a crude mixture was identified as the phosphine
dioxide. An unknown intermediate displays a broad signal at 70.3
ppm.
We thank PAPIIT-DGAPA-UNAM (IN-201010) and CONA-
CYT (080606) for their financial support. L G-S also thanks
CONACYT for a PhD grant and also we thank Dr. A. Ar e´ valo
for technical assistance.
This journal is © The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 9116–9122 | 9121

View Article Online
References
24 G. J. Kubas and R. R. Ryan, Inorg. Chem., 1984, 23, 3181–3183.
5 G. J. Kubas, H. J. Wasserman and R. R. Ryan, Organometallics, 1985,
4, 2012–2021.
2
1
H. Arakawa, M. Aresta, J. N. Armor, M. A. Barteau, E. J. Beckman,
A. T. Bell, J. E. Bercaw, C. Creutz, E. Dinjus, D. A. Dixon, K. Domen,
D. L. DuBois, J. Eckert, E. Fujita, D. H. Gibson, W. A. Goddard, D.
W. Goodman, J. Keller, G. J. Kubas, H. H. Kung, J. E. Lyons, L. E.
Manzer, T. J. Marks, K. Morokuma, K. M. Nicholas, R. Periana, L.
Que, J. Rostrup-Nielson, W. M. H. Sachtler, L. D. Schmidt, A. Sen, G.
A. Somorjai, P. C. Stair, B. R. Stults and W. Tumas, Chem. Rev., 2001,
26 K. A. Kubat-Martin, G. J. Kubas and R. R. Ryan, Organometallics,
1989, 8, 1910–1915.
27 G. J. Kubas and R. R. Ryan, J. Am. Chem. Soc., 1985, 107, 6138–
6140.
28 G. J. Kubas, H. J. Wasserman and R. R. Ryan, Organometallics, 1985,
4, 419–421.
29 W. A. Schenk, Dalton Trans., 2011, 40, 1209–1219.
30 C. A. Ghilardi, A. Sabatini and L. Sacconi, Inorg. Chem., 1976, 15,
2763–2767.
1
01, 953–996.
2
3
4
5
6
7
D. H. Gibson, Chem. Rev., 1996, 96, 2063–2096.
D. H. Gibson, Coord. Chem. Rev., 1999, 185–186, 335–355.
W. Leitner, Coord. Chem. Rev., 1996, 153, 257–284.
31 R. H. B. Mais, P. G. Owston, D. T. Thompson and A. M. Wood, J.
D. J. Darensbourg, Inorg. Chem., 2010, 49, 10765–10780.
D. J. Darensbourg, Chem. Rev., 2007, 107, 2388–2410.
A. Correa and R. N. Mart ´ı n, J. Am. Chem. Soc., 2009, 131, 15974–
Chem. Soc. A, 1967, 1774–1776.
32 D. Berglund and D. W. Meek, Inorg. Chem., 1972, 11, 1493–1496.
33 J. H. Meiners, C. J. Rix, J. C. Clardy and J. G. Verkade, Inorg. Chem.,
1975, 14, 705–710.
1
5975.
8
9
A. Behr, Carbon Dioxide Activation by Metal Complexes, VCH,
34 M. Aresta and A. Dibenedetto, Catal. Today, 2004, 98, 455–462.
35 C. Bianchini, C. Mealli, A. Meli and M. Sabat, Inorg. Chem., 1984, 23,
2731–2732.
Weinheim, 1988.
T. Sakakura, J.-C. Choi and H. Yasuda, Chem. Rev., 2007, 107, 2365–
2
387.
36 S. S. Oster, R. J. Lachicotte and W. D. Jones, Inorg. Chim. Acta, 2002,
1
1
0 D. A. Palmer and R. Van Eldik, Chem. Rev., 1983, 83, 651–731.
330, 118–127.
1 P. A. Vigato, S. Tamburini and D. E. Fenton, Coord. Chem. Rev., 1990,
37 E. Freire, S. Baggio, J. C. Mu n˜ oz and R. Baggio, Acta Cryst., 2002,
C58, m455–m458.
1
06, 25–170.
1
1
2 K. K. Pandey, Coord. Chem. Rev., 1995, 140, 37–114.
38 M. L. H. Green, A. H. Lynch and M. G. Swanwick, J. Chem. Soc.,
Dalton Trans., 1972, 1445.
39 M. S. Morton, R. J. Lachicotte, D. A. Vicic and W. D. Jones,
Organometallics, 1999, 18, 227–234.
40 C. G. Kim and D. Coucouvanis, Inorg. Chem., 1993, 32, 1881–1882.
41 A. Shaver and P. Y. Plouffe, Inorg. Chem., 1992, 31, 1823–1826.
42 D. A. Vicic and W. D. Jones, J. Am. Chem. Soc., 1997, 119, 10855–
10856.
3 C. H. Lee, D. S. Laitar, P. Mueller and J. P. Sadighi, J. Am. Chem. Soc.,
2
007, 129, 13802–13803.
1
1
1
1
1
1
2
4 M. N. Aresta, C. F. Nobile, V. G. Albano, E. Forni and M. Manasero,
J. Chem. Soc., Chem. Commun., 1975, 636–637.
5 M. N. Aresta and C. F. Nobile, J. Chem. Soc., Dalton Trans., 1977,
7
08–711.
6 P. W. Jolly, S. Stobbe, G. Wilke, R. Goddard, C. Kr u¨ ger, J. C. Sekutowski
and Y.-H. Tsay, Angew. Chem., 1978, 90, 144–145.
43 F. Scott, C. Kr u¨ ger and P. Betz, J. Organomet. Chem., 1990, 387, 113–
7 P. W. Jolly, K. Jonas, C. Kr u¨ ger and Y.-H. Tsay, J. Organomet. Chem.,
121.
1
971, 33, 109–122.
44 F. G. N. Cloke, V. C. Gibson, M. L. H. Green, V. S. B. Mtetwa and K.
Prout, J. Chem. Soc., Dalton Trans., 1988, 2227–2229.
45 D. A Vicic and W. D. Jones, J. Am. Chem. Soc., 1999, 121, 7606.
46 Oxford Diffraction CrysAlis CCD and CrysAlis RED, Oxford Diffrac-
tion Ltd, Abingdon. England, 2010.
8 H. Mizuno, J. Takaya and N. Iwasawa, J. Am. Chem. Soc., 2010, 133,
1
251–1253.
9 A. Gra e˙ t, L. Sinault, M. B. Fusaro, A.-L. Vallet, C. Seu, J. L. Kilgore
and M. M. Baum, Organometallics, 2010, 29, 1997–2000.
0 J. Wu, J. C. Green, N. Hazari, D. P. Hruszkewycz, C. D. Incarvito and
T. J. Schmeier, Organometallics, 2010, 29, 6369–6376.
47 R. C. Clark and J. S. Ried, Acta Crystallogr., Sect. A: Found.
Crystallogr., 1995, 51, 887.
2
2
2
1 X. Yin and J. R. Moss, Coord. Chem. Rev., 1999, 181, 27–59.
2 S. W. Ragsdale, Crit. Rev. Biochem. Mol. Biol., 2004, 39, 165–195.
3 J. S. Anderson, V. M. Iluc and G. L. Hillhouse, Inorg. Chem., 2010, 49,
48 G. M. Sheldrick, SHELXS97 and SHELXL97, University of Gottin-
gen, Germany, 2008.
49 L. J. Farrugia, J. Appl. Crystallogr., 1997, 30, 565.
50 L. J. Farrugia, J. Appl. Crystallogr., 1999, 32, 837.
1
0203–10207.
9
122 | Dalton Trans., 2011, 40, 9116–9122
This journal is © The Royal Society of Chemistry 2011