Carbonyl abstraction reactions of Cp*Mo(PMe3)3H with CO2, (CH2O)n, HCO2H, and MeOH: the synthesis of Cp*Mo(PMe3)2(CO)H and the catalytic decarboxylation of formic acid

Article abstract of DOI:10.1016/S0022-328X(01)01218-9

Cp*Mo(PMe₃)₃H undergoes carbonyl abstraction reactions with a variety of reagents, including CO₂, (CH₂O)_n, HCO₂H, and MeOH to yield Cp*Mo(PMe₃)₂(CO)H. The reaction bet

Full text of DOI:10.1016/S0022-328X(01)01218-9

Journal of Organometallic Chemistry 642 (2002) 9–15
www.elsevier.com/locate/jorganchem
Carbonyl abstraction reactions of Cp*Mo(PMe3)3H with CO2,
(CH2O)n, HCO2H, and MeOH: the synthesis of
Cp*Mo(PMe3)2(CO)H and the catalytic decarboxylation of formic
acid
Jun Ho Shin, David G. Churchill, Gerard Parkin *
Department of Chemistry, Columbia Uni6ersity, Ha6emeyer Hall, Box 866, mail code 3115, New York, NY 10027, USA
Received 27 March 2001; received in revised form 2 August 2001; accepted 15 August 2001
Abstract
Cp*Mo(PMe3)3H undergoes carbonyl abstraction reactions with a variety of reagents, including CO2, (CH2O)n, HCO2H, and
MeOH to yield Cp*Mo(PMe3)2(CO)H. The reaction between Cp*Mo(PMe3)3H and HCO2H has been studied by 1H-NMR
spectroscopy, which indicates that the initial interaction involves protonation of the molybdenum center to give
[Cp*Mo(PMe3)3H2][HCO2]; upon heating to 80 °C, however, [Cp*Mo(PMe3)3H2][HCO2] is converted to the carbonyl complex
Cp*Mo(PMe3)2(CO)H. In the presence of excess HCO2H, Cp*Mo(PMe3)2(CO)H reacts further to yield Cp*Mo(PMe3)2(CO)(h1-
O2CH); the latter complex undergoes decarboxylation at 80 °C and regenerates Cp*Mo(PMe3)2(CO)H. Thus,
Cp*Mo(PMe3)2(CO)H serves as a catalyst for the decomposition of HCO2H to CO2 and H2. Although the formate complex
Cp*Mo(PMe3)2(CO)(h1-O2CH) has not been isolated, the molecular structure of the acetate derivative Cp*Mo(PMe3)2(CO)(h1-
O2CMe) has been determined by X-ray diffraction. © 2002 Published by Elsevier Science B.V.
Keywords: Synthesis; Carbonyl abstraction; Catalytic decarboxylation
1. Introduction
2. Results and discussion
We have previously reported the pentamethylcy-
clopentadienyl molybdenum trimethylphosphine com-
plexes Cp*Mo(PMe3)H5, Cp*Mo(PMe3)2H3, and
Cp*Mo(PMe3)3H, together with their use to prepare
dinuclear complexes that contain sulfur bridges, e.g.
[Cp*Mo(m-SMe)2]2 and [Cp*Mo(m-S)(m-SH)]2 [1]. In
this paper, we describe further studies on
Cp*Mo(PMe3)3H that highlight its ability to abstract
Cp*Mo(PMe3)3H reacts readily with CO at 80 °C to
yield the carbonyl complex Cp*Mo(PMe3)2(CO)H
(Scheme
1).
The
clean
synthesis
of
Cp*Mo(PMe3)2(CO)H is notable in the sense that
Cp*Mo(PMe3)2(CO)H has been previously described in
the literature, but was not obtained in pure form.
Specifically, Cp*Mo(PMe3)2(CO)H was generated as a
mixture with Cp*Mo(PMe3)(CO)2H upon reaction of:
(i) [Cp*Mo(CO)3(PMe3)]+ with LiAlH4; and (ii)
[Cp*Mo(CO)4]+ with LiAlH4 in the presence of PMe3
[2]. It is also important to note that the data reported
previously for Cp*Mo(PMe3)2(CO)H differ in some
significant ways from those reported here. For example:
(i) the 31P-NMR spectroscopic signal was reported as
19.6 ppm [2], rather than 29.8 ppm; and (ii) the 13C-
NMR spectroscopic signal for the carbonyl group was
reported as 275.0 ppm [2], rather than 253.3 ppm [3].
CO from
a
variety of substrates to form
Cp*Mo(PMe3)2(CO)H, a catalyst for decarboxylation
of formic acid.
* Corresponding author. Tel.: +1-212-8548247; fax: +1-212-
9321289.
E-mail address: parkin@chem.columbia.edu (G. Parkin).
Additional
characterization
for
the
Cp*Mo-
0022-328X/02/$ - see front matter © 2002 Published by Elsevier Science B.V.
PII: S0022-328X(01)01218-9

10
J.H. Shin et al. / Journal of Organometallic Chemistry 642 (2002) 9–15
(PMe3)2(CO)H as synthesized by reaction of
Cp*Mo(PMe3)3H with CO is provided by the forma-
tion of the iodide derivative Cp*Mo(PMe3)2(CO)I upon
reaction with MeI (Scheme 1).
Of more interest than forming Cp*Mo(PMe3)2(CO)H
by displacement of PMe3 with CO, Cp*Mo(PMe3)2-
(CO)H is also obtained upon reaction of
Cp*Mo(PMe3)3H with a variety of other reagents, in-
cluding, CO2, paraformaldehyde, MeOH, and HCO2H
(Scheme 1). For the reaction between Cp*Mo(PMe3)3H
1
and CO2, H-NMR spectroscopy demonstrates that the
formation of Cp*Mo(PMe3)2(CO)H is accompanied by
the generation of Me3PO, which helps provide the
driving force for the reaction. The formation of a
carbonyl complex upon reaction with CO2 is prece-
dented. For example, the reaction of Re(PMe3)5H with
CO2 yields the carbonyl complex Re(PMe3)4(CO)(h1-
O2CH), and the reactions of a variety of metal halides
with Na in PMe3 solvent under a CO2 atmosphere yield
carbonyl complexes, e.g. cis-Cr(PMe3)4(CO)2, Mo-
(PMe3)5(CO), W(PMe3)5(CO), and trans-Fe(PMe3)4-
(CO)2 [4]. Furthermore, h2-CO2 complexes are known
to decompose to carbonyl derivatives. For example,
Ni(PCy3)2(CO2) decomposes to Ni(PCy3)2(CO)2, while
Fe(PMe3)4(CO2) decomposes to Fe(PMe3)3(CO)(CO3)
[5].
Scheme 1.
It is also worth noting that the formation of a
carbonyl complex from CO2 is the reverse of a common
reaction that is typically used to displace CO from a
metal center. Specifically, reaction of a metal carbonyl
complex with R3NO is a common means of effecting
displacement of a carbonyl ligand as CO2 [6]. It is
therefore, postulated that the reaction between
Cp*Mo(PMe3)3H and CO2 involves initial displacement
Scheme 2.
of PMe3 and generation of
a
CO2 adduct,
Cp*Mo(PMe3)2(h2-CO2)H, which undergoes an oxygen
atom abstraction with the liberated PMe3 to yield the
carbonyl complex Cp*Mo(PMe3)2(CO)H (Scheme 2).
The ability of PMe3 to promote deoxygenation of CO2
and form a metal carbonyl complex, whereas R3NO
effects the opposite reaction, is presumably a conse-
quence of a stronger phosphine–oxide versus amine–
oxide bond [7].
The reaction of Cp*Mo(PMe3)3H with MeOH to
generate, inter alia, Cp*Mo(PMe3)2(CO)H is postulated
to occur via a sequence involving: (i) formation of a
methoxide derivative; (ii) dehydrogenation to a formal-
dehyde complex; (iii) conversion to a formyl-hydride
derivative; (iv) reductive-elimination of H2; and (v) a-H
elimination (Scheme 3). The transformation comprises
steps that are, in essence, the reverse of those required
for the metal catalyzed hydrogenation of carbon
monoxide and the formation of oxygenates in the Fis-
cher–Tropsch synthesis reaction [8]. An exemplary il-
lustration of dehydrogenation of a formaldehyde ligand
[9] to a carbonyl ligand is provided by the reaction of
Scheme 3.

J.H. Shin et al. / Journal of Organometallic Chemistry 642 (2002) 9–15
11
Precedent for the formation of [Cp*Mo(PMe3)3H2]+ is
provided by the observation that the analogous com-
plexes [CpMo(PMe3)3H2][BF4] [15] and [CpW(PMe3)3-
H2][BF4] [16] have been obtained by reactions of
CpM(PMe3)3H (M=Mo, W) with HBF4. Upon heat-
ing to 80 °C, however, [Cp*Mo(PMe3)3H2][HCO2] is
converted to the carbonyl complex Cp*Mo(PMe3)2-
(CO)H, accompanied by elimination of H2 and Me3PO.
The reaction is proposed to occur via reductive elimina-
tion of H2, followed by coordination of formate, to
yield Cp*Mo(PMe3)3(h1-O2CH). Subsequent dissocia-
tion of PMe3 and b-hydrogen elimination would gener-
ate the CO2 complex Cp*Mo(PMe3)2(h2-CO2)H
(Scheme 4). As suggested above, oxygen abstraction
from the coordinated CO2 by PMe3 would generate
Cp*Mo(PMe3)2(CO)H and Me3PO.
Although Cp*Mo(PMe3)2(CO)H is obtained by reac-
tion of Cp*Mo(PMe3)3H with one equivalent of
HCO2H, Cp*Mo(PMe3)2(CO)H reacts further with
HCO2H to generate an orange species that has been
1
characterized by H-NMR spectroscopy and mass spec-
trometry as Cp*Mo(PMe3)2(CO)(h1-O2CH). However,
upon heating to 80 °C, Cp*Mo(PMe3)2(CO)(h1-O2CH)
undergoes decarboxylation and regenerates Cp*Mo-
(PMe3)2(CO)H [17]. Thus, Cp*Mo(PMe3)2(CO)H serves
as a catalyst for the decomposition of HCO2H to CO2
and H2. The catalytic decomposition of formic acid is
the reverse of the commercially more important reduc-
tion of CO2 to formic acid, which has been widely
studied [18,19].
Scheme 4.
A
proposed, simplified, catalytic cycle for the
Cp*Mo(PMe3)2(CO)H mediated decarboxylation of
formic acid is illustrated in Scheme 5. In this regard, it
is worth noting that the iodide analogue Cp*Mo-
Scheme 5.
W(PMe3)4(h2-OCH2)H2 with a hydrogen acceptor (e.g.
propene) to give W(PMe3)4(CO)H2 [10–12]. Further-
more, an example of a-H elimination of a formyl
compound is provided by the facile conversion of
Cp*Mo(PPh3)(CO)2(CHO) to Cp*Mo(PPh3)(CO)2H at
−40 °C [13,14]. The formaldehyde and formyl com-
plexes are also postulated intermediates in the forma-
tion of Cp*Mo(PMe3)2(CO)H upon reaction of
Cp*Mo(PMe3)3H with paraformaldehyde (Scheme 3).
The reaction between Cp*Mo(PMe3)3H and HCO2H
has been studied by 1H-NMR spectroscopy, which indi-
cates that the initial interaction involves protonation of
the molybdenum center to give [Cp*Mo(PMe3)3-
H2][HCO2] (Scheme 4). The presence of two hydride
ligands in [Cp*Mo(PMe3)3H2]+ is confirmed by the
Fig. 1. Molecular Structure of Cp*Mo(PMe3)2(CO)(h1-O2CMe). Se-
,
lected bond lengths (A) and angles (°): MoꢀC(1) 1.874(9), MoꢀO(2)
2.167(4), MoꢀP(1) 2.462(2), MoꢀP(2) 2.454(2), C(1)ꢀO(1) 1.200(9),
C(2)ꢀO(2) 1.277(8), C(2)ꢀO(3) 1.212(8), C(2)ꢀC(3) 1.504(11);
C(1)ꢀMoꢀO(2)136.2(2), C(1)ꢀMoꢀP(1) 75.6(3), C(1)ꢀMoꢀP(2)
observation of
a triplet (JPꢀH=49 Hz) in the
75.7(2),
P(1)ꢀMoꢀP(2)
113.9(1),
O(2)ꢀMoꢀP(1)
80.4(1),
31P{1HꢀMe} selectively decoupled NMR spectrum.
O(2)ꢀMoꢀP(2) 81.4(1), MoꢀO(2)ꢀC(2) 138.6(5).

12
J.H. Shin et al. / Journal of Organometallic Chemistry 642 (2002) 9–15
(PMe3)2(CO)I is ineffective as a catalyst for the
decomposition of HCO2H, thereby clearly indicating
the important role that the hydride ligand plays in the
catalytic cycle. Support for the formation of
Cp*Mo(PMe3)2(CO)(h1-O2CH) is provided by the
observation that Cp*Mo(PMe3)2(CO)H reacts with
MeCO2H and EtCO2H to give Cp*Mo(PMe3)2-
(CO)(h1-O2CMe) and Cp*Mo(PMe3)2(CO)(h1-O2CEt),
respectively, and Cp*Mo(PMe3)2(CO)(h1-O2CMe) has
been structurally characterized by X-ray diffraction
(Fig. 1). In contrast to Cp*Mo(PMe3)2(CO)(h1-O2CH),
however, Cp*Mo(PMe3)2(CO)(h1-O2CMe) and Cp*-
Mo(PMe3)2(CO)(h1-O2CEt) are stable towards elimina-
tion of CO2 because b-alkyl elimination is generally less
favored than b-hydrogen elimination [20,21].
C17H34MoOP2: C, 49.5; H, 8.3. Found: C, 49.3; H,
7.9%. MS: m/z=414 [M+]. IR data (KBr disk, cm−1):
2968 (m), 2903 (s), 1773 (vs) [w(CꢁO)], 1701 (m)
[w(MoꢀH)], 1478 (w), 1422 (m), 1376 (m), 1295 (w),
1276 (m), 1027 (w), 936 (vs), 850 (w), 711 (m), 665 (m),
1
2
571 (w), 499 (w). H-NMR (C6D6): −6.85 [t, JPꢀH
=
2
78, 1H, MoH], 1.31 [d, JPꢀH=8, 18H, 2P(CH3)3], 1.91
1
[s, 15H, C5(CH3)5]. 13C-NMR (C6D6): 12.5 [q, JCꢀH
=
1
1
126, 5C, C5(CH3)5], 25.0 [dq, JCꢀH=127, JCꢀP=28,
6C, 2 P(CH3)3], 100.6 [s, 5C, C5(CH3)5], 253.3 [dt,
2
2JCꢀP=29, JCꢀH=3, 1C, CO]. 31P{1H}-NMR (C6D6):
29.8 [s].
3.3. Synthesis of Cp*Mo(PMe3)2(CO)I
A solution of Cp*Mo(PMe3)2(CO)H (50 mg, 0.12
mmol) in C6H6 (10 ml) was treated with excess CH3I
(350 mg, 2.47 mmol) and stirred at room temperature
(r.t.) for 2 h. After this period, the volatile components
were removed from the mixture, and the residue was
dried in vacuo to give Cp*Mo(PMe3)2(CO)I as an
orange solid. Anal. Calc. for C17H33IMoOP2: C, 37.9;
H, 6.2. Found: C, 37.8; H, 6.1%. MS: m/z=540 [M+].
IR data (KBr disk, cm−1): 2965 (m), 2904 (s), 1778 (vs)
[w(CꢁO)], 1477 (m), 1454 (m), 1421 (m), 1375 (s), 1297
(m), 1274 (s), 1095 (m), 1024 (s), 944 (vs), 851 (m), 802
(m), 717 (m), 665 (m), 579 (w), 559 (w), 524 (w).
3. Experimental
3.1. General considerations
All manipulations were performed using a combina-
tion of glovebox, high-vacuum or Schlenk techniques
[22]. Solvents were purified and degassed by standard
procedures and all commercially available reagents
were used as received, unless otherwise noted in the
experimental procedures. IR spectra were recorded as
KBr pellets or neat samples on Perkin–Elmer 1430 or
2
1H-NMR (C6D6): 1.48 [d, JPꢀH=8, 18H, 2P(CH3)3],
1600 spectrophotometers and are reported in cm−1
.
1.70 [s, 15H, C5(CH3)5]. 13C-NMR (C6D6): 12.1 [q,
1JCꢀH=127, 5C, C5(CH3)5], 20.3 [dq, 1JCꢀH=132,
1JCꢀP=24, 6C, 2P(CH3)3], 102.1 [s, 5C, C5(CH3)5],
Mass spectra were obtained on a Nermag R10-10 mass
spectrometer using chemical ionization (CH4) tech-
niques. Elemental analyses were measured using a
Perkin–Elmer 2400 CHN Elemental Analyzer. 1H-
NMR spectra were recorded on Varian VXR-200
(200.057 MHz), VXR-300 (299.943 MHz), and VXR-
400 (399.95 MHz) spectrometers. 13C- and 31P-NMR
spectra were recorded on a Varian VXR-300 spectrom-
2
271.0 [t, JCꢀP=34, 1C, CO]. 31P{1H}-NMR (C6D6):
7.2 [s].
3.4. Reaction of Cp*Mo(PMe3)3H with CO2
A solution of Cp*Mo(PMe3)3H (ca. 10 mg) in C6D6
(1 ml) was heated at 80 °C under CO2. 1H-NMR
spectroscopy showed the formation of Cp*Mo(CO)-
(PMe3)2H (ca. 70%) and Me3PO after 1 day.
1
eter. H and 13C chemical shifts are reported in ppm
relative to SiMe4 (l=0) and were referenced internally
with respect to the protio solvent impurity (l=7.15 for
C6D5H and l=7.26 for CHCl3) and the 13C resonances
(l=128.0 for C6D6 and l=77.0 for CDCl3), respec-
tively. 31P-NMR chemical shifts are reported in ppm
relative to 85% H3PO4 (l=0) and were referenced
using P(OMe)3 (l=141.0) as external standard. All
coupling constants are reported in Hz. Cp*Mo-
(PMe3)3H was obtained by the literature method [1].
3.5. Reaction of Cp*Mo(PMe3)3H with (CH2O)n
A mixture of Cp*Mo(PMe3)3H (ca. 10 mg) and
paraformaldehyde (ca. 10 mg) in C6D6 (1 ml) was
heated at 80 °C. 1H-NMR spectroscopy showed the
formation of Cp*Mo(PMe3)2(CO)H (ca. 40%) inter
alia. Prolonged heating resulted in subsequent reaction
of Cp*Mo(PMe3)2(CO)H with paraformaldehyde to
form an unidentified complex.
3.2. Synthesis of Cp*Mo(PMe3)2(CO)H
A solution of Cp*Mo(PMe3)3H (100 mg, 0.22 mmol)
in C6H6 (10 ml) was treated with CO (1 atm) for 4 days
at 80 °C. After this period, the volatile components
were removed from the mixture, and the residue was
dried in vacuo to give Cp*Mo(PMe3)2(CO)H as a
brown solid (85 mg, 95%). Anal. Calc. for
3.6. Reaction of Cp*Mo(PMe3)3H with MeOH
A solution of Cp*Mo(PMe3)3H (ca. 10 mg) in C6D6
(1 ml) was treated with MeOH (ca. 10 mg) heated at

J.H. Shin et al. / Journal of Organometallic Chemistry 642 (2002) 9–15
13
1
1
80 °C. H-NMR spectroscopy showed the formation of
(C6D6): 19.5 [s]. 13C-NMR (C6D6): 11.6 [q, JCꢀH=127,
1
Cp*Mo(PMe3)2(CO)H (ca. 60%) as a major product
over a period of 2 days.
5C, C5(CH3)5], 18.0 [qm, JCꢀH=130, 6C, 2P(CH3)3],
26.6 [q, 1JCꢀH=126, 1C, O2CCH3], 103.7 [s, 5C,
3
C5(CH3)5], 176.1 [t, JPꢀC=2, 1C, O2CCH3], CO [not
3.7. Synthesis of [Cp*Mo(PMe3)3H2][HCO2]
located]. IR data (in pentane): 1802 [w(CꢁO)], 1623
[w(CꢂO)]. MS: m/z=472 [M+].
A solution of Cp*Mo(PMe3)3H (64 mg, 0.14 mmol)
in pentane (10 ml) was treated with a solution of
HCO2H (6 mg, 0.20 mmol) in pentane (5 ml). The
mixture was filtered after stirring for 2 h at r.t., and the
residue was washed with pentane (2×5 ml) and dried
in vacuo to give [Cp*Mo(PMe3)3H2][HCO2] as a pale
3.11. Reaction of Cp*Mo(PMe3)2(CO)H with EtCO2H
A solution of Cp*Mo(PMe3)2(CO)H (ca. 10 mg) in
C6D6 (1 ml) was treated with EtCO2H (10 mg) at
1
120 °C. H-NMR spectroscopy demonstrated that the
1
brown solid (30 mg, 43%). H-NMR (C6D6): −4.94
formation of Cp*Mo(PMe3)2(CO)(h1-O2CEt) as a ma-
[br. q, 2JPꢀH=49, 2H, 2MoH], 1.16 [m, 27H,
3P(CH3)3], 1.46 [s, 15H, C5(CH3)5], 9.43 [s, 1H, HCO2].
jor product (ca. 80%) was complete within 1 day.
3
1H-NMR (C6D6): 1.22 [t, JHꢀH=7, 3H, O2CCH2CH3],
1
31P{1H}-NMR (C6D6): 2.6 [s]. 31P{selective H–Me}-
1.28 [d, 2JPꢀH=9, 18H, 2P(CH3)3], 1.65 [s, 15H,
2
3
NMR (C6D6): 2.6 [t, JPꢀH=49]. IR data (KBr disk,
C5(CH3)5], 2.27 [q, JHꢀH=7, 2H, O2CCH2CH3]. 13C-
cm−1): 1946 [w(MoꢀH)], 1662 [w(CꢂO)].
NMR (C6D6): 11.7 [q, JCꢀH=127, 5C, C5(CH3)5], 11.7
1
1
1
[q, JCꢀH=126, 1C, O2CCH2CH3], 17.9 [qm, JCꢀH
=
3.8. Con6ersion of [Cp*Mo(PMe3)3H2][HCO2] to
Cp*Mo(PMe3)2(CO)H
132, 6C, 2P(CH3)3], 33.1 [q, 1JCꢀH=125, 1C,
O2CCH2CH3], 103.7 [s, 5C, C5(CH3)5], 180.0 [s, 1C,
O2CCH2CH3], CO [not located]. 31P{1H}-NMR
(C6D6): 19.3 [s]. IR data (in pentane): 1802 [w(CꢁO)],
1622 [w(CꢂO)].
A solution of [Cp*Mo(PMe3)3H2][HCO2] (ca. 10 mg)
in C6D6 (1 ml) was heated at 80 °C overnight. The
reaction was monitored by 1H-NMR spectroscopy
which demonstrated the formation of Cp*Mo(PMe3)2-
(CO)H (ca. 70%), Me3PO and H2 after 1 day.
3.12. X-ray structure determination of
Cp*Mo(PMe3)2(CO)(p1-O2CMe)
3.9. Reacti6ity of Cp*Mo(PMe3)2(CO)H towards
HCO2H
X-ray diffraction data were collected on a Bruker P4
diffractometer equipped with a SMART CCD detector
and crystal data, data collection and refinement
parameters are summarized in Table 1. The structure
was solved using direct methods and standard differ-
ence map techniques, and were refined by full-matrix
least-squares procedures on F2 with SHELXTL (Version
5.03) [23]. Hydrogen atoms on carbon were included in
calculated positions.
A solution of Cp*Mo(PMe3)2(CO)H (ca. 10 mg) in
C6D6 (1 ml) was treated with HCO2H (20 mg) at r.t.
The pale yellow solution immediately changed to or-
ange giving initially Cp*Mo(PMe3)2(CO)(h1-O2CH),
which subsequently decomposed to Cp*Mo(PMe3)2-
(CO)H when all the HCO2H originally present was
converted to CO2 and H2. 1H-NMR for
Cp*Mo(PMe3)2(CO)(h1-O2CH) (C6D6): 1.11 [d,
2JPꢀH=8, 18H, 2P(CH3)3], 1.52 [s, 15H, C5(CH3)5], 8.61
4. Summary
4
[t, JPꢀH=2, 1H, O2CH]. 31P{1H}-NMR (C6D6): 18.3
[s]. MS: m/z=458 [M+]. The formate complex is only
observed in the presence of free HCO2H. Also, if the
reaction is carried out at 80 °C, the formic acid is
catalytically decomposed to CO2 and H2 within 1 day.
In conclusion, Cp*Mo(PMe3)3H undergoes carbonyl
abstraction reactions with a variety of reagents, includ-
ing CO2, (CH2O)n, MeOH and HCO2H to yield
Cp*Mo(PMe3)2(CO)H, which is a catalyst for the de-
carboxylation of HCO2H to CO2 and H2.
3.10. Reaction of Cp*Mo(PMe3)2(CO)H with
MeCO2H
5. Supplementary material
A solution of Cp*Mo(PMe3)2(CO)H (ca. 10 mg) in
C6D6 (1 ml) was treated with MeCO2H (10 mg) at
80 °C. 1H-NMR spectroscopy demonstrated that the
quantitative formation of Cp*Mo(PMe3)2(CO)(h1-
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 166448 for compound
Cp*Mo(PMe3)2(CO)(h1-O2CMe). Copies of this infor-
mation may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2
1
O2CMe) was complete within 1 day. H-NMR (C6D6):
1.25 [d, 2JPꢀH=8, 18H, 2P(CH3)3], 1.60 [s, 15H,
C5(CH3)5], 2.07 [s, 3H, O2CCH3]. 31P{1H}-NMR

14
J.H. Shin et al. / Journal of Organometallic Chemistry 642 (2002) 9–15
Table 1
Crystal,
(h) A.M. Kelly, G.P. Rosini, A.S. Goldman, J. Am. Chem. Soc.
119 (1997) 6115–6125.
intensity
collection
and
refinement
data
for
Cp*Mo(PMe3)2(CO)(h1-O2CMe)
[7] For example, the EꢀO bond dissociation energies in Ph3PO and
C5H5NO are 133 and 72 kcal mol−1, respectively. See: R.H.
Holm, J.P. Donahue, Polyhedron 12 (1993) 571–589.
[8] See for example: (a) M.J. Overett, R.O. Hill, J.R. Moss, Coord.
Chem. Rev. 206–207 (2000) 581–605;
(b) M.E. Dry, App. Cat. A 138 (1996) 319–344.
[9] For a brief review of aldehyde complexes, see: Y.-H. Huang, J.Z.
Gladysz, J. Chem. Edu. 65 (1988) 298–303.
Cp*Mo(PMe3)2(CO)(h1-O2CMe)
Lattice
Orthorhombic
C
470.36
Pbca
14.709(1)
10.048(1)
31.672(2)
90
90
90
4680.9(6)
8
238
0.71073
1.335
0.711
28.3
Empirical formula
Formula weight
Space group
19H36O3P2Mo
,
a (A)
[10] M.L.H. Green, G. Parkin, J. Chem. Soc. Chem. Commun.
(1986) 90–91.
,
b (A)
,
c (A)
[11] Other examples of the conversion of h2-formaldehyde complexes
into carbonyl derivatives are provided by the decomposition of
h (°)
i (°)
k (°)
Os(PPh3)2(CO)2(h2-OCH2)
to
Os(PPh3)2(CO)3
via
Os(PPh3)2(CO)2(CHO)H (a,b) and the decomposition of
Cp*Rh[P(OMe)3](h2-OCH2) to Cp*Rh[P(OMe)3](CO) (c). (a)
K.L. Brown, G.R. Clarke, C.E.L. Hedford, K. Marsden, W.R.
Roper, J. Am. Chem. Soc. 101 (1979) 503–505;
(b) G.R. Clarke, C.E.L. Hedford, K. Marsden, W.R. Roper, J.
Organomet. Chem. 231 (1982) 335–360;
3
,
V (A )
Z
Temperature (K)
,
Radiation (u, A)
Dcalc (g cm−3
)
v (Mo–Ka) (mm−1
q maximum (°)
)
(c) H. Werner, M. Steinmetz, K. Peters, H.G. von Schnering,
Eur. J. Inorg. Chem. (1998) 1605–1617.
Number of data
5468
[12] Of further relevance, [Co(PMe3)4][PF6] reacts with formaldehyde
to give the carbonyl complex [Co(CO)(PMe3)4][PF6] (a). In con-
trast the Ir complex gives [Ir(PMe3)4(CHO)H]+ (b). (a) Y. Peres,
M. Dartiguenave, Y. Dartiguenave, J.F. Britten, A.L.
Beauchamp, Organometallics 9 (1990) 1041–1047;
Number of parameters
R1
wR2
Goodness-of-fit
239
0.0715
0.1556
1.071
(b) D.L. Thorn, Organometallics 1 (1982) 197–204.
[13] P. Leoni, E. Aquilini, M. Pasquali, F. Marchetti, M. Sabat, J.
Chem. Soc. Dalton. Trans. (1988) 329–333.
[14] For further examples of the decomposition of related formyl
complexes, see: (a) D.H. Gibson, K. Owens, S.K. Mandal, W.E.
Sattich, J.O. Franco, Organometallics 8 (1989) 498–505;
(b) A. Asdark, C. Lapinte, L. Toupet, Organometallics 8 (1989)
2708–2717;
1EZ, UK (Fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgements
(c) P. Leoni, A. Landi, M. Pasquali, J. Organomet. Chem. 321
(1987) 365–369.
[15] M. Brookhart, K. Cox, F.G.N. Cloke, J.C. Green, M.L.H.
Green, P.M. Hare, J. Bashkin, A.E. Derome, P.D. Grebenik, J.
Chem. Soc. Dalton. Trans. (1985) 423–433.
We thank the US Department of Energy, Office of
Basic Energy Sciences (DE-FG02-93ER14339) for sup-
port of this research. The reviewers are gratefully
thanked for valuable suggestions.
[16] M.L.H. Green, G. Parkin, J. Chem. Soc. Dalton. Trans. (1987)
1611–1617.
[17] Elimination of CO2 from formate complexes to yield a hydride
derivative is precedented. For example, Re(PMe3)4(CO)(h1-
O2CH) eliminates CO2 at 70 °C to yield Re(CO)(PMe3)4H; the
elimination CO2 is reversible and Re(CO)(PMe3)4H reacts with
CO2 to regenerate Re(PMe3)4(CO)(h1-O2CH) (Ref. [4]). A futher
recent example of CO2 insertion into a MꢀH bond is provided by
the reaction of mer-Mo(PMe3)3(CO)(NO)H with CO2 to give
mer-Mo(PMe3)3(CO)(NO)(h1-O2CH). See: F. Liang, H. Jacob-
sen, H.W. Schmalle, T. Fox, H. Berke, Organometallics 19
(2000) 1950–1962.
[18] E. Dinjus, R. Fornica, in: B. Cornils, W.A. Herrmann (Eds.),
Applied Homogeneous Catalysis with Organometallic Com-
pounds, vol. 2, 1996, pp. 1048–1072.
[19] For recent theoretical studies on the decarboxylation of formic
acid, see: B. Wang, H. Hou, Y. Gu, J. Phys. Chem. A 104 (2000)
10526–10528.
References
[1] J.H. Shin, G. Parkin, Polyhedron 13 (1994) 1489–1493.
[2] M.-J. Tudoret, M.-L. Robo, C. Lapinte, Organometallics 11
(1992) 1419–1422.
[3] The formula for Cp*Mo(PMe3)2(CO)H for which the analysis
was calculated in Ref. [2] was erroneously given as
C15H25MoO2P, rather than C17H34MoOP2.
[4] D.L. Allen, M.L.H. Green, J.A. Bandy, J. Chem. Soc. Dalton.
Trans. (1990) 541–549.
[5] D.H. Gibson, Chem. Rev. 96 (1996) 2063–2095.
[6] (a) H. Alper, J.T. Edward, Can. J. Chem. 48 (1970) 1543–1549;
(b) Y. Shvo, E. Hazum, J. Chem. Soc. Chem. Commun. (1974)
336–337;
(c) U. Koelle, J. Organomet. Chem. 155 (1978) 53–62;
(d) U. Koelle, J. Organomet. Chem. 133 (1977) 53–58;
(e) M.O. Albers, N.J. Coville, Coord. Chem. Rev. 60 (1984)
255–276;
(f) J.K. Shen, Y.-C. Gao, Q.-Z. Shi, F. Basolo, Coord. Chem.
Rev. 128 (1993) 69–88;
[20] G. Parkin, E. Bunel, B.J. Burger, T.S. Trimmer, A. van Asselt,
J.E. Bercaw, J. Mol. Catal. 41 (1987) 21–39.
[21] Decarboxylation of certain carboxylates, such as MꢀO2CCH2CN
and MꢀO2C(CH2)nCO2H (n=1, 2), is, nevertheless known. See:
(a) T. Tsuda, T. Nakatsuka, T. Hirayama, T. Seagusa, J. Chem.
Soc. Chem. Commun. (1974) 557–558;
(g) T.Y. Luh, Coord. Chem. Rev. 60 (1984) 255–276;

J.H. Shin et al. / Journal of Organometallic Chemistry 642 (2002) 9–15
15
(b) D.J. Darensbourg, E.M. Longridge, M.W. Holtcamp, K.K.
Klausmeyer, J.H. Reibenspies, J. Am. Chem. Soc. 115 (1993)
8839–8840;
M.Y. Darenbourg (Eds.), Experimental Organometallic Chem-
istry, American Chemical Society, Washington DC, 1987, pp.
6–23 Chapter 2;
(c) D.J. Darensbourg, E.M. Longridge, M.W. Holtcamp, E.V.
Atnip, J.H. Reibenspies, Inorg. Chem. 30 (1991) 357–358;
(d) D.J. Darensbourg, M.W. Holtcamp, B. Khandelwal, J.H.
Reibenspies, Inorg. Chem. 33 (1994) 531–537;
(e) D.J. Darensbourg, E.M. Longridge, B. Khandelwal, J.H.
Reibenspies, J. Coord. Chem. 32 (1994) 27–37;
(b) B.J. Burger, J.E. Bercaw, in: A.L. Wayda, M.Y. Darenbourg
(Eds.), Experimental Organometallic Chemistry, American
Chemical Society, Washington DC, 1987, pp. 79–98 Chapter 4;
(c) D.F. Shriver, M.A. Drezdzon, in: The Manipulation of
Air-Sensitive Compounds, 2nd ed., Wiley-Interscience, New
York, 1986.
(f) D.J. Darensbourg, M.W. Holtcamp, B. Khandelwal, K.K.
Klausmeyer, J.H. Reibenspies, Inorg. Chem. 34 (1995) 2389–
2398.
[23] Sheldrick, G.M., SHELXTL, An Integrated System for Solving,
Refining and Displaying Crystal Structures, from Diffraction
Data; University of Go¨ttingen, Go¨ttingen, Federal Republic of
Germany, 1981.
[22] (a) J.P. McNally, V.S. Leong, N.J. Cooper, in: A.L. Wayda,