Geometrical isomerization of fac/mer-Mo(CO)3(phosphite)3 and cis/trans-Mo(CO)4(phosphite)2 catalyzed by Me3SiOSO2CF3

Article abstract of DOI:10.1016/j.jorganchem.2008.02.024

Geometrical isomerization of fac-Mo(CO)₃L₃ (L = P(OPh)₃, P(OMe)₃, P(OEt)₃) to the mer form and that of cis-Mo(CO)₄L₂ (L = P(OPh)₃, P(OMe)₃, PPh₂(OMe)) to the trans form were observed in CH₂Cl₂ at room temperature in the presence of a catalytic amount of Me₃SiOSO₂CF₃ (TMSOTf). Crossover experiments suggest that a ligand dissociation is not involved in the isomerization. A catalytic cycle involving an interaction of the silicon atom in Me₃Si⁺ with one oxygen in P(OR)₃ ligands has been proposed. The first isolation and the X-ray structure analysis were attained for mer-Mo(CO)₃{P(OPh)₃}₃ through the TSMOTf-assisted isomerization of fac-Mo(CO)₃{P(OPh)₃}₃.

Full text of DOI:10.1016/j.jorganchem.2008.02.024

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 1968–1974
www.elsevier.com/locate/jorganchem
Geometrical isomerization of fac/mer-Mo(CO)3(phosphite)3 and
cis/trans-Mo(CO)4(phosphite)2 catalyzed by Me3SiOSO2CF3
Kozo Fukumoto, Hiroshi Nakazawa *
Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
Received 16 January 2008; received in revised form 18 February 2008; accepted 21 February 2008
Available online 4 March 2008
Abstract
Geometrical isomerization of fac-Mo(CO)3L3 (L = P(OPh)3, P(OMe)3, P(OEt)3) to the mer form and that of cis-Mo(CO)4L2
(L = P(OPh)3, P(OMe)3, PPh2(OMe)) to the trans form were observed in CH2Cl2 at room temperature in the presence of a catalytic
amount of Me3SiOSO2CF3 (TMSOTf). Crossover experiments suggest that a ligand dissociation is not involved in the isomerization.
A catalytic cycle involving an interaction of the silicon atom in Me3Si+ with one oxygen in P(OR)3 ligands has been proposed. The first
isolation and the X-ray structure analysis were attained for mer-Mo(CO)3{P(OPh)3}3 through the TSMOTf-assisted isomerization of
fac-Mo(CO)3{P(OPh)3}3.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: Geometrical isomerization; Catalysis; Mo complex; Phosphite
1. Introduction
metal complexes; M(bpy)(CO)3{P(NMeCH2)2(OR)} [6–
12], M(dppe)(CO)3{P(NMeCH2)2(OR)} [7], M(bpy)-
(CO)2{P(NMeCH2)2(OR)}2 [8,11,12], M(CO)3{P(NMe-
CH2)2(OR)}3 [13], M(CO)4{P(NMeCH2)2(OR)}2 [13],
CpM(CO)2(ER3){P(NMeCH2)2(OR)} (M = Cr, Mo, W)
[14–17], and CpM(CO)(ER3){P(NMeCH2)2(OR)} (M =
Fe, Ru) (ER3 = CH3, SiMe3, GeMe3, SnMe3) [10,18–23].
Systematic researches for reactions of Mo(bpy)-
(CO)3{PXY(OR)} with BF3 ꢀ OEt2 revealed the effect of
the substituents (X, Y) on the stability of cationic phosphe-
nium complexes; the stability increases with increasing the
number of amino substituents on the phosphenium phos-
phorus [9]. TMSOTf has been demonstrated to be an
appropriate Lewis acid for fac-Mo(CO)3{P(NMe-
CH2)2(OR)}3 and cis-Mo(CO)4{P(NMeCH2)2(OR)}2 [13].
During the course of investigation of suitability of a Lewis
acid to yield a cationic phosphenium complex by OR anion
abstraction, we obtained unexpected results in the reaction
with TMSOTf of fac-Mo(CO)3{P(OR)3}3 and cis-
Mo(CO)4{P(OR)3}2 having no amino-substituent on the
coordinating phosphites; TMSOTf does not abstract an
Transition metal complexes with
a phosphenium
ligand (+PR2) have attracted considerable attention
because a cationic phosphenium is isolobal with a singlet
carbene, silylene, and the heavier congeners [1–5]. One of
the best methods for preparation of cationic phospheni-
um complexes of transition metals is OR anion abstrac-
tion by a Lewis acid such as BF3 ꢀ OEt2 or TMSOTf
(Me3SiOSO2CF3) from coordinating diamino-substituted
phosphite P(NMeCH2)2(OR) as shown in Eq. (1) [4,5].
This method is applicable for many types of transition
+
N
Lewis acid
OR-
N
N
ð1Þ
M
P
M
P
N
OR
*
Corresponding author.
E-mail address: nakazawa@osaka-cu.ac.jp (H. Nakazawa).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.02.024

K. Fukumoto, H. Nakazawa / Journal of Organometallic Chemistry 693 (2008) 1968–1974
1969
OR anion to give a cationic phosphenium complex, but pro-
2.2. Reaction of fac-Mo(CO)3L3 with TMSOTf
motes the geometrical isomerization of the complexes (fac–
mer and cis–trans isomerization), and it works as a catalyst.
The Mo(CO)3L3 complexes (M = Cr, Mo, W; L = phos-
phine, phosphite) have been synthesized in the facial form
from MðCOÞ3L03 (L0 = weekly coordinating 2e-donor
ligand) and L. The mer isomers were obtained by using
isomerization of the corresponding fac isomers. Bond
et al. reported that a one electron-oxidation promotes
fac–mer isomerization for M(CO)3{Ph2PCH2CH2-
P(Ph)CH2CH2P Ph2-j3P} [24]. We reported that the reac-
tion of fac-M(CO)3(bpy){P(NMeCH2)2(OMe)} with
BF3 ꢀ OEt2 yields a cationic phosphenium complex, fac-
[M(CO)3(bpy){P(NMeCH2)2}]+, which then isomerizes to
the mer form [7–9]. The strong p-acidity of a phosphenium
ligand causes an electron deficient metal center which may
induce the fac–mer isomerization. Thermal fac–mer isomer-
ization has been reported by Rousche et al. for fac-
Mo(CO)3(g2-dppe){P(OiPr)3} [25] and by Howell et al.
for fac-M(CO)3{P(OR)3}3 [26]. We recently found that
Me3SiX (X = Cl, Br, I) promotes the fac–mer isomeriza-
tion for fac-Mo(CO)3{P(OR)3}3 [27].
The fac-Mo(CO)3{P(OPh)3}3 (fac-1) was dissolved in
CH2Cl2 and an equimolar amount of TMSOTf was added
at room temperature and the reaction was monitored by
the 31P NMR measurement. A triplet at 148.2 ppm
2
2
(t, JPP = 47.0 Hz) and a doublet at 155.2 ppm (d, JPP
=
47.0 Hz) were newly observed at the expense of a singlet
at 144.4 ppm attributed to fac-1. The new signals were rea-
sonably assigned to mer-1 based on their coupling pattern
and the coupling constant. The isomerization reached at an
equilibrium after 1.5 h and the fac-1:mer-1 ratio was 1: 30.
We confirmed that fac-1 did not isomerize to mer-1 in
CH2Cl2 in the absence of TMSOTf at room temperature
and even at the reflux temperature, showing that TMSOTf
promotes its isomerization. Next question is whether
TMSOTf works as a catalyst or not. The reactions of
fac-1 with 0.5 and 0.1 equivalent of TMSOTf revealed that
the final equilibrium position did not depend on the
amount of TMSOTf used although it took a longer time
to reach the equilibrium when the amount of TMSOTf
was reduced.
The mer-1 could be isolated from the reaction mixture of
fac-1 and TMSOTf. After a treatment of fac-1 with
TMSOTf in CH2Cl2, a white powder which is a mixture
of fac-1 and mer-1 (1:30) was washed with hexane/
CH2Cl2/benzene (100/1/1) solution many times to obtain
the pure complex formulated as mer-1 ꢀ 0.5CH2Cl2 ꢀ
0.5C6H6 in 53% yield. Although several mer-M(CO)3L3
(M = Cr, Mo, W) type complexes have been reported, this
is the first preparation and isolation of mer-
M(CO)3{P(OPh)3}3. The structure was confirmed by the
X-ray analysis. The ORTEP drawing is depicted in Fig. 1
and the crystal data are summarized in Table 1. This
X-ray structure is the first example among mer-
M(CO)3(tertiary phosphorus compound)3 type complexes.
The X-ray structure of fac-1 was reported previously [29].
The structural comparison between fac- and mer-
Mo(CO)3{P(OPh)3}3 revealed some interesting points.
2. Results and discussion
2.1. Preparation of fac-Mo(CO)3{P(OR)3}3 and
cis-Mo(CO)4{P(OR)3}2
The fac-Mo(CO)3{P(OR)3}3 complexes were obtained
in good yield by modifying the literature methods [28].
Mo(CO)3(NCMe)3 was treated with P(OR)3 in 1:3 molar
ratio in THF at room temperature (Eq. (2)). A preparative
method for cis-Mo(CO)4{P(OR)3}2 was briefly described in
the literature, where Mo(CO)4(NMe2(CH2)3NMe2) was
used as an Mo source [29]. We modified the starting com-
plex. Mo(CO)4(nbd) (nbd = norbornadiene) and P(OR)3
were treated in 1:2 molar ratio in CH2Cl2 at room temper-
ature to give cis-Mo(CO)4{P(OR)3}2 in excellent yield (Eq.
(3)).
˚
The bond distance of Mo–C2 for mer-1 (2.018 A) is clearly
Me
C
˚
shorter than those of Mo–C1 (2.041 A) and Mo–C3
L
˚
N
(2.041 A). As C2O2 ligand is trans to P(OPh)3, the CO
O
Me
O
C
C
C
in THF
at r.t.
L
L
N
ligand can get more p-back donation from the central
+
Mo
3L
Mo
metal than C1O1 and C3O3 ligands which are mutually
C
C
N
O
O
ð2Þ
ð3Þ
C
˚
Me
trans. The mean Mo–C bond distance for fac-1 (1.986 A)
C
O
C
O
˚
is shorter than that for mer-1 (2.033 A), reasonably under-
L = P(OPh)3 Yield: 82%
stood by greater p-back donation from the Mo to the CO
ligands for fac-1 because of the trans P(OPh)3 ligand.
Another interesting point is that the mean Mo–P bond dis-
P(OMe)3
P(OEt)3
92%
92%
O
C
O
C
˚
tance for fac-1 (2.435 A) is longer than that for mer-1
˚
O
C
(2.417 A). The difference may stem from the steric repul-
O
in CH2Cl2
at r.t.
C
L
Mo
+ 2L
Mo
sion between P(OPh)3 ligands in fac-1.
C
O
C
L
O
The mer-1 did not isomerize to fac-1 in CH2Cl2 at room
temperature, but it did by the addition of an equimolar
amount or even a catalytic amount of TMSOTf. After sev-
eral hours, the fac-1:mer-1 ratio was 1:30. The results men-
tioned above show that the equilibrium ratio is determined
C
O
C
O
L = P(OPh)3 Yield: 92%
P(OMe)3
PPh2(OMe)
96%
96%

1970
K. Fukumoto, H. Nakazawa / Journal of Organometallic Chemistry 693 (2008) 1968–1974
2
170.5 ppm (d, JPP = 41.7 Hz) attributable to mer-3 were
observed in the reaction of fac-3. The equilibrium fac–
mer ratios were independent of the amount of TMSOTf
used, showing that TMSOTf serves as a catalyst. The
results together with those for fac-1 are shown in Table
2. The equilibrium fac–mer ratios are quite dependent on
the kind of the phosphite ligand. It should be noted that
these values are equal to those for the isomerization pro-
moted by Me3SiX (X = Cl, Br, I) [27], and the value for
fac-2 is similar to that reported by Howell [26]. Therefore,
it can be said that the values are derived from the thermo-
dynamic stability between the fac and mer isomers, not
from the stability of the intermediates created from an
Mo complex and a catalyst (presumably TMS+, vide infra).
2.3. Isomerization mechanism
Regarding isomerization of Mo(CO)3{P(OR)3}3 pro-
moted by TMSOTf, two mechanisms are conceivable:
mechanisms via a phosphenium complex and via a TMS+
adduct.
Fig. 1. ORTEP drawing of mer-1 ꢀ 0.5CH2Cl2 ꢀ 0.5C6H6 (50% probability
ellipsoids) showing the numbering system. All hydrogen atoms and the
solvated CH2Cl2 and C6H6 molecules are omitted for clarity. Selected
A mechanism via a phosphenium complex is shown in
Scheme 1. As transition-metal complexes bearing a dia-
mino-substituted phosphite have been reported to react
with a Lewis acid to give cationic phosphenium complexes
by ORꢁ abstraction as shown in Eq. (1), a similar ORꢁ
abstraction may take place in the reaction of Mo(CO)3
{P(OR)3}3 with TMSOTf to produce a cationic phospheni-
um complex (fac0 in Scheme 1). Then, isomerization from
fac0 to mer0 is expected to take place. The similar isomeri-
zation has been reported previously (Eq. (4)), where the
driving force of the fac–mer isomerization is thought to
be the gain of more p-back donation for the phosphenium
ligand. The reaction of mer0 with TMSOR formed would
give mer-Mo(CO)3{P(OR)3}3 with regeneration of
TMSOTf. However, this catalytic cycle seems not plausible
based on the following observations. (i) A complex having
a phosphenium ligand was not detected in the reaction of
Mo(CO)3{P(OR)3}3 with TMSOTf. (ii) After the treatment
˚
bond distances (A) and bond angles (°): Mo1–P1, 2.3796(7); Mo1–P2,
2.4319(7); Mo1–P3, 2.4390(7); Mo1–C1, 2.041(3); Mo1–C2, 2.018(3);
Mo1–C3, 2.041(3); P1–Mo1–P2, 174.24(2); P1–Mo1–P3, 89.76(2); P2–
Mo1–P3, 89.57(2); P1–Mo1–C1, 91.21(8), P1–Mo–C2, 86.15(8); P1–Mo–
C3, 91.51(8).
Table 1
Crystal data for mer-1 ꢀ 0.5CH2Cl2 ꢀ 0.5C6H6
Empirical formula
Formula weight
Crystal system
Crystal size (mm3)
Temperature (°C)
Space group
C60.50H49ClMoO12P3
1192.30
Monoclinic
0.45 ꢂ 0.35 ꢂ 0.15
ꢁ70.0
P21/n (No. 14)
13.7319(5)
18.2658(7)
22.1401(9)
95.744(2)
5525.4(4)
4
˚
a (A)
˚
b (A)
˚
c (A)
b (°)
3
˚
V (A )
Z
l (cmꢁ1
)
4.36
1.433
Dcalc (g/cm3)
Table 2
Number of unique reflections
Number of used reflections
Number of variables
R
41908
12498
712
0.051
0.111
1.06
Isomerization of Mo(CO)3{P(OR)3}3 by TMSOTf in CH2Cl2 at room
temperature
P(OR)3
P(OR)3
P(OR)3
RW
Goodness-of-Fit
O
O
TMSOTf a
C
C
P(OR)3
Mo
Mo
C
C
C
P(OR)3
O
O
O
thermodynamically and TMSOTf serves as a catalyst for
the fac–mer isomerization.
C
O
P(OR)3
Reactions of fac-Mo(CO)3{P(OMe)3}3 (fac-2) and fac-
Mo(CO)3{P(OEt)3}3 (fac-3) with TMSOTf were also exam-
ined in CH2Cl2 at room temperature. In the 31P NMR
P(OR)3
P(OPh)3
P(OMe)3
P(OEt)3
a
fac:merb
fac-1
fac-2
fac-3
mer-1
mer-2
mer-3
1:30
1:3.4
1:2.2
2
spectra, a triplet at 166.9 ppm (t, JPP = 41.7 Hz) and a
2
doublet at 175.1 ppm (d, JPP = 41.7 Hz) assignable to
mer-2 were observed in the reaction of fac-2, and a triplet
1.0, 0.5 and 0.1 equvalents based on the fac complex were used.
fac:mer equilibrium ratio after completion of the isomerization.
2
b
at 162.7 ppm (t, JPP = 41.7 Hz) and a doublet at

K. Fukumoto, H. Nakazawa / Journal of Organometallic Chemistry 693 (2008) 1968–1974
1971
P(OR)3
P(OR)3
P(OR)3
P(OR)3
P(OR)3
P(OR)3
O
O
C
O
O
C
C
TMSOTf
TMSOTf
C
P(OR)3
P(OR)3
P(OR)3
P(OR)3
Mo
Mo
Mo
P(OR)3
mer
Mo
P(OR)3
mer
C
C
C
C
C
C
O
O
O
O
O
O
C
O
C
O
fac
fac
TMSOTf
TMSOR
TMSOTf
+
+
+
+
P(OR)3
P(OR)3
P(OR)3
P(OR)3
OTf
OTf
OTf
OTf
O
O
C
O
O
C
C
C
P(OR)3
OR
P(OR)3
OR
OR
P(OR)3
P(OR)3
Mo
Mo
Mo
P
Mo
P
P
P
C
C
C
C
C
O
C
O
O
O
O
O
C
O
C
O
OR
OR
OR
OR
RO
RO
TMS
mer''
OR
TMS
fac'
mer'
fac''
Scheme 1.
Scheme 2.
Both fac-2 and fac-3 were dissolved in CH2Cl2, TMSOTf
was added, and the products were estimated from the 31P
NMR spectra of the resulting CH2Cl2 solution. Signals
assignable to mer-2 and mer-3, in addition to fac-2 and
fac-3 were observed, but those due to phosphite exchange
products such as fac- or mer-Mo(CO)3{P(OMe)3}2-
{P(OEt)3} and OR exchange products such as fac- or
of fac-1 with 1 equiv of TMSOTf in the presence of 1 equiv
of TMSOMe in CH2Cl2, the 31P NMR spectra of the reac-
tion mixture were measured and fac-1 and mer-1 were
detected but fac- and mer-Mo(CO)3{P(OPh)3}2{P(O-
Ph)2(OMe)} were not detected at all. This indicates that
the reaction of mer0 with TMSOR to give mer in Scheme
1 does not proceed.
mer-Mo(CO)3{P(OMe)3}2{P(OMe)2(OEt)}
were
not
detected. These results strongly suggest that neither phos-
phite dissociation nor ORꢁ abstraction shown in Scheme
1 is involved in the fac–mer isomerization. Therefore, we
proposed the isomerization mechanism shown in Scheme
2, though the intermediates have not been observed.
O
C
+
+
O
C
O
C
Lewis
acid
O
O
O
C
N
N
C
N
N
N
N
C
Mo
Mo
P
Mo
C
N
C
P
N
O
O
P
N
C
O
N
OR
N
N
2.4. Reaction of cis-Mo(CO)4 L2 with TMSOTf
mer
fac
fac
In addition to the isomerization of fac-Mo(CO)3-
{P(OR)3}3 promoted by TMSOTf, the isomerization of
cis-Mo(CO)4{P(OR)3}2 was also investigated. The results
were shown in Table 3. The cis–trans isomerization
occurred in the presence of TMSOTf and did not in the
absence of TMSOTf for cis-5, and cis-6, and TMSOTf
worked as a catalyst. The 31P NMR signals of trans-5
and trans-6 were observed at 173.4 and 155.1 ppm, respec-
tively. In contrast, cis-4 did not isomerize to trans-4 even in
the presence of TMSOTf. For the cis–trans isomerization,
the reaction pathway similar to that for the fac–mer isom-
erization of Mo(CO)3{P(OR)3}3 shown in Scheme 2 is pro-
posed. Interaction of TMS+ with an oxygen in the P(OR)3
ligands may initiate the cis–trans isomerization. The basi-
city of the phosphite oxygen in cis-Mo(CO)4{P(OR)3}2 is
considered to be less than that in fac-Mo(CO)3{P(OR)3}3
because the former complex has more CO ligands in num-
ber being a strong p-accepter ligand. Among cis-4, cis-5,
and cis-6, cis-4 has least oxygen basicity because of the sub-
ð4Þ
The other isomerization mechanism is shown in Scheme 2.
The silicon atom in TMS+ interacts with one oxygen in
P(OR)3 ligands to form fac00, but does not abstract the
OR group as an anion. The interaction weakens the coor-
dination of the P(OR)3(TMS) ligand toward the central
metal and makes the ligand bulky, thereby decreasing the
isomerization energy barrier to give its mer isomer (mer00).
Dissociation of TMS+ from mer00 gives mer-Mo(CO)3-
{P(OR)3}3 with regeneration of TMSOTf. The similar
isomerization mechanism has been proposed for the isom-
erization of Mo(CO)3{P(OR)3}3 promoted by Me3SiX
(X = Cl, Br, I) [27].
There is a possibility that dissociation of one of the
phosphites in Mo(CO)3{P(OR)3}3 induces the isomeriza-
tion and TMSOTf promotes the dissociation. To check
the possibility, a crossover experiment was conducted.

1972
K. Fukumoto, H. Nakazawa / Journal of Organometallic Chemistry 693 (2008) 1968–1974
Table 3
Therefore, it was found in the reaction of cis-5 with
BF3 ꢀ OEt2, relatively fast OMe/F substitution reaction
and relatively slow cis to trans isomerization and some
unidentified reactions take place.
Isomerization of Mo(CO)4{P(OR)3}2 by TMSOTf in CH2Cl2 at room
temperature
P(OR)3
P(OR)3
O
O
O
O
C
TMSOTf a
C
C
C
3. Experimental
Mo
Mo
C
C
C
P(OR)3
O
O
O
3.1. General remarks
C
O
P(OR)3
All reactions were carried out under an atmosphere of
dry nitrogen by using Schlenk tube techniques. CH2Cl2
was distilled from CaH2, and hexane and THF were dis-
tilled from sodium metal. These were stored under nitrogen
atmosphere. Mo(CO)3(NCMe)3 [30] and Mo(CO)4(nbd)
[31] were prepared according to the literature methods.
Fac-Mo(CO)3(L)3 and cis-Mo(CO)4(L)2 (L = phosphite)
were prepared by the modification of the published proce-
dures [28,29]. IR spectra were recorded on a Perkin–Elmer
Spectrum One spectrometer. A JEOL JNM-AL400 spec-
P(OR)3
P(OPh)3
P(OMe)3
PPh2(OMe)
a
cis:transb
cis-4
cis-5
cis-6
trans-4
trans-5
trans-6
no reaction
1:0.9
1:2.3
1.0, 0.5 and 0.1 equvalents based on the cis complex were used.
cis:trans equilibrium ratio after completion of the isomerization.
b
stituents (Ph vs. Me). Therefore, cis-4 may not have enough
basicity on the oxygen to form an interaction with TMS+.
trometer was used to obtain H, 13C, and 31P NMR spec-
1
1
tra. H and 13C NMR data were referenced to Me4Si. 31P
2.5. Reaction of fac-Mo(CO)3L3 and cis-Mo(CO)4L2 with
BF3 ꢀ OEt2
NMR data were referenced to 85% H3PO4.
3.2. Preparation of fac-Mo(CO)3{P(OPh)3}3 (fac-1)
TMSOTf and BF3 ꢀ OEt2 are effective Lewis acids to
obtain a cationic phosphenium complex by an OR anion
abstraction from a diamino-substituted phosphite ligand
in a transition metal complex. In contrast, TMSOTf does
not abstract an OR anion from a P(OR)3 ligand of
fac-Mo(CO)3{P(OR)3}3 and cis-Mo(CO)4{P(OR)3}2, but
promotes the fac–mer and cis–trans isomerization. There-
fore, reactions of fac-Mo(CO)3{P(OMe)3}3 (fac-2) and
cis-Mo(CO)4{P(OMe)3}2 (cis-5) with BF3 ꢀ OEt2 were
examined and it was found that BF3 ꢀ OEt2 causes some
complicated reactions in addition to isomerization.
The 31P NMR spectrum of the reaction mixture of fac-2
and an equimolar amount of BF3 ꢀ OEt2 in CH2Cl2 showed
several unidentified signals in addition to signals assignable
to mer-2. These signals increased in intensity with time but
the singlet due to the starting complex (fac-2) still remained
after several hours.
A THF solution (20 mL) containing Mo(CO)3(NCMe)3
(0.52 g, 1.72 mmol) and P(OPh)3 (1.36 mL, 5.19 mmol) was
stirred for 4 h at room temperature. After volatile materials
were removed under reduced pressure, the resulting precip-
itate was washed with hexane a few times and dried in
vacuo to give a white powder of fac-1 (1.57 g, 1.41 mmol,
82%). 1H NMR (d, in CDCl3): 6.98–7.18 (m, Ph).
13C{1H} NMR (d, in CDCl3): 121.9 (s, p-Ph), 124.3 (s,
m-Ph), 129.4 (s, o-Ph), 152.1 (s, ipso-Ph), 212.2 (m, CO).
31P{1H} NMR (d, in CDCl3): 145.0 (s). IR (cmꢁ1, in
CHCl3): m (CO) 1917, 1992.
3.3. Preparation of fac-Mo(CO)3{P(OMe)3}3 (fac-2)
A THF solution (20 mL) containing Mo(CO)3(NCMe)3
(0.55 g, 1.81 mmol) and P(OMe)3 (0.65 mL, 5.51 mmol)
was stirred for 4 h at room temperature. After volatile
materials were removed under reduced pressure, the
resulting precipitate was washed with hexane a few times
and dried in vacuo to give a white powder of fac-2
The reaction of cis-5 with an equimolar amount of
BF3 ꢀ OEt2 in CH2Cl2 at room temperature was followed
by the 31P NMR measurement. After 4 h, in addition to
a strong singlet due to cis-5, a doublet of doublet at
1
2
1
164.5 ppm (d, JPF = 1157.1, and JPP = 46.9 Hz) and a
(0.92 g, 1.67 mmol, 92%). H NMR (d, in CDCl3): 3.61
2
3
doublet at 163.4 ppm (d, JPP = 46.9 Hz) were observed.
(d, JPH = 10.8 Hz, OCH3). 13C{1H} NMR (d, in CDCl3):
The large coupling constant (1157.1 Hz) suggests the exis-
tence of a P–F bond and the small coupling constant
(46.9 Hz) indicates that two phosphorus ligands are cis to
each other. Therefore, the formation of cis-Mo(CO)4{P(O-
Me)3}{P(OMe)2F} was proposed. The similar OR/F sub-
stitution reaction has been reported [6,9,11]. The 31P
NMR spectrum after 24 h, signals due to cis-Mo(CO)4-
{P(OMe)3}{P(OMe)2F} increased in intensity and a new
singlet at 173.4 ppm attributable to trans-5 was observed.
In addition, several unidentified signals were observed.
51.4 (m, OCH3), 215.9 (m, CO). 31P{1H} NMR (d, in
CDCl3): 168.0 (s). IR (cmꢁ1, in CDCl3): m (CO) 1880, 1967.
3.4. Preparation of fac-Mo(CO)3{P(OEt)3}3 (fac-3)
A THF solution (20 mL) containing Mo(CO)3(NCMe)3
(0.39 g, 1.30 mmol) and P(OEt)3 (0.67 mL, 3.90 mmol) was
stirred for 4 h at room temperature. After volatile materials
were removed under reduced pressure, the resulting precip-
itate was washed with hexane a few times at ꢁ78 °C and

K. Fukumoto, H. Nakazawa / Journal of Organometallic Chemistry 693 (2008) 1968–1974
1973
dried in vacuo to give a white powder of fac-3 (0.61 g,
1.2 mmol, 92%). 1H NMR (d, in CDCl3): 1.22 (m, 3H,
OCH2CH3), 3.96 (m, 2H, OCH2CH3). 13C{1H} NMR (d,
in CDCl3): 16.4 (m, OCH2CH3), 59.7 (s, OCH2CH3),
216.4 (m, CO). 31P{1H} NMR (d, in CDCl3): 161.2 (s).
IR (cmꢁ1, in CHCl3): m (CO) 1860, 1963.
1.5 h at room temperature. After volatile materials were
removed under reduced pressure, the resulting precipitate
was washed with hexane (3 mL, 5 times) at ꢁ78 °C and
dried in vacuo to give a white powder of a mixture of
fac-1 and mer-1 (1:30). To obtain pure mer-1, the powder
was washed with hexane/CH2Cl2 = 100/1 solution (5 mL,
20 times) at room temperature, and the powder was dried
in vacuo (1.22 g, 1.10 mmol, 53%). 1H NMR (d, in CDCl3):
6.83–7.25 (m, Ph). 13C{1H} NMR (d, in CDCl3): 121.6 (s,
p-Ph), 124.2 (s, m-Ph), 129.4 (s, o-Ph), 151.9 (s, ipso-Ph),
208.0 (m, CO), 213.0 (m, CO). 31P{1H} NMR (d, in
3.5. Preparation of cis-Mo(CO)4{P(OPh)3}2 (cis-4)
A CH2Cl2 solution (10 mL) containing Mo(CO)4(nbd)
(0.81 g, 2.46 mmol) and P(OPh)3 (0.83 mL, 4.92 mmol)
was stirred for 4 h at room temperature. After volatile mate-
rials were removed under reduced pressure, the resulting
precipitate was washed with hexane a few times at ꢁ78 °C
and dried in vacuo to give a white powder of cis-4 (1.87 g,
2
CDCl3): 148.6 (t, JPP = 46.9 Hz, equatorial-P), 155.4 (d,
2JPP = 46.9 Hz, apical-P). IR (cmꢁ1, in CHCl3): m (CO)
1931, 1813.
1
2.68 mmol, 92%). H NMR (d , in CDCl3): 7.18–7.36 (m,
3.9. X-ray crystal structure determination of mer-1
Ph). 13C{1H} NMR (d, in CDCl3): 121.6 (s, p-Ph), 124.9
2
(s, m-Ph), 129.8 (s, o-Ph), 151.4 (t, JPC = 4.2 Hz, ipso-
Crystals of mer-1 suitable for an X-ray diffraction study
were obtained through crystallization from CH2Cl2/hex-
ane/benzene for a few days. The single crystal was mounted
in a glass capillary. Data for mer-1 were collected at
ꢁ70 °C on Rigaku/MSC Mercury CCD area-detector dif-
fractometer equipped with monochromated Mo Ka radia-
tion. Calculations for mer-1 were performed with the
teXsan crystallographic software package of Molecular
Structure Corporation. H atoms were refined using a riding
2
2
Ph), 205.5 (t, JPC = 13.3 Hz, cis-CO), 209.5 (t, JPC
=
17.4 Hz, trans-CO). 31P{1H} NMR (d, in CDCl3): 151.4
(s). IR (cmꢁ1, in CHCl3): m (CO) 1940, 2046.
3.6. Preparation of cis-Mo(CO)4{P(OMe)3}2 (cis-5)
A CH2Cl2 solution (10 mL) containing Mo(CO)4(nbd)
(0.73 g, 2.21 mmol) and P(OMe)3 (0.52 mL, 4.42 mmol)
was stirred for 4 h at room temperature. After volatile
materials were removed under reduced pressure, the result-
ing precipitate was washed with hexane a few times at
ꢁ78 °C and dried in vacuo to give a orange sticky powder
˚
model, with C–H = 0.95 A, and fixed individual displace-
ment parameters [Uiso (H) = Ueq(C)]. The crystal was for-
mulated as mer-1 ꢀ 0.5CH2Cl2 ꢀ 0.5C6H6. The CH2Cl2
molecule was disordered in two positions with 50:50 prob-
ability in the unit cell.
1
of cis-5 (0.97 g, 2.13 mmol, 96%). H NMR (d, in CDCl3):
3.62 (s, OCH3). 13C{1H} NMR (d, in CDCl3): 51.4 (s,
2
OCH3), 207.9 (t, JPC = 14.1 Hz, cis-CO), 212.1 (t,
Acknowledgements
2JPC = 13.3 Hz, trans-CO). 31P{1H} NMR (d, in CDCl3):
165.6 (s). IR (cmꢁ1, in CHCl3): m (CO) 2036, 1921.
This work was supported by a Grant-in-Aid for Science
Research on Priority Area (No. 18033044, Chemistry of
Coordination Space, and No. 19027047, Synergistic Effect
of Elements) from the Ministry of Education, Culture,
Sports, Science and Technology.
3.7. Preparation of cis-Mo(CO)4{PPh2(OMe)}2 (cis-6)
A CH2Cl2 solution (10 mL) containing Mo(CO)4(nbd)
(0.63 g, 1.91 mmol) and PPh2(OMe) (0.76 mL, 3.82 mmol)
was stirred for 3 h at room temperature. After volatile
materials were removed under reduced pressure, the result-
ing precipitate was washed with hexane a few times at
ꢁ78 °C and dried in vacuo to give a white powder of
Appendix A. Supplementary material
X-ray crystallographic data in CIF format for mer-1.
This material is available free of charge via the Internet
at http://pubs.acs.org. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2008.02.024.
1
cis-6 (1.17 g, 1.82 mmol, 96%). H NMR (d, in CDCl3):
3.27 (s, 3 H, OCH3), 7.40–7.53 (m, 10H, Ph). 13C{1H}
NMR (d, in CDCl3): 53.6 (s, OCH3), 128.1 (s, p-Ph),
2
130.1 (s, m-Ph), 131.2 (t, JPC = 6.6 Hz, o-Ph), 139.0
2
2
(t, JPC = 15.8 Hz, ipso-Ph), 209.5 (t, JPC = 10.3 Hz,
References
cis-CO), 214.6 (t, JPC = 9.5 Hz, trans-CO). 31P{1H}
2
NMR (d, in CDCl3): 144.9 (s). IR (cmꢁ1, in CHCl3): m
[1] A.H. Cowley, R.A. Kemp, Chem. Rev. 85 (1985) 367.
[2] (a) M. Sanchez, M.R. Mazieres, L. Lamande, R. Wolf, in: M. Regitz,
O.J. Scherer (Eds.), Multiple Bonds and Low Coordination in
Phosphorus Chemistry, Thieme, New York, 1990 (Chapter D1);
(b) A. Schmidpeter, in: M. Regitz, O.J. Scherer (Eds.), Multiple
Bonds and Low Coordination in Phosphorus Chemistry, Thieme,
New York, 1990 (Chapter D2).
(CO) 2026, 1912.
3.8. Isolation of mer-Mo(CO)3{P(OPh)3}3 (mer-1)
A solution of fac-1 (2.31 g, 2.08 mmol) and TMSOTf
(0.38 mL, 2.08 mmol) in CH2Cl2 (20 mL) was stirred for
[3] D. Gudat, Coord. Chem. Rev. 163 (1997) 71.

1974
K. Fukumoto, H. Nakazawa / Journal of Organometallic Chemistry 693 (2008) 1968–1974
[4] H. Nakazawa, J. Organomet. Chem. 611 (2000) 349.
[5] H. Nakazawa, Adv. Organomet. Chem. 50 (2004) 107.
[6] H. Nakazawa, M. Ohta, K. Miyoshi, H. Yoneda, Organometallics 8
(1989) 638.
[18] H. Nakazawa, Y. Yamaguchi, T. Mizuta, S. Ichimura, K. Miyoshi,
Organometallics 14 (1995) 4635.
[19] H. Nakazawa, Y. Yamaguchi, K. Miyoshi, Organometallics 15
(1996) 1337.
[7] H. Nakazawa, Y. Yamaguchi, K. Miyoshi, J. Organomet. Chem. 465
(1994) 193.
[20] H. Nakazawa, Y. Yamaguchi, K. Kawamura, K. Miyoshi, Organo-
metallics 16 (1997) 4626.
[8] H. Nakazawa, Y. Yamaguchi, T. Mizuta, K. Miyoshi, Organome-
tallics 14 (1995) 4137.
[21] K. Kawamura, H. Nakazawa, K. Miyoshi, Organometallics 18
(1999) 1517.
[9] Y. Yamaguchi, H. Nakazawa, T. Itoh, K. Miyoshi, Bull. Chem. Soc.
Jpn. 69 (1996) 983.
[22] K. Kawamura, H. Nakazawa, K. Miyoshi, Organometallics 18
(1999) 4785.
[10] H. Nakazawa, Y. Yamaguchi, K. Miyoshi, Phosphorus Sulfur Silicon
Relat. Elem. 109 (1996) 129.
[11] H. Nakazawa, Y. Yamaguchi, K. Miyoshi, A. Nagasawa, Organo-
metallics 15 (1996) 2517.
[23] H. Nakazawa, M. Kishishita, T. Nakamoto, N. Makanura, T.
Ishiyama, K. Miyoshi, Chem. Lett. (2000) 230.
[24] A.M. Bond, R. Colton, S.W. Feldberg, P.J. Mahon, T. Whyte,
Organometallics 10 (1991) 3320.
[12] K. Takano, H. Tsumura, H. Nakazawa, M. Kurakata, T. Hirano,
Organometallics 19 (2000) 3323.
[25] J.-C. Rousche, G.R. Dobson, Inorg. Chim. Acta 28 (1978)
L139.
[13] H. Nakazawa, Y. Miyoshi, T. Katayama, T. Mizuta, K. Miyoshi, N.
Tsuchida, A. Ono, K. Takano, Organometallics 25 (2006) 5913.
[14] H. Nakazawa, M. Kishishita, S. Yoshinaga, Y. Yamaguchi, T.
Mizuta, K. Miyoshi, J. Organomet. Chem. 529 (1997) 423.
[15] H. Nakazawa, M. Kishishita, K. Miyoshi, Phosphorus Sulfur Silicon
Relat. Elem. 144 (1999) 45.
[26] J.A.S. Howell, P.C. Yates, N.F. Ashford, D.T. Dixon, R. Warren, J.
Chem. Soc., Dalton Trans. 20 (1996) 3959.
[27] K. Fukumoto, H. Nakazawa, Organometallics 26 (2007) 6505.
[28] E.C. Alyea, G. Ferguson, S.-Q. Song, Acta Crystallogr. C 51 (1995)
2238.
[29] G.R. Dobson, A.J. Rettenmaier, Inorg. Chim. Acta
6
(1972)
[16] H. Nakazawa, M. Kishishita, T. Ishiyama, T. Mizuta, K. Miyoshi, J.
Organomet. Chem. 617–618 (2001) 453.
[17] H. Nakazawa, Y. Yamashita, K. Miyoshi, Phosphorus Sulfur, Silicon
Relat. Elem. 177 (2002) 1533.
507.
[30] D.P. Tate, W.R. Knipple, J.M. Augl, Inorg. Chem.
433.
[31] M.A. Bennett, L. Pratt, G. Wilkinson, J. Chem. Soc. (1961) 2037.
1
(1962)