Reaction of [M(η3-allyl)(η2-amidinato)(CO) 2(pyridine)] complexes (M = Mo, W) with bidentate ligands: Nitrogen donor vs. phosphorus donor

Article abstract of DOI:10.1039/b410927a

The reactivity of amidinato complexes of molybdenum and tungsten bearing pyridine as a labile ligand, [M(η³-allyl)(η²- amidinato)(CO)₂(pyridine)] (M = Mo; 1-Mo, M = W; 1-W), toward bidentate ligands such as 1,10-phenanthroline (phen) and 1,2- bis(diphenylphosphino)ethane (dppe) was investigated. The reaction of 1 with phen at ambient temperature resulted in the formation of monodentate amidinato complexes, [M(η³-allyl)(η¹-amidinato)(CO) ₂(η²-phen)] (M = Mo; 2-Mo, M = W; 2-W), which has pseudo-octahedral geometry with the amidinato ligand coordinated to the metal in an η¹-fashion. The phen ligand was located coplanar with two CO ligands and the η¹-amidinato ligand was positioned trans to the η³-allyl ligand. In solution, both complexes 2-Mo and 2-W showed fluxionality, and complex 2-Mo afforded allylamidine (3) on heating in solution. In the reaction of 1 with dppe at ambient temperature, the simple substitution reaction took place to give dppe-bridged binuclear complexes [{M{η³-allyl)(η²-amidinato)(CO)₂} ₂(μ-dppe)] (M = Mo; 5-Mo, M = W; 5-W), whereas mononuclear monocarbonyl complexes [M(η³-allyl)(η²-amidinato) (CO)(η²-dppe)] (M = Mo; 6-Mo, M = W; 6-W) were obtained under acetonitrile- or toluene-refluxing conditions. Mononuclear complex 6 was also obtained by the reaction of binuclear complex 5 with 0.5 equivalents of dppe under refluxing in acetonitrile or in toluene. The X-ray analyses and variable-temperature ³¹P NMR spectroscopy of complex 6 indicated the existence of the rotational isomers of the η³-allyl ligand, i.e., endo and exo forms, with respect to the carbonyl ligand. The different reactivity of complex 1 toward phen and dppe seems to have come from the difference in the π-acceptability of each bidentate ligand.

Full text of DOI:10.1039/b410927a

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F U L L P A P E R
Reaction of [M(g3-allyl)(g2-amidinato)(CO)2(pyridine)] complexes
(M = Mo, W) with bidentate ligands: nitrogen donor vs. phosphorus
donor†
Yoshitaka Yamaguchi,*a Kenichi Ogata,a Kimiko Kobayashib and Takashi Ito*a
a Department of Materials Chemistry, Graduate School of Engineering, Yokohama National
University, 79-5, Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
b The Institute of Physical and Chemical Research (RIKEN), Hirosawa, Wako, Saitama,
351-0198, Japan
Received 16th July 2004, Accepted 20th October 2004
First published as an Advance Article on the web 29th October 2004
The reactivity of amidinato complexes of molybdenum and tungsten bearing pyridine as a labile ligand,
3
2
[M(g -allyl)(g -amidinato)(CO)2(pyridine)] (M = Mo; 1-Mo, M = W; 1-W), toward bidentate ligands such as
1,10-phenanthroline (phen) and 1,2-bis(diphenylphosphino)ethane (dppe) was investigated. The reaction of 1 with
phen at ambient temperature resulted in the formation of monodentate amidinato complexes,
3
1
2
[M(g -allyl)(g -amidinato)(CO)2(g -phen)] (M = Mo; 2-Mo, M = W; 2-W), which has pseudo-octahedral geometry
1
with the amidinato ligand coordinated to the metal in an g -fashion. The phen ligand was located coplanar with two
1
3
CO ligands and the g -amidinato ligand was positioned trans to the g -allyl ligand. In solution, both complexes 2-Mo
and 2-W showed fluxionality, and complex 2-Mo afforded allylamidine (3) on heating in solution. In the reaction of 1
with dppe at ambient temperature, the simple substitution reaction took place to give dppe-bridged binuclear
3
2
complexes [{M(g -allyl)(g -amidinato)(CO)2}2(l-dppe)] (M = Mo; 5-Mo, M = W; 5-W), whereas mononuclear
3
2
2
monocarbonyl complexes [M(g -allyl)(g -amidinato)(CO)(g -dppe)] (M = Mo; 6-Mo, M = W; 6-W) were obtained
under acetonitrile- or toluene-refluxing conditions. Mononuclear complex 6 was also obtained by the reaction of
binuclear complex 5 with 0.5 equivalents of dppe under refluxing in acetonitrile or in toluene. The X-ray analyses and
variable-temperature 31P NMR spectroscopy of complex 6 indicated the existence of the rotational isomers of the
3
g -allyl ligand, i.e., endo and exo forms, with respect to the carbonyl ligand. The different reactivity of complex 1
toward phen and dppe seems to have come from the difference in the p-acceptability of each bidentate ligand.
coordinatively unsaturated species formed by dissociation of
Introduction
the pyridine ligand as depicted in Scheme 1.6 The first one
3
g -Allyldicarbonyl complexes of molybdenum and tungsten
3
accompanies the hapticity change of the allyl ligand from the g -
often play an important role in both coordination chemistry1 and
1
to the g -mode, whose dynamic behavior has been demonstrated
catalytic organic transformations.2 A series of allyl complexes
using nucleophilic solvent as a Lewis base (Path A).9 The second
3
of Mo and W have been prepared by the reaction of [M(g -
one contains the insertion of one of the CO ligands into metal–
allyl)X(CO)2(NCMe)2] (M = Mo, W; X = Cl, Br),3 which is a
amidinato nitrogen bond to give a carbamoyl-type complex
good precursor for a coordinatively unsaturated reactive inter-
mediate due to possessing two labile acetonitrile and one halide
ligands, with four-electron donating neutral ligands4 as well as
anionic ligands.5 Although an amidinato ligand, which acts as
an anionic four-electron donor, has been known to be one of
the most important heteroallylic ligands capable of controlling
the stability and/or reactivity of metal complexes because of
its ability to act as both chelating and bridging modes toward
metals as reviewed by Kilner6 and Edelmann,7 there has been no
investigation on this respect. We have started our research on the
amidinato complexes of Mo and W, and have recently reported
the preparation and some reactivity of amidinato complexes
3
2
formulated as [M(g -allyl)(g -amidinato)(CO)2(pyridine)] (M =
8a
Mo; 1-Mo, M = W; 1-W).
The complex 1 has one labile pyridine ligand, which is
easily substituted by two-electron donor such as PR3 to afford
the corresponding phosphine-coordinated complex.8 In our
further studies on the reactivity of 1, we were interested in
its reaction with bidentate four-electron donor such as 1,10-
phenanthroline (phen) and 1,2-bis(diphenylphosphino)ethane
(dppe). Four possible reaction sites would be expected in the
† Electronic supplementary information (ESI) available: ORTEP
drawings of complexes 2, 5 and 6 with the atom-numbering scheme
and 2D-NMR spectra of complex 6. See http://www.rsc.org/suppdata/
dt/b4/b410927a/
Scheme 1
3 9 8 2
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
©

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1
(Path B).10 The dissociation of CO ligand is the third route (Path
ligands, and the g -amidinato ligand positioned trans to the allyl
ligand. The open face of the allyl ligand was directed toward
two carbonyl ligands, which has been known to be a favorable
2
C). There is also a rare example in which the g -amidinato ligand
1
converts into the g -amidinato ligand (Path D). We investigated
3
the reactions of 1 with phen and dppe, and found differences of
the reactivity of the amidinato complex 1 depending on these
four-electron donor molecules.
orientation for a series of [M(g -allyl)(CO)2] complexes (M =
Mo, W).11 The geometry of these complexes revealed by X-ray
analyses coincides with the results obtained by low-temperature
1H NMR measurements described above.
In the amidinato ligand in complex 2, the N(1)–C(1) bond dis-
Results and discussion
˚
˚
tances (1.353(4) A for 2-Mo and 1.356(5) A for 2-W) are slightly
Reaction of amidinato(pyridine) complexes 1 with phen.
˚
longer than the N(2)–C(1) bond distances (1.296(4) A for 2-Mo
Formation of g1-amidinato complexes
˚
and 1.286(5) A for 2-W). However, these bond distances are
˚
within the mean value of the N–C single bond (1.48 A) and the
On treatment of complex 1-Mo with one equivalent of 1,10-
phenanthroline (phen) in CH2Cl2 at room temperature, an
initial yellow solution instantaneously changed to a red solution
from which red crystals were isolated in 87% yield. In a case
of tungsten complex 1-W, a similar reaction took place to
give red crystals in 85% isolated yield. Elemental analyses,
6
˚
N–C double bond (1.24 A), indicating that the amidinato N–C–
N bond electrons are delocalized even in g -coordination mode.
1
The covalent Mo(1)–N(1) bond distance in 2-Mo is 2.199(3)
A, which is slightly shorter than the dative Mo–N(amidine)
˚
bond distance in the amidinato(amidine) complex of molyb-
3
2
ꢀ
˚
1
denum (2.25(2) A for [Mo(g -allyl){g -(NPh)2CH}(CO)2(N,N -
IR, low-temperature H NMR spectra, and X-ray diffraction
8b
1
diphenylformamidine)]. Similar results have been reported
studies established the formation of g -amidinato complex
in Pt12 and Hg13 complexes bearing g -amidinato or amidine
1
3
1
2
formulated as [M(g -allyl)(g -amidinato)(CO)2(g -phen)] (M =
ligands.
Mo; 2-Mo, M = W; 2-W) (eqn. (1)).
It has been reported that the M–N–Y–N (Y = CH or N) skele-
ton in the related compounds such as amidine,12 amidinato,12,13
or triazenido14 shows the ‘cisoid’ arrangement as a common
feature. It was concluded that the ‘cisoid’ conformation is
electronically favored over the ‘transoid’ one. In this respect,
it is noteworthy that the M–N–C–N skeleton in the complexes
2-Mo and 2-W adopts the ‘transoid’ arrangement. Furthermore,
the ‘transoid’ Mo–N–C–N skeleton was also found in the
(1)
8b
amidinato(amidine) complex of Mo mentioned above. The
In the IR spectra, both complexes showed two CO stretching
bands at 1931 and 1842 cm−1 for 2-Mo, and 1921 and 1828 cm−1
for 2-W. These observations indicate that two carbonyl ligands
adaptation of the ‘transoid’ conformation in our system seems
to have come from the steric reason.
1
Complexes 2-Mo and 2-W in solution showed fluxional
are located in mutually cis positions. The H NMR spectrum
1
behavior as observed by H NMR spectroscopy. As is already
of 2-Mo at ambient temperature showed broad signals, whereas
sharp signals were observed at low temperature (at −40 ◦C).
Allyl protons were observed at 1.47 (anti-CH2), 2.72 (central
proton) and 3.16 (syn-CH2) ppm. Four sets of phenanthroline
protons were detected at 7.65 (s), 7.79 (dd, J = 7.9, 4.6 Hz),
8.32 (dd, J = 7.9, 1.3 Hz), and 9.12 (dd, J = 4.6, 1.3 Hz) ppm
with each of 2H integration. Similar spectroscopic data were
mentioned above, the low-temperature 1H NMR spectrum
suggested that the presence of a mirror plane consisting of the
central allyl carbon, metal, and the amidinato nitrogen which
is in agreement with the X-ray analyses. We next investigated
the fluxional behavior of complexes 2-Mo and 2-W at higher
temperatures, which was monitored by 1H NMR in DMSO-d6.
In the case of molybdenum complex 2-Mo, the broad signals
observed at room temperature did not change up to about
65 ◦C. On further raising the temperature the sharp signals
being assignable to the new product appeared at 70 ◦C. In order
to characterize the product, we examined this thermal reaction
in a Schlenk tube and a pale yellow waxy solid was isolated
from the reaction mixture. The characterization of the waxy
solid was achieved spectroscopically to indicate the formation
of allylamidine 3 in 53% yield (eqn. (2)). It is conceivable
that the formation path of the allylamidine 3 from 2-Mo is
via intramolecular reductive elimination between the allyl and
amidinato ligands. Recently, Pe´rez and co-workers have reported
systematic studies on the reductive elimination of molybde-
num complexes from a viewpoint of the Mo-catalyzed allylic
alkylation.15 Their results demonstrated that allylic alkylation
(C–C bond formation) occurs via reductive elimination when
the allyl and nucleophilic groups are in mutually cis positions. In
1
obtained by low-temperature H NMR measurement of 2-W.
These observations suggest the geometry of 2 possessing a mirror
plane through the central carbon of the allyl group, M (Mo or
W), and the coordinated nitrogen atom of the amidinato ligand.
1
In order to confirm g -coordination mode of the amidinato
ligand in complex 2, X-ray diffraction analyses of complexes
2-Mo and 2-W were undertaken.
The ORTEP drawing of complex 2-Mo is displayed in Fig. 1.
Complex 2-W showed similar structural features as 2-Mo. The
crystal data and selected bond distances and angles are listed
in Tables 1–3, respectively. Complexes 2-Mo and 2-W have
pseudo-octahedral geometry around the central metal, and have
1
amidinato ligand coordinated to the metal with g -coordination
mode. The phen ligand was located coplanar with two CO
1
the complex 2-Mo, the allyl and g -amidinato ligands are found
to be located in mutually trans positions in the solid state and in
solution at low-temperature. The formation of an allylamidine at
higher temperature suggests that the allyl and amidinato ligands
can adopt mutually cis positions (cis-2 in eqn. (2)) by a fluxional
process.
Fig. 1 ORTEP drawing of 2-Mo with thermal ellipsoids drawn at the
50% probability level. Hydrogen atoms except for H1 are omitted for
clarity.
(2)
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0
3 9 8 3

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3 9 8 4
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0

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◦
˚
Table 2 Selected bond distances (A) and angles ( ) for molybdenum complexes 2-Mo, 5-Mo and 6-Mo
2-Mo
5-Mo
6-Mo
CO
Mo(1)–C(14)
Mo(1)–C(15)
O(1)–C(14)
O(2)–C(15)
1.960(4)
1.966(4)
1.158(4)
1.156(4)
Mo(1)–C(14)
Mo(1)–C(15)
O(1)–C(14)
O(2)–C(15)
1.968(3)
1.951(3)
1.159(4)
1.164(4)
Mo(1)–C(14)
O(1)–C(14)
1.898(3)
1.180(3)
Amidinato
Mo(1)–N(1)
N(1)–C(1)
N(2)–C(1)
2.199(3)
1.353(4)
1.296(4)
Mo(1)–N(1)
Mo(1)–N(2)
N(1)–C(1)
N(2)–C(1)
2.229(2)
2.272(2)
1.332(3)
1.325(3)
Mo(1)–N(1)
Mo(1)–N(2)
N(1)–C(1)
N(2)–C(1)
2.210(2)
2.362(2)
1.334(3)
1.312(3)
Others around M
CO
Mo(1)–N(3)
Mo(1)–N(4)
2.242(3)
2.252(3)
Mo(1)–P(1)
2.5677(7)
Mo(1)–P(1)
Mo(1)–P(2)
2.5460(8)
2.4427(6)
Mo(1)–C(14)–O(1)
Mo(1)–C(15)–O(2)
177.3(3)
177.1(3)
Mo(1)–C(14)–O(1)
Mo(1)–C(15)–O(2)
176.8(3)
177.5(3)
Mo(1)–C(14)–O(1)
176.7(2)
Amidinato
Mo(1)–N(1)–C(1)
Mo(1)–N(1)–C(2)
C(1)–N(1)–C(2)
N(1)–C(1)–N(2)
C(1)–N(2)–C(8)
121.1(2)
123.3(2)
114.8(3)
126.6(3)
116.5(3)
Mo(1)–N(1)–C(1)
Mo(1)–N(1)–C(2)
C(1)–N(1)–C(2)
Mo(1)–N(2)–C(1)
Mo(1)–N(2)–C(8)
C(1)–N(2)–C(8)
N(1)–C(1)–N(2)
95.3(2)
139.9(2)
123.9(2)
93.6(2)
143.1(2)
123.1(2)
112.3(2)
Mo(1)–N(1)–C(1)
Mo(1)–N(1)–C(2)
C(1)–N(1)–C(2)
Mo(1)–N(2)–C(1)
Mo(1)–N(2)–C(8)
C(1)–N(2)–C(8)
N(1)–C(1)–N(2)
97.1(2)
139.8(2)
122.8(2)
90.8(2)
149.0(2)
120.2(2)
114.1(2)
Others around M
N(3)–Mo(1)–N(4)
N(3)–Mo(1)–C(15)
C(14)–Mo(1)–C(15)
C(14)–Mo(1)–N(4)
73.34(10)
99.4(1)
81.3(1)
N(1)–Mo(1)–N(2)
N(1)–Mo(1)–C(15)
C(14)–Mo(1)–C(15)
C(14)–Mo(1)–N(2)
58.69(8)
106.5(1)
79.6(1)
N(1)–Mo(1)–N(2)
N(1)–Mo(1)–C(14)
P(2)–Mo(1)–C(14)
P(2)–Mo(1)–N(2)
N(1)–Mo(1)–P(2)
N(2)–Mo(1)–C(14)
57.97(7)
105.86(9)
81.65(8)
113.74(5)
154.39(6)
163.71(9)
104.6(1)
113.9(1)
◦
˚
Table 3 Selected bond distances (A) and angles ( ) for tungsten complexes 2-W, 5-W and 6-W
2-W
5-W
6-W
CO
W(1)–C(14)
W(1)–C(15)
O(1)–C(14)
O(2)–C(15)
1.956(4)
1.958(4)
1.167(5)
1.161(5)
W(1)–C(14)
W(1)–C(15)
O(1)–C(14)
O(2)–C(15)
1.958(4)
1.968(4)
1.157(5)
1.162(5)
W(1)–C(14)
O(1)–C(14)
1.901(4)
1.188(4)
Amidinato
W(1)–N(1)
N(1)–C(1)
N(2)–C(1)
2.173(3)
1.356(5)
1.286(5)
W(1)–N(1)
W(1)–N(2)
N(1)–C(1)
N(2)–C(1)
2.263(3)
2.227(3)
1.324(4)
1.332(4)
W(1)–N(1)
W(1)–N(2)
N(1)–C(1)
N(2)–C(1)
2.202(3)
2.342(3)
1.333(5)
1.312(4)
Others around M
CO
W(1)–N(3)
W(1)–N(4)
2.257(3)
2.238(3)
W(1)–P(1)
2.5586(8)
W(1)–P(1)
W(1)–P(2)
2.538(1)
2.4381(8)
W(1)–C(14)–O(1)
W(1)–C(15)–O(2)
178.6(4)
176.5(4)
W(1)–C(14)–O(1)
W(1)–C(15)–O(2)
177.6(3)
177.5(4)
W(1)–C(14)–O(1)
176.7(3)
Amidinato
W(1)–N(1)–C(1)
W(1)–N(1)–C(2)
C(1)–N(1)–C(2)
N(1)–C(1)–N(2)
C(1)–N(2)–C(8)
119.9(3)
124.5(3)
114.7(3)
126.8(4)
116.7(4)
W(1)–N(1)–C(1)
W(1)–N(1)–C(2)
C(1)–N(1)–C(2)
W(1)–N(2)–C(1)
W(1)–N(2)–C(8)
C(1)–N(2)–C(8)
N(1)–C(1)–N(2)
94.0(2)
142.6(2)
123.2(3)
95.4(2)
139.3(2)
124.6(3)
111.9(3)
W(1)–N(1)–C(1)
W(1)–N(1)–C(2)
C(1)–N(1)–C(2)
W(1)–N(2)–C(1)
W(1)–N(2)–C(8)
C(1)–N(2)–C(8)
N(1)–C(1)–N(2)
97.4(2)
139.3(2)
123.0(3)
91.7(2)
147.9(2)
120.5(3)
112.9(3)
Others around M
N(3)–W(1)–N(4)
N(3)–W(1)–C(15)
C(14)–W(1)–C(15)
C(14)–W(1)–N(4)
73.2(1)
104.3(1)
80.3(2)
N(1)–W(1)–N(2)
N(1)–W(1)–C(15)
C(14)–W(1)–C(15)
C(14)–W(1)–N(2)
58.7(1)
114.2(1)
79.5(2)
N(1)–W(1)–N(2)
N(1)–W(1)–C(14)
P(2)–W(1)–C(14)
P(2)–W(1)–N(2)
N(1)–W(1)–P(2)
N(2)–W(1)–C(14)
57.9(1)
105.5(1)
81.7(1)
114.08(8)
154.37(8)
163.3(1)
101.2(2)
106.3(1)
3
It is reported that 16-electron square-planer late-transition
metal complexes bearing the ‘cisoid’ g -amidinato or triazenido
generally accepted for a series of g -allyldicarbonyl complexes
of molybdenum and tungsten,16 seems to be conceivable for the
explanation of the fluxional process.17 In a case of tungsten
complex 2-W, on the other hand, no transformation of the
complex was observed up to 85 ◦C in DMSO-d6.
1
ligand often show fluxional behavior. The most likely process
in these complexes involves the intermediacy of a chelated
N,Nꢀ-bonded amidinato or triazenido ligand.12,14 In our system,
which are of coordinatively saturated metal complexes involving
The reaction of 1-Mo with 2,2ꢀ-bipyridine (bpy) occurred
instantly to form a red solution. After work-up, a red powder
1
‘transoid’ g -amidinato ligand, the twisted mechanism, which is
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0
3 9 8 5

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was obtained and was analyzed by IR spectroscopy. The CO
stretching bands were observed at 1928 and 1840 cm−1, which
are similar to those for the phen complex 2-Mo (1931 and
1842 cm−1), indicating the product being a bpy complex having
1
an g -amidinato ligand (4), as is supported by elemental analysis
(eqn. (3)). Furthermore, heating 1-Mo in pyridine did not afford
1
a monodentate bis(pyridine) complex containing g -amidinato
ligand and the complex 1-Mo remained intact. These results
indicate that the bidentate nitrogen ligands such as phen and
1
bpy play an important role to produce g -amidinato complexes.
(3)
Reaction of amidinato(pyridine) complexes 1 with dppe.
Formation of l-dppe binuclear and g2-dppe mononuclear
complexes
In the reaction of 1 with bidentate nitrogen compounds
such as phen and bpy, it was found that the fourth reac-
tion pattern (Path D) depicted in Scheme 1 proceeds and
Fig. 2 ORTEP drawing of 5-Mo with thermal ellipsoids drawn at the
50% probability level. Hydrogen atoms except for H1 (and H1*) are
omitted for clarity.
1
that the g -amidinato complex is formed. We next examined
3
2
mononuclear complexes [M(g -allyl)(g -amidinato)(CO)2PEt3]
(M = Mo, W).8 Other geometrical features around the central
metal are also similar to those for the mononuclear complexes
bearing the PEt3 ligand. Furthermore, the bond distances and
angles in 5-Mo have a close similarity to those of tungsten
complex 5-W.
the reaction of 1 with the bidentate phosphorus ligand,
1,2-bis(diphenylphosphino)ethane (dppe). Upon treatment of
molybdenum complex 1-Mo with dppe in CH2Cl2 at ambient
temperature, a homogeneous yellow solution gradually turned
to a heterogeneous system and afforded an orange precipitate
(5-Mo, 60% isolated yield). A similar feature was observed with
tungsten complex 1-W, i.e., an orange precipitate was formed
(5-W, 60% isolated yield) (eqn. (4)).
When the reactions between 1 and dppe were performed
under refluxing conditions in acetonitrile for molybdenum or in
toluene for tungsten, the mononuclear complexes formulated as
3
2
2
[M(g -allyl)(g -amidinato)(CO)(g -dppe)] (M = Mo; 6-Mo, M =
W; 6-W) were formed (eqn. (5)). The reaction of 1-Mo with
one equivalent of dppe in acetonitrile under reflux resulted
3
2
in a homogeneous red solution, from which [Mo(g -allyl)(g -
2
amidinato)(CO)(g -dppe)] (6-Mo) was isolated in 59% yield.
The similar reaction with tungsten complex 1-W afforded
mononuclear complex 6-W with concomitant formation of
binuclear complex 5-W. Complex 6-W was obtained as a single
component under toluene-refluxing conditions and isolated in
50% yield.
(4)
In the IR spectra, two CO stretching bands at 1924 and
1843 cm−1 for 5-Mo and at 1916 and 1831 cm−1 for 5-W were
observed, whose stretching bands were slightly higher than
8b
8a
those for PEt3 complexes of Mo and W, respectively. These
observations indicate that the simple substitution reaction of the
pyridine ligand by dppe occurred and that two carbonyl ligands
were located in mutually cis positions. Complex 5 was so poorly
soluble toward various organic solvents that the spectroscopic
data could not be obtained satisfactorily. The X-ray analyses
of these complexes revealed the formation of dppe-bridged bin-
(5)
The reaction of binuclear 5-Mo with dppe under acetonitrile-
refluxing conditions afforded complex 6-Mo in 73% isolated
yield, suggesting the stepwise reaction path in the reaction of 1
with dppe; binuclear complex 5 forms at the first stage and then
converts to mononuclear complex 6. The reaction of 5-W with
dppe under toluene-refluxing conditions also afforded complex
6-W in 56% isolated yield.
X-Ray diffraction studies of complexes 6-Mo and 6-W were
undertaken. The ORTEP drawing of complex 6-Mo is displayed
in Fig. 3. The crystal data and selected bond distances and angles
are listed in Tables 1–3, respectively.
3
2
uclear complexes, [{M(g -allyl)(g -amidinato)(CO)2}2(l-dppe)]
(M = Mo; 5-Mo, M = W; 5-W).
Single crystals of 5-Mo and 5-W for X-ray analyses were
directly obtained from the reaction mixture in CH2Cl2. The
ORTEP drawing of complex 5-Mo is displayed in Fig. 2. The
crystal data and selected bond distances and angles are listed in
Tables 1–3, respectively.
X-Ray analyses of complexes 5-Mo and 5-W revealed
the dppe-bridged binuclear skeletons, which have pseudo-
octahedral geometry around each metal. The amidinato ligand
is located at an equatorial position and is coplanar with two CO
ligands. The dppe phosphorus is at an axial position trans to the
Complexes 6-Mo and 6-W are pseudo-octahedral mononu-
clear complexes having one CO and g -dppe ligands. The CO
and one phosphorus are coplanar with the amidinato ligand,
and the other phosphorus of dppe and g -allyl ligands are in
2
3
3
g -allyl ligand in both complexes. The metal–phosphorus bond
mutually trans positions.
˚
˚
distances are 2.5677(7) A for 5-Mo and 2.5586(8) A for 5-W,
Compared with a series of dicarbonyl complexes 2 and
5, the metal–carbonyl moiety in complex 6 shows slightly
which are remarkably similar to those in the PEt3 coordinated
3 9 8 6
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0

View Article Online
Chart 1
rotational isomers in solution by variable-temperature 1H NMR
measurements. The variable-temperature 31P NMR data are
summarized in Table 4. Molybdenum complex 6-Mo in CD2Cl2
at room temperature showed two doublets at 57.1 and 85.3 ppm
with a coupling constant of 24.4 Hz and one broad singlet at
59.9 ppm. At higher temperature (90 ◦C), one set of doublets
was observed. The spe◦ctrum measured at below 0 ◦C showed
four doublets. At −50 C, one set of doublets was observed at
58.9 and 86.6 ppm with a coupling constant of 29.0 Hz and the
other was seen at 61.2 and 86.5 ppm with a coupling constant
of 36.6 Hz. The observed 31P chemical shifts and coupling
constants were consistent with the existence of the rotational
Fig. 3 ORTEP drawing of 6-Mo with thermal ellipsoids drawn at the
50% probability level. Hydrogen atoms except for H1 are omitted for
clarity.
3
isomers of the g -allyl ligand as has been reported by Yih for the
dithio–molybdenum complexes bearing dppe ligands, in that the
endo form shows a smaller coupling constant (ca. 26 Hz) than
the exo form (ca. 39 Hz).19 Therefore, we concluded that the
former doublets can be assigned to endo 6-Mo and the latter
to exo 6-Mo. The integration ratio of endo/exo was 0.75/0.25,
which is in good agreement with value obtained by the X-ray
diffraction study for 6-Mo (ratio of 0.75/0.25). In a case of
tungsten complex 6-W, both isomers were observed even at room
temperature. At −50 ◦C, the integration ratio of endo/exo was
0.70/0.30. This result also conformed to the X-ray analysis of
6-W (ratio of 0.65/0.35).
˚
˚
shorter M(1)–C(14) (1.898(3) A for 6-Mo and 1.901(4) A for
˚
6-W) and longer C(14)–O(1) bond distances (1.180(3) A for 6-
Mo and 1.188(4) A for 6-W). These results are in good agreement
˚
with the CO stretching bands in IR spectra. These complexes
6-Mo and 6-W showed one CO stretching band at 1776 and
1766 cm−1, respectively.
The amidinato ligand shows planarity; the sum of angles
around N(1) and N(2) in 6-Mo is 359.7 and 360.0◦, respectively.
The coordination of the phosphorus group of the dppe ligand
located coplanar with the amidinato ligand caused the steric
repulsion between the amidinato NPh group and thus the angles
around the N(2) nitrogen show larger Mo(1)–N(2)–C(8) and
smaller Mo(1)–N(2)–C(1) angles than the corresponding angles
around the N(1) nitrogen. The Mo(1)–N(1) distance (2.210(2) A,
trans to dppe) is slightly shorter than the Mo(1)–N(2) distance
(2.362(2) A, trans to CO). Although the steric repulsion is not
negligible, this structural feature might arise from the greater
trans effect induced by the CO ligand than by the dppe ligand.
A similar feature was observed in the Mo–P bond distances.
The Mo(1)–P(1) distance (2.5460(8) A, trans to allyl), which is
very similar to that in binuclear complex 5-Mo, is slightly longer
Concluding remarks
˚
We investigated the reaction of complex 1 with bidentate ligands
such as phen and dppe as a continuation of our systematic
research on the reactivity of amidinato(pyridine) complexes of
molybdenum and tungsten. In the case of the nitrogen donor,
phen, the vacant site needed for the coordinatively unsaturated
intermediate was provided by the conversion of the amidinato
˚
˚
2
1
ligand from g - to g -coordination. Although it is well known
that the amidinato ligand can coordinate to the metal in various
˚
than the Mo(1)–P(2) distance (2.4427(6) A, trans to amidinato).
Although these values are within the normal range of the Mo–P
dative bond distances (2.40–2.57 A), the difference between
1
fashions, the g -coordination mode of the amidinato ligand
13
characterized by X-ray analysis is rare.12 On the other hand,
18
˚
in the case of the phosphorus donor, dppe, the vacant reaction
site is provided by the CO dissociation form the metal to afford
monocarbonyl complex 6 via dppe-bridged binuclear complex
5. The different reactivity between phen and dppe might have
come from the difference in the p-acceptability of the bidentate
ligands. Phen, which is a weaker p-acceptor ligand than dppe,20
may change the hapticity of the amidinato ligand prior to the
liberation of one of the CO ligands, whereas the phosphorus
ligand has enough p-acceptability to replace the CO ligand.
In these reactions, however, neither CO insertion into the M–
N(amidinato) bond (Path B in Scheme 1) nor hapticity change of
these bond distances also might have resulted from the greater
trans effect induced by the allyl group than by the amidinato
group. The structural features of tungsten complex 6-W were
very similar to those of 6-Mo mentioned above.
It is notable that the allyl groups in complexes 6-Mo and
6-W were disordered. The central carbon of the allyl ligand
appeared at two sites; one is C(42) and the other is C(42b), as
depicted in Fig. 3. Population analyses were undertaken and
the ratio of C(42)/C(42b) was found to be ca. 0.75/0.25 for
6-Mo and 0.65/0.35 for 6-W. In both complexes, the major
rotational isomer is the endo form, which is defined by the open
face of the allyl ligand and the carbonyl ligand being in the
same direction. The minor isomer is exo form, which is the
opposite concerning the allyl and CO ligands (Chart 1). Yih and
3
1
allyl ligand from g - to g -fashion (Path A in Scheme 1) has been
observed. A further investigation of the reactivity of complex 1
on this line is now in progress.
3
co-workers have reported the rotational isomers of the g -allyl
Experimental
group in dithio–molybdenum complexes bearing a bidentate
phosphorus ligand.19 They studied the relationship between allyl
rotation and bidentate phosphorus ligands by X-ray analyses as
well as by NMR spectroscopies and revealed that endo form is
favorable in dithio–molybdenum complexes possessing the dppe
ligand. The observation of complexes 6-Mo and 6-W mentioned
above is consistent with Yih’s results.
General procedures
All manipulations involving air- and moisture-sensitive organo-
metallic compounds were carried out under an atmosphere
of dry argon or nitrogen, which was purified by SICAPENT
(Merck Co., Inc.), by using standard Schlenk-tube or high-
vacuum techniques. All solvents were distilled over appropriate
drying agents prior to use. 1,2-Bis(diphenylphosphino)ethane
The non-symmetrical structures of the complexes 6-Mo and
6-W prevented from obtaining clear information on their
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0
3 9 8 7

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1
Table 4 Variable-temperature 31P{ H} NMR data for complexes 6-Mo and 6-Wa
endo 6-Mo
exo 6-Mo
endo 6-W
exo 6-W
r.t.
57.1 (d, JPP = 24.4 Hz)
85.3 (d, JPP = 24.4 Hz)
(0.70)
59.9 (br)
Overlapped
(0.30)
52.4 (s, JPW = 216.7 Hz)
62.9 (s, JPW = 251.8 Hz)
(0.65)
49.9 (br)
59.7 (br)
(0.35)
90 ◦Cb
57.5 (d, JPP = 28.1 Hz)
85.8 (d, JPP = 28.1 Hz)
50.9 (br)
62.2 (br)
0 ◦
C
57.7 (d, JPP = 27.5 Hz)
85.7 (d, JPP = 27.5 Hz)
(0.70)
60.3 (d, JPP = 36.6 Hz) 52.9 (d, JPP = 4.6 Hz, JPW = 219.7 Hz)
50.4 (d, JPP = 18.3 Hz, JPW = 210.6 Hz)
60.1 (d, JPP = 18.3 Hz, JPW = 239.6 Hz)
(0.35)
85.8 (d, JPP = 36.6 Hz) 63.3 (d, JPP = 4.6 Hz, JPW = 248.7 Hz)
(0.30)
(0.35)
−50 ◦
C
58.9 (d, JPP = 29.0 Hz)
86.6 (d, JPP = 29.0 Hz)
(0.75)
61.2 (d, JPP = 36.6 Hz) 53.7 (s, JPW = 219.7 Hz)
86.5 (d, JPP = 36.6 Hz) 66.3 (s, JPW = 247.2 Hz)
51.3 (d, JPP = 16.8 Hz, JPW = 215.2 Hz)
60.9 (d, JPP = 16.8 Hz, JPW = 239.6 Hz)
(0.30)
(0.25)
(0.70)
a In CD2Cl2 unless otherwise mentioned. Italic numerical values in parentheses indicate integration ratio. Conditions: 161.70 MHz, 5.0 s repetition
time and pulse wide 90◦ (13.0 ls). b In toluene.
3
2
(dppe)21 and [M(g -allyl){g -(NC6H5)2CH}(CO)2(NC5H5)]
1.80 (m, 1H, allyl-CH), 3.00 (d, J = 5.9 Hz, 2H, allyl-CH2), 5.16
(d, J = 7.3 Hz, 2H, amidinato-Ph), 5.91 (m, 3H, amidinato-Ph),
6.88 (d, J = 7.3 Hz, 2H, amidinato-Ph), 7.15 (m, 3H, amidinato-
Ph), 7.69 (s, 2H, phen), 7.84 (dd, J = 7.9, 5.3 Hz, 2H, phen),
8.39 (dd, J = 8.6, 1.3 Hz, 2H, phen), 9.20 (dd, J = 5.3, 1.3 Hz,
2H, phen), 9.41 (s, 1H, amidinato-CH).
8a
(M = Mo; 1-Mo, W; 1-W) were prepared according to
the literature methods. 1,10-Phenanthroline (phen) and 2,2ꢀ-
bipyridine (bpy) were purchased from Kanto Chemical Co.,
Inc., and used as received. Other reagents employed in this
research were commercially available and used without further
purification.
1H, 13C{ H} and 31P{ H} NMR spectra were recorded on
JEOL EX-270, AL-400 and ECA-600 spectrometers at ambient
temperature unless otherwise mentioned. PFG-COSY and 1H–
31P PFG-HMBC spectra were measured on JEOL AL-400 and
1
1
Preparation of allylamidine (3)
Complex 2-Mo (50 mg, 0.088 mmol) and DMSO (3 cm3) were
put in a Schlenk tube and then the reaction mixture was heated
at 90 ◦C for 1 h. The resulted umber solution was loaded on an
alumina column (φ 12 × 100 mm) and eluted with ether–hexane
(1 : 8). The pale yellow band was collected and dried in vacuo
to give 3 as a pale yellow oily material (11 mg, 0.047 mmol,
ECA-600 spectrometers, respectively. 1H and 13C{ H} NMR
1
chemical shifts were reported in ppm relative to internal Me4Si.
31P{ H} NMR chemical shifts were recorded in ppm relative
1
to external H3PO4. All coupling constants were recorded in
Hz. IR spectra were recorded on Perkin-Elmer 1600 FT-IR
and a HORIBA FT-730 spectrometers. High resolution mass
spectroscopy (HRMS) was recorded on a JEOL JMS-SX102.
Elemental analyses were carried out with an LECO CHNS-932.
1
53%). H NMR (d, in CDCl3): 4.66 (dt, J = 5.0, 1.6 Hz, 2H,
=
=
CH2 CHCH2), 5.20 (dd, J = 10.2, 1.6 Hz, 1H, CH2 CHCH2),
=
5.24 (dd, J = 17.2, 1.6 Hz, 1H, CH2 CHCH2), 6.01 (ddt, J =
=
17.2, 10.2, 1.6 Hz, 1H, CH2 CHCH2), 7.01–7.38 (m, 10H,
C6H5), 8.10 (s, 1H, amidine-CH). 13C{ H} NMR (d, in CDCl3):
1
49.4, 116.5, 120.4, 121.2, 123.3, 124.2, 129.0, 129.4, 133.1, 144.3,
150.1, 151.4. HRMS (EI): Calc. for C16H16N2: m/z 236.1313.
Found: 236.1316.
Preparation of [Mo(g3-allyl){g1-(NC6H5)2CH}(CO)2(g2-phen)]
(2-Mo)
Complex 1-Mo (72 mg, 0.15 mmol), phen (32 mg, 0.18 mmol),
and CH2Cl2 (10 cm3) were put in a Schlenk tube. After being
stirred at room temperature for 0.5 h, the volatiles were removed
under reduced pressure. The residual solid was washed with
toluene several times, and then dried in vacuo to give 2-Mo
as a red solid (75 mg, 0.13 mmol, 87%). Analytically pure
2-Mo·CH2Cl2 was obtained by recrystallization from CH2Cl2.
Anal. Calc. for C31H26Cl2MoN4O2: C, 56.98; H, 4.01; N, 8.57.
Found: C, 57.53; H, 4.58; N, 8.55%. IR (mCO, KBr): 1931, 1842.
Preparation of [Mo(g3-allyl){g1-(NC6H5)2CH}(CO)2(g2-bpy)]
(4)
Complex 1-Mo (50 mg, 0.11 mmol), bpy (24 mg, 0.15 mmol) and
CH2Cl2 (5 cm3) were put in a Schlenk tube. After being stirred
at room temperature for 1 h, the volatiles were removed under
reduced pressure. The residual solid was washed with toluene
(2 × 5 cm3), and then dried in vacuo to give 4 as a red solid
(46 mg, 0.084 mmol, 76%). Anal. Calc. for C28H24MoN4O2: C,
61.77; H, 4.44; N, 10.29. Found: C, 61.12; H, 4.22; N, 10.76%.
IR (mCO, KBr): 1928, 1840. 1H NMR (d, in CD2Cl2, at −50 ◦C):
6.99–7.28 (m, 10H, Ph), 7.33 (ddd, J = 7.6, 4.9, 1.2 Hz, 2H,
bpy), 7.83 (ddd, J = 8.3, 7.6, 1.8 Hz, 2H, bpy), 8.25 (s, 1H,
amidinato-CH), 8.38 (ddd, J = 8.3, 1.2, 1.0 Hz, 2H, bpy), 8.63
(ddd, J = 4.9, 1.8, 1.0 Hz, 2H, bpy). The allyl protons were not
able to be characterized.
◦
1H NMR (d, in CD2Cl2, at −40 C): 1.47 (d, J = 9.9 Hz, 2H,
allyl-CH2), 2.72 (tt, J = 9.9, 6.6 Hz, 1H, allyl-CH), 3.16 (d, J =
5.9 Hz, 2H, allyl-CH2), 5.18 (d, J = 7.3 Hz, 2H, amidinato-Ph),
5.93 (m, 3H, amidinato-Ph), 6.84 (m, 3H, amidinato-Ph), 7.16
(m, 2H, amidinato-Ph), 7.65 (s, 2H, phen), 7.79 (dd, J = 7.9,
4.6 Hz, 2H, phen), 8.32 (dd, J = 7.9, 1.3 Hz, 2H, phen), 9.12
(dd, J = 4.6, 1.3 Hz, 2H, phen), 9.39 (s, 1H, amidinato-CH).
Preparation of [W(g3-allyl){g1-(NC6H5)2CH}(CO)2(g2-phen)]
(2-W)
Preparation of [Mo(g3-allyl){g2-(NC6H5)2CH}(CO)2]2(l-dppe)
(5-Mo)
Complex 2-W was prepared from 1-W (55 mg, 0.099 mmol),
phen (21 mg, 0.12 mmol), and CH2Cl2 (5 cm3) in the same
manner as that for 2-Mo. Complex 2-W was isolated as a
red powder (55 mg, 0.084 mmol, 85%). Analytically pure 2-
W·CH2Cl2 was obtained by recrystallization from CH2Cl2. Anal.
Calc. for C31H26Cl2N4O2W: C, 50.23; H, 3.54; N, 7.56. Found: C,
50.02; H, 3.69; N, 7.47%. IR (mCO, KBr): 1921, 1828. 1H NMR
(d, in CD2Cl2, at −60 ◦C): 1.67 (d, J = 9.2 Hz, 2H, allyl-CH2),
Complex 1-Mo (58 mg, 0.12 mmol), dppe (27 mg, 0.068 mmol),
and CH2Cl2 (5 cm3) were put in a Schlenk tube. The reaction
mixture was stirred at room temperature for several hours and
thus an orange solid was precipitated. Hexane (10 cm3) was
added to the reaction mixture. The resulting orange precipitates
were isolated by filtration, washed with hexane (3 × 5 cm3), and
dried in vacuo to give 5-Mo (42 mg, 0.036 mmol, 60%). Anal.
3 9 8 8
D a l t o n T r a n s . , 2 0 0 4 , 3 9 8 2 – 3 9 9 0

View Article Online
Calc. for C62H56Mo2N4O4P2: C, 63.38; H, 4.80; N, 4.77. Found:
C, 62.99; H, 4.87; N, 4.68%. IR (mCO, KBr): 1924, 1843.
concentrated to the volume of ca. 1 cm3. After addition of hexane
(a few drops), the solution was kept in a refrigerator to give red
crystals, which were collected by filtration, washed with hexane
(3 × 5 cm3), and dried in vacuo yielding 6-W·0.5PhMe (32 mg,
0.036 mmol, 56%).
Preparation of [W(g3-allyl){g2-(NC6H5)2CH}(CO)2]2(l-dppe)
(5-W)
Complex 5-W was prepared from complex 1-W (57 mg,
0.10 mmol) and dppe (21 mg, 0.053 mmol) in CH2Cl2 (5 cm3) in
the same manner as that for 5-Mo. Complex 5-W was isolated
as an orange powder (43 mg, 0.032 mmol, 60%). Anal. Calc. for
C62H56N4O4P2W2: C, 55.13; H, 4.18; N, 4.15. Found: C, 54.59;
H, 3.93; N, 4.05%. IR (mCO, KBr): 1916, 1831.
Experimental procedure for X-ray crystallography
Suitable single crystals, except for 5-Mo and 5-W, were obtained
by recrystallization from CH2Cl2 (2-Mo·CH2Cl2), from acetone-
d6 (2-W), or from toluene–hexane (6-Mo·0.5PhMe and 6-
W·0.5PhMe) in a refrigerator and are individually mounted
on glass fibers. Single crystals of 5-Mo and 5-W were directly
obtained from the reaction mixture in CH2Cl2 kept in a refriger-
ator and were individually mounted on glass fibers. Diffraction
measurements of all crystals were made on a Rigaku AFC-
7R automated four-circle diffractometer by using graphite-
Preparation of [Mo(g3-allyl){g2-(NC6H5)2CH}(CO)(g2-dppe)]
(6-Mo)
Method A. Complex 1-Mo (30 mg, 0.064 mmol), dppe
(38 mg, 0.095 mmol) and CH3CN (10 cm3) were put in a Schlenk
tube. After being refluxed overnight, the volatiles were removed
under reduced pressure. The residual solid was treated with
hot hexane to afford an orange powder, which was collected
and dried in vacuo to give 6-Mo (29 mg, 0.038 mmol, 59%).
Analytically pure 6-Mo was obtained by recrystallization from
toluene–hexane as orange crystals containing 0.5 molecules of
toluene solvate. Anal. Calc. for C46.5H44MoN2OP2: C, 69.40; H,
5.51; N, 3.48. Found: C, 69.44; H, 5.61; N, 3.45%. IR (mCO, KBr):
˚
monochromated Mo-Ka radiation (k = 0.71069 A). The data
collections were carried out at −50 ◦C using the x–2h scan
technique to a maximum 2h value of 60.0◦ for all crystals. Cell
constants and an orientation matrix for data collection were
determined from 25 reflections with 2h angles in the range 28.55–
29.78◦ for 2-Mo, 29.66–30.00◦ for 2-W, 29.52–29.96◦ for 5-Mo,
29.80–29.99◦ for 5-W, 29.69–30.00◦ for 6-Mo, and 29.78–29.96◦
for 6-W, respectively. Three standard reflections were monitored
at every 150 measurements. The data collection was performed
on a personal computer. In the reduction of data, Lorentz and
polarization corrections and an empirical absorption correction
(W scan) were made.
◦
1
1776. H NMR (d, in CD2Cl2, at −50 C): endo form; 0.45 (t,
J = 11.0 Hz, 1H, allyl-CH2), 1.91 (br, 1H, PCH2), 2.52–2.88 (m,
3H, PCH2), 3.00 (br, 1H, allyl-CH2), 3.32 (d, J = 12.1 Hz, 1H,
allyl-CH2), 4.32 (d, J = 5.5 Hz, 1H, allyl-CH2), 5.01 (m, 1H,
allyl-CH), 5.91 (d, J = 7.7 Hz, 2H, Ph), 6.57 (t, J = 8.2 Hz,
2H, Ph), 7.65 (d, J = 3.3 Hz, 1H, amidinato-CH), 6.79–7.71
(m, 24H, Ph), 7.87 (m, 2H, Ph). exo form; 1.91 (br, 1H, PCH2),
2.24 (d, J = 11.0 Hz, 2H, allyl-CH2), 2.41 (d, J = 11.5 Hz, 1H,
allyl-CH2), 2.52–2.88 (m, 3H, PCH2), 4.06 (m, 1H, allyl-CH),
4.47 (m, 1H, allyl-CH2), 5.99 (d, J = 7.1 Hz, 2H, Ph), 6.79–7.71
(m, 28H, Ph), 7.72 (d, J = 3.8 Hz, 1H, amidinato-CH).
Crystallographic data and the results of measurements are
summarized in Table 1. The structures were solved by direct
methods (SIR 92)22 for 2-Mo, 2-W, 5-Mo and 6-Mo, or by heavy-
atom Patterson methods (PATTY)23 for 5-W and 6-W, and
expanded using Fourier techniques.24 All of the non-hydrogen
atoms were refined anisotropically. In complexes 2-Mo and 2-
W, all hydrogen atoms were located from difference Fourier
maps and refined isotropically. In complexes 5-Mo, 5-W, 6-
Mo and 6-W, hydrogen atoms were located from difference
Fourier maps and refined atomic coordinates. The isotropic
thermal parameters of those hydrogen atoms were fixed at about
1.5 times that of the preceding carbon atom. In cases of 6-Mo
and 6-W, hydrogen atoms of toluene solvate and allyl protons in
exo form were not assigned. The population of allyl protons
in endo form conformed to that of the parent carbons. All
calculations were performed on an SGI Indy computer using
the teXsan crystallographic software package of Molecular
Structure Corporation.25
Method B. Complex 5-Mo (18 mg, 0.015 mmol), dppe
(11 mg, 0.027 mmol), and CH3CN (5 cm3) were put in a Schlenk
tube. After being refluxed for 4 h, the volatiles were removed
under reduced pressure. The residual solid was recrystallized
from hot hexane to yield 6-Mo (17 mg, 0.022 mmol, 73%).
Preparation of [W(g3-allyl){g2-(NC6H5)2CH}(CO)(g2-dppe)]
(6-W)
Method A. Complex 1-W (48 mg, 0.086 mmol), dppe (47 mg,
0.12 mmol), and toluene (10 cm3) were put in a Schlenk
tube. After being refluxed for 20 h, the volatiles were removed
under reduced pressure. The residual solid was recrystallized
by toluene–hexane to afford red crystals, which were collected
and dried in vacuo to give 6-W containing 0.5 molecules of
toluene solvate (38 mg, 0.043 mmol, 50%). Anal. Calc. for
C46.5H44N2OP2W: C, 62.57; H, 4.97; N, 3.14. Found: C, 62.60; H,
5.01; N, 3.15%. IR (mCO, KBr): 1766. 1H NMR (d, in CD2Cl2, at
−50 ◦C): endo form; 0.74 (t, J = 9.9 Hz, 1H, allyl-CH2), 2.02 (m,
1H, PCH2), 2.68–2.83 (m, 2H, PCH2), 2.89 (br, 1H, allyl-CH2),
3.12 (dt, J = 42.3, 13.2 Hz, 1H, PCH2), 3.28 (d, J = 11.5 Hz, 1H,
allyl-CH2), 4.21 (m, 1H, allyl-CH), 4.26 (br, 1H, allyl-CH2), 5.92
(d, J = 7.7 Hz, 2H, Ph), 6.59 (t, J = 8.2 Hz, 2H, Ph), 6.81–7.46
(m, 24H, Ph), 7.88 (t, J = 9.3 Hz, 2H, Ph), 8.32 (d, J = 2.7 Hz,
1H, amidinato-CH). exo form; 1.50 (d, J = 9.9 Hz, 1H, allyl-
CH2), 2.02 (m, 2H, allyl-CH2), 2.38 (m, 1H, PCH2), 2.56 (m, 1H,
PCH2), 2.68–2.99 (m, 2H, PCH2), 3.97 (m, 1H, allyl-CH2), 4.04
(m, 1H, allyl-CH), 6.11 (d, J = 7.7 Hz, 2H, Ph), 6.81–7.46 (m,
24H, Ph), 7.70 (t, J = 9.0 Hz, 2H, Ph), 7.88 (t, J = 9.3 Hz, 2H,
Ph), 8.33 (d, J = 3.3 Hz, 1H, amidinato-CH).
CCDC reference numbers 244945–244950.
See http://www.rsc.org/suppdata/dt/b4/b410927a/ for cry-
stallographic data in CIF or other electronic format.
Acknowledgements
The authors are grateful to Prof. Kohtaro Osakada, Dr.
Yasushi Nishihara, and Dr Daisuke Takeuchi (Tokyo Institute
of Technology) for their kind help in the elemental analyses. We
thank Dr Noriyuki Suzuki (RIKEN) for the measurement of
high resolution mass spectroscopy. We also thank Mr Tadao
Fukuhara (Research Center, SHISEIDO CO., LTD.), Prof.
Masamichi Nakakoshi and Mr Shinji Ishihara (Instrumental
Analysis Center, Yokohama National University) for their kind
1
help in the measurements of H–31P PFG-HMBC and COSY
spectra.
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