Synthesis and properties of group 9 metal complexes bearing a β-ketophosphenato ligand

Article abstract of DOI:10.1016/j.jorganchem.2009.10.022

A novel β-ketophosphenato ligand bearing a bulky substituent, Tbt(2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), on the phosphorus atom was newly designed and synthesized as a heavier congener of a β-ketoiminato ligand. Rhodium and iridium complexes bearing this new β-ketophosphenato ligand have been synthesized and fully characterized by spectroscopic and elemental analyses together with X-ray crystallographic analyses. The results of NMR spectroscopic studies and the X-ray structural analyses suggested that the β-ketophosphenato ligand has unique electronic features due to the low-coordinated phosphorus atom. Comparison of properties between rhodium β-ketophosphenates 2a,b and rhodium β-ketoiminate 7 revealed the character of the β-ketophosphenato ligand, where the trans influence of the phosphorus atom should be stronger than the nitrogen atom of the β-ketoiminato ligand.

Full text of DOI:10.1016/j.jorganchem.2009.10.022

Journal of Organometallic Chemistry 695 (2010) 1019–1025
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and properties of group 9 metal complexes bearing a
b-ketophosphenato ligand
1
*
Teruyuki Matsumoto, Takahiro Sasamori, Nobuhiro Takeda , Norihiro Tokitoh
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 October 2009
Received in revised form 17 October 2009
Accepted 20 October 2009
Available online 24 October 2009
A
novel b-ketophosphenato ligand bearing
a
bulky substituent, Tbt(2,4,6-tris[bis(trimethyl-
silyl)methyl]phenyl), on the phosphorus atom was newly designed and synthesized as a heavier congener
of a b-ketoiminato ligand. Rhodium and iridium complexes bearing this new b-ketophosphenato ligand
have been synthesized and fully characterized by spectroscopic and elemental analyses together with X-
ray crystallographic analyses. The results of NMR spectroscopic studies and the X-ray structural analyses
suggested that the b-ketophosphenato ligand has unique electronic features due to the low-coordinated
phosphorus atom. Comparison of properties between rhodium b-ketophosphenates 2a,b and rhodium b-
ketoiminate 7 revealed the character of the b-ketophosphenato ligand, where the trans influence of the
phosphorus atom should be stronger than the nitrogen atom of the b-ketoiminato ligand.
Ó 2009 Elsevier B.V. All rights reserved.
Keywords:
Monovalent bidentate ligand
b-Ketophosphenato ligand
Low-coordinated phosphorus ligand
Rhodium complex
Iridium complex
1. Introduction
transfer dehydrogenation of alkanes. Their chemical modifications
are so easy that ligands are fine-tunable for every catalytic
The coordination chemistry of b-diketiminato and b-ketoimina-
to ligands has attracted much interest especially in the fields of
olefin polymerization based on late transition metals [1,2]. The
principal advantage of b-diketiminato and b-ketoiminato ligands
can be summarized as follows: (i) facile preparation, (ii) strong
coordination ability to the transition metal center as a monovalent
and bidentate ligand, and (iii) steric effect afforded by the bulky
substituent on the nitrogen atom(s). Particularly, a b-ketoiminato
ligand features unique properties due to its moderate coordination
ability toward a transition metal center lying between b-diketimi-
nato (stronger) and Schiff-base (weaker) ligands to the same metal
center (Scheme 1) and its unsymmetrical trans effect based on the
difference of the coordinating atoms (nitrogen and oxygen) [2].
On the other hand, P,O-chelating monoanionic ligands, phosphi-
noenolate ligands, have been well-studied [3]. Phosphinoenolates
ligands have sp3-phosphorus atom and enolate moiety for coordi-
nation sites that form five-membered ring chelated with transition
metals. Phosphinoenolate metal complexes have been found to
have wide applications for catalytic reactions especially in telo-
merization of CO2 and butadiene, polymerization of ethylene and
reaction.
In addition, the coordination chemistry of phosphaalkenes has
drawn a great deal of recent attention due to their unique elec-
tronic properties of the C@P double-bond, whose characteristic
low-lying p p accepter
* orbital makes it possible to work as a good
toward a transition metal center [4]. However, it is difficult to iso-
late and handle compounds bearing a P@C double-bond. Kinetic
stabilization afforded by a bulky substituent has been proven to
be very effective for the construction of doubly bonded systems
containing (a) heavier atom(s) [5]. We have also reported the syn-
thesis of a series of doubly bonded systems between heavier group
15 elements, ArE = EAr (E = P, Sb, Bi), as stable compounds by
taking advantage of our original steric protection groups, 2,4,6-
tris[bis(trimethylsilyl)methyl]phenyl(Tbt) and 2,6-bis[bis(trimeth-
ylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl(Bbt) groups,
and revealed their unique properties [6,7].
Recently, we have reported the application of Tbt group toward
the synthesis of an extremely bulky b-diketiminato ligand and
their complexation with group 4 metals [8]. During the course of
our investigations on the low-coordinated species of heavier group
15 elements and the extremely bulky b-diketiminato ligand, we
designed novel b-ketophosphenato ligands 1 [9], which have both
features of b-ketoiminato and low-coordinated phosphorus ligands
[10]. We have preliminarily reported the synthesis and properties
of b-ketophosphenato complexes as touchstones for the elucida-
tion of the properties of b-ketophosphenato ligands 1a,b [11] and
* Corresponding author. Fax: +81 774 38 3209.
E-mail address: tokitoh@boc.kuicr.kyoto-u.ac.jp (N. Tokitoh).
Present address: Department of Chemistry and Chemical Biology and Interna-
1
tional Education and Research Center for Silicon Science (Silicon Center), Graduate
School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.10.022

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T. Matsumoto et al. / Journal of Organometallic Chemistry 695 (2010) 1019–1025
Order of π-bonding ability
R
R
R
O
N
N
N
N
O
β-diketiminate
β-ketoiminate
Schiff-base
SiMe3
Me3Si
Me3Si
SiMe3
Tbt
O
P
1a: R = SiMe3
SiMe3
1b: R = H
SiMe3
Tbt group
β-ketophosphenate
R
Scheme 1. Typical types of monovalent bidentate ligands.
the synthesis and property of a P,N-chelating ligand as phosphorus
analogues of a Schiff-base type ligand [12]. We report here the
synthesis and detailed properties of the rhodium and iridium com-
plexes bearing a b-ketophosphenato ligand.
Fig. 1. ORTEP drawing of 3a with thermal ellipsoid plots (50% probability). The
hydrogen atoms are omitted for clarity.
2. Results and discussion
O atoms through the lithiation. The reaction of [4aꢁ(OEt2)]2 with
[RhCl(cod)]2 at room temperature in THF resulted in the formation
of rhodium b-ketophosphenate 2a in 98% yield. In contrast to the
case of lithiation of 3a, the reaction of 3b with LDA under the same
conditions afforded a complicated mixture as judged by the 1H and
31P NMR spectra. Although the purification and identification of
the resulting products failed, the addition of [RhCl(cod)]2 to the
reaction mixture in situ gave stable rhodium b-ketophosphenate
2b in 26% yield (from 3b) (Scheme 3).
Since it is important to evaluate the properties of b-ketopho-
sphenato ligand as compared with those of b-ketoiminato ligands,
rhodium b-ketoiminate 7 was synthesized by the reaction of
[RhCl(cod)]2 with the corresponding lithium b-ketoiminate 6,
which was prepared from b-enaminoketone 5 [15] and n-butyl
lithium (Scheme 4).
2.1. Synthesis of ligand precursors 3a,b
Ligand precursors 3a,b were synthesized as shown in Scheme 2.
Tbt-substituted silylphosphine was synthesized in a good yield by
modifying the reported method [13], i.e., the treatment of
TbtPH(Li) with trimethylsilyl chloride. Since Tbt-substituted silyl-
phosphine was highly reactive toward water and oxygen, it was
used for the next reaction without further purification. When the
Tbt-substituted silylphosphine was treated with 3-butyn-2-one,
3a was obtained via silylphosphination toward carbonyl-activated
carbon–carbon triple bond [14]. It was found that the silylphosph-
ination reaction proceeded in syn-fashion. a-Carbonyl-substituted
trimethylsilyl group of 3a was removed with potassium fluoride
to afford 3b. While 3a is inert toward water and oxygen, 3b grad-
ually decomposed in the air to afford oxidized compounds. E/Z
isomerization of 3a or 3b was not observed under ambient
conditions.
The molecular structure of 3a is shown in Fig. 1. C1–C2 and
C3–O1 bond lengths are 1.345(4) and 1.222(4) Å, respectively, which
are in the range of typical C@C and C@O double-bond lengths.
P1–C1 and C2–C3 bond lengths are 1.808(3) and 1.501(4) Å,
respectively, which are in the range of typical C–C single-bond
lengths. The NMR spectroscopic properties of precursors 3a,b have
also been revealed. The 31P NMR spectra of 3a,b showed signals at
the same value, ꢀ79 ppm, which is a typical chemical shift for sec-
ondary phosphines. In the 1H NMR spectra of 3b, the coupling con-
The reaction of [4aꢁ(OEt2)]2 with [IrCl(cod)]2 in THF resulted in
the formation of iridium b-ketophosphenate 8b bearing ligand 1b
in 94% yield as shown in Scheme 5. In this reaction, no formation
of 8a bearing ligand 1a was observed. Unexpectedly, the SiMe3
group of [4aꢁ(OEt2)]2 was lost via the complexation reaction, and
the fate of SiMe3 group is unclear at present.
2.3. Structural properties of lithium b-ketophosphenate 4a, rhodium
b-ketophosphenates 2a,b, and iridium b-ketophosphenate 8b
The structure of lithium complex 4a was revealed by the X-ray
crystallographic analysis (Fig. 3). Since there is no notable differ-
ence between the two crystallographically independent molecules
in the unit cell, one of them was shown in Fig. 2. The lithium
b-ketophosphenate exhibits a dimeric structure. The ligand backbone
P1–C1–C2–C3–O1 showed planar structure and the lithium atom
was out of the plane. In the P1–C1–C2–C3–O1 skeleton, the
every bond length was medium values between those of the corre-
sponding single and double-bonds, suggesting their delocalized
stant between
a-carbonyl methine proton and TbtPH-substituted
methine proton is 17 Hz, supporting the structure of 3b.
2.2. Synthesis of lithium b-ketophosphenate 4a, rhodium
b-ketophsphenates 2a,b and iridium b-ketophosphenate 8b
Deprotonation reaction of 3a with LDA in THF afforded lithium
b-ketophosphenate [4aꢁ(OEt2)]2, which was reasonably character-
ized by the spectroscopic and X-ray crystallographic analyses. It
was found that the C@C moiety of 3a rotated to form the cyclic
structure with the central lithium atom coordinated by the P and
p
-electrons. The NMR spectroscopic properties of lithium b-keto-
phosphenate 4a have also been revealed. The 31P NMR spectra of
4a showed a signal in a relatively low field (162 ppm) which
should indicate the sp2-hybridization of the phosphorus atom.
O
H
O
H
O
SiMe3
H
KF, H2O
Tbt
P
Tbt
Tbt
P
H
P
H
C6H6
40 ºC
62%
THF
60 ºC
76%
SiMe3
H
3b
3a
Scheme 2. Synthesis of precursors 3a, 3b.

T. Matsumoto et al. / Journal of Organometallic Chemistry 695 (2010) 1019–1025
1021
(Et2O)
Li
Tbt
R = SiMe3
O
P
(cod)
Rh
SiMe3
[4a•(OEt2)]2
2
Tbt
O
H
O
P
[RhCl(cod)]2
LDA
Tbt
P
H
THF
r. t.
THF
–40 ºC
R
R
complicated mixture
3a: R = SiMe3
3b: R = H
2a: R = SiMe3
2b: R = H
R = H
cod = 1,5-cyclooctadiene
Scheme 3. Synthesis of rhodium b-ketophosphenate 2a,b.
Table 1
Observed and calculated structural parameters for 2b, 2b0, 7 and 70. (Dmp = 2,6-di-
methylphenyl).
(Et2O)n
(cod)
Dip
Li
Dip
Rh Dip
n-BuLi
[RhCl(cod)]2
O
HN
O
N
O
N
ether
0 ºC
ether
0 ºC
C4'
C4
C5'
C5
5
7
6
Dip = 2,6-diisopropylphenyl
Scheme 4. Synthesis of rhodium b-ketoiminate 7.
Ar
Rh
C2
E
O
E = P, R = H
E = N, R = Me
(Et2O)
Li
(cod)
Ir
C1
C3
Tbt
R
Tbt
[IrCl(cod)]2
O
P
O
P
THF
60 ºC
SiMe3
2
Calculateda
[4a•(OEt2)]2
8b
Bond lengths (Å) Observed
2b
E = P
Ar = Tbt
7
2b0
E = P
2b
E = P
70
E = N
Scheme 5. Synthesis of iridium b-ketophosphenate 8b.
E = N
Ar = Dip
Ar = Dmp Ar = Tbt Ar = Dmp
Rh–E
E–C1
2.2404(8) 2.098(1) 2.3
2.332
1.708
1.405
1.398
1.286
2.089
2.146
2.174
2.252
2.214
2.136
1.331
1.416
1.393
1.281
2.064
2.167
2.191
2.201
2.174
1.698(3)
1.396(5)
1.387(5)
1.278(4)
2.043(2)
2.108(3)
2.119(4)
2.195(4)
2.173(4)
1.325(2) 1.723
1.419(3) 1.398
1.372(3) 1.409
1.289(2) 1.28
2.040(1) 2.095
2.116(2) 2.152
2.140(2) 2.171
2.152(2) 2.263
2.125(2) 2.242
C1–C2
C2–C3
C3–O1
O1–Rh
Rh–C4
Rh–C04
Rh–C5
Rh–C05
a
Optimized at B3LYP/6-31G(d) (6-31G(3d) for Si, P: lanl2DZ for Rh).
were similar to each other. These structural features suggested
the stronger trans influence of the phosphorus moiety of b-keto-
phosphenato ligand 1b as compared with its oxygen moiety in
contrast to almost equal degree of trans influence of the both sides
of N and O in 7. Such unique unsymmetrical electronic feature of
Fig. 2. Molecular structure of the lithium b-ketophosphenate [4aꢁ(OEt2)]2ꢁ(0.5hex-
ane) (50% probability). Hydrogen atoms, hexane and diethylether were omitted for
clarity. Selected bond lengths (Å): Li1–P1, 2.613(5); Li1–O1, (3); P1–C1, 1.711(3);
C1–C2, 1.432(4); C2–C3 1.400(4); C3–O1, 1.297(4).
b-ketophosphenato ligand 1b should reflect the high
r-donating
ability due to the electropositive phosphorus atom and the
low-lying p* orbital of sp2-hybridized phosphorus atom making
the back donation from the rhodium stronger.
Structures of rhodium complexes 2a,b and 7 were revealed by
the X-ray crystallographic analyses (Fig. 3), and the observed struc-
tural parameters were summarized in Table 1. The phosphorus
atoms of 2a and 2b were found to exhibit an sp2-hybridization
on the basis of the almost planar geometry (the sum of the angles
around the P atom is 359.6°). In addition, it was found that both
2a,b and 7 showed an almost planar structure for the central six-
membered ring moiety, [–Rh–O–C–C–C–E–] (E = N and P), where
the every bond length of the central hexagonal ring was medium
values between those of the corresponding single and double-
Theoretical calculations have been performed for the model
molecules bearing a less hindered substituent (Dmp; 2,6-dimethyl-
phenyl) instead of a Tbt or Dip group, i.e., rhodium b-ketophos-
phenate 2b0 and rhodium b-ketoiminate 70, optimized at B3LYP/
6-31G(d) (6-31G(3d) for Si, P: lanl2DZ for Rh). The optimized struc-
tural parameters of 70 were similar to those observed for 7, indicat-
ing the relatively bulky Dip group less affected the structure of the
rhodium b-ketoiminate skeleton. However, the optimized struc-
ture of 2b0 showed a bent structure for the central six-membered
ring moiety in contrast to the observed planar structure of 2b.
Although the C–C and C–O bonds of 2b0 were found to be highly
conjugated as judged by their bond lengths, the phosphorus atom
showed the pyramidal geometry (the sum of the angles around the
bonds, suggesting their delocalized p-electrons. It should be noted
that the two Rh–(cod) distances of 2a,b were apparently different
from each other, that is, the bond lengths of Rh–C4 and Rh–C40
were shorter than those of Rh–C5 and Rh–C50, though those of 7

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T. Matsumoto et al. / Journal of Organometallic Chemistry 695 (2010) 1019–1025
P atom is 347.1°), which is indicative of its sp3-hybridization.
Therefore, it can be concluded that the extremely bulky Tbt group
plays two important roles as follows: (i) kinetic stabilization for
the reactive sp2-phosphorus center and (ii) steric effect of the up-
right geometry of two CH(SiMe3)2 moieties at ortho positions for
keeping the planar structure of the b-ketophosphenato ligand with
sp2-hybridized phosphorus atom and preventing the phosphorus
atom from having a pyramidal structure of sp3-character [16].
Actually, the theoretically optimized structure of the real molecule
2b showed the structural parameters similar to those experimen-
tally observed with the planar skeleton of the central six-mem-
bered ring (the sum of angles around the P atom is 359.8°).
The NMR spectroscopic properties of rhodium b-ketophosphen-
ates 2a,b have also been revealed. The 31P NMR spectra of 2a,b
showed doublet signals in a relatively low-field region, 129
(1JPRh = 174 Hz) and 120 (1JPRh = 175 Hz) ppm, respectively, which
are characteristic of sp2-hybridized phosphorus atoms. The ob-
(cod)
Rh
(nbd)
Rh
Tbt
Tbt
O
P
O
P
C6D6
40 ºC
3b
9
nbd = norbornadiene
Scheme 6. Ligand-exchange reaction of rhodium b-ketophosphenate.
C6D6. Heating of rhodium b-ketophosphenate 2b in the presence of
norbornadiene (10 eq.) in C6D6 at 40 °C for 5 h afforded the corre-
sponding diene-exchanged product
though no diene-exchange reaction was observed in the case of
heating of rhodium b-ketoiminate 7 under the same conditions.
The lower barrier of the diene-exchange reaction of 3b than that
of 7 would be due to the strong trans effect of the P atoms of the
b-ketophosphenato ligand 1b (Scheme 6).
8 almost quantitatively,
1
3. Conclusion
served coupling constants of 2a,b, JPRh, were in the typical range
of those for rhodium–phosphine or –phosphide complexes [17].
In the 13C NMR spectra of 2a,b, the chemical shifts of C5 and C05
(96.5 for 2a, 96.0 for 2b) were observed in a lower-field region than
The first stable rhodium b-ketophosphenates 2a,b and iridium
b-ketophosphenate 9b have been synthesized as stable com-
pounds. Their unique properties due to the intrinsic nature of the
sp2-hybridized P atom have been revealed based on the compari-
son with those of rhodium b-ketoiminate 7. The unique unsym-
metrical trans influence of b-ketophosphenato ligands 1 was
suggested by the spectroscopic and crystallographic analyses of
the corresponding complexes, where that of the phosphorus moi-
ety should be stronger than the oxygen moieties in contrast to
the similar degree of trans influence of the both sides of N and O
atoms in a b-ketoiminato ligand. The b-ketophosphenato ligand
1a,b should be a potentially good candidate as one of the unique
ligands to make great progress in the catalytic chemistry. Further
investigation of their chemical reactivity and catalytic ability of
the newly obtained metal complexes is currently in progress.
those of C4 and C0 (64.7 for 2a, 64.4 for 2b) (the atom numberings
4
are according to those shown in Table 1). Thus, the NMR spectra of
2a,b also suggested the stronger trans influence of the P atom than
that of O atom in b-ketophosphenato ligands 1. On the other hand,
the 13C NMR spectra of rhodium b-ketoiminate 7 showed the sig-
nals for its C4 (C0 ) and C5(C0 ) atoms at 75.9 and 81.6 ppm, respec-
4
5
tively, indicating the similar degree of the trans influence of O and
N atoms in b-ketoiminato ligand.
The 31P NMR spectra of 8b showed a signal in a relatively low field
(121 ppm)which shouldbecharacteristic ofsp2-hybridizedphospho-
rus atoms, supporting its structural features similar to those of 2b.
2.4. Thermalligand-exchangereactionofrhodiumb-ketophosphenate 2a
Thermal ligand-exchange reaction was examined to elucidate
the difference of the electronic property between b-ketophosphe-
nato ligand and b-ketoiminato ligand from the viewpoint of trans
effect. The NMR studies of 3b showed that it underwent very slow
ligand-exchange reaction of the cyclooctadiene moiety in the pres-
ence of an excess amount of norbornadiene at room temperature in
4. Experimental
4.1. General experimental details
All experiments were performed under an argon atmosphere
unless otherwise noted. All solvents were purified by standard
Fig. 3. (a, b) ORTEP drawing of 2b with thermal ellipsoid plots (50% probability). Hydrogen atoms are omitted for clarity. (c) Optimized structure of 2b0. Hydrogen atoms are
omitted for clarity. (d) Optimized structure of 2b. Hydrogen atoms are omitted for clarity.

T. Matsumoto et al. / Journal of Organometallic Chemistry 695 (2010) 1019–1025
1023
methods and/or The Ultimate Solvent System (Glass Contour
4.4. Synthesis of precursor 3b
Company) [18] prior to use. 1H NMR (400 or 300 MHz) and
13C NMR (100 or 75 MHz) spectra were measured in CDCl3 or
C6D6 with a JEOL JNM AL-400 or JEOL JNM AL-300 spectrome-
ter. A signal due to CHCl3 (7.25 ppm) or C6D5H (7.15 ppm)
was used as an internal standard in 1H NMR, and that due to
CDCl3 (77.0 ppm) or C6D6 (128 ppm) was used in 13C NMR.
Multiplicity of signals in 13C NMR spectra was determined by
DEPT technique. Mass spectral data were obtained on a JEOL
JMS-700 spectrometer (FAB) or BRUKER micro TOF focus-Kci
(ESI). GPLC (gel permeation liquid chromatography) was per-
formed on an LC-908 or LC-918 (Japan Analytical Industry Co.,
Ltd.) equipped with JAIGEL 1H and 2H columns (eluent: toluene
or chloroform). Preparative thin-layer chromatography (PTLC)
and Wet column chromatography (WCC) were performed with
Merck Kieselgel 60 PF254 and Wakogel C-200, respectively. All
melting points were determined on a Yanaco micro melting
point apparatus and are uncorrected. Elemental analyses were
carried out at the Microanalytical Laboratory of the Institute
for Chemical Research, Kyoto University. TbtPH2 [19] and b-ena-
minoketone 5 [16] were prepared according to the reported
procedures.
A THF solution (30 mL) of 3a (1.00 g, 1.38 mmol) and KF (80 mg,
1.4 mmol) was stirred at 60 °C for 1 h. After removal of the solvent
under reduced pressure, the crude product was dissolved in hex-
ane and then filtered through CeliteÒ. The filtrate was evaporated
to afford 3b (76% yield as judged by 1H NMR). 3b: colorless solid;
1H NMR (300 MHz, C6D6, 298 K) d 0.13–0.18 (br, 54H), 1.58 (s,
1
3
1H), 1.90 (s, 3H), 2.84 (s, 2H), 4.95 (dd, JPH = 230 Hz, JHH = 7 Hz,
3
1H), 6.39 (dd, JHH = 7, 17 Hz, 1H), 6.56 (s, 1H), 6.67 (s, 1H), 7.17
(ddd, 2JPH = 24 Hz, 3JHH = 7 Hz, 17 Hz, 1H). 31P{1H} NMR
(120 MHz, CDCl3, 298 K) d ꢀ79. High-resolution MS (FAB) m/z Calc.
for C31H66OPSi6 653.3467. Found: 353.3453 ([M+H]+) The chemical
data of 3b could not be collected satisfactorily due to the contam-
ination of small amount of inseparable by-products. Since it under-
went gradual decomposition leading to the formation of by-products
through separation procedures, the crude mixture was used in the
next reaction without further purification.
4.5. Synthesis of [4aꢁ(OEt2)]2
To a THF solution (5 mL) of 3a (50 mg, 0.069 mmol) was added a
THF solution (2 mL) of lithium diisopropylamide (7.7 mg,
0.072 mmol) at ꢀ40 °C. After stirring for 8 h, the solvent was re-
moved under reduced pressure. The crude product was dissolved
in benzene and heated at 60 °C. The solvent was removed under re-
duced pressure to afford [4aꢁ(OEt2)]2 (51 mg, 0.063 mmol, 92%).
[4aꢁ(OEt2)]2: pale yellow crystals, m.p. 195–198 °C (decomp.); 1H
NMR (300 MHz, C6D6, 298 K) d 0.14–0.29 (br, 54H), 0.35 (s, 9H),
4.2. Synthesis of TbtPH(SiMe3)
To
a diethylether solution (10 mL) of TbtPH2 (584 mg,
1.00 mmol) was added n-butyl lithium (1.51 M hexane solu-
tion, 0.79 mL, 1.2 mmol) at ꢀ78 °C. After stirring at ꢀ78 °C
for 1 h, trimethylsilyl chloride (1.1 mL, 1.2 mmol) was added.
The reaction mixture was gradually warmed upto room tem-
perature and was stirred for 1.5 h. After removal of the solvent
under reduced pressure, the crude product was dissolved in
hexane and then filtered through CeliteÒ. The filtrate was
evaporated to afford TbtPH(SiMe3) (643 mg, 0.978 mmol, 98%).
TbtPH(SiMe3): colorless crystals, m.p. 117–118 °C (decomp.);
3
1.12 (t, JHH = 7 Hz, 6H), 1.52 (s, 1H), 2.36 (s, 3H), 3.07 (s, 1H),
3
3.21 (s, 1H) 3.39 (q, JHH = 7 Hz, 4H), 6.62 (s, 1H), 6.73 (s, 1H),
2
8.75 (d, JPH = 21 Hz, 1H); 31P{1H} NMR (120 MHz, C6D6, 298 K) d
162. The satisfactory data for elemental analysis of [4aꢁ(OEt2)]2
could not be obtained due to its incombustibility.
4.6. Synthesis of rhodium complex 2a
1H NMR (300 MHz, CDCl3, 298 K)
d 0.16 (s, 18H), 0.25 (s,
3
36H), 0.32 (d, JPH = 5 Hz, 9H), 1.43 (s, 1H), 2.49 (s, 2H), 3.61
To a THF solution (5 mL) of [4aꢁ(OEt2)]2 (40 mg, 0.050 mmol)
was added [RhCl(cod)]2 (12 mg, 0.025 mmol) at room temperature.
The reaction mixture was stirred at room temperature for 10 h.
After the solvent was removed under reduced pressure, benzene
was added to the crude product. Then, the suspension was filtered
through CeliteÒ. After the solvent of the filtrate was removed, the
residue was washed with hexane to afford rhodium complex 2a
(46 mg, 0.49 mmol, 98%). 2a: orange crystals, m.p. 130–134 °C (de-
comp.); (300 MHz, C6D6, 298 K) d 0.16 (s, 18H), 0.19 (s, 18H), 0.28
(s, 18H), 0.38 (s, 9H), 1.46 (s, 1H), 1.87 (m, 2H), 2.05 (m, 2H), 2.28
(d, 3H), 2.34 (m, 2H), 2.46 (m, 2H), 3.06 (br, 1H), 3.18 (br, 1H), 4.10
(m, 2H), 5.43 (m, 2H), 6.57 (s, 1H), 6.69 (s, 1H), 8.42 (d, 2JPH = 13 Hz,
1H); 13C{1H} NMR (75 MHz, C6D6, 298 K) d 0.6 (CH3), 0.7 (CH3), 1.0
(CH3), 1.4 (CH3), 1.6 (CH3), 1.7 (CH3), 1.9 (CH3), 28.5 (CH2), 29.9 (d,
J = 4 Hz, CH3), 30.1 (CH), 30.2 (CH), 32.3 (CH), 33.7 (d, J = 4 Hz, CH2),
65.1 (d, J = 14 Hz, CH), 96.9 (dd, J = 8, 13 Hz, CH), 113.6 (d, J = 6 Hz,
C), 122.5 (CH), 127.3 (CH), 145.4 (C), 151.3 (C), 164.9 (d, J = 10 Hz,
CH), 176.7 (d, J = 26 Hz, C); 31P{1H} NMR (120 MHz, C6D6, 298 K) d
1
(d, JPH = 214 Hz, 1H), 6.57 (s, 1H), 6.69 (s, 1H); 31P{1H} NMR
(120 MHz, C6D6, 298 K) d ꢀ143. High-resolution MS (FAB) m/z
Calc. for C30H70OPSi7 657.3600. Found: 657.3586 ([M+H]+).
Anal. Calc. for C30H69OPSi7: C, 54.81; H, 10.58. Found: C,
54.82; H, 10.69%.
4.3. Synthesis of precursor 3a
To
1.90 mmol) was added a benzene solution (100 mL) of 3-bu-
tyn-2-one (446 L, 5.70 mmol) dropwise at room temperature.
a benzene solution (30 mL) of TbtPH(SiMe3) (1.25 g,
l
The reaction mixture was stirred at 40 °C for 10 h. After removal
of the solvent under reduced pressure, the purification of the
crude product with WCC (hexane/ether = 5/1) gave 3a (862 mg,
1.18 mmol, 62%). 3a: colorless crystals, m.p. 138–140 °C (de-
comp.); 1H NMR (300 MHz, CDCl3, 298 K) d 0.00 (s, 18H), 0.04
(s, 36H), 0.31 (s, 9H), 1.34 (s, 1H), 2.14 (s, 3H), 2.60 (s, 1H),
1
3
1
2.64 (s, 1H), 5.08 (dd, JPH = 231 Hz, JHH = 7 Hz, 1H), 6.37 (s,
129 (d, JPRh = 174 Hz). High-resolution MS (FAB) m/z Calc. for
2
3
1H), 6.49 (s, 1H), 7.15 (dd, JPH = 8 Hz, JHH = 7 Hz, 1H);
13C{1H} NMR (75 MHz, CDCl3, 298 K) d 0.0 (CH3), 0.1 (CH3),
0.2 (CH3), 0.3 (CH3), 0.4 (CH3), 0.5 (CH3), 26.4 (CH3), 28.7
C42H84OPRhSi7: 934.3700. Found: 934.3708 ([M]+). Anal. Calc. for
C42H84OPRhSi7: C, 53.92; H, 9.05. Found: C, 53.94; H, 9.06%.
2
(CH), 30.2 (CH), 121.6 (CH), 122.5(d, JPC = 3 Hz, C), 126.5 (CH),
4.7. Synthesis of rhodium complex 2b
1
144.6 (C), 150.2 (C), 152.4 (d, JPC = 14 Hz, C), 152.9 (d,
1JPC = 26 Hz, CH), 202.8 (d, JPC = 11 Hz, C); 31P{1H} NMR
To a THF solution (5 mL) of 3b (50 mg, 0.069 mmol) was added
a solution of lithium diisopropylamide (7.7 mg 0.072 mmol) in THF
(2 mL) at ꢀ40 °C. After stirring for 8 h, the solvent was removed
under reduced pressure. The residue was dissolved in THF (5 mL)
and [RhCl(cod)]2 (17 mg, 0.035 mmol) was added. The reaction
2
(120 MHz, CDCl3, 298 K) d ꢀ79. High-resolution MS (FAB) m/z
Calc. for C34H73OPSi7 724.3784. Found: 724.3763 ([M]+). Anal.
Calc. for C34H73OPSi7: C, 56.29; H, 10.14. Found: C, 56.11; H,
10.25%.

1024
T. Matsumoto et al. / Journal of Organometallic Chemistry 695 (2010) 1019–1025
mixture was stirred for 10 h. After the solvent was removed under
reduced pressure, insoluble inorganic salts were removed by filtra-
tion through CeliteÒ with benzene. After the solvent of the filtrate
was removed, the residue was washed with hexane to afford 2b
(15 mg, 0.018 mmol, 26% from 3b). 2b: orange crystals, m.p.
130–131 °C (decomp.); 1H NMR (300 MHz, C6D6, 298 K) d 0.17 (s,
18H), 0.20 (s, 18H), 0.29 (br, 18H), 1.48 (s, 1H), 1.88 (m, 2H),
2.03 (m, 2H), 2.07 (d, 3H), 2.30 (m, 2H), 2.47 (m, 2H), 3.13 (s,
1H), 3.25 (br, 1H), 4.16 (m, 2H), 5.48 (m, 2H), 6.28 (dd, 3JHH = 10 Hz,
4.10. Thermolysis of rhodium complex 2b in the presence of
norbornadiene
To a C6D6 solution (0.7 mL) of 2b (6.9 mg, 8.0
lmol) in a 5u
NMR tube was added norbornadiene (8.1 L, 0.080 mmol). The
l
reaction mixture was degassed and sealed in the NMR tube. After
heating at 40 °C for 5 h, the starting material was found to disap-
pear as judged by the 1H NMR spectrum. The NMR tube was
opened in a glove box filled with argon gas, and the solvent and
dienes were removed under reduced pressure to afford 9 (6.6 mg,
2
3JPH = 28 Hz, 1H), 6.59 (s, 1H), 6.71 (s, 1H), 8.23 (dd, JPH = 13 Hz,
3JHH = 10 Hz, 1H); 13C{1H} NMR (75 MHz, C6D6, 298 K) d 1.0 (CH3)
1.4 (CH3), 1.8 (CH3), 28.3 (CH2), 28.7 (d, J = 4 Hz, CH3), 30.1
(CH), 30.3 (CH), 31.0 (CH), 33.4 (d, J = 4 Hz, CH), 64.4 (d, J = 14 Hz,
CH), 95.7 (dd, J = 9, 13 Hz, CH), 107.9 (d, J = 4 Hz, CH), 122.5
(CH), 127.3 (CH), 145.1 (C), 151.1 (C), 160.1 (d, J = 18 Hz, CH),
173.0 (d, J = 23 Hz, C); 31P{1H} NMR (120 MHz, C6D6, 298 K)
7.4 l
mol, 97%). 9: orange crystals, m.p. 211–212 °C (decomp.); 1H
NMR (300 MHz, C6D6, 298 K) d 0.17 (s, 18H), 0.20 (s, 18H), 0.28
(br, 18H), 1.12 (m, 1H), 1.24 (m, 1H), 1.47 (s, 1H), 2.11 (d, 3H),
3.24 (brs, 1H), 3.37 (brs, 1H), 3.51 (brs, 2H), 4.06 (m, 2H), 4.98
3
3
(m, 2H), 6.33 (dd, JHH = 10 Hz, JPH = 28 Hz, 1H), 6.58 (br, 1H),
6.69 (s, 1H), 8.22 (dd, 2J = 14 Hz, 3J = 10 Hz, 1H); 13C{1H} NMR
(75 MHz, C6D6, 298 K) d 1.5 (CH3) 2.0 (CH3), 2.1 (CH3), 29.1 (d,
J = 6 Hz, CH3), 30.9 (CH), 31.5 (CH), 46.1 (d, J = 11 Hz, CH), 50.1 (s,
CH), 62.9 (s, CH2),74.8 (dd, J = 7, 12 Hz, CH), 109.0 (s, CH), 122.9
(CH), 127.6 (CH), 145.5 (C), 151.0 (C), 159.7 (d, J = 16 Hz, CH),
174.4 (d, J = 22 Hz, C); 31P{1H} NMR (120 MHz, C6D6, 298 K) d
1
d 120 (d, JPRh = 175 Hz). High-resolution MS (FAB) m/z Calc.
for C39H77OPRhSi6 863.3383. Found: 863.3372 ([M+H]+). Anal.
Calc. for C39H76OPRhSi6: C, 54.25; H, 8.87. Found: C, 54.26; H,
8.95%.
1
133 (d, JPRh = 197 Hz). LRMS (ESI, negative): m/z 831, Calc. for
4.8. Synthesis of rhodium complex 7
C37H69OPRhSi6 831 ([MꢀMe]ꢀ). Since it was difficult to obtain a
satisfactory result for the elemental analysis of 9 due to the extre-
mely high air-, moisture-, and light-sensitivity, the purity was con-
firmed by the 1H NMR spectrum.
To
(150 mg, 0.578 mmol) was added n-butyl lithium (1.51 M hexane
solution, 463 L, 0.694 mmol) at 0 °C. After the reaction mixture
a diethylether solution (20 mL) of b-enaminoketone 5
l
was stirred at 0 °C for 15 min, [RhCl(cod)]2 (142 mg, 0.289 mmol)
was added. After stirring for 2 h, the solvent was removed under
reduced pressure. The residue was washed with hexane to afford
7 (89 mg, 0.19 mmol, 33%). 7: orange crystals; m.p. 167 °C (de-
5. X-ray crystallographic analysis of 2b, 3a,
[4aꢁ(OEt2)]2ꢁ(0.5hexane) and 7
The intensity data were collected on a RIGAKU Saturn70 CCD
3
comp.); 1H NMR (300 MHz, C6D6, 298 K) d 1.01 (d, JHH = 7 Hz,
(system) with VariMax Mo Optic using Mo
(k = 0.71070 Å) for 2b, and on a Rigaku/MSC Mercury CCD diffrac-
tometer with graphite monochromated Mo radiation
Ka radiation
3
6H) 1.37 (d, JHH = 7 Hz, 6H), 1.51 (s, 3H), 1.54 (m, 2H), 1.66 (m,
2H), 2.01 (s, 3H), 2.24 (m, 4H) 2.90 (m, 2H), 3.46 (sept, 3JHH = 7 Hz,
2H), 4.74 (m, 2H), 5.08 (s, 1H), 7.04 (s, 3H); 13C{1H} NMR (75 MHz,
C6D6, 298 K); d 24.0 (CH3), 25.0 (CH3), 25.2 (CH3), 26.6 (CH3), 28.1
Ka
(k = 0.71070 Å) for 3a, [4aꢁ(OEt2)]2ꢁ(0.5hexane) and 7. Single crys-
tals suitable for X-ray analysis were obtained by slow recrystalliza-
tion from THF/benzene (for 2b), hexane (for 3a), Et2O/hexane (for
[4aꢁ(OEt2)]2ꢁ(0.5hexane)) and benzene (for 7). The single crystals
were mounted on a glass fiber. The structures were solved by a di-
rect method (SHELXS-97) [20] and refined by full-matrix least-
squares procedures on F2 for all reflections (SHELXL-97) [21]. All
hydrogen atoms were placed using AFIX instructions, while all
other atoms were refined anisotropically.
1
(CH), 29.3 (CH2), 31.7 (CH2), 76.0 (d, JRhC = 14 Hz, CH), 81.6 (d,
1JRhC = 12 Hz, CH), 97.7 (CH), 124.0 (CH), 126.0 (CH), 141.2 (C),
146.1 (C), 165.2 (C), 177.7 (C). High-resolution MS (FAB) m/z Calc.
for C25H36ONRh 469.1852. Found: 469.1854 ([M]+). Anal. Calc. for
C25H36ONRh: C, 63.96; H, 7.73; N 2.98. Found: C, 63.91; H, 7.77;
N 3.03%.
Crystal data for 2b: C39H76OPRhSi6, M = 863.42, T = 103(2) K, tri-
ꢀ
4.9. Synthesis of iridium complex 8b
clinic, P1 (no. 2), a = 10.0909(2) Å, b = 11.1677(2) Å, c = 22.2560(4)
Å,
a
= 102.3125(13)°, b = 90.6913(8)°,
c
l
= 104.4184(10)°, V =
To a THF solution (25 mL) of [4aꢁ(OEt2)]2 (172 mg, 0.10 mmol)
was added [IrCl(cod)]2 (70 mg, 0.10 mmol) at room temperature.
The reaction mixture was stirred at 60 °C for 10 h. After the solvent
was removed under reduced pressure, benzene was added to the
crude product. Then, the suspension was filtered through CeliteÒ.
After the solvent of the filtrate was removed, the residue was
washed with hexane to afford iridium complex 8b (188 mg,
0.094 mmol, 94%). 8b: orange crystals, m.p. 170–171 °C (decomp.);
1H NMR (300 MHz, C6D6, 298 K) d 0.17 (s, 18H), 0.18 (s, 18H), 0.29
(br, 18H), 1.49 (s, 1H), 1.86 (m, 2H), 2.01 (m, 2H), 2.06 (d, 3H), 2.23
(m, 2H), 2.38 (m, 2H), 3.07 (br, 1H), 3.19 (br, 1H), 4.02 (m, 2H), 5.20
(m, 2H), 6.44 (dd, J = 11, 29 Hz, 1H), 6.60 (br, 1H), 6.73 (br, 1H),
2367.57(8) Å3, Z = 2, Dcalc = 1.211 g cmꢀ3
,
= 0.573 mmꢀ1, 2hmax
=
51.0, 25 098 measured reflections, 8695 independent reflections
(Rint = 0.0254), 637 refined parameters, GOF = 1.107, R1 = 0.0396
and wR2 = 0.0926 [I > 2r(I)], R1 = 0. 0441 and wR2 = 0.0950 [for all
data], largest diff. peak and hole 0.980 and ꢀ0.710 e Åꢀ3
.
Crystal data for 3a: C34H73OPSi7, M = 725.5, T = 103(2) K, mono-
ꢀ
clinic, triclinic, P1 (no. 2), a = 12.374(5) Å, b = 12.978(5) Å,
c = 16.641(6) Å,
a
= 94.725(3)°, b = 104.348(3)°,
c
l
= 116.225(3)°,
V = 2265.2(15) Å3, Z = 2, Dcalc = 1.064 g cmꢀ3
,
= 0.269 mmꢀ1
,
2hmax = 50.0, 22 030 measured reflections, 7965 independent
reflections (Rint = 0.0419), 414 refined parameters, GOF = 1.090,
R1 = 0.0556 and wR2 = 0.1237 [I > 2r(I)], R1 = 0.0721 and
8.58 (dd, JPH = 12 Hz, JHH = 11 Hz, 1H); 13C{1H} NMR (75 MHz,
C6D6, 298 K) d 0.7 (CH3), 1.0 (CH3), 1.4 (CH3), 1.6 (CH3), 1.8 (CH3),
28.8 (CH2), 28.9 (d, J = 4 Hz, CH3), 30.2 (CH), 31.1 (CH), 32.0 (CH),
34.3 (d, J = 4 Hz, CH), 48.1 (s, CH), 82.3 (d, J = 16 Hz, CH), 109.6 (s,
CH), 122.6 (CH), 126.8 (CH), 145.8 (C), 150.9 (C), 156.3 (d,
J = 31 Hz, CH), 173.2 (d, J = 23 Hz, C); 31P{1H} NMR (120 MHz,
C6D6, 298 K) d 121. High-resolution MS (FAB) Calc. for C39H76OSi6-
P193Ir 952.3879. Found: 952.3857 ([M]+).
wR2 = 0.1326 [for all data], largest difference in peak and hole
2
3
0.782 and ꢀ0.273 e Åꢀ3
.
Crystal data for [4aꢁ(OEt2)]2ꢁ(0.5hexane): C41H89LiO2PSi7,
M = 848.66, T = 103(2) K, monoclinic, P21/a (no. 14), a =
25.4620(4) Å, b = 12.3405(2) Å, c = 36.7695(6) Å, b = 107.1418(7)°,
V = 11040.3(3) Å3, Z = 8, Dcalc = 1.021 g cmꢀ3
, l ,
= 0.230 mmꢀ1
2hmax = 50.0, 92 054 measured reflections, 19 339 independent
reflections (Rint = 0.0705), 987 refined parameters, GOF = 1.091,

T. Matsumoto et al. / Journal of Organometallic Chemistry 695 (2010) 1019–1025
[7] (a) N. Tokitoh, Y. Arai, R. Okazaki, S. Nagase, Science 277 (1999) 78;
1025
R1 = 0.0667 and wR2 = 0.1635 [I > 2r(I)], R1 = 0.0998 and wR2 =
(b) N. Tokitoh, Y. Arai, T. Sasamori, R. Okazaki, S. Nagase, H. Uekusa, Y. Ohashi,
J. Am. Chem. Soc. 120 (1998) 433;
(c) T. Sasamori, Y. Arai, N. Takeda, R. Okazaki, Y. Furukawa, M. Kimura, S.
Nagase, N. Tokitoh, Bull. Chem. Soc. Jpn. 75 (2005) 661;
(d) T. Sasamori, N. Takeda, M. Fujio, M. Kimura, S. Nagase, N. Tokitoh, Angew.
Chem., Int. Ed. 41 (2002) 139;
(e) T. Sasamori, N. Takeda, N. Tokitoh, Chem. Commun. (2000) 1353;
(f) T. Sasamori, N. Takeda, N. Tokitoh, J. Phys. Org. Chem. 16 (2003) 450;
(g) N. Nagahora, T. Sasamori, N. Takeda, N. Tokitoh, Chem. Eur. J. 10 (2004)
6146;
0.1896 [for all data], largest difference in peak and hole 0.875
and ꢀ0.671 e Åꢀ3
.
Crystal data for 7: C25H36NORh, M = 469.46, T = 103(2) K, mono-
clinic, C2/c (no. 15), a = 8.8811(2) Å, b = 8.8115(2) Å, c = 15.1061(3)
Å,
a
= 90.6294(9)°, b = 101.8877(10)°,
c = 107.159(2)°, V = 1102.04(4)
Å3, Z = 2, Dcalc = 1.415 g cmꢀ3
,
l
= 0.790 mmꢀ1, 2hmax = 51.0, 9717
measured reflections, 4057 independent reflections (Rint = 0.0308),
259 refined parameters, GOF = 1.167, R1 = 0.0237 and wR2 = 0.0600
(h) T. Sasamori, E. Mieda, N. Nagahora, N. Takeda, N. Takagi, S. Nagase, N.
Tokitoh, Chem. Lett. 34 (2005) 166;
[I > 2r(I)], R1 = 0. 0252 and wR2 = 0.0607 [for all data], largest dif-
ference in peak and hole 0.379 and ꢀ0.653 e Åꢀ3
.
(i) T. Sasamori, A. Tsurusaki, N. Nagahora, K. Matsuda, Y. Kanemitsu, Y.
Watanabe, Y. Furukawa, N. Tokitoh, Chem. Lett. 35 (2006) 1382;
(j) N. Nagahora, T. Sasamori, N. Tokitoh, Chem. Lett. 35 (2006) 220;
(k) T. Sasamori, E. Mieda, N. Nagahora, K. Sato, D. Shiomi, T. Takui, Y. Hosoi, Y.
Furukawa, N. Takagi, S. Nagase, N. Tokitoh, J. Am. Chem. Soc. 128 (2006) 12582.
[8] (a) H. Hamaki, N. Takeda, N. Tokitoh, Inorg. Chem. 46 (2007) 1795;
(b) H. Hamaki, N. Takeda, T. Yamasaki, T. Sasamori, N. Tokitoh, J. Organomet.
Chem. 692 (2007) 44;
(c) H. Hamaki, N. Takeda, N. Tokitoh, Organometallics 25 (2006) 2457;
(d) N. Takeda, H. Hamaki, N. Tokitoh, Chem. Lett. 33 (2004) 134.
[9] (a) Although there has been a few reports on the theoretical calculations for a
phosphorus analogue of a Schiff-base ligand from the viewpoint of catalytic
activities, no example of such a unique ligand has been synthesized so far. See
M.S.W. Chan, L.Q. Deng, T. Ziegler, Organometallics 19 (2000) 2741;
(b) T.Z. Zhang, D.W. Guo, S.Y. Jie, W.H. Sun, T. Li, X.Z. Yang, J. Polym. Sci. Polym.
Chem. 42 (2004) 4765.
[10] The intermediacy of a b-iminophosphenato complex, which is a phosphorus
analogue of a b-diketiminato complex, was proposed to be generated; see F.
Basuli, J. Tomaszewski, J.C. Huffman, D.J. Mindiola, J. Am. Chem. Soc. 125
(2003) 10170.
[11] T. Sasamori, T. Matsumoto, N. Tokitoh, Organometallics 26 (2007) 3621.
[12] (a) N. Tokitoh, T. Matsumoto, T. Sasamori, Heterocycles 76 (2008) 981;
(b) T. Sasamori, T. Matsumoto, N. Tokitoh, Polyhedron, in press, doi:10.1016/
j.poly.2009.06.043.
[13] A.M. Arif, J.E. Boggs, A.H. Cowley, J.-G. Lee, M. Pakulski, J.M. Power, J. Am.
Chem. Soc. 108 (1986) 6083.
[14] The 1,2-addition reaction of a silylphosphine with an activated alkyne has
been reported, see M. Reisser, A. Maier, G. Maas, Synlett 9 (2002) 1459.
[15] R.C. Yu, C.H. Hung, J.H. Huang, H.Y. Lee, J.T. Chen, Inorg. Chem. 41 (2002) 6450.
[16] E. Urnèzius, J.K. Stephen, J.D. Protasiewicz, Inorg. Chim. Acta 297 (2000) 181.
[17] (a) A.J. Naaktgeboren, R.J.M. Nolte, W. Drenth, J. Am. Chem. Soc. 102 (1980)
3350;
(b) I. Lee, F. Dahan, A. Maisonnat, R. Poilblanc, Organometallics 13 (1994)
2743.
[18] A.B. Pangborn, M.A. Giardello, R.H. Grubbs, R.K. Rosen, F.J. Timmers,
Organometallics 15 (1996) 1518.
6. Theoretical calculations
All calculations were conducted using the GAUSSIAN 03 series of
electronic structure programs [22]. The geometries were optimized
with density functional theory at the B3LYP level using 6-31G(d)
basis sets (for C, H, N, and O), 6-31G(3d) (for P and Si), and Lanl2DZ
(for Rh). It was confirmed by frequency calculations that the opti-
mized structures have minimum energies.
7. Supplementary material
CCDC 729128, 729129, 729130 and 729131 contain the supple-
mentary crystallographic data for 2b, 3a, [4aꢁ(OEt2)]2ꢁ(0.5hexane)
and 7. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Acknowledgements
This work was supported by Grant-in-Aid for Creative Scientific
Research (No. 17GS0207), Science Research on Priority Areas (No.
20036024, ‘‘Synergy of Elements”), and the Global COE Program
(‘‘Integrated Materials Science”, Kyoto University) from the Minis-
try of Education, Culture, Sports, Science and Technology, Japan.
ˇ
[19] N. Nagahora, T. Sasamori, N. Takeda, N. Tokitoh, Organometallics 24 (2005)
3074.
References
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