Synthesis, structure, and reactivity of novel iron(II) complexes with a five-membered chelate ligand κ2(Si,N)- SiMe2O(2-C5H4N)

Article abstract of DOI:10.1016/S0022-328X(03)00043-3

Photolysis of Cp′(CO)₂FeSiMe₂O (2-C₅H₄N) (1a: Cp′ = η⁵- C₅H₅ (Cp), 1b: Cp′ = η⁵-C₅Me₅ (Cp*)) afforded Cp′(CO)Fe[κ² (Si,N)-SiMe₂O(2-C₅H₄N)] (2a: Cp′ = Cp, 2b: Cp′ = Cp*) in good yield each. These cyclic compounds also formed in moderate yields through photoreaction of Cp′ (CO)₂FeSiMe₃ with HSiMe₂O(2-C₅H₄N) (3). Single-crystal X-ray diffraction study confirmed the structure of 2b containing a five-membered chelate ring comprised of Fe, Si, O, C, and N. Complexes 2a and 2b were thermally stable and did not react with slight excess of PR₃ (R = Me, Ph) in benzene-d₆ solution below 80 °C. Above 80 °C, 2a reacted slowly with PR₃ to give Cp(CO)(PR₃)FeSiMe₂O (2-C₅H₄N) (6: R = Me, 7: R = Ph) accompanied by the cleavage of the Fe-N bond. These results indicate that both Fe-Si bond and Fe-N bond in 2 are notably sturdy.

Full text of DOI:10.1016/S0022-328X(03)00043-3

Journal of Organometallic Chemistry 669 (2003) 189ꢁ199
/
www.elsevier.com/locate/jorganchem
Synthesis, structure, and reactivity of novel iron(II) complexes with a
five-membered chelate ligand k2(Si,N)-SiMe2O(2-C5H4N)
Takahiro Sato a, Masaaki Okazaki a, Hiromi Tobita a,*, Hiroshi Ogino b
a Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
b Miyagi Study Center, The University of the Air, Sendai 980-8577, Japan
Received 18 September 2002; received in revised form 15 January 2003; accepted 16 January 2003
Abstract
Photolysis of Cp?(CO)2FeSiMe2O(2-C5H4N) (1a: Cp?ꢀ
/
h5-C5H5 (Cp), 1b: Cp?ꢀh5-C5Me5 (Cp*)) afforded Cp?(CO)Fe[k2(Si,N)-
/
SiMe2O(2-C5H4N)] (2a: Cp?ꢀCp, 2b: Cp?ꢀCp*) in good yield each. These cyclic compounds also formed in moderate yields
/
/
through photoreaction of Cp?(CO)2FeSiMe3 with HSiMe2O(2-C5H4N) (3). Single-crystal X-ray diffraction study confirmed the
structure of 2b containing a five-membered chelate ring comprised of Fe, Si, O, C, and N. Complexes 2a and 2b were thermally
stable and did not react with slight excess of PR3 (Rꢀ
with PR3 to give Cp(CO)(PR3)FeSiMe2O(2-C5H4N) (6: Rꢀ
N bond in 2 are notably sturdy.
/
Me, Ph) in benzene-d6 solution below 80 8C. Above 80 8C, 2a reacted slowly
/
Me, 7: RꢀPh) accompanied by the cleavage of the FeꢀN bond. These
/
/
results indicate that both Feꢀ
/
Si bond and Feꢀ
/
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Silyl complexes; Iron complexes; Chelate; Photolysis; X-ray structure analysis
1. Introduction
idium(I)
complex
Ir[k2(Si,P)-Me2Si(CH2)2PPh2]-
(PMe3)3 catalyzes the isomerization of HPhMeSiSiMe3
to HMe2SiSiMe2Ph [3c]. The coordinatively unsaturated
square-planar silylrhodium(I) complex Rh[k2(Si,P)-
Me2Si(CH2)2PPh2](PMe3)2 can be isolated and causes
dehydrogenative coupling of a monohydrosilane to give
a disilane [3e]. These reactions occur under mild
Over the last few decades, the synthesis and reactivity
of transition metal silyl complexes have received sig-
nificant attention, since these complexes are assumed to
be key intermediates in the various metal-mediated
transformation reactions of organosilicon compounds
[1]. Efforts in this area revealed that silyl ligands have an
exceptionally strong s-donating and trans-influencing
ability. Taking account of these characters, silyl ligands
are also expected to exhibit strong trans-effect. There-
fore, our recent studies have focused on the utilization
of silyl groups as ancillary ligands to greatly accelerate
the generation of highly reactive, unsaturated metal
conditions (25ꢁ45 8C), which might be attributable to
/
the strong s-donating ability and trans-effect of silyl
ligands.
On the other hand, there are only a few examples of
Si- and N-coordinated bidentate ligands. It is well
known that amine ligands are good s-donors but are
poor p-acceptors compared with phosphine ligands.
Thus, complexation of silicon and nitrogen atoms with
a metal could generate a more electron-rich metal center
than that of silicon and phosphorus atoms. The com-
centers. To avoid the cleavage of the metalꢁsilicon
/
bonds, the Si,P chelate-type ligands k2(Si,P)-
?
R2Si(CH2)2PR2 have been developed [2,3]. In complexes
plexes M[k2(Si,N)-SiMe2(8-quinolyl)]3 (Mꢀ
/
Rh, Ir) and
containing these ligands, loss of the silyl group from the
metal center is effectively retarded and we were able to
find some interesting reactivities of them: The silylir-
Cp2Ti[k2(Si,N)-SiMe2(2-C5H4N)] were synthesized and
characterized by X-ray crystal structure analysis [4,5],
but little has been known about their reactivity. Harrod
et al. reported that the pyridine part in Cp2Ti[k2(Si,N)-
SiMe2(2-C5H4N)] was labile and was reversibly replaced
by two-electron donor ligands such as PMe3 and
* Corresponding author. Fax: ꢂ
/
81-22-217-6543.
E-mail address: tobita@inorg.chem.tohoku.ac.jp (H. Tobita).
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00043-3

190
T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ199
/
pyridine [5]. More recently, Tilley et al. successfully
synthesized a complex containing an NSiN tridentate
ligand, Ir(H)(Cl)(cyclooctene)[k3(Si,N,N)-SiMe(8-qui-
nolyl)2], in which the Ir(NSiN) fragment is chemically
robust [6].
We encountered the formation of a novel iron
complex Cp*(CO)Fe[k2(Si,N)-SiMe2O(2-C5H4N)] dur-
ing research on the thermal- and photochemical reac-
tions of Cp*(CO)Fe(H){SiMe2O(2-C5H4N)}2 [7]. This
finding prompted us to start examining the utility of the
Si,N chelate ligand. This paper describes the synthesis,
structure, and reactivity of iron complexes having the
five-membered chelate ligand k2(Si,N)-SiMe2O(2-
C5H4N).
Fig. 2. ORTEP drawing of 1b with 50% thermal ellipsoids.
Table 1
Selected bond lengths (A) and angles (8) for complexes 1b and 2b
˚
2. Results and discussion
1b
2b
Bond lengths
FeꢀSi
Siꢀ
Siꢀ
Siꢀ
2.1. Synthesis of (2-pyridyloxy)silyl complexes (1a and
1b)
/
2.2990(6)
1.871(2)
1.875(2)
1.7070(14)
1.347(2)
1.315(2)
1.385(3)
1.372(3)
1.368(3)
1.360(3)
1.340(3)
1.743(2)
1.738(2)
3.8266(18)
1.143(2)
1.145(2)
2.2640(10)
1.873(4)
1.874(4)
1.743(3)
1.320(4)
1.341(4)
1.401(5)
1.357(6)
1.373(6)
1.355(5)
1.359(4)
/
C(1)
C(2)
O(1)
/
Treatment of Cp?(CO)2FeSiMe2Cl (4a: Cp?ꢀ
/Cp, 4b:
/
Cp?ꢀCp*) with an equimolar amount of NaO(2-
/
O(1)ꢀ
N(1)ꢀ
C(3)ꢀ
C(4)ꢀ
C(5)ꢀ
C(6)ꢀ
C(7)ꢀ
/
C(3)
/
C(3)
C(4)
C(5)
C(6)
C(7)
N
C5H4N) in refluxing acetonitrile gave 1a and 1b in 63
and 91%, respectively (Eq. (1)). The elemental analysis
and mass spectral data supported the molecular formula
of each complex.
/
/
/
/
/
Feꢀ
Feꢀ
Feꢀ
/
C(8)
C(9)
N
1.720(4)
a
/
b
/
1.999(3)
C(8)ꢀ
/O(2)
1.160(4)
a
C(9)ꢀ/O(3)
Bond angles
Feꢀ
Feꢀ
Feꢀ
C(1)ꢀ
SiꢀO(1)ꢀ
O(1)ꢀC(3)ꢀ
O(1)ꢀC(3)ꢀ
C(3)ꢀC(4)ꢀ
C(4)ꢀC(5)ꢀ
C(5)ꢀC(6)ꢀ
C(6)ꢀC(7)ꢀ
C(7)ꢀNꢀ
FeꢀC(8)ꢀ
FeꢀC(9)ꢀ
Feꢀ
SiꢀFeꢀ
SiꢀFeꢀ
SiꢀFeꢀ
C(8)ꢀ
C(8)ꢀ
/
Siꢀ
Siꢀ
Siꢀ
/
O(1)
C(1)
C(2)
117.98(6)
114.75(9)
112.49(8)
105.27(13)
125.34(12)
117.33(16)
119.07(17)
118.11(19)
119.3(2)
98.36(9)
118.41(14)
129.10(16)
102.7(2)
116.7(2)
117.9(3)
120.8(4)
120.1(4)
118.7(4)
119.3(4)
123.5(4)
117.1(3)
ð1Þ
/
/
/
/
However, the tautomerism between 2-hydroxypyri-
dine and 2-pyridone has been well known [8], so that we
had to consider another possible structure for 1, i.e. the
keto-form depicted in Fig. 1.
To determine which structure 1 adopts, we carried out
an X-ray crystal structure analysis of 1b. The ORTEP
drawing is shown in Fig. 2 and selected bond lengths
and angles are listed in Table 1.
/
Siꢀ
/C(2)
/
/
C(3)
/
/N
/
/C(4)
/
/
C(5)
C(6)
C(7)
N
/
/
/
/
118.2(2)
/
/
124.2(2)
/
/C(3)
116.62(18)
174.7(2)
Complex 1b proved to take the enol-form with an Feꢀ
/
/
/
O(2)
O(3)
175.9(3)
a
/
/
178.0(2)
Siꢀ
/
O(1)ꢀ
/
C(3)ꢀ
/
N linkage at least in the solid state. The
˚
interatomic distance between Fe and N is 3.8266(18) A,
/
Nꢀ
/
C(7)
C(8)
C(9)
N
121.5(2)
86.89(12)
/
/
87.99(7)
83.51(7)
indicating no bonding interaction between them. The
˚
Si bond length (2.2990(6) A) is one of the shortest
a
/
/
Feꢀ
/
/
/
81.00(8)
a
/
Feꢀ
/
C(9)
N
95.10(10)
/
Feꢀ
/
96.36(14)
a
C(9) of 1b is in a carbonyl ligand, while C(9) of 2b is in the Cp*
ligand. The data for the latter are intentionally omitted to avoid
confusion.
b
This is the interatomic distance between Fe and N.
Fig. 1. Keto-forms of 1a (Rꢀ
/
H) and 1b (RꢀMe).
/

T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ
/199
191
among those known for dimethylsilyliron complexes
˚
(2.30ꢁ
/
2.46 A) [9]. On the other hand, the Siꢀ
/
O bond
˚
length in 1b (1.7070(14) A) is longer than those in the
˚
normal alkoxysilanes (1.58ꢁ1.65 A) [10]. These structur-
/
al features are attributable to the electron-withdrawing
effect of a 2-pyridyloxy group on the silicon atom. Thus,
when an electron-withdrawing group is attached to
silicon, the strong p-interaction between M(dp) and
ð3Þ
The mechanism of the exchange of silyl groups
between hydrosilane and Cp?(CO)2FeSiR3 has been
thoroughly investigated by various groups [13]. Based
on their studies, we propose the formation mechanism
of 2 described in Scheme 1.
SiX(s*) (Xꢀ
which makes the Mꢀ
and longer, respectively.
/
the electron-withdrawing group) arises,
/
Si and SiꢀX bond lengths shorter
/
The spectroscopic features of 1 also support that 1
takes the enol-form in solution. Thus, the IR spectra of
1a and 1b in hexane solution as well as in the solid state
It consists of four paths; (i) photo-induced elimination
of one CO ligand, (ii) Hꢀ
/
Si oxidative addition of
exhibit no Cꢁ
/
O stretching bands characteristic of the
keto-form. In the 13C-NMR spectra of 1a and 1b, the
chemical shift of one of the pyridine ring carbon falls in
hydrosilane 3 to give a hydridobis(silyl)iron (IV) com-
plex A, (iii) reductive elimination of trimethylsilane, and
(iv) coordination of the pyridyl nitrogen to the metal
center. The intermediate Cp(CO)Fe(H)(SiMe3){Si-
Me2O(2-C5H4N)} (A) was not detected spectroscopi-
cally, probably due to the facile reductive elimination of
either HSiMe3 or HSiMe2O(2-C5H4N) (3) [7,13].
the range 147ꢁ148 ppm, which is characteristic of the a-
/
CH carbon in alkoxypyridines (the enol-form) and are
out of the range for N-alkylpyridones (the keto-form,
140ꢁ141 ppm) [11]. Furthermore, Cragg et al. have
/
Each IR spectrum of 2a and 2b shows only one
intense band in the terminal CO region (2a: 1884 cmꢃ1
shown that the trimethylsilyl derivative of 2-pyridone,
which is closely related to 1, exists only in enol-form in
solution [12].
,
2b: 1886 cmꢃ1 in KBr pellet), in accord with the
1
In the 29Si-NMR spectra, the signals appear at 71.9
ppm (1a) and 72.5 ppm (1b), which can be assigned to
the silicon atoms directly bound to iron.
structure having only one CO ligand. In the H- and
13C-NMR spectra, the two Me groups on Si are
chemically equivalent in 1 but inequivalent in 2, which
is consistent with the formation of a chelate ring
containing a chiral Fe atom. In the 29Si-NMR spectra,
the signals of 2 are substantially downfield shifted (113.5
ppm (2a), 114.4 ppm (2b)) compared with those of 1
(71.9 ppm (1a), 72.5 ppm (1b)). The 29Si signals of
donor-stabilized dimethylsilyleneiron complexes usually
2.2. Synthesis of complexes 2a and 2b having a
k2(Si,N)-SiMe2O(2-C5H4N) ligand
Photoreactions of 1a and 1b in C6D6 solution were
1
carried out and monitored by H-NMR spectroscopy.
appear in the region of 92ꢁ127 ppm [14]. Thus, there
/
seems to be a significant contribution from a donor-
stabilized silylene complex form (II) in the bonding
mode of 2 (Fig. 3).
The reactions proceeded cleanly to give 2a and 2b with
evolution of CO gas (Eq. (2)). Irradiation of 1a and 1b in
large scale and subsequent work-up of the resulting
solution afforded red crystals of 2a and 2b in 48 and
68% yields, respectively. These complexes are more air-
sensitive than the corresponding silyl complexes 1a and
1b. Complexes 2 are the first example of a Group 8
metal complex having a k2(Si,N)-ligand.
2.3. Crystal structure of 2b
An ORTEP drawing of 2b is shown in Fig. 4. Selected
bond lengths and angles are listed in Table 1. The
molecule contains a five-membered chelate ring which
consists of Fe, Si, O(1), C(3), and N. A couple of
enantiomers, based on a chiral iron center, makes a
racemic body in the unit cell. The Feꢀ
/
Si bond length in
˚
2b (2.2640(10) A) is considerably shorter than that in 1b
˚
(2.2990(6) A) and comparable to those in the donor-
˚
stabilized silyleneiron complexes (2.20ꢁ
This suggests that the Feꢀ
significant unsaturated bond character. On the other
/
2.29 A) [14].
/
Si bond of 2b bears a
ð2Þ
˚
O(1) distance in 2b (1.743(3) A) is longer
hand, the Siꢀ
/
Complexes 2 were also synthesized by irradiation of
Cp?(CO)2FeSiMe3 and HSiMe2O(2-C5H4N) (3) in hex-
ane in moderate yields (Eq. (3)).
˚
than those in 1b (1.7070(14) A) and the normal
˚
alkoxysilanes (1.58ꢁ
bond character of Siꢀ
/
1.65 A) [10], indicating the dative
O(1). These structural features
/

192
T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ199
/
Scheme 1. A plausible mechanism for formation of 2 from 5.
of the form II is partly because the coordination of N to
Fe makes the metal center more electron-rich, which
then enhances the back-donation from Fe(dp) to Siꢀ
/
O(s*) in comparison with 1a and 1b.
˚
N bond (1.999(3) A) in 2b is shorter than that
˚
in the pyridine iron complexes (2.22 A in average) [15].
Although, to our knowledge, there is no X-ray char-
The Feꢀ
/
Fig. 3. Two important canonical forms for 2a (Rꢀ
/
H) and 2b (Rꢀ
/
Me). (I) Silyl complex form; (II) silylene complex form (dative bonds
are emphasized).
acterized amidoiron complex, the Feꢀ
/
N bond length of
2b is likely to be a mean value between dative and
covalent bonds.
further support the consideration that the bonding
mode of 2b is significantly contributed by the silylene
complex form (keto-form) II in Fig. 3. To estimate the s-
character of the silicon atom in donor-stabilized silylene
ligands, the sum of three bond angles around silicon is
often used [14]. Ideally, it becomes 3608 for sp2-
hybridized silicon atom and 3288 for sp3-hybridized
one. In 2b, the sum of the three bond angles around
The distance of the C(3)ꢀ
/
O(1) bond in the chelate ring
˚
of 2b (1.320(4) A) is nearly equal to that of 1b (1.347(2)
˚
A), and also those of 2-methoxypyridines {e.g. 2-
˚
methoxy-3,5-dinitropyridine (1.312(5) A) [16] and Co-
˚
(MeO(2-C5H4N))2Cl2 (1.350(6) and 1.344(6) A) [17]}
and to that of bridged h2-2-pyridonato ligands in Ru2(m-
O(2-C5H4N))2(CO)4(HO(2-C5H4N)2) (1.305(3) and
˚
1.301(3) A) [18]. In addition, these are distinctly longer
silicon, i.e. Feꢀ
/
Siꢀ
/
C(1), Feꢀ
/
Siꢀ
/
C(2), and C(1)ꢀ
/
Siꢀ
/
˚
O bond length of 2-pyridone (1.251(1) A)
C(2), is 350.2(5)8, that is much larger than those in
usual silyl complexes (e.g. 1b, 332.5(3)8). This also
indicates that the silicon atom in 2b is significantly
contributed by sp2-hybridization. The large contribution
than the Cꢁ
/
[19]. Therefore, a single line is appropriate to draw the
CꢀO bond next to the pyridine ring in 2b.
For 2, an isomer having an FeꢀSiꢀO three-membered
/
/
/
chelate ring illustrated in Fig. 5 is conceivable, but
formation of such an isomer was not confirmed by
NMR spectroscopy. This is attributable to the ring
strain of the three-membered ring and the low affinity of
oxygen toward Fe in 2.
2.4. Reactivity of the Fe[k2(Si,N)-SiMe2O(2-C5H4N)]
chelate in 2
Complexes 2a and 2b are air-sensitive but thermally
stable. The reactivity of 2a under various reaction
Fig. 5. A possible isomer of 2 (Rꢀ
membered ring.
/
H, Me) having an Feꢀ
/
SiꢀO three-
/
Fig. 4. ORTEP drawing of 2b with 50% thermal ellipsoids.

T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ
/199
193
conditions is summarized in Table 2. Heating a benzene-
d6 solution of 2 in a sealed tube did not lead to
decomposition even after 1 week at 90 8C.
ligand.
Lability of the pyridine part in the chelate ligand
[k2(Si,N)-SiMe2O(2-C5H4N)] of 2 was examined using
tertiary phosphines as reactants. It is well known that
ƒ
coordination of PR3 to an unsaturated Cp?(CO)FeSiR3
ƒ
species affords Cp?(CO)(PR3)FeSiR3 [20]. Therefore, if
the FeꢀN bond cleaves in the presence of PR3,
ð4Þ
/
Complex 2a is stable in the presence of MeOH below
80 8C. On the other hand, when 2a was treated with a
MeOH solution of NaOMe in the presence of PPh3, the
reaction completed within 1 h at room temperature to
give Cp(CO)(PPh3)FeH (8) [24] and SiMe2(OMe)2,
quantitatively. This reaction would begin with the
coordination of PR3 will occur. Complexes 2a and 2b
actually did not react with PMe3 and PPh3 at room
temperature. Heating the benzene-d6 solution of 2a in
the presence of 1.5 equivalents of PMe3 at 80 8C also did
not show any change in the 1H-NMR spectrum.
However, upon heating this solution at 100 8C for 3
days, 60% of 2a was converted to a phosphine-coordi-
nated product 6 with formation of a small amount of
unidentified products (Eq. (4)). Complex 6 was char-
acterized by the NMR spectral data. In the 29Si-NMR
spectrum of the reaction mixture, a new doublet signal
cleavage of the Feꢀ/Si bond, which is caused by the
nucleophilic attack of methoxide onto silicon, as illu-
strated in Scheme 2. Another mechanism, a reaction
beginning with replacement of the pyridine part of 2a by
PPh3 or MeOH, is strongly refuted with regard to the
poor reactivity of 2a toward MeOH in the presence of
PPh3 without NaOMe. Formation of MeOSiMe2O(2-
C5H4N) (9) was expected in Scheme 2 but was not
confirmed spectroscopically. The compound would
subsequently be converted to SiMe2(OMe)2 through
the nucleophilic substitution of an O(2-C5H4N) group
by a MeO group of MeOH. Actually, an authentic
sample of 9 was found to react with a mixture of MeOH
appeared at 79.7 ppm (2JPSi
ꢀ44 Hz). The coupling
/
constant is comparable to that in Cp(CO)(PPh3)Fe-
SiMe3 (30 Hz) [21] and Cp(PPh2CH2CH2PPh2)FeSiMe3
(46 Hz) [21], which strongly supports the formation of 6.
In the 31P-NMR spectrum, a new signal appeared at
33.6 ppm. The chemical shift is characteristic of PMe3
coordinated to Fe, e.g. Cp*(CO)(PMe3)FeMe (36.0
ppm) [22] and Cp(PMe3)2FeSiH3 (32.5 ppm) [23]. The
reaction of 2a with 1.5 equivalents of PPh3 proceeded
more slowly to convert ca. 10% of 2a, after 3 days at
100 8C, into a PPh3-coordinated product 7 (Eq. (4)).
Further thermal reaction at higher temperatures led to
decomposition of both 2a and 7. Complex 2b is less
reactive toward PPh3 than 2a. Thus, the benzene-d6
solution of 2b with five equivalents of PPh3 did not
change after 7 days at 150 8C. The lack of reactivity of
2b may be ascribed to the steric protection by the Cp*
and small amount of NaOMe rapidly (B10 min at
/
room temperature) to give SiMe2(OMe)2.
2.5. Conclusion
We successfully synthesized iron complexes 2a and 2b
with the novel five-membered chelate ligand k2(Si,N)-
SiMe2O(2-C5H4N), in which coordination of the pyri-
dine nitrogen atom is quite strong and inert to substitu-
tion (up to 80 8C). Above 80 8C, the ironꢁ
in 2a started to cleave and phosphine-substituted
products 6 and 7 were formed. Cleavage of the ironꢁ
/
nitrogen bond
Table 2
Reactivity of 2a in the presence of reactants
a
/
silicon bond in 2a occurred easily by the direct
nucleophilic attack of NaOMe onto the silicon,
although a weaker nucleophile MeOH did not react
with 2a at room temperature. Employment of complexes
containing the Si,N-chelate ligand to catalysis is under
investigation.
Reactant (molar ratio Temperature and
vs. 2a)
Reactivity (conversion
ratio of 2a)
time
None
PMe3 (1.5)
90 8C, 7 days
80 8C, 5 h
Non-reactive
Non-reactive
100 8C, 3 days
80 8C, 5 h
Reactive (60%)
Non-reactive
PPh3 (1.5)
100 8C, 7 days
80 8C, 5 h
80 8C, 5 h
Poorly reactive (13%)
Non-reactive
Non-reactive
MeOH (1.3)
MeOH (1.3)ꢂ
/PPh3
3. Experimental
(1.5)
MeOH (9)ꢂ
/
PPh3 (3)
Room temperature, Poorly reactive (3%)
24 h
3.1. General comments
MeOH (9)ꢂPPh3 (3)ꢂ
/
/
Room temperature, Highly reactive (100%)
NaOMe (0.7)
B1 h
/
All reactions and manipulations were carried out
using high-vacuum line techniques, standard Schlenk
techniques, or in a glovebox under an atmosphere of N2.
a
0.06ꢁ
0.09 mol lꢃ1 benzene-d6 solution, in a vacuum-sealed glass
/
tube.

194
T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ199
/
Scheme 2. A possible mechanism for the reaction of 2a with MeOHꢂ
/
NaOMeꢂPPh3.
/
The compounds Cp(CO)2FeSiMe2Cl (4a) [25],
Cp*(CO)2FeSiMe2Cl (4b) [26], Cp(CO)2FeSiMe3 (5a)
[20a], Cp*(CO)2FeSiMe3 (5b) [20b], Cp*(CO)2FeMe
(10) [27], and MeOSiMe2Cl [28] were synthesized
according to published methods. Acetonitrile (CaH2),
chlorodimethylsilane (CaH2), Et3N (Na), ether (Na-
benzophenone-ketyl), hexane (Na-benzophenone-ketyl),
MeOH (Mg(OMe)2), THF (Na-benzophenone-ketyl),
and benzene-d6 (K mirror) were distilled from the drying
agents indicated in parentheses. Hexamethylbenzene
and 2-hydroxypyridine were sublimed before use. So-
dium hydride in oil was repeatedly washed with hexane,
and used immediately after it was dried. PPh3 was
recrystallized from EtOH and dried under vacuum prior
to use. PMe3 was purchased from Aldrich, and used as
mmol) in refluxing Et3N (30 ml). After 2 h, it was
allowed to cool to room temperature (r.t.) and the
solvent was removed under reduced pressure. The
residue was extracted with three 5 ml portions of hexane
and the insoluble materials were filtered off with a D3
sintered glass filter and washed with additional three 5
ml portions of hexane. All solvents were removed under
reduced pressure. The reddish brown residue was
crystallized from hexane at ꢃ
/
75 8C to afford 1a (415
brown crystals.
M.p.: 37 8C. H-NMR (C6D6): d 0.97 (s, 6H, SiMe2),
4.15 (s, 5H, C5H5), 6.42 (ddd, 1H, Jꢀ7.1, 5.1, 0.8 Hz,
OC5H4N), 6.62 (dd, 1H, Jꢀ8.2, 0.8 Hz, OC5H4N), 7.03
(ddd, 1H, Jꢀ8.2, 7.1, 2.1 Hz, OC5H4N), 8.12 (dd, 1H,
Jꢀ
5.1, 2.1 Hz, OC5H4N). 13C{1H}-NMR (C6D6): d 9.8
mg, 1.26 mmol, 63%) as yellowishꢁ
/
1
/
/
/
/
1
received. H-, 13C-, 29Si-, and 31P-NMR spectra were
(SiMe2), 83.7 (C5H5), 113.5, 116.6, 138.8, 147.5, 163.6
(pyridine ring), 215.3 (FeCO).
recorded on a Bruker ARX-300 spectrometer at 300,
1
75.5, 59.6, and 121.5 MHz, respectively. H-, 13C-, and
29Si-NMR spectra were referenced to SiMe4. 31P-NMR
spectra were referenced to 85% H3PO4. IR spectra were
run on a Horiba FT-200 or Horiba FT-730 spectrometer
as either solids (KBr pellet) or neat liquid (NaCl plate).
3.3. Synthesis of Cp*(CO)2FeSiMe2O(2-C5H4N) (1b)
Complex 1b (725 mg, 1.82 mmol) was synthesized in
91% yield by a procedure analogous to that for 1a, using
4b (680 mg, 2.00 mmol) and NaO(2-C5H4N) (263 mg,
UVꢁvis absorption spectra were measured on a Shi-
/
madzu Multispec 1500 spectrometer. Mass spectra (EI,
70 eV) were obtained on a Shimadzu GCMS QP-5050 or
a Hitachi M-2500S spectrometer. Irradiation was car-
ried out with an Ushio UV-450 450 W medium-pressure
Hg lamp placed in a water-cooled quartz jacket. Sample
solutions were irradiated in Pyrex tubes.
2.25 mmol). Recrystallization from hexane at ꢃ30 8C
/
gave yellow crystals of 1b. M.p.: 69 8C. 1H-NMR
(C6D6): d 1.04 (s, 6H, SiMe2), 1.51 (s, 15H, C5Me5),
6.43 (ddd, 1H, Jꢀ
1H, Jꢀ8.2, 0.6 Hz, OC5H4N), 7.08 (ddd, 1H, Jꢀ
5.0, 2.0 Hz,
/
7.2, 5.0, 0.6 Hz, OC5H4N), 6.63 (dd,
/
/8.2,
7.2, 2.0 Hz, OC5H4N), 8.19 (dd, 1H, Jꢀ
/
OC5H4N). 13C{1H}-NMR (C6D6): d 8.7 (SiMe2), 9.6
(C5Me5), 95.2 (C5Me5), 113.2, 116.2, 138.5, 147.8, 163.9
(pyridine ring), 217.3 (FeCO).
Elemental analysis and mass spectroscopic data for
isolated compounds are listed in Table 3. The 29Si-, 31P-
NMR, IR, and UVꢁvis spectroscopic data of new
/
compounds are listed in Table 4.
3.4. Synthesis of HSiMe2O(2-C5H4N) (3)
3.2. Synthesis of Cp(CO)2FeSiMe2O(2-C5H4N) (1a)
A 300 ml three-necked flask equipped with a pressure-
equalized dropping funnel, an ice-cooled condenser, and
a magnetic stirring bar was charged with a solution of
chlorodimethylsilane (5.46 g, 57.8 mmol, 1.15 equiva-
lents) and Et3N (5.85 g, 57.7 mmol, 1.15 equivalents) in
60 ml of THF. To it was added dropwise a solution of 2-
NaO(2-C5H4N) was prepared by treatment of equi-
molar amounts of sodium hydride and 2-hydroxypyr-
idine in refluxing ether, dried under vacuum, and stored
under N2. Complex 4a (542 mg, 2.00 mmol) was treated
with the above-mentioned NaO(2-C5H4N) (255 mg, 2.18

T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ
/199
195
Table 3
Elemental analysis and mass spectroscopic data for isolated compounds
Complex
Formula
Anal. Found (Calc.)
C (%) H (%) N (%)
Mass spectra (EI, 70 eV)
(m/z)
Cp(CO)2FeSiMe2O(2-C5H4N) (1a)
Cp*(CO)2FeSiMe2O(2-C5H4N) (1b)
C14H15FeNO3Si 50.95
4.57
4.27
301 (Mꢂꢃ
/
CO, 7)
273 (Mꢂꢃ
152 (Mꢂꢃ
100)
343 (Mꢂꢃ
2Me, 16) 152(Mꢂꢃ
100)
273 (Mꢂꢃ
208 (Mꢂꢃ
COꢃ
/
2CO, 31)
(51.08) (4.59) (4.25) 258 (Mꢂꢃ
/2COꢃ
/
Me, 5)
/Cp(CO)2Fe,
C19H25FeNO3Si 57.46
6.19
3.51
371 (Mꢂꢃ
COꢃ
/CO, 5)
/2CO, 10)
(57.15) (6.31) (3.51) 341 (Mꢂꢃ
/
/
/
Cp*(CO)2Fe,
Cp(CO)Fe[k2(Si,N)-SiMe2O(2-C5H4N)] (2a) C13H15FeNO2Si 51.64
5.09
4.67
301 (Mꢂ, 16)
COꢃ
Cp(CO)Fe, 59)
371 (Mꢂ, 12)
(58.22) (6.79) (3.77) 341 (Mꢂꢃ
2 Me, 100)
152 (Mꢂꢃ
Cp*(CO)Fe, 33)
153 (Mꢂ, 40)
(54.86) (7.23) (9.14) 138 (Mꢂꢃ
Me, 100)
52.26 7.18 7.78
183 (Mꢂ, 26)
(52.43) (7.15) (7.64) 152 (Mꢂꢃ
OMe, 11)
/CO, 100)
(51.84) (5.02) (4.65) 258 (Mꢂꢃ
152(Mꢂꢃ
/
/Me, 20)
/
/Cp, 16)
/
Cp*(CO)Fe[k2(Si,N)-SiMe2O(2-C5H4N)] (2b) C18H25FeNO2Si 57.78
6.77
3.73
343 (Mꢂꢃ
190 (11)
/CO, 35)
/
/
HsiMe2O(2-C5H4N) (3)
C7H11NOSi
C8H13NO2Si
54.62
7.33
9.10
152(Mꢂꢃ
168 (Mꢂꢃ
/
H, 47)
/
MeOSiMe2O(2-C5H4N) (9)
/Me, 100)
/
hydroxypyridine (4.76 g, 50.0 mmol) in 60 ml of THF
over 45 min at r.t. with stirring. After further stirring for
3 h, white precipitates were filtered off and washed with
three 10 ml portions of hexane. The filtrate and
washings were combined and all volatiles were removed
3.5. Synthesis of Cp(CO)Fe[k2(Si,N)-SiMe2O(2-
C5H4N)] (2a)
3.5.1. Method A (from 1a)
An H-shaped glass tube (6 mm i.d.) connected to a
ground glass joint through a Teflon needle valve was
charged with a solution of 1a (165 mg, 0.501 mmol) in 4
from the solution under reduced pressure (at ꢀ20 Torr)
/
to yield a yellow oil. Fractional distillation of the oil
afforded colorless liquid of 3 (5.39 g, 35.2 mmol) in 70%
ml of hexane. The solution was degassed by freezeꢁ
pumpꢁthaw technique and the needle valve was closed.
The tube was irradiated at 10 8C. The reaction mixture
was degassed every 20 min of irradiation by freezeꢁ
pumpꢁthaw technique. After irradiation for 60 min,
/
1
yield. B.p.: 90 8C/24 Torr. H-NMR (C6D6): d 0.39 (d,
/
3
2.8 Hz, 6H, SiMe2), 5.34 (septet, JHH
3JHH
ꢀ
/
ꢀ2.8 Hz,
/
1H, SiH), 6.39 (ddd, 1H, Jꢀ
6.58 (dd, 1H, Jꢀ8.3, 0.7 Hz, OC5H4N), 7.00 (ddd, 1H,
Jꢀ8.3, 7.1, 2.0 Hz, OC5H4N), 8.00 (dd, 1H, Jꢀ5.3, 2.0
Hz, OC5H4N). 13C{1H}-NMR (C6D6): d ꢃ
1.2 (SiMe2),
/
7.1, 5.3, 0.7 Hz, OC5H4N),
/
/
/
/
/
the tube was flame-sealed on a vacuum line. The
reaction mixture was warmed to 60 8C to dissolve the
red precipitates and then gradually cooled down and
/
112.5, 117.1, 139.1, 147.5, 163.1 (pyridine ring).
Table 4
29Si-, 31P-NMR, IR, and UVꢁ
/
vis spectroscopic data for new compounds
Complex
d
IR (KBr), nFeCꢀO
(cmꢃ1
UVꢁvis (hexane),
lmax (nm) (log o )
/
)
29Si-NMR (C6D6) 31P-NMR (C6D6)
Cp(CO)2FeSiMe2O(2-C5H4N) (1a)
Cp*(CO)2FeSiMe2O(2-C5H4N) (1b)
Cp(CO)Fe[k2(Si,N)-SiMe2O(2-C5H4N)] (2a)
Cp*(CO)Fe[k2(Si,N)-SiMe2O(2-C5H4N)] (2b)
HSiMe2O(2-C5H4N) (3)
71.9
72.5
113.5
114.4
3.6
1992 vs, 1938 vs
1981 vs, 1923 vs
1884 s
271 (3.9), 313 (3.3)
254 (3.9), 285 (3.7), 340 (3.1)
246 (3.8), 323 (3.3), 405 (2.9)
255 (3.8), 339 (3.3), 427 (2.9)
1886 s
nSiH 2156 s
c
a
Cp(CO)(PMe3)FeSiMe2O(2-C5H4N) (6)
Cp(CO)(PPh3)FeSiMe2O(2-C5H4N) (7)
MeOSiMe2O(2-C5H4N) (9)
79.7
77.2
33.6
80.6
b
1903 s
c
ꢃ
/
1.2
rSiOMe 1190 m
a
2JPSi
2JPSi
ꢀ
ꢀ/
/
44 Hz.
36 Hz.
IR value of 3 and 9 were measured in NaCl plate.
b
c

196
T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ199
/
stored at ꢃ
/
30 8C for 2 days to afford red crystals. Its
0.06 mmol). The solution was degassed by freezeꢁ
/
mother liquor was removed by decantation and the
crystals were washed several times with hexane, and
dried under vacuum to give red crystals of 2a (72 mg,
0.24 mmol, 48%). M.p.: 128 8C (dec.). 1H-NMR (C6D6):
d 0.92, 1.05 (s, s, 3Hx2, SiMe2), 4.09 (s, 5H, C5H5), 5.72
pumpꢁthaw technique and the tube was flame-sealed
on a vacuum line. The sample was heated and the
1
reaction was monitored by H-NMR spectroscopy. The
reaction did not occur below 90 8C for 7 days.
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2b (8 mg, 0.02 mmol) and hexamethylben-
zene was also prepared in a similar manner. The sample
was heated and the reaction was monitored by 1H-NMR
spectroscopy. The reaction did not occur below 90 8C
for 7 days.
/
(ddd, 1H, Jꢀ
Jꢀ8.2, 1.3 Hz, OC5H4N), 6.55 (ddd, 1H, Jꢀ
5.9, 1.7 Hz,
/
7.4, 5.9, 1.3 Hz, OC5H4N), 6.33 (dd, 1H,
/
/8.2, 7.4,
1.7 Hz, OC5H4N), 7.73 (dd, 1H, Jꢀ
/
OC5H4N). 13C{1H}-NMR (C6D6): d 8.8 (SiMe), 9.1
(SiMe), 80.4 (C5H5), 111.0, 114.2, 138.0, 155.7, 170.7
(pyridine ring), 223.4 (FeCO).
3.8. Reaction of 2 with PPh3
3.5.2. Method B (from 5a with hydrosilane 3)
A solution of 5a (1.02 g, 4.09 mmol) and 3 (789 mg,
5.15 mmol) in 7 ml of hexane was irradiated in a manner
similar to that of 1a as described above, except that the
solution was degassed every 1 h of irradiation, and total
period of irradiation was 4 h. Crystallization from
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2a (6 mg, 0.02 mmol), PPh3 (8 mg, 0.03
mmol), and hexamethylbenzene was prepared in a
manner analogous to Section 3.7. The sample was
heated and the reaction was monitored by 1H- and
31P-NMR spectroscopy. The reaction did not occur
below 80 8C. Complex 2a was gradually converted to a
single product Cp(CO)(PPh3)FeSiMe2O(2-C5H4N) (7)
above 100 8C. The reaction did not complete within 7
days at 100 8C. The yield of 7 was 13%, and 87% of 2a
still remained intact after 7 days at 100 8C. When the
mixture was heated to 150 8C, black precipitates
formed. In addition, the NMR signals broadened,
although 2a was still a major component after 2 days
at 150 8C. Complex 7: 1H-NMR: d 0.65, 0.79 (s, s,
hexane at ꢃ75 8C gave deep red crystals of 2a (655
/
mg, 2.17 mmol, 53%).
3.6. Synthesis of Cp*(CO)Fe[k2(Si,N)-SiMe2O(2-
C5H4N)] (2b)
3.6.1. Method A (from 1b)
Photolysis of 1b (202 mg, 0.507 mmol) was carried out
in a manner similar to that of 1a to yield red crystals of
2b (128 mg, 0.345 mmol, 68%). M.p.: 112 8C (dec.). 1H-
NMR (C6D6): d 0.94, 1.04 (s, s, 3Hx2, SiMe2), 1.54 (s,
3Hx2, SiMe), 4.30 (s, 5H, Cp), 6.4ꢁ
/
8.2 (m, 19H,
15H, C5Me5), 5.88 (ddd, 1H, Jꢀ
OC5H4N), 6.37 (dd, 1H, Jꢀ8.1, 1.0 Hz, OC5H4N),
6.59 (ddd, 1H, Jꢀ8.1, 7.4, 1.6 Hz, OC5H4N), 7.77 (dd,
1H, Jꢀ
5.9, 1.6 Hz, OC5H4N). 13C{1H}-NMR (C6D6):
d 7.3 (SiMe), 9.9 (SiMe), 10.5 (C5Me5), 89.8 (C5Me5),
110.5, 114.6, 137.6, 154.5, 170.6 (pyridine ring), 224.4
(FeCO).
/
7.4, 5.9, 1.0 Hz,
OC5H4NꢂPPh3).
/
/
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2b (8 mg, 0.02 mmol), PPh3 (24 mg, 0.09
mmol), and hexamethylbenzene prepared in a similar
manner was also heated and the reaction was monitored
/
/
1
by H- and 31P-NMR spectroscopy. The reaction did
not occur below 150 8C for 8 days.
3.9. Reaction of 2a with PMe3
3.6.2. Method B (from 5b with hydrosilane 3)
Photolysis of 5b (640 mg, 2.00 mmol) and 3 (388 mg,
2.53 mmol) was carried out in a manner similar to that
of 5a and 3 to give red crystals of 2b (360 mg, 0.970
mmol, 49%).
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2a (7 mg, 0.02 mmol), PMe3 (2.5 mg, 0.03
mmol), and hexamethylbenzene was prepared in a
manner similar to that for 2a and PPh3. The sample
1
3.6.3. Method C (from 10 with hydrosilane 3)
Photolysis of 10 (131 mg, 0.500 mmol) and 3 (85 mg,
0.55 mmol) was carried out in a manner similar to that
was heated and the reaction was monitored by H- and
31P-NMR spectroscopy. The reaction did not occur at
80 8C and was slow at 100 8C. After 3 days heating at
100 8C, 60% of 2a was converted to Cp(CO)(PMe3)Fe-
SiMe2O(2-C5H4N) (6) with formation of a little amount
of 5b and 3. Recrystallization from hexane at ꢃ75 8C
/
afforded red crystals of 2b (64 mg, 0.17 mmol, 34%).
1
of unidentified products. Complex 6: H-NMR (C6D6):
2
d 0.97, 0.99 (s, s, 3Hx2, SiMe), 1.03 (d, 9H, JPH
3.7. Thermal reaction of 2
ꢀ9.2
/
3
Hz, PMe3), 4.18 (d, 5H, JPH
(ddd, 1H, Jꢀ7.1, 4.8, 1.1 Hz, OC5H4N), 6.63 (dd, 1H,
Jꢀ8.2, 1.1 Hz, OC5H4N), 7.09 (ddd, 1H, Jꢀ8.2, 7.1,
2.2 Hz, OC5H4N), 8.19 (dd, 1H, Jꢀ4.8, 2.2 Hz,
OC5H4N).
ꢀ1.4 Hz, C5H5), 6.44
/
A Pyrex NMR tube (5 mm o.d.), which was connected
to a ground glass joint through a Teflon needle valve,
was charged with a benzene-d6 solution of 2a (6 mg, 0.02
mmol) and internal standard hexamethylbenzene (1 mg,
/
/
/
/

T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ
/199
197
3.10. Reaction of 2a with MeOH in the absence of PPh3
3.14. Reaction of 9 with NaOMeꢁMeOH
/
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2a (6 mg, 0.02 mmol), MeOH (1.0 ml, 0.02
mmol), and hexamethylbenzene was prepared in a
manner similar to that of 2a and PPh3. The sample
was heated and the reaction was monitored by 1H-NMR
spectroscopy. The reaction proceeded slowly at 100 8C.
After 8 days at 100 8C, 17% of 2a reacted and
SiMe2(OMe)2 was formed in 12% yield. The resultant
product containing Fe was not characterized.
To a benzene-d6 solution of 9 (5 mg, 0.03 mmol), and
hexamethylbenzene was added MeOH (11 ml, 0.27
mmol) and the reaction was monitored at r.t. by H-
NMR spectroscopy. After 1 h, 7% of 9 had reacted.
Then, to it was added powdered NaOMe (1.0 mg, 0.019
mmol) at r.t. The reaction completed within 10 min to
give SiMe2(MeO)2 quantitatively.
1
3.15. X-ray crystal structure determination of 1b and 2b
Single crystals of 1b and 2b were obtained by
recrystallization of the isolated products. A suitable
part of each crystal was cut out with blade and mounted
on a glass capillary. The intensity data were collected on
a Rigaku Raxis-Rapid Imaging Plate diffractometer
3.11. Reaction of 2a with MeOH in the presence of PPh3
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2a (6 mg, 0.02 mmol), MeOH (1.0 ml, 0.02
mmol), PPh3 (8 mg, 0.03 mmol), and hexamethylben-
zene was prepared in a manner similar to that of 2a and
PPh3. The reaction did not occur after 5 h at 80 8C.
Another sealed tube containing a benzene-d6 solution
of 2a (8 mg, 0.02 mmol), MeOH (10 ml, 0.25 mmol, nine
equivalents), PPh3 (20 mg, 0.075 mmol), and hexam-
ethylbenzene was prepared in the same manner. After 24
h at r.t., 3% of 2a reacted and small amount of
Cp(CO)(PPh3)FeH (8) [24] and SiMe2(OMe)2 formed.
with graphite monochromated MoꢁKa radiation at
/
20(2) 8C. The space group was determined based on
the systematic absences. The structures were solved by
Table 5
Crystal data and structural refinement for complexes 1b and 2b
1b
2b
Formula
C
19H25FeNO3Si C18H25FeNO2Si
399.34 371.33
0.3ꢄ0.3ꢄ 0.1ꢄ0.1ꢄ
Formula weight
Crystal size (mm)
Color of crystals
Temperature (8C)
Crystal system
Space group
/
/0.2
/
/
0.1
Yellow
20(2)
Monoclinic
Red
20(2)
Monoclinic
3.12. Reaction of 2a with NaOMeꢁ/MeOH in the
presence of PPh3
P21/n (#14)
9.2384(3)
13.4781(4)
16.5016(5)
97.3323(12)
2037.91(11)
4
P21/c (#14)
13.9956(5)
7.9981(3)
16.9069(7)
95.4819(6)
1883.87(12)
4
˚
a (A)
A vacuum-sealed NMR tube containing a benzene-d6
solution of 2a (8 mg, 0.02 mmol), NaOMe (1.0 mg, 0.019
mmol, 0.7 equivalents), MeOH (10 ml, 0.25 mmol, nine
equivalents), PPh3 (20 mg, 0.075 mmol), and hexam-
ethylbenzene was prepared in a manner similar to that
of 2a and PPh3. The reaction completed within 1 h at r.t.
Quantitative formation of Cp(CO)(PPh3)FeH (8) [24]
˚
b (A)
˚
c (A)
b (8)
3
V (A )
˚
Z
Dcalc (g cmꢃ3
)
1.302
0.815
1.309
0.872
Absorption coefficient (mmꢃ1
u Range for data collection
hkl limits
)
1.96ꢁ
ꢃ
ꢃ
ꢃ
/27.48
1.46ꢁ27.48
/
1
and SiMe2(OMe)2 was confirmed by H-NMR spectro-
scopy.
/
11, 11;
17, 17;
21, 21
ꢃ
/
18, 18;
10, 10;
21, 21
/
ꢃ
/
/
ꢃ/
Reflections collected
Independent reflections
19 014
4647
15 904
4296
3.13. Synthesis of MeOSiMe2O(2-C5H4N) (9)
(Rint
4065
226
ꢀ
/
0.0392) (Rint
ꢀ
/
0.0555)
Reflections with Iꢀ
Number of parameters
R indices (I ꢀ2s(I))
/
2s(I)
3024
208
Silane 9 was synthesized by a procedure analogous to
that for 3, using MeOSiMe2Cl (2.93 g, 23.5 mmol), Et3N
(2.37 g, 23.5 mmol), and 2-hydroxypyridine (1.91 g, 20.0
mmol). Fractional distillation afforded a colorless liquid
of 9 (2.04 g, 11.1 mmol) in 56% yield. B.p.: 115 8C/12
a
a
/
R1ꢀ/0.0348
R1ꢀ
wR2ꢀ
R1ꢀ0.0811
wR2ꢀ0.1222
1.043
0.308; ꢃ
/0.0481
b
c
wR2ꢀ
R1ꢀ0.0418
wR2ꢀ0.0968
1.040
/
0.0920
/
0.1001
R indices (all data)
/
/
/
/
Goodness-of-fit on F2
1
Torr. H-NMR (C6D6): d 0.44 (s, 6H, SiMe2), 3.57 (s,
Largest difference peak and hole 0.238; ꢃ
/
0.275
/0.364
ꢃ3
˚
(e A
)
3H, OMe), 6.39 (ddd, 1H, Jꢀ
OC5H4N), 6.60 (dd, 1H, Jꢀ8.2, 0.8 Hz, OC5H4N),
7.01 (ddd, 1H, Jꢀ8.2, 7.3, 2.0 Hz, OC5H4N), 7.97 (dd,
1H, Jꢀ
5.0, 2.0 Hz, OC5H4N). 13C{1H}-NMR (C6D6):
d ꢃ2.0 (SiMe2), 50.8 (OMe), 112.7, 117.2, 139.1, 147.5,
162.5 (pyridine ring).
/
7.3, 5.0, 0.8 Hz,
/
a
R1ꢀ
wR2ꢀ
/
SjjFojꢃ
/
jFcjj/SjFoj.
/
b
/
[S[w(F2oꢃ
/
F2c)2]/S[w(F2o)2]]1/2
;
w
w
ꢃ1ꢀ
ꢃ1ꢀ
/
s2(F2o)ꢂ
/
(0.0515P)2ꢂ
/
(F2oꢂ
/
2F2c)/3.
/
0.5670P; Pꢀ
/
c
wR2ꢀ
/
[S[w(F2oꢃ
/
F2c)2]/S[w(F2o)2]]1/2
;
/
s2(F2o)ꢂ(0.0416P)2ꢂ
/
/
/
2.1377P; Pꢀ
/
(F2oꢂ2F2c)/3.
/

198
T. Sato et al. / Journal of Organometallic Chemistry 669 (2003) 189ꢁ
/199
Trans. (1997) 3531;
Patterson and Fourier transform methods, and all non-
hydrogen atoms were refined by full-matrix least-
squares techniques with anisotropic displacement para-
meters using SHELXL-97 [29]. All hydrogen atoms were
placed at their geometrically calculated positions
(c) M. Okazaki, H. Tobita, H. Ogino, Chem. Lett. (1997) 437;
(d) M. Okazaki, H. Tobita, Y. Kawano, S. Inomata, H. Ogino, J.
Organomet. Chem. 553 (1998) 1;
(e) M. Okazaki, S. Ohshitanai, H. Tobita, H. Ogino, Chem. Lett.
(2001) 952;
˚ ˚
(dCH
ꢀ0.96 A for methyl hydrogen atoms and 0.93 A
/
(f) M. Okazaki, S. Ohshitanai, M. Iwata, H. Tobita, H. Ogino,
Coord. Chem. Rev. 226 (2002) 167;
for aromatic hydrogen atoms) and refined riding on the
corresponding carbon atoms with isotropic thermal
(g) M. Okazaki, S. Ohshitanai, H. Tobita, H. Ogino, J. Chem.
Soc. Trans. (2002) 2061.
parameters (Uꢀ
The final R indices against reflections with I ꢀ
were R1ꢀ0.0348 and wR2ꢀ0.0920 for 1b, and R1ꢀ
0.0481 and wR2ꢀ0.1001 for 2b. The crystal data and
/1.5U(Cmethyl
)
and 1.2U(Caromatic)).
[4] P.I. Djurovich, A.L. Safir, N.L. Keder, R.J. Watts, Inorg. Chem.
31 (1992) 3195.
/2s(I)
/
/
/
[5] L. Hao, H.-G. Woo, A.-M. Lebuis, E. Samuel, J.F. Harrod,
Chem. Commun. (1998) 2013.
/
[6] M. Stradiotto, K.L. Fujdala, T.D. Tilley, Chem. Commun. (2001)
1200.
analytical conditions are listed in Table 5.
[7] T. Sato, H. Tobita, H. Ogino, Chem. Lett. (2001) 854.
[8] A.R. Katritzky, in: C.W. Rees (Ed.), Comprehensive Heterocyclic
Chemistry, Pergamon, New York, 1984.
4. Supplementary material
[9] (a) T.D. Tilley, in: S. Patai, Z. Rappoport (Eds.), The Chemistry
of Organic Silicon Compounds (Chapter 24), Wiley, New York,
1989;
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Center, CCDC no. 193001 for compound 1b and
CCDC no. 193002 for compound 2b. Copies of this
information may be obtained upon application to The
Director, CCDC, 12 Union Road, Cambridge, CB2
(b) M.S. Eisen, in: Z. Rappoport, Y. Apeloig (Eds.), The
Chemistry of Organic Silicon Compounds 2 (Chapter 35), Wiley,
New York, 1998;
(c) H. Ogino, H. Tobita, Adv. Organomet. Chem. 42 (1998)
223;
1RZ, UK (fax: ꢂ44-1223-336-033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
/
(d) J.Y. Corey, J. Braddock-Wilking, Chem. Rev. 99 (1999)
175.
[10] W.S. Sheldrick, in: S. Patai, Z. Rappoport (Eds.), The Chemistry
of Organic Silicon Compounds (Chapter 3), Wiley, New York,
1989.
Acknowledgements
[11] L. Stefaniak, Tetrahedron 32 (1976) 1065.
[12] M.J. Buchanan, R.H. Cragg, A. Steltner, J. Organomet. Chem.
120 (1976) 189.
This work was supported by a Grant-in-Aid for
Scientific Research (No. 14204065) and by Grants-in-
Aid for Scientific Research on Priority Areas (Nos.
4078202 and 14044010) from the Ministry of Education,
Culture, Sports, Science and Technology, Japan. We
thank Dow Corning Toray Silicone Co., Ltd. and Shin-
Etsu Chemical Co. Ltd., for gifts of silicon compounds.
[13] (a) C.L. Randolph, M.S. Wrighton, J. Am. Chem. Soc. 108 (1986)
3366;
(b) Y. Kawano, H. Tobita, H. Ogino, J. Organomet. Chem. 428
(1992) 125;
(c) H.K. Sharma, K.H. Pannell, Chem. Rev. 95 (1995) 1351.
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¨
(c) J.R. Koe, H. Tobita, H. Ogino, Organometallics 11 (1992)
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