Synthesis and spectroscopic properties of novel silacyclic compounds containing a titanium and some chalcogen atoms

Article abstract of DOI:10.1246/bcsj.79.1573

Novel silacyclic compounds containing a titanium and some chalcogen atoms, [Tbt(Mes)Si(μ-Ch)₂TiCp₂] and [Tbt(Mes)Si(μ-Ch)(μ- Ch₂)TiCp₂] (Ch = S and Se; Tbt = 2,4,6- tris[bis(trimethylsilyl)methyl]phenyl; Mes = mesityl; Cp = cyclopentadienyl), were synthesized by the reactions of the disilene Tbt(Mes)Si=Si(Mes)Tbt with the corresponding [Cp₂TiCh₅] (Ch = S and Se). The spectroscopic properties of these compounds are presented together with the results of theoretical calculations.

Full text of DOI:10.1246/bcsj.79.1573

ꢀ 2006 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 79, No. 10, 1573–1579 (2006) 1573
Synthesis and Spectroscopic Properties of Novel Silacyclic Compounds
Containing a Titanium and Some Chalcogen Atoms
ꢀ
Nobuhiro Takeda, Taro Tanabe, and Norihiro Tokitoh
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011
Received April 7, 2006; E-mail: tokitoh@boc.kuicr.kyoto-u.ac.jp
Novel silacyclic compounds containing a titanium and some chalcogen atoms, [Tbt(Mes)Si(ꢀ-Ch)2TiCp2] and
[Tbt(Mes)Si(ꢀ-Ch)(ꢀ-Ch2)TiCp2] (Ch ¼ S and Se; Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Mes = mesityl;
Cp = cyclopentadienyl), were synthesized by the reactions of the disilene Tbt(Mes)Si=Si(Mes)Tbt with the correspond-
ing [Cp2TiCh5] (Ch ¼ S and Se). The spectroscopic properties of these compounds are presented together with the
results of theoretical calculations.
The chemistry of metal polychalcogenido complexes has
been extensively studied from the viewpoint of not only funda-
mental chemistry but also their potential for applications.1–4
In recent years, silanechalcogenolato complexes of transition
metals have attracted much attention as potential precursors
for the controlled synthesis of mixed-metal chalcogenido clus-
ters, and a number of such complexes have been synthe-
sized.5–8 By contrast, there are few reports on the chemistry
of cyclic compounds having an Si–(Ch)n–M (Ch = chalcogen,
M = transition metal) linkage such as chelating silanedichal-
cogenolato complexes of transition metals.9–14 Silacyclic com-
pounds containing titanium and chalcogen atoms are very rare,
and only three examples have been published to date; [Me2Si-
(ꢀ-S)2Ti{C5(Me)H4}2],12 [Ph2Si(ꢀ-S)2Ti(C5H5)2],11 and [{t-
Bu(Ph)Si}2(ꢀ-S)2Ti(C5H5)2].15 In addition, to the best of our
knowledge, there is no report on the synthesis of cyclic com-
pounds having silicon and transition-metal atoms bridged by
selenium atoms. Even for the carbon analogues, only a few ex-
amples, such as [Cp2Ti(ꢀ-S)2C=CR2],16 [Cp2Ti(ꢀ-S2)2CR2],
and [Cp2Ti(ꢀ-S)(ꢀ-S3)CR2],17 have been reported.
On the other hand, we have reported the synthesis of a vari-
ety of novel compounds of heavier main group elements, such
as cyclic polychalcogenides containing a group 14 or 15 ele-
ment,18–25 multiply bonded compounds containing heavier group
14 or 15 elements,19,26 and aromatic compounds containing a
heavier group 14 element,27 by taking advantage of an efficient
steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl (Tbt). In addition, we have synthesized an overcrowded
disilene 1 having Tbt and mesityl (Mes) groups and found that
it dissociates to the corresponding silylene 2 under mild condi-
tions such as heating at 60 ꢁC (Scheme 1).28–30 It was shown
that 2 reacts with S8 to give the corresponding tetrathiosilolane
Tbt(Mes)SiS4 in a good yield via the insertion of the silylene
into the S–S bond accompanied by the desulfurization.29,30
In this paper, we present the reactions of silylene 2 with
titanocene pentachalcogenides giving novel silacyclic com-
pounds containing a titanium and some chalcogen atoms
together with the spectroscopic properties of the resulting
heterocyclic compounds.
Results and Discussion
Synthesis of Silacyclic Compounds Containing Ti and S
Atoms. After silylene 2, generated from disilene 1, was al-
lowed to react with an equimolar amount of titanocene penta-
1
sulfide in THF at 60 ꢁC for 40 h, the H NMR spectrum of the
crude mixture showed the formation of the five-membered ring
compound 3, Tbt(Mes)SiS4 (ꢂ15%),24 Tbt(Mes)Si(ꢀ-S)2Si-
(Mes)Tbt (ꢂ8%)31 and unreacted titanocene pentasulfide.
Compound 3, having a novel ring structure consisting of Si,
Ti, and S atoms, was isolated as air-stable dark green crystals
in 36% yield (Scheme 2); however, all the compounds except
for 3 could not be separated from the mixture. The structure of
3 was determined by the 1H, 13C, and 29Si NMR spectra, mass
spectrum, and elemental analysis. Although titanocene penta-
sulfide is known to react with alkynes to give the correspond-
ing ethylene-1,2-dithiolato complexes,1,32,33 no adduct be-
tween titanocene pentasulfide and disilene 1 was obtained in
this reaction.
On the other hand, when benzene was used as the reaction
solvent instead of THF, the reaction of 1 with titanocene
pentasulfide gave a mixture of 3 (ꢂ60%) and a six-membered
ring compound 4 (ꢂ20%) (Scheme 2) together with a small
amount of Tbt(Mes)SiS4 and Tbt(Mes)Si(ꢀ-S)2Si(Mes)Tbt.
Attempts to separate the mixture of 3 and 4 by gel permeation
S
S
Tbt
THF
60 °C, 40 h
Si
TiCp2
S
Mes
Cp2TiS5
+
1/2 1
3 (36%)
Tbt
Sm
Sn
Tbt
Tbt
Tbt
R
R
60 °C
Si
TiCp2
+
3
Tbt: R = CH(SiMe3)2
Mes: R = Me
2
Si Si
Si
benzene
60 °C, 15 h
Mes
Mes
Mes
Mes
Cp = C5H5
R
(~60%)
4 (m+n=4, ~20%)
1
2
Scheme 1. Generation of silylene 2 from disilene 1.
Scheme 2. Reaction of disilene 1 with [Cp2TiS5].
Published on the web October 10, 2006; doi:10.1246/bcsj.79.1573

1574 Bull. Chem. Soc. Jpn. Vol. 79, No. 10 (2006)
Silacycles Containing Ti and S or Se Atoms
Table 1. Observed and Calculated 29Si NMR Chemical
Shifts for the Silacyclic Compounds Containing a Tita-
nium and Some Chalcogen Atoms
a mixture of
3 and 4
(3:4 = 2:1)
Tbt
S
S
Ph3P (excess)
Ph3P (1 equiv.)
3
Si
TiCp2
C6D6, 60 °C, 4 h
− Ph3P=S
C6H6, 60 °C, 3 d
− Ph3P=S
Mes
5 (91%)
Compound
Observed ꢂSi/ppma)
Calculated ꢂSi/ppmb),c)
Scheme 3. Desulfurization of 3 and 4.
3
5
6
7
46.5
ꢄ52:7
32.0
ꢄ57:2
66.6
ꢄ56:8
81.3
ꢄ53:2
Se Se
Tbt
Cp2TiSe5
+
6 (45%)
TiCp2
1/2 1
Si
benzene
Se
Mes
60 °C, 15 h
a) 59 MHz, in C6D6. b) Both of Tbt and Mes groups are
replaced by 2,6-dimethylphenyl groups. c) Calculated level:
GIAO-B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d).
Scheme 4. Reaction of disilene 1 with [Cp2TiSe5].
Tbt Se
Si
Mes Se
Ph3P (1 equiv.)
6
TiCp2 7 (95%)
Table 2. Observed and Calculated 77Se NMR Chemical
Shifts for the Silacyclic Compounds Containing a Tita-
nium and Some Selenium Atoms
C6H6, r.t., < 30 min
− Ph3P=Se
Scheme 5. Deselenation of 6.
Observed ꢂSe
/ppm
Calculated ꢂSe
Compound
Position
liquid chromatography (GPLC), wet column chromatography
(WCC), and recrystallization were unsuccessful. The mass
spectrum of the mixture of 3 and 4 showed a peak envelope
corresponding to that of the six-membered ring compound,
C46H81S4Si7Ti (½M þ Hꢃþ), without the peaks in the region
of the larger mass numbers. Since the thermolysis of the mix-
ture of 3 and 4 (3:4 = 5:3) in THF-d8 at 60 ꢁC for 12 h and the
reaction of 3 with elemental sulfur (5 molar amounts as S) in
C6D6 at 60 ꢁC for 12 h resulted in no reaction, the interconver-
sion between 3 and 4 does not occur in the reaction of 1 with
titanocene pentasulfide.
/ppma),b)
6c)
ꢃ
ꢄ
ꢅ
681.0
1282.6
407.5
691.6
1489.2
530.2
7d)
228.1
260.7, 261.6
a) Both of Tbt and Mes groups are replaced by 2,6-dimethyl-
phenyl groups. b) Calculated level: GIAO-B3LYP/6-311+
G(2d,p)//B3LYP/6-31G(d). c) 95 MHz, in C7D8 at 330 K.
d) 95 MHz, in C6D6 at 298 K.
The reaction of a mixture of 3 and 4 (3:4 = 2:1) with an
excess amount of Ph3P in C6D6 at 60 ꢁC for 4 h resulted in
the quantitative conversion to 3 along with the formation of
a 0.33 molar amount of Ph3P=S (Scheme 3), which supports
the six-membered ring structure of 4. The desulfurization of
3 with an equimolar amount of Ph3P in benzene at 60 ꢁC for
3 days gave the corresponding silanedithiolato complex 5 as
orange crystals in 91% yield together with Ph3P=S (quant).
The characterization of 5 was also performed by using spectro-
scopic data. Attempts to desulfurize 3 with an excess amount
of various phosphine reagents, R3P (R ¼ Ph, n-Bu, Me2N,
MeO, and Me), only resulted in the formation of 5 in a quan-
titative yield without further desulfurization of 5.
Synthesis of Silacyclic Compounds Containing Ti and Se
Atoms. The reaction of disilene 1 with titanocene pentase-
lenide in C6D6 at 60 ꢁC for 15 h resulted in the formation of
the corresponding five-membered ring compound 6 without
yielding other cyclic compounds such as the selenium analog
of 4 (Scheme 4). Since 6 is sensitive to air and moisture, the
isolation of 6 required the purification of the reaction mixture
with wet column chromatography using dried silica gel under
argon atmosphere (isolated yield: 45%; green crystals). The
structure of 6 was determined by 1H, 13C, 29Si, 77Se NMR
spectroscopy and mass spectroscopy. X-ray structural analysis
also supported its structure, although detailed structural fea-
tures can not be discussed because of the poor quality of the
crystals. The reactions of 1 with titanocene pentaselenide in
various solutions such as benzene, THF, and ether also gave
6 in similar yields without the formation of other cyclic com-
pounds. These results are in sharp contrast to the reactions with
the sulfur analog which gave a mixture of 3 and 4 when ben-
β
α
Se Se
Tbt
Si
TiCp2
Se
Mes
γ
Chart 1.
zene was used as the solvent.
The deselenation of 6 with an equimolar amount of Ph3P
proceeded smoothly at room temperature to give the corre-
sponding silanediselenolato complex 7, which is sensitive to
air and moisture (Scheme 5). Compound 7 was isolated
as yellow crystals in 95% yield upon the separation from
Ph3P=Se, which is only slightly soluble in hexane, by filtra-
tion of a hexane suspension of the reaction mixture. Com-
pound 7 was characterized by the spectroscopic data.
Deselenation at room temperature appeared to occur more
easily than the desulfurization of the mixture of 3 and 4, which
required heating at 60 ꢁC. However, further deselenation of 7
with phosphine reagents, such as R3P (R ¼ Ph, Bu, Me2N,
and Me), did not proceed even on heating at 100 ꢁC or by
irradiating (ꢁ ¼ 300{500 nm).
NMR Spectra. Tables 1 and 2 show the 29Si NMR data of
3, 5, 6, and 7 and 77Se NMR chemical shifts of 6 and 7, respec-
tively, along with the calculated chemical shifts of the model
compounds, 30, 50, 60, and 70, in which both of the Tbt and
Mes groups of the real molecules are replaced by 2,6-dimeth-
ylphenyl (Dmp) groups (Chart 1). The observed values are
consistent with the calculated ones, and this result supports
the proposed structure of these compounds. It is notable that
the 29Si NMR chemical shifts of four-membered ring com-

N. Takeda et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 10 (2006) 1575
0.4
0.3
0.2
0.1
0.8
0.6
0.4
0.2
0
417
372
3
5
6
442
555
648
7
418
598
600
740
0
300
300
400
500
wavelength/nm
600
700
800
400
500
700
800
wavelength/nm
Fig. 2. UV–vis spectra of 5 (blue line) and 7 (red line) in
hexane solutions (1 ꢅ 10ꢄ4 mol Lꢄ1).
Fig. 1. UV–vis spectra of 3 (blue line) and 6 (red line) in
hexane solutions (1 ꢅ 10ꢄ4 mol Lꢄ1).
Table 3. Observed and Calculated Absorption Maxima of 3, 5, 6, and 7
Observed ꢁmax (")
/nm
Calculated ꢁmax (f)a),b)
/nm
Compound
Transitions
Atomic characterc)
3
417 (3:2 ꢅ 103)
555 (1:3 ꢅ 103)
648 (1:2 ꢅ 103)
396 (0.0100)
552 (0.0122)
600 (0.0067)
HOMOꢄ5 ! LUMO
HOMOꢄ1 ! LUMO
HOMO ! LUMO
Dmp ! Ti
S3 (pz) ! Ti
S3 (pz) ! Ti
6
5
7
442 (1:5 ꢅ 103)
598 (6:3 ꢅ 102)
740 (4:7 ꢅ 102)
397 (0.0129)
580 (0.0116)
654 (0.0085)
HOMOꢄ5 ! LUMO
HOMOꢄ1 ! LUMO
HOMO ! LUMO
HOMOꢄ3 ! LUMO
HOMOꢄ1 ! LUMO
HOMO ! LUMO
HOMOꢄ3 ! LUMO
HOMOꢄ1 ! LUMO
HOMO ! LUMO
Dmp ! Ti
Se3 (pz) ! Ti
Se3 (pz) ! Ti
Dmp ! Ti
S2 (pz) ! Ti
S2 (pz) ! Ti
Dmp ! Ti
Se2 (pz) ! Ti
Se2 (pz) ! Ti
372 (6:0 ꢅ 103)
392 (0.0452)
652 (0.0006)
684 (0.0024)
418 (2:0 ꢅ 103)
407 (0.0470)
758 (0.0010)
760 (0.0024)
a) Both of Tbt and Mes groups are replaced by 2,6-dimethylphenyl groups. b) Calculated level: TD-B3LYP/
6-31G(d)//B3LYP/6-31G(d). c) The major atomic character of the transition.
pounds 5 and 7 are observed in the high-field region. This is
interesting because the NMR spectra of four-membered ring
compounds generally show normal chemical shifts, although
three-membered ring compounds show higher-field chemical
shifts in the NMR spectra; for example, the 13C NMR chemical
shift of cyclopropane is ꢄ2:8 ppm while that of cyclobutane is
22.9 ppm.34
UV–Vis Spectra. Figure 1 shows the UV–vis spectra of
the five-membered ring compounds 3 and 6, both of which
showed three absorption maxima in the visible region. The pat-
tern of the UV–vis spectrum of the two compounds is similar,
which indicates that 3 and 6 have similar electronic structures.
In addition, the absorption maxima of the selenium congener 6
shifts to the longer wavelength region with smaller absorption
coefficients compared with those of the sulfur congener 3.
The UV–vis spectra of four-membered ring compounds 5
and 7 are shown in Fig. 2. The absorption maxima of 5 and
7 are observed around 400 nm, and also in this case, the ab-
sorption maximum in the UV–vis spectrum of 7 was observed
at longer wavelength region with a smaller absorption coeffi-
cient than those of the sulfur analog 5.
bitals of [Dmp2SiS3TiCp2] (30) and [Dmp2SiS2TiCp2] (50) are
depicted in Fig. 3. The TD-B3LYP calculations of 30 gave
three absorption maxima in visible region similar to the ob-
served UV–vis spectrum of 3. The observed absorption maxi-
ma at 417, 555, and 648 nm can be assigned to HOMOꢄ5 !
LUMO (Dmp ! Ti), HOMOꢄ1 ! LUMO (S3 (pz) ! Ti),
and HOMO ! LUMO (S3 (pz) ! Ti) transitions, respective-
ly. The observed UV–vis spectrum of 5 showed one absorption
maximum in visible region, while the TD-B3LYP calculations
of 50 indicated that there should be three absorption maxima
in visible region. This difference is due to the small f values
for the calculated absorptions at 652 ( f ¼ 0:0006) and 684
( f ¼ 0:0024) nm.
The calculated molecular orbitals of the selenium analogues
60 and 70 are almost the same as those of the sulfur analogues
30 and 50, respectively. The observed absorption maxima of 6
and 7 were assigned in a manner similar to the case of the
sulfur analogues 3 and 5 (Table 3).
In conclusion, novel silacyclic compounds containing a tita-
nium and some chalcogen atoms have been prepared by the
reactions of a bulky silylene (2) with titanocene pentachalco-
genide. The structures of the newly obtained silacyclic com-
pounds were determined by the spectroscopy and elemental
analysis, and the maxima in the UV–vis spectra were assigned
based on TD-B3LYP calculations.
To assign the absorption maxima, time-dependent density-
functional theory (TDDFT) calculations of model molecules
were performed. The observed and calculated absorption
maxima are listed in Table 3 and the calculated molecular or-

1576 Bull. Chem. Soc. Jpn. Vol. 79, No. 10 (2006)
Silacycles Containing Ti and S or Se Atoms
Wakogel C-200 and Merk Kieselgel 60 PF254, respectively. Gel
permeation liquid chromatography (GPLC) was performed on a
LC-908, LC-918, or LC-908-C60 (Japan Analytical Industry
Co., Ltd. Systems) equipped with JAIGEL 1H and 2H columns
(eluent: chloroform or toluene).
Preparation of Materials. Disilene 1,29 titanocene pentasul-
fide, and titanocene pentaselenide36 were prepared according to
the reported methods.
LUMO
LUMO
Preparation of [Tbt(Mes)SiS3TiCp2] (3). In a 10 ꢆ Pyrex
glass tube was placed a THF solution (2.0 mL) of a mixture of di-
silene 1 (40.0 mg, 28.6 mmol) and titanocene pentasulfide (19.4
mg, 57.2 mmol). After three freeze–pump–thaw cycles, the tube
was evacuated and sealed. The solution was heated at 60 ꢁC for
40 h, during which time the original orange suspension turned into
a deep black solution. The tube was opened, and the solvent was
removed under reduced pressure. After the addition of C6H6 to the
residue, the mixture was filtered through Celiteꢁ, and the solvent
was evaporated. The residue was separated by GPLC (toluene)
and then PTLC (hexane:Et2O = 2:1) to afford pure [Tbt(Mes)-
SiS3TiCp2] (3) (20.0 mg, 21.0 mmol, 36%). 3: dark green crystals,
HOMO
HOMO
1
mp 78 ꢁC (decomp); H NMR (300 MHz, C6D6) ꢂ 0.1–0.5 (54H),
1.52 (s, 1H), 2.06 (s, 3H), 2.48 (s, 3H), 2.71 (s, 2H), 3.50 (s, 3H),
5.82 (s, 5H), 6.05 (s, 5H), 6.59 (s, 1H), 6.67 (s, 1H), 6.77 (s, 1H),
7.01 (s, 1H); 13C NMR (75 MHz, C6D6) ꢂ 1.22 (q), 2.17 (q), 2.48
(q), 20.94 (q ꢅ 2), 25.93 (d), 27.42 (d), 29.35 (d), 30.92 (q),
114.88 (d), 115.54 (d), 123.32 (d), 128.18 (d), 129.07 (d), 130.68
(d), 137.17 (s), 138.47 (s), 138.79 (s), 143.81 (s), 144.12 (s),
144.98 (s), 153.9 (s ꢅ 2); 29Si NMR (59 MHz, C6D6) ꢂ ꢄ0:6, 1.8,
46.5; MS (FABþ): calcd for C46H80S3Si7Ti: 972, found: m=z 973
½M þ Hꢃþ, 907 ½M ꢄ Cpꢃþ, 875 ½M ꢄ Cp ꢄ Sꢃþ; HRMS (FABþ)
calcd for C46H81S3Si7Ti (½M þ Hꢃþ): 973.3365, found: m=z
973.3391 (½M þ Hꢃþ); UV–vis (hexane): ꢁmax 417 (" ¼ 3:2 ꢅ
103 (Mꢄ1 cmꢄ1)), 555 (" ¼ 1:3 ꢅ 103), 648 (" ¼ 1:2 ꢅ 103) nm.
Anal. Calcd for C46H80S3Si7Ti: C, 56.74; H, 8.28%. Found: C,
56.68; H, 8.27%.
HOMO−1
HOMO−1
HOMO−5
[Dmp2SiS3TiCp2] (3')
HOMO−3
[Dmp2SiS2TiCp2] (5')
Fig. 3. Molecular orbitals of 30 and 50.
Preparation of a Mixture of [Tbt(Mes)SiS3TiCp2] (3) and
[Tbt(Mes)SiS4TiCp2] (4). In a 10 ꢆ Pyrex glass tube was placed
a C6H6 solution (2.0 mL) of a mixture of disilene 1 (40.0 mg,
28.6 mmol) and titanocene pentasulfide (19.4 mg, 57.2 mmol). Af-
ter three freeze–pump–thaw cycles, the tube was evacuated and
sealed. The solution was heated at 60 ꢁC for 15 h, during which
time the original orange suspension turned into a deep black solu-
tion. The tube was opened, the solvent was removed under re-
duced pressure, and C6H6 was added to the residue. The mixture
was filtered through Celiteꢁ, and the filtrate was evaporated. The
residue was separated by GPLC (toluene) and PTLC (hexane:
Et2O = 2:1) to afford a mixture of [Tbt(Mes)SiS3TiCp2] (3)
and [Tbt(Mes)SiS4TiCp2] (4). Although the mixture of 3 and 4
could not be separated, the yields of these products were estimated
as 60 and 22%, respectively, based on the integrated intensity in
the 1H NMR spectrum. 4 (not isolated): 1H NMR (300 MHz,
C6D6) ꢂ 0.21 (s, 36H), 0.44 (s, 18H), 1.53 (s, 1H), 2.11 (s, 3H),
2.81 (s, 2H), 2.96 (s, 6H), 5.64 (s, 5H), 5.96 (s, 5H), 6.60 (s, 1H),
6.68 (s, 1H), 6.76 (s, 2H); 13C NMR (75 MHz, C6D6) ꢂ 1.17 (q),
2.16 (q), 2.48 (q), 20.92 (q), 27.18 (q), 27.40 (d), 29.31 (d),
31.90 (d), 113.98 (d), 114.46 (d), 123.93 (d), 129.53 (d), 130.34
(d), 133.91 (s), 139.05 (s), 140.50 (s), 143.88 (s), 144.62 (s),
144.99 (s), 145.56 (s); MS (FABþ) calcd for C46H80S4Si7Ti:
1004, found: m=z 1005 ½M þ Hꢃþ, 1004 [M]þ, 939 ½M ꢄ Cpꢃþ;
HRMS (FABþ) calcd for C46H81S4Si7Ti (½M þ Hꢃþ): 1005.3085,
found: m=z 1005.3129 (½M þ Hꢃþ).
Experimental
General Procedure. All experiments were performed under
anhydrous conditions and an argon atmosphere unless otherwise
noted. All solvents used in the reactions were purified prior to
use by the standard methods and/or by using an Ultimate Solvent
System (Glass Contour Company).35 C6D6, used as a reaction sol-
vent, was dried over Na, and then a K mirror. 1H NMR (300 MHz)
spectra were measured in C6D6 on a JEOL AL-300 spectrometer
using C6D5H (7.15 ppm) as an internal standard. 13C NMR (75
MHz) spectra were recorded on a JEOL JNM AL-300 spectrom-
eter. 13C NMR chemical shifts are reported as ppm downfield from
tetramethylsilane and were referenced to the signal of C6D6
(128.0 ppm). Multiplicity of signals in the 13C NMR spectra was
determined with the DEPT technique. 29Si NMR (59 MHz) and
77Se NMR (95 MHz) spectra were recorded on a JEOL JNM
AL-300 spectrometer. IR and electronic spectra were recorded on
a JASCO FT/IR-5300 spectrometer and a JASCO Ubest V-750
UV–vis spectrometer, respectively. Mass spectral data were ob-
tained on a JEOL JMS-700 spectrometer. Elemental analyses
were carried out at the Microanalytical Laboratory of Institute
for Chemical Research, Kyoto University. All melting points
were measured on a Yanaco micro melting points apparatus and
are uncorrected. Wet column chromatography (WCC) and prepa-
rative thin-layer chromatography (PTLC) were performed using
Reaction of [Tbt(Mes)SiS3TiCp2] (3) with an Equimolar

N. Takeda et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 10 (2006) 1577
Amount of Triphenylphosphine (Preparation of [Tbt(Mes)-
SiS2TiCp2] (5)). In a 5 ꢆ Pyrex glass tube was placed a C6D6
solution (0.5 mL) of a mixture of [Tbt(Mes)SiS3TiCp2] (3) (65.6
mg, 67.4 mmol) and triphenylphosphine (17.7 mg, 67.4 mmol). Af-
ter three freeze–pump–thaw cycles, the tube was evacuated and
sealed. The solution was heated at 60 ꢁC for 3 days, during which
time the original dark green color turned into orange color. The
tube was opened, and the solvent was removed under reduced
pressure in a glovebox filled with argon. Hexane was added to
the mixture containing [Tbt(Mes)SiS2TiCp2] (5) and triphenyl-
phosphine sulfide. The mixture was filtered through Celiteꢁ to re-
move triphenylphosphine sulfide, which is only slightly soluble in
hexane. Evaporation of the solvent from filtrate gave pure 5 (57.6
mg, 61.3 mmol, 91%). 5: orange solid; 1H NMR (300 MHz, C6D6)
ꢂ 0.23 (s, 18H), 0.34 (s, 18H), 0.42 (s, 18H), 1.53 (s, 1H), 2.11 (s,
3H), 3.06 (s, 6H), 3.23 (s, 1H), 3.69 (s, 1H), 5.85 (s, 5H), 6.30 (s,
5H), 6.63 (s, 1H), 6.71 (s, 1H), 6.83 (s, 2H); 13C NMR (75 MHz,
C6D6) ꢂ 1.38 (q), 2.48 (q), 2.56 (q), 20.94 (q), 26.56 (q), 27.97 (d),
28.16 (d), 30.73 (d), 119.42 (d), 120.01 (d), 124.80 (d), 128.56 (d),
130.46 (d), 130.53 (s), 138.03 (s), 140.33 (s), 143.50 (s), 144.80
(s), 153.28 (s), 153.89 (s); 29Si NMR (59 MHz, C6D6) ꢂ ꢄ52:7,
2.0, 2.6; MS (FABþ) calcd for C46H81S2Si7Ti: 940, found:
m=z 941 ½M þ Hꢃþ, 875 ½ðM ꢄ CpÞꢃþ; HRMS (FABþ) calcd
for C46H81S2Si7Ti (½M þ Hꢃþ): 941.3644, found: m=z 941.3681
(½M þ Hꢃþ); UV–vis (hexane): ꢁmax 372 (" ¼ 6 ꢅ 103) nm.
Reaction of a Mixture of [Tbt(Mes)SiS3TiCp2] (3) and
[Tbt(Mes)SiS4TiCp2] (4) with an Excess Amount of Triphen-
ylphosphine. In a 5 ꢆ Pyrex glass tube was placed a C6D6 solu-
tion (0.5 mL) of a mixture of [Tbt(Mes)SiS3TiCp2] (3) and
[Tbt(Mes)SiS4TiCp2] (4) (total 50 mg, with a ratio of 3:4 = 2:1)
and triphenylphosphine (60 mg, 228.5 mmol). After three freeze–
pump–thaw cycles, the tube was evacuated and sealed. When
the solution was heated at 60 ꢁC for 4 h, the original mixture of
3 and 4 converged to 3, and the formation of a 0.33 molar amount
of Ph3P=S was confirmed by 1H NMR spectroscopy. Further heat-
ing at 60 ꢁC for 4 days gave [Tbt(Mes)SiS2TiCp2] (5) quantita-
tively.
Reaction of [Tbt(Mes)SiS3TiCp2] (3) with an Excess
Amount of R3P (R ¼ Ph, n-Bu, Me2N, Me, and MeO). Except
for triphenylphosphine (solid) and trimethylphosphine, other triva-
lent phosphorus reagents were distilled from CaH2 or Na under an
argon atmosphere or reduced pressure. In a 5 ꢆ Pyrex glass tube
was placed a C6D6 solution (0.5 mL) of a mixture of [Tbt(Mes)-
SiS3TiCp2] (3) and an excess amount of a trivalent phosphorus
reagent. After three freeze–pump–thaw cycles, the tube was evac-
uated and sealed. The solution was left at room temperature or
heated. All of the reactions gave [Tbt(Mes)SiS2TiCp2] (5) quanti-
tatively together with an equimolar amount of the corresponding
phosphine sulfide.
Preparation of [Tbt(Mes)SiSe3TiCp2] (6). In a 10 ꢆ Pyrex
glass tube was placed a THF solution (2.0 mL) of a mixture of
disilene 1 (50.0 mg, 35.7 mmol) and titanocene pentaselenide
(41.0 mg, 71.6 mmol). After three freeze–pump–thaw cycles, the
tube was evacuated and sealed. The solution was heated at 60 ꢁC
for 15 h, during which time the original orange suspension turned
into a green solution. The tube was opened, and the solvent was
removed under reduced pressure in a glovebox filled with argon.
After the addition of C6H6 to the residue, the mixture was filtered
through Celiteꢁ, and the solvent was evaporated from the filtrate.
The residue was separated by PTLC (hexane, then benzene) to
afford pure [Tbt(Mes)SiSe3TiCp2] (6) (35.9 mg, 32.2 mmol, 45%)
as a green solid. 6: dark green crystals, mp 157 ꢁC (decomp);
1H NMR (300 MHz, C6D6) ꢂ ꢄ0:2{0:8 (54H), 1.51 (s, 1H), 2.10
(s, 3H), 2.51 (s, 3H), 2.60 (s, 1H), 2.62 (s, 1H), 3.61 (s, 3H),
5.83 (s, 5H), 6.02 (s, 5H), 6.5–6.8 (2H), 6.79 (s, 1H), 7.02 (s,
1H); 13C NMR (75 MHz, C6D6) ꢂ 1.34 (q), 1.37 (q), 2.61 (q),
2.72 (q), 20.94 (q), 26.95 (q), 28.36 (d), 28.63 (d), 30.74 (d),
119.21 (d), 119.81 (d), 124.84 (d), 130.25 (s), 132.94 (s),
133.08 (s), 137.94 (s), 139.14 (s), 143.59 (d), 144.59 (d), 153.45
(s), 154.27 (s); 29Si NMR (59 MHz, C6D6) ꢂ 2.2, 32.0; 77Se NMR
(95 MHz, C7D8, 60 ꢁC) ꢂ 407.5, 681.0, 1282.6; MS (FABþ) calcd
for C46H8078Se80Se2Si7Ti: 1114, found: m=z 1114 [M]þ, 1049
½M ꢄ Cpꢃþ; HRMS (FABþ) calcd for C46H8078Se80Se2Si7Ti
([M]þ): 1114.1628, found: m=z 1114.1649 [M]þ; UV–vis (hex-
ane): ꢁmax 442 (" ¼ 1:5 ꢅ 103), 598 (" ¼ 6:3 ꢅ 102), 740 (" ¼
4:7 ꢅ 102) nm.
Reaction of [Tbt(Mes)SiSe3TiCp2] (6) with an Equimolar
Amount of Triphenylphosphine (Preparation of [Tbt(Mes)-
SiSe2TiCp2] (7)). In a 5 ꢆ Pyrex glass tube was placed a C6D6
solution (0.5 mL) of a mixture of [Tbt(Mes)SiSe3TiCp2] (6) (63.6
mg, 57.3 mmol) and triphenylphosphine (15.0 mg, 57.3 mmol). Af-
ter three freeze–pump–thaw cycles, the tube was evacuated and
sealed. The mixture was stirred for 30 min, during which time
the original green color turned into dark yellow color. The
1H NMR spectrum of the reaction mixture showed the quantitative
formation of [Tbt(Mes)SiSe2TiCp2] (7) and triphenylphosphine
selenide. The tube was opened in a glovebox filled with argon,
and the solvent was removed under reduced pressure. After the ad-
dition of hexane to the residue, the mixture was filtered through
Celiteꢁ to remove triphenylphosphine selenide. The filtrate was
evaporated to give pure compound 7 (56.4 mg, 54.4 mmol, 95%).
1
7: yellow solid; H NMR (300 MHz, C6D6) ꢂ 0.22 (s, 18H), 0.36
(s, 18H), 0.44 (s, 18H), 1.51 (s, 1H), 2.13 (s, 3H), 3.14 (s, 6H),
3.23 (s, 1H), 3.64 (s, 1H), 5.97 (s, 5H), 6.31 (s, 5H), 6.63 (s, 1H),
6.73 (s, 1H), 6.85 (s, 2H); 13C NMR (75 MHz, C6D6) ꢂ 1.34 (q),
1.37 (q), 2.61 (q), 2.72 (q), 20.94 (q), 26.95 (q), 28.36 (d), 28.63
(d), 30.74 (d), 119.21 (d), 119.81 (d), 124.84 (d), 130.25 (s),
132.94 (s), 133.08 (s), 137.94 (s), 139.14 (s), 143.59 (d), 144.59
(d), 153.45 (s), 154.27 (s); 29Si NMR (59 MHz, C6D6) ꢂ ꢄ57:2,
2.1, 2.6; MS (FABþ) calcd for C46H8080Se2Si7Ti: 1036, found:
m=z 1036 [M]þ, 971 ½ðM ꢄ CpÞꢃþ; HRMS (FABþ) calcd for
C46H8080Se2Si7Ti ([M]þ): 1036.2455, found: m=z 1036.2466
([M]þ); UV–vis (hexane) ꢁmax 418 (" ¼ 2:0 ꢅ 103).
Reaction of [Tbt(Mes)SiSe3TiCp2] (6) with an Excess
Amount of R3P (R ¼ Ph, Bu, Me2N, and Me). Except for tri-
phenylphosphine (solid) and trimethylphosphine, other trivalent
phosphorus reagents were all distilled from CaH2 or Na under
an argon atmosphere or reduced pressure. In a 5 ꢆ Pyrex glass
tube was placed a C6D6 solution (0.5 mL) of a mixture of [Tbt-
(Mes)SiSe3TiCp2] (6) and an excess amount of a trivalent phos-
phorus reagent. After three freeze–pump–thaw cycles, the tube
was evacuated and sealed. In all cases, the reaction immediately
proceeded at room temperature to give quantitatively [Tbt(Mes)-
SiSe2TiCp2] (7) together with an equimolar amount of the corre-
sponding phosphine selenide.
Photoreaction of a Mixture of [Tbt(Mes)SiSe2TiCp2] (7)
and Hexamethylphosphorous Triamide (HMPT). In a 5 ꢆ
Pyrex glass tube was placed a C6D6 solution (0.5 mL) of [Tbt-
(Mes)SiSe2TiCp2] (7) (36.4 mg, 32.7 mmol). HMPT (53.4 mL,
294.3 mmol), distilled from CaH2, was added to the solution. After
three freeze–pump–thaw cycles, the tube was evacuated and
sealed. Heating of the solution at 100 ꢁC for 3 h resulted in no re-
action. The solution was irradiated (ꢁ ¼ 300{500 nm) using a Xe
lamp through a UV cut filter (HOYA colored optical glass B390,

1578 Bull. Chem. Soc. Jpn. Vol. 79, No. 10 (2006)
Silacycles Containing Ti and S or Se Atoms
300 < ꢁ < 500 nm transfer). No reaction occurred, even after
irradiation for 15 h. Further irradiation resulted in the formation
of a complicated mixture.
7
1331.
8
H.-C. Liang, P. A. Shapley, Organometallics 1996, 15,
P. A. Shapley, H.-C. Liang, N. C. Dopke, Organometallics
X-ray Crystallography of [Tbt(Mes)SiSe3TiCp2] (6). Crys-
tals used in X-ray structural analysis of 6 were grown from hexane
at room temperature. Intensity data were collected on a Rigaku/
MSC Mercury CCD diffractometer with graphite monochromator
2001, 20, 4700.
9 T. Komuro, T. Matsuo, H. Kawaguchi, K. Tatsumi, Inorg.
Chem. 2003, 42, 5340.
10 T. Komuro, T. Matsuo, H. Kawaguchi, K. Tatsumi, Chem.
Commun. 2002, 988.
11 J. Albertsen, R. Steudel, J. Organomet. Chem. 1992, 424,
153.
˚
Mo Kꢃ radiation (ꢁ ¼ 0:71070 A). The structure was solved by
using direct methods (SIR-97)37 and refined by full-matrix least-
squares procedures on F2 for all reflections (SHELXL-97).38 All
of the non-hydrogen atoms were refined with anisotropic thermal
parameters. All hydrogen atoms were placed in calculated posi-
12 D. M. Giolando, T. B. Rauchfuss, Inorg. Chem. 1987, 26,
3080.
tions. 6: green crystals; formula C46H80Se3Si7Ti 0.5(C6H14), MW
ꢆ
13 D. Seyferth, R. S. Henderson, L.-C. Song, Organometallics
1982, 1, 125.
14 D. Seyferth, R. S. Henderson, L.-C. Song, J. Organomet.
Chem. 1980, 192, C1.
15 N. Choi, S. Morino, S. Sugi, W. Ando, Bull. Chem. Soc.
Jpn. 1996, 69, 1613.
16 H. G. Raubenheimer, S. Lotz, G. J. Kruger, A. v. A.
Lombard, J. C. Viljoen, J. Organomet. Chem. 1987, 336, 349.
17 D. M. Gioland, T. B. Rauchfuss, Organometallics 1984, 3,
487.
18 N. Tokitoh, R. Okazaki, Adv. Organomet. Chem. 2001, 47,
121.
19 R. Okazaki, N. Tokitoh, Acc. Chem. Res. 2000, 33, 625.
20 M. Saito, N. Tokitoh, R. Okazaki, J. Am. Chem. Soc. 1997,
119, 11124.
21 N. Tokitoh, N. Kano, K. Shibata, R. Okazaki, Organo-
metallics 1995, 14, 3121.
22 T. Matsumoto, N. Tokitoh, R. Okazaki, M. Goto, Organo-
metallics 1995, 14, 1008.
23 Y. Matsuhashi, N. Tokitoh, R. Okazaki, M. Goto, S.
Nagase, Organometallics 1993, 12, 1351.
24 N. Tokitoh, H. Suzuki, T. Matsumoto, Y. Matsuhashi,
R. Okazaki, M. Goto, J. Am. Chem. Soc. 1991, 113, 7047.
25 N. Tokitoh, Y. Arai, J. Harada, R. Okazaki, Chem. Lett.
1995, 959.
26 N. Tokitoh, J. Organomet. Chem. 2000, 611, 217.
27 N. Tokitoh, Acc. Chem. Res. 2004, 37, 86.
28 H. Suzuki, N. Tokitoh, J. Harada, K. Ogawa, S. Tomoda,
M. Goto, Organometallics 1995, 14, 1016.
29 H. Suzuki, N. Tokitoh, R. Okazaki, Bull. Chem. Soc. Jpn.
1995, 68, 2471.
30 N. Tokitoh, H. Suzuki, R. Okazaki, K. Ogawa, J. Am.
Chem. Soc. 1993, 115, 10428.
31 H. Suzuki, N. Tokitoh, R. Okazaki, S. Nagase, M. Goto,
J. Am. Chem. Soc. 1998, 120, 11096.
32 C. M. Bolinger, J. E. Hoots, T. B. Rauchfuss, Organo-
metallics 1982, 1, 223.
33 C. M. Bolinger, T. B. Rauchfuss, Inorg. Chem. 1982, 21,
3947.
˚
ꢁ
1157.57; monoclinic; space group P21=a (#14); a ¼ 24:815ð4Þ A,
ꢁ
˚
˚
b ¼ 9:4770ð13Þ A, c ¼ 25:627ð5Þ A; ꢃ ¼ 90 , ꢄ ¼ 94:030ð8Þ ,
ꢁ
3
ꢅ ¼ 90 ; V ¼ 6011:8ð16Þ A ; Z ¼ 4; ꢀ ¼ 3:404 mmꢄ1; Dcalcd
¼
˚
1:468 Mg mꢄ3; 2ꢇmax ¼ 50:0ꢁ; T ¼ 103ð2Þ K; R1 ðI > 2ꢈðIÞÞ ¼
0:1284; wR2 (all data) = 0.4325; GOF ¼ 1:005 for 8254 reflec-
tions and 535 parameters.
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre: Deposition number CCDC-607936
for compound 6. Copies of the data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge, CB2 1EZ, UK; Fax: +44 1223 336033; e-mail: deposit@
ccdc.cam.ac.uk).
Computational Methods. The geometries of [Dmp2SiS3-
TiCp2] (30), [Dmp2SiS2TiCp2] (50), [Dmp2SiSe3TiCp2] (60), and
[Dmp2SiSe2TiCp2] (70) were optimized by using the Gaussian
98 program39 using the B3LYP/6-31G(d) basis set. The GIAO-
B3LYP calculations were carried out with 6-311G(2d,p) for Si
and 6-311G(d) for C and H as basis sets, and the TD-B3LYP
calculations were carried out with 6-31G(d) basis sets.
This work was supported in part by Grants-in-Aid for COE
Research on Elements Science (No. 12CE2005), Creative Sci-
entific Research (No. 17GS0207), Scientific Research on Prior-
ity Area (No. 14078213), Young Scientist (B) (No. 15750031),
and the 21st Century COE Program on Kyoto University Alli-
ance for Chemistry, from the Ministry of Education, Culture,
Sports, Science and Technology, Japan. We are grateful to
Assistant Professor Takahiro Sasamori, Institute for Chemical
Research, Kyoto University, for the valuable discussions.
Supporting Information
Atomic coordinates for the calculated molecules 30, 50, 60, and
1
70 and the H and 13C NMR spectra of 3, 5, 6, and 7. These ma-
terials are available free of charge on the web at http://www.csj.
jp/journals/bcsj/.
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