Insertion of pyridine into an iron-silicon bond and photochemical conversion of the insertion product Cp*(OC)Fe{η3(C,C,C)- C5H5NSiMe2NPh2} to a sandwich compound

Article abstract of DOI:10.1021/om060873n

Irradiation of Cp*(OC)₂FeSiMe₂ER_n (ER_n = NPh₂, NMe₂, OMe) in the presence of pyridine affords Cp*(OC)(C₅H₅N)FeSiMe ₂ER_n, which are converted to Cp*(OC) Fe{η³(C,C,C)-C₅H₅NSiMe₂ER _n} upon mild heating via insertion of pyridine into the iron-silicon bond. This type of pyridine insertion does not proceed in the thermal reactions of Cp*(OC)(C₅H₅N)FeSiMe₂R (R = Cl, Me) and the germanium analogues, Cp*(OC)(C₅H₅N) FeGeMe₂ER_n (ER_n = NPh₂, NMe ₂, Me), even under more severe conditions. Treatment of Cp*(OC)(C₅H₅N)RuMe with HSiMe₂NPh ₂ at room temperature gives a 5:4 equilibrium mixture of Cp*(OC)(C₅H₅N)RuSiMe₂NPh₂ and Cp*(OC)HRu{κ²(Si,C)-SiMe₂N(o-C ₆H₄)(Ph)}. Heating the mixture at 100°C does not afford an analogous insertion product, although the equilibrium is shifted to the side of the orthometalated compound. These results indicate that the insertion of pyridine is specific for the heteroatom-substituted silyliron(II) system. The insertion reaction is considered to proceed via the mechanism that involves the initial formation of an η²(N,C)-pyridine complex. Migratory insertion of pyridine into the iron-silicon bond accompanied by coordination of the terminal heteroatom then results in a congested transition state, leading to the formation of an η¹-allyl intermediate, Cp*(OC)Fe-{κ²(C,E)-C₅H₅NSiMe ₂ER₂}. The formation of such a transition state is supported by kinetic analysis of the thermal conversion of Cp*(OC)(C ₅H₅N)FeSiMe₂NPh₂ to Cp*(OC)Fe{η³(C,C,C)-C₅H₅NSiMe ₂NPh₂}, giving activation parameters of ΔH* = 93(2) kJ mol^-1, ΔS? = -53(6) J mol^-1 K ^-1, and ΔG?_{298 K} = 109(3) kJ mol ^-1. The η³-allyl complex is finally formed through dissociation of the amino part. Irradiation of Cp*(OC) Fe{η³(C,C,C)-C₅H₅NSiMe₂NPh ₂} causes dissociation of a carbonyl ligand to produce a new type of sandwich compound, Cp*Fe(η⁵-C₅H ₅NSiMe₂NPh₂).

Full text of DOI:10.1021/om060873n

Organometallics 2006, 25, 6115-6124
6115
Insertion of Pyridine into an Iron-Silicon Bond and Photochemical
Conversion of the Insertion Product
Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NPh2} to a Sandwich Compound
Masatoshi Iwata, Masaaki Okazaki,*,† and Hiromi Tobita*
Department of Chemistry, Graduate School of Science, Tohoku UniVersity, Sendai 980-8578, Japan
ReceiVed September 25, 2006
Irradiation of Cp*(OC)2FeSiMe2ERn (ERn ) NPh2, NMe2, OMe) in the presence of pyridine affords
Cp*(OC)(C5H5N)FeSiMe2ERn, which are converted to Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2ERn} upon
mild heating via insertion of pyridine into the iron-silicon bond. This type of pyridine insertion does
not proceed in the thermal reactions of Cp*(OC)(C5H5N)FeSiMe2R (R ) Cl, Me) and the germanium
analogues, Cp*(OC)(C5H5N)FeGeMe2ERn (ERn ) NPh2, NMe2, Me), even under more severe conditions.
Treatment of Cp*(OC)(C5H5N)RuMe with HSiMe2NPh2 at room temperature gives a 5:4 equilibrium
mixture of Cp*(OC)(C5H5N)RuSiMe2NPh2 and Cp*(OC)HRu{κ2(Si,C)-SiMe2N(o-C6H4)(Ph)}. Heating
the mixture at 100 °C does not afford an analogous insertion product, although the equilibrium is shifted
to the side of the orthometalated compound. These results indicate that the insertion of pyridine is specific
for the heteroatom-substituted silyliron(II) system. The insertion reaction is considered to proceed via
the mechanism that involves the initial formation of an η2(N,C)-pyridine complex. Migratory insertion
of pyridine into the iron-silicon bond accompanied by coordination of the terminal heteroatom then
results in a congested transition state, leading to the formation of an η1-allyl intermediate, Cp*(OC)Fe-
{κ2(C,E)-C5H5NSiMe2ER2}. The formation of such a transition state is supported by kinetic analysis of
the thermal conversion of Cp*(OC)(C5H5N)FeSiMe2NPh2 to Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NPh2},
giving activation parameters of ∆Hq ) 93(2) kJ mol-1, ∆Sq ) -53(6) J mol-1 K-1, and ∆Gq
)
298
K
109(3) kJ mol-1. The η3-allyl complex is finally formed through dissociation of the amino part. Irradiation
of Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NPh2} causes dissociation of a carbonyl ligand to produce a new
type of sandwich compound, Cp*Fe(η5-C5H5NSiMe2NPh2).
metal-silicon bond is a crucial step in the catalytic hydrosily-
lation of alkene.4,5 The reactions of various isolated transition-
metal silyl complexes with unsaturated organic molecules have
thus been investigated in an attempt to gain insight into this
catalytic hydrosilylation mechanism.6 Although there are numer-
ous examples of the insertion of alkenes, alkynes, nitriles, and
carbonyl compounds into metal-silicon bonds, little is known
regarding the insertion of aromatic compounds into these bonds.
Research on this type of stoichiometric reaction could stimulate
the development of the little-explored transition-metal-catalyzed
hydrosilylation of aromatic compounds. Woo and Tilley ob-
served the insertion of pyridine into the zirconium-silicon bond
in the reaction of CpCp*Zr[Si(SiMe3)3]Me and pyridine to
afford CpCp*Zr[κ1(N)-NC5H5Si(SiMe3)3]Me, in which the re-
giospecificity is different from the intermediate in the Cp2TiMe2-
catalyzed hydrosilylation of pyridine.7 We herein report the
insertion of pyridine into an iron-silicon bond by the thermal
Introduction
The hydrosilylation of unsaturated organic compounds is one
of the most important reactions in organosilicon chemistry and
has been examined thoroughly and extensively for application
in the industrial production of organosilicon compounds. In
research laboratories, hydrosilylation of unsaturated organic
compounds provides not only synthetic intermediates in organic
syntheses but also silicon-based new materials.1 However, the
scope of the hydrosilylation of aromatic compounds is extremely
narrow. Pyridine is the only example of an aromatic substrate
that has been successfully hydrosilylated. Heterogeneous cata-
lytic hydrosilylation of pyridines was achieved by Cook and
Lyons many years ago.2 In 1998, Harrod et al. reported for the
first time the homogeneously catalyzed hydrosilylation of
pyridines, mixing PhMeSiH2 and pyridine in the presence of
Cp2TiMe2 to produce N-silyl-2,3,4-trihydropyridine accompa-
nied by the formation of (PhMeHSi)n.3
In the modified Chalk-Harrod mechanism, first proposed by
Seitz and Wrighton, the insertion of an alkene molecule into a
(4) (a) Schroeder, M. A.; Wrighton, M. S. J. Organomet. Chem. 1977,
128, 345-358. (b) Reichel, C. L.; Wrighton, M. S. Inorg. Chem. 1980, 19,
3858-3860. (c) Randolph, C. L.; Wrighton, M. S. J. Am. Chem. Soc. 1986,
108, 3366-3374. (d) Seitz, F.; Wrighton, M. S. Angew. Chem., Int. Ed.
Engl. 1988, 27, 289-291.
* To whom correspendence should be addressed. E-mail: mokazaki@
scl.kyoto-u.ac.jp (M.O.); tobita@mail.tains.tohoku.ac.jp (H.T.).
† Present address: International Research Center for Elements Science
(IRCELS), Institute for Chemical Research, Kyoto University.
(1) Ojima, I.; Li, Z.; Zhu, J. In The Chemistry of Organic Silicon
Compounds; Rappoport, Z., Apeloig, Y., Eds.; Wiley: New York, 1998;
Vol. 2, Chapter 35, pp 1687-1792.
(2) Cook, N. C.; Lyons, J. E. J. Am. Chem. Soc. 1966, 88, 3396-3403.
(3) (a) Hao, L.; Harrod, J. F.: Lebuis, A.-M.; Mu, Y.; Shu, R.; Samuel,
E.; Woo, H.-G. Angew. Chem. Int. Ed. 1998, 37, 3126-3129. (b) Harrod,
J. F.; Shu, R.; Woo, H.-G.; Samuel, E. Can. J. Chem. 2001, 79, 1075-
1085.
(5) Sakaki, S.; Sumimoto, M.; Fukuhara, M.; Sugimoto, M.; Fujimoto,
H.; Matsuzaki, S. Organometallics 2002, 21, 3788-3802.
(6) (a) Eisen, M. S. In The Chemistry of Organic Silicon Compounds;
Rappoport Z., Apeloig, Y., Eds.; Wiley: New York, 1998; Vol. 2, Chapter
35, pp 2037-2128. (b) Tilley, T. D. In The Silicon-Heteroatom Bond; Patai,
S., Rappoport, Z., Eds.; Wiley: New York, 1991; Chapters 9, 10, pp 245-
308, pp 309-364. (c) Braunstein, P.; Knorr, M. J. Organomet. Chem. 1995,
500, 21-38.
(7) Woo, H.-G.; Tilley, T. D. J. Organomet. Chem. 1990, 393, C6-C9.
10.1021/om060873n CCC: $33.50 © 2006 American Chemical Society
Publication on Web 11/17/2006

6116 Organometallics, Vol. 25, No. 26, 2006
Iwata et al.
reaction of Cp*(OC)(C5H5N)FeSiMe2NPh2 to give Cp*(OC)-
Fe{η3(C,C,C)-C5H5NSiMe2NPh2}. In this product, the silicon
atom is bound to the pyridine nitrogen atom, while the iron
atom is bound to the carbon atom. The product thus corresponds
to the proposed intermediate in the catalytic reaction. To
elucidate the essential requirements for the insertion step,
thermal reactions of Cp*(OC)(C5H5N)FeER3 (ER3 ) SiMe2-
NMe2, SiMe2Cl, SiMe3, SiMe2OMe, GeMe2NPh2, GeMe2NMe2,
and GeMe3) and selected ruthenium analogues are examined.
Irradiation of the insertion product affords an unprecedented
sandwich compound, Cp*Fe(η5-C5H5NSiMe2NPh2), which is
unequivocally determined by X-ray diffraction study. Some of
the results reported here have appeared elsewhere in a prelimi-
nary form.8
Figure 1. ORTEP drawing of 2a with thermal ellipsoids at the
50% probability level. Selected bond distances (Å) and angles
(deg): Fe-Si 2.3330(4), Fe-N2 1.991(1), Fe-C15 1.716(2), Si-
N1 1.799(1), O-C15 1.168(2), Si-Fe-N2 92.84(4), Si-Fe-C15
80.97(5), N2-Fe-C15 97.20 (6), Fe-Si-N1 118.70(5).
Results and Discussion
The synthesis of the aminosilyliron(II) complexes Cp*-
(OC)2FeSiMe2NR2 (R ) Ph (1a) and Me (1b)) by irradiation
of Cp*(OC)2FeMe and HSiMe2NPh2 or treatment of Li[Cp*-
(OC)2Fe] with ClSiMe2NMe2 in diethyl ether was presented in
a previous paper.9 Ultraviolet (UV) irradiation of 1a in the
presence of pyridine in toluene caused the solution to turn from
yellow to dark red in color (eq 1). Removal of volatiles followed
by recrystallization of the residue from toluene/hexane solution
at -30 °C gave dark red crystals of Cp*(OC)(C5H5N)FeSiMe2-
NPh2 (2a) in 72% yield. The NMe2 analogue Cp*(OC)-
(C5H5N)FeSiMe2NMe2 (2b) was synthesized similarly in 61%
yield by photoreaction between Cp*(OC)2FeSiMe2NMe2 (1b)
and pyridine. All spectroscopic data are in good agreement with
the structures of 2. The 29Si{1H} nuclear magnetic resonance
(NMR) signals of 2 were observed at δ 53.5 (2a) and 56.9 (2b).
Substitution of CO by the electron-releasing pyridine ligand
caused a significant shift of νCO to lower energies (1a, 1973,
1917 cm-1; 1b, 1971, 1911 cm-1; 2a, 1878 cm-1; 2b, 1869
cm-1).
Complex 2a can be regarded as a key intermediate in the
transition-metal-catalyzed hydrosilylation of pyridine. If the
reaction is operative, the pyridine N-C unsaturated bond would
be inserted into the Fe-Si bond. The feasibility of this reaction
was examined by carrying out the thermal reaction of 2a as
follows. A toluene solution of 2a was heated at 60 °C for 2
days (eq 2), after which volatiles were removed in vacuo and
the residue was extracted with pentane. Recrystallization of the
concentrated pentane extract at -30 °C gave orange crystals of
Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NPh2} (3a) in 55% yield.
The thermal reaction of 2b was performed under the same
conditions to afford Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NMe2}
(3b) in 86% NMR yield. However, 3b was an air-sensitive oil
and isolation was not successful. Characterization of 3b was
performed by comparison with the NMR spectra of 3a (vide
infra).
The structure of 3a was unequivocally determined by the
X-ray diffraction study. An ORTEP drawing of 3a is shown in
Figure 2. The complex has one Cp* and one CO ligand, and an
η3-allyl fragment formed through the insertion of pyridine into
the iron-silicon bond, in which the aminosilyl group is bound
to the nitrogen atom of pyridine. The geometry of complex 3
is thus the same as that suggested for the intermediate in the
catalytic hydrosilylation of pyridine by Cp2TiMe2.3 The dis-
tances of the Si-N1 and Si-N2 bonds are 1.747(2) and 1.742-
(2) Å, respectively, falling within the normal range for single
silicon-nitrogen bonds. The bonding parameters are also in the
range expected for the η3-allyl iron complexes:11 the carbon-
carbon bond distances in the allylic moiety are 1.413(4) Å
(C15-C16) and 1.412(4) Å (C16-C17). The distances between
iron and allylic carbon atoms are 2.134(3) Å (Fe-C15), 1.995-
(3) Å (Fe-C16), and 2.141(3) Å (Fe-C17), and the bond
lengths of C17-C18 and C18-C19 are 1.471(4) and 1.332(4)
Å, respectively, which corresponds to the values for the single
The molecular structure of 2a is depicted in Figure 1.
Complex 2a takes a typical three-legged piano-stool geometry
in which one carbonyl ligand in 1a is replaced with pyridine.
The Fe-Si bond distance (2.3330(4) Å) for 2a is shorter than
that in 1a (2.3355(7) Å), while the Si-N1 bond distance (1.799-
(1) Å) is longer than that in 1a (1.787(2) Å).9 These structural
features are attributable to the electron-rich iron center upon
coordination of the electron-releasing pyridine ligand, which
enhances back-donation from the iron dπ orbital to the Si-N
σ* orbital.10 The electron-richness is also reflected in the
elongation of the O-C15 bond (1.168(2) Å) compared to those
in 1a (1.159(3), 1.151(4) Å).
(8) Iwata, M.; Okazaki, M.; Tobita, H. Chem. Commun. 2003, 2744-
2745.
(9) Okazaki, M.; Iwata, M.; Tobita, H.; Ogino, H. Dalton Trans. 2003,
1114-1120.
(10) (a) Schilling, B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J. Am.
Chem. Soc. 1979, 101, 585-591. (b) Lichtenberger, D. L.; Rai-Chaudhuri,
A. J. Am. Chem. Soc. 1991, 113, 2923-2930. (c) Hu¨bler, K.; Hunt, P. A.;
M. Maddock, S.; Rickard, C. E. F.; Roper, W. R.; Salter, D. M.;
Schwerdtfeger, P.; Wright, L. J. Organometallics 1997, 16, 5076-5083.
(11) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1-S83.

Insertion of Pyridine into an Iron-Silicon Bond
Organometallics, Vol. 25, No. 26, 2006 6117
pyridine moiety in 3e were observed at δ (1H) 1.79 (2), 3.70
(3), 5.21 (4), 5.32 (5), and 5.62 (1) and δ (13C) 45.5 (2), 51.0
(3), 77.9 (1), 110.3 (4), and 121.5 (5), respectively. The 29Si
NMR signal was observed at δ 2.2. These NMR spectroscopic
features are quite similar to those for 3a and 3b. The reactivity
of 2a-e toward the insertion of pyridine decreased in the order
2a, 2b (reacted quantitatively) > 2e (reacted slowly and in low
yield) > 2c, 2d (no reaction).
To elucidate the critical factor driving the migratory insertion
of pyridine, the thermal reactions of germyl(pyridine) complexes
were also examined. Germyl complexes of the type Cp*-
(OC)2FeGeMe2R (R ) NPh2 (1f), NMe2 (1g), Me (1h)) were
synthesized by reaction of K[Cp*(OC)2Fe] with the correspond-
ing germanium halides (Scheme 2). Substitution of one carbonyl
ligand with pyridine to give Cp*(OC)(C5H5N)FeGeMe2R (R
) NPh2 (2f), NMe2 (2g), Me (2h)) was achieved by UV
irradiation of the complexes in the presence of pyridine. Thermal
conversion of 2f-h to the η3-allyl complexes, Cp*(OC)Fe{η3-
(C,C,C)-C5H5NGeMe2R}, did not take place at 60 °C. Under
more forced conditions of 110 °C, 2f-h decomposed to yield
several unidentified products.
Kinetic study of the thermal conversion from 2a to 3a in
benzene-d6 was conducted over the temperature range 328-
348 K to obtain plots of ln(At/A0) (A ) [2a]) with respect to
time t and the first-order rate constants. An Eyring plot gives
activation parameters of ∆Hq ) 93(2) kJ mol-1, ∆Sq ) -53(6)
J mol-1 K-1, and ∆Gq298 K ) 109(3) kJ mol-1 (see Supporting
Information). The relatively large negative ∆Sq value indicates
the existence of a sterically more congested transition state than
2a.
Figure 2. ORTEP drawing of 3a with thermal ellipsoids at the
50% probability level. Selected bond distances (Å) and angles
(deg): Fe-C15 2.134(3), Fe-C16 1.995(3), Fe-C17 2.141(3), Fe-
C20 1.730(3), C20-O 1.161(4), Si-N1 1.747(2), Si-N2 1.742-
(2), N2-C15 1.442(3), N2-C19 1.390(3), C15-C16 1.413(4),
C16-C17 1.412(4), C17-C18 1.471(4), C18-C19 1.332(4), Si-
N2-C15 118.0(2), Si-N2-C19 125.0(2), C15-N2-C19 116.3-
(2).
and double bond. The structurally related molybdenum com-
plexes with an η3-allyl ligand have been synthesized by
Malinakova and Liebeskind by a very different approach.12
The structures of 3 are also supported by the spectroscopic
A plausible formation mechanism for 3 involving initial
formation of an η2(N,C)-pyridine complex A is illustrated in
Scheme 3. The migratory insertion of pyridine into the iron-
silicon bond, accompanied by coordination of the terminal amino
group, results in the transition state B, leading to the formation
of an η1-allyl amino-coordinated complex C. Finally, C isomer-
izes to the η3-allyl complex 3 through dissociation of the amino
part.
1
data in solution. The H and 13C NMR signals of the inserted
pyridine moiety for 3a were observed at δ (1H) 1.77 (2), 3.74
(3), 5.30 (4), 5.47 (5), and 5.73 (1) and δ (13C) 45.1 (2), 51.2
(3), 76.9 (1), 110.8 (4), and 121.1 (5), respectively, where values
in parentheses denote the positions of the atoms (eq 2).
Assignments were established on the basis of two-dimensional
1H-1H and 13C-1H COSY spectral data. The chemical shifts
are consistent with the η3-allyl-type coordination of the
C5H5N(SiMe2NPh2) fragment. Both the X-ray and NMR data
thus clearly indicate that the aromaticity of the pyridine moiety
of 3 is disrupted. The 29Si NMR signal at δ -2.3 for 3a is shifted
toward the high-field region compared with that in 2a (δ 53.5),
supporting migration of the aminosilyl ligand from the iron
In 2, the coordination of electron-releasing Cp*, pyridine,
and aminosilyl ligands results in an extremely electron-rich iron
center. This type of an electronic factor may facilitate isomer-
ization of 2 to an κ2(N,C)-pyridine complex (i.e., A). The
electron density of the iron center is roughly estimated from
the wave number of νCO to decrease in the order 2b (1869 cm-1
)
> 2d, 2e (1873 cm-1) > 2h (1876 cm-1) > 2g (1877 cm-1) >
2a (1878 cm-1) > 2c (1882 cm-1) > 2f (1888 cm-1). As the
tendency for insertion of pyridine into the iron-silicon or iron-
germanium bond does not correlate with the electron-richness
of the iron center, transformation of 2 to A does not appear to
be a rate-determining step. On the other hand, the existence of
an amino or methoxy group capable of coordination to the
coordinatively unsaturated iron center appears to be crucial,
lowering the activation barrier for the insertion of pyridine into
the iron-silicon bond. Coordination of the Si-OR13 or Si-
NR214 group to metals has been well documented. This scenario
is supported by the kinetic study, which suggested a large
negative value of ∆Sq consistent with the transient generation
of the sterically congested form B.
center to the nitrogen atom. The CO vibration of 3a (1911 cm-1
)
now appears in the higher energy region compared to that of
the starting material 2a (1878 cm-1), supporting the replacement
of silyl and pyridine ligands with an η3-allyl ligand.
Thermal reactions were also attempted for selected silyl-
(pyridine)iron complexes of the type Cp*(OC)(C5H5N)FeSiMe2R
(R ) Cl (2c), Me (2d), and OMe (2e)) (Scheme 1). Under the
same conditions as described by eq 2, however, no reaction took
place. Thermolysis of 2c and 2d under more forced conditions
resulted in decomposition of the complexes. Reaction of 2e at
90 °C for 24 h gave the pyridine-inserted product Cp*(OC)-
Fe{η3(C,C,C)-C5H5NSiMe2OMe} (3e) in 18% NMR yield
together with Me2Si(OMe)2 (24%), unidentified products, and
recovered 2e (9%). Purification of 3e has yet to be achieved.
Complex 3e was characterized by comparison with the NMR
data of 3a and 3b. The 1H and 13C NMR signals of the inserted
(13) (a) Atagi, L. M.; Mayer, J. M. Organometallics 1994, 13, 4794-
4803. (b) Klei, S. R.; Tilley, T. D.; Bergman, R. G. Organometallics 2002,
21, 4648-4661. (c) Sakaba, H.; Watanabe, S.; Kabuto, C.; Kabuto, K. J.
Am. Chem. Soc. 2003, 125, 2842-2843.
(12) (a) Malinakova, H. C.; Liebeskind, L. S. Org. Lett. 2000, 2, 3909-
3911. (b) Malinakova, H. C.; Liebeskind, L. S. Org. Lett. 2000, 2, 4083-
4086. (c) Zhang, Y.; Liebeskind, L. S. J. Am. Chem. Soc. 2006, 128, 465-
472.
(14) (a) Aslanidis, P.; Grobe, J. J. Organomet. Chem. 1983, 249, 103-
126. (b) Schwarz, M.; Kickelbick, G.; Schubert, U. Eur. J. Inorg. Chem.
2000, 1811-1817. (c) Do¨hring, A.; Go¨hre, J.; Jolly, P. W.; Kryger, B.;
Rust, J.; Verhovnik, G. P. J. Organometallics 2000, 19, 388-402.

6118 Organometallics, Vol. 25, No. 26, 2006
Iwata et al.
Scheme 1
Scheme 2
The possibility of pyridine insertion into the ruthenium-
silicon bond by the same approach was also investigated.
Treatment of Cp*(OC)(C5H5N)RuMe with HSiMe2NPh2 at
room temperature gave a mixture of Cp*(OC)(C5H5N)RuSiMe2-
NPh2 (2i) and Cp*(OC)HRu{κ2(Si,C)-SiMe2N(o-C6H4)(Ph)} (4i)
in a 5:4 molar ratio. Recrystallization from toluene/pentane at
-30 °C afforded a mixture of 2i (29%) and 4i (31%) as orange
and light yellow crystals, respectively. The two crystal types
were successfully separated on the basis of color. To avoid
formation of the orthometalated 4i, the reaction of Cp*(OC)-
(C5H5N)RuMe with HSiMe2NPh2 was carried out in the
presence of excess pyridine, requiring more severe conditions
than those suggested in eq 3 in order to dissociate the pyridine
ligand. The reaction gave 2i as a sole product in 72% yield (eq
4). The NEt2 analogue 2k was synthesized in the same manner
in 38% yield.
Scheme 3
Insertion of the nitrile nitrogen-carbon triple bond into the
metal-silicon bonds has been reported by Bergman and
Brookhart,15 Tilley,13b Nakazawa,16 and our group.17 The
cationic complex [Cp*(Me3P)(CH2Cl2)Rh(SiPh3)]+ activates the
carbon-carbon bonds of aryl and alkyl cyanides RCN to give
[Cp*(Me3P)Rh(R)(CNSiPh3)]+, the η2-iminoacyl intermediate
[Cp*(Me3P)Rh(η2(N,C)-RCdN(SiPh3))]+ of which has been
isolated and characterized by X-ray diffraction study. Tilley et
al. also observed similar activation of nitriles by a cationic
iridium(III) silyl complex. Nakazawa et al. reported the insertion
of acetonitrile into an iron-silicon bond. Photoreaction of Cp-
(OC)2FeSiMe3 in acetonitrile solution containing P[MeN(CH2)2-
NMe](OMe) resulted in cleavage of the acetonitrile carbon-
carbon bond to give Cp(OC)LFeMe, CpL2FeMe, and CpL2Fe-
(CN) (L ) P[MeN(CH2)2NMe](OMe)). The same reaction was
also attempted for the germyl analogue Cp(OC)2FeGeMe3.
However, irradiation under the same conditions gave the
substitution product Cp(OC)LFeGeMe3. The silyl ligand on the
iron is thus indispensable for the insertion of acetonitrile
followed by carbon-carbon bond cleavage, in good agreement
with the present results.
In complex 2i, two methyl groups on silicon are diastereotopic
and the NMR signals were observed inequivalently at δ (1H)
1
0.47 and 0.61 and δ (13C) 6.6 and 8.4. The H and 13C NMR
signals for the coordinated pyridine are reasonably assigned as
described in the Experimental Section. The 29Si{1H} NMR
spectrum exhibits a signal at δ 37.8, which is typical of
silylruthenium complexes. The infrared (IR) spectrum displays
a strong band at 1890 cm-1 assignable to the CO stretching
band. In the 1H NMR spectrum of 4i, the resonance of the Ru-H
fragment appeared in the normal region as a very broad signal.
At 253 K, this signal became a sharp singlet (δ -10.53). The
observed fluxional behavior may be attributable to a combined
Berry-Turnstile isomerization as proposed by Smith and
Coville18 or to a reversible E-H reductive elimination/oxidative
addition process (E ) C or Si). No direct evidence is available
on which to distinguish between these two putative processes.
(15) (a) Taw, F. L.; White, P. S.; Bergman, R. G.; Brookhart, M. J. Am.
Chem. Soc. 2002, 124, 4192-4193. (b) Taw, F. L.; Mueller, A. H.; Bergman,
R. G.; Brookhart, M. J. Am. Chem. Soc. 2003, 125, 9808-9813.
(16) Nakazawa, H.; Kawasaki, T.; Miyoshi, K.; Suresh, C. H.; Koga, N.
Organometallics 2004, 23, 117-126.
(17) Hashimoto, H.; Matsuda, A.; Tobita, H. Organometallics 2006, 25,
472-476.
(18) Smith, J. M.; Coville, N. J. Organometallics 1996, 15, 3388-3392.

Insertion of Pyridine into an Iron-Silicon Bond
Organometallics, Vol. 25, No. 26, 2006 6119
Figure 3. ORTEP drawing of 4j with thermal ellipsoids at the
50% probability level. Selected bond distances (Å) and angles
(deg): Ru-Si 2.4353(17), Ru-C15 2.144(6), Ru-C17 1.854(6),
Si-N 1.781(5), C15-Ru-Si 72.18(15), C17-Ru-Si 100.8(2),
C17-Ru-C15 83.7(2).
Figure 4. ORTEP drawing of 5a with thermal ellipsoids at the
50% probability level. Selected bond distances (Å) and angles
(deg): Fe-C15 2.044(2), Fe-C16 2.014(2), Fe-C17 2.024(2), Fe-
C18 2.003(2), Fe-C19 2.037(2), C15-C16 1.416(3), C16-C17
1.399(4), C17-C18 1.404(4), C18-C19 1.408(3), N2-C15 1.442-
(2), N2-C19 1.442(2), Si-N1 1.751(1), Si-N2 1.736(1), C15-
C16-C17 116.7(2), C16-C17-C18 118.0(2), C17-C18-C19
116.9(2), N2-C15-C16 118.1(2), N2-C19-C18 118.2(2), C15-
N2-C19 99.4(1), Si-N2-C15 124.2(1), Si-N2-C19 121.6(1).
The 29Si{1H} NMR spectrum at 298 K exhibits a singlet at δ
52.2. In the IR spectrum, the formation of an Ru(IV) center
through orthometalation is reflected in the large shift of νCO to
a higher energy region (2i, 1890 cm-1; 4i, 1973 cm-1) due to
a decrease in π-back-donation from the Ru dπ orbital to the
CO π* orbital.
As the crystals of 4i were not suitable for X-ray diffraction
study, the p-tolyl analogue, Cp*(OC)HRu{κ2(Si,C)-SiMe2N(o-
C6H3(4-Me))(p-Tol)} (4j), was synthesized in a similar manner.
The molecular structure of 4j is illustrated in Figure 3. The
ruthenium(IV) center of 4j includes Cp* and CO ligands and a
five-membered ring consisting of Ru, Si, N, C10, and C15 atoms
formed through C-H activation at the o-position of the p-Tol
group. The bite angle of C15-Ru-Si is 72.18(15)°, and the
Ru-Si and Ru-C15 bond distances are 2.4353(17) and 2.144-
(6) Å, respectively, within the range expected for each single
bond. The hydrogen atom connected to the ruthenium center
could not be located crystallographically but most probably
exists inside the widened Si-Ru-C17 angle (100.8(2)°), as
signals after heating at 80 °C for 4 h. However, signals
characteristic of the pyridine-insertion product were not detected
at any time, indicating that the insertion of pyridine into the
metal-silicon bonds is peculiar to the iron-silicon system. This
is likely due to the lower bond dissociation energy for the iron-
silicon bond.
1
supported by the H NMR spectroscopic data. A similar five-
membered silaosmacycle has been reported by Tilley et al.,19
who reacted the osmium alkyl complex Cp*(Me3P)2OsCH2-
SiMe3 with HSiMe2S(p-Tol) in cyclohexane at 115 °C to give
Cp*(Me3P)(H)Os{κ2(Si,C)-SiMe2S(o-C6H3(4-Me))} and Cp*-
(Me3P)2OsS(p-Tol) in an 8:1 molar ratio. The same authors also
described the thermal reaction of the ruthenium analogue, Cp*-
(Me3P)2RuCH2SiMe3, with HSiMe2S(p-Tol) in toluene at 100
°C to give Cp*(Me3P)2RuSiMe2S(p-Tol) exclusively, without
formation of the orthometalated product.20
UV irradiation of 3a led to the dissociation of a carbonyl
ligand, affording a new entry of sandwich compound Cp*Fe-
(η5-C5H5NSiMe2NPh2) (5a) in 71% yield (eq 6). The elemental
analysis and mass spectral data for 5a are consistent with this
formula. The IR spectrum did not display strong bands in the
terminal CO region, strongly supporting the absence of a car-
bonyl ligand in 5a. The 1H and 13C NMR signals of the inserted
pyridine fragment appeared at δ (1H) 2.67 (1), 3.36 (2), and
5.48 (3) and δ (13C) 45.2 (1), 78.5 (2), and 85.0 (3), respectively
(numbers in parentheses denote the positions, see eq 6). The
29Si NMR signal was observed at δ -14.2, which is typical of
the tetravalent silicon atom bonded to the nitrogen atom.
When crystals of 2i were dissolved in benzene-d6, 2i was
gradually converted to 4i accompanied by the release of
pyridine. Equilibrium was reached at a 1:1 molar ratio ([2i] )
[4i] ) 13 mM) within several hours at 25 °C (eq 5). Heating of
the equilibrium mixture at 100 °C for 48 h did not promote
insertion, but the equilibrium was shifted to the right side to
yield a mixture of 2i and 4i in a 2:9 molar ratio. Monitoring
1
the thermal reaction of 2k by H NMR spectroscopy revealed
no changes at 60 °C but the emergence of a series of weak
(19) Wanandi, P. W.; Tilley, T. D. Organometallics 1997, 16, 4299-
4313.
(20) Grumbine, S. K.; Straus, D. A.; Tilley, T. D.; Rheingold, A. L.
Polyhedron 1995, 14, 127-148.
The molecular structure of 5a is shown in Figure 4. The five
carbon atoms of the η5-azacyclohexadienyl ligand (C15-C19)

6120 Organometallics, Vol. 25, No. 26, 2006
Iwata et al.
Cp*(OC)2FeH,26 Cp*(OC)2RuMe,23 HSiMe2NR2 (R ) Ph, p-Tol,
and Et),27 ClSiMe2OMe,28 and ClGeMe2NR2 (R ) Ph and Me)29
were prepared according to the literature methods. Other chemicals
were purchased and used as received. NMR data were recorded on
a Bruker ARX-300 or AV-300 spectrometer. 29Si{1H} NMR spectra
were obtained by DEPT pulse sequence. IR spectra were recorded
on a Horiba FT-730 spectrometer, mass spectra were measured
using a JEOL JMS-HX110 or Hitachi M2500S spectrometer, and
UV-visible spectra were recorded on a Shimadzu Multi Spec-1500
spectrometer. Irradiation was performed using an Ushio UM-452
450 W medium-pressure Hg lamp via a Pyrex glass filter at 5 °C.
are nearly coplanar with a mean deviation of 0.0130 Å from
planarity. The dihedral angle between two least-square planes
defined by C15-C16-C17-C18-C19 (plane 1) and by C20-
C21-C22-C23-C24 (plane 2) is 3.8°. The nitrogen atom is
located at a distance of 0.724 Å from plane 1. The bond
distances of C15-C16 (1.416(3) Å), C16-C17 (1.399(4) Å),
C17-C18 (1.404(4) Å), and C18-C19 (1.408(3) Å) are the
intermediates between carbon-carbon single and double bonds,
whereas the bond distances of N2-C15 (1.442(2) Å) and N2-
C19 (1.442(2) Å) are in the normal range for nitrogen-carbon
single bonds, indicating delocalization throughout the five
carbon atoms inside the six-membered ring. Thus, 5a can be
best described as a sandwich compound, in which the iron(II)
center is intercalated between the Cp* and η5-C5H5NSiMe2-
NPh2 π-conjugated ligands. The half-sandwich manganese
complex with the η5-azacyclohexadienyl ligand has previously
been reported by Homrighausen,21 who synthesized the man-
ganese complex by coupling of an isocyanide ligand with two
alkyne molecules on the manganese.
Synthesis of Cp*(OC)(C5H5N)FeSiMe2NPh2 (2a). Procedure
A. A Pyrex tube (15 mm o.d.) equipped with a greaseless vacuum
valve was charged with Cp*(OC)2FeSiMe2NPh2 (1a) (153 mg,
0.323 mmol) and connected to a vacuum line. Pyridine (2 mL,
excess) and toluene (15 mL) were introduced into the tube under
high vacuum by the trap-to-trap transfer technique. After sealing
the tube off from the vacuum line, the contents were irradiated for
90 min. Degassing of the tube contents was performed using a
vacuum line by the conventional freeze-pump-thaw technique
every 30 min. The yellow solution gradually turned dark red as
the reaction proceeded. After irradiation, volatiles were removed
under reduced pressure, and the tube was flame-sealed. The tube
was opened under N2 in a glovebox, the residue extracted with
toluene (3 mL × 3), and the dark red extract filtered through a
Celite pad and concentrated in vacuo. Recrystallization of the
residue from toluene/hexane (1:1) at -30 °C gave dark red crystals
Conclusion
The structure of 3a formed through the insertion of a
heterocyclic aromatic compound (pyridine) into the metal-
silicon bond was characterized by X-ray diffraction study for
the first time. In complex 3a, the silicon atom is bound to the
pyridine nitrogen atom, while the iron atom is bound to carbon
atoms, corresponding to the catalytic intermediate proposed by
Harrod et al.3 Among the Cp*(OC)(C5H5N)MER3 systems
examined (i.e., M ) Fe, E ) Si, Ge and M ) Ru, E ) Si), the
insertion of pyridine proceeded exclusively in the case of
aminosilyliron complexes under the moderate conditions. The
amino group is considered to stabilize the transition state and/
or the intermediate, allowing the insertion reaction to proceed
upon coordination to the coordinatively unsaturated iron center.
This finding provides valuable insight into the catalytic mech-
anism for hydrosilylation of heterocyclic aromatic compounds.
It should be noted that the introduction of an amino group onto
silicon also has potential advantages with respect to further
functionalization of the product, as the amino group can be
readily replaced with nucleophiles.
1
of 2a. Yield: 122 mg (0.233 mmol, 72%); H NMR (300 MHz,
benzene-d6): δ 0.59, 0.60 (s, 3H × 2, SiMe2), 1.39 (s, 15H, C5-
3
3
Me5), 5.96 (t, JHH ) 7.2 Hz, 2H, â-NC5H5), 6.44 (t, JHH ) 7.2
3
Hz, 1H, γ-NC5H5), 6.88 (t, JHH ) 7.2 Hz, 2H, p-NPh2), 7.15 (t,
3JHH ) 7.2 Hz, 4H, m-NPh2), 7.22 (d, 3JHH ) 7.2 Hz, 4H, o-NPh2),
8.34 (d, 3JHH ) 7.2 Hz, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz,
benzene-d6) δ 7.1, 8.3 (SiMe2), 9.6 (C5Me5), 90.7 (C5Me5), 121.5
(â-NC5H5), 122.8 (p-NPh2), 127.7 (o-NPh2), 128.6 (m-NPh2), 133.4
(γ-NC5H5), 153.1 (ipso-NPh2), 157.1 (R-NC5H5), 225.4 (CO);
29Si{1H} NMR (59.6 MHz, benzene-d6) δ 53.5; IR (benzene-d6,
cm-1) 1878 (vs, νCO); EI-MS (70 eV) m/z 524 (11, M+), 496 (15,
M+ - CO), 305 (84, M+ - Cp* - Fe - CO), 270 (13, M+ - CO
- SiMe2NPh2), 226 (100, [SiMe2NPh2]+). Anal. Calcd for C30H36-
FeN2OSi: C, 68.69; H, 6.92; N, 5.34. Found: C, 68.87; H, 7.12;
N, 5.08.
Procedure B. Neat HSiMe2NPh2 (690 mg, 3.03 mmol) was
added by syringe to a toluene solution of Cp*(OC)(C5H5N)FeMe
(952 mg, 3.04 mmol) with stirring at room temperature. Immediate
evolution of methane was confirmed. After stirring for 1 h, the
insoluble materials were filtered off using a Celite pad and the
filtrate was concentrated in vacuo to ca. 10 mL. The toluene solution
was layered carefully with 10 mL of hexane. 2a crystallized at -30
°C as dark red crystals. Yield: 1.15 g (2.19 mmol, 72%).
Photolysis of 3a with an η3-C5H5NSiMe2NPh2 ligand resulted
in rearrangement to give 5a with an η5-C5H5NSiMe2NPh2
through dissociation of one carbonyl ligand. Complex 5a
represents a new type of metallocene having two π-conjugated
ligands, Cp* and η5-C5H5NSiMe2NPh2.
Experimental Section
Synthesis of Cp*(OC)(C5H5N)FeSiMe2NMe2 (2b). Complex
2b (100 mg, 0.250 mmol) was synthesized as dark purple crystals
in 61% yield by a method similar to that for 2a (procedure A),
General Procedures. All manipulations were carried out under
a dry nitrogen atmosphere. Reagent-grade toluene, hexane, pentane,
and diethyl ether were distilled from sodium-benzophenone ketyl
immediately prior to use. Benzene-d6 was dried over a potassium
mirror and transferred into an NMR tube under vacuum. Pyridine
was distilled from KOH prior to use. Cp*(OC)2FeSiMe2NR2 (R )
Ph (1a) and Me (1b)),9 Cp*(OC)(C5H5N)FeMe,22 Cp*(OC)2-
FeSiMe2Cl (1c),23 Cp*(OC)2FeSiMe3 (1d),24 [Cp*(OC)2Fe]2,25
1
using 1b (144 mg, 0.412 mmol) and excess pyridine (2 mL). H
NMR (300 MHz, benzene-d6) δ 0.43, 0.69 (s, 3H × 2, SiMe2),
1.53 (s, 15H, C5Me5), 2.69 (s, 6H, NMe2), 5.96 (d,3JHH ) 7.4 Hz,
3
2H, â-NC5H5), 6.47 (t, JHH ) 7.4 Hz, 1H, γ-NC5H5), 8.46 (m,
2H, R-NC5H5); 13C{1H} NMR (75.5 MHz, benzene-d6) δ 3.88, 3.93
(21) Homrighausen, C. L.; Alexander, J. J.; Bauer, J. A. K. Inorg. Chim.
Acta 2002, 334, 419-436.
(26) Bullock, R. M.; Samsel, E. G. J. Am. Chem. Soc. 1990, 112, 6886-
6898.
(27) (a) Tamao, K.; Nakajo, E.; Ito, Y. Tetrahedron 1988, 44, 3997-
4007. (b) Tamao, K.; Kawachi, A.; Nakagawa, Y.; Ito, Y. J. Organomet.
Chem. 1994, 473, 29-34. (c) Kawachi, A.; Tamao, K. J. Am. Chem. Soc.
2000, 122, 1919-1926.
(28) Hopper, S. P.; Tremelling, M. J.; Goldman, E. W. J. Organomet.
Chem. 1978, 156, 331-340.
(29) Yoder, C. H.; Zuckerman, J. J. J. Am. Chem. Soc. 1966, 88, 4831-
4839.
(22) Hashimoto, H.; Matsuda, A.; Tobita, H. Chem. Lett. 2005, 34, 1374-
1375.
(23) Okazaki, M.; Satoh, K.; Akagi, T.; Iwata, M.; Jung, K. A.; Shiozawa,
R.; Okada, H.; Ueno, K.; Tobita, H.; Ogino, H. J. Organomet. Chem. 2002,
645, 201-205.
(24) Randolph, C. L.; Wrighton, M. S. Organometallics 1987, 6, 365-
371.
(25) Catheline, D.; Astruc, D. Organometallics 1984, 3, 1094-1100.

Insertion of Pyridine into an Iron-Silicon Bond
Organometallics, Vol. 25, No. 26, 2006 6121
(SiMe2), 9.8 (C5Me5), 40.7 (NMe2), 90.5 (C5Me5), 122.9 (â-NC5H5),
133.0 (γ-NC5H5), 156.7 (R-NC5H5), 224.1 (CO); 29Si{1H} NMR
(59.6 MHz, benzene-d6) δ 56.9; IR (benzene-d6, cm-1) 1869 (vs,
by a method similar to that for 2a (procedure A), using 1d (166
mg, 0.518 mmol) and pyridine (2 mL, excess). 1H NMR (300 MHz,
benzene-d6) δ 0.48 (s, 9H, SiMe3), 1.52 (s, 15H, C5Me5), 5.98 (t,
CO); EI-MS (70 eV) m/z 400 (12, M+), 372 (14, M+ - CO), 270
3JHH ) 7.4 Hz, 2H, â-NC5H5), 6.47 (t, JHH ) 7.4 Hz, 1H,
3
ν
(25, M+ - CO - SiMe2NMe2), 181 (88), 102 (100, [SiMe2-
NMe2]+). Anal. Calcd for C20H32FeN2OSi: C, 59.99; H, 8.06; N,
7.00. Found: C, 59.72; H, 8.19; N, 6.67.
γ-NC5H5), 8.40 (br, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz,
benzene-d6) δ 4.8 (SiMe3), 9.9 (C5Me5), 90.1 (C5Me5), 123.1 (â-
NC5H5), 133.2 (γ-NC5H5), 156.7 (R-NC5H5), 222.5 (CO); 29Si{1H}
NMR (59.6 MHz, benzene-d6) δ 40.7; IR (benzene-d6, cm-1) 1873
(vs, νCO); EI-MS (70 eV) m/z 371 (3, M+), 264 (18, M+ - CO -
NC5H5), 190 (100, M+ - CO - NC5H5 - SiMe3 - H). Anal. Calcd
for C19H29FeNOSi: C, 61.45; H, 7.87; N, 3.77. Found: C, 61.07;
H, 8.06; N, 3.83.
Synthesis of Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NPh2} (3a).
A Pyrex tube (10 mm o.d.) equipped with a greaseless vacuum
valve was charged with 2a (40 mg, 76 µmol), and toluene (10 mL)
was then introduced into this tube under high vacuum by the trap-
to-trap transfer technique. The tube was flame-sealed, heated at 60
°C for 48 h, and then opened under N2 in a glovebox. Volatiles
were removed under reduced pressure, and the residue was extracted
with pentane (5 mL × 2). The extract was filtered through a Celite
pad. Cooling of the concentrated pentane solution at -30 °C
afforded orange crystals of 3a. Yield: 22 mg (42 µmol, 55%); 1H
NMR (300 MHz, benzene-d6) δ 0.26, 0.34 (s, 3H × 2, SiMe2),
1.50 (s, 15H, C5Me5), 1.77 (t, 3JHH ) 5.4 Hz, 1H, H2), 3.74 (t, 3JHH
Synthesis of Cp*(OC)2FeSiMe2OMe (1e). An orange solution
of Cp*(OC)2FeH (1.23 g, 4.96 mmol) in diethyl ether (50 mL) was
cooled to -45 °C and treated with n-BuLi (1.5 M hexane solution,
3.3 mL, 5.0 mmol). After stirring for 10 min at -45 °C, the mixture
became an orange suspension. ClSiMe2OMe (1.07 g, 8.59 mmol)
was added dropwise to the suspension at -45 °C, and the solution
was subsequently allowed to warm to room temperature. After
stirring for 12 h, volatiles were evaporated under reduced pressure,
and the residue was extracted with hexane (10 mL × 3). The extract
was filtered through a Celite pad, and then the filtrate was
concentrated to dryness in vacuo. Purification of the residue by
silica gel flash chromatography using toluene as an eluent gave
two yellow bands. Evaporation of the solvent in vacuo from the
first fraction and recrystallization of the residue from toluene/hexane
(1:1) at -30 °C yielded yellow crystals of Cp*(OC)2FeSiMe2Cl
(1c) (107 mg, 0.314 mmol, 6%). Evaporation of the solvent in vacuo
from the second fraction afforded 1e (752 mg, 2.24 mmol, 45%):
1H NMR (300 MHz, benzene-d6) δ 0.68 (s, 6H, SiMe2), 1.56 (s,
15H, C5Me5), 3.44 (s, 3H, OMe); 13C{1H} NMR (75.5 MHz,
benzene-d6) δ 7.0 (SiMe2), 9.7 (C5Me5), 50.6 (OMe), 95.2 (C5-
Me5), 217.7 (CO); 29Si{1H} NMR (59.6 MHz, benzene-d6) δ 69.0;
IR (benzene-d6, cm-1) 1975, 1919 (vs, νCO); EI-MS (70 eV) m/z
336 (47, M+), 321 (7, M+ - Me), 308 (44, M+ - CO), 280 (100,
M+ - 2CO), 190 (79, M+ - 2CO - SiMe2OMe - H), 89 (19,
[SiMe2OMe]+). Anal. Calcd for C15H24FeO3Si: C, 53.57; H, 7.19.
Found: C, 53.96; H, 7.46.
3
3
) 5.6 Hz, 1H, H3), 5.30 (t, JHH ) 6.3 Hz, 1H, H4), 5.47 (d, JHH
3
3
) 7.1 Hz, 1H, H5), 5.73 (d, JHH ) 5.3 Hz, 1H, H1), 6.89 (t, JHH
) 7.2 Hz, 2H, p-NPh2), 7.06 (d, 3JHH ) 7.2 Hz, 4H, o-NPh2), 7.13
(t, JHH ) 7.2 Hz, 4H, m-NPh2); 13C{1H} NMR (75.5 MHz,
3
benzene-d6) δ -2.2, -1.1 (SiMe2), 9.8 (C5Me5), 90.6 (C5Me5), 45.1
(C2), 51.2 (C3), 76.9 (C1), 110.8 (C4), 121.1 (C5), 123.2 (p-NPh2),
125.4 (o-NPh2), 129.5 (m-NPh2), 148.4 (ipso-NPh2), 225.1 (CO);
29Si{1H} NMR (59.6 MHz, benzene-d6) δ -2.3; IR (benzene-d6,
cm-1) 1911 (vs, νCO); EI-MS (70 eV) m/z 524 (7, M+), 496 (14,
M+ - CO), 402 (15, M+ - CO - Me - NC5H5), 305 (75, [C5H5-
NSiMe2NPh2]+), 270 (17, M+ - CO - SiMe2NPh2), 226 (100,
[SiMe2NPh2]+). Anal. Calcd for C30H36FeN2OSi: C, 68.69; H, 6.92;
N, 5.34. Found: C, 68.75; H, 6.72; N, 5.41.
Monitoring the Thermal Reaction of Cp*(OC)(C5H5N)Fe-
SiMe2NMe2 (2b) by NMR Spectroscopy. A Pyrex NMR tube was
charged with 2b (1.0 mg, 2.5 µmol) and C6Me6 (0.5 mg, internal
standard). Benzene-d6 (0.7 mL) was then introduced into this tube
under high vacuum by the trap-to-trap-transfer technique. The NMR
tube was flame-sealed and then heated to 60 °C. The reaction was
monitored by the 1H NMR spectroscopy. The dark purple solution
of 2b gradually turned orange. After heating at 60 °C for 48 h, 3b
was obtained in 86% NMR yield: 1H NMR (300 MHz, benzene-
d6) δ 0.17, 0.26 (s, 3H × 2, SiMe2), 1.57 (s, 15H, C5Me5), 1.73 (t,
Synthesis of Cp*(OC)(C5H5N)FeSiMe2OMe (2e). Compound
2e (136 mg, 0.351 mmol) was synthesized as purple crystals in
50% yield by a method similar to that for 2a (procedure A), using
1
1e (237 mg, 0.705 mmol) and pyridine (2 mL, excess). H NMR
3
3JHH ) 5.9 Hz, 1H, H2), 2.45 (s, 6H, NMe2), 3.76 (t, JHH ) 5.5
(300 MHz, benzene-d6) δ 0.24, 0.72 (s, 3H × 2, SiMe2), 1.52 (s,
3
Hz, 1H, H3), 5.23-5.30 (m, 2H, H4, H5), 5.53 (d, JHH ) 5.0 Hz,
3
15H, C5Me5), 3.63 (s, 3H, OMe), 6.07 (t, JHH ) 6.9 Hz, 2H,
1H, H1); 13C{1H} NMR (75.5 MHz, benzene-d6) δ -3.4, -3.3
(SiMe2), 9.9 (C5Me5), 37.7 (NMe2), 89.5 (C5Me5), 44.1 (C2), 51.3
(C3), 78.8 (C1), 109.6 (C4), 122.1 (C5), 223.1 (CO); 29Si{1H} NMR
(59.6 MHz, benzene-d6) δ 0.3; IR (benzene-d6, cm-1) 1907 (vs,
â-NC5H5), 6.53 (t, 3JHH ) 6.9 Hz, 1H, γ-NC5H5), 8.59 (d, 3JHH
)
6.9 Hz, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz, benzene-d6) δ
3.4, 4.2 (SiMe2), 9.8 (C5Me5), 50.9 (OMe), 90.6 (C5Me5), 123.2
(â-NC5H5), 133.7 (γ-NC5H5), 156.6 (br, R-NC5H5), 222.0 (CO);
29Si{1H} NMR (59.6 MHz, benzene-d6) δ 77.4; IR (benzene-d6,
cm-1) 1873 (vs, νCO); EI-MS (70 eV) m/z 387 (27, M+), 308 (50,
ν
CO); EI-MS (70 eV) m/z 400 (13, M+), 372 (15, M+ - CO), 270
(17, M+ - CO - SiMe2NMe2), 181 (91), 102 (100, [SiMe2-
NMe2]+).
M+ - NC5H5), 280 (100, M+ - CO - NC5H5), 190 (39, M+
CO - NC5H5 - SiMe2OMe - H). Anal. Calcd for C19H29FeNO2-
Si: C, 58.91; H, 7.55; N, 3.62. Found: C, 58.41; H, 7.70; N, 3.53.
-
Synthesis of Cp*(OC)(C5H5N)FeSiMe2Cl (2c). Compound 2c
(204 mg, 0.521 mmol) was synthesized as orange crystals in 60%
yield by a method similar to that for 2a (procedure A), using 1c
(295 mg, 0.866 mmol) and pyridine (5 mL, excess). 1H NMR (300
MHz, benzene-d6) δ 0.44, 1.07 (s, 3H × 2, SiMe2), 1.49 (s, 15H,
Monitoring the Thermal Reaction of Cp*(OC)(C5H5N)-
FeSiMe2R (R ) Cl (2c), Me, (2d), OMe (2e)). For 2c: Heating
at 60 °C did not result in changes in the 1H NMR spectrum. After
heating for 24 h at 90 °C, 2c was recovered in 79% NMR yield
with the formation of [Cp*(OC)2Fe]2 (6%) and Cp*2Fe (3%).
Prolonged heating led to decomposition, and the NMR signals
characteristic of the pyridine-insertion product were not detected.
For 2d: Heating at 60 °C did not result in changes in the 1H NMR
spectrum. After heating for 24 h at 90 °C, unidentified broad signals
3
C5Me5), 6.07 (br, 2H, â-NC5H5), 6.50 (t, JHH ) 7.5 Hz, 1H,
γ-NC5H5), 8.55 (br, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz,
benzene-d6) δ 9.5 (C5Me5), 9.9, 10.3 (SiMe2), 91.4 (C5Me5), 123.7
(â-NC5H5), 134.6 (γ-NC5H5), 157.4 (br, R-NC5H5), 220.3 (CO);
29Si{1H} NMR (59.6 MHz, benzene-d6) δ 99.0; IR (benzene-d6,
cm-1) 1882 (vs, νCO); EI-MS (70 eV) m/z 391 (7, M+), 284 (33,
M+ - CO - NC5H5), 190 (100, M+ - CO - NC5H5 - SiMe2Cl
- H). Anal. Calcd for C18H26ClFeNOSi: C, 55.18; H, 6.69; N,
3.58. Found: C, 55.42; H, 6.82; N, 3.47.
1
were observed in the H NMR spectrum, where 2d remained in
40% NMR yield and the NMR signals characteristic of the pyridine-
insertion product were not detected. For 2e: Heating at 60 °C did
1
Synthesis of Cp*(OC)(C5H5N)FeSiMe3 (2d). Compound 2d (88
mg, 0.24 mmol) was synthesized as purple crystals in 46% yield
not result in changes in the H NMR spectrum. After heating for
24 h at 90 °C, the formation of Cp*(OC)Fe{η3(C,C,C)-C5H5-

6122 Organometallics, Vol. 25, No. 26, 2006
Iwata et al.
NSiMe2OMe} (3e) was confirmed in 18% NMR yield together with
Me2Si(OMe)2 (24%) and the recovered 2e (9%). Weak unidentified
signals were also observed. Prolonged heating for 36 h at 90 °C
resulted in the complete disappearance of 2e to afford 3e and Me2-
Si(OMe)2 in yields of 16% and 28%, respectively. 3e: 1H NMR
(300 MHz, benzene-d6) δ 0.12, 0.31 (s, 3H × 2, SiMe2), 1.53 (s,
15H, C5Me5), 3.39 (s, 3H, OMe), 1.79 (br, 1H, H2), 3.70 (br, 1H,
H3), 5.21 (br, 1H, H4), 5.32 (br, 1H, H5), 5.62 (br, 1H, H1); 13C-
{1H} NMR (75.5 MHz, benzene-d6) δ -3.4, -1.4 (SiMe2), 10.0
(C5Me5), 50.2 (OMe), 45.5 (C2), 51.0 (C3), 77.9 (C1), 110.3 (C4),
121.5 (C5); 29Si{1H} NMR (75.5 MHz, benzene-d6) δ 2.2.
in 63% yield by a method similar to that for 2a (procedure A),
using 1g (200 mg, 0.508 mmol) and pyridine (5 mL, excess). H
1
NMR (300 MHz, benzene-d6) δ 0.50, 0.75 (s, 3H × 2, GeMe2),
1.50 (s, 15H, C5Me5), 2.77 (s, 6H, NMe2), 6.00 (t, 3JHH ) 6.6 Hz,
2H, â-NC5H5), 6.49 (t, 3JHH ) 6.6 Hz, 1H, γ-NC5H5), 8.44 (d, 3JHH
) 6.6 Hz, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz, benzene-d6)
δ 1.6, 3.1 (GeMe2), 9.9 (C5Me5), 43.3 (NMe2), 89.8 (C5Me5), 123.3
(â-NC5H5), 134.0 (γ-NC5H5), 157.4 (R-NC5H5), 224.2 (CO); IR
(benzene-d6, cm-1) 1877 (vs, νCO). Anal. Calcd for C20H32-
FeGeN2O: C, 53.99; H, 7.25; N, 6.30. Found: C, 53.55; H, 7.17;
N, 5.76.
Synthesis of Cp*(OC)2FeGeMe2NPh2 (1f). To a solution of
ClGeMe2NPh2 (550 mg, 1.80 mmol) in tetrahydrofuran (THF; 20
mL) was added a solution of K[Cp*(OC)2Fe] in THF (20 mL),
which was prepared by reduction of [Cp*(OC)2Fe]2 (510 mg, 1.03
mmol) with Na/K alloy (Na, 95 mg, 4.1 mmol; K, 483 mg, 12.4
mmol). The reaction mixture was stirred at -45 °C for 30 min,
allowed to warm to room temperature, and stirred for a further 2
h. Volatiles were removed under reduced pressure, and the residue
was extracted with hexane (10 mL × 3). The extract was filtered
through a Celite pad and concentrated under reduced pressure.
Recrystallization of the residue from hexane at -75 °C afforded
yellow crystals of 1f. Yield: 542 mg (1.05 mmol, 58%); 1H NMR
(300 MHz, benzene-d6) δ 0.74 (s, 6H, GeMe2), 1.39 (s, 15H, C5-
Synthesis of Cp*(OC)(C5H5N)FeGeMe3 (2h). Compound 2h
(242 mg, 0.582 mmol) was synthesized as dark purple crystals in
71% yield by a method similar to that for 2a (procedure A), using
1h (300 mg, 0.822 mmol) and pyridine (2 mL, excess). H NMR
(300 MHz, benzene-d6) δ 0.53 (s, 9H, GeMe3), 1.50 (s, 15H, C5-
1
3
3
Me5), 6.00 (t, JHH ) 6.9 Hz, 2H, â-NC5H5), 6.49 (t, JHH ) 6.9
Hz, 1H, γ-NC5H5), 8.44 (d, JHH ) 6.9 Hz, 2H, R-NC5H5); 13C-
3
{1H} NMR (75.5 MHz, benzene-d6) δ 3.3 (GeMe3), 9.9 (C5Me5),
89.2 (C5Me5), 123.1 (â-NC5H5), 133.6 (γ-NC5H5), 156.6 (R-
NC5H5), 223.0 (CO); IR (benzene-d6, cm-1) 1876 (vs, νCO). Anal.
Calcd for C19H29FeGeNO: C, 54.87; H, 7.03; N, 3.37. Found: C,
54.99; H, 7.07; N, 3.21.
Monitoring the Thermal Reaction of Cp*(OC)(C5H5N)-
FeGeMe2R (R ) NPh2 (2f), NMe2 (2g), Me (2h)). For 2f: Heating
at 60 °C did not result in changes in the 1H NMR spectrum. After
heating for 24 h at 110 °C, 2f remained in 70% NMR yield, and
several weak unidentified signals emerged in the 1H NMR spectrum.
However, the pyridine-insertion products were not detected at all.
For 2g: Heating at 60 °C did not produce changes in the 1H NMR
spectrum. Heating at 80 °C caused the signals of 2g to weaken
gradually, and prolonged heating for 8 h at 80 °C resulted in the
disappearance of 2g to afford unidentified products with the release
of free pyridine. The pyridine-insertion product was not observed
in the 1H NMR spectrum. For 2h: Heating at 60 °C did not result
in changes in the 1H NMR spectrum. After heating for 24 h at 110
°C, 2h was recovered in 75% NMR yield accompanied by the
formation of [Cp*(OC)2Fe]2 (5% NMR yield). The NMR signals
characteristic of the pyridine-insertion product were not detected.
3
Me5), 6.90 (t, JHH ) 7.2 Hz, 2H, p-Ph), 7.15-7.26 (m, 8H, o,m-
Ph); 13C{1H} NMR (75.5 MHz, benzene-d6) δ 9.6 (GeMe2), 9.8
(C5Me5), 95.3 (C5Me5), 121.0 (p-Ph), 125.6 (o-Ph), 129.2 (m-Ph),
152.7 (ipso-Ph), 217.9 (CO); IR (KBr, cm-1) 1975, 1936 (vs, νCO).
Anal. Calcd for C26H31FeGeNO2: C, 60.29; H, 6.03; N, 2.70.
Found: C, 60.19; H, 6.38; N, 2.53.
Synthesis of Cp*(OC)2FeGeMe2NMe2 (1g). Compound 1g
(1.23 g, 3.12 mmol) was synthesized as light red crystals in 69%
yield by a method similar to that for 1f, using [Cp*(OC)2Fe]2 (1.11
g, 2.25 mmol), Na/K alloy (Na, 156 mg, 6.78 mmol; K, 794 mg,
1
20.3 mmol), and ClGeMe2NMe2 (1.03 g, 5.65 mmol). H NMR
(300 MHz, benzene-d6) δ 0.68 (s, 6H, GeMe2), 1.54 (s, 15H, C5-
Me5), 2.70 (s, 6H, NMe2); 13C{1H} NMR (75.5 MHz, benzene-d6)
δ 4.8 (GeMe2), 9.9 (C5Me5), 42.4 (NMe2), 94.9 (C5Me5), 218.2
(CO); IR (benzene-d6, cm-1) 1973, 1917 (vs, νCO). Anal. Calcd
for C16H27FeGeNO2: C, 48.79; H, 6.91; N, 3.56. Found: C, 48.41;
H, 6.91; N, 2.91.
Kinetic Study of Thermal Conversion from Cp*(OC)(C5H5N)-
FeSiMe2NPh2 (2a) to Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe2NPh2}
(3a). A 10 mL volumetric flask was charged with 2a (103 mg,
0.196 mmol) and C6Me6 (9.0 mg, internal standard). Benzene-d6
was added to the flask to make the volume of the solution up to
10.0 mL. Five NMR tubes were filled with this solution (1.96 ×
10-3 M) and flame-sealed under high vacuum. The samples were
heated at five different temperatures (328, 333, 338, 343, and 348
K) in an oil bath. Thermal conversion from 2a to 3a was
Synthesis of Cp*(OC)2FeGeMe3 (1h). Compound 1h (739 mg,
2.03 mmol) was synthesized as orange needles in 51% yield by a
method similar to that for 1f, using [Cp*(OC)2Fe]2 (986 mg, 2.00
mmol), Na/K alloy (Na, 108 mg, 4.70 mmol; K, 586 mg, 15.0
1
mmol), and BrGeMe3 (1.54 g, 7.79 mmol). H NMR (300 MHz,
benzene-d6) δ 0.66 (s, 9H, GeMe3), 1.50 (s, 15H, C5Me5); 13C-
{1H} NMR (75.5 MHz, benzene-d6) δ 5.6 (GeMe3), 9.9 (C5Me5),
94.2 (C5Me5), 218.1 (CO); IR (KBr pellet, cm-1) 1968, 1905 (vs,
1
periodically monitored by H NMR spectroscopy. A linear cor-
νCO). Anal. Calcd for C15H24FeGeO2: C, 49.39; H, 6.63. Found:
relation was found between ln(At/A0) and time, where A0 and At
are the molar fractions of 2a at time 0 and t (see Supporting
Information).
C, 49.48; H, 6.58.
Synthesis of Cp*(OC)(C5H5N)FeGeMe2NPh2 (2f). Compound
2f (197 mg, 0.346 mmol) was synthesized as purple crystals in
60% yield by a method similar to that for 2a (procedure A), using
Synthesis of Cp*(OC)(C5H5N)RuMe. A Pyrex tube (20 mm
o.d.) equipped with a greaseless vacuum valve was charged with
Cp*(OC)2RuMe (398 mg, 1.29 mmol) and connected to a vacuum
line. Pyridine (1 mL, excess) and hexane (15 mL) were introduced
into this tube under high vacuum by the trap-to-trap transfer
technique. After sealing the tube off from the vacuum line, the
solution was irradiated for 3 h. Degassing of the solution was
performed using a vacuum line by the conventional freeze-pump-
thaw technique every 30 min. The light red solution gradually turned
dark orange as the reaction proceeded. After irradiation, volatiles
were removed under reduced pressure, and the tube was reopened
under N2 in a glovebox. The residue was extracted with hexane (5
mL × 3), the dark orange extract was filtered through a Celite pad,
and the filtrate was concentrated in vacuo. Recrystallization of the
residue from hexane at -30 °C gave dark orange crystals of Cp*-
1
1f (300 mg, 0.579 mmol) and pyridine (5 mL, excess). H NMR
(300 MHz, benzene-d6) δ 0.68 (s, 6H, GeMe2), 1.37 (s, 15H, C5-
3
3
Me5), 6.00 (t, JHH ) 6.9 Hz, 2H, â-NC5H5), 6.46 (t, JHH ) 6.9
Hz, 1H, γ-NC5H5), 6.82 (t, 3JHH ) 7.2 Hz, 2H, p-Ph), 7.00 (t, 3JHH
3
) 7.2 Hz, 4H, m-Ph), 7.15 (d, JHH ) 7.2 Hz, 4H, o-Ph), 8.34 (d,
3JHH ) 6.9 Hz, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz, benzene-
d6) δ 7.7, 8.1 (GeMe2), 9.8 (C5Me5), 90.0 (C5Me5), 119.6 (â-
NC5H5), 123.0 (p-Ph), 125.3 (o-Ph), 128.7 (m-Ph), 134.3 (γ-NC5H5),
153.8 (ipso-Ph), 157.5 (R-NC5H5), 224.4 (CO); IR (benzene-d6,
cm-1) 1888 (vs, νCO). Anal. Calcd for C30H36FeGeN2O: C, 63.32;
H, 6.38; N, 4.92. Found: C, 62.95; H, 6.61; N, 4.80.
Synthesis of Cp*(OC)(C5H5N)FeGeMe2NMe2 (2g). Compound
2g (143 mg, 0.321 mmol) was synthesized as dark purple crystals

Insertion of Pyridine into an Iron-Silicon Bond
Organometallics, Vol. 25, No. 26, 2006 6123
(OC)(C5H5N)RuMe. Yield: 343 mg (0.957 mmol, 74%); 1H NMR
(300 MHz, benzene-d6) δ 0.59 (s, 3H, RuMe), 1.60 (s, 15H, C5-
132.4, 136.2, 143.8, 144.2, 156.5 (aromatic), 205.7 (CO); 29Si{1H}
NMR (benzene-d6, 59.6 MHz, 298 K) δ 50.9; IR (benzene-d6, cm-1
)
3
3
Me5), 6.15 (t, JHH ) 6.9 Hz, 2H, â-NC5H5), 6.58 (t, JHH ) 6.9
1971 (νCO). Anal. Calcd. for C27H35NORuSi: C, 62.52; H, 6.80;
N, 2.70. Found: C, 62.79; H, 6.75; N, 2.90.
Hz, 1H, γ-NC5H5), 8.26 (d, JHH ) 6.9 Hz, 2H, R-NC5H5); 13C-
3
{1H} NMR (75.5 MHz, benzene-d6) δ -7.0 (RuMe), 9.7 (C5Me5),
92.2 (C5Me5), 123.9 (â-NC5H5), 134.3 (γ-NC5H5), 155.9 (R-
NC5H5), 210.3 (CO); IR (benzene-d6, cm-1) 1884 (νCO). Anal. Calcd
for C17H23NORu: C, 56.96; H, 6.47; N, 3.91. Found: C, 56.93;
H, 6.38; N, 3.85.
Thermal Reaction of Cp*(OC)(C5H5N)RuMe with
HSiMe2NPh2 in the Presence of Excess Pyridine. A Pyrex tube
(15 mm o.d.) equipped with a greaseless vacuum valve was charged
with Cp*(OC)(C5H5N)RuMe (125 mg, 0.349 mmol) and HSiMe2-
NPh2 (80 mg, 0.35 mmol). Toluene (5 mL) and pyridine (215 mg,
2.72 mmol) were then introduced into this tube under high vacuum
by the trap-to-trap transfer technique. The tube was sealed, heated
at 80 °C for 12 h, and then opened under N2 in a glovebox. Volatiles
were removed under reduced pressure. The NMR spectroscopic data
of the residue revealed selective formation of Cp*(OC)(C5H5N)-
RuSiMe2NPh2 (2i). Recrystallization of the residue from toluene/
hexane (1:1) at -30 °C gave light yellow crystals of 2i. Yield:
143 mg (0.251 mmol, 72%).
Reaction of Cp*(OC)(C5H5N)RuMe with HSiMe2NPh2. A
Pyrex tube (20 mm o.d.) equipped with a greaseless vacuum valve
was charged with Cp*(OC)(C5H5N)RuMe (370 mg, 1.03 mmol)
and HSiMe2NPh2 (230 mg, 1.01 mmol). Toluene (15 mL) was then
introduced into this tube under high vacuum by the trap-to-trap
transfer technique. The solution was stirred at room temperature
for 6 h, after which volatiles were removed in vacuo. The NMR
spectroscopic data indicated a 5:4 mixture of Cp*(OC)(C5H5N)-
RuSiMe2NPh2 (2i) and Cp*(OC)HRu{κ2(Si,C)-SiMe2N(o-C6H4)-
(Ph)} (4i). Recrystallization of the residue from toluene/pentane
(1:1) at -30 °C afforded 2i as orange crystals and 4i as light yellow
crystals, which were separated on the basis of color. Yield of 2i:
170 mg (0.298 mmol, 29%). Yield of 4i: 155 mg (0.316 mmol,
31%). Data for 2i: 1H NMR (300 MHz, benzene-d6) δ 0.47, 0.61
(s, 3H × 2, SiMe2), 1.55 (s, 15H, C5Me5), 6.11 (t, 3JHH ) 6.9 Hz,
Thermal Reaction of Cp*(OC)(C5H5N)RuMe with HSiMe2NEt2
in the Presence of Excess Pyridine. This reaction was carried out
by a method similar to that employed for HSiMe2NPh2, in this case
using Cp*(OC)(C5H5N)RuMe (112 mg, 0.313 mmol), HSiMe2NEt2
(40 mg, 0.30 mmol), and pyridine (147 mg, 1.86 mmol). After
stirring at 80 °C for 12 h, volatiles were removed under reduced
pressure, and the residue was extracted with hexane (3 mL × 3).
The extract was filtered through a Celite pad. Cooling of the
concentrated filtrate at -30 °C afforded a yellow powder of Cp*-
(OC)(C5H5N)RuSiMe2NEt2 (2k). Yield: 55 mg (0.12 mmol, 38%);
1H NMR (300 MHz, benzene-d6) δ 0.27, 0.55 (s, 3H × 2, SiMe2),
3
2H, â-NC5H5), 6.56 (t, JHH ) 6.9 Hz, 1H, γ-NC5H5), 6.86-6.91
3
(m, 2H, p-Ph), 7.12-7.17 (m, 8H, o,m-Ph), 8.29 (d, JHH ) 6.9
Hz, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz, benzene-d6) δ 6.6,
8.4 (SiMe2), 10.0 (C5Me5), 94.8 (C5Me5), 121.1 (â-NC5H5), 123.4
(p-Ph), 126.8 (o-Ph), 128.7 (m-Ph), 133.9 (γ-NC5H5), 152.7 (ipso-
Ph), 156.2 (R-NC5H5), 211.7 (CO); 29Si{1H} NMR (59.6 MHz,
benzene-d6) 37.8; IR (benzene-d6, cm-1) 1890 (vs, νCO). Anal. Calcd
for C30H36N2ORuSi: C, 63.24; H, 6.37; N, 4.92. Found: C, 63.57;
H, 6.40; N, 4.79. Data for 4i: 1H NMR (benzene-d6, 300 MHz,
298 K) δ -10.53 (br, 1H, RuH), 0.53, 0.56 (s, 3H × 2, SiMe2),
3
1.25 (t, JHH ) 6.9 Hz, 6H, N(CH2CH3)2), 1.69 (s, 15H, C5Me5),
3.14, 3.22 (q, 3JHH ) 6.9 Hz, 2H × 2, N(CH2CH3)2), 6.07 (t, 3JHH
3
) 6.9 Hz, 2H, â-NC5H5), 6.54 (t, JHH ) 6.9 Hz, 1H, γ-NC5H5),
8.38 (d, 3JHH ) 6.9 Hz, 2H, R-NC5H5); 13C{1H} NMR (75.5 MHz,
benzene-d6) δ 4.2, 6.8 (SiMe2), 10.3 (C5Me5), 16.4 (N(CH2CH3)2),
41.9 (N(CH2CH3)2), 94.5 (C5Me5), 124.0 (â-NC5H5), 133.7 (γ-
NC5H5), 156.2 (R-NC5H5), 211.4 (CO); 29Si{1H} NMR (59.6 MHz,
benzene-d6) δ 41.5; IR (benzene-d6, cm-1) 1882 (vs, νCO). Anal.
Calcd for C22H36N2ORuSi: C, 55.78; H, 7.66; N, 5.91. Found: C,
55.23; H, 7.34; N, 5.31.
3
1.49 (s, 15H, C5Me5), 6.80 (t, JHH ) 7.5 Hz, aromatic), 7.00 (m,
aromatic), 7.20-7.28 (m, aromatic); 1H NMR (toluene-d8, 253 K)
δ -10.53 (s, 1H, RuH), 0.55, 0.60 (s, 3H × 2, SiMe), 1.44 (s,
3
15H, C5Me5), 6.84 (t, JHH ) 6.9 Hz, 2H, aromatic), 7.14 (s, 3H,
3
3
aromatic), 7.27 (t, JHH ) 7.5 Hz, 3H, aromatic), 7.48 (d, JHH
)
Monitoring the Thermal Reaction of Cp*(OC)(C5H5N)-
RuSiMe2NR2 (R ) Ph (2i), Et (2k)). For 2i: To a Pyrex NMR
tube was added a benzene-d6 solution (0.7 mL) of 2i (10 mg, 18
µmol) and C6Me6 (0.5 mg, internal standard). The NMR tube was
flame-sealed under high vacuum. The reaction at 25 °C was
7.2 Hz, 1H, aromatic); 13C{1H} NMR (benzene-d6, 75.5 MHz, 298
K) δ 4.9, 9.9 (SiMe), 100.7 (C5Me5), 120.5, 123.7, 126.9, 129.7,
146.3, 159.0 (aromatic), 205.4 (CO); (toluene-d8, 253 K) δ 4.7,
9.75 (SiMe), 9.84 (C5Me5), 100.3 (C5Me5), 112.1, 120.3, 123.2,
125.6, 127.2, 129.5, 136.2, 143.1, 146.0, 158.3 (aromatic), 205.3
(CO); 29Si{1H} NMR (benzene-d6, 59.6 MHz, 298 K) δ 52.2; IR
(benzene-d6, cm-1) 1973 (νCO). Anal. Calcd for C25H31NORuSi:
C, 61.19; H, 6.37; N, 2.85. Found: C, 61.47; H, 6.32; N, 2.78.
1
monitored by H NMR spectroscopy. After 5 h, an equilibrium
between 2i and 4i was attained at a 1:1 molar ratio. The equilibrium
mixture was heated at 100 °C while monitoring by 1H NMR
spectroscopy. After 48 h, the equilibrium had shifted to the side of
4i, giving a 2:9 mixture of 2i and 4i. However, the pyridine-insertion
product was not observed in the 1H NMR spectrum. For 2k:
Heating at 60 °C did not result in changes in the 1H NMR spectrum.
After heating for 4 h at 80 °C, several unidentified signals emerged
Reaction of Cp*(OC)(C5H5N)RuMe with HSiMe2N(p-Tol)2.
This reaction was carried out by a method similar to that employed
for HSiMe2NPh2, in this case using Cp*(OC)(C5H5N)RuMe (288
mg, 0.803 mmol) and HSiMe2N(p-Tol)2 (198 mg, 0.775 mmol).
After 6 h at room temperature, the NMR spectroscopic data
indicated a 1:1 mixture of Cp*(OC)(C5H5N)RuSiMe2N(p-Tol)2 (2j)
and Cp*(OC)HRu{κ2(Si,C)-SiMe2N(o-C6H3(4-Me))(p-Tol)} (4j).
Recrystallization of the residue from toluene/pentane (1:1) at -30
°C gave yellow crystals of 4j. Yield: 134 mg (0.258 mmol, 33%);
1H NMR (benzene-d6, 300 MHz, 298 K) δ -10.51 (br, 1H, RuH),
0.58, 0.60 (s, 3H × 2, SiMe2), 1.52 (s, 15H, C5Me5), 2.19, 2.29 (s,
1
in the H NMR spectrum, but 2k remained in 18% NMR yield.
The NMR signals of the pyridine-insertion product were not
observed.
Synthesis of Cp*Fe(η5-C5H5NSiMe2NPh2) (5a). A Pyrex
sample tube (20 mm o.d.) with a greaseless vacuum valve was
charged with 3a (123 mg, 0.234 mmol) and connected to a vacuum
line. Toluene (25 mL) was then introduced into the tube under high
vacuum by the trap-to-trap transfer technique. After sealing the tube
off from the vacuum line, the solution was irradiated for 30 min.
The tube was subsequently reopened under N2 in glovebox. After
evaporation of volatiles under reduced pressure, the residue was
extracted with pentane (5 mL × 2), and the extract was filtered
through a Celite pad. Cooling of the concentrated filtrate (ca. 3
mL) at -30 °C afforded orange crystals of 5a. Yield: 83 mg (0.17
1
3H × 2, p-Me), 7.08-7.19 (m, aromatic); H NMR (toluene-d8,
300 MHz, 258 K) δ -10.51 (s, 1H, RuH), 0.59, 0.62 (s, 3H × 2,
SiMe2), 1.51 (s, 15H, C5Me5), 2.21, 2.32 (s, 3H × 2, p-Me), 6.76
(m, 2H, aromatic), 7.01 (s, 1H, aromatic), 7.10 (s, 1H, aromatic),
7.17 (m, 2H, aromatic), 7.35 (m, 1H, aromatic); 13C{1H} NMR
(benzene-d6, 75.5 MHz, 298 K) δ 4.7, 9.7 (SiMe), 10.0 (C5Me5),
20.8, 21.0 (p-Me), 100.5 (C5Me5), 126.7, 130.2, 132.6, 143.7, 156.7
(aromatic), 205.4 (CO); (toluene-d8, 253 K) δ 4.8, 9.9 (SiMe), 10.1
(C5Me5), 20.3, 21.0 (p-Me), 100.5 (C5Me5), 111.8, 126.4, 130.3,
1
mmol, 71%). H NMR (300 MHz, benzene-d6) δ -0.02 (s, 6H,
3
SiMe2), 1.67 (s, 15H, C5Me5), 2.67 (d, JHH ) 3.0 Hz, 2H,

6124 Organometallics, Vol. 25, No. 26, 2006
Table 1. Crystallographic Data of 2a, 3a, 4j, and 5a
Iwata et al.
2a
3a
4j
5a
formula
cryst size (mm)
fw
C30H36FeN2OSi
0.30 × 0.30 × 0.30
524.56
C30H36FeN2OSi
0.20 × 0.20 × 0.20
524.56
C27H35NORuSi
0.30 × 0.30 × 0.20
518.72
C29H36FeN2Si
0.30 × 0.30 × 0.10
496.55
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
P21/n (No. 14)
11.4245(4)
16.9079(5)
16.8660(3)
92.431(2)
2676.0(1)
4
monoclinic
P21/a (No. 14)
17.1694(6)
9.0939(4)
18.5947(6)
109.099(2)
2743.5(2)
4
monoclinic
C2/c (No. 15)
40.5980(10)
8.70160(10)
15.1845(2)
107.912(2)
5104.18(15)
8
monoclinic
P21/n (No. 14)
16.1381(4)
10.0021(4)
16.4567(7)
100.529(1)
2611.6(2)
4
b (deg)
V (Å3)
Z
F000
1112
6.33
25124
6298 (0.039)
0.77 and 0.87
316
0.060, 0.119
0.033
1112
6.18
26166
6255 (0.056)
0.81 and 0.90
316
0.070, 0.132
0.051
2160
6.79
16824
5707 (0.064)
0.83 and 0.88
289
0.080, 0.198
0.062
1056
6.42
23665
6265 (0.039)
0.76 and 0.90
298
0.061, 0.121
0.033
µ(Mo KR) (cm-1
)
no. of reflns collected
no. of indep reflns (Rint
max. and min. transmn
no. of variables
R, Rw
)
R1 [I > 2σ(I)]
no. of reflns to calc R1
GOF
5370
0.99
0.25 and -0.51
4963
1.41
0.79 and -0.71
4671
1.13
0.90 and -2.02
5271
1.02
0.29 and -0.27
largest diff peak and hole (e Å-3
)
techniques (DIRDIF-94).30 All calculations were performed using
the teXsan crystallographic software package (Molecular Structure
Corporation). The structure of 4j was solved by Patterson and
Fourier transform methods using SHELXS-97 and refined by full
matrix least-squares techniques on all F2 data (SHELXL-97).31 All
non-hydrogen atoms were located and refined anisotropically.
Hydrogen atoms were placed at their geometrically calculated
positions. Details of the data collection and refinement are provided
in Table 1.
3
R-NC5H5), 3.36 (m, 2H, â-NC5H5), 5.48 (t, JHH ) 4.8 Hz, 1H,
3
3
γ-NC5H5), 6.93 (t, JHH ) 7.2 Hz, 2H, p-Ph), 7.10 (d, JHH ) 7.2
Hz, 4H, o-Ph), 7.19 (t, JHH ) 7.2 Hz, 4H, m-Ph); 13C{1H} NMR
3
(75.5 MHz, benzene-d6) δ -2.8 (SiMe2), 10.5 (C5Me5), 45.2 (R-
NC5H5), 78.5 (â-NC5H5), 85.0 (γ-NC5H5), 90.6 (C5Me5), 122.5 (p-
Ph), 125.4 (o-Ph), 129.2 (m-Ph), 149.0 (ipso-Ph); 29Si{1H} NMR
(59.6 MHz, benzene-d6) δ -14.2 (SiMe2); IR (benzene-d6, cm-1
)
no band for CO region; EI-MS (70 eV) m/z 496 (100, M+), 402
(42, M+ - Me - NC5H5), 305 (4, [C5H5NSiMe2NPh2]+), 283 (39),
270 (46, M+-SiMe2NPh2), 226 (34, [SiMe2NPh2]+). Anal. Calcd
for C29H36FeN2Si: C, 70.15; H, 7.31; N, 5.64. Found: C, 69.83;
H, 7.52; N, 5.68.
Supporting Information Available: Kinetic data for the
isomerization from 2a to 3a and CIF files for all crystal structures.
This material is available free of charge via the Internet at
http://pubs.acs.org.
X-ray Crystal Structure Determination of 2a, 3a, 4j, and 5a.
Single crystals of 2a, 3a, 4j, and 5a were obtained by cooling the
solutions at -30 °C. Intensity data for X-ray crystal structure
analysis were collected at 150 K using a Rigaku RAXIS-RAPID
imaging plate diffractometer with graphite-monochromated Mo KR
radiation. The data were corrected for Lorentz-polarization effects,
and numerical absorption corrections were applied on each crystal
shape. The structures of 2a, 3a, and 5a were solved by heavy-
atom Patterson methods (PATTY) and expanded using Fourier
OM060873N
(30) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.; De
Gelder, R.; Israel, R.; M. Smits, J. M. The DIRDIF-94 program system,
Technical Report for the Crystallography Laboratory; University of
Nijmegen: The Netherlands, 1994.
(31) (a) Sheldrick, G. M. SHELXS-97, Programs for Solving X-ray
Crystal Structures; University of Go¨ttingen, 1997. (b) Sheldrick, G. M.
SHELXL-97, Programs for Refining X-ray Crystal Structures; University
of Go¨ttingen, 1997.