Iron, ruthenium, and osmium complexes supported by the bis(silyl) chelate ligand (9,9-dimethylxanthene-4,5-diyl)bis(dimethylsilyl): Synthesis, characterization, and reactivity

Article abstract of DOI:10.1021/om700720s

The bis(silyl)-type bidentate ligand precursors xantsil-H₂ (la) and 2,7-di-t-butylxantsil-H₂ (1b) possessing the xanthene backbone were prepared by dilithiation of the 4,5-positions of 9,9-dimethylxanthene or 2,7-di-t-butyl-9,9-dimet

Full text of DOI:10.1021/om700720s

Organometallics 2007, 26, 5859-5866
5859
Iron, Ruthenium, and Osmium Complexes Supported by the
Bis(silyl) Chelate Ligand
(9,9-Dimethylxanthene-4,5-diyl)bis(dimethylsilyl): Synthesis,
Characterization, and Reactivity
Jim Josephus G. Minglana,† Masaaki Okazaki,‡ Kenji Hasegawa, Lung-Shiang Luh,
Nobukazu Yamahira, Takashi Komuro, Hiroshi Ogino,§ and Hiromi Tobita*
Department of Chemistry, Graduate School of Science, Tohoku UniVersity, Sendai 980-8578, Japan
ReceiVed July 19, 2007
The bis(silyl)-type bidentate ligand precursors xantsil-H2 (1a) and 2,7-di-t-butylxantsil-H2 (1b) possessing
the xanthene backbone were prepared by dilithiation of the 4,5-positions of 9,9-dimethylxanthene or
2,7-di-t-butyl-9,9-dimethylxanthene using n-BuLi in the presence of tetramethylethylenediamine (TMEDA)
followed by treatment with chlorodimethylsilane. According to X-ray diffraction analysis of 1b, the
xanthene core is close to planar as observed in the dihedral angle of 6.2(2)° between two least-square
planes of two aromatic rings in xanthene. UV irradiation of [Fe(CO)5] and 1a in dichloromethane provided
cis-[Fe(xantsil)(CO)4] (2), while thermal reactions of [M3(CO)12] (M ) Ru and Os) and 1a provided
cis-[M(xantsil)(CO)4] (M ) Ru (3) and Os (4)). In the course of the synthetic study on 3, formation of
[Ru3(xantsil)(µ-H)2(CO)10] (5) was confirmed and independently synthesized by the reaction of
[Ru3(CO)10(CH3CN)2] with 1a. Thermolysis of 5 and 1a at 120 °C for 13 min afforded 3, indicating its
intermediacy to 3. Refluxing the toluene solution of 3 for 3 h resulted in the replacement of three carbonyl
ligands with toluene to give [Ru(xantsil)(CO)(η6-toluene)] (6). Dissociation of the three carbonyl ligands
would be enhanced by the severe steric repulsion between the SiMe2 moiety and the three fac-carbonyl
ligands, high trans effect of silyl groups, and precoordination of the xanthene oxygen atom.
effects on catalytic activity and selectivity based on the rigidity
of the xanthene core and the large bite angle have been demon-
strated (Chart 1).1,5 We are now applying this unique backbone
of xanthene to the bis(silyl)-type bidentate ligand, (9,9-dimeth-
ylxanthene-4,5-diyl)bis(dimethylsilyl), or “xantsil” (Chart 1).
Complexation of a silyl silicon atom with a transition-metal
center has a marked effect on the properties of the metal
complex, attributable to the exceptionally strong σ-donor
character and high trans influencing character of the silyl group.6
Silyl groups are thus expected to be useful as ancillary ligands
suitable for preparing coordinatively unsaturated, electron-rich
Introduction
The design and fine-tuning of ancillary ligands are important
in the development of new transition-metal-catalyzed reactions.
Diphosphines (abbreviated to P^P), for example, have been
shown to influence the reactivity and selectivity of metal cen-
ters in a manner dependent on the bite angle.1 In Pt(P^P)
systems, the reactivity toward activation of C-H and C-X
bonds increases with decreasing the P-Pt-P angle,2 while in
the [Pt(H)(C2H4)(P^P)]+ systems, the introduction of diphos-
phines with a large bite angle accelerates the insertion of ethy-
lene into the Pt-H bond, consistent with the predicted transition
state for a widened P-Pt-P angle.3 High regioselectivity in
the rhodium-catalyzed hydroformylation of 1-alkenes can be
achieved by introducing diphosphines with a large bite angle.4
Several diphosphine ligands with a variety of xanthene-type
backbones (xantphos) have been developed, and the beneficial
(5) Kranenburg, M.; van der Burgt, Y. E. M.; Kamer, P. C. J.; van
Leeuwen, P. W. N. M. Organometallics 1995, 14, 3081. (b) Kranenburg,
M.; Delis, J. G. P.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Vrieze, K.;
Veldman, N.; Spek, A. L.; Goubitz, K.; Fraanje, J. J. Chem. Soc., Dalton
Trans. 1997, 1839. (c) Buhling, A.; Kamer, C. J.; van Leeuwen, P. W. N.
M.; Elgersma, J. W.; Goubitz, K.; Fraanje, J. Organometallics 1997, 16,
3027. (d) Kranenburg, M.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.
Eur. J. Inorg. Chem. 1998, 155. (e) Goedheijt, M. S.; Reek, J. N. H.; Kamer,
P. C. J.; van Leeuwen, P. W. N. M. Chem. Commun. 1998, 2431. (f) Goertz,
W.; Keim, W.; Vogt, D.; Englert, U.; Boele, M. D. K.; van der Veen, L.
A.; Kamer, P. C. J.; van Leeuwen, P. W. N. M. J. Chem. Soc., Dalton
Trans. 1998, 2981. (g) van der Veen, L. A.; Boele, M. D. K.; Bregman, F.
R.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Goubitz, K.; Fraanje, J.;
Schenk, H.; Bo, C. J. Am. Chem. Soc. 1998, 120, 11616.
(6) (a) Chatt, J.; Eaborn, C.; Ibekwe, S. Chem. Commun. 1966, 700. (b)
McWeeny, R.; Mason, R.; Towl, A. D. C. Discuss. Faraday Soc. 1969, 47,
20. (c) Chatt, J.; Eaborn, C.; Ibekwe, S. D.; Kapoor, P. N. J. Chem. Soc. A
1970, 1343. (d) Bentham, J. E.; Cradock, S.; Ebsworth, E. A. V. J. Chem.
Soc. A 1971, 587. (e) Hartley, F. R. Chem. Soc. ReV. 1973, 2, 163. (f)
Haszeldine, R. N.; Parish, R. V.; Setchfield, J. H. J. Organomet. Chem.
1973, 57, 279. (g) Yamashita, H.; Hayashi, T.; Kobayashi, T.; Tanaka, M.;
Goto, M. J. Am. Chem. Soc. 1988, 110, 4417. (h) Lichtenberger, D. L.;
Rai-Chaudhuri, A. J. Am. Chem. Soc. 1991, 113, 2923. (i) Levy, C. J.;
Puddephatt, R. J.; Vittal, J. J. Organometallics 1994, 13, 1559. (j) Brost,
R. D.; Bruce, G. C.; Joslin, F. L.; Stobart, S. R. Organometallics 1997, 16,
5669.
* Corresponding author. E-mail: tobita@mail.tains.tohoku.ac.jp.
† Institute of Chemistry, University of the Philippines, Diliman, Quezon
City 1101, Philippines.
‡ International Research Centre for Elements Science, Institute for
Chemical Research, Kyoto University, Uji Kyoto, 611-0011, Japan.
§ The Open University of Japan, Chiba, 261-8586, Japan.
(1) (a) van Leeuwen, P. W. N. M.; Kamer, P. C. J.; Reek, J. N. H.;
Dierkes, P. Chem. ReV. 2000, 100, 2741. (b) Kamer, P. C. J.; van Leeuwen,
P. W. N. M.; Reek, J. N. H. Acc. Chem. Res. 2001, 34, 895. (c) Freixa, Z.;
van Leeuwen, P. W. N. M. Dalton Trans. 2003, 1890. (d) Zuidema, E.;
van Leeuwen, P. W. N. M.; Bo, C. Organometallics 2005, 24, 3703.
(2) Hofmann, P.; Heiss, H.; Neiteler, P.; Mu¨ller, G.; Lachmann, J. Angew.
Chem., Int. Ed. Engl. 1990, 29, 880.
(3) (a) Thorn, D. L.; Hoffmann, R. J. Am. Chem. Soc. 1978, 100, 2079.
(b) Coussens, B. B.; Buda, F.; Oevering, H.; Meier, R. J. Organometallics
1998, 17, 795.
(4) Casey, C. P.; Whiteker, G. T.; Melville, M. G.; Petrovich, L. M.;
Gavney, J.; Powell, D. R. J. Am. Chem. Soc. 1992, 114, 5535.
10.1021/om700720s CCC: $37.00 © 2007 American Chemical Society
Publication on Web 10/20/2007

5860 Organometallics, Vol. 26, No. 24, 2007
Minglana et al.
Chart 1
Scheme 1
Figure 1. ORTEP drawing of 1b. Thermal ellipsoids are drawn at
the 50% probability level.
monohydrosilanes. The spectroscopic features of 1b closely
resemble those of 1a.
Single crystals of 1b suitable for X-ray diffraction analysis
were obtained by recrystallization from hot hexane. The
molecular structure of 1b is shown in Figure 1. The molecule
has a pseudo-C2 axis of symmetry through O and C17. The
xanthene core is close to planar, as indicated by the small
dihedral angle (6.2(2)°) between the two least-square planes of
the two aromatic rings. The interatomic distance between Si1
and Si2 is 4.624(2) Å.
Ultraviolet irradiation (λ > 300 nm) of [Fe(CO)5] and 1a in
dichloromethane provided cis-[Fe(xantsil)(CO)4] (2) as the main
product, which was purified by silica-gel flash chromatography
(eq 1). Slow evaporation of the eluent afforded colorless crys-
tals of 2 in 53% yield. The synthesis of 2 using [Fe(CO)5] or
[Fe2(CO)9] under thermal conditions was not successful due to
the thermal instability of the resulting Fe(II) complexes. The
ruthenium and osmium analogues, however, were obtainable
under thermal conditions. Refluxing the toluene solutions of
[M3(CO)12] and 3 equiv of 1a resulted in the formation of cis-
[M(xantsil)(CO)4] (M ) Ru (3), 34%; Os (4), 87%) as colorless
crystals (eq 2). The low isolated yield of 3 is attributable to the
further reaction of 3 with toluene (vide infra).
metal centers. However, the facile cleavage of metal-silicon
bonds via reductive elimination, nucleophilic attack at the silicon
atom, insertion, or σ-bond metathesis,7 have obstructed progress
in this area.8 The xantsil ligand with the xanthene backbone is
expected to prevent reactions that lead to such cleavage of the
metal-silicon bonds. In the present paper, the ligand precursor
xantsil-H2 (1) is synthesized and characterized by spectroscopy
and X-ray diffraction analyses. The coordination of xantsil with
group-8 transition metals in κ2Si,Si fashion can be achieved
through the reactions of [Fe(CO)5] or [M3(CO)12] (M ) Ru,
Os) with 1a under photochemical or thermal conditions. The
nature of the bis(silyl) ancillary ligand with the xanthene core
is discussed based on the crystal structures, dynamic behavior
in solution, and reactivity of the metal complexes. Part of this
work has been published previously in a preliminary form.9
Results and Discussion
The ligand precursors 1a and 1b were prepared by dilithiation
of the 4,5-positions of 9,9-dimethylxanthene or 2,7-di-t-butyl-
9,9-dimethylxanthene using n-BuLi in the presence of tetra-
methylethylenediamine (TMEDA) followed by treatment with
dimethylchlorosilane (Scheme 1). Analytically pure samples of
1a (96%) and 1b (42%) were obtained by subjecting the reaction
1
mixtures to silica-gel flash chromatography. In the H NMR
spectrum of 1a, the signal of SiMe2 appears at δ 0.43 as a
doublet coupled with the septet signal of SiH at δ 5.15 (J )
3.5 Hz). The 29Si{1H} NMR spectrum of 1a contains a
resonance at δ -22.2, the chemical shift characteristic of
(7) (a) Tilley, T. D. In The Chemistry of Organic Silicon Compounds;
Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1989; Chapter 24, p 1415.
(b) Tilley, T. D. In The Silicon-Heteroatom Bond; Patai, S., Rappoport, Z.,
Eds.; Wiley: New York, 1991; Chapters 9 and 10, pp 245 and 309. (c)
Eisen, M. S. In The Chemistry of Organic Silicon Compounds; Rappoport,
Z., Apeloig, Y., Eds.; Wiley: New York, 1998; Vol. 2, Chapter 35, p 2037.
(d) Corey, J. Y.; Braddock-Wilking, J. Chem. ReV. 1999, 90, 175. (e)
Okazaki, M.; Tobita, H.; Ogino, H. Dalton Trans. 2003, 493.
(8) (a) Brost, R. D.; Bruce, G. C.; Joslin, F. L.; Stobart, S. R.
Organometallics 1997, 16, 5669. (b) Stobart, S. R.; Zhou, X.; Cea-Olivares,
R.; Toscano, A. Organometallics 2001, 20, 4766. (c) Okazaki, M.; Tobita,
H.; Ogino, H. J. Chem. Soc., Dalton Trans. 1997, 3531. (d) Okazaki, M.;
Tobita, H.; Kawano, Y.; Inomata, S.; Ogino, H. J. Organomet. Chem. 1998,
553, 1. (e) Okazaki, M.; Ohshitanai, S.; Tobita, H.; Ogino, H. Chem. Lett.
2001, 952. (f) Okazaki, M.; Ohshitanai, S.; Tobita, H.; Ogino, H. Coord.
Chem. ReV. 2002, 226, 167 and references therein.
All three complexes exhibit similar NMR and IR spectro-
scopic features. In the IR spectra, four intense νCO bands are
apparent in the region of 1981-2100 cm-1, consistent with
the cis-ML2(CO)4 geometry of C2V symmetry. The 29Si{1H}
NMR spectra display resonances at δ 9.0 (2), -8.2 (3), and
(9) Tobita, H.; Hasegawa, K.; Minglana, J. J. G.; Luh, L-S.; Okazaki,
M.; Ogino, H. Organometallics 1999, 18, 2058.

Iron, Ruthenium, and Osmium Complexes
Organometallics, Vol. 26, No. 24, 2007 5861
Scheme 2
-31.7 (4). The trend is similar to that found for the group 8
metal complexes of cis-[M(SiMe3)2(CO)4] (M ) Fe (δ 26.6),
Ru (δ 2.1), and Os (δ -22.8)).10 At room temperature, each of
the 1H NMR signals of the SiMe and 9-CMe groups on xantsil
produces one singlet signal, indicating the existence of fluxional
behavior. Inversion of the puckered chelate ring is likely, as
shown in Scheme 2.9
The structures of 2, 3, and 4 were unequivocally determined
by X-ray crystal structure analysis (Figures 2-4). Selected
interatomic distances and angles are listed in Table 1. The two
mutually cis-silyl groups and four carbonyl ligands adopt a
distorted octahedral arrangement around the metal center. The
bite angles of Si-M-Si (94.9-97.5°) are widened slightly from
Figure 4. ORTEP drawing of cis-[Os(xantsil)(CO)4] (4). Thermal
ellipsoids are drawn at the 50% probability level, and hydrogen
atoms are omitted for clarity.
the ideal 90° by the formation of the eight-membered chelate
ring. The xanthene moiety is strongly bent, with a dihedral angle
of 43° between the least-square planes of the two aromatic rings
in the xantsil ligand. This is in contrast to the near-planar
arrangement of the xanthene core in the ligand precursor 1b,
demonstrating the flexibility of the xantsil ligand. The two axial
CO ligands are bent slightly toward the electron-releasing xantsil
ligand, as evidenced by the C1-M-C3 angles (158.8(3)-162.8-
(2)°), which are far from linear. Distortion from the octahedron
to a bicapped tetrahedron has been discussed in several previous
studies (Chart 2).11-13 Narrowing the trans L-M-L angle from
180° and widening the cis L-M-L angle leads to distortion of
the octahedron (A) to a bicapped tetrahedron (B). Hoffmann et
al. showed by extended Hu¨ckel calculations that σ-donors prefer
position D of the capping ligand in the bicapped tetrahedron
C, while σ-acceptors prefer position A.11a Complexes 2-4
approach the pseudo-bicapped tetrahedron, with the two silyl
groups of xantsil as σ-donors.
The most characteristic feature in the structures of 2-4 is
the exceptionally long metal-silicon bonds. These metal-
silicon bonds are the longest of such bonds reported in the
Cambridge Data Base (Fe-Si, 2.154-2.488 Å; Ru-Si, 2.177-
2.539 Å; Os-Si, 2.254-2.517 Å). The lengthening is attribut-
able to the special steric requirement of the xantsil ligand on
coordination to the metal center (Table 1). On κ2Si,Si-coordina-
tion, the xantsil ligand fixes two methyl groups C5 and C7 at
an extremely short interatomic distance (3.469(13)-3.490(9)
Å) compared to the sum of the effective van der Waals radii of
the two methyl groups (4.0 Å). The steric repulsion between
these methyl groups forces the other two methyl groups (C6
and C8) to move toward the carbonyl ligands. The observed
interatomic distances between C6 and O2 and between C8 and
O4 (3.203(12)-3.349(10) Å) are significantly shorter than the
sum of the van der Waals radii of the methyl group and oxygen
atom (3.4 Å), leading to considerable stretching of the metal-
silicon bonds.
Figure 2. ORTEP drawing of cis-[Fe(xantsil)(CO)4] (2). Thermal
ellipsoids are drawn at the 50% probability level, and hydrogen
atoms are omitted for clarity.
(10) Krentz, R.; Pomeroy, R. K. Inorg. Chem. 1985, 24, 2976.
(11) (a) Hoffmann, R.; Howell, J. M.; Rossi, A. R. J. Am. Chem. Soc.
1976, 98, 2484. (b) Kubacek, P.; Hoffmann, R. J. Am. Chem. Soc. 1981,
103, 4320.
(12) Templeton, J. L.; Winston, P. B.; Ward, B. C. J. Am. Chem. Soc.
1981, 103, 7713.
(13) Kamata, M.; Hirotsu, K.; Higuchi, T.; Tatsumi, K.; Hoffmann, R.;
Yoshida, T.; Otsuka, S. J. Am. Chem. Soc. 1981, 103, 5772.
Figure 3. ORTEP drawing of cis-[Ru(xantsil)(CO)4] (3). Thermal
ellipsoids are drawn at the 50% probability level, and hydrogen
atoms are omitted for clarity.

5862 Organometallics, Vol. 26, No. 24, 2007
Minglana et al.
Table 1. Summary of Selected Interatomic Distances and Angles for cis-[M(xantsil)(CO)4] (M ) Fe (2), Ru(3), Os(4))
2
3
4
Selected Interatomic Distances (Å)
M-Si1, M-Si2
Si1‚‚‚Si2, C5‚‚‚C7
C6‚‚‚O2, C8‚‚‚O4
2.497(3), 2.489(3)
3.747(2), 3.469(13)
3.203(12), 3.231(13)
2.562(2), 2.564(2)
3.786(2), 3.490(9)
3.320(9), 3.349(10)
2.5750(18), 2.5689(18)
3.790(2), 3.479(10)
3.274(10), 3.348(9)
Selected Interatomic Angles (deg)
Si1-M-Si2, Si1-M-C1
Si1-M-C2, Si1-M-C3
Si1-M-C4, Si2-M-C1
Si2-M-C2, Si2-M-C3
Si2-M-C4, C1-M-C2
C1-M-C3, C1-M-C4
C2-M-C3, C2-M-C4
C3-M-C4
97.45(8), 84.0(2)
85.8(3), 83.4(3)
176.6(3), 87.3(2)
173.9(3), 77.6(3)
85.9(3), 98.2(4)
158.8(3), 96.1(3)
97.8(4), 90.9(4)
97.5(4)
95.26(6), 84.5(2)
85.8(2), 85.4(2)
178.5(2), 88.2(2)
174.9(2), 78.9(2)
85.8(2), 96.8(3)
162.8(2), 94.4(3)
96.3(3), 93.2(3)
95.9(3)
94.90(6), 83.76(19)
85.2(2), 86.6(2)
178.5(2), 87.28(18)
174.8(2), 78.3(2)
85.6(2), 97.9(3)
161.9(3), 94.8(3)
96.5(3), 94.4(3)
95.0(3)
Dihedral Angles between Two Aromatic Rings in Xantsil (deg)
43.4(3) 43.3(2)
43.3(2)
Chart 2
A direct reaction between [Ru3(CO)12]and a bis(hydrosilyl)
ligand precursor has been reported in the preparation of [Ru3-
(µ-SiMe2C5H4FeC5H4SiMe2)(µ-H)2(CO)10].16 Unlike the xantsil
complexes, however, the reaction of [Ru3(CO)12]with this 1,1′-
bis(dimethylsilyl)ferrocene ligand precursor was found to be
highly dependent on the ratio of the reactants. A 3:1 molar ratio
of [Ru3(CO)12] to the ligand precursor was required to obtain
the mononuclear complex cis-[Ru(κ2Si,Si-SiMe2C5H4FeC5H4-
SiMe2)(CO)4], while an equimolar ratio of reactants gave the
trinuclear cluster exclusively.
Scheme 3
Synthesis using labile trinuclear ruthenium clusters has also
been reported as part of the preparation of other silyl trinuclear
clusters such as [Ru3(SiR3)2(µ-H)2(µ-C4H4N2)(CO)8] (R ) Et,
Ph) through the reaction of the activated [Ru3(µ-C4H4N2)(µ-
CO)3(CO)7] with tertiary silanes in refluxing THF.17 Because
of the high lability of acetonitrile ligands, [Ru3(CO)10(NCMe)2]
is convenient for the synthesis of 5 without heating.
An ORTEP drawing of the 1:1 aggregate of [Ru(xantsil)-
(CO)4] (3) and [Ru3(xantsil)(µ-H)2(CO)10] (5) is shown in
Figure 5. There is no significant interaction between the two
molecules. The structural features of fragment 3 are essentially
the same as those observed for 3 alone. The ORTEP drawing
of fragment 5 and selected interatomic distances and angles are
shown in Figure 6. The three ruthenium atoms form a triangle
with xantsil as a bridging ligand between Ru2 and Ru3. The
Ru-Ru bonds (2.94-3.16 Å) are considerably longer than those
of Ru3(CO)12 (2.854 Å)18 and are comparable to those of the
related Ru3 clusters.16,19 The silyl groups are bound to the
ruthenium atoms in the plane of a Ru3 triangle. All carbonyl
ligands are terminal. The xanthene moiety is close to planar,
exhibiting a dihedral angel of 7.7(1)° between the least-square
planes of two aromatic rings in xantsil. The Ru2-Si4 and Ru3-
Si3 bond lengths are consistent with the standard equilibrium
bond length. Although the two bridging hydrogen atoms could
not be located crystallographically, their existence is suggested
by the NMR spectroscopic data (vide infra). These are assigned
to the bridging positions between the two longest Ru-Ru bonds;
Ru2-Ru3 (3.0123(3) Å) and Ru2-Ru4 (3.1600(3) Å), consis-
tent with several reports on the elongation of Ru-Ru bonds
when bridged by a hydrogen atom.17,19,20 Moreover, there is a
Ru(dCHPh)Cl2(xantphos) has been reported to have a bite
angle of 161°, indicative of the trans configuration of two
phosphine parts in xantphos.14 Silyl groups in xantsil, however,
are expected to exhibit the exceptional electron-releasing and
trans influencing character. Such features would prevent the
trans-configuration of two silyl groups in xantsil.15
The synthetic study of 3 revealed the formation of a trinuclear
ruthenium cluster [Ru3(xantsil)(µ-H)2(CO)10] (5), which was
obtained by the direct reaction of [Ru3(CO)12] with 1a in
refluxing toluene for 15 min and by the reaction of [Ru3(CO)10-
(CH3CN)2] with 1a at room temperature (Scheme 3). In the
direct reaction of [Ru3(CO)12], the trinuclear complex 5 was
formed in 19% yield together with the mononuclear complex 3
(19%) and unreacted [Ru3(CO)12]. The isolation of 5 by silica
gel flash chromatography was not successful because of the
decomposition of 5. Recrystallization of the crude product from
toluene afforded colorless crystals of 3 along with large red
crystals identified as aggregates of 3 and 5 at a 1:1 ratio. The
synthesis of 5 via [Ru3(CO)10(NCMe)2] afforded reddish-orange
crystals of 5 in 63% yield.
(14) Nieczypor, P.; van Leeuwen, P. W. N. M.; Mol, J. C.; Lutz, M.;
Spek, A. L. J. Organomet. Chem. 2001, 625, 58.
(16) Kotani, S.; Tanizawa, T.; Adachi, T.; Yoshida, T.; Sonogashira, K.
Chem. Lett. 1994, 1665.
(17) Cabeza, J. A.; Franco, R. J.; Llamazares, A.; Riera, V.; Bois, C.;
Jeannin, Y. Inorg. Chem. 1993, 32, 4640.
(18) (a) Mason, R.; Rae, A. I. M. J. Chem. Soc. A 1968, 778. (b)
Churchill, M. R.; Hollander, F. J.; Hutchinson, J. P. Inorg. Chem. 1977,
16, 2655.
(19) Klein, H.-P.; Thewalt, U.; Herrmann, G.; Su¨ss-Fink, G.; Moinet,
C. J. Organomet. Chem. 1985, 286, 225.
(15) The X-ray characterized trans-bis(silyl) complexes are very lim-
ited: (a) Shimada, S.; Tanaka, M.; Honda, K. J. Am. Chem. Soc. 1995,
117, 8289. (b) Kim, Y.-J.; Park, J.-I.; Lee, S.-C.; Osakada, K.; Tanabe, M.;
Choi, J.-C.; Koizumi, T.; Yamamoto, T. Organometallics 1999, 18, 1349.
(c) Wu, Z.; Diminnie, J. B.; Xue, Z. J. Am. Chem. Soc. 1999, 121, 4300.
(d) Qiu, H.; Cai, H.; Woods, J. B.; Wu, Z.; Chen, T.; Yu, X.; Xue, Z.-L.
Organometallics 2005, 24, 4190.

Iron, Ruthenium, and Osmium Complexes
Organometallics, Vol. 26, No. 24, 2007 5863
Scheme 4
Tc ) 307 K), the barrier at 307 K is calculated by the
coalescence point method to be ∆Gq ) 68 kJ mol-1. This
307
dynamic process is also likely to include the inversion of the
puckered chelate ring as proposed for the dynamic behavior of
2, 3, and 4. Moreover, the 29Si{1H} NMR spectrum displays
one resonance at δ 7.2. Another dynamic process of 5, yielding
two equivalent Ru(CO)3(SiMe2) moieties, is thus considered to
be too fast to be detected by NMR spectroscopy (Scheme 4).
The possibility of 5 as an intermediate leading to the for-
mation of 3 was further investigated by monitoring the thermal
Figure 5. ORTEP drawing of the 1:1 aggregate of cis-[Ru(xantsil)-
(CO)4] (3) and [Ru3(xantsil)(µ-H)2(CO)10] (5) at the 50% probability
level. Hydrogen atoms are omitted for clarity.
1
reaction of 5 with 1a (2.8 equiv) by H NMR spectroscopy.
Thermolysis at 120 °C for 13 min was sufficient to achieve
complete consumption of 5 to give 3 in 28% yield based on
the number of carbonyl ligands (eq 3). As thermolysis of 5 in
the absence of 1a did not give 3, the path leading to 3 starts
from 5 and 1a.
Figure 6. ORTEP drawing of the [Ru3(xantsil)(µ-H)2(CO)10] (5)
fragment at the 50% probability level. Selected interatomic dis-
tances (Å) and angles (deg): Ru2-Ru3, 3.0123(3); Ru3-Ru4,
2.9378(4); Ru2-Ru4, 3.1600(3); Ru2-Si4, 2.4854(8); Ru3-Si3,
2.4479(9); C24‚‚‚C31, 4.433(5); C28‚‚‚C32, 2.998(5); Ru2-Ru3-
Ru4, 64.144(8); Ru3-Ru4-Ru2, 59.073(8); Ru4-Ru2-Ru3,
56.783(8).
Consistent with the general stability of organometallic com-
plexes, the xantsil-iron complex 2 was unstable and thus difficult
to handle as a starting material, while the xantsil-osmium com-
plex 4 was too stable to allow further transformation reactions.
The xantsil-ruthenium complex 3 exhibits moderate reactivity:
The thermal reaction of 3 in refluxing toluene for 3 h resulted
in the replacement of three carbonyl ligands with toluene to
give [Ru(xantsil)(CO)(η6-toluene)] (6) in 93% yield (eq 4).
Complex 6 was uniquely characterized by NMR and X-ray
diffraction data (Figure 7).9
large difference between the interatomic distances of
C24‚‚‚C31 (4.433(5) Å) and C28‚‚‚C32 (2.998(5) Å), clearly
indicating the presence of a hydrogen atom bridging the
Ru2-Ru4 bond and the absence of such a bridging atom on
Ru3-Ru4. The steric requirement for the bridging hydrogen
atom increases the distance between carbonyl ligands
C24-O7 and C31-O14, whereas the C28-O11 to C32-O15
distance is unaffected.
The appearance of several bands in the 1986-2116 cm-1
region of the IR spectrum indicates that all carbonyl ligands
are terminal. The 1H NMR spectrum of 5 exhibits singlet signals
at δ -16.27 and -14.94, indicating the presence of two
chemically inequivalent bridging hydrido ligands. The dynamic
behavior of 5 was examined in toluene-d8 by variable temper-
ature 1H NMR study. At 295 K, the two singlets for the methyl
groups in SiMe2 and other two singlets for those in 9,9-CMe2
appear as broad signals. On lowering the temperature, these
signals become sharp. On increasing the temperature, each of
them coalesces and finally becomes a sharp singlet. The
coalescence point for the 9,9-CMe2 moiety could not be
determined owing to overlap with other signals. From the data
for the exchange of SiMe2 groups (∆ν (at 215 K) ) 17.6 Hz,
In contrast to 3, no analogous replacement of CO was detected
for bis(silyl)ruthenium(II) complex 7 upon treatment in toluene-
d8 at 130 °C for 2 days (eq 5), implying that the xantsil ancillary
ligand is crucial in the substitution reaction of three CO groups
with arene. A plausible mechanism involves the initial formation
of [Ru(κ3Si,Si,O-xantsil)(CO)3] through the dissociation of one
carbonyl ligand, followed by the intramolecular coordination
of the xanthene oxygen atom. Dissociation of the carbonyl ligand
would be enhanced by the severe steric repulsion between the
SiMe2 moiety and the three fac-carbonyl ligands and/or pre-
coordination of the xanthene oxygen atom to lower the activation
barrier. The incoming toluene interacts with the coordinatively
(20) Churchill, M. R.; Deboer, B. G.; Rotella, F. J. Inorg. Chem. 1976,
15, 1843.

5864 Organometallics, Vol. 26, No. 24, 2007
Minglana et al.
vacuum for the sealed-tube reactions. 9,9-Dimethylxanthene,22 2,7-
di-t-butyl-9,9-dimethylxanthene,23 [Ru3(CO)12],24 and [Os3(CO)12]25
were prepared according to literature methods. Tetracarbonyl{4,5-
dimethylphenylene-1,2-bis(dimethylsilyl)}ruthenium (7) was syn-
thesized by the synthetic procedure for tetracarbonyl{phenylene-
1,2-bis(dimethylsilyl)}ruthenium.26 Other reagents were purchased
from commercial sources and used without further purification.
NMR measurements were performed on a Bruker ARX-300 or
AVANCE-300 NMR spectrometer at room temperature unless
1
otherwise stated. H NMR spectra were referenced to Si(CH3)4
through the residual peaks of the employed solvents, 13C{1H} and
29Si{1H} NMR spectra were referenced to external Si(CH3)4 at δ
0.0, and 31P NMR spectra were referenced to external 85% H3PO4
at δ 0.0. IR spectra were obtained on a Horiba FT-200 or FT-730
spectrophotometer. Mass spectra were measured on a JEOL HX110
or Hitachi M-2500S mass spectrometer.
Figure 7. ORTEP drawing of [Ru(xantsil)(η6-toluene)(CO)] (6)
at the 50% probability level. Selected interatomic distances (Å)
and angles (deg): Ru-Si1, 2.422(2); Ru-Si2, 2.420(2); Ru-C1,
1.815(6); Ru-C2, 2.327(5); Ru-C3, 2.294(6); Ru-C4, 2.287(6);
Ru-C5, 2.320(6); Ru-C6, 2.334(6); Ru-C7, 2.314(5); Si1-Ru-
Si2, 94.81(6).
4,5-Bis(dimethylsilyl)-9,9-dimethylxanthene (1a). To a mixture
of 9,9-dimethylxanthene (14.0 g, 66.6 mmol), TMEDA (21.3 mL,
133 mmol) in diethyl ether (270 mL), and hexane (200 mL) was
added a solution of n-BuLi (108 mL of 1.48 M solution in hexane,
160 mmol) diluted with hexane (200 mL) in a dropwise manner
over a period of 1 h. The mixture was then heated to 40 °C for 3
h, causing the solution to become deep red in color. After cooling
the solution to 0 °C, HSiMe2Cl (15.1 g, 160 mmol) in hexane (130
mL) was added to the solution over a period of 90 min under
constant stirring, causing the solution to become deep red to yellow
in color. After further stirring the solution at room temperature for
30 min, the reaction mixture was placed in a separatory funnel and
washed with distilled water. The organic layer was dried over
magnesium sulfate, and the volatiles were removed under vacuum.
Purification of the viscous yellow residue by flash chromatography
(silica gel, hexane) followed by recrystallization from hot hexane
gave colorless crystals of 1a. Yield: 20.9 g (96%). 1H NMR (300
unsaturated Ru(II) species derived from the facile dissociation
of the xanthene oxygen atom and finally replaces with three
carbonyl ligands to give 6. A xanthene-based diphosphine ligand
has been known to function as a κ3P,P,O-terdentate ligand
toward transition metals.5e,21
3
MHz, benzene-d6): δ 0.43 (d, J ) 3.5 Hz, 12H, SiMe2), 1.42 (s,
3
3
6H, 9-Me), 5.15 (septet, J ) 3.5 Hz, 2H, SiH), 6.99 (t, J ) 7.5
Hz, 2H, xantsil 2,7-H), 7.24 (dd, 3J ) 1.7, 4J ) 7.4 Hz, 2H, xantsil
1,8-H or 3,6-H), 7.32 (dd, 3J ) 1.7, 4J ) 7.4 Hz, 2H, xantsil 1,8-H
or 3,6-H). 13C{1H} NMR (75.5 MHz, benzene-d6): δ -3.3 (SiMe2),
32.8 (9-Me), 34.2 (9-C), 123.4, 124.7, 128.4, 129.4, 133.8, 155.1
(aromatic carbons). 29Si{1H} NMR (59.6 MHz, benzene-d6): δ
-22.2. IR (hexane, cm-1): 2119 (m) (νSiH), 2158s (νSiH). Mass
(FAB, Xe, m-nitrobenzyl alcohol matrix) m/z 326 (M+, 5), 311
(M+- CH3, 100). Anal. Calcd for C19H26OSi2: C, 69.88; H, 8.02.
Found: C, 70.02; H, 7.91.
4,5-Bis(dimethylsilyl)-2,7-di-tbutyl-9,9-dimethylxanthene (1b).
A method similar to that for 1a was employed for the preparation
of colorless crystals of 1b using n-BuLi (16.2 mL of 1.48 M solution
in hexane, 24 mmol), 2,7-di-t-butylxanthene (3.22 g, 10.0 mmol),
TMEDA (3.20 mL, 20.0 mmol), and HSiMe2Cl (2.27 g, 24.0
mmol). Yield: 1.84 g (42%). 1H NMR (300 MHz, benzene-d6): δ
0.50 (d, 3J ) 3.7 Hz, 12H, SiMe2), 1.33 (s, 18H, tBu), 1.60 (s, 6H,
Conclusion
Group-8 transition-metal mononuclear carbonyl complexes
supported by the bis(silyl) ligand (xantsil) were successfully
prepared by reactions between the appropriate metal carbonyls
and xantsil-H2 (1a) under thermal or photochemical conditions.
A Ru3 cluster with xantsil was also synthesized from Ru3(CO)12
or Ru3(CO)10(CH3CN)2. Spectroscopic and X-ray diffraction
analyses show that the eight-membered chelate ring of xantsil
induces steric crowding among the SiMe2 groups and the three
fac-carbonyl ligands, resulting in unusually long M-Si bonds
and facile replacement of three carbonyl ligands with arene.
The electronic effect of the strongly σ-donating silyl groups in
xantsil is proposed as the cause of distortion from the expected
octahedron to the bicapped-tetraheron. The steric requirement
and electronic effect of xantsil may be applicable in the
development of new types of metal-mediated catalytic reactions.
In [Ru3(xantsil)(µ-H)2(CO)10] (5), xantsil serves as a bridging
ligand to a Ru-Ru bond of the Ru3 triangle and is likely to
help prevent fragmentation. The preparation of the trinuclear
ruthenium cluster is particularly significant since Ru3(CO)12 and
its derivatives are frequently involved in metal-catalyzed
transformation reactions.
(21) (a) Sandee, A. J.; van der Veen, L. A.; Reek, J. N. H.; Kamer, P.
C. J.; Lutz, M.; Spek, A. L.; van Leeuwen, P. W. N. M. Angew. Chem.,
Int. Ed. 1999, 38, 3231. (b) Zuideveld, M. A.; Swennenhuis, B. H. G.;
Boele, M. D. K.; Guari, Y.; van Strijdonck, G. P. F.; Reek, J. N. H.; Kamer,
P. C. J.; Goubitz, K.; Fraanje, J.; Lutz, M.; Spek, A. L.; van Leeuwen, P.
W. N. M. Dalton Trans. 2002, 2308.
(22) (a) Corey, E. J.; Chaykovsky, M. J. Am. Chem. Soc. 1965, 87, 1345.
(b) Chanzan, J. B.; Ourisson, G. Bull. Soc. Chim. Fr. 1968, 4, 1384. (c)
Bavin, P. M. G. Can. J. Chem. 1960, 38, 882.
(23) Nowick, J. S.; Ballester, P.; Ebmeyer, F.; Rebek, J., Jr. J. Am. Chem.
Soc. 1990, 112, 8902.
Experimental Section
(24) (a) Eady, C. R.; Jackson, P. F.; Johnson, B. F. G.; Lewis, J.;
Malatesta, M. C.; Mcpartlin, M.; Nelson, W. J. H. J. Chem. Soc., Dalton
Trans. 1980, 383. (b) Bruce, M. I.; Jensen, C. M.; Jones, N. L.; Inorg.
Synth. 1989, 26, 259.
(25) Gade, L. Z., Johnson, B. F. G., Lewis, J., Loveday, P. A., Herrmann,
W. A., Eds. Synthetic Methods of Organometallic and Inorganic Chemistry;
Thieme Medical Publishers: Stuttgart, Germany, 1987; 7, 28.
(26) Fink, W. HelV. Chim. Acta 1976, 59, 606.
General. All manipulations were performed under an inert
atmosphere of dry argon or nitrogen or under high vacuum. Diethyl
ether, hexane, and toluene were distilled from sodium-benzophenone
ketyl, and dichloromethane was distilled from CaH2. Benzene-d6
and cyclohexane-d12 were dried over activated 4 Å molecular sieves
or over a potassium mirror and transferred to an NMR tube under

Iron, Ruthenium, and Osmium Complexes
Organometallics, Vol. 26, No. 24, 2007 5865
9-Me2), 5.21 (septet, 3J ) 3.7 Hz, 2H, SiH), 7.54 (d, 4J ) 2.3 Hz,
2CO - Me, 14), 544 (M+- 3CO, 23), 528 (M+- 3CO - Me -
H, 100). Exact MS (70 eV, DEI) m/z calcd for C23H24O5Si2Os,
628.0777; found, 628.0756.
4
2H, 1,8-H or 3,6-H), 7.56 (d, J ) 2.3 Hz, 2H, 3,6-H). 13C{1H}
NMR (75.5 MHz, benzene-d6): δ -3.2 (SiMe2), 31.7 (CMe3), 33.3
(9,9-Me2), 34.5, 34.8 (9-C, CMe3), 124.1, 125.2, 128.7, 130.6, 153.3
(aromatic carbons). 29Si{1H} NMR (59.6 MHz, benzene-d6): δ
-21.3. IR (KBr, cm-1): 2156 (s) (νSiH). Mass (EI, 70 eV) m/z 438
(M+, 10), 423 (M+- CH3, 100). Anal. Calcd for C27H42OSi2: C,
73.90; H, 9.65. Found: C, 73.67; H, 9.68.
Preparation of [Ru3(xantsil)(µ-H)2(CO)10] (5) from 1a and
Ru3(CO)12. Ru3(CO)12 (1.10 g, 1.72 mmol) and 1a (1.69 g, 5.18
mmol) were dissolved in toluene (20 mL) and the solution was
heated to 120 °C for 15 min. The resulting red reaction mixture
was then allowed to cool to room temperature. Volatiles were
removed under reduced pressure to give an orange oil, which was
dissolved in toluene and stored at -78 °C for one week to give a
mixture of small colorless crystals of 3 and large red crystals
identified as a 1:1 aggregate of 3 and Ru3(xantsil)(µ-H)2(CO)10
(5). The large crystals (0.92 g) containing 3 and 5 were sep-
arated manually from the finer crystals of 3 (0.25 g). Yield of 3:
0.52 g (19%). Yield of 5: 0.29 g (19%). Anal. Calcd for
C52H50O16Si4Ru4 (3‚5): C, 43.15; H, 3.48. Found: C, 43.38; H,
3.74.
cis-[Fe(xantsil)(CO)4] (2). A dichloromethane solution (1.5 mL)
of Fe(CO)5 (196 mg, 1.00 mmol) and 1a (98 mg, 0.30 mmol) was
irradiated under a medium-pressure Hg lamp (450 W) for 5 h. The
insoluble Fe2(CO)9 byproduct was then removed by filtration, and
the filtrate was concentrated and subjected to silica gel column
chromatography. Complex 2 was eluted with a 3:1 mixture of
hexane and diethyl ether. Evaporation of the eluent under reduced
pressure gave colorless crystals of 2. Yield: 79 mg (53%). 1H NMR
(300 MHz, benzene-d6): δ 0.88 (s, 12H, SiMe2), 1.42 (s, 6H,
9-Me2), 7.04 (t, 3J ) 7.5 Hz, 2H, xantsil 2,7-H), 7.22 (br. d, 2H, 3J
Preparation of [Ru3(xantsil)(µ-H)2(CO)10] (5) from 1a and
[Ru3(CO)10(NCMe)2]. (a) To a dichloromethane (100 mL) solution
of Ru3(CO)12 (0.100 g, 0.157 mmol) and 1a (0.610 g, 1.87 mmol)
cooled at -78 °C was added an acetonitrile (10 mL) solution of
Me3NO (38 mg, 0.051 mmol) in a dropwise manner. The reaction
mixture was returned naturally to room temperature and then stirred
for 4 h. The resulting orange solution was evaporated to dryness
and the residue extracted with toluene (50 mL). The solvent was
removed from the extract under vacuum, and the residue was further
extracted with hexane (35 mL). Cooling of the concentrated solution
to -48 °C gave reddish-orange crystals of 5. Yield: 90 mg (63%).
1H NMR (C6D6): δ -16.27, -14.94 (s, s, 1H, 1H, RuH), 0.97,
1.07 (s, s, 6H, 6H, SiMe2), 1.42, 1.45 (s, s, 3H, 3H, 9,9-Me2), 7.02
3
) 7.5 Hz, 2H, xantsil 1,8-H or 3,6-H), 7.25 (br. d, 2H, J ) 7.5
Hz, 2H, xantsil 1,8-H or 3,6-H). 13C{1H} NMR (75.5 MHz,
benzene-d6): δ 6.9 (SiMe2), 27.0 (9,9-CMe2), 36.3 (9,9-CMe2),
124.1, 126.0, 131.1, 131.2,133.6, 158.3 (aromatic carbons), 206.6,
208.4 (CO). 29Si{1H} NMR (C6D6): δ 9.0. IR (KBr, cm-1): 1981
(s), 1994 (s), 2011 (s), 2069 (s) (νCO). Mass (FAB, Xe, m-
nitrobenzyl alcohol matrix) m/z 493 (M+ + 1, 4), 478 (M+- Me
+ 1, 12), 464 (M+- CO, 12), 436 (M+- 2CO, 11), 408 (M+-
3CO, 100), 380 (M+- 4CO, 66). Anal. Calcd for C23H24O5Si2Fe:
C, 56.10; H, 4.91. Found: C, 55.85; H, 5.18.
cis-[Ru(xantsil)(CO)4] (3). Ru3(CO)12 (1.00 g, 1.56 mmol) and
1a (1.23 g, 3.77 mmol) were dissolved in toluene (200 mL) and
the solution heated to 120 °C. After 90 min, the initial red color of
the solution changed to dark brown, and the thin-layer chromato-
graphic (TLC) spot of 1a disappeared. Removal of volatiles under
vacuum gave a dark brown residue which was subjected to flash
chromatography (silica gel, hexane/toluene ) 3:1) to give a mixture
of 3 and Ru3(CO)12 (1.00 g) as the first fraction and a mixture of
1a and an unidentified brown product (0.40 g) as the second
fraction. Recrystallization of the former from hot hexane afforded
pure 3 as colorless crystals. Yield: 700 mg (34%). 1H NMR (300
MHz, benzene-d6): δ 0.88 (s, 12H, SiMe2), 1.45 (s, 6H, 9,9-Me2),
4
(t, 3J ) 7.5 Hz, 2H, 2,7-H), 7.27, 7.49 (dd, dd, J ) 1.6, 3J ) 7.5
Hz, 4H, 1,3,6,8-H). 13C{1H} NMR (C6D6): δ 9.1, 11.0 (SiMe2),
32.4, 33.3, 34.2 (9-C, 9,9-Me2), 123.4, 128.3, 130.0, 130.7, 132.6,
154.7 (aromatic carbons), 191.8, 201.5, 203.2 (CO). 29Si{1H} NMR
(C6D12): δ 7.2. IR (KBr): 2116 (m), 2100 (w), 2085 (m), 2069
(w), 2056 (s), 2040 (s), 2025 (s), 2011 (w), 1998 (w), 1986 (w)
(CO, cm-1). Mass (FAB, Xe, m-nitrobenzyl alcohol matrix): m/z
911 (M+, 5), 827 (M+- 3CO, 10), 399 (100).
Monitoring the Reaction of 5 and 1a. A Pyrex NMR tube was
charged with 5 (1.0 mg, 1.1 µmol), 1a (1.0 mg, 3.1 µmol), and
Si(SiMe3)4 (internal standard) and connected to the vacuum line.
Toluene-d8 (0.5 mL)was introduced into the tube by the trap-to-
trap transfer technique. The sample was then placed in an oil bath
and heated to 120 °C, and the reaction was monitored by NMR
spectroscopy.
3
4
3
7.08 (t, J ) 7.3 Hz, 2H, xantsil 2,7-H), 7.24 (dd, J ) 1.4, J )
4
3
7.3 Hz, 2H, xantsil 1,8-H or 3,6-H), 7.32 (dd, J ) 1.4, J ) 7.3
Hz, 2H, xantsil 1,8-H or 3,6-H). 13C{1H} NMR (75.5 MHz,
benzene-d6): δ 7.0 (SiMe2), 27.3 (9-Me), 36.1 (C-Me2), 123.8,
125.5, 131.0, 131.8,133.3, 158.1 (aromatic carbons), 190.7, 197.7
(CO). 29Si{1H} NMR (59.6 MHz, benzene-d6): δ -8.2. IR (hexane,
cm-1): 2015 (s), 2033 (s), 2042 (s), 2098 (s) (νCO). Mass (EI, 70
eV) m/z 538 (M+, 3), 510 (M+- CO, 39), 482 (M+- 2CO, 14),
454 (M+- 3CO, 100). Anal. Calcd for C23H24O5Si2Ru: C, 51.38;
H, 4.50. Found: C, 51.48; H, 4.47.
[Ru(xantsil)(CO)(η6-C6H5CH3)] (6). A solution of 3 (560 mg,
1.04 mmol) in toluene (140 mL) was refluxed in an oil bath at 120
°C for 3 h. After removal of the solvent, recrystallization of the
residue from hot toluene afforded 6 as pale yellow crystals. Yield:
1
526 mg (93%). H NMR (C6D12): δ 0.58, 0.63 (s, s, 6H, 6H,
cis-[Os(xantsil)(CO)4] (4). A toluene (6.0 mL) solution of Os3-
(CO)12 (75 mg, 0.083 mmol) and 1a (95 mg, 0.29 mmol) was heated
at 125 °C for 1 day. After cooling to room temperature, volatiles
were removed under vacuum. Purification of the brown residue by
silica gel flash chromatography with hexane/toluene eluent (hexane/
toluene ) 3:1) and subsequent recrystallization from hot hexane
and toluene (4:1) gave 4 as colorless crystals. Yield: 45 mg (87%).
1H NMR (300 MHz, benzene-d6): δ 0.95 (s, 12H, SiMe2), 1.45 (s,
6H, 9,9-Me2), 7.06 (t, 3J ) 7.4 Hz, 2H, xantsil 2,7-H), 7.21 (dd, 4J
SiMe2), 1.39, 1.82 (s, s, 3H, 3H, 9,9-Me2), 1.77 (s, 3H, C6H5Me),
3
3
3.79 (t, J ) 6.1 Hz, 1H, toluene p-H), 4.87 (t, J ) 6.1 Hz, 2H,
toluene m-H), 5.45 (d, 3J ) 6.1 Hz, 2H, toluene o-H), 6.99 (t, 3J )
4
3
7.3 Hz, 2H, xantsil 2,7-H), 7.22, 7.24 (dd, dd, J ) 1.4, J ) 7.3
Hz, 4H, xantsil 1,3,6,8-H). 13C{1H} NMR (C6D12): δ 4.4, 9.5, 20.4,
23.1, 31.0, 37.0 (alkyl C), 94.3, 97.6, 100.1, 109.9 (C6H5Me), 123.0,
123.8, 129.6, 134.6, 139.0, 159.4 (xanthene), 201.0 (CO). 29Si{1H}
NMR (C6D12): δ 12.6. IR (KBr): 1913 (vs, CO) 1386 (s) cm-1
.
3
4
Mass (EI, 70 eV) m/z 546 (M+, 65), 454 (M+ - C6H5Me, 100).
Anal. Calcd for C27H32O2Si2Ru: C, 59.42; H, 5.91. Found: C,
59.48; H, 5.81.
) 1.4, J ) 7.4 Hz, 2H, xantsil 1,8-H or 3,6-H), 7.26 (dd, J )
1.4, 3J ) 7.4 Hz, 2H, xantsil 1,8-H or 3,6-H). 13C{1H} NMR (300
MHz, benzene-d6): δ 5.9 (SiMe2), 27.3 (9-CMe2), 36.0 (9-CMe2),
123.8, 125.5, 130.0, 131.4, 133.0, 158.3 (aromatic carbons), 171.2,
180.6 (CO). 29Si{1H} NMR (300 MHz, benzene-d6): δ -31.7. IR
(KBr, cm-1): 1982 (br), 2008 (vs), 2038 (vs), 2100 (vs) (νCO). Mass
(EI, 70 eV) m/z 628 (M+, 23), 613 (M+- Me, 41), 600 (M+- CO,
23), 585 (M+- CO - Me, 10), 572 (M+- 2CO, 11), 557 (M+-
Attempted Reaction of 7 with Toluene-d8. Toluene-d8 (0.3 mL)
was transferred by the trap-to-trap method to an NMR tube
containing 7 (5.0 mg, 12 µmol) under high vacuum and the tube
flame-sealed. The tube was heated to 130 °C in an oil bath. The
reaction was observed periodically by measurement of the 1H NMR

5866 Organometallics, Vol. 26, No. 24, 2007
Minglana et al.
Table 3. Crystallographic Data of 2, 3, and 6
Table 2. Crystallographic Data of 1b, 4, and 3‚5
1b
4
3‚5
2
3
6
formula
fw
cryst size
(mm3)
cryst color,
habit
cryst syst
space group
a (Å)
C
27H42OSi2
C
23H24O5OsSi2
C
52H48O16Ru4Si4
formula
fw
C
23H24FeO5Si2
C
23H24O5RuSi2
C
27H32O2RuSi2
438.79
626.80
1445.54
492.46
537.68
545.79
0.20 × 0.20 × 0.20 0.35 × 0.30 × 0.10 0.30 × 0.10 × 0.10
cryst size (mm3) 0.30 × 0.25 × 0.20 0.30 × 0.30 × 0.30 0.30 × 0.30 × 0.25
cryst color
habit
cryst syst
space group
a (Å)
b (Å)
c (Å)
â (deg)
V (Å3)
Z
colorless
prismatic
monoclinic
P21/n
12.214(5)
10.05(1)
19.450(5)
92.87(3)
2385(2)
4
colorless
prismatic
monoclinic
P21/n
12.372(5)
10.10(1)
19.524(5)
93.20(3)
2436(2)
4
colorless
prismatic
monoclinic
P21/n
9.565(8)
14.535(9)
18.479(6)
92.26(4)
2567(2)
4
colorless
prismatic
monoclinic
P21
10.319(4)
10.579(3)
13.042(3)
colorless
block
monoclinic
P21/n
12.3110(7)
10.0336(6)
19.1542(19)
red
block
triclinic
P1h
15.2588(9)
17.104(1)
12.2358(6)
90.324(2)
111.541(2)
103.163(3)
2878.2(3)
2
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
97.83(2)
93.018(4)
F000
1024
0.763
1096
0.772
1128
0.725
1410.5(8)
2
2362.7(3)
4
µ (Mo KR)
(mm-1
)
F000
480
0.140
1224
5.530
1440
1.178
full matrix
F
F
F
least-square
µ (Mo KR)
(mm-1
)
reflns collected 6071
independent 5807 (0.079)
reflns (Rint
6188
5920 (0.035)
6507
6150 (0.025)
full matrix
least-square
F2
F2
F2
)
reflns collected 3603
independent 3420 (0.0281)
18006
5019 (0.0282)
25453
12542 (0.0384)
no. data used
([I > 3 σ (I)]
no. variables
R, Rw
2026
3112
3672
reflns (Rint
abs corr
)
280
280
289
0.0380, 0.0651
0.696
empirical
numerical
0.25 and 0.61
numerical
0.72 and 0.89
0.0494, 0.0786
0.74
0.0409, 0.0558
0.925
max and
0.57 and 1.00
GOF
minimum
transmission
no. variables
R1, wR2
largest difference 0.36 and -0.24
0.43 and -0.51
0. 59 and -0.34
peak and
353
0.1032, 0.1597
286
0.0356, 0.1056
697
hole (eÅ-3
)
0.0389, 0.0947
(all data)
located on the idealized positions. Selected crystallographic data
are listed in Table 2.
R1, wR2
[I > 2 σ (I)]
GOF
0.0542, 0.1355
0.0290, 0.0830
1.182
0.0314, 0.0898
1.041
1.01
X-ray Structure Determination of 2, 3, and 6. Crystals of 2,
3, and 6 were mounted at the end of a glass fiver for analysis using
a Rigaku AFC-6S diffractometer with graphite monochromated Mo
KR radiation. Data were collected at room temperature, using the
ω-2θ scan technique to maximum 2θ value of 55.0°. The data were
corrected for Lorentz and polarization effects. The structure was
solved by direct methods and expanded using Fourier techniques.
Non-hydrogen atoms were refined anisotropically. Hydrogen atoms
were included but not refined. Selected crystallographic data are
listed in Table 3.
largest difference 0.29 and -0.28
1.152 and -2.494 0.861 and -0.743
peak and hole
(eÅ-3
)
spectra. No change was observed in the spectra over 2 days of
heating.
X-ray Structure Determination of 1b, 4, and 3‚5. Crystals of
1b, 4, and 3‚5 were mounted at the end of a glass fiber for analy-
sis using a Rigaku RAXIS-RAPID imaging plate diffractometer
with graphite monochromated Mo KR radiation. Data were col-
lected at 150 K to a maximum 2θ value of 55.0°. Empirical or
numerical absorption correction was applied, and the data were
corrected for Lorentz and polarization effects. The structure was
solved by direct methods and refined by full matrix least-squares
techniques on all F2 data (SHELXL-97). The non-hydrogen atoms
were refined anisotropically, and hydrogen atoms on the silicon
atoms in 1b were refined isotropically. Other hydrogen atoms were
Supporting Information Available: CIF files giving X-ray
crystallographic data for 1b, 2, 3, 4, 3‚5, and 6. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM700720S