Me2Si(η5-C5H4) 2-bridged dinuclear ruthenium complexes: X-ray crystal structures of compounds 4a and 10b (see abstract)

Article abstract of DOI:10.1021/om980547a

The treatment of the binuclear tetracarbonyl complex [Ru₂{μ-(η⁵-C₅H₄) ₂SiMe₂}(μ-CO)₂-(CO)_a] (1) with HBF4 in dichloromethane leads to the electrophilic addition of one proton to yield the bridging hydride complex [Ru₂{μ-(η₅-C₅H₄) ₂SiMe₂}(μ-H)(CO)₄][BF₄] (2). Complex 1 also reacts with Li[BHEt₃] to afford the bridging methylene complex [Ru₂{μ-(η⁵H₄)₂SiMe ₂}-(μ-CH₂)(μ-CO)(CO)₂] (3). Binuclear complexes [Ru₂{μ-(η⁵C₅H₄) ₂SiMe₂}(X)₂X(CO)₄] (X = Cl (4a), Br (4b), and I (4c)) have been synthesized in good yields from the reaction of complex 1 with N-chlorosuccinimide (X = Cl) and X₂ (X = Br, I) in CH₂CI₂. The structure of complex 4a which has been determined by X-ray crystallography shows a three-legged piano-stool geometry around each ruthenium atom linked by the bridging Me₂Si(η⁵-C₅H₄)₂ group. The cyclopentadienyl rings which are coordinated in a η⁵ fashion are rotated in opposite directions around the Si-C(bridgehead) bond, leading to the trans arrrangement of the metal fragments and giving rise to a long ruthenium-ruthenium distance (6.120(6) A?). Complex 4c has been used as a precursor in a series of halide and carbonyl substitution reactions. The reaction of 4c with the cuprate derivative Li[CuMe₂] in THF leads to the exchange of both iodide anions to give the dimethyl complex [Ru₂(μ-(η⁵-C₅H₄) ₂SiMe₂}(CH₃)₂(CO)₄] (5). The treatment of complex 4c with AgBF₄ in refluxing acetonitrile leads to halide abstraction to afford the cationic complex [Ru₂{μ-(η⁵-C₅H₄) ₂SiMe₂}(CO)₄(NCMe)₂][BF ₄]₂ (9). The analogous reaction of complexes 4a-c with AgBF₄ in CH₂Cl₂ or acetone at room temperature gives the cationic double-bridged derivatives [Ru₂{μ-(η⁵-C₅H₄) ₂SiMe₂)}(μ-X)(CO)₄][BF₄] (10a-c). The X-ray crystal structure of 10b shows the two ruthenium moieties bridged by a halogen atom, forcing a cisoid arrangement in the molecule. Irradiation of a solution of 4c and PCy₃ in THF leads to carbonyl substitutions to yield the monocarbonyl complex [Ru₂{μ-(η⁵-C₅H₄) ₂SiMe₂}-(I)₂(CO)₂(PCy ₃)₂] (6c). Analogous isocyanide carbonyl substituted complexes [Ru₂{μ-(η⁵-C₅H₄) ₂-SiMe₂}(I)₂(CNR)_x(CO) _4-x] (R = CH₂Ph, x = 1 (7a), x = 2 (7b), x = 3 (7c), x = 4 (7d); R = Cy, x = 1 (8a), x = 2 (8b), x = 3 (8c), x = 4 (8d)) have been obtained by UV irradiation of 4c and the corresponding isocyanide in THF, depending on the ligand:complex ratio.

Full text of DOI:10.1021/om980547a

3008
Organometallics 1999, 18, 3008-3015
Me2Si(η5-C5H4)2-Br id ged Din u clea r Ru th en iu m
Com p lexes: X-r a y Cr ysta l Str u ctu r es of
[Ru 2{µ-(η5-C5H4)2SiMe2}(Cl)2(CO)4] a n d
[Ru 2{µ-(η5-C5H4)2SiMe2}(µ-Br )(CO)4][BF 4]
Richard Fro¨hlich,† J ose´ Gimeno,*,† Mercedes Gonza´lez-Cueva,† Elena Lastra,†
J avier Borge,‡ and Santiago Garc´ıa-Granda‡
Instituto Universitario de Quı´mica Organometa´lica “Enrique Moles” (Unidad Asociada al
CSIC), Departamento de Quı´mica Orga´nica e Inorga´nica, Facultad de Quı´mica, Universidad
de Oviedo, 33006 Oviedo, Spain, and Departamento de Qu´ımica Fı´sica y Analı´tica, Facultad
de Quı´mica, Universidad de Oviedo, 33006 Oviedo, Spain
Received J une 29, 1998; Revised Manuscript Received May 12, 1999
The treatment of the binuclear tetracarbonyl complex [Ru2{µ-(η5-C5H4)2SiMe2}(µ-CO)2-
(CO)2] (1) with HBF4 in dichloromethane leads to the electrophilic addition of one proton to
yield the bridging hydride complex [Ru2{µ-(η5-C5H4)2SiMe2}(µ-H)(CO)4][BF4] (2). Complex 1
also reacts with Li[BHEt3] to afford the bridging methylene complex [Ru2{µ-(η5-C5H4)2SiMe2}-
(µ-CH2)(µ-CO)(CO)2] (3). Binuclear complexes [Ru2{µ-(η5-C5H4)2SiMe2}(X)2(CO)4] (X ) Cl (4a ),
Br (4b), and I (4c)) have been synthesized in good yields from the reaction of complex 1
with N-chlorosuccinimide (X ) Cl) and X2 (X ) Br, I) in CH2Cl2. The structure of complex
4a which has been determined by X-ray crystallography shows a three-legged piano-stool
geometry around each ruthenium atom linked by the bridging Me2Si(η5-C5H4)2 group. The
cyclopentadienyl rings which are coordinated in a η5 fashion are rotated in opposite directions
around the Si-C(bridgehead) bond, leading to the trans arrrangement of the metal fragments
and giving rise to a long ruthenium-ruthenium distance (6.120(6) Å). Complex 4c has been
used as a precursor in a series of halide and carbonyl substitution reactions. The reaction
of 4c with the cuprate derivative Li[CuMe2] in THF leads to the exchange of both iodide
anions to give the dimethyl complex [Ru2(µ-(η5-C5H4)2SiMe2}(CH3)2(CO)4] (5). The treatment
of complex 4c with AgBF4 in refluxing acetonitrile leads to halide abstraction to afford the
cationic complex [Ru2{µ-(η5-C5H4)2SiMe2}(CO)4(NCMe)2][BF4]2 (9). The analogous reaction
of complexes 4a -c with AgBF4 in CH2Cl2 or acetone at room temperature gives the cationic
double-bridged derivatives [Ru2{µ-(η5-C5H4)2SiMe2)}(µ-X)(CO)4][BF4] (10a -c). The X-ray
crystal structure of 10b shows the two ruthenium moieties bridged by a halogen atom, forcing
a cisoid arrangement in the molecule. Irradiation of a solution of 4c and PCy3 in THF leads
to carbonyl substitutions to yield the monocarbonyl complex [Ru2{µ-(η5-C5H4)2SiMe2}-
(I)2(CO)2(PCy3)2] (6c). Analogous isocyanide carbonyl substituted complexes [Ru2{µ-(η5-C5H4)2-
SiMe2}(I)2(CNR)x(CO)4-x] (R ) CH2Ph, x ) 1 (7a ), x ) 2 (7b), x ) 3 (7c), x ) 4 (7d ); R ) Cy,
x ) 1 (8a ), x ) 2 (8b), x ) 3 (8c), x ) 4 (8d )) have been obtained by UV irradiation of 4c and
the corresponding isocyanide in THF, depending on the ligand:complex ratio.
In tr od u ction
Due to the free rotation around the two silicon-
cyclopentadienyl bonds, a number of different conforma-
tions may be adopted by a dimetallic fragment of the
The bridged bis(cyclopentadienyl) systems [X(C5H4)2]2-
(X ) CH2, SiMe2, SnMe2, GeMe2, etc.) have been shown
to be appropriate ligands in the formation of dinuclear
compounds which are resistant to fragmentation. These
derivatives are especially attractive for studying the
potential interactions between two reactive sites, since
the presence of the bridge places the two metal atoms
in close proximity. Most of the [X(C5H4)2] (X ) CH2,
SiMe2) bridged metal complexes belong to groups 4,1 6,2
and 9 (Rh and Ir),3 but to the best of our knowledge
only a few examples are known for group 8 metals.4
(1) (a) Cuenca, T.; Flores, J . C.; Gomez, R.; Gomez Sal, P.; Parra-
Hake, M.; Royo, P. Inorg. Chem. 1993, 32, 3608. (b) Cuenca, T.; Padilla,
A.; Royo, P.; Parra-Hake, M.; Pellinghelli, M. A.; Tiripicchio, A.
Organometallics 1995, 14, 848. (c) Reddy, K. P.; Petersen, J . L.
Organometallics 1989, 8, 2107. (d) Reddy, K. P.; Petersen, J . L.
Organometallics 1989, 8, 547. (e) Cacciola, J .; Reddy, K. P.; Petersen,
J . L. Organometallics 1992, 11, 665. (f) Ciruelo, G.; Cuenca, T.; Gomez
Sal, P.; Martin, A.; Royo, P. J . Chem. Soc., Dalton Trans 1995, 21,
231.
(2) (a) Gomez Sal, P.; De J esus, E.; Perez, A. I.; Royo, P. Organo-
metallics 1993, 12, 4633. (b) Heck, J .; Kriebisch, K.; Mellinghoff, H.
Chem. Ber. 1988, 121, 1753. (c) Abriel, W.; Heck, J . J . Organomet.
Chem. 1986, 302, 363. (d) Bitterwolf, T. E.; Rheingold, A. L. Organo-
metallics 1991, 10, 3856. (e) Bitterwolf, T. E.; Rheingold, A. L.; Fierro,
R.; Yap G. P. A.; Liable-Sands, L. M. J . Organomet. Chem. 1996, 524,
19. (f) Amor, F.; Gomez Sal, P.; De J esus, E.; Martin, A.; Perez, A. I.;
Royo, P.; De Miguel, A. Organometallics 1996, 15, 2103.
* Author to whom correspondence should be addressed. E-mail:
jgh@sauron.quimica.uniovi.es.
† Departamento de Qu´ımica Orga´nica e Inorga´nica.
‡ Departamento de Qu´ımica F´ısica y Anal´ıtica.
10.1021/om980547a CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/10/1999

Me2Si(η5-C5H4)2-Bridged Dinuclear Ru Complexes
Organometallics, Vol. 18, No. 16, 1999 3009
Ch a r t 1
SiMe2}(CO)2(µ-CO)2] (1). Herein we report the synthesis
of novel derivatives (Scheme 1): (i) [Ru2{µ-(η5-C5H4)2-
SiMe2}(µ-H)(CO)4][BF4] (2) and [Ru2{µ-(η5-C5H4)2SiMe2}-
(µ-CH2)(µ-CO)(CO)2] (3), in which the metal atoms are
also linked by a metal-metal bond; (ii) carbonyl com-
plexes [Ru2{µ-(η5-C5H4)2SiMe2}(X)2(CO)4] (X ) Cl (4a );
X ) Br (4b); X ) I (4c); X ) Me (5)); (iii) carbonyl
substituted derivatives [Ru2{µ-(η5-C5H4)2SiMe2}(I)2(L)x-
(CO)4-x] (L ) PCy3, x ) 2 (6c); L ) CNCH2Ph, x ) 1
(7a ), x ) 2 (7b), x ) 3 (7c), x ) 4 (7d ); L ) CNCy, x )
1 (8a ), x ) 2 (8b), x ) 3 (8c), x ) 4 (8d )); (iv) cationic
complexes [Ru2{µ-(η5-C5H4)2SiMe2}(CO)4(NCMe)2][BF4]2
(9) and [Ru2{µ-(η5-C5H4)2SiMe2}(µ-X)(CO)4][BF4] (10a -
c). The synthetic approaches of the novel compounds
(Scheme 1) show the robustness of the bridging system
which remains unchanged through all the transforma-
tions leading to a variety of dinuclear ruthenium(II)
complexes.
type [M2{µ-(η5-C5H4)2SiMe2}]. To date, three structural
types (Chart 1) have been observed and crystallographi-
cally characterized for transition metals: (a) type A, in
which the metal fragments are coordinated in an exo
disposition with respect to the rings of the bridging
group and are located in a mutually cis orientation
giving rise to a formally exo-cis dimetallic arrange-
ment;1c,2a (b) type B, in which the metal fragments are
coordinated in an endo fashion with respect to the rings
and in a mutually cis orientation (endo-cis dimetallic
arrangement);1b-f,2c-f,4a-d and (c) type C, which results
from the rotation in type A or B of one of the (η5-C5H4)M
fragments around the corresponding Si-C bond leading
to a formally trans dimetallic arrangement.1a In com-
plexes of type B the metals atoms may also be linked
either by an additional bridging ligand or by a metal-
metal bond,2d which prevents the two metallic frag-
ments from being located far away from each other, as
in types A and C.
During the past few years we have described a large
series of alkynyl, vinylidene, and allenylidene complexes
using the half-sandwich moiety “M(η5-ring)L2” (M ) Fe,
ring ) C5H5; M ) Ru, Os, ring ) C9H7, C9MexH7-x) as
metal fragments.5 With the aim of extending this
chemistry to dinuclear derivatives and in order to
provide suitable precursors we have explored the syn-
thesis of Me2Si(η5-C5H4)2 bridged ruthenium derivatives
from the known4d,6 dinuclear complex [Ru2{µ-(η5-C5H4)2-
Exp er im en ta l Section
Gen er a l Com m en ts. The reactions were carried out under
dry nitrogen using Schlenk techniques. All solvents were dried
by standard methods and distilled under nitrogen before use.
Methyl isobutyl ketone, I2, Br2, N-chlorosuccinimide, Na2S2O3,
anhydrous MgSO4, CuI, MeLi, AgBF4, HBF4‚OEt2, Li[BHEt3],
benzyl isocyanide, and cyclohexyl isocyanide were used as
1c
received from Aldrich Chemical Co. Me2Si(C5H5)2 and [Ru2-
{µ-(η5-C5H4)2SiMe2}(µ-CO)2(CO)2]4d were synthesized by a
modified published method.
Photolysis experiments were performed with external ir-
radiation using a UV lamp (400 W, Applied Photophysics).
Infrared spectra were recorded on a Perkin-Elmer 1720-XFT
spectrometer. The conductivities were measured at room
temperature, in ca. 10-3 mol dm-3 acetone solutions, with a
J enway PCM3 conductimeter. The C, H, and N analyses were
carried out with a Perkin-Elmer 2400 microanalyzer. Unsat-
isfactory analyses were obtained for complex 5 (oil) and
isocyanide complexes 7a -d and 8a -d (obtained in rather low
yields). All of them have been fully characterized by IR and
NMR spectroscopy (See Supporting Information). The NMR
spectra were recorded on a Bruker AC300 instrument at 300
(1H), 121.5 (31P), or 75.4 MHz (13C) and on an AC200 instru-
ment at 200 (1H), 81.0 (31P), or 50.3 MHz (13C) using SiMe4 or
85% H3PO4 as standards.
Syn t h esis of [Me2Si(C5H 5)2]. LinBu (1.6 M solution in
hexane) (43.75 mL, 70 mmol) was added dropwise to a solution
of C5H6 (9 mL, 108.8 mmol) in THF at -60 °C. This mixture
was stirred for 2 h, and freshly distilled SiCl2Me2 (3.9 mL, 32
mmol) was added. The temperature was allowed to reach room
temperature during 2 h and stirred for an additional 1 h. The
solvents were then removed in vacuo, and the product was
extracted with pentane. Evaporation of the solvent in the
resulting yellow solution afforded the ligand as an orange oil
(5.4 mL, 89% yield).
(3) (a) Bitterwolf, T. E. J . Organomet. Chem. 1987, 320, 121. (b)
Bitterwolf, T. E.; Rheingold, A. L. Organometallics 1987, 6, 2138. (c)
Bitterwolf, T. E.; Gambaro, A.; Gottardi, F.; Valle, G. Organometallics
1991, 10, 1416.
(4) (a) Weaver, J .; Woodward, P. J . Chem. Soc., Dalton Trans 1973,
1439. (b) Wright, M. E.; Mezza T. M.; Nelson G. O.; Armstrong N. R.
Organometallics 1983, 2, 1711. (c) Knox, S. A. R.; MacPherson, K. A.;
Guy Orpen, A.; Rendle, M. C. J . Chem. Soc., Dalton Trans. 1989, 1807.
(d) Bitterwolf, T. E.; Leonard, M. B.; Horine, P. A.; Shade, J . E.;
Rheingold, A. L.; Staley, D. J .; Yap, G. P. A. J . Organomet. Chem. 1996,
512, 11. (e) Bitterwolf, T. E.; Shade, J . E.; Hansen, J . A.; Rheingold,
A. L. J . Organomet. Chem. 1996, 514, 13.
(5) Fe: (a) Gamasa, M. P.; Gimeno, J .; Lastra, E.; Martin-Vaca, B.
M.; Organometallics 1992, 11, 373. Ru: (b) Gamasa, M. P.; Gimeno,
J .; Gonza´lez-Bernardo, C.; Borge, J .; Garc´ıa-Granda, S. Organometal-
lics 1997, 16, 2483. (c) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Lo´pez-
Gonza´lez, M. C.; Borge, J .; Garc´ıa-Granda, S. Organometallics 1997,
16, 4453. (d) Gamasa, M. P.; Gimeno, J .; Mart´ın-Vaca, B. M. Organo-
metallics 1998, 17, 3707. Os: (e) Gamasa, M. P.; Gimeno, J .; Gonzalez-
Cueva, M.; Lastra, E. J . Chem. Soc., Dalton Trans. 1996, 2547. (f)
Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonzalez-Cueva, M.; Lastra,
E.; Borge, J .; Garcia-Granda, S.; Perez-Carren˜o, E. Organometallics
1996, 15, 2137.
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(µ-CO)2(CO)2] (1).
A mixture of [Ru3(CO)12] (4.44 g, 6.94 mmol) and Me2Si(C5H5)2
(1.98 mL, 10.41 mmol) in methyl isobutyl ketone (300 mL) was
heated under reflux for 90 min. The solution was then
concentrated under reduced pressure to give complex 1 (5.20
g, 83%) as a yellow solid. Spectroscopic data (1H NMR and
IR) are in accord with the previously reported data.4d
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(µ-H)(CO)4][BF 4]
(2). HBF4‚OEt2 (0.03 mL, 0.2 mmol) was added to a solution
of complex 1 (0.10 g, 0.2 mmol) in dicholoromethane (5 mL).
The resulting mixture was stirred for 15 min and the solvent
removed in vacuo. The solid was washed with diethyl ether (2
× 10 mL) and vacuum-dried to give complex 2 (0.08 g, 63%)
as a yellow, air-unstable solid. νmax/cm-1 (CH2Cl2) 2075, 2048,
2021. NMR data: see Tables 1 and 2.
(6) The X-ray structure of complex 1 was first reported by Bitterwolf
(ref 4d). A further crystal structure determination was later reported:
Zhou, X.; Zhang, Y.; Xu, S.; Tian, G.; Wong, B. Inorg. Chim. Acta 1997,
262, 109.

3010 Organometallics, Vol. 18, No. 16, 1999
Frohlich et al.
Sch em e 1a
a
(i) +HBF4 (CH2Cl2, rt, 15 min), (ii) acetone, rt, (iii) +Li[BHEt3] (toluene, rt, 15 min), (iv) +X2 (CH2Cl2, rt, 30 min, X ) I, Br)
or +N-chlorosuccinimide (CH2Cl2, rt, 30 min, X ) Cl), (v) +Li[CuMe2] (thf, rt, 15 min), (vi) +PCy3 (thf, hν, -20 °C, 9 h), (vii) +
AgBF4 (refluxing NCMe, 6 h), (viii) +AgBF4 (CH2Cl2 (10a ) or acetone (10b,c), rt, 30 min).
Ta ble 1. 1H NMR Da ta a
{µ-(η5-C5H4)2SiMe2}
Me
0.58
Cp
J HH
others
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-H)(CO)4][BF4] (2)
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-CH2)(CO)3] (3)
5.76 (m), 6.00 (m)
5.07 (m), 5.30 (m), 5.80 (m),
5.86 (m)
5.44 (t), 5.61 (t)
5.45 (t), 5.61 (t)
5.51 (t), 5.65 (t)
4.62 (t), 4.77 (t)
4.72 (m), 5.13 (m), 5.15 (m),
5.20 (m), 5.67 (m), 5.74 (m)
6.01 (t), 6.35 (t)
-18.71 (H)
7.00, 8.94 (d, CH2,
J HH ) 1.5 Hz)
0.39, 0.50
[Ru2{µ-(η5-C5H4)2SiMe2(Cl)2(CO)4] (4a )
[Ru2{µ-(η5-C5H4)2SiMe2}(Br)2(CO)4] (4b)
[Ru2{µ-(η5-C5H4)2SiMe2}(I)2(CO)4] (4c)
[Ru2{µ-(η5-C5H4)2SiMe2}(CH3)2(CO)4]b (5)
[Ru2{µ-(η5-C5H4)2SiMe2}(I)2(CO)2(PCy3)2]c (6c)
0.63
0.64
0.64
0.49
0.71
1.9
1.9
1.9
2.2
0.24 (Me)
1.25, 1.83, 2.16 (m, PCy3)
d
[Ru2{µ-(η5-C5H4)2SiMe2}(CO)4(NCMe)2][BF4]2 (9)
0.75
0.69
0.67
0.63
1.9
1.7
2.0
1.8
2.61 (s, NCMe)
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-Cl)(CO)4][BF4] (10a )
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-Br)(CO)4][BF4] (10b)
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-I)(CO)4][BF4] (10c)
5.38 (t), 6.07 (t)
5.45 (t), 6.06 (t)
5.62 (t), 6.07 (t)
a
b
d
δ in parts per million and J in hertz. Spectra recorded in CDCl3. Spectra recorded in C6D6. c Two isomers. Spectra recorded in
CD3COCD3.
Syn t h esis of [R u 2{µ-(η5-C5H 4)2SiMe2}(µ-CH 2)(µ-CO)-
imide (0.14 g, 1 mmol) in dichloromethane (70 mL) was stirred
for 30 min. The solution was then concentrated at reduced
pressure, and diethyl ether was added to give complex 4a (0.22
(CO)2] (3). Li[BHEt3] (4.80 mL, 4.8 mmol) was added to a
solution of complex 1 (0.50 g, 1 mmol) in toluene (48 mL). The
resulting mixture was stirred for 15 min and the solvent
removed in vacuo. Chromatography on silica, with hexane-
dichloromethane (4:1) as eluent, afforded a yellow band, which
after evaporation gave the complex 3 (0.11 g, 22%) as a yellow
solid. Found: C, 39.5; H, 3.3. C16H16O3Ru2Si requires C, 39.5;
H, 3.3. νmax/cm-1 (CH2Cl2): 1982, 1944, 1784. νmax/cm-1 (KBr):
1959, 1923, 1900, 1795 (CO), 1255, 1162, 1056, 886, 824, 673
(Cp2SiMe2).
g, 75%) as a yellow solid. νmax/cm-1 (CH2Cl2): 2054, 2002. νmax
cm-1 (KBr): 2047,1989 (CO), 1250, 1167, 1064, 892, 837, 671
(Cp2SiMe2).
/
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(Br )2(CO)4] (4b). A
solution of Br2 (0.4 mmol) in dichloromethane (0.4 mL) was
added to a solution of complex 1 (0.20 g, 0.4 mmol) in
dichloromethane (35 mL). After stirring for 30 min, the
resulting mixture was washed with a saturated solution of
Na2S2O3 in water, the organic layer was dried with anhydrous
MgSO4 and filtered, and the solvent was removed in vacuo.
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(Cl)2(CO)4] (4a ). A
mixture of complex 1 (0.25 g, 0.5 mmol) and N-chlorosuccin-

Me2Si(η5-C5H4)2-Bridged Dinuclear Ru Complexes
Organometallics, Vol. 18, No. 16, 1999 3011
Ta ble 2. 13C{1H} NMR Da ta a
{µ-(η5-C5H4)2SiMe2}
c
Me
-2.4
Cp
Cpq
89.1
CO
others
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-H)(CO)4][BF4] (2)
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-CH2)(CO)3] (3)
[Ru2{µ-(η5-C5H4)2SiMe2}(Cl)2(CO)4] (4a )
[Ru2{µ-(η5-C5H4)2SiMe2}(Br)2(CO)4] (4b)
[Ru2{µ-(η5-C5H4)2SiMe2}(I)2(CO)4] (4c)
[Ru2{µ-(η5-C5H4)2SiMe2}(CH3)2(CO)4] (5)
[Ru2{µ-(η5-C5H4)2SiMe2}(I)2(CO)2(PCy3)2]b (6)
91.6, 92.2
195.6
201.3
196.8
196.4
196.1
202.6
-2.1, -1.6 87.6, 89.9, 98.2, 100.7 83.0
105.1 (CH2)
-0.9
-0.6
-0.4
-0.4
86.4, 100.2
86.9, 99.7
87.7, 98.3
90.7, 97.2
88.9
88.1
91.2
-32.1(Me)
-0.4, 0.1 84.2-86.2, 106.4
0.7, 1.1
-2.2
97.8, 98.1 206.8 (d), J CP ) 19.7 Hz 26.8-39.3 (Cy)
206.5 (d), J CP ) 19.7 Hz
[Ru2{µ-(η5-C5H4)2SiMe2}(CO)4(NCMe)2]-
[BF4]2 (9)
87.6, 99.8
87.0
192.8
4.1 (NCMe),
131.8 (NCMe)
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-Cl)(CO)4][BF4] (10a ) -3.0
83.9, 99.8
84.7, 99.7
86.4, 99.3
105.8
99.9
97.3
194.4
194.2
194.5
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-Br)(CO)4][BF4] (10b) -2.7
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-I)(CO)4][BF4](10c)
-2.2
a
b
δ in ppm. Spectra recorded in CD2Cl2. Two isomers. c Quaternary carbon of the cyclopentadienyl rings.
The residue was then dissolved in diethyl ether, and hexane
was added to give complex 4b (0.21 g, 77%) as a yellow solid.
Found: C, 29.3; H, 2.2. C16H14Br2O4Ru2Si requires C, 29.1; H,
2.1. νmax/cm-1 (CH2Cl2): 2052, 2003. νmax/cm-1 (KBr): 2045,
2011, 1985 (CO), 1254, 1164, 1056, 891, 836, 674 (Cp2SiMe2).
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(I)2(CO)4] (4c). A
solution of I2 (0.61 g, 2.4 mmol) in dichloromethane (30 mL)
was added to a solution of complex 1 (1.20 g, 2.4 mmol) in
dichloromethane (60 mL), and the resulting mixture was
stirred for 30 min. The solution was then concentrated at
reduced pressure, and hexane was added to give complex 4c
(1.79 g, 99%) as a yellow solid. Found: C, 25.5; H, 1.9.
(s, br, 2H, C5H4), 5.30 (s, br, 2H, C5H4), 5.20 (s, br, 4H, C5H4),
5.00 (s, 4H, CH2), 0.46 (virtual triplet J HH ) 3.0 Hz, 6H, CH3).
13C{1H} NMR (CD2Cl2/CH2Cl2) (δ, ppm): 200.5 (CO), 147.2
(CN), 133.4, 129.4, 128.9, 127.1 (Ph), 96.3, 94.9, 85.5, 84.1
(C5H4), 49.0 (CH2), -0.1 (CH3). 7c: eluent 1:4 hexane-CH2Cl2.
Yield: 0.02 g, 6.5%. νmax/cm-1 (CH2Cl2) 2160, 2119 (CN), 1980
(CO). 1H NMR (CDCl3) (δ, ppm): 7.51-7.20 (m, 15H, Ph), 5.30
(m, 6H, C5H4), 5.16 (m, 1H, C5H4), 5.09 (m, 1H, C5H4), 4.96
(m, 6H, CH2), 0.41 (s, 6H, CH3). (The 1H NMR spectra are
provided as Supporting Information for complexes 7a -c.)
Syn t h esis of [R u 2{µ-(η5-C5H4)2SiMe2}(I)2(CNCH2P h )4]
(7d ). A mixture of complex 4c (0.25 g, 0.3 mmol) and benzyl
isocyanide (0.37 mL, 3 mmol) in THF (60 mL) was irradiated
with a UV lamp at 0 °C for 6.5 h and the solvent removed in
vacuo. Chromatography on silica at 0 °C, with hexane-CH2Cl2
(1:10) as eluent, gave a major band identified as the complex
7d (0.08 g, 24%). νmax/cm-1 (CH2Cl2): 2156, 2117 (CN). 1H NMR
(CDCl3) (δ, ppm): 7.51-7.20 (m, 20H, Ph), 5.07 (m, 8H, C5H4,
C
16H14I2O4Ru2Si requires C, 25.5; H, 1.9. νmax/cm-1 (CH2Cl2):
2048, 1999. νmax/cm-1 (KBr): 2043, 2034, 1992, 1980 (CO),
1253, 1170, 1067, 893, 834, 680 (Cp2SiMe2).
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(CH3)2(CO)4] (5).
A solution of LiMe in hexane (6.3 mL, 9.4 mmol) was added
to a solution of CuI (0.9 g, 4.7 mmol) in THF (30 mL) until the
complete dissolution of the precipitate formed initially was
achieved. The resulting solution was added to a solution of
complex 4c (1.03 g, 1.36 mmol) in THF (200 mL), and the
mixture was stirred for 15 min. After evaporation to dryness
at reduced pressure, the residue was extracted with diethyl
ether. The solvent was then removed in vacuo to give complex
1
4.93 (m, 8H, CH2), 0.37 (s, 6H, CH3). (The H NMR spectrum
is provided as Supporting Information.)
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(I)2(CNCy)x(CO)4-x],
x ) 1 (8a ), 2 (8b), 3 (8c), 4 (8d ). A mixture of complex 4c
(0.15 g, 0.2 mmol) and cyclohexyl isocyanide (0.05 mL, 0.4
mmol) in THF (50 mL) was irradiated with a UV lamp for 3 h
at -20 °C and the solvent removed in vacuo. Chromatography
on silica, with hexane-dichloromethane as eluent, permits the
separation of five bands from which, after removal of the
solvents, complexes 8a -d were isolated as follows. Unreacted
starting material was recovered using hexane as eluent. Using
as eluent a 10:3 mixture of hexane-CH2Cl2, a yellow band was
collected, from which complex 8a was obtained. With a 2:1
hexane-CH2Cl2 ratio a yellow band was obtained, from which
a yellow solid identified as complex 8b was isolated. A solvent
ratio of 1:5 leads to the separation of a fourth band, from which
complex 8c was isolated, and a final band was collected using
dichloromethane as solvent (complex 8d ). 8a : eluent hexane-
CH2Cl2 (10:3). νmax/cm-1 (CH2Cl2): 2168 (CN), 2046, 1996, 1979
5 (0.59, 82%) as a brown oil. νmax/cm-1 (THF): 2012, 1951. νmax
/
cm-1 (KBr): 2962, 2904, 2819, (CH3), 2015, 1941 (CO), 1260,
1
1163, 1060, 891, 829, 674 (Cp2SiMe2). (The H NMR spectrum
is provided as Supporting Information.)
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(I)2(CO)2(P Cy3)2]
(6c). A mixture of complex 4c (0.30 g, 0.4 mmol) and PCy3
(0.34 g, 1.2 mmol) in THF (60 mL) was irradiated with a UV
lamp at -20 °C for 9 h and the solvent removed in vacuo.
Chromatography on silica, with hexane-dichloromethane (3:
1) as eluent, gave the complex 6c (0.26 g, 50%) as a yellow
solid. Found: C, 47.5; H, 6.5. C50H44I2O2P2Ru2Si requires C,
47.7; H, 6.4. νmax/cm-1 (CH2Cl2): 1942. νmax/cm-1 (KBr): 2964,
2920, 2851, (CH2), 1938 (CO), 1262, 1175, 881, 844, 684
(Cp2SiMe2). 31P{1H} (δ, ppm): 57.0, 57.1.
1
(CO). H NMR (CDCl3) (δ, ppm): 5.64 (m, 1H, C5H4), 5.61 (m,
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(I)2(CNCH2P h )x-
(CO)4-x], x ) 1 (7a ), 2 (7b), 3 (7c). A mixture of complex 4c
(0.25 g, 0.3 mmol) and benzyl isocyanide (0.10 mL, 0.8 mmol)
in THF (60 mL) was irradiated with a UV lamp at -20 °C for
5 h and the solvent removed in vacuo. Chromatography on
silica at 0 °C, with hexane-dichloromethane as eluent, gave
different yellow bands, from which the complexes 7a -c were
isolated after removing the solvents. 7a : eluent 3:4 hexane-
CH2Cl2. Yield: 0.01 g, 4%. νmax/cm-1 (CH2Cl2): 2172 (CN),
2046, 1996, 1984 (sh) (CO). 1H NMR (CDCl3) (δ, ppm): 7.42
(m, 5H, Ph), 5.61 (m, 2H, C5H4), 5.46 (m, 3H, C5H4), 5.33 (m,
1H, C5H4), 5.27 (m, 2H, C5H4), 5.03 (s, 2H, CH2), 0.56 (s, 3H,
CH3), 0.54 (s, 3H, CH3). 7b: eluent 1:2 hexane-CH2Cl2.
Yield: 0.028 g, 10.3%. νmax/cm-1 (CH2Cl2): 2171 (CN), 1982
(CO). 1H NMR (CDCl3) (δ,ppm): 7.46-7.32 (m, 10H, Ph), 5.37
1H, C5H4), 5.49 (m, 2H, C5H4), 5.41 (m, 1H, C5H4), 5.29 (m,
1H, C5H4), 5.22 (m, 2H, C5H4), 3.97 (m, 1H, CH), 1.93-1.65
(m, 6H, CH2), 1.52-1.30 (m, 4H, CH2), 0.88 (s, 3H, CH3), 0.85
(s, 3H, CH3). 8b: eluent hexane-CH2Cl2 (2:1). νmax/cm-1
(CH2Cl2): 2167 (CN), 1978 (CO). 1H NMR (CDCl3) (δ, ppm)
5.37 (s, br, 2H, C5H4), 5.29 (s, br, 2H, C5H4), 5.21 (m, 4H, C5H4),
3.97 (m, 2H, CH), 2.00-1.65 (m, 11H, CH2), 1.60-1.30 (m, 9H,
CH2), 0.54 (s, 6H, CH3). 8c: eluent hexane-CH2Cl2 (1:5). νmax
/
cm-1 (CH2Cl2): 2153, 2114 (CN), 1976 (CO). 1H NMR (CDCl3)
(δ, ppm): 5.34 (m, 1H, C5H4), 5.32 (m, 1H, C5H4), 5.23 (m, 2H,
C5H4), 5.05 (m, 2H, C5H4), 4.95 (m, 2H, C5H4), 3.94 (m, 3H,
CH), 2.0-1.6 (m, 19H, CH2), 1.6-1.3 (m, 11H, CH2), 0.54 (s,
3H, CH3), 0.53 (s, 3H, CH3). 8d : eluent CH2Cl2. νmax/cm-1
(CH2Cl2): 2153, 2120 (CN). 1H NMR (CDCl3) (δ, ppm): 5.20
(m, 4H, C5H4), 4.89 (m, 4H, C5H4), 4.01 (m, 4H, CH), 2.0-1.6

3012 Organometallics, Vol. 18, No. 16, 1999
Frohlich et al.
(m, 20H, CH2), 1.6-1.3 (m, 20H, CH2), 0.43 (s, 6H, CH3). (The
1H NMR spectra of 8a -d are provided as Supporting Informa-
tion.)
and 1.02. A semiempirical absorption correction was applied
using ψ scans14 resulting in maximum and minimum correc-
tion factors of 1.00 and 0.58, respectively. Isotropic full-matrix
2
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(CO)4(NCMe)2]-
[BF 4]2 (9). A mixture of complex 4c (0.10 g, 0.14 mmol) and
AgBF4 (0.11 g, 0.53 mmol) in acetonitrile (10 mL) was heated
under reflux for 6 h. The solution was filtered and concentrated
at reduced pressure, and diethyl ether (2 × 10 mL) was then
added to give complex 9 (0.042 g, 42%) as a yellow solid.
Found: C, 31.6; H, 2.7; N, 3.6. C20H20B2F8N2O4Ru2Si requires
least-squares refinement on Fo converged to R ) 0.086. At
this stage an empirical absorption correction was applied using
XABS2.15 Maximum and minimum transmission factors were
1.00 and 0.52, respectively. The geometrically placed hydrogen
atoms were isotropically refined, riding on their parent atoms,
with two common thermal parameters; one for the hydrogen
atoms bonded to aromatic rings, and the other for the hydrogen
atoms bonded to the methyl groups. The function minimized
C, 31.8; H, 2.7; N, 3.7. νmax/cm-1 (NCMe): 2081, 2035. νmax
/
2
was [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2, w ) 1/[σ2(Fo2) + (0.0711P)2 +
cm-1 (KBr): 2300 (CN), 2074, 2045, 1992 (CO), 1260 (Cp2SiMe2),
1069 (BF4), 1031, 891, 836, 677 (Cp2SiMe2).
1.44P] where P ) (Max(Fo2,0) + 2Fc2)/3 with σ2(Fo2) from
counting statistics. Final R1 ) 0.0398 and Rw(F2) ) 0.1030
(both for I > 2σ(I)). The maximum shift to esd ratio in the
last full-matrix least-squares cycle was 0.005. The final
difference Fourier map showed no peaks higher than 1.04 e
Syn th esis of [Ru 2{µ-(η5-C5H4)2SiMe2}(µ-X)(CO)4][BF 4],
X ) Cl (10a ), Br (10b), I (10c). A mixture of complex 4a -c
(0.13 mmol) and AgBF4 (0.06 g, 0.26 mmol) in dichloromethane
(20 mL) (10a ) or acetone (20 mL) (10b-c) was stirred for 30
min. The solution was filtered and concentrated at reduced
pressure, and diethyl ether (2 × 10 mL) was then added to
Å-3 (near the Ru atoms), nor deeper than -0.75 e Å-3
Crystal data for 10b: [C33H30B2Br2Cl2F8O8Ru4Si2]; Mr
1419.37; orthorhombic; space group Pbca; a ) 15.7155(10) Å,
b ) 32.155(8) Å, c ) 18.6302(18) Å; V ) 9415(3) Å3; Fcalcd
.
)
give complexes 10a -c as yellow solids. 10a : yield 35%. νmax
/
cm-1 (CH2Cl2): 2075, 2064, 2025. 10b: yield 63%. Found: C,
28.7; H, 2.1. C16H14BBrF4O4Ru2Si requires C, 28.8; H, 2.1. νmax
)
2.003 g cm-3; F(000) ) 5456; µ ) 3.197 mm-1; red crystal (0.26
× 0.20 × 0.13 mm); T ) 293 K; λ(Mo KR) ) 0.710 73 Å; 8818
reflections measured. Two different molecules have been found
in the asymmetric unit as well as a dichloromethane solvent
molecule of crystallization. The unit cell parameters were
obtained from the least-squares fit of 25 reflections (with θ
between 15° and 17°). The final drift correction factors were
between 0.98 and 1.03. The geometrically placed hydrogen
atoms were isotropically refined, riding on their parent atoms,
with three common thermal parameters: the first one for the
hydrogen atoms bonded to aromatic rings, the second one for
the hydrogen atoms bonded to the methyl groups, and the third
one for those belonging to the CH2Cl2 solvent molecule. The
/
cm-1 (CH2Cl2): 2074, 2064, 2025. νmax/cm-1 (KBr): 2046, 1992
(CO), 1258, 1163, 890, 833, 675 (Cp2SiMe2), 1063 (BF4).
Conductivity (acetone, 20 °C, Ω-1 cm2 mol-1): 129.6. 10c: yield
82%. νmax/cm-1 (CH2Cl2): 2070, 2059, 2022; νmax/cm-1 (KBr)
2046, 1996 (CO), 1264, 1163, 885, 836, 678 (Cp2SiMe2), 1059
(BF4). Conductivity (acetone, 20 °C, Ω-1 cm2 mol-1): 129.9.
X-r a y Diffr a ction Stu d ies of 4a a n d 10b. Crystals
suitable for X-ray diffraction analyses were obtained by slow
diffusion of hexane (4a ) or diethyl ether (10b) into a concen-
trated solution of the complexes in dichloromethane. Both
diffraction measurements were made on an Enraf-Nonius
CAD4 diffractometer. Data were collected with the ω-2θ scan
technique and a variable scan rate, with a maximum scan time
of 60 s per reflection. On all reflections, profile analysis7,8 was
performed. Lorentz and polarization corrections were applied,
function minimized was [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2, w )
2
1/[σ2(Fo2) + (0.0563P)2 + 28.27P] where P ) (Max(Fo2,0) +
2Fc2)/3 with σ2(Fo2) from counting statistics. Final R1 ) 0.0473
and Rw(F2) ) 0.1095 (both for I > 2σ(I)). The maximum shift
to esd ratio in the last full-matrix least-squares cycle was
0.013. The final difference Fourier map showed no peaks
higher than 1.86 e Å-3 (near the Ru atoms), nor deeper than
2
and the data were reduced to Fo values. The structures were
solved by DIRDIF-969 (Patterson methods and phase expan-
2
sion). Full-matrix least-squares refinement on Fo using
SHELXL9710 was performed. All hydrogen atoms were geo-
metrically placed. During the final stages of the refinement,
the positional parameters and the anisotropic thermal param-
eters of the non-H atoms were refined. Atomic scattering
factors were taken from International Tables for X-Ray
Crystallography (1974).11 Geometrical calculations were made
with PARST97.12 The crystallographic plots were made with
EUCLID.13 All calculations were made at the University of
Oviedo on the X-Ray group ALPHA-AXP computers.
-0.85 e Å-3
.
Resu lts a n d Discu ssion
Rea ctivity of Com p lex [Ru 2{µ-(η5-C5H4)2SiMe2}-
(µ-CO)2(CO)2] (1). The starting material is the complex
[Ru2{µ-(η5-C5H4)2SiMe2}(µ-CO)2(CO)2] (1) which has
been synthesized (83% yield) by heating under reflux a
solution of [Ru3(CO)12] and Me2Si(C5H5)2 in methyl
isobutyl ketone. This complex, which has been previ-
ously prepared in much lower yield (8%),4d proves to be
a good precursor for the synthesis of a variety of
dinuclear derivatives (Scheme 1).
Treatment of a solution of 1 in dichloromethane with
a stoichiometric amount of HBF4‚OEt2 proceeds rapidly
with electrophilic addition of one proton to yield the
hydride complex 2 (63% yield). No evidence has been
found for C-Si bond cleavage. Complex 1 also undergoes
nucleophilic addition of hydride to give the bridging
methylene complex 3 which is formed (22% yield after
workup and chromatography) by the treatment of a
solution of 1 in toluene with an excess of Li[BHEt3].
Formation of 3 probably proceeds through the initial
nucleophilic attack of the hydride to one of the carbonyl
Crystal data for 4a : [C16H14Cl2O4Ru2Si]; Mr ) 571.40;
monoclinic; space group P21/n; a ) 7.731(2) Å, b ) 24.627(6)
Å, c ) 10.378(4) Å; â ) 90.89(3)°; V ) 1975(1) Å3; Fcalcd ) 1.921
g cm-3; F(000) ) 1112; µ ) 1.877 mm-1; red crystal (0.20 ×
0.20 × 0.16 mm); T ) 293(2) K; λ(Mo KR) ) 0.710 73 Å; 4051
reflections measured. The unit cell parameters were obtained
from the least-squares fit of 25 reflections (with θ between 15°
and 20°). The final drift correction factors were between 1.00
(7) Grant, D. F.; Gabe, E. J . J . Appl. Crystallogr. 1978, 11, 114.
(8) Lehman, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A 1974,
30, 580.
(9) Beurskens, P. T.; Beurskens, G.; Bosman, W. P.; Gelder, R. de;
Garc´ıa-Granda, S.; Gould, R. O.; Israe¨l, R.; Smits, J . M. M. The
DIRDIF-96 program system; University of Nijmegen: Nijmegen, The
Netherlands, 1996.
(10) Sheldrick, G. M. SHELXL97. Program for the Refinement of
Crystal Structures; University of Gottingen: Gottingen, Germany,
1997.
(11) International Tables for X-Ray Crystallography; Kynoch
Press: Birmingham, (present distributor: Kluwer Academic Publish-
ers: Dordrecht), 1974; Vol. IV.
(14) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.,
(12) Nardelli, M. J . Appl. Crystallogr. 1995, 28, 659.
(13) Spek, A. L. The EUCLID package. In Computational Crystal-
lography; Sayre, D., Ed.; Oxford: Clarendon Press, 1982; p 528.
Sect. A 1968, 24, 351.
(15) Parkin, S.; Moezzi, B.; Hope, H. J . Appl. Crystallogr. 1995, 28,
53.

Me2Si(η5-C5H4)2-Bridged Dinuclear Ru Complexes
Organometallics, Vol. 18, No. 16, 1999 3013
Ta ble 3. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for [Ru 2{µ-(η5-C5H4)2SiMe2}(Cl)2(CO)4]
(4a )a
Distances
Ru(1)-C(16)
Ru(1)-C(17)
Ru(1)-Cl(1)
C(16)-O(16)
C(17)-O(17)
C(11)-Si
1.904(8)
1.879(8)
2.406(2)
1.122(8)
1.137(8)
1.876(6)
1.860(6)
Ru(2)-C(26)
Ru(2)-C(27)
Ru(2)-Cl(2)
C(26)-O(26)
C(27)-O(27)
C(21)-Si
1.881(9)
1.891(7)
2.402(2)
1.141(9)
1.117(8)
1.868(7)
1.863(7)
Ru(1)-C*1
Ru(2)-C*2
Angles
C(17)-Ru(1)-C(16)
C(17)-Ru(1)-Cl(1)
C(16)-Ru(1)-Cl(1)
C(26)-Ru(2)-C(27)
C(26)-Ru(2)-Cl(2)
C(27)-Ru(2)-Cl(2)
C(21)-Si-C(11)
92.4(3) Cl(1)-Ru(1)-C*1
91.6(2) C(16)-Ru(1)-C*1
88.7(2) C(17)-Ru(1)-C*1
93.2(3) Cl(2)-Ru(2)-C*2
89.0(2) C(26)-Ru(2)-C*2
89.7(2) C(27)-Ru(2)-C*2
106.7(3)
123.6(2)
124.7(3)
125.4(3)
123.6(2)
122.8(3)
127.8(3)
F igu r e 1. ORTEP drawing of complex 4a with the atom-
numbering scheme.
groups as it has been reported for the formation of the
analogous [Ru2{µ-(η5-C5H4)2CH2}(µ-CH2)(µ-CO)(CO)2].4c
1H and 13C{1H} NMR data of 2 and 3 (Tables 1 and
2) are consistent with the presence of the hydride and
C*1 ) centroid of C(11), C(12), C(13), C(14), C(15). C*2
)
a
centroid of C(21), C(22), C(23), C(24), C(25).
1
methylene bridging groups. In particular the H NMR
spectrum of 2 shows a high-field singlet at δ ) -18.71
ppm due to the bridging hydride, while the resonances
of the methylene group in complex 3 appear as two
doublets at δ ) 7.00 and 8.94 ppm (2J HH ) 1.5 Hz). The
proton resonances of the cyclopentadienyl rings appear
as two sets of multiplets for complex 2 and four sets of
multiplets for complex 3 (Table 1) consistent with the
presence of the unsymmetrical double bridging system
µ-CH2, µ-CO.
Attempts to study the reactivity of complex 2 in
insertion reactions of alkynes such as MeO2CCt
CCO2Me and PhCtCPh were unsuccessful, leading
instead to decomposition products or to the parent
complex 1, respectively. In fact, complex 2 is trans-
formed reversibly to complex 1 by stirring a solution of
the former in acetone at room temperature or at the
temperature of refluxing toluene.
which are linked by the bridging Me2Si(η5-C5H4)2 group.
The ruthenium atoms are also bonded to two carbonyl
groups and one chloride group, showing typical Ru-C
(1.879(8)-1.904(8) Å) and Ru-Cl (2.402(2)-2.406(2) Å)
bonding distances. The most remarkable feature of the
molecular structure is the trans arrrangement of the
metal fragments leading to a long ruthenium-ruthe-
nium distance of 6.120(6) Å. The cyclopentadienyl rings
of the bridging ligand are rotated in opposite directions
around the Si-C(bridgehead) bond. This rotation can
be evaluated by the torsion angles Ru(1)C*(1)SiC*(2)
θ1 and Ru(2)C*(2)SiC*(1) θ2 (C* is the centroid of the
cyclopentadienyl ring), which are used2a to rationalize
the arrangement of the metal centers in the structures
of bimetallic Me2Si(η5-C5H4)2 bridged complexes. The
values of θ1 ) 173.4° and θ2 ) 42.5° in complex 4a are
in accordance with a transoid arrangement for the
ruthenium atoms. Such distortion can be also evaluated
by comparing the distances from the carbon atoms
adjacent to the bridgehead carbon C(12), C(15), C(22),
and C(25) (proximal carbons) to the plane defined by
Si-C(1)-C(2). These distances would be equal in a
symmetric situation but in complex 4a are as follows:
C(12), 2.075(6) Å; C(15), 2.158(6) Å; C(22), 1.806(7) Å;
C(25), 2.73(7) Å. The molecular structure of 4a is similar
to that found for the complex [{TiCl2(η5-C5Me5)}2{µ-(η5-
C5H4)2SiMe2)}],1a with distances from proximal carbons
to the plane Si-C-C being 1.65, 2.74, 2.17, and 1.75 Å,
which seems to reflect that the transoid form is the
lower energy rotamer in which the metal atoms are
located as far as possible.
It is well-known that the dimeric [M(η5-C5H5)(µ-CO)-
(CO)]2 (M ) Fe, Ru, Os) carbonyl derivatives readily
undergo oxidative additions of halogens to give metal(II)
halide carbonyl complexes. Similarly, complex 1 is
readily oxidized to give ruthenium(II) halide derivatives.
An equimolecular mixture of 1 and N-chlorosuccinimide
or X2 (X ) Br, I) in CH2Cl2 reacts at room temperature
to give complexes 4a -c (Scheme 1) (75-99% yield)
isolated as yellow air-stable solids. IR spectra (CH2Cl2
solutions) show the expected two ν(CO) strong absorp-
tions in the range 2052-2048 and 2005-1999 cm-1 due
to the formally cis dicarbonyl arrangement in a pseudo-
octahedral geometry. 1H NMR and 13C{1H} NMR show
resonances (Tables 1 and 2) in agreement with the
presence of the bridging Me2Si(η5-C5H4)2 group. In
particular the proton spectra at room temperature show
two sets of pseudotriplets at δ ) 5.44-5.65 ppm (3J HH
) 1.9 Hz) for the protons of each cyclopentadienyl ring,
consistent with an AA′BB′ spin system. This pattern
remains unchanged at low temperature (213 K). Since
the spectroscopic data does not provide information on
the relative orientation of both metal moieties, a single
X-ray crystal structural determination of 4a was carried
out.
The structure of complex 4a is fully consistent with
the proton NMR data although a fluxional process
involving a rapid rotation around the Me2Si-C bonds
even at 213 K cannot be discarded.
Reactivity of Com plexes [Ru 2{µ-(η5-C5H4)2SiMe2}-
(X)2(CO)4] (4a -c). Complexes 4a -c have been shown
to be good precursors for the preparation of novel
dinuclear ruthenium(II) derivatives through carbonyl
and halide substitution reactions.
(a) Syn th esis of Com plex [Ru 2{µ-(η5-C5H4)2SiMe2)}-
(CH3)2(CO)4] (5). Complex 4c reacts in THF with
lithium dimethylcuprate (prepared in situ) at room
temperature to give the methyl complex 5 isolated as a
brown oil (yield 82%). IR and 1H NMR spectroscopic
A view of the molecular structure is shown in Figure
1. Selected bond distances and angles are listed in Table
3. The crystal structure shows a three-legged piano-stool
geometry around each of the two ruthenium atoms,

3014 Organometallics, Vol. 18, No. 16, 1999
Frohlich et al.
data support this formulation. Thus, the IR spectrum
shows ν(CO) absorptions at 2012 and 1951 cm-1 and
the 1H NMR spectrum shows the methyl group reso-
nance at δ ) 0.24 ppm and the signals for the cyclo-
pentadienyl rings as two doublets at δ ) 4.62 and 4.77
(3J HH ) 2.2 Hz). Attempts to promote the formation of
acyl derivatives through migratory CO insertion by
refluxing 5 in the presence of excess PMe3 were unsuc-
cessful.
(b) Ca r bon yl Su bstitu ted Com p lexes [Ru 2{µ-(η5-
C5H4)2SiMe2}(I)2(L)x (CO)4-x], L ) P Cy3, x ) 2 (6c);
L ) CNCH2P h , x ) 1 (7a ), x ) 2 (7b), x ) 3 (7c), x )
4 (7d ); L ) CNCy, x ) 1 (8a ), x ) 2 (8b), x ) 3 (8c),
x ) 4 (8d ). Photolysis of complex 4c in the presence of
monodentate ligands leads to the substitution of car-
bonyl groups.
Thus, the irradiation of 4c with PCy3 in THF (3:1
molar ratio) for 9 h at -20 °C affords the complex
[Ru2{µ-(η5-C5H4)2SiMe2}(I)2(CO)2(PCy3)2] (6c) (50% yield).
The IR spectrum (CH2Cl2) shows the expected ν(CO)
absorption at 1951 cm-1. However, NMR spectroscopy
indicates the formation of two isomers (in ca. 1:1 ratio)
F igu r e 2. ORTEP view of the structure of the cationic
complex 10b with the atom-numbering scheme.
bridged dinuclear complexes [Ru2{µ-(η5-C5H4)2SiMe2}-
(µ-X)(CO)4][BF4] (X ) Cl (10a ); X ) Br (10b); X ) I
(10c)) isolated as air-stable solids (35-82% yield). It is
worth mentioning that the formation of complexes
10a -c occurs even in the presence of a large excess of
AgBF4, the second halide anion being inert toward the
silver salt. Elemental analyses, conductivity measure-
ments, and IR and NMR spectroscopy support the
proposed formulations. Thus, 1H NMR spectra show
only two triplets for the cyclopentadienyl protons (AA′BB′
spin system) and a singlet for the methyl group of the
ligand, as expected for a symmetrical arrangement (See
Tables 1 and 2).
1
(i.e., 31P{1H}: δ ) 57.0, 57.1 ppm; for H NMR spectrum
see Table 1). Although these species could not be
separated, they are identified as the complexes contain-
ing the phosphines in mutually cis and trans positions.
Similarly, complex 4c readily undergoes carbonyl
substitutions by π-acceptor isocyanide ligands. The
reactions, however, are not selective, leading instead to
a mixture of different carbonyl-isocyanide derivatives
whose nature depends on the ligand:complex ratio. The
reactions can be monitored by IR in the ν(CO) region,
and the irradiation is discontinued when the ν(CO)
absorptions of the starting complex disappear. Thus, the
irradiation of 4c with CNCH2Ph (1:2.5 molar ratio) in
THF for 5 h at -20 °C leads to a colored solution, from
which the substituted complexes 7a -c are obtained
after chromatographic workup (yields 4-10%). Similarly
complex 7d is obtained by using a complex:ligand molar
ratio of 1:10 (24% yield). Analogous complexes 8a -d are
isolated after chromatography from the irradiation of
complex 4c with CNCy (molar ratio 1:2). All of these
complexes were characterized by 1H NMR and IR
spectroscopy (See Experimental Section and Supporting
Information). IR spectra show the expected ν(CO) and
ν(CN) absorptions. (i) Monosubstituted complexes: ν(CN)
2172 (7a ), 2168 (8a ) cm-1; ν(CO) 2046, 1996, 1984 (7a ),
2046, 1996, 1979 (8a ) cm-1. (ii) Disubstituted com-
plexes: ν(CN) 2171 (7b), 2167 (8b) cm-1; ν(CO) 1982
(7b), 1978 (8b) cm-1. (iii) Trisubstituted complexes:
ν(CN) 2160, 2119 (7c), 2153, 2114 (8c) cm-1; ν(CO) 1980
(7c), 1976 (8c) cm-1. (iv) Tetrasubstituted complexes:
The structure of complex 10b has been confirmed by
X-ray diffraction. A view of the cation is shown in Figure
2, and the main bonding distances and angles are listed
in Table 4. Two different molecules have been found in
the asymmetric unit as well as a dichloromethane
solvent molecule of crystallization. The crystal structure,
as for complex 4a , shows the typical three-legged piano-
stool coordination around each of the ruthenium atoms
in a pseudooctahedral structure. Besides the presence
of the bridging Me2Si(η5-C5H4)2 group bonded in a η5
fashion, the coordination around each ruthenium atom
is completed by two carbonyl groups and the bromide
anion acting as a bridging ligand between the metal
atoms. Typical Ru-CO (1.84(1)-1.92(2) Å), Ru-C*
(1.85(1)-1.87(1) Å), and Ru-Br (2.529(1)-2.554(1))
bond lengths and angles (Ru2-Br1-Ru1 ) 108.21(5)°)
are observed. The structure also shows that the C5H4
rings of the ligand Me2Si(η5-C5H4)2 are not eclipsed,
leading instead to a staggered conformation of the two
three-legged piano-stool ruthenium moieties. The angles
θ1 and θ2 which are smaller than the corresponding ones
of the complex 4a show a different sign (θ1 ) 56.6(6),
θ2 ) -33.5(6)), indicating a cisoid arrangement leading
to a Ru-Ru distance of 4.114(1) Å, much smaller than
that in the complex 4a . The distances of the ring carbon
atoms C22, C25 and C15, C12 (proximal carbons) to the
SiC(1)C(2) plane also confirm the staggered conforma-
tion (cf. C(22), 2.01(1) Å; C(25), 2.67(1) Å; C(12), 2.75(1)
Å; C(15), 1.71(1) Å) and agree with the published data
for analogous endo-cis complexes.1b-f, 2c-f, 4a-d
ν(CN) 2156, 2117 (7d ), 2153, 2120 (8d ) cm-1
.
(c) Ca tion ic Com p lexes [Ru 2{µ-(η5-C5H4)2SiMe2}-
(CO)4(NCMe)2][BF4]2 (9)an d [Ru 2{µ-(η5-C5H4)2SiMe2}-
(µ-X)(CO)4][BF 4] (X ) Cl (10a ); X ) Br (10b); X ) I
(10c)). Cationic complexes were readily accessible
through halide abstraction when a large excess of AgBF4
was added to solutions of complexes 4a -c.
Thus, when acetonitrile was used as the solvent, the
dicationic complex 9 was isolated as the tetrafluoro-
borate salt from the reaction mixture, after the evapora-
tion of the solvent (42% yield). In contrast, the reactions
in acetone or dichloromethane lead to the double-

Me2Si(η5-C5H4)2-Bridged Dinuclear Ru Complexes
Organometallics, Vol. 18, No. 16, 1999 3015
Ta ble 4. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for
ligand:complex 4c. The halide complexes 4 have been
also used for the synthesis of novel cationic dinuclear
derivatives of the type [Ru2{µ-(η5-C5H4)2SiMe2}(CO)4-
(NCMe)2][BF4]2 (9) and [Ru2{µ-(η5-C5H4)2SiMe2}(µ-X)-
(CO)4][BF4] (10a -c) in which the ruthenium atoms are
linked both by the bridging Me2Si(η5-C5H4)2 group and
by one halide group. The cationic complexes are readily
formed from acetonitrile or dichloromethane solutions,
respectively, after treatment with AgBF4 as the halide
abstractor. It is interesting to note that we have found
no evidence of the breaking of the C-Si bond even when
photochemical conditions are used. In contrast, the
photolysis of the complex [Ru2{µ-(η5-C5H4)2SiMe2}(µ-
CO)2(CO)2] (1) for 2 h leads4e to the cleavage of one of
the C-Si bonds in the bridging ligand. The resulting
fragments, namely, Me2SiC5H4 and C5H4, are stabilized
through the coordination to the ruthenium atoms acting
as bridging systems to form the complex [{Ru(CO)2}2-
(µ-η5: η1κ-(Si)-C5H4SiMe2)(µ-η5: η1-C5H4)].
The structures of complexes [Ru2{µ-(η5-C5H4)2SiMe2}-
(Cl)2(CO)4](4a )and [Ru2{µ-(η5-C5H4)2SiMe2}(µ-Br)(CO)4]-
[BF4] (10b) which have been determined by X-ray
diffraction provide evidence, like other Me2Si(η5-C5H4)2-
bridged dinuclear complexes,1a,c of the tendency to locate
the ruthenium atoms mutually apart (transoid arrange-
ment) (4a ). It is apparent that only when a second
bridging halide group is present are the ruthenium
atoms located at a closer proximity (cisoid arrangement)
(10b). Further studies involving the reactivity of these
systems with unsaturated organic molecules are in
progress.
[Ru 2{µ-(η5-C5H4)2SiMe2}(µ-Br )(CO)4][BF 4] (10b)a
molecule 1
molecule 2
Distances
Ru(1)-C(16)
Ru(1)-C(17)
Ru(1)-Br(1)
C(16)-O(16)
C(17)-O(17)
C(11)-Si(1)
Ru(1)-C*1
Ru(2)-C(26)
Ru(2)-C(27)
Ru(2)-Br(1)
C(26)-O(26)
C(27)-O(27)
C(21)-Si(1)
Ru(2)-C*2
1.89(1)
1.92(2)
2.549(1)
1.13(1)
1.10(1)
1.88(1)
1.86(1)
1.88(1)
1.89(1)
2.529(1)
1.13(1)
1.16(1)
1.86(1)
1.85(1)
1.91(1)
1.84(1)
2.538(1)
1.11(1)
1.15(1)
1.88(1)
1.86(1)
1.91(1)
1.87(1)
2.554(1)
1.12(1)
1.13(1)
1.87(1)
1.87(1)
Angles
C(16)-Ru(1)-C(17)
C(16)-Ru(1)-Br(1)
C(17)-Ru(1)-Br(1)
C(26)-Ru(2)-C(27)
C(26)-Ru(2)-Br(1)
C(27)-Ru(2)-Br(1)
C(21)-Si(1)-C(11)
Br(1)-Ru(1)-C*1
C(16)-Ru(1)-C*1
C(17)-Ru(1)-C*1
Br(1)-Ru(2)-C*2
C(26)-Ru(2)-C*2
C(27)-Ru(2)-C*2
Ru(2)-Br(1)-Ru(1)
91.2(6)
87.9(4)
91.4(4)
90.7(6)
91.6(4)
90.7(6)
92.3(4)
92.2(4)
91.8(5)
90.7(4)
93.1(4)
91.2(4)
111.2(5)
126.5(4)
123.8(6)
125.1(6)
122.4(4)
126.7(5)
122.9(6)
108.21(5)
111.0(5)
122.6(3)
124.9(5)
124.7(6)
125.1(4)
123.9(6)
124.1(6)
108.16(5)
a
C*1 ) centroid of C(11), C(12), C(13), C(14), C(15). C*2
)
centroid of C(21), C(22), C(23), C(24), C(25).
Con clu sion s
Ack n ow led gm en t. This work was supported by the
Direccio´n General de Investigacio´n Cient´ıfica y Te´cnica
(Projects PB-96-0556 and PB-96-0558). We thank the
Spanish Ministerio de Educacio´n y Ciencia for a fellow-
ship to M.G.-C. and the European Erasmus Program
for a grant to R.F. (University of Graz, Austria).
In summary, Me2Si(η5-C5H4)2-bridged ruthenium(II)
halide complexes [Ru2{µ-(η5-C5H4)2SiMe2}(X)2(CO)4] (X
) Cl (4a ), Br (4b), and I (4c)) are suitable precursors
for the synthesis of new dinuclear ruthenium(II) deriva-
tives. Thus, carbonyl substitutions by the two-electron
ligands PCy3 and CNR take place in 4c under UV
irradiation to give neutral derivatives [Ru2{µ-(η5-C5H4)2-
SiMe2}(I)2(CO)2(PCy3)2] (6c) and [Ru2{µ-(η5-C5H4)2-
SiMe2}(I)2(CNR)x(CO)4-x] (R ) CH2Ph, x ) 1(7a ), x )
2(7b), x ) 3 (7c), x ) 4 (7d ); R ) Cy, x ) 1 (8a ), x ) 2
(8b), x ) 3 (8c), x ) 4 (8d )), the number of substituted
carbonyl groups being dependent on the molar ratio
Su p p or tin g In for m a tion Ava ila ble: Text and tables
giving details of the X-ray diffraction studies of 4a and 10b
1
and H NMR spectra for complexes 5, 7a -d , and 8a -d . This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM980547A