Stoichiometric reaction chemistry of cationic ruthenium silylene complexes toward polar and nonpolar organic substrates

Article abstract of DOI:10.1021/om300390n

Reactions of the cationic ruthenium silylene complexes [Cp*(P ⁱPr₃)Ru(H)₂(=SiRR′)][B(C ₆F₅)₄] (R = Mes, R′ = H, 1; R = R′ = Ph, 2) with alkenes, alkynes, ketones, and Lewis bases were explored. Addition of 1-hexene, 3,3-dimethylbut-1-ene, styrene, and cyclopentene to 1 afforded the disubstituted silylene products [Cp*(PⁱPr₃)Ru(H) ₂(=SiMesR)][B(C₆F₅)₄] (R = Hex, 3; R = CH₂CH₂^tBu, 4; R = CH₂CH ₂Ph, 5; R = C₅H₉, 6). Analogous reactions with 2-butyne and 3,3-dimethylbut-1-yne yielded the vinyl-substituted silylene complexes [Cp*(PⁱPr₃)Ru(H)₂(=Si(CR= CHR′)Mes)][B(C₆F)₄] (R = R′ = Me, 7; R = H, R′ = ^tBu, 8). Complex 1 undergoes reactions with ketones to give the heteroatom-substituted silylene complexes [Cp*(P ⁱPr₃)Ru(H)₂(=Si(OCHPhR)Mes)][B(C ₆F)₄] (R = Ph, 9; R = Me, 10). Interestingly, complexes 3-8 display a weak interaction between the hydride ligands and the silicon center, while 9 and 10 exhibit a relatively large interaction (as determined by ²J_SiH values). The reaction of isocyanates with 1 resulted in the silyl complexes [Cp*(PⁱPr₃)Ru(H) ₂(Si(Mes)[κ²-O(CH)(NC₆H ₄R)][B(C₆F₅)₄] (R = H, 11; R = CF₃, 12), and an intermediate in this transformation is observed. Complex 2 was subjected to various Lewis bases to yield the base-stabilized silylene complexes [Cp*(PⁱPr₃)Ru(H) ₂(SiPh₂?L)][B(C₆F)₄] (L = DMAP, 13; L = Ph₂CO, 14; L = PhCONH₂, 15; L = NHMePh, 16, L = ^tBuSONH₂, 18), and the reaction of 1 with NHMePh gave [Cp*(PⁱPr₃)Ru(H)₂(SiHMes?NHMePh)] [B(C₆F)₄].

Full text of DOI:10.1021/om300390n

Article
pubs.acs.org/Organometallics
Stoichiometric Reaction Chemistry of Cationic Ruthenium Silylene
Complexes toward Polar and Nonpolar Organic Substrates
Meg E. Fasulo and T. Don Tilley*
Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
ABSTRACT: Reactions of the cationic ruthenium silylene
complexes [Cp*(PiPr3)Ru(H)2(SiRR′)][B(C6F5)4] (R =
Mes, R′ = H, 1; R = R′ = Ph, 2) with alkenes, alkynes, ketones,
and Lewis bases were explored. Addition of 1-hexene, 3,3-
dimethylbut-1-ene, styrene, and cyclopentene to 1 afforded the
disubstituted silylene products [Cp*(PiPr3)Ru(H)2(
t
SiMesR)][B(C6F5)4] (R = Hex, 3; R = CH2CH2 Bu, 4; R =
CH2CH2Ph, 5; R = C5H9, 6). Analogous reactions with
2-butyne and 3,3-dimethylbut-1-yne yielded the vinyl-substituted
silylene complexes [Cp*(PiPr3)Ru(H)2(Si(CRCHR′)Mes)]-
t
[B(C6F)4] (R = R′ = Me, 7; R = H, R′ = Bu, 8). Complex 1
undergoes reactions with ketones to give the heteroatom-
substituted silylene complexes [Cp*(PiPr3)Ru(H)2(Si(OCHPhR)Mes)][B(C6F)4] (R = Ph, 9; R = Me, 10). Interestingly,
complexes 3−8 display a weak interaction between the hydride ligands and the silicon center, while 9 and 10 exhibit a relatively
2
large interaction (as determined by JSiH values). The reaction of isocyanates with 1 resulted in the silyl complexes
[Cp*(PiPr3)Ru(H)2(Si(Mes)[κ2-O(CH)(NC6H4R)][B(C6F5)4] (R = H, 11; R = CF3, 12), and an intermediate in this
transformation is observed. Complex 2 was subjected to various Lewis bases to yield the base-stabilized silylene complexes
[Cp*(PiPr3)Ru(H)2(SiPh2·L)][B(C6F)4] (L = DMAP, 13; L = Ph2CO, 14; L = PhCONH2, 15; L = NHMePh, 16,
t
L = BuSONH2, 18), and the reaction of 1 with NHMePh gave [Cp*(PiPr3)Ru(H)2(SiHMes·NHMePh)][B(C6F)4].
INTRODUCTION
Scheme 1
■
Transition metal silylene complexes, in which an :SiR2 fragment
is stabilized by coordination to a metal center, have been
proposed as intermediates in industrially significant organo-
silicon transformations.1 Since the isolation of the first base-free
silylene complexes in the late 1980s, significant research has been
undertaken to allow for access to a wider range of silylene species
through different synthetic routes.2 Concurrently, numerous
reactivity studies with silylene complexes have been con-
ducted.2,3 Notably, two silylene-based systems that catalyze the
hydrosilylation of olefins have been discovered: [Cp*(PiPr3)-
Ru(H)2(SiHPh·Et2O)][B(C6F5)4]4 and [PNPIrH(
SiHPh)][B(C6F5)4]5 (PNP = [N(2-PiPr2-4-Me-C6H3)2]−)
(Scheme 1). These catalysts operate by a novel mechanism
involving direct addition of the Si−H bond of the
silylene ligand to an olefin and give rise to unusually
high selectivities to anti-Markovnikov, secondary silane
products.6
A number of stoichiometric reactions of silylene complexes
with organic substrates have been reported,7,8 but at this stage it
remains difficult to make generalizations about such reactivity in
a predictive fashion. Such reactivity studies are expected to point
the way toward applications of silylene complexes in new
transformations and catalysis. The increasing number of
convenient synthetic procedures that provide access to silylene
complexes enables a broader examination of reactivity trends for
these species. Along these lines, recent research from this
laboratory has shown that the simple triflate complex Cp*-
(PiPr3)RuOTf is useful as a starting material for the convenient
syntheses of a broad range of cationic ruthenium silylene
Received: May 9, 2012
Published: July 5, 2012
© 2012 American Chemical Society
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complexes that are related to known hydrosilylation catalysts.9
These synthetic procedures involve activation of secondary or
primary silanes to form Cp*(PiPr3)Ru(H)2SiRR′OTf complexes,
followed by triflate abstraction with [Et3Si·toluene][B(C6F5)4]
to give silylene complexes of the general type [Cp*(PiPr3)Ru-
(H)2(SiRR′)][B(C6F5)4] (eq 1). The research described
silicon atom (2JSiH = 58.2 Hz), complex 3 lacks such a strong
interaction, as indicated by the small 2JSiH value of 10.9 ppm. The
29Si NMR resonance at 240.7 ppm remains in the downfield
region characteristic of a silylene ligand.2
In addition to 1-hexene, 1 reacts cleanly with 3,3-dimethylbut-
1-ene, styrene, and cyclopentene to yield the silylene complexes
4−6, respectively (eqs 2 and 3). As observed for 3, complexes
4−6 display resonances in the 29Si NMR spectra in the characteristic
below details a number of stoichiometric reactions of two
silylene complexes (1 and 2, eq 1) toward nonpolar and polar
organic substrates. Given the relation to known catalysts, the
study of stoichiometric reaction chemistry of 1 and 2 may result
in further understanding of known hydrosilylation catalysis or
the development of new catalytic transformations.
region for silylene complexes. The hydride ligands for these
2
complexes also exhibit small JSiH coupling constants (≤7 Hz),
indicating a weak interaction between the hydride ligands and the
silicon center. The NMR data for 1 and 3−6 are tabulated in
Table 1. Complexes 3−6 complement the previously reported
Table 1. NMR Data for Complexes 1 and 3−12
RESULTS AND DISCUSSION
■
δ
29Si
Reactions of [Cp*(PiPr3)Ru(H)2(SiHMes)][B(C6F5)4] (1)
with Alkenes and Alkynes. Several hydrogen-substituted
silylene complexes have been shown to undergo olefin insertion
into the Si−H bond of the silylene ligand,4,5 and this is a key Si−
C bond-forming step in catalytic alkene hydrosilylations. For the
direct addition of [Cp*(PiPr3)Ru(H)2(SiHPh·Et2O)]-
[B(C6F5)4] to 1-hexene, the product [Cp*(PiPr3)Ru(H)2(
SiPhHex)][B(C6F5)4] can be observed in solution by NMR
spectroscopy, but it has not proven to be amenable to isolation.
Thus, it was of interest to explore the reactivity of 1 toward an
array of unsaturated substrates, to gain further insight into the
mechanism of hydrosilylation by [Cp*(PiPr3)Ru(H)2
(SiHPh)]+.
complex
δ 1H (RuH) (2JSiH
)
(RuSi)
[Cp*(PiPr3)Ru(H)2(SiHMes)]+ (1)
−11.46 (58.2)
−11.65 (10.9)
226.5
240.7
[Cp*(PiPr3)Ru(H)2(Si(Hexyl)Mes)]+
(3)
t
[Cp*(PiPr3)Ru(H)2(Si(CH2CH2 Bu)
−11.64 (<7)
−11.61 (<7)
278.9
277.6
Mes)]+ (4)
[Cp*(PiPr3)RuH2(Si(CH2CH2Ph)
Mes)]+ (5)
[Cp*(PiPr3)RuH2(Si(C5H9)Mes)]+ (6) −11.64 (<7)
215.0
301.4
[Cp*(PiPr3)Ru(H)2(Si(CMeCHMe) −11.02 (14.1)
Mes)]+ (7)
[Cp*(PiPr3)Ru(H)2(Si(CHCHtBu)
Mes)]+ (8)
−11.46 (<7)
282.3
204.4
[Cp*(PiPr3)Ru(H)2(Si(OCHPh2)
−11.18 (38.3)
Mes)]+ (9)
To a solution of complex 1 in C6H5F was added an excess of
1-hexene, resulting in an immediate color change from bright
orange to bright yellow (eq 2). After stirring for 5 min, the
[Cp*(PiPr3)Ru(H)2(Si(OCHPhMe)
Mes)]+ (10)
−11.27, −11.49 (41.7) 199.7
[Cp*(PiPr3)Ru(H)2(SiMes{η2-O(CH)
−11.41, −11.59 (<7)
−11.33, −11.48 (<7)
71.7
75.8
(NPh)})+ (11)
[Cp*(PiPr3)Ru(H)2(SiMes{η2-O(CH)
(NPhCF3)})]+ (12)
trend established for complexes of the type [Cp*(PiPr3)Ru-
(H)2(SiRR′)][B(C6F)4], that H-substituted silylene com-
plexes have much stronger Ru−H···Si interactions in comparison
to disubstituted silylene complexes, as indicated by 2JSiH coupling
constants.9 Presumably, H-substituted silylene complexes can
readily adopt a conformation that maximizes donation of the two
hydride ligands into the 3p orbital associated with the silicon
center (silylene plane parallel to the Ru−Cp* centroid vector),
whereas two substituents at silicon enforce a rotation about the
Ru−Si bond and less favorable hydride−silicon interactions.10
Especially in light of the unusual silylene-mediated catalysis
reported for [Cp*(PiPr3)Ru(H)2(SiHPh·Et2O)][B(C6F5)4],4
it is of interest to explore the propensity of other unsaturated
substrates to undergo insertion into the Si−H bond of 1. Despite
their similarity to alkenes, the reactivity of silylene complexes
toward alkynes has remained relatively unexplored. An excess of
2-butyne was added to a solution of 1 in C6H5F, and the solution
reaction solution was reduced under vacuum to give a dark
yellow oil. Subsequent washings with hexanes and further drying
under vacuum resulted in [Cp*(PiPr3)Ru(H)2(Si(Hex)-
Mes)][B(C6F)4] (3) as a bright yellow solid. Complex 3
decomposes in solution over 8 h but is stable as a solid for ca. 1
week at −30 °C.
Multinuclear NMR spectroscopy confirms the identity of 3,
and 1H NMR spectroscopy reveals loss of the Si−H resonance
for 1 (at 7.99 ppm). Additionally, new resonances between 1.44
and 1.27 ppm confirm the presence of a hexyl substituent. The
two equivalent hydride ligands appear at −11.65 ppm. Notably,
while the hydride ligands of 1 exhibit a strong coupling to the
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immediately became a golden yellow color (eq 4). The product,
followed by transfer of the metal hydride to the carbonyl carbon,
and finally migration of the hydride from Si to Ru.8f
[Cp*(PiPr3)Ru(H)2(Si(CMeCHMe)Mes)][B(C6F)4]
A solution of 1 equiv of benzophenone in C6H5F was added to
an orange solution of 1 in C6H5F, giving an immediate color
change to yellow. This color change is consistent with formation
of a secondary silylene complex via insertion into the Si−H bond
of 1. Addition of hexanes to the solution resulted in precipitation
of a dark yellow oil, and further hexane washes and drying under
vacuum afforded a light brown solid identified as [Cp*(PiPr3)-
1
Ru(H)2(Si(OCHPh2)Mes)][B(C6F)4] (9, eq 5). The H
(7), was isolated as a yellow solid using a procedure analogous to
that used for 3−6. Similarly, [Cp*(PiPr3)Ru(H)2(Si(CH
CHtBu)Mes)][B(C6F)4] (8) was prepared via reaction of 1 with
3,3-dimethylbut-1-yne. Complexes 7 and 8 represent the first
examples of vinyl-substituted silylene complexes.
The structure of 7 was confirmed through multinuclear and
2D NMR experiments. The 1H NMR spectrum reveals a quartet
at 6.42 ppm corresponding to the vinylic proton, a doublet
(J = 6.6 Hz) at 1.76 ppm arising from the methyl group trans to
Si, and a singlet at 1.68 due to the geminal methyl group. The
methyl groups were determined to be in a cis conformation with
respect to one another based on observed correlations in a 2D
1H−1H NOESY experiment. The hydride ligands remain
equivalent (−11.02 ppm) and are associated with a 2JSiH coupling
constant value of 14.1 Hz. This small coupling constant indicates
that strong interactions between the hydride and silylene ligands
are no longer present. The silylene ligand remains intact, as
confirmed by 29Si NMR spectroscopy (301.4 ppm).
By similar NMR experiments, the structure of 8 was
determined. The two vinylic protons give rise to two doublets
(J = 18.2 Hz) at 6.39 and 6.25 ppm in the 1H NMR spectrum.
The large H−H coupling constant indicates the presence of a
trans alkene. The hydride ligands at −11.46 ppm display no
observable 2JSiH to the silicon center (≥7 Hz), and the 29Si NMR
spectrum contains a resonance for the silylene ligand at 282.3
ppm. Thus, the reaction of 1 with 3,3-dimethylbut-1-yne is highly
selective and produces only the trans alkene, anti-Markovnikov
addition product. This selectivity is likely due to steric
interactions between 1 and the incoming alkyne, with the
bulky tert-butyl group enforcing the formation of only 8. Notably,
alkynes with two bulky substituents, such as diphenylacetylene,
gave no reaction at room temperature in C6D5Br after 4 h.
Prolonged reactions times and gentle heating resulted in
decomposition of the parent silylene 1.
Reactions of 1 with Ketones. Several H-substituted silylene
complexes have been reported to react with carbonyl-containing
organic substrates,7f,8a,g with most of the products resulting from
simple addition of the Si−H bond across the CO bond of the
carbonyl compound. For example, [(PNP)(H)IrSiHMes][B-
(C6F5)4] reacts with 1 equiv of benzophenone to give
[(PNP)(H)IrSiMes(OCHPh2)][B(C6F5)4].7f In constrast,
reaction of [(PNP)(H)IrSiHMes][B(C6F5)4] with 1 equiv
of acetophenone affords the enolate-substituted silyl complex
[(PNPH)IrH(SiPh2(OC(CH2)Ph))][B(C6F5)4]. Interest-
ingly, all reports of reactions of a silylene complex with an
enolizable ketone describe similar enolate-based products.7f,8f
The neutral complex Cp*(CO)(H)RuSi(H)[C(SiMe3)3]
undergoes a net Si−H insertion reaction with ketones to give
secondary silylene complexes of the type Cp*(CO)(H)Ru
Si(OCHRR′)[C(SiMe3)3], and this reaction is proposed to
proceed via coordination of the ketone to the electrophilic Si,
NMR spectrum of 9 contains a resonance at 5.85 ppm
corresponding to the CHPh2 proton, which correlates to a
13C{1H} resonance at 83.9 ppm, observed with use of a 2D 1H,
13C{1H} HMQC experiment. The equivalent ruthenium hydride
ligands appear at −11.18 ppm. Interestingly, the hydride ligands
in 9 retain strong interactions with the silicon center, as
2
suggested by the relatively large JSiH value of 38.3 Hz.
Additionally, while the 29Si NMR resonance at 204.4 ppm
remains in the region usually associated with silylene ligands, it
has shifted somewhat upfield from the corresponding resonances
for 1−9.
In complexes 2−8, the presence of a strong, secondary Ru−
H···Si interaction, as indicated by a large 2JSiH value, appears to
require the presence of a hydrogen substituent at silicon.
Complex 9 is the first disubstituted silylene complex in the
Cp*(PiPr3)Ru(H)2(SiRR′)][B(C6F)4] family that maintains
this interaction. The existence of a large 2JSiH for 9 indicates that
inductive effects dominate the Si−O bonding, resulting in an
electrophilic silicon center, and any π-donation from O to Si is
negligible. Interestingly, other heteroatoms, such as sulfur, have
been shown to donate electron density from lone pairs to the
electropositive Si atom, stabilizing the silylene ligand. In fact, the
first isolated, base-free silylene complexes featured heteroatoms
on the silylene ligand.11
The reaction of 1 with acetophenone occurred under
analogous conditions and gave a light green solid. Multinuclear
and 2D NMR experiments allowed for this complex to be
identified as {Cp*(PiPr3)Ru(H)2[Si(OCHPhMe)Mes]}[B-
1
(C6F)4] (10), rather than an enolate product. The H NMR
spectrum is very similar to that of 9. The resonance that arises
from the CHPhMe proton at 4.81 ppm is a quartet (J = 6.6 Hz)
due to splitting by the CHPhMe methyl group, which appears at
1.46 ppm as a doublet. These two resonances unambiguously
1
integrate in a 1:3 ratio, as expected. Additionally, a 2D H,
13C{1H} HMQC experiment revealed that the CHPhMe proton
correlates to a resonance in the 13C{1H} NMR spectrum at 78.4
ppm. The hydride ligands appear at −11.27 and −11.49 ppm and
retain a strong coupling to the silicon atom (2JSiH = 41.7 Hz).
Interestingly, unlike complexes 1−9, the hydride ligands are
inequivalent, presumably due to the presence of three unique
substituents on the silyl ether substituent (OCHPhMe). The 29Si
NMR resonance associated with the silicon center shifts upfield
upon addition to the ketone, to 199.7 ppm.
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Reactions of 1 with Isocyanates. Reactions of a silylene
complex with an isocyanate substrate have been demonstrated to
occur in one of two ways, as depicted in Scheme 2. The first
8.33−8.78 ppm)13 as well as the silacycle products observed for
the reactions of [Cp*(PMe3)2RuSiR2][B(C6F5)4]7a and
Cp*(CO)(H)RuSiH[C(SiMe3)3]8i with isocyanates. The
ruthenium hydrides are diastereotopic due to the new chiral Si
center (−11.41, −11.59 ppm) and display no observable
coupling to silicon. The 29Si NMR spectrum supports the
formulation of 11, as it contains an upfield-shifted resonance at
71.7 ppm, in the range for a metal-silyl or base-stabilized silylene
complex.14 Presumably, given the relatively low-field 29Si NMR
shift for this complex, the positive charge in the complex is
delocalized significantly onto the κ2-formamidate ligand, via the
resonance structures depicted in eq 6. Additionally, IR
spectroscopy reveals a stretch at 1608 cm−1 associated with a
chelating amidate group.15 This compares favorably to that
observed for {Cp*(PMe3)2Ru)[κ2-O(CSTol)(NMe)]}[B-
(C6F5)4]7a (1625 cm−1), which supports the formulation for
11 given in eq 6. Complex 12, exhibiting a structure analogous to
that of 11 (by NMR spectroscopy), was synthesized similarly (eq 6).
The 29Si NMR resonance for 12 appears at 75.8 ppm, and the
hydride ligands (−11.33, −11.48 ppm) exhibit no observable
coupling to Si.
Scheme 2
An intermediate in the formation of 11 and 12 was observed at
short (5 min) reaction times after addition of the isocyanate to a
solution of 1 in C6D5Br at room temperature. In both
experiments, the reactions were observed to proceed initially to
two species, one of which is the final product. Allowing the
solutions to stand at room temperature for 1 h results in
complete conversion to the final product. In the case of phenyl
isocyanate, one product can be identified as 11 and the other is
possible reaction pathway involves a formal [2+2] cycloaddition,
while the second involves insertion into an Si−H bond. The
silylene system [Cp*(PMe3)2RuSiR2][B(C6F5)4] (R = Me,
Ph, STol) has been reported to undergo both types of reactions
with isocyanates.7a Additionally, reaction of the neutral silylene
complex Cp*(CO)(H)Ru[SiHC(SiMe3)3] with isocyanates
results in reduction of the carbonyl group and formation of
complexes featuring five-membered Ru−Si−O−CH−N(Ar)
metallacyclic rings.8i
An excess of phenyl isocyanate was added to a solution of 1 in
C6H5F, resulting in an immediate color change from bright
orange to light yellow. The solution was allowed to stir at
ambient temperature for 1 h before the volatile materials were
removed in vacuo. The resulting dark yellow oil was washed with
hexanes and further dried to give a light yellow solid, identified as
{Cp*(PiPr3)(H)2RuSiMes[κ2-OCH(NPh)]}[B(C6F5)4] (11)
(eq 6). The new substituent at silicon is formulated as a
1
speculated to be an isomer of the final product (11a). The H
NMR spectrum of the reaction mixture contains a new CH
resonance that is associated with 11a at 7.85 ppm that displays
weak coupling to Si (2JSiH ≤ 7 Hz). Importantly, this CH
resonance correlates to the imidate tautomer of (organosilyl)-
formanilides (PhNCHOSiR1R2R3: 7.22−7.78 ppm),13 which
suggests that 11a might be formulated as {Cp*(PiPr3)-
(H)2RuSiMes[κ1-OCH(NPh)]}[B(C6F5)4] or {Cp*(PiPr3)-
(H)2RuSiMes[κ1-NPhCHO)]}[B(C6F5)4]. The 31P NMR spec-
trum contains two resonances at 76.0 ppm for 11 and 74.1 ppm
for 11a. The most striking difference between 11 and 11a is
revealed by the 29Si NMR spectrum with a new resonance at
116.3 ppm, indicating that 11a retains more silylene character
than the final product 11. At room temperature, 11 and 11a are
initially present in a 1:2 ratio, with no 1 remaining, indicating that
11a might be the kinetic product. Interestingly, heating the
solution to 40 °C for 30 min increases the amount of 11a to a
maximum ratio of 1:6 (11/11a), indicating that 11 is in
equilibrium with 11a. It was not possible to observe or isolate
pure 11a due to its conversion to 11, which precludes
identification of this isomer. The reaction to form complex 12
behaves analogously and gives rise to the intermediate/isomer
12a, which displays a transient 29Si resonance at 118.0 ppm.
Given that both free tautomers of (organosilyl)formanilides can
be observed by NMR spectroscopy, it seems reasonable to
attribute similar structures to 11a and 12a.
κ2-formamidate group, on the basis of multinuclear NMR
Reactions of [Cp*(PiPr3)Ru(H)2(SiPh2)][B(C6F5)4] (2)
with Unsaturated Lewis Bases. For comparative purposes, it
was of interest to examine reactions of unsaturated organic
substrates with the disubstituted silylene complex [Cp*(PiPr3)-
Ru(H)2(SiPh2)][B(C6F5)4] (2).9 The diphenyl silylene
complex was chosen because of its relative stability and ease of
synthesis. One common mode of reactivity for silylene
complexes is coordination of Lewis bases to the Lewis acidic
1
spectroscopy. The H NMR spectrum of 11 contains a new
signal at 8.14 ppm that correlates to a downfield resonance in the
1
13C{1H} NMR spectrum at 165.8 ppm (by a 2D H, 13C{1H}
HMQC experiment). This signal is attributed to a new CH
moiety formed by insertion of the isocyanate into the Si−H bond
and corresponds closely to previously synthesized amide tauto-
mers of (organosilyl)formanilides (OCH-N(Ph)SiR1R2R3:
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silicon center.15,16 Consistent with this, addition of 1 equiv of
N,N-dimethylaminopyridine (DMAP) to a solution of complex 2
in fluorobenzene resulted in reaction to give a colorless solution.
Drying under vacuum resulted in a white solid identified as the base-
stabilized silylene complex [Cp*(PiPr3)Ru(H)2(SiPh2·DMAP)]-
[B(C6F)4] (13, eq 7). By 1H NMR spectroscopy, the resonance
was isolated. As observed for complex 13, both the hydride
ligands (−11.06 ppm) and silicon resonance (78.3 ppm) appear
significantly upfield from the corresponding resonances for 2.
A silyl ether product, as proposed in Scheme 3C, may be ruled out
by the integration of the hydride ligands and the lack of a new CH
resonance. A metallocycle can also be eliminated as a possibility due
to the observation of a downfield peak (201.9 ppm) in the 13C NMR
spectrum associated with OCPh2. This resonance has shifted very
little from that of free benzophenone (ca. 197 ppm).
for the hydride ligands (−11.92 ppm) appears upfield relative to
the hydride resonance for 2 (−9.11 ppm). The DMAP
significantly reduces the electron deficiency of the silylene
ligand, as evidenced by a drastic upfield shift in the 29Si NMR
resonance to 68.5 ppm.
Having established that 2 interacts as expected with the simple
Lewis base DMAP, a wider range of Lewis basic functionalities
were explored. Benzophenone is an interesting case (Scheme 3),
Another substrate that can be anticipated to have multiple
modes of reactivity is benzamide. The CO could bind to the
silylene ligand to form a base-stabilized silylene complex, while
the NH2 group could add across the RuSi bond, as observed
for the reaction of [(PNP)(H)IrSiPh2][B(C6F5)4] with
anilines.7f The reaction of 2 with benzamide yields a white
solid ascertained to be the base-stabilized silylene complex
[Cp*(PiPr3)Ru(H)2(SiPh2·PhCONH2)][B(C6F)4] (15). Again,
the 29Si NMR spectrum reveals a resonance at 80.2 ppm, in the
region associated with silyl and base-stabilized silylene ligands.
The hydride ligands are shifted significantly upfield (−11.50
ppm) from those for 2, and only a small coupling to the silicon
center is observed (JSiH = 11.3 Hz). The N-H resonances are
inequivalent and appear at 5.90 and 5.62 ppm. This
inequivalency may be indicative of delocalization of the positive
charge onto the N atom of benzamide (and CN character).
Gentle heating of 15 in C6D5Br results in decomposition of the
complex rather than N−H activation.
Scheme 3
To determine whether or not 2 has the ability to activate N−H
bonds, complex 2 was treated with an excess of N-methylaniline
to afford the off-white compound [Cp*(PiPr3)Ru-
(H)2(SiPh2·NHMePh)][B(C6F)4] (16). The NH proton,
1
observed as a broad singlet at 4.37 ppm in the H NMR
spectrum, indicates that activation of the N−H bond has not
occurred. The hydride ligands appear at −11.14 ppm and do not
2
exhibit observable JSiH coupling. The 29Si NMR resonance of
55.7 ppm is in the range typical for base-stabilized silylene com-
plexes. This result is somewhat surprising on the basis of literature
precedents for N−H and O−H bond activations by silylene
complexes.3,7f For example, reaction of [(PNP)(H)IrPh2]-
[B(C6F5)4] with aniline results in [(PNPH)IrH(SiPh2NHPh)]-
[B(C6F5)4],7f and [Cp*(PMe3)2RuSiPh2(NCMe)][BPh4]
reacts with various alcohols (ROH) to give a silyl ether product,
Ph2SiH(OR).17 Interestingly, the same type of base-stabilized
silylene complex is formed in the reaction of 1 with N-
methylaniline, [Cp*(PiPr3)Ru(H)2(SiHMes·NHMePh)][B-
(C6F)4] (17). The NMR spectroscopic data for complex 17
differ very little from 16, with a broad NH peak at 5.17 ppm,
upfield shifted hydride ligands at −12.16 ppm, and a 29Si NMR
resonance at 35.7 ppm. As observed for 15, gentle heating of 16
and 17 in C6D5Br results in decomposition.
as it can be envisioned to simply coordinate to the silylene ligand
of 2 (reaction A), engage in a cycloaddition to give a metallocyclic
product (reaction B),7a or undergo attack by a hydride ligand to
produce a silyl ether linkage7c (reaction C). The reaction of 1
equiv of benzophenone with 2 in fluorobenzene gave a bright
orange solution, from which the orange, base-stabilized silylene
complex [Cp*(PiPr3)Ru(H)2(SiPh2·Ph2CO)][B(C6F)4](14, eq 8)
The reaction of 2 with the chiral substrate (S)-tert-
butylsulfinamide gave the base-stabilized silylene complex
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[Cp*(PiPr3)Ru(H)2(SiPh2·tBuSONH2)][B(C6F)4] (18) as an
off-white solid (eq 9). As with complexes 13−17, the
stoichiometrically and catalytically activates N−H and O−H
bonds. Interestingly, the PNP pincer ligand plays a significant,
non-innocent role in the observed reactivity of the iridium
complex, as the amide is protonated during these reactions. Thus,
the modes of reactivity available for a secondary silylene ligand
appear to be highly dependent on additional ligands present in
the complex. Note that reactions of secondary silylene complexes
in hydrosilylation catalysis are important in defining selectivity
and the key transformation to products.2,4,5,19
Importantly, key differences in reactivity trends also exist for
the comparison between neutral and cationic silylene complexes.
While neutral hydrogen-substituted silylene complexes have
been demonstrated to undergo novel stoichiometric reactions
with a number of polar organic substrates,8 they have not yet
been observed to react with nonpolar substrates (alkenes and
alkynes) and, thus, do not catalyze the hydrosilylation of olefins.
inequivalent hydride ligands (−11.04, −11.23) for complex 18
are shifted upfield relative to 2 and do not display observable
coupling to the Si center. The hydride ligands are likely
inequivalent due to coordination of a chiral Lewis base, as the
hydride ligands of complexes 2 and 13−17 appear equivalent.
The 29Si NMR spectrum displays a resonance at 89.6 ppm. To
determine which functional group of the sulfinamide is bound to
the silylene ligand, an infrared spectrum was taken. The IR bands
at 3419 and 3327 cm−1 arising from the NH2 group are similar to
those of free tert-butylsulfinamide (3324 and 3218 cm−1).18
A new band observed at 1018 cm−1 is attributed to the SO group.
The shift (from 1030 cm−1 in free tert-butylsulfinamide) is
associated with significant electron donation to the electon-
deficient silylene ligand. This result is in agreement with the
previously discussed complex 16. The NMR data for complexes
13−18 are summarized in Table 2.
EXPERIMENTAL SECTION
■
General Considerations. All experiments were carried out under a
nitrogen atmosphere using standard Schlenk techniques or an inert
atmosphere (N2) glovebox. Olefin impurities were removed from
pentane by treatment with concentrated H2SO4, 0.5 N KMnO4 in 3 M
H2SO4, and then NaHCO3. Pentane was then dried over MgSO4, stored
over activated 4 Å molecular sieves, and dried over alumina. Thiophene
impurities were removed from benzene and toluene by treatment with
H2SO4 and saturated NaHCO3. Benzene and toluene were then dried
over CaCl2 and further dried over alumina. Tetrahydrofuran, diethyl
ether, dichloromethane, and hexanes were dried over alumina.
Fluorobenzene was dried over P2O5, degassed, and distilled under N2.
Methylene chloride-d2 was dried by vacuum distillation from CaH2.
Benzene-d6 was dried by vacuum distillation from Na/K alloy.
Bromobenzene-d5 was refluxed over CaH2 for 20 h and then distilled
under nitrogen. The complexes [Cp*(PiPr3)Ru(H)2(SiHMes)][B-
(C6F)4] (1) and [Cp*(PiPr3)Ru(H)2(SiPh2)][B(C6F)4] (2) were
prepared according to literature methods.9 All other chemicals were
purchased from commercial sources and used without further
purification.
Table 2. NMR Data for Complexes 2 and 13−18
δ
29Si
complex
δ 1H (RuH)
(RuSi)
[Cp*(PiPr3)RuH2(SiPh2)]+ (2)
−9.11
−11.92
−11.06
339.0
68.5
78.3
80.2
55.7
89.6
[Cp*(PiPr3)RuH2(SiPh2·DMAP)]+ (13)
[Cp*(PiPr3)RuH2(SiPh2·Ph2CO)]+ (14)
[Cp*(PiPr3)RuH2(SiPh2·PhCONH2)]+ (15) −11.50
NMR spectra were recorded using Bruker AVB 400, AV-500, or AV-
600 spectrometers equipped with a 5 mm BB probe. Spectra were
recorded at room temperature and referenced to the residual protonated
solvent for 1H. 31P{1H} NMR spectra were referenced relative to 85%
H3PO4 external standard (δ = 0). 19F{1H} NMR spectra were referenced
relative to a C6F6 external standard. 13C{1H} NMR spectra were
calibrated internally with the resonance for the solvent relative to
tetramethylsilane. For 13C{1H} NMR spectra, resonances obscured by
the solvent signal are omitted. 29Si NMR spectra were referenced relative
[Cp*(PiPr3)RuH2(SiPh2·NHMePh)]+ (16)
[Cp*(PiPr3)RuH2(SiPh2·tBuSONH2)]+ (18) −11.04, −11.25
−11.14
In addition to a variety of Lewis bases, solutions of complex 2
in C6D5Br were subjected to alkenes, alkynes, isocyanates,
amines, and alcohols. In a typical experiment, no reaction was
observed by multinuclear NMR spectroscopy at room temper-
ature, and decomposition of 2 was observed upon gentle heating
of the reaction mixture.
1
to a tetramethylsilane standard and obtained via 2D H 29Si HMBC
unless specified otherwise. The following abbreviations have been used
to describe peak multiplicities in the reported NMR spectroscopic data:
“m” for complex multiplet and “br” for broadened resonances. In
13C{1H} NMR spectra, resonances obscured by the solvent signal are
omitted. Elemental analyses were performed by the College of
Chemistry Microanalytical Laboratory at the University of California,
Berkeley.
CONCLUSION
■
Silylene complexes of the type [Cp*(PiPr3)Ru(H)2(SiRR′)]-
[B(C6F5)4] have been observed to display two main types of
reactivity. Complex 1, a hydrogen-substituted silylene complex,
favors insertion chemistry involving the Si−H bond. Both polar
and nonpolar substrates have been demonstrated to activate the
Si−H bond of the silylene ligand, resulting in secondary silylene
complexes, and these reactions are typically instantaneous at
room temperature. The conversions to complexes 3−10 allow
further insight into the mechanism of silylene-mediated
hydrosilylations and suggest new possibilities for catalytic
reactions. Complex 1 is currently being evaluated for its ability
to perform catalytic hydrosilylations of olefin, alkyne, and ketone
substrates.
[Cp*(PiPr3)Ru(H)2(Si(Hex)Mes)][B(C6F)4] (3). An excess of
1-hexene (ca. 0.1 mL) was added to a solution of 1 (0.050 g, 0.04 mmol)
in 1 mL of C6H5F to give a bright yellow solution. After 5 min, the
reaction mixture was evaporated to dryness under vacuum. The resulting
oil was washed with 3 aliquots of hexanes (ca. 10 mL) and then dried
under vacuum to give a bright yellow solid in 87% yield (0.046 g). 1H
NMR (C6D5Br, 600 MHz): δ 6.95 (2H, s, ArH), 2.45 (6H, s, ArCH3),
2.37 (3H, s, ArCH3), 2.09 (3H, br s, CH(CH3)2), 1.55 (15H, s, C5Me5),
1.44 (2H, m, CH2), 1.39 (2H, m, CH2), 1.34 (2H, m, CH2), 1.27 (4H, m,
CH2), 1.16 (18H, dd, J = 6.3 Hz, JPH = 13.6 Hz, CH(CH3)2), −11.65
(2H, d, 2JPH = 15.4 Hz, 2JSiH = 10.9 Hz, RuH). 13C{1H} NMR (C6D5Br,
150.9 MHz): 149.7 (ArC), 148.0 (ArC), 142.2 (ArC), 139.5 (ArC),
138.7 (ArC), 138.3 (ArC), 137.6 (ArC), 135.9 (ArC), 134.9 (ArC),
128.9 (ArC), 98.2 (C5Me5), 34.9 (Hexyl), 32.6 (Hexyl), 31.9 (Hexyl),
Reactions of the secondary silylene complex 2 are dominated
by its behavior as a strong Lewis acid, even with protic substrates.
This is in contrast to [(PNP)(H)IrPh2][B(C6F5)4], which
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31.3 (Hexyl), 27.5 (CH(CH3)2), 27.3 (CH(CH3)2), 25.6 (Hexyl), 23.9
(Hexyl), 23.0 (ArMe), 22.9 (ArMe), 19.5 (CH(CH3)2), 10.7 (C5Me5).
31P{1H} NMR (C6D5Br, 163.0 MHz): δ 68.9. 29Si NMR (C6D5Br, 99.4
MHz): δ 240.7. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.3,
−162.9, −166.6. Anal. Calcd for C58H62BF20PRuSi·2/3(C6H5F): C,
54.19; H, 4.79. Found: C, 54.34; H, 4.78.
[Cp*(PiPr3)Ru(H)2(Si(CHCHtBu)Mes)][B(C6F)4] (8). By a
procedure analogous to that for 3, complex 8 was obtained as a bright
1
yellow solid in 85% yield (0.045 g). H NMR (C6D5Br, 600 MHz): δ
6.97 (2H, s, ArH), 6.39 (1H, d, J = 18.2 Hz, SiCH), 6.25 (1H, d, J = 18.2
Hz, CHtBu), 2.43 (6H, s, ArCH3), 2.36 (3H, s, ArCH3), 2.10 (3H, m,
CH(CH3)2), 1.62 (15H, s, C5Me5), 1.16 (18H, dd, J = 6.9 Hz, JPH = 13.8
Hz, CH(CH3)2), −11.46 (2H, d, 2JPH = 17.4 Hz, RuH). 13C{1H} NMR
(C6D5Br, 150.9 MHz): 170.9 (CHSi), 149.4 (ArC), 147.7 (ArC), 142.3
(ArC), 139.6 (ArC), 139.1 (ArC), 137.4 (ArC), 135.7 (ArC), 98.5
(C5Me5), 27.6 (tBu), 27.2 (CH(CH3)2), 27.0 (CH(CH3)2), 22.9
(ArMe), 21.1 (ArMe), 19.0 (CH(CH3)2), 10.4 (C5Me5). 31P{1H} NMR
(C6D5Br, 163.0 MHz): δ 70.6. 29Si NMR (C6D5Br, 99.4 MHz): δ 282.3.
19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.6, −163.2, −166.9. Anal.
Calcd for C58H60BF20PRuSi: C, 53.26; H, 4.62. Found: C, 53.13; H,
4.35.
t
[Cp*(PiPr3)Ru(H)2(Si(CH2CH2 Bu)Mes)][B(C6F)4] (4). By a
procedure analogous to that for 3, complex 4 was obtained as a bright
orange solid in 94% yield (0.050 g). 1H NMR (C6D5Br, 600 MHz): δ
6.91 (2H, s, ArH), 2.43 (6H, s, ArCH3), 2.31 (3H, s, ArCH3), 2.09 (3H,
br s, CH(CH3)2), 1.53 (15H, s, C5Me5), 1.47 (2H, m, 2JSiH = 6.36 Hz,
CH2), 1.21 (2H, m, 2JSiH = 15.5 Hz, SiCH2), 1.15 (18H, dd, J = 6.2 Hz,
2
JPH = 12.5 Hz, CH(CH3)2), −11.64 (2H, d, JPH = 16.1 Hz, RuH).
13C{1H} NMR (C6D5Br, 150.9 MHz): 149.6 (ArC), 148.0 (ArC), 142.3
(ArC), 139.4 (ArC), 138.6 (ArC), 137.5 (ArC), 135.9 (ArC), 98.3
(C5Me5), 37.2 (CH2), 30.9 (CH2), 28.9 (tBu), 28.3 (tBu), 27.5
(CH(CH3)2), 27.3 (CH(CH3)2), 22.9 (ArMe), 21.3 (ArMe), 19.5
(CH(CH3)2), 10.6 (C5Me5). 31P{1H} NMR (C6D5Br, 163.0 MHz): δ
68.9. 29Si NMR (C6D5Br, 99.4 MHz): δ 278.9. 19F{1H} NMR (C6D5Br,
376.5 MHz): δ −132.3, −162.9, −166.6. Anal. Calcd for
C58H62BF20PRuSi: C, 53.18; H, 4.77. Found: C, 53.33; H, 4.77.
[Cp*(PiPr3)Ru(H)2(Si(CH2CH2Ph)Mes)][B(C6F)4] (5). By a
procedure analogous to that for 3, complex 5 was obtained as a bright
[Cp*(PiPr3)Ru(H)2(Si(OCHPh2)Mes)][B(C6F)4] (9). A solution of
benzophenone (0.008 g, 0.04 mmol) in C6H5F was added to a solution
of 1 (0.050 g, 0.04 mmol) in 1 mL of C6H5F to give a yellow solution.
After 5 min, the reaction mixture was dried under vacuum. The resulting
oil was washed with 3 aliquots of hexanes (ca. 10 mL) and then dried
1
under vacuum to give a light brown solid in 96% yield (0.055 g). H
NMR (C6D5Br, 600 MHz): δ 7.36 (5H, m, PhH), 7.22 (5H, m, PhH),
6.92 (2H, s, ArH), 5.85 (1H, s, OCH), 2.38 (3H, s, ArCH3), 2.35 (6H, s,
ArCH3), 2.09 (3H, br s, CH(CH3)2), 1.60 (15H, s, C5Me5), 1.04 (18H,
m, CH(CH3)2), −11.18 (2H, d, 2JPH = 19.6 Hz, 2JSiH = 38.3 Hz, RuH).
13C{1H} NMR (C6D5Br, 150.9 MHz): 149.6 (ArC), 148.1 (ArC), 143.4
(ArC), 140.8 (ArC), 139.9 (ArC), 139.5 (ArC), 137.9 (ArC), 137.6
(ArC), 135.9 (ArC), 132.3 (ArC), 128.9 (ArC), 128.4 (ArC), 99.6
(C5Me5), 83.9 (OCH), 26.9 (CH(CH3)2), 26.8 (CH(CH3)2), 22.8
(ArMe), 22.7 (ArMe), 21.5 (ArMe), 19.1 (CH(CH3)2), 10.6 (C5Me5).
31P{1H} NMR (C6D5Br, 163.0 MHz): δ 70.7. 29Si NMR (C6D5Br, 99.4
MHz): δ 204.4. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.3,
−162.9, −166.6. Anal. Calcd for C65H60BF20OPRuSi·3(C6H5F): C,
58.82; H, 4.46. Found: C, 58.77; H, 4.46.
1
yellow solid in 89% yield (0.048 g). H NMR (C6D5Br, 600 MHz): δ
7.30 (2H, m, PhH), 7.07 (2H, m, PhH), 6.96 (2H, s, ArH), 6.95 (1H, m,
PhH), 2.63 (2H, m, CH2), 2.41 (3H, s, ArCH3), 2.36 (6H, s, ArCH3),
2.05 (3H, br s, CH(CH3)2), 1.87 (2H, m, CH2), 1.54 (15H, s, C5Me5),
1.12 (18H, dd, J = 6.9 Hz, JPH = 15.0 Hz, CH(CH3)2), −11.61 (2H, d,
2JPH = 15.7 Hz, RuH). 13C{1H} NMR (C6D5Br, 150.9 MHz): 149.6
(ArC), 148.1 (ArC), 142.5 (ArC), 141.4 (ArC), 139.4 (ArC), 138.9
(ArC), 137.7 (ArC), 137.2 (ArC), 135.9 (ArC), 128.7 (ArC), 128.0
(ArC), 127.7 (ArC), 98.4 (C5Me5), 34.9 (CH2), 31.9 (CH2), 27.5
(CH(CH3)2), 27.4 (CH(CH3)2), 23.0 (ArMe), 22.8 (ArMe), 21.5
(ArMe), 19.4 (CH(CH3)2), 10.7 (C5Me5). 31P{1H} NMR (C6D5Br,
163.0 MHz): δ 69.1. 29Si NMR (C6D5Br, 99.4 MHz): δ 277.6. 19F{1H}
NMR (C6D5Br, 376.5 MHz): δ −132.3, −162.8, −166.6. Anal. Calcd for
C60H58BF20PRuSi·1/2(C6H5F): C, 54.91; H, 4.43. Found: C, 55.16; H,
4.59.
[Cp*(PiPr3)Ru(H)2(Si(OCHPhMe)Mes)][B(C6F)4] (10). By a
procedure analogous to that for 3, complex 4 was obtained as a pale
1
yellow-green solid in 78% yield (0.043 g). H NMR (C6D5Br, 600
MHz): δ 7.37 (3H, m, PhH), 6.99 (1H, s, ArH), 6.96 (2H, m, PhH), 6.91
(1H, s, ArH), 4.81 (1H, q, J = 6.6 Hz, OCH), 2.61 (3H, s, ArCH3), 2.40
(3H, s, ArCH3), 2.17 (3H, br s, CH(CH3)2), 2.11 (3H, s, ArCH3), 1.59
(15H, s, C5Me5), 1.46 (3H, d, J = 6.6 Hz, OCHMe), 1.14 (9H, m,
CH(CH3)2), 1.05 (9H, m, CH(CH3)2), −11.27 (1H, d, 2JPH = 18.9 Hz,
2JSiH = 41.7 Hz, RuH), −11.49 (1H, d, 2JPH = 18.7 Hz, 2JSiH = 41.7 Hz,
RuH). 13C{1H} NMR (C6D5Br, 150.9 MHz): 149.3 (ArC), 147.7
(ArC), 143.0 (ArC), 141.2 (ArC), 139.7 (ArC), 139.1 (ArC), 138.8
(ArC), 137.3 (ArC), 135.6 (ArC), 98.9 (C5Me5), 78.4 (OCH), 31.5
(OCHMe), 26.6 (CH(CH3)2), 26.5 (CH(CH3)2), 24.0 (ArMe), 22.7
(ArMe), 21.2 (ArMe), 18.8 (CH(CH3)2), 10.3 (C5Me5). 31P{1H} NMR
(C6D5Br, 163.0 MHz): δ 70.3. 29Si NMR (C6D5Br, 99.4 MHz): δ 199.7.
19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.3, −162.9, −166.6. Anal.
Calcd for C60H58BF20OPRuSi: C, 53.54; H, 4.34. Found: C, 53.30; H,
4.04.
[Cp*(PiPr3)Ru(H)2(Si(C5H9)Mes)][B(C6F)4] (6). By a procedure
analogous to that for 3, complex 5 was obtained as a bright yellow solid
1
in 85% yield (0.045 g). H NMR (C6D5Br, 600 MHz): δ 6.95 (2H, s,
ArH), 2.43 (6H, s, ArCH3), 2.37 (3H, s, ArCH3), 2.11 (3H, br s,
CH(CH3)2), 1.88 (4H, m, C5H9), 1.52 (15H, s, C5Me5), 1.47 (2H, m,
C5H9), 1.28 (3H, m, C5H9), 1.14 (18H, dd, J = 6.9 Hz, JPH = 13.7 Hz,
2
CH(CH3)2), −11.64 (2H, d, JPH = 14.7 Hz, RuH). 13C{1H} NMR
(C6D5Br, 150.9 MHz): 149.6 (ArC), 148.0 (ArC), 142.1 (ArC), 139.6
(ArC), 139.4 (ArC), 137.6 (ArC), 136.0 (ArC), 129.0 (ArC), 97.7
(C5Me5), 29.1 (C5H9), 27.6 (CH(CH3)2), 27.4 (CH(CH3)2), 25.9
(C5H9), 23.7 (ArMe), 23.0 (ArMe), 21.4 (C5H9), 19.6 (CH(CH3)2),
10.6 (C5Me5). 31P{1H} NMR (C6D5Br, 163.0 MHz): δ 68.1. 29Si NMR
(C6D5Br, 99.4 MHz): δ 215.0. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ
−132.2, −162.8, −166.6. Anal. Calcd for C57H58BF20PRuSi: C, 52.91; H,
4.52. Found: C, 53.30; H, 4.62.
[Cp*(PiPr3)Ru(H)2(Si(Mes){κ2-O(CH)(NPh)}][B(C6F5)4] (11). An
excess of phenylisocyanate (3 drops) was added to a solution of 1
(0.050 g, 0.04 mmol) in 1 mL of C6H5F to give a bright yellow solution.
After 1 h, the reaction mixture was dried under vacuum. The resulting oil
was washed with 3 aliquots of hexanes (ca. 10 mL) and then dried under
[Cp*(PiPr3)Ru(H)2(Si(CMeCHMe)Mes)][B(C6F)4] (7). By a
procedure analogous to that for 3, complex 7 was obtained as a golden
1
yellow solid in 90% yield (0.047 g). H NMR (C6D5Br, 600 MHz): δ
6.91 (2H, s, ArH), 6.47 (1H, quartet, CHMe), 2.39 (6H, s, ArCH3), 2.36
(3H, s, ArCH3), 1.92 (3H, quartet, J = 6.7 Hz, CH(CH3)2), 1.76 (3H, d,
J = 6.6 Hz, CHMe), 1.68 (3H, s, SiCMe), 1.64 (15H, s, C5Me5), 1.06
1
vacuum to give a light yellow solid in 85% yield (0.047 g). H NMR
(C6D5Br, 600 MHz): δ 8.14 (1H, s, OCH), 7.41 (2H, t, J = 7.1 Hz,
NPhH), 7.34 (1H, t, J = 7.1 Hz, NPhH), 7.02 (2H, d, J = 7.1 Hz, NPhH),
6.87 (2H, s, ArH), 2.48 (6H, br s, ArCH3), 2.31 (3H, s, ArCH3), 1.93
(15H, s, C5Me5), 1.73 (3H, m, CH(CH3)2), 1.04 (18H, m, CH(CH3)2),
−11.41 (1H, d, 2JPH = 24.4 Hz, RuH), −11.59 (1H, d, 2JPH = 22.6 Hz,
RuH). 13C{1H} NMR (C6D5Br, 150.9 MHz): 165.8 (OCHN), 149.7
(ArC), 148.1 (ArC), 142.6 (ArC), 142.4 (ArC), 141.0 (ArC), 139.5
(ArC), 138.6 (ArC), 137.6 (ArC), 135.9 (ArC), 135.0 (ArC), 98.2
(C5Me5), 28.1 (CH(CH3)2), 27.9 (CH(CH3)2), 23.0 (ArMe), 21.1
(ArMe), 19.5 (CH(CH3)2), 19.2 (CH(CH3)2), 11.4 (C5Me5). 31P{1H}
NMR (C6D6, 163.0 MHz): δ 76.0. 29Si NMR (C6D5Br, 99.4 MHz): δ
(18H, dd, J = 6.7 Hz, JPH = 14.2 Hz, CH(CH3)2), −11.02 (2H, d, 2JPH
=
20.3 Hz, 2JSiH = 14.1 Hz, RuH). 13C{1H} NMR (C6D5Br, 150.9 MHz):
149.7 (ArC), 148.0 (ArC), 146.3 (CMe), 145.3 (CMe), 142.4 (ArC),
139.3 (ArC), 137.6 (ArC), 136.8 (ArC), 136.6 (ArC), 99.4 (C5Me5),
27.7 (CH(CH3)2), 27.5 (CH(CH3)2), 23.9 (ArMe), 21.4 (ArMe), 19.3
(CH(CH3)2), 14.8 (CMe), 14.4 (CMe), 10.9 (C5Me5). 31P{1H} NMR
(C6D5Br, 163.0 MHz): δ 71.1. 29Si NMR (C6D5Br, 99.4 MHz): δ 301.4.
19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.3, −162.9, −166.6. Anal.
Calcd for C56H56BF20PRuSi: C, 52.55; H, 4.41. Found: C, 52.25; H,
4.51.
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71.7. 19F{1H} NMR (C6D6, 376.5 MHz): δ −132.3, −162.8, −166.6.
Anal. Calcd for C59H55BF20NOPRuSi: C, 52.69; H, 4.12; N, 1.04.
Found: C, 52.48; H, 3.76; N, 1.02.
27.6 (CH(CH3)2), 19.5 (CH(CH3)22), 11.0 (C5Me5). 31P{1H} NMR
(C6D5Br, 163.0 MHz): δ 78.0. 29Si NMR (C6D5Br, 99.4 MHz): δ 80.2.
19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.4, −162.7, −166.5. Anal.
Calcd for C62H55BF20NOPRuSi: C, 53.92; H, 4.01; N, 1.01. Found: C,
53.36; H, 3.94; 1.02.
[Cp*(PiPr3)Ru(H)2(Si(Mes){κ2-O(CH)(NPhCF3)})][B(C6F5)4] (12).
By a procedure analogous to that for 11, complex 12 was obtained as a
light brown solid in 88% yield (0.051 g). 1H NMR (C6D5Br, 600 MHz):
δ 8.31 (1H, s, OCH), 7.40 (2H, d, J = 7.9 Hz, NPhH), 6.93 (2H, s, ArH),
6.87 (2H, d, J = 7.9 Hz, NPhH), 2.48 (6H, br s, ArCH3), 2.36 (3H, s,
ArCH3), 1.92 (18H, s, C5Me5 + CH(CH3)2), 1.01 (18H, m,
CH(CH3)2), −11.33 (1H, d, 2JPH = 23.3 Hz, RuH), −11.48 (1H, br s,
RuH). 13C{1H} NMR (C6D5Br, 150.9 MHz): 166.2 (OCHN), 149.5
(ArC), 147.9 (ArC), 142.3 (ArC), 139.4 (ArC), 137.5 (ArC), 136.9
(ArC), 135.8 (ArC), 127.1 (ArC), 98.4 (C5Me5), 27.8 (CH(CH3)2),
23.8 (ArMe),22.9 (ArMe), 21.0 (ArMe), 19.3 (CH(CH3)2), 19.0
(CH(CH3)2), 11.3 (C5Me5). 31P{1H} NMR (C6D6, 163.0 MHz): δ
75.8. 29Si NMR (C6D5Br, 99.4 MHz): δ 75.8. 19F{1H} NMR (C6D6,
376.5 MHz): δ −62.4, −62.5, −63.5, −132.4, −162.8, −166.7. Anal.
Calcd for C60H54BF23NOPRuSi: C, 51.00; H, 3.85; N, 0.99. Found: C,
50.63; H, 3.91; N, 1.33.
[Cp*(PiPr3)Ru(H)2(SiPh2·NHMePh)][B(C6F)4] (16). An excess of
N-methylaniline (3 drops) was added to a solution of 1 (0.050 g, 0.04
mmol) in 1 mL of C6H5F to give a yellow solution. After 10 min, the
reaction mixture was dried under vacuum. The resulting oil was washed
with 3 aliquots of hexanes (ca. 10 mL) and then dried under vacuum to
give a white solid in 87% yield (0.047 g). 1H NMR (C6D5Br, 600 MHz):
δ 7.71 (4H, m, PhH), 7.45 (2H, m, PhH), 7.40 (4H, m, PhH), 7.22 (2H,
m, ArH), 7.06 (1H, m, ArH), 6.58 (2H, m, ArH), 4.37 (1H, s, NH), 2.94
(3H, s, NMe), 1.77 (15H, s, C5Me5), 1.66 (3H, m, PCH(CH3)2), 1.05
(18H, m, CH(CH3)2), −11.14 (2H, d, 2JPH = 24.2 Hz, RuH). 13C{1H}
NMR (C6D5Br, 150.9 MHz): 149.7 (ArC), 148.1 (ArC), 139.5 (ArC),
137.6 (ArC), 136.9 (ArC), 135.9 (ArC), 127.8 (ArC), 97.7 (C5Me5),
35.0 (NMe), 27.3 (CH(CH3)2), 27.2 (CH(CH3)2), 19.5 (CH(CH3)2),
11.4 (C5Me5). 31P{1H} NMR (C6D5Br, 163.0 MHz): δ 76.7. 29Si NMR
(C6D5Br, 99.4 MHz): δ 55.7. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ
−132.3, −162.8, −166.6. Anal. Calcd for C62H57BF20NPRuSi: C, 54.47;
H, 4.20; N, 1.02. Found: C, 54.38; H, 4.20; N, 1.35.
[Cp*(PiPr3)Ru(H)2(SiPh2·DMAP)][B(C6F)4] (13). A solution of
DMAP (0.005 g, 0.04 mmol) in C6H5F was added to a solution of 1
(0.050 g, 0.04 mmol) in 1 mL of C6H5F to give a colorless solution.
Immediately, the reaction mixture was dried under vacuum. The
resulting oil was washed with 3 aliquots of hexanes (ca. 10 mL) and then
dried under vacuum to give an off-white solid in 82% yield (0.045 g). 1H
NMR (C6D5Br, 600 MHz): δ 8.32 (2H, m, ArH), 7.64 (4H, m, PhH),
7.40 (6H, m, PhH), 6.31 (2H, m, ArH), 2.70 (3H, s, NMe), 2.66 (3H, s,
NMe), 1.59 (18H, s, C5Me5 + PCH(CH3)2), 1.05 (18H, dd, J = 6.9 Hz,
[Cp*(PiPr3)Ru(H)2(SiHMes·NHMePh)][B(C6F)4] (17). By a proce-
dure analogous to that for 3, complex 17 was obtained as an off-white
solid in 91% yield (0.049 g). 1H NMR (C6D5Br, 600 MHz): δ 7.29 (2H,
t, J = 7.8 Hz, PhH), 6.89 (3H, s, PhH), 6.87 (2H, s, ArH), 6.16 (1H, br s,
SiH), 5.17 (1H, br s, NH), 3.12 (3H, s, NCH3), 2.50 (6H, s, ArCH3),
2.34 (3H, s, ArCH3), 1.68 (18H, br s, C5Me5 + CH(CH3)2), 0.95 (18H,
br m, CH(CH3)2), −12.16 (2H, br s, RuH). 13C{1H} NMR (C6D5Br,
150.9 MHz): 149.3 (ArC), 147.6 (ArC), 144.5 (ArC), 142.0 (ArC),
139.0 (ArC), 137.3 (ArC), 135.6 (ArC), 97.0 (C5Me5), 34.7 (NMe), 27.6
(CH(CH3)2), 22.7 (ArMe), 20.8 (ArMe), 19.0 (CH(CH3)2), 10.7
(C5Me5). 31P{1H} NMR (C6D5Br, 163.0 MHz): δ 76.6. 29Si NMR
(C6D5Br, 99.4 MHz): δ 35.7. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ
−132.7, −163.1, −166.9. Anal. Calcd for C59H59BF20NPRuSi: C, 53.16;
H, 4.46; N, 1.05. Found: C, 53.38; H, 4.25; N, 1.35.
2
JPH = 13.0 Hz, CH(CH3)2), −11.92 (2H, d, JPH = 27.0 Hz, RuH).
13C{1H} NMR (C6D5Br, 150.9 MHz): 156.1 (ArC), 149.6 (ArC), 148.0
(ArC), 141.9 (ArC), 139.4 (ArC), 137.7 (ArC), 135.9 (ArC), 134.9
(ArC), 127.9 (ArC), 105.8 (ArC), 97.1 (C5Me5), 39.0 (NMe), 38.8
(NMe), 27.6 (CH(CH3)2), 19.8 (CH(CH3)2), 10.9 (C5Me5). 31P{1H}
NMR (C6D5Br, 163.0 MHz): δ 77.4. 29Si NMR (C6D5Br, 99.4 MHz): δ
68.5. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.3, −162.8, −166.5.
Anal. Calcd for C62H58BF20N2PRuSi: C, 53.88; H, 4.23; N, 2.03. Found:
C, 54.27; H, 4.07; N, 1.94.
[Cp*(PiPr3)Ru(H)2(SiPh2·tBuSONH2)][B(C6F)4] (18). A solution of
2-methylpropane-2-sulfinamide (0.006 g, 0.04 mmol) in C6H5F was
added to a solution of 1 (0.050 g, 0.04 mmol) in 1 mL of C6H5F to give a
pale yellow solution. After 10 min, the reaction mixture was dried under
vacuum. The resulting oil was washed with 3 aliquots of hexanes (ca. 10
mL) and then dried under vacuum to give an off-white solid in 89% yield
[Cp*(PiPr3)Ru(H)2(SiPh2·Ph2CO)][B(C6F)4] (14). A solution of
benzophenone (0.008 g, 0.04 mmol) in C6H5F was added to a solution
of 1 (0.050 g, 0.04 mmol) in 1 mL of C6H5F to give an orange solution.
After 15 min, the reaction mixture was dried under vacuum. The
resulting oil was washed with 3 aliquots of hexanes (ca. 10 mL) and then
dried under vacuum to give an orange solid in 87% yield (0.050 g). 1H
NMR (C6D5Br, 600 MHz): δ 7.92 (8H, d, J = 7.3 Hz, PhH), 7.56 (4H, t,
J = 7.3 Hz, PhH), 7.36 (8H, d, J = 7.3 Hz, PhH), 1.68 (18H, s, C5Me5 +
PCH(CH3)2), 1.08 (18H, dd, J = 6.9 Hz, JPH = 13.4 Hz, CH(CH3)2),
−11.06 (2H, d, 2JPH = 25.1 Hz, RuH). 13C{1H} NMR (C6D5Br, 150.9
MHz): 201.9 (OCPh2), 149.6 (ArC), 148.0 (ArC), 137.6 (ArC), 135.9
(ArC), 135.8 (ArC), 135.2 (ArC), 132.2 (ArC), 128.6 (ArC), 128.5
(ArC), 127.8 (ArC), 97.5 (C5Me5), 28.0 (CH(CH3)2), 27.9 (CH-
(CH3)2), 19.7 (CH(CH3)22), 11.1 (C5Me5). 31P{1H} NMR (C6D5Br,
163.0 MHz): δ 78.1. 29Si NMR (C6D5Br, 99.4 MHz): δ 78.3. 19F{1H}
NMR (C6D5Br, 376.5 MHz): δ −132.3, −162.8, −166.6. Anal. Calcd for
C68H58BF20PRuSi: C, 56.63; H, 4.05. Found: C, 56.88; H, 4.01.
[Cp*(PiPr3)Ru(H)2(SiPh2·PhCONH2)][B(C6F)4] (15). A solution of
benzamide (0.005 g, 0.04 mmol) in C6H5F was added to a solution of 1
(0.050 g, 0.04 mmol) in 1 mL of C6H5F to give a colorless solution.
Immediately, the reaction mixture was dried under vacuum. The
resulting oil was washed with 3 aliquots of hexanes (ca. 10 mL) and then
dried under vacuum to give an off-white solid in 93% yield (0.051 g). 1H
NMR (C6D5Br, 600 MHz): δ 7.97 (4H, d, J = 7.1 Hz, PhH), 7.84 (1H, d,
J = 7.6 Hz, ArH), 7.66 (2H, d, J = 7.6 Hz, ArH), 7.51 (4H, t, J = 7.1 Hz,
PhH), 7.45 (2H, d, J = 7.1 Hz, PhH), 7.34 (4H, t, J = 7.6 Hz, ArH), 5.90
(1H, br s, NH), 5.62 (1H, s, NH), 1.64 (15H, s, C5Me5), 1.41 (3H, sept, J
= 7.1 Hz, PCH(CH3)2), 1.07 (18H, dd, J = 7.1 Hz, JPH = 13.3 Hz,
1
(0.049 g). H NMR (C6D5Br, 600 MHz): δ 8.18 (4H, t, J = 7.4 Hz,
PhH), 7.64 (4H, m, PhH), 7.57 (2H, m, PhH), 4.38 (2H, s, NH2), 2.05
(3H, m, PCH(CH3)2), 1.56 (15H, s, C5Me5), 1.27 (9H, dd, J = 6.5 Hz,
JPH = 13.1 Hz, CH(CH3)2), 1.22 (9H, dd, J = 7.1 Hz, JPH = 13.0 Hz,
CH(CH3)2), −11.04 (1H, d, 2JPH = 27.6 Hz, RuH), −11.23 (1H, d, 2JPH
= 26.5 Hz, RuH). 13C{1H} NMR (C6D5Br, 150.9 MHz): 149.7 (ArC),
148.0 (ArC), 141.5 (ArC), 140.3 (ArC), 139.5 (ArC), 137.6 (ArC),
136.6 (ArC), 136.3 (ArC), 136.0 (ArC), 128.5 (ArC), 128.2 (ArC), 96.5
(C5Me5), 59.9 (C(CH3)3), 27.9 (CH(CH3)2), 22.1 (C(CH3)3), 19.7
(CH(CH3)2), 19.4 (CH(CH3)2), 10.7 (C5Me5). 31P{1H} NMR
(C6D5Br, 163.0 MHz): δ 79.3. 29Si NMR (C6D5Br, 99.4 MHz): δ
89.6. 19F{1H} NMR (C6D5Br, 376.5 MHz): δ −132.3, −162.7, −166.5.
Anal. Calcd for C59H59BF20PRuSi: C, 51.31; H, 4.31; N, 1.01. Found: C,
51.19; H, 4.67; N, 1.39.
AUTHOR INFORMATION
Notes
The authors declare no competing financial interest.
■
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■
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