Synthesis and reactivity of coordinatively unsaturated dinuclear ruthenium bridging imido complexes

Article abstract of DOI:10.1021/om1011227

[Cp*Ru(μ-NHPh)]₂ (Cp* = η⁵-C ₅Me₅) reacted with CO, t-BuNC, Ph₂S=CH ₂, or Me₃SiC=CH to give the dinuclear ruthenium bridging imido complexes [(Cp*Ru)₂(μ-NPh)(μ-L)] (2a, L = CO; 2b, L = t-BuNC; 2c, L = CH₂; 2d, L = CCHSiMe₃). Protonolysis of 2d with t-BuOH produced the parent vinylidene complex [(Cp*Ru) ₂(μ-NPh)(μ-CCH₂)] (2e). Treatment of 2e with HOTf or MeOTf afforded the cationic alkylidyne complexes [(Cp*Ru) ₂(μ-NPh)(μ-CR)]OTf (2f, R = Me; 2g, R = Et). Hydride abstraction from 2c with Ph₃CBF₄ gave the methylidyne complex [(Cp*Ru)₂(μ-NPh)(μ-CH)]BF₄ (2h). X-ray structures of 2a-c and 2f revealed short Ru-N distances (1.876-1.894 A) consistent with Ru-N multiple bonds, and the μ-alkylidyne 2f also featured short Ru-C bonds (1.929(7) and 1.914(7) A). In addition to giving simple Lewis base adducts such as [(Cp*Ru)₂(μ-NPh)(μ-CO) (PMe₃)] and [(Cp*Ru)₂(μ-NPh)(μ-CH ₂)(t-BuNC)₂], these imido complexes provided an array of novel ligand coupling reactions. Thus, 2b underwent a tandem imido-isocyanide coupling and C-H activation reaction to give an amidinate complex. Complexes 2c and 2e mediated imido-CO-methylene and imido-CO-vinylidene coupling to give [{Cp*Ru(CO)₂}₂(μ-PhNCOCH₂)] (6) and [{Cp*Ru(CO)}₂(μ-PhNCOC=CH₂)] (7), respectively. Complex 2c also underwent a selective coupling reaction with 2 equiv of Me ₃SiC=CH to give the μ-allenylimine complex [(Cp*Ru) ₂{μ-Me₃SiCH=C=C(SiMe₃)C(Me)=NPh}] (8). The imido methylidyne complex coupled with 2 equiv of alkynes to give [(Cp*Ru)₂{μ-HC(R¹CCR²)(R ²CCR¹)NPh}]OTf (9a-c), a product of double alkyne cycloaddition to the Ru-N and Ru-C multiple bonds and C-C coupling of the resulting ruthena- and azaruthenacyclobutene moieties.

Full text of DOI:10.1021/om1011227

ARTICLE
pubs.acs.org/Organometallics
Synthesis and Reactivity of Coordinatively Unsaturated Dinuclear
Ruthenium Bridging Imido Complexes
Shin Takemoto,* Tomoharu Kobayashi, Takahiro Ito, Akira Inui, Kenji Karitani, Sayuri Katagiri,
Yusaku Masuhara, and Hiroyuki Matsuzaka*
Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai,
Osaka 599-8531, Japan
S Supporting Information
b
ABSTRACT: [Cp*Ru(μ-NHPh)]2 (Cp* = η5-C5Me5) reacted
with CO, t-BuNC, Ph2SdCH2, or Me3SiCtCH to give the
dinuclear ruthenium bridging imido complexes [(Cp*Ru)2(μ-
NPh)(μ-L)] (2a, L = CO; 2b, L = t-BuNC; 2c, L = CH2; 2d, L =
CCHSiMe3). Protonolysis of 2d with t-BuOH produced the
parentvinylidenecomplex [(Cp*Ru)2(μ-NPh)(μ-CCH2)] (2e).
Treatment of 2e with HOTf or MeOTf afforded the cationic
alkylidyne complexes [(Cp*Ru)2(μ-NPh)(μ-CR)]OTf (2f, R =
Me; 2g, R = Et). Hydride abstraction from 2c with Ph3CBF4 gave the methylidyne complex [(Cp*Ru)2(μ-NPh)(μ-CH)]BF4 (2h).
X-ray structures of 2aꢀc and 2f revealed short RuꢀN distances (1.876ꢀ1.894 Å) consistent with RuꢀN multiple bonds, and the μ-
alkylidyne 2f also featured short RuꢀC bonds (1.929(7) and 1.914(7) Å). In addition to giving simple Lewis base adducts such as
[(Cp*Ru)2(μ-NPh)(μ-CO)(PMe3)] and [(Cp*Ru)2(μ-NPh)(μ-CH2)(t-BuNC)2], these imido complexes provided an array of
novel ligand coupling reactions. Thus, 2b underwent a tandem imidoꢀisocyanide coupling and CꢀH activation reaction to give an
amidinate complex. Complexes 2c and 2e mediated imidoꢀCOꢀmethylene and imidoꢀCOꢀvinylidene coupling to give
[{Cp*Ru(CO)2}2(μ-PhNCOCH2)] (6) and [{Cp*Ru(CO)}2(μ-PhNCOCdCH2)] (7), respectively. Complex 2c also underwent
a selective coupling reaction with 2 equiv of Me3SiCtCH to give the μ-allenylimine complex [(Cp*Ru)2{μ-Me3SiCHdCdC-
(SiMe3)C(Me)dNPh}] (8). The imido methylidyne complex coupled with 2 equiv of alkynes to give [(Cp*Ru)2{μ-HC(R1CCR2)-
(R2CCR1)NPh}]OTf (9aꢀc), a product of double alkyne cycloaddition to the RuꢀN and RuꢀC multiple bonds and CꢀC coupling
of the resulting ruthena- and azaruthenacyclobutene moieties.
’ INTRODUCTION
dirhodium μ-imido complexes,29,36 CO diamination and redox-
coupled H2 activation on [Cp*Rh(μ-NTs)]2,37,38 catalytic carbo-
diimide formation via dinickel μ-imido complexes,39 and the use
of dicopper μ-imido complexes in catalytic CꢀH amination
reactions.35 Additionally, bridging imido complexes have also
received interest for their relevance to dinitrogen reduction42ꢀ44
and ammonia activation systems.45,46
In a previous communication, we described the reactions of the
diruthenium bridging amido complex [Cp*Ru(μ-NHPh)]2 (1)47
with several π-acceptor ligands (i.e., CO, t-BuNC, and CH2).29 In
contrast to the reaction of 1 with PMe3, which produces the
monomeric amido complex [Cp*Ru(NHPh)(PMe3)2],47 the
reactions of 1 with the above π-acceptor ligands produced the
dinuclear bridging imido complexes [(Cp*Ru)2(μ-NPh)(μ-L)]
(Scheme 1; 2a, L = CO; 2b, L = t-BuNC; 2c, L = CH2).29
Spectroscopic monitoring of the reaction of 1 with CO revealed
that the μ-CO adduct [(Cp*Ru)2(μ-NHPh)2(μ-CO)] (1a) is
rapidly generated upon addition of CO to 1 and cleanly converted
into 2a and aniline (Scheme 1), indicating that the imido complex
Transition metal imido complexes are an important class of
metalꢀnitrogen multiply bonded compounds1ꢀ8 that have found
many applications in organic synthesis, such as hydroamination of
alkynes,9,10 aziridination of olefins,11 and nitrene insertion into
CꢀH bonds.11,12 Transition metal imido complexes are also
widely used as catalysts for the metathesis13 and polymerization14
of olefins, where the MdNR multiple bond is an effective ancillary
unit that supports electron-deficient metal alkylidene and alkyl
species.
Recently, considerable attention has been focused on the
chemistry of dinuclear bridging imido complexes, which provide
unique dinuclear platforms with coordinatively unsaturated metal
centers and potentially reactive metalꢀnitrogen bonds.15ꢀ41 Early
studies by the Bergman and Sharp groups have demonstrated that
bridging imido complexes of low-oxidation-state late transition
metals display remarkable reactivity, such as the facile single and
double insertion of CO into metalꢀnitrogen bonds,23 transfer of a
μ-imido ligand to PMe3,24 and interconversion between μ-imido
and μ-oxo complexes.24 Recent efforts by us and others have
extended the scope of the imido reactivity in dinuclear systems,
such as the alkyne insertion reactions on diruthenium and
Received: November 30, 2010
Published: January 25, 2011
r
2011 American Chemical Society
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Scheme 1
Chart 1
2a was formed by bridging coordination of CO to the unsaturated
ruthenium centers in 1 followed by R-elimination of aniline from
the saturated adduct 1a.29 X-ray studies for 2aꢀc revealed short
RuꢀN (1.88ꢀ1.89 Å) distances consistent with the delocalized
multiple bond over the RuꢀNꢀRu linkage. The RuꢀRu dis-
tances are also short (2.57ꢀ2.66 Å), and DFT studies supported
the existence of a net RuꢀRu bonding character, although there is
uncertainty about actual RuꢀRu bond order because RuꢀRu
bonding and antibonding orbitals are not purely metal-centered
but delocalized into bridging ligand fragments.29 A plausible
resonance description for 2aꢀc is shown in Chart 1, which can
explain the delocalized RuꢀN multiple bonds, the existence of
RuꢀRu bonding interaction, and the unsaturated nature of the
ruthenium centers (18e and 16e in each structure).
Figure 1. ORTEP drawing of 2f, showing 35% thermal ellipsoids. The
triflate anion and hydrogen atoms are omitted. Selected bond lengths
(Å) and angles (deg): Ru1ꢀRu2 = 2.5319(8); Ru1ꢀN1 = 1.879(5);
Ru2ꢀN1 = 1.881(5); Ru1ꢀC1 = 1.929(7); Ru2ꢀC1 = 1.914(7);
C1ꢀC2 = 1.480(10); N1ꢀC3 = 1.421(8); Ru1ꢀN1ꢀRu2 = 84.7(2);
Ru1ꢀC1ꢀRu2 = 82.4(3); N1ꢀRu1ꢀC1 = 96.2(3); N1ꢀRu2ꢀC1 =
96.7(3); Ru1ꢀN1ꢀC3 = 140.1(4); Ru2ꢀN1ꢀC3 = 135.2(4);
Ru1ꢀC1ꢀC2 = 139.1(5); Ru2ꢀC1ꢀC2 = 138.5(5).
The imido complexes 2aꢀc constitute a new family of π-
stabilized 16-electron Cp*Ru complexes, whose chemistry has
received considerable attention.48ꢀ64 The key feature of the
imido complexes 2aꢀc is the assembly of potentially reactive
RuꢀN, RuꢀC, and RuꢀRu bonds on a coordinatively unsatu-
rated bimetallic site. We have investigated the reactivity of these
imido complexes, and two specific examples, namely, phosphine
PꢀH bond addition across the RuꢀN bond and heteronuclear
cluster formation with a Pt(0) fragment, have recently been
reported.32,34,40 In the present study we have synthesized a new
series of diruthenium imido complexes containing μ-vinylidene
and μ-alkylidyne functionalities, 2dꢀh. We have also investi-
gated the reactivity of the whole series of the imido complexes
2aꢀh toward unsaturated small molecules and revealed an array
of ligand coupling reactions that are unprecedented in transition
metal imido chemistry. Details of these findings are reported
herein.
The trimethylsilylvinylidene complex 2d was found to be
highly moisture sensitive. A trace of moisture caused hydrolysis
of 2d to give the parent vinylidene complex [(Cp*Ru)2(μ-
NPh)(μ-CdCH2)] (2e), probably via protonation at the viny-
lidene β carbon atom. For preparative purpose, complex 2e was
best prepared by the treatment of 2d with excess t-BuOH in
toluene (eq 2) and isolated in ca. 60% yield as a gray-violet
microcrystalline solid.
’ RESULTS AND DISCUSSION
Synthesis of the Imido Vinylidene and Imido Alkylidyne
Complexes 2dꢀh. We previously reported the reaction of 1
with diphenylacetylene, which gave [(Cp*Ru)2(μ-PhCCPh-
NPh)], a product of alkyne insertion into RuꢀN(imido)
bonds.29 As an extension of this study, we examined a reaction
of 1 with Me3SiCtCH (eq 1).64 Interestingly, the reaction
produced a new imido complex containing a μ-vinylidene ligand,
[(Cp*Ru)2(μ-NPh)(μ-CdCHSiMe3)] (2d), rather than the
expected alkyne insertion product. Complex 2d, isolated quanti-
tatively as a maroon solid, showed 13C NMR resonances
characteristic of the μ-vinylidene R and β carbons at 314.8 and
117.7 ppm, respectively.65
The facile protonolysis of the CꢀSi bond in 2d suggested that
the μ-vinylidene ligands in these imido complexes could be
protonated at the vinylidene β carbon atom. This was partly
supported by an H/D exchange reaction between 2e and excess
D2O in benzene-d6, which caused the disappearance of the
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Table 1. Selected Bond Distances (Å) in 2a, 2b, 2c, and 2f
2a
2b
2c
2f
Ru1ꢀRu2
Ru1ꢀN1
Ru2ꢀN1
Ru1ꢀC1
Ru2ꢀC1
N1ꢀC3
2.6013(4)
1.876(6)
1.880(6)
2.002(8)
1.993(8)
1.423(9)
2.6594(5)
1.890(4)
1.885(4)
2.090(5)
2.082(5)
1.402(7)
2.5728(11)
1.891(5)
1.894(5)
2.057(6)
2.061(6)
1.415(7)
2.5319(8)
1.879(5)
1.881(5)
1.929(7)
1.914(7)
1.421(8)
μ-vinylidene 1H NMR signal (δ 6.55), suggesting the formation
of [(Cp*Ru)2(μ-NPh)(μ-CdCD2)] (2e-d2). Most significantly,
we were able to isolate the cationic imido alkylidyne complex
[(Cp*Ru)2(μ-NPh)(μ-CMe)]OTf (2f) in 93% yield by proton-
ation of 2e with HOTf (eq 3). Although protonation of
a μ-vinylidene ligand is an established organometallic reaction,65
it is rather surprising that this occurs in preference to protona-
tion at imido nitrogen. Probably, π-donation from the imido
ligand would play an important role in the stability of complex
2f. The X-ray structure and bonding of 2f are discussed in a
later section. The 13C NMR spectrum of 2f showed a signal
attributable to the alkylidyne R carbon at 384.4 ppm. The
propylidyne analogue [(Cp*Ru)2(μ-NPh)(μ-CEt)]OTf (2g)
was also prepared in 94% yield by alkylation of 2e with MeOTf
(eq 3).
Figure 2. Selected molecular orbitals of [(CpRu)2(μ-NH)(μ-CH)]þ
with their energy (eV) and prevalent bonding character.
similar to those in 2aꢀc. The μ-imido and μ-ethylidyne ligands
are both trigonal planar (angle sums 360°) and exhibit short
RuꢀN (1.879(5) and 1.881(5) Å) and RuꢀC (1.929(7) and
1.914(7) Å) distances indicative of RuꢀN and RuꢀC multiple
bonds delocalized over the Ru2N and Ru2C units, respectively.
The RuꢀN distances are similar to those in 2aꢀc,29 and the
RuꢀCalkylidyne distances are comparable to those in [Cp*Ru(μ-
CMe)2OsCp*].67 The RuꢀRu distance in 2f is 2.5319(8) Å,
which is the shortest among 2aꢀf.
The successful isolation of the cationic μ-alkylidyne complexes
2f and 2g prompted us to prepare a μ-methylidyne analogue by
hydride abstraction from the μ-methylene complex 2c, an
approach taken to synthesize [(CpFe)2(CO)3(μ-CH)]PF6 from
[(CpFe)2(CO)3(μ-CH2)].66 Thus treatment of 2c with 1 equiv
of Ph3CBF4 at low temperature cleanly afforded the brown
crystalline [(Cp*Ru)2(μ-NPh)(μ-CH)]BF4 (2h), isolated in
The nature of bonding in 2f was investigated by DFT calcula-
tions. The structure optimization was performed for the simpli-
fied model [(CpRu)2(μ-NH)(μ-CH)]þ and for the full molecule
[(Cp*Ru)2(μ-NPh)(μ-CMe)]þ. The former was used for quali-
tative evaluation of bonding in the central Ru2NC core. The
relevant molecular orbitals are presented in Figure 2. The MO58
(HOMO) and MO57 can be characterized as δ-type RuꢀRu
antibonding and bonding interactions, respectively.68 The MO56
and MO50 represent another pair of RuꢀRu δ antibonding and
bonding combinations. The MO50 also displays π-bonding
interactions in both RuꢀNꢀRu and RuꢀCꢀRu linkages, in-
dicating the π-conjugated nature of the RuꢀN and RuꢀC
multiple bonds. The MO52 and MO49 can be viewed as the
RuꢀRu σ-bonding and σ-antibonding orbitals, respectively. The
latter has a significant contribution from the methylidyne 2p
orbital and hence has a diminished RuꢀRu σ-antibonding
character. The MO48 shows a π-type interaction within the
Ru2N moiety with a considerable RuꢀRu π-bonding cha-
racter. These seven occupied orbitals constitute a formal
π2σ*2δ2σ2δ*2δ2δ*2 configuration with respect to the RuꢀRu
bond. Although these orbitals are not purely metal-centered, a net
RuꢀRu bonding character would be produced by the π-bonding
MO that spreads over the Ru2N unit (MO48) and the diminished
RuꢀRu σ-antibonding character in MO49, which leaves a net
RuꢀRu σ-bonding interaction.
1
70% yield after recrystallization from THF (eq 4). The H
NMR spectrum of 2h contained a resonance for the μ-CH proton
at 18.15 ppm. The 13C NMR signal for the μ-CH carbon in 2h was
observed at 377.1 ppm. Although these μ-CH resonances are not
as deshielded as those of [(CpFe)2(CO)3(μ-CH)]PF6 (δH 22.8,
δC 490.2),66 they are easily distinguished from the μ-CH2
resonances of 2c (δH 12.79, δC 186.6).
Structure and Bonding of the Imido Alkylidyne Complex
2f. The X-ray structure of 2f is shown in Figure 1. Selected bond
distances are listed in Table 1 with the corresponding distances in
2aꢀc. The imido alkylidyne 2f has a planar central Ru2NC core
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Table 2. DFT-Calculated RuꢀRu Distances (Å) and Bond
Orders (Mayer and Wiberg)a
2a
2b
2c
2f
RuꢀRu
Mayer
2.6293
0.5019
0.4744
2.6966
0.4699
0.4516
2.6024
0.5526
0.5090
2.5766
0.5539
0.5250
Wiberg
a Calculated for the full structures [(Cp*Ru)2(μ-NPh)(μ-L)] (L = CO,
t-BuNC, CH2, CMeþ).
We further consider the effect of the contribution of ligand-
based orbitals in MO50 and MO49 on the RuꢀRu bonding.
These MOs can be considered as representing the back-bonding
from the occupied RuꢀRu δ and σ* orbitals into the correspond-
ing empty 2p orbitals of the methylidyne ligand, CHþ. The back-
donation from the RuꢀRu σ* orbital would be more significant
than that from the RuꢀRu δ orbital, since the former is a RuꢀC
σ interaction while the latter is a RuꢀC π interaction. These
types of back-bonding interactions should exist in the whole
series of the imido complexes 2aꢀh, and the difference in the
extent of back-bonding would be reflected in the variation in
RuꢀRu distances. Indeed, the observed RuꢀRu distances in
2aꢀf become shorter (2b > 2a > 2c > 2f) as the acceptor strength
of the bridging carbon ligands increases (CNBut < CO < CH2 <
CMeþ). This also supports our view that back-bonding from the
filled RuꢀRu σ* orbital plays an important role in the formation
of the RuꢀRu bonding interaction.
Figure 3. ORTEP drawing of 3a, showing 35% thermal ellipsoids.
Hydrogen atoms are omitted. Selected bond lengths (Å) and angles
(deg): Ru1ꢀRu2 = 2.6696(6); Ru1ꢀN1 = 1.884(4); Ru2ꢀN1 =
2.056(4); Ru1ꢀC1 = 2.024(5); Ru2ꢀC1 = 1.997(6); Ru2ꢀP1 =
2.3012(18); N1ꢀC2 = 1.385(6); Ru1ꢀN1ꢀRu2 = 85.20(15);
Ru1ꢀC1ꢀRu2 = 83.2(2); N1ꢀRu1ꢀC1 = 95.5(2); N1ꢀRu2ꢀC1 =
91.17(19); Ru1ꢀN1ꢀC2 = 142.2(3); Ru2ꢀN1ꢀC2 = 132.2(3).
RuꢀN distance (2.056(4) Å) than the other (1.884(4) Å).
The latter short RuꢀN distance and the planarity of the imido
nitrogen (angle sum 359.6°) indicate the presence of π donation
from the imido nitrogen to the 16-electron Ru1. The RuꢀRu
distance of 2.6696(6) Å is consistent with a RuꢀRu single bond,
which is also expected from electron counting.
To further confirm the above trend in RuꢀRu distances, we
carried out full structure optimization for 2aꢀf and computed
bond orders (Mayer69 and Wiberg70 bond indices) for these
structures (Table 2). The calculated RuꢀRu distances well
reproduced the experimentally observed trend (2f < 2c < 2a <
2b), and the bond order indices are also consistent with this trend.
The relatively small bond order values are probably due to the
delocalization of RuꢀRu bonding electrons into ligand-centered
orbitals, which is often encountered in bridged dinuclear
systems.71ꢀ73
Although reactions of the imido complexes 2aꢀh with other
potential two-electron donors such as CO led mostly to ligand
coupling reactions (vide infra), treatment of the μ-methylene and
μ-vinylidene imido complexes 2c and 2e with excess t-BuNC
afforded the stable bis-isocyanide adducts [{Cp*Ru(t-BuNC)}2-
(μ-NPh)(μ-L)] (4c, L = CH2; 4e, L = CCH2; eq 6), which were
isolated in ca. 60% yield as dark yellow crystals. The infrared
spectra of 4c and 4e showed two isocyanide CtN stretching
bands at around 2100 and 2040 cmꢀ1. The 1H NMR spectra of
these complexes contained Cp* and t-Bu signals in 30:18
intensity ratio, and complex 4c displayed two diastereotopic μ-
methylene resonances at 8.56 and 7.77 ppm consistent with the
cis coordination of the two isocyanide ligands.
Reactivity of Imido Complexes 2aꢀh. Formation and
Structures of PMe3 and t-BuNC Adducts. The coordinatively
unsaturated nature of these imido complexes was exemplified by
their reaction with PMe3. Treatment of 2aꢀc with 2.5 equiv of
PMe3 in THF cleanly afforded the corresponding mono-PMe3
adducts [(Cp*Ru)2(μ-NPh)(μ-L)(PMe3)] (3a, L = CO; 3b, L =
1
t-BuNC; 3c, L = CH2) in ca. 60% yield (eq 5). The H NMR
spectra of these products in C6D6 contained two inequivalent
Cp* signals, one of which appeared as a doublet due to coupling
with the 31P nucleus (4JPH = 1.0ꢀ1.5 Hz).
The structures of 4c and 4e were determined by X-ray
crystallography. An ORTEP drawing of 4c is shown in Figure 4.
Most notable features are the pyramidal geometry at the imido
nitrogen (angle sum 334.3°) and the elongated RuꢀN bond
distances (2.050(2), 2.029(2) Å) compared to those in 2c
(1.893(av) Å). These features indicate that the RuꢀN multiple
bond is essentially absent in these complexes, and a nonbonding
pair of electrons is localized on the imido nitrogen atom. The
pyramidalization of imido nitrogen on going from 2c to 4c is
consistent with the theory of dπꢀpπ repulsion,74 demonstrating
that the achievement of an 18-electron configuration at both of
the two ruthenium centers considerably reduces the RuꢀN π-
bonding interaction and causes the localization of the imido lone
Complex 3a was structurally characterized by X-ray diffraction.
An ORTEP diagram is shown in Figure 3. The molecule features
unsymmetrical dinuclear structure with one PMe3, and the
phosphine-containing ruthenium (Ru2) has a much longer
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Figure 5. ORTEP drawing of an isomer of 5. Ellipsoids are drawn at the
35% probability level. Hydrogen atoms are omitted. Selected bond
lengths (Å): Ru1ꢀN1 = 2.157(3); Ru1ꢀN2 = 2.177(3); Ru1ꢀC12 =
1.901(4); Ru2ꢀC7 = 2.155(4); Ru2ꢀC17 = 1.914(5); Ru2ꢀC22 =
1.887(4); N1ꢀC1 = 1.326(5); N2ꢀC1 = 1.311(5).
Figure 4. ORTEP drawing of 4c, showing 35% thermal ellipsoids.
Hydrogen atoms are omitted. Selected bond lengths (Å) and angles
(deg): Ru1ꢀRu2 = 2.6760(3); Ru1ꢀN1 = 2.050(2); Ru2ꢀN1 =
2.029(2); Ru1ꢀC1 = 2.062(3); Ru2ꢀC1 = 2.066(3); Ru1ꢀC8 =
1.883(3); Ru2ꢀC9 = 1.880(3); N1ꢀC2 = 1.369(3); Ru1ꢀN1ꢀRu2
= 82.00(8); Ru1ꢀC1ꢀRu2 = 80.82(11); N1ꢀRu1ꢀC1 = 97.62(10);
N1ꢀRu2ꢀC1 = 98.14(10); Ru1ꢀN1ꢀC2 = 125.51(17); Ru2ꢀN1ꢀ
C2 = 126.80(18).
pair electrons on the nitrogen atom. Similar structural features
were also observed for 4e (see Supporting Information).
ImidoꢀCO Coupling Reactivity. CO is among the most
prevalent substrates in imido group transfer reactions.23,75ꢀ82
Treatment of the imido complex 2a with excess CO (1 atm)
in C6D6 at room temperature resulted in the formation of
[Cp*Ru(CO)2]2 (90%) and PhNCO (20%) (eq 7). These
1
Characterization of 5 was based on H NMR, FAB-MS, and
elemental analysis. The structure of one isomer was confirmed by
single-crystal X-ray diffraction (vide infra). The H NMR spec-
1
products were identified by H NMR and GC-MS analyses,
1
1
and yields were determined by integration of H NMR signals
trum of 5 contained signals attributable to the amidinate CH
protons at 9.97 (major isomer) and 8.95 (minor isomer) ppm.
Each isomer showed three t-Bu resonances in 1:1:2 intensity ratio,
which can be rationalized by assuming a rapid exchange of
diastereotopic t-BuNC ligands on the Cp*Ru(t-BuNC)2 frag-
ment. The FAB-MS spectrum of 5 showed a molecular ion peak at
m/z 897 and a series of fragment peaks at m/z 814, 731, and 648
due to the successive loss of t-BuNC ligands.
The solid sample of 5 contained some large crystals suitable for
X-ray study, which revealed the structure of one isomer of 5
(Figure 5). The orthometalated amidinate ligand is κ2-bonded to
the Cp*Ru(t-BuNC) fragment by the amidinate nitrogen atoms
and is η1-bonded to the Cp*Ru(t-BuNC)2 fragment with the
ortho phenyl carbon atom, C7. The RuꢀN and CꢀN bond
distances for the amidinate moiety are similar to those found in
[Cp*Ru(L)(amidinate)].59 The least-squares plane defined by
the amidinate moiety (i.e., Ru1, N1, C1, N2 atoms) is roughly
coplanar with the phenylene ring, and the two Cp* groups are
mutually cis with respect to this approximate plane. Restricted
rotation about the Ru2ꢀC7 bond is suggested by the steric
crowding around Ru2, which prevents interconversion between
the cis and trans isomers.
The imidoꢀisocyanide coupling usually gives carbodiimide
complexes.30,76,78 Sometimes, unusual multiple isocyanide inser-
tion and cyclometalation products are observed.26,84 As to the
reaction of 2b with t-BuNC, the structure of the product 5
suggests that the reaction involves imidoꢀisocyanide coupling,
phenyl CꢀH activation, and amidinate CꢀH bond formation. A
possible mechanism that includes these processes is shown in
Scheme 2. The initial step would be the coordination of
isocyanide molecules to give the saturated bis-isocyanide adduct
against an internal standard. Organic products other than phenyl
isocyanate were also observed by 1H NMR, but they could not be
identified. Although the yield of PhNCO was low, the above
results demonstrate the imido transfer ability of the diruthenium
complex 2a. The reaction probably proceeded via coordination
of CO to the 16-electron ruthenium centers in 2a. This would
give a bis-carbonyl adduct containing a pyramidal imido ligand
analogous to that observed in the bis-isocyanide adduct 4c. Such
a pyramidal imido ligand would be nucleophilic enough to attack
a coordinated CO to give a PhNCO ligand, which would be
released from the metal centers in the presence of excess CO.
Amidinate Formation via ImidoꢀIsocyanide Coupling.
Isocyanides are isoelectronic with CO, and we examined imi-
doꢀisocyanide coupling reactivity by using 2b. This complex
reacted with excess t-BuNC to give the orthometalated amidinate
complex [(Cp*Ru)2(μ-t-BuNCHNC6H4)(t-BuNC)3] (5), a
product of tandem imidoꢀisocyanide coupling and phenyl
CꢀH bond activation (eq 8). Complex 5 was produced as a
2:1 mixture of two stereoisomers that differ in the relative
orientation of the two Cp* groups. Recrystallization from hexane
afforded 5 as a yellow crystalline solid, which also contained the
two isomers in 2:1 molar ratio. The yield was typically 70%.
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Scheme 2
Figure 6. ORTEP drawing of 70, showing 35% thermal ellipsoids.
Hydrogen atoms are omitted. Selected bond lengths (Å) and angles
(deg): Ru1ꢀRu2 = 2.8521(5); Ru1ꢀN1 = 2.121(2); Ru1ꢀC1 =
2.036(3); Ru1ꢀC4 = 1.866(3); Ru2ꢀC1 = 2.104(3); Ru2ꢀC2 =
2.239(3); Ru2ꢀC5 = 1.853(3); C1ꢀC2 = 1.388(4); C1ꢀC3 = 1.497(4);
C3ꢀN1 = 1.349(4); C3ꢀO1 = 1.225(3); C2ꢀC1ꢀC3 = 130.4(3).
A, the formation of which was indirectly supported by the
isolation and characterization of 4c (vide infra). Then, imidoꢀ
isocyanide coupling would proceed via nucleophilic attack of
imido nitrogen on a coordinated isocyanide to give the μ-κ1:η1-
carbodiimide intermediate B. The next step would be the
rearrangement of B to the μ-κ2:η1-bonded complex C with an
amidinate-like four-membered metallacycle. Subsequent CꢀH
activation by the 16-electron Ru center could give D, which
would be followed by CꢀH reductive elimination and isocyanide
coordination to furnish the observed product 5.
ImidoꢀCOꢀMethylene and ImidoꢀCOꢀVinylidene Cou-
pling Reactions. The imido methylene complex 2c provided an
example of highly selective multiligand coupling reaction invol-
ving both the μ-imido and μ-methylene moieties. Thus, treat-
ment of 2c with excess CO (1 atm) in THF at room temperature
afforded the dinuclear acetanilido(2ꢀ) complex [{Cp*Ru-
(CO)2}2(μ-PhNCOCH2)] (6) in 73% yield as a result of
Formation of μ-Allenylimine Ligand via Imidoꢀ
AlkyneꢀMethylene Coupling. The reactivity of bridging imido
complexestowardalkynes has beenstudiedextensively.29,36,45,88,89
ImidoꢀCOꢀalkyne coupling reactions have been observed for
some imido carbonyl clusters,88,89 while direct imidoꢀalkyne
coupling is rare in bridging imido systems.29,36 We now found
that the imido methylene complex 2c undergoes a selective
multiligand coupling reaction with an alkyne. Thus, treatment of
2c with a slight excess of Me3SiCtCH (5 equiv) in THF at room
temperature afforded the product formulated as the μ-allenyli-
mine complex [(Cp*Ru)2{μ-Me3SiCHdCdC(SiMe3)C(Me)d
NPh}] (8) in88% yield (eq11). Thenewly formed ligandfeatured
an acyclic vinylideneꢀalkyneꢀimido linkage, with the central
alkyne unit {Me3SiCCMe} indicating a formal methylene inser-
1
imidoꢀCOꢀmethylene coupling (eq 9). The H NMR spec-
trum of 6 showed a singlet for the R-ketonyl proton at δ 2.13
ppm, similar to that in [{Cp*Ru(CO)2}2(μ-COCH2)] (2.41
ppm).85 The FAB-MS spectrum of 6 contained a molecular ion
peak at m/z 719 and a series of fragment peaks due to successive
loss of four CO ligands (m/z 691, 663, 635, 607).
1
tion into the alkyne CꢀH bond. The H NMR spectrum of 8
contained signals attributable to the terminal allenic proton (δ
4.22) and the imine methyl substituent (δ 1.99). The 13C NMR
spectrum of 8 showed the central allenic carbon resonance at
183.5 ppm, a shift indicative of considerable μ-carbenic character.
The imido vinylidene complex 2d also underwent coupling
reaction with CO (eq 10). The product, isolated in 69% yield as
red plates, was the μ-acrylanilido(2ꢀ) complex 7, which features
a novel imidoꢀCOꢀvinylidene coupling sequence. The pre-
1
sence of coordinated CdCH2 group was evident from the H
NMR signals at 4.07 and 4.01 ppm (d, 1H, J = 2.0 Hz). The 13C
NMR spectrum of 7 showed two terminal CO resonances at
220.5 and 207.3 ppm. The carbon resonances for the CdCH2
group at δ 48.8 (CH2) and 175 (quaternary) were consistent
with the μ-η1:η2-vinylic structure.86,87 The structure of 7
was further elucidated by X-ray analysis of the NAr ana-
logue [{Cp*Ru(CO)}2(μ-CH2dCCONAr)] (70, Ar = p-tolyl,
Figure 6). The compound contains a RuꢀRu single bond
(RuꢀRu = 2.8521(5) Å), which contrasts to the non me-
talꢀmetal bonded structure of 6. The μ-η1:η2 coordination of
the CdCH2 group is confirmed, and the amidato nitrogen atom
is terminally bound with a RuꢀN distance of 2.121(2) Å.
The X-ray structure of 8 is shown in Figure 7. The μ-
allenylimine ligand forms three- and five-membered metallacycles
with the Ru1 atom. The latter is almost planar and is η5-bonded to
Ru2. Considerable back-bonding to the μ-allenylimine ligand is
indicated by the bent C1ꢀC2ꢀC3 linkage (140.9(4)°) as well
as the bond lengths in the C1ꢀC2ꢀC3ꢀC4ꢀN1 chain
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Scheme 3
alkynes. The imido methylidyne complex 2h has both RuꢀN and
RuꢀC multiple bonds, and it is found that this integrated multiple-
bond system reacts with alkynes to give products of tandem double
alkyne cycloaddition and ruthenacyclobuteneꢀazaruthenacyclo-
butene coupling. Thus, heating a mixture of [(Cp*Ru)2(μ-NPh)-
(μ-CH)]OTf(2h0)91 and a 5-fold excess of p-tolylacetylene in THF
at 60 °C for 4 h produced the 6-phenyl-2,5-di(p-tolyl)-6-aza-1,3,5-
hexatrien-1-yl complex [(Cp*Ru)2(μ-HC(R1CCR2)(R2CCR1)-
NPh)]OTf (9a, R1 = p-tolyl, R2 = H) in 70% yield as reddish-
purple block crystals (eq 12). Complex 2h0 also reacted with
1-hexyne and diphenylacetylene under slightly forcing conditions
to give the corresponding products 9b (47%) and 9c (50%),
respectively. These products were characterized by elemental
analysis and NMR spectroscopy, and complexes 9a and 9b were
structurally characterized by single-crystal X-ray diffraction. The 1H
NMR spectra of 9aꢀc showed two distinct Cp* signals. The
presence of a μ-CH terminus in the azahexatrienyl linkage was
Figure 7. ORTEP drawing of 8, showing 35% thermal ellipsoids.
Hydrogen atoms except for H1 are omitted. Selected bond lengths
(Å) and angles (deg): Ru1ꢀRu2 = 2.8469(7); Ru1ꢀN1 = 2.093(3);
Ru1ꢀC1 = 2.306(4); Ru1ꢀC2 = 2.098(4); Ru2ꢀN1 = 2.242(3);
Ru2ꢀC2 = 2.098(4); Ru2ꢀC3 = 2.182(5); Ru2ꢀC4 = 2.129(5);
C1ꢀC2 = 1.386(6); C2ꢀC3 = 1.441(6); C3ꢀC4 = 1.400(6);
C4ꢀN1 = 1.384(5); N1ꢀC6 = 1.427(5); C1ꢀC2ꢀC3 = 140.9(4).
1
evidenced by characteristic downfield signals in the H and 13C
NMR spectra (e.g., δH = 11.54 and δC = 184.8 for 9a). The 1H
NMR spectra of 9a and 9b showed signals for the internal alkenyl
protons in a region consistent with the π-allyl-like bonding (e.g., δ
4.67 and 3.32 for 9a).
Figure 8. ORTEP drawing of the cationic part of 9a, showing 35%
thermal ellipsoids. Hydrogen atoms are omitted. Selected bond lengths
(Å): Ru1ꢀRu2 = 2.7394(7); Ru1ꢀN1 = 2.103(4); Ru1ꢀC1 =
2.107(5); Ru1ꢀC2 = 2.228(5); Ru1ꢀC3 = 2.168(5); Ru2ꢀN1 =
2.126(4); Ru2ꢀC1 = 2.036(5); Ru2ꢀC4 = 2.168(5); Ru2ꢀC5 =
2.174(5); C1ꢀC2 = 1.417(6); C2ꢀC3 = 1.412(6); C3ꢀC4 =
1.484(6); C4ꢀC5 = 1.407(7); C5ꢀN1 = 1.410(6); N1ꢀC6 = 1.427(6).
The X-ray structure of the cationic part of 9a is shown in
Figure 8. The μ-azahexatrienyl ligand forms an S-shaped structure
comprised of a π-allyl-like C1ꢀC2ꢀC3 unit and an aza-π-allyl-
like C4ꢀC5ꢀN1 unit. The CꢀC and CꢀN bond lengths
(1.407(7)ꢀ1.417(6) Å) within these allylic units are intermediate
between single- and double-bond distances. In contrast, the
C3ꢀC4 bond that connects the two allylic units is long
(1.484(6) Å) and can be formulated as a CꢀC single bond.
The RuꢀRu distance of 2.7394(7) Å is consistent with a RuꢀRu
single bond. Complex 9b also has similar structural features (see
Supporting Information).
(1.384(5)ꢀ1.441(6) Å) that are intermediate between single-
and double-bond distances.
Alkyne Coupling Reactivity Involving Both RuꢀN and Ruꢀ
C Multiple Bonds. It has been known that MꢀN multiple bonds
of μ-imido complexes36 and MꢀC multiple bonds of
μ-alkylidyne complexes90 undergo cycloaddition reactions with
Although efforts to detect intermediates such as a monoalkyne
adduct were unsuccessful, the structures of the products 9aꢀc
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are informative enough to suggest a possible reaction mechan-
ism, which is shown in Scheme 3. The presence of π-allyl- and
aza-π-allyl-type structures in the products suggests that the initial
steps of the reaction would be the cycloaddition of alkynes to the
RuꢀC and RuꢀN multiple bonds to give the intermediate E,
containing the ruthenacyclobutene and azaruthenacyclobutene
structures. The Markovnikov regiochemistry in these cycloaddi-
tion steps would be sterically favored, as it could avoid repulsion
between the alkyne substituents and the Cp* ligands. The CꢀC
coupling between the resulting metallacycle moieties and sub-
sequent π coordination of alkyne-derived carbon atoms would
furnish the observed products.
Deuteratedsolvents were obtainedfrom Cambridge Isotope Laboratories,
Inc., degassed, and stored over activated 4A molecular sieves. [Cp*Ru(μ-
NHPh)]2 was prepared from [Cp*Ru(μ3-Cl)]4 by a modification of the
literature method;47 LiNHPh (prepared from n-BuLi and NH2Ph) was
used instead of NaNHPh 0.3THF, and the product was crystallized from
3
a layered solution of toluene/hexanes in 60ꢀ70% yield as dark blue block
crystals. Other reagents were purchased from commercial vendors and
used without further purification unless otherwise noted. 1H and 31P{1H}
NMR spectra were recorded on a JEOL ECP500 spectrometer at the field
strength of 500.16 and 202.48 MHz, respectively. 13C{1H} NMR spectra
were obtained ona Varian VNMR400 spectrometer atthefieldstrengthof
100.55 MHz. Infrared spectra were obtained using a JASCO FT-IR 4100
spectrometer. FAB-MS spectra were recorded on a JEOL JMS700
spectrometer. Elemental analyses were performed on a Perkin-Elmer
2400 Series II CHNS/O analyzer.
’ CONCLUSION
[(Cp*Ru)2(μ-NPh)(μ-CO)] (2a). To a solution of 1 (210 mg, 0.320
mmol) in THF (15 mL) was added CO (11 mL) at room temperature.
The color of the solution instantly changed from blue to yellow and then
gradually to dark orange. After stirring overnight at room temperature,
the solvent was removed in vacuo, and the remaining solid was extracted
with hexanes (total 30 mL). The extract was concentrated to 10 mL
and set aside for 1 day. Red crystals of 2a were collected by filtration
and dried under vacuum. Yield: 120 mg, 63%. Anal. Calcd for
C27H35NORu2: C, 54.81; H, 5.96; N, 2.37. Found: C, 54.87; H, 5.95;
N, 2.33. 1H NMR (C6D6): δ 7.38 (t, 2H, Ph), 7.16 (t, 1H, Ph), 7.12 (d,
2H, Ph), 1.63 (s, 30H, Cp*). 13C{1H} NMR (toluene-d8, 22 °C): δ
258.7 (μ-CO), 168.5, 122.1, 117.6 (Ph), 91.0 (C5Me5), 9.8 (C5Me5). IR
(KBr): 1744 cmꢀ1 (ν(CO)).
[(Cp*Ru)2(μ-t-BuNC)(μ-NPh)] (2b). To a solution of 1 (687 mg,
1.05 mmol) in THF (25 mL) was added a solution of t-BuNC (110 μL,
1.05 mmol) in 5 mL of THF at ꢀ80 °C. The dark violet solution was
allowed to warm slowly to room temperature and stirred for 4 h. The
solvent was removed in vacuo, and the residue was recrystallized from
cold tolueneꢀacetonitrile to afford 2b as dark red crystals. Yield: 561
mg, 83%. Anal. Calcd for C31H44N2Ru2: C, 57.56; H, 6.86; N, 4.33.
Found: C, 57.76; H, 6.97; N, 4.39. 1H NMR (C6D6): δ 7.38 (t, 2H, Ph),
7.13 (t, 2H, Ph), 7.01 (d, 1H, Ph), 1.97 (s, 9H, t-Bu), 1.56 (s, 30H, Cp*).
13C{1H} NMR (C6D6): δ 212.9 (CN), 170.7, 122.4, 118.5 (Ph), 88.3
(C5Me5), 59.1 (CMe3), 32.2 (CMe3), 10.8 (C5Me5). IR (KBr):
1809 cmꢀ1 (ν(CN)).
We have synthesized and characterized a series of dinuclear
ruthenium bridging imido complexes [(Cp*Ru)2(μ-NPh)(μ-
L)]nþ (n = 0 or 1) containing a variety of organometallic
functionalities (i.e., CO, t-BuNC, CH2, vinylidene, alkylidyne).
The synthesis of these imido complexes is based on the addition
of π-acceptor ligands to the bis-amido complex 1, which induces
disproportionation of the two amido ligands into free aniline and
the imido ligand. In addition, modification of the μ-methylene
and μ-vinylidene ligands turned out to be an effective way to
synthesize the imidoꢀalkylidyne derivatives.
All of these complexes feature the delocalized multiple bonds
over the RuꢀNꢀRu unit, which should contribute to make these
coordinatively unsaturated complexes sufficiently stable to be
isolated. The imidoꢀalkylidyne complexes also possess the
multiply bonded RuꢀC linkage. The presence of a net RuꢀRu
bonding character has been suggested by DFT calculations; the
major bonding contributions characterized are the formation of a
π-bonding molecular orbital that spreads over the Ru2N unit and
the back-donation of RuꢀRu σ* electrons into the bridging
carbon moiety, which leaves a net RuꢀRu σ-bonding interaction.
The latter role of π-acceptor ligands in RuꢀRu bonding may
explain the absence of RuꢀRu bond formation in the reaction of
1 with the σ-donor PMe3, which gives the monomeric adduct
[Cp*Ru(NHPh)(PMe3)2].47
[(Cp*Ru)2(μ-CH2)(μ-NPh)] (2c). To a stirred suspension of
[Ph2SMe][BF4] (1.09 g, 3.78 mmol) in THF (10 mL) was added
dropwise a solution of NaN(SiMe3)2 in THF (1.09 M, 3.81 mL, 4.16
mmol) at ꢀ80 °C. The mixture was slowly warmed to ꢀ10 °C to form a
clear yellow solution. The solution was cooled again to ꢀ80 °C and
transferred via cannula to a cooled (ꢀ80 °C) stirred solution of 1 (2.60
g, 3.78 mmol) in 20 mL of THF. The combined solution was allowed to
warm slowly to room temperature and stirred for 12 h. The solvent was
removed in vacuo, and the residue was extracted with toluene (total
80 mL). The extract was concentrated (ca. 20 mL), layered with
acetonitrile (40 mL), and stood for 2 days to give 2c as dark red needles.
Yield: 1.58 g, 71%. Anal. Calcd for C27H37NRu2: C, 56.13; H, 6.46; N,
2.42. Found: C, 55.97; H, 6.36; N, 2.84. 1H NMR (C6D6): δ 12.79 (s,
2H, CH2), 7.36 (t, 2H), 7.19 (d, 2H), 7.14 (t, 1H, Ph), 1.63 (s, 30H,
Cp*). 13C{1H} NMR (C6D6): δ 186.6 (CH2), 168.9, 136.42, 131.35,
120.3 (Ph), 86.1 (C5Me5), 10.7 (C5Me5).
[(Cp*Ru)2(μ-NPh)(μ-CdCHSiMe3)] (2d). To a solution of 1
(0.40 g, 0.61 mmol) in THF (15 mL) was added at ꢀ80 °C a solution of
Me3SiCtCH (85 μL, 0.61 mmol) in THF (5 mL). The mixture was
allowed to warm slowly to room temperature and stirred for 12 h.
Evaporation of the solution afforded 2d as a maroon solid. Yield: 0.40 g,
99%. Anal. Calcd for C31H45NSiRu2: C, 56.25; H, 6.85; N, 2.12. Found:
C, 56.08; H, 6.77; N, 2.54. 1H NMR (C6D6): δ 7.32 (t, 2H, Ph), 7.14 (t,
1H, Ph), 6.99 (d, 2H, Ph), 6.97 (s, 1H, CdCHSiMe3), 1.49 (s, 30H,
Owing to the coordinatively unsaturated nature of the ruthe-
nium centers, these imido complexes are highly reactive toward
incoming substrates. The diverse combination of the imidodir-
uthenium fragment (Cp*Ru)2(μ-NPh) with an additional orga-
nometallic functional group allows us to observe a number of
ligand coupling reactions that are unprecedented in transition
metal imido chemistry. These include the imidoꢀCOꢀ
methylene and imidoꢀCOꢀvinylidene coupling reactions ob-
served for 2c and 2e, the formation of allenylimine ligand in the
reaction of 2c with Me3SiCtCH, and the imidoꢀalkyneꢀ
alkyneꢀmethylidyne coupling reaction observed for the imido
methylidyne complex 2h0. The last example is quite characteristic
to this RuꢀN and RuꢀC multiply bonded system, as the reaction
appears to proceed via double alkyne cycloaddition to these
multiple bonds followed by dinuclear CꢀC coupling of the
ruthenacyclobuteneꢀazaruthenacyclobutene moieties.
’ EXPERIMENTAL SECTION
General Remarks. All manipulations were performed under an
atmosphere of nitrogen using standard Schlenk techniques. Anhydrous
solvents (toluene, hexanes, THF, acetonitrile, and 2-propanol) were
purchased from Kanto Chemical Co., Inc. and degassed before use.
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Cp*), 0.86 (s, 9H, SiMe3). 13C{1H} NMR (C6D6): δ 314.8
(CCHSiMe3), 168.6, 129.4, 123.2, 119.4 (Ph), 117.7 (CCHSiMe3),
90.7 (C5Me5), 10.0 (C5Me5), 5.06 (SiMe3).
(1.0 M, 0.545 mL, 0.545 mmol). After stirring overnight at room
temperature, the solution was evaporated to dryness, and the remaining
solid was extracted with hexanes (10 mL). The extract was concentrated
to 1 mL and set aside for 1 day. Dark orange crystals of 3a were collected
by filtration and dried in vacuo. Yield: 87 mg (60%). Anal. Calcd for
C30H44NOPRu2: C, 53.96; H, 6.64; N, 2.10. Found: C, 53.60; H, 6.53;
N, 2.31. 1H NMR (C6D6): δ 7.54 (d, 2H, Ph), 7.34 (t, 2H, Ph), 6.99 (t,
1H, Ph), 1.85 (s, 15H, Cp*), 1.70 (d, 4JPH = 1.4 Hz, 15H, Cp*), 0.76 (d,
2JPH = 9.0 Hz, 9H, PMe3). 13C{1H} NMR (C6D6): δ 260.2 (μ-CO),
165.7, 128.5, 128.3, 123.4 (Ph), 94.1, 89.3 (C5Me5), 17.5 (d, 1JPC = 28.8
Hz, PMe3), 10.9, 10.8 (C5Me5). 31P{1H} NMR (C6D6): δ 7.8 (s). IR
(KBr): 1731 cmꢀ1 (ν(CO)).
[(Cp*Ru)2(μ-NPh)(μ-CdCH2)] (2e). To a solution of 1 (0.40 g,
0.61 mmol) in toluene (10 mL) was added Me3SiCtCH (86 μL, 0.61
mmol) at room temperature. After 20 min, t-BuOH (1 mL) was added.
The mixture was stirred for 2.5 h and evaporated to dryness. The residue
was washed with diethyl ether (10 mL) to give 2e as a gray-violet
microcrystalline solid. Yield: 0.23 g, 64%. Anal. Calcd for C28H37NRu2:
C, 57.03; H, 6.32; N, 2.38. Found: C, 56.91; H, 6.52; N, 2.50. 1H NMR
(C6D6): δ 7.35 (t, 2H, Ph), 7.15 (t, 1H, Ph), 7.05 (d, 2H, Ph), 6.55 (s,
2H, CdCH2), 1.51 (s, 30H, Cp*). 13C{1H} NMR (C6D6): δ 304.0
(CCH2), 168.3, 128.2, 122.7, 119.3 (Ph), 105.6 (CCH2), 89.3 (C5Me5),
9.5 (C5Me5).
[(Cp*Ru)2(μ-NPh)(μ-CMe)]OTf (2f). To a solution of 2e (0.139
g, 0.236 mmol) in toluene (5 mL) was added HOTf (21 μL, 0.236
mmol) at room temperature. The mixture was stirred for 10 min and
evaporated to dryness. Recrystallization of the residue from CH2Cl2/
hexanes afforded 2f as red needles. Yield: 0.163 g, 93%. Anal. Calcd for
C29H38NO3F3SRu2: C, 47.08; H, 5.18; N, 1.89. Found: C, 46.87; H,
5.27; N, 1.85. 1H NMR (CD2Cl2): δ 7.46 (t, 2H, Ph), 7.39 (t, 1H, Ph),
6.68 (d, 2H, Ph), 3.87 (s, 3H, CMe), 1.63 (s, 30H, Cp*). 13C{1H} NMR
(CD2Cl2): δ 384.4 (CMe), 164.3, 129.2, 126.7, 117.3 (Ph), 121.3 (q, J =
319 Hz, CF3SO3), 102.3 (C5Me5), 45.5 (CMe), 9.8 (C5Me5).
[(Cp*Ru)2(μ-NPh)(μ-CEt)]OTf (2g). To a solution of 2e (60 mg,
0.10 mmol) in toluene (8 mL) was added MeOTf (12 μL, 0.11 mmol) at
room temperature. The mixture was stirred for 12 h and evaporated to
dryness. Recrystallization of the residue from THF/hexanes afforded 2g
as red needles. Yield: 71 mg, 94%. Anal. Calcd for C30H40NO3F3SRu2:
C, 47.80; H, 5.35; N, 1.86. Found: C, 47.77; H, 4.94; N, 1.64. 1H NMR
(CD2Cl2): δ 7.49 (t, 2H, Ph), 7.43 (t, 1H, Ph), 6.66 (d, 2H, Ph), 4.46 (q,
J = 7.6 Hz, 2H, CH2CH3), 1.64 (s, 30H, Cp*), 1.60 (t, J = 7.6 Hz, 3H,
CH2CH3). 13C{1H} NMR (CD2Cl2): δ 391.5 (CCH2CH3), 164.1,
129.3, 126.9, 117.1 (Ph), 121.3 (q, J = 319 Hz, CF3SO3), 102.6 (C5Me5),
49.8 (CCH2CH3), 11.7 (CCH2CH3), 9.9 (C5Me5).
[(Cp*Ru)2(μ-NPh)(μ-CH)]BF4 (2h). A stirred solution of 2c (470
mg, 0.814 mmol) in toluene (15 mL) was cooled to ꢀ80 °C and treated
with Ph3CBF4 in CH2Cl2 (1.0 mol/L, 0.81 mL). The mixture was
allowed to warm to room temperature with stirring over 3 h and then
evaporated to dryness. Theresidue waswashedtwice with 5 mLof diethyl
ether, and the remaining solid was recrystallized from THF at ꢀ30 °C to
give 2h as a brown crystalline solid. Yield: 380 mg, 70%. Anal. Calcd for
C27H36BNF4Ru2: C, 48.87; H, 5.47; N, 2.11. Found: C, 49.10; H, 5.46;
N, 1.98. 1H NMR (CD2Cl2): δ 18.15 (s, 1H, μ-CH), 7.47 (m, 3H, Ph),
6.76 (d, 2H, Ph), 1.77 (s, 30H, Cp*). 13C{1H} NMR (CD2Cl2): δ 377.1
(μ-CH), 165.0, 129.6, 126.8, 117.0 (Ph), 103.5 (C5Me5), 10.7 (C5Me5).
The μ-CH signalwas observed byusing a 13C-enrichedsample of 2h. The
13C-enriched 2h was prepared from 13C-enriched 2c. The 13C-enriched
2c was prepared using the sulfonium salt [Ph2S13CH3][OTf]. This
sulfonium salt was prepared from the commercially available 13CH3OTf
and Ph2S according to the literature method.92
[(Cp*Ru)2(μ-NPh)(μ-t-BuNC)(PMe3)] (3b). To a solution of 2b
(148 mg, 0.229 mmol) in hexanes (15 mL) was added a THF solution of
PMe3 (1.0 M, 570 μL, 0.57 mmol). After stirring overnight at room
temperature, the solution was concentrated to ca. 1 mL and set aside for
1 day at ꢀ30 °C to give dark brown crystals of 3b, which were collected
by filtration and dried in vacuo. Yield: 98 mg, 59%. Anal. Calcd for
C34H53N2PRu2: C, 56.49; H, 7.39; N, 3.88. Found: C, 56.40; H, 7.58; N,
3.76. 1H NMR (C6D6): δ 7.59 (d, 2H, Ph), 7.33 (t, 2H, Ph), 7.00 (t, 1H,
Ph), 1.81 (s, 15H, Cp*), 1.75 (d, 4JPH = 1.5 Hz, 15H, Cp*), 1.63 (s, 9H, t-
Bu), 0.75 (d, 2JPH = 9.0 Hz, 9H, PMe3). 13C{1H} NMR (C6D6): δ 215.4
2
(t-BuNC), 164.8, 124.5, 123.7, 117.2 (Ph), 92.5 (d, JPC = 3.1 Hz,
C5Me5), 86.4 (C5Me5), 58.3 (CMe3), 32.1 (CMe3), 19.3 (d, 1JPC = 28.8
Hz, PMe3), 12.1, 11.3 (C5Me5). 31P{1H} NMR (C6D6): δ 1.3 (s). IR
(KBr): 1759 cmꢀ1 (ν(CN)).
[(Cp*Ru)2(μ-NPh)(μ-CH2)(PMe3)] (3c). To a solution of 2c (126
mg, 0.218 mmol) in THF (10 mL) was added a THF solution of PMe3
(1.0 M, 0.545 mL, 0.545 mmol). After stirring overnight at room
temperature, the solution was evaporated to dryness, and the remaining
solid was extracted with hexanes (10 mL). The extract was concentrated
to 1 mL and set aside for 1 day to give 3c as dark blue crystals. Yield: 85
mg, 60%. Anal. Calcd for C30H46NPRu2: C, 55.11; H, 7.09; N, 2.14.
Found: C, 55.21; H, 7.57; N, 2.37. 1H NMR (C6D6): δ 10.23 (d, 2JHH
=
2.0 Hz, 1H, CH2), 8.83 (dd, 2JHH = 2.0 Hz, 3JPH = 15.1 Hz, 1H, CH2),
7.52 (d, 2H, Ph), 7.34 (t, 2H, Ph), 6.93 (t, 1H, Ph), 1.77 (s, 15H, Cp*),
1.68 (d, 4JPH = 1.0 Hz, 15H, Cp*), 0.82 (d, 2JPH = 8.3 Hz, 9H, PMe3).
13C{1H} NMR (C6D6): δ 165.8 (Ph), 161.5 (d, 2JPC = 9.6 Hz, CH2),
128.3, 123.3, 115.8 (Ph), 94.3, 84.0 (C5Me5), 18.2 (d, 1JPC = 26.9 Hz,
PMe3), 11.6, 11.0 (C5Me5). 31P{1H} NMR (C6D6): δ 13.1 (s).
[(Cp*Ru)2(μ-NPh)(μ-CH2)(t-BuNC)2] (4c). To a solution of 2c
(291 mg, 0.504 mmol) in THF (15 mL) was added t-BuNC (0.590 mL,
5.03 mmol), and the mixture was stirred overnight at room temperature.
The solution was evaporated to dryness, and the residue was extracted
with hexanes (15 mL). The extract was concentrated to 1 mL and set
aside for 1 day to give 4c as dark yellowcrystals. Yield: 232 mg, 62%. Anal.
Calcd for C37H55N3Ru2: C, 59.73; H, 7.45; N, 5.65. Found: C, 59.99; H,
7.77; N, 6.15. 1H NMR (C6D6): δ 8.56, 7.77 (s, 1H each, CH2), 7.20 (t,
2H, Ph), 7.13 (d, 2H, Ph), 6.68 (t, 1H, Ph), 1.89 (s, 30 H, Cp*), 1.07 (s,
18 H, t-Bu). 13C{1H} NMR (C6D6): δ 180.6 (t-BuNC), 172.8 (μ-CH2),
135.2, 127.2, 118.6, 112.4 (Ph), 97.5 (C5Me5), 55.6 (CMe3), 31.9
(CMe3), 11.2 (C5Me5). IR (KBr): 2102, 2040 cmꢀ1 (ν(CN)).
[(Cp*Ru)2(μ-NPh)(μ-CH)]OTf (2h0). 2h (471 mg, 0.710 mmol)
and NaOTf (6.11 g, 35.5 mmol) were dissolved in 50 mL of acetone, and
the solution was stirred at room temperature for 1 h. After removal of the
solvent under reduced pressure, the residue was extracted with CH2Cl2
(total 70 mL). The extract was concentrated to ca. 4 mL and layered with
diethyl ether (20 mL) to give 2h0 as brown crystals. Yield: 439 mg, 85%.
Anal. Calcd for C28H36NO3F3SRu2: C, 46.34; H, 5.00; N, 1.93. Found:
C, 46.47; H, 4.71; N, 1.80. 1H NMR (acetone-d6): δ 18.60 (s, 1H, μ-
CH), 7.55 (t, 2H, Ph), 7.46 (t, 1H, Ph), 6.96 (d, 2H, Ph), 1.85 (s, 30H,
Cp*). 13C{1H} NMR (acetone-d6): δ 165.7, 130.1, 127.3, 118.1 (Ph),
122.2 (q, J = 320 Hz, CF3SO3), 104.0 (C5Me5), 10.7 (C5Me5).
[(Cp*Ru)2(μ-NPh)(μ-CO)(PMe3)] (3a). To a solution of 2a (129
mg, 0.218 mmol) in THF (10 mL) was added a THF solution of PMe3
[(Cp*Ru)2(μ-NPh)(μ-CdCH2)(t-BuNC)2] (4e). To a solution of
2e (0.10 g, 0.17 mmol) in toluene (12.5 mL) was added t-BuNC (86 μL,
0.76 mmol), and the mixture was stirred for 30 min at room temperature.
The solution was evaporated to dryness, and the residue was extracted
with hexanes (10 mL). The extract was concentrated to 1 mL and set
aside for 1 day to give 4e as dark yellow crystals. Yield: 73 mg, 57%. Anal.
Calcd for C38H55N3Ru2: C, 60.37; H, 7.33; N, 5.56. Found: C, 60.43; H,
7.71; N, 5.36. 1H NMR (C6D6): δ 7.20 (t, 2H, Ph), 7.06 (d, 2H, Ph),
6.67 (t, 1H, Ph), 5.74 (s, 2H, CdCH2), 1.91 (s, 30 H, Cp*), 1.06 (s, 18
H, t-Bu). 13C{1H} NMR (C6D6): δ 268.5 (CCH2), 180.2 (CN), 167.8,
127.3, 117.9, 112.6 (Ph), 109.2 (CCH2), 98.0 (C5Me5), 55.6 (CMe3),
31.7 (CMe3), 10.9 (C5Me5). IR (KBr): 2091, 2044 cmꢀ1 (ν(CN)).
2168
dx.doi.org/10.1021/om1011227 |Organometallics 2011, 30, 2160–2172

Organometallics
ARTICLE
Reaction of 2a with CO: Formation of [Cp*Ru(CO)2]2 and
PhNCO. In a 25 mL Schlenk flask, the imido complex 2a (23.3 mg,
0.0394 mmol) and 1,3,5-trimethoxybenzene (an internal standard, 3.3
mg, 0.0197 mmol) were dissolved in C6D6 (1 mL). The solution was
frozen, evacuated, and thawed. Then, CO was introduced into the flask,
and the mixture was stirred under a CO atmosphere for 14 h. The 1H
NMR spectrum showed the formation of [Cp*Ru(CO)2]2 (90%, δ
1.71) and PhNCO (20%). The existence of PhNCO was also confirmed
by a GC-MS analysis. Data for PhNCO: 1H NMR (C6D6) δ 6.82 (m,
C32H39NO3Ru2: C, 55.88; H, 5.72; N, 2.04. Found: C, 56.17; H, 5.72; N,
2.04. 1H NMR (C6D6): δ 7.94 (br, 2H, aryl), 7.13 (d, 2H, aryl), 4.08,
4.02 (d, J = 2.0 Hz, 1H each, CdCH2), 2.24 (s, 3H, C6H4Me), 1.56, 1.51
(s, 15H each, Cp*). 13C{1H} NMR (C6D6): δ 220.6, 207.4 (Ru-CO),
174.3, 174.2 (s, CH2dCCONAr), 144.8, 129.2, 128.9, 123.6 (aryl), 99.6,
97.0 (C5Me5), 48.6 (s, CH2dCCONAr), 21.0 (s, C6H4Me), 9.6, 9.4
(C5Me5). IR (Nujol): 2723 (w), 1937 (s), 1857 (s), 1614 (s), 1600 (s),
1501 (s), 1344 (s), 1304 (w), 1275 (w), 1184 (w), 1162 (w), 1109 (w),
1030 (m), 910 (w), 829 (m), 755 (w), 723 (w), 705 (w), 563 (m) cmꢀ1
.
1
2H), 6.76 (m, 1H), 6.57 (m, 2H); MS(EI) m/z 119, 91, 64. The H
[(Cp*Ru)2{μ-Me3SiCHdCdC(SiMe3)C(Me)dNPh}] (8). To a
solution of 2c (154 mg, 0.267 mmol) in THF (7.5 mL) was added
trimethylsilylacetylene (184 μL, 1.33 mmol) at room temperature. After
stirring for 14 h, the solution was evaporated to dryness. Recrystallization
of the residue from THF/acetonitrile afforded8 as dark red crystals. Yield:
182 mg, 88%. Anal. Calcd for C37H57N2Si2Ru2: C, 57.40; H, 7.42; N, 1.81.
Found: C, 57.22; H, 7.29; N, 1.89. 1H NMR (C6D6): δ 7.16 (m, 1H, Ph),
7.04 (m, 1H, Ph), 6.99 (m, 1H, Ph), 6.88 (m, 1H, Ph), 6.85 (m, 1H, Ph),
4.22 (s, 1H, CHSiMe3), 1.99 (s, 3H, Me), 1.84, 1.15 (s, 15H each, Cp*),
0.50, 0.36 (s, 9H each SiMe3). 13C{1H} NMR (C6D6): δ 183.5
(Me3SiCHdCdC(SiMe3)C(Me)dNPh), 153.3, 128.5, 126.9, 126.2,
125.7, 125.3 (Ph), 114.0 (Me3SiCHdCdC(SiMe3)C(Me)dNPh),
84.7, 82.0 (C5Me5), 58.7 (Me3SiCHdCdC(SiMe3)C(Me)dNPh),
50.9 (Me3SiCHdCdC(SiMe3)C(Me)dNPh), 16.1 (Me3SiCHdC
dC(SiMe3)C(Me)dNPh), 11.4, 10.4 (C5Me5), 2.4, 2.2 (SiMe3).
[(Cp*Ru)2{μ-HC(RCCH)(HCCR)NPh}]OTf (9a, R = p-tolyl). To
a solution of 2h0 (112 mg, 0.154 mmol) in 10 mL of THF was added p-
tolylacetylene (195 μL, 1.54 mmol), and the solution was stirred at 60 °C
for 4 h. Volatiles were removed under reduced pressure, and the residue
was washed with hexanes. The remaining solid was recrystallized from
THF/Et2O to give 9a as reddish-purple block crystals. Yield: 88.4 mg,
70%. Anal. Calcd for C46H52NO3F3SRu2: C, 57.66; H, 5.47; N, 1.46.
Found: C, 57.57; H, 5.48; N, 1.42. 1H NMR (acetone-d6): δ 11.54 (d, J =
2.6 Hz, 1H, HC(RCCH)(HCCR)NPh), 7.71ꢀ6.81 (m, 13H, aryl), 4.67
(dd, J = 2.6 and 2.0 Hz, 1H, HC(RCCH)(HCCR)NPh), 3.32 (d, J = 2.0
Hz, 1H, HC(RCCH)(HCCR)NPh), 2.38, 2.27 (s, 3H each, C6H4Me),
1.70, 1.11 (s, 15H each, C5Me5). 13C{1H} NMR (acetone-d6): δ 184.8
(HC(RCCH)(HCCR)NPh), 152.8, 141.2, 140.6, 132.9, 130.4, 130.0,
129.6, 129.0, 128.7, 128.4, 128.0, 126.5 (aryl), 122.2 (q, J = 320 Hz,
CF3SO3), 126.4 (HC(RCCH)(HCCR)NPh), 117.8 (HC(RCCH)
(HCCR)NPh), 99.8, 98.7 (C5Me5), 71.8 (HC(RCCH)(HCCR)NPh),
70.0 (HC(RCCH)(HCCR)NPh), 21.3, 21.3 (C6H4Me), 10.6, 9.3
(C5Me5). FAB-MS: m/z 809 [M]þ.
[(Cp*Ru)2{μ-HC(RCCH)(HCCR)NPh}]OTf (9b, R = n-Bu). To
a solution of 2h0 (184 mg, 0.254 mmol) in 10 mL of THF was added
1-hexyne (292 μL, 2.50 mmol), and the solution was stirred at 60 °C for
7 h. Volatiles were removed under reduced pressure, and the residue was
washed with hexanes. The remaining solid was recrystallized from THF/
Et2O to give 9b as reddish-purple block crystals. Yield: 107.5 mg, 47%.
Anal. Calcd for C40H56NO3F3SRu2: C, 53.98; H, 6.34; N, 1.57. Found:
C, 54.25; H, 6.59; N, 1.36. 1H NMR (acetone-d6): δ 10.90 (d, J = 1.9 Hz,
1H, HC(RCCH)(HCCR)NPh), 7.77, 7.64, 7.61, 7.46, 6.73 (m, 1H,
Ph), 3.81 (pseudo t, J = 1.9 Hz, HC(RCCH)(HCCR)NPh), 2.80 (d, J =
1.9 Hz, HC(RCCH)(HCCR)NPh), 2.18ꢀ1.44 (m, 12H, n-Bu), 1.90,
1.42 (s, 15H each, Cp*), 0.97, 0.82 (t, 3H each, n-Bu). 13C{1H} NMR
(acetone-d6): δ 193.1 (HC(RCCH)(HCCR)NPh), 151.5, 130.3, 130.2,
129.7, 128.5, 126.6 (Ph), 123.8 (HC(RCCH)(HCCR)NPh), 122.3 (q,
J = 320 Hz, CF3SO3), 98.9, 98.1 (C5Me5), 77.8 (HC(RCCH)
(HCCR)NPh), 71.4 (HC(RCCH)(HCCR)NPh), 68.2 (HC(RCCH)
(HCCR)NPh), 34.9, 32.5 (CH2CH2CH2CH3), 30.2, 26.3 (CH2CH2
CH2CH3), 23.5, 23.3 (CH2CH2CH2CH3), 14.4, 13.9 (CH2CH2CH2
CH3), 10.6, 9.3 (C5Me5). FAB-MS: m/z 741 [M]þ.
NMR spectrum also contained unidentified signals in the aromatic
region: δ 7.76 (m), 7.48 (m), 7.35 (m), 7.30 (m), 7.23 (m), 7.15 (m),
7.09 (m).
[(Cp*Ru)2(μ-t-BuNCHNC6H4)(t-BuNC)3] (5). To a solution of
2b (67 mg, 0.10 mmol) in THF (10 mL) was added t-BuNC (0.11 mL,
1.0 mmol). The mixture was stirred for 2 days at room temperature to
give a yellow solution. The solution was evaporated to dryness, and the
residue was extracted with hexanes (10 mL). The extract was concen-
trated to 1 mL and set aside for 1 day to give 5 as a yellow crystalline
solid. Yield: 64 mg, 69%. The product was obtained as a 2:1 mixture of
two isomers. Anal. Calcd for C46H71N5Ru2: C, 61.65; H, 7.98; N, 7.81.
Found: C, 61.70; H, 8.01; N, 7.70. 1H NMR (C6D6): major isomer, δ
9.97 (s, 1H, NCHN), 7.95 (d, 1H, C6H4), 7.3ꢀ7.2 (m, 2H, C6H4), 6.86
(m, 1H, C6H4), 2.00 (s, 15H, Cp*), 1.95 (s, 15H, Cp*), 1.60 (s, 18H, t-
Bu), 1.28 (s, 9H, t-Bu), 1.16 (s, 9H, t-Bu); minor isomer, δ 8.95 (s, 1H,
NCHN), 7.60 (d, 1H, C6H4), 7.3ꢀ7.2 (m, 2H, C6H4), 6.88 (m, 1H,
C6H4), 1.96 (s, 15H, Cp*), 1.81 (s, 15H, Cp*), 1.44 (s, 9H, t-Bu), 1.34
(s, 9H, t-Bu), 1.15 (s, 18H, t-Bu). MS (FAB): m/z 897 [M]þ, 814 [M(t-
BuNC)]þ, 731 [M ꢀ 2(t-BuNC)]þ, 648 [M ꢀ 3(t-BuNC)]þ.
[{Cp*Ru(CO)2}2(μ-PhNCOCH2)] (6). A solution of 2c (108 mg,
0.187 mmol) in 10 mL of THF was placed in a 25 mL Schlenk flask, and
the solution was frozen, evacuated, and thawed. CO was introduced to
the flask, and the mixture was stirred for 2 days. The solvent was
removed in vacuo, and the residue was extracted with hexanes (10 mL).
The extract was concentrated to 1 mL and set aside for 1 day under a CO
atmosphere. The yellow crystals of 6 deposited were collected by
filtration and dried in vacuo. Yield: 98 mg, 73%. Anal. Calcd for
C32H37NO5Ru2: C, 53.55; H, 5.20; N, 1.95. Found: C, 53.90; H,
5.05; N, 2.11. 1H NMR (C6D6): δ 7.45 (d, 2H, Ph), 7.29 (t, 2H, Ph),
7.00 (t, 1H, Ph), 2.13 (s, 2H, CH2), 1.61 (s, 15H, Cp*), 1.48 (s, 15H,
Cp*). 13C{1H} NMR (C6D6): δ 204.7, 202.5 (Ru-CO), 185.2
(PhNCOCH2), 158.4, 128.9, 128.3, 122.6 (Ph), 99.8, 98.4 (C5Me5),
9.8, 9.5 (C5Me5), 6.9 (CH2). MS (FAB): m/z 719 [M]þ, 691 [M ꢀ
2CO]þ, 663 [M3CO]þ, 635 [M3CO]þ, 607 [M4CO]þ. IR (KBr):
2020, 1998, 1945 cmꢀ1 (ν(CO)).
[{Cp*Ru(CO)}2(μ-CH2dCCONPh)] (7). Complex 2e (0.14 g,
0.24 mmol) was dissolved in 20 mL of toluene in a 25 mL Schlenk flask
under nitrogen. The flask was evacuated, and CO was introduced to the
flask at room temperature. After stirring for 30 min, the solvent was
removed in vacuo, and the residue was recrystallized from toluene/
hexanes to give 7 as red plate crystals. Yield: 0.11 g, 69%. Anal. Calcd for
C31H37NO3Ru2: C, 55.26; H, 5.54; N, 2.08. Found: C, 55.66; H, 5.75; N,
2.10. 1H NMR (C6D6): δ 8.00 (br, 2H, Ph), 7.31 (t, 2H, Ph), 6.89 (t, 1H,
Ph), 4.07, 4.01 (d, J = 2.0 Hz, 1H each, CdCH2), 1.54, 1.50 (s, 15H each,
Cp*). 13C{1H} NMR (C6D6): δ 220.5, 207.3 (Ru-CO), 174.6, 174.0 (s,
CH2dCCONPh), 147.3, 128.5, 123.6, 120.2 (Ph), 99.7, 97.0 (C5Me5),
48.8 (s, CH2dCCONPh), 9.5, 9.3 (C5Me5). IR (Nujol): 2723 (w), 2524
(w), 2503 (w), 2445 (w), 2341 (w), 2205 (w), 2059 (w), 1940 (s), 1848
(s), 1614 (s), 1578 (s), 1462 (s), 1342 (s), 1318 (s), 1303 (s), 1283 (m),
1182 (w), 1156 (m), 1067 (m), 1024 (m), 993 (m), 968 (w), 911 (w),
862 (w), 799 (w), 768 (s), 754 (s), 624 (w), 565 (s) cmꢀ1
.
[{Cp*Ru(CO)}2(μ-CH2dCCONAr)] (70, Ar = p-tolyl). This
compound was obtained in 62% yield from [(Cp*Ru)2(μ-NAr)(μ-
CdCH2)] in a manner similar to that described for 7. Anal. Calcd for
[(Cp*Ru)2{μ-HC(PhCCPh)(PhCCPh)NPh}]OTf (9c). Complex
2h0 (75.2 mg, 0.104 mmol) and diphenylacetylene (187 mg, 1.05 mmol)
were dissolved in 6 mL of CH2Cl2, and the solution was stirred at 80 °C
2169
dx.doi.org/10.1021/om1011227 |Organometallics 2011, 30, 2160–2172

Organometallics
ARTICLE
Table 3. Crystal Data and Structure Refinement Parameters for 2f, 3a, 4c, and 4e
2f CH2Cl2
3a
4c
4e
3
formula
fw
C
30H40NO3F3SCl2Ru2
C30H44NOPRu2
667.77
C37H55N3Ru2
743.98
23
C38H55N3Ru2
755.99
824.73
23
T (°C)
cryst syst
space group
a (Å)
23
23
monoclinic
P21/n (#14)
11.917(3)
24.975(8)
12.050(3)
90
monoclinic
P21/c (#14)
11.9490(10)
12.1985(13)
20.7663(16)
90
orthorhombic
Pbca (#61)
19.7902(10)
16.1809(7)
23.1204(8)
90
monoclinic
P21/c (#14)
10.463(3)
18.375(5)
19.380(5)
90
b (Å)
c (Å)
R (deg)
β (deg)
γ (deg)
V (Å3)
Z
107.903(10)
90
97.019(4)
90
90
93.921(12)
90
90
3412.5(15)
4
3004.2(5)
4
7403.7(6)
8
3717.1(16)
4
Dcalc (g/cm3)
1.605
1.476
1.335
1.351
μ (mmꢀ1
)
1.150
1.080
0.843
0.840
R1 [I > 2σ(I)]a
wR2 (all data)b
GOF on F2
0.0582
0.1486
0.962
0.0537
0.0365
0.0983
0.963
0.0328
0.1374
0.0890
1.021
1.035
a R1 = ∑ Fo| ꢀ |Fc /∑|Fo|. b wR2 = [∑(w(Fo ꢀ Fc2)2/∑w(Fo ) ]
.
2
2 2 1/2
Table 4. Crystal Data and Structure Refinement Parameters for 5, 70, 8, 9a, and 9b
5
70
8
9a
9b
formula
fw
C46H71N5Ru2
896.22
23
C32H39NO3Ru2
687.78
C37H57NSi2Ru2
774.16
C28H38NO3F3S2Ru2
727.79
C40H56NO3F3O2SRu2
890.06
T (°C)
cryst syst
space group
a (Å)
23
23
23
23
monoclinic
P21/c (#14)
13.590(4)
20.820(4)
16.966(4)
90
monoclinic
P21/a (#14)
18.720(4)
8.585(2)
19.149(4)
90
monoclinic
P21/c (#14)
13.738(4)
11.626(3)
23.086(8)
90
monoclinic
P21/n (#14)
16.583(8)
16.590(7)
11.075(5)
90
triclinic
P1 (#2)
9.499(3)
12.149(5)
18.523(9)
71.544(17)
81.347(17)
88.356(14)
2004.2(15)
2
b (Å)
c (Å)
R (deg)
β (deg)
γ (deg)
V (Å3)
Z
91.196(11)
90
105.616(9)
90
91.268(12)
90
90.39(2)
90
4800(2)
4
2963.9(11)
4
3686.6(18)
4
3047(2)
4
Dcalc (g/cm3)
1.240
1.541
1.395
1.587
1.475
μ (mmꢀ1
)
0.663
1.051
0.909
1.107
0.856
R1 [I > 2σ(I)]a
wR2 (all data)b
GOF on F2
0.0474
0.1300
0.994
0.0338
0.0479
0.0859
0.0456
0.0879
0.1331
0.2436
0.1187
1.065
1.028
0.963
1.016
a R1 = ∑ Fo| ꢀ |Fc /∑|Fo|. b wR2 = [∑(w(Fo ꢀ Fc2)2/∑w(Fo ) ]
.
2
2 2 1/2
in a pressure-resistant Teflon-sealed Schlenk tube for 7 h. Then the
solvent was removed under reduced pressure, and the residue was
washed with diethyl ether. The remaining solid was recrystallized from
THF/Et2O to give 9c as a red crystalline solid. Yield: 58.2 mg, 50%. Anal.
Calcd for C56H56NO3F3SRu2: C, 62.15; H, 5.22; N, 1.29. Found: C,
62.22; H, 5.05; N, 1.12. 1H NMR (acetone-d6): δ 11.62 (s, 1H,
HC(PhCCPh)(PhCCPh)NPh), 7.68ꢀ6.17 (m, 25H, Ph), 1.66, 1.10
(s, 15H each, Cp*). 13C{1H} NMR (acetone-d6): δ 186.8 (HC-
(PhCCPh)(PhCCPh)NPh), 150.2, 139.7, 137.0, 134.7, 133.2, 132.9,
130.9, 130.8, 130.7, 130.6, 129.9, 129.8, 128.9, 128.7, 127.2, 126.8, 126.2
(Ph), 122.5 (q, J = 320 Hz, CF3SO3), 100.4, 102.4 (C5Me5), 114.9, 98.3,
90.6, 88.7 (HC(PhCCPh)(PhCCPh)NPh), 10.6, 9.3 (C5Me5). FAB-
MS: m/z 934 [M]þ.
X-ray Crystallography. In all cases, crystals were taken from as-
isolated products. A single crystal of each sample was coated with
Paratone-N hydrocarbon oil and mounted on a glass capillary. All
measurements were performed on a Rigaku R-AXIS Rapid imaging
plate detector with graphite-monochromated Mo KR radiation (λ =
0.71069 Å). The frame data were processed using the Rigaku PRO-
CESS-AUTO program,93 and the reflection data were corrected for
absorption with an ABSCOR program.94 The structures were solved by a
direct method (SHELXS 97) and refined on F2 by full-matrix least-
2170
dx.doi.org/10.1021/om1011227 |Organometallics 2011, 30, 2160–2172

Organometallics
ARTICLE
squares methods by using SHELX97.95 Anisotropic refinement was
applied to all non-hydrogen atoms. The vinylic hydrogen atoms in 4e, 8,
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Other hydrogen atoms were placed at calculated positions and treated as
riding models. Thermal ellipsoid plots were drawn with the ORTEP-3
program96 and presented at the 35% probability level. The checkcif
reports for 3a, 4c, 4e, 5, 70, and 9b feature level-A alerts, which are based
on large variations of U(eq) values for carbon atoms in each structure.
Although these alerts suggest incorrect identification of atomic species,
these are in fact due to large thermal motion of some of the Cp* and t-Bu
groups in the structures and do not affect the results of structure
determinations.
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BORDER.100 Wiberg bond orders were calculated using the NBO code
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’ ASSOCIATED CONTENT
S
Supporting Information. Crystallographic information
b
files (CIF) for 2f, 3a, 4c, 4e, 5 (cis isomer), 70, 8, 9a, and 9b;
thermal ellipsoid plots for 4e and 9b; optimized structures and
atomic coordinates. This material is available free of charge via
the Internet at http://pubs.acs.org.
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Commun. 2006, 1328.
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’ AUTHOR INFORMATION
(35) Badiei, Y. M.; Dinescu, A.; Dai, X.; Palomino, R. M.;
Heinemann, F. W.; Cundari, T. R.; Warren, T. H. Angew. Chem., Int.
Ed. 2008, 47, 9961.
(36) Takemoto, S.; Otsuki, S.; Hashimoto, Y.; Kamikawa, K.;
Matsuzaka, H. J. Am. Chem. Soc. 2008, 130, 8904.
(37) Tejel, C.; Ciriano, M. A.; Jimꢀenez, S.; Passarelli, V.; Lꢀopez, J. A.
Inorg. Chem. 2008, 47, 10220.
Corresponding Author
*E-mail: takemoto@c.s.osakafu-u.ac.jp; matuzaka@c.s.osakafu-u.
ac.jp.
’ ACKNOWLEDGMENT
This work was supported in part by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Science,
Sports, and Culture of Japan (No. 21550064 and No. 18033046
Research on Priority Area “Chemistry of Coordination Space”).
We also acknowledge financial support from Mitsubishi Founda-
tion, Ube Foundation, and Toyota Motor Corporation.
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