A reactive Ru-binaphtholate building block with self-tuning hapticity

Article abstract of DOI:10.1021/ja204767a

A versatile Ru-BINO building block is reported, which offers a straightforward entry point into the chemistry of atropisomeric binaphtholate complexes of ruthenium. Reaction of RuCl₂(PPh₃) ₃6a with Tl₂((S)-BINO) affords Ru((S)-BINO)(PPh ₃)₂7 as a mixture of isomers: in 7′, the BINO ligand is bound via η³-CCO, η¹-O′ donors, and in symmetrical 7″, via η³-CCO, η³- O′C′C′ interactions. The bis(enolate) BINO bonding mode in the latter, not previously observed for any metal, underscores the remarkable geometric and electronic flexibility of the binaphtholate moiety. The BINO ligand proves able to stabilize complexes containing as few as two, and as many as four, additional ligands in 7 and its derivatives, enabling a synthetic versatility that contrasts with that of the superficially similar o-catecholate complex Ru(o-cat)(PPh₃)₃. As with the important achiral Ru precursor 6a, complex 7 undergoes facile transformation into a range of products under mild conditions, including acetonitrile, pyridine, and vinylidene derivatives. Single-crystal X-ray structures are reported for three of these complexes: Ru(η³,η³-(S)-BINO)(PPh ₃)₂7″, Ru(η³,η¹-(S)- BINO)(PPh₃)₂(MeCN) 9, and Ru(η³, η¹-(S)-BINO)(PPh₃)(py)₂11. ¹³C{¹H} NMR signatures are proposed for new and known BINO coordination modes (η¹-O, η¹-O′; η¹-C1, η¹-O′; η³-CCO, η³-O′C′C′; η³-CCO, η¹-O′; η⁶-C₆,η¹- O′), as a potential aid to further developments in late-metal BINO chemistry.

Full text of DOI:10.1021/ja204767a

ARTICLE
pubs.acs.org/JACS
A Reactive RuꢀBinaphtholate Building Block with
Self-Tuning Hapticity
Johanna M. Blacquiere, Carolyn S. Higman, Robert McDonald,† and Deryn E. Fogg*
Center for Catalysis Research & Innovation and Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
S Supporting Information
b
ABSTRACT: A versatile RuꢀBINO building block is reported, which offers a straightforward entry point
into the chemistry of atropisomeric binaphtholate complexes of ruthenium. Reaction of RuCl2(PPh3)3 6a
with Tl2((S)-BINO) affords Ru((S)-BINO)(PPh3)2 7 as a mixture of isomers: in 70, the BINO ligand is
bound via η3-CCO,η1-O0 donors, and in symmetrical 700, via η3-CCO,η3-O0C0C0 interactions. The
bis(enolate) BINO bonding mode in the latter, not previously observed for any metal, underscores the
remarkable geometric and electronic flexibility of the binaphtholate moiety. The BINO ligand proves able to stabilize complexes
containing as few as two, and as many as four, additional ligands in 7 and its derivatives, enabling a synthetic versatility that contrasts
with that of the superficially similar o-catecholate complex Ru(o-cat)(PPh3)3. As with the important achiral Ru precursor 6a,
complex 7 undergoes facile transformation into a range of products under mild conditions, including acetonitrile, pyridine, and
vinylidene derivatives. Single-crystal X-ray structures are reported for three of these complexes: Ru(η3,η3-(S)-BINO)(PPh3)2 700,
Ru(η3,η1-(S)-BINO)(PPh3)2(MeCN) 9, and Ru(η3,η1-(S)-BINO)(PPh3)(py)2 11. 13C{1H} NMR signatures are proposed for
new and known BINO coordination modes (η1-O,η1-O0; η1-C1,η1-O0; η3-CCO,η3-O0C0C0; η3-CCO,η1-O0; η6-C6,η1-O0), as a
potential aid to further developments in late-metal BINO chemistry.
’ INTRODUCTION
preference to the O,O0-binding prevalent in harder, more oxophilic
metals (see also 4, 5; Chart 1).
The deployment of asymmetric catalysis in pharmaceutical and
agrochemicals manufacturing1,2 will undoubtedly see further ex-
pansion with massive projected increases in the global consumer
population, coupled with increasing pressure on feedstocks. Among
the “privileged” chiral auxiliaries3 central to current asymmetric
catalytic processes, the atropisomeric 1,10-binaphthyl moiety stands
out for its ubiquity and importance as a stereogenic element
within both binaphtholates and their neutral derivatives (e.g.,
BINAP, the phosphoramidites, and MOP ligands). The parent
1,10-binaphtholate (BINO) ligand and its 3,30-functionalized
derivatives have themselves been exploited in transformations
ranging from conjugate addition, vinylation, and alkynylation of
CdE functionalities (E = O, N) to FriedelꢀCrafts alkylation and
hydroaminoalkylation, hydroamination/cyclization, and CꢀC
coupling of olefins, including cycloaddition and olefin metathesis
reactions.4ꢀ6
Prominent in much of this chemistry is the hard Lewis acid
character of the catalysts, a reflection of the dominance of early
and mid-transition elements, the lanthanides, and main group
metals. Soft Lewis acids based on BINO complexes of the late
transition metals have the potential to further expand this rich
area of opportunity. Advances in group 10-BINO chemistry,
particularly by the Gagnꢀe group, are notable in this context.7,8
Despite the enormous scope of ruthenium catalysis,9,10 however,
Ru derivatives are very recent. The first example, 18-electron
Ru((R)-BINO)(p-cymene) 1, was reported by Yao, Li, and co-
workers in 2008,11 while our group recently described RuꢀBINO
catalystsrelevanttoasymmetric olefin metathesis(2, 3; Chart 1).12
Both 1 and 2 exhibit multidentate chelation of the BINO ligand, in
The present work began with the search for a RuꢀBINO
building block that might retain the versatility of the important
precursor complex RuCl2(PPh3)3 6a (one of the most widely used
starting materials in ruthenium chemistry)13 within atropisomeric
Ruꢀbinaphtholate complexes. One aspect of this versatility arises
from the capacity of 6a to undergo partial functionalization or
ligand exchange, with retention of a stabilizing phosphine group
as required. An open question at the outset was whether reaction
of 6a with BINO would terminate at a very stable piano-stool
complex, as found on treating RuHCl(PPh3)3 6b with the BINO
derivative BINOP (see 5, Chart 1),14,15 or whether reactive, coordi-
natively unsaturated structures might be attainable. Here, we
report the successful synthesis of Ru((S)-BINO)(PPh3)2 7, as a
mixture of isomers in which the BINO ligand is bound via oxygen
and an η3-CCO enolate moiety, or via a bisꢀenolate interaction;
we describe the sensitive response of the BINO binding mode to
the coordination environment at the metal, and the resulting
capacity of 7 to support both exchange of the ancillary ligands and
installation of additional reactive functionalities atthe metal center.
’ RESULTS AND DISCUSSION
Installation of the BINO ligand on the ruthenium framework of
6a proceeds in high yield at ambient temperature. Thus, addition
of Tl2((S)-BINO)16 to a purple suspension of 6a in THF at 24 °C
caused an immediate color change to pink and deposition of
TlCl. Formation of Ru((S)-BINO)(PPh3)2 7 (Scheme 1a) was
Received: May 24, 2011
Published: August 15, 2011
r
2011 American Chemical Society
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Chart 1. Established Coordination Modes for Complexes of
BINO and (See 5) BINOPa
Figure 1. Charge-transfer MALDI mass spectrum of 7 (pyrene matrix).
Inset: Simulated (top) and observed (bottom) isotope patterns.
interconversion occurs on the 2.2 s time-scale of the T1 for 70, as
indicated by spin saturation transfer experiments (kexchange = 0.29 sꢀ1),
although a rigorously quantitative interpretation of the rate of chemical
exchange is hampered by the potential for NOE effects.21
The parent systems 6 are classic ruthenium precursors for
which phosphine dissociation gives entry to a rich catalytic and
coordination chemistry,13 including high-yield routes to cataly-
tically important9a,c,10 alkylidene, allenylidene, and vinylidene
derivatives. The utility of the catecholate analogue Ru(η1,η1-O,
O0-O2C6H4)(PPh3)3 8 (Scheme 1b) is limited in comparison,
this complex resisting, for example, transformation into vinyli-
dene or benzylidene derivatives.18 To examine the influence of
the BINO ligand on reactivity, we undertook treatment of 7 with
acetonitrile and pyridine, as well as with tert-butylacetylene: the
corresponding reactions of 6a afford RuCl2(PPh3)2(L)n deriva-
tives (L = py, MeCN),22 and vinylidene complex RuCl2(PPh3)2-
(dCdCHtBu),23 respectively.
aBINOP = 1-diphenylphosphino-1,10-binaphthyl-10-olate; IMes = N,
N0-bis(mesityl)imidazol-2-ylidene; py = pyridine. Numbering shown for
one naphtholate ring; corresponding nuclei on the second bear a prime
label. For simplicity, BINO binding is described in the text using the
labels depicted. Thus, 2 is referred to as an η3,η1-BINO complex, rather
than an η3-C,C,O-BINO-kO structure. The asterisk in the label η1*
indicates the η1-C1 coordination mode in 4.7j
Scheme 1. Reactions of 6a with (a) Binaphtholate and (b)
o-Catecholate Ion
Acetonitrile Derivatives. Addition of neat MeCN to solid pink
7 resulted in immediate formation of an orange suspension, from
which Ru(η3,η1-(S)-BINO)(PPh3)2(MeCN) 9 (Scheme 2a) was
isolated as a dark pink solid in ca. 70% yield. Multinuclear NMR
analysis in CD2Cl2 confirmed the presence of two, cis-disposed
phosphine ligands (δP 49.1, 48.3 ppm; 2JPP = 22 Hz), and a single
nitrile ligand (δC 120.3 ppm, δH 1.37 ppm). While X-ray analysis of
crystals grown from THFꢀEt2O suggests an η2-interaction be-
tween the Ru center and the C2ꢀO1 bond (Figure 2b), the 15 Hz
magnitude of the C1ꢀP coupling constant, as well as the 13C NMR
chemical shift data (vide infra), provide convincing evidence for an
η3,η1-BINO structure in solution. The difference may reflect crystal
packing effects.
quantitative within 1 h: this product was isolated in 82% yield by
filtration and reprecipitation from THF/hexanes. Charge-trans-
fer MALDI-TOF MS17 (Figure 1) and combustion analysis of
7 are consistent with the proposed formulation. In comparison,
the corresponding reaction of 6a with catecholate18 terminates
in tris-phosphine complex 8 (Scheme 1b). The difference in
coordination mode and number is an early indicator of the
structural and electronic versatility that proves a hallmark of the
BINO ligand in this chemistry.
Addition of CD3CN to benzene solutions of 7 improves the
solubility of the products and triggers coordination of a second
acetonitrile ligand via slippage from η3,η1- to η1,η1-BINO binding.
The equivalence of the PPh3 ligands, which give rise to a well-
resolved 31P{1H} NMR singlet at 45.5 ppm (1:2 CD3CNꢀ
C6D6), is consistent with symmetrical Ru(η1,η1-(S)-BINO)-
(PPh3)2(MeCN)2 10. This is assigned as the sterically favored
31P{1H} NMR analysis of 7 reveals a 1:4 mixture of isomers in
CD2Cl2 at room temperature (70, 43.5 ppm; 700, 56.9 ppm; both
singlets). Neither complex exhibits the extremes of BINO
coordination seen in Chart 1: that is, binding through solely
the oxygen sites (see 3) or via an η6-arene,η1-O0 interaction
analogous to the binding mode present in 5.19 Instead, we assign
the minor, higher-field signal to isomer 70, containing an
unsymmetrically η3,η1-bound BINO ligand, on the basis of its
resolution into an AB pattern at slightly lower temperatures
3
trans-PPh3 isomer, given the absence of JPꢀC2 coupling. At-
tempts to precipitate 10 yield only 9, indicating facile exchange
between these five- and six-coordinate species.
Pyridine Derivatives. Reaction of 7 with pyridine, in contrast,
gives bis- and tris-pyridine derivatives Ru(η3,η1-(S)-BINO)(PPh3)-
(py)2 11 and Ru(η1,η1-(S)-BINO)(PPh3)(py)3 12, a reflection of
the higher donor ability of this ligand, relative to acetonitrile
(Gutmann donor number 33.1, vs 14.1 kcal molꢀ1).24 In neat
pyridine-d5, 7 is rapidly and completely converted into orange 12
(Scheme 2b), the 31P{1H} NMR singlet for the latter (56.0 ppm)
integrating 1:1 versus free PPh3. Only minor amounts of 12 were
isolated, however, when the pyridine solution was stripped of solvent,
subjected to azeotropic removal of free pyridine with hexanes, and
2
(15 °C: 43.7, 43.3 ppm; JPP = 19 Hz), as well as detailed
13C{1H} NMR analysis. NMR signatures associated with this
and other BINO coordination modes are discussed in a subse-
quent section. The downfield singlet in the 31P{1H} NMR
spectrum (the sole peak observed at 60 °C)20 is due to complex
700, containing a novel, η3,η3-BINO binding mode: the nature of
this interaction was confirmed by X-ray crystallographic
(Figure 2a) and 13C{1H} NMR analysis. At 40 °C in C6D6,
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Figure 2. Perspective views of (a) Ru(η3,η3-(S)-BINO)(PPh3)2 700, (b) Ru(η3,η1-(S)-BINO)(PPh3)2(MeCN) 9, and (c) Ru(η3,η1-(S)-BINO)-
(PPh3)(py)2 11, showing the labeling scheme for key atoms. Non-hydrogen atoms are represented by Gaussian ellipsoids at the 50% probability level.
For clarity, hydrogen atoms are not shown, solvate molecules present for 9 THF and 11 Et2O 0.25THF are omitted, and phosphine phenyl groups are
3
3
3
truncated to the ipso-carbons.
proved inert to such treatment.18 Complex 7, in comparison,
underwent an immediate color change from red to dark purple,
with quantitative conversion to Ru(η3,η1-(S)-BINO)(PPh3)2-
(dCdCHtBu) (13; Scheme 2c). The product was isolated by
precipitation from THFꢀhexanes, albeit in only 40% yield, due
to its high solubility. The structure depicted in Scheme 2c is
supported by NMR, IR, and combustion analysis. Retention of
two inequivalent phosphine ligands is evident from the AB pattern
Scheme 2. Reactions of 7 with (a) Acetonitrile, (b) Pyridine,
and (c) tert-Butylacetylenea
2
in the 31P{1H} NMR spectrum (64.4, 38.3 ppm; JPP = 27 Hz),
while the vinylidene ligand gives rise to a strong, diagnostic infrared
ν(CdC) band at 1633 cmꢀ1, as well as the expected NMR corre-
lations between the CH multiplet at 3.08 ppm and the RudC and
13
C(CH3)3 signals at 347.2 and 0.72 ppm, respectively (1Hꢀ C
1
1
HMBC; Hꢀ H COSY). A dynamic process operative at room
temperature obscures the 13C NMR signals above 135 ppm, and
hence unequivocal assignment of the coordination mode, as this is
the region occupied by the critical C2/C20 signals. Low-temperature
analysis is consistent with an η3,η1-BINO coordination mode (see
next section), albeit with significant electronic perturbation at C1,
relative to other such complexes.25 Complex 13 differs from the
other examples studied in containing a strongly π-acidic vinylidene
ligand, as discussed below.
a For clarity, exchange reactions between η3 and η1 sites in 11 (see text)
are omitted.
treated with pentane to precipitate the product. The resulting
fine orange suspension consisted principally of 11 (ca. 20% 12
present; 76% total yield). The proportion of 12 decreases further
on washing the filtrand with pentane.
NMR Signatures for BINO Coordination Modes. BINO, like
its important derivative BINAP and related ligands,26 is evidently
characterized by great flexibility and variety in its coordination to
late-metal centers. To facilitate future development, we sought to
establish NMR markers for the different BINO coordination
modes. As the NMR values for the key 13C nuclei have not been
routinely reported, the chemical shift ranges proposed below must
be regarded as preliminary: whether they indeed correlate directly
with coordination mode will become clearer as the number of
crystallographically and spectroscopically characterized examples
expands, but such a correlation would greatly aid in structural
assignment where X-ray analysis is inconvenient or infeasible. In
general most sensitive to changes in naphtholate binding are the
chemical shifts of C2/C20 and C1/C10 (Figure 3a).27 The former
appear generally more diagnostic, as discussed below. 13C{1H}
NMR signals for these ipso carbons were most readily located via
1H-detected HMBC experiments; a “road map” for assignment of
these and the remaining BINO carbons is given in the Supporting
Information.
Solutions of the initially obtained crude product in CD2Cl2
exhibit a broad 31P{1H} NMR singlet due to 11, accompanied by
a sharp singlet for 12 (58.3 and 56.1 ppm, respectively; 20% 12).
The breadth of the signal for 11 we attribute to dynamic
averaging between η3-enolate and η1-O sites at room tempera-
ture, a process observed previously with 1,11 and proposed for
4.7j At ꢀ20 °C, the peak sharpens (ω1/2 diminishes from 45 to
5 Hz), and the corresponding 13C{1H} NMR spectrum suggests
an η3,η1-BINO structure, in which the PPh3 ligand lies trans to
C1, as judged from the large PꢀC coupling constant of 19 Hz.
Such a bonding mode is indeed evident on X-ray analysis of
crystals of 11 that deposited from THFꢀEt2O (Figure 2c). On
cooling the NMR sample further, to ꢀ40 °C, a new 31P{1H}
NMR singlet emerges at 48.3 ppm (ca. 20% of total integration):
this may plausibly be due to the reduced-hapticity isomer Ru-
(η1,η1-(S)-BINO)(PPh3)(py)2, but 13C{1H} NMR confirmation
is precluded by the relatively low abundance of this species.
Vinylidene Derivative. A final experiment was directed at
examining the ease of converting 7 into a vinylidene complex.
Reaction of 6a with tert-butylacetylene affords RuCl2(PPh3)2-
(dCdCHtBu),23 as noted above, while catecholate complex 8
For η1-O,η1-O0-BINO complexes (e.g., 3a, 3b, 10, 12; Table 1),
the aryloxy carbons C2 and C20 appear at ca. 168 ppm, and C1/C10 at
ca. 126 ppm. These locations appear relatively insensitive to changes
in the NMR solvent (Table 2). For the η3-CCO, η1-O0-BINO
complexes (e.g., 1, 2, 70, 9, 11), the chemical shift for C20 in the
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η1-bound ring shows minimal change, appearing at ca. 172 ppm.
That for C10 moves 10 ppm upfield, however (to ca. 115 ppm),
a reflection of the sensitivity of C10 to the enolate environment
at the immediately adjacent C1 nucleus. The η3-CCO carbons
themselves can exhibit more dramatic upfield shifts, depending on
the extent of shielding by the electrons circulating in the enolate π-
system: an average value of 148 ppm is seen for C2 and 97 ppm for
C1. Variable back-donationresults ina rather broadrange of values
for C2 ((6 ppm) and, especially, C1 ((12 ppm), asshown in blue
and red, respectively, in Figure 3a. Omitted from these ranges are
the values for 13, which is anomalous within this series in
containing a highly π-acidic vinylidene ligand (a π-acceptor
comparable to CO).28 This is expected to limit shielding of the
η3-enolate nuclei: indeed the signal for C1 appears at ca. 126 ppm,
a location typical for η1-bound BINO, although C2 is less affected.
Within the ranges indicated for the more typical η3-enolates
appear the corresponding signals for both naphtholate rings of
the η3,η3-BINO complex 700 (C2/C20, 145 ppm; C1/C10, 93
ppm).29 For phosphine derivatives, 3JCP splitting of the C1/C10
signal(s) is valuable in confirming the presence of a direct
RuꢀC1 interaction, although the dependence on the dihedral
angle means that negative evidence is less reliable.
The rarer η1-C1,η1-O0 coordination mode exhibits a diagnos-
tic ketone signal for C2 (196 ppm for complex 4),7g,j although the
82 ppm location for C1 is not far from the lower end of the range
for η3,η1-BINO complexes. Finally (and in contrast to the
examples above, all of which can be assigned from the combined
C1/C10 and C2/C20 chemical shifts), the η6,η1-binding mode in
complex 5 is distinguishable from η3,η1-BINO binding only once
a ca. 30 ppm upfield shift14 for both C3 and C4 is also taken into
consideration, as illustrated in Figure 3b.
’ CONCLUSION
The BINO ligand offers a powerful source of chirality that has
been exploited with great success in asymmetric catalysis by hard
Lewis acidꢀbase complexes. Its incorporation into soft late-metal
complexes, a challenge of sustained interest, is here expanded to a
versatile rutheniumꢀbinaphtholate building block. The remark-
able geometric and electronic flexibility of the binaphtholate ligand
is demonstrated by its capacity to coordinate in modes ranging
from η1-O,η1-O0 to η1-O,η3-C0C0O0 and, in the extreme, η3-CCO,
η3-C0C0O0 binding, in addition to others previously established.
13C{1H} NMR signatures for each binding mode are suggested on
the basis of current data, as an aid to structural assignment;
the small sample sets, however (particularly for the singular η3,
η3-BINO complex 700), means that the proposed correlations of
BINO coordination modes with chemical shift ranges should be
Figure 3. 13C NMR signatures for different BINO coordination modes.
(a) Chemical shift ranges for C2/C20 (blue) and of C1/C10 (red), as in
Table 1; dashed lines correspond to the “prime” nuclei.27 The asterisk in the
label η1* indicates the η1-C1 coordination mode in 4.7g,j (b) Supplementary
chemical shifts of C3/C4 (black), where assignment on the basis of
(a) alone is ambiguous.
Table 1. 13C{1H} NMR Ranges Associated with Different BINO or (for 5) BINOP Coordination Modes (See Also Figure 3)a,27
entry
coord. mode
compd
C1
C2
C10
C20
ref
1
2
3
4
5
η1,η1
η3,η1
η3,η3
η6,η1
η1,η1*
3a, 3b, 10, 12
1, 2, 70, 9, 11
700
5b
4
126 ( 2
97 ( 12
168 ( 4
126 ( 2
115 ( 2
169 ( 1
172 ( 2
144.7
Table 2
Table 2
this work
14
148 ( 6
144.7
93.2 (t, 2JCP = 4 Hz)
93.2 (t, 2JCP = 4 Hz)
c
c
83.0
82.4
155.6
ꢀ
ꢀ
c
c
195.5 (d, 6 Hz)
ꢀ
ꢀ
7g,7j
a Values at ambient temperature, except 11ꢀ12 (20% 12; 253 K, CD2Cl2); 13 (213 K); 1(210 K). Values for700, 5, 4 in CD2Cl2; for others, see Table 2. Values
for vinylidene complex 13 are anomalous (see text) and are omitted. Peaks are singlet multiplicity, unless otherwise specified. (*) indicates the η1-C1
coordination mode in 4. b Ranges for C3/C4: 95ꢀ97 ppm, versus 124ꢀ135 for these resonances in η3,η1-BINO complexes. c Assignment not reported.
Table 2. 13C{1H} NMR Data for Individual Compounds Grouped into Entries 1 and 2 of Table 1a
coord. mode compd
solvent
C1
C2
C10
C20
ref
η1,η1
3a
3b
10
12
12
1
CD2Cl2
CD2Cl2
124.2
123.9
164.0
164.0
168.9
171.0
169.8
141.5
123.9
123.9
127.4
127.8
170.1
170.3
168.9
169.7
168.7
170.9
12
12
b
CD3CNꢀC6D6 (1:2) 127.4
C5D5N
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
128.1
b
not located
not located
114.0
b
η3,η1
85.0
11
2
70
95.6 (d, 2JCP = 11 Hz)
154.1 (d, 2JCP = 3 Hz) 116.8
114.2 (d, 3JCP = 2 Hz) 170.4 (d, 3JCP = 5 Hz)
106.4 (d, 2JCP = 15 Hz) 143.3 (d, 2JCP = 2 Hz) 115.2 (d, 3JCP = 1 Hz) 172.1 (d, 3JCP = 5 Hz)
174.1 (d, 3JCP = 5 Hz) 12
109.1 (d, 2JCP = 16 Hz) 143.1
b
b
b
b
9
11
13
97.6 (d, 2JCP = 19 Hz)
125.6 (t, 2JCP = 4 Hz)
143.5
113.8
116.0
174.4 (d, 3JCP = 5 Hz)
148.0 (t, 2JCP = 4 Hz)
162.0
a For conditions, see footnote to Table 1. b This work.
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regarded as preliminary. Importantly, these BINO enolates are
labile; η3-coordination provides a source of coordinative stabiliza-
tion where required, but does not impede binding of additional
ligands at the metal center. Complexes containing as few as two,
and as many as four, additional ligands are thus accessible. The
chemistry of Ru(BINO)(PPh3)2 7 described above aligns well
with that of the important, achiral ruthenium precursor RuCl2-
(PPh3)3 6a, and compares favorably with the more circumscribed
scope of its close relative Ru(o-cat)(PPh3)3. Complex 7 thus offers
a potentially powerful and convenient entry point into the chemistry
of atropisomeric binaphtholate complexes of ruthenium.
observed in CDCl3, but decomposition over the time-scale required for
2D NMR analysis prevents characterization in this solvent.) Signals for 70
were assigned by spectral subtraction of resonances for 700 from the room-
temperature spectrum of the two isomers in CD2Cl2. For the BINO
numbering scheme, see Chart 1. The majority of the BINO signals in these,
as well as the other new complexes, could be assigned using the roadmap
provided in the Supporting Information.32
Ru(η3,η3-(S)-BINO)(PPh3)2 700. 31P{1H} NMR (121.4 MHz,
1
CD2Cl2): δ 56.9 (s), 56.5 ppm in CDCl3. H NMR (CD2Cl2, 500.1
MHz): δ 7.38 (m, 4H, H5 and H6), 7.34 (d, 3JH4H3 = 9.3 Hz, 2H, H4),
7.26 (m, 2H, H7), 7.22ꢀ7.06 (m, 10H, Ar), 6.91 (overlap; 28H, Ar;
includes H8 of 700 and H30, H60 of 70), 6.44 (d, 3JH3H4 = 9.3 Hz, 2H, H3).
13C NMR (CD2Cl2, 125.6 MHz): δ 144.7 (s, C2), 137.8 (s, C8a), 137.4
(s, C4), 134.6 (d, JCP = 10 Hz, Ph), 134.1 (br, Ph), 133.8 (d, JCP = 10 Hz,
Ph), 132.3 (d, JCP = 10 Hz, Ph), 132.2 (d, JCP = 4 Hz, Ph), 130.9 (s, C4a),
’ EXPERIMENTAL SECTION
General. Reactions were carried out at room temperature (24 °C)
under N2 using standard Schlenk or glovebox techniques. Dry, oxygen-
free solvents were obtained using a Glass Contour solvent purification
system and were stored over Linde 4 Å molecular sieves. Pyridine was
distilled over sodium benzophenone ketyl and was stored over activated
sieves (Linde 4 Å) in an amber bottle in the glovebox. CDCl3 was
distilled over CaH2 and stored over activated sieves (Linde 4 Å). 1,
10-Binaphthol ((S)-BINOL; 99% optical purity; Strem) and pyrene,
anhydrous CD2Cl2, and pyridine-d5 (all Aldrich) were used as received.
RuCl2(PPh3)330 was prepared by literature methods. NMR spectra were
recorded on Bruker Avance 300 and Avance 500 spectrometers, at 296 K
unless otherwise specified. Chemical shifts are reported relative to TMS
(13C, 1H) or 85% external H3PO4 (31P) at 0 ppm and were referenced to
the carbon or residual proton signal of the deuterated solvent. Micro-
analyses were carried out by Guelph Chemical Laboratories (Guelph,
ON) and X-ray analyses by Dr. Robert McDonald of the University
of Alberta X-ray Crystallography Laboratory. Charge-transfer (CT)
MALDI-TOF mass spectra were collected using a Bruker Daltonics
Omniflex MALDI-TOF mass spectrometer coupled to an MBraun
glovebox, as previously described.17
130.2 (d, JCP = 1 Hz, Ph), 129.4 (s, C5), 129.2 (br, Ph), 128.1 (d, JCP
=
6 Hz, Ph), 128.0 (d, JCP = 6 Hz, Ph), 127.4 (s, C7), 127.3 (m, Ph), 124.9
(s, C8), 124.5 (s, C6), 124.3 (s, C3), 93.2 (t, 2JC1P = 4 Hz, C1).
Ru(η3,η1-(S)-BINO)(PPh3)2 70 (20%). Chemical shifts are given
for key peaks only; extraction of most multiplicities and integration
values was hampered by overlap with the signals due to the major
product 700. 31P{1H} NMR (121.4 MHz, CD2Cl2): 43.5 (s). At 288 K:
43.7 (d, 2JPP = 19.4 Hz), 43.3 (d, 2JPP = 19.4 Hz). 1H NMR (CD2Cl2,
500.1 MHz): δ 8.17 (d, 3JH4H3 = 9 Hz, H4), 7.89 (d, 3JH5H6 = 8 Hz, H5),
7.55 (H50), 7.29 (H3), 7.45 (H40), 7.27 (H6), 6.88 (H30), 6.86 (H60),
3
6.70 (H7 and H70), 6.57 (H8), 5.96 (d, JH8 H7 = 9 Hz, H8 ). 13C NMR
(CD2Cl2, 125.6 MHz): 170.4 (d, 3JCP = 5 Hz, C20), 143.1 (s, C2), 141.3 (d,
3JCP = 3 Hz, C8a), 135.1 (s, C4), 133.4 (s, C8a0), 129.6 (s, C8), 128.9
(s, C40), 128.8 (s, C4a), 128.6 (s, C5), 128.2 (s, C50), 127.4 (s, C7), 127.2
(s, C4a0), 124.9 (s, C70), 124.6 (s, C6), 124.4 (s, C3), 124.2 (s, C80), 123.9 (s,
C30), 119.8 (s, C60), 114.2 (d, 3JCP =2Hz, C10), 109.1 (d, 3JCP =16Hz, C1).
Synthesis of Ru(η3,η1-(S)-BINO)(PPh3)2(MeCN) 9. Addition
of acetonitrile (0.5 mL) to solid 7 (151 mg, 0.166 mmol) resulted in an
immediate color change from pink to orange, and complete conversion
to 9 (31P{1H} NMR analysis). The suspension was stirred for 5 min,
then stripped of solvent, treated with cold hexanes (2 mL), and chilled to
ꢀ35 °C. The fine solid was isolated by pipetting off the supernatant
and was dried under vacuum. Yield: 120.5 mg (76%). Anal. Calcd for
C58H45NO2P2Ru: C, 73.25; H, 4.77; N, 1.47. Found: C, 72.97; H, 4.61;
0
0
0
Synthesis of Tl2((S)-BINO). Addition of (S)-BINOL (862 mg,
3.01 mmol) to a stirred solution of TlOEt (1.652 g, 6.628 mmol) in Et2O
(10 mL) afforded a pale yellow precipitate. The suspension was stirred at
room temperature for 15 h, after which the solid was isolated by filtration
and washing with Et2O (2 mL). Yield 87%. Caution: Tl salts are toxic31
and must be handled using appropriate protection and secondary
containment; wastes and contaminated material must be disposed of
in accordance with federal regulations.
N, 1.20. Single crystals of 9 THF deposited from THF by vapor diffusion
3
of diethyl ether (Et2O) at 24 °C. NMR analysis in CD2Cl2 revealed only
2
signals for 9. 31P{1H} NMR (CD2Cl2, 121.4 MHz): δ 49.1 (d, JPP
=
22 Hz), 48.3 (d, 2JPP = 22 Hz). 1H NMR (CD2Cl2, 500.1 MHz): δ 8.00
Synthesis of Ru((S)-BINO)(PPh3)2 7. A suspension of Tl2
((S)-BINO) (326 mg, 0.470 mmol) and RuCl2(PPh3)3 6a (450 mg,
0.470 mmol) in 12 mL of THF was stirred for 1 h at 24 °C, over
which time it turned from purple to pink. 31P{1H} NMR analysis
indicated complete reaction. As the suspension was too fine to filter
off, the solvent was stripped off under vacuum. The residue was
taken up in benzene, filtered through Celite, then glass-fiber filter
paper, and the Ru product was washed through with benzene. The
filtrate was stripped to dryness to give a dark residue, which was
redissolved in THF (ca. 0.5 mL), treated with hexanes (6 mL), and
chilled to ꢀ35 °C. The air-sensitive red-pink product was filtered
off, washed with cold hexanes (3 mL) and cold 3:1 hexanesꢀEt2O
(3 ꢁ 1 mL), and then dried. Yield: 351 mg (82%). CT-MALDI MS
(pyrene matrix), m/z: [7]+• 910.2 (simulated: 910.2). Anal. Calcd
for C56H42O2P2Ru: C, 73.92; H, 4.65. Found: C, 74.23; H, 4.38.
The product contained a mixture of 700 and 70 (ratio 4:1 in CD2Cl2),
the spectroscopic data for which are separated for convenience
below. X-ray quality crystals of 700 deposited from THF by vapor
diffusion of hexanes at 24 °C. NMR signatures for the novel η3,
3
3
(d, JH4H3 = 9.5 Hz, 1H, H4), 7.81 (d, JH5H6 = 7.5 Hz, 1H, H5),
3
7.57ꢀ7.51 (m, 8H, H50 and Ph), 7.40 (d, JH4 H3 = 8.5 Hz, 1H, H40),
7.28ꢀ7.25 (m, 3H, Ar), 7.19 (d, 3JH3H4 = 9.0 Hz, 1H, H3), 7.17 (m, 1H,
H6), 7.14ꢀ7.11 (m, 10H, Ph), 6.92ꢀ6.89 (m, 7H, H30 and Ph), 6.80
0
0
(m, 1H, H60), 6.66 (m, 1H, H70), 6.62 (m, 1H, H7), 6.58 (d, 3JH8H7 = 5.0
Hz, 1H, H8), 6.55ꢀ6.51 (m, 6H, Ph), 5.91 (d, 3JH8 H7 = 8.5 Hz, 1H, H8 ),
0
0
0
1.37 (s, 3H, CH3CN). 13C NMR (CD2Cl2, 125.6MHz):δ 172.1 (d, JCP
=
5 Hz, C20), 143.3 (d, JCP = 2 Hz, C2), 142.3 (d, JCP = 2 Hz, C8a), 134.8
(s, C8a0), 134.65 (d, JCP = 8.8 Hz, Ph), 133.8 (d, JCP = 10.0 Hz, Ph), 133.1
(s, C4), 129.9 (s, C3), 129.4 (s, C8), 128.8 (s, C4a), 128.7 (s, C40), 128.3
(s, C5), 127.9 (m, C50 and Ph), 126.9 (s, C7), 126.8 (s, C4a0), 124.6
(s, C70), 124.5 (s, C30), 123.9 (s, C80), 123.3 (s, C6), 120.3 (s, CH3CN),
118.9 (s, C60), 115.2 (d, 2JCP = 1 Hz, C10), 106.4 (d, 2JCP = 15 Hz, C1),
3.41 (s, CH3CN). IR (Nujol): ν(CtN) 2263 cmꢀ1 (w).
In probe reactions, 7 (ca. 10 mg) was dissolved in 1:2 CD3CN:C6D6
and analyzed (31P{1H} NMR). Solely bis-nitrile, η1,η1-BINO complex
10 was observed; at lower proportions of CD3CN, signals for 9 emerged.
Poor solubility precluded analysis in neat CD3CN.
η3-BINO coordination mode in 700 were established from 1Hꢀ C
Ru(η1,η1-(S)-BINO)(PPh3)2(MeCN)2 10. 31P{1H} NMR (1:2
CD3CN:C6D6, 121.4 MHz): δ 45.5 (s). 1H NMR (1:2 CD3CN:C6D6,
500.1 MHz): 7.56 (d, 3JH5H6 = 8 Hz, 2H, H5), 7.45ꢀ7.35 (m, 13H, Ph),
13
HMBC spectra measured at 60 °C, to suppress signals for 70. (Both
isomers are generally present, including at ꢀ80°C in C7D8; solely 700 is
14058
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Journal of the American Chemical Society
ARTICLE
Table 3. Crystallographic Collection Parameters for 700, 9 THF, and 11 Et2O 0.25THF
3
3
3
700
9 THF
11 Et2O 0.25THF
3
3
3
CCDC no.
empirical formula
color, shape
formula weight
temp (K)
796872
796870
796871
C56H42O2P2Ru
red, prism
909.91
C62H53NO3P2Ru
orange, plate
1023.06
C53H49N2O3.25PRu
orange, prism
897.98
173(2)
173(2)
173(2)
wavelength (Å)
crystal system
space group
crystal size (mm)
a (Å)
0.71073
0.71073
0.71073
orthorhombic
P212121 (No. 19)
0.14 ꢁ 0.13 ꢁ 0.10
13.0968 (6)
14.0641 (7)
23.0032 (11)
90
orthorhombic
P212121 (No. 19)
0.44 ꢁ 0.11 ꢁ 0.03
13.1015 (5)
13.4592 (5)
28.5044 (10)
90
orthorhombic
P21212 (No. 18)
0.43 ꢁ 0.25 ꢁ 0.24
18.0557 (4)
19.4773 (5)
12.7568 (3)
90
b (Å)
c (Å)
R (deg)
β (deg)
90
90
90
γ (deg)
90
90
90
V (Å3)
Z, calcd density (g/cm3)
4237.1 (4)
4, 1.426
5026.3 (3)
4, 1.352
4486.26 (19)
4, 1.330
μ (mmꢀ1
)
0.490
0.424
0.431
F(000)
1872
2120
1864
θ range for data collectn
2.29° < θ < 24.94°
ꢀ16 e h e 16
ꢀ17 e k e 17
ꢀ28 e l e 28
34 014/8676 (Rint = 0.0496)
Gaussian integration (face-indexed)
0.9535ꢀ0.9323
Patterson/structure expansion
(DIRDIF-2008)
1.43° < θ < 25.69°
ꢀ15 e h e 15
ꢀ16 e k e 16
ꢀ34 e l e 34
37 705/9548 (Rint = 0.0785)
1.54° < θ < 27.51°
ꢀ23 e h e 23
ꢀ25 e k e 25
ꢀ16 e l e 16
limiting indices
reflections collected/unique
absorption correction
40 159/10 315 (Rint = 0.0195)
max, min transmission
structure solution method
0.9891ꢀ0.8355
Patterson/structure expansion
(DIRDIF-2008)
9548/10/611
0.9044ꢀ0.8377
direct methods (SHELXS-97)
data/restraints/params
GOF (S)a
8676/0/550
10 315/3/528
1.083
1.027
1.023
final R indices
R1b [Fo2 g 2σ(Fo2)] wR2 (all data)
R1 = 0.0268
R1 = 0.0380
R1 = 0.0316
wR2 = 0.0985
1.028 and ꢀ0.358
wR2 = 0.0561
wR2 = 0.0812
largest diff peak and hole (e Åꢀ3
)
0.328 and ꢀ0.316
0.650 and ꢀ0.392
2
2
2
a S = [∑w(Fo ꢀ Fc2)2/(n ꢀ p)]1/2 (n = number of data; p = number of parameters varied; w = [σ2(Fo ) + (0.0232P)2 + 0.7848P]ꢀ1, where P = [max(Fo ,
0) + 2Fc2]/3). b R1 = ∑||Fo| ꢀ |Fc||/∑|Fo|; wR2 = [∑w(Fo ꢀ Fc2)2/∑w(Fo )]1/2
.
2
4
7.20 (d, 3JH4H3 = 9 Hz, 2H, H4), 7.1ꢀ6.85 (m, 30H, Ar; includes H8 at
from THF by vapor diffusion of Et2O at 24 °C; combustion analysis was
carried out on the crushed and dried crystals. Anal. Calcd for C48H37N2O2-
PRu: C, 71.54; H, 4.63; N, 3.48. Found: C, 71.26; H, 4.37; N, 3.15.
3
7.00 (d, JH8H7 = 8 Hz)), 6.79 (m, 2H, H7), 6.71 (m, 2H, H6), 6.12
3
(d, JH3H4 = 9 Hz, 2H, H3), 1.35 (m, 3H, CH3CN). 13C{1H} NMR
1
Ru(η3,η1-(S)-BINO)(PPh3)(py)2 11 (Diagnostic 31P and H
(1:2 CD3CN:C6D6, 125.6 MHz): δ 168.9 (s, C2), 135.9 (s, C8a), 134.7
(m, Ph), 129.1 (s, C3), 128.4ꢀ127.6 (overlap of residual C6D5H, Ph,
BINO: within this range, C4a (128.3) and C5 (127.6) located by
correlation experiments), 127.4 (s, C1), 126.8 (s), 125.4 (s, C8),
125.0 (br s, C4), 123.9 (s, C7), 119.3 (s, C6), 116.9 (s, CH3CN), 0.3
(s, CH3CN).
NMR Signals). 31P{1H} NMR(CH2Cl2 + 20 μLofC6D6 for lock, 121.4
1
MHz, 296 K): δ 58.3 (br s). H NMR (CD2Cl2, 500.1 MHz, 253 K):
3
3
δ 8.93 (d, JHH = 5 Hz, 1H, py Ho), 8.75 (d, JHH = 6 Hz, 1H, py),
3
8.58ꢀ8.57 (m, 3H, py), 8.15 (d, JHH = 5 Hz, 1H, py), 7.55ꢀ7.47
(overlapping m, 10H, Ar; includes H50, H7), 7.41 (d, 3JHH = 8 Hz, 1H,
H40), 7.04ꢀ7.00 (overlapping m, 1.5H, Ar; includes H4), 6.94ꢀ6.80
Synthesis of Ru(η3,η1-(S)-BINO)(PPh3)(py)2 11 and Ru-
(η1,η1-(S)-BINO)(PPh3)(py)3 12. Addition of 0.5 mL of pyridine to
7 (93.2 mg, 0.102 mmol) caused an immediate color change from red to
orange. NMR analysis indicated complete conversion to 12. Vacuum
removal of pyridine afforded a gel, to which hexanes (1 mL) were added
with stirring, then pumped off to effect azeotropic removal of pyridine
(3ꢁ). Addition of pentane (1 mL) then gave a fine suspension. A bright
orange solid was filtered off and washed with cold pentane (62 mg, 76%).
31P{1H} NMR analysis revealed 11 and 12 (ratio 4:1; the proportion of 12
decreases with further washing). The spectroscopic data are separated for
convenience below. X-ray quality crystals of 11 Et2O 0.25 THF deposited
(overlapping m, 5H, Ar; includes H30, H60), 6.74ꢀ6.65 (overlapping m,
2H, Ar; includesH70), 6.09 (d, JH3H4 = 9 Hz, 1H, H3), 5.91 (brd, 3JH8 H7
3
0
0
= 9 Hz, 1H, H80), 5.62 (d, J = 5 Hz, 1H, Ar).
Ru(η1,η1-(S)-BINO)(PPh3)(py)3 12 (20%). Only key peaks are
identified; extraction of multiplicities and integration values was ham-
pered by overlap with signals for the major product 11. 31P{1H} NMR
(CH2Cl2 + 20 μL of C6D6 for lock, 121.4 MHz, 296 K): δ 56.1 (s). 1H
NMR (CD2Cl2, 500.1 MHz, 296 K): 6.97 (H4), 6.91 (H40).
Combined 13C{1H} NMR signals for the 11ꢀ12 mixture (CD2Cl2,
125.6 MHz, 253 K): δ 174.4 (d, 3JCP = 5 Hz, C20, 11), 169.7 (s, C2, 12),
3
3
14059
dx.doi.org/10.1021/ja204767a |J. Am. Chem. Soc. 2011, 133, 14054–14062

Journal of the American Chemical Society
ARTICLE
168.1 (s, C20,12), 158.4 (s), 158.0 (s), 157.1 (s), 155.8 (s), 154.7 (br s),
152.8 (s), 149.9 (s), 143.5 (s, C2, 11), 142.0 (s, C8a, 11), 137.2 (s),
136.0 (s), 135.7 (s), 135.2 (s, C8a0, 11), 135.0 (s), 134.8 (s), 134.4 (d,
refined value, as were the CꢀC distances. For 11 Et2O 0.25 THF,
3
3
distances within the THF solvate were restrained to idealized values
during refinement: d(O10SꢀC11S) = 1.46(1) Å; d(C11SꢀC12S) =
d(C12SꢀC12S0) = 1.52(1) Å (C12S0 is related to C12S via the crystal-
lographic 2-fold rotational axis (0, 1/2, z), upon which O10S is located).
CCDC 796872 (700), 796870 (9), and 796871 (11) contain the supple-
mentary crystallographic data for this Article. These can be obtained free
of charge from the Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
J
CP = 9 Hz), 134.2ꢀ134.1 (m), 133.9 (s), 133.7 (d, JCP = 19 Hz), 133.5
(s), 133.4 (s, C4, 11), 133.1 (s), 133.0 (s), 132.1 (s), 132.0 (s), 132.0 (s),
131.9 (s), 129.2 (s), 128.9 (s), 128.6 (d, JCP = 7 Hz), 128.0ꢀ127.9 (m,
includes C40 and C5, 11), 127.8 (s), 127.7 (s, C50, 11), 127.6 (s), 127.4 (s),
127.2 (s), 126.8 (s, C4a, 11), 126.7 (s), 126.69 (s), 126.6 (s), 126.5 (s),
125.9 (s), 125.4 (s, C3, 11), 125.3 (s), 124.7 (s, C70, 11), 124.3 (d, JCP
=
2 Hz, C30, 11), 124.2 (s), 123.8 (s), 123.7 (s), 123.6 (s), 123.5 (s), 123.1
(s), 123.0 (s), 122.6 (s, C80, 11), 122.2 (br s), 119.3 (s), 119.1 (s), 118.7
(s, C60, 11), 113.8 (s, C10, 11), 97.6 (d, 2JCP = 19 Hz, C1, 11).
In Situ Formation of 12 in Pyridine-d5. 31P{1H} NMR
’ ASSOCIATED CONTENT
S
Supporting Information. Details of the approach used to
b
1
assign C{1H} NMR signals for C1/C10 and C2/C20 of the
13
(C6D5N, 121.4 MHz): δ 57.3 (s). H NMR (C6D5N, 500.1 MHz):
δ 7.78ꢀ7.68 (m), 7.58 (br s), 7.50ꢀ7.42 (m), 7.38ꢀ7.34 (m, Ar;
includes H4), 7.31ꢀ7.25 (m, Ar; includes H40), 7.22 (br s), 7.20ꢀ7.04
(m), 6.97ꢀ6.83 (m, Ar; includes H3 and H30). 13C{1H} NMR (C5D5N,
125.6 MHz): δ 171.0 (s, C2), 169.7 (s, C20), 137.9 (s), 137.8 (s), 136.9
(s), 136.3 (s), 136.0 (s), 135.9 (s), 135.1 (s), 134.9 (s), 134.8 (s), 134.2
(s), 134.1 (s), 132.4 (s), 132.3 (s), 132.2 (s), 132.16 (s), 129.2 (s), 129.1
(s), 129.0 (s), 129.01 (s), 128.9 (s), 128.42ꢀ128.35 (m), 128.2 (s),
128.1 (s, C1), 128.06 (s), 127.94ꢀ127.90 (m), 127.8 (s, C10), 127.6 (s),
127.5 (s, C30), 127.1 (s), 126.1 (s), 126.0 (s), 125.8 (s), 125.6 (s), 124.1
(s), 123.9 (s), 123.8ꢀ123.3 (solvent signals overlap; C3 located (123.5)
by correlation experiments), 123.1 (s), 119.8 (s), 119.5 (s).
BINO ligand; NMR spectra, including VT and spin saturation
experiments; and crystallographic information files (CIF). This
material is available free of charge via the Internet at http://
pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
dfogg@uottawa.ca
Present Addresses
†X-ray Crystallography Laboratory, Chemistry Department, Uni-
versity of Alberta, 11227 Saskatchewan Drive NW, Edmonton, AB
T6G 2G2, Canada.
Synthesis of Ru(η3,η1-(S)-BINO)(PPh3)2(dCdCHtBu) 13.
Slow, dropwise addition of tert-butylacetylene (0.08 mL of a 16.6% v/v
solution in C6H6; 2 equiv) to 7 (46.5 mg, 0.051 mmol) in 1 mL of C6H6
caused an immediate color change from red to purple. The reaction was
stirred for 5 min, then stripped, dissolved in THF (0.3 mL), and treated
with hexanes (4 mL) and cooled to ꢀ35 °C. The purple precipitate was
filtered off, washed with cold hexanes, and dried. Yield: 23 mg (45%).
Anal. Calcd for C62H52O2P2Ru: C, 75.06; H, 5.28. Found: C, 75.08; H,
5.41. 31P{1H} NMR (121.4 MHz, CD2Cl2): δ 64.4 (2JPP = 27 Hz), 38.3
(2JPP = 27 Hz). 1H NMR (CD2Cl2, 500.1 MHz, 213 K): δ 8.53 (d, 3JH3H4
= 9 Hz, 1H, H3), 8.01 (d, 3JH4H3 = 9 Hz, 1H, H4), 7.90 (d, 3JH5H6 = 8 Hz,
’ ACKNOWLEDGMENT
This work was funded by NSERC of Canada. NSERC is thanked
for a CGS-D award to J.M.B. and a CGS-M award to C.S.H.
’ REFERENCES
(1) Blaser, H.-U., Federsel, H.-J., Eds. Asymmetric Catalysis on Industrial
Scale, 2nd ed.; Wiley-VCH: Weinheim, 2010.
(2) Blaser, H.-U.; Hoge, G.; Pugin, B.; Spindler, F. Industrial Applica-
tions of Homogeneous Enantioselective Catalysts. In Handbook of Green
Chemistry; Anastas, P. T., Crabtree, R. H., Eds.; Wiley-VCH: Weinheim,
2009; Vol. 1, pp 153ꢀ203.
3
1H, H5), 7.66 (d, 3JH5 H6 = 8 Hz, 1H, H5 ), 7.56 (d, JH4 H3 = 9 Hz, 1H,
H40), 7.45ꢀ7.30 (m, 12H, H6 and Ph), 7.12 (m, 10H, Ph), 7.00 (m, 5H,
H60, H7, H8 and H80), 6.91 (m, 3H, H70), 6.84 (m, 7H, H30 and Ph), 3.08
(br s, 1H, CCHtBu), 0.72 (s, 9H, C(CH3)3). 13C NMR (CD2Cl2, 125.6
MHz, 213 K): δ 347.2 (unresolved, RudCdCHC(CH3)3), 162.0
(s, C20), 148.0 (unresolved m, C2), 135.3 (s, C8a), 134.0ꢀ133.0 (overlap;
Ph and C8a0), 132.7 (s, Ph), 132.3 (s, Ph), 130.8 (s, C3), 130.2 (s, Ph), 128.8
(s,C4a), 128.1 (s, Ph), 127.9 (s, C4), 127.8ꢀ127.1 (overlap; C8, C80,C5, C50
and Ph), 126.6 (m, C40), 126.1 (s, C4a0), 125.6 (t, JCP = 4 Hz, C1), 125.0
(s, C7), 124.3 (s, C70), 123.6 (s, C30), 122.8 (s, C6), 121.1 (s, RudCdCHC-
(CH3)3), 119.8 (s, C60), 116.0 (s, C10), 67.6 (s, RudCdCHC(CH3)3),
30.9 (s, RudCdCHC(CH3)3). IR (Nujol): ν(CdC) 1633 cmꢀ1 (m).
Spin Saturation Transfer Measurement. Complex 7 (10 mg)
was dissolved in C6D6 in an NMR tube. At 40 °C, the 31P{1H} NMR signal
for 700 (57.5 ppm) was saturated by irradiation, and the decrease in intensity
of 70 (40.0 ppm) was measured. The T1 relaxation time for 70 (at 2.2 s) was
established using the inversionꢀrecovery method and analyzing with the
spectrometer T1 routine.
0
0
0
0
0
(3) Yoon, T. P.; Jacobsen, E. N. Science 2003, 299, 1691–1693.
(4) For selected reviews of catalysis via complexes of BINO or 3,
30-derivatized BINO derivatives, see: (a) Najera, C.; Sansano, J. M.; Sa,
J. M. Eur. J. Org. Chem. 2009, 2385–2400. (b) Brunel, J. M. Chem. Rev.
2007, 107, PR1–PR45. (c) Brunel, J. M. Chem. Rev. 2005, 105, 857–897.
(d) Shibasaki, M.; Matsunaga, S. J. Organomet. Chem. 2006, 691, 2089–2100.
(e) Chen, Y.; Yekta, S.; Yudin, A. K. Chem. Rev. 2003, 103, 3155–3211.
(5) Selected recent examples or reviews of CdE bond elaborations
catalyzed by BINO complexes (and, in some cases, organocatalysts).
Conjugate addition: (a) Koripelly, G.; Rosiak, A.; Rossle, M. Synthesis
2007, 9, 1279–1300. Alkynylation or vinylation:(b) Tanaka, K.; Kukita,
K.; Ichibakase, T.; Kotani, S.; Nakajima, M. Chem. Commun. 2011,
47, 5614–5616. (c) Huang, G.; Yang, J.; Zhang, X. Chem. Commun.
2011, 47, 5587–5589. (d) Blay, G.; Cardona, L.; Climent, E.; Pedro, J. R.
Angew. Chem., Int. Ed. 2008, 47, 5593–5596. Other nucleophilic
additions:(e) DeBerardinis, A. M.; Turlington, M.; Pu, L. Angew. Chem.,
Int. Ed. 2011, 50, 2368–2370. (f) Kaur, P.; Pindi, S.; Wever, W.; Rajale,
T.; Li, G. Chem. Commun. 2010, 46, 4330–4332. (g) Yukawa, T.; Seelig,
B.; Xu, Y.; Morimoto, H.; Matsunaga, S.; Berkessel, A.; Shibasaki, M.
J. Am. Chem. Soc. 2010, 132, 11988–11992. (h) Hatano, M.; Horibe, T.;
Ishihara, K. J. Am. Chem. Soc. 2010, 132, 56–57. (i) Liu, W.-J.; Lv, B.-D.;
Gong, L.-Z. Angew. Chem., Int. Ed. 2009, 48, 6503–6506. (j) Sone, T.; Lu,
G.; Matsunaga, S.; Shibasaki, M. Angew. Chem., Int. Ed. 2009, 48, 1677–1680.
(k) Muramatsu, Y.; Harada, T. Angew. Chem., Int. Ed. 2008, 47, 1088–1090.
Crystallography. Single crystals of 700, 9 THF, and 11 Et2O 0.25
3
3
3
THF were analyzed using a Bruker D8/APEX II CCD diffractometer,
with graphite-monochromated Mo Ka radiation at 173 K. Programs for
diffractometer operation, data collection, data reduction, and absorption
correction were those supplied by Bruker. Details of data collection,
solution, and refinement are given in Table 3. The structures were solved
using Patterson/structure expansion (DIRDIF-2008;33 for 700, 9) or
SHELXS-97 (11) and were refined using full-matrix least-squares on
F2 in SHELXL-97.34 For 9 THF, OꢀC distances within the disordered
3
THF solvate were constrained to be equal (within 0.03 Å) to a common
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(6) Selected examples or reviews of recent BINO complex-catalyzed
CdC bond elaborations. FriedelꢀCrafts alkylations: (a) Bandini, M.;
Umani-Ronchi, A. Catalytic Asymmetric Friedel-Crafts Alkylations; Wiley-
VCH: Weinheim, 2009. Olefin hydroaminoalkylation or hydroamina-
tion/cyclization: (b) Reznichenko, A. L.; Emge, T. J.; Audorsch, S.; Klauber,
E. G.; Hultzsch, K. C.; Schmidt, B. Organometallics 2011, 30, 921–924. (c)
Gribkov, D. V.; Hultzsch, K. C.; Hampel, F. J. Am. Chem. Soc. 2006,
128, 3748–3759. Cycloaddition:(d) Repka, L. M.; Ni, J.; Reisman, S. E.
J. Am. Chem. Soc. 2010, 132, 14418–14420. (e) Yan, P.; Jing, H. Adv. Synth.
Catal. 2009, 351, 1325–1332. (f) Ward, D. E.; Shen, J. Org. Lett. 2007,
9, 2843–2846. Olefin metathesis:(g) Sattely, E. S.; Meek, S. J.; Malcolmson,
S. J.; Schrock, R. R.; Hoveyda, A. H. J. Am. Chem. Soc. 2009, 131, 943–953.
(7) For PtꢀBINO complexes, see: (a) Peng, H.-Y.; Lam, C.-K.; Mak,
T. C. W.; Cai, Z.; Ma, W.-T.; Li, Y.-X.; Wong, H. N. C. J. Am. Chem. Soc.
2005, 127, 9603–9611. (b) Voshell, S. M.; Gagnꢀe, M. R. Organometallics
2005, 24, 6338–6350. (c) Ait-Haddou, H.; Leeder, S. M.; Gagnꢀe, M. R.
Inorg. Chim. Acta 2004, 357, 3854–3864. (d) Doherty, S.; Newman,
C. R.; Rath, R. K.; van den Berg, J.-A.; Hardacre, C.; Nieuwenhuyzen, M.;
Knight, J. G. Organometallics 2004, 23, 1055–1064. (e) Doherty, S.;
Newman, C. R.; Rath, R. K.; Luo, H.-K.; Nieuwenhuyzen, M.; Knight,
J. G. Org. Lett. 2003, 5, 3863–3866. (f) Becker, J. J.; Gagnꢀe, M. R.
Organometallics 2003, 22, 4984–4998. (g) Brunkan, N. M.; Gagnꢀe, M. R.
Organometallics 2002, 21, 4711–4717. (h) Becker, J. J.; White, P. S.;
Gagnꢀe, M. R. J. Am. Chem. Soc. 2001, 123, 9478–9479. (i) Tudor, M. D.;
Becker, J. J.; White, P. S.; Gagnꢀe, M. R. Organometallics 2000, 19,
4376–4384. (j) Brunkan, N. M.; White, P. S.; Gagnꢀe, M. R. J. Am. Chem.
Soc. 1998, 120, 11002–11003. (k) Brunkan, N. M.; White, P. S.; Gagnꢀe,
M. R. Angew. Chem., Int. Ed. 1998, 37, 1579–1582. For Pd derivatives,
see (c), (e), and:(l) Pelz, K. A.; White, P. S.; Gagnꢀe, M. R. Organome-
tallics 2004, 23, 3210–3217. (m) Bergens, S. H.; Leung, P. H.; Bosnich,
B.; Rheingold, A. L. Organometallics 1990, 9, 2406–2408.
J. Chem. Soc., Dalton Trans. 1977, 1546–1557. (b) Cole-Hamilton, D. J.;
Young, R. J.; Wilkinson, G. J. Chem. Soc., Dalton Trans. 1976, 1995–2001.
(c) Christ, M. L.; Sabo-Etienne, S.; Chung, G.; Chaudret, B. Inorg. Chem.
1994, 33, 5316–5319. (d) Snelgrove, J. L.; Conrad, J. C.; Yap, G. P. A.;
Fogg, D. E. Inorg. Chim. Acta 2003, 345, 268–278. (e) Abdur-Rashid, K.;
Fedorkiw, T.; Lough, A. J.; Morris, R. H. Organometallics 2004, 23, 86–94.
(16) Use of the less toxic K2(BINO) gave impure products and was
therefore not pursued.
(17) Eelman, M. D.; Blacquiere, J. M.; Moriarty, M. M.; Fogg, D. E.
Angew. Chem., Int. Ed. 2008, 47, 303–306. Angew. Chem. 2008, 120, 309–312.
(18) Monfette, S.; Duarte Silva, J. A.; Gorelsky, S. I.; Dalgarno, S. J.;
dos Santos, E. N.; Araujo, M. H.; Fogg, D. E. Can. J. Chem. 2009, 87,
361–367.
(19) We originally described the binding of the “aryloxy” ring in 5 as
η5-C5 (ref 14); such a structure was crystallographically established for
the related phenoxide complex RuH(η5-C6H5O)(PPh3)2, among others
(refs 15d,15e). Compilation of the 13C{1H} NMR chemical shift data
for this and other complexes in the present work revealed that the values
for 5 are in fact consistent with η6-coordination of the naphtholate ring.
(20) Cf. 1:1 70:700 at ꢀ80 °C in C7D8. Attempts to extract activation
parameters from a van’t Hoff analysis were hindered by emergence of a
further, unidentifiedprocess. The position ofthe70ꢀ700 equilibrium is also
strongly solvent-dependent; see the Supporting Information for details.
(21) Mann, B. E. J. Magn. Reson. 1976, 21, 17–23.
(22) (a) Wilkinson, G.;Gilbert, J. D. J. Chem. Soc. A 1969, 1749–1753.
(b) Wilkinson, G.; Cole-Hamilton, D. J. J. Chem. Soc., Dalton Trans.
1979, 1283–1289.
(23) Wakatsuki, Y.; Yamazaki, H.; Kumegawa, N.; Satoh, T.; Satoh,
J. Y. J. Am. Chem. Soc. 1991, 113, 9604–9610.
(24) Gutmann, V. Coord. Chem. Rev. 1976, 18, 225–255.
(25) The chemical shifts observed on cooling to ꢀ60 °C (C1, 125.6;
C2, 148.0; C10, 116.0; C20, 162.0 ppm; cf., ranges shown in Figure 3a)
are consistent with η3,η1-coordination of the BINO ligand in 13, with
the exception of the signal for C1. The latter is ca. 30 ppm downfield of
the average room-temperature value exhibited by other such complexes;
see Table 1. The difference may reflect reduced backbonding onto the
enolate moiety due to competition with the π-acidic vinylidene ligand;
see later.
(26) Pregosin and co-workers have convincingly demonstrated the
ubiquity of “supplemental stabilization”, via σ- or π-donation from
aromatic sites, of coordinatively unsaturated metal centers bearing
atropisomeric phosphine ligands such as BINAP, MOP, and MeO-
BIPHEP, as well as some phosphoramidites. See: (a) Pregosin, P. S.
Chem. Commun. 2008, 4875–4884. (b) Pregosin, P. S. Coord. Chem. Rev.
2008, 252, 2156–2170.
(8) A few group 9 BINO complexes have also been reported. See:
Paisner, S. N.; Lavoie, G. G.; Bergman, R. G. Inorg. Chim. Acta 2002,
334, 253–275 and ref 11, which describes Ir and Rh derivatives, as well as the
first Ru example.
(9) Selected reviews: (a) Delaude, L.; Demonceau, A. NHC-Iron,
Ruthenium and Osmium Complexes in Catalysis. In N-Heterocyclic Carbenes;
Diez-Gonzalez, S., Ed.; RSC: Oxford, 2011; Vol. 6, pp 196ꢀ227. (b)
Mezzetti, A. Dalton Trans. 2010, 39, 7851–7869. (c) Odedra, A.; Liu, R.-S.
Ruthenium Vinylidenes in the Catalysis of Carbocyclization. In Metal
Vinylidenes and Allenylidenes in Catalysis; Bruneau, C., Dixneuf, P. H., Eds.;
Wiley-VCH: Weinheim, 2008; pp 193ꢀ216. (d) Morris, R. H. Ruthenium
and Osmium. In Handbook of Homogeneous Hydrogenation; de Vries, J. G.,
Elsevier, C. J., Eds.; Wiley-VCH: Weinheim, 2007; Vol. 1, pp 45ꢀ70. (e)
Faller, J.; Parr, J. Curr. Org. Chem. 2006, 10, 151–163. (f) Bruneau, C.; Derien,
S.; Dixneuf, P. H. Top. Organomet. Chem. 2006, 19, 295–326. (g) Trost, B. M.;
Frederiksen, M. U.; Rudd, M. T. Angew. Chem., Int. Ed. 2005, 44, 6630–6666.
(h) Naota, T.; Takaya, H.; Murahashi, S.-I. Chem. Rev. 1998, 98, 2599–2660.
(10) Selected recent reviews of Ru-catalyzed olefin metathesis:
(a) Vougioukalakis, G. C.; Grubbs, R. H. Chem. Rev. 2010, 110, 1746–
1787. (b) Lozano-Vila, A. M.; Monsaert, S.; Bajek, A.; Verpoort, F. Chem.
Rev. 2010, 110, 4865–4909. (c) Monfette, S.; Fogg, D. E. Chem. Rev. 2009,
109, 3783–3816. (d) Samojlowicz, C.; Bieniek, M.; Grela, K. Chem. Rev.
2009, 109, 3708–3742. (e) Malacea, R.; Dixneuf, P. H. Ruthenium
Allenylidenes and Indenylidenes as Catalysts in Alkene Metathesis. In
Metal Vinylidenes andAllenylidenesinCatalysis; Bruneau, C., Dixneuf, P. H.,
Eds.; Wiley-VCH: Weinheim, 2008; pp 251ꢀ277.
(27) The prime label on these carbon nuclei differentiates the two
naphthol rings within unsymmetrical complexes: in η1,η1-bound com-
plexes such as 3a/3b, it is arbitrary, but in variable-hapticity BINO
complexes, specifically, it designates the ring of lower hapticity.
(28) Bruce, M. I. Chem. Rev. 1998, 98, 2797–2858.
(29) We note that the solid-state structure of 700 reveals π-stacking
interactions between the BINO and the PPh3 phenyl rings, as well as
between the phenyl rings themselves: if these interactions are retained in
solution, the resulting ring currents could affect the locations of the
aromatic signals (see: Rathore, R.; Abdelwahed, S. H.; Guzei, I. A. J. Am.
Chem. Soc. 2003, 125, 8712–8713), limiting the diagnostic value of the
1
BINO chemical shifts. H and 13C NMR resonances for the phenyl
nuclei in 700 appear within their usual chemical shift ranges, however,
suggesting that π-stacking is lost in solution, or has minimal influence.
While further examples of the unique η3,η3-BINO coordination mode
will clarify the issue, we are thus inclined to view the NMR shifts for the
BINO ligand in 700 as arising from the metalꢀligand interaction, with a
corresponding diagnostic value.
(11) Panichakul, D.; Su, Y.; Li, Y.; Deng, W.; Zhao, J.; Li, X. Organome-
tallics 2008, 27, 6390–6392.
(12) Blacquiere, J. M.; McDonald, R.; Fogg, D. E. Angew. Chem., Int.
Ed. 2010, 49, 3807–3810.
(13) Seddon, E. A.; Seddon, K. R. The Chemistry of Ruthenium; Elsevier:
Amsterdam, 1984.
(14) Snelgrove, J. L.; Conrad, J. C.; Moriarty, M. M.; Yap, G. P. A.;
Fogg, D. E. Organometallics 2005, 24, 103–109.
(30) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth.
1970, 12, 237–40.
(31) Galvan-Arzate, S.; Santamaria, A. Toxicol. Lett. 1998, 99, 1–13.
(32) The majority of BINO signals can be located for complexes 70,
700, 9, 10, 11, 12, and 13. Full assignment of all 13C{1H} NMR peaks is
(15) Related η6- and η5-ArO structures form on treating 6a, 6b, and
other labile Ru precursors with aryloxide salts. See, for example:
(a) Chaudret, B. N.; Cole-Hamilton, D. J.; Nohr, R. S.; Wilkinson, G.
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complicated by the large number of aromatic signals (these account for
all resonances, with the exception of the singlets for MeCN in 9 and 10,
and the vinylidene group in 13), and the simultaneous presence of two
1
species in solution for 70/700, 9/10, and 11/12. Unassigned H NMR
signals for BINO, py, and/or PPh3 protons are designated as Ar or Ph.
(33) Beurskens, P. T.; Beurskens, G.; de Gelder, R.; Smits, J. M. M.;
Garcia-Granda, S.; Gould, R. O. The DIRDIF-2008 Program System; Crystal-
lography Laboratory, Radboud University: Nijmegen, The Netherlands,
2008.
(34) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.
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