Trapping of an NiII Sulfide by a CoI Fulvene Complex

Article abstract of DOI:10.1021/acs.organomet.7b00123

The reaction of [L^tBuNi^II(SCPh₃)] (L^tBu = {(2,6-ⁱPr₂C₆H₃)NC(^tBu)}₂CH) with Cp*₂Co yields a Ni^I cobaltocenium thiolate complex, [L^tBuNi^I(SCH₂Me₄C₅)Co(Cp*)] (1), along with HCPh₃. Formation of this complex is proposed to occur via the reaction of a transient Ni^II sulfide, [Cp*₂Co][L^tBuNi^II(S)], with a Co^I fulvene complex, [CoCp*(C₅Me₄CH₂)]. The latter complex is formed in situ by reaction of [Cp*₂Co]⁺ with [CPh₃]^?. Control experiments, as well as cyclic voltammetry measurements of 1, are used to support the proposed mechanism.

Full text of DOI:10.1021/acs.organomet.7b00123

Article
pubs.acs.org/Organometallics
II
I
Trapping of an Ni Sulfide by a Co Fulvene Complex
Nathaniel J. Hartmann, Guang Wu, and Trevor W. Hayton*
Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
S Supporting Information
*
ABSTRACT: The reaction of [LtBuNi (SCPh )] (L
II
tBu
= {(2,6- Pr C H )NC( Bu)} CH) with Cp* Co yields a Ni
2 6 3 2 2
i
t
I
3
tBu
I
cobaltocenium thiolate complex, [L Ni (SCH Me C )Co(Cp*)] (1), along with HCPh . Formation of this complex is
2
4
5
3
II
tBu II
I
proposed to occur via the reaction of a transient Ni sulfide, [Cp* Co][L Ni (S)], with a Co fulvene complex,
2
+
−
[
CoCp*(C Me CH )]. The latter complex is formed in situ by reaction of [Cp* Co] with [CPh ] . Control experiments, as
5
4
2
2
3
well as cyclic voltammetry measurements of 1, are used to support the proposed mechanism.
INTRODUCTION
deprotection” reaction with a reducing agent that generates a
■
noncoordinating cation and, in particular, we identified Cp* Co
2
The synthesis of late-transition-metal (groups 9−11) terminal
chalcogenides (especially oxygen and sulfur) has long been a
target of synthetic inorganic chemists. This class of
compounds tends to be highly reactive,
as an ideal choice for this application.
1
Herein, we report the reductive deprotection of
tBu II
2
−4
[L Ni (SCPh )] with Cp* Co, which unexpectedly leads to
3
2
and as a result,
I
the generation of the Ni cobaltocenium thiolate complex
only a few well-characterized late-metal terminal chalcogenides
tBu
I
V
[L Ni (SCH
reaction of a putative nickel sulfide, [Cp* Co][(L )Ni (S)],
2
Me C )Co(Cp*)], which likely forms via the
2 4 5
tBu II
are known, including [Ir (O)(Mes) ] (Mes = 2,4,6-Me C H )
3
3
6
2
IV
and [Pt (O)(PCN)][BF ] (PCN = C H [CH P(tBu) ]-
4
6
3
2
2
5
,6
with deprotonated decamethylcobaltocenium, [CoCp*-
(
(
(
CH CH NMe )). A number of late-transition-metal carbene
2 2 2
2
−
2−
3−
(C
5
Me CH )].
4 2
CR ), nitrene (NR ), nitride (N ), and phosphinidene
PR ) complexes have also been reported in recent years.
2
2−
7−18
RESULTS AND DISCUSSION
■
While a few of these complexes have been isolated, they tend to
be extremely reactive and often can only be observed
Addition of 2 equiv of Cp* Co to a stirred, deep blue solution
2
tBu II
1
9−22
of [L Ni (SCPh )] in cold (−25 °C) THF results in a rapid
color change to deep red-brown (eq 1). The reaction mixture
spectroscopically.
Nonetheless, it is clear that synthetic
3
chemists are now beginning to identify the combination of
ligand requirements and synthetic procedures that can
successfully generate late-metal−ligand multiple bonds.
II
We recently reported the synthesis of an Ni sulfide, [K(18-
R
II
R
i
crown-6)][L Ni (S)] (L = {(2,6- Pr C H )NC(R)} CH, R =
2
6
3
2
t
23
II
Bu, Me), by 2e reduction of the Ni triphenylmethanethio-
R
II
late complex [L Ni (SCPh )]. This reaction results in selective
3
−
cleavage of the S−C bond and release of [CPh ] , a strategy
that we have coined “reductive deprotection”. In both the solid
state and solution, the K ion of the [K(18-crown-6)] moiety
3
+
+
R
II
−
is coordinated to the sulfide ligand of [L Ni (S)] . However,
despite the presence of the coordinating [K(18-crown-6)]+
was stirred for 3 h, and following workup,
tBu
I
[
L Ni (SCH Me C )Co(Cp*)] (1) was successfully isolated
2 4 5
cation, our preliminary reactivity studies have demonstrated
that the sulfide ligand in [L Ni (S)] is highly nucleophilic and
R
II
−
as dark brown plates in 69% yield. Interestingly, reaction of
tBu
II
[
L
Ni (SCPh )] with Cp Co results in no reaction,
3 2
can react with a variety of electrophiles, including N O, CS ,
2
2
2
3−25
demonstrating that this reagent is not sufficiently reducing to
initiate the required C−S bond cleavage.
CO, and NO,
resulting in our classification of this complex
as a “masked” terminal sulfide. Importantly, however, the
presence of the coordinating [K(18-crown-6)] cation likely
+
tempers the reactivity of the sulfide ligand in this complex.
Consequently, we have sought to perform the “reductive
Received: February 17, 2017
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.7b00123
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Organometallics
Article
tBu II
Complex 1 crystallizes in the monoclinic space group P2 /c,
and its solid-state molecular structure is shown in Figure 1. It
[L Ni (SCPh )] in THF-d in an NMR tube results in a rapid
3 8
1
1
color change from deep blue to dark red-brown. A H NMR
spectrum of the reaction mixture, taken 5 min after the addition
of Cp* Co, reveals the complete consumption of both
2
tBu II
[
L Ni (SCPh )] and Cp* Co, concomitant with the for-
3 2
II
mation of a new Ni complex (Figures S1−S3 in the
Supporting Information). We have tentatively identified this
complex as the Ni sulfide [Cp* Co][L Ni (S)] (2). Our
assignment was made on the basis of the similarity of its H
NMR resonances with those of the previously characterized Ni
sulfide [K(18-crown-6)][L Ni (S)]. For example, complex
II
tBu II
2
1
II
tBu II
23
2
features resonances at −101.97, −1.37, and 15.93 ppm, which
tBu t
are assignable to the γ-proton of the L ligand, its Bu
substituents, and one environment of its diastereotopic Pr
i
methyl groups, respectively. For comparison, these resonances
appear at −115.21, −0.88, and 16.25 ppm, respectively, for the
II
tBu II
23
original Ni sulfide, [K(18-crown-6)][L Ni (S)]. Also
present in the 5 min spectrum are resonances assignable to
I
the Co fulvene complex [CoCp*(C Me CH )] (3) (Figures
5
4
2
32
33
S1−S3), as well as resonances assignable to HCPh3.
After 30 min, the resonances assignable to complexes 2 and 3
decrease in intensity, while those assignable to complex 1 begin
to appear. After 3 h, only trace amounts of complex 2 can be
1
detected in the H NMR spectrum of the reaction mixture,
while those assignable to 1 have grown in intensity. Curiously,
we also observe a broad resonance at 21.0 ppm in the 3 h
spectrum, which we have assigned to Cp* Co. These spectra
2
Figure 1. ORTEP drawing of [LtBuNi (SCH Me C )Co(Cp*)]·
I
also feature a broad singlet at about −1.6 ppm, which we have
2
4
5
t
I
C H O (1·C H O) shown with 50% thermal ellipsoids. Hydrogen
atoms and a C H O solvate molecule have been omitted for clarity.
assigned to the Bu groups of an as yet unidentified Ni β-
diketiminate complex. This assignment was made on the basis
of its chemical shift along with the broadness of the resonance.
This complex is present in an approximately 2:5 ratio, relative
to complex 1 (Figure S8 in the Supporting Information).
Unfortunately, our efforts to isolate and structurally character-
ize this material have been unsuccessful; however, given the
4
10
4
10
4
10
Selected bond distances (Å) and angles (deg): Ni1−N1 1.910(4),
Ni1−N2 1.902(5), Ni1−S1 2.181(2), S1−C1 1.870(7), C1−C37
1
1
.498(8); N1−Ni1−N2 98.2(2), N1−Ni1−S1 130.5(2), N2−Ni1−S1
31.2(1), Ni1−S1−C1 107.2(2).
I
features a three-coordinate Ni center ligated by a cobaltoce-
nium thiolate moiety. The Ni−S and C−S bond lengths of
.181(2) and 1.870(7) Å, respectively, are both consistent with
1
similarity of its H NMR spectrum to that of 1, we conclude
tBu
I
−
that it is similar in structure: e.g., [(L )Ni (X)] .
2
23,26
To rationalize our observations, we hypothesize that
single bonds.
For comparison, the Ni−S bond length in the
23
tBu II
reduction of [L Ni (SCPh )] with 2 equiv of Cp* Co results
3
2
starting material is markedly shorter (2.0869(1) Å). The Ni−
III
in formation of 2 and 1 equiv of [Cp* Co ][CPh ] (Scheme
2
3
N bond lengths in 1 (1.901(4) and 1.902(5) Å) are also longer
+
−
II
1). Deprotonation of [Cp* Co] by [CPh ] subsequently
2 3
32
than those found in the Ni starting material (1.863(3) and
.862(3) Å), consistent with the larger ionic radius anticipated
for Ni vs Ni . Moreover, the Ni−N bond lengths in 1 are
consistent with those of other L Ni complexes.
generates [CoCp*(C Me CH )] (3) and HCPh . Finally,
5
4
2
3
1
I
II
coupling of the nucleophilic terminal sulfide ligand in 2 with
the methylene carbon of 3 results in the formation of complex
tBu
I
26,27
Finally,
the average distance from the Co atom to the ring carbon
Scheme 1
atoms of the Cp* ligand is 2.033 Å, which is characteristic of
III
28,29
Cp*Co1 complexes.
The H NMR spectrum of 1 in C D is typical of those
6
6
I
26,27,30
reported for other Ni β-diketiminate complexes.
It
features a very broad resonance at −0.8 ppm, which is
t
assignable to the Bu groups on the backbone of the β-
diketiminate ligand. Additionally, a broad singlet at 0.7 ppm is
assignable to the methyl groups of the Cp* ligand attached to
III
Co , while resonances at 0.3 and 3.9 ppm are assignable to the
two unique methyl environments of the SCH Me C ring.
2
4 5
Complex 1 exhibits an effective magnetic moment of 1.67 μ , as
B
31
determined by the Evans method. This value is consistent
with that anticipated for a Ni complex with an S = 1/2 ground
I
2
6,27
state.
In an effort to better understand the formation of 1, we
tBu II
monitored the reaction of [L Ni (SCPh )] with Cp* Co by
3
2
1
H NMR spectroscopy. Addition of 2 equiv of Cp* Co to
2
B
DOI: 10.1021/acs.organomet.7b00123
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
+
1
, concomitant with reduction of the [Cp* Co] counterion.
2
The latter observation is somewhat surprising, given the high
+
reduction potential of [Cp* Co] (1.94 V vs Fc/Fc in
2
3
4
CH Cl ). Formally, the C−S bond forming reaction results
2
2
I
in a 2e oxidation of the Co center in 3. One of the electrons is
tBu
II
−
transferred to the Ni center in [(L )Ni (S)] , while the other
III +
II
is transferred to [Cp* Co ] , re-forming Cp* Co .
2
2
For comparison, there are several other examples of C−S
35−40
bond formation mediated by nucleophilic metal sulfides.
−
For example, [ReS4] reacts with norbornene to form the
dithiolate complex [ReS (S C H )] . Similarly, [Mo (μ -S)(μ-
S) (H O) ] reacts with alkynes to generate a dithiolene
ligand by formation of two new C−S bonds. Also of note,
CpMo(μ-S)] (S CH ) has been reported to catalyze the
−
2
2
7
10
3
3
4+
3
2
9
41
[
2
2
2
42
hydrogenation of acetylene, via a dithiolene intermediate. Our
proposed reaction pathway is also consistent with the known
chemical reactivity of [Cp*Co(C Me CH )] (3). For example,
Figure 2. Cyclic voltammogram of complex 1 (200 mV/s, vs Fc/Fc+),
measured in THF with 0.1 M [NBu ][PF ] as the supporting
5
4
2
4
6
reaction of [Cp*Co(C Me CH )] (3) with 1-mesityl-2,3,4,5-
electrolyte. The asterisk indicates a feature tentatively assigned to
5
4
2
Cp* Co, which is present as a minor impurity.
tetraphenylborole (MesBC Ph ) results in rapid C−B bond
2
4
4
formation and generation of a zwitterionic cobaltocenium
32
borate, [Cp*Co(C Me CH B(Mes){C Ph }]. Similarly, re-
5
4
2
4
4
action of an [Fe S ] cluster with [Cp*Co(C Me CH )] has
reaction, demonstrating that common olefins, alone, will not
8
7
5
4
2
2
8
tBu II
−
been shown to result in Fe−C bond formation.
couple with the sulfide ligand in [L Ni (S)] . Likewise,
tBu
To test our mechanistic hypothesis, we monitored the
reaction of [K(18-crown-6)][L Ni(S)] with 3 also results in
reaction of independently prepared [Cp* Co][PF ] with
no reaction. Thus, it appears that the C−S bond forming step
2
6
[
K(18-crown-6)][CPh ]. Upon mixing in pyridine, we observe
likely requires the presence of both a redox-active counter-
3
+
rapid formation of 3 and HCPh (eq 2) (Figure S7 in the
cation (i.e., [Cp*
2
Co] ) and a formally redox active olefin (i.e.,
3
Supporting Information). Given this result, in addition to the
[Cp*Co(C Me CH
5
4
2
)]) to proceed.
1
appearance of 3 in the in situ H NMR experiment, we believe
CONCLUSIONS
In summary, we have shown that reduction of the nickel
triphenylmethythiolate complex [L Ni (SCPh )] with
that the proposed intermediacy of [Cp*Co(C Me CH )] (3)
5
4
2
■
in the formation of 1 is reasonable.
tBu
II
3
III
II
[
Cp* Co ][PF ] + [K(18‐c‐6)][CPh ]
Cp* Co generates a transient Ni sulfide complex, [Cp* Co]-
2
6
3
2
2
tBu II
+
Py‐d
[L Ni (S)]. A subsequent deprotonation of [Cp* Co] by
2
I
5
I
⎯
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯→ [Cp*Co (C Me CH )] + HCPh
−
5
4
2
3
[CPh ] gives the Co fulvenyl complex [Cp*Co(C Me CH )],
−
18‐c‐6,−KPF6
3
5
4
2
3
(2)
tBu II
which couples with the sulfide ligand in [Cp* Co][L Ni (S)]
2
I
tBu II
to form a Ni cobaltocenium thiolate complex,
We also monitored the reaction of [L Ni (SCPh )] with
3
tBu
I
1
[
L Ni (SCH Me C )Co(Cp*)], concomitant with the reduc-
Cp* Co by H NMR spectroscopy in the presence of an
2 4 5
2
tion of the cobaltocenium cation. This result expands the scope
of late-metal sulfide reactivity and demonstrates that “reductive
deprotection” is possible with a variety of reducing agents, not
internal standard. Under these conditions, the yield of HCPh3
was determined to be 88% (Figure S6 in the Supporting
Information), which is also consistent with the proposed
mechanism.
23,43,44
just KC8 as previously demonstrated,
suggesting a
broader scope of this transformation than hitherto recognized.
The solution-phase redox properties of 1 were investigated
by cyclic voltammetry. In THF at room temperature, the cyclic
voltammogram of 1 displays one quasi-reversible redox feature
and one reversible redox feature, at −2.20 and −1.38 V (vs Fc/
EXPERIMENTAL SECTION
General Considerations. All reactions and subsequent manipu-
lations were performed under anaerobic and anhydrous conditions
under an atmosphere of nitrogen. Hexanes, tetrahydrofuran, diethyl
■
+
Fc ), respectively (Figure 2). The feature at −2.20 V is
II
III
tentatively attributed to the Co /Co redox couple, while the
II
I
ether (Et
DRI-SOLV solvent purification system and stored over 3 Å sieves for
4 h prior to use. Benzene-d , THF-d , pyridine-d , and pentane were
2
O), and toluene were dried using a Vacuum Atmospheres
feature at −1.38 V is tentatively attributed to the Ni /Ni redox
II
III
couple. The Co /Co couple was assigned to be quasi-
2
6
8
5
reversible on the basis of the large i /ip,c ratios observed at
p,a
dried over 3 Å molecular sieves for 24 h prior to use.
high scan rates (Table S2 in the Supporting Information). In
Decamethylcobaltocene (Cp* Co) was purified by recrystallization
2
II
I
tBu II
tBu
support of our assignments, we note that our Ni /Ni redox
from hexanes at −25 °C. [L Ni (SCPh )], [K(18-crown-6)][L Ni-
3
potential agrees well with those previously reported for
(S)], [Cp*
Co][PF ], (CH C Me )Co(Cp*), and [K(18-crown-
2 6 2 5 4
tBu II
6
)][CPh ] were synthesized according to the previously reported
[
L Ni (SR)] (R = Et, −1.40 V; R = Ph, −1.60 V; vs Fc/
3
2
3,32,43,45
+
26
III
II
procedures.
All other reagents were purchased from
Fc ). In addition, the Co /Co couple in 1 is more negative
0
/+
+
commercial suppliers and used as received.
than that reported for [Cp* Co] (−1.94 V vs Fc/Fc in
2
1
19
31
3
4
−
H and F NMR spectra, and Evans method determinations, were
CH Cl ), demonstrating that [1] , in fact, can reduce
2
2
recorded on a Agilent Technologies 400-MR DD2 400 MHz
+
[
Cp* Co] as proposed in Scheme 1.
2
spectrometer or a Varian UNITY INOVA 500 MHz spectrometer.
Finally, to explore the generality of this transformation, we
1
19
H and F NMR spectra were referenced to external SiMe using the
4
tBu
monitored the reaction of [K(18-crown-6)][L Ni(S)] with a
residual protio solvent peaks as internal standards. IR spectra were
recorded on a Nicolet 6700 FT-IR spectrometer. Electronic absorption
spectra were recorded on a Shimadzu UV3600 UV−NIR spectrom-
variety of olefins, including cyclohexene, norbornene, and
1
styrene, by H NMR spectroscopy. In each case, we observe no
C
DOI: 10.1021/acs.organomet.7b00123
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
eter. Elemental analyses were performed by the Micro-Mass Facility at
the University of California, Berkeley, CA.
at −25 °C for 72 h resulted in the deposition of dark brown plates of
tBu
I
[L Ni (SCH Me C )Co(Cp*)], which were isolated by decanting off
2
4 5
1
Cyclic Voltammetry Measurements. CV experiments were
performed with a CH Instruments 600c potentiostat, and the data
were processed using CHI software (version 6.29). All experiments
were performed in a glovebox using a 20 mL glass vial as the cell. The
working electrode consisted of a platinum disk embedded in glass (2
mm diameter), the counter electrode and the reference electrode were
platinum wires. Solutions employed for CV studies were typically 1
mM in analyte and 0.1 M in [NBu ][PF ]. All potentials are reported
the supernatant (22 mg, 67% yield). H NMR (400 MHz, 25 °C,
THF-d ): 5 min, δ 25.75 (s, 2), 25.24 (s, 2), 19.6 (br s, I), 15.93 (s, 2),
8
12.5 (br s, I), 7.3−7.05 (15 H, HCPh , Ar-H), 6.13 (s, 2), 5.57 (s, 1H,
3
HCPh ), 2.59 (br s, 2H, 3, CH ), 1.78 (br s, 6H, 3, CH ), 1.49 (br s,
3
2
3
15H, 3, Cp* CH ), 1.03 (br s, 6H, 3, CH ), 0.2 (br s, I), −1.37 (s, 2),
3
3
−1.6 (br s, I), −11.3 (br s, I), −15.93 (s, 2), −101.97 (s, 2); 30 min, δ
25.71 (s, 2), 25.23 (s, 2), 19.6 (overlapping br s, 1 and I), 15.92 (s, 2),
12.5 (overlapping br s, 1 and I), 7.6 (br s, Cp* Co), 7.3−7.05 (15 H,
4
6
2
0/+
versus the [Cp Fe] couple.
HCPh , Ar-H), 6.13 (s, 2), 5.57 (s, 1H, HCPh ), 2.6 (br s, 2H, 3,
2
3
3
tBu II
Preparative-Scale Reaction of [L Ni (SCPh )] with Cp* Co
CH ), 1.8 (br s, 6H, 3, CH ), 1.5 (br s, 15H, 3, Cp* CH ), 1.4 (br s,
2 3 3
3
2
tBu
I
To Yield [L Ni (SCH Me C )Co(Cp*)] (1). To a deep blue, cold
1), 1.0 (br s, 6H, 3, CH ), 0.2 (br s, I), −1.3 (br s, 1), −1.35 (s, 2),
2
4
5
3
tBu II
(
−25 °C), stirred solution of [L Ni (SCPh )] (50.0 mg, 0.0598
−1.6 (br s, I), −11.4 (overlapping br s, 1 and I), −15.90 (s, 2),
−101.80 (s, 2); 1.5 h, δ 25.76 (s, 2), 25.26 (s, 2), 19.7 (overlapping br
s, 1 and I), 15.93 (s, 2), 13.7 (br s, Cp* Co), 7.3−7.05 (15 H, HCPh ,
3
mmol) in THF (2 mL) was added Cp* Co (39.4 mg, 0.1196 mmol) in
2
cold (−25 °C) THF (1 mL). This resulted in immediate formation of
a dark red-brown solution. This mixture was warmed to room
temperature with stirring. During this time the solution transformed to
dark brown. This solution was stirred for 3 h, whereupon the reaction
mixture was filtered through a Celite column supported on glass wool
2
3
Ar-H), 6.14 (s, 2), 5.57 (s, 1H, HCPh ), 3.5 (br s, 1), 2.6 (br s, 2H, 3,
3
CH ), 1.8 (br s, 6H, 3, CH ), 1.5 (br s, 15H, 3, Cp* CH ), 1.4 (br s,
2
3
3
1), 1.0 (br s, 6H, 3, CH ), 0.2 (br s, I), −1.3 (br s, 1), −1.35 (s, 2),
3
−1.6 (br s, I), −11.3 (overlapping br s, 1 and I), −15.92 (s, 2),
(
0.5 cm × 2 cm), which afforded a small plug of black solid and a
−101.96 (s, 2); 3 h, δ 25.71 (s, 2), 21.0 (br s, Cp* Co), 20.0
2
brown-red filtrate. The volatiles were removed from the filtrate in
vacuo to produce a dark brown residue. This residue was washed with
hexanes (1 mL × 2), extracted into toluene (1 mL), filtered through a
Celite column supported on glass wool (0.5 cm × 2 cm), concentrated
to ca. 0.5 mL, and layered with pentane (1 mL). Storage of this
solution at −25 °C for 48 h resulted in the deposition of dark brown
(overlapping br s, 1 and I), 15.93 (s, 2), 12.6 (overlapping br s, 1 and
I), 7.3−7.05 (15 H, HCPh , Ar-H), 6.14 (s, 2), 5.57 (s, 1H, HCPh ),
3
3
3.5 (br s, 1), 2.6 (br s, 2H, 3, CH ), 1.8 (br s, 6H, 3, CH ), 1.5 (br s,
2
3
15H, 3, Cp* CH ), 1.4 (br s, 1), 1.0 (br s, 6H, 3, CH ), 0.2 (br s, I),
3
3
−1.3 (br s, 1), −1.30 (s, 2), −1.6 (br s, I), −11.6 (overlapping br s, 1
and I) ppm.
tBu
I
NMR-Scale Reaction of [LtBuNi (SCPh )] with Cp* Co in THF-
II
needles of [L Ni (SCH Me C )Co(Cp*)] (1), which were isolated
2
4
5
3
2
by decanting off the supernatant (17 mg). The supernatant was
concentrated in vacuo to 0.25 mL and layered with pentane (2 mL).
Further storage of this solution at −25 °C for 48 h led to the
deposition of more crystals (21 mg), which were isolated by decanting
off the supernatant (combined yield: 38 mg, 69%). Anal. Calcd for
C H CoN NiS: C, 71.73; H, 8.97; N, 3.04. Found: C, 71.90; H, 8.80;
d To Quantify the Yield of HCPh . To an NMR tube containing
8 3
tBu II
[L Ni (SCPh
(HMDSO) (2.5 μL, 0.012 mmol) in THF-d
Cp* Co (7.8 mg, 0.024 mmol) in THF-d (0.3 mL). After addition,
the solution quickly changed from blue to red-brown. An H NMR
spectrum taken after 4 h revealed the presence of 1, 3, HCPh , an
Co. The yield of
was determined to be 88% by integration of the methine
proton resonance of HCPh against the HMDSO internal standard.
H NMR (400 MHz, 25 °C, THF-d ): δ 19.9 (overlapping br s, 1 and
)] (10 mg, 0.012 mmol) and hexamethyldisiloxane
3
(0.3 mL) was added
8
2
8
1
5
5
82
2
3
1
I
N, 2.73. H NMR (400 MHz, 25 °C, C D ): δ 20.4 (br s), 13.0 (br s),
unidentified Ni -containing product (I), and Cp*
HCPh
2
6
6
3
.9 (br s, 6H, CH C Me , CH ), 0.7 (br s, 15 H, Cp*), 0.3 (br s, 6H,
3
2
5
4
3
CH C Me , CH ), −0.8 (br s, 18 H, C(CH ) ), −12.0 (br s). Of the
3
2
5
4
3
3 3
1
1
1 unique proton enviornments expected for 1, only seven resonances
8
1
are observed in the H NMR spectrum. We suggest that the
unobserved resonances are either too broad to be obsevered or are
overlapping with other peaks. Evans method (C D , 400 MHz, 25 °C,
I), 17.6 (Cp* Co), 12.5 (overlapping br s, 1 and I), 7.25−7.09 (15 H,
2
HCPh , Ar-H), 5.57 (s, 1H, HCPh ), 3.5 (br s, 1), 2.6 (br s, 2H, 3,
3
3
CH ), 1.8 (br s, 6H, 3, CH ), 1.5 (br s, 15H, 3, Cp* CH ), 1.4 (br s,
6
6
2
3
3
−1
0
.0054 M): 1.67 μ . IR (KBr pellet, cm ): 1624 (w), 1510 (m), 1477
1), 1.1 (br s, 6H, 3, CH ), 0.1 (br s, I), 0.07 (s, 18H, HMDSO), −1.3
B
3
(
m), 1446 (s), 1414 (s), 1385 (s), 1363 (s), 1319 (s), 1254 (w), 1219
(br s, 1), −1.5 (br s, I), −11.7 (overlapping br s, 1 and I) ppm.
(
w), 1192 (w), 1182 (w), 1155 (m), 1095 (m), 1059 (w), 1024 (m),
Reaction of [Cp* Co][PF ] and [K(18-crown-6)][CPh ] To
2
6
3
9
37 (w), 920 (w), 897 (w), 852 (w), 802 (w), 781 (m), 762 (m), 729
Yield (CH
containing [Cp*
(0.3 mL) was added [K(18-crown-6)][CPh
in pyridine-d (0.3 mL). Upon mixing, the deep red of [K(18-crown-
6)][CPh ] rapidly disappeared and the solution became pale brown-
2
Me
4
C
5
)Co(Cp*) (3) and HCPh
3
. To an NMR tube
(
4
m), 700 (s), 665 (w), 638 (m), 619 (w), 590 (w), 467 (m), 447 (m),
2
Co][PF
6
] (10.0 mg, 0.0183 mmol) in pyridine-d
] (8.7 mg, 0.0183 mmol)
5
−1
07 (w). UV−vis (C H , 1.0 mM, 25 °C): 443 nm (ε = 5770 L mol
3
6
6
−1
−1
−1
cm ), 527 nm (ε = 1020 L mol cm ).
5
tBu II
NMR-Scale Reaction of [L Ni (SCPh )] with Cp* Co in THF-
3
3
2
tBu II
1
d . To a J. Young NMR tube containing [L Ni (SCPh )] (30 mg,
green. An H NMR spectrum of the reaction mixture revealed the
8
3
0
0
.0359 mmol) in THF-d (0.5 mL) was added Cp* Co (23.6 mg,
formation of both (CH Me C )Co(Cp*) (3) and HCPh , on the basis
8
2
2
4
5
3
.0718 mmol). After addition, the color of the solution quickly
of a comparison of the observed resonances with the reported
1
32,33
1
changed from blue to red-brown. An in situ H NMR spectrum taken
literature spectra for 3 and HCPh3.
H NMR (400 MHz, 25 °C,
shortly after addition of Cp* Co revealed the presence of [Cp* Co]-
pyridine-d ): δ 7.15−7.05 (s, 15 H, HCPh , Ar-H), 5.51 (s, 1H,
2
2
5
3
tBu
II
I
[
(L )Ni (S)] (2), HCPh , an unidentified Ni -containing product
HCPh ), 3.27 (s, 24H, 18-crown-6), 1.46 (br s, 6H, 3, CH C Me ,
3
3
2
5
4
1
(
I), and (CH Me C )Co(Cp*) (3). An in situ H NMR spectrum
CH ), 1.34 (br s, 6H, 3, CH C Me , CH ), 1.28 (br s, 15H, 3, Cp*),
3 2 5 4 3
19
2
4
5
taken after 3 h revealed the disappearance of peaks assignable to 2, a
decrease in the intensity of the resonances assignable to 3, and the
0.90 (br s, 2H, 3, CH ) ppm. F NMR (376 MHz, 25 °C, pyridine-
2
1
−
d ): δ −72.97 (d, J , = 706 Hz, PF ) ppm.
5
FP
6
appearance of new resonances assignable to 1 and free Cp* Co. The
2
NMR tube was then bought into a glovebox and the solution was
transferred to a 20 mL scintillation vial. The volatiles were removed in
vacuo. The resulting brown residue was rinsed with hexanes (1 mL ×
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.7b00123.
■
*
S
2
), the rinsings were collected, and the volatiles were removed in
1
vacuo to give a brown solid. A H NMR spectrum of this material,
taken in C D , revealed the presence of HCPh , as indicated by the
6
6
3
3
3
appearance of the methine proton resonance at 5.50 ppm, and
Cp* Co, as indicated by a broad resonance at 46.7 ppm. The hexanes-
2
Experimental procedures, crystallographic details, and
insoluble solid was then extracted into THF (1 mL), filtered through a
Celite column supported on glass wool (0.5 cm × 2 cm), concentrated
spectral data for complex 1 (PDF)
Crystallographic data for complex 1 (CIF)
to ca. 0.25 mL, and layered with Et O (2 mL). Storage of this solution
2
D
DOI: 10.1021/acs.organomet.7b00123
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(
25) Hartmann, N. J.; Wu, G.; Hayton, T. W. J. Am. Chem. Soc. 2016,
AUTHOR INFORMATION
■
1
(
5
(
38, 12352−5.
26) Horn, B.; Limberg, C.; Herwig, C.; Braun, B. Inorg. Chem. 2014,
3, 6867−74.
27) Holland, P. L.; Cundari, T. R.; Perez, L. L.; Eckert, N. A.;
Lachicotte, R. J. J. Am. Chem. Soc. 2002, 124, 14416−24.
28) Ohki, Y.; Murata, A.; Imada, M.; Tatsumi, K. Inorg. Chem. 2009,
8, 4271−3.
(29) Heise, H.; Ko
Soc. 2002, 124, 10823−32.
30) Kothe, C.; Braun, B.; Herwig, C.; Limberg, C. Eur. J. Inorg.
Corresponding Author
E-mail for T.W.H.: hayton@chem.ucsb.edu.
*
ORCID
Trevor W. Hayton: 0000-0003-4370-1424
Notes
The authors declare no competing financial interest.
(
4
̈
hler, F. H.; Herker, M.; Hiller, W. J. Am. Chem.
(
̈
ACKNOWLEDGMENTS
■
Chem. 2014, 2014, 5296−303.
(
(
Chem. - Eur. J. 2013, 19, 13396−401.
(33) Prakash, G. K. S.; Panja, C.; Shakhmin, A.; Shah, E.; Mathew, T.;
Olah, G. A. J. Org. Chem. 2009, 74, 8659−68.
(
(
We thank the National Science Foundation (CHE 1361654)
for financial support of this work. This research made use of the
00 MHz NMR spectrometer of the Chemistry Department, an
NIH SIG (1S10OD012077-01A1).
31) Evans, D. F. J. Chem. Soc. 1959, 2003.
32) Bauer, J.; Braunschweig, H.; Horl, C.; Radacki, K.; Wahler, J.
̈
4
34) Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 877−910.
35) Herrmann, W. A.; Rohrmann, J.; Schafer, A. J. Organomet. Chem.
̈
REFERENCES
■
(
1) Winkler, J. R.; Gray, H. B. In Molecular Electronic Structures of
1
(
9
(
3
(
984, 265, c1−c5.
36) Angelici, R. J.; Gingerich, R. G. W. Organometallics 1983, 2, 89−
5.
37) Venturelli, A.; Rauchfuss, T. B.; Verma, A. K. Inorg. Chem. 1997,
6, 1360−5.
38) Goodman, J. T.; Rauchfuss, T. B. J. Am. Chem. Soc. 1999, 121,
Transition Metal Complexes I; Mingos, D. M. P., Day, P., Dahl, J. P.,
Eds.; Springer: Berlin, Heidelberg, 2012; Vol. 142, pp 17−28.
(
(
(
3
(
2) Vicic, D. A.; Jones, W. D. J. Am. Chem. Soc. 1999, 121, 4070−1.
3) Berry, J. F. Comments Inorg. Chem. 2009, 30, 28−66.
4) Ray, K.; Heims, F.; Pfaff, F. F. Eur. J. Inorg. Chem. 2013, 2013,
784−807.
5) Hay-Motherwell, R. S.; Wilkinson, G.; Hussain-Bates, B.;
Hursthouse, M. B. Polyhedron 1993, 12, 2009−12.
6) Poverenov, E.; Efremenko, I.; Frenkel, A. I.; Ben-David, Y.;
Shimon, L. J. W.; Leitus, G.; Konstantinovski, L.; Martin, J. M. L.;
Milstein, D. Nature 2008, 455, 1093−6.
7) Jenkins, D. M.; Betley, T. A.; Peters, J. C. J. Am. Chem. Soc. 2002,
24, 11238−9.
8) Shay, D. T.; Yap, G. P. A.; Zakharov, L. N.; Rheingold, A. L.;
Theopold, K. H. Angew. Chem., Int. Ed. 2005, 44, 1508−10.
9) Mindiola, D. J.; Hillhouse, G. L. J. Am. Chem. Soc. 2002, 124,
976−7.
10) Waterman, R.; Hillhouse, G. L. J. Am. Chem. Soc. 2003, 125,
3350−1.
11) Jones, C.; Schulten, C.; Rose, R. P.; Stasch, A.; Aldridge, S.;
5
(
017−22.
39) Kawaguchi, H.; Tatsumi, K. J. Am. Chem. Soc. 1995, 117, 3885−
6
.
(
(40) Kawaguchi, H.; Yamada, K.; Lang, J.-P.; Tatsumi, K. J. Am.
Chem. Soc. 1997, 119, 10346−58.
́
(
41) Pino-Chamorro, J. A.; Algarra, A. G.; Fernan
Hernandez-Molina, R.; Basallote, M. G. Inorg. Chem. 2013, 52,
4334−42.
42) DuBois, M. R. Chem. Rev. 1989, 89, 1−9.
43) Smiles, D. E.; Wu, G.; Hayton, T. W. J. Am. Chem. Soc. 2014,
36, 96−9.
44) Smiles, D. E.; Wu, G.; Kaltsoyannis, N.; Hayton, T. W. Chem.
Sci. 2015, 6, 3891−9.
45) Hamada, S.; Funasako, Y.; Mochida, T.; Kuwahara, D.; Yoza, K.
J. Organomet. Chem. 2012, 713, 35−41.
́
dez-Trujillo, M. J.;
(
1
(
́
1
(
(
1
(
9
(
1
(
(
(
Woodul, W. D.; Murray, K. S.; Moubaraki, B.; Brynda, M.; La Macchia,
G.; Gagliardi, L. Angew. Chem., Int. Ed. 2009, 48, 7406−10.
(
12) King, E. R.; Sazama, G. T.; Betley, T. A. J. Am. Chem. Soc. 2012,
1
34, 17858−61.
13) Mindiola, D. J.; Waterman, R.; Iluc, V. M.; Cundari, T. R.;
Hillhouse, G. L. Inorg. Chem. 2014, 53, 13227−38.
14) Cundari, T. R.; Jimenez-Halla, J. O. C.; Morello, G. R.; Vaddadi,
S. J. Am. Chem. Soc. 2008, 130, 13051−8.
15) Iluc, V. M.; Hillhouse, G. L. J. Am. Chem. Soc. 2010, 132,
5148−50.
16) Iluc, V. M.; Miller, A. J. M.; Anderson, J. S.; Monreal, M. J.;
Mehn, M. P.; Hillhouse, G. L. J. Am. Chem. Soc. 2011, 133, 13055−63.
17) Kogut, E.; Wiencko, H. L.; Zhang, L.; Cordeau, D. E.; Warren,
T. H. J. Am. Chem. Soc. 2005, 127, 11248−9.
18) Iluc, V. M.; Hillhouse, G. L. J. Am. Chem. Soc. 2014, 136, 6479−
8.
19) Scheibel, M. G.; Wu, Y.; Stu
Stalke, D.; de Bruin, B.; Schneider, S. J. Am. Chem. Soc. 2013, 135,
7719−22.
20) Zolnhofer, E. M.; Kaß
W.; Maron, L.; van Gastel, M.; Bill, E.; Meyer, K. J. Am. Chem. Soc.
014, 136, 15072−8.
21) Vreeken, V.; Siegler, M. A.; de Bruin, B.; Reek, J. N. H.; Lutz,
M.; van der Vlugt, J. I. Angew. Chem., Int. Ed. 2015, 54, 7055−9.
22) Scheibel, M. G.; Askevold, B.; Heinemann, F. W.; Reijerse, E. J.;
de Bruin, B.; Schneider, S. Nat. Chem. 2012, 4, 552−8.
23) Hartmann, N. J.; Wu, G.; Hayton, T. W. Angew. Chem., Int. Ed.
015, 54, 14956−9.
24) Hartmann, N. J.; Wu, G.; Hayton, T. W. Dalton Trans. 2016, 45,
4508−10.
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(
(
1
(
(
(
8
(
̈
ckl, A. C.; Krause, L.; Carl, E.;
1
(
̈
, M.; Khusniyarov, M. M.; Heinemann, F.
2
(
(
(
2
(
1
E
DOI: 10.1021/acs.organomet.7b00123
Organometallics XXXX, XXX, XXX−XXX