Small-molecule activation mediated by a uranium bipyridyl metallocene

Article abstract of DOI:10.1021/acs.organomet.7b00064

Addition of potassium graphite (KC₈) to a solution of (η⁵-C₅Me₅)₂UCl₂ (1) and 2,2'-bipyridine (bipy) gives the uranium bipyridyl metallocene (η⁵-C₅Me₅)₂U(bipy) (2) in good yield. In complex 2 a bipy radical anion is coordinated to a U(III) atom, and it is therefore an ideal starting material for small-molecule activation: e.g., it serves as a synthetic equivalent for the (η⁵-C₅Me₅)₂U^II fragment on treatment with conjugated alkynes and a variety of heterounsaturated molecules such as imines, carbodiimide, organic azides, hydrazine, and azo derivatives. Alternatively, it may also react with aldehydes, ketones, nitriles, and α,β-unsaturated reagents such as p-ClPhCHO, (CH₂)₅CO, PhCN, and methyl methacrylate (MMA), forming the C-C bond coupling products (η⁵ - C₅Me₅)₂U[(bipy)(p-ClPhCHO)] (10), (η⁵-C₅Me₅)₂U[(bipy){(CH₂)₅CO}] (11), (η⁵-C₅Me₅)₂U[(bipy)(PhCN)] (12), (η⁵-C₅Me₅)₂U[(bipy){CH₂=C(Me)CO(OMe)] (13a), and [(η⁵-C₅Me₅)₂U{OC(OMe)=C(Me)CH₂-3-bipy}]₂ (13b), respectively, in quantitative conversion. Furthermore, addition of CuI to complex 2 induces a single-electron-transfer process to form the uranium(III) iodide complex (η⁵-C₅Me₅)₂U(I)(bipy) (14).

Full text of DOI:10.1021/acs.organomet.7b00064

Article
pubs.acs.org/Organometallics
Small-Molecule Activation Mediated by a Uranium Bipyridyl
Metallocene
Lei Zhang, Congcong Zhang, Guohua Hou, Guofu Zi,*,† and Marc D. Walter*,‡
†
†
†
†
Department of Chemistry, Beijing Normal University, Beijing 100875, China
‡
Institut fu
̈
r Anorganische und Analytische Chemie, Technische Universitat
̈
Braunschweig, Hagenring 30, 38106 Braunschweig,
Germany
*
S Supporting Information
5
ABSTRACT: Addition of potassium graphite (KC ) to a solution of (η -
8
C Me ) UCl (1) and 2,2′-bipyridine (bipy) gives the uranium bipyridyl
5
5
2
2
5
metallocene (η -C Me ) U(bipy) (2) in good yield. In complex 2 a bipy radical
5
5 2
anion is coordinated to a U(III) atom, and it is therefore an ideal starting material
5
for small-molecule activation: e.g., it serves as a synthetic equivalent for the (η -
II
C Me ) U fragment on treatment with conjugated alkynes and a variety of
5
5 2
heterounsaturated molecules such as imines, carbodiimide, organic azides, hydrazine,
and azo derivatives. Alternatively, it may also react with aldehydes, ketones, nitriles, and α,β-unsaturated reagents such as p-
5
ClPhCHO, (CH ) CO, PhCN, and methyl methacrylate (MMA), forming the C−C bond coupling products (η -
2
5
5
5
5
C Me ) U[(bipy)(p-ClPhCHO)] (10), (η -C Me ) U[(bipy){(CH ) CO}] (11), (η -C Me ) U[(bipy)(PhCN)] (12), (η -
5
5 2
5
5 2
2 5
5
5 2
5
C Me ) U[(bipy){CH C(Me)CO(OMe)] (13a), and [(η -C Me ) U{OC(OMe)C(Me)CH −3-bipy}] (13b), respec-
5
5 2
2
5
5 2
2
2
tively, in quantitative conversion. Furthermore, addition of CuI to complex 2 induces a single-electron-transfer process to form
5
the uranium(III) iodide complex (η -C Me ) U(I)(bipy) (14).
5
5 2
INTRODUCTION
report on some observations concerning the chemistry of the
■
5
uranium bipyridyl metallocene (η -C Me ) U(bipy) (2) in
5
5 2
Low-valent actinide compounds have sparked considerable
attention because of their ability to activate small molecules and
to accommodate multielectron-transfer processes. However,
highly unfavorable redox potentials make divalent actinide
complexes difficult synthetic targets, and only a limited number
of thoroughly characterized divalent actinide compounds have
small-molecule activation.
1
RESULTS AND DISCUSSION
■
Treatment of an excess of KC with a 1:1 mixture of 2,2′-
8
5
bipyridine and (η -C Me ) UCl (1) in toluene solution gives
5
5 2
2
5
2
the green bipyridyl metallocene (η -C Me ) U(bipy) (2) in
5 5 2
therefore been prepared. One strategy to overcome these
9
0% yield (Scheme 1). This approach obviates the previous
limitations is the in situ reduction of appropriate An(IV)
3
precursors, but species formed under these conditions are
3
Scheme 1
highly reactive and their reactivity can be difficult to control.
An alternative approach comprises well-defined organometallic
complexes that can serve as synthons for the intrinsic reactivity
of these difficult to access oxidation states. In this context,
4
redox-active ligands such as 2,2′-bipyridine, 1,4-diazabuta-
5
6
7
diene, pyridine diimine, and arenes are ideal, since they can
“store” electrons and can provide them to the actinide atom
when required. For example, Gambarotta demonstrated that
naphthalene can be employed as a redox-active ligand to
prepare well-characterized thorium arene complexes which act
need for sodium amalgam and a uranium(III) starting
4i,q
7c,d
material. In contrast to a uranium(IV) complex containing
as sources for divalent thorium(II).
In the course of our
Ad,tBu
a bipyridyl dianion, [K(2.2.2-crypt)][((
(
ArO) tacn)U-
investigation, we have used diimine systems such as 2,2′-
3
4y
bipy)], complex 2 is best described as a U(III) complex
bipyridine (bipy) for this purpose and reported the well-
5
with a bipyridyl radical anion. The electronic structure in 2 is
behaved thorium metallocenes [η -1,2,4-(Me C) C H ] Th-
(
(
3
3
5
2 2
5
5
supported by UV/vis and NIR spectroscopy and was
bipy), [η -1,3-(Me C) C H ] Th(bipy), and (η -C Me ) Th-
3 2 5 3 2 5 5 2
4q
4i
independently reported by Bart and Ephritikhine. The
bipy), in which a bipy dianion is coordinated to a Th(IV)
identity of 2, which was isolated from our synthetic procedure,
atom. These compounds enabled us to explore the reactivity of
II
8
the “Cp Th ” fragment, and we are now extending these
2
investigations to the related uranium compounds which have so
Received: January 26, 2017
4j,o,q
far not been studied extensively.
In this contribution, we
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.7b00064
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Organometallics
Article
1
4i,q,t
was confirmed by H NMR spectroscopy,
and variable-
Scheme 3
1
temperature (20−100 °C) H NMR investigations confirmed
that no bipy dissociation occurs when 2 is heated to 100 °C,
consistent with a strong coordination of the bipyridyl ligand to
the U(III) atom. Nevertheless, the bipyridyl ligand in 2 can be
exchanged with conjugated alkynes. For example, treatment of
2
with 1 equiv of RCCCCR releases bipy and forms the
5
4
metallacyclopentatrienes (η -C Me ) U[η -C (R) ] (R = Ph
5 5 2 4 2
9
a
9b
(3), Me Si (4) ) in quantitative conversion (Scheme 2). The
3
Scheme 2
5
of 2 with (Ph CN) gives the U(IV) diiminato complex (η -
2
2
9b,12
C Me ) U(NCPh ) (7)
in quantitative conversion
Scheme 3), for which the proposed reaction mechanisms are
5
5 2
2 2
(
1
assumed to be related to those outlined for the reaction with
identity of 3 and 4 was confirmed by comparison of their H
NMR spectra to the literature data. However, when complex 2
is treated with simple alkynes such as PhCCPh, MeC
CMe, and PhCCMe, no reaction occurs even when the
reaction mixture is heated at 100 °C for 1 week.
9
((p-tolyl)NCH) , and they are shown in the Supporting
2
Information. The identity of 5−7 was established by a
1
comparison of their H NMR spectroscopic data to those
9b
reported in the literature for these compounds.
Moreover, the anionic bipyridyl ligand in 2 is also exchanged
on addition of carbodiimides. For example, treatment of 2 with
N,N′-dicyclohexylcarbodiimide (DCC) gives the four-mem-
Nevertheless, complex 2 may also react with heterounsatu-
rated organic molecules via ligand exchange with concomitant
two-electron transfer. For example, complex 2 reacts with 2
equiv of the imine PhCHNPh to yield the five-membered
5
2
bered uranium heterocycle (η -C Me ) U[η -N(C H )C(
NC H )N(C H )] (8) (Scheme 4). Analogous to the
6 11 6 11
5
5 2
6
11
5
2
heterocyclic U(IV) complex (η -C Me ) U[η -N(Ph)CH(Ph)-
5
5 2
reaction with PhCHNPh, DCC exchanges bipyridyl ligand
CH(Ph)N(Ph)] (5), resulting from a two-electron-transfer
process inducing the bipyridyl replacement and C−C coupling
10
to give a metallaaziridine, which converts to an imido
complex by isonitrile C H NC dissociation. However, unlike
(Scheme 2). For the formation of 5 the following reaction
6
11
pathway may be proposed: the coordination of PhCHNPh
to 2 induces a two-electron transfer, for which the U(III) atom
and the bipyridyl radical anion provide two electrons. This
Scheme 4
2−
leads to the reduction of PhCHNPh to [PhCH−NPh] and
bipy dissociation to form a U(IV) metallaaziridine intermedi-
1
0
ate, which immediately couples with a second molecule of
PhCHNPh to give 5 (Scheme 2). A two-electron-transfer
process with concomitant bipy release is also observed in the
reaction of 2 with the diazabutadiene ((p-tolyl)NCH) , in
2
5
which the five-membered U(IV)-containing heterocycle (η -
2
C Me ) U[η -N(p-tolyl)CHCHN(p-tolyl)] (6) is formed
5
5 2
(
Scheme 3). We propose a sequence similar to that outlined for
the reaction with PhCHNPh; coordination of ((p-tolyl)N
CH) forms a U(IV) metallaaziridine complex and releases
2
1
0
bipy, which converts by a [1,3]-U migration to complex 6
Scheme 3). Alternatively, similar to mechanisms proposed for
the formation of the group 4 and ytterbium(III) diazabutadiene
(
1
1
complexes, formation of 6 may also proceed via a transient
2a,b
diazabutadiene U(II) adduct,
which undergoes instanta-
neous two-electron transfer to yield 6 (Scheme 3). Treatment
B
DOI: 10.1021/acs.organomet.7b00064
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Organometallics
the sterically more congested uranium imido complex [η -1,2,4-
Article
5
5
of the pyridine-stabilized imido complex (η -C Me ) U
5
5 2
13
14
(
Me C) C H ] UNMe, the Cp* derivative is less sterically
NPh(py) with PhN , the less sterically encumbered Cp*
3
3
5
2 2
3
hindered and can therefore immediately convert with a second
ligand and the absence of a coordinating solvent renders the
coordination sphere at the uranium atom open enough for a
molecule of DCC in a [2 + 2] cycloaddition reaction to 8
(Scheme 4). The molecular structure of 8 is shown in Figure 1.
second molecule of (p-tolyl)N
3
to coordinate, which forms 9
and N (Scheme 5). Complex 9 may also be accessed by the
reaction of 2 with bis(p-tolyl)diazene (Scheme 5). Similar to
the reaction with PhCHNPh, bis(p-tolyl)diazene exchanges
bipyridyl ligand to form a three-membered U(IV) metallacycle,
followed by two-electron transfer and N−N bond cleavage to
give the U(VI) diimido complex 9 (Scheme 5).
The U−N distances are 2.213(3) Å for N(1) and 2.265(3) Å
2
5
for N(3), which are comparable to those found in (η -
2
i
i
i
C Me ) U[η -N( Pr)C(N Pr)N( Pr)] (2.258(4) and
5
5 2
9
b
2
.218(4) Å).
However, in contrast to the reaction with the imine PhCH
NPh, the bipyridyl ligand in 2 cannot be exchanged by
aldehydes and ketones. Instead, treatment of 2 with 1 equiv of
5
p-ClPhCHO or cyclohexanone yields (η -C Me ) U[(bipy)(p-
5
5 2
5
ClPhCHO)] (10) and (η -C Me ) U[(bipy){(CH ) CO}]
5
5 2
2 5
(
11), respectively, in quantitative conversion (Scheme 6). As
Scheme 6
Figure 1. Molecular structure of 8 (thermal ellipsoids drawn at the
5% probability level). Selected bond lengths (Å) and angles (deg):
3
U−C(Cp) (av) 2.773(4), U−C(Cp) (range) 2.740(4)− 2.824(4), U−
Cp(cent) (av) 2.499(4), U−N(1) 2.213(3), U−N(3) 2.265(3), U−
C(27) 2.767(4); Cp(cent)−U−Cp(cent) 132.1(1), N(1)−U−N(3)
6
0.7(1).
Complex 2 also reacts with organic azides, e.g., it forms the
5
U(VI) bis-imido complex (η -C Me ) U[N(p-tolyl)] (9)
5
5 2
2
1
with (p-tolyl)N (Scheme 5). The H NMR spectroscopic data
3
Scheme 5
4q
suggested by Bart and co-workers, initial coordination of the
carbonyl-containing substrate to 2 via the carbonyl oxygen
atom induces a single-electron transfer (SET) from the
uranium(III) atom to the π* orbital of the CO group,
which oxidizes the U(III) in 2 to U(IV), to form the radical
1
2
•−
1
2
•−
anion [R R CO] . Finally, both radicals [R R CO] and
[
1
•
−
bipy] participate in a C−C coupling reaction to yield 10 and
1, respectively (Scheme 6). In a similar manner, organic
9
b
of 9 agree with those reported in the literature. In analogy to
nitriles such as PhCN can also interact with the bipyridyl
5
the reactions of the more sterically encumbered actinide
complexes [η -1,2,4-(Me C) C H ] An(bipy) (An = Th, U)
it is reasonable to assume that (p-tolyl)N3
exchanges the coordinated bipyridyl ligand in 2 to form initially
moiety to yield (η -C Me ) U[(bipy)(PhCN)] (12) (Scheme
5
5 2
5
6). Moreover, the reaction of 2 with the α,β-unsaturated
3
3
5
2 2
4
j,8a
with (p-tolyl)N3,
reagent methyl methacrylate (MMA) produces a mixture of the
5
isomers (η -C Me ) U[(bipy){CH C(Me)CO(OMe)]
5
5
2
2
5
5
the uranium(IV) imido species (η -C Me ) UN(p-tolyl)
(13a) and [(η -C Me ) U{OC(OMe)C(Me)CH −3-
5
5 2
5
5
2
2
accompanied by N loss. However, in analogy to the reaction
bipy}] (13b) in quantitative conversion (Schemes 7 and 8).
2
2
C
DOI: 10.1021/acs.organomet.7b00064
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Organometallics
Article
Scheme 7
(Scheme 7). Alternatively, when the CO bond is reduced, an
enolyl radical (B) ensues, which immediately couples with
bipyridyl moiety to give a U(IV) complex. In a next step, this
complex then converts to a diradical species, which dimerizes to
the final product 13b (Scheme 8). Presumably, the selectivity-
determining step for the formation of 13a,b is the radical
coupling event: i.e., for 13a the formation of a five-membered
ring occurs with a slightly reduced barrier in comparison to the
formation of 13b, which yields a less favorable eight-membered
ring. The molecular structure of 13b is shown in Figure 2. The
Scheme 8
Figure 2. Molecular structure of 13b (thermal ellipsoids drawn at the
3
5% probability level). Selected bond lengths (Å) and angles (deg):
U−C(Cp) (av) 2.878(5), U−C(Cp) (range) 2.763(5)−2.947(5), U−
Cp(cent) (av) 2.614(5), U−N(1) 2.611(4), U−N(2) 2.451(4), U−O
2
.200(3); Cp(cent)−U−Cp(cent) 128.6(1), N(1)−U−N(2) 65.9(1).
relatively long U−N(1) distance of 2.611(4) Å is consistent
with a datively coordinated nitrogen atom. While the U−N(2)
distance of 2.451(4) Å is shorter than the distance of U−N(1)
(
2.611(4) Å), it is longer than those found in uranium(IV)
5
15
amide complexes, e.g., (η -C H ) UNPh (2.29(1) Å) and
(
5
5 3
2
5
16
η -C Me ) U[NH(2,6-Me C H )] (2.267(6) Å), presum-
5 5 2 2 6 3 2
ably because of the steric hindrance of the more bulky chelate
amido ligand. In addition, the U−O distance of 2.200(3) Å is
5
i
longer than those found in (η -C Me ) U(O-2,6- Pr -C H )I
5
5 2
2
6
3
1
7
5
i
(
(
2.114(6) Å)1 and (η -C Me ) U(O-2,6- Pr -C H )CH
5
5
2
2
6
3
3
8
2.126(4) Å). These structural parameters are comparable
5
4q
to those found in (η -C Me ) U[(bipy)(p-MePhCHO)].
5
5 2
Complex 2 can also be oxidized in a SET process by metal
halides such as CuI. Addition of 1 equiv of CuI to 2 affords the
5
19
uranium(III) iodide complex (η -C Me ) U(I)(bipy) (14) in
5
5 2
quantitative conversion (Scheme 6), in which bipy serves as a
4i
neutral ligand. The molecular structure of 14 is shown in
Figure 3. The U−N distances are 2.721(4) Å for N(1) and
2
.592(4) Å for N(2), whereas the U−I distance is 3.176(5) Å.
The relevant C(25)−C(26) distance of 1.467(7) Å is clearly
indicative of a neutral bipy ligand being coordinated to the
U(III) atom. Overall, these parameters are consistent with
4i
those previously reported by Ephritikhine and co-workers.
CONCLUSIONS
■
In conclusion, the reactivity of the uranium bipyridyl
5
metallocene (η -C Me ) U(bipy) (2) toward small molecules
5
5 2
The presence of the two isomers 13a,b in C D solution in a
was investigated. These studies established that, in analogy to
6
6
1
5
ratio of 3:1 can be verified by H NMR spectroscopy, but
unfortunately, this mixture cannot be converted to a single
isomer. In analogy to the formation of complexes 10 and 11,
complex 13a arises from the reduction of the CO bond
followed by radical (A) coupling with the bipyridyl moiety
the reactivity of the related thorium derivative (η -C Me ) Th-
5
5 2
8d
(bipy), the uranium complex 2 may serve as a synthetic
equivalent for the (η -C Me ) U fragment, as illustrated by its
5
II
5
5 2
reaction with unsaturated moleclules such as conjugated
alkynes, imines, carbodiimide, organic azides, hydrazine, and
D
DOI: 10.1021/acs.organomet.7b00064
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Organometallics
Article
EXPERIMENTAL SECTION
■
General Procedures. All reactions and product manipulations
were carried out under an atmosphere of dry dinitrogen with rigid
exclusion of air and moisture using standard Schlenk or cannula
techniques or in a glovebox. All organic solvents were freshly distilled
from sodium benzophenone ketyl immediately prior to use. 2,2′-
2
0
Bipyridine was purified by sublimation prior to use. KC , p-
8
2
1
5
9b,22
CH C H N , and (η -C Me ) UCl (1)
were prepared accord-
3
6
4
3
5
5
2
2
ing to literature methods. All other chemicals were purchased from
Aldrich Chemical Co. and Beijing Chemical Co. and used as received
unless otherwise noted. Infrared spectra were obtained from KBr
1
pellets on an Avatar 360 Fourier transform spectrometer. H and
13
1
C{ H} NMR spectra were at 25 °C recorded on a Bruker AV 400
spectrometer at 400 and 100 MHz, respectively. All chemical shifts are
reported in δ units and referenced to the residual protons of the
deuterated solvents, which are internal standards, for proton and
carbon chemical shifts. Melting points were measured on an X-6
melting point apparatus and were uncorrected. Elemental analyses
were performed on a Vario EL elemental analyzer. The bulk purity of
new compounds was established by NMR spectroscopy and elemental
analyses, unless stated otherwise.
Figure 3. Molecular structure of 14 (thermal ellipsoids drawn at the
5
Preparation of (η -C Me ) U(bipy) (2). KC (1.42 g, 10.5 mmol)
3
5% probability level). Selected bond lengths (Å) and angles (deg):
5
5 2
8
5
was added to a toluene (20 mL) solution of (η -C Me ) UCl (1; 2.00
U−C(Cp) (av) 2.813(5), U−C(Cp) (range) 2.758(5)−2.856(5), U−
5
5
2
2
g, 3.5 mmol) and 2,2′-bipyridine (bipy; 0.55 g, 3.5 mmol) with stirring
at room temperature. After this solution was stirred at 70 °C for 2
days, the suspension was filtered. The residue was washed with toluene
Cp(cent) (av) 2.541(5), U−N(1) 2.721(4), U−N(2) 2.592(4), U−I
3
.176(5), C(25)−C(26) 1.467(7); Cp(cent)−U−Cp(cent) 135.1(1),
N(1)−U−N(2) 61.1(1).
(5 mL × 3) and filtered. The combined filtrate was evaporated to
dryness, and the green powder was washed with n-hexane (10 mL × 2)
1
and dried under vacuum at 50 °C overnight. Yield: 2.09 g (90%). H
NMR (C D ): δ 0.14 (s, 30H), −19.94 (d, J = 9.1 Hz, 2H), −41.38 (s,
6
6
azo derivatives, in which the coordinated bipyridyl ligand was
readily exchanged during the reaction. Nevertheless, the
2
H), −81.28 (s, 2H) −93.81 (s, 2H) ppm. These spectroscopic data
4i,q,t,9b
were in agreement with those reported in the literature.
5
8d
5
electronic ground states in (η -C Me ) Th(bipy) and (η -
5
4
5
5 2
Preparation of (η -C Me ) U(η -C Ph ) (3). Method A. A
5 5 2 4 2
C Me ) U(bipy) are different. For Th, a bipy dianion
5
5
2
toluene (5 mL) solution of PhCCCCPh (81 mg, 0.4 mmol)
5
coordinates to a Th(IV) atom, whereas in the case of U a
bipyridyl radical anion is bound to a U(III) center. Hence, in a
two-electron-transfer process these electrons are provided
exclusively by the dianionic ligand in the case of Th, while
the two electrons for the related uranium compound are
provided by the U(III) atom and the bipyridyl radical anion.
Alternatively, similar to the reactivity of the thorium bipyridyl
was added to a toluene (10 mL) solution of (η -C Me ) U(bipy) (2;
5
5 2
266 mg, 0.40 mmol) with stirring at room temperature. After the
solution was stirred at 50 °C overnight, the solvent was removed. The
residue was extracted with benzene (10 mL × 3) and filtered. The
volume of the filtrate was reduced to 5 mL; brown microcrystals of 3
were isolated when this solution was kept at room temperature for 1
1
week. Yield: 213 mg (75%). H NMR (C D ): δ 6.69 (t, J = 7.0 Hz,
6
6
2
H), 5.18 (t, J = 6.8 Hz, 4H), 2.09 (m, 4H), −0.95 (s, 30H) ppm.
5
8d
complex (η -C Me ) Th(bipy), a C−C σ bond is formed on
5
5 2
These spectroscopic data agreed with those reported in the
literature.
reaction of 2 with the CO, CN, and CC−CO
functionalities of aldehydes, ketones, nitriles, and α,β-
unsaturated reagents. Moreover, complex 2 can also be oxidized
by metal halides such as CuI in a single-electron-transfer (SET)
process. In addition, the reactivity patterns observed in these
transformations are significantly influenced by the steric
demand of the cyclopentadienyl ligand. For example, mixing
9a,23
Method B. NMR Scale. A C D (0.3 mL) solution of PhCCC
6
6
CPh (4.0 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
5
charged with (η -C
(
Me
0.2 mL). Resonances of 3 and those of 2,2′-bipyridine ( H NMR
C D ): δ 8.72 (d, J = 8.0 Hz, 2H), 8.53 (d, J = 4.0 Hz, 2H), 7.22 (t, J
) U(bipy) (2; 13 mg, 0.02 mmol) and C D
5
5
2
6
6
1
(
6
6
1
=
1.8 Hz, 2H), 6.68 (m, 2H) ppm) were observed by H NMR
5
spectroscopy (100% conversion) when this solution was heated at 50
C overnight.
Preparation of (η -C Me ) U[η -C (SiMe ) ] (4). Method A.
of the more sterically hindered [η -1,2,4-(Me C) C H ] U-
3
3
5
2 2
°
(
bipy) with the organic azide (p-tolyl)N yields the imido
5
4
3
5
4j
5
5 2
4
3 2
complexes [η -1,2,4-(Me C) C H ] UN(p-tolyl), while
3
3
5
2 2
This compound was prepared as brown microcrystals from the
exposure of the less bulky 2 to (p-tolyl)N affords the U(VI)
5
3
reaction of (η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and
5
5 2
5
diimido complex (η -C Me ) U[N(p-tolyl)] (9). Further-
Me SiCCCCSiMe (78 mg, 0.40 mmol) in toluene (15 mL) at
5
5 2
2
3
3
more, we also observed a difference between the related
70 °C and recrystallization from an n-hexane solution by a procedure
5
1
uranium and thorium compounds: while the reaction of (η -
similar to that in the synthesis of 3. Yield: 225 mg (80%). H NMR
(
C D ): δ 2.17 (s, 18H), −2.45 (s, 30H) ppm. These spectroscopic
C Me ) Th(bipy) with imine PhCHNPh furnishes the
6
6
5
5 2
9b,24
5
8d
data were consistent with those reported in the literature.
Method B. NMR Scale. A C D (0.3 mL) solution of Me SiC
insertion product (η -C Me ) Th[(bipy)(PhCHNPh)], the
5
5 2
6
6
3
bipyridyl ligand in the related uranium derivative 2 is cleanly
2
−
CCCSiMe
(3.9 mg, 0.02 mmol) was slowly added to a J. Young
3
replaced by [PhCH−NPh] . The attenuated reactivity can be
5
NMR tube charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol)
5
5 2
attributed to the more covalent bonds formed between uranium
and C D (0.2 mL). Resonances of 4 and those of 2,2′-bipyridine were
9b
6
6
and the coordinated ligands. Further exploration of actinide
complexes with redox-noninnocent ligands such as 2,2′-
bipyridine is ongoing and the results will be reported in due
course.
1
observed by H NMR spectroscopy (100% conversion) when this
solution was heated at 70 °C overnight. However, when this resulting
solution was heated at 130 °C for 3 days, the resonances of 2 and
1
those of Me SiCCCCSiMe3 were observed by H NMR
3
E
DOI: 10.1021/acs.organomet.7b00064
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
24
spectroscopy (100% conversion), indicating that an equilibrium
C H N U: C, 57.69; H, 7.82; N, 5.18. Found: C, 57.73; H, 7.81; N,
39
63
3
between 2 + TMS C and 4+bipy exists in the C D solution.
5.15.
Method B. NMR Scale. A C D (0.3 mL) solution of DCC (8.2 mg,
2
4
6
6
5
2
Preparation of (η -C Me ) U[η -N(Ph)CH(Ph)CH(Ph)N(Ph)]
5
5 2
6
6
(
5). Method A. This compound was prepared as purple microcrystals
0.04 mmol) was slowly added to a J. Young NMR tube charged with
5
5
from the reaction of (η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and
(η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D (0.2 mL).
5
5
2
5
5
2
6
6
1
PhCHNPh (145 mg, 0.80 mmol) in toluene (15 mL) at room
temperature and recrystallization from a benzene solution by a
procedure similar to that in the synthesis of 3. Yield: 279 mg (80%).
Resonances of 8 and those of 2,2′-bipyridine and C H NC ( H NMR
6
11
(C D ): δ 3.13 (m, 1H, NCH), 1.85 (m, 2H, CH ), 1.58 (m, 2H,
6
6
2
1
CH ), 1.34 (m, 6H, CH ) ppm) were observed by H NMR
2
2
1
H NMR (C D ): δ 33.61 (s, 2H), 10.93 (s, 30H), 8.25 (br s, 4H),
spectroscopy (100% conversion).
6
6
5
6
.81 (s, 4H), 6.33 (s, 2H), 1.23 (s, 4H), 0.88 (s, 4H), −10.15 (s, 2H)
Reaction of (η -C Me ) U(bipy) (2) with DCC. NMR Scale. A
5
5 2
ppm. These spectroscopic data were consistent with those reported in
C D (0.2 mL) solution of DCC (4.1 mg, 0.02 mmol) was slowly
6
6
9b
5
the literature.
Method B. NMR Scale. A C D (0.3 mL) solution of PhCHNPh
added to a J. Young NMR tube charged with (η -C Me ) U(bipy) (2;
5 5 2
6
6
13 mg, 0.02 mmol) and C D (0.3 mL). Resonances of 8 along with
6
6
(
7.2 mg, 0.04 mmol) was slowly added to a J. Young NMR tube
those of unreacted 2 and 2,2′-bipyridine and C H NC were observed
6
11
5
1
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
by H NMR spectroscopy (50% conversion based on 2).
5
5
2
6
6
5
(
0.2 mL). Resonances of 5 and those of 2,2′-bipyridine were observed
Preparation of (η -C Me ) U[N(p-tolyl)] (9). Method A. This
5
5 2
2
1
by H NMR spectroscopy (100% conversion) when this solution was
kept at room temperature overnight.
compound was prepared as brown microcrystals from the reaction of
5
(η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and (p-tolyl)N (107
5
5
2
3
5
Reaction of (η -C Me ) U(bipy) (2) with PhCHNPh. NMR
mg, 0.80 mmol) in toluene (15 mL) at room temperature and
recrystallization from a benzene solution by a procedure similar to that
5
5 2
Scale. A C D (0.2 mL) solution of PhCHNPh (3.6 mg, 0.02
6
6
5
1
mmol) was slowly added to a J. Young NMR tube charged with (η -
C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D (0.3 mL).
in the synthesis of 3. Yield: 224 mg (78%). H NMR (C D ): δ 9.14
6
6
5
5
2
6
6
(d, J = 8.1 Hz, 4H), 7.59 (s, 6H), 4.10 (s, 30H), 2.70 (d, J = 8.1 Hz,
Resonances of 5 along with those of unreacted 2 and 2,2′-bipyridine
4
H) ppm. These spectroscopic data were in agreement with those
1
9b
were observed by H NMR spectroscopy (50% conversion based on
reported in the literatures.
2
) when this solution was kept at room temperature overnight.
Method B. NMR Scale. A C D (0.3 mL) solution of (p-tolyl)N
6
6
3
5
2
Preparation of (η -C Me ) U[η -N(p-tolyl)CHCHN(p-tolyl)]
5
5 2
(5.3 mg, 0.04 mmol) was slowly added to a J. Young NMR tube
(
6). Method A. This compound was prepared as brown microcrystals
from the reaction of (η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and
5
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
5
5
2
6
6
5
5
5
2
(0.2 mL). Resonances of 9 and those of 2,2′-bipyridine were observed
(
(p-tolyl)NCH) (94 mg, 0.40 mmol) in toluene (15 mL) at room
1
2
by H NMR spectroscopy (100% conversion).
temperature and recrystallization from a benzene solution by a
5
Reaction of (η -C Me ) U(bipy) (2) with (p-tolyl)N . NMR
5
5 2
3
procedure similar to that in the synthesis of 3. Yield: 268 mg (90%).
Scale. A C D (0.2 mL) solution of (p-tolyl)N (2.7 mg, 0.02 mmol)
was slowly added to a J. Young NMR tube charged with (η -
C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D (0.3 mL).
6
6
3
1
5
H NMR (C D ): δ 5.09 (s, 30H), 1.39 (s, 2H), 0.17 (s, 6H), −0.88
6
6
(
d, J = 7.6 Hz, 4H), −30.67 (s, 2H), −33.85 (br s, 2H). These
5
5
2
6
6
spectroscopic data were in agreement with those reported in the
literature.
Resonances of 9 along with those of unreacted 2 and 2,2′-bipyridine
9b
1
were observed by H NMR spectroscopy (50% conversion based on
Method B. NMR Scale. A C D (0.3 mL) solution of ((p-tolyl)N
2).
6
6
5
CH) (4.7 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
Reaction of (η -C Me ) U(bipy) (2) with Bis(p-tolyl)diazene.
NMR Scale. A C D (0.2 mL) solution of bis(p-tolyl)diazene (4.2 mg,
2
5
5 2
5
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
5
5
2
6
6
6 6
(
0.2 mL). Resonances of 6 and those of 2,2′-bipyridine were observed
0.02 mmol) was slowly added to a J. Young NMR tube charged with
1
5
by H NMR spectroscopy (100% conversion).
(η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D (0.3 mL).
5
5
2
6
6
5
1
Preparation of (η -C Me ) U(NCPh ) (7). Method A. This
Resonances of 9 and 2,2′-bipyridine were observed by H NMR
spectroscopy (100% conversion).
Preparation of (η -C Me ) U[(bipy)(p-ClPhCHO)] (10). Method
A. This compound was isolated as pink-red microcrystals from the
5
5 2
2 2
compound was prepared as brown microcrystals from the reaction of
5
5
(
η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and (Ph CN) (144
5
5
2
2
2
5
5 2
mg, 0.40 mmol) in toluene (15 mL) at 100 °C, and recrystallization
from a benzene solution by a procedure similar to that in the synthesis
5
reaction of (η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and p-
5 5 2
1
of 3. Yield: 320 mg (92%). H NMR (C D ): δ 7.69 (d, J = 6.8 Hz,
4
3
ClPhCHO (57 mg, 0.40 mmol) in toluene (15 mL) at room
temperature and recrystallization from a benzene solution by a
6
6
H), 7.35 (d, J = 7.4 Hz, 4H), 7.10 (m, 6H), 7.01 (m, 6H), −1.83 (s,
0H) ppm. These spectroscopic data were in agreement with those
procedure similar to that described in the synthesis of 3. Yield: 274 mg
9b,12
1
reported in the literatures.
(85%). Mp: 229−231 °C dec. H NMR (C
6
D
6
): δ 71.67 (s, 1H),
Method B. NMR Scale. A C D (0.3 mL) solution of (Ph CN)
54.06 (s, 1H), 24.28 (d, J = 8.7 Hz, 2H), 16.57 (s, 1H), 14.45 (d, J =
8.2 Hz, 1H), 13.27 (d, J = 9.1 Hz, 2H), 12.91 (d, J = 11.5 Hz, 1H),
7.35 (d, J = 9.7 Hz, 1H), 1.82 (s, 15H), 0.80 (s, 15H), −3.34 (s, 1H),
6
6
2
2
(
7.2 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
5
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
(
by H NMR spectroscopy (100% conversion) when this solution was
heated at 100 °C overnight.
5
5
2
6
6
13
1
0.2 mL). Resonances of 7 and those of 2,2′-bipyridine were observed
−6.51 (s, 1H), −6.88 (s, 1H) ppm. C{ H} NMR (C D ): δ 162.0,
6 6
1
153.3, 147.0, 146.6, 140.2, 137.8, 135.0, 128.5, 127.9, 117.4, 111.0,
−
1
95.6, 93.1, 58.9, 36.5, −39.8, −41.1 ppm. IR (KBr, cm ): ν 2964 (m),
1600 (m), 1471 (m), 1402 (s), 1261 (s), 1082 (s), 1024 (s), 1010 (s),
796 (s). Anal. Calcd for C H N ClOU: C, 55.19; H, 5.38; N, 3.48.
5
2
Preparation of (η -C Me ) U[η -N(C H )C(NC H )N-
C H )] (8). Method A. This compound was prepared as brown
6 11
5
5
5 2
6
11
6
11
(
37 43
2
crystals from the reaction of (η -C Me ) U(bipy) (2; 266 mg, 0.40
Found: C, 55.15; H, 5.41, N, 3.46.
5
5 2
mmol) and DCC (165 mg, 0.80 mmol) in toluene (15 mL) at room
temperature and recrystallization from an n-hexane solution by a
procedure similar to that in the synthesis of 3. Yield: 266 mg (82%).
Method B. NMR Scale. A C D (0.3 mL) solution of p-ClPhCHO
6
6
(2.8 mg; 0.02 mmol) was slowly added to a J. Young NMR tube
5
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
5
5
2
6
6
1
1
Mp: 208−210 °C dec. H NMR (C D ): δ 26.88 (s, 1H), 15.72 (s,
(0.2 mL). The resonances due to 10 were observed by H NMR
6
6
1
2
1
H), 5.78 (s, 2H), 5.40 (s, 1H), 5.22 (m, 3H), 5.00 (s, 30H), 4.16 (s,
H), 2.76 (m, 1H), 2.38 (s, 1H), 2.09 (s, 2H), 1.21 (s, 2H), 0.86 (s,
H), −5.61 (s, 1H), −7.13 (s, 2H), −7.45 (m, 3H), −9.69 (s, 1H),
spectroscopy (100% conversion).
5
Preparation of (η -C Me ) U[(bipy){(CH ) CO)] (11). Method
5
5 2
2 5
A. This compound was isolated as purple crystals from the reaction of
(η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and (CH ) CO (40 mg,
5
−
10.37 (s, 4H), −12.52 (s, 1H), −29.53 (s, 1H), −34.85 (s, 1H),
5
5
2
2 5
13
1
−
35.82 (s, 1H), −47.44 (s, 1H) ppm. C{ H} NMR (C D ): δ 327.1,
0.40 mmol) in toluene (15 mL) at room temperature and
recrystallization from an n-hexane solution by a procedure similar to
that described in the synthesis of 3. Yield: 244 mg (80%). Mp: 218−
6
6
5
8.8, 50.9, 31.9, 28.2, 28.1, 23.0, 15.4, 14.3, 10.4, 4.9, −31.2 ppm. IR
−1
(
KBr, cm ): 2924 (s), 2848 (s), 1639 (s, CN), 1570 (s), 1444 (s),
1
1
402 (s), 1259 (s), 1097 (s), 1018 (s), 800 (s). Anal. Calcd for
220 °C dec. H NMR (C D ): δ 101.73 (s, 1H), 35.84 (m, 1H), 35.27
6
6
F
DOI: 10.1021/acs.organomet.7b00064
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(
2
1
m, 1H), 34.64 (m, 1H), 30.78 (s, 1H), 27.61 (s, 1H), 27.31 (m, 1H),
6.25 (s, 1H), 18.76 (m, 1H), 18.43 (s, 1H), 17.46 (m, 1H), 16.80 (m,
H), 16.24 (m, 1H), 16.10 (m, 1H), 13.51 (m, 1H), 0.14 (d, J = 5.72
2C H suitable for X-ray diffraction analysis were selected from those
microcrystals that recrystallized from a benzene solution at room
temperature.
6
6
Hz, 1H), −0.24 (s, 15H), −0.53 (s, 15H), −4.08 (s, 1H), −6.37 (s,
Method B. NMR Scale. A C D (0.3 mL) solution of MMA (2.0 mg,
0.02 mmol) was slowly added to a J. Young NMR tube charged with
6
6
H) ppm. 13C{ H} NMR (C D ): δ 157.5, 147.8, 128.9, 112.6, 111.8,
1
1
6
6
5
1
11.5, 111.3, 109.6, 99.4, 84.0, 73.8, 60.3, 52.5, 51.9, 51.4, 49.8, 45.1,
44.7, −50.7 ppm. IR (KBr, cm ): ν 2924 (s), 2852 (s), 1600 (s),
(η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D (0.2 mL).
5
5
2
6
6
−1
1
−
Resonances of 13a,b were observed by H NMR spectroscopy (100%
conversion) when this solution was kept at room temperature
overnight. The 13a/13b ratio is ca. 3/1. The sample was monitored
periodically by H NMR spectroscopy, but no changes in the H NMR
spectrum were observed on heating at 100 °C for 1 week, indicating
that the mixture of 13a and 13b could not be converted to a single
isomer.
1
471 (s), 1446 (s), 1369 (s), 1276 (s), 1141 (s), 1033 (s), 964 (s), 748
(
s). Anal. Calcd for C H N OU: C, 56.68; H, 6.34; N, 3.67. Found:
36 48 2
1
1
C, 56.65; H, 6.36; N, 3.65. This complex was also characterized by X-
ray diffraction analysis, and its molecular structure is shown in the
Supporting Information: The quality of the data was rather poor
because of crystal twinning but was sufficient to establish the overall
connectivity.
5
19
Preparation of (η -C
compound was isolated as black crystals from the reaction of (η -
Me
)
U(I)(bipy) (14). Method A. This
5
5
2
5
Method B. NMR Scale. A C D (0.3 mL) solution of (CH ) CO
6
6
2 5
(
2.0 mg; 0.02 mmol) was slowly added to a J. Young NMR tube
C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and CuI (77 mg, 0.40
5 5 2
5
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
mmol) in benzene (15 mL) at 80 °C and recrystallization from a
5
5
2
6
6
1
(
0.2 mL). The resonances due to 11 were observed by H NMR
benzene solution by a procedure similar to that described in the
1
spectroscopy (100% conversion).
synthesis of 3. Yield: 261 mg (80%). Mp: 238−240 °C dec. H NMR
5
Preparation of (η -C Me ) U[(bipy)(PhCN)] (12). Method A.
(C D ): δ 31.34 (s, 1H), 16.41 (s, 1H), 5.88 (s, 30H), 2.13 (s, 1H),
6 6
5
5 2
This compound was isolated as brown microcrystals from the reaction
0.48 (s, 1H), −0.66 (s, 1H), −5.25 (s, 1H), −36.36 (s, 36), −39.60 (s,
5
−1
of (η -C Me ) U(bipy) (2; 266 mg, 0.40 mmol) and PhCN (41 mg,
1H) ppm. IR (KBr, cm ): ν 2904 (m), 1595 (s), 1435 (s), 1383 (s),
5
5 2
1
4
155 (m), 1060 (s), 1014 (s), 879 (s). Anal. Calcd for C H IN U: C,
0
.40 mmol) in benzene (15 mL) at room temperature and
30 38 2
5.52; H, 4.84; N, 3.54. Found: C, 45.54; H, 4.86; N, 3.47.
recrystallization from a benzene solution by a procedure similar to
Method B. NMR Scale. CuI (3.8 mg, 0.02 mmol) was slowly added
that described in the synthesis of 3. Yield: 261 mg (85%). Mp: 215−
5
1
to a J. Young NMR tube charged with (η -C Me ) U(bipy) (2; 13 mg,
2
1
1
1
1
17 °C. H NMR (C D ): δ 46.32 (s, 1H), 13.51 (s, 1H), 13.11 (s,
5
5 2
6
6
0
.02 mmol) and C D (0.5 mL). The resonances due to 14 were
H), 10.15 (s, 1H), 9.80 (s, 1H), 9.35 (s, 2H), 5.60 (s, 2H), 4.74 (s,
H), 2.10 (s, 1H), 1.83 (s, 15H), 1.38 (s, 15H), 0.09 (s, 1H), −5.24 (s,
H) ppm. 13C{ H} NMR (C D ): δ 187.0, 169.9, 156.3, 156.0, 141.8,
6 6
1
observed by H NMR spectroscopy (100% conversion) when this
1
solution was heated at 80 °C for 2 h.
6
6
5
Reaction of (η -C Me ) U(bipy) (2) with PhCCPh, MeC
29.2, 128.8, 128.5, 115.6, 101.8, 95.6, 89.3, 85.3, 61.0, −37.8, −40.3
5
5 2
−
1
CMe, or PhCCMe. NMR Scale. An excess amount of PhCCPh,
ppm; other carbons overlapped. IR (KBr, cm ): ν 2964 (s), 2899 (s),
604 (s), 1465 (s), 1446 (s), 1261 (s), 1095 (s), 1022 (s), 796 (s).
Anal. Calcd for C H N U: C, 57.88; H, 5.64; N, 5.47. Found: C,
MeCCMe, or PhCCMe was added to a J. Young NMR tube
1
5
charged with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D
5
5
2
6
6
37
43
3
1
(
0.5 mL). In each case, the sample was monitored periodically by H
NMR spectroscopy. No changes in the H NMR spectrum were
observed on heating at 100 °C for 1 week.
5
7.92; H, 5.66, N, 5.45.
Method B. NMR Scale. A C D (0.3 mL) solution of PhCN (2.1
1
6
6
mg, 0.02 mmol) was slowly added to a J. Young NMR tube charged
5
X-ray Crystallography. Single-crystal X-ray diffraction measure-
ments were carried out on a Rigaku Saturn CCD diffractometer at
00(2) K using graphite-monochromated Mο Kα radiation (λ =
with (η -C Me ) U(bipy) (2; 13 mg, 0.02 mmol) and C D (0.2 mL).
5
5
2
6
6
1
The resonances due to 12 were observed by H NMR spectroscopy
100% conversion).
Preparation of (η -C Me ) U[(bipy){CH C(Me)CO(OMe)]
1
(
5
0.71073 Å) or Cu Kα radiation (λ = 1.54184 Å). An empirical
5
5 2
2
25
5
absorption correction was applied using the SADABS program. All
(
13a) and [(η -C Me ) U{OC(OMe)C(Me)CH -3-bipy}] (13b).
5
5 2
2
2
structures were solved by direct methods and refined by full-matrix
least squares on F2 using the SHELXL program package. All
hydrogen atoms were geometrically fixed using the riding model. The
crystal data and experimental data for 8, 13b, and 14 are summarized
in the Supporting Information.
Method A. A toluene (5 mL) solution of MMA (40 mg, 0.4 mmol)
26
5
was added to a toluene (10 mL) solution of (η -C Me ) U(bipy) (2;
5
5 2
2
66 mg, 0.40 mmol) with stirring at room temperature. After the
solution was stirred at room temperature overnight, the solvent was
removed. The residue was extracted with n-hexane (10 mL × 3) and
filtered. The volume of the filtrate was reduced to 5 mL. After this
solution was kept at room temperature for 1 week, brown-red
microcrystals were isolated. Yield: 229 mg (75%). The NMR spectrum
recorded in C D showed the presence of two isomers in a 3:1 ratio.
ASSOCIATED CONTENT
Supporting Information
■
*
S
6
6
1
The Supporting Information is available free of charge on the
ACS Publications Web site at DOI: 10.1021/xxxxx. (CIF) The
Supporting Information is available free of charge on the ACS
Publications website at DOI: 10.1021/acs.organomet.7b00064.
Data for 13a are as follows. H NMR (C D ): δ 54.46 (s, 1H), 25.50
6
6
(
s, 1H), 16.14 (s, 1H), 14.06 (d, J = 10.6 Hz, 1H), 13.69 (s, 3H), 10.30
(
1
s, 3H), 6.11 (d, J = 7.0 Hz, 1H), 3.88 (s, 15H), 2.19 (s, 1H), 1.50 (s,
5H), 1.09 (s, 1H), −0.94 (s, 1H), −3.69 (s, 1H), −20.00 (d, J = 10.6
13 1
Hz, 1H) ppm. C{ H} NMR (C D ): δ 198.6, 198.4, 156.1, 118.1,
6
6
Synthesis of 7, molecular structure of 11, and crystal
parameters for compounds 8, 13b, and 14 (PDF)
X-ray crystallographic data for compounds 8, 13b, and 14
1
16.0, 101.6, 101.5, 98.5, 98.4, 78.5, 78.2, 77.0, 65.6, 32.2, 29.4, −33.3,
1
−
44.1. Data for 13b are as follows. H NMR (C D ): δ 115.01 (s, 1H),
6 6
3
6
1
2.95 (s, 3H), 31.34 (s, 1H), 22.07 (d, J = 10.3 Hz, 1H), 20.09 (s, 3H),
(CIF)
.56 (s, 1H), 2.20 (d, J = 10.3 Hz, 1H), −0.06 (s, 15H), −0.86 (s,
5H), −3.44 (s, 1H), −3.65 (s, 1H), −4.87 (s, 1H), −8.93 (s, 1H),
1
−
24.00 (s, 1H) ppm. 13C{ H} NMR (C D ): δ 233.5, 163.2, 151.5,
6
6
AUTHOR INFORMATION
Corresponding Authors
*E-mail for G.Z.: gzi@bnu.edu.cn.
*E-mail for M.D.W.: mwalter@tu-bs.de.
■
1
2
34.7, 112.7, 109.7, 109.4, 107.5, 76.83, 76.76, 76.5, 70.3, 61.9, 43.4,
3.0, 20.3, 19.9, −46.0, −50.0.
The unambiguous assignment of the NMR resonances correspond-
ing to 13a,b is not a trivial task. However, isomers 13a,b are obtained
in different ratios (ca. 3:1) and therefore their NMR resonances
feature different intensities, and we used this information for the
assignment of the respective NMR resonances. In addition, complexes
ORCID
Guohua Hou: 0000-0002-3571-456X
Guofu Zi: 0000-0002-7455-460X
Marc D. Walter: 0000-0002-4682-8749
1
3a,b were not isolated as pure materials on a synthetic scale because
of their very similar solubilities. However, a few orange crystals of 13b·
G
DOI: 10.1021/acs.organomet.7b00064
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Notes
Ascenso, J.; Santos, I. Inorg. Chem. 2004, 43, 6426−6434. (i) Mehdoui,
́ ̀
T.; Berthet, J.-C.; Thuery, P.; Salmon, L.; Riviere, E.; Ephritikhine, M.
The authors declare no competing financial interest.
Chem. - Eur. J. 2005, 11, 6994−7006. (j) Zi, G.; Jia, L.; Werkema, E. L.;
Walter, M. D.; Gottfriedsen, J. P.; Andersen, R. A. Organometallics
ACKNOWLEDGMENTS
■
2
005, 24, 4251−4264. (k) Spencer, L. P.; Schelter, E. J.; Yang, P.;
This work was supported by the National Natural Science
Foundation of China (Grant Nos. 21472013, 21672024), and
the Deutsche Forschungsgemeinschaft (DFG) through the
Heisenberg program (WA 2513/6).
Gdula, R. L.; Scott, B. L.; Thompson, J. D.; Kiplinger, J. L.; Batista, E.
R.; Boncella, J. M. Angew. Chem., Int. Ed. 2009, 48, 3795−3798.
(l) Spencer, L. P.; Yang, P.; Scott, B. L.; Batista, E. R.; Boncella, J. M.
Inorg. Chem. 2009, 48, 11615−11623. (m) Takase, M. K.; Fang, M.;
Ziller, J. W.; Furche, F.; Evans, W. J. Inorg. Chim. Acta 2010, 364, 167−
1
1
71. (n) Kraft, S. J.; Fanwick, P. E.; Bart, S. C. Inorg. Chem. 2010, 49,
103−1110. (o) Kraft, S. J.; Walensky, J.; Fanwick, P. E.; Hall, M. B.;
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DOI: 10.1021/acs.organomet.7b00064
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DOI: 10.1021/acs.organomet.7b00064
Organometallics XXXX, XXX, XXX−XXX