Small molecule activation by mixed methyl/methylidene rare earth metal complexes

Article abstract of DOI:10.1039/c6dt00314a

Diverse reactivity patterns of mixed tetramethyl/methylidene rare-earth complexes bearing bulky benzamidinate coligands L₃Ln₃(μ₂-Me)₃(μ₃-Me)(μ₃-CH₂) [L = [PhC(NC₆H₃ⁱPr₂-2,6)₂]^-; Ln = Y(1a), Lu(1b)] with PhCN, alkynes, and CS₂ have been established. Reaction of complexes 1 with PhCN gave the μ₃-CH₂ addition complexes (NCN^dipp)₃Lu₃(μ₂-Me)₃(μ₃-Me)[μ-η¹:η¹:η³-CH₂C(Ph)N] [Ln = Y(2a), Lu(2b)]. Treatment of complexes 1 with phenylacetylene afforded unexpected alkenyl dianion complexes L₃Ln₃(μ₂-Me)₃(μ₃-Me)(μ-η¹:η³-PhC≡CMe) [Ln = Y(3a), Lu(3b)] through the insertion of rare earth methylidene into a C-H bond in a reductive fashion. However, reaction of complexes 1 and HC≡CSiMe₃ gave μ₃-Me protonolysis complexes L₃Ln₃(μ₂-Me)₃(μ₃-C≡CSiMe₃)(μ₃-CH₂) [Ln = Y (4a), Lu (4b)] in excellent yields. Treatment of complexes 1 with CS₂ led to the formation of the methyl activation complexes L₃Ln₃(μ₂-Me)₂(μ₃-CH₂)(μ₃-η¹:η²:η²-S₂C≡CH₂) [Ln = Y(5a), Lu(5b)]. All the new complexes were fully characterized.

Full text of DOI:10.1039/c6dt00314a

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Small molecule activation by mixed methyl/
methylidene rare earth metal complexes†
Cite this: DOI: 10.1039/c6dt00314a
Jianquan Hong, Zhenhua Li, Zhening Chen, Linhong Weng, Xigeng Zhou* and
Lixin Zhang*
Diverse reactivity patterns of mixed tetramethyl/methylidene rare-earth complexes bearing bulky benz-
amidinate coligands L3Ln3(μ2-Me)3(μ3-Me)(μ3-CH2) [L = [PhC(NC6H3 Pr2-2,6)2]−; Ln = Y(1a), Lu(1b)] with
i
PhCN, alkynes, and CS2 have been established. Reaction of complexes 1 with PhCN gave the μ3-CH2
addition complexes (NCNdipp)3Lu3(µ2-Me)3(µ3-Me)[µ–η1:η1:η3-CH2C(Ph)N] [Ln = Y(2a), Lu(2b)]. Treatment of
complexes 1 with phenylacetylene afforded unexpected alkenyl dianion complexes L3Ln3(μ2-Me)3-(μ3-Me)
(μ–η1:η3-PhCvCMe) [Ln = Y(3a), Lu(3b)] through the insertion of rare earth methylidene into a C–H bond in
a reductive fashion. However, reaction of complexes 1 and HCuCSiMe3 gave μ3-Me protonolysis com-
plexes L3Ln3(μ2-Me)3(μ3-CuCSiMe3)(µ3-CH2) [Ln = Y (4a), Lu (4b)] in excellent yields. Treatment of com-
plexes 1 with CS2 led to the formation of the methyl activation complexes L3Ln3(μ2-Me)2-(μ3-CH2)
(µ3–η1:η2:η2-S2CvCH2) [Ln = Y(5a), Lu(5b)]. All the new complexes were fully characterized.
Received 22nd January 2016,
Accepted 2nd March 2016
DOI: 10.1039/c6dt00314a
www.rsc.org/dalton
bonds. A significant challenge is the selective manipulation of
different ligands with apparently similar reactivities in these
Introduction
Metal Carbene/alkylidene complexes have received consider- reaction processes. Herein, we report the reactions between
able interest due primarily to their unique structural features the mixed tetramethyl/methylidene rare-earth complexes
and great potential as catalysts or useful intermediates in bearing bulky benzamidinate coligands L3Ln3(μ2-Me)3(μ3-Me)-
organic synthesis and polymerization.1,2 Despite significant (μ3-CH2) [L = [PhC(NC6H3 Pr2-2,6)2]−; Ln = Y(1a), Lu(1b)] with
i
recent advances in this area, the reaction chemistry of rare PhCN, alkynes, and CS2. It is worth noting that this is the first
earth metal methylidene complexes, especially multinuclear example of the insertion of a rare earth methylidene group
homometallic methylidene complexes, remains relatively (CH2) into a C–H bond in a reductive fashion, which provides
unexplored.3–8 Recently, we and others reported the syntheses a new route to alkenyl dianion complexes made possible by
of mixed methyl/methylidene rare earth metal clusters with reductant free reaction conditions. Furthermore, we demon-
different ancillary ligands, and discovered that the methylidene strate that rare earth methylidene 1 can react with CS2 to
group of these compounds can undergo a clean transfer with afford the product of a formal intermolecular CvC coupling
aromatic carbonyls to afford new oxo complexes and corres- without altering the trinuclear complex configuration under
ponding methylenation product olefins, and their reactivities mild conditions.
toward some organic molecules are influenced strongly by the
ancillary ligands.6b,7 Our recent works indicate that this type of
cluster is also a very good precursor for syntheses of the trinuc-
Results and discussion
Synthesis of mixed methyl/methylidene rare earth metal
lear rare earth imido, phosphinidene and their derivatives.7d,f
The insertion, protonolysis and metathesis of organic com-
pounds with organolanthanide complexes are regarded among
the most fundamental organometallic reactions and have been
attracting great interest as a basis for the rare earth metal-cata-
lyzed formations of carbon–carbon and carbon–heteroatom
trinuclear complexes
The homometallic trinuclear tetramethyl methylidene com-
plexes L3Ln3(μ2-Me)3(μ3-Me)(μ3-CH2) [L
i
=
[PhC(NC6H3 Pr2-
2,6)2]−; Ln = Y(1a), Lu(1b), Er(1c)] (Scheme 1) were prepared in
good yields via the previously reported method.7a All three
complexes were characterized fully. Complex 1c (X-ray structure
is shown in ESI†) is an isostructural compound of 1a and 1b.
It is also a thermally stable trinuclear complex with three
μ2-Me, one μ3-Me, and one μ3-CH2 bridges, all of whom are
very sensitive to moisture.
Department of Chemistry, Fudan University, Shanghai 200433, China.
E-mail: lixinzh@fudan.edu.cn, xgzhou@fudan.edu.cn; Fax: (+86) 21-5566-5702
†Electronic supplementary information (ESI) available. CCDC 1405778, 845812
and 845815–845817. For ESI and crystallographic data in CIF or other electronic
format see DOI: 10.1039/c6dt00314a
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Scheme 1 Syntheses of methylidene complexes 1.
Reactivity of rare earth metal tetramethyl methylidene
complexes towards PhCN
Fig. 1 13C (above) and 13C DEPT-135 (below) NMR spectra of 2a in
benzene-d6.
To explore their reactivities, firstly, we carried out the reaction
of complexes 1 with one equivalent of PhCN in toluene at
ambient temperature. The corresponding PhCN insertion pro-
ducts were obtained in excellent yields (Scheme 2). The 13C
and 13C DEPT-135 NMR spectra show that the signals of μ3-
CH2 disappear and the signal of the CH2 carbon of the CH2C-
(Ph)N groups is observed at δ = 85.9 ppm for 2a, and 86.9 ppm
for 2b (Fig. 1). The structural analysis of complex 2a suggests
that the newly formed 1-aza-allyl dianion ligand is coordinated
to the metal center through an η1:η1:η3 mode. The C6–N7
bond length (1.391 Å) of the 1-aza-allyl group is longer than
the normal CvN double bond distance (1.32 Å), while the C5–
C6 distance (1.389 Å) is between the values observed for a C–C
single bond and a CvC double bond, indicating that the two
negative charges are delocalized partially on the unit (see ESI,
Fig. S18†). Consistent with this, the average Y–N(1-aza-allyl)
bond distance of 2.338 Å is significantly shorter than the value
found
for
[K(DME)2(THF)3]-[Y2(μ-NHC6H3Me2-2,6)2(μ-Cl)-
(NHC6H3-Me2-2,6)4(THF)2], 2.470 Å.9 The Y2–N7 and Y3–N7
distances of 2.307 and 2.294 Å are approximately equivalent.
Obviously, this is in sharp contrast to the reaction of tran-
sition-metal carbene complexes with nitriles, wherein imido
complexes are generally formed (Fig. 2).2
In general, the transformation of alkynes to their alkene
derivatives is a useful methodology in organic synthesis. Of
particular importance is the reduction of alkynes to alkenyl
dianion intermediates that usually undergo further reaction
with electrophiles to yield a variety of functionalized alkenes.
Reduction of alkynes with low-valent metal species represents
a well-established pathway for the synthesis of alkenyl dianion
complexes. However, this method does not allow for simul-
taneous introduction of substituents; further, it requires the
use of strong reducing agents, which limits the scope of this
method. To the best of our knowledge, no example of a syn-
thesis of alkenyl dianion complexes directly from non-reduc-
tive metal complexes and alkynes has been reported.10,11
Reactivity of rare earth metal tetramethyl methylidene
complexes towards alkynes
Significantly, complexes 1 reacted with phenylacetylene to
form unexpected alkenyl dianion complexes L3Ln3(μ2-Me)3-
Fig. 2 Molecular structure of complex 2a with thermal ellipsoids at
30% probability. The benzamidinate ligands and the hydrogen atoms on
the phenyl ring are omitted for clarity.
Scheme 2 Reactions of complexes 1 with small molecules.
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(μ3-Me)(μ–η1:η3-PhCvCMe) [Ln = Y(3a), Lu(3b)] in high yields
through the insertion of rare earth methylidene into a C–H
bond in a reductive fashion. The formation of 3 was character-
1
ized clearly by NMR spectroscopy. In the H NMR spectra, the
signals of μ3-CH2 in complexes 1 disappeared, and signals at
2.32 ppm for 3a and 2.31 ppm for 3b, integrating to three
protons, can be assigned to the methyl group of the alkenyl
unit. The signals in the 13C NMR spectra of 3 at 217.7 and
150.7 ppm for 3a and 191.9 and 153.8 ppm for 3b can be
assigned to the two sp2 hybrid carbons of the alkenyl dianion.
These values are quite comparable with those in the complex
(C5Me5)2Lu(CHvC5Me4).12 The structure of complex 3b was
further confirmed by X-ray analysis (Fig. 3), revealing that the
formed cis-1-phenyl-1-propenyl dianion coordinated to the
Lu3+ ions in a μ3–η1:η3-bonding mode. The bond length of C6–
C7 is 1.279 Å, which represents an extremely short CvC
double bond (1.32–1.38 Å). The Lu–C7 (sp2) distance (2.332 Å)
is sharply shorter than the average Lu–C6 (sp2) distance
(2.500 Å) and Lu–C (sp2) distance (2.422 Å) in complex
(C5Me5)2Lu(CHvC5Me4).
Fig. 4 13C DEPT-135 (above) and 13C (below) NMR spectra of 4a in
benzene-d6.
Unexpectedly, protonolysis of μ3-Me instead of µ3-CH2 was
found in the reaction between 1 and HCuCSiMe3 at room
temperature, to give the selective μ3-methyl-displaced products
L3Ln3(μ2-Me)3(μ3-CuCSiMe3)(µ3-CH2) [Ln = Y (4a), Lu (4b)]
(Scheme 2). 4a (Fig. 4) and 4b were characterized by NMR
spectroscopy, elemental analyses, and 4a was further con-
firmed by X-ray diffraction determination (Fig. 6, and ESI†).
This is a rare example of a carbon atom with an sp
hybrid orbital working as a µ3-bridge in lanthanide chemistry
(Lu–C = 2.645 Å, CuC = 1.171 Å), usually existing as a
µ2-bridge.13
To explain the different reaction characteristics between
two kinds of alkynes, the reactions were further investigated by
theoretical calculations. As shown in Scheme 3, the addition of
phenylacetylene at the CH2 group in 1a generates an enthalpy
heat of 49.0 kcal mol−1, while the protonolysis of μ3-Me by
phenylacetylene releases 35.4 kcal mol−1 of enthalpy heat. The
results indicate that the reaction at the CH2 group is thermo-
dynamically more favorable than that at the CH3 group. In con-
trast to phenylacetylene, the reaction between 1a and
HCuCSiMe3 at the CH3 group is more thermodynamically
favorable than that at the CH2 group. These tendencies are
consistent with the experimental results.
Scheme 3 Theoretical calculations of enthalpy of reactions between 1a
and alkynes at the CH2 or Me groups.
Furthermore, steric factors should also be accounted for in
these reaction discrepancies. In the solid structure of 1a, the
steric hindrance of the groups surrounding CH2 is larger than
that of the μ3-Me group. Comparing to HCuCSiMe3, the
smaller steric hindrance of phenylacetylene, accompanied
with the π–π interaction of the phenyl rings from the phenyl-
acetylene and amidinate ligands, makes the reaction of phenyl-
acetylene with the CH2 group rather than the μ3-Me group
possible. In contrast, the large steric hindrance around the
Fig. 3 Molecular structures of complexes 3b and 4a with thermal ellip-
soids at 30% probability. The benzamidinate ligands and the hydrogen
atoms on phenyl ring are omitted for clarity.
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CH2 group impedes the bulky HCuCSiMe3 from reacting with 1,1-thiolate dianion ligand [S2CvCH2]2− is planar (∠C3–C2–S1
the CH2 group as well as the thermodynamic stability of the + ∠S1–C2–S2 + ∠C3–C2–S2 = 359.9°), and bridges three metal
forming product. Consequently, HCuCSiMe3 is ready to react ions through two sulfur atoms. The C2–C3 distance of 1.405 Å
with the μ3-Me group.
is at the high end of the range typical for C–C double bonds.16
The length of the C2–S1 bond (1.725 Å) is much shorter than
that of the C2–S2 bond (1.822 Å), probably due to the rigidity
Reactivity of rare earth metal tetramethyl methylidene
complexes with CS2
of
the
framework.
The
Lu–S1(bridging)
distances
(2.651–2.777 Å) are in the normal range.17
More interestingly, treatment of both 1a and 1b with one equi-
valent of CS2 at ambient temperature led to the formation of
the methyl activation products L3Ln3(μ2-Me)2(μ3-CH2)-
(µ3–η1:η2:η2-S2CvCH2) [Ln = Y(5a), Lu(5b)] in good yields
(Scheme 2), indicating that CS2 is attacked preferentially by the
methyl rather than the methylidene group, followed by C–H
activation of the involved methyl group, which reveals a novel
interesting reaction pattern of CS2 as a result of cooperative
action of the trinuclear metal centers. In many cases, the
insertion products have been obtained when CS2 was reacted
with metal alkyl or methylidene complexes.7f,h,14 The ethene-
1,1-dithiolate complex is unprecedented in organolanthanide
chemistry.15
In order to get a better insight into the formation mecha-
nism of 5, quantum chemical calculations were performed to
determine the intermediates and transition state structures
formed in the reaction between 1a1 and CS2 (Fig. 7). Geometry
optimization and harmonic vibrational frequency analysis
were performed with the M06-L18 density functional theory
(DFT) method. The M06-L functional has been proved to give
good overall results for many systems especially for those with
transition metals.19 The basis sets used were the SDD pseudo
potential20 for Y and Lu; the 6-31+G(d, p) basis set21 for the
N atoms, the C and S atoms of CS2, and the C and H atoms of
the methyl and methylene groups bonding with the metal
atoms; and the 6-31G basis set for the rest of the atoms that
are far away from the reaction center. To reduce the calculation
time, the L ligand was replaced by the [CH3C(NC6H5)2]−
ligand. All these calculations were performed with the Gaus-
sian 09 program.22
Complexes 5a and 5b (Fig. 5) were characterized by NMR
spectroscopy, elemental analyses, and complex 5b was further
analyzed by X-ray diffraction determination (Fig. 6, and ESI†).
The bond parameters of 5b indicate that the formed ethane-
The theoretical results indicate that the attacking of CS2
towards the methyl group is quite easy, and has an energy
barrier of 19.0 kcal mol−1 and a Gibbs free energy barrier of
26.5 kcal mol−1 at 298.15 K. The subsequent hydrogen transfer
from the methyl group of the formed CH3CS2 to an adjacent
methyl group bonding with the metal atoms is even faster, and
Fig. 5 13C DEPT-135 (above) and 13C (below) NMR spectra of 5b in
benzene-d6.
Fig. 7 Potential energy profile of the reaction between 1a1 and CS2.
The values in the plots are the relative energies at 0 K with zero-point
vibrational energy corrections. The values in the parentheses are relative
Gibbs free energies at 298.15 K calculated employing the rigid-rotor and
harmonic-vibrator approximation.
Fig. 6 Molecular structure of complex 5b with thermal ellipsoids at
30% probability. The benzamidinate ligands and hydrogen atoms are
omitted for clarity.
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1
has an energy barrier of just 12.0 kcal mol−1 and a Gibbs free 94%). H NMR (400 MHz, C6D6, RT): δ 7.22 (br d, 2H, Ar), 7.08
energy barrier of 13.2 kcal mol−1. Apparently, the attacking of (br m, 24H, Ar), 6.84 (t, J = 7.6 Hz, 1H, Ar), 6.60 (br m, 9H, Ar),
CS2 towards the methyl group is the rate-determining step. 6.30 (t, J = 7.4 Hz, 2H, Ar), 4.01 (d, J = 100 Hz, 2H, –CH2CN–),
Once this step happens, the resulting intermediate 2a2 will 3.41 (br s, 12H, –CHMe2), 1.13, 1.08 (m, 39H, –CHMe2 and
quickly transfer into 5a1 by releasing one methane molecule. µ3-CH3), 0.87 (d, J = 6.8 Hz, 36H, –CHMe2), 0.59 (br s, 9H,
The existence of intermediate 2a2 helps to explain the experi- µ2-CH3). 13C NMR (100 MHz, C6D6, RT): δ 174.2 (s, NCN), 174.1
mental results.
(s, NCN), 168.3 (s, –CH2CN–), 146.0 (s, Ar), 143.9 (s, Ar), 141.4
(s, Ar), 131.8 (s, Ar), 131.1 (s, Ar), 129.2 (s, Ar), 128.8 (s, Ar),
127.0 (s, Ar), 126.2 (s, Ar), 124.2 (s, Ar), 124.0 (s, Ar), 85.9 (s, –
CH2CN–), 29.8 (q, JYC = 8.4 Hz, µ3-CH3), 29.4 (t, JYC = 21.7 Hz,
µ2-CH3), 29.0 (br s, –CHMe2), 24.9 (s, –CHMe2), 23.4 (br s,
–CHMe2). Elemental Analysis: calcd (%) for C105H136N7Y3: C,
71.53; H, 7.78; N, 5.56. Found: C, 71.31; H, 7.96; N, 5.41.
Experimental
Materials and general processes
All manipulations were performed with rigorous exclusion of
air and water, using Schlenk techniques or a Mbraun glovebox
(Unilab Mbraun; <1 ppm O2, <1 ppm H2O). Toluene, THF and
hexane were distilled from sodium strip/benzophenone ketyl,
degassed, dried over fresh Na chips and stored in the glovebox.
Bis(2,6-diisopropylphenyl)carbodiimide was obtained from
Tokyo Chemical Industry Co., Ltd and used without purifi-
cation. CH3C6H4NMe2-o, N-benzylideneaniline, nBuLi (1.6 mol
L−1 in hexane), PhLi (2.0 mol L−1 in dibutyl ether) and AlMe3
(1 mol L−1 in heptane) were purchased from ACROS and used
without purification. Azobenzene was purchased from ALFA
AESAR and used without purification. C6D6 was obtained from
Cambridge Isotope and dried by sodium chips. CS2 was
(NCNdipp)3Lu3(µ2-Me)3(µ3-Me)[µ–η1:η1:η3-CH2C(Ph)N] (2b)
Complex 2b was obtained as a colorless crystalline product in
92% yield (0.186 g) from the treatment of (NCNdipp)3Lu3-
(µ2-Me)3(µ3-Me)(µ3-CH2) (0.192 g, 0.1 mmol) with 10 µL of
benzonitrile in toluene, similar to the preparation of 2a
1
described above. H NMR (400 MHz, C6D6, RT): δ 7.30 (br d,
2H, Ar), 7.08–6.97 (m, 24H, Ar), 6.86 (t, J = 7.4 Hz, 1H, Ar), 6.60
(br m, 9H, Ar), 6.29 (t, J = 7.8 Hz, 2H, Ar), 4.15 (d, J = 17.6 Hz,
2H, –CH2CN–), 3.51 (br m, 6H, –CHMe2), 3.35 (br m, 6H,
–CHMe2), 1.41 (s, 3H, µ3-CH3), 1.17, 1.05 (m, 45H, –CHMe2 and
µ-CH3), 0.86 (br s, 36H, –CHMe2). 13C NMR (100 MHz, C6D6,
RT): δ 173.7 (s, NCN), 169.2 (s, –CH2CN–), 145.7 (s, Ar), 144.3
(s, Ar), 143.5 (s, Ar), 141.8 (s, Ar), 141.6 (s, Ar), 131.9 (s, Ar),
131.2 (s, Ar), 129.3 (s, Ar), 128.4 (s, Ar), 127.0 (s, Ar), 126.8 (s,
Ar), 124.5 (s, Ar), 123.7 (br s, Ar), 86.9 (s, –CH2CN–), 34.3 (s, µ2-
CH3), 30.1 (s, µ3-CH3), 29.3 (s, –CHMe2), 28.4 (s, –CHMe2), 25.1
(s, –CHMe2), 24.6 (s, –CHMe2), 24.0 (s, –CHMe2), 22.8 (s,
–CHMe2). Elemental Analysis: calcd (%) for C105H136N7Lu3: C,
62.40; H, 6.78; N, 4.85. Found: C, 62.15; H, 6.93; N, 4.71.
23
obtained from ALFA AESAR and dried by CaH2. LnCl3 and
[(NCNdipp)Ln(CH2C6H4NMe2-o)2] (Ln = Y, Lu and Er)24 were
prepared according to literature procedures. H NMR and 13C
1
NMR spectra were recorded on a JEOL ECA-400 NMR spectro-
meter (FT, 400 MHz for H; 100 MHz for 13C) in C6D6 at room
1
temperature.
Typical experimental procedure for the synthesis of rare earth
metal methylidene complex (NCNdipp)3Er3(µ2-Me)3(µ3-Me)-
(µ3-CH2) (1c)
(NCNdipp)3Y3(µ-Me)3(µ3-Me)(µ–η1:η3-PhCvCMe) (3a)
2 mL of AlMe3/heptane solution (1 M, 2 mmol) was added
slowly to a stirring solution of [(NCNdipp)Er(CH2C6H4NMe2-o)2]
(0.875 g, 1 mmol) in toluene (15 mL). The solution was left to
stir for about 10 hours at ambient temperature. The toluene
was removed under vacuum, and an oily pink residue turned
to pink powder after washing with 2 mL of cold hexane twice.
The powder was dissolved in toluene again and the pink solu-
tion was concentrated under reduced pressure. The pink crys-
talline product of 1c can be obtained after standing at room
temperature for three days (0.442 g, 70%). Elemental Analysis:
calcd (%) for C98H131N6Er3: C, 62.12; H, 6.97; N, 4.44. Found:
C, 62.26; H, 7.19; N, 4.64.
To
(µ2-Me)3(µ3-Me)(µ3-CH2) (0.166 g, 0.1 mmol) was added slowly
toluene solution (5 ml) of phenylacetylene (11 µL,
a
stirring toluene solution (8 ml) of (NCNdipp)3Y3-
a
0.1 mmol). A color change from pale-yellow to brown-red was
observed after 30 minutes. The reaction solution was left to
stir for 10 hours and the solvent was removed under vacuum
and the oily brown-red residue turned to yellow powder
(0.164 g, 93%) after washing with 2 mL of cold hexane twice.
1H NMR (400 MHz, C6D6, RT): δ = 7.15 (br s, 6H, Ar), 7.03 (br s,
18H, Ar), 6.76 (br s, 4H, Ar), 6.61 (br s, 10H, Ar), 6.01 (br s, 2H,
Ar), 3.50 (br s, 12H, –CHMe2), 2.32 (s, 3H, –C(Ph)vCMe), 1.33
(br s, 3H, µ3-Me), 1.17 (d, J = 4.8 Hz, 36H, –CHMe2), 0.93 (d, J =
5.2 Hz, 36H, –CHMe2), 0.69 (s, 3H, µ2-CH3); 13C NMR (100 MHz,
(NCNdipp)3Y3(µ2-Me)3(µ3-Me)[µ–η1:η1:η3-CH2C(Ph)N] (2a)
A toluene solution (15 mL) of benzonitrile (10 µL, 0.1 mmol) C6D6, RT): δ = 217.7 (q, J = 6.5 Hz, –C(Ph)vC(Me)–), 175.2 (s,
was added slowly to a stirring toluene solution (20 mL) of NCN), 150.7, 143.4, 141.4, 132.3, 131.6, 130.8, 129.0, 128.5,
(NCNdipp)3Y3 (µ2-Me)3(µ3-Me)(µ3-CH2) (0.166 g, 0.1 mmol). The 126.7, 124.3, 123.9, 123.1, 122.4, 38.9 (q, J = 9.5 Hz, µ3-Me),
mixture was left to stir for about 24 hours at ambient tempera- 32.6 (t, J = 21.5 Hz, µ2-Me), 28.5 (s, –CHMe2), 25.0 (s, –CHMe2),
ture. The yellow solution was concentrated under vacuum to 23.3 (s, –CHMe2), 17.4 (s, –C(Ph)vCMe). Elemental Analysis:
saturation and yellow crystalline 2a was harvested after the calcd (%) for C106H137Y3N6: C, 72.26; H, 7.84; N, 4.77. Found:
solution stood for 4 days at ambient temperature (0.165 g, C, 71.92; H, 8.02; N, 4.56.
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(NCNdipp)3Lu3(µ-Me)3(µ3-Me)(µ–η1:η3-PhCvCMe) (3b)
Analysis: calcd (%) for C102H137N6SiLu3: C, 61.25; H, 6.90; N,
4.20. Found: C, 61.08; H, 7.13; N, 4.08.
Complex 3b was obtained as a yellow powder product (0.196 g,
97%), similarly to the preparation of 3a described above.
Yellow crystals were harvested by concentrating the toluene (NCNdipp)3Y3(µ2-Me)2(µ3-CH2)(µ2–η1:η2:η2-S2C2H2) (5a)
solution of 3b to saturation and leaving to stand at room temp-
A toluene solution of CS2 (6 µl, 0.1 mmol) was added slowly to
1
erature for 3 days. H NMR (400 MHz, C6D6, RT): δ = 7.13 (m,
a stirring toluene solution (20 mL) of (NCNdipp)3Y3(µ2-Me)3(µ3-
6H, Ar), 7.06 (br m, 22H, Ar), 6.90–6.80 (m, 4H, Ar), 6.61 (br s,
10H, Ar), 5.75 (d, J = 7.2 Hz, 2H, Ar), 3.52 (br s, 12H, –CHMe2),
Me)(µ3-CH2) (0.166 g, 0.1 mmol). The mixture was left to stir
overnight at ambient temperature. The solvent was removed
under vacuum and the oily brown-red residue was washed with
2 mL of cold hexane twice. 5a was obtained as a yellow powder
2.31 (s, 3H, –C(Ph)vCMe), 1.61 (s, 3H, µ3-Me), 1.14 (br d, 45H,
–CHMe2 and µ2-CH3), 0.90 (d, J = 6.8 Hz, 36H, –CHMe2), 13C
NMR (100 MHz, C6D6, RT): δ = 191.9 (s, –C(Ph)vCMe), 174.4
(0.131 g, 76%) after the hexane was removed under vacuum.
(s, NCN), 153.8 (s, –C(Ph)vCMe), 143.3 (br s, Ar), 141.7 (s, Ar),
1H NMR (400 MHz, C6D6, RT): δ 7.14–6.89 (m, 24H, Ar), 6.60
131.5 (s, Ar), 131.1 (s, Ar), 129.4 (s, Ar), 126.8 (s, Ar), 124.6 (s,
(m, 9H, Ar), 5.83 (s, 1H, –CvCH2), 5.55 (s, 1H, –CvCH2), 3.70
Ar), 124.1 (s, Ar), 122.1 (s, Ar), 121.4 (s, Ar), 39.4 (s, µ3-Me), 38.1
(m, 4H, –CHMe2), 3.43 (m, 8H, –CHMe2), 2.13 (s, 2H, µ3-CH2),
(s, µ2-Me), 28.4 (s, –CHMe2), 24.9 (s, –CHMe2), 23.4 (br s,
1.26 (d, J = 6.4 Hz, 24H, –CHMe2), 1.10 (m, 24H, –CHMe2), 0.90
–CHMe2), 16.0 (s, –C(Ph)vCMe). Elemental Analysis: calcd (%)
(m, 30H, –CHMe2 and µ2-Me). 13C NMR (100 MHz, C6D6, RT):
for C106H137Lu3N6: C, 63.02; H, 6.84; N, 4.16. Found: C, 63.46;
δ 176.4 (s, NCN), 174.5 (s, NCN), 155.8, 142.9, 142.0 (s, Ar),
141.5, 131.6, 131.2, 130.4, 130.1, 129.0, 126.9, 126.6, 124.9 (s,
H, 7.16; N, 3.95.
–CvCH2), 124.7, 124.6, 124.5, 124.4, 123.7, 123.6, 123.5, 116.7
(q, J = 22.8 Hz, µ3-CH2), 33.2 (t, J = 22.2 Hz, µ2-CH3), 28.7 (s, –
(NCNdipp)3Y3(µ2-Me)3(µ3-CH2)(µ3-CuCTMS) (4a)
A toluene solution (10 mL) of HCuCTMS (11 µL, 0.075 mmol) CHMe2), 28.5 (s, –CHMe2), 25.3 (s, –CHMe2), 25.1 (s, –CHMe2),
was added slowly to a stirring toluene solution (20 mL) of 23.3 (s, –CHMe2), 22.6 (s, –CHMe2). Elemental Analysis: calcd
(NCNdipp)3Y3(µ2-Me)3(µ3-Me)(µ3-CH2) (0.124 g, 0.075 mmol). A (%) for C98H127N6S2Y3: C, 68.44; H, 7.44; N, 4.89. Found: C,
color change of the solution was observed from pale-yellow to 68.76; H, 7.62; N, 4.67.
red in minutes then to yellow-green after one hour. The
mixture was left to stir for about 18 hours at ambient tempera-
ture, the toluene solvent was removed under vacuum and
complex 4a was obtained as a yellow powder quantitatively.
(NCNdipp)3Lu3(µ2-Me)2(µ3-CH2)(µ2–η1:η2:η2-S2C2H2) (5b)
Complex 5b was obtained as a yellow crystalline product in
72% yield (0.142 g) from the treatment of (NCNdipp)3Lu3(µ2-
Yellow crystalline 4a was harvested by recrystallization in
Me)3(µ3-Me)(µ3-CH2) (0.192 g, 0.1 mmol) with 6 µl of CS2 in
toluene at ambient temperature. 1H NMR (400 MHz, C6D6,
1
toluene, similar to the preparation of 5a described above. H
RT): δ 7.13 (m, 6H, Ar), 7.03 (m, 18H, Ar), 6.62 (m, 9H, Ar),
NMR (400 MHz, C6D6, RT): δ 6.94 (m, 24H, Ar), 6.54 (m, 9H,
3.61 (m, 12H, –CHMe2), 2.33 (q, JYH = 3.3 Hz, 2H, µ3-CH2), 1.31
Ar), 5.65 (s, 1H, –CvCH2), 5.36 (s, 1H, –CvCH2), 3.68 (m, 4H,
(d, J = 6.8 Hz, 36H, –CHMe2), 0.98(d, J = 6.8 Hz, 36H, –CHMe2),
–CHMe2), 3.39 (m, 8H, –CHMe2), 2.66 (s, 2H, µ3-CH2), 1.31 (s,
0.92 (s, 9H, µ2-CH3), −0.25 (s, 9H, –SiMe3). 13C NMR (100 MHz,
6H, µ2-CH3), 1.20 (d, J = 6.4 Hz, 24H, –CHMe2), 1.02 (br m,
C6D6, RT): δ 174.7 (s, NCN), 162.3 (q, JYC = 8.6 Hz, –
24H, –CHMe2), 0.82 (d, J = 6.0 Hz, 24H, –CHMe2). 13C NMR
(100 MHz, C6D6, RT): δ 176.1 (s, NCN), 173.9 (s, NCN), 152.2,
CuCSiMe3), 143.0 (s, Ar), 141.8 (s, Ar), 133.8 (s, –CuCSiMe3),
132.0 (s, Ar), 130.5 (s, Ar), 129.0 (s, Ar), 127.0 (s, Ar), 124.3 (s,
142.8, 142.4, 141.9, 131.9, 131.3, 130.6, 130.3, 129.3, 129.1,
Ar), 123.7 (s, Ar), 113.8 (d, JYC = 22.9 Hz, µ3-CH2), 33.6 (t, JYC
=
127.8 (s, –CvCH2), 127.0, 126.7, 124.7, 123.9, 123.7, 123.5,
119.1 (s, µ3-CH2), 38.6 (s, µ2-CH3), 28.6 (s, –CHMe2), 28.4 (s, –
CHMe2), 25.4 (s, –CHMe2), 25.2 (s, –CHMe2), 23.4 (s, –CHMe2),
22.9 (s, –CHMe2). Elemental Analysis: calcd (%) for
C98H127N6S2Lu3: C, 59.50; H, 6.47; N, 4.25. Found: C, 59.32; H,
6.58; N, 4.36.
22.5 Hz, µ2-CH3), 28.7 (s, –CHMe2), 26.1 (s, –CHMe2), 23.4 (s,
–CHMe2), −0.8(s, –SiMe3). Elemental Analysis: calcd (%) for
C102H137N6SiY3: C, 70.33; H, 7.93; N, 4.82. Found: C, 70.12; H,
8.12; N, 4.69.
(NCNdipp)3Lu3(µ2-Me)3(µ3-CH2)(µ3-CuCTMS) (4b)
Complex 4b was obtained as a yellow powder product quanti-
tatively, similarly to the preparation of 4a described above. H
1
Synthesis of cis-1-phenyl-1-propene
NMR (400 MHz, C6D6, RT): δ 7.14 (m, 6H, Ar), 7.04 (br s, 18H, An NMR tube equipped with a Teflon seal-cock was charged
Ar), 6.62 (m, 9H, Ar), 3.63 (m, 12H, –CHMe2), 2.77 (s, 2H, with 3b (0.058 g, 0.03 mmol) and benzene-d6 (0.50 mL). 5 μL
µ3-CH2), 1.44 (s, 9H, µ2-CH3), 1.30(br, 36H, –CHMe2), 0.96(d, of H2O (0.28 mmol) was injected into the yellow solution at
J = 7.2 Hz, 36H, –CHMe2), −0.27 (s, 9H, –SiMe3). 13C NMR room temperature. The NMR tube was shaken violently and a
(100 MHz, C6D6, RT): δ 173.9 (s, NCN), 162.0 (s, –CuCSiMe3), color change of the solution from yellow to colorless was
142.9 (s, Ar), 141.9 (s, Ar), 135.9 (s, –CuCSiMe3), 132.0 (s, Ar), observed in seconds. The formation of cis-1-phenyl-1-propene
1
130.6 (s, Ar), 129.1 (s, Ar), 126.9 (s, Ar), 124.3 (s, Ar), 123.7 (s, was confirmed by the H NMR signals appearing at δ 6.42 (d,
Ar), 112.3 (s, µ3-CH2), 38.9 (s, µ2-CH3), 28.4 (s, –CHMe2), 26.0
J = 12.0 Hz, 1H, PhCHvCHMe) and 5.65 (m, 1H,
(br s, –CHMe2), 23.4 (s, –CHMe2), −1.0 (s, –SiMe3). Elemental PhCHvCHMe), 1.70 (d, J = 7.2 Hz, 1H, PhCHvCHMe).
Dalton Trans.
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X-ray crystallographic analysis
Table 1 Selected bond lengths [Å] and angles [°] for complexes 2a, 3b,
4a and 5b
Suitable crystals were sealed in thin-wall glass capillaries
under a microscope in the glove box. Data collections were per-
formed on a Bruker SMART APEX (at 293 K) diffractometer
with a CCD area detector using graphite-monochromated Mo
Kα radiation (λ = 0.71073 Å). The determination of crystal class
and unit cell was carried out by the SMART program package.
The raw frame data were processed using SAINT25 and
SADABS26 to yield the reflection data file. The structure was
solved by using SHELXTL program.27 Refinement was per-
formed on F2 anisotropically by the full-matrix least-squares
method for all the non-hydrogen atoms. The analytical scatter-
ing factors for neutral atoms were used throughout the analy-
sis. Except for the hydrogen atoms on bridging-carbons,
hydrogen atoms were placed at the calculated positions and
included in the structure calculation without further refine-
ment of the parameters. The hydrogen atoms on bridging-
carbons were located by difference Fourier syntheses and their
coordinates and isotropic parameters were refined. The
residual electron densities were of no chemical significance.
Selected bond lengths and angles, and crystal and data collec-
tion parameters of complexes 1c, 2a, 3b, 4a and 5b are listed
in Tables 1 and 2, respectively. CCDC 1405778 (complex 1c),
845812 (complex 2a), 845817 (complex 3b), 845815 (complex
4a) and 845816 (complex 5b) contain the supplementary crys-
tallographic data for this paper.
2a
2.752(5)
3b
2.685(8)
2.600(8)
2.570(8)
2.467(7)
2.476(8)
2.429(8)
2.49(1)
4a
2.382(6)
5b
2.434(6)
2.396(6)
2.458(6)
2.657(13)
2.543(13)
2.529(9)
2.505(9)
Ln–Me/CH2 (µ3)
Ln–Me (µ2)
2.657(5)
2.641(5)
2.578(5)
2.541(5)
2.488(5)
2.490(6)
2.519(6)
2.533(5)
2.344(3)
2.427(4)
2.399(4)
2.322(3)
2.330(4)
2.413(4)
2.414(3)
2.307(3)
2.294(3)
2.418(6)
2.399(6)
2.537(7)
2.502(7)
2.486(6)
2.502(7)
2.552(6)
2.536(7)
2.415(5)
2.335(5)
2.350(5)
2.347(5)
2.425(5)
2.341(5)
2.652(7)
2.645(7)
2.637(7)
2.55(1)
2.407(8)
2.305(6)
2.396(6)
2.288(6)
2.304(6)
2.345(6)
2.295(6)
2.494(8)
2.527(8)
2.478(8)
Ln–Namidinate
2.333(6)
2.258(6)
2.283(6)
2.321(6)
2.348(6)
2.271(6)
Ln–N/C (µ3)
Ln–S (µ3)
—
—
—
—
—
—
2.683(5)
2.777(5)
2.651(4)
2.664(4)
2.641(5)
1.405(12)
—
—
—
—
—
—
—
—
—
—
—
Ln–C5/C2
C(2)–C(3)
C(5)–C(6)
C(6)–C(7)
2.645(4)
2.885(9)
—
1.55(1)
—
—
—
1.170(7)
—
—
—
1.28(1)
74.5(2)
76.3(2)
77.4(2)
81.7(2)
79.7(3)
83.3(2)
56.3(2)
58.3(2)
57.1(2)
79.2(2)
81.5(2)
80.5(2)
Ln–Me/CH2 (µ3)–Ln 75.9(1)
87.5(2)
87.9(2)
87.9(2)
82.7(2)
82.8(2)
82.4(2)
55.8 (2)
55.8(2)
56.7(2)
77.6(2)
77.8(2)
78.5(2)
93.2(2)
85.0(2)
87.1(2)
80.0(4)
82.1(3)
76.9(1)
76.0(1)
Ln–Me (µ2)–Ln
N–Ln–Namidinate
Ln–N/C(µ3)–Ln
82.0(2)
81.3(2)
82.8(2)
56.2(1)
56.3(1)
56.5(1)
89.6(1)
90.9(1)
90.4(1)
57.9(2)
57.8(2)
58.1(2)
—
—
—
74.47(11)
82.63(10)
115.9(4)
Conclusions
In summary, a series of new reactivity patterns of mixed
methyl/methylidene rare-earth metal trinuclear complexes
have been established, demonstrating that the selective trans-
formation of CH2 and CH3 groups can be achieved, depending
on the nature of substrates such as benzonitrile, phenyl-
Ln(1)–S(1)–Ln(3)
S(1)–C(2)–S(2)
—
—
—
Table 2 Crystal and data collection parameters of complexes 1c, 2a, 3b, 4a and 5b
1c
2a
3b
4a
5b
Formula
Molecular weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C
112H133Er3N6
C105H136N7Y3
1762.94
Monoclinic
C2/c
59.812(17)
15.628(5)
23.955(7)
106.042(4)
21520(11)
8
C106H137Lu3N6
2020.13
Triclinic
ˉ
P1
18.234(6)
18.459(6)
22.201(7)
81.612(5)
6396(4)
2
1.049
2.333
2056
C109H145N6SiY3
1834.13
Triclinic
ˉ
P1
18.250(6)
18.607(7)
22.153(8)
79.357(5)
10139(7)
2
0.942
1.382
1944
C98H116N6S2Lu3
1967.00
Monoclinic
C2/c
52.952(19)
15.750(6)
28.184(10)
120.002(5)
20356(13)
8
2065.02
Triclinic
ˉ
P1
17.8983(19)
18.311(2)
22.046(3)
75.721(2)
6103.7(12)
2
β (°)
V (Å3)
Z
Dc (g cm−3
)
1.124
2.084
2102
1.088
1.648
7456
1.284
2.970
7928
μ (mm−1
F (000)
)
Temperature (K)
θ range (°)
No. of reflections measured
Data/restraints/parameters
Goodness-of-fit on F2
R1[I > 2σ (I)]
296(2)
0.96 to 25.10
36 623
21 457/46/1066
1.002
0.0566
293(2)
1.35 to 25.05
44 146
18 999/48/1084
0.993
0.0568
293(2)
1.27 to 25.10
26 653
22 202/45/1081
0.991
0.0538
296(2)
1.25 to 25.00
26 976
22 355/62/1081
1.005
0.0658
293(2)
1.37 to 26.00
45 514
19 941/33/1029
0.864
0.0517
wR2
0.1529
0.1055
0.1351
0.1420
0.1081
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Dalton Transactions
acetylene, trimethylsilylacetylene, and CS2, and multinuclear
metal synergetic effects have been observed in these reactions.
Furthermore, the present work indicates that mixed methyl/
methylidene rare-earth metal complexes containing amidinate
coligands are practical and versatile precursors for the prepa-
ration of various trinuclear rare-earth complexes that are other-
wise difficult to access by other ways, by which a series of
novel µ3-1-aza-allyl, alkenyl, alkynyl, and ethene-1,1-dithiolate
complexes have been successfully isolated and fully character-
ized. All these complexes might become an option for methyl-
ation or methylenation reagents in organic or organometallic
chemistry due to their good thermal and structural stability,
and easy reproducibility. The other reactions of complexes pre-
sented in this paper are under investigation.
A. J. Blake and C. Wilson, Angew. Chem., 2003, 115, 6163–
6166, (Angew. Chem. Int. Ed., 2003, 42, 5981–5984);
(c) S. T. Liddle, J. McMaster, J. C. Green and P. L. Arnold,
Chem. Commun., 2008, 1747–1749.
5 (a) M. Zimmermann, J. Takats, G. Kiel, K. W. Törnroos and
R. Anwander, Chem. Commun., 2008, 612–614;
(b) R. Litlabø, M. Zimmermann, K. Saliu, J. Takats,
K. W. Törnroos and R. Anwander, Angew. Chem., 2008, 120,
9702–9706, (Angew. Chem. Int. Ed., 2008, 47, 9560–9564);
(c) A. Venugopal, I. Kamps, D. Bojer, R. J. F. Berger, A. Mix,
A. Willner, B. Neumann, H.-G. Stammler and N. W. Mitzel,
Dalton Trans., 2009, 5755–5765; (d) D. Schädle,
M. Zimmermann, C. M. Mössmer, C. Schädle,
K. W. Törnroos and R. Anwander, Dalton Trans., 2015, 44,
18101–18110.
6 (a) H. M. Dietrich, K. W. Törnroos and R. Anwander, J. Am.
Chem. Soc., 2006, 128, 9298–9299; (b) M. Zimmermann,
D. Rauschmaier, K. Eichele, K. W. Törnroos and
R. Anwander, Chem. Commun., 2010, 46, 5346–5348.
7 (a) J. Hong, L. Zhang, X. Yu, M. Li, Z. Zhang, P. Zheng,
M. Nishiura, Z. Hou and X. Zhou, Chem. – Eur. J., 2011, 17,
2130–2137; (b) W. Zhang, Z. Wang, M. Nishiura, Z. Xi and
Z. Hou, J. Am. Chem. Soc., 2011, 133, 5712–5715; (c) T. Li,
M. Nishiura, J. Cheng, Y. Li and Z. Hou, Chem. – Eur. J.,
2012, 18, 15079–15085; (d) J. Hong, L. Zhang, K. Wang,
Y. Zhang, L. Weng and X. Zhou, Chem. – Eur. J., 2013, 19,
7865–7873; (e) T. Li, M. Nishiura, J. Cheng, W. Zhang, Y. Li
and Z. Hou, Organometallics, 2013, 32, 4142–4148;
(f) K. Wang, G. Luo, J. Hong, X. Zhou, L. Weng, Y. Luo and
L. Zhang, Angew. Chem., 2014, 126, 1071–1074, (Angew.
Chem. Int. Ed., 2014, 53, 1053–1056); (g) J. Zhou, T. Li,
L. Maron, X. Leng and Y. Chen, Organometallics, 2015, 34,
470–476; (h) C. Wang, J. Zhou, X. Zhao, L. Maron, X. Leng
and Y. Chen, Chem. – Eur. J., 2016, 22, 1258–1261.
Acknowledgements
This work was supported by the NSFC, 973 Program
(2012CB821604).
References
1 (a) E. M. Leitao, E. F. van der Eide, P. E. Romero,
W. E. Piers and R. McDonald, J. Am. Chem. Soc., 2010, 132,
2784–2794; (b) A. H. Hoveyda, S. J. Malcolmson, S. J. Meek
and A. R. Zhugralin, Angew. Chem., 2010, 122, 38–49,
(Angew. Chem. Int. Ed., 2010, 49, 34–44); (c) S. Monsaert,
A. Lozano Vila, R. Drozdzak, P. Van Der Voort and
F. Verpoort, Chem. Soc. Rev., 2009, 38, 3360–3372;
(d) J. Scottt and D. J. Mindiola, Dalton Trans., 2009, 8463–
8472; (e) R. H. Grubbs, Adv. Synth. Catal., 2007, 349, 34–40;
(f) R. R. Schrock, Adv. Synth. Catal., 2007, 349, 41–50.
2 (a) J. R. Stille and R. H. Grubbs, J. Am. Chem. Soc., 1986,
108, 855–856; (b) N. A. Petasis and E. I. Bzowej, J. Am.
Chem. Soc., 1990, 112, 6392–6394; (c) N. A. Petasis and
Y.-N. Hu, J. Org. Chem., 1997, 62, 782–783;
(d) R. R. Schrock, Chem. Rev., 2009, 109, 3211–3226;
(e) P. S. Kumar, K. Wurst and M. R. Buchmeiser, J. Am.
Chem. Soc., 2009, 131, 387–395; (f) M. M. Flook,
L. C. H. Gerber, G. T. Debelouchina and R. R. Schrock,
Macromolecules, 2010, 43, 7515–7522.
3 (a) G. R. Giesbrecht and J. C. Gordon, Dalton Trans., 2004,
2387–2393; (b) P. L. Arnold and S. T. Liddle, Chem.
Commun., 2006, 3959–3971; (c) J. Scott, H. Fan,
B. F. Wicker, A. R. Fout, M.-H. Baik and D. J. Mindiola,
8 (a) Z. Hou, M. Nishiura and T. Shima, Eur. J. Inorg. Chem.,
2007, 2535–2545; (b) M. Ohashi, M. Konkol, I. D. Rosal,
R. Poteau, L. Maron and J. Okuda, J. Am. Chem. Soc., 2008,
130, 6920–6921; (c) J. Cheng, M. J. Ferguson and J. Takats,
J. Am. Chem. Soc., 2010, 132, 2–3; (d) J. Cheng, T. Shima
and Z. Hou, Angew. Chem., 2011, 123, 1897–1900, (Angew.
Chem. Int. Ed., 2011, 50, 1857–1860); (e) A. Venugopal,
W. Fegler, T. P. Spaniol, L. Maron and J. Okuda, J. Am.
Chem. Soc., 2011, 133, 17574–17577; (f) T. Shima, Y. Luo,
T. Stewart, R. Bau, G. J. McIntyre, S. A. Mason and Z. Hou,
Nat. Chem., 2011, 3, 814–820.
9 W. J. Evans, M. A. Ansari and J. W. Ziller, Inorg. Chem.,
1996, 35, 5435–5444.
J. Am. Chem. Soc., 2008, 130, 14438–14439; (d) M. Fustier, 10 J. Rami, M. Jamie, L. Polly and E. Moris, Organometallics,
X. F. Le Goff, P. Le Floch and N. Mézailles, J. Am. Chem. 2015, 34, 4039–4050, and see the references therein.
Soc., 2010, 132, 13108–13110; (e) D. P. Mills, L. Soutar, 11 (a) M. Nishiura, Z. Hou, Y. Wakatsuki, T. Yamaki and
W. Lewis, A. J. Blake and S. T. Liddle, J. Am. Chem. Soc.,
2010, 132, 14379–14381; (f) J. Kratsch and P. Roesky,
Angew. Chem., 2014, 126, 384–391, (Angew. Chem. Int. Ed.,
2014, 53, 376–383), and see the references therein.
T. Miyamoto, J. Am. Chem. Soc., 2003, 125, 1184–1185;
(b) W. Zhang, M. Nishiura and Z. Hou, J. Am. Chem. Soc.,
2005, 127, 16788–16789; (c) W. Zhang and Z. Hou, Org.
Biomol. Chem., 2008, 6, 1720–1730.
4 (a) K. Aparna, M. Ferguson and R. G. Cavell, J. Am. Chem. 12 W. J. Evans, T.M. Champagne and J. W. Ziller, J. Am. Chem.
Soc., 2000, 122, 726–727; (b) P. L. Arnold, S. A. Mungur, Soc., 2006, 128, 14270–14271.
Dalton Trans.
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13 (a) M. X.-W. Jiang, M. Rawat and W. D. Wulff, J. Am. Chem.
Soc., 2004, 126, 5970–5971; (b) T. B. Wen, W. Y. Hung,
D. P. Mills and A. Stasch, Dalton Trans., 2010, 39, 1877–
1882.
H. H. Y. Sung, I. D. Williams and G. Jia, J. Am. Chem. Soc., 16 F. H. Allen, O. Kennard, D. G. Watson, L. Brammer and
2005, 127, 2856–2857; (c) J. Barluenga, P. García-García, A. G. Orpen, J. Chem. Soc., Perkin Trans. 2, 1987, S1–S19.
M. A. Fernández-Rodríguez, C. Rocaboy, E. Aguilar, 17 Y. R. Li, C. F. Pi, J. Zhang, X. G. Zhou, Z. X. Chen and
F. Andina and I. Merino, Chem. – Eur. J., 2007, 13, 9115– L. H. Weng, Organometallics, 2005, 24, 1982–1988.
9126; (d) S. Duan, D. K. Sinha-Mahapatra and 18 Y. Zhao and D. G. Truhlar, J. Phys. Chem., 2006, 110, 5121–
J. W. Herndon, Org. Lett., 2008, 8, 1541–1544; 5129.
(e) J. Barluenga, A. Gómez, J. Santamaría and M. Tomás, 19 Y. Zhao and D. G. Truhlar, Theor. Chem. Acc., 2008, 120,
Angew. Chem., 2010, 122, 1328–1330, (Angew. Chem. Int. Ed., 215–241.
2010, 49, 1306–1308); (f) R. A. Fernandes and S. V. Mulay, 20 (a) M. Dolg, U. Wedig, H. Stoll and H. Preuss, J. Chem.
J. Org. Chem., 2010, 75, 7029–7032.
14 (a) M. T. Whited and R. H. Grubbs, Organometallics, 2009,
Phys., 1987, 86, 866–872; (b) M. Dolg, H. Stoll and
H. Preuss, Theor. Chem. Acc., 1993, 85, 441–450.
28, 161–166; (b) A. Ariafard, N. J. Brookes, R. Stranger and 21 (a) A. D. McLean and G. S. Chandler, J. Chem. Phys., 1980,
B. F. Yates, J. Am. Chem. Soc., 2008, 130, 11928;
(c) K. K. Pandey, Coord. Chem. Rev., 1995, 140, 37–114;
72, 5639–5648; (b) R. Krishnan, J. S. Binkley, R. Seeger and
J. A. Pople, J. Chem. Phys., 1980, 72, 650–654.
(d) A. E. Guiducci, C. L. Boyd and P. Mountford, Organo- 22 M. J. Frisch, et al., Gaussian 09, Revision A.02, Gaussian,
metallics, 2006, 25, 1167–1187; (e) T. Gandhi, M. Nethaji Inc., Wallingford CT, 2009.
and B. R. Jagirdar, Inorg. Chem., 2003, 42, 4798–4800; 23 R. W. Stotz and G. A. Melson, Inorg. Chem., 1972, 11, 1720–
(f) D. Sellmann, P. Lechner, F. Knoch and M. Moll, J. Am. 1721.
Chem. Soc., 1992, 114, 922–930; (g) C. Bianchini, 24 (a) L. X. Zhang, M. Nishiura, M. Yuki, Y. Luo and
C. A. Ghilardi, A. Meli, S. Midollini and A. Orlandini,
J. Chem. Soc., Chem. Commun., 1983, 545–546.
15 (a) K. H. den Haan, G. A. Luinstra, A. Meetsma and
Z. M. Hou, Angew. Chem., 2008, 120, 2682–2685, (Angew.
Chem. Int. Ed., 2008, 47, 2642–2645); (b) M. Nishiura and
Z. Hou, Nat. Chem., 2010, 2, 257–268.
J. H. Teuben, Organometallics, 1987, 6, 1509–1515; 25 SAINTPlus Data Reduction and Correction Program v. 6.02 a,
(b) J. R. van den Hende, P. B. Hitchcock and M. F. Lappert, Bruker AXS, Madison, WI, 2000.
J. Chem. Soc., Dalton Trans., 1995, 2251–2258; 26 G. M. Heldrick, A. ADABS, Program for Empirical Absorption
(c) W. J. Evans, C. A. Seibel, J. W. Ziller and R. J. Doedens,
Organometallics, 1998, 17, 2103–2112; (d) S. Wang, Q. Yang,
Correction, University of Göttingen, Göttingen, Germany,
1998.
T. C. W. Mak and Z. Xie, Organometallics, 2000, 19, 334– 27 G. M. Sheldrick, SHELXL-97, Program for the Refinement of
343; (e) H. Li, Y. Yao, Q. Shen and L. Weng, Organometal-
lics, 2002, 21, 2529–2532; (f) D. Heitmann, C. Jones,
Crystal Structures, University of Göttingen, Göttingen,
Germany, 1997.
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