Thorium oxo and sulfido metallocenes: Synthesis, structure, reactivity, and computational studies

Article abstract of DOI:10.1021/ja205280k

The synthesis, structure, and reactivity of thorium oxo and sulfido metallocenes have been comprehensively studied. Heating of an equimolar mixture of the dimethyl metallocene [η⁵-1,2,4-(Me₃C) ₃C₅H₂]₂ThMe₂ (2) and the bis-amide metallocene [η⁵-1,2,4-(Me₃C) ₃C₅H₂]₂Th(NH-p-tolyl)₂ (3) in refluxing toluene results in the base-free imido thorium metallocene, [η⁵-1,2,4-(Me₃C)₃C₅H ₂]₂Th=N(p-tolyl) (4), which is a useful precursor for the preparation of oxo and sulfido thorium metallocenes [η⁵-1,2,4- (Me₃C)₃C₅H₂]₂Th=E (E = O (5) and S (15)) by cycloaddition-elimination reaction with Ph₂C=E (E = O, S) or CS₂. The oxo metallocene 5 acts as a nucleophile toward alkylsilyl halides, while sulfido metallocene 15 does not. The oxo metallocene 5 and sulfido metallocene 15 undergo a [2 + 2] cycloaddition reaction with Ph₂CO, CS₂, or Ph₂CS, but they show no reactivity with alkynes. Density functional theory (DFT) studies provide insights into the subtle interplay between steric and electronic effects and rationalize the experimentally observed reactivity patterns. A comparison between Th, U, and group 4 elements shows that Th⁴⁺ behaves more like an actinide than a transition metal.

Full text of DOI:10.1021/ja205280k

ARTICLE
pubs.acs.org/JACS
Thorium Oxo and Sulfido Metallocenes: Synthesis, Structure,
Reactivity, and Computational Studies
Wenshan Ren,† Guofu Zi,*,† De-Cai Fang,*,† and Marc D. Walter*,‡
†Department of Chemistry, Beijing Normal University, Beijing 100875, China
‡Institut f€ur Anorganische und Analytische Chemie, Technische Universit€at Braunschweig, Hagenring 30, 38106 Braunschweig,
Germany
S Supporting Information
b
ABSTRACT: The synthesis, structure, and reactivity of thor-
ium oxo and sulfido metallocenes have been comprehensively
studied. Heating ofanequimolarmixtureofthedimethyl metallo-
cene [η5-1,2,4-(Me3C)3C5H2]2ThMe2 (2) and the bis-amide
metallocene [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)2 (3) in
refluxing toluene results in the base-free imido thorium metallo-
cene, [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4), which is a
useful precursor for the preparation of oxo and sulfido thorium
metallocenes [η5-1,2,4-(Me3C)3C5H2]2ThdE (E = O (5) and
S (15)) by cycloadditionꢀelimination reaction with Ph2CdE (E = O, S) or CS2. The oxo metallocene 5 acts as a nucleophile toward
alkylsilyl halides, while sulfido metallocene 15 does not. The oxo metallocene 5 and sulfido metallocene 15 undergo a [2 + 2]
cycloaddition reaction with Ph2CO, CS2, or Ph2CS, but they show no reactivity with alkynes. Density functional theory (DFT)
studies provide insights into the subtle interplay between steric and electronic effects and rationalize the experimentally observed
reactivity patterns. A comparison between Th, U, and group 4 elements shows that Th4+ behaves more like an actinide than a
transition metal.
example of a terminal actinide sulfido complex, uranium sulfido
complex [Na(18-crown-6)][(η5-Me5C5)2U(S)(SCMe3)], has
been structurally authenticated.4 Thus, the development of novel
actinide oxo and sulfido complexes remains an interesting and
challenging synthetic target. In the course of our studies of
actinide complexes, we are interested in thorium metallocenes
with ThdE (O and S) double bonds. This research is motivated
by the fact that ThO2 has been used as a catalyst for various
chemical transformations. While it can serve in some reactions as
a support for other catalysts, a catalytic activity of ThO2 itself
cannot be excluded in these cases. Most notable is the activity of
ThO2 in FischerꢀTropsch synthesis, hydrogenation and dehy-
drogenation, and oxidation reactions.7 In addition, thorium has a
ground-state electron configuration of 7s26d2, which suggests
that it might exhibit reactivity similar to group 4 elements, such as
Ti, Zr, and Hf, for which the corresponding metallocenes with
MdE (E = O and S) have been prepared.8 This comparison also
addresses the question whether the Th4+ should be considered as
an actinide or as a transition metal and whether f-orbitals con-
tribute to the bonding in thorium organometallics.8ꢀ10 Although
thorium oxo and sulfido metallocenes have not been described so
far, two examples of oxo and one example of sulfido uranium(IV)
metallocenes have been structurally authenticated.3d,e,4 It has
1. INTRODUCTION
The organoactinide complexes containing terminal metalꢀ
ligand multiple bonds have received widespread attention over
the past two decades due to their unique structural properties and
their potential applications in group transfer and catalysis.1
Among these, oxo and sulfido organoactinide complexes are of
particular interest,1ꢀ4 because these functionalities are ubiqui-
tous in actinide chemistry, as shown by the prevalence of binary
oxides and sulfides in the solid state.5 In this context, well-defined
molecular structures will advance our understanding of the
bonding and reactivity of AndO and AndS functional groups
and help to uncover novel transformations that may be used in
industrial environments. For example, the interaction between
solid U3O8 and chlorocarbons results in complete destruction of
the latter to COx and HCl.6 This unusual and potentially useful
reaction probably occurs at UꢀO functional groups on the sur-
face UꢀO. While many oxo organouranium complexes have been
prepared, only a few of them exhibit significant reactivity, and
many studies have focused on their structural characterizations.2,3
However, the reaction of alkylhalides with the model complex
[η5-1,2,4-(Me3C)3C5H2]2UdO provides information on the
nature of the UdO bond on a molecular level.3e In contrast to
oxo organouranium chemistry, to the best of our knowledge, no
examples of other actinide metal oxo organometallic complexes
have been reported. Furthermore, only a few actinide complexes
contain purely inorganic chalcogenide ligands and only one
Received: June 8, 2011
Published: July 27, 2011
r
2011 American Chemical Society
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Scheme 1
been noted that uranium(IV) oxo or sulfido metallocene forma-
tion is especially sensitive to steric effects imposed by the
cyclopentadienyl ligand. The formation of dimers with bridging
oxo or sulfidogroupsisoftenobserveddueto thepotent basicity of
these groups.3e,4 For example, the ligand 1,3-(Me3C)2C5H3
yields the oxo-dimer {[η5-1,3-(Me3C)2C5H3]2U}2(μ-O)2,11 while
the sterically very encumbered cyclopentadienyl ligand 1,2,4-
(Me3C)3C5H2 can efficiently stabilize the base-free uranium oxo
metallocene [η5-1,2,4-(Me3C)3C5H2]2UdO (monomeric in
gas phase).3e Encouraged by the attractive feature of this bulky
ligand, we have recently started exploring the 1,2,4-(Me3C)3C5H2
ligand in thorium chemistry. We have found that the 1,2,4-
(Me3C)3C5H2 ligand stabilizes the base-free thorium imido
metallocene, [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4). Herein,
we report the synthesis of the imido metallocene 4, its use in the
preparation of oxo and sulfido metallocenes, [η5-1,2,4-(Me3C)3-
C5H2]2ThdE (E = O (5) and S (15)), and their reactivity. In
addition, the differences and similarities between the uranium-
(IV), thorium(IV), and group 4 metallocenes will be addressed in
this Article.
Scheme 2
2.2. Thorium Oxo Metallocenes. It has been shown that the
reaction of uranium p-tolylimido metallocene, [η5-1,2,4-(Me3C)3-
C5H2]2UdN(p-tolyl), with 1 or 2 equiv of Ph2CO gives the oxo
metallocene, [η5-1,2,4-(Me3C)3C5H2]2UO, and its adduct [η5-
1,2,4-(Me3C)3C5H2]2UO(OCPh2).3e The addition of pyridine,
4-Me2NC5H4N (dmap), or THF to this solution yields the stable
monomeric adducts, [η5-1,2,4-(Me3C)3C5H2]2UO(py) and
[η5-1,2,4-(Me3C)3C5H2]2UO(dmap), which can be isolated,
but no THF adduct [η5-1,2,4-(Me3C)3C5H2]2UO(THF) is
formed.3e In contrast, under similar reaction conditions, treat-
ment of 4 with 1 or 2 equiv of Ph2CO results in the isolation of
the metallocenes, {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6)
and [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-O)2(CPh2)] (7), respec-
tively. In both cases, the oxo metallocene [η5-1,2,4-(Me3C)3-
C5H2]2ThO (5) has undergone an irreversible nucleophilic add-
ition (Scheme 2). However, when the reaction of 4 with 1 equiv
of Ph2CO is carried out in C6D6 solution in the presence of
THF, pyridine, or 4-Me2NC5H4N, the corresponding adducts,
[η5-1,2,4-(Me3C)3C5H2]2ThO(s) (s = THF (8), py (9), dmap
(10)), are formed (Scheme 3). The adducts 8 and 9 are stable
2. RESULTS AND DISCUSSION
2.1. Imido Metallocene [η5-1,2,4-(Me3C)3C5H2]2ThdN-
(p-tolyl). Treatment of ThCl4(tmeda)2 with 2 equiv of [1,2,4-
(Me3C)3C5H2]K in boiling toluene gives the dichloro metallo-
cene, [η5-1,2,4-(Me3C)3C5H2]2ThCl2 (1), in 85% yield. Salt meta-
thesis between 1 and 2 equiv of MeLi in diethyl ether affords the
dimethyl metallocene, [η5-1,2,4-(Me3C)3C5H2]2ThMe2 (2), in
79% yield. Subsequent reaction of 2 with 2 equiv of p-toluidine in
toluene gives the bis-amido metallocene, [η5-1,2,4-(Me3C)3-
C5H2]2Th(NH-p-tolyl)2 (3), in 90% yield. Finally, heating of
an equimolar mixture of 2 and 3 in refluxing toluene gives the
desired base-free imido thorium metallocene, [η5-1,2,4-(Me3C)3-
C5H2]2ThdN(p-tolyl) (4), in 85% yield (Scheme 1). Imido 4 is
soluble in and readily recrystallized from toluene solution, but
1
only slightly soluble in n-hexane. The H and 13C{1H} NMR
spectra indicate that it is symmetrical on the NMR time scale,
1
1
which is consistent with its C2v-symmetric structure. The H
at ambient temperature in C6D6 solution as monitored by H
NMR spectrum of 3 shows that the singlet of the NH groups at δ
5.07 ppm disappears upon treatment of 3 with 2, and the ratio of
the Cp-ligand and p-tolyl group changes to 2:1. In addition, the
infrared spectrum shows the disappearance of the characteristic
NꢀH absorption at 3254 cmꢀ1 and therefore supports the
formation of 4.
NMR spectroscopy, but the dimeric μ-oxo metallocene 6 is
formed when the solvent is removed or when the solution is
heated. In contrast, the adduct [η5-1,2,4-(Me3C)3C5H2]2ThO-
(dmap) (10) may be isolated at room temperature, but it
degrades to 6 in solution at 65 °C. These observations show
that the stability of actinide oxo metallocenes is very sensitive to
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Scheme 3
Figure 1. Molecular structure of 10 (thermal ellipsoids drawn at the
35% probability level).
the thorium derivative 5 and its adducts 8ꢀ10 do not react with
aryl and alkyl halides. This implies that the ThdO bond is less
active than the UdO bond. A similar conclusion can be derived
from the fact that the heterogeneous reaction of solid U3O8
with chlorocarbons is fast at moderate temperature (<400 °C),6
while the reaction of ThO2 with CCl4 requires high temperatures
of 450ꢀ500 °C.14
the size of the metal ion12 and the electron-donating capability of
the coordinated Lewis base.3d,e
The uranium oxo metallocene [η5-1,2,4-(Me3C)3C5H2]2UO
and its adduct, [η5-1,2,4-(Me3C)3C5H2]2UO(py), reacted im-
mediately upon mixing with an excess of alkylsilyl halides to give
the addition products at room temperature, but no cycloaddition
behavior was observed with alkynes.3e The thorium oxo deriva-
tive [η5-1,2,4-(Me3C)3C5H2]2ThO (5) and its adducts 8ꢀ10
behave similarly. Direct treatment of either 1 or 2 equiv of
benzophenone with a mixture of 4 and Me3SiX in toluene forms
rapidly the metallocenes, [η5-1,2,4-(Me3C)3C5H2]2Th(OSiMe3)-
(X) (X = Cl (11), CN (12)) (Scheme 3). Treatment of C6D6
solutions of 8, 9, or 10 with an excess of Me3SiX also cleanly
yields the metallocenes 11 and 12 (Scheme 3). When heated at
65 °C, 11 can further react with an excess of Me3SiCl to give 1.
However, the dimeric oxo metallocene 6 exhibits no reaction
with an excess of Me3SiX in C6D6 even when heated at 65 °C for
3 days, while 7 reacts rapidly with an excess of Me3SiCl to form 1.
This indicates that the formation of 6 and 7 is irreversible and the
active species in above reactions is the monomeric oxo metallo-
cene 5. However, in contrast to (η5-C5Me5)2TiO(py),8a no
reaction occurs when a C6D6 solution of 8 or 9 is treated with
an excess of alkynes R0CtCR0 (R0 = Me, Ph, Me3Si) at room
temperature, and when the temperature is increased to 65 °C
dimer 6 is formed in quantitative yield, due to the more polarized
nature of the actinide oxo bond.13 When 4 is added directly to a
C6D6 solution of benzophenone and alkynes R0CtCR0 (R0 =
Me, Ph, Me3Si), 6 is formed in quantitative yield, indicating
that the oxo 5 cannot be trapped by alkynes in contrast to
(η5-C5Me5)2ZrO.8b This is again consistent with the more polarized
An+ꢀOꢀ bond.13 When a terminal alkyne PhCtCH is used, proton
transfer is observed accompanied by the formation of free ligand,
(Me3C)3C5H3. In contrast to [η5-1,2,4-(Me3C)3C5H2]2UdO,3e
An ORTEP diagram of [η5-1,2,4-(Me3C)3C5H2]2ThO-
(dmap) (10) is shown in Figure 1. The orientation of the Cp-
rings is nearly staggered, and the dmap ligand and oxygen atom
lie in the open wedge of the bent metallocene. The dmap ligand is
nearly planar with the dihedral angle defined by intersection of
the planar pyridine ring and the plane NMe2 group as 14°, with
the planar pyridine ring twisted out of the plane defined by the
ThꢀNꢀO atoms. Thus, the molecule has no symmetry in the
solid state. The oxo adduct 10 represents, to the best of our
knowledge, the first structurally characterized terminal oxo tho-
rium metallocene. The ThꢀO distance is short with 1.929(4) Å,
supporting the formation of a terminal oxoꢀmetal bond,15 al-
though it is longer than that found in thorium oxide, ThO (gas
phase) (1.84 Å).16 Furthermore, it is longer than the UdO
bonds found in (η5-C5Me5)2U(O)(O-2,6-i-Pr2C6H3) (1.859(6)
Å),3b (η5-C5Me5)2U(O)(N-2,6-i-Pr2C6H3) (1.844(4) Å),3c
(η5-C5Me5)2U(O)[C(NMeCMe)2] (1.917(6) Å),3d [η5-1,2,4-
(Me3C)3C5H2]2UO(dmap) (1.860(3) Å),3e and the ZrdO
bond found in (η5-Me4C5Et)2ZrO(py) (1.804(4) Å),8c but
shorter than the ThdN bond found in (η5-C5Me5)2ThdN-
(2,6-Me2C6H3)(thf) (2.045(8) Å).17 The ThꢀN(dmap) distance
is 2.587(5) Å, which is shorter than those found in Th(O-2,6-
Me2C6H3)4(py)2 (2.662(8) and 2.696(8) Å),18 Th(OCMe3)4-
(py)2 (2.752(7) Å),19 and longer than the UꢀN bond found in
[η5-1,2,4-(Me3C)3C5H2]2UO(dmap) (2.535(4) Å),3e and ZrꢀN
bond found in (η5-Me4C5Et)2ZrO(py) (2.363(5) Å).8c
The solid-state crystal structures of [η5-1,2,4-(Me3C)3C5H2]2Th-
(OSiMe3)(Cl) (11) and [η5-1,2,4-(Me3C)3C5H2]2Th(OSiMe3)-
(CN) (12) have been determined, and the ORTEP diagram for
12 is shown in Figure 2, whereas the ORTEP presentation for 11
is given in the Supporting Information. In each molecule, the Th4+
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ion coordinated in a distorted-tetrahedral geometry by two η5-
bound Cp-rings and by one σ-bound oxygen atom and by one σ-
bound chlorine atom (for 11) or one nitrogen atom (for 12).
The average ThꢀC(ring) distance is 2.861(3) Å for 11 and
2.849(4) Å for 12, respectively (Table 1). The cyclopentadienyl
rings in these two metallocenes adopt a nearly eclipsed con-
formation, with the Me3C-groups on each ring at the back of the
wedge located as far from each other as possible. This orientation
sets the disposition of the other four Me3C-groups such that two
of them pointing toward the open wedge are nearly eclipsed. The
ThꢀOꢀSi angle is 166.1(2)° for 11, which is close to that
(168.3(2)°) in 12, but it is larger than the angle of UꢀOꢀSi
found in [η5-1,2,4-(Me3C)3C5H2]2U(OSiMe3)(CN) (160.6(3)°).3e
The ThꢀNꢀC angle is 158.2(4)°, which is smaller than the
angle of UꢀNꢀC found in [η5-1,2,4-(Me3C)3C5H2]2U-
(OSiMe3)(CN) (164.5(7)°).3e A nonlinear ThꢀOꢀSi angle
is common, while a ThꢀNꢀC angle is not. A possible reason
may be traced to the steric strain on the OSiMe3 and CN
groups imposed by the methyl groups of the CMe3 adjacent
to them.
yield the metallacycles, [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)-
C(S)ꢀS] (13) and [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C-
(NPh)ꢀS] (14), respectively (Scheme 4). In C6D6 solution,
complex 14 is stable at 160 °C for 3 days, whereas 13 degrades
irreversibly when heated at 65 °C overnight to the dimeric
thorium μ-sulfido metallocene, {[η5-1,2,4-(Me3C)3C5H2]2Th}2-
(μ-S)2 (16). Heating a benzene solution of 13 at 65 °C in the
presence of an excess of CS2 forms the cluster, {[η5-1,2,4-
(Me3C)3C5H2]2Th(S)[(μ-S)2C]}6 (17) (Scheme 4). Complex
4 reacts irreversibly with 2 equiv of Ph2CS at room temperature
to give the complex [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CPh2]
(18) (Scheme 2). These observations suggest that the mono-
meric thorium sulfido metallocene [η5-1,2,4-(Me3C)3C5H2]2-
ThS (15) is unstable and undergoes an irreversible dimerization
or nucleophilic addition resembling that of the thorium oxo 5. In
contrast, the monomeric zirconium sulfido complex (η5-tBuC5H4)2-
ZrS shows a monomerꢀdimer equilibrium in solution,8e
Scheme 4
2.3. Thorium Sulfido Metallocenes. Thorium p-tolylimido
metallocene 4 reacts rapidly with 1 equiv of CS2 or PhNCS to
Figure 2. Molecular structure of 12 (thermal ellipsoids drawn at the
35% probability level).
Table 1. Selected Distances (Å) and Angles (deg) for Compounds 6, 7, 10ꢀ14, 16, 17, and 19a
C(Cp)ꢀTh
Cp(cent)ꢀTh
XꢀThꢀX (ave) or
XꢀThꢀY
compound
(ave)
C(Cp)ꢀTh (range)
(ave)
ThꢀX (ave)
Cp(cent)ꢀThꢀCp(cent)
6
2.893(9) 2.776(8)ꢀ3.117(9)
2.898(4) 2.785(4)ꢀ3.001(4)
2.936(6) 2.896(6)ꢀ2.991(5)
2.861(3) 2.791(3)ꢀ2.916(3)
2.849(4) 2.774(4)ꢀ2.925(4)
2.838(7) 2.780(7)ꢀ2.935(7)
2.853(4) 2.793(4)ꢀ2.955(4)
2.893(9) 2.761(8)ꢀ3.098(9)
2.875(8) 2.777(8)ꢀ2.997(7)
2.731(9)
2.615(4)
2.676(6)
2.594(3)
2.580(4)
2.571(7)
2.584(4)
2.659(9)
2.609(8)
ThꢀO 2.179(6)
118.6(8), 119.3(8)
133.4(4)
71.1(2)
62.4(2)
90.1(2)
91.1(1)
90.3(1)
62.3(2)
63.0(1)
76.8(1)
61.4(1)b
55.9(2)c
7
ThꢀO 2.202(3), ThꢀC 2.741(6)
ThꢀO 1.929(4), ThꢀN 2.587(5)
ThꢀO 2.143(3), ThꢀCl 2.647(1)
ThꢀO 2.132(3), ThꢀN 2.454(4)
10
11
12
13
14
16
17
19
142.6(6)
133.9(4)
136.1(4)
ThꢀS 2.704(2), ThꢀN 2.347(6), ThꢀC 2.983(9) 141.0(2)
ThꢀS 2.709(1), ThꢀN 2.328(3), ThꢀC 2.989(3) 140.4(3)
ThꢀS 2.709(2)
ThꢀS 2.852(2), ThꢀC 3.338(8)
119.4(1), 119.4(1)
140.2(1)
2.879(10) 2.783(9)ꢀ3.053(10) 2.615(10) ThꢀS 2.890(3), ThꢀN 2.587(8), ThꢀC 3.131(9) 134.6(3)
a Cp = cyclopentadienyl ring. b The angle of S(1)ꢀTh(1)ꢀS(2). c The angle of S(1)ꢀTh(1)ꢀN(1).
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Figure 4. Molecular structure of 6 (thermal ellipsoids drawn at the 35%
probability level).
Figure 3. Molecular structure of 13 (thermal ellipsoids drawn at the
35% probability level).
suggesting that the Th4+ behaves more like an actinide than a
transition metal.13 Upon addition of 1 equiv of Ph2CS to 4 in
1
C6D6, the H NMR spectrum of the crude reaction mixture
shows resonances due to p-tolylNdCPh2, new resonances
attributable to [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CPh2] (18),
and unreacted 4. The addition of 1 equiv of Ph2CS to a mixture of
4 and Me3SiCl or 4-dimethylaminopyridine (dmap) in C6D6
rapidly forms 18 and p-tolylNdCPh2 with 50% conversion
(based on 4). Interestingly, the Lewis base dmap cannot stabilize
the sulfido 15 in contrast to the oxo derivative 5, pointing to the
subtle balance between steric demand of the heteroatom anion
and the electron donating capability of the Lewis base governing
the reactivity and stability of the ThdX functionality. Similar to
5, no [2 + 2] cycloaddition products [η5-1,2,4-(Me3C)3C5H2]2-
Th[SC(R0)dC(R0)] are obtained when 13 is heated with an
excess of alkynes R0CtCR0 (R0 = Me, Ph, Me3Si) at 65 °C in
C6D6 solution; instead, the μ-sulfido dimer 16 may be isolated,
indicating that sulfido 15 cannot be trapped by alkynes in con-
trast to (η5-C5Me5)2TiS(py)8f and (η5-C5Me5)2ZrS,8b again,
presumably due to the more polarized nature of the actinide
sulfido bond.13 Under similar reaction conditions, treatment of
13 or 14 with an excess of Me3SiCl at 65 °C in a benzene solution
does not give the chloride complex [η5-1,2,4-(Me3C)3C5H2]2-
Th(SSiMe3)(Cl); instead, [η5-1,2,4-(Me3C)3C5H2]2Th[N-
(p-tolyl)C(SSiMe3)ꢀS](Cl) (19) and [η5-1,2,4-(Me3C)3C5H2]2-
Th[N(p-tolyl)C{N(Ph)(SiMe3)}ꢀS](Cl) (20) have been isolated
(Scheme 4).
Figure 5. Molecular structure of 7 (thermal ellipsoids drawn at the 35%
probability level).
ThꢀC(ring) distance of 2.838(7) Å for 13 and 2.853(4) Å for 14,
respectively (Table 1). The orientation of the cyclopentadienyl
rings is nearly eclipsed. The structural parameters indicate that
there is some charge delocalization over the N(1)ꢀC(42)ꢀS(1)
moiety. The Cp(cent)ꢀThꢀCp(cent) angle is 141.0(2)° for 13,
close to that (140.4(3)°) found in 14. The ThꢀS distances in 13
and 14 are very similar at 2.704(2) and 2.709(1) Å, respectively.
This is also reflected in the ThꢀN distances of 2.347(6) Å and
2.328(3) Å, respectively (Table 1).
The solid-state crystal structures of {[η5-1,2,4-(Me3C)3-
C5H2]2Th}2(μ-O)2 (6), [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-O)2-
(CPh2)] (7), and {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-S)2 (16)
have been determined, and the ORTEP diagrams for 6 and 7 are
shown in Figures 4 and 5, whereas the ORTEP presentation
for 16 is given in the Supporting Information. The average
ThꢀC(ring) distances are virtually identical at 2.893(9),
2.898(4), and 2.893(9) Å for 6, 7, and 16, respectively
The solid-state crystal structures of 13 and 14 have been deter-
mined, and the ORTEP diagram for 13 is shown in Figure 3,
whereas the ORTEP presentation for 14 is given in the Support-
ing Information. In each molecule, the Th4+ ion is η5-bond to
two Cp-rings and σ-bound to one nitrogen atom and one sulfur
atom from the group [N(p-tolyl)C(S)ꢀS] or [N(p-tolyl)C-
(NPh)ꢀS] in a distorted-tetrahedral geometry with an average
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(Table 1). In each fragment of [η5-1,2,4-(Me3C)3C5H2]2Th, the
cyclopentadienyl rings adopt a nearly staggered conformation
and the Me3C-groups at the back of the wedge are minimizing
the steric repulsion, and the other four Me3C-groups are oriented
to the left and right side of the open wedge. The Cp-
(cent)ꢀThꢀCp(cent) angles are 118.6(8)° and 119.3(8)° for
6, which are close to those (119.4(1)° and 119.4(1)°) found in
16, but smaller than that (133.4(4)°) found in 7 (Table 1). The
two Th4+ ions are separated by 3.546(1) Å for 6, which is longer
than the UꢀU distance in {[η5-1,3-(Me3Si)2C5H3]2U}2(μ-O)2
(3.393(1) Å),11 consistent with the larger Th4+ ionic
radius.12 In 16, the ThꢀTh distance is 4.246(3) Å, which
can be compared to the UꢀU distance of 3.891(1) Å in
[Na(DME)3]2[{((AdArO)3N)U}2(μ-S)2] ((AdArO)3N3ꢀ = tri-
anion of tris(2-hydroxy-3-adamantyl-5-methylbenzyl)amine),20
presumably due to the larger Th4+ ion in combination with the
sterically more demanding [η5-1,2,4-(Me3C)3C5H2]ꢀ ligand.
The average ThꢀO distance is 2.179(6) Å for 6, and 2.202(3) Å
for 7, which are longer than the ThdO bond (1.929(4) Å) found
in 10, but are shorter than that (2.421 Å) found in the solid-state
structure of thorium dioxide, ThO2.21 In 16, the average ThꢀS
distance is 2.709(2) Å, which is shorter than that found in the
organothorium complex (η5-C5Me5)2ThS5 (2.902(4) Å),22 and
those found in the solid-state thorium sulfides, ThS (2.84 Å),23
Th2S3 (2.90 Å),24 and ThS2 (2.95 Å).25
The single-crystal X-ray diffraction analysis of 17 establishes a
hexanuclear cluster {[η5-1,2,4-(Me3C)3C5H2]2Th(S)[(μ-S)2C]}6
(Figure 6) with six benzene solvate molecules in the crystal lattice.
Each [η5-1,2,4-(Me3C)3C5H2]2Th fragment is η3-coordinated to
one CS32ꢀ fragment and σ-bound to another CS32ꢀ fragment; thus,
self-assembly of six {[η5-1,2,4-(Me3C)3C5H2]2Th}2+ cations and
2ꢀ
six CS3 anions results in the formation of a hexameric macro-
ring.26 The coordination environment in {[η5-1,2,4-(Me3C)3-
C5H2]2Th(S)[(μ-S)2C]} can be described as a distorted trigonal-
bipyramid (Figure 6) with an average ThꢀC(ring) distance of
2.875(8) Å, and a Cp(cent)ꢀThꢀCp(cent) angle of 140.2(1)°.
The orientation of the cyclopentadienyl rings is nearly eclipsed as
previously observed in other complexes. The small differences in the
CꢀS distances (0.003, 0.006, and 0.009 Å) suggest that the negative
charge is delocalized over the CS32ꢀ fragment. The average ThꢀS
distance of 2.852(2) Å is comparable to those found in 16 (2.709(2)
Å), (η5-C5Me5)2ThS5 (2.902(4) Å),22 ThS (2.84 Å),23 Th2S3 (2.90
Å),24 and ThS2 (2.95 Å).25
Figure 6. (a) Molecular structure of 17 (tert-butyl group omitted for
clarity, thermal ellipsoids drawn at the 35% probability level). (b)
Molecular building block of the hexameric cluster 17.
The single-crystal X-ray diffraction analysis of [η5-1,2,4-
(Me3C)3C5H2]2Th[N(p-tolyl)C(SSiMe3)ꢀS](Cl) (19) reveals
two independent molecules in the asymmetric unit. Each mole-
cule possesses a distorted trigonal-bipyramidal geometry (Figure 7)
with an average ThꢀC(ring) distance of 2.879(10) Å. The cyclo-
pentadienyl rings adopt a nearly eclipsed conformation. The
structural parameters of the [N(p-tolyl)C(SSiMe3)ꢀS] group
indicate a charge delocalization over the N(1)ꢀC(42)ꢀS(1)
unit. The Cp(cent)ꢀThꢀCp(cent) angle is 134.6(3)°. The ThꢀS
and ThꢀN distances are 2.890(3) and 2.587(8) Å, respectively.
These values are similar to those listed in 13 and 14 (Table 1).
The ThꢀCl distance is 2.632(2) Å, identical to that found in [η5-
1,3-(Me3Si)2C5H3]2ThCl2,27 but slightly shorter than that
(2.647(1) Å) found in 11.
Figure 7. Molecular structure of 19 (thermal ellipsoids drawn at the
35% probability level).
2.4. Computational Studies. As demonstrated above, the
imido complex [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4) is
a useful precursor for the preparation of oxo and sulfido com-
plexes [η5-1,2,4-(Me3C)3C5H2]2ThdE (E = O (5) and S (15)).
Complexes 5 and 15 cannot be isolated, but the reaction
chemistry has been explored. The oxo 5 acts as a nucleophile
toward alkylsilyl halides, while sulfido 15 does not. The oxo 5 and
sulfido 15 cannot undergo cycloaddition reactions with alkynes,
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Figure 8. Energy profile (kcal molꢀ1) for the reaction of 4 with Ph2CO.
[Th] = [η5-1,2,4-(Me3C)3C5H2]2Th.
Figure 10. Energy profile (kcal molꢀ1) for the reaction of 5 with Ph2CO,
Me3SiCl, and PhCtCPh. [Th] = [η5-1,2,4-(Me3C)3C5H2]2Th.
two transition states TS4ꢀ5 and TS4ꢀ5a. Intermediate
INT4ꢀ5 is unstable with a Gibbs free energy of +11.0
kcal/mol relative to 4+Ph2CdO, but its relative electronic
energy is ca. 8.4 kcal/mol lower than that of 4+Ph2CdO. The
relative electronic energy (ꢀ22.6 kcal/mol) and free energy
(ꢀ23.4 kcal/mol) of 5+Ph2CdN(p-totyl) as compared to that of
4+Ph2CdO indicate that the formation of 5+Ph2CdN(p-totyl)
is energetically favorable (Figure 8). Furthermore, the potential
energy profile suggests a short lifetime of intermediate INT4ꢀ5,
consistent with the experimental observation that the INT4ꢀ5
cannot be isolated from the reaction mixture. Thus, the forma-
tion of 5 is expected to proceed smoothly. However, the
monomeric oxo 5 cannot be isolated due to its potential reaction
with another equivalent of Ph2CO or due to dimerization.
The mechanism for the reaction of 5 with Ph2CO involves the
stable complex COM1O and the transition state TS1O
(Figure 9). In TS1O, the two forming bond distances of ThꢀO
and OꢀC are 2.475 and 2.118 Å, respectively, about 0.273 and
0.691 Å longer than those in product 7 (Table 1). Once the
COM1O is formed, it is difficult to go back to 5+Ph2CO. The
energy barrier for COM1O to 7 is 13.0 kcal/mol (Figure 10),
which is readily overcome and consistent with the experimentally
observed temperature of ca. 20 °C. The energy barrier of the
dimerization pathway of 5 is expected to be slightly higher than
that of the reaction of 5+Ph2CdO due to pronounced steric
hindrance.
Figure 9. Optimized (B3LYP/genecp) transition state structures (TS;
bond lengths in Å; the hydrogen atoms omitted for clarity) for the
reaction of 5 with PhCtCPh, Me3SiCl, and Ph2CO, reaction of 8 with
Me3SiCl, and reaction of 15 with Me3SiCl and Ph2CS.
but exhibit [2 + 2] cycloaddition behavior with Ph2CO or Ph2CS.
To further rationalize these observations, DFT calculations have
been performed.
The formation of 5 from 4+Ph2CdO proceeds in two steps,
which involve a four-membered ring intermediate INT4ꢀ5 and
The reaction of 5 with Me3SiCl may proceed in two different
ways, that is, SN2 (TS2O) and addition (TS2Oa) mechanisms
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Figure 11. Isosurfaces and energies of the MOs of 5 (top) and 15 (bottom) (the hydrogen atoms omitted for clarity).
(Figure 9). The optimized bond distances of OꢀSi and SiꢀCl in
TS2O are 2.220 and 2.323 Å, respectively, indicating that the
OꢀSi bond is formed and the SiꢀCl bond is broken simulta-
neously, and the resulting Clꢀ anion goes to the Th atom to form
a ThꢀCl bond when it leaves the Si atom. The Si atom in
Me3SiCl can readily approach the O atom, and the energy barrier
for the SN2 process is only 7.4 kcal/mol (Figure 10). Hence,
the reaction can readily proceed at ambient temperature. The
HOMO (Figure 11) of 5 may also account for this pathway
because it is mainly the lone pair of the O atom and can therefore
readily attack the Si in Me3SiCl to release Clꢀ. The addition
reaction occurs via the concerted transition state TS2Oa, in
which the two forming bond distances of ThꢀCl and SiꢀO are
2.999 and 2.318 Å, respectively, about 0.352 and 0.673 Å longer
than those in product 11 (Table 1). These combined with the
SiꢀCl distance of 2.294 Å indicate that the OꢀSi and ThꢀCl
bonds are formed while the SiꢀCl bond is broken simulta-
neously. The addition reaction of 5 with Me3SiCl has also a low
activation barrier (11.9 kcal/mol) (Figure 10), but the SN2
reaction seems to be energetically more favorable. In any case,
the activation barriers for the SN2 and the addition mechanisms
are lower than that for the reaction of 5 with Ph2CO, consistent
with the experimental observations that 5 reacts faster with
alkylsilyl halides than with Ph2CdO. Furthermore, on addition
of THF to a C6D6 solution of 5, the adduct 8 is rapidly formed.
The calculated ThꢀO(THF) distance is 2.655 Å, and 8 is ca.
7.8 kcal/mol more stable than 5+THF. Reaction of 8 with Me3SiCl
can proceed in a SN2 fashion via the transition state TS2O-THF
(Figure 9), and the energy barrier from 8 to 11 is 12.3 kcal/mol,
which is consistent with the experiment that the product 11 is
readily formed on reaction of 8 with Me3SiCl at ambient tem-
perature. However, on coordination of a THF molecule to 5, the
tert-butyl groups are pushed away to accommodate the additional
ligand, which increases the steric pressure between the tert-butyl
groups on other side. Consequently, the imposed steric bulk
makes the addition reaction of Me3SiCl via TS2Oa less
favorable.
are ThꢀC (2.776 Å) and CꢀO (2.119 Å) (Figure 9). On the
basis of the frontier molecular orbital (FMO) arguments, the
interaction of the HOMOꢀ6 (Figure 11) of 5 with the LUMO of
PhCtCPh and the interaction of the LUMO (Figure 11) of 5
with the HOMO of PhCtCPh contribute significantly to the
stability of TS3O. The energy barrier is 21.8 kcal/mol (Figure 10),
and therefore much higher than those for 5+Ph2CdO and
5+Me3SiCl. Steric reasons makethe addition reaction to an adduct
of 5 such as 8 less favorable, and therefore THF dissociation must
precede the cycloaddition reaction. Similar to the uranium oxo
metallocene [η5-1,2,4-(Me3C)3C5H2]2UO,3e 5 can rapidly co-
ordinate Lewis bases such as Ph2CO to form 5+Ph2CO, or
alternatively coordinate to another molecule of 5 to give the
dimer 5+5. This blocks 5 against the approach of PhCtCPh, and
the adducts 5+Ph2CO and 5+5 can then undergo cycloaddition
or dimerization leading to metallacycle 7 and dimer 6, respec-
tively. Thus, the experimental observations are in complete
agreement with the observed nucleophilicity of the polarized
Th+ꢀOꢀ moiety13 with alkylsilyl halides, cycloaddition with
Ph2CO, or self-dimerization of the oxo 5, but it does not undergo
cycloaddition reactions with alkynes at room temperature.
The computational results may also explain the experimental
observation that the sulfido 15 can easily react with Ph2CdS to
give the cyclometallocene 18 at room temperature with the
activation barrier of 8.4 kcal/mol (Figure 12). Two types of FMO
interactions stabilize the transition state TS3S (Figure 9), the
interaction of LUMO (Figure 11) of 15 with HOMO of Ph2CS
and the interaction of HOMOꢀ2 (Figure 11) of 15 with LUMO
of Ph2CS. The transition state TS2Sa (Figure 9) for the addition
reaction of 15 with Me3SiCl has been located and shows an
energy barrier of 18.1 kcal/mol, which is about 9.7 kcal/mol
higher than that for 15+Ph2CS (Figure 12). Despite extensive
efforts, the SN2 transition state has not been located. This might
be due to the significantly reduced nuclophilicity of 15 as com-
pared to 5. From the FMOs, the energy differences between lone-
pair orbital (HOMOꢀ1) and π orbitals (HOMO and HOMO
ꢀ2) in 15 are ꢀ4.5 and 3.3 kcal/mol (Figure 11), respectively,
while those between the lone-pair orbital (HOMO) and π
orbitals (HOMOꢀ5 and HOMOꢀ6) in 5 are 48.6 and
The [2 + 2] cycloaddition of 5 with PhCtCPh proceeds via
the transition state TS3O, and the two forming bond distances
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uranium metallocenes. Furthermore, complex 5 also provides a
well-defined molecular model for the heterogeneous reaction of
solid ThO2 and chlorocarbons vapor at high temperature (450ꢀ
500 °C) that results in ThCl4.14
In addition, thorium oxo and sulfido metallocenes exhibit
quite different reactivity patterns; for example, [η5-1,2,4-(Me3C)3-
C5H2]2ThO (5) can be stabilized by 4-dimethylaminopyridine
(dmap), while [η5-1,2,4-(Me3C)3C5H2]2ThS (15) cannot. Sul-
fido 15 undergoes cycloaddition with Ph2CS, while oxo 5 exhibits
increased nucleophilicity toward alkylsilyl halides and reduced
cycloaddition behavior with Ph2CO when compared to 15. This
shows that the reactivity of actinide metallocenes carrying AndE
(E = heteroatom) functional groups is strongly influenced by the
size of the heteroatom anion and the electronic effects associated
with the AndX bonds. Furthermore, the computational studies
indicate that for oxo 5, the energy barrier for nucleophilic
substitution is lower than that for the cycloaddition reaction
with Ph2CO. However, for sulfido 15, the energy barrier of
nucleophilic substitution is higher than that of the cycloaddition
reaction with Ph2CS due to the steric and electronic effects.
In conclusion, the base-free terminal imido thorium metallo-
cene 4 is a useful precursor for the synthesis of the first terminal
oxo and sulfido thorium metallocenes and enabled us to system-
atically probe the intrinsic reactivity of ThdE (E = O and S)
bonds. These results open new ways to design and synthesize
organoactinide metallocenes with terminal multiple bonds. In
addition, these results should significantly expand the range of
possibilities in chemical transformations not only for organoac-
tinide oxo and sulfido complexes but also for solid-state actinide
metal oxides and sulfides. We are planning to synthesize other
organoactinide complexes with multiple bonds (e.g., selenido
and tellurido complexes) to understand the nature of these bonds
and their intrinsic reactivity. Work along these lines is currently in
progress.
Figure 12. Energy profile (kcal/mol) for the reactions of 15+Ph2CS
and 15+Me3SiCl. [Th] = [η5-1,2,4-(Me3C)3C5H2]2Th.
50.7 kcal/mol (Figure 11), respectively. Thus, the reaction of
15+Ph2CS becomes dominant, which is in agreement with the
experimental observation that 15 does not show nucleophilic
behavior toward alkylsilyl halides, but it does undergo a cycload-
dition reaction with Ph2CdS in contrast to the observations for 5.
For oxo 5, the nucleophilic behavior with alkylsilyl halides
dominates over the cycloaddition with Ph2CO.
3. SUMMARY
4. EXPERIMENTAL SECTION
Exchanging Th4+ for U4+ has a pronounced effect on the reac-
tivity of the corresponding metallocenes. For example, the
uranium(IV) oxo metallocene forms a stable pyridine adduct,
[η5-1,2,4-(Me3C)3C5H2]2UO(py),3e while the thorium(IV) oxo
metallocene adduct, [η5-1,2,4-(Me3C)3C5H2]2ThO(py) (9), is
unstable. A monomerꢀdimer equilibrium exists for the base-free
uranium oxo comples [η5-1,2,4-(Me3C)3C5H2]2UO in solution,3e
but the thorium derivative [η5-1,2,4-(Me3C)3C5H2]2ThO di-
merizes irreversibly to {η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2
(6). Mixing [η5-1,2,4-(Me3C)3C5H2]2UO with 1 equiv of
Ph2CO forms the adduct, [η5-1,2,4-(Me3C)3C5H2]2UO-
(OCPh2),3e while [η5-1,2,4-(Me3C)3C5H2]2ThO (5) under-
goes a [2 + 2] cycloaddition to yield [η5-1,2,4-(Me3C)3-
C5H2]2Th[(μ-O)2(CPh2)] (7). This shows how sensitive
actinide oxo metallocenes react with respect to the size of the
metal ion and the electron-donating capabilities of the Lewis base.
However, the uranium3e and thorium oxo metallocenes show
very similar reactivity patterns; for example, both derivatives
show nucleophilic behavior with alkylsilyl halides resembling that
of (η5-C5Me5)2ZrO(py),8d but they do not undergo cycloaddi-
tion reactions with alkynes in contrast to (η5-C5Me5)2TiO(py)8a
and (η5-C5Me5)2ZrO,8b supporting the notion that Th4+ be-
haves more like an actinide than a transition metal.10c Computa-
tional studies reveal that the energy barrier of the nucleophilic
substitution reaction is lower than that of cycloaddition reaction
for 5. This study may also explain the similar behavior for oxo
General Procedures. All reactions and 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. MeCtCMe and CS2 were freshly
distilled from CaH2 immediately prior to use. Me3SiX (X = Cl, CN)
were distilled under nitrogen prior to use. PhCtCPh, Ph2CO, and p-
MeC6H4NH2 were purified by sublimation. [η5-1,2,4-(Me3C)3C5H2]K,28
ThCl4(tmeda)2,29 and Ph2CS30 were prepared according to literature
methods. All other chemicals were purchased from Aldrich Chemical
Co. and Beijing Chemical Co. used as received unless otherwise noted.
Infrared spectra were obtained from KBr pellets on an Avatar 360
Fourier transform spectrometer. 1H and 13C{1H} NMR spectra were re-
corded on a Bruker AV 400 spectrometer at 400 and 100 MHz,
respectively. All chemical shifts were reported in δ units with reference
to the residual protons of the deuterated solvents, which were 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.
Preparation of [η5-1,2,4-(Me3C)3C5H2]2ThCl2 (1). After a
toluene (50 mL) suspension of [η5-1,2,4-(Me3C)3C5H2]K (5.00 g,
18.4 mmol) and ThCl4(tmeda)2 (5.52 g, 9.1 mmol) was refluxed for 3
days, the mixture was filtered, and the residue was washed with toluene
(5 mL ꢁ 3). The volume of the filtrate was reduced to ca. 20 mL, and
colorless crystals of 1 were isolated when this solution was kept at room
temperature for 2 days. Yield: 5.95 g (85%). Mp: 180ꢀ182 °C. 1H NMR
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(C6D6): δ 6.56 (s, 4H, ring CH), 1.59 (s, 36H, (CH3)3C), 1.31 (s, 18H,
(CH3)3C). 13C{1H} NMR (C6D6): δ 147.3, 146.9, 119.1, 35.3, 33.8,
33.7, 32.5. IR (KBr, cmꢀ1): ν 2955 (s), 2870 (m), 1598 (s), 1460 (s),
1391 (s), 1360 (s), 1259 (s), 1235 (s), 1018 (s), 800 (s). Anal. Calcd for
C34H58Cl2Th: C, 53.05; H, 7.59. Found: C, 53.12; H, 7.53.
(s), 1238 (s), 1093 (s), 1019 (s), 797 (s), 752 (s), 726 (s), 693 (s), 657
(s). Anal. Calcd for C82H132O2Th2: C, 61.02; H, 8.24. Found: C, 61.13;
H, 8.22.
Method B. NMR Scale. ToaJ. Young NMRtubechargedwitha solution
of [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol)
in C6D6 (0.5 mL) was added benzophenone (3.6 mg, 0.02 mmol).
The resonances due to {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6) along
with those of Ph2CdN(p-tolyl) ((1H NMR (C6D6): δ 7.97 (m, 2H, aryl),
7.12 (m, 3H, aryl), 6.98 (m, 2H, aryl), 6.89 (m, 3H, aryl), 6.77 (m, 4H,
Preparation of [η5-1,2,4-(Me3C)3C5H2]2ThMe2 (2). A diethyl
ether (34.6 mL) solution of MeLi (0.15 M in diethyl ether; 5.2 mmol)
was slowly added to a diethyl ether (25 mL) solution of [η5-
1,2,4-(Me3C)3C5H2]2ThCl2 (1; 2.00 g, 2.6 mmol) with stirring at room
temperature. After the solution was stirred for 1 h at room temperature,
the solvent was removed. The residue was extracted with n-hexane
(15 mL ꢁ 3) and filtered. The volume of the filtrate was reduced to ca.
10 mL and cooled to ꢀ20 °C, yielding colorless crystals, which were
isolated by filtration. Yield: 1.50 g (79%). Mp: 165ꢀ170 °C (dec.). 1H
NMR (C6D6): δ 6.28 (s, 4H, ring CH), 1.54 (s, 36H, (CH3)3C), 1.26 (s,
18H, (CH3)3C), 0.46 (s, 6H, ThCH3). 13C{1H} NMR (C6D6): δ 142.5,
141.2, 113.5, 58.9, 34.9, 34.2, 32.8, 32.6. IR (KBr, cmꢀ1): ν 3092 (w),
2956 (s), 2849 (s), 1611 (w), 1482 (s), 1455 (s), 1391 (s), 1358 (s),
1235 (s), 1165 (s), 1107 (s), 1000 (s), 958 (s), 824 (s), 780 (s). Anal.
Calcd for C36H64Th: C, 59.32; H, 8.85. Found: C, 59.33; H, 8.78.
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)2 (3).
A toluene (10 mL) solution of p-toluidine (0.59 g, 5.5 mmol) was added
to a toluene (10 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2ThMe2 (2;
2.00 g, 2.75 mmol). After the mixture was stirred at 70 °C for 2 days, the
solvent was removed under reduced pressure. The residue was extracted
with n-hexane (10 mL ꢁ 3) and filtered. The volume of the filtrate was
reduced to 10 mL and cooled to ꢀ20 °C, yielding colorless crystals, which
were isolated by filtration. Yield: 2.25 g (90%). Mp: 136ꢀ138 °C (dec.).
1H NMR (C6D6): δ 7.06 (d, J = 8.0 Hz, 4H, aryl), 6.84 (d, J = 8.0 Hz, 4H,
aryl), 6.58 (s, 4H, ring CH), 5.07(s, 2H, NH), 2.22 (s, 6H, tolylCH3), 1.42
(s, 36H, (CH3)3C), 1.41 (s, 18H, (CH3)3C). 13C{1H} NMR (C6D6): δ
154.3, 144.8, 143.9, 129.5, 126.5, 119.0, 115.5, 34.9, 34.1, 33.9, 32.7, 20.5.
IR (KBr, cmꢀ1): ν 3254 (m), 2962 (s), 2844 (m), 1606 (s), 1503 (s),
1448 (s), 1393 (s), 1354 (s), 1259 (s), 1162 (s), 1107 (s), 1022 (s), 957
(s), 806 (s). Anal. Calcd for C48H74N2Th: C, 63.27; H, 8.19; N, 3.07.
Found: C, 63.23; H, 8.21; N, 2.98.
1
aryl), 1.97 (s, 3H, CH3))3e were observed by H NMR spectroscopy
(100% conversion).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-O)2CPh2]
(7). Method A. A benzene (5 mL) solution of benzophenone (0.24 g,
1.32 mmol) was added to a benzene (10 mL) solution of [η5-1,2,4-
(Me3C)3C5H2]2ThdN(p-tolyl) (4; 0.50 g, 0.62 mmol) with stirring at
room temperature. After this solution was stirred overnight at room
temperature, the solution was filtered. The volume of the filtrate was
reduced to 5 mL and cooled to ꢀ20 °C, yielding colorless crystals 7,
which were isolated by filtration. Yield: 0.47 g (85%). Mp: 160ꢀ162 °C
(dec.). 1HNMR(C6D6): δ7.84 (d, J=7.6Hz, 4H, aryl), 7.23(t, J=7.6 Hz,
4H, aryl), 7.05 (m, 2H, aryl), 6.48 (d, J = 3.2 Hz, 2H, ring CH), 5.93 (d, J =
3.2 Hz, 2H, ring CH), 1.60 (s, 18H, (CH3)3C), 1.59 (s, 18H, (CH3)3C),
1.19 (s, 18H, (CH3)3C). 13C{1H} NMR (C6D6): δ 151.6, 144.8, 142.5,
140.5, 129.9, 126.7, 126.5, 118.0, 116.3, 94.2, 34.9, 34.8, 33.6, 32.9,
32.4, 31.4. IR (KBr, cmꢀ1): ν 2961 (s), 1613 (s), 1592 (s), 1446 (s),
1359 (s), 1260 (s), 1069 (s), 1016 (s), 801 (s), 745 (s), 698 (s),
671 (s). Anal. Calcd for C47H68O2Th: C, 62.93; H, 7.64. Found: C,
63.13; H, 7.62.
Method B. NMR Scale. To a J. Young NMR tube charged with a sol-
utionof [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol)
in C6D6 (0.5 mL) was added benzophenone (7.2 mg, 0.04 mmol). The
resonances due to [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-O)2CPh2] (7)
along with those of Ph2CdN(p-tolyl) were observed by 1H NMR spec-
troscopy (100% conversion).
Reaction of [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-O)2CPh2] (7)
with Me3SiCl. NMR Scale. To a J. Young NMR tube charged with
[η5-1,2,4-(Me3C)3C5H2]2Th[(μ-O)2CPh2] (7; 18 mg, 0.02 mmol) and
C6D6 (0.5 mL) was added an excess of Me3SiCl. The resonances due to
[η5-1,2,4-(Me3C)3C5H2]2ThCl2 (1) along with those of Ph2C-
(OSiMe3)2 ((1H NMR (C6D6): δ 7.68 (d, J = 7.4 Hz, 2H, aryl), 7.08
Preparation of [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4).
After a toluene (20 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2ThMe2
(2; 0.80 g, 1.1 mmol) and [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)2
(3; 1.0 g, 1.1 mmol) was refluxed for 4 days with stirring, the solution was
filtered, and the volume of the filtrate was reduced to 5 mL and cooled
to ꢀ20 °C, yielding colorless crystals. Yield: 1.50 g (85%). Mp:
198ꢀ200 °C. 1H NMR (C6D6): δ 7.12 (d, J = 8.0 Hz, 2H, aryl), 6.52
(s, 4H, ring CH), 6.48 (d, J = 8.0 Hz, 2H, aryl), 2.33 (s, 3H, tolylCH3),
1.52 (s, 36H, (CH3)3C), 1.44 (s, 18H, (CH3)3C). 13C{1H} NMR
(C6D6): δ 158.1, 139.9, 137.7, 128.6, 123.9, 122.7, 116.8, 34.3, 33.8,
32.8, 29.8, 20.6. IR (KBr, cmꢀ1): ν 2958 (s), 1599 (s), 1471 (s), 1455
(s), 1358 (s), 1260 (s), 1235 (s), 1162 (m), 1097 (s), 1019 (s), 916 (s),
803 (s). Anal. Calcd for C41H65NTh: C, 61.25; H, 8.15; N, 1.74. Found:
C, 61.23; H, 8.16; N, 1.76.
1
(m, 8H, aryl), 0.18 (s, 18H, (CH3)3Si)) were observed by H NMR
spectroscopy (100% conversion).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2ThO(THF) (8). NMR
Scale. To a J. Young NMR tube charged with [η5-1,2,4-(Me3C)3-
C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol), C6D6 (0.5 mL), and an
excess of THF was added benzophenone (3.6 mg, 0.02 mmol). The
resonances due to [η5-1,2,4-(Me3C)3C5H2]2Th(O)(THF) (8) (1H
NMR (C6D6): δ 6.46 (d, J = 3.2 Hz, 2H, ring CH), 5.87 (d, J =
3.2 Hz, 2H, ring CH), 3.56(m, THF),1.58(s, 18H, (CH3)3C), 1.57 (s, 18H,
(CH3)3C), 1.45 (m, THF), 1.14 (s, 18H, (CH3)3C)) along with those of
Ph2CdN(p-tolyl) were observed by 1H NMR spectroscopy (100%
conversion). No change was detected by 1H NMR spectroscopy when
the sample was kept at room temperature for 1 week. However, when the
solvent was removed or this solution was heated at 65 °C, resonances
due to {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6) were observed by
1H NMR spectroscopy (100% conversion).
Preparation of {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 2C7H8
3
(6 2C7H8). Method A. A toluene (5 mL) solution of benzophenone
3
(0.12 g, 0.66 mmol) was added to a toluene (10 mL) solution of [η5-
1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 0.50 g, 0.62 mmol) with stir-
ring at room temperature. After this solution was stirred at room tem-
perature for 0.5 h, the solution was filtered. The volume of the filtrate
was reduced to 5 mL and cooled to ꢀ20 °C, yielding colorless crystals
Preparation of [η5-1,2,4-(Me3C)3C5H2]2ThO(py) (9). NMR
Scale. To a J. Young NMR tube charged with [η5-1,2,4-(Me3C)3-
C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.020 mmol), C6D6 (0.5 mL), and an
excess of pyridine was added benzophenone (3.6 mg, 0.02 mmol). The
resonances due to [η5-1,2,4-(Me3C)3C5H2]2Th(O)(py) (9) (1H NMR
(C6D6): δ 8.78 (m, py), 6.94 (m, py), 6.64 (m, py), 6.48 (d, J = 3.4 Hz,
2H, ring CH), 5.92 (d, J = 3.4 Hz, 2H, ring CH), 1.60 (s, 18H,
(CH3)3C), 1.59 (s, 18H, (CH3)3C), 1.18 (s, 18H, (CH3)3C)) along
6 2C7H8, which were isolated by filtration. Yield: 0.41 g (81%). Mp:
3
>300 °C. 1H NMR (C6D6): δ 7.04 (m, 6H, tolyl), 6.95 (m, 4H, tolyl),
6.68 (s, 4H, ring CH), 6.08 (s, 4H, ring CH), 2.11 (s, 6H, tolylCH3), 1.71
(s, 36H, (CH3)3C), 1.69 (s, 36H, (CH3)3C), 1.52 (s, 36H, (CH3)3C).
13C{1H} NMR (C6D6): δ 141.4, 140.8, 137.6, 136.2, 129.1, 127.5,
125.4, 115.8, 112.7, 35.9, 34.9, 34.4, 33.8, 32.8, 32.5, 21.4. IR
(KBr, cmꢀ1): ν 2962 (s), 1619 (s), 1502 (s), 1446 (s), 1357 (s), 1261
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1
with those of Ph2CdN(p-tolyl) were observed by H NMR spectros-
0.62 mmol) and Me3SiCN (1.0 mL) and benzophenone (0.12 g,
0.66 mmol) in toluene (25 mL) and recrystallization from an n-hexane
solution by a procedure similar to that in the synthesis of 11 (method A).
Yield: 0.40 g (80%). Mp: 203ꢀ205 °C (dec.). 1H NMR (C6D6): δ 6.33
(s, 2H, ring CH), 6.30 (s, 2H, ring CH), 1.61 (s, 18H, (CH3)3C), 1.51 (s,
18H, (CH3)3C), 1.38 (s, 18H, (CH3)3C), 0.34 (s, 9H, (CH3)3Si).
13C{1H} NMR (C6D6): δ 145.8, 145.2, 144.7, 130.0, 118.8, 116.1, 34.9,
34.3, 34.2, 34.0, 33.7, 32.2, 3.3. IR (KBr, cmꢀ1): ν 2961 (m), 2850 (m),
2039 (m), 1449 (m), 1260 (s), 1090 (s), 1019 (s), 798 (s). Anal. Calcd
for C38H67NOSiTh: C, 56.06; H, 8.30; N, 1.72. Found: C, 56.00; H,
8.28; N, 1.67.
Method B. NMR Scale. Benzophenone (3.6 mg, 0.02 mmol) was
added to a J. Young NMR tube charged with [η5-1,2,4-(Me3C)3C5H2]2-
ThdN(p-tolyl) (4; 16 mg, 0.02 mmol), C6D6 (0.5 mL), and an excess of
THF. After 10 min, an excess of Me3SiCN was added to the mixture. The
resonances due to [η5-1,2,4-(Me3C)3C5H2]2Th(OSiMe3)(CN) (12)
along with those of Ph2CdN(p-tolyl) were observed by 1H NMR
spectroscopy (100% conversion).
Reaction of {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6) with
Me3SiX (X = Cl, CN). NMR Scale. To a J. Young NMR tube charged
with {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6; 16 mg, 0.01 mmol)
and C6D6 (0.5 mL) was added an excess of Me3SiX (X = Cl, CN). In
each case, the sample was monitored periodically by 1H NMR spectros-
copy, and no change was detected in the 1H NMR spectrum when the
sample was heated at 65 °C for 3 days.
1
copy (100% conversion). No change was detected by H NMR spec-
troscopy when the sample was kept at room temperature for 1 week.
However, when the solvent was removed or this solution was heated at
65 °C, resonances due to {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6)
were observed by 1H NMR spectroscopy (100% conversion).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2ThO(dmap) (10). A
THF (5 mL) solution of benzophenone (120 mg, 0.66 mmol) was added
to a THF (10 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-
tolyl) (4; 500 mg, 0.62 mmol) and 4-dimethylaminopyridine (dmap;
80 mg, 0.65 mmol) with stirring at room temperature. After this solution
was stirred at room temperature for 0.5 h, the solution was filtered. The
volume of the filtrate was reduced to 5 mL and cooled to ꢀ20 °C,
yielding colorless crystals 10, which were isolated by filtration. Yield:
415mg(75%). Mp:138ꢀ140 °C(dec.). 1H NMR(C6D6): δ8.88 (s, 2H,
dmap), 6.40 (s, 2H, ring CH), 6.34 (s, 2H, ring CH), 5.99 (s, 2H, dmap),
1.99 (s, 6H, NCH3), 1.89 (s, 18H, (CH3)3C), 1.78 (s, 18H, (CH3)3C),
1.29 (s, 18H, (CH3)3C). 13C{1H} NMR (C6D6): δ 152.5, 139.1, 138.9,
138.2, 129.1, 113.4, 113.0, 106.3, 44.6, 37.9, 35.5, 35.0, 33.9, 32.7, 32.6.
IR (KBr, cmꢀ1): ν 2961 (m), 1612 (s), 1445 (m), 1391 (m), 1352 (m),
1260 (s), 1089 (s), 1019 (s), 1002 (s), 801 (s), 724 (s). Anal. Calcd for
C41H68N2OTh: C, 58.83; H, 8.19; N, 3.35. Found: C, 58.78; H, 8.21; N,
3.36. No change was detected by 1H NMR spectroscopy when a sample
of 10 was kept at room temperature for 1 week. However, when the
sample was heated at 65 °C, resonances due to {[η5-1,2,4-(Me3C)3-
C5H2]2Th}2(μ-O)2 (6) were observed by 1H NMR spectroscopy
(100% conversion).
Reaction of [η5-1,2,4-(Me3C)3C5H2]2ThO(THF) (8) or [η5-
1,2,4-(Me3C)3C5H2]2ThO(py) (9) with R0C;CR0 (R0 = Me, Ph,
Me3Si), CH2dCH2, Me3CCl, or C6H5Cl. NMR Scale. Benzophe-
none (3.6 mg, 0.02 mmol) was added to a J. Young NMR tube charged
with [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol),
C6D6 (0.5 mL), and an excess of THF or pyridine. After 10 min, an
excess of R0CtCR0 (R0 = Me, Ph, Me3Si), CH2dCH2, Me3CCl, or
C6H5Cl was added. In each case, the sample was monitored periodically
by 1H NMR spectroscopy, and the spectrum did not show any change
when kept at room temperature for 3 days. However, when the solution
was heated at 65 °C, resonances due to {[η5-1,2,4-(Me3C)3C5H2]2-
Th}2(μ-O)2 (6) were observed by 1H NMR spectroscopy (100%
conversion).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th(OSiMe3)(Cl)
(11). Method A. A toluene (5 mL) solution of benzophenone (0.12 g,
0.66 mmol) was added to a toluene (20 mL) solution of [η5-1,2,4-
(Me3C)3C5H2]2ThdN(p-tolyl) (4; 0.50 g, 0.62 mmol) and Me3SiCl
(1.0 mL) with stirring at room temperature. After the solution was
stirred at room temperature for 1 h, the solvent was removed. The res-
idue was extracted with n-hexane (10 mL ꢁ 3) and filtered. The volume
of the filtrate was reduced to 5 mL and cooled to ꢀ20 °C, yielding
colorless crystals, which were isolated by filtration. Yield: 0.43 g (84%).
Mp: 220ꢀ222 °C (dec.). 1H NMR (C6D6): δ 6.40 (d, J = 3.2 Hz, 2H,
ring CH), 6.38 (d, J = 3.2 Hz, 2H, ring CH), 1.62 (s, 18H, (CH3)3C),
1.56 (s, 18H, (CH3)3C), 1.40 (s, 18H, (CH3)3C), 0.35 (s, 9H,
(CH3)3Si). 13C{1H} NMR (C6D6): δ 145.4, 144.5, 144.3, 118.9, 115.6,
35.1, 34.5, 34.1, 34.0, 33.9, 32.3, 3.2. IR (KBr, cmꢀ1): ν 2959 (m),
2904 (m), 2868 (m), 1482 (s), 1455 (s), 1390 (s), 1358 (s), 1260 (s),
1236 (s), 1163 (s), 1095 (s), 1021 (s), 892 (s), 805 (s). Anal. Calcd for
C37H67ClOSiTh: C, 53.96; H, 8.20. Found: C, 54.12; H, 8.21.
Reaction of [η5-1,2,4-(Me3C)3C5H2]2ThO (5) with R0C;CR0
(R0 = Me, Ph, Me3Si). NMR Scale. [η5-1,2,4-(Me3C)3C5H2]2-
ThdN(p-tolyl) (4; 16 mg, 0.02 mmol) was added to a J. Young NMR
tube charged with benzophenone (3.6 mg, 0.02 mmol), C6D6 (0.5 mL),
and an excess of R0CtCR0 (R0 = Me, Ph, Me3Si). In each case, the
resonances due to {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-O)2 (6) along
Method B. NMR Scale. Benzophenone (7.2 mg, 0.04 mmol) was
added to a J. Young NMR tube charged with [η5-1,2,4-(Me3C)3-
C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol), C6D6 (0.5 mL), and
an excess of Me3SiCl. The resonances due to [η5-1,2,4-(Me3C)3C5H2]2-
Th(OSiMe3)(Cl) (11) along with those of Ph2CdN(p-tolyl) were
1
with those of Ph2CdN(p-tolyl) were observed by H NMR spectros-
copy (100% conversion). Each sample was monitored periodically by 1H
NMR spectroscopy, and no change was detected by 1H NMR spectros-
copy when the sample was heated at 65 °C for 3 days.
1
Reaction of [η5-1,2,4-(Me3C)3C5H2]2ThO (5) with Me3CCl
or C6H5Cl. NMR Scale. Benzophenone (3.6 mg, 0.02 mmol) was
added to a J. Young NMR tube charged with [η5-1,2,4-(Me3C)3C5H2]2-
ThdN(p-tolyl) (4; 16 mg, 0.02 mmol), C6D6 (0.5 mL), and an excess of
Me3CCl or C6H5Cl. In each case, the resonances due to {[η5-1,2,4-
(Me3C)3C5H2]2Th}2(μ-O)2 (6) along with those of Ph2CdN(p-tolyl)
observed by H NMR spectroscopy (100% conversion). This sample
was maintained at 65 °C and monitored periodically by 1H NMR
spectroscopy. After 1 day, conversion to [η5-1,2,4-(Me3C)3C5H2]2ThCl2
(1) was 65%, and after 2 days, complete conversion to [η5-1,2,4-
(Me3C)3C5H2]2ThCl2 (1) was achieved.
Method C. NMR Scale. Benzophenone (3.6 mg, 0.02 mmol) was
added to a J. Young NMR tube charged with [η5-1,2,4-(Me3C)3-
C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol), C6D6 (0.5 mL),
and an excess of pyridine. After 10 min, an excess of Me3SiCl was
added to the mixture. The resonances due to [η5-1,2,4-(Me3
C)3C5H2]2Th(OSiMe3)(Cl) (11) along with those of Ph2CdN(p-
tolyl) were observed by 1H NMR spectroscopy (100% conversion).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th(OSiMe3)(CN)
(12). Method A. This compound was prepared as colorless crystals
from the reaction of [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 0.5 g,
1
were observed by H NMR spectroscopy (100% conversion). Each
1
sample was monitored periodically by H NMR spectroscopy, and no
1
change was detected by H NMR spectroscopy when the sample was
heated at 65 °C for 3 days.
Reaction of [η5-1,2,4-(Me3C)3C5H2]2ThO(THF) (8) or [η5-1,
2,4-(Me3C)3C5H2]2ThO(py) (9) with PhC;CH. NMR Scale.
Benzophenone (3.6 mg, 0.02 mmol) was added to a J. Young NMR
tube charged with [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 16 mg,
0.02 mmol), C6D6 (0.5 mL), and an excess of THF or pyridine. After 10
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Journal of the American Chemical Society
ARTICLE
min, an excess of PhCtCH was added. In each case, the resonances due
(13; 18 mg, 0.02 mmol) and C6D6 (0.5 mL) was added an excess of
RCtCR (R = Me, Ph). In each case, the sample was monitored
3e
to (Me3C)3C5H3 and resonances due to other unidentified thorium
containing compounds were observed by 1H NMR spectroscopy (100%
conversion).
periodically by H NMR spectroscopy. When the solution was heated
1
at 65 °C for 8 h, resonances due to {[η5-1,2,4-(Me3C)3C5H2]2Th}2-
(μ-S)2 (16) along with those of p-tolylNCS were observed by 1H NMR
spectroscopy (100% conversion).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C(S)ꢀS]
(13). A benzene (5 mL) solution of CS2 (47 mg, 0.62 mmol) was
added to a benzene (10 mL) solution of [η5-1,2,4-(Me3C)3-
C5H2]2ThdN(p-tolyl) (4; 500 mg, 0.62 mmol) with stirring at room
temperature. After themixture was stirredatroom temperature for1 h, the
solution was filtered. The volume of the filtrate was reduced to 2 mL, and
Preparation of {[1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CS]}6 6C6H6
3
(17 6C6H6). CS2 (0.5 mL) was added to a benzene (10 mL) solution of
3
[η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C(S)ꢀS] (13; 190 mg, 0.2 mmol).
After this mixture was heated at 65 °C overnight without stirring, yellow
crystals were isolated from the solution, which were identified as
colorless crystals 13 0.5C6H6 were isolated from the mixture after this
3
17 6C6H6 by X-ray diffraction analysis. Yield: 166 mg (94%). Mp:
solution stood at room temperature for 1 week. Yield: 400 mg (70%). Mp:
130ꢀ132 °C (dec.). 1H NMR (C6D6): δ 7.50 (d, J = 8.0 Hz, 2H, aryl),
7.15 (s, 3H, C6H6), 7.13 (d, J = 8.0 Hz, 2H, aryl), 6.41 (d, J = 3.2 Hz, 2H,
ring CH), 6.32 (d, J = 3.2 Hz, 2H, ring CH), 2.19 (s, 3H, tolylCH3), 1.57
(s, 18H, (CH3)3C), 1.43 (s, 18H, (CH3)3C), 1.13 (s, 18H, (CH3)3C).
13C{1H} NMR (C6D6): δ 198.4, 149.0, 146.0, 145.4, 145.1, 134.1, 129.3,
128.0, 126.2, 121.5, 116.8, 36.0, 34.9, 34.7, 34.1, 33.8, 33.6, 20.7. IR
(KBr, cmꢀ1): ν 2961 (s), 1502 (m), 1450 (m), 1358 (m), 1260 (s),
1090(s), 1017 (s), 971 (s), 798 (s). Anal. Calcd for C45H68NS2Th: C,
58.80; H, 7.46; N, 1.52. Found: C, 58.65; H, 7.35; N, 1.56.
3
>300 °C. IR (KBr, cmꢀ1): ν 2961 (s), 1451 (m), 1357 (m), 1261 (s),
1090 (s), 1019 (s), 936 (s), 892 (s), 798 (s). Anal. Calcd for
C246H384S18Th6: C, 55.63; H, 7.29. Found: C, 55.58; H, 7.31. This
compound was insoluble in deuterated solvents such as pyridine, THF,
toluene, and CD2Cl2, which made the characterization by NMR
spectroscopy infeasible. This compound was also prepared in 96% yield
(85 mg) from the reaction of [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl)
(4; 80 mg, 0.1 mmol) with an excess of CS2 (0.2 mL) in benzene
at 65 °C.
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CPh2] (18).
Method A. A benzene (5 mL) solution of Ph2CS (0.25 g, 1.26 mmol) was
added to a benzene (10 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2ThdN-
(p-tolyl) (4; 0.50 g, 0.62 mmol) with stirring at room temperature. After this
solution was stirred for 2 h at room temperature, the solution was filtered.
The volume of the filtrate was reduced to 1 mL, and pale yellow micro-
crystals 18 were isolated from the mixture after this solution stood at room
temperature for 3 days. Yield: 0.43 g (75%). Mp: 185ꢀ187 °C (dec.). 1H
NMR (C6D6): δ 8.24 (d, J = 7.2 Hz, 4H, aryl), 7.19 (t, J = 7.2 Hz, 4H, aryl),
7.01 (t, J = 7.2 Hz, 2H, aryl), 6.48 (s, 2H, ring CH), 6.45 (s, 2H, ring CH),
1.50 (s, 36H, (CH3)3C), 1.27 (s, 18H, (CH3)3C). 13C{1H} NMR (C6D6):
δ 153.3, 146.5, 145.8, 143.8, 128.9, 127.3, 125.7, 120.9, 116.6, 60.9, 35.5,
35.0, 34.0, 33.2, 32.7, 31.3. IR (KBr, cmꢀ1): ν 2962 (s), 1592 (m), 1439
(m), 1409 (m), 1260 (s), 1090 (s), 1018 (s), 798 (s). Anal. Calcd for
C47H68S2Th: C, 60.75; H, 7.38. Found: C, 60.82; H, 7.32.
Method B. NMR Scale. To a J. Young NMR tube charged with a solu-
tion of [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-tolyl) (4; 16 mg, 0.02 mmol)
in C6D6 (0.5 mL) was added Ph2CS (4.0 mg, 0.02 mmol).
The resonances due to [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CPh2] (18)
along with those of Ph2CdN(p-tolyl) and unreacted 4 were observed by
1H NMR spectroscopy (50% conversion based on 4).
Method C. NMR Scale. Ph2CS (4.0 mg, 0.02 mmol) was added to a
J. Young NMR tube charged with [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-
tolyl) (4; 16 mg, 0.02 mmol), C6D6 (0.5 mL), and an excess of Me3SiCl.
The resonances due to [η5-1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CPh2] (18)
along with those of Ph2CdN(p-tolyl) and unreacted 4 were observed
by 1H NMR spectroscopy (50% conversion based on 4).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C(NPh)ꢀS]
(14). A benzene (5 mL) solution of PhNCS (84 mg, 0.62 mmol) was
added to a benzene (10 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2-
ThdN(p-tolyl) (4; 500 mg, 0.62 mmol) with stirring at room tempera-
ture. After the mixture was stirred at room temperature for 1 h, the
solution was filtered. The volume of the filtrate was reduced to 2 mL, and
colorless crystals 14 were isolated from the mixture after this solution
stood at room temperature for 2 days. Yield: 454 mg (78%). Mp:
1
155ꢀ157 °C. H NMR (C6D6): δ 7.63 (d, J = 8.0 Hz, 2H, aryl), 7.40
(t, J = 8.0 Hz, 2H, aryl), 7.33 (d, J = 7.2 Hz, 2H, aryl), 7.14 (d, J = 8.0 Hz,
2H, aryl), 6.99 (m, 1H, aryl), 6.47 (d, J = 3.2 Hz, 2H, ring CH), 6.38 (d, J =
3.2 Hz, 2H, ring CH), 2.20 (s, 3H, tolylCH3), 1.55 (s, 18H, (CH3)3C),
1.42 (s, 18H, (CH3)3C), 1.22 (s, 18H, (CH3)3C). 13C{1H} NMR
(C6D6): δ 152.0, 148.0, 145.8, 145.2, 145.0, 132.0, 129.2, 128.5, 128.3,
124.8, 123.6, 121.8, 120.2, 117.3, 35.6, 34.7, 33.8, 33.7, 33.6, 31.8, 20.7. IR
(KBr, cmꢀ1): ν 2961 (s), 1604 (m), 1557 (s), 1453 (m), 1355 (s), 1260
(s), 1090 (s), 1023 (s), 946(s), 798 (s). Anal. Calcd forC48H70N2STh:C,
61.38; H, 7.51; N, 2.98. Found: C, 61.45; H, 7.45; N, 3.01. The 1H NMR
spectrum of the sample did not show any change when kept at 160 °C
for 3 days.
Preparation of {[η5-1,2,4-(Me3C)3C5H2]2Th}2(μ-S)2 (16. )
Method A. After a benzene (10 mL) solution of [η5-1,2,4-(Me3C)3-
C5H2]2Th[N(p-tolyl)C(S)-S] (13; 190 mg, 0.2 mmol) was stirred at
65 °C overnight, the solution was filtered. The volume of the filtrate was
reduced to 2 mL, and colorless crystals 16 were isolated from the mixture
after this solution stood at room temperature for 2 days. Yield: 120 mg
(82%). Mp: >300 °C. 1H NMR (C6D6): δ 6.85 (d, J = 2.4 Hz, 2H, ring
CH), 6.81 (d, J = 2.4 Hz, 2H, ring CH), 1.91 (s, 18H, (CH3)3C), 1.61 (s,
18H, (CH3)3C), 1.57 (s, 18H, (CH3)3C). 13C{1H} NMR (C6D6):
δ 150.0, 141.5, 137.7, 126.5, 118.0, 116.3, 36.4, 35.4, 34.9, 34.2, 33.3,
33.0. IR (KBr, cmꢀ1): ν 2960 (s), 1511 (m), 1459 (m), 1363 (s), 1259
(s), 1093 (s), 1017 (s), 798 (s). Anal. Calcd for C68H116S2Th2: C, 55.87;
H, 8.00. Found: C, 55.90; H, 7.92.
Method D. NMR Scale. Ph2CS (4.0 mg, 0.02 mmol) was added to a
J. Young NMR tube charged with [η5-1,2,4-(Me3C)3C5H2]2ThdN(p-
tolyl) (4; 16 mg, 0.020 mmol), 4-dimethylaminopyridine (dmap;
2.5 mg, 0.020 mmol), and C6D6 (0.5 mL). The resonances due to
[η5-1,2,4-(Me3C)3C5H2]2Th[(μ-S)2CPh2] (18) along with those of
1
Ph2CdN(p-tolyl) and unreacted 4 were observed by H NMR spec-
Method B. NMR Scale. An NMR sample of [η5-1,2,4-(Me3C)3-
C5H2]2Th[N(p-tolyl)C(S)-S] (13; 19 mg, 0.02 mmol) with C6H6
(0.5 mL) was monitored periodically by 1H NMR spectroscopy. When
the sample was heated at 65 °C for 8 h, resonances due to {[η5-1,2,4-
(Me3C)3C5H2]2Th}2(μ-S)2 (16) along with those of p-tolylNCS ((1H
NMR (C6D6): δ 6.53 (m, 4H, aryl), 1.83 (s, 3H, tolylCH3))31 were
observed by 1H NMR spectroscopy (100% conversion).
troscopy (50% conversion based on 4).
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)-
C(SSiMe3)ꢀS](Cl) (19). Me3SiCl (1.0 mL) was added to a benzene
(10 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C(S)-S] (13;
190 mg, 0.2 mmol) with stirring at room temperature. After this mixture was
stirredovernightat65°C, the solution was filtered. The volume of the filtrate
was reduced to 2 mL, and colorless crystals 19 were isolated from the mixture
after this solution stood at room temperature for 3 days. Yield: 148 mg
(75%). Mp: 108ꢀ110 °C (dec.). 1H NMR (C6D6): δ 7.34 (d, J = 8.0 Hz,
2H, aryl), 7.03 (d, J = 8.0 Hz, 2H, aryl), 6.75 (d, J = 2.8 Hz, 2H, ring CH),
Reaction of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C(S)-S]
(13) with RC;CR (R = Me, Ph). NMR Scale. To a J. Young
NMR tube charged with [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C(S)-S]
13194
dx.doi.org/10.1021/ja205280k |J. Am. Chem. Soc. 2011, 133, 13183–13196

Journal of the American Chemical Society
ARTICLE
6.23 (d, J = 2.8 Hz, 2H, ring CH), 2.09 (s, 3H, tolylCH3), 1.64 (s, 18H,
(CH3)3C), 1.52 (s, 18H, (CH3)3C), 1.44 (s, 18H, (CH3)3C), 0.48 (s, 9H,
(CH3)3Si). 13C{1H} NMR (C6D6): δ 187.0, 146.7, 146.0, 144.2, 143.2,
135.2, 128.8, 125.7, 121.3, 113.2, 35.2, 35.1, 34.9, 34.4, 33.9, 32.5, 20.7, 1.7. IR
(KBr, cmꢀ1): ν 2961 (s), 1604 (m), 1439 (m), 1358 (m), 1260 (s), 1089
(s), 1017 (s), 798 (s). Anal. Calcd for C45H74NClS2SiTh: C, 54.66; H, 7.54;
N, 1.42. Found: C, 54.62; H, 7.61; N, 1.45.
’ ACKNOWLEDGMENT
This work was supported by the National Natural Science
Foundation of China (Grant nos. 20972018, 21074013,
21073016), the Program for New Century Excellent Talents in
University (NCET-10-0253), the Fundamental Research Funds
for the Central Universities (China), and the Deutsche For-
schungsgemeinschaft (DFG) through the Emmy-Noether pro-
gram (WA 2513/2-1). We thank Dr. Xuebin Deng for his help
with the crystallography, and Professor Richard A. Andersen for
helpful discussions.
Preparation of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C{N-
(Ph)(SiMe3)}ꢀS](Cl) (20). Me3SiCl (1.0 mL) was added to a benzene
(10 mL) solution of [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)C-
(NPh)ꢀS] (14; 190 mg, 0.2 mmol) with stirring at room temperature.
After this mixture was stirred overnight at 65 °C, the solution was filtered.
The volume of the filtrate was reducedto 1 mL, and colorless microcrystals
20 were isolated from the mixture after this solution stood at room
temperature for 2 days. Yield: 172 mg (82%). Mp: 168ꢀ170 °C (dec.). 1H
NMR (C6D6): δ 6.77 (m, 6H, aryl), 6.64 (m, 1H, aryl), 6.50 (m, 4H, aryl
and ring CH), 6.21 (d, J = 2.8 Hz, 2H, ring CH), 1.96 (s, 3H, tolylCH3),
1.68 (s, 18H, (CH3)3C), 1.53 (s, 36H, (CH3)3C), 0.42 (s, 9H, (CH3)3Si).
13C{1H} NMR (C6D6): δ 178.7, 148.4, 145.8, 142.9, 140.2, 134.9, 132.4,
130.2, 129.1, 126.9, 125.4, 123.2, 122.4, 112.2, 35.2, 35.1, 35.0, 34.7, 34.0,
32.8, 20.6, 2.80. IR (KBr, cmꢀ1): ν 2961 (s), 1591 (s), 1460 (s), 1357 (s),
1259 (s), 1091 (s), 1016 (s), 798 (s). Anal. Calcd for C51H79N2ClSSiTh:
C, 58.46; H, 7.60; N, 3.38. Found: C, 58.42; H, 7.71; N, 3.35.
X-ray Crystallography. Single-crystal X-ray diffraction measure-
ments were carried out on a Bruker Smart APEX II CCD diffractometer
at 150(2) K using graphite monochromated Mο KR radiation (λ =
0.71070 Å). An empirical absorption correction was applied using the
SADABS program.32 All structures were solved by direct methods and
refined by full-matrix least-squares on F2 using the SHELXL-97 program
package.33 All of the hydrogen atoms were geometrically fixed using the
riding model. The crystal data and experimental data for 6, 7, 10ꢀ14, 16,
17, and 19 are summarized in the Supporting Information. Selected
bond lengths and angles are listed in Table 1.
Computational Methods. All calculations were carried out with
the Gaussian 09 program (G09),34 employing the Becke-3-LeeꢀYangꢀ
Parr (B3LYP) method with standard 6-31G(d) basis set for C, H, O, N,
and S elements and Stuttgart RLC ECP from EMSL basis set exahange
(https://bse.pnl.gov/bse/portal) for Th element,35 to fully optimize the
geometries of reactants, complexes, transition state, intermediates, and
product structures. The self-consistent reaction field (SCRF) polarizable
continuum model (PCM) with default radii in G09 was also used to mimic
experimental toluene-solvent conditions(dielectricconstantε =2.379). All
resultant stationary points were subsequently characterized by vibrational
analyses, from which their respective zero-point (vibrational) energies
(ZPE) were extracted and used in the relative energy determinations, in
addition to ensuring that the reactant, complex, intermediate, product, and
transition state structures resided at minima and first order saddle points,
respectively, on their potential energy hypersurfaces.
’ REFERENCES
(1) For selected recent reviews, see: (a) Ephritikhine, M. Dalton
Trans. 2006, 2501–2516. (b) Szabo, Z.; Toraishi, T.; Vallet, V.;
Grenthe, I. Coord. Chem. Rev. 2006, 250, 784–815. (c) Van Horn,
J. D.; Huang, H. Coord. Chem. Rev. 2006, 250, 765–775. (d) Sessler,
J. L.; Melfi, P. J.; Pantos, D. G. Coord. Chem. Rev. 2006, 250, 816–843.
(e) Barnea, E.; Eisen, M. S. Coord. Chem. Rev. 2006, 250, 855–899. (f)
Fox, A. R.; Bart, S. C.; Meyer, K.; Cummins, C. C. Nature 2008,
455, 341–349. (g) Andrea, T.; Eisen, M. S. Chem. Soc. Rev. 2008,
37, 550–567. (h) Graves, C. R.; Kiplinger, J. L. Chem. Commun.
2009, 3831–3853. (i) Arnold, P. L.; Love, J. B.; Patel, D. Coord. Chem.
Rev. 2009, 253, 1973–1978. (j) Hayton, T. W. Dalton Trans. 2010,
39, 1145–1158. (k) Fortier, S.; Hayton, T. W. Coord. Chem. Rev.
2010, 254, 197–214. (l) Arnold, P. L. Chem. Commun. 2011, DOI:
10.1039/c1cc10834d.
(2) For selected papers on uranium nonmetallocenes containing
terminal oxo groups, see: (a) Andersen, R. A. Inorg. Chem. 1979,
18, 1507–1509. (b) Docrat, T. I.; Mosselmans, J. F. W.; Charnock,
J. M.; Whiteley, M. W.; Collison, D.; Livens, F. R.; Jones, C.; Edmiston,
M. J. Inorg. Chem. 1999, 38, 1879–1882. (c) Duval, P. B.; Burns, C. J.;
Buschmann, W. E.; Clark, D. L.; Morris, D. E.; Scott, B. L. Inorg. Chem.
2001, 40, 5491–5496. (d) Duval, P. B.; Burns, C. J.; Clark, D. L.; Morris,
D. E.; Scott, B. L.; Thompson, J. D.; Werkema, E. L.; Jia, L.; Andersen,
R. A. Angew. Chem., Int. Ed. 2001, 40, 3358–3361. (e) Roussel, P.;
Boaretto, R.; Kingsley, A. J.; Alcock, N. W.; Scott, P. J. Chem. Soc., Dalton
Trans. 2002, 1423–1428. (f) Berthet, J.-C.; Nierlich, M.; Ephritikhine,
M. Angew. Chem., Int. Ed. 2003, 42, 1952–1954. (g) Burdet, F.; Pecaut, J.;
Mazzanti, M. J. Am. Chem. Soc. 2006, 128, 16512–16513. (h) Berthet,
J.-C.; Siffredi, G.; Thuery, P.; Ephritikhine, M. Chem. Commun.
2006, 3184–3186. (i) Natrajan, L.; Burdet, F.; Pecaut, J.; Mazzanti, M.
J. Am. Chem. Soc. 2006, 128, 7152–7153. (j) Hayton, T. W.; Boncella,
J. M.;Scott, B. L.;Batista, E. R. J. Am. Chem. Soc. 2006, 128, 12622–12623.
(k) Hayton, T. W.; Wu, G. J. Am. Chem. Soc. 2008, 130, 2005–2014. (l)
Arnold, P. L.;Patel, D.; Wilson, C.;Love, J. B. Nature 2008, 451, 315–317.
(m) Hayton, T. W.; Wu, G. Inorg. Chem. 2008, 47, 7415–7423. (n) Bart,
S. C.; Anthon, C.; Heinemann, F. W.; Bill, E.; Edelstein, N. M.; Meyer, K.
J. Am. Chem. Soc. 2008, 130, 12536–12546. (o) Nocton, G.; Horeglad, P.;
Pecaut, J.; Mazzanti, M. J. Am. Chem. Soc. 2008, 130, 16633–16645. (p)
Hayton, T. W.; Wu, G. Inorg. Chem. 2009, 48, 3065–3072. (q) Berthet,
J.-C.; Siffredi, G.; Thuery, P.; Ephritikhine, M. Dalton Trans.
2009, 3478–3494. (r) Cantat, T.; Graves, C. R.; Scott, B. L.; Kiplinger,
J. L. Angew. Chem., Int. Ed. 2009, 48, 3681–3684. (s) Horeglad, P.;
Nocton, G.; Filinchuk, Y.; Pꢀecaut, J.; Mazzanti, M. Chem. Commun.
2009, 1843–1845. (t) Fortier, S.; Wu, G.; Hayton, T. W. J. Am. Chem. Soc.
2010, 132, 6888–6889. (u) Kraft, S. J.; Walensky, J.; Franwick, P. E.; Hall,
M. B.; Bart, S. C. Inorg. Chem. 2010, 49, 7620–7622. (v) Brow, J. L.; Wu,
G.; Hayton, T. W. J. Am. Chem. Soc. 2010, 132, 7248–7249. (w)
Tourneux, J.-C.; Berthet, J.-C.; Cantat, T.; Thuꢀery, P.; Mꢀezailles, N.;
Ephritikhine, M. J. Am. Chem. Soc. 2011, 133, 6162–6165. (x) Schnaars,
D. D.; Wu, G.; Hayton, T. W. Inorg. Chem. 2011, 50, 4695–4697. (y)
Brown, J. L.; Mokhtarzadeh, C. C.; Lever, J. M.; Wu, G.; Hayton, T. W.
Inorg. Chem. 2011, 50, 5105–5112.
’ ASSOCIATED CONTENT
S
Supporting Information. Complete list of authors for ref
b
34. Crystal parameters for compounds 6, 7, 10ꢀ14, 16, 17, and
19. ORTEP diagrams of 11, 14, and 16. Cartesian coordinates of
all stationary points optimized at the B3LYP/genecp level and
imaginary frequencies of transition states. H and 13C NMR
1
spectra of new compounds. X-ray crystallographic data, in CIF
format, for compounds 6, 7, 10ꢀ14, 16, 17, and 19. This material
is available free of charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
(3) For selected papers about uranium metallocenes containing
terminal oxo groups, see: (a) Villiers, C.; Adam, R.; Ephritikhine, M.
Chem. Commun. 1992, 1555–1556. (b) Arney, D. S. J.; Burns, C. J. J. Am.
Corresponding Author
gzi@bnu.edu.cn; dcfang@bnu.edu.cn; mwalter@tu-bs.de
13195
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Journal of the American Chemical Society
ARTICLE
Chem. Soc. 1993, 115, 9840–9841. (c) Arney, D. S. J.; Burns, C. J. J. Am.
Chem. Soc. 1995, 117, 9448–9460. (d) Evans, W. J.; Kozimor, S. A.;
Ziller, J. W. Polyhedron 2004, 23, 2689–2694. (e) Zi, G.; Jia, L.;
Werkema, E. L.; Walter, M. D.; Gottfriedsen, J. P.; Andersen, R. A.
Organometallics 2005, 24, 4251–4262.
[(C5Me4R)2U(μ-N)U(μ-N3)(C5Me4R)2]4 (R = H, Me); for details, see:
Evans, W. J.; Kozimor, S. A.; Ziller, J. W. Science 2005, 309, 1835–1838.
(27) Blake, P. C.; Lappert, M. F.; Taylor, R. G.; Atwood, J. L.;
Hunter, W. E.; Zhang, H. J. Chem. Soc., Dalton Trans. 1995, 3335–3341.
(28) Weber, F.; Sitzmann, H.; Schultz, M.; Sofield, C. D.; Andersen,
R. A. Organometallics 2002, 21, 3139–3146.
(29) Edwards, P. G.; Weydert, M.; Petrie, M. A.; Andersen, R. A.
J. Alloys Compd. 1994, 213/214, 11–14.
(30) Zhang, X.; Jiang, X.; Zhang, K.; Mao, L.; Luo, J.; Chi, C.; Chan,
H. S. O.; Wu, J. J. Org. Chem. 2010, 75, 8069–8077.
(31) Jamir, L.; Ali, A. R.; Ghosh, H.; Chipem, F. A. S.; Patel, B. K.
Org. Biomol. Chem. 2010, 8, 1674–1678.
(4) Ventelon, L.; Lescop, C.; Arliguie, T.; Leverd, P. C.; Lance, M.;
Nierlich, M.; Ephritikhine, M. Chem. Commun. 1999, 659–660.
(5) Morss, L. R., Edelstein, N. M., Fuger, J., Katz, J. J., Eds. The
Chemistry of the Actinide and Transactinide Elements, 3rd ed.; Springer:
Dordrecht, 2006; Vols. 1ꢀ5.
(6) Hutchings, G. J.; Heneghan, C. S.; Hudson, I. D.; Taylor, S. H.
Nature 1996, 384, 341–343.
(7) Gmelin Handbuch der Anorganischen Chemie, Thorium, Erg€an-
zungsband Teil C1; Springer-Verlag: Berlin, 1978.
(32) Sheldrick, G. M. SADABS, Program for Empirical Absorption
Correction of Area Detector Data; University of G€ottingen: G€ottingen,
Germany, 1996.
(8) For selected papers on oxo and sulfido group
4
metallocenes, see: (a) Polse, J. L.; Andersen, R. A.; Bergman, R. G.
J. Am. Chem. Soc. 1995, 117, 5393–5394. (b) Carney, M. J.; Walsh, P. J.;
Bergman, R. G. J. Am. Chem. Soc. 1990, 112, 6426–6428. (c) Howard,
W. A.; Parkin, G. J. Am. Chem. Soc. 1994, 116, 606–615. (d) Howard,
W. A.; Trnka, T. M.; Waters, M.; Parkin, G. J. Organomet. Chem. 1997,
528, 95–121. (e) Tainturier, G.;Fahim, M.; Trouvꢀe-Bellan, G.;Gautheron,
B. J. Organomet. Chem. 1989, 376, 321–332. (f) Sweeney, Z. K.; Polse,
J. L.; Andersen, R. A.; Bergman, R. G. J. Am. Chem. Soc. 1998, 120,
7825–7834.
(33) Sheldrick, G. M. SHELXL-97, Program for the Refinement of
Crystal Structure from Diffraction Data; University of G€ottingen:
G€ottingen, Germany, 1997.
(34) Frisch, M. J.; et al. Gaussian 09, revision A.02; Gaussian, Inc.:
Wallingford, CT, 2009.
(35) Kuechle, W.; Dolg, M.; Stoll, H.; Preuss, H. Mol. Phys. 1991,
74, 1245–1263.
(9) Parkin, G. Prog. Inorg. Chem. 1998, 47, 1–165.
(10) Selected recent papers about the bonding of organoactinide
complexes, see: (a) Cantat, T.; Graves, C. R.; Jantunen, K. C.; Burns,
C. J.; Scott, B. L.; Schelter, E. J.; Morris, D. E.; Hay, P. J.; Kiplinger, J. L.
J. Am. Chem. Soc. 2008, 130, 17537–17551. (b) Barros, N.; Maynau, D.;
Maron, L.; Eisenstein, O.; Zi, G.; Andersen, R. A. Organometallics 2007,
26, 5059–5065. (c) Yahia, A.; Maron, L. Organometallics 2009,
28, 672–679.
(11) Lukens, W. W., Jr.; Beshouri, S. M.; Blosch, L. L.; Andersen,
R. A. J. Am. Chem. Soc. 1996, 118, 901–902.
(12) For the ionic radius of thorium (Th4+ = 1.08 Å) and uranium
(U4+ = 1.03 Å), see:Cotton, F. A.; Wilkinson, G.; Murillo, C. A.;
Bochmann, M. Advanced Inorganic Chemistry, 6th ed.; John Wiley &
Sons: New York, 1999; p 1131.
(13) 5f orbitals play a key role in the bonding in actinide complexes,
which leads to a very polarized MdE bond, whereas this does not occur
for a group 4 metal complex.10c For example, the MdO is a single bond
with an electrostatic interaction for actinide metals (i.e., M+ꢀOꢀ), while
it is a double bond for group 4 metals.10b,c
(14) Bagnall, K. W. The Actinide Elements; Elsevier: Amsterdam,
1972.
(15) Nugent, W. A.; Mayer, J. M. Metal Ligand Multiple Bonds;
Wiley-Interscience: New York, 1988.
(16) Guymont, M.; Livage, J.; Maziꢁeres, C. Bull. Soc. Fr. Mineral.
Cristallogr. 1973, 96, 161–165.
(17) Haskel, A.; Straub, T.; Eisen, M. S. Organometallics 1996, 15,
3773–3775.
(18) Berg, J. M.; Clark, D. L.; Huffman, J. C.; Morris, D. E.;
Sattelberger, A. P.; Streib, W. E.; Van Der Sluys, W. G.; Watkin, J. G.
J. Am. Chem. Soc. 1992, 114, 10811–10821.
(19) Clark, D. L.; Watkin, J. G. Inorg. Chem. 1993, 32, 1766–1772.
(20) Lam, O. P.; Heinemann, F. W.; Meyer, K. Chem. Sci. 2011,
2, 1538ꢀ1547.
(21) Shein, K. I.; Shein, I. R.; Medvedeva, N. I.; Bamburov, V. G.;
Ivanovskii, A. L. Dokl. Phys. Chem. 2006, 409, 198–201.
(22) Wrobleski, D. A.; Cromer, D. T.; Ortiz, J. V.; Rauchfuss, T. B.;
Ryan, R. R.; Sattelberger, A. P. J. Am. Chem. Soc. 1986, 108, 174–175.
(23) Eastman, E. D.; Brewer, L.; Bromley, L. R. A.; Gilles, P. W.;
Lofgren, N. L. J. Am. Chem. Soc. 1950, 72, 4019–4023.
(24) Shannon, R. D. Acta Crystallogr., Sect. A 1976, 32, 751–767.
(25) Zachariasen, W. H. Acta Crystallogr. 1949, 2, 291–296.
(26) This term has been used by Evans and his co-workers to
describe their alternating nitride and azide bridged uranium clusters
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dx.doi.org/10.1021/ja205280k |J. Am. Chem. Soc. 2011, 133, 13183–13196