Uranium versus Thorium: Synthesis and Reactivity of [η5-1,2,4-(Me3C)3C5H2]2U[η2-C2Ph2]

Article abstract of DOI:10.1002/chem.202100089

The synthesis, electronic structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Addition of diphenylacetylene (PhC≡CPh) to the uranium phosphinidene metallocene [η⁵-1,2,4-(Me₃C)₃C₅H₂]₂U=P-2,4,6-tBu₃C₆H₂ (1) yields the stable uranium metallacyclopropene, [η⁵-1,2,4-(Me₃C)₃C₅H₂]₂U[η²-C₂Ph₂] (2). Based on density functional theory (DFT) results the 5f orbital contributions to the bonding within the metallacyclopropene U-(η²-C=C) moiety increases significantly compared to the related Th^IV compound [η⁵-1,2,4-(Me₃C)₃C₅H₂]₂Th[η²-C₂Ph₂], which also results in more covalent bonds between the [η⁵-1,2,4-(Me₃C)₃C₅H₂]₂U²⁺ and [η²-C₂Ph₂]^2? fragments. Although the thorium and uranium complexes are structurally closely related, different reaction patterns are therefore observed. For example, 2 reacts as a masked synthon for the low-valent uranium(II) metallocene [η⁵-1,2,4-(Me₃C)₃C₅H₂]₂U^II when reacted with Ph₂E₂ (E=S, Se), alkynes and a variety of hetero-unsaturated molecules such as imines, ketazine, bipy, nitriles, organic azides, and azo derivatives. In contrast, five-membered metallaheterocycles are accessible when 2 is treated with isothiocyanate, aldehydes, and ketones.

Full text of DOI:10.1002/chem.202100089

Full Paper
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&
Organometallic Chemistry
Uranium versus Thorium: Synthesis and Reactivity of
5
2
[
h -1,2,4-(Me C) C H ] U[h -C Ph ]
3
3 5 2 2
2
2
[a]
[a]
[a]
[a]
[b]
Deqiang Wang, Wanjian Ding, Guohua Hou, Guofu Zi,* and Marc D. Walter*
5
2+
2
2À
2
Abstract: The synthesis, electronic structure, and reactivity
of a uranium metallacyclopropene were comprehensively
studied. Addition of diphenylacetylene (PhCꢀCPh) to
the [h -1,2,4-(Me C) C H ] U and [h -C Ph ] fragments. Al-
3 3 5 2 2 2
though the thorium and uranium complexes are structurally
closely related, different reaction patterns are therefore ob-
served. For example, 2 reacts as a masked synthon for the
5
the uranium phosphinidene metallocene [h -1,2,4-
5
II
(
Me C) C H ] U=P-2,4,6-tBu C H (1) yields the stable uranium
low-valent uranium(II) metallocene [h -1,2,4-(Me C) C H ] U
3 3 5 2 2
3
3
5
2 2
3
6
2
5
2
metallacyclopropene, [h -1,2,4-(Me C) C H ] U[h -C Ph ] (2).
when reacted with Ph E (E=S, Se), alkynes and a variety of
2 2
3
3
5
2 2
2
2
Based on density functional theory (DFT) results the 5f orbi-
tal contributions to the bonding within the metallacyclopro-
hetero-unsaturated molecules such as imines, ketazine, bipy,
nitriles, organic azides, and azo derivatives. In contrast, five-
membered metallaheterocycles are accessible when 2 is
treated with isothiocyanate, aldehydes, and ketones.
2
pene U-(h -C=C) moiety increases significantly compared to
IV
5
2
the related Th compound [h -1,2,4-(Me C) C H ] Th[h -
3
3
5
2 2
C Ph ], which also results in more covalent bonds between
2
2
[
3]
Introduction
ty. These studies should be considered in the context of cur-
rent developments in the actinide field focusing on small mol-
[
4]
Metallacyclopropenes, especially those of d-transition metals,
ecule activation and the impact of 5f orbital contributions on
[
1]
[5]
have been extensively studied for the last three decades.
bonding and the reactivity.
Within this class of compounds group 4 metallacyclopropenes
We have been interested in thorium and uranium metallacy-
[
6]
bearing a Cp’ M fragment (where Cp’=substituted or unsub-
cles for some time, which we recently documented with the
2
5
5
stituted h -cyclopentadienyl) are probably the most thoroughly
synthesis of two stable actinide metallacyclopropenes [h -1,2,4-
2
[6a]
5
2
[6f]
investigated class. In the presence of a suitable unsaturated
(Me C) C H ] Th(h -C Ph )
and (h -C Me ) U[h -C (SiMe ) ].
5 5 2 2 3 2
3
3
5
2 2
2
2
5
substrate, the coordinated alkyne is readily displaced releasing
The alkyne in the thorium metallacyclopropene [h -1,2,4-
II
2
a Cp’ M fragment which reacts with the provided substrate to
(Me C) C H ] Th(h -C Ph ) reacts as a nucleophile towards
2
3
3
5
2 2
2
2
yield highly functionalized organic molecules or heterocyclic
hetero-unsaturated molecules such as aldehydes, ketones, CS2,
carbodiimides, nitriles, isothiocyanates, organic azides, and di-
[1,2]
main group element compounds.
The reactivity of these
group 4 metallacyclopropenes varies with the steric and elec-
azoalkane derivatives or as a strong base inducing intermolec-
[
1,2]
[6a,b]
tronic properties exerted by the Cp’ and alkyne ligands.
In
ular CÀH bond activation.
In contrast, the uranium metalla-
5
2
contrast to this well-established chemistry of group 4 metals,
metallacycles of the lanthanides and actinides have only re-
cently attracted renewed attention after many years of inactivi-
cyclopropene (h -C Me ) U[h -C (SiMe ) ] acts as a masked syn-
5
5 2
2
3 2
5
thon for the (h -C Me ) U(II) fragment when reacted with unsa-
5
5 2
6f,g]
[
turated molecules.
Unfortunately, at the time we could not
5
2
directly compare [h -1,2,4-(Me C) C H ] Th(h -C Ph ) to its
3
3
5
2 2
2
2
5
2
uranium analogue [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2), so
3
3
5
2 2
2
2
[
a] D. Wang, Dr. W. Ding, Dr. G. Hou, Prof. G. Zi
Department of Chemistry, Beijing Normal University, Beijing 100875 (China)
E-mail: gzi@bnu.edu.cn
5
that some of the differences observed for [h -1,2,4-
2
5
2
(Me C) C H ] Th(h -C Ph ) and (h -C Me ) U[h -C (SiMe ) ] may
3
3
5
2 2
2
2
5
5 2
2
3 2
[
b] Prof. Dr. M. D. Walter
also be traced to the different steric requirements of the coor-
dinated ligands. Only recently, we could serendipitously isolate
Institut für Anorganische und Analytische Chemie
Technische Universität Braunschweig, Hagenring 30
5
2
the missing uranium counterpart [h -1,2,4-(Me C) C H ] U(h -
3
3
5
2 2
5
3
8106 Braunschweig (Germany)
C Ph ) (2), while studying the reactivity of [h -1,2,4-
E-mail: mwalter@tu-bs.de
2
2
[
7]
(
Me C) C H ] U=P-2,4,6-tBu C H (1). This now allowed us to
3 3 5 2 2 3 6 2
Supporting information and the ORCID identification number(s) for the
author(s) of this article can be found under:
https://doi.org/10.1002/chem.202100089.
directly evaluate both actinide metallacyclopropenes and to
establish differences and similarities in the reactivity of these
compounds. These results are described in this manuscript.
ꢀ
2021 The Authors. Chemistry - A European Journal published by Wiley-
VCH GmbH. This is an open access article under the terms of the Creative
Commons Attribution Non-Commercial License, which permits use, distribu-
tion and reproduction in any medium, provided the original work is proper-
ly cited and is not used for commercial purposes.
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[
6a]
(
1.331 Š)
and is essentially identical to those found in
Results and Discussion
5
2
the uranium metallacyclopropene (h -C Me ) U[h -C (SiMe ) ]
5
5 2
2
3 2
[
6f]
5
(
(
1.338(11) Š) and the thorium metallacyclopropenes [h -1,2,4-
5
2
Synthesis of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2)
3
3
5
2 2
2
2
2
[6a]
5
2
Me C) C H ] Th(h -C Ph ) (1.343(4) Š) and [(h -C Me ) Th(h -
3
3
5
2 2
2
2
5
5 2
[
6e]
Heating a mixture of the uranium phosphinidene metallocene
C Ph(SiMe ))(Cl)][Li{MeO(CH CH O) Me} ] (1.360(7) Š), indicat-
2 3 2 2 2 2
5
2
2À
[
h -1,2,4-(Me C) C H ] U=P-2,4,6-tBu C H (1) with PhCꢀCPh in
ing a doubly reduced alkyne ligand, [h -C Ph ] . The angle
2
3
3
5
2 2
3
6
2
2
toluene at 508C forms the air and moisture sensitive metallacy-
clopropene, [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2), which can be
(33.2(6)8) of C(41)-U(1)-C(42) also parallels that in the uranium
metallacyclopropene (h -C Me ) U[h -C (SiMe ) ] (33.3(3)8)
5 5 2 2 3 2
5
2
5
2
[6f]
3
3
5
2 2
2
2
isolated as brown crystals in 80% yield, while the phosphain-
and the C-Th-C angle (32.6(1)8) in the related thorium metalla-
5
2
[6a]
dane 3,3-Me -5,7-tBu C H P is formed as the side-product
cyclopropene [h -1,2,4-(Me C) C H ] Th(h -C Ph ).
Further-
2
2
8
5
3
3
5
2 2
2
2
[
7]
(
Scheme 1). Complex 2 is very soluble in and readily recrystal-
more, the angles of C(41)-C(42)-C(43) (127(2)8) and C(40)-C(41)-
C(42) (130(2)8) approach a value of 1208, which is the expecta-
lized from an n-hexane solution. The molecular structure of 2
is shown in Figure 1, and selected bond lengths and angles are
listed in Table 1. The relevant C(41)ÀC(42) distance of 1.33(2) Š
agrees with the value found for a typical double bond
2
tion value for sp -hybridized carbon atoms. The UÀC distances
are 2.35(2) Š for C(41) and 2.298 (19) Š for C(42), which are
5
similar but slightly more asymmetric than those in (h -
2
[6f]
C Me ) U[h -C (SiMe ) ] (2.315(9) and 2.350(9) Š). For compar-
5
5 2
2
3 2
ison the ThÀC distance in the thorium metallacyclopropene
h -1,2,4-(Me C) C H ] Th(h -C Ph ) is 2.395 (2) Š, which is
5
2
[6a]
[
3
3
5
2 2
2
2
IV
longer than expected based on the different ionic radii of Th
IV
[8]
(
1.05 Š) and U (1.00 Š) (with a coordination number of 8).
Nevertheless, in contrast to the formation of the thorium
5
2
[6a]
metallacyclopropene [h -1,2,4-(Me C) C H ] Th(h -C Ph ),
the
3
3
5
2 2
2
2
5
reduction of [h -1,2,4-(Me C) C H ] UCl (3) in the presence of
3
3
5
2 2
2
an excess of potassium graphite (KC ) and diphenylacetylene
8
(
PhCꢀCPh) does not cleanly yield the desired uranium metalla-
cyclopropene 2, but a mixture of the uranium metallacyclopro-
pene
5
2 and the uranium(III) chloride species [h -1,2,4-
[
9]
(
Me C) C H ] UCl (4) is formed (Scheme 2), which can be ex-
3
3
5
2 2
IV
III
8
plained by the moderate reduction potential of U /U (E =
[
10]
À0.63 V). The ratio of 2 and 4 is roughly 1:3 (as confirmed
1
by H NMR spectroscopy). Unfortunately, this mixture cannot
be converted to pure 2 upon prolonged reduction with excess
potassium graphite (KC ) in the presence of diphenylacetylene.
8
Furthermore, attributed to a remarkably similar solubility the
mixture of complexes 2 and 4 could not be separated by re-
crystallization.
Scheme 1. Synthesis of complex 2.
Figure 1. Molecular structure of 2 (thermal ellipsoids drawn at the 35%
probability level).
Scheme 2. Synthesis of complexes 2 and 4.
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[a]
Table 1. Selected distances (Š) and angles (deg) for compounds 2, 5, 9, 10, 12, 14, 16–18 and 20–23.
[
b]
[c]
[b]
Compound
C(Cp)ÀU
C(Cp)ÀU
Cp(cent)ÀU
UÀX
Cp(cent)-U-Cp(cent)
X-U-X/Y
2
2
5
2.79(2)
2.861(2)
2.803(5)
2.71(2) to 2.890(18)
2.798(2) to 2.950(2)
2.746(5) to 2.855(5)
2.51(2)
2.592(2)
2.528(5)
C(41) 2.35(2), C(42) 2.298(19)
Th-C 2.395(2), 2.395
141.2(6)
138.7(2)
139.4(2)
33.2(6)
32.6(1)
92.4(2)
[6a]
’ (Th)
[d]
C(41) 2.475(5), C(42) 2.449(5)
C(43) 2.448(5), C(44) 2.463(5)
N(1) 2.222(2), N(2) 2.214(2)
N(1) 2.252(5), N(1A) 2.252(5)
N(1) 2.208(4), C(35) 2.482(6)
N(1) 1.977(3), N(2) 1.974(3)
N(1) 1.968(4)
9
1
1
1
1
1
2.798(3)
2.817(5)
2.818(5)
2.806(3)
2.841(5)
2.787(5)
2.737(3) to 2.873(3)
2.731(6) to 2.927(6)
2.748(5) to 2.914(5)
2.749(3) to 2.888(3)
2.729(5) to 2.976(5)
2.725(5) to 2.846(5)
2.523(3)
2.544(6)
2.546(5)
2.532(2)
2.570(5)
2.511(5)
149.2(1)
144.3(2)
136.4(2)
139.2(1)
134.1(3)
140.4(2)
72.3(1)
70.9(3)
69.3(2)
98.7(1)
0
2
4
6
7
[e]
N(1) 2.227(4), N(2) 2.418(4)
C(39) 2.517(6)
33.4(2)
1
2
2
2
2
8
0
1
2
3
2.804(5)
2.709(5) to 2.931(4)
2.699(10) to 2.895(10)
2.731(3) to 2.962(3)
2.726(3) to 2.953(4)
2.735(5) to 2.916(5)
2.530(5)
2.522(10)
2.557(3)
2.546(4)
2.562(5)
S(1) 2.659(1), S(2) 2.628(1)
S(1) 2.649(2), C(37) 2.480(10)
O(1) 2.062(2), C(37) 2.581(3)
O(1) 2.069(2), C(43) 2.577(4)
O(1) 2.076(4), C(35) 2.572(6)
142.5(1)
140.9(2)
133.6(1)
133.8(1)
126.7(2)
100.4(1)
76.0(2)
67.6(1)
67.5(1)
67.1(2)
2.795(10)
2.828(3)
2.817(4)
2.833(5)
[
a] Cp=cyclopentadienyl ring. [b] Average value. [c] Range. [d] The angle of C(41)-U(1)-C(44). [e] The angle of N(1)-U(1)-N(2).
Bonding studies
nium hybrid orbital (22.2%; 40.9% 5f and 54.2%). In addition,
two bonding orbitals are identified for the CÀC bond: the s-
bond (s(C=C)) composes of two carbon hybrid orbitals (47.7%;
29.0% s and 71.0% p; and 47.7%; 28.9% s and 71.1% p),
whereas the p-bond (p[U(C=C)]) is made up by 84.6% carbon
occupancy consisting of only p orbitals and a 11.7% contribu-
tion from a uranium hybrid orbital (48.5% 5f and 50.6% 6d).
These results implicate that electron density is also shifted
from the alkyne p-orbital to the electron deficient metal urani-
Density functional theory (DFT) computations at the B3PW91
level of theory were performed to probe the interaction be-
5
2+
2
2À
tween the [h -1,2,4-(Me C) C H ] U and the [h -C Ph ] frag-
3
3
5
2 2
2
2
ments, which also allows the bonding in 2 to be compared to
its thorium analogue [h -1,2,4-(Me C) C H ] Th(h -C Ph ) (2’).
Computed and experimentally determined molecular structure
5
2
3
3
5
2 2
2
2
of 2 are in good agreement and reproduce the asymmetry
2
within the An[h -C Ph ] metallacyclopropene moiety with two
um atom.
2
2
5
in-plane AnÀC s-bonds and one out-of-plane p-bond interact-
ing with the metal center, as illustrated in Figure 2. The natural
localized molecular orbital (NLMO) analysis (Table 2) suggests
However,
in
the
thorium
counterpart
[h -1,2,4-
2
(Me C) C H ] Th(h -C Ph ) (2’), the metal contribution to the
3
3
5
2 2
2
2
2
bonding of the Th(h -C Ph ) moiety is significantly reduced
2
2
that s (UÀC) bond combines a carbon hybrid orbital (72.9.0%;
(16.0% and 16.1%% Th for ThÀC s and s bond, respectively,
1
1
2
2
4
5.7% s and 74.3% p) and a uranium hybrid orbital (22.0%;
and 8.4% Th for Th-(C=C) p bond) (Table 2). An increased
1.1% 5f and 54.0% 6d), whereas s (UÀC) bond is formed by a
charge separation result, which increases the electrostatic in-
2
5
2+
carbon hybrid orbital (72.9%; 25.7% s and 74.3% p) and a ura-
teraction between the individual [h -1,2,4-(Me C) C H ] An
3 3 5 2 2
2
2À
and [h -C Ph ] fragments, that is, 1.56 for U (2) and 2.12 for
2
2
Th (2’) (Table 2). Furthermore, the Wiberg bond order of the
An-C Ph is reduced from 0.801 and 0.804 (for 2) to 0.678 and
2
2
0
.681 (for 2’)) (Table 2). Both observations reflect the increased
polarization and ionicity within the bonding between the met-
5
2+
2
2À
2
allocene [h -1,2,4-(Me C) C H ] Th and the alkyne [h -C Ph ]
3
3
5
2 2
2
fragments. Also the p-donation from the p-MO of the coordi-
nated alkyne to the metal atom is significantly less efficient,
which is due to an increase in the 5f orbital energy of the tho-
[
5g,h]
rium atom relative to that of the uranium atom.
ation of the 5f orbital contribution to the U-C s (41.1% and
0.9%% for s1 and s2 bond, respectively) and U-(C=C) p
48.5%) bonds in 2 reveals it to be substantially larger than
The evalu-
4
(
that of the 5f orbitals in 2’ (16.7% and 16.6% for ThÀC s and
1
s bond, respectively, and 31.2% for Th-(C=C) p bond), which
2
[
5d,f,6c,f,i]
is in line with the previously investigated systems.
Over-
all, this difference should also manifest itself in divergent reac-
tivities of the uranium complex 2 relative to that of the thori-
[
6a,b,11]
um metallacyclopropenes.
Figure 2. Plots of HOMOs for 2 (hydrogen atoms have been omitted for
clarity).
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Table 2. Natural localized molecular orbital (NLMO) analysis of AnÀ
[
a]
5
(
(
C
2
Ph
2
) bonds, bond order, and the natural charges for the [h -1,2,4-
2
Me C) C H ] An and [h -C Ph ] units.
3 5 2 2 2 2
3
2
(U)
2’ (Th)
s
1
AnÀC
%An
22.0
3.6
1.3
54.0
41.1
16.0
5.1
1.9
76.3
16.7
%
%
%
%
s
p
d
f
%
%
%
C
s
p
72.9
25.7
74.3
79.0
25.6
74.6
s
2
AnÀC
%An
22.2
3.6
1.3
54.2
40.9
16.1
5.0
1.8
76.6
16.6
%
%
%
%
s
p
d
f
%
%
%
C
s
p
72.9
25.7
74.3
79.0
25.4
74.6
s C=C
%An
3.0
2.9
%
%
%
%
s
1.8
3.3
44.0
50.9
2.7
3.5
51.1
42.7
p
d
f
5
2
3 3 5 2 2 2 2
Figure 3. Selected reactivity of [h -1,2,4-(Me C) C H ] Th(h -C Ph ) (2’).
%
%
%
C
s
p
47.7
29.0
71.0
47.9
31.6
68.4
5
In accordance with the thorium metallacyclopropene [h -
2
[6a]
1
,2,4-(Me C) C H ] Th(h -C Ph ), no alkyne dissociation could
3 3 5 2 2 2 2
be detected by NMR spectroscopy within the temperature
%
%
%
C
s
p
47.7
28.9
71.1
47.9
31.5
68.5
range of 20–1008C. However, contrary to the thorium metalla-
5
2
[6a]
cyclopropene [h -1,2,4-(Me C) C H ] Th(h -C Ph ), the coordi-
3
3
5
2 2
2
2
nated diphenylacetylene ligand in 2 is labile enough to be ex-
changed by internal alkynes. For example, addition of 1,4-di-
phenylbutadiyne (PhCꢀCCꢀCPh) at 408C gives the uranium
p An(C=C)
%An
11.7
0.9
50.6
48.5
8.4
2.1
66.7
31.2
%
%
%
p
d
f
5
4
metallacyclopentatriene complex [h -1,2,4-(Me C) C H ] U(h -
3
3
5
2 2
C Ph ) (5) and diphenylacetylene (PhCꢀCPh) (Scheme 3). To ac-
4
2
%
%
C
p
42.3
100
44.0
100
count for this transformation, it is proposed that diphenylbuta-
diyne replaces diphenylacetylene to give a metallacyclopro-
%
%
C
p
42.3
100
44.1
100
Wiberg bond order (An-C
2
Ph
2
)
0.801
0.678
0.681
1.60
0
.804
NBO charge (An)
1.31
NBO charge (Cp
2
An)
0.78
1.06
NBO charge (C Ph
2
2
)
À0.78
À1.06
[
a] The contributions by atom and orbital are averaged over all the li-
gands of the same type (complexes of U and Th) and over alpha and
beta orbital contributions (complex of U).
Reactivity studies
We then investigated the reactivity of 2 towards a series of or-
ganic substrates and compared the reaction outcomes to
those obtained for the thorium metallacyclopropene complex
5
2
[
h -1,2,4-(Me C) C H ] Th(h -C Ph ) (2’). Figure 3 summarizes the
3 3 5 2 2 2 2
products obtained for 2’.
Scheme 3. Synthesis of complexes 5 and 6.
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pene complex, which converts by a [1,3]-U migration to yield
complex 5 (Scheme 3). The molecular structure of 5 is provided
in Figure 4, and selected bond distances and angles are listed
in Table 1. The CÀC distances of C(41)ÀC(42), C(42)ÀC(43) and
C(43)ÀC(44) are 1.307(7), 1.305(8) and 1.300(7) Š, respectively,
which suggest a delocalized cumulene moiety. The angles of
C(35)-C(41)-C(42) and C(45)-C(44)-C(43) are 127.5(5) and
1
28.3(5)8, respectively, approach the value of 1208, consistent
2
with sp -hybridization at the carbon atoms. Nevertheless, the
cumulene fragment itself remains rather strained with C(41)-
C(42)-C(43) and C(44)-C(43)-C(42) angles of 150.2(5)8 and
1
49.9(5)8, respectively. Similar structural parameters were also
found for the previously reported actinide metallacyclopenta-
5
4
[6d]
[3p]
5
trienes (h -C Me ) An(h -C Ph ) (An=Th,
U
), (h -
5
5 2
4
2
5
4
[6f]
4
[6j]
C Me ) U[h -C (SiMe ) ],
[h -1,3-(Me C) C H ] U(h -C Ph )
5
5 2
5
4
3 2
4
3
2
5
3 2
4
2
[6h]
and (h -C Me ) Th[h -C (SiMe ) ].
5
5 2
4
3 2
Diphenylacetylene displacement in 2 is also encountered in
the presence of hetero-unsaturated organic molecules. For ex-
ample, complex 2 reacts with the aldimine PhCH=NPh to yield
Scheme 4. Synthesis of complexes 7 and 8.
5
2
the metallaaziridine [h -1,2,4-(Me C) C H ] U(h -CHPhNPh) (6)
3
3
5
2 2
(
Scheme 3). Nevertheless, treatment of 2 with the hydrazine
5
derivative (Ph C=N) yields the bisiminato complex [h -1,2,4-
2
2
(
(
Me C) C H ] U(N=CPh )
(7)
and
diphenylacetylene
3
3
5
2 2
2 2
Scheme 4). Like in the reaction with PhCH=NPh, presumably
diphenylacetylene replacement with (Ph C=N) furnishes a
2
2
metallaaziridine, which converts by NÀN bond cleavage to 7
Scheme 4). Moreover, it is of note that the uranium bipy com-
(
5
[9]
plex [h -1,2,4-(Me C) C H ] U(bipy) (8) can also be accessed
3
3
5
2 2
by the addition of 2,2’-bipyridine (bipy) to 2 (Scheme 4).
Diphenylacetylene substitution is also encountered in
the reaction of 2 with the nitriles RCN (R=C H , Ph CH),
6
11
2
5
in which five-membered metallaheterocycles [h -1,2,4-
(
(
Me C) C H ] U[(N=CR) ] (R=C H (9), Ph CH (10)) are formed
3 3 5 2 2 2 6 11 2
Scheme 5). Again, in analogy to the reaction with PhCH=NPh,
RCN may initially replace the diphenylacetylene ligand to give
2
[6g]
a h -coordinated nitrile intermediate,
which spontaneously
incorporates a second molecule of RCN to give the five-mem-
bered heterometallacycles 9–10 (Scheme 5). The molecular
Scheme 5. Synthesis of complexes 9–12.
structure of 9 is shown in Figure 5, whereas the structure of 10
is provided in the Supporting Information. The UÀN distances
are 2.222(2) and 2.214(2) Š for 9, and 2.252(5) Š for 10, and the
N-U-N angles are 72.3(1)8 for 9 and 70.9(3)8 for 10. Neverthe-
less, when the slightly less sterically encumbered PhCN is used,
only the insertion of 1 equiv of PhCN into the uranium metalla-
cyclopropene moiety of 2 occurs at room temperature to
Figure 4. Molecular structure of 5 (thermal ellipsoids drawn at the 35%
probability level).
5
yield the five-membered heterocyclic complex [h -1,2,4-
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Figure 5. Molecular structure of 9 (thermal ellipsoids drawn at the 35%
probability level).
Scheme 6. Synthesis of complexes 13 and 14.
(
(
Me C) C H ] U[N=C(Ph)(C Ph )] (11) in quantitative conversion
PhCH=NPh, RN=NR replaces the diphenylacetylene fragment
to form a three-membered metallacyclic intermediate, which
transforms by electron transfer and NN bond cleavage to yield
the bisimido products 13–14 (Scheme 6). The molecular struc-
ture of 14 is shown in Figure 7, and the selected bond distan-
ces and angles are listed in Table 1. The short UÀN distances
(1.977(3) Š for N(1) and 1.974(3) Š for N(2)) and the angles of
U-N(1)-C(35) (168.4(2) and U-N(2)-C(42) (173.0(3)8) are consis-
3
3
5
2 2
2
2
Scheme 5). A similar reaction was also observed for the thori-
5
2
um metallacyclopropene [h -1,2,4-(Me C) C H ] Th(h -C Ph )
3
3
5
2 2
2
2
[6a]
with PhCN (Figure 3). However, when benzyl nitrile PhCH CN
2
5
is added to 2 the five-membered heterocyclic complex [h -
1
,2,4-(Me C) C H ] U[NHC(=CHPh)(C Ph )] (12) formed in quan-
3 3 5 2 2 2 2
titative conversion (Scheme 5). We assume that 2 initially
reacts with PhCH CN to give a five-membered heterocyclic in-
2
[
12]
termediate (analogous to compound 11), which converts by
[
tent with a U=N double bond. These structural parameters
5
1,3]-H migration to yield the final product 12 (Scheme 5).
may be compared to those found in [h -1,2,4-(Me C) C H ] U(=
3
3
5
2 2
Figure 6 illustrates the molecular structure of 12 and selected
NPh) (13) with the UÀN distances of 1.985(4) and 1.981(4) Š
2
[
7]
5
bond lengths and angles are collected in Table 1. The C(37)À and the U-N-C angles of 171.4(4) and 172.8(4)8,
(h -
C(50) distance is 1.379(8) Š, and C(37)ÀN(1) distance is 1.384(7)
C Me ) U(=N-p-tolyl) with the UÀN distances of 1.971(4) and
5
5 2
2
[6f]
Š
. The UÀN distance is 2.208(4) Š, whereas UÀC(35) distance is
1.975(3) Š and the U-N-C angles of 178.8(3) and 179.1(3)8,
5
2
.482(6) Š, and the angle of N(1)-U-C(35) is 69.3(2)8.
and (h -C Me ) U(=NPh) with the UÀN distance of 1.952(7) Š
5
5 2
2
[13]
However, complex 2 yields with the diazenes RN=NR (R=Ph,
and the U-N-C angle of 177.8(6)8. It is of note that the urani-
5
5
[9]
p-tolyl) the bisimido uranium(VI) complexes [h -1,2,4-
um metallocenes such as [h -1,2,4-(Me C) C H ] U(bipy),
3 3 5 2 2
5
[6k]
5
(
Me C) C H ] U(=NR) (R=Ph (13), p-tolyl (14)) in quantitative
(h -C Me )U(bipy),
[h -1,2,4-(Me C) C H ] U=P-2,4,6-tBu C H
3 3 5 2 2 3 6 2
3
3
5
2 2
2
5
5
[
7]
5
2
[6f,g]
[14]
5
conversion (Scheme 6). Analogously to the reaction with
(1),
(h -C Me ) U{h -C (SiMe ) },
[(C Me ) UH] ,
(h -
5
5 2
2
3 2
5
5 2
2
Figure 6. Molecular structure of 12 (thermal ellipsoids drawn at the 35%
Figure 7. Molecular structure of 14 (thermal ellipsoids drawn at the 35%
probability level).
probability level).
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[
3g,15]
6
6
[16]
5
C Me )U[(m-Ph) BPh ],
[(C Me ) U] (m-h :h -C H ), and (h -
5 5 2 2 6 6
5
5
2
2
[17]
II
C Me )U[P(SiMe )(2,4,6-Me Ph)](THF)
may also act as Cp U
2
5
5
3
3
synthons forming bisimido uranium(VI) complexes.
Moreover, complex 14 may also be formed from the reaction
of 2 with p-tolylN (Scheme 7). This contrasts the transforma-
3
5
tion of the thorium metallacyclopropene [h -1,2,4-
2
[6a]
(
Me C) C H ] Th(h -C Ph ) with organic azides, in which inser-
3 3 5 2 2 2 2
tion or isomerization products were isolated. Instead the reac-
tivity of 2 more closely resembles that observed for the bipy
5
complexes [h -1,2,4-(Me C) C H ] An(bipy) (An=Th, U) towards
3
3
5
2 2
[
9,18]
p-tolylN3.
and releases N2 to give the imido complex [h -1,2,4-
Me C) C H ] U=N(p-tolyl) (15), which reacts with a second
p-TolylN3 displaces the diphenylacetylene in 2
5
(
3
3
5
2 2
molecule of p-tolylN to yield the bisimido uranium(VI) com-
3
pound 14 concomitant with N evolution (Scheme 7).
Figure 8. Molecular structure of 16 (thermal ellipsoids drawn at the 35%
2
Moreover, in analogy to the reactivity of the bipy complex
probability level).
5
[18]
[
h -1,2,4-(Me C) C H ] Th(bipy) towards Ph CN ,
the bulky
3
3
5
2 2
3
3
trityl azide Ph CN displaces the diphenylacetylene in 2 and re-
3
3
5
leases N2 to give the uranium(IV) imido complex [h -1,2,4-
(
(
Me C) C H ] U=NCPh
(16) in quantitative conversion
Scheme 7). The molecular structure of 16 is provided in
3
3
5
2 2
3
Figure 8, while selected bond distances and angles are pre-
sented in Table 1. The short UÀN distance (1.968(4) Š)) and the
angle of U-N(1)-C(35) (169.3(3)8) are consistent with a U=N
[
12]
double bond. These structural parameters may be compared
5
to those found in [h -1,2,4-(Me C) C H ] U=N(p-tolyl) (15) with
3
3
5
2 2
the UÀN distance of 1.988(5) Š and the U-N-C angle of
72.3(5)8.
Moreover, for the reaction of the thorium metallacyclopro-
[
9]
1
5
2
pene [h -1,2,4-(Me C) C H ] Th(h -C Ph ) with 9-diazofluorene
3
3
5
2 2
2
2
[
6a]
(
C H )CN insertion or isomerization products are isolated.
12 8 2
5
This contrasts the uranium(V) imido cyanido [h -1,2,4-
Me C) C H ] U(=NN=CHSiMe )(CN) (17) isolated from the reac-
(
3
3
5
2 2
3
tion of 2 with Me SiCHN (Scheme 8). To rationalize this prod-
3
2
uct formation it is proposed that 2 initially reacts with 2 equiv
of Me SiCHN resulting in diphenylacetylene replacement fol-
3
2
Scheme 8. Synthesis of complex 17.
lowed by electron transfer to yield a uranium(VI) bisimido com-
plex. In the next step, this bisimido complex forms a four-
membered intermediate, which converts via [1,3]-Si migration
to yield a uranium(VI) isonitrile complex, in which the NÀN
bond is homolytically cleaved to yield 17 and the amine radical
Me SiNH·. The latter further dimerizes to the hydrazine deriva-
3
tive (Me SiNH) (Scheme 8). The molecular structure of 17 is
3
2
presented in Figure 9, whereas relevant bond distances and
angles are compiled in Table 1. The UÀN distances are
2
.227(4) Š for N(1) and 2.418(4) Š for N(2), whereas the UÀ
C(39) distance is 2.517(6) Š. The C(39)ÀN(3) distance is
1
.145(8) Š, whereas the C(35)ÀN(2) distance is 1.293(7) Š. The
Scheme 7. Synthesis of complexes 14–16.
Chem. Eur. J. 2021, 27, 6767 – 6782
angle of N(1)-U-N(2) is 33.4(2)8, whereas the linear angle of U-
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Figure 9. Molecular structure of 17 (thermal ellipsoids drawn at the 35%
probability level).
C(39)-N(3) is 176.6(5)8. The N(1)ÀN(2) distance is 1.348(7) Š,
and the N(2)ÀC(35) distance is 1.293(7) Š.
Furthermore, replacement of the coordinated diphenylacety-
lene with SÀS and SeÀSe bond cleavage are observed in the
reaction of 2 with Ph S or Ph Se , in which the disulfido com-
2
2
2
2
5
plex [h -1,2,4-(Me C) C H ] U(SPh) (18) and the diselenido
3
3
5
2 2
2
5
complex [h -1,2,4-(Me C) C H ] U(SePh) (19) are formed, re-
3
3
5
2 2
2
spectively (Scheme 9). Figure 10 shows the molecular structure
of 18 and selected bond distances and angles are compiled in
Table 1. The UÀS distances are 2.659(1) Š for S(1) and
Scheme 9. Synthesis of complexes 18–24.
2
.628(1) Š for S(2), and the angle of S(1)-U-S(2) is 100.4(1)8.
Nevertheless, in the presence of suitable substrates, the re-
activity of the uranium metallacyclopropene 2 may also paral-
5
2
lel its thorium analogue [h -1,2,4-(Me C) C H ] Th(h -C Ph ) (Fig-
3
3
5
2 2
2
2
[
6a,11]
ure 3).
For example, insertion of 1 equiv of PhNCS into the
uranium metallacyclopropene moiety of 2 is observed at room
temperature to yield the five-membered heterocyclic complex
5
[
h -1,2,4-(Me C) C H ] U[SC(=NPh)(C Ph )] (20) (Scheme 9). The
3
3
5
2 2
2
2
molecular structure of 20 can be found in Figure 11 and select-
ed bond distances and angles are compiled in Table 1. The UÀ
S
2
distance is 2.649(2) Š, whereas UÀC(37) distance is
.480(10) Š, and the angle of S(1)-U-C(37) is 76.0(2)8.
Moreover, treatment of 2 with 1 equiv of aldehydes RCHO
(
R=p-tolyl, p-ClPh) or ketone (CH ) CO also gives the
2 5
5
five-membered
heterocyclic
compounds
[h -1,2,4-
(
(
Me C) C H ] U[OCR(R’)(C Ph )] (R=H, R’=p-tolyl (21), p-ClPh
3 3 5 2 2 2 2
22); R=R’=(CH ) (23)) (Scheme 9). The molecular structure
2
5
of 23 is shown in Figure 12, whereas the structures of 21 and
2
2 are provided in the Supporting Information. The UÀO dis-
Figure 10. Molecular structure of 18 (thermal ellipsoids drawn at the 35%
probability level).
tances are 2.062(2) Š for 21, 2.069(2) Š for 22 and 2.076(4) Š
for 23, whereas the UÀC distances are 2.581(3) Š for 21 (C37),
2
.577(4) Š for 22 (C43) and 2.572(6) Š for 23 (C35), and the
angles of O-U-C are 67.6(1)8 for 21 (C37), 67.5(1)8 for 22 (C43)
and 67.1(2)8 for 23 (C35). However, when the bulky ketone
quantity of added Ph CO. Product formation may be explained
2
2
by diphenylacetylene substitution to form a uranium h -ketone
[
7]
Ph CO is used as substrate, the diphenylacetylene moiety
intermediate, which immediately reacts with a second mole-
2
5
is replaced to form the uranium pinacolate [h -1,2,4-
cule of Ph CO to furnish 24 (Scheme 9).
2
(
Me C) C H ] U[(OCPh ) ] (24) (Scheme 9), irrespectively of the
3 3 5 2 2 2 2
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(
Me C) C H ] U(II) synthon in the reaction with Ph E (E=S, Se)
3 3 5 2 2 2 2
and unsaturated molecules such as alkynes, imines, ketazine,
bipy, nitriles, organic azides, and azo derivatives, in which the
coordinated diphenylacetylene was readily replaced during the
reaction.
Nevertheless, thorium and uranium metallacyclopropenes
also exhibit similar reactivity patterns, e.g., when exposed to
isothiocyanates, aldehydes and ketones, for which mono inser-
tion of these substrates into the actinide metallacyclopropene
moieties occurs to yield the five-membered heterometallacy-
[
6a,f,g,11]
5
cles.
However, like the thorium metallacyclopropene [h -
2
[6a,11]
1
,2,4-(Me C) C H ] Th(h -C Ph ),
the coordinate PhCCPh in
3
3
5
2 2
2
2
2
is readily displaced, when the sterically encumbered Ph CO is
2
5
Figure 11. Molecular structure of 20 (thermal ellipsoids drawn at the 35%
probability level).
used as substrate, but the metallaoxirane intermediate [h -
2
1,2,4-(Me C) C H ] U(h -Ph CO) is too reactive to be observed
3
3
5
2 2
2
and a second molecule of Ph CO inserts to yield the uranium
2
5
pinacolate [h -1,2,4-(Me C) C H ] U[(OCPh ) ] (24). Further in-
3
3
5
2 2
2 2
vestigations concerning the intrinsic reactivity of actinide met-
allacycles are ongoing and will be reported in due course.
Experimental Section
General procedures
All reactions and product manipulations were carried out under an
atmosphere of dry dinitrogen with rigid exclusion of air and mois-
ture using standard Schlenk or cannula techniques, or in a glove
box. All organic solvents were freshly distilled from sodium benzo-
phenone ketyl immediately prior to use. Diphenylacetylene was
5
purified by sublimation. [h -1,2,4-(Me C) C H ] U=P-2,4,6-tBu C H
(
3
3
5
2 2
3
6
2
[7]
5
[9]
1) and [h -1,2,4-(Me C) C H ] UCl (3) were prepared according
3 3 5 2 2 2
to literature procedures. All other chemicals were purchased from
Aldrich Chemical Co. and Beijing Chemical Co. and used as re-
ceived unless otherwise noted. Infrared spectra were recorded in
Figure 12. Molecular structure of 23 (thermal ellipsoids drawn at the 35%
probability level).
1
KBr pellets on an Avatar 360 Fourier transform spectrometer. H
13
1
and C{ H} NMR spectra were recorded on a Bruker AV 400 spec-
trometer at 400 and 100 MHz, respectively. All chemical shifts are
reported in d units with reference to the residual protons of the
deuterated solvents, which served as internal standards, for proton
and carbon chemical shifts. Melting points were measured on an
X-6 melting point apparatus and were uncorrected. Elemental anal-
yses were performed on a Vario EL elemental analyzer.
Conclusions
The intrinsic reactivity of a stable uranium metallacyclopropene
5
2
complex, h -1,2,4-(Me C) C H ] U(h -C Ph ), was evaluated and
3
3
5
2 2
2
2
compared to that of the other uranium and thorium metallacy-
clopropenes. In analogy to the uranium metallacyclopropene
5
2
Preparation of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2)
3
3
5
2 2
2
2
5
2
[6f]
derivative (h -C Me ) U{h -C (SiMe ) },
density functional
5
5 2
2
3 2
Method A: A toluene (10 mL) solution of PhCꢀCPh (178 mg,
theory (DFT) suggests that the 5f orbitals contribution to the s
5
1
(
.0 mmol) was added to a toluene (10 mL) solution of [h -1,2,4-
2
and p-bonds of the U-(h -C=C) moiety increases substantially
Me C) C H ] U=P-2,4,6-tBu C H (1; 981 mg, 1.0 mmol) with stir-
3 3 5 2 2 3 6 2
compared to the related thorium metallacyclopropene com-
ring at room temperature. After the solution was stirred at 508C
overnight, the solvent was removed. The residue was extracted
with n-hexane (10 mL”3) and filtered. The volume of the filtrate
was reduced to 10 mL, brown crystals of 2 were isolated when this
solution was kept at À208C for two days. Yield: 706 mg (80%).
5
plex, which also renders the bonds between the [h -1,2,4-
2
+
2
2À
(
Me C) C H ] U
and [h -C Ph ]
fragments more covalent
3
3
5
2 2
2
2
than those found in the related thorium metallacyclopropene.
Whereas the coordinated alkyne in the thorium metallacyclo-
1
[6a]
M.p.: 178–1808C (dec.). H NMR (400 MHz, C D ): d=26.59 (s, 4H,
propenes is inert to ligand substitution, it reacts as a nucleo-
phile towards hetero-unsaturated molecules or as a strong
base inducing the inter- or intramolecular CÀH bond activa-
6
6
phenyl), 16.62 (s, 4H, phenyl), 10.79 (d, J=5.6 Hz, 2H, phenyl), 9.30
(
br s, 18H, C(CH ) ), À15.00 (br s, 18H, C(CH ) ), À32.03 (s, 18H,
3
3
3 3
13 1
C(CH ) ) ppm; ring CÀH atoms were not observed. C{ H} NMR
[
6a,b,11]
3 3
tions.
However, in analogy to the uranium metallacyclo-
(
100 MHz, C D ): d=202.7 (UC), 201.8 (phenyl C), 201.0 (phenyl C),
6 6
5
2
[6f,g]
propene (h -C Me ) U{h -C (SiMe ) },
the reactivity patterns
5
5 2
2
3 2
151.4 (phenyl C), 138.4 (phenyl C), 137.9 (C(CH ) ), 137.3 (C(CH ) ),
3 3 3 3
of the uranium complex 2 change considerably, that is, the
uranium complex 2 serves as a synthetically useful [h -1,2,4-
136.7 (C(CH ) ), 85.8 (C(CH ) ), À50.1 (ring C), À51.1 (ring C) ppm;
3
3
3 3
5
one ring C overlapped. IR (KBr): n˜ =2960 (s), 1460 (m), 1384 (m),
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À1
1
1
6
259 (s), 1093 (s), 1020 (s), 800 (s) cm . Anal. Calcd for C H U: C,
PhCꢀCPh were observed by H NMR spectroscopy (100% conver-
sion) after the sample was kept at 408C for one week.
48
68
5.28; H, 7.76. Found: C, 65.35; H, 7.73.
Method B, NMR scale: A C D6 (0.3 mL) solution of PhCꢀCPh
6
(
3.6 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
5
2
Preparation of [h -1,2,4-(Me C) C H ] U(h -CHPhNPh) (6)
3
3
5
2 2
5
charged with [h -1,2,4-(Me C) C H ] U=P-2,4,6-tBu C H (1; 20 mg,
3
3
5
2 2
3
6
2
0
3
3
1
1
.02 mmol) and C D (0.2 mL). Resonances of 2 along with those of
Method A: This compound was prepared as brown microcrystals
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3 3 5 2 2 2 2
0.25 mmol) and PhCH=NPh (46 mg, 0.25 mmol) in toluene (15 mL)
at 1008C and recrystallization from an n-hexane solution by a simi-
6
6
1
5
2
,3-Me -5,7-tBu C H P ( H NMR (400 MHz, C D ): d=7.46 (dd, J=
2
2
8
5
6
6
.8, 1.5 Hz, 2H, phenyl), 4.39 (ddd, J=181.6, 11.9, 7.9 Hz, 1H, PH),
.59 (d, J=3.6 Hz, 1H, CH ), 1.56 (s, 9H, (CH ) C), 1.34 (s, 3H, CH ),
2
3 3
3
.31 (s, 9H, (CH ) C), 1.29 (d, J=3.6 Hz, 1H, CH ), 1.11 (s, 3H,
lar procedure as that in the synthesis of 5. Yield: 177 mg (80%).
3
3
2
[5p]
1
1
CH ) ppm) were observed by H NMR spectroscopy (100% con-
H NMR (400 MHz, C D ): d=129.18 (s, 1H, CHPh), 34.03 (s, 1H,
6 6
3
version) after the sample was kept at 508C overnight.
phenyl), 26.49 (s, 2H, phenyl), 23.78 (s, 1H, phenyl), 13.63 (s, 9H,
C(CH ) ), 13.36 (s, 2H, phenyl), 12.24 (s, 9H, C(CH ) ), 7.42 (s, 1H,
3
3
3 3
phenyl), À0.60 (s, 1H, phenyl), À2.57 (s, 1H, phenyl), À10.04 (s, 9H,
5
2
5
Preparation of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2) and [h -
1
3
3
5
2 2
2
2
C(CH ) ), À17.56 (s, 9H, C(CH ) ), À35.03 (s, 9H, C(CH ) ), À42.50 (s,
3
3
3 3
3 3
,2,4-(Me C) C H ] UCl (4)
3 3 5 2 2
9H, C(CH ) ), À68.53 (s, 1H, phenyl) ppm; ring CÀH atoms were
3
3
not observed. These spectroscopic data agreed with those report-
KC (1.20 g, 8.80 mmol) was added to a toluene (20 mL) solution of
8
[7]
5
ed in the literature.
[
h -1,2,4-(Me C) C H ] UCl (3; 1.94 g, 2.5 mmol) and diphenylacety-
3
3
5
2 2
2
Method B, NMR scale: A C D6 (0.3 mL) solution of PhCH=NPh
lene (0.45 g, 2.5 mmol) with stirring at room temperature. After
this solution was stirred one day at 408C, the solvent was re-
moved. The residue was extracted with n-hexane (20 mL”3) and
filtered. The volume of the filtrate was reduced to 15 mL, green mi-
6
(
3.6 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
0
.02 mmol) and C D (0.2 mL). Resonances of 6 along with those of
6 6
1
PhCꢀCPh were observed by H NMR spectroscopy (100% conver-
crocrystals were isolated when this solution was kept at À208C for
1
sion) after the sample was kept at 1008C for 5 days.
2
days. The H NMR spectrum recorded in C D showed the present
6
6
1
of 2 and 4 ( H NMR (400 MHz, C D ): d=À7.95 (s, 36H, C(CH ) ),
6
6
3 3
À25.40 (s, 18H, C(CH ) ) ppm; protons of the rings were not ob-
5
3
3
Preparation of [h -1,2,4-(Me C) C H ] U(N=CPh ) (7)
3
3
5
2 2
2 2
[9]
served) in a 1:3 ratio. Unfortunately, this mixture could not be
converted to exclusively yield 2 upon prolonged reduction in the
presence of diphenylacetylene with an excess of potassium graph-
Method A: This compound was prepared as brown microcrystals
5
2
from the reaction of [h -1,2,4-(Me
C) C H ] U(h -C Ph ) (2; 221 mg,
3 5 2 2 2 2
3
ite (KC ). Under these conditions, some other yet unidentified spe-
0.25 mmol) and (Ph C=N) (90 mg, 0.25 mmol) in toluene (15 mL)
2
2
8
cies were formed. In addition, on a synthetic scale the mixture of
complex 2 and 4 could not be separated to yield pure materials
because of their similar solubilities. However, a few green crystals
of 4 suitable for X-ray diffraction analysis were selected from those
microcrystals that recrystallized from an n-hexane at À208C, and
the molecular structure of 4 was further verified by X-ray diffrac-
tion analysis (see Supporting Information for details).
at 1008C and recrystallization from a benzene solution by a similar
procedure as that in the synthesis of 5. Yield: 221 mg (83%).
1
H NMR (400 MHz, C
), 12.45 (br s, 18H, C(CH
2H, phenyl), 7.37 (s, 1H, phenyl), 7.04 (s, 2H, phenyl), 2.29 (s, 18H,
C(CH
), 1.45 (s, 9H, phenyl), 1.28 (s, 5H, phenyl), À23.34 (br s,
12H, C(CH
), À75.71 (br s, 2H, ring CH) ppm. These spectroscopic
data were in line with those reported in the literature.
Method B, NMR scale: A C D6 (0.3 mL) solution of (Ph C=N)
D
): d=33.06 (br s, 2H, ring CH), 14.59 (br s,
6
6
6H, C(CH
)
) ), 7.70 (s, 1H, phenyl), 7.41 (s,
3 3
3
3
)
3 3
)
3 3
[7]
5
2
6
2
2
Preparation of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (5)
3
3
5
2 2
4
2
(
7.2 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
Method A: A toluene (10 mL) solution of PhCꢀCCꢀCPh (51 mg,
3
3
5
2 2
2
2
5
0
.02 mmol) and C D (0.2 mL). Resonances of 7 along with those of
6 6
0
(
.25 mmol) was added to a toluene (10 mL) solution of [h -1,2,4-
1
2
PhCꢀCPh were observed by H NMR spectroscopy (100% conver-
Me C) C H ] U(h -C Ph ) (2; 221 mg, 0.25 mmol) with stirring at
3 3 5 2 2 2 2
sion) after the sample was kept at 1008C for 5 days.
room temperature. After the solution was stirred at 408C for one
week, the solvent was removed. The residue was extracted with n-
hexane (10 mL”3) and filtered. The volume of the filtrate was re-
duced to 10 mL, brown crystals of 5 were isolated when this solu-
5
Preparation of [h -1,2,4-(Me C) C H ] U(bipy) (8)
3
3
5
2 2
tion was kept at À208C for two days. Yield: 186 mg (82%). M.p.:
Method A: This compound was prepared as green microcrystals
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3 3 5 2 2 2 2
1
5
2
1
17–1198C (dec.). H NMR (400 MHz, C D ): d=14.35 (s, 4H,
6
6
phenyl), 10.23 (s, 18H, C(CH ) ), 8.70 (s, 4H, phenyl), 8.30 (s, 2H,
0.25 mmol) and bipy (39 mg, 0.25 mmol) in toluene (15 mL) at
1008C and recrystallization from a benzene solution by a similar
procedure as that in the synthesis of 5. Yield: 181 mg (84%).
3
3
phenyl), À1.28 (br s, 18H, C(CH ) ), À15.18 (br s, 18H,
3
3
1
3
1
C(CH ) ) ppm; ring CÀH atoms were not observed. C{ H} NMR
3
3
1
(
100 MHz, C D ): d=294.5 (UCPh), 207.7 (UC), 179.1 (ring C), 175.5
H NMR (400 MHz, C D ): d=1.26 (s, 4H, ring CH), 1.17 (s, 36H,
6
6
6
6
(
(
ring C), 139.2 (phenyl C), 132.7 (phenyl C), 129.2 (phenyl C), 128.3
phenyl C), 49.4 (C(CH ) ), 32.3 (C(CH ) ), 31.9 (C(CH ) ), 29.8
C(CH ) ), À7.47 (d, J=4.9 Hz, 2H, bipy), À9.01 (s, 18H, C(CH ) ),
3
3
3 3
À58.93 (s, 2H, bipy), À99.40 (s, 2H, bipy), À125.80 (s, 2H, bi-
3
3
3 3
3 3
(C(CH ) ) ppm; other carbon atoms overlapped. IR (KBr): n˜ =2958
py) ppm. These spectroscopic data agreed with those reported in
3
3
[7]
(
(
s), 1952 (w, C=C=C=C), 1460 (s), 1361 (s), 1238 (s), 1097 (s), 1070
the literature.
À1
s), 1024 (s), 825 (s) cm . Anal. Calcd for C H U: C, 66.20; H, 7.56.
5
0
68
Method B, NMR scale: A C D (0.3 mL) solution of bipy (3.1 mg,
6
6
Found: C, 66.25; H, 7.53.
0
.02 mmol) was slowly added to a J. Young NMR tube charged
5
2
Method B, NMR scale: A C D (0.3 mL) solution of PhCꢀCCꢀCPh
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3 3 5 2 2 2 2
6
6
(
4.0 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
C D (0.2 mL). Resonances of 8 along with those of PhCꢀCPh were
6
6
5
2
1
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
observed by H NMR spectroscopy (100% conversion) after the
3
3
5
2 2
2
2
0
.02 mmol) and C D (0.2 mL). Resonances of 5 along with those of
sample was kept at 1008C for 3 days.
6
6
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Chemistry—A European Journal
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5
1
Preparation of [h -1,2,4-(Me C) C H ] U[(N=C(C H )) ] (9)
of PhCꢀCPh were observed by H NMR spectroscopy (100% con-
3
3
5
2 2
6
11 2
version) after the sample was kept at room temperature overnight.
Method A: This compound was prepared as brown microcrystals
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
.25 mmol) and C H CN (55 mg, 0.50 mmol) in toluene (15 mL) at
6 11
room temperature and recrystallization from a benzene solution by
5
2
3
3
5
2 2
2
2
5
2
Reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2) with
3
3
5
2 2
2
2
0
Ph CHCN
2
a similar procedure as that in the synthesis of 5. Yield: 188 mg
NMR scale:
A C6D6 (0.3 mL) solution of Ph CHCN (3.9 mg,
2
1
(
(
78%). M.p.: 165–1678C (dec.). H NMR (400 MHz, C D ): d=19.82
br s, 2H, Cy), 18.03 (s, 2H, CH), 15.00 (br s, 2H, Cy), 13.53 (br s, 2H,
6
6
0
.02 mmol) was slowly added to a J. Young NMR tube charged
5
2
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3
3
5
2 2
2
2
Cy), 12.61 (br s, 2H, Cy), 11.47 (s, 18H, C(CH ) ), 9.55 (br s, 2H, Cy),
3
3
C D (0.2 mL). Resonances of 10 along with those of unreacted 2
6
6
8
4
.89 (br s, 2H, Cy), 6.30 (br s, 4H, Cy), 5.32 (d, J=15.2 Hz, 2H, Cy),
.93 (d, J=12.8 Hz, 2H, Cy), À10.01 (s, 36H, C(CH ) ) ppm; protons
1
and PhCꢀCPh were observed by H NMR spectroscopy (50% con-
version based on 2) after the sample was kept at room tempera-
ture overnight.
3
3
1
3
1
of CpH were not observed. C{ H} NMR (100 MHz, C D ): d=216.1
6
6
(
(
N=C), 77.0 (CH), 41.6 (C(CH ) ), 32.5 (C(CH ) ), 31.7 (C(CH ) ), 16.7
3 3 3 3 3 3
CH ), 5.7 (CH ), À18.9 (ring C), À38.8 (ring C) ppm; other carbons
2
2
5
Preparation of [h -1,2,4-(Me C) C H ] U[N=C(Ph)(C Ph )] (11)
3
3
5
2 2
2
2
overlapped. IR (KBr): n˜ =2928 (s), 1450 (s), 1359 (s), 1240 (s), 1180
(
À1
m), 964 (s), 763 (s) cm . Anal. Calcd for C H N U: C, 62.45; H,
4
8
80
2
Method A: This compound was prepared as brown microcrystals
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
8
9
.73; N, 3.03. Found: C, 62.41; H, 8.76; N, 3.02. Brown crystals of
·0.5C H suitable for X-ray structural analysis were grown from an
5
2
3
3
5
2 2
2
2
6
14
0.25 mmol) and PhCN (26 mg, 0.25 mmol) in toluene (15 mL) and
recrystallization from an n-hexane solution by a similar procedure
as in the synthesis of 5. Yield: 212 mg (86%). M.p.: 107–1098C.
n-hexane solution.
Method B, NMR scale: A C D6 (0.3 mL) solution of C H CN
6
6
11
1
(
4.4 mg, 0.04 mmol) was slowly added to a J. Young NMR tube
H NMR (400 MHz, C D ): d=36.09 (s, 2H, ring CH), 18.02 (s, 18H,
6
6
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
C(CH ) ), 17.73 (s, 2H, phenyl), 14.80 (s, 3H, phenyl), 10.61 (s, 2H,
3
3
5
2 2
2
2
3 3
0
.02 mmol) and C D (0.2 mL). Resonances of 9 along with those of
phenyl), 9.98 (s, 1H, phenyl), 3.67 (s, 18H, C(CH ) ), À2.35 (s, 2H,
6
6
3 3
1
PhCꢀCPh were observed by H NMR spectroscopy (100% conver-
phenyl), À3.66 (s, 1H, phenyl), À9.08 (s, 1H, phenyl), À12.03 (s, 1H,
phenyl), À22.14 (s, 2H, phenyl), À22.84 (s, 18H, C(CH ) ), À33.17 (s,
sion) after the sample was kept at room temperature overnight.
3
3
13
1
2
2
H, ring CH) ppm. C{ H} NMR (100 MHz, C D ): d=266.2 (UCPh),
6 6
30.6 (CPh), 181.4 (C=N), 155.4 (phenyl C), 134.2 (phenyl C), 134.0
5
2
Reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2) with
C H CN
3
3
5
2 2
2
2
(phenyl C), 130.4 (phenyl C), 126.9 (phenyl C), 126.3 (phenyl C),
119.7 (phenyl C), 116.0 (phenyl C), 114.8 (phenyl C), 108.3 (phenyl
C), 107.4 (phenyl C), 101.7 (phenyl C), 86.7 (C(CH ) ), 84.9 (C(CH ) ),
6
11
3
3
3 3
NMR scale:
0
A C6D6 (0.3 mL) solution of C H CN (2.2 mg,
6 11
5
2.2 (C(CH ) ), 47.4 (C(CH ) ), 44.1 (C(CH ) ), À1.3 (ring C), À1.8 (ring
3
3
3 3
3 3
.02 mmol) was slowly added to a J. Young NMR tube charged
C), À2.4 (ring C), À4.9 (ring C), À57.2 (ring C) ppm; one C reso-
5
2
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
C D (0.2 mL). Resonances of 9 along with those of unreacted 2
and PhCꢀCPh were observed by H NMR spectroscopy (50% con-
version based on 2) after the sample was kept at room tempera-
ture overnight.
3
3
5
2 2
2
2
nance of Me C-groups overlapped. IR (KBr): n˜ =2958 (s), 1458 (s),
3
6
6
À1
1
361 (s), 1261 (s), 1238 (s), 1095 (s), 1072 (s), 1022 (s), 806 (s) cm .
1
Anal. Calcd for C H NU: C, 66.98; H, 7.46; N, 1.42. Found: C,
55
73
6
7.02; H, 7.43; N, 1.41.
Method B, NMR Scale: A C D (0.3 mL) solution of PhCN (2.1 mg;
6
6
0
.02 mmol) was slowly added to a J. Young NMR tube charged
5
2
5
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
C D (0.2 mL). Resonances of 11 were observed by H NMR spec-
troscopy (100% conversion in 10 min).
Preparation of [h -1,2,4-(Me C) C H ] U[(N=C(CHPh )) ] (10)
3
3
5
2 2
2
2
3
3
5
2 2
2 2
1
6
6
Method A: This compound was prepared as brown crystals from
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
5
2
3
3
5
2 2
2
2
0
.25 mmol) and Ph CHCN (97 mg, 0.50 mmol) in toluene (15 mL) at
5
2
Preparation of [h -1,2,4-(Me C) C H ] U[NHC(=CHPh)(C Ph )]
3
3
5
2 2
2
2
room temperature and recrystallization from an n-hexane solution
by a similar procedure as that in the synthesis of 5. Yield: 218 mg
(12)
1
(
(
80%). M.p.: 104–1068C (dec.). H NMR (400 MHz, C D ): d=39.49
s, 1H, phenyl), 29.51 (s, 1H, phenyl), 23.77 (s, 3H, phenyl), 16.10 (s,
6
6
Method A: This compound was prepared as brown crystals from
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
0.25 mmol) and PhCH CN (30 mg, 0.25 mmol) in toluene (15 mL)
and recrystallization from an n-hexane solution by a similar proce-
dure as in the synthesis of 5. Yield: 205 mg (82%). M.p.: 123–
258C. H NMR (400 MHz, C D ): d=16.49 (s, 18H, C(CH ) ), 14.85
(s, 1H, NH), 8.72 (s, 2H, ring CH), 6.00 (s, 2H, phenyl), 4.51 (t, J=
.5 Hz, 1H, phenyl), 3.90 (t, J=6.8 Hz, 2H, phenyl), 3.62 (s, 1H,
5
2
3
3
5
2 2
2
2
3
1
1
H, phenyl), 13.97 (s, 18H, C(CH ) ), 11.00 (s, 3H, phenyl), 10.45 (s,
3 3
2
H, phenyl), À1.31 (s, 2H, CH), À13.12 (s, 18H, C(CH ) ), À16.00 (s,
3
3
8H, C(CH ) ), À21.16 (s, 7H, phenyl), À62.00 (s, 1H, phenyl) ppm;
3
3
1
3
1
protons of the rings were not observed. C{ H} NMR (100 MHz,
C D ): d=235.1 (C=N), 160.1 (phenyl C), 158.5 (phenyl C), 145.8
1
1
6
6
3 3
6
6
(
phenyl C), 141.0 (phenyl C), 137.8 (phenyl C), 135.7 (phenyl C),
6
1
4
31.5 (phenyl C), 123.7 (phenyl C), 120.6 (phenyl C), 52.9 (C(CH ) ),
3 3
phenyl), 3.09 (d, J=6.2 Hz, 1H, phenyl), 2.24 (d, J=7.2 Hz, 2H,
phenyl), 0.68 (d, J=7.8 Hz, 2H, phenyl), À0.50 (s, 1H, PhCH), À1.68
9.9 (C(CH ) ), 35.1 (C(CH ) ), 17.0 (C(CH ) ), À3.4 (ring C), À42.8
3
3
3 3
3 3
(
ring C), À50.3 (ring C) ppm; other carbons overlapped. IR (KBr):
(
s, 1H, phenyl), À2.08 (s, 18H, C(CH ) ), À6.64 (t, J=6.4 Hz, 1H,
3
3
n˜ =2957 (s), 1595 (s), 1554 (s), 1492 (s), 1452 (s), 1359 (s), 1238 (s),
phenyl), À8.30 (s, 2H, ring CH), À19.26 (s, 18H, C(CH ) ), À38.49 (d,
3
3
À1
9
2
64 (s), 812 (s) cm . Anal. Calcd for C H N U: C, 68.23; H, 7.39; N,
13
1
6
2
80
2
J=4.6 Hz, 2H, phenyl) ppm. C{ H} NMR (100 MHz, C D ): d=322.1
6 6
.57. Found: C, 68.21; H, 7.36; N, 2.60.
(
UCPh), 318.5 (CPh), 302.8 (CNH), 214.5 (phenyl C), 155.8 (phenyl C),
Method B, NMR scale: A C D6 (0.3 mL) solution of Ph CHCN
142.0 (phenyl C), 123.6 (phenyl C), 118.8 (phenyl C), 115.0 (phenyl
C), 107.8 (ring C), 98.6 (ring C), 97.3 (ring C), 97.1 (ring C), 96.9 (ring
C), 78.4 (CHPh), 48.8 (C(CH ) ), 43.2 (C(CH ) ) ppm; other carbons
6
2
(
7.7 mg, 0.04 mmol) was slowly added to a J. Young NMR tube
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
3 3
3 3
0
.02 mmol) and C D (0.2 mL). Resonances of 10 along with those
overlapped. IR (KBr): n˜ =2958 (s), 1591 (m), 1456 (m), 1361 (s), 1240
6
6
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Chemistry—A European Journal
doi.org/10.1002/chem.202100089
À1
1
(
s), 1072 (s), 1028 (s), 808 (s) cm . Anal. Calcd for C H NU: C,
(83%). M.p.: 173–1758C. H NMR (400 MHz, C D ): d=85.85 (s, 2H,
6 6
5
6
75
6
7.24; H, 7.56; N, 1.40. Found: C, 67.26; H, 7.53; N, 1.41.
ring CH), 37.79 (s, 6H, phenyl), 18.84 (s, 18H, C(CH ) ), 12.51 (s, 6H,
3 3
phenyl), 10.19 (s, 3H, phenyl), À18.22 (s, 18H, C(CH ) ), À45.33 (s,
Method B, NMR scale: A C D6 (0.3 mL) solution of PhCH CN
3 3
6
2
13
1
1
8H, C(CH ) ), À47.73 (s, 2H, ring CH) ppm. C{ H} NMR (100 MHz,
(
2.4 mg; 0.02 mmol) was slowly added to a J. Young NMR tube
3 3
5
2
C D ): d=172.6 (phenyl C), 171.9 (phenyl C), 170.8 (phenyl C), 159.5
6 6
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
(
phenyl C), 143.6 (ring C), 141.0 (ring C), 139.5 (ring C), 100.3 (CPh3),
0
.02 mmol) and C D (0.2 mL). Resonances of 12 were observed by
6 6
1
58.2 (C(CH ) ), 57.8 (C(CH ) ), 31.9 (C(CH ) ), 31.8 (C(CH ) ) ppm;
3 3 3 3 3 3 3 3
H NMR spectroscopy (100% conversion in 10 min).
other carbons overlapped. IR (KBr): n˜ =2957 (s), 1485 (m), 1357 (m),
À1
1
236 (m), 1089 (s), 1066 (s), 1030 (s), 806 (s) cm . Anal. Calcd for
5
Preparation of [h -1,2,4-(Me C) C H ] U(=NPh) (13)
3
3
5
2 2
2
C H NU: C, 66.16; H, 7.65; N, 1.46. Found: C, 66.14; H, 7.69; N,
53
73
1
.44. Brown crystals of 16·0.5C H suitable for X-ray structural anal-
6 14
Method A: This compound was prepared as brown crystals from
5
2
ysis were grown from an n-hexane solution.
Method B, NMR scale: A C (0.3 mL) solution of Ph
0.02 mmol) was slowly added to a J. Young NMR tube charged
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3 3 5 2 2 2 2
C
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3
3
5
2 2
2
2
0
.25 mmol) and PhN=NPh (46 mg, 0.25 mmol) in toluene (15 mL)
6
D
6
CN (5.7 mg,
3 3
at 508C and recrystallization from a benzene solution by a similar
procedure as that in the synthesis of 5. Yield: 186 mg (84%).
5
2
1
H NMR (400 MHz, C D ): d=9.48 (t, J=7.5 Hz, 4H, phenyl), 4.99 (s,
6
D
6
(0.2 mL). Resonances of 16 along with those of PhCꢀCPh
6
6
1
4
1
H, ring CH), 3.07 (d, J=6.6 Hz, 4H, phenyl), 1.65 (s, 36H, C(CH ) ),
were observed by H NMR spectroscopy (100% conversion) after
the sample was kept at room temperature overnight.
3
3
.62 (s, 18H, C(CH ) ), 0.17 ppm (t, J=7.2 Hz, 2H, phenyl). These
3
3
[7]
spectroscopic data agreed with those reported in the literature.
Method B, NMR scale: A C D6 (0.3 mL) solution of PhN=NPh
6
5
(
3.6 mg, 0.02 mmol) was slowly added to a J. Young NMR tube
Preparation of [h -1,2,4-(Me
(17)
C)
3
3
C
5
H
2
] U(=NN=CHSiMe
2
)(CN)
3
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
0
.02 mmol) and C D (0.2 mL). Resonances of 13 along with those
6 6
1
Method A: This compound was prepared as orange crystals from
of PhCꢀCPh were observed by H NMR spectroscopy (100% con-
5
2
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3
3
5
2 2
2
2
version) after the sample was kept at 508C for 5 days.
0
.25 mmol) and Me SiCHN (58 mg, 0.50 mmol) in toluene (15 mL)
3 2
at room temperature and recrystallization from an n-hexane solu-
5
Preparation of [h -1,2,4-(Me C) C H ] U[=N(p-tolyl)] (14)
tion by a similar procedure as that in the synthesis of 5. Yield:
3
3
5
2 2
2
1
1
52 mg (72%). M.p.: 149–1518C. H NMR (400 MHz, C D ): d=4.40
6
6
Method A: This compound was prepared as brown crystals from
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
.25 mmol) and bis(p-tolyl)diazene (53 mg, 0.25 mmol) in toluene
15 mL) at 508C and recrystallization from a benzene solution by a
similar procedure as that in the synthesis of 5. Yield: 183 mg
(
s, 18H, C(CH ) ), À1.65 (s, 18H, C(CH ) ), À1.81 (s, 9H, Si(CH ) ),
5
2
3 3
3 3
3 3
3
3
5
2 2
2
2
À3.46 (s, 18H, C(CH ) ) ppm; protons of CpH and CHSi were not
3
3
0
(
13
1
observed. C{ H} NMR (100 MHz, C D ): d=198.2 (CN), 90.1 (CHSi),
6
6
3
8.1 (C(CH ) ), 35.0 (C(CH ) ), 34.9 (C(CH ) ), 33.3 (C(CH ) ), 30.1
3 3 3 3 3 3 3 3
(
C(CH ) ), 29.6 (C(CH ) ), À2.6 (ring C), À3.2 (ring C), À7.0 (ring C),
1
3 3
3 3
(
80%). M.p.: 185–1878C. H NMR (400 MHz, C D ): d=9.34 (d, J=
6 6
.6 Hz, 4H, phenyl), 8.08 (s, 6H, CH ), 5.00 (s, 4H, ring CH), 2.83 (d,
3
29 1
À7.2 (ring C), À8.9 (SiCH ), À10.4 (ring C) ppm. Si{ H} NMR (C D ):
3
6
6
7
d=À1.1 ppm. IR (KBr): n˜ =2957 (s), 2069 (s), 1944 (w, CN), 1599
J=4.8 Hz, 4H, phenyl), 1.67 (s, 36H, C(CH ) ), 1.63 (s, 18H,
3
3
(
(
m), 1564 (s), 1492 (m), 1458 (m), 1357 (s), 1242 (s), 1166 (m), 839
1
3
1
C(CH ) ) ppm. C{ H} NMR (100 MHz, C D ): d=187.2 (phenyl C),
3
3
6
6
À1
s) cm . Anal. Calcd for C H N SiU: C, 55.43; H, 8.11; N, 4.97.
39
68
3
1
1
66.7 (phenyl C), 142.8 (phenyl C), 140.3 (phenyl C), 118.8 (ring C),
05.9 (ring C), 104.6 (ring C), 38.1 (C(CH ) ), 37.9 (C(CH ) ), 35.8
C(CH ) ), 31.5 (C(CH ) ), 23.6 (CH ) ppm. IR (KBr): n˜ =2958 (s), 1460
s), 1361 (s), 1240 (s), 1099 (s), 821 (s) cm . Anal. Calcd for
C H N U: C, 63.00; H, 7.93; N, 3.06. Found: C, 63.04; H, 7.93; N,
Found: C, 55.44; H, 8.09; N, 5.00.
Method B, NMR scale: A C D6 (0.3 mL) solution of Me SiCHN
2
3
3
3 3
(
(
6
3
3
3
3 3
3
À1
(4.6 mg, 0.04 mmol) was slowly added to a J. Young NMR tube
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
48
72
2
0
.02 mmol) and C D (0.2 mL). Resonances of 17 along with those
6 6
3
.04.
1
of PhCꢀCPh and (Me SiNH) ( H NMR (400 MHz, C D ): d=2.43 (s,
3
2
6
6
Method B, NMR scale: A C D6 (0.3 mL) solution of bis(p-tolyl)di-
azene (4.2 mg, 0.02 mmol) was slowly added to a J. Young NMR
tube charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
.02 mmol) and C D (0.2 mL). Resonances of 14 along with those
6 6
6
1
2
H, NH), 0.28 (s, 18H, Si(CH ) ) ppm) were observed by H NMR
3 3
spectroscopy (100% conversion) after the sample was kept at
room temperature overnight.
5
2
3
3
5
2 2
2
2
0
1
of PhCꢀCPh were observed by H NMR spectroscopy (100% con-
version) after the sample was kept at 508C for 5 days.
5
Preparation of [h -1,2,4-(Me C) C H ] U(SPh) (18)
3
3
5
2 2
2
Method C, NMR scale: A C D6 (0.3 mL) solution of p-tolylN3
6
(
5.3 mg, 0.04 mmol) was slowly added to a J. Young NMR tube
Method A: This compound was prepared as brown crystals from
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3 3 5 2 2 2 2
5
2
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
0
.02 mmol) and C D (0.2 mL). Resonances of 14 along with those
0.25 mmol) and Ph2S2 (55 mg, 0.25 mmol) in toluene (15 mL) at
508C and recrystallization from an n-hexane solution by a similar
6
6
1
of PhCꢀCPh were observed by H NMR spectroscopy (100% con-
version) after the sample was kept at room temperature overnight.
procedure as that in the synthesis of 5. Yield: 201 mg (87%). M.p.:
1
1
68–1708C (dec.). H NMR (400 MHz, C D ): d=6.08 (s, 36H,
6
6
5
C(CH
3
)
3
), À0.28 (d, J=5.8 Hz, 2H, phenyl), À0.35 (s, 4H, phenyl),
Preparation of [h -1,2,4-(Me C) C H ] U=NCPh (16)
3
3
5
2 2
3
À9.47 (s, 18H, C(CH ) ), À24.22 (s, 4H, phenyl) ppm; ring CÀH
3
3
13
1
Method A: This compound was prepared as brown microcrystals
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
atoms were not observed. C{ H} NMR (100 MHz, C D ): d=165.4
6 6
5
2
(ring C), 164.6 (ring C), 163.7 (ring C), 133.4 (phenyl C), 133.2
3
3
5
2 2
2
2
0
.25 mmol) and Ph CN (72 mg, 0.25 mmol) in toluene (15 mL) at
(phenyl C), 103.0 (phenyl C), 102.8 (phenyl C), 67.4 (C(CH ) ), 46.0
3
3
3 3
room temperature and recrystallization from a benzene solution by
(C(CH ) ), 39.2 (C(CH ) ) ppm; other carbons overlapped. IR (KBr):
3
3
3 3
a similar procedure as that in the synthesis of 5. Yield: 209 mg
n˜ =2958 (s), 1577 (s), 1473 (s), 1361 (s), 1238 (s), 1080 (s), 1024 (s),
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À1
5
8
5
31 (s) cm . Anal. Calcd for C H S U: C, 59.85; H, 7.42. Found: C,
Preparation of [h -1,2,4-(Me C) C H ] U[OCH(p-tolyl)-
3 3 5 2 2
4
6
68
2
9.82; H, 7.43.
(
C Ph )]·0.5C H (21·0.5C H )
2 2 6 6 6 6
Method B, NMR scale: A C D (0.3 mL) solution of Ph S (4.4 mg,
6
6
2 2
Method A: This compound was prepared as orange crystals from
0
.02 mmol) was slowly added to a J. Young NMR tube charged
5
2
5
2
the reaction of [h -1,2,4-(Me
C) C H ] U(h -C Ph ) (2; 221 mg,
3 3 5 2 2 2 2
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3
3
5
2 2
2
2
0
.25 mmol) and p-tolylCHO (30 mg, 0.25 mmol) in toluene (15 mL)
C6D6 (0.2 mL). Resonances of 18 along with those of PhCꢀCPh
1
at room temperature and recrystallization from a benzene solution
were observed by H NMR spectroscopy (100% conversion) after
by a similar procedure as in the synthesis of 5. Yield: 219 mg
the sample was kept at 508C overnight.
1
(
84%). M.p.: 139–1418C. H NMR (400 MHz, C D ): d=126.96 (s, 1H,
6
6
ring CH), 77.14 (s, 1H, ring CH), 41.94 (s, 2H, phenyl), 19.77 (s, 2H,
phenyl), 17.39 (br s, 20H, phenyl, OCH and C(CH ) ), 15.38 (s, 2H,
3
3
5
phenyl), 9.44 (s, 1H, phenyl), 9.32 (s, 2H, phenyl), 9.11 (s, 3H, CH3),
Preparation of [h -1,2,4-(Me C) C H ] U(SePh) (19)
3
3
5
2 2
2
7
.15 (s, 3H, C H ), À4.06 (s, 9H, C(CH ) ), À4.51 (s, 2H, phenyl),
6
6
3 3
Method A: This compound was prepared as brown microcrystals
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
À5.80 (s, 2H, phenyl), À11.94 (s, 9H, C(CH
3
)
3
), À17.51 (s, 9H,
), À31.77 (s, 1H, ring CH), À58.53
): d=247.6
5
2
C(CH
)
), À19.11 (s, 9H, C(CH
)
3
3
3
5
2 2
2
2
3
3
3
1
13
0
5
.25 mmol) and Ph Se (78 mg, 0.25 mmol) in toluene (15 mL) at
ppm (s, 1H, ring CH). C{ H} NMR (100 MHz, C
6
D
6
2
2
08C and recrystallization from an n-hexane solution by a similar
(UCPh), 171.1 (CPh), 154.5 (phenyl C), 149.5 (phenyl C), 134.5
(phenyl C), 128.5 (C ), 123.3 (ring C), 119.1 (ring C), 112.4 (ring C),
100.1 (ring C), 66.0 (CHO), 45.6 (C(CH ), 29.1 (C(CH ), 27.1
(C(CH ), 16.6 (CH ) ppm; other carbons overlapped. IR (KBr): n˜ =
procedure as that in the synthesis of 4. Yield: 193 mg (82%). M.p.:
H
6 6
1
1
34–1368C (dec.). H NMR (400 MHz, C D ): d=5.76 (br s, 36H,
3
)
3
)
3 3
6
6
C(CH ) ), 0.99 (s, 2H, phenyl), À8.42 (s, 18H, C(CH ) ), À20.14 (s, 4H,
)
3
3
3
3
3
3 3
phenyl), À21.06 (s, 4H, phenyl), À22.64 (s, 4H, ring CH) ppm.
2958 (s), 1384 (m), 1359 (s), 1240 (s), 1060 (s), 1003 (s), 821
13
1
À1
C{ H} NMR (100 MHz, C D ): d=174.1 (ring C), 173.4 (ring C), 172.6
(s) cm . Anal. Calcd for C59
H79OU: C, 67.99; H, 7.64. Found: C,
6
6
(
(
ring C), 134.0 (phenyl C), 129.2 (phenyl C), 118.6 (phenyl C), 103.9
phenyl C), 69.1 (C(CH ) ), 48.4 (C(CH ) ), 32.6 (C(CH ) ), 31.5
67.97; H, 7.62.
3
3
3 3
3 3
Method B, NMR scale: A C D6 (0.3 mL) solution of p-tolylCHO
6
(
1
C(CH ) ) ppm. IR (KBr): n˜ =2958 (s), 1575 (s), 1471 (s), 1361 (s),
(2.4 mg; 0.02 mmol) was slowly added to a J. Young NMR tube
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3 3 5 2 2 2 2
3
3
À1
5
2
238 (s), 1020 (s), 831 (m), 732 (s) cm . Anal. Calcd for C H Se U:
40
63
2
C, 51.12; H, 6.76. Found: C, 51.14; H, 6.73.
0.02 mmol) and C D (0.2 mL). Resonances of 21 were observed by
6 6
H NMR spectroscopy (100% conversion) after the sample was kept
1
Method B. NMR scale: A C D (0.3 mL) solution of Ph Se (6.2 mg,
6
6
2
2
0
.02 mmol) was slowly added to a J. Young NMR tube charged
at room temperature overnight.
5
2
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3
3
5
2 2
2
2
C6D6 (0.2 mL). Resonances of 19 along with those of PhCꢀCPh
1
were observed by H NMR spectroscopy (100% conversion) after
5
Preparation of [h -1,2,4-(Me C) C H ] U[OCH(p-ClPh)-
(
3
3
5
2 2
the sample was kept at 508C overnight.
C Ph )]·1.5C H (22·1.5C H )
2 2 6 6 6 6
Method A: This compound was prepared as orange crystals from
5
2
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3
3
5
2 2
2
2
5
Preparation of [h -1,2,4-(Me C) C H ] U[SC(=NPh)(C Ph )]
3
3
5
2 2
2
2
0
.25 mmol) and p-ClPhCHO (35 mg, 0.25 mmol) in toluene (15 mL)
(20)
at room temperature and recrystallization from a benzene solution
by a similar procedure as in the synthesis of 5. Yield: 245 mg
Method A: This compound was prepared as brown crystals from
1
5
2
(86%). M.p.: 143–1458C. H NMR (400 MHz, C
6
D ): d=122.11 (s, 1H,
6
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3
3
5
2 2
2
2
ring CH), 74.37 (s, 1H, ring CH), 40.61 (s, 2H, phenyl), 19.46 (s, 2H,
phenyl), 15.39 (br s, 20H, phenyl, OCH and C(CH ) ), 14.95 (s, 2H,
0
.25 mmol) and PhNCS (34 mg, 0.25 mmol) in toluene (15 mL) at
3
3
room temperature and recrystallization from a benzene solution by
phenyl), 9.36 (s, 1H, phenyl), 9.19 (s, 2H, phenyl), 7.15 (s, 9H, C H ),
6
6
a similar procedure as in the synthesis of 5. Yield: 209 mg (82%).
1
À3.62 (s, 9H, C(CH
3
)
3
), À4.31 (s, 2H, phenyl), À5.50 (s, 2H, phenyl),
M.p.: 155–1578C. H NMR (400 MHz, C D ): d=53.36 (s, 2H, ring
6
6
À11.38 (s, 9H, C(CH ) ), À16.82 (s, 9H, C(CH ) ), À18.65 (s, 9H,
3
3
3 3
CH), 21.16 (s, 18H, C(CH ) ), 4.29 (s, 1H, phenyl), 4.04 (s, 2H,
3
3
C(CH ) ), À30.75 (s, 1H, ring CH), À53.49 (s, 1H, ring CH) ppm.
3
3
phenyl), 3.52 (s, 2H, phenyl), 3.03 (d, J=5.8 Hz, 2H, phenyl), 2.52 (s,
H, phenyl), 1.88 (d, J=3.6 Hz, 2H, phenyl), 1.22 (s, 1H, phenyl),
À5.65 (s, 2H, phenyl), À7.25 (s, 18H, C(CH ) ), À7.87 (s, 2H,
13
1
C{ H} NMR (100 MHz, C D ): d=245.5 (UCPh), 171.1 (CPh), 150.6
6
6
1
(
1
phenyl C), 149.6 (phenyl C), 148.7 (phenyl C), 147.8 (phenyl C),
34.5 (phenyl C), 129.3 (phenyl C), 128.5 (C H ), 125.6 (phenyl C),
3
3
6
6
phenyl), À18.18 (s, 18H, C(CH ) ), À33.80 (s, 2H, ring CH) ppm.
3
3
13
1
123.3 (ring C), 119.4 (ring C), 112.2 (ring C), 112.0 (ring C), 100.6
C{ H} NMR (100 MHz, C D ): d=204.7 (UCPh), 143.6 (phenyl C),
6
6
(
ring C), 65.1 (CHO), 46.2 (C(CH ) ), 25.5 (C(CH ) ), 17.8 (C(CH ) ), 7.9
3 3 3 3 3 3
1
25.1 (phenyl C), 123.4 (phenyl C), 122.4 (phenyl C), 120.2 (phenyl
(
1
C(CH ) ) ppm. IR (KBr): n˜ =2958 (s), 1487 (s), 1361 (s), 1240 (s),
087 (s), 1070 (s), 1004 (s), 821 (s) cm . Anal. Calcd for C H ClOU:
64 82
3 3
C), 118.9 (phenyl C), 110.5 (ring C), 110.3 (ring C), 103.7 (ring C),
À1
9
4
7.9 (ring C), 97.1 (ring C), 96.3 (CPh), 92.2 (C=N), 60.3 (C(CH ) ),
3 3
C, 67.38; H, 7.24. Found: C, 67.36; H, 7.22.
1.7 (C(CH ) ), 41.6 (C(CH ) ) ppm; other carbons overlapped. IR
3
3
3 3
Method B, NMR scale: A C D6 (0.3 mL) solution of p-ClPhCHO
(
1
KBr): n˜ =2957 (s), 1593 (m), 1491 (s), 1384 (s), 1361 (s), 1217 (s),
6
À1
(
2.8 mg; 0.02 mmol) was slowly added to a J. Young NMR tube
112 (s), 823 (s) cm . Anal. Calcd for C H NSU: C, 64.87; H, 7.23,
5
5
73
5
2
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
N, 1.38. Found: C, 64.85; H, 7.24, N, 1.35.
3
3
5
2 2
2
2
0
.02 mmol) and C D (0.2 mL). Resonances of 22 were observed by
6 6
Method B, NMR scale: A C D (0.3 mL) solution of PhNCS (2.7 mg;
6
6
1
H NMR spectroscopy (100% conversion) after the sample was kept
at room temperature overnight.
0
.02 mmol) was slowly added to a J. Young NMR tube charged
5
2
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3
3
5
2 2
2
2
1
C D (0.2 mL). Resonances of 20 were observed by H NMR spec-
6
6
troscopy (100% conversion) after the sample was kept at room
temperature overnight.
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Full Paper
Chemistry—A European Journal
doi.org/10.1002/chem.202100089
5
[19]
Preparation of [h -1,2,4-(Me C) C H ] U{OC[(CH ) ](C Ph )}
correction was applied using the SADABS program. All structures
3
3
5
2 2
2 5
2
2
were solved by direct methods and refined by full-matrix least
(23)
2
[20]
squares on F using the SHELXL program package. All the hydro-
gen atoms were geometrically fixed using the riding model. The
crystal data and experimental data for 2, 5, 9, 10, 12, 14, 16–18
and 20–23 are summarized in the Supporting Information. Select-
ed bond lengths and angles are listed in Table 1. It is of note that
the structural data of 2 were relatively poor due to crystal twin-
Method A: This compound was prepared as orange microcrystals
5
2
from the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3
3
5
2 2
2
2
0
.25 mmol) and (CH ) CO (25 mg, 0.25 mmol) in toluene (15 mL) at
2 5
room temperature and recrystallization from a benzene solution by
a similar procedure as in the synthesis of 5. Yield: 195 mg (76%).
1
M.p.: 161–1638C. H NMR (400 MHz, C D ): d=55.40 (s, 2H, ring
À3
6
6
ning, which led to a large positive residual density (9.77 eA )
CH), 28.55 (br s, 4H, phenyl), 22.65 (s, 2H, phenyl), 19.72 (s, 4H,
phenyl), 12.95 (s, 1H, Cy), 10.86 (s, 4H, Cy), 9.88 (s, 2H, Cy), À5.09
close to the uranium atom (0.99 Š) and also to low bond precision
within the CÀC distances (0.02776 Š). These B level alerts in the
checkCIF could not be removed on refinement.
(
s, 3H, Cy), À6.57 (s, 9H, C(CH ) ), À15.85 (br s, 45H, C(CH ) ),
3
3
3 3
13 1
À32.54 (s, 2H, ring CH) ppm. C{ H} NMR (100 MHz, C D ): d=
6
6
Deposition numbers 2054372 (2), 2054384 (5), 2054379 (9),
1
1
70.1 (CPh), 134.0 (phenyl C), 132.3 (phenyl C), 129.4 (phenyl C),
27.9 (phenyl C), 122.4 (ring C), 120.2 (ring C), 117.9 (ring C), 99.0
2
(
2
054374 (10), 2054373 (12), 2054376 (14), 2054375 (16), 2054377
17), 2054382 (18), 2054378 (20), 2054381 (21), 2054383 (22), and
054380 (23) contain the supplementary crystallographic data for
(
(
ring C), 61.3 (CO), 47.0 (C(CH ) ), 44.1 (C(CH ) ), 35.7 (CH ), 30.5
3 3 3 3 2
CH ), 29.7 (CH ) ppm; other carbons were not observed. IR (KBr):
2
2
this paper. These data are provided free of charge by the joint
Cambridge Crystallographic Data Centre and Fachinformationszen-
trum Karlsruhe Access Structures service.
À1
n˜ =2960 (s), 1384 (s), 1259 (s), 1089 (s), 1022 (s), 798 (s) cm . Anal.
Calcd for C H OU: C, 66.10; H, 8.01. Found: C, 66.08; H, 8.02.
5
4
78
Brown crystals of 23·0.5C H14 suitable for X-ray structural analysis
6
were grown from an n-hexane solution.
Computational methods
Method B, NMR scale: A C D6 (0.3 mL) solution of (CH ) CO
6
2 5
(
2.0 mg; 0.02 mmol) was slowly added to a J. Young NMR tube
All calculations were carried out with the Gaussian 09 program
(G09), employing the B3PW91 functional, plus a polarizable con-
5
2
[21]
charged with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg,
3
3
5
2 2
2
2
0
.02 mmol) and C D (0.2 mL). Resonances of 23 were observed by
tinuum model (PCM) (denoted as B3PW91-PCM), with standard 6-
31G(d) basis set for C and H and a quasi-relativistic 5f-in-valence
effective-core potential (ECP60MWB) treatment with 60 electrons in
the core region for U and the corresponding optimized segmented
((14s13p10d8f6g)/[10s9p5d4f3g]) basis set for the valence shells of
6
6
1
H NMR spectroscopy (100% conversion) after the sample was kept
at room temperature overnight.
5
Preparation of [h -1,2,4-(Me C) C H ] U[(OCPh ) ] (24)
3
3
5
2 2
2 2
[22]
U, to fully optimize the geometries of the complexes.
Method A: This compound was prepared as orange crystals from
5
2
the reaction of [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 221 mg,
3
3
5
2 2
2
2
0
6
.25 mmol) and Ph CO (91 mg, 0.50 mmol) in toluene (15 mL) at Acknowledgements
2
08C and recrystallization from a benzene solution by a similar
procedure as that in the synthesis of 5. Yield: 224 mg (84%).
This work was supported by the National Natural Science
Foundation of China (Grant No. 21871029, 21573021,
1
H NMR (400 MHz, C D ): d=61.95 (s, 2H, ring CH), 27.41 (s, 1H,
6
6
phenyl), 23.01 (s, 1H, phenyl), 16.08 (s, 1H, phenyl), 13.84 (s, 18H,
2
1672024), and the Deutsche Forschungsgemeinschaft (DFG)
C(CH ) ), 13.42 (s, 1H, phenyl), 9.72 (s, 2H, phenyl), 8.43 (s, 2H,
3
3
through the Heisenberg program (WA 2513/6). Open access
funding enabled and organized by Projekt DEAL.
phenyl), 7.66 (s, 4H, phenyl), 7.01 (s, 5H, phenyl), 4.61 (s, 1H,
phenyl), 2.90 (s, 1H, phenyl), À1.30 (s, 1H, phenyl), À5.29 (s, 18H,
C(CH ) ), À23.24 (s, 2H, ring CH), À43.97 (s, 18H, C(CH ) ) ppm.
3
3
3 3
These spectroscopic data agreed with those reported in the litera-
[7]
Conflict of interest
ture.
Method B, NMR scale: A C D (0.3 mL) solution of Ph CO (7.3 mg,
6
6
2
The authors declare no conflict of interest.
0
.04 mmol) was slowly added to a J. Young NMR tube charged
5
2
with [h -1,2,4-(Me C) C H ] U(h -C Ph ) (2; 18 mg, 0.02 mmol) and
3
3
5
2 2
2
2
C6D (0.2 mL). Resonances of 24 along with those of PhCꢀCPh
6
Keywords: actinides
complexes · reactivity · uranium
·
bonding
·
metallacyclopropene
1
were observed by H NMR spectroscopy (100% conversion) after
the sample was kept at 608C for 5 days.
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Manuscript received: January 9, 2021
Accepted manuscript online: February 9, 2021
Version of record online: March 16, 2021
Chem. Eur. J. 2021, 27, 6767 – 6782
www.chemeurj.org
6782 ꢀ 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH