A R T I C L E S
Roger et al.
δ 7.56 (s, 2H, m-H), 3.43 (s, 1H, SH), 1.61 (s, 18H, o-tBu), 1.30 (s,
9H, p-tBu). Anal. Calcd for C18H30S: C, 77.63; H, 10.86; S, 11.51.
Found: 77.67; H, 10.85; S, 11.42.
benzene-d6, 23 °C) δ 7.68 (s, 6H, m-H), 1.59 (s, 54H, o-tBu), 1.48 (s,
27H, p-tBu). Anal. Calcd for C54H87S3La: C, 66.77; H, 9.03; S, 9.90.
Found: 66.52; H, 8.84; S, 9.75. Recrystallization from toluene at -25
°C yielded colorless crystals of 6 suitable for X-ray diffraction analysis.
Synthesis of Ce(SMes*)3 (7). A flask was charged with Ce-
[N(SiMe3)2]3 (78.3 mg, 0.126 mmol) and HSMes* (105.1 mg, 0.377
mmol), and cyclohexane (10 mL) was condensed in it. After stirring
for 24 h at 20 °C, the yellow solution was filtered and evaporated to
Reaction of U(NEt2)4 and 3 mol equiv of HSMes*. Crystals of
U(SMes*)3(NEt2)(py)‚0.5py (1‚0.5py). An NMR tube was charged with
U(NEt2)4 (5.0 mg, 0.010 mmol) and HSMes* (8.0 mg, 0.030 mmol) in
1
THF-d8 (0.4 mL). After 2 h at 20 °C, the H NMR spectrum showed
1
the quantitative formation of U(SMes*)3(NEt2)(THF). H NMR (200
1
dryness, giving a yellow powder of 7 (120 mg, 98%). H NMR (200
MHz, THF-d8, 23 °C) δ 137.95 (br s, w1/2 ) 100 Hz, 4H, CH2), 55.33
(s, 6H, Me), 1.02 (s, 6H, m-H), 0.70 (s, 27H, p-tBu), -17.46 (s, 54H,
o-tBu). The orange solution was evaporated to dryness, and recrystal-
lization of the residue from pyridine at -25 °C gave orange crystals
of 1‚0.5py suitable for X-ray diffraction analysis.
Synthesis of U(SMes*)[N(SiMe3)2]3 (2). A flask was charged with
U[N(SiMe3)SiMe2CH2][N(SiMe3)2]2 (71.8 mg, 0.10 mmol) and HSMes*
(27.8 mg, 0.10 mmol), and toluene (15 mL) was condensed in it. After
stirring for 3 h at 20 °C, the orange solution was filtered and evaporated
to dryness, giving an orange powder of 2 (95 mg, 95%). 1H NMR (200
MHz, benzene-d6, 23 °C) δ 4.39 (s, 2H, m-H), 0.61 (s, 18H, o-tBu),
-0.01 (s, 9H, p-tBu), -5.27 (s, 54H, Me). Anal. Calcd for C36H83N3-
SSi6U: C, 43.38; H, 8.39; N, 4.22; S, 3.22. Found: 43.32; H, 8.26; N,
4.11; S, 3.39. Orange crystals of 2 suitable for X-ray diffraction analysis
were deposited from a toluene solution.
MHz, benzene-d6, 23 °C) δ 9.71 (s, 6H, m-H), 3.15 (s, 27H, p-tBu),
-6.92 (s, 54H, o-tBu). Anal. Calcd for C54H87S3Ce: C, 66.69; H, 9.02;
S, 9.89. Found: 66.41; H, 8.85; S, 9.65. Recrystallization from toluene
at -25 °C yielded yellow crystals of 7 suitable for X-ray diffraction
analysis.
Synthesis of Pr(SMes*)3 (8). Pr[N(SiMe3)2]3 was prepared by
treating Pr(SO3CF3)3 (787 mg, 1.34 mmol) with NaN(SiMe3)2 (738 mg,
4.02 mmol) in a mixture of THF (40 mL) and toluene (20 mL). The
reaction mixture was stirred at 85 °C for 24 h. After evaporation to
dryness, sublimation of the yellow powder (90 °C, 10-3 mbar) afforded
a green powder of Pr[N(SiMe3)2]3 (85 mg, 10%). 1H NMR (200 MHz,
benzene-d6) δ -8.67 (s, Me). A flask was charged with Pr[N(SiMe3)2]3
(40.3 mg, 0.065 mmol) and HSMes* (54.5 mg, 0.195 mmol), and
toluene (15 mL) was condensed in it. After stirring for 20 h at 20 °C,
the pale-green solution was filtered and evaporated to dryness, giving
a pale-green powder of 8 (41.6 mg, 66%). 1H NMR (200 MHz, benzene-
d6, 23 °C) δ 13.38 (s, 6H, m-H), 6.11 (s, 27H, p-tBu), -20.10 (s, 54H,
o-tBu). Anal. Calcd for C54H87S3Pr: C, 66.63; H, 9.01; S, 9.88.
Found: 66.34; H, 8.87; S, 9.68. Recrystallization from toluene at -25
°C yielded colorless crystals of 8 suitable for X-ray diffraction analysis.
Synthesis of Nd(SMes*)3 (9). A flask was charged with Nd-
[N(SiMe3)2]3 (76.9 mg, 0.123 mmol) and HSMes* (102.9 mg, 0.369
mmol), and cyclohexane (10 mL) was condensed in it. After stirring
for 3 h at 20 °C, the green solution was filtered and evaporated to
Reaction of U[N(SiMe3)SiMe2CH2][N(SiMe3)2]2 and 3 mol equiv
of HSMes*. An NMR tube was charged with U[N(SiMe3)SiMe2CH2]-
[N(SiMe3)2]2 (7.0 mg, 0.010 mmol) and HSMes* (8.0 mg, 0.030 mmol)
in toluene-d8 (0.4 mL). After 2 h at 110 °C, the spectrum of the red
solution showed the quantitative formation of U(SMes*)3[N(SiMe3)2].
1H NMR (200 MHz, toluene-d8, 23 °C) δ 4.58 (s, 6H, m-H), 0.85 (s,
54H, o-tBu), -0.47 (s, 27H, p-tBu), -7.66 (s, 18H, Me).
Synthesis of U(SMes*)(BH4)3 (3). A flask was charged with
U(BH4)4 (47.0 mg, 0.16 mmol) and KSMes* (50.0 mg, 0.16 mmol),
and toluene (15 mL) was condensed in it. After stirring for 1 h at 20
°C, the red solution was filtered and evaporated to dryness, giving a
1
dryness, giving a green powder of 9 (115 mg, 96%). H NMR (200
MHz, benzene-d6, 23 °C) δ 12.46 (s, 6H, m-H), 5.15 (s, 27H, p-tBu),
-12.60 (s, 54H, o-tBu). Anal. Calcd for C54H87S3Nd: C, 66.40; H,
8.98; S, 9.85. Found: 66.13; H, 8.91; S, 9.73. Recrystallization from
toluene at -25 °C yielded green crystals of 9 suitable for X-ray
diffraction analysis.
1
red oil of 3 (72 mg, 81%). H NMR (200 MHz, toluene-d8, 23 °C) δ
105 (br s, w1/2 ) 700 Hz, 4H, BH4), -5.77 (s, 9H, p-tBu), -10.43 (s,
18H, o-tBu), -22.25 (s, 2H, m-H). Anal. Calcd for C18H41B3SU: C,
38.60; H, 7.38; S, 5.73. Found: 38.86; H, 7.42; S, 5.60.
Synthesis of U(SMes*)4 (4). A flask was charged with U(BH4)4
(24.0 mg, 0.081 mmol) and KSMes* (108 mg, 0.341 mmol), and toluene
(10 mL) was condensed in it. After stirring for 2 h at 20 °C, the black
solution was filtered and evaporated to dryness, giving a black powder
of 4 (70 mg, 64%). 1H NMR (200 MHz, toluene-d8, 23 °C) δ 3.51 (s,
8H, m-H), -0.47 (s, 72H, o-tBu), -1.57 (s, 36H, p-tBu). Coalescence
of the signals corresponding to the o-tBu groups and aromatic H was
observed at -70 °C, but the slow-limit spectrum could not be obtained.
Anal. Calcd for C72H116S4U: C, 64.15; H, 8.67; S, 9.52. Found: 64.02;
H, 8.64; S, 9.33. Recrystallization from benzene yielded black crystals
of 4‚3C6H6 suitable for X-ray diffraction analysis.
Crystallographic Data Collection and Structure Determination.
The data were collected on a Nonius Kappa-CCD area detector
diffractometer34 using graphite-monochromated Mo KR radiation (λ
) 0.71073 Å). The crystals were introduced in glass capillaries with a
protective “Paratone-N” oil (Hampton Research) coating. The unit cell
parameters were determined from 10 frames, and they were then refined
on all data. The data (æ and ω scans with 2° steps) were processed
with HKL2000.35 The structures were solved by Patterson map
interpretation with SHELXS-97 and subsequent Fourier-difference
synthesis and refined by full-matrix least-squares on F2 with SHELXL-
97.36 Absorption effects were corrected empirically with the DELABS
program in PLATON.37
Two compounds, 6 and 7, present an abrupt phase transition with a
critical temperature of about 148(2) and 130(2) K, respectively. In both
cases, the structure of the high-temperature phase is isomorphous to
those of compounds 5, 8, and 9. The structure of 6 at 100 K has also
been determined and is given as Supporting Information, but that of 7
could not be solved, possibly due to microscopic twinning. Due to low
crystal quality, the structure of 7 at 135 K could not be refined
satisfyingly, and all attempts to grow better crystals failed. This is why
this structure has not been used for fine geometric comparisons with
the other complexes, whereas the structure of 6 at 150 K has been
Synthesis of U(SMes*)3 (5). A flask was charged with U[N-
(SiMe3)2]3 (104.3 mg, 0.145 mmol) and HSMes* (95.2 mg, 0.342
mmol), and cyclohexane (5 mL) was condensed in it. After stirring for
2 h at 20 °C, the black solution was filtered and evaporated to dryness,
giving a black powder of 5 (120 mg, 77%). 1H NMR (200 MHz,
benzene-d6, 23 °C) δ 12.95 (s, 6H, m-H), 5.66 (s, 27H, p-tBu), -13.27
1
(s, 54H, o-tBu). H NMR (200 MHz, toluene-d8, -70 °C) δ 18.56 (s,
6H, m-H), 9.37 (s, 27H, p-tBu), -24.79 (s, 54H, o-tBu). Anal. Calcd
for C54H87S3U: C, 60.59; H, 8.19; S, 8.99. Found: 60.31; H, 8.07; S,
8.79. Recrystallization from toluene at -25 °C yielded black crystals
of 5 suitable for X-ray diffraction analysis.
Synthesis of La(SMes*)3 (6). A flask was charged with La-
[N(SiMe3)2]3 (30.4 mg, 0.049 mmol) and HSMes* (40.9 mg, 0.147
mmol), and toluene (15 mL) was condensed in it. After stirring for 2
h at 20 °C, the colorless solution was filtered and evaporated to dryness,
giving a white powder of 6 (45.7 mg, 96%). 1H NMR (200 MHz,
(34) Kappa-CCD Software; Nonius BV: Delft, The Netherlands, 1998.
(35) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.
(36) Sheldrick, G. M. SHELXS-97 and SHELXL-97; University of Go¨ttingen:
Go¨ttingen, Germany, 1997.
(37) Spek, A. L. PLATON; University of Utrecht: Utrecht, The Netherlands,
2000.
9
8792 J. AM. CHEM. SOC. VOL. 128, NO. 27, 2006