3938 Organometallics, Vol. 17, No. 18, 1998
Xie et al.
P r ep a r a tion of [Cp ′′2Gd F ]2 (4). To a mixture of Cp′′3Gd
(0.237 g, 0.30 mmol) and Me3NHF (0.024 g, 0.30 mmol) was
added 20 mL of THF at room temperature. The mixture was
then stirred at room temperature for 4 h, followed by proce-
dures similar to those used in the synthesis of 1, affording 4
as a white solid (0.13 g, 73%). Recrystallization from hot
hexane gave X-ray quality colorless crystals. 1H NMR (benzene-
d6): δ 6.65 (br, 2H), 1.01 (br, 1H), -0.04 (s, 18H). MS (EI, 70
eV): 981 ([M-Cp′′]+, 36), 576 ([Cp′′2Gd]+, 56), 386 ([Cp′′GdF]+,
9). IR (KBr, cm-1): ν 3084 (w), 3063 (w), 3042 (w), 2956 (s),
2897 (m), 1248 (s), 1078 (s), 923 (m), 831 (vs), 752 (s). Mp:
327-330 °C. Anal. Calcd for C44H84Si8Gd2F2: C, 44.39; H,
7.11. Found: C, 44.32; H, 7.25.
Exp er im en ta l Section
Gen er a l P r oced u r es. All experiments were performed
under an atmosphere of dry dinitrogen with the 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. Cp′′3Ln10 and Cp3Ln (Cp ) C5H5)11 were prepared
according to the literature methods. Me3NHF was prepared
from the equimolar reaction of Me3N with HF in aqueous
solution, followed by recrystallization from acetone, and then
dried at 50 °C under vacuum.9 All other chemicals were
purchased from Aldrich Chemical Co. and used as received
unless otherwise noted. Infrared spectra were obtained from
a KBr pellet prepared inside the glovebox on a Nicolet Magna
550 Fourier transform spectrometer. MS spectra were re-
corded on a Bruker APEX FTMS spectrometer. 1H and 13C
NMR spectra were recorded on a Bruker 300 MHz DPX
spectrometer at 300.13 and 75.47 MHz, respectively. All
chemical shifts are reported in δ units with reference to the
residual protons of deuterated solvent or external TMS (0.00
ppm) for proton and carbon chemical shifts. Complexometric
metal analyses were conducted by titration with EDTA.
P r ep a r a tion of [Cp ′′2La F ]2 (1). To a mixture of Cp′′3La
(1.545 g, 2.00 mmol) and Me3NHF (0.159 g, 2.00 mmol) was
added 60 mL of THF at room temperature. The suspension
was then stirred for 1 day. After removal of THF and
remaining Me3N under vacuum, the solid was extracted with
hot hexane (3 × 20 mL). The hexane solution was then
concentrated to give a white solid, which was recrystallized
from hot hexane to afford 1 as colorless crystals (0.49 g, 42%).
1H NMR (CD2Cl2): δ 6.87 (s, 1H), 6.76 (s, 2H), 0.41 (s, 18H).
1H NMR (CD2Cl2/THF): δ 6.86 (s, 1H), 6.75 (s, 2H), 0.41 (s,
18H), 3.69 (m, 4H), 1.82 (m, 4H). 13C NMR (CD2Cl2): δ 130.9,
129.2, 125.2, 0.07. MS (EI, 70 eV): 944 ([M-Cp′′]+, 49), 577
(1/2M+, 8), 557 ([Cp′′2La]+, 100), 367 ([Cp′′LaF]+, 27). IR (KBr,
cm-1): ν 3075 (w), 3044 (w), 2955 (s), 2897 (m), 1250 (s), 1079
(s), 921 (m), 828 (vs), 752 (s). Mp: 217-220 °C. Anal. Calcd
for C44H84Si8La2F2: C, 45.81; H, 7.34; La, 18.10. Found: C,
45.67; H, 7.22; La, 18.30.
P r ep a r a tion of [Cp ′′2Nd F ]2 (2). To a mixture of Cp′′3Nd
(0.39 g, 0.51 mmol) and Me3NHF (0.040 g, 0.51 mmol) was
added 20 mL of THF at room temperature. The mixture was
then stirred at room temperature for 4 h, followed by proce-
dures similar to those used in the synthesis of 1, affording 2
as a blue solid (0.26 g, 89%). Recrystallization from hot hexane
gave X-ray quality blue crystals. 1H NMR (benzene-d6): δ
29.48 (br, 1H), 15.11 (br, 2H), -8.65 (s, 18H). MS (EI, 70 eV):
949 ([M-Cp′′]+, 2), 740 ([M-2Cp′′]+, 2), 560 ([Cp′′2Nd]+, 2), 370
([Cp′′NdF]+, 5). IR (KBr, cm-1): ν 3079 (w), 3054 (w), 2955
(s), 2897 (m), 1249 (s), 1078 (s), 921 (m), 823 (vs), 753 (s).
Mp: 269-270 °C. Anal. Calcd for C44H84Si8Nd2F2: C, 45.39;
H, 7.27. Found: C, 44.78; H, 7.35.
P r ep a r a tion of [Cp ′′2Sm F ]2 (3). To a mixture of Cp′′3Sm
(2.00 g, 2.57 mmol) and Me3NHF (0.204 g, 2.58 mmol) was
added 100 mL of THF at room temperature. The mixture was
then stirred at room temperature for 1 day, followed by
procedures similar to those used in the synthesis of 1, affording
3 as yellow crystals (1.10 g, 73%). 1H NMR (benzene-d6): δ
21.64 (s, 1H), 17.10 (s, 2H), -2.20 (s, 18H). MS (EI, 70 eV):
969 ([M-Cp′′]+, 4), 589 (1/2M+, 2), 570 ([Cp′′2Sm]+, 100), 361
([Cp′′Sm]+, 18). IR (KBr, cm-1): ν 3082 (w), 2955 (s), 2898
(m), 1437 (m), 1318 (m), 1247 (s), 1077 (s), 921 (s), 832 (vs),
782 (s). Mp: 218-220 °C. Anal. Calcd for C44H84Si8Sm2F2:
C, 44.91; H, 7.20; Sm, 25.56. Found: C, 44.45; H, 7.19, Sm,
25.33.
Attem p t to P r ep a r e Cp ′′Sm F 2(THF )x. To a mixture of
Cp′′3Sm (0.56 g, 0.71 mmol) and Me3NHF (0.11 g, 1.40 mmol)
was added 30 mL of THF at -30 °C with stirring. The
suspension was allowed to warm to room temperature and
stirred for 2 days. The white precipitate was filtered off (50
mg) and identified as SmF3 by XPS. The pale yellow solution
was then concentrated, and hexane vapor diffusion afforded a
pale yellow solid. This solid was first extracted with hexane
(3 × 10 mL) and then with THF (3 × 10 mL). The residue
was identified as SmF3 (80 mg). Concentration of the hexane
solution gave a yellow solid (70 mg), identified as 3 by MS
1
and H NMR. Concentration of the THF solution and hexane
vapor diffusion yielded a pale yellow solid again which is a
mixture of SmF3, 3, and other unidentified compounds.
P r ep a r a tion of [Cp 2YF (THF )]2 (5). To a mixture of
Cp3Y(THF) (0.28 g, 0.79 mmol) and Me3NHF (0.063 g, 0.79
mmol) was added 30 mL of THF at room temperature. The
suspension was then stirred at room temperature for 4 days,
at which time it became a homogeneous solution. Removal of
half of the solvent and cooling to -30 °C gave 5 as colorless
crystals after several days. The second crop of crystals was
collected after further concentration of the mother liquor. The
1
total yield of the colorless crystals was 0.17 g (69% yield). H
NMR (pyridine-d5): δ 6.09 (s, 10H), 3.63 (t, 4H), 1.59 (m, 4H).
13C NMR (pyridine-d5): δ 132.0, 67.6, 25.9. The MS of 5
showed the presence of THF in the early scans (<120 °C) and
above 280 °C unsolvated ions with a maximum m/z of 649
(Cp5Y3F3+, 62), along with a series of fragments containing one,
two, and three yttrium atoms, suggesting the formation of
trimer (Cp2YF)3 in the gas phase. MS (EI, 70 eV): 649 ([(Cp2-
YF)3 - Cp]+, 62), 476 ([M-2THF]+, 5), 411 ([M-2THF - Cp]+,
20), 219 ([Cp2Y]+, 100), 173 ([CpYF]+, 10). IR (KBr, cm-1): ν
3090 (m), 2965 (s), 2894 (s), 1639 (m), 1459 (m), 1261 (m), 1015
(s), 872 (m), 767 (vs). Anal. Calcd for C24H28F2OY2 (5 -
THF): C, 52.57; H, 5.15. Found: C, 52.27; H, 5.91. The
coordinated THF molecules can be removed under vacuum at
30 °C overnight. 1H NMR (pyridine-d5): δ 6.05 (s, 10H). The
MS spectrum of this unsolvated compound is the same as that
of 5 but with no THF fragments.
P r ep a r a tion of [Cp 2YbF (THF )]2 (6). To a mixture of Cp3-
Yb(THF) (0.19 g, 0.43 mmol) and Me3NHF (0.034 g, 0.43 mmol)
was added 30 mL of THF at room temperature. The suspen-
sion was then stirred at room temperature for several days,
at which time it became a homogeneous solution. Filtration
and slow evaporation of the clear THF solution gave 6 as
yellow crystals (0.085 g, 53%). 1H NMR (pyridine-d5): δ 6.56
(s, 10H), 3.60 (br, 4H), 1.57 (br, 4H). MS (EI, 70 eV): 72
(THF+, 27), 66 (C5H6+, 100), 65 (C5H5+, 52); no fragments
containing ytterbium atom were observed. IR (KBr, cm-1): ν
3092 (m), 2977 (s), 2894 (s), 1651 (m), 1458 (w), 1013 (s), 872
(m), 776 (vs). Anal. Calcd for C20H20F2Yb2 (6 - 2THF): C,
37.28; H, 3.13. Found: C, 36.72; H, 3.87.
Attem p t To P r ep a r e [Cp 2Sm F (THF )]2. To a mixture of
Cp3Sm(THF) (0.35 g, 0.83 mmol) and Me3NHF (0.065 g, 0.83
mmol) was added 30 mL of THF at room temperature. The
suspension was then stirred for several days, at which time it
became a homogeneous solution. Filtration and slow evapora-
tion of the clear THF solution at room temperature gave a
(10) Xie, Z.; Chui, K.; Liu, Z.; Xue, F.; Zhang, Z.; Mak, T. C. W.;
Sun, J . J . Organomet. Chem. 1997, 549, 239.
(11) (a) Wilkinson, G.; Birmingham, J . M. J . Am. Chem. Soc. 1954,
76, 6210. (b) Birmingham, J . M.; Wilkinson, G. J . Am. Chem. Soc. 1956,
78, 42.