Aminobis(phenolate)Lanthanocenes
923
titration with a xylenol orange indicator and a hexamine Synthesis of LYbCp(THF)2 (3)
buffer. Carbon, hydrogen and nitrogen analyses were per-
The synthesis of complex 3 was carried out in the similar way
as that described for complex 1, except that Cp3Yb (method
A) or YbCl3 (method B) was used instead of Cp3Sm or
SmCl3. Yellow microcrystals of complex 3 were obtained
from a concentrated THF solution at –20ꢀC over a few days
in yields of 63.2% and 71.2% (based on Yb), respectively. M.
p. (dec.): 128ꢀC. Anal. Calcd for C48H77N2O4Yb: C, 62.76;
H, 8.38; N, 3.05; Yb, 18.83. Found: C, 62.33; H, 8.20; N,
3.24.; Yb, 18.65. IR (KBr, cm-1): 3422(m), 3139(s), 2956(s),
2867(m), 2373(w), 2346(w), 1635(m), 1477(s), 1439(s), 1400
(s), 1362(m), 1306(m), 1238(m), 1202(w), 1166(w), 1133(w),
878(w), 836(w), 744(w), 528(w), 443(w). The crystals suitable
for X-ray diffraction analysis were acquired from the concen-
trated THF/DME solution.
formed by direct combustion with a Carlo-Erba EA-1110
instrument. The IR spectra were recorded with a Perkin
Elmer Spectrum BXII spectrometer as KBr pellets. The melt-
ing points of crystalline samples were determined in sealed
capillaries (under argon) and uncorrected.
Synthesis of LSmCp(THF)2 (1)
Method A
To a THF solution (about 25 mL) of Cp3Sm (2.10 mmol), pre-
pared in situ from anhydrous SmCl3 (0.533 g, 2.10 mmol) and
CpNa (6.30 mmol) in THF, a THF solution of LH2 (1.136 g,
2.1 mmol) was added. The reaction mixture was stirred for 24 h
at room temperature, and then centrifugalized to remove the
insoluble NaCl. The obtained clear yellow solution was concen-
trated by evaporating the solvent under reduced pressure, and
then stored at –20ꢀC. Colorless microcrystals of complex 1
(1.335 g, 71.0% based on Sm) were collected. M.p. (dec.):
157ꢀC. Anal. Calcd for C48H77N2O4Sm: C, 64.34; H, 8.59; N,
3.12; Sm, 16.78. Found: C, 63.86; H, 8.22; N, 3.46; Sm, 17.09.
IR (KBr, cm-1): 3435(s), 3152(s), 2953(s), 2867(m), 2367(w),
2346(w), 1636(m), 1476(s), 1442(s), 1402(s), 1361(m), 1299(m),
1275(m), 1237(m), 1203(w), 1168(w), 1131(w), 1032(w), 878
(w), 833(w), 766(m), 742(w), 520(w), 439(w). The crystals suit-
able for X-ray diffraction analysis were acquired from the con-
centrated THF/toluene solution.
X-Ray Crystallography
Suitable single crystals of complexes 1–3 were sealed in thin-
walled glass capillaries for determination of the structures.
Intensity data were collected with a SMART APEX-II detec-
tor in pꢀ and v scan modes using Mo Ka radiation (λ D
0.71070 A). The diffraction intensities were corrected for Lor-
entz/polarization effects and empirical absorption correc-
tions. The structure was solved by direct method with
SHELXS-97 program[17] and refined with SHELXL-97[18] by
full-matrix least squares procedures based on F2. All of the
non-hydrogen atoms were refined anisotropically. The hydro-
gen atoms in these complexes were all generated geometri-
cally, assigned appropriate isotropic thermal parameters, and
allowed to ride on their parent carbon atoms.
Method B
To a suspension of SmCl3 (0.559 g, 2.18 mmol) in 20 mL of
THF the THF solution of LNa2 (6.5 mL, 0.335 mol/L, 2.18
mmol) was added dropwise. Half an hour later, a THF solution
of CpNa (1.04 mL, 2.10 mol/L, 2.18 mmol) was added as well.
The mixture was stirred for 24 h. Precipitates were then sepa-
rated from the reaction mixture by centrifugation. The
obtained clear solution was concentrated and then stored at
–20ꢀC to produce microcrystals of complex 1 (1.618 g, 82.6%
based on Sm).
Results and Discussion
Zhou et al.[15] reported that the protonolysis of Cp3Ln with
one equivalent of L’H2 produced complexes of L’LnCp
(THF) (Ln D La, Sm) in good yields (60–74%). A similar
reaction is also applicable for Cp3Ln (Ln D Sm, Er, Yb) and
LH2. The reaction of Cp3Ln and LH2 proceeded smoothly to
produce complexes 1–3 in isolated yields of 71.0%, 74.2%,
and 63.2%, respectively. Salt metathesis reaction of anhy-
drous LnCl3 with one equivalent of LNa2 and one equivalent
of CpNa in THF successively could also afford complexes 1–
Synthesis of LErCp(THF)2 (2)
The synthesis of complex 2 was carried out in the similar way 3, and the obtained yields (82.6%, 86.8%, and 71.2%, respec-
as that described for complex 1, except that Cp3Er (method tively) were relatively higher than those in the protonolysis
A) or ErCl3 (method B) was used instead of Cp3Sm or method. Complexes 1–3 were characterized by infrared spec-
SmCl3. Pink microcrystals of complex 2 were obtained from tra, elemental analyses, and X-ray crystallography. The IR
a concentrated THF solution at –20ꢀC over a few days in absorptions around 1477 and 1635 cm–1 are consistent with
yields of 74.2% and 86.8% (based on Er), respectively. M.p. the existence of phenyl group. The synthesis routes were
(dec.): 129ꢀC. Anal. Calcd. for C48H77N2O4Er: C, 63.15; H, shown in Scheme 1, and the molecular structures of com-
8.43; N, 3.07; Er, 18.32. Found: C, 62.75; H, 8.31; N, 3.18; plexes 1–3 are depicted in Figure 1. Main crystallographic
Er, 18.28. IR (KBr, cm-1): 3400(m), 3138(m), 2956(s), 2867 data are listed in Table 1, and the selected bond distances
(m), 2367(w), 2346(w), 1625(w), 1479(s), 1444(m), 1400(m), and angles are in Table 2.
1361(m), 1305(m), 1237(m), 1203(m), 1166(w), 1132(w), 878
As shown in Figure 1, the L2– dianionic ligand in each of
(w), 836(w), 744(w), 528(w), 442(w). The crystals suitable for complexes 1–3 coordinates with the lanthanide ion via two
X-ray diffraction analysis were acquired from the concen- phenolic oxygen atoms and a bridging nitrogen atom. The
trated THF/toluene solution.
amido end group of the side arm in L2– ligand is not bonded