Synthesis, structure, and lanthanide derivatives of an unusual hexameric alcohol: [2,4,6-(CF3)3C6H2CH 2OH]6

Article abstract of DOI:10.1002/zaac.200400171

Hitherto unknown 2,4,6-tris(trifluoromethyl)benzyl alcohol (3) was synthesized in 41 % yield by treatment of freshly prepared R_FLi (2) with paraformaldehyde (R_F = 2,4,6-tris(trifluoromethyl)phenyl). According to an X-ray diffraction study the crystal structure of 3 consists of S₆ symmetric cyclic hexamers [2,4,6-(CF₃) ₃C₆H₂CH₂OH]₆. Deprotonation of 3 with NaN(SiMe₃)₂ in toluene afforded the unsolvated sodium alkoxide derivative R_FCH₂ONa (4). Homoleptic lanthanide alkoxides of the type Ln(OCH₂R _F)₃ (Ln = Nd (5), Sm (6), Yb (7)) were made by treatment of Ln(C₅H₅)₃ with three equivalents of 3. Similar reactions in a 1:1 molar ratio afforded the bis(cyclopentadienyl) lanthanide alkoxide derivatives (C₅H₅) ₂Ln(OCH₂R_F) (Ln = Nd (8), Sm (9), Yb (10)).

Full text of DOI:10.1002/zaac.200400171

Synthesis, Structure, and Lanthanide Derivatives of an Unusual Hexameric
Alcohol: [2,4,6-(CF3)3C6H2CH2OH]6
Frank T. Edelmann*,a, Peter Porembab, Frank Michael Bohnenb and Regine Herbst-Irmerb
Magdeburg, Chemisches Institut der Otto-von-Guericke-Universität
Received May 15th, 2004.
Dedicated to Professor Konrad Seppelt on the Occasion of his 60th Birthday
Abstract. Hitherto unknown 2,4,6-tris(trifluoromethyl)benzyl al-
cohol (3) was synthesized in 41 % yield by treatment of freshly pre-
pared RFLi (2) with paraformaldehyde (RF ϭ 2,4,6-tris(trifluoro-
methyl)phenyl). According to an X-ray diffraction study the crystal
structure of 3 consists of S6 symmetric cyclic hexamers [2,4,6-
(CF3)3C6H2CH2OH]6. Deprotonation of 3 with NaN(SiMe3)2 in
toluene afforded the unsolvated sodium alkoxide derivative
RFCH2ONa (4). Homoleptic lanthanide alkoxides of the type
Ln(OCH2RF)3 (Ln ϭ Nd (5), Sm (6), Yb (7)) were made by treat-
ment of Ln(C5H5)3 with three equivalents of 3. Similar reactions
in a 1:1 molar ratio afforded the bis(cyclopentadienyl)lanthanide
alkoxide derivatives (C5H5)2Ln(OCH2RF) (Ln ϭ Nd (8), Sm (9),
Yb (10)).
Keywords: methanol hexamer; fluorine; 2,4,6-tris(trifluoromethyl)-
phenyl substituent; lanthanides; cyclopentadienyl lanthanide com-
plexes; X-ray structure
Synthese, Struktur und Lanthanoidderivative eines ungewöhnlichen hexameren
Alkohols: [2,4,6-(CF3)3C6H2CH2OH]6
Inhaltsübersicht. Der bislang unbekannte 2,4,6-Tris(trifluorome-
thyl)benzylalkohol (3) wurde in 41 % Ausbeute durch Umsetzung
von frisch hergestelltem RFLi (2) mit Paraformaldehyd synthetisiert
(RF ϭ 2,4,6-Tris(trifluoromethyl)phenyl). Nach der Röntgenstruk-
turanalyse enthält die Kristallstruktur von 3 S6-symmetrische,
cyclische Hexamere [2,4,6-(CF3)3C6H2CH2OH]6. Deprotonierung
von 3 mit NaN(SiMe3)2 in Toluol lieferte das unsolvatisierte Natri-
umalkoxid RFCH2ONa (4). Homoleptische Lanthanoidalkoxide
des Typs Ln(OCH2RF)3 (Ln ϭ Nd (5), Sm (6), Yb (7)) wurden
durch Umsetzung von Ln(C5H5)3 mit drei Äquivalenten 3 erhalten.
Die gleichen Reaktionen im Molverhältnis 1:1 lieferten die Bis(cy-
clopentadienyl)lanthanoidalkoxide (C5H5)2Ln(OCH2RF) (Ln
ϭ
Nd (8), Sm (9), Yb (10)).
Introduction
lowest lying isomers of this cluster are those adopting either
S6 or C2 symmetry (Scheme 1).
The structure of methanol in different physical states has
been the subject of detailed investigations for decades. In
the crystal at Ϫ110 °C, solid methanol forms infinite zigzag
chains via hydrogen bonds [1]. The C-O distance is 1.42 A,
and the O···O distance is 2.66 A. Above the melting point
˚
˚
these infinite chains break up, and shorter chains and/or
cyclic oligomers of the type (MeOH)n with n ϭ 3-20 are
formed [2Ϫ4]. In his famous book “The Nature of the
Chemical Bond” Pauling has already illustrated the structure
of solid and liquid methanol, including the cyclic hexamer
(MeOH)6 [5]. It has later been demonstrated that this hexa-
mer is the predominant cluster species present in liquid
methanol at room temperature [6Ϫ8]. The two energetically
Scheme 1 S6 and C2 symmetric forms of hexameric methanol clus-
ters (MeOH)6.
Both isomers have been size selected by momentum
transfer in collisions with He, and identified by their IR
spectra [9]. The predominant species present in gaseous
methanol has been shown to be the cyclic tetramer
(MeOH)4 [10]. More recently, Wieghardt et al. described the
assembly of (MeOH)6 in a hydrophobic ligand cavity. X-
ray crystallography revealed the presence of the cyclic S6
symmetric methanol hexamer in crystals of [GaLF3]-
* Prof. F. T. Edelmann
Chemisches Institut der Otto-von-Guericke-Universität Magde-
burg
Universitätsplatz 2
D-39106 Magdeburg (Germany)
Fax: (ϩ49)-391-6712933
E-mail: frank.edelmann@vst.uni-magdeburg.de
(MeOH)6/2·(MeOH)3·CH2Cl2 where
L
represents the
Z. Anorg. Allg. Chem. 2004, 630, 1671Ϫ1676
DOI: 10.1002/zaac.200400171
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F. T. Edelmann, P. Poremba, F. M. Bohnen, R. Herbst-Irmer
Table 1 Crystal data for compound 3
formula
Mr
C10H5F9O
312.14
Crystal size /mm
Space group
0.40 x 0.30 x 0.30
P1
11.481(5)
12.753(5)
¯
˚
a /A
˚
b /A
˚
c /A
13.698(6)
Ͱ /°
β /°
γ /°
70.00(1)
81.18(2)
66.29(2)
1725.3(1)
3
˚
V /A
Z
6
µ /mmϪ1
0.214
Scheme 2 Preparation of 2,4,6-tris(trifluoromethyl)benzyl alcohol
(3).
␽ range /°
4.04-22.52
4000
3999 / 1305 / 554
1.033
R1 ϭ 0.0459, wR2 ϭ 0.1037
R1 ϭ 0.0553, wR2 ϭ 0.118
independent reflections
data / restraints / parameters
goodness-of-fit on F2
final R indices [I>2sigma(I)]
R indices (all data)
macrocyclic ligand 1,4,7-tris(2-amino-3,5-di-t-butylbenzyl)-
1,4,7-triazacyclononane [11]. In the present contribution we
report the synthesis and structural characterization of an
unusual methanol derivative, 2,4,6-tris(trifluoromethyl)ben-
zyl alcohol (3), which was found to adopt the cyclic S6 sym-
metric hexamer form in the solid state.
˚
Table 2 Selected bond lengths /A and angles /° of 3.
Intramolecular (one of three independent molecules in the asymmetric unit)
Since 1987 the chemistry of the 2,4,6-tris(trifluorome-
thyl)phenyl substituent (“nonafluoromesityl”, abbreviated
as RF) has been intensively investigated [12Ϫ14]. The com-
bination of steric bulk and electronic stabilization makes
this ligand an ideal choice for the stabilization of low-coor-
dinated main-group derivatives [12]. More recently, the nona-
fluoromesityl ligand has also been successfully employed in
transition metal chemistry [15Ϫ17]. However, due to severe
steric hindrance, certain purely organic RF derivatives have
been found to be inaccessible. For example, the carboxylic
acid RFC(ϭO)OH fails to undergo normal esterification
with ethanol [18], and various attempts to prepare
2,4,6-tris(trifluoromethyl)acetophenone have been unsuc-
cessful [18]. This prompted us to investigate the synthesis
of the hitherto unknown 2,4,6-tris(trifluoromethyl)benzyl
alcohol, RFCH2OH.
C(1)-C(6)
C(3)-C(4)
C(5)-C(4)
C(10)-O(1)
C(2)-C(1)-C(6)
C(6)-C(1)-C(10)
C(4)-C(5)-C(6)
C(5)-C(4)-C(3)
O(1)-C(10)-C(1)
1.403(6)
1.379(6)
1.374(6)
140.8(6)
117.2(4)
121.7(4)
120.8(4)
119.6(4)
108.8(4)
C(1)-C(10)
C(3)-C(2)
C(5)-C(6)
1.520(7)
1.388(6)
1.391(6)
C(2)-C(1)-C(10)
C(4)-C(3)-C(2)
C(3)-C(2)-C(1)
C(5)-C(6)-C(1)
121.1(5)
120.2(4)
121.3(4)
120.8(4)
Intermolecular
O···O (ave.)
2.647
O2b···O1a···O3a, O2a···O1b···O3b
O1b···O2a···O3a, O1a···O2b···O3b
O2a···O3a···O1a, O2b···O3b···O1b
111.5
118.3
119.1
colorless X-ray quality single-crystals (cubes). The com-
pound crystallizes in the triclinic space group P1(Ϫ). The
structure of an isolated molecule of 3 is depicted in Figure
1, and Figure 2 shows the structure of a hexameric unit.
Crystal data and selected bond lengths and angles are listed
in Tables 1 and 2, respectively.
Bond lengths and angles in an isolated RFCH2OH mol-
ecule are all within the normal range. The most striking
structural feature of the crystal structure of 3 is the presence
of hexameric aggregates [2,4,6-(CF3)3C6H2CH2OH]6. Six
RFCH2OH molecules form a cyclic structure through six
O-H···O hydrogen bonding interactions. The average O···O
Results and Discussion
It was found that 2,4,6-tris(trifluoromethyl)benzyl alcohol
(3) can be obtained by treatment of freshly prepared RFLi
(2) with a slight excess of paraformaldehyde (Scheme 2).
RFLi (2) is readily accessible by direct metalation of the
parent fluorocarbon using n-butyllithium. Addition of
(CH2O)n to a solution of 2 in diethylether/hexane caused a
vigorous reaction to occur after an induction period of ca.
10 min. In the course of this reaction complete dissolution
of the suspended paraformaldehyde was observed. Stand-
ard work-up afforded 3 in 41 % yield as a waxy, low-melt-
ing, crystalline solid exhibiting a pleasant aromatic odor.
Analytical and spectroscopic characterization of 3 was
straightforward and unambiguous. In the 19F NMR spec-
trum the ortho- and para-CF3 groups give rise to resonances
at δ Ϫ59.1 and Ϫ63.9, respectively, in an intensity ratio of
2:1. The most remarkable finding is the presence of a hexa-
meric structure of 3 in the crystal. Slow cooling of a satu-
rated solution of 3 in diethyl ether to Ϫ20 °C afforded large,
˚
distance is 2.647 A. This value compares favorably with that
reported by Wieghardt for the methanol hexamer found in
[GaLF3](MeOH)6/2·(MeOH)3·CH2Cl2 (O···O 2.62(1) A)
˚
[11]. In both hexamers the cyclic structures adopt S6 sym-
metry as shown in Scheme 1. Already in 1979 Saenger
pointed out the general importance of circularly arranged
hydrogen bonds [19]. Three types of such circular hydrogen
bonds can be distinguished: Those pointing all in the same
direction are called homodromic, while those pointing regu-
larly in opposite directions are called antidromic. Heterod-
romic hydrogen bonds are not ordered. In the case of 3 a
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Z. Anorg. Allg. Chem. 2004, 630, 1671Ϫ1676

Lanthanide Derivatives of an Unusual Hexameric Alcohol: [2,4,6-(CF3)3C6H2CH2OH]6
sodium alkoxide derivative is readily prepared according to
Scheme 3 by the reaction of 3 with NaN(SiMe3)2 in toluene
solution. Under these conditions RFCH2ONa (4) can be
isolated as a white, moisture-sensitive powder in 72 % yield.
The product is soluble in hot toluene, while coordinating
solvents like THF or acetonitrile lead to rapid decompo-
sition (formation of red or brown solutions). Analytical and
spectroscopic data of 4 are in agreement with the presence
of an unsolvated sodium alkoxide of presumably polymeric
or oligomeric structure. As for the parent alcohol, the 19F
NMR spectrum of 4 displays two singlets at δ Ϫ60.5 and
Ϫ63.3 ppm, which can be assigned to the ortho- and para-
CF3 groups, respectively (intensity ratio 2:1).
A possible synthetic route to lanthanide alkoxides in-
volves salt-elimination reactions between anhydrous lantha-
nide trichlorides and alkali metal alkoxides in an appropri-
ate organic solvent. However, a characteristic feature of this
type of preparations is the formation of so-called “ate-com-
plexes” in which the resulting alkali metal halides are par-
tially retained and incorporated in the molecular structures
[20]. In order to circumvent this possible complication, we
chose a salt-free synthetic route to prepare homoleptic lan-
thanide alkoxides derived from 3. The method involves pro-
tonation of all three cyclopentadienyl ligands in Ln(C5H5)3
(Ln ϭ Nd, Sm, Yb) by three equivalents of 3 in toluene
solution according to Scheme 4.
Figure 1 Structure of one molecule of 3.
difference electron density map of the crystal structure
clearly showed a homodromic arrangement of the hydrogen
bonds within the twelve-membered ring system of hexa-
meric [2,4,6-(CF3)3C6H2CH2OH]6.
We also report here an initial study of the derivative
chemistry of 3, thereby focussing on its function as an ancil-
lary ligand in (organo)lanthanide chemistry. An unsolvated
Rapid reactions were observed in boiling toluene. After
ca. 30 min the color of the lanthanide starting material had
disappeared in all three cases. Recrystallization of the crude
Figure 2 Molecular structure of the cyclic hexamer [2,4,6-(CF3)3C6H2CH2OH]6.
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F. T. Edelmann, P. Poremba, F. M. Bohnen, R. Herbst-Irmer
Scheme 3 Preparation of RFCH2ONa (4).
Scheme 5 Preparation of the complexes (C5H5)2Ln(OCH2RF)
(8؊10).
NMR spectra. All signals are paramagnetically shifted un-
der the influence of the central lanthanide ions. For ex-
ample, the cyclopentadienyl resonances are observed as sin-
glets at δ ϭ 3.17 (8), 12.54 (9) and Ϫ33.59 (10).
Conclusion
Scheme 4 Synthesis of the lanthanide(III) aryloxides 4-6.
In summarizing these results we have developed a straight-
forward, one-pot synthetic route leading to the hitherto un-
known fluorinated alcohol 2,4,6-tris(trifluoromethyl)benzyl
alcohol (3). In the crystal, 3 forms an S6 symmetric cyclic
hexamer of the type [2,4,6-(CF3)3C6H2CH2OH]6. Initial
studies on the derivative chemistry of 3 have demonstrated
that this compound is a valuable precursor for the synthesis
of novel alkali metal and lanthanide alkoxides. It can easily
be anticipated that it will be a versatile ligand for other
main group and transition metals as well.
products from n-hexane afforded the unsolvated lanthanide
alkoxides 4-6 in low to moderate yields (22-50 %). 1H NMR
spectra showed only signals attributable to the RFCH2OϪ
ligands, thus confirming the complete elimination of all
three cyclopentadienyl ligands and formation of homoleptic
alkoxides. Although Scheme 4 depicts these compounds as
monomeric species, a dimeric or even higher oligomeric
structure cannot be ruled out, as no X-ray quality crystals
could be grown thus far and conventional molecular weight
determinations were precluded due to the high air-sensi-
tivity of 4-6. However, the mass spectra did not exhibit any
peaks corresponding to dimers, oligomers or fragments
thereof, so that the monomeric tricoordinate structure ap-
pears plausible.
Organolanthanide derivatives containing the new alkox-
ide ligand have also been found to be readily accessible via
the same synthetic route with the starting materials being
employed in a 1:1 molar ratio (Scheme 5).
The reactions depicted in Scheme 5 were carried out in
THF solution at room temperature in order to ensure elim-
ination of only one cyclopentadienyl ligand and formation
of the monoalkoxide complexes 8-10. These were isolated
in moderate yields (30-65 %) as blue (8) or orange (9, 10)
air-sensitive crystals, which are soluble in THF and toluene,
but poorly soluble in n-hexane. The composition of the
compounds as shown in Scheme 5 was proven by elemental
analyses and spectroscopic data. In the case of 8 and 9 res-
Experimental Section
General Procedures. The reactions were carried out in an atmos-
phere of dry nitrogen with the use of standard Schlenk techniques.
Solvents were dried over Na/benzophenone and freshly distilled un-
der nitrogen prior to use. IR spectra were recorded on a Perkin
Elmer FT-IR Spectrometer System 2000. NMR spectra were re-
corded on a Bruker DPX 400 NMR spectrometer (1H 400.13 MHz,
13C 101.62 MHz, 29Si 79.49 MHz). Chemical shifts are reported in
ppm and referenced to residual solvent resonances (1H, 13C) or an
internal standard (1H, 29Si: TMS ϭ 0 ppm). Elemental analyses
were performed at the Chemistry Department of the Otto-von-
Guericke-Universität using a Leco CHNS 932 apparatus. Melting
and decomposition points were measured on a Electrothermal IA
9100 apparatus. X-ray data collection and structure refinement:
The measurement on 3 was performed on a Siemens SMART CCD
˚
system with MoKα radiation (λ ϭ 0.71073 A) and graphite mono-
chromator. Selected crystals of 3 were mounted on a glass fiber
and transferred to the cold nitrogen stream (Siemens LT-2 attach-
ment). Full hemispheres of the reciprocal space were scanned by ω
in three sets of frames of 0.3°. The SADABS routine was applied
1
onances due to coordinated THF are clearly seen in the H
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Lanthanide Derivatives of an Unusual Hexameric Alcohol: [2,4,6-(CF3)3C6H2CH2OH]6
as an absorption correction. For structure solution and refinement
the programs SHELXS86 and SHELXL97 were used [21, 22]. The
compounds 1,3,5-(CF3)3C6H3 [14], RFLi [13, 14], NaN(SiMe3)2
[23], and Ln(C5H5)3 (Ln ϭ Nd, Sm, Yb) [24] were prepared accord-
ing to literature procedures.
71 °C. Elemental analysis calcd (%) for C30H12F27NdO3 (1078.55):
C 35.0, H 1.2; found: C 33.7, H 1.7.
1H NMR (25 °C, CD3CN): δ ϭ 8.74 (br, ν1/2 ϭ 72 Hz, 12H, C6H2
ϩ
CH2) ppm. 19F{1H} NMR (25 °C, CD3CN): δ ϭ Ϫ61.8 (s, 9F, p-CF3), Ϫ63.8
(br, ν1/2 ϭ 140 Hz, 18F, o-CF3) ppm. MS (EI, 70 eV): m/z 377 (NdOCH2RF
Ϫ CF3CO, 1 %), 291 (RFCH2O Ϫ F, 18 %), 263 (RF Ϫ F, 100 %), 244 (RF
Ϫ 2F, 30 %), 195 (RF ϩ H Ϫ CF4, 48 %). IR (KBr): 1635 s, 1598 s, 1304 vs,
2,4,6-Tris(trifluoromethyl)benzyl alcohol (3): In a 500 ml flask
equipped with a reflux condenser, paraformaldehyde (6.60 g,
220 mmol) was added in one portion to a freshly prepared solution
of RFLi (2, 200 mmol) in diethylether/hexane (ca. 150 ml). After
an induction period of ca. 10 min a vigorous reaction occurred,
causing to reaction mixture to reflux. Stirring at reflux temperature
was continued for 15 h. After cooling to room temperature 1M
H2SO4 (120 ml) was added, the organic layer was separated and
the aqueous layer was extracted with diethylether (4 x 70 ml). The
combined extracts were dried over anhydrous MgSO4. Diethylether
and hexane were distilled off at atmospheric pressure and the crude
product was purified by vacuum-distillation (83-87 °C / 13 torr) to
afford 25.51 g (41 %) 3 in the form of a colorless, low-melting solid.
M. p. 50 °C. Elemental analysis calcd (%) for C10H5F9O (312.13):
C 38.5, H 1.6; found: C 38.6, H 1,8.
1279 vs, 1261 vs, 1202 vs, 1127 vs, 917 s, 687 s cmϪ1
.
Tris[2,4,6-tris(trifluoromethyl)phenylmethoxy]samarium(III)
(6):
0.889 g (50 %) orange crystals of 6 were isolated from 3 (1.707 g,
4.92 mmol) and Sm(C5H5)3 (0.567, 1.64 mmol). M.p. 156 °C (dec.).
elemental analysis calcd (%) for C30H12F27O3Sm (1083.76): C 33.3,
H 1.1; found: C 32.9, H 1.8.
1H NMR (25 °C, THF-d8): δ ϭ 7.49 Ϫ 7.60 (m, 4H, C6H2 ϩ CH2), 7.26 Ϫ
7.37 (m, 8H, C6H2 ϩ CH2) ppm. 19F{1H} NMR (25 °C, CD3CN): δ ϭ Ϫ57.7
Ϫ Ϫ58.7 (m, 18F, o-CF3), Ϫ62.5 Ϫ Ϫ64.8 (m, 9F, p-CF3) ppm. MS (EI,
70 eV): m/z 295 (RFCH2, 14 %), 291 (RFCH2O Ϫ F, 17 %), 273 (RFCH2O
Ϫ 2F, 100 %), 263 (RF Ϫ F, 98 %), 244 (RF Ϫ 2F, 38 %), 195 (RF ϩ H Ϫ
CF4, 68 %). IR (KBr): 1635 s, 1598 s, 1301 vs, 1278 vs, 1203 vs, 1135 vs, 917 s,
686 s, 526 m, 495 m, 463 m cmϪ1
.
Tris[2,4,6-tris(trifluoromethyl)phenylmethoxy]ytterbium(III)
(7):
The reaction of 3 (1.707 g, 4.92 mmol) with Yb(C5H5)3 (0.671 g,
1.64 mmol) afforded 0.399 g (22 %) 7 as beige-colored crystals.
M.p. 193 °C (dec.). Elemental analysis calcd (%) for
C30H12F27O3Yb (1106.44): C 32.6, H 1.1; found: C 31.3, H 1.3.
1H NMR (25 °C, CDCl3): δ ϭ 8.13 (s, 2H, C6H2), 4.96 (s, 2H, CH2), 2.13
(br, 1H, ν1/2 ϭ 35 Hz, OH) ppm. 13C NMR (25 °C, CDCl3): δ ϭ 141.4 (qqq,
3J3(13C-19F) ϭ 1.1 Hz, 3J4(13C-19F) ϭ 1.1 Hz, 5J2(13C-19F) ϭ 1.1 Hz, ipso-
C6H2), 132.8 (q, 2J(13C-19F) ϭ 31.5 Hz, o-C6H2), 131.5 (q, 2J(13C-19F) ϭ
31.5 Hz, p-C6H2), 127.2 (qqq, 3J1(13C-19F) ϭ 3.7 Hz, 3J2(13C-19F) ϭ 2.3 Hz,
5J1(13C-19F) ϭ 1.0 Hz, m-C6H2), 123.0 (q, 1J(13C-19F) ϭ 102.2 Hz, o-CF3),
122.5 (q, 1J(13C-19F) ϭ 102.2 Hz, p-CF3), 56.8 (sept, 4J1(13C-19F) ϭ 2.5 Hz,
CH2) ppm. 19F{1H} NMR (25 °C, CDCl3): δ ϭ Ϫ59.1 (s, 6F, o-CF3), Ϫ63.9
(s, 3F, p-CF3) ppm. MS (EI, 70 eV): m/z 295 (M Ϫ OH, 10 %), 263 (M Ϫ F
Ϫ CH2OH, 23 %), 241 (RF Ϫ 2HF, 100 %), 69 (CF3, 8 %). IR (KBr): 3200 s,
1H NMR (25 °C, CD3CN): δ ϭ 8.22 (br, ν1/2 ϭ 42 Hz, 6H C6H2), 4.85 (br,
6H, CH2) ppm. 19F{1H} NMR (25 °C, CD3CN): δ ϭ Ϫ57.8 (br, ν1/2 ϭ 30 Hz,
18F, o-CF3), Ϫ62.4 (br, ν1/2 ϭ 30 Hz, 9F, p-CF3) ppm. MS (EI, 70 eV): m/z
295 (RFCH2, 12 %), 291 (RFCH2O Ϫ F, 27 %), 263 (RF Ϫ F, 100 %), 244
(RF Ϫ 2 F, 60 %). IR (KBr): 1634 s, 1295 vs, 1278 vs, 1204 vs, 1131 vs, 919 s,
687 s, 554 m, 533 m, 518 m, 494 m cmϪ1
.
1743 s, 1636 s, 1601 s, 1278 vs, 1295 vs, 1130 vs, 920 s, 686 s, cmϪ1
.
Bis(η5-cyclopentadienyl)(tetrahydrofuran)[2,4,6-tris(trifluoromethyl)-
phenylmethoxy]neodymium(III) (8): solution of Nd(C5H5)3
Sodium [2,4,6-tris(trifluoromethyl)phenyl]methoxide (4): RFCH2OH
(1, 9.36 g, 30 mmol) was added as a solid to a solution of NaN-
(SiMe3)2 (5.50 g, 30 mmol) in toluene (120 ml), and the mixture
was stirred for 15 h at room temperature. Precipitation of white,
microcrystalline 4 commenced after ca. 1 h. After removal of all
volatile materials in vacuo the residue was washed with n-hexane
(50 ml) and isolated by filtration. Drying under vacuum afforded
7.26 g (72 %) 4 as a moisture-sensitive, white solid, which decom-
poses at 130 °C. Elemental analysis calcd (%) for C10H4F9ONa
(334.12): C 36.0, H 1.2; found: C 35.2, H 1,6.
A
(1.230 g, 3.83 mmol) and 3 (1.195 g, 3.83 mmol) in THF (100 ml)
was stirred at room temperature until the starting materials had
completely dissolved (ca. 1 h). The reaction mixture was evaporated
to dryness. Washing of the residue with n-hexane (70 ml) and dry-
ing in vacuo afforded 0.578 g (30 %) of 8 as a pale blue, microcrys-
talline solid. Elemental analysis calcd (%) for C24H22F9NdO2
(657.68): C 43.8, H 3.4; found: C 41.8, H 3.4.
1H NMR (25 °C, CD3CN): δ ϭ 9.54 (br, ν1/2 ϭ 44 Hz, 2H, C6H2), 3.61 (m,
4H, THF-OCH2), 3.17 (br, ν1/2 ϭ 33 Hz, 10H, C5H5), 1.79 (m, 4H, THF-
CH2), Ϫ2.62 (br, ν1/2 ϭ 66 Hz, 2H, CH2) ppm. 19F{1H} NMR (25 °C,
CD3CN): δ ϭ Ϫ55.2 (br, ν1/2 ϭ 105 Hz, 6F, o-CF3), Ϫ61.8 (s, 3F, p-
CF3) ppm. IR (KBr): 1653 s, 1633 s, 1596 s, 1311 vs, 1280 vs, 1271 vs,
1H NMR (25 °C, CDCl3): δ ϭ 7.93 (s, 2H, C6H2), 4.79 (s, 2H, CH2) ppm.
19F{1H} NMR (25 °C, C6D6): δ ϭ Ϫ60.5 (s, 6F, o-CF3), Ϫ63.3 (s, 3F, p-
CF3) ppm. MS (EI, 70 eV): m/z 832 (2M ϩ C6H3CF2 ϩ O, 5 %), 565 (M ϩ
Na ϩ F3CC6H4CO2, 35 %), 549 (M ϩ Na ϩ F3CC6H4CO, 22 %), 295
(RFCH2, 100 %), 263 (RF Ϫ F Ϫ CH2O, 37 %, 241 (RF Ϫ 2HF, 40 %), 195
(RF ϩ H Ϫ CF4, 10 %). IR (KBr): 1633 s, 1596 s, 1293 vs, 1279 vs, 1270 vs,
1144 vs, 917 s, 861 w, 687 s cmϪ1
.
Bis(η5-cyclopentadienyl)(tetrahydrofuran)[2,4,6-tris(trifluoromethyl)-
phenylmethoxy]samarium(III) (9): A similar reaction of Sm(C5H5)3
(0.567 g, 1.64 mmol) and 3 (0.512 g, 1.64 mmol) gave 0.709 g
(65 %) 9 as orange crystals. Elemental analysis calcd (%) for
C24H22F9O2Sm (663.80): C 43.4, H 3.3; found: C 44.0, H 3.7.
1202 vs, 1135 vs, 919 s, 687 s cmϪ1
.
Synthesis of tris[2,4,6-tris(trifluoromethyl)phenylmethoxy]lanthani-
des(III) (5-7)
(General Procedure)
1H NMR (25 °C, CD3CN): δ ϭ 12.54 (s, 10H, C5H5), 8.64 (s, 2H, C6H2),
Three equivalents of RFCH2OH (3) were added as a solid to a
suspension of tris(cyclopentadienyl)lanthanide(III) in toluene
(70 ml). The reaction mixture was heated to reflux and stirred for
30 min, whereby the lanthanide precursors dissolved completely.
All volatiles were removed under vacuum, and the oily residue was
extracted with boiling n-hexane (70 ml). The extract was filtered
through a thin layer of Celite filter aid and concentrated to a total
volume of ca. 35 ml. Standing at room temperature for 24 h af-
forded the crystalline product which was isolated by filtration and
drying in vacuo.
8.53 (br, ν1/2 ϭ 58 Hz, 2H, CH2), 3.64 (m, 4H, THF-OCH2), 1.80 (m, 4H,
THF-CH2) ppm. 19F{1H} NMR (25 °C, CD3CN): δ ϭ Ϫ56.4 (br, ν1/2
ϭ
40 Hz, 6F, o-CF3), Ϫ62.1 (s, 3F, p-CF3) ppm. IR (KBr): 1635 s, 1595 s,
1303 vs, 1279 vs, 1261 vs, 1201 vs, 917, 862 w, 686 s cmϪ1
.
Bis(η5-cyclopentadienyl)(tetrahydrofuran)[2,4,6-tris(trifluoromethyl)-
phenylmethoxy]ytterbium(III) (10): Treatment of Yb(C5H5)3
(0.608 g, 1.65 mmol) with 3 (0.518 g, 1.65 mmol) afforded 0.601 g
(53 %) 10 in the form of orange crystals. Elemental analysis calcd
(%) for C24H22F9O2Yb (686.46): C 42.0, H 3.2; found: C 40.3, H
3.2.
Tris[2,4,6-tris(trifluoromethyl)phenylmethoxy]neodymium(III) (5):
0.636 g (36 %) light blue crystals of 5 were obtained from 3
(1.707 g, 4.92 mmol) and Nd(C5H5)3 (0.557 g, 1.64 mmol). M.p.
1H NMR (25 °C, CD3CN): δ ϭ Ϫ0,54 (s, 2H, C6H2), Ϫ0,97 (br, 2H, CH2),
Ϫ33.59 (br, ν1/2 ϭ 444 Hz, 10H, C5H5) ppm (THF signals not observed).
19F{1H} NMR (25 °C, CD3CN): δ ϭ Ϫ63.7 (br, ν1/2 ϭ 120 Hz, 6F, o-CF3),
Z. Anorg. Allg. Chem. 2004, 630, 1671Ϫ1676
zaac.wiley-vch.de
 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
1675

F. T. Edelmann, P. Poremba, F. M. Bohnen, R. Herbst-Irmer
Ϫ67.9 (s, 3F, p-CF3) ppm. IR (KBr): 1624 s, 1568 s, 1301 vs, 1280 vs, 1262 vs,
1191 vs, 1136 vs, 915 s, 860 m, 683 s, 522 s cmϪ1
[10] W. Weltner, Jr., K. S. Pitzer, J. Am. Chem. Soc. 1951, 73, 2606.
[11] F. N. Penkert, T. Weyhermüller, K. Wieghardt, J. Chem. Soc.,
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[12] F. T. Edelmann, Comments Inorg. Chem. 1992, 12, 259 and
references cited therein.
.
Acknowledgements. Financial support of this work through the
Fonds der Chemischen Industrie and the Otto-von-Guericke-Uni-
versität Magdeburg are gratefully acknowledged.
[13] G. E. Carr, R. D. Chambers, T. F. Holmes, D. G. Parker, J.
Organomet. Chem. 1987, 325, 13.
[14] M. Scholz, H. W. Roesky, D. Stalke, K. Keller, F. T. Edelmann,
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J. W. Yao, Polyhedron 1996, 15, 4173.
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Clegg, M. R. J. Elsegood, J. Chem. Soc., Chem. Commun.
1996, 2151.
Supporting Information Available: Crystallographic data (excluding
structure factors) for the structure reported in this paper have been
deposited with the Cambridge Crystallographic Data Center as
supplementary publication no. CCDC 246643. Copies of the data
can be obtained free of charge on application to CCDC, 12 Union
Road, Cambridge CB21EZ, UK (fax: (ϩ44)1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk).
[17] V. C. Gibson, C. Redshaw, W. Clegg, M. R. J. Elsegood, Poly-
hedron 1997, 16, 2637.
[18] R. Filler, W. K. Gnandt, W. Chen and S. Lin, J. Fluorine
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 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
zaac.wiley-vch.de
Z. Anorg. Allg. Chem. 2004, 630, 1671Ϫ1676