Rare-earth metal allyl and hydrido complexes supported by an (NNNN)-type macrocyclic ligand: Synthesis, structure, and reactivity toward biomass-derived furanics

Article abstract of DOI:10.1002/chem.201102145

The preparation and characterization of a series of neutral rare-earth metal complexes [Ln(Me₃TACD)(η³-C₃H ₅)₂] (Ln=Y, La, Ce, Pr, Nd, Sm) supported by the 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane anion (Me₃TACD ^-) are reported. Upon treatment of the neutral allyl complexes [Ln(Me₃TACD)(η³-C₃H₅) ₂] with Bronsted acids, monocationic allyl complexes [Ln(Me₃TACD)(η³-C₃H₅)(thf) ₂][B(C₆X₅)₄] (Ln=La, Ce, Nd, X=H, F) were isolated and characterized. Hydrogenolysis gave the hydride complexes [Ln(Me₃TACD)H₂]_n (Ln=Y, n=3; La, n=4; Sm). X-ray crystallography showed the lanthanum hydride to be tetranuclear. Reactivity studies of [Ln(Me₃TACD)R₂]_n (R=η³-C₃H₅, n=0; R=H, n=3,4) towards furan derivatives includes hydrosilylation and deoxygenation under ring-opening conditions.

Full text of DOI:10.1002/chem.201102145

DOI: 10.1002/chem.201102145
Rare-Earth Metal Allyl and Hydrido Complexes Supported by an (NNNN)-
Type Macrocyclic Ligand: Synthesis, Structure, and Reactivity toward
Biomass-Derived Furanics
Elise Abinet, Daniel Martin, Sabine Standfuss, Heiko Kulinna, Thomas P. Spaniol, and
[
a]
Jun Okuda*
3
Abstract: The preparation and charac-
complexes [Ln
A
H
U
G
E
N
N
(Me TACD)
A
T
N
T
E
N
N
(h -C H )-
n=3; La, n=4; Sm). X-ray crystallog-
3
3
5
terization of a series of neutral rare-
A
H
U
G
R
N
U
G
A
H
U
G
R
N
N
raphy showed the lanthanum hydride
2
6
5 4
earth
metal
complexes
[Ln-
H, F) were isolated and characterized.
Hydrogenolysis gave the hydride com-
to be tetranuclear. Reactivity studies of
3
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me TACD)
A( h -C H ) ] (Ln=Y, La,
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[Ln
A
H
U
G
R
N
U
G
3
3
5
2
3
2
n
3
5
Ce, Pr, Nd, Sm) supported by the 1,4,7-
plexes [Ln
A
H
U
G
R
N
U
G
0; R=H, n=3,4) towards furan deriva-
tives includes hydrosilylation and deox-
ygenation under ring-opening condi-
tions.
3
2 n
trimethyl-1,4,7,10-tetraazacyclodode-
À
cane anion (Me TACD ) are reported.
3
Keywords: allyl ligands
deoxygenation · hydrosilylation ·
lanthanides · macrocyclic ligands
Upon treatment of the neutral allyl
3
complexes [Ln
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me TACD)
A
T
N
T
E
N
N
(h -C H ) ]
3
3
5 2
with Brønsted acids, monocationic allyl
À
Introduction
Me TACD coordinates facially at trivalent rare-earth
3
metals and shields one hemisphere of the large metal cen-
[7a,b]
Lignocellulosic biomass from wood or paper waste is a re-
newable carbon-neutral source of energy, which does not
compete with food production such as corn or sugar cane
ter.
earth metals [Ln
CH SiMe , n=1 or Ln=Y, Ho, Lu, R=H, n=3) catalyze
Alkyl and hydrido complexes of the smaller rare-
AHCTUNGTRENNUNG
(Me TACD)R ] (Ln=Sc, Y, Ho, Lu, R=
3
2 n
2
3
[1]
[7a,b]
and could reduce societyꢀs dependence on petroleum.
the hydrosilylation of a-olefins.
Heavy lanthanides are
Lignocellulosic biomass is separated into its three main con-
stituents: 40–80% cellulose, 15–30% hemicellulose, and 10–
rare and expensive for technical applications, whereas the
natural abundance of the lighter lanthanides, especially of
the most abundant rare-earth metal cerium, has motivated
[1b]
[9]
25% lignin.
Subsequent acid treatment of hemicellulose
leads to pentoses, which can be transformed into furfural
us to use these metals. A further modification is the replace-
ment of the thermally labile trimethylsilylmethyl ligand by
[2]
with sulfuric acid. Dehydration of glucose from cellulose
[3]
3
gives 5-hydroxymethylfurfural (HMF), but furfural and its
derivatives are not suitable as fuels for combustion engines.
Hence, further transformations are needed to obtain the
allyl ligands h -C H that can stabilize large rare-earth
3
5
[10]
metals.
[1,4]
next generation of biofuels.
Highly Lewis acidic rare-
earth metal complexes hold promise as new catalysts for the
conversion of furanics. We describe here the synthesis and
characterization of rare-earth metal complexes supported by
Results and Discussion
Ligand synthesis: All reported synthetic pathways to the
proligand (Me TACD)H (LH) are tedious and low-yielding
procedures. We have now developed a two-step synthesis
with an overall yield of 72% starting from commercially
available cyclen (Scheme 1). In the first step, 1,4,7-triformyl-
cyclen was prepared from cyclen by using three equivalents
À
Me TACD ((Me TACD)H=Me [12]aneN4:1,4,7-trimethyl-
A
T
U
G
T
E
N
N
A
H
T
N
T
R
N
U
G
3
3
3
3
[6]
1
,4,7,10-tetraazacyclododecane) along with their reactivity
À
for the conversion of furanics. Me TACD is a monoanionic
3
[5]
(
NNNN)-type ligand, introduced in 1985 by Lehn et al. as
an appropriate complexation agent for divalent copper and
[6a,7a,b,8]
later for other metals.
As a ten-electron donor,
[
a] Dipl.-Chem. E. Abinet, Dipl.-Chem. D. Martin,
Dipl.-Chem. S. Standfuss, Dipl.-Chem. H. Kulinna, Dr. T. P. Spaniol,
Prof. Dr. J. Okuda
Institut fꢁr Anorganische Chemie
RWTH Aachen University
Landoltweg 1, 52056 Aachen (Germany)
Fax : (+49)241-80-92644
E-mail: jun.okuda@ac.rwth-aachen.de
Scheme 1. Improved synthesis of (Me
3
TACD)H (LH).
15014
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Chem. Eur. J. 2011, 17, 15014 – 15026

FULL PAPER
[
11]
of chloral hydrate.
Reduction of the formyl groups to
[12]
methyl groups with [BH
A
H
U
G
R
N
N
(thf)],
followed by treatment
3
with hydrochloric acid and subsequent workup led to LH.
The monohydrochloride LH·HCl was extracted from
aqueous solution at pH 13 by using dichloromethane and re-
[5c]
crystallized to give X-ray quality crystals. The solid struc-
ture reveals a C -symmetric ring (Figure 1). The hole size
s
+
À
3 2
Figure 1. Molecular structure of [(Me TACD)H ] Cl (LH·HCl). Ther-
mal ellipsoids are drawn at the 50% probability level. Hydrogen atoms
in the ethylene bridge are omitted for clarity.
r(H) is commonly used to compare the size of the cavity
[
13]
within a macrocyclic ligand.
The radius of the available
[13a]
cavity in LH·HCl (r(H)=1.244(2) ꢃ) is smaller than in
the hydrochloride of cyclen (r(H)=1.9 ꢃ).
size in [(cyclen)H] Cl is larger than in LH·HCl, but a
closer look reveals different conformations adopted in their
solid structures (Figure 2). In cyclen, the nitrogen atoms
[13b–f]
The hole
+
À
Scheme 2. General synthetic routes: a) LH, THF, 3 h, RT; b) [NEt
[B(C X ) ] (X=H, F), THF, 1.5 h, RT; c) THF, p(H )=5 bar, 3 days,
08C or PhSiH
3
H]
AHCTUNGTRENNUNG
6
5
4
2
5
3
(1.5 equiv), RT, 1 h.
centers is similar and is best described as a square antiprism
formed by the nitrogen atoms of the ligand and the terminal
carbon atoms of both allyl ligands. Compounds 1-Pr and
1
-Sm show crystallographic symmetry with the metal atoms,
the amido nitrogen atom N1, a further nitrogen atom of the
Me TACD ligand, as well as the central carbon atoms of
3
Figure 2. Schematic conformation modes of the hydrochloric salt of
cyclen (left) and [(Me TACD)H ] Cl (LH·HCl, right).
3 2
both allyl ligands in the mirror plane (Figure 3, center). All
complexes show a shorter distance between the metal and
the amido nitrogen atom LnÀN1 (ꢀ2.3 ꢃ) than to the other
+
À
three amine nitrogen atoms (mean interatomic distance of
point away from the ring system in an exocyclic mode,
2.7 ꢃ). The Me TACD ligand is highly distorted due to the
sp amido nitrogen atom (sum of the C-N-C and C-N-Ln
3
+
À
2
whereas in [(Me TACD)H ] Cl the nitrogen atoms bind in
3
2
endocyclic fashion, forming a rectangle caused by an intra-
angles, see Table 1) and the resulting coplanar orientation of
[13e]
2
annular hydrogen bridge between H2 and N3.
The hydro-
the five atoms (C-C-N
A
H
U
G
R
N
U
G
[7a]
gen bonding found between protonated N1 and N3 reveals
an interatomic distance of 2.814(4) ꢃ, which is shorter than
in the analogous mono(hydrochloride) salt of 1,4,7-tris(tert-
atom.
The decreasing ionic radius on going from 1-La
to 1-Y results in an increasing bend of the ring ligand
and migration of the metal towards the cavity of the ligand.
[14]
butoxycarbonylmethyl)-1,4,7,10-tetraazacyclododecane.
On the one hand, the distance between the N -plane and
4
the metal center decreases even more with the ionic radii
(
Table 1) than expected from the lanthanide contraction.
Neutral bis
complexes [Ln ACHTUNGTRENNUNG( Me TACD) ACHUTGNERNNUG
3
Ce 1-Ce, Pr 1-Pr, Nd 1-Nd, Sm 1-Sm) were synthesized from
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(allyl) complexes: The solvent-free bis
A
H
U
G
E
N
N
On the other hand, the hole size measured in the complexes
(Table 1) hardly varies with the ionic radii of the lanthanides
and is on average 0.06 ꢃ larger than in the hydrochloric
salt.
3
3
5 2
3
the thermally stable tris ACHTUNGETRNN(UNG allyl) complexes [Ln ACHTNUGTRNNGE(U h -C H ) (1,4-
3 5 3
[15]
dioxane)] (Scheme 2). X-ray diffraction quality crystals of
the complexes 1-Y, 1-La, 1-Pr, and 1-Sm were grown at
À408C (Figure 3, Table 1). The geometry around the metal
Although the solid-state structures of 1-Y, 1-Pr, and 1-Sm
show disorder within the allyl group or the Me TACD frag-
3
ment, the disorder could be modeled well with split posi-
Chem. Eur. J. 2011, 17, 15014 – 15026
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15015

J. Okuda et al.
tions for the carbon atoms. The crystal structure of 1-La,
which does not show any disorder, differs from 1-Y, 1-Sm,
and 1-Pr by a paddle-wheel-like arrangement of the allyl
groups. In 1-La the trans-located allyl ligand (relative to the
amido nitrogen atom) shows slightly elongated LaÀC bonds
(
mean value of 2.87 ꢃ ranging from 2.791(4) to 2.918(4) ꢃ
in trans versus 2.83 ꢃ ranging from 2.808(4) to 2.859(4) ꢃ in
cis) and a larger C-C-C angle (qtrans =128.7(4) vs. q =
cis
1
27.6(4)8). While the allyl group cis to the amido nitrogen
atom shows a symmetrical coordination to the metal center,
the trans-located allyl group is displaced by the trans influ-
[16]
ence induced by the amido donor.
The dynamic behavior of 1-La in [D ]toluene solution was
8
1
investigated by H NMR spectroscopy in the temperature
range of À80 to +808C (Figure 4). At +808C, the spectrum
shows high symmetry. The signal assigned to the methane
protons at around d=6.40 ppm shows one emerging quintet
3
(
J
A
H
U
G
E
N
N
(H,H)=12.0 Hz) for both allyl groups located cis and
trans relative to the amido nitrogen atom. The simple high-
temperature NMR spectrum may be explained by a C -sym-
s
metric structure that results from a dynamic exchange of the
cis-/trans-allyl groups. This process may involve twisting of
the square antiprismatic coordination geometry by rotating
the allyl groups with the C2/C5 methine carbon atoms
moving below N2/N4 through a cubic transition state. An-
other process indicated by the broadening of the resonances
3
3
at 3.06 ( J
ACTHUNGTRENNUN(G H,H)=8.3 Hz, syn) and 2.82 ppm ( J ACHTUNGTRENNUNG( H,H)=
1
5.1 Hz, anti) is the onset of exchange between syn- and
Figure 3. Molecular structures of 1-La (top), 1-Sm (center), and 1-Y
bottom). Thermal ellipsoids are drawn at the 50% probability level. Hy-
drogen atoms are omitted for clarity. The disordered carbon atom posi-
anti-protons through s–p rearrangement, without reaching
coalescence. At 08C the coalescence of the signals for the
cis- and trans-located allyl ligands is observed as one broad
signal for the terminal protons ranging from d=2.75 to
(
tions in 1-Y are shown with only one split position.
3
.50 ppm. Correspondingly a broad signal at d=6.52 ppm
1
Figure 4. Variable-temperature H NMR spectra of 1-La in [D
8
]toluene from À80 to +808C. The left-hand side shows the methine protons (8) of the two
CH resonances (*) and the methyl groups (#) of the
allyl groups. The right-hand side shows the syn- (+) and anti-protons (ꢄ) as well as the CH
Me TACD ligand.
2
2
3
15016
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Chem. Eur. J. 2011, 17, 15014 – 15026

Rare-Earth Metal Complexes Supported by a Macrocyclic Ligand
FULL PAPER
3
3
Table 1. Selected interatomic distances [ꢃ] and angles [8] of [Ln
(thf) [BPh ] (2-Ce), and [La(Me TACD)(m-H) (3-La).
A
H
U
G
R
N
U
3
TACD)
A
H
U
G
R
N
U
G
3
H
5
)
2
] (Ln=La 1-La, Pr 1-Pr, Sm 1-Sm, Y 1-Y), [Ce
A
H
U
T
E
N
N
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -
C
3
H
5
)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
4
A
H
U
T
N
U
G
3
A
T
N
T
N
U
G
2 4
]
1
-La 1-Y
1-Sm
2-Ce
3-La
LnÀC1
LnÀC2
2.808(4)
2.859(4)
2.641(3)
2.684(4)*
LnÀC1
LnÀC2
2.782(5)
2.751(7)
2.743(3)
2.700(5)
CeÀC1
CeÀC2
2.822(3)
2.816(3)
La1ÀLa2
La1ÀLa3
3.9154(4)
3.8912(6)
2.610(8)*
LnÀC3
C1ÀC2
2.837(4)
1.388(6)
2.754(4)
–
–
–
CeÀC3
C1ÀC2
2.792(3)
1.376(5)
La1ÀLa4
La2ÀLa3
4.1544(4)
3.8916(5)
1.245(11)* C1ÀC2
.442(7)*
1.376(13)*
.260(6)*
131.1(5)
39.6(9)
1.341(6)
1.337(4)
1
C2ÀC3
1.373(6)
127.6(4)
–
–
–
C2ÀC3
1.376(5)
127.1(3)
La2ÀLa4
La3ÀLa4
4.1161(5)
4.1689(4)
1
C1-C2-C3
C1-C2-C1’
132.8(10)
2.744(5)
2.824(14)* 2.779(9)*
2
–
1.284(10)* 1.341(6)*
1
–
134.1(7)
2.716(3)
C1-C2-C3
1
LnÀC4
LnÀC5
2.791(4)
2.918(4)
2.740(3)
2.698(3)
LnÀC3
–
–
–
–
La4-H8-H7
–
174(2)
–
LnÀC4
.83(2)*
2.758(15)*
–
LnÀC6
C4ÀC5
2.887(4)
1.386(6)
2.697(3)
1.381(4)
–
–
–
–
–
La1···
r
A
H
U
G
R
N
N
(N
-plane) 1.7783(15)
2.085(3)
4
C3ÀC4
.344(9)*
1.291(6)*
–
C5ÀC6
1.374(6)
128.7(4)
1.375(4)
127.8(3)
–
–
–
–
–
r(H)
S(C-N1-La1/C)
1.365(3)
357.1
C4-C5-C6
C3-C4-C3’
128.6(13)* 131.0(9)*
1
41(3)*
141.8(14)*
2.291(4)
2.628(3)
2.653(3)
–
LnÀN1
LnÀN2
LnÀN3
LnÀN4
2.404(3)
2.715(3)
2.743(3)
2.703(3)
85.68(9)
3.509(4)
116.31(9)
4.602(4)
2.239(2)
2.567(2)
2.632(2)
2.578(2)
88.84(8)
3.420(3)
123.28(7)
4.527(3)
LnÀN1
LnÀN2
LnÀN3
2.312(6)
2.680(5)
2.702(5)
–
CeÀN1
CeÀN2
CeÀN3
CeÀN4
2.312(2)
2.699(2)
2.772(2)
2.710(2)
85.98(8)
3.483(3)
116.81(7)
4.607(3)
La2···
r
r(H)
S(C-N1-La2/C)
La3···
r
A
T
N
T
E
N
N
(N
-plane) 1.7659(15)
2.026(3)
1.306(3)
359.3
-plane) 1.7723(16)
2.069(3)
1.349(3)
358.6
-plane) 1.7833(15)
2.026(3)
4
–
N1-Ln-N3
N1-Ln-N3
N1ÀN3
86.1(2)
3.433(9)
119.5(3)
4.631(12)
87.30(13)
3.423(5)
N1-Ce-N3
A
H
U
G
R
N
U
G
4
N1ÀN3
N1ÀN3
N2-Ln-N4
N2-Ln-N2’
N2ÀN2’
121.58(14) N2-Ce-N4
r(H)
S(C-N1-La3/C)
N2ÀN4
4.588(6)
1.5250(19) Ce···
N2ÀN4
Ln···
r
r(H)
S(C-N1-Ln/C)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(N
4
-plane) 1.6491(15) 1.4681(12) Ln···
A
H
U
G
R
N
U
G
4
-plane) 1.579(8)
2.031(3)
A
H
U
G
R
N
U
G
4
-plane) 1.6190(13) La4···
A
H
U
G
R
N
U
G
4
[
13a]
2.041(2)
1.321(2)
357.4
2.005(3)
1.285(3)
359.3
r
2.020(2)
1.300(2)
358.9
r
2.035(3)
1.315(3)
358.6
r
[
13a]
r(H)
S(C-N1-Ln/C)
1.311(3)
359.0
r(H)
S(C-N1-Ce/C)
r(H)
S(C-N1-La4/C)
1.306(3)
358.9
[
*] These atoms are disordered and could be modeled with split positions.
shows the coalescence of the methine protons, which splits
into one signal for each allyl ligand at À208C. The free
°
À1
energy of activation DG =52.74 kJmol at the estimated
coalescence temperature of 08C was calculated using the
Eyring equation. As consequence of nonequivalent cis- and
3
trans-allyl groups, two sets of h -bonded allyl signals are
found at À808C. Over the entire temperature range, the
3
allyl ligands retain the h -binding mode on the NMR time-
scale. The Me TACD ligand displays eight diagnostic signals
3
for the four CH CH groups at 808C, which indicates the
2
2
rapid exchange process between the two macrocyclic ring
conformations [(lddd) and (dlll)] on the NMR timesca-
[
7a]
le.
Lowering the temperature to À208C results in the
broadening of all ring resonances. At À508C, the signals of
1
Figure 5. H NMR spectra of the paramagnetic complexes: from top to
the CH CH groups split into two sets of signals to become
bottom 1-Ce, 1-Nd, and 1-Pr in [D ]benzene.
2
2
6
distinct at À808C. Above À408C, the three methyl groups
of the Me TACD ligand show two singlets of intensity ratio
3
1
:2, consistent with C -symmetry of the ring caused by a dy-
syn- and anti-signals and those of the CH CH bridges are
s
2
2
namic exchange process in solution. Below À408C, three
distinct singlets are detected, in agreement with the asym-
metric structure found in the solid state (Figure 3, top).
The compounds 1-Ce, 1-Pr, 1-Nd, and 1-Sm display a net
broadening and a paramagnetically induced dispersion of all
so broad that assignment and integration are difficult. At
room temperature, C -symmetry on the NMR timescale is
s
found for 1-Ce, 1-Nd, and 1-Pr, indicated by nine resonances
1
in the H NMR spectrum.
1
the signals in the H NMR spectra. The magnitude varies in
the order 1-Sm<1-Ce<1-Nd<1-Pr with signals ranging
from À110 to 120 ppm for 1-Pr (Figure 5). In particular, the
Cationic mono
and 1-Nd with [NEt H][BAHCTUNTGRENNUNG
ACHTUNGTRENNUNG
3
6
5 4
Chem. Eur. J. 2011, 17, 15014 – 15026
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15017

J. Okuda et al.
3
plexes [Ln
Ln=La 2-La, Ce 2-Ce, Nd 2-Nd; X=F, Ln =La 2 -La)
Scheme 2). Compounds 2-La, 2-Ce, and 2-Nd are barely
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me TACD)
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
(thf) ][B
A
H
U
G
R
N
U
G
C3 2.792(3) ꢃ) as well as equal CÀC bond lengths of
1.376(5) ꢃ (for C1ÀC2 and C2ÀC3). The two thf molecules
that coordinate to the metal center show interatomic Ce1À
3
3
5
2
6
5 4
F
(
1
13
11
soluble in THF but H, C{ H}, and B NMR spectra could
be obtained. The H NMR spectrum of 2-La shows a sharp
O
thf
distances of 2.596(2) and 2.641(2) ꢃ, which are within
1
the expected range. The Me TACD ligand binds to the
3
triplet of triplets at d=6.16 ppm for the methine proton and
metal center in the same way as in the neutral compounds.
3
at d=2.94 and 2.26 ppm two distinct doublets for syn- ( J-
The calculated Ce1···N -plane distance of 1.6190(13) ꢃ and
4
3
[13a]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=9.3 Hz) and anti-protons ( J
A
H
U
G
R
N
U
G
hole size in 2-Ce (r(H)=1.315(3) ꢃ)
fit between the
four CH CH signals have a similar shape to those in the
values measured in the neutral compounds 1-La and 1-Pr.
The comparison of the neutral and cationic compounds in
the solid state does not reveal any difference caused by the
2
2
1
1
neutral compound 1-La. The B NMR spectrum of 2-La dis-
plays one signal at d=À6.5 ppm, consistent with the pres-
1
ence of a single compound. The H NMR spectra of the par-
higher Lewis acidity of the metal center in the cationic ana-
3
amagnetic analogues 2-Ce and 2-Nd differ from those of the
neutral precursors. In contrast to the proton signals of the
cation that are spread over a large range of chemical shifts,
the proton signals of the borate anions appear like in 2-La
at around d=6.0 ppm, thus pointing out that no interactions
between metal center and anion are found in THF solution.
The solid-state structure of the cation 2-Ce was investigat-
ed to understand the effects of the cationic metal center
logue 2-Ce, as found between [Ce
AHCTUNGTRENNGUN( h -C H ) ACHTUNTGRENNUNG( thf) ] ACHTUNGREUNNNG[ BPh ].
3 5 2 4 4
A
H
U
G
R
N
U
G
A
H
N
T
E
N
N
(thf) ] and [Ce-
3
5
3
3
3
[15d]
To enhance the solubility of the cation, [La ACHTUNGRETNN(UNG Me TACD)-
3
3
F
AHCTUNGTRENNGNU( h -C H ) ACHTUNGTRNNEUG( thf) ][B ACUTHGNTRENNGNU( C F ) ] (2 -La) was synthesized with the
3 5 2 6 5 4
Brønsted acid dimethylanilinium tetrakis(pentafluorophe-
F
nyl)borate. 2 -La provides the same cation as 2-La com-
À
bined with a fluorinated anion [B
A
H
U
G
R
N
U
G
6
5 4
compound more soluble in less polar solvents such as ben-
[17]
(
Figure 6). The compound crystallizes as an ion pair without
zene.
Dihydrido complexes: The bis(trimethylsilylmethyl) com-
plexes [Ln(Me TACD)(CH SiMe ) ] (Ln=Y, Ho, Lu) were
reported to react with phenylsilane to form the hydrido
A
H
U
G
R
N
U
G
ACHTUNGTRENNUNG
3
2
3 2
[
7a]
complexes [Ln
hydrogenolysis to give the corresponding dihydrido com-
plexes [Ln(Me TACD)H ] (Ln=La 3-La, n=4; Ln=Sm
-Sm; Scheme 2). The formation of the hydrido compounds
ACHTUNGTRNENUG( Me TACD)H ] . 1-La and 1-Sm underwent
3 2 3
AHCTUNGTRENNUNG
3
2 n
3
1
took three days at 508C and was monitored by H NMR
spectroscopy. The H NMR spectrum in [D ]THF shows a
1
8
single compound 3-La with a broad singlet at d=10.53 ppm,
assigned to the lanthanum hydride, five signals for the
CH CH protons, and two singlets for the terminal methyl
2
2
groups of the Me TACD ligand.
3
X-ray diffraction quality crystals of 3-La were grown from
a benzene solution at 58C. The solid-state structure of 3-La
contains one molecule of benzene in the lattice and does
not show any disorder, thereby allowing the location of all
hydride positions (Figure 7). Molecular lanthanum hydrides
[18]
are rare, 3-La representing the first example of structural-
ly characterized non-cyclopentadienyl-supported lanthanum
3
Figure 6. Molecular structure of the cationic part of [Ce
(thf) ] [B(C
probability level. Hydrogen atoms are omitted for clarity.
A
T
N
T
E
N
N
(Me
3
TACD)
A
T
N
T
N
U
G
C
3
H
5
)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
6 5 4
H ) ] (2-Ce). Thermal ellipsoids are drawn at the 50%
hydride. The solid-state structure shows a tetrameric La H8
4
core (Figure 8), which contains six m-bridging hydrides on
the edges, one face-capped m -hydride, and one m -hydride in
3
4
[17]
close interactions between the cation and anion. The unit
cell contains a cocrystallized THF molecule disordered
around a center of symmetry in the lattice. The geometry
around the metal center is best described by a three-legged
piano stool in which the carbon atom C2 of the allyl moiety
as well as the atoms O1 and O2 of the coordinating thf mol-
ecules build the three legs and the rhombic base is formed
by the four nitrogen atoms of the ligand scaffold. The allyl
ligand is located trans to the amido nitrogen atom and
the center, coordinated tetrahedrally by four lanthanum
atoms (q=104–1168). The structure of the tetrameric core
[19]
corresponds to the Ln H core found in [(TpMe )LnH ]
2 4
4
8
2
(Ln=Y, Sm, Yb, Lu) and in the cyclopentadienyl (Cp)-sup-
[20]
ported La H cluster. The lanthanum compound 3-La dif-
4
8
fers from the highly symmetric trinuclear cluster [Y-
[7a]
A
H
U
G
R
N
U
G
A
H
U
G
E
N
N
(3-Y) that contains only m-hydrides.
3
In 3-La, C -symmetry is found for the La H core with a the
3
4
8
m -bonded H7, the central m -H8, and La4 located on the
3
4
3
shows an h -binding mode. This is confirmed by similar CeÀ
(noncrystallographic) C -axis. Atoms La1, La2, and La3
3
C
contacts (Ce1ÀC1 2.822(3), Ce1ÀC2 2.816(3), and Ce1À
form a pseudo-hexagonal plane with H1, H2, and H3; each
allyl
15018
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ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 15014 – 15026

Rare-Earth Metal Complexes Supported by a Macrocyclic Ligand
FULL PAPER
CH CH and two for the methyl groups. The line broadening
2
2
precludes the observation of the hydrido signal in 3-Sm. The
previously reported yttrium hydrido compound prepared
from [Y ACTHUNGTERNNUN(G Me TACD) ACTHUGNTERNNUG(N CH SiMe ) ] was also obtained from
3 2 3 2
1
13
1
1
-Y. The H and C{ H} NMR spectra were identical to
those of the reported trinuclear dihydride [Y(Me TACD)(m-
H) ] (3-Y). These observations confirm that allyl ligands
A
H
U
G
R
N
U
G
ACHTUNGTRENNUNG
3
[7a]
2
3
are suitable precursors for the generation of hydrido com-
pounds and provide an alternative to the commonly used
CH SiMe ligand.
2
3
Reduction of furfural: Conversion of furfural with phenylsi-
lane by using catalytic amounts (2.5 mol%) of [Y-
[
7a]
Figure 7. Molecular structure of [La
(3-La). Thermal ellipsoids are drawn at the 50% probability level. Hy-
drogen atoms of the Me TACD ligand are omitted for clarity.
4
A
H
U
T
E
N
N
(Me
3
TACD)
4
A
H
U
G
E
N
N
(m-H)
6
A
H
U
G
R
N
U
G
3
-H)
A
H
U
G
R
N
U
G
4
-H)]
ACHTUNGENTRNUNG( Me TACD) ACTHUNGTENRNUN(G CH SiMe ) ] (4-Y), 1-La, or 3-Y was moni-
3 2 3 2
1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
tored by H NMR spectroscopy. Within 7 min, the 1,2-addi-
tion products furfuryl silanolates were produced (Scheme 3).
3
Only bis
ACHTUNGTRENNUN(G furfuryl)phenylsilane (A) and tris(furfuryl)phenyl-
silane (B), commonly difficult to access due to steric hin-
[21]
drance, were detected (Table 2). Monofurfuryl(phenyl)si-
lane, which was formed in the first step, is favored and dis-
appeared immediately under formation of A and B (Table 2,
1
-La, 67% A and 33% B). After three days the concentra-
tion of B increased, thus indicating a metal-mediated redis-
tribution reaction. At lower concentrations of 1-La ([1-La]:-
furfural=1:80), the reaction reached full conversion within
20 min. At low catalyst loadings (1:500) 13% conversion
was already observed after 30 min. The hydride 3-Y appears
to be the most active, because 87% of B was already de-
tected after a reaction time of 7 min (Table 2). In all cases,
the GC-MS analysis shows 2-furfuryl alcohol (C) as the only
final product. The side products disiloxanes or enoxysilanes
that are usually observed in the hydrosilylation of alde-
4 8
Figure 8. Side (left) and top view (right) of the La H core of 3-La.
lanthanum atom is nine-coordinated in square-antiprism ge-
ometry by four nitrogen atoms and four hydrogen atoms ad-
ditionally capped by the hydride ligand H8. La4 is eight-co-
ordinated in a piano-stool-like manner with also one addi-
tional hydride ligand H8. The La···La contacts between the
lanthanum atoms situated in the pseudo-hexagonal plane
are longer than those predicted for [Cp La H ] (La···La=
[21]
hydes
were not detected. The few examples of hydro-
silylation of furfural reported in the literature use nickel or
iron catalysts that require 20 h to achieve high conver-
4
4
8
[20]
[22,23]
3.866 ꢃ
vs. La1···La2=3.9154(4), La2···La3=3.8916(5),
(1–
sions.
and La1···La3=3.8912(6) ꢃ). The distances between La
A
H
U
G
R
N
U
As organolanthanides are known to be active catalysts in
[24]
3
) and La4, which is located on the C -axis, are ꢀ0.2 ꢃ
the hydrogenation of simple alkenes, the scope of the cat-
alyst system was explored in the hydrogenation of furfural
3
longer (La1···La4=4.1544(4), La2···La4=4.1161(5), and
La3···La4=4.1689(4) ꢃ) which
is also longer than those pre-
dicted by calculation for
[
4
Cp La H ]
.054 ꢃ ). All LaÀN distan-
(La···La=
4
4
[
8
20]
ces are longer than in the bis-
(allyl) compound 1-La; the
La···N -plane distances are
ACHTUNGTRENNUNG
4
0
1
1
1
.1 ꢃ longer (La1···N -plane=
4
.7783(15),
.7659(15),
.7723(16),
La2···N -plane=
4
La3···N -plane=
4
and
La4···N4-
plane=1.7833(15) ꢃ).
1
The H NMR spectrum of
3-Sm shows lower symmetry
than 3-La in [D ]THF solution
8
with seven signals for the
Scheme 3. Conversion of furfural into 2-furfuryl alcohol (C) and furfuryl 2-furoate (D).
Chem. Eur. J. 2011, 17, 15014 – 15026
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15019

J. Okuda et al.
Table 2. Hydrosilylation of furfural catalyzed by [Y
(CH SiMe ] (4-Y), [Y(Me TACD)(m-H )] (3-Y), and [La
(h -C ] (1-La).
A
T
N
T
E
N
N
3
TACD)-
TACD)-
Table 4. Hydrodeoxygenation of 2-methylfuran induced by 1-Y, 1-La,
1-Ce, 1-Nd, 1-Sm, or 3-La.
[
a]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
3
)
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
A
T
G
R
N
N
2
3
A
H
U
G
R
N
U
G
3
3
[a]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
H
5
)
2
[b]
Complex Solvent
Substrate
R
Conversion
[%]
Products [%]
alkene
Product ratio
alkane
Complex Complex:furfural Time
Conversion [%]
<7 min >98
7 min >98
A
B
1
-La
[D
[D
[D
[D
[D
[D
[D
[D
[D
6
6
6
6
6
6
8
8
8
]benzene
]benzene
]benzene
]benzene
]benzene
]benzene
]THF
Me
Me
Me
Me
Me
H
Me
Me
Me
60
57
53
38
43
61
17
68
72
52
42
37
70
98
33
51
40
72
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
26
[
b]
4
1
-Y
1:40
1:40
81
67
31
n.d.
n.d.
n.d.
18
19
33
69
n.d.
n.d.
n.d.
82
1-Ce
1-Nd
1-Sm
1-Y
1-La
3-La
1-La
<
[
b]
-La
3
days
min
>98
67
98
3
2
[
[
c]
1
-La
1:80
0 min
d]
[c]
1
3
-La
-Y
1:500
1:40
30 min
<7 min >98
13
[
b]
]THF
]THF
n.d.
n.d.
1
-Sm
[
a] PhSiH
3
6
(1.25 equiv). [b] [D ]benzene (0.6 mL), 258C, A:B ratio deter-
1
À1
mined by H NMR before workup. [c] 1-La (20 mg), toluene (1 mL), GC-
[a] Complex:substrate 1:1, c
ACHTUNGTRENUNNG( complex)=0.09 molL , solvent (0.5 mL),
MS analysis of a sample (0.1 mL) mixed with wet acetone (3 mL). [d]
p(H )=5.5 bar, time=6 days. [b] R=Me, F: cis-/trans-2-pentene, G: n-
2
1
-La (5 mg), furfural (414 mL). n.d.=not detected.
pentane; R=H, H: cis-/trans-2-butene, I: n-butane. [c] c AHCTUNTGERNNUN(G complex)=
LÀ1
0
.18 mol . n.d.=not detected.
with molecular hydrogen. Whereas the catalytic hydrosilyla-
tion of furfural led only to 2-furfuryl alcohol (C), the hydro-
genation of furfural at a metal to furfural ratio of 1:40 led to
a mixture of C and furfuryl 2-furoate (D) in low yield
drodeoxygenation, which involves the removal of oxygen
[25]
(Scheme 4). The CÀO bond activation of ether, essential
for this type of reaction, is known to be induced by metallo-
(
Scheme 3, Table 3). The formation of D does not depend
3
Table 3. Hydrogenation of furfural catalyzed by [Y ACHTUGNTRNEUN(G Me TACD)-
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH
2
SiMe
3
)
2
] (4-Y) and [Ln
A
H
U
G
R
N
N
(Me
3
TACD)
A
H
N
T
E
N
N
(h -C
3
H
5
)
2
] (Ln=La, 1-La; Ce,
[
a]
1
-Ce) at different overall concentrations.
Complex [furfural] Time
c
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
Conversion
[%]
Product ratio
À1
A[ molL
C
H
T
U
N
G
T
R
E
N
N
U
N
G
]
A
H
U
G
R
N
N
C
D
Scheme 4. Hydrodeoxygenation of furan and 2-methylfuran induced by
1
1
4
4
-La
1.0
1.0
1.0
0.5
6
6
6
6
29
14
17
11
64
86
89
89
36
14
11
11
1
-Y, 1-La, 1-Ce, 1-Nd, and 1-Sm.
-Ce
[
[
b]
-Y
-Y
b]
cene hydrides and half-sandwich alkyls of rare-earth
[
a] Complex:furfural 1:40, [D
8
]THF (0.6 mL), p(H
2
)=5 bar, 508C.
[26]
1
metals. Teuben et al. reported [Cp* YH ]-mediated hydro-
2 2
[
b] About 6% of unidentified byproduct detected by H NMR spectros-
deoxygenation of furan leading to the formation of n-butane
copy and GC-MS (m/z 188).
[26a]
and dimeric oxo-yttriocene [(Cp* Y)2 ACHUTNGRENNUG( m-O)].
2
The activity and selectivity in the hydrodeoxygenation of
2-methylfuran was investigated in [D ]benzene and [D ]THF
as well as with different metal complexes 1-Y, 1-La, 1-Ce,
1-Nd , and 1-Sm (Scheme 4, Table 4). The highest activity in
[
7a]
on the concentration of the in situ formed 3-Y, but the
total yield increases at higher concentration. The highest
conversion was found for 1-La but 4-Y showed the highest
selectivity towards the furfuryl alcohol C. The experiments
show that the catalytic hydrogenation of furfural is possible,
but no full conversion was attained under the conditions in-
6
8
[D ]benzene is observed with 1-La and can further be in-
6
creased by using [D ]THF. In contrast, the selectivity to-
8
wards the formation of cis/trans-2-pentene (F) decreases
with the metal size. This indicates that with larger metals
further hydrogenation to n-pentane (G) occurs, which is
vestigated.
1
In H NMR experiments in [D ]THF, furfural was treated
8
[27]
with 3-Y in varying ratios (3-Y:furfural=1:2, 1:4, 1:8, 1:12)
without additional hydrogen. After eight days at 258C at
ratios of 1:2, 1:4, and 1:8, signals attributed to C and D were
found in the reaction with 3-La.
Kinetic investigations
show that the substitution pattern of furan also has an influ-
ence on the activity, indicating an a activation of the furan
1
[28]
found by GC-MS analysis, whereas in H NMR spectra D
ring mediated by the metal center (Figure 9). This activa-
and broad signals attributed to an yttrium furfuryl alkoxide
tion was further investigated by deuteration experiments.
species as well as other byproducts are found. At a ratio of
Treatment of furan derivatives with D and using stoichio-
2
1
1
:12, H NMR spectra also show the presence of C besides
metric amounts of metal complex was performed to reveal
the regioselectivity during the hydrodeoxygenation. In the
conversion of furan in the presence of 1-Y, after 22 h all
D and the yttrium furfuryl alkoxide species.
1
peaks assigned to furan protons disappeared in the H NMR
Hydrogenation of furan and 2-methylfuran: The conversions
spectrum. The GC-MS chromatogram of the solution
of furan and 2-methylfuran in the presence of hydrogen and
showed two signals, attributed to [D –D ]2-butene (m/z 64)
7
8
1-Y, 1-La, 1-Ce, 1-Nd, or 1-Sm lead to the corresponding al-
and [D –D ]furan. The presence of [D –D ]furan indicates a
3 4 3 4
kenes and alkanes (Table 4). This reaction is formally a hy-
metal-mediated H/D scrambling of the protons in the a and
15020
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ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 15014 – 15026

Rare-Earth Metal Complexes Supported by a Macrocyclic Ligand
FULL PAPER
sors for thermally stable allyl complexes supported by a
3
Me TACD ligand [Ln
A
H
U
G
R
N
U
G
A
T
N
T
E
N
N
(h -C H ) ] (Ln=Y 1-Y,
3
3
3
5 2
La 1-La, Nd 1-Nd, Ce 1-Ce, Pr 1-Pr, Sm 1-Sm). These bis-
3
AHCTUNGTRENNUNG( allyl) compounds display two h -bonded allyl fragments in
the solid state as well as in solution. Protonolysis by Brønst-
ed acids generates allyl cations as solvent-separated ion
3
pairs [Ln
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
A
H
N
T
E
N
G
A
H
U
G
R
N
U
G
3
3
5
2
6
5 4
F
Ln=La 2-La, Ce 2-Ce, Nd 2-Nd; X=F, La 2 -La). Allyl
complexes of the lighter lanthanides are suitable precursors
for the synthesis of hydrido compounds [Ln ACHTUNGNRTEUNG( Me TACD)H ]
3 2 n
[7a]
(
Ln=Y 3-Y, n=3;
thus providing an alternative to the commonly used
CH SiMe complexes. [La (Me TACD) (m-H) (m -H)(m -H)]
Ln=La 3-La, n=4; Ln=Sm 3-Sm),
A
H
U
G
R
N
U
A
H
U
G
R
N
N
A
H
U
G
R
N
N
ACHTUNGTRENNUNG
2
3
4
3
4
6
3
4
(
3-La) is the first example of a structurally characterized
Figure 9. Conversion of furan and 2-methylfuran with 1-La in
non-cyclopentadienyl-supported lanthanum hydride. A tet-
rameric La H core is found in the solid-state structure with
one m -hydride ligand in the center. The nuclearity of the hy-
[
6
D ]benzene.
4
8
4
b positions. In the conversion of 2-methylfuran with 1-Y,
beyond [D –D ]2-pentene also a- and b-H/D exchange
drido cluster with a Me TACD ligand thus depends on the
3
metal size.
The complexes [Ln
0
10
1
3
leading mainly to [D ]2-methylfuran is found by H NMR
A
H
U
G
R
N
U
G
2
3
2
3
5
spectroscopy and GC-MS analysis. With larger metals 1-La
and 1-Sm, conversion to [D –D ]2-pentene and deuteration
1-La, Y 1-Y; R=H, Ln=Y 3-Y; R=CH SiMe , Ln=Y
2 3
4-Y ) catalyzed the hydrosilylation of furfural and hydroge-
nation to the corresponding alcohol or furfuryl 2-furoate.
The active species in these reactions is presumably the dihy-
0
10
of the a proton in 2-methylfuran were observed. In an ex-
periment with 1-La performed over 60 h, the signal assigned
to the a proton disappeared and the complete transition of
the b-H signal from a multiplet to a doublet indicates an H/
D exchange mainly in the a position (Figure 10). These re-
sults were confirmed by GC-MS analysis, in which lower
dride complex [Ln ACHTUNGTRENN(GU Me TACD)H ] (Ln=Y 3-Y, La 3-La)
3 2 n
formed by hydrogenation of the neutral bis ACHUTGTNRNENUGN( allyl) moiety.
Hydrodeoxygenation of furan and 2-methylfuran leading to
the formation of olefins and alkanes was observed by using
3
amounts of [D ]2-methylfuran were detected compared to
[Ln
A
H
U
G
R
N
N
(Me TACD)(R) ] (R=h -C H , Ln=Y 1-Y, La 1-La, Ce
2
3
2
3
5
the reaction with 1-Y.
1-Ce , Pr 1-Pr, Nd 1-Nd, Sm 1-Sm; R=H, Ln=La 3-La).
For the hydrodeoxygenation of 2-methylfuran at ambient
D
pressure with [La
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me TACD)D ] (3 -La) without addition
3
2
of D , two signals corresponding to [D –D ]2-pentene and
2
1
5
Experimental Section
[
D ]2-methylfuran were found by GC-MS. Thus, the scram-
0
bling induced by the H/D exchange only takes place in the
presence of excess D2.
General considerations: All operations were performed under an inert
atmosphere of argon by using standard Schlenk-line or glovebox tech-
niques. THF, toluene, 1,4-dioxane, furan, 2-methylfuran, 2,5-dimethylfur-
an, deuterated THF, and benzene were dried over sodium benzophenone
ketyl. n-Pentane was dried over sodium benzophenone ketyl/triglyme.
3
PhSiH was dried over sodium. The following compounds were prepared
[
11]
according to published procedures: 1,4,7-triformylcyclen,
[Y-
[
7a]
3
A
H
U
G
R
N
N
3
TACD)
A
T
N
T
E
N
G
2
SiMe
3
)
2
] (4-Y),
[Ln
A
H
N
R
N
G
3 5 3
H ) (1,4-dioxane)] (Ln=Y,
[
15]
3
[15d]
[Nd
A
H
U
G
R
N
U
(h -C
3
H
5
)
2
A
H
U
G
E
N
N
3
][B
A
T
G
R
N
U
G
6
H
5
)
4
].
All other
chemicals were commercially available and used after appropriate purifi-
cation. NMR spectra were recorded on a Varian Mercury 200BB spec-
1
13
1
trometer, on a Bruker DRX 400 spectrometer ( H 400.1 MHz, C{ H}
1
1
00.6 MHz) or on a Varian Unity 500 spectrometer ( H 499.6 MHz,
C{ H} 125.6 MHz). All chemical shifts are given in ppm and were refer-
1
3
1
enced internally by using the residual solvent resonances and reported
relative to SiMe . For GC-MS analysis, the filtered reaction solution was
analyzed by a Shimadzu GCMS-QP2010 Plus instrument run on helium
as carrier gas.
4
Figure 10. Deuteration of 2-methylfuran in the presence of 1-La per-
1
formed in [D
6
]benzene at 508C analyzed by H NMR spectroscopy at the
start of the reaction, and after 18, 46, and 60 h.
Single-crystal X-ray diffraction measurements were performed on a
Bruker AXS diffractometer equipped with an Incoatec microsource and
an APEX area detector using MoKa radiation. Experimental parameters
and refinement results are given in Table 5. The data reductions were
Conclusion
[
29a]
performed with the Bruker SAINT software.
Absorption corrections
were carried out by using the program SADABS or Mulabs as imple-
The synthesis of the pro
proved as a two-step reaction starting from the commercial-
ly available cyclen. Tris(allyl) complexes are suitable precur-
A
H
U
G
R
N
U
G
A
H
U
G
R
N
N
gand (Me TACD)H (LH) was im-
[29b,c]
3
mented in the program system Platon.
direct methods using the program SIR-92,
The structures were solved by
[29d]
except for the structure of
A
H
U
G
R
N
U
G
1-Pr that was solved by isotypic replacement using the coordinates of
Chem. Eur. J. 2011, 17, 15014 – 15026
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15021

J. Okuda et al.
Table 5. Crystallographic data for complexes LH·HCI, 1-La, 1-Pr, 1-Sm, 1-Y, 2-Ce, and 3-La.
Compound
LH·HCl
1-La
1-Pr
1-Sm
1-Y
2-Ce
3-La
empirical
C
23
H
56
C
l4
N
8
C
17
H
35LaN
4
C
17
H
35
N
4
Pr
C
17
H
35
N
4
Sm
C
17
H
35
N
4
Y
C
96
H
140
B
2
Ce
2
N
8
O
5
50 4 16
C H114La N
formula
À1
M
r
[gmol
]
586.56
434.40
436.40
445.84
384.40
1788.02
1495.20
crystal size [mm]
crystal color
and habit
crystal system
space group
a [ꢃ]
b [ꢃ]
c [ꢃ]
a [8]
b [8]
0.20ꢄ0.08ꢄ0.08 0.14ꢄ0.08ꢄ0.05 0.12ꢄ0.08ꢄ0.05 0.22ꢄ0.06ꢄ0.06 0.34ꢄ0.28ꢄ0.17 0.23ꢄ0.20ꢄ0.18
0.45ꢄ0.41ꢄ0.30
yellow
block
orthorhombic
1 1 1
P2 2 2
12.9291(15)
22.025(3)
22.570(3)
90.00
90.00
90.00
colorless
rod
colorless
block
grey
block
orange
block
yellow
rod
colorless
block
orthorhombic
Pbcn
orthorhombic
Pccn
tetragonal
tetragonal
monoclinic
triclinic
P1
¯
P4
2
/mbc
P4
2
/mbc
P2
1
/n
15.147(3)
19.473(4)
10.882(2)
90.00
90.00
90.00
19.173(3)
13.896(2)
14.715(2)
90.00
90.00
90.00
18.8913(18)
18.8913(18)
11.1454(11)
90.00
90.00
90.00
18.7546(3)
18.7546(3)
11.1890(4)
90.00
90.00
90.00
8.7065(15)
13.856(2)
15.723(3)
90.00
94.028(3)
90.00
9.1271(5)
14.6650(7)
17.1018(9)
76.9905(8)
84.5358(8)
86.7703(8)
2218.7(2)
1
g [8]
V [ꢃ ]
3
3209.7(11)
4
3920.5(10)
8
3977.6(7)
8
3935.56(17)
8
1892.1(6)
4
6427.1(14)
4
1.545
Z
À3
1
calcd [g cm
]
1.214
1.472
1.457
1.505
1.349
1.338
T [K]
(MoKa) [mm
(000)
100(2)
0.395
1272
130(2)
2.183
1776
130(2)
2.453
1792
130(2)
2.987
1816
100(2)
3.086
816
130(2)
1.069
938
100(2)
2.649
3015
À1
m
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
]
F
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
q range [8]
hkl indices
2.53–21.44
Æ15,
1.81–30.66
Æ27,
2.41–30.60
À25–14,
Æ26,
2.42–28.12
Æ24,
2.60–29.83
Æ12,
1.23–30.78
À13–12,
Æ20,
1.82–30.10
Æ17,
Æ19,
Æ19,
Æ24,
Æ19,
À29–30,
Æ31
Æ11
Æ20
À14–15
28176
Æ14
À22–21
27370
Æ23
number of
22501
52604
50632
32916
91538
refl. collected
number of
1425
4100
2057
2025
3499
9773
16789
refl. observed
ACHTUNGTRENNUNG( I> 2s(I))
number of
1821
A
H
U
G
R
N
U
G
5803
A
H
U
G
R
N
U
G
3105
A
H
U
G
R
N
U
G
2520
A
H
U
G
R
N
N
(0.0806)
5376
A
H
U
G
R
N
U
G
12570
A
H
N
T
E
N
G
17520 ACHTUNGTRENNUNG( 0.0604)
ind. refl. (Rint
)
data/rest./par.
1821/0/174
0.0398,
5803/0/242
0.0339,
0.0690
0.0638,
0.0871
3105/0/105
0.0471,
0.0904
0.0867,
0.1029
2520/0/108
0.0256,
0.0569
0.0350,
0.0587
5376/0/241
0.0393,
0.0817
0.0788,
0.0952
12570/0/507
0.0355,
0.0760
0.0491,
0.0955
17520/0/675
0.0263,
0.0569
0.0283,
0.0577
R
1
, wR
2
(I> 2s(I))
0
.0937
0.0527,
.988
R
1
, wR
2
(all data)
0
goodness-of-fit
on F
1.026
1.100
0.950
0.963
1.007
0.970
1.036
2
largest diff. in
peak and hole [e ꢃ
0.217,
À0.302
2.225,
À1.499
1.027,
À1.518
0.925,
À0.575
0.555,
À0.493
1.660,
À1.070
1.004,
À0.858
À3
]
1
1
-Sm. All refinements were carried out by the full-matrix least-squares
orless oil (480 mg, 2.237 mmol, 71%). H NMR ([D
1
]chloroform, 258C):
), 2.27 (m, 8H; CH ), 2.30–2.37
), 2.48–2.57 ppm (m, 4H; CH ), signal for NH not detected;
C{ H} NMR ([D ]chloroform, 258C): d=43.5 (CH ), 44.5 (CH ), 45.6
); elemental analysis calcd
method using SHELXL-97 as implemented in the WinGX program sys-
tem.
for several carbon atoms within one allyl ligand and the Me
The disorder was modeled by using split positions for the carbon atoms.
Compound 2-Ce crystallized with an additional solvent molecule of THF
in the lattice. The hydrogen atoms were included in idealized positions,
except for the position of H1 in LH·HCl, the hydrogen atoms within the
allyl ligands in 1-La, as well as the hydride atoms in 3-La (H1–H8) that
were refined in their positions. The graphical representations in the Fig-
d=2.14 (s, 3H; CH
(m, 4H; CH
3
), 2.16 (s, 6H; CH
3
2
[
29e,f]
The structures of 1-Pr, 1-Sm, and 1-Y show disordered positions
TACD ring.
2
2
1
3
1
3
1
3
3
(CH
(%) for C11
2
), 53.4 (CH
2
), 55.0 (CH
2
), 55.1 ppm (CH
2
À1
H
26
N
4
(M=214.35 gmol ): C 61.64, H 12.23, N 26.14; found:
C 61.15, H 12.39, N 25.75; X-ray diffraction quality crystals of the hydro-
chloride LH·HCl were obtained from the hydrochloric acid solution of
the crude mixture and subsequent neutralization with NaOH to pH 13,
followed by extraction with dichloromethane and crystallization from a
[
29g]
ures were performed with the program DIAMOND.
CCDC-833281
saturated dichloromethane solution.
(
(
(
LH·HCl), CCDC-833282 (1-La), CCDC-833283 (1-Pr), CCDC-833284
1-Sm), CCDC-833285 (1-Y), CCDC-83328 (2-Ce), and CCDC-833287
3-La) contain the supplementary crystallographic data for this paper.
3
[
1
C
La
A
H
U
G
E
N
N
(Me
3
TACD)
A
H
U
G
R
N
U
(h -C
3
H
5
)
2
]
(1-La):
A
solution of LH (214 mg,
3
.00 mmol) in THF (5 mL) was added dropwise to a solution of [La
H ) (1,4-dioxane)] (350 mg, 1.00 mmol) in THF (5 mL). The resulting
mixture was stirred for 2 h, filtered, and dried under reduced pressure.
The resulting solid was washed with n-pentane (4ꢄ3 mL) and dried to
give 1-La as a colorless powder (387 mg, 90%). H NMR ([D
258C): d=1.69 (br m, 4H; CH
2.14 (dd,
2.28 (br s, 2H; CH
4.8 Hz, 2H; CH ), 3.03 (d, J
(H,H)=8.7 Hz, 4H; syn-CH
(H,H)=5.5 Hz, 2H; CH ), 3.56 (td,
(H,H)=5.5 Hz, 2H; CH ), 6.60 ppm (tt, J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -
3 5 3
These data can be obtained free of charge from The Cambridge Crystal-
lographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[Me
3
TACD]H (LH): 1,4,7-Triformylcyclen (806 mg, 3.145 mmol) was
(thf)] in THF (50 mL, 1.0m) and stirred
6
]benzene,
treated with a solution of [BH
3
A
H
U
G
R
N
U
2
), 1.74 (s, 3H; CH
3
), 1.99 (br s, 2H; CH
), 2.26 (s, 6H; CH
2
),
),
2
3
for 72 h with heating at reflux. Water (10 mL) was added at 08C and,
after removal of the volatiles at reduced pressure, the afforded colorless
powder was treated with hydrochloric acid (50 mL, 2.0m) and heated at
reflux for 2 h. The volatiles were removed to give colorless microcrystals,
which were dissolved in water. The solution was filtered through an
J
A
H
U
G
R
N
U
J
A
H
U
G
R
N
U
G
2
3
2
3
3
2
J
A
H
U
G
E
N
N
A
H
U
G
R
N
U
G
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=
3
2
A
H
U
G
R
N
U
G
2
2
), 3.26
3
2
3
(d,
J
A
H
U
G
R
N
U
G
2 2
CHCH ), 3.29 (dd, JACTHNUTRGENNUG
2
3
3
A
T
N
R
N
G
2
J AHCTUNGTREUNNNG( H,H)= J ACTHUNGTRENNUN(G H,H)=12.3 Hz, J-
À
3
3
anion-exchange resin (DOWEX-1ꢄ8–200, OH ) affording a viscous col-
A
T
N
R
N
U
2
A
H
U
G
R
N
U
G
A
H
U
G
E
N
N
(H,H)=8.7 Hz,
15022
www.chemeurj.org
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 15014 – 15026

Rare-Earth Metal Complexes Supported by a Macrocyclic Ligand
FULL PAPER
1
2
2
CH
CH
H; CH
2
CHCH
2
); H NMR ([D
8
]THF, 258C): d=2.36 (s, 3H; CH
ACTHUNGTNERNUNG( H,H)=11.8, J ACHTNUGTRENNUNG
3
),
(H,H)=4.5 Hz, 2H;
), 2.59–2.67 (br s, 2H; CH ), 2.63 (s, 6H;
), 2.81–2.92 (br s, 2H; CH
of LH (355 mg, 1.66 mmol) in THF (3 mL). After stirring for 2 h, the sol-
vent was removed under reduced pressure and the remaining product
was dissolved in a toluene/n-pentane mixture. Cooling at À308C gave
2
3
.37–2.47 (br s, 4H; CH
2
), 2.50 (dd, J
CHCH
CHCH
2
), 2.54 (bd, 4H; CH
), 2.79 (bd, 4H; CH
2
2
2
2
1
3
2
2
2
), 2.88 (td, J-
1-Sm (700 mg, 95%) as orange crystals. H NMR ([D ]benzene, 258C):
6
3
3
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)= J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=12.4 Hz,
J
A
H
U
G
R
N
U
G
2
), 3.13 (dd, J-
(H,H)= J
d=À0.70 (br s; CH ), À0.06 (br s; CH ), 0.41 (br s; CH ), 0.57 (br s;
3
2
2
3
2
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=12.3,
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=5.6 Hz, 2H; CH
(H,H)=5.6 Hz, 2H; CH ), 6.13 ppm (m, 2H; CH
H NMR ([D ]toluene, 808C): d=1.75–1.88 (m, 4H; CH
CH ), 2.11–2.18 (m, 2H; CH
H; CH ), 2.33 (s, 6H; CH
2
), 3.64 (td,
J
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
3 2 2 2
CH ), 2.74 (br s; CH ), 2.88 (br s; CH ), 3.65 (br s; CH ), 4.34 (br s;
3
1
2.1 Hz,
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
2
CHCH
2
2 2 2 2 2
CH ), 5.55 (br s; CH CHCH ), 7.57 (br s; CH CHCH ) 11.82 ppm (br s;
1
13
1
8
2
), 1.87 (s, 3H;
2 2 6 2
CH CHCH ); C{ H} NMR ([D ]benzene, 258C): d=40.9 (CH ), 41.9
2
3
3
2
), 2.18 (dd, J
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
2 3 3 2 2 2
(CH ), 44.6 (CH ), 51.2 (CH ), 54.8 (CH ), 57.4 (CH ), 66.7 (CH ), 67.8
2
2
2
3
3
), 2.31–2.40 (m, 2H; CH
(H,H)=4.8 Hz, 2H; CH
2
), 2.71 (td, J-
2 2
(CH ), 149.8 (CH), 161.1 ppm (CH ); elemental analysis calcd (%) for
3
3
À1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)= J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=12.3 Hz,
(H,H)=15.1 Hz, 4H; anti-CH
J
A
H
U
G
R
N
U
G
2
), 2.82 (bd, J-
17 35 4
C H N Sm (M=445.85 gmol ): C 45.80, H 7.91, N 12.57, Sm 33.72;
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
CHCH
2
), 3.06 (bd,
J
A
H
U
G
R
N
U
(H,H)=8.3 Hz, 4H;
found: C 43.74, H 7.41, N 12.93, Sm 32.8.
2
3
syn-CH
3
6
2
CHCH
2
), 3.17 (dd,
J
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
N
2
),
),
3
3
[
Y
A
H
U
G
R
N
U
G
3
TACD)
A
H
U
G
R
N
N
(h -C
3
H
5
)
2
] (1-Y): A solution of [Y
A
H
N
T
E
N
N
3
H
5
)
3
(1,4-diox-
2
3
3
.56 (td,
.40 ppm (“quint”,
]toluene, À808C): d=0.72 (d,
(H,H)=14.6 Hz, 1H; CH ), 1.15 (d, J
(H,H)=6.3 Hz, 1H; CH
), 1.98–2.17 (m, 3H; CH ), 2.20 (s, 3H; CH
), 2.48 (m, 2H; CH ), 2.74 (m, 1H; CH ), 2.83 (m, 1H; CH
.98–3.06 (m, 4H; CH CHCH ), 3.18–3.56 (m, 2H; CH
CHCH
(H,H)=8.5 Hz, 1H; CH
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)= J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=12.0 Hz,
JACHTUNGTRENNUNG
2
ane)] (300 mg, 1.00 mmol) in THF (10 mL) was treated with a solution of
LH (214 mg, 1.00 mmol) in THF (3 mL). After stirring for 2 h, the sol-
vent was removed under reduced pressure and the remaining solid was
3
1
J
A( H,H)=12.0 Hz, 2H; CH
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
CHCH
2
); H NMR
), 0.89 (d,
(H,H)=12.8 Hz, 1H; CH ), 1.57
(H,H)=
), 2.26 (s,
),
3
(
J
[D
8
J
A
H
U
G
R
N
U
2
3
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
A
H
U
G
R
N
U
2
dissolved in a toluene/n-pentane mixture. Cooling at À308C gave 1-Y
3
3
(
s, 3H; CH
3
), 1.72 (bd,
3.6 Hz, 1H; CH
H; CH
J
A
H
U
G
R
N
U
G
2
), 1.78 (d,
J
A
H
U
G
R
N
U
G
1
(
(
280 mg, 73%) as yellow crystals. H NMR ([D
6
]benzene, 258C): d=1.76
1
3
2
2
2
3
2
3
s, 3H; CH
3
), 1.80–1.47 (br m, 4H; CH
2
), 2.09 (dd,
), 2.31–2.21 (br s, 4H; CH
(H,H)=6.3 Hz, 2H; CH ), 2.69–
JACHTUNGTRENNUNG
3
2
2
2
A
H
U
G
R
N
U
G
), 2.23 (s, 6H; CH
2
3
2
3
), 3.37 (d, J-
(H,H)=15.3 Hz, 2H;
2
3
3
2
2
2
2
2
6
.79 (td,
J
A
H
U
G
E
N
N
(H,H)= J
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
N
2
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=15.3 Hz, 2H; CH
2
2
), 3.47 (d,
J
A
H
U
T
E
N
N
2
3
.96 (br s, 4H; anti-CH
.5 Hz, 2H; CH
2
2
J
A
H
U
G
R
N
N
J ACHTUNGTRENNUNG( H,H)=
3
3
CH
2
CHCH
2
), 3.61 (d,
), 6.35 (tt,
), 6.88 ppm (tt,
J
A
H
U
G
R
N
U
G
2
), 3.66 (d,
J
A
H
U
T
E
N
N
2
2
2
2
3
3
8
.3 Hz, 1H; CH
2
J
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
N
3
3
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
N
2
3
3
CH
CH
2
2
CHCH
CHCH
2
2
J
A
H
U
G
E
N
N
J
A
H
U
G
R
N
U
G
13
1
2
5
H; CH
2
CHCH
2
6
3
1
3
1
); C{ H} NMR ([D
), 56.0 (CH
6
3
0.2 (CH
3
2
2
2
2
(
CH
3
), 52.5 (CH
CHCH ), 148.0 ppm (CH
), 49.0 (CH
), 70.5 (CH CHCH ), 148.1 ppm (CH
calcd (%) for C17
2
2
), 56.2 (CH
2
), 62.1 (CH
); C{ H} NMR ([D
), 56.7 (CH
CHCH
2
(
CH
2
2
2
2
2
À1
2
1
3
1
(
CH
2
2
2
CHCH
2
8
35 4
H N
d=46.3 (CH
CH
3
3
), 53.5 (CH
2
2
2
1
(
2
2
2
2
À1
2
3
3 3 5 2 6 5 4
[La AHCTUNGTRENNUN(G Me TACD) ACHTUNGRTENNNU(G h -C H ) ACHTUNGTENRNUN(G thf) ][B AHCTUNGTRENGNUN( C H ) ] (2-La): A solution of 1-La
H
35LaN
4
(
87 mg, 0.20 mmol) in THF (2.5 mL) was treated with a solution of
found: C 46.94, H 8.04, N 12.85.
[
NEt H][B(C ] (84 mg, 0.20 mmol) in THF (2.5 mL). After stirring
3
A
H
U
G
E
N
N
6 5 4
H )
3
[
Ce
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C
3
H
5
)
2
]
(1-Ce):
A
solution of LH (214 mg,
for 1.5 h, the solvent was removed under reduced pressure and the re-
3
1
C
.00 mmol) in THF (5 mL) was added dropwise to a solution of [CeACHTUNGTRENNUNG
maining product was washed with n-pentane (4ꢄ2.5 mL) to afford 2-La
3
H
5
)
3
1
(
2
149 mg, 0.158 mmol, 79%) as a colorless powder. H NMR ([D
58C): d=1.78 (m, 8H; b-thf), 2.26 (d, JAHCTUNTGENRNUG
8
]THF,
solution was stirred for 2 h, filtered, and dried under reduced pressure.
The resulting solid was washed with n-pentane (4ꢄ3 mL) and dried to
give an orange powder (328.5 mg, 75%). H NMR ([D
3
CH
3
2
2
CHCH
H; CH ), 2.53 (s, 6H; CH
H; CH
2
), 2.06 (br s, 2H; CH
2
2
1
6
]benzene, 258C):
2
3
3
3
), 2.56 (dd,
J
A
T
N
T
E
N
N
(H,H)=12.5,
J
A
T
N
T
E
N
N
d=À17.90 (br s), À14.44 (s), À8.38 (br s), À5.80 (br s), À2.08 (br s), 3.27
2
3
3
2
), 2.86 (td,
J
A
H
U
G
R
N
U
(H,H)= J
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
U
G
1
3
1
(
(
5
m), 12.64 (br s), 28.50 (br s), 29.95 ppm (br s); C{ H} NMR
[D ]benzene, 258C): d=11.3 (CH ), 23.7 (CH ), 34.7 (CH ), 35.4 (CH ),
6.2 (CH
analysis calcd (%) for C17
3
2
CH
2
), 2.94 (d,
J
A
H
U
T
E
N
N
2
2
), 3.13 (dd, J-
6
3
3
2
2
3
2
3
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
U
G
2
J
A
H
U
G
R
N
U
G
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=
2
), 84.4 ppm (CH
2
), allyl signal could not be detected; elemental
3
3
1
2.5 Hz,
J
A
H
U
G
R
N
U
G
2
), 3.62 (m, 8H; a-thf), 6.16 (tt, J-
À1
H
35
N
4
Ce (M=435.61 gmol ): C 46.87, H 8.10,
3
3
A
H
U
G
R
N
N
J
A
H
U
G
R
N
U
G
2
CHCH
(H,H)=7.5 Hz, 8H; m-Ph), 7.28 ppm (m,
8H; o-Ph); C{ H} NMR ([D ]THF, 258C): d=26.4 (b-thf), 46.9 (CH ),
2
), 6.72 (t,
J ACHTUNGTRENNUNG( H,H)=
N 12.86; found: C 47.09, H 7.83, N 12.72.
3
7
JACHTUNGTRENNUNG
3
13
1
[
Pr
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C
3
H
5
)
2
] (1-Pr): A solution of LH (64 mg, 0.30 mmol)
8
3
3
in THF (5 mL) was added dropwise to a solution of [Pr
A
H
U
G
R
N
N
(h -C
3
H
5
)
3
(1,4-di-
3 2 2 2 2
48.5 (CH ), 53.7 (CH ), 55.6 (CH ), 56.9 (CH ), 61.4 (CH ), 68.2 (a-thf),
oxane)] (106 mg, 0.30 mmol) in THF (5 mL). The resulting solution was
stirred for 2 h, filtered, and dried under reduced pressure. The resulting
solid was washed with n-pentane (4ꢄ3 mL) and dried to give a pale
75.1 (CH CHCH ), 121.9 (p-Ph), 125.7 (m-Ph), 137.2 (o-Ph), 149.2
2
2
1
11
1
(
(
C
CH
[D
2
CHCH
2
), 165.2 ppm (quart, J ACHTUNGRTENUNN(G B,C)=49.3 Hz; i-Ph); B{ H} NMR
8
]THF, 258C): d=À4.70 ppm; elemental analysis calcd (%) for
1
À1
green powder (52 mg, 40%). H NMR ([D
6
]benzene, 258C): d=À97.2,
46
H
66
N
4
BLaN
4
O
2
(M=856.43 gmol ): C 64.49, H 7.76, N 6.54; found:
13 1
À87.2, À54.6, À45.5, À33.5, 12.1, 65.9, 103.9, 115.4 ppm; C{ H} NMR
C 58.89, H 6.24, N 7.32.
(
[D
6
]benzene, 258C): d=À70.4, À53.4, À30.2, À27.0, 74.8, 112.6,
92.5 ppm; elemental analysis calcd (%) for Pr (M=
3
F
[
La
A
H
U
T
E
N
N
(Me
3
TACD)
A
H
U
G
E
N
N
3
H
5
)
A
H
U
G
R
N
N
2
][B
A
T
N
T
E
U
(C
6
F
5
)
4
]
(2 -La):
A
solution of
1
4
1
17 35 4
C H N
[
HNMe
2
Ph][B(C
A
H
U
G
R
N
U
G
6
F
5
)
4
À1
35.61 gmol ): C 46.79, H 8.10, N 12.84; found: C 44.12, H 7.05, N
dropwise to a solution of 1-La (87 mg, 0.20 mmol) in THF (2.5 mL) and
the mixture was stirred for 1.5 h. All volatiles were removed under re-
duced pressure. The resulting light brown powder was washed with n-
2.97.
3
[
1
Nd
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C
3
H
5
)
2
]
(1-Nd):
A
solution of LH (214 mg,
3
.00 mmol) in THF (2 mL) was added dropwise to a solution of [Nd
A( h -
H
U
G
R
N
U
G
F
pentane (4ꢄ3 mL) and dried under reduced pressure to afford 2 -La
C
3
H
5
)
3
(1,4-dioxane)] (356 mg, 1.00 mmol) in THF (2 mL). The resulting
1
(
221 mg, 90%). H NMR ([D
8
]THF, 258C):d=1.77 (m, 8H; b-thf), 2.30
CHCH ), 2.47 (s, 3H; CH ), 2.54 (dd,
(H,H)=5.0 Hz, 2H; CH ), 2.43–2.72 (br m, 6H; CH ),
(H,H)=
CHCH ), 3.01
(H,H)=5.4 Hz, 2H; CH
solution was stirred for 2 h, filtered, and dried under reduced pressure.
3
(
J
d, J
A
H
U
G
R
N
U
G
2
2
3
The resulting solid was washed with n-pentane and dried to give a green
2
3
A
H
N
T
N
U
G
J
A
H
U
G
R
N
U
G
2
2
1
powder (286 mg, 57%). H NMR ([D
8
]THF, 258C): d=À56.78 (br s),
2
3
3
2
4
3
), 2.90 (td,
J
A
H
U
G
R
N
U
G
A
T
N
T
E
N
N
(H,H)=12.8 Hz,
JACHTUNGTRENNUNG
À49.78 (br s), À27.37 (br s), À16.86 (br s), À13.48 (br s), 6.47 (br s),
3
2
J
A
H
U
G
R
N
N
2
2
1
3
1
2
0.72 (br s), 63.59 (br s), 74.57 ppm (br s); C{ H} NMR ([D
8
]THF,
2
3
(
(
m, 2H; CH
td,
2
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
2
), 3.31
2
58C): d=À41.6, À10.5, À0.8, 0.2, 32.6, 67.4, 76.5, 267.7 ppm; elemental
2
3
3
J
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
J
A
H
U
G
R
N
U
G
2
), 3.62 (m,
À1
analysis calcd (%) for C17
H
35
N
4
Nd (M=439.73 gmol ): C 46.43, H 8.02,
3
3
8
CH
J
A
H
U
G
R
N
U
G
J AHCTUNGTERNNUNG( H,H)=9.2 Hz, 1H;
N 12.74; found: C 41.93, H 7.77, N 12.83.
13
1
2
CHCH
2
8
3
3
[
Sm
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C
3
H
5
)
2
] (1-Sm): A solution of [Sm
A
H
N
T
E
N
N
(h -C
3
H
5
)
3
(1,4-di-
(CH
(CH
3
3
2
2
2
2
1
oxane)] (600 mg, 1.66 mmol) in THF (10 mL) was treated with a solution
2
2
2
Chem. Eur. J. 2011, 17, 15014 – 15026
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15023

J. Okuda et al.
1
1
2
2
45.4 Hz; m-Ph), 139.3 (d, J(CF)=242.8 Hz; p-Ph), 149.3 (d, J(CF)=
(p(H
2
)=5 bar) and placed into an oil bath at 508C. The conversion was
1
1
41.9 Hz; o-Ph), 149.5 ppm (CH
2
CHCH
2
).
followed by H NMR for three days. H NMR ([D ]THF, 258C): d=
8
3
À4.58 (s, 6H; CH ), 0.30 (m, 2H; CH ), 1.24 (m, 2H; CH ), 1.76 (m, 2H;
[
(
Ce
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C
3
H
5
)
A
H
U
G
R
N
N
(thf)
2
][B(C
A
H
U
G
R
N
U
G
6
H
5
)
4
] (2-Ce): A solution of 1-Ce
3
2
2
CH
2
), 4.03 (m, 4H; CH
2
), 5.22 (s, 3H; CH
3
2
), 6.08 (m, 2H; CH ), 6.18 (m,
87 mg, 0.20 mmol) in THF (2.5 mL) was treated with a solution of
H][B(C ] (84 mg, 0.20 mmol) in THF (2.5 mL). After stirring
for 0.5 h, the solvent was removed under reduced pressure and the re-
1
3
1
2
4
H; CH
1.4 (CH
2
), 6.68 ppm (m, 2H; CH
2
); C{ H} NMR ([D
8
]THF, 258C): d=
). 68.9 ppm
[
NEt
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
6 5 4
H )
3
), 51.3 (CH
3
), 53.3 (CH
2
), 61.2 (CH ), 63.4 (CH
2
2
(
2
CH) .
maining product was washed with n-pentane (5ꢄ2.5 mL) to afford 2-Ce
(
144 mg, 0.157 mmol, 79%) as a yellow powder. Diffraction-quality crys-
Typical procedure for the hydrodeoxygenation of furanics: a) [D ]THF or
8
tals of 2-Ce were obtained from an n-pentane/THF mixture at À408C.
[D ]benzene (0.5 mL) was added to complex 1-Y, 1-La, 1-Ce, 1-Nd, or
1-Sm (0.045 mmol) in a Teflon-screw-top pressure NMR tube (Wilmad).
6
1
H NMR ([D
8
]THF, 258C): d=À18.03, À17.83, À8.75–3.24, 0.91, 1.34,
1
.79, 3.62, 6.58, 6.84, 7.91, 9.91, 14.80, 22.92, 36.48, 45.92, 66.15 ppm;
After dissolution of all solid, furan (3.4 mL, 0.045 mmol), 2-methylfuran
(4.1 mL, 0.045 mmol), or 2,5-dimethylfuran (4.9 mL, 0.045 mmol) was
added. The NMR tube was cooled with liquid nitrogen, connected to a
Schlenk-line, and evacuated. The NMR tube was then warmed to room
temperature and after the solution had melted, pressurized with hydro-
1
3
1
C{ H} NMR ([D
1.6 (CH ), 35.1 (CH
25.3 (quart,
65.2 ppm (quart,
8
]THF, 258C): d=11.8 (CH
), 37.3 (CH ), 54.6 (CH ), 68.2 (a-thf), 121.5 (p-Ph),
(B,C)=2.6 Hz; m-Ph), 137.2 (m,
3 3
), 23.2 (CH ), 26.3 (b-thf),
3
1
1
2
2
2
2
3
2
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
JACHTUNGTRENNUNG
1
JACHTUNGTRENNUNG
1
1
1
ed). B{ H} NMR ([D
calcd (%) for C46
8
]THF, 258C): d=À7.03 ppm; elemental analysis
gen (p(H )=5.5 bar) and placed into an oil bath at 508C. b) Alternative
2
À1
H
66
N
4
BCeN
4
O
2
(M=857.43 gmol ): C 64.40, H 7.75, N
procedure with prior hydrogenation of 1-La to 3-La: [D ]THF (0.5 mL)
8
6
.53; found: C 59.04, H 7.34, N 7.13.
was added to complex 1-La (0.045 mmol) in a Teflon-screw-top pressure
3
[
Nd
tion of LH (28 mg, 0.13 mmol) was added to a solution of [Nd
(thf) ][B(C ] (100 mg, 0.13 mmol) in THF (2 mL). The reaction mix-
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C
3
H
5
)
A
H
U
G
R
N
N
(thf)
2
][B
A
H
U
G
R
N
U
G
6
H
5
)
4
] (2-Nd): A THF (2 mL) solu-
NMR tube (Wilmad). The NMR tube was cooled with liquid nitrogen,
connected to a Schlenk line, and evacuated. The NMR tube was then
warmed to room temperature and after the solution had melted, pressur-
3
3 5 2
AHCTUNGTRENUNNG( h -C H ) -
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
6 5 4
H )
ture was stirred for 1.5 h, then all volatiles were removed under reduced
ized with hydrogen (p(H
for three days. All solvents were then removed under reduced pressure.
After dissolution of all solid in [D ]THF (0.5 mL), 2-methylfuran (7 mL,
2
)=5.5 bar) and placed into an oil bath at 508C
pressure to afford 2-Nd as a light green powder (75 mg, 0.08 mmol,
1
6
(
1%). H NMR ([D
8
]THF, 258C): d=À42.27 (br s), À31.14 (br s), 1.83
8
m; b-thf), 3.63 (m; a-thf), 5.78 + 6.26 (2ꢄbr s; o-Ph+m-Ph), 6.48 (br s;
p-Ph), 16.51 (br s), 51.14 ppm (br s); C{ H} NMR ([D
0.092 mmol) was added. The NMR tube was cooled with liquid nitrogen,
connected to a Schlenk-line, and evacuated. The NMR tube was then
warmed to room temperature and after the solution had melted, pressur-
ized with hydrogen (5.5 bar), placed into an oil bath at 508C for 22 days,
1
3
1
8
]THF, 258C): d=
2
1
6.5 (b-thf), 68.2 (a-thf), 121.2 (p-Ph), 124.87 (m-Ph), 135.9 (o-Ph),
1
63.7 ppm (quart,
J ACHTUNGTRENNUNG( B,C)=49.4 Hz; i-Ph) (allyl signals were not detect-
1
ed); elemental analysis calcd (%) for
C
42
H
58BN
4
NdO (M=
and removed from the oil bath every day for H NMR measurement.
À1
1
579.98 gmol ): C 64.69, H 6.85, N 6.56; found: C 59.58, H 7.01, N 6.84.
+
+
2
-Pentene: MS: m/z (%): 70 (38) [M ], 55 (100) [M ÀCH
3
]; cis-2-pen-
1
3
[
Y
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(m-H)
2
]
3
A
H
U
G
R
N
U
G
8
]THF (0.5 mL) was added to 1-Y
tene: H NMR ([D ]THF, 258C): d=0.94 (t, J ACTHNGUTERNNU(G H,H)=7.3 Hz, 3H; CH ),
1.61 (m, J ACHTUNGTRENNUNG( H,H)=4.6 Hz, 3H; CH ), 1.95 (m, 2H; CH ), 5.39 ppm (m,
3 2
2H; CH); H NMR ([D ]benzene, 258C): d=0.92 (t, J ACHTUNGRTNENUN(G H,H)=7.3 Hz,
J ACHTUNGTERNNUG( H,H)=5.0 Hz, 3H; CH ), 1.96 (m, 2H; CH ),
3 2
5.42 ppm (m, 2H; CH); trans-2-pentene: H NMR ([D ]THF, 258C): d=
3 3
ACTHUNGERTNNUN(G H,H)=7.3 Hz, 3H; CH ), 1.58 (m, J ACHTNUGTRENNUNG( H,H)=5.0 Hz, 3H; CH ),
1.95 (m, 2H; CH ), 5.39 ppm (m, 2H; CH); H NMR ([D ]benzene,
8
3
3
(
40 mg, 0.104 mmol) in a Teflon-screw-top pressure NMR tube (Wilmad).
1
3
The NMR tube was cooled with liquid nitrogen, connected to a Schlenk
line, and evacuated. The NMR tube was then warmed to room tempera-
ture and after the solution had melted, pressurized with hydrogen
6
3
3H; CH ), 1.51 (m,
3
1
8
3
3
(
p(H
2
)=5 bar) and placed into an oil bath at 508C. The conversion was
0.94 (t, J
1
1
1
followed by
H NMR spectroscopy for three days.
H NMR
); 2.47
), 2.65
(H,H)=
(H,H)=
2
6
3
3
(
(
(
1
5
[D
6
]benzene, 258C): d=2.09 (m, 2H; CH ), 2.27 (m, 4H; CH
2
2
258C): d=0.92 (t, J
3
ACTHUNGTRENN(NUG H,H)=7.3 Hz, 3H; CH ), 1.58 (m, J ACHTUNGTRNEGUN
2
3
dd, J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=10.7, J
), 2.84 (s, 6H; CH
(H,H)=4.3 Hz, 2H; CH
.6 Hz, 2H; CH ), 3.90 (m, 2H; CH
]benzene, 258C) d=46.3 (CH
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H,H)=4.3 Hz, 2H; CH
2
), 2.62 (m, 2H; CH
2
3H; CH ), 1.96 (m, 2H; CH ), 5.42 ppm (m, 2H; CH).
3
2
2
3
s, 3H; CH
3
3
), 3.20 (ddd,
J
A
H
U
G
E
N
N
(H,H)=12.1,
J
J
A
H
N
T
E
U
G
+
1
2
-Butene: MS: m/z (%): 56 (100) [M ]; cis-2-butene: H NMR
3
2
3
1.8,
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
), 3.46 (dd,
J
A
H
U
G
R
N
U
G
3
(
[D
6
]benzene, 258C): d=1.50 (d,
J
A
H
U
G
R
N
U
G
3
), 5.47 ppm
1
3
1
2
2
), 6.45 ppm (m, 2H; YH); C{ H}
), 50.1 (CH ), 52.3 (CH ), 56.3
); elemental analysis calcd (%) for
1
(
m, 2H; CH); trans-2-butene: H NMR ([D
6
NMR ([D
CH ), 57.1 (CH
6
3
3
2
3
J ACHTUNGTERNN(UGN H,H)=4.9 Hz, 6H; CH
3
(
C
2
2
), 63.3 ppm (CH
2
+
+
+
À1
3-Hexene: MS: m/z (%): 84 (50) [M ], 69 (30) [M ÀCH
3
], 55 (100) [M
99
H
241
N
36
Y
3
(M=912.79 gmol ): C 43.42, H 8.94, N 18.41; found: C
1
3
À2CH
3
]; cis-3-hexene: H NMR ([D
6
]benzene, 258C): d=0.92 (t, J-
4
3.99, H 7.93, N 16.37.
3
A
H
U
G
R
N
U
G
3
), 1.57 (d, J
A
H
U
G
R
N
U
G
2
), 5.39 ppm
(H,H)=5.5 Hz, 4H; CH ),
]THF or
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[La (Me TACD) (m-H)
4
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
4
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
6
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(m
3
-H)
A
H
U
G
R
N
N
(m
4
-H)] (3-La): [D
8
]THF (0.5 mL) was
1
(
6
added to 1-La (40 mg, 0.092 mmol) in a Teflon-screw-top pressure NMR
tube (Wilmad). The NMR tube was cooled with liquid nitrogen, connect-
ed to a Schlenk line, and evacuated. The NMR tube was then warmed to
room temperature and after the solution had melted, pressurized with hy-
3
3
J
A
H
U
G
E
N
N
3
), 1.52 (d,
J
A
H
U
G
R
N
U
G
2
5
8
[
D
6
drogen (p(H
sion was followed by H NMR spectroscopy for three days. H NMR
[D ]THF, 258C): d=2.21 (m, 4H; CH ), 2.54 (br s, 4H; CH ), 2.63 (s,
H; CH ), 2.78 (m, 4H; CH ), 2.79 (s, 6H; CH ), 2.99 (m, 2H; CH ),
.39 (m, 2H; CH ), 10.52 ppm (br s, 2H; LaH); C{ H} NMR ([D ]THF,
58C): d=45.2 (CH ), 49.0 (CH ), 52.8 (CH ), 56.6 (CH ), 57.1 (CH ),
0.8 ppm (CH ). X-ray diffraction quality crystals of 3-La were collected
(63 mg,
.58 mmol) for 1 h in benzene at RT, followed by cooling of the reaction
2
)=5 bar) and placed into an oil bath at 508C. The conver-
1
1
(
(
8
2
2
1
action was followed by H NMR spectroscopy and GC-MS analysis.
3
3
2
6
3
2
3
3
2
1
1
1
Bis(furan-2-ylmethoxy)
4.67 (s, 4H; CH
A
H
U
G
R
N
N
(phenyl)silane: H NMR ([D
6
]benzene, 258C): d=
2
8
2
), 5.25 (s, 1H; SiH), 6.02 (m, 2H; C4-H), 6.08 (m, 2H;
3
3
2
2
2
C3-H), 7.06 (m, 2H; C5-H), 7.17 (m, 2H; m-Ph+p-Ph), 7.71 ppm (m,
1H; o-Ph).
2
after reaction of 1-La (169 mg, 0.40 mmol) with PhSiH
3
1
0
Tris(furan-2-ylmethoxy)
A
H
U
G
R
N
U
G
6
mixture over one week at 58C.
4
.76 (s, 6H; CH
2
), 6.02 (m, 3H; C4-H), 6.05 (m, 3H; C3-H), 7.06 (m,
D
[
La
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(Me
3
TACD)D
2
] (3 -La): This compound was prepared following the
3H; C5-H), 7.17 (m, 2H; m-Ph+p-Ph), 7.77 ppm (m, 1H; o-Ph).
2
same procedure as for 3-La but using D .
Typical procedure for the hydrogenation of furfural in a reactor: In the
glovebox, toluene (4 mL) was added to complex 4-Y (5 mg, 0.01 mmol),
1-La (5 mg, 0.01 mmol), or 3-Y (9 mg, 0.01 mmol) in a miniclave with
PTFE cover (Bꢁchi). After dissolution of all solid, furfural (38 mg,
0.40 mmol) was added, and the reactor was closed and pressurized with
[
Sm
3 2 8
ACHTUNGTRENNUNG( Me TACD)H ] (3-Sm): [D ]THF (0.5 mL) was added to 1-Sm
(
18 mg, 0.04 mmol) in a Teflon-screw-top pressure NMR tube (Wilmad).
The NMR tube was cooled with liquid nitrogen, connected to a Schlenk
line, and evacuated. The NMR tube was then warmed to room tempera-
ture and after the solution had melted, pressurized with hydrogen
2
hydrogen (p(H )=5.5–7.0 bar). After 1–3 days of stirring at ambient tem-
15024
www.chemeurj.org
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 15014 – 15026

Rare-Earth Metal Complexes Supported by a Macrocyclic Ligand
perature, the pressure was released and the reactor was opened in a
FULL PAPER
[9] P. A. Cox in The Elements: Their Origin, Abundance, and Distribu-
tion, Oxford University Press, Oxford, UK, 1989.
1
fume hood. For H NMR analysis, a 0.1 mL sample of the reaction solu-
tion was taken and 0.5 mL [D
was analyzed by GC-MS.
8
]THF added. The neat reaction mixture
[10] E. Abinet, T. P. Spaniol, J. Okuda, Chem. Asian J. 2011, 6, 389–391.
[11] V. Boldrini, G. B. Giovenzana, R. Pagliarin, G. Palmisano, M. Sisti,
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Soc. Dalton Trans. 2000, 3034–3040.
+
+
2
-Furfuryl alcohol (C): MS: m/z (%): 98 (100) [M ], 97 (33) [M À1], 81
+ À + +
(
49) [M ÀOH ], 70 (49) [M ÀCO], 69 (49) [M ÀCO], 53 (53).
+
+
Furfuryl 2-furoate (D): MS: m/z (%): 192 (1) [M ], 97 (13) [M
+
+
[13] r(H)=rÀr(D); r was calculated from the mean distance between the
ÀC
5
H
3
O
2
], 95 (32) [M ÀC
5
H
5
O
2
], 81 (100) [M ÀC
5 3 3
H O ].
four nitrogen atoms and the centroid built by N1, N2, N3, and N4.
Typical procedure for the hydrogenation of furfural in a pressure NMR
3
r(D) is the radius of the donor atoms. r(N
A
H
U
G
E
N
N
(sp )) is used as a simplifi-
tube: A Teflon-screw-top pressure NMR tube (Wilmad) was filled with a
À1
cation for all cavity calculations because N1 (amido nitrogen) is an
stock solution of 4-Y in [D
8
]THF (0.15 mL, 0.3 mL; c=0.05 mmolmL ),
2
3
3
2
sp –sp borderline case and r(N ACHNTUGRENNUG( sp ))=0.72 ꢃ and r(N ACHTGNUTRENNUN(G sp ))=0.66 ꢃ
a
2
stock solution of furfural in [D
8
]THF (0.15 mL, 0.3 mL; c=
À1
do not differ much; a) L. A. Drummond, K. Henrick, M. J. L. Kana-
gasundaram, L. F. Lindoy, M. McPartlin, P. A. Tasker, Inorg. Chem.
.0 mmolmL ), and [D
8
]THF (0.3 mL, 0 mL). The NMR tube was
cooled with liquid nitrogen, connected to a Schlenk line, and evacuated.
The NMR tube was then warmed to room temperature and after the so-
1
982, 21, 3923–3927; b) V. J. Thom, C. C. Fox, J. C. A. Boeyens,
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2
lution had melted, pressurized with hydrogen (p(H )=5 bar) and placed
into an oil bath at 508C. The conversion was followed by H NMR spec-
troscopy and determined by GC-MS analysis after six days.
1
Typical procedure for hydride transfer: [D
complex 3-Y (1:2, 66 mg, 0.072 mmol; 1:4, 33 mg, 0.036 mmol; 1:8, 17 mg,
.019 mmol; 1:13, 10 mg, 0.011 mmol) in a J. Young NMR tube. After dis-
8
]THF (0.6 mL) was added to
0
[
[
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1
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1937–11947.
We gratefully acknowledge financial support from the Cluster of Excel-
lence RWTH Aachen “Tailor-Made Fuels from Biomass”. Dr. K. Beck-
erle is gratefully thanked for measurements as well as Dr. Y. Wan and
Prof. Dr. U. Englert for recording the X-ray data.
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Received: July 12, 2011
Published online: December 1, 2011
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