Chiral benzamidinate ligands in rare-earth-metal coordination chemistry

Article abstract of DOI:10.1002/chem.201202457

The treatment of the recently reported potassium salt (S)-N,N'-bis-(1- phenylethyl)benzamidinate ((S)-KPEBA) and its racemic isomer (rac-KPEBA) with anhydrous lanthanide trichlorides (Ln=Sm, Er, Yb, Lu) afforded mostly chiral complexes. The tris(amidinate) complex [{(S)-PEBA}₃Sm], bis(amidinate) complexes [{Ln(PEBA)₂(μ-Cl)}₂] (Ln=Sm, Er, Yb, Lu), and mono(amidinate) compounds [Ln(PEBA)(Cl)₂(thf) _n] (Ln=Sm, Yb, Lu) were isolated and structurally characterized. As a result of steric effects, the homoleptic 3:1 complexes of the smaller lanthanide atoms Yb and Lu were not accessible. Furthermore, chiral bis(amidinate)-amido complexes [{(S)-PEBA}₂Ln{N(SiMe ₃)₂}] (Ln=Y, Lu) were synthesized by an amine-elimination reaction and salt metathesis. All of these chiral bis- and tris(amidinate) complexes had additional axial chirality and they all crystallized as diastereomerically pure compounds. By using rac-PEBA as a ligand, an achiral meso arrangement of the ligands was observed. The catalytic activities and enantioselectivities of [{(S)-PEBA}₂Ln{N(SiMe₃) ₂}] (Ln=Y, Lu) were investigated in hydroamination/cyclization reactions. A clear dependence of the rate of reaction and enantioselectivity on the ionic radius was observed, which showed higher reaction rates but poorer enantioselectivities for the yttrium compound. Copyright

Full text of DOI:10.1002/chem.201202457

FULL PAPER
DOI: 10.1002/chem.201202457
Chiral Benzamidinate Ligands in Rare-Earth-Metal Coordination Chemistry
Paul Benndorf, Jochen Kratsch, Larissa Hartenstein, Corinna M. Preuss, and
Peter W. Roesky*[a]
Abstract: The treatment of the recently
reported potassium salt (S)-N,N’-bis-(1-
effects, the homoleptic 3:1 complexes
of the smaller lanthanide atoms Yb
and Lu were not accessible. Further-
more, chiral bis(amidinate)–amido
tional axial chirality and they all crys-
tallized as diastereomerically pure
compounds. By using rac-PEBA as a
ligand, an achiral meso arrangement of
the ligands was observed. The catalytic
activities and enantioselectivities of
phenylethyl)benzamidinate
((S)-
KPEBA) and its racemic isomer (rac-
KPEBA) with anhydrous lanthanide
trichlorides (Ln=Sm, Er, Yb, Lu) af-
forded mostly chiral complexes. The
complexes [{(S)-PEBA}2Ln{NACTHNUTRGNE(UNG SiMe3)2}]
(Ln=Y, Lu) were synthesized by an
amine-elimination reaction and salt
metathesis. All of these chiral bis- and
tris(amidinate) complexes had addi-
[{(S)-PEBA}2Ln{NACHTNUGTRNEUNG(SiMe3)2}] (Ln=Y,
tris(amidinate)
PEBA}3Sm], bis(amidinate) complexes
[{Ln(PEBA)2A(m-Cl)}2] (Ln=Sm, Er,
Yb, Lu), and mono(amidinate) com-
pounds [Ln(PEBA)(Cl)2A(thf)n] (Ln=
complex
[{(S)-
Lu) were investigated in hydroamina-
tion/cyclization reactions. A clear de-
pendence of the rate of reaction and
enantioselectivity on the ionic radius
was observed, which showed higher re-
action rates but poorer enantioselectiv-
ities for the yttrium compound.
A
CHTUNGTRENNUNG
Keywords: amidinate · hydroami-
nation · lanthanides · ligand effects ·
rare-earth metals
A
CHTUNGTRENNUNG
Sm, Yb, Lu) were isolated and structur-
ally characterized. As a result of steric
Introduction
merous catalytic applications of lanthanide–amidinate com-
plexes, such as the polymerization of ethene[5] and iso-
prene,[6] hydroboration,[7] hydrosilylation,[8] and intramolecu-
lar hydroamination/cyclization reactions,[9] have been repor-
ted.[2b,3b,10]
Surprisingly, relatively few chiral amidines are known in
coordination chemistry (Scheme 1) and only complexes of
Group 4 metals,[11] molybdenum,[12] nickel,[12,13] and rhodi-
um,[14] but no lanthanide complexes had been presented in
the literature before we entered this field.[15]
Amidinates and their closely related guanidinates are a
well-established class of N-chelating ligands that form com-
plexes with almost all metals in the periodic table.[1] In gen-
eral, amidinates are monoanionic nitrogen-donor ligands of
the formula [RCACHTUNGTRENNUNG
(NR’)2]À. Because substituents R and R’
can be easily varied in numerous ways, the steric and elec-
tronic properties of these ligands can be effectively tuned.
Beside their ease of accessibility, this high flexibility in
ligand design is one factor that makes amidinates very popu-
lar as ligands in coordination chemistry. The versatility of
amidinates as ligands is also reflected in the chemistry of
the rare-earth elements. The rare-earth-metal chemistry of
amidinate was pioneered by Edelmann and co-workers
about two decades ago.[2] Since then, the number of publica-
tions in this area has been rapidly expanding.[2b,3] The most
intensely studied amidinate ligand, N,N’-bis-(trimethylsilyl)-
benzamidinate,[4] has been found to stabilize lanthanide
complexes in all three of its accessible oxidation states (+II,
+III, +IV).[2b] This ligand can also be used to synthesize
mono-, bis-, and tris(amidinate) complexes. Moreover, nu-
[a] Dr. P. Benndorf, Dipl.-Chem. J. Kratsch, L. Hartenstein,
Dipl.-Chem. C. M. Preuss, Prof. Dr. P. W. Roesky
Institut fꢀr Anorganische Chemie
Scheme 1. Known chiral amidinates that are used as ligands in coordina-
tion chemistry.
Karlsruher Institut fꢀr Technologie (KIT)
Engesserstrasse 15, 76131 Karlsruhe (Germany)
Fax : (+49)721-608-44854
Recently, we reported an improved synthesis of the chiral
amidine N,N’-bis-(1-phenylethyl)benzamidine (HPEBA) and
its corresponding lithium- and potassium salts (LiPEBA and
KPEBA, respectively).[15a] KPEBA was synthesized by the
treatment of KH with HPEBA in boiling THF (Scheme 2).
E-mail: roesky@kit.edu
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201202457.
Chem. Eur. J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
1
&
ÞÞ
These are not the final page numbers!

Scheme 2. Synthesis of (S)-KPEBA from KH and (S)-HPEBA.[15a]
HPEBA was first reported about 30 years ago by Brunner
et al.[12,14b] By using this chiral ligand, we communicated the
first chiral rare-earth–amidinate complexes and determined
their catalytic activities and enantioselectivities in hydroami-
nation reactions.[15b,16] Based on these results, herein, we
report a full account of the reactivity of the PEBA ligand in
its coordination chemistry of rare-earth elements, including
structural investigations. Also, the influence of the ionic
radius of different lanthanide metals onto the coordination
of the PEBA ligand is reported. Moreover, the application
of some selected compounds as catalysts in the enantioselec-
tive intramolecular hydroamination reactions of non-activat-
ed terminal amino olefins is shown. In our investigation, we
focused on the enantiopure version of the PEBA ligand,
but, in some cases, its racemic form was also used because it
tended to crystallize more easily. Moreover, the enantiopure
and racemic forms had an influence on the chirality of the
metal center. By using both forms, a comparison was possi-
ble.
Scheme 3. Synthesis of mono- and bis(amidinate)–chloro complexes.
molecules in the unit cell (Figure 1). The samarium atom is
sevenfold coordinated by the PEBA ligand, two chloride
atoms, and three molecules of THF in a distorted pentago-
nal-bipyramidal fashion. The N1-C1-N2 angle (114.4(2)8)
Results and Discussion
Figure 1. Solid-state structure of complex 1; hydrogen atoms are omitted
In a systematic approach, we synthesized mono-, di-, and tri-
substituted amidinate complexes of the rare-earth ele-
ments.[16]
À
for clarity. Selected bond lengths [ꢂ] and angles [8]: C1 N1 1.334(4),
À
À
À
À
À
C1 N2 1.337(3), C1 C2 1.510(4), C1 Sm 2.887(3), C8 N1 1.466(3), C8
À
À
À
À
C9 1.517(4), C8 C10 1.527(4), C16 N2 1.468(3), C16 C17 1.516(4), C16
C18 1.528(4), N1 Sm 2.437(2), N2 Sm 2.440(2), O1 Sm 2.486(2), O2
À
À
À
À
À
À
À
Sm 2.580(2), O3 Sm 2.512(2), Cl1 Sm 2.6705(8), Cl2 Sm 2.6685(8); N1-
C1-N2 114.4(2), N1-C1-C2 123.1(2), N2-C1-C2 122.5(2), N1-C1-Sm
57.17(14), N2-C1-Sm 57.30(14), N1-C8-C9 109.9(2), N1-C8-C10 112.4(2),
C9-C8-C10 112.6(3), N2-C16-C17 109.5(2), N2-C16-C18 112.3(2), C17-
C16-C18 112.5(2), C1-N1-C8 118.6(2), C1-N1-Sm 95.4(2), C8-N1-Sm
145.7(2), C1-N2-C16 118.5(2), C1-N2-Sm 95.2(2), C16-N2-Sm 146.3(2),
N1-Sm-N2 54.84(8), N1-Sm-O1 81.62(8), N2-Sm-O1 136.17(7), N1-Sm-
O3 137.72(7), N2-Sm-O3 83.39(7), O1-Sm-O3 140.43(7), N1-Sm-O2
151.39(7), N2-Sm-O2 153.76(7), O1-Sm-O2 69.86(7), O3-Sm-O2 70.62(7),
N1-Sm-Cl2 93.33(5), N2-Sm-Cl2 98.39(5), O1-Sm-Cl2 87.93(4), O3-Sm-
Cl2 85.91(4), O2-Sm-Cl2 83.65(4), N1-Sm-Cl1 99.60(5), N2-Sm-Cl1
94.42(5), O1-Sm-Cl1 87.50(4), O3-Sm-Cl1 88.87(4), O2-Sm-Cl1 81.87(4),
Cl2-Sm-Cl1 165.51(2).
Mono- and bis(amidinate)–chloro complexes: The mono-
(amidinate)–dichloro complexes of [LnACHTNUGTRENNUG(PEBA)(Cl)2ACHTUNGTERN(NUGN thf)n]
(Ln=Sm (1) , n=3; Ln=Yb (2), Lu (3), n=2) were ob-
tained by the reactions of anhydrous lanthanide trichlorides
with (S)- (Ln=Yb, Lu) and rac-KPEBA (Ln=Sm) in THF
at room temperature (Scheme 3). In the case of samarium,
the ligand had to be added dropwise to the suspension of
SmCl3 to avoid the formation of higher substituted species.
This observation was due to the larger ionic radius of sama-
rium compared to ytterbium and lutetium.[17] Complexes
with the larger lanthanides, lanthanum and cerium, could
not be obtained by using our synthetic approach.
À
À
À
Single crystals of compounds 1, 2, and 3 were obtained by
the slow diffusion of n-pentane into a solution of the com-
plexes in THF. Single crystals of the samarium compounds
were only obtained for the achiral complex, which was syn-
thesized by using rac-KPEBA. The enantiomerically pure
analogue could also be obtained in situ (see below) but
single crystals could not be grown. The racemic form of
compound 1 crystallizes in the space group P21/c with four
and the C1 N distances (C1 N1 1.334(4) ꢂ, C1 N2
1.337(3) ꢂ) are in the expected range.[15b]
1
In the H NMR spectrum of compound 1, very broad sig-
nals were observed owing to the paramagnetism of the sa-
marium atom, which resulted in a non-characteristic spec-
trum.
Isostructural compounds 2 and 3 crystallize in the chiral
space group C2 with two molecules in the unit cell
&
2
&
www.chemeurj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Benzamidinates in Rare-Earth-Metal Coordination Chemistry
FULL PAPER
Figure 2. Solid-state structure of compound 3; hydrogen atoms are omit-
ted for clarity. Selected bond lengths [ꢂ] and angles [8] (data for the iso-
Figure 3. Solid-state structure of compound 6; hydrogen atoms are omit-
ted for clarity. Selected bond lengths [ꢂ] and angles [8] (data for isostruc-
À
À
structural compound
2 are also given): 3: C1 N 1.334(4), C1 Lu
À
À
À
À
2.743(4), C6 N 1.474(5), C6 C8 1.519(5), C6 C7 1.525(5), N Lu
À
À
tural compounds 4 and 7 are also given): 6: C1 N1 1.330(6), C1 N2
À
À
2.303(3), O Lu 2.281(2), Cl Lu 2.5341(10); N-C1-N 113.8(4), N-C1-C2
123.1(2), N-C1-Lu 56.9(2), C2-C1-Lu 180.0 (1), C8-C6-C7 111.8(3), N-C6-
C7 109.3(3), N-C6-C8 110.0(3), C1-N-Lu 94.1(2), O-Lu-N 88.8(2), O-Lu-
N 85.8(2), O-Lu-Cl 87.9(12), O-Lu-Cl 96.05(12), Cl-Lu-Cl 101.17(6), N-
À
À
À
À
1.328(5), C1 C2 1.501(4), C1 Yb 2.729(3), C8 N1 1.480(4), C8 C9
À
À
À
À
1.536(6), C16 N2 1.472(5), C16 C17 1.528(7), N1 Yb 2.342(3), N2 Yb
À
À
2.273(3), Cl Yb 2.6724(7), Yb Yb 4.2046(6); N1-C1-N2 115.1(3), N1-C1-
C2 120.8(4), N2-C1-C2 124.1(4), N1-C1-Yb 59.0(2), N2-C1-Yb 56.1(2),
C2-C1-Yb 176.4(3), N1-C8-C9 110.1(3), N2-C16-C17 108.8(3), C1-N1-C8
119.5(3), C1-N1-Yb 91.8(2), C8-N1-Yb 148.7(2), C1-N2-C16 120.2(3), C1-
N2-Yb 95.0(2), C16-N2-Yb 144.7(3), Yb-Cl-Yb 103.75(3), N2-Yb-N1
À
À
À
À
Lu-N 58.0 (2); 2: C1 N 1.343(5), C1 C2 1.496(7), C1 Yb 2.754(5), C6
À
À
À
À
N 1.478(5), C6 C8 1.522(6), C6 C7 1.531(6), N Yb 2.300(4), O Yb
À
2.293(3), Cl Yb 2.5441(14); N-C1-N 112.7(5), N-C1-C2 123.7(2), N-C1-
Yb 56.3(2), N-C6-C8 111.0(3), N-C6-C7 108.9(4), C8-C6-C7 112.0(4), C1-
N-C6 120.6(3), C1-N-Yb 94.6(3), C6-N-Yb 144.6(3), O-Yb-O 172.4(3), O-
Yb-N 88.2(2), N-Yb-N 58.2(2), Cl-Yb-Cl 100.83(8).
À
À
À
58.13(11), Cl-Yb-Cl 76.25(3); 4: C1 N1 1.331(6), C1 N2 1.341(5), C1 C2
À
À
À
À
1.499(5), C1 Sm 2.831(3), C16 N2 1.478(5), C16 C17 1.527(6), C8 N1
À
À
À
À
1.477(4), C8 C9 1.527(6), N2 Sm 2.341(3), N1 Sm 2.441(3), Cl Sm
2.7682(7); N1-C1-N2 114.7(3), N1-C1-C2 124.3(4), N2-C1-C2 121.1(4),
À
N2-Sm-N1 56.06(11), Sm-Cl-Sm 103.74(3), Cl-Sm-Cl 76.26(3); 7: C1 N1
À
À
À
À
1.325(5), C1 N2 1.345(5), C1 C2 1.507(4), C1 Lu 2.725(3), C16 N2
(Figure 2). In each case, the central metal atom is coordinat-
ed by one PEBA ligand, two chloride atoms, and two THF
molecules in a distorted octahedral fashion. The two chlor-
ide atoms are coordinated in a cis arrangement (Cl-Yb-Cl’
100.83(8), Cl-Lu-Cl’ 101.17(6)) and are also coplanar to the
NCN plane. A crystallographic C2 axis through the phenyl
group at the central carbon atom of the PEBA ligand and
the lanthanide ion is observed. Thus, only half of the mole-
cule is located in the asymmetric unit. The distances be-
tween the lanthanide center and the chloride atoms are
À
À
À
À
1.483(4), C8 C9 1.547(5), C16 C17 1.521(6), C8 N1 1.482(4), N1 Lu
À
À
2.343(2), N2 Lu 2.256(3), Cl Lu 2.6648(6); N1-C1-N2 114.8(3) N1-C1-
C2 124.4(4), N2-C1-C2 120.8(4), N2-Lu-N1 58.51(9), Lu-Cl-Lu 103.81(3),
Cl-Lu-Cl 76.19(3).
We suggest that these signals are the result of a ligand-redis-
tribution reaction.
In the solid state, compounds 4, 5, 6, and 7 form dimers
that are bridged by two chlorine atoms (Figure 3). The ob-
served arrangement is similar to that of the comparable gua-
À
2.544(1) ꢂ (2) and 2.5341(10) ꢂ (3), the Ln N bond length
is 2.300(4) ꢂ in complex 2 and 2.303(3) ꢂ in complex 3. The
N-C1-N’ angles are 112.7(5)8 (2) and 113.8(4)8 (3) and the
N-Ln-N’ angles are 58.2(2)8 (2) and 58.0(2)8 (3).
nidinate complex, [({(Me3Si)2NCACTHNGUTERN(NUG NiPr)2}2SmCl)2], which is
also dimeric in the solid state.[18] Compounds 4, 6, and 7 are
isostructural and crystallize in the cubic space group I23
with six molecules in the unit cell. The asymmetric unit only
consists of a quarter of a molecule. Thus, two crystallograph-
ic C2 axes are observed in compounds 4, 6, and 7; one C2
The bis(amidinate)–chloro–lanthanide complexes [{Ln-
ACHTUNGTRENNUNG(PEBA)2ACHTUNGTRENNUNG(m-Cl)}2] (Sm (4), Er (5), Yb (6), Lu (7)) were syn-
thesized by a salt-metathesis reaction from LnCl3 and two
equivalents of either (S)- (Yb, Lu) or rac-KPEBA (Er).
Compounds 6 and 7 were best accessed in a one-pot synthe-
sis. The formation of their corresponding tris(amidinate)
complexes was prevented owing to steric reasons and, thus,
clean conversion into the bis complexes was observed. The
synthesis of compound 5 was less straightforward. The de-
sired compound could only be isolated in 10% yield. The
bis-
(amidinate) complex of the larger samarium cation could
not be obtained in a one-step reaction. To obtain compound
4, chiral mono(amidinate) complex 1 first had to be synthe-
sized in situ and then the second equivalent of KPEBA had
to be added dropwise into this solution. All of these com-
plexes have been characterized by standard analytical/spec-
troscopic techniques. In the NMR spectra of diamagnetic
compound 3, some additional signals were always observed.
À
axis is seen along the Cl Cl’ bond whereas the other one is
observed along the Ln Ln’ bond. Helical chirality is formed
À
along this axis. Only the helical L enantiomer[19] is observed,
thus showing that one diastereomer is exclusively formed in
the solid state. The lanthanide atoms are coordinated by
four nitrogen atoms of two ligands and two chloride anions.
The PEBA ligands of the same lanthanide atom are ar-
ranged in an eclipsed fashion to each other and in a stag-
gered orientated to the chlorine atoms. The ligand itself
À
binds asymmetrically to the lanthanide atoms; the Ln N
À
À
bond lengths differ by 0.06–0.10 ꢂ (Sm N1 2.441(3) ꢂ, Sm
À
À
À
N2 2.341(3) ꢂ, Yb N1 2.342(3) ꢂ, Yb N2 2.273(3) ꢂ, Lu
N1 2.343(2) ꢂ, Lu N2 2.256(3) ꢂ). We suggest that this
asymmetry is caused by steric repulsion between the ligands.
The N1 Cl distances (3.597 ꢂ (4), 3.443 ꢂ (6), 3.432 ꢂ (7))
À
À
À
are smaller than the N2 Cl distances (3.996 ꢂ (4), 3.864 ꢂ
Chem. Eur. J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
3
&
ÞÞ
These are not the final page numbers!

P. W. Roesky et al.
(6), 3.849 ꢂ (7)), which leads to larger repulsion between
À
À
the N1 and Cl atoms. The N1 C1 and N2 C1 distances are
almost equal and the N1-C1-N2 angles are similar to those
reported for the mono(amidinate) compounds (114.7(3)8
(4), 115.1(3)8 (6), 114.8(3)8 (7)).
Complex 5, which was synthesized by using rac-KPEBA,
¯
crystallizes in the centrosymmetric space group P1 with two
molecules of the complex and one molecule of n-pentane in
the unit cell. In contrast to rac-KPEBA and compound 1,
the crystal does not contain both enantiomers, but instead,
compound 5 crystallizes in an achiral meso arrangement. As
a result, a different orientation of the ligands is observed in
comparison to the chiral complexes, thus resulting in signifi-
cant changes in the bonding parameters. The chloro ligands
are now coordinated gauche to the PEBA ligands. The Cl-
Er-Cl angle (80.43(5)–80.54(5)8) is much larger than in the
chiral complexes (76.28 in all cases), and the two amidinate
ligands are coordinated almost symmetrically to the lantha-
Scheme 4. Synthesis of the tris(amidinate) complex 8.
À
À
À
nide atoms (Er N1 2.322(5) ꢂ, Er N2 2.314(6) ꢂ, Er N3
À
2.345(5) ꢂ, Er N4 2.314(5) ꢂ). The N-C-N angles are
(113.8(5)–114.9(6)8) in the same region as in compounds 4,
6, and 7.
All of the complexes were fully characterized by analyti-
cal spectroscopic techniques. The NMR spectra of diamag-
netic compound 7 showed characteristic sets of signals. Only
one signal was observed for each of the methine (1H NMR:
d=4.15 ppm; 13C{1H} NMR: d=58.3 ppm) and methyl
groups (1H NMR: d=1.44 ppm; 13C{1H} NMR: d=
Figure 4. Solid-state structure of compound 8; hydrogen atoms are omit-
À
ted for clarity. Selected bond lengths [ꢂ] and angles [8]: Sm N1 2.440(4),
À
À
À
À
À
Sm N2 2.437(4), N1 C1 1.325(6), N1 C8 1.484(6), N2 C1 1.333(6), N2
C16 1.480(5); N1-C1-N2 116.1(4), N1-Sm-N1’ 102.74(11), N1-Sm-N2
55.09(12), N1-Sm-N2’ 110.72(13), C1-N1-C8 118.3(4), C1-N2-C16
119.4(4).
1
21.7 ppm) in the H and 13C{1H} NMR spectra of compound
7, thus indicating that the ligands bind symmetrically to the
lanthanide atoms in solution. The chemical shifts of these
signals were in the range of those in KPEBA (methyl
PLATON.[20] A crystallographic C3 axis is observed through
the hexacoordinated samarium atom. Thus, only a third of
the molecule is located in the asymmetric unit. The four-
membered metallacycles that are formed by the ligand and
the samarium atom (N-C-N-Sm) are slightly rotated with re-
spect to each other, thereby forming a propeller-type struc-
ture. Thus, helical chirality, which is typical for trischelate
octahedral complexes, is formed. Because the ligands are
enantiomerically pure with an all-S configuration, in princi-
pal, two diastereomers could be formed. In the solid state,
we exclusively observed one diastereomer that had the L
configuration along the helical axis.[19] Thus, the molecule is
chiral at the metal center. In contrast to tris-{N,N’-
1
group: H NMR: d=1.30 ppm, 13C{1H} NMR: d=22.3 ppm;
methine group: 1H NMR: d=4.22 ppm, 13C{1H} NMR: d=
57.2 ppm).[15a]
Paramagnetic compound 4 shows two sets of signals in its
1
NMR spectra. In the H NMR spectrum, a quartet at d=
4.16 ppm (13C{1H} NMR: d=49.9 ppm) and a multiplet at
d=5.32 ppm (13C{1H} NMR: d=57.8 ppm) are observed for
the methine group. The methyl groups generate two dou-
blets in the 1H NMR spectrum at d=1.50 and 1.23 ppm
(13C{1H} NMR: d=26.5 and 22.1 ppm), respectively. In the
1H NMR spectrum, the signals for the aromatic protons
appear as multiplets between d=7.63–5.79 ppm. As result of
the paramagnetism, two protons could not be assigned and,
in the 13C{1H} NMR spectrum, the signals for the quaternary
carbon atoms were not observed.
bis(trimethylsilyl)benzamidinate}samariumACTHNURTGNEU(GN III), which was
reported by Edelmann and co-workers,[21] there are no
vacant coordination sites at the samarium atom. The center
metal atom is completely shielded by the ligands (Figure 5).
À
À
À
À
Tris(amidinate) complexes: The homoleptic samarium tris-
(amidinate) complex [{(S)-PEBA}3Sm] (8) was synthesized
The Sm N (Sm N1 2.440(4) ꢂ, Sm N2 2.437(4) ꢂ) and N
À
À
C1 (N1 C1 1.325(6) ꢂ, N2 C1 1.333(6) ꢂ) distances in
by amine-elimination from [Sm{N
(SiHMe2)2}
G
complex 8 are comparable to those observed in the mono-
HPEBA at room temperature in THF (Scheme 4).
ACHTUNGTREN(NGNU amidinate)–samarium complex (1). The N1-C1-N2 bite
Single crystals were obtained from a hot solution in THF.
Compound 8 crystallizes in the cubic space group P213 with
four molecules of compound 8 (Figure 4) and four molecules
of heavily disordered THF in the unit cell. The solvent mol-
ecules were suppressed by using the SQUEEZE routine in
angle (116.1(4)8) is slightly enlarged in comparison to com-
pound 1.
The H NMR spectrum signals of the paramagnetic com-
pound are broadened and shifted compared to those of the
(S)-KPEBA or bis(amidinate) complexes. There are broad
1
&
4
&
www.chemeurj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Benzamidinates in Rare-Earth-Metal Coordination Chemistry
FULL PAPER
Figure 5. Space-filling representation of the solid-state structure of com-
pound 8.
Scheme 5. Synthesis of amido complexes 9 and 10.
singlets for the methyl (d=À2.66 ppm) and methine groups
(d=3.33 ppm), both of which are shifted to higher field in
comparison to all of the diamagnetic compounds that are
discussed herein. Also, the signals for the aromatic protons
are broadened and appear in a region between d=8.98 and
6.88 ppm. In the 13C{1H} NMR spectrum, the methine group
also shows one signal (d=55.4 ppm), thus indicating that
the three ligands bind symmetrically at the samarium
center. The signals for the methyl group and the quaternary
carbon atom are not observed owing to the paramagnetism
of the samarium atom.
We could not isolate the corresponding tris(amidinate)–
lutetium complex [{(S)-PEBA}3Lu] by amine elimination or
salt metathesis. We suggest that the steric strain of the li-
gands in the potential [{(S)-PEBA}3Lu] complex would be
too high.
Figure 6. Solid-state structure of compound 9 (compound 10, which is not
shown here, is isostructural); hydrogen atoms are omitted for clarity. Se-
À
À
lected bond lengths [ꢂ] and angles [8]: Y N1 2.356(3), Y N2 2.353(4),
À
À
À
À
À
Y N3 2.366(4), Y N4 2.348(3), Y N5 2.266(4), Y Si1 3.5157(14), Y Si2
À
À
À
À
3.330(2), C1 N1 1.341(6), C1 N2 1.333(5), C8 N1 1.464(5), C16 N2
1.476(6), C24 N3 1.343(5), C24 N4 1.345(5), C31 N3 1.480(5), C39 N4
1.469(5), N5 Si1 1.698(4), N5 Si2 1.714(4); N1-Y-N2 57.74(12), N3-Y-N4
57.23(11), N1-C1-N2 116.5(4), N3-C24-N4 114.3(4), Si1-N5-Si2 122.7(2).
À
À
À
À
Amido complexes: Based on the knowledge that tris(amidi-
nate) complexes of the smaller rare-earth elements could
not be obtained, we developed a straightforward strategy to
synthesize chiral amido complexes with the composition
À
À
[{(S)-PEBA}2Ln{N
cial interested because the {N
G
dinated by the nitrogen atoms of the ligands. At first glance,
the molecules seems to have a non-crystallographic C2 axis
(SiMe3)2}À group is a potential
leaving group in the hydroamination/cyclization catalysis.[22]
We have previously communicated that chiral lutetium com-
along the N5 Y bond but, as already seen in the lutetium
À
complex (10), the symmetry is broken by the ligands. Helical
chirality (D enantiomer[19]) is observed along the pseudo-C2
axis. As observed for the previously described enantiopure
compounds, only one diastereomer crystallizes. One of the
PEBA ligands coordinates in a symmetrical manner to the
plex [{(S)-PEBA}2Lu{N
by salt metathesis from compound 7 and K{N
an amine-elimination reaction from (S)-HPEBA und [Lu{N-
(SiMe3)2}3] (Scheme 5).[15b] Because this latter route is more
ACHTUNGTRENNUNG
À
À
convenient and straightforward, we extended this route to
synthesize the corresponding chiral yttrium complex [{(S)-
yttrium atom (Y N1 2.356(3) ꢂ, Y N2 2.353(4) ꢂ), whereas
À
the other ligand is slightly asymmetrically coordinated (Y
À
À
PEBA}2Y{N
N
N3 2.366(4) ꢂ, Y N4 2.348(3) ꢂ). The Y N bond lengths in
compound 9 (2.266(4)–2.366(4) ꢂ), which are in the expect-
ed range,[23] are larger than in compound 10 (2.200(6)–
2.305(7) ꢂ), which is a result of the larger ionic radius of
Compounds 9 and 10 have been investigated by using
standard analytic/spectroscopic techniques and their solid-
state structures were investigated by single-crystal X-ray dif-
fraction. Because we have previously reported the structure
of compound 10, the structure of compound 9 is only briefly
discussed herein. Compound 9 is isostructural to complex 10
and crystallizes in the orthorhombic space group P212121
with four molecules of the metal complex in the unit cell
(Figure 6). The yttrium atom in compound 9 is fivefold coor-
the yttrium ion. The {NACTHNUTRGNEUNG
(SiMe3)2}À ligand coordinates asym-
À
metrically to the yttrium atom. Thus, the Y Si2 (3.330(2) ꢂ)
distance is smaller than the Y Si1 distance (3.5157(14) ꢂ),
thus resulting in different Y-N-Si bond angles of Y-N5-Si1
(124.3(2)8) and Y-N5-Si2 (112.8(2)8). This deviation is much
smaller than expected for an agostic interaction,[24] for ex-
À
Chem. Eur. J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
5
&
ÞÞ
These are not the final page numbers!

P. W. Roesky et al.
ample, in [(h5-C5Me5)2Y{CH
(SiMe3)2}] (Y-C-Si 138.6(4) and
showed good activity and all of the substrates were convert-
ed regiospecifically into their cyclic products under mild
conditions within reasonable reaction times. Although com-
pound 10 is more selective under the same reaction condi-
tions, higher ee values could be obtained for substrate 11a
with compound 9 (Table 1, entry 1) because the reaction al-
ready proceeded at room temperature. Substrate 12a
(Table 1, entry 2) could also be cyclized into its correspond-
ing spyrocycle at room temperature. In comparison, the lu-
tetium complex (10) needed elevated temperatures (608C)
to catalyze both reactions (Table 1, entries 1 and 2). Amino
alkenes 13a and 14a did not react at room temperature with
compound 9 as the catalyst; instead, a reaction temperature
of 608C was required.
The differences in the reactivities of substrates 11a–13a,
which contained different bulky substituents at the b posi-
tion to the amino group (Table 1, entries 1–3) can be ex-
plained by the Thorpe–Ingold effect.[32]
The ee values that were obtained by using compound 10
as the catalyst (13b: 75%, 14b: 33%) were significantly
higher than those with compound 9 (13b: 62%, 14b: 13%).
To the best of our knowledge, of all of the previously report-
ed lanthanide-catalyzed asymmetric intramolecular-hydroa-
mination reactions,[26h,j,q] only a very sophisticated thiol-
functionalized yttrium complex has shown higher ee values
for the conversion of substrate 13a.[28k] This catalyst was
Catalytic hydroamination/cyclization studies: The catalytic
hydroamination reaction is the addition of an organic amine
À
N H bond to a carbon–carbon multiple bond in one step.
This straightforward synthetic approach is superior to most
of the classical amine syntheses, which consist of multistep
reactions and, thus, involve the formation of byproducts and
large amounts of chemical waste. Although this reaction is
thermodynamically feasible under normal conditions, the
high reaction barrier is a significant problem for practical
use. Over the last two decades, a large number of hydroami-
nation catalysts that are based on s-, d-, and f-block metal
complexes have been developed. The progress in this area
over the last decade has been reviewed extensively.[22,26] The
enantioselective hydroamination reaction catalyzed by met-
allocene complexes of the rare-earth elements was pio-
neered in the 1990s by Marks and co-workers.[27] Nowadays,
a number of enantioselective non-metallocene rare-earth-el-
ement catalysts are known.[28] Parallel to this development,
enantioselective catalysts that are based on other metals
have also been reported.[26g,q,29] Nevertheless, there is still a
demand for catalysts that can enantioselectively convert a
broad range of substrates at moderate temperature with low
catalyst loadings.
Complexes 9 and 10 have been investigated
Table 1. Hydroamination of amino alkenes and amino alkynes catalyzed by compounds 9
and 10.[a]
as catalysts for the asymmetric intramolecular
hydroamination of amino alkenes and for the
hydroamination of amino alkynes. These ex-
periments were carried out under rigorously
anaerobic conditions in C6D6, either at room
temperature or at 608C, with a catalyst loading
of 5 mol%. The conversion was followed by
1H NMR spectroscopy with ferrocene as an in-
ternal standard and the ee values of the cy-
clized amino alkenes were determined by
19F NMR spectroscopy of their corresponding
Mosher (methoxy(trifluoromethyl)phenylace-
tyl) amides.[28l,m] In addition, the ee values were
also measured by chiral HPLC analysis of the
corresponding 1-naphthoyl amides, which af-
forded slightly higher values.[28h] The results are
shown in Table 1; for comparison, the values
for compound 10 are also shown.
In general, compound 9 showed higher cata-
lytic activity but lower enantioselectivity than
compound 10. This observation is in line with
earlier studies, which showed that the rate of
the reaction increased with increasing ionic
radius of the central metal atom.[30] The sug-
gested turnover-limiting step is the olefin-inser-
tion/cyclization step, which is sterically sensi-
tive.[30–31] Concomitant with the increasing
space around the metal center, the stereoselec-
tivity started to decrease. Compounds 9 and 10
Entry Substrate
Product
9
10
t
Yield[d] ee[e]
t
Yield[d] ee[e]
[h]
[%]
[%]
[h]
[%]
[%]
1
2
16[c]
14[c]
96
66 (S)[f]
9[b] 92
61 (S)[f]
97
66 (S)[f]
9[b] quant
69 (S)[f]
3
4
6.5[b] quant
62 (S)[f]
35[b] 92
75 (S)[f]
33 (R)[f]
20[b]
quant
13[g] (R)[f]
35[b] quant
40[c]
60[b]
45
96
5
6
–
–
108[c] 92
–
–
24[c]
quant
85[c] quant
Conditions: [a] Catalyst (15 mg, 5 mol%), C6D6; the results for compound 10 are given in
reference [15b]. [b] Reaction temperature: 608C. [c] Room temperature. [d] Determined
by 1H NMR spectroscopy with ferrocene as an internal standard. [e] Enantiomeric excess
determined by 19F NMR spectroscopy of Mosher amides. The values determined by chiral
HPLC analysis of the 1-naphthoyl amides were slightly higher. [f] Absolute configurations,
taken from reference [28l]. [g] Enantiomeric excess determined by chiral HPLC analysis
of 1-naphthoyl amides.
&
6
&
www.chemeurj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Benzamidinates in Rare-Earth-Metal Coordination Chemistry
only prepared in situ, by treating the protonated ligand with
[Y{NACHTUNGTRENNUNG(SiMe3)2}3], whereas compound 10 is well-characterized
and is much more easily accessible.
To evaluate the performance of our catalysts, we also in-
vestigated the hydroamination/cyclization reactions of two
internal alkynes (Table 1, entries 5 and 6), which formed
achiral Schiff bases as products. Quantitative formation of
spirocycle 16b was observed with both catalysts within 24 h
(9) and 85 h (10) at room temperature (Table 1, entry 6).
This difference in reactivity between catalysts 9 and 10 was
the same as that observed for the other reactions. In con-
trast, the cyclization of compound 15a (Table 1, entry 5)
stopped after 40 h at a conversion of 45% with catalyst 9,
probably owing to decomposition of the catalyst. To obtain
complete cyclization, a reaction temperature of 608C was
necessary.
FULL PAPER
800). All solvents for vacuum-line manipulations were stored in vacuo
over LiAlH4 in resealable flasks. Deuterated solvents were obtained from
Aldrich GmbH (99 atom% [D]) and were degassed, dried, and stored in
vacuo over Na/K alloy in resealable flasks. NMR spectra were recorded
on Bruker Avance II 300 MHz or 400 MHz NMR spectrometers. Chemi-
cal shifts are referenced to internal solvent and are reported relative to
tetramethylsilane. IR spectra were obtained on a Bruker Tensor 37. Mass
spectra were recorded at 70 eV on a Finnigan MAT 8200. Elemental
analysis was performed on an Elementar vario EL or microcube.
LnCl3,[33] [Ln{N
KPEBA,[15a]
G
ACHTUNGTRENNUNG
,
AHCTUNGTRENNUNG
(SiMe3)2}][15b] were prepared according to literature procedures.
ACHUTNGERN[NUG (PEBA)LnCl2ACHTUNGTREN(NNGU thf)n] (Ln=Sm (1), Yb (2), Lu (3)): THF (10 mL) was
condensed at À1968C onto a mixture of LnCl3 (0.71 mmol) and KPEBA
(237 mg, 0.65 mmol) and the reaction mixture was stirred overnight at
room temperature. The colorless precipitate was filtered off and the sol-
vent was removed in vacuo. The residue was washed with n-pentane and
the product was crystallized from THF/n-pentane.
ACHUTNRGENN[UG {(rac)-PEBA}SmCl2ACHTUNGTREN(NUGN thf)3] (1): Compound 1 was synthesized by the slow
addition of a solution of rac-KPEBA in THF (5 mL) to a suspension of
SmCl3 (183 mg, 0.71 mmol) in THF (10 mL). Yield: 98 mg (0.18 mmol,
28%) as yellow crystals; IR (ATR): n˜ =3056 (w), 3025 (w), 2921 (w),
2874 (w), 1631 (m), 1576 (w), 1490 (m), 1448 (m), 1380 (w), 1347 (w),
1305 (w), 1271 (w), 1207 (w), 1138 (w), 1070 (w), 1027 (w), 913 (w), 878
(w), 761 (m), 698 (s), 624 (w), 604 (w), 572 (w), 542 cmÀ1 (m); elemental
analysis calcd (%) for C23H23N2Cl2Sm·0.5C4H8O: C 51.35, H 4.65, N 4.79;
found: C 51.19, H 5.26, N 3.86.
Conclusion
We have synthesized a series of new chiral lanthanide–ami-
dinate complexes with the PEBA ligand. Whereas mono-,
bis-, and tris-substitution of the chloro ligand with the
PEBA ligand was possible by using samarium as the metal
center, for the smaller lanthanides, lutetium and ytterbium,
a homoleptic complex could not be obtained. As a conse-
quence, their bis(amidinate) complexes were readily obtain-
able in a one-step synthesis. The bis(amidinate) complexes
[{(S)-PEBA}YbCl2ACHTNUGTRNEUNG(thf)2] (2): This complex was prepared from YbCl3
(199 mg, 0.71 mmol) and (S)-KPEBA. Yield: 134 mg (0.24 mmol, 36%)
as orange crystals; IR (ATR): n˜ =3059 (w), 3027 (w), 2970 (w), 2926 (w),
2868 (w), 1625 (m), 1575 (w), 1492 (w), 1448 (w), 1381 (w), 1351 (w),
1308 (w), 1276 (w), 1206 (w), 1134 (w), 1082 (w), 1026 (w), 914 (w),760
(m), 697 (s), 572 (w), 541 cmÀ1 (m); elemental analysis calcd (%) for
C23H23N2Cl2Yb·2C4H8O: C 52.03, H 5.49, N 3.91; found: C 51.22, H 5.40,
N 3.68.
[{(S)-PEBA}2Ln{NACHTUNGTRENNUNG(SiMe3)2}] (Ln=Y, Lu) were synthesized
in one step from their corresponding lanthanide–amides. All
of these chiral bis- and tris(amidinate) complexes showed
additional axial chirality and they all crystallized as diaster-
eomerically pure compounds. By using rac-PEBA as a
ligand, an achiral meso arrangement of the ligands was ob-
served.
[{(S)-PEBA}LuCl2ACHTNUGTRNEUNG(thf)2] (3): This complex was prepared from LuCl3
(200 mg, 0.71 mmol) and (S)-KPEBA. Yield: 115 mg (0.16 mmol, 31%)
as yellow crystals; 1H NMR (300 MHz, [D8]THF, 238C): d=7.58–6.76
(m, 15H; Ph), 4.18–4.00 (m, 2H; CH), 1.38 ppm (d, 3J=6.8 Hz, 6H;
CH3). The complex slowly decomposed in solution and a precipitate was
formed; as result no clean NMR spectra could be obtained. IR (ATR):
n˜ =3059 (w), 3028 (w), 2956 (w), 2922 (w), 2855 (w), 1633 (m), 1576 (w),
1576 (w), 1488 (w), 1446 (m), 1415 (w), 1353 (w), 1305 (w), 1273 (w),
1209 (w), 1137 (w), 1074 (w), 1024 (w), 912 (w), 798 (w), 761 (m), 697 (s),
542 cmÀ1 (m); elemental analysis calcd (%) for C23H23N2Cl2Lu·2C4H8O:
C 51.89, H 5.48, N 3.90; found: C 51.91, H 5.17, N 3.78.
The catalytic activity of [{(S)-PEBA}2Ln{NACHTNUTRGENNG(U SiMe3)2}]
(Ln=Y, Lu) was investigated in the asymmetric intramolec-
ular hydroamination of amino alkenes and amino alkynes.
The yttrium complex showed good activity and all of the
substrates tested were converted regiospecifically into their
corresponding cyclic products under mild conditions within
good reaction times. The catalytic activity was higher and
the enantioselectivity was lower than that of the correspond-
ing lutetium complex. The lutetium complex was shown to
be a suitable catalyst for the asymmetric intramolecular hy-
droamination reaction and good enantiomeric excess values
were observed for some substrates.
AHCTUNGTERGN[NNU {(PEBA)2LnCl}2] (Ln=Sm (4), Er (5), Yb (6), Lu (7)): THF (10 mL)
was condensed at À1968C onto a mixture of LnCl3 (0.55 mmol) and
KPEBA (400 mg, 1.09 mmol) and the reaction mixture was stirred over-
night at room temperature. The colorless precipitate was filtered off and
the solvent was removed in vacuum. The residue was washed with n-pen-
tane and the product was crystallized from the specified solvent or sol-
vent mixture.
[({(S)-PEBA}2SmCl)2] (4): Compound 4 was synthesized in two steps. To
a suspension of SmCl3 (140 mg, 0.55 mmol) in THF (10 mL) was slowly
added a solution of (S)-KPEBA (200 mg, 0.55 mmol) in THF (5 mL) and
the mixture was stirred overnight at RT. Then, a second portion of (S)-
KPEBA (200 mg, 0.55 mmol) was dissolved in THF (5 mL), slowly added
to the reaction mixture, and stirred for 24 h at room temperature. The
product was crystallized from THF/n-pentane. Yield: 182 mg (0.22 mmol,
40%) as yellow crystals; 1H NMR (300 MHz, [D8]THF, 238C): d=7.64–
7.61 (m, 1H; Ph), 7.45–7.40 (m, 4H; Ph), 7.35–7.26 (m, 8H; Ph), 7.21–
7.12 (m, 5H; Ph), 7.03–6.95 (m, 5H; Ph), 6.90–6.87 (m, 3H; Ph), 5.82–
5.79 (m, 2H; Ph), 5.32 (m, 2H; Ph), 4.16 (q, 3J=6.5 Hz, 2H; CH), 1.50
(d, 3J=7.0 Hz, 6H; CH3), 1.23 ppm (d, 3J=6.5 Hz, 6H; CH3), two pro-
tons could not be assigned; 13C{1H} NMR (75 MHz, [D8]THF, 238C): d=
128.1 (Ph), 127.9 (Ph), 127.8 (Ph), 127.4 (Ph), 126.7 (Ph), 126.1 (Ph),
126.0 (Ph), 157.8 (Ph), 124.9 (Ph), 57.8 (CH), 49.9 (CH), 26.5 (CH3),
Experimental Section[16]
All of the manipulations of air-sensitive materials were performed with
the rigorous exclusion of oxygen and moisture in flame-dried Schlenk-
type glassware, either on a dual-manifold Schlenk line that was interfaced
to a high-vacuum (10À3 mbar) line or in an argon-filled MBraun glove
box. THF was distilled under a nitrogen atmosphere from potassium ben-
zophenone ketyl prior to use. Hydrocarbon solvents (toluene and n-pen-
tane) were dried by using an Mbraun solvent purification system (SPS-
Chem. Eur. J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
7
&
ÞÞ
These are not the final page numbers!

P. W. Roesky et al.
22.1 ppm (CH3), the signals for the quaternary carbon atoms were not
observed; IR (ATR): n˜ =3027 (w), 2955 (w), 2920 (w), 1633 (m), 1577
(w), 1487 (m), 1446 (m), 1407 (w), 1349 (w), 1305 (w), 1268 (w), 1208
(w), 1138 (w), 1073 (w), 1025 (w), 910 (w), 760 (m), 697 (s), 600 (w), 572
(w), 541 cmÀ1 (m); MS (EI, 70 eV): m/z (%): 826 (4) [MÀMe]+, 806 (29)
[MÀCl]+, 702 (4), 515 (24), 479 (11), 404 (6), 328 (100) [PEBA]+, 223
(100) [PEBAÀPhEt]+, 180 (100), 120 (100) [PhEtN]+, 105 (100) [PhEt]+,
91 (98) [Bz]+, 77 (100) [Ph]+, 57 (49), 42 (80) [C2H4N]+, 27 (22) [CHN]+;
elemental analysis calcd (%) for C46H46N4ClSm: C 65.72, H 5.52, N 6.66;
found: C 65.13, H 5.56, N 6.07.
[{(S)-PEBA}2Y{N
À1968C onto a mixture of [Y{N
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
HPEBA (362 mg, 1.1 mmol) and the reaction mixture was stirred over-
night at 1008C. The solvent was removed in vacuum and the product was
crystallized from hot n-heptane. Yield: 125 mg (0.14 mmol, 25%) as col-
orless crystals; 1H NMR (300 MHz, C6D6): d=7.45–7.00 (m, 30H; Ph),
4.31 (br m, 4H; CH), 1.63 (d, 3J=6.8 Hz, 12H; CH3), 0.77 ppm (s, 18H;
SiCH3); 13C{1H} NMR (75 MHz, C6D6): d=179.8 (NCN), 148.7 (i-Ph),
134.7 (i-Ph), 128.2 (Ph), 127.8 (Ph), 127.5 (Ph), 127.1 (Ph), 126.8 (Ph),
126.8 (Ph), 126.1 (Ph), 125.8 (Ph), 58.1 (CH), 26.8 (CH3), 5.2 ppm
(SiCH3); 29Si{1H} NMR (C6D6, 60 MHz): d=À10.1 ppm; MS (EI, 70 eV):
ACHTUNGTRENNUNG[{(PEBA)2ErCl}2] (5): This complex was prepared from ErCl3 (149 mg,
m/z
(%):
888
(5)
[MÀMe]+,
743 (74)
[MÀ{N
ACHTUNGTRENNUNG(SiMe3)2}]
0.55 mmol) and rac-KPEBA and crystallized from toluene/n-pentane.
Yield: 47 mg (0.06 mmol, 10%) as orange crystals; IR (ATR): n˜ =3056
(w), 3026 (w), 2974 (w), 2920 (w), 2875 (w), 1632 (m), 1576 (w), 1486
(m), 1447 (m), 1355 (w), 1303 (w), 1266 (w), 1208 (w), 1138 (w), 1072
(w), 1021 (w), 923 (w), 761 (m), 698 (s), 572 (w), 542 cmÀ1 (m); elemental
analysis calcd (%) for C46H46N4ClEr·C7H8: C 67.03, H 5.73, N 5.90;
found: C 67.20, H 5.91, N 5.83.
, 637 (4) [MÀ{N
ACHTUNGTRENNUNG
PhEt]
, 576 (31) [MÀPEBA]+, 534 (9), 493 (18), 415 (7), 328 (85) [PEBA]+, 313
(15) [PEBAÀMe]+, 294 (8), 223 (90) [PEBAÀPhEt]+, 209 (22) [PE-
BAÀPhEtÀMe]+, 180 (33), 146 (97) [{N
(SiMe3)2}]+, 120 (100) [PhEtN)+,
ACHTUNGTRENNUNG
105 (97) [PhEt]+, 77 (63) [Ph]+, 42 (16) [C2H4N]+; IR (ATR): n˜ =3406
(m), 3080 (w), 3059 (w), 3028 (w), 2974 (m), 2955 (m), 2919 (w), 2877
(w), 1636 (s), 1598 (w), 1577 (w), 1559 (w), 1541 (w), 1482 (m), 1450 (m),
1418 (w), 1360 (w), 1347 (w), 1325 (w), 1309 (m), 1267 (w), 1245 (w),
1213 (w), 1180 (w), 1142 (w), 1089 (w), 1072 (m), 1028 (w), 1008 (w), 984
(m), 928 (w), 871 (w), 826 (m), 758 (s), 698 (vs), 666 (m), 602 (m), 572
(m), 544 (s), 466 (w), 419 cmÀ1 (w); elemental analysis calcd (%) for
C52H64N5Si2Y: C 69.07, H 7.13, N 7.75; found: C 69.26, H 7.24, N 7.44.
[({(S)-PEBA}2YbCl)2] (6): This complex was prepared from YbCl3
(152 mg, 0.55 mmol) and (S)-KPEBA and crystallized from hot toluene.
Yield: 115 mg (0.13 mmol, 24%) as orange crystals; IR (ATR): n˜ =3057
(w), 3025 (w), 2959 (w), 2923 (w), 2871 (w), 1633 (m), 1486 (m), 1445
(m), 1353 (w), 1303 (w), 1269 (w), 1209 (w), 1138 (w), 1072 (w), 1021
(w), 912 (w), 761 (m), 697 (s), 572, 541 cmÀ1 (m); MS (EI, 70 eV): m/z
(%): 863 (4) [M]+, 848 (20) [MÀMe]+, 827 (66) [MÀCl]+, 710 (9), 537
(44), 501 (16), 417 (10), 387 (51), 328 (89) [PEBA]+, 223 (94) [PEBAÀ
PhEt]+, 180 (51), 120 (100) [PhEtN]+, 105 (95) [PhEt]+, 91 (45) [Bz]+, 77
(82) [Ph]+, 51 (18), 42 (30) [C2H4N]+, 27 (9) [CHN]+; elemental analysis
calcd (%) for C46H46N4ClYb·C7H8: C 66.62, H 5.70, N 5.86; found:
C 66.98, H 5.56, N 5.29.
[({(S)-PEBA}2LuCl)2] (7):[15b] This complex was prepared from LuCl3
(154 mg, 0.55 mmol) and (S)-KPEBA and crystallized from toluene/n-
pentane. Yield: 115 mg (0.13 mmol, 31%) as yellow crystals; 1H NMR
(300 MHz, [D8]THF, 238C): d=7.47–6.77 (m, 30H; Ph), 4.15 (q, 3J=
6.6 Hz, 4H; CH), 1.44 ppm (d, 3J=6.6 Hz, 12H; CH3); 13C{1H} NMR
(75 MHz, [D8]THF, 238C): d=180.3 (NCN), 149.3 (i-Ph), 136.1 (i-Ph),
129.0 (Ph), 128.9 (Ph), 128.8 (Ph), 127.9 (Ph), 126.7 (Ph), 126.2 (Ph), 58.3
(CH), 21.7 ppm (CH3); IR (ATR): n˜ =3058 (w), 3023 (w), 2963 (m), 2923
(w), 1629 (w), 1488 (w), 1447 (w), 1406 (m), 1366 (m), 1299 (m), 1184
(m), 1154 (w), 1067 (w), 1021 (w), 970 (w), 908 (w), 750 (m), 696 (s), 696
(w), 616 (w), 588 (w), 532 cmÀ1 (w); MS (EI, 70 eV): m/z (%): 864 (1)
[M]+, 849 (13) [MÀMe]+, 829 (57) [MÀCl]+, 759 (16), 703 (9) 537 (9),
501 (7), 417 (6), 328 (68) [PEBA]+, 223 (56) [PEBAÀPhEt]+, 180 (18),
120 (100) [PhEtN]+, 105 (100) [PhEt]+, 91 (17) [Bz]+, 77 (42) [Ph]+, 57
(12), 42 (13) [C2H4N]+, 27 (4) [CHN]+; elemental analysis calcd (%) for
C46H46N4ClLu·0.5C7H8: C 65.23, H 5.53, N 6.15; found: C 65.10, H 5.57,
N 5.63.
[{(S)-PEBA}2Lu{N
condensed onto a mixture of [Lu{NAHCNUTGTRENNUNG
ACHTUNGTRENNUNG
(S)-HPEBA (573 mg, 1.74 mmol) and the reaction mixture was stirred
overnight at 1008C. After cooling to room temperature, the volatile com-
pounds were removed under vacuum. After washing with n-pentane
(10 mL), colorless crystals were obtained from a hot solution in n-hep-
tane. Yield: 708 mg (0.72 mmol, 82%).
Pathway B. THF (10 mL) was condensed onto a mixture of compound 1
(197 mg, 0.24 mmol) and KNACHTNUTRGNEUNG(SiMe3)2 (45 mg, 0.24 mmol) and the reac-
tion mixture was stirred overnight at room temperature. The colorless
precipitate was filtered off and the solvent was removed under vacuum.
After washing with of n-pentane (10 mL), colorless crystals were ob-
tained from a hot solution in n-heptane. Yield: 46 mg (0.05 mmol, 20%);
1H NMR (300 MHz, C6D6, 258C): d=7.28–6.82 (m, 30H; Ph), 4.29 (br m,
4H; CH), 1.53 (d, 3J=6.8 Hz, 12H; CH3), 0.66 ppm (s, 18H; SiCH3);
13C{1H} NMR (75 MHz, C6D6, 258C): d=179.4 (NCN), 148.6 (i-Ph),
134.9 (i-Ph), 127.9 (Ph), 127.1 (Ph), 126.9 (Ph), 126.4 (Ph), 126.2 (Ph),
126.0 (Ph), 57.6 (CH), 27.1 (CH3), 5.5 ppm (SiCH3); 29Si{1H} NMR
(60 MHz, C6D6, 258C): d=À9.3 ppm; MS (EI, 70 eV): m/z (%): 989 (1)
[M]+, 974 (34) [MÀMe]+, 854 (11), 828 (16) [MÀ{N
(SiMe3)2}]+, 723 (21)
ACHTUNGTRENNUNG
[MÀ{N
ACHTUNGTRENNUNG
(23), 328 (87) [PEBA]+, 223 (68) [PEBAÀPhEt]+, 180 (77), 146 (98)
[NACTHNUTRGNEUNG
(SiMe3)2]+, 120 (96) [PhEtN]+, 105 (100) [PhEt]+, 91 (74) [Bz]+, 77
[{(S)-PEBA}3Sm] (8): THF (10 mL) was condensed at À1968C onto a
(90) [Ph]+, 42 (100) [C2H4N]+; IR (ATR): n˜ =3057 (w), 3023 (w), 2973
(w), 2954 (w), 2919 (w), 2919 (w), 2877 (w), 2857 (w), 1636 (m), 1598
(w), 1578 (w), 1483 (m), 1448 (m), 1360 (w), 1306 (w), 1266 (w), 1212
(w), 1142 (w), 1072 (w), 1027 (w), 1006 (w), 969 (w), 929 (w), 829 (w),
762 (m), 698 (s), 601 (w), 572 (w), 544 cmÀ1 (m); elemental analysis calcd
(%) for C52H64N5Si2Lu·1.5C7H8: C 66.52, H 6.79, N 6.21; found: C 66.61,
H 6.46, N 6.25.
mixture of [Sm{NACHTUNGTRENNUNG(SiHMe2)2}3ACHUTNGTREN(NGUN thf)2] (200 mg, 0.37 mmol) and (S)-HPEBA
(360 mg, 1.10 mmol). The reaction mixture was stirred overnight at room
temperature and the solvent was removed in vacuo. The residue was
washed with n-pentane and the product was crystallized from hot THF.
Yield: 200 mg (0.18 mmol, 48%) as yellow crystals; 1H NMR (300 MHz,
[D8]THF, 238C): d=8.97 (d, 3J=7.1 Hz, 6H; Ph), 8.30 (br s, 9H; Ph),
3
3
8.01 (t, J=7.4 Hz, 6H; Ph), 7.87 (t, J=7.4 Hz, 3H), 7.49 (br s, 9H; Ph),
7.42–6.88 (m, 12H; Ph), 3.33 (br s, 6H; CH), À2.66 ppm (br s, 18H;
CH3); 13C{1H} NMR (75 MHz, [D8]THF, 238C): d=148.4 (i-Ph), 139.9 (i-
Ph), 128.9 (Ph), 128.4 (Ph), 128.4 (Ph), 128.1 (Ph), 127.4 (Ph), 125.8 (Ph),
55.4 ppm (CH); IR (ATR): n˜ =3058 (w), 3025 (w), 2956 (w), 2921 (w),
2876 (w), 1635 (m), 1599 (w), 1485 (m), 1447 (m), 1352 (w), 1303 (w),
1265 (w), 1210 (w), 1140 (w), 1070 (w), 1025 (w), 908 (w), 797 (w), 763
(m), 699 (s), 599 (w), 572 (w), 542 cmÀ1 (m); MS (EI, 70 eV): m/z (%):
1134 (1) [M]+, 806 (67) [MÀPEBA]+, 702 (9), 479 (23), 328 (89)
[PEBA]+, 223 (72) [PEBAÀPhEt]+, 120 (100) [PhEtN]+, 105 (98)
[PhEt]+, 91 (82) [Bz]+, 77 (76) [Ph]+, 41 (19) [C2H3N]+, 27 (7) [CHN]+;
elemental analysis calcd (%) for C69H69N6Sm·C4H8O: C 72.77, H 6.44,
N 6.98; found: C 72.42, H 6.46, N 6.72.
Hydroamination reactions: The catalyst was weighed into a NMR tube
under an argon atmosphere. C6D6 (about 0.5 mL) was condensed into the
NMR tube and the mixture was frozen at À1968C. The reactant was in-
jected onto the solid mixture and the whole sample was melted and
mixed just before insertion into the core of the NMR machine (t0). The
ratio between the reactant and the product was calculated by comparison
of the integrations of the corresponding signals. Ferrocene was used as an
internal standard for the kinetic measurements. The substrates 2,2-di-
phenyl-pent-4-enylamine (11a),[28m] C-(1-allyl-cyclohexyl)-methylamine
(12a),[28m] 2,2-dimethylpent-4-en-1-amine (13a),[28m] 2,2-dimethylhex-5-en-
1-amine (14a),[28l] 5-phenylpent-4-yn-1-amine (15a),[37] and [1-(pent-2-
ynyl)-cyclohexyl]methanamine (16a)[31] were synthesized according to lit-
erature procedures. The 1H NMR data of 2-methyl-4,4-diphenylpyrroli-
&
8
&
www.chemeurj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Benzamidinates in Rare-Earth-Metal Coordination Chemistry
FULL PAPER
dine (11b),[28m] 3-methyl-2-aza-spiro-[4.5]decane (12b),[28m] 2,4,4-trime-
thylpyrrolidine (13b),[28m] 2,5,5-trimethylpiperidine (14b),[37] 2-benzyl-1-
Crystal data for compound 5: “2(C92H92Cl2Er2N8)·C5H12”; Mw =3502.46;
triclinic; a=14.149(3), b=16.590(3), c=19.387(4) ꢂ; a=86.88(3), b=
3
ACTHNUTRGNEUNG
pyrroline (15b),[36] and 3-propyl-2-azaspiro[4.5]dec-2-ene (16b)[31] con-
¯
84.03(3), g=71.25(3)8; V=4284.8(15) ꢂ ; T=200(2) K; space group P1;
Z=1; total reflns 119819; unique reflns 23140 (Rint =0.1724); final R1
values were 0.0689 (I>2s(I)); final wR(F2) values were 0.1287 (all data);
GOF on F2 was 1.104; Flack parameter=0.008(11).
formed with literature data.
General procedure for the preparation of Mosher amides: The cyclic
amine (0.1–0.2 mmol) was dissolved in dry CDCl3 (0.5 mL) in an NMR
tube. Then, Et3N (2 equiv) and (S)-(+)-a-methoxy-a-trifluoromethylphe-
nylacetic acid chloride (2–5 equiv) were added. Afterwards, the enantio-
meric excess was determined by 19F NMR spectroscopy at 60–708C.[28l]
Mosher adduct of: 11b: 19F NMR (CDCl3, 708C): d=À69.3 (major
isomer), À70.4 ppm (minor isomer); 12b: 19F NMR (CDCl3, 708C): d=
À69.7 (major isomer), À70.6 ppm (minor isomer); 13b: 19F NMR
(CDCl3, 608C): d=À69.7 (major isomer), À70.6 ppm (minor isomer);
The 19F NMR spectra are provided in the Supporting Information.
The 19F NMR spectrum of the Mosher adduct of compound 14b showed
an indefinable mixture of products and the enantiomeric excess of com-
pound 14b was determined by chiral HPLC analysis of the corresponding
1-naphthoyl amide.
Crystal data for compound 6: C92H92Cl2N8Yb2; Mw =1726.72; cubic; a=
24.596(3) ꢂ; V=14880(3) ꢂ3; T=200(2) K; space group I23; Z=6; total
reflns 10393; unique reflns 4574 (Rint =0.0419); final R1 values were
0.0263 (I>2s(I)); final wR(F2) values were 0.0676 (all data); GOF on F2
was 1.049; Flack parameter=À0.006(9).
Crystal data for compound 8: C69H69N6Sm; Mw =1132.65; cubic; a=
18.5719(6) ꢂ; V=6405.7(4) ꢂ3; T=200(2) K; space group P213; Z=4;
total reflns 33649; unique reflns 3873 (Rint =0.0641); final R1 values were
0.0349 (I>2s(I)); final wR(F2) values were 0.0868 (all data); GOF on F2
was 1.035; Flack parameter=À0.021(6).
Crystal data for compound 9: C52H64N5Si2Y; Mw =904.17; orthorhombic;
a=10.148(2), b=10.675(2), c=45.563(9) ꢂ; V=4935.7(17) ꢂ3; T=
150(2) K; space group P212121; Z=4; total reflns 39095; unique reflns
8243 (Rint =0.1222); final R1 values were 0.0455 (I>2s(I)); final wR(F2)
values were 0.0893 (all data); GOF on F2 was 0.912; Flack parameter=
À0.021(6).
CCDC-884826 (1), CCDC-884827 (2), CCDC-884828 (3), CCDC-884829
(4), CCDC-884830 (5), CCDC-884831 (8), and CCDC-884832 (9) contain
the supplementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Determination of enantiomeric excess by chiral HPLC analysis: The hy-
droamination products were derivatized as 1-naphthoyl amides by treat-
ing with 1-naphthoyl chloride (1 equiv) and Et3N (3 equiv) in CH2Cl2.[28h]
The ee values of the products were determined by HPLC analysis on a
chiral stationary phase (Regis (R,R)-b-Gem1 column, i.d.: 4.6 mm,
length: 250 mm, particle size: 5 mm). The HPLC conditions and ee
values are shown in Table 1.
X-ray crystallographic studies of compounds 1–10: Suitable crystals of
compounds 1–10 were covered in mineral oil (Aldrich) and mounted
onto a glass fiber. The crystals were transferred directly into the cold
stream of a Stoe IPDS 2 or Stoe IPDS 2T diffractometer (À738C or
À1238C N2). Data were corrected for absorption effects by using indexed
faces of the crystals.[38]
Acknowledgements
All structures were solved by using the program SHELXS-97.[39] The re-
maining non-hydrogen atoms were located from successive difference
Fourier map calculations. The refinements were carried out by using full-
matrix least-squares techniques on F2, by minimizing the function
J.K. thanks the Landesgraduiertenfçrderung for support.
2
2
(FoÀFc)2, where the weight was defined as 4F0 /2
ACHTNUGTNER(UNGN Fo ) and Fo and Fc were
[1] a) A. A. Trifonov, Coord. Chem. Rev. 2010, 254, 1327–1347; b) F. T.
Edelmann, F. H. Anthony, J. F. Mark in Chapter 3 Advances in the
Coordination Chemistry of Amidinate and Guanidinate Ligands, Vol.
57 Academic Press, 2008, pp. 183–352; c) P. C. Junk, M. L. Cole,
Chem. Commun. 2007, 1579–1590.
[2] a) M. Wedler, F. Knçsel, U. Pieper, D. Stalke, F. T. Edelmann, H.-D.
Amberger, Chem. Ber. 1992, 125, 2171–2181; b) F. T. Edelmann,
Chem. Soc. Rev. 2009, 38, 2253–2268.
the observed- and calculated structure factor amplitudes, respectively, by
using the program SHELXL-97.[39] The hydrogen atom contributions of
all of the compounds were calculated, but not refined. In each case, the
locations of the largest peaks in the final difference Fourier map calcula-
tions, as well as the magnitude of the residual electron densities, were of
no chemical significance. The structures of compound 7 and 10 have been
reported previously.[15b]
Crystal data for compound 1: C35H47Cl2N2O3Sm; Mw =765.00; monoclin-
ic; a=13.440(3), b=11.421(2), c=24.267(8) ꢂ; b=108.69(3)8; V=
3528.5(17) ꢂ3; T=200(2) K; space group P21/c; Z=4; total reflns
105130; unique reflns 7465 (Rint =0.0573); final R1 values were 0.0270
(I>2s(I)); final wR(F2) values were 0.0696 (all data); GOF on F2 was
1.088; Flack parameter=À0.025(11).
Crystal data for compound 2: C31H39Cl2N2O2Yb; Mw =715.58; monoclin-
ic; a=13.242(3), b=12.530(3), c=10.896(2) ꢂ; b=118.64(3)8; V=
1586.7(8) ꢂ3; T=200(2) K; space group C2; Z=2; total reflns 27046;
unique reflns 4253 (Rint =0.1049); final R1 values were 0.0281 ((I>2s(I));
final wR(F2) values were 0.0723 (all data); GOF on F2 was 1.045; Flack
parameter=À0.025(11).
Crystal data for compound 3: C31H39Cl2LuN2O2; Mw =717.51; monoclinic;
a=13.1521(11), b=12.4744(11), c=10.8067(9) ꢂ; b=118.413(6)8; V=
1559.4(2) ꢂ3; T=150(2) K; space group C2; Z=2; total reflns 6017;
unique reflns 3278 (Rint =0.0330); final R1 values were 0.0193 (I>2s(I));
final wR(F2) values were 0.0488 (all data); GOF on F2 was 1.039; Flack
parameter=À0.014(8).
Crystal data for compound 4: C92H92Cl2N8Sm2; Mw =1681.34; cubic; a=
24.754(3) ꢂ; V=15169(3) ꢂ3; T=150(2) K; space group I23; Z=6; total
reflns 66110; unique reflns 6068 (Rint =0.0567); final R1 values were
0.0352 (I>2s(I)); final wR(F2) values were 0.1069 (all data); GOF on F2
was 1.229; Flack parameter=0.020(16).
[3] a) F. T. Edelmann, Top. Curr. Chem. 1996, 179, 113–148; b) F. T.
Edelmann, Struct. Bonding (Berlin) 2010, 137, 109–164; c) F. T.
Edelmann, Angew. Chem. 1995, 107, 2647–2669; Angew. Chem. Int.
Ed. Engl. 1995, 34, 2466–2488.
[4] a) F. T. Edelmann, J. Alloys Compd. 1994, 207–208, 182–188;
b) J. R. Hagadorn, J. Arnold, Organometallics 1996, 15, 984–991.
[5] S. Bambirra, D. van Leusen, A. Meetsma, B. Hessen, J. H. Teuben,
Chem. Commun. 2003, 522–523.
[6] a) L. Zhang, M. Nishiura, M. Yuki, Y. Luo, Z. Hou, Angew. Chem.
2008, 120, 2682–2685; b) V. Y. Rad’kov, G. G. Skvortsov, D. M.
Lyubov, A. V. Cherkasov, G. K. Fukin, A. S. Shavyrin, D. Cui, A. A.
Trifonov, Eur. J. Inorg. Chem. 2012, 2289–2297; c) S. Bambirra,
M. W. Bouwkamp, A. Meetsma, B. Hessen, J. Am. Chem. Soc. 2004,
126, 9182–9183.
[7] E. A. Bijpost, R. Duchateau, J. H. Teuben, J. Mol. Catal. A 1995, 95,
121–128.
[8] S. Ge, A. Meetsma, B. Hessen, Organometallics 2008, 27, 3131–
3135.
[9] S. Bambirra, H. Tsurugi, D. van Leusen, B. Hessen, Dalton Trans.
2006, 1157–1161.
[10] a) Y. Luo, Y. Yao, Q. Shen, J. Sun, L. Weng, J. Organomet. Chem.
2002, 662, 144–149; b) A. A. Trifonov in Rare-Earth Metal Com-
plexes Supported by Nitrogen-Containing Ligands in Olefin Polymer-
ization Olefin Upgrading Catalysis by Nitrogen-based Metal Com-
Chem. Eur. J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
9
&
ÞÞ
These are not the final page numbers!

P. W. Roesky et al.
plexes I, Vol. 35 (Eds.: J. Campora, G. Giambastiani), Springer,
Netherlands, 2011, pp. 119–152.
[11] a) C. Averbuj, E. Tish, M. S. Eisen, J. Am. Chem. Soc. 1998, 120,
8640–8646; b) J. Li, S. Huang, L. Weng, D. Liu, J. Organomet.
Chem. 2006, 691, 3003–3010; c) L. A. Koterwas, J. C. Fettinger,
L. R. Sita, Organometallics 1999, 18, 4183–4190.
gini, A. Fasana, M. Rigamonti, J. Organomet. Chem. 2011, 696, 277–
295; aa) D. Crozet, M. Urrutigoꢃty, P. Kalck, ChemCatChem 2011, 3,
1102–1118; ab) G.-F. Zi, J. Organomet. Chem. 2011, 696, 68–75;
ac) J. Jenter, A. Lꢀhl, P. W. Roesky, S. Blechert, J. Organomet.
Chem. 2011, 696, 406–418; ad) X.-Y. Liu, Z. Guo, S. S. Dong, X.-H.
Li, C.-M. Che, Chem. Eur. J. 2011, 17, 12932–12945.
[12] H. Brunner, J. Lukassek, G. Agrifoglio, J. Organomet. Chem. 1980,
195, 63–76.
[13] E. Nelkenbaum, M. Kapon, M. S. Eisen, J. Organomet. Chem. 2005,
690, 3154–3164.
[14] a) A. Bertogg, A. Togni, Organometallics 2006, 25, 622–630; b) H.
Brunner, G. Agrifoglio, Monatsh. Chem. 1980, 111, 275–287.
[15] a) P. Benndorf, C. Preuß, P. W. Roesky, J. Organomet. Chem. 2011,
696, 1150–1155; b) P. Benndorf, J. Jenter, L. Zielke, P. W. Roesky,
Chem. Commun. 2011, 47, 2574–2576.
[16] P. Benndorf, Dissertation, Karlsruher Institut fꢀr Technologie (KIT),
Karlsruhe, 2010.
[17] R. Shannon, Acta Crystallographica Section A 1976, 32, 751–767.
[18] A. Trifonov, G. Skvortsov, D. Lyubov, G. Fukin, E. Fedorova, M.
Bochkarev, Russ. Chem. Bull. 2005, 54, 2511–2518.
[19] F. A. Cotton, G. Wilkinson, Advanced Inorganic Chemistry, Wiley-
Interscience, New York, 1988, p. 54.
[20] A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7–13.
[21] J. Richter, J. Feiling, H.-G. Schmidt, M. Noltemeyer, W. Brꢀser, F. T.
Edelmann, Z. Anorg. Allgem. Chem. 2004, 630, 1269–1275.
[22] S. Hong, T. J. Marks, Acc. Chem. Res. 2004, 37, 673–686.
[23] a) J. A. R. Schmidt, J. Arnold, Chem. Commun. 1999, 2149–2150;
b) Y. Luo, P. Xu, Y. Lei, Y. Zhang, Y. Wang, Inorg. Chim. Acta
2010, 363, 3597–3601.
[24] W. Scherer, D. J. Wolstenholme, V. Herz, G. Eickerling, A. Brꢀck, P.
Benndorf, P. W. Roesky, Angew. Chem. 2010, 122, 2291–2295;
Angew. Chem. Int. Ed. 2010, 49, 2242–2246.
[27] a) M. A. Giardello, V. P. Conticello, L. Brard, M. R. Gagne, T. J.
Marks, J. Am. Chem. Soc. 1994, 116, 10241–10254; b) M. R. Gagne,
L. Brard, V. P. Conticello, M. A. Giardello, C. L. Stern, T. J. Marks,
Organometallics 1992, 11, 2003–2005; c) S. Hong, A. M. Kawaoka,
T. J. Marks, J. Am. Chem. Soc. 2003, 125, 15878–15892.
[28] a) I. Aillaud, C. Olier, Y. Chapurina, J. Collin, E. Schulz, R. g. Guil-
lot, J. r. m. Hannedouche, A. Trifonov, Organometallics 2011, 30,
3378–3385; b) J. Collin, J.-C. Daran, E. Schulz, A. Trifonov, Chem.
Commun. 2003, 3048–3049; c) D. V. Gribkov, K. C. Hultzsch, F.
Hampel, Chem. Eur. J. 2003, 9, 4796–4810; d) P. N. O’Shaughnessy,
P. D. Knight, C. Morton, K. M. Gillespie, P. Scott, Chem. Commun.
2003, 1770–1771; e) P. N. O’Shaughnessy, P. Scott, Tetrahedron:
Asymmetry 2003, 14, 1979–1983; f) Y. K. Kim, T. Livinghouse, Y.
Horino, J. Am. Chem. Soc. 2003, 125, 9560–9561; g) D. V. Gribkov,
K. C. Hultzsch, Chem. Commun. 2004, 730–731; h) S. Hong, S. Tian,
M. V. Metz, T. J. Marks, J. Am. Chem. Soc. 2003, 125, 14768–14783;
i) I. Aillaud, D. Lyubov, J. Collin, R. Guillot, J. Hannedouche, E.
Schulz, A. Trifonov, Organometallics 2008, 27, 5929–5936; j) I. Ail-
laud, J. Collin, C. Duhayon, R. Guillot, D. Lyubov, E. Schulz, A. Tri-
fonov, Chem. Eur. J. 2008, 14, 2189–2200; k) J. Y. Kim, T. Living-
house, Org. Lett. 2005, 7, 1737–1739; l) D. V. Gribkov, K. C.
Hultzsch, F. Hampel, J. Am. Chem. Soc. 2006, 128, 3748–3759;
m) P. H. Martinez, K. C. Hultzsch, F. Hampel, Chem. Commun.
2006, 2221–2223; n) A. L. Reznichenko, H. N. Nguyen, K. C.
Hultzsch, Angew. Chem. 2010, 122, 9168–9171; Angew. Chem. Int.
Ed. 2010, 49, 8984–8987; o) N. Meyer, A. Zulys, P. W. Roesky, Orga-
nometallics 2006, 25, 4179–4182.
[25] K. H. Den Haan, J. L. De Boer, J. H. Teuben, A. L. Spek, B. Kojic-
Prodic, G. R. Hays, R. Huis, Organometallics 1986, 5, 1726–1733.
[26] a) J. Seayad, A. Tillack, C. G. Hartung, M. Beller, Adv. Synth. Catal.
2002, 344, 795–813; b) I. Bytschkov, S. Doye, Eur. J. Org. Chem.
2003, 935–946; c) F. Pohlki, S. Doye, Chem. Soc. Rev. 2003, 32, 104–
114; d) P. W. Roesky, T. E. Mꢀller, Angew. Chem. 2003, 115, 2812–
2814; Angew. Chem. Int. Ed. 2003, 42, 2708–2710; e) F. Alonso, I. P.
Beletskaya, M. Yus, Chem. Rev. 2004, 104, 3079–3160; f) J. F. Hart-
wig, Pure Appl. Chem. 2004, 76, 507–516; g) K. C. Hultzsch, Adv.
Synth. Catal. 2005, 347, 367–391; h) K. C. Hultzsch, Org. Biomol.
Chem. 2005, 3, 1819–1824; i) R. A. Widenhoefer, X. Han, Eur. J.
Org. Chem. 2006, 4555–4563; j) I. Aillaud, J. Collin, J. Hannedou-
che, E. Schulz, Dalton Trans. 2007, 5105–5118; k) J.-J. Brunet, N.-C.
Chu, M. Rodriguez-Zubiri, Eur. J. Inorg. Chem. 2007, 4711–4722;
l) P. A. Hunt, Dalton Trans. 2007, 1743–1754; m) A. V. Lee, L. L.
Schafer, Eur. J. Inorg. Chem. 2007, 2245–2255; n) R. Severin, S.
Doye, Chem. Soc. Rev. 2007, 36, 1407–1420; o) E. Smolensky, M. S.
Eisen, Dalton Trans. 2007, 5623–5650; p) T. Andrea, M. S. Eisen,
Chem. Soc. Rev. 2008, 37, 550–567; q) T. E. Mꢀller, K. C. Hultzsch,
M. Yus, F. Foubelo, M. Tada, Chem. Rev. 2008, 108, 3795–3892;
r) R. Dorta in Iridium-Catalyzed Hydroamination, Wiley-VCH,
Weinheim, 2009, pp. 145–172; s) P. W. Roesky, Angew. Chem. 2009,
121, 4988–4991; Angew. Chem. Int. Ed. 2009, 48, 4892–4894; t) G.
Zi, Dalton Trans. 2009, 9101–9109; u) K. D. Hesp, M. Stradiotto,
ChemCatChem 2010, 2, 1192–1207; v) T. Li, J. Jenter, P. W. Roesky,
Struct. Bonding (Berlin) 2010, 137, 165–228; w) A. L. Reznichenko,
K. C. Hultzsch in Asymmetric Hydroamination, Wiley-VCH, Wein-
heim, 2010, pp. 341–375; x) J. G. Taylor, L. A. Adrio, K. K. Hii,
Dalton Trans. 2010, 39, 1171–1175; y) B. Alcaide, P. Almendros,
Adv. Synth. Catal. 2011, 353, 2561–2576; z) E. M. Beccalli, G. Brog-
[29] a) A. L. Gott, A. J. Clarke, G. J. Clarkson, P. Scott, Organometallics
2007, 26, 1729–1737; b) M. C. Wood, D. C. Leitch, C. S. Yeung, J. A.
Kozak, L. L. Schafer, Angew. Chem. 2006, 119, 358–362; Angew.
Chem. Int. Ed. 2006, 46, 354–358; c) T. Ogata, A. Ujihara, S. Tsuchi-
da, T. Shimizu, A. Kaneshige, K. Tomioka, Tetrahedron Lett. 2007,
48, 6648–6650; d) X. Shen, S. L. Buchwald, Angew. Chem. 2010,
122, 574–577; Angew. Chem. Int. Ed. 2010, 49, 564–567; e) K.
Manna, S. Xu, A. D. Sadow, Angew. Chem. 2011, 123, 1905–1908;
Angew. Chem. Int. Ed. 2011, 50, 1865–1868; f) X. Zhang, T. J.
Emge, K. C. Hultzsch, Angew. Chem. Int. Ed. 2012, 51, 394–398.
[30] M. R. Gagne, C. L. Stern, T. J. Marks, J. Am. Chem. Soc. 1992, 114,
275–294.
[31] M. Rastꢄtter, A. Zulys, P. W. Roesky, Chem. Eur. J. 2007, 13, 3606–
3616.
[32] M. E. Jung, G. Piizzi, Chem. Rev. 2005, 105, 1735–1766.
[33] M. D. Taylor, C. P. Carter, J. Inorg. Nucl. Chem. 1962, 24, 387–391.
[34] R. Anwander, O. Runte, J. Eppinger, G. Gerstberger, E. Herdtweck,
M. Spiegler, J. Chem. Soc. Dalton Trans. 1998, 847–858.
[35] D. C. Bradley, J. S. Ghotra, F. A. Hart, J. Chem. Soc. Dalton Trans.
1973, 1021–1023.
[36] Y. Li, T. J. Marks, J. Am. Chem. Soc. 1996, 118, 9295–9306.
[37] M. R. Crimmin, M. Arrowsmith, A. G. M. Barrett, I. J. Casely, M. S.
Hill, P. A. Procopiou, J. Am. Chem. Soc. 2009, 131, 9670–9685.
[38] Stoe&Cie in X-AREA and X-RED32, Darmstadt, Germany, 2006.
[39] G. M. Sheldrick, Acta Crystallogr. Sect. A 2008, 64, 112–122.
Received: July 10, 2012
Published online: && &&, 0000
&
10
&
www.chemeurj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Benzamidinates in Rare-Earth-Metal Coordination Chemistry
FULL PAPER
Lanthanide Complexes
P. Benndorf, J. Kratsch, L. Hartenstein,
C. M. Preuss, P. W. Roesky* &&&& — &&&&
Chiral Benzamidinate Ligands in
Rare-Earth-Metal Coordination
Chemistry
Enantiomerically pure lanthanide com-
plexes were synthesized as the first
rare-earth-metal complexes containing
a chiral amidinate ligand. The catalytic
activities and enantioselectivities of
these complexes were studied in
hydroamination reactions.
Chem. Eur. J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
11
&
ÞÞ
These are not the final page numbers!