Synthesis and structural characterization of amido heteroscorpionate rare-earth metal complexes and hydroamination of aminoalkenes

Article abstract of DOI:10.1039/c5nj00930h

The synthesis, characterization and fluxional behaviour of novel heteroscorpionate rare-earth (including the group 3 metals, scandium and yttrium) complexes are reported. The reaction of acetamide and thioacetamide heteroscorpionate protio-ligands pbptamH

Full text of DOI:10.1039/c5nj00930h

NJC
View Article Online
View Journal | View Issue
PAPER
Synthesis and structural characterization of amido
heteroscorpionate rare-earth metal complexes
and hydroamination of aminoalkenes†
Cite this: New J. Chem., 2015,
39, 7672
Antonio Otero,*a Agustın Lara-Sanchez,*a Jose A. Castro-Osma,a
´
´
´
Isabel Marquez-Segovia,a Carlos Alonso-Moreno,b Juan Fernandez-Baeza,a
´
´
Luis F. Sanchez-Barbaa and Ana M. Rodrıguezc
´
´
The synthesis, characterization and fluxional behaviour of novel heteroscorpionate rare-earth (including
the group 3 metals, scandium and yttrium) complexes are reported. The reaction of acetamide and
thioacetamide heteroscorpionate protio-ligands pbptamH, tbptamH, pbpamH and (S)-mbpamH with
1 equivalent of tris(silylamide) precursors [M{N(SiHMe2)2}3(thf)n] (n = 1, M = Sc; n = 2, M = Y, Lu)
proceeded to give good yields of neutral heteroscorpionate disilylamide complexes [M{N(SiHMe2)2}2-
(k3-pbptam)(thf)n] (M = Sc, n = 0, 1; M = Y, n = 1, 2; M = Lu, n = 1, 3), [M{N(SiHMe2)2}2(k3-tbptam)(thf)n]
(M = Sc, n = 0, 4; M = Y, n = 1, 5; M = Lu, n = 1, 6), [M{N(SiHMe2)2}2(k3-pbpam)(thf)n] (M = Sc, n = 0, 7;
M = Y, n = 1, 8; M = Lu, n = 1, 9) and [M{N(SiHMe2)2}2{k3-(S)-mbpam}(thf)n] (M = Sc, n = 0, 10; M = Y,
n = 1, 11; M = Lu, n = 1, 12). Scandium complexes were isolated as THF-free compounds with a pseudo
five-coordinate environment, while yttrium and lutetium complexes were isolated with an octahedral
geometry due to the coordination of a THF molecule. The fluxionality of complexes 1–12 in solution
was investigated by VT NMR spectroscopy. The structures of these compounds were determined by
spectroscopic methods and the X-ray crystal structure of 1 was also established. Complexes 1–12 are
efficient catalysts for the intramolecular hydroamination of aminoalkenes, with TOF values up to 198 hꢀ1
obtained at 70 1C for 2,2-diphenyl-pent-4-enylamine (13) using complex 11 as a catalyst. Enantio-
selectivities of up to 99% ee were achieved with the cyclization of aminoalkene 13 using the single
enantiopure complex 12. The hydroamination reactions showed a zero-order rate dependence on
substrate concentration and first-order rate dependence on catalyst concentration.
Received (in Montpellier, France)
14th April 2015,
Accepted 23rd June 2015
DOI: 10.1039/c5nj00930h
www.rsc.org/njc
and murmuring strange revelations and possibilities’ was the
address to the British association in 1887 by Sir William
Introduction
These elements (rare-earths) perplex us in our researches, baffle Crookes to highlight the intriguing role that these elements
us in our speculations and haunt us in our dreams. They had in the field of chemistry. Since then, inorganic chemists
stretch like an unknown sea before us – mocking, mystifying have made room for an ever-growing list of new related com-
pounds of group 3 metals, lanthanides and actinides, and a huge
variety of structural arrangements, unique chemical properties,
a
´
´
Universidad de Castilla-La Mancha, Departamento de Quımica Inorganica,
and very specific applications have been reported.1 Nowadays,
the synthesis of new compounds of these elements is one of the
most attractive fields for potential applications in homogeneous
catalysis, organic synthesis and materials science.2 Despite this
situation, the use of these systems as homogeneous catalysts is
largely restricted to the laboratory and currently there are only
few examples in which they are used on an industrial scale.
Among the design of new rare-earth (including the group 3
metals scandium and yttrium) complexes for homogeneous
catalysis, the most widely investigated compounds are those
bearing Cp-type ligands, not only because they have interesting
chemical structures and unique reactivity but also due to their
´
´
´
´
Organica y Bioquımica-Centro de Innovacion en Quımica Avanzada (ORFEO-CINQA),
´
´
Facultad de Ciencias y Tecnologıas Quımicas, 13071-Ciudad Real, Spain.
E-mail: antonio.otero@uclm.es, agustin.lara@uclm.es
b
c
´
´
Universidad de Castilla-La Mancha, Departamento de Quımica Inorganica,
´
´
´
´
Organica y Bioquımica-Centro de Innovacion en Quımica Avanzada
(ORFEO-CINQA), Facultad de Farmacia, 02071-Albacete, Spain
´
´
Universidad de Castilla-La Mancha, Departamento de Quımica Inorganica,
´
´
´
´
Organica y Bioquımica-Centro de Innovacion en Quımica Avanzada
´
(ORFEO-CINQA), Escuela Tecnica Superior de Ingenieros Industriales,
13071 Ciudad Real, Spain
† Electronic supplementary information (ESI) available: Experimental details,
procedures for catalytic intramolecular hydroamination; kinetic measurements
and representative kinetic plots. CCDC 1059154. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/c5nj00930h
7672 | New J. Chem., 2015, 39, 7672--7681
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015

View Article Online
Paper
NJC
versatile catalytic activity and selectivity in the polymerization of
olefins or conjugated dienes.3 Recent years have witnessed
increased attention on organo-f-compounds based on N, O and
P heteroatoms for homogenous catalysis. This is due to the fact
that the strong metal–ligand bonds can stabilize high electro-
philicity and provide exceptional and tunable steric and electronic
features required.4,3d
Ancillary ligands with multiple coordinating sites and large
steric bulk are favoured to stabilize rare-earth metal complexes.
In this context, scorpionate compounds with multiple coordina-
tion sites have been exploited as ancillary ligands.5 Among them,
heteroscorpionates are some of the most versatile tridentate
ligands6 and they are able to coordinate and stabilize a wide
variety of f-block elements. In recent years, different groups have
contributed a great deal to the design of new heteroscorpionate
ligands related to the bis(pyrazol-1-yl)methane system with
several pendant donor arms such as carboxylate, dithiocarb-
oxylate, aryloxide, alkoxide, amide, cyclopentadienyl, acetamidate,
thioacetamidate and amidinate.7 We recently focused on extend-
ing the scope of the chemistry of organo-f-elements, including
scandium and yttrium, to the synthesis of heteroscorpionate
complexes. The synthetic accessibility, structural arrangements [pbptamH
Scheme 1 Synthesis of compounds 1–12.
=
N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacet-
and catalytic performance were studied. Since 2005, when we amide], tbptamH [tbptamH = N-tert-butyl-2,2-bis(3,5-dimethyl-
reported our first study related to scandium and yttrium pyrazol-1-yl)thioacetamide], pbpamH [pbpamH = N-phenyl-2,2-
compounds,8 our efforts have been focused on the synthesis bis(3,5-dimethylpyrazol-1-yl)acetamide] and (S)-mbpamH [(S)-
of new derivatives as potential initiators in the ring-opening mbpamH = (S)-(ꢀ)-N-a-methylbenzyl-2,2-bis(3,5-dimethylpyrazol-
polymerization of cyclic esters9 and in the hydroamination of 1-yl)acetamide] with 1 equivalent of tris(silylamide) complexes
different aminoalkenes.10
[M{N(SiHMe2)2}3(thf)n]12 (n = 1, M = Sc; n = 2, M = Y, Lu)
In this new contribution to the chemistry of the rare-earth (Scheme 1). The reactions were carried out in toluene and, after
elements, we describe in detail the synthesis and characteriza- an appropriate work-up, complexes 1–6 and 7–12 were isolated in
tion of a new series of achiral and chiral silylamide hetero- ca. 80% yield as yellow and white solids, respectively. The com-
scorpionate rare-earth compounds. The study of the different plexes were soluble in THF and toluene but insoluble in n-hexane.
structural arrangements in these new entities and their perfor- Scandium complexes were isolated as THF-free compounds, and
mance in the catalytic hydroamination of aminoalkenes were complexes 10–12 were isolated as single enantiopure compounds.
also explored.
Various acetamidate and thioacetamidate compounds were
characterized spectroscopically (see Experimental section). The
13C NMR signals of carbonyl and thiocarbonyl groups in these
complexes are good indicators of bonding mode of the acet-
amidate or thioacetamidate moieties of the ligands. Thio-
carbonyl and carbonyl carbon resonances, RNCE, are shifted
Results and discussion
Synthesis, structures, and fluxional behaviour
Acetamide or thioacetamide heteroscorpionate precursors con- to higher field with respect to those of neutral ligands9a,b,c,11
tain Lewis basic coordinating groups (N and O or S centres in (see the Experimental section), indicating that the acetamidate
the ‘arm’ of the heteroscorpionate moiety) and this makes them or thioacetamidate moieties are coordinated to the metal
an interesting type of ligand for the preparation of rare-earth centres through O or S atoms (see Scheme 1). However, a small
complexes due to their wide variety of coordination modes.9,11 amount of delocalized E–C–N double bond probably exists in
Thus, Sc, Y and Lu were the metals chosen to design new the acetamidate and thioacetamidate moieties of the hetero-
complexes that would have interesting features for hydroamina- scorpionate ligands.
tion catalysis. The new silylamide compounds [M{N(SiHMe2)2}2-
The 1H and 13C{1H} NMR spectra of 1–9 (without a chiral
(k3-pbptam)(thf)n] (M = Sc, 1, n = 0; M = Y 2, Lu 3, n = 1), carbon) at room temperature show a singlet for each of the H4,
[M{N(SiHMe2)2}2(k3-tbptam)(thf)n] (M = Sc 4, n = 0; M = Y 5, Lu 6, Me3 and Me5 pyrazole protons and carbons, indicating that the
n = 1), [M{N(SiHMe2)2}2(k3-pbpam)(thf)n] (M = Sc 7, n = 0; M = Y 8, pyrazoles are equivalent, along with one resonance for the two
Lu 9, n = 1) and [M{N(SiHMe2)2}2{k3-(S)-mbpam}(thf)n] (M = Sc silylamide ligands and two multiplets for the THF protons in
10, n = 0; M = Y 11, Lu 12, n = 1) were synthesized in a the yttrium and lutetium complexes. The 1H and 13C{1H} NMR
straightforward way by an amine elimination route, which spectra of 10–12 (bearing a stereogenic carbon atom) show two
involved the reaction of the previously reported acetamide and singlets for each of the H4, Me3 and Me5 pyrazole protons
thioacetamide heteroscorpionate protio-precursors9a,b,c pbptamH and carbons, two signals for the silylamide ligands and two
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem., 2015, 39, 7672--7681 | 7673

View Article Online
NJC
Paper
Fig. 1 1H NMR spectrum of [Lu{N(SiHMe2)2}2{k3-(S)-mbpam}(thf)] (10).
multiplets for THF protons in yttrium and lutetium complexes
(see Fig. 1). These results are consistent with a five coordinate
disposition for the scandium complexes and an octahedral
structural disposition for the yttrium and lutetium complexes.
Thus, these spectroscopic data indicate that the acetamidate or
thioacetamidate heteroscorpionate ligands are coordinated in a
facial, ‘tripodal’ fashion with a k3-NNE coordination mode.
1
Phase-sensitive H NOESY-1D experiments were carried out to
confirm the assignment of the signals for the Me3, Me5 and H4
groups of the pyrazole ring and the SiHMe2 group. The assign-
ment of 13C{1H} NMR signals was made on the basis of addi-
tional H–13C heteronuclear correlation experiments (g-HSQC).
1
Fig. 3 Variable-temperature 1H NMR spectra in the region of the methyl
groups of compound 1 in toluene-d8.
As mentioned above, the scandium compounds have a five-
coordinate disposition and in this arrangement, two isomers
are possible: one with a square planar pyramidal geometry
(Fig. 2a) and another with a trigonal bipyramidal geometry
(Fig. 2b). The pyrazole rings are equivalent in both isomers.
However, in the first isomer, the silylamide ligands are equivalent
but in the second they are different; a situation that is consistent
with a square planar pyramidal geometry (Fig. 2a). The room
temperature 1H NMR spectra of the scandium complexes
(1, 4 and 7; with achiral heteroscorpionate ligands) show broad
resonances for the two silylamide ligands, indicating the existence
of an exchange process between these ligands close to the
coalescence temperature. Therefore, the dynamic behaviour
of the scandium complexes was studied by VT NMR spectro-
scopy. In the case of complex 1, the VT NMR analysis showed
that the resonance of the silylamide protons broadens and
becomes resolved into a number of separate peaks at low
temperature. A stacked plot of the relevant sections of the
1
variable-temperature H NMR spectra of 1 is shown in Fig. 3.
At room temperature, the exchange of the silylamide groups
occurs and, accordingly, one set of signals is observed. When
the temperature was decreased to below 0 1C, two sets of signals
were observed for the silylamide ligands (Fig. 3).
A five-coordinate geometry is proposed for Sc compounds,
but for derivatives of Y and Lu, which have larger ionic radii, a
six-coordinate environment can be considered (Scheme 1). In
this arrangement, two isomers are possible, i.e., with the cis and
trans disposition of the THF ligand with respect to the oxygen
or sulphur atom of the RNCE moiety (Fig. 4). As mentioned
previously, the room temperature 1H NMR spectra of yttrium
and lutetium complexes that contain achiral heteroscorpionate
ligands show a singlet for each of the H4, Me3 and Me5 pyrazole
protons, indicating that the pyrazoles are equivalent. This
situation is consistent with the isomer in which the THF ligand
is trans to the RNCE moiety. However, dynamic behaviour was
observed involving the THF group and the silylamide ligands.
The VT NMR analysis showed that the resonances of the
silylamide and THF ligands that are directly bonded to the
metal centre, as well as those of the pyrazole rings, broaden
at ꢀ80 1C and become resolved into a number of separate peaks
for each of the ligands present (Fig. S1, ESI†). Thus, the two
Fig. 2 Proposed structures for the two isomers of scandium complexes.
7674 | New J. Chem., 2015, 39, 7672--7681
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015

View Article Online
Paper
NJC
Fig. 4 Proposed structures for the two isomers of yttrium and lutetium
complexes.
pyrazole rings will be not equivalent and this situation is
consistent with the isomer in which the THF ligand is cis to
the RNCE moiety (Fig. 4). It is worth noting that at low
temperature, and given the coordination mode of the ligands,
isomers with a cis disposition (Fig. 4) are chiral compounds.
Conclusive evidence was not found for the presence of
b-(SiH) agostic interactions in the compounds (1–12) in a
solution; a situation that is frequently observed in similar
complexes.13 The 1H NMR spectra show the SiH signals in
the range of 5.00–5.90 ppm, which is significantly downfield
compared to the same SiH resonances from precursor com-
plexes [M{N(SiHMe2)2}3(thf)n].12 The value of the 1JSiH coupling
constant is generally a good tool to gauge the intensity of metal
Fig. 5 ORTEP representation of the molecular structure of 1 (ellipsoids
drawn at 30% probability). H atoms are omitted for clarity except those that
take part in the agostic interactions.
Table 1 Crystal data and structure refinement details for 1
1
Molecular formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C26H48N7SScSi4
648.09
180(2)
0.71073
Monoclinic
C2/c
37.191(5)
10.591(4)
25.678(3)
133.52(1)
7334(3)
1
b-(Si–H) agostic interactions.12,13 The JSiH values found for
complexes 1–12 are in the range that is indicative of non-
agostic interactions (170–180 Hz) observed in rare-earth com-
plexes.12,13 Furthermore, it is well known that IR spectroscopy
is an efficient method to corroborate the presence of b-(Si–H)
intramolecular agostic interactions. The Si–H stretching frequen-
cies in the FTIR spectra of 1–12 for the solid state are in the region
between 1900 and 2200 cmꢀ1 with low-energy shoulders, and this
situation indicates the presence of weak agostic b-(Si–H) inter-
actions in the solid state.12,13
The molecular structure of complex 1 was determined by
X-ray diffraction and the ORTEP drawing is depicted in Fig. 5.
The crystallographic data and selected interatomic distances
and angles are given in Tables 1 and 2, respectively. The
molecular structure of 1 determined by X-ray diffraction is in
good agreement with the solution structures deduced from the
spectroscopic data. The heteroscorpionate ligand is attached to
the scandium atom through two nitrogen atoms of pyrazole
rings and the sulphur atom from the thioacetamidate moiety is
in a k3-NNS coordination mode with the expected fac coordina-
b (Å)
c (Å)
b (1)
Volume (Å3)
Z
8
Density (calculated) (g cmꢀ3
)
1.174
0.414
2768
0.43 ꢁ 0.34 ꢁ 0.22
ꢀ44 r h r 44
ꢀ12 r k r 11
ꢀ30 r l r 30
6244 [R(int) = 0.1955]
6244/142/426
0.871
Absorption coefficient (mmꢀ1
F(000)
)
Crystal size (mm3)
Index ranges
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I 4 2(s)I]
R1 = 0.0621
wR2 = 0.1071
0.277 and ꢀ0.245
Largest diff. peak and hole, e Åꢀ3
tion. In addition, the scandium centre is coordinated to two This distortion is manifested in the N(1)–Sc(1)–N(3), N(6)–Sc(1)–
disilylamide ligands. N(7), N(3)–Sc(1)–N(7) and N(1)–Sc(1)–N(6) angles of 84.8(2)1,
A quantitative measure (t value)14 has been described to 104.5(2)1, 131.4(2)1 and 94.2(1)1, respectively.
determine the extent of five-coordinate geometries. A value of
The distances between the Sc atom and the nitrogen atoms
zero identifies a compound as being perfectly square pyramidal of the pyrazole rings Sc(3)–N(1) and Sc(1)–N(3) [2.264(4) Å and
and a value of one as perfectly trigonal bipyramidal. The t value 2.269(4) Å] correlate well with the corresponding distances
assigned to complex 1 is 0.59 and this confirms a distorted found in other scandium pyrazolyl complexes.9d,e The bond
situation between the two five-coordination geometries, probably distances of Sc(1)–N(6) (2.095(4) Å) and Sc(1)–N(7) (2.041(5) Å)
due to the constraints imposed by the heteroscorpionate ligand. are similar to the corresponding distances found in other
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem., 2015, 39, 7672--7681 | 7675

View Article Online
NJC
Paper
Table 2 Selected bond lengths [Å] and angles [1] for 1
Table 3 Hydroamination/cyclization reaction of aminoalkenes 13–16
catalyzed by complexes 1–12
Bond lengths (Å)
Angles (1)
Sc(1)–N(1)
Sc(1)–N(3)
Sc(1)–N(6)
Sc(1)–N(7)
Sc(1)–S(1)
Sc(1)–Si(3)
Sc(1)–Si(4)
Sc(1)–Si(1)
Sc(1)–Si(2)
2.264(4)
2.269(4)
2.095(4)
2.041(5)
2.648(2)
3.086(3)
3.207(2)
3.312(2)
3.321(2)
N(6)–Sc(1)–N(7)
N(1)–Sc(1)–N(7)
N(1)–Sc(1)–N(6)
N(3)–Sc(1)–N(7)
N(3)–Sc(1)–N(6)
N(1)–Sc(1)–N(3)
N(7)–Sc(1)–S(1)
N(6)–Sc(1)–S(1)
Si(1)–N(6)–Si(2)
Si(1)–N(6)–Sc(1)
Si(2)–N(6)–Sc(1)
Si(4)–N(7)–Si(3)
Si(3)–N(7)–Sc(1)
104.5(2)
136.1(2)
94.2(1)
131.4(2)
94.6(2)
84.9(2)
84.1(1)
171.4(1)
118.2(9)
121.0(2)
120.3(9)
129.2(3)
110.9(3)
scandium silylamide complexes.15 These bond lengths are
shorter than the Sc–N bond distances from the pyrazole rings,
thus confirming that the N atoms of the silylamide ligands are
attached to the scandium centre in an anionic fashion. The
X-ray diffraction study confirmed the presence of the two
b-(Si–H) agostic interactions from the same silylamide ligand
(symmetric disposition) in the solid state.13 Thus, the Sc(1)–N(7)
bond distance in 1, 2.041(5) Å, is shorter than those in
[Sc{N(SiHMe2)2}3] (average 2.069 Å).12b The Sc(1)ꢂ ꢂ ꢂSi(3) and
Sc(1)ꢂ ꢂ ꢂSi(4) distances of 3.086(3) Å and 3.207(2) Å are compar-
able with those in the precursor [2.989(1)–3.052(1)]12b and are
shorter than the bond distances of Sc(1)–Si(1) and Sc(1)–Si(2) of
3.312(2) Å and 3.321(2) Å, respectively, for the non-interacting
silylamide ligand. These symmetric b-(Si–H) agostic inter-
actions form two fused four-membered rings, Sc(1)–N(7)–Si(4)–H
and Sc(1)–N(7)–Si(3)–H, with a dihedral angle of 4.551 (similar to
other symmetric b-(Si–H) agostic interactions).13 Furthermore,
relatively acute Sc(1)–N(7)–Si(3) and Sc(1)–N(7)–Si(4) angles of
110.9(3)1 and 118.6(3)1 are observed. Consequently, the Si(3)–
N(7)–Si(4) bond angle, with a value of 129.2(3)1, appears to be
slightly widened.
Entry
Subs.
Cat.
t (h)
Yieldb (%)
TOF (hꢀ1
)
eec (%)
1
2
3
4
5
6
7
8
13
13
13
13
13
13
13
13
13
13
13
13
1-Sca
4-Sca
7-Sca
10-Sca
2-Ya
0.8
0.9
0.9
0.8
0.6
0.6
0.5
0.5
0.7
0.7
0.8
0.7
98
95
92
99
99
98
96
99
98
94
96
95
122.5
105.5
102.2
123.7
165.0
163.3
192.0
198.0
140.0
134.3
120.0
135.7
—
—
—
25
—
—
—
92
—
—
—
99
5-Ya
8-Ya
11-Ya
3-Lua
6-Lua
9-Lua
12-Lua
9
10
11
12
13
14
15
14
14
14
11-Ya
11-Yd
11-Ye
1.0
0.6
0.2
99
99
99
99.0
33.0
49.5
92
93
93
16
17
15
15
11-Ya
11-Y f
24
24
Traces
48
—
—
—
0.2
17
18
16
16
11-Ya
11-Yg
1.5
0.8
99
99
66.0
12.4
—
—
a
b
Hydroamination catalysis
Toluene-d8, 70 1C, [cat]/[substrate] = 1%. NMR yield determined relative
c
to ferrocene as the internal standard. Enantiomeric excess determined by
19F NMR of Mosher amides. Toluene-d8, 70 1C, [cat]/[substrate] = 5%.
d
It is well established that the intramolecular hydroamination/
cyclization now constitutes a particularly powerful and concise
route to functionalized nitrogen heterocycles.16 In fact, signifi-
cant research effort in recent decades has established rare-earth
complexes as being highly active catalysts for this process.16,17
e
f
Toluene-d8, 70 1C, [cat]/[substrate] = 10%. Toluene-d8, 100 1C, [cat]/
g
[substrate] = 10%. Toluene-d8, 100 1C, [cat]/[substrate] = 10%.
for lanthanide-mediated hydroamination, where higher ionic
Complexes 1–12 were tested in catalytic intramolecular radii correlate with higher catalytic activity. Thus, yttrium com-
hydroamination processes. In the initial screening, the reactivity plexes showed the highest activity in the hydroamination/
was tested in the hydroamination of 2,2-diphenyl-4-pentenyl- cyclization of substrate 13 (see TOF values in Table 3). On the
amine (13) (Table 3, entries 1–12). The catalytic activity was other hand, it is worth noting that complexes 10–12, as single
monitored by 1H NMR spectroscopy in toluene-d8 by loading an enantiopure compounds, displayed a remarkable asymmetric
NMR tube with catalyst and substrate at room temperature. The cyclization of substrate 13 with up to 99% ee achieved (see
results presented in Table 3 show distinguished catalytic activity entries 4, 8 and 12 in Table 3). Yttrium catalyst 11 appears to
for compounds 1–12 under mild conditions, with short reaction be the best candidate to examine the scope of complexes 1–12 as
times and a very low catalyst loading. Unfortunately, the catalytic precatalysts. Various aminoalkenes were tested under various
activities of complexes 1–12 in the hydroamination of substrate reaction conditions. Entries 13–15 (Table 3) correspond to the
13 were lower in comparison to the activity found for the results obtained at different [cat]/[substrate] ratios in the hydro-
previously reported hybrid cyclopentadienyl/scorpionate com- amination/cyclization of (1-allylcyclohexyl)methylamine (14),
pounds.10 These complexes adhere to the general trend observed which bears a cyclohexyl unit in the geminal position. For this
7676 | New J. Chem., 2015, 39, 7672--7681
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015

View Article Online
Paper
NJC
substrate, the catalytic activity is lower than that of 13, probably
due to the significant Thorpe–Ingold effect of the geminal
phenyl units in 13. We also considered the hydroamination/
cyclization of an internal 1,2-disubstituted alkene, namely,
(E)-2,2-dimethyl-5-phenyl-4-penten-1-amine (15), to obtain the
cyclic product 19 (Table 3, entries 16 and 17). This cyclization
reaction required much longer reaction times, higher catalyst
loadings and a temperature of 100 1C to obtain even low yields.
We also explored the tandem cyclization reaction of the 2-allyl-2-
methylpent-4-enylamine (16) substrate with compound 11
(Table 3, entries 18 and 19). The allyl-substituted secondary
amine 20 was formed and this did not react further to give the
tertiary amine even when the catalytic reaction was carried out
under more forcing conditions, namely, 100 1C for four days and
with a catalytic loading of 10%. The cyclization of 16 (Table 3,
entries 18 and 19) proceeded to give a quantitative yield and two
diastereoisomers of pyrrolidine 20 were obtained in similar
proportions (Fig. S5, ESI†).
Fig. 7 Linear regression fits for ln[2,2-diphenyl-4-penten-1-amine] (13)
versus time were obtained for the first 30 min. Plot of ln[2,2-diphenyl-4-
penten-1-amine] versus time for several catalyst (11) concentrations
(0.020, 0.025, 0.030, and 0.035 M). The concentration of the substrate
[2-diphenyl-4-penten-1-amine] is 0.40 M.
Quantitative kinetic studies were carried out on the hydro-
amination/cyclization of aminoalkene 13 using 11 as the
catalyst, with the reaction monitored in situ by 1H NMR
spectroscopy (see the ESI†). Linear plots of substrate concen-
tration versus time were obtained for runs in the range of
0.35–0.75 M with the precatalyst concentration kept constant,
indicating that the reaction is zero order in terms of substrate
concentration (Fig. 6). Furthermore, a linear response was
observed for the reaction rate versus precatalyst concentration
with the initial substrate concentration kept constant (Fig. 7
and 8), indicating that the reaction is first order in terms of
catalyst concentration. This empirical rate law is typical of
lanthanide-mediated aminoalkene hydroamination kinetics,
which show zero-order dependence on substrate concen-
tration and first-order dependence on precatalyst concen-
tration.18 The most fruitful comparison is with Marks’
lanthanide systems, for which a wealth of mechanistic infor-
mation is available.18
Fig. 8 Plot of kobs (from Fig. 7) versus concentration of [Y{N(SiHMe2)2}2-
{k3-(S)-mbpam}(thf)] (11) for the cyclization of 2,2-diphenyl-4-penten-1-
amine (13) showing first order dependence on catalyst concentration.
Conclusions
The aim of the work described here was to contribute towards
the ever-growing library of scandium, yttrium and lutetium
compounds and, in particular, that of the less common hetero-
scorpionate organometallic rare-earth metal compounds. Twelve
amide heteroscorpionate compounds were prepared and struc-
turally characterized, both in solution and in the solid state.
Scandium compounds presented a five-coordinate geo-
metry, whereas a molecule of thf is also included with the larger
metal centres (Y and Lu) and this gives rise to six-coordinate
geometries. The highly fluxional nature of the complexes led us
to study the interchange between geometries in both arrange-
ments by VT NMR spectroscopy.
All the new complexes were tested as catalysts for the
hydroamination/cyclization of the aminoalkene 2,2-diphenyl-
4-penten-1-amine. The complexes gave good TOF values, under
mild conditions, with short reaction times and low catalyst
loadings. Amongst them, the yttrium heteroscorpionate single
Fig. 6 Linear regression fits for [2,2-diphenyl-4-penten-1-amine] (13)
versus time were obtained for the first 60 min, indicating that the reactions
are zero-order in substrate concentration. Plot of [2,2-diphenyl-4-penten-
1-amine] versus time, illustrating zero-order dependence on [2,2-diphenyl-
4-penten-1-amine]. The concentration of catalyst 11 is 0.020 M.
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem., 2015, 39, 7672--7681 | 7677

View Article Online
NJC
Paper
enantiopure compound 11 was chosen to examine the scope of d (ppm)): 171.0 (NCQS), 150.6, 142.6 (C3 and 5), 138.8 (Cipso NPh),
these new entities. Very good values for ee are reported for the 129.0 (Cm NPh), 125.6 (Cp NPh), 123.9 (Co NPh), 107.6 (C4), 76.2
yttrium and lutetium single enantiopure compounds (11 and 12). (CH), 15.5 (Me3), 10.9 (Me5), 3.8 (SiMe2). 29Si NMR (C6D6, 297 K):
Finally, three more aminoalkenes were tested to expand the ꢀ22.4 (ds, 1JSiH = 178.1 Hz, 2JSiH = 6.2 Hz, NSiHMe2). IR: n = 2106
substrate scope. Catalyst 11 was successful in the transformation [vs, n(SiH)], 2044 (m, sh), 1602 (vs), 1556 [s, n(CQN)] cmꢀ1
.
of other aminoalkenes but longer reaction times and a higher
catalyst loading were required.
[Y{N(SiHMe2)2}2(j3-pbptam)thf] (2). The synthesis procedure
was the same as for complex 1 using [Y{N(SiHMe2)2}3(thf)2]
(0.40 g, 0.62 mmol) and pbptamH (0.21 g, 0.63 mmol) to obtain
2 as a yellow solid. Yield 90%. Anal. calcd for C30H56N7OSSi4Y: C
47.2, H 7.4, N 12.8. Found: C 47.8, H 7.7, N 12.3. 1H NMR
Experimental
General procedure
3
(500 MHz, C6D6, 297 K): d = 7.03 (s, 1H, CH), 7.40 (d, JH–H
=
3
8.0 Hz, 2H, Ho NPh), 7.26 (t, JH–H = 7.4 Hz, 1H, Hp NPh), 6.92
(m, 2H, Hm NPh), 5.43 (s, 2H, H4), 5.29 (brs, 4H, SiH), 3.94
(m, 4H, thf), 2.51 (s, 6H, Me3), 1.92 (s, 6H, Me5), 1.31 (m, 4H, thf),
0.40 (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz, C6D6, 297 K): d
172.1 (NCQS), 151.1, 142.2 (C3 and 5), 137.8 (Cipso NPh), 129.3
(Cm NPh), 123.6 (Cp NPh), 122.7 (Co NPh), 107.3 (C4), 76.1 (CH),
71.2 (thf), 25.2 (thf), 15.6 (Me3), 11.2 (Me5), 3.9 (SiMe2). 29Si NMR
All manipulations were performed under nitrogen using stan-
dard Schlenk techniques. Solvents were pre-dried over sodium
wire (toluene, n-hexane and THF) and distilled under nitrogen
from sodium (toluene and THF) or sodium-potassium alloy
(n-hexane). Deuterated solvents were stored over activated 4 Å
molecular sieves and degassed by several freeze–thaw cycles.
Microanalyses were carried out with a Perkin-Elmer 2400 CHN
analyzer. 1H, 13C, 29Si and 19F NMR spectra were recorded on a
Varian Inova FT-500 spectrometer. The NOESY-1D spectra were
recorded on a Varian Inova FT-500 with the following acquisi-
tion parameters: irradiation time 2 s and number of scans 256,
using the standard VARIANT-FT software. Two-dimensional
NMR spectra were acquired using standard VARIANT-FT soft-
ware and processed using an IPC-Sun computer. IR spectra
were obtained on a Shimadzu IRPrestige-21 spectrophotometer
equipped with a Pike Technology ATR system. The specific
rotation [a]2D2 was measured at 22 1C on a Perkin-Elmer 241
Polarimeter equipped with a Na lamp operating at 589 nm with
a light path length of 10 cm. ScCl3, YCl3 and LuCl3 were
purchased from Aldrich or Strem. Phenyl isocyanate, phenyl
isothiocyanate, fluoren-2-yl isocyanate, (S)-(ꢀ)-a-methylbenzyl
isocyanate and tert-butyl isothiocyanate were purchased from
Aldrich. The compounds [M{N(SiHMe2)2}3(thf)n],12 bis(3,5-dimethyl-
pyrazol-1-yl)methane (bdmpzm),19 bis(3,5-di-tert-butylpyrazol-1-
yl)methane (bdtbpzm)19 2,2-diphenyl-4-penten-1-amine (13),20
(1-allylcyclohexyl)methylamine (14),20 (E)-2,2-dimethyl-5-phenyl-
4-penten-1-amine (15)20 and 2-allyl-2-methyl-4-penten-1-amine
(16)20 were prepared according to literature procedures.
1
2
(C6D6, 297 K): ꢀ22.5 (ds, JSiH = 177.1 Hz, JSiH = 8.3 Hz,
NSiHMe2). IR: n = 2020 [vs, n(SiH)], 1976 (m, sh), 1677 (vs),
1560 [s, n(CQN)], cmꢀ1
.
[Lu{N(SiHMe2)2}2(j3-pbptam)thf] (3). The synthesis procedure
was the same as for complex 1 using [Lu{N(SiHMe2)2}3(thf)2]
(0.40 g, 0.56 mmol) and pbptamH (0.18 g, 0.56 mmol) to obtain 3
as a yellow solid. Yield 90%. Anal. calcd for C30H56LuN7OSSi4: C
42.4, H 6.6, N 11.5. Found: C 42.3, H 6.6, N 11.4. 1H NMR
3
(500 MHz, C6D6, 297 K): d = 7.23 (s, 1H, CH), 7.20 (d, JH–H
=
3
8.0 Hz, 2H, Ho NPh), 7.14 (t, JH–H = 7.4 Hz, 1H, Hp NPh), 6.83
(m, 2H, Hm NPh), 5.43 (s, 2H, H4), 5.29 (brs, 4H, SiH), 3.56
(m, 4H, thf), 1.82 (s, 6H, Me3), 1.43 (s, 6H, Me5), 1.37 (m, 4H, thf),
0.47 (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz, C6D6, 297 K): d =
184.3 (NCQS), 150.2, 140.8 (C3 and 5), 138.6 (Cipso NPh), 128.6
(Cm NPh), 125.6 (Cp NPh), 129.3 (Co NPh), 106.6 (C4), 64.5 (CH),
69.1 (thf), 25.4 (thf), 13.4 (Me3), 10.1 (Me5), 3.8 (SiMe2). 29Si NMR
1
2
(C6D6, 297 K): ꢀ22.3 (ds, JSiH = 176.2 Hz, JSiH = 6.3 Hz,
NSiHMe2). IR: n = 2124 [vs, n(SiH)], 1995 (m, sh), 1630 (vs),
1536 [s, n(CQN)], cmꢀ1
.
[Sc{N(SiHMe2)2}2(j3-tbptam)] (4). The synthesis procedure
was the same as for complex 1 using [Sc{N(SiHMe2)2}3(thf)]
(0.40 g, 0.78 mmol) and tbptamH (0.25 g, 0.78 mmol) to obtain
4 as a yellow solid. Yield 80%. Anal. calcd for C24H52N7SScSi4: C
45.9, H 8.3, N 15.6. Found: C 46.1, H 8.6, N 15.2. 1H NMR
Synthesis of complexes
[Sc{N(SiHMe2)2}2(j3-pbptam)] (1). In a 100 mL Schlenk tube, (500 MHz, C6D6, 297 K): d = 6.80 (s, 1H, CH), 5.40 (s, 2H, H4),
[Sc{N(SiHMe2)2}3(thf)] (0.40 g, 0.78 mmol) was dissolved in dry 5.40 (brs, 4H, SiH), 2.46 (s, 6H, Me3), 1.89 (s, 6H, Me5), 1.50
toluene (25 mL) and the solution was placed in an ice bath. A (s, 9H, Bu), 0.40 (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz,
t
solution of the thioacetamide pbptamH (0.26 g, 0.78 mmol) in C6D6, 297 K): d = 178.0 (NCQS), 152.7, 144.8 (C3 and 5), 107.0
dry toluene (25 mL) was added. The resulting solution was (C4), 73.5 (CH), 55.4 (C(CH3)3), 16.7 (C(CH3)3), 12.9 (Me3), 10.8
stirred for 2 h at 0 1C. The solvent was removed under vacuum (Me5), 3.5 (SiMe2). 29Si NMR (C6D6, 297 K): ꢀ23.4 (ds, JSiH
=
1
and the solid was washed with hexane. The resulting solid was 175.2 Hz, 2JSiH = 6.0 Hz, NSiHMe2). IR: n = 2048 [vs, n(SiH)], 2114
crystallized from a mixture of toluene/hexane to obtain yellow (m, sh), 1651 (vs), 1545 [s, n(CQN)], cmꢀ1
crystals. Yield 90%. Anal. calcd for C26H48N7SScSi4: C 48.2, H
[Y{N(SiHMe2)2}2(j3-tbptam)thf] (5). The synthesis procedure
.
1
7.4, N 15.1. Found: C 48.5, H 7.3, N 15.2. H NMR (500 MHz, was the same as for complex 1 using [Y{N(SiHMe2)2}3(thf)2]
C6D6, 297 K): d = 7.09 (s, 1H, CH), 7.41 (d, 3JH–H = 7.8 Hz, 2H, Ho (0.40 g, 0.63 mmol) and tbptamH (0.20 g, 0.63 mmol) to obtain
NPh), 7.15 (t, 3JH–H = 7.2 Hz, 1H, Hp NPh), 7.02 (m, 2H, Hm NPh), 5 as a yellow solid. Yield 85%. Anal. calcd for C28H60N7OSSi4Y:
5.38 (s, 2H, H4), 5.11 (brs, 4H, SiH), 2.49 (s, 6H, Me3), 1.87 C 45.2, H 8.1, N 13.2. Found: C 45.7, H 8.5, N 13.0. H NMR
1
(s, 6H, Me5), 0.39 (brs, 24H, SiMe2). 13C{1H} NMR (C6D6, 297 K; (500 MHz, C6D6, 297 K): d = 7.03 (s, 1H, CH), 5.49 (s, 2H, H4),
7678 | New J. Chem., 2015, 39, 7672--7681
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015

View Article Online
Paper
NJC
5.10 (brs, 4H, SiH), 3.95 (m, 4H, thf), 2.48 (s, 6H, Me3), 1.93 as a white solid. Yield 85%. Anal. calcd for C30H56N7LuO2Si4: C
(s, 6H, Me5), 1.42 (s, 9H, tBu), 1.42 (m, 4H, thf), 0.35 (brs, 24H, 43.2, H 6.7, N 11.7. Found: C 43.9, H 7.0, N 11.2. 1H NMR
3
SiMe2). 13C{1H} NMR (125 MHz, C6D6, 297 K): d = 179.5 (500 MHz, C6D6, 297 K): d = 6.97 (s, 1H, CH), 7.24 (d, JH–H
=
3
(NCQS), 152.4, 141.5 (C3 and 5), 107.2 (C4), 74.1 (CH), 66.2 7.5 Hz, 2H, Ho NPh), 7.11 (t, JH–H = 7.1 Hz, 1H, Hp NPh), 6.90
(thf), 25.8 (thf), 55.1 (C(CH3)3), 17.4 (C(CH3)3), 12.5 (Me3), 11.6 (m, 2H, Hm NPh), 5.47 (s, 2H, H4), 5.15 (brs, 4H, SiH), 3.83
1
(Me5), 3.3 (SiMe2). 29Si NMR (C6D6, 297 K): –23.3 (ds, JSiH
=
(m, 4H, thf), 2.45 (s, 6H, Me3), 1.77 (s, 6H, Me5), 1.36 (m, 4H, thf),
177.4 Hz, 2JSiH = 7.3 Hz, NSiHMe2). IR: n = 2068 [vs, n(SiH)], 1955 0.37 (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz, C6D6, 297 K): d =
(m, sh), 1657 (vs), 1540 [s, n(CQN)], cmꢀ1
.
157.5 (NCQO), 155.5, 141.6 (C3 and 5), 152.1 (Cipso NPh), 129.2
[Lu{N(SiHMe2)2}2(j3-tbptam)thf] (6). The synthesis procedure (Cm NPh), 125.7 (Cp NPh), 124.9 (Co NPh), 108.4 (C4), 71.9 (CH),
was the same as for complex 1 using [Lu{N(SiHMe2)2}3(thf)2] 66.9 (thf), 27.4 (thf), 14.1 (Me3), 11.4 (Me5), 3.1 (SiMe2). 29Si NMR
1
2
(0.40 g, 0.56 mmol) and tbptamH (0.18 g, 0.56 mmol) to obtain 6 (C6D6, 297 K): ꢀ24.3 (ds, JSiH = 175.8 Hz, JSiH = 7.3 Hz,
as a yellow solid. Yield 80%. Anal. calcd for C28H60LuN7OSSi4: C NSiHMe2). IR: n = 2110 [vs, n(SiH)], 1980 (m, sh), 1659 (vs),
40.5, H 7.3, N 11.8. Found: C 40.9, H 7.8, N 11.4. 1H NMR 1578 [s, n(CQN)], cmꢀ1
.
(500 MHz, C6D6, 297 K): d = 6.75 (s, 1H, CH), 5.25 (s, 2H, H4), 5.90
[Sc{N(SiHMe2)2}2{j3-(S)-mbpam}] (10). The synthesis proce-
(brs, 4H, SiH), 3.76 (m, 4H, thf), 2.30 (s, 6H, Me3), 1.73 (s, 6H, dure was the same as for complex 1 using [Sc{N(SiHMe2)2}3(thf)]
Me5), 1.33 (m, 4H, thf), 1.30 (s, 9H, Bu), 0.37 (brs, 24H, SiMe2). (0.40 g, 0.78 mmol) and (S)-mbpamH (0.27 g, 0.78 mmol) to
t
13C{1H} NMR (125 MHz, C6D6, 297 K): d = 169.0 (NCQS), 150.6, obtain 10 as a white solid. Yield 88%. [a]2D5 = ꢀ31.3 (c 0.10,
143.0 (C3 and 5), 107.4 (C4), 78.6 (CH), 67.5 (thf), 28.4 (thf), 58.7 toluene). Anal. calcd for C28H52N7OScSi4: C 51.0, H 8.0, N 14.9.
(C(CH3)3), 11.3 (C(CH3)3), 15.0 (Me3), 11.9 (Me5), 3.6 (SiMe2). 29Si Found: C 51.5, H 8.2, N 14.6. H NMR (500 MHz, C6D6, 297 K):
1
1
2
NMR (C6D6, 297 K): ꢀ22.6 (ds, JSiH = 175.4 Hz, JSiH = 6.2 Hz, d = 6.96 (s, 1H, CH), 7.37–7.00 (m, 5H, NCH(CH3)Ph), 5.63
NSiHMe2). IR: n = 2078 [vs, n(SiH)], 1990 (m, sh), 1648 (vs), 1565 (m, 1H, NCH(CH3)Ph), 5.45, 5.42 (s, 2H, H4,40), 5.35 (brs, 4H,
[s, n(CQN)], cmꢀ1
.
SiH), 1.90, 2.28 (s, 3H each, Me3,30), 1.83, 2.25 (s, 3H each,
[Sc{N(SiHMe2)2}2(j3-pbpam)] (7). The synthesis procedure Me5,50), 1.60 (d, JH–H = 6.5 Hz, 3H, NCH(CH3)Ph), 0.39
was the same as for complex 1 using [Sc{N(SiHMe2)2}3(thf)] (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz, C6D6, 297 K):
(0.40 g, 0.78 mmol) and pbpamH (0.25 g, 0.78 mmol) to obtain d = 161.5 (NCQO), 148.9, 148.7, 141.5, 141.2 (C3,30 or 5,50),
7 as a white solid. Yield 85%. Anal. calcd for C26H48N7OScSi4: C 146.9 (Cipso NCH(CH3)Ph), 128.3 (Cm NCH(CH3)Ph), 126.9
3
49.4, H 7.6, N 15.5. Found: C 49.8, H 7.9, N 15.1. 1H NMR (Cp NCH(CH3)Ph), 127.4 (Co NCH(CH3)Ph), 106.3, 106.0 (C4,40),
3
(500 MHz, C6D6, 297 K): d = 6.96 (s, 1H, CH), 7.25 (d, JH–H
=
69.5 (CH), 51.4 (NCH(CH3)Ph), 24.9 (NCH(CH3)Ph), 13.6, 13.5
7.8 Hz, 2H, Ho NPh), 7.17 (t, JH–H = 7.2 Hz, 1H, Hp NPh), 6.87 (Me3,30), 11.4, 11.3 (Me5,50), 3.4 (SiMe2). 29Si NMR (C6D6, 297 K):
(m, 2H, Hm NPh), 5.48 (s, 2H, H4), 5.01 (brs, 4H, SiH), 2.29 ꢀ24.8 (ds, 1JSiH = 173.5 Hz, 2JSiH = 6.7 Hz, NSiHMe2). IR: n = 2015
3
(s, 6H, Me3), 1.74 (s, 6H, Me5), 0.39 (brs, 24H, SiMe2). 13C{1H} [vs, n(SiH)], 1989 (m, sh), 1612 (vs), 1592 [s, n(CQN)], cmꢀ1
.
NMR (125 MHz, C6D6, 297 K): d = 157.0 (NCQO), 150.6, 149.7
[Y{N(SiHMe2)2}2{j3-(S)-mbpam}thf] (11). The synthesis proce-
(C3 and 5), 152.7 (Cipso NPh), 129.3 (Cm NPh), 124.0 (Cp NPh), dure was the same as for complex 1 using [Y{N(SiHMe2)2}3(thf)2]
122.6 (Co NPh), 107.7 (C4), 70.9 (CH), 14.5 (Me3), 10.9 (Me5), 2.9 (0.40 g, 0.63 mmol) and (S)-mbpamH (0.22 g, 0.63 mmol) to
(SiMe2). 29Si NMR (C6D6, 297 K): ꢀ23.1 (ds, JSiH = 170.2 Hz, obtain 11 as a white solid. Yield 85%. [a]2D5 = ꢀ24.6 (c 0.10,
1
2JSiH = 6.0 Hz, NSiHMe2). IR: n = 2050 [vs, n(SiH)], 2108 (m, sh), toluene). Anal. calcd for C32H60N7O2Si4Y: C 49.5, H 7.8, N 12.6.
1650 (vs), 1545 [s, n(CQN)], cmꢀ1
.
Found: C 49.9, H 8.1, N 12.0. H NMR (500 MHz, C6D6, 297 K):
1
[Y{N(SiHMe2)2}2(j3-pbpam)thf] (8). The synthesis procedure d = 6.87 (s, 1H, CH), 7.35–7.00 (m, 5H, NCH(CH3)Ph), 5.57
was the same as for complex 1 using [Y{N(SiHMe2)2}3(thf)2] (m, 1H, NCH(CH3)Ph), 5.50, 5.48 (s, 2H, H4,40), 5.30 (brs, 4H,
(0.40 g, 0.63 mmol) and pbpamH (0.20 g, 0.63 mmol) to obtain SiH), 3.30 (m, 4H, thf), 1.97, 2.31 (s, 3H each, Me3,30), 1.95, 2.28
8 as a white solid. Yield 85%. Anal. calcd for C30H56N7O2Si4Y: C (s, 3H each, Me5,50), 1.62 (d, JH–H = 6.6 Hz, 3H, NCH(CH3)Ph),
3
48.2, H 7.5, N 13.1. Found: C 48.6, H 7.9, N 12.8. 1H NMR 1.22 (m, 4H, thf), 0.39 (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz,
3
(500 MHz, C6D6, 297 K): d = 6.72 (s, 1H, CH), 7.55 (d, JH–H
=
C6D6, 297 K): d = 162.2 (NCQO), 148.7, 148.6, 141.1, 141.0
7.8 Hz, 2H, Ho NPh), 7.14 (t, JH–H = 7.2 Hz, 1H, Hp NPh), 7.03 (C3,30 or5,50), 146.8 (Cipso NCH(CH3)Ph), 128.8 (Cm NCH(CH3)Ph),
(m, 2H, Hm NPh), 5.46 (s, 2H, H4), 5.12 (brs, 4H, SiH), 3.84 126.7 (Cp NCH(CH3)Ph), 127.3 (Co NCH(CH3)Ph), 106.2, 106.0
(m, 4H, thf), 2.45 (s, 6H, Me3), 1.79 (s, 6H, Me5), 1.35 (m, 4H, thf), (C4,40), 69.6 (CH), 68.4 (thf), 25.2 (thf), 51.3 (NCH(CH3)Ph), 22.3
0.36 (brs, 24H, SiMe2). 13C{1H} NMR (125 MHz, C6D6, 297 K): d = (NCH(CH3)Ph), 13.3, 13.0 (Me3,30), 11.2, 11.1 (Me5,50), 3.3 (SiMe2).
158.3 (NCQO), 152.8, 147.8 (C3 and 5), 151.4 (Cipso NPh), 128.8 29Si NMR (C6D6, 297 K): ꢀ25.1 (ds, 1JSiH = 177.3 Hz, 2JSiH = 6.0 Hz,
(Cm NPh), 124.7 (Cp NPh), 120.3 (Co NPh), 106.9 (C4), 71.2 (CH), NSiHMe2). IR: n = 2101 [vs, n(SiH)], 1963 (m, sh), 1632 (vs), 1540
3
67.7 (thf), 25.5 (thf), 13.7 (Me3), 10.5 (Me5), 2.8 (SiMe2). 29Si NMR [s, n(CQN)], cmꢀ1
.
1
2
(C6D6, 297 K): ꢀ24.5 (ds, JSiH = 170.3 Hz, JSiH = 6.9 Hz,
[Lu{N(SiHMe2)2}2{j3-(S)-mbpam}thf] (12). The synthesis
NSiHMe2). IR: n = 1990 [vs, n(SiH)], 1931 (m, sh), 1675 (vs), procedure was the same as for complex 1 using [Lu{N(SiH-
1587 [s, n(CQN)], cmꢀ1
Me2)2}3(thf)2] (0.40 g, 0.56 mmol) and (S)-mbpamH (0.20 g,
[Lu{N(SiHMe2)2}2(j3-pbpam)thf] (9). The synthesis procedure 0.56 mmol) to obtain 12 as a white solid. Yield 84%. [a]2D5
.
=
was the same as for complex 1 using [Lu{N(SiHMe2)2}3(thf)2] ꢀ36.1 (c 0.10, toluene). Anal. calcd for C32H60LuN7O2Si4: C 44.6,
(0.40 g, 0.56 mmol) and pbpamH (0.18 g, 0.56 mmol) to obtain 9 H 7.0, N 11.4. Found: C 44.8, H 7.5, N 11.0. 1H NMR (500 MHz,
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem., 2015, 39, 7672--7681 | 7679

View Article Online
NJC
Paper
C6D6, 297 K): d = 6.89 (s, 1H, CH), 7.40–7.00 (m, 5H, Notes and references
NCH(CH3)Ph), 5.65 (m, 1H, NCH(CH3)Ph), 5.56, 5.54 (s, 2H,
1 (a) D. A. Atwood, The Rare Earth Elements: Fundamentals and
Application, John Wiley & Sons, Ltd, 2013; (b) S. Cotton,
Lanthanide and Actinide Chemistry, John Wiley & Sons, Ltd,
2006.
H4,40), 5.25 (brs, 4H, SiH), 3.25 (m, 4H, thf), 1.95, 2.31 (s, 3H
3
each, Me3,30), 1.88, 2.28 (s, 3H each, Me5,50), 1.65 (d, JH–H
=
=
3
6.6 Hz, 3H, NCH(CH3)Ph), 1.20 (m, 4H, thf), 0.56 (d, JH–H
3
3.2 Hz, 12H, SiMe2), 0.50 (d, JH–H = 3.1 Hz, 12H, SiMe2).
13C{1H} NMR (125 MHz, C6D6, 297 K): d = 162.0 (NCQO),
148.9, 148.8, 141.3, 141.0 (C3,30 or 5,50), 146.8 (Cipso NCH(CH3)Ph),
128.3 (Cm NCH(CH3)Ph), 126.8 (Cp NCH(CH3)Ph), 127.8
(Co NCH(CH3)Ph), 106.4, 106.1 (C4,40), 69.7 (CH), 68.5 (thf),
22.5 (thf), 51.4 (NCH(CH3)Ph), 22.5 (NCH(CH3)Ph), 13.4, 13.3
(Me3,30), 11.3, 11.2 (Me5,50), 3.5 (SiMe2). 29Si NMR (C6D6, 297 K):
ꢀ23.8 (ds, 1JSiH = 172.1 Hz, 2JSiH = 6.4 Hz, NSiHMe2). IR: n = 1998
2 See as examples: (a) G. Zhang, Y. Wei, L. Guo, X. Zhu,
S. Wang, S. Zhou and X. Mu, Chem. – Eur. J., 2015, 21, 2519;
(b) F. T. Edelmann, Coord. Chem. Rev., 2014, 26, 173;
(c) F. T. Edelmann, Chem. Soc. Rev., 2012, 41, 7657;
(d) J. Gromada, J. F. Carpentier and A. Mortreux, Coord.
Chem. Rev., 2004, 248, 397; (e) S. Hong and T. J. Marks, Acc.
Chem. Res., 2004, 37, 673; ( f ) Z. M. Hou and Y. Wakatsuki,
Coord. Chem. Rev., 2002, 231, 1; (g) S. Arndt and J. Okuda,
Chem. Rev., 2002, 102, 1953; (h) G. A. Molander and
J. A. C. Romero, Chem. Rev., 2002, 102, 2161.
[vs, n(SiH)], 1976 (m, sh), 1682 (vs), 1535 [s, n(CQN)], cmꢀ1
.
General procedure for catalytic intramolecular hydroamination
3 See as examples: (a) J.-F. Liu, F.-X. Pan, S. Yao, X. Min,
D. Cui and Z.-M. Sun, Organometallics, 2014, 33, 1374; (b)
P.-H. Wei, L. Xu, L.-C. Song, W.-X. Zhang and Z. Xi,
Organometallics, 2014, 33, 2784; (c) Y. Luo, S. Chi and
J. Chen, New J. Chem., 2013, 37, 2675; (d) M. Zimmermann
and R. Anwander, Chem. Rev., 2010, 110, 6194; (e) K. C.
Jantunen, B. L. Scott, J. C. Gordon and J. L. Kiplinger,
Organometallics, 2007, 26, 2777; ( f ) L. Zhang, Y. Luo and
Z. Hou, J. Am. Chem. Soc., 2005, 127, 14562.
In a typical small scale experiment, 0.01 mmol (0.0065 g) of catalyst
[Sc{N(SiHMe2)2}2(k3-pbptam)] (1) and 1.00 mmol (0.2377 g) of
aminoalkene 2,2-diphenyl-4-penten-1-amine (13)20 were dis-
solved in toluene-d8 (0.75 mL) and placed in a J. Young-style
NMR tube with a re-sealable Teflon valve. The tube was closed
and placed into an oil bath that was preheated at the desired
temperature. The reaction was monitored at regular intervals by
1H NMR spectroscopy to determine the optimum conversion.
4 See as examples: (a) B. Liu, L. Li, G. Sun, J. Liu, M. Wang,
S. Li and D. Cui, Macromolecules, 2014, 47, 4971; (b) M. Hasegawa,
H. Ohtsu, D. Kodama, T. Kasai, S. Sakurai, A. Ishiia and
K. Suzukic, New J. Chem., 2014, 38, 1225; (c) H.-M. Ye, N. Ren,
J.-J. Zhang, S.-J. Sun and J.-F. Wang, New J. Chem., 2010, 34, 533;
(d) W. E. Piers and D. J. H. Emslie, Coord. Chem. Rev., 2002,
131, 233.
5 (a) N. Marques, A. Sella and J. Takats, Chem. Rev., 2002,
102, 2137; (b) F. T. Edelmann, Angew. Chem., Int. Ed., 2001,
40, 1656; (c) I. Santos and N. Marques, New J. Chem., 1995,
19, 551.
X-ray crystallographic structure determination
A summary of crystal data collection and refinement parameters
is given in Table 1. Single crystals of 1 were mounted on a glass
fibre and transferred to a Bruker X8 APEX II CCD-based diffracto-
meter equipped with a graphite monochromated Mo-Ka radia-
tion source (l = 0.71073 Å). For this compound, only crystals of
low quality (Rint = 0.196) could be grown and the crystal diffracted
poorly. Data were integrated using SAINT21 and an absorption
correction was performed with the program SADABS.22 The soft-
ware package SHELXTL version 6.1023 was used for space group
determination, structure solution and refinement by full-matrix
least-squares methods based on F2. The one SiMe3 group showed
disorder, which was modelled on three positions using the DELU
and SIMU instructions. All non-hydrogen atoms were refined
with anisotropic thermal parameters. Except for the hydrogen
atoms of Si atoms, the hydrogen atoms were included in the
structure factor calculation at idealized positions and were
allowed to ride on the neighbouring atoms with relative isotropic
displacement coefficients. The hydrogen atoms of Si atoms have
been included in an idealized position with a Si–H distance of
1.4 Å and then fixed.
´
´
´
6 (a) I. Marquez-Segovia, A. Lara-Sanchez, A. Otero, J. Fernandez-
´
Baeza, J. A. Castro-Osma, L. F. Sanchez-Barba and A. M.
´
Rodrıguez, Dalton Trans., 2014, 43, 9586; (b) A. Otero,
´
´
´
J. Fernandez-Baeza, A. Lara-Sanchez and L. F. Sanchez-Barba,
Coord. Chem. Rev., 2013, 257, 1806.
´
7 See as examples: (a) M. Honrado, A. Otero, J. Fernandez-
´
´
´
Baeza, L. F. Sanchez-Barba, A. Garces, A. Lara-Sanchez and
´
A. M. Rodrıguez, Organometallics, 2014, 33, 1859; (b) M. Honrado,
´
´
A. Otero, J. Fernandez-Baeza, L. F. Sanchez-Barba, A. Lara-
´
´
´
´
Sanchez, J. Tejeda, M. P. Carrion, J. Martınez-Ferrer, A. Garces
´
and A. M. Rodrıguez, Organometallics, 2013, 32, 3437;
(c) Z. Zhang and D. Cui, Chem. – Eur. J., 2011, 17, 11520;
´
(d) A. Otero, J. Fernandez-Baeza, J. Tejeda, A. Lara-Sanchez,
´
´
´
S. Franco, J. Martınez-Ferrer, M. P. Carrion, I. Lopez-Solera,
Acknowledgements
´
´
A. M. Rodrıguez and L. F. Sanchez-Barba, Inorg. Chem.,
2011, 50, 1826; (e) G. Tu¨rkoglu, C. P. Ulldemolins,
R. Mu¨ller, E. Hu¨bener, F. W. Heinemann, M. Wolf and
N. Burzlaff, Eur. J. Inorg. Chem., 2010, 2962; ( f ) A. Otero,
J. Fernandez-Baeza, J. Tejeda, A. Lara-Sanchez, M. Sanchez-
Molina, S. Franco, M. I. Lopez-Solera, A. M. Rodrıguez,
We gratefully acknowledge financial support from the
Ministerio de Economia y Competitividad (MINECO), Spain
(Grant No. CTQ2011-22578 and CTQ2014-51912-REDC) and
the Junta de Comunidades de Castilla-La Mancha, Spain (Grant
No. PEII-2014-013-A).
´
´
´
´
7680 | New J. Chem., 2015, 39, 7672--7681
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015

View Article Online
Paper
NJC
´
´
L. Sanchez-Barba, S. Morante-Zarcero and A. Garces, Inorg. 13 (a) H. J. Yuen and T. J. Marks, Organometallics, 2008,
Chem., 2009, 48, 5540; (g) R.-Y. Tan, J. Hong, M. Du and
L.-F. Tang, J. Organomet. Chem., 2007, 692, 1708; (h) R. G.
Howe, C. S. Tredget, S. C. Lawrence, S. Subongkoj, A. R.
Cowley and P. Mountford, Chem. Commun., 2006, 223.
27, 155; (b) W. Hieringer, J. Eppinger, R. Anwander and
W. A. Herrmann, J. Am. Chem. Soc., 2000, 122, 11983;
(c) L. J. Procopio, P. J. Carroll and D. H. Berry, J. Am. Chem.
Soc., 1994, 116, 177.
´
˜
˜
8 A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara- 14 (a) M.-A. Munoz-Hernandez, T. S. Keizer, P. Wei, S. Parkin
´
´
´
Sanchez, L. Sanchez-Barba, E. Martınez-Caballero, A. M.
and D. A. Atwood, Inorg. Chem., 2001, 40, 6782; (b) J. Muller
and R. Boese, J. Mol. Struct., 2000, 520, 215.
´
´
Rodrıguez and I. Lopez-Solera, Inorg. Chem., 2005, 44, 5336.
´
´
9 (a) A. Otero, A. Lara-Sanchez, J. Fernandez-Baeza, C. Alonso- 15 (a) H. Ma, T. P. Spaniol and J. Okuda, Angew. Chem., Int. Ed.,
´
´
Moreno, I. Marquez-Segovia, L. F. Sanchez-Barba, J. A.
2006, 45, 7818; (b) C. S. Tredgdet, S. C. Lawrence,
B. D. Ward, G. R. Howe, A. R. Cowley and P. Mountford,
Organometallics, 2005, 24, 3136; (c) H. Ma, T. P. Spaniol and
J. Okuda, Dalton Trans., 2003, 4770; (d) F. Estler,
E. Herdtwck and R. Anwander, J. Chem. Soc., Dalton Trans.,
2002, 3088; (e) P. B. Hitchcock, M. F. Lappert and A. Singh,
J. Chem. Soc., Chem. Commun., 1983, 1499.
´
Castro-Osma and A. M. Rodrıguez, Dalton Trans., 2011,
40, 4687; (b) A. Otero, A. Lara-Sanchez, J. Fernandez-Baeza,
E. Martınez-Caballero, I. Marquez-Segovia, C. Alonso-
Moreno, L. F. Sanchez-Barba, A. M. Rodrıguez and
I. Lopez-Solera, Dalton Trans., 2010, 39, 930; (c) A. Otero,
J. Fernandez-Baeza, A. Lara-Sanchez, C. Alonso-Moreno,
´
´
´
´
´
´
´
´
´
´
´
I. Marquez-Segovia, L. F. Sanchez-Barba and A. M. 16 (a) T. E. Mu¨ller, K. C. Hultzsch, M. Yus, F. Foubelo and
´
Rodrıguez, Angew. Chem., 2009, 48, 2176; (d) A. Otero,
M. Tada, Chem. Rev., 2008, 108, 3795; (b) F. Pohlki and
S. Doye, Chem. Soc. Rev., 2003, 32, 104; (c) J. J. Brunet and
D. Neibecker, in Catalytic Heterofunctionalization, ed.
A. Togni and H. Gruetzmacher, Wiley-VCH, Weinheim,
Germany, 2001, pp. 91–141.
´
´
˜
J. Fernandez-Baeza, A. Lara-Sanchez, A. Antinolo,
J. Tejeda, E. Martınez-Caballero, I. Marquez-Segovia,
´
´
´
´
I. Lopez-Solera, L. F. Sanchez-Barba and C. Alonso-
Moreno, Inorg. Chem., 2008, 47, 4996; (e) A. Otero,
´
˜
´
J. Fernandez-Baeza, A. Antinolo, A. Lara-Sanchez, 17 See as examples: (a) K. Manna, A. Ellern and A. D. Sadow,
´
´
E. Martınez-Caballero, J. Tejeda, L. F. Sanchez-Barba,
Chem. Commun., 2010, 46, 33; (b) D. C. Leitch, P. R. Payne,
C. R. Dunbar and L. L. Schafer, J. Am. Chem. Soc., 2009,
131, 18246; (c) B. D. Stubber and T. J. Marks, J. Am. Chem.
Soc., 2007, 129, 6149; (d) D. V. Gribkov and K. C. Hultzsch,
Angew. Chem., Int. Ed., 2004, 43, 5542; (e) J.-S. Li, Y. Ryu and
T. J. Marks, J. Am. Chem. Soc., 2003, 125, 12584.
´
C. Alonso-Moreno and I. Lopez-Solera, Organometallics,
´
´
2008, 27, 976; ( f ) A. Lara-Sanchez, A. Rodrıguez, D. L.
Hughes, M. Schormann and M. Bochmann, J. Organomet.
Chem., 2002, 663, 63.
´
´
´
10 A. Otero, A. Lara-Sanchez, C. Najera, J. Fernandez-Baeza,
´
´
´
I. Marquez-Segovia, J. A. Castro-Osma, J. Martınez, 18 See as examples: (a) M. R. Gagne, C. L. Stern and T. J. Marks,
´
´
´
L. F. Sanchez-Barba and A. M. Rodrıguez, Organometallics,
J. Am. Chem. Soc., 1992, 114, 275; (b) M. R. Gagne and
2012, 31, 2244.
T. J. Marks, J. Am. Chem. Soc., 1989, 111, 4108–4109.
´
´
11 (a) A. Otero, A. Lara-Sanchez, J. Fernandez-Baeza, C. Alonso- 19 (a) A. Beck, B. Weibert and N. Burzlaff, Eur. J. Inorg. Chem.,
´
´
´
Moreno, J. A. Castro-Osma, I. Marquez-Segovia,
2001, 521; (b) E. Dıez-Barra, A. de la Hoz, A. Sanchez-
Migallon and J. Tejeda, J. Chem. Soc., Perkin Trans. 1,
1993, 1079; (c) J. Sebastian, P. Sala, J. Del Mazo,
M. Sancho, C. Ochia, J. Elguero, J. P. Fayet and
M. C. Vertut, Heterocycl. Chem., 1982, 19, 1141.
´
´
´
L. F. Sanchez-Barba, A. M. Rodrıguez and J. C. Garcıa-
Martınez, Organometallics, 2011, 30, 1507; (b) A. Otero,
A. Lara-Sanchez, J. Fernandez-Baeza, C. Alonso-Moreno,
J. Tejeda, J. A. Castro-Osma, I. Marquez-Segovia, L. F.
´
´
´
´
´
´
´
Sanchez-Barba, A. M. Rodrıguez and M. V. Gomez, Chem. 20 P. Hornillo-Martinez, K. C. Hultzsch and F. Hampel, Chem.
– Eur. J., 2010, 16, 8615. Commun., 2006, 2221.
12 (a) S. Arndt, T. P. Spaniol and J. Okuda, Chem. Commun., 2002, 21 SAINT + v7.12a, Area-Detector Integration Program, Bruker-
896; (b) R. Anwander, O. Runte, J. Eppinger, G. Gerstberger, Nonius AXS, Madison, Wisconsin, USA, 2004.
E. Herdtweck and M. Spiegler, J. Chem. Soc., Dalton Trans., 1998, 22 G. M. Sheldrick, SADABS version 2004/1, A Program for
¨
Empirical Absorption Correction, University of Gottingen,
847; (c) J. L. Atwood, W. E. Hunter, R. D. Rogers, J. Holton,
J. McMeeking, R. Pearce and M. F. Lappert, J. Chem. Soc., Chem.
¨
Gottingen, Germany, 2004.
Commun., 1978, 140; (d) M. F. Lappert and R. Pearce, J. Chem. 23 SHELXTL-NT version 6.12, Structure Determination Package,
Soc., Chem. Commun., 1973, 126. Bruker-Nonius AXS, Madison, Wisconsin,USA, 2001.
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem., 2015, 39, 7672--7681 | 7681