Synthesis and characterization of organolanthanide complexes with a calix[4]-pyrrolyl ligand and their catalytic activities toward hydrophosphonylation of aldehydes and unactivated ketones

Article abstract of DOI:10.1021/om2008925

The alkali metal salt free dinuclear trivalent lanthanide amido complexes (η⁵:η¹:η⁵:η¹-Et ₈-calix[4]-pyrrolyl){LnN(SiMe₃)₂}₂ (Ln = Nd (2), Sm (3), Gd (4)) were prepare

Full text of DOI:10.1021/om2008925

Article
pubs.acs.org/Organometallics
Synthesis and Characterization of Organolanthanide Complexes with
a Calix[4]-pyrrolyl Ligand and Their Catalytic Activities toward
Hydrophosphonylation of Aldehydes and Unactivated Ketones
Shuangliu Zhou,† Hengyu Wang,† Jian Ping,† Shaowu Wang,*,†,‡ Lijun Zhang,*,† Xiancui Zhu,†
Yun Wei,† Fenhua Wang,† Zhijun Feng,† Xiaoxia Gu,† Song Yang,† and Hui Miao†
†Laboratory of Functionalized Molecular Solids, Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Institute of
Organic Chemistry, College of Chemistry and Materials Science, Anhui Normal University, Wuhu, Anhui 241000, People's Republic
of China
‡State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Shanghai 200032, People's Republic of
China
S
* Supporting Information
ABSTRACT: The alkali metal salt free dinuclear trivalent lanthanide amido complexes (η5:η1:η5:η1-Et8-calix[4]-pyrrolyl){LnN-
(SiMe3)2}2 (Ln = Nd (2), Sm (3), Gd (4)) were prepared through the silylamine elimination reactions of calix[4]-pyrrole
[Et2C(C4H2NH)]4 (1) with 2 equiv of [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln = Nd, Sm, Gd) in toluene at 110 °C. The
complexes were fully characterized by elemental, spectroscopic, and single-crystal X-ray analyses. Studies on the catalytic activity
of the new lanthanide amido complexes revealed that these complexes can be used as efficient catalysts for hydrophosphonylation
of aldehydes and unactivated ketones, affording the products in high yields by employing a low catalyst loading (0.1 mol %) at
room temperature in a short time (20 min). Noteworthy is that it is the first application of calix[4]-pyrrolyl-supported lanthanide
amides as catalysts to catalyze the hydrophosphonylation of aldehydes and unactivated ketones under mild conditions.
elimination reaction of the corresponding calix[4]-pyrroles
with lanthanide amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3; these
complexes showed good controllability on the ring-opening
polymerization of L-lactide.5
INTRODUCTION
■
The employment of the calix[4]-pyrrolyl ligand is particularly
appropriate for the high coordination numbers of lanthanide
metals and hard donor atoms.1 Each pyrrolyl anion can not
only bond with metal in an η5 or η3 bonding mode through π
electrons but also coordinate to lanthanide ions through lone-
pair electrons of the nitrogen atom of the pyrrolyl ring. The
divalent lanthanide complexes containing calix[4]-pyrrolyl
ligands have been widely synthesized and applied in small
molecule activation, such as reduction of N2 or reversible
fixation of ethylene.2 However, the preparation of trivalent
lanthanide complexes with calix[4]-pyrrolyl tetra-anion ligands
usually resulted in a combination of the alkali metal salts
through the metathesis reaction.3 To avoid the combination of
alkali metal salts in these complexes, the N-methyl substituents
of the calix[4]-pyrrole has been introduced to lanthanide
chemistry for the synthesis of the mononuclear calix[4]-pyrrolyl
lanthanide amido complexes.4 More recently, we have also
reported that the alkali-metal-free bent-sandwich lanthanide
amido complexes with Me8- or {-(CH2)5-}4-calix[4]-pyrrolyl
ligands could be obtained through the direct silylamine
The development of an efficient method for the synthesis of
α-hydroxy phosphonates has become a field of interest due to
their potential biological activities.6 The direct addition of
dialkyl phosphites to carbonyl compounds (Pudovik reaction)
is an efficient way for the synthesis of α-hydroxy phosphonates
with good selectivity and high atomic efficiency.7 Various metal
complexes, including aluminum,8 titanium,9 lanthanide,10
niobium,11 and molybdenum complexes,12 have been demon-
strated to be the effective catalysts for hydrophosphonylation of
aldehydes. However, ketones remain a challenging class of
substrates for the hydrophosphonylation reaction, because they
display a low reactivity toward dialkyl phosphites compared
with aldehydes.13 Indeed, there have been few reports on the
base-catalyzed addition of dialkyl phosphites to ketones for the
Received: September 25, 2011
Published: February 7, 2012
© 2012 American Chemical Society
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synthesis of quaternary α-hydroxy phosphonates, but the yields
were not always good and mixtures of products were sometimes
obtained due to the side reactions.14 Recently, Feng and co-
workers reported the first highly efficient Lewis acid catalyzed
hydrophosphonylation of acetophenones and trifluoromethyl
15
ketones by using Ti(OiPr)4 or Et2AlCl16 as catalysts. Despite
these achievements, in view of the great utility of this
hydrophosphonylation of unactivated ketones, the development
of alternative efficient catalytic systems is still highly desirable.
To further explore the application of lanthanide complexes as
catalysts for such hydrophosphonylation of carbonyls, we
herein report the synthesis and characterization of the alkali-
metal-free bent-sandwich lanthanide amido complexes with a
Et8-calix[4]-pyrrolyl ligand, and the first application of calix[4]-
pyrrolyl-supported lanthanide amides as catalysts for hydro-
phosphonylation of aldehydes and unactivated ketones.
RESULTS AND DISCUSSION
■
Synthesis and Characterization of the Lanthanide
Amido Complexes Supported by a Calix[4]-pyrrolyl
Ligand. The lanthanide amido complexes 2−4 bearing an
Et8-calix[4]-pyrrolyl ligand were synthesized through the simple
silylamine elimination reaction, as depicted in Scheme 1. The
Figure 1. Representative structure of the lanthanide amido complexes
containing an Et8-calix[4]-pyrrolyl ligand. Hydrogen atoms are
omitted for clarity.
Table 1. Selected Bond Lengths (Å) and Bond Angles (deg)
of Complexes 2−4
Scheme 1. Preparation of the Lanthanide Amido Complexes
2−4
2 (Ln = Nd)
3 (Ln = Sm)
4 (Ln = Gd)
Ln(1)−N(1)
Ln(1)−N(2)
Ln(1)−N(3)
Ln(1)−N(1A)
Ln(1)−N(2A)
Ln(1)−C(6)
Ln(1)−C(7)
Ln(1)−C(8)
2.768(2)
2.767(3)
2.311(3)
2.680(2)
2.695(2)
2.895(3)
2.984(3)
2.973(3)
2.880(3)
2.881(3)
2.967(3)
2.960(3)
2.877(3)
103.45(8)
178.44(8)
2.737(2)
2.738(3)
2.291(3)
2.659(3)
2.676(2)
2.870(3)
2.969(3)
2.957(3)
2.854(3)
2.867(3)
2.946(3)
2.940(3)
2.858(3)
103.35(8)
178.36(8)
2.712(3)
2.708(3)
2.266(3)
2.634(3)
2.653(3)
2.861(3)
2.970(3)
2.955(4)
2.843(3)
2.845(3)
2.941(4)
2.933(3)
2.836(3)
103.73(8)
178.16(8)
Ln(1)−C(9)
Ln(1)−C(16)
Ln(1)−C(17)
Ln(1)−C(18)
Ln(1)−C(19)
N(1A)−Ln(1)−N(2A)
N(3)−Ln(1)−Ln(1A)
are bonded to the lanthanide ion in η5:η1:η5:η1-binding modes.
Each lanthanide ion adopts a distorted trigonal-bipyramidal
geometry with a N(SiMe3)2 and four pyrrolyls, in which two
opposite pyrrole rings coordinate to one lanthanide ion in η5
modes, and the nitrogen atoms of other two pyrrolyl rings bond
to another lanthanide ion in η1 modes.
reactions of the calix[4]-pyrrole [Et2C(C4H2NH)]4 (1) with 2
equiv of [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 in toluene at 110 °C
afforded the alkali-metal-free bent-sandwich lanthanide amido
bridged lanthanide amido complexes (η5:η1:η5:η1-Et8-calix[4]-
pyrrolyl){LnN(SiMe3)2}2 (Ln = Nd (2), Sm (3), Gd (4))
(Scheme 1). The complexes are sensitive to air and moisture,
and they have a good solubility in either polar solvents or
nonpolar solvents. The complexes were fully characterized by
elemental, spectroscopic, and single-crystal X-ray analyses.
X-ray analyses reveal that complexes 2−4 are isostructural
centrosymmetric dinuclear structures, and a representative
structure diagram is shown in Figure 1. The selected bond
lengths and angles are listed in Table 1. The characteristic
feature of structures in these complexes is that the bent-
sandwich lanthanide amides formed a bridge, similar to ansa-
cyclopentadienyl ligand supported lanthanide amides with
respect to each metal center. The calix[4]-pyrrolyl tetra-anions
The average distance between lanthanide ions with the five-
membered pyrrolyl ring of 2.895(3) Å in complex 2 is slightly
longer than the corresponding values of 2.874(3) and 2.860(4)
Å found in 3 and 4, respectively, due to reflection of lanthanide
contraction from Nd3+ to Sm3+ to Gd3+. The average distance
between neodymium ions and the five-membered pyrrolyl ring
of 2.895(3) Å in complex 2 is compared with those of 2.895(3)
5
Å in (η5:η1:η5:η1-Me8-calix[4]-pyrrole){DyN(SiMe3)2}2 and
2.898(3) Å in {η5:η1:η5:η1-(CH2)5C(C4H2N)}4{NdN-
(SiMe3)2}2.5 The bond distances between samarium ions and
the five-membered pyrrolyl ring ranging from 2.737(3) to
2.969(3) Å in complex 2 is comparable to the corresponding
values in ate samarium complexes (Et8-calix[4]-pyrrole)-
Sm2{(μ-Cl)2[Li(THF)2]}2 [2.860(3)−2.967(3) Å]3b and
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a
Table 2. Optimizations of Hydrophosphonylation of Benzaldehyde Catalyzed by the Lanthanide Amido Complexes
b
entry
cat. (mol %)
solvent
THF
yield (%)
1
2
3
4
5
6
7
8
9
3 (0.1 mol %)
3 (0.1 mol %)
3 (0.1 mol %)
3 (0.1 mol %)
3 (0.1 mol %)
3 (0.1 mol %)
3 (0.05 mol %)
2 (0.1 mol %)
4 (0.1 mol %)
98
92
95
94
66
81
39
97
98
toluene
Et2O
n-hexane
CH2Cl2
solvent-free
THF
THF
THF
a
b
Reaction conditions: benzaldehyde (10.0 mmol), diethyl phosphite (12.0 mmol), solvent (2 mL), room temperature. Isolated yields.
a
Table 3. Hydrophosphonylation of Aldehydes Catalyzed by the Catalyst 3
b
entry
R
product
yield (%)
1
2
Ph
6a
6b
6c
6d
6e
6f
98
99
92
98
98
93
93
94
94
97
88
83
98
71
94
94
95
93
95
92
4-MePh
3
2-MeOPh
3-MeOPh
4-MeOPh
4-BrPh
4
5
6
7
3-ClPh
6g
6h
6i
8
4-ClPh
9
2,4-Cl2Ph
2-O2NPh
3-F3CPh
pyridin-2-yl
pyridin-3-yl
thiophen-2-yl
thiophen-3-yl
furan-2-yl
n-Pr
10
11
12
13
14
15
16
17
18
19
20
6j
6k
6l
6m
6n
6o
6p
6q
6r
6s
6t
i-Pr
n-Bu
CH3(CH2)4
a
Reaction conditions: aldehyde (10.0 mmol), diethyl phosphite (12.0 mmol), catalyst (0.1 mol %), solvent: THF (2 mL), room temperature.
Isolated yields.
b
(Et8-calix[4]-pyrrole)Sm2{(μ-CH3)2[Li(THF)2]}2 [2.885(4)−
2.974(4) Å].3b The average distance between samarium ions
and the five-membered pyrrolyl ring of 2.874(3) Å in 3 is
slightly shorter than the corresponding values of 2.905(3) Å in
N-methylpyrrolyl samarium amido complexes in which the
samarium ion is coordinated by the neutral N-methylpyrrole
units in η5 modes.13 The σ-bonded Ln−N distances in
complexes 2−4, ranging from 2.266(5) to 2.311(3) Å, are
obviously shorter than the η5- and η1-bonded Ln−N distances
of 2.634(3)−2.768(3) Å in complexes 2−4, respectively. The σ-
bonded Ln−N distance of 2.291(3) Å in complex 3 is
comparable to the corresponding values of 2.265(3) Å in {(μ-
178.16° to 178.44° indicated that the two central metal ions
and two nitrogen atoms of N(SiMe3)2 are almost in the linear
form.
Addition of Diethyl Phosphite to Aldehydes Cata-
lyzed by the Lanthanide Amido Complexes Containing
a Calix[4]-pyrrolyl Ligand. The addition reaction of diethyl
phosphite with benzaldehyde was first investigated in the
presence of the lanthanide amido complexes 2−4, and the
results are summarized in Table 2. After optimizing the reaction
conditions, we were pleased to find that the reaction of diethyl
phosphite to benzaldehyde all gave the corresponding product
6a in high yields (≥92%) in the presence of 0.1 mol % of the
samarium amide in the different solvents except for CH2Cl2
(Table 2, entries 1−5), indicating the solvents’ effects on the
reaction. However, the product yield could be decreased from
17
η5:η1):η1-2-[(2,4,6-Me3C6H2)NCH2]C4H3N]SmN(SiMe3)2}2
and 2.264(4) Å in (EBI)SmN(SiMe3)2.18 The angles of two
lanthanide ions and nitrogens of N(SiMe3)2 ranging from
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a
Table 4. Optimizations of Catalytical Hydrophosphonylation of Acetophenone
b
entry
cat (mol %)
solvent
yield (%)
1
2
2 (1%)
THF
91
91
91
91
39
42
90
88
91
89
91
<5
70
2 (0.5%)
2 (0.2%)
2 (0.1%)
2 (0.05%)
2 (0.05%)
2 (0.1%)
2 (0.1%)
2 (0.1%)
3 (0.1%)
4 (0.1%)
THF
3
THF
4
THF
5
THF
6
toluene
toluene
n-hexane
Et2O
7
8
9
10
11
12
13
THF
THF
[(Me3Si)2N]3Sm(μ-Cl)Li(THF)3 (0.1%)
[(Me3Si)2N]3Sm(μ-Cl)Li(THF)3 (1%)
THF
THF
a
b
Reaction conditions: acetophenone (10.0 mmol), phosphite (12.0 mmol), solvent (2 mL), room temperature. Isolated yields.
98% to 39% by lowering the catalytic loading from 0.1 to 0.05
mol % (Table 2, entry 7). It should be noted that the LnIII ionic
radii in the complexes had little effect on the catalytic activity
on the hydrophosphonylation of benzaldehyde, and all of
complexes gave the product 6a in excellent yields (Table 2,
entries 8 and 9).
solvent indicated that the catalyst was compatible with a variety
of solvents, such as toluene, n-hexane, and diethyl ether, and
high yields of the product (>88% yield, Table 4, entries 4, 7−9)
were obtained using the neodymium amide 2 as a catalyst,
indicating the solvent compatibility of the catalyst. Therefore,
we selected a catalyst loading of 0.1 mol % in THF for the
following reactions. Examination of the catalytic activity of the
different lanthanide amides on hydrophosphonylation of
ketones also showed that high yields of product were obtained
in the presence of different catalysts, indicating that the ionic
radii of the lanthanide metals have little influence on the
catalytic activity on the hydrophosphonylation of acetophe-
none. Notably, a control experiment revealed that
[(Me3Si)2N]3Sm(μ-Cl)Li(THF)3 as the catalyst displayed
poor catalytic activity under the same reaction conditions
(Table 4, entries 12 and 13), suggesting the ligands' and
bimetal center's effect on the catalytic activity for hydro-
phosphonylation of acetophenone.
The substrate scope of catalytic hydrophosphonylation of
unactivated ketones was then investigated using the neo-
dymium amide 2 as a catalyst in THF at room temperature, and
the results are presented in Table 5. We found that the
electronic nature of the substituents on the aryl groups had
some effect on the reactivity of hydrophosphonylation of
ketones. When the substituents on the phenyl ring are the
electron-withdrawing ones, such as O2N−, Cl−, Br−, F−,
F3C−, and Ph−, the products 8b−8j can be isolated in good to
high yields (Table 5, entries 2−10). While the substituents on
the phenyl ring are the electron-donating groups, such as
CH3O− and CH3−, moderate yields of the compounds 8k−8m
(Table 5, entries 11−13) were achieved after 2 h. It was also
found that the steric hindrance of the substrates had an
significant effect on the reactivity of the hydrophosphonylation
of ketones; for example, the addition of diethyl phosphite to 4′-
bromoacetophenone gave the product 8g in 95% yield for only
20 min (Table 5, entry 7), whereas the addition of diethyl
phosphite to 2′-bromoacetophenone gave the product in only
79% yield even in 2 h (Table 5, entry 6). Similarly, 4′-
methylacetophenone was converted to the corresponding
product 8l in 76% yield (Table 5, entry 12), whereas 2′-
methylacetophenone gave the product 8k in only 41% yield
Under the optimized reaction conditions, we next examined
the substrate scope of the hydrophosphonylation reaction in
the presence of the samarium amide 3 (0.1 mol %) in THF
(Table 3). The results showed that the addition of diethyl
phosphite to a variety of aromatic aldehydes afforded the
corresponding α-hydroxy phosphonates in excellent yields of
≥88%, regardless of the electronic nature or the steric effects of
the substituents on the aryl groups (Table 3, entries 1−9).
Heteroaromatic aldehydes, such as pyridine-2-carboxaldehyde,
pyridine-3-carboxaldehyde, thiophene-2-carboxaldehyde, thio-
phene-3-carboxaldehyde, and 2-furaldehyde, also worked well,
and the α-hydroxy phosphonates 6j−6n were obtained in good
to excellent yields (Table 3, entries 10−14). Interestingly, both
linear and branched aliphatic aldehydes were also efficiently
used as the substrates in the presence of the catalyst 3 to afford
the corresponding α-hydroxy phosphonates in high yields
(Table 3, entries 15−18).
Addition of Diethyl Phosphite to Ketones Catalyzed
by the Lanthanide Amido Complexes Containing a
Calix[4]-pyrrolyl Ligand. To further investigate the scope of
the application for the hydrophosphonylation reaction, we paid
attention to a more challenging system, that is, the lanthanide
amide catalyzed reaction of unactivated ketones with dialkyl
phosphate. To obtain the good result, various reaction
conditions for the addition of diethyl phosphite to
acetophenone were examined in the presence of calix[4]-
pyrrolyl lanthanide amido complexes, and the results are
summarized in Table 4. The reaction of diethyl phosphite with
acetophenone in the presence of 1−0.1 mol % of the
neodymium amide 2 was carried out, respectively. To our
delight, in all cases, the desired product 8 was obtained in high
yields (up to 91%) (Table 4, entries 1−4). While the catalyst
loading was reduced from 0.1 to 0.05 mol %, the yields of the
product decreased dramatically from 91% to 39% (Table 4,
entries 5 and 6). Next, investigations for the choice of the
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ab
,
Table 5. Hydrophosphonylation of Ketones Catalyzed by the Calix[4]-pyrrolyl Amido Neodymium Complex
a
b
Reaction conditions: ketone (10.0 mmol), phosphite (12.0 mmol), catalyst 2 (0.1 mol %), THF (2 mL), room temperature. Isolated yields.
after 2 h (Table 5, entry 11). A heteroaromatic ketone, such as
4-acetylpyridine, was also efficiently used as the substrate under
the optimal reaction conditions to form the α-hydroxy
phosphonate 8n in an excellent yield (Table 5, entry 14).
Interestingly, an excellent yield of 8o was achieved when
benzophenone was treated with diethyl phosphate employing
the neodymium amide 2 as a catalyst (Table 5, entry 15). It
should be noted that the catalyst 2 also worked well for both
linear and branched aliphatic ketones, affording the correspond-
ing α-hydroxy phosphonates in high yields (Table 3, entries 16
and 17). Furthermore, nonmethyl ketones, such as 3-pentanone
and cyclohexanone, were also applicable to this reaction, and
the reaction afforded corresponding α-hydroxy phosphonates
8r and 8s in 94% and 90% yields, respectively (Table 3, entries
18 and 19).
CONCLUSIONS
■
In summary, the dinuclear trivalent lanthanide amido
complexes bearing a tetra-anion calix[4]-pyrrolyl ligand were
synthesized by the simple silylamine elimination reaction of
calix[4]-pyrrole with the lanthanide amides [(Me3Si)2N]3Ln(μ-
Cl)Li(THF)3. The X-ray diffraction analyses discovered that
the key features of the structures of these complexes were that
the bent-sandwich lanthanide amido formed a bridge, similar to
ansa-cyclopentadienyl ligand supported lanthanide amides with
respect to each metal center and that the two pyrrolyl rings in
each metal center took the eclipsed form. All of these
lanthanide amido complexes displayed high catalytic activities
for hydrophosphonylation of aldehydes and unactivated
ketones. The addition of diethyl phosphite to aldehydes and
ketones afforded the products in high yields of up to 97% by
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the SHELXTL program package.22 All hydrogen atoms were refined
using a riding model. See Table6 for crystallographic data.
employing low loadings of the catalysts (0.1 mol %) at room
temperature in a very short time (20 min). The catalysts are
suitable for a series of organic solvents and work well for a wide
range of aliphatic, aromatic, and heteroaromatic aldehydes and
ketones. The results highlight the first application of calix[4]-
pyrrolyl-supported lanthanide amides as catalysts for hydro-
phosphonylation of unactivated ketones. Further investigations
of new catalytic systems for hydrophosphonylation of
unactivated ketones are in progress.
Table 6. Crystallographic Data for the Complexes 2−4
2
3
4
formula
formula wt
cryst syst
space group
a (Å)
C48H84Nd2N6Si4
1146.05
C48H84Sm2N6Si4
1158.27
monoclinic
C2/c
C48H84Gd2N6Si4
1172.07
monoclinic
C2/c
monoclinic
C2/c
18.6562(12)
14.4656(9)
21.5024(14)
104.4540(10)
5619.2(6)
293(2)
18.6547(11)
14.4585(8)
21.4286(12)
104.2550(10)
5601.7(6)
293(2)
18.6298(14)
14.4462(11)
21.3833(16)
104.0420(10)
5582.9(7)
293(2)
EXPERIMENTAL SECTION
■
b (Å)
General Remarks. All syntheses and manipulations of air- and
moisture-sensitive materials were performed under dry argon and a
oxygen-free atmosphere using standard Schlenk techniques or in a
glovebox. All solvents were refluxed and distilled over sodium
benzophenone ketyl under argon prior to use unless otherwise
noted. Solid aldehydes and ketones were directly used, and liquid
aldehydes and ketones were distilled before use. [(Me3Si)2N]3Ln(μ-
c (Å)
β (deg)
V (Å3)
T (K)
Z
4
4
4
Dcalcd (g cm−3
)
1.355
1.373
1.394
19
20
μ (mm−1
)
1.948
2.197
2.476
Cl)Li(THF)3 and [Et2C(C4H2NH)]4 were prepared according to
literature methods. IR spectra were recorded on a SHIMADZU FTIR-
8400S spectrometer. 1H NMR, 13C NMR, and 31P NMR spectra were
recorded on a Bruker AV-300 NMR spectrometer in CDCl3. The
chemical shifts are reported in parts per million relative to the internal
standard TMS (1H NMR), to residual signals of the solvents (CHCl3,
77.0 ppm for 13C NMR) and to the external standard 85% H3PO4 (31P
NMR).
F(000)
2360
2376
2392
θ range (deg)
1.80−27.58
1.80−27.56
23 979
1.80−27.64
23 561
reflns collected 23 988
unique reflns
parameters
6454
6450
6493
(Rint = 0.0221)
(Rint = 0.0261)
282
(Rint = 0.0258)
282
282
Synthesis of (η5:η1:η5:η1-Et8-Calix[4]-pyrrole){NdN(SiMe3)2}2
(2). To a toluene (30.0 mL) solution of [(Me3Si)2N]3Nd(μ-
Cl)Li(THF)3 (0.958 g, 1.08 mol) was added a toluene (10.0 mL)
solution of ligand 1 (0.293 g, 0.54 mmol) at room temperature. After
the reaction mixture was stirred at room temperature for 6 h, the
mixture was stirred at 110 °C for 24 h. The solvent was evaporated
under reduced pressure. The residue was extracted with n-hexane (2 ×
10.0 mL). The extractions were combined and concentrated to about
10.0 mL. Pale blue crystals were obtained by recrystallization from the
concentrated n-hexane solution at 0 °C (0.327 g, 57% yield). mp 263
°C. IR (KBr pellets): ν 3437 (s), 2963 (s), 2934 (s), 2874 (m), 1574
(m), 1501 (m), 1458 (m), 1414 (m), 1379 (m), 1331 (w), 1281 (w),
1198 (m), 1182 (m), 1051 (m), 932 (m), 841(m), 762 (s) cm−1. Anal.
Calcd for C48H84N6Si4Nd2: C, 50.30; H, 7.39; N, 7.33. Found: C,
49.88; H, 7.23; N, 7.02.
goodness of fit 1.151
1.026
1.100
R1 (I > 2σ(I)) 0.0281
0.0274
0.0285
wR2 (I >
2σ(I))
0.0717
0.0667
0.0714
largest diff.
peak and
0.984 and −0.857 0.800 and −0.614 0.860 and −0.952
hole (e·Å−3
)
General Procedures for Hydrophosphonylation of Alde-
hydes. A 30.0 mL Schlenk tube under dried argon was charged with
the calix[4]-pyrrolyl lanthanide amido complex 3 (11.6 mg, 0.01
mmol), diethyl phosphite (1.66 g, 12 mmol), and THF (2.0 mL); then
aldehyde (10.0 mmol) was added to the mixture. The resulting
mixture was allowed to stir at room temperature for 20 min. After the
reaction was completed, the reaction mixture was hydrolyzed by water
(3.0 mL), extracted with ethyl acetate (3 × 10.0 mL), dried over
anhydrous Na2SO4, and filtered. After the solvent was removed under
the reduced pressure, the final products were further purified by
washing with hexane. The characterization data for the resulting
products can be read in the Supporting Information.
General Procedures for Hydrophosphonylation of Ketones.
A 30.0 mL Schlenk tube under dried argon was charged with the
calix[4]-pyrrolyl lanthanide amido complex 2 (11.5 mg, 0.01 mmol),
diethyl phosphite (1.66 g, 12 mmol), and THF (2.0 mL); then ketone
(10.0 mmol) was added to the mixture. The resulting mixture was
allowed to stir at room temperature for 20 min. After the reaction was
completed, the reaction mixture was hydrolyzed by water (3.0 mL),
extracted with ethyl acetate (3 × 10.0 mL), dried over anhydrous
Na2SO4, and filtered. After the solvent was removed under the reduced
pressure, the final products were further purified by washing with
hexane. The characterization data for the resulting products can be
read in the Supporting Information.
Synthesis of (η5:η1:η5:η1-Et8-Calix[4]-pyrrole){SmN(SiMe3)2}2
(3). Complex 3 was prepared as yellow crystals in 52% yield from
the reaction of compound 1 (0.277 g, 0.51 mmol) with
[(Me3Si)2N]3Sm(μ-Cl)Li(THF)3 (0.912 g, 1.02 mol) by employing
the procedures similar to those used for the preparation of 2. mp 259
°C. IR (KBr pellets): ν 3437 (s), 2965 (s), 2931 (s), 2876 (m), 1574
(m), 1500 (m), 1461 (m), 1414 (m), 1379 (m), 1332 (m), 1280 (w),
1198 (m), 1182 (m), 1051 (m), 933 (m), 841 (m), 763 (s) cm−1.
Anal. Calcd for C48H84N6Si4Sm2: C, 49.77; H, 7.31; N, 7.26. Found: C,
49.62; H, 7.07; N, 7.14.
Synthesis of (η5:η1:η5:η1-Et8-Calix[4]-pyrrole){GdN(SiMe3)2}2
(4). Complex 4 was prepared as colorless crystals in 53% yield from
the reaction of compound 1 (0.283 g, 0.52 mmol) with
[(Me3Si)2N]3Gd(μ-Cl)Li(THF)3 (0.933 g, 1.04 mol) by employing
the procedures similar to those used for preparation of 2. mp 261 °C.
IR (KBr pellets): ν 3437 (s), 2965 (s), 2932 (s), 2873 (m), 1574 (m),
1500 (m), 1458 (m), 1414 (m), 1377 (m), 1331 (m), 1281 (w),
1252(m), 1198 (m), 1099 (w), 1051 (m), 926 (m), 841 (m), 762
(s),706 (s) cm−1. Anal. Calcd for C40H68N6Si4Gd2: C, 49.19; H, 7.22;
N, 7.17. Found: C, 49.42; H, 7.08; N, 6.98.
Crystal Structure Determinations. Suitable crystal of complexes
2−4 was each mounted in a sealed capillary. Diffraction was performed
on a Burker SMART CCD area detector diffractometer using graphite-
monochromated Mo Kα radiation (λ = 0.71073 Å). An empirical
absorption correction was applied using the SADABS program.21 All
structures were solved by direct methods, completed by subsequent
difference Fourier syntheses, refined anisotropically for all non-
hydrogen atoms by full-matrix least-squares calculations on F2 using
ASSOCIATED CONTENT
■
S
* Supporting Information
The characterization data for α-hydroxy phosphonates and X-
ray crystallographic files, in CIF format, for structure
determination of complexes 2−4. This material is available
free of charge via the Internet at http://pubs.acs.org.
1701
dx.doi.org/10.1021/om2008925 | Organometallics 2012, 31, 1696−1702

Organometallics
Article
Zhao, D.; Lan, J.; Xi, P.; Yang, L.; Xiang, S.; You, J. Angew. Chem., Int.
Ed. 2008, 47, 5646−5649. (d) Jung, M. E.; Cordova, J.; Murakami, M.
Org. Lett. 2009, 11, 3882.
AUTHOR INFORMATION
Corresponding Author
*Fax: (86)553-3883517. Tel: (86)553-5910015. E-mail:
swwang@mail.ahnu.edu.cn (S.W.), zljun@mail.ahnu.edu.cn
(L.Z.).
■
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Financial support for this work from the National Natural
Science Foundation of China (20832001, 20802001, 21072004,
21172004), the National Basic Research Program of China
(2012CB821604), and grants from the Ministry of Education
(20103424110001), Anhui province (11040606M36), are
acknowledged.
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