Half-sandwich o-N,N-dimethylaminobenzyl complexes over the full size range of group 3 and lanthanide metals. synthesis, structural characterization, and catalysis of phosphine P-H bond addition to carbodiimides

Article abstract of DOI:10.1002/chem.200701300

The acid-base reactions between the rare-earth metal (Ln) tris(ortho-N,N-dimethylaminobenzyl) complexes [Ln(CH₂C ₆H₄NMe₂-o)₃] with one equivalent of the silylene-linked cyclopentadiene-amine ligand (C

Full text of DOI:10.1002/chem.200701300

FULL PAPER
DOI: 10.1002/chem.200701300
Half-Sandwich o-N,N-Dimethylaminobenzyl Complexes over the Full Size
Range of Group 3 and Lanthanide Metals. Synthesis, Structural
À
Characterization, and Catalysis of Phosphine P H Bond Addition to
Carbodiimides
Wen-Xiong Zhang, Masayoshi Nishiura, Tomohiro Mashiko, and Zhaomin Hou*[a]
À
Abstract: The acid-base reactions be-
tween the rare-earth metal (Ln) tris-
alytic addition of various phosphine P
H bonds to carbodiimides to form a
series of phosphaguanidine derivatives
with excellent tolerability to aromatic
carbon-halogen bonds. A significant in-
crease in the catalytic activity was ob-
served, as a result of an increase in the
metal size with a general trend of La>
Pr, Nd>Sm>Gd>Lu>Sc. The reac-
tion of 2-La with 1 equiv of Ph2PH
yielded the corresponding phosphide
2,4,6)}La
G
G
U
which, on recrystallization from ether,
afforded the ether-coordinated struc-
A
plexes [Ln(CH2C6H4NMe2-o)3] with
one equivalent of the silylene-linked
cyclopentadiene-amine ligand (C5Me4H)-
turally
[{Me2Si
{iPrNC(PPh2)NiPr}
characterizable
(C5Me4)(NC6H2Me3-2,4,6)}La-
(OEt2)] (7). The re-
analogue
A
G
N
ACHTREUNG
A
action of 6 or 7 with Ph2PH in THF
yielded 4 and the phosphaguanidine
E
iPrN=C(PPh2)NHiPr (3a). These re-
R
A
sults suggest that the catalytic forma-
tion of a phosphaguanidine compound
proceeds through the nucleophilic ad-
dition of a phosphide species, which is
formed by the acid-base reaction be-
tween a rare-earth metal o-dimethyl-
aminobenzyl bond and a phosphine
ACHTREUNG
Gd, Lu) in 60–87% isolated yields. The
one-pot reaction between ScCl3 and
complex [{Me2Si
2,4,6)}La(PPh2)(thf)2] (4), which, on re-
crystallization from benzene, gave the
dimeric analogue [{Me2Si(C5Me4)-
(NC6H2Me3-2,4,6)}La(PPh2)]2 (5). Ad-
(C5Me4)(NC6H2Me3-
A
ACHTREUNG
[Me2Si
followed
LiCH2C6H4NMe2-o in THF gave the
scandium analogue [{Me2Si(C5Me4)-
(NC6H2Me3-2,4,6)}Sc(CH2C6H4NMe2-o)]
A
N
ACHTREUNG
AHCTREUNG
A
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À
T
dition of 4 or 5 to iPrN=C=NiPr in
THF yielded the phosphaguanidinate
P H bond, to a carbodiimide, followed
N
N
N
R
G
N
T
C
A
by the proton
(2-Sc) in 67% isolated yield. 2-Sc could
not be prepared by the acid-base reac-
tion between [Sc(CH2C6H4NMe2-o)3]
and (C5Me4H)SiMe2NH(C6H2Me3-2,4,6).
These half-sandwich rare-earth metal
aminobenzyl complexes can serve as
efficient catalyst precursors for the cat-
complex [{Me2Si
G
U
phosphaguanidinate species by a phos-
À
phine P H bond. Almost all of the
rare earth complexes reported this
paper were structurally characterized
by X-ray diffraction studies.
Keywords: carbodiimides · homo-
geneous catalysis · P H bond acti-
vation · phosphaguanidines · phos-
phorus · rare-earth metals
Introduction
Rare earth (group 3 and lanthanide) metal alkyl complexes
are an important class of organometallic compounds, which
can show novel activity in various stoichiometric and cata-
lytic processes.[1,2] Rare-earth metal alkyl complexes bearing
the silylene-linked cyclopentadienyl-amido ligand have
drawn considerable attention, because they are electronical-
ly less saturated and sterically more accessible than the ordi-
nary metallocene analogues that have two cyclopentadienyl
ancillary ligands.[2] The first silylene-linked cyclopentadien-
[a] Dr. W.-X. Zhang, Dr. M. Nishiura, T. Mashiko, Prof. Dr. Z. Hou
Organometallic Chemistry Laboratory
RIKEN, The Institute of Physical and Chemical Research
Hirosawa 2–1, Wako, Saitama 351-0198 (Japan)
Fax : (+81)48-462-4665
E-mail: houz@riken.jp
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
Chem. Eur. J. 2008, 14, 2167 – 2179
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2167

yl-amido rare-earth metal alkyl complex [{Me2Si
(NtBu)}Sc{CH(SiMe3)2}] was reported in the early 1990s by
Bercaw et al., which was obtained by salt metathesis be-
tween the scandium chloride complex [{Me2Si(C5Me4)-
(NtBu)}ScCl] and LiCH
(SiMe3)2.[3] It was later found by
C
synthesis and as unique ligands for various metal com-
plexes[9]—such a catalytic process remained scarce.[10]
We recently found that half-sandwich rare-earth metal
G
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(trimethylsilyl)methyl complexes such as [{Me2Si
(NR)}Y(CH2SiMe3)(thf)x] (R=Ph, C6H2Me3-2,4,6, tBu)
could serve as efficient catalysts for the catalytic addition of
A
N
U
A
N
ACHTREUNG
Okuda and our group that the acid-base reactions between
the rare-earth metal tris(trimethylsilyl)methyl complexes
À
À
terminal alkyne C H and amine N H bonds to carbodi-
[Ln(CH2SiMe3)3
A
A
ene-linked cyclopenetadiene-amine ligands (C5Me4H)
SiMe2NHR (R=alkyl, aryl) can offer an excellent salt-free
route to the corresponding half-sandwich alkyl com-
plexes.[4,5] Marks and coworkers found that the similar acid-
guanidines,[5c,e] respectively. We wish to report here that
such half-sandwich rare-earth metal complexes can also cat-
À
alyze the addition of phosphine P H bonds to carbodiimides
to afford the corresponding phosphaguanidines. Moreover,
by using ortho-dimethylaminobenzyl CH2C6H4NMe2-o in-
stead of (trimethylsilyl)methyl CH2SiMe3 as an alkyl ligand,
we have successfully synthesized and structurally character-
ized the corresponding half-sandwich complexes over the
full size range of the rare-earth metal series (Sc, Y, La, Pr,
Nd, Sm, Gd, and Lu). Significant effects of the metal ion
size on the catalytic activity of these complexes in the cata-
base
methylsilyl)methyl} complexes [Ln{CH
and Lu) and the neutral ligand (C5Me4H)
reaction
between
the
bulkier
(SiMe3)2}3] (Ln=Yb
Me2SiNHtBu
tris
{bis
(tri-
A
ACHTREUNG
AHCTREUNG
could also afford the corresponding analogues, albeit under
forcing conditions.[6] Harder and Carpentier reported that
the synthesis of yttrium aminobenzyl and alkyl complexes
bearing the silylene-linked fluorenyl-amido ligands, such as
À
[{Me2Si
[{Me2Si(h3-3,6-tBu2C13H6)
be achieved by the acid-base reaction of the tris(aminoben-
zyl) and tris(alkyl) precursors such as [Y(CH2C6H4NMe2-
o)3] and [Y(CH2SiMe3)3(thf)2] with the corresponding fluo-
rene-amine ligands. We recently found that the reaction of
the scandium tris(aminobenzyl) complex [Sc-
(CH2C6H4NMe2-o)3] with C5Me4(SiMe3)H can afford the
corresponding half-sandwich bis(aminobenzyl) complex
[(C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2], which can serve as a
A
E
A
N
lytic addition of phosphine P H bonds to carbodiimides
G
G
E
were observed. Typical phosphide and phosphaguanidinate
reaction intermediates were isolated and their reactivity was
also investigated, which offers strong evidence for the un-
derstanding of the mechanistic aspects of this catalytic pro-
cess.
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A
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A
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Results and Discussion
A
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novel catalyst precursor for the polymerization and copoly-
merization of various olefins.[8] Despite these extensive stud-
ies in this area, the rare-earth metal half-sandwich alkyl
complexes reported so far in the literature have been limit-
ed solely to those of relatively small metals (such as Sc, Y,
Yb, and Lu), whereas complexes that contain larger metal
ions (ranging from La to Gd) remained unknown. Previous
attempts to synthesize a samarium half-sandwich alkyl com-
Synthesis and structural characterization of rare-earth metal
o-dimethylaminobenzyl complexes bearing silylene-linked
cyclopentadienyl-amido ligands: Similar to the synthesis of
the half-sandwich (trimethylsilyl)methyl complex [{Me2Si-
A
N
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A
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easily prepared by the reaction of [Y(CH2C6H4NMe2-o)3]
with 1 equivalent of (C5Me4H)SiMe2NH(C6H2Me3-2,4,6), as
shown in Scheme 1. More remarkably, such half-sandwich
aminobenzyl complexes 2-Ln (Ln=La, Pr, Nd, Sm, Gd, and
Lu) could be obtained over the whole size range of the lan-
thanide series in the same manner (Scheme 1). However, an
attempt to make the analogous Sc complex by the reaction
plex by reaction of [Sm{CH
Me2SiNHtBu at high temperatures were unsuccessful, as a
result of the thermal instability of the tris(alkyl) samarium
(SiMe3)2}3] with (C5Me4H)-
ACHTREUNG
AHCTREUNG
complex.[6] The reactivity of rare-earth metal complexes is
usually greatly influenced by the ion size of the central
metals. Therefore, synthesis of half-sandwich rare-earth
metal alkyl complexes over the full size range of this series
of metals is of much interest and importance.
On the other hand, although the nucleophilic addition of
main group metal phosphides “R’2PM” to carbodiimides
RN=C=NR is a well-known method for the preparation of
the
[RNC
corresponding
phosphaguanidinate
complexes
“
A
ACHTREUNG
phosphides with carbodiimides has not been reported previ-
À
ously. Although catalytic addition of phosphine P H bonds
across the C=N bond of carbodiimides could be an efficient
method for the synthesis of phosphaguanidines [RN=C-
ACHTREUNG
Scheme 1. Synthesis of half-sandwich o-dimethylaminobenzyl complexes
of La, Pr, Nd, Sm, Gd, Lu, and Y.
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Chem. Eur. J. 2008, 14, 2167 – 2179

Rare-Earth Metal Catalyst Precursors
FULL PAPER
of
[Sc(CH2C6H4NMe2-o)3]
with
(C5Me4H)SiMe2NH-
G
N
ACHTREUNG
much smaller size of the Sc ion, which could render the
metal center too crowded to result in a reaction between
the aminobenzyl unit and the bulky cyclopentadiene-amine
ligand. Alternatively, the metathetical reaction between
ScCl3 and [Me2Si(C5Me4)(NC6H2Me3-2,4,6)]Li2 followed by
G
addition of LiCH2C6H4-NMe2-o in THF, afforded the corre-
sponding half-sandwich scandium aminobenzyl complex
[{Me2Si
N
N
Sc) in 67% isolated yield (Scheme 2).
Figure 1. ORTEP drawing of 2-La with 30% thermal ellipsoids. Hydro-
gen atoms are omitted for clarity.
Scheme 2. Synthesis of a half-sandwich scandium o-dimethylaminobenzyl
complex.
All of these aminobenzyl complexes 2-Ln, were structur-
ally characterized by X-ray diffraction analyses. Their select-
ed bond lengths and angles are summarized in Table 1, and
the ORTEP drawings of 2-La, 2-Lu, and 2-Sc are shown in
Figures 1–3, respectively. The complexes of Ln=Y, La, Pr,
Nd, Sm, Gd, and Lu contain a THF-coordination ligand,
while the smallest Sc complex is THF-free, reflecting the dif-
ference in ion size between Sc and other larger metals. All
these complexes adopt a similar overall structure. The o-di-
methylaminobenzyl group is bonded to the metal center in a
chelating fashion through both the benzyl unit and the
amino group. The cyclopentadienyl group adopts an h5-coor-
dinate mode in all of these complexes, in contrast with the
Figure 2. ORTEP drawing of 2-Lu with 30% thermal ellipsoids. Hydro-
gen atoms are omitted for clarity.
fluorenyl-ligated yttrium analogue [{Me2Si
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A
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ligand showed an h3-coordinate fashion.[7a] Almost all the
bond distances around the metal centers decreased as the
metal size decreased in the order of La>Pr>Nd>Sm>
by the fact that although Lu is smaller than Gd and Y, they
all have the same coordination number.[11] These data may
suggest that the interaction between the metal center and
À
Gd>Y>Lu>Sc (Table 1). The Lu N (amino-group) bond
(2.714(4) Š), however, is exceptionally longer than the
the dimethylamino group in 2-Lu is weaker than that in
G
other larger metal complexes, probably because Lu is a little
too small to keep the same coordination number as other
larger metals do.
À
Gd N(amino-group)
À
bond
(2.707(7) Š)
and
the
Y N(amino-group) bond (2.690(2) Š), this can be explained
Table 1. Selected bond lengths [Š] and angles [8] for 2-Ln (Ln= La, Pr, Nd, Sm, Gd, Lu, Y, and Sc).
2-La
2-Pr
2-Nd
2-Sm
2-Gd
2-Lu
2-Y
2-Sc
À
Ln N(Bz)
2.792(2)
2.416(2)
2.564(2)
2.609(3)
2.505(3)
2.782(3)
91.43(8)
98.50(11)
105.59(10)
63.01(8)
2.767(2)
2.384(2)
2.538(2)
2.564(3)
2.468(3)
2.749(3)
92.92(8)
98.49(12)
104.95(10)
64.00(8)
2.748(3)
2.357(2)
2.511(3)
2.537(3)
2.447(3)
2.728(3)
93.20(10)
97.81(13)
105.40(12)
64.14(10)
2.730(4)
2.343(4)
2.483(3)
2.503(5)
2.424(5)
2.707(5)
94.29(15)
98.3(2)
2.707(7)
2.309(6)
2.445(5)
2.486(7)
2.392(8)
2.675(8)
95.43(2)
97.8(3)
2.714(4)
2.227(4)
2.321(4)
2.337(6)
2.356(6)
2.646(6)
97.76(19)
97.9(2)
2.690(2)
2.288(2)
2.4025(19)
2.445(3)
2.369(3)
2.659(3)
96.40(9)
97.89(11)
103.89(11)
66.04(8)
2.2908(15)
2.0823(14)
–
2.2570(18)
2.2570(17)
2.4708(17)
104.36(7)
95.74(7)
102.77(7)
77.45(7)
À
Ln N(Ar)
À
Ln O
À
Ln C(Bz)
À
Ln Cp
A
À
Ln Cp(av)
À
À
aN(Ar) Ln Cp
(centroid)
À
À
aN(Ar) Si C(Cp)
À À
aSi N Ln
104.62(18)
64.84(14)
104.2(3)
65.3(2)
103.5(2)
66.97(17)
À
À
aC Ln N(Bz)
Chem. Eur. J. 2008, 14, 2167 – 2179
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2169

Z. Hou et al.
creased as the metal size becomes larger (Lu<Gd<Sm<
Nd<Pr<La) (Table 2, entries 5–10). The largest lanthanum
complex 2-La showed the highest activity. THF seemed to
be a better solvent than benzene or toluene for this reaction
(Table 2, entries 10–12). Thus, in the presence of 1 mol% of
2-La, the reaction of Ph2PH with iPrN=C=NiPr in THF at
808C yielded the corresponding phosphaguanidine 3a quan-
titatively within 1 h (Table 2, entry 13).
Table 3 summarizes some representative results of reac-
tions between various phosphines and carbodiimides cata-
lyzed by the lanthanum complex 2-La. A wide range of di-
arylphosphines could be used in this reaction. The reaction
was not affected by either electron-withdrawing or -donating
substituents, or their positions at the phenyl ring of the
Figure 3. ORTEP drawing of 2-Sc with 30% thermal ellipsoids. Hydrogen
À
atoms are omitted for clarity.
phosphines (Table 3, entries 1–10). Aromatic C Cl (entries 8
À
and 9) and C Br (entry 10) bonds survived the catalytic
conditions to yield selectively the corresponding halogen-
substituted phosphaguanidines 3i–k, which could serve as
useful building blocks for the construction of further larger
phosphaguanidine derivatives. The reaction of an alkyl/aryl
phosphine such as ethylphenylphosphine (entry 11) with
iPrN=C=NiPr required a longer time for completion, where-
as a dialkyl phosphine could not be utilized in this reaction,
probably owing to the weaker acidity of these phosphines
compared to that of diarylphosphines. The reaction of
PhPH2 with iPrN=C=NiPr afforded selectively the mono-ad-
Catalytic addition of phosphines to carbodiimides: The reac-
tion of diphenylphosphine Ph2PH with N,N’-diisopropylcar-
bodiimide iPrN=C=NiPr was first examined under various
conditions. As a control experiment, iPrN=C=NiPr was
heated with Ph2PH in C6D5Cl at 1408C for 12h, but no reac-
tion was observed (Table 2, entry 1). In contrast, addition of
a small amount of the (trimethylsilyl)methyl complex 1-Y at
808C, led to rapid addition of Ph2PH to iPrN=C=NiPr to
give the corresponding phosphaguanidine 3a in 86% yield
in 1 h (Table 2, entry 2). The aminobenzyl analogue 2-Y
showed the same activity as that of 1-Y (Table 2, entry 3),
which showed that the catalytic activity was not affected by
the alkyl group under the present conditions. The scandium
complex 2-Sc showed a significantly lower activity than that
of 2-Y under the same conditions (Table 2, entry 4). Among
the lanthanide complexes from Lu to La, the activity in-
dition product iPrN=C
N
N
most of the above reactions, the resulting phosphaguanidine
products could be isolated in excellent yields, simply by a
1
single recrystallization. The H and 13C NMR spectra of the
phosphaguanidine products 3a–n all showed only one
isomer in solution, which could be assigned as the Esyn
isomer according to literature.[12,9a–c]
Isolation and reactivity of the
lanthanum phosphide and phos-
Table 2. Catalytic addition of diphenylphosphine to N,N’-diisopropylcarbodiimide.[a]
phaguanidinate intermediates:
To gain information on the true
catalyst species and the reaction
mechanisms, the stoichiometric
reaction between 2-La and di-
phenylphosphine was first car-
ried out in THF at room tem-
perature for 5 h, which gave the
Entry
Catalyst
[mol%]
Ionic radius of
Ln3+ [Š][b]
Solvent
T
[8C]
t
Yield[c]
[%]
A
[h]
1
2
3
4
5
6
7
8
0
–
C6D5Cl
140
80
80
80
80
80
80
80
80
120
1
corresponding
phosphide complex [{Me2Si-
(C5Me4)(NC6H2Me3-2,4,6)}La-
(PPh2)(thf)2] (4) in 92% isolat-
half-sandwich
1-Y (3)
2-Y (3)
2-Sc (3)
2-Lu (3)
2-Gd (3)
2-Sm (3)
2-Nd (3)
2-Pr (3)
2-La (3)
2-La (3)
2-La (3)
2-La (1)
2-La (0.5)
0.900
0.900
0.745
0.861
0.938
0.958
0.983
0.990
1.032[D
1.032C
1.032[D
1.032[D
1.032[D
[D8]THF
[D8]THF
[D8]THF
[D8]THF
[D8]THF
[D8]THF
[D8]THF
[D8]THF
8]THF
6D6
8]toluene
8]THF
8]THF
86
86
15
50
65
69
93
94
>99
85
1
1
1
1
1
1
1
A
ACHTREUNG
A
ACHTREUNG
ed yield (Scheme 3). Complex 4
is highly soluble in THF but
sparingly soluble in n-hexane.
Recrystallization of 4 in THF/
ether at room temperature af-
forded light-yellow single crys-
tals. An X-ray analysis revealed
9
10
11
12
13
14
80
0.5
18
9
110
110
80
95
>99
1
298
80
that
4 adopts a monomeric
[a] Conditions: diphenylphosphine (0.35 mmol), N,N(-diisopropylcarbodiimide (0.34 mmol), Ln catalyst.
[b] Ionic radius of six-coordination.[11] [c] Yields were determined by 31P NMR.
structure in which the metal
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Chem. Eur. J. 2008, 14, 2167 – 2179

Rare-Earth Metal Catalyst Precursors
FULL PAPER
Table 3. Catalytic addition of phosphines to carbodiimides.[a]
meric structure through the
phosphido bridges (Figure 5).
There is no THF ligand in 5. A
crystallographic
inversion
center exists at the center of
the molecule. The phosphido
bridges are highly unsymmetri-
cal. The length of the bridging
Entry
1
R’’R’’’PH
RN=C=NR’
Product
Yield[b] [%]
Ph2PH
CyN=C=NCy
3b(99)
À
La1 P1’ bond (3.0675(13) Š) is
significantly shorter than that
À
of
the
La1 P1
bond
2Ph
2PH
EtN=C=NtBu
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
iPrN=C=NiPr
3c(95)
3d(99)
3e(99)
3f(99)
3g(98)
3h(99)
3i(97)
(3.1427(12) Š), can be com-
pared even with the terminal
La P bond found in
(3.0697(16) Š). The La Cp-
À
4
À
3
(2-MeC6H4)2PH
AHCTREUNG
4
4
(3-MeC6H4)2PH
(2.541(6) Š), probably because
the coordination number of the
La ion in 5 (six) is smaller than
that in 4 (seven). The La N
bond distances in both
(2.372(5) Š) and 5 (2.372(3) Š),
however, are almost the same.
At room temperature, the di-
À
5
(4-MeC6H4)2PH
4
6
(3,5-Me2C6H3)2PH
(4-MeOC6H4)2PH
meric structure of
5 could
remain for about 24 h in THF.
It showed a broad 31P NMR
peak at 8.53 ppm in [D8]THF,
in contrast with that of the
7
monomeric 4, which gave
a
8
(4-ClC6H4)2PH
sharp singlet at À14.5 ppm.
However, on heating in THF at
808C for 5 h, 5 was completely
converted into 4. The reaction
of 4 or 5 with iPrN=C=NiPr in
THF at room temperature gave
the phosphaguanidinate com-
9
(3,5-Cl2C6H3)2PH
3j(95)
10
(4-BrC6H4)2PH
3k(97)
3l(86)[c]
3m(96)[c]
plex
(NC6H2Me3
(PPh2)NiPr}
[{Me2Si
-2,4,6)}La{iPrNC-
(thf)] (6) in 93%
(C5Me4)-
A
N
ACHTREUNG
G
ACHTREUNG
11
PhEtPH
isolated yield (Scheme 3). Re-
crystallization of 6 in ether at
room temperature yielded the
ether-coordinated
[{Me2Si(C5Me4)(NC6H2Me3-
2,4,6)}La{iPrNC(PPh2)NiPr}-
(OEt2)] (7) as light-orange crys-
tals suitable for X-ray analysis.
crystallographic study
showed that the phosphaguani-
complex
12PhPH
2
AHCTREUNG
A
ACHTREUNG
[a] Conditions: phosphine (2.02 mmol), carbodiimide (2.00 mmol), catalyst (0.02 mmol), solvent (5 mL).
[b] Isolated yield. [c] Toluene, 1108C, 12h.
AHCTREUNG
A
center is bonded to one Cp’-amido ligand, one PPh2 ligand,
and two THF ligands (Figure 4). When 4 was recrystallized
in benzene, light yellow single crystals of [{Me2Si-
dinate unit in 7 is bonded to the metal center through the
two N atoms, as observed in a normal guanidinate or amidi-
À
nate complex (Figure 6). The La N bond distances (2.570(2)
A
La
U
and 2.557(2) Š) of the phosphaguanidinate unit in 7 are
longer than those in the guanidinate complex [La
N
N
Chem. Eur. J. 2008, 14, 2167 – 2179
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2171

Z. Hou et al.
lanthanide phosphaguanidinate
species can be protonated by a
À
phosphine P H bond.
Reaction mechanism: On the
basis of the experimental re-
sults described above, a possi-
ble reaction mechanism for the
catalytic addition of a phos-
À
phine P H bond to a carbodi-
imide compound by 2-La could
be proposed, as shown in
Scheme 4. The acid-base meta-
thesis reaction between a phos-
À
phine P H bond and the
À
La benzyl bond should yield
Scheme 3. Formation of a lanthanum phosphaguanidinate and its reaction with diphenylphosphine.
straightforwardly
a phosphide
Figure 4. ORTEP drawing of 4 with 30% thermal ellipsoids. Hydrogen
atoms are omitted for clarity. Selected bond lengths [Š] and angles [8]:
À
À
À
À
La1 P1 3.0697(16), La1 N1 2.372(5), La1 O1 2.560(3), La1 O2
À
À
À
À
2.583(3), La1 C1 2.670(5), La1 C2 2.772(5), La1 C3 2.9276, La1 C4
À
À
À
À
2.904(5), La1 C5 2.749(5), La1 Cp(centroid) 2.541(6); N1 La1 Cp-
T
À
À
À
À
A
U
À
À
Figure 5. ORTEP drawing of 5 with 30% thermal ellipsoids. Hydrogen
atoms are omitted for clarity. Selected bond lengths [Š] and angles [8]:
119.71(10), O1 La1 O277.81(13).
À
À
À
À
La1 P1 3.1427(12), La1 P1’ 3.0675(13), La1 N1 2.372(3), La1 C13
À
À
À
À
2.677(3), La1 C14 2.752(3), La1 C15 2.866(3), La1 C16 2.852(3), La1
À
À
À
C17 2.734(3), La1 Cp
92.15(8),
162.35(8), N1 La1 P1 105.47(7), N1 La1 P(1’) 107.40(8), P1 La1 P1’
65.37(3), La1 P1 La1’ 114.63(3).
A
ACHTREUNG
A
(2.448(5)
and
À
À
À
À
P1 La1 Cp
(centroid)
110.80(8),
P1’ La1 Cp
ACHTREUNG
À
À
À
À
À
À
À
À
A
ACHTREUNG
served at room temperature in [D8]THF. However, when a
1:1 mixture of 6 and diphenylphosphine was heated to 808C,
the phosphaguanidine 3a and complex 4 were formed
almost quantitatively (Scheme 3). The catalytic formation of
3a was achieved if excess amounts of diphenylphosphine
and iPrN=C=NiPr (1:1) were added to 6 in [D8]THF and
heated at 808C. The analogous reaction between 7 and di-
phenylphosphine afforded 3a and complex 4 similarly.
These results clearly demonstrate for the first time that a
species such as A. Nucleophilic addition of the phosphide
species to a carbodiimide would afford the phosphaguanidi-
nate species B, which on abstraction of a proton from anoth-
er molecule of phosphine would yield the phosphaguanidine
product and regenerate the phosphide A. The isolation of 4
and 6 and the transformation of 6 to 3a and 4 by reaction
with diphenylphosphine strongly support this mechanism
(see Scheme 3).
2172
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Chem. Eur. J. 2008, 14, 2167 – 2179

Rare-Earth Metal Catalyst Precursors
FULL PAPER
the catalytic formation of a phosphaguanidine compound
proceeds through the nucleophilic addition of a phosphide
species, which is formed by the acid-base reaction between a
À
rare-earth-metal-alkyl bond and a phosphine P H bond, to
a carbodiimide, followed by the protonolysis of the resultant
À
phosphaguanidinate species by a phosphine P H bond.
Experimental Section
All reactions were carried out under a dry and inert atmosphere by using
either standard Schlenk techniques or under a nitrogen atmosphere in an
MBRAUN glovebox. The argon was purified by passage through a Dry-
clean column (4 Š molecular sieves, Nikka Seiko) and a Gasclean GC-
XR column (Nikka Seiko). The nitrogen in the glovebox was constantly
circulated through a copper/molecular sieves catalyst unit. The oxygen
and moisture concentrations in the glovebox atmosphere were monitored
by an O2/H2O Combi-Analyzer (MBRAUN) to ensure both were always
below 1 ppm. Solvents were distilled from sodium/benzophenone ketyl,
and dried over fresh Na. [D6]Benzene, [D8]toluene, and [D8]THF (all
99+atom% D) were obtained from Acros Organics, and were dried over
fresh Na chips for NMR reactions. Ph2PH and PhPH2 were purchased
from TCI. (4-MeC6H4)2PH and (3,5-Me2C6H3)2PH were purchased from
Strem. Other phosphines were prepared according to literature.[15] (4-
BrC6H4)2PH (new compound) was synthesized analogously.[15a] Phospha-
guanidines 3a[9c] and 3b[9c] are known compounds. All other phosphagua-
nidines reported in this paper are new compounds. The amine ligands
(C5Me4H)SiMe2NH(C6H2Me3-2,4,6)[5e] and [Sc(CH2C6H4NMe2-o)3][16]
were prepared according to their respective published procedures.
Figure 6. ORTEP drawing of 7 with 30% thermal ellipsoids. Hydrogen
atoms are omitted for clarity. Selected bond lengths [Š] and angles [8]:
À
À
À
À
La1 N1 2.570(2), La1 N2 2.557(2), La1 N3 2.382(3), La1 O1 2.667(3),
À
À
À
À
N1 C1 1.330(4), N2 C1 1.338(4), P1 C1 1.915(3), La1 C20 2.723(3),
À
À
À
À
La1 C21 2.827(3), La1 C22 2.948(3), La1 C23 2.929(3), La1 C24
À
À
À
2.791(3), La1 Cp
N
G
À
À
À
À
À
N2 La1 Cp(centroid) 119.83(9), N3 La1 Cp(centroid) 90.52(9), O1
G
ACHTREUNG
À
À
À
À
À
La1 Cp
(centroid) 99.44(9), N1 La1 N3 95.52(8), N2 La1 N3 106.37(9),
À
À
À
À
À
À
À
N1 La1 N252.67(8), C1 N1 La1 94.92(17), C1 N2 La1 95.31(17), N1
À
À
À
À
À
C1 N2117.0(3), N1 C1 P1 126.7(2), N2 C1 P1 116.3(2).
IR spectra were obtained by using a Shimadzu IRPrestige-21 spectropho-
tometer using Nujol mulls between KBr disks. The high-resolution mass
spectroscopy (HRMS) data were recorded by using a JEOL JMS-700 in-
strument operated in EF-FAB+ mode. Samples for NMR spectroscopic
measurements were prepared under a dry and oxygen-free argon atmos-
phere or in the glovebox by use of J. Young valve NMR tubes (Wilmad
528-JY). 1H NMR, 13C NMR, and 31P NMR spectra were recorded by
means of a JEOL-AL400 spectrometer (FT, 400 MHz for 1H; 100 MHz
for 13C; 160 MHz for 31P),
a JEOL JNM-AL300 spectrometer (FT,
300 MHz for 1H; 75 MHz for 13C) or a JEOL JNM-AL270 spectrometer
(FT, 270 MHz for 1H; 68 MHz for 13C) at room temperature, unless oth-
erwise noted. Phosphorus chemical shifts were measured relative to an
external 85% aqueous solution of H3PO4. Micro elemental analyses were
performed by means of a MICRO CORDER JM10 apparatus (J-Science
Lab.).
Scheme 4. A possible mechanism of the catalytic addition of a phosphine
(4-BrC6H4)2PH: This compound was prepared according to literature[15a]
À
P H bond to a carbodiimide compound.
via reduction of (4-BrC6H4)2POH by use of 3 equiv DIBAL-H/THF to
yield a colorless solid in 86% yield; 1H NMR (300 MHz, C6D6): d=4.80
1
(d, JPH =216.9 Hz, 1H; PH), 6.82–6.87 (m, 4H; C6H4), 7.11–7.14 ppm (m,
4H; C6H4); 13C NMR (75 MHz, C6D6): d=123.6, 132.0 (d, 3JPC =6.2Hz),
133.6 (d, 1JPC =11.7 Hz), 135.6 ppm (d, 2JPC =17.9 Hz); 31P{1H} NMR
(160 MHz, C6D6): d=À43.5 ppm; HRMS: m/z: calcd for C12H1079Br2P:
342.8887 [M+H]+; found: 342.8895.
Conclusion
Half-sandwich o-dimethylaminobenzyl complexes 2-Ln
(Ln=Sc, Y, La, Pr, Sm, Nd, Gd, Lu) bearing silylene-linked
cyclopentadienyl-amido ligands have been synthesized and
structurally characterized for the first time over the full size
range of the rare-earth metal series. Such complexes serve
as efficient catalyst precursors for the catalytic addition of
[La(CH2C6H4NMe2-o)3]: This compound was prepared by a modified lit-
erature procedure.[7] LaBr3 instead of LaCl3 was used here. THF (20 mL)
was added to LaBr3 (900 mg, 2.377 mmol) at room temperature in a
Schlenk tube and sealed with a Teflon stopcock. This tube was taken out-
side and was heated at 708C for 5 h to form the thf-coordinated lantha-
num complex LaBr3(thf)4. After cooling down to room temperature, a
A
À
various phosphine P H bonds to carbodiimides, and have
THF solution (10 mL) of KCH2C6H4NMe2-o (1.236 g, 7.131 mmol) was
added to a THF suspension of lanthanum bromide at room temperature
in the glove box. After stirring for 30 min, the solvent was removed
under reduced pressure to give an oily residue, which was then dissolved
in toluene (20 mL) and filtered to remove the potassium salt. The filtrate
was concentrated and cooled down to À308C to give yellow cubic crystals
(1.125 g, 2.068 mmol, 87% yield). 1H NMR (300 MHz, C6D6, 508C): d=
1.63 (s, 6H; CH2), 1.93 (s, 18H; NMe2), 6.28 (t, 3H; aryl), 6.61–6.69 ppm
lead to the formation of a series of phosphaguanidine deriv-
atives with excellent tolerability to aromatic carbon-halogen
bonds. An increase in the rare-earth metal size, leads to a
significant increase in the catalytic activity. The isolation
and reactivity investigation of the phosphide (e.g., 4 and 5)
and phosphaguanidinate intermediates (e.g., 6) suggests that
Chem. Eur. J. 2008, 14, 2167 – 2179
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2173

Z. Hou et al.
(m, 9H; aryl); 1H NMR (300 MHz, [D8]THF, 258C): d=1.58 (s, 6H;
CH2), 2.34 (s, 18H; NMe2), 6.42(t, J=7.5 Hz, 3H; aryl), 6.67 (d, J=
8.1 Hz, 3H; aryl), 6.82(t, J=7.5 Hz, 3H; aryl), 7.04 ppm (d, J=8.1 Hz,
3H; aryl).
SiMe2), 1.10 (brs, 4H; b-CH2,thf), 1.92(s, 6H; C 5Me4), 2.02 (brs, 6H;
NMe2), 2.20 (s, 2H; CH2), 2.31 (s, 3H; p-Me), 2.42, (s, 6H; C5Me4 or o-
Me), 2.49 (s, 6H; C5Me4 or o-Me), 2.83 (brs, 4H; a-CH2, thf), 6.25 (t, J=
7.8 Hz, 1H; aryl), 6.49 (d, J=7.2Hz, 1H; aryl), 6.75 (t, J=8.1 Hz, 1H;
aryl), 6.86 (d, J=6.3 Hz, 1H; aryl), 6.97 ppm (s, 2H; aryl); 1H NMR
(300 MHz, [D8]THF): d=0.33 (s, 6H; SiMe2), 1.73 (s, 2H; CH2), 1.97
(brs, 6H; NMe2), 1.99 (s, 6H; C5Me4), 2.17 (s, 3H; p-Me), 2.27, (s, 6H;
C5Me4 or o-Me), 2.30 (s, 6H; C5Me4 or o-Me), 6.36 (t, J=8.7 Hz, 1H;
aryl), 6.65 (d, J=6.3 Hz, 1H; aryl), 6.73 (t, J=6.6 Hz, 1H; aryl), 6.76 (s,
2H; aryl), 6.83 ppm (d, J=8.3 Hz, 1H; aryl); 13C NMR (75 MHz,
[D8]THF): d=6.7, 11.4, 14.5, 20.8, 21.3, 26.4, 41.4 (NMe2), 44.5 (CH2),
68.2, 107.2, 116.7, 119.1, 121.8, 123.2, 126.89, 126.94 127.2, 127.6, 129.2,
131.6, 136.5, 144.5, 152.0 ppm; elemental analysis calcd (%) for
C33H49N2OSiLa: C 60.35, H 7.52, N 4.27; found: C 60.68, H 7.41, N 4.20.
[Pr(CH2C6H4NMe2-o)3]: Starting from PrBr3 (3.806 g, 10 mmol),
[Pr(CH2C6H4NMe2-o)3] was obtained as yellow green cubic crystals
(yield, 5.018 g, 9.2mmol, 92% yield) in a manner analogous to that de-
scribed for the synthesis of [La(CH2C6H4NMe2-o)3]. 1H NMR (300 MHz,
[D8]THF, 508C): d=À23.37 (brs, 18H; NMe2), À9.50 (brs, 3H; aryl),
À0.85 (brs, 3H aryl), 8.59 (brs, 3H; aryl), 23.38 ppm (brs, 3H; aryl);
13C NMR (75 MHz, [D8]THF, 508C): d=À29.4, 78.5, 100.2, 113.1, 135.8,
162.4 ppm; elemental analysis calcd (%) for C27H36PrN3: C 59.67, H 6.68,
N 7.73; found: C 59.84, H 6.52, N 7.43. The 1H NMR signals for benzyl
protons was not observed.
A
N
G
G
[Nd(CH2C6H4NMe2-o)3]: Starting from anhydrous NdBr3 (1.919 g,
5 mmol), [Nd(CH2C6H4NMe2-o)3] was obtained as dark green cubic crys-
tals (2.261 g, 4.15 mmol, 83% yield) in a manner analogous to that de-
scribed for the synthesis of [La(CH2C6H4NMe2-o)3]. 1H NMR (300 MHz,
[D8]THF, 508C): d=À11.94 (brs, 18H; NMe2), À1.02(brs, 3H; aryl),
1.12(brs, 3H aryl), 9.46 (brs, 3H; aryl), 14.69 (brs, 3H; aryl), 17.12ppm
(brs, 6H; CH2); 13C NMR (68 MHz, [D8]THF, 508C): d=85.7, 98.6,
113.5, 139.3, 143.6, 161.2ppm; elemental analysis calcd (%) for
C27H36NdN3: C 59.30, H 6.64, N 7.68; found: C 59.02, H 6.28, N 7.65.
(0.314 g, 1 mmol) at room temperature. After stirring for 2h at 50 8C, the
solvent was removed under reduced pressure. The residue was washed by
hexane and dissolved in THF. Slow evaporation of the solvent gave 2-Pr
as light green crystals (0.396 g, 0.60 mmol, 60% yield). 1H NMR
(300 MHz, C6D6, 508C): d=À8.29 (brs, 4H; thf), 2.39 (brs, 6H; SiMe2),
3.19 (s, 3H; p-Me), 6.60 (brs, 2H; aryl), 7.07 (s, 1H; aryl), 14.52 (s, 1H;
aryl), 14.59 (s, 1H; aryl), 22.53 ppm (brs, 1H; aryl); 1H NMR (300 MHz,
[D8]THF, 508C): d=2.25 (brs, 6H; SiMe2), 3.01 (s, 3H; p-Me), 6.28 (s,
2H; aryl), 7.36 (s, 1H; aryl), 13.54 (s, 1H; aryl), 16.09 (s, 1H; aryl),
18.63 ppm (s, 1H; aryl), other signals were not observed because of the
[Y(CH2C6H4NMe2-o)3]: This compound was prepared by a modified liter-
ature procedure.[7] LiCH2C6H4NMe2-o instead of KCH2C6H4NMe2-o was
used here. Anhydrous yttrium chloride (976 mg, 5 mmol) was suspended
in THF(20 mL). A THF solution (20 mL) of LiCH2C6H4NMe2-o (2.117 g,
A
influence of the paramagnetic Pr
(III) ion; 13C NMR (75 MHz, [D8]THF,
508C): d=18.0, 26.6, 68.2, 108.4, 117.6, 123.5, 125.1, 134.9, 151.0, 155.7,
166.9 ppm; elemental analysis calcd (%) for C33H49N2OSiPr: C 60.17, H
7.50, N 4.25; found: C 60.26, H 7.60, N 4.34.
15 mmol) was slowly added at room temperature. After stirring for
30 min, the solvent was removed under reduced pressure. The residue
was dissolved in toluene (30 mL) and filtered to remove lithium salt. The
filtrate was concentrated and cooled down to À308C to give
[Y(CH2C6H4NMe2-o)3] as yellow cubic crystals (1.843 g, 75% yield).
1H NMR (400 MHz, C6D6): d=1.63 (s, 6H; CH2), 2.11 (s, 18H; NMe2),
6.66 (t, J=6.6 Hz, 3H; aryl), 6.83 (d, J=8.1 Hz, 3H; aryl), 7.00 (t, J=
8.1 Hz, 3H; aryl), 7.11 ppm (d, J=6.6 Hz, 3H; aryl).
A
G
N
(0.314 g, 1 mmol) at room temperature. After stirring for 2h at 50 8C, the
solvent was removed under reduced pressure. The residue was washed
with hexane and dissolved in toluene. Slow evaporation of the solvent
gave 2-Nd as green crystals (0.410 g, 0.61 mmol, 61% yield). 1H NMR
(300 MHz, C6D6, 508C): d=À6.30 (brs, 4H; thf), À2.98 (brs, 4H; thf),
3.66 (s, 3H; p-Me), 4.72(s, 6H; SiMe 2), 7.49 (s, 2H; aryl), 10.86 (s, 1H;
aryl), 13.35 (s, 1H; aryl), 16.71 ppm (s, 1H; aryl); 1H NMR (300 MHz,
[D8]THF, 508C): d=3.42(s, 3H; p-Me), 4.35 (s, 6H; SiMe2), 4.86 (s, 1H;
aryl), 7.15 (s, 2H; aryl), 11.44 (s, 1H; aryl), 12.89 (s, 1H; aryl), 15.09 (s,
1H; aryl), other signals were not observed because of the influence of
[Sm(CH2C6H4NMe2-o)3]: Starting from anhydrous SmCl3 (1.283 g,
5 mmol), [Sm(CH2C6H4NMe2-o)3] was obtained as red purple cubic crys-
tals (2.530 g, 4.6 mmol, 92% yield) in a manner analogous to that de-
scribed for the synthesis of [Y(CH2C6H4NMe2-o)3]. 1H NMR (300 MHz,
[D8]THF): d=À1.53 (s, 18H; NMe2), 4.79 (s, 3H; aryl), 7.05 (s, 3H;
aryl), 7.19 (s, 3H aryl), 9.60 (s, 3H; aryl), 13.94 ppm (s, 6H; CH2);
13C NMR (68 MHz, [D8]THF): d=40.0, 112.2, 123.6, 124.5, 128.2, 128.9,
131.5, 155.2ppm; elemental analysis calcd (%) for C 27H36SmN3: C 58.65,
H 6.56, N 7.60; found: C 59.14, H 6.56, N 7.41.
the paramagnetic Nd
(III) ion; 13C NMR (75 MHz, [D8]THF, 508C): d=
16.7, 26.6, 68.2, 98.4, 103.4, 117.7, 122.3, 129.1, 138.0, 154.3, 168.0 ppm; el-
emental analysis calcd (%) for C33H49N2OSiNd: C 59.86, H 7.46, N 4.23;
found: C 59.82, H 7.36, N 4.11.
[Gd(CH2C6H4NMe2-o)3]: Starting from anhydrous GdCl3 (2.636 g,
10 mmol), [Gd(CH2C6H4NMe2-o)3] was obtained as yellow crystals
(4.759 g, 8.5 mmol, 85% yield) in a manner analogous to that described
for the synthesis of [Y(CH2C6H4NMe2-o)3]. The 1H NMR spectrum of
[Gd(CH2C6H4NMe2-o)3] was not informative because of the influence of
U
G
the paramagnetic Gd(III) ion. Elemental analysis calcd (%) for
N
C27H36GdN3: C 57.92, H 6.48, N 7.51; found: C 57.93, H 6.30, N 7.40.
a
(0.314 g, 1 mmol) at room temperature. After stirring for 2h at 50 8C, the
solvent was removed under reduced pressure. The residue was washed by
hexane and recrystallization from THF gave 2-Sm as red crystals
(0.419 g, 0.62mmol, 62% yield). 1H NMR (400 MHz, C6D6): d=À0.20
(brs, 4H; thf), 0.59 (brs, 4H; thf), 1.18 (s, 6H; SiMe2), 2.20 (s, 3H; p-
Me), 6.28 (d, J=7.5 Hz, 1H; aryl), 6.90 (s, 2H; aryl), 7.46 (t, J=7.1 Hz,
1H; aryl), 7.51 (brs, 2H; CH2), 7.70 (t, J=7.1 Hz, 1H; aryl), 10.15 ppm
(d, J=7.9 Hz, 1H; aryl), other signals were not observed because of the
[Lu(CH2C6H4NMe2-o)3]: Starting from anhydrous LuCl3 (2.251 g,
8 mmol), [Lu(CH2C6H4NMe2-o)3] was obtained as yellow cubic crystals
(3.558 g, 6.16 mmol, 77% yield) in a manner analogous to that described
for the synthesis of [Y(CH2C6H4NMe2-o)3]. 1H NMR (300 MHz, C6D6):
d=1.48 (s, 6H; CH2), 2.17 (s, 18H; NMe2), 6.70–6.78 (m, 6H; aryl), 7.01
(t, J=7.5 Hz, 3H; aryl), 7.09 ppm (d, J=7.7 Hz, 3H; aryl); 13C NMR
(75 MHz, C6D6): d=44.8 (NMe2), 48.4 (CH2), 118.8, 119.1, 127.5, 129.6,
139.1, 142.8 ppm (aromatics); elemental analysis calcd (%) for
C27H36LuN3: C 56.15, H 6.28, N 7.28; found: C 56.18, H 6.18, N 7.14.
influence of the paramagnetic Sm
(III) ion; 13C NMR (75 MHz, [D8]THF,
A
508C): d=8.3, 14.8, 21.3, 22.5, 26.5, 43.9, 68.2, 102.9, 114.4, 125.7, 125.8,
127.2, 129.9, 132.0, 139.6, 160.0, 163.7 ppm; elemental analysis calcd (%)
for C33H49N2OSiSm: C 59.32, H 7.39, N 4.19; found: C 59.19, H 7.01, N
3.99.
A
N
G
G
(0.627 g, 2mmol) at room temperature. After stirring for 2h at room
temperature, the solvent was removed under reduced pressure. The resi-
due was washed by ether and dissolved in toluene (50 mL). Slow evapo-
ration of the solvent gave 2-La as light yellow crystals (1.138 g,
A
G
G
N
a
1.74 mmol, 87% yield). H NMR (300 MHz, C6D6, 508C): d=0.70 (s, 6H;
2174
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Chem. Eur. J. 2008, 14, 2167 – 2179

Rare-Earth Metal Catalyst Precursors
FULL PAPER
solvent was removed under reduced pressure. The residue was washed by
ether and dissolved in toluene (30 mL). Slow evaporation of the solvent
gave 2-Gd as yellow crystals (0.405 g, 0.6 mmol, 60%). The 1H NMR
spectrum of 2-Gd was not informative because of the influence of the
149.0 ppm; elemental analysis calcd (%) for C33H49N2OSiSc: C 70.98, H
8.42, N 5.71; found: C 70.89, H 8.39, N 5.37.
Typical procedures for catalytic addition reactions of phosphines to car-
bodiimides
paramagnetic Gd
C33H49N2OSiGd: C 58.71, H 7.32, N 4.15; found: C 58.33, H 7.07, N 4.31.
[{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Lu(CH2C6H4NMe2-o)(thf)] (2-Lu): To
a THF solution (8 mL) of [Lu(CH2C6H4NMe2-o)3] (0.578 g, 1 mmol) was
added THF solution (2mL) of (C 5Me4H)SiMe2NH(C6H2Me3-2,4,6)
A
NMR tube reaction: In the glovebox, a J. Young valve NMR tube was
charged with 2-La (7 mg, 0.01 mmol), [D8]THF (0.45 mL), diphenylphos-
phine (63 mg, 0.35 mmol), N,N’-diisopropylcarbodiimide (43 mg,
0.34 mmol). Release of o-dimethylaminotoluene was confirmed by
1H NMR. Formation of 3a and disappearance of diphenylphosphine were
easily monitored by 31P NMR. The conversion of diphenylphosphine was
determined by 31P NMR. No other coupling products were observed.
A
G
A
ACHTREUNG
a
(0.314 g, 1 mmol) at room temperature. After stirring for overnight at
708C, the solvent was removed under reduced pressure. The residue was
washed by hexane and dissolved in toluene (30 mL). Slow evaporation of
the solvent gave 2-Lu as colorless crystals (0.476 g, 0.69 mmol, 69%
Preparative scale reaction: In the glovebox, a THF solution (3 mL) of di-
phenylphosphine (376 mg, 2.02 mmol) was added to a THF solution
(2mL) of 2-La (13 mg, 0.02mmol) in a Schlenk tube. Then N,N’-diiso-
propylcarbodiimide (252 mg, 2.00 mmol) was added to the above reaction
mixture. After 1 h of stirring at 808C, the solvent was removed under re-
duced pressure. The residue was extracted with hexane and filtered to
give a clean solution. After removing the solvent under vacuum, the resi-
due was recrystallized in hexane to provide a colorless solid 3a.
1
yield). H NMR (300 MHz, C6D6): d=0.69 (s, 6H; SiMe2), 1.30 (brs, 4H;
b-CH2, thf), 1.68 (brs, 8H; NMe2 and CH2), 1.94 (s, 6H; C5Me4), 2.29 (s,
3H; p-Me), 2.36 (s, 6H; C5Me4 or o-Me), 2.42 (s, 6H; C5Me4 or o-Me),
3.37 (brs, 4H; a-CH2, thf), 6.39 (d, J=8.1 Hz, 1H; aryl), 6.58 (t, J=
6.9 Hz, 1H; aryl), 6.87 (t, J=6.9 Hz, 1H; aryl), 7.07 ppm (d, J=7.8 Hz,
1H; aryl); 1H NMR (300 MHz, [D8]THF): d=0.33 (s, 6H; SiMe2), 1.50
(brs, 2H; CH2), 2.02 (brs, 6H; NMe2), 2.14 (s, 6H; C5Me4 or o-Me), 2.22
(s, 3H; p-Me), 2.32 (s, 12H; C5Me4 or o-Me), 6.57 (t, J=7.5 Hz, 1H;
aryl), 6.65–6.85 ppm (m, 5H; aryl); 13C NMR (75 MHz, [D8]THF): d=
5.6, 12.0, 14.8, 20.8, 21.2, 26.4, 44.9 (brs, NMe2), 49.5 (CH2), 68.2, 105.3,
118.0, 119.5, 122.5, 126.6, 127.7, 128.4, 129.2, 132.6, 145.8, 146.2,
152.8 ppm; elemental analysis calcd (%) for C33H49N2OSiLu: C 57.21, H
7.13, N 4.04; found: C 56.58, H 6.78, N 3.89.
It should be pointed out that the phosphaguanidine compounds reported
in this paper are very sensitive to oxygen, and must be stored under an
inert atmosphere.
iPrN=C
A
ACHTREUNG
(300 MHz, C6D6): d=0.94 (d, J=6.6 Hz, 6H; CH
AHCTREUNG
3
6.3 Hz, 6H; CH
ACHTREUNG
CH), 7.03–7.05 (m, 6H; C6H5), 7.42–7.47 ppm (m, 4H; C6H5); 13C NMR
(75 MHz, C6D6): d=22.5, 25.3, 42.9, 52.2 (d, 3JPC =35.3 Hz), 129.0 (d,
3JPC =6.8 Hz), 129.3, 134.3 (d, 2JPC =19.8 Hz), 135.5 (d, 1JPC =13.7 Hz),
152.4 ppm (d, 1JPC =31.6 Hz); 31P{1H} NMR (160 MHz, C6D6): d=
A
G
G
N
a
(0.314 g, 1 mmol) at room temperature. After stirring for overnight at
508C, the solvent was removed under reduced pressure. The residue was
washed by ether and dissolved in toluene (30 mL). Slow evaporation of
the solvent gave 2-Y as light yellow crystals (0.534 g, 0.87 mmol, 87%
yield). 1H NMR (300 MHz, C6D6, 508C): d=0.66 (s, 6H; SiMe2), 1.15
À
À18.5 ppm; IR (Nujol): n˜ =3431 (N H), 1599 (C=N), 1462, 1377, 1173,
1026, 743, 696 cmÀ1
HRMS: m/z: calcd for C19H26N2P: 313.1834
[M+H]+;
found: 313.1853.
CyN=C(PPh2)
;
G
ACHTREUNG
E
(NHCy) (3b): colorless solid, yield 99%; 1H NMR
(300 MHz, C6D6): d=0.92–1.93 (m, 20H; Cy), 3.81 (d, 3J=6.9 Hz, 1H;
NH), 4.05–4.19 (m, 2H; CH), 7.02–7.13 (m, 6H; C 6H5), 7.48–7.53 ppm
(m, 4H; C6H5); 13C NMR (75 MHz, C6D6): d=24.6, 25.2, 26.2, 26.3, 32.5,
(brs, 4H; b-CH2, thf), 1.92(brs, 8H; NMe and CH2), 2.00 (s, 6H;
2
C5Me4), 2.29 (s, 3H; p-Me), 2.39 (s, 6H; C5Me4 or o-Me), 2.40 (s, 6H;
C5Me4 or o-Me), 3.00 (brs, 4H; a-CH2, thf), 6.40–6.47 (m, 2H; aryl),
6.78–6.82(m, 1H; aryl), 6.95 (s, 2H; aryl), 7.01 ppm (d, J=7.8 Hz, 1H;
aryl); 1H NMR (300 MHz, [D8]THF): d=0.30 (s, 6H; SiMe2), 1.60 (brs,
2H; CH2), 2.00 (brs, 6H; NMe2), 2.10 (s, 6H; C5Me4 or o-Me), 2.17 (s,
3H; p-Me), 2.28 (s, 6H; C5Me4 or o-Me), 2.29 (s, 6H; C5Me4 or o-Me),
6.48 (t, J=6.9 Hz, 1H; aryl), 6.75 (s, 2H; aryl), 6.75–6.81 ppm (m, 3H;
aryl); 13C NMR (75 MHz, [D8]THF): d=5.9, 12.0, 14.8, 20.8, 21.5, 26.4,
43.9 (brs, NMe2), 47.0 (d, JY-C =31.1 Hz, CH2), 68.2, 106.1, 118.7, 119.1,
122.6, 123.6, 126.0, 127.0, 127.3, 128.0, 128.9, 129.2, 129.5, 132.0, 142.7,
145.3, 152.8 ppm; elemental analysis calcd (%) for C33H49N2OSiY: C
65.32, H 8.14, N 4.62; found: C 64.64, H 7.81, N 4.35.
3
3
35.7, 49.1, 60.3 (d, JPC =33.4 Hz), 129.0 (d, JPC =6.8 Hz), 129.3, 134.2 (d,
2JPC =19.2Hz), 135.7 (d, 1JPC =14.9 Hz), 152.4 ppm (d, 1JPC =31.6 Hz);
31
1
À
P{ H} NMR (160 MHz, C6D6): d=À18.1 ppm; IR (Nujol): n˜ =3431 (N
H), 1599 (C=N), 1461, 1377, 1153, 1027, 742, 695 cmÀ1; HRMS: m/z:
calcd for C25H34N2P: 393.2460 [M+H]+; found: 393.2455.
tBuN=C
N
N
(300 MHz, C6D6): d=1.27 (t, J=7.2Hz, 3H; CH 2CH3), 1.33 (s, 9H; C-
A
7.42–7.47 ppm (m, 4H; C6H5); 13C NMR (75 MHz, C6D6): d=17.7, 28.7,
46.9 (d, 3JPC =36.5 Hz), 52.1, 129.1 (d, 3JPC =6.8 Hz), 129.3, 134.3 (d,
2JPC =19.2Hz), 135.4 (d, 1JPC =14.3 Hz), 153.8 ppm (d, 1JPC =33.4 Hz);
A
G
A
31
ACHTREUNG
H), 1609 (C=N), 1462, 1377, 1219, 1028, 743, 696 cmÀ1; HRMS: m/z:
calcd for C19H26N2P: 313.1834 [M+H]+; found: 313.1840.
the reaction of (C5Me4H)SiMe2NH(C6H2Me3-2,4,6) (0.879 g, 2.8 mmol)
with n-butyl lithium (5.6 mmol, 2.67 (M), 2.1 mL), was added to a THF
solution (15 mL) of ScCl3 (0.424 g, 2.8 mmol) at room temperature. After
stirring for overnight, a THF solution (10 mL) of LiCH2C6H4NMe2-o
(0.395 g, 2.8 mmol) was slowly added to the solution. After stirring for
2h, the solvent was removed under reduced pressure. The residue was
dissolved in toluene (50 mL) and filtrated to remove Li salt. The solvent
was removed under reduced pressure to give orange oil. The product was
dissolved in small amount of toluene. Ether was slowly layered to the so-
lution to afford 2-Sc as yellow crystals (0.992g, 1.876 mmol, 67% yield).
1H NMR (300 MHz, C6D6): d=0.64 (s, 3H; SiMe2), 0.71 (s, 3H; SiMe2),
1.15 (s, 3H; Me), 1.28 (d, 1H; J=10.5 Hz, CH2), 1.78 (s, 3H; Me), 1.87
(s, 3H; Me), 1.97 (d, 1H; J=10.5 Hz, CH2), 2.13 (s, 3H; Me), 2.16 (s,
3H; Me), 2.24, (s, 3H; Me), 2.30 (s, 3H; Me), 2.40 (s, 3H; Me), 2.41 (s,
3H; Me), 6.45 (d, J=8.1 Hz, 1H; aryl), 6.68 (t, J=7.5 Hz, 1H; aryl), 6.91
(s, 2H; m-H), 6.92(t, J=7.5 Hz, 1H; aryl), 7.02ppm (d, J=8.1 Hz, 1H;
aryl); 13C NMR (75 MHz, C6D6): d=4.5, 6.7, 10.2, 11.4, 14.2, 14.7, 20.4,
20.8, 20.9, 42.2, 44.1, 45.8, 46.9, 107.4, 118.4, 121.6, 124.2, 126.2, 127.6,
127.9, 128.2, 129.0, 129.5, 129.8, 131.3, 131.4, 132.2, 138.3, 141.3,
iPrN=C{P
C
N
U
3
(d, J=6.0 Hz, 6H; CH
R
NH), 4.32–4.43 (m, 2H; CH), 6.94–7.09 ppm (m, 8H; C6H4); 13C NMR
(75 MHz, C6D6): d=21.1 (d, 3JPC =21.7 Hz), 22.4, 25.5, 42.7, 52.8 (d,
3JPC =37.1 Hz), 126.8, 129.6, 130.6 (d, 3JPC =4.3 Hz), 133.3, 142.9 (d, JPC
or 2JPC =26.0 Hz, 2C), 151.9 ppm (d, 1JPC =30.3 Hz); 31P{1H} NMR
À
(160 MHz, C6D6): d=À33.5 ppm; IR (Nujol): n˜ =3443 (N H), 1594 (C=
N), 1455, 1377, 1168, 1088, 966, 763 cmÀ1
HRMS: m/z: calcd for
C21H30N2P: 341.2147 [M+H]+; found: 341.2153.
iPrN=C{P(C6H4Me-3)2}(NHiPr) (3e): colorless solid, yield 99%;
1H NMR (400 MHz, C6D6): d=0.85 (d, J=6.4 Hz, 6H; CH
(CH3)2), 1.12
(d, J=6.0 Hz, 6H; CH(CH3)2), 1.90 (s, 6H; Me), 3.63 (d, J=6.4 Hz, 1H;
;
A
ACHTREUNG
AHCTREUNG
AHCTREUNG
NH), 4.16–4.33 (m, 2H; CH), 6.80 (d, J=7.6 Hz, 2H; C6H4), 6.93 (dd, J=
7.6 Hz, J=7.6 Hz, 2H; C6H4), 7.18–7.26 ppm (m, 4H; C6H4); 13C NMR
(100 MHz, C6D6): d=21.5, 22.8, 25.6, 43.0, 52.3 (d, 3JPC =35.5 Hz), 129.0
3
2
2
(d, JPC =6.6 Hz), 130.2, 131.3 (d, JPC =17.3 Hz), 135.0 (d, JPC =23.1 Hz),
Chem. Eur. J. 2008, 14, 2167 – 2179
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2175

Z. Hou et al.
1
135.5 (d, 1JPC =14.0 Hz), 138.5 (d, 3JPC =7.4 Hz), 152.6 ppm (d, JPC
=
3H; CH
G
N
32.1 Hz); 31P{1H} NMR (160 MHz, C6D6): d=À18.3 ppm; IR (Nujol): n˜ =
CH2CH3), 3.54 (d, J=6.4 Hz, 1H; NH), 4.25–4.30 (m, 1H; CH), 4.51–
4.56 (m, 1H; CH), 7.05–7.15 (m, 3H; C6H5), 7.39–7.43 ppm (m, 2H;
C6H5); 13C NMR (100 MHz, C6D6): d=10.7 (d, 2JPC =16.5 Hz), 18.6 (d,
1JPC =14.0 Hz), 22.5, 22.8, 25.8, 26.0, 42.6, 52.0 (d, 3JPC =36.3 Hz), 128.8
3429 (N H), 1599 (C=N), 1462, 1377, 1175, 1119, 777, 696 cmÀ1; HRMS:
À
m/z: calcd for C21H30N2P: 341.2147 [M+H]+, found: 341.2150.
iPrN=C{P
1H NMR (300 MHz, C6D6): d=0.89 (d, J=6.3 Hz, 6H; CH
(d, J=6.0 Hz, 6H; CH(CH3)2), 1.94 (s, 6H; Me), 3.67 (d, J=6.0 Hz, 1H;
A
ACHTREUNG
3
2
1
(d, JPC =8.2 Hz), 128.9, 132.7 (d, JPC =18.1 Hz), 137.0 (d, JPC =17.3 Hz),
AHCTREUNG
154.4 ppm (d, 1JPC =34.6 Hz); 31P{1H} NMR (160 MHz, C6D6): d=
ACHTREUNG
À
À29.0 ppm; IR (Nujol): n˜ = 3432(N H), 1598 (C=N), 1464, 1377, 1174,
NH), 4.23–4.35 (m, 2H; CH), 6.85 (d, J=7.5 Hz, 4H; C6H4), 7.33 ppm
1118, 1028, 742, 697 cmÀ1; HRMS: m/z: calcd for C15H26N2P: 265.1834
[M+H]+; found: 265.1840.
(dd, J=7.5 Hz, J=7.8 Hz, 4H; C6H4); 13C NMR (75 MHz, C6D6): d=
3
3
21.2, 22.6, 25.4, 42.8, 52.0 (d, JPC =34.6 Hz), 129.9 (d, JPC =6.8 Hz), 132.3
1
(d, 1JPC =12.4 Hz), 134.4 (d, 2JPC =19.2Hz), 139.3, 153.0 ppm (d, JPC
=
iPrN=C
(400 MHz, C6D6): d=0.97 (d, J=6.4 Hz, 3H; CH
6.4 Hz, 3H; CH(CH3)2), 1.24 (d, J=6.4 Hz, 3H; CH
6.4 Hz, 3H; CH(CH3)2), 4.28–4.39 (m, 4H; PH, NH and CH), 6.99–7.06
(PHPh)
ACHTREUNG
31.5 Hz); 31P{1H} NMR (160 MHz, C6D6): d=À20.0 ppm; IR (Nujol): n˜ =
AHCTREUNG
3429 (N H), 1599 (C=N), 1460, 1377, 1175, 1020, 806, 721 cmÀ1; HRMS:
À
G
ACHTREUNG
m/z: calcd for C21H30N2P: 341.2147 [M+H]+; found: 341.2173.
U
(m, 3H; C6H5), 7.51–7.55 ppm (m, 2H; C6H5); 13C NMR (100 MHz,
iPrN=C{P(C6H3Me2-3,5)2
1H NMR (400 MHz, C6D6): d=1.02(d, J=6.8 Hz, 6H; CH
(d, J=6.0 Hz, 6H; CH(CH3)2), 2.04 (s, 12H; Me), 3.89 (d, J=6.8 Hz,
ACHTREUNG
C6D6): d=22.6, 25.6 (d, 4JPC =8.2Hz), 43.1, 52.9 (d, 3JPC =37.1 Hz), 129.3
AHCTREUNG
3
1
2
(d, JPC =6.6 Hz), 129.6, 133.4 (d, JPC =18.1 Hz), 134.1 (d, JPC =19.0 Hz),
ACHTREUNG
151.5 ppm (d, 1JPC =36.2Hz); 31P{1H} NMR (160 MHz, C6D6): d=
1H; NH), 4.34–4.50 (m, 2H; CH), 6.75 (s, 2H; C 6H3), 7.26 ppm (d, J=
8.0 Hz, 4H; C6H3); 13C NMR (100 MHz, C6D6): d=21.4, 22.8, 25.6, 43.0,
À
À35.0 ppm; IR (Nujol): n˜ =3414 (N H), 1601 (C=N), 1462, 1377,
721 cmÀ1; HRMS: m/z: calcd for C13H22N2P: 237.1521 [M+H]+; found:
1
52.2 (d, 3JPC =34.6 Hz), 131.2, 132.1 (d, 2JPC =19.8 Hz), 135.4 (d, JPC
=
14.0 Hz), 138.4 (d, 3JPC =7.4 Hz), 153.0 ppm (d, 1JPC =33.0 Hz);
237.1526.
31
1
À
P{ H} NMR (160 MHz, C6D6): d=À18.0 ppm; IR (Nujol): n˜ =3428 (N
A
G
N
A
H), 1599 (C=N), 1462, 1377, 1175, 1123, 847, 692 cmÀ1; HRMS: m/z:
calcd for C23H34N2P: 369.2460 [M+H]+; found: 369.2453.
solution of 2-La (153 mg, 0.233 mmol) in THF (2 mL) was treated with a
solution of diphenylphosphine (43 mg, 0.233 mmol) in THF (3 mL).
After stirring at room temperature for 5 h, the solvent was removed
under reduced pressure, and the residue was extracted with THF fol-
lowed by filtering to give a clean solution. The solution volume was re-
duced under vacuum to precipitate 4 as light yellow crystalline powder
(167 mg, 0.214 mmol, 92% yield). Single crystals of 4 suitable for X-ray
analysis were grown in THF/ether at room temperature overnight.
1H NMR (400 MHz, [D8]THF): d=0.20 (s, 6H; SiMe2), 1.72(brs, 8H; b-
iPrN=C{P(C6H4OMe-4)2
1H NMR (300 MHz, C6D6): d=1.01 (d, J=6.6 Hz, 6H; CH
(d, J=6.3 Hz, 6H; CH(CH3)2), 3.26 (s, 6H; CH3O), 3.79 (d, J=6.6 Hz,
ACHTREUNG
AHCTREUNG
ACHTREUNG
1H; NH), 4.30–4.49 (m, 2H; CH), 6.73 (d, J=8.7 Hz, 4H; C6H4),
7.43 ppm (dd, J=8.1 Hz, J=7.5 Hz, 4H; C6H4); 13C NMR (75 MHz,
3
C6D6): d=22.6, 25.4, 42.8, 51.8 (d, 3JPC =34.1 Hz), 54.7, 114.8 (d, JPC
=
1
1
8.0 Hz), 126.4 (d, JPC =11.2Hz), 135.9 (d, 2JPC =21.1 Hz), 153.6 (d, JPC
=
33.0 Hz), 161.1 ppm; 31P{1H} NMR (160 MHz, C6D6): d=À21.2 ppm; IR
CH2, THF), 1.99 (s, 6H; o- C6H2
(s, 6H; C5Me4), 2.23 (s, 6H; C5Me4), 3.57 (brs, 8H; a-CH2, THF), 6.58 (s,
G
G
À
(Nujol): n˜ =3427 (N H), 1597 (C=N), 1498, 1459, 1377, 1285, 1249, 1177,
1092, 1035, 827, 798 cmÀ1; HRMS: m/z: calcd for C21H30N2O2P: 373.2045
2H; C6H2(CH3)3), 7.20–7.25 (m, 6H; C6H5), 7.31–7.35 ppm (m, 4H;
U
[M+H]+; found: 373.2050.
C6H5); 13C NMR (100 MHz, [D8]THF): d=6.2, 10.9, 13.8, 19.9, 20.4, 25.5,
3
}(NHiPr) (3i): colorless solid, yield 97%; 1H NMR
(CH3)2), 1.23 (d, J=
67.3, 107.0, 120.7, 123.8, 125.2, 127.7, 127.9, 128.0 (d, JPC =5.8 Hz), 130.6,
iPrN=C{P
(400 MHz, C6D6): d=0.91 (d, J=6.8 Hz, 6H; CH
6.0 Hz, 6H; CH(CH3)2), 3.43 (d, J=5.6 Hz, 1H; NH), 4.24–4.29 (m, 2H;
CH), 7.00 (d, J=8.0 Hz, 4H; C6H4), 7.09 ppm (dd, J=8.0 Hz, J=7.6 Hz,
A
132.4 (d, 2JPC =18.1 Hz), 139.6 (d, 1JPC =14.8 Hz), 153.2ppm;
31P{1H} NMR (160 MHz, [D8]THF): d=À14.5 ppm; IR (Nujol): n˜ =2956,
2923, 2854, 1572, 1466, 1377, 1229, 1158, 1023, 898, 852, 767, 729 cmÀ1; el-
emental analysis calcd (%) for C40H55LaNO2PSi: C 61.61, H 7.11, N 1.80;
found: C 61.63, H 8.18, N 1.98.
AHCTREUNG
ACHTREUNG
3
4H; C6H4); 13C NMR (75 MHz, C6D6): d=22.3, 25.3, 43.0, 52.3 (d, JPC
=
3
1
2
35.3 Hz), 129.4 (d, JPC =6.8 Hz), 133.5 (d, JPC =15.5 Hz), 135.4 (d, JPC
=
20.4 Hz), 136.1, 151.3 ppm (d, 1JPC =31.5 Hz); 31P{1H} NMR (160 MHz,
A
N
G
À
C6D6): d=À21.1 ppm; IR (Nujol): n˜ =3431 (N H), 1599 (C=N), 1479,
1383, 1173, 1099, 1015, 818, 743 cmÀ1
HRMS: m/z: calcd for
C19H24Cl2N2P: 381.1054 [M+H]+; found: 381.1050.
iPrN=C{P(C6H3Cl2-3,5)2}(NHiPr) (3j): colorless solid, yield 95%;
1H NMR (300 MHz, C6D6): d=0.86 (d, J=6.6 Hz, 6H; CH
(CH3)2), 1.16
(d, J=6.0 Hz, 6H; CH(CH3)2), 3.37 (d, J=6.3 Hz, 1H; NH), 4.08–4.16
solution of 2-La (192mg, 0.292mmol) in THF (2mL) was treated with a
solution of diphenylphosphine (55 mg, 0.292 mmol) in THF (3 mL).
After stirring at room temperature for 5 h, the solvent was removed
under reduced pressure, and the residue was washed with hexane and
dried in vacuum at room temperature for 0.5 h to provide light yellow
powder. The light yellow powder was dissolved in benzene and reduced
under vacuum to precipitate 5 as light yellow crystalline powder (167 mg,
0.131 mmol, 90% yield). Complex 5 could also be obtained by recrystalli-
zation of 4 in benzene. Single crystals of 5·2C6H6 suitable for X-ray anal-
;
ACHTREUNG
AHCTREUNG
ACHTREUNG
(m, 2H; CH), 7.01 (s, 2H; C 6H3), 7.21 ppm (d, J=7.8 Hz, 4H; C6H3);
13C NMR (75 MHz, C6D6): d 22.1, 25.1, 43.3, 52.7 (d, 3JPC =37.1 Hz),
1
130.1, 131.7 (d, 2JPC =20.4 Hz), 136.2 (d, 3JPC =7.4 Hz), 138.4 (d, JPC
=
21.6 Hz), 149.2 ppm (d, 1JPC =32.8 Hz); 31P{1H} NMR (160 MHz, C6D6):
ysis were grown in benzene at room temperature for one week. H NMR
À
d=À18.1 ppm; IR (Nujol): n˜ =3436 (N H), 1604 (C=N), 1555, 1457,
(300 MHz, [D8]THF): d=0.27 (s, 12H; SiMe2), 2.06 (s, 6H; p-C6H2-
1378, 1135, 860, 799, 676 cmÀ1; HRMS: m/z: calcd for C19H22Cl4N2P:
AHCTREUNG
449.0275 [M+H]+; found: 449.0283.
A
ACHTREUNG
6.96 (m, 8H; C6H5), 7.23–7.28 ppm (m, 8H; C6H5); 13C NMR (75 MHz,
[D8]THF): d=5.2, 11.3, 14.2, 19.7, 20.5, 107.0, 122.1, 124.6, 126.4, 127.8
(d, 3JPC =5.0 Hz), 128.0, 128.1, 130.0, 130.3 (d, 2JPC =17.3 Hz), 149.3 (d,
1JPC =41.4 Hz), 151.4 ppm; 31P{1H} NMR (160 MHz, [D8]THF): d=
8.53 ppm (brs); IR (Nujol): n˜ =2951, 2922, 2852, 1572, 1462, 1377, 1298,
1227, 1157, 1024, 899, 831, 764, 706 cmÀ1; elemental analysis calcd (%)
for C64H78La2N2P2Si2: C 60.47, H 6.18, N 2.20; found: C 60.90, H 6.40, N
2.42.
1
iPrN=C{P
(400 MHz, C6D6): d=0.90 (d, J=6.0 Hz, 6H; CH
6.4 Hz, 6H; CH(CH3)2), 3.42(d, J=6.8 Hz, 1H; NH), 4.23–4.29 (m, 2H;
CH), 7.01 (dd, J=8.4 Hz, J=6.8 Hz, 4H; C6H4), 7.15 ppm (d, J=8.4 Hz,
G
U
(CH3)2), 1.22 (d, J=
4H; C6H4); 13C NMR (100 MHz, C6D6): d=22.5, 25.5, 43.2, 52.5 (d, JPC
=
3
1
36.3 Hz), 124.4, 132.3 (d, JPC =6.6 Hz), 134.0 (d, JPC =15.7 Hz), 135.5 (d,
2JPC =20.6 Hz), 151.1 ppm (d, 1JPC =32.1 Hz); 31P{1H} NMR (160 MHz,
À
C6D6): d À21.2 ppm; IR (Nujol): n˜ =3421 (N H), 1601 (C=N), 1462,
1378,
1173,
1068,
1010,
814,
725 cmÀ1
;
HRMS:
A
(C5Me4)(NC6H2Me3-2,4,6)}La
U
U
U
m/z: calcd for C19H2479Br2N2P: 469.0044 [M+H]+; found: 469.0052.
iPrN=C(PEtPh)
(NHiPr) (3l): colorless liquid, yield, 86%; 1H NMR
(400 MHz, C6D6): d=0.94 (d, J=6.4 Hz, 3H; CH(CH3)2), 0.99 (d, J=
(CH3)2), 1.01–1.17 (m, 3H; CH2CH3), 1.27 (d, J=6.0 Hz,
glovebox, a solution of 2-La (185 mg, 0.282 mmol) in THF (2 mL) was
treated with a solution of diphenylphosphine (52mg, 0.282mmol) in
THF (3 mL). After stirring at room temperature for 5 h, N,N’-diisopro-
pylcarbodiimide (36 mg, 0.282 mmol) was added to the above reaction
A
ACHTREUNG
AHCTREUNG
6.8 Hz, 3H; CH
ACHTREUNG
2176
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Chem. Eur. J. 2008, 14, 2167 – 2179

Rare-Earth Metal Catalyst Precursors
FULL PAPER
mixture. After 5 h, the solvent was removed under reduced pressure, and
the residue was extracted with hexane followed by filtering to give a
clean solution. The solution volume was reduced under vacuum to pre-
cipitate 6 as light yellow crystalline powder (219 mg, 0.262 mmol, 93%
yield). 1H NMR (400 MHz, C6D6): d=0.68 (d, J=6.4 Hz, 12H; CH-
mixture. After 5 h, the solvent was removed under reduced pressure, and
the residue was extracted with hexane/ether followed by filtering to give
a clean solution. The solution volume was reduced under vacuum to pre-
cipitate 7 as light yellow crystalline powder (212 mg, 0.254 mmol, 90%
yield). 7 could also be obtained by recrystallization of 6 in ether. Single
crystals of 7·0.5hexane suitable for X-ray analysis were grown in hexane/
ether at room temperature for 2days. 1H NMR (400 MHz, C6D6): d=
ACHTREUNG
A
ACHTREUNG
AHCTREUNG
0.68 (d, J=6.4 Hz, 12H; CH
7.2Hz, 3H; CH 3 (hexane)), 0.96 (t, J=7.2Hz, 6H; CH 3 (ether)), 1.23–
1.27 (m, 4H; CH2 (hexane)), 2.07 (s, 6H; o-C6H2(CH3)3), 2.31 (s, 3H; p-
C6H2(CH3)3), 2.47 (s, 6H; C5Me4), 2.50 (s, 6H; C5Me4), 3.16 (q, J=
7.2Hz, 4H; CH 2 (ether)), 4.04–4.11 (m, 2H; CH(CH3)2), 7.02(s, 2H;
C6H2
C
7.02(s, 2H; C 6H2(CH3)3), 7.05–7.08 (m, 2H; C6H5), 7.12–7.16 (m, 4H;
C
12.4, 14.5, 21.1, 21.7, 25.6, 26.1, 50.4 (d, 3JPC =21.5 Hz), 68.6, 109.1, 124.0,
AHCTREUNG
2
127.1, 128.0, 128.6 (d, 3JPC =5.8 Hz), 128.7, 129.3, 130.6, 132.2 (d, JPC
=
18.9 Hz), 136.0 (d, 1JPC =20.7 Hz), 151.2, 171.0 ppm (d, 1JPC =59.3 Hz);
31P{1H} NMR (160 MHz, C6D6): d=À17.3 ppm; IR (Nujol): n˜ =2955,
2924, 2853, 1584, 1459, 1438, 1377, 1357, 1331, 1298, 1233, 1177, 1005,
892, 766, 708 cmÀ1; elemental analysis calcd (%) for C43H61LaN3OPSi
C46H70LaN3OPSi: C 61.93, H 7.37, N 5.04; found: C 61.60, H 7.58, N 4.81.
A
124.0, 127.1, 128.0, 128.6 (d, 3JPC =5.8 Hz), 128.7, 129.3, 130.6, 132.2 (d,
1
2JPC =18.9 Hz), 136.0 (d, 1JPC =20.7 Hz), 151.2, 171.0 ppm (d, JPC
=
A
(C5Me4)(NC6H2Me3-2,4,6)}La
U
U
U
59.3 Hz); 31P{1H} NMR (160 MHz, C6D6): d=À17.3 ppm; IR (Nujol): n˜ =
the glovebox, a solution of 2-La (185 mg, 0.282 mmol) in THF (2 mL)
was treated with a solution of diphenylphosphine (52mg, 0.282mmol) in
THF (3 mL). After stirring at room temperature for 5 h, N,N’-diisopro-
pylcarbodiimide (36 mg, 0.282 mmol) was added to the above reaction
2955, 2924, 2854, 1584, 1459, 1438, 1376, 1357, 1331, 1298, 1233, 1176,
1005, 893, 766, 707 cmÀ1
;
elemental analysis calcd (%) for
C46H70LaN3OPSi: C 62.85, H 8.03, N 4.78; found: C 63.20, H 7.66, N 4.71.
Table 4. Crystallographic data and structure refinement details for 2-Ln (Ln: La, Pr, Nd, Sm, Gd, Lu, Y, and Sc).
2-La
2-Pr
2-Nd
2-Sm
formula
Mw
C33H49LaN2OSi
656.74
C33H49N2OPrSi
658.74
C33H49N2NdOSi
662.07
C33H49N2OSiSm
668.18
crystal system
space group
a [Š]
b [Š]
c [Š]
monoclinic
P2(1)/n
8.7539(6)
18.0371(12)
20.3696(13)
92.0520(10)
3214.2(4)
4
1.357
1.393
1360
1.51–26.018
18050
monoclinic
P2(1)/n
8.7244(11)
17.969(2)
20.404(3)
92.054(2)
3196.7(7)
4
1.369
1.588
1368
1.51–25.078
13923
monoclinic
P2(1)/n
8.7016(14)
17.918(3)
20.392(3)
91.935(2)
3177.5(9)
4
1.384
1.698
13721380
1.51–25.038
15087
monoclinic
P2(1)/n
8.6635(19)
17.891(4)
20.430(5)
92.027(3)
3164.7(12)
4
b [8]
V [Š3]
Z
1calcd [gcmÀ3
]
1.402
1.920
m [mmÀ1
(000)
q range [8]
]
F
A
1.99–25.128
12622
no. of reflns collected
no. of indep reflns
no. of variables
GOF
R [I>2s(I)]
Rw
63025460
354
1.005
0.0285
0.0414
5614
354
1.035
0.0261
0.0599
5500
354
0.9820.980
0.0289
354
0.0384
0.0877
0.0416
2-Gd
2-Lu
2-Y
2-Sc
formula
Mw
C33H49GdN2OSi
675.08
C33H49LuN2OSi
692.80
C33H49N2OSiY
606.74
C29H41N2ScSi
490.69
crystal system
space group
a [Š]
b [Š]
c [Š]
monoclinic
P2(1)/n
8.6251(17)
17.800(3)
20.426(4)
91.861(3)
3134.3(11)
4
1.431
2.181
1388
1.52–25.088
1483217331 64
5536
354
1.070
orthorhombic
P2(1)2(1)2(1)
11.0631(13)
15.2989(18)
18.893(2)
90
3197.8(6)
4
1.439
3.151
1416
1.71–26.51
152 14436
6546
monoclinic
P2(1)/n
8.6019(13)
17.748(3)
20.434(3)
92.061(2)
3117.6(8)
4
1.293
1.936
1288
1.52–26.578
monoclinic
P2(1)/n
8.5252(5)
15.5402(10)
21.2446(13)
90.7630(10)
2814.3(3)
4
1.158
0.322
1056
1.62–25.028
b [8]
V [Š3]
Z
1calcd [gcmÀ3
]
m [mmÀ1
(000)
q range [8]
]
F
A
no. of reflns collected
no. of indep reflns
no. of variables
GOF
R [I>2s(I)]
Rw
6423
354
1.008
0.0377
0.1074
4945
309
1.085
0.0376
343
1.025
0.0346
0.06620.0751
0.0626
0.1066
Chem. Eur. J. 2008, 14, 2167 – 2179
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2177

Z. Hou et al.
Table 5. Crystallographic data and structure refinement details for 4, 5, and 7.
4
5·2C6H6
7·0.5hexane
formula
Mw
crystal system
space group
a [Š]
b [Š]
c [Š]
a [8]
b [8]
C40H55LaNO2PSi
779.82142 879.02
orthorhombic
P2(1)2(1)2(1)
9.5999(8)
19.8229(17)
20.5705(18)
90
C76H90La2N2P2Si2
C46H70LaN3OPSi
7.44
triclinic
triclinic
¯
¯
P1
P1
12.010(4)
13.258(5)
13.476(5)
106.340(4)
102.167(4)
114.506(4)
1736.9(10)
1
1.365
1.336
73292
1.70–26.538
8311
10.9764(8)
11.5061(8)
21.0458(15)
96.0770(10)
101.0430(10)
115.4280(10)
2302.4(3)
2
90
90
g [8]
V [Š3]
Z
3914.5(6)
4
1.323
1calcd [gcmÀ3
]
1.268
1.024
m [mmÀ1
(000)
q range [8]
]
1.195
F
A
1616
2
1.43–25.018
20353
6835
424
0.640
2.01–26.538
13565
9238
no. of reflns collected
no. of indep reflns
no. of variables
GOF
R [I>2s(I)]
Rw
6509
388
0.9920.990
0.03620.0350
0.0549
479
0.0387
0.0444
0.0871
X-ray crystallographic studies: Crystals for X-ray analyses of 2-Ln (Ln:
La, Pr, Nd, Sm, Gd, Lu, Y, and Sc), 4, 5, and 7 were obtained as de-
scribed in the preparations. The crystals were manipulated in the glove-
box and were sealed in thin-walled glass capillaries. Data collections
were performed at À1008C on a Bruker CCD APEX diffractometer with
a CCD area detector, using graphite-monochromated MoKa radiation
(l=0.71069 Š). The determination of crystal class and unit cell parame-
ters was carried out by the SMART program package. The raw frame
data were processed using SAINT and SADABS to yield the reflection
data file.[17] These structures were solved by use of SHELXTL pro-
gram.[18] Refinement was performed on F2 anisotropically for all the non-
hydrogen atoms by the full-matrix least-squares method. The hydrogen
atoms were placed at the calculated positions and were included in the
structure calculation without further refinement of the parameters. Crys-
tal data, data collection and processing parameters for compounds 2-Ln
(Ln: La, Pr, Nd, Sm, Gd, Lu, Y, and Sc), 4, 5, and 7 are summarized in
Table 4 and Table 5. Crystallographic data (excluding structure factors)
have been deposited with the Cambridge Crystallographic Data Centre
as supplementary publication nos. CCDC 658060 (2-La), 658063 (2-Pr),
658062( 2-Nd), 658065 (2-Sm), 658059 (2-Gd), 658061 (2-Lu), 658066 (2-
Y), 658064 (2-Sc), 658067 (4), 658068 (5·2C6H6), and 658069
(7·0.5hexane). These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
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This work was partly supported by a Grant-in-Aid for Scientific Research
on Priority Areas (No. 18065020, “Chemistry of Concerto Catalysis”)
from the Ministry of Education, Culture, Sports, Science and Technology
of Japan, a Grant-in-Aid for Scientific Research (A) (No. 18205010)
from the Japanese Society for the Promotion of Science, and the National
Natural Science Foundation of China (No. 20328201).
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Received: August 22, 2007
Published online: December 14, 2007
Chem. Eur. J. 2008, 14, 2167 – 2179
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2179