Bis(phosphinimino)methanides as ligands in divalent lanthanide and alkaline earth chemistry - Synthesis, structure, and catalysis

Article abstract of DOI:10.1016/j.jorganchem.2005.03.023

Divalent bis(phosphinimino)methanide lanthanide complexes of composition [{(Me₃SiNPPh₂)₂CH}EuI(THF)]₂ and [{(Me₃SiNPPh₂)₂CH}YbI(THF)₂] have been prepared by a salt metathesis reactions of K{CH(PPh₂NSiMe ₃)₂} and LnI₂. Further reactions of these complexes with [K(THF)_nN(PPh₂)₂] led selectively to the heteroleptic amido complexes [{(Me₃SiNPPh ₂)₂CH}Ln{(Ph₂P)₂N}(THF)] (Ln = Eu, Yb). The ytterbium complex can also be obtained by reduction of [{CH(PPh ₂NSiMe₃)₂}Yb{(Ph₂P)₂N}Cl] with elemental potassium. The single crystals of [{(Me₃SiNPPh ₂)₂CH}Ln{(Ph₂P)₂N}(THF)] contain enantiomerically pure complexes. As a result of the similar ionic radii of the divalent lanthanides and the heavier alkaline earth metals some similarities in coordination chemistry of the bis(phosphinimino)methanide ligand were anticipated. Therefore, MI₂ (M = Ca, Sr, Ba) was reacted with K{CH(PPh₂NSiMe₃)₂} to give [{(Me ₃SiNPPh₂)₂CH}CaI(THF)₂], [{(Me ₃SiNPPh₂)₂CH}SrI(THF)]₂, and [{(Me₃SiNPPh₂)₂CH}BaI(THF)₂] ₂, respectively. As expected the Sr and Eu complexes and the Ca and Yb complexes are very similar, whereas for the Ba compound, as a result of the large ion radius, a different coordination sphere is observed. For all new complexes the solid-state structures were established by single crystal X-ray diffraction. In the solid-state the {CH(PPh₂NSiMe₃) ₂}^- ligand acts as tridentate donor forming a long methanide carbon metal bond. Thus, all complexes presented can be considered as organometallic compounds. [{(Me₃SiNPPh₂) ₂CH}YbI(THF)₂] was also used as precatalyst for the intramolecular hydroamination/cyclization reaction of different aminoalkynes and aminoolefines. Good yields but moderate activities were observed.

Full text of DOI:10.1016/j.jorganchem.2005.03.023

Journal of Organometallic Chemistry 690 (2005) 5078–5089
www.elsevier.com/locate/jorganchem
Bis(phosphinimino)methanides as ligands in divalent lanthanide
and alkaline earth chemistry – synthesis, structure, and catalysis
*
Tarun K. Panda, Agustino Zulys, Michael T. Gamer, Peter W. Roesky
Institut fu¨r Chemie, Freie Universita¨t Berlin Fabeckstrasse 34-36, 14195 Berlin, Germany
Received 21 January 2005; received in revised form 16 March 2005; accepted 16 March 2005
Available online 5 May 2005
Dedicated to Professor Herbert Schumann on the occasion of his 70th birthday
Abstract
Divalent bis(phosphinimino)methanide lanthanide complexes of composition [{(Me3SiNPPh2)2CH}EuI(THF)]2 and [{(Me3SiN-
PPh2)2CH}YbI(THF)2] have been prepared by a salt metathesis reactions of K{CH(PPh2NSiMe3)2} and LnI2. Further reactions of
these complexes with [K(THF)nN(PPh2)2] led selectively to the heteroleptic amido complexes [{(Me3SiNPPh2)2CH}Ln{(Ph2P)2N}-
(THF)] (Ln = Eu, Yb). The ytterbium complex can also be obtained by reduction of [{CH(PPh2NSiMe3)2}Yb{(Ph2P)2N}Cl] with
elemental potassium. The single crystals of [{(Me3SiNPPh2)2CH}Ln{(Ph2P)2N}(THF)] contain enantiomerically pure complexes.
As a result of the similar ionic radii of the divalent lanthanides and the heavier alkaline earth metals some similarities in coordination
chemistry of the bis(phosphinimino)methanide ligand were anticipated. Therefore, MI2 (M = Ca, Sr, Ba) was reacted with
K{CH(PPh2NSiMe3)2} to give [{(Me3SiNPPh2)2CH}CaI(THF)2], [{(Me3SiNPPh2)2CH}SrI(THF)]2, and [{(Me3SiNPPh2)2CH}-
BaI(THF)2]2, respectively. As expected the Sr and Eu complexes and the Ca and Yb complexes are very similar, whereas for
the Ba compound, as a result of the large ion radius, a different coordination sphere is observed. For all new complexes the solid-state
structures were established by single crystal X-ray diffraction. In the solid-state the {CH(PPh2NSiMe3)2}ꢀ ligand acts as tridentate
donor forming a long methanide carbon metal bond. Thus, all complexes presented can be considered as organometallic compounds.
[{(Me3SiNPPh2)2CH}YbI(THF)2] was also used as precatalyst for the intramolecular hydroamination/cyclization reaction of different
aminoalkynes and aminoolefines. Good yields but moderate activities were observed.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Alkaline earth metals; Bis(phosphinimino)methanides; Catalysis; Hydroamination; Lanthanides; P,N ligands
1. Introduction
amido-metal chemistry to produce well-defined reaction
centers in transition metal complexes. In this way, the
reactivity of the resulting early transition metal com-
pounds can be specifically tailored to allow applications
in areas such as the activation of small poorly reactive
molecules, homogeneous catalysis, or organic synthesis
[1,2]. One synthetic approach among others is the use of
P–N ligands such as phosphoraneiminate, phosphini-
mines, and phosphinimides in main group and transition
metal chemistry [3–8]. Recently, the deprotonated deriva-
tives of the well-known bis(phosphinimine), CH2(PPh2N-
SiMe3)2 [9] have drawn the attention of a number of
research groups. It was shown that a monoanionic
In the last 15 years, enormous progress has been ob-
served in the design and application of amido-metal
chemistry of the early transition metals. In the early stages
of this area cyclopentadienyl-analogous amido ligands
were studied for comparison with and for further investi-
gations of the well-known cyclopentadienyl moiety.
Today, the stable amido-metal bond is utilized in
*
Corresponding author. Tel.: +49 (0) 308 385 4004; fax: +49 (0) 308
385 2440.
E-mail address: roesky@chemie.fu-berlin.de (P.W. Roesky).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.03.023

T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
5079
[10–13], and a dianionic species [14,15] ({CH(PPh2-
NSiMe3)2}ꢀ and {C(PPh2NSiMe3)2}2ꢀ, respectively)
can be generated by deprotonation of the precursor
CH2(PPh2NSiMe3)2. The monoanionic species was used
as a ligand in main group and transition metal chemistry,
[16–19], whereas the dianionic ligand was reported by
Cavell and co-workers [17,20] to form carbene like com-
plexes with a series of transition metals and samarium.
Recently, we introduced the monoanionic phosphinimine
{CH(PPh2NSiMe3)2}ꢀ, into yttrium and lanthanide
chemistry. We have previously reported the synthesis of
a series of lanthanide bis(phosphinimino)methanide
dichloride complexes including yttrium, [{CH(PPh2NSi-
Me3)2LnCl2]2 (Ln = Y, Sm, Dy, Er, Yb, Lu) [21]. These
compounds were obtained by the reaction of K{CH-
(PPh2NSiMe3)2} [12], with the corresponding yttrium or
lanthanide trichlorides. Furthermore, reactions with the
[{CH(PPh2NSiMe3)2}LnCl2]2 compounds have led to
the corresponding amido complexes, [{CH(PPh2NSi-
Me3)2}Ln(NPh2)2] (Ln = Y, Sm) [21], diphosphinoam-
ido complexes, [{CH(PPh2NSiMe3)2}Ln{(Ph2P)2N}Cl]
(Ln = Y, La, Nd, Yb) [22], cyclopentadienyl complexes,
[{CH(PPh2NSiMe3)2}Ln(g5-C5H5)2] (Ln = Y, Sm, Er)
[23], and cyclooctatetraene bis(phosphinimino) metha-
nide complexes, [{CH(PPh2NSiMe3)2}Ln(g8-C8H8)]
(Ln = Y, Sm, Er, Yb, Lu) [24], which have been reported
by us. These derivatives were used as homogenous cata-
lysts for a number of different catalytic applications.
Thus, [{CH(PPh2NSiMe3)2}Ln{(Ph2P)2N}Cl] are active
catalysts for the ring-opening polymerization of e-capro-
lactone and the polymerization of methyl methacrylate,
whereas [{CH(PPh2NSiMe3)2}Ln(g8-C8H8)] was used
as catalysts for the hydroamination/cyclization reaction.
In all lanthanide compounds we reported so far with,
{CH(PPh2NSiMe3)2}ꢀ tends to show an uncommon
coordination mode. In the solid-state structures the
methine carbon atom coordinates via a long interaction
on to the metal atom. Thus, the six membered metalla-
cycle (N1–P1–C1–P2–N2–Ln), which is formed by che-
lation of the two trimethlysilylimine groups to the
metal center, adopts a pseudo-boat conformation
(Scheme 1). In one case the interaction between the
methine carbon atom and the metal atom was also ob-
served in solution. By using yttrium as metal center,
divalent lanthanides and to the heavier alkaline earth
metals. It is well known that the divalent lanthanides
and the heavier alkaline earth metals exhibit similar
ion radii, thus comparable coordination chemistry can
be applied. Currently in this field, there are limited re-
lated complexes containing the mesityl substituted
bis(phosphinimino)methanide,
{CH(PPh2N-Mes)2}ꢀ
ligand in the coordination sphere, which have been
reported by Hill et al. [25]. Best to our knowledge in this
area one Sm(II) complex, [Sm{CH(PPh2N-Mes)2}2], the
related Ba compound [Ba{CH(PPh2N-Mes)2}2], and the
amido compounds [{CH(PPh2N-Mes)2}2MN(SiMe3)2]
(M = Ca, Sr) are the only known compounds.
In this contribution, we present a full account of the
reaction of LnI2 (Ln = Eu, Yb) and MI2 (M = Ca, Sr,
Ba) with K{CH(PPh2NSiMe3)2} as well as some further
reactions of the obtained mono iodine compounds.
Additionally the application of the ytterbium iodine
complex as a catalyst in the hydroamination/cyclization
is reported.
2. Results and discussion
2.1. Lanthanide iodine complexes
Reaction of K{CH(PPh2NSiMe3)2} (1) with ytter-
bium and europium diiodide in a 1:1 molar ratio in
THF afforded the corresponding divalent lanthanide
complexes [{(Me3SiNPPh2)2CH}EuI(THF)]2 (2a) and
[{(Me3SiNPPh2)2CH}YbI(THF)2] (2b) as crystals in
good yields (Scheme 2) [26]. The potassium reagent 1,
which was described earlier [12] was used as starting
material to avoid coordination of lighter alkali halides
such as lithium chloride. The new complexes have been
characterized by standard analytical/spectroscopic tech-
niques, and the solid-state structures of both compounds
were established by single crystal X-ray diffraction.
The signal of the methine proton (d 1.91) in 1H NMR
spectrum of the diamagnetic ytterbium compound (2b)
is in the range of comparable trivalent lanthanide com-
plexes ([{CH(PPh2NSiMe3)2}YCl2]2 (d 1.93)) but shows
2
1J(C,Y) and a J(H,Y) coupling was reported. These
Si
Si
N
Eu
observations were also supported by DFT calculations
[21]. Thus, this class of compounds can be considered
as organometallic compounds. Motivated by these re-
sults we were interested to extend our studies on to the
THF
I
P
P
N
N
P
P
Ln = Eu
Eu
0.5
I
N
THF
Si
Si
Si
K
P
P
N
N
THF
- KI
+ LnI2
(2a)
Si
N
Si
P
THF
Ln = Yb
Yb I
THF
M
P
N
(1)
P
P
N
N
Si
(2b)
Scheme 1.
Scheme 2.

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T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
a slight downfield shift compared to 1 (d 1.58). The sig-
nals of the phenyl protons are broadened in the 1H
NMR spectrum. Complex 2b shows a sharp signal in
the 31P{1H} NMR spectrum (d 14.2) shifted downfield
by about 10 ppm relative to the trivalent yttrium com-
plex [{CH(PPh2NSiMe3)2}YCl2]2 (d 20.4), showing that
the phosphorus atoms in each case are chemically equiv-
alent in solution. Beside the sharp signal small satellite
signals are observed, which are caused by coupling of
171Yb with the phosphorus atoms.
bis(phosphinimino)methanide ligand, which was ob-
served earlier (see above). Best to our knowledge only
five structural characterized Eu(II)–C r-carbon bonds
were reported so far [27,28] of which only one is a
Eu(II)–CH bond (Eu–C 265(1) pm) [28]. The distance
of the latter is significantly shorter than the distance be-
tween the central carbon atom (C1) and the europium
atom (Eu–C1 294.5(2) pm) in 2a. The geometry of the
{CH(PPh2NSiMe3)2}ꢀ ligand is as expected.
Compound 2b crystallizes in the triclinic space group
ꢀ
The structures of 2a,b were confirmed by single crys-
tal X-ray diffraction in the solid-state. As a result of the
different ionic radii 2a forms a dimer in the solid-state
whereas 2b is monomeric. In 2a, which crystallizes in
the monoclinic space group P21/c the metal centers of
the dimeric complexes are asymmetrically bridged by
two l-iodine atoms (Eu–I 330.93(5) pm, Eu–I0
335.24(6) pm) (Fig. 1). Rectangular through the center
of the Eu–I–Eu0–I0 plane, a crystallographic C2 axis is
observed. The bis(phosphinimino)methanide ligand
forms a six membered metallacycle (N1–P1–C1–P2–
N2–Eu) by chelation of the two trimethlysilylimine
groups to the lanthanide metal. The Eu–N distances
are Eu–N1 259.6(2) pm and Eu–N2 256.3(2) pm show-
ing an almost symmetric attachment of the ligand onto
the metal center. The metallacycle adopts a twist boat
conformation, in which the central carbon atom and
the europium atom are displaced from the N2P2 least-
square-plane. The displacement depends on the metal
center and also on the packing in the solid-state [22].
The Eu atom is displaced by 158 pm and the methine
carbon atom (C1) about 67 pm out of plane. The inter-
action between the methine carbon atom and the euro-
pium atom results in a tridentate coordination of the
P1 with two molecules in the unit cell (Fig. 2). In contrast
to 2a, compound 2b is monomeric in the solid-state. If
the bis(phosphinimino)methanide ligand is considered
as a tridentate donor the ytterbium center is six-coordi-
nated. As observed for 2a a six membered metallacycle
(N1–P1–C1–P2–N2–Yb), which adopts a twist boat con-
formation is formed by the {CH(PPh2NSiMe3)2}ꢀ
ligand and the yttrium atom. The Yb atom is displaced
by 159 pm and the methine carbon atoms (C1) about
72 pm out of plane. The distance of the central carbon
atom C1 and the ytterbium atom (Yb–C1 270.0(4) pm)
is significantly longer than usual Yb(II)–C distances
[29] (e.g., 256(1) pm in [(C5Me5)2Yb{CH(SiMe3)2}(C5-
Me5)K]n] [28]) however the folding of the six membered
ring towards the ytterbium atom is caused by a weak
Fig. 1. Solid-state structure of 2a showing the atom labeling scheme,
omitting hydrogen atoms. Selected bond lengths (pm) or angles (ꢁ):
Eu–I 330.93(5), Eu–I0 335.24(6), Eu–N1 259.6(2), Eu–N2 256.3(2), Eu–
C1 294.5(2), Eu–O1 247.9(2), P1–N1 158.2(2), P2–N2 158.6(2); Eu–I–
Eu0 99.213(7), I–Eu–I0 80.787(7), I–Eu–N1 132.23(5), I–Eu–N2
98.49(5), I–Eu–C1 157.99(4), I–Eu–O1 96.19(6), I0–Eu–N2 168.00(5),
I0–Eu–N1 98.21(5), I0–Eu–C1 119.08(4), I0–Eu–O1 81.25(7), N1–Eu–
N2 91.14(7), N1–Eu–C1 58.53(6), N1–Eu–O1 131.14(8), N2–Eu–C1
60.04(6), N2–Eu–O1 86.94(8), C1–Eu–O1 78.98(8), P1–C1–P2
126.88(15).
Fig. 2. Solid-state structure of 2b showing the atom labeling scheme,
omitting hydrogen atoms. Selected bond lengths (pm) or angles (ꢁ):
Yb–I 305.86(6), Yb–N1 249.1(4), Yb–N2 247.5(3), Yb–C1 270.0(4),
Yb–O1 246.6(4), Yb–O2 249.1(4), P1–N1 158.7(3), P2–N2 158.3(3),
C1–P1 172.7(4), C1–P2 173.9(4); I–Yb–N1 108.37(7), I–Yb–N2
107.98(7), I–Yb–C1 165.91(8), I–Yb–O1 94.21(9), I–Yb–O2 92.94(9),
N1–Yb–N2 92.36(11), N1–Yb–C1 62.84(11), N1–Yb–O1 154.85(13),
N1–Yb–O2 91.17(14), N2–Yb–C1 63.29(10), N2–Yb–O1 90.99(13),
N2–Yb–O1 76.38(15), C1–Yb–O1 96.90(12), C1–Yb–O2 98.06(12),
O1–Yb–O2 76.38(15), P(1)–C(1)–P(2) 124.9(2).

T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
5081
interaction. The geometry of the coordination polyhe-
dron can be considered as strongly distorted octahedron
having bond angles of I–Yb–O1 94.21(9)ꢁ, I–Yb–
O2 92.94(9)ꢁ, N1–Yb–N2 92.36(11)ꢁ, N1–Yb–O2
91.17(14)ꢁ, N2–Yb–O1 90.99(13)ꢁ, and O1–Yb–O2
76.38(15)ꢁ.
By recrystallizing from THF/n-pentane (1:2) single
crystals of 3a,b can be obtained. The solid-state struc-
tures of both 3a and 3b were established by single crystal
X-ray diffraction (Fig. 3). Compounds 3a,b crystallize in
the orthorhombic space group P212121 with four mole-
cules in the unit cell. Since 3a,b are chiral molecules,
which crystallize in a chiral space group, the single crys-
tals of 3a,b contain enantiomerically pure complexes.
For both enantiomers the solid-state structure was deter-
mined by single crystal X-ray diffraction (Fig. 3). The
chirality in 3a,b is not caused by the arrangement of
the ligands around the metal center but by the folding
of the THF molecule and the {(Ph2P)2N}ꢀ ligand rela-
tive to the C1–Ln axis (Fig. 3). Obviously the observed
chirality is thus a solid-state effect only. The coordina-
tion polyhedra of 3a,b are formed by the {CH(PPh2N-
SiMe3)2}ꢀ ligand, the g2-{(Ph2P)2N}ꢀ ligand and one
THF molecule. Thus, the lanthanide atom is six-coordi-
nated if the {CH(PPh2NSiMe3)2}ꢀ ligand is considered
as tridentate donor. As observed for 2a,b a six membered
ring (N1–P1–C1–P2–N2–Ln), adopts a twist boat con-
formation, which is formed by the {CH(PPh2NSiMe3)2}ꢀ
ligand and the lanthanide atom. The displacement of the
Ln and C1 atoms out of the N2P2 least-square-plane are
Eu 126 pm, Yb 116 pm and C1 63 pm (3a) and 65 pm
(3b). The distance of the central carbon atom C1 and
the lanthanide atom (287.8(4) pm (3a), 278.6(4) pm
(3b)) is in the range observed for 2a,b (Ln–C1
2.2. Lanthanide amido complexes
When Hill et al. reported the synthesis of the homo-
leptic complex [Sm{CH(PPh2N-Mes)2}2], which was ob-
tained by a transamination of the neutral ligand
({CH2(PPh2N-Mes)2}) with [Sm{N(SiMe3)2}2], they
were unable to isolate any heteroleptic compound such
as [Sm{CH(PPh2N-Mes)2}{N(SiMe3)2}]. To obtain
bis(phosphinimino)methanide amido complexes of the
divalent lanthanides we used compounds 2a,b as starting
material. As amido ligand we employed the flexible
{(Ph2P)2N}ꢀ ligand, which recently was introduced by
us into lanthanide chemistry [30–32].
Reaction of [K(THF)nN(PPh2)2] with 2a,b in THF in
a 1:1 molar ratio led selectively to the amido complexes
of composition [{(Me3SiNPPh2)2CH}Ln{(Ph2P)2N}
(THF)] (Ln = Eu (3a), Yb (3b)) (Scheme 2) [26]. In a dif-
ferent approach compound 3b was also obtained by
reduction of the recently reported trivalent complex
[{CH(PPh2NSiMe3)2}Yb{(Ph2P)2N}Cl]
elemental potassium in refluxing THF (Scheme 3) [26].
[22]
with
Si
Si
P N
THF
I
N P
N P
0.5
Eu
Eu
I
P N
THF
Si
Si
P
P
N
(2a)
K(THF)
Si
P N
O
n
or
Ln
- KI
P
P N
Si
N
Si
P N
P
THF
Yb
I
THF
P N
Si
Ln = Eu (3a), Yb (3b)
(2b)
Si
P N
Cl
K/ THF
- KCl
Yb
P
P N
Si
N
P
Scheme 3.

5082
T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
mide ligand in 3a,b is g2-coordinated via the nitrogen
and one phosphorus atom. Thus, one of the phosphorus
atoms of the ligand binds to the lanthanide center,
whereas the other phosphorus atom is bent away. The
Ln–N3 and Ln–P3 bond lengths are 252.7(4) and
306.54(13) pm (3a) and 241.2(3) and 294.96(11) pm
(3b). The free electron pair of the non-bonded phospho-
rus atom points away from the lanthanide center. Within
the ligand the P–N bond distance varies slightly.
The multinuclear NMR data of the diamagnetic com-
pound 3b is consistent with the solid-state structure. The
1H NMR spectrum of compound 3b shows a character-
istic sharp singlets of the Me3Si groups. The signal of the
methine protons in 3b is overlapped when deuterated
THF is used as the solvent. Whereas using C6D6 as a
solvent, only a broad peak is observed (d 1.91 ppm).
1
The phenyl region in the H NMR spectrum is as ex-
pected. More characteristic is the 31P{1H} NMR spec-
trum. Complex 3b shows two sharp signals in the
31P{1H} NMR spectrum (d 19.8, 49.2 ppm), indicating
that the phosphorus atoms of each ligand are chemically
equivalent in solution at room temperature. The dy-
namic behavior of the {(Ph2P)2N}ꢀ ligand was also ob-
served in all other lanthanide complexes reported so far
[22,31–33]. Furthermore small satellite signals caused by
2J(Yb,P) coupling are observed.
2.3. Alkaline earth iodine complexes
It is well established that the reactivity and coordina-
tion behavior of the divalent lanthanide metals and the
heavier alkaline earth metals is somewhat similar [34].
This similarity in coordination chemistry originates
from the similar ion radii (for CN 6 (pm): Ca2+ 100,
Yb2+ 102, Sr2+ 118, Eu2+ 117, Ba2+ 135) [35]. Therefore,
we expected a certain relationship between 2a and an
analogues strontium(II) compound and between 2b
and a related calcium(II) compound, whereas barium(II)
is too large to be part of this analogy. To prove our
expectations 1 was reacted with MI2 (M = Ca, Sr, Ba)
in THF at room temperature to give the corresponding
bis(phosphinimino)methanide complexes [{(Me3SiN-
PPh2)2CH}CaI(THF)2] (4), [{(Me3SiNPPh2)2CH}SrI-
(THF)]2 (5), and [{(Me3SiNPPh2)2CH}BaI(THF)2]2
(6), as crystalline solids in good yields (Scheme 4) [26].
The new complexes have been characterized by standard
analytical/spectroscopic techniques, and the solid-state
structures of all compounds were established by single
crystal X-ray diffraction (Figs. 4–6). As observed for
the divalent lanthanide compounds a six membered ring
(N1–P1–C1–P2–N2–M), which adopts a twist boat
conformation is formed by the {CH(PPh2NSiMe3)2}ꢀ
ligand and the alkaline earth metal atom. The expected
similarities between 2b and 4 as well as 2a and 5 are ob-
served in the solid-state. Thus, both pairs of compounds
have the same monomeric [{(Me3SiNPPh2)2CH}MI
Fig. 3. Solid-state structure of 3a (top) and 3b (bottom) showing the
atom labeling scheme, omitting hydrogen atoms. Selected bond lengths
(pm) or angles (ꢁ): 3a: Eu–N1 253.9(4), Eu–N2 257.9(4), Eu–N3
252.7(4), Eu–C1 287.8(4), Eu–P1 322.90(12), Eu–P2 325.06(12), Eu–P3
306.54(13), Eu–O 253.8(3), P1–N1 159.8(4), P1–C1 173.4(5), P2–N2
160.5(4), P2–C1 172.9(5); N1–Eu–N2 102.56(12), N1–Eu–N3
118.31(12), N2–Eu–N3 134.71(12), N3–Eu–C1 122.41(12), N1–Eu–P3
110.07(9), N2–Eu–P3 116.76(9), N3–Eu–P1 126.01(9), N3–Eu–P2
132.24(9), N3–Eu–P3 32.77(9), N1–Eu–O 90.70(11), N2–Eu–O
95.98(13), N3–Eu–O 101.85(12), C1–Eu–O 134.69(12), O–Eu–P3
134.62(9), P1–N1–Eu 100.1(2), P2–N2–Eu 99.3(2), P1–C1–P2
132.7(3), P3–N3–P4 121.2(2). 3b: Yb–N1 242.9(3), Yb–N2 246.0(3),
Yb–N3 241.2(3), Yb–C1 278.6(4), Yb–P1 312.15(11), Yb–P2
314.39(11), Yb–P3 294.96(11), Yb–O 242.9(2), P1–N1 160.2(3), P1–
C1 173.7(4), P2–N2 160.4(3), P2–C1 173.2(4); N1–Yb–N2 106.60(10),
N1–Yb–N3 119.99(10), N2–Yb–N3 130.93(10), N3–Yb–C1
124.06(12), N1–Yb–P3 112.41(8), N2–Yb–P3 114.62(8), N3–Yb–P1
128.88(8), N3–Yb–P2 132.35(8), N3–Yb–P3 34.43(8), N1–Yb–O
90.41(9), N2–Yb–O 93.45(12), N3–Yb–O 100.41(11).
294.5(2) pm (2a), 270.0(4) pm (2b)). As seen in other
diphosphanylamide complexes of the lanthanides, e.g.,
in [{(Ph2P)2N}LnCl2(THF)3] [31] the diphosphanyla-

T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
5083
Si
P N
THF
Ca I
THF
M = Ca
P N
Si
(4)
Si
Si
N
Si
K
THF
P
N P
N P
P N
P N
I
M = Sr
THF
- KI
Sr
Si
Sr
+ MI2
0.5
I
P
N
THF
(5)
Si
Si
(1)
Si
THF THF
N
Si
P
N P
N P
I
M = Ba
Ba
Ba
0.5
I
P
N
THF
THF
Si
Si
(6)
Scheme 4.
ꢀ
(THF)2] (2b and 4) and dimeric composition [{(Me3SiN-
PPh2)2CH}MI(THF)]2 (2a and 5), respectively. On the
other hand 2b and 4 crystallize in different Laue groups.
Compound 2b crystallizes in the triclinic space group P1
with two molecules in the unit cell (Fig. 2), whereas
compound 4 crystallizes in the monoclinic space group
P21/n with four molecules of 4 and four molecules of
non-coordinated THF in the unit cell.
Even Yb(II) and Ca(II) have almost the same ionic ra-
dii, the bond distances and angles within 2b and 4 are dif-
ferent. Thus the N1–M–N2 bite angle in 4 (88.8(2)ꢁ) is
smaller than the corresponding angle in 2a (92.36(11)ꢁ)
and the M–N bond distances in 4 (Ca–N1 250.2(5) pm
and Ca–N2 241.1(5) pm) differ from those in 2b (Yb–
N1 249.1(4) pm, Yb–N2 247.5(3) pm), respectively. It is
observed in compound 4 that the {CH(PPh2NSiMe3)2}ꢀ
Fig. 4. Solid-state structure of 4 showing the atom labeling scheme,
omitting hydrogen atoms. Selected bond lengths (pm) or angles (ꢁ):
Ca–I 313.53(13), Ca–N1 250.2(5), Ca–N2 241.1(5), Ca–C1 273.5(6),
Ca–O1 241.3(5), Ca–O2 239.3(5), P1–N1 159.0(5), P2–N2 159.0(5),
C1–P1 173.1(6), C1–P2 174.4(6); I–Ca–N1 124.93(11), I–Ca–N2
103.28(12), I–Ca–C1 166.80(13), I–Ca–O1 92.25(12), I–Ca–O2
87.04(13), N1–Ca–N2 88.8(2), N1–Ca–C1 61.9(2), N1–Ca–O1
141.9(2), N1–Ca–O2 90.2(2), N2–Ca–C1 64.3(2), N2–Ca–O1 90.3(2),
N2–Ca–O2 168.0(2), C1–Ca–O1 83.7(2), C1–Ca–O2 104.9(2), O1–Ca–
O2 83.1(2), P1–C1–P2 122.8(3).
Fig. 5. Solid-state structure of 5 showing the atom labeling scheme,
omitting hydrogen atoms. Selected bond lengths (pm) or angles (ꢁ): I–
Sr 331.02(6), I0–Sr 334.34(7), Sr–N1 260.1(2), Sr–N2 256.6(2), Sr–C1
295.8(3), Sr–O1 247.4(2), P1–N1 157.8(2), P2–N2 158.7(2); Sr–I–Sr0
98.493(9), I–Sr–I0 81.507(9), I–Sr–N1 132.08(5), I–Sr–N2 98.58(5), I–
Sr–C1 157.93(5), I–Sr–O1 94.73(7), I0–Sr–N1 97.17(5), I0–Sr–N2
169.27(6), I0–Sr–C1 118.81(5), I0–Sr–O1 81.73(7), N1–Sr–N2
90.74(8), N1–Sr–C1 58.24(7), N1–Sr–O1 132.75(8), N2–Sr–C1
59.80(7), N2–Sr–O1 87.58(9), C1–Sr–O1 80.85(9), P1–C1–P2 126.7(2).

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T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
l-iodine atoms (Ba–I 351.77(6), Ba–I0 361.26(6)). Rect-
angular through the center of the Ba–I–Ba0–I0 plane, a
crystallographic C2 axis is observed. In contrast to the
isostructural compounds 2a and 5 in 6 an additional
molecule of THF is coordinated to the barium atom.
By considering the {CH(PPh2NSiMe3)2}ꢀ ligand as tri-
dentate donor the barium atom is seven-coordinated.
The increased coordination number of the barium atom
is a result of the larger ion radius. As observed for the
previous discussed complexes, the bis(phosphini-
mino)methanide ligand forms a six membered metalla-
cycle (N1–P1–C1–P2–N2–Ba), which adopts a twist
boat conformation having a Ba–C1 interaction of
312.7(3) pm. The Ba atom is displaced by 199 pm and
the methine carbon atom (C1) about 68 pm out of the
N2P2 least-square-plane. Interestingly, in the related
di(bis(phosphinimino)methanide) complex [Ba{CH-
(PPh2N-Mes)2}2], no carbon barium bond is observed
[25]. In the latter complex the ligand acts only as a
bidentate donor. Surprisingly, no complex of composi-
tion [{CH(PPh2N-Mes)2}BaX] could be isolated so far.
The Ba–N and Ba–O distances in compound 6 are
Ba–N1 286.6(3) pm, Ba–N2 278.4(2) pm, Ba–O1
280.6(3) pm, and Ba–O2 275.7(3) pm. As a result of
the larger coordination number in compound 6 com-
pared to 4 and 5, the N–M–N bite angle is diminished
(N1–M–N2: 88.8(2)ꢁ (4), 90.74(8)ꢁ (5), 79.30(7)ꢁ (6)).
The bond distances and angles within the {CH(PPh2-
NSiMe3)2}ꢀ ligand are as expected.
Fig. 6. Solid-state structure of 6 showing the atom labeling scheme,
omitting hydrogen atoms. Selected bond lengths (pm) or angles (ꢁ): Ba–I
351.77(6), Ba–I0 361.26(6), Ba–N1 286.6(3), Ba–N2 278.4(2), Ba–C1
312.7(3), Ba–O1 280.6(3), Ba–O2 275.7(3), P1–N1 157.6(3), P2–N2
158.4(3); I–Ba–I0 78.064(10), Ba–I–Ba0 101.936(10), I–Ba–N1 117.58(5),
I–Ba–N2 98.76(5), I–Ba–C1 152.87(5), I–Ba–O1 79.88(6), I–Ba–O2
130.22(6), I0–Ba–N1 89.29(5), I0–Ba–N2 165.18(5), I0–Ba–C1 123.87(5),
I0–Ba–O1 109.38(6), I0–Ba–O2 77.81(7), N1–Ba–N2 79.30(7), N1–Ba–
C1 53.86(7), N1–Ba–O1 157.36(7), N1–Ba–O2 104.94(8), N2–Ba–C1
55.75(7), N2–Ba–O1 84.00(8), N2–Ba–O2 114.12(8), C1–Ba–O1
103.90(8), C1–Ba–O2 74.28(8), P1–C1–P2 124.8(2).
ligand is slightly asymmetrically attached to the metal
center. Thus, the deviations in bond distances and angles
between 2b and 4 seem to be result of the crystal packing
in the different space groups. The distance of the central
carbon atom C1 and the calcium atom in 4 (Ca–C1
273.5(6) pm) is in the range of the corresponding Ca–C
bond observed in [{CH(PPh2N-Mes)2}2CaN(SiMe3)2]
(271.3(7) pm) [25]. The displacement of the Ca and C1
atom out of the N2P2 least-square-plane are 166 pm
and 71 pm. Bond distances and angles within the
{CH(PPh2NSiMe3)2}ꢀ ligand are as expected.
In contrast to the pair 2b and 4 compounds 2a and 5
are isostructural to each other. Both crystallize as dimeric
compounds in the monoclinic space group P21/c. Thus
the metal centers of the dimeric complexes are asymmet-
rically bridged by two l-iodine atoms (Sr–I 331.02(6) pm,
Sr–I0 334.34(7) pm) (Fig. 5). Rectangular through the
center of the Sr–I–Sr0–I0 plane, a crystallographic C2 axis
is observed. The interaction between the methine carbon
atom (C1) and the strontium atom (295.8(3) pm), which
is longer than usual Sr–C distances is in the range of
the related bond in [{CH(PPh2N-Mes)2}CaN(SiMe3)2]
(286.1(2) pm) [25]. As observed for 2a the metal atom is
displaced by 158 pm and the methine carbon atom (C1)
about 67 pm out of the N2P2 least-square-plane.
Beside the solid-state structures compounds 4, 5, and 6
1
were also investigated in solution by H and 31P{1H}
NMR methods. The spectra are consistent with time aver-
aged mirror symmetric structures in solution. No reorga-
nization of the coordination sphere is necessary to explain
the dynamic behavior. The signal of the methine proton
1
(d 1.88 (4), 1.95 (5), 1.34 (6)) in H NMR spectra of all
alkaline earth metal compounds is in the range of
K{CH(PPh2NSiMe3)2} (d 1.58) [12]. The phenyl region
1
in the H NMR spectra is as expected. Complex 4, 5,
and 6 each show a sharp signal in the 31P{1H} NMR spec-
trum (d 18.7 (4), 17.9 (5), 16.1 (6)), which are in the range
of the alkali metal salts Li(THF){CH(PPh2NSiMe3)2} (d
17.6) and K{CH-(PPh2NSiMe3)2} (d 13.0) [12]. These
observations show that the phosphorus atoms in each
case are chemically equivalent in solution.
2.4. Hydroamination/cyclization catalysis
The mechanism of the lanthanide metallocene cata-
lyzed hydroamination/cyclization reaction was some
years ago established by Marks et al. [36]. In the initial
step of this mechanism a leaving group (R) on the metal-
locene precatalyst, [(C5Me5)2Ln-R], is replaced by the
substrate. Alternatively, it was shown that the divalent
samarocens [(C5Me5)2Sm] and [(C5Me5)2Sm(THF)2]
catalyze the hydroamination/cyclization of a variety of
As expected the barium compound 6 (Fig. 6) has no
structural analogues in divalent lanthanide chemistry.
Compound 6 crystallizes in the monoclinic space group
P21/n having two molecules in the unit cell. As observed
for 2a and 5 compound 6 is a dimeric complex in which
the center metals are asymmetrically bridged by two

T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
5085
aminoolefins [37]. Mechanistic studies showed that the
active catalysts are trivalent complexes, which were gen-
erated by an in situ oxidation reaction of the samarocen
precatalyst. Based on these results we were interested in
studying the catalytic activity of the divalent ytterbium
complex 2b as precatalyst for the hydroamination/cycli-
zation reaction. The scope and the limitation by using 2b
as catalyst in the intramolecular hydroamination/cycli-
zation reaction were tested with different aminoalkynes
and aminoolefines. The results are summarized in Table
1. The reaction scope is limited so far on five membered
rings formation. The rigorously anaerobic reactions of
the catalysts with dry, degassed aminoolefins and amin-
oalkynes proceeds regiospecifically (>95%) in benzene.
The two aminoalkynes, which were tested by us were
converted to the cyclic product at elevated temperature
in quantitative yields (entries 1–6). At room temperature
a sluggish activity is observed only (entry 7). In contrast
aminoolefines could be reacted only if they have geminal
rigid substituents in b-position to the amino group
(Thorpe–Ingold-effect) [38] (entries 8 and 9). Kinetic
of the metallocene catalysts. During the initiation of
the catalysis a color change from red to yellow is ob-
served, indicating an in situ oxidation reaction of 2b.
3. Summary
Divalent bis(phosphinimino)methanide lanthanide
complexes of composition [{(Me3SiNPPh2)2CH}EuI-
(THF)]2 (2a) and [{(Me3SiNPPh2)2CH}YbI(THF)2]
(2b) have been prepared by a salt metathesis reaction
of K{CH(PPh2NSiMe3)2} and LnI2. The structures of
both compounds were confirmed by single crystal X-
ray diffraction in the solid-state. As a result of the differ-
ent ion radii [{(Me3SiNPPh2)2CH}EuI(THF)]2 forms a
dimer in the solid-state whereas [{(Me3SiNPPh2)2-
CH}YbI(THF)2] is monomeric. Reaction of [K(THF)n-
N(PPh2)2] with 2a,b in THF in a 1:1 molar ratio led
selectively to the amido complexes of composition
[{(Me3SiNPPh2)2CH}Ln{(Ph2P)2N}(THF)] (Ln = Eu
(3a), Yb (3b)). In an alternative approach, compound
3b was also obtained by reduction of the recently
reported trivalent complex [{CH(PPh2NSiMe3)2}Yb-
{(Ph2P)2N}Cl] with elemental potassium in refluxing
THF. The single crystals of 3a,b contain enantiomeri-
cally pure complexes.
1
studies were undertaken by in situ H NMR spectros-
copy. The reaction of a 20-fold molar excess of the
substrates were monitored with constant catalyst con-
centration until complete substrate consumption. The
decrease of the substrate peak was integrated versus
the product signals. Kinetics data of the cyclization of
5-phenyl-4-pentyn-1-amine indicates a zero order kinetic
in substrate concentration, in an analogy to the results
To probe the well established similarity in reactivity
and coordination chemistry between the divalent lantha-
nide metals and the heavier alkaline earth metals for the
bis(phosphinimino)methanide ligand, MI2 (M = Ca, Sr,
Ba) was reacted with K{CH(PPh2NSiMe3)2} to give
Table 1
Hydroamination/cyclization reaction of terminal aminoolefines and
alkynes using 2b as catalysta
[{(Me3SiNPPh2)2CH}CaI(THF)2],
[{(Me3SiNPPh2)2-
CH}SrI(THF)]2, and[{(Me3SiNPPh2)2CH}BaI(THF)2]2.
As expected the Sr and Eu complexes as well as the Ca
and Yb complexes are very similar whereas for the Ba
compound as a result of the large ion radius a different
coordination sphere, in which the barium atom is seven-
coordinated, is observed.
For all new complexes the solid-state structures were
established by single crystal X-ray diffraction. The crys-
tal structures of these complexes show that the methine
carbon atom is bound to the lanthanide atom. Thus, all
complexes presented in this paper can be considered as
organometallic compounds. Finally, [{(Me3SiNPPh2)2-
CH}YbI(THF)2] was also used as precatalyst for the
intramolecular hydroamination/cyclization reaction of
different aminoalkynes and aminoolefines. Good yields
but moderate activities were observed.
Entry
Substrate
Product
Cat.
mol% ˚C
T
Yield
%
T
h
TOF
h-1
b)
Ph
Ph
1
2
3
4
5
6
7
8
5.3
5.3
5.3
2.8
2.8
1.4
2.8
5.1
120
> 95
> 95
6
3.15
H2N
N
90
60
18 1.05
80 108 0.14
H
120
60
> 95
> 95
3
11.9
N
H2N
56 0.63
60
60 192c) 0.22
RT
120
17
92
96 0.06
96 0.19
H
N
NH2
9
NH2
H
N
120
−
120
4. Experimental
4.1. General
a
Condition, cat 20 mg (0.028 mM), C6D6.
Calculated by 1H NMR.
b
c
All manipulations of air-sensitive materials were
performed with the rigorous exclusion of oxygen and
Cat 10 mg (0.014 mM).

5086
T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
moisture in flame-dried Schlenk-type glassware either on
a dual manifold Schlenk line, interfaced to a high vac-
uum (10ꢀ4 Torr) line, or in an argon-filled M. Braun
glove box. Ether solvents (THF and ethyl ether) were
predried over Na wire and distilled under nitrogen from
K (THF) or Na wire (ethyl ether) as well as benzophe-
none ketyl prior to use. Hydrocarbon solvents (toluene
and n-pentane) were distilled under nitrogen from
LiAlH4. All solvents for vacuum line manipulations were
stored in vacuo over LiAlH4 in resealable flasks. Deuter-
ated solvents were obtained from Chemotrade Chemi-
ehandelsgesellschaft mbH (all P99 atom % D) and
were degassed, dried, and stored in vacuo over Na/K
alloy in resealable flasks. NMR spectra were recorded
on a Jeol JNM-LA 400 FT NMR spectrometer. Chemi-
cal shifts are referenced to internal solvent resonances
and are reported relative to tetramethylsilane and 85%
phosphoric acid (31P NMR), respectively. IR spectra
were obtained on a Shimadzu FTIR-8400s. Elemental
analyses were carried out with an Elementar vario EL.
YbCl3 [39], EuI2 [40], YbI2 [41], [K(THF)nN(PPh2)2]
(n = 1.25, 1.5) [30] and K{CH(PPh2NSiMe3)2} [12] were
prepared according to literature procedures.
was filtered and the filtrate was concentrated to 5 ml.
Pentane (10 ml) was layered on the top of the THF solu-
tion. After one day red crystals were obtained.
Yield: 402 mg (80%). IR (KBr [cmꢀ1]): 3055 (m,
m(C@CAH)), 2948 (m, m(C–H)), 2889 (w), 1589 (s,
m(C@C)), 1483 (m), 1436 (s), 1244 (m), 1159 (s), 1114
(br), 1068 (s), 832 (s), 782 (s), 745 (br), 692 (s), 648 (s),
1
552 (s), 506 (s). H NMR (C6D6, 400 MHz, 25 ꢁC): d
0.44 (s, 18H, SiMe3), 1.52 (br, 8H, THF), 1.91 (br,
1H, CH), 3.8 (br, 8H, THF), 6.96 (br, 12H, Ph), 7.74
(br, 8H, Ph). 31P{H} NMR (C6D6, 161.70 MHz,
25 ꢁC):
d
14.2 (2J(P,Yb) = 66.4 Hz). C39H55IP2Si2-
N2O2Yb (1001.94) Calc.: C 46.75, H 5.53, N 2.80.
Found: C 45.21, H 4.60, N 2.78.
4.4. [{(Me3SiNPPh2)2CH}Eu{(Ph2P)2N}(THF)]
(3a)
300 mg (0.5 mmol) of 1 and 275 mg (0.5 mmol) of Eu-
I2(THF)2 was taken in a 25 ml flask inside the glove box.
15 ml of THF was condensed at ꢀ196 ꢁC onto the mix-
ture. The reaction mixture was stirred at room tempera-
ture for 16 h. The THF was evaporated under vacuo and
250 mg (0.5 mmol) of [K(THF)nN(PPh2)2] was added to
the reaction vessel. To this mixture 15 ml of THF was
condensed at ꢀ196 ꢁC. The solution was stirred at room
temperature for 18 h. The solution was filtered to re-
move the potassium iodide and the filtrate was concen-
trated to 5 ml. Pentane (10 ml) was layered on top of
the THF solution. After one day orange crystals were
obtained.
Yield: 330 mg (57%). IR (KBr [cmꢀ1]): 3053 (m,
m(C@CAH)), 2949 (m, m(C–H)), 2891 (w), 1577 (s,
m(C@C)), 1482 (m), 1434 (s), 1242 (m), 1120 (br), 1027
(s), 954 (br), 829 (s), 739 (s), 594 (s), 5553 (m).
C59H67EuN3OP4Si2 (1166.23) Calc.: C 60.76, H 5.79,
N 3.60. Found: C 59.41, H 5.68, N 3.47.
4.2. Synthesis of [{(Me3SiNPPh2)2CH}EuI(THF)]2
(2a)
300 mg (0.5 mmol) of 1 and 275 mg (0.5 mmol) of
EuI2(THF)2 was taken together under an inert atmo-
sphere. 15 ml of THF was condensed onto it at
ꢀ196 ꢁC. The solution mixture was allowed to warm
to room temperature and kept under stirring for
16 h. During the reaction, the solution turned to deep
yellow color with white precipitate formed. The reac-
tion mixture was filtered and the filtrate was concen-
trated to 5 ml. Pentane (10 ml) was layered on the
top of the THF solution. After one day yellow crys-
tals were obtained.
Yield: 310 mg (65%). IR (KBr [cmꢀ1]): 3055 (m,
m(C@CAH)), 2947 (m, m(C–H)), 2891 (br), 1589 (s,
m(C@C)), 1483 (m), 1435 (s), 1245 (m), 1113 (br), 1059
(s), 1027 (s), 950 (br), 832 (br), 742 (m), 709 (s), 693
(s), 661 (s), 554 (s), 515 (s). C70H94Eu2I2N4O2P4Si4
(1881.55) Calc.: C 46.26, H 5.21, N 3.08. Found: C
45.96, H 5.40, N 2.94.
4.5. [{(Me3SiNPPh2)2CH}Yb{(Ph2P)2N}(THF)]
(3b)
Route A. 3b can be obtained in an analogues way to
3a (Yield 325 mg (55%)).
Route B. A mixture of 300 mg (0.5 mmol) [{(Me3SiN-
PPh2)2CH}K], 140 mg (0.5 mmol) YbCl3 and 250 mg
(0.5 mmol) [K(THF)nN(PPh2)2] was taken under inert
atmosphere. To this mixture 15 ml of THF was con-
densed at ꢀ196 ꢁC. The solution was stirred at room
temperature for 18 h. Then THF was evaporated under
vacuo. 19.5 mg (0.5 mmol) of potassium was added to
the reaction vessel. Further 15 ml of THF was intro-
duced and refluxed for another 16 h. THF was removed
under vacuo and 20 ml of toluene was added. The com-
pound was extracted by filtration and then washed with
pentane. The title compound was crystallized from
THF/pentane (1:2).
4.3. [{(Me3SiNPPh2)2CH}YbI(THF)2] (2b)
300 mg (0.5 mmol) of 1 and 286 mg (0.5 mmol) of
YbI2(THF)2 was taken together under an inert atmo-
sphere. 15 ml of THF was condensed onto it at
ꢀ196 ꢁC. The solution mixture was allowed to warm
to room temperature and kept under stirring for 16 h.
During the reaction, the solution turned to deep red col-
or and a white precipitate formed. The reaction mixture

T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
5087
Yield: 250 mg (42%) dark red crystals. IR (KBr
[cmꢀ1]): 3053 (m, m(C@CAH)), 2949 (m, m(C–H)), 2891
(w), 1577 (s, m(C@C)), 1476 (m), 1434 (s), 1242 (m),
1112 (br), 1027 (m, m(PC)), 937 (m), 831 (s), 739 (s),
C39H55BaIN2P2Si2 (822.02) (6 ꢀ 2THF) Calc.: C 45.30,
H 4.78, N 3.41. Found: C 45.79, H 5.27, N 2.87.
4.7. General procedure for the hydroamination reaction
(NMR scale reaction)
1
715 (m), 694 (s). H NMR (d8-THF, 400 MHz, 20 ꢁC):
ꢀ0.23 (s, 18H, SiMe3), 1.75 (br, 5H, THF + CH), 3.61
(br, 4H, THF), 6.93–7.10 (m, 20H, Ph), 7.15–7.27 (m,
Compound 2b was weighed under argon gas into an
NMR tube. C6D6 (ꢁ0.7 ml) was condensed into the
NMR tube, and the mixture was frozen to ꢀ196 ꢁC.
The reactant was injected onto the solid mixture, and
the whole sample was melted and mixed just before the
insertion into the core of the NMR machine (t0). The
ratio between the reactant and the product was exactly
calculated by comparison of the integration of the corre-
sponding signals.
1
4H, Ph), 7.37–7.52 (m, 16H, Ph), 7.86 (br, 4H, Ph). H
NMR (C6D6, 400 MHz, 20 ꢁC): d 0.13 (s, 18H, SiMe3),
1.39 (br, 4H, THF), 1.91 (br, 1H, CH), 3.70 (br, 4H,
THF), 6.62–7.11 (m, 24H, Ph), 7.41–7.60 (m, 8H, Ph),
7.74–7.86 (m, 8H, Ph). 31P{1H} NMR (C6D6,
161.7 MHz, 20 ꢁC): d 17.2 (PCP), 46.7 (PNP). 13C{1H}
NMR (d8-THF, 100.4 MHz, 20 ꢁC): d 4.4 (SiMe3),
26.4 (b, THF + CH), 68.2 (s, THF), 127.5 (s, Ph),
128.0 (s, Ph), 128.4 (m, Ph), 130.5 (s, Ph), 132.3 (m,
Ph), 133.2 (m, Ph), 138.1 (d, Ph), 147.9 (dd, Ph).
31P{1H} NMR (d8-THF, 161.7 MHz, 20 ꢁC): d 19.8
(PCP) (2J(P,Yb) = 62 Hz), 49.2 (PNP) (2J(P,Yb) =
53 Hz). C59H67N3OP4Si2Yb (1187.30) Calc.: C 59.69,
H 5.69, N 3.54. Found: C 59.75, H 5.63, N 3.42.
4.8. X-ray crystallographic studies of 2a,b, 3a,b, 4, 5
and 6
Crystals of 2a,b, 3a,b, 4, 5 and 6 were grown from a
THF/pentane (1:2). Suitable crystals were coated in min-
eral oil (Aldrich) and mounted on glass fibers. The crystal
was transferred directly to the ꢀ100 ꢁC cold stream of a
Bruker SMART 1000 or a STOE IPDS 2T diffractometer
with Mo Ka radiation. Structures were solved using
SHELXS-97 [42] and refined against F2 using SHELXL-97 [43].
2a: C74H102Eu2I2N4O3P4Si4 (2aÆTHF), monoclinic,
P21/c (No. 14); lattice constants a = 1953.4(4) pm,
b = 995.8(2) pm, c = 2329.9(4) pm, b = 112.649(4)ꢁ, V =
4.6. [{(Me3 SiNPPh2)2CH}CaI(THF)2] (4),
[{(Me3SiNPPh2)2CH}SrI(THF)]2 (5),
[{(Me3SiNPPh2)2CH}BaI(THF)2]2 (6)
General procedure. 300 mg (0.5 mmol) of 1 and
0.5 mmol of MI2 was taken together under an inert
atmosphere. 15 ml of THF was condensed onto it. The
solution mixture was allowed to warm at room temper-
ature and kept under stirring for 16 h. During the reac-
tion a white precipitate formed. The reaction mixture
was filtered to remove potassium iodide and the filtrate
was concentrated to 5 ml. Pentane (10 ml) was layered
on the top of the THF solution. After one day colorless
crystals were obtained.
4182.7(13) · 106 pm3, Z = 2; l(Mo Ka) = 2.402 mmꢀ1
max. = 30.58; 12708 [Rint = 0.0221] independent reflec-
tions measured, of which 10,384 were considered ob-
;
h
served with I > 2r(I); max. residual electron density
; 405 parameters, R1(I >
1.121 and ꢀ1.119 e Aꢀ3
2r(I)) = 0.0268; wR2(all data) = 0.0793.
ꢀ
2b: C39H55IN2O2P2Si2Yb, triclinic, P1 (No. 2);
lattice constants a = 1027.2(2) pm, b = 1197.8(2) pm,
c = 1899.5(3) pm, a = 98.833(4)ꢁ, b = 90.468(4)ꢁ, c =
110.059(3)ꢁ, V = 2164.6(6) · 106 pm3, Z = 2; l(Mo
Ka) = 3.036 mmꢀ1; hmax. = 30.54; 12985 [Rint = 0.1125]
independent reflections measured, of which 10,681 were
considered observed with I > 2r(I); max. residual elec-
tron density 3.328 and ꢀ3.015 e Aꢀ3; 428 parameters,
R1(I > 2r(I)) = 0.0534; wR2(all data) = 0.1500.
1
4: Yield: 350 mg (74%) H NMR (C6D6, 400 MHz,
25 ꢁC): d 0.45 (s, 18H, SiMe3), 1.34 (t, 8H, THF), 1.88
(br, 1H, CH), 3.27 (t, 8H, THF), 6.94–7.15 (m, 12H,
o-, p-Ph), 7.65–7.72 (m, 8H, m-Ph). 31P{H} NMR
(C6D6, 161.70 MHz, 25 ꢁC): d 18.7. C35H47CaIP2Si2-
N2O2 (812.87) (4 ꢀ THF) Calc.: C 51.72, H 5.83, N
3.45. Found: C 51.51, H 6.28, N 3.02.
5: Yield: 320 mg (73%) 1H NMR (d8-THF, 400 MHz,
25 ꢁC): d 0.14 (s, 18H, SiMe3), 1.59 (br, 1H, CH), 1.74–
1.79 (m, 4H, THF), 3.58–3.62 (m, 4H, THF), 7.15–7.35
(m, 12H, o-, p-Ph), 7.58–7.70 (m, 8H, m-Ph). 31P{H}
3a: C59H67EuN3OP4Si2, orthorhombic, P212121 (No.
19);
lattice
constants
a = 1080.3(2) pm,
b =
2177.7(4) pm, c = 2422.7(4) pm, V = 5699(2) · 106 pm3,
Z = 4; l(Mo Ka) = 1.296 mmꢀ1; hmax. = 30.57; 17416
[Rint = 0.0784] independent reflections measured, of
which 12,788 were considered observed with I > 2r(I);
NMR (d8-THF, 161.70 MHz, 25 ꢁC):
d
17.9.
C62H78N4I2P4Si4Sr2 (1546.60) (5 ꢀ 2THF) Calc.: C
48.15, H 5.08, N 3.62. Found: C 47.42, H 5.54, N 2.99.
6: Yield: 420 mg (87%) 1H NMR (d8-THF, 400 MHz,
25 ꢁC): d 0.06 (s, 18H, SiMe3), 1.34 (br, 1H, CH), 1.72–
1.79 (m, 8H, THF), 3.56–3.62 (m, 8H, THF), 7.13–7.35
(m, 12H, o-, p-Ph), 7.52–7.70 (m, 8H, m-Ph). 31P{H}
max. residual electron density 2.653 and ꢀ1.195 e Aꢀ3
;
637 parameters, Flack parameter ꢀ0.045(10),
R1(I > 2r(I)) = 0.0473; wR2(all data) = 0.1166.
3b: C59H67N3OP4Si2Yb, orthorhombic, P212121 (No.
NMR (d8-THF, 161.70 MHz, 25 ꢁC):
d
16.1.
19);
lattice
constants
a = 1076.6(2) pm,
b =

5088
T.K. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 5078–5089
2158.1(5) pm, c = 2439.9(5) pm, V = 5669(2) · 106 pm3,
Z = 4; l(Mo Ka) = 1.847 mmꢀ1; hmax. = 30.61; 17335
[Rint = 0.0718] independent reflections measured, of
which 13,513 were considered observed with I > 2r(I);
G.J.P. Britovsek, V.C. Gibson, D.F. Wass, Angew. Chem., Int.
Ed. 38 (1999) 428–447, and references therein.
[2] R. Kempe, Angew. Chem. 112 (2000) 478–504;
R. Kempe, Angew. Chem., Int. Ed. 39 (2000) 468–493, and
references therein.
max. residual electron density 1.209 and ꢀ1.279 e Aꢀ3
;
[3] K. Dehnicke, F. Weller, Coord. Chem. Rev. 158 (1997) 103–169.
[4] K. Dehnicke, M. Krieger, W. Massa, Coord. Chem. Rev. 182
(1999) 19–65.
637
parameters,
Flack
parameter
ꢀ0.052(5),
R1(I > 2r(I)) = 0.0393; wR2(all data) = 0.0736.
4: C43H63CaIN2O3P2Si2 (4 THF), monoclinic, P21/n
(No. 14); lattice constants a = 1194.7(2) pm,
b = 1516.9(3) pm, c = 2636.7(5) pm, b = 101.25(3)ꢁ,
V = 4687(2) · 106 pm3, Z = 4; l(Mo Ka) = 0.950 mmꢀ1
max. = 29.26; 12,686 [Rint = 0.0588] independent reflec-
[5] D. Fenske, B. Maczek, K. Maczek, Z. Anorg. Allg. Chem. 623
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¨
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Plat, M.S. Eisen, J. Organomet. Chem. 604 (2000) 116–125.
[8] T.G. Wetzel, S. Dehnen, P.W. Roesky, Angew. Chem. 111 (1999)
1155–1158;
h
tions measured, of which 6975 were considered observed
with I > 2r(I); max. residual electron density 1.548 and
ꢀ0.880 e Aꢀ3; 472 parameters, R1(I > 2r(I)) = 0.0757;
wR2(all data) = 0.2399.
T.G. Wetzel, S. Dehnen, P.W. Roesky, Angew. Chem. Int. Ed. 38
(1999) 1086–1088.
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5: C74H102I2N4O3P4Si4Sr2 (5 THF), monoclinic, P21/c
(No. 14); lattice constants a = 1952.1(4) pm, b = 993.6(2)
pm, c = 2336.2(5) pm, b = 112.784(4)ꢁ, V = 4177.7(14) ·
106 pm3, Z = 2; l(Mo Ka) = 2.194 mmꢀ1; hmax. = 30.10;
12,177 [Rint = 0.0291] independent reflections measured,
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metallics 12 (1993) 1523–1536.
max. residual electron density 1.143 and ꢀ1.010 e Aꢀ3
;
405 parameters, R1(I > 2r(I)) = 0.0392; wR2(all data) =
0.1065.
6: C78H110Ba2I2N4O4P4Si4 monoclinic, P21/c (No. 14);
lattice constants a = 1183.8(2) pm, b = 2019.1(4) pm, c =
1886.7(4) pm, b = 98.375(4)ꢁ, V = 4461.5(15) · 106 pm3,
Z = 2; l(Mo Ka) = 1.740 mmꢀ1; hmax. = 30.56; 13,607
[Rint = 0.0291] independent reflections measured, of
which 10,057 were considered observed with I > 2r(I);
[12] M.T. Gamer, P.W. Roesky, Z. Anorg. Allg. Chem. 627 (2001)
877–881.
[13] R.P. Kamalesh Babu, K. Aparna, R. McDonald, R.G. Cavell,
Inorg. Chem. 39 (2000) 4981–4984.
[14] A. Kasani, R.P. Kamalesh Babu, R. McDonald, R.G. Cavell,
Angew. Chem. 111 (1999) 1580–1582;
max. residual electron density 1.518 and ꢀ1.668 e Aꢀ3
;
A. Kasani, R.P. Kamalesh Babu, R. McDonald, R.G. Cavell,
Angew. Chem. Int. Ed. 38 (1999) 1483–1484.
428 parameters, R1(I > 2r(I)) = 0.0376; wR2(all data) =
0.0859.
[15] C.M. Ong, D.W. Stephan, J. Am. Chem. Soc. 121 (1999) 2939–
2940.
[16] (a) C.M. Ong, P. McKarns, D.W. Stephan, Organometallics 18
(1999) 4197–4208;
5. Supplementary material
(b) P. Wei, D.W. Stephan, Organometallics 21 (2002) 1308–1310;
(c) P. Wei, D.W. Stephan, Organometallics 22 (2003) 601–604.
[17] (a) A. Kasani, R.P. Kamalesh Babu, R. McDonald, R.G. Cavell,
Organometallics 18 (1999) 3775–3777;
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC, Nos. 259915–259921. Copies of
this information may be obtained free of charge from
The Director, CCDC, 12, Union Road, Cambridge
CB2 1EZ [fax: +44(1223)336 033] or e-mail depos-
it@ccdc.cam.ac.uk or www.ccdc.cam.ac.uk.
(b) K. Aparna, R. McDonald, M. Fuerguson, R.G. Cavell,
Organometallics 18 (1999) 4241–4243.
[18] M.J. Sarsfield, M. Helliwell, D. Collison, Chem. Commun. (2002)
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(b) R.G. Cavell, R.P. Kamalesh Babu, A. Kasani, R. McDonald,
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Acknowledgment
(c) R.P. Kamalesh Babu, R. McDonald, R.G. Cavell, Chem.
Commun. (2000) 481–482;
This work was supported by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie.
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