Intramolecular lithium cation solvation in the "active ligand periphery" of a tripodal triaminostannate

Article abstract of DOI:10.1002/1099-0682(200208)2002:8<1968::AID-EJIC1968>3.0.CO;2-2

The tris(aminosilyl)methane derivative HC{SiMe₂NH(2-MeOC₆H₄)}₃ (1) was reacted with three molar equivalents of n-butyllithium in pentane to give the solvate-free trilithium triamide HC{SiMe₂N(Li)(2-MeOC₆H₄)}₃ (2) for which an X-ray diffraction study established the internal solvation of the lithium ions. The trilithium triamide 2 was converted to the triamidostannate [HC{SiMe₂N(2-MeOC₆H₄)}₃SnLi] (3) by treatment of 2 with one molar equivalent of SnCl₂. Both the NMR spectroscopic data obtained in solution and an X-ray structure analysis confirmed the intramolecular coordination of the lithium cation by the peripheral ortho-methoxy groups. Reaction of compound 3 with 0.5 molar equivalents of the dinuclear compound [Rh(COD)Cl]₂ in toluene afforded the mixed heterodimetallic complex [HC{SiMe₂N(2-MeOC₆H₄)}₃ Sn(Li)-Rh(η⁴-C₈H₁₂)(Cl)] (4), for which a doublet resonance at high field in the ¹¹⁹Sn NMR spectrum (δ= -196.3; ¹J_SnRh = 871.6 Hz) confirmed the formation of a Sn-Rh bond. The X-ray structure analysis revealed that the Rh centre in 4 adopts a slightly distorted, square-planar coordination mode, with a tin-rhodium bond length of 2.6048(4) A, and that the chloro ligand is additionally bonded to the lithium cation. ( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).

Full text of DOI:10.1002/1099-0682(200208)2002:8<1968::AID-EJIC1968>3.0.CO;2-2

FULL PAPER
Intramolecular Lithium Cation Solvation in the ‘‘Active Ligand Periphery’’
of a Tripodal Triaminostannate
Matthias Lutz,[b] Christian Galka,[a] Matti Haukka,[b] Tapani A. Pakkanen,*[b] and
Lutz H. Gade*[a]
Keywords: Tin / Lithium / N ligands / Metal-metal interactions / Rhodium
The tris(aminosilyl)methane derivative HC{SiMe2NH(2-
MeOC6H4)}3 (1) was reacted with three molar equivalents of
n-butyllithium in pentane to give the solvate-free trilithium
triamide HC{SiMe2N(Li)(2-MeOC6H4)}3 (2) for which an X-
ray diffraction study established the internal solvation of the
lithium ions. The trilithium triamide 2 was converted to the
triamidostannate [HC{SiMe2N(2-MeOC6H4)}3SnLi] (3) by
treatment of 2 with one molar equivalent of SnCl2. Both the
NMR spectroscopic data obtained in solution and an X-ray
structure analysis confirmed the intramolecular coordination
of the lithium cation by the peripheral ortho-methoxy groups.
Reaction of compound 3 with 0.5 molar equivalents of
the dinuclear compound [Rh(COD)Cl]2 in toluene afforded
the mixed heterodimetallic complex [HC{SiMe2N(2-
MeOC6H4)}3Sn(Li)−Rh(η4-C8H12)(Cl)] (4), for which a doublet
resonance at high field in the 119Sn NMR spectrum (δ =
1
−196.3; JSnRh = 871.6 Hz) confirmed the formation of a
Sn−Rh bond. The X-ray structure analysis revealed that the
Rh centre in 4 adopts a slightly distorted, square-planar coor-
dination mode, with a tin-rhodium bond length of 2.6048(4)
˚
A, and that the chloro ligand is additionally bonded to the
lithium cation.
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
separated salts (I) and contact ions have been found (Fig-
ure 1).[5] In the latter, the alkali metal ion is either bound
directly to the group 14 metal (II), in what is thought to
be primarily an ionic metal-metal bonding interaction, or
attached to the amido-N atoms in a bridging coordination
mode (III), thus breaking the overall threefold symmetry of
the system.
The structural chemistry and reactivity of neutral and an-
ionic tin(II) compounds has attracted much attention in re-
cent years.[1] Group 14 metal-amido and -imido derivatives,
in particular, have displayed a great variety of forms of ag-
gregation and reaction patterns.[2,3] The combination of
thermodynamic stabilization of the triamidometallates by
their integration into a rigid molecular cage structure along
with the well-defined orientation and high variability of the
peripheral N-substituents has established the tripodal tri-
amidometallates as a versatile new class of ligands in the
coordination chemistry of the transition metals.[4] The elec-
tronegative N-substituents at the divalent metal atoms
render them less oxidizable than would be expected for
alkyl- or aryl-substituted derivatives.
Figure 1. Different modes of cation-anion interactions in triamido-
stannates and their principal structural types
An interesting aspect of the structural chemistry of the
lithium triamidometallates in solution and in the solid state
is the type of interaction between the anionic cage and the
countercation (in most cases solvated Liϩ). Both solvent-
Which of the structural alternatives discussed above is
observed in a given case has been found to be largely unpre-
dictable. It was therefore thought that the design of an am-
ido tripod containing a specific binding site for the metal
cation in the ligand periphery would yield ‘‘ion pairs’’ of
predefined arrangement.
In an extension of our concept of the ‘‘active ligand peri-
phery’’ in polydentate amides[6,7] containing additional
donor functions for cation binding, we synthesised a tripod
with peripheral 2-anisyl groups. In this paper we report the
[a]
´
Laboratoire de Chimie Organometallique et de Catalyse
´
(CNRS UMR 7513), Institut Le Bel, Universite Louis Pasteur
Strasbourg,
4, rue Blaise Pascal, 67070 Strasbourg, France
Fax: (internat.) ϩ33-390/241-531
E-mail: gade@chimie.u-strasbg.fr
Department of Chemistry, University of Joensuu,
80101 Joensuu, Finland
Fax: (internat.) ϩ358-13/251-3344
E-mail: Tapani.Pakkanen@joensuu.fi
[b]
1968
 WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0808Ϫ1968 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 1968Ϫ1974

Lithium Cation Solvation in the “Active Ligand Periphery” of a Tripodal Triaminostannate
FULL PAPER
synthesis and crystallographic characterisation of the tri-
podal triamine, the corresponding trilithium triamide, and
its triaminostannate. The ‘‘ligand properties’’ of the latter
are demonstrated by the characterisation of a heterobi-
metallic rhodium complex containing this novel type of
stannate fragment.
Results and Discussion
Preparation and Crystallographic Studies of
HC{SiMe2NH(2-MeOC6H4)}3 (1) and the Lithium
Triamide HC{SiMe2N(Li)(2-MeOC6H4)}3 (2)
Figure 2. View of the molecular structure of 1; principal bond
˚
lengths (A) and angles (°): C(1)ϪSi(1) 1.8829(17), C(1)ϪSi(2)
1.8825(16), C(1)ϪSi(3) 1.8867(17), N(1)ϪSi(1) 1.7358(16),
N(2)ϪSi(2) 1.7439(14), N(3)ϪSi(3) 1.7395(15), N(1)ϪC(8)
[8]
Reaction of HC(SiMe2Br)3 in diethyl ether with three
molar equivalents of 2-methoxyaniline in the presence of
Et3N as auxiliary base yielded the triamine
HC{SiMe2NH(2-MeOC6H4)}3 (1) as a colourless solid
(Scheme 1).
1.394(2),
N(2)ϪC(15)
1.390(2),
N(3)ϪC(22)
1.394(2);
109.97(7),
129.96(14),
N(1)ϪSi(1)ϪC(1)
N(3)ϪSi(3)ϪC(1)
110.75(7), N(2)ϪSi(2)ϪC(1)
109.73(8), C(8)ϪN(1)ϪSi(1)
C(15)ϪN(2)ϪSi(2) 129.48(12), C(22)ϪN(3)ϪSi(3) 131.19(13)
Upon reaction of 1 with three molar equivalents of n-
butyllithium in pentane, the solvent-free trilithium triamide
HC{SiMe2N(Li)(2-MeOC6H4)}3 (2) was obtained as an ex-
tremely air- and moisture-sensitive compound (Scheme 1).
The signal patterns in the 1H, 13C, 29Si and 7Li NMR spec-
tra indicate a threefold symmetrical structure in solution
which does not appear to undergo dynamic processes on
the NMR time scale. The high molecular symmetry of the
trilithium salt 2 was also found in the single crystal X-ray
structure. The molecular structure is shown in Figure 3
along with the principal metric parameters.
Scheme 1
The spectroscopic and analytical data are consistent with
an effective threefold symmetry of 1 in solution. The low-
field shift of the apical CϪH proton resonance (δ ϭ 0.93
ppm in C6D6) which we observed previously for aryl-substi-
tuted tris(aminosilyl)methane derivatives[9] indicated a pre-
ferred conformation of the molecule in solution that is
inverted with respect to the adamantane-related arrange-
ment found for the corresponding alkyl-substituted derivat-
ives.[10] The peripheral groups of the ligand precursor are
thus effectively turned ‘‘inside-out’’. This type of molecular
structure is also prevalent in the solid state as was found in Figure 3. View of the molecular structure of 2; principal bond
˚
lengths (A) and angles (°): C(1)ϪSi(1) 1.904(2), C(1)ϪSi(2)
an X-ray diffraction study of the compound. The molecular
1.8902(19), C(1)ϪSi(3) 1.895(2), N(1)ϪSi(1) 1.7197(16),
structure of 1 is depicted in Figure 2 along with the prin-
cipal bond lengths and interbond angles. The main struc-
tural features resemble those of the previously characterised
triamine HC{SiMe2NH(4-CH3C6H4)}3, the three ortho-ani-
syl groups being very regularly arranged with the aromatic
rings in the same plane as the quasi-planar amine units and
the methoxy groups pointing outwards.
N(2)ϪSi(2) 1.7189(16), N(3)ϪSi(3) 1.7205(17), Li(1)ϪO(1)
1.963(4), Li(1)ϪN(1) 1.973(4), Li(1)ϪN(2) 1.997(4), Li(2)ϪO(3)
1.938(4), Li(2)ϪN(3) 2.000(4), Li(2)ϪN(1) 2.011(4), Li(3)ϪO(2)
1.915(4),
Li(3)ϪN(2)
1.976(4),
Li(3)ϪN(3)
1.992(4);
106.40(8),
93.98(17),
N(1)ϪSi(1)ϪC(1)
N(1)ϪSi(1)ϪC(1)
107.00(8),
106.39(8),
N(2)ϪSi(2)ϪC(1)
Li(1)ϪN(1)ϪLi(2)
Li(3)ϪN(2)ϪLi(1) 92.76(17), Li(3)ϪN(3)ϪLi(2) 85.70(18),
O(1)ϪLi(1)ϪN(1)
83.59(15),
O(3)ϪLi(2)ϪN(3)
83.54(15),
O(2)ϪLi(3)ϪN(2) 84.94(16)
Eur. J. Inorg. Chem. 2002, 1968Ϫ1974
1969

M. Lutz, C. Galka, M. Haukka, T. A. Pakkanen, L. H. Gade
FULL PAPER
The structural centrepiece is an adamantane-related het-
eroatom cage comprising three Li, N and Si atoms as well
as the carbon atom C(1) at the apex of the trisilylmethane
unit. This type of structural motif has been reported previ-
ously for a series of achiral[8,10] and C3-chiral[11] tripodal
lithium amides. The most remarkable feature is the internal
solvation of the lithium ions which generates a rare tris-
solvated lithium amide ring structure. The lithium atoms
themselves attain a highly nonsymmetrical coordination
geometry that is closer to a T-arrangement than to the con-
ventional trigonal structure. In spite of this unequal distri-
bution of the donor atoms, the lithium atoms are very sym-
`
metrically disposed vis-a-vis the negatively charged amido
functions, as is evident from the approximately equal LiϪN
distances [overall variation: Li(1)ϪN(1)/N(2) 1.963(4)/
1.973; Li(2)ϪN(1)/N(3) 2.000(4)/2.011(4); Li(3)ϪN(2)/N(3)
˚
1.976(4)/1.992(4) A]. The lithium atoms are not located
within the planes defined by the two amido-N atoms they
bridge and the oxygen atom of the solvating ether function
but are rather displaced outside the cage structure. Due to
the Li coordination, the aryl rings of the anisyl groups ad-
opt a symmetrical propeller arrangement.
Synthesis and Structures of the Lithium
Triamidostannate(II) HC{SiMe2N(2-MeOC6H4)}3SnLi (3)
and the Rh؊Sn Heterodimetallic Complex HC{SiMe2N(2-
MeOC6H4)}3Sn(Li)؊Rh(η4-C8H12)(Cl) (4)
Figure 4. View of the molecular structure of 3; principal bond
The trilithium triamide 2 was converted into the triami-
dostannate [HC{SiMe2N(2-MeOC6H4)}3SnLi] (3) by treat-
ment of 2 with one molar equivalent of SnCl2 in toluene at
elevated temperature in an ultrasound bath. The reaction
product crystallised as a colourless solid and was isolated
in 63% yield (Scheme 2).
˚
lengths (A) and angles (°): Sn(1)ϪN(1) 2.255(2), Sn(1)ϪN(2)
2.2235(19),
Sn(1)ϪN(3)
2.096(2),
Sn(1)ϪLi(1)
2.931(4),
Li(1)ϪN(2) 2.039(5), Li(1)ϪN(3) 2.139(5), Li(1)ϪO(2) 1.908(5),
Li(1)ϪO(3)
N(1)ϪSn(1)ϪN(3)
N(3)ϪLi(1)ϪN(2)
2.044(5);
N(1)ϪSn(1)ϪN(2)
N(2)ϪSn(1)ϪN(3)
N(2)ϪLi(1)ϪO(2)
94.20(7),
77.84(7),
88.2(2),
96.55(7),
81.03(17),
N(3)ϪLi(1)ϪO(3) 85.39(18)
The lithium stannate 3 crystallises in the centrosym-
metrical space group P21/n, and possesses a molecular
structure in the solid which, albeit distorted, is consistent
with the Cs-symmetry derived from the NMR spectroscopic
data recorded in solution. The most characteristic struc-
tural feature of 3 is undoubtedly the intramolecular coor-
dination of the lithium cation by the peripheral ortho-me-
thoxy groups. The LiϪO bond lengths found in 3 [1.908(5)
Scheme 2
˚
˚
A and 2.044(5) A] are similar to those found in structurally
related solvated metallates, such as HC{SiMe2N[(S)-CH-
1
[13b]
The observation of three H and 13C NMR resonances (Me)Ph]}3SnLi(THF) [1.95(1) A]
and MeSi{SiMe2N-
˚
for the SiMe2 groups (1H: δ ϭ 0.14, 0.59, 0.62 ppm; 13C: (tBu)}3Pb-Li(THF) [2.11(7) A].[5b] Significantly, the lithium
δ ϭ 4.9, 5.6, 6.6 ppm) and two NMR resonances for the cation is placed above the plane, which is spanned by the
MeO groups (1H: δ ϭ 3.04, 3.34 ppm; 13C: δ ϭ 55.0, 55.6 atoms O2, N2, N3 and O3. This exposed position of the
ppm) as well as the detection of two 29Si NMR signals for lithium leads to a very close contact with the adjacent
˚
˚
the SiMe2 groups (δ ϭ Ϫ1.9, Ϫ1.2 ppm) indicate a reduc- methyl group C300 [d(Li1ϪC300) ϭ 2.603(2) A] which ef-
tion of the effective symmetry in solution from C3 to CS. fectively occupies the vacant coordination site of the li-
These spectral patterns are consistent with the coordination thium centre. Such ‘‘agostic’’ interactions with hydrocarbon
of the lithium cation to two amido N-atoms and its internal fragments are quite common in lithium amides provided
‘‘solvation’’ by two of the ortho-anisyl groups. In order to that the coordination numbers of the lithium centres are
establish the details of the molecular structure of this new low.[12] It is therefore surprising to observe this structural
type of lithium stannate(II), an X-ray diffraction study was feature for four-coordinate lithium, which is probably due
carried out (Figure 4).
to the unusual coordination geometry (distorted square
1970
Eur. J. Inorg. Chem. 2002, 1968Ϫ1974

Lithium Cation Solvation in the “Active Ligand Periphery” of a Tripodal Triaminostannate
FULL PAPER
planar instead of tetrahedral) imposed by the rigid caged
structure of the triamidostannate(II).
It is noteworthy that compound 3 is also formed in an in
situ reaction of [HC{SiMe2NH(2-MeOC6H4)}3] (1) with n-
butyllithium and SnCl2 in diethyl ether, and therefore no
indication for a competitive coordination of the anisyl
groups vs. diethyl ether has been found. However, the
formation of 3 using diethyl ether as a reaction medium is
accompanied by a redox process (formation of the free li-
gand) and is therefore unsuitable for a high yield synthetic
protocol.
Due to the efficient intramolecular cation solvation, the
lithium stannate 3 can be viewed as a neutral compound.
In reactions of 3 with transition metal complexes it was
therefore expected to act as a neutral ‘‘ligand’’ and thus
display a behaviour that differs from the anionic stannates
we studied recently.[5,13] Reaction of compound 3 with 0.5
molar equivalents of the dinuclear compound
[Rh(COD)Cl]2 in toluene afforded the mixed heterodimetal-
lic complex [HC{SiMe2N(2-MeOC6H4)}3Sn(Li)ϪRh(η4-
C8H12)(Cl)] (4) in high yield (Scheme 3).
Figure 5. View of the molecular structure of 4; principal bond
˚
lengths (A) and angles (°): Sn(1)ϪN(1) 2.108(2), Sn(1)ϪN(2)
2.137(19),
Sn(1)ϪN(3)
2.164(2),
Sn(1)ϪLi(1)
2.891(5),
Sn(1)ϪRh(1) 2.6048(3), Rh(1)ϪC(43) 2.163(4), Rh(1)ϪC(44)
2.169(4), Rh(1)ϪC(40) 2.114(3), Rh(1)ϪC(47) 2.106(3),
Li(1)ϪN(2) 2.371(6), Li(1)ϪN(3) 2.167(6), Li(1)ϪO(2) 1.976(5),
Li(1)ϪO(3) 2.115(6), Li(1)ϪCl(1) 2.426(5), Rh(1)ϪCl(1) 2.3721(7);
N(1)ϪSn(1)ϪN(2)
N(2)ϪSn(1)ϪN(3)
N(2)ϪLi(1)ϪO(2)
99.80(9),
83.35(8),
76.76(19),
N(1)ϪSn(1)ϪN(3)
N(3)ϪLi(1)ϪN(2)
N(3)ϪLi(1)ϪO(3)
98.77(9),
77.96(18),
77.97(19),
Cl(1)ϪRh(1)ϪSn(1) 83.017(19), Cl(1)ϪLi(1)ϪSn(1) 76.26(14),
Rh(1)ϪSn(1)ϪLi(1) 89.04(11), Rh(1)ϪCl(1)ϪLi(1) 107.07(12)
˚
2.6048(4) A is within the range of previously characterised
RhϪSn complexes.[14] The chloro ligand is additionally
Scheme 3
bonded to the lithium cation of the stannate unit. Although
˚
˚
The observation of a doublet resonance at high field in
the 119Sn NMR spectrum (δ ϭ Ϫ196.3; 1JSnRh ϭ 871.6 Hz)
confirms the formation of a SnϪRh bond and the ele-
mental analysis the formulation given above. The resonance
patterns attributable to the stannate fragment in the 1H,
13C, and 29Si NMR spectra are very similar to those of 3
indicating the retention of the local CS symmetry. This is
consistent with the anticipated nature of the tin cage as a
formally neutral ligand at the rhodium, which retains its
square planar coordination geometry due to the presence
of the chloro ligand and the chelating COD ligand. In order
to obtain a detailed insight into the relative arrangement
of the two metal complex fragments a single crystal X-ray
structure analysis of complex 4 was carried out. Its molecu-
lar structure is depicted in Figure 5 along with the principal
bond lengths and angles.
the Li(1)ϪCl(1) distance of 2.426(5) A is ca. 0.2 A greater
than the LiϪCl bond length found in [HC{SiMe2N(Li)[(S)-
3,3-dimethyl-2-butyl]}3-LiCl(Et2O)3][11a] it is similar to
those previously characterised in a series of LiϪCl com-
plexes.[15]
The lithium stannate ligand has a stronger trans influence
than the chloro ligand as is evident from the metal-carbon
distances to the COD ligand [Rh(1)ϪC(43) 2.163(4), Rh(1)-
˚
2.169(4) A trans to Sn(1) in comparison to Rh(1)ϪC(40)
2.114(3), Rh(1)ϪC(47) 2.106(3) cis to Sn(1)]. As a neutral
ligating unit it therefore resembles the ubiquitous group 15
donor ligands.[16] The trans influence of the lithium stan-
nate ligand in 4 is similar to that previously found in
square-planar [Rh(η4-C8H12)(κ2-P,Sb-iPr2PCH2SbtBu2)]-
PF6.[16a]
As can be seen in Figure 5, the overall structure of the
stannate fragment in the heterodimetallic complex is the
same as in the noncoordinated compound 3. A structural
effect of the transition metal coordination of the tin in 4 is
Conclusion
We have shown in this first study of the tin(II) chemistry
the slight contraction of the SnϪN bonds relative to those of a new tripodal amido ligand containing an ‘‘active ligand
˚
in 3 [average SnϪN distance in 4 is 2.136(2) A compared periphery’’ that the type of lithium-stannate interaction
˚
to 2.192(2) A in 3] which we observed in all the structurally may be controlled by secondary coordinating functions in
characterised transition metal-stannate complexes. The Rh the ligand. The stannates thus obtained can be viewed as
centre in 4 adopts a slightly distorted, square-planar coor- neutral species that may serve as neutral Sn-donor ‘‘li-
dination mode and the tin-rhodium bond length of gands’’ in transition metal chemistry. The scope of this ap-
Eur. J. Inorg. Chem. 2002, 1968Ϫ1974
1971

M. Lutz, C. Galka, M. Haukka, T. A. Pakkanen, L. H. Gade
FULL PAPER
reaction mixture was filtered through a G3 frit, washed with pent-
ane (3 ϫ 10 mL) and dried under vacuum to yield 4.00 g (94%) of a
colourless, microcrystalline powder. 1H NMR (250.13 MHz, C6D6,
295 K): δ ϭ Ϫ0.59 [s, 1 H, HC(SiMe2)3], 0.61 [s, 18 H, Si(CH3)2],
proach, in particular the application of monodentate li-
gands with extremely large cone angles in transition metal
complexes, is currently being studied in our laboratories.
3
4
3.00 (s, 9 H, OCH3), 6.44 (dd, JH,H ϭ 7.8, JH,H ϭ 1.3 Hz, 3 H),
3
4
3
6.58 (dt, JH,H ϭ 7.8, JH,H ϭ 1.3 Hz, 3 H), 6.94 (dt, JH,H ϭ 7.8,
Experimental Section
4JH,H ϭ 1.3 Hz, 3 H), 7.07 (dd, JH,H ϭ 7.8, JH,H ϭ 1.3 Hz, 3 H)
ppm. 7Li{1H} NMR (97.21 MHz, C6D6, 295 K): δ ϭ Ϫ0.4 ppm.
13C{1H} NMR (62.89 MHz, C6D6, 295 K): δ ϭ 6.2 [Si(CH3)2], 12.4
[HC(SiMe2)3], 54.5 (OCH3), 109.1, 113.7, 123.2, 123.4, 149.6, 152.8
(aryl carbons) ppm. 29Si{1H} NMR (49.69 MHz, C6D6, 295 K):
δ ϭ Ϫ1.9 [Si(CH3)2] ppm. C28H40Li3N3O3Si3 (571.72): calcd. C
58.82, H 7.05, N 7.35; found C 58.65, H 6.93, N 7.42.
3
4
All manipulations were performed under nitrogen (desiccant P4O10,
Granusic, J.T. Baker) on a high vacuum line using standard
Schlenk techniques, or in a glovebox. All reaction flasks were
heated prior to use during three evacuation-refill cycles. Solvents
and solutions were transferred by needle-septa techniques. Solvents
were dried according to standard methods and saturated with ni-
trogen. The deuterated solvents used for the NMR spectroscopic
measurements were degassed by three successive ‘‘freeze-pump-
[HC{SiMe2N(2-MeOC6H4)}3SnLi] (3): Toluene (30 mL) was added
to
a mixture of [HC{SiMe2N(2-MeOC6H4)}3Li3] (2) (1.00 g,
˚
thaw’’ cycles and stored over 4 A molecular sieves. Solids were
1.75 mmol) and SnCl2 (332 mg, 1.75 mmol) at room temperature.
The resulting mixture was sonicated for 6 h at 60 °C and sub-
sequently filtered through Celite. The residue was extracted with
hot toluene (2 ϫ 10 mL) and the solvent of the filtrate was evapor-
ated under vacuum. The obtained off white residue was washed
with diethyl ether (10 mL) and pentane (2 ϫ 10 mL) and dried
under vacuum to give 746 mg (63%) of a colourless, microcrystal-
separated from suspensions by filtration through dried Celite. The
1H, 7Li, 13C, 19F, 29Si and 119Sn NMR spectra were recorded on
Bruker AC 200, Bruker Avance 250 and Bruker AMX 400 FT
NMR spectrometers. 1H and 13C data are listed in parts per million
[ppm] relative to tetramethylsilane and are referenced using the re-
sidual protonated solvent peak (1H) or the carbon resonance (13C).
7Li data are listed in ppm relative to LiCl/D2O (1 , external). 29Si
data are listed in ppm relative to tetramethylsilane as an external
standard. 119Sn data are listed in ppm relative to tetramethyltin as
an external standard. Infrared spectra were recorded on a Nicolet
Magna IRTM 750 spectrometer. Elemental analyses were carried
out with a Leco CHNS-932 microanalyzer and a CE-instruments
EA 1110 CHNS-O microanalyzer, respectively. [Rh(COD)Cl]2,[17]
and [HC(SiMe2Br)3][8] were prepared according to published pro-
cedures. o-Methoxyaniline employed in the ligand synthesis was
distilled prior to use. All other chemicals used as starting materials
were obtained commercially and used without further purification.
1
line powder. H NMR (400.13 MHz, C6D6, 295 K): δ ϭ Ϫ0.49 [s,
1 H, HC(SiMe2)3], 0.14, 0.59, 0.62 [s, 18 H, Si(CH3)2], 3.04, 3.34
3
4
(s, 9 H, OCH3), 6.52 (dd, JH,H ϭ 7.9, JH,H ϭ 1.2 Hz, 2 H), 6.67
3
4
3
(dd, JH,H ϭ 9.7, JH,H ϭ 1.5 Hz, 1 H), 6.82 (dt, JH,H ϭ 7.9,
4JH,H ϭ 1.8 Hz, 2 H), 6.85 (dt, JH,H ϭ 7.9, JH,H ϭ 1.4 Hz, 1 H),
3
4
3
4
3
6.93 (dt, JH,H ϭ 7.6, JH,H ϭ 1.5 Hz, 2 H), 7.01 (dt, JH,H ϭ 7.3,
4JH,H ϭ 1.5 Hz, 1 H), 7.34 (dd, 3JH,H ϭ 7.6, 4JH,H ϭ 1.8 Hz, 2 H),
7.42 (dd, JH,H ϭ 7.6, JH,H ϭ 1.5 Hz, 1 H) ppm. Li{1H} NMR
(77.77 MHz, C6D6, 295 K): δ ϭ Ϫ0.3 ppm. 13C{1H} NMR
(100.61 MHz, C6D6, 295 K): δ ϭ 4.9, 5.6, 6.6 [Si(CH3)2], 8.2
[HC(SiMe2)3], 55.0, 55.6 (OCH3), 111.0, 111.6, 120.0, 121.2, 121.6,
123.4, 130.3, 142.5, 143.0, 154.7, 155.1 (aryl carbons) ppm.
29Si{1H} NMR (39.76 MHz, C6D6, 295 K): δ ϭ Ϫ1.9, Ϫ1.2
[Si(CH3)2] ppm. 119Sn{1H} NMR (93.28 MHz, C6D6, 291 K): δ ϭ
Ϫ96.5 ppm. C28H40LiN3O3Si3Sn (676.53): calcd. C 49.71, H 5.96,
N 6.21; found C 49.84, H 5.90, N 5.94.
3
4
7
Preparation of Compounds. [HC{SiMe2NH(2-MeOC6H4)}3] (1): At
0 °C a solution of [HC(SiMe2Br)3] (5.22 g, 12.2 mmol) in diethyl
ether (20 mL) was added dropwise to a vigorously stirred solution
of 2-methoxyaniline (4.51 g, 36.7 mmol) and triethylamine (3.71 g,
36.7 mmol) in diethyl ether (50 mL). After the addition was com-
pleted the reaction mixture was stirred for another 12 h at room
temperature. The solution was filtered through Celite and the res-
idue was extracted with diethyl ether (3 ϫ 20 mL). The solvent was
removed in vacuo and the pale yellow crude product was recrystal-
lized from diethyl ether (10 mL) at Ϫ35 °C to yield 5.61 g (83%) of
a colourless powder. 1H NMR (200.13 MHz, C6D6, 295 K): δ ϭ
0.43 [s, 18 H, Si(CH3)2], 0.93 [s, 1 H, HC(SiMe2)3], 3.27 (s, 9 H,
OCH3), 4.60 (s, 3 H, NH), 6.54Ϫ6.87 (m, 12 H, aryl hydrogens)
[HC{SiMe2N(2-MeOC6H4)}3Sn(Li)؊Rh(η4-C8H12)(Cl)] (4): Tolu-
ene (10 mL) was added to a solid mixture of [HC{SiMe2N(2-
MeOC6H4)}3SnLi] (3) (380 mg, 0.56 mmol) and [Rh(COD)Cl]2
(139 mg, 0.28 mmol) at room temperature. The orange solution was
stirred for a further 12 h at room temperature and subsequently
filtered through Celite. The residue was extracted with toluene
(10 mL) and the filtrate was dried under vacuum. The obtained
yellow residue was washed with pentane (10 mL) and diethyl ether
(5 mL) and dried under vacuum to yield 410 mg (79%) of a yellow,
microcrystalline powder. 1H NMR (250.13 MHz, C6D6, 323 K):
δ ϭ Ϫ0.51 [s, 1 H, HC(SiMe2)3], 0.30, 0.40, 0.45 [s, 18 H, Si(CH3)2],
1.09Ϫ1.86 (m, 8 H, allylic hydrogens), 3.51 (s, 6 H, OCH3), 3.78 (s,
3 H, OCH3), 3.98 (d, 3JH,H ϭ 2.8 Hz, 2 H, olefinic hydrogens), 4.33
ppm. 13C{1H} NMR (50.32 MHz, C6D6, 295 K):
δ ϭ 2.9
[Si(CH3)2], 4.6 [HC(SiMe2)3], 55.1 (OCH3), 110.6, 115.2, 117.7,
121.8, 137.4, 148.6 (aryl carbons) ppm. 29Si{1H} NMR
(39.76 MHz, C6D6, 295 K): δ ϭ 1.6 [Si(CH3)2] ppm. IR (KBr): ν˜ ϭ
3373 cmϪ1 vs, 3060 w, 2958 m, 2894 w, 2843 w, 2830 w, 1602 vs,
1519 vs, 1909 ww, 1858 ww, 1449 m, 1398 s, 1329 m, 1301 m, 1261
w, 1244 w, 1219 w, 1179 m, 1111 s, 1054 w, 1037 m, 1000 s, 900 vs,
846 vs, 767 w, 744 m, 738 m, 687 vw. C28H43N3O3Si3 (553.92):
calcd. C 60.71, H 7.82, N 7.59; found C 60.55, H 7.93, N 7.56.
3
(d, JH,H ϭ 2.5 Hz, 2 H, olefinic hydrogens), 6.61Ϫ7.41 (m, 12 H,
aryl hydrogens) ppm. 7Li{1H} NMR (97.21 MHz, C6D6, 295 K):
δ ϭ 1.5 ppm. 13C{1H} NMR (62.89 MHz, C6D6, 323 K): δ ϭ 5.0
[Si(CH3)2], 5.6 [br, Si(CH3)2], 8.1 [HC(SiMe2)3], 28.0, 33.7 (allylic
[HC{SiMe2N(Li)(2-MeOC6H4)}3] (2): n-Butyllithium (14 mL, carbons), 55.0, 55.2 (OCH3), 63.8 (d, 1JRhC ϭ 13.3 Hz, olefinic car-
1
22.4 mmol of a 1.6 mol/L solution in hexane) was added to a slurry
of [HC{SiMe2NH(2-MeOC6H4)}3] (1) (4.13 g, 7.45 mmol) in pent-
ane (50 mL) at Ϫ20 °C. The reaction mixture was slowly warmed
up to ambient temperature and stirring at room temperature was
continued for 2 h. The off white slurry was subsequently refluxed
for 15 min and stirred for a further 12 h at room temperature. The
bons), 94.5 (d, JRhC ϭ 8.3 Hz, olefinic carbons), 110.7, 110.9,
121.3, 121.8, 122.2, 122.8, 128.1, 130.9, 141.6, 141.8, 155.6, 155.9
(aryl carbons) ppm. 29Si{1H} NMR (49.69 MHz, C6D6, 295 K):
δ ϭ 1.4, 2.0 [Si(CH3)2] ppm. 119Sn{1H} NMR (149.19 MHz, C6D6,
1
291 K): δ ϭ Ϫ196.3 (d, JRhSn ϭ 871.6 Hz, N3Sn؊Rh) ppm. IR
(KBr): ν˜ ϭ 3379 cmϪ1 s, 3068 vw, 2961m, 2834 vw, 2289 vw, 2019
1972
Eur. J. Inorg. Chem. 2002, 1968Ϫ1974

Lithium Cation Solvation in the “Active Ligand Periphery” of a Tripodal Triaminostannate
Table 1. Crystal data and structure refinement for 1, 2, 3 and 4
FULL PAPER
1
2
3
4
Molecular formula
Mr
C28H43N3O3Si3·C6D6
638.07
C28H40Li3N3O3Si3Sn·2.5C6D6
782.08
C28H40LiN3O3Si3Sn
676.53
C36H49ClLiN3O3RhSi3Sn·C6D6
1004.19
Temperature
Wavelength
Crystal system
Space group
Z
150(2) K
0.71073 A
Monoclinic
P21/c
150(2) K
0.71073 A
Monoclinic
C2/c
173(2) K
0.71073 A
Monoclinic
P21/c
150(2) K
0.71073 A
Monoclinic
P21/c
˚
˚
˚
˚
4
8
4
4
˚
˚
˚
˚
˚
˚
Unit cell dimensions
a ϭ 14.03350(10) A
b ϭ 15.1319(2) A
c ϭ 17.0806(2) A
a ϭ 24.5027(3) A
b ϭ 15.8137(3) A
c ϭ 24.7797(4) A
a ϭ 9.1341(18) A
b ϭ 14.172(3) A
c ϭ 24.977(5) A
a ϭ 12.13230(10) A
b ϭ 19.5031(2) A
c ϭ 18.7930(2) A
˚
˚
˚
˚
˚
˚
α ϭ 90°
β ϭ 99.5400(6)°
γ ϭ 90°
3576.96(7) A
1.185 g cmϪ1
0.169 mmϪ1
1360
α ϭ 90°
β ϭ 116.6346(6)°
γ ϭ 90°
8582.7(2) A
1.211 g cmϪ1
0.151 mmϪ1
3272
α ϭ 90°
β ϭ 94.57(3)°
γ ϭ 90°
3222.9(11) A
1.394 g cmϪ1
0.936 mmϪ1
1392
α ϭ 90°
β ϭ 92.2699(4)°
γ ϭ 90°
4443.26(8) A
1.501 g cmϪ1
1.115 mmϪ1
2036
3
3
3
3
˚
˚
˚
˚
Volume
Dcalcd.
Absorption coefficient
F(000)
Crytal size [mm]
θ range for data collection
Limiting indices
0.30 ϫ 0.30 ϫ 0.30
3.92 to 27.45°
Ϫ18 Յ h Յ 18
Ϫ19 Յ k Յ 19
Ϫ22 Յ l Յ 22
15821
0.30 ϫ 0.30 ϫ 0.10
2.58 to 27.48°
Ϫ31 Յ h Յ 31
Ϫ20 Յ k Յ 20
Ϫ32 Յ l Յ 32
18820
0.35 ϫ 0.25 ϫ 0.15
2.32 to 25.0°
Ϫ10 Յ h Յ 10
Ϫ16 Յ k Յ 16
Ϫ29 Յ l Յ 29
30955
0.30 ϫ 0.30 ϫ 0.30
3.41 to 26.37°
Ϫ15 Յ h Յ 15
Ϫ24 Յ k Յ 24
Ϫ23 Յ l Յ 23
53620
Reflections collected
Independent reflections (Rint.
Refinement method
)
8128 (0.0231)
Full-matrix least-squares
on F2
9714 (0.0390)
Full-matrix least-squares
on F2
5666 (0.0401)
Full-matrix least-squares
on F2
9064 (0.0479)
Full-matrix least-squares
on F2
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices
[I Ͼ 2σ(I)]
R indices (all data)
8128/0/397
1.043
R1 ϭ 0.0429
wR2 ϭ 0.1086
R1 ϭ 0.0604
wR2 ϭ 0.1212
9714/0/505
1.022
R1 ϭ 0.0484
wR2 ϭ 0.1060
R1 ϭ 0.0853
wR2 ϭ 0.1209
5666/0/361
1.030
R1 ϭ 0.0268
wR2 ϭ 0.0679
R1 ϭ 0.0335
wR2 ϭ 0.0698
9064/0/524
1.082
R1 ϭ 0.0298
wR2 ϭ 0.0676
R1 ϭ 0.0410
wR2 ϭ 0.0725
Ϫ3
Ϫ3
Ϫ3
Ϫ3
˚
˚
˚
˚
Largest diff. peak and hole
0.298 and Ϫ0.290 e·A
0.249 and Ϫ0.290 e·A
0.659 and Ϫ0.498 e·A
0.676 and Ϫ0.647 e·A
vw, 1602 s, 1515 vs, 1444 m, 1393 m, 1332 s, 1301 s, 1240 vs, 1179 CCDC-178729 (1), -178730 (2), -178731 (3) and -178732 (4) contain
w, 1113 s, 1052 w, 1042 m, 1006 m, 904 s, 843 s, 772 w, 746 m, 690 the supplementary crystallographic data for this paper. These data
vw. C36H52ClLiN3O3RhSi3Sn (923.07): calcd. C 46.84, H 5.68, N
4.55; found C 47.13, H 5.80, N 4.24.
can be obtained free of charge at www.ccdc.cam.ac.uk/conts/
retrieving.html [or from the Cambridge Crystallographic
Data
Centre,
12,
Union
Road,
Cambridge
CB2 1EZ, UK; Fax: (internat.) ϩ44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
X-ray Crystallographic Study of Compounds 1؊4
The X-ray diffraction data were collected on a Nonius KappaCCD
diffractometer (1, 2, and 4) or on an IPDS (STOE) diffractometer Acknowledgments
˚
(3) using Mo-Kα radiation (λ
ϭ
0.71073 A). The Denzo-
We thank the European Union (TMR program, network
MECATSYN), the CNRS (France) the Deutsche Forschungsgeme-
inschaft (SFB 347), and the Institut Universitaire de France for
financial support.
Scalepack[18] program package or IPDS programs were used for
cell refinements and data reduction. A multi-scan absorption cor-
rection, based on equivalent reflections (XPREP in SHELXTL
v5.1),[19] was applied to the data of 4 (Tmax/Tmin 0.26648/0.21770).
Structures were solved by direct methods using the SHELXS-97[20]
(1, 3 and 4) or SIR-97[21] (2) program. All structures were refined
with the SHELXL-97[22] program. In 3 hydrogens were located
from a difference Fourier map and refined isotropically. In 1, 2 and
4 hydrogens were placed on an idealized position and constrained
to ride on their parent atom. The crystallographic data are
summarised in Table 1. The molecular structures of the complexes
along with principal bond lengths and angles are presented in
Figure 2Ϫ5.
[1]
Selected examples: [1a] M. Veith, R. Rösler, Z. Naturforsch., Teil
[1b]
B 1986, 41, 1071Ϫ1080.
M. Veith, D. Käfer, V. Huch, An-
gew. Chem. 1986, 98, 367Ϫ368; Angew. Chem. Int. Ed. Engl.
1986, 25, 375Ϫ377. [1c] M. Veith, C. Ruloff, V. Huch, F. Töllner,
Angew. Chem. 1988, 100, 1418Ϫ1419; Angew. Chem. Int. Ed.
[1d]
Engl. 1988, 27, 1381Ϫ1382.
M. A. Beswick, M. K. Davies,
P. R. Raithby, A. Steiner, D. S. Wright, Organometallics 1997,
[1e]
16, 1109Ϫ1110.
A. Steiner, D. Stalke, J. Chem. Soc., Chem.
[1f]
Commun. 1993, 1702Ϫ1704.
H. V. R. Dais, M. M.
Eur. J. Inorg. Chem. 2002, 1968Ϫ1974
1973

M. Lutz, C. Galka, M. Haukka, T. A. Pakkanen, L. H. Gade
FULL PAPER
[13f]
Olmstead, K. Ruhlandt-Senge, P. P. Power, J. Organomet.
Scowen, M. McPartlin, Inorg. Chem. 1997, 36, 960Ϫ961.
[1g]
Chem. 1993, 462, 1Ϫ6.
D. Reed, D. Stalke, D. S. Wright,
M. Lutz, B. Findeis, M. Haukka, T. A. Pakkanen, L. H. Gade,
Organometallics 2001, 20, 2505Ϫ2509. [13g] M. Lutz, B. Findeis,
M. Haukka, T. A. Pakkanen, L. H. Gade, Eur. J. Inorg. Chem.
2001, 3155Ϫ3162.
[14]
Angew. Chem. 1991, 103, 1539Ϫ1540; Angew. Chem. Int. Ed.
Engl. 1991, 30, 1459Ϫ1460. [1h] D. R. Armstrong, M. G. David-
son, D. Moncrieff, D. Stalke, D. S. Wright, J. Chem. Soc.,
Chem. Commun. 1992, 1413Ϫ1414.
Lappert, G. A. Lawless, B. Royo, J. Chem. Soc., Chem. Com-
[1i]
P. B. Hitchcock, M. F.
Examples of recently structurally characterised RhϪSn bonds:
[14a]
H. Werner, O. Gevert, P. Haquette, Organometallics 1997,
[1j]
[14b]
mun. 1993, 554Ϫ555.
M. A. Paver, C. A. Russel, D. S.
16, 803Ϫ806.
M. A. Garralda, E. Pinilla, M. A. Monge,
[14c]
Wright, Angew. Chem. 1995, 107, 1677Ϫ1686; Angew. Chem.
J. Organomet. Chem. 1992, 427, 193Ϫ200.
L. Carlton, R.
Int. Ed. Engl. 1995, 34, 1545Ϫ1554.
Weber, D. C. Levendis, Inorg. Chem. 1998, 37, 1264Ϫ1271. [14d]
[2] [2a]
[2b]
M. Veith, Chem. Rev. 1990, 90, 3Ϫ16.
M. Veith, Adv.
M. Veith, Angew.
D. Kruber, K. Merzweiler, C. Wagner, H. Weichmann, J. Or-
[2c]
[14e]
Organomet. Chem. 1990, 31, 269Ϫ300.
Chem. Int. Ed. Engl. 1987, 26, 1Ϫ14.
M. F. Lappert, P. P. Power, A. R. Sanger, R. C. Srivastava,
Metal and Metalloid Amides; Ellis Horwood, Chichester, U. K.,
1980. Ϫ
ganomet. Chem. 1999, 572, 117Ϫ123.
S. Licoccia, R. Pao-
lesse, T. Boschi, Acta Crystallogr., Sect. C 1995, 51, 833Ϫ835.
[3]
[15] [15a]
W. J. Evans, J. L Shreeve, R. N. R. Broomhall-Dillard, J.
[15b]
W. Ziller, J. Organomet. Chem. 1995, 501, 7Ϫ11.
U. Pia-
rulli, A. J. Rogers, C. Floriani, G. Bervasio, D. Viterbo, Inorg.
Chem. 1997, 36, 6127Ϫ6133. [15c] G. B. Deacon, C. M. Forsyth,
P. C. Junk, B. W. Skelton, A. H. White, J. Chem. Soc., Dalton
[4]
[5]
Review: L. H. Gade, Eur. J. Inorg. Chem. 2002, 1257Ϫ1268.
[5a] K. W. Hellmann, P. Steinert, L. H. Gade, Inorg. Chem. 1994,
[5b]
33, 3859Ϫ3960.
K. W. Hellmann, L. H. Gade, O. Gevert,
Trans. 1998, 1381Ϫ1388. For recent examples of µ3-capping
[15d]
P. Steinert, J. W. Lauher, Inorg. Chem. 1995, 34, 4069Ϫ4078.
H. Memmler, K. Walsh, L. H. Gade, J. W. Lauher, Inorg. Chem.
1995, 34, 4062Ϫ4068.
halides on Li3 faces see, for example:
R. Fleischer, D.
[6]
[15e]
Stalke, Coord. Chem. Rev. 1998, 176, 431Ϫ450.
ischer, D. Stalke, J. Chem. Soc., Dalton Trans. 1998, 193Ϫ197.
[16] [16a]
R. Fle-
[7]
[8]
L. H. Gade, Chem. Commun. 2000, 173Ϫ182.
M. Manger, J. Wolf, M. Laubender, M. Treichert, D.
[16b]
[8a] L. H. Gade, C. Becker, J. W. Lauher, Inorg. Chem. 1993, 32,
Stalke, H. Werner, Chem. Eur. J. 1997, 3, 1442Ϫ1450.
M.
[8b]
2308Ϫ2314.
C. Eaborn, P. B. Hitchcock, P. D. Lickiss, J.
Manger, O. Gevert, H. Werner, Chem. Ber./Recueil 1997, 130,
[16c]
Organomet. Chem. 1983, 252, 281Ϫ288.
H. Memmler, L. H. Gade, J. W. Lauher, Inorg. Chem. 1994,
33, 3064Ϫ3071.
1529Ϫ1531.
H. Werner, A. Heinemann, B. Windmüller, P.
[9]
[16d]
Steinert, Chem. Ber. 1996, 129, 903Ϫ910.
P. Schwab, N.
Mahr, J. Wolf, H. Werner, Angew. Chem. Int. Ed. Engl. 1993,
[10] [10a]
L. H. Gade, N. Mahr, J. Chem. Soc., Dalton Trans. 1993,
32, 1480Ϫ1482.
[10b]
[17]
[18]
489Ϫ494.
M. Schubart, B. Findeis, L. H. Gade, W.-S. Li,
G. Giordano, R. H. Crabtree, Inorg. Synth. 1990, 28, 88Ϫ90.
Z. Otwinowski, W. Minor, Processing of X-ray Diffraction Data
Collected in Oscillation Mode, in Methods in Enzymology, Vol-
ume 276, Macromolecular Crystallography, part A, (Eds.: C. W.
Carter, Jr. and R. M. Sweet), Academic Press, New York, 1997,
p. 307Ϫ326.
G. M. Sheldrick, SHELXTL Version 5.1, Bruker Analytical X-
ray Systems, Bruker AXS, Inc. Madison, Wisconsin, USA,
1998.
G. M. Sheldrick, SHELS-97, Program for Crystal Structure
Determination, University of Göttingen, 1997.
A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C.
Giacovazzo, A. Guagliardi, A. G. Moliterni, G. Polidori, R. J.
Spagna, Appl. Cryst. 1999, 32, 115Ϫ119.
G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
Received February 6, 2002
M. McPartlin, Chem. Ber. 1995, 128, 329Ϫ334.
[11] [11a]
P. Renner, C. H. Galka, L. H. Gade, S. Radojevic, M.
[11b]
McPartlin, Eur. J. Inorg. Chem. 2001, 1425Ϫ1430.
L. H.
Gade, P. Renner, H. Memmler, F. Fecher, C. H. Galka, M.
Laubender, S. Radojevic, M. McPartlin, J. W. Lauher, Chem.
Eur. J. 2001, 7, 2563Ϫ2580.
[19]
[12]
K. Gregory, P. v. R. Schleyer, R. Snaith, Adv. Inorg. Chem.
1991, 37, 47Ϫ142 and references cited therein. See also: R. E.
Mulvey, Chem. Soc. Rev. 1999, 27, 339Ϫ346.
[20]
[21]
[13] [13a]
K. W. Hellmann, S. Friedrich, L. H. Gade, W.-S. Li, M.
McPartlin, Chem. Ber. 1995, 128, 29Ϫ34. [13b] H. Memmler, U.
Kauper, L. H. Gade, D. Stalke, J. W. Lauher, Organometallics
[13c]
1996, 15, 3637Ϫ3939.
Gade, I. Scowen, M. McPartlin, M. Laguna, Inorg. Chem.
1996, 35, 3713Ϫ3715.
M. Laguna, M. C. Gimeno, I. J. Scowen, M. McPartlin, Inorg.
M. Contel, K. W. Hellmann, L. H.
[22]
[13d]
B. Findeis, M. Contel, L. H. Gade,
[13e]
Chem. 1997, 36, 2386Ϫ2390.
B. Findeis, L. H. Gade, I. J.
[I02061]
1974
Eur. J. Inorg. Chem. 2002, 1968Ϫ1974