Syntheses and structures of lanthanoid(ii) complexes featuring Sn-M (M = Al, Ga, In) bonds

Article abstract of DOI:10.1039/c2dt31768k

The reactions of the tris(pyridyl)tin(ii) derivative [Li(thf)Sn(2-py ^R)₃] (py^R = C₅H₃N-5-Me) (1) with the heavier group 13 alkyl compounds MEt₃, M = Ga or In, have been carried out. These led to formation of [{Li(thf)Sn(2-py ^R)₃}MEt₃] adducts, which exhibit long Sn-M bonds and can be used for further lanthanoid metal coordination via the salt metathesis reaction with [Eu(Cp*)₂(OEt₂)] (Cp* = η⁵-C₅Me₅) to give complexes [Eu{Sn(2-py^R)₃MEt₃}₂]. In contrast, addition of the lighter group 13 analogue, (AlMe₃)₂, to 1 resulted in a pyridyl transfer reaction, yielding dimeric [AlMe ₂(2-py^R)]₂. For comparison, the reaction of (AlMe₃)₂ with [Yb{Sn(2-py^R)₃} ₂] (py^R = C₅H₃N-3-Me) was explored, affording complex [Yb{Sn(2-py^R)₃AlMe₃} ₂]. All complexes have been characterised by NMR spectroscopy and X-ray crystallographic studies. The Royal Society of Chemistry 2012.

Full text of DOI:10.1039/c2dt31768k

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
Dalton
Transactions
Cite this: Dalton Trans., 2012, 41, 14101
www.rsc.org/dalton
PAPER
Syntheses and structures of lanthanoid(II) complexes featuring Sn–M
M = Al, Ga, In) bonds†
(
Kornelia Zeckert*
Received 2nd August 2012, Accepted 12th September 2012
DOI: 10.1039/c2dt31768k
R
R
The reactions of the tris(pyridyl)tin(II) derivative [Li(thf)Sn(2-py ) ] (py = C H N-5-Me) (1) with
3
5 3
the heavier group 13 alkyl compounds MEt , M = Ga or In, have been carried out. These led to
3
R
formation of [{Li(thf)Sn(2-py ) }MEt ] adducts, which exhibit long Sn–M bonds and can be used for
3
3
further lanthanoid metal coordination via the salt metathesis reaction with [Eu(Cp*) (OEt )] (Cp* =
2
2
5
R
η -C Me ) to give complexes [Eu{Sn(2-py ) MEt } ]. In contrast, addition of the lighter group 13 analogue,
5
5
3
3 2
R
3 2 2 2
(
AlMe ) , to 1 resulted in a pyridyl transfer reaction, yielding dimeric [AlMe (2-py )] . For comparison,
R
R
the reaction of (AlMe ) with [Yb{Sn(2-py ) } ] (py = C H N-3-Me) was explored, affording complex
Yb{Sn(2-py ) AlMe } ]. All complexes have been characterised by NMR spectroscopy and X-ray
3
2
3 2
5 3
R
[
3 3 2
crystallographic studies.
and therefore they are prospective two-electron donors. In the
Introduction
course of our studies, we have investigated the reactivity of the
R
Divalent tin compounds SnR are well known as ligands in
2
zwitter-ionic tris(aryl)tin(II) compound [Li(thf)Sn(2-py ) ]
3
1
,2
R
transition metal chemistry. In their complexes the stannylenes
may function as σ-donors and π-acceptors due to the lone pair of
electrons and the vacant p orbital at the tin atom. Besides
various transition metal stannylene complexes similar main
(
py = C H N-5-Me) (1) towards trivalent organolanthanoid
5
3
compounds, yielding stable Sn–Ln bonded donor–acceptor com-
R
5
plexes [{Li(thf)Sn(2-py ) }Ln(Cp) ] (Ln = La, Yb; Cp = η -
3
3
10
C H ). In contrast, treatment of 1 with corresponding divalent
5
5
group metal complexes are scarce. Few tin(II) complexes [Sn{8-
lanthanoid compounds led to metathesis reactions and yielded
3
R
11
(
(
CHSiMe )C H N} SnCl ],
[Sn{2,6-(NMe ) C H } Sn{1,8-
2 2 6 3 2
3
9
6
2
2
[Ln{Sn(2-py ) } ] (Ln = Eu, Yb). In these complexes the
3 2
t
4
t
NCH Bu) C H } ] and [Sn(R)Sn{1,2-[N( Bu)(SiMe )CC(H)] -
2
2
10 6 2
t
3
2
divalent lanthanoids are solely coordinated by the pyridine rings
t
3
C H }] (R = 1-{N( Bu)C(SiMe )C(H)}-2-{N( Bu)(SiMe )CC(H)}-
C H ) are known, in which each of the tin(II) fragments
6
4
3
3
in a κ N-fashion, whereas the lone pair of electrons at the tin
5
6
4
atom is still available and hence attractive for further donation.
Herein we report on lanthanoid(II) complexes based on tin–group
either acts as a Lewis acid or a base. Further stable tin(II)
donation was only reported to group 13 Lewis acids in [Sn{2,6-
1
3 element adducts, which can be obtained either through sub-
t
R
(
(
[
NMe ) C H } BH ] (I) as well as [{Sn(μ -N Bu)} (AlCl ) ]
II). Recently, Jones presented the ionic complexes [K(tmeda)]-
2
2
6
3 2
3
3
4
3 2
sequent metal coordination starting from [Ln{Sn(2-py ) } ] or
3 2
6
by the salt metathesis reaction of the former novel tin–group
13 element bonded complexes. Hence, reactions of 1 with alkyl
i
2
SnR Ga{[N(Ar)C(H)] }] (R = CH(SiMe ) , C H Pr -2,4,6; Ar =
2
2
3 2
6
3
i
C H Pr -2,6) (III), which can be considered as weakly bound
6
3
2
compounds of the heavier group 13 elements M(Alk) (M =
3
adducts of the anionic gallium(I) heterocycle with the stannylene
Al, Ga, In) have firstly been explored.
7
fragments.
Results and discussion
Lithium tris(2-pyridyl)stannate adducts of the group 13 element
compounds
The reactions of the lithium tris(2-pyridyl)stannate [Li(thf)Sn-
8
R
R
Similar to stannylenes SnR , anionic trialkoxy- or triamido-
(2-py )
3
] (py = C
5
H
3
N-5-Me) (1) with the alkyl derivatives of
(M = Ga, In) were performed in a 1 : 1
2
9
stannates also provide a lone pair of electrons at the tin atom
the group 13 metals MEt
3
stoichiometry in toluene at room temperature (Scheme 1).
During addition of MEt spontaneous reaction of the toluene-
3
Universität Leipzig, Institut für Anorganische Chemie, Johannisallee 29,
D-04103 Leipzig, Germany. E-mail: zeckert@uni-leipzig.de
insoluble compound 1 was observed. Concentration of the final
clear solutions afforded the crystalline Sn–M bonded adducts in
good yields.
†
CCDC 887941–887946. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c2dt31768k
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 14101–14106 | 14101

View Article Online
Scheme 1 Reaction conditions: (i) toluene, RT; (i) + (ii) THF for 3b.
Fig. 2 Thermal ellipsoid plot (30% probability surface) of the molecu-
R
lar structure of [{Li(thf)Sn(2-py )
3
}InEt
3
] (4); hydrogen atoms, thf and
ethyl group disorder have been omitted for clarity. Selected bond lengths
Å) and angles (°): Sn1–In1 2.8638(7), Sn1⋯Li1 3.261(11), Sn1–C1
.199(5), Sn1–C7 2.199(6), Sn1–C13 2.189(7), In1–C19 2.194(10),
(
2
In1–C21 2.166(12), In1–C23 2.114(17), C1–Sn1–C7 98.0(2), C1–Sn1–
C13 97.0(2), C7–Sn1–C13 95.9(2); selected bond lengths (Å) and
R
angles (°) for [{Li(thf)Sn(2-py )
3
}GaEt
3
] (3b): Sn1–Ga1 2.7196(11),
Fig. 1 Thermal ellipsoid plot (30% probability surface) of the solid
Sn1⋯Li1 3.261(13), Sn1–C1 2.193(7), Sn1–C7 2.186(8), Sn1–C13
.199(7), Ga1–C19 1.988(8), Ga1–C21 2.000(6), Ga1–C23 2.022(10),
C1–Sn1–C7 96.0(3), C1–Sn1–C13 97.6(3), C7–Sn1–C13 96.6(3).
R
state structure of [{LiSn(2-py )
3
3
}GaEt ]
n
(3a); only a dimeric unit of
2
the polymeric chain is shown; hydrogen atoms and ethyl group disorder
have been omitted for clarity. Selected bond lengths (Å) and angles (°):
Sn1–Ga1 2.6943(4), Sn1⋯Li1 3.233(6), Sn–C1 2.194(3), Sn1–C7
2
.191(3), Ga1–C13 2.011(4), Ga1–C15 1.997(5), Li1–C13′ 2.429(7),
reaction of 1 with InEt resulted in straight formation of the
3
C1–Sn1–C1 95.0(1), C1–Sn1–C7 98.4(1), C13–Ga–C15 116.2(2), C15–
Ga1–C15 107.1(5).
R
indium monomer analogue [{Li(thf)Sn(2-py ) }InEt ] (4).
3
3
X-ray crystallographic analyses of adducts 3b and 4 were
carried out. Compounds 3b and 4 have similar structures con-
taining two crystallographically independent molecules in the
asymmetric unit, which show no significant geometrical differ-
ences. Therefore only the molecular structure of 4 is depicted in
Fig. 2 with geometric parameters for only one molecule included
in the caption. As in the previously described polymeric gallium
complex 3a, the tin atom possesses a trigonal pyramidal geome-
try with Cipso–Sn–Cipso angles ranging from 95.9(2)° to 98.0(2)°.
Although a more precise interpretation is restricted due to strong
disorder of the ethyl groups at the gallium or indium atom in the
complexes, it appears that the C–M–C angles are considerably
more acute in 3b and 4 than 120° (D3h symmetry) in free metal-
lane. The Sn–M bond lengths (2.7196(11) Å in 3b and 2.8638
(7) Å in 4) lie outside the sum of the respective covalent radii
X-ray crystallographic determination of the gallium complex
R
[
{LiSn(2-py ) }GaEt ] (3a) revealed a polymeric chain struc-
3
3 n
ture in the solid state featuring a Li–C–Ga two-electron three-
centre bond with Li–C and Ga–C distances of 2.429(7) Å
and 2.011(4) Å, respectively (Fig. 1). The Sn–Ga bond length
of 2.6943(4) Å can be compared to Sn–Ga bond lengths
determined for III (2.7186(6) Å) as well as for [K(tmeda)]-
i
[
(
Sn{CH(SiMe ) }[Ga{[N(Ar)C(H)] }] ] (Ar = C H Pr -2,6)
3
7
2
2
2
6
3
2
2.6610(6) Å).
The NMR spectroscopic data suggest that the stannate unit
remains coordinated to the gallane fragment in solution with
room temperature Sn NMR resonances of δ = −208 ppm in
d -THF and δ = −213 ppm in d -toluene. Although these Sn
119
119
8
8
12
NMR resonances are shifted only slightly to higher field in
relation to the signal for the parent lithium stannate 1 (δ =
181 ppm), they are consistent with Sn being four-coordinate.
(Sn–Ga 2.65 Å, Sn–In 2.81 Å) and therefore may be con-
sidered weak. It should be mentioned that there have been no
previously structurally characterized Sn–In bonds in molecular
compounds.
−
No changes in the spectra were detected on cooling. Moreover, a
119
1
low temperature Sn{ H} NMR experiment for a mixture of 1
Contrary to formation of compounds 3b and 4, the synthesis
of an analogous Sn–Al bonded donor–acceptor complex failed.
Instead, 1 reacted with (AlMe ) to give the aluminium dimer
and adduct 3a in d -THF at 193 K revealed two well separated
8
signals for both individual compounds at δ = −181 ppm (1) and
3
2
R
−
208 ppm (3a), respectively, supporting the stability of the Sn–
[AlMe (2-py )] (5) in 74% yield, being the only isolated and
2 2
1
Ga bond in solution. The H NMR spectrum of the gallane
identified product from the red reaction solution so far. Its for-
mation may result from an insertion of the aluminium into one
of the Sn–Cipso bonds of a transient lithium tris(2-pyridyl)stan-
nate alane adduct.
adduct in d -THF turned out to be more symmetrical than one
8
would expect for a polymeric structure in solution, rather indicat-
ing a monomeric complex to be present. Indeed, colourless crys-
R
1
tals of a thf-solvated complex [{Li(thf)Sn(2-py ) }GaEt ] (3b)
The H NMR spectrum of isolated crystals displays one set of
3
3
were isolated from concentrated THF solution. Interestingly, the
resonances according to the formation of only one isomer
14102 | Dalton Trans., 2012, 41, 14101–14106
This journal is © The Royal Society of Chemistry 2012

View Article Online
Scheme 2
Scheme 3
Scheme 4
(
Scheme 2), in which the two aluminium centres are coordinat-
broadened signals between δ = 0.7 and 8.7 ppm for 6 as well as
δ = 0.3 and 8.4 ppm for 7. Since compound 9 is poorly soluble
in non-polar solvents, the NMR spectra were recorded in
ing by the bridging 2-pyridyl ligands in a transoid fashion. This
is in contrast to previously reported H NMR spectroscopic obser-
vations for the archetype compound [AlMe (2-py)]2 (py =
C H N), which was obtained as a mixture of cis and trans isomers
1
2
d -THF, indicating Sn–Al bond dissociation with characteristic
8
5
4
1
H NMR resonance for the methyl groups of free AlMe at δ =
13
3
from a low-temperature reaction of AlMe Cl with 2-Li-py.
119
1
2
−
0.97 ppm. Moreover, in the
Sn{ H} NMR spectrum only
one signal at δ = −235 ppm was detected which can be assigned
to uncoordinated complex 8.
Lanthanoid(II) complexes of Sn–M bonded adducts
The X-ray crystallographic analyses showed that compounds 6
and 7 have similar structures; hence only the molecular structure
of 7 (Fig. 3) is included here. In the complexes 6 and 7 the euro-
pium atoms are octahedrally coordinated by six pyridyl nitrogen
donor atoms with a staggered arrangement of the pyridine rings
around the metal centre. The large size of the lanthanoid atom
We reported earlier that the tris(2-pyridyl)stannate unit com-
plexes divalent lanthanoids via the salt metathesis reaction,
which is, however, so far limited to the cyclopentadienyl deriva-
5
11
tives [Ln(Cp*) (OEt )] (Ln = Eu, Yb; Cp* = η -C Me ). Since
2
2
5
5
the Sn–M bonded adducts 3b and 4 are still attractive for salt
metathesis reactions, we explored their reactivity towards [Eu-
affords a slight twisting of all pyridine rings around the Sn–Cipso
bonds (6, 2.8(2)–7.8(2)°; 7, 0.3(3)–4.3(3)°). The Eu–N distances
(
Cp*) (OEt )] assuming that LiCp* elimination and encapsula-
2 2
2+
and the N–Eu–N angles are similar to those in [Eu{Sn(2-
tion of the Eu cation may occur with the Sn–M bond being
retained. Indeed, treating either a solution of 3b or 4 in toluene
with the europocene derivative in a 2 : 1 stoichiometry immedi-
ately resulted in red solutions with concomitant precipitation of
LiCp*. After filtration and concentration the complexes [Eu{Sn-
(
tals in good yields (Scheme 3).
Furthermore, the suitability of adduct formation for the lantha-
noid(II) bis(stannate) complexes themselves was investigated by
using the ytterbium bis(stannate) complex [Yb{Sn(2-py ) } ]
(
R
11
py ) } ]. The Sn–M distances are somewhat longer than in the
3 2
previously reported adducts, which correlates with the Cipso–Sn–
Cipso angles being more obtuse upon lanthanoid metal
coordination.
R
In the solid state complex 9 shows bonding characteristics
similar to 6 and 7 (Fig. 4), but contrasts with the ytterbium atom
being almost ideal octahedrally coordinated with a strictly linear
Sn⋯Yb⋯Sn axis (180.0°). Consequently, the paddle wheel
arrangement of the pyridine rings is more significantly expressed
by the angle between the Al–Sn⋯Yb vector and the pyridine
2-py ) MEt } ] (M = Ga (6), In (7)) were isolated as red crys-
3
3 2
R
3
2
R
py = C H N-3-Me) (8), obtained by reaction of a second
5 3
R
plane (61.3°). The Sn–Al bond length of 2.8317(10) Å is longer
lithium tris(2-pyridyl)stannate [Li(thf)Sn(2-py ) ] (2) with [Yb-
(
3
t
than in [{Sn(μ -N Bu)} (AlCl ) ] (II) (2.78(1) Å). However, the
Cp*) (OEt )]. Simple addition of (AlMe ) to a solution of
3
4
3 2
2
2
3 2
CMe–Al–CMe angles clearly pass from D3h in free metallane to
Td in the complex, implying covalent Sn–Al bond character,
which parallels results of theoretical investigations for the model
complex 8 at room temperature gave dark brown crystalline [Yb-
R
{
Sn(2-py ) AlMe } ] (9), which slowly crystallised from the
3 3 2
reaction mixture in almost quantitative yield (Scheme 4). The
latter result contrasts the formerly described unsuccessful reac-
tion of the simple lithium stannate (1) with (AlMe ) and is even
−
14
compounds [H AlEH ] (E = C, Si, Ge).
3
3
3
2
more surprising with a more pronounced steric demand of the
pyridyl ligand employed in 8 compared to 1.
Conclusions
NMR studies of complexes 6 and 7 were thwarted by their
In summary, the reactions of a zwitter-ionic tris(aryl)tin(II)
derivative, [Li(thf)Sn(2-py ) ] (py = C H N-5-Me), with
3 5 3
1
R
R
paramagnetic nature. The H NMR spectra in C D displayed
6
6
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 14101–14106 | 14103

View Article Online
The obtained adducts can be used for lanthanoid(II) metal
coordination via lithium salt elimination reactions, leading to
R
complexes [Ln{Sn(2-py ) MEt } ] (Ln = Eu) with the lantha-
3
3 2
noid cation fully encapsulated by two tris(2-pyridyl) stannate
units and the Sn–M bonds being retained. It is of interest that the
dual functionality of a bulky tris(2-pyridyl) stannate ligand
enables subsequent alkyl alane coordination starting from the
corresponding lanthanoid(II) bis(stannate) precursor [Ln{Sn(2-
R
R
py ) } ] (Ln = Yb; py = C H N-3-Me). As a result the for-
3
2
5 3
R
mation of a similar complex [Ln{Sn(2-py ) AlMe } ] was
3
3 2
achieved.
The tin–group 13 element bonds are rather long for all
described complexes, so that these bonds have to be considered
weak. The indium complexes exhibit the first structurally charac-
terised examples of such a bond in a molecular compound.
Fig. 3 Thermal ellipsoid plot (30% probability surface) of the molecu-
R
lar structure of [Eu{Sn(2-py )
3 3 2
InEt } ] (7); hydrogen atoms have been
omitted for clarity. Selected bond lengths (Å) and angles (°): Eu(1)–N(1)
Experimental section
2.596(3), Eu(1)–N(2) 2.599(3), Eu(1)–N(3) 2.582(3), Sn(1)–In(1)
2.8886(4), Sn(1)⋯Eu(1) 3.8823(3), Sn(1)–C(1) 2.209(4), Sn(1)–C(7)
2.206(3), Sn(1)–C(13) 2.208(3), In(1)–C(19) 2.204(4), In(1)–C(21)
2.206(5), In(1)–C(23) 2.211(5), N–Eu–Ncis 84.1(1)–95.5(1), N–Eu–
General considerations
All manipulations were performed using Schlenk line techniques
under an atmosphere of dry nitrogen. Toluene and THF were
N
trans 172.7(1)–179.4(2), C(1)–Sn(1)–C(7) 98.5(1), C(1)–Sn(1)–C(13)
9.3(1), C(7)–Sn(1)–C(13) 100.9(1), C(19)–In(1)–C(21) 114.5(2), C
19)–In(1)–C(23) 111.2(3), C(21)–In(1)–C(23) 117.9(2); equivalent
atoms generated by −x + 1, y, −z + 3/2; selected bond lengths (Å) and
1
5
9
(
dried over Na–benzophenone. Triethylgallium and triethylin-
16
dium were synthesized according to literature procedures. Tri-
1
13
1
7
methylaluminum was used as purchased. H, C{ H}, Li and
R
angles (°) for [Eu{Sn(2-py )
3
3
GaEt }
2
] (6): Eu(1)–N(1) 2.628(3), Eu(1)–
119
1
Sn{ H} NMR spectra were recorded on a Bruker DPX400
spectrometer. The chemical shifts (δ) were referenced to the
N(2) 2.618(3), Eu(1)–N(3) 2.605(3), Sn(1)–Ga(1) 2.7304(4), Sn(1)⋯
Eu(1) 3.8798(2), Sn(1)–C(1) 2.208(3), Sn(1)–C(7) 2.204(3), Sn(1)–C
17
unified scale by using tetramethylsilane as an internal standard.
(
(
13) 2.203(3), Ga(1)–C(19) 2.014(3), Ga(1)–C(21) 2.006(3), Ga(1)–C
23) 2.009(3), N–Eu–Ncis 84.3(1)–106.5(1), N–Eu–Ntrans 168.2(1)–
Melting points were determined in sealed glass capillaries under
a nitrogen atmosphere and are uncorrected. Mass spectra were
recorded using a Thermo Fischer MAT 8230 Mass spectrometer.
CHN analyses were detected on a Vario EL III CHNS
instrument.
1
77.3(1), C(1)–Sn(1)–C(7) 98.6(1), C(1)–Sn(1)–C(13) 97.9(1), C(7)–
Sn(1)–C(13) 104.7(1), C(19)–Ga(1)–C(21) 109.3(1), C(19)–Ga(1)–C(23)
17.1(1), C(21)–Ga(1)–C(23) 114.1(2); equivalent atoms generated by
x + 1, y, −z + 1/2.
1
−
R
R
Preparation of [Li(thf)Sn(2-py )
3 5 3
] (py = C H N-5-Me (1),
C H N-3-Me (2)). To a solution of 2-Br-C H N-5-Me (3.95 g,
5 3
5
3
2
(
3 mmol) in diethyl ether (30 mL) was added a solution of PhLi
11.5 mL, 2.0 M) in dibutyl ether at −50 °C. After 1 h of stirring
Sn{N(SiMe ) } (3.37 g, 7.7 mmol) was added. The reaction
3
2 2
was allowed to warm up to room temperature and thf-free
product 1 precipitated as an ochre coloured solid. The suspen-
sion was filtered, the crude product 1 was washed two times
with n-hexane (30 mL) and dissolved in THF (20 mL). Concen-
tration of the solution and storage at 4 °C overnight yielded
yellow crystals of 1 (3.09 g, 85%). Mp: 247 °C (decomposition);
elemental analysis calcd (%) for C H N OLiSn: C 55.74,
22 26 3
H 5.53, N 8.86; found: C 55.66, H 5.49, N 9.06; NMR (d -THF,
8
Fig. 4 Thermal ellipsoid plot (30% probability surface) of the molecu-
1
TMS, 298 K): H (400.1 MHz), δ = 1.76 (4H, CH ; thf), 2.13
2
R
lar structure of [Yb{Sn(2-py )
3
AlMe
3
}
2
] (9); hydrogen atoms have been
3
(
s, 9H; Me), 3.62 (4H, O–CH ; thf), 7.15 (d, J
= 7.2 Hz,
H–H
2
omitted for clarity. Selected bond lengths (Å) and angles (°): Yb(1)–
N(1) 2.490(1), Yb(1)⋯Sn(1) 3.7531(2), Sn(1)–Al(1) 2.8317(10), Sn(1)–
3
3
H; py), 7.71 (d, J
C{ H} (100.6 MHz), δ = 17.4 (Me), 26.3 (CH ; thf), 68.2
= 7.2 Hz, 3H; py), 8.35 ppm (s, 3H; py);
H–H
1
3
1
2
C(1) 2.220(2), Al(1)–C(7) 1.988(2), Cipso–Sn(1)–Cipso 97.78(5), CMe
–
3
(
(
O–CH ; thf), 129.1 (py), 134.0 ( J
= 25.7 Hz; py), 136.1
2
C–Sn
Al(1)–CMe 113.53(5); equivalent atoms generated by b: −y + 1, x − y, z,
c: −x + y + 1, −x + 1, z, ′: −x + 4/3, −y + 2/3, −z + 2/3.
2
1
JC–Sn = 125.5 Hz; py), 142.2 (py) 191.2 ppm ( J
=
C–Sn
7
119
1
3
48.2 Hz; py); Li (155.5 MHz), δ = 2.67 ppm;
149.2 MHz), δ = −181 ppm.
Compound 2 was synthesized similar to 1 starting from 2-Br-
C H N-3-Me in 98% yield. Mp: 217 °C (decomposition);
Sn{ H}
(
selected heavier group 13 alkyl compounds have been carried
out. In the case of MEt (M = Ga or In) the Sn–M bonded
3
5 3
R
adducts [{Li(thf)Sn(2-py ) }MEt ] are formed. In contrast, the
elemental analysis calcd (%) for C H N OLiSn: C 55.74,
22 26 3
3
3
isolation of an analogous aluminium complex was unsuccessful.
H 5.53, N 8.86; found: C 55.71, H 5.41, N 8.99; NMR (d -THF,
8
14104 | Dalton Trans., 2012, 41, 14101–14106
This journal is © The Royal Society of Chemistry 2012

View Article Online
1
TMS, 298 K): H (400.1 MHz), δ = 1.77 (4H, CH ; thf), 2.73
223 °C; elemental analysis calcd (%) for C H N Al: C 64.41,
2
16 24 2
3
(
3
s, 9H; Me), 3.61 (4H, O–CH ; thf), 6.91 (dd, J
H; py), 7.25 (d, J
py); C{ H} (100.6 MHz), δ = 25.2 (Me), 26.3 (CH ; thf), 68.2
O–CH ; thf), 118.9 (py), 132.7 (py), 142.4 ( J
py), 144.7 (py) 193.6 ppm ( J
155.5 MHz), δ = 2.68 ppm;
289 ppm; MS (EI, 70 eV) m/z (%) = 403 [M ] (14), 396
= 7.6 Hz,
H 8.11, N 9.39; found C 64.23, H 8.09, N 9.14; NMR (C D ,
6 6
2
H–H
3
1
= 7.6 Hz, 3H; py), 8.37ppm (br s, 3H;
TMS, 298 K): H (400.1 MHz), δ = −0.01 (s, 12H; AlMe ), 1.59
H–H
2
1
3
1
3 3
H–H
(s, 6H, Me), 6.81 (d, J
8.0 Hz, 2H; py), 8.33 ppm (s, 2H; py); C{ H} (100.6 MHz),
= 8.0 Hz, 2H; py), 7.75 (d, J
=
2
H–H
2
13
1
(
= 59.6 Hz;
2
C–Sn
1
7
= 363.8 Hz; py); Li
δ = −8.4 (AlMe ), 17.6 (Me), 131.9 (py), 134.9 (py), 136.9
C–Sn
19
2
1
1
(
−
Sn{ H} (149.2 MHz), δ =
(py), 146.3 (py), 183.3 (C , py); MS (EI, 70 eV) m/z (%) =
ipso
+
+
5Me
283 [M − Me] (100), 267 [Al Me (2-py )2 − H] (26), 211
[Al (2-py ) ] (10), 190 [Al Me (2-py ) − H] (21), 134
2
2
+
5Me
5Me
[M − Li] (52).
2
2
Me
2
3
5
[
AlMe(2-py )] (31).
R
Preparation of [{LiSn(2-py )
3
}GaEt
3 n
] (3a) and [{Li(thf)Sn(2-
R
py )
was added to a suspension of 1 (1.22 g, 2.56 mmol) in toluene
30 mL) at room temperature. The obtained clear yellow solution
3 3
}GaEt ] (3b). Triethylgallium, GaEt (0.38 mL, 2.56 mmol)
3
R
Preparation of [Eu{Sn(2-py )
3
3 2
GaEt } ] (6). A mixture of 3a
(
0.79 g, 1.41 mmol) and [Eu(Cp*) (OEt )] (0.35 g, 0.71 mmol)
2
2
(
in toluene (20 mL) was stirred overnight at room temperature.
After filtration from precipitated LiCp* the obtained red solution
was concentrated and taken aside yielding red crystals of 6
was immediately concentrated and taken aside yielding colour-
less crystals of 3a (1.35 g, 94%). Mp: 153 °C; elemental analysis
calcd (%) for C H N GaLiSn: C 51.57, H 5.95, N 7.52;
found: C 51.41, H 6.17, N 7.60; NMR (d -toluene, TMS,
98 K): H (400.1 MHz), δ = 1.26 (br s, 6H; Ga–CH CH ), 1.73
2 3
br s, 9H; Ga–CH CH ), 1.90 (br s, 9H, Me), 6.72 (m, 3H; py),
.06 (m, 6H; py); Li (155.5 MHz), δ = 2.82 ppm; Sn{ H}
149.2 MHz), δ = −213 ppm.
Compound 3a (1.0 g) was dissolved in THF (5 mL) and con-
24 33 3
(0.73 g, 82%). Mp: 129 °C; elemental analysis calcd (%) for
8
1
C
48
H
66
N
6
EuGa
Sn
2
2
: C 45.90, H 5.30, N 6.69; found: C 45.81,
2
H 5.37, N 6.67.
(
8
2 3
7
119
1
R
Preparation of [Eu{Sn(2-py ) InEt } ] (7). A mixture of 4
(
3
3 2
(
0.64 g, 0.95 mmol) and [Eu(Cp*) (OEt )] (0.23 g, 0.47 mmol)
2 2
in toluene (20 mL) was stirred overnight at room temperature.
After filtration from precipitated LiCp* the obtained red solution
was concentrated and taken aside yielding 7 as red needles
centrated yielding colourless crystals of 3b (0.71 mg, 63%). Mp:
46 °C; elemental analysis calcd (%) for C H N OGaLiSn:
1
2
8 41 3
C 53.29, H 6.55, N 6.66; found: C 53.41, H 6.60, N 6.43; NMR
1
3
(0.52 g, 81%). Mp: 176 °C; elemental analysis calcd (%) for
(
8
d -THF, TMS, 298 K): H (400.1 MHz), δ = 0.51 (q, J
=
8
H–H
3
C H N EuIn Sn : C 42.83, H 4.94, N 6.24; found: C 42.79,
.0 Hz, 6H; Ga–CH CH ), 1.27 (t, JH–H = 8.0 Hz, 9H;
48 66
6
2
2
2
3
H 5.06, N 6.02.
Ga–CH CH ), 1.75 (4H, CH ; thf), 2.19 (s, 9H, Me), 3.61 (4H,
2
3
2
3
3
O–CH ; thf), 7.30 (d, J
.0 Hz, 3H; py), 8.40 ppm (s, 3H; py); C{ H} (100.6 MHz),
= 8.0 Hz, 3H; py), 7.77 (d, J
=
H–H
2
H–H
1
3
1
R
8
Preparation of [Yb{Sn(2-py ) } ] (8). A solution of [Yb-
3
2
δ = 5.3 (Ga–CH CH ), 14.1 (Ga–CH CH ), 18.3 (Me), 26.3
(Cp*) (OEt )] (0.5 g, 0.93 mmol) in THF (10 mL) was added to
2
3
2
3
2
2
3
(
CH ; thf), 68.2 (O–CH ; thf), 131.1 (py), 135.3 ( J = 34.1
lithium stannate 2 (0.88 g, 1.86 mmol) in THF (10 mL). The
mixture was stirred overnight at room temperature and then
filtered from precipitated LiCp*. After concentration the
filtrate was cooled to 4 °C to yield dark brown crystals of com-
pound 8 (0.82 g, 92%). Mp: 246 °C; elemental analysis
calcd (%) for C H N Sn Yb: C 44.89, H 3.77, N 8.73; found:
2
2
C–Sn
2
Hz; py), 135.8 ( J
= 111.5 Hz; py), 149.8 (py) 180.2 ppm
C–Sn
7
119
1
(
(
Cipso; py); Li (155.5 MHz), δ = 2.48 ppm;
149.2 MHz), δ = −208 ppm.
Sn{ H}
R
Preparation of [{Li(thf)Sn(2-py )
3 3
}InEt ] (4). Triethylindium,
36
36
6
2
InEt (0.46 mL, 2.74 mmol) was added to a suspension of 1
3
C 44.80, H 3.78, N 8.47; NMR (d -toluene, TMS, 298 K):
8
(1.30 g, 2.74 mmol) in toluene (30 mL) at room temperature.
1
3
H (400.1 MHz), δ = 2.86 (s, 18H; Me), 6.27 (dd, J
=
H–H
The obtained clear pale yellow solution was immediately con-
centrated and taken aside yielding colourless crystals of 4
3
7
.2 Hz, 6H; py), 6.97 (d, J
= 7.2 Hz, 6H; py), 7.62 ppm
= 4.9 Hz, 6H; py); C{ H} (100.6 MHz), δ = 24.5
JC–Sn = 146.3 Hz; Me), 119.9 (py), 133.6 (py), 143.9
H–H
13
3
1
(
(
(
(
d, J
H–H
(1.16 g, 63%). Mp: 172 °C; elemental analysis calcd (%) for
3
C H N OInLiSn: C 49.74, H 6.11, N 6.21; found C 50.11, H
2
1
3
2
8 41 3
JC–Sn = 65.2 Hz; py), 145.1 ( J
JC–Sn = 442.3 Hz; py);
= 21.4 Hz; py) 192.5 ppm
Sn{ H} (149.2 MHz), δ =
1
C–Sn
119 1
5
=
.90, N 6.32; NMR (d -THF, TMS, 298 K): H (400.1 MHz), δ
0.51 (q, J
8
3
3
= 8.0 Hz, 6H; In–CH CH ), 1.43 (t, J
=
H–H
H–H
2
3
−
233 ppm.
8
.0 Hz, 9H; In–CH CH ), 1.75 (4H, CH ; thf), (2.19 (s, 9H,
2
3
2
3
Me), 3.61 (4H, O–CH ; thf), 7.33 (d, J
7
= 8.0 Hz, 3H; py),
2
H–H
R
3
13
1
Preparation of [Yb{Sn(2-py ) AlMe } ] (9). [Yb{Sn(2-
3
3 2
.75 (d, J
= 8.0 Hz, 3H; py), 8.41 ppm (s, 3H; py); C{ H}
H–H
3Me
py ) } ] (0.46 g, 0.48 mmol) was dissolved in toluene
3
2
(
100.6 MHz), δ = 2.6 (In–CH CH ), 15.9 (In–CH CH ),
2 3 2 3
(15 mL) and a solution of trimethylaluminum, (AlMe3)2
1
1
1
2
8.3 (Me), 26.3 (CH ; thf), 68.2 (O–CH ; thf), 131.6 (py),
2
2
3
2
(0.48 mL, 2 M) was added at room temperature without stirring.
After 18 h dark brown crystals of compound 9 were isolated
(0.49 g, 92%). Mp: 209 °C; elemental analysis calcd (%) for
C H N Al Sn Yb: C 45.55, H 4.92, N 7.59; found: C 45.39,
35.6 ( J
= 34.3 Hz; py), 135.9 ( J
= 120.0 Hz; py),
C–Sn
C–Sn
7
49.9 (py) 178.7 ppm (Cipso; py); Li (155.5 MHz), δ =
119
1
.50 ppm; Sn{ H} (149.2 MHz), δ = −201 ppm.
4
2
54
6
2
2
R
1
Preparation of [AlMe
2
(2-py )]
2
(5). A solution of trimethyl-
H 5.14, N 7.06; NMR (d -THF, TMS, 298 K): H (400.1 MHz),
8
δ = −0.97 (s, 18H; AlMe ), 2.76 (s, 18H; Me), 6.60 (dd, J
7.6 Hz, 6H; py), 7.31 (d, J
(d, JH–H = 4.9 Hz, 6H; py)
−235 ppm.
3
aluminum, (AlMe ) in heptanes (0.9 mL, 2 M) was added to a
=
3
2
3
H–H
3
suspension of 1 (0.85 g, 1.79 mmol) in toluene (20 mL) at room
temperature. The clear solution obtained was concentrated and
taken aside yielding colourless crystals of 5 (0.20 g, 74%). Mp:
= 7.6 Hz, 6H; py), 7.45 ppm
Sn{ H} (149.2 MHz), δ =
H–H
3
119
1
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 14101–14106 | 14105

View Article Online
Table 1 Summary of crystallographic data for compounds 3a, 3b, 4 and 6, 7 and 9
3
a
3b
4
6
7
9
Empirical formula
C
24
H
33GaLiN
3
Sn
C
28
H
41GaLiN
3
OSn
C
28
H
41InLiN
3
OSn
C
48
H
66EuGa
2
N
6
Sn
2
C
48
H
66EuIn
2
N
6
Sn
2
42 2 6 2
C H54Al N Sn Yb
1107.29
Trigonal
R3ˉ
F
w
558.88
Orthorhombic
Pnma
630.99
Monoclinic
P2
8
676.09
Monoclinic
P2
8
1255.85
Monoclinic
C2/c
1346.05
Monoclinic
C2/c
Crystal system
Space group
Z
1
/c
1
/c
4
4
4
3
a (Å)
b (Å)
c (Å)
α (°)
15.2718(2)
15.6336(3)
10.9156(2)
90
18.5639(8)
21.5517(6)
17.2611(8)
90
18.6509(7)
21.9927(5)
17.3699(6)
90
20.7309(4)
12.1475(2)
20.4128(3)
90
20.7341(4)
12.5374(3)
20.1952(4)
90
14.5590(3)
14.5590(3)
17.5926(6)
90
β (°)
γ (°)
V (Å )
T (K)
90
90
117.100(6)
90
6147.7(4)
180(2)
1.363
1.711
116.967(4)
90
6350.1(4)
240(2)
1.414
1.535
99.906(2)
90
5063.89(15)
130(2)
1.647
3.281
97.908(2)
90
5199.85(19)
130(2)
1.719
3.046
90
120
3229.41(14)
130(2)
1.708
3
2606.13(8)
130(2)
1.424
−3
ρ
calcd (g cm
)
−
1
μ (mm
)
2.006
3.383
Unique rflns (Rint
(reflns I >
)
3621 (0.0277)
0.0324
11 248 (0.0984)
0.0624
11 615 (0.0379)
0.0519
6822 (0.0387)
0.0322
6198 (0.0342)
0.0321
2196 (0.0203)
0.0165
R
1
a
2
σ(I))
2
a
wR (all data)
0.0770
887941
0.1351
887942
0.1249
887943
0.0608
887944
0.0683
887945
0.0456
887946
CCDC
a
2
2
2 2
2 2 1/2
R
1
(F) = {Σ(|F
o
| − |F
c
|)/Σ|F
o
|} for reflections with F
o
> 4(σ(F
o
)). wR
2
(F ) = {Σw(|F
o
c o
| − |F | ) /Σw|F | } where w is the weight given to each
reflection.
Crystal structure determinations
Álvarez and D. Polo, Inorg. Chem., 2012, 51, 2569; (c) J. A. Cabeza,
J. M. Fernández-Colinas, P. Garcia-Álvarez and D. Polo, Inorg. Chem.,
2
012, 51, 3896.
W.-P. Leung, W.-H. Kwok, F. Xue and T. C. W. Mak, J. Am. Chem. Soc.,
997, 119, 1145.
Single crystals were obtained as described above with the syn-
thetic procedures. The crystals were coated with a perfluoropo-
lyether, picked up with a glass fiber and mounted in the cooled
nitrogen stream of the diffractometer. The crystallographic data
were collected on an Xcalibur-S diffractometer (Oxford Diffrac-
3
4
5
6
1
C. Drost, P. B. Hitchcock and M. F. Lappert, Angew. Chem., Int. Ed.,
1999, 38, 1113.
W.-P. Leung, H. Cheng, R.-B. Huang, Q.-C. Yang and T. C. W. Mak,
Chem. Commun., 2000, 451.
(a) C. Drost, P. B. Hitchcock and M. F. Lappert, Organometallics, 1998,
17, 3838; (b) M. Veith and W. Frank, Angew. Chem., Int. Ed. Engl., 1985,
24, 223.
S. P. Green, C. Jones, K.-A. Lippert, D. P. Mills and A. Stasch, Inorg.
Chem., 2006, 45, 7242.
tion) with Mo-K radiation (λ = 0.71073 Å). The structures were
α
2
solved by direct methods and refined on F by full-matrix least-
18
squares (SHELX97) using all unique data. All non-hydrogen
atoms are anisotropic with H atoms included in calculated posi-
tions (riding model). Crystal data and the details of the data col-
lections and refinement are given in Table 1. The ethyl groups in
7
8
(a) M. Veith, S. Weidner, K. Kunze, D. Käfer, J. Hans and V. Huch,
Coord. Chem. Rev., 1994, 137, 297; (b) V. N. Khrustalev, O. V. Chernov,
R. R. Aysin, I. A. Portnyagin, M. S. Nechaev and S. S. Bukalov, Dalton
Trans., 2008, 1140.
(a) L. H. Gade, Eur. J. Inorg. Chem., 2002, 1257; (b) M. Kilian,
H. Wadepohl and L. H. Gade, Eur. J. Inorg. Chem., 2008, 11.
3
a, 3b, 4 and 7 are disordered. Their carbon atoms were refined
in split positions.
9
1
1
0 K. Zeckert, S. Zahn and B. Kirchner, Chem. Commun., 2010, 46, 2638.
1 F. Reichart, M. Kischel and K. Zeckert, Chem.–Eur. J., 2009, 15,
0018.
Acknowledgements
1
The author thanks the Deutsche Forschungsgemeinschaft (DFG,
SPP 1166) for generous financial support and Daniel Fuhrmann
1
2 B. Cordero, V. Gómez, A. E. Platero-Prats, M. Revés, J. Echeverría,
E. Cremades, F. Barragán and S. Alvarez, Dalton Trans., 2008, 2832.
for the synthesis of InEt3.
13 F. Garcia, A. D. Hopkins, R. A. Kowenicki, M. McPartlin, J. S. Silvia,
J. M. Rawson, M. C. Rogers and D. S. Wright, Chem. Commun., 2007,
586.
1
1
4 H. Anane, A. Jarid and A. Boutalib, J. Phys. Chem. A, 1999, 103, 9847.
5 N. Auner, Synthetic Methods of Organometallic and Inorganic Chemistry,
Thieme, New York, 1996, vol. 2.
References
1
(a) M. F. Lappert and R. S. Rowe, Coord. Chem. Rev., 1990, 100, 267;
b) W. Petz, Chem. Rev., 1986, 86, 1019; (c) M. S. Holt, W. L. Wilson
(
16 F. Runge, W. Zimmermann and I. Pfeiffer, Z. Anorg. Allg. Chem., 1951,
267, 37.
17 R. K. Harris, E. D. Becker, S. M. Cabral de Menezes, R. Goodfellow and
P. Granger, Pure Appl. Chem., 2001, 73, 1795.
and J. H. Nelson, Chem. Rev., 1989, 89, 11; (d) D. Agustin and
M. Ehses, C. R. Chim., 2009, 12, 1189; (e) M. Asay, C. Jones and
M. Driess, Chem. Rev., 2011, 111, 354.
2
(a) S. M. Mansell, R. H. Herber, I. Nowik, D. H. Ross, C. A. Russell and
D. F. Wass, Inorg. Chem., 2011, 50, 2252; (b) J. A. Cabeza, P. Garcia-
18 G. M. Sheldrick, SHELXS-97 and SHELXL-97, Programs for Crystal
Structure Analysis, University of Göttingen, Germany, 1997.
14106 | Dalton Trans., 2012, 41, 14101–14106
This journal is © The Royal Society of Chemistry 2012