Synthesis, structure and characterization of [Mg7(μ3-OCH2CH2OMe)6(μ-OCH2CH2OMe)6][Al(n-Bu)4]2 - A cationic heptanuclear magnesium complex consisting of discrete cations and tetrabutylaluminate anions

Article abstract of DOI:10.1016/j.poly.2007.08.039

Dibutylmagnesium (contaminated with Al(n-Bu)₃; n_Mg:n_Al ca. 1:0.2) was found to react with MeOCH₂CH₂OH followed by the addition of PhSCH(Me)Ph in the presence of 0.2 equiv n-butyllithium yielding [Mg₇(μ₃-OCH₂CH₂OMe)₆(μ-OCH₂CH₂OMe)₆][Al(n-Bu)₄]₂ (1) as the principal product (yield 40-45% referred to MeOCH₂CH₂OH). The single-crystal X-ray diffraction analysis revealed that the centrosymmetric cationic heptamagnesium complex is built up from seven edge-shared MgO₆ octahedra. The [Al(n-Bu)₄]^- anions adopt approximately a tetrahedral AlC₄ symmetry. ¹H, ¹³C and ²⁷Al NMR spectroscopic measurements showed that in THF solution the structures both of the heptamagnesium complex and the tetrabutylaluminate anion are preserved and that there are no cation-anion interactions reducing the symmetry. The ²⁷Al resonance (151.6 ppm) was found to be very sharp (w_1/2 = 5 Hz), the coupling constant ¹J(²⁷Al,¹³C) amounts to 72.3 Hz.

Full text of DOI:10.1016/j.poly.2007.08.039

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 151–156
www.elsevier.com/locate/poly
Synthesis, structure and characterization
of [Mg (l -OCH CH OMe) (l-OCH CH OMe) ][Al(n-Bu) ] –
7
3
2
2
6
2
2
6
4 2
A cationic heptanuclear magnesium complex consisting
of discrete cations and tetrabutylaluminate anions
a
b
a
a
a,
*
Matthias Linnert , Clemens Bruhn , Harry Schmidt , Renate Herzog , Dirk Steinborn
a
Institut f u¨ r Chemie, Martin-Luther-Universit a¨ t Halle-Wittenberg, Kurt-Mothes-Straße 2, D-06120 Halle, Germany
Fachbereich 18, Naturwissenschaften, Abt. Metallorganische Chemie, Universit a¨ t Kassel, Heinrich-Plett-Straße 40, D-34132 Kassel, Germany
b
Received 1 August 2007; accepted 30 August 2007
Available online 25 October 2007
Abstract
Dibutylmagnesium (contaminated with Al(n-Bu) ; nMg:nAl ca. 1:0.2) was found to react with MeOCH CH OH followed by the addi-
3
2
2
tion of PhSCH(Me)Ph in the presence of 0.2 equiv n-butyllithium yielding [Mg (l -OCH CH OMe) (l-OCH CH OMe) ][Al(n-Bu) ]
4 2
7
3
2
2
6
2
2
6
(
1) as the principal product (yield 40–45% referred to MeOCH
2
CH
2
OH). The single-crystal X-ray diffraction analysis revealed that
ꢀ
the centrosymmetric cationic heptamagnesium complex is built up from seven edge-shared MgO
adopt approximately a tetrahedral AlC symmetry. H, C and Al NMR spectroscopic measurements showed that in THF solution
6
octahedra. The [Al(n-Bu)
4
]
anions
1
13
27
4
the structures both of the heptamagnesium complex and the tetrabutylaluminate anion are preserved and that there are no cation–anion
2
7
interactions reducing the symmetry. The Al resonance (151.6 ppm) was found to be very sharp (w1/2 = 5 Hz), the coupling constant
1
27
13
J( Al, C) amounts to 72.3 Hz.
2007 Elsevier Ltd. All rights reserved.
ꢀ
2
7
Keywords: Magnesium complexes; Oligonuclear complexes; Alkyl aluminates; Al NMR spectroscopy; Crystal structures
1
. Introduction
([Mg (OCHMeCH OMe) ] [5], [Mg (THFFO) Cl ] [6],
4 2 8 4 6 2
[
Mg (DDBFO) ] [7], [Mg (OMe) (DDBFO) (MeOH) ]
4 8 4 2 6 5
Metal alkoxides – among them magnesium alkoxides –
[7]), the heptanuclear complex [Mg (DDBFO) ][FeCl ]
7 12 4
have drawn increasing attention not only in chemical
vapour decomposition processes but also as catalyst com-
ponents for olefin polymerization or metathesis processes
[8] and bimetallic complexes of the type [Mg (THFFO) X ]
4 6 2
having terminal Ti and Si containing ligands X, respec-
tively [7,9]. In all these complexes the ligands II–IV are
bound with different coordination modes to the magnesium
[
1–4]. In this context, crystalline oligonuclear complexes –
both monometallic and mixed-metal complexes – may have
serious advantages due to their definite stoichiometry and
centres acting as bridging (l ,l), chelating and/or as termi-
nal ligands.
3
structures. In the case of magnesium, bidentate alkoxo
ꢀ
ligands of the types RO
O (I;
= C spacer) have
2
been successfully used to build up oligonulcear magnesium
complexes. Examples are the tetranuclear complexes
O
O
OMe
O
O
O
(
THFFO )
(DDBFO )
*
Corresponding author. Tel.: +49 345 5525620; fax: +49 345 5527028.
E-mail address: dirk.steinborn@chemie.uni-halle.de (D. Steinborn).
II
III
IV
0
277-5387/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.08.039

152
M. Linnert et al. / Polyhedron 27 (2008) 151–156
Here we report on a heptanuclear magnesium complex
plex 1. In tetrahydrofuran complex 1 was found to react
with the most simple bidentate alkoxo ligand of type I,
with iodine with cleavage of the Al–C bonds yielding
ꢀ
namely with the 2-methoxyethoxo ligand (MeOCH -
AlI /I and butyliodide (Scheme 1). Iodometric titration
2
3
ꢀ
CH O ). The complex [Mg (OCH CH OMe) ][Al(n- Bu) ]
(using an excess of I and back titration of the surplus I
2
2
7
2
2
12
4 2
2
(
1) was obtained as the main product in a reaction that was
with Na S O ) exhibited a very good agreement between
2 2 3
directed to the metallation of a thioether using MeOCH2-
the experimentally found consumption of I2 (16.07 ±
0.36 mol I/mol 1) and the calculated one (16.00 mol I/mol
1). Furthermore, the constitution of complex 1 was unam-
biguously proven by the results of microanalysis as well as
CH OMgBu/n-BuLi. As source of the aluminium a severe
2
impurity of, likely, Al(n-Bu) , in the magnesiumdibutyl used
3
has been identified.
1
13
27
by H, C and Al NMR investigations.
2
. Results and discussion
2.2. Structure
2
.1. Synthesis
Crystals of compound 1 consist of tetra(n-butyl)alumi-
With the objective to metallate 1-(phenyl)ethyl phenyl
nate anions and twofold-positively charged [Mg7-
2
+
sulfide (PhSCH(Me)Ph) with MeOCH CH OMgBu yield-
(l -OCH CH OMe) (l-OCH CH OMe) ]
cations that
2
2
3
2
2
6
2
2
6
ing MeOCH CH OMgC(Me)(Ph)SPh, we let react in an
are shown in Fig. 1. Selected bond lengths and angles are
given in Table 1. The filling of the unit cell in crystals of
1 is shown in Fig. 2. There are no specific cation–anion,
cation–cation or anion–anion interactions; the shortest
2
2
one-pot reaction dibutylmagnesium with 2-methoxyethanol
1:1) followed by the addition of 1 equiv. PhSCH(Me)Ph
(
and a substoichiometric amount (0.2 equiv.) of n-butyllithi-
um. The synthesis resulted in the formation of a larger
amount of well-shaped colourless crystals. Unexpectedly,
single-crystal X-ray diffraction measurements revealed
them to have the composition [Mg (l -OCH CH OMe) -
˚
contacts between non-hydrogen atoms are 3.553(4) A
(C3ꢁ ꢁ ꢁC19 ), 3.851(4) A (C2ꢁ ꢁ ꢁC90) and 3.962(5) A
0
˚
˚
0
(C30ꢁ ꢁ ꢁC30 ), respectively.
ꢀ
7
3
2
2
6
The [Al(n-Bu) ] anions adopt approximately a tetrahe-
4
(
l-OCH CH OMe) ][Al(n-Bu) ] (1) consisting of
a
dral AlC4 symmetry; all C–Al–C angles (108.9(1)–
2
2
6
4 2
cationic heptamagnesium complex and tetra(n-butyl)alumi-
nate anions (Scheme 1).
Analytical investigations of all starting materials made
unambiguously clear that the source for the aluminium is
the ‘‘dibutylmagnesium’’ solution in heptane that con-
tained a considerable amount of aluminium (nMg:nAl ca.
110.1(1)ꢁ) are very close to the tetrahedral one. The Al–C
˚
distances range from 2.006(3) to 2.024(3) A (mean value:
˚
2.014 A). They are slightly longer than those in tetracoor-
dinated organoaluminium compounds having the fragment
˚
‘‘Al–R’’ (R = ethyl–butyl): median: 1.972 A, lower/upper
˚
quartile: 1.955/1.991 A, n = 369 (n – number of observa-
1
:0.2) most likely as Al(n-Bu) . Although PhSCH(Me)Ph
tions) [10].
3
is not a constituent part of complex 1, in the absence of
the sulfide no formation of the complex was observed.
All these findings prompted us to investigate the constitu-
tion of complex 1 carefully and independently from the
X-ray crystallographic measurements.
The cation [Mg (l -OCH CH OMe) (l-OCH CH O-
7
3
2
2
6
2
2
2
+
Me)6]
exhibits crystallographically imposed inversion
symmetry; overall, the symmetry is close to the point group
S6. The seven magnesium atoms build up a puckered hexa-
gon with the magnesium atom Mg1 in the centre. Devia-
Complex 1 is a colourless, air- and moisture-sensitive
crystalline substance. It is the main product of the synthe-
sis; the isolated yield of 1 is 40–45% referred to methoxyeth-
anol. Furthermore, 40–45% and about 30% of the total
amount of Al and Mg, respectively, were found in the com-
tions of Mg2–Mg4 from the Mg mean plane are between
7
˚
± 0.1586(8) and ± 0.1595(7) A. All Mgꢁ ꢁ ꢁMg distances
between neighboured magnesium atoms are between
˚
3.1042(8) and 3.135(1) A. Thus, the Mgꢁ ꢁ ꢁMg separation
II
is in a range that is expected for [Mg O ] coordination
6
as found, for example, in the NaCl-type lattice of MgO
˚
(
2.980 A) [11]. Each three of the six Mg–l -O bridging oxy-
3
O
Mg
O
O
gen atoms lie above and below of the Mg plane such that
7
O
O
O
Mg
the central magnesium atom Mg1 adopts approximately an
˚
O
O
O
O
[Al(
n
-Bu) ]
octahedral O coordination (Mg1–O: 2.089(1)–2.099(2) A;
6
O
O
O
O
O
O
4 2
Mg
O
Mg
Mg
O–Mg1–O: 83.34(6)–96.66(6)ꢁ). Each of the six l-O atoms
bridges two peripheral magnesium atoms. Thus, each of
them is coordinated by two l-O and two l -O bridging
atoms as well as by two terminal ether oxygen atoms. Thus,
all magnesium atoms are surrounded by six oxygen atoms
and the Mg O unit is built up by seven MgO octahedra
linked by sharing edges (Fig. 1c). Comparison of the
Mg–O bond lengths revealed the order Mg–l-O
O
O
O
O
Mg
Mg
O
3
O
O
1
7
24
6
1
) + 8 I2
2 Al3+ + 8 I− + 8
n-BuI
1
2
) + H O/H+
2
+
7 Mg2+ + 12 MeOCH CH OH
2
2
˚
˚
(1.979(2)–2.019(2) A) < Mg–l -O (2.080(2)–2.122(2) A) <
3
˚
Scheme 1.
Mg–Oterminal (2.150(2)–2.205(2) A).

M. Linnert et al. / Polyhedron 27 (2008) 151–156
153
C23
O7
O8
Mg4’
C31
C19
Mg2
O9
Al
C27
O5
O10
O6
Mg1
Mg3’
Mg3
O1
O3
Mg4
O2
O11
Mg2’
O4
O12
Fig. 1. Molecular structure of the cation (a) and anion (b) in crystals of [Mg
7
(l
3
-OCH
2
CH
2
OMe)
6
(l-OCH
2
CH
2
OMe)
6
][Al(n-Bu)
4
]
2
(1) (displacement
ellipsoids at 30 % probability; hydrogen atoms of the cation are omitted). (c) Structure of the Mg
octahedra.
7 6
O24 unit in crystals of 1 shown as edge-shared MgO
Table 1
THFFO) (l-THFFO) ][FeCl ] Æ 3CH Cl (2) prepared by
6 6 4 2 2
˚
Selected interatomic distances (in A) and angles (in deg) of 1
the reaction of Mg(THFFO)2 with FeCl Æ 1.5THF [8].
2
Mg(l-O)
The cation in 2 has crystallographically imposed C sym-
metry. It is worth noting that a tetranuclear magnesium
3
Mg2–O7
Mg2–O9
Mg3–O9
2.011(2)
1.987(2)
2.011(2)
Mg3–O11
Mg4–O7
Mg4–O11
1.985(2)
1.979(2)
2.019(2)
0
complex, [Mg (l -OCHMeCH OMe) (l-OCHMeCH O-
4
3
2
2
2
Me) (OCHMeCH OMe) ], has been obtained with the
2
2
2
3
Mg(l -O)
2-methoxypropoxo ligand that is structurally closely anal-
Mg1–O1
Mg1–O3
Mg1–O5
Mg2–O3
Mg2–O5
2.099(2)
2.089(1)
2.094(1)
2.096(2)
2.122(2)
Mg3–O1
Mg3–O5
Mg4–O1
Mg4–O3
2.107(2)
2.080(2)
2.093(2)
2.101(2)
ogous to the ligand in the heptanuclear complex 1 [5]. In
lithium and sodium tetraalkylaluminate complexes
0
(M[AlR ], M = Li, Na; R = Me, Et, n-Pr) cation–anion
4
contacts were found through Al–C–M bridges and/or ago-
stic a-C–Hꢁ ꢁ ꢁM interactions [12–14] and, likely, also in
tetramethylaluminates of K, Rb and Cs [15,16]. On the
other hand, tetraalkylaluminates were found to crystallize
in discrete ions with bulky counter cations such as
[K(pmdta) ][AlMe ] [17], [CoMe (bpy) ][AlEt ] [18] and
Mg(Oterminal
)
0
Mg2–O4
2.150(2)
2.178(2)
2.205(2)
Mg3–O10
Mg4–O2
Mg4–O12
2.160(2)
2.176(2)
2.168(2)
Mg2–O8
Mg3–O6
Mgꢁ ꢁ ꢁMg
2
4
2
2
4
Mg1ꢁ ꢁ ꢁMg4
Mg1ꢁ ꢁ ꢁMg2
Mg1ꢁ ꢁ ꢁMg3
3.1042(8)
3.1349(8)
3.1194(7)
Mg2ꢁ ꢁ ꢁMg3
Mg2ꢁ ꢁ ꢁMg4
Mg3ꢁ ꢁ ꢁMg4
3.128(1)
3.132(1)
3.135(1)
5
[
Yb(g -fluorenyl)(THF) ][AlMe ] [19]. In complex 1, the
4 4
0
bulkiness of the heptamagnesium complex cation having
coordinatively saturated magnesium centres seems to be
decisive to prevent cation–anion interactions. Recently,
the solid-state structure of a complex was reported in which
Al–C
Al–C19
Al–C23
2.016(3)
2.010(4)
Al–C27
Al–C31
2.024(3)
2.006(3)
2
ꢀ
interstitial [Mg(n-Bu)4] dianions within a polycationic
O–Mg–O
network were found [20].
O7–Mg2–O9
O5–Mg2–O4
O8–Mg2–O3
O1–Mg3–O6
166.61(8)
O9–Mg3–O11
O1–Mg4–O12
O2–Mg4–O3
O11–Mg4–O7
168.65(8)
154.36(7)
153.47(7)
169.15(7)
0
0
152.76(7)
153.90(8)
153.64(7)
155.21(7)
2.3. Spectroscopic investigation
0
O5–Mg3–O10
1
13
27
H, C and Al NMR investigations confirm the con-
C–Al–C
stitution of complex 1. All spectra show the expected sig-
C19–Al–C23
C19–Al–C27
C19–Al–C31
109.6(1)
110.1(1)
108.9(1)
C23–Al–C27
C23–Al–C31
C27–Al–C31
109.9(2)
109.4(2)
109.0(1)
1
nals; H NMR signals exhibited the correct intensities.
The assignment of the signals of the tetrabutylaluminate
anion has been established by H,H and H,C COSY exper-
iments. The signal of the a-C atom of the butyl group is
split into six lines of equal intensity as expected for cou-
An analogous heptamagnesium complex with the
bidentate alkoxo ligand THFFO (THFFOH: 2-tetra-
hydrofurfuryl alcohol) has been found in [Mg (l -
§
2
7
pling with one Al nucleus (I = 5/2, nat. abundance:
7
3

154
M. Linnert et al. / Polyhedron 27 (2008) 151–156
C27’
C19’
C31
C23
C31’
C23’
C19
C27
Fig. 2. View of the packing of cations (only the cluster core is shown) and anions in crystals of 1 along the monoclinic b axis.
1
27
13
1
00%), see Fig. 3. The coupling constant J( Al, C) was
line width of only 5 Hz indicates a much longer T relaxa-
2
found to be 72.3 Hz that is fully consistent with that in
tion time. This suggests that the aluminium atom has local
tetrahedral symmetry. The results of the NMR experiments
show that in THF solution the structures both of the
heptamagnesium complex and the tetrabutylaluminate
anion are preserved and that there are no cation–anion
interactions reducing the symmetry.
ꢀ
ꢀ
[
AlEt4] (73.2 Hz) [21] and in [AlMe4] (71.2 Hz) [22].
Due to the very sharp resonance signals (see below), the
Al–C coupling constant could also be obtained from the
1
3
27
C satellites in the Al NMR spectrum.
The chemical shift (151.6 ppm) of the signal in the Al
2
7
NMR spectrum gives proof of tetracoordinated alumin-
ium. Typical shift range of tetracoordinated aluminium is
In conclusion, complex 1 is the first example of an oligo-
nuclear main group metal complex with a tetraalkylalumi-
nate counter anion that crystallizes in discrete ions and one
of the few examples where the high symmetry of the tetra-
alkylaluminate anion is preserved even in THF solution
exhibiting that the molecules exist, most likely, as sol-
vent-separated ion pairs [25].
1
25–180 ppm whereas in three- and fivecoordinated alu-
minium chemical shifts from 210 to 280 ppm and from
00 to 125 ppm, respectively, were found [23]. For quadru-
1
2
7
pole nuclei like Al (I = 5/2) line broadening of NMR res-
onances is characteristic. Only in the case of highly
symmetric ligand spheres, signals with normal line widths
are observed [24]. Thus, the very sharp signal having a half
3. Experimental
3.1. General considerations
All reactions were performed under Ar atmospheres
δ(CH
3
) = 14.9
using standard Schlenk techniques. Toluene and THF were
distilled from Na/benzophenone prior to use. Methoxyeth-
anol was distilled under argon prior to use. NMR spectra
were recorded on Varian VXR 400 and Unity 500 NMR
spectrometers. Chemical shifts are relative to solvent
2
δ(α-CH ) = 12.9
1JAl.C = 72.3 Hz
1
13
signals ( H, C) as internal references and Al(NO ) (1 M
3
3
2
7
in D O) as external reference ( Al), respectively.
2
PhSCH(Me)Ph was prepared according to [26] and n-BuLi
(
Aldrich) was used as supplied. MgBu /Al(n-Bu) was pur-
2 3
chased from Fluka (handled over Aldrich) supplied as di-
butylmagnesium solution (1 M in heptane); the synthesis
of 1 described below was reproducible with different bottles
of the reagent. Hydrolysis of an aliquot followed by evap-
oration of all solvents in vacuo revealed a ratio of nMg:nAl
ca. 1:0.2 (determined by X-ray fluorescence analysis using a
RFA SRS 3000).
1
5.0
14.0
13.0
C
12.0
11.0
δ
1
3
Fig. 3. 101 MHz C NMR spectrum of 1 in THF-d
resonance of the aluminium bound carbon atoms.
8
showing the

M. Linnert et al. / Polyhedron 27 (2008) 151–156
155
3
(
.2. Synthesis of [Mg (OCH CH OMe) ][Al(n- Bu) ]
4 2
Table 2
7
2
2
12
Crystallographic data for complex 1
1)
Empirical formula
Fw
68 2 7 24
C H156Al Mg O
1582.06
To MgBu /Al(n-Bu) (8 mmol) in heptane/toluene
7/15 ml) methoxyethanol (8 mmol) was dropwise added.
2
3
Space group
C2/c (no. 15)
30.923(2)
17.908(1)
16.843(1)
103.922(6)
9053(1)
4
1.161
0.145
3464
1.36–25.00
42698
7968 (Rint = 0.0739)
7968/0/468
0.0517/0.1467
0.0668/0.1548
0.350 and ꢀ0.423
(
˚
a (A)
The reaction mixture was stirred for 20 min at room tem-
perature. Then, PhSCH(Me)Ph (8 mmol) and after
0 min tetrahydrofuran (3 ml) were added by means of
syringes. After about 1 h n-BuLi (1.6 mmol) in n-hexane
1 ml) was dropwise added with stirring. Standing (without
stirring) for 12–24 h resulted in precipitation of well-shaped
colourless crystals that were used for single-crystal X-ray
diffraction measurements or were filtered off, washed with
diethyl ether (5 · 2 ml) and dried in vacuo. Yield: 430–
˚
b (A)
˚
c (A)
1
b (ꢁ)
V (A )
˚
3
Z
(
ꢀ3
)
qcalc (g cm
ꢀ1
)
l(Mo Ka) (mm
F(000)
Scan range (ꢁ)
Reflections collected
Reflections independent
Data/restraints/parameters
R /wR (I > 2r(I))
4
70 mg (40–45% referred to methoxyethanol).
C H Al Mg O (1582.05) requires C 51.62; H 9.94.
6
8
156
2
7
24
1
2
1
Found: C 51.01; H 9.82%. H NMR (THF-d , 400 MHz):
R /wR (all data)
8
1
2
˚
ꢀ3
)
d ꢀ0.43 (br, 2H, a-CH , butyl), 0.81 (t, 3H, CH , butyl),
Largest difference in peak and hole (e A
2
3
1
3
.20 (‘tq’, 2H, c-CH , butyl), 1.35 (br, 2H, b-CH , butyl),
2 2
.48 (‘dd’, 1H, CH ), 3.54 (‘dd’, 1H, CH ), 3.58 (s, 3H,
2
2
model in their calculated positions according to the riding
model and refined isotropically.
OCH ), 3.71 (s, 3H, OCH ), 3.78 (m, 3H, CH ), 3.88
3
3
2
(
‘dd’, 1H, CH ), 3.99 (‘dt’, 1H, CH ), 4.19 (‘dt’, 1H,
2 2
CH ). H,H COSY spectrum revealed that signals at 3.48,
2
Acknowledgement
3
3
.78 (1H), 3.88, 4.19 ppm and at 3.54, 3.78 (2H),
1
3
.99 ppm belong to the same CH CH moiety. C NMR
2
2
27
1
13
The authors thank Prof. H. P o¨ llmann (Institute of Min-
eralogy and Geochemistry of the University of Halle) for
the determination of Mg/Al.
(
THF-d , 101 MHz): d 12.9 (sextet, J( Al, C) = 72.3 Hz,
8
a-CH , butyl), 14.9 (s, CH , butyl), 31.0 (s (br), c-CH ,
2
3
2
butyl), 32.5 (s, b-CH , butyl), 59.4/59.6 (s/s, 2 · OCH ),
2
3
2
7
6
1.9/62.8/75.5/76.6 (s/s/s/s, 4 · CH2). Al NMR (THF-
d8, 130 MHz): d 151.6 (s + d, w1/2 = 5 Hz, J( Al, C) =
1 27 13
Appendix A. Supplementary material
7
1
3 Hz). Two smaller signals (impurities) were found at
51.0 and 152.3 ppm.
CCDC-656051 contains the supplementary crystallo-
graphic data for 1. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.
html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
3
.3. Iodometric titration of 1
Under strictly anaerobic conditions, a Schlenk tube was
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
filled with a standard solution of iodine in THF (25.0 ml;
.025 M), additional THF (200–250 ml) and an ampoule
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.poly.2007.
0
containing 45–75 mg of 1. Then, the ampoule was broken.
After few minutes the Schlenk tube was opened, water (ca.
08.039.
5
0 ml) was added and the excess of iodine was titrated with
References
Na S O (0.05 M) using starch as indicator.
2
2
3
[
[
1] D.C. Bradley, Chem. Rev. 89 (1989) 1317.
2] W.A. Herrmann, N.W. Huber, O. Runte, Angew. Chem. 107 (1995)
3
.4. X-ray crystal structure determination of 1
2
371.
[3] T.P. Hanusa, in: J.A. McCleverty, T.J. Meyer (Eds.), Comprehensive
Intensity data of a suitable crystal (0.54 · 0.53 ·
Coordination Chemistry II, vol. 3, Elsevier/Pergamon, Amsterdam,
2
004, p. 1.
0
.31 mm) were collected on a STOE IPDS2 diffractometer
˚
[4] L. Resconi, J.C. Chadwick, L. Cavallo, in: D.M.P. Mingos, R.H.
Crabtree (Eds.), Comprehensive Organometallic Chemistry III, vol. 4,
Elsevier, Amsterdam, 2007, p. 1006.
5] L. Albaric, N. Hovnanian, A. Julbe, C. Guizard, A. Alvarez-Larena,
J.F. Piniella, Polyhedron 16 (1997) 587.
at 150(2) K with Mo–Ka radiation (0.71073 A, graphite
monochromator). A summary of the crystallographic data,
the data collection parameters, and the refinement param-
eters is given in Table 2. Absorption correction was carried
out numerically (Tmin/Tmax 0.90/0.95). The structure was
solved by direct methods using SHELXS-97 and refined with
[
[
[
[
6] P. Sobota, J. Utko, Z. Janas, S. Szafert, Chem. Commun. (1996)
1
923.
7] P. Sobota, J. Utko, K. Sztajnowska, J. Ejfler, L.B. Jerzykiewicz,
Inorg. Chem. 39 (2000) 235.
8] Z. Janas, L.B. Jerzykiewicz, P. Sobota, J. Utko, New J. Chem. (1999)
185.
2
full-matrix least-squares routines against F using SHELXL-
9
7 [27]. All non-H atoms were refined with anisotropic dis-
placement parameters. The H atoms were added to the

156
M. Linnert et al. / Polyhedron 27 (2008) 151–156
[
9] P. Sobota, J. Utko, J. Ejfler, L.B. Jerzykiewicz, Organometallics 19
2000) 4929.
[19] H. Nakamura, Y. Nakayama, H. Yasuda, T. Maruo, N. Kanehisa, Y.
(
Kai, Organometallics 19 (2000) 5392.
[
[
[
[
[
[
10] Cambridge Structural Database (CSD): Cambridge Crystallographic
Data Centre, University Chemical Laboratory, Cambridge, UK.
11] V.G. Tsirelson, A.S. Avilov, Y.A. Abramov, E.L. Belokoneva, C.R.
Kitaneh, D. Feil, Acta Crystallogr., Sect. B 54 (1998) 8.
[20] P.C. Andrikopoulos, D.R. Armstrong, E. Hevia, A.R. Kennedy, R.E.
Mulvey, C.T. O’Hara, Chem. Commun. (2005) 1131.
[21] H. Gizbar, Y. Vestfrid, O. Chusid, Y. Gofer, H.E. Gottlieb, V.
Marks, D. Aurbach, Organometallics 23 (2004) 3826.
[22] O. Yamamoto, Chem. Lett. (1975) 511.
12] R.L. Gerteis, R.E. Dickerson, T.L. Brown, Inorg. Chem. 3 (1964)
872.
[23] M. Stender, U. Segerer, J. Sieler, E. Hey-Hawkins, Z. Anorg. Allg.
Chem. 624 (1998) 85, and references cited therein.
13] J.H. Medley, F.R. Fronczek, N. Ahmad, M.C. Day, R.D. Rogers,
C.R. Kerr, J.L. Atwood, J. Cryst. Spectr. Res. 15 (1985) 99.
14] A.I. Sizov, T.M. Zvukova, B.M. Bulychev, V.K. Belsky, J. Organo-
met. Chem. 603 (2000) 167.
[24] T.D.W. Claridge, High-resolution NMR Techniques in Organic
Chemistry, Pergamon Press, Amsterdam, 1999, p. 41.
[25] Y. Marcus, G. Hefter, Chem. Rev. 106 (2006) 4585.
[26] A. Sch o¨ berl, A. Wagner, in: E. M u¨ ller (Ed.), Houben-Weyl, Metho-
den der Organischen Chemie, vol. IX, Thieme-Verlag, Stuttgart, 1955,
p. 7, and 97.
15] R. Wolfrum, G. Sauermann, E. Weiss, J. Organomet. Chem. 18
(1969) 27.
[
[
16] C. Schade, P.v. Ragu e´ Schleyer, Adv. Organomet. Chem. 27 (1987) 169.
17] F.J. Craig, A.R. Kennedy, R.E. Mulvey, M.D. Spicer, Chem.
Commun. (1996) 1951.
[27] G.M. Sheldrick, SHELXL-97, Programs for Structure Determination,
University of G o¨ ttingen, G o¨ ttingen, Germany, 1990;
[
18] S. Komiya, T. Yamamoto, A. Yamamoto, Acta Crystallogr., Sect. B
G.M. Sheldrick, SHELXL-97, Programs for Structure Determination,
University of G o¨ ttingen, G o¨ ttingen, Germany, 1997.
35 (1979) 2702.