Heterobimetallic tin(II) oxido clusters of the type [{Sn6(μ3-O)4(μ3-OCH2R)4} {W(CO)5}4] and [{Sn5(μ3-O)2(μ-OCH2R)4(μ3-OCH2R)2}{Fe(CO)4}2]

Article abstract of DOI:10.1016/j.jorganchem.2016.04.026

Reaction of the tin(II) alkoxides bis(2-methoxyphenylmethanolate)tin(II) (1) and bis(2,4-dimethoxyphenylmethanolate)tin(II) (2) with [W(CO)₅(thf)] and [Fe₂(CO)₉], respectively, gave the heterobimetallic tin(II) oxido clusters [{Sn₆(μ₃-O)₄(μ₃-OCH₂R)₄}{W(CO)₅}₄] [3, R[dbnd6]C₆H₄(OCH₃)-2); 4, R[dbnd6]C₆H₃(OCH₃)₂-2,4] and [{Sn₅(μ₃-O)₂(μ-OCH₂R)₄(μ₃-OCH₂R)₂}{Fe(CO)₄}₂] [5, R[dbnd6]C₆H₃(OCH₃)₂-2,4] which were isolated reproducibly with fair yield as a result of partial hydrolysis in the presence of moisture. The metal oxido clusters are composed of polynuclear tin(II) oxido cages entrapped by arylmethanolato ligands and coordinated to metal carbonyl moieties via lone pairs of electrons at tin. The compounds were analyzed by single crystal X-ray diffraction analysis (1, 4·2THF and 5), elemental analyses, ATR-IR spectroscopy and¹H,¹³C{¹H} and¹¹⁹Sn{¹H) NMR spectroscopy in solution as well as in solid state.

Full text of DOI:10.1016/j.jorganchem.2016.04.026

Journal of Organometallic Chemistry xxx (2016) 1e8
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Heterobimetallic tin(II) oxido clusters of the type [{Sn6(m3-O)4(m3
-
OCH R) } {W(CO) } ] and [{Sn (m3-O)2(m-OCH R) (m3-OCH R) }
2
4
5 4
5
2 4 2 2
{
Fe(CO) } ]
4 2
a
a
b
c
c
Lutz Mertens , Christian Leonhardt , Tobias Rüffer , Ana Toma , Cristian Silvestru ,
a, *
Michael Mehring
Technische Universit a€ t Chemnitz, Institut für Chemie, Koordinationschemie, D-09107 Chemnitz, Germany
Technische Universit a€ t Chemnitz, Institut für Chemie, Anorganische Chemie, D-09107 Chemnitz, Germany
Departamentul de Chimie, Centrul de Chimie Supramolecular aꢀ Organic aꢀ s¸ i Organometalic aꢀ (CCSOOM), Facultatea de Chimie s¸ i Inginerie Chimic aꢀ ,
a
b
c
Universitatea Babe s¸ -Bolyai, 400028 Cluj-Napoca, Romania
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 February 2016
Received in revised form
Reaction of the tin(II) alkoxides bis(2-methoxyphenylmethanolate)tin(II) (1) and bis(2,4-
dimethoxyphenylmethanolate)tin(II) (2) with [W(CO)
erobimetallic tin(II) oxido clusters [{Sn -O)
RaC (OCH -2,4] and [{Sn -O) -OCH R)
5
(thf)] and [Fe
-OCH R) }{W(CO)
-OCH R) }{Fe(CO)
2
(CO)
9
], respectively, gave the het-
[3, RaC (OCH )-2); 4,
(OCH -2,4] which
6
(
m
3
4
(
m
3
2
4
5
}
4
]
6
H
4
3
14 April 2016
6
H
3
3
)
2
5
(
m
3
2
(
m
2
4
(
m
3
2
2
4
}
2
] [5, RaC
6
H
3
3 2
)
Accepted 20 April 2016
Available online xxx
Dedicated to Prof. Heinrich Lang on the
occasion of his 60th birthday
were isolated reproducibly with fair yield as a result of partial hydrolysis in the presence of moisture. The
metal oxido clusters are composed of polynuclear tin(II) oxido cages entrapped by arylmethanolato li-
gands and coordinated to metal carbonyl moieties via lone pairs of electrons at tin. The compounds were
analyzed by single crystal X-ray diffraction analysis (1, 4$2THF and 5), elemental analyses, ATR-IR
spectroscopy and 1H, C{ H} and
13
1
119
Sn{ H) NMR spectroscopy in solution as well as in solid state.
1
Keywords:
Tin alkoxides
© 2016 Elsevier B.V. All rights reserved.
Tin oxido clusters
Tin-tungsten complexes
Tin-iron complexes
Hydrolysis
1
. Introduction
in a variety of organic solvents, present an alternative, e.g. in sol-gel
chemistry for thin film formation [7,8]. In addition volatile tin alk-
oxides and oxido alkoxides might be used in technological processes
based on chemical vapor deposition [9e11]. Because of their water
sensitivity tin alkoxides are easily converted into oligomeric tin
oxido alkoxido clusters, which might often be an advantage rather
than a disadvantage for solution-based processes. Small clusters
show increased stability, better handling and often higher solubility
as compared to the parent tin alkoxides. The most prominent cluster
geometry for tin oxido clusters is based on a hexanuclear octahedral
arrangement of tin atoms, which was first reported for the tin(II)
Homo- and heterobimetallic tin oxides have found widespread
applications as, e.g. gas sensors, solar cells, thermoelectric con-
verters, phosphors, coatings, catalysts and anode materials for Li-ion
batteries [1e6]. Production technologies for these materials in water
are promising with regard to large scale, cost efficiency and envi-
ronmental compatibility. However, solution-based approaches to-
wards tin oxide based nanomaterials and coatings starting from tin
salts in aqueous media are difficult to control due to the low solu-
bility of tin oxido hydroxides, which are readily formed in aqueous
solution. Tin alkoxides, which offer the advantage of high solubility
6 3 4 3 4
oxido hydroxido compound [Sn (m -O) (m -OH) ] in 1968. However,
this tin species is of low solubility as a result of lacking solubilizing
alkoxido ligands [12]. Since this study several hexanuclear tin oxido
alkoxides of similar basic structure have been reported, e.g. [Sn
O) -OR) ] (RaMe [9,13,14], Et [9,14], iPr [14], tBu [15], neoPent
[16], CH CH NMe , [9]). Most often these clusters are a result of
partial hydrolysis, but in case of [Sn -O) -OSiMe ] the cluster
forms as result of silylether-elimination starting from
6 3
(m -
*
Corresponding author. Present address: Technische Universit €a t Chemnitz, D-
9107 Chemnitz, Germany.
E-mail addresses: lutz.mertens@chemie.tu-chemnitz.de (L. Mertens), christian.
0
4 3
(m
4
2
2
2
leonhardt@s2005.tu-chemnitz.de
(C.
Leonhardt),
tobias.rueffer@chemie.tu-
6 3
(m
4 3
(m
3 4
)
chemnitz.de (T. Rüffer), atoma@chem.ubbcluj.ro (A. Toma), cristian.silvestru@
ubbcluj.ro (C. Silvestru), michael.mehring@chemie.tu-chemnitz.de (M. Mehring).
a
http://dx.doi.org/10.1016/j.jorganchem.2016.04.026
0
022-328X/© 2016 Elsevier B.V. All rights reserved.
Please cite this article in press as: L. Mertens, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/
j.jorganchem.2016.04.026

2
L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
[
Sn(OSiMe
oxido clusters are realized for example, in [Sn
OR) ] (RaneoPent) [16], and for tin(IV) in [Sn
Bu) (HOiBu) [19], [Sn -O) -OEt) (OEt)
(OH) -OH) -O) {(OCH CH )(OCMe CH
(OAc) (OtBu) [22], [Sn -O)( -OH)(
S) [23] and [Sn12 -O) -O)
] [24]. In addition the mixed valent Sn(II)/Sn(IV) oxido
-O)( -OSiMe )( -OSiMe (OSiMe ] was reported
3
)
2
]
2
[17,18]. Other nuclearities and structures for tin(II)
-O) -OR)
-O)( -OiBu)
-acac)
Noblelight). ATR-FT-IR spectra were recorded with a BioRad FTS-
1
13
5
(
m
m
3
2
(
m
m
4
(
m
3
-
165 spectrometer with a golden gate sample holder. H and
{ H} NMR data were recorded on a Bruker Avance III 500 spec-
trometer at 500.3 and 125.8 MHz and are referenced to SiMe
C
1
2
3
(
3
h
3
(Oi-
2
7
2
]
4 3
(m
2
(m
4
6
(
2
]
[20],
[21],
4
1
19
1
[
[
(
Sn
5
2
(
m
2
(
m
3
]
2
2
2
m
2
2
)
m
2
N}
-OR)
-OH)
4
]
(
d
¼ 0 ppm). For the Sn{ H} NMR spectra the chemical shifts are
Sn
6
O
6
6
6
3
(
3
(
m
3
(OR)
6
(HOR)]
2
-
reported in ppm relative to SnMe
4
(d
¼ 0 ppm) and were recorded
RaCH
2
C
4
H
3
m
2
(m
3
6
(
m
4
(OEt)18
(m
with a Bruker Avance 400 spectrometer at 111.9 MHz. Solid state
NMR measurements were performed at 9.4 T on a Bruker Avance
400 spectrometer equipped with double-tuned probes capable of
magic angle spinning (MAS). C{ H} CP MAS NMR spectroscopy
was accomplished in 4 mm rotors made of zirconium oxide spin-
ning at 12.5 kHz. Cross-polarization with contact times of 3 ms was
used to enhance sensitivity. The recycle delay was 5s. Sn{ H} CP
MAS spectroscopy was performed in 4 mm rotors spinning at
12.5 kHz. The recycle delay was 10 s. The spectra were referenced
with respect to TMS with tetracyclohexylstannane as a secondary
OEt)10(HOEt)
cluster [Sn
18].
The tin(II) oxido alkoxides offer the possibility to bind transi-
4
4
(
m
4
m
3
3
m
)
3 5
3 2
)
13
1
[
tion metal moieties by coordination via the lone pair of electrons
of the tin atom. In principle, tin(II) oxido alkoxides can thus be
used as starting materials to prepare well-defined hetero-
bimetallic clusters which might serve as single source precursors
to heterobimetallic oxide composites. A seminal example for the
post-modification strategy was provided by Sita et al., in 1997.
119
1
13
119
standard (
d
3.6 ppm for C,
d
ꢀ97.3 ppm for Sn). Melting point
Reaction of [Sn
isolation of either [{Sn
{Sn -O) -OSiMe }{Fe(CO)
6
(
m
3
-O)
4
(
m
3
-OSiMe
3
)
4
(
] with [Fe
-OSiMe
2
(CO)
9
] allows the
}] or
evaluation was carried out with a “Melting Point B-540” apparatus
from Büchi. Elementary analyses were determined using a vario
MICRO from Elementar Analysensysteme GmbH. X-ray powder
diffraction measurements were carried out with a STOE-STADI-P
diffractometer equipped with a Germanium(111) monochromator
6
(
m
3
-O)
4
m
3
3
)
4
}{Fe(CO)
4
[
6
(
m
3
4
(
m
3
3
)
4
4
}
2
] [17]. Other examples of
such heterobimetallic clusters were observed as hydrolysis
products starting from mixtures of two metal-containing pre-
*
cursors, e.g. [{Sn
O) -OH) }{W(CO)
OEt) }{W(CO) ] [26], [Sn
{Sn -O) }{Fe(CO)
Currently we are studying molecular precursors of tin and
6
(
m
3
-O)
4
(
m
3
-OH)
[26], [PPh
-O) -OH)
][AgCl [28].
4
}{Mn(CO)
[{Sn
{Cr(CO)
2
Cp }
6
] [25], [{Sn
6
(
(
m
m
3
-
-
and CuK
Single crystal X-ray diffraction data were obtained by using an
Oxford Gemini diffractometer at 110 (1 and 5, CuK
a
a1
radiation (
l
¼ 1.540598 Å, 40 KV, 40 mA).
4
(
m
3
4
5
}
6
]
4
]
2
7
(
m
3
-OH)( -O)
m
3
3
3
3
5
}
7
6
(
m
3
4
(
m
3
4
5
}
6
] [27] and
S
K
*
[
6
(
m
3
8
2
Cp }
6
2
]
2
(
l
¼ 1.54184 Å)) and 100 K (4$2THF, Mo K
a
(
l
¼ 0.71073 Å)). The
structures were solved using SHELXS-2013 and refined by full-
matrix least-squares produced on F using SHELXL-2013 [33]. All
2
germanium with potential for the concept of twin polymeriza-
tion, a process which provides access to novel nanostructured
organic-inorganic hybrid materials composed of metal
oxides and polymers that can be converted into highly porous
materials [23,29,30]. Twin polymerization is defined as
a concerted formation of two polymers in one synthetic step
starting from a single precursor, which typically bears alkoxide
moieties that are suitable for cationic polymerization, e.g. salicyl
alcoholates or arylmethanolates [31]. Here, we report for the first
time on heterobimetallic tin oxido clusters of such arylmetha-
nolates, which were obtained starting from the corresponding
tin(II) alkoxides, e.g. bis(2-methoxyphenylmethanolate)tin(II)
non-hydrogen atoms were refined anisotropically. All hydrogen
atoms were geometrically placed and refined isotropically in riding
modes using default parameters. In case of 4$2THF the atoms
C2eC7, C9 and O6 of one, and the atoms C11eC16, C18 and O8 of a
second benzylmethanolato ligand were individually refined disor-
dered with split occupancies of 0.43/0.57, respectively.
The figures were created with DIAMOND (release 3.1, 2006) [34].
CCDC 1450431 (1), 1450432 (4), 1450433 (5).
2.1. Synthesis of the tin(II)-tungsten oxido clusters 3e5
(
1) and bis(2,4-dimethoxyphenylmethanolate)tin(II) (2). The
6
2.1.1. [{Sn (m
3
-O)
4
(m -OCH
3
2 6 4 3 4 5 4
C H (OCH )-2) }{W(CO) } ] (3)
starting materials 1 and 2 and the tin oxido clusters [{Sn
6
(
(
m
m
3
-
-
-
A solution of [W(CO)
6
] (0.365 g, 1.04 mmol) in 280 ml THF was
O)
OCH
OCH
4
(
m
3
-OCH
2
C
6
H
4
(OCH
-2,4)
-2,4)
3
)-2)
4
}{W(CO)
}{W(CO)
-OCH
5
}
4
]
(3), [{Sn
(4) and [{Sn
(OCH -2,4)
6
(
m
3
-O)
4
3
irradiated with an UV-lamp for 7 h at ambient temperature. The
yellow solution was slowly added to a suspension of bis(2-
methoxyphenylmethanolate)tin(II) (1) (0.410 g, 1.04 mmol) in
20 ml THF and the suspension was left to stir overnight. The reac-
tion mixture was concentrated at reduced pressure until a volume
of 50 ml was obtained. Crystallization from reaction solution by gas
phase diffusion of n-pentane gave compound 3 as pale yellow mi-
2
C
C
6
H
H
3
(OCH
(OCH
3
)
)
2
4
5
}
C
4
]
5
(
m
3
-O)
2
(
m
2
6
3
3
2
4
(
m
3
2
6
H
3
3
)
2
2
{Fe(CO)
4
}
2
]
(
5) were characterized by elemental analyses, ATR-IR spectros-
copy and NMR spectroscopy in solution as well as in solid state
and X-ray single crystal structure analysis (1, 4$2THF and 5, see
Table 1). The syntheses and structures in solution and in the solid
state are discussed.
ꢁ
1
crocrystals. Yield: 0.245 g (54%); decomp. 130 C. H NMR (CDCl
3
,
5
00.3 MHz, TMS) [ppm] 3.80 (s, 3H, CH O), 5.02 (s, 2H, CH ), 6.66
d
3
2
3
3
13
2
. Material and methods
(d, 1H, JH,H ¼ 8.1 Hz), 6.85 (t, 1H, JH,H ¼ 7.4 Hz), 7.20 (m, 2H).
C
1
{
3
H} NMR (125.81 MHz, CDCl3, TMS) d [ppm] 54.3 (OCH ), 65.1
All manipulations were carried out under inert atmosphere (N
2
(CH
2
), 110.4, 121.4, 126.7, 130.9, 131.0, 157.3, 196.5 (eq. CO,
1
183
13
119
119
1
or Ar) using Schlenk techniques. Toluene, n-pentane, n-hexane and
diethyl ether were distilled over sodium. Tetrahydrofuran was dried
twice, first over sodium and then over Na/K alloy. Karl-Fischer
titration of the solvents gave the following water contents: THF
21.0 ppm), toluene (8.6 ppm), n-hexane (1.1 ppm), n-pentane
1.1 ppm). Tungsten hexacarbonyl (ABCR 99%), tin(II) chloride, 2-
J( We C) ¼ 124 Hz), 198.3 (ax. CO).
3
Sn{ H} NMR (CDCl ,
2
117
111.9 MHz, SnMe
4
)
d
[ppm] ꢀ403 [2Sn, J( Sne Sn) ¼ 144 Hz],
, J( Sne Sn) ¼ 144 Hz; J(119Sne W) ¼ 1578 Hz],
2
119
117
1
183
-164 [4Sn
W
(as a result of hydrolysis, other minor signals also occurred with
2
119
117
(
(
main signals at ꢀ347 [0.08: 1 (Sn ), J( Sne Sn) ¼ 114 Hz]
W
2
119
117 13 1
and ꢀ205 [(0.16: 1 (Sn
W
), J( Sne Sn) ¼ 114 Hz]. C{ H} CP MAS
methoxybenzyl
dimethoxybenzaldehyde (Acros Organics 98%) were used without
further purification. Compound 1 [Sn(OCH (OCH )-2) ] and
compound 2 [Sn(OCH (OCH -2,4) ] were synthesized ac-
alcohol
(Alfa
Aesar
98%)
and
2,4-
NMR (100.62 MHz)
d
[ppm] 54.1 (br, CH O), 64.9 (br, CH ), 110.7
3
2
(br), 122.1 (br), 127.4 (br), 130.7 (br, double intensity), 157.7 (br),
2
C
6
H
4
3
2
196.1 br, CO).
C
6
H
3
3
)
2
2
ATR IR [cmꢀ1]:
n
CHasym 2936 (m),
1896 (s), 1603 (m), 1590 (m), 1507 (m), 1491
(m), 1466 (m), 1362 (w), 1320 (w), 1293 (w), 1244 (m), 1178 (w),
C O
nCHsym 2865 (m), n ] 2070 (s),
2
cording to a literature procedure [32]. UV-light irradiation was
executed by a medium pressure mercury vapor lamp (90 V, Heraeus
C O C O
n ] 1989 (w), n ]
Please cite this article in press as: L. Mertens, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/
j.jorganchem.2016.04.026

L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
3
Table 1
Crystal data of compounds 1, 4$2THF and 5.
Compound
1
4$2THF
5
Empirical formula
Formula weight [g/mol]
Temperature (K)
Wavelength (Å)
Crystal system
Space group
C
16
H
18
O
4
Sn
C
64
H
60
O
38Sn
W
6 4
C
62 66 5 2
H O28Sn Fe
392.99
110
1.54184
monoclinic
P2 /c
2884.66
100
0.71073
monoclinic
C2/c
1964.29
110
1.54184
monoclinic
C2/c
1
a (A)
b (A)
c (A)
5.9124(4)
10.7542(8)
24.537(2)
90
96.674(7)
90
1549.5(2)
4
1.685
24.2721(7)
15.6967(3)
25.3331(8)
90
114.292(4)
90
8797.1(5)
4
2.178
6.960
5376
2.90 to 25.00
ꢀ27 ꢂ h ꢂ 28
ꢀ11 ꢂ k ꢂ 18
ꢀ30 ꢂ l ꢂ 30
19755
25.4728(5)
9.2010(2)
29.0478(8)
90
92.446(2)
90
6801.9(3)
4
1.918
18.414
3856
3.05 to 67.73
ꢀ30 ꢂ h ꢂ 22
ꢀ9 ꢂ k ꢂ 10
ꢀ34 ꢂ l ꢂ 26
11965
ꢁ
a
b
c
( )
ꢁ
( )
ꢁ
( )
3
V (A )
Z
D
calcd (g/cm3)
Absorption coefficient [mmꢀ1]
F(000)
13.234
784
ꢁ
Theta range for data collection [ ]
Limiting indices
3.63 to 62.70
ꢀ6 ꢂ h ꢂ 6
ꢀ
10 ꢂ k ꢂ 12
27 ꢂ l ꢂ 28
ꢀ
No. of reflections collected
7721
No. of unique reflections/Rint
2449/0.0697
7726/0.0328
6028/0.0372
2
Final R indices [l > 2
s
(l)]
R
1
¼ 0.0445
wR
¼ 0.1063
¼ 0.0670
wR
R
1
¼ 0.0317
wR
¼ 0.0716
¼ 0.0400
wR
R
1
¼ 0.0609
wR
¼ 0.1613
¼ 0.0688
wR
2
2
2
R indices (all data)
R
1
R
1
R
1
2
¼ 0.1138
2
¼ 0.0747
2
¼ 0.1681
Goodness-of-fit on F2
Largest diff. peak/ hole [eÅꢀ3]
0.912
1.039
1.060
1.393 / ꢀ1.183
1.405 / ꢀ1.205
2.609 / ꢀ1.274
1
(
2
123 (m), 1021 (m), 965 (m), 934 (m), 857 (w), 837 (w), 751 (s), 625
s), Sn-O 563 (s). CHN analysis calcd (%) for C52 : C,
3.8; H, 1.4; found: C, 23.5; H, 1.4.
5.58, AB spin system with
d
A
¼ 5.42 and
d
B
¼ 5.72 (4H, CH
¼ 5.48 and ¼ 5.54
, JH,H ¼ 12.8 Hz), 6.10 (dd, 2H, JH,H ¼ 8.2 Hz, JH,H ¼ 2.2 Hz),
2
,
2
n
H
36
O32Sn
6
W
4
J
H,H ¼ 11.1 Hz), 5.51, AB spin system with
d
A
d
B
2
3
4
(4H, CH
2
3
4
6
J
J
.30 (m, 6H), 6.48 (dd, 2H, JH,H ¼ 8.2 Hz, JH,H ¼ 2.3 Hz), 6.52 (d, 2H,
3
3
H,H ¼ 2.2 Hz), 7.20 (d, 2H,
JH,H ¼ 8.3 Hz), 7.31 (d, 2H,
2
.1.2. [{Sn
Compound 4 was prepared according to the protocol for 3
starting from [W(CO) (0.365 g, 1.04 mmol) and bis(2,4-
dimethoxyphenylmethanolate)tin(II) (2) (0.470 g, 1.04 mmol) in
80 ml THF. After three days, compound 4 crystallized as 4$2THF at
6 3 4 3 2 6 3 3 2 4 5 4
(m -O) (m -OCH C H (OCH ) -2,4) }{W(CO) } ] (4)
3
H,H ¼ 8.2 Hz), 7.45 (d, 2H, 3HH,H ¼ 8.2 Hz). C{ H} NMR
13 1
(
(
(
125.81 MHz, C
6
D
6
, TMS)
), 55.0 (OCH
2 2
CH ), 63.8 (CH ), 98.9, 99.0, 99.6, 103.9, 104.2, 104.4, 121.1, 123.4,
d
[ppm] 54.3 (OCH
3
), 54.4 (OCH
3
), 54.7
6
]
OCH
3
), 54.9 (OCH
3
3
), 55.1 (OCH
3
), 60.6 (CH
2
), 63.3
2
ꢁ
13
1
123.7, 131.7, 132.0, 132.3, 159.1, 159.3, 159.6, 161.7, 161.9, 162.3, 215.8
ambient temperature. Yield: 0.215 g (33%); decomp. 128 C. C{ H}
CP MAS NMR (100.62 MHz) [ppm] 25.3 (CH THF) 54.3 (CH O),
4.8 (CH O, double intensity), 55.7 (CH O), 65.0 (CH ), 65.6, 67.3
OCH THF),100.0,101.0,103.2,103.6,119.3,119.9,131.5,132.0,158.2,
119
1
(
6 6 4
eq. CO), 216.4 (ax. CO). Sn{ H} NMR (C D , 111.9 MHz, SnMe ):
d
2
3
ꢀ
1
d
[ppm] ꢀ445 (2Sn), -396 (1Sn), -74 (2SnFe). ATR IR [cm ]:
n
CHasym
5
(
3
3
2
2
938 (m), CHsym 2841 (m), 2026 (s), 1943 (w), n ]
n
n
C
]
O
n
C
]
O
C O
2
ꢀ
1
1904 (s), 1611 (s), 1586 (s), 1505 (s), 1455 (s), 1437 (m), 1420 (m),
368 (w), 1333 (m), 1287 (s), 1262 (s), 1239 (w), 1208 (s), 1156 (s),
131 (s), 1032 (s), 1009 (s), 978 (s), 963 (s), 930 (s), 918 (s), 833 (m),
159.2, 162.3, 162.8, 195.3e200.5 (br, CO). ATR IR [cm ]:
n
CHasym
1
1
2
936 (m),
n
CHsym 2863 (m),
n
]
C O
2070 (s),
n
]
C O
C O
1983 (m), n ]
1
1
8
C
898 (s), 1613 (m),1588 (m), 1507 (m),1464 (m),1364 (w), 1331 (w),
291 (m), 1266 (m), 1208 (s), 1132 (s), 1028 (s), 961 (m), 932 (m),
33 (m), 617 (s), Sn-O 558 (s). CHN analysis calcd (%) for
: C, 26.7; H, 2.1; found: C, 26.6, H, 2.0.
812 (s), 784 (s), 737 (w), 712 (w), 648, (m),
n
Sn-O 617 (s), 560 (s), 534
28Sn Fe : C, 37.9; H,
(s), 475 (s). CHN analysis calcd (%) for C62
H
66
O
5
2
n
3.4; found: C, 37.6; H, 3.3.
64 60 6 4
H O38Sn W
2
.1.3. [{Sn
OCH (OCH
A solution of [Fe
was added
5
(
m
3
-O)
2
(
m
-OCH
2
C
6
H
3
(OCH
}{Fe(CO) ] (5)
] (0.21 g, 0.59 mmol) in 50 ml of toluene
suspension of bis(2,4-
3
)
2
-2,4)
4
(
m
3
-
3. Results and discussion
2
C
6
H
3
3
)
2
-2,4)
2
4 2
}
2
(CO)
9
The reaction between tin(II) methoxide and two equivalents of
2-methoxybenzyl alcohol and 2,4-dimethoxybenzyl alcohol,
to
a
ꢁ
dimethoxyphenylmethanolate)tin(II) (2) (0.53 g, 1.18 mmol) in
3
respectively,
in
toluene
at
80
C
afforded
and
bis(2-
bis(2,4-
ꢁ
0 ml of toluene. The mixture was heated at 60 C until a clear
methoxyphenylmethanolate)tin(II)
(1)
solution was obtained. After cooling to room temperature the re-
action mixture was filtered over celite and the obtained orange
solution was concentrated at reduced pressure until a volume of
dimethoxyphenylmethanolate)tin(II) (2) (Scheme 1).
Compounds 1 and 2 are poorly soluble in toluene, THF, CHCl
and CH Cl and when left in solution for 2 h in the presence of
3
2
2
3
0 ml was obtained. Finally diffusion of n-hexane via the gas phase
moisture they hydrolyse to give the starting alcohol and insoluble
inorganic material. Single crystals suitable for X-ray diffraction
were obtained after dissolving 1 at 80 C in toluene and cooling of
the solution to room temperature. An one-dimensional (1D) coor-
dination polymer with tetra-coordinated tin atoms is observed in
the crystal of 1, which is a result of the asymmetric bridging
afforded compound 5 after one week as yellow crystals. Yield:
ꢁ
1
ꢁ
0
d
.280 g (60%); decomp. 145 C. H NMR (C
[ppm] 3.20 (s, OCH , 6H), 3.28 (s, OCH , 6H), 3.34 (s, OCH
.35 (s, OCH , 6H), 3.40 (s, OCH , 6H), 3.47 (s, OCH
¼ 4.87 and ¼ 5.07 (4H, CH
6
D
6
, 500.3 MHz, TMS)
3
3
3
, 6H),
3
3
3
3
, 6H), 4.97, AB
spin system with
d
A
d
B
2
2JH,H ¼ 11.5 Hz),
Please cite this article in press as: L. Mertens, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/
j.jorganchem.2016.04.026

4
L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
Scheme 1. Synthesis pathway to the decanuclear heterobimetallic tin(II)-tungsten oxido clusters 3 and 4 and the heptanuclear heterobimetallic tin(II)-iron oxido cluster 5.
behavior of each benzyalcoholato ligand via its oxygen atom (Fig.1).
The covalent and coordinative bond distances [Sn1eO1 2.12(5) Å,
Sn1eO3 2.13(5) Å and Sn1eO1A 2.35(4) Å, Sn1eO3B 2.31(4) Å) and
Two resonance signals at
were observed for 1 and at
ratio) for 2, with the latter being of higher solubility. These values
d
ꢀ272 and ꢀ161 ppm (1:7 integral ratio)
d
ꢀ270 and ꢀ162 ppm (2:9 integral
ꢁ
119
1
OeSneO angles (O1eSn1eO3 91.1(2) and O1AeSn1eO3B
do not correspond to the Sn{ H} NMR chemical shifts in the solid
state, which are located at ca.
ꢀ350 ppm for both compounds as a
result of tetra-coordinated tin atoms. The Sn{ H} NMR signals at
ca.
ꢀ160 ppm are indicative for the presence of two-coordinated
tin atoms whereas those at ca.
ꢀ270 ppm indicate a three-
coordinated SnO core, which most likely results from dimerisa-
tion. Similar chemical shifts were observed for two-coordinated tin
atoms in Sn(OCtBu
ꢀ163 ppm) [38] and three-coordinated tin
atoms in [Sn( -OiPr)(OSiPh )]
ꢀ246 ppm) [39].
Reactions of the tin(II) alkoxides with [W(CO) (thf)] (for 1 and
2) in THF and [Fe (CO) ] in toluene (for 2) did not provide
ꢁ
1
54.8(2) ] are in good agreement with a pseudo trigonal bipyra-
d
119
1
4
midal geometry of the type SnO E that includes a stereochemically
active lone pair of electrons E. The methoxy groups are located at
large distances (Sn/OMe from 4.56 Åe5.80 Å) and thus are not
coordinated to the tin atoms. The structure of 1 in the solid state is
close to that of Sn(OR) [RaneoPent; SneO 2.113(3) e 2.403(3) Å],
2
with slightly elongated intermolecular coordinative SneO bonds in
the latter [16].
d
d
3
3 2
) (d
m
3 2
(d
ATR-IR spectra in the solid state of 1 and 2 are quite similar,
5
revealing characteristic strong absorption bands for 1 and 2 (
n
C-O
2
9
and Sn-O). Absorption bands corresponding to ΟН groups were not
n
heterobimetallic dinuclear coordination complexes but gave
reproducibly the decanuclear tin(II)-tungsten oxido clusters
detected. However in the presence of moisture the alkoxides easily
hydrolyse to the corresponding alcohol. Thus broad and intensive
OH groups were observed after storage of the compounds under
ambient conditions for a couple of minutes.
[{Sn
RaC
cluster
RaC
6
(
m
3
-O)
(OCH
[{Sn
(OCH
4
(
m
)
3
-OCH
2
R)
-2,4] and the heptanuclear tin(II)-iron oxido
-O) -OCH R) -OCH R) }{Fe(CO) [5,
-2,4] in fair yield (3: 54%; 4$2THF: 33%, 5: 60%).
4
}{W(CO)
5
}
4
]
6 4 3
[3, RaC H (OCH )-2; 4,
6
H
3
3
2
5
2
(
m
3
2
(
m
2
4
(
m
3
2
2
4 2
} ]
The assumption that both compounds 1 and 2 exhibit similar
6
H
3
3
)
119
1
molecular structures is corroborated by solid state
MAS NMR. Compound 1 reveals a chemical shift at
ꢀ351 ppm and
compound 2 at environment.
ꢀ350 ppm consistent with a SnO
These values are in a good agreement with those found in case of
tetra-coordinated metal atoms in tin alkoxides, e.g. Sn(OtBu)
Sn{ H} CP
All clusters are a result of partial hydrolysis which is attributed to
residual water in the solvents (THF 21 ppm; toluene 8.6 ppm).
Noteworthy, starting from the suspensions of the tin(II) alkoxides
the reaction mixture turns into a solution only if water is present
but its amount must be kept in the low ppm region to prevent
formation of hydrolysis products of low solubility. When using
lower volumes of THF (30 ml instead of 300 ml) or toluene (20 ml
instead of 80 ml) the alkoxides do not dissolve, but when small
amounts of solvent (ca. 5%) with a higher concentration of water
was added (THF 200 ppm; toluene 65 ppm), the alkoxides
solubilised immediately. When the syntheses were performed
with lower volumes of THF (30 ml with 220 ppm water) and
toluene (20 ml with 65 ppm water) the alkoxides did undergo
d
d
4
4
(
[
(
d
ꢀ367 ppm), Sn(OtPent)
Sn(O -1,2) {SnN(SiMe
SnO N core)] [8,35e37]. In accordance with the literature com-
4
(
d
ꢀ370 ppm) and the tris-stannylene
2
C
6
H
4
2
3
)
2
}
2
] [ core) and 7 ppm
d
ꢀ388 (SnO
4
2
1
3
1
pounds 1 and 2 gave eight and nine C{ H} NMR resonances,
respectively [32]. 1H NMR spectroscopy in solution shows broad
singlet resonance signals for 1 and 2 which point to equilibriums
between monomeric and oligomeric species for both compounds in
1
19
1
3
solution. This assumption is confirmed by Sn{ H} NMR in CDCl .
Please cite this article in press as: L. Mertens, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/
j.jorganchem.2016.04.026

L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
5
Fig. 2. Molecular structure of the heterobimetallic tin(II)-tungsten oxido cluster 4 as
ball-and-stick model. For clarity, all hydrogen atoms are omitted and of disordered
atoms only one atomic position is displayed. Symmetry transformations used to
generate equivalent atoms: ‘A’ ¼ ex þ 1, y, ez þ ½.
Fig. 1. Ball-and-stick model of a fragment of the polymeric chain of 1 (up) and plot of
the packing diagram of 1 (down). For clarity, hydrogen atoms are omitted. Selected
bond lengths [Å] and angles [ ]: Sn1eO1 2.12 (5), Sn1eO3 2.13(5), Sn1eO1A 2.35(4),
ꢁ
Sn1eO3B 2.31(4), O1eSn1eO(3) 91.1(2), O1eSn1eO3B 88.5(2), O1eSn1eO1A 73.6(2),
O3eSn1eO1A 88.8(2), O3eSn1eO3B 73.7(2), O1AeSn1eO3B 154.8(2). Symmetry
transformations used to generate equivalent atoms: ‘A’ ¼ ex þ 1, ey þ 2, ez þ 2.
bonds [Sn3eO1 2.12(4) Å, Sn4eO2 2.12(4) Å] and others, which are
significantly longer [Sn3eO4 2.44(4) Å, Sn4eO3 2.43(4) Å]. The
‘
B’ ¼ ex, ey þ 2, ez þ 2.
5
other tin atoms coordinate each to a W(CO) -unit with bond dis-
tances Sn1eW1 2.727(5) Å and Sn2eW2 2.739(5) Å, which is well
in line with reported tin-tungsten complexes [26,40e47]. As a
result of this interaction and additional intramolecular tin-oxygen
coordination by the alkoxido ligand the coordination geometry of
the tin atoms Sn1 and Sn2 (and the symmetry related tin atoms) is
hydrolysis to give insoluble amorphous materials instead of
clusters. Compounds 3 and 4 were crystallized from THF by
diffusion of n-pentane via the gas phase into a concentrated re-
action solution. For 3 a polycrystalline material was obtained,
which was not suitable for single crystal X-ray diffraction due to
very small domain sizes. By contrast compound 4 gave crystals of
higher quality and structure elucidation revealed the decanuclear
tin(II)-tungsten oxido cluster 4$2THF with disordered benzyl-
methanolato ligands. Both compounds 3 and 4, respectively, are
assumed to form decanuclear tin(II)-tungsten oxido clusters with
a hexanuclear tin(II) oxido core structure embedded by four
tungsten pentacarbonyl units and four alkoxido ligands. In Fig. 2
the molecular structure of 4 is given.
4
best described as mono-capped trigonal bipyramid O/SnO W
(
Fig. 3). The corresponding Sn1ꢀΟ bond distances cover the range
Sn1ꢀΟ1 2.06 (4) Å, Sn1eO2A 2.04 (4) Å, Sn1eO3 2.19(4) Å to
Sn1eO4A 2.51(4) Å and similar values are found for the other
corresponding tin atoms of the octahedron. The additional intra-
molecular tin-oxygen distances related to the ligand are found in
the range from 2.94(5) Å to 2.99(5) Å, which is significantly below
the sum of the van der Waals radii of tin and oxygen [SrvdW(Sn,O)
5
3.69 Å] [48]. The Sn/W(CO) fragments show a distorted octa-
The oxido cluster 4 possesses crystallographically imposed C
symmetry, with the C axis going through the tin atoms Sn3 and
Sn4. The tin(II) oxido core is best described as an octahedron with
3
the tin atoms occupying the corners and four -oxido and four m -
2
hedral symmetry and the OCeWeCO angles are in the range of
2
ꢁ
ꢁ
8
1
7.4(3) ꢀ92.5(3) for the orthogonal groups and in the range of
ꢁ
ꢁ
78.5(3) e179.6(3) for the almost linearly arranged OCeWeCO
groups.
Powder X-ray diffraction analysis of bulk 4$2THF confirms phase
purity and that of bulk 3 confirms its polycrystalline nature. The
H} CP MAS NMR study of the almost insoluble compound 4$2THF
m
3
alkoxido ligands occupying the eight faces. The four bulky alkoxido
ligands are orientated along the crystallographic b-axis and prevent
any additional coordination to Sn3 and Sn4. Thus, these tin atoms
exhibit a distorted pseudo-trigonal bipyramidal coordination ge-
13
C
1
{
shows, as expected from the single crystal X-ray diffraction data,
two environments for the organic ligands and gave 12 resonance
signals for the aromatic carbon atoms, two signals for the methy-
lene groups, three signals (one signal of double intensity due to
4
ometry of the type SnO E including a stereochemically active lone
pair of electrons E. The distortion is manifested in the
ꢁ
O4eSn3eO4A angle of 129.9(2) (apical positions) and by two
types of tin-oxygen distances, corresponding to short equatorial
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j.jorganchem.2016.04.026

6
L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
Fig. 3. The tin(II) oxido alkoxido core in the molecular structure of 4 showing the additional intramolecular tin-oxygen coordination [only the coordinated tungsten atoms are
shown] (left), and the tin(II)-oxygen core with coordinated W(CO)
hydrogen atoms are omitted and of disordered atoms only one atomic position is displayed. Selected bond lengths [Å] and angles [ ]: Sn1eO1 2.06(4), Sn1eO2A 2.04(4), Sn1eO3
5
units for the same compound [the organic part of the alkoxido ligands is not shown) (right). For clarity, all
ꢁ
2.19 (4), Sn1eO4A 2.51(4), Sn2eO1 2.03(4), Sn2eO2A 2.05(4), Sn2eO3 2.49(4), Sn2eO4 2.19(4), Sn3eO1 2.12(4), Sn3eO4 2.44(4), Sn4eO2 2.12(4), Sn4eO3 2.43(4), Sn1eO5 2.94(5),
Sn2eO7 2.99(5), Sn1eW1 2.727(5), Sn2eW2 2.739(5), O1eSn1eO2A 95.7(2), O1eSn1eO3 77.9(2), O1eSn1eO4A 73.4 (1), O2AꢀSn1eO3 78.5(2), O2AꢀSn1eO4A 71.5(2),
O3eSn1eO4A 135.6(1), O1eSn2eO2 95.9(2), O1eSn2eO3 71.7(2), O1eSn2eO4 78.3(2), O2eSn2eO3 73.5(1), O2eSn2eO4 78.4(2), O3eSn2eO4 135.90(1), O1eSn3eO1A 91.1(2),
O1eSn3eO4 71.4(1), O1eSn3eO4A 74.1(1), O4eSn3eO4A 129.9(2), O2eSn4eO2A 92.0(2), O2eSn4eO3 73.8(1), O2eSn4eO3A 71.9(2), O3eSn4eO3A 129.6(2). Symmetry trans-
formations used to generate equivalent atoms: ‘A’ ¼ ex þ 1, y, ez þ ½.
overlap of two signals) for the carbon atoms of the methoxy groups,
two signals for the THF molecules and one broad signal for the
observed for 4$2THF providing further support for our assumption
that compound 3 adopts a similar structure as it is observed for
compound 4. Additionally, the CH analysis of the polycrystalline
material of 3 is in line with the expected composition of a dec-
carbon atoms of the W(CO)
(
(
5
-unit. In comparison to compound 4
single crystals) the 13C{ H} CP MAS NMR spectrum of compound 3
polycrystalline) shows one set of broader signals, that includes 5
1
anuclear Sn
Single crystals of the tin-iron cluster [{Sn -OCH
4 2
(OCH -2,4) -OCH (OCH -2,4) }{Fe(CO) } ] (5)
6 4
W oxido alkoxido cluster.
distinguished resonance signals for the aromatic carbon atoms (one
signal of double intensity due to overlap of two signals), one signal
for the methylene groups, one signal for the methoxy groups and
5
(m
3
-O)
2
(m
2-
C
6
H
3
3
)
2
4
(m
3
2
C
6
H
3
3
)
2
2
suitable for X-ray diffraction analysis were obtained by diffusion of
n-hexane via the gas phase into a concentrated toluene solution.
Phase purity was confirmed by PXRD.
one broad signal for the W(CO)
5
fragments.
H NMR spectroscopic analysis of 3 in CDCl
resonance signals showing an integral ratio of 3:2:1:1:2. The
1
3
solution gave five
13
C
1
{
H} NMR spectrum of 3 in CDCl
3
solution shows one set of reso-
nance signals which indicates that all of the four alkoxido ligands
119
1
are chemical equivalent.
Sn{ H} NMR spectroscopy gave two
signals at
d
ꢀ164 and ꢀ403 ppm with an integral ration of 2:1. The
value of 2J( Sne Sn) ¼ 144 Hz is in good agreement with the
119
117
literature
value
for
2 2 2 5 2
[{Sn (m-OtBu) (OtBu) }{W(CO) } ]
2
119
117
[
J( Sne Sn) ¼ 137 Hz] [45]. In addition the resonance signal at
1 119 183
d
ꢀ164 ppm shows J( Sne W) ¼ 1578 Hz which corresponds to
values as reported for complexes such as [{Sn -OCMe
CH )(OCH CH )NCH CH NMe {W(CO)
J( Sne W) ¼ 1556 Hz] and [{Sn -OtBu)
J( Sne W) ¼ 1485 Hz] [40,45]. The signal is assigned to the
W-coordinated tin atoms whereas the signal at
ꢀ403 ppm is assigned to the tetra-coordinated tin atoms in trans-
position of an elongated octahedral {Sn }-unit. Noteworthy, in the
Sn{ H} NMR spectrum which was measured overnight (9 h)
signals of minor intensity did occur as a result of side reactions such
2
(m
2-
2
2
2
2
2
2
}
2
5 2
} ]
1
119
119
183
183
[
[
2
(m
2 2 5 2
(OtBu) }{W(CO) } ]
1
four (CO)
d
5
6
119
1
119
1
as hydrolysis. One additional pair of
Sn{ H} NMR signals was
observed at
d
ꢀ205 and ꢀ347 ppm with an integral ration of 2:1
2
119
117
and J( Sne Sn) ¼ 114 Hz, which might indicate the formation
of the hexanuclear tin oxido cluster [{Sn -O) -OH)
W(CO) ]. After one week the intensity of the major signals
6
(m
3
4
(m
3
4
}
{
5 4
}
decreased and more than 15 new signals appeared, demonstrating
the hydrolytic instability of 3.
Fig. 4. Molecular structure of the heterobimetallic tin(II)-iron oxido alkoxido cluster 5
in ball-and-stick style. For clarity, all hydrogen atoms are omitted. Symmetry trans-
formations used to generate equivalent atoms: ‘A’ ¼ ex, y, ez þ ½.
The ATR-IR spectrum of 3 shows similar CO absorption bands as
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L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
7
Fig. 5. The tin(II) oxido alkoxido core in the molecular structure of 5 showing the additional intramolecular tin-oxygen coordination [only the coordinated iron atoms are shown]
(
left), and the tin(II)-oxygen core with coordinated Fe(CO)
4
-units for the same compound [the organic part of the alkoxido ligands is not shown) (right). For clarity, all hydrogen
ꢁ
atoms are omitted. For clarity, all hydrogen atoms are omitted. Selected bond length [Å] and angles [ ]: Sn2eO1 2.08(5), Sn2eO2 2.35(6), Sn1eFe1 2.483(1), Sn1eO1 1.99(5),
Sn1eO2 2.54(5), Sn1eO5 2.06(4), Sn1eO8 2.09(5), Sn3eO1 2.12(5), Sn3eO2A 2.30(5), Sn3eO5A 2.18(5), Sn3eO8 2.46(5), O1eSn2eO1A 92.8(3), O1eSn2eO2 74.1(2), O1AeSn2eO2
7
7
3.3(2), O2eSn2eO2A 132.0(3), O1eSn1eO2 71.4(2), O1eSn1eO5 100.2(2), O1eSn1eO8 78.2(2), O2eSn1eO5 69.2(2), O2eSn1eO8 136.7(2), O5eSn1eO8 87.1(2), O1eSn3eO2A
3.8(2), O1eSn3eO5A 94.7(2), O1eSn3eO8 68.0(2), O2AeSn3eO5A 72.2(2), O2AeSn3eO8 130.2(2), O5AeSn3eO8 80.2(2). Symmetry transformations used to generate equivalent
atoms: ‘A’ ¼ ex, y, ez þ ½.
Heptanuclear
symmetry, with the C
crystallographic b-axes (Fig. 4). The inorganic core of 5 contains five
tin atoms that occupy the vertices of a square-pyramidal poly-
5
possesses crystallographically imposed
C
2
(
d
SnFe ꢀ42 ppm) [17]. The tin atom Sn2 which is placed at the top of
the square pyramid gave a chemical shift
ꢀ396 ppm whereas the
tin atoms Sn3 and Sn3A result in a resonance signal at
ꢀ445 ppm.
These values are in accordance with those of [Sn( -OC iPr-2)
ꢀ429, ꢀ490 ppm) and compound 3 ( ꢀ408 ppm) and are typical
for a SnO E coordination environment [51]. However, the upfield
2
axes going through the Sn2 atom along the
d
d
m
6
H
4
2 n
]
hedron and two Fe(CO)
atoms (Figs. 4 and 5). Two
placed above the four trigonal faces and the tin atoms of the basal
plane are bridged by -alkoxido ligands. The tin atoms Sn2 and Sn3
exhibit a distorted pseudo-trigonal bipyramidal coordination ge-
ometry of the type SnO E assuming a stereochemically active lone
pair of electrons E. The tin-oxygen bond distances amount to
Sn2eO1 2.08(5) Å and Sn2eO2 2.35(6) Å for the apical tin atom and
the Sn3 atoms of the square plane show the following SneO dis-
tances: Sn3eO1 2.12(5) Å, Sn3eO2A 2.30(5) Å, Sn3eO5A 2.18(5) Å
and Sn3eO8 2.46(5) Å. In addition the tin atom at the top of the
square pyramid [Sn2$$$O3/O3A 3.17(5) Å] and two tin atoms of the
basal plane [Sn3$$$O6 3.34(5) Å, Sn3A$$$O6A 3.34(5) Å] exhibit
distances to methoxy groups of the ligands that are shorter than the
sum of the van der Waals radii [SrvdW(Sn,O) 3.69 Å] [48], which
might be interpreted as weak intramolecular stabilisation. Two tin
atoms Sn1/Sn1A at trans-basal positions of the polyhedron are
4
-units that are coordinated to two of the tin
(d
d
m
3
-oxido and two -alkoxido ligands are
m
3
4
shift for Sn3 and Sn3A points to additional weak intramolecular
coordination by a methoxy group of an alkoxido ligand. The
assumption of such an intramolecular coordination is also in
accordance with the observation of three sets of resonance signals
m
4
1
for the alkoxido ligands in the H NMR (integral ratio of 1:1:1) and
1
3
1
C{ H} NMR spectra. For the Fe(CO)
4
fragment two signals are
observed in the C{ H} NMR spectrum, one resonance signal for
the equatorial carbon atoms at eq 216.4 ppm and one signal for the
axial carbon atoms at ax 215.8 ppm. Thus we assume that the
molecular structure of compound 5 is retained after dissolution in
13
1
d
d
C
6 6
D .
4
. Conclusion
Starting from the bis(2-methoxyphenylmethanolate)tin(II) (1)
coordinated to Fe(CO)
.483(1) Å, which is comparable with the tin-iron bond lengths, e.g.
in the heptanuclear [{Sn -O) -OSiMe }{Fe(CO) }] [SneFe
.47 (3) Å] [17] or octanuclear [{Sn -O) -OSiMe
Fe(CO) ] [SneFe 2.46(2) Å] [17] tin-iron oxido clusters and other
tin(II)-iron complexes, e.g. [{Sn( -OCMe CH )(OCMe CH
NMe} {Fe(CO) ] [SneFe 2.498(5) Å] [49] and [{SnCl(RNCMe) CH}
Fe(CO) }] [RaC (iPr) e2,6] [SneFe 2.482 (7) Å] [50]. The coor-
4
moieties with a SneFe bond distance of
and
bis(2,4-dimethoxyphenylmethanolate)tin(II)
(2),
2
respectively, the metal carbonyl coordinated tin oxido alkoxido
clusters [{Sn
[
[
2
clusters 3 and 4 are unprecedented representatives of a series of
previously reported hexanuclear tin oxido alkoxido clusters of
6 4 4
the general type [Sn O (OR) ] (RaH, alkyl), which are capable to
coordinate electron deficient metal complexes via lone pairs of
electrons at the Sn(II) atoms. The tin atoms in these clusters build
up an octahedron and in 3 and 4 the tungsten carbonyl fragments
coordinate to tin atoms in the equatorial plane of an elongated
octahedron. Noteworthy, the hydrolysis process to give 3 and 4
must be carefully controlled, because fully dried solvents did
prevent the formation of any complex as a result of the low
solubility of the tin(II) alkoxides. However larger amounts of
water did produce insoluble amorphous compounds. Unexpect-
edly, under similar reaction conditions but in the presence of
6
(m
3
4
(m
3
3
)
4
4
6
(
m
3
-O)
-OCH
-OCH
4
(
m
H
3
-OCH
2
C
6
H
4
(OCH
-2,4) }{W(CO)
-2,4) -OCH
3
)-2)
4
}{W(CO)
5
}
4
]
(3),
and
2
{
6
(
m
3
4
(
m
3
3 4
) }
{Sn
{Sn
6
5
(
(
m
m
3
3
-O)
-O)
4
2
(
(
m
m
3
2
C
C
6
3
(OCH
3
)
2
4
5
}
4
]
(4)
4 2
}
2
6
H
3
(OCH
3
)
2
4
(
m
3
2
C
6
H
3
3 2
(OCH ) -
m
2
2
2
2
)
2 4 2
,4) }{Fe(CO) } ] (5) were synthesized in fair yield. The tin oxido
2
4
}
2
2
{
4
6
H
3
2
dination geometry at Sn1 is best described as distorted trigonal
bipyramidal (SnO Fe core). The Sn/Fe(CO) fragments show a
distorted trigonal bipyramidal geometry and the OCeFeeCO angles
are in the range from 91.3(4) ꢀ92.7(3) and 114.3(4) e124.5(4) .
Compound 5 is soluble in solvents such as benzene, toluene,
chloroform and dichloromethane and the NMR spectra were
4
4
ꢁ
ꢁ
ꢁ
ꢁ
. The 1 Sn{ H} NMR spectrum gave three signals
19
1
recorded in C
at
ꢀ74, ꢀ396 and ꢀ445 ppm with an integral ratio of 2:1:2. The
resonance signal
ꢀ74 ppm is assigned to penta-coordinated Sn(1),
6 6
D
d
d
which is bound to Fe(CO)
4 4
and shows a SnO Fe coordination
environment. The 1 Sn{ H} NMR chemical shift is in agreement
19
1
with the value given by Sita et al. for the tin atoms bound to iron in
the tin-iron oxido cluster [{Sn (m -O) (m -OSiMe ) }{Fe(CO) } ]
6 3 4 3 3 4 4 2
Fe(CO)
Sn
4
ligands a pentanuclear tin oxido core of the type
(OR) ] was observed to which two Fe(CO) moieties are
[
5
O
2
6
4
Please cite this article in press as: L. Mertens, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/
j.jorganchem.2016.04.026

8
L. Mertens et al. / Journal of Organometallic Chemistry xxx (2016) 1e8
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tin oxido clusters. Note, that starting from [Sn
OSiMe
OSiMe
formation of the corresponding hexanuclear tin oxido benzy-
lalcoholate complexes starting from 2 seemed to be likely as well.
In conclusion, despite that a growing number of fully character-
ized tin oxido clusters are known, the prediction of structure
formation as a result of a “controlled” hydrolysis process and
thus “molecular design” of metal oxido clusters is still a great
challenge.
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(
(
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m
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Please cite this article in press as: L. Mertens, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/
j.jorganchem.2016.04.026