A novel route for the preparation of dimeric tetraorganodistannoxanes

Article abstract of DOI:10.1016/S0022-328X(02)01705-9

The reaction of polymeric diorganotin oxides, (R₂SnO)_n (R = Me, Et, n-Bu, n-Oct, c-Hex, i -Pr, Ph), with saturated aqueous NH₄X (X = F, Cl, Br, I, OAc) in refluxing 1,4-dioxane afforded in high yields dimeric tetraorganodistannoxanes, [R₂(X)SnOSn(X)R₂]₂, and in a few cases diorganotin dihalides or diacetates, R₂SnX₂. The reported method appears suitable for the synthesis of fluorinated tetraorganodistannoxanes. Identification of [R₂(OH)SnOSn(X)R₂]₂ (R=n-Bu; X = Cl, Br) and [R₂(OH)SnOSn(X)R₂] [R₂(X)SnOSn(X)R₂] suggest a serial substitution mechanism starting from [R₂(OH)SnOSn(OH)R₂]₂. X-ray crystal structure determinations are reported for [Me₂(AcO)SnOSn(OAc)Me₂]₂ (29a), [i-Pr₂(Br)SnOSn(Br)i-Pr₂]₂ (20a), [c-Hex2 (F)SnOSn(F)c-Hex₂]₂ (5a) and [c-Hex₂(F)SnOSn(Cl)c-Hex₂]₂ (36), respectively. These show the presence of a central (R₂Sn)₂O₂ core that is connected, via the oxygen atoms, to R₂Sn entities. Acetate (29a) or halides (5a, 20a, 36) complete the coordination about the tin centres.

Full text of DOI:10.1016/S0022-328X(02)01705-9

Journal of Organometallic Chemistry 659 (2002) 73ꢁ83
/
www.elsevier.com/locate/jorganchem
A novel route for the preparation of dimeric
tetraorganodistannoxanes
Jens Beckmann a, Dainis Dakternieks a,*, Fong Sheen Kuan a, Edward R.T. Tiekink b,*
a Centre for Chiral and Molecular Technologies, Deakin University, Geelong, Vic. 3217, Australia
b Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
Received 30 May 2002; received in revised form 1 July 2002; accepted 1 July 2002
Abstract
The reaction of polymeric diorganotin oxides, (R2SnO)n (Rꢀ
NH4X (XꢀF, Cl, Br, I, OAc) in refluxing 1,4-dioxane afforded in high yields dimeric tetraorganodistannoxanes,
[R2(X)SnOSn(X)R2]2, and in a few cases diorganotin dihalides or diacetates, R2SnX2. The reported method appears suitable for
the synthesis of fluorinated tetraorganodistannoxanes. Identification of [R2(OH)SnOSn(X)R2]2 (Rꢀn-Bu; XꢀCl, Br) and
/Me, Et, n-Bu, n-Oct, c-Hex, i-Pr, Ph), with saturated aqueous
/
/
/
[R2(OH)SnOSn(X)R2] [R2(X)SnOSn(X)R2] suggest a serial substitution mechanism starting from [R2(OH)SnOSn(OH)R2]2. X-ray
crystal structure determinations are reported for [Me2(AcO)SnOSn(OAc)Me2]2 (29a), [i-Pr2(Br)SnOSn(Br)i-Pr2]2 (20a), [c-
Hex2(F)SnOSn(F)c-Hex2]2 (5a) and [c-Hex2(F)SnOSn(Cl)c-Hex2]2 (36), respectively. These show the presence of a central
(R2Sn)2O2 core that is connected, via the oxygen atoms, to R2Sn entities. Acetate (29a) or halides (5a, 20a, 36) complete the
coordination about the tin centres. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Tin; Tetraorganodistannoxane; 119Sn-NMR spectroscopy; X-ray crystallography
1. Introduction
not always straightforward and requires specific condi-
tions for each product, which are for new systems
Tetraorganodistannoxanes with dimeric ladders struc-
?
unpredictable [5,26ꢁ
the synthesis of derivatives with Xꢀ
/
32]. A more general approach for
YꢀHal is from a
tures [R2(X)SnOSn(Y)R2]2 (R, R?ꢀ
/
alkyl or aryl; Xꢀ
/
/
/
YꢀHal, OH, OR, OSiMe3, OOCR, OSP(OR)2, NO3,
N3, NCS, SH, OReO3, NCO, OB(OR)2, ROO, RSO3,
RS), have been widely exploited over recent years owing
/
reaction between equimolar amounts of diorganotin
oxide and diorganotin dihalide. A shortcoming of this
method is the requirement that the diorganotin oxide
must be sufficiently soluble in organic solvents [33,34].
Furthermore, this method fails to provide fluorinated
tetraorganodistannoxanes, due to the insolubility of
diorganotin difluorides. Consequently, only very few
examples have been reported so far [35].
to their unique structural features (Scheme 1) [1ꢁ10].
/
They are also of interest as highly selective, homoge-
neous catalysts in various organic reactions such as
transesterification, acylation of alcohols, urethane for-
mation and alkyl carbonate synthesis [11ꢁ24]. More
/
recently dimeric tetraorganodistannoxanes bearing per-
fluorinated substituents were used as catalysts in three
liquid phase systems involving fluorinated solvents [25].
In the past, dimeric tetraorganodistannoxanes with X,
Earlier work showed that reaction between diorgano-
tin oxides and ammonium halides in methylcyclohexane
at reflux resulted in formation of diorganotin dihalides
[36].
YꢀHal, OH have been prepared by the partial hydro-
/
In the present work, we report a new and facile way of
lysis of diorganotin dihalides. However, this method is
generating dimeric tetraorganodistannoxanes with Xꢀ
Yꢀhalogen using (R2SnO)n (RꢀMe, Et, n-Bu, n-Oct,
c-Hex, i-Pr, Ph) and a biphasic solvent mixture consist-
ing of saturated aqueous NH4X solution (XꢀF, Cl, Br,
I, OAc) and 1,4-dioxane. Thus, we have been able to
generate a number of already reported as well as some
/
/
/
* Corresponding authors. Present address: Department of
Chemistry, National University of Singapore, Singapore 117543,
Singapore (E.R.T.T.). E-mail sddress: chtert@nus.edu.sg
/
E-mail address: dainis@mail.deakin.edu.au (D. Dakternieks).
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 7 0 5 - 9

74
J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ83
/
reveals for each compound two triplets centred at
19F)ꢀ
771 Hz) and ꢂ159.4 ppm
1795 Hz) for 3a and at ꢂ
1950 Hz) and 212.0
ꢂ
/
142.2 (1J(119SnÃ
(1J(119SnÃ19F)ꢀ
(1J(119SnÃ19F)ꢀ
(1J(119SnÃ19F)ꢀ
/
/
/
/
/
/
237.6
ppm
/
/
ꢂ
/
/
/
783 Hz) for 5a. The observation of
well-resolved triplets for 3a contradicts the results of
Jain et al. who reported a broad signal at ꢂ156 ppm for
/
Scheme 1.
this compound [37].
hitherto unknown dimeric tetraorganodistannoxanes.
Compounds were characterised by 119Sn-NMR spectro-
scopy in solution and in the solid state and in some
representative cases by X-ray crystallography.
2.1.2. Reactions of (R2SnO)n with NH4Cl
The reaction of (R2SnO)n with NH4Cl provided
dimeric tetraorganodistannoxanes [R2(Cl)SnOSn-
(Cl)R2]2 (RꢀMe (8a) [4], Et (9a) [4], n-Bu (10a) [4],
n-Oct (11a), c-Hex (12a)) and diorganotin dichlorides
R2SnCl2 (Rꢀi-Pr (13b) [40], Ph (14b) [41]), respectively.
/
/
2. Results and discussion
In view of the fact that c-Hex groups are bulkier than Ph
groups, the formation of 12a and 14b suggests that not
only the steric demand of the substituents, but also the
group electronegativities of the substituents determines
the favoured product of the reactions.
The course of reaction between (n-Bu2SnO)n and
NH4Cl was monitored using 119Sn-NMR spectroscopy.
A representative sample was taken after 24 h (total
reaction time 48 h), the 119Sn-NMR spectrum (CDCl3)
2.1. Synthetic aspects
The reaction of the diorganotin oxides, (R2SnO)n
Me, Et, n-Bu, n-Oct, c-Hex, i-Pr, Ph), with
Hal, OAc) was performed in
(Rꢀ
/
aqueous NH4X (Xꢀ
/
refluxing dioxane (Eq. (1)). The reactions were usually
complete when all of the polymeric diorganotin oxide
had dissolved (12ꢁ96 h). In most cases pure dimeric
/
of which revealed eight signals between ꢂ
/
80 and ꢂ190
/
tetraorganodistannoxane, [R2(X)SnOSn(X)R2]2 (here-
after denoted with ‘a’) were obtained after standard
work-up and in few cases diorganotin dihalides or
diacetates, R2SnX2 (hereafter denoted with ‘b’), were
obtained in good to high yields. Detailed results are
presented in Table 1 and are discussed below.
ppm (Fig. 1). The connectivity of these signals was
established by 1D and 2D INADEQUATE 119Sn-NMR
spectroscopy. Accordingly, the signals were unambigu-
ously assigned to [n-Bu2(OH)SnOSn(Cl)n-Bu2]2 (10d, d
(
119Sn): ꢂ
Bu2(OH)SnOSn(Cl)n-Bu2][n-Bu2(Cl)SnOSn(Cl)n-Bu2]
(10c, d (119Sn): ꢂ
93.4, ꢂ125.6, ꢂ132.2, ꢂ175.2; total
integral 61%), and [n-Bu2(Cl)SnOSn(Cl)n-Bu2]2 (10a, d
119Sn): ꢂ
90.7, ꢂ139.1; total integral 27%) [42]. The
/
138.8, ꢂ159.8; total integral 12%) [42], [n-
/
/
/
/
/
(
/
/
ð1Þ
coexistence of the latter three tetraorganodistannoxanes
demonstrates that the redistribution reaction between
these species is slow on the 119Sn-NMR time scale [43].
It also suggests that the reaction mechanism appears to
involve the initial formation of tetrahydroxide species
[n-Bu2(OH)SnOSn(OH)n-Bu2]2 from which hydroxides
are replaced in a stepwise fashion by chlorides.
2.1.1. Reactions of (R2SnO)n with NH4F
The reaction of (R2SnO)n with NH4F afforded
dimeric tetraorganodistannoxanes [R2(F)SnOSn(F)R2]2
(Rꢀ
Et, n-Oct, i-Pr and Ph only inseparable mixtures were
obtained. Moreover, for RꢀMe, Et and Ph the low
/
n-Bu (3a) [37], c-Hex (5a)). However, for Rꢀ
/
Me,
2.1.3. Reactions of (R2SnO)n with NH4Br
The reaction of (R2SnO)n with NH4Br produced
/
yield of these mixtures suggests that substantial amounts
of organotin species were not extracted from the
aqueous layers. This observation might be tentatively
attributed to the formation of charged organotin
species, such as [R2SnF3]ꢂ, [(R2SnF2)2F]ꢂ and
tetraorganodistannoxanes [R2(Br)SnOSn(Br)R2]2 (Rꢀ
Et (16a) [3], n-Bu (17a) [3], n-Oct (18a), i-Pr (20a))
and diorganotin dibromides R2SnBr2 (Rꢀc-Hex (19b)
[44], Ph (21b) [41]), respectively. The reaction of
(Me2SnO)n with NH4Br provided a mixture of unknown
products, which could not be separated. The 119Sn-
NMR (CDCl3) spectrum of this mixture revealed 12
/
/
[R2SnF4]2ꢂ [38,39]. For Rꢀ
NMR spectra of the crude mixtures revealed 12 and 17
signals, respectively, in the region between ꢂ15 and
190 ppm.
In CDCl3 solution, [n-Bu2(F)SnOSn(F)n-Bu2]2 (3a)
/
n-Oct and i-Pr the 119Sn-
/
signals between ꢂ
/
131.5 and ꢂ153.5 ppm, which were
/
ꢂ
/
tentatively assigned to pentacoordinate tin atoms.
The course of reaction between (n-Bu2SnO)n and
NH4Br was also monitored using 119Sn-NMR spectro-
scopy. A representative sample was taken after 24 h
and [c-Hex2(F)SnOSn(F)c-Hex2]2 (5a) are unambigu-
ously characterised by 119Sn-NMR spectroscopy, which

J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ
/83
75
Table 1
Details for the preparation of dimeric tetraorganodistannoxanes (‘a’) and diorganotin dihalides or diacetates (‘b’)
Entry NH4X
(R2SnO)n
Time (h)
Product(s)
Yield (%)
.
Melting point (8C)
d (119Sn) (ppm)
a
1
2
F
Me
Et
48
24
48
48
48
20
12
48
24
48
48
24
20
12
48
24
48
48
24
24
12
48
24
60
48
24
20
12
48
24
48
48
24
20
24
Complex mixture
Complex mixture
b
3
n-Bu
n-Oct
c-Hex
i-Pr
Ph
3a
Complex mixture
75
86
115ꢁ/117
ꢂ142.2, ꢂ159.4
ꢂ212.0, ꢂ237.6
c
4
5
5a
Complex mixture
ꢀ295 (dec.)
d
e
6
7
Complex mixture
8a
ꢀ310 (dec.)
ꢀ280
8
Cl
Br
I
Me
Et
82
60
96
92
84
92
95
ꢂ62.6, ꢂ114.4
g
9
9a
10a
168ꢁ
110ꢁ
94ꢁ
ꢀ250 (dec.)
/170
ꢂ89.1, ꢂ137.6
ꢂ91.4, ꢂ140.3
ꢂ90.8, ꢂ138.2
ꢂ139.0, ꢂ202.7
83.5
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
n-Bu
n-Oct
c-Hex
i-Pr
Ph
/111
11a
/95
12a
13b
14b
80ꢁ
41ꢁ
74ꢁ
/
84
42
76
/
ꢂ53.5
f
Me
Complex mixture
/
h
Et
16a
17a
60
95
90
90
80
92
62
176ꢁ/178
ꢂ79.3, ꢂ128.9
ꢂ81.3, ꢂ129.8
ꢂ82.0, ꢂ130.1
62.3
n-Bu
n-Oct
c-Hex
i-Pr
Ph
103ꢁ/104
18a
19b
63ꢁ/64
58ꢁ/59
20a
21b
ꢀ270 (dec.)
110ꢁ114
41ꢁ43
ꢂ91.9, ꢂ144.0
ꢂ81.8
ꢂ159
/
Me
Et
22b
Complex mixture
/
i
n-Bu
n-Oct
c-Hex
i-Pr
Ph
24a
25a
60
80
80
90
85
76
90
120ꢁ/125
ꢂ169.7, ꢂ173.9
ꢂ169.9, ꢂ174.6
2.9
90ꢁ/95
26b
27b
Oil
Oil
31.5
28b
29a
71ꢁ/72
ꢂ243.1
ꢂ171.4, ꢂ184.6
ꢂ171.0
ꢂ205.9, ꢂ220.6/ꢂ156.3
ꢂ206.6, ꢂ221.3/ꢂ151.1
ꢂ215.3
OAc
Me
Et
206ꢁ/210
30b
31a/31b (52:48)
41ꢁ/43
n-Bu
n-Oct
c-Hex
i-Pr
Ph
32b
33b
80
91
89
92
j
50ꢁ/54
34b
35b
38ꢁ/42
ꢂ205.9
ꢂ116.1
120ꢁ/130
a
b
c
d
e
f
Poor yield (see text).
The 119Sn-NMR shows ten signals between the range of ꢂ82.0 and ꢂ140.7 ppm.
Twelve signals between the range of ꢂ140.0 and ꢂ190.0 ppm.
Seventeen signals between the range of ꢂ15.0 and ꢂ25.5 ppm.
Poor yield (see text).
Twelve signals between the range of ꢂ131.5 and ꢂ153.5 ppm.
An additional signal at 89.8 ppm.
An additional signal at 92.4 ppm.
g
h
i
Seven signals between the range of ꢂ31.9 and ꢂ176.5 ppm.
Isolated as water adduct [45].
j
(total reaction time 48 h), the 119Sn-NMR spectrum
(CDCl3) of which revealed eight signals between ꢂ80
and ꢂ181 ppm. The signals were unambiguously
assigned to [n-Bu2(OH)SnOSn(Br)n-Bu2]2 (17d,
119Sn): ꢂ
161.0, ꢂ174.5; total integral 22%) [42], [n-
Bu2(OH)SnOSn(Br)n-Bu2][n-Bu2(Br)SnOSn(Br)n-Bu2]
(17c, d (119Sn): ꢂ
79.8, ꢂ120.9, ꢂ154.6, ꢂ181.4; total
integral 35%), and [n-Bu2(Br)SnOSn(Br)n-Bu2]2 (17a, d
119Sn): ꢂ
81.3, ꢂ129.8; total integral 43%) [42]. These
[n-Bu2(OH)SnOSn(OH)n-Bu2]2 from which hydroxides
are replaced in a stepwise fashion by bromides.
/
/
d
(
/
/
2.1.4. Reactions of (R2SnO)n with NH4I
The reaction of (R2SnO)n with NH4I afforded only
/
/
/
/
dimeric tetraorganodistannoxanes ‘a’ for Rꢀ
(24a) and n-Oct (25a), whereas diorganotin diiodides
‘b’ were isolated for RꢀMe (22b), c-Hex (26b), i-Pr
(27b) and Ph (28b). In the case of RꢀEt, only a
complex mixture was obtained, which could not be
/
n-Bu
(
/
/
/
results also suggest that the reaction mechanism appears
to involve the initial formation of tetrahydroxide species
/

76
J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ83
/
Fig. 1. 119Sn-NMR spectrum (CDCl3) from the reaction of (n-Bu2SnO)n with NH4Cl after 12 h. Signals denoted with ‘10a’, ‘10c’ and ‘10d’ were
assigned to [n-Bu2(Cl)SnOSn(Cl)n-Bu2]2, [n-Bu2(OH)SnOSn(Cl)n-Bu2][n-Bu2(Cl)SnOSn(Cl)n-Bu2] and [n-Bu2(OH)SnOSn(Cl)n-Bu2]2, respectively.
separated. The 119Sn-NMR spectrum of this mixture
revealed seven signals between ꢂ30 and ꢂ200 ppm.
2.1.6. Synthesis of [c-Hex2(F)SnOSn(Cl)c-Hex2]2
(36)
/
/
Recently, redistribution reactions were described
between two symmetric dimeric tetraorganodistannox-
anes, [R2(X)SnOSn(X)R2]2 and [R2(Y)SnOSn(Y)R2]2
[43,37,46,47]. In the example where X and Y represent
2.1.5. Reactions of (R2SnO)n with NH4OAc
The reaction of (R2SnO)n with NH4OAc afforded
only one dimeric tetraorganodistannoxane, namely,
[Me2(AcO)SnOSn(OAc)Me2]2 (29a), and on almost all
other occasions, diorganotin diacetates, R2Sn(OAc)2
a combination of a strong and a weak donor, e.g. Xꢀ
/F,
YꢀCl or XꢀOH, YꢀCl, these reactions quantita-
/
/
/
tively provide unsymmetric dimeric tetraorganodistan-
noxanes, [R2(X)SnOSn(Y)R2]2, whereas equilibria were
observed when X and Y both comprise weak donors,
(Rꢀ
Ph (35b)). For (n-Bu2SnO)n, a mixture of [n-Bu2(A-
cO)SnOSn(OAc)n-Bu2]2 (31a; 205.9,
119Sn):
220.6; total integral 52%) [42] and n-Bu2Sn(OAc)2
(31b; d 156.3; total integral 48%) was
119Sn): ꢂ
obtained. It is worth mentioning that c-Hex2Sn(OAc)2
(33b) was isolated as its water adduct c-Hex2Sn(OAc)2×
/
Et (30b), n-Oct (32b), c-Hex (33b), i-Pr (34b) and
e.g. Xꢀ
/
Cl, YꢀBr. In order to prepare a rare example
/
d
(
ꢂ
/
[37] of dimeric tetraorganodistannoxane containing F
and Cl atoms, [c-Hex2(F)SnOSn(F)c-Hex2]2 (5a) and [c-
Hex2(Cl)SnOSn(Cl)c-Hex2]2 (12a) were reacted provid-
ing [c-Hex2(F)SnOSn(Cl)c-Hex2]2 (36) in almost quan-
titative yields (Eq. (2)).
ꢂ
/
(
/
/
H2O, the molecular structure of which has been
published elsewhere [45]. The coordination number of
ð2Þ
tin in c-Hex2Sn(OAc)2×
reflected in the 119Sn-MAS-NMR resonance being
observed at ꢂ
401.8 ppm. The 119Sn-NMR spectrum
of the c-Hex2Sn(OAc)2×H2O in CDCl3 shows a signal at
215.3 ppm, consistent with pentacoordinate tin atoms
and, indicating dissociation of the water.
/
H2O is seven, which is also
Compound (36) is colourless, high-melting solid,
which is poorly soluble in common organic solvents.
However, it was possible to obtain a 119Sn-NMR
spectrum (d8-toluene) at 100 8C that displays a doublet
/
/
ꢂ
/

J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ
/83
77
and a doublet of doublets centred at ꢂ
/
175.3 ppm
117/119Sn)ꢀ
220
19F)ꢀ
1540 Hz;
Hz;
3J(119SnÃ
32 Hz) of equal intensity (total integral
80%). Additionally, the spectrum shows 15 low intensity
signals between ꢂ135 and ꢂ247 ppm (total integral
2
(1J(119SnÃ
Hz) and
2J(119SnÃ
OSnÃ
19F)ꢀ
/
19F)ꢀ
226.1 ppm (1J(119SnÃ
117/119Sn)ꢀ
221/217
/
1240 Hz; J(119SnÃ
/
OÃ
/
/
ꢂ
/
/
/
/
OÃ
/
/
/
/
/
/
/
20%), which, appear to be systematically related to 36
[48]. No definitive assignment of these signals could be
made. The 19F-NMR spectrum of 36 (d8-toluene, r.t.)
reveals one major signal at
(1J(19FÃ117/119Sn)ꢀ1220 Hz; 1J(19FÃ
Hz) and two minor signals at ꢂ123.2 and 123.5 ppm,
respectively. The 119Sn-MAS-NMR spectrum of 36
shows three signals at ꢂ 1150
183.0 (1J(119SnÃ19F)ꢀ
Hz), ꢂ 1550 Hz) and ꢂ234.0
226.0 (1J(119SnÃ19F)ꢀ
ppm (1J(119SnÃ19F)ꢀ
1630 Hz) with a total manifold
ꢂ
/
124.1 ppm
/
/
/
117/119Sn)ꢀ
/1489
/
/
/
/
/
/
/
/
/
/
integration of 2:1:1. The number of signals is consistent
with the existence of a non-symmetric tetrameric unit or
two independent molecules in the crystallographic unit
cell, each situated about a centre. The crystallographic
study provides evidence for this (see below).
Fig. 3. Molecular structure and crystallographic numbering scheme
employed for compound 20a.
2.2. Molecular structures of dimeric
tetraorganodistannoxanes 29a, 20a, 5a, 36
The molecular structures of 29a, 20a, 5a and 36 are
shown in Figs. 2ꢁ5, respectively, and selected bond
/
lengths and angles are listed in Tables 2 and 3. The
molecular structure of 29a represents a second poly-
morph of the compound with the monoclinic polymorph
also crystallising in a non-centrosymmetric space group
Pa (see Section 3) [49]. Of the structures with the general
formula {[R2Sn(O2CR?)]2O}2 (29a), i.e. with Rꢀ
/
R?ꢀ
/
Fig. 4. Molecular structure and crystallographic numbering scheme
employed for compound 5a.
Me, is an atypical structure, being the sole example of
one of five motifs known for compounds of this type
[50,51]. The structure is constructed about a central
(Me2Sn)2O2 core to which is linked, via the oxygen
atoms, two Me2Sn entities. Further links between the
endo-cyclic Sn(1) and Sn(2) atoms, and exo-cyclic Sn(3)
and Sn(4) atoms, with the exception of the Sn(1) and
Sn(4) pair, are afforded by bidentate bridging acetate
groups that form essentially symmetric SnÃ
/
O bonds.
The coordination geometry about the Sn(4) atom is
Fig. 2. Molecular structure and crystallographic numbering scheme
employed for compound 29a.

78
J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ83
/
Table 2
a
˚
Selected geometric parameters (A, 8) for compound 29a
Bond lengths
Sn(1)ÃO(1)
Sn(1)ÃO(3)
Sn(1)ÃC(10)
Sn(2)ÃO(2)
Sn(2)ÃO(7)
Sn(2)ÃC(12)
Sn(3)ÃO(4)
Sn(3)ÃO(10)i
Sn(3)ÃC(14)
Sn(4)ÃO(8)
Sn(4)ÃC(15)
2.096(11) Sn(1)ÃO(2)
2.303(10) Sn(1)ÃC(9)
2.099(12) Sn(2)ÃO(1)
2.119(10) Sn(2)ÃO(5)
2.329(13) Sn(2)ÃC(11)
2.104(11) Sn(3)ÃO(2)
2.038(10)
2.101(12)
2.073(9)
2.376(10)
2.092(11)
2.049(13)
2.212(9)
2.235(9)
Sn(3)ÃO(6)
2.523(12) Sn(3)ÃC(13)
2.097(14) Sn(4)ÃO(1)
2.219(11) Sn(4)ÃO(9)
2.125(14) Sn(4)ÃC(16)
2.088(14)
2.026(12)
2.229(11)
2.133(16)
Bond angles
O(1)ÃSn(1)ÃO(2)
O(1)ÃSn(1)ÃC(9)
O(2)ÃSn(1)ÃO(3)
O(2)ÃSn(1)ÃC(10)
O(3)ÃSn(1)ÃC(10)
O(1)ÃSn(2)ÃO(2)
O(1)ÃSn(2)ÃO(7)
O(1)ÃSn(2)ÃC(12)
O(2)ÃSn(2)ÃO(7)
O(2)ÃSn(2)ÃC(12)
O(5)ÃSn(2)ÃC(11)
O(7)ÃSn(2)ÃC(11)
C(11)ÃSn(2)ÃC(12)
O(2)ÃSn(3)ÃO(6)
O(2)ÃSn(3)ÃC(13)
O(4)ÃSn(3)ÃO(6)
O(4)ÃSn(3)ÃC(13)
O(6)ÃSn(3)ÃO(10)i
O(6)ÃSn(3)ÃC(14)
O(10)iÃSn(3)ÃC(14)
O(1)ÃSn(4)ÃO(8)
O(1)ÃSn(4)ÃC(15)
O(8)ÃSn(4)ÃO(9)
O(8)ÃSn(4)ÃC(16)
O(9)ÃSn(4)ÃC(16)
Sn(1)ÃO(1)ÃSn(2)
Sn(2)ÃO(1)ÃSn(4)
Sn(1)ÃO(2)ÃSn(3)
Sn(1)ÃO(3)ÃC(1)
Sn(2)ÃO(5)ÃC(3)
Sn(2)ÃO(7)ÃC(5)
Sn(4)ÃO(9)ÃC(7)
77.1(3)
95.6(4)
89.0(4)
105.6(5)
88.7(6)
75.9(3)
88.2(5)
102.2(5)
164.0(5)
99.5(5)
82.4(6)
86.7(7)
155.1(5)
95.6(4)
99.6(5)
170.6(5)
91.4(5)
89.8(4)
91.4(5)
79.9(5)
92.1(4)
112.0(6)
168.7(4)
90.1(6)
99.7(6)
103.2(5)
131.8(5)
128.8(5)
130.6(8)
127.8(9)
O(1)ÃSn(1)ÃO(3)
165.1(4)
100.3(5)
111.8(5)
84.3(4)
O(1)ÃSn(1)ÃC(10)
O(2)ÃSn(1)ÃC(9)
O(3)ÃSn(1)ÃC(9)
C(9)ÃSn(1)ÃC(10)
O(1)ÃSn(2)ÃO(5)
O(1)ÃSn(2)ÃC(11)
O(2)ÃSn(2)ÃO(5)
O(2)ÃSn(2)ÃC(11)
O(5)ÃSn(2)ÃO(7)
O(5)ÃSn(2)ÃC(12)
O(7)ÃSn(2)ÃC(12)
O(2)ÃSn(3)ÃO(4)
O(2)ÃSn(3)ÃO(10)i
O(2)ÃSn(3)ÃC(14)
O(4)ÃSn(3)ÃO(10)i
O(4)ÃSn(3)ÃC(14)
O(6)ÃSn(3)ÃC(13)
O(10)iÃSn(3)ÃC(13)
C(13)ÃSn(3)ÃC(14)
O(1)ÃSn(4)ÃO(9)
O(1)ÃSn(4)ÃC(16)
O(8)ÃSn(4)ÃC(15)
O(9)ÃSn(4)ÃC(15)
C(15)ÃSn(4)ÃC(16)
Sn(1)ÃO(1)ÃSn(4)
Sn(1)ÃO(2)ÃSn(2)
Sn(2)ÃO(2)ÃSn(3)
Sn(3)ÃO(4)ÃC(1)
Sn(3)ÃO(6)ÃC(3)
141.8(5)
162.5(4)
99.6(5)
86.6(4)
97.2(6)
109.3(3)
80.4(6)
82.3(6)
Fig. 5. Molecular structure and crystallographic numbering scheme
employed for one of the two independent molecules of compound 36.
93.8(4)
174.6(3)
100.5(5)
80.9(4)
completed by a monodentate acetate ligand. Bridges
between neighbouring tetrameric units are present so
that the O(10) atom forms an interaction with a
symmetry related Sn(3) atom (symmetry operation:
87.0(5)
86.9(5)
80.1(5)
159.9(7)
79.6(4)
1ꢂ
/
x, 1ꢂ
/
y, 1/2ꢃ
/
z). The Sn(3)Ã
/
O(10) distance of
˚
2.523(12) A is not so much longer than the other SnÃ
Oacetate bond distances, which lie in the range 2.212(9)ꢁ
˚
2.329(13) A, and hence, the structure is properly
/
/
106.9(6)
84.3(6)
91.6(5)
described as polymeric with the chain extending along
the crystallographic z-axis. The Sn(1) and Sn(4) atom
exist in distorted trigonal-bipyramidal geometries with
the O(1) and O(3), and O(1) and O(5) atoms defining the
axial positions, respectively. A close intramolecular
contact between the Sn(1) and O(9) atoms of 2.904(11)
140.8(8)
125.0(4)
103.6(6)
127.6(4)
127.0(9)
123.4(10)
128.6(11)
149.7(10)
130.8(11) Sn(4)ÃO(8)ÃC(5)
108.1(9)
˚
A is not considered to represent a significant bonding
interaction between these atoms but may be responsible
Sn(3)ÃO(10)iÃC(7)i
a
Symmetry operation i, 1ꢂx; 1ꢂy; 1/2ꢃz.
for the expansion of the C(9)Ã
/
Sn(1)Ã
/
C(10) angle to
141.8(5)8. Similarly, a close contact between the Sn(4)
˚
and O(10) atoms of 2.881(11) A is noted which is also
probably responsible for the widening of the C(15)Ã
Sn(4)ÃC(16) angle to 140.8(8)8. By contrast to the
As mentioned above, 29a is one of two polymorphs for
which full structure determinations are available.
In our hands, 29a crystallised as a mixture of different
/
/
trigonal-bipyramidal geometries found for Sn(1) and
Sn(4), a skew-trapezoidal-bipyramidal geometry, de-
fined by a C2O4 donor set, is the best description for
the coordination geometry for the Sn(2) atom where the
polymorphs from a solution of CHCl3ꢁhexane (1:2)
/
within 3 days, as evidenced by the number of 119Sn-
MAS-NMR signals (ca. 6). The exact number of signals
could not be determined owing to problems with over-
lapping spinning sidebands. From this mixture, a crystal
was selected for the X-ray structure analysis, which
showed a new polymorph for 29a. The molecular
structures for the two polymorphs are in essential
agreement with each other. The lack of crystallographic
methyl groups lie over the weaker Sn(2)Ã
/
O(5), O(7)
bonds. A C2O4 donor set is also found about the Sn(3)
atom which tends towards a distorted octahedral
geometry based on a consideration of the angles, the
disparity in the SnÃ
/
O bond distances notwithstanding.

J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ
/83
79
Table 3
Selected geometric parameters (A, 8) for compounds 20a, 5a and 36
˚
a
b
c
20a
5a
36 (molecule a)
36 (molecule b)
Bond lengths
Sn(1)ÃO(1)
Sn(1)ÃO(1)i
Sn(1)ÃX(1)
Sn(1)ÃC(1)
Sn(1)ÃC(a)
Sn(2)ÃO(1)
Sn(2)ÃX(1)
Sn(2)ÃY
2.058(3)
2.161(3)
2.8222(9)
2.167(5)
2.153(6)
2.034(3)
2.9542(17)
2.5995(16)
2.164(7)
2.164(6)
2.042(4)
2.115(4)
2.174(4)
2.128(9)
2.124(9)
2.011(4)
2.241(4)
2.011(4)
2.138(6)
2.142(7)
2.071(4)
2.113(4)
2.157(3)
2.146(7)
2.146(6)
2.023(4)
2.277(4)
2.4541(16)
2.143(6)
2.171(7)
Sn(3)ÃO(2)
Sn(3)ÃO(2)i
Sn(3)ÃF(2)
Sn(3)ÃC(25)
Sn(3)ÃC(31)
Sn(4)ÃO(2)
Sn(4)ÃF(2)
Sn(4)ÃCl(2)
Sn(4)ÃC(37)
Sn(4)ÃC(43)
2.060(4)
2.132(4)
2.170(4)
2.147(6)
2.156(6)
2.021(4)
2.231(4)
2.4443(18)
2.147(5)
2.138(8)
Sn(2)ÃC(b)
Sn(2)ÃC(c)
Bond angles
O(1)ÃSn(1)ÃO(1)i
O(1)ÃSn(1)ÃX(1)
O(1)ÃSn(1)ÃC(1)
O(1)ÃSn(1)ÃC(a)
O(1)iÃSn(1)ÃX(1)
O(1)iÃSn(1)ÃC(1)
O(1)iÃSn(1)ÃC(a)
X(1)ÃSn(1)ÃC(1)
X(1)ÃSn(1)ÃC(a)
C(1)ÃSn(1)ÃC(a)
O(1)ÃSn(2)ÃX(1)
O(1)ÃSn(2)ÃY
74.82(14)
80.24(9)
73.93(18)
72.68(15)
115.6(3)
115.2(4)
146.51(15)
98.3(3)
74.76(18)
73.07(14)
116.3(2)
111.7(3)
147.82(15)
99.8(2)
O(2)ÃSn(3)ÃO(2)i
O(2)ÃSn(3)ÃF(2)
O(2)ÃSn(3)ÃC(25)
O(2)ÃSn(3)ÃC(31)
O(2)iÃSn(3)ÃF(2)
O(2)iÃSn(3)ÃC(25)
O(2)iÃSn(3)ÃC(31)
F(2)ÃSn(3)ÃC(25)
F(2)ÃSn(3)ÃC(31)
C(25)ÃSn(3)ÃC(31)
O(2)ÃSn(4)ÃF(2)
O(2)ÃSn(4)ÃCl(2)
O(2)ÃSn(4)ÃC(37)
O(2)ÃSn(4)ÃC(43)
F(2)ÃSn(4)ÃCl(2)
F(2)ÃSn(4)ÃC(37)
F(2)ÃSn(4)ÃC(43)
Cl(2)ÃSn(4)ÃC(37)
Cl(2)ÃSn(4)ÃC(43)
C(37)ÃSn(4)ÃC(43)
Sn(3)ÃO(2)ÃSn(4)
Sn(3)ÃO(2)ÃSn(4)i
Sn(3)ÃO(2)ÃSn(3)i
Sn(3)ÃF(2)ÃSn(4)
73.76(18)
72.94(14)
112.59(19)
109.9(2)
112.72(19)
111.05(18)
155.06(9)
99.28(18)
98.57(18)
89.95(15)
90.56(16)
135.6(2)
146.70(15)
99.7(2)
101.4(3)
98.2(3)
90.4(3)
103.3(2)
93.5(2)
89.5(2)
102.73(18)
92.8(2)
88.74(19)
136.0(2)
128.7(4)
71.81(15)
84.73(16)
113.3(2)
109.7(3)
156.52(14)
92.9(2)
130.5(3)
71.40(15)
87.12(12)
109.1(2)
115.7(2)
158.49(9)
84.84(19)
91.5(2)
77.35(10)
89.44(10)
113.7(2)
72.35(14)
90.80(12)
111.1(2)
O(1)ÃSn(2)ÃC(b)
O(1)ÃSn(2)ÃC(c)
X(1)ÃSn(2)ÃY
116.48(18)
166.77(2)
86.7(2)
114.5(3)
163.02(10)
86.71(19)
87.7(4)
X(1)ÃSn(2)ÃC(b)
X(1)ÃSn(2)ÃC(c)
YÃSn(2)ÃC(b)
87.15(17)
99.6(2)
89.0(3)
97.5(2)
98.1(3)
103.90(17)
96.9(2)
101.79(17)
97.7(3)
129.7(3)
YÃSn(2)ÃC(c)
98.18(18)
126.5(3)
C(b)ÃSn(2)ÃC(c)
Sn(1)ÃO(1)ÃSn(2)
Sn(1)iÃO(1)ÃSn(2)
Sn(1)ÃO(1)ÃSn(1)i
Sn(1)ÃX(1)ÃSn(2)
135.2(3)
113.9(2)
138.6(2)
106.07(18)
100.64(14)
131.2(2)
114.05(18)
140.7(2)
105.24(18)
101.48(14)
124.71(16)
130.10(17)
105.18(14)
77.69(3)
113.18(17)
140.5(2)
106.24(18)
101.42(13)
Symmetry operation i: ꢂx, ꢂy, ꢂz; 1/2ꢂx, 1/2ꢂy, 1ꢂz; ꢂx, 1ꢂy, ꢂz; ꢂx, ꢂy, ꢂ1ꢂz.
a
XꢀBr; YꢀBr(2); aꢀ4; bꢀ7; cꢀ10.
XꢀF; YꢀF(2); aꢀ7; bꢀ13; cꢀ19.
XꢀF; YꢀCl(1); aꢀ7; bꢀ13; cꢀ19.
b
c
symmetry in 29a is unusual and indeed the remaining
structures of 20a, 5a and 36 are centrosymmetric.
The molecular structure of 20a shows a centrosym-
metric (i-Pr2Sn)2O2 core connected, via the oxygen
atoms, to two i-Pr2Sn entities. Almost symmetric
bromide bridges between the endo- and exo-cyclic tin
135.6(2)8 compared with 126.5(3)8 for C(7)Ã
C(10). The 119Sn-MAS-NMR spectrum of 20a showing
two signals at ꢂ72.0 and ꢂ148.0 ppm, is in agreement
with the centrosymmetric space group found in the X-
ray diffraction experiment. The molecular structure of
the fluoride analogue, 5a, is in essential agreement with
that of 20a.
/
Sn(2)Ã
/
/
/
atoms are present. The Sn(2)Ã
/
bound Br(2) atoms are
terminal in that the intramolecular Sn(1)ꢀ ꢀ ꢀBr(2) separa-
Allowing for the replacement of the bromides by
fluorides and the substitution of the isopropyl substi-
tuents with cyclohexyl, the structure of 5a is as described
above for 20a. The intramolecular Sn(1)ꢀ ꢀ ꢀF(2) separa-
˚
tions of 3.530(3) A are not indicative of significant
bonding interactions between these atoms. The coordi-
nation geometries for the tin atoms are both based on
trigonal-bipyramids. In the case of Sn(1), the O(1) and
Br(1) atoms occupy the axial positions, and two
bromides occupy the axial positions about the Sn(2)
atom. The influence of the close Sn(1)ꢀ ꢀ ꢀBr(2) interac-
˚
tions are 3.472(4) A. The key difference between the two
structures is found in the association of two chloroform
molecules to the tetrameric unit as illustrated in Fig. 4.
Hydrogen bonding interactions between the terminal
˚
tion is such to expand the C(1)Ã
/
Sn(1)Ã
/
C(4) angle to
F(2) atoms are noted so that Hꢀ ꢀ ꢀF(2) is 1.91 A,

80
J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ83
/
˚
C(25)ꢀ ꢀ ꢀF(2) is 2.868(10) A and the angle subtended at
H is 1618. While full details are not reported here, a
preliminary structure of the chloride analogue, 12a, has
been determined. Difficulties in the refinement owing to
the lack of resolution of two cyclohexyl rings preclude a
full report but suffice to say that the structure resembles
very closely the prototype 5a. The final structure
determined is an example of a novel mixed halide, i.e.
36.
3.2. General procedure for the reaction of (R2SnO)n with
NH4X
The organotin oxide, (R2SnO)n, (10.0 mmol, 1.65 g
for Rꢀ
g for Rꢀ
Pr, 2.89 g for Rꢀ
ml) and a saturated aqueous solution (50 ml) of the
appropriate NH4X (XꢀF, Cl, Br, I, OAc) was added.
/
Me, 1.93 g for Rꢀ
n-Oct, 3.01 g for Rꢀ
Ph) was suspended in 1,4-dioxane (50
/
Et, 2.49 g for Rꢀ
/
n-Bu, 3.61
/
/
c-Hex, 2.21 g for Rꢀ
/i-
/
/
The reaction mixture was heated under reflux until all of
the (R2SnO)n had dissolved (cf. Table 1). Then, the
solvent mixture was almost entirely removed in vacuo
The structure of 36 crystallises with two independent
centrosymmetric molecules comprising the asymmetric
unit. One of the molecules is shown in Fig. 5 and the
other is in essential agreement with this. Selected
geometric parameters for both independent molecules
are collected in Table 3. From Fig. 5, it is apparent that
the more electronegative fluorine atoms function as
symmetric bridges between the endo- and exo-cyclic tin
atoms. The chlorine atoms occupy terminal positions
and the resulting residue was extracted with CHCl3 (2ꢄ
/
100 ml). The combined organic extracts were dried over
Na2SO4. After removal of the solvent, a crude product
was obtained, which was recrystallised from
chloroformꢁ/hexane.
For (Me2SnO)n ꢁ/NH4F a complex mixture was ob-
tained (0.33 g). No pure product could be isolated (see
text).
˚
with Sn(1)ꢀ ꢀ ꢀCl(1) being 3.707(3) A and Sn(3)ꢀ ꢀ ꢀCl(2)
˚
being 3.814(3) A, distances again not indicative of
For (Et2SnO)n ꢁNH4F a complex mixture was ob-
/
significant bonding interactions. Very recently, the
crystal structure of the phenyl analogue was reported,
i.e. [Ph2(F)SnOSn(Cl)Ph2]2 [52]. In this structure, the
tained (0.49 g). No pure product could be isolated (see
text).
fluoride bridges are similar with Sn(1)Ã
/
F(1) and Sn(2)Ã
/
˚
F(1) being 2.175(4) and 2.222(5) A, respectively and the
˚
3.2.1. [n-Bu2(F)SnOSn(F)n-Bu2]2 (3a)
Sn(1)ꢀ ꢀ ꢀCl(1) separation is 3.663(2) A [52].
White solid (1.95 g, 75%, m.p. 180ꢁ
/
185 8C (Lit. m.p.
0.91ꢁ0.97 (m, 24H),
1.73 (m, 16H). 13C-NMR:
117/19Sn)ꢀ
591/618 Hz), 24.0
567/594 Hz), 26.7, 26.8. 19F-NMR:
132.4 (1J(19FÃ117/119Sn)ꢀ741 Hz, 1J(19FÃ
117/119Sn)ꢀ1763 Hz). 119Sn-NMR: dꢀ
142.2 (t,
1J(119SnÃ19F)ꢀ 159.4 (t, 1J(119SnÃ19F)ꢀ
771 Hz), ꢂ
1
115ꢁ
1.35ꢁ
dꢀ
13.5, 23.1 (1J(13CÃ
(1J(13CÃ117/19Sn)ꢀ
dꢀ
/
117 8C) [4]). H-NMR: dꢀ
/
/
/
1.51 (m, 32H), 1.63ꢁ
/
/
/
/
3. Experimental
/
/
/
ꢂ
/
/
/
/
/
/
ꢂ
/
/
/
/
/
/
3.1. General methods
1795 Hz). Anal. Calc. for C32H72F4O2Sn4 (1039.7): C,
37.0; H, 7.0. Found: C, 37.4; H, 7.6%.
The diorganotin oxides (n-Bu2SnO)n and (n-Oct2-
SnO)n were commercially available (Aldrich, Ventron),
whereas (Me2SnO)n, (Et2SnO)n, (i-Pr2SnO)n, (c-Hex2-
SnO)n and (Ph2SnO)n were prepared according to
literature procedures [41]. 119Sn-NMR (100.74 MHz)
and 19F-NMR (254.19 MHz) spectra were recorded
using a JEOL-GX 270 MHz FT-NMR spectrometer
and are referenced to Me4Sn and CFCl3, respectively.
1H-NMR (299.98 MHz) and 13C-NMR (75.44 MHz)
were obtained on a Varian 300 MHz Unity Plus NMR
spectrometer, and are referenced to Me4Si. All chemical
shifts were recorded in CDCl3, unless otherwise indi-
cated. 119Sn-MAS-NMR spectra were recorded using a
JEOL Eclipse Plus 400 MHz FT-NMR spectrometer,
referenced to Me4Sn. Uncorrected melting points (m.p.)
were determined on a Reichert hot stage. Microanalyses
were performed at the Australia National University
(Canberra, Australia) or by CMAS Belmont (Geelong,
Australia).
For (n-Oct2SnO)n ꢁNH4F a complex mixture was
/
obtained (2.50 g). No pure product could be isolated
(see text).
3.2.2. [c-Hex2(F)SnOSn(F)c-Hex2]2 (5a)
Colourless solid (2.68 g, 86%, m.p. (dec.)ꢀ
1H-NMR: dꢀ 2.50 (m). 13C-NMR: dꢀ
1.20ꢁ 26.8, 28.8,
28.9, 30.2, 30.4, 42.0, 42.2. 19F-NMR: dꢀ
144.9
117/119Snendo)ꢀ
822
1875/1956 Hz). 119Sn-NMR:
19F)ꢀ
1950 Hz), ꢂ212.0 (t,
19F) 778 Hz). Anal. Calc. for C48H88F4O2Sn4
(1248.0): C, 46.2; H, 7.1. Found: C, 46.3; H, 7.2%.
For (i-Pr2SnO)n ꢁNH4F a complex mixture was
obtained (1.80 g). No pure product could be isolated
(see text). For (Ph2SnO)n ꢁNH4F a complex mixture was
/
295 8C).
/
/
/
/
ꢂ
/
1
(1J(19FÃ
/
117/119Snendo)ꢀ
Hz, J(19FÃ117/119Snexo)ꢀ
dꢀ
237.6 (t, 1J(119SnÃ
1J(119SnÃ
/
723, J(19FÃ
/
/
1
/
/
/
ꢂ
/
/
/
/
/
/
/
obtained (0.58 g). No pure product could be isolated
(see text).

J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ
/83
81
3.2.3. [Me2(Cl)SnOSn(Cl)Me2]2 (8a)
White solid (1.58 g, 82%, m p.ꢀ280 8C (Lit. m.p.ꢀ
300 8C) [4]). 119Sn-NMR: dꢀ
62.6, ꢂ114.4.
3.2.10. [n-Oct2(Br)SnOSn(Br)n-Oct2]2 (18a)
Colourless solid (3.90 g, 90%, m.p. 64 8C). 1H-NMR:
dꢀ0.87 (broad s, 12H), 1.29 (broad s, 34H), 1.86 (broad
s, 4H), 1.90 (broad s, 18H). 13C-NMR: dꢀ
14.1, 14.1,
22.6, 22.7, 25.1, 25.6, 29.1, 29.2, 29.3, 31.8, 31.9, 33.3,
33.5, 36.4, 33.5. 119Sn-NMR: dꢀ 82.0 (2J(117SnÃ
OÃ 79 Hz), ꢂ OÃ 79
119Sn)ꢀ 130.1 (2J(117Snà 119Sn)ꢀ
Hz). 119Sn-MAS-NMR: dꢀ
74.0, ꢂ134.0. Anal.
/
/
/
ꢂ
/
/
/
/
3.2.4. [Et2(Cl)SnOSn(Cl)Et2]2 (9a)
White solid (1.32 g, 60%, m.p. 168ꢁ
175.5ꢁ
176.5 8C) [4]). 119Sn-NMR: dꢀ
/
ꢂ
/
/
/
170 8C (Lit. m.p.
/
/
/
/
/
/
/
/
ꢂ
/
89.1, ꢂ137.6.
/
/
ꢂ
/
/
Calc. for C64H136Br4O2Sn4 (1732.2): C, 44.4; H, 7.9.
Found: C, 44.3; H, 8.1%.
3.2.5. [n-Bu2(Cl)SnOSn(Cl)n-Bu2]2 (10a)
White solid (2.65 g, 96%, m.p. 110ꢁ111 8C (Lit. m.p.
112ꢁ
114 8C) [4]). 119Sn-NMR: dꢀ 91.4 (2J(117SnÃ
OÃ 74 Hz), ꢂ OÃ 71
119Sn)ꢀ 140.3 (2J(117Snà 119Sn)ꢀ
Hz).
/
/
/
ꢂ
/
/
3.2.11. [i-Pr2(Br)SnOSn(Br)i-Pr2]2 (20a)
/
/
/
/
/
/
Colourless solid (2.34 g, 80%, m.p. (dec.)ꢀ
1H-NMR: dꢀ
1.24ꢁ1.73 (m, 48H), 2.20ꢁ2.54 (m, 8H).
13C-NMR: dꢀ20.1, 21.5 (2J(13CÃ117/19Sn)ꢀ
18 Hz),
40.5. 119Sn-NMR: dꢀ 91.9 (2J(117Snà 119Sn)ꢀ
OÃ 98
Hz), ꢂ OÃ
144.0 (2J(117Snà 119Sn)ꢀ98 Hz). 119Sn-MAS-
NMR: dꢀ 72.0, 148.0. Anal. Calc. for
/
270 8C).
/
/
/
/
/
/
3.2.6. [n-Oct2(Cl)SnOSn(Cl)n-Oct2]2 (11a)
White solid (3.58 g, 92%, m.p. 95 8C). 1H-NMR: dꢀ
0.88 (broad s, 12H), 1.29 (broad s, 34H), 1.78 (broad s,
4H), 1.81 (broad s, 18H). 13C-NMR: dꢀ
14.0, 14.0,
22.6, 22.6, 25.0, 25.2, 29.1, 29.2, 29.2, 31.8, 31.9, 33.1,
33.2, 33.5, 33.6. 119Sn-NMR: dꢀ 90.8 (2J(117SnÃ
OÃ 69 Hz), ꢂ OÃ 71
119Sn)ꢀ 138.2 (2J(117Snà 119Sn)ꢀ
Hz). 119Sn-MAS-NMR: dꢀ
84.0, ꢂ141.0. Anal.
/
ꢂ
/
/
/
/
/
/
/
/
/
/
ꢂ
/
ꢂ
/
/
C24H56Br4O2Sn4 (1171.1): C, 24.6; H; 4.8. Found: C,
24.7; H, 4.8%.
/
ꢂ
/
/
/
/
/
/
/
/
3.2.12. [Me2(AcO)SnOSn(OAc)Me2]2 (29a)
/
ꢂ
/
/
Colourless solid (1.64 g, 76%, m.p. 206ꢁ
/
210 8C (Lit.
0.64ꢁ0.92 (m,
13C-NMR:
dꢀ5.92
Hz), 8.72
(1J(13CÃ
766/800 Hz), 22.9 (Me), 177.5 (CÄ
O). 119Sn-
NMR: dꢀ OÃ 103 Hz),
171.4 (2J(117Snà 119Sn)ꢀ
184.6 (2J(117Snà 119Sn)ꢀ
OÃ 101 Hz). Anal. Calc. for
Calc. for C64H136Cl4O2Sn4 (1554.4): C, 49.5; H, 8.8.
Found: C, 48.5; H, 9.0%.
1
m.p. 115ꢁ
24H), 1.95
(1J(13CÃ117/19Sn)ꢀ
117/19Sn)ꢀ
/
117 8C) [49]). H-NMR: dꢀ
(s, 12H).
715/750
/
/
/
/
/
/
3.2.7. [c-Hex2(Cl)SnOSn(Cl)c-Hex2]2 (12a)
/
/
Colourless solid (2.76 g, 84%). M p.(dec.)ꢀ
1H-NMR: dꢀ 2.50 (m). 13C-NMR: dꢀ
1.20ꢁ 26.2, 26.7,
26.8, 28.3, 29.0, 29.9, 30.5, 31.3. 119Sn-NMR: dꢀ
139.0, ꢂ OÃ 89 Hz). Anal.
202.7 (2J(117Snà 119Sn)ꢀ
/
250 8C.
/
ꢂ
/
/
/
/
/
/
/
ꢂ
/
/
/
/
/
ꢂ
/
C16H36O10Sn4 (863.2): C, 22.3; H, 4.2. Found: C, 22.6;
H, 4.1%.
/
/
/
/
Calc. for C48H88Cl4O2Sn4 (1313.9): C, 43.9; H, 6.8.
Found: C, 43.0; H, 6.5%.
3.2.13. n-Oct2Sn(OAc)2 (32b)
Colourless oil (3.71 g, 80%). 1H-NMR: dꢀ
/
0.88
(broad s, 6H), 1.29 (broad s, 28H), 1.67 (broad s, 6H).
13C-NMR: dꢀ
13.9, 22.5, 24.3, 25.0, 25.5, 29.0, 31.7,
33.1, 181.4 (CÄ 148.1.
O). 119Sn-NMR: dꢀ
3.2.8. [Et2(Br)SnOSn(Br)Et2]2 (16a)
White solid (1.59 g, 60%, m.p. 178 8C (Lit. m.p. 172ꢁ
/
/
1
173 8C) [3]). H-NMR: dꢀ
1.97 (t, 16H). 13C-NMR: dꢀ
(1J(13CÃ117/19Sn)ꢀ
535/561 Hz),
117/19Sn)ꢀ586/612 Hz). 119Sn-NMR: dꢀ
(2J(117Snà 119Sn)ꢀ 128.9 (2J(117SnÃ
OÃ 79 Hz),
OÃ 79 Hz). Anal. Calc. for C16H40Br4O2Sn4
119Sn)ꢀ
/
1.41ꢁ
/
1.52 (m, 24H), 1.86ꢁ
9.55, 10.4, 27.8
29.4
(1J(13CÃ
79.3
/
/
/
ꢂ
/
/
/
/
/
3.2.14. c-Hex2Sn(OAc)2(H2O) (33b)
Colourless solid (1.27 g, 91%, m.p. 50ꢁ
NMR: dꢀ0.80ꢁ
1.99 (m, 22H), 2.10 (s, 6H). 13C-NMR:
dꢀ 12 Hz), 28.4
20.5 (Me), 26.3 (4J(13CÃ117/19Sn)ꢀ
(3J(13CÃ117/119Sn)ꢀ100/104 Hz), 29.6 (2J(13CÃ
117/119Sn)ꢀ23 Hz), 42.8 (1J(13CÃ117/19Sn)ꢀ
517/540
Hz), 181.4 (CÄ
O). 119Sn-NMR: dꢀ 215.3. 119Sn-
1
/
/
ꢂ
/
/
54 8C). H-
/
/
/
ꢂ
/
/
/
/
/
/
/
/
/
(1058.9): C, 18.2; H, 3.8. Found: C, 18.5; H, 3.7%.
/
/
/
/
/
/
3.2.9. [n-Bu2(Br)SnOSn(Br)n-Bu2]2 (17a)
/
/
ꢂ
/
White solid (3.05 g, 95%, m.p. 104 8C (Lit. m.p. 107ꢁ
/
MAS-NMR: dꢀ
/
ꢂ401.8. (discussed in text) IR (KBr)
/
1
108 8C) [3]). H-NMR: dꢀ
1.57 (m, 16H), 1.70ꢁ
2.10 (m, 32H). 13C-NMR: dꢀ
13.5, 26.2, 26.4, 27.1 (3J(13CÃ117/19Sn)ꢀ
33 Hz), 27.7
(3J(13CÃ117/19Sn)ꢀ30 Hz), 36.0 (1J(13CÃ117/19Sn)ꢀ
522/547 Hz), 36.2 (1J(13CÃ117/19Sn)ꢀ
570/594 Hz).
119Sn-NMR: dꢀ 81.3 (2J(117Snà 119Sn)ꢀ
OÃ 79 Hz),
129.8 (2J(117Snà 119Sn)ꢀ79 Hz). 119Sn-MAS-
OÃ
NMR: dꢀ 58.4, 136.4. Anal. Calc. for
/
0.93ꢁ
/
0.99 (m, 24H), 1.36ꢁ
/
n(H2O): 3394.7 cmꢂ1. Anal. Calc. for C16H30O5Sn
(421.1): C, 45.6; H, 7.2. Found: C, 45.7; H, 7.3%.
/
/
13.5,
/
/
/
/
/
/
3.3. Synthesis of [c-Hex2(F)SnOSn(Cl)c-Hex2]2 (36)
/
/
/
ꢂ
/
/
/
/
A solution of 5a (0.11 g, 0.09 mmol) in toluene (2.0
ml) was added to a solution of 12a (0.12 g, 0.09 mmol) in
toluene (2.0 ml) and the mixture was heated at 100 8C
for 12 h. The solvent was removed in vacuo and the
ꢂ
/
/
/
/
/
ꢂ
/
ꢂ
/
C32H72Br4O2Sn4 (1283.4): C, 30.0; H, 5.7. Found: C,
30.5; H, 5.9%.
resulting residue was recrystallised from chloroformꢁ
/

82
J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ83
/
hexane to afford 36 as colourless crystals (0.111 g, 95%).
M.p. (dec.)ꢀ 1.20ꢁ2.50 (m).
230 8C. 1H-NMR: dꢀ
13C-NMR: dꢀ
26.8, 26.9, 28.9, 29.1, 30.7, 30.9, 43.9
(2J(13CÃ19F)ꢀ6 Hz), 44.3 (2J(13CÃ19F)ꢀ11 Hz). 19F-
NMR: dꢀ 1220 Hz,
124.1 (1J(19FÃ117/119Sn)ꢀ
1J(19FÃ117/119Sn)ꢀ
1489 Hz) and minor signals (see
text). 119Sn-NMR: dꢀ 175.3 (d, 1J(119SnÃ19F)ꢀ
1240 Hz, 2J(119Snà 117Sn)ꢀ
OÃ 220 Hz), ꢂ226.1 (dd,
1J(119SnÃ19F)ꢀ1540 Hz, J(119Snà 117/119Sn)ꢀ
OÃ 212/
217 Hz, 3J(119Snà 19F)ꢀ
OÃSnà 32 Hz) and minor
signals (see text). 119Sn-MAS-NMR dꢀ
183.0 (4Sn,
226.0 (2Sn, d,
234.0 (2Sn, d,
least-squares procedure based on F2 [56]. All non-H
atoms were generally refined with anisotropic displace-
ment parameters (with some exceptions as discussed
below) and H atoms were included in the models in their
calculated positions in the riding model approximation.
The refinements converged after the inclusion of a
/
/
/
/
/
/
/
/
/
ꢂ
/
/
/
/
/
1/[s2(F2o)ꢃaP2ꢃ
/
/
bP]
(F2oꢃ2F2c)/3. The structure of 29a was found
/
ꢂ
/
/
/
weighting scheme of the form wꢀ
/
/
/
/
/
where Pꢀ
/
/
2
/
/
/
/
/
to crystallise in the non-centrosymmetric space group
Pna21. Final refinement confirmed the choice of space
group as the centrosymmetric mate, Pnma, would
require the molecule to possess a mirror plane or be
disposed about a centre of inversion. However, the
overall structure is close to centrosymmetric and some
difficulties were noted in the refinement. In particular,
/
/
/
/
/
ꢂ
/
d, 1J(119SnÃ
1J(119SnÃ19F)ꢀ
1J(119SnÃ19F)ꢀ
/
19F)ꢀ
/
1150 Hz),
ꢂ
/
/
/
1550
Hz),
ꢂ
/
/
/
1630 Hz).
Anal. Calc. for C48H88Cl2F2O2Sn4 (1281.0): C, 45.0;
H, 6.9. Found: C, 45.9; H, 7.4%.
the C(12) atom was modelled isotropically. Further, a
ꢂ3
˚
rather large residual electron density peak of 2.46 e A
was located in a chemically non-sensible position. The
absolute structure was determined on the basis of the
3.4. Crystallography
value of Flack parameter [57] of 0.15(9). The C(8)Ã
/
Intensity data for colourless crystals of 5a, 20a and
29a were measured at 173 K on a Rigaku AFC7R
C(12) atoms of a cyclohexyl ring in 5a were found to
be disordered over two positions. The two conforma-
tions were assigned equal weight based on the refine-
ment. Similarly, disorder was resolved for the C(46) and
C(48) atoms of a cyclohexyl group in 36. These were
assigned site occupancies of 0.55:0.45 from the refine-
ment. The relatively large residual electron density peak
diffractometer fitted with Moꢁ
the v ꢁ2u scan technique in each case. Data for 36 were
measured at 223 K on a Bruker AXS SMART CCD
diffractometer using MoꢁKa radiation and v-scans.
/
Ka radiation employing
/
/
Data were corrected for Lorentz and polarisation effects
and for absorption using empirical procedures [53,54].
Crystallographic data and refinement details are sum-
marised in Table 4. The structures were solved using
heavy-atom methods [55] and refined by a full-matrix
˚
in 36 is located 0.86 A from the Sn(1) atom. Final
refinement details are given in Table 4 and the crystal-
lographic numbering schemes are shown in Figs. 2ꢁ5
/
Table 4
Crystallographic data and refinement details for compounds 29a, 20a, 5a and 36
29a
20a
5a
36
Formula
C
863.2
16H36O10Sn4
C24H56Br4O2Sn4
1171.1
Monoclinic
P21/n
C50H90Cl6F4O2Sn4
1486.7
Monoclinic
C2/c
C48H88Cl2F2O2Sn4
1280.8
Triclinic
Formula weight
Crystal system
Space group
Orthorhombic
Pna21
16.261(3)
7.706(4)
21.583(5)
90
¯
P
/1/
˚
a (A)
9.396(5)
18.339(8)
11.127(9)
90
23.091(4)
14.263(4)
20.086(5)
90
11.9959(6)
12.1875(6)
19.4730(9)
74.018(1)
88.875(1)
76.026(1)
2652.6(2)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
90
90
98.72(1)
90
112.93(1)
90
3
˚
V (A )
Z
2704(1)
4
2.120
1895(2)
2
2.052
6093(2)
4
1.621
Dcalc (cmꢂ3
)
1.604
20.03
1288
m (cmꢂ1
F(000)
)
36.93
1648
68.53
1112
19.30
2976
Crystal size (mm)
Unique data
Data with I ]2s(I)
R(F2) for observed data
wR(F2) for all data
a
0.16ꢄ0.24ꢄ0.32
3243
2831
0.11ꢄ0.16ꢄ0.32
4346
2747
0.32ꢄ0.32ꢄ0.40
7000
4468
0.04ꢄ0.07ꢄ0.16
15 106
9534
0.034
0.114
0.028
0.076
0.039
0.154
0.055
0.146
0.0682
0.0545
19.3613
2.46
0.0111
1.3859
0.62
0.0789
33.3785
0.92
b
0
1.62
ꢂ3
˚
r (e A
)

J. Beckmann et al. / Journal of Organometallic Chemistry 659 (2002) 73ꢁ
/83
83
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