push-push and push-pull polystannanes

Article abstract of DOI:10.1039/c8dt03043j

The synthesis and characterization of polystannanes with push or pull moieties attached to the tin backbone are described. Precursor tetra aryl- (1, 2) stannanes were converted to mono- (3) and dichloro- (4, 5) stannanes by either sequential chlorination or by redistribution reactions with SnCl₄. Compounds 4 and 5 were transformed to polymerisable tin dihydride monomers 6 and 7 using a large excess (10×) of NaBH₄. Homopolymer 8 with electron donating aryl substituents (p-MeOC₆H₄-) was synthesized by dehydrogenative polymerization using Wilkinson's catalyst. Attempts to prepare the homopolymer 9 with electron withdrawing aryl substituents (p-CF₃C₆H₄-) from the dehydrocoupling of 7 using similar conditions led only to the formation of low molecular weight oligomeric species. Two alternating polymers, 10 and 11, were synthesized by condensation polymerization of (n-Bu)₂Sn(NEt₂)₂ with monomers 6 or 7. The first was a push-push alternating polymer, 10, comprised of a repeating unit consisting of two different electron donating groups (p-MeOC₆H₄-, n-Bu) at neighboring tin centres. The second was a push-pull alternating polymer, 11, bearing both an electron donating group (n-Bu) and a strongly electron withdrawing substituent (p-CF₃C₆H₄-) at neighboring tin atoms. All small molecule stannanes and tin-containing polymers were characterized by NMR (¹H, ¹³C, ¹¹⁹Sn, and where required ¹⁹F) spectroscopy, MS or EA. The absolute molecular weights of tin polymers (8, 10, 11) were determined by triple detection GPC and in the range of 1.07 × 10⁴ to 1.95 × 10⁴ Da. Rapid photodegradation of polymers was observed by UV-Vis spectroscopy, with a slower degradation observed for the push-pull polymer, 11, compared to the push-push polymer, 10.

Full text of DOI:10.1039/c8dt03043j

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ARTICLE
“Push-Push and Push-Pull” Polystannanes
J. S. Dhindsa,a B. F. Jacobs,a A. J. Lough,b and D. A. Foucher*a
Received 00th January 20xx,
Accepted 00th January 20xx
The synthesis and characterization of polystannanes with "push" or "pull" moieties attached to the tin backbone are
described. Precursor tetra aryl- (1, 2) stannanes were converted to mono- (3) and dichloro- (4, 5) stannanes by either
sequential chlorination or by redistribution reactions with SnCl4. Compounds 4 and 5 were transformed to polymerisable
tin dihydride monomers 6 and 7 using a large excess (10 x) of NaBH4. Homopolymer 8 with electron donating aryl
substituents (p-MeOC6H4-) was synthesized by dehydrogenative polymerization using Wilkinson’s catalyst. Attempts to
prepare the homopolymer 9 with electron withdrawing aryl substituents (p-CF3C6H4-) from the dehydrocoupling of 7 using
similar conditions led only to the formation of low molecular weight oligomeric species. Two alternating polymers, 10 and
11, were synthesized by condensation polymerization of (n-Bu)2Sn(NEt2)2 with monomers 6 or 7. The first was a “push-
push” alternating polymer, 10, comprised of a repeating unit consisting of two different electron donating groups (p-
MeOC6H4-, n-Bu) at neighboring tin centres. The second was a “push-pull” alternating polymer, 11, bearing both an
electron donating group (n-Bu) and a strongly electron withdrawing substituent (p-CF3C6H4-) at neighboring tin atoms. All
small molecule stannanes and tin-containing polymers were characterized by NMR (1H, 13C, 119Sn, and where required 19F)
spectroscopy, MS or EA. The absolute molecular weight of tin polymers (8, 10, 11) were determined by triple detection
GPC and in the range of 1.07 × 104 to 1.95 × 104 Da. Rapid photodegradation of polymers was observed by UV-Vis
spectroscopy, with a slower degradation observed for the “push-pull” polymer, 11, compared to the “push-push” polymer,
10.
DOI: 10.1039/x0xx00000x
www.rsc.org/
degrade to oligomeric stannanes, cyclic stannanes or
stannoxanes.
Introduction
We have recently detailed the stoichiometric condensation
Organic conducting polymers including polythiophenes and
poly (p-phenylenevinylene) continue to draw extensive
research interest due to their relative stabilities, low cost and
processability for a variety of electronic applications including
thin film transistors,1 photovoltaics,2 polymeric wires,3
sensors,4 and other devices.5 Less explored are main group
containing inorganic polymers, including homopolymers of Ge
of high purity dialkyl- or diaryl- tin dihydrides and dialkyl- tin
diamides in non-polar solvents as new route to
a
polystannanes (Scheme 1).24 Herein we describe the step-
growth approach to preparing alternating polystannanes with
distinct alternating diaryl and dialkyl push/pull substituents
attached to the tin backbone.
and Sn.
Polystannanes are semi-conductive polymers
consisting of a backbone of covalently bonded tin atoms.6 They
possess interesting chemical, thermal, optical and electronic
properties as a result of the delocalization of
their backbones.6,7
σ-electrons along
Specialized chain growth syntheses have been employed to
obtain polystannanes including Wurtz,8–14 electrochemical,15
and
dehydrogenative
coupling.10,16–23
Thermally,
polystannanes are quite stable (up to 200 C) under nitrogen
atmosphere as well as in air,12 but show extreme sensitivity
towards light and moisture exposure where they rapidly
°
Results and discussion
Synthesis of tin monomers 6 and 7
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Tetraarylstannanes
1
and
2
were previously synthesized by The 119Sn NMR spectra of
1
to
7
(Table 1) reveal significant
Wharf et al.25 and King et al.26 by Grignard reactions of a downfield resonances for the mono- (
3
) or dichlorinated (
) stannanes compared to their parent tetraarylstannanes
and Upfield resonances for the tin dihydrides and
(Table 1) was observed, which is typical for other reported
4
bromobenzenes with SnCl4. In this study,
prepared via lithium-halogen exchange13 of the aryl bromide
with n-BuLi, followed by the reaction with SnCl4 to obtain
and in 77 % and 94 % yields, respectively. Compounds and diarylstannanes. H NMR shifts of the aromatic protons of the
(Scheme 2) were isolated in 86 % and 51 % yields from chlorinated tin compounds and were also
characteristically deshielded from their parent tetraaryltin
compounds ( and ). The aromatic protons ( and ) in are
chemically distinct, but are magnetically equivalent (Table 1).
The hydride protons in and
display strong 119/117Sn-H
couplings ( : J119Sn-H = 954 Hz, J117Sn-H = 912 Hz; : J119Sn-H = 1012
1 and 2 were readily and 5
(
1
2
)
.
6
7
1
1
2
3
4
(
3
,
4
5)
1
2
α
β
2
6
7
6
7
Hz, J117Sn-H = 963 Hz).
Table 1. 119Sn, 1H NMR spectroscopic data for compounds 1 to 7
α
β
sequential 2h exchange reactions with 1.0 M HCl (1:1 ratio) in
under 2 h. A similar stepwise exchange reaction with HCl was
Sn
R
also attempted with CF3- containing tetrastannane
resulted in only the recovery of the starting material. Dichloro-
stannane was successfully synthesized in a 61 % yield as
previously demonstrated,13 via a more traditional and longer
2, which
119Sn NMR δ (ppm)
1H NMR δ (ppm)
(α, β)
Compounds
5
1*
−116.2
−130.9
−27.5
6.96, 7.50
7.69
redistribution reaction of
2
with SnCl4 under static vacuum for
2*
5 days at 180 °C.
3*
7.02, 7.59
7.06, 7.63
7.83, 7.84
6.81, 7.40
7.13, 7.32
4*
−14.5
5*
6**
−32.6
−229.5
−235.5
7**
* = CDCl3; ** = C6D6
o
20 C afforded
Recrystallization of
4
with CH2Cl2/hexanes at
−
small white crystals which were appropriate for single-crystal
X-ray diffraction (Figure 1). The bond length and angles
observed for 4 are similar to other tin diaryl dichlorides
reported in literature.13
R
R
Scheme 3.
scheme for
dihydride
Reaction
synthesis of
aryltin
compounds;
4
,
6
:
R =
−
OMe, and
5, 7: −CF3.
10 eqv. NaBH4
EtOH, 0°C, 1 h
H
Sn H
Cl Sn Cl
Tin
R
R
4, 5
6, 7
dichlorides (
4
and
5) were reacted with a large excess of NaBH4
(10
×
) in EtOH for 1 h to obtain
6
and 7 in 77 % and 97 % yields
respectively (Scheme 3). These dihydrides were observed to be
extremely sensitive to heat and moisture, and therefore
polymerization attempts were carried out on the same day.
Figure 1. ORTEP structure of 4. Selected bond lengths [Å] and angles [°]: Sn(1)-C(1)
2.104(6), Sn(1)-C(8) 2.107(6), Sn(1)-Cl(1) 2.3694(16), Sn(1)-Cl(2) 2.3532(16), C(1)-
Sn(1)-C(8) 127.1(2), C(1)-Sn(1)-Cl(1) 105.73(18), C(1)-Sn(1)-Cl(2) 106.65(18), C(8)-
Sn(1)-Cl(2) 107.08(18), C(8)-Sn(1)-Cl(1) 107.73(18), Cl(2)-Sn(1)-Cl(1) 99.13(6).
Characterization of monomers
2 | J. Name., 2012, 00, 1-3
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Polystannanes 8 and 9
We previously described a condensation polymerization route
which led to the first example of an alternating polystannane,
Previous research by Caseri et al.27 reported that high
molecular weight diaryl polymers could not be prepared by
dehydrogenative coupling using Wilkinson’s catalyst. In the
attempted dehydrocoupling of Ph2SnH2 with Wilkinson’s
12 24
This condensation route involves the polymerization of
.
1:1 ratio of dihydride monomer with (n-Bu)2Sn(NEt2)2 in Et2O
which
catalyst, a poor yield of oligomeric −[Sn(Ph)2)]n−
(Mw < 5 × 104
produces a volatile HNEt2 byproduct (Scheme 5). Polymers, 10
and 11 were recovered as yellow coloured solids. By design,
Da) was obtained when the reaction was performed at 70 oC.27
By contrast, asymmetric dihydrides with alkyl and aryl
substituents have been shown to readily polymerize at RT with
Wilkinson’s catalyst.27 Interestingly, homopolymer,
readily synthesized by dehydrocoupling of using the
Wilkinson’s catalyst in toluene at R.T. to yield an orange
coloured waxy product (Scheme 4). Polymer was purified by
dissolving the crude in minimum amount of THF (~ 10 mL) and
recovery by precipitation from a 6 excess of cold hexanes at
20 C and recovered as an orange powder in 83 % yield. A
8, was
6
8
×
o
−
GPC analysis indicated that a moderate molecular weight
polymer (Mw = 1.07 x 104 Da) was obtained (Table 2). The 119Sn
polymer 10 was constructed as
a “push-push” system
comprising two different electron donating groups (p-
MeOC6H4 and n-Bu) at neighboring tin atoms. Polymer 11 was
synthesized with an electron donating group (n-Bu) and a
strongly electron withdrawing substituent (p-CF3C6H4) at
neighboring tin atoms to make it a “push-pull” system.
NMR spectra of
at -229.6 ppm, with extensive 119Sn and 117Sn couplings
present. Polymer
was previously synthesized13 via a Wurtz
coupling using Na, but was found to be extremely light
sensitive. An attempted dehydrocoupling of using
resulted in recovery of only
8 shows a surprisingly well resolved resonance
9
7
RhCl(PPh3)3 to synthesize
oligomeric material.
9
According to Caseri et al.,27 attaching two phenyl groups
onto one tin impairs the efficiency of Wilkinson’s catalyst
presumably due to steric considerations. Additionally, the
efficiency of the Wilkinson’s catalyst may be dependent on the
Lewis nature of the tin monomer. In our case, the highly
Scheme 5. Reaction scheme for the synthesis of alternating polystannanes; 10: R
= −OMe, 11: R = −CF3 and 12: R = −H.24
electron donating groups (−OMe) of 8 increase the Lewis
basicity of the tin metal center, thereby increasing its
reactivity. By contrast, Wilkinson’s catalyst is presumed to be
less effective for highly electron withdrawing groups such as
The 1H NMR spectrum of 11 shows a broad doublet in aromatic
(−CF3) which render the tin centers more Lewis acidic.
region between
H4 (Figure 2). It also shows a plethora of peaks corresponding
to n-butyl chain between = 0.69 1.59 ppm (H6 H9).
Despite extensive efforts to dry the polymer, trace n-hexanes
was detected in the alkyl region of the 1H NMR spectra of 11
δ = 7.35 − 7.45 ppm corresponding to H3 and
δ
−
−
.
Polystannanes are extremely sensitive to light and moisture
and thermodynamically favour the formation of low molecular
weight oligomers and cyclic oligomers. Purification of these
sensitive polystannanes is tedious, and this polymerization was
conducted several times in attempts to optimize methods of
purification. In earlier attempts, 10 was purified by dissolving
the crude in a minimum amount of dry THF (~10 mL) and
precipitation in a 6
× excess of cold hexanes at −20 °C. This
Therefore, the electronics of the moieties of the tin monomers
likely impacts the degree of polymerization.
purification method was repeated 4 – 5 times in attempts to
obtain clean 119Sn and 1H NMR spectrum. Unfortunately,
repeated purification led to further degradation of the
polymer despite using dry solvents and taking precautions to
avoid ambient light. Therefore, a different and more effective
Alternating polystannanes, 10, 11 and 12
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J. Name., 2013, 00, 1-3 | 3
Scheme 4. Reaction scheme for the synthesis of 8 and 9 via dehydrocoupling of 6
(R = −OMe) and 7 (R = −CF3).

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method of purification was needed. Crude 10 was dissolved in
Journal Name
a minimum amount of toluene (~10 mL) and layered with 6
excess of hexanes. The flask was then slowly cooled to 50
×
UV-Vis spectroscopy and Polymer stability
UV-Vis spectroscopy of 10, and 11 in C6H6 was performed.
The absorption characteristics of all polymers were similar.
Five consecutive scans of homopolymer, revealed no
evidence of degradation in solution or photoscission upon
exposure to light in solution (SI B1A). In contrast to
−
°
C
8,
to precipitate out 10. Solvents were then decanted via cannula
to recover 10 with the removal of majority of the oligomer
species. The 119Sn NMR spectrum of 10 shows two main
8
polymer peaks at
δ = −188.8 ((n-Bu)2Sn) and −208.6
8,
((MeOC6H4)2Sn) ppm indicative of the formation of an
alternating polymer (Supplementary Figure A26, Table 2).
These resonances are downfield from their respective
alternating polymers, 10 (SI B1B) and 11, showed rapid
degradation after five consecutive scans. Complete
(δ 8 (δ = -
= -190.1 ppm)20 and
disappearance of
σ-σ* absorption of 11 was observed in 90
homopolymers, ((n-Bu)2Sn)n
229.6 ppm) in the same solvent (C6D6). The 119Sn NMR
spectrum of 11 shows two polymer peaks at 180.7 ((n-
Bu)2Sn) and 213.9 ((CF3C6H4)2Sn) ppm characteristic of the
minutes (Figure 4). A loss of the characteristic yellow colour
upon purification was visually observed to be faster for the
“push-push” alternating polymer, 10, compared to “push-pull”
alternating polymer, 11. This may indicate that 11 possesses
marginally better light stability as a result of incorporating the
alternating electron donating and electron withdrawing
moieties along the tin backbone. Whereas in alternating
polymer, 10, the electron density is focused onto the tin
backbone, making it more susceptible to photolytic cleavage.
δ
= −
−
formation of an alternating polymer (Supplementary Figure
A30, Table 2). In the case of 11, the (n-Bu)2Sn) half is found 10
ppm further downfield from the homopolymer, ((n-Bu)2Sn)n,
whereas the fluoro-containing half is found 163 ppm further
upfield from
9
. The resonances for 10 and 11 are similar to the
values for other alternating
previously reported
polystannanes.24 Additionally, a number of small tin impurities
were also detected in the 119Sn NMR spectra of 10 and 11
which were not assigned. As a result of the extreme light and
moisture sensitivity of polymers 10 and 11, reliable elemental
analysis could not be obtained despite repeated attempts.
Interestingly, homopolymer
8 showed the lowest loss in colour
after UV exposure, indicating that bulky aromatic moieties17
are likely required for the improved stability of the
polystannanes.
Table 2. Characterization data for 8, 9, 10, 11 and 12.
Polymer
119Sn NMR
ppm (C6D6)
−229.6
PDI
Mw (Da) × 104
8
1.07
292
1.07
4.40
2.08
2.95
2.86
9*13
10
−56.7
1.95
1.17
1.88
−189, −209
−181, −214
−187, −208
11
1224
* = Previously synthesized via. Wurtz coupling.
The GPC data for the tin-containing polymers
8,
10 and 11 is
provided in Table 2 and their GPC chromatograms shown in
Figure 3. Alternating polymer, 10 was first prepared by the
dropwise addition of dihydride monomer,
6 to (n-Bu)2Sn(NEt2)2
Figure 4. UV-Vis (C6H6) spectroscopy of polymer 11 showing the degradation.
which resulted in the formation of low molecular weight
oligomeric species (MW: 9.9 × 103 Da). Higher molecular weight Conclusions
10 (Table 2) was observed when polymerization was carried
A series of tetraaryl (
dihydride ( and ) tin small molecules were successfully
synthesized. Homopolymer was synthesized by a catalytic
dehydrogenative coupling reaction of dihydride monomer,
1 and 2), chlorinated (3, 4 and 5) and
out with the rapid addition of dihydride, 6, to (n-Bu)2Sn(NEt2)2.
6
7
8
6.
Alternating polymers, 10, and 11 were successfully prepared
by the condensation polymerization of the dihydride and the
diamide monomers. It was expected that the use of bulky
aromatic moieties onto the tin backbone will improve the light
and moisture stability of the polystannanes. However,
alternating polymers 10 and 11 demonstrated extreme
sensitivity towards the light and moisture, and experienced a
rapid degradation in solution while purification. Despite the
initial promise of improved stability from the incorporation of
the alternating electron donating and the electron
4 | J. Name., 2012, 00, 1-3
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Figure 3. GPC chromatogram of polymers, 8, 10 and 11.

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withdrawing moieties along the tin backbone, further design mL, 30.35 mmol) was added. The solution was cooled to -94 oC
features are needed to achieve complete light and moisture before the addition of a 1.6 M solution of n-BuLi (19.92 mL,
stable polystannanes. We are actively exploring the 31.87 mmol) dropwise and the mixture was allowed to stir for
incorporation of both light absorbing groups28 onto the 2 h at this temperature. The reaction mixture was allowed to
polymer backbone along with hypercoordinate architecture29 warm to R.T. before SnCl4 (0.89 mL, 7.59 mmol) was added
to achieve this goal.
dropwise to the solution. The clear reaction mixture turned
milky white and was allowed to stir for 4 h at R.T., and
subsequent quenched with t-BuOH (~1 mL). The reaction
mixture was filtered using a Schlenk filter funnel and solvent
was removed in vacuo to produce a white coloured solid.
Experimental
Materials and methods
Crude
in cold EtOH (40 mL) at
mp 132
133 oC (lit 133
1 was dissolved in hot toluene (10 mL) and precipitated
All reagents and solvents were obtained from Sigma-Aldrich
and used as received, unless otherwise indicated. Solvents
were dried either through an MBraun solvent drying system,
or through vacuum distillation and stored under an inert
nitrogen atmosphere. All reactions were carried out under
nitrogen atmosphere using Schlenk techniques unless
otherwise noted. Nuclear magnetic resonance (NMR)
spectroscopic experiments were carried out on a Bruker 400
MHz Avance spectrometer using CDCl3 or C6D6 as the solvent.
1H NMR (400 MHz) and 13C NMR (100.6 MHz) spectra were
referenced to the residual proton and central carbon peak of
the solvent. The 19F NMR (376 MHz) and 119Sn NMR (149 MHz)
were referenced to CFCl3 and SnMe4, respectively as internal
−
−
20 oC, resulting in a pure white solid,
1
−
134 oC25). Analysis by 119Sn, H, and
13C NMR agreed with literature values reported by Lehmler et
al.30 Yield 77 % (3.18 g).
1H NMR (400 MHz, CDCl3, δ): 7.50 (d, 8H, J = 8.5 Hz, 3J119Sn-H
= 27 Hz, 3J117Sn-H = 19 Hz), 6.96 (d, 8H, J = 8.5 Hz, 4JSn-H = 9.3 Hz),
3.82 (s, 12H) ppm. 13C {1H} NMR (100 MHz, CDCl3, δ): 160.52,
138.28 (2JC-Sn = 21.5 Hz), 128.81 (1JC-Sn = 264 Hz), 114.48 (3JC-Sn
27.5 Hz), 55.03 ppm. 119Sn NMR (149 MHz, CDCl3, δ):
116.1 ppm.
Tetra(4-benzotrifluoride)stannane (
=
−
2) was prepared by the
previously described synthesis by King et al.26 and Foucher et
al.13 Organolithium route was used instead of Grignard route
due to the higher yield compared to Grignard reaction.
Synthesis of chlorinated arylstannanes
standards. All the chemical shifts are given in
δ (ppm) relative
to the solvent and assigned to atoms. All NMR spectra were
analyzed on MestReNova v6.0.2 software. High-resolution
mass spectrometry was performed using an accuTOF DART-MS
at the University of Toronto. Molecular weights of polymers
were determined by gel permeation chromatography (GPC)
using a Viscotek Triple Model 302 Detector system equipped
Compounds 3 and 4 were prepared according to the method
previously described by Munguia et al.31
Mono-chloro-tri-(4-methoxyphenyl)stannane
(
3
): In
a
100 mL Schlenk flask, compound
1 (2.17 g, 3.97 mmol) was
with
a
Refractive Index Detector (RI),
a
four capillary
) laser light
added and dissolved in C6H6 (~ 50 mL). The solution was then
placed in an ice bath and allowed to cool down for 15 min
before the addition of a solution of 1.0 M HCl in Et2O (3.97 mL,
3.97 mmol) dropwise. The reaction mixture was allowed to stir
differential viscometer (VISC), a right angle (90
°
scattering detector. GPC columns were calibrated versus
polystyrene standards (American Polymer Standards). A flow
rate of 1.0 mL min-1 was used with ACS grade THF as eluent.
at 0
additional 60 min. Next, the solvent was removed in vacuo,
resulting in the formation of a white viscous liquid. Crude
was dissolved in hot DCM (10 mL) and precipitated out from
cold hexanes (40 mL) at -20 C. The top solvent layer was
decanted and removed in vacuo to obtain a viscous white
liquid, Yield 86.0 % (1.62 g).
1H NMR (400 MHz, CDCl3, δ): 7.59 (d, 6H, J = 8.5 Hz), 7.02
(d, 6H J = 8.5 Hz), 3.84 (s, 9H) ppm. 13C {1H} NMR (100 MHz,
CDCl3, δ): 161.40, 137.41, 128.10, 114.92, 55.03 ppm. 119Sn
°C for 30 min before removing the ice bath and stirring for
GPC sample were prepared using
mL THF, and filtered using
10-15 mg of polymers per
0.45 filter. UV-Vis
a
ꢀm
3
spectroscopy was carried out using Cary 5000 UV-Vis-NIR
spectrophotometer by Agilent technologies. Samples were
prepared by dissolving the polymer in benzene. Elemental
analysis of polymers and dichloride compound was performed
by Atlantic Microlab of Norcross Georgia.
°
3.
Note: Elemental analysis of polymers
8 and 10 were
unsuccessful despite repeated attempts (3 ×). This was due to
decomposition of the samples during transport or analysis.
Only low resolution mass spectrometry were successfully
NMR (149 MHz, CDCl3, δ): −27.8 ppm.
carried out on compounds
dehydrogenation that would occur before samples could be
detected, despite taking all necessary precautions. All
6 and 7 due to the rapid
Di-chloro-di-(4-methoxyphenyl)stannane (
4): In a 100 mL
Schlenk flask, compound 3 (1.62 g, 3.41 mmol) was added and
dissolved in C6H6 (~ 25 mL). The solution was then placed in an
ice bath and allowed to cool down for 15 min before the
addition of a solution of 1.0 M HCl in Et2O (3.41 mL, 3.41
mmol) dropwise. The reaction mixture was allowed to stir at 0
polymers and monomers were found to be sufficiently stable
1
to conduct extensive NMR analysis (119Sn, H, and 13C) and 2D
NMR to make all chemical shift assignments (see SI material).
°C for 30 min before removing the ice bath and stirring for
additional 60 min. Next, the solvent was removed in vacuo,
Synthesis of tetraarylstannanes
Tetra(4-methoxyphenyl)stannane (1): In a 250 mL Schlenk flask
resulting in the formation of a pinkish white colour solid. Crude
charged with 100 mL of Et2O, 1-bromo-4-methoxybenzene (3.8
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4
was washed with hexanes (3
× 10 mL) resulted in a formation was extracted in a 250 mL separatory funnel. After extraction,
of a white powder. It was then allowed to recrystallize from the aqueous layer was discarded and the organic layer was
hexanes at
-20 °C, which resulted in the formation of white transferred to a 50 mL Schlenk flask and hexanes removed in
needle like crystals of
4
, mp 74
−
75 oC (lit 75.5
−
76.5 oC32) Yield vacuo, which resulted in the formation of yellow coloured
1
51.1 % (0.71 g).
powder. Analysis by 119Sn, H, 13C NMR showed the presence
1H NMR (400 MHz, CDCl3, δ): 7.63 (d, 4H, J = 8.5 Hz, 3J119Sn-H of pure compound
7. Yield = 96.9 % (0.28 g).
3
= 42 Hz, J117Sn-H = 35 Hz), 7.06 (d, 4H, J = 8.5Hz, JSn-H = 15.5
4
1H NMR (400 MHz, CDCl3, δ): 7.32 (d, 4H, J = 7.3 Hz), 7.13
Hz), 3.85 (s, 6H) ppm. 13C {1H} NMR (100 MHz, CDCl3, δ): (d, 4H, J = 7.3 Hz), 5.93 (s, 2H, J119Sn-H = 1012 Hz, J117Sn-H = 963
162.37, 136.46 (2JC-Sn = 36.8 Hz), 127.63, 115.41 (3JC-Sn = 47 Hz), Hz) ppm. 13C {1H} NMR (100 MHz, CDCl3, δ): 139.60, 137.48
55.31 ppm. 119Sn NMR (149 MHz, CDCl3, δ):
−
Anal. Calc. C,41.64; H, 3.49; Found. C, 41.56; H, 3.73.
14.5 ppm. EA: (2JC-Sn = 21.1 Hz), 131.14 (2JC-F = 32.4 Hz, JC-Sn = 5.9 Hz), 124.79
4
(3JC-F = 3.8 Hz, 3JC-119Sn = 28.8 Hz, 3JC-117Sn = 24.7 Hz), 124.44 (1JC-F
= 272.1 Hz) ppm. 119Sn NMR (149 MHz, CDCl3, δ):
235.5 ppm.
was 19F NMR (CDCl3, δ): 62.8 (s, CF3) ppm. LRMS-DART (m/z): [M+]
−
Di-chloro-di-(4-(trifluoromethyl)phenylstannane
(
5)
−
prepared by the previously described synthesis by Foucher et + H2O. Calc 428.95; Found 428.9.
al.13
Synthesis of Polystannanes
Synthesis of dihydride arylstannanes
Poly-(di-(4-methoxyphenyl)stannane)
(8): In a 50 mL
Di-hydride-di-(4-methoxyphenyl)stannane (
Schlenk flask, compound (0.71 g, 1.74 mmol) was added and (0.034 g, 0.036 mmol) was added and dissolved in 10 mL of dry
dissolved in 8 mL of EtOH and placed into an ice bath. In toluene and stirred for 20 minutes. In a separate 50 mL
another 50 mL Schlenk flask, excess NaBH4 (0.66 g, 17.41 Schlenk flask, compound (0.31 g, 0.91 mmol) was added and
6): In a 100 mL Schlenk flask wrapped with aluminum foil, Wilkinson’s catalyst
4
6
mmol) was added and dissolved in 18 mL of EtOH and placed dissolved in 5 mL of dry toluene. It was then added by syringe
into an ice bath. In a separate 50 mL round bottom, 25 mL to a solution of Wilkinson’s catalyst dropwise and the reaction
distilled water was degassed at 0
prepared. The solution of NaBH4 was added dropwise via solvent was removed in vacuo to produce an orange coloured
cannula to the Schlenk flask containing compound , which waxy product. The crude product was dissolved in 10 mL THF
resulted in the clear white reaction mixture turning yellow. and precipitated out from 60 mL of cold hexanes to obtain an
The reaction mixture was allowed to stir for 45 min at 0 C, orange powder, . Yield = 83.0 % (0.30 g).
°C while the hydride was mixture was allowed to stir at R.T. for 4 h, after which the
4
°
8
after which 30 mL of hexanes were added. Then, 10 mL of
distilled degassed water was added dropwise. The reaction – 6.63 (bm, 4H, H3), 3.28 (s, 6H, H1) ppm. 13C {1H} NMR (100
1H NMR (400 MHz, C6D6, δ): 7.65 – 7.37 (bm, 4H, H4), 7.05
mixture was extracted in a 250 mL separatory funnel. After MHz, C6D6, δ): 160.17 (C2), 139.48 (C4), 133.70 (C5), 114.32
extraction, the aqueous layer was discarded and the organic (C3), 54.04 (C1) ppm. 119Sn NMR (149 MHz, C6D6, δ):
−229.6
layer was transferred to a 50 mL Schlenk flask and hexanes ppm, (1J119Sn-117Sn = 3703 Hz). Note: additional Sn couplings not
removed in vacuo, which resulted in the formation of white assigned. EA: Anal. Calc. C, 50.50; H, 4.24; Found. C, 45.31; H,
coloured powder. Yield = 77.0 % (0.45 g).
1H NMR (400 MHz, C6D6, δ): 7.40 (d, 4H, J = 8.5 Hz, 3J119Sn-H
= 29 Hz, 3J117Sn-H = 21.5 Hz), 6.81 (d, 4H, J = 8.5Hz), 6.12 (s, 2H,
4.09.
Poly-(di-n-butyl-alt-di-(4-methoxyphenyl)stannane (10): In
(0.35 g, 1.05 mmol) was
J119Sn-H = 954 Hz, J117Sn-H = 912 Hz), 3.29 (s, 6H) ppm. 13C {1H} a 100 mL Schlenk flask, compound
6
NMR (100 MHz, C6D6, δ): 160.76, 138.65 (2JC-Sn = 23.7 Hz), added and dissolved in 15 mL Et2O. In a separate 100 mL
125.40, 114.65 (3JC-Sn = 29.3 Hz), 54.20 ppm. 119Sn NMR (149 Schlenk flask wrapped with aluminum foil, (n-Bu)2Sn(NEt2)2
MHz, C6D6, δ): −229.6 (J119Sn-117Sn = 696 Hz) ppm. LRMS-DART (0.40 g, 1.05 mmol) was added and dissolved in 10 mL Et2O.
(m/z): [M+]+H. Calc 337.01; Found 337.0.
Both of the solutions were cooled down to 0 °C for 20 min
before the rapid addition of dihydride solution to the amine
solution using a syringe. The reaction mixture was allowed to
Di-hydride-di-(4-(trifluoromethyl)phenylstannane (7): In a
stir for 3 h at 0 °C, after which the solvent was removed in
100 mL Schlenk flask, compound
5 (0.34 g, 1.74 mmol) was
vacuo to produce a yellow coloured waxy product. The crude
product was dissolved in 10 mL THF and precipitated out from
60 mL cold hexanes to obtain a yellow powder, 10. Yield = 75.0
% (0.44 g).
1H NMR (400 MHz, C6D6, δ): 7.66 – 7.50 (bm, 4H, H4), 6.87
– 6.68 (bm, 4H, H3), 3.34 (s, 6H, H1), 1.63 – 1.62 (bm, 8H, H8,
H9), 1.44 – 1.42 (bm, 4H, H7), 0.95 – 0.88 (bm, 6H, H6) ppm.
13C {1H} NMR (100 MHz, C6D6, δ): 160.06 (C2), 139.29 (C4),
130.70 (C5), 114.56 (C3), 54.05 (C1), 32.84 (C8), 27.61 (C7),
13.55 (C9), 8.74 (C6) ppm. 119Sn NMR (149 MHz, C6D6, δ):
added and dissolved in 5 mL of EtOH and placed into an ice
bath. In another 50 mL Schlenk flask, excess NaBH4 (0.27 g,
17.41 mmol) was added and dissolved in 12 mL of EtOH and
placed into an ice bath. In a separate 50 mL round bottom, 25
mL of distilled water was degassed at 0
was prepared. The solution of NaBH4 was added dropwise via
cannula to the Schlenk flask containing compound , which
resulted in the clear white reaction mixture turning yellow.
The reaction mixture was allowed to stir for 1 h at 0 C, after
°C while the hydride
5
°
which 20 mL of hexanes were added. Then, 10 mL of distilled
degassed water was added dropwise. The reaction mixture
6 | J. Name., 2012, 00, 1-3
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DOI: 10.1039/C8DT03043J
Journal Name
188.8 ((n-Bu)2Sn),
ARTICLE
−
Calc. C, 46.69; H, 5.70; Found. C, 41.64; H, 5,34.
−
208.6 ((OMeC6H4)2Sn) ppm. EA: Anal.
1995, 117, 9931–9940.
B. Marciniec, New J. Chem., 1997, 21, 815–824.
11
12
M. Trummer, F. Choffat, P. Smith and W. Caseri, Macromol.
Rapid Commun., 2012, 33, 448–460.
Poly-(di-n-butyl-alt-di-(4-(trifluoromethyl)phenyl)stannane
13
14
D. Miles, T. Burrow, A. Lough and D. Foucher, J. Inorg.
Organomet. Polym. Mater., 2010, 20, 544–553.
M. Trummer, F. Choffat, M. Rami, P. Smith and W. Caseri,
Phosphorus, Sulfur Silicon Relat. Elem., 2011, 186, 1330–
1332.
(
11): In a 100 mL Schlenk flask, compound 7 (0.27 g, 0.66
mmol) was added and dissolved in 15 mL Et2O. In a separate
100 mL Schlenk flask wrapped with aluminum foil, (n-
Bu)2Sn(NEt2)2 (0.25 g, 0.66 mmol) was added and dissolved in 3
mL Et2O. Both of the solutions were cooled to 0 °C for 20 min
before the rapid addition of dihydride solution to the amine
15
16
17
18
19
20
21
22
23
24
25
26
27
M. Okano, N. Matsumoto, M. Arakawa, T. Tsuruta and H.
Hamano, Chem. Commun., 1998, 1799–1800.
T. Imori and T. D. Tilley, J. Chem. Soc. Chem. Commun.,
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solution using a syringe. The reaction mixture was allowed to
stir for 3 h at 0 °C. After the elapsed time, solvent was
removed in vacuo to produce a yellow coloured waxy product.
The crude product was dissolved in 10 mL THF and
precipitated out from 60 mL cold hexanes to obtain yellow
powder, 11. Yield = 43 % (0.18 g).
1H NMR (400 MHz, C6D6, δ): 7.39 (bd, 8H, H3 and H4, J =
46.8 Hz), 1.59 – 1.46 (bm, 8H, H8, H9), 1.30 – 1.15 (bm, 8H,
H7), 0.86 – 0.69 (bm, 6H, H6) ppm. 13C {1H} NMR (100 MHz,
V. Y. Lu and T. D. Tilley, Macromolecules, 2000, 33, 2403–
2412.
P. Braunstein and X. Morise, Chem. Commun., 1995, 7333,
1455.
N. R. Neale and T. D. Tilley, J. Am. Chem. Soc., 2002, 124,
3802–3803.
2
F. Choffat, P. Smith and W. Caseri, J. Mater. Chem., 2005,
15, 1789–1792.
C6D6, δ): 145.0.3 (C5), 138.09 (C4), 130.96 (C2, JC-F = 32.6 Hz),
1
125.04 (C3), 124.31 (C1, JC-F = 272.6 Hz), 32.50 (C8), 27.34
(C7), 13.16 (C6), 11.80 (C9) ppm. 119Sn NMR (149 MHz, C6D6,
F. Choffat, P. Smith and W. Caseri, Adv. Mater., 2008, 20,
2225–2229.
δ): −180.7 ((n-Bu)2Sn), −
213.9 ((CF3C6H4)2Sn) ppm. 19F NMR
M. Trummer, F. Choffat, P. Smith and W. Caseri, Macromol.
Rapid Commun., 2012, 33, 448–460.
(C6D6, δ):
−
62.9 (s, CF3) ppm. EA: Anal. Calc. C, 41.17; H, 4.08;
Found.
C, 43.08; H, 4.33.
A. Khan, S. Komejan, A. Patel, C. Lombardi, A. J. Lough and
D. A. Foucher, J. Organomet. Chem., 2015, 776, 180–191.
S. Harrypersad and D. Foucher, Chem. Commun., 2015, 51,
7120–7123.
Acknowledgements
The author thanks Professor Rob Gossage for his editorial
assistance and the NSERC Discovery program for support of
this work.
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Notes and references
‡ Additional data is found in the SI material associated with this
work. The crystallographic data for compound 4 was deposited
with Cambridge structural database (CCDC 1858149).
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