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H.K. Sharma et al. / Inorganica Chimica Acta xxx (2017) xxx–xxx
the five-coordinated tin atoms [16]. The magnitude of 1J
117Sn-117Sn) coupling constant of 7835 Hz for 11 is significantly
of the solution became dark red with the formation of a tin mirror.
The 119Sn NMR displaced a new resonance at 43.5 ppm due the for-
mation of the stannylene trapped adduct 1,1-di-tbutyl-3,4-
dimethyl-1-stannacyclopent-3-ene, 4 [5], in 20% yield along with
the appearance of a resonance at 110.5 ppm due to distannane 2.
In a separate reaction, the stannylene trapped adduct 4 was not
formed from the photolysis experiment of 1 with 2, 3-dimethyl-
1,3-butadiene.
(
lower than 14980 Hz observed for Me4Sn2(OAc)2 [17]; its IR spec-
trum displayed a strong band at 1550 cmꢀ1 attributed to ʋ (CO)
suggesting that the carboxylate ligand is bridging the two tin
atoms, and its 13C NMR spectrum displays
a resonance at
183.5 ppm due to the carbonyl resonance of acetate group. The
molecular structure of the tin carboxylate is shown in Fig. 3 with
important bond lengths (Å) and angles (o).
The two tin atoms are unsymmetrically bridged by the acetate
group with two unequal Sn-O bond distances of 2.290(3) Å and
2.313(3) Å forming an 8-membered ring. The Sn-Sn bond distance
of 2.7402(3) Å is significantly longer than the Sn-Sn distance of
2.691(1) Å in Ph4Sn2(OAc)2 [15], reflecting the steric bulk of the
t-butyl groups. The geometry around both the tin atoms is trigonal
bipyramidal, the basal plane defined by two tbutyl group and other
tin atom and two oxygen atoms of the acetate groups occupying
the axial positions.
4.3. Thermolysis of 1 in the presence of benzil
A Pyrex NMR tube was charged with 0.15 g, 0.19 mmol of 1, and
0.08 g (0.38 mmol) of benzil in 0.4 mL of toluene. The tube was
sealed under vacuum and heated in an oven at 100 °C. The progress
of the reaction was monitored by 119Sn. After 2 d the color of the
solution became light yellow and the tristannane of 1 was com-
pletely converted into distannane 2. No stannylene trapped benzil
adduct was observed in NMR spectroscopy.
4.4. Thermolysis of 1 in the presence of sulfur
3. Conclusions
A Pyrex NMR tube was charged with 0.10 g, 0.13 mmol of 1 and
0.012 g (0.38 mmol) of sulfur in 0.4 mL of C6D6. The tube was
sealed under vacuum and heated in an oil bath at 60 °C. The pro-
gress of the reaction was monitored by 119Sn and 13C NMR spec-
troscopy. After 20 h of the thermal reaction, dithiastannetane 5
showing a 119Sn resonance at 123.9 ppm was formed in 90% yield,
along with trace amounts of tristannane 1 and distannane 2
remaining in the reaction mixture. Further heating for 4 h pro-
duced a small intensity 119Sn signal at 106.3 ppm which is due to
Thermolysis of the title compound 1 results in the slow elimina-
tion of Bu2Sn: which may be efficiently trapped by a variety of
t
materials. This is in contrast to the photochemical treatment of
1, where the loss of tBu2Sn: is more rapid, but not readily trapped.
The title compound has the potential to be a useful precursor
reagent for extension of group 14 catenanes, and when successful
the resulting products, PhMe2Si-tBu2Sn-tBu2Sn-tBu2SnCl, 9, and
PhMe2Si-tBu2Sn-tBu2Sn-tBu2Sn-SiPhMe2, 10, appear to be thermo-
dynamically and kinetically stable. However, during the reactions
to form such interesting materials much alternative chemistry
tetra-tbutyldistannathiane,
6,
Cl-tBu2Sn-S-SnBut2–Cl
[10b],
t
produced in trace amounts due to the insertion of S atom in the
Sn-Sn bond of 2.
occurs involving Sn-Sn bond cleavage and Bu2Sn: elimination.
4. Experimental section
4.5. Thermolysis of 1 in the presence of diphenyl disulfide
All manipulations were carried out under Argon atmosphere
using Schlenk or vacuum line techniques. THF was distilled under
nitrogen from benzophenone ketyl prior to use. Other solvents,
hexanes, benzene and toluene were dried over sodium metal and
distilled before use. Tristannane 1 and distannane 2 were synthe-
sized by the reported methods [6,12c]. NMR spectra were recorded
on 300 MHz Bruker spectrometer in C6D6. All reactions mixtures
were freeze-pumpthaw degassed before flame sealing of the
NMR tube.
A Pyrex NMR tube was charged with 0.14 g, 0.18 mmol of 1 and
0.039 g (0.18 mmol) of Ph2S2 in 0.4 mL of C6D6. The tube was
sealed under vacuum and heated in an oil bath at 60 °C. The pro-
gress of the reaction was monitored by 119Sn and 13C NMR spec-
troscopy. After 10 h of thermolysis we initially observed the
formation of S-S inserted product tBu2Sn(SPh)2, 7, displaying a
119Sn resonance at 54.4 ppm [5]. After further heating for 10 h,
the starting material 1 was completely consumed, and a 119Sn
t
NMR resonance appeared at 68.7 ppm showing the formation of -
Bu2Sn(Cl)SPh, 8.
4.1. Thermolysis of 1
t
t
4.6. Thermal reaction of Bu2Sn(SPh)2 with Bu2SnCl2
In a typical experiment, a Pyrex NMR tube was charged with
0.15 g, 0.19 mmol of 1 in 0.5 mL of C6D6. The tube was sealed under
vacuum and heated in an oven at 110 °C. The progress of the reac-
tion was monitored by 119Sn and 13C NMR spectroscopy. After 2 d
of thermal reaction the color of the solution became light brown
with little black deposits of elemental tin and the 119Sn NMR
showed the disappearance of resonances at 114.5 and ꢀ0.8 ppm
due to tristannane 1 and appearance of a single new resonance
at 110.5 ppm indicating the complete conversion of 1 to distan-
nane 2.
A Pyrex NMR tube was charged with 0.34 g, 0.75 mmol of tBu2-
Sn(SPh)2 and 0.23 g (0.75 mmol) of tBu2SnCl2 in 0.4 mL of C6D6. The
tube was sealed under vacuum and heated in an oil bath at 60 °C.
After 4 h of thermolysis, the 119Sn NMR of the reaction showed
only one resonance 68.7 ppm due to the formation of tBu2SnCl
(SPh), 8.
4.7. Reaction of 1 with PhMe2SiLi
A flame dried 250 mL three-necked flask equipped with drop-
ping funnel and a condenser was charged with 0.1.4 g (1.8 mmol)
of tristannane 1 in 60 mL of hexanes and maintained at ꢀ25 °C.
To this was added slowly a brown solution of PhMe2SiLi (prepared
from 0.25 g, 0.92 mmol of PhMe2SiSiMe2Ph and four-fold excess Li
in 25 mL of THF) via a dropping funnel. The addition of PhMe2SiLi
was conducted over a period of 30 min. The temperature of the
reaction mixture was raised slowly to room temperature and the
4.2. Thermolysis of 1 in the presence of 2, 3-dimethyl-1,3-butadiene
Pyrex NMR tube was charged with 0.15 g, 0.19 mmol of 1 and
0.016 g (0.19 mmol) of 2,3-dimethyl-1,3-butadiene in 0.4 mL of
C6D6. The tube was sealed under vacuum and heated in an oven
at 110 °C. The progress of the reaction was monitored by 119Sn
and 13C NMR spectroscopy. After 3 d of thermal reaction the color
Sharma, Hemant K.
