Reactivity of sulfonyl-containing compounds with ditetrelenes

Article abstract of DOI:10.1039/c7dt02374j

The addition of a variety of sulfones and a sulfoxide to ditetrelenes (a disilene and a digermene) was examined. The reaction of benzenesulfonyl chloride with tetramesityldisilene or tetramesityldigermene results in the formation of the 1,2-addition products, 2-chlorotetramesityldisilyl- or digermylbenzenesulfinate. The addition of p-toluenesulfonyl chloride to the disilene gave the analogous product, 2-chlorotetramesityldisilyl p-toluenesulfinate. In contrast, benzenesulfonyl fluoride, diphenyl and dimethyl sulfone did not react with either the disilene or the digermene. The unprecedented formation of the sulfinates reveals a selective 2-electron reduction of the sulfur centres using ditetrelenes. The addition reactions of sulfonyl compounds illustrates the potential of ditetrelenes to serve as reducing agents which react rapidly, at room temperature under mild conditions. The reaction of tetramesityldisilene with diphenyl sulfoxide resulted in the formation of tetramesityloxadisilirane and with benzene sulfonic acid resulted in the formation of 1,1,2,2-tetramesityldisilyl benzenesulfonate.

Full text of DOI:10.1039/c7dt02374j

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Reactivity of sulfonyl-containing compounds with
ditetrelenes†‡
Cite this: DOI: 10.1039/c7dt02374j
a
Nada Y. Tashkandi,a,b Jeremy L. Bourquea and Kim M. Baines
*
The addition of a variety of sulfones and a sulfoxide to ditetrelenes (a disilene and a digermene) was exam-
ined. The reaction of benzenesulfonyl chloride with tetramesityldisilene or tetramesityldigermene results
in the formation of the 1,2-addition products, 2-chlorotetramesityldisilyl- or digermylbenzenesulfinate.
The addition of p-toluenesulfonyl chloride to the disilene gave the analogous product, 2-chlorotetra-
mesityldisilyl p-toluenesulfinate. In contrast, benzenesulfonyl fluoride, diphenyl and dimethyl sulfone did
not react with either the disilene or the digermene. The unprecedented formation of the sulfinates reveals
a selective 2-electron reduction of the sulfur centres using ditetrelenes. The addition reactions of sulfonyl
compounds illustrates the potential of ditetrelenes to serve as reducing agents which react rapidly, at
room temperature under mild conditions. The reaction of tetramesityldisilene with diphenyl sulfoxide
resulted in the formation of tetramesityloxadisilirane and with benzene sulfonic acid resulted in the for-
mation of 1,1,2,2-tetramesityldisilyl benzenesulfonate.
Received 30th June 2017,
Accepted 18th September 2017
DOI: 10.1039/c7dt02374j
rsc.li/dalton
Introduction
The use of main group compounds as reducing agents is well-
established and includes common reagents such as PR3,
R3SnH, and SnCl2. However, the notion of ditetrelenes as redu-
cing agents, although known, has not been well-explored.1 For
example, Scheschkewitz et al. have reported the reductive clea-
vage of carbon monoxide by the addition of lithium disilenide
(Tip)2SivSi(Tip)Li(dme)2 (Tip = 2,4,6-triisopropylphenyl, dme =
dimethoxyethane) to CO at room temperature.2 We also reported
the facile and clean, albeit unexpected, two electron reduction of
nitromethane by both a disilene and a digermene (Scheme 1).3
Although other examples exist where a disilene has formally
reduced a nitrogen in reaction with an unsaturated nitrogen-
containing functional group,4,5 we were interested in exploring
whether other functional groups could also be readily reduced
using ditetrelenes. Sulfur compounds, where the sulfur oxi-
dation number can vary from +6 to −2, appeared to be excellent
candidates to study in this regard. Thus, the reactivity of a
variety of compounds with sulfur in higher oxidation states, i.e.
Scheme 1 Reduction of nitromethane using 1 and 2.
Scheme 2 Reaction 1 with p-toluenesulfonyl azide.
sulfonyl compounds, RSO2X where R = Ph or Tol and X = Cl, F,
OH, or Ph, and a sulfoxide, towards ditetrelenes has been inves-
tigated. Notably, only one example of the addition of a sulfonyl
derivative to a ditetrelene has been reported to date; the
addition of p-toluenesulfonyl azide to tetramesityldisilene to
give 5 was reported by West and co-workers (Scheme 2).5 In this
case, reduction of nitrogen, rather than sulfur, took place.
aDepartment of Chemistry, University of Western Ontario, London, Ontario,
Canada N6A 5B7. E-mail: kbaines2@uwo.ca
bDepartment of Chemistry, King Abdul Aziz University, Jeddah, Saudi Arabia
†In recognition of the many creative contributions by Professor Phil P. Power to
main group chemistry.
‡Electronic supplementary information (ESI) available: Selected procedures, 1H
and 13C{1H} NMR spectra and crystallographic data for compounds 6, 7, 8 and
10; atomic coordinates and energies for optimized geometries of compounds 6,
10, 12 and 13. CCDC 1479171–1479174. For ESI and crystallographic data in CIF
or other electronic format see DOI: 10.1039/c7dt02374j
Results
There was no reaction between diphenyl or dimethyl sulfone
with disilene 1. In contrast, the addition of benzene- or
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p-toluenesulfonyl chloride to a bright yellow solution of disi- atoms exhibit pyramidal geometry (for example, the sulfur in 6
lene 1 dissolved in hexanes or C6D6 at room temperature gave is displaced from the plane of the attached atoms by
a colourless solution and removal of the solvent gave a white 0.6882(19) Å), indicating the presence of a stereochemically
solid. The products were purified by recrystallization from a active lone pair. The non-bridging oxygen–sulfur bond dis-
saturated hexanes solution at low temperature to yield colour- tances are 1.462(3) and 1.4601(17) Å, for 6 and 7, respectively,
less solids which were characterized by multinuclear and mul- indicative of terminal oxygen–sulfur bonds, while the bridging
tidimensional NMR spectroscopy and mass spectrometry. The oxygen–sulfur bonds have lengths of 1.637(2) and 1.6318(14) Å
structures of 6 and 7 in the solid state were unequivocally for 6 and 7, respectively, that are longer, as expected, than the
determined by single crystal X-ray diffraction as 2-chlorotetra- terminal oxygen–sulfur bonds. Compounds 6 and 7 are air-
mesityldisilyl benzenesulfinate, 6, and 2-chlorotetramesityldi- and moisture-sensitive and decompose upon exposure to air or
silyl p-toluenesulfinate, 7 (Scheme 3 and Fig. 1; see the ESI‡ upon chromatography.
for the molecular structure of 7).
Due to the presence of the chiral sulfur centre, the two
The structural metrics of 6 and 7 are similar and the bond mesityl groups on each silicon of 6 and 7 are diastereotopic.
angles and bond lengths for both adducts are within expected Accordingly, the 1H NMR spectra of 6 and 7 reveal the presence
ranges: the Si–Cl bond lengths (2.0981(13) Å for 6 and of four nonequivalent mesityl groups in addition to an aryl
2.0949(8) Å for 7), the Si–O bond lengths (1.700(2) Å for 6 and group. The signals assigned to the o-methyl groups on the
1.6953(14) Å for 7) and the Si–Si bond distances (2.3993(14) Å mesityl groups in each spectrum are broad due to the slow
for 6 and 2.3997(10) Å for 7) are not significantly different rotation of the mesityl groups on the NMR time scale. Heating
from the average Si–Cl (2.065 0.046 Å), Si–O (1.628 0.032 Å) the sample to 70 °C resulted in sharpening of the signals in
and Si–Si (2.363 0.035 Å) bond lengths, respectively, found in the 1H NMR and 13C{1H} NMR spectra of 6 and 7.
similar four-coordinate silicon compounds on the basis of a
To explore the effect of the halide on the outcome of the
search of the Cambridge Structural Database.6 Both sulfur reaction, the addition of benzenesulfonyl fluoride to disilene 1
was also examined; no reaction was observed.
The addition of benzenesulfonic acid to a yellow solution of
disilene 1 in hexanes yielded a clear, colourless solution
1
within a few minutes. The H NMR spectrum of 8 showed two
sets of mesityl signals and a singlet at 5.71 ppm, which was
assigned to a Si–H moiety. Accordingly, the IR spectrum of 8
revealed an absorption at 2200 cm−1, which is in the range
typical for the stretching vibration of an Si–H bond. The strong
absorption at 1349 cm−1 in the IR spectrum of 8 was assigned
to the terminal SO bond stretching vibration, and the absorp-
Scheme 3 Synthesis of arylsulfinates 6 and 7.
tion at 909 cm−1 was assigned to the bridging S–O bond
stretching vibration. The structure of 8 was confirmed by X-ray
crystallography as 1,1,2,2-tetramesityldisilyl benzenesulfonate
(Scheme 4 and Fig. 2). All bond lengths and angles are within
normal ranges.
The addition of excess diphenyl sulfoxide to a bright yellow
solution of disilene 1 in hexanes at room temperature gave a
colourless solution. Removal of the solvent yielded a white
solid, which revealed the presence of tetramesityloxadisilirane,
Mes4Si2O, 9,7 and diphenylsulfide as confirmed by 1H NMR
spectroscopy (Scheme 5).
To compare the addition of sulfonyl compounds to tetra-
mesityldisilene with a heavier congener, the reaction of sulfonyl
compounds with tetramesityldigermene (2) was also examined.
Fig. 1 Displacement ellipsoid plot of 6. Ellipsoids are at the 50% prob-
ability level and hydrogen atoms were omitted for clarity. Selected bond
lengths (Å) and angles (°): Si1–Cl1 = 2.0981(13), Si1–Si2 = 2.3993(14),
S1–O2 = 1.462(3), S1–O1 = 1.637(2), Si2–O1 = 1.700(2); Cl1–Si1–Si2 =
99.86(5), O2–S1–O1 = 105.23(14), O2–S1–C37 = 105.88(16), O1–Si2–Si1
= 101.47(9), S1–O1–Si2 = 134.54(15).
Scheme 4 Synthesis of arylsulfonate 8.
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Discussion
The lack of reaction between dimethyl and diphenyl sulfone
and disilene 1 and digermene 2 is interesting. Although
addition reactions are not known between sulfones and
alkenes,8 it did not seem unreasonable that sulfones may react
with ditetrelenes given that ditetrelenes are more reactive than
alkenes and often exhibit reactivity which is unprecedented in
alkene chemistry.1,9 For example, the addition of nitro com-
pounds to alkenes, in general, proceeds through the nitronate
isomer,10 whereas the addition of the same functional group
to ditetrelenes gives a [3 + 2] cycloadduct.3 Furthermore, the
possibility of forming a sulfurane (oxide) from the reaction
with a sulfone was appealing. The lack of reactivity between
the sulfones and the ditetrelenes may be attributable to the
reduction potential of sulfones in comparison to nitro com-
pounds. The standard reduction potential for diphenyl sulfone
is about −2.42 V versus Fc/Fc+,11 whereas that for nitrobenzene
is −1.49 V versus Fc/Fc+.12,13 The electronic structure of sul-
fones, with two highly polarized oxygen–sulfur bonds having
important contributions from negative (reciprocal) hyper-
conjugation interactions,14 in comparison to nitroalkanes is
apparently not amenable to reaction, even with ditetrelenes, to
give a sulfurane (oxide).
Fig. 2 Displacement ellipsoid plot of 8. Ellipsoids are at the 50% prob-
ability level and hydrogen atoms were omitted for clarity except the
hydrogen on Si1. Selected bond lengths (Å) and angles (°): Si1–Si2 =
2.3757(10), Si1–H1 = 1.46(2), Si2–O1 = 1.7127(16), S1–O3 = 1.4253(17),
S1–O2 = 1.4274(16), S1–O1 = 1.5486(16); C1–Si1–Si2 = 110.96(7), C1–
Si1–H1 = 106.3(8), C10–Si1–H1 = 107.2(8), Si2–Si1–H1 = 96.6(8), O1–
Si2–Si1 = 106.10(6).
In contrast, arylsulfonyl chlorides readily react with ditetre-
lenes, albeit to give β-chlorosulfinates and not a cycloadduct.
Notably, arylsulfonyl chlorides are more easily reduced than
sulfones (−0.33 V versus Fc/Fc+).11b,15 We propose the following
mechanism to account for the formation of the sulfinate
adducts 6, 7 and 10. Nucleophilic attack by one of the sulfonyl
oxygens on the ditetrelene would give intermediate 11, consist-
ent with the mechanism postulated for the addition of water
(or alcohols) to disilenes.16 The nucleophilic addition of water
to disilenes is strongly exothermic with a small activation
energy.17 In a second step (if the reaction is not concerted), the
Scheme 5 Reaction of 1 with diphenyl sulfoxide.
In a similar fashion, the addition of benzenesulfonyl chloride silicon (or germanium) attacks the chlorine, reducing the
to digermene 2 in THF at room temperature produced 2-chloro- sulfur atom and giving the final product (Scheme 7). The
tetramesityldigermyl benzenesulfinate 10 (Scheme 6), as con- addition of p-toluenesulfonyl azide to tetramesityldisilene was
firmed by X-ray crystallography. All bond lengths and angles of also proposed to be stepwise, where nucleophilic attack of
10 are within normal ranges. The sulfur exhibits pyramidal oxygen on the disilene was followed by ring closure and simul-
geometry similar to 6 and 7; in this case, the sulfur is dis- taneous loss of N2 resulting in the formation of 5.5
placed from the plane by 0.6615(20) Å (see the ESI‡ for the
molecular structure of 10).
The proposed mechanism for the formation of the sulfi-
nates 6, 7 and 10 is consistent with the observed lack of reac-
Similar to disilene 1, no reaction was observed upon the tivity of benzenesulfonyl fluoride towards tetramesityldisilene
addition of benzenesulfonyl fluoride and diphenyl sulfone to and -digermene. The nucleophilicity of a terminal oxygen in
digermene 2.
benzenesulfonyl fluoride is expected to be lower than that in
Scheme 6 Synthesis of arylsulfinate 10.
Scheme 7 Proposed mechanism for the formation of the arylsufinates.
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benzenesulfonyl chloride, reducing the rate of the first step. resulting from the addition of sulfonyl chlorides to alkenes,
Furthermore, the low polarizability of fluorine in comparison has the same oxidation number (+6) as the starting sulfonyl
to chlorine would further inhibit the reaction, as the halide chloride whereas, in the β-chlorosulfinate esters, resulting
abstraction would not be facile for the fluoride derivative.
from the addition of sulfonyl chlorides to a ditetrelene, the
The reaction of the sulfonyl chlorides with the ditetrelenes sulfur is reduced from the +6 to the +4 oxidation number. The
gives an acyclic isomer, rather than a cyclic sulfurane. The rela- selective two electron reduction of sulfonyl chlorides mirrors
tive energies of the two isomeric pairs (6/12 and 10/13; the same reduction of nitroalkanes by ditetrelenes.
Chart 1) as calculated at the M06/6-311+G* level of theory18 are
The sulfur atom in diphenyl sulfoxide is also reduced by
consistent with this observation: sulfurane 12 is 92.1 kJ mol−1 disilene 1 going from the +4 to the +2 oxidation state, albeit
higher in energy than the 1,2-adduct 6, and sulfurane 13 is the reaction follows a different pathway. In this case, an oxygen
119.2 kJ mol−1 higher in energy than the 1,2-adduct 10. is abstracted to give an oxadisilirane and the corresponding
Attempts to optimize the isomeric 4-membered ring sulfurane sulfide. The reduction of sulfoxides to their corresponding
oxide structures (nominally through a 1,2-dipolar addition) sulfides has been reported using both main group compounds
were unsuccessful; the structures eventually optimized to the and metal complexes.23 The addition of benzenesulfonic acid
5-membered sulfuranes for both the silicon and the germa- also exhibits different reactivity in comparison to the sulfonyl
nium analogs.
chloride; however, this is completely expected. Addition across
It is interesting to compare the observed reactivity of di- the OH bond of the sulfonic acid is observed, a common reac-
tetrelenes towards sulfonyl chlorides with the chemistry of the tion mode with hydroxyl-containing compounds.1 Not surpris-
analogous alkenes. Although the addition of organosulfonyl ingly, the sulfur in benzenesulfonate 8, has the same oxidation
chlorides to alkenes in the presence of a peroxide to form a number (+6) as the starting sulfonic acid.
β-chlorosulfone has been known for some time,19 the yields of
Sulfinates are an important class of molecules which have
the reactions are often low due to competing reactions.19,20 recently been exploited in organic synthesis due to their versa-
However, in the presence of a catalytic amount of dichlorotris tility and accessibility and various procedures have been
(triphenylphosphine)ruthenium, the addition of alkyl- and reported for their preparation.24 Most relevant to the current
arylsulfonyl chlorides to alkenes at high temperature (120 °C) discussion is the reduction of sulfonyl chlorides without an
proceeds cleanly in high yield (Scheme 8).21 The use of the Ru(III) α-hydrogen using trialkoxy-25 or triarylphosphines26 and an
complex, [Cp*RuCl2(PPh3)] as a pre-catalyst in combination amine. The generation of silylated/germylated sulfinates 6, 7
with AIBN improved the yield of the β-chlorosulfones at lower and 10, via the addition of sulfonyl chlorides to ditetrelenes,
temperatures (60 °C) and with higher turnover numbers.22 The offers an alternative, facile route for the formation of sulfi-
reaction of sulfonyl chlorides with alkenes is believed to nates, which proceeds without the use of heat or a catalyst
proceed via a radical redox mechanism.
under very mild conditions. However, given that disilene 1 and
In contrast, the addition of sulfonyl chlorides to ditetre- digermene 2 are not commercially available and are quite reac-
lenes proceeds almost instantly without a catalyst or heat to tive requiring manipulation under inert conditions, the use of
give β-chlorosulfinates. The formation of the strong Si–O bond ditetrelenes for the synthesis of sulfinates will be limited to
and a difference in reaction mechanisms (radical versus hetero- specialty applications which also require inert conditions.
lytic) may account, at least in part, for the difference in the pro-
ducts formed. Notably, the sulfur in the β-chlorosulfones,
Conclusions
In conclusion, the addition of sulfonyl chlorides to tetra-
mesityldisilene and tetramesityldigermene leads to the facile for-
mation of the 1,2-addition products, 2-chlorotetramesityldisilyl
benzene(p-toluene)sulfinate and 2-chlorotetramesityldigermyl
benzenesulfinate, respectively. On the other hand, the addition
of a sulfonyl fluoride or a sulfone to both disilene and diger-
mene gave no reaction. The formation of sulfinates (6, 7
and 10) reveals a mild two-electron reduction of the sulfur
centres using ditetrelenes. In the case of a sulfoxide, oxygen
abstraction by the disilene was observed and addition across
an OH was observed upon the addition of a sulfonic acid to a
disilene. Although oxygen abstraction and the σ-addition of a
hydroxyl group are well-known reactivity motifs in ditetrelene
chemistry, the reduction of sulfonyl chlorides to give
β-chlorosulfinates is unprecedented and could be exploited in
synthetic or materials chemistry.
Chart 1 Sulfuranes 12 and 13.
Scheme 8 Reaction of alkenes with sulfonyl chlorides.
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Colourless, clear crystals 7 (35 mg, 50%) m.p. 172–174 °C;
1H NMR (C6D6, 600 MHz, 70 °C) δ 7.54 (br s, 2H, Ph o-CH),
6.84 (m, 2H, Ph m-CH), 6.76 (s, 2H, Mes m-CH), 7.00 (br s, 4H,
Experimental
General experimental details
All air sensitive reactions were performed under an inert atmo- Mes m-CH), 6.60 (s, 2H, Mes m-CH), [2.42 (br s, Mes o-CH3),
sphere of argon or nitrogen using standard Schlenk tech- 2.24 (br s, Mes o-CH3), 2.12 (s, Mes o-CH3), 2.08 (s, Mes
niques or a glove box. Hexanes and THF were obtained from a p-CH3), 2.07 (s, Mes p-CH3), 2.01 (s, Mes p-CH3), 1.94 (s, Tol
solvent purification system (SPS-400-5, Innovative Technology p-CH3) all together 39H]; 13C NMR (C6D6, 150 MHz, 70 °C)
Inc.). NMR spectra were recorded on a Varian Inova 400 or an δ 147.50 (Ph i-C), 145.20 (br s, Mes o-C), 142.18 (Ph p-C),
Inova 600 MHz NMR spectrometer. The NMR standards used 140.20 (Mes p-C), 139.95 (Mes p-C), 139.68 (Mes p-C), 139.57
1
were residual C6D5H (7.15 ppm) for H NMR spectra and the (Mes p-C), 131.96 (br s, Mes i-C), 130.17 (Mes m-CH), 129.97
central signal of C6D6 (128.00 ppm) for 13C{1H} NMR spectra. (br s, Mes m-CH), 129.44 (Ph m-CH), 124.79 (Ph o-CH), 25.39
1H, 13C and 29Si NMR signals were assigned using 1H–1H (br s, Mes o-CH3), 21.13 (Tol. p-CH3), 21.00 (Mes p-CH3), 20.90
gCOSY, 1H–13C gHSQC, 1H–13C gHMBC and/or 29Si–1H (Mes p-CH3), 20.87 (Mes p-CH3), 20.81 (Mes p-CH3); 29Si NMR
gHMBC NMR spectroscopy. IR spectra were recorded (cm−1
)
(C6D6, 119 MHz, 70 °C) δ −4;32 FTIR (thin film, cm−1) 3017 (s),
from thin films on a Bruker Tensor 27 FT-IR spectrometer. 2958 (s), 2921 (s), 1603 (s), 1449 (s), 1139 (m), 824 (s), 757 (s);
ESI-TOF mass spectra were obtained using a Bruker micrOTOF high resolution ESI-MS m/z for C43H51O2NaSi2SCl calc.
instrument. Mass spectral data are reported in mass-to-charge 745.2735 found 745.2749.
units, m/z. X-ray data were obtained using a Bruker Apex II
27
28
Addition of benzenesulfonic acid to tetramesityldisilene
Diffractometer. Ge3Mes6
and (Me3Si)2SiMes2
were syn-
thesized according to the literature procedures. Due to small Mes2Si(SiMe3)2 (100 mg, 0.24 mmol) was placed in a quartz
sample sizes and the air- and moisture-sensitivity of the tube, dissolved in hexanes (3 mL), and then placed in a quartz
samples, elemental analyses were not performed.
Dewar. The solution was irradiated (254 nm) for ∼18 h to give
a bright yellow solution. The solution was cooled to −60 °C
during the irradiation by circulating cold methanol. Excess
benzenesulfonic acid (23.7 mg, 0.15 mmol) was added to the
yellow solution at room temperature and the reaction was
Addition of benzenesulfonyl chloride (or p-toluenesulfonyl
chloride) to tetramesityldisilene (1)
Mes2Si(SiMe3)2 (50 mg, 0.12 mmol) was placed in a quartz allowed to stir. After 5 min, the solution became colourless.
tube, dissolved in hexanes (3 mL), and then placed in a quartz The hexanes were evaporated giving a pale yellow powder,
Dewar. The solution was irradiated (254 nm) for ∼18 h to give which was redissolved in a minimal amount of hexanes. The
a bright yellow solution. The solution was cooled to −60 °C flask was placed in the freezer (−20 °C) for 24 h. A fine precipi-
during the irradiation by circulating cold methanol. Excess tate formed which was isolated by centrifugation. The solid
benzenesulfonyl chloride (14 mg, 0.08 mmol) (or p-toluene- was triturated with pentane yielding colourless, clear crystals
sulfonyl chloride (13 mg, 0.08 mmol)) was added to the yellow of 8 (80 mg, 77%) White powder; m.p. 188–190 °C; 1H NMR
solution at room temperature and the mixture was allowed to (C6D6, 400 MHz) δ 7.82 (d, 2H, Ph o-H, J = 8 Hz), 6.89 (t, 1H, Ph
stir. After 5 min, the solution became pale yellow. The hexanes p-H, J = 7 Hz), 6.84 (t, 2H, Ph m-H, J = 8 Hz), [6.66 (s, Mes m-H)
were evaporated giving a pale yellow oil which was redissolved 6.63 (s, Mes m-H) all together 8H], 5.68 (s, 1H, Si–H), 2.30 (br s,
in a minimal amount of hexanes. 1H NMR spectroscopy 24H, Mes o-CH3), [2.06 (s, Mes p-CH3), 2.04 (s, Mes p-CH3)
revealed the presence of only one product. The solution was all together 12H]; 13C NMR (C6D6, 150 MHz) δ 145.51 (Mes
placed in the freezer (−20 °C) for 24 h to give colourless crys- o-C), 144.58 (Mes o-C), 140.63 (Ph i-C), 140.10 (Mes p-C),
tals, which were isolated by decantation. The solid was tritu- 139.12 (Mes p-C), 132.48 (Ph p-CH), 131.69 (Mes i-C), 129.99
rated with pentane yielding colourless, clear crystals of 6 (Mes m-CH), 129.96 (Mes m-CH), 129.94 (Mes m-CH), 129.93
(30 mg, 53%). m.p. 174–176 °C; 1H NMR (C6D6, 600 MHz, (Mes m-CH), 129.02 (br s, Mes m-CH), 128.99 (Mes m-CH),
70 °C) δ 7.59 (br s, 2H, Ph o-H), 7.00 (3H, Ph m-H + p-H), 6.75 128.54 (Ph m-CH), 127.92 (Ph o-CH), 24.72 (br s, Mes o-CH3),
(br s, 2H, Mes m-H), 6.69 (br, 4H, Mes m-H), 6.59 (s, 2H, Mes 24.67 (Mes o-CH3), 24.65 (Mes o-CH3), 21.04 (Mes p-CH3),
m-H), [2.40 (br s, Mes o-CH3), 2.21 (br s, Mes o-CH3), 2.11 (s, 21.12 (Mes p-CH3), 21.00 (Mes p-CH3), 20.98 (Mes p-CH3); FTIR
Mes p-CH3), 2.08 (s, Mes p-CH3), 2.07 (s, Mes p-CH3), 2.01 (s, (thin film, cm−1) 3022 (s), 2961 (s), 2920 (s), 2200 (m), 1604 (s),
Mes p-CH3) all together 36H]; 13C NMR (C6D6, 150 MHz, 70 °C) 1448 (s), 1350 (s), 1185 (s), 909 (s), 757 (s), 597 (s); 29Si NMR
δ 150.16 (Ph i-C), 144 (Mes o-C),29 140.25 (Mes p-C), 140.01 (C6D6, 119 MHz) δ 5 (Si–O), −55 (Si–H);32 high resolution
(Mes p-C), 139.72 (Mes p-C), 139.60 (Mes p-C), 131.69 (Mes i-C ESI-MS m/z for C42H50O3NaSi2S calc. 713.2917 found 713.2918.
+ Ph p-CH), 130.20 (Mes m-CH), 130.17 (Mes m-CH), 129.5 (br
Addition of diphenyl sulfoxide to tetramesityldisilene
s, Mes m-CH), 128.77 (Ph m-CH), 124.67 (Ph o-CH), 25 (Mes
o-CH3),30 20.99 (Mes p-CH3), 20.89 (Mes p-CH3), 20.87 (Mes Mes2Si(SiMe3)2 (50 mg, 0.12 mmol) was placed in a quartz
p-CH3), 20.81 (Mes p-CH3); 29Si NMR (C6D6, 119 MHz, 70 °C)31 tube, dissolved in hexanes (3 mL), placed in a quartz Dewar.
δ −4.19, −4.15; FTIR (thin film, cm−1) 2920 (br s), 1603 (s), The solution was irradiated (254 nm) for ∼18 h to give a bright
1445 (s), 1143 (m), 819 (m), 755 (m); high resolution ESI-MS yellow solution. The solution was cooled to −60 °C during the
m/z for C42H49O2NaSi2S35Cl calc. 731.2578 found 731.2568.
irradiation by circulating cold methanol. Excess diphenyl sulf-
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oxide (16 mg, 0.08 mmol) dissolved in hexanes (1 mL)
was added to the yellow solution at room temperature,
Conflicts of interest
the reaction mixture turned colourless immediately. There are no conflicts to declare.
Tetramesityloxadisilirane (9),6 Mes4Si2O, and diphenylsulfide
were observed as determined by 1H NMR spectroscopy.
Acknowledgements
Addition of benzenesulfonyl chloride to
tetramesityldigermene (2)
We thank NSERC (Canada) and the University of Western
Ge3Mes6 (100 mg, 0.107 mmol) was placed in a quartz tube33 Ontario for financial support and King Abdul Aziz University
and dissolved in THF (5 mL) and then irradiated (350 nm) in a (Saudi Arabia) for a scholarship to N. Y. T. and NSERC for a
quartz Dewar33 at −60 °C for ∼18 h to a give yellow solution. scholarship to J. L. B.
Excess benzenesulfonyl chloride (30 mg, 0.17 mmol) was
added to the yellow solution at room temperature and the reac-
tion was allowed to stir. After 5 min, the solution became
colourless. The solvent was evaporated giving a clear, colourless
References
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29 Chemical shift extracted from the 1H–13C gHMBC
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30 Chemical shift extracted from the 1H–13C gHSQC
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18 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. Scuseria,
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X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, 33 A quartz tube and Dewar were used but a Pyrex Dewar also
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can be used.
1
H. Nakai, T. Vreven, J. A. Montgomery, J. E. Peralta Jr.,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers,
of 10 at 6.69, 2.42, 2.40, 2.06, 1.20, 1.99 ppm in ratio of
1 : 0.06.
K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, 35 We did not observe a signal which could be assigned to the
K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, ipso-carbon of the phenyl ring.
J. Tomasi, M. Cossi, N. Rega, M. J. Millam, M. Klene, 36 The high-resolution ESI-MS data are for [M − Cl]+. We were
J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo,
R. Comperts, R. E. Stratmann, O. Yazyev, A. J. Austin,
R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin,
unable to obtain satisfactory high-resolution MS data of
M + Na+ due to overlap with an unknown contaminant or
an additional ion (i.e. M + H+).
K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, 37 A. D. Becke, J. Chem. Phys., 1993, 98, 5648.
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215.
This journal is © The Royal Society of Chemistry 2017
Dalton Trans.