The reaction of (tert-Butoxysilyl)methylmagnesium chlorides with some organotin and organosilicon monochlorides

Article abstract of DOI:10.1016/j.ica.2020.119555

Interaction between (tert-butoxysilyl)methylmagnesium chlorides of the general formula Me_3-n(t-BuO)_nSiCH₂MgCl, n = 1–3, with some organotin and organosilicon monochlorides has been studied. It has been found that the reaction of the Grignard reagents with trialkyltin chlorides readily proceeds via the methylene carbon with the formation of C-substituted products Me_3-n(t-BuO)_nSiCH₂SnR₃, R = Me, n-Bu in high yields. The path of this reaction with Me₃SiCl and MePh₂SiCl depends on the structure of Grignard compound and chlorosilane electrophilicity. Increasing the number of the tert-butoxy groups in the Grignard reagent has unexpectedly been found to result in the formation of Me_3-n(t-BuO)_nSiCH₂OSiMeR₂, R = Me, Ph and decrease of the organosilylmethyl silicon compounds content in the reaction products. The structure of the compounds synthesized has been confirmed by ¹H, ¹³C, ²⁹Si, ^117,119Sn NMR spectroscopy and mass spectrometry.

Full text of DOI:10.1016/j.ica.2020.119555

InorganicaChimicaActa507(2020)119555
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
The reaction of (tert-Butoxysilyl)methylmagnesium chlorides with some
organotin and organosilicon monochlorides
Evgeny A. Monin⁎, Irina A. Bykova, Valentina M. Nosova, Alexander V. Kisin,
Alexander M. Philippov, Pavel A. Storozhenko
State Research Institute for Chemistry and Technology of Organoelement Compounds (SSC RF GNIIChTEOS), 38, Shosse Entuziastov, Moscow 105118, Russian Federation
A R T I C L E I N F O
A B S T R A C T
Keywords:
Interaction between (tert-butoxysilyl)methylmagnesium chlorides of the general formula Me3-n(t-
BuO)nSiCH2MgCl, n = 1–3, with some organotin and organosilicon monochlorides has been studied. It has been
found that the reaction of the Grignard reagents with trialkyltin chlorides readily proceeds via the methylene
carbon with the formation of C-substituted products Me3-n(t-BuO)nSiCH2SnR3, R = Me, n-Bu in high yields. The
path of this reaction with Me3SiCl and MePh2SiCl depends on the structure of Grignard compound and chlor-
osilane electrophilicity. Increasing the number of the tert-butoxy groups in the Grignard reagent has un-
expectedly been found to result in the formation of Me3-n(t-BuO)nSiCH2OSiMeR2, R = Me, Ph and decrease of
the organosilylmethyl silicon compounds content in the reaction products. The structure of the compounds
synthesized has been confirmed by 1H, 13C, 29Si, 117,119Sn NMR spectroscopy and mass spectrometry.
Grignard reagents
Organosilylmethyl silicon compounds
Organosilylmethyl tin compounds
NMR spectroscopy
Mass spectrometry
1. Introduction
substituents bonded to the silicon were used by Corriu et al. in this reaction
[11,12]. Recently those containing isopropoxy groups at silicon have been
Organosilylmethyl containing organoelement compounds with al-
koxy substituents bonded to the silicon are capable of polymerization
and can be used for the production of branched polysiloxanes with
organoelement substituents in the side chain.
employed for the synthesis of isopropoxysilylmethyl tin substances [13,14].
It should be noted that the application of Grignard reagents with the
general formula Me3-n(AlkO)nSiCH2MgCl, Alk = Me, Et or i-Pr is often
limited by their low stability due to interaction with alkoxysilicon
moieties [15,16].
Organosilylmethyl tin derivatives are distinguished by good surface ad-
hesion, stability toward UV irradiation and high humidity, and high biolo-
gical activity exhibited in the majority of cases. The latter feature suggests
their use as plant protection agents in agriculture and as components of
special paints and compositions for treating vessels against biofouling [1,2],
fungicides and insecticides to protect and enhance the biostability of various
materials such as wood, stone, textile, paper, and leather [3].
Previously, we have reported on the synthesis of tert-butoxy substituted
silylmethylmagnesium chlorides 3a-c with the general formula Me3-n(t-
BuO)nSiCH2MgCl, n = 1–3, from the suitable chloromethylchlorosilanes
1a-c via tert-butoxy substituted chloromethylsilanes 2a-c (Scheme 1). The
yields of compounds 3a-c amounted to 90–95%. These substances were
found to be stable in THF at room temperature [17,18] and their stability
increased with the increasing of the number of tert-butoxy groups.
The reaction of these tert-butoxy substituted Grignard compounds
with group IVa electrophiles has not been studied yet.
In turn, alkoxysilylmethyl organosilicon derivatives are precursors
of thermostable organosilicon polymers used in microelectronics for the
creation of durable, non-cracking, chemically resistant films with high
dielectric properties [4–7].
The purpose of the present work is the investigation of the reaction
of synthesized (tert-butoxysilyl)methylmagnesium chlorides with some
organotin and organosilicon monochlorides. Our attention was in par-
ticular focused on studying the reactivity of these reagents depending
on the number of tert-butoxy groups bonded to the silicon and the
nature of an organoelement electrophile. It was also interesting to
elucidate certain structural features and spectral characteristics of these
new (tert-butoxysilyl)methyl organoelement compounds.
In this connection, new alkoxysilylmethyl organosilicon compounds
are of considerable practical interest.
The reaction of silylmethylmagnesium chlorides with various organotin
and organosilicon monochlorides is a convenient method for the synthesis
of such compounds. (Trialkylsilyl)methylmagnesium chlorides have been
used in the synthesis of methylenedisilicon containing compounds since the
1940s [8–10]. Later, such Grignard compounds with ethoxy and isopropoxy
⁎ Corresponding author.
E-mail address: monin@eos.su (E.A. Monin).
https://doi.org/10.1016/j.ica.2020.119555
Received 18 October 2019; Received in revised form 25 February 2020; Accepted 26 February 2020
Availableonline27February2020
0020-1693/©2020ElsevierB.V.Allrightsreserved.

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
Mg, THF
n t-BuOK, THF
Me3-n(t-BuO)nSiCH2MgCl
3a-c
Me3-n(t-BuO)nSiCH2Cl
Me3-nClnSiCH2Cl
1a-c
- n KCl
2a-c
n=1 (a); n=2 (b); n=3 (c)
Scheme 1.
1
1
2. Experimental
monoresonance
δ
−0.7 (s, 1C, SiMe, JCH
=
119.3 q, JCSi
3
1
= 78.5, JCH = 0.8 t); 30.78 (s, CH235Cl (75%), JCH = 136.7
1
3
2.1. Material and methods
q, JCSi = 79.8, JCH = 1.0 q); 30.77 (s, CH237Cl (25%)); 31.9 (s,
6C, Me3CO); 73.2 (s, 2C, Me3CO); 29Si δ −29.0 (s).
All glassware was heated at 100–120 °C in vacuum before use. All
manipulations were carried out in dry solvents under dry argon. THF was
boiled under argon until the formation of the deep blue color of benzo-
phenone ketyl and distilled immediately before the experiment. Hexane was
dried and distilled under phosphorus pentoxide. Potassium tert-butylate, a
product of Acros Organics, was utilized without additional purification.
The 1H (600.0 MHz), 13C (150.9 MHz), 29Si (119.2 MHz), 119Sn
(223.8 MHz), and 117Sn (213.8 MHz) NMR spectra were recorded on a
Bruker AVANCE 600 spectrometer at 30 °C. The proton chemical shifts (δ,
ppm) were measured relative to the residual C6HD5 (δ 7.155 for solutions in
C6D6) or CHCl3 (δ 7.248 for solutions in CDCl3). The 13C chemical shifts
were measured relative to C6D6 (δ 128.02) or CDCl3 (δ 77.00). The 29Si
chemical shifts were measured relative to external TMS in C6D6 or CDCl3.
The 119Sn and 117Sn chemical shifts were measured relative to external
Me4Sn in C6D6. The HSQC (1H–13C) and HSQC (1H-29Si) spectra were re-
corded for assignment of 1H, 13C and 29Si NMR signals [19,20]. Spectra
processing was performed with Bruker’s TopSpin software package. The
2.2.3. [Tri(tert-butoxy)silyl]methyl chloride (2c)
20
20
Colorless liquid, yield 59%, b.p. 81–82 °C (5 torr), d4 1.3210, nD
1.4200. NMR (C6D6): 1H δ 1.31 (s, 27H, Me3CO); 2.61 (s, 2H, CH2Cl); 13
C
{1H} δ 28.8 (s, 1C, CH2Cl, 1JCSi = 107.8), 31.6 (s, 9C, Me3CO), 73.2 (s, 3C,
Me3CO); 29Si{1H} and monoresonance δ −72.5 (s, JSiC = 107.6,
1
2JSiH = 5.3 t).
2.3. Synthesis of (tert-butoxysilyl)methylmagnesium chlorides 3a-c
2.3.1. [Dimethyl(tert-butoxy)silyl]methylmagnesium chloride (3a)
A solution of 25.0 mmol (4.52 g) of [dimethyl(tert-butoxy)silyl]
methyl chloride 2a in 50 ml of THF was added to 25.0 mmol (0.6 g) of
magnesium preliminary activated with iodine in 20 ml of THF at 50 °C.
After the mixture began to boil, the further process was carried out
without additional heating. The chloromethylsilane was added over
1.0 h then the reaction mixture was boiled for 0.5 h until complete
magnesium dissolving. The yield of the Grignard reagent 3a according
to titration by 0.1 N HCl was better than 98%.
1JCH
,
3JCH (Hz) values and the multiplicities of the signals were obtained
from the monoresonance 13C spectra. Only chemical shifts are given for t-
BuO-groups in the 13C NMR, since 1JCH and 3JCH for all these groups are the
1
1
same: 125.3 ÷ 125.5 and 4.0 ÷ 4.1 Hz, respectively. The JCSi and JCSn
2.3.2. [Methyldi(tert-butoxy)silyl]methylmagnesium chloride (3b)
A solution of 25.0 mmol (5.96 g) of [methyldi(tert-butoxy)silyl]
methyl chloride 2b in 50 ml of THF was added to 25.0 mmol (0.6 g) of
magnesium preliminary activated with iodine in 20 ml of boiling THF.
The chloromethylsilane was added over 1.0 h then the reaction mixture
were obtained from the doublet signals of the 29Si, 119Sn and 117Sn satellites
in the 13C{1H} NMR spectra. Likewise, the JSiC and JSiSn were obtained
1
2
from the doublet signals of 13C, 119Sn and 117Sn satellites in the 29Si{1H}
n
2
NMR spectra. At last, the JSnC and JSnSi were obtained from the doublet
signals of 13C and 29Si satellites in the 119Sn{1H} NMR spectra.
The mass spectra were obtained on the Agilent 240 Ion Trap GC/MS
was boiled for 1.5–2
h until complete magnesium dissolving.
Determined as above, the yield of the product 3b was 95–96.5%.
system.
A
VF-5
ms
quartz
capillary
column
(30 m × 0.25 mm × 0.25 µm) was used for reaction mixture separa-
tion. The volume of the probe was 1 μL and evaporator temperature was
set at 300 °C. Set initially at 120 °C, the temperature of the column was
raised in 1 h to 300 °C at a rate of 20 °C/min and then kept constant for
25 min. Helium was supplied at a flow rate of 1 ml/min; the stream was
divided in the evaporator in the ratio 30:1.
2.3.3. [Tri(tert-butoxy)silyl]methylmagnesium chloride (3c)
A solution of 25.0 mmol (7.41 g) of [tri(tert-butoxy)silyl]methyl
chloride 2c in 50 ml of THF was added to 25.0 mmol (0.6 g) of mag-
nesium preliminary activated with iodine in 20 ml of boiling THF. The
chloromethylsilane was added over 1.0 h then the reaction mixture was
boiled for 3–4 h until complete magnesium dissolving. Determined as
above, the yield of the product 3c was 92–95%.
2.2. Synthesis of tert-butoxy substituted chloromethylsilanes 2a-c
2.4. Synthesis of (tert-butoxysilyl)methyl substituted stannanes 4a-f
Tert-butoxy-substituted chloromethylsilanes 2a-c were synthesized
according to the abovementioned procedure with anhydrous potassium
tert-butylate taken in an amount of 1–3 mol [17].
A solution of 25 mmol (5.0 g) of trimethyltin chloride or 25 mmol
(8.14 g) of tri(n-butyl)tin chloride in a fourfold volume of THF was
added dropwise to a filtered solution of 25 mmol of one of the Grignard
reagents 3a-c in THF at room temperature during 0.5 h.
2.2.1. [Dimethyl(tert-butoxy)silyl]methyl chloride (2a)
30
30
Colorless liquid, yield 61%, b.p. 70–71 °C (28 torr), d4 1.4517, nD
The temperature of the reaction mixture rose to 30–32 °C. Stirred for
1 h, the reaction mixture was then left overnight. Next day, THF was
distilled off at 300 torr on a bath at 70 °C. The residue was twice ex-
tracted by a threefold volume of hexane. The precipitated residue was
filtered off and washed with hexane. The hexane was removed from the
combined extracts and the residue was distilled in vacuum.
1.4162. NMR (C6D6): 1H δ 0.16 (s, 6H, SiMe2, 1JHC = 119.2, 2JHSi = 6.9);
1
1
1.11 (s, 9H, Me3CO, JHC = 125.3); 2.58 (s, 2H, CH2Cl, JHC = 137.0);
13C{1H} and monoresonance δ −0.68 (s, 2C, SiMe2, JCH = 119.2 q,
1
1JCSi = 62.4, JCH = 1.4 m, 6 lines); 31.197 (s, CH235Cl (75%),
3
1
3
1JCH = 136.6 t, JCSi = 62.1, JCH = 1.9 m, 7 lines); 31.189 (s, CH237Cl
(25%)); 32.0 (s, 3C, Me3CO); 72.8 (s, 1C, Me3CO); 29Siδ 2.4 (s,
1JSiC = 62.2).
2.4.1. [[Dimethyl(tert-butoxy)silyl]methyl]trimethylstannane (4a)
Colorless liquid, yield 4.71 g (61%), b.p. 82–84 °C (3 torr), d420 1.5822,
nD20 1.5205. NMR (C6D6): 1H δ −0.17 (s, 2H, CH2, 1JHC = 117.4, 2JHSn(119/
117) = 72.3/69.1, 2JHSi = 6.6); 0.175 (s, 6H, SiMe2, 1JHC = 117.7); 0.177
2.2.2. [Methyldi(tert-butoxy)silyl]methyl chloride (2b)
20
23
Colorless liquid, yield 51%, b.p. 67–70 °C (1 torr), d4 1.4897, nd
1.4143. NMR (C6D6): 1H δ 0.29 (s, 3H, SiMe, 1JHC = 119.2, 2JHSi = 7.3);
(s, 9H, SnMe3, JHC = 127.8, JHSn(119/117) = 53.9/51.5); 1.20 (s, 9H,
1
2
1
1
1.23 (s, 18H, Me3CO); 2.62 (s, 2H, CH2Cl, JHC = 136.5); 13C{1H} and
Me3CO); 13C{1H} and monoresonance δ −7.9 (s, 3C, SnMe3, JCSn(119/117/
2

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
1
1
= 334.5/319.7/293.5, JCH = 127.7 q); −1.5 (s, 1C, CH2, JCSn(119/
2C, Me3CO); 29Si{1H} δ −16.8 (s, 2JSiSn(119/117) = 26.5/25.3); 119Sn{1H} δ
115)
117)
1
1
1
1
2
= 244.7/233.9, JCH = 117.8 t, JCSi = 60.8); 4.2 (s, 2C, SiMe2,
−4.2 (s, JSnCH2CH2CH2CH3 = 329.5, JSnCH2Si = 190.5, JSnSi = 26.3,
1JCH = 117.7 q, 1JCSi = 57.4, 3JCSn ≈ 11); 32.3 (s, 3C, Me3CO); 72.2 (s, 1C,
2JSnCH2CH2CH2CH3 = 19.9, JSnCH2CH2CH2CH3 = 58.6).
3
Me3CO); 29Si{1H} δ 8.3 (s, JSiCH2 = 60.9, JSiCH3 = 57.4, JSiSn(119/
117) = 27.8/26.6); 119Sn{1H} δ 4.9 (s, 1JSnCH3 = 335.1, 1JSnCH2Si = 245.5,
2JSnSi = 27.6). Elemental analysis for C10H26OSiSn calculated (%): C, 38.85;
H, 8.48. Found (%): C, 38.78; H, 8.40.
1
1
2
2.4.6. [[Tri(tert-butoxy)silyl]methyl]tri(n-butyl)stannane (4f)
Colorless liquid, yield 11.0 g (80.0%), b.p 140–145 °C (1 × 10−3 torr),
24
24
d4 1.5337, nd 1.4630. NMR (C6D6): 1H δ −0.14 (s, 2H, SiCH2,
2
2
1JHC = 117.4, JHSn(119/117/115) = 66.3/63.4/58.3, JHSi = 7.9); 0.97 (t,
2.4.2. [[Methyldi(tert-butoxy)silyl]methyl]trimethylstannane (4b)
9H, CH2CH2CH2CH3, 3JHH = 7.3); 1.08 (m, 6H, CH2CH2CH2CH3, 2JHSn(119/
25
Colorless liquid, yield 5.69 g (62.0%), b.p. 104–105 °C (1 torr), d4
=
52.1/49.8); 1.37 (s, 27H, Me3CO); 1.43 (m,
6
lines, 6H,
117)
1.5303, nd
1.4720. NMR (C6D6): 1H
δ
2
−0.15 (s, 2H, CH2,
CH2CH2CH2CH3, JHH = 7.3); 1.65 (m, 6H, CH2CH2CH2CH3); 13C{1H} δ
25
3
2
1JHC = 117.8, JHSn(119/117) = 72.1/69.2, JHSi = 6.7); 0.20 (s, 3H,
−6.2 (s, 1C, SiCH2, 1JCSn(119/117) = 193.3/184.7, 1JCSi = 98.1); 10.8 (s, 3C,
1
2
1
1
SiMe, JHC = 117.7, JHSi = 6.9); 0.22 (s, 9H, SnMe3, JHC = 127.8,
CH2CH2CH2CH3, JCSn(119/117/115) = 330.3/316.1/290.0); 14.0 (s, 3C,
2JHSn(119/117) = 54.3/51.8); 1.28 (s, 9H, Me3CO); 13C{1H} and mono-
CH2CH2CH2CH3); 27.9 (s, 3H, CH2CH2CH2CH3, 3JCSn(119/117) = 58.8/56.1);
1
2
resonance
δ
−7.8 (s, 3C, SnMe3, JCSn(119/117)
=
337.6/322.0,
29.7 (s, 3C, CH2CH2CH2CH3, JCSn(119/117) = 19.7/19.0); 32.0 (s, 9C,
1JHC = 127.8 q); −1.1 (s, 1C, CH2, JCSn(119/117) = 239.0/228.5,
Me3CO); 72.5 (s, 3C, Me3CO); 29Si{1H} δ −57.0 (s, 1JSiC = 98.2, 2JSiSn(119/
1
1JCH = 117.9 t, JCSi = 74.3); 4.7 (s, 1C, SiMe, JCH = 117.7 q,
= 32.1/30.7); 119Sn{1H} δ −3.1 (s, JSnCH2CH2CH2CH3 = 330.6,
1
1
1
117)
1JCSi = 70.6, JCSn = 6.0); 32.3 (s, 6C, Me3CO); 72.7 (s, 2C, Me3CO);
1JSnCH2Si
=
193.3, JSnSi
=
32.1, JSnCH2CH2CH2CH3
=
19.8,
3
2
2
29Si{1H} δ −17.5 (s, JSiCH2 = 74.4, JSiCH3 = 70.7, JSiSn(119/
3JSnCH2CH2CH2CH3 = 58.8).
1
1
2
1
=
30.2/28.8); 119Sn{1H}
δ
2.2 (s, JSnCH3
=
337.6,
117)
1JSnCH2Si = 238.6, 2JSnSi = 30.2). Elemental analysis for C13H32O2SiSn
2.5. (tert-Butoxysilyl)methyl substituted silanes 5a-f
calculated (%): C, 42.52; H, 8.78. Found (%): C, 42.39; H, 8.71.
The reaction was carried out according to the method described
above for compounds 4a-f using a solution of 25 mmol of one of the
Grignard reagents 3a-c in THF and 25 mmol (2.7 g) of trimethylsilicon
chloride or 25 mmol (5.8 g) of methyldiphenylsilicon chloride. The
reaction mixture was stirred at reflux for 1–6 h in the case of tri-
methylsilicon chloride and for 1–2 h when methyldiphenylsilicon
chloride was taken and then left overnight. The reactions were mon-
itored by NMR spectroscopy until the complete disappearance of the
CH2MgCl-proton signals of 3a-c. The reaction proceeds with the for-
mation of a complex mixture of products 5a-f, 6a-f, 7a-c and 8 (part
3.4). Substances 5a,d were isolated by distillation in vacuum.
The 1H NMR data obtained for tert-butoxysilylmethyl substituted
silanes 5a-e are presented in part 3.2.2.
2.4.3. [[Tri(tert-butoxy)silyl]methyl]trimethylstannane (4c)
Colorless liquid, yield 6.38 g (60.0%), b.p. 87 °C (0.1 torr), d425 1.5166,
nd25 1.4445. NMR (C6D6): 1H δ −0.14 (s, 2H, CH2, 1JHC = 118.1, 2JHSn(119/
117) = 72.0/68.9, 2JHSi = 7.8); 0.29 (s, 9H, SnMe3, 1JHC = 128.0, 2JHSn(119/
= 54.6/52.2); 1.35 (s, 27H, Me3CO); 13C{1H} and monoresonance δ
117)
1
1
−7.7 (s, 3C, SnMe3, JCSn(119/117) = 337.8/323.1, JCH = 127.8 q); −3.0
1
1
1
(s, 1C, CH2, JCSn(119/117) = 242.2/231.3, JCH = 118.0 t, JCSi = 97.8);
32.0 (s, 9C, Me3CO); 72.4 (s, 3C, Me3CO); 29Si{1H} δ −57.7 (s, JSiSn(119/
2
117) = 37.1/35.5); 119Sn{1H} δ 3.8 (s, 1JSnCH3 = 337.8, 1JSnCH2Si = 242.2,
2JSnSi = 37.1). Elemental analysis for C16H38O3SiSn calculated (%): C,
45.19; H, 9.00. Found (%): C, 45.36; H, 8.87.
2.4.4. [[Dimethyl(tert-butoxy)silyl]methyl]tri(n-butyl)stannane (4d)
20
Colorless liquid, yield 9.0 g (83.0%), b.p. 83–85 °C (4 × 10−4 torr), d4
2.5.1. [[Dimethyl(tert-butoxy)silyl]methyl]trimethylsilane (5a)
1.5276, nd20 1.4745. NMR (C6D6): 1H δ −0.13 (s, 2H, SiCH2, 1JHC = 117.0,
Colorless liquid, yield 2.13 g (39.0%), b.p 74–75 °C (14 torr), nd
22
2JHSn (119/117) = 66.8/64.0, 2JHSi = 6.6); 0.23 (s, 6H, SiMe2, 1JHC = 117.7,
1.4187. NMR (C6D6): 13C{1H} and monoresonance δ 1.5 (s, 3C, SiMe3,
3
1
3
3
2JHSi = 6.5); 0.95 (t, 9H, CH2CH2CH2CH3, JHH = 7.3); 0.98 (m, 6H,
1JCH = 118.4 q, JCSi = 50.9, JCH = 2.1 m, 9 lines); 4.3 (s, 2C, SiMe2,
1
CH2CH2CH2CH3, 2JHSn(119/117) = 51.1/49.0); 1.23 (s, 9H, Me3CO); 1.40 (m,
1JCH = 117.7 q, JCSi = 57.4, JCH = 1.6 m, 6 lines); 7.1 (s, 1C, CH2,
1JCH = 108.6 t, 1JCSi = 56.4, 1JCSi = 44.3, 3JCH = 1.6 m, 16 lines, only 10
visible); 32.3 (s, 3C, Me3CO); 72.2 (s, 1C, Me3CO); 29Si{1H} and mono-
6 lines, 6H, CH2CH2CH2CH3, 3JHH = 7.4); 1.59 (m, 6H, CH2CH2CH2CH3);
1
13C{1H} and monoresonance δ −4.5 (s, 1C, SiCH2, JCSn(119/117) = 196.5/
1
1
1
1
1
2
187.6, JCH = 117.2 t, JCSi = 61.6); 4.5 (s, 2C, SiMe2, JCH = 117.6 q,
resonance δ −0.3 (s, SiMe3, JSiC = 50.8, JSiC = 44.2, JSiCH2 = 8.8 t,
1JCSi = 57.1, JCSn = 9.9, JCH = 1.7 m, 6 lines); 10.7 (s, 3C,
2JSiCH3 = 6.7 m, 10 lines, only 6 visible); 6.6 (s, SiMe2, JSiC = 57.1,
3
3
1
CH2CH2CH2CH3, 1JCSn(119/117) = 327.3/312.7, 1JCH = 126.5 t); 14.0 (s, 3C,
2JSiCH2 = 8.7 t, 2JSiCH3 = 6.6 m, 7 lines). Elemental analysis for C10H26OSi2
1
3
CH2CH2CH2CH3, JCH = 124.5); 27.9 (s, 3C, CH2CH2CH2CH3, JCSn(119/
calculated (%): C, 54.97; H, 12.00. Found (%): C, 54.82; H, 11.93.
2
= 58.0/55.4); 29.7 (s, 3C, CH2CH2CH2CH3, JCSn(119/117) = 19.8/
117)
19.0); 32.3 (s, 3C, Me3CO); 72.2 (s, 1C, Me3CO); 29Si{1H} δ 8.8 (s,
2.5.2. [[Methyldi(tert-butoxy)silyl]methyl]trimethylsilane (5b)
1JSiCH2 = 61.4, JSiCH3 = 57.2, JSiSn(119/117) = 24.9/23.9); 119Sn{1H} δ
NMR (C6D6): 13C{1H} and monoresonance δ 1.4 (s, 3C, SiMe3,
1JCH = 118.4 q, 1JCSi = 51.1, 3JCH = 2.1 m, 9 lines, only 7 visible); 4.9
1
2
1
1
2
−2.4 (s, JSnCH2CH2CH2CH3 = 327.3, JSnCH2Si = 196.2, JSnSi = 25.0,
3
1
1
3
2JSnCH2CH2CH2CH3 = 20.0, JSnCH2CH2CH2CH3 = 58.0).
(s, 1C, SiMe, JCH = 117.6 q, JCSi = 70.6, JCH = 0.9 t); 7.7 (s, 1C,
1 1 1
CH2, JCH = 108.7 t, JCSi = 68.9, JCSi = 43.5); 32.2 (s, 6C, Me3CO);
72.3 (s, 2C, Me3CO); 29Si{1H} δ −19.9 (s, SiMe), −0.6 (s, SiMe3).
2.4.5. [[Methyldi(tert-butoxy)silyl]methyl]tri(n-butyl)stannane (4e)
Colorless liquid, yield 10.85 g (88.0%), b.p. 103–105 °C (1×10−3 torr),
d4 1.5020, nd 1.4655. NMR (C6D6): 1H δ −0.13 (s, 2H, SiCH2,
2.5.3. [[Tri(tert-butoxy)silyl]methyl]trimethylsilane (5c)
20
20
1JHC = 117.3, JHSn(119/117) = 66.5/64.4, JHSi = 6.5); 0.25 (s, 3H, SiMe,
1JHC = 117.6, 2JHSi = 6.7); 0.96 (t, 9H, CH2CH2CH2CH3, 3JHH = 7.3); 1.02
(m, 6H, CH2CH2CH2CH3); 1.31 (s, 18H, Me3CO); 1.41 (m, 6 lines, 6H,
CH2CH2CH2CH3, 3JHH = 7.4); 1.62 (m, 6H, CH2CH2CH2CH3); 13C{1H} and
NMR (CDCl3): 13C{1H} and monoresonance δ 1.1 (s, 3C, SiMe3,
1JCH = 118.6 q, 1JCSi = 51.3, 3JCH = 2.0 m, 9 lines, only 7 visible); 5.8
2
2
1
1
1
3
(s, 1C, CH2, JCH = 108.7 t, JCSi = 90.7, JCSi = 43.6, JCH = 1.8 m,
10 lines, only 8 visible); 31.7 (s, 9C, Me3CO); 72.6 (s, 3C, Me3CO); 29Si
{1H} and monoresonance δ −61.2 (s, t-BuOSi, 2JSiCH2 = 10.4 t); −0.4
1
monoresonance δ −4.2 (s, 1C, SiCH2, JCSn(119/117) = 190.4/181.9,
2
2
1JCH = 117.4 t, 1JCSi = 75.0); 4.9 (s, C, SiMe, 1JCH = 117.5 q, 1JCSi = 70.4,
(s, SiMe3, JSiCH2 = 8.7 t, JSiCH3 = 6.6 m, 10 lines, only 8 visible).
1
3JCSn = 5.3); 10.8 (s, 3C, CH2CH2CH2CH3, JCSn(119/117/115) = 329.5/
315.0/289.3, 1JCH = 126.4 t); 14.0 (s, 3C, CH2CH2CH2CH3, 1JCH = 124.4);
2.5.4. [[Dimethyl(tert-butoxy)silyl]methyl]methyldiphenylsilane (5d-I and
5d-II)
3
27.9 (s, 3C, CH2CH2CH2CH3, JCSn(119/117) = 58.4/55.8); 29.7 (s, 3C,
CH2CH2CH2CH3, 2JCSn(119/117) = 19.7/19.0); 32.2 (s, 6C, Me3CO); 72.3 (s,
The signals of two spatial rotational isomers are observed in the
3

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
spectra: 5d-I and 5d-II in the integral intensity ratio 13:1. Colorless
liquid, yield 5.16 g (60.3%), b.p. 120–125 °C (1.2 × 10−2 torr).
5d-I NMR (C6D6): 13C{1H} and monoresonance δ −1.5 (s, 1C,
SiMePh2, 1JCH = 119.9 q, 1JCSi = 54.1, 3JCH = 2.4 t); 4.34 (s, 1C, CH2,
1JCH = 109.3 t, 1JCSi = 55.6, 1JCSi = 47.2, 3JCH = 1.5 m, 10 lines, only
(10.0%), b.p 120–124 °C (2,5x10-5 torr). NMR (C6D6): 13C{1H} and mono-
resonance δ −0.1 (s, 1C, SiMe, 1JCH = 118.7 q, 1JCSi = 74.3, 3JCH = 0.8 t);
−3.2 (s, 1C, SiMePh2, 1JCH = 119.5 q, 1JCSi = 62.0); 32.11 (s, 6C, Me3CO);
1
1
56.5 (s, 1C, CH2O, JCH = 129.9 t, JCSi = 89.4); 72.7 (s, 2C, Me3CO);
128.1 (s, 4C, m-Ph); 129.9 (s, 2C, p-Ph); 134.9 (s, 4C, o-Ph); 136.8 (s, 2C, i-
Ph); 29Si{1H} δ −25.9 (s, t-BuOSi); −0.9 (s, SiMePh2).
1
1
8
visible); 4.37 (s, 2C, SiMe2, JCH
=
117.9 q, JCSi
=
57.8,
3JCH = 1.6 m, 6 lines); 32.1 (s, 3C, Me3CO); 72.4 (s, 1C, Me3CO); 127.9
(s, 4C, m-Ph); 129.1 (s, 2C, p-Ph); 134.8 (s, 4C, o-Ph); 139.6 (s, 2C, i-Ph,
2.6.6. [[Tri(tert-butoxy)silyl]methoxy]methyldiphenylsilane (6f)
Colorless viscous liquid, the yield after distillation in vacuum is
2.13 g (18.0%), b.p 103–105 °C (4.5x10-5 torr). NMR (C6D6): 13C{1H} δ
1JC(ipso)Si = 67.4); 29Si{1H} δ −8.1 (s, SiMePh2, JSiC(ipso) = 67.3,
1
1JSiC = 54.1, 1JSiC = 47.0); 6.8 (s, t-BuOSi, 1JSiC = 57.8, 1JSiC = 55.8).
5d-II NMR (C6D6): 13C{1H} and monoresonance δ −1.6 (s, 1C,
SiMePh2, 1JCH = 119.8 q, 1JCSi = 53.8, 3JCH = 2.5 t); 3.5 (s, 2C, SiMe2,
1JCH = 118.1 q, 1JCSi = 59.6, 3JCH = 1.6 m, 6 lines); 4.31 (s, 1C, CH2);
32.2 (s, 3C, Me3CO); 73.4 (s, 1C, Me3CO); 127.6–139.6 (s, 12C, Ph); 29Si
1
−3.1 (s, 1C, SiMePh2, JCSi = 62.6); 32.0 (s, 9C, Me3CO); 55.0 (s, 1C,
1
CH2O, JCSi = 116.3); 72.9 (s, 3C, Me3CO); 128.1 (s, 4C, m-Ph); 129.9
(s, 2C, p-Ph); 135.0 (s, 4C, o-Ph); 136.9 (s, 2C, i-Ph); 29Si{1H} δ −69.7
(s, t-BuOSi); −1.8 (s, SiMePh2).
{1H} δ −8.7 (s, SiMePh2); 6.9 (s, t-BuOSi, JSiC = 59.5).
1
2.7. tert-Butoxy substituted methylsilanes 7a-c
2.5.5. [[Methyldi(tert-butoxy)silyl]methyl]methyldiphenylsilane (5e)
NMR (C6D6): 13C{1H} and monoresonance δ −1.6 (s, 1C, SiMePh2,
2.7.1. Trimethyl(tert-butoxy)silane (7a)
1JCH = 120.0 q, JCSi = 54.6, JCH = 2.4 t); 4.7 (s, 1C, SiMe,
The substance was detected by 29Si NMR only. The 1H and 13C
signals could not be detected due to the high-intensity signals of other
substances. NMR (C6D6): 29Si {1H} and monoresonance δ 6.8 (s,
2JSiCH3 = 6.4 m, 10 lines, 6 visible). Literature data: 1H δ 0.05 (s, 9H,
SiMe3); 1.23 (s, 9H, Me3CO); 13C{1H} δ 1.4 (s, 3C, SiMe3); 31.1 (s, 3C,
Me3CO); 71.9 (s, 1C, Me3CO) [21–25]; 29Si 6.2 [23,25].
1
1
3
3
1JCH = 118.0 q, JCSi = 71.6, JCH = 1.0 t); 5.1 (s, 1C, CH2,
1JCH = 109.2 t, JCSi = 67.6); 32.06 (s, 6C, Me3CO); 72.5 (s, 2C,
1
Me3CO); 127.9 (s, 4C, m-Ph); 129.0 (s, 2C, p-Ph); 134.8 (s, 4C, o-Ph);
139.7 (s, 2C, i-Ph); 29Si{1H} δ −20.5 (s, t-BuOSi); −8.3 (s, SiMePh2).
2.5.6. [[Tri(tert-butoxy)silyl]methyl]methyldiphenylsilane (5f)
NMR (C6D6): the 1H and 13C signals are not visible due to their over-
lapping with other signals; 29Si{1H} δ −64.7 (s, t-BuOSi), −7.4 (s, SiMePh2).
2.7.2. Dimethyldi(tert-butoxy)silane (7b)
B.p. 57 °C (30 torr). NMR (C6D6): 1H
δ 0.20 (s, 6H, SiMe2,
1JHC = 117.6); 1.28 (s, 18H, Me3CO); 13C{1H} and monoresonance δ 3.1 (s,
1
1
3
2.6. (tert-Butoxysilyl)methoxy substituted silanes 6a-f
2C, SiMe2, JCH = 117.8 q, JCSi = 72.9, JCH = 1.0 q); 32.1 (s, 6C,
Me3CO); 72.2 (s, 2C, Me3CO); 29Si{1H} δ −18.8 (lit. data δ −19.9 [23]).
(tert-Butoxysilyl)methoxy substituted silanes 6a-f were prepared
according to the procedure described above in admixture with com-
pounds 5a-f. Substances 6c,e,f were isolated in pure form. The 1H NMR
data (C6D6; δ, ppm; J, Hz) obtained for 6a-f are presented in part 3.2.2.
2.7.3. Methyltri(tert-butoxy)silane (7c)
25
B.p. 75 °C (10 torr), nd231.3965 (B.p. 90–91 °C (20 torr), nd 1.3959,
d4 0.8493 [26], 192–5 °C, nd 1.3972 [15]. NMR (C6D6): 1H δ 0.25 (s,
3H, SiMe, 1JHC = 118.2, 2JHSi = 8.3); 1.35 (s, 18H, Me3CO); 13C{1H} and
monoresonance δ 1.8 (s, 1C, SiMe, 1JCH = 118.3 q, 1JCSi = 96.2); 31.9 (s,
9C, Me3CO); 72.3 (s, 3C, Me3CO); 29Si{1H} δ −59.0.
25
21
2.6.1. [[Dimethyl(tert-butoxy)silyl]methoxy]trimethylsilane (6a)
NMR (C6D6): 13C{1H} and monoresonance δ −0.7 (s, 3C, OSiMe3,
1JCH = 118.1 q, JCSi = 58.9, JCH = 1.6 m, 7 lines); −0.6 (s, 2C,
SiMe2, 1JCH = 118.6 q, 1JCSi = 59.8, 3JCH = 1.4 m, 6 lines); 32.2 (s, 3C,
Me3CO); 55.8 (s, 1C, CH2O, 1JCH = 129.2 t, 1JCSi = 72.3, 3JCH = 1.6 m,
The NMR spectra obtained for compounds 7a-c correspond to those
predicted on the basis of calculation using Advanced Chemistry
Development, Inc. (ACD/Labs) Software V11.01 (© 1994–2019 ACD/Labs).
1
3
7 lines); 72.3 (s, 1C, Me3CO); 29Si{1H} δ 3.1 (s, SiMe2, JSiC = 60.1);
1
1
18.34 (s, OSiMe3, JSiC = 59.1).
2.8. THF cycle cleavage product 8
2.6.2. [[Methyldi(tert-butoxy)silyl]methoxy]trimethylsilane (6b)
NMR (C6D6): 13C{1H} and monoresonance δ −0.7 (s, 3C, OSiMe3,
1JCH = 118.1 q, 1JCSi = 58.8, 3JCH = 1.6 m, 7 lines); −0.3 (s, 1C, SiMe,
2.8.1. Trimethyl(4-iodobutoxy)silane (8)
The content of this compound in the reaction mixture amounts to 3
or 10% in the case of the reaction of Me3SiCl with 3a or 3b, respec-
tively. NMR (C6D6): 1H δ 0.03 (s, 9H, OSiMe3, 2JHSi = 6.3); ≈1.36 (m,
2H, OCH2CH2); 1.60 (m, 2H, ICH2CH2); 2.77 (t, 2H, ICH2, 3JHH = 7.1);
3.32 (t, 2H, OCH2, 3JHH = 6.1); 13C{1H} and monoresonance δ −0.4(s,
3C, OSiMe3, 1JCH = 118.0 q, 3JCH = 1.6 m, 7 lines, 5 visible); 6.3 (s, 1C,
1
3
1JCH = 118.7 q, JCSi = 74.2, JCH = 0.7 t); 32.1 (s, 6C, Me3CO); 55.3
1
1
(s, 1C, CH2O, JCH = 129.3 t, JCSi = 89.8); 72.6 (s, 2C, Me3CO); 29Si
{1H} δ −25.7 (s, SiMe); 18.3 (s, OSiMe3).
2.6.3. [[Tri(tert-butoxy)silyl]methoxy]trimethylsilane (6c)
ICH2, 1JCH = 150.1 t, nJCH = 4.7 m, 5 lines); 30.5 (s, 1C, ICH2CH2, 1JCH
1
Coloress liquid, the yield after distillation in vacuum is 2.6 g (30.0%),
b.p 85–90 °C (50 torr). NMR (CDCl3): 13C{1H} and monoresonance δ −0.9
(s, 3C, OSiMe3, 1JCH = 118.1 q, 1JCSi = 58.8, 3JCH = 1.6 m, 7 lines); 31.7
(s, 9C, Me3CO); 53.2 (s, 1C, CH2O, 1JCH = 128.9 t, 1JCSi = 116.4); 72.5 (s,
≈
126
÷
127 tm); 33.7 (s, 1C, OCH2CH2, JCH
=
126.0 t,
3JCH = 4.1 m, 5 lines, 3JCH = 2.3 t); 61.3 (s, 1C, OCH2, 1JCH = 139.7 t,
nJCH = 4.0 m, 5 lines); 29Si{1H} δ 16.4 (s, OSiMe3).
3C, Me3CO); 29Si{1H} and monoresonance
δ
−69.3 (s, t-BuOSi,
3. Results and discussion
3
1
2JSiCH2 = 5.8 t, JSiCOSi = 7.26); 17.8 (s, OSiMe3, JSiC = 58.8,
2JSiCH3 = 6.6 m, 10 lines, only 8 visible, 3JSiOCSi = 7.25, 3JSiOCH2 = 2.3 t).
3.1. The reaction of (tert-butoxysilyl)methylmagnesium chlorides with
trialkyltin chlorides
2.6.4. [[Dimethyl(tert-butoxy)silyl]methoxy]methyldiphenylsilane (6d)
NMR (C6D6): 13C{1H} δ −1.1 (s, 2C, SiMe2); −0.3 (s, 1C, SiMePh2);
56.6 (s, 1C, CH2O); 127.6 ÷ 138.7 (Ph, signals overlap with product 5d
signals); 29Si{1H} δ −0.8 (s, SiMePh2); 3.0 (s, t-BuOSi).
3.1.1. Synthesis of compounds 4a-f
It has been found, that (tert-butoxysilyl)methylmagnesium chlorides
3a-c readily react with trialkyltin chlorides in THF at room tempera-
ture. The reaction proceeds on the methylene carbon giving C-sub-
stituted products 4a-f (Scheme 2).
2.6.5. [[Methyldi(tert-butoxy)silyl]methoxy]methyldiphenylsilane (6e)
Coloress viscous liquid, the yield after distillation in vacuum is 1.04 g
It should be noted, that the yields of the corresponding C-derivatives
4

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
Me3-n(t-BuO)nSiCH2SnR3 + MgCl2
Me3-n(t-BuO)nSiCH2MgCl + R3SnCl
4a-f
3a-c
R=Me, n=1 (a); n=2 (b); n=3 (c);
R= n-Bu, n=1 (d); n=2 (e); n=3 (f)
Scheme 2.
do not depend on the number of tert-butoxy groups bonded to the si-
licon. At the same time they make up about 60% for methylstannanes
and reach 88% in the case of n-butylstannanes.
In the case of 119Sn NMR spectroscopy, it was found that the signals
of the tin observed as singlets with three pairs of satellites caused by the
interaction of 119Sn with the 29Si nucleus and two different 13C nuclei in
the regions characteristic for tetraalkyl substituted organotin com-
pounds [1,28–31]. The tin chemical shifts for methyl substituted pro-
ducts 4a-c lie in the δ range of 2.2 ÷ 4.9 and shift upfield to δ
−4.2 ÷ −2.4 in the case of n-butyl substituted derivatives 4d-f. The
Compounds 4a-f are stable and may be isolated by vacuum dis-
tillation in up to 88% yields.
3.1.2. NMR spectroscopic analysis of compounds 4a-f
The structures of compounds 4a-f was confirmed by the 1H, 13C,
29Si, 117,119Sn NMR spectra. The assignment of the signals was carried
out by analyzing the spin–spin coupling constants and chemical shifts.
Characteristic doublet signals for the 119Sn and 117Sn magnetic isotopes
with high natural abundances of 8.59 and 7.68%, respectively were
observed in all the 1H, 13C and 29Si NMR spectra of compounds 4a-f. It
was also possible to observe the satellites of the 115Sn isotope with
natural abundance of 0.34% in the 1H and 13C spectra for compounds
4a, 4e and 4f. The assignment of the 1H and 13C signals for n-BuSn-
groups was performed by means of the COSY and HSQC (1H–13C,
J = 127 Hz) spectra.
coupling constants JSnC of the 119Sn with the carbon of the alkyl sub-
1
stituent are in the range of 327.3 ÷ 337.8 Hz, which is fully consistent
with the literature data [1,29].
It is of interest to note that n-Bu3Sn-Sn(n-Bu)3 is also formed in
amounts of up to 3% in the reaction of [(tert-butoxy)silyl]methylmag-
nesium chlorides 3a-c with tri(n-butyl)tin chloride along with the target
products 4d-f. The signal of this distannane is observed in the 119Sn
1
NMR spectrum at δ −83.6. The J(119)Sn-(117)Sn direct constant is
2564.4
0.5 Hz, which is determined from the doublet signals of the
satellites 117Sn of the n-Bu3119Sn-117Sn(n-Bu)3 isotopomer. The same
constant value (1JSn(117)Sn-(119)Sn = 2564.9 0.6 Hz) is observed in the
The NMR data of compounds 4a-f are presented in part 2.4.
Methylene proton signals for compounds 4a-f are observed at δ
−0.17 ÷ −0.13 as singlets with two pairs of satellites due to proton
interaction with 117Sn and 119Sn nuclei, which is typical for such
117Sn NMR spectrum for the signal at δ −83.5. The 1J
(119)Sn-(119)Sn
value calculated according to gyromagnetic ratios is 2683 Hz. Our
1JSnSn data differ from those found in the literature for a distannane
1
1
with n-Bu-groups: J(119)Sn-(117)Sn
=
2625 Hz [32], J(119)Sn-(119)
2
compounds [27]. The JHSn coupling constants lie in the range of
= 2748 Hz (calculated) [1].
Sn
66.3 ÷ 72.3 Hz. The Si substitution pattern of the substances obtained
has insignificant effect on methylene protons chemical shifts and cou-
pling constants, whereas change of SnMe3 to SnBu3 results in a sig-
nificantly lowered coupling constant.
The distannane may be formed in the reaction of tri(n-butyl)tin
chloride with (n-Bu)3SnMgCl [33,34]. The latter could be formed as a
result of the exchange process between Grignard reagent 3c and tri(n-
butyl)tin chloride or from the reaction of residual ultra fine magnesium
and tri(n-butyl)tin chloride.
A methylene carbon signal of compounds 4a-c having methyl
groups bonded to the tin is observed in the 13C{1H} spectra at δ range of
−3.0 ÷ −1.1. The results obtained are in accordance with the known
data [27]. This signal is shifted upfield to δ −6.2 ÷ −4.2 for sterically
hindered substances 4d-f. It is interesting to note that the substituent
3.1.3. Gas chromatographic and mass spectrometric (GC/MS) analysis of
compounds 4a-c
Some of the substances and reaction mixtures were investigated by
GS/MS under electron ionization for an additional confirmation of the
structures of the compounds obtained, wherein fragmentation routes
for main compounds were determined.
1
bonded to the tin has a pronounced effect on the JCSn for SiCH2Sn
1
fragment. The JCSn constants lie in the range of 238.6 ÷ 245.5 Hz in
the case of compounds 4a-c and decrease to 190.5 ÷ 196.2 Hz for n-
butyl substituted derivatives 4d-f.
Compounds
4a-c
with
the
general
formula
Me3-n(t-
The 1JCH constants for methyl and methylene carbons, bonded with
the silicon range from 117.2 to 118.0 Hz. The influence of tin on the
1JCH value is negligible.
BuO)nSiCH2SnMe3, n = 1–3, were analyzed by GC/MS under electron
ionization mode for an additional confirmation of their structures. This
allows obtaining new data on fragmentation for the (tert-butoxysilyl)
methyl tin derivatives.
The 29Si signals of C-substituted compounds 4a-f are located in
the δ range of −57.7 ÷ 8.8 depending on the number of tert-butoxy
groups at silicon. Increasing the number of tert-butoxy groups gives
rise to significant upfield shift of silicon signals due to rising
shielding of silicon which is typical for alkoxysilanes [28]. It should
be noted, however, that the alkyl chain length of the substituents
The fragmentation of substances 4a-c was investigated for the most
intensive 120Sn isotope because of its highest content in nature [35].
It was found that the molecular peaks for all these substances could
not be observed using an Agilent Technologies 240 Ion Trap in the EI
mode with a minimal energy of 70 eV.
2
bonded to the tin has no effect on the 29Si chemical shifts. The JSiSn
For silicon and tin containing products 4a-c splitting off one methyl
group (M = 15) takes place at first giving rise to cations with m/z
[M−15]+. These cations undergo subsequent elimination of isobutene
C4H8 with molecular mass 56 Da. The peaks of maximum intensity with
m/z [M−15−56n]+ (n = 1 ÷ 3) in the mass spectra of compounds 4a-
c prove this fact. It should be noted, that C4H8 fragments release for
compounds 4b with two tert-butoxy groups and for 4c with three tert-
butoxy groups goes step by step with intermediate formation of cations
with m/z 297 for 4b and m/z 355, 299 for 4c, respectively.
values for compounds 4a-f are slightly different and lie in the range
of 27.8 ÷ 37.1 Hz in the case of substances with methyl groups at tin
and in the range of 24.9 ÷ 32.1 Hz in the case of products containing
n-butyl substituents.
At the same time, the 2JSiSn values show a slight but systematic rise
as
the
number
of
tert-butoxy
groups
increases,
i.e.,
27.8 < 30.2 < 37.1 Hz and 24.9 < 26.5 < 32.1 Hz for the series 4a–c
and 4d–f, respectively.
5

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
Table 1
GC/MS data for compounds 4a-c containing the 120Sn isotope.
Compound
M (Da)
τ ret. (min)
m/z (I. % rel.)
4a
4b
4c
310
368
426
5.63
8.01
9.98
295(49) [M-CH3]+; 239(100) [295-C4H8]+; 223 (10); 209(11); 193(12); 165(7); 135(11)
353(49) [M–CH3]+; 297(17) [353-C4H8]+; 241(100) [297- C4H8]+; 223(14); 209(14); 193(18); 165(8); 135(7)
411(50) [M–CH3]+; 355(17) [411-C4H8]+; 299(23) [355-C4H8]+; 243 (100) [299-C4H8]+; 225(13); 195(19); 165(6); 135(6)
GC/MS data for compounds 4a-c with 120Sn isotope are given
(Table 1).
Thus, it was found, that under electron ionization of compounds 4a-
c their stable cations (HO)nMe3-nSiCH2120Sn+Me2 with considerable
signals intensity and m/z 239 (n = 1), 241 (n = 2) and 243 (n = 3)
were formed due to methyl splitting off molecular ions and subsequent
C4H8 elimination from tert-butoxy groups. This is an additional evi-
dence of the compounds 4a-c structure.
Scheme 4.
3.2. The reaction of (tert-butoxysilyl)methylmagnesium chlorides with
chlorosilanes
methyl- and [tri(isopropoxy)silyl]methylmagnesium chlorides with
Me3SiCl, occurring under mild conditions and resulting in the formation
of [(trialkoxysilyl)methyl]trimethylsilanes as the main products with a
yield of up to 82%.
3.2.1. Synthesis of compounds 5-7
Unlike a similar process occurring with organotin compounds, the
reaction of (tert-butoxysilyl)methylmagnesium chlorides 3a-c with
chlorosilanes (Me3SiCl, MePh2SiCl) runs in more severe conditions and
results in three main products 5–7 (Scheme 3).
The formation of compounds 6 may be explained as follows. The
reaction proceeds along the path (i) very slowly even at severe condi-
tions due to the poor reactivity and steric hindrance in di- and [tri(tert-
butoxy)silyl]methylmagnesium chlorides 3b,c. It is also known that
there may take place the cleavage of THF by halosilanes during pro-
longed reaction mixture boiling [36,37]. This process is accelerated by
iodine, which is used for magnesium activation (Scheme 4).
It should be noted, that the presence of compound 8 being the
product of THF cycle cleavage was indeed confirmed by NMR spec-
troscopy in the case of the reactions of silylmethylmagnesium chlorides
3a,b with Me3SiCl.
All the compounds were identified by NMR spectroscopy in their
reaction mixtures after evaporation of THF. Substances 5a,d and 6c,e,f
were isolated by distillation in vacuum.
(tert-Butoxysilyl)methyl silicon compounds 5a-f with the general
formula Me3-n(t-BuO)nSiCH2SiMeR2, R = Me, Ph, occur as main pro-
ducts of reaction (i) from Grignard reagent 3a containing one only tert-
butoxy group bonded to the silicon (n = 1). The yield of these products
depends on chlorosilane electrophilicity. It amounts to about 63% for
Me3SiCl and increases up to 96% in the case of the more electrophilic
MePh2SiCl.
Compound 8 then interacts with magnesium halides giving mag-
nesium silanolates-halides 9, which react with chloromethylsilanes 2a-
c and produce substances 6a-f (Scheme 5).
At the same time, the presence of two or three tert-butoxy groups in
compounds 3b and 3c (n = 2, 3) unexpectedly leads to preferential
reactions (ii) and (iii) resulting in a mixture of products, out of which
substances Me3-n(t-BuO)nSiCH2OSiMeR2, R = Me, Ph 6b,c,e,f and
Me4-nSi(OBu-t)n 7b,c form predominantly.
It is interesting to note, that chloromethylsilanes 2a-c were detected
in their reaction mixtures by NMR spectroscopy, although the starting
Grignard reagents did not contain these substances at all. Possibly, the
formation of chloromethylsilanes 2a-c may be a result of the halogen
exchange processes in the reaction mixtures.
The results we obtained differ from those reported by D.J. Brondani,
R.J.P Corriu et al. [11,12] on the interaction of [tri(ethoxy)silyl]
(i)
Me3-n(t-BuO)nSiCH2MgCl + MeR2SiCl
Me3-n(t-BuO)nSiCH2SiMeR2 + MgCl2
3a-c
5a-f
(ii)
(iii)
Me4-nSi(OBu-t)n
Me3-n(t-BuO)nSiCH2OSiMeR2 + MgCl2
6a-f
7a-c
R=Me, n=1 (a); n=2 (b); n=3 (c);
R=Ph, n=1 (d); n=2 (e); n=3 (f);
Scheme 3.
6

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
MeR2SiO(CH2)4I + MgX2
MeR2SiOMgX + X(CH2)4I
9
MeR2SiOMgX + Me3-n(t-BuO)nSiCH2Cl
2a-c
Me3-n(t-BuO)nSiCH2OSiMeR2 + MgXCl
6a-f
9
R= Me, Ph; X= Cl, I; n=1-3.
Scheme 5.
Me3-n(t-BuO)nSiCH2Y + MgX2
Me3-n(t-BuO)n-1(XMgO)SiCH2Y + t-BuX
Me3-n(t-BuO)nSiCH2MgCl + t-BuX
Me3-n(t-BuO)nSiCH3 + MgXCl
- C4H8
3a-c
7a-c
X = Cl, I; Y = MgCl, Cl, OSiMeR2, SiMeR2
Scheme 6.
It seems that tert-butoxy substituted methylsilanes 7a-c are formed
owing to CeO bond splitting in the tert-butoxysilyl group by magne-
sium halide, releasing tert-butyl chloride and followed by dehydro-
chlorination of the compound by Grignard reagent 3a-c (Scheme 6). It
should be noted that no isobutene evolution was registered at this stage
of research.
Chemical shifts are shown in Part 2 (Experimental) for those com-
ponents of the mixtures whose signals were assigned. Chemical shifts
for the minor substances are given as a range or omitted.
It should be noted that the highest content (96%) of the type 5
substance is observed in the reaction of 3b with MePh2SiCl. It is of
interest that the structure of 5d exists as two spatial rotational isomers
(5d-I and 5d-II) in a ratio of 13:1 (93% and 7%). From the 2D-corre-
lation spectra we got the full sets 1H, 13C, 29Si signals of both isomers.
The existence of two isomers can be explained by the presence of bulky
substituents (Ph2- and t-BuO-groups) bonded to different silicon atoms
in both 5d-I and 5d-II. The amount of isomer 5d-II increased over time
and the ratio became 3:1 (75% and 25%).
The relative contents of the main compounds present among the
reaction products and chlorosilane conversion degrees are given
(Table 2).
The data presented in Table 2 show that a severe decrease of the
[methyl(tert-buthoxy)silyl]methylsilanes 5a-f content among the reac-
tion products was observed as the number of tert-butoxy groups in the
Grignard molecule increased.
Only 29Si chemical shifts for 5f (its amount 5%) were assigned by
analogy with chemical shifts of 5d and 5e. Assignment of 1H and 13C
chemical shifts was not succeeded.
We believe that the results obtained may be explained by the ob-
structed attack of hindered and highly THF solvated the Grignard re-
agents on the silicon of a chlorosilane. In this case the electrophilicity of
the chlorosilane remains insufficient for the main reaction of chlorine
nucleophilic substitution. It obviously runs very slowly and is outrun by
side reactions.
The formation of O-silylated compounds 6a-f (Scheme 3) was shown
unambiguously by HSQC (1H-29Si, J = 6.5 Hz) correlation spectra. For
example, the proton signal at δ 3.25 (CH2O-group of 6b) has two cross-
3
peaks with silicon atoms at δ −25.3 and 18.3 (2JHCSi and JHCOSi),
which proves the presence of a SiCH2OSi fragment in 6b (Fig. 1).
We fixed the formation of Me3SiO(CH2)4I 8 in the reaction of si-
lylmethylmagnesium chlorides 3a,b with Me3SiCl. We fully assigned
1H, 13C and 29Si signals by COSY, HSQC (1H–13C) and HSQC (1H-29Si)
spectra and proved the structure of 8 in the case of reaction mixture of
3b with Me3SiCl, where content of compound 8 amounted to 10%.
Thus, the proposed mechanism for the formation of an O-silylated
substances 6a-f was confirmed.
3.2.2. NMR spectroscopic analysis of the products obtained from the
reactions of 3a-c with chlorosilanes
The reactions were monitored until the complete disappearance of
proton signals given by the CH2MgCl fragment in the δ range of
−1.5 ÷ −1.3.
Different substance structures were proved in reaction mixtures as a
result of complete analysis of 1D- and 2D-NMR spectra. It was found
that in the studied reactions O-silylated substances 6a-f and 7a-c are
formed besides the expected C-substituted compounds 5a-f (Scheme 3).
The compounds 2a-c and 8 are also found (Schemes 4–6).
The signals assignment of SiMe, SiMe2, SiMe3 and SiCH2-groups for
different compounds was performed on the basis of HSQC (1H-29Si,
J = 6.5 Hz), HSQC (1H–13C, J = 140 and 8 Hz) correlation spectra and
multiplicity of signals in monoresonance 13C NMR spectra. It should be
emphasized that the 2D-correlation spectra allowed us to observe cross-
peaks for those substances, whose content in the mixture was 3–5%.
Thus, the 1H, 13C and 29Si signals of the compounds 5a-f, 6a-f, 7a-c, 8
and 2a-c were completely assigned, their chemical shifts and coupling
The NMR data of compounds 5a-f and 6a-f are presented in Parts
2.5; 2.6 and Tables 3–4.
The chemical shifts (Table 3) for methylene protons of [(tert-bu-
toxysilyl)methyl]trimethylsilanes 5a-c are at δ −0.26 ÷ −0.16 and
shifted downfield up to δ 0.38 ÷ 0.45 for diphenyl substituted com-
pounds 5d,e. Methylene proton signals for O-silylated substances 6a-f
are located at δ 3.11 ÷ 3.50, which is typical for alkoxysilanes [28].
Silicon connected methyl protons for all compounds 5a-e and 6a-f are
observed at δ −0.01 ÷ 0.74 in accordance with known data for methyl
substituted silanes [28,38].
The 13C signals (Table 4) of methylene group for derivatives 5a-e
are located at δ 4.3 ÷ 7.7 with two direct coupling constants
1JCSi = 43.5 ÷ 47.2 and 55.6 ÷ 90.7 Hz [39,40]. Since the value of the
second constant increases significantly, it was assigned to the silicon
with an attached t-BuO-groups.
1
1
constants JHC
,
2JHSi
,
1JCH
,
3JCH
,
1JCSi and JSiC were determined.
Determining the ratio of substances 2, 5–8 in the reaction mixtures
was carried out by the integration of the corresponding signals in the
29Si NMR spectra without taking into account other unidentified neg-
ligible impurities.
Methyl carbon signals for 5a-e appeared at δ 3.5 ÷ 4.9 with
A set of signals for t-BuO- and Ph-groups in the 1H and 13C NMR
spectra was observed in various ratios for different reaction mixtures.
1JCSi
= 57.4 ÷ 71.6 Hz (SiMe3-n), at δ 1.1 ÷ 1.5 with
1JCSi = 50.9 ÷ 51.3 Hz (SiCH3R2, R = Me) and at δ −1.6 ÷ −1.5 with
7

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
Table 2
significant decreasing of its 1JCH to 108 ÷ 109 Hz for compounds 5a-e. This
Chlorosilane conversion degrees and the relative contents of the main com-
pounds in the reactions of Me3-n(t-BuO)nSiCH2MgCl 3a-c with MeR2SiCl,
n = 1–3, R = Me, Ph.
constant is characteristic of the SiCH2Si moiety [42]. The same decreasing
1
of the JCH for the SiCH2O moiety in substances 6a-f has been observed.
1
1
Values of JCH were 129 ÷ 130 Hz instead of JCH = 140 ÷ 143 Hz for
alkoxy group in general organic compounds [42].
n
R
Chlorosilane conversion (%)
Relative content (%)a
As for 29Si signals of tert-butoxy substituted derivatives 5a-f (Part
2.5) and 6a-f (Part 2.6), they are observed in a wide range from δ
−69.7 to 6.9 depending on the number of tert-butoxy groups. It is ty-
pical for alkoxy substituted silanes [28]. As in the case of derivatives
4a-f, the increasing of the number of tert-butoxy groups in the molecule
leads to a significant shielding of the silicon and shifts its signals to the
upfield [28,44].
5a-f
6a-f
7a-c
b,c
b,c
b
d
d
1
2
3
1
2
3
Me
Me
Me
Ph
Ph
Ph
84
86
90
91
56
64
5a
5b
5c
63
32
13
96
15
5
6a
6b
6c
6d
6e
6f
14
40
72
4
7a
7b
7c
7a
7b
7c
10
14
8
e
5d
–
5e
5f
41
51
37
34
d
The 29Si signals of trimethyl substituted silicon for compounds 5a-c
(SiCH2SiMe3) appear in the region of δ −0.6 ÷ −0.3, characteristic of
tetraalkyl substituted silanes [28]. Significant upfield shift of 29Si sig-
nals to δ −8.7 ÷ −7.4 is observed for the methyldiphenyl substituted
derivatives 5d-f compared to trimethylsilyl containing products.
The 29Si signals (SiCH2OSi) for compounds 6a-c are observed in a
narrow δ range of 17.8 ÷ 18.4, characteristic of trimethylalkoxysilanes
[44]. They are shifted upfield to δ −1.8 ÷ −0.8 for methyldiphenyl
substituted products 6d-f.
a
The signals integration data in the 29Si NMR spectra of the reaction mixture
are shown.
b
2a (10%), 2b (4%), 2c (7%) are formed. c 8 (3% for n = 1, 10% for n = 2)
is formed.
d
e
2a is not detected, 2b (7%), 2c (10%) are formed.
5d is a mixture of spatial isomers 5d-I (89%) and 5d-II (7%).
1JCSi = 53.8 ÷ 54.6 Hz (SiCH3R2, R = Ph).
Methylene carbon signals for 6a-f are observed in 13C{1H} NMR
spectra at δ 53.2 ÷ 56.6, which is characteristic of compounds having a
CeO bond [41]. All the signals of methyl carbons bonded to silicon for
6a-f are observed at δ −3.2 ÷ −0.1.
It is of interest that we succeeded to observe a coupling constant
3JSi,Si for the SiCH2OSi-fragment of compound 6c with the greatest
content in the reaction mixture (72%). The value of this constant for
both silicon nuclei is 7.25 Hz.
It can be seen that methyl carbon attached to silicon has a direct
1JCH = 117 ÷ 120 Hz for all compounds 5a-e and 6a-f. The same
constant values were observed for 4a-f (Part 2.4). These constants are
less than normal (1JCH = 125 ÷ 127 Hz) [39,42,43]. Reducing the 1JCH
was not observed when replacing silicon by tin [39].
3.2.3. Gas chromatographic and mass spectrometric (GC/MS) analysis of
the products obtained from the reactions of 3a-c with chlorosilanes
GC/MS has proved to be a useful method for confirming the reaction
paths of the Grignard reagents 3a-c with chlorosilanes. It was studied
by the example of the reaction of the Grignard reagent 3c with Me3SiCl.
The appearance of a second silicon atom at methylene carbon leads to a
Fig. 1. HSQC (1H-29Si, J = 6.5 Hz) correlation spectrum of reaction mixture of 3b with Me3SiCl. 5b - Me(t-BuO)2SiCH2SiMe3, 6b - Me(t-BuO)2SiCH2OSiMe3, 7b -
Me2Si(t-BuO)2, 8 - Me3SiO(CH2)4J, 2b - Me(t-BuO)2SiCH2Cl, * - nonidentified signals.
8

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
Table 3
1H NMR data (C6D6; δ, ppm; J, Hz) for Me3-n(t-BuO)nSi1CH2Si2MeR2 5a-e and Me3-n(t-BuO)nSi1CH2OSi2MeR2 6a-f, n = 1–3, R = Me, Ph.
№
n
R
Me3-nSi1
Si1CH2Si2 (5a-e), Si1CH2OSi2 (6a-f)
Si2MeR2
δ
1JHC
2JHSi
δ
1JHC
2JHSi
δ
1JHC
2JHSi
5aa
1
2
3
1
1
2
1
2
3
1
2
3
Me
Me
Me
Ph
Ph
Ph
Me
Me
Me
Ph
Ph
Ph
0.18
0.20c
–
117.8
117.7
–
6.6
7.0
–
−0.20
−0.16
−0.26
0.39
108.6
108.8
≈109
8.7
0.13
0.17
0.05
0.67
0.59
0.74
0.10
0.09
0.06
0.59
0.59
0.63
118.6
118.5
118.6
6.7
6.6
6.7
6.7
6.5
6.7
6.5
6.6
5ba,b
5ca,d
5d-Ia,e,f
5d-IIa,e,f
5ea,b,f
6aa
8.9
10.3; 8.8
0.07
−0.01
0.06
0.23
0.29
–
118.0
118.0
117.9
118.6
118.8
6.6
6.6
7.1
6.7
7.3
109.4
8.7
119.9
g
g
h
g
0.38
0.45
9.1
4.1
4.7
120.0
118.0
118.2
3.27
129.2
129.1
6ba,b
6ca,d
6df
3.25
–
–
3.11
129.0
5.7
118.2
6.7
g
h
g
h
g
h
0.12
0.34
–
3.31
a,b,f
a,b,f
6e
118.7
–
7.1
–
3.44
130.0
128.7
4.5
5.8
119.4
119.3
6.6
6.6
6f
3.50
a
δ (Me3CO): 1.20 (5a); 1.27 (5b); 1.29 (5c); 1.13 (5d-I); 1.19 (5d-II); 1.21 (5e); 1.22 (6a); 1.31 (6b); 1.29 (6c); 1.29 (6e); 1.39 (6f).
b
c
d
e
f
The reaction mixture after evaporation of the THF.
4JHH = 0.47 t.
Solvent CDCl3.
Spatial rotation isomers.
δ (Ph): 7.18–7.22 (m-Ph and p-Ph); 7.55–7.58 (o-Ph) (5d-I); 7.2–7.6 (5d-II); 7.16–7.22 (m- and p-Ph); 7.59–7.62 (o-Ph) (5e); 7.1 ÷ 7.7 (signals overlap with
product 5d signals) (6d); 7.18–7.23 (m- and p-Ph); 7.65–7.68 (o-Ph); (6e); 7.18–7.24 (m- and p-Ph); 7.69–7.75 (o-Ph); (6f).
g
h
13C satellites were not observed due to overlapping proton signals.
2JHSi failed to observe.
Table 4
Some 13C NMR data (C6D6; δ, ppm; J, Hz) for Me3-n(t-BuO)nSi1CH2Si2MeR2 5a-e and Me3-n(t-BuO)nSi1CH2OSi2MeR2 6a-f, n = 1–3, R = Me, Ph.a
№
n
R
Me3-nSi1
Si1CH2Si2 (5a-e),Si1CH2OSi2 (6a-f)
Si2MeR2
δ
1JCH
1JCSi
δ
1JCH
1JCSi
1JCSi
δ
1JCH
1JCSi
5a
5b
5c
1
2
3
1
1
2
1
2
3
1
2
3
Me
Me
Me
Ph
Ph
Ph
Me
Me
Me
Ph
Ph
Ph
4.3
117.7
117.6
–
57.4
70.6
–
7.1
108.6
108.7
108.7
56.4
68.9
90.7
44.3
43.5
43.6
1.5
118.4
118.4
118.6
119.9
119.8
120.0
118.1
118.1
50.9
51.1
51.3
54.1
53.8
54.6
58.9
58.8
b
c
4.9
7.7
1.4
–
5.8
1.1
d
d
5d-I
4.37
3.5
117.9
118.1
118.0
118.6
118.7
57.8
59.6
71.6
59.8
74.2
4.34
4.31
5.1
109.3
55.6
47.2
−1.5
−1.6
−1.6
−0.7
−0.7
−0.9
−0.3
−3.2
−3.1
e
e
e
e
5d-II
b
5e
4.7
109.2
129.2
129.3
67.6
72.3
89.8
6a
−0.6
−0.3
–
55.8
55.3
53.2
56.6
56.5
55.0
–
–
–
–
–
–
b
c
6b
6c
–
–
128.9
116.4
118.1
58.8
e
e
e
e
e
e
6d
−1.1
−0.1
–
b
b
6e
118.7
–
74.3
–
129.9
89.4
119.5
62.0
62.6
e
e
6f
116.3
a
b
c
d
e
3JCH are shown in Parts 2.5, 2.6.
The reaction mixture, after evaporation of the THF.
Solvent CDCl3.
Spatial rotation isomers.
1
1JCH and JCSi failed to observe.
As mentioned above, the interaction of the Grignard reagents 3a-c
proceeds with the formation of three main compounds: 5a-f, 6a-f and
7a-c. Moreover, the formation of starting chloromethylsilanes 2a-c was
detected by NMR. Indeed, it turned out that the signals of compounds
5c, 6c, 7c and the starting tri(tert-butoxy)chloromethylsilane 2c were
detected in the chromatograms of the reaction products. It is known
that under electron ionization methylsiloxanes easily split off the me-
thyl group [45]. Not molecular ions [M]+, but cations [M−15]+ with
m/z 319, 335, 247 и 281 are observed in mass spectra of compounds
5c, 6c, 7c and 2c, respectively.
level of 10 ÷ 15% for compounds 5c and 6c. These cations have higher
relative intensity (33 and 38%) in the case of tri(tert-butoxy)chlor-
omethylsilane 2c and methyltri(tert-butoxy)silane 7c, respectively. This
fact indicates a greater thermodynamic stability of these particles.
The analysis of mass-spectra for the mixture of the 5c and 6c has al-
lowed an additional proving structure of these substances. Possible paths of
further fragmentation of their cations [M−15]+ has been proposed.
So, for C-substituted compound 5c (M = 334 Da) after forming a
cation with m/z 319 with subsequent splitting off three olefins C4H8,
the formation of silanols takes place [46], resulting in the stable cation
with m/z 151 (Scheme 7). Besides this way of fragmentation in-
tramolecular rearrangements may take place. For example, splitting off
two neutral molecules with 74 and 72 masses gives rise to cations with
m/z 133 and m/z 135 due to the charge transfer on neighboring silicon.
For O-silylated substance 6c characteristic splitting off olefins C4H8
from cation with m/z 335 is observed giving rise to different structure
cations with silanol groups and m/z 167, 223 (Scheme 8).
The total ion current chromatogram for one of the distilled and
enriched in [[tri(tert-butoxy)silyl]methyl]trimethylsilane 5c fraction of
the reaction mixture of the Grignard reagent 3c with Me3SiCl is pre-
sented (Fig. 2).
Data for the fragmentation of these substances under electron io-
nization are presented (Table 5). From the data in the table one can see
that the signal intensity of all cations [M−15]+ is low and is at the
9

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
Fig. 2. The total ion current chromatogram for the reaction mixture of the Grignard reagent 3c with Me3SiCl.
Table 5
Fragmentation data for main reaction products of the Grignard reagent 3c with Me3SiCl.
№
Formula
M, Da
τ ret., min
m/z (I, % rel.)
2c
5c
6c
7c
(t-BuO)3SiCH2Cl
(t-BuO)3SiCH2SiMe3
(t-BuO)3SiCH2OSiMe3
(t-BuO)3SiMe
296
334
350
262
8,32
9,09
8,81b
6,19
283(13)a 281(33) 227(10)a 225(29) 171(35)a 169(100) 135(45) 79(34)
319(15) 263(29) 207(21) 151(100) 135(13) 133(30) 131(19)
335(10) 279(20) 223(35) 167(86) 165(44) 151(28) 135(100) 133(22) 79(30)
247(38) 191(28) 135(100) 117(19) 77(60)
a
b
Cations with 37Cl isotope.
Retention time at the point of chromatographic peak rising at low concentrations coming from chromatographic column. Mass-spectrum distortion is observed in
high concentration on the peak maximum (τ ret. = 8.65 min) due to ion-molecular reactions.
+
+
- Me
- C4 H8
+
(t-BuO)3SiCH2SiMe2
(t-BuO)2(HO)SiCH2SiMe2
(t-BuO)3SiCH2SiMe3
m/z 319
m/z 263
m/z 334
- C4 H8
+
+
- C4 H8
(HO)3SiCH2SiMe2
(t-BuO)(HO)2SiCH2SiMe2
m/z 151
m/z 207
- t-BuOH
(74)
- CH2=SiMe2
(72)
+
+
HOSiCH2SiMe2
(t-BuO)(HO)2Si
O
m/z 135
m/z 133
Scheme 7.
10

E.A. Monin, et al.
InorganicaChimicaActa507(2020)119555
+
- Me
+
- (3 x C4 H8)
+
(t-BuO)3SiCH2OSiMe2
(t-BuO)3SiCH2OSiMe3
(HO)3SiCH2OSiMe2
m/z 167
m/z 335
- (2 x C4 H8)
+
m/z 350
- Me2Si CH2
- CH4
(16)
O
(88)
(t-BuO)(HO)2SiCH2OSiMe2
m/z 223
O
+
(HO)3Si +
m/z 79
(HO)2Si
SiMe
- Me2Si CH2
CH2
m/z 151
O
O
(88)
+
(t-BuO)(HO)2Si
m/z 135
Scheme 8.
Further release of a neutral product with mass 88 from these ca-
tions, apparently extremely unstable oxasilirane [47], gives rise to
hydroxyl containing cations with m/z 79 and 135. In this case, the
cation with m/z 135 is the most stable, probably due to the shielding of
the cationic center by the bulky tert-butoxy group. The formation of the
cation with m/z 151 is apparently due to the splitting off methane from
the cation with m/z 167 with charge transfer to the neighboring silicon.
Thus, the structure of the synthesized disilicon containing com-
pounds was confirmed on the basis of the analysis of the fragmentation
paths of reaction main products by chromatography mass spectrometry.
Acknowledgements
This research did not receive any specific grant from funding
agencies in the public, commercial, or not-for-profit sectors.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://
doi.org/10.1016/j.ica.2020.119555.
References
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Dr. Alexander M. Philippov graduated with honors from
the Patrice Lumumba Moscow people's Friendship
University in 1974, where he improved his skill in mass-
spectrometry study of catalytic reactions until 1977. He
works in the SSC RF GNIIChTEOS from 1978. His thesis
(1990) deals with the reactivity of various bonds in orga-
noelement compounds under the fluorinated agents impact.
Now he is working on structure elucidation of organoele-
ment compounds formed in catalytic processes, as well as
products purity by chromatography-mass spectrometry.
Academician of the RAS (2019), dr. Pavel A.
Storozhenko graduated from Chemistry Department of the
Lomonosov Moscow State University in 1973. He works in
SSC RF GNIIChTEOS from 1981 up to date. He is the gen-
eral director of the institute from 2001. His scientific in-
terests are developing a new high temperature composites
for aerospace and high pure materials for electronics,
chemistry and technology of hydrides and organoelement
compounds.
13