Synthesis and reactivity of novel bis(stannyl)silanes

Article abstract of DOI:10.1515/znb-1999-0916

Bis(stannyl)silanes of types R₃Sn-SiR′₂-SnR₃ and R₂(H)Sn-SiR′₂-Sn(H)R₂ with R′ being methyl, phenyl, iso-propyl or tert-butyl have been synthesized by treatment of difunctionalized diorgano

Full text of DOI:10.1515/znb-1999-0916

Synthesis and Reactivity of Novel Bis(stannyl)silanes
P. Bleckmannb, U. Englich0, U. Hermann11,1. Prassa, K. Ruhlandt-Sengec,
M. Schürmann3, C. Schwittekh, and F. Uhlig3*
a Fachbereich Chemie der Universität Dortmund, Anorganische Chemie II,
Otto-Hahn-Straße 6, D-44221 Dortmund, Germany
b Fachbereich Chemie der Universität Dortmund, Organische Strukturchemie,
Otto-Hahn-Straße 6, D-44221 Dortmund, Germany
c Syracuse University, Department of Chemistry,
1-014 Center of Science and Technology, Syracuse, N.Y., USA
* Reprint requests to Dr. F. Uhlig. Fax: (+49) 231 755 3797.
E-mail: fuhl@platon.chemie.uni-dortmund.de
Dedicated to Prof. Dr. H. Oehme on the occasion ofhis 60th birthday
Z. Naturforsch. 54 b, 1188-1196 (1999); received June 30, 1999
Stannylsilanes, Rearrangement, Reactions with Alkynes, X-Ray Data
Bis(stannyl)silanes of types RjSn-SiRVSnR} and R2(H)Sn-SiRS-Sn(H)R2 with R' being
methyl, phenyl, z'so-propyl or terf-butyl have been synthesized by treatment of difunctionalized
diorganosilanes with alkali stannides (R = Me, 'Bu; R’ = Me, 'Pr; 1 -6, 8) or with triphenyl-
tin chloride and magnesium (R = Ph; R’ = Me, Ph, 'Pr; 7, 9). Me.^Sn-Si'Bua-SnMe.^ 4, was
halogenated using SnCU, to yield the bis(chlorostannyl)silane 11.
The reaction of bis(stannyl)diorganosilanes R^SnSiRSSnRj with catalytic amounts of
Pd(PPh3)4 resulted in unexpected rearrangements under formation of the silyldistannanes
R3SnSnR2SiR’R2. These compounds undergo addition reactions with alkynes. All compounds
have been identified by NMR, IR, MS and elemental analysis. Compounds 5, 6 and 7 have also
been characterized by X-ray crystallography.
Compounds of type A are expected to be particu-
1. Introduction
lary suitable as precursors for cyclic stannylsilanes
with di- or tristannyl moieties and ring sizes of four,
five and six atoms [7]. Toinvestigatethereactivity of
differently substituted bis(stannyl)diorganosilanes,
compounds of the types B and C have been syn-
thesized. The distinction between type B and C
derivatives is based on the steric demand of lig-
ands connected to the tin atoms: compounds of type
B carry small substituents, while type C derivatives
feature rm.butyl ligation in addition to a hydride
function.
Stannylsilanes are well known and frequently
used reagents in organic synthesis [1]. The focus
of our interest is the investigation of tin-silicon sys-
tems asprecursorsforpolymeric species. The devel-
opment of these systems mandates a detailed inves-
tigation of the reactivity of the precursor molecules.
This includes the exploration of reactions of stan-
nylsilanes treated with alkynes in the presence of
Pd catalysts [2 -5].
Recently, we described the synthesis of a,u;-bis-
(chloro- and bromostannyl)oligodimethylsilanes of
type A [6]. The preparation of these compounds is
only possible if the steric demand of the substituents
Our investigations have also focused on the re-
activity of bis(stannyl)silanes towards alkynes in
the presence of transition metal compounds. Sur-
prisingly, we encountered rearrangements of type B
stannylsilanes in the presence of palladium com-
plexes, followed by alkyne insertion reactions.
Bis(stannyl)silanes of type C do not undergo these
rearrangementsdue tothe sterically demanding sub-
stituents at the tin atoms.
at the tin atoms is large (e. g. terr-butyl); utilization
of smaller groups results in cleavage ofSi-Sn bonds.
R2Sn(X)-(SiMe2)„-Sn(X)R2 (A)
R = 'Bu; X = Cl, Br; n = 2-6
R2Sn(Z)-SiR'2-Sn(Z)R2(B, C)
B: R = Z = Me, Ph; R' = 'Bu, 'Pr, Me
C: R = 'Bu, Z = H. R1= Me, 'Pr
K
0932-0776/99/0900-1188 $ 06.00 (c) 1999 Verlag der Zeitschrift für Naturforschung. Tübingen • www.znaturforsch.com
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1189
P. Bleckmann et al. ■Synthesis and Reactivity of Novel Bis(stannyl)silanes
Table I. Yields and starting materials (X-SiRVX; MSn-
RtZ) for the syntheses of the bis(triorganostannyl)silanes
1-9.
owing to the steric shielding at both the silicon
and the tin atom by the rm-butyl groups. Only un-
changed starting materials were isolated:
R
Z
R'
X
M
Yield
No.
'Bu2SiCl2 +2 LiSn'(H)Bu2
H'Bu2Sn-'Bu2Si-Sn'Bu2H (10)
(3)
Me
H
Me
Me
Me
H
Ph
Ph
Ph
Ph
Me
'Bu
Me
Me
Me
'Bu
Ph
Ph
Ph
Ph
Me
Me
Pr
'Bu
'Bu
'Pr
Cl
Cl
F
OTf
Cl
Cl
Cl
Cl
OTf
F
Na
Li
Na
Li
K
Li
80%
89%
74%
88%
65%
97%
60%
95%
80%
75%
1 [6]
2 [6]
3
2.2. Reactivity
4
In contrast to derivatives of the type Me^Sn-
(SiMe2)„-SnMe3 (n > 1) and the stannylsilanes 3,
7 and 9, compound 4 can be halogenated at the tin
centers without cleavage of the Si-Sn bond. A clas-
sic redistribution reaction involving treatment with
SnCU yields the dihalogenated compound (eq. (4)).
The steric shielding effectedby therm-butyl groups
in 4, as compared to methyl, /so-propyl or phenyl
substituents in 3, 7 and 9, is responsible for the
selectivity of this reaction route.
5
Li
6 [6]
Me
'Pr
'Bu
Ph/Me
7
8
9
Mg
Na
Mg
2. Results and Discussion
2.1. Syntheses
All compounds were synthesized according to
reaction routes developed for the synthesis of
bis(stannyl)dimethylsilanes [6]. However, metathe-
sis reactions with difluorosilanes are slow, espe-
cially in conjunction with sterically demanding sub-
stituents such as tert-butyl or /so-propyl. Introduc-
tion of chloro- or triflate-substituted silanes, rather
than the fluoro derivatives, facilitates the reaction.
Bis(stannyl)silanes R^Sn-SiRVSnR^ were ob-
tained in high yields by treatment of difunction-
alized diorganosilanes with alkali tri- or diorganyl-
stannides (1 -6 , 8 , eq. (1)) or, alternatively, by re-
action with triphenylchlorostannane in the presence
of magnesium (7, 9, eq. (2)).
Me3Sn-‘Bu2Si-SnMe3 (4)
(4)
—2 /3 Me^Snci>Me2Sn(Cl)-'Bu2Si-Sn(Cl)Me2 (11)
Reactions leading toderivatives with fouror more
chlorine atoms at the Si-Sn skeleton are still under
investigation and will be discussed in a subsequent
publication.
As recently observed [6], halogenation of a,uo-
bis(di-rm-butylhydridostannyl)dimethylsilanes
with more than one silicon atom separating the tin
centers, to yield type A compounds, can be eas-
ily achieved by employing haloforms. Unlike these
derivatives, the comparable monosilyl hydrides 2
and 5 [6 ]cannot be transformed into the halides.
R'2SiX2 +2 MSnR2Z
R2Sn(Z)-R'2Si-Sn(Z)R2(l)
X = F, Cl, CF3SO3; M = Li, Na, K
H-'Bu2Sn-R2Si-Sn-'Bu2H
(5)
1: R = Z = R' = Me
+2chx3
2: R = 'Bu,Z = H, R '= Me
3: R = Z = Me, R’ = 'Pr
4: R = Z = Me, R’ = 'Bu
5: R = 'Bu, Z = H, R’ = 'Pr
6: R = Z = Ph, R' = Me
8: R = Z = Ph, R’ = 'Bu
-f-f—r X-'Bu2Sn-R2Si-Sn-'Bu2X (2: R = Me; 5: R = 'Pr)
Instead, treatment of 2 and 5 with CHX3 (X =
Cl, Br), SnCU or PCI5 results in Si-Sn bond cleav-
age under formation of oligomeric stannanes and
halosilanes. With milder halogenation agents such
as MenSiCU_„ / amine no reactions are observed.
R’2SiX2 +2 Ph3SnCl _2+^ | )C| Ph3Sn-R’2Si-SnPh3 (2)
X = F, Cl
In order to examine the reactivity of 1 - 9 to-
wards transition metal complexes, we treated 1, 3
and 7 with tetrakis(triphenylphosphine) palladium
(eq. (6 )). Surprisingly, a novel and unexpected re-
arrangement of the Sn-Si-Sn fragment under forma-
tion of distannylsilanes 12-14 with a Sn-Sn-Si atom
7: R' = 'Pr; 9: R' = Ph/Me
In contrast to the reactions illustrated in eq. (1),
treatment of di-terf-butyldichlorosilane with two
equivalents of lithium di-rm-butylhydridostannide
did not result in the desired product 10 probably sequence was observed.
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1190
P. Bleckmann et al. • Synthesis and Reactivity of Novel Bis(stannyl)silanes
Me3Sn-SiMe2-SnMe;
+ Pd(PPh3)4
+ R'C=CR”
^
.
Me2
S i
Me,Sn
SnMe.
Me3Sn-SnMe2-SiMe3
K M
12
R
R” R”
Me,Sn-SnMe2,
SiMe,
Scheme l. Rearrangement of 1and reaction
with alkynes in the presence of Pd(PPh3)4.
15, R = Ph
16, R= CH,-OCH3
H
Table II.1l9Sn and 29Si NMR data of compounds 1-9 and
11; chemical shifts [ppm] and coupling constants [Hz],
R3Sn-SiR'2-SnR3 +Pd(PPh?>4>R3Sn-SnR2-SiR’2R
(6)
12: R = Me, R'= Me
13: R = Me, R'= 'Pr
14: R = Ph, R = 'Pr
R
R'
No.
Z
<$l,9Sn
<529Si
^•/Sn-Sn
'^Si-Sn
la Me Me Me
-98.4
-111.3b
-108.3
-110.2
-104.4°
-155.5
-157.0
-160.0
-1627.0
119.5
703
-
-38.3 508/486
-34.9 347/331
-1.4 447/426
10.9 445/425
This rearrangement is only observed if small
substituents are present at the silicon center. Bis-
(stannyl)silanes carrying the sterically more de-
manding rm-butyl groups (e. g. compound 4) do
not undergo the rearrangement. The application of
heat (up to 100 °C) did not give better results; only
Si-Sn bond cleavage was observed. Reacting the hy-
drido substituted derivatives 2 and 5 with Pd(PPh3)4
also resulted in tin-silicon bond cleavage.
2a 'Bu
H
Me Me
Me
'Pr
3
4
655
609
190
712
661
615
570
900
Me Me 'Bu
'Bu 'Pr
Ph Ph Me
Ph
Ph Ph
Ph Ph Me/Ph
'Bu
H
5
6a
7
8
11.7
256/245
-31.9 521/497
437/417
Ph 'Pr
'Bu
7.8
12.8 437/417
9
-31.4
32.4
n.d.
443/422
11 Me
Cl
aSee lit. [6];b '7Sn-H = 1280 Hz;c]JSn-H= 1257 Hz.
The rearrangement product 12 (eq. (6)) reacts in
the presence of catalytic amounts of Pd(PPh3) with
one equivalent of an alkyne in a regioselective cis-
addition to the /3-distannylvinylsilanes 15 and 16
(Scheme 1). We were unable to find any indication
for an insertion reaction of a second equivalent of
alkyne into the Sn-Sn bonds of 15 or 16. Alteration
of the reaction conditions and stoichiometric ratio
of the starting materials did not change this result.
Products 15 and 16 are also available by treat-
ing 1 with alkynes in the presence of tetrakis(tri-
phenylphosphine) palladium in a one-pot reaction.
arising from the formation of the Sn-Sn-bond. This
thermodynamic statement is also verified by exper-
iments conducted according to eq. (6 ).
2.3. Characterization
1l9Sn and 29Si NMR data of 1-9,11 and 12 - 16
are summarized in Tables II and III. Remarkably,
the distannyl derivatives 12 -16 do not show simple
AX-spin systems for the '^ i^ s n —,,9Sn coupling satel-
lites (Table III); the distannyl derivatives 12 -14 ex-
It is believed that 12 is the intermediate in this rear- hibit AM type spin systems, and forthe /3-distannyl-
rangement reaction.
vinylsilanes 15 and 16 AB type satellites have been
found.
In order to compare the thermodynamic stabili-
ties of compounds 1and 12,we performed semiem-
pirical geometry optimizations using PM3[10]
methods. For 1 we calculated -164.098 kJ/mol as
heatofformation; for 12, avalue of-226.945 kJ/mol
X-ray-quality crystals of compound 5 were ob-
tained by crystallization from a saturated «-hex-
ane solution, compounds 6 and 7 were crystal-
lized from diethylether. Compounds 5 - 7 ex-
was obtained. Density functional calculations using hibit almost perfect tetrahedral geometry about the
the ADF program1" 1 afforded -16177.585 kJ/mol silicon and tin centers. Small deviations from tetra-
for 1and-16247.128 kcal/mol for 12 as total bond- hedral geometry are induced by sterical effects.
ing energies after a geometry optimization [12], Si-Sn, Si-C and Sn-C distances are within the usual
range.
confirming that 12 is more stable than 1, a fact
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P. Bleckmann et al. • Synthesis and Reactivity of Novel Bis(stannyl)silanes_____________________________________1191
Table III.
No.
1l9Sn and 29Si NMR data of compounds 11 -
15; chemical shifts [ppm] and coupling constants [Hz].
R
R'
<5119Sn a
<$ll9Sn b
629Si
•^Sn —Sn
'•/Si-Sn
~*Asi —Sn
Jsi —Sn
12
Me
Me
Ph
Me
Me
Me
<Pr
-111.7
-110.8
-147.7
-98.4
-263.6
-274.6
-241.2
-140.5
-150.4
2825/2700
2935/2805
2645/2527
4235/4050
4770/4560
-8.1
14.4
16.3
11.7
32.4
527/503
485/463
484/463
—
84
69
70/67
13a
14
15
16
'Pr
Me
Me
32
34
_
-97.3
aOnly determined by 29Si- and ll9Sn NMR spectroscopy.
Table IV. Selected interatomic bond distances (A) and
angles (deg) for 5, 6 and 7.
5
6
7
Si(1)-Sn(1)
Si(l)-Sn(2)
Si(l)-C(19)
Si(l)-C(20)
Sn(l)-H(l)
2.5713(4)
2.6061(16)
2.6094(15)
1.915(5)
1.907(6)
1.79(4)
2.5935(9)
2.5946(9)
1.898(4)
1.899(4)
1.875(2)
1.875(3)
Sn(2)-H(2)
Sn(l)-Si(l)-Sn(2)
C( 19)-Si(1)-Sn( 1) 106.17(15)
1.78(4)
111.29(5)
116.49(3) 109.11(3)
107.28(9) 106.96(13)
106.34(15) 108.33(9) 107.19(13)
C(20)-Si(l)-Sn(l)
C(19)-Si(l)-Sn(2) 112.96(17)
C(20)-Si(l)-Sn(2) 113.42(17)
C(19)-Si(l)-C(20) 106.7(2)
111.59(12)
112.35(13)
109.4(2)
Fig. 1. X-ray structure of 5. Thermal ellipsoids denote
50% of probability displacement (ORTEP3).
109.0(2)
105.41(7)
C(l)-Sn(l)-C(7)
C(l)-Sn(l)-C(13)
C(13)-Sn(l)-C(7)
108.4(2)
102.92(13)
reference Me4Si or Me4Sn) or a Bruker DRX 300 spec-
trometer (solvents hexane or thf with D20 capillary).
Mass spectral analyses were recorded using a MAT 8200.
Elemental analyses were performed on a LECO-CHNS-
932 analyzer.
106.50(7) 104.48(13)
110.04(7)
107.71(13)
103.6(2)
106.0(2)
C(25)-Sn(l)-C(31) 110.69(15)
C(25)-Sn(l)-C(37)
C(31)-Sn(l)-C(37)
106.48(14)
C(l)-Sn(l)-H(l)
C(7)-Sn(l)-H(l)
Si( 1)-Sn(1)-H(1)
C-Sn-Si
89.8(18)
101.1(18)
108.8(18)
112.55(17)
3.1. Syntheses ofbis(stannyl)silanes
General procedurefor compounds 3, 4, 6 and
8
106.51(5) 110.76(9)
116.44(17) 112.93(5) 113.84(9)
116.86(17) 115.19(5) 113.07(11)
In a 100 ml Schlenk tube the adequate amount of
hexaorganodistannane was dissolved in thf. Sodium and
naphthalene were added. The resulting reaction mixture
was stirred at r. t. for 14 h. After filtration to remove ex-
cess sodium, the resulting solution of sodium triorgano-
stannide was added slowly to acooled solution (-40 °C) of
difunctionalized diorganosilane dissolved in thf. The mix-
ture was stirred for 3 h at -40 °C and then slowly warmed
to r. t.. After evaporation of the volatiles in vacuum the
residue was extracted twice with 80 ml of an ether/hexane
mixture (80:20). Theextracts were filtered (G3) to remove
the sodium salts. The solvents were removed in vacuum
and the crude product purified by distillation or crystal-
lization.
116.90(11)
117.20(17)
117.53(10)
111.11(10)
113.87(9)
118.00(9)
3. Experimental
General
All reactions were carried out under an atmosphere
of inert gas (N2 or argon) using modified Schlenk tech-
niques. All solvents used were dried by standard methods
and freshly distilled prior to use. The bis(stannyl)dime-
thylsilanes 1, 2 and 6 and the alkali stannides were pre-
pared according to published procedures [6, 8, 9]. All
other reagents were obtained commercially. 1H, l3C, 29Si
and ll9Sn NMR spectra were recorded using a Bruker
Bis(trimethylstannyl)diisopropylsilane
3
Me6Sn2 (6.6 g, 20 mmol) in 80 ml of thf, sodium
(1 g, 40 mmol), naphthalene (0.1 g, 4 mmol) and diflu-
DPX 400 spectrometer (solvents CDCI or CöDö, internal
3
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P. Bleckmann et al. ■Synthesis and Reactivity of Novel Bis(stannyl)silanes
Fig. 3. X-ray structure of 7. Thermal ellip-
soids denote 50% of probability displace-
ment (ORTEP3).
orodi/sopropylsilane (3.0 g, 20 mmol) in 20 ml of thf. -
Yield: 6.5 g (74%) of 3 as a colorless liquid, b. p. 66 -
Procedure b: Hexamethyldistannane (2.5 g, 7.6 mmol),
sodium (0.35 g, 15.2 mmol), naphthalene (0.1 g, 4 mmol)
and di-terf-butyldichlorosilane (1.6 g, 7.6 mmol) in 10 ml
thf). Yield: 2.3 g (65%) of 4 as a colorless solid, m. p.:
70 °C (0.005 mm Hg). - 1H NMR (400.13 MHz, C6D6)
6
0.14 (s, 18 H, Sn(C//3b, 2ySn-H =46 Hz), 1.06 (d, 12 H,
78 -80 °C. - 1H NMR (400.13 MHz, C6D6)
6 0.18 (s, 18
C//3, ' / h —h = 7 Hz), 1.43 (m, 2 H, CH, ' / h- h = 7 Hz). -
13C {'H} NMR (100.63 MHz, C6D6)
6 -9.1 (Sn(CH3)3,
H, Sn(CH3)3, 2/s n -H = 48 Hz), 1.61 (s, 18 H, C(CH3)3).
- MS m/z (%): 470 [M+/ 10%], 455 [M+-Me / 5], 317
[M+-SnMe3/ 20], 163 [Me3Sn+/ 25], 142 [Si'Bu2/100],
Vsn-c = 245/234 Hz), 14.4 (SiCH, 2/Sn-c = 40 Hz), 21.6
(SiCH(CH3)2, ]Jsn-c = 245 Hz). MS m/z (%): 442 [M+/
3%], 427 [M+-Me / 6], 279 [M+-SnMe3 / 34], 237 [M+-
SnMe3-'Pr / 9], 163 [Me3Sn+/ 19], 129 [Si'Pr2Me / 95],
Elemental analysis for Ci4H36SiSn2(469.95 g/mol)
Calcd C 35.8 H 7.7%,
Found C 36.2 H 7.4%.
Elemental analysis for C]2H32SiSn2(441.89 g/mol)
Calcd C 32.6 H 7.3%,
Found C 33.7 H 7.7%.
Bis(triphenylstannyl)di-tert-butylsilane
8
Bis(trimethylstannyl)di-tert-butylsilane
4
Hexaphenyldistannane (7.15g, 10.2 mmol), sodium
(0.47 g, 20.4 mmol), naphthalene (0.1 g, 4 mmol) and
di-rm-butylsilylbis(trifluoromethanesulfonate) (4.49 g,
3.3 ml. 10.2 mmol) in 20 ml thf. Yield: 3.8 g (88%)
of 8 as a colorless solid. - 1H NMR (400.13 MHz, CöDö)
Procedure a: Hexamethyldistannane (3 g, 9.2 mmol),
sodium (0.43 g, 18.7 mmol), naphthalene (0.1 g,
4 mmol) and di-ter/-butylsilylbis(trifluoromethanesul-
fonate) (3.0 g, 9.2 mmol) in 20 ml thf. Yield: 3.8 g (88%)
of 4 as a colorless solid.
6
7.10- 7.8 (m, 30 H, Ph), 1.71 (s, 18 H, C(CH3)3). - MS
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P. Bleckmann et al. ■Synthesis and Reactivity of Novel Bis(stannyl)silanes
1193
m/z (%): 842 [M+/ 5%], 785 [M+-'Bu / 5], 765 [M+-Ph /
3], 434 [Si'BuSnPh3/ 25], 349 [Ph3Sn /100], 142 [Si'Bu2
/ 10], 85 [Si'Bu / 40].
(400.13 MHz, CDC13)
b
1.18 (d, 12 H, CH(C//3)2), 1.43
(m, 2 H, C//(CH3)2), 7.20 (m, 18 H, m-Ph, p-Ph), 7.62
(d, 12 H, o-Ph, Vsn-H = 43 Hz). - ,3C {‘H} NMR
(100.63 MHz, C6D6)
b 15.4 (SiCH, 2/Sn-c = 24 Hz), 22.0
Elemental analysis for CwHjgSiS^ (832.29 g/mol)
Calcd C 62.7 H 5.7%,
Found C61.9 H 5.6%.
(SiCH(CH3)2, Vsn-c = 20 Hz), 128.3 (p-Ph), 128.4 (m-
Ph,Vsn-c = 44 Hz), 137.6 (o-Ph,27Sn-c = 37 Hz) 140.0
(/-Ph, '7sn-c = 389/371 Hz). - MS m/z (%): 736 [M+-Ph
/ 2], 465 [M+-SnPh3 / 21], 388 [M+-SnPh3-Ph / 47], 345
[M+-SnPh3-Ph -'Pr/ 11], 197 [PhSn+/ 39], 149 [Si'PrPh+
/ 100], 121 [SiPhMe+/ 73].
Bis(di-tert-butylstcinnyl)diisopropylsilane
5
A solution of n-butyllithium (6.3 ml, 10 mmol, 1.6 M
in hexane) was added dropwise to a cooled (-70 °C) so-
lution of di-/so-propylamine (1.0 g, 10 mmol) in a mix-
ture of 15 ml hexane and 15 ml thf. The mixture was
stirred for 20 min at 0 °C. The resulting lithium di-
isopropylamide (LDA) solution was added dropwise to
a cooled (-65 °C) solution of di-ter/-butyltindihydride
(2.4 g, 10 mmol) in 50 ml of hexane and 50 ml of thf.
The reaction mixture was slowly warmed to -50 °C and
di-wo-propyldichlorosilane (0.93 g, 5 mmol) was added.
After warming the reaction mixture to -30 °C, 25 ml of
petrol ether (30 -60 °C) was added and stirred for one
hour at -10 °C. The mixture was hydrolyzed by addi-
tion of 20 ml of water. The organic layer was separated
and dried using calcium chloride. After removal of the
drying agent the solvents were evaporated, yielding 2.8 g
(97%) of5as acolorless crystalline product, m. p. 76 °C. -
Elemental analysis for CoRwSiSn? (814.32)
Calcd C 62.0 H 5.5%,
Found C 61.8 H 5.5%.
Bis(triphenylstannyl)phenylmethylsilane 9
Compound 9was prepared according to the procedure
of derivative 7. Starting materials: triphenylchlorostan-
nane (7.15 g, 18.6 mmol), Mg turnings (2.0 g, 83 mmol)
and phenyl(methyl)difiuorosilane (1.47 g, 9.3 mmol) in
40 ml of thf. - Yield: 6.7 g (88%) of 7 as a colorless solid,
m.p. 166 - 167 °C. - 'H NMR (400.13 MHz, C6D6)
b
7.12 -7.75 (m, 35 H, Ph), 0.71 (s, 3 H, SiCH3, 3JSn-H=
46 Hz).- MS m/z (%): 820 [M+/ 2%], 743 [M+-Ph / 5],
471 [M+-SnPh3/ 60], 349 [Ph3Sn / 100],
Elemental analysis for G^H^SiSni (820.28 g/mol)
Calcd C 63.0 H 4.7%,
Found C 62.2 H 4.9%.
1H NMR (400.13 MHz, C6D6)
Vh-h = 7 Hz), 1.50 (s, 36 H, C(C//3)3, ^('H-'^Sn) =
63 Hz), 1.72 (septett, 2 H, C//(CH3)2, V h- h
7 Hz),
5.3 (s, 2H, SnH, ]JS = 1257 Hz, 'ySn-H = 1201 Hz).
- I3C {'H} NMR (100.63 MHz, C6D6) 16.3 (SiCH,
b 1.28 (d, 12H, CH(C//3)2,
=
n
-
H
3.2. Reactions with tin(IV)chloride
b
Bis(chlorodimethylstannyl)di-tert-butylsilane 11
Vsn-c = 19Hz), 23.2 (SiCH(CH3)2, V Sn-c = 16Hz), 30.3
(SnC(CH3)3, '/sn-c = 308 Hz, 17(l3C-1,7Sn) = 294 Hz),
A solution of 1.4 g (3 mmol) 4 and 0.52 g (0.23 ml,
34.7 (SnC(CH3)3). - MS m/z (%): 582 [M+/ 3], 525 [M+- 2 mmol) SnCL in a mixture of 5 ml of thf and 5 ml of
rBu / 21], 467 [M+-2'Bu /11 ], 353 [H2'Bu2Sn2+/ 74], 297
[H3'BuSn2+/ 80], 177 [H2'BuSn+/ 29], 57 ['Bu+/ 100],
43 ['Pr+/ 55]. - IR (nujol) i/(Sn-H)= 1771 cm"1.
toluene were stirred overnight at r. t.. The solvent was re-
moved in vacuo. Crystallisation from diethylether yielded
1.3 g (2.5 mmol / 85%) of 11 as a colorless solid. - MS
m/z (%): 510 [M+/ 2%], 492 [M+-Me / 5]; 475 [M+-C1 /
2], 440 [M+-2C1/10], 347 [M+-SnMe3/ 60]; 148 [Me2Sn
/ 100],
Elemental analysis for C22Hs2SiSnT (582.16 g/mol)
Calcd C 45.4 H 9.0%,
Found C 43.8 H 9.0%.
Elemental analysis for C]2H3oCl2SiSn2 (510.78)
Calcd C 28.2 H 5.9%,
Found C 28.8 H6.1%.
Bis(triphenylstannyl)diisopropylsilane
7
In a 100 ml Schlenk tube dichlorodi/sopropylsilane
(0.5 g, 2.5 mmol) and triphenyltin chloride (1.9g, 5mmol)
were dissolved in 80 ml ofthf. Magnesium turnings (0.9 g,
37 mmol) were added. The reaction mixture was stirred
at r. t. for approx. 120 h. After evaporation of the thf,
the oily residue was extracted twice with 80 ml of a
ether/hexane mixture (80:20). The extracts were filtered
(G3) to remove magnesium salts. The crude product was
obtained after evaporation of the solvents in vacuum. Pu-
rification was by recrystalisation from etheryielding 2.0 g
(95%) of 7 as a colorless solid, m.p. 145 °C. - 'H NMR
3.3 General procedure for a rearrangement of bis(tri-
organostannyl)silanes with Pd(PPhj)4
A
solution of 2.5 mmol of a stannylsilane and
0.05 mmol of tetrakis(triphenylphosphine) palladium in
20 -25 ml of toluene was stirred for 15 h at 60 °C. The
solvent was removed under reduced pressure and 25 ml
of diethylether was added. The solution was filtered (G3)
and the solvent was removed in vacuo. The remaining
residue was purified by destination or crystallisation.
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1194
P. Bleckmann et al. ■Synthesis and Reactivity of Novel Bis(stannyl)silanes
Octamethyl-1-sila-2,3-distannapropane 12
gel, followed by removal of the solvent in vacuo. Yields:
15: 1.17 g (57%), 16: 0.33 g (30%).
0.8 g (2.1 mmol) of 1 and 0.2 g (0.17 mmol) of
Pd(PPh3)4 were dissolved in 5 ml of toluene. Adsorptive
filtration of the crude product using n-hexane as mobile
phase yielded 0.65 g (1.7 mmol / 81%) of 11 as a colorless
highly viscous oil. - CsH24SiSn2, 345.7 g/mol. - 1H NMR
(400.13 MHz, CDC13) 6:0.171 (s, 6 H, Sn(C//3)2,2JSn-H=
25 Hz), 0.170 (s, 9H, Sn(C//3)3, 2JSn-H= 26 Hz), 0.23 (s,
9 H, Si(C//3)3, 3JSn-H= 24 Hz); ,3C {‘H} NMR (100.63
MHz, CDC13) «5:-5.4 (s, '/Sn-c = 184/176 Hz, Sn(CH3)2),
-9.4 (s, ‘7Sn-c = 230/220 Hz. Sn(CH3)3), 1.5 (s, '/sn-c =
55/44 Hz, Si(CH3)3). - MS m/z (%):384 [M+, 5%], 369
[M+-Me], 311 [M+-SiMe3/ 7], 223 [M+-SnMe3/ 20], 73
[SiMe3 / 100],
Spectroscopic data
15: 'H NMR (400.13 MHz, CDC13) 6: 0.18 (s, 9 H,
Si(CH3)3), 0.185 (s, 9H, 27 Sn- H = 49/47 Hz Sn(CH3)3),
0.27 (s, 6 H, l/ s n - H = 47/45 Hz, Sn(CH3)2), 6.55 (s, 1H,
Vsn-H = 175/167 Hz, Me2SnC=C//), 6.98 (m, 2 H, Ph),
7.14 (m, 1 H, Ph), 7.26 (m, 2 H, Ph)\ l3C {'H} NMR
(100.63 MHz, CDC13) 6: -9.4 (s, 'j Sn-c = 250/238 Hz,
Sn(CH3)3), -6.5 (s, '7Sn-c = 238/227 Hz, (CH3)2), 0.4 (s,
S(CH3)3), 125.7 (s, Ph), 125.9(s,Ph), 128.0(s,Ph), 147.5
(s, 2ySn-c = 62 Hz, C=CSiMe3), 151.7 (s, 27Sn-c = 52 Hz,
i-C, Ph), 165.6 (s, '7sn-c = 340/326 Hz, Me2SnC=C).
- MS m/z (%): 486 [M+ / 5%], 471 [M+-Me / 59],
325 [M+-SnMe3 / 79], 175 [M+-SnMe2SnMe3 / 44], 73
[SiMe3/ 100]
/, I-Diisopropylhexamethyl-1-sila-2,3-distanna-
propane 13
16: 'H NMR (400.13 MHz, CDC13) 6: 0.10 (s, 9 H,
Si(CH3)3), 0.21 (s, 9 H, 27Sn-H = 49/47 Hz Sn(CH3)3),
0.31 (s, 6 H, 2ySn—h = 47/45 Hz, Sn(CH3)2), 3.27 (s, 3
H. CH20 Me), 4.00 (s, 2H, 37 Sn- H = 18 Hz, CH2OMe),
6.56 (s, 1H, Vsn-H = 178/170 Hz, Me2SnC=C//). - l3C
{'H} NMR (100.63 MHz, CDC13) 6: -9.4 (s, 'ySn-c =
248/236 Hz, Sn(CH3)3), -8.0 (s, ‘/sn-c = 239/228 Hz,
Sn(CH3)2), 0.2 (s, Si(CH3)3), 57.5 (s, CH20 Me), 84.8 (s,
2ySn-c = 57 Hz, CH2OMe), 143.5 (s, 2JSn-c = 55 Hz,
C=CSiMe3), 162.2 (s, 7 Sn-c = 340/325 Hz Me2SnC=C).
- GC-MS m/z (%): 441 [M+-Me / 100], 293 [M+-
SnMe3/ 97],
1.25
g (2.8 mmol) of 3 and 0.2 g (0.17 mmol) of
Pd(PPh3)4 were dissolved in 5 ml of toluene. Adsorptive
filtration of the crude product using n-hexane as mobile
phase yielded 1.1 g (1.68 mmol) of a colorless highly
viscous oil. The composition of the reaction mixture was
determined by 29Si and n9Sn NMR spectroscopy. The
product mixture contains 80 -85% of 13 and between 15
and 20% of starting material 3 which we were unable to
separate.
1,1 -diisopropylhexaphenyl-1-sila-2,3-distanna-
propane 14
Crystallographic analysis: Crystals of 5 and 6 were
removed from the Schlenk flask under a stream of N2and
immediately covered with a layer of viscous hydrocarbon
oil (Paratone N, Exxon). A suitable crystal was selected
under the microscope, attached to a glass fiber, and imme-
diately placed in the low-temperature nitrogen stream of
thediffractometer [16]. The data setsfor compounds 5and
6 were collected using a Siemens SMART system at 86 K
(custom built low-temperature device, Prof. H. Hope),
complete with 3-circle goniometer and CCD detector op-
erating at -54 °C. The data collections nominally covered
a hemisphere of reciprocal space utilizing a combination
of three sets of exposures, each with a different F angle,
and each exposure covering 0.3° in a-'. Crystal decay was
monitored by repeating the initial frames at the end of the
data collection and analyzing the duplicate reflections;
no decay was observed. An absorption correction was
applied utilizing the program SADABS [17].
1.2
g (1.47 mmol) of 7 and 0.15 g (0.13 mmol) of
Pd(PPh3)4 were dissolved in 5 ml of toluene. Adsorptive
filtration of the crude product using n-hexane as mobile
phase yielded 1.05 g (1.3 mmol) of a colorless highly vis-
cous oil. Crystallization from diethylether / hexane gave
0.8 g (0.98 mmol / 88%) of 14 as a colorless solid. -
,3C {'H} NMR (100.63 MHz, CDC13) 6: 14.2 (2JC-Sn =
48 Hz, SiCH(CH3)2), 19.5 C jc-Sn= 18 Hz, SiCH(CH3)2),
Ph3Sn: 127.9 (p-Ph), 128.3 (m-Ph, VSn-c = 42 Hz), 137.5
(o-Ph, 2ySn-c = 38 Hz, V Sn-c = 14 Hz), 140.3 (/-Ph.
'/sn-c = 390/373 Hz, 27sn-c = 43 Hz), Ph2Sn: 127.8 (p-
Ph), 128.45 (m-Ph, V Sn-c = 42 Hz), 138.4 (o-Ph,27Sn-c =
43 Hz, 3/snSn-c
= 15 Hz) 139.2 (/-Ph, ]JSn-c = n.f.
,2/snSn-c = 23 Hz), SiPh: 127.2 {p-Ph), 129.1 (m-Ph),
135.8 (o-Ph, Vsn-c = 18 Hz), n.f. (/-Ph).
3.4. Reaction of 1 with alkynes
A crystal of 7 was sealed in a Lindemann-glass capil-
lary. Data for compound 7 were acquired using a Nonius
Kappa CCD at 291 K. The data collection covered almost
the whole sphere of reciprocal space with 360 frames via
a;-rotation (_l/u; = 1°) at two times 10 s for 7 per frame.
2.5
mmol of 1, 7.5 mmol of alkyne (15: pheny-
lacetylene, 16: methylpropargylether) and 0.05 mmol of
tetrakis(triphenylphosphine) palladium in a solution of
20-25 ml of toluene were stirred for 15 h at 60 °C. The re-
sulting products were purified by filtration over dry silica
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1195
P. Bleckmann et al. ■Synthesis and Reactivity of Novel Bis(stannyl)silanes
Table V. Summary of data collection, structure solution and refinement of compounds 5, 6 and 7.
7
5
6
Formula
Fw
Space group
C4iH44SiSn2
814.24
C3sH36SiSn2
758.14
C2/c
C22H52SiSn2
582.11
I2/a
P2,
9.276(1)
17.236(1)
12.727(1)
109.796(1)
18.9508(3)
10.8160(1)
28.5569(3)
100.998(1)
18.4027(4)
8.0742(2)
24.0194(5)
108.115(1)
a [A]
b[A]
c[A]
ß
[deg]
1914.6(3)
2
V [A3]
Z
dcaic. [g/cm3]
Lin. abs. coeff. [mm-1]
T[K]
5745.86(12)
8
1.346
1.784
86
3392.07(13)
4
1.412
1.362
293(1)
1.485
1.532
86
5.2-56.5
8621
411
3.6-56.7
4126
186
29 Range, [deg.]
Indep. refl.
No. parameter
2.9 -50
5021
231
0.0458,0.1025
0.0274, 0.0492
R 1, wR2 (all data)
R\,wR2 (> 2s)
0.0644, 0.1054
0.0446, 0.0977
0.0264, 0.0543
0.0217,0.0515
R\= |IF0I- IFJ| / IF0I; wR2 = I {(F„)2- (Fc)2}2/ w{(F0)2}2.
the respective occupancies. A set of restraints was applied
to aid in modeling the disorder [18], Further details about
the refinements and how disorder was handled are out-
lined in the Supporting Information. Details of the data
collections and refinements are given in Table V, selected
bond lengths and angles are given in Table IV. Full de-
tails for the structural analysis have been deposited with
the Cambridge Crystallographic Data Centre, CCDC No.
132 617 for compound 5, CCDC No. 132 618 for com-
pound 6, CCDC No. 133 131 for compound 7 and are also
available in CIF format from the authors.
In all cases graphite monochromated MoKa radiation
(A = 0.71073 A) was employed. The crystal structures
of the compounds were solved by Direct Methods, as in-
cluded in the SHELX program package [18] (5, 6) and
SHELXS97 [19] (7). Missing atoms were located in sub-
sequent difference Fourier maps and included in the re-
finement. The structures of all compounds were refined
by full-matrix least-squares refinement on F2 (SHELX-
93 [20] (5, 6) and SHELX97 [21] (7)). Hydrogen atoms
at the tin atoms in 5 and 6 were located in a difference
map and included in the refinement using distance re-
straints and UiSo at 1.2 Ueq of the carrier tin atom. All
other hydrogen atoms were placed geometrically and re-
fined using a riding model, including free rotation about
C-C bonds for methyl groups with UjS0constrained at 1.2
for non-methyl groups, 1.5 for methyl groups times Ueq
of the carrier C atom for 5, 6 and a common UiS0 for
aryl (0.095(3) A2), alkyl (0.099(5) A2) for 7. Scattering
factors were those provided with the SHELX program
system. All non-hydrogen atoms were refined anisotrop-
ically. Disorder was handled by including split positions
for the affected groups and included in the refinement of
Acknowledgement
The authors thank the Deutsche Forschungsgemein-
schaft and the Federal State of Northrhine Westfalia for
financial support. We also thank ASV-innovative Chemie
GmbH (Bitterfeld, Germany) and Sivento Chemie GmbH
(Rheinfelden, Germany) for gifts of silanes. We are grate-
ful to Prof. Dr. K. Jurkschat, the NSF (CHE 95-27899),
W. M. Keck Foundation and Syracuse University for
support.
[3] B. L. Chenard, C. M. Van Zyl, J. Org. Chem. 51,
3561 (1986).
[1] H. Schumann, I. Schumann in “Gmelin Handbook
of Inorganic and Organomet. Chemistry”, 8th Edi-
tion, Sn-Organotin Parts 20, Springer Verlag, Berlin
(1993).
[4] M. Murakami, Y. Morita, Y. Ito, J. Chem. Soc.,
Chem. Commun. 428 (1990).
[5] K. Ikenaga, K. Hiramatsu, N. Nasaka, S. Mat-
sumoto, J. Org. Chem. 58, 5045 (1993).
[2] T. N. Mitchell. R. Wickenkamp, A. Amamria,
R. Dicke, U. Schneider, J. Org. Chem. 52, 4868
(1987).
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P. Bleckmann et al. ■Synthesis and Reactivity of Novel Bis(stannyl)silanes
1196
[6] F. Uhlig, C. Kayser, R. Klassen, U. Hermann,
L. Brecker, M. Schürmann, U. Englich. K. Ruh-
landt-Senge, Z. Naturforsch. 54b. 278 (1999).
[7] U. Hermann, M. Schürmann. F. Uhlig, J. Organo-
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[8] J.-P. Quintard, M. Pereyre in Reviews on Silicon,
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[9] M.-F. Connil, P. Jousseaume, M. Pereyre, Organo-
metallics 15. 4469 (1996).
[10] SPARTAN version 4.0; Wavefunction, Inc.; 18401
Von Karman Ave., #370; Irvine, CA 92715 USA;
Nusair [13] with Becke’s nonlocal exchange cor-
rection [14] and Perdew's nonlocal correlation
correction [15] including scalar relativistics (see
[lid] and references therein). The inner core
shells up to 2p for Si, 4d for Sn and Is for C
were treated within the frozen-core approximation
[lid].
[13] S. H. Vosko, L. Wilk, M. Nusair, Can. J. Phys. 58,
1200(1980).
[14] A. D. Becke, Phys. Rev. A 38, 3098 (1988).
[15] J. P. Perdew, Phys. Rev. B 33, 8822 (1986).
[16] H. Hope, Progr. Inorg. Chem. 41, 1(1994).
[17] G. M. Sheldrick SADABS, Program for Absorption
Correction Using Area Detector Data, University of
Göttingen, Germany (1996).
©
Wavefunction, Inc.
[11] a) ADF 2.3.0, Theoretical Chemistry, Vrije Univer-
siteit, Amsterdam;
b) E. J. Baerends, O. E. Ellis, P. Ros, Chem. Phys.
2,41 (1973);
c) G. te Velde, E. J. Baerends. J. Comp. Phys. 99,
84(1992);
[18] SHELXTL-Plus, Program Package for Structure So-
lution and Refinement, Siemens, Madison, Wiscon-
sin (1996).
[19] G. M. Sheldrick, Acta Crystallogr. A46,467 (1986).
[20] G. M. Sheldrick, SHELX-93, Program for Crystal
Strucure Refinement, University of Göttingen, Ger-
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[12] For the density functional calculations we
used the ADF basis set IV and the local
exchange-correlation function by Vosko, Wilk and
[21] G. M. Sheldrick, SHELX-97, University of Göt-
tingen, Germany.
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