3314
R. Shankar, A. Joshi / Journal of Organometallic Chemistry 691 (2006) 3310–3318
Table 2
1H, 13C{1H}, 29Si{1H}/29Si NMR, UV and GPC data of polysilanes
1H NMR (ppm)
d
13C{1H} NMR (ppm)
d
29Si{1H}/29Si NMR
UVa
k
max/e Mw
PDIc
1.78
b
Polysilane
d
(ppm)
1b
1.44 (br, b-/b0-CH2), 0.94 (t,
22.47 (c0-CH2), 21.88 (b-CH2),
6.02 (Et3Si), 0.00
(SiMe3) ꢁ30.03
296/671
4780
3JH–H = 7.6 Hz, CH3–Et + a-/a0- 20.15 (a-CH2), 17.64 (a0-/b0-
CH2), 0.62 (br, c-/c0-CH2), 0.51
(br, CH2–Et), 0.00 (br, SiMe)
CH2), 16.61 (c-CH2), 7.54 (CH3– (br, Si backbone)
Et), 3.46 (CH2–Et), ꢁ1.52 (Si–
Me3)
1c
1d
2b
2c
3.72 (br, CH2–OEt), 1.36 (br, b- 58.86 (CH2–OEt), 21.46 (b-CH2), 5.93 (Et3Si), ꢁ29.89
293/732
3310
2394
2952
3801
1.36
1.41
1.25
1.63
CH2), 1.13 (br, CH3–OEt), 0.85
(br, CH3–Et + a/a0-CH2), 0.54,
0.44 (c-/b0-CH2 + CH2–Et)
20.38 (a-CH2), 19.05 (CH3–OEt), (br, Si backbone),
17.56 (c-CH2), 7.89 (CH3–Et),
6.97, 5.42 (a0-/b0-CH2), 3.12
(CH2–Et)
ꢁ46.25 (Si–(OEt)3)
3.49 (br, SiH3), 1.32 (br, b-CH2), 21.83 (b-CH2), 19.39 (a-CH2),
6.86 (Et3Si), ꢁ30.55 (br, 278/824
Si backbone), ꢁ48.03,
3
0.86 (t, JH–H = 7.6 Hz, CH3–
Et + a-CH2), 0.67 (br, a0-/b0-
CH2), 0.55 (br, c-CH2), 0.44 (br, 1.02 (b0-CH2)
CH2–Et)
17.20 (c-CH2), 9.56 (a0-CH2),
7.53 (CH3–Et), 3.44 (CH2–Et),
ꢁ51.28, ꢁ54.52, ꢁ57.76
1
(q, SiH3, JSi–H
=
193.1 Hz)
7.50, 7.28 (br, Si–Ph), 1.42 (br,
b-/b0-CH2), 0.84 (br, a-/a0/c-
CH2), 0.57 (c0-CH2), 0.28 (br,
PhMe2Si), 0.00 (br, SiMe3)
139.42, 133.44, 128.76, 127.73
1.26 (SiMe3)-3.10
299/822
(Si–Ph), 22.35 (c0-CH2), 21.83 (b- (PhMe2 Si)-30.78
CH2), 20.17 (c-/a-CH2), 17.68
(a0-/b0-CH2), ꢁ1.41 (Si–Me3),
ꢁ2.81 (PhMe2Si)
(br, Si backbone)
7.44, 7.25 (br, Si–Ph), 3.73 (br,
CH2–OEt), 1.42 (br, b-CH2), 1.15 (Si–Ph), 58.21 (CH2–OEt), 21.38 (br, Si backbone),
139.39, 133.41, 128.72, 127.68
ꢁ3.18 (PhMe2Si) ꢁ27.23 296/887
(br, CH3–OEt), 0.78 (br, a-/c-/
a0-/b0-CH2), 0.21 (br, PhMe2Si)
(b-CH2), 19.64 (c-CH2), 18.40
(CH3–OEt), 17.62 (a-CH2), 6.65,
4.50 (a0-/b0-CH2), ꢁ2.94
(PhMe2Si)
ꢁ45.35 (Si–(OEt)3)
2d
7.50, 7.35 (Si–Ph), 3.54 (br,
139.24, 133.48, 128.80, 127.74
ꢁ3.15 (PhMe2Si) ꢁ28.67 274/873
2289
1.54
SiH3), 1.42 (br, b-CH2), 0.82 (br, (Si–Ph), 20.30 (b-/c-CH2), 16.90 (br, Si backbone),
a-/c-/a0-/b0-CH2), 0.27
(PhMe2Si)
(a-CH2), 8.76 (a0-CH2), 2.54 (b0- ꢁ48.79, ꢁ52.02, ꢁ55.25,
CH2), ꢁ2.86 (PhMe2Si)
ꢁ58.48 (q, SiH3,
1JSi–H = 192.5 Hz)
0.78 (SiMe3) ꢁ32.46
(br, Si backbone)
4b
4c
4d
7.18 (br, SiPh), 1.10 (br, a0-/b0-/ 136.68, 134.23, 127.46 (Si–Ph),
c0-CH2), 0.00 (br, SiMe)
328/2400
323/2700
314/1500
4002 (2628)d 1.52 (1.32)d
7122 (3505)d 2.05 (1.38)d
2348 (3175)d 1.33 (1.46)d
21.83 (a0-/b0-/c0-CH2), ꢁ1.64
(SiMe3)
7.00 (br, SiPh), 3.46 (br,
CH2–OEt), 1.01 (br, a0-/b0-
CH2 + CH3–OEt)
7.18 (br, SiPh), 3.31 (br, SiH3),
0.81 (br, a0-/b0-CH2)
136.55, 134.16, 127.53 (Si–Ph),
58.06 (CH2–OEt), 18.22 (CH3–
OEt), 5.42 (a0-/b0-CH2)
136.39, 133.77, 127.89 (Si–Ph),
8.69 (a0-CH2), 1.84 (b0-CH2)
ꢁ30.17 (br, Si
backbone), ꢁ46.19
(Si–(OEt)3)
ꢁ32.01 (br, Si
backbone), ꢁ48.51,
ꢁ51.75, ꢁ54.99, ꢁ58.24
1
(q, SiH3, JSi–H
=
193.1 Hz)
a
e units: (Si repeat unit)ꢁ1 dm3 cmꢁ1; kmax units: nm.
Molecular weights determined by GPC relative to polystyrene standards; eluant: THF; 25 °C.
PDI = polydispersity index (Mw/Mn).
b
c
d
Molecular weight of poly (phenysilane) prepared under different runs.
(1H–13C{1H}) NMR spectrum of a representative polysi-
lane 1b (Fig. 4) which shows cross peaks at d 21.88,
17.64/1.44 (b-/b0-CH2), 16.61, 22.47/0.62 (c-/c0-CH2),
20.15, 17.64, 7.54/0.94 (a-/a0-CH2, CH3–Et). A detailed
assignment for other polysilanes has been made accord-
ingly and pertinent spectral data are given in Table 2.
29Si{1H} NMR spectra reveal sharp resonances in the
chemical shift region which are characteristic of appended
silicon moieties. The 29Si{1H} resonances due to silicon
backbone appear at d ꢁ27.23 to ꢁ30.78 showing broad
and featureless profile. For 1d and 2d, the presence of
appended SiH3 group is confirmed by 29Si signal at d
In order to get an insight into the free radical hydrosily-
lation approach, poly(phenylsilane) was also subjected to
chemical modification by AIBN catalyzed reaction with
allyltrimethyl/triethoxyvinyl/trichlorovinylsilane. This has
resulted in the isolation of linear polysilanes 4b–d bearing
phenyl and carbosilyl groups as pendant substituents.
There is no evidence of Si–Si bond cleavage during hydro-
silylation from the GPC data which shows a monomodal
molecular weight distribution with Mw = 2348–7122 and
PDI = 1.33–2.05. IR and 1H NMR spectra of these polysil-
anes suggest the inclusion of 75–85% carbosilyl moiety as
the pendant groups. The presence of residual Si–H groups
in the polymeric framework is evident by a weak IR
1
ꢁ48.03 to ꢁ58.48 (quartet, JSi–H = 192.5–193.1).