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Microwave spectra of the αd3- and 29Si-phenylsilane isotopic species
Volinic . .
38, number
CHEMICAL
2
MICKOWAVE SPECTRA OF THE ad,-
PHYSICS
I March 1976
LETTEKS
AND 2%LPHENYLSILANE
ISOTOPIC
SPECIES
W. CAMINATI and G. CAZZOLI Laboratorio di Spcttroscopia Afaiccolar~ dcl C.N.K., 40126 Bologna, Italy and Istituto C~~i~nico“G Ciatnician “, U.viwrsity of Bologna, 40126 Bologna. Italy Received
13 October
I!)75
Tbc microwave rotational spcctrn of lydJ-pbcnylsilanc nnd of zgSi-phcnylsilanc of the lowering of the barrier to internal rotation with trideutcration was obtained. used to obtain n partial substitution structure of the top.
The microwave spectrum of the most abundant species of ph2ny:silanc has been reported earlier [ 11 and the potential barrier to internal rotation vh = 17.23 cal/mo!e was obtained. Sevornl low sixfold barriers. in light top molecules, have been studied by microwave spectroscopy [ l--8],
but
Only
in a few cases [2,9,10], Wilerc tllC tOi1 was a
methyl goup, the isotopic species with the trideuterated top have been studied. About a 15% reduction of v6 upon top deutcrritior. was ObScrVcd. The spcctrurn of C6H5-SiD, was aralyzed in order to investigate the effect of deutcration in the case of the silyl group. The matrixelements relevant to this type of low barrier problem (where only one internal dcgrcc of freedom is allowed) have been discussed elsewhere [ 1 I- 131. As Ognta outlined [ 131, passing from a value of the rcduccd barrier heights of0.041 (CII3NO2) to a value ofs = 4.58 (CF3N02) the spectrumcllangcs drasticaily and correspondingly the enerm level calculation bccomcs more complicated because the van Vleck transformation [J 11 is not possible. But although the value of s in the case of CgH5SiD3 is 0.393, the m = 0 spectrum follows an effectively rigid rotor pattern so that we could use the Cll,BF, model [ 111. artis-phcnylsilnnc was prepared in the same way as the norrr& spccics s doscribed in roi. [ 141 but using LiAlD4 instead of LiAIH,. The microwave spectra wcrc obtained with an IL?MRR 8400 C type spectrometer. The cell was coelec!
218
have been mensnred. A confirmation Tbc rotational constants have been
to approximately -50°C. A typical “a” type band spectrum was found, but the intensity of the C6H5-SiD3 bands is larger than
that of the C6H5-SiH3
bands because the nuclear
of the 112f 0,311 lirics arc more favourable in the case ofC6H5-SiD,. On the other hand the
spin weights
m = 0,311 lines arc weaker than those of CGH; -SiH3. In fact the classification of the nuclear spin functions of the tops in the Dstl symmetry group [ 151 leads to the ratio 4 : 2 bctwecn the A nnd B species for SiH3 and to tllc ratio 11 : 8 in the case of SiD3. On the other hand the E and A spin functions can combine with the rn + 0,311 and m = 0,3rz torsional wnvefunc-
tions respectively. In table 1 the cxpcrimental
and the calculated frcquencies for the I?Z= 0 lines of C6H,SiD, are listed. It can be seen that the spectrum follows an effcctively rigid rotor pattern within expcrimcntal accuracy. In table 2 are listed the frequencies of the llnl = 3 lines. The usual discrepancy between the caiculated and experimental frequencies, due to the lack of a quantitative treatment of tile vibration-rotation interaction is observed. In tab!e 3 the molecular constants of ad3-phenylsilane are reported. The inertial defect and the rotationai constant il’ vary upon cz-deutcraiion’in the same BU~SCx for tolucne [6,10].
The decrease in V, with dcuteration parallels the similar dccrcasc observed for other molecules, as shown in table 4. It is probably
due ?o a change in the
Volume 38, number 2
CCIEhiICAL PHYSICS LE?TEKS
values d~t~rrn~ff~d with A’ = 5700.23, Er = 1388.993, C = 1116.559. Conshn‘ts and frcquen-
C’~f15--SiD3 m = 0 tines. Glcukttcd
ties in MHz A_ -.___.__---_
_.._.. - __._-_ - .-__-
- ..-_- --
------_.-.
-
-
._-
-
k,
Frcgucncies -~_.--*
._...._
__
-
- . ._. ._
_..___.
303 -’ 40.1
iOf3S.82
404 -’ ~05 413 -*514
12285.27
%M - 625 6 06 -+ 707 616 -+ 717
16442.57
lG442.53
6f4 -+ 7~~
18068.74
18068.72
625 - 726 I. --_ .__.-. -.-
Transition
17441.91 17441.94 - -. -- ._ __I._ _“._._ . .. - -_ -_ ._ -_ _I..._- _ .- ._ --...
4--s
5-G
6+7 ~__c_----_--
--._.-+-
Frequencies _--_____-.-_ _ _I__ oiilc. cxpti. ._ -. -. _-- __ -- --- --9596.08 95xi.71
-c
10437.79 10476.27
10439.27 10475.23
-_ ++ -F-
ff390.57 12086.70 13041.85
11991.21 12085.40
-+
13124.42
13124.40
-+f f-+
i4381.95 14566.23 15642.48 15719.77
14382.81 r45i53.95 15644.61
-i+
16470.12 16771.17 171390.46 f7086.35 - -..- ._ I__- -_-,____
13043.81
15789.09
zero-point vibration of the top (particularly the sy~umetrica H--Z% -11 tending mode) as suggested in ref. EA. We were able to identify several lines of 29Siphcnylsilsnc in natural abundance (4.7%) by the mi-
-0.02
0.06 0.02 0.00 - 0.02
14125.59
616
Tiiblc 3 C&HS-+S~DJ molecular --_-_
-C&k.
-. --_--_-----.-
-0.16 0.05 0.09 -0.01 0.02 -0.09 -0.03 0.01
15388.16 14977.12 1692 1.08
-+ 624
-
I__ ..----
-_I)____-_.-.---.--_
exptt.-
9898.70
14 125.65
-
523
___.-._ .-_
10335.98 12285.22 13150.26 11795.60 12742.45 12499.97 14621.96 15740.26
15388.18 i4977.12 169 1 I.06
515
mined with A’ = 5700.2.13 = 13(38.993, C: I! 16.55, F * 48377, V6 = 166985. Constants and frequencies in MHz ~.-__-._____----_~.--.-- -._--
_.__.
__-__
-. -_-..-__-_..--..--.-.-.
13150.35 L279.5.59 12742.47 12499.88 1462X.93 157.W.27
Table 2 C6H5--SiI& frnl = 3, fkl = I lines. C~~~~~t~~ivaiucs ckter-
f+J+i ____ 3 -9 4
___C3IC.
9898.68
3213422
414-+5iS 422 - 523 423 - 524 505 -+ 60s 5;u-*615
____ __-.- - -.-.
-
CXpti.
-*Jk_r,q,
.-.-_..-
.._ _ .___ _. ___ ______._..____.. _.__.-_-_.-
.- .-. - - ..-_._ -
‘fkmsition kl,
1 Ma&t976
0.04
0.02 -0.03 -.-.-.-.--.-.-e--
constants
----.--_-
n--.y--.-_-2~
-.
A’ ,: cs700.2 f 0.9) hiffz
B = (1388.993 2 0.005) htltlz C’
= (I 116.559 c WOS)
hftfz
E;r
-0.88 1128 A =I,--f&--Ii= 0.110 amu A* F r: 48377 hffiz (ussumcd) I
v, = 166985 hfil7. = Wi.93 * 0.03) cti/rnoIe _- --. - .-.. - .- “_.__.__._.___~ .._.._-.__--___-___
crowave-radiofreq~tericy double rcsona~ce by pumping some K doublers; afterwards,
tectmique some other
lines could be measured with ihe conventional Stark spectrometer. The corresponding frequencies are reported in tablf: 5. We ffied A’ at the value of tile C6H5SiH3 constant (this is justified by the very small vflriatinn of the A’ constant in the analogous isotopic species of toiuenc) and so we could obtain very precise v;?lues of the rotational constants B and C, which are reported in table 6 together with the Zsi coordinate. Following the method used by Kreiner et al. [IO] who utilized a formula identical to tftat derived. by Chutj&m [ 161 for m&ipfe. substitution in a molecule of overalf C,, symmetry we calculated zR of the silyl 219
Vu!umc 38, nilmbcr :! -
Table4 V, barrier
1 hIarch 1976
CHEMICAL PHYSICS LETTEKS
_ reduction passing from an -XII3 to an -XD3 .__-___._- . ..- _.___..._ -_. -._._--_-....--_
bIoleculc
top ._.-._
. . ._
-...-__- _..------
V, (cul/molc)
-----.
-XHs top -XD3 top __________________ ____ ____._---.--___-._.-..-.----.
-
6.03 CHjBF7_ 13.77 t01ucns 13.94 pllenylsiianc 17.82 ____--_-_--__--_--.----_--._-.
_______
Table 5 C,Hs-2gSiH~
m = 0 lines. Callculatcd
_
_ .__ ___-..__
13.9 12.0 IS.4 10.7
._- .--- _.___ -.__-.._-_-_---_
v:~lucsd~t~~rrnined
ties in hIHz _._.___ _-__. _____ ______--._.-_ .- _._.-___---.--. Transition
--.-.
5.19 12.12 21.79 15.92
nitromethane
with A’ = 5703,
_.
B = 1475.637.
.-_-.-------.-Frequcncius ___ .__._ _..___.__ -__-__-_
tXpU. _-__-._ .
-I’ k’+1 __. -.-.__ - .._.. .._.___ -_- .. .._ -___-_
----
CA. _ __-._------.__-
1x91 16,101 : 11, this work
- -.-.
C=
_.-. -
1172.056.
--*
917
-r ~a10
247413.00
24747.110
945
+
26691.64 29413.40 29368.22 34701.16
2669 1.93 29413.33 29367.94 34701.35
-0.29 0.07 0.28 -0.19
34GV3.38 37487.62
34693.45 37487.7 1
-0.07 -0.09
37417.11
37417.25
1046 1047
1046
-
1147
+
lhl3
125, + 1358 1258 -’ 1359 13410+ 14.-.11 13.58 -* l+!, 1359
-
--------.-.-._.
ia!;10
_- -._---_-_..-._.
_
.--
22057.26 24934.22
37401.57 37401.65 ._ ___._.--_ .-_------.--._
.-._ - _---
uxptl.-AC. --_-..---
826
&!6
and ircqucn-
_-- _- .__.-- -_-.- ._--
909
+
Constants
- __----.-.
-. 22057.39 34934.63
725
._. ---
121
._ .
Jk_,,k+I -Ji
._. ._. -..... ..--
Ref.
fb reduction
.-.
---
----
0.13 0.4 1 0.20
-0.14 -0.08 .____ _._ _____.____ _~____
hydrogen atoms from the following expression Table 6 ChHs- 2gSi113 uz = 0 molecular tion coordinate _______________--
constants _._.__-
and
ZSi
substitu-
-_..---
where y = 3Anr fiI/(hf + 3Am) is the “reduced mass” for tridcutcration and Al, = Iti (SD,) -iLy (SiH3) was calculated assuming 1.39
A’
= 5703. h1f-k (assumed) B = (1475.637 k 0.010) hli-lz C = (1172.056 + !J.OlO) MHz A’
= -0.865996
Zsi =
---
I+ I = [(A& - ; A~,)/P] “* ,
2.3495 * 0.0010 A ________--_.
rncdiate Table 7 Sibyl group geometry
-.-.-.-_
__..._ -
YI I ass (A\) I,(SiDs) (arnu X2) c’H (A) L (II-Si-H) r (Si-H) (A) _-_A-
220
dcrivcd
from Ssi, ~11 andy
,.____ -_-1.39 11.67 2.854 108”58’ 1.479 _-
11 (assunxd)
_--
_._--_1.41 12.01 2.849
109” 25’ 1.496 ..- _-__--
character
if compared
with
the ctlaracters
the corresponding
of
sp and sp3 hybridized bond in SiH3-m-H and SiH3-CH3 respectively. In table 7 the silyl group geometry obtained from these assumption and the r,-located Z&position has been reported. iye wish to express our appreciation to Professor A.M. Mirri for discussions of this work.
Volume 38, number 2
References
[9] 3-E. NoIhb, Kwi
[l] W. Caninati,
G. Cazzoli and A.M. Mirri, Chcm. Phys. Letters 35 (1975) 475. [2] E. Tanncnbaum, R.J. Myers and W.13. i&inn, 5. Chem.
Phys 25 (1956) 42. 13 j R.E. Nayior Jr. and E.B. Wilson Jr., J. Ckcm. Yhys. 26 (19.57) 1057. (41 H.n. Rudolph and fi. Se&r, Z. ~atur~orsci~. 204 (1965) 1682. [Sf GE. ffcrberich, 2. Naturforscb. 22a (1967) 761. [6] 1i.D. Rudolph, Il. Drcider, A. Jncschke and P. Wcndliny. 2. Naturforsch. 223 (1967) 940. 17 ] H.D. Kudoipit, H. Drcizler and if. Scilcr, Z. Naturforsch. 22n (1967) 1738. [SJ W. Caminali, Ci. Carmli and A.M. hiitri, Churn. Pi-tys.
Letters 31(1974)
1 March 1976
CHEMICAL PIIYSICS LETTERS EA. Rinehart,
P.B. Rekdtart
and R.R.
Jr., J. Chcm. Phys. 55 (1971) 1998. Kreiner, H.D. Rudoipb and B.T. ‘fan, J. bioi. Spcc-
flO] W.A. try. 48 (1973) 86. [lil E.B. Wilson Jr., C.C. Lin and EAR: Lidc, J. Cltem. Phys. [12J
23 (1955) 136. CC. Lin and I.D. Swakn.
Rev. Mod. Phys. 31 (1959)
841. [ 131 T. Ogatn, J. Mol. Spcctry. 54 (1975) 275. fl4] Inorg. SynQ. XI !I9681 161. [ISI J.C. Longuct-Higgins, Rloi. Phys. 6 (1963) 445. [I61
A. Chutjian, J. Mol. Spectry. 14 (1964) 361. f17] M.C.L. Gerry and T-M. Sugden, Tcans. tzaraday Sot. 61
(1965) 2091. [ 181 R.W. Kilb and L. Picrcc, 3. CBem. Phys. 27 (13.57) 108.
104.
221
38, number
CHEMICAL
2
MICKOWAVE SPECTRA OF THE ad,-
PHYSICS
I March 1976
LETTEKS
AND 2%LPHENYLSILANE
ISOTOPIC
SPECIES
W. CAMINATI and G. CAZZOLI Laboratorio di Spcttroscopia Afaiccolar~ dcl C.N.K., 40126 Bologna, Italy and Istituto C~~i~nico“G Ciatnician “, U.viwrsity of Bologna, 40126 Bologna. Italy Received
13 October
I!)75
Tbc microwave rotational spcctrn of lydJ-pbcnylsilanc nnd of zgSi-phcnylsilanc of the lowering of the barrier to internal rotation with trideutcration was obtained. used to obtain n partial substitution structure of the top.
The microwave spectrum of the most abundant species of ph2ny:silanc has been reported earlier [ 11 and the potential barrier to internal rotation vh = 17.23 cal/mo!e was obtained. Sevornl low sixfold barriers. in light top molecules, have been studied by microwave spectroscopy [ l--8],
but
Only
in a few cases [2,9,10], Wilerc tllC tOi1 was a
methyl goup, the isotopic species with the trideuterated top have been studied. About a 15% reduction of v6 upon top deutcrritior. was ObScrVcd. The spcctrurn of C6H5-SiD, was aralyzed in order to investigate the effect of deutcration in the case of the silyl group. The matrixelements relevant to this type of low barrier problem (where only one internal dcgrcc of freedom is allowed) have been discussed elsewhere [ 1 I- 131. As Ognta outlined [ 131, passing from a value of the rcduccd barrier heights of0.041 (CII3NO2) to a value ofs = 4.58 (CF3N02) the spectrumcllangcs drasticaily and correspondingly the enerm level calculation bccomcs more complicated because the van Vleck transformation [J 11 is not possible. But although the value of s in the case of CgH5SiD3 is 0.393, the m = 0 spectrum follows an effectively rigid rotor pattern so that we could use the Cll,BF, model [ 111. artis-phcnylsilnnc was prepared in the same way as the norrr& spccics s doscribed in roi. [ 141 but using LiAlD4 instead of LiAIH,. The microwave spectra wcrc obtained with an IL?MRR 8400 C type spectrometer. The cell was coelec!
218
have been mensnred. A confirmation Tbc rotational constants have been
to approximately -50°C. A typical “a” type band spectrum was found, but the intensity of the C6H5-SiD3 bands is larger than
that of the C6H5-SiH3
bands because the nuclear
of the 112f 0,311 lirics arc more favourable in the case ofC6H5-SiD,. On the other hand the
spin weights
m = 0,311 lines arc weaker than those of CGH; -SiH3. In fact the classification of the nuclear spin functions of the tops in the Dstl symmetry group [ 151 leads to the ratio 4 : 2 bctwecn the A nnd B species for SiH3 and to tllc ratio 11 : 8 in the case of SiD3. On the other hand the E and A spin functions can combine with the rn + 0,311 and m = 0,3rz torsional wnvefunc-
tions respectively. In table 1 the cxpcrimental
and the calculated frcquencies for the I?Z= 0 lines of C6H,SiD, are listed. It can be seen that the spectrum follows an effcctively rigid rotor pattern within expcrimcntal accuracy. In table 2 are listed the frequencies of the llnl = 3 lines. The usual discrepancy between the caiculated and experimental frequencies, due to the lack of a quantitative treatment of tile vibration-rotation interaction is observed. In tab!e 3 the molecular constants of ad3-phenylsilane are reported. The inertial defect and the rotationai constant il’ vary upon cz-deutcraiion’in the same BU~SCx for tolucne [6,10].
The decrease in V, with dcuteration parallels the similar dccrcasc observed for other molecules, as shown in table 4. It is probably
due ?o a change in the
Volume 38, number 2
CCIEhiICAL PHYSICS LE?TEKS
values d~t~rrn~ff~d with A’ = 5700.23, Er = 1388.993, C = 1116.559. Conshn‘ts and frcquen-
C’~f15--SiD3 m = 0 tines. Glcukttcd
ties in MHz A_ -.___.__---_
_.._.. - __._-_ - .-__-
- ..-_- --
------_.-.
-
-
._-
-
k,
Frcgucncies -~_.--*
._...._
__
-
- . ._. ._
_..___.
303 -’ 40.1
iOf3S.82
404 -’ ~05 413 -*514
12285.27
%M - 625 6 06 -+ 707 616 -+ 717
16442.57
lG442.53
6f4 -+ 7~~
18068.74
18068.72
625 - 726 I. --_ .__.-. -.-
Transition
17441.91 17441.94 - -. -- ._ __I._ _“._._ . .. - -_ -_ ._ -_ _I..._- _ .- ._ --...
4--s
5-G
6+7 ~__c_----_--
--._.-+-
Frequencies _--_____-.-_ _ _I__ oiilc. cxpti. ._ -. -. _-- __ -- --- --9596.08 95xi.71
-c
10437.79 10476.27
10439.27 10475.23
-_ ++ -F-
ff390.57 12086.70 13041.85
11991.21 12085.40
-+
13124.42
13124.40
-+f f-+
i4381.95 14566.23 15642.48 15719.77
14382.81 r45i53.95 15644.61
-i+
16470.12 16771.17 171390.46 f7086.35 - -..- ._ I__- -_-,____
13043.81
15789.09
zero-point vibration of the top (particularly the sy~umetrica H--Z% -11 tending mode) as suggested in ref. EA. We were able to identify several lines of 29Siphcnylsilsnc in natural abundance (4.7%) by the mi-
-0.02
0.06 0.02 0.00 - 0.02
14125.59
616
Tiiblc 3 C&HS-+S~DJ molecular --_-_
-C&k.
-. --_--_-----.-
-0.16 0.05 0.09 -0.01 0.02 -0.09 -0.03 0.01
15388.16 14977.12 1692 1.08
-+ 624
-
I__ ..----
-_I)____-_.-.---.--_
exptt.-
9898.70
14 125.65
-
523
___.-._ .-_
10335.98 12285.22 13150.26 11795.60 12742.45 12499.97 14621.96 15740.26
15388.18 i4977.12 169 1 I.06
515
mined with A’ = 5700.2.13 = 13(38.993, C: I! 16.55, F * 48377, V6 = 166985. Constants and frequencies in MHz ~.-__-._____----_~.--.-- -._--
_.__.
__-__
-. -_-..-__-_..--..--.-.-.
13150.35 L279.5.59 12742.47 12499.88 1462X.93 157.W.27
Table 2 C6H5--SiI& frnl = 3, fkl = I lines. C~~~~~t~~ivaiucs ckter-
f+J+i ____ 3 -9 4
___C3IC.
9898.68
3213422
414-+5iS 422 - 523 423 - 524 505 -+ 60s 5;u-*615
____ __-.- - -.-.
-
CXpti.
-*Jk_r,q,
.-.-_..-
.._ _ .___ _. ___ ______._..____.. _.__.-_-_.-
.- .-. - - ..-_._ -
‘fkmsition kl,
1 Ma&t976
0.04
0.02 -0.03 -.-.-.-.--.-.-e--
constants
----.--_-
n--.y--.-_-2~
-.
A’ ,: cs700.2 f 0.9) hiffz
B = (1388.993 2 0.005) htltlz C’
= (I 116.559 c WOS)
hftfz
E;r
-0.88 1128 A =I,--f&--Ii= 0.110 amu A* F r: 48377 hffiz (ussumcd) I
v, = 166985 hfil7. = Wi.93 * 0.03) cti/rnoIe _- --. - .-.. - .- “_.__.__._.___~ .._.._-.__--___-___
crowave-radiofreq~tericy double rcsona~ce by pumping some K doublers; afterwards,
tectmique some other
lines could be measured with ihe conventional Stark spectrometer. The corresponding frequencies are reported in tablf: 5. We ffied A’ at the value of tile C6H5SiH3 constant (this is justified by the very small vflriatinn of the A’ constant in the analogous isotopic species of toiuenc) and so we could obtain very precise v;?lues of the rotational constants B and C, which are reported in table 6 together with the Zsi coordinate. Following the method used by Kreiner et al. [IO] who utilized a formula identical to tftat derived. by Chutj&m [ 161 for m&ipfe. substitution in a molecule of overalf C,, symmetry we calculated zR of the silyl 219
Vu!umc 38, nilmbcr :! -
Table4 V, barrier
1 hIarch 1976
CHEMICAL PHYSICS LETTEKS
_ reduction passing from an -XII3 to an -XD3 .__-___._- . ..- _.___..._ -_. -._._--_-....--_
bIoleculc
top ._.-._
. . ._
-...-__- _..------
V, (cul/molc)
-----.
-XHs top -XD3 top __________________ ____ ____._---.--___-._.-..-.----.
-
6.03 CHjBF7_ 13.77 t01ucns 13.94 pllenylsiianc 17.82 ____--_-_--__--_--.----_--._-.
_______
Table 5 C,Hs-2gSiH~
m = 0 lines. Callculatcd
_
_ .__ ___-..__
13.9 12.0 IS.4 10.7
._- .--- _.___ -.__-.._-_-_---_
v:~lucsd~t~~rrnined
ties in hIHz _._.___ _-__. _____ ______--._.-_ .- _._.-___---.--. Transition
--.-.
5.19 12.12 21.79 15.92
nitromethane
with A’ = 5703,
_.
B = 1475.637.
.-_-.-------.-Frequcncius ___ .__._ _..___.__ -__-__-_
tXpU. _-__-._ .
-I’ k’+1 __. -.-.__ - .._.. .._.___ -_- .. .._ -___-_
----
CA. _ __-._------.__-
1x91 16,101 : 11, this work
- -.-.
C=
_.-. -
1172.056.
--*
917
-r ~a10
247413.00
24747.110
945
+
26691.64 29413.40 29368.22 34701.16
2669 1.93 29413.33 29367.94 34701.35
-0.29 0.07 0.28 -0.19
34GV3.38 37487.62
34693.45 37487.7 1
-0.07 -0.09
37417.11
37417.25
1046 1047
1046
-
1147
+
lhl3
125, + 1358 1258 -’ 1359 13410+ 14.-.11 13.58 -* l+!, 1359
-
--------.-.-._.
ia!;10
_- -._---_-_..-._.
_
.--
22057.26 24934.22
37401.57 37401.65 ._ ___._.--_ .-_------.--._
.-._ - _---
uxptl.-AC. --_-..---
826
&!6
and ircqucn-
_-- _- .__.-- -_-.- ._--
909
+
Constants
- __----.-.
-. 22057.39 34934.63
725
._. ---
121
._ .
Jk_,,k+I -Ji
._. ._. -..... ..--
Ref.
fb reduction
.-.
---
----
0.13 0.4 1 0.20
-0.14 -0.08 .____ _._ _____.____ _~____
hydrogen atoms from the following expression Table 6 ChHs- 2gSi113 uz = 0 molecular tion coordinate _______________--
constants _._.__-
and
ZSi
substitu-
-_..---
where y = 3Anr fiI/(hf + 3Am) is the “reduced mass” for tridcutcration and Al, = Iti (SD,) -iLy (SiH3) was calculated assuming 1.39
A’
= 5703. h1f-k (assumed) B = (1475.637 k 0.010) hli-lz C = (1172.056 + !J.OlO) MHz A’
= -0.865996
Zsi =
---
I+ I = [(A& - ; A~,)/P] “* ,
2.3495 * 0.0010 A ________--_.
rncdiate Table 7 Sibyl group geometry
-.-.-.-_
__..._ -
YI I ass (A\) I,(SiDs) (arnu X2) c’H (A) L (II-Si-H) r (Si-H) (A) _-_A-
220
dcrivcd
from Ssi, ~11 andy
,.____ -_-1.39 11.67 2.854 108”58’ 1.479 _-
11 (assunxd)
_--
_._--_1.41 12.01 2.849
109” 25’ 1.496 ..- _-__--
character
if compared
with
the ctlaracters
the corresponding
of
sp and sp3 hybridized bond in SiH3-m-H and SiH3-CH3 respectively. In table 7 the silyl group geometry obtained from these assumption and the r,-located Z&position has been reported. iye wish to express our appreciation to Professor A.M. Mirri for discussions of this work.
Volume 38, number 2
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