Theoretical Study on the silaaromatics Speaker: Xuerui Wang Advisor : Jun Zhu Dec. 23. 2013 B ent's R ule A rom aticity A rom aticity B ent'rule Si O R X Si R O X G = -28.5 ~ 122.2 kcal m ol -1 pentalyne metallapentalyne metallasilapentalyne III A ntiarom atic Arom atic Arom atic II I [M] Si [M] ?
Theoretical Study on the silaaromatics. Speaker: Xuerui Wang Advisor : Jun Zhu Dec. 23. 2013. Outline. [1,3]- substituent Shift for the Formation of the Silabenzenes. 1. 1. 2. The aromaticity of metallasilapentalynes. 3. 3. Summary and Future work. Background. - PowerPoint PPT Presentation
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Theoretical Study on the silaaromatics
Speaker: Xuerui WangAdvisor : Jun Zhu
Dec. 23. 2013
Bent's Rule Aromaticity
AromaticityBent' rule
SiO
RX
SiR OX
G = -28.5 ~ 122.2
kcal mol-1
pentalyne metallapentalyne metallasilapentalyne
III
Antiaromatic Aromatic Aromatic
III
[M] Si[M]?
Outline
11
3
[1,3]- substituent Shift for the Formation of the Silabenzenes
2
2
3 Summary and Future work
The aromaticity of metallasilapentalynes
3
Si
Ad
OTMS
TMS
TMSSi
Ad
OTMSTMS
TMS
hv
TMS = SiMe3
Ad = 1-adamantyl
Figure 1.Photochemically Induced [1,3]-Trimethylsilyl Shift from Si to O Applied by Brook et al. to the Formation of the First Silene Stable at room temperature1. Brook, A. G.; Abdesaken, F.; Gutekunst, B.; Gutekunst, G.; Kallury, R. K. J. Chem. Soc., Chem. Commun. 1981, 191. 2. Brook, A. G.; Nyburg, S. C.; Abdesaken, F.; Gutekunst, B.; Gutekunst, G.; Krishna, R.; Kallury, M. R.; Poon, Y. C.; Chang, Y. M.; Wong-Ng, W. J. Am. Chem. Soc. 1982, 104, 5667.
SiSiO
R3SiR3Si
R''R' R' R''
R'''R'''
OSiR3R3Si
R = Me or iPr
R' = H, Me, Et, iPr, tBu, OSiMe3
R'' = H, Me, Et, iPr, tBu
R''' = H, Me, tBu
Rouf, A. M.; Jahn, B. O.; Ottosson, H. Organometallics.2013, 32, 16.
Figure 2. Synthetic route to silabenzenes through the [1,3]-Si O TMS shift by Density functional theory (DFT) calculations
G= -11.1~ -22.6 kcal mol-1
G = 0.6 kcal/molSi SiO OSiMe3Me3Si
Me3SiMe3Si
nonaromatic six membered ring
driving force
Aromaticity
silicon atom is reluctant
to participate in bonding
Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984, 23, 272.
Background
1.928
1.481
1.346
1.472
1.343
1.8671.796
1.391
1.397
1.396
1.393
1.770
1.934
1.482
1.346
1.474
1.344
1.8671.796
1.389
1.3971.397
1.394
1.775
SiSiO
H3SiH OHH3Si
G = -0.3SiSi
OH3Si
Me2N ONMe2H3Si
G = +46.8
a b
A1 A1' A2'A2
4
Bent’s rule : atomic s character tends to concentrate in orbitals that are directed toward electropositive groups and atomic p character tends to concentrate in orbitals that are directed toward electronegative groups.
(a) Bent, H. A. Chem. Rec.1961, 61, 275. (b) Zhu, J.; Lin, Z.; Marder, T. B. Inorg.Chem. 2005, 44, 9384.
silicon atom is reluctant to participate in bonding sp3
Results and Discussion
5
Results and Discussion
Figure 3. [1,3]-substituent shift for the formation of silabenzenes with various substituents .
SiOXH3Si
SiH2Si OX
X = H ISE = -25.3
X = NMe2 ISE = -28.3
NICS(0)zz -11.2 (X = H) -11.6 (X=NMe2)
Evaluate Aromaticity : ISE(isomerization stabilization energy) method and NICS( nucleus independent chemical shift) calculations
SiSiO
R1
X OXR1
X: H, NMe2, F, OMe, Cl, SMe, Me, GeH3, SiH3, AlH2Set A: R1 = SiH3, Set B: R1 = Me
6Figure 4.Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds.
Results and Discussion
7
Results and Discussion
Figure 5. The plot of s character of Si to the Si-X σ bond vs reaction barriers (ΔG)
8
Results and Discussion
Figure 6. Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds by replacing the acyl group with methylene group in acylsilane..