Transcript Results and Discussion

Theoretical Study on the
silaaromatics
[M]
I
pentalyne
Antiaromatic
[M] Si
?
II
metallapentalyne
Aromatic
III
metallasilapentalyne
Aromatic
Speaker: Xuerui Wang
Advisor : Jun Zhu
Dec. 23. 2013
Outline
1
[1,3]- substituent Shift for the Formation
of the Silabenzenes
2
The aromaticity of metallasilapentalynes
33
Summary and Future work
2
Background
driving
force
Aromaticity
silicon atom
is reluctant
to participate
in  bonding
Kutzelnigg, W. Angew. Chem.,
Int. Ed. Engl. 1984, 23, 272.
3
Results and Discussion
silicon atom is reluctant to
participate in  bonding
sp3
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.
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Results and Discussion
Evaluate Aromaticity : ISE(isomerization stabilization energy) method and
NICS( nucleus independent chemical shift) calculations
NICS(0)zz
-11.2 (X = H)
-11.6 (X=NMe2)
Figure 3. [1,3]-substituent shift for the formation of silabenzenes with various substituents .
5
Results and Discussion
Figure 4.Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds.
6
Results and Discussion
Figure 5. The plot of s character of Si to the Si-X σ bond vs reaction barriers (ΔG)
7
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..
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Results and Discussion
Silabenzene (X) ΔG
ΔG'
ΔG'-ΔG
A1' (H)
-0.3
27.6
27.9
A2' (NMe2)
46.8
74.8
28.0
A3' (Me)
17.8
46.1
28.3
A4' (SMe)
38.1
67.0
28.9
A5' (Cl)
77.2
105.9 28.7
A6' (OMe)
84.8
114.0 29.2
A7' (F)
117.8 147.4 29.6
A8' (GeH3)
-0.8
26.8
27.6
A9' (SiH3)
-16.1
12.5
28.6
A10' (AlH2)
-29.3
-2.2
31.5
B1' (H)
2.3
32.9
30.6
B2' (NMe2)
54.5
83.9
29.4
B3' (Me)
22.3
51.1
28.8
B4' (SMe)
42.4
73.3
30.9
B5' (Cl)
81.5
114.1 32.6
B6' (OMe)
90.2
121.8 31.6
B7' (F)
122.2 153.8 31.6
B8' (GeH3)
0.1
30.0
29.9
B9' (SiH3)
-14.8
15.6
30.4
B10' (AlH2)
-28.5
-0.2
28.7
Figure 7. Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds
in nonaromatic system.
9
Results and Discussion
Figure 8. Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds in
the osmasilabenznes.
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Summary
1. The contribution from aromaticity can be evaluated
quantitatively (ca. 30 kcal/mol) in such rearrangement .
2. Bent's rule plays an important role in both the
thermodynamics and kinetics of the rearrangement .
3. Our findings could be a useful guide to the synthesis of
silabenzenes.
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Outline
1
[1,3]- substituent Shift for the Formation
of the Silabenzenes
2
The aromaticity of metallasilapentalynes
33
Future work
12
Background
[M]
I
pentalyne
Antiaromatic
8e
?
II
III
metallapentalyne
Aromatic
Introduce a metal 10e
116 °
distorted triple
bond
extremely strained
[M] Si
129.5 °
reduce the ring
strain significantly
metallasilapentalyne
Aromatic
silicon atom is reluctant
to participate in 
bonding
Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984, 23, 272.
Zhu, C.; Li, S.; Luo, M.; Zhou, X.; Niu, Y.; Lin, M.; Zhu, J.; Cao,
Z.; Lu, X.; Wen, T.; Xie, Z.; Schleyer, P. v. R.; Xia, H. Nat. Chem.
2013, 5, 698.
13
Results and Discussion
The aromaticity of metallasilapentalynes
Ring A;
Ring B:
NICS(0) = - 7.3
NICS(0) = - 8.9
NICS(1) = - 9.8
NICS(1) = - 8.8
NICS(2) = - 5.9
NICS(2) = - 4.1
NICS(-1) = - 10.0 NICS(-1) = - 9.1
NICS(-2) = - 6.2
NICS(-2) = - 4.2
NICS(1)zz = - 19.8 NICS(1)zz = - 16.2
Figure 9. The optimized structure 、the ISEs values of the osmasilapentalynes and the NICS values of the
each ring
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The effect of ligand
The effect of base
The ring strain
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Summary
1. From the view of negative ISEs and negative NICS
values compared to benzene both reveal aromaticity in
osmasilapentalyne.
2. osmasilapentalyne prefer -donor ligands than accepter ligands.
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Outline
1
[1,3]- substituent Shift for the Formation
of the Silabenzenes
2
The aromaticity of metallasilapentalynes
3
3
Future work
17
Future work
1. Theoretical study on the [1,3]- substituent shift for the formation of the
stannumbenzenes and germaniumbenzene.
2. Tune the metal center by other transition metals.
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pesticide
Organophosphorus
compounds
medicine
antibacterial agents
enzyme inhibitors
flame retardant
anti HIV agents
19
19
Condition Optimization
？
Entry
initiator
eq
solvent
T(oC)
t[h]
NMR yield
[%]
1
Mn(OAc)3
2.2
HOAc
80
12
15
2
Mn(OAc)3
2.2
DMF
80
12
5
3
Mn(OAc)3
2.2
THF
80
12
trace
4
AgNO3
0.5
DMF
80
12
trace
5
AIBN
1.2
THF
80
12
trace
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致谢
• 感谢朱军老师在学习、生活等各方面给予的关心与指导!
• 感谢赵玉芬老师、特别要感谢唐果老师、高玉珍师姐、许
健师兄、张鹏波、吴巨在实验上的悉心指导和帮助!
• 感谢实验室的范景兰师姐、黄莹师姐以及其他同学的热心
帮助！
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• Thank you for your attention！
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