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..

9

Silabenzene (X) ΔG ΔG' ΔG'-ΔG

A1' (H)A2' (NMe2)

-0.346.8

27.674.8

27.928.0

A3' (Me)A4' (SMe)A5' (Cl)A6' (OMe)A7' (F)A8' (GeH3)A9' (SiH3)A10' (AlH2)

B1' (H)B2' (NMe2)

B3' (Me)B4' (SMe)B5' (Cl)B6' (OMe)B7' (F)B8' (GeH3)B9' (SiH3)B10' (AlH2)

17.838.177.284.8117.8-0.8-16.1-29.32.354.522.342.481.590.2122.20.1-14.8-28.5

46.167.0105.9114.0147.426.812.5-2.232.983.951.173.3114.1121.8153.830.015.6-0.2

28.328.928.729.229.627.628.631.530.629.428.830.932.631.631.629.930.428.7

Results and Discussion

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.

Si

[Os]G

OXR

Si

[Os]

OXR

10

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.

Results and Discussion

11

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.

Summary

12

Outline

11

3

[1,3]- substituent Shift for the Formation of the Silabenzenes

2

3 Future work

The aromaticity of metallasilapentalynes

13

pentalyne metallapentalyne metallasilapentalyne

III

Antiaromatic Aromatic Aromatic

III

[M] Si[M]?

8e

116 °

10e

129.5 °distorted triple

bondextremely strained

reduce the ring strain significantly

Introduce a metal 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.

Background

14

Os

Si

PH3

PH3

Cl

A

B2.299

1.8091.381

1.429

1.382

1.4201.363

2.035

2.147

112.6

Ring A;NICS(0) = - 7.3 NICS(1) = - 9.8NICS(2) = - 5.9

NICS(-1) = - 10.0NICS(-2) = - 6.2

NICS(1)zz = - 19.8

Ring B:NICS(0) = - 8.9NICS(1) = - 8.8NICS(2) = - 4.1NICS(-1) = - 9.1NICS(-2) = - 4.2

NICS(1)zz = - 16.2

[Os] E

(E = Si)

(E = Si)

(E = Si)

[Os] E (E = Si)

[Os]=OsCl(PH3)2

(E = C)

(E = C)

(E = C)

(E = C)

[Os] E

[Os] E [Os] E

[Os] E[Os] E

[Os] E

ISE= - 22.8

ISE= - 23.3

ISE= - 21.2

ISE= - 19.6

ISE = -18.7

ISE= - 17.5

ISE= - 16.5

ISE= - 16.9

Results and Discussion

The aromaticity of metallasilapentalynes

Figure 9. The optimized structure 、 the ISEs values of the osmasilapentalynes and the NICS values of the each ring

The effect of ligand

15

[Os] Si

N

[Os] Si-18.0 ( -32.8 )+N

N

N

2.388

[Os] SiN

N[Os] Si

0.2 -12.1 )+

The effect of base

[Os]

CH3

CH3

SiH3C

112.7

[Os]

CH3

CH3

SiH3C

partially optimized optimized

74.7

74.0

1

2

3

G = -10.0 E = -8.8

The ring strain

Os

Si

CO

PH3

Cl

Os

Si

CO

CO

Cl

Os

Si

PF3

PF3

Cl

Os

Si

PMe3

PMe3

Cl

Os

Si

CO

PH3

Cl

Os

Si

CO

CO

Cl

Os

Si

PF3

PF3

Cl

Os

Si

PMe3

PMe3

Cl

Os-Si

2.3030.8730

2.3200.8387

2.3080.8895

2.2841.0153

E = -18.09

E = -18.07

E = -18.46

E = -18.89

Os

Si

PH3

PH3

ClOs

Si

PH3

PH3

Cl 2.2910.9784

E = -18.70

HOMO-LOMO

2.96 ev

2.78 ev

2.83 ev

3.10 ev

3.07 ev

[Os]

CH3

CH3

CH3C

129.5

[Os]

CH3

CH3CH3C

partially optimized optimized

74.5

72.8

E = 24.8

16

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.

Summary

17

Outline

1

3

[1,3]- substituent Shift for the Formation of the Silabenzenes

2

3 Future work

The aromaticity of metallasilapentalynes

18

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.

[Os] Si Si[M]

M = other metals

GeGeO

R1

X OXR1

SnSnO

R1

X OXR1

19

Organophosphorus

compounds

19

pesticide

flame retardant

medicine

antibacterial agents

enzyme inhibitors

anti HIV agents

？P

OEtO

EtOH

P

OEtO

EtO

20

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

Condition Optimization

21

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！