eaxys Prize lub Symposium in Japan, March 28, 2014 Profile JSPS Stephan

13 

Loading.... (view fulltext now)

Loading....

Loading....

Loading....

Loading....

全文

(1)

16:00-

ケイ素

反応による

-ケイ素三重結合化合物ジシリンとアゾベンゼンとの

Si

2

N

2

四員環ビラジカロイドの合成

Access to a Stable Si

2

N

2

4-Membered Ring with

Non-Kekulé Singlet Biradical Character from a Disilyne

竹内 勝彦 先生 Dr.

Katsuhiko

Takeuchi

講演者プロフィール

竹内

勝彦(たけうち かつひこ)

京都大学 化学研究所 助教

2007年3月 筑波大学 第一学群 自然学類 化学専攻 卒業

2009年3月 筑波大学大学院 数理物質科学研究科 化学専攻 博士前期課程 修了

2012年3月 筑波大学大学院 数理物質科学研究科 化学専攻 博士後期課程 修了

2012年4月∼2012年4月 トロント大学 博士研究員 (JSPS海外特別研究員)

2013年8月∼現在 京都大学 化学研究所 遷移金属錯体化学研究領域 小澤研究室 助教

(2)

竹内 勝彦

京都大学 化学研究所 遷移金属錯体化学研究領域 小澤研究室

Si

N

Si

N

ケイ素―ケイ素三重結合化合物ジシリンとアゾベンゼン

との反応によるSi

2

N

2

四員環ビラジカロイドの合成

Access to a Stable Si

2

N

2

4-Membered Ring with

Non-Kekulé Singlet Biradical Character from a Disilyne

Reaxys Prize Club Symposium in Japan, March 28, 2014

01

Profile

京都大学 化学研究所 助教(小澤研究室)

筑波大学大学院 数理物質科学研究科 化学専攻 博士後期課程 修了(関口研究室)

カナダ トロント大学 JSPS海外特別研究員(Stephan研究室)

2012年 3月

2012年 4月 ∼ 2013年 7月

2013年 8月 ∼

2007年 3月

2009年 3月

筑波大学大学院 数理物質科学研究科 化学専攻 博士前期課程 修了(関口研究室)

筑波大学 第一学群 自然学類 化学専攻 卒業(関口研究室)

(3)

02

Research

1.ケイ素–ケイ素三重結合化合物の反応性

2.シリルホスフィンのフラストレイティドルイスペアとしての反応性

3.ホスファアルケンを有する多座配位子の研究

disilyne

+

Bulky

Lewis Base

Bulky

Lewis Acid

N

P

P

Mes*

Mes*

N

P

P

Mes*

t

Bu

t

Bu

Frustrated 

Lewis Pair

03

Research

ケイ素―ケイ素三重結合化合物ジシリンとアゾベンゼン

との反応によるSi

2

N

2

四員環ビラジカロイドの合成

Si

2

N

2

4-membered ring biradicaloid

Ar = 3,5-Me

2

C

6

H

3

Si

N

Si

(4)

04

Introduction: Disilyne

the first isolable disilyne 1

Sekiguchi (2004)

Si

Si

Si

Si

Me

3

Si

Me

3

Si

Me

3

Si

SiMe

3

Me

3

Si

SiMe

3

SiMe

3

SiMe

3

Si

Si

Si

Si

Me

3

Si

Me

3

Si

Me

3

Si

SiMe

3

Me

3

Si

SiMe

3

SiMe

3

SiMe

3

Br

Br

Br

Br

4 KC

8

THF

Si

Si

the first isolable Si=Si double bonded compound

disilene

West (1981)

Robert C. West

University of Wisconsin–Madison

05

Introduction: Disilyne

Sekiguchi (2004)

Tokitoh (2008)

the first aryl substituted disilyne

Si

Si

SiMe

3

Me

3

Si

SiMe

3

SiMe

3

SiMe

3

Me

3

Si

Me

3

Si

SiMe

3

SiMe

3

Me

3

Si

Me

3

Si

Me

3

Si

SiMe

3

Me

3

Si

Iwamoto, Ishida (2013)

the first alkyl substituted disilyne

Si

Si

Si

Si

Me

3

Si

Me

3

Si

Me

3

Si

SiMe

3

Me

3

Si

SiMe

3

SiMe

3

SiMe

3

Si

Si

C

C

SiMe

3

Me

3

Si

Me

3

Si

SiMe

3 t

Bu

t

Bu

Isolable Disilynes

Si

Si

Si

Si

Me

3

Si

Me

3

Si

Me

3

Si

SiMe

3

Me

3

Si

SiMe

3

SiMe

3

SiMe

3 t

Bu

Sekiguchi (2010)

(5)

2.0622(9) Å

137.44(4)º

2.3698(6) Å

06

Introduction: Disilyne

Si=Si 2.14 ~ 2.29 Å

Si–Si 2.34 ~ 2.37 Å

cf. Typical Bond Lengths

Si1

Si2

Si2´

Si1´

07

Introduction: Disilyne

R

R

R

R

R

R

C

Si

Ge

Sn

Pb

80

60

160

140

120

100

r

max

(pm)

Orbital radius of group 14 elements

p-orbital



s-orbital



C

C

R

R

Si

Si

R

R

(6)

HF/6-31G(d)

HOMO

HOMO–1

LUMO+1

LUMO

–7.10

–6.69

1.03

1.88

E (eV)

–10.89

5.92

C

C

H

H

0

08

Introduction: Disilyne

1) R. Kinjo, M. Ichinohe, A. Sekiguchi, N. Takagi, M. Sumimoto, and S. Nagase, J. Am. Chem. Soc., 129, 7766 (2007). 2) K. Takeuchi, M. Ikoshi, M. Ichinohe, and A. Sekiguchi, J. Am. Chem. Soc., 132, 930 (2010).

3) K. Takeuchi, M. Ikoshi, M. Ichinohe, and A. Sekiguchi, J. Organomet. Chem., 696, 1156 (2011). 4) K. Takeuchi, M. Ichinohe, and A. Sekiguchi, Organometallics, 30, 2044 (2011).

5) K. Takeuchi, M. Ichinohe, and A. Sekiguchi, J. Am. Chem. Soc., 130, 16848 (2008). 6) K. Takeuchi, M. Ichinohe, and A. Sekiguchi, J. Am. Chem. Soc., 134, 2954 (2012).

disilyne 1

1)

1)

PhC



CH



R

2

NH



or

Dsi = CH(SiMe

3

)

2

2,4)

R

2

BH

2,3)

stereo specific

5)

Me

3

SiCN

6)

09

Introduction: Disilyne

Si

Si

Dsi

2i

PrSi

Si

i

PrDsi

2

C

C

N

N

Me

3

Si

SiMe

3

Si

Si

Dsi

2i

PrSi

NC

Si

i

PrDsi

2

CN

t

BuNC

(7)

10

Introduction: Biradicaloid

Mes* = 1,3,5-

t

Bu

3

C

6

H

2

Niecke (1995)

Power (2004)

Lappert (2004)

Ar* = C

6

H

3

-2,6-(C

6

H

3

-2,6-

i

Pr

2

)

2

Cyclicbiradicaloids

Biradicals

pair of doublet monoradicals

triplet biradical

singlet biradical

biradicaloid

Bertrand (2002)

11

Reaction with Azobenzenes

Si

2

N

2

4-membered ring biradicaloid 2

purple crystals

(y. = 58%)

Ar = 3,5-Me

2

C

6

H

3

THF

r.t. / in dark

1 day

disilyne 1

cf. Power s Work

hexane

Ar* = C

6

H

3

-2,6-(C

6

H

3

-2,6-

i

Pr

2

)

2

E

= Ge, Sn

 1)

THF

r.t. / in dark

<5 min

(8)

12

Possible Reaction Mechanism

Si=Si

cleavage



N

N

cleavage



π* LUMO



cf. Reaction with 2-Butene

1)

1) R. Kinjo, M. Ichinohe, A. Sekiguchi, N. Takagi, M. Sumimoto, and S. Nagase, J. Am. Chem. Soc., 129, 7766 (2007).

disilyne 1

hexane

or

1 day

30 min

N

N

Si

Si

Dsi

2i

PrSi

Si

i

PrDsi

2

Ar

Ar

Si

N

N

Si

Dsi

2i

PrSi

Si

i

PrDsi

2

Ar

Ar

12

Possible Reaction Mechanism

Si=Si

cleavage



N

N

cleavage



π* LUMO



2'

0.0 kcal/mol

+43.6 kcal/mol

+29.9 kcal/mol

butadiene-2'

cyclobutene-2'

bis(silylene)-2'

not found

Si

N

N

Si

Dsi

2i

PrSi

Si

i

PrDsi

2

Ar

Ar

N

N

Si

Si

Dsi

2i

PrSi

Si

i

PrDsi

2

Ar

Ar

B3LYP/6-31G(d)

(9)

Si1

N1

Si2

Si1

'

N1

'

C1

'

C1



Si2

'

13

Molecular Structure of Biradicaloid

2

Figure 1. ORTEP drawing and selected structural parameters of 2.

Monoclinic C2/c 

Z = 4

R

1

= 0.0394 [I>2σ(I)]

wR

2

= 0.1193 [All Data]

GOF = 1.032

Σ(Si1)

=

318º

Σ

(N1) = 360º

sum of the internal angles of the ring = 360º

a purple crystal

from THF

in Å

1.758(3)

1.756(3)

2.618(2)

2.4658(15)

1) C. Cui, M. M. Olmsted, and P. P. Power, J. Am. Chem. Soc., 126, 6510 (2004).

2) H. Cox, P. B. Hitchcock, M. F. Lappert, and L. J.-M. Pierssens, Angew. Chem., Int. Ed., 43, 4500 (2004). 3) N. Wiberg, H. Schuster, A. Simon, and K. Peters, Angew. Chem., Int. Ed., 25, 79 (1986).

cf. Related Compounds

Σ(Ge) = 322º

Σ(Sn) = 256º

Si–Si = 2.697 Å

1) 2)

3)

14

AIM Analysis of Biradicaloid

2

2'

2

(Ar = 3,5-Me

2

C

6

H

3

)

(318º)

(360º)

(1.757 Å)

(2.618 Å)

Σ(Si

ring

)

Σ(N

ring

)

Si–N

Si

···

Si

Figure 1. Optimized structure and bond paths of the model compound 2'.

calc

(exp)

304º

360º

1.785 Å

2.651 Å

Si

Si

N

N

(10)

15

NMR Studies of Biradicaloid

2

2

(Ar = 3,5-Me

2

C

6

H

3

)

0

–25

–50

δ 10.4

δ

19.4

skeletal

Si

Dsi

2i

PrSi

δ 1.0, –0.3

(Me

3

Si)

2

CH

[ppm]

Figure 2.

29

Si NMR spectrum of 2 in THF-d

8

.

50

4

2

0

[ppm]

Figure 1.

1

H NMR spectrum of 2 in THF-d

8

.

6

8

Me

(Me

3

Si)

2

CH

i

Pr



25

Ar

(Me

3

Si)

2

CH

2' (singlet)

planar-2' (TS)

cf. Theoretical Studies

0.0 kcal/mol

δ(skeletal Si)

14.7

+36.8 kcal/mol

δ(skeletal Si) 52.3

GIAO/B3LYP6-311G(3d)//B3LYP6-31G(d)

+12.8 kcal/mol

2' (triplet)

16

UV-Vis Spectrum of Biradicaloid

2

Figure 1. UV-Vis spectrum of 2 in hexane superimposed by the calculated band position of 2' (left) and MOs of 2' (right) .

transition a: 515 nm (

f

= 0.0115)

transition b: 514 nm (

f

= 0.0123)

transition c: 367 nm (f = 0.0016)

HOMO–1

LUMO

HOMO

LUMO

HOMO → LUMO+1

–4.60

–2.39

HOMO

[eV]

LUMO

HOMO–1

HOMO–12

–5.33

–8.98

–0.38

LUMO+1

(σ* orbital of Si2N2 ring)

B3LYP/6-31G(d)

[

f ]

[ε]

200

800

20000

60000

[nm]

40000

600

400

529 nm 

[

ε = 3

2000]

a

b

c

356 nm

[ε = 4300]

0.01

0.02

TDDFT Calculation

2'

6

π

aromaticity?

0

0.00

(11)

17

Aromaticity of Biradicaloid

2

Σ(Si1)

=

318º

Σ

(N1) = 360º

sum of the internal angles of the ring = 360º

in Å

1.758(3)

1.756(3)

2.618(2)

Σ(Si1)

except Cl1

=

325º

Σ

(N1) = 360º

sum of the internal angles of the ring = 360º

1.7479(14)

1.7536(13)

2.5889(8)

Figure 1. Selected structural parameters of biradicaloid 2 (left) and Cl

2

-adduct 4 (right).

2'

NICS(1) = –4.2

cf. NICS Values of Model Compounds

B3LYP/6-31G(d)

4'

NICS(1) = –2.1

18

Reactivity of Biradicaloid

2

+

MeOH

(excess)



cis-3

(y. = 65%)

trans-3

2

Ar = 3,5-Me

2

C

6

H

3

THF

r.t. / 1 h

cf.

intra- or inter-molecular 

H

+

transfer



cis- or trans-3

Figure 1. ORTEP drawing of cis-3.

Si1 N1 Si2 N2 O1

closed-shell reactivity

(12)

19

Reactivity of Biradicaloid

2

+

CCl

4

(excess) 

MeOH

(excess)



cis-3

(y. = 65%)

trans-3

4

(y. = 55%)

closed-shell reactivity

radical-type reactivity

2

Ar = 3,5-Me

2

C

6

H

3

THF

r.t. / 1 h

THF

r.t. / 20 min

Figure 1. ORTEP drawing of 4.

CCl

4

MeOH



No Reaction

cf. Reactivity of Silyl Radical

Si1N1 Si1' N1' Cl1' Cl1

20

Summary

disilyne 1

2

• Although

2

has 6π-electrons in the 4-membered ring, the NICS value indicates small aromaticity.

• Reactions of

2

with MeOH and CCl

4

show that

2

has both closed-shell and radical-type reactivity.

• NMR data of

2

suggest that

2

has a singlet ground state.

• Theoretical calculations show no bonding interaction between the skeletal Si atoms of

2

.

Ar = 3,5-Me

2

C

6

H

3

(13)

21

Acknowledgment

University of Toronto

Prof. Dr. Doug W. Stephan

and

all members of Sekiguchi,

Stephan, and Ozawa groups!

University of Tsukuba

Prof. Dr. Akira Sekiguchi

A/Prof. Dr. Masaaki Ichinohe

Dr. Vladimir Ya. Lee

Dr. Masaaki Nakamoto

Kyoto University

Prof. Dr. Fumiyuki Ozawa

Dr. Masayuki Wakioka

Updating...

参照

Updating...

関連した話題 :