The Stability and Aromaticity of Metallasilapentalynes ： A DFT Study

Speaker: Xuerui WangAdvisor : Jun Zhu

Wang, X.; Zhu, C.; Xia, H.; Zhu, J. Organometallics 10.1021/om500170w.

Outline

11

3

Background

2

2 Results and Discussion

3 Summary

3

Background In 1979 ,Thorn and Hoffmann predicted the three classes of stable metallabenzenes

Thorn, D. L.; Hoffman, R. Nouv. J. Chim, 1979, 3, 39

In 1982, the first metallabenzene

Os(CO)(CS)(PPh3)3 + 2HCCH

Os

PPh3

PPh3

S

CO

In 2001, the first metallabenzyne

W. R. Roper, J. M. Waters, J. Chem. Soc. Chem.Commun, 1982, 811T. Wen, G. Jia, Angew. Chem. Int. Ed, 2001, 40, 1951

4

Background

Os

H

PPh3

Cl

Ph3PCl

Os

PPh3

PPh3

PPh3

Cl

ClBF4

Only a few examples of aromatic metallabicycles complex

Zhu, C.; Li, S.; Luo, M.; Zhou, X.; Niu, Y.; Lin, M.; Zhu, J.; Cao, Z.; Lu, X.; Wen, T. B; Xie, Z.; Schleyer, P. v. R.; Xia, H. Nat. Chem. 2013, 5, 698.

Zhu, C.; Luo, M.; Zhu, Q.; Zhu, J.; Schleyer, P. v. R.; Wu, J.; Lu, X.; Xia, H. Nat. Commun. 2014, 5, 3265.

[M] = transition metal fragment

[M] [M] Si

Antiaromatic Aromatic Aromatic

Pentalyne Metallapentalyne Metallasilapentalyne

I II III

?

silicon atom is reluctant to participate in bonding

Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984 , 23 , 272.

Wang, X.; Zhu, C.; Xia, H.; Zhu, J. Organometallics 10.1021/om500170w.

2. Computational Method2. Computational Method

Package : Gaussian 03

Method: DFT(B3LYP)

Basis sets : C, H, O, N : 6-311++G **

LanL2DZ: P(ζ(d) = 0.340), Cl(ζ(d) = 0.514), Si (ζ(d) = 0.262)

Fe(ζ(f) = 2.462, Ru(ζ(f) = 1.235), Os(ζ(f) = 0.886)

1. Ehlers, A. W.; Böhme, M.; Dapprich, S.; Gobbi, A.; Höllwarth, A.; Jonas, V.; Köhler, K. F.; Stegmann, R.; Veldkamp, A.; G., F. Chemical Physics

Letters 1993, 208, 111.

2. Check, C. E.; Faust, T. O.; Bailey, J. M.; Wright, B. J. J. Phys. Chem. A. 2001, 105, 8111.

6

Results and Discussion

Geometry and Stability of Metallasilapentalyne.

[Fe] Si

10.536.6 29.20.0 19.6 20.5 34.9

0.0 51.3 25.8 30.1 35.3 46.3 15.9

0.0 50.5 29.2 30.9 37.6 46.3 16.9

[Fe]

SiH

[Fe]

SiH

Si

[Fe]

SiH

[Fe]

HSi

[Fe] [Fe]HSi

[Ru] Si [Ru]

SiH

[Ru]

SiH

Si

[Ru]

SiH

[Ru]

HSi

[Ru] [Ru]HSi

[Os] Si [Os]

SiH

[Os]

SiH

Si

[Os]

SiH

[Os]

HSi

[Os] [Os]HSi

[M] = MCl(PH3)2

Figure 1. Relative stability of the isomers of metallasilapentalynes with the silicon atom at different positions.

most stable second most stablediffuse d-orbitals

7

Results and Discussion

[Os] E

[Os] = OsCl(PH3)2

1a (E = C)1b (E = Si)1

23

4

5

6

2.299

1.809

1.3811.4291.3821.420

1.363

2.035

2.147

112.6

1b

Figure 2. The optimized structure with selected bond lengths (Å) and bond angles () in osmasilapentalyne 1b.

♦ 2.325 Å in the first osmium silylene ♦ 2.176 Å in the first osmium silylyne

8

Results and Discussion

Table 1. The bond lengths (Å), Wiberg bond indices and charges of Os≡E triple bonds (E = C or Si) in 1a and 1b.

1b 1b''1b'

[Os] Si[Os] Si [Os] SiA

Figure 3. A. The resonance structures of osmasilapentalyne 1b. B. Electron localization function (ELF) calculations with isovalue of 0.85 on osmasilapentalyne 1b and osmapentalyne 1a.

Bond length (Å)

Wiberg bond order

Charge(Os) Charge(E)

C 1.845 1.70 -0.97 +0.17

Si 2.299 1.25 -1.42 +0.14

highly polarized

OsSi triple bond

1a 1b

B

OsSi bond : 27% Os 73% Si

Si :components of s and p orbitals are 56% and 44%

9

Results and Discussion

[Os]

CH3

CH3

SiH3C

112.6°

[Os]

CH3

CH3

SiH3C

partially optimized optimized

74.7°

74.0°

1

3

6

E = - 8.7

[Os] = OsCl(PH3)2

[Os]

CH3

CH3

H3C

129.5°

[Os]

CH3

CH3H3C

partially optimized optimized

74.5°

72.8°

E = - 24.8

[Os] = OsCl(PH3)2

141.8°

167.0°

112.6° 141.8°

129.5° 167.0°

29.0

37.5

Figure 4. The calculated strain energy of osmasilapentalyne 1b based on acyclic reference compounds. The correction of the zero-point energy is included in kcal mol -1.

Ring Strain

10

Results and Discussion

The Aromaticity of Metallasilapentalynes[Os] Si

[Fe]=FeCl(PH3)2

ISE = -15.0

[Ru]=RuCl(PH3)2

ISE= - 17.3

[Os]=OsCl(PH3)2

ISE = -18.3

ISE= - 17.5

ISE= - 16.5

ISE= - 16.9

[Os] Si

[Os] Si[Os] Si

[Os] Si[Os] Si

[Os] Si[Os] Si

[Ru] Si[Ru] Si

[Fe] Si[Fe] Si

[M] SiA B

[M] = MCl(PH3)2

Os Ru FeNICS(1)zz

-19.8-16.2

-14.2-10.2

-15.3-13.4

Ring ARing B

Figure 7. The NICS(1)zz values (ppm) for rings A

and B in metallasilapentalynes.

Figure 8. “isomerization stabilization energy” (ISE) of

metallasilapentalyne.

11

Results and Discussion

The Aromaticity of Osmasilapentalynes

HOMO (-5.67 ev) HOMO-1(-5.90 ev) HOMO-2 (-6.14 ev)

HOMO-3 (-6.96ev) HOMO-8 (-8.63 ev) HOMO-12(-9.96 ev)

x

y

z

SiPH3

PH3

Os

NICS(1)zz

Total

HOMO HOMO-2 HOMO-12

All orbitals

Orbitals

HOMO-1

Cl

+2.1 / -7.6 +6.2 / +10.1 +4.7 / +5.0

-5.3 / +1.2 -6.9 / -8.4 -7.0 / -2.2

HOMO-3 HOMO-8

-0.2 / -4.8

-12.2 / -7.2

+6.2 / +10.1

-19.8 / -16.2

-13.6 / -14.3

1b

A

B

three Hückel-type MOs HOMO, HOMO-2, and HOMO-12

two Möbius-type MOs HOMO-3 and HOMO-8

mixed aromaticity with Möbius aromaticity dominated

12

Effect of the Phosphonium Substituent on the Aromaticity in Osmasilapentalynes:

[Os] Si[Os] SiISE= - 25.1

ISE= - 31.0

PMe3PMe3

[Os]

PMe3

[Os]

PMe3

[Os] = OsCl(PH3)2

ISE= - 17.5

[Os] Si[Os] Si

ISE= - 23.3

[Os][Os]

SiCO

CO

Os Cl

Bond lengthBond order

2.3291.09

2.2921.30

2.2991.25

SiPMe3

PMe3

Os Cl

SiPH3

PH3

Os Cl

-19.8/-16.2 -16.3/-14.2 -21.9/-17.8NICS(1)ZZ A/B

A

B

OsSi

Ligand Effects on the Structure for Osmasilapentalynes

Effect of Lewis Base on the Stabilization for Osmasilapentalyne:

[Os] = OsCl(PH3)2

= -32.8+

= -12.1

[Os] Si

N N

[Os] Si

N

N

+

[Os] SiN

[Os] SiN

1b

1b

13

Summary

1.The computed negative ISE and NICS(1)zz values reveal

aromatic character of osmasilapentalyne.

2. Aromaticity in osmasilapentalyne is reduced in comparison with osmapentalyne.

3.The phosphonium substituent, -donor ligands and Lewis base can enhance the aromaticity or stability of osmasilapentalynes.

4.All these findings could be helpful for the synsthesis of the first metallasilapentalyne.

14

Future work

[M] = transition metal fragment

[M] [M] Si

Aromatic Aromatic

Metallapentalyne Metallasilapentalyne

I III

?

[M]

Aromatic

Metallapentalene

II

[M] Si

Aromatic

Metallasilapentalyne

IV

Geometry and stability of metallasilapentaleneThe aromaticity of metallasilapentalynesEffect of the substituent on the aromaticity in osmasilapentalenesLigand effects on the structure for osmasilapentalenes

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