![Platform
• Mo-Mo quadruple bond
(1σ, 2π, 1δ)
• δ bond is weakly
overlapping, electrons are
mostly localized
• K4[Mo2(SO4)4]Cl (1),
K4[Mo2(SO4)4] (2),
MIT Department of Chemistry
Mo2Cl4(PMe3)4 (3)
Module 8 Laboratory Manual](https://image.slidesharecdn.com/mod8presentation-130314230821-phpapp01/85/Chakarawet1-4-320.jpg)
![K4[Mo2(SO4)4]Cl (1)
• λmax=1412 nm
(7100 cm-1); δ-δ*
transition
Absorbance
• Vibronic fine
structures with
average splitting
5800 6300 6800 7300 7800 8300 8800 9300 9800
of 327 cm-1
ṽ (cm-1)
• One-electron
Absorption spectrum of K4[Mo2(SO4)4]Cl (1) energy, W=7100
cm-1](https://image.slidesharecdn.com/mod8presentation-130314230821-phpapp01/85/Chakarawet1-5-320.jpg)
![K4[Mo2(SO4)4] (2)
Absorbance
11000 16000 21000 26000 31000
ṽ (cm-1)
Absorption spectrum of K4[Mo2(SO4)4] (2)](https://image.slidesharecdn.com/mod8presentation-130314230821-phpapp01/85/Chakarawet1-6-320.jpg)
![Conclusion
• In [Mo2(SO4)4]4-/3-, δ bond is found to have
W=7100 cm-1, K=8500 cm-1. Higher two-
electron energy than one-electron energy
• In Mo2Cl4(PMe3)4, 1δδ-1δδ* transition follows
Frank-Condon Principle](https://image.slidesharecdn.com/mod8presentation-130314230821-phpapp01/85/Chakarawet1-9-320.jpg)
Chakarawet1
- 1. Spectroscopic Studies of Two-Electron δ Bond on Dimolybdenum Quadruple Bond Platform Khetpakorn Chakarawet November 16, 2012 5.37 Organic and Inorganic Chemistry Laboratory, Module 8 Department of Chemistry, Massachusetts Institute of Technology
- 2. Background Theory • Coulson and Fischer: 2 electrons in H2 molecule • Two electron energy (K) depends on distance between the two electrons (rH1,H2) MIT Department of Chemistry Module 8 Laboratory Manual
- 3. • If the two electrons are localized, K will be large • Two-electron energy diagram MIT Department of Chemistry Module 8 Laboratory Manual
- 4. Platform • Mo-Mo quadruple bond (1σ, 2π, 1δ) • δ bond is weakly overlapping, electrons are mostly localized • K4[Mo2(SO4)4]Cl (1), K4[Mo2(SO4)4] (2), MIT Department of Chemistry Mo2Cl4(PMe3)4 (3) Module 8 Laboratory Manual
- 5. K4[Mo2(SO4)4]Cl (1) • λmax=1412 nm (7100 cm-1); δ-δ* transition Absorbance • Vibronic fine structures with average splitting 5800 6300 6800 7300 7800 8300 8800 9300 9800 of 327 cm-1 ṽ (cm-1) • One-electron Absorption spectrum of K4[Mo2(SO4)4]Cl (1) energy, W=7100 cm-1
- 6. K4[Mo2(SO4)4] (2) Absorbance 11000 16000 21000 26000 31000 ṽ (cm-1) Absorption spectrum of K4[Mo2(SO4)4] (2)
- 7. Mo2Cl4(PMe3)4 (3) Emission spectrum Absorption spectrum 11000 13000 15000 17000 19000 21000 23000 25000 27000 29000 ṽ (cm-1) Emission and absorption spectra of Mo2Cl4(PMe3)4 (3) *intensities are scaled by arbitrary factor
- 8. Mo2Cl4(PMe3)4 (3) • Absorption spectrum λmax= 580 nm (17200 cm-1); 1δδ-1δδ* transition • Emission spectrum λmax= 712 nm (14000 cm-1) 1δδ-1δδ* transition • Spectra overlap; Frank-Condon Principle
- 9. Conclusion • In [Mo2(SO4)4]4-/3-, δ bond is found to have W=7100 cm-1, K=8500 cm-1. Higher two- electron energy than one-electron energy • In Mo2Cl4(PMe3)4, 1δδ-1δδ* transition follows Frank-Condon Principle