View source for Rep:JHT114 Y3C TransitionStates fw

= JHT Y3C Transition States Further Work =
==Introduction==

Both the 4π electrocyclic and 6π electrocyclic ring-closing reactions were investigated at the PM6 level. The reaction coordinates of these reactions were visualised, and an MO analysis was done on the 4π electrocyclic system.

[[File:Jht fw scheme.jpg|frame|center]]

== 4π Electrocyclic ==

===Optimisation of Structures (PM6 Level) ===

{|class="wikitable" 
!colspan="4" style="text-align: center;background: #0D4F8B; color: white;"| Table 1: Optimised Structures at PM6 Level
|-
| style="text-align: center;"|Reactant
| style="text-align: center;"|Transition State
| style="text-align: center;"|Product
|-
| <jmol>
<jmolApplet>
  <color>black</color>
  <size>250</size>
  <script>frame 72 </script>
  <uploadedFileContents>Jht 4pi rxt fw.LOG</uploadedFileContents>
  </jmolApplet>
</jmol>
| <jmol><jmolApplet>
  <color>black</color>
  <size>250</size>
  <script>frame 86 </script>
  <uploadedFileContents>Jht 4PI TS fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
| <jmol><jmolApplet>
  <color>black</color>
  <size>250</size>
  <script>frame 40 </script>
  <uploadedFileContents>JHT 4PI PDT FW.LOG</uploadedFileContents>
</jmolApplet></jmol>
|-
|}

===Visualisation of Reaction Coordinate===

{| class="wikitable"
! style="background: #0D4F8B; color: white;" | Reaction Coordinate
| [[File:Jht 4pi movie2 fw.gif]]
|-
! style="background: #0D4F8B; color: white;" | IRC Calculation
| [[File:Jht 4pi IRC E fw.PNG|350px]]
|-
! style="background: #0D4F8B; color: white;" | IRC File
| [[File:Jht 4PI IRC fw.LOG]]
|-
|}

(A bit difficult to see the reaction from this angle [[User:Tam10|Tam10]] ([[User talk:Tam10|talk]]) 16:03, 19 February 2018 (UTC))

===Molecular Orbitals and Analysis===

{| class="wikitable"
! style="background: #0D4F8B; color: white;" | 1,3-Butadiene Fragment
! style="background: #0D4F8B; color: white;" | Molecular Orbital Diagram
! style="background: #0D4F8B; color: white;" | Cyclobutene TS
|-
| <jmol><jmolApplet>
  <color>white</color>
  <size>200</size>
  <script>frame 72; mo 34; mo nodots nomesh fill translucent; mo cutoff 0.02; mo titleformat ""; set antialiasdisplay on</script>
  <uploadedFileContents>Jht 4pi rxt fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
| rowspan="6"|[[File:JHT 4PI mo10 FW.jpg]]
| <jmol><jmolApplet>
  <color>white</color>
  <size>200</size>
  <script>frame 86; mo 34; mo nodots nomesh fill translucent; mo cutoff 0.02; mo titleformat ""; set antialiasdisplay on</script>
  <uploadedFileContents>Jht 4PI TS fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
|-
! style="color: blue;"| LUMO, MO34, S
! style="color: blue;"| LUMO, MO34, A
|-
| <jmol><jmolApplet>
  <color>white</color>
  <size>200</size>
  <script>frame 72; mo 33; mo nodots nomesh fill translucent; mo cutoff 0.02; mo titleformat ""; set antialiasdisplay on</script>
  <uploadedFileContents>Jht 4pi rxt fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
| <jmol><jmolApplet>
  <color>white</color>
  <size>200</size>
  <script>frame 86; mo 33; mo nodots nomesh fill translucent; mo cutoff 0.02; mo titleformat ""; set antialiasdisplay on</script>
  <uploadedFileContents>Jht 4PI TS fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
|-
! style="color: blue;"| HOMO, MO33, A
! style="color: blue;"| HOMO, MO33, A
|-
| <jmol><jmolApplet>
  <color>white</color>
  <size>200</size>
  <script>frame 72; mo 32; mo nodots nomesh fill translucent; mo cutoff 0.02; mo titleformat ""; set antialiasdisplay on</script>
  <uploadedFileContents>Jht 4pi rxt fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
| <jmol><jmolApplet>
  <color>white</color>
  <size>200</size>
  <script>frame 86; mo 32; mo nodots nomesh fill translucent; mo cutoff 0.02; mo titleformat ""; set antialiasdisplay on</script>
  <uploadedFileContents>Jht 4PI TS fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
|-
! style="color: blue;"| HOMO(-1), MO32, A
! style="color: blue;"| HOMO(-1), MO32, S
|-
|}


For a typical 4 π system, the HOMO should resemble that of '''{{fontcolor1|blue|HOMO(-1), MO32, A}}''' of the diene fragment, which could be predicted using Huckel theory. However, the '''{{fontcolor1|blue|HOMO, MO32, A}}''' does not resemble this. Thus, it could be possible that MO32 is formed as a result of mixing of with the ester groups, which are in conjugation with the double bond.

Nonetheless, from '''{{fontcolor1|blue|MO32}}''' and '''{{fontcolor1|blue|MO34}}''', it can be noted that the reaction is {{fontcolor1|red
|conrotatory}}. This is in accordance to a thermal reaction governed by the Woodward-Hoffmann rules:

(The orbitals aren't too easy to understand in this example. There also might be some swapping going on in the orbitals [[User:Tam10|Tam10]] ([[User talk:Tam10|talk]]) 16:03, 19 February 2018 (UTC))

  4r<sub>a</sub>     = 1
  (4n+2)<sub>s</sub> = 0
  sum     = 1 (odd number)

== 6π Electrocyclic ==
===Optimisation of Structures (PM6 Level) ===

{|class="wikitable" 
!colspan="4" style="text-align: center;background: #0D4F8B; color: white;"| Table 2: Optimised Structures of 6п electrocyclic reaction at PM6 Level
|-
| style="text-align: center;"|Reactant
| style="text-align: center;"|Transition State
| style="text-align: center;"|Product
|-
| <jmol>
<jmolApplet>
  <color>black</color>
  <size>250</size>
  <script>frame 48 </script>
  <uploadedFileContents>JHT 6PI RXT4 FW.LOG</uploadedFileContents>
  </jmolApplet>
</jmol>
| <jmol><jmolApplet>
  <color>black</color>
  <size>250</size>
  <script>frame 106 </script>
  <uploadedFileContents>JHT 6PI TS.LOG</uploadedFileContents>
</jmolApplet></jmol>
| <jmol><jmolApplet>
  <color>black</color>
  <size>250</size>
  <script>frame 66 </script>
  <uploadedFileContents>JHT 6PI PDT fw.LOG</uploadedFileContents>
</jmolApplet></jmol>
|-
|}

===Visualisation of Reaction Coordinate===

{| class="wikitable"
! style="background: #0D4F8B; color: white;" | Reaction Coordinate
| [[File:Jht 6pi movie fw.gif]]
|-
! style="background: #0D4F8B; color: white;" | IRC Calculation
| [[File:Jht 6pi IRC E fw.PNG|350px]]
|-
! style="background: #0D4F8B; color: white;" | IRC File
| [[File:JHT 6PI IRC fw.LOG]]
|-
|}

In contrast to the 4π system, the 6π system shows a {{fontcolor1|red|disrotatory}} behaviour, as can be seen from the gif file in the reaction coordinate above. This is in accordance to the Woodward-Hoffman rules under thermal conditions:

  4r<sub>a</sub>     = 0
  (4n+2)<sub>s</sub> = 1
  sum     = 1 (odd number)

(Good. This can also be reinforced with orbital analysis [[User:Tam10|Tam10]] ([[User talk:Tam10|talk]]) 16:03, 19 February 2018 (UTC))

==Conclusion==

Both calculations are in accordance to the Woodward-Hoffman analysis, where a 4π electrocyclic reaction would proceed in a conrotatory manner, which allows for antarafacial interactions; whereas a 6π electrocyclic reaction would proceed in a disrotatory manner, allowing suprafacial interactions.

== Exercises 1, 2 and 3==
Links to previous exercises:

Exercise 1: https://wiki.ch.ic.ac.uk/wiki/index.php?title=JHT114_Y3C_TransitionStates

Exercise 2: https://wiki.ch.ic.ac.uk/wiki/index.php?title=JHT114_Y3C_TransitionStates_ex2

Exercise 3: https://wiki.ch.ic.ac.uk/wiki/index.php?title=JHT114_Y3C_TransitionStates_ex3