Analyze and rationalize the relative energies of the three conformers of you bia

Question

Analyze and rationalize the relative energies of the three conformers of you biaryl compound in the following manner:

1. List which conformation(s) minimize steric repulsion and explain your answer.

2. List and explain which conformation(s) maximize inter-ring pi-conjugation and explain your answer.

3. Rationalize and explain the dihedral angle of you energy minimized biaryl compound

4. Rationalize and explain the fact that 0 and 90 degree conformations are transition states

***Please make sure to explain how you came to that conclusion. That is what I'm having most difficulty with.***

This is my compound:

Optimized Biaryl Compound RB3LYP Energy-730.477029189 Hartree -458380.9101 kcal/mol Relative Energy- 0 kcal/mol Dihedral Angle: 35.802 0 degree conformation RB3LYP Energy--730.472200278 Hartree =-458377.8799 kcal/mol Relative Energy- 3.0302 kcal/mol 90-degree conformation RB3LYP Energy--730.470001231 Hartree -458376.5 kcal/mol Relative Energy- 4.4101 kcal/mol

Explanation / Answer

1. 90 degree confirmation- the H atoms of the 2 rings which are closest to the bond that connect 2 phenyl rings is minimum when angle is 90°.

2. To have pi ring conjugation the ring should be planar n continous. When there is an angle between 2 rings it doesn't form a planar system. Therefore zero degree confirmation maximises pi bonding.

3. Dihedral angle 90 means 2 rings are perpendicular to each other therefore repulsions are minimum.

4. The structures here exist in equilibrium with each other. The most stable has a higher contribution and vice versa. Therefore 0 degree and 90 degree are 2 transition states.

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