Table 1.

Values of K_trans/cis and E_n→π* for compounds 1–4

Compound	Z	Ktrans/cisa	Conformation	En→π* (kcal/mol)
1	H3C–	4.0b	—	0.40
2	H2FC–	2.7	anti-periplanar	0.76
			syn-periplanar	0.29
			anti-periplanar	0.30
3	HF2C–	3.4	anti-clinical	0.38
			syn-periplanar	0.38
4	F3C–	4.6	—	0.37

^aMeasured in CDCl₃ at 25 °C.

^bfrom Ref 6a.