Abstract: | Photoelectron spectroscopy has been used to examine the consequences of steric inhibition of conjugation in a distorted vinyl sulfide and vinyl ether. Based upon the degree of interaction a deviation from coplanarity of 70°–75° is calculated for 9-oxabicyclo3.3.1]non-1-ene ( 3 ) and approximately 75°–80° for the sulfur analog 6 . |