Stability of Gauche and Anti form in conformational Isomerism I came through this question: Which form is stable Gauche or Anti in F-CH2-CH2-F?
My answer: Due to lone pair repulsion Anti form should be more stable but the answer is given Gauche form. Please tell me how is gauche form more stable in this case?
This problem should be referred to concept called stereoelectronic effect. It is stabilized by the donation of $\sigma_{C-H}$ bond to $\sigma_{C-F}$ bond, leading to decrease energy of the whole system.