Theoretical energy-based conformational analysis of divinyl selenide performed at the MP2/6-311G** level is substantiated by the second-order polarization propagator approach (SOPPA) calculations and experimental measurements of its (77)Se-(1)H spin-spin coupling constants, demonstrating marked stereochemical behavior in respect of the internal rotation of both vinyl groups around the Se-C bonds. Based on these data, divinyl selenide is shown to exist in an equilibrium mixture of three nonplanar conformers: one the preferred syn-s-cis-s-trans and two minor anti-s-trans-s-trans and syn-s-trans-s-trans forms.

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