Structure of Cyclopentadiene

Abstract

The microwave spectra of the three monosubstituted ¹³C species of cyclopentadiene have been investigated. The effective rotational constants of these species together with those of the main isotopic species give the structural parameters for the ring. Labeling the methylene carbon as C₁ and numbering the other carbons sequentially we obtain: r(C₁C₂)=1.509 Å, r(C₂C₃)=1.342 Å, r(C₃C₄)=1.469 Å, ∠C₁C₂C₃=109.3°, ∠C₂C₃C₄=109.4°, ∠C₂C₁C₅=102.8°.