Crystal and molecular structure of 2-chlorotropone

Abstract

X-Ray crystallographic analysis has established that the π-electron system in 2-chlorotropone (I; X = Cl) is only partially delocalised and that marked bond-length alternation occurs. The seven-membered ring is planar to within the limits of experimental accuracy. The crystals are orthorhombic, space group Pna2₁ with Z= 4 in a cell of dimensions a= 12·43, b= 12·57, c= 4·01 Å. Atomic parameters are based on least-squares refinement, yielding a final value of R of 10·7% for 760 structure amplitudes.