Stereochemistry of some organic derivatives of Group VB elements. Part XI. Crystal and molecular structure of triphenylarsonium 3,4-dibenzoylcyclopentadienylide

Abstract

The crystal and molecular structure of the title compound has been determined by three-dimensional X-ray analysis. Crystals are monoclinic, space group C2/c, with a= 25.584(2), b= 13.863(2), c= 18.055(2)Å, β= 113.17(1)°, Z= 8. The structure was solved by the heavy-atom method and refined by block-diagonal least-squares calculations to R 0.049 for 2 484 observed reflexions measured by diffractometer.

The crystal structure consists of discrete molecules separated by van der Waals distances; one of the benzoyl groups is disordered over two sites with occupancy factors ⅔ : ⅓. Bond lengths lie in the expected ranges [C–C(cyclopentadienyl) 1.383(8)–1.439(9), As–C(Ph) 1.910–1.917(7), As–C(cyclopentadiene) 1.868(5)Å] and those associated with the cyclopentadienyl ring are used to assess the contributions of canonical forms to the ground-state structure.