Crystal Structures of Cobalt Sandwich Complexes in the η5-Cyclopentadienyl/η4-Cyclobutadiene and η5-Cyclopentadienyl/η4-Cyclopentadienone Families

Abstract

The crystal structures of six cobalt sandwich complexes—four in the η5-cyclopentadienyl/η4-cyclobutadiene family, two from the related η5-cyclopentadienyl/η4-cyclopentadienone family—are presented and discussed alongside related structural precedents. In each of the complexes an undecorated cyclopentadienyl ligand is present whereas the partner cyclobutadiene or cyclopentadienone ligand bears four identical aromatic substituents (phenyl, p-tolyl, p-fluorophenyl, 2-thienyl or 2,2′-bithienyl). This range of substituents allows for detailed structural comparison between members of the families of sandwich complexes presented here, and with previously reported structures. Crystal structures of members of the η5-cyclopentadienyl/η4-tetraarylcyclobutadiene (left) and η5-cyclopentadienyl/η5-cyclopentadienone (right) families of sandwich complexes are presented.