Second-sphere co-ordination of neutral and cationic transition metal complexes by crown ethers

Abstract

The[ammine(η⁵-cyclopentadienyl) dicarbonyl-iron(II)] cation and the neutral complex amminepentacarbonyltungsten(0), form 1:1 adducts in solution with 18-crown-6 and dibenzo-18-crown-6 by virtue of hydrogen bonding between the ammine ligand in the transition metal complex and oxygen atoms of the crown ether; a crystalline adduct, [W(CO)₅NH₃ dibenzo-18-crown-6], has been isolated as a benzene solvate.