Intramolecular Arene Bonds of Complexes Featuring Terphenyl Bis(carbene) Macrocyclic Ligands

Abstract

A series of macrocyclic bis(carbene) ligands were synthesized by linking 2,2″-bis(imidazole)terphenyl with a methylene, ethylene, propylene, or borate unit. Coordination complexes of iron were synthesized with the macrocyclic (bis)carbene ligands linked by alkyls from the reactions with Fe{N(SiMe 3 ) 2 } 2 and 5% w/w Na/NaCl. The resulting Fe(0) compounds have unusually short Fe−C bonds with the central arene of the terphenyl. The borate linked ligand was used to synthesize the isoelectronic Co(I) compound which shows similar structural characteristics to the iron compounds. We have characterized these compounds by spectroscopic methods, X-ray singlecrystal diffraction analysis, and cyclic voltammetry.