Pyracenebis(imidazolylidene): a new Janus-type biscarbene and its coordination to rhodium and iridium

摘要

A pyracene-linked bis-azolium compound has been obtained from the bisannulation of tetrakis(iminopyracene) (TIP) with chloromethyl methyl ether. The resulting bisazolium salt was readily coordinated to rhodium and iridium, affording bis-NHC complexes with 2-fold symmetry. The X-ray structural characterization of the Rh complex containing thepyracenebis(imidazolylidene) ligand is also reported. The new bis-NHC ligand consists of twolinearly opposed (Janus-type) imidazolylidenes annulated to both sides of a pyracene skeleton.