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Dalton Transactions

The international journal for inorganic, organometallic and bioinorganic chemistry



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Dalton Trans., 2009, 7168 - 7178, DOI: 10.1039/b907018d

Main-chain organometallic polymers comprising redox-active iron(II) centers connected by ditopic N-heterocyclic carbenes

Laszlo Mercs, Antonia Neels, Helen Stoeckli-Evans and Martin Albrecht

Main-chain organometallic polymers were synthesized from bimetallic iron(II) complexes containing a ditopic N-heterocyclic carbene (NHC) ligand [(cp)(CO)LFe(NHCNHC)Fe(cp)(CO)L]X2 (where NHCNHC represents a bridging dicarbene ligand, L = I- or CO). Addition of a diimine ligand such as pyrazine or 4,4-bipyridine, interconnected these bimetallic complexes and gave the corresponding co-polymers containing iron centers that are alternately linked by a dicarbene and a diimine ligand. Diimine coordination depended on the wingtip groups at the carbene ligands and was accomplished either by photolytic activation of a carbonyl ligand from the cationic [Fe(cp)(NHC)(CO)2]+ precursor (alkyl wingtips) or by AgBF4-mediated halide abstraction from the neutral complex [FeI(cp)(NHC)(CO)] (mesityl wingtips). Remarkably, the polymeric materials were substantially more stable than the related bimetallic model complexes. Electrochemical analyses indicated metal–metal interactions in the pyrazine-containing polymers, whereas in 4,4-bipyridine-linked systems the metal centers were electronically decoupled.

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