title: Main-chain organometallic polymers comprising redox-active iron(II) centers connected by ditopic N-heterocyclic carbenes.
abstract: Main-chain organometallic polymers were synthesized from bimetallic iron(ii) complexes containing a ditopic N-heterocyclic carbene (NHC) ligand [(cp)(CO)LFe(NHC approximately NHC)Fe(cp)(CO)L]X(2) (where NHC approximately NHC 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 AgBF(4)-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.
authors.affiliation: Department of Chemistry, University of Fribourg, Chemin du Musee 9, CH-1700 Fribourg, Switzerland.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Mercs
authors.forename: Antonia
authors.initials: A
authors.lastname: Neels
authors.forename: Helen
authors.initials: H
authors.lastname: Stoeckli-Evans
authors.forename: Martin
authors.initials: M
authors.lastname: Albrecht
mesh_terms: D018360:Crystallography, X-Ray; D005296:Ferrous Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D005296:Ferrous Compounds; D006571:Heterocyclic Compounds; D008024:Ligands; D011108:Polymers; C030011:carbene; D008697:Methane