Synthesis and Structure of Homoleptic Iron Complex Bearing Pincer-Type 1,2,3-Triazol-5-ylidene

Haruka Iwasaki,Yuji Koga

doi:10.4172/2161-0401.1000161

Abstract

Novel iron(II) complex bearing pyridine-bridged bis(1,2,3-triazol-5-ylidene) ligand was synthesized. During many attempts to obtain the compounds, we found generation of dicationic homoleptic iron(II) complex with two tridentate ligands. Analogous monocationic complex with only one tridentate ligand, which is an unstable intermediary complex during formation of the dicationic complex was detected. Structural identification of the homoleptic dicationic product revealed that octahedral geometry stabilized the iron complex and also π-stacking interaction exists between these two tridentate ligands.

Highlights

Mesoionic carbene (MIC) as a ligand component in metal complexes is recently focused as an alternative version of N-heterocyclic carbene (NHC), which is widely developed and utilized for functional materials such as catalysis and photochemical devices in these decades [1,2]
Among MIC molecules, 1,2,3-triazol-5ylidene, which is reported by Albrecht et al [4] and isolated by Bertrand et al [5] has a synthetic advantage toward classical NHC
The crystal structure of 4b as shown in Figure 4, showed that two molecules of the tridentate ligand coordinate to cationic iron to form octahedral geometry accompanied with counter anion, (FeCl3)2(μ-O)2, which could be generated by oxidation of FeCl3- under air

Summary

Introduction

Mesoionic carbene (MIC) as a ligand component in metal complexes is recently focused as an alternative version of N-heterocyclic carbene (NHC), which is widely developed and utilized for functional materials such as catalysis and photochemical devices in these decades [1,2]. Many examples of MICs as ligands for transition metal complexes containing Pd, Ru, Rh, Ir, Ag, Au and Cu have been reported in the recent years [1,2,3,9,10,11,12,13]. These metal complexes are applied to catalysis for organic transformations and photoelectronic devices. The compounds 2a and 2b are reduced to form 3a and 3b, respectively, in good yields (Scheme 2) [23] They are rare examples of the isolated MIC. Even if stoichiometric amount of the carbene ligand was added to iron halides, two molecules of the carbene coordinated to form dicationic homoleptic iron complex 4 with stepwise liberation of two halide anions from iron halides

Methods

Results

Conclusion