Synthesis and Characterization of Novel Iron(II) Complexes with Tetradentate Bis(N-heterocyclic carbene)–Bis(pyridine) (NCCN) Ligands
By Raba, Andreas; Cokoja, Mirza; Ewald, Stefan; Riener, Korbinian; Herdtweck, Eberhardt; Pöthig, Alexander; Herrmann, Wolfgang A. & Kühn, Fritz E.
Published in Organometallics
NULL
2012
Abstract
Three novel iron(II) complexes bearing tetradentate ligands of the type pyridine -bis(N-heterocyclic carbene) -pyridine (NCCN) have been synthesized. The compounds trans-diacetonitrile[bis(o-imidazol-2-ylidenepyridine)alkane]iron(II) hexafluorophosphate (alkane = methane (2a), ethane (2b)) and cis-diacetonitrile[1,3-bis(o-imidazol-2-ylidenepyridine)propane]iron(II) hexafluorophosphate (2c) have been characterized by single-crystal X-ray diffraction (XRD), nuclear magnetic resonance spectroscopy (NMR), and infrared spectroscopy (IR). Cyclic voltammetry (CV) measurements show reversible oxidation of Fe(II) to Fe(III). The rotational barrier of the bridge has been determined via variable-temperature NMR (VT-NMR) studies of 2b. In all complexes, the Fe centers coordinate--in addition to the NCCN ligands--two acetonitrile ligands in the solid state as well as in solution. The alkylene bridge connecting the two NHCs has an influence on the coordination mode of the NCCN ligands. Whereas the methylene- and ethylene-bridged NHC moieties lead to a nearly planar geometry of the NCCN ligand and two trans-positioned acetonitrile ligands, the propylene-bridged complex 2c exhibits a sawhorse-type coordination mode, with two cis-oriented acetonitrile ligands. The reactivity of the synthesized complexes toward substitution of the solvent ligands was investigated, showing that acetonitrile is readily substituted by benzonitrile. Upon addition of carbon monoxide, one acetonitrile ligand is replaced by CO to yield complexes 3a -c, as shown by NMR and IR spectroscopy, as well as by XRD in the case of compound 3c.
Microsoft is Ending Support for Windows 7
Microsoft will discontinue support for Windows 7 on January 14, 2020 which means Gamry will also be discontinuing support for Windows 7. If you are upgrading to Windows 10, like many companies and institutions, you need to be running Version 7 of our s oftware . Please note that only USB and Ethernet-based instruments can run in Version 7. Eligible users can download the latest version of our software through our online Client Portal .
If you haven't already registered your instrument, you can do so through the Client Portal .
Please email Technical Support if you have any questions regarding this transition. Please be sure to include your instrument model and serial number when contacting us.