Dinitrogen fixation with low-valent iron and cobalt complexes bearing phosphinidenides

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The general strategy for this project involves the use of NHC/CAAC-phosphinidenes and NHC/CAAC-phosphinidenidesfor the synthesis of iron and cobalt complexes and the subsequent examination of their abilities to fixate dinitrogen under reductive conditions. By merging the expertise of the applicant in NHC-main group element chemistry with the experience of the host institution in iron- and cobalt-chemistry, the isolation of several novel complexes are envisaged. Especially the N2 activation with di- or- tri-nuclear complexes can be regarded as the main target of this investigation. Despite the recent popularity of NHC-phosphinidenes and NHC-phosphinidenides, only few corresponding iron or cobalt complexes were established. Furthermore, the fact that many dinitrogen-iron and -cobalt complexes rely on phosphane based ligands, the investigation of such phosphinidene or phosphinidenide based complexes regarding the change of activity is certainly of interest. In analogy to the (NHC)P– ligand, related CAAC ligands can also be used, since (CAAC)P– ligands in transition metal complexes are not reported yet. The work program is formulated along the following objectives: -Synthesis and characterization of NHC/CAAC-phosphinidenes as ligands as well as transfer reagents for the NHC/CAAC-phosphinidenide moieties -Synthesis and characterization of low valent iron- and cobalt-complexes bearing NHC/CAAC-phosphinidene and -phosphinidenide ligands -Investigation of these complexes regarding dinitrogen fixation and dinitrogen activation under reductive conditions -Investigation of the potential dinitrogen complexes regarding ammonia and N–C/Si bond formation.