Exploring the Coordination Chemistry of N with Technetium PNP Pincer-Type Complexes

Dinitrogen (N) complexes of technetium (Tc) are rare, and only two examples have been reported. To complement this important class of complexes also for Tc, two different pincer-type complexes of Tc were studied to assess their abilities for coordinating dinitrogen. The reactions of the Tc complex [TcCl(PPh)(NCCH)] with the pincer ligands PNP and PNP respectively gave [Tc(PNP)Cl] and [Tc(PNP)Cl], the first structurally characterized Tc complexes with -coordinated pincer ligands. Reductions with [Co(Cp*)] under N gave the mononuclear bis-dinitrogen complex [Tc(PNP)(N)] and the dinuclear complex [Tc(PNP)(N)Cl](μ-N) with both a bridging and a terminal N ligand. Spectroscopy and crystal structures confirm their identities. The complexes are stable under a dinitrogen atmosphere, and the N ligands are tightly bound. The results for the complexes with the PNP pincer allow a comparison to its rhenium homologue, which has recently been shown to split the N ligand with the formation of a nitrido complex.