Bis(triazenide), tris(triazenide), and lantern-type of triazenide iron complexes: Synthesis and structural characterization

Abstract A commercially available triazine, PhNNN(H)Ph, served as a monoanionic bidentate ligand upon deprotonation using Fe[ N ( SiMe 3 ) 2 ] 2 . By simply using different ethereal solvents, the bis(diethylether) and bis(tetrahydrofurane) complexes of Fe[ PhNNNPh ] 2 , 1 and 2 , can be prepared successfully. The structures of 1 and 2 were confirmed by single crystal X-ray diffraction studies and supported by NMR spectroscopy and elemental analysis. Interestingly, the solid-state structure of 1 exhibits two Et 2 O ligands coordinated to Fe(II) in a trans manner, whereas 2 shows two THF solvents bound to Fe(II) in a cis fashion. The tris(homoleptic) Fe(III) complex 3 was obtained upon oxidation in air, and the one electron reduced counterpart 4 can be synthesized when treating 3 with KC 8 . One of the reduced by-products was crystallized and confirmed as a lantern-type diiron complex [Fe 2 (μ-N,N′-PhNNNPh) 4 ], 5 , by single crystal X-ray diffraction. Remarkably, the Fe Fe bond of 2.1901(4) A in 5 is among the shortest Fe(II)  Fe(II) bond.