Structures of a Tetradentate Ferrocenyl Ligand and Its Oxorhenium(V) Complex in Solution and in the Solid State

The novel ferrocenyl ligand rac-1,6-diferrocenyl-N,N‘-bis(2-hydroxypropyl)-2,5-diazahexane (1, H2L) was
synthesized from ferrocenylcarboxaldehyde and ethylenediamine followed by the reduction of the Schiff base
with LiAlH4 and subsequent N-alkylation with 1,2-propyleneoxide. The dianion of H2L reacted with [ReO(PPh3)2Cl3], and the product was treated with NH4PF6 to afford the complex [ReO(L-N2O2)PPh3]PF6 (2). Both the ferrocenyl
ligand and the complex were characterized in solution by NMR spectroscopy and in the solid state by single-crystal X-ray diffraction studies. NMR investigations reveal two solvent-dependent isomers for the ferrocenyl
ligand in solution of which the major form is the more ordered one. The cation of 2 displays a nonsymmetrically
coordinated N2O2 ligand.