Complexation of 16-Membered P4N2 Macrocycles with Fe(II) Ion As Tool for Stabilization of Their RPSPSPRP Stereoisomers

The novel mononuclear Fe(II) complexes of 16-membered P4N2 ligands were synthesized, where octahedral Fe (II) ion is coordinated by four phosphorus atoms of the ligand in equatorial positions and nitrogen atoms of two acetonitrile co-ligands in apical positions. The tetraphosphine ligands demonstrate the RPSPSPRP-configuration regardless of the configuration of the starting stereoisomer of the macrocycles, so that the complexation with iron (II) salts drives up the fixation of this configuration of 1,9-di(R)-1,9-diaza-3,7,11,15-tetraphenyl-3,7,11,15-tetra-phosphacyclohexadecanes, which in turn is favorable for the binding of octahedral metal cations.