Deprotonation of a PNNP-Iron Complex: Expanding the Concept of Metal-ligand Cooperation to the PNNP-Iron System

Iron(II) dichloride coordinated with a phenanthroline-based meridional PNNP ligand [FeCl2(PNNP)] (1) (PNNP = 2,9-bis((diphenylphosphino)methyl)-1,10-phenanthroline) underwent deprotonation upon treatment with tBuONa to afford the corresponding iron(II) complex 2, which bears a deprotonated PNNP ligand with one dearomatized pyridine ring. Single-crystal X-ray diffraction analysis supported the contribution of the charge delocalization both on the ligand and the iron metal in the structure of 2.