Synthesis, structure, and properties of nitrilo-tris(methylenephosphonato)-triaquairon(II) {Fe[µ-NH(CH2PO3H)3](H2O)3}, as an ingredient of anticorrosive protective coatings on the steel surface

A new non-electrolyte complex of iron(II), {Fe[μ-NH(CH₂PO₃H)₃](H₂O)₃}, has been synthesized and investigated. The crystallographic characteristics of the complex are as follows: sp. gr. P2_1/c, Z = 4, a = 9.2619(3) Å, b = 16.0548(3) Å, c = 9.7570(3) Å, and β = 115.685(4)°. The iron atom is octahedrally coordinated by the three phosphonate oxygen atoms and three water molecules in the meridional configuration. The complex has a coordination polymer structure; each Fe atom closes the eight-membered chelating cycle Fe–O–P–C–N–C–P–O, and one of the phosphorus atoms of this cycle is bound with an iron atom of a neighboring structural unit.