Thermal stability and thermal decomposition mechanism of nitrilotris(methylene phosphonate) complexes of copper and zinc with varied coordination

Abstract

Thermogravimetry, XPA, and ESCA were used to study the thermal stability and decomposition mechanism of [Cu(H2O)3μ-N(CH2PO3)3H4], [Zn(H2O)3μ-N(CH2PO3)3H4], Na8[CuN(CH2PO3)3]2·19H2O, and Na4[ZnN(CH2PO3)3]·13H2O in the atmosphere of air and argon. It was shown that the decomposition point, decomposition mechanism, and composition of the products being formed depend on the composition and structure of coordination compounds, and for Na8[CuN(CH2PO3)3]2·19H2O m Na4[ZnN(CH2PO3)3]·13H2O, also on the composition of the atmosphere. The stability of the complexes is affected by the configuration of the coordination polyhedron and by the electron density distribution in the coordination environment of a metal. The complex Na4[ZnN(CH2PO3)3] has the highest thermal stability in both air and argon (onset of decomposition at about 400°C).