The cluster structure of crystalline phases according to TGA/DTA and XPS data in isodimorphic substitution series [Cu x Ni(1−x){N(CH2PO3)3}]Na4·nH2O (x = 0 … 1)

Abstract

The cluster structure, thermochemical behavior, and some mechanisms of thermal decomposition of the crystalline products in the isodimorphic substitution series Cu _x Ni_(1−x)NTP (x = 0 … 1) have been studied by simultaneous the thermal gravimetric analysis and differential thermal analysis (TGA/DTA) and X-ray photoelectron spectroscopy (XPS). The complexes NiNTP and Cu_1/8Ni_7/8NTP with a monoclinic crystal structure are the most thermo-stable and characterized by one-step decomposition at 400–440 °C with the formation of metal phosphides and phosphates. The complexes Cu_3/8Ni_5/8NTP–Cu_3/4Ni_1/4NTP with the triclinic crystal lattice and the trigonal-bipyramidal coordination of metal atoms decompose in two steps. Firstly, the formation of a heteroligand complex with imino-bis-methylenephosphonic and methylphosphonic acids takes place at 245 °C. Secondly, the complex decomposes at 270–380 °C. The monometallic complex CuNTP decomposes almost completely at 280–300 °C.