Thermal evolution and crystal structure of a polymeric complex: Pb3(3,5-dicarboxylatopyrazole)2(NO3)2·4H2O

Depending on the experimental conditions, different bismuth derivatives of 2,3-dicarboxypyrazine (2,3-H2pzdc) were obtained, corresponding to the compositions Bi(2,3-Hpzdc)3·2H2O (4) and Bi(2,3-Hpzdc)2·OH (5). In line with the analytical results and the infrared spectra, high resolution NMR studies (DMSO-) of anhydrous Bi(2,3Hpzdc)3 (4a) confirmed unequivocally the presence of one free carboxylic acid in the structure. Thermal degradation of 4a in air proceeds in three steps and results in the formation of α-Bi2O3 at moderate temperature (451°C). A bismuth derivative of 3,5-dicarboxypyrazole (3,5-H3Dcp) corresponding to the formula Bi2(3,5-Dcp)2·nH2O (3) was obtained from bismuth nitrate and the dicarboxylic acid in hot water. It decomposes into α-Bi2O3 when heated in air at 385°C. The starting compounds and their thermal degradation products were also examined with X-ray photoelectron spectroscopy.

B. Mernari

Papers

Synthesis and microstructure of bismuth-based mixed metal oxides from organic precursors

A Coprecipitation Process Using Heterocyclic Diacids for the Preparation of Conducting Oxides