Lanthanide complexes of some high energetic compounds ( I), crystal structures and thermal properties of 3-nitro-1,2,4-triazole-5-one (NTO) complexes

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The title complexes with NTO ligand, [Pr 2(NTO) 4(H 2O) 10]·2NTO·6H 2O, I; [Gd(NTO) 2(H 2O) 6]·NO 3·2H 2O, II; [Ho(NTO) 2(H 2O) 6]·NO 3·2H 2O, III, have been synthesized and their crystal structures analyzed by X-ray diffraction methods. Complex I crystallized in the monoclinic Pc space group; II, triclinic Pī; III, monoclinic P2 1/ n. In complex I, the Pr(III) atoms have two different coordination numbers. Ten coordinated Pr(1) atom forms two five-membered chelate rings by combining two NTO ligands bridged to Pr(2) atom. Eight coordinated Pr(2) atom has two terminal NTO ligands and two NTO ligands bridged to Pr(1) atom. Bridging of NTO ligands between Pr(1) and Pr(2), give a novel infinite one-dimensional coordination polymer. There are two free NTO molecules and six crystalline water molecules in the crystal lattice. In iso-structural complexes II and III, the Gd(III) and Ho(III) atoms have eight coordinated by two carbonyl O atoms of two different NTO rings and six water molecules, respectively. There are one NO 3 ion and two crystalline water molecules in the crystal lattice. The crystal structures are stabilized by three-dimensional network of the intermolecular N H ⋯ O Nitrate and N H ⋯ N NTO hydrogen bonds. Based on the results of TG-DTG thermal analysis, the thermal decomposition reaction of complex I was analyzed to have three distinctive stages such as the dehydration of water, the cleavage of NTO ring and the formation of metal oxide, while complexes II and III were proceeded through four stages including the decomposition of NO 3 ion.