Synthesis, characterization, and thermal analysis of two polymeric chromium ternary complexes with nitrilotriacetic acid and alanine or glycine

Abstract

Two chromium ternary complexes with nitrilotriacetic acid as a primary ligand and alanine or glycine as secondary ligand were prepared in slightly acidic medium. The structure of these two complexes was characterized using elemental, thermal analysis, FTIR spectra, and the two complexes mass spectra. The spectroscopy data suggest that these two complexes were in polymeric form and have the monomeric unit H[Cr(HNTA)(Hala)(SO 4 )] and H[Cr(HNTA)(Gly)(SO 4 )] in which sulfate group act as a bidentate ligand linked between each monomeric unit for the same complex.

Design of Novel Oligomeric Mixed Ligand Complexes: Preparation, Biological Applications and the First Example of Their Nanosized Scale

“…The molecular masses of all complexes insinuated the presence of the sulfate group (SO 4 2− ) as a ligand (Table 1). A simple test of the BaCl 2 solution was performed on all the complexes as evidence that the sulfate groups act as ligands not as counter ions [48,49].…”

“…Meanwhile, the glutamic acid, which converted to azwitter ion form (H 3 N + CH 2 COO − ), worked as a monodentate ligand and coordinated via its carboxylic oxygen [51]. Thus, the octahedral structure of each monomeric unit is formed via two oxygen and one nitrogen atoms of the HNTA −2 moiety combined with the carboxylic groups of the glutamic acid and the two halves of the sulfate groups, which bind to the metal ions as bridged bidentate ligand, forming the oligomeric materials [49]. The proposed structure of this oligomeric series is illustrated in Figure 1.…”

“…The thermal decomposition of all oligomers displayed similar patterns as their ligand precursors. For instance, it is renowned that H 3 NTA is thermally decomposed in two overlapping steps into glycine and maleic acid [49] while glutamic acid decomposes, producing glycine, CO 2 and C 2 H 4 [62]. The correlations between the different decomposition steps of the coordinated oligomers with the corresponding weight losses is discussed in terms of the proposed formula of their complexed monomers.…”

Effect of Organic Additives on the Structure and Hydrotreating Activity of a CoMoS/Multiwalled Carbon Nanotube Catalyst

“…41 It is known that being in the composition of complexes with transition metals, NTA is thermally decomposed in two successive stages into glycine and maleic acid. 42,43 In our case, the first maximum of weight loss of about 6. In addition, intense weight loss for all CoMo samples at temperatures above 400 °C is observed, which is due to the decomposition of Co and Mo complexes to their corresponding oxides 44 and the destruction of MWCNTs.…”

“…The addition of NTA as a chelating agent in the synthesis of CoMo catalysts can lead to the formation of complexes with Co ([Co­(NTA)­(H 2 O) 2 ] 2– ) and Mo ([MoO 3 (NTA)] 3– ) in the solution . It is known that being in the composition of complexes with transition metals, NTA is thermally decomposed in two successive stages into glycine and maleic acid. , In our case, the first maximum of weight loss of about 6.1 wt % at 240 °C corresponds to the loss of one glycine molecule because of the decomposition of the NTA ligand. The second weight loss at 325 °C is about 3.5 wt % and can be interpreted as the decomposition of the NTA ligand to maleic acid.…”