Synthesis, structural and spectral studies of 5-methyl 2-furaldehyde thiosemicarbazone and its Co, Ni, Cu and Cd complexes

Abstract

The reaction of cobalt, nickel, copper and cadmium chlorides and bromides with 5-methylfurfural thiosemicarbazone (M5FTSC) leads to the formation of two series of new complexes: [M(M5FTSC) 2 X 2 ], [M(M5FTSC)X 2 ]. They have been characterized by spectroscopic studies (infrared, 1 H NMR, and electronic spectra). The crystal structures of the free ligand M5FTSC and of the compound [CuCl 2 (M5FTSC)] have been determined by X-ray diffraction methods. For the Co(II), Ni(II) and Cu(II) complexes, the central atom is coordinated through the sulphur atom and the azomethine nitrogen atom whilst for the Cd(II) complexes, the coordination atoms are the sulphur and furanic oxygen atoms instead of the azomethine nitrogen.

New Copper(II) and Nickel(II) Complexes of 4‐Morpholinoaceto‐ phenone Thiosemicarbazone: Structural, Electrochemical and Antimicrobial Studies

“…This is a consequence of the coordination of the sulphur from the C＝S(NH 2 ) group as reported earlier. 7,28 This coordination is confirmed by the presence of a new band at 380-395 cm -1 that can be assigned to (M-S) for all complexes. 28,29 In the ligand spectrum, the strong band observed at 1600 cm -1 can be assigned to (C-N) frequencies.…”

Tiossemicarbazonas: métodos de obtenção, aplicações sintéticas e importância biológica

“…O caráter parcialmente duplo da ligação C-N pode também ser facilmente evidenciado pela técnica de espectrometria de ressonân-cia magnética nuclear de hidrogênio (RMN 1 H), uma vez que os hidrogênios em NH 2 aparecem como dois sinais não equivalentes. Isto acontece devido à rotação restrita da ligação C-NH 2 por conta da dupla ligação parcial que, desta forma, torna os hidrogênios diastereotópicos 24,25 . A temperaturas elevadas (~ 323 K) estes sinais coalescem como mostra o trabalho de Ferrari e colaboradores 26 .…”

“…Vale ressaltar que o baixo valor da banda de estiramento de C=S é devido ao seu acentuado caráter de ligação simples, e que esta pode variar de acordo com o ambiente quími-co [29][30][31][32] . Obviamente, complexos metálicos de tiossemicarbazonas mudam consideravelmente a posição destas bandas, principalmente aquelas que estão envolvidas na ligação coordenada 25,33 . Bharti e colaboradores 27 obtiveram complexos de paládio e observaram deslocamentos negativos (14-39 cm -1 ) para a banda de C=N, que aparece normalmente entre 1556-1630 cm -1 , indicando o envolvimento da função azometina na ligação coordenada, assim como para a tiocarbonila (C=S), onde as bandas foram deslocadas para freqüên-cias menores (13-35 cm -1 ).…”

Physicochemical studies and biological activity of mixed ligand complexes involving bivalent transition metals with a novel Schiff base and glycine as a representative amino acid

“…Schiff base metal complexes attract considerable interest and occupy an important role in the development of the chemistry of chelate systems [12,13] due to the fact that especially these with N2O2 tetradentate ligands, such systems closely resemble metallo-proteins. Survey of the literature reveals an excellent work devoted to synthesis and characterization of many metal complexes of Schiff base [14][15][16][17]. Additionally, it has been reported that Schiff bases and their first-row transition metal complexes can exhibit fungicidal, bactericidal, antiviral and antitumor activities in addition to their important roles in catalysis and organic synthesis [18][19][20].…”