The Reactivity of the Imine Bond within Polynuclear Nickel(II) Complexes

Abstract

Three novel Ni complexes with the Schiff base ligand 2-methoxy-6-(E-2-pyridyliminomethyl)-phenol (L1) are described. In comparison with the similar 2-(pyridine-2-ylimino-methyl)phenol (pymp), the mode of coordination of L1 is altered due to the presence of methoxy substituent introducing the sterical hindrance. During the synthesis of the complexes, partial hydrolysis of the ligand was observed. Since such immediate hydrolysis of L1 was not detected during the reactions of Zn(II) and Cu(II) salts with L1, the DFT calculated structures of a series of similar Zn, Cu, Ni, and Co complexes with L1 are compared to account for the phenomenon.

Reactions of cobalt(ii) chloride and cobalt(ii) acetate with hemisalen-type ligands: ligand transformation, oxidation of cobalt and complex formation. Preliminary study on the cytotoxicity of Co(ii) and Co(iii) hemisalen complexes

“…The previous DFT calculations “foresaw” the coordination geometry of Co( ii ) in C3 very well. 39 The detailed comparison between experimental and theoretical structure is included in ESI as Fig. 3S and Table 2S †…”

“…Previous DFT calculations for a series of transition metal complexes with L1 indicated quasi-three-coordination of one of the imine ligands. 39 Now, we are able to present the experimental crystal structure, which conrms that the distortion results from the interaction between Co(II) and one of the pyridyl nitrogens (N4). Experimental Co(II)/N4 distance equals to 2.711(1) Å.…”

“…This resulted in the formation of various heteroligand complexes. 39 Since the results were unexpected to us, we decided to study the behavior of cobalt( ii ) salts towards similar imines. In this work we describe the reactions that undergo between cobalt chloride or cobalt acetate and selected hemi-salen-type imines in various solvents; we indicate important differences in the reaction course that result from a given choice of reagents and solvents.…”

Coordinative Unsaturation in an Antimony(III)-Complex with the 2-Salicylidenaminophenolato Ligand: Synthesis, Crystal Structure, Spectroscopic Analysis, and DFT Studies

“…As a flexible ligand system, Schiff bases can be used. Metal-Schiffbase complexes are quite common, e.g., [18][19][20][21][22][23][24]. These complexes have many different biomedical applications [25,26], as well as the use as catalysts (e.g., [10]), as sensors for copper [27], for use in non-linear optics [28], and for the generation of polynuclear magnetic complexes [29][30][31].…”

Synthesis and Crystal Structure of Dimethyl{N-[(2-oxy-1-naphthyl)methylene]leucinato}silicon

“…The reaction of aromatic ortho-hydroxycarbonyl compounds with amino acids allows access to versatile Schiff base ligands. These act as tridentate O,N,O-ligands in the coordination of a wide range of metal ions; see, for instance, [1][2][3][4][5][6]. The possible applications of these complexes are manifold.…”