Nickel(II) Complexes Incorporating Pyridyl, Imine and Amino Chelate Ligands: Synthesis, Structure, Isomer Preference, Structural Transformation and Reactivity Towards Nickel(III) Derivatives

Abstract

Facile condensation of 2-acetylpyridine with ethylenediamine in a 1:1 or 2:1 molar ratio yielded two neutral ligands with different denticity: 1-amino-4-(2-pyridyl)-3-azapent-3-ene (tridentate, L 1 ) and 2,7-bis(2-pyridyl)-3,6-diazaocta-2,6-diene (tetradentate, L 3 ), respectively. Replacing the ketone with 2-pyridinecarboxaldehyde gave a similar set of condensates (

Synthesis, characterization and molecular structures of Ni(II) complexes derived from Schiff base pyridylimine ligands

“…The NiL1 (15) Å] is close to those observed in other aqua nickel complexes [17,18,[25][26][27][28][29][30][31], lengths for Ni-N imine and Ni-N pyridyl bonds are in accordance with other structurally similar complexes [15,[17][18][19]32,33].…”

“…In cation [Ni(L1)(H 2 O)Cl] + the N4 imine −Ni1 bond distance [2.0646(16) Å] is shorter than that observed for the N1 imine −Ni1 [2.0891(16) Å] bond, this effect has been attributed to the π acceptor ability of the imine nitrogen backbonding [17]. This backbonding effect is promoted by the presence of the trans N2 pyridine atom (strong σ-donor) that is sharing the same d orbital of the metal as the Ni donor.…”

“…Whilst group 10 transition metal complexes based on pyridylimine ligands have been synthetized being important those of nickel [15,[17][18][19] for their potential as models for the mimicking of active centers of metalloenzymes. Thus, in this report we would like to report our findings on the synthesis, characterization and supramolecular studies in the solid state of a series of Ni(II) complexes derived from pyridylimine ligands.…”

New manganese-based catalyst systems for alkyd paint drying

“…Despite the fact that the ligands L1 and L2 in solution are not present as such, upon the addition of a metal ion due to the chelating effect the "open" tridentate ligands are predominant, as is confirmed by the complexation studies reported earlier [27][28][29]. The ligand L3 is present in solution as such, and it has been reported as a ligand for iron complexes used in oxidation catalysis [30].…”

“…Although coordination complexes of the ligands L1 [27,28] and L2 [29] have been reported, these ligands mostly have been prepared and used in situ and have not been characterized with NMR. Reexamination of the ligand solutions used in our studies with ESI-MS and NMR has shown that a 1:1 mixture of 2-Scheme 3.…”