(E)-2-{[(2-Aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butyl-phenol ( 3: ), a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, ¹H-NMR, 13C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL) charge transfer.

In a recent beam deflecting experiment was found that high and low spin states of pure Fe n and Co n clusters with n ≤ 300 atoms coexist at cryogenic temperatures. In this work we have studied the high spin (HS) and low spin (LS) states of several structural isomers of Co23, Co34, Fe34, and Fe40 using the generalized gradient approximation (GGA) to density functional theory as implemented in the first-principles pseudo-potential code SIESTA. The calculated energy difference between these HS and LS isomers is not consistent with the observed coexistence, which can be due to an insufficient account of many body correlation effects in the GGA description, or to unknown isomer structures of these clusters. We have calculated within the same tools the magnetic isomers of Co12Cu cluster aimed to re-visit a former DFT prediction of an anti-ferromagnetic ground state. We find, however, a ferromagnetic ground state as expected on physical grounds. Our results exemplify the difficulties of the current DFT approaches to describe the magnetic properties of transition metal systems.

Hemos estudiado estados magnéticos de alto y bajo espín en los agregados Co23, Co34, Fe34 y Fe40, por medio de la aproximación de gradientes generalizada a la teoría del funcional de la densidad (DFT). Nuestro propósito era explicar la coexistencia de dichos estados observada recientemente en experimentos tipo Stern-Gerlach sobre haces de agregados de Cobalto y de Hierro a temperatura criogénica. Los cálculos predicen una diferencia en la energía de esos estados magnéticos demasiado grande para que puedan coexistir a la temperatura del experimento. Esto indica que el nivel teórico no es suficiente para dilucidar estos efectos magnéticos finos, o, más probablemente, ninguna de las estructuras optimizadas corresponde a la del estado fundamental. Por otro lado, usando la misma herramienta computacional, predecimos un estado base ferromagnético para Co12Cu, como cabe esperar por intuición física, mientras cálculos DFT previos predicen un estado antiferromagnético.

The oxidation product of the binuclear copper (I) complex Cu2L(ClO4)2 (L = N,N'-bis-(6-methyl-2-pyridil) (2'-pyridyl)methyl m-xylylidene imine) has been isolated and structurally characterised. In the cupric species, [Cu2L(Me-O)2](ClO4 )2, the metal centres are bridged by two methoxide groups, and the oxygenation of the xylyl spacer of the hexadentate ligand is not observed. The copper(I) complex was found to be a catalyst for the oxidation of 3,5-ditertbutylcatechol to 3,5-ditertbutyl-o-benzoquinone by molecular oxygen