Magnetic behaviour of bimetallic layered phases M'0.2Mn0.8PS3·0.25 H2O (M' = ZnII, CuII, NiII, CoII)

In this work the magnetic properties of bimetallic phases M'_0.2Mn_0.8PS₃·0.25H₂O (M' = Co^II, Ni^II, Cu^II or Zn^II) have been explored and compared with those of the pristine phase MnPS₃. Magnetic susceptibility, high field magnetization and electron paramagnetic resonance (EPR) studies reveal that the transition temperature between the antiferromagnetic and paramagnetic order for the pristine phase is shifted to lower values in the bimetallic phases. From magnetization measurements the critical field of the spin-flop transition is found to be dependent on the nature of the added secondary transition metal ion. EPR spectra of all compounds in the temperature range of 8-300 K present a single resonance line shape. Temperature dependence of the EPR parameters, like line width, g values and double integrated area (I_DIN), are obtained from the spectra and present a scenario compatible with the magnetization results. The temperature dependence of the first derivative of the product (I_DINT) shows two maxima for all samples, with exception of the Co^II phase, indicating two critical temperatures, while these critical temperatures could not be clearly determined by dc susceptibility.

Models to predict the magnetic properties of single- and multiple-bridged phosphate CuII systems: a theoretical DFT insight

Models for the 1,1 and 1,3-bridging modes of phosphate for copper(ii) compounds were developed. Using unrestricted corresponding orbitals (UCO), a graphical identification of the predominant exchange pathway was described.

Magnetic properties of composites based on the intercalation of ZnII and CuII bimetallic macrocyclic complexes in the MnPS3 phase

EPR and magnetic susceptibility data of composites based on MnPS₃ show the influence of the intercalated species on their magnetic properties.

Nickel nanocomposites: magnetic and catalytic properties

Nickel nanocomposites are obtained under solvothermal conditions by reduction of Ni^II on matrices of polyethylene (Pe) and chitosan (Ch). The composites are weak magnets and are active as catalysts for the hydrogen transfer reaction for acetophenone.

Through-Space and Through-Bond Mixed Charge Transfer Mechanisms on the Hydrazine Oxidation by Cobalt(II) Phthalocyanine in the Gas Phase

Two quantum chemistry theoretical models in the gas phase at the density functional theory B3LYP/LACVP(d) level of calculation are proposed to rationalize the hydrazine oxidation by cobalt(II) phthalocyanine (Co(II)Pc). This oxidation reaction involves the net transfer of four electrons. These theoretical models that are described in terms of energy profiles include a through-space mechanism for the transfer of the first electron of the hydrazine and a through-bond mechanism proposed for the transfer of the three electrons remaining. The main difference between both models arises from a one-electron and one-proton alternate transfer for model 1 and a two-electron and two-proton alternate transfer for model 2. The main problem for experimental studies is to determine if the first transfer corresponds to an electron or a chemical transfer. Under this point of view, we proposed two models which deal with this problem. We conclude that model 1 is more reasonable than model 2 because the whole oxidation process is always exergonic.