Theoretical Study of Mononuclear Nickel(I), Nickel(0), Copper(I), and Cobalt(I) Dioxygen Complexes: New Insight into Differences and Similarities in Geometry and Bonding Nature

Abnormal N-heterocyclic Carbene Based Ni(II) π-allyl Complex towards Molecular Oxygen Activation

Abnormal N-heterocyclic carbene (aNHC) based Ni(II) π-allyl complexes (3 and 4) were synthesized starting from a Ni(0) precursor. These complexes were characterized by NMR spectroscopy, single-crystal X-ray crystallography (4) and elemental analysis data. The underlying mechanism for the formation of Ni(II) η³ -allyl complexes from a Ni(0) precursor on treatment with a free abnormal N-heterocyclic carbene in absence of any external additive or oxidant was unraveled. Later, complex 3 was exposed to O₂ gas under ambient pressure resulting in molecular oxygen activation to form a μ-hydroxo bridged Ni(II) dimer.

Spin crossover dynamics studies on the thermally activated molecular oxygen binding mechanism on a model copper complex

The theoretical description of the primary dioxygen (O₂) binding and activation step in many copper or iron enzymes, suffers from the instrinsically electronic non-adiabaticity of the spin flip events of the triplet dioxygen molecule (³O₂), mediated by spin–orbit couplings.

Theoretical view on a linear end-on manganese–dioxygen complex bearing a calix[4]arene ligand

The Mn–O–O angle of mononuclear manganese(iii)-superoxo complexes supported by zwitterionic calix[4]arene ligands can be modulated via solvent polarity perturbations and/or ligand size adjustment as indicated by DFT calculations.

Different Interaction Mechanisms of Eu(III) and (243)Am(III) with Carbon Nanotubes Studied by Batch, Spectroscopy Technique and Theoretical Calculation

Herein the sorption of Eu(III) and (243)Am(III) on multiwalled carbon nanotubes (CNTs) are studied, and the results show that Eu(III) and (243)Am(III) could form strong inner-sphere surface complexes on CNT surfaces. However, the sorption of Eu(III) on CNTs is stronger than that of (243)Am(III) on CNTs, suggesting the difference in the interaction mechanisms or properties of Eu(III) and (243)Am(III) with CNTs, which is quite different from the results of Eu(III) and (243)Am(III) interaction on natural clay minerals and oxides. On the basis of the results of density functional theory calculations, the binding energies of Eu(III) on CNTs are much higher than those of (243)Am(III) on CNTs, indicating that Eu(III) could form stronger complexes with the oxygen-containing functional groups of CNTs than (243)Am(III), which is in good agreement with the experimental results of higher sorption capacity of CNTs for Eu(III). The oxygen-containing functional groups contribute significantly to the uptake of Eu(III) and (243)Am(III), and the binding affinity increases in the order of ≡S-OH < ≡S-COOH < ≡S-COO(-). This paper highlights the interaction mechanism of Eu(III) and (243)Am(III) with different oxygen-containing functional groups of CNTs, which plays an important role for the potential application of CNTs in the preconcentration, removal, and separation of trivalent lanthanides and actinides in environmental pollution cleanup.

On the reaction mechanism of the complete intermolecular O2 transfer between mononuclear nickel and manganese complexes with macrocyclic ligands

The recently described intermolecular O2 transfer between the side-on Ni-O2 complex [(12-TMC)Ni-O2](+) and the manganese complex [(14-TMC)Mn](2+), where 12-TMC and 14-TMC are 12- and 14-membered macrocyclic ligands, 12-TMC=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane and 14-TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, is studied by means of DFT methods. B3LYP calculations including long-range corrections and solvent effects are performed to elucidate the mechanism. The potential energy surfaces (PESs) compatible with different electronic states of the reactants have been analyzed. The calculations confirm a two-step reaction, with a first rate-determining bimolecular step and predict the exothermic character of the global process. The relative stability of the products and the reverse barrier are in line with the fact that no reverse reaction is experimentally observed. An intermediate with a μ-η(1):η(1)-O2 coordination and two transition states are identified on the triplet PES, slightly below the corresponding stationary points of the quintet PES, suggesting an intersystem crossing before the first transition state. The calculated activation parameters and the relative energies of the two transition sates and the products are in very good agreement with the experimental data. The calculations suggest that a superoxide anion is transferred during the reaction.

DFT/TDDFT insights into the chemistry, biochemistry and photophysics of copper coordination compounds

Highlighting the recent progress in DFT/TDDFT application to coordination chemistry of copper.