Electronic structure and stability of transition metal acetylacetonates TM (AcAc)n (TM = Cr, Fe, Co, Ni, Cu; n=1, 2, 3)

Transition metal acetylacetonates have a wide range of technological applications, such as modifiers in polymers and polymerization catalysts. Since the electronic structure defines the physical-chemistry properties of these materials and ultimately their selectivity in technological applications, its characterization is of paramount importance. In this work, the general trends on the electronic structure of the transition metal acetylacetonate TM(AcAc) were estimated from qualitative and quantitative approaches. The qualitative picture, based on the ligand field theory, allowed to establish a relation between the d-orbital electron occupancy and the stability of the system, in which the Cu(AcAc)(2) presents a limitrophe case, indicating moderate stability and reactivity. On the quantitative approach, the low-lying electronic states of TM(AcAc) were characterized by highly correlated methods. The thermodynamic and kinetic stabilities of TM(AcAc)(n) were ranked by using a stability index based on parameters of the wavefunction, namely, the excitation energy, the free energy of atomization, and the HOMO energy, showing a good agreement with the qualitative results. Besides the spectroscopic data provided for TM (AcAc)(n), the combined qualitative and quantitative results can guide the choice of a specific TM(AcAc)(n) in applications that require higher or lower stabilities.

Automated summary

This study estimated the electronic structure trends of transition metal acetylacetonates through qualitative and quantitative methods. The qualitative description based on ligand field theory established a relationship between electron occupancy and system stability, while the quantitative method characterized low-lying electronic states. The stability of TM(AcAc)(n) was ranked using a stability index based on wavefunction parameters, showing good agreement with the qualitative results and guiding the selection of TM(AcAc)(n) for applications with varying stability requirements.